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Occurring March 17, it was the biggest explosion in the 8-year history of NASA’s Lunar Impact Monitoring program that shoots continual video of the moon through 14-inch telescopes on Earth. NASA announced the event on May 17 after an analyst noticed the strike on a digital video. Scientists estimate the meteor weighed 88 pounds, was about 16 inches wide, and hit the moon at 56,000 miles per hour.
Steve Roy, Marshall Space Flight Center
An artist’s rendering of a small but powerful meteor strike on the moon.
In this Q&A Smithsonian Geophysicist Bruce Campbell, of the Air and Space Museum’s Center for Earth and Planetary Studies, answers a few questions about the explosion and the geologic processes that shape the moon’s surface. For years Campbell has been using radio telescopes to see through the moon’s thick layer of dust and debris and create a detailed radar map of the moon’s ancient bedrock topography.Q: Can the crater caused by this impact be seen from Earth?
Campbell: There is erosion on the moon which is coming from the exact process that caused this new crater. Think about it, that new 20-meter crater obliterated all the little craters that were in that spot before it. And it threw out dust that covered up and smoothed out other areas.
But even when fresh bedrock from beneath the dust is exposed by very large meteorite strikes, these new rocks are eventually broken down by the little bits of space dust zipping in and striking the moon day in and day out. In general, these tiny particles are traveling extremely fast. Most hit the ground at 2 kilometers per second or more. Even a particle of dust that’s moving at several kilometers per second will break a pretty good chunk off a rock on the ground.
Undetectable from Earth, these little particles are the dominant erosive effect on the moon…on a cosmic time scale these particles are just raining in. This crater is just part of that endless process of the soil gradually building up and rocks on the surface being broken down and craters being smoothed out. If you look at the pictures, the moon’s features are very rounded with gentle slopes; there are almost no sharp-edged hills on the moon.
Alison Mitchell | Newswise
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
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They think scientists will be able to use violations of this principle to map unseen clumps of dark matter in the universe.
Light rays naturally reflect off a curve like the inside surface of a coffee cup in a curving, ivy leaf pattern that comes to a point in the center and is brightest along its edge.
Mathematicians and physicists call that shape a "cusp curve," and they call the bright edge a "caustic," based on an alternative dictionary definition meaning "burning bright," explains Arlie Petters, a Duke professor of mathematics, physics and business administration. "It happens because a lot of light rays can pile up along curves."
Drawn by the mathematically-inclined artist Leonardo da Vinci in the early 16th century, caustics can be seen elsewhere in everyday life, including sunlight reflecting across a swimming pool's surface and choppy wave-light patterns reflecting off a boat hull.
Caustics also show up in gravitational lensing, a phenomenon caused by galaxies so massive that their gravity bends and distorts light from more distant galaxies. "It turns out that their gravity is so powerful that some light rays are also going to pile up along curves," said Petters, a gravitational lensing expert.
"Mother Nature has to be creating these things," Petters said. "It's amazing how what we can see in a coffee cup extends into a mathematical theorem with effects in the cosmos."
From the vantage point of Earth, the entire cosmos looks like a vast interplay of gravity and light that can extend far back into spacetime. "As with any illumination pattern, some areas will be brighter than others," Petters said. "And the brightest parts will be along these caustic curves."
Interpreting data from telescope surveys correctly requires understanding the distortions inherent in lensing, which sometimes warps a more distant point of light into multiple and magnified copies of themselves.
Petters and other researchers have previously found that, if such a light source seems to be juxtaposed within the confines of a caustic arch, two duplicate images will appear to be positioned abnormally close to each other and also seem equally bright. And because these clones are of seemingly equal brightness, subtracting one luminosity from the other results in a difference of zero.
In an article appearing in the March 23 Journal of Mathematical Physics, Petters and graduate student Amir Aazami extended the mathematics of such relatively simple examples to include what Petters called "higher order caustics." In such situations the interplay of light and gravity may extend further into spacetime and undergo various forms of "caustic metamorphosis" in the process.
Aazami was informally testing out a special case of their evolving caustics theorem called an "ellyptic umbilic" by using a technical computing software program called Mathematica when he noticed a pattern.
"It kept getting zero over and over again," Aazami said, no matter what scenario he tried the software on. "So I thought, 'it's making a mistake.' And I went back and looked again, and I kept getting zero. And I said, 'this is beginning to make sense!' That was the 'Ah Ha!' moment."
Petters realized his graduate student had found a universal mathematical principle so pervasive that it can impose balance on the most complicated gravitational lensing illusions. For instance, if lensing produces four light source copies of uneven brightnesses, the relative dimness of some is precisely balanced by the relative luminosity of others so they cancel each other out.
"It's miraculous that they cancel out," Petters said. "This relates to very sophisticated mathematics that you would never think could have anything to do with nature."
The Duke researchers said that for the simplest caustics, the theorem has already been corroborated by a few actual gravitational lensing observations. And they expect the higher order caustics to be observed once the Large Synoptic Survey Telescope (LSST), now being assembled in Chile, begins what Petters called "the most massive survey of the sky known" in a few years.
"We feel very confident that these universal invariants will show themselves in the data to come from the LSST," he said.
Another scenario he predicts are exceptions to the rule: "For one of the higher order caustics, if there are two pairs of lensed images that are close to each other but not equally bright, then the theorem is violated," he said.
"The reason would be some substructure in the galaxy," he said, likely dark matter near one of the images that causes it to be demagnified.
Dark matter is a mysterious substance that astronomers cannot directly observe but can "sense" by its gravitational tug on light. By using the LSST in conjunction with their theorem, astronomers "would be able to identify dark matter substructures in complex galactic systems," Petters predicted
The research was supported by the National Science Foundation.
Monte Basgall | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
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Scientists are excited about solving some of the mysteries surrounding our smallest and hottest planet. The findings are expected to broaden our understanding of rocky planets, more and more of which are being discovered in other solar systems.
At 8:45 p.m. EDT on March 17, the MESSENGER spacecraft will execute a 15-minute maneuver that will place it into orbit around Mercury, making it the first craft ever to do so, and initiating a one-year science campaign to understand the innermost planet.
Mercury is an extreme among the rocky planets in our solar system: It is the smallest, the densest (after correcting for self-compression) and the one with the oldest surface and largest daily variations in surface temperature and the least explored.
Understanding this "end member" among the terrestrial planets is crucial to developing a better understanding of how the planets in our solar system formed and evolved. MESSENGER stands for MErcury Surface, Space ENvironment, GEochemistry and Ranging.
Along with their collaborators on the MESSENGER mission team, several University of Arizona researchers and technical experts are anxiously awaiting the orbit insertion maneuver, which marks the end of the space probe's six-and-a-half year journey to the innermost planet of our solar system.
One of them is Ann Sprague, a research scientist at the UA's Lunar and Planetary Laboratory. Sprague is looking forward to gathering data with the Mercury Atmosphere and Surface Composition Spectrometer, or MASCS, an instrument aboard the MESSENGER spacecraft capable of analyzing light reflected off the planet's surface and scattered by atoms and ions – atoms with an electric charge – above the surface. Both types of light give scientists clues about the composition of the surface.
"By identifying spectral bands and modeling the results we hope to identify the mineral content of the surface materials and eventually figure out what kind of rocks are covering the surface and have come up from below the surface during volcanic events," Sprague said.
When MESSENGER streaked into the early morning sky over Cape Canaveral on Aug. 3, 2004, very little was known about Mercury. No spacecraft had approached the planet since the Mariner 10 space probe performed three fly-by maneuvers over the course of 1974 and 1975, imaging the planet's surface. However, Mariner 10 sent back photos of only one side of the planet, leaving the other shrouded in mystery.
One of the mysteries scientists are hoping to solve with the MESSENGER mission surrounds Mercury's magnetic field. At a diameter only slightly larger than that of the moon (about 4,800 kilometers or 2,983 miles), Mercury should have solidified to the core. However, the presence of a magnetic field suggests the planet's innards are partially molten.
For many decades, scientists such as Sprague and her fellow MESSENGER science team members Robert Strom and William Boynton at the UA's Lunar and Planetary Laboratory were confined to studying Mercury by sifting through Mariner 10 data, making ground-based observations using visible and mid-infrared spectroscopy and by studying data obtained from Mars and meteorites.
"I am most excited to see what MESSENGER will discover about Mercury's exosphere," Sprague said, "because it will tell us a lot about the surface of the planet – what the volatiles, or gases, are in the cold locations and what elements are present in the minerals on the surface."
Lacking an atmosphere, Mercury is surrounded by an exosphere: an invisible, thin region containing atoms and ions. It is generated by the solar wind's charged particles showering down onto the surface. During the process, various chemical elements are kicked up from Mercury's soil. The heavier ones, like sodium and potassium, remain fairly close to the surface until solar photons push them into space, emanating from the planet as a plume almost like that of a comet, except invisible to the naked eye.
"Lighter atoms like hydrogen quickly escape into space and soon are swimming in a sea of hydrogen that permeates our solar system," Sprague explained. "So it's a fine balance between what is heavy enough to be retained around the planet and what is so light that it escapes."
She added: "One quite exciting possibility would be the presence of elemental mercury in the exosphere or on the surface. "We are waiting anxiously to see if we are going to find the spectrographic signal of mercury in Mercury's exosphere."During its journey toward Mercury, MESSENGER passed the planet several times, filling in the imaging gaps left by Mariner 10.
"This is a bit unfortunate because at the North Pole, the spacecraft will be going very low and the view will be distorted," Sprague said. "Over the southern pole, the craft will be several thousand kilometers away, causing the image resolution to be poor and distorted as well."
The polar regions are of great importance, she said, because ground-based radar observations indicate there may be frozen water beneath thin layers of dust in regions where the sunlight never reaches, such as permanently shadowed crater bottoms.
"Alternatively, there may be other exotic volatiles or metals in those dark craters – like mercury, sulfur, sodium chloride or some other substance not thought of or expected. It is exciting and all eyes will be focused on the data that comes back from those polar scans."
Robert Strom, professor emeritus in the UA's Lunar and Planetary Laboratory, said: "Once in orbit, MESSENGER will image the surface at 250 meters per pixel. At its closest approach, it will even get to a resolution of six meters per pixel. Of course, you can't image a whole planet at this fine resolution. This will be reserved for targets of opportunity – features that MESSENGER images during its surveys and that catch our attention."
Strom pointed out that the MESSENGER mission is unusual because its main payload is not the instruments, but the fuel needed to slow the spacecraft down.
"Because the journey from Earth to Mercury goes toward the sun, we need a lot of energy to counteract the sun's gravitational pull," he explained.
To save fuel, the engineers devised a carefully choreographed dance that MESSENGER performs around selected planets: the Earth, the moon and Mercury.
"By having the probe dance around planets, it can take advantage of their gravitational fields to slow its speed," Strom added. "Even once in orbit around Mercury, the spacecraft will need to burn fuel every few hours or so to prevent the sun's gravitational field from pulling it out of orbit."
Another great challenge MESSENGER has to cope with is the intense heat due to Mercury's proximity to the sun. At the equator, surface temperatures become hot enough to melt lead. The heat reflected from the planet's surface is so intense that the spacecraft's instruments need to be shielded against the glare.
"The spacecraft is going to go very fast, traveling around the planet every 12 hours," Sprague explained. "The orbit is highly elliptical to allow the spacecraft to cool down. We couldn't do this with a circular orbit, like around Mars. Everything would just overheat. MESSENGER must swoop in, keeping its sunshade pointed toward the sun, and then it has to swing out far into space so it can cool down."Strom added: "The strategy is to have MESSENGER gather data during its close approach and then read the data out and send them back to Earth while the probe is at a safe distance from the scorching planet."
Scheduled to remain in orbit for a year, MESSENGER will fly around Mercury 730 times. The mission may be extended for another year.The in-flight preparations for the orbit insertion maneuver began on Feb. 8, when several heaters on the spacecraft were configured to condition the bi-propellant used during the maneuver.
"Here at the UA, specialists including Karl Harshman, Dave Hamara, Mike Fitzgibbons, and Jerry Droege have important jobs to keep the data flowing, constantly checking for errors in electronic codes and correctly parsing the data for the scientists," Sprague said.
She pointed out that the mission's significance reaches beyond Mercury.
"Now that so many new planets are being discovered around stars in other solar systems, we need to know the effects of space weathering on rocky surfaces so we can accurately interpret telescopic and other remote sensing data we obtain from other rocky or dusty worlds."
The MESSENGER mission is led by NASA, the Applied Physics Laboratory at Johns Hopkins University and the Carnegie Institution. This article was compiled in part with content from the MESSENGER Mission website (http://messenger.jhuapl.edu).
MEDIA CONTACTS:P. Campbell
D. Stolte | University of Arizona
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 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine | <urn:uuid:4a900127-9fcf-4821-9b42-ff86fb2edafb> | 3.78125 | 2,464 | Content Listing | Science & Tech. | 40.795312 | 95,557,688 |
We used camera traps to survey Geoffroy's cats, Oncifelis geoffroyi, at six dry forest sites in Bolivia. Cumulative activity patterns across all sites are principally nocturnal though the species is active by day in both summer and winter. At two sites the number of captures and recaptures was sufficient to estimate abundance using the software Capture, and in turn a population density of 9-40 per 100 km2 for the two sites. Geoffroy's cats are present in all dry forest types surveyed: Chaco savannas, Chaco dry forest, Chaco transitional forest, Chaco-Chiquitano transitional forest, Chaco-Cerrado transitional forest and Chiquitano dry forest. They are most abundant at the driest site, the only one with grassland formations and where ocelots are absent. Camera trapping records tend to be more numerous in the dry season, suggesting seasonal changes in behavior and habitat use.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:badc341e-6b2d-4216-a733-f482ed4ec8b2> | 3.296875 | 215 | Academic Writing | Science & Tech. | 23.507311 | 95,557,689 |
Stable isotopes are a tool that can be used in a wide range of areas in natural sciences and medicine as, with their help, it is possible to establish the origin of substances, and dynamic processes can be made visible.
For example, it is possible to establish where a red wine really comes from, the cause of water damage, how the concentration of carbon dioxide at the South Pole evolved, whether microorganisms break down pollutants in soil and water or the effects a medication has on the body. Just like with criminal investigators, stable isotopes help environmental researchers to follow traces and solve mysteries.
The research on stable, i.e. non-radioactive, isotopes has been carried out in the Leipzig Science Park for more than half a century and brings together scientists from a range of disciplines.
Leipzig has a long tradition of research in this area. In the 1960s a special institute for stable isotopes was built on the former research site of the GDR's Academy of Sciences at Permoserstraße. The 40-metre tower, which can still be seen from far away today, was used for many years to enrich a range of stable isotopes, with 15N the most important. The UFZ today uses research with stable isotopes in a number of fields.Stable isotopes a kind of "Swiss Army Knife"
http://www.ufz.de/index.php?de=17988Teamwork against Benzene (press release, 26 July 2012):
http://www.ufz.de/index.php?en=22138Drinking water in Gaza Strip contaminated with high levels of nitrate (press release, 14 August 2008):
http://www.ufz.de/index.php?en=17112Erfolgreicher Wissenstransfer (Successful transfer of knowledge) (press release 9 November 2005):
http://www.ufz.de/index.php?de=6345Signs of magmatic activity in Central Europe observed for the first time (press release, 22 September 2005):
http://www.ufz.de/index.php?en=6141At the Helmholtz Centre for Environmental Research (UFZ) scientists are researching the causes and consequences of far-reaching changes to the environment. They are concerned with water resources, biological diversity, the consequences of climate change and adaptability, environmental and biotechnologies, bioenergy, the behaviour of chemicals in the environment, their effect on health, modelling and social science issues. Their guiding theme: Our research contributes to the sustainable use of natural resources and helps to secure this basis for life over the long term under the effects of global change. The UFZ employs 1,000 people in Leipzig, Halle and Magdeburg. It is financed by the federal government and the federal states of Saxony and Saxony-Anhalt.
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
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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We’re less than a month away from the launch of Parker Solar Probe! NASA’s Launch Services Program is hard at work getting the spacecraft ready for launch aboard a United Launch Alliance Delta IV Heavy. Follow along with our countdown to T-zero! nasa.gov/solarprobe
A Northrop Grumman Pegasus XL rocket, carried underneath a modified L-1011 airplane, departed Vandenberg Air Force Base in California on June 6 on the way to Kwajalein Atoll in the Pacific Ocean. The rocket and carrier jet returned to Vandenberg on June 8 after engineers encountered a technical problem with the launch vehicle during the ferry flight. Credit: NASA/Randy Beaudoin
NASA and Northrop Grumman are expected to base the launch of an air-dropped Pegasus rocket with a NASA science satellite from Cape Canaveral later this year, after originally trying to get the mission into space from a remote island in the middle of the Pacific Ocean.
The space agency has not announced the move, but three officials involved in the mission said the launch of NASA’s Ionospheric Connection Explorer — ICON — a small satellite instrumented to study the link between weather on Earth and conditions at the edge of space, is expected to shift from Kwajalein Atoll in the Pacific Ocean to Cape Canaveral.
The air-launched rocket was supposed to send the ICON satellite into orbit June 14. The Pegasus XL rocket was to take off from a U.S. military airfield on Kwajalein Atoll, located in the Marshall Islands in the Pacific Ocean around 2,400 miles (3,900 kilometers) southwest of Honolulu, under an L-1011 carrier jet, then drop from the belly of the aircraft and fire into orbit.
Read the complete Story
A mission 60 years in the making, Parker #SolarProbe will make a historic journey to the Sun’s corona. Discover how a recently-installed heat shield will keep our spacecraft and its instruments at a relatively comfortable temperature of approximately 85 degrees Fahrenheit
The first launch opportunity is just under four weeks away and final preparations are under way. The Thermal Protective Shield, TPS, has been installed to protect the spacecraft from the intense heat of the sun.
Read the whole story
In a background magnetic field, represented by the cyan arrows, two electrons are propagating to the right, executing identical gyromotion. A circularly polarized electromagnetic wave approaches the upper electron from the left.
Encircling Earth are two enormous rings — called the Van Allen radiation belts — of highly energized ions and electrons. Various processes can accelerate these particles to relativistic speeds, which endanger spacecraft unlucky enough to enter these giant bands of damaging radiation. Scientists had previously identified certain factors that might cause particles in the belts to become highly energized, but they had not known which cause dominates.
Now, with new research from NASA’s Van Allen Probes and Time History of Events and Macroscale Interactions during Substorms — THEMIS — missions, published in Geophysical Research Letters, the verdict is in. The main culprit is a process known as local acceleration, caused by electromagnetic waves called chorus waves. Named after their characteristic rising tones, reminiscent of chirping birds, chorus waves speed up the particles pushing them along like a steady hand repeatedly pushing a swing. This process wasn’t a widely accepted theory before the Van Allen Probes mission.
Establishing the main cause of the radiation belt enhancements provides key information for models that forecast space weather — and thus protect our technology in space.
Read the complete article
As we develop more and more powerful tools to peer beyond our solar system, we learn more about the seemingly endless sea of faraway stars and their curious casts of orbiting planets. But there’s only one star we can travel to directly and observe up close — and that’s our own: the Sun.
Two upcoming missions will soon take us closer to the Sun than we’ve ever been before, providing our best chance yet at uncovering the complexities of solar activity in our own solar system and shedding light on the very nature of space and stars throughout the universe.
Together, NASA’s Parker Solar Probe and ESA’s (the European Space Agency) Solar Orbiter may resolve decades-old questions about the inner workings of our nearest star. Their comprehensive, up-close study of the Sun has important implications for how we live and explore: Energy from the Sun powers life on Earth, but it also triggers space weather events that can pose hazard to technology we increasingly depend upon. Such space weather can disrupt radio communications, affect satellites and human spaceflight, and — at its worst — interfere with power grids. A better understanding of the fundamental processes at the Sun driving these events could improve predictions of when they’ll occur and how their effects may be felt on Earth.
“Our goal is to understand how the Sun works and how it affects the space environment to the point of predictability,” said Chris St. Cyr, Solar Orbiter project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “This is really a curiosity-driven science.”
Parker Solar Probe is slated to launch in the summer of 2018, and Solar Orbiter is scheduled to follow in 2020. These missions were developed independently, but their coordinated science objectives are no coincidence: Parker Solar Probe and Solar Orbiter are natural teammates.
Read the complete article
#MAVEN measurements of a series of solar flares that erupted in September 2017 provided the first in situ data of #Mars’ upper atmospheric response to such an event.
Data from MAVEN’s suite of instruments revealed increased interactions between Mars’ ionosphere and thermosphere, and significantly higher than average O₂ atmospheric escape rates.
Read a related story in the American Geophysical Union (AGU)‘s EOS publication: http://bit.ly/2JfYbKJ.
To read the original related paper in Geophysical Research Letters, please visit: https://agupubs.onlinelibrary.wiley.com….
Laboratory for Atmospheric and Space Physics
University of Colorado Boulder
(Video credit: NASA Goddard)
Magnetic reconnection, one of the most important processes in the plasma-filled space around Earth, dissipates magnetic energy and propels charged particles, both of which contribute to a dynamic space weather system that scientists want to understand and someday predict. (NASA’s Goddard Space Flight Center/Joy Ng video)
The discovery will help scientists understand the role magnetic reconnection plays elsewhere in space, for example, in heating the inexplicably hot solar corona — the sun’s outer atmosphere — and accelerating the supersonic solar wind. NASA’s upcoming Parker Solar Probe mission will be launched directly toward the sun this summer to investigate exactly those phenomena, armed with this new understanding of magnetic reconnection near Earth.
And since magnetic reconnection occurs throughout the universe, what scientists learn about it around our planet — which is easier to examine — can be applied to other processes farther away.
“MMS discovered electron magnetic reconnection, a new process much different from the standard magnetic reconnection that happens in calmer areas around Earth,” said Tai Phan, a senior fellow in the Space Sciences Laboratory at the University of California, Berkeley. “This finding helps scientists understand how turbulent magnetic fields dissipate energy throughout the cosmos.”
Phan is lead author of a paper describing the findings that will be published this week in the journal Nature.
The complete article
Significant Space Weather Impact on the Escape of Hydrogen from Mars
Newly published MAVEN results indicate that atmospheric escape of hydrogen during a strong solar storm that impacted Mars in September 2017 was comparable to the seasonal escape of hydrogen over a full #Martian year.
Read the full publication in American Geophysical Union (AGU)‘s Geophysical Research Letters: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL077727.
Center for Space Physics at Boston University
UC Berkeley Space Sciences Lab | <urn:uuid:18878b6e-8fcc-4889-9a92-0eb8edff45fa> | 2.859375 | 1,692 | Content Listing | Science & Tech. | 30.366995 | 95,557,714 |
DNA-Folding by a Stably DNA-Linked Protein in Eukaryotic Chromatin
Higher levels of structural organization of DNA is achieved through its interaction with different proteins. These interactions are abolished by reagents destroying noncovalent associations, hydrogen bonding and S-S bridges. However, in chromatin of different origin a fraction of nonhistone proteins was found whose association with DNA could not be disrupted by such reagents (Lesko and Emery, 1966; Krauth and Werner, 1979; Neuer et al., 1983; Avramova and Tsanev, 1987). The presence of such a protein fraction was proved by in vitro iodination and by in vivo incorporation of labelled aminoacids. This firmly bound protein fraction showed several unusual properties: 1) After iodination it could not enter the Polyacrylamide gels upon electrophoresis. This made impossible the estimation of its molecular mass; 2) The two-dimensional tryptic peptide map of the iodinated protein isolated from eleven different chromatins — Drosophila, fish, frog and rat liver, chicken erythrocytes, rat and ram sperm, Guerin tumor cells, mouse Friend cells, maize leaves and roots — showed a practically identical pattern (Avramova et al., 1989a, b), revealing its high evolutionary conservation; 3) By in vivo labelling of DNA and of the protein it was found that this protein was metabolically stable, transmitted to the progeny like DNA (Avramova et al., 1988a); 4) Chemical and enzymic analysis of the DNA-protein linkage of the stable complex have suggested a bond of a phosphodiester type.
KeywordsProtein Fraction Nuclear Matrix Phosphodiester Bond Sperm Chromatin Chromatin Loop
Unable to display preview. Download preview PDF.
- Avramova Z., Mikhailov I., and Tsanev R. 1989, An evolutionarily conserved protein fraction stably linked to DNA in eukaryotic chromatin, Biochim. Biophys. Acta, 1007:109.Google Scholar
- Kleinschmidt A.1968, Monolayer techniques in electron microscopy of nucleic acid molecules in: ‘Methods in Enzymology’ 12B, L. Grossman and K. Moldave, eds., Academic Press, New York and London.Google Scholar
- Krauth W., and Werner D. 1979, Analysis of the most tightly bound proteins in eukaryotic DNA, Biochim. Biophys. Acta, 564:390.Google Scholar | <urn:uuid:5006cf4b-3ec4-42ee-a567-6c3809887895> | 2.53125 | 536 | Academic Writing | Science & Tech. | 37.920884 | 95,557,737 |
NASA's Aqua satellite passed over Extra-Tropical Storm Vongfong on Oct. 4 as it was moving away from Hokkaido, Japan, the northernmost of the big islands.
Vongfong transitioned into an extra-tropical storm early on Oct. 4 as its core changed from warm to cold.
The MODIS or Moderate Resolution Imaging Spectroradiometer instrument aboard NASA's Aqua satellite captured a visible image of Tropical Storm Vongfong over Japan on Oct. 14 at 03:15 UTC as it was southeast of the island of Hokkaido, Japan.
The image showed that south of the center of circulation was almost devoid of clouds and showers, which were all pushed to the north and east of the center as a result of southwesterly wind shear.
At 0300 UTC on Oct. 14, the Joint Typhoon Warning Center issued its final advisory on Tropical storm Vongfong.
At that time Vongfong's center was located near 29.1 north latitude and 142.9 east longitude, about 111 nautical miles (127.7 miles/205.6 km) southeast of Misawa, Japan.
Vongfong was moving to the northeast at a speedy 36 knots (41.4 mph/66.67 kph). Vongfong's maximum sustained winds were near 35 knots (40.2 mph/64.8 kph).
Vongfong had transitioned into an extra-tropical system and will continue to move away from northern Japan and over the northwestern Pacific Ocean.
NASA's Goddard Space Flight Center
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:09890494-5b5c-498c-9e53-df796d01b039> | 3.015625 | 908 | Content Listing | Science & Tech. | 49.092667 | 95,557,741 |
This was required by the scientists to be able to thoroughly investigate who or, more precisely, what is to answer for the greenhouse effect, from where oxygen, carbon dioxide and certain other gases are taken in the Earth’s atmosphere, what portion of the carbon dioxide can be absorbed by the Siberian bogs and forests and a mass of other questions which may at first sight appear to be trivial.
A truly amazing design is being constructed under a partner project between the International Science and Technology Centre and the Krasnoyarsk Sukachev Institute of the Forest SB RAS. The project is called "Response of Biogeochemical Cycles to Climate Change in Eurasia"and it will be accomplished by Russian researchers in cooperation with their German colleagues - specialists of the Institute of Biogeochemistry (Jena) and the Institute for Chemistry (Mainz). Both these institutes are a part of Europe’s largest scientific community, named after Max Planck.
However, the mast in itself is not unique. A twin-mast has been installed in Germany and it facilitates similar research, only not in forestland, like this Siberian one does, but in a region of exceptionally highly developed industry and agriculture. But together they will indeed provide a unique opportunity to compare the composition of the atmosphere in regions with fundamentally different anthropogenic load and ascertain how and due to what the composition changes. As a result, the atmospheric composition can be analyzed, or more precisely – the concentration within it of the most important gases (from the point of view of this research) at different altitudes, right up to 300 meters. Here it will be possible to study not simply the chemical but also the isotopic composition. And this will be the key to reveal the contribution of anthropogenic and natural components in the overall gaseous exchange flow in the atmosphere.
Project Manager Sergei Verkhovets explained in the most general terms why it was necessary to build a tower of such a height and how the isotopic composition of gases will help to determine their origin.
Measurements of CO2 concentrations at a height of 200 to 300 meters above the earth’s surface allow us to investigate the relatively homogeneous part of atmosphere, the so-called mixed layer. With that we can study the processes taking place over a vast territory, avoiding the "noise" caused by daily changes in the photosynthesis process close to the surface of the Earth.
As far as the isotope ratio in CO2, CH4, CO and N2O, and the ratio of O2/N2 are concerned, they make it possible to distinguish various carbon emission- and sink processes - photosynthesis and respiration of the ground-based biosphere, burning of fossil combustibles, and atmospheric-oceanic exchange and absorption.
For example, plants not only absorb ??2 in the course of photosynthesis; they also emit it while breathing. So, the carbonic acid gas "expired" by plants is enriched by a lighter isotope 12?. And above the ocean, where gaseous exchange processes obey to a greater extent physical rather than biochemical laws, the difference in isotopic composition is substantially equalized. Thus, if two air samples are taken and ??2 is isolated from them, and the isotopic composition is determined, its origin can be determined. The isotopic trace (signature) of a fossil combustible is also well-known. Carbon monoxide (CO), in its turn, bears information about anthropogenic emissions, because one of its main sources is the incomplete burning of fossil combustibles. A change in the correlation of 18O/16O in atmospheric CO2 helps to evaluate and isolate the respiratory flow from photosynthesis in Siberia. Continuous measurements of C16O18O on the continents are needed to reveal the climatic influence on carbon sink. Methane observations will help us better understand the connection between the climate and the ecosystem: from change in the concentration of "regular" and "heavy" methane 14CH4, researchers can track the respiration of peat bogs and, perhaps, of permafrost soils as well.
The data obtained in the course of observations will be the basic data for the construction of carbonic balance models both at regional and continental levels.
This task is especially topical for Russia. Owing to the adoption of the Framework Convention and the Kyoto Protocol, a situation has arisen whereby Russia can not only contribute to researching global climate change, but it can also gain significant economic benefits. The protocol stipulates that carbon dioxide removal from the atmosphere by natural absorbent ecosystems is rated as fulfillment of emission reduction ratings. The forests of Siberia constitute one fifth of the entire forests of the world, in terms of area at least. However, we need to know exactly what their capacity is in terms of an atmospheric carbon absorber. This project will make it possible to obtain data of this kind.
Andrew Vakhliaev | alfa
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
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Dry landscapes can increase disease transmission
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:71a12a65-35e9-4512-8e17-bcc800a26069> | 3.375 | 1,597 | Content Listing | Science & Tech. | 33.212797 | 95,557,742 |
|ECHINODERMATA : DENDROCHIROTIDA : Cucumariidae||STARFISH, SEA URCHINS, ETC.|
Description: A brown epifaunal sea cucumber with a smooth skin and 10 small tentacles. In larger specimens the tube-feet are in five double rows but a small, apparently neotenous form (called Ocnus brunneus) is known which looks exactly like Ocnus lactea but is brown. The two species often occur together. The spicules are knobbly but have more than 4 holes. Up to 8cm, neotenous form 1cm.
Habitat: Not well-defined but apparently epifaunal on algae, shells, worm-tubes and other sessile invertebrates in sheltered sites.
Distribution: Western coasts of the British Isles, Irish Sea and Dogger Bank. Further distribution includes the Mediterranean. Apparently the small neotenous form, which is believed to only reproduce by transverse division, has a more northerly distribution than the normal, sexually reproducing form. Confusion with Ocnus lactea has resulted in information about these species being mixed up.
Similar Species: See comments above about Ocnus lactea.
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). Ocnus planci (Brandt, 1835). [In] Encyclopedia of Marine Life of Britain and Ireland. |
http://www.habitas.org.uk/marinelife/species.asp?item=ZB4850 Accessed on 2018-07-16
|Copyright © National Museums of Northern Ireland, 2002-2015| | <urn:uuid:a4a7f800-7aba-4695-86d9-a47d56f68b8a> | 3.09375 | 399 | Knowledge Article | Science & Tech. | 40.131346 | 95,557,752 |
From August 2015 to September 2016, monthly readings of the following physiological characteristics were taken: quantum efficiency (Fv/Fm), maximum quantum yield of photosystem
II (PSII) ([Y.
In the most widely accepted model, temperature and/or light stress generate ROS in Symbiodinium chloroplasts through backup of excitation energy at photosystem
II; this may occur through damage to the water-splitting D1 protein of photosystem
II, reduced photosystem
repair, or inhibition of the dark reactions of photosynthesis (Douglas, 2003; Takahashi et al.
Cold and heat reduced photosynthesis efficiency: The photosystem
II (PSII) is a large pigment protein complex in thylakoid membrane that performs the vital reactions of photosynthesis.
It is suggested that maintaining a higher Fv'/Fm' as a protective mechanism of the photosystem
from photo-inhibitory damage which may lead to the repossession of photosynthesis after the plant is recovered from water stress.
0]) can be attributed to an inhibition of the flux of electrons to the oxidant site of photosystem
Data regarding the effective quantum yield of photosystem
II ([DELTA]F/Fm), non-photochemical quenching (NPQ), electron transport rate (ETR) and photochemical quenching (qP) did not differ between the plantlets cultured at different PPFDs.
To evaluate the effects of fluoride on the photosystem
II (PSII) operation, parameters of chlorophyll a fluorescence were measured before the beginning of the simulations (day 1) and 24 hours after the end of the experiment (day 11).
m] is an effective parameter to monitor the efficiency of light utilization by the algae as well as to assess the efficiency and stability of the photosystem
II (PSII), a major component of the photosynthetic machinery .
The holes of this wireless current are captured by the oxygen involving complex photosystem
to oxidize water oxygen.
Several studies have shown that photosystem
II (PSII) is often sensitive to UV-B and it has often been assumed to be the most sensitive photosynthetic target for UV-B.
In Pushkar's laboratory, students extracted a protein complex called Photosystem
II from spinach and after they excited them with a laser and records changes in the electron configuration of their molecules.
Temperature stress effects on photosynthetic rate are well documented in the literature, which was reported to negatively impact photosystem
II (PSII) (Strasser, 1997; Murata et al. | <urn:uuid:c36db3e0-a5a1-4def-9035-e96110701862> | 2.8125 | 539 | Knowledge Article | Science & Tech. | 11.605527 | 95,557,758 |
Full question is attached.
1) In this question we will consider the motion of a charged particle in uniform electric and magnetic fields that are perpendicular. You may ignore the effects of gravity throughout this question.
i) Consider a charged particle of mass m and charge q which is moving in a uniform electric field E = Eey and a perpendicular uniform magnetic field B = Bez. Show that the equations of motion for the particle are,
ii) If the particle is at rest at time t = 0, verify that
iii) Hence determine the position of the particle at time t, assuming that it was located at the origin at t = 0
b) An infinite metal plate occupies the xz-plane (y=0). The plate is kept at zero potential, V = 0. (see figure 1 below) Photoelectrons are liberated from the plate at y = 0 by ultraviolet radiation. The initial velocity of the photoelectrons is negligible. A uniform magnetic field B is maintained parallel to the plate in the positive z-direction and a uniform electric field E is maintained perpendicular to the plate in the negative y-direction. The electric field is produced by a second infinite plate parallel to the first plate, maintained at a constant positive voltage V0 with respect to the first plate. The separation of the plated is d.© BrainMass Inc. brainmass.com July 17, 2018, 7:26 pm ad1c9bdddf
The solution analyzes the motion of a particle in uniform electric and magnetic fields in detail. | <urn:uuid:3e50069f-c7a3-45b9-97bf-db58dd5b3787> | 3.46875 | 314 | Academic Writing | Science & Tech. | 49.481295 | 95,557,791 |
Mathematical physics is the study of mathematical methods for application of problems in physics. There are five distinct branches of mathematical physics: geometrically advanced formulation of classical mechanics, partial differential equations, quantum theory, Relativity and Quantum Relativistic Theories and statistical mechanics. Each branch has its own section of physics problems in which it corresponds to.
Mathematical physics is denoted by the nature of research. The research is aimed at studying and solving problems inspired by physics within a mathematically rigorous framework. Therefore, mathematical physics can cover a broad range of topics from pure mathematics to theoretical physics. Mathematical physicist does not conduct experiments like “regular” physicists do. The advent of the computer has created a new application of mathematical physics however that allows highly complex simulations being conducted. These simulations are run off of complex mathematical models to model certain phenomena.© BrainMass Inc. brainmass.com July 17, 2018, 7:21 pm ad1c9bdddf | <urn:uuid:1667841b-330f-4bd9-b34f-06a8c912cb93> | 2.890625 | 200 | Knowledge Article | Science & Tech. | 16.374019 | 95,557,792 |
Dixon's Q test
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In statistics, Dixon's Q test, or simply the Q test, is used for identification and rejection of outliers. This assumes normal distribution and per Robert Dean and Wilfrid Dixon, and others, this test should be used sparingly and never more than once in a data set. To apply a Q test for bad data, arrange the data in order of increasing values and calculate Q as defined:
Where gap is the absolute difference between the outlier in question and the closest number to it. If Q > Qtable, where Qtable is a reference value corresponding to the sample size and confidence level, then reject the questionable point. Note that only one point may be rejected from a data set using a Q test.
Consider the data set:
Now rearrange in increasing order:
We hypothesize that 0.167 is an outlier. Calculate Q:
With 10 observations and at 90% confidence, Q = 0.455 > 0.412 = Qtable, so we conclude 0.167 is indeed an outlier. However, at 95% confidence, Q = 0.455 < 0.466 = Qtable 0.167 is not considered an outlier. This means that for this example we can be 90% sure that 0.167 is an outlier, but we cannot be 95% sure.
McBane notes: Dixon provided related tests intended to search for more than one outlier, but they are much less frequently used than the r10 or Q version that is intended to eliminate a single outlier.
This table summarizes the limit values of the two-tailed Dixon's Q test.
|Number of values:|| 3
- Robert B. Dean and Wilfrid J. Dixon (1951) "Simplified Statistics for Small Numbers of Observations". Anal. Chem., 1951, 23 (4), 636–638. Abstract Full text PDF
- Rorabacher, D.B. (1991) "Statistical Treatment for Rejection of Deviant Values: Critical Values of Dixon Q Parameter and Related Subrange Ratios at the 95 percent Confidence Level". Anal. Chem., 63 (2), 139–146. PDF (including larger tables of limit values)
- McBane, George C. (2006) "Programs to Compute Distribution Functions and Critical Values for Extreme Value Ratios for Outlier Detection". J. Statistical Software 16(3):1–9, 2006 Article (PDF) and Software (Fortan-90, Zipfile)
- Shivanshu Shrivastava, A. Rajesh, P. K. Bora (2014) "Sliding window Dixon's tests for malicious users' suppression in a cooperative spectrum sensing system" IET Communications, 2014, 8 (7)
- W. J. Dixon. The Annals of Mathematical Statistics. Vol. 21, No. 4 (Dec., 1950), pp. 488-506 DOI: 10.1214/aoms/1177729747 | <urn:uuid:ed4dc931-8845-4d34-ac7b-763593eca0eb> | 3.703125 | 650 | Knowledge Article | Science & Tech. | 72.346649 | 95,557,793 |
Yet another application settings helper.
