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An obscure swatch of human DNA once thought to be nothing more than biological trash may actually offer a treasure trove of insight into complex genetic-related diseases such as cancer and diabetes, thanks to a novel sequencing technique developed by biologists at Texas A&M University.
The game-changing discovery was part of a study led by Texas A&M biology doctoral candidate John C. Aldrich and Dr. Keith A. Maggert, an associate professor in the Department of Biology, to measure variation in heterochromatin. This mysterious, tightly packed section of the vast, non-coding section of the human genome, widely dismissed by geneticists as "junk," previously was thought by scientists to have no discernable function at all.
In the course of his otherwise routine analysis of DNA in fruit flies, Aldrich was able to monitor dynamics of the heterochromatic sequence by modifying a technique called quantitative polymerase chain reaction (QPCR), a process used to amplify specific DNA sequences from a relatively small amount of starting material. He then added a fluorescent dye, allowing him to monitor the fruit-fly DNA changes and to observe any variations.
Aldrich's findings, published today in the online edition of the journal PLOS ONE, showed that differences in the heterochromatin exist, confirming that the junk DNA is not stagnant as researchers originally had believed and that mutations which could affect other parts of the genome are capable of occurring.
"We know that there is hidden variation there, like disease proclivities or things that are evolutionarily important, but we never knew how to study it," Maggert said. "We couldn't even do the simplest things because we didn't know if there was a little DNA or a lot of it.
"This work opens up the other non-coding half of the genome."
Maggert explains that chromosomes are located in the nuclei of all human cells, and the DNA material in these chromosomes is made up of coding and non-coding regions. The coding regions, known as genes, contain the information necessary for a cell to make proteins, but far less is known about the non-coding regions, beyond the fact that they are not directly related to making proteins.
"Believe it or not, people still get into arguments over the definition of a gene," Maggert said. "In my opinion, there are about 30,000 protein-coding genes. The rest of the DNA -- greater than 90 percent -- either controls those genes and therefore is technically part of them, or is within this mush that we study and, thanks to John, can now measure. The heterochromatin that we study definitely has effects, but it's not possible to think of it as discrete genes. So, we prefer to think of it as 30,000 protein-coding genes plus this one big, complex one that can orchestrate the other 30,000."
Although other methods of measuring DNA are technically available, Aldrich notes that, as of yet, none has proven to be as cost-effective nor time-efficient as his modified-QPCR-fluorescence technique.
"There's some sequencing technology that can also be used to do this, but it costs tens of thousands of dollars," Aldrich said. "This enables us to answer a very specific question right here in the lab."
The uncharted genome sequences have been a point of contention in scientific circles for more than a decade, according to Maggert, a Texas A&M faculty member since 2004. It had long been believed that the human genome -- the blueprint for humanity, individually and as a whole -- would be packed with complex genes with the potential to answer some of the most pressing questions in medical biology.
When human DNA was finally sequenced with the completion of the Human Genome Project in 2003, he says that perception changed. Based on those initial reports, researchers determined that only two percent of the genome (about 21,000 genes) represented coding DNA. Since then, numerous other studies have emerged debating the functionality, or lack thereof, of non-coding, so-called "junk DNA."
Now, thanks to Aldrich's and Maggert's investigation of heterochromatin, the groundwork has been laid to study the rest of the genome. Once all of it is understood, scientists may finally find the root causes and possibly treatments for many genetic ailments.
"There is so much talk about understanding the connection between genetics and disease and finding personalized therapies," Maggert said. "However, this topic is incomplete unless biologists can look at the entire genome. We still can't -- yet -- but at least now, we're a step closer."
About Research at Texas A&M University: As one of the world's leading research institutions, Texas A&M is in the vanguard in making significant contributions to the storehouse of knowledge, including that of science and technology. Research conducted at Texas A&M represents annual expenditures of more than $820 million. That research creates new knowledge that provides basic, fundamental and applied contributions resulting in many cases in economic benefits to the state, nation and world. To learn more, visit http://research.tamu.edu.
Chris Jarvis, (979) 845-7246 or
or Dr. Keith A. Maggert, (979) 845-6610
Chris Jarvis | newswise
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The global dust storm currently raging on Mars shouldn’t disrupt the touchdown of NASA’s InSight lander this fall, agency officials said.
The planet-encircling storm is expected to subside by the time InSight arrives in November. But it won’t be a disaster for the new lander if the storm still swirls or if another one takes its place, officials said.
Rob Grover, leader of Insight’s Entry, Descent and Landing (EDL) team at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, told Space.com. [NASA’s InSight Mars Lander: Here’s 10 Surprising Facts]
Even if the storm subsides as expected, a dusty haze will likely still hang in the Martian atmosphere when InSight arrives, said Richard Zurek, chief scientist of the Mars Program Office at JPL. That haze could affect how InSight’s science instruments function, because it will prevent some sunlight from reaching the solar-powered lander. But touchdown should be fine, Zurek added.
Not a shock
Martian dust storms can pop up suddenly and last for weeks or even months. The current tempest contains several smaller, active dust storms and appears to have been triggered by a single local storm first observed at the end of May.
Previous NASA Mars missions have dealt with such storms or observed them up close.
When NASA’s Mariner 9 spacecraft reached Mars in November 1971, for example, it caught sight of a global dust storm that had been raging for several weeks. This was the second major storm of the year, researchers knew, because they had observed the first from Earth before the spacecraft’s Red Planet arrival. The Mariner 9 storm was huge and dramatic; it covered the entire Martian surface in dust, except the peaks of the tallest volcanoes.
Another major dust storm, comparable in size to the current one, raged across Mars when NASA’s Viking mission arrived in 1976. That, too, was the second global storm that year.
Landing in a storm
If the storm lasts for its maximum estimated duration, it should falL off just before InSight arrives, NASA officials have said. But it will likely leave traces in the Red Planet’s air regardless.
From an EDL standpoint, the biggest impact of the storm will be the way air is distributed in the Martian atmosphere, Grover said. During storms, dust heats the upper atmosphere, while the shaded lower atmosphere gets cooler. From the beginning of the InSight project, atmospheric modelers have provided a range of conditions that the lander might fly through during its critical EDL sequence, including dust storms, Grover said.
InSight will deploy a big parachute to slow down in the Martian atmosphere, then wrap up its descent by firing retro-rockets when close to the ground. A dusty atmosphere might require the parachute to be deployed as much as 0.9 miles (1.5 kilometers) lower than it would be in clear skies, Grover said. That would shave about 20 seconds off the 6.5-minute entry-to-landing timeline, he added.
When the parachute deploys, the suddenly slowed spacecraft will jerk backward, feeling what Grover called a “snatch force.” The goal is to keep that force under 15,000 lbs. (6,800 kilograms), he said. The amount of force is related to atmospheric density, which changes during or after a dust storm.
“We can tune how we’re actually going to fly on landing day,” Grover said. Minor changes could be sent to the spacecraft as soon as 2 hours before the landing, allowing the team to make adjustments based on the weather closer to the planet.
InSight also boasts an extra 0.2 inches (0.5 centimeters) of thermal protection on its heat shield, because a dust-thickened atmosphere generates more heat than clear skies do.
Like previous NASA Mars missions, InSight — which launched in early May — will use radar to assist with its landing. Ten minutes before it enters the atmosphere, the spacecraft will link with Earth to update its position and velocity based on radar observations. As it plunges into the (likely dusty) Martian atmosphere, InSight will rely on an inertial measurement unit (IMU), which uses an accelerometer and gyros to figure out the craft’s position as it flies through the atmosphere. The radar will then provide critical updates on the spacecraft’s altitude so that the lander knows where it is in relation to the ground.
“We can’t land successfully without the radar,” Grover said. This radar is capable of seeing through dust, allowing the mission to land safely even in a storm, he stressed.
Things will be different, by the way, for NASA’s Mars 2020 rover mission, which will rely on Terrain-Relative Navigation. Mars 2020 will use a camera to create a map of the landing site, comparing the landmarks in the images to those found on the craft’s onboard map. This new technology will allow the spacecraft to shift its direction to avoid landing on dangerous objects. Grover said that a dust storm would impede the device, making a safe landing a challenge. But, unlike InSight, Mars 2020 won’t arrive during dust-storm season.
On the ground
InSight — which is short forU —robot in depthThe stationary lander will help researchers map out the Red Planet’s interior by precisely measuring heat flow and analyzing tiny “marsquakes.”
Dust could affect InSight’s scientific work, because the lander relies on solar panels to power its instruments.
A new dust storm could affect “the deployment of instruments from this solar-powered platform,” Zurek said. The dust could also cover the panels after the instruments have been deployed.
“That’s the main worry, that the dust storm is going to cover your solar panels,” said Matt Siegler, a research scientist at the Planetary Science Institute in Arizona who works on InSight’s heat-probe instrument.
The problem is similar to the one NASA’s solar-powered Opportunity rover currently faces. The nearly 15-year old Opportunity has hunkered down during the global storm, likely entering a “low-power fault mode,” in which all subsystems other than the mission clock turn off. The mission clock is programmed to wake the computer to check its power levels.
The massive dust storm has blotted out the sun, keeping Opportunity from charging its batteries. The batteries don’t just run the instruments; they also keep the rover warm during the cold Martian nights. Without such heat, big problems can arise.
“Some soldered joint will get too cold and split, and then your computer dies,” Siegler said.
The dust storm itself could help keep Opportunity warm, because dust can trap heat close to the planet’s surface. Indeed, calculations by the Opportunity team suggest that temperatures won’t get cold enoughin the immediate future to freeze that rover out, NASA officials said last month.
When InSight lands, it should have enough power to keep its instruments warm for some time, Zurek said. Once the storm passes and the skies clear somewhat, the spacecraft will be able to begin its mission exploring the Martian interior.
In the meantime, scientists will keep their eyes on the enormous weather event.
“The current storm is still developing, and atmospheric scientists here at JPL are continuing to observe it,” Grover said. | <urn:uuid:6fa66b84-3934-4e80-93ba-51bddef572c7> | 2.703125 | 1,616 | News Article | Science & Tech. | 54.053967 | 95,533,603 |
Authors find that Giant South American river turtles have a repertoire of vocalizations for different behavioral situations, including caring for young
Turtles are well known for their longevity and protective shells, but it turns out these reptiles use sound to stick together and care for young, according to the Wildlife Conservation Society and other organizations.
This is an adult Giant South American river turtle. The turtle is the largest member of the side-necked turtle family and grows up to nearly three feet in length.
Credit: Photo credit: C. Ferrara/Wildlife Conservation Society
Scientists working in the Brazilian Amazon have found that Giant South American river turtles actually use several different kinds of vocal communication to coordinate their social behaviors, including one used by female turtles to call to their newly hatched offspring in what is the first instance of recorded parental care in turtles.
The study appears in a recent edition of the journal Herpetologica. The authors are: Camila Ferrara of the Wildlife Conservation Society; Richard C. Vogt of the Instituto Nacional de Pesquisas de Amazônia, and the Associação de Ictiólogos e Herpetólogos da Amazônia; Renata S Sousa-Lima of the Cornell Lab of Ornithology; Bruno M.R. Tardio of the Instituto Chico Mendez; and Virginia Campos Diniz Bernardes of the Instituto Nacional de Pesquisas de Amazônia, and the Associação de Ictiólogos e Herpetólogos da Amazônia.
"These distinctive sounds made by turtles give us unique insights into their behavior, although we don't know what the sounds mean," said Dr. Camila Ferrara, Aquatic Turtle Specialist for the WCS Brazil Program. "The social behaviors of these reptiles are much more complex than previously thought."
Some behaviors of the Giant South American river turtle have been well known for some time, including the tendency to aggregate in huge numbers during the nesting season. However, the mechanisms used by turtles to coordinate their activities have yet to be explained. This study focused on the sounds made by the turtles as a possible means of facilitating social behavior.
Working on the Rio Trombetas between 2009 and 2011, the research team captured 270 individual sounds made during 220 hours of recording made with both microphones and hydrophones when the turtles were swimming through the river. The scientists then conducted spectrographic analyses on the repertoire, which they subdivided into six different types of vocalization made by turtles during the nesting season, which begins as the reptiles leave the seasonally flooded forest for nesting beaches along river banks. The scientists also sought to correlate vocalizations with specific behaviors.
Sounds made by the turtles while migrating through the river or basking tended to be low frequency sounds, possibly to facilitate contact between turtles over longer distances. Vocalizations made during nesting tended to be higher frequency sounds, possibly because higher frequency sounds travel better in shallow water and in the air.
The highest diversity of sounds are used by females about to nest; the researchers theorize that the animals use these sounds to decide on a specific nesting site and to synchronize their movements (the turtles leave the water in a single-file procession).
The hatchling turtles themselves make sounds before they hatch and continue to do so as they clamber out of the nest chamber on the river beach. The sounds, the authors speculate, may stimulate group hatching. The females, in turn, vocalize in response to the nestling calls, perhaps guiding the nestlings into the water. These interactions—the first recorded instance of parental care in turtles—were featured in a 2012 study appearing in the Journal of Comparative Psychology.
Using sonic transmitters, the team also discovered that the hatchlings remain together and migrate with adult females for more than two months.
The Giant South American river turtle is the largest of the side-necked turtle family and grows up to 80 centimeters (nearly three feet) in length. The species is only found in the Amazon River basin and is now threatened by unregulated consumption of the turtles' meat and eggs.
"Groundbreaking studies such as this one can help us better understand the complex relationships between both individual animals and their environment," said Dr. Julie Kunen, Executive Director of WCS's Latin America and the Caribbean Program. "Protecting the still sizable populations of Giant South American river turtles will also enable us to conserve the behavioral richness of these reptiles for future study."
Research on the Giant South American river turtles is part of a new long-term WCS conservation program called Amazon Waters, an initiative focusing on the conservation of aquatic ecosystems and species.
The Wildlife Conservation Society works to save turtles and tortoises around the world. In 2012, WCS launched an organization-wide program to revive some of the most endangered turtle and tortoise species. Efforts include breeding programs at WCS's zoos in New York, head start programs abroad, and working with governments and communities to save species on the brink of extinction.
To access the study, click here:
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Deoxygenation due to climate change threatens marine life
Climate change has caused a drop in the amount of oxygen dissolved in the oceans in some parts of the world, and those effects should become evident across large parts of the ocean between 2030 and 2040, according to a new study led by researchers at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado.
Scientists expected a warming climate to sap oceans of oxygen, leaving fish, crabs, squid, sea stars, and other marine life struggling to breathe. But they had encountered difficulties in determining whether this anticipated oxygen drain was already having a noticeable effect.
"Loss of oxygen in the oceans is one of the serious side effects of a warming atmosphere, and a major threat to marine life," said NCAR scientist Matthew Long, lead author of the study. "Since oxygen concentrations in the ocean naturally vary depending on variations in winds and temperature at the surface, it's been challenging to attribute any deoxygenation to climate change. This new study tells us when we can expect the effect from climate change to overwhelm the natural variability."
The study is published in the American Geophysical Union journal Global Biogeochemical Cycles. The research was funded by the National Science Foundation (NSF).
Cutting through the natural variability
The entire ocean -- from the depths to the shallows -- gets its oxygen supply from the surface, either from the atmosphere or from phytoplankton, which release oxygen into the water through photosynthesis.
Warming surface waters, however, absorb less oxygen. And, in a double whammy, the absorbed oxygen has a more difficult time traveling deeper into the ocean. That's because as water heats up, it expands, becoming lighter than the water below it and less likely to sink.
Thanks to natural warming and cooling, oxygen concentrations at the sea's surface change constantly -- and deeper in the ocean, those changes can linger for years or decades.