It's a common practice to put a settings file in a distribution package with some predefined stuff which can be overridden later in global project's settings. But there is also a good reason to separate all your settings within your apps just like you do so with common python code: models, views, etc. That's not a big thing if your project doesn't come with dozen apps, but if it does, flushing out non-project stuff is a good way to not mess things around and keep them way simple.
Lets say you have an email service application in your project dir and it stores some configuration in
MYEMAILSERVICE_USERNAME = 'username' MYEMAILSERVICE_PASSWORD = 'password' ...
It's a big temptation to write short
USERNAME, but you have to use prefixes to prevent conflicts with other application settings and tell collaborators this is for the email app. And then:
# emails/foo.py from django.conf import settings. service = Service(username=settings.MYEMAILSERVICE_USERNAME, password=settings.MYEMAILSERVICE_PASSWORD, ...)
Prefixes are everywhere. You always have to say
MYEMAILSERVICE_ in every single place you need to access the settings. How about this one:
# Package settings in emails/conf.py from pkgconf import Conf class MyEmailService(Conf): USERNAME = 'username' PASSWORD = 'password' @property def DEBUG(self): return self.USERNAME.startswith('test_')
There is nothing more to say:
# emails/foo.py # Note: your MyEmailService class becomes a module, # you import it directly from . import conf service = Service(username=conf.USERNAME, password=conf.PASSWORD, ...)
django-pkgconf wraps your application settings and provides a handy shortcut.
But what about test or dev settings? Just define them like you always do (configuration class name becomes a prefix).
# local_settings.py MYEMAILSERVICE_USERNAME = 'test_username'
Cool style (django-configurations way):
# settings.py class Prod(Configuration): # No email service settings at all pass class Test(Prod): MYEMAILSERVICE_USERNAME = 'test_username'
It looks for the required setting in django's configuration file first and returns original value if it's not overridden:
# emails/foo.py from . import conf conf.USERNAME # 'test_username' conf.PASSWORD # 'password' - returns original value conf.DEBUG # True
0.3.0 mixins are supported:
from pkgconf import Conf class FacebookMixin: FACEBOOK_APP_ID = 'foo' FACEBOOK_SECRET = 'bar' class TwitterMixin: TWITTER_APP_ID = 'foo' TWITTER_SECRET = 'bar' class InstagramMixin: INSTAGRAM_APP_ID = 'foo' INSTAGRAM_SECRET = 'bar' class SocialAppConf(FacebookMixin, TwitterMixin, InstagramMixin, Conf): DEBUG = True
Install the package:
pip install -U django-pkgconf
Read the quickstart.
Tested on py 2.7, 3.4, 3.5, 3.6 with django 1.8—2.1.
There are more advanced apps with (probably) some extra (better?) options: django-appsettings, django-appconf, etc. The reason I've published this one is those apps are too big and tricky to do this little work, so you might prefer them instead.
- Due to the code simplicity,
propertydescriptor is used to get data from the settings. That means you can not set (or change) configuration values in action. I don't know why you would do that, but I have to warn you.
- Since your app's settings are defined in separate file, they are not accessible via
django.conf.settings(until you override them in your project settings). This application doesn't create backward compatibility links. You should always use package configuration module.
- Added mixins support.
v0.2.1 - 0.2.2
__prefix__is generated automatically if not presented in class. That may help to build graceful exceptions like
'foo_value' was not found in MYAPP_FOO_SETTING.
__prefix__attribute to support prefix-names with underscores.
- Added instance method and property support.
- Backward incompatible change: functions must have
selfas the first argument now.
- First public release | <urn:uuid:5e333c87-15e6-4bc4-8fc3-88b23e6007b0> | 2.578125 | 1,011 | Documentation | Software Dev. | 45.116939 | 95,557,794 |
Html5 books 2018 → The software and code practices used for web application growth are getting sophisticated, and it’s nearly replacing the desktop applications. In this article, we give you the List of Top 10 Best HTML5 Books To Learn Web Design. Learn How to Code in HTML5 and CSS3 with the help of these books? What is the best reference book for HTML5 and CSS3? Which is the Best actual book for HTML5 and CSS3? below we listed HTML5 Books 2017 and HTML5 Books 2018.
10 Best HTML5 Books For Beginners
HTML5: Up and Running
9.5 out of 10
Head First HTML5 Programming
9.4 out of 10
HTML5 for Masterminds
9.3 out of 10
Introducing HTML 5
9.3 out of 10
HTML5: The Missing Manual
9.2 out of 10
HTML5 Solutions: Essential Techniques for HTML5 Developers
9.2 out of 10
The Definitive Guide to HTML5
9.1 out of 10
HTML5 Guidelines for Web Developers
9.1 out of 10
HTML5 Games Development by Example: Beginner’s Guide
9.0 out of 10
Dive Into HTML5
8.9 out of 10
Also Read: Top 10 Best Hacking Books For Learn Hacking
What is HTML5?
HTML5 is a markup language used for structuring and presenting content on the World Wide Web. It is the fifth and current version of the HTML standard. It is a is a latest and most enhanced version revision of the Hypertext Markup Language (HTML), the standard programming language for describing the contents and appearance of Web.back to menu ↑
Introduction of HTML5
HTML5 is the doc which is transmitted in text/ HTML MIME type, and internet browsers process it. The version 5 of HTML was known as HTML5. The newest version of HTML has many benefits over earlier versions. It helps audio and video playback without the use of plug-ins. The code of HTML5 requires new structural parts for creating the web page template as in comparison with traditional ‘div’ tags. It offers better and clearer code to developers and engineers. The brand new options of the code additionally provide local information storage, and the data may be accessed via web applications. Read Also: Best Laptops for programming 2018 List
The access may even be disconnected for a short while period. The development price of introducing the new components allows the developers to boost interoperability, whereas handling the elements. Finally, it helps in saving cost and time of the developer. The new options of HTML also present great assist for mobile devices. New type elements have been added to the overall structure to make sure the information entered via the form elements is correct and valid. The speed of loading the shape has additionally been improved within the new version. Read Also: Top 10 Best Java programming books for beginners
The access may even be disconnected for a short while period. The development price of introducing the new components allows the developers to boost interoperability, whereas handling the elements. Finally, it helps in saving cost and time of the developer. The new options of HTML also present great assist for mobile devices. New type elements have been added to the overall structure to make sure the information entered via the form elements is correct and valid. The speed of loading the shape has additionally been improved within the new version. Read Also: How to Create A Website Without Coding Skillback to menu ↑
Why You need HTML5 Books To Learn Web Design?
The new feature of HTML5 promotes simple, cost-efficient and effective coding practices. It offers advantages from developmental as well as finish-user perspective. These new features of HTML5 are revolutionizing the web and providing a simple encoding atmosphere to developers. A few of the most valuable HTML5 learning sources for front-end engineers/ developers are as follows:back to menu ↑
Listed Best HTML5 Books For Beginnersback to menu ↑
HTML5: Up and Running | Best Html5 Book EverBuy Now
Continue Next ↓back to menu ↑
Head First HTML5 Programming | Excellent Html5 BookBuy Now
HTML5 for MastermindsBuy Now
Must Read: Best PHP and MySQL Books For WEB DESIGNERSback to menu ↑
Introducing HTML 5Buy Now
HTML5: The Missing ManualBuy Now
HTML5 is greater than a markup language—it is a dozen independent web requirements all rolled into one. Till now, all it has been missing is a guide. With this thorough, jargon-free guide, you will learn how to construct web apps that include video tools, dynamic drawings, offline web apps, geolocation, drag-and-drop, and lots of different features. HTML5 is the future of the Web, and with this book, you will reach it shortly.
Recommended: Best Hacking Book to be a Good Hackerback to menu ↑
HTML5 Solutions: Essential Techniques for HTML5 DevelopersBuy Now
Web designers & developers now have a whole host of latest techniques up their sleeves, by displaying audio and video natively in the HTML code, creating real-time graphics directly on the internet page without the necessity for a plugin. But all of those new technologies bring additional tags to study and further avenues for things to go incorrect. HTML5 Solutions offers the lot of options for most common problems in HTML5. Every solution includes sample code that’s production-ready and will be applied to any project.back to menu ↑
The Definitive Guide to HTML5Buy Now
The next a part of the book covers the related W3C APIs that surround HTML5 specs. You’ll get an absolute working knowledge of the geolocation API, the communications API, web storage, &new drag and drop functionality.
The Ultimate Guide to HTML5 then dives into the key media enhancements of HTML5 code &its surrounding technologies: SVG, Canvas, audio, &video. The book rounds off with a high-stage coverage of programming, offline applications, security, testing &debugging HTML5.back to menu ↑
HTML5 Guidelines for Web DevelopersBuy Now
In HTML5 Guidelines for Web Developers, two pioneering web developers present a complete guide to HTML5’s very efficient with the new elements and methods through short, practical, very simple-to-understand examples. You will learn simply how much you can do with HTML5 Language —from programming audio/video playback to integrating geographical data into pages & applications.
HTML5 Games Development by Example: Beginner’s GuideBuy Now
The book will present you the way to use the latest HTML5 &CSS3 web requirements to build physics games, card games, drawing games, &even multiplayer games over the community. With this book, you’ll build six example games through step by step tutorials.
The book divides into entire nine chapters with each focusing on one subject/topic. We’ll create six games in book &mainly find out how we draw game objects, animate them, including the audio, be connecting gamers and building physics game with a Box2D physics engine.back to menu ↑
HTML5 Games | Creating Fun with HTML5, CSS3 and WebGLBuy Now
Discover new alternatives for building a 2D and 3D games with the HTML5 code.
Few More additionals HTML5 Booksback to menu ↑
HTML5 for Publishers (Free Kindle Edition)
The e-book offers text and graphics associated codes. It provides examples to make use of canvas, audio, video, and geolocation. It gives demos and graphics calculator via using canvas. It provides explanations related to finger painting application for drawing pictures and, besides, a demo on the way to customize the data and permit readers to know the present location. Embedded video and audio enabled glossary can also be provided. The explanation and the examples are given within the e-book are clear, and the author permits certain code to be reused without permission.back to menu ↑
Dive Into HTML5
This is a free online, complete tutorial of some popular, selected HTML5 features and different associated standards.back to menu ↑
HTML Dog is a social website containing HTML5 and CSS detailed tutorials, instance code, and articles.back to menu ↑
With the viable competitors in web designing, web designers and engineers require options which might improve the capability of a website without a lot effort and at a low-cost. Overall, HTML5 and CSS3 together provide the services that can be utilized by the web developers to extend their abilities.
Hope You Love The Article “Top 10 Best HTML5 Books To Learn Web Design” Keep Tuned For More Updates. | <urn:uuid:88397aac-f914-4835-be89-5edd66506920> | 2.796875 | 1,795 | Listicle | Software Dev. | 53.162365 | 95,557,799 |
Sun Not Only Detrimental To Skin
News Apr 26, 2018 | Original Story from the American Chemical Society.
Oil spills, whether minor leaks or major environmental disasters, are bound to happen. Chemical dispersants are one of the tools that can help mitigate the impact of such spills, but they become less effective as oil weathers in the environment. Now, one group reports in Environmental Science & Technology Letters that sunlight has a much greater impact than previously thought on the effectiveness of these dispersants.
According to the U.S. Environmental Protection Agency, 10-25 million gallons of oil spill each year in the U.S. In large marine oil spills, chemical dispersants are often used. Dispersants break up floating oil into small droplets, which can be eaten by microbes or fall onto the soil at the bottom of the body of water, decreasing the risk of oil accumulation on shorelines. As spilled oil floats on the water’s surface, it undergoes weathering processes, such as evaporation and emulsification, in which the oil forms a temporarily stable mixture with water, making chemical dispersants less effective. These are the major processes currently taken into account in field manuals and oil spill response guides for responders. According to these resources, photochemical oxidation, or chemical changes to the oil in response to sunlight, is a minor factor. However, in recent research, Collin P. Ward and colleagues determined that photochemical oxidation is a dominant weathering process. Now, these researchers wanted to examine how sunlight impacts the effectiveness of dispersants.
In the laboratory, the researchers analyzed samples of oil from the Macondo well, which was the location of the Deepwater Horizon spill in 2010. They confirmed that simulated sunlight has a larger impact on the oil’s properties than evaporation. In addition, dispersant effectiveness or performance decreased four-fold more when oil was exposed to sunlight than it did when the oil underwent evaporation in the absence of sunlight. To examine effects in the field, the team combined their estimates of how fast sunlight oxidizes oil with speeds of oil floating in the Gulf of Mexico and the locations of 412 aerial applications of dispersants on the Deepwater Horizon spill. Based on these data, the researchers say that many of the applications targeted oil that had undergone photochemical oxidation that lowered the dispersant effectiveness below 45 percent, which is below the threshold set by EPA for dispersants to be used in a spill. The team recommends that the effects of sunlight be considered in future field manuals and oil spill response guides for responders.
This article has been republished from materials provided by the American Chemical Society. Note: material may have been edited for length and content. For further information, please contact the cited source.
Photochemical Oxidation of Oil Reduced the Effectiveness of Aerial Dispersants Applied in Response to the Deepwater Horizon Spill. Collin P. Ward, Cassia J. Armstrong, Robyn N. Conmy, Deborah P. French-McCay, and Christopher M. Reddy. Environ. Sci. Technol. Lett., DOI: 10.1021/acs.estlett.8b00084.
Getting to Know the Microbes that Drive Climate ChangeNews
A new understanding of the microbes and viruses in the thawing permafrost in Sweden may help scientists better predict the pace of climate change.READ MORE
Perinatal Exposure to Phthalates Results in Lower Number of Neurons and Synapses in the Medial Prefrontal CortexNews
Phthalates - chemicals used in plastics belonging to the same class as Bisphenol A (BPA) - can potentially interfere with hormones important for the developing brain.READ MORE
Rocky Planet Neighbour Looks Familiar, but is Not Earth's TwinNews
Last autumn, the world was excited by the discovery of an exoplanet called Ross 128 b, which is just 11 light years away from Earth. New work has for the first time determined detailed chemical abundances of the planet’s host star, Ross 128.READ MORE | <urn:uuid:9a3b7c42-08bd-4706-8c15-ab262b246248> | 3.359375 | 832 | Truncated | Science & Tech. | 41.135545 | 95,557,802 |
H2 Mathematics Textbook
by Yan Min Choo
Number of pages: 1384
Includes 300 exercises and all 2006-2015 A-level exam questions -- all worked solutions included. Brief contents: I. Functions and Graphs. II. Sequences and Series. III. Vectors IV. Complex Numbers. V. Calculus. VI. Probability and Statistics.
Home page url
Download or read it online for free here:
by Joseph William Mellor - Longmans, Green
Long a standard textbook for graduate use in both Britain and America, this 1902 classic of modern mathematics remains a lucid, if advanced introduction to higher mathematics as used in advanced chemistry and physics courses.
by Steven G. Krantz - arXiv.org
This is a tract on the art and practice of mathematical writing. Not only does the book cover basic principles of grammar, syntax, and usage, but it takes into account developments of the last twenty years that have been inspired by the Internet.
by Peter J. Mitas - Quick Reference Handbooks
This handbook, written by an experienced math teacher, lets readers quickly look up definitions, facts, and problem solving steps. It includes over 700 detailed examples and tips to help them improve their mathematical problem solving skills.
This book is about the topic of mathematical analysis, particularly in the field of engineering. This will build on topics covered in Probability, Algebra, Linear Algebra, Calculus, Ordinary Differential Equations, and others. | <urn:uuid:c91dd539-9d67-439c-b04d-0463d9000864> | 2.71875 | 308 | Content Listing | Science & Tech. | 47.453317 | 95,557,811 |
You are a scientist working on a large protein (500 amino acids long) you have genetically engineered the protein in in such a way as to replace a single hydrophobic amino acid with a negatively charged amino acid. How might this substitution alter the primary and the tertiary structure of the protein? How will the nutritional value of the protein change? Make sure you explain the difference between primary and tertiary structures?© BrainMass Inc. brainmass.com July 18, 2018, 6:32 pm ad1c9bdddf
Primary structure refers to the amino acid chain that makes up the protein. It is coded for by the mRNA and formed during translation.
Secondary structure reflects the more complex 3-D structures that a string of amino acid can take. Secondary structures include alpha helices and beta sheets. They are formed by hydrogen bonds and van der Waals forces in regions of the protein.
Tertiary structure is the form the protein takes after all the ...
Definition of primary, secondary and tertiary protein structure as well as a discussion on the consequences of altering the primary protein structure. | <urn:uuid:0323b1cb-1962-4280-b7fc-b1dbce924584> | 3.609375 | 224 | Truncated | Science & Tech. | 45.485676 | 95,557,814 |
VB .NET Language Fundamentals
The minor mission of this chapter is to survey core syntactic changes that have been introduced to the Visual Basic programming language with the advent of VB .NET. As you will see, a number of language constructs used in earlier versions of VB have been cleaned up, removed, and improved, to produce a more consistent and elegant programming language. However, the main thrust of this chapter is to introduce you to the core aspects of the VB .NET language, including value-based and reference-based data types, the System.Object base class, and basic class construction techniques. Along the way, you also learn how to manipulate modules, strings, arrays, enumerations, and structures.
KeywordsBase Class Reference Type Object Instance Hash Code Object User
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A new study finds that human activities are likely contributing far less nitrogen to the open ocean than many atmospheric models suggest. That's generally good news, but it also nullifies a potential side benefit to additional nitrogen, says Meredith Hastings, associate professor of Earth, environmental and planetary sciences at Brown University and one of the study's co-authors.
"People may not be polluting the ocean as much as we thought, which is a good thing," said Hastings, who is also a fellow at the Institute at Brown for Environment and Society. "However, additional nitrogen could potentially stimulate the ocean's ability to draw down carbon dioxide out the atmosphere, which might counteract carbon emissions to some extent. But if we're not adding as much nitrogen, we're not getting that potential side benefit in the carbon cycle."
The research is published online in Proceedings of the National Academy of Sciences.
Nitrogen is the most abundant gas in the atmosphere and a key ecological nutrient, supporting the growth of plants and providing a food source for microorganisms. But excess nitrogen in aquatic environments can cause overgrowth of algae and other aquatic plants, which can throw ecosystems out of balance. Large algal blooms, for example, can deplete waterways of oxygen, leading to mass fish kills and other problems.
But along with the problems, there's a potential upside to excess nitrogen. An influx of nitrogen into the oceans could stimulate the growth of phytoplankton and other photosynthetic organisms. Photosynthesis consumes carbon dioxide, so an increase in biological activity could increase the oceans' ability to draw down atmospheric CO2.
Humans pour tons of additional nitrogen into the atmosphere through the burning of fossil fuels and biomass. Some of that nitrogen is carried by the wind and deposited in the oceans, but just how much of it reaches the vast open ocean far from coastlines isn't clear. Some atmospheric models estimate that 80 percent of nitrogen deposition to the ocean can be traced to humans, which would represent a huge influx of new nitrogen.
"The models generally assume that the ocean is a passive receptor of nitrogen," Hastings said. "We wanted to find out if that's true or if the ocean itself might play a substantial role in emitting nitrogen. If the ocean is playing a role, then this nitrogen deposition isn't all new nitrogen, from the ocean's perspective. It's recycled."
For their study, Hastings and her colleagues looked at the concentration and composition of organic nitrogen in samples of air and rainwater taken on Bermuda over the course of a year. Bermuda, about 600 miles off the eastern U.S. coast, offers scientists a natural test bed for studying the origin of atmospheric pollutants. The weather over the island is dominated by different air masses at different times of year. For much of the year, tropical air blowing northward from the open ocean dominates. But in the winter, a shift in atmospheric pressure pulls in air masses from the continental United States. Those continental air masses bring a host of industrial and agricultural pollutants with them.
"We have these distinct air masses coming in at different times," Hastings said. "So we're able to separate what's coming from anthropogenic sources and what's coming from marine sources."
The study showed that rather than being correlated with the source of air masses, the concentration of aerosol nitrogen is much more tightly correlated to measures of biological activity in the surrounding ocean. As biological activity (measured by a metric called gross primary productivity) increases, so does the concentration of organic nitrogen found in air samples. The molecular makeup of those nitrogen aerosols is also consistent with a marine origin, the researchers found.
"These marine biological processes appear to be producing compounds that are reacting in the atmosphere to create this organic nitrogen," Hastings said.
Organic nitrogen in rainwater samples appeared to contain somewhat more of a human signature, but was still dominated by marine sources, the study showed. Taken together, the results suggest that the ocean plays a much more substantial role in recycling organic nitrogen than was previously thought and that the role of human-derived sources is overestimated in atmospheric models.
This new finding completes a nitrogen puzzle that Hastings and her colleagues have been trying to piece together over the last few years. Organic nitrogen is not the only source of nitrogen deposition to the oceans. In previous work, Hastings and her team studied oceanic deposition of two inorganic nitrogen-based compounds: nitrate and ammonium. Those studies suggested that while a significant portion of nitrate can be traced to human sources, most ammonium deposited in the ocean is, like organic nitrogen, largely recycled from marine sources.
Combining results from this new work and their previous work on inorganic nitrogen sources, Hastings and her colleagues estimate that about 27 percent of total nitrogen deposition in the open ocean is derived from human sources -- much less than the 80 percent suggested by atmospheric models. That has implications for the idea that nitrogen pollution might help to counteract carbon emissions.
"If we're not putting as much new nitrogen into the open ocean, then we're not stimulating carbon drawdown," Hastings said. "So the impact on the carbon cycle is diminished."
The findings also suggest that more work needs to be done to better represent nitrogen deposition in atmospheric models.
"The models are clearly not getting this right," Hastings said. "We're lacking some understanding here, and that's really interesting to explore."
Other authors on the paper were Katye Altieri and Sarah Fawcett,University of Cape Town; Andrew J. Peters, Bermuda Institute of Ocean Sciences; and Daniel M. Sigman, Princeton University. The work was supported by the National Science Foundation and the National Oceanic and Atmospheric Administration.
Kevin Stacey | EurekAlert!
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine | <urn:uuid:224ef74f-3878-45ae-8ade-91caa118ece8> | 4.09375 | 1,786 | Content Listing | Science & Tech. | 36.618153 | 95,557,840 |
A new method of stress analysis in earthquake research has been developed by FOI, the Swedish Defense Research Agency. The method is a breakthrough for better earthquake warnings.
The new method of analysis makes it possible to estimate the complete stress tensor and monitor changes in the magnitude of stress and the instability of faults, which roots the analysis in physics in a manner that earthquake methods normally lack. This makes the method more generally valid, thus facilitating efforts to provide warnings.
Another advantage of the new method is that it makes use of micro-tremor data, that is, data for quakes with a magnitude of between -1 and 5, which offer the greatest possible amount of information for the analysis. Tests with Icelandic micro-tremors from 1990 to 2005 yielded excellent results, with the major earthquakes occurring precisely when they were predicted by the stress analysis. This experience from Iceland therefore indicates that the sites of coming earthquakes can be determined years before they occur.
"What is crucial to whether the analysis is reliable is to what extent the small quakes are analyzed," says the scientist behind the method, Ragnar Slunga.
"Especially if the method is to be used to warn people immediately before a coming earthquake, a few days or a few hours before the quake, it's necessary to analyze very minor micro-tremors as well," Slunga continues.
The Icelandic seismological network where the metering took place started as a Nordic collaborative project in 1988 and has continued as the largest EU project devoted to earthquake warnings. In 2006 the network comprised some 45 metering stations covering most of Iceland. The number of micro-tremors analyzed was about 250,000.
For more information, please contact: Ragnar Slunga, researcher and senior scientist, FOI, phone: +46 8-5550 3603; e-mail: email@example.com
Anna Kristiansson | idw
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
20.07.2018 | Materials Sciences | <urn:uuid:eb287f9f-5730-4279-8e05-bc08d5917c4c> | 3.515625 | 964 | Content Listing | Science & Tech. | 37.938314 | 95,557,841 |
Introduction to web development with Python and Django
Django was created in 2003 in a news agency, Lawrence Journal-World, which was to develop complete websites in very short time (hence the idea of the framework). In 2005, this agency decided to offer Django to the general public, deeming it mature enough to be reused anywhere. Three years later, the foundation Django Software is created by the founders of the framework in order to be able to maintain this one and the very active community which surrounds it.
Table of contents
- Http and the Request / Response cycle
- The Client Server Architecture
- Take Away
- Project folder
- Installing Django
- Creating Django project
- Creating the Database
- Inspecting the Database
- Running the server
- Creating & installing the Blog App
- Creating Web Services
- GET parameters
- File Size:
- 320.34 Kb
- Submitted On:
Take advantage of this course called Introduction to web development with Python and Django to improve your Web development skills and better understand Django.
This course is adapted to your level as well as all Django pdf courses to better enrich your knowledge.
All you need to do is download the training document, open it and start learning Django for free.
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Learning Website Development with Django
A beginner's PDF tutorial to building web applications,quickly and cleanly, with the Django application framework by Ayman Hourieh. | <urn:uuid:381ed054-51f0-490a-9b77-df2ef0e9a9fe> | 2.828125 | 452 | Product Page | Software Dev. | 39.690462 | 95,557,859 |
The Diffuse Vent Fluid 3-D Temperature Array measures temperatures of diffuse flow across the seafloor. The thermistor array is designed as 4 stacked triangular arrays with 24 independent temperature measurement points, providing a three-dimensional distribution of temperature. Moderate- to low-temperature hydrothermal fluids exiting diffuse flow sites on Axial Volcano support communities of animals that include limpets, tubeworms, scale worms, clams, and Pycnogonida, an arthropod that resembles a spider. Critical to understanding how these communities thrive, evolve, and expire are long-term measurements of fluid temperature and chemistry, coupled with direct imagery.
A custom thermistor array, developed by UW Project Scientist, Giora Proskurowski, is designed to measure the 3-dimensional distribution of temperatures within a diffuse flow site. Within the four layers of blue cable, there are 24 places where temperatures will be continuously measured. When installed at the base of a hydrothermal chimney within the ASHES hydrothermal field at the summit of Axial Volcano, the cabled thermistor array will provide a real-time 3-dimensional “view” of the temperature structure at this site. Such data will provide information about the environmental conditions within which the biological assemblages thrive and evolve. Other installations at this site include an osmotic sampler, to determine the temporal evolution of fluids, and a high-definition video camera, to study fluid velocities and the evolution of animal and microbial communities within the context of evolving environmental conditions (e.g. earthquakes, lunar tides, eruptions).
This instrument measures the following data products. Select a data product's name to learn more.
|Temperature Array in Spatial Grid||TEMPSFL||DPS|
Instrument Models & Deployed Locations
The OOI includes the following instrument makes and models for this instrument type. Follow the links below to find out where in the OOI this instrument has been deployed. You'll also find quick links for each instrument to Data portal, where you can plot and access data.
Primary Science Discipline
TMPSF on the Data Portal | <urn:uuid:823817b4-9d3b-463a-ac02-b3e916492945> | 2.640625 | 443 | Knowledge Article | Science & Tech. | 18.454285 | 95,557,880 |
Why we accidentally slow-down people on the motorway and lose football matches
Movement and orientation in space is an everyday experience. But it is also a fundamental theoretical problem for science. How does a moving observer perceive the relative movement between two other persons or objects? Despite its everyday relevance, this "perceptual three-body problem" is largely unexplored.
Dr. Tobias Meilinger from the department of Prof. Bülthoff at the Max Planck Institute (MPI) for Biological Cybernetics and Dr. Bärbel Garsoffky and Prof. Dr. Stephan Schwan from the Leibniz Institute for Knowledge Media (IWM) examined under which circumstances the perception of movement is distorted - and thus an illusion arises.
The experiment: A human being in motion. While the person is walking, she/he watches two other people. One seems to be following the other. The question to the observer: Can the persecutor catch up with the person pursued? The special feature of the study is the combination of two sources of movement – one’s own and the movements of two targets in the environment.
This is when we are talking about a triangular relationship which has a decisive influence on the observer's perception - and thus also on conclusions and decisions. Also in assessing whether the pursuer can catch up. Under certain circumstances, this leads to a distorted perception and thus misjudgment - in other words, an illusion arises.
Caption: An observer sees two runners moving away from her/him. Due to a distortion of perception, the rear appears to be faster than it is in reality – a catching-up illusion arises.
The result of the investigation: To assess the relative movement away from or towards an observer, the perception is often distorted - either a catch-up or a fallback illusion is created. In other words, depending on the observer's own speed, the pursuer seems to either reach the persecuted person or fall back. The scientists showed that these illusions arise from a changed perception of distance. Just as the dashed centerlines on a road seem to be shorter the further away they are, and the longer the closer they are. This also changes the perceived distance between two runners and thus the illusion if and when they catch up with each other.
But how does the illusion affect everyday life? Let's take two examples of perception from driving a car and football games. On the motorway: I'm driving on the left-hand lane of the motorway. Two cars are driving on the right-hand lane. The question: Can I foresee that the rear one wants to change to my lane? My assessment is influenced by the fact that I drive fast myself. I don't notice that the rear car accelerates, because the fallback illusion hides that.
The driver, however, starts to overtake, comes onto my track and slows me down. The distortion of her/his distance to the front car causes me to underestimate its true speed. A similar case on the football field: The striker from my team dashes to the opponent's goal, followed by an opposing player. I myself follow slower and want to play her/him the ball, but I overestimate the speed of the catching-up opponent due to the illusion and therefore I don't pass the ball on, missing the chance to score.
Whether on the street or on the football pitch, distortion of perception can lead to considerable disadvantages in both cases: I have to slow-down, the striker does not get the decisive pass. Possible countermeasures could be to point out to drivers or players that there is such a distortion and thus misjudgment.
Or: teach autonomous cars to take into account human perception distortion to prevent dangerous situations. Or: speed limits on motorways. In this way, the strong differences in speed variances that lead to distortion of perception can be avoided.
Please read an interview about the study with Tobias Meilinger. (Link)
PD Dr. Tobias Meilinger
MPI for Biological Cybernetics
Telefon: ++ 49 (0) 7071 601 615
MPI for Biological Cybernetics
Head of Communications and Public Relations
Telefon: +49 (0) 7071 601-777
Leibniz-Institut für Wissensmedien
Telefon: +49 (0) 7071 979-222
Two runners move away from a static observer, keeping the same distance to each other. However, the pursuer seems to catch up and illustrates the uplifting illusion. The videos in the experiment ended after 1.5 seconds and the speed of pursuers and observers varied.
Copyright: Drawing and Video Clip: Tobias Meilinger/Max Planck Institute for Biological Cybernetics
Max-Planck-Institut for Biological Cybernetics
The Max Planck Institute for Biological Cybernetics works in the elucidation of cognitive processes. It employs about 300 people from more than 40 countries and is located at the Max Planck Campus in Tübingen, Germany. The Max Planck Institute for Biological Cybernetics is one of 83 research institutes that the Max Planck Society for the Advancement of Science maintains in Germany and abroad.
Leibniz-Institut für Wissensmedien
The Leibniz-Institut für Wissensmedien (IWM) in Tuebingen analyses teaching and learning with digital technologies. In a multidisciplinary environment, around 80 scientists from cognition, behavioural and social sciences work on solving research questions concerning individual and collective knowledge acquisition in media environments. Since 2009, the IWM and the University of Tuebingen jointly run Germany’s first Leibniz-WissenschaftsCampus “Informational Environments”.
Internet address: www.iwm-tuebingen.de.
Press release: http://tuebingen.mpg.de/en/news-press/press-releases/
MPI for Biological Cybernetics: http://www.kyb.tuebingen.mpg.de
Leibniz-Institut für Wissensmedien: www.iwm-tuebingen.de
Public Realtions Office | Max-Planck-Institut für biologische Kybernetik
Enzyme discovery could help in fight against TB
12.07.2018 | University of Warwick
MSU researchers lead team that discovers heaviest known calcium atom
12.07.2018 | Michigan State University Facility for Rare Isotope Beams
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...
Sizes and shapes of nuclei with more than 100 protons were so far experimentally inaccessible. Laser spectroscopy is an established technique in measuring fundamental properties of exotic atoms and their nuclei. For the first time, this technique was now extended to precisely measure the optical excitation of atomic levels in the atomic shell of three isotopes of the heavy element nobelium, which contain 102 protons in their nuclei and do not occur naturally. This was reported by an international team lead by scientists from GSI Helmholtzzentrum für Schwerionenforschung.
Nuclei of heavy elements can be produced at minute quantities of a few atoms per second in fusion reactions using powerful particle accelerators. The obtained...
12.07.2018 | Event News
03.07.2018 | Event News
28.06.2018 | Event News
12.07.2018 | Life Sciences
12.07.2018 | Physics and Astronomy
12.07.2018 | Earth Sciences | <urn:uuid:e53b399b-128d-4819-8ff3-1bed83157dab> | 3.046875 | 1,982 | Content Listing | Science & Tech. | 45.858351 | 95,557,890 |
In the SELECT clause, you can code an expression that include one or more arithmetic operators. An expression is a combination of column names, numbers ...
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From 1BestCsharp blog | <urn:uuid:2e1efada-37df-4fbb-a1d6-478ad0f2d0ca> | 2.828125 | 344 | Content Listing | Software Dev. | 51.385774 | 95,557,897 |
New Chandra images of Sagittarius A* (Sgr A*), which is located about 26,000 light-years from Earth, indicate that less than 1 percent of the gas initially within Sgr A*'s gravitational grasp ever reaches the point of no return, also called the event horizon. Instead, much of the gas is ejected before it gets near the event horizon and has a chance to brighten, leading to feeble X-ray emission.
X-ray: NASA/UMass/D. Wang et al., IR: NASA/STScI
One of the biggest observing campaigns ever performed by Chandra has provided new understanding into why gas near the giant black hole at the center of the Milky Way is extraordinarily faint in X-rays. The large image contains X-rays from Chandra (blue) and infrared emission from the Hubble (red and yellow). The inset shows a close-up of Sgr A* in X-rays only, covering a region half a light year wide. The diffuse X-ray emission is from hot gas captured by the black hole and being pulled inwards. The new results indicate that less than 1% of the material that is initially within the black hole’s gravitational grasp reaches the event horizon, or, point of no return.
These new findings are the result of one of the longest observation campaigns ever performed with Chandra. The spacecraft collected five weeks' worth of data on Sgr A* in 2012. The researchers used this observation period to capture unusually detailed and sensitive X-ray images and energy signatures of super-heated gas swirling around Sgr A*, whose mass is about 4 million times that of the sun.
"We think most large galaxies have a supermassive black hole at their center, but they are too far away for us to study how matter flows near it," said Q. Daniel Wang of the University of Massachusetts at Amherst, who led a study published Thursday in the journal Science. "Sgr A* is one of very few black holes close enough for us to actually witness this process."
The researchers found that the Chandra data from Sgr A* did not support theoretical models in which the X-rays are emitted from a concentration of low-mass stars around the black hole. Instead, the X-ray data show the gas near the black hole likely originates from winds produced by a disk-shaped distribution of young massive stars.
"This new Chandra image is one of the coolest I’ve ever seen," said co-author Sera Markoff of the University of Amsterdam in the Netherlands. "We're watching Sgr A* capture hot gas ejected by nearby stars, and funnel it in towards its event horizon."
To plunge over the event horizon, material captured by a black hole must lose heat and momentum. The ejection of matter allows this to occur.
"Most of the gas must be thrown out so that a small amount can reach the black hole", said co-author Feng Yuan of Shanghai Astronomical Observatory in China. "Contrary to what some people think, black holes do not actually devour everything that’s pulled towards them. Sgr A* is apparently finding much of its food hard to swallow."
The gas available to Sgr A* is very diffuse and super-hot, so it is hard for the black hole to capture and swallow it. The gluttonous black holes that power quasars and produce huge amounts of radiation have gas reservoirs much cooler and denser than that of Sgr A*.
The event horizon of Sgr A* casts a shadow against the glowing matter surrounding the black hole. This research could aid efforts using radio telescopes to observe and understand the shadow. It also will be useful for understanding the effect orbiting stars and gas clouds may have on matter flowing toward and away from the black hole.
NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.
Megan Watzke | Newswise
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:a1a79496-195d-4c6f-98a5-b5b32fdfd346> | 3.421875 | 1,478 | Content Listing | Science & Tech. | 48.516319 | 95,557,902 |
The transfer of water from phloem into xylem is thought to mitigate increasing hydraulic tension in the vascular system of trees during the diel cycle of transpiration. Although a putative plant function, to date there is no direct evidence of such water transfer or the contributing pathways. Here, we trace the radial flow of water from the phloem into the xylem and investigate its diel variation. Introducing a fluorescent dye (0.1% [w/w] fluorescein) into the phloem water of the tree species Eucalyptus saligna allowed localization of the dye in phloem and xylem tissues using confocal laser scanning microscopy. Our results show that the majority of water transferred between the two tissues is facilitated via the symplast of horizontal ray parenchyma cells. The method also permitted assessment of the radial transfer of water during the diel cycle, where changes in water potential gradients between phloem and xylem determine the extent and direction of radial transfer. When injected during the morning, when xylem water potential rapidly declined, fluorescein was translocated, on average, farther into mature xylem (447 +/- 188 mu m) compared with nighttime, when xylem water potential was close to zero (155 +/- 42 mu m). These findings provide empirical evidence to support theoretical predictions of the role of phloem-xylem water transfer in the hydraulic functioning of plants. This method enables investigation of the role of phloem tissue as a dynamic capacitor for water storage and transfer and its contribution toward the maintenance of the functional integrity of xylem in trees.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:da2595cd-48fc-4caf-90f8-74e3e54adcc1> | 3.21875 | 360 | Academic Writing | Science & Tech. | 25.109781 | 95,557,903 |
The Asian ladybird secretes a yellow, bitter poison (hemolymph) when in danger , which significantly reduces the number of its enemies.
|Asian lady beetle|
|The female of the species lays its eggs on plants that are infested by aphids. The larvae slip off after a few days and eat up to 1200 aphids during the two weeks of their development. The larva turns into a pupa on a leaf. After about one week the adult Asian ladybird slip off the pupa.|
At the production of wine the Asian lady beetle can be a problem. The hemolymph of the beetle affects the taste so dramatically, that the wine is unfit to drink.
Asian ladybirds are commonly found in populated areas, where they seek out (often in large numbers) apartments and houses to hibernate , and can thus be a pest.
|Further chapters of "Asian lady beetle"|
|Description of images / photos|
Photography with Cameras
Nikon D3x, Nikon D300, Canon 50D
Image editing with Photoshop
|1. ||Asian lady beetle - harlequin lady beetle|
|2. ||Asian lady beetle - Harmonia axyridis|
|3. ||Beetle - Harmonia axyridis - top view|
|4. ||Asian lady beetle|
|Harmonia axyridis (5)|
|harlequin beetle (2)|
|Asian multicolored lady beetle (2)|
|lady beetle (1)|
|beetle top view (1)|
|‘HARMONIA AxYRIDIS’ (1)|
|asian harlequin beetle (1)|
|photos of asian lady beetle (1)|
|what are grey with spots ladybirds called (1)| | <urn:uuid:55265fe3-c6d2-4615-95ad-1e0359a4dc3e> | 3.203125 | 380 | Knowledge Article | Science & Tech. | 45.533176 | 95,557,906 |
Since the speed of sound in water is much greater than that of the surface gravity waves, acoustic signals can be used for early warning of tsunamis. We simplify existing works by treating the sound wave alone without the much slower gravity wave, and derive a two-dimensional theory for signals emanating from a fault of finite length. Under the assumptions of a slender fault and constant sea depth, the asymptotic technique of multiple scales is applied to obtain analytical results. The modal envelopes of the two-dimensional sound waves are found to be governed by the Schrödinger equation and are solved explicitly. An approximate method is described for the inverse estimation of fault properties from the pressure record at a distant hydrophone.
Email your librarian or administrator to recommend adding this journal to your organisation's collection.
* Views captured on Cambridge Core between 11th December 2017 - 22nd July 2018. This data will be updated every 24 hours. | <urn:uuid:b3805b22-9f4a-42f0-ac57-7e06b8bcdda9> | 2.640625 | 189 | Truncated | Science & Tech. | 34.722927 | 95,557,975 |
WASHINGTON — NASA's new planet-hunting telescope has found two mystery objects that are too hot to be planets and too small to be stars.
The Kepler Telescope, launched in March, discovered the two new heavenly bodies, each circling its own star. Telescope chief scientist Bill Borucki of NASA said the objects are thousands of degrees hotter than the stars they circle. That means they probably aren't planets. They are bigger and hotter than planets in our solar system, including dwarf planets.
"The universe keeps making strange things stranger than we can think of in our imagination," said Jon Morse, head of astrophysics for NASA.
The new discoveries don't quite fit into any definition of known astronomical objects, and so far don't have a classification of their own. Details about the mystery objects were presented Monday at a meeting of the American Astronomical Society in Washington.
For now, NASA researcher Jason Rowe, who found the objects, said he calls them "hot companions."
How hot? Try 26,000 degrees Fahrenheit. That's hot enough to melt lead or iron.
There are two leading theories for what the objects might be and those theories cover both ends of the cosmic life cycle:
- Rowe suggests they are newly born planets. New planets have extremely high temperatures, and in this case Rowe speculates they might be only about 200 million years old.
- Ronald Gilliland of the Space Telescope Science Institute says they could be white dwarf stars that are dying and stripping off their outer shells and shrinking.
The primary focus of the Kepler telescope's three-year mission is to find out how common other planets — especially Earth-like planets — are in the universe. To do that, it is scanning a small chunk of the sky, about one four-hundredth of the night sky with more than 150,000 stars to look for planets.
The telescope in just six weeks found its first five confirmed planets, slightly more than astronomers expected from such a quick search. There are hundreds of other candidates that need confirmation.
The five planets are all much larger than Earth, much closer to their stars than Earth is to the sun, and way too hot for life, Borucki said. A couple of these planets are close to 3,000 degrees.
"Looking at them is like looking at a blast furnace," Borucki said. "Certainly, no place to look for life."
One of the newly discovered planets is so airy that "it has the density of Styrofoam," Borucki said.
"There's going to be all kinds of weird stuff out there," said Alan Boss of the Carnegie Institute of Washington, who wasn't part of the research. "This is an unparalleled data set. The universe really is a weird place. It's fantastic."
On the Net:
Kepler Telescope: www.kepler.nasa.gov | <urn:uuid:94bbc0eb-b441-49aa-ba28-9fd8767c2c61> | 3.5625 | 587 | News Article | Science & Tech. | 58.882411 | 95,557,997 |
The crystals grow in size as they join together, becoming heavy and then dropping down through the cloud. Although there are different crystal shapes, snowflakes are always six-sided, with some having six branches sticking out of the central core. Ice crystals formed in the appropriate conditions can often be thin and flat. Planar crystals (thin and flat) grow in air between 0 °C (32 °F) and −3 °C (27 °F). Between −3 °C (27 °F) and −8 °C (18 °F), the crystals will form needles. Snow remains on the ground until it melts. In colder climates the snow lies on the ground all winter; and when the snow does not all melt in the summer, they become glaciers. | <urn:uuid:188689f7-5634-4b6f-a9a6-d35090220782> | 3.875 | 155 | Knowledge Article | Science & Tech. | 80.097647 | 95,558,001 |
Management measures aimed at restoring commercial stocks of marine fish, for example cod, is an efficient tool to decrease eutrophication effects in coastal areas. This is the main conclusion of a new study reviewing over 50 experimental studies in the North Atlantic, being published in the Journal of Applied Ecology.
Across Europe, the value of our coasts is suffering from declines in ecosystem services provided by important and valuable species. In the Wadden Sea, long lived and commercial fish species such as dab, sole, cod and whiting have decreased dramatically. These are all larger predatory fish, which have an important function in the coastal ecosystem. They control the abundance of smaller fish and crabs, which indirectly have a significant impact on vegetation and on algal blooms.
At the same time, habitat-forming vegetation, such as eelgrass, has been declining. Eelgrass constitutes important habitats for marine organisms and acts as nursery grounds for many commercial fish species. However, eelgrass has largely disappeared from Dutch waters and decades of restoration efforts have failed.
Increased nutrient levels in the water, i.e. eutrophication, is one important cause of the decline of habitat-forming vegetation in Europe. Nutrients increase overgrowth of fast-growing often filamentous algae that smother the larger vegetation. However, it has been suggested that also overfishing of large predatory fish, such as cod, have resulted in more overgrowth and declines of the larger vegetation through so-called trophic cascades. When the larger fish decrease, their prey of small fish and crabs are allowed to increase. This, in turn, causes a decrease in their prey of herbivorous invertebrates that eat filamentous algae, resulting in more overgrowth.
Researchers at the Swedish University of Agricultural Sciences, Stockholm University, University of Gothenburg, and University of Groningen in the Netherlands have now systematically reviewed over 50 experiments conducted in the North Atlantic that have manipulated nutrient levels, abundance of invertebrate herbivores and different types of fish, to estimate how nutrients and coastal animals affect fast-growing ephemeral algae.
The results show that nutrients, mainly nitrogen, and predation from crabs and small fish on herbivorous invertebrates have similar positive effects on the growth of algae. Small fishes and crabs have increased in the coastal zone as a result of overfishing of large predatory fish that normally eat and control them. The implication is that weak stocks of predatory fish can have similar effects on blooms of filamentous algae as eutrophication.
A conclusion of this study is that measures aiming to restore commercial stocks of larger fish or reducing small fish and crabs could relatively quickly reduce the abundance of ephemeral algae and thereby benefit underwater vegetation such as eelgrass. Thus, a more natural fish community can contribute to both better water quality and healthier habitats in coastal areas, which highlights the advantages of an integrated, ecosystem-based management of coastal areas.
Text: Britas Klemens Eriksson, University of Groningen, Johan Eklöf, Stockholm University and Per-Olav Moksnes, University of Gothenburg
Reference: Top-down control as important as nutrient enrichment for eutrophication effects in North Atlantic coastal ecosystems. Örjan Östman, Johan Eklöf, Britas Klemens Eriksson, Jens Olsson, Per-Olav Moksnes and Ulf Bergström DOI: 10.1111/1365-2664.12654 Journal of Applied Ecology, 16 April 2016
RUG verleent eredoctoraat aan voormalig VN secretaris-generaal Ban Ki-moon
RUG op plek 39 in Europe Teaching Excellence ranking
De Wierenga-Rengerinkprijs voor de RUG-promovendus met de beste dissertatie in 2017, is toegekend aan dr. Alain Dekker voor zijn proefschrift ‘Down & Alzheimer: Behavioural biomarkers of a forced marriage’. | <urn:uuid:e64cf43d-9d1d-441b-98c9-81e49f439ecc> | 3.734375 | 837 | Academic Writing | Science & Tech. | 20.900686 | 95,558,016 |
The number of states is expressed as a function of various parameters for three systems below. For each, find an "equation of state" which gives the relationship between p, V, N, and T.
(C and b are constants.)
Please see the attached Microsoft Word document regarding specifics.© BrainMass Inc. brainmass.com July 20, 2018, 1:16 am ad1c9bdddf
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The solution is ...
The solution shows how to extract the equation of state from the expression of the micro-canonical partition function. | <urn:uuid:15cfc3f2-385e-4aa4-b8b9-cbd920ea7f12> | 2.546875 | 127 | Q&A Forum | Science & Tech. | 70.690455 | 95,558,053 |
By Melvin Bolton
Read or Download Conservation and the Use of Wildlife Resources (Conservation Biology) PDF
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They’re creepy when they buzz loudly past you towards light sources and produce an extremely pungent odor when disturbed, but stink bugs live their lives content to feed on plants and would rather not encounter you.
There are more than 200 species of stink bugs in North America. Adults are usually some shade of green, tan, or gray-brown.
After mating, the female lays batches of 20 to 30 eggs, depositing them on the underside of plant leaves. Her eggs look like tiny barrels and are light green in color to blend in with their surroundings and avoid predators. Sometimes the eggs are pearly white at first, turning pink later. On top of each egg is a circle of white projections.
A single female can lay up to 300 eggs in a single season.
The eggs hatch in four to five days, marking the beginning of the nymph stage. A small triangle on each egg shell is used by the nymph as a knife to cut the shell open. Stink bug nymphs usually remain gregarious for a short period of time after hatching, as they begin to feed and molt.
Peggy Whitson was born on February 9th, 1960 in Mount Ayr, Iowa. In 1981 she graduated from Iowa Wesleyan College with a Bachelor of Science degree in biology. Then, in 1985, she graduated from Rice University with a doctorate degree in biochemistry. After her graduation, she continued on at Rice as a post-doctoral fellow for another year.
Peggy Whitson spent a number of years working at NASA before she first went to space. In 1989, Whitson joined NASA as a research biochemist. She served in this role for three years before she became a technical monitor, a job she held from 1991 through 1992. Then, in 1992, she became the project scientist of the Shuttle-Mir Program. Whitson subsequently worked in NASA’s Medical Sciences Division and then became the co-chair of the U.S.-Russian Mission Science Working Group.
It was in August 1996 when Peggy Whitson began training to become an astronaut. This took two years, and her first mission was in 2002.
Whitson was a crew member on Expedition 5, which launched on June 5th, 2002. She was one of two flight engineers. She subsequently spent 184 days in space, also completing a 4 hour and 25 minute spacewalk. Then, in 2007, Whitson was a crew member on Expedition 16, and this time she spent 192 days in space.
Whitson shows how dreams become reality, becoming the first female commander of the International Space Station and serving a record 665 days in space. She served as commander twice and also holds the record for most space walks by a woman (10), most hours outside the vehicle (60) and oldest woman in space (57). She was supposed to return to Earth in June 2017 but happily accepted the opportunity to stay on another three months when Russia’s space organization Roscosmos pulled its crew back from participation in a mission to the ISS earlier that year.
Truly a NASA superstar Whitson encourages aspiring astronauts to get education in science, math and engineering.
Want more information? Watch this interview with Commander Whitson on Connections to Science from Iowa Public Television:
The spotted handfish is one of the world’s most endangered marine fish, having undergone a massive decline in recent decades.
Handfish grow up to 5” long, and have skin covered with tooth-like scakes, giving them the alternate name warty anglers. They get their name from the way they used their pectoral (side) fins like hands to grip the bottom. They rarely swim – they prefer to walk along the bottom on their fins feeding on small invertebrates.
Once relatively common, red handfish have become scarce in recent years, probably due to habitat loss and changing sea conditions.
Divers in Tasmania have discovered a new population of red handfish. The newly discovered colony could double their total population to 80 individuals.
This very rare red handfish has two color morphs – one a brilliant red with bluish and white fin margins, the other mottled pink with reddish spots and patches on the body and fins.
Threats to red handfish include poaching for use as pets. Also its low reproductive rate and low dispersal rate have raised fears of extinction.
Hopefully, the discovery of this second population means the red handfish has an alternative destiny ahead of it.
Here’s a short video by Michael Baron of two red handfish on the move:
Nineteenth-century naturalist, ornithologist, and artist John James Audubon lived the later years of his life in northern Manhattan, in what is now the Hamilton Heights neighborhood of Harlem. Audubon is best known for his comprehensive book, The Birds of America, which was accompanied by beautiful, detailed illustrations of many of the birds.
Today, visitors to Hamilton Heights will discover a series of amazing murals that honor Audubon while bringing attention to the effects of climate change on North America’s bird populations. Known as the Audubon Mural Project, the murals are a collaborative effort of the National Audubon Society and Gitler & ______Gallery (yes, that’s the gallery’s actual name – there is an underlined blank space).
This spray-painted menagerie graces roll-down gates and barren walls with permission of willing property owners. Here are a few examples:
Elsewhere, Audubon himself is rendered in flesh tones and with mutton-chop sideburns, staring curiously at a cerulean warbler on his shoulder with neither his rifle nor palette at hand.
The National Audubon Society’s website has a map showing the location of each mural. The website also serves as an excellent guide for a tour of the murals, as it gives much more information about each one, including an explanation of how the birds are being affected by climate change and some remarks by each artist about their art.
Leafhoppers, treehoppers and planthoppers have the most aerodynamic-shaped body in the insect world. All of them are strong jumpers that can move with equal ease forwards, backwards, or sideways like a crab. The crab-like motion distinguishes hoppers from most other insects.
They also come in many shapes and colors with over 12,500 varities worldwide.
The beautiful insect shown below is a planthopper nymph. During the span of time after it hatches and before it becomes fully mature, the planthopper nymph secretes a waxy substance from its abdomen that gives its tail the look of a colorful fiber optic display. It serves as a defense from predators who are somewhat hypnotized by the effect.
As the planthopper gets ready to do its favorite thing — hop around — it moves the waxy threads into a sleek line.
It moves ever so slowly before making a great leap, and it can fan the threads back out for an extra boost while it’s in the air.
The final effect is like a dazzling fiber options display.
The amazing photograph above shows splashes formed from single drops landing in puddles. Captured over several months, they were photographed in darkness using a high-speed flash to preserve their colors and shapes and then brought together in one image.
This winning photograph shows drops of glycerin and water impacting a thin film of ethanol. The difference in surface tension creates holes in the drop’s surface making it look like lace.
Another image created by Phred Petersen. This is a time lapse image showing the progress of an agaric toadstool mushroom as it grows.
Phred Petersen is a Senior Lecturer and Coordinator Scientific Photography, School of Media and Communication at RMIT University, a global university of technology and design.
This last photo is a confocal image of a marine organism (obelia hydroid) taken with the 10x objective. It was a winner from the 2016 International Images for Science competition.
Just one more – an honorable mention from 2017 Nikon Small World Competition.
The hydroid Ectopleura larynx is a fouling organism usually found attached to sunken ropes, floating buoys, piers, mussel shells, rocks, seaweed and the undersides of boats in the seas surrounding Great Britain and the Americas. This organism grows in colonies that can tolerate exposed habitats and strong water currents. Sometimes called Common Flowerheads in the fish farming industry this hydroid can cause problems by reducing water flow and quality.
Ectopleura larynx has two distinct rings of tentacles, one around its mouth and the other at the base of the head. In between these two rings, are the gonophores, or the sexual buds.
The hydroid Tubularia indivisa is also called oaten pipes. This large hydroid is also native to northeastern Atlantic Ocean, the North Sea, Norwegian Sea and the English Channel.
The solitary polps of Hydroid Tubularia indivisa are found on dull yellow unbranched stems that reach a height of 4-6”. The pinkish to red polps resemble flowers, having two concentric rings of tentacles, with the outer rings being paler and longer than the inner ring.
Hydroid Tubularia indivisa are preyed upon by nudibranch, another marine animal that looks like a snail without a shell.
These flower like hydroids are often considered delicate and soft. But beware. Their delicate looks belie their potent nature. They possess an armament of stinging cells equipped in their tentacles to capture and subdue prey. | <urn:uuid:cc6da698-ae7b-474a-9d96-a55104b7d22e> | 3 | 2,015 | Personal Blog | Science & Tech. | 47.638684 | 95,558,076 |
4 Fossil RecordWhat is a fossil? -The preserved remains of a once-living organism.How do fossils help scientists?1. Tells us what organisms lived long ago2. Shows how the Earth’s surface has changed.3. Help us understand what past environments may have been like.
5 How do we get fossils? Fossils are formed in SEDIMENTARY ROCK. If an organism dies and is buried by sediment rock, it’s bones are protected from rotting.Over time, more sediment layers build on top of the remains. Minerals replace all or part of the organism’s body. The preserved remains may later become exposed by erosion or the Earth’s movement.
6 How do we know the age of fossils? You have to DATE them!
7 Which fossil came first? Relative DatingAge of fossils RELATIVE toother rocks or fossils.2. Radioactive datingACTUAL age of fossils using the half life of radioactive isotopes
8 How does Relative Dating work? Rock layers form in order of age – the oldest layers on the bottom and the youngest on the top.Scientists use index fossils to compare the ages of fossils.Index fossil: a species easily recognizable, existed for a short period of time, and wide geographic range.*** Does NOT give age in years***ABCDE
9 How does Relative Dating work? Looking at this mountain, where would you expect to find the oldest fossils?BCDE
10 Which is older B or D?Index FossilsFound FossilsSAME AGE
11 How Does Radioactive Dating Work? Throughout an organism’s life, it takes in Carbon-14. Once the organism dies it no longer takes in Carbon-14. The C-14 present in the plant or animal begins to decay at a certain rate called half-life. Half-life: the length of time required for half the radioactive atoms in an organism to decay.Carbon-14 half life: 5,730 years
12 What do you notice about the percent of original C-14 remaining? Decay of Carbon-14Years from Present5,73011,46017,19022,92028,65034,38040,11045,84051,570Percent of Original C14 Remaining1005025220.127.116.11.560.780.390.20What do you notice about the percent of original C-14 remaining?
13 What are the scientific explanations for data showing periods of stasis and sudden appearance in the fossil record?The fossil record suggests that evolution has proceeded at different rates for different organisms at different times.
14 GradualismThe idea that evolution involves a slow, steady change in a particular line of descent.
15 Showing very little change over time Example: Horseshoe crabs STASISShowing very little change over time Example: Horseshoe crabs
16 Punctuated equilibrium Definition-Stable periods interrupted by rapid changesRapid Evolution may occur because:A) small pop becomes isolated from the large populationB)small group migrates to a new environment--FINCHES
18 Geographical Distribution Similar animals living in different locations are the product of different lines of evolutionary descent.
19 3rd type of Evidence Homologies 3 types of HomologiesAnatomicalMolecularDevelopmental (embryology)
20 Homologous Structures Homologous Structure: structures that have different mature forms but develop from the same embryonic tissues.Homologous structures provide strong evidence that all four-limbed vertebrates have descended, with modifications, from common ancestors.
21 Homologous Structures Not all homologous structures serve important functions. Vestigial organs: Organs in animals that are reduced in size to where they are just traces of homologous organs in other species.
22 Which structures are analogous? Homologous? Analogous StructuresAnalogous Structure: the similarity of structure between two species that are not closely related.Which structures are analogous? Homologous?Answer:Analogous- Bird to Insect, Bat to InsectHomologous- bird and bat wings
23 How do Analogous Structures Occur? Convergent Evolution: Species from different evolutionary branches may come to resemble one another if they live in very similar environments. Natural Selection may result in body structures and even whole organisms that look very similar without having the same common ancestor.
24 EmbryologyPigCowRabbitHumanComparative Embryology: the comparison of early stages of development Pharyngeal (throat) pouches in embryotic stages shows one sign that vertebrates evolved from a common ancestor.
25 Molecular BiologyMolecular Biology studies amino acid sequences of similar proteins in different species to discover the molecular history of evolution and common ancestor.
26 Molecular BiologyMolecular Biology is the BEST WAY to determine how closely species are related to one another.Which two species are most closely related based on these nucleotide sequences?Species 1ATGTAGCTGSpecies 2ATCTGACTCSpecies 3AGGTACCAGSpecies 4AGGCGGCAG | <urn:uuid:fb968568-76ca-421c-8659-c61d3a84ae18> | 3.734375 | 1,051 | Content Listing | Science & Tech. | 35.863244 | 95,558,077 |
3d vector component
The vector u = (3.9, u3) and the length of the vector u is 12. What is is u3?
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Determine length of the cube diagonal with edge 33 km.
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The prism with the edges of the lengths x cm, 2x cm and 3x cm has volume 20250 cm3. What is the area of surface of the prism?
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- Event probability
The probability of event P in 8 independent experiments is 0.33. What is the probability that the event P occurs in one experiment (probability is same)?
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For the various digits A, B, C is true: the square root of the BC is equal to the A and sum B+C is equal to A. Calculate A + 2B + 3C. (BC is a two-digit number, not a product).
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Calculate the square root of these numbers: | <urn:uuid:29aabbe6-53f2-40e8-b2c0-9c62252cf378> | 3.59375 | 609 | Tutorial | Science & Tech. | 85.626154 | 95,558,081 |
Radioactive dating lab Local adult lines
Radioactive dating requires the use of a decay curve.
Introduction: Scientists use radioactive dating to determine the time in years ago that an event happened.
Fossil carbonates of biological origin like foraminiferas, bivalves, corals and ostracodes are investigated to reconstruct past climate, circulation in the ocean or the history of lakes.
This activity was selected for the On the Cutting Edge Exemplary Teaching Collection Resources in this top level collection a) must have scored Exemplary or Very Good in all five review categories, and must also rate as “Exemplary” in at least three of the five categories.
If you place 100 pennies in a cup, shake them up, and pour the pennies out of the cup, how many do you predict will come up heads?
What are the chances of each penny coming up heads?
Plants and animals assimilate carbon 14 from carbon dioxide throughout their lifetimes.
If you flip a penny, what are the two ways the penny can land?
The Leibniz Laboratory for Radiometric Dating and Stable Isotope Research was established at the Christian-Albrechts-University of Kiel, Germany, in 1994.
It combined a new 3 MV Tandetron accelerator mass spectrometer (AMS) system with the conventional Radiocarbon and Mass-Spectormetry Laboratories, started in 1962.
Standard 3240-05 Students will investigate changes in Earth's crust and climate. The process of obtaining radioactive dates from samples is also shown.
Objective 3240-0501 Model Changes in the earth's surface. Observations: What are the two sides of a penny called? | <urn:uuid:51c9c3a2-ec85-44ae-ac87-12628451d33e> | 3.796875 | 358 | Content Listing | Science & Tech. | 35.267969 | 95,558,105 |
UK Drought & Water Scarcity
About Drought – The UK Drought & Water Scarcity Programme
The IEA is part of this vital and wide-ranging programme releasing a large number of datasets to support the important decisions being made about water scarcity, drought and low water flows.
This £12m programme is already supporting improved decision-making by taking an interdisciplinary approach and providing research that identifies, predicts and responds to the inter-relationships between their multiple drivers and impacts through four projects:
DRY: Drought risk and you, bringing together stories and science for better decision-making. www.dryproject.co.uk
Historic Droughts: Understanding past drought episodes to develop improved tools for the future. www.historicdroughts.ceh.ac.uk
IMPETUS: Improving predictions of drought to inform user decisions.
MaRIUS: Managing the risks, impacts and uncertainties of drought and water scarcity. www.mariusdroughtproject.org
Interdisciplinary & cross-sectoral
The IEA is heavily involved in About Drought – the knowledge-sharing project (also known as ENDOWS) which brings all the projects, data releases and outcomes together in one place and disseminates them to energy and water companies, industry, farmers, environmental organisations, communities, specialist groups such as wildlife conservation, and policy-makers. About Drought has brought together a range of expertise leading to significant advances in our understanding of the many complex, interlinked drivers of drought; the wide range of impacts; and the diversity of management responses.
Stakeholder events & workshops
Events including workshops, webinars and a cross-sectoral stakeholder conference bring together researchers and an academic conference is planned.
The programme has examined the range of ways in which drought and water scarcity affect people and the environment. These include physically-based global circulation models examining climate change through to the effect on crop yields, river habitats, power generation, oral histories and community modelling. These are just some of the subjects covered, for more visit www.aboutdrought.info
The programme is funded by the Natural Environment Research Council (NERC) in collaboration with the Economic and Social Research Council (ESRC), the Engineering and Physical Sciences Research Council (EPSRC), the Biotechnology and Biological Sciences Research Council (BBSRC) and the Arts and Humanities Research Council (AHRC) and contributes to NERC’s natural hazards and climate system strategic science themes.
Read more at www.aboutdrought.info
Watch the About Drought short documentary here.
For media enquiries please call Sally Stevens on 07740 674074.
Email the project office at info@AboutDrought.info | <urn:uuid:6f215ca7-d987-447a-a8a8-4cd3b51668a1> | 2.75 | 561 | About (Org.) | Science & Tech. | 27.774656 | 95,558,115 |
A wide-angle CCD camera based bistatic lidar (CLidar) is used to monitor aerosol profiles in the atmosphere of The Bahamas. A 2-Watt CW laser beam ranging from ground to zenith is captured in a single image by a camera fitted with a fisheye lens which is placed at a different location from the laser. Scattering altitude is determined simply from the geometry of the CLidar in contrast to monostatic lidar which requires expensive electronics to measure the time of flight of the returned signal. Each image contains both molecular and aerosol single angle scattering. A cloud free image is used to normalize the signal intensity to a model of molecular scattering at a region free of aerosol layer. Then molecular portion is subtracted to retrieve aerosol side scattering. An aerosol phase function was assumed to convert side scatter to aerosol extinction. Corrections due to transmission effects are then iteratively calculated until convergence is reached. Aerosol extinction drops off sharply above 1 km indicating the planetary boundary level which agrees well with the relative humidity measurements obtained from the radiosonde data of Nassau airport observation. Additionally, aerosols originated from the smoke of a charcoal grill operating near experimental site were efficiently detected near ground levels. Aerosol extinction at 20 m above sea level is 0.085 km-1 during grilling compared to 0.03 km-1 during no grilling. Excellent altitude resolution of the CLidar at the ground levels allows its use for in-situ environmental characterization without the overlap effects faced when using traditional lidar.
Amin S. Kabir, N. C. Sharma, John E. Barnes, Jalal Butt, and Mauricio Bridgewater, "Using a bistatic camera lidar to profile aerosols influenced by a local source of pollution," Proc. SPIE 10636, Laser Radar Technology and Applications XXIII, 106360L (Presented at SPIE Defense + Security: April 18, 2018; Published: 10 May 2018); https://doi.org/10.1117/12.2303544.
Conference Presentations are recordings of oral presentations given at SPIE conferences and published as part of the conference proceedings. They include the speaker's narration along with a video recording of the presentation slides and animations. Many conference presentations also include full-text papers. Search and browse our growing collection of more than 12,000 conference presentations, including many plenary and keynote presentations. | <urn:uuid:f7c14aaa-10a0-488f-9a94-ab8fa3d9574b> | 2.90625 | 501 | Academic Writing | Science & Tech. | 32.153571 | 95,558,132 |
SEPTEMBER 1, 2016 SOLAR ECLIPSE IN NIGERIA AND
As many parts of Nigeria, Africa and parts of the world experience Solar Eclipse, i decided to gather some important information you could need at least as a reminder a day before. Although Lagos is mentioned in the report below, it will cover large sections of Nigeria from North to South.
ANNULAR/PARTIAL SOLAR ECLIPSE – WHAT IT IS?
An annular solar eclipse will occur on September 1, 2016. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon’s apparent diameter is smaller than the Sun’s, blocking most of the Sun’s light and causing the Sun to look like anannulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.
1 September 2016 — Annular Solar Eclipse
The annular solar eclipse will be visible from Madagascar and locations in Central Africa. The Moon’s shadow will also cross parts of the Atlantic and Indian Oceans.
For most viewers in Africa, the eclipse will be a partial solar eclipse.
The eclipse will begin at 06:13 UTC on September 1, 2016. The maximum point will take place at 09:01 UTC, and the annularity will last for 3 minutes and 6 seconds.
Where to See the Eclipse
Regions seeing, at least, a partial eclipse: South in Asia, West in Australia, Much of Africa, Atlantic, Indian Ocean, Antarctica.
cities where annular eclipse is visible
Saint-Paul, Réunion (French)
Saint-Pierre, Réunion (French)
cities where partial eclipse is visible
São Tomé, Sao Tome and Principe
Malabo, Equatorial Guinea
Kinshasa, Congo Dem. Rep.
Dar es Salaam, Tanzania
Saint-Denis, Réunion (French)
Port Louis, Mauritius
Note: Percentage values (%) relate to moon coverage of the Sun and depends on location. Visibility is weather permitting.
Is this eclipse visible in Lagos?
The annular phase of this solar eclipse is not visible in Lagos, but it can be observed there as a partial solar eclipse
When the Eclipse Happens Worldwide
The eclipse starts at one location and ends at another. The times below are actual times (in UTC) when the eclipse occurs.
|Event||UTC Time||Time in Lagos*|
|First location to see the partial eclipse begin||1 Sep, 06:13||1 Sep, 07:13|
|First location to see the full eclipse begin||1 Sep, 07:17||1 Sep, 08:17|
|Maximum eclipse||1 Sep, 09:01||1 Sep, 10:01|
|Last location to see the full eclipse end||1 Sep, 10:55||1 Sep, 11:55|
|Last location to see the partial eclipse end||1 Sep, 12:00||1 Sep, 13:00|
* Local times shown do not refer to when the eclipse can be observed from Lagos. Instead, they indicate the times when the eclipse begins, is at its maximum, and ends, somewhere else on Earth. The corresponding local times are useful if you want to view the eclipse via a live webcam.
The Sun can be viewed safely with the naked eye only during the few brief seconds or minutes of a total solar eclipse. Partial eclipses, annular eclipses, and the partial phases of total eclipses are never safe to watch without taking special precautions. Even when 99% of the Sun’s surface is obscured during the partial phases of a total eclipse, the remaining photospheric crescent is intensely bright and cannot be viewed safely without eye protection [Chou, 1981; Marsh, 1982]. Do not attempt to observe the partial or annular phases of any eclipse with the naked eye. Failure to use appropriate filtration may result in permanent eye damage or blindness! | <urn:uuid:19c5a632-bded-40ba-8dbc-a50a665c5ebc> | 2.859375 | 857 | Knowledge Article | Science & Tech. | 49.364263 | 95,558,149 |
Electron spin resonance dating
Electron Spin Resonance Dating, or ESR dating, is a technique used to date newly formed materials, which Radiocarbon dating cannot, like carbonates, tooth enamel, or materials that have been previously heated like igneous rock. Electron spin resonance dating was first introduced to the science community in 1975, when Motoji Ikeya dated a speleothem in Akiyoshi Cave, Japan. ESR dating measures the amount of unpaired electrons in crystalline structures that were previously exposed to natural radiation. The age of substance can be determined by measuring the dosage of radiation since the time of its formation.
Electron Spin Resonance Dating is being used in fields like radiation chemistry, biochemistry, and as well as geology, archaeology, and anthropology. ESR dating is used instead of Radiocarbon dating because ESR dating can date newly formed materials or previously heated rock. The dating of buried teeth has served as the basis for the dating of human remains. Studies have been used to date burnt flint and quartz found in certain ancient ceramics. Newer ESR dating applications include dating previous earthquakes from fault gouge, past volcanic eruptions, and tectonic activity along coastlines.
Electron spin resonance dating can be described as trapped charge dating. Radioactivity causes negatively charged electrons to move from a ground state, the valence band, to a higher energy level at the conduction band. After a short time, electrons eventually recombine with the positively charged holes left in the valence band. The trapped electrons form para-magnetic centers and give rise to certain signals that can be detected under an ESR spectrometry. The amount of trapped electrons corresponds to the magnitude of the ESR signal. This ESR signal is directly proportional to the number of trapped electrons in the mineral, the dosage of radioactive substances, and the age.
Calculating the ESR Age
The electron spin resonance age of a substance is found from the following equation:
where DE is the equivalent dose, or paleodose (in Gray or Gy), i.e. the amount of radiation a sample has received during the time elapsed between the zeroing of the ESR clock (t = 0) and the sampling (t = T). D(t) is the dose rate (usually in Gy/ka or microGy/a), which is the average dose absorbed by the sample in 1 year. If D(t) is considered constant over time, then, the equation may be expressed as follows:
In this scenario, T is the age of the sample, i.e. the time during which the sample has been exposed to natural radioactivity since the ESR signal has been last reset. This happens by releasing the trapped charge, i.e. usually by either dissolution/recrystallization, heat, optical bleaching, or mechanical stress.
Determining the Accumulated Dose
The accumulated dose is found by the additive dose method and by an electron spin resonance (ESR) spectrometry. This when a sample is put into an external magnetic field and irradiated with certain dosages of microwaves that changes the energy level of the magnetic centers (changes the spin rotation) either to the same or opposite of the surrounding magnetic field. The change in magnetic properties only happens at specific energy levels and for certain microwave frequencies, there are specific magnetic strengths that cause these changes to occur (resonance). Positioning an ESR line in a spectrum corresponds to the proportion (g-value) of the microwave frequency to magnetic field strength used in the spectrometry. As the extrapolation toward zero of the ESR intensity occurs, the accumulated dose can then be determined.
Determining the Dose Rate
The dose rate is found from the summation of the concentrations of radioactive materials in the sample (internal dose rate) and its surrounding environment (external dose rate). The dosages of internal and external radioactivity must be calculated separately because of the varying differences between the two.
Factors to include in calculating the radioactivity:
- Uranium, Thorium and Potassium concentration
- Energies for alpha, beta and gamma rays of Uranium-238 and Thorium-232
- Correction factors related to the water content, the geometry of the sample, its thickness and density
- Cosmic ray dose rates – dependent on geographical position and thickness of covering sediments (300 pGy/a at sea level)
Trapped electrons only have a limited time frame when they are within the intermediate energy level stages. After a certain time range, or temperature fluctuations, trapped electrons will return to their energy states and recombine with holes. The recombination of electrons with their holes is only negligible if the average life is ten times higher than the age of the sample being dated.
- Grun, Rainer (1991). "ELECTRON SPIN RESONANCE DATING AND THE EVOLUTION OF MODERN HUMANS" (PDF). in-africa.org. Retrieved 2015-10-20.
- "Electron spin resonance dating of the Pleistocene coral reef tracts of Barbados". Quaternary Research. 29: 197–215. Bibcode:1988QuRes..29..197R. doi:10.1016/0033-5894(88)90030-0. Retrieved 2015-10-20.
- Ikeya, M. (1993-01-01). New Applications of Electron Spin Resonance: Dating, Dosimetry and Microscopy. World Scientific. ISBN 9789810212001.
- Rink, W. J (1997-12-05). "Electron spin resonance (ESR) dating and ESR applications in quaternary science and archaeometry". Radiation Measurements. 27 (5–6): 975–1025. Bibcode:1997RadM...27..975R. doi:10.1016/S1350-4487(97)00219-9.
- Grün, Rainer (1997-01-01). Taylor, R. E.; Aitken, Martin J., eds. Electron Spin Resonance Dating. Advances in Archaeological and Museum Science. Springer US. pp. 217–260. doi:10.1007/978-1-4757-9694-0_8#page-1. ISBN 978-1-4757-9696-4.
- Ikeya, Motoji (1993). New Applications of Electron Spin Resonance. World Scientific. ISBN 978-981-4317-21-4. | <urn:uuid:e44aeeab-f98f-4dcf-bf14-7322ef13b6cd> | 3.984375 | 1,368 | Knowledge Article | Science & Tech. | 46.896759 | 95,558,155 |
*Listen* to some of America's most pristine and polluted airways.
In the flat lands of California's Central Valley, oil pumps obscured by waving lines of fuel-richened air dip and rise on the horizon. Two hundred miles to the north and west, aging eighteen-wheelers pound through an urban bypass tunnel, staining the walls black with diesel fumes. Farther to the north, High Sierra pines scent the mountain air with notes of cinnamon and nutmeg, sending blue wisps of haze trailing gently upward.
Air is not the same everywhere. Across the extremes of the human environment, in both urban areas and wild, powerful natural and human forces combine to create intricate mixtures of chemicals that compose the air we breathe, seek for pleasure, or avoid. And now that air is made audible.
We created sounds from air samples (atmospheric particulate matter collected on filters) by first using gas chromatography to separate the thousands of compounds in the air (try it with markers at home) and then using mass spectrometry, which gives us a unique "spectrum" for chemicals based on their structure, to identify the compounds and assign them tones. Some compounds end up sounding clear and distinct, while others blur together into unresolvable chords. The result is a qualitative, sensory experience of hard, digital data. You can actually hear the difference between the toxic air of a truck tunnel (clogged with diesel hydrocarbons and carcinogenic particulate matter) and the fragrant air of the High Sierras.
In the following soundscapes you can listen to the air quality at study sites established across California by air pollution scientists at the University of California-Berkley's Department of Environmental Science, Policy, and Management, where new efforts are underway to better understand the air we breathe and to devise new efforts to improve our polluted areas.
Take a listen.
The Caldecott Tunnel, Oakland, CA
The Caldecott Tunnel cuts east from Oakland through the Berkley Hills, linking greater Contra Costa County with the Bay area. To capture the direct emissions of cars and trucks (which often vary greatly from projected emissions) we dangled an air sampler from a ventilation passageway above the busy road. What you hear in the soundscape is an eerie mixture of highly unsaturated compounds called "polycyclic aromatic hydrocarbons" (those distinct chirps at the beginning) and complex, saturated heavy hydrocarbons (the long, low droning chords at the end). Both of these result from burning fossil fuels. And many are dangerous carcinogens, mutagens, and teratogens -- linked to cancers, gene mutations, and birth and developmental defects.
The town of Bakersfield sits in the middle of California's Central Valley on swampland reclaimed from the nearby Kern River. It hosts, supposedly, the world's largest ice cream plant (Dreyer's Grand!) and sits in one of our country's most productive oil counties (Kern County). It is also, according to the American Lung Association, America's most air-polluted city. You'll notice it sounds a lot like a contained highway tunnel -- the result of fresh hydrocarbons from a main trucking highway and oil and gas fields surrounding the sampling site.