For example, an exceptionally cold winter in the North Pacific would allow the ocean surface to soak up a large amount of oxygen. Thanks to the natural circulation pattern, that oxygen would then be carried deeper into the ocean, where it might still be detectable years later as it travels along its flow path.
On the flip side, unusually hot weather could lead to "dead zones" in the ocean, where fish and other marine life cannot survive.
To cut through this natural variability and investigate the impact of climate change, the research team -- including Curtis Deutsch of the University of Washington and Taka Ito of Georgia Tech -- relied on the NCAR-based Community Earth System Model, which is funded by NSF and the U.S. Department of Energy.
"This study shows how far comprehensive Earth System Models have come in the effort to quantify, along with relatively sparse observations, large-scale changes in oxygen in the oceans due to both natural variability and climate change," said Eric Itsweire, program director in NSF's Division of Ocean Sciences.
The scientists used output from a project that ran the model more than two dozen times for the years 1920 to 2100. Each individual run started with miniscule variations in air temperature. As the model runs progressed, those tiny differences grew and expanded, producing a set of climate simulations useful for studying questions about variability and change.
Using the simulations to study dissolved oxygen gave the researchers guidance on the degree to which concentrations may have varied naturally in the past. With this information, they could determine when ocean deoxygenation due to climate change is likely to become more severe than at any point in the modeled historic range.
The researchers found they could already detect deoxygenation caused by climate change in the southern Indian Ocean and parts of the eastern tropical Pacific and Atlantic basins.
They also determined that more widespread detection of deoxygenation caused by climate change would be possible between 2030 and 2040.
However, in some parts of the ocean, including areas off the east coasts of Africa, Australia, and Southeast Asia, deoxygenation caused by climate change would not become evident even by 2100.
Detecting a global pattern
The researchers also created a visual way to distinguish between deoxygenation caused by natural processes and deoxygenation caused by climate change.
Using the same model dataset, the scientists created maps of oxygen levels in the ocean, showing which waters were oxygen-rich and which were oxygen-poor. They found they could distinguish between oxygenation patterns caused by natural weather phenomena and the pattern caused by climate change.
The climate change pattern also became evident in the model runs around 2030, adding confidence to the conclusion that widespread deoxygenation due to climate change will become detectable around that time.
The maps could also be useful resources for deciding where to place instruments to monitor ocean oxygen levels in the future to get the best picture of climate change effects. Currently, ocean oxygen measurements are relatively sparse.
"We need comprehensive and sustained observations of what's going on in the oceans to compare with what we're learning from our models, and to understand the full effect of a changing climate," Long said.
Cheryl Dybas | EurekAlert!
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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.
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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.
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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.
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Bioengineering transfers methods from engineering sciences to organic materials and also includes findings from the field of IT. The highly complex building plans in biology are now decipherable and permit the targeted manipulation of tissue structures and even of entire living creatures. For example, DNA can be used as a digital data carrier, and 3D printing methods can produce replacement organs. Similarly, successful concepts from nature are copied and used to create new bionic products and technologies. In the long term, bioengineering will blur the borders between organic and non-organic components and increasingly find its way into our daily lives. | <urn:uuid:54b007a5-829c-4398-96f3-06ad30c648f4> | 3.03125 | 116 | Knowledge Article | Science & Tech. | 25.508238 | 95,533,674 |
The distribution of ideals in a number ring
We are going to exploit the geometric methods of chapter 5 to establish results about the distribution of the ideals of a number ring R. In a sense to be made precise shortly, we will show that the ideals are approximately equally distributed among the ideal classes, and the number of ideals with ‖I‖ ≤ t, t ≥ 0, is approximately proportional to t.
KeywordsFundamental Domain Principal Ideal Free Abelian Group Ideal Class Coset Representative
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Great Lakes biologists work to save lake trout
While biologists in Yellowstone National Park are working hard to remove lake trout from Yellowstone Lake, biologists in the Great Lakes area are working to save the fish.
Lake trout are native to the Great Lakes, and lake trout populations there are struggling. In Yellowstone Lake, lake trout are the illegally introduced non-native species. In the Great Lakes, lake trout are the native fish that are suffering because of non-native sea lamprey, an eel-shaped parasitic fish that have no natural predators in the Great Lakes.
Biologists in Yellowstone have teamed up with Great Lakes biologists who have been studying lake trout longer and have a better understanding of the fish.
The Great Lakes biologists can put to use the knowledge they've gained trying to save the fish and help biologists in Yellowstone kill the fish.
"It's the same science," said Lee Simard, a master's student at the University of Vermont who is working this summer in Yellowstone.
His adviser at UVM focuses on studying lake trout in the Great Lakes.
In the Great Lakes, researchers know that lake trout spawn, but they have a recruitment problem, meaning the eggs don't hatch or fry don't grow into adult fish at the rate they'd like.
In Yellowstone, Simard is using the same technology and tools his adviser uses in the Great Lakes.
Those tools include a sled-looking device that is dropped to the bottom of the lake and dragged along the lake bed. High-pressure jets shoot the lake bottom to stir up mud. A net catches the material stirred up by the jets.
"It's a good way to actively search for spawning areas," Simard said.
Simard runs the sled for about one to five minutes before raising it back into his boat to look for signs of spawning sites.
The sled has GoPro cameras attached to it so researchers can see what the lake bottom looks like in areas where they find spawning sites. That will help researchers gain a better understanding of what types of areas lake trout spawn in. | <urn:uuid:fdc9fd7f-921a-4ad9-b3b7-b31675f13fad> | 3.8125 | 435 | Truncated | Science & Tech. | 48.035588 | 95,533,729 |
'The animals are very delicate. They wouldn't survive a fall from any height,' explains Claire Rind from the University of Newcastle, UK. In 2006, Stanislav Gorb and his colleagues published a paper in Nature suggesting that tarantulas may save themselves from falling by releasing silk threads from their feet.
However, this was quickly refuted by another group that could find no evidence of the silk. Fascinated by spiders and intrigued by the scientific controversy, Rind decided this was too good a challenge to pass up and discovered that tarantulas shoot silk from their feet when they lose their footing. She publishes her results in The Journal of Experimental Biology at http://jeb.biologists.org/content/214/11/1874.abstract.
Teaming up with undergraduate Luke Birkett, Rind tested how well three ground-dwelling Chilean rose tarantulas kept their footing on a vertical surface. Gently placing one of the animals in a very clean aquarium with microscope slides on the floor, the duo cautiously upended the aquarium to see if the tarantula could hang on. 'Given that people said tarantulas couldn't stay on a vertical surface, we didn't want to find that they were right,' remembers Rind. But the spider didn't fall, so the duo gave the aquarium a gentle shake. The tarantula slipped slightly, but soon regained its footing. So the spider had held on against the odds, but would Rind find silk on the microscope slides?
Looking at the glass by eye, Rind couldn't see anything, but when she and Birkett looked closely under a microscope, they found minute threads of silk attached to the microscope slide where the spider had stood before slipping.
Next, Rind had to prove that the silk had come from the spiders' feet and not their web-spinning spinnerets. Filming the Chilean rose tarantulas as they were rotated vertically, Rind, Benjamin-James Duncan and Alexander Ranken disregarded any tests where other parts of the spiders' bodies contacted the glass and confirmed that the feet were the source of the silk. Also, the arachnids only produced their safety threads when they slipped.
But where on the spiders' feet was the silk coming from? Having collected all of the moulted exoskeletons from her Mexican flame knee tarantula, Fluffy, when she was young, Rind looked at them with a microscope and could see minute threads of silk protruding from microscopic hairs on Fluffy's feet. Next, the team took a closer look at moults from Fluffy, the Chilean rose tarantulas and Indian ornamental tarantulas with scanning electron microscopy and saw minute reinforced silk-producing spigots, which extended beyond the microscopic attachment hairs on the spiders' feet, widely distributed across the foot's surface. Rind also looked at the tarantula family tree, and found that all three species were only distantly related, so probably all tarantula feet produce the life-saving silk threads.
Finally, having noticed the distribution of the spigots, Rind realised that tarantulas could be the missing link between the first silk-producing spiders and modern web spinners. She explains that the spread of spigots on the tarantula's foot resembled the distribution of the silk spigots on the abdomen of the first silk spinner, the extinct Attercopus spider from 386 million years ago. The modern tarantula's spigots also looked more similar to mechanosensory hairs that are distributed over the spider's entire body, possibly making them an evolutionary intermediate in the development of silk spinning. So, not only has Fluffy settled a heated scientific debate but she also may be a link to the silk spinners of the past.
IF REPORTING ON THIS STORY, PLEASE MENTION THE JOURNAL OF EXPERIMENTAL BIOLOGY AS THE SOURCE AND, IF REPORTING ONLINE, PLEASE CARRY A LINK TO: http://jeb.biologists.org
REFERENCE: Rind, C., Birkett, C. L., Duncan, B.-J. A. and Ranken, A. J. (2011). Tarantulas cling to smooth vertical surfaces by secreting silk from their feet. J. Exp. Biol. 214, 1874-1879.
This article is posted on this site to give advance access to other authorised media who may wish to report on this story. Full attribution is required, and if reporting online a link to jeb.biologists.com is also required. The story posted here is COPYRIGHTED. Therefore advance permission is required before any and every reproduction of each article in full. PLEASE CONTACT firstname.lastname@example.org
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Indian marine scientists from the Zoological Survey of India (ZSI) found a dead coral reef from 10,000 years ago in the Gulf of Kutch, and decided to try and revive it. Corals were then transplanted from a similar environment in the Gulf of Mannar and these fragile creatures survived. Given the marine environment in the Gulf of Kutch, the scientists now intend using the region as a sanatorium for sick and stressed out corals.
The beginning of this story dates back to over 10,000 years ago when there was a large thriving coral reef in the Gulf of Kutch. The reef had a good diversity of stony corals and was dominated by Acropora Stag-horn branching corals. Sediments brought down by the rivers that flow through the Kutch area caused silt to settle on the coral beds, leading to the death of these branching corals.
Indian marine scientists found dead branching corals on the 42 islands around the Gulf of Kutch. Carbon dating enabled them to deduce that these branching corals had died some 10,000 years ago.
Dead Acropora Stag-horn corals strewn across an island
These scientists from ZSI did not leave the story unfinished here. “Through our various studies we have found that the sediment load flowing into the Gulf of Kutch, especially from the Indus river, has reduced due to the construction of dams and hence we decided to bring back to life the long vanished coral reef by transplanting the Acropora Stag-horn corals; they grow fast when compared to other coral species and help in increasing the fish population,” says Dr Ch. Satyanarayana, Scientist and Coral Taxonomist with ZSI.
India has four major coral reef regions – in the waters around the Andaman and Nicobar islands, the Lakshadweep islands, the Gulf of Mannar, and the Gulf of Kutch. Indian scientists have vast experience diving and carrying out research in reef regions around the country and around the world – they found that the environment in some parts of the Gulf of Mannar and the Gulf of Kutch is very similar.
So, they decided to restore the reef in the turbid waters of Kutch by transplanting corals from the waters of Mannar, which, to their surprise, was a success.
“This is for the first time in the world that biologists have managed to restore a reef that has been dead for thousands of years by transporting live corals from more than 2,000 km away and growing them in turbid waters,” says Dr. Kailash Chandra, director of ZSI.
One square km of the coral reef has been restored at the Marine National Park in the Gulf of Kutch. A technique similar to grafting new rose bushes, with twigs delicately taken from the mother plant, was used to restore this coral reef.
Corals are marine invertebrates that live in compact colonies. They are generally found in tropical waters and require a pristine environment to live and grow. Corals secrete a calcium carbonate skeleton for their own protection. Along with other calcium-secreting marine creatures, they form mountain-like structures underwater, which are called coral reefs.
Coral reefs are called ‘rain forests of the sea’ because of the diversity of life they harbour. They are home to many species of fish, support tourism, and are a huge resource for the pharmaceutical industry. They are indicators of climate change and act as a first line of defence against cyclones and tsunamis.
#MGChangemakers - Episode 2: THE 21-YEAR JOURNEY OF CHANGE | Driving India Into Future
Live Now #MGChangemakers Episode 2 : Touched by poverty, untouchability and atrocities against Musahar- the Mahadalit community of Bihar, Padma Shri Sudha Varghese decided to dedicate her life for their upliftment. Watch the video to learn about her inspirational journey & how she is ‘Driving India Into The Future’. #MGChangemakers powered by MG Motor India and supported by United Nations India. Show your support by donating now: http://bit.ly/Milap-MGChangemakersPosted by TheBetterIndia on Wednesday, July 18, 2018
“Corals are primitive animals, they have no heart or circulatory system. The water they live in must be clear so that sunlight penetrates. Corals have a photosynthetic algae which lives in their tissues, called zooxanthellae,” continues Dr Satyanarayana.
The zooxanthellae supply the coral with food, produce oxygen and help it eliminate waste. In turn, the coral gives, the algae a protected environment to live in and all the compounds they need for photosynthesis.
The project to study the coral reefs in Indian waters, which led to the transplantation of the Acropara corals in the Gulf of Kutch, was started in 2012 and is slated to go on till 2017. It is being funded by the World Bank. The scientists working on this project find it really interesting that the corals that have been transplanted from the Gulf of Mannar have survived and are thriving in the murky waters of the Gulf of Kutch.
“During the transportation of coral fragments from the donor site to the recipient site, utmost care had to be taken to make sure that the salinity, the pH level, the temperature and the oxygen level of the water, were exactly the same. We have used ‘jel ice’, which is usually used to preserve flowers, when transporting the corals from one end of the country to the other,” explains Dr Satyanarayana.
A qualified scuba diver himself, Dr Satyanarayana is being supported in this underwater project by Australian scientist Dr Carden Wallace, a world renowned Stag-horn coral expert, who had earlier trained him in coral taxonomy in the Museum of Tropical Queensland at Townsville, Australia. She was instrumental in helping him make the choice of corals to transplant to the Gulf of Kutch.
Given the success of this mission, ZSI scientists are seriously considering setting up a coral sanatorium in the Gulf of Kutch, for sick and stressed out corals from around the country.
“Rising temperatures of waters are causing many corals to get sick, which is called coral bleaching. We discovered that the corals of the Gulf of Kutch are less affected by global warming, when compared to other reef regions in the country. The sediments suspended in the waters help to give shade to the corals below, protecting them from the direct and harsh rays of the Sun. This helps corals in well circulated turbid water to have a better chance of survival when compared to corals growing in clear water,” says India’s coral expert.
Owing to global warming, heavy sedimentation and the increasing contamination level of water, many corals are dying around the world. Few people are aware of this problem, consequently there is not enough effort being made to save them. Much more awareness about corals and their usefulness to us has to be spread if these precious life forms are to be saved. . Since reefs are helpful to protect us from various natural hazards, it is for us to take care and protect them. | <urn:uuid:9f143ed4-4f4a-4e78-8a40-1675140b6fd0> | 3.53125 | 1,525 | News Article | Science & Tech. | 43.727196 | 95,533,732 |
Astronomers using a new instrument on the Very Large Telescope in Chile have directly imaged a newborn planet.
Our understanding of planet formation is often shrouded in theoretical models. But now, scientists have directly observed a new planet in the gaseous disk around a young star about 370 light-years from Earth.
The search for new planets often starts with a survey of the heavenly regions where stars are born. Scientists at the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany were doing just that when they focused their attention on the young star PDS 70. At 5 million to 6 million years old it is still accreting mass from its surrounding disk of gas and dust. The star —which is about the size of our Sun — was first discovered in 1992, but scientists using the Very Large Telescope’s SPHERE instrument hoped to see new details in its disk. To their surprise, they found a gap — a dark path — in the middle of the glowing gaseous swirl.