Several years ago almost 100 air and climate scientists joined forces to resolve a lingering question in atmospheric science: Why do existing air quality models under-predict urban particulate (unhealthy airborne particle) concentrations by a factor of between two and 10? Their efforts met on the campus of Caltech in Pasadena, which sits just downwind of greater Los Angeles.
Because it is so close to LA and major shipping ports, you would expect Pasadena to sound the same as Bakersfield, or perhaps the Oakland tunnels. But in Southern California winds blow in from the ocean and trap the smog of LA at the foot of the surrounding San Gabriel Mountains before carrying it down to Pasadena. The usual hydrocarbon slurry then has a chance to "cook" in the oxidizing atmosphere of the hot mountain foothills. The resulting soundscape is more bubbly than the pure hydrocarbon samples above, as you can hear the new presence of complex oxygenated compounds.
The High Sierras
In a remote pine forest deep in the Sierra Mountains we gathered particulate data from the top of a swaying tower, which was installed to take measurements from above and inside the tree canopy. This soundscape starts with bubbly, diverse tones -- the result of small compounds (smaller compounds show up earlier in the data and hence earlier in the soundscape) that plants release to attract or repel insects. When you smell the sharp tang of pine pitch or fragrance of mountain laurel, you are smelling the volatile chemicals produced by the plant, which have evaporated and taken to the air, where hungry herbivores and pollinators can detect them.
Despite the remoteness of the study site, you can hear the influence of vehicle emissions later in the soundscape, as low, Bakersfield-type drones fill in. Though this site is far from any major cities or highways, winds bring emissions up from Sacramento during the day and back down the mountain at night -- a common pattern in the Central Valley of California -- making the influence of humanity nearly impossible to escape.
The negative influence of human emissions on forests and remote areas is a problem that is increasing throughout the country and the world, and it is leading to one of the major issues currently being tackled in the scientific community. When human and natural emissions interact, as they do outside our cities, more particulate matter (smog and haze) is formed than we expect. This leads to inaccuracies in pollution models and, unsurprisingly, makes improving air quality more difficult. In some places, like the American Southeast, these poorly understood interactions have resulted in unpredicted, large-scale trends in regional warming and cooling.
These interactions are also, incidentally, one of the reasons President Reagan once said that trees pollute more than people do.
In short, to better understand and regulate our changing climate, the consequences of mixing those bubbly, natural tones with that droning, fossil-fuel chord need to be better studied.
Data analysis contributing to this project was performed by the research group of Dr. Goldstein at UC Berkeley. We'd like to thank the research groups of Dr. Harley (UC Berkeley) and Dr. Surratt (UNC Chapel Hill) for collecting samples.
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Scientists have known for decades that Greenland’s ice sheet is melting, but they may have underestimated just how much water the second-largest ice sheet on the planet is shedding. New research indicates that a key section of northeast Greenland thought to be stable is actually dumping billions of tons of water into the ocean annually after a barrier of ice debris that had blocked its flow finally gave way.
"We're seeing an acceleration of ice loss," Michael Bevis, professor of earth sciences at Ohio State University and co-author of a new study on Greenland’s melting ice sheet, told USA Today. "Now, there's more ice leaving than snow arriving."
The study, published in the journal Nature Climate Change, included the work of an international team of researchers from Denmark, the Netherlands, the U.S. and China. According to AFP, the team measured the thickness of Greenland’s ice using four satellites and a network of 50 GPS sensors along the island’s coast. The monitors calculate the size of the Greenland ice sheet using Earth’s natural elasticity. When ice melts, it relieves pressure on the land underneath it, causing the ground to rebound just slightly. The monitors can sense these small changes.
The data showed that between 2003 and 2012, the northeast region of Greenland’s ice sheet retreated 12.4 miles following a three-year stretch of particularly high temperatures. The melting ice dumped 10 billion tons of water into the ocean every year during that time. According to researchers, the island is estimated to contribute .5mm to 3.2mm (.012 inches to .13 inches) to the annual rise in global sea levels.
“These new measurements show that the sleeping giant is awakening and suggest -- given likely continued Arctic warming -- that it’s not going back to bed,” Jason Box, a glaciologist at the Geological Survey of Denmark and Greenland, told Climate Central.
The ice melt in the northeast region of Greenland is particularly troubling because the ice stream there, known as Zachariae, stretches more than 370 miles into the island’s center where it joins the heart of Greenland’s ice reservoir. This “river” carries melting ice water from Greenland’s interior to the oceans.
"The Greenland ice sheet has contributed more than any other ice mass to sea-level rise over the last two decades and has the potential, if it were completely melted to raise global sea level by more than seven meters,” Jonathan Bamber, a professor at Britain's University of Bristol, told AFP.
Greenland is the world’s largest island holds roughly 680,000 cubic miles of ice within its ice sheet. The ice is up to 3 miles thick in some areas and covers about three-fourths of the island.
Between 1990 and 2011, climate change caused ocean surface temperatures around Greenland to rise 1.8 to 3.6 degrees Fahrenheit. Researchers say that water from Greenland’s melting ice accounts for nearly one-sixth of annual sea-level rise. | <urn:uuid:07ba20c4-1b79-48cf-8264-1fe8aab92076> | 3.875 | 656 | News Article | Science & Tech. | 55.170394 | 95,558,179 |
Scientists looking to create a potent blend of enzymes to transform materials like corn stalks and wood chips into fuels have developed a test that should turbocharge their efforts.
This is the fungus T. reesei.
Credit: Courtesy of PNNL
The new research, published in October in the journal Molecular BioSystems, is part of a worldwide effort to create fuels from plants that are plentiful and aren't part of the food supply. It's possible to do this today, but the process is costly, laborious and lengthy.
The findings by chemists and colleagues at the Department of Energy's Pacific Northwest National Laboratory open the possibility that laboratory research that now takes months could be reduced to days, and that scientists will be able to assess more options for biofuel development than is possible today.
Many of today's efforts revolve around the fungus Trichoderma reesei, which introduced itself to U.S. troops during World War II by chewing through their tents in the Pacific theater. Seventy years later, T. reesei is a star in the world of biofuels because of its ability to churn out enzymes that chew through molecules like complex sugars.
The breakdown of large sugar polymers into smaller compounds that can then be further converted to fuel compounds is the final, crucial step in the effort to make fuels from materials like switchgrass and corn stalks. These plants and many others are full of energy, stored in carbon bonds, which can be converted into fuel, if scientists can find ways to free the compounds that store the energy from the tough structural material, known as lignocellulose, which holds the plants together.
Lignocellulose is what stands between you and a tankful of fuel created from corn stalks or switchgrass.
"The ultimate goal is to begin with a plant material like corn stalks, for instance, and to subject it to a cocktail of enzymes that would convert those plants to fuel," said chemist Aaron Wright, who led the PNNL team. "It takes a series of steps to do that, and the cost has to come down if these fuels are to compete seriously with traditional hydrocarbon-based fuels."
T. reesei chews through materials naturally, cutting through the chemical "wrapping" much like a person with scissors cuts through a tightly wrapped ribbon around a gift, freeing the inner contents for enjoyment. The fungus actually makes dozens of cutting enzymes, each of which attacks the wrapping differently. Chemists like Wright are trying to combine and improve upon the best ones to create a potent chemical cocktail, a mix of enzymes that accomplishes the task super efficiently. That would bring down the cost of producing biofuels.
Wright's study focused on a subset of the fungus's collection of cutting tools, on enzymes known as glycoside hydrolases. It's their job to break down complex sugars into simple sugars, a key step in the fuel production process.
To assess the effectiveness of mixtures of these enzymes, scientists must either measure the overall performance of the mixture, or they must test the component enzymes one at a time to see how each reacts to different conditions like temperature, pressure and pH.
Wright's team developed a way to measure the activity of each of the ingredients simultaneously, as well as the mixture overall. Instead of needing to run a series of experiments, each focusing on a separate enzyme, the team runs one experiment and tracks precisely how each of dozens of enzymes reacts to changing conditions.
A series of experiments detailing the activity of 30 enzymes, for instance, now might be accomplished in a day or two with the new technology, compared to several months using today's commonplace methods, the scientists say.
The key to the work is a chemical probe the team created to monitor the activity of many enzymes at once. The heart of the system, known as activity-based protein profiling, is a chemical probe that binds to glycoside hydrolases and gives off information indicating just how active each of those enzymes is moment by moment.
"Identifying exactly which enzymes are doing most of the work you need done is crucial for making this an economical process," said Wright. "We're trying to keep tabs on the precise activity of every enzyme as each goes through a very complex process, as conditions like temperature and pH vary, to measure their activity through each stage."
"We can test the whole mixture, and we can also tease out each individual contribution. People have not been able to do that all at once before," added Wright, whose study was funded by PNNL.
Many of the measurements for the study, such as the measures of protein activity using mass spectrometry, were done at EMSL, the DOE's Environmental Molecular Sciences Laboratory on the PNNL campus. Wright's team included Lindsey Anderson, David Culley, Beth Hofstad, Lacie Chauvigné-Hines, Erika Zink, Samuel Purvine, Richard Smith, Stephen Callister, and Jon Magnuson, all of PNNL.
Reference: Lindsey N. Anderson, David E. Culley, Beth A. Hofstad, Lacie M. Chauvigné-Hines, Erika M. Zink, Samuel O. Purvine, Richard D. Smith, Stephen J. Callister, Jon M. Magnuson and Aaron T. Wright, Activity-based protein profiling of secreted cellulolytic enzyme activity dynamics in Trichoderma reesei QM6a, NG14, and RUT-C30, Molecular BioSystems, Oct. 9, 2013, DOI: 10.1039/c3mb70333a.
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The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
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Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
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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Doppler effect The Doppler effect, named after Christian Doppler, is the change in frequency and wavelength of a wave as perceived by an observer moving relative to the source of the waves. For waves that propagate in a wave medium, such as sound waves, the velocity of the observer and of the source are relative to the medium in which the waves are transmitted.
The total Doppler effect may therefore result from motion of the source, motion of the observer, or motion of the medium. Each of these effects is analysed separately. For waves which do not require a medium, such as light or gravity in special relativity, only the relative difference in velocity between the observer and the source needs to be considered. [pic] [pic] A source of waves moving to the left. The frequency is higher on the left, and lower on the right. | |
Doppler first proposed the effect in 1842 in the monograph Uber das farbige Licht der Doppelsterne und einige andere Gestirne des Himmels – Versuch einer das Bradleysche Theorem als integrierenden Teil in sich schliessender allgemeiner Theorie (On the coloured light of the binary refracted stars and other celestial bodies – Attempt of a more general theory including Bradley’s theorem as an integral part). The hypothesis was tested for sound waves by the Dutch scientist Christoph Hendrik Diederik Buys Ballot in 1845.
He confirmed that the sound’s pitch was higher as the sound source approached him, and lower as the sound source receded from him. Hippolyte Fizeau discovered independently the same phenomenon on electromagnetic waves in 1848 (in France, the effect is sometimes called “effet Doppler-Fizeau”). It is often overlooked that in Doppler’s publications (and also Einstein’s in his discussion of the Doppler effect) he explicitly acknowledges that his formulae are only approximate since he made several mathematical approximations in his derivation.
Doppler’s derivation is repeated more or less verbatim in most modern textbooks but often without the warning that the formulas are only valid in some (experimentally often seen) limits. In Britain, John Scott Russell made an experimental study of the Doppler effect. In 1848, Russell reported his study of the Doppler effect. (J. S. Russell, “On certain effects produced on sound by the rapid motion of the observer”, Brit. Assn. Rep. , vol. 18, p. 37 (1848). An English translation of Doppler’s 1842 monograph can be found in the book by Alec Eden, “The search for Christian Doppler”, Springer-Verlag 1992. In this book, Eden felt doubtful regarding Doppler’s conclusions on the colour of double stars, but he was convinced regarding Doppler’s conclusions on sound. [pic] [pic] An illustration of the Doppler effect. The relationship between observed frequency f’ and emitted frequency f is given by: [pic] where pic]is the velocity of waves in the medium (in air at T degrees Celsius, this is 332(1 + T/273)1/2 m/s) [pic]is the velocity of the source (the object emitting the sound) Because we are using an inertial reference system, the velocity of an object moving towards the observer is considered as negative, so the detected frequency increases (This is because the source’s velocity is in the denominator. ) Conversely, detected frequency decreases when the source moves away, and so the source’s velocity is added when the motion is away.
In the limit where the speed of the wave is much greater than the relative speed of the source and observer (this is often the case with electromagnetic waves, e. g. light), the relationship between observed frequency f? and emitted frequency f is given by: |Change in frequency |Observed frequency | |[pic] |[pic] | where [pic]is the transmitted frequency [pic]is
If either of these two approximations are violated, the formulae are no longer accurate. Analysis It is important to realize that the frequency of the sounds that the source emits does not actually change. To understand what happens, consider the following analogy. Someone throws one ball every second in a man’s direction. Assume that balls travel with constant velocity. If the thrower is stationary, the man will receive one ball every second. However, if the thrower is moving towards the man, he will receive balls more frequently because the balls will be less spaced out.
The converse is true if the thrower is moving away from the man. So it is actually the wavelength which is affected; as a consequence, the perceived frequency is also affected. It may also be said that the velocity of the wave remains constant whereas wavelength changes; hence frequency also changes. If the moving source is emitting waves through a medium with an actual frequency f0, then an observer stationary relative to the medium detects waves with a frequency f given by [pic]which can be written as: [pic], here v is the speed of the waves in the medium and vs, r is the speed of the source with respect to the medium (positive if moving away from the observer, negative if moving towards the observer), radial to the observer. With a relatively slow moving source, vs, r is small in comparison to v and the equation approximates to [pic]. A similar analysis for a moving observer and a stationary source yields the observed frequency (the observer’s velocity being represented as vo): [pic], where the same convention applies : vo is positive if the observer is moving way from the source, and negative if the observer is moving towards the source. These can be generalized into a single equation with both the source and receiver moving. However the limitations mentioned above still apply. When the more complicated exact equation is derived without using any approximations (just assuming that everything: source, receiver, and wave or signal are moving linearly) several interesting and perhaps surprising results are found. For example, as Lord Rayleigh noted in his classic book on sound, by properly moving it is possible to hear a symphony being played backwards.
This is the so-called “time reversal effect” of the Doppler effect. Other interesting cases are that the Doppler effect is time dependent in general (thus we need to know not only the source and receivers’ velocities, but also their positions at a given time) and also in some circumstances it is possible to receive two signals or waves from a source (or no signal at all). In addition there are more possibilities than just the receiver approaching the signal and the receiver receding from the signal. All these additional complications are for the classical—i. . , nonrelativistic Doppler effect. However, all these results also hold for the relativistic Doppler effect as well. The first attempt to extend Doppler’s analysis to light waves was soon made by Fizeau. In fact, light waves do not require a medium to propagate and the correct understanding of the Doppler effect for light requires the use of the Special Theory of Relativity. See relativistic Doppler effect. Applications [pic] [pic] A stationary microphone records moving police sirens at different pitches depending on their relative direction.
Everyday The siren on a passing emergency vehicle will start out higher than its stationary pitch, slide down as it passes, and continue lower than its stationary pitch as it recedes from the observer. Astronomer John Dobson explained the effect thus: “The reason the siren slides is because it doesn’t hit you. ” In other words, if the siren approached the observer directly, the pitch would remain constant (as vs, r is only the radial component) until the vehicle hit him, and then immediately jump to a new lower pitch.
Because the vehicle passes by the observer, the radial velocity does not remain constant, but instead varies as a function of the angle between his line of sight and the siren’s velocity: [pic] where vs is the velocity of the object (source of waves) with respect to the medium, and ? is the angle between the object’s forward velocity and the line of sight from the object to the observer. Astronomy [pic] [pic] Redshift of spectral lines in the optical spectrum of a supercluster of distant galaxies (right), as compared to that of the Sun (left).
The Doppler effect for electromagnetic waves such as light is of great use in astronomy and results in either a so-called redshift or blueshift. It has been used to measure the speed at which stars and galaxies are approaching or receding from us, that is, the radial velocity. This is used to detect if an apparently single star is, in reality, a close binary and even to measure the rotational speed of stars and galaxies. The use of the Doppler effect for light in astronomy depends on our knowledge that the spectra of stars are not continuous.
They exhibit absorption lines at well defined frequencies that are correlated with the energies required to excite electrons in various elements from one level to another. The Doppler effect is recognizable in the fact that the absorption lines are not always at the frequencies that are obtained from the spectrum of a stationary light source. Since blue light has a higher frequency than red light, the spectral lines of an approaching astronomical light source exhibit a blueshift and those of a receding astronomical light source exhibit a redshift.
Among the nearby stars, the largest radial velocities with respect to the Sun are +308 km/s (BD-15°4041, also known as LHS 52, 81. 7 light-years away) and -260 km/s (Woolley 9722, also known as Wolf 1106 and LHS 64, 78. 2 light-years away). Positive radial velocity means the star is receding from the Sun, negative that it is approaching. Temperature measurement Another use of the Doppler effect, which is found mostly in astronomy, is the estimation of the temperature of a gas which is emitting a spectral line.
Due to the thermal motion of the gas, each emitter can be slightly red or blue shifted, and the net effect is a broadening of the line. This line shape is called a Doppler profile and the width of the line is proportional to the square root of the temperature of the gas, allowing the Doppler-broadened line to be used to measure the temperature of the emitting gas. Radar Main article: Doppler radar The Doppler effect is also used in some forms of radar to measure the velocity of detected objects.
A radar beam is fired at a moving target—a car, for example, as radar is often used by police to detect speeding motorists—as it approaches or recedes from the radar source. Each successive wave has to travel further to reach the car, before being reflected and re-detected near the source. As each wave has to move further, the gap between each wave increases, increasing the wavelength. In some situations, the radar beam is fired at the moving car as it approaches, in which case each successive wave travels a lesser distance, decreasing the wavelength.
In either situation, calculations from the Doppler effect accurately determine the car’s velocity. The proximity fuze which was developed during World War II also relies on Doppler radar. Medical imaging and blood flow measurement An echocardiogram can, within certain limits, produce accurate assessment of the direction of blood flow and the velocity of blood and cardiac tissue at any arbitrary point using the Doppler effect. One of the limitations is that the ultrasound beam should be as parallel to the blood flow as possible.
Velocity measurements allow assessment of cardiac valve areas and function, any abnormal communications between the left and right side of the heart, any leaking of blood through the valves (valvular regurgitation), and calculation of the cardiac output. Contrast-enhanced ultrasound using gas-filled microbubble contrast media can be used to improve velocity or other flow-related medical measurements. Although “Doppler” has become synonymous with “velocity measurement” in medical imaging, in many cases it is not the frequency shift (Doppler shift) of the received signal that is measured, but the phase shift (when the received signal arrives).
Velocity measurements of blood flow are also used in other fields of medical ultrasonography, such as obstetric ultrasonography and neurology. Velocity measurement of blood flow in arteries and veins based on Doppler effect is an effective tool for diagnosis of vascular problems like stenosis. Flow measurement Instruments such as the laser Doppler velocimeter (LDV), and Acoustic Doppler Velocimeter (ADV) have been developed to measure velocities in a fluid flow. The LDV and ADV emit a light or acoustic beam, and measure the Doppler shift in wavelengths of reflections from particles moving with the flow.
The actual flow is computed as a function of the water velocity and face. This technique allows non-intrusive flow measurements, at high precision and high frequency. Underwater acoustics In military applications the Doppler shift of a target is used to ascertain the speed of a submarine using both passive and active sonar systems. As a submarine passes by a passive sonobuoy, the stable frequencies undergo a Doppler shift, and the speed and range from the sonobuoy can be calculated. If the sonar system is mounted on a moving ship or an another submarine, then the relative velocity can be calculated. | <urn:uuid:b634137c-e6ba-4dc6-909f-3f7f7d8efc5e> | 4.1875 | 2,884 | Knowledge Article | Science & Tech. | 37.466845 | 95,558,197 |
Species Detail - Cercidospora epipolytropa - 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).
Didymella epipolytropa, Didymosphaeria epipolytropa, Thelidium epipolytropum, Verrucaria epipolytropa
24 May (recorded in 2013)
7 June (recorded in 2016)
National Biodiversity Data Centre, Ireland, Cercidospora epipolytropa, accessed 23 July 2018, <https://maps.biodiversityireland.ie/Species/157561> | <urn:uuid:66a721b4-c16e-4ddd-993a-2b141a1a524d> | 3.03125 | 176 | Structured Data | Science & Tech. | 1.128675 | 95,558,215 |
Physicists have developed a new protocol to detect entanglement of many-particle quantum states using a much easier approach. The protocol is particularly interesting for characterizing entanglement in systems involving many particles. These systems could help us not only to improve our understanding of matter but to develop measurement techniques beyond current existing technologies.
In quantum theory, interactions among particles create fascinating correlations known as entanglement that cannot be explained by any means known to the classical world. Entanglement is a consequence of the probabilistic rules of quantum mechanics and seems to permit a peculiar instantaneous connection between particles over long distances that defies the laws of our macroscopic world - a phenomenon that Einstein referred to as “spooky action at a distance.”
Developing protocols to detect and quantify entanglement of many-particle quantum states is a key challenge for current experiments because entanglement becomes very difficult to study when many particles are involved.
“We are able to control smaller particle ensembles well, where we can measure entanglement in a relatively straight forward way,” says quantum physicist Philipp Hauke. However, “when we are dealing with a large system of entangled particles, this measurement is extremely complex or rather impossible because the resources required scale exponentially with the system size.”
Philipp Hauke and Peter Zoller from the Department of Theoretical Physics at the University of Innsbruck and the Institute for Quantum Optics and Quantum Information (IQOQI) at the Austrian Academy of Sciences in collaboration with Markus Heyl from the Technical University of Munich, and Luca Tagliacozzo from ICFO - The Institute of Photonic Sciences have found a new way to detect certain properties of many-particle entanglement independent of the size of the system and by using standard measurement tools.
Entanglement measurable via susceptibility
“When dealing with more complex systems, scientists had to carry out a large number of measurements to detect and quantify entanglement between many particles,” says Philipp Hauke. “Our protocol avoids this problem and can also be used for determining entanglement in macroscopic objects, which was nearly impossible until now.”
With this new method theoretical physicists are able to use tools already well established experimentally. In their study, published in Nature Physics, the team of researchers give explicit examples to demonstrate their framework: The entanglement of many-particle systems trapped in optical lattices can be determined by laser spectroscopy, and the well-established technique of neutron scattering may be used for measuring it in solid-state systems.
As the physicists have been able to show, the quantum Fisher information, which represents a reliable witness for genuinely multipartite entanglement, is in fact measurable. The researchers have highlighted that entanglement can be detected by measuring the dynamic response of a system caused by a perturbation, which can be determined by comparing individual measurements. “For example, when we move a sample through a time-dependent magnetic field, we can determine the system’s susceptibility towards the magnetic field through the measurement data and thereby detect and quantify internal entanglement,” explains Hauke.
Quantum metrology, i.e. measurement techniques with increased precision exploiting quantum mechanics, is not the only important field of application of this protocol. It will also provide new perspectives for quantum simulations, where quantum entanglement is used as a resource for studying properties of quantum systems. In solid-state physics, the protocol may be used to investigate the role of entanglement in many-body systems, thereby providing a deeper understanding of quantum matter.
The research work was supported by the Austrian Science Fund and the European Research Council.
Publication: Measuring multipartite entanglement via dynamic susceptibilities. Philipp Hauke, Markus Heyl, Luca Tagliacozzo, Peter Zoller. Advanced Online Publication, Nature Physics, on 21 March 2016. http://dx.doi.org/10.1038/nphys3700
Department of Theoretical Physics
University of Innsbruck
phone: +43 512 507 4787
University of Innsbruck
phone: +43 512 507 32022
http://www.uibk.ac.at/th-physik/qo - Quantum Optics Theory Group, University of Innsbruck
Dr. Christian Flatz | Universität Innsbruck
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12.07.2018 | University of Rochester
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
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Calculation of primary nuclear interferences occurring in neutron activation analysis with a slowpoke reactor
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The cross-sections for (n, p) and (n, α) reactions which may interfere with (n, γ) reactions used in thermal neutron activation analysis have been calculated systematically using an empirical formula in conjunction with published σ-values. The interference factors (IF) have been subsequently calculated for flux conditions that prevail in a SLOWPOKE II reactor and both cross sections and interference factors have been listed in a tabulated form. The significance and usefulness of IF's thus obtained is discussed from the standpoint of trace analysis. For a number of low-Z matrices, their magnitude is such that the measurement of certain constituents at the ppm level by instrumental analysis is rendered virtually impossible, as for the following matrix—trace element pairs=Al/Mg, Na/Al, P/Si, S/P and Cl/S. For higher Z elements, interferences can be neglected in most instances.
KeywordsNeutron Activation Analysis Neutron Flux 86Sr Fast Neutron Effective Energy
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- 1.A. CALAMAND, Handbook on Nuclear Activation Cross Sections, IAEA, Vienna, 1974, p. 273.Google Scholar
- 2.D. J. HUGHES, Pile Neutron Research, Adison-Wesley Publ. Co. 1953, p. 93.Google Scholar
- 3.F. W. WALKER, G. J. KROUAC, F. M. ROURKE, Chart of the Nuclides, Knolls Atomic Power Lab., 1977.Google Scholar | <urn:uuid:a222739b-c687-4f76-9804-80587a2431de> | 2.625 | 355 | Truncated | Science & Tech. | 55.104356 | 95,558,244 |
lahyph – Hyphenation patterns for the Latin language
These are patterns for the Latin language mainly in modern spelling (u when u is needed and v when v is needed); medieval spelling with the ligatures \ae and \oe and the (uncial) lowercase ‘v’ written as a ‘u’ is also supported; apparently there is no conflict between the patterns of modern Latin and those of medieval Latin.
The patterns support the restricted character set of the OT1-encoding (obviously without the ligature characters), as well as T1-encoded usage.
|Licenses||The LaTeX Project Public License|
|Contained in||TeX Live as hyphen-latin|
Maybe you are interested in the following packages as well.
- glhyph: Hyphenation patterns for Galician
- eehyph: Hyphenation patterns for the Estonian language
- bghyphen: Hyphenation patterns for Bulgarian
- fahyph: Hyphenation patterns for Persian (in Unicode) | <urn:uuid:731f6b8b-d5a7-4602-b92a-6c33f358ceb1> | 2.578125 | 222 | Documentation | Software Dev. | 4.925199 | 95,558,256 |
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Hurricane Rita went down in the record books as the strongest hurricane ever in the Gulf of Mexico, beating a record that Katrina had set about three weeks earlier.
While churning in the Gulf, the maximum sustained winds of Rita reached 180 mph with the central pressure dropping as low as 895 mb (26.43 inches Hg). Only Hurricane Wilma in 2005, Hurricane Gilbert in 1988 and The Labor Day Hurricane in 1935 have been stronger hurricanes with lower pressures in the Atlantic Ocean.
Besides setting a record for being the strongest Gulf hurricane ever, this was the first time on record that two storms strengthened into Category 5 hurricanes in the Gulf of Mexico.
Rita crashed onshore along the Texas-Louisiana border as a Category 3 storm with maximum sustained winds of 120 mph on Sept. 24, 2005.
More than 3 million Texas and Louisiana residents were evacuated ahead of Rita, which caused severe flooding in coastal areas of Texas and Louisiana. NOAA reports that storm surge of 15 feet trapped residents who stayed behind in coastal Louisiana parishes of Cameron, Jefferson Davis, Terrebonne and Vermilion.
According to NOAA, more than a million people lost power due to Rita's lashing winds. Many were in the dark for several days and weeks. Meanwhile, dozens of tornadoes touched down across the Deep South from Sept. 24-25, while the storm plowed into the Gulf Coast.
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Showers and thunderstorms will congregate over the southeastern United States into the weekend, elevating the risk of flash flooding and outdoor disruptions.
Racers of the 2018 Tour de France will emerge from the mountains on Friday; however, new challenges await.
Prior to the arrival of much cooler and less humid air at midweek, thunderstorms packing torrential downpours and locally damaging winds will rattle the northeastern United States into Tuesday evening.
More than 1,450 emergency personnel are still working to contain the massive wildfire near California’s Yosemite National Park that took a deadly turn over the weekend.
Rounds of thunderstorms packing torrential rain and gusty winds will erupt along a temperature contrast zone across the Great Plains through the middle of this week.
A lightning strike can result in a cardiac arrest and death, and the most lightning strikes occur during warm summer months when people are outside enjoying the weather.
Saving the planet’s oceans from plastic pollution isn’t on the agenda of a typical sixth grader. However, Anna Du is working to achieve just that.
After passing over Hainan, Tropical Storm Son-tinh has its sights set on China and northern parts of Vietnam and Laos in the coming days. | <urn:uuid:4e23d0e5-f13d-448e-9a67-a87af65c5112> | 2.828125 | 581 | News Article | Science & Tech. | 48.28507 | 95,558,261 |
Which parts of these framework bridges are in tension and which parts are in compression?
Given the equation for the path followed by the back wheel of a bike, can you solve to find the equation followed by the front wheel?
See how enormously large quantities can cancel out to give a good approximation to the factorial function.
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Work with numbers big and small to estimate and calculate various quantities in biological contexts.
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There has been a murder on the Stevenson estate. Use your analytical chemistry skills to assess the crime scene and identify the cause of death... | <urn:uuid:20ea4b68-3f6c-47cd-9038-9ca06abde2d1> | 3.109375 | 1,009 | Content Listing | Science & Tech. | 50.601767 | 95,558,275 |
Research chemists at the University of Warwick have devised and patented a new process called Living and Controlled Radical Polymerisation which can cheaply and easily grow designer polymers (plastics). They have already used the process to produce a wide range of designer polymer designs that are now being tested by major companies for use in applications as diverse as hairspray, anti-obesity drugs and inkjet printer ink.
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The research team has just been granted a patent on the process in Europe and the US and Professor Haddleton has now formed a spin out company called "Warwick Effect Polymers Ltd" (WEP) which has already begun to produce to order designer polymers for high-value applications such as inkjet printer ink, hairspray and shampoo, adhesives, pharmaceuticals, biomaterials and medical devices for companies such as, Unilever, Proctor and Gamble, BP Avecia, and GelTex Inc. WEP is now seeking partners to exploit the technology in licensing and joint venture agreements.
Peter Dunn | alphagalileo
Scientists uncover the role of a protein in production & survival of myelin-forming cells
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
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A strangelet is a hypothetical particle consisting of a bound state of roughly equal numbers of up, down, and strange quarks. An equivalent description is that a strangelet is a small fragment of strange matter, small enough to be considered a particle. The size of an object composed of strange matter could, theoretically, range from a few femtometers across (with the mass of a light nucleus) to arbitrarily large. Once the size becomes macroscopic (on the order of metres across), such an object is usually called a strange star. The term "strangelet" originates with Edward Farhi and R. L. Jaffe. Strangelets have been suggested as a dark matter candidate.
- 1 Theoretical possibility
- 2 Natural or artificial occurrence
- 3 Dangers
- 4 Debate about the strange matter hypothesis
- 5 In fiction
- 6 See also
- 7 References
- 8 Further reading
Strange matter hypothesis
The known particles with strange quarks are unstable because the strange quark is heavier than the up and down quarks, so strange particles, such as the Lambda particle, which contains an up, down, and strange quark, always lose their strangeness, by decaying via the weak interaction to lighter particles containing only up and down quarks. But states with a larger number of quarks might not suffer from this instability. This is the "strange matter hypothesis" of Bodmer and Witten. According to this hypothesis, when a large enough number of quarks are collected together, the lowest energy state is one which has roughly equal numbers of up, down, and strange quarks, namely a strangelet. This stability would occur because of the Pauli exclusion principle; having three types of quarks, rather than two as in normal nuclear matter, allows more quarks to be placed in lower energy levels.
Relationship with nuclei
A nucleus is a collection of a large number of up and down quarks, confined into triplets (neutrons and protons). According to the strange matter hypothesis, strangelets are more stable than nuclei, so nuclei are expected to decay into strangelets. But this process may be extremely slow because there is a large energy barrier to overcome: as the weak interaction starts making a nucleus into a strangelet, the first few strange quarks form strange baryons, such as the Lambda, which are heavy. Only if many conversions occur almost simultaneously will the number of strange quarks reach the critical proportion required to achieve a lower energy state. This is very unlikely to happen, so even if the strange matter hypothesis were correct, nuclei would never be seen to decay to strangelets because their lifetime would be longer than the age of the universe.
The stability of strangelets depends on their size. This is because of (a) surface tension at the interface between quark matter and vacuum (which affects small strangelets more than big ones), and (b) screening of charges, which allows small strangelets to be charged, with a neutralizing cloud of electrons/positrons around them, but requires large strangelets, like any large piece of matter, to be electrically neutral in their interior. The charge screening distance tends to be of the order of a few femtometers, so only the outer few femtometers of a strangelet can carry charge.
The surface tension of strange matter is unknown. If it is smaller than a critical value (a few MeV per square femtometer) then large strangelets are unstable and will tend to fission into smaller strangelets (strange stars would still be stabilized by gravity). If it is larger than the critical value, then strangelets become more stable as they get bigger.
Natural or artificial occurrence
Although nuclei do not decay to strangelets, there are other ways to create strangelets, so if the strange matter hypothesis is correct there should be strangelets in the universe. There are at least three ways they might be created in nature:
- Cosmogonically, i.e. in the early universe when the QCD confinement phase transition occurred. It is possible that strangelets were created along with the neutrons and protons that form ordinary matter.
- High-energy processes. The universe is full of very high-energy particles (cosmic rays). It is possible that when these collide with each other or with neutron stars they may provide enough energy to overcome the energy barrier and create strangelets from nuclear matter. Some identified exotic cosmic ray events, like the Price's event with very low charge-to-mass ratio could have already registered strangelets.
- Cosmic ray impacts. In addition to head-on collisions of cosmic rays, ultra high energy cosmic rays impacting on Earth's atmosphere may create strangelets.
These scenarios offer possibilities for observing strangelets. If there are strangelets flying around the universe, then occasionally a strangelet should hit Earth, where it would appear as an exotic type of cosmic ray. If strangelets can be produced in high-energy collisions, then we might make them at heavy-ion colliders.
At heavy ion accelerators like the Relativistic Heavy Ion Collider (RHIC), nuclei are collided at relativistic speeds, creating strange and antistrange quarks that could conceivably lead to strangelet production. The experimental signature of a strangelet would be its very high ratio of mass to charge, which would cause its trajectory in a magnetic field to be very nearly, but not quite, straight. The STAR collaboration has searched for strangelets produced at the RHIC, but none were found. The Large Hadron Collider (LHC) is even less likely to produce strangelets, but searches are planned for the LHC ALICE detector.
Possible seismic detection
In May 2002, a group of researchers at Southern Methodist University reported the possibility that strangelets may have been responsible for seismic events recorded on October 22 and November 24 in 1993. The authors later retracted their claim, after finding that the clock of one of the seismic stations had a large error during the relevant period.
It has been suggested that the International Monitoring System being set up to verify the Comprehensive Nuclear Test Ban Treaty (CTBT) after entry into force may be useful as a sort of "strangelet observatory" using the entire Earth as its detector. The IMS will be designed to detect anomalous seismic disturbances down to 1 kiloton of TNT (4.2 TJ) energy release or less, and could be able to track strangelets passing through Earth in real time if properly exploited.
Impacts on Solar System bodies
It has been suggested that strangelets of subplanetary i.e. heavy meteorite mass, would puncture planets and other solar system objects, leading to impact (exit) craters which show characteristic features.
If the strange matter hypothesis is incorrect and its surface tension is larger than the aforementioned critical value, then a larger strangelet would be more stable than a smaller one. One speculation that has resulted from the idea is that a strangelet coming into contact with a lump of ordinary matter could convert the ordinary matter to strange matter. This "ice-nine"-like disaster scenario is as follows: one strangelet hits a nucleus, catalyzing its immediate conversion to strange matter. This liberates energy, producing a larger, more stable strangelet, which in turn hits another nucleus, catalyzing its conversion to strange matter. In the end, all the nuclei of all the atoms of Earth are converted, and Earth is reduced to a hot, large lump of strange matter.
This is not a concern for strangelets in cosmic rays because they are produced far from Earth and have had time to decay to their ground state, which is predicted by most models to be positively charged, so they are electrostatically repelled by nuclei, and would rarely merge with them. But high-energy collisions could produce negatively charged strangelet states which live long enough to interact with the nuclei of ordinary matter.
The danger of catalyzed conversion by strangelets produced in heavy-ion colliders has received some media attention, and concerns of this type were raised at the commencement of the Relativistic Heavy Ion Collider (RHIC) experiment at Brookhaven, which could potentially have created strangelets. A detailed analysis concluded that the RHIC collisions were comparable to ones which naturally occur as cosmic rays traverse the solar system, so we would already have seen such a disaster if it were possible. RHIC has been operating since 2000 without incident. Similar concerns have been raised about the operation of the Large Hadron Collider (LHC) at CERN but such fears are dismissed as far-fetched by scientists.
In the case of a neutron star, the conversion scenario seems much more plausible. A neutron star is in a sense a giant nucleus (20 km across), held together by gravity, but it is electrically neutral and so does not electrostatically repel strangelets. If a strangelet hit a neutron star, it could convert a small region of it, and that region would grow to consume the entire star, creating a quark star.
Debate about the strange matter hypothesis
The strange matter hypothesis remains unproven. No direct search for strangelets in cosmic rays or particle accelerators has seen a strangelet (see references in earlier sections). If any of the objects such as neutron stars could be shown to have a surface made of strange matter, this would indicate that strange matter is stable at zero pressure, which would vindicate the strange matter hypothesis. However there is no strong evidence for strange matter surfaces on neutron stars (see below).
Another argument against the hypothesis is that if it were true, all neutron stars should be made of strange matter, and otherwise none should be. Even if there were only a few strange stars initially, violent events such as collisions would soon create many strangelets flying around the universe. Because a single strangelet will convert a neutron star to strange matter, by now all neutron stars would have been converted. This argument is still debated, but if it is correct then showing that one neutron star has a conventional nuclear matter crust would disprove the strange matter hypothesis.
Because of its importance for the strange matter hypothesis, there is an ongoing effort to determine whether the surfaces of neutron stars are made of strange matter or nuclear matter. The evidence currently favors nuclear matter. This comes from the phenomenology of X-ray bursts, which is well explained in terms of a nuclear matter crust, and from measurement of seismic vibrations in magnetars.
- An episode of Odyssey 5 featured an attempt to destroy the planet by intentionally creating negatively charged strangelets in a particle accelerator.
- The BBC docudrama End Day features a scenario where a particle accelerator in New York City explodes, creating a strangelet and starting a catastrophic chain reaction which destroys Earth.
- The story A Matter most Strange in the collection Indistinguishable from Magic by Robert L. Forward deals with the making of a strangelet in a particle accelerator.
- Impact, published in 2010 and written by Douglas Preston, deals with an alien machine that creates strangelets. The machine's strangelets impact the Earth and Moon and pass through.
- The novel Phobos, published in 2011 and written by Steve Alten as the third and final part of his Domain trilogy, presents a fictional story where strangelets are unintentionally created at the Large Hadron Collider and escape from it to destroy the Earth.
- In the 1992 black-comedy novel Humans by Donald E. Westlake, an irritated God sends an angel to Earth to bring about Armageddon by means of using a strangelet created in a particle accelerator to convert the Earth into a quark star.
- In the 2010 film Quantum Apocalypse, a strangelet approaches the Earth from space.
- In the novel The Quantum Thief by Hannu Rajaniemi and the rest of the trilogy, strangelets are mostly used as weapons, but during an early project to terraform Mars, one was used to convert Phobos into an additional "sun".
- E. Farhi and R. Jaffe, "Strange Matter", Phys. Rev. D30, 2379 (1984)
- E. Witten, "Cosmic Separation Of Phases" Phys. Rev. D30, 272 (1984)
- A. Bodmer "Collapsed Nuclei" Phys. Rev. D4, 1601 (1971)
- H. Heiselberg, "Screening in quark droplets", Phys. Rev. D48, 1418 (1993)
- M. Alford, K. Rajagopal, S. Reddy, A. Steiner, "The Stability of Strange Star Crusts and Strangelets", Phys. Rev. D73 114016 (2006) arXiv:hep-ph/0604134
- Shibaji Banerjee, Sanjay K. Ghosh, Sibaji Raha, and Debapriyo Syam, "Can Cosmic Strangelets Reach the Earth?", Phys. Rev. Lett. 85, 1384 – Published 14 August 2000, https://arxiv.org/abs/hep-ph/0006286
- STAR Collaboration, "Strangelet search at RHIC", arXiv:nucl-ex/0511047
- Ellis J, Giudice G, Mangano ML, Tkachev I, Wiedemann U (LHC Safety Assessment Group) (5 September 2008). "Review of the Safety of LHC Collisions" (PDF, 586 KiB). ''Journal of Physics G: Nuclear and Particle Physics. 35, 115004 (18pp). doi:10.1088/0954-3899/35/11/115004. arXiv:0806.3414. CERN record.
- A. Angelis et al., "Model of Centauro and strangelet production in heavy ion collisions", Phys. Atom. Nucl. 67:396-405 (2004) arXiv:nucl-th/0301003
- J. Sandweiss, "Overview of strangelet searches and Alpha Magnetic Spectrometer: When will we stop searching?" J. Phys. G30:S51-S59 (2004)
- D. Anderson et al., "Two seismic events with the properties for the passage of strange quark matter through the earth" arXiv:astro-ph/0205089
- E.T. Herrin et al., "Seismic Search for Strange Quark Nuggets"
- Lance Labun, Jeremey Birrell, Johann Rafelski, "Solar System Signatures of Impacts by Compact Ultra Dense Objects",arXiv:1104.4572
- A. Dar, A. De Rujula, U. Heinz, "Will relativistic heavy ion colliders destroy our planet?", Phys. Lett. B470:142-148 (1999) arXiv:hep-ph/9910471
- W. Busza, R. Jaffe, J. Sandweiss, F. Wilczek, "Review of speculative 'disaster scenarios' at RHIC", Rev. Mod. Phys.72:1125-1140 (2000) arXiv:hep-ph/9910333
- J. Madsen, "Intermediate mass strangelets are positively charged", Phys. Rev. Lett. 85 (2000) 4687-4690 (2000) arXiv:hep-ph/0008217
- J. Madsen "Strangelets in Cosmic Rays", for Proceedings of 11th Marcel Grossmann Meeting, Germany, Jul 2006, arXiv:astro-ph/0612784
- J. Schaffner-Bielich, C. Greiner, A. Diener, H. Stoecker, "Detectability of strange matter in heavy ion experiments", Phys. Rev. C55:3038-3046 (1997), arXiv:nucl-th/9611052
- New Scientist, 28 August 1999: "A Black Hole Ate My Planet"
- Horizon: End Days, an episode of the BBC television series Horizon
- W. Wagner, "Black holes at Brookhaven?" and reply by F. Wilzcek, Letters to the Editor, Scientific American July 1999
- Dennis Overbye, Asking a Judge to Save the World, and Maybe a Whole Lot More, NY Times, 29 March 2008
- "Safety at the LHC".
- J. Blaizot et al., "Study of Potentially Dangerous Events During Heavy-Ion Collisions at the LHC", CERN library record CERN Yellow Reports Server (PDF)
- Alcock, Charles; Farhi, Edward & Olinto, Angela (1986). "Strange stars". Astrophys. J. 310: 261. Bibcode:1986ApJ...310..261A. doi:10.1086/164679.
- J. Friedman and R. Caldwell, "Evidence against a strange ground state for baryons", Phys. Lett. B264, 143-148 (1991)
- J. Madsen, "Strangelets as cosmic rays beyond the GZK-cutoff", Phys. Rev. Lett. 90:121102 (2003) arXiv:stro-ph/0211597
- S. Balberg, "Comment on 'strangelets as cosmic rays beyond the Greisen-Zatsepin-Kuzmin cutoff'", Phys. Rev. Lett. 92:119001 (2004), arXiv:astro-ph/0403503
- J. Madsen, "Reply to Comment on Strangelets as Cosmic Rays beyond the Greisen-Zatsepin-Kuzmin Cutoff", Phys. Rev.Lett. 92:119002 (2004), arXiv:astro-ph/0403515
- J. Madsen, "Strangelet propagation and cosmic ray flux", Phys. Rev. D71, 014026 (2005) arXiv:astro-ph/0411538
- A. Heger, A. Cumming, D. Galloway, S. Woosley, "Models of Type I X-ray Bursts from GS 1826-24: A Probe of rp-Process Hydrogen Burning", arXiv:0711.1195
- A. Watts and S. Reddy, "Magnetar oscillations pose challenges for strange stars", MNRAS, 379, L63 (2007) arXiv:astro-ph/0609364
- Odyssey 5: Trouble with Harry, an episode of the Canadian science fiction television series Odyssey 5 by Manny Coto (2002)
- Holden, Joshua (May 17, 1998). "The Story of Strangelets". Rutgers. Retrieved 2010-04-01.
- Fridolin Weber (2004). "Strange Quark Matter and Compact Stars". Progress in Particle and Nuclear Physics. 54: 193–288. arXiv: . Bibcode:2005PrPNP..54..193W. doi:10.1016/j.ppnp.2004.07.001.
- Jes Madsen (1998). "Hadrons in Dense Matter and Hadrosynthesis". Lect.Notes Phys. Lecture Notes in Physics. 516: 162–203. arXiv: . doi:10.1007/BFb0107314. ISBN 978-3-540-65209-0. | <urn:uuid:c4cceade-dcf1-4286-beef-45ee39fc6248> | 3.390625 | 4,046 | Knowledge Article | Science & Tech. | 56.708988 | 95,558,306 |
A View from Katherine Bourzac
Sculpting Tissues with Magnets
Cells treated with magnetic nanoparticles can be held in tissue-like 3-D shapes.
Being able to grow more realistic liver, heart, and other tissues in the lab could provide a new lease on life for patients waiting on the transplant list–and lead to more realistic systems for testing drugs. But tissue engineers have found that mimicking these complex, three-dimensional structures in the lab is difficult. Part of what’s holding them up are flat, two-dimensional tissue culture systems that grow cells in an environment very different from that inside the body.
Now researchers at Rice University and the MD Anderson Cancer Center in Houston have developed a simple way to make cells form 3-D structures. They developed a gel made up of a polymer, iron oxide nanoparticles, and engineered viruses called phage. When cells are added to this mixture, the phage cause them to absorb the magnetic particles. The Houston group showed that they could use a weak magnet to hold magnetized brain cancer cells in a 3-D suspension. Gene-expression studies showed that these suspended cells behave more naturally than a control group grown on a conventional flat surface: the cancer cells were producing a mix of proteins very similar to what they produce in the body. These results are described in Nature Nanotechnology this week.
The magnetizing gel has been licensed to a startup company, Nano3D Bioscience, which will run tests to compare the technology other methods for making 3-D tissues.
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Language: Chinese with English summary and keys
Strongylata is a very important group within the Class Nematoda. There are a lot of species of this group parasitizing domestic animals and man. A total of 178 species belonging to 3 superfamilies, 12 families and 63 genera of Strongylata are dealt with in this issue. For each species included in this volume, the following topics are treated: scientific nomenclature, description of male, female or both, the hosts, and the geographical distribution, with emphasis on the distributional localities in China. Life history and epidemiology are also given to some important species.
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Discovered from England by the tireless observer Sir William Herschel on 20 November 1784, the bright star cluster NGC 2367 lies about 7000 light-years from Earth in the constellation Canis Major. Having only existed for about five million years, most of its stars are young and hot and shine with an intense blue light. This contrasts wonderfully in this new image with the silky-red glow from the surrounding hydrogen gas.
Open clusters like NGC 2367 are a common sight in spiral galaxies like the Milky Way, and tend to form in their host's outer regions. On their travels about the galactic centre, they are affected by the gravity of other clusters, as well as by large clouds of gas that they pass close to.
This rich view of an array of colorful stars and gas was captured by the Wide Field Imager (WFI) camera, on the MPG/ESO 2.2-meter telescope at ESO's La Silla Observatory in Chile. It shows a young open cluster of stars known as NGC 2367, an infant stellar grouping that lies at the center of an immense and ancient structure on the margins of the Milky Way.
Credit: ESO/G. Beccari
Because open clusters are only loosely bound by gravity to begin with, and because they constantly lose mass as some of their gas is pushed away by the radiation of the young hot stars, these disturbances occur often enough to cause the stars to wander off from their siblings, just as the Sun is believed to have done many years ago. An open cluster is generally expected to survive for a few hundred million years before it is completely dispersed.
In the meantime, clusters serve as excellent case studies for stellar evolution. All the constituent stars are born at roughly the same time from the same cloud of material, meaning they can be compared alongside one another with greater ease, allowing their ages to be readily determined and their evolution mapped.
Like many open clusters, NGC 2367 is embedded within an emission nebula), from which its stars were born. The remains show up as wisps and clouds of hydrogen gas, ionised by the ultraviolet radiation being emitted by the hottest stars. What is more unusual is that, as you begin to pan out from the cluster and its nebula, a far more expansive structure is revealed: NGC 2367 and the nebula containing it are thought to be the nucleus of a larger nebula, known as Brand 16, which in turn is only a small part of a huge supershell, known as GS234-02.
The GS234-02 supershell lies towards the outskirts of our galaxy, the Milky Way. It is a vast structure, spanning hundreds of light-years. It began its life when a group of particularly massive stars, producing strong stellar winds, created individual expanding bubbles of hot gas.
These neighbouring bubbles eventually merged to form a superbubble, and the short life spans of the stars at its heart meant that they exploded as supernovae at similar times, expanding the superbubble even further, to the point that it merged with other superbubbles, which is when the supershell was formed. The resulting formation ranks as one of the largest possible structures within a galaxy.
This concentrically expanding system, as ancient as it is enormous, provides a wonderful example of the intricate, interrelated structures that are sculpted in galaxies by the lives and deaths of stars.
ESO is the foremost intergovernmental astronomy organisation in Europe and the world's most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world's largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become "the world's biggest eye on the sky".
Photos of the MPG/ESO 2.2-metre telescope - http://www.
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Richard Hook | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
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17.07.2018 | Information Technology
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Shrub encroachment is a global phenomenon. Both the causes and consequences of shrub encroachment vary regionally and globally. In the southwestern US a common native C3 shrub species, creosotebush, has invaded millions of hectares of arid and semi-arid C4-dominated grassland. At the Sevilleta LTER site, it appears that the grassland-shrubland ecotone is relatively stable, but infill by creosotebush continues to occur. The consequences of shrub encroachment have been and continue to be carefully documented, but the ecological drivers of shrub encroachment in the southwestern US are not well known.
The Sevilleta LTER and University of New Mexico have received a five year grant from the National Science Foundation for the project entitled, "Grassland sensitivity to climate change at local to regional scales: assessing the roles of ecosystem attributes versus environmental context." The overarching goal of this research is to determine the consequences of chronic drought on biodiversity and ecosystem services in grasslands across precipitation and temperature gradients.
The distribution, structure and function of mesic savanna grasslands are strongly driven by fire regimes, grazing by large herbivores, and their interactions. There is evidence to suggest, however, that fire and grazing influence savanna grassland structure and function differently in South Africa (SA) compared to North America (NA). These differences have been attributed to the contingent factors of greater biome age, longer evolutionary history with fire and grazing, reduced soil fertility, and greater diversity of plants and large herbivores in SA.
The varied topography and large elevation gradients that characterize the arid and semi-arid Southwest create a wide range of climatic conditions - and associated biomes - within relatively short distances. This creates an ideal experimental system in which to study the effects of climate on ecosystems. Such studies are critical givien that the Southwestern U.S. has already experienced changes in climate that have altered precipitation patterns (Mote et al. 2005), and stands to experience dramatic climate change in the coming decades (Seager et al. 2007; Ting et al. 2007).
This data base contains taxonomic and ecological information for the plant species on the Sevilleta National Wildlife Refuge.
The purpose of this study is to monitor the fruit production of three woody tree species that occur on the Sevilleta National Wildlife Refuge (NWR). Two monoecious species, Pinus edulis and Quercus turbinella, are assessed, as is a dioecious species, Juniperus monosperma. In August, fruit production is estimated for the three species at five sites within the Sevilleta NWR.
The germination rate of creosote (Larrea tridentata) on the Sevilleta appears to be very low. During the early years of the LTER project it was attempted to quantify such germination through the use of seedling plots which were monitored on a bi-annual basis (spring and fall). During the period from 1989 through 1992 there were no creosote seedling that germinated on the monitoring plots.
Plant phenology or life-history pattern changes seasonally as plants grow, mature, flower, and produce fruit and seeds. Plant phenology follows seasonal patterns, yet annual variation may occur due to annual differences in the timing of rainfall and ambient temperature shifts. Foliage growth and fruit and seed production are important aspects of plant population dynamics and food resource availability for animals.
This data set includes precipitation chemisty from 20 funnel collectors on the Sevilleta National Wildlife Refuge (NWR). Variables measured include volume, NO3-N, NH4-N, SO4, Cl, Na, K, Ca, Mg, and PO4. The sample interval depends on the frequency of significant precipitations events. Field collection of precipitation chemistry samples occurred as soon after a significant precipitation event as possible (usually within a week after the event).
Most research on microbial soil crusts has been concentrated in the cold desert grasslands of the Colorado Plateau and the Basin and Range region of the western United States. Relatively little is known about the microbial communities of soils of the warm, semi-arid grassland region of the southwestern United States.
Most recent studies of microbial processes and microbial ecology at the Sevilleta National Wildlife Refuge (SNWR) have focused on the semiarid grassland biome. These studies can be broadly classified into process, phylogenetic and modeling categories.
This project was designed to examine the long-term response of semi-arid vegetation communities to the removal of dominant species. One dominant species representing each of the three major biomes occurring at the Sevilleta National Wildlife Refuge was selected for removal from the sampled plots. These species included: Bouteloua gracilis (blue grama), the characteristic dominant grass of shortgrass steppe, Bouteloua eriopoda (black grama), a dominant grass of Chihuahuan D
In 2005, root ingrowth donuts were established on the Sevilleta NWR to monitor below ground biomass under different conditions and to compare estimates of root production between root ingrowth donut and mini-rhizonton tube methods at four sites on the east side of the refuge. Soil and roots are collected from the "donuts" annually in late fall after the growing season, and structures are then re-established in situ for consecutive harvests for the following years. Each structure allows roots to be harvested at two depths (0-15 and 15-30cm) to estimate root production, or "below ground net primary productivity".
This project was initiated to evaluate temporal and spatial dynamics across vegetation transition zones. Current research includes an investigation into how the extent of Bouteloua eriopoda (black grama) and B. gracilis (blue grama) cover changes over time in relation to meterological conditions. Likewise, the dynamics of the forb community in relation to shifting climatic conditions is being explored.
This study originated with the objective of parameterizing riparian evapotranspiration (ET) in the water budget of the Middle Rio Grande. We hypothesized that flooding and invasions of non-native species would strongly impact ecosystem water use. Our objectives were to measure and compare water use of native (Rio Grande cottonwood, Populus deltoides ssp.
Fire is a common agent of disturbance in grassland ecosystems. The removal of cattle from the Sevilleta National Wildlife Refuge (SNWR) after 1973 resulted in an increased number of lightning-initiated wildfires which left a mosaic of burned patches across the landscape. Prior to 2002, lightning-initiated wildfires were actively suppressed, but have since been allowed to burn. The effects of fire on post-grazing vegetation have been addressed in several studies. Fire effects have also bee
The late Dr. Clifford S. Crawford established the Sevilleta’s Schoolyard LTER Program which funds an educational outreach program known locally as the Bosque Ecosystem Monitoring Program (BEMP). The major focus of the program is to monitor key indicators of structural and functional change in the Middle Rio Grande riparian cottonwood forest ('bosque') corridor through central New Mexico, including the Sevilleta National Wildlife Refuge.
Two of the most pervasive human impacts on ecosystems are alteration of global nutrient budgets and changes in the abundance and identity of consumers. Fossil fuel combustion and agricultural fertilization have doubled and quintupled, respectively, global pools of nitrogen and phosphorus relative to pre-industrial levels. In spite of the global impacts of these human activities, there have been no globally coordinated experiments to quantify the general impacts on ecological systems.
Humans are creating significant global environmental change, including shifts in climate, increased nitrogen (N) deposition, and the facilitation of species invasions. A multi-factorial field experiment is being performed in an arid grassland within the Sevilleta National Wildlife Refuge (NWR) to simulate increased nighttime temperature, higher N deposition, and heightened El Niño frequency (which increases winter precipitation by an average of 50%).
The Small Mammal Population Study (Sev008) is a baseline SevLTER dataset initiated in 1989 with the inception of the project in order to examine the spatial and temporal distribution of populations. This research is coupled with measures of primary productivity, and climate to ascertain: 1) the influence of climate on population dynamics; and 2) the role of animals as trophic drivers regulating vegetation dynamics.
The Sevilleta Gunnison’s Prairie Dog (Cynomys gunnisoni) Restoration project examines keystone consumer (herbivore) effects on grasslands in concert with ecological restoration of a “species of greatest conservation need in New Mexico” (NMG&F Comprehensive Wildlife Conservation Strategy, 2007). SevLTER partners directly with US Fish & Wildlife on the Sevilleta National Wildlife Refuge and non-profit Prairie Dog Pals on this ambitious effort to re-establish Gunnison’s prairie dogs to blue grama-dominated (Bouteloua gracilis) Great Plains grassland at the foothills of the Los Pinos Mountains on Sevilleta.
Net primary production (NPP) is a fundamental ecological variable describing rates of carbon consumption and fixation. Estimates of NPP are important in understanding the spatial and temporal responses of communities to a wide range of ecological processes including decomposition, fertility, and producer-consumer dynamics. Net primary production is influenced by many factors, including temperature, soil nutrient content, soil texture, pollination, herbivory, and granivory.
Increased atmospheric CO2 concentrations caused by fossil fuel consumption are affecting global climate, increasing temperatures and precipitation variability in many regions. Such changes in climate can exceed the physiological tolerances of existing long-lived plant species or, alternatively, make conditions more favorable, increasing species productivity and abundance.
The Sevilleta’s climate is characterized by an intriguing combination of abundant sunshine, low humidity, and high variability for most meteorological factors. The site exists at the boundary between several major air mass zones that contribute to the dynamics of the local climate.
The Monsoon Rainfall Manipulation Experiment (MRME) enables the quantification of changes in the structure and function of a semiarid grassland ecosystem that have been caused by increased rainfall variability. Variability in precipitation affects the timing and duration of the pulses of soil moisture that drive primary productivity, community composition, and ecosystem processes in semiarid grasslands.
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posted by Mi
you reacted magnesium with a hydrochloric acid aqueous solution and hydrogen gas was produced. Let's say that you collected the gas given off by the reaction and measured it's pressure as 102.1 kPa. If the vapor pressure of water is 16.2 kPa at this temperature, then what is the pressure of the hydrogen gas?
stop the duplicate posts. | <urn:uuid:c7442e42-a516-4d41-893e-1ad1e86f3ce9> | 3.40625 | 80 | Q&A Forum | Science & Tech. | 69.589936 | 95,558,396 |
Light. Previous knowledge. Tell me one of your experience or vocabulary about light. What is light?. energy. Light is _______. Light travels in a _______ . Light consists of particles called _________. wave. photons. Light Spectrum. White light can be separated into 6 colors.
What characteristics of light determines the amount of energy carried by a photon of the light?
Which part of a hand is opaque to x-rays? Skin or bone
Which part of a hand is transparent to x-rays? Skin or bone
In water light travels at 75% of its speed or 0.75 c.
If a straight line is drawn perpendicular to the reflecting surface at the point when the incoming ray strikes the surface, the angle of incidence and the angle of reflection can be defined with respect to the line.
http://www.physicsclassroom.com/class/light/u12l1e.cfm for further information.
The process that separate waves with electric-field oscillations in the vertical direction from those in the horizontal direction, producing a beam of light with electric-field waves oriented in the same direction. | <urn:uuid:4fac1375-b8fd-4fce-9492-e22564325f4c> | 3.5625 | 234 | Content Listing | Science & Tech. | 68.5625 | 95,558,400 |
Climate Change: Coal Plant Mitigation and Replacement Strategies
Scientific American has a very useful article about the strategies available to make serious carbon emissions from coal-based electric generating plants. Some highlights:
Power plants in the U.S. burned more than one billion tons of coal in 2006, according to the U.S. Department of Energy's Energy Information Administration. . . .These ancient mountains hold high-quality bituminous coal, which fuels the aging coal-fired power plants that supply roughly 50 percent of the nation's electricity and more than 40 percent of the nation's emissions of carbon dioxide—the leading greenhouse gas. . . .
"Certainly for the next several decades, the majority of electricity will be generated by fossil fuels in a fairly conventional way," says Bill Moomaw, an international energy policy expert at Tufts University's Fletcher School of Law and Diplomacy, primarily because it is cheap and readily available. "If we're going to continue to use coal we're going to have to have some way of reducing the carbon dioxide." As a result, the IPCC summary notes that carbon capture and storage—trapping the carbon dioxide before it escapes from the smokestack and pumping it underground—is a likely technology solution for mitigating climate change, along with a variety of other options. "There is no silver bullet," says Harlan Watson, senior climate negotiator for the U.S.
But carbon capture and storage will play a key role as coal continues to supply a significant portion of world energy supply and, unfortunately, it has yet to be demonstrated on any power plant anywhere. The U.S. Department of Energy (DOE) has at least 20 pilot projects to investigate it, according to Stephen Eule, DOE's director of the climate change technology program, but none have applied it on a commercial scale. A variety of techniques, including passing the remnants of coal combustion through an ammonium carbonate solution or separating purified CO2 from gasified coal, are possible—at a cost. "There is no plant that integrates gasification with capture and sequestration," says physicist Ernest Moniz of the Massachusetts Institute of Technology, who co-chaired a report on the future of coal. But "gasification looks today to be the lowest cost option with carbon capture."
That primary cost is in energy that gets used to capture the carbon—roughly 40 percent of the power a plant can produce—as well as to pressurize it and pump it underground. "In general terms, you are talking about a 50 percent increase in the cost of coal and maybe a 25 percent increase in the retail residential price of coal-fired electricity," Moniz says. "For a 600-megawatt power plant, in order to capture most of the CO2 and sequester it for the 50-year life of the plant, you're talking about one billion barrels of supercritical CO2. That's a pretty big reservoir."
. . .
There are other technologies available, such as using algae to capture the waste greenhouse gases from power plants and turning it into diesel or other fuels. "The amount of CO2 that you capture [with algae] is very high and the amount of biofuel created per acre is incredibly greater than you can do with corn or even sugarcane," Tufts's Moomaw says. "The problem is it only works in the daytime." Alternative forms of power production, such as wind or solar, remain a small—albeit fast-growing—portion of world electricity supply. Even nuclear power is unlikely to play a major role in fighting climate change. "By 2030, we might be seeing something around 18 percent of power being generated by nuclear rather than the 16 percent we see today," Moomaw adds. "There are so many issues around nuclear power, we don't see it as being the answer to global warming and the electricity sector."
Read it all.
Unfortunately, it appears that the country may be increasing, rather than decreasing its reliance on coal. The Christian Science Monitor reports that at least eight electrical transmissionlines are being constructed with the aim of moving coal-based electricity to the Northeast. the result willlikely be an increased reliance on coal:
"This is really all about transferring inexpensive coal power into areas of the country that have higher-priced electricity," says Mark Brownstein, a managing director in the climate and air program at New York-based Environmental Defense. "These parts of the country have taken a stand to reduce greenhouse-gas emissions.... So these lines become pipelines that undo policy positions that the Northeast has taken." | <urn:uuid:573fc494-f85a-47fc-ab7c-d6fe82778bd8> | 3.078125 | 931 | Personal Blog | Science & Tech. | 42.79875 | 95,558,401 |
Super-sensitive microwave detectors, built at the National Institute of Standards and Technology (NIST), may soon help scientists find out.
The new sensors, described today at the American Physical Society (APS) meeting in Denver, were made for a potentially ground-breaking experiment* by a collaboration involving NIST, Princeton University, the University of Colorado at Boulder, and the University of Chicago.
Although NIST is best known for earthbound measurements, a long-standing project at NIST’s Boulder campus plays a critical role in the study of the cosmic microwave background (CMB)—the faint afterglow of the Big Bang that still fills the universe. This project previously built superconducting amplifiers and cameras for CMB experiments at the South Pole, in balloon-borne observatories, and on the Atacama Plateau in Chile.
The new experiment will begin approximately a year from now on the Chilean desert and will consist of placing a large array of powerful NIST sensors on a telescope mounted in a converted shipping container.
The detectors will look for subtle fingerprints in the CMB from primordial gravitational waves—ripples in the fabric of space-time from the violent birth of the universe more than 13 billion years ago. Such waves are believed to have left a faint but unique imprint on the direction of the CMB’s electric field, called the “B-mode polarization.” These waves—never before confirmed through measurements—are potentially detectable today, if sensitive enough equipment is used.
“This is one of the great measurement challenges facing the scientific community over the next 20 years, and one of the most exciting ones as well,” said Kent Irwin, the NIST physicist leading the project.
If found, these waves would be the clearest evidence yet in support of the “inflation theory,” which suggests that all of the currently observable universe expanded rapidly from a subatomic volume, leaving in its wake the telltale cosmic background of gravitational waves.
“The B-mode polarization is the most significant piece of evidence related to inflation that has yet to be observed,” said Ki Won Yoon, a NIST postdoctoral scholar who will describe the project at the APS meeting. “A detection of primordial gravitational waves through CMB polarization would go a long way toward putting the inflation theory on firm ground.”
The data also could provide scientists with insights into different string theory models of the universe and other “unified” theories of physics.
These types of experiments can only be done by studying the universe as a whole, because the particles and electromagnetic fields at the beginning of the inflationary epoch were roughly 10 billion times hotter than the energies attainable by the most powerful particle colliders on Earth today. At this energy scale, fundamental forces now identified as separate are predicted to merge.
“The universe is a physics lab,” Irwin said. “If you look far away, you are actually looking back in time, potentially observing interactions that occurred at energy levels forever out of reach of terrestrial experiments.”
Recent studies of the CMB have focused on measuring slight spatial variations in temperature or power that existed about 380,000 years after the Big Bang. These patterns of radiation allow scientists to characterize the early distributions of matter and energy that evolved into the stars and galaxies of today.
By comparing the measurements to predictions made by various theories, scientists have added to the authoritative history of the universe, narrowing down, for instance, its age (13.7 billion years).
By contrast, the new NIST detectors are designed to measure not only temperature but also the polarization. The B-mode polarization signals may be more than a million times fainter than the temperature signals.
To detect such subtle patterns, the NIST detectors will collect significant amounts of radiation efficiently, and will be free of moving parts and traditional sources of systematic error, such as vibration and magnetic interference, Irwin said. In addition, advanced signal processing and error control will be needed.
The new sensors are prototypes for NIST polarimeter arrays that will greatly increase the sensitivity of future experiments by building thousands of detectors into monolithic units that can be deployed in cryogenic telescope cameras. The new NIST detectors may also have applications closer to home, such as in reducing glare in advanced terahertz imaging systems for detecting weapons and contraband.
As a non-regulatory agency of the U.S. Department of Commerce, NIST promotes U.S. innovation and industrial competitiveness by advancing measurement science, standards and technology in ways that enhance economic security and improve our quality of life.
*Atacama B-mode Search (ABS): Scientific Motivations and Design Overview, Sheraton Denver Hotel, Plaza Court 2, Saturday, May 2, 2009, 1:30 – 1:42 p.m.
Laura Ost | Newswise Science News
Further reports about: > B-mode polarization > Big Bang > CMB > Inflationary Universe > NIST > NIST sensors > Super-Sensors > Super-sensitive microwave detectors > Universe > balloon-borne observatories > earthbound measurements > gravitational waves > magnetic field > subatomic volume > superconducting amplifiers > terrestrial experiments
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
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20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
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Reed (Phragmites australis) is a natural biological material that has great potential as reinforcing material in bio-composites. In order to evaluate the potential of reed stalk for reinforcement, the microstructure, elemental composition, microfibril angle (MFA), and mechanical properties of fiber cell walls were investigated by means of scanning probe microscopy (SPM), energy dispersive analysis of X-rays (EDAX), X-ray diffraction (XRD), and nanoindentation, respectively. The effects of elemental composition and microfibril angle of reed fibers on the mechanical properties were also considered. The results indicated that reed fiber cells have a multilayered structure. The observed increase in lignin content and decrease in MFA may contribute to the increase of mechanical properties. The elastic modulus and hardness of fibers in the upper part of the reed stalk were higher than those of the lower part. Based on nanoindentation results found in the literature, reed fibers have higher elastic modulus and hardness than poplar and spruce fibers. | <urn:uuid:2cbd7a01-9a6c-4604-8d38-55c141b70d14> | 3.09375 | 226 | Academic Writing | Science & Tech. | 14.87 | 95,558,419 |
The world of quantum physics is one of the most amazing things in the world. It holds the secrets to all of the universe, and within a few particles, the story of the entire universe. This simple fact inspires two reactions within people. For those who are educated, and willing to understand, it is a beautiful world, one which harbors infinite amounts of knowledge. The other reaction is by those whose first choice is to instantly jump to a state of ignorance and fear. These people choose to make up insane theories about all of the awful things that scientists do, hence ideas like chemtrails, and the LHC creating black holes. As I said earlier, my intention with writing this is to help reduce this level of ignorance, and to shed some light on the truth. Even if it only helps 1 person, my job is done. Let us continue our adventure into the world of quantum physics with: Unlocking The Secrets of The Standard Model Part 3: Gauge Bosons.
According to wikipedia, a gauge boson is described as: “Any (bosonic) particle that carries any of the fundamental forces of nature. This means that the particles will include one of the 4 known fundamental forces. These forces are: Electromagnetic, Gravity, Strong Nuclear Force, and Weak Nuclear Force. The class of gauge bosons contains 4 particles: The gluon, the photon, the Z boson, and the W boson. Each of these particles helps to enforce or carry one of the fundamental forces of nature, other than gravity. Gravity currently has no known particle that causes it to work, instead it is explained through Einstein’s General Theory of Relativity. It is theorized that there may be a gauge boson that carries gravity, but it is not yet known whether it truly exists. This theoretical particle is often referred to as the “graviton.” All of these particles are bosonic, which means that they have a spin of 1.
The first boson on the list is the gluon. The gluon does the work of the strong nuclear force, specifically between quarks. It has a near zero mass, and is considered to be one of the smallest particles in the known model. The gluon tends to hang out in a field around quarks, forcing them to stick to each other, and form a particle. Since gluons execute the strong nuclear force, they are the only thing that keeps similarly charged quarks from repelling each other. The gluon has no inherent charge, which makes it easier for it to interact with itself, and other charged particles.
The second boson on the list is the photon. The photon has a special place in the heart of science, specifically because it can be used to explain almost everything in the universe. The photon is the only known particle with a mass of 0, which gives it the ability to pass through almost any object without resistance. The best way to explain a photon is by thinking of it as a packet of energy, or light. The photon is the particle that produces and holds energy, and is responsible for the electromagnetic force. The photon is also the particle that produced the electromagnetic spectrum, which includes visible light. It is arguably the most important particle ever discovered.
The W and Z bosons are the last bosons on this list. They are usually lumped together, simply because they mediate the same force: The Weak Nuclear Force. The W boson can be either negatively or positively charged, each differently charge version being the opposites anti-particle. I will delve deeper into antimatter and exotic forces in another entry. The Z boson is neutrally charged, and is its own antiparticle. The Z boson is special, considering the fact that it is the only particle to be its own antiparticle. The W and Z bosons are mediators of some of the properties of the weak force that include neutrinos. Since this is an entry level explanation, I will simply say that they are extremely technical and complicated. If you have more interest in it, you can look up “Nuclear Transmutation,” and “Neutrino/Positron Absorption/Emission.” W and Z bosons are extremely massive, weighing more than an entire iron atom. This causes the range of the weak nuclear force to be limited in range. These bosons are most commonly known for the integral role that they play in neutron decay, specifically that of beta decay of the element cobalt-60.
That about covers it for the gauge bosons. The next topic we will be covering is the newly discovered and highly controversial Higgs Boson, also known as the “God Particle.” That will be the last entry about elementary particles, and after that, we will move on to different concepts, such as fundamental forces, and antimatter. Until then, everybody! | <urn:uuid:97493702-4078-4c6b-978b-076c6195f313> | 2.890625 | 1,012 | Personal Blog | Science & Tech. | 49.419036 | 95,558,431 |
Ice Age and Thickness - Total Operational Weather Readiness - Satellites (TOWR-S)
VIIRS Ice Age / Thickness
Frequently Asked Questions about the VIIRS Ice Age / Thickness Product
1) What is this product?
This product has two outputs of interest to the forecaster. The first is the Ice Thickness, which is defined as the total vertical length of the ice under and above the water surface. The range of values to be expected is from 0 to 3.0 meters.
The second is the Ice Age, which has eight possible outputs.:
1) "New"is defined as recently formed ice which includes frazil ice, grease ice, slush and shuga. These types of ice are composed of ice crystals which are only weakly frozen together (if at all) and have a definite form only while they are afloat, usually less than 2 cm.
2) "Nilas" is defined a thin elastic crust of ice, easily bending on waves and swell and under pressure growing in a pattern of interlocking “fingers” (finger rafting). Nilas has a matte surface and is
up to 10 cm in thickness and may be subdivided into dark nilas and light nilas.
3) "Grey" is defined as your ice 10-15 cm thick. Less elastic than nilas and breaks on swell. Usually rafts under pressure.
4) "Grey-White" is defined as young ice 15-30 cm thick. Under pressure it is more likely to ridge than to raft.
5) "First-Year Thin" is defined as first-year ice of not more than one winter's growth, 30-70 cm thick.
6) "First-Year Medium" is defined as first-year ice 70-120 cm thick.
7) "First-Year Thick" is defined as first year ice 120-180 cm thick.
8) "Older Ice" is defined as sea ice which has survived at least one summer's melt. Topographic features generally are smoother than first-year ice, and more than 180 cm thick.
This product is useful when looking as shipping routes through sea ice because the type of ice can dictate whether or not a ship can successfully navigate the area. Seasonal ice-melt/ice-growth monitoring can also be performed using this product.
2) How often do I receive this data?
The S-NPP satellite is part of the Afternoon Train (A-Train) of satellites. It crosses your area at ~1:30am and ~1:30pm local time every day.
3) How do I display this product in AWIPS-II?
4) How do I interpret the color maps associated with this product?
5) What should I use in conjunction with this product to produce a better forecast?
Ice flow forecast models and other independent ice analyses.
6) How is this product created?
Physical and statistical approaches are employed to estimate sea and lake ice thickness and age. One-dimensional Thermodynamic Ice Model (OTIM) based on the surface energy budget, containing all components of the surface energy budget has been developed to estimate sea and lake ice thickness. Then based on the knowledge of ice thickness, ice is classified into open water, new/fresh ice, grey ice, grey-white ice, thin first year ice, medium first year ice, thick first year ice, and multi-year or older ice. It inevitably involves parameterizations and/or assumptions of the sea and lake ice and associated snow characteristics, such as ice and snow conductivities, densities, and transmittances. 1
The difficult task for any ice thickness and age estimation based on the thermodynamic theory is to exploit not only ice and snow micro-physical properties which are closely related to ice and snow types and contents but also its environmental conditions such as humidity, air temperature, wind, cloud cover, water salinity and current. 1
1NOAA/NESDIS/STAR. NOAA NESDIS Center for Satellite Applications and Research: Algorithm Theoretical Basis Document: ABI and VIIRS Ice Thickness and AGE. v1.0, December 17, 2015. | <urn:uuid:7cd8ec98-dd7c-4297-a41c-7b65dbf0a9cd> | 3.421875 | 872 | FAQ | Science & Tech. | 53.155996 | 95,558,452 |
- University of Guelph
- Lucid via Discover Life
- Antennae long, slender
- Mouthparts mandibulate, prognathous
- Body long, cylindrical
- Prothorax shorter than meso- or metathorax
- Leg segments long and slender
- Tarsi 5-segmented
- Wings often reduced or absent
- Cerci short, unsegmented
Common in tropical and subtropical climates where they are found living on their host plants.
|Number of Families
|Number of Species
The leaf and stick insects are sometimes grouped as a family or suborder of Orthoptera. All species are
herbivores. As the name "walkingstick" implies, most phasmids are slender, cylindrical, and cryptically
colored to resemble the twigs and branches on which they live. Members of the family Timemidae
(=Phyllidae) bear a strong resemblance to leaves: abdomens are broad and flat, legs have large lateral
extensions, and coloration is primarily brown, green, or yellow. Most walkingsticks are slow-moving
insects, a behavior pattern that is consistent with their cryptic lifestyle. In a few tropical species, the adults
have well-developed wings, but most phasmids are brachypterous (reduced wings) or secondarily
wingless. Stick insects are most abundant in the tropics where some species may be up to 30 cm (12
inches) in length. Females do not have a well-developed ovipositor so they cannot insert their eggs into
host plant tissue like most other Orthoptera. Instead, the eggs are dropped singly onto the ground,
sometimes from great heights.