To confirm the planet’s presence, scientists used SPHERE to block out the light from the star, whose glare hides surrounding features. When researchers could see the dark path more clearly, they found a point source of light exactly in the location where a planet would be expected to form, the group reports in Astronomy and Astrophysics.
In a follow-up study, scientists went a step further, using the brightness and age of the planet — dubbed PDS 70b — to derive its mass. “Mass is the main indicator that it’s a planet,” says the study’s co-author Sascha Quanz (ETH Zürich, Switzerland); indeed, PDS 70b turned out to be between 2 to 17 times Jupiter's mass, which qualifies it as a planet rather than a brown dwarf. It’s made mostly of gas and has a temperature of about 1000°C.
By analyzing the planet’s spectrum, scientists discovered that the planet’s atmosphere even contains clouds. “Clouds have a different meaning than on Earth,” warns Müller; this planet’s extreme temperatures don’t allow for water condensation. Instead, its clouds contain ingredients such as iron, sodium sulfite, potassium chloride, and even a magnesium compound called fosterite.
In addition to using new observations, scientists also revisited observations dating back to 2012 in order to track the planet’s location. While doing this, they saw an arc in the protoplanetary disk that was indicative of orbital motion. The team concluded that it takes PDS 70b about 120 years to orbit its star.
The planet is still forming by accumulating material, adds André Müller (MPIA), the second study’s leader author. The present findings “confirm theoretical models, but we need more of these systems to understand the process,” he says.
Trent Dupuy (Gemini Observatory), who was not involved in the study, warns of the “technological challenges of confirming very faint objects next to very bright stars,” which make it difficult to confirm that any point source is a new planet. But he adds: “Overall, I think this extremely exciting.” | <urn:uuid:34487e4f-603c-4923-bd99-d4b076eac3f9> | 3.890625 | 678 | News Article | Science & Tech. | 52.853747 | 95,533,747 |
STORMS have clouded Uranus’s normally placid face. In the past year, the gas planet has played host to huge cloud systems so bright that even amateur astronomers can see them from Earth – and their cause is a mystery.
“We have no idea. It’s very unexpected,” says Imke de Pater at the University of California, Berkeley.
De Pater observed Uranus on 5 and 6 August, 2014, and was surprised to spot unusually bright features, the hallmark of clouds condensing in the planet’s upper atmosphere. “It was brighter than anything we had ever seen in Uranus’s atmosphere before,” she says. The planet’s weather generally picks up at its spring and autumn equinoxes every 42 years, when the sun shines on the equator. But the last equinox was 7 years ago, so the recent spike in activity is difficult to explain.
De Pater’s group spread the word, and amateurs around the globe trained their telescopes on Uranus. Coincidentally, the amateurs spotted a storm that de Pater had imaged at a different wavelength on 5 August. Using the Hubble Space Telescope, de Pater and her colleagues saw storms spanning a variety of altitudes (arxiv.org/abs/1501.01309), which could be linked to a vortex deep in Uranus’s atmosphere. | <urn:uuid:604547fa-3939-4007-9432-3dde4b87daa1> | 3.890625 | 299 | News Article | Science & Tech. | 54.603447 | 95,533,748 |
x Solar wind is a stream of charged particles continually blown outward in all
directions from the Sun.
x It helps shape the magnetosphere of planets and blows back the material that forms
the plasma tails of comets. It also cleared away the gas of the solar nebula.
x The corona LVWKHRXWHUPRVWOD\HURIWKHVXQ¶VDWPRVSKHUH,WVWHPSHUDWXUHEHing 1
density is extremely low.
x The chromospehere is the middle layer of the solar atmosphere and the region that
UDGLDWHVPRVWRIWKH6XQ¶VXOWUDYLROHWZLWKDWHPSHUDWXUHRI about 10,000 K.
x The photosphere is the lowest layer of the atmosphere, which is the visible surface
of the Sun. Its temperature is about 6,000 K and it is where sunspots are found.
x The convection zone is where energy generated in the solar core travels upward,
transported by the rising of hot gas and falling of cool gas, a process called
x The radiation zone is where energy moves outward primarily in the form of
photons of light. The temperature is about 10 million K with predominant X rays.
x The solar core is where nuclear fusion transforms hydrogen into helium. The
temperature is about 15 million K with 100X the density of water and pressure that
is 200-billionX that on the surface of Earth.
The Cosmic Crucible
x Nuclear Fission ± the process of splitting a nucleus into two smaller nuclei.
x Nuclear Fusion ± the process of combining nuclei to make a nucleus with a greater
number of protons or neutrons.
x Human-built nuclear power plants rely on nuclear fission of uranium or plutonium.
x The nuclear power plant of the Sun relies on nuclear fusion, turning hydrogen to
Nuclear Fusion in the Sun
x Fusion occurs within the Sun, because of positively charged atomic nuclei in the
solar core moving at high speeds, colliding with one another.
x In most cases, electromagnetic forces deflect the nuclei, preventing collisions,
because positive charges repel one another.
x A collision with sufficient energy will stick together to form a heavier nucleus.
x Sticking positively charged nuclei require strong force (can overcome positive
repulsion), which binds protons and neutrons together in atomic nuclei.
x The strong is like glue/Velcro ± overpowers the electromagnetic force over very
x Nuclear fusion is to push the positively charged nuclei close enough together for
the strong force to outmuscle electromagnetic repulsion. | <urn:uuid:8f3d7292-b5f3-42af-98e3-cd6f367db346> | 3.671875 | 569 | Content Listing | Science & Tech. | 43.849425 | 95,533,762 |
The Applied Synthon Model
In the preceding chapter we have defined the notion of a synthon. Its main difference from the molecular graph (Chap. 2) is that some of its vertices are distinguished from others by virtue of being so-called virtual vertices. In our forthcoming considerations we shall often use the term atom instead of the mathematical term vertex. The virtual vertex, or atom, represents a “virtual” functional group or a molecular fragment irrelevant for the chemical transformations of interest. Let us consider a synthon constructed over an atomic set A, this synthon is chemically described by a structural formula in which some bonds are not terminated by atoms. Loosely speaking, they are sticking out of the structural formula and formally terminate in virtual atoms. A synthon constructed over the atomic set A will be denoted by the symbol S (A).
KeywordsValence State Structural Formula Triple Bond Internal Component External Component
Unable to display preview. Download preview PDF.
References (Chapter 4)
- 1.Koča J (1989) J. Math. Chem. (in press)Google Scholar
- 2.Koča J (1989) Coll. Czech. Chem. Commun. (in press)Google Scholar
- 3.Dugundji J, Ugi I (1973) Top. Curr. Chem. 39:19Google Scholar
- 7.Kratochvíl M, Koča J (1985) Chemistry in graphs (in Czech), Lachema, BrnoGoogle Scholar
- 9.Kratochvíl M, Koča J, Kvasnička V (1985) Chem. Listy (in Czech) 79:807Google Scholar | <urn:uuid:a2433879-17e8-4aa3-a180-aceccff8df38> | 2.65625 | 356 | Academic Writing | Science & Tech. | 58.384874 | 95,533,776 |
Explaining the history of Australia’s vegetation
University of Adelaide-led research has uncovered the history of when and why the native vegetation that today dominates much of Australia first expanded across the continent.
The new understanding will help researchers better predict the likely impact of climate change and rising CO2 levels on these critically important plants. Called 'C4 plants' after their alternative photosynthetic pathway, these plants include a wide variety of native tropical, subtropical and arid grasses as well as saltbushes. C4 crops include sugarcane and corn.
"C4 plants evolved to be able to photosynthesise under warm, dry, and low CO2 conditions, with a special ability to take advantage of summer rainfall," says lead author Jake Andrae, PhD candidate in the University's School of Physical Sciences and Sprigg Geobiology Centre. "As a result, they dominate the vegetation of Australian tropical, subtropical, and arid regions today.
"But despite being the most C4 dominated continent today, little is known about the initial C4 expansion in Australia."
The researchers analysed fossilised leaf waxes and pollen preserved in marine sediments. They measured the chemical signatures from these remnants, to reconstruct how and when C4-dominated ecosystems first rose to prominence in Australia.
"In many regions around the globe, C4 plants became prevalent between six and eight million years ago, which is thought by some to be the result of falling global atmospheric CO2 concentrations during this time," says project leader Dr Francesca McInerney, Australian Research Council Future Fellow at the University of Adelaide.
"Surprisingly, in north-west Australia C4 plants did not expand at this time in spite of regionally arid conditions and falling atmospheric CO2, both of which should have promoted C4 vegetation. Instead, C4 vegetation expanded across the landscape only 3.5 million years ago, several million years later."
The authors say that the rise of C4 plants in Australia was likely the result of a strong summer monsoon that developed around that time.
"The difference in the timing of the expansion of C4 plants in Australia from other parts of the globe demonstrates that regional climate changes are important in driving vegetation change," Dr McInerney says.
"In the future, the interaction between global atmospheric CO2 and regional changes in seasonality of rainfall is likely to play an important role in the distribution of C4-dominated ecosystems. Rising CO2 will place C4 plants at a disadvantage, while rising temperatures, and changes in the season and amount of rainfall, could favour them.
"In Australia, C4 plants are critical to grazing, soil carbon storage and biodiversity. We need to understand the factors that are likely to influence their survival in the future, to provide a basis for future conservation of these important plants."
The research, in collaboration with Columbia University and University of Melbourne, has been published online in Geophysical Research Letters.
Dr Francesca McInerney, ARC Future Fellow, School of Physical Sciences, University of Adelaide. Phone: +61 (0) 8 8313 0228, Mobile: +61 (0)427 032 681, [email protected]
Mr Jake Andrae, PhD candidate, School of Physical Sciences, University of Adelaide. Phone: +61 (0) 407 701 565, [email protected]
Robyn Mills, Media Officer, University of Adelaide. Phone: +61 (0)8 8313 6341, Mobile: +61 (0)410 689 084, [email protected]
Related Journal Article | <urn:uuid:364b1dc1-ad5a-4820-adbd-edbdc3456150> | 3.765625 | 740 | Truncated | Science & Tech. | 27.677995 | 95,533,788 |
Weizmann Institute of Science..
(photo credit: MICHAEL JACOBSON/WIKIMEDIA COMMONS)
Researchers from the Weizmann Institute of Science and Tel Aviv University have discovered for the first time how the immune system in bacteria manages to recognize the difference between “foreign” and “self” and fight off invasive viruses called phages.
From single cells to humans, the first challenge of any immune system is to detect this key difference, but it’s far from simple – as viruses, bacteria and all other living things are made of DNA and proteins. Their findings were published online recently in the prestigious journal Nature.
“In most environments, phages are around 10 times more abundant than bacteria, and like all viruses, phages use the host cell’s replication machinery to make copies of themselves,” said Prof.
Rotem Sorek of Weizmann’s molecular genetics department. “They are constantly evolving new ways to do this, so bacteria need a very active immune system to survive.”
But until recently, scientists were not even sure that bacteria had a so-called adaptive immune system – one that “remembers” a past encounter to produce a targeted response. That changed several years ago when a bacterial adaptive system called CRISPR was discovered. The CRISPR immune mechanism is crucial not only to bacteria, but it has a major impact on daily human lives, as it is used to protect the “good” bacteria that make yogurt and cheese. It may also affect our future, as scientists have figured out how to use the ingenious CRISPR system to “edit” the human genome – making it a handy tool for a wide range of clinical applications.
To remember an infection, the CRISPR system grabs a short sequence from the invading viral DNA and inserts it straight into the bacterial genome. The bits of phage DNA are stored in special sections of the genome; these form the immune memory. In subsequent infections, CRISPR uses these sequences to create short strands of RNA that fit the genetic sequence of the phages’ kin. Protein complexes attached to the RNA then identify the phage DNA and destroy it.
Previous research in Sorek’s lab had shown that mistakenly grabbing bits of self-DNA can cause the bacterial cell to suffer a sort of autoimmune disease in which it attacks its own DNA, possibly with fatal results for the bacteria. With around 100 times more native than foreign DNA in the cell, noted Sorek, there would seem to be room for many more mistakes than researchers have actually observed.
How does the CRISPR system know how to insert foreign rather than native bits of DNA into the immune memory? Sorek and his research student Asaf Levy teamed up with TAU Prof. Udi Qimron and Moran Goren to find out.
They devised an experimental setup using plasmids – short, circular pieces of DNA that mimic viruses – and injected them into bacteria cells. These bacteria had two proteins known as Cas1 and Cas2 – parts of the CRISPR system that are responsible for acquiring the pieces of foreign DNA. The CRISPR system successfully incorporated the plasmid DNA into the bacterial genome, while the native DNA was only rarely attacked. The team recorded some 38 million separate immunization events.
With this, they found that the CRISPR system, using the proteins Cas 1 and 2, specifically identifies DNA that replicates rapidly. Thus, ironically, it is the phage’s survival tactic – its programmed drive to replicate at all costs – that proves to be its downfall.
“Solving the riddle of self versus nonself for the bacterial immune system and deciphering the exact mechanism of this step in the CRISPR process gives us important insight into the unseen confrontation that is taking place everywhere, all around us, all the time,” concluded Sorek. | <urn:uuid:2fb7ed0a-eda0-494e-838d-5558e919cc62> | 3.25 | 818 | News Article | Science & Tech. | 36.107074 | 95,533,790 |
Unprecedented study describes sources contributing to decline of Caribbean reefs
Their position at the pinnacle of the marine food chain is legendary. Now, understanding sharks and their significance as top predators-and the consequences of human activity towards them-has taken on new importance through a new study by scientists in San Diego and Spain.
Jordi Bascompte and Carlos Melián of the Integrative Ecology Group, Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas, in Sevilla, Spain, and Enric Sala of Scripps Institution of Oceanography at the University of California, San Diego, developed an unprecedented model of a Caribbean marine ecosystem and details of its intricate predator-prey interactions. This food "web" covered 1,000 square kilometers to a depth of 100 meters and included some 250 species of marine organisms. The study, published in the April 12 edition of the Proceedings of the National Academy of Sciences, included an intricate network of more than 3,000 links between these species. The project was one of the largest and most detailed investigations of marine food webs and the first study to integrate food web structure, dynamics and conservation.
Mario Aguilera | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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Distribution of two species of the genus Nototanais spp. (Tanaidacea) in Winter Quarters Bay and waters adjoining McMurdo Station, McMurdo Sound, Antarctica
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Nototanais is the most commonly found peracarid crustacean genus in Antarctic waters. The only two species in the genus, Nototanais dimorphus and Nototanais antarcticus, have been found to have overlapping circumpolar distributions in depths from 7 m to 585 m around Antarctica. However, only one species, N. dimorphus, has been recorded during yearly sampling from 2000 to 2010 at nine shallow (12–36 m) benthic pollution monitoring sites in Winter Quarters Bay and waters adjoining McMurdo Station, McMurdo Sound, Antarctica. These stations varied by depth, anchor ice formation and anthropogenic contamination. In 2011 and 2012, 1071 specimens of Nototanais spp. were collected and separated by species, gender and life stage. N. antarcticus was confirmed to co-occur with N. dimorphus at four of nine long-term monitoring sites. One station had no occurrences of either species. N. antarcticus was found in very low abundances in relation to N. dimorphus, indicating that individual species distributions may be modified by pollution and anchor ice, among other biological factors.