A Few Facts:
- Phasmid eggs often resemble seeds. The eggs may remain dormant for over a year before hatching.
- In some parts of the tropics, stick insects may be so abundant that eggs falling out of the trees may sound like rain on a tin roof.
- Some walkingsticks are sold as pets. They are easy to rear if kept in a warm environment with fresh foliage from their host plant.
- Glands located on the thorax of many species can produce a foul-smelling liquid that repels predators.
- When attacked by a predator, the legs of some phasmids may separate from the body (autotomy).
Some species can even regenerate lost legs. These are the only insects able to regenerate body parts.
- Several species produce offspring from unfertilized eggs (parthenogenesis). Males may be uncommon or unknown.
- Some phasmids change color with changes in temperature, humidity, or light intensity.
Pigment granules in the epidermis disperse at night or on cool days, darkening the cuticle and absorbing more heat.
This page was constructed from Casandra Lloyd's (Ecology Major, UGA) original Phasmatodea page.
Top | See original
Following modified from University of Guelph
Order - PHASMATODEA
= apparition, phantom)
stick insects, leaf insects, walking stick insects
Warmer parts of world, especially the tropics
Although diverse in the tropics, the Phasmatodea is a small group in North America. The only northeastern species is illustrated here.
To Go to Back to Main Menu
ERROR -- Need to remove recursive link: http://www.discoverlife.org/nh/id/lucid/Insect_orders/html/Phasmatodea.html Lucid via Discover Life
Updated: 2018-07-16 16:30:14 gmt | <urn:uuid:d12783d8-5d05-4d1e-83c8-af1192d621c1> | 3.546875 | 774 | Knowledge Article | Science & Tech. | 38.830246 | 95,558,459 |
Polymeric solid surfaces were prepared by a radiation-induced graft copolymerization technique using various mixtures of 2-hydroxyethyl methacrylate (HEMA) and ethyl methacrylate (EMA). Low-density polyethylene (PE) films were used as graft substrates. Contact angles on these polymeric surfaces were determined in air and under water. The critical surface tension (γc) of each polymeric surface in air was estimated by the Zisman method. Geometric mean and harmonic mean approximation methods were utilized to estimate the dispersion force contribution (γsd) and the polar contribution (γsp) to the total surface free energy (γs) from contact angle data in air. The geometric mean approximation was also used to estimate γsd′and γsp′from contact angles under water. The calculated values of γsd, γspare strongly dependent on the pair of liquids chosen for the calculation regardless of the approximation adopted. The values of γs, calculated as the sum of γsdand γsp, are close to the γcvalues and are less dependent on the pair of liquids used. A comparison of the ratio γsd/γspfor the same surface in air and under water suggests that major polymer chain conformational changes occur, particularly with respect to the hydroxyl side chain, when such surfaces are immersed in water. © 1981.
Mendeley saves you time finding and organizing research
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Effects of common groundwater ions on chromate removal by magnetite: importance of chromate adsorption
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Reductive precipitation of hexavalent chromium (Cr(VI)) with magnetite is a well-known Cr(VI) remediation method to improve water quality. The rapid (<a few hr) reduction of soluble Cr(VI) to insoluble Cr(III) species by Fe(II) in magnetite has been the primary focus of the Cr(VI) removal process in the past. However, the contribution of simultaneous Cr(VI) adsorption processes in aged magnetite has been largely ignored, leaving uncertainties in evaluating the application of in situ Cr remediation technologies for aqueous systems. In this study, effects of common groundwater ions (i.e., nitrate and sulfate) on Cr(VI) sorption to magnetite were investigated using batch geochemical experiments in conjunction with X-ray absorption spectroscopy.
In both nitrate and sulfate electrolytes, batch sorption experiments showed that Cr(VI) sorption decreases with increasing pH from 4 to 8. In this pH range, Cr(VI) sorption decreased with increasing ionic strength of sulfate from 0.01 to 0.1 M whereas nitrate concentrations did not alter the Cr(VI) sorption behavior. This indicates the background electrolyte specific Cr(VI) sorption process in magnetite. Under the same ionic strength, Cr(VI) removal in sulfate containing solutions was greater than that in nitrate solutions. This is because the oxidation of Fe(II) by nitrate is more thermodynamically favorable than by sulfate, leaving less reduction capacity of magnetite to reduce Cr(VI) in the nitrate media. X-ray absorption spectroscopy analysis supports the macroscopic evidence that more than 75 % of total Cr on the magnetite surfaces was adsorbed Cr(VI) species after 48 h.
KeywordsChromate Cr Groundwater Ions Magnetite Adsorption Surface Speciation Reduction Sulfate Nitrate X-ray absorption spectroscopy
Hexavalent chromium [Cr(VI) or chromate], has been recognized as one of the major toxic substances by the United States Environmental Protection Agency (USEPA) because of its carcinogenic effects . In a recent report by Environmental Working Group, [Cr(VI)] in tap water tested from 25 out of 35 American cities was greater than a proposed limit of 0.06 µg L−1 by the state of California EPA . While the occurrence of Cr in these water resources is contributed by anthropogenic (e.g., steel mills, leather-tanning facilities) and indigenous sources (weathering of rocks and soils), there is an imminent interest to reduce the concentration of Cr from drinking water resources.
Kendelewicz and other researchers postulated a two-step mechanism to explain the Cr(VI) sorption process: electrostatic attraction of Cr(VI) anions, followed by the electron transfer reaction between Cr(VI) and the structural Fe(II) to form Cr(III)(OH)3 [8, 12, 15, 16]. The Cr(VI) reduction mechanism was accompanied by simultaneous homogenous oxidation of Fe(II) released by passivation of magnetite . Especially at basic conditions, Fe(II) in magnetite is highly susceptible to auto-oxidation, resulting in a decrease in Cr(VI) reduction . Although the above sorption mechanisms were suggested, it is poorly understood how these steps are interfered by common ions in natural and waste waters. Our water resources usually contain ions like nitrate and sulfate that could potentially interfere with the formation of Cr(VI) precursor complex on the magnetite surface and or electron transfer reactions. This could potentially result in ineffective Cr(VI) immobilization with magnetite. Nitrate concentration in surface water ranges from 0.1 to 20 mg L−1, and it can be as high as 30 mg L−1 in wastewater . Sulfate in domestic sewage effluents can be as high as 500 mg L−1, and up to several thousand mg L−1 in some industrial effluents . It is possible that these anions can potentially interfere with Cr(VI) immobilization by magnetite via (1) competitive adsorption of nitrate and sulfate and (2) competitive electron transfer reactions.
In general, the strength of oxyanion complexation on metal oxyhydroxide surfaces can be predicted using the shared charge value (SCV), which is the positive oxyanion charge divided by the number of bonded O atoms. The lower the SCV, the stronger the affinity of oxyanion sorption. The SCV for NO3 − is 1.67 while SO4 2− and CrO4 2− both have a SCV of 1.5, indicating that the latter oxyanions have a slightly stronger metal-oxyanion ionic bond. Based on the SCV, one can expect that nitrate will not strongly perturb the initial CrO4 2− adsorption step. However, sulfate could compete for sorption sites, resulting in less chromate sorption and or suppression of electron transfer reactions.
The objective of this study was to investigate the effects of nitrate and sulfate on Cr(VI) removal by magnetite, as a function of pH and ionic strength (0.01 vs. 0.1) through batch sorption experiments. As reviewed above, numerous investigations in the same system [i.e., Cr(VI) in magnetite] were dedicated to the characterization of reaction products in corroded magnetite. This study, instead, focuses on the macroscopic behavior of the Cr(VI) removal process by magnetite in two different electrolyte systems. To understand the effect of these electrolytes on the Cr surface species, in situ Cr K-edge X-ray absorption spectroscopy (XAS) measurements were also conducted. These analyses allow for a greater understanding of the Cr(VI) removal capacity of magnetite in natural water systems.
Results and discussion
PZSE of magnetite
The PZSE of magnetite used in this study was determined using batch titrations with 0.01, 0.05 and 0.1 M NaNO3, and was approximately 5.63, slightly lower than reported PZSE and PZC values of synthetic magnetite, 6.3–6.8 [12, 19, 20]. Salazar-Camacho and co-workers also reported the isoelectric point (IEP) of two nano-magnetite samples to be 6.2 for <5 µm and 6.7 for <50 nm particles . This discrepancy may be due to surface oxidation and or impurities [22, 23, 24]. In the literature, comparatively lower PZSE values have been reported with natural magnetite samples [21, 25, 26].
Pseudo-equilibrium sorption experiments
Effects of pH
In both electrolytes, chromate sorption is pH dependent. The sorption generally increases with decreasing pH from 10 to 4 although a few data points at pH <5 (Fig. 1b) are influenced by the dissolution of solids. Similar pH dependent chromate sorption behavior has been documented in several studies [4, 5, 6, 12, 27, 28]. Assuming that Cr(VI) is present, the sorption trend can be explained by the aqueous speciation of chromate and the surface charge density of magnetite at given pH values.
At pH <5 (below PZSE of magnetite), surfaces of magnetite are positively charged. Chromate anions are expected to be strongly attracted to the surfaces via electrostatic interactions. This supports a 1st step to form the precursor complex prior to the electron transfer reaction suggested by Kendelewicz and co-workers [8, 15].
At pH >5, more negatively charged surfaces will be developed, further reducing the attraction of anions, like chromate. However, some sorption occurred at pH 8–11, possibly suggesting inner-sphere sorption mechanisms via ligand exchange reactions.
Effects of ionic strength
Although there are some variable data points in each electrolyte experiment (Fig. 1a, b), one can clearly see two distinct ionic strength effects on CrO4 2− sorption. In the sulfate media, Cr(VI) uptake was affected by changes in ionic strength. The sorption drastically decreased when ionic strength was increased from 0.0016 to 0.016 M sulfate at pH 3–12. Average Cr(VI) removal is 10.4 % lower at higher sulfate concentration. White and Peterson also previously reported the effects of SO4 2− concentrations (0.01–0.1 M) on chromate sorption . On the other hand, little effect of ionic strength effect was observed in the nitrate media. This observation is consistent with other studies that found negligible effects of NO3 − concentration on Cr(VI) removal by magnetite .
Hayes and co-workers previously proposed an indirect macroscopic method for distinguishing inner-sphere from outer-sphere complexes by examining ionic strength effects of inert electrolytes on oxyanion sorption envelopes coupled with the generalized triple layer model . Accordingly, inner-sphere complexes are not greatly affected by ionic strength, whereas the presence of outer-sphere complexes is indicated by a shift in the pH with changing ionic strength due to competitive sorption with counter anions. Based on the theory, one can suggest that chromate predominantly forms inner-sphere complexes in the NaNO3 media at pH 4–11, whereas chromate could adsorb to magnetite as a mixture of inner- and outer-sphere complexes in the Na2SO4 media. In the high ionic strength of Na2SO4, it is possible that the surface speciation of chromate is predominantly inner-sphere complexes at pH 6–12. These interpretations of sorption mechanisms, however, are contradicted in two different background electrolyte media, which is likely attributed to differences in inertness between nitrate and sulfate ions and or redox reaction at the surfaces. The macroscopic observation is useful in evaluating chromate removal from aqueous solution under different reaction conditions. However, the removal of Cr(VI) from solution should not be interpreted as the chemi-sorption of Cr(VI) anions in magnetite without any spectroscopic evidence. In the XAS analysis section below, chemical speciation of Cr on magnetite surfaces is discussed.
Effects of sulfate and nitrate
When the total Cr retention was compared in these electrolyte systems (Fig. 1), the sulfate system yielded more Cr retention by magnetite. Based on the SCV argument discussed above, sulfate should have interfered with the adsorption of CrO4 2−. However, this is not the case. The nitrate system yielded less Cr retention. It is likely that a different factor was involved in the reactions (Fig. 1). As reported by several previous studies [4, 5, 6, 7], Cr(VI) uptake by magnetite is attributed to the reduction of Cr(VI) by Fe(II) in magnetite. If the surface bound Fe(II) and the Fe(II) in crystal defects are consumed by other anions like nitrate, the presence of nitrate should lower the reduction of Cr(VI), resulting in less Cr uptake by magnetite. When ΔGo of oxyanion reduction was estimated using the half reaction Eqs. 3 and 6–9, Cr(VI) reduction is most favorable (ΔGo = −56.25 kJ), followed by nitrate reduction to nitrite (ΔGo = −11.57 kJ), nitrate reduction to ammonium (ΔGo = −10.13 kJ), and sulfate reduction to bisulfide (ΔGo = 385.17 kJ). This clearly suggests that sulfate reduction does not favorably occur at the standard state. However, nitrate could competitively oxidize surface available Fe(II) in magnetite. Although kinetics of competitive chromate and nitrate reduction was not measured in this research, it is clear that nitrate was more competitively oxidizing Fe(II) than sulfate, possibly resulting in less Cr retention in the nitrate system.
To better assess the macroscopic observation discussed above, the chemical speciation of Cr on the magnetite surface was investigated using XAS. Effects of ionic strength, pH and kinetics on the Cr surface speciation are discussed below.
Effect of ionic strength on Cr surface speciation
In the sulfate media (Fig. 4a, b), the amount of Cr(VI) on the magnetite surface was dependent on ionic strength under respective pH values. At basic pH values, low (0.0016 M) sulfate facilitated a very small amount of Cr(VI) (~0.1 %) on the surface [i.e., ~100 % of surface Cr is Cr(III)]. Cr(III)(OH)3(s) surface species are likely dominant at alkaline conditions. At acidic pH values, low sulfate yielded a large amount of Cr(VI) (60.4 %). Chromate was strongly adsorbed on Fe octahedral sites of the magnetite structure. As previously discussed, the shared charge value of sulfate (1.5) is smaller than that of nitrate (1.67), suggesting the greater affinity of sulfate on metal oxide surfaces. Its strong sorption mechanism has been well documented in different iron oxyhydroxide minerals. In goethite, CrO4 2− sorption occurs via inner-sphere complexation at near neutral pH values [33, 34, 35, 36]. The potential for any background oxyanion to force the formation of a Cr(VI) inner-sphere surface complex could also facilitate the reduction of Cr(VI) at the magnetite surface. Considering the positively charged magnetite surfaces at acidic pH, chromate anions should be strongly attracted. However, high (0.016 M) sulfate at acidic pH resulted in low Cr(VI) (1.7 ± 0.2 %) on the surface. Competitive sulfate adsorption in the high sulfate condition might be responsible for this pH dependent Cr removal from solution (Fig. 1).
In the nitrate media (Fig. 4c, d), there was a similar ionic strength dependency in the Cr(VI) surface speciation. At acidic pH, the fraction of Cr(VI) increased from ~16 to 91.4 % with decreasing ionic strength. High [nitrate] possibly competes with the chromate anion, resulting in less Cr(VI) sorption under the high nitrate condition. At basic pH values, there was an opposite trend. Surface Cr(VI) increased from ~6.1 to ~30 % with increasing ionic strength. At alkaline pH, total Cr removal was not strongly affected by changes in ionic strength. Therefore, the increase in the Cr(VI) fraction on the surface is not attributed to an increase in the quantity of Cr(VI) adsorption. The changes in the ratio of Cr(VI)/Cr(III) is likely due phase transformation at the surface. As discussed earlier, nitrate could oxidize Fe(II) as long as a substantial quantity of nitrate is present. However, low nitrate does not effectively oxidize Fe(II), leaving some reduction capacity of magnetite. This might be the reason why more Cr(III) remained on the magnetite surface.
Effects of pH on Cr surface speciation
When % Cr(VI) on the surface is compared at low and high pH values under the same ionic strength, there is a much larger difference in the two electrolyte systems at low pH values.
In the low sulfate media, % Cr(VI) increased from ~0.5 to ~60 % with decreasing pH (Fig. 4b). At acidic pH, pH dependent chromate adsorption was controlling the surface speciation at low sulfate concentration. It should be noted that, under acidic pH conditions, once reduction of the Cr(VI)O4 2− has occurred, Cr(III) cations might then be desorbed from the positively charged magnetite surface since it does not readily undergo a hydrolysis reaction to form Cr(III)(OH)3. This could account for the lower retention of Cr(III) on the surface at low pH values.
In the high sulfate media, % Cr(VI) increased from ~1 to ~22 % with increasing pH (Fig. 4b). At alkaline pH, auto oxidation of Fe(II) in magnetite is known to occur . Newly formed Fe(III) oxyhydroxide facilitates the adsorption of Cr(VI). For Cr(VI) anions to be adsorbed at basic pH, the Cr(VI) anion must undergo a ligand exchange reaction (i.e., inner-sphere) because of negatively charged mineral surfaces. For this reason, the effect of ionic strength of specific ligands (e.g., sulfate) on Cr(VI) adsorption occurs to a much lesser extent compared to those at low pH. This supports the macroscopic observation in Fig. 1a. Because of diminished ligand effects at high pH, the Cr(VI) sorption is more susceptible to changes in other physicochemical factors such as auto-oxidation and or the activity of OH−, which will induce the hydrolysis reaction of Cr(III).
In the nitrate medium, a similar pH effect is observed. However, the changes are even larger. In the low nitrate system, an incomplete reduction of Cr(VI) was observed. The amount of Cr(VI) retained was as high as ~80 % in the low nitrate media at low pH. The observation of incomplete reduction of Cr(VI) in low [NO3] agrees with previous reports [4, 37]. Since low nitrate does not compete for the chromate adsorption, chromate anions are readily adsorbed on the surface. In the high nitrate media, however, % Cr(VI) increased from ~15 to ~28 % with increasing pH (Fig. 4d). Similar to the high sulfate system, auto oxidation of Fe(II) in magnetite is expected at high pH. Newly formed Fe(III) oxyhydroxide facilitated the adsorption of Cr(VI).
Kinetic effects on Cr surface speciation
The % Cr(VI) fraction on the surface increases from 15 to 30 min, suggesting that Cr(VI) adsorption was still occurring at the surfaces. Shortly after 30 min, the amount of surface sorbed Cr(VI) decreases up to ~3 h. This suggests the reduction of Cr(VI) occurred. Interestingly, between 3 and 12 h, there was an increase in the Cr(VI) fraction to ~80 %. Our interpretation is as follows. Cr(VI) reduction occurred up to ~3 h, and then electron transfer reaction was suppressed due to the formation of Cr(III) hydroxide surface precipitates. While the formation of a Cr(III)(OH)3(s) passivation layer can be one of explanations for the inhibitory mechanism [8, 9, 10, 11], the transformation of adsorbent can also be pointed out at this low pH. During the Cr(VI) reduction, the depletion of Fe(II) from magnetite structure is simultaneously occurring. Both XRD and TEM analyses showed the transformation of magnetite to goethite and or maghemite (γ-Fe2O3) and then hematite (α-Fe2O3) under oxidized conditions . A structural polymorph of hematite is the most common weathering product of magnetite in oxic environments. The formation of a passivation layer can also be facilitated by sulfate promoted Fe(II) dissolution. Sulfate ions could also complex with Fe(II), and increase the dissolution of Fe(II) from the magnetite structure [7, 41]. Depending on the reaction pH, the dissolved Fe(II) can precipitate as Fe(OH)2, and eventually oxidize to form a ferrihydrite/goethite passivation layer.
EXAFS Analysis of steady state samples
Least square analysis of Cr K-edge XAS spectra
pH 4 (± 0.02)
pH 4 (± 0.02)
Based on the first shell analysis, it is clear that both Cr(VI)O4 and Cr(III)O6 surface species are present. Coordination number of Cr–Cr/Fe distance at 2.91 Å is about one. This corresponds to the edge sharing mononuclear Cr(VI)O4 on FeO6 in goethite . Edge sharing mononuclear Cr(III) on FeO6 in goethite can be also considered along with Cr(III) co-precipitates . A distance (2.98 Å), which is consistent with edge of two MeO6 polyhedral with Me as Fe and or Cr, was reported in the XAS analysis of Cr(III) surface precipitates (γ-CrOOH) in ferrihydrite at pH 4 . Feff/XRD generated Cr–Cr interatomic distance in bracewellite, CrO(OH), at 2.97 Å .
There is an additional Cr–Cr/Fe shell at ~3.5 Å in both samples. The similar distance was previously reported as multinuclear Cr surface species on the hematite (0001) surface via grazing incident-XAFS analysis . Double corner sharing of CrO6 to Cr/FeO6 yields in a similar distance . Feff/XRD simulation of bracewellite structure shows the Cr–Cr interatomic distance of ~3.4 Å. The Cr–Fe distance of 3.4 Å was reported in Cr(III) substituted α-FeOOH .
Magnetite readily removed dissolved Cr(VI) from solution in the presence of nitrate and sulfate. Like other oxyanions, sorption of Cr(VI) increases with decreasing pH. While the effects of ionic strength were more pronounced in sulfate media than nitrate media, total Cr retention was greater in sulfate solutions than in nitrate solutions. The oxidation of Fe(II) (as surface bound or crystal defects) in magnetite by nitrate suppressed Cr(VI) reduction, resulting in less Cr removal in nitrate media. In sulfate media, competitive adsorption of sulfate was more of an important factor at acidic pH. XANES analysis revealed that the Cr(VI) surface reduction occurred at high pH in low ionic strength (0.01 M) of both electrolytes. However, such electron transfer reactions were suppressed at low pH, resulting in more adsorbed Cr(VI) on the surfaces. Because of the structural alternation of adsorbent (i.e., formation of passivation layers such as Cr(III) precipitates and Fe(III) oxyhydroxides), the kinetics of Cr(VI) reduction was slow after 3 h as evident in the XANES and EXAFS analysis. Adsorbed Cr(VI) surface species dominated during the initial several hrs, and nearly 50 % of total Cr on the surface was adsorbed Cr(VI) anions in both sulfate and nitrate media. This suggests that adsorption processes of Cr(VI) anions on magnetite surfaces is as important as the reductive precipitation of Cr(III) in explaining the removal of Cr(VI) with magnetite. In assessing the stability of sorbed Cr in magnetite, it might be important to consider the desorption process of Cr(VI) anions with respect to common ions in natural waters.
Synthetic magnetite (Fe3O4) nanopowder was obtained from Nanostructured and Amorphous Materials, Inc. (Houston, TX) Particle size was 50–100 nm with >99 % purity. The following ACS grade chemicals were prepared in degassed ultrapure water (18.2 MΩ): sodium nitrate, sodium sulfate, nitric acid, sulfuric acid, and sodium hydroxide. Solutions of ACS grade sodium chromate tetrahydrate, sodium acetate, and 3-propanesulfonic acid (MOPSO) were prepared in 0.01 M and 0.1 M NaNO3 and 0.0016 M and 0.016 M Na2SO4. These concentrations represent 0.01 and 0.1 ionic strengths for the background solutions, respectively. Standards were prepared using the NIST traceable ICP-MS standard ammonium dichromate (1000 mg/L Cr in 3 % nitric acid, 99 %, Ricca Chemical Company). The ACS grade chemicals potassium chromate [Cr(VI)] and chromium oxide [Cr(III)] were used for the X-ray energy calibration.
Potentiometric acid–base titrations were conducted using 0.2 g/L magnetite nanopowder in 0.01, 0.05 and 0.1 M NaNO3 backgrounds. Solutions were prepared in individual 50 mL Nalgene polypropylene sterile high-performance (PS) centrifuge tubes. The nanopowder was hydrated for 24 h on an end-over-end shaker at 20 rpm; afterwards a predetermined amount of 0.01–0.1 M NaOH and HNO3 were added to each tube resulting in an approximate pH range of 3–10. The samples were then shaken on an end-over shaker for 24 h. The final pH values were plotted against total acid concentration and the point of intersection in the batch titration curves was used to find the point of zero salt effect (PZSE) .
Batch sorption experiments
Magnetite suspensions were prepared in 5 g/L solid to solution ratio in 50 mL PS high-performance centrifuge tubes. Samples were hydrated in 0.001, 0.1 M NaNO3, 0.0016 or 0.016 M Na2SO4 degassed background solutions for 10 h on an end-over-end shaker at 30 rpm. It is important to note that no magnetic stir bar was used due to the magnetic property of magnetite. pH values were adjusted before and after hydration using 0.01–1 M NaOH and either H2SO4 or HNO3 depending on the background electrolyte. Samples were prepared over an approximate pH range of 3–12; no buffer was used. The solutions were spiked with 0.5 mM Na2CrO4∙4H2O and returned to the shaker for 24 h. After the experiment the pH of each sample was recorded and aliquots were collected, filtered through a 0.2 µm polyvinylidene fluoride (PVDF) filter. Filtrates were diluted with 1 % Suprapur® nitric acid, and then analyzed using an inductively coupled plasma mass spectrometer (ICP-MS) Thermo Scientific X Series 2 that was calibrated using a Cr(VI) NIST traceable ICP-MS standard. The Cr(VI) was assured using a spectrophotometric method .
All XAS samples were prepared at room temperature. Kinetic samples were freshly prepared at the Stanford Synchrotron Radiation Laboratory (SSRL), Menlo Park, CA. For equilibrium samples, sorption samples were prepared at 10 g/L for collection and analysis purposes. The hydration, spiking, and aliquot collection procedure were identical to the sorption experiments. Kinetic samples for X-ray absorption near edge structure (XANES) analysis were prepared in 50 mL high-performance centrifuge tubes with 5 g/L solid to solution ratio with either 0.01 M NaNO3 or 0.016 M Na2SO4 and acidic pH (4.01 ± 0.10). Acidic pH was chosen because of this reaction condition provides sufficient Cr loading level for rapid (i.e., single scan) XANES measurements. Sodium acetate (50 mM) was used as a buffer solution. Tubes were placed on an end-over-end shaker at 30 rpm and one tube was sacrificed for each time interval. Mineral suspensions were spiked with 1 mM Na2CrO4∙4H2O and sampled at 15, 25, 40 min, and 1, 3, 12 h. Each sample was filtered using vacuum filtration on PVDF filter papers, trapped between Kapton tape, and immediately analyzed at the beamtime. We chose the room temperature analysis with one scan over the cryo measurements since the sample loading time in a cryo cell and holder requires more than 5 min. For the extended X-ray absorption fine structure spectroscopy (EXAFS) measurement, equilibrium samples after 48 h were used.
All samples were analyzed at beam line 4–3 at SSRL. The electron storage ring was operated at 3 Ge V energy with a current range of 80–100 mA. The energy calibration was performed at 5989 e V using the first derivative of a Cr foil XANES spectrum. Fluorescence-yield Cr K-edge spectra were collected using a 4 element vortex detector. The monochromator was a Si(111) double-crystal with a non-fixed exit slit. Sample holders were oriented at 45° to the unfocused incident beam. All samples were run at room temperature.
To assess the change in Cr valence state at the mineral–water interface during the sorption reaction, a Cr pre-edge peak standard curve was constructed using the Cr K-edge pre-edge peak of Cr(VI)/Cr(III) mixtures. All reference spectra were collected in transmission mode. The reference salts, K2Cr(VI)O4 and Cr2(III)O3, were mixed to give a range (0–100 %) of Cr(VI) concentration, ground with a diamonite mortar and pestle, and the fine powder was trapped in Kapton tape.
The data reduction of bulk XANES spectra was performed using the SixPACK/IFEFFIT interface . Because of fast sorption reactions, only one spectrum was collected per kinetic sample. The following data normalization was carried out at approximately 5800–6150 eV. A Gaussian function was used for normalization of the pre-edge region and a quadratic function was used for the post-edge region. Extended X-ray absorption fine structure spectroscopy analysis was conducted in two equilibrium sorption samples after 42 h according to the method described in Arai and Livi . Only two spectra were averaged and splined up to 11.1 Å−1. Because of only two scans, any noise in Fourier transformed radial structural function (RSF) feature >3.6 Å was unable to be fit. The structural refinement data of chromite and K2CrO4 were used to generate single scattering paths for Cr(III)–O, Cr(VI)–O, Cr(III)–O and Cr–Fe [50, 51]. In order to assess the fraction of Cr(III) and Cr(VI), a sum of each fraction was set to unity, and each fraction was multiply to CN of each Cr path. Based on tetrahedral structure of Cr(VI) and octahedral structure of Cr(III), CN was fixed at 4 and 6, respectively. The rest of fitting parameters were floated unless otherwise mentioned in the text.
AHM conducted batch experiments and characterization of magnetite. AHM and YA both collected the XAS data and process the data for the XANES analysis. YA was responsible for EXAFS analysis of Cr reacted magnetite. The MS was contributed by both authors. All authors read and approved the final manuscript.
This research was supported by the NIFA hatch fund (1-600116-875000-875939) and the South Carolina Universities Research and Education Foundation, Contract No. DE-AC09-08SR22470. Portions of this work were performed at BL4-3 at SSRL. These facilities are supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515.
The authors declare they have no competing interests.
- 1.U.S. Environmental Protection Agency (EPA) Toxicological review of hexavalent chromium. National Center for Environmental Assessment, Office of Research and Development, Washington. (1998)Google Scholar
- 2.National Toxicology Program (NTP) NTP technical report on the toxicology and carcinogenesis studies of sodium dichromate dihydrate (CAS No. 7789-12-0) in F344/N rats and B6C3F1 mice (Drinking water studies). NTP TR 546, NIH Publication No. 07-5887: National Toxicology Program, National Institutes of Health, U.S. Department of Health and Human Services (2008). http://ntp.niehs.nih.gov/files/546_web_FINAL.pdf
- 3.Office of Environmental Health Hazard Assessment (OEHHA) Draft Public Health Goal for Hexavalent Chromium in Drinking Water: Pesticide and Environmental Toxicology Branch, Office of Environmental Health Hazard Assessment, California Environmental Protection Agency (2009).ss www.oehha.ca.gov/water/phg/pdf/Cr6PHGdraft082009.pdf
- 4.He Y (2003) Chromate reduction and immobilization under high pH and high ionic strength. Ph.D. Dissertation, Ohio State UniversityGoogle Scholar
- 13.Bard AJ, Parsons R, Jordan J (1985) Standard potentials in aqueous solution. Marcel Dekker Inc, New York, p 6Google Scholar
- 14.Walther JV (2009) Essentials of Geochemistry. Jones & Bartlett Learning; 2 edition. Sudbury, MAGoogle Scholar
- 17.Nollet LML, De Gelder LSP (2000) Handbook of water analysis. CRC Press, Marcel Dekker, Inc., New York, p 201Google Scholar
- 24.Tombácz E, Illés E, Majzik A, Hajdú A, Rideg N, Szekeres M (2007) Aging in the inorganic nanoworld: example of magnetite nanoparticles in aqueous medium. Croat Chem Acta 80:503–515Google Scholar
- 29.Gustafsson JP (2007) Visual MINTEQ. Visual Minteq. Version 3.0. Division of land and water resources, Royal Institute of Technology. Stockholm. http://www.lwr.kth.se/English/OurSoftware/vminteq/index.htm
- 30.Washburn EW, West CJ (1929) International critical tables of numerical data, physics, chemistry and technology; National Academies.7Google Scholar
- 37.Chambers S, Brown, Jr. GE, Amonette J, Dixon D, Joyce S, Rustad J (1997) Molecular-level processes governing the interaction of contaminants with iron and manganese oxides. Pacific Northwest National Laboratory. 67Chambers S, Brown, Jr. GE, Amonette J, Dixon D, Joyce S, Rustad J (1997) Molecular-level processes governing the interaction of contaminants with iron and manganese oxides. Pacific Northwest National Laboratory. 67Google Scholar
- 44.Milton C, Appleman DE, Appleman MH, Chao ECT, Cuttitta F, Dinnin JI, Dwornik EJ, Ingramand BL, Rose BL, Jr Ingramand HJ (1976) Merumite, a complex assemblage of chromium minerals from Guyana. US Geol Suns Prof Pap 887:1–29Google Scholar
- 48.Webb S (2005) SIXpack: A graphical user interface for XAS analysis using IFEFFIT. Physica Scripta 1011Google Scholar
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. | <urn:uuid:a4a69162-a3e9-436f-9bd0-beec5e441492> | 2.78125 | 7,708 | Academic Writing | Science & Tech. | 51.674658 | 95,558,502 |
General debugging steps
- Configure the debugger options
- Choose the desired CMake profile.
- Define a run/debug configuration for the application to be debugged.
- Create breakpoints in the source code.
- Launch a debugging session.
- Pause or resume the debugging session as required.
- During the debugger session, step through the breakpoints, evaluate expressions, change values on-the-fly examine suspended program, set watches and watchpoints.
After you've started a debug session, the icon that marks the Debug tool window toggles to to indicate that the debug process is active.
After you have configured a run configuration for your project, you can launch it in debug mode by pressing Shift+F9.
In the Debug tool window you can see the list of frames and threads with their states, variables and watches. When you select a frame, you see the variables corresponding to the selected frame.
Useful debugger shortcuts
Breakpoint details and condition
If you want to change details of a breakpoint, press Ctrl+Shift+F8. Here you can specify the breakpoint conditions.
If you have any instance marked with a label, you can use it in the condition expression as well:
To see all breakpoints in the project (with more advanced settings), press the same shortcut Ctrl+Shift+F8 again.
Another action might be useful if you want to evaluate something at a particular line of code without actually making a stop. You can do that by using the Action breakpoint. To create one, just click on the gutter while holding Shift.
To create a breakpoint that stops only once, click the left gutter while holding Shift+Alt.
Refer to the section Using Breakpoints for details.
It's also useful to know that any breakpoint can be quickly disabled by clicking on the gutter while holding Alt.
Refer to the section Enabling, Disabling and Removing Breakpoints for details.
In case you want to “go back in time” while debugging you can do it via Drop Frame action. This is a great help if you mistakenly stepped too far. This will not revert the global state of your application but at least will get you back by stack of frames.
The icon is described in the Debug tool window reference.
Run to cursor
Sometimes you need to resume the program and stop at another line of code, without adding another breakpoint. Easy: just press Alt+F9.
The icon is described in the toolbar reference of the Debug tool window.
The next time this instance appears in Watches, Variables or Evaluate expression, you will see the label:
While in debug mode, you can evaluate any expression by pressing Alt+F8.
This tool provides code completion just as in the editor so it’s very easy to enter any expression:
If you have any instances marked with labels, code completion will offer you its names so you can evaluate them:
Refer to the section Evaluating Expressions for details.
The final thing you definitely should know about debugging in CLion is Remote debug. Remote debug means attaching debugger to a process which is already running on a specific port on your or any other’s host. This way you can attach the debugger to your application server which is running standalone.
To create a remote configuration, go to Edit configurations and add Remote run configuration. Make sure to specify the correct host and port before you run this configuration.
If you want to change the default debugger settings, choose Debugger in CLion Settings/Preferences. | <urn:uuid:1361a494-8b43-46cd-ab61-095dadd20aad> | 2.609375 | 740 | Tutorial | Software Dev. | 49.121789 | 95,558,504 |
Derivation of the Momentum Transport Equations
In the analysis of fluid flow problems, the equation of continuity (material balance) is usually the initial principle invoked. The information gleaned from the equation of continuity is then applied to the equation of motion. From the equation of motion and the fluid properties, the velocity profiles, average velocities, and energy loss can be calculated.
KeywordsShear Rate Newtonian Fluid Viscous Term Momentum Transport Shear Stress Component
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- Transport Phenomena, by R. B. Bird, W. E. Stewart, and E. N. Lightfoot, John Wiley, New York, 1960.Google Scholar
- Process Analysis and Simulation, by D. M. Himmelblau and K. B. Bischoff, John Wiley, New York, 1968.Google Scholar
- Low Reynolds Number Hydrodynamics, by J. Happel and H. Brenner, Prentice-Hall, Englewood Cliffs, N. J., 1965.Google Scholar | <urn:uuid:0cc0138e-0010-46db-9775-f3be24f35e1d> | 2.8125 | 223 | Truncated | Science & Tech. | 54.162493 | 95,558,514 |
A team of Indian astrophysicists is searching for signals from the first stars and galaxies that can answer many questions about the ‘dark ages’ proceeding the Big Bang.
The 12-member team of researchers from Raman Research Institute (RRI), Bengaluru, is using an indigenous radio telescope and other instruments in its attempt to trace these signals.
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Image for representation only. Source: by By ESO/B. Tafreshi, via Wikimedia Commons
The team has claimed that it will soon be possible to detect such signals, based on the first round of observations from a place located 4,800 metres above sea level, in Ladakh. According to a report by The Times of India, it is the highest night sky observation point in the world.
The project is named SARAS (Shaped Antenna measurement of the background Radio Spectrum). It consists of an antenna connected with analogue as well as digital receivers that capture data from the sky and record it for further analysis. The team aspires to detect the signals emitted when the first stars and galaxies were formed. It is believed that these signals, known as the 21-cm signals, hold the key to many unanswered questions.
Being emitted an entire epoch ago, the signals are extremely weak to catch. They are believed to have been emitted when the universe was only 250-550 million years old. (It is now 13.7 billion years old.)
“The frequency range one needs to look for the signal is between 40 MHz and 200 MHz. Contaminations can be a million times stronger than the signal. Hence, it comes as no surprise that after more than a decade of international efforts, the signal has not yet been detected…After acquiring data for four nights in the Ladakh region, we are analysing it. The primary results are encouraging and we are achieving amazing levels in sensitivity. This has boosted our confidence that detection of the signal may not be too far,” team member Saurabh Singh told TOI.
The signal data will be shared with Prof Rennan Barkana, an expert from Tel Aviv, Israel.
What were the dark ages?
It took approximately 400,000 years after the Big Bang for the universe to cool down enough for ions to recombine into atoms and create light. This period is referred to as the ‘dark ages’. The signals that were emitted from the stars and galaxies in this period are precious to expand our understanding of the dark ages.
Scientists have been trying to trace these signals for many years now. A telescope project titled Square Kilometre Array (SKA) has been initiated by ten nations including India, with the same purpose. The telescope once completed will be the world’s largest and most sensitive radio telescope. | <urn:uuid:c7acfe33-95e8-4f97-891f-a75d99598c6d> | 2.984375 | 721 | News Article | Science & Tech. | 45.633727 | 95,558,519 |
Recent Development of Gas–Solid Phase Chemiluminescence
Serving as a classic and interesting strategy, gas–solid phase chemiluminescence (CL) has recently been a rapidly growing area where CL is emitted through chemical reactions between gas and solid reactants occurred on the surface of solid matter. This CL system provided a sensitive and simple spectral method for investigating gas–solid phase reactions while information on the rate constants, intermediate productions, surface states and reaction mechanisms of interaction could be acquired. Recent progresses mainly concentrate on development of new gas–solid phase CL systems and their practical applications. This review paper summarized main classifications, mechanisms and applications of gas–solid phase CL. The future prospects for gas–solid phase CL are discussed.
KeywordsGas–solid phase chemiluminescence Recent development Main classifications Mechanisms Applications
Chemiluminescence (CL) is the light emitted during chemical reactions where unstable products are evolved in the reaction process. These intermediates transformed from electronically excited to ground state with CL emission as energy release (> 45 cal/mol) . Since the fireflies and other luminescent organisms in the environment have been found, CL has aroused considerable interest for deeper research and application . Definitely, CL analysis has excellent advantages including high sensitivity, low background interference, highly responsive signals, safe operation process and portable equipment , which has been applied to detection towards the concentration of catalyst, reactant, CL inhibitor and enhancer . A great many articles have reported the applications of CL in environmental analysis , medical diagnosis , health management , food safety and pharmaceuticals , etc.
Among numerous branches of CL systems, acting as a classic and interesting strategy, gas–solid phase CL has recently been a rapidly growing area. Such CL evolves in infrared, visible, and even in ultraviolet regions through chemical reactions between gas and solid reactants on the surface of solid matter. It acts as an indicator and monitor of gas–solid phase reactions to provide information during the process of reaction . Moreover, this strategy also enables investigations of gas–solid phase reactions through sensitive and simple spectral method . In addition, application of gas–solid phase CL has extended to gas-phase and solid-phase diagnose and detection due to its strong intensity of signals and unique property. Over decades of years of investigation and development, gas–solid phase CL has become an effective detection method in analytical chemistry. Recent progress mainly focuses on development of new gas–solid phase CL systems and their practical applications, while many interesting results have been reported. Obviously, the excellent sensitivity and intensity of gas–solid phase CL has made it a good candidate as a novel CL technology, which has revealed great potential for future analysis and test.
Considering the aforementioned properties, gas–solid phase CL have received considerable attentions in different areas of CL analysis. The present paper introduces the main classifications including O3-solid, O2-solid, “S-based”-solid, H2-solid and CO-solid CL systems. Besides, specific mechanisms, applications and future prospects of gas–solid phase CL are also covered.
2 Main Classifications of Gas–Solid Phase CL
2.1 O3-Solid System
2.1.1 O3–Ba System
2.1.2 O3–Ca System
2.1.3 O3-Alcohols, Phenols and Saccharides System
2.2 O2-Solid System
2.2.1 O2–Na System
O2 has always played as an effective oxidant towards all kinds of solid reactants for so many years. Researchers found that freshly cut Na would emit faint green light, which opens a new area of luminescence by Na metal. In 1931, Bowie has investigated the color and intensity of CL emitted by solid Na existed in the air. He found that relevant intensity ranged from 3.5 to 10.5 × 10−7 lumens per square inch of the surface of Na and the CL spectrum was composed of a band of 5000–5300 Å. The CL intensity was too much low and corresponding color was green. He also investigated the mechanism within this process and believed that the CL has close relationship with formation of hydroxide from the moisture in the air where the breaking of H–O bond within a vaporous and polar molecule played as the main role .
2.2.2 O2-Fuel System
Investigation towards reactions of fuel will definitely acquire the information on ballistic property, which in return guides further modification and development. Campbell and Hulsizer obtained the CL spectra of ammonium perchlorate composite solid propellant burned in the combustion zone. They found that A 2Σ+ electronic state of OH· was evolved in the flame, while these short-lived OH· also exist in the place very far from the surface of propellant. This system facilitated investigating the internal energy levels of ground and excited state during the process of combustion occurred at the surface of solid propellant.
2.2.3 O2-Polymer System
Research towards oxidation of polymer via CL strategy has enabled evaluation of oxidation mechanism, rate constant and further application of such process. Zlatkevich utilized CL method for discussing heterogeneous oxidation of polypropylene. This work pointed out the erroneous evaluation of the activation energies and interpretation by previous articles. He also believed that experimental support is inadequate while the evolution of volatiles in the induction process also lacked sufficient consideration.
2.3 “S-Based” Solid System
2.3.1 S2-Solid Ar System
Kiljunen et al. also investigated electronic structure and short-range recombination dynamics of S2 in solid Ar by classical molecular dynamics simulations. Result showed that S atom separated by closest distance of the lattice would recombine immediately even at 1 K with excitation energies of 2 eV or more to give excited S2.
2.3.2 SO-Solid Ar System
2.3.3 SO2-Solid Y2O2S–Eu System
2.4 H2-Solid System
2.4.1 H2-Solid Zn2SiO4–Mn System
2.4.2 H2-Solid ZnSCdS-Cu System
2.4.3 H2-Solid SiC System
2.5 CO-Solid System
3 Mechanisms of gas–solid phase CL
4 Applications of Gas–Solid Phase CL
A variety of equipment has been realized for detection and analysis of specific atoms or radicals based on gas–solid phase CL occurred at the surface of solid reactant, which laid foundation for obtaining information about rate constant, intermediate production, surface state and reaction mechanism of a CL system. What is more, this strategy could also be utilized in realistic determination to acquire real-time results of samples.
4.1 Chemical Sensor
A novel gas–solid phase chemical sensor based on CL strategy was devised by Karpov et al. . Serving as an effective complementary facility for traditional analytical techniques, this sensor has been applied to measurement towards the concentration of H, O and other gaseous chemical radicals. With the CL induced by Eley–Rideal recombination process took place, relevant property of such sensor has reached the sensitivity of 105 cm−3 with test time about 1 s.
4.2 CL Imaging
4.3 CL Spectrometer
Pronko and Chapman have developed a microcomputer-controlled CL spectrometer with effective response and low cost, which could be utilized to study CL effect on the surface of materials in certain atmosphere. In addition, the CL spectra as a function of time and temperature could be recorded completely automatically. With the control of microcomputer, CL spectra in different regions could also be obtained.
5 Conclusions and Future Prospects
In this review article, we mainly concentrated on recent development of gas–solid phase CL. The main classifications including O3-solid, O2-solid, “S-based”-solid, H2-solid and CO-solid CL systems are summarized. In addition, specific mechanisms and applications of gas–solid phase CL in chemical sensor, imaging and spectrometer are also concluded. Results demonstrate that gas–solid phase CL system acts as a novel and effective platform for detection and analysis.
The investigation on gas–solid phase CL will create a new area by analyzing chemical reactions through gas–solid phase CL performance thus the information on rate constants, intermediate productions, surface states and reaction mechanisms could be acquired.
Moreover, gas–solid phase CL has provided a novel alternative in determining the concentration of gaseous atoms or radicals (H, O, S, etc.) which is complicated through traditional analytical methods. The unique characteristics of gas–solid phase CL like high sensitivity and strong CL intensity have made it an excellent tool in probing the emissive property of solid reactant in certain atmosphere.
Notably, gas–solid phase CL also eliminated the interference from solution where impurity and other reactants would inevitably influence the detection procedure and later deduction of mechanism. Serving as a simple CL process, gas–solid phase interaction facilitates fast identification and verification in real samples.
Although gas–solid phase CL also suffers from incomplete transformation due to surface reaction where most reactants in the bulk stay unreacted, the endeavor of establishment of new CL system and application in sample analysis will be invaluable to make contribution to further development of gas–solid phase CL system. With new achievement and challenges appearing continuously, research towards gas–solid phase CL remains a hot theme.
This work was supported by the National Natural Science Foundation of China (Nos. 21227006, 21435002, 81373373, 21621003). The authors declare no competing financial interests. All authors have given approval to the final version of the manuscript.
- 33.Simpson TB, Bloembergen N. Infrared multiphoton dissociation of SO2. Mass Spectrom Rev. 1984;28:390–424.Google Scholar
- 34.Grankin VP, Grankina ND, Klimov YV, Tyurin YI. A study of recombination of hydrogen atoms on the surface of solids by the chemiluminescence method. Russ J Phys Chem. 1996;70:1729–34.Google Scholar
- 37.Tyurin YA, Styrov VV, Khoruzhii VD, Gorbachev AF, editors. Heterogeneous chemiluminescence (GHL) of the ZnSCdS-Cu and phosphors activated by Re ions. In: Russian–Korean International Symposium on Science and Technology, vol. 1. 2001. p. 331–4.Google Scholar
- 38.Sivov YA, Tyurin YI, Choruzhii VD. Electron-hole pairs multiquantum generation mechanism in the process of excitation of ZnSCdS-Cu by an atomic hydrogen. Physics. 2000;5:1–5.Google Scholar | <urn:uuid:95877f8e-cddd-424d-b369-6f1792485613> | 2.703125 | 2,272 | Academic Writing | Science & Tech. | 38.185389 | 95,558,539 |
Heinrich Rudolf Hertz is a German physicist who invented the delivery of electrical energy from 2 point (point) without wires (wireless). His most recent invention is the electric charge jump. He was born on February 22, 1857 and passed away on January 1, 1894.
Hertz sued his education at the Institut University of Kiel, University of Karlsruhe, University of Bonn. His university at the University of Munich, University of Berlin. He is a Doctoral Counselor from Hermann von Helmholtz . He is also known for his discoveries on Electromagnetic Radiation and Photoelectric Effects.
Heinrich Rudolf Hertz is regarded as the most meritorious figure in the field of Electromagnetism, the branch of physics about the electromagnetic field studying the electric field and magnetic field. The electric field can be produced by static electricity charges, and can give rise to electrical force. The magnetic field can be produced by the movement of electrical charges, such as the electric current flowing along the wire and giving rise to magnetic force.
Heinrich Rudolf Hertz
Born: February 22, 1857 Hamburg
Died: January 1, 1894 (age 36)
Place of residence: Germany
Fields: Physics, Electronics
Institution: University of Kiel,
University of Karlsruhe, University of Bonn
Alma mater: University of Munich,
University of Berlin
Hermann von Helmholtz
Known for: Electromagnetic Radiation,
The term "electromagnetism" comes from the fact that electric fields and magnetic fields are mutually "twisted" / related, and in many ways, it is impossible to separate them. For example, a change in the magnetic field can provide an increase to the electric field; which is a phenomenon of electromagnetic induction, and is the basis of the operation of electric generators, induction motors, and transformers.
The term electrodynamics is sometimes used to refer to a combination of electromagnetism with mechanics. This subject deals with the effects of electromagnetic fields in the mechanical properties of electrically charged particles.
To appreciate the services of Heinrich Rudolf Hertz for his contribution in the field of electromagnetism his name is enshrined in units of hertz frequency, Hertz is the SI unit for frequencies denoting the number of waves in one second (1 Hertz = 1 wave per second). This unit can be used to measure any periodic wave. Example: The frequency of clock wall motion is 1 Hz. | <urn:uuid:b2f98e93-770a-4475-ae80-6e1978ac97da> | 3.34375 | 528 | Knowledge Article | Science & Tech. | 24.805535 | 95,558,602 |
Please see the attached file for the fully formatted problems.
1. When performing a Friedel-Crafts alkylation reaction, not only does one have the problems
of multiple alkylation and rearrangement of the cation, but the presence of strong electron
donating groups prevents reaction. Provide an explanation for this.
2. Metallocenes, like ferrocene cannot be nitrated. Why?
3. Draw the structure of the diacetylferrocene you would obtain if ferrocene were diacetylated.
4. Draw an arrow pushing mechanism for the formation of the acylium ion when acetic
anhydride reacts with phosphoric acid.
5. Provide the major organic product(s) for the following reactions.© BrainMass Inc. brainmass.com July 17, 2018, 3:38 pm ad1c9bdddf
Friedel-Crafts alkylation and acylation and nitration of ferrocene and acetylferrocene are discussed in detail. | <urn:uuid:613e1b7e-8434-4b06-92f3-275c5682930d> | 2.890625 | 218 | Tutorial | Science & Tech. | 42.23513 | 95,558,613 |
Armchair astronomers using the galaxyzoo.org Web site have identified more than 500 overlapping galaxies in the local Universe when astronomers had previously only known of 20 such systems.
“This is the best Christmas present our users could hope for!” said Dr. Chris Lintott of Oxford University, a member of the galaxyzoo.org team. “Overlapping galaxies are useful because they enable us to study the dust in each system. Dust grains play a crucial role in the evolution of galaxies and how we see them - the presence of such dust is critical for star formation.”
Visitors to www.galaxyzoo.org get to see stunning images of galaxies. By classifying some of these images, visitors are helping astronomers to understand the structure of the universe. The new digital images were taken using the robotic Sloan Digital Sky Survey telescope in New Mexico.
Each of the 500+ overlapping galaxies was discovered by a member of the public signed up to the galaxyzoo.org forum where armchair astronomers can compare notes on the images of galaxies they have seen and classified using the website. The search for overlapping galaxies was led by Dr. William Keel, professor of astronomy at The University of Alabama. Keel wrote on the forum asking people to look out for suitable systems.
“The thousands of GalaxyZoo users have now found almost 700 such pairs, going much deeper into space than our earlier searches,” Keel said. “With so many to select from, we can now examine how the dust content of galaxies changes with the galaxy's type and brightness. This work should lead to comparison with incoming Hubble data on galaxies in the early Universe, so we can trace the history of cosmic dust with a single technique. This matters because so much starbirth is dust-shrouded, making it crucial to understand how to compensate for this in our calculations.”
Astronomers have been awarded five night’s use of the WIYN telescope on Kitt Peak, Arizona, to take a closer look at the overlapping galaxies identified by the Galaxy Zoo volunteers. The WIYN telescope is one of the largest in the Northern hemisphere and one of the most advanced in the world. This work will begin on April 25.
“We are expecting to get some spectacular images from our Arizona nights but, with the first set of science papers on Galaxy Zoo coming out very soon, we still need more volunteers to visit galaxyzoo.org,” said Lintott. “Even if you’ve visited the site before, please come back and classify some more galaxies in between mouthfuls of turkey and Christmas pudding as we need your help to confirm our results, results which could have a profound impact on our models of the universe.”
The Galaxy Zoo team includes scientists from the University of Oxford, the University of Portsmouth, Johns Hopkins University, and Fingerprint Digital Media of Belfast. Galaxyzoo.org has more than 110,000 users who have viewed more than 30 million images between them. The work on overlapping galaxies has involved the Galaxy Zoo team and astronomers from UA and the Space Telescope Science Institute in Baltimore.
A spectacular Hubble image of an overlapping galaxy, NGC3314, can be viewed at tinyurl.com/2poab5 .
Source: University of Alabama
Explore further: Team aims to use new NASA telescope to capture light from the first stars to be born in the universe | <urn:uuid:38b01cae-1015-4414-b87d-5e07eff6fdc6> | 3.171875 | 705 | News Article | Science & Tech. | 43.055414 | 95,558,614 |
Write smallest three-digit number, which in division 5 and 7 gives the rest 2.
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Plumber had to cut the metal strip with dimensions 380 cm and 60 cm to the largest squares so that no waste. Calculate the length of the sides of a square. How many squares cut it? | <urn:uuid:8cf9ddee-5575-4b4b-a150-4ade1c17ab91> | 3.53125 | 728 | Content Listing | Science & Tech. | 79.011636 | 95,558,619 |
Hummingbirds arent known for their power-lifting prowess. But researchers nevertheless put nearly 1,000 Peruvian hummers through lifting trials and flight tests over a two-year stretch in order to find out how their flying abilities are affected by the lower oxygen and thin air of higher elevations.
The results, which appeared this week in the Proceedings of the National Academy of Sciences (PNAS) Online Early Edition, show a clear decline in hummingbirds lifting ability with altitude, not unlike that seen in athletes competing at high elevations.
What this means for hummingbirds is less reserve power for the bursts of flight needed to chase off competitors or escape from predators, said researchers from the University of California, Berkeley, and the California Institute of Technology. "The costs of hovering flight are the same across elevations because hummingbirds compensate by having larger wings and by having a larger stroke amplitude," said study leader Douglas Altshuler, a postdoctoral fellow at Caltech. "However, that compensation doesnt come for free. They dont have as much excess power at high elevations as they do at low elevations."
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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What killed the patient? Determining causes of tree death during droughts and heatwaves
Image credit: Dr Timothy Brodribb UTAS
Researchers are using advanced imaging technologies similar to those used in hospitals to determine how vulnerable our trees are to drought and heatwaves. A new scientific review published In Nature outlines progress towards understanding the likely risks from droughts and heatwaves that combine to kill millions of trees around the world with spectacular effects on the environment.
Recent drought and heatwave conditions in northern Australia have killed more than 7000ha of mangrove forests, leaving these essential ecosystems stark, grey skeletons of trees. In California, the prolonged drought period has killed more than 100 million trees that increase the intensity of wildfires and impact on the region’s beauty, tourism and environmental health.
Dead trees, of course, cannot store carbon out of the air and the enormous numbers of dead trees release large quantities of stored carbon back into the air as they are burned or decay, further amplifying the effects of rising carbon dioxide.
In this research review released by Western Sydney University’s Hawkesbury Institute for the Environment and its international research team, scientists are using advanced technologies such as Medical Resonance Imaging (MRI) to peer into living trees and map how increasing dehydration of the trees results in the progressive dieback of leaves and branches, eventually causing the trees to be unable to move water through the stems. As the trees weaken, they become susceptible to insect and disease attacks which ultimately can kill the tree outright.
“Climatic changes are expected to increase the frequency and intensity of droughts and the combination of heat and dry really stresses even the hardiest trees”, explains Associate Professor Brendan Choat, lead author on the review.
Image credit: Prof Norman Duke, James Cook University
“If we can work out, using non-invasive methods like MRIs, the point at which trees become too dehydrated to survive then we can establish a dataset that can be used in the field to tell if a tree is reaching the point of no return”, he explains.
Trees are only able to move water to the tops of their branches if there is enough water in the soil and if they can preserve the column of water in their stems without bubbles or breakages. Most trees are able to maintain this flow of water but extreme demand for water during heat coupled with increasing soil dryness can mean that the flow can be interrupted. This can result in the death of leaves, then branches and ultimately the whole tree.
“Knowing the limits of individual tree species puts us in a good position to understand how vulnerable trees are to death”, says Assoc Prof Choat.
“Access to imaging facilities such as the Australian Synchrotron are essential for conserving our environments and play a crucial role in ensuring we are ahead of a rapidly changing world climate”.
Nature Paper: https://www.nature.com/articles/s41586-018-0240-x (opens in a new window)
28 June 2018
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It’s been a flying start for the Western Sydney University Solar Car team who have won the first stage of American Formula Sun Grand Prix Solar Challenge. | <urn:uuid:236d8be4-9cfe-470a-b3b9-2d755f9dfe07> | 3.3125 | 745 | News (Org.) | Science & Tech. | 32.283 | 95,558,655 |
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Use the equations below:
4) A wooden target of mass 2.00kg is suspended from a branch so that it swings freely. The target is hit by an arrow of mass 0.10kg travelling horizontally and the arrow embeds itself in the centre of the target. The target swings upwards, with its centre of mass rising by 0.60m. Use 9.81 as the acceleration for gravity.
A) Calculate the gain in gravitational energy by the target and arrow combination.
B) Calculate the velocity of the arrow and target immediately after the impact.
C) Calculate the velocity of the arrow immediately before the impact.
D) Determine if the collision is elastic or inelastic and why.
This one is a really tricky one so please write out in full, and no symbols please as i dont understand when you do that just full words | <urn:uuid:e67b3bd5-4eda-4d20-8114-3fe08c31d443> | 3.359375 | 183 | Tutorial | Science & Tech. | 60.632409 | 95,558,672 |
Temporal range: Priabonian to Recent 35–0 Ma
|Chiasma species from Ennominae|
The geometer moths are moths belonging to the family Geometridae of the insect order Lepidoptera, the moths and butterflies. Their scientific name derives from the Ancient Greek geo γη or γαια 'the earth' and metron μέτρων 'measure' in reference to the way their larvae, or inchworms, appear to "measure the earth" as they move along in a looping fashion. A very large family, it has around 23,000 species of moths described, and over 1400 species from six subfamilies indigenous to North America alone. A well-known member is the peppered moth, Biston betularia, which has been subject of numerous studies in population genetics. Several other geometer moths are notorious pests.
Many geometrids have slender abdomens and broad wings which are usually held flat with the hind wings visible. As such, they appear rather butterfly-like, but in most respects they are typical moths; the majority fly at night, they possess a frenulum to link the wings, and the antennae of the males are often feathered. They tend to blend into the background, often with intricate, wavy patterns on their wings. In some species, females have reduced wings (e.g. winter moth and fall cankerworm).
Most are of moderate size, about 3 cm (1.2 in) in wingspan, but a range of sizes occur from 10–50 mm (0.39–1.97 in), and a few species (e.g., Dysphania) reach an even larger size. They have distinctive paired tympanal organs at the base of the abdomen (lacking in flightless females).
The name "Geometridae" ultimately derives from Latin geometra from Greek γεωμέτρης ("geometer, earth-measurer"). This refers to the means of locomotion of the larvae or caterpillars, which lack the full complement of prolegs seen in other lepidopteran caterpillars, with only two or three pairs at the posterior end instead of the usual five pairs. Equipped with appendages at both ends of the body, a caterpillar clasps with its front legs and draws up the hind end, then clasps with the hind end (prolegs) and reaches out for a new front attachment - creating the impression that it measures its journey. The caterpillars are accordingly called loopers, spanworms, or inchworms after their characteristic looping gait. The cabbage looper and soybean looper are not inchworms, but caterpillars of a different family. In many species of geometer moths, the inchworms are about 25 mm (1.0 in) long. They tend to be green, grey, or brownish and hide from predators by fading into the background or resembling twigs. Many inchworms, when disturbed, stand erect and motionless on their prolegs, increasing the resemblance. Some have humps or filaments. They are gregarious and are generally smooth. Some eat lichen, flowers, or pollen, while some, such as the Hawaiian species of the genus Eupithecia, are even carnivorous. Certain destructive inchworms are called cankerworms.
The placement of the example species follows a 1990 systematic treatment; it may be outdated. Subfamilies are tentatively sorted in a phylogenetic sequence, from the most basal to the most advanced. Traditionally, the Archiearinae were held to be the most ancient of the geometer moth lineages, as their caterpillars have well-developed prolegs. However, it now seems that the Larentiinae are actually older, as indicated by their numerous plesiomorphies and DNA sequence data. They are either an extremely basal lineage of the Geometridae – together with the Sterrhinae –, or might even be considered a separate family of Geometroidea. As regards the Archiearinae, some species that were traditionally placed therein actually seem to belong to other subfamilies; altogether it seems that in a few cases, the prolegs which were originally lost in the ancestral geometer moths re-evolved as an atavism.
- Birch mocha, Cyclophora albipunctata
- False mocha, Cyclophora porata
- Maiden's blush, Cyclophora punctaria
- Riband wave, Idaea aversata
- Small fan-footed wave, Idaea biselata
- Single-dotted wave, Idaea dimidiata
- Small scallop, Idaea emarginata
- Idaea filicata
- Dwarf cream wave, Idaea fuscovenosa
- Rusty wave, Idaea inquinata
- Purple-bordered gold, Idaea muricata
- Bright wave, Idaea ochrata
- Least carpet, Idaea rusticata
- Small dusty wave, Idaea seriata
- Purple-barred yellow, Lythria cruentaria (formerly in Larentiinae)
- Vestal, Rhodometra sacraria
- Common pink-barred, Rhodostrophia vibicaria
- Middle lace border, Scopula decorata
- Cream wave, Scopula floslactata
- Small blood-vein, Scopula imitaria
- Lewes wave, Scopula immorata
- Lesser cream wave, Scopula immutata
- Mullein wave, Scopula marginepunctata
- Zachera moth, Semiothisa zachera
- Blood-vein, Timandra comae
- Eastern blood-vein, Timandra griseata
Desmobathrinae – pantropical
Geometrinae – emerald moths, about 2,300 named species, most tropical
Ennominae – about 9,700 species, including some defoliating pests, global distribution
Geometridae genera incertae sedis include:
Fossil Geometridae taxa include:
- Robin McLeod, John; Balaban, Jane; Moisset, Beatriz; Entz, Chuck (April 27, 2009). "Family Geometridae - Geometrid Moths". BugGuide. Retrieved April 2, 2011.
- "Lepidoptera Barcode of Life". Retrieved 2017-07-11.
- Scoble, M.J. (1999) (in German), Geometrid Moths of the World: a catalogue (Lepidoptera, Geometridae). Vol. 1 and 2, Stenstrup: CSIRO Publishing and Apollo Books, p. 1016
- Õunap, Erki; Viidalepp, Jaan; Saarma, Urmas (2008). "Systematic position of Lythriini revised: transferred from Larentiinae to Sterrhinae (Lepidoptera, Geometridae)". Zoologica Scripta. 37 (4): 405–413. doi:10.1111/j.1463-6409.2008.00327.x.
- Young, Catherine J. (2008). "Characterisation of the Australian Nacophorini using adult morphology, and phylogeny of the Geometridae based on morphological characters" (PDF). Zootaxa. 1736: 1–141.
- Cockerell, T. D. A. (1922). "A fossil Moth from Florissant, Colorado". American Museum Novitates. 34: 1–2.
- Hausmann, A. (2001): The geometrid moths of Europe. Apollo Books.
- Minet, J. & Scoble, M. J. (1999): The Drepanoid / Geometroid Assemblage. In: N. P. Kristensen (ed.): Handbuch der Zoologie. Eine Naturgeschichte der Stämme des Tierreiches / Handbook of Zoology. A Natural History of the phyla of the Animal Kingdom (Vol. 4: Arthropoda: Insecta. Part 35: Lepidoptera, Moths and Butterflies vol. 1: Evolution, Systematics, and Biogeography): Chapter 17. Walter de Gruyter, Berlin & New York.
- Scoble, M. J. (ed.) (1999): Geometrid Moths of the World: A Catalogue. CSIRO Publishing. ISBN 0-643-06304-8 | <urn:uuid:e0e97506-afb8-4e1d-9144-678a987ad76f> | 4.125 | 1,856 | Knowledge Article | Science & Tech. | 43.034536 | 95,558,682 |
Warming streams and rivers could be disproportionately contributing to the amount of planet-warming greenhouse gases, according to a new study.
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Scientists flew through the plumes of smoke rising from the Yorkshire moor fires to sample pollution levels.
Sea-level rise will endanger valuable salt marshes across the United Kingdom by 2100 if greenhouse gas emissions continue unabated, according to an international study co-authored by a Rutgers University-New Brunswick professor.
California greenhouse gas emissions fell below 1990 levels, meeting an early target years ahead of schedule and putting the state well on its way toward reaching long-term goals to fight climate change, officials said Wednesday.
One of the biggest freshwater reservoirs in the world is, literally, up in the air. | <urn:uuid:b41c093d-9ff8-4ff3-a133-753ab20532ff> | 3.125 | 263 | Content Listing | Science & Tech. | 36.006149 | 95,558,684 |
TAMPA (CBS Tampa) – NASA is expanding its efforts to use 3d printing to explore space. The agency already uses the technique to make rocket engine parts, a pizza maker, and physical photos from the Hubble Space Telescope.
One NASA engineer is attempting to become the first person to build an entire space camera using only 3d printed parts, reports Space.com.
“As far as I know, we are the first to attempt to build an entire instrument with 3d printing,” said Jason Budinoff, an aerospace engineer at NASA’s Goddard Space Flight Center in Maryland.
He is building a 2 inch camera for a miniature satellite called a cubesat.
In order to prove its space worthiness, the camera will have to pass vibration and thermal-vacuum tests that will simulate the experience of being blasted into space.
Budinoff’s 3d printing process starts when a laser melts a pile of metal powder. The computer then fuses the melted metal into a single layer of the overall design.
Then the layers are assembled, like slices of bread, to create the needed part.
If successful, Budinoff says it may be possible to build entire spacecraft using 3d printing techniques.
“I basically want to show that additive-machined instruments can fly,”Budinoff said in the same statement. “We will have mitigated the risk, and when future program managers ask, ‘Can we use this technology?’ we can say, ‘Yes, we already have qualified it.'”
(TM and © Copyright 2014 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2014 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)
- Dolly Parton on Christians condemning homosexuals: 'The sin of judging is just as bad as any other sin'
Get our daily email with news, sports and more - CLICK HERE | <urn:uuid:fbec5af3-a9f4-4f2c-87c9-1bff280aeb6b> | 3.3125 | 421 | News Article | Science & Tech. | 49.746208 | 95,558,705 |
National Center for
1VY8: Crystal Structure Of The E. Coli Crispr Rna-guided Surveillance Complex, Cascade
Clustered regularly interspaced short palindromic repeats (CRISPRs) are essential components of RNA-guided adaptive immune systems that protect bacteria and archaea from viruses and plasmids. In Escherichia coli, short CRISPR-derived RNAs (crRNAs) assemble into a 405 kDa multi-subunit surveillance complex called Cascade (CRISPR-associated complex for antiviral defense). Here, we present the 3.24 A resolution x-ray crystal structure of Cascade. Eleven proteins and a 61-nucleotide crRNA assemble into a sea-horse-shaped architecture that binds double-stranded DNA targets complementary to the crRNA-guide sequence. Conserved sequences on the 3'- and 5'-ends of the crRNA are anchored by proteins at opposite ends of the complex, while the guide sequence is displayed along a helical assembly of six interwoven subunits that present 5-nucleotide segments of the crRNA in pseudo A-form configuration. The structure of Cascade suggests a mechanism for assembly and provides insights into the mechanisms of target recognition. | <urn:uuid:4ffca87d-dde6-47a5-9d3c-5fa7a98e63af> | 2.53125 | 253 | Knowledge Article | Science & Tech. | 23.682267 | 95,558,720 |
SOUTH AUSTRALIAN BUTTERFLIES
The mystery of migration
The following is an edited version of an article prepared for the City of Marion Council Magazine, City Limits Spring Issue October 2002.
It will soon be time for migrating butterflies to start their annual migrations from the northern areas of South Australia. Most will fly south. Some will make it to Marion, where most will simply pass through and continue on flying south, but a few will stay to take up residence.
Certain groups of butterflies, such as the whites and yellows, and brush-foot butterflies, are known to form large migratory groups. The Caper White is one of those butterflies. It was this butterfly that recently passed through Marion in the thousands during 1999. Every year, these butterflies fly south during late spring from their breeding grounds in the North Flinders Ranges, and the inland areas of NSW and Qld, eventually reaching the suburbs of Adelaide. In most years only a few reach Adelaide, while infrequently, phenomenally large groups of the butterflies make it to Adelaide. The year 1999 was one of the phenomenal years, making it a once in a lifetime occasion for Marion residents. Although the butterflies usually fly south, they can actually disperse in any direction and migrations have been reported in Sydney and Brisbane, and occasionally they even reach Tasmania. Yet it is not known why they should fly south to colder areas where their caterpillar foodplants do not exist.
There have been no investigations into these migrations in Australia. For example, it is not known exactly from where they originate, how long the migrations take, how fast individuals fly, how far can they travel in a day, how do they navigate, how do they all synchronize their flight, does the entire migration occur as a single mass or does the group build up gradually along the chosen route, etc? For the interest of readers an attempt has been made to assemble the fragments of information received from the public relating to the big Caper White migration of 1999.
On the 3 September 1999, spring was heralded by a gale force north wind in South Australia. On the September 6 the first Caper White butterflies for the season were noticed as odd individuals in southern areas. Only odd individuals continued to be noticed through September and October. In early November, small local groups of the butterflies were seen collecting in forest and woodland areas of the Lower Southeast Region. November was an unusual month for wind direction in South Australia, with the wind direction being mostly from the hot northeast, and during the final week the wind was almost entirely from the northeast. Then on November 23 a very large migratory front of the butterflies was noticed in the Riverland flying from north to south, heading to the Southeast. The front amalgamated with the smaller groups in the region, and they all continued flying south. Flocks started flying out to sea on November 26 and thousands of butterflies perished and were washed up on the beaches the following day. Then the migration turned west and by November 29 they started to reach Murray Bridge. Late in the afternoon, huge numbers inundated the southern coastal Fleurieu Peninsula, from Goolwa in the east to Victor Harbor and along the west side of the peninsula to as far north as Marion in suburban Adelaide. In many places they were coming in off the sea. They spent the night by the hundreds at the same areas, hanging in the bushes and settling on the ground like 'snow'. Some even came to night-lights. (Interestingly, nobody bothered to photograph the 'butterfly snow', so we cannot show you a picture!)
Caper White migration 1999
On November 30 the migration was in full swing through the entire Fleurieu Peninsula, where the migration front now changed direction to north-northeast. Those butterflies at Marion woke early, had a feed from available flowers, and then by 9.00 am were on their way again. At Victor Harbor they were still coming in off the sea from the southeast, and continuing on to Yankalilla. When flying in off the sea they were flying in small flocks or groups, of 20's to hundreds. Others on the east side of the peninsula were flying in flocks north through Goolwa and Currency Creek, while newcomers were still arriving at Goolwa from the southeast. Large numbers were also still flying in the Southeast at Carpenters Rocks and Robe, flying northwest towards Adelaide. The flights extended to Kangaroo Island and the butterfly was reported in large numbers over the entire length of the island. Some even reached southern Yorke Peninsula and southern Eyre Peninsula. Along the west side of the Fleurieu Peninsula they were generally flying north-northeast following the west side of the Mt Lofty Ranges. Both sexes were flying in the main migration. There were reports of many road kills, with magpies and other birds eating the carcasses. Late in the afternoon, estimates of numbers in the migration were made in the open spaces of Waite Arboretum, where a line of sight count over a 50 metre distance recorded 650 individuals per hour. In the late afternoon the butterflies were seen to be flying in off the sea along Adelaide's beaches, then settling in large numbers along the foreshore bushes to overnight. They had all gone by the next day.
December 1 was another hot day with a strong northeast wind. The Caper Whites were now migrating in lesser numbers through suburban Marion, flying into the wind along the hills face. Butterflies were still actively migrating through Goolwa, and large numbers were still flying in off the St Vincents Gulf. A check of numbers at the Waite Arboretum in the morning showed 440 individuals per hour crossing over a line of sight distance of 100 m, but by late afternoon only 60 individuals were crossing the 100 m distance in an hour.
December 2 was a very hot day with a very strong north wind, and the migration through Marion and Adelaide was mostly over, with just a few butterflies continuing to migrate in a north-northeast direction, but with just as many being carried back in a south direction by the wind. By December 3 the migration was essentially all over in Adelaide with just the odd butterfly seen. Where the migration went after Adelaide is not known, but they did not pass through the Riverland or Clare, and it is assumed they flew along the east side of the ranges, and headed back northeast to where they originated from. If they originated from inland NSW it would have been a round trip of 1300 km through Adelaide, but if the origin was Qld it would have been 3000 km and comparable to the migrations of the large brown Monarchs (Wanderers) in North America.
Their natural caterpillar foodplants such as the Tree Caper occur in the hot northern inland areas, but a couple of specimens are maintained in the Botanic Gardens and Waite Arboretum. During big migrations, the females deposit thousands of eggs on these trees as they pass through, producing caterpillars that often damage the foliage. Due to predation, very few of these caterpillars will actually produce new butterflies.
Other butterflies are also known to migrate in South Australia, and they usually do so in spring, flying in a general south direction. These migrations now occur almost unnoticed due to the reduced number of butterflies taking part in the migration, caused by the loss of inland breeding habitat. Historically, they once migrated in huge numbers, with the Painted Ladies once being so numerous as to darken the sky in Victoria. The migrant butterflies should start to be seen in Marion by mid August and they will continue throughout spring. Initially there will be Painted Ladies, Meadow Argus, Admirals, Lesser Wanderers, and the large Chequered Swallowtails, and later the Small Grass Yellows and the Caper Whites. The latter two will pass through Marion as there is no caterpillar foodplant present for the female butterflies to lay eggs. However, some of the previous butterflies will remain to lay eggs to produce new butterflies in parks and home gardens. Late in autumn most of the new butterflies will return to the northern breeding grounds.
The large brown Wanderer or Monarch butterfly, now established in Marion, is a notable migrant in North America where very large numbers migrate annually between Canada, and California and Mexico (in particular) where huge overwinter clusters can occur. Similar overwintering clusters once used to occur in the Adelaide Hills, but the removal of its caterpillar milkweed foodplants has now significantly reduced numbers of this butterfly. Large migrations of this butterfly do not occur in Australia. However, the butterfly is not endemic to Australia (as we do not have any suitable native foodplants for its caterpillars), but it immigrated to Australia from North America by island hopping across the Pacific Ocean.
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11. Metamorphic Rocks 2
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York U-led research studies how astronauts determine ‘up’ in space
Keeping upright in a low-gravity environment is not easy, and NASA documents abound with examples of astronauts falling on the lunar surface. Now, a new study by an international team of researchers led by York University professors Laurence Harris and Michael Jenkin, published today in PLOS ONE, suggests that the reason for all these moon mishaps might be because its gravity isn’t sufficient to provide astronauts with unambiguous information on which way is “up”.
“The perception of the relative orientation of oneself and the world is important not only to balance, but also for many other aspects of perception including recognizing faces and objects and predicting how objects are going to behave when dropped or thrown,” says Harris. “Misinterpreting which way is up can lead to perceptual errors and threaten balance if a person uses an incorrect reference point to stabilize themselves.”
Using a short-arm centrifuge provided by the European Space Agency, the international team simulated gravitational fields of different strengths, and used a York-invented perceptual test to measure the effectiveness of gravity in determining the perception of up. The team found that the threshold level of gravity needed to just influence a person's orientation judgment was about 15 per cent of the level found on Earth – very close to that on the moon.
The team also found that Martian gravity, at 38 per cent of that on Earth, should be sufficient for astronauts to orient themselves and maintain balance on any future manned missions to Mars.
“If the brain does not sense enough gravity to determine which way is up, astronauts may get disoriented, which can lead to errors like flipping switches the wrong way or moving the wrong way in an emergency,” says Jenkin. “Therefore, it’s crucial to understand how the direction of up is established and to establish the relative contribution of gravity to this direction before journeying to environments with gravity levels different to that of Earth.”
This work builds upon results obtained in long-duration microgravity by Harris and Jenkin and other members of York’s Centre for Vision Research on board the International Space Station during the Bodies in the Space Environment project, funded by the Canadian Space Agency.