KeywordsNototanais Tanaids Pollution McMurdo Sound Antarctica Peracarid Winter Quarters Bay McMurdo Station
The authors would like to thank McMurdo Station support staff including divers Rob Robbins, Steve Rupp, Brenda Konar and Terril Efird. The authors would also like to thank other field workers Andrew Klein (Co-PI), Steve Sweet, Joni Kincaid, Michelle Brown and Daniel Russell and the Principal Investigator of the McMurdo environmental monitoring project Mahlon C. Kennicutt II. Cliff Pereira at Oregon State University Statistics Department provided an extensive review of the statistical methods used in the final analysis. This research is supported by the Harte Research Institute at Texas A&M University-Corpus Christi and Department of Defense, Army Corp of Engineers Cold Regions Research & Engineering Laboratory Contract Number: W913E5-12-C-0006 via subcontract S120048 from the Texas A&M Research Foundation.
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The study featured on the cover of the November issue of Ecology shows animal bone remains provide high-quality geographical data across an extensive time frame. The research may be used to identify regions of habitat for the conservation of threatened species.
Charles Darwin first noted the importance of studying where animal bones lie on the landscape in 1860, but the topic has since become largely lost to scientists trying to protect and conserve native wildlife. By documenting accumulations of elk bones and antlers on the landscape of Yellowstone National Park in Wyoming, study author Joshua Miller identified areas critical for the species’ survival during spring and winter.
“This is fundamental stuff, because for a long time the common knowledge was that bones only lasted a few years on the landscape,” said Miller, an assistant scientist at the Florida Museum of Natural History on the UF campus and Fenneman assistant research professor at the University of Cincinnati. “It turns out they last a lot longer and surveys of bones on landscapes offer a new tool for conservation and management – one that allows us to collect decades of biological data in a single field season.”
Walking across Yellowstone Park, Miller documented elk skeletal remains and determined the bones record the same seasonal distributions as aerial surveys of living elk.
Ecologists typically gather information for conservation by monitoring wild animals, a task requiring years of financial support and countless hours of observation by wildlife biologists. A long-term study in ecology consists of at least 10 to 20 years of census data. However, because some bones can survive on some landscapes for hundreds of years, they may include data from time periods beyond the reaches of a traditional ecological study, including historical insight often missing from scientists’ knowledge of ecosystems, Miller said.
“A major challenge for wildlife conservation and management has been that biologists can only work in the present – researchers can only start from when they began collecting data,” Miller said. “If someone wants to develop a piece of land, for example, there may only be time for a few years of data collection, and we know as ecologists that such limited observations aren’t enough to capture the full complexities of an ecosystem. This research shows we can go into the past, essentially using bones to travel through time and learn about generations of wildlife that were previously lost to science.”
A popular hunting species, male elk grow to 700 pounds, shedding their more than 30-pound antlers annually. Miller used standardized bone surveys on 40 five-eighth-mile-long plots in the northern range of Yellowstone Park to identify wintering grounds by antler accumulations and calving grounds by the appearance of newborn skeletons.
“Bones are not randomly scattered across a landscape,” Miller said. “Where a bone is found is often as biologically informative as which species it’s from. As we investigate the quality of these geographic data, we’re discovering that this is a gold mine of information.”
Although the study represents a narrow test case, the strong correlation between how bones are distributed across Yellowstone Park and known patterns in how elk use the landscape shows this low-impact survey technique may be useful for understanding other areas, including poorly known or fragile ecosystems, Miller said.
Anna Behrensmeyer, vertebrate paleontology curator at the Smithsonian Institution’s National Museum of Natural History, uses bone surveys in East Africa for understanding the area’s mammal populations and how bones become part of the fossil record. She said the study of taphonomy, the processes affecting organic remains as they become fossilized, is not commonly recognized in the field of ecology.
“In my long-term studies of bones, it has struck me that many ecologists have been missing useful information that is available in bones lying about on modern landscapes,” Behrensmeyer said. “Josh is showing the potential of using bones, antlers and other remains to monitor what animals have been doing for the past decades and even hundreds of years.”
Behrensmeyer said she hopes taphonomy as a research tool spreads from its traditional place in paleontology and archaeology into the realm of ecology.
“Sometimes we taphonomists feel like a small voice in the universe – it’s hard for the dead to capture the attention of scientists focused on understanding living organisms and ecosystems,” Behrensmeyer said. “Once ecologists see this study, they could very well say, ‘Why didn’t I think of that?’ ”Writer:
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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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NASA's Aqua and Terra satellites captured before and after images of Bermuda and surrounding waters before and after Hurricane Gonzalo struck the island on Oct. 17. The images revealed how Gonzalo stirred up the sediment from the ocean bottom.
The MODIS instrument or Moderate Resolution Imaging Spectroradiometer that flies aboard NASA's Aqua and Terra satellites provided imagery of Bermuda and the stirred sediment.
In a comparison of imagery before and after Hurricane Gonzalo passed, the after image showed sediment streaming east and south of Bermuda.
The MODIS instrument aboard NASA's Aqua satellite captured a "before" look of Bermuda on Oct. 4 at 17:20 UTC (1:20 p.m. EDT). The MODIS instrument aboard NASA's Terra satellite captured the "after" image from Oct. 19 at 15:00 UTC (11 a.m. EDT).
Whenever a hurricane moves over an area, it stirs up sediment from the ocean bottom. In more shallow areas the mixing of sediment to the surface is more visible on satellite imagery.
Around Bermuda, the ocean is shallow. There are coral reefs and banks that can be seen under the surface when waters are clear. Bermuda's coral reefs are some of the northern-most reefs in the North Atlantic.
In the MODIS images a lighter blue area traces the outline of the shallow waters around the reef. The deeper water around it appears dark blue.
Run off of sand dirt from the island fans out in tan and light green plumes. The extra nutrients that the run-off and bottom sediment bring to the surface may be feeding surface-dwelling ocean plants, which may also color ocean waters turquoise.
As the sediment settles around Bermuda, the United Kingdom was dealing with post-tropical cyclone Gonzalo's remnants.
Gonzalo's remnants were bringing heavy rains and gusty winds to much of the United Kingdom on Tuesday, Oct. 21. The U.K. Meteorological Service forecast wind gusts between 40 and 50 mph. In some coastal areas, winds could reach 60 to 70 mph. For updated forecasts from the U.K. Met Service, visit: http://www.metoffice.gov.uk.
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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.
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public interface WordReader extends java.io.Serializable
This interface is heavily oriented towards reusability and streaming. It is conceived so that at most one method call has to be performed per word, rather than per character, and that implementations may completely avoid object creation by setting explicitly the underlying reader.
The standard implementation (
words in the trivial way. More complex implementations (e.g., for languages requiring
segmentation) can subclass
FastBufferedReader or provide their
|Modifier and Type||Method||Description|
Returns a copy of this word reader.
Extracts the next word and non-word.
Resets the internal state of this word reader, which will start again reading from the given reader.
boolean next(MutableString word, MutableString nonWord) throws java.io.IOException
If this method returns true, a new non-empty word, and possibly
a new non-word, have been extracted. It is acceptable
that the first call to this method after creation
or after a call to
setReader(Reader) returns an empty
word. In other words both
nonWord are maximal.
word- the next word returned by the underlying reader.
nonWord- the nonword following the next word returned by the underlying reader.
WordReader setReader(java.io.Reader reader)
reader- the new reader providing characters.
This method must return a word reader with a behaviour that matches exactly that of this word reader. | <urn:uuid:720cd61b-37dc-475d-8577-5feb5b2a3fc6> | 2.546875 | 314 | Documentation | Software Dev. | 46.75137 | 95,533,884 |
A View from Emerging Technology from the arXiv
Death Test Reveals Strength of Social Interaction
Social ties between humans are stronger than those between fruit flies or ants but weaker than those between bees, according to a cheerful new ranking based on how quickly creatures die when they become isolated
Back in 1993, a team of cell biologists carried out an unusual experiment. These guys measured how the lifespans of cells changed depending on the density of other cells around them.
It turns out that isolated cells die the quickest. They concluded that cells always die unless they get repeated signals from other cells nearby saying “stay alive, stay alive”.
The research has never been followed up and the mechanism at work remains a mystery. But it leaves open a number of interesting questions. Not least of these is whether isolation can also affect the lifespan of other creatures.
Today, Lei Wang at the Red Imported Fire Ants Research Center in Guangzhou, China and a few pals investigate this idea for ants and fruit flies and compare their data with mortality rates for humans who themselves have become isolated.
And their conclusion is startling. They say they can easily measure the reduction in lifespan for isolated ants and fruit flies but they also go further. They say this effect is a measure of the strength of social ties within that species, since creatures with weak social ties are unlikely to be affected much by isolation while those with strong social ties likely to be severely affected.
The experiments are time-consuming but straightforward. These guys took fire ants from a colony in their lab and put them in bowls either individually or in groups of 10. They then waited to see how quickly the ants died and compared this to the average lifespan of ants in the colony.
It turns out that individually isolated ants die quickest, followed by ants in a group of 10 with ants in the colony living the longest at an average of 62 days each. (The experiments took two years in total).
They performed similar experiments with similar results on fruit flies.
Finally, Lei and co compared the results to the mortality data for humans who become isolated when their partner dies. It has long been known that widows or widowers are much more likely to die than those who are married.
However, they point out that this effect is much stronger for younger people than for older people. Lei and co say this is because the social ties between young people, who are generally more recently married, are much stronger than those between people who have been married for a long period of time.
They also threw in the results from a similar experiment done on bees in 1944.
This has allowed Lei and co to rank species according to the strength of their social ties.
They say the fruit flies have the weakest ties, followed by ants, men over the age of 50, men under the age of 50, followed by bees and finally cells, which have the strongest ties.
So the social ties in humans are stronger than those in ants and in fruit flies but weaker than those in bees and in cells.
However, Lei and co are quick to point out that they propose this ranking as a conjecture to stimulate further research.
That’s a curious result that comes from an unusual collaboration between physicists and entomologists.
We’ve looked at previous work from this team in measuring the strength of interaction between creatures using physics-based experiments.
Previous work in this area of social interaction has been Spartan. So it’ll be interesting to see whether this new approach can galvanise others to build on the work.
Ref: arxiv.org/abs/1304.2935: How Does Group Interaction And Its Severance Affect Life Expectancy?
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Photosynthesis sustains most of the life on our planet. It harvests energy from sunlight, while generating oxygen and removing carbon dioxide from the atmosphere. The process takes place in the chloroplasts of plants and algae. Researchers in the team of Wolfgang Baumeister at the Max Planck Institute of Biochemistry in Martinsried near Munich were recently successful in revealing the native structure of the chloroplast in 3D.
“The results are the first of their kind and provide us with new insights into the mechanisms of photosynthesis”, says Benjamin Engel, first author of the study. The results were recently published in the journal eLife.
So far, researchers who wanted to observe tiny structures inside of cells had to use traditional electron microscopy. However, this method requires several preparation steps that damage cellular structures and limit the resolution and accuracy of the images. By using cryo-electron tomography, Wolfgang Baumeister and his team are able to avoid these steps by rapidly freezing the cells. Moreover, this allows them to visualize the internal architecture of cells in a close-to-living state. Using this technique, the scientists investigated the three dimensional structures of chloroplasts in the alga Chlamydomonas, shedding new light on their assembly and function.
Two spatially separated reactions take place during photosynthesis: while energy is harvested from sunlight in compartments called the thylakoids, carbon dioxide is fixed to form sugar molecules in a compartment called the pyrenoid. It was not understood how these processes could be coordinated. The new 3D images revealed the detailed structures of tubules that connect the pyrenoid with the thylakoids, providing conduits for the diffusion of energy molecules and sugars between these two separated parts of the chloroplast (see figure).
Besides the fact that there are connections between the two reaction compartments, the scientists were also able to show how the thylakoids receive new proteins and how the photosynthesis enzymes are organized: “In the pyrenoid, there are many units of the photosynthesis enzyme RuBisCO”, explains Benjamin Engel, scientist at the MPI of Biochemistry. “Our results show for the first time that these units are packed in a hexagonal arrangement.” In the future, the authors aim to elucidate how this RuBisCO organization is formed and whether more proteins are involved. [HS]
Engel B, Schaffer M, Kuhn Cuellar L, Villa E, Plitzko JM and Baumeister W: Native Architecture of the Chlamydomonas Chloroplast Revealed by In Situ Cryo-Electron Tomography. eLife, January 13, 2015.
Prof. Dr. Wolfgang Baumeister
Molecular Structural Biology
Max Planck Institute of Biochemistry
Am Klopferspitz 18
Max Planck Institute of Biochemistry
Am Klopferspitz 18
Phone: +49 89 8578-2824
http://www.biochem.mpg.de/baumeister - Website of the Research Department "Molecular Structural Biology" (Prof. Dr. Wolfgang Baumeister)
http://www.biochem.mpg.de/news - More press releases of the MPI of Biochemistry
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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The storage of plutonium has long plagued scientists. “It is a dangerous metal and its long term storage must be done with special care so as not to harm the environment, ”said physicist Serguei Savrasov, Ph.D.
Finding a solution to this problem led Savrasov, an associate professor at New Jersey Institute of Technology (NJIT), and a team of researchers at Rutgers University and Los Alamos National Laboratories, to study how this metal reacts to heat, a natural condition of storage over time.
The team’s findings are published in the May 9, 2003 issue of Science.
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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Length contraction is the phenomenon that a moving object's length is measured to be shorter than its proper length, which is the length as measured in the object's own rest frame. This contraction (more formally called Lorentz contraction or Lorentz-FitzGerald contraction after Hendrik Lorentz and George Francis FitzGerald) is usually only noticeable at a substantial fraction of the speed of light. Length contraction is only in the direction in which the body is travelling. For standard objects, this effect is negligible at everyday speeds, and can be ignored for all regular purposes, only becoming significant as the object approaches the speed of light relative to the observer.
Length contraction was postulated by George FitzGerald (1889) and Hendrik Antoon Lorentz (1892) to explain the negative outcome of the Michelson-Morley experiment and to rescue the hypothesis of the stationary aether (Lorentz-FitzGerald contraction hypothesis). Although both FitzGerald and Lorentz alluded to the fact that electrostatic fields in motion were deformed ("Heaviside-Ellipsoid" after Oliver Heaviside, who derived this deformation from electromagnetic theory in 1888), it was considered an ad hoc hypothesis, because at this time there was no sufficient reason to assume that intermolecular forces behave the same way as electromagnetic ones. In 1897 Joseph Larmor developed a model in which all forces are considered to be of electromagnetic origin, and length contraction appeared to be a direct consequence of this model. Yet it was shown by Henri Poincaré (1905) that electromagnetic forces alone cannot explain the electron's stability. So he had to introduce another ad hoc hypothesis: non-electric binding forces (Poincaré stresses) that ensure the electron's stability, give a dynamical explanation for length contraction, and thus hide the motion of the stationary aether.
Eventually, Albert Einstein (1905) was the first to completely remove the ad hoc character from the contraction hypothesis, by demonstrating that this contraction did not require motion through a supposed aether, but could be explained using special relativity, which changed our notions of space, time, and simultaneity. Einstein's view was further elaborated by Hermann Minkowski, who demonstrated the geometrical interpretation of all relativistic effects by introducing his concept of four-dimensional spacetime.
First it is necessary to carefully consider the methods for measuring the lengths of resting and moving objects. Here, "object" simply means a distance with endpoints that are always mutually at rest, i.e., that are at rest in the same inertial frame of reference. If the relative velocity between an observer (or his measuring instruments) and the observed object is zero, then the proper length of the object can simply be determined by directly superposing a measuring rod. However, if the relative velocity > 0, then one can proceed as follows:
The observer installs a row of clocks that either are synchronized a) by exchanging light signals according to the Poincaré-Einstein synchronization, or b) by "slow clock transport", that is, one clock is transported along the row of clocks in the limit of vanishing transport velocity. Now, when the synchronization process is finished, the object is moved along the clock row and every clock stores the exact time when the left or the right end of the object passes by. After that, the observer only has to look at the position of a clock A that stored the time when the left end of the object was passing by, and a clock B at which the right end of the object was passing by at the same time. It's clear that distance AB is equal to length of the moving object. Using this method, the definition of simultaneity is crucial for measuring the length of moving objects.