York University is helping to shape the global thinkers and thinking that will define tomorrow. York U’s unwavering commitment to excellence reflects a rich diversity of perspectives and a strong sense of social responsibility that sets us apart. A York U degree empowers graduates to thrive in the world and achieve their life goals through a rigorous academic foundation balanced by real-world experiential education. As a globally recognized research centre, York U is fully engaged in the critical discussions that lead to innovative solutions to the most pressing local and global social challenges. York U’s 11 faculties and 27 research centres are thinking bigger, broader and more globally, partnering with 288 leading universities worldwide. York U's community is strong − 55,000 students, 7,000 faculty and staff, and more than 250,000 alumni.
Media Contact: Robin Heron, Media Relations, York University, 416 736 2100 x22097/ email@example.com
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What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
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Catalytic converters for cleaning exhaust emissions are more efficient when they use nanoparticles with many edges. This is one of the findings of a study carried out at DESY’s X-ray source PETRA III. A team of scientists from the DESY NanoLab watched live as noxious carbon monoxide (CO) wa ... more
Periodic modulation tweaks innovative particle acceleratorsNew method can enhance beam quality of plasma cells
Simulation of the plasma wave following the laser pulse (red). The electron bunch is visible as a bright patch near the valley of the wave.
Scientists in Hamburg have come up with an ingenious way of improving so-called plasma accelerators, which are considered promising candidates to become the particle accelerators of the future. The quality of the electron beam produced by these innovative particle accelerators can be substantially improved by adding an oscillating component, as researchers from DESY’s Accelerators and Particle Physics divisions, together with a group headed by Andreas R. Maier from the University of Hamburg.
Simulation of the plasma wave following the laser pulse (red). The electron bunch is visible as a bright patch near the valley of the wave. Credit: Sören Jalas, Universität Hamburg “Plasma accelerators can achieve up to a thousand times higher accelerations than the most cutting-edge machines in use today,” says Reinhard Brinkmann, the director of DESY’s Accelerators division, on whose proposal the study was based. “This makes it possible to build more compact and more powerful devices for a wide range of applications, from fundamental research through to medicine. However, the technology is still in its very early experimental stages, and we will have to solve a number of problems before it can be used in applications.”
In a plasma accelerator, a wave is produced inside a thin capillary containing an electrically charged gas, known as a plasma. This gas could be hydrogen, for example, subjected to extremely intense and short laser pulses. “These laser pulses plough their way through the gas as thin disks, wrenching the electrons away from the hydrogen molecules and sweeping them aside like a snow plough,” explains Andreas Maier, who works at the Center for Free-Electron Laser Science (CFEL), which is jointly run by DESY, the University of Hamburg und the Max Planck Society. “Electrons in the wake of the pulse are accelerated by the positively charged plasma wave in front of them – much like a wakesurfer riding the wave behind a boat.”
The acceleration experienced is not the same for all the electrons, however, but depends on their precise position on the wave. Particles that are further forward are accelerated less than those riding further behind. The result is an unfavourably wide spread in the particles’ energies. “This leads to a similar problem to that encountered when focusing light made up of many different colours,” explains Maier. “A lens is only ever ideal for a single colour. Similarly, the electrons can only be focussed perfectly for a very specific energy. This means that reducing the so-called energy spread is one of the most important problems facing plasma accelerators.”
The solution proposed by Reinhard Brinkmann was to allow the electrons to swing to and fro across the trough of the wave. As a result, first one side of the electron bunch is accelerated more, then the other. On average, the two effects balance each other so that all the electrons experience the same acceleration – the energy spread shrinks dramatically. Also, during the process, the signs of the focusing forces alternate. This method of “alternating gradient focusing” is well-established in conventional accelerators, allowing them to produce stable particle paths. Apart from leading to a small energy spread, the method also ensures that the beam is very narrowly confined (i.e. it has a low emittance).
Achieving this is not that simple, however, since the entire plasma wave is just 0.1 millimetres or so in length, and the electrons cannot simply be moved back and forth in the short time necessary. “Manipulating the electrons is very difficult,” says Maier. So the physicists came up with an alternative: instead of moving the electrons around, the plasma wave itself can be pushed to and fro, which is much easier to control. To do this, the gas-filled capillary must consist of alternating high- and low-density zones, which is achieved by positioning several nozzles along the capillaries, themselves a few millimetres long, and injecting gas through the nozzles. Each jet produces a zone of high-density gas inside the capillaries. Because of the fluctuating density, the wavelength of the plasma wave also fluctuates, so that it shifts with respect to the electrons. As a result, the particles sometimes ride further forward, and sometimes further back on the wave.
“This means that we can modify macroscopic parameters, such as the pressure in the hydrogen inlet, to influence the electron beam on a micrometre scale,” says Maier. “We are hoping that the principle we have come up with will give us direct control over the accelerating field. This would be a crucial step towards the development of plasma accelerators.” The scientists have carried out detailed simulations of their method on the JURECA supercomputer at the Jülich Research Centre, among others. However, a practical test still needs to be conducted. In a first step, the physicists want to try out the underlying concept on the experimental laser plasma accelerator LUX and influence the electrons directly by specifically controlling the plasma density in the capillaries. LUX is jointly operated by DESY and the University of Hamburg, as part of their LAOLA collaboration.
R. Brinkmann, N. Delbos, I. Dornmair, M. Kirchen, R. Assmann, C. Behrens, K. Floettmann, J. Grebenyuk, M. Gross, S. Jalas, T. Mehrling, A. Martinez de la Ossa, J. Osterhoff, B. Schmidt, V. Wacker, and A. R. Maier; "Chirp Mitigation of Plasma-Accelerated Beams by a Modulated Plasma Density"; Phys. Rev. Lett.; 2017
- particle accelerators
- particle physics
- Deutsches Elektrone…
- Universität Hamburg
At DESY's X-ray source PETRA III, scientists have followed the growth of tiny wires of gallium arsenide live. Their observations reveal exact details of the growth process responsible for the evolving shape and crystal structure of the crystalline nanowires. The findings also provide new ap ... more
An international team of scientists has developed a new experimental method at the FLASH X-ray laser which allows the sequence of events involved in a process to be observed using a single, ultrashort pulse of light from FLASH. Their method is called “X-ray streaking” and enables researcher ... more
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- Electron spectrometer deciphers quantum mechanical effects | <urn:uuid:d42e51d9-23f1-4943-9b25-065a853b9077> | 2.75 | 1,556 | News Article | Science & Tech. | 38.502902 | 95,558,764 |
Liquid scintillation measurement of40K for the education on radioactivity
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Liquid scintillation counting of40K in ordinary potassium propionate is a highly suitable experimental task in the general education on radioactivity. The counting efficiency is about 90%, depending little on the measurement conditions. Potassium propionate is of suitable properties and can be easily obtained commercially or by conversion from other compounds. The result of counting, about 1,700 cpm/g, is highly impressive to many students, indicating the existence of40K radioactivity unexpectedly high in the normal nature, and can be used for the exercise of calculating our internal radiation exposure.
KeywordsRadiation Potassium Physical Chemistry Inorganic Chemistry Propionate
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- 1.C. M. Liderer, V. S. Shirley, Table of Isotopes, 7th ed., John Willey, New York, 1978, p. 90.Google Scholar
- 2.W. D. Ehmann, D. E. Vance, Radiochemistry and Nuclear Method of Analysis. John Willey, New York, 1991, p. 179.Google Scholar
- 3.J. C. Norma, J. Chem. Educ., 62 (1985) 439.Google Scholar
- 4.G. B. Forbes, Body Composition, in: Modern Nutrition in Health and Desease, Vol. 1,M. E. Shils, J. A. Olson andM. Shike (Eds), 8th ed., New York, 1994, p. 781.Google Scholar
- 5.Ref. 2,, p. 41.Google Scholar
- 6.T. Matsuura, R. Miki, The 33rd Annual Meeting on Radioisotopes in Physical Sciences and Industries, Tokyo, July, 1996, Abstract, p. 23.Google Scholar | <urn:uuid:eb4b3c11-b73e-4a02-8682-444b7eb8e86c> | 2.578125 | 394 | Truncated | Science & Tech. | 61.95231 | 95,558,770 |
Researchers from the University of Murcia and the Miguel Hernández University have studied tenebrionid beetles and how their numbers have declined as a result of increased ground moisture and salinity.
Researchers from Murcia and Alicante studied coleopterae (specifically carabid and tenebrionid beetles) in areas close to the Mar Menor from 1984 to 2003. Their research analysed changes in the species’ functional activity and structure, as well as in their response to changes in moisture and salinity levels in the coastal wetland area of Marina del Carmolí.
“The ecology and biodiversity of the hypersaline lagoon of the Mar Menor and its coastal wetlands are under threat from hydrological alterations caused by changes in land use within the basin, in particular increased irrigation,” SINC was told by Julia Martínez Fernández, a researcher from the University of Murcia’s Observatory on Sustainability in the Murcia Region.
In order to test the effects of irrigation, precipitation and the discontinuance of agriculture on these insects, the researchers took samples in 1984, 1992 and 2003. The results, published in the most recent issue of the Journal of Arid Environments, show that rises in the water table, increases in the length of periods during which the land is below water and of ground moisture levels have led to a decline in the abundance of tenebrionid beetles.
These beetles were used by the researchers as bio-indicators for arid systems. Tenebrionid beetles are a key link in the trophic chain of these ecosystems since they form the main foodstuff of numerous reptiles and birds. They were affected by the increase in ground moisture levels since they are better suited to semi-arid environments where they fulfil an important function as recyclers and “mobilisers of matter and energy in systems where microbial action is restricted”.
Changes in the make-up of species
Changes in hydrology and agricultural practices have led to an increase in carabid beetles, however, through the appearance of halophile (salinity tolerant) plants and halobiont plants, which grow in salty soils and only rarely in other locations, within the wetland area. Such plants were virtually absent between 1984 and 1992.
“The combination of the results obtained suggests that changing long-term trends in the water table and moisture conditions within the wetland are reflected by changes in the make-up of species,” said Martínez. The researcher added that the biggest impact on the wealth and diversity of species is due to “increases in moisture levels resulting from exceptionally rainy years, as well as successive changes derived from the discontinuance of farming”.
The changes being experienced within animal populations cannot be explained by variations in moisture or salinity alone, however. According to the researcher, the multi-faceted analysis revealed changes such as the existence of three groups of species. “The first of these are associated with more arid conditions (tenebrionids), the second are linked to greater homogeneity of moisture and salinity (carabids), and the third group is characterised by halobiont and halophile species, which are associated with permanently saline soils resulting from long-term changes in the water table.”
The appearance of this last group of salinity-tolerant plants has led to the introduction of species that are characteristic of unstable environments. The populations of animals that were to be found in 1984 were “species more typical of more stable environments”, said Martínez. She added that the increase in water from irrigation “is leading to a decline in the value of the habitats and in the uniqueness of the coastal wetlands of the Mar Menor, which make up protected areas that are even included in the Red Natura 2000 (network of natural areas of special environmental interest)”.
This study is part of a wider research programme looking into changes in the Mar Menor wetlands caused by changes in use of the basin, and their environmental implications.
SINC Team | alfa
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
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18.07.2018 | Materials Sciences
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By: PB Taylor, RA Navarro, M Wren-Sargent, JA Harrison and SL Kieswetter
251 pages, Figs, tabs, maps
Summarises the results of six years of wetland surveys at 180 South African wetlands. The report contains synthesis chapters that provide overviews of the status of and threats to South African wetlands. These are followed by the bulk of the report in two sections, one devoted to the wetlands, and one to the species which occurred at the wetlands.
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|Scientific Name:||Camptostemon schultzii Mast.|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Duke, N., Kathiresan, K., Salmo III, S.G., Fernando, E.S., Peras, J.R., Sukardjo, S., Miyagi, T., Ellison, J., Koedam, N.E., Wang, Y., Primavera, J., Jin Eong, O., Wan-Hong Yong, J. & Ngoc Nam, V.|
|Reviewer(s):||Polidoro, B.A., Livingstone, S.R. & Carpenter, K.E. (Global Marine Species Assessment Coordinating Team)|
This species is found in southeast Asia and Australia, where can be locally common. It is threatened by the loss of mangrove habitat throughout its range, primarily due to extraction and coastal development, and there has been an estimated 24% decline in mangrove area within this species range since 1980. Mangrove species are more at risk from coastal development and extraction at the extremes of their distribution, and are likely to be contracting in these areas more than in other areas. It is also likely that changes in climate due to global warming will further affect these parts of the range. Although there are overall range declines in many areas, they are not enough to reach any of the threatened category thresholds. This species is listed as Least Concern.
|Range Description:||This species is found in Indonesia, including Halmahera, Molluccas, Irian Jaya and Aru Island. It is also found in Australasia, including Northwest Australia, Northeast Australia, and Papua New Guinea.|
Native:Australia; Indonesia; Papua New Guinea
|FAO Marine Fishing Areas:|
Indian Ocean – eastern; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||This species is locally common in northern Australia and southern Papua New Guinea. For example, the species is common from Cape Bossut to Grove in the Northern Territory, Australia and is uncommon in the Joseph Onaparte Gulf region and the north coast of Melville Island (Wells 1983).|
|Current Population Trend:||Stable|
|Habitat and Ecology:||This species grows at the mid to low intertidal areas and along seashores. It is found in the intermediate to downstream estuarine zone in the low to mid-intertidal region. It is shade tolerant with a maximum porewater salinity of 75 ppt (Robertson and Alongi 1992). It grows into large trees in the Gulf of Papua. In Australia it thrives along dry shorelines (Duke 2006.)|
|Generation Length (years):||35|
|Use and Trade:||This species is used to treat skin infections by aboriginals in Australia (Duke 2006).|
Although local estimates are uncertain due to differing legislative definitions of what is a 'mangrove' and to the imprecision in determining mangrove area, current consensus estimates of mangrove loss in the last quarter-century report an approximately 24% decline in mangrove areas in countries within this species range since 1980 (FAO 2007).
All mangrove ecosystems occur within mean sea level and high tidal elevations, and have distinct species zonations that are controlled by the elevation of the substrate relative to mean sea level. This is because of associated variation in frequency of elevation, salinity and wave action (Duke et al. 1998). With rise in sea-level, the habitat requirements of each species will be disrupted, and species zones will suffer mortality at their present locations and re-establish at higher elevations in areas that were previously landward zones (Ellison 2005). If sea-level rise is a continued trend over this century, then there will be continued mortality and re-establishment of species zones. However, species that are easily dispersed and fast growing/fast producing will cope better than those which are slower growing and slower to reproduce.
In addition, mangrove area is declining globally due to a number of localized threats. The main threat is habitat destruction and removal of mangrove areas. Reasons for removal include cleared for shrimp farms, agriculture, fish ponds, rice production and salt pans, and for the development of urban and industrial areas, road construction, coconut plantations, ports, airports, and tourist resorts. Other threats include pollution from sewage effluents, solid wastes, siltation, oil, and agricultural and urban runoff. Climate change is also thought to be a threat, particularly at the edges of a species range. Natural threats include cyclones, hurricane and tsunamis.
|Conservation Actions:||There are no conservation measures specific to this species, but its range may include some marine and coastal protected areas. Continued monitoring and research is recommended, as well as the inclusion of mangrove areas in marine and coastal protected areas. In Indonesia, a number of protected areas and mangrove greenbelts have been designated. Detailed guidelines for sustainable forestry have been made, and there have been small reafforestation schemes in some areas (Spalding et al. 1997).|
|Citation:||Duke, N., Kathiresan, K., Salmo III, S.G., Fernando, E.S., Peras, J.R., Sukardjo, S., Miyagi, T., Ellison, J., Koedam, N.E., Wang, Y., Primavera, J., Jin Eong, O., Wan-Hong Yong, J. & Ngoc Nam, V. 2010. Camptostemon schultzii. The IUCN Red List of Threatened Species 2010: e.T178818A7616160.Downloaded on 21 July 2018.|
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On a windswept bluff above the Pacific Ocean, a dozen fourth- and fifth-graders are scattered among monkey flower and coyote bush shrubs. Teams of kids debate questions like how many leaves? How many flowers? By the end of their walk they have filled out a detailed questionnaire for each of 16 plants that had been marked by a round metal tag.
These kids, from Country Club Elementary in San Ramon, have spent four days staying at Fort Cronkhite in the Marin Headlands as part of the NatureBridge environmental field science program in the Golden Gate National Recreation Area. Today, they are helping out with real, grown-up science.
“What they’re doing is collecting data about how plants are changing in our park,” explains their instructor Elisa Litsky, a cheerful woman with balanced measures of authority and playfulness. “It’s like an exciting scavenger hunt.”
The kids on the bluff at Fort Cronkhite are just one facet of the California Phenology Project. The project, which is still in the pilot phase, has mobilized a small army of citizen-scientists to study differences in the timing of plant life cycles. So far, the project has hosted about 50 training sessions throughout California, involving about 600 people. And this is only the beginning. The pilot project is now active in seven parks in California but will eventually expand to 19 National Park Service sites as well as other public and private lands throughout the state.
The science of phenology studies the seasonal cycles in nature, such as when flowers bloom, insects hatch, and birds migrate. Gardeners and naturalists have been dabbling in these details for centuries, but the science of seasonal observation has taken on new urgency and import in the era of climate change.
Since the beginning of the 20th century, winters in the lower 48 states have been getting shorter and warmer on average, according to the Environmental Protection Agency. In the West, the average growing season has increased by three weeks, with most of that change occurring within the last three decades. This means that leaves bud, flowers bloom, and fruits ripen earlier. And plants aren’t the only things changing: Marmots in the Rocky Mountains are emerging earlier from hibernation and some birds have shifted their winter ranges as much as 400 miles to the north since the 1960s. Biologists speculate that the migrations of other species – from the localized journeys of amphibians to the long-distance flights of monarch butterflies – will be affected by climate change.
These changes lead scientists to worry about what they call “phenological mismatches” among species. Species and entire ecosystems depend on complex, intricately interlocked patterns of timing – many of which are poorly understood. Examples include songbirds that have evolved to migrate when the seeds or insects that they feed on are available – but what happens if the birds arrive and the seeds have already dried up? Or if an insect hatches but the flowers it pollinates haven’t bloomed yet? If every species were affected by climatic changes in exactly the same way, there wouldn’t be a problem. But they’re not: Some species might be responding to fixed signals, like the hours of daylight, while others may react to temperature or rainfall – cues that historically were linked but may no longer remain so. What happens when these go out of sync is the kind of question the project seeks to answer. By gathering long-term data sets at multiple sites across the state, scientists can test their models and confirm observed patterns of change.
But gathering information on such a large scale isn’t feasible using traditional methods. No one scientist, agency, or even group of researchers can provide the sheer number of people needed to collect the data needed to create a big-picture phenology database; especially not in an era of shrinking public funding.
This is where the citizen-scientists of the California Phenology Project (CPP) come in. The project is a collaboration between the National Park Service, the University of California Santa Barbara, and the National Phenology Network, which connects the people-power that can be channeled through the parks with the research needs of scientists. By creating a simple checklist that can be completed without specialized training, the project opens up data collection to a huge variety of people–whether they can help for a day or for a year. All the data is funneled back to researchers at UC Santa Barbara, where it is added to a growing database managed by the National Phenology Network, CPP’s older cousin.
“One of the huge benefits of building a citizen-science program is the ability to have more eyes, ears, and hands on the ground,” says Liz Matthews, a postdoctoral associate at UC Santa Barbara who is the sole full-time employee on the project. “We’re able to observe on a scale that simply wouldn’t be possible otherwise.”
Researchers already know that the same species of plant will bud and bloom at different times in different parts of California. Changes in elevation, latitude, and even microclimate – whether a plant is in a shaded ravine versus on the sunny hill a few yards away – can all affect phenology. And these regional differences can be seen right away in a project as big as this one. But observing the response to climate change will take time.
Eventually, CPP aims to document how changes in timing are related to environmental variation across both space and time – and to climate change. Researchers hope to correlate documented plant responses with specific climatic parameters such as temperature and rainfall, which have not been studied much in the western U.S. They will also examine clues as to whether species are at risk because they aren’t adapting well to the changing climate. But those results are several years, or even a decade, away.
In these early stages, the results are less dramatic but still valuable. Greenleaf manzanita in the Sierra foothills forms its flower buds a full year before they open, for example. And coyote bush can put out new leaves all year long – and especially after rainstorms. “It’s not at all what we expected to see,” says Matthews, adding that this type of phenological detail is not well known, even among ecologists, and has yet to be scientifically documented. “It really makes you get to know your local plants and the idiosyncratic patterns they show.”
A lot of the work that went into creating the CPP happened in the planning phase, which began in 2010. This involved developing tools for monitoring, such as data sheets and instructions. And because most phenology research up until now has been done on the East Coast with its distinct seasons, researchers also had to find methods to capture the more subtle phenological changes that happen in California’s mild climate.
One of the most formidable challenges was narrowing the state’s 5,000 plants down to a manageable list of candidates for monitoring. These had to be scientifically relevant, fairly common – and also reasonably straightforward for non-botanists to evaluate. Eventually the list was whittled down to 30 plants statewide, seven of which (coyote bush, coast live oak, blue oak, bay laurel, California buckeye, sticky monkey flower, California poppy) are currently being monitored at the Bay Area sites.
Another challenge is dealing with the errors that can crop up when you’re working with such a large and diverse volunteer labor force. For instance, bulbous green insect galls can look a lot like flower buds, and with tiny coyote bush leaves it’s hard to tell which ones are young and which are mature. Mistakes are bound to creep in, particularly with young kids or one-time volunteers. But, Matthews explains, one of the benefits of having a large amount of data is that a handful of mistakes won’t affect the results.
“With every citizen science program you understand that you probably have a higher rate of error,” says Matthews. “For student groups in particular, you’ve just got a ton of teachable moments. In our citizen science projects it’s always a balance between our science goals and our education goals.”
In the end, it’s worth spending a little more time analyzing the data to inspire a new generation of researchers and help people reconnect with the world around them, Matthews says. And it doesn’t hurt if they take home a lesson about climate change at the same time. “People get to see that the flora in their backyard reacts to climate,” she notes. “Then climate change is no longer a story about polar bears in the north — instead it’s, ‘What is the coyote bush doing in my backyard, and why does that matter?'”
At the John Muir National Historic Site in Martinez, three teenagers hike slowly up a muddy trail through mixed oak woodland on Mount Wanda. They are the park’s new interns and this is their first day on the job. For the next nine months, they will hike this trail twice each week, gathering phenology data on five different species: California buckeye, coyote bush, bay laurel, coast live oak, and blue oak.
Today, the three newcomers – Jenisse, Isaac, and Sierra – are being trained by one of their predecessors, Cheyanna, and park natural resource specialist Fernando Villalba. The group’s enthusiasm seems boundless. The two-mile-long hike takes nearly two hours because they stop to examine endless details: the moss at the base of a tree, a mushroom emerging from the soil, the tooth marks on a bay laurel nut that has been half-eaten by a squirrel. Cheyanna has a story to pass on to the new interns about one oak sapling that got trampled by a wayward horse; last year’s interns trimmed its broken branches and nursed it back to health. Now she regards its new green shoots with pride.
This is exactly the sort of relationship with nature that the phenology project hopes to encourage. Many people have never looked closely at a plant before, and even for avid outdoorspeople, data collection is often a new way of looking at nature.
“It’s a lot of fun to see the changes,” says Corny Foster, a spry retiree who is beginning her second year of collecting data on coyote bush at Crissy Field in San Francisco. Foster has been tending the site for over a decade, but now she can describe the quirks of the six bushes that she monitors as if they are old friends. One puts out more new leaves on one side than the other; a second is the prostrate form of the bush that had two flushes of flowers last year. A third lost most of its leaves during big winter storms.
“There was a time when there were still fruit dropping – and new leaves were popping out,” she adds with a laugh. “Things were pretty exciting for a while back in December.”
Whether learning the idiosyncrasies of single plants or just helping out for a day, hundreds of people participating in the CPP are getting to experience the thrill of watching – and recording – the small changes in their local ecosystems. Taken altogether, their work will help tell the story of larger ecological changes around the globe.
If you want to become a citizen scientist with the California Phenology Project, go to www.usanpn.org/cpp/participate. Volunteers can work with a national park nearby or do a project on their own.
Jacoba Charles is a freelance journalist based in the North Bay whose work has appeared in the New York Times, the Point Reyes Light, Bay Nature, and on Salon.com.
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The mammoth McApin Tree is not just the venerable elder in its grove. It’s thought the giant redwood holds within its fire-charred rings the surrounding forest’s formative secrets.
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Status: Not Listed
The spiny softshell turtle is one of the largest freshwater turtle species in North America. They can be distinguished from other turtle species by their carapace. Unlike most other turtles, their shell is soft, flat, and rubbery. The edges of the carapace are pliable with small spines (males have more than females). An adult female's carapace can be anywhere from 7 to 19 inches (18 to 48 centimeters) in length, while the male's is much smaller at 5 to 10 inches (13 to 25 centimeters) in length. The turtle’s nose is long and piglike, and its feet are fully webbed. This helps the spiny softshell turtle swim, since it spends most of its life in the water.
The spiny softshell turtle is spread throughout most of the United States, from the central-eastern U.S. to Wisconsin and Minnesota, and as far south as Mexico. Its habitat includes rivers, ponds, streams, and lakes with a sandy or muddy bottom and relatively little vegetation.
The spiny softshell turtle will eat almost anything in the water that will fit into its mouth, which may include aquatic insects, crayfish, and the occasional fish. They will bury themselves under a layer of mud at the bottom of a lake, with only their head sticking out, and catch prey as it passes by.
The spiny softshell turtle is a diurnal species. It spends most of the day in the sun, foraging for food. When it feels threatened, it buries itself in the sand and leaves just its head visible.
These reptiles are also able to breathe underwater due to the pharyngeal lining, cloacal lining, and skin.
Males nudge a female's head while swimming in an attempt to court her. With approval from the female, the male will swim above her, but will not clasp her with his claws like other turtle species. Spiny softshell turtles typically breed in May. Females lay anywhere from 4 to 38 eggs on sandbars or in loose soil. The eggs hatch sometime in August or September. They can live up to 50 years in the wild.
The spiny softshell turtle, in parts of its range, hibernates in mud for about half of the year.
Animal Diversity Web, University of Michigan Museum of Zoology
Michigan Department of Natural Resources
Nonindigenous Aquatic Species, United States Geological Survey
Place your order today for the themed box that delivers everything you need to create family memories while discovering nature and wildlife.Read More
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Climate change is allowing ticks to survive in greater numbers and expand their range—influencing the survival of their hosts and the bacteria that cause the diseases they carry.Read More
Tell your members of Congress to save America's vulnerable wildlife by supporting the Recovering America's Wildlife Act.Read More
You don't have to travel far to join us for an event. Attend an upcoming event with one of our regional centers or affiliates. | <urn:uuid:37696a44-2014-44d2-82df-ac87370e6508> | 3.421875 | 656 | Knowledge Article | Science & Tech. | 52.159081 | 95,558,832 |
Online Dictionary: translate word or phrase from Indonesian to English or vice versa, and also from english to english on-line.
Hasil cari dari kata atau frase: atomic number 94(0.01066 detik)
Found 1 items, similar to atomic number 94.
English → English (WordNet)
Definition: atomic number 94
atomic number 94
n : a solid silvery gray radioactive transuranic element whose
atoms can be split when bombarded with neutrons; found in
minute quantities in uranium ores but is usually
synthesized in nuclear reactors; 13 isotopes are known
with the most important being plutonium 239 [syn: plutonium, | <urn:uuid:e669aa33-92f7-4cd6-9ef1-8d275f5e2329> | 3.015625 | 145 | Structured Data | Science & Tech. | 22.413333 | 95,558,835 |
The study, which took a “citizen science” approach to data collection, is the first of its kind in Switzerland. More than 150 trained volunteers participated. In total, they examined 95,971 pieces of litter collected on the shores of Swiss rivers and lakes.
Rivers to the Sea
Intensive agriculture near the Mississippi has led to fertilizers leeching into the river, and ultimately the Gulf of Mexico, via soils and waterways. This has resulted in a huge oxygen-deprived dead zone in the Gulf that is now at its largest ever extent, covering an area greater than the state of New Jersey.
“Given their pervasive and persistent nature, microplastics have become a global environmental concern and a potential risk to human populations,” said Rachel Hurley from the University of Manchester and colleagues in their report, published in Nature Geoscience.
The equivalent of one garbage truck full of plastic waste is dumped into the world’s oceans every minute, equal to 8 million tons a year. New research suggests that 90 percent of that waste gets into the oceans through 10 major river systems.
Another reason global warming has not been too bad yet is because the ocean absorbs most of the earth’s excess heat. But oceans are warming due to greenhouse gas emissions. According to the National Oceanic and Atmospheric Administration, half of the increase in ocean heat content since 1865 has occurred over the past two decades. Warmer water holds less oxygen, but the respiration rate of animals (except for marine mammals) increases with temperature, so they need more oxygen at the same time that less is available. A warmer ocean has less turnover (vertical water movements), which normally brings nutrient-rich water up from deep water to the plankton that photosynthesize near the surface. With fewer nutrients, they photosynthesize less and animals can’t get enough food. | <urn:uuid:a6f54597-a7ba-4ca6-9c67-073f3505ef1a> | 3.6875 | 387 | Content Listing | Science & Tech. | 36.861626 | 95,558,861 |
Published in the journal Optics Letters, the researchers from the University’s Institute for Photonics and Advanced Sensing and the School of Chemistry and Physics describe how they have been able to produce 25 times more light emission than other lasers operating at a similar wavelength – opening the way for detection of very low concentrations of gases.
“This laser has significantly more power and is much more efficient than other lasers operating in this frequency range,” says Ori Henderson-Sapir, PhD researcher. “Using a novel approach, we’ve been able to overcome the significant technical hurdles that have prevented fibre lasers from producing sufficient power in the mid-infrared.”
The new laser operates in the mid-infrared frequency range – the same wavelength band where many important hydrocarbon gases absorb light.
“Probing this region of the electromagnetic spectrum, with the high power we’ve achieved, means we will be able to detect these gases with a high degree of sensitivity,” says Project Leader Dr David Ottaway. “For instance, it should enable the possibility of analysing trace gases in exhaled breath in the doctors’ surgery.”
Research has shown that with various diseases, minute amounts of gases not normally exhaled can be detected in the breath; for example, acetone can be detected in the breath when someone has diabetes.
Other potential applications include detection in the atmosphere of methane and ethane which are important gases in global warming.
“The main limitation to date with laser detection of these gases has been the lack of suitable light sources that can produce enough energy in this part of the spectrum,” says Dr Ottaway. “The few available sources are generally expensive and bulky and, therefore, not suitable for widespread use.”
The new laser uses an optical fibre which is easier to work with, less bulky and more portable, and much more cost effective to produce than other types of laser.
The researchers, who also include Jesper Munch, Emeritus Professor of Experimental Physics, reported light emission at 3.6 microns – the deepest mid-infrared emission from a fibre laser operating at room temperature. They have also shown that the laser has the promise of efficient emission across a large wavelength spectrum from 3.3-3.8 micron.
“This means it has incredible potential for scanning for a range of gases with a high level of sensitivity, with great promise as a very useful diagnostic and sensing tool,” says Dr Ottaway.
This research was supported by the State Government through the Premiers Science Research Foundation (PSRF).Media Contact:
Robyn Mills | Newswise
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
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Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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16.07.2018 | Earth Sciences | <urn:uuid:eba0d604-143b-4147-9231-2b55c8cecceb> | 3.28125 | 1,190 | Content Listing | Science & Tech. | 36.655732 | 95,558,862 |
1.5: Polygons. =convex and concave. p. 514-521. GSE’s. Primary.
=convex and concave
M(G&M)–10–2 Makes and defends conjectures, constructs geometric arguments, uses geometric properties, or uses theorems to solve problems involving angles, lines, polygons, circles, or right triangle ratios(sine, cosine, tangent) within mathematics or across disciplines or contexts (e.g., Pythagorean Theorem, Triangle Inequality Theorem).
Convex polygon: if you extend any side of the polygon, you will not go through the figure
Concave polygon: the opposite is true (it caves in)
+ + = 180
mA + mW+ mE=180o
(3x+5) + ( 8x+22) + (4x-12) = 180
15x + 15 = 180
15x = 165
x = 11
mA = 3(11) +5 = 38o
8x + 22
mW = 8(11)+22 = 110o
4x - 12
mE = 4(11)-12 = 32o
Triangle AWE is obtuse
1) Pick any vertex.
2) Make a darker point at it.
3) Connect that point to every other vertice in the polygon
Write down how many non-overlapping triangles are formed.
Extend any one side of the figure
The angle formed is the
exterior angle. It’s a linear pair
With the inside angle
HANDOUT on investigating polygons angles
Convex Polygon Number of Number of Sum of interior Sum of ext.
sides ‘s Angles Angles
The formula for finding the sum of the interior angles of any convex polygon is :
What is an example of a regular 4 sided polygon?
How about a 3 sided polygons?
Find the measure of angle N
of a regular polygon is 160. How many
sides does the regular polygon have? | <urn:uuid:93b14d8d-e08a-4076-87e9-166f0cac26cb> | 3.78125 | 454 | Tutorial | Science & Tech. | 68.902961 | 95,558,878 |
ESA’s orbiting X-ray observatory XMM-Newton has been used by a team of international astronomers to uncover part of the missing matter in the universe.
10 years ago, scientists predicted that about half of the missing ‘ordinary’ or normal matter made of atoms exists in the form of low-density gas, filling vast spaces between galaxies.
All the matter in the universe is distributed in a web-like structure. At dense nodes of the cosmic web are clusters of galaxies, the largest objects in the universe. Astronomers suspected that the low-density gas permeates the filaments of the web.
The low density of the gas hampered many attempts to detect it in the past. With XMM-Newton’s high sensitivity, astronomers have discovered its hottest parts. The discovery will help them understand the evolution of the cosmic web.
Only about 5% of our universe is made of normal matter as we know it, consisting of protons and neutrons, or baryons, which along with electrons, form the building blocks of ordinary matter. The rest of our universe is composed of elusive dark matter (23%) and dark energy (72%).
Small as the percentage might be, half of the ordinary baryonic matter is unaccounted for. All the stars, galaxies and gas observable in the universe account for less than a half of all the baryons that should be around.
Scientists predicted that the gas would have a high temperature and so it would primarily emit low-energy X-rays. But its very low density made observation difficult.
Astronomers using XMM-Newton were observing a pair of galaxy clusters, Abell 222 and Abell 223, situated at a distance of 2300 million light-years from Earth, when the images and spectra of the system revealed a bridge of hot gas connecting the clusters.
"The hot gas that we see in this bridge or filament is probably the hottest and densest part of the diffuse gas in the cosmic web, believed to constitute about half the baryonic matter in the universe," says Norbert Werner from SRON Netherlands Institute for Space Research, leader of the team reporting the discovery.
“The discovery of the warmest of the missing baryons is important. That’s because various models exist and they all predict that the missing baryons are some form of warm gas, but the models tend to disagree about the extremes,” adds Alexis Finoguenov, a team member.
Even with XMM-Newton’s sensitivity, the discovery was only possible because the filament is along the line of sight, concentrating the emission from the entire filament in a small region of the sky. The discovery of this hot gas will help better understand the evolution of the cosmic web.
"This is only the beginning. To understand the distribution of the matter within the cosmic web, we have to see more systems like this one. And ultimately launch a dedicated space observatory to observe the cosmic web with a much higher sensitivity than possible with current missions. Our result allows to set up reliable requirements for those new missions." concludes Norbert Werner.
ESA’s XMM-Newton Project Scientist, Norbert Schartel, comments on the discovery, “This important breakthrough is great news for the mission. The gas has been detected after hard work and more importantly, we now know where to look for it. I expect many follow-up studies with XMM-Newton in the future targeting such highly promising regions in the sky.”
Explore further: One of the densest clusters of galaxies in the universe is revealed | <urn:uuid:55edbf08-ee2f-4405-a49b-bd8ad4a093d0> | 3.8125 | 747 | News Article | Science & Tech. | 43.533797 | 95,558,886 |
Boy, 15, catches math error in golden ratio at 34-year-old exhibit at Boston museum
- Virginia high school student, Joseph Rosenfeld, was on family trip to the Museum of Science when he spotted the error
- He noticed minus signs in the equation for golden ratio, part of the Mathematica exhibit, where there should've been plus signs
- The sophomore left a message at the desk and later received letter saying equation would be corrected
- Museum released statement Tuesday saying its way of presenting golden ratio is 'less common - but no less accurate'
A 15-year-old high school student visiting Boston's Museum of Science has uncovered a math error in the golden ratio at a 34-year-old exhibit.
Virginia resident Joseph Rosenfeld was visiting the museum on a recent family trip in June when he saw something that appeared wrong with the equation for the golden ratio - part of the exhibit, Mathematica.
Rosenfeld, a sophomore at Handley High School, noticed minus signs in the equation where there should have been plus signs.
Virginia high school student Joseph Rosenfeld (pictured), 15, made the discovery while on a family trip to Boston's Museum of Science in June
'I was just really excited that I found an error,' he told Boston.com. 'That doesn't happen every day.'
After visiting the exhibit, he left a message at the desk and later received a letter from the museum's exhibit content developer, Alana Parkes, informing him the equation would be corrected.
Parkes wrote that the mistake had been there for a 'very long time' without being noticed.
'An unusual thing about Mathematica is that the whole exhibition is considered an artifact,' Parkes wrote in the letter, Boston.com reported.
Rosenfeld, a sophomore at Handley High School, noticed minus signs in the equation where there should have been plus signs. The golden ratio (left) in equation form is as follows: a/b = (a+b)/a = 1.6180339887498948420 …
Mathematica was created by the design team made up of Charles and Ray Eames, which opened at the museum in 1981
'This means that decisions about everything in the exhibition requires both Curatorial and Content Development consent (and most things can't be changed at all). It also means that this mistake has been there for a very long time.'
A permanent exhibit in the museum, Mathematica was created by the design team made up of Charles and Ray Eames, which opened at the museum in 1981, according to the museum's site.
On Tuesday, the Museum of Science released a statement saying they are not surprised the 'enterprising student' noticed the minus signs because the way the 'Museum presents the Golden Ratio in its exhibit is in fact the less common - but no less accurate - way to present it'.
'It's exciting that people around the country are talking about math and science and that, in the process, we learned something too,' the statement read.
Rosenfeld has since been invited by the museum to see the Science Behind Pixar exhibition.
He said he hopes to return to the state to attend the Massachusetts Institute of Technology.
On Tuesday, the Museum of Science released a statement saying they are not surprised the 'enterprising student' noticed the minus signs because the way the 'Museum presents the Golden Ratio in its exhibit is in fact the less common - but no less accurate - way to present it'
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