Another method is to use a clock indicating its proper time , which is traveling from one endpoint of the rod to the other in time as measured by clocks in the rod's rest frame. The length of the rod can be computed by multiplying its travel time by its velocity, thus in the rod's rest frame or in the clock's rest frame.
In Newtonian mechanics, simultaneity and time duration are absolute and therefore both methods lead to the equality of and . Yet in relativity theory the constancy of light velocity in all inertial frames in connection with relativity of simultaneity and time dilation destroys this equality. In the first method an observer in one frame claims to have measured the object's endpoints simultaneously, but the observers in all other inertial frames will argue that the object's endpoints were not measured simultaneously. In the second method, times and are not equal due to time dilation, resulting in different lengths too.
The deviation between the measurements in all inertial frames is given by the formulas for Lorentz transformation and time dilation (see Derivation). It turns out that the proper length remains unchanged and always denotes the greatest length of an object, and the length of the same object measured in another inertial reference frame is shorter than the proper length. This contraction only occurs along the line of motion, and can be represented by the relation
Replacing the Lorentz factor in the original formula leads to the relation
In this equation both L and L0 are measured parallel to the object's line of movement. For the observer in relative movement, the length of the object is measured by subtracting the simultaneously measured distances of both ends of the object. For more general conversions, see the Lorentz transformations. An observer at rest observing an object travelling very close to the speed of light would observe the length of the object in the direction of motion as very near zero.
Then, at a speed of 13,400,000 m/s (30 million mph, 0.0447c) contracted length is 99.9% of the length at rest; at a speed of 42,300,000 m/s (95 million mph, 0.141c), the length is still 99%. As the magnitude of the velocity approaches the speed of light, the effect becomes prominent.
The principle of relativity (according to which the laws of nature must assume the same form in all inertial reference frames) requires that length contraction is symmetrical: If a rod rests in inertial frame S, it has its proper length in S and its length is contracted in S'. However, if a rod rests in S', it has its proper length in S' and its length is contracted in S. This can be vividly illustrated using symmetric Minkowski diagrams (or Loedel diagrams), because the Lorentz transformation geometrically corresponds to a rotation in four-dimensional spacetime.
Magnetic forces are caused by relativistic contraction when electrons are moving relative to atomic nuclei. The magnetic force on a moving charge next to a current-carrying wire is a result of relativistic motion between electrons and protons.
In 1820, André-Marie Ampère showed that parallel wires having currents in the same direction attract one another. To the electrons, the wire contracts slightly, causing the protons of the opposite wire to be locally denser. As the electrons in the opposite wire are moving as well, they do not contract (as much). This results in an apparent local imbalance between electrons and protons; the moving electrons in one wire are attracted to the extra protons in the other. The reverse can also be considered. To the static proton's frame of reference, the electrons are moving and contracted, resulting in the same imbalance. The electron drift velocity is relatively very slow, on the order of a meter an hour but the force between an electron and proton is so enormous that even at this very slow speed the relativistic contraction causes significant effects.
Any observer co-moving with the observed object cannot measure the object's contraction, because he can judge himself and the object as at rest in the same inertial frame in accordance with the principle of relativity (as it was demonstrated by the Trouton-Rankine experiment). So length contraction cannot be measured in the object's rest frame, but only in a frame in which the observed object is in motion. In addition, even in such a non-co-moving frame, direct experimental confirmations of length contraction are hard to achieve, because at the current state of technology, objects of considerable extension cannot be accelerated to relativistic speeds. And the only objects traveling with the speed required are atomic particles, yet whose spatial extensions are too small to allow a direct measurement of contraction.
However, there are indirect confirmations of this effect in a non-co-moving frame:
The author unjustifiably stated a difference of Lorentz's view and that of mine concerning the physical facts. The question as to whether length contraction really exists or not is misleading. It doesn't "really" exist, in so far as it doesn't exist for a comoving observer; though it "really" exists, i.e. in such a way that it could be demonstrated in principle by physical means by a non-comoving observer.-- Albert Einstein, 1911
Einstein also argued in that paper, that length contraction is not simply the product of arbitrary definitions concerning the way clock regulations and length measurements are performed. He presented the following thought experiment: Let A'B' and A"B" be the endpoints of two rods of the same proper length L0, as measured on x' and x" respectively. Let them move in opposite directions along the x* axis, considered at rest, at the same speed with respect to it. Endpoints A'A" then meet at point A*, and B'B" meet at point B*. Einstein pointed out that length A*B* is shorter than A'B' or A"B", which can also be demonstrated by bringing one of the rods to rest with respect to that axis.
Due to superficial application of the contraction formula some paradoxes can occur. Examples are the ladder paradox and Bell's spaceship paradox. However, those paradoxes can simply be solved by a correct application of relativity of simultaneity. Another famous paradox is the Ehrenfest paradox, which proves that the concept of rigid bodies is not compatible with relativity, reducing the applicability of Born rigidity, and showing that for a co-rotating observer the geometry is in fact non-euclidean.
Length contraction refers to measurements of position made at simultaneous times according to a coordinate system. This could suggest that if one could take a picture of a fast moving object, that the image would show the object contracted in the direction of motion. However, such visual effects are completely different measurements, as such a photograph is taken from a distance, while length contraction can only directly be measured at the exact location of the object's endpoints. It was shown by several authors such as Roger Penrose and James Terrell that moving objects generally do not appear length contracted on a photograph. For instance, for a small angular diameter, a moving sphere remains circular and is rotated. This kind of visual rotation effect is called Penrose-Terrell rotation.
Length contraction can be derived from the Lorentz transformation in several ways:
In an inertial reference frame S, and shall denote the endpoints of an object in motion in this frame. There, its length was measured according to the above convention by determining the simultaneous positions of its endpoints at . Now, the proper length of this object in S' shall be calculated by using the Lorentz transformation. Transforming the time coordinates from S into S' results in different times, but this is not problematic, as the object is at rest in S' where it does not matter when the endpoints are measured. Therefore, the transformation of the spatial coordinates suffices, which gives:
Since , and by setting and , the proper length in S' is given by
with respect to which the measured length in S is contracted by
According to the relativity principle, objects that are at rest in S have to be contracted in S' as well. By exchanging the above signs and primes symmetrically, it follows:
Thus the contracted length as measured in S' is given by:
Conversely, if the object rests in S and its proper length is known, the simultaneity of the measurements at the object's endpoints has to be considered in another frame S', as the object constantly changes its position there. Therefore, both spatial and temporal coordinates must be transformed:
With and this results in non-simultaneous differences:
In order to obtain the simultaneous positions of both endpoints, the second endpoint must be advanced by with the speed of S relative to S'. To obtain the length , the quantity must therefore be added to :
So the moving length in S' is contracted. Likewise, the preceding calculation gives a symmetric result for an object at rest in S':
Length contraction can also be derived from time dilation, according to which the rate of a single "moving" clock (indicating its proper time ) is lower with respect to two synchronized "resting" clocks (indicating ). Time dilation was experimentally confirmed multiple times, and is represented by the relation:
Suppose a rod of proper length at rest in and a clock at rest in are moving along each other with speed . Since, according to the principle of relativity, the magnitude of relative velocity is the same in either reference frame, the respective travel times of the clock between the rod's endpoints are given by in and in , thus and . By inserting the time dilation formula, the ratio between those lengths is:
Therefore, the length measured in is given by
So since the clock's travel time across the rod is longer in than in (time dilation in ), the rod's length is also longer in than in (length contraction in ). Likewise, if the clock were at rest in and the rod in , the above procedure would give
Additional geometrical considerations show, that length contraction can be regarded as a trigonometric phenomenon, with analogy to parallel slices through a cuboid before and after a rotation in E3 (see left half figure at the right). This is the Euclidean analog of boosting a cuboid in E1,2. In the latter case, however, we can interpret the boosted cuboid as the world slab of a moving plate.
Image: Left: a rotated cuboid in three-dimensional euclidean space E3. The cross section is longer in the direction of the rotation than it was before the rotation. Right: the world slab of a moving thin plate in Minkowski spacetime (with one spatial dimension suppressed) E1,2, which is a boosted cuboid. The cross section is thinner in the direction of the boost than it was before the boost. In both cases, the transverse directions are unaffected and the three planes meeting at each corner of the cuboids are mutually orthogonal (in the sense of E1,2 at right, and in the sense of E3 at left).
In special relativity, Poincaré transformations are a class of affine transformations which can be characterized as the transformations between alternative Cartesian coordinate charts on Minkowski spacetime corresponding to alternative states of inertial motion (and different choices of an origin). Lorentz transformations are Poincaré transformations which are linear transformations (preserve the origin). Lorentz transformations play the same role in Minkowski geometry (the Lorentz group forms the isotropy group of the self-isometries of the spacetime) which are played by rotations in euclidean geometry. Indeed, special relativity largely comes down to studying a kind of noneuclidean trigonometry in Minkowski spacetime, as suggested by the following table:
|Kleinian Geometry||Euclidean plane||Galilean plane||Minkowski plane|
|Quadratic form||positive definite||degenerate||non-degenerate but indefinite|
|type of isotropy||rotations||shears||boosts|
|Algebra over R||complex numbers||dual numbers||split-complex numbers|
|Spacetime interpretation||none||Newtonian spacetime||Minkowski spacetime|
|slope||tan ? = m||tanp ? = u||tanh ? = v|
|"cosine"||cos ? = (1+m2)-1/2||cosp ? = 1||cosh ? = (1-v2)-1/2|
|"sine"||sin ? = m (1+m2)-1/2||sinp ? = u||sinh ? = v (1-v2)-1/2|
|"secant"||sec ? = (1+m2)1/2||secp ? = 1||sech ? = (1-v2)1/2|
|"cosecant"||csc ? = m-1 (1+m2)1/2||cscp ? = u-1||csch ? = v-1 (1-v2)1/2| | <urn:uuid:269a35bf-6c36-4f75-9a69-d7417ce3fffb> | 3.9375 | 3,530 | Knowledge Article | Science & Tech. | 37.617146 | 95,533,935 |
Measuring Reactions at the Single Molecule Level
Credit: Arizona State University
DNA, the stuff of life, may very well also pack quite the jolt for engineers trying to advance the development of tiny, low-cost electronic devices.
Much like flipping your light switch at home---only on a scale 1,000 times smaller than a human hair---an ASU-led team has now developed the first controllable DNA switch to regulate the flow of electricity within a single, atomic-sized molecule. The new study, led by ASU Biodesign Institute researcher Nongjian Tao, was published in the advanced online journal Nature Communications ( DOI: 10.1038/ncomms14471).
“It has been established that charge transport is possible in DNA, but for a useful device, one wants to be able to turn the charge transport on and off. We achieved this goal by chemically modifying DNA,” said Tao, who directs the Biodesign Center for Bioelectronics and Biosensors and is a professor in the Fulton Schools of Engineering. “Not only that, but we can also adapt the modified DNA as a probe to measure reactions at the single-molecule level. This provides a unique way for studying important reactions implicated in disease, or photosynthesis reactions for novel renewable energy applications.”
Engineers often think of electricity like water, and the research team’s new DNA switch acts to control the flow of electrons on and off, just like water coming out of a faucet.
Previously, Tao’s research group had made several discoveries to understand and manipulate DNA to more finely tune the flow of electricity through it. They found they could make DNA behave in different ways — and could cajole electrons to flow like waves according to quantum mechanics, or “hop” like rabbits in the way electricity in a copper wire works —creating an exciting new avenue for DNA-based, nano-electronic applications.
Tao assembled a multidisciplinary team for the project, including ASU postdoctoral student Limin Xiang and Li Yueqi performing bench experiments, Julio Palma working on the theoretical framework, with further help and oversight from collaborators Vladimiro Mujica (ASU) and Mark Ratner (Northwestern University).
To accomplish their engineering feat, Tao’s group, modified just one of DNA’s iconic double helix chemical letters, abbreviated as A, C, T or G, with another chemical group, called anthraquinone (Aq). Anthraquinone is a three-ringed carbon structure that can be inserted in between DNA base pairs but contains what chemists call a redox group (short for reduction, or gaining electrons or oxidation, losing electrons).
These chemical groups are also the foundation for how our bodies’ convert chemical energy through switches that send all of the electrical pulses in our brains, our hearts and communicate signals within every cell that may be implicated in the most prevalent diseases.
The modified Aq-DNA helix could now help it perform the switch, slipping comfortably in between the rungs that make up the ladder of the DNA helix, and bestowing it with a new found ability to reversibly gain or lose electrons.
Through their studies, when they sandwiched the DNA between a pair of electrodes, they careful controlled their electrical field and measured the ability of the modified DNA to conduct electricity. This was performed using a staple of nano-electronics, a scanning tunneling microscope, which acts like the tip of an electrode to complete a connection, being repeatedly pulled in and out of contact with the DNA molecules in the solution like a finger touching a water droplet.
“We found the electron transport mechanism in the present anthraquinone-DNA system favors electron “hopping” via anthraquinone and stacked DNA bases,” said Tao. In addition, they found they could reversibly control the conductance states to make the DNA switch on (high-conductance) or switch-off (low conductance). When anthraquinone has gained the most electrons (its most-reduced state), it is far more conductive, and the team finely mapped out a 3-D picture to account for how anthraquinone controlled the electrical state of the DNA.
For their next project, they hope to extend their studies to get one step closer toward making DNA nano-devices a reality.
“We are particularly excited that the engineered DNA provides a nice tool to examine redox reaction kinetics, and thermodynamics the single molecule level,” said Tao.
This article has been republished from materials provided by Arizona State University. Note: material may have been edited for length and content. For further information, please contact the cited source.
Xiang, L., Palma, J. L., Li, Y., Mujica, V., Ratner, M. A., & Tao, N. (2017). Gate-controlled conductance switching in DNA. Nature Communications, 8, 14471. doi:10.1038/ncomms14471
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Plants are stakeholders in a subtle and complex chemical warfare to secure optimal growth conditions. Although it has been known for decades that plants produce and release chemical substances to fight their neighbors, it has remained unclear how exactly these compounds act on other plants. A team of German and French scientists has been able to show that one particular class of plant toxins slows down the development of competing plants by specifically acting on the structure of their genome.
Plants are in a constant competition with their neighbors for limited resources such as light, nutrients and water. Only the fittest survive and reproduce. To defend their territory against invading competitors, plants employ so-called allelochemicals, toxic compounds that can inhibit growth and development of other plants. The existence of this chemical warfare, referred to as ‘allelopathy’, is widespread among many plant species, and has been known for a long time to scientists and agriculturists.
To have an advantage over their neighbors, some plant species release chemicals from their roots (e.g. DIBOA). These compounds can get degraded in the soil and turn into toxic substances.
Claude Becker, Sebastián Petersen (Max Planck Institute for Developmental Biology) and Markus Burkard (University Hospital Tübingen)
Plants are able to release chemical compounds from their roots into the soil, where the substances decay or are modified by microbes. Some of these products are toxic when the roots of neighboring plants take them up. Work by Sascha Venturelli and colleagues now sheds light on the inner workings of this plant chemical warfare (The Plant Cell).
Claude Becker, one of the leaders of the study, explains the importance of the findings: “The phenomenon has been known for years, and many classes of allelochemicals have been identified over the last decades, but for first time we now understand the molecular mechanism of such a ‘territorial behaviour’ of plants”.
The scientists investigated the role a specific class of plant secondary metabolites, the cyclic hydroxamic acids DIBOA and DIMBOA. These are released by several grass species, and their degradation products are well known for their phytotoxicity.
Through structural and biochemical analyses, followed by physiological experiments, Venturelli and colleagues could show that these compounds inhibit the activity of so-called histone deacetylases. These enzymes bind to histones, a group of proteins that together with DNA form the genetic material, also known as chromatin. Histone deacetylases remove acetyl side chains from these histones, causing compaction of the DNA and leading to a reduction in gene expression.
In the model plant Arabidopsis thaliana, the scientists found that inhibition of histone deacetylases by the plant toxins lead to more histone acetylation and an increase in gene expression, ultimately causing plant growth to slow down. The study thus not only presents the first molecular mechanism for allelopathy, but also illustrates how environmental toxins can alter chromatin structure and gene expression.
Allelochemicals are important regulators in natural and agricultural plant communities, and have repeatedly been associated with the success of invasive species in their new habitats. But there is more: “Herbal natural products in general hold great potential for the therapy of human diseases”, says Sascha Venturelli from the University Clinics Tübingen, medical scientist and first author of the study, and continues: “We have found that these particular compounds efficiently inhibit the growth of human cancer cells, too.”
Indeed some inhibitors of histone deacetylases have already been approved as anti-cancer drugs. Michael Bitzer and Ulrich Lauer, initiators and co-advisors of the study explain on-going efforts: “Clinical trials at the University Clinics Tübingen currently assess the efficacy of these plant toxins in cancer patients”. Understanding the mode of action of plant toxins could therefore also be of wider significance for medical research.
Contributing authors and institutes:
Sascha Venturelli, Alexander Berger, Kyra von Horn, Ulrich M. Lauer and Michael Bitzer from the Department of Internal Medicine I, Medical University Clinic, University of Tübingen, Germany;
Regina G. Belz from the Institute of Plant Production and Agroecology in the Tropics and Subtropics, University of Hohenheim, Stuttgart, Germany;
Andreas Kämper, André Wegner and Oliver Kohlbacher from the Applied Bioinformatics Group, University of Tübingen, Tübingen, Germany;
Alexander Böcker from the Evotec AG, Hamburg, Germany;
Gérald Zabulon and Fredy Barneche from the Institut de Biologie de l’Ecole Normale Supérieure (IBENS), CNRS, Paris, France;
Tobias Langenecker, Detlef Weigel and Claude Becker from the Department of Molecular Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
Venturelli et al.
Plants release precursors of histone deacetylase inhibitor to suppress growth of competitors
Advance Publication, The Plant Cell, November 2015 tpc.15.00585
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A Grinnellian niche is determined by the habitat in which a species lives and its accompanying behavioral adaptations. An Eltonian niche emphasizes that a species not only grows in and responds to an environment, it may also change the environment and its behavior as it grows. The Hutchinsonian niche uses mathematics and statistics to try to explain how species coexist within a given community.
The notion of ecological niche is central to ecological biogeography, which focuses on spatial patterns of ecological communities. "Species distributions and their dynamics over time result from properties of the species, environmental variation..., and interactions between the two—in particular the abilities of some species, especially our own, to modify their environments and alter the range dynamics of many other species." Alteration of an ecological niche by its inhabitants is the topic of niche construction.
The majority of species exist in a standard ecological niche, sharing behaviors, adaptations, and functional traits similar to the other closely related species within the same broad taxonomic class, but there are exceptions. A premier example of a non-standard niche filling species is the flightless, ground-dwelling kiwi bird of New Zealand, which feeds on worms and other ground creatures, and lives its life in a mammal-like niche. Island biogeography can help explain island species and associated unfilled niches.
The ecological meaning of niche comes from the meaning of niche as a recess in a wall for a statue, which itself is probably derived from the Middle French word nicher, meaning to nest. The term was coined by the naturalist Roswell Hill Johnson but Joseph Grinnell was probably the first to use it in a research program in 1917, in his paper "The niche relationships of the California Thrasher".
The Grinnellian niche concept embodies the idea that the niche of a species is determined by the habitat in which it lives and its accompanying behavioral adaptations. In other words, the niche is the sum of the habitat requirements and behaviors that allow a species to persist and produce offspring. For example, the behavior of the California thrasher is consistent with the chaparral habitat it lives in—it breeds and feeds in the underbrush and escapes from its predators by shuffling from underbrush to underbrush. Its 'niche' is defined by the felicitous complementing of the thrasher's behavior and physical traits (camouflaging color, short wings, strong legs) with this habitat.
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Nuclear Magnetic Resonance
The behavior of compass needles in the Earth’s magnetic field was introduced in Chapter 1 to present the concept of magnetic resonance. A compass needle is actually a small bar magnet which oscillates at a particular frequency when driven from its resting state. The frequency of its oscillation is proportional to the field strength in which it finds itself. While the simplest means of stimulating a compass needle is by a simple tap of the finger, it can also be driven from its resting state by subjecting it to an alternating external magnetic field. When the alternation occurs at the needle’s natural or resonant frequency, the compass needle absorbs energy.
KeywordsMagnetic Field Nuclear Magnetic Resonance Resonant Frequency Gradient Magnetic Field Hydrogen Nucleus
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The aftershock sequence of the magnitude 7 earthquake that struck Haiti on Jan. 12, 2010, will continue for months, if not years. The frequency of events will diminish with time, but damaging earthquakes will remain a threat.
Michael Blanpied, USGS Associate Earthquakes Hazards Program coordinator, discusses concerns and precautions for the future in Haiti and the...
As Haiti copes with the aftermath of the magnitude 7 earthquake, which struck on Tuesday, January 12, 2010, the U.S. Geological Survey is working to gather information that can aid response efforts. Michael Blanpied, USGS Earthquakes Hazards Program coordinator, gives an update on the current situation in Haiti and answers questions about the global picture.
On January 12, 2010, Haiti was struck by the most violent earthquake in a century. Michael Blanpied, associate coordinator for the USGS Earthquake Hazards Program, answers questions about the earthquake, its severe shaking, and the possibility of additional hazards, such as landslides and a tsunami.
Carcinogenic compounds in a popular pavement sealer are tracked indoors, where they show up in high concentrations in house dust.
Listen as USGS hydrologist Barbara Mahler explains how she and her team identified the link between polycyclic aromatic hydrocarbons in coal-tar-based pavement sealcoat and house dust.
Scientists have reconstructed what the climate conditions were 3 million years ago, and are using these data as one of the closest analogs to estimate future climate conditions.
USGS scientists Harry Dowsett and Marci Robinson discuss some of their findings regarding carbon dioxide’s impact, Arctic conditions, and the deep ocean’s system.
- Scientists and volunteers are working to restore the Eastern population of the federally listed whooping crane
- The life history and migration of whooping cranes
A magnitude 5.8 earthquake occurred just south of the California-Mexico border shortly before 11 a.m. on Wednesday, December 30, and shaking from this earthquake was widely felt.
Ken Hudnut, Southern California Regional Coordinator for the USGS Earthquake Program, spends a few minutes filling in some details about this event.
The USGS is investigating the use of Twitter, a popular micro-blogging tool, to collect and analyze citizen accounts of earthquakes around the world. USGS scientists Paul Earle and Michelle Guy discuss this Twitter Earthquake Detection (TED) project.
On Thursday December 3, 2009, the USGS celebrated the 125th anniversary of topographic mapping at the USGS National Center in Reston, VA.
Hear clips of the celebration in this episode of CoreCast, including the history of USGS mapping, given by Mark DeMulder, director of the National Geospacial Program. Also, Kari Craun, director of the National...
The Johnson Creek watershed is an important resource in Portland, Oregon. It forms a wildlife and recreational corridor through densely populated areas of the Portland metropolitan area, as well as rural and agricultural land in Multnomah and Clackamas Counties. However, because of its location within an urban environment, there are often concerns, including worries about...
Thanks to a satellite collar, two innovative scientists, and a blog, people can follow the travels of Brutus, the ‘North Pole wolf’ as he leads his pack through the long arctic winter.
Listen as wolf researcher David Mech talks about why he and his team put this satellite collar on Brutus and what they hope to learn about these arctic wolves.
When a 40-foot tsunami wave hit the shores of American Samoa on Sept. 29, 2009, thousands of locals made it safely to higher ground, thanks to education efforts and research.
Listen to an interview with USGS oceanographer and tsunami researcher Bruce Jaffe as he explains why this post-tsunami research is essential for keeping people safe in future tsunamis....
Public Lecture Sneak Peek: Geohazards of the Aleutian Islands -- Great Earthquakes, Great Waves, and Great Volcanic Explosions!
To increase to increase public awareness during Native American Indian National Heritage Month, we will be discussing the anthropology of indigenous peoples in the Aleutian Islands and how continued scientific research can help future forecasting of mega-earthquake and transoceanic tsunami probabilities.
Right now in Florida, non-native, giant constrictor snakes—pythons, anacondas, and the boa constrictor—are being found in the wild, and two species have established several breeding populations. The snakes pose a considerable resource management challenge for agencies charged with preserving native ecosystems and species. USGS research wildlife biologist Bob Reed discusses...
Increasing nitrogen emissions from motor vehicles, energy production, and agriculture are being deposited in lakes throughout the world, directly affecting lake biology and associated food webs. Alpine lake ecosystems are especially vulnerable to this deposition. USGS scientist Jill Baron, co-author of two new studies on how increased nitrogen pollution can affect lake...
The United States is using less water than during the peak years of 1975 and 1980, according to USGS water use estimates for 2005. Despite a 30 percent population increase during the past 25 years, overall water use has remained fairly stable.
So what else do we know--and not know--about water use in the U.S.? Learn from a USGS scientist and partners, and hear what...
Tsunamis are devastating. Usually associated with earthquakes in the Pacific, these giant surges of oceanic water can kill thousands and do billions of dollars of damage in minutes. Surprisingly, most people in Oregon are not aware of the tsunami history and hazard along our very own coast. Listen in as we examine the science of tsunamis and sit down for a special...
Public Lecture Sneak Peek: Paddling for a Purpose in a Troubled Sea--Sampling the Salish Sea During Tribal Canoe Journeys
USGS Menlo Park Science Center, Bldg. 3, Conference Room A, 7:00PM
Several USGS scientists are investigating the problem of fatal bat and bird collisions with wind turbines. USGS scientist and bat specialist Dr. Paul Cryan at the Fort Collins Science Center chats with Juliette Wilson about whether we can have our wind turbines and healthy populations of bats and birds too. | <urn:uuid:4932ae47-f5a2-4ce0-a12d-73ab010fae20> | 3.015625 | 1,603 | Content Listing | Science & Tech. | 40.112444 | 95,534,039 |
I often hear people, the popular press, and even "scientists" say things like "DNA contains all the information necessary to create life." Seems to me pretty clear that the claim isn't true, for one simple reason: In order to function, DNA must be in a cell which already has all the structures in place to keep the cell alive, as well as to use the DNA to code proteins.
Seems analogous to a computer: DNA is comparable to the software, and the cell is comparable to the hardware. But in a computer, both the software AND the hardware contain information necessary to the function of the computer.
Same with a cell: DNA by itself doesn't contain all the information necessary for life. The rest of the cell probably contains just as much information (if not more) in the configuration and function of all its organelles.
How much of the total information necessary for life is in the DNA? And how did the rest of the information come to be encoded in the cell? Someday maybe we'll know.
WJM Throws Down the Gauntlet
3 hours ago | <urn:uuid:d0eea012-379d-4543-958e-725b75dbaa6f> | 2.734375 | 224 | Comment Section | Science & Tech. | 55.132778 | 95,534,057 |
Seahorse genetic secrets unveiled
Scientists say they sequenced the genome of a seahorse species for the first time and identified the genetic underpinning for certain peculiarities like male pregnancy
Washington: Scientists have unlocked some of the genetic secrets of the weird and wondrous seahorse including its exotic eccentricity of male pregnancy.
Researchers said they sequenced the genome of a seahorse species for the first time and identified the genetic underpinning for certain peculiarities in this equine-looking fish group that inhabits coastal waters around the world.
Seahorses boast a host of oddities. Males, not females, carry and give birth to babies. They swim upright, not horizontally. They have horse-like heads, tube-like snouts and no teeth. They have grasping tails to grip seagrasses and corals to avoid being swept away by currents.
Their bodies are covered in bony plates. Unlike most fish, they lack tail and pelvic fins. Their eyes work independently, letting them look forward and backward simultaneously. And they can change colours to camouflage themselves.
“They are such iconic animals, one of the examples of the exuberance of evolution,” said evolutionary biologist and genome researcher Axel Meyer of Germany’s University of Konstanz, one of the researchers in the study published in the journal Nature.
“Their numbers are declining due to habitat destruction and harvest by humans,” added molecular biologist Byrappa Venkatesh of Singapore’s Agency for Science, Technology and Research (A*STAR).
The researchers analysed the genome of the Southeast Asian tiger tail seahorse, which reaches 4 inches (10 cm) long and boasts a yellow-and-black banded tail. It had the fastest rate of molecular evolution among any fish whose genome has been studied.
Male seahorses possess a brood pouch. During mating, a female deposits eggs into the male’s pouch. The male fertilizes the eggs internally and carries them in the pouch until they hatch, releasing the fully formed offspring into the sea.
A gene present in other fish that plays a role in egg hatching underwent duplication in the seahorse and assumed a new role, helping the advent of the male pouch.
Genes that in people and other animals play a role in tooth production were mutated in seahorses and lost functionality. Lacking teeth, seahorses use their snout to suck in plankton and other tiny prey.
A gene involved in development of pelvic fins in other fish and legs in humans was absent in seahorses, and they lack these fins. Instead, seahorses swim by using a small fin on their back that beats rapidly, with tiny pectoral fins placed near the back of the head used for steering. Reuters
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Roskosmos specialists started developing a medium-class reusable rocket in response to Falcon 9 carrier created by Elon Musk.
According to the project, the unification with the Soyuz-5 spaceship will make it possible to launch the future domestic rocket from Baikonur, Vostochny cosmodromes, as well as from a floating cosmodrome in the Pacific Ocean.
The project, which is the development of engineers of Energia Space Corporation and Progress Space Center, is to be completed in late November. The new rocket will be very important for Russia to keep its position on the market of space services.
The new rocket, experts say, will be able to land independently, similarly to the Falcon 9 of SpaceX. In the USA, two private companies have already developed rockets, the first stages of which land after takeoff. Two years ago, Blue Origin tested a single-stage light-weight carrier rocket.
In 2017, SpaceX held 16 launches of Falcon 9 rocket, and three of them were conducted with the repeated use of previously launched stages. At the same time, well-known entrepreneur Elon Musk has built his multibillion-dollar empire with the help of billions of state subsidies.
Musk's Tesla Motors Inc., SolarCity Corp. and Space Exploration Technologies Corp., known as SpaceX, have jointly benefited from 4.9 billion dollars of government support.
Not that long ago, the SpaceX administration said that the earlier announced benefit of the reusable Falcon-9 rocket was overestimated. The rocket, as it turns out, can only save up to ten percent of all costs.
Experts believe that the Falcon rocket is a look back to the 1960s, because the US rocket is comparable to the Soviet Proton M rocket, which the USSR developed in 1965. In addition, the USSR started developing reusable space engines in 1976 and finished the work in 1980.
In fact, Elon Musk sells "well-forgotten" old ideas to NASA under the guise of unprecedented innovations, fools the US government for a few billions of dollars, and now he plays the game of spaceships that fall and explode every other time and do not bring any economic benefit. Yet, the whole project looks innovative, expensive and great.
"Musk promotes his superprojects and innovations which he implements at the expense of the state budget against the background of massive PR campaigns. He brushes aside some of his projects and comes up with new ones immediately, like the colonisation of Mars. As long as the government sponsors his ideas, the show will go on," bloggers wrote.
The US Dream Chaser shuttle has recently conducted its first successful landing. According to NASA website, the compact shuttle was designed on the basis of the US orbital plane HL-20, which, in turn, was based on the model of the Soviet unmanned BOR-4 missile.
According to developers, the Dream Chaser will be used to deliver cargo and crews of up to seven people to near-Earth orbit. The first flight to the ISS is scheduled for 2020.
Soviet BOR spacecraft were known as "unmanned orbital rocket-propulsion vehicles," one of which (MiG-105) was tested at an altitude of 100 kilometres in 1969.
Read article on the Russian version of Pravda.Ru
The choice of the city of Helsinki is not incidental as the capital of Finland had hosted US-Soviet negotiations on the limitation of nuclear stockpiles in 1969 | <urn:uuid:c46e1065-ba6f-4a3d-981b-536b710d4022> | 2.734375 | 697 | News Article | Science & Tech. | 46.501604 | 95,534,086 |
A Moon-Based Telescope
Using lunar dust, NASA scientists could build a large, inexpensive telescope on the moon.
NASA scientists have developed a simple and inexpensive method for turning lunar dust into a concrete-like material that can be used instead of glass to build large telescope mirrors on the moon. The scientists made the material by mixing carbon nanotubes and epoxies–glue-like materials–with a crushed rock compound that has the same composition as lunar dust. Then they spun the material on a pottery wheel to create a mirror blank with the parabolic shape of a telescope mirror.
Building a telescope mirror in which 90 percent of it is made from moon dust means that the few remaining parts can be carried to the moon, and scientists are no longer limited with regard to the size of the telescope they can make, says Peter Chen, a scientist at Goddard Space Flight Center who’s working on the new method.
The power of a telescope is proportional to the size of its mirror. The James Webb Space Telescope, which is scheduled to succeed the Hubble telescope in 2013, will be the largest to fly to space with a mirror that is six meters in diameter. Chen says that, using the new method, scientists could build mirrors on the moon that are 50 meters in diameter–the ideal size to peer deep into the universe, find Earth-like planets in our solar system, and search for the presence of life.
Indeed, say experts, the moon is an ideal spot for astronomy. “The moon has no atmosphere, which means no blurring or absorption of starlight, and it provides a large, stable platform,” says Chen.
Chen’s group is not the only one working on an approach to build giant, powerful mirrors on the moon. Scientists Robert Angel, at the University of Arizona, and Ermanno F. Borra, at the Université Laval, in Quebec, are working on a spinning liquid-mirror telescope. While both methods have similar goals, they have different technical challenges, says Angel. The liquid-mirror telescope has to be spun at an accurate rate throughout its lifetime, and thus can only point in one direction. “If the NASA scientists can freeze their liquid surface into something accurate–epoxy mirrors change shape when they set–they can make a more versatile telescope than ours,” says Angel.
Most telescope mirrors are made of highly specialized materials, like beryllium or silicon graphite, that are rare and expensive. Using these to make large, perfectly smooth optical surfaces is also an involved process. Very tiny flaws in the materials can make a mirror unusable.
In contrast, NASA scientists used a combination of readily accessible materials: carbon nanotubes, epoxies, and a crushed rock that has the same composition and grain size as lunar dust. The mixture created a very strong material with the consistency of concrete. The scientists then added another layer of epoxy and spun the material to generate a 12-inch-wide mirror with the parabolic shape of a telescope mirror. Although spinning epoxy is unlikely to freeze the mirror into a perfect optical surface, it is easy to adapt standard industrial processes to make telescope mirrors of high quality and smoothness, says Chen. He and his group have also developed a noncontact method called reactive ion etching, which they have shown can modify the epoxy surface at will, remotely.
“Demonstrating this [method] on a 12-inch mirror is just a first small step towards what it would take to build a production facility capable of making a 50-meter telescope,” says Lee Feinberg, a NASA scientist who manages the James Webb telescope.
A major concern regarding equipment constructed on the moon would be keeping high-precision mechanical surfaces (joints, bearings, and so on) from being clogged by dust. There are also large temperature swings between daytime and nighttime that would place high demands on the integrity of the moving mechanical parts.
But first, NASA has to get to the moon, a feat that it hopes to accomplish by 2020.
Couldn't make it to EmTech Next to meet experts in AI, Robotics and the Economy?Go behind the scenes and check out our video | <urn:uuid:3fedb363-7833-4cc4-a65a-3bbad73199ab> | 3.984375 | 866 | News Article | Science & Tech. | 38.443795 | 95,534,091 |
Stop Shark Attacks With Vomit!
The hagfish has developed a slimy substance that it uses to defend itself against sharks and other predators. The slime blocks the gills, making sharks cough and struggle to breathe.
The hagfish belongs to a group of animals that biologists consider the most primitive among vertebrates. But when they must protect themselves against enemies, they turn out to be rather sophisticated.
The hagfish releases a slimy substance that makes larger predatory fish gasp for breath. The slime swiftly blocks the predatory fish’s gills, so it cannot absorb oxygen. When a hungry shark dares to enter its teeth into a hagfish, it will hence very quickly let go of its prey again, allowing the hagfish to escape unharmed.
Biologists from three US universities have studied the scenario via several video recordings and were inspired to take a closer look at the skin of the hagfish to find out how it can escape the attacks so easily. The scientists assumed that the skin was very sturdy and hence difficult to penetrate for the teeth of the predatory fish. So, they tested the breaking strength of hagfish skin, comparing it to the skin of 21 other fish species. However, the study showed that hagfish skin is not any sturdier than that of other species. When the hagfish escapes predator fish teeth almost unharmed, it is instead due to the fact that the skin is very loose.
Not only the scientists’ video recordings, but also other observations demonstrate the efficiency of hagfish defence mechanisms. When biologists study the stomach contents of other large predatory fish, they very rarely come across hagfish remains. | <urn:uuid:06e93801-5c6c-4769-b55b-0a9e035ccca6> | 3.296875 | 346 | News Article | Science & Tech. | 46.573895 | 95,534,094 |
How would you describe the saturated zone?
Why is it about the subsurface that can influence the transport of a contaminant and give three examples.© BrainMass Inc. brainmass.com July 21, 2018, 9:15 pm ad1c9bdddf
The Saturated Zone is defined as follows:
"The zone in which all the voids in the rock or soil are filled with water at greater than atmospheric pressure. The water table is the top of the saturated zone in an unconfined ...
The solution describes the saturated zone as well factors that influence the transport of a contaminant. | <urn:uuid:196bc172-5e72-4205-8f59-f0245b5e6064> | 3.75 | 126 | Q&A Forum | Science & Tech. | 58.985376 | 95,534,118 |
Publishing Note: Due to Bob Nichol's other commitments the city-specific radiation reporting will now be published every 2 weeks until further notice. The next such report will be on April 22, 2017. I will update the weekly Hiroshima bomb equivalents information. This is to keep you as aware and informed as possible, not alarm you, though you should be alarmed, and is scientific FACT, not sensationalistic nonsense. Everything here is active-linked for your own verification, or not; I encourage you to do so. The radiation's not going anywhere, folks, but we are... - CP
"Now I am become Death, the destroyer of worlds.”
Updated by CP April 15, 2017: Fukushima Equals 14,325.45 Hiroshima Bombs Today, More Tomorrow; There is No Place On Earth to Escape the Rad: The 3 melted-through cores of the destroyed reactors, totaling over 600 tons, at Fukushima daily release the radioactive equivalent of 6.45 Hiroshima bombs directly into the atmosphere and the Pacific Ocean. As of April 15, 2017, 2,221 days since the disaster began, this equals the detonation of 14,325.45.3 Hiroshima atomic bombs and it is still going strong, with no end in sight, considering that the half-life of uranium-238 is about 4.47 billion years and that of uranium-235 is 704 million years. There is no technology on this planet to deal with this situation. There are only 336 cities on Earth with more than one million people. That is the equivalent of 42.63 Hiroshima atomic bombs apiece. First thing, grasp the difficult concept that this is an ELE or Extinction Level Event. The deadly meltdown and dispersion of radioactive fuel throughout the world is on-going to this day. There is no escaping our fate, there are no solutions. No one is exempt. The radioactive particles are all over the world now.
For last week's city-specific radiation levels please go here: | <urn:uuid:d6a437cf-cc8d-452f-bf72-302a328ff070> | 2.78125 | 401 | Personal Blog | Science & Tech. | 61.143385 | 95,534,136 |
Since its inception a decade ago, sol gel encapsulation has opened up an intriguing new way to immobilize biological materials. An array of substances, including catalytic antibodies, DNA, RNA, antigens, live bacterial, fungal, plant and animal cells, and whole protozoa, have been encapsulated in silica, metal-oxide, organosiloxane and hybrid sol gel polymers. The advantages of these living ceramics might give them applications as optical and electrochemical sensors, diagnostic devices, catalysts, and even bioartificial organs. With rapid advances in sol gel precursors, nanoengineered polymers, encapsulation protocols and fabrication methods, this technology promises to revolutionize bioimmobilization.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:28a97083-792c-466d-876e-369b42a42eb0> | 2.8125 | 169 | Academic Writing | Science & Tech. | -15.682601 | 95,534,144 |
Compare and contrast relative age dating with radiometric age dating. Discuss the limitation of each?© BrainMass Inc. brainmass.com July 19, 2018, 12:18 am ad1c9bdddf
Please see response attached (see Posting 107553.doc) (also below), including one supporting article. I hope this helps and take care.
I am wondering how well you understand these concepts, as it is very important to understand how relative age dating and radiometric age dating work, before you can compare and contrast the two types of dating. Let's take a closer look, which you then draw on for your final compare and contrast discussion. I perhaps wrote more than you need, so please keep what fits.
1. Compare and contrast relative age dating with radiometric age dating. Discuss the limitation of each?
Relative age dating...
First, relative dating methods involve placing geological events in a sequential order as determined from their position in the rock record. Relative dating will not tell us how long ago a particular event occurred; only that one event preceded the other (disadvantage). Four principles of relative dating are of importance for this question:
1. Principle of superposition: Nicolas Steno realized that correct relative ages of horizontal (undeformed) strata could be determined by their position in a sequence of rock.
2. Principle of cross-cutting Relationship: holds that an igneous intrusion or a fault must be younger than the rocks it intrudes or displaces. This principle is very important in relative dating of geologic events and interpreting Earth history.
3. Principle of lateral continuity: states that sediment extends laterally in all directions until it thins and pinches out or terminates against the edge of the depositional basin.
4. Principal of original horizontality: Steno reasoned that sediment is deposited in essentially horizontal layers (Wicander & Monroe, 1995).
Hypothetical Example: Using relative dating methods
Field setting of the ...
This solution compares and contrasts relative age dating with radiometric age dating, and points out potential limitations of each. Supplemented with one supporting article. | <urn:uuid:697b9c42-5ae3-430a-b874-ef9c634ace17> | 3.296875 | 437 | Q&A Forum | Science & Tech. | 35.371449 | 95,534,195 |
Sendes vanligvis innen 7-15 dager
Modern physics rests on two fundamental building blocks: general relativity and quantum theory. General relativity is a geometric interpretation of gravity while quantum theory governs the microscopic behaviour of matter. Since matter is described by quantum theory which in turn couples to geometry, we need a quantum theory of gravity. In order to construct quantum gravity one must reformulate quantum theory on a background independent way. Modern Canonical Quantum General Relativity provides a complete treatise of the canonical quantisation of general relativity. The focus is on detailing the conceptual and mathematical framework, on describing physical applications and on summarising the status of this programme in its most popular incarnation, called loop quantum gravity. Mathematical concepts and their relevance to physics are provided within this book, which therefore can be read by graduate students with basic knowledge of quantum field theory or general relativity. | <urn:uuid:8d602868-5111-4209-a76d-a729957bdf95> | 3.453125 | 175 | Product Page | Science & Tech. | 8.648792 | 95,534,209 |
The ozone layer is thinning and we do not yet know to what extent future ozone losses will be affected by climate change, or what impact this will have on human health.
For this reason, the European Research Commissioner Philippe Busquin today welcomed the start of the first phase of the VINTERSOL (Validation of International Satellites and Study of Ozone Loss) campaign, composed of national and EU projects. VINTERSOL will be closely co-ordinated with the SAGE III Ozone Loss and Validation Experiment (SOLVE II), a US NASA (National Aeronautics and Space Administration) sponsored campaign. The kick-off meeting takes place in Brussels today. The joint initiative will involve 350 scientists from the European Union, Canada, Iceland, Japan, Norway, Poland, Russia, Switzerland and the United States. Aircraft, large and small balloons, ground-based instruments and satellites will be used to measure ozone and other atmospheric gases and particles. The project aims to improve understanding of Arctic ozone depletion, and at upgrading satellite observation of the ozone layer.
"This joint project is in the spirit of the 1998 European Union-United States Science and Technology Co-operation Agreement, which fosters joint scientific endeavours," said Commissioner Philippe Busquin. "It brings together researchers from around the world and aids better understanding of what happens in the ozone layer over the Arctic region, and therefore addresses global climate change and the effects on human health of overexposure to sun radiation. It will help us to meet the requirements of the Montreal Protocol on ozone-depleting substances, fine-tune our policies with sound scientific evidence and upgrade Europes role in the international scientific arena. This is a concrete illustration of the EUs intention to build a European GMES capacity (Global Monitoring for the Environment and Security)."
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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19.07.2018 | Earth Sciences
19.07.2018 | Power and Electrical Engineering
19.07.2018 | Materials Sciences | <urn:uuid:59fa72ac-a3a9-465e-b423-dd435b92deea> | 3.140625 | 1,026 | Content Listing | Science & Tech. | 34.844013 | 95,534,220 |
This is the latest of several discoveries that are leading us towards a better understanding of one of the most complex processes in nature – the process of memory creation and consolidation in the human brain. This latest research was published recently in the prestigious journal Nature Neuroscience.
The human brain constantly receives sensory stimuli from the outside world: sounds, tastes, visuals, touch and smells. A very small fraction of these stimuli which are recorded in short term memory actually become part of our long term memory. Previous studies in the laboratory for "Molecular Mechanisms of Learning and Memory" at the University of Haifa identified a protein linked to the quality of long term memories. In the current study, the researchers were looking to understand how long term memories are stabilized.
The research team led by Prof. Kobi Rosenblum, Head of the Department of Neurobiology and Ethology at the University of Haifa, and PhD student Alina Elkobi together with Drs. Katya Belelovsky and Liza Barki and in cooperation with Dr. Ingrid Ehrlich from the Friedrich Miescher Institute at the University of Basel, Switzerland, searched for a protein which is present during the process of memory formation and is actually an essential factor in the process.
Using taste learning in mice, the researchers found learning-related induction of the protein PSD-95 in the brain cortex "taste center" during the process of memory creation. However, when the mice were exposed to known tastes, PSD-95 was not induced in this center of the brain cortex.
In order to prove that PSD-95 is essential for the process of memory creation, the researchers used two different groups of mice who had undergone the same tests for taste learning. Using genetic engineering, the researchers halted the process of PSD-95 production in the nerve cells of the "taste center" in the cortex. The group whose PSD-95 production was stopped had no memory of new tastes the day after being introduced to them while the other group remembered the tastes – demonstrating that a new memory was created when PSD-95 was induced and that the information disappeared from the brain when the protein was not induced.
The study further examined the effect of PSD-95 production on existing memories. Mice that had already been introduced to and remembered certain tastes were genetically engineered to stop producing the protein and they still remembered the tastes – demonstrating that while PSD-95 induction is essential for memory creation, its absence does not affect memory retention.
"The process of long term memory creation in the human brain is one of the incredible processes which is so clearly different than "artificial brains" like those in a computer. While an "artificial brain" absorbs information and immediately saves it in its memory, the human brain continues to process information long after it is received, and the quality of memories depends on how the information is processed. One of the first processes to be affected in neurodegenerative diseases like Alzheimer's and Parkinson's is that of memory acquisition and processing.
In this research we identified one specific protein, among the many proteins active in brain synapses, whose production is essential for the brain to process and remember information it receives. The more we understand about the processes and elements involved in this complicated process, the sooner we will be able to develop medications which will delay the progression of cognitive degenerative diseases and enable patients to continue normative functioning," explains Prof. Rosenblum.
Laurie Groner | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Earth Sciences
19.07.2018 | Power and Electrical Engineering
19.07.2018 | Materials Sciences | <urn:uuid:ec0459a9-0ffb-448d-819e-b488c16273f9> | 3.671875 | 1,353 | Content Listing | Science & Tech. | 37.113334 | 95,534,221 |
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This book offers a timely overview and synthesis of biogeographic patterns of plants and fungi and their mycorrhizal associations across geographic scales. Written by leading experts in the field, it provides an updated definition of mycorrhizal types and establishes the best practices of modern biogeographic analyses. Individual chapters address the basic processes and mechanisms driving community ecology, population biology and dispersal in mycorrhizal fungi, which differ greatly from these of prokaryotes, plants and animals. Other chapters review the state-of-the-art knowledge about the distribution, ecology and biogeography of all mycorrhizal types and the most important fungal groups involved in mycorrhizal symbiosis. The book argues that molecular methods have revolutionized our understanding of the ecology and biogeography of mycorrhizal symbiosis and that rapidly evolving high-throughput identification and genomics tools will provide unprecedented information about the structure and functioning of mycorrhizal symbiosis on a global scale. This volume appeals to scientists in the fields of plant and fungal ecology and biogeography. | <urn:uuid:68d5696d-365e-4076-8d4e-d7d0d261065d> | 3.09375 | 231 | Product Page | Science & Tech. | -0.532045 | 95,534,235 |
In a stable climate, the ratio of new record highs to new record lows is approximately even. However in our warming climate, record highs have begun to outpace record lows, with the imbalance growing for the past three decades. This trend is one of the clearest signals of climate change that we experience directly.
The intense cold hitting the United States during the first week of 2018 continued with a heavy snowstorm that inundated the Northeast seaboard beginning the night of January 3 through January 4. The combined impact of the arctic outbreak and the intensified nor’easter landed a double whammy in which new record low temperature records were set.
Science studies and models report that the outbreak of arctic air bringing freezing temperatures to the lower United States is consistent with the climate disruption expected on a warming planet where the Arctic heats up faster and cold air is displaced to the south.
Unusually warm offshore waters also amplified the temperature contrast between land and ocean surfaces. This temperature contrast is what generally fuels nor’easters. These conditions over the Atlantic are consistent with the long-term climate change trends that intensify nor’easters.
While climate change warms the planet as whole, it also disrupts regional weather patterns, sometimes displacing cold air to the south. The overall warming trend continues but cold conditions can move. The record setting heat events recently observed further north in parallel to cold conditions in the continental US are consistent with this pattern of disruption.
Higher temperatures, drier conditions, increased fuel availability, and growing warm seasons—all linked to climate change—are increasing wildfire risk in California.
In 2017, the combination of a wet winter followed by extreme heat and dry conditions has fueled record wildfires in many Western states.
In early December, a series of fires extended this trend when they erupted in the mountains north of Ventura and Los Angeles, California.
The Thomas Fire, which began on the evening of December 4, is the largest blaze and grew quickly to nearly 31,000 acres (50 square miles) in less than 12 hours. As of January 1, 2018, the Thomas Fire was 92 percent contained and had burned 281,893 acres establishing it as largest fire in California recorded history. A mixture of dry foliage, low humidity and high sustained winds of more than 30 miles per hour led to its explosive growth, according to Fire Sgt. Eric Buschow. Other major fires included the Creek and Rye events.
Research indicates a direct causal link between human-induced climate change and increased wildfire risk in California. Climate change has contributed to California's longer fire seasons, the growing number and destructiveness of fires and the increasing area of land consumed.
Trends in California driven by climate change—including higher temperatures and drier conditions—are elevating the risk of dangerous and destructive wildfires across California and the western United States.
On October 8, a group of fires exploded across a wide swath of Northern California. Taken as a group, the fires are among the worst on record in the state in terms of lives and property lost. After just one week, the fires have killed at least 41 people, burnt more than 200,000 acres, destroyed or damaged more than 5,500 homes, and displaced 100,000 people. Governor Jerry Brown declared a state of emergency in Butte, Lake, Mendocino, Napa, Nevada, Orange, Sonoma and Yuba counties.
By the end, the Wine Country fires killed 42 people, destroyed 8,700 homes and buildings, and burned 245,000 acres. The event was deadliest, most destructive, and one of the largest fires in California history.
The combination of a wet winter followed by extreme heat and dryness has fueled record wildfires in many Western states. Climate change compounds the risks of wildfires by extending the length of the fire season and adding to the intensity of droughts and heat waves. Park Williams, a climate and drought expert, noted, “... the combination of dry fuel, extreme heat and climate change is a recipe for what we are seeing."
The record-breaking rainfall and flooding driven by Hurricane Maria—as well as Hurricanes Harvey and Irma just weeks before—is consistent with the long-term trend driven by climate change.
Hurricane Maria made landfall in Dominica as a Category 5 hurricane on September 18, then hit southeast Puerto Rico on September 20 with 155 mph winds and a central pressure of 917 millibars. It was the third strongest storm to make landfall in the United States. "1,000-year" rains inundated much of eastern and northwestern Puerto Rico. The storm knocked out power to the entire island of Puerto Rico, home to 3.5 million people, leading to a prolonged humanitarian crisis.
Extreme rainfall is increasing worldwide due to climate change. In Puerto Rico, rain falling in very heavy events increased at least 33 percent from 1958-2012. Seas are now higher due to global warming, so storm surge drives much further inland. There has also been a global increase in the observed intensity of the strongest tropical cyclones, correlated with observed trends in sea surface temperatures in recent decades.
NFIP claims rise alongside upward trends in extreme storm frequency . . .
The increasing frequency of US National Flood Insurance Program (NFIP) claims parallels the increasing frequency of extreme rainfall and flooding in the United States.
Higher temperatures and drier conditions—both linked to climate change—are increasing wildfire risk in California.
The La Tuna Fire erupted north of downtown Los Angeles and, at more than 7,000 acres, the fire is the largest to burn within Los Angeles' city limits.
While small compared to the biggest fires in California's history, the La Tuna Fire is notable for its proximity to a major city and its rapid growth amid unseasonably warm temperatures. The fire also erupted at the edge of the Angeles National Forest, a region where bark beetle activity has increased in recent years of extreme heat and drought.
"The greatest statewide heat wave ever recorded in California" began in late August and lasted through early September, as a major high pressure system stalled over the western United States. Many locations broke daily, monthly, and all time temperature records. Most notably, San Francisco broke its all time heat record, reaching 106°F on September 1.
Record breaking heat waves are a classic signal of climate change. The trend in global warming has contributed to the severity and probability of 82 percent of record-hot days globally over the 1961-2010 period.
The heat wave bears several signatures of heat waves on a warming planet: record-breaking heat, hot nights, high humidity, long duration, and increasing frequency.
This heat wave comes on the heels of June’s heat wave, which also broke temperatures records across the state.
Climate change is amplifying the damage done by hurricanes, by elevating sea levels and thus extending the reach of storm surge, and by loading storms with additional rainfall and thereby increasing flood risk.
In addition there is significant evidence linking climate change to the observed shift in the track of hurricanes such as Irma toward the US coast.
Hurricane Irma maintained maximum wind speeds of at least 180 mph for 37 hours, longer than any storm on Earth on record, passing Super Typhoon Haiyan, the previous record holder (24 hours). Irma’s maximum accumulated energy over 24 hours was the highest for any Atlantic hurricane on record. The storm intensified into a Category 5 with 185 mph winds on September 5, making it the most powerful Atlantic hurricane ever recorded outside of the Caribbean and Gulf of Mexico where warmer waters make those areas more prone to stronger cyclones.
Hurricanes are fueled by available heat. As global warming heats sea surfaces, the energy available to power hurricanes increases, raising the limit for potential hurricane wind speed.
Irma intensified in the Atlantic from September 4 to 5 as it entered a region of sea surface temperatures ranging from 0.9°F to 2.25°F (0.5°C to 1.25°C) above average, relative to a 1961-1990 baseline.
Climate change raises or amplifies the three primary hazards associated with hurricanes: storm surge, rainfall, and the power ceiling, aka potential speed limit, for hurricane winds.
Hurricane Harvey set a new national tropical cyclone rainfall record of 60.58 inches near Nederland, Texas. A December 2017 study found that global warming made the precipitation seen over Houston and the surrounding area on August 26–28 about 15 percent (8 to 19 percent) more intense, or equivalently made such an event three (1.5–5) times more likely. Climate change has been found to have significantly increased the rainfall in hurricanes. A warmer atmosphere holds more water vapor, feeding more precipitation into all storms including hurricanes, significantly amplifying extreme rainfall and increasing the risk of flooding.
Sea level rise has elevated and dramatically extended the storm surge driven by hurricanes - the main driver of damage for coastal regions.
Hurricanes are fueled by ocean heat. As climate change warms sea surfaces, the heat available to power hurricanes has increased, raising the limit for potential hurricane wind speed and with that an exponential increase in potential wind damage. Harvey intensified rapidly amid sea surface temperatures in the Gulf of Mexico up to 2.7 - 7.2°F (1.5 - 4°C) above average, relative to a 1961-1990 baseline. | <urn:uuid:0ad9d4a3-8740-4b80-a48b-129e665717de> | 3.78125 | 1,903 | Knowledge Article | Science & Tech. | 40.500828 | 95,534,249 |
Python programming which is currently in trend in IT field is an interpreted high-level programming language which is created in the year 1991. Python’s flexibility and scalability with other technologies like web development, automation testing, Machine language, Artificial intelligence are have become most popular and also listed in Top Trending Software Technologies 2018.
In this post let’s discuss the Beautiful Benefits of Learning Python Programming.
What is Python?
Python is an Object-oriented, high level and multipurpose language. Python is very easy to learn and can be interpreted to more number of Operating Systems including Unix based systems. Python makes debugging easily because there are no compilation steps in Python development and edit-test-debug cycle is very fast.
Python for Beginners
The important benefit of Python programming is it is easy to learn even by beginners. Python doesn’t require any prerequisites since it is a scripting language you can start programming in a couple of days itself. Our Python training program starts from scratch which makes the subject easy to learn from scratch and includes all advanced topics.
Python with Other Technologies
The flexibility and scalability of Python programming make it the best choice for the latest technologies. Even the developers also like to use Python as their primary programming language comparing other languages. Especially Data Scientist also used to prefer Python over Java while dealing with the data.
Python with Data Science
Data Science is the hottest technology in the industry with more number of job opportunities. In our previous article, we have discussed Why Data Scientist prefer Python over Java?,
Python provides effective libraries for Data Science, from which you can make the data analysis easily,
Data Scientist recommends Python as the best choice for Data Analysis and retrieving the useful information from the given data.
Check here our Python with Data Science Course Content.
Python with Selenium
Python high level scripting language is very much user friendly which makes the automation looks easy. Software testers used to prefer Python programming because of the following reason,
- Python program runs faster when comparing to Java programs
- Python programs are dynamically typed while Java is statically typed and uses tradition braces to start and end the blocks
- Simple and easy to program even for beginners
Python with AWS
We all know that Amazon Web Services is the popular and the most used cloud service platform where it covers more than 75% of business in the cloud computing field. The latest report from AWS states that it has more than 95 services on their cloud platform.
Since most of the organizations are moving towards cloud service platform because of its easy accessibility, cost-effective the requirement of AWS developers also increases.
AWS developers prefer to use Python for cloud computing development. AWS.amazon.com provides AWS SDK for Python (Boto3). Boto3 is the software development kit which is provided by AWS for the development using Python.
- Easy to use
- Object-Oriented API
- Low-level direct service access
Check here our Python with AWS Course Content.
Python with Machine Learning – chatbot
Python programming is popular with Machine Learning, This powerful interpreted language acts best for Machine learning other than R. Python act as a complete programming language for research and development process in the Machine Learning production.
Machine Learning is the method of teaching the system to automatically learn from its experience by using statistical techniques without being programmed. This field of computer science was invented by Arthur Samuel who involved himself in learning about computational theory in artificial intelligence. The whole part of Machine Learning structure is separated into two categories such as Supervised Learning and Unsupervised Learning.
Job Opportunities for Python Developers
Python has now a day become the most beneficial language which is preferred by developers all over the world to include it in different technologies as mentioned earlier. Learning Python programming from the Best Python training institute in India will be the best choice to be a professional Python developer and get placed easily. | <urn:uuid:0a78791e-b0e1-4baf-a2d1-a0874c12daf7> | 2.6875 | 787 | Product Page | Software Dev. | 26.42931 | 95,534,255 |
Latest Earth Topic Highlights
22 November 2017
The International Charter Space and Major Disasters has received a distinguished award for providing free satellite imagery, data and information to the global community during times of crises.
03 November 2017
A new, long-term and global dataset of soil moisture measurements from space has been released to help us better understand the water cycle and climate, monitor agriculture and manage our water resources.
30 October 2017
It appears that something good can come from something bad. Although rising global temperatures are causing seasonal snow cover to melt earlier in the spring, this allows for the snow-free boreal forests to absorb more carbon dioxide from our atmosphere.
25 October 2017
This year's Atlantic hurricane season has been a harsh reminder of the grief and devastation brought by these vast storms. Imaging the top of hurricanes from space is nothing new, but the Sentinel-1 satellites can see right through these towering spinning weather systems, measuring the sea surface below to help predict the storm's path.
17 October 2017
The Copernicus Sentinel-3A satellite captured different views of Hurricane Ophelia in the past week on its path towards Europe.
16 October 2017
When disaster strikes, a group of international space agencies pools its resources and expertise to support relief efforts on the ground. For the next six months, ESA will be leading the International Charter Space and Major Disasters as it brings information from satellites to the aid of the vulnerable.
Showing 7 - 12 of 689 results. | <urn:uuid:6c779799-a791-48b7-89c5-b4017f35422c> | 3.1875 | 302 | Content Listing | Science & Tech. | 34.783813 | 95,534,278 |
Alpine goats appear to be shrinking in size as they react to changes in climate, according to new research from Durham University.
The researchers studied the impacts of changes in temperature on the body size of Alpine Chamois, a species of mountain goat, over the past 30 years.
To their surprise, they discovered that young Chamois now weigh about 25 per cent less than animals of the same age in the 1980s.
In recent years, decreases in body size have been identified in a variety of animal species, and have frequently been linked to the changing climate.
However, the researchers say the decline in size of Chamois observed in this study is striking in its speed and magnitude.
The research, funded by the Natural Environment Research Council is published in the journal Frontiers in Zoology.
Lead author Dr Tom Mason, in the School of Biological and Biomedical Sciences, at Durham University, said: "Body size declines attributed to climate change are widespread in the animal kingdom, with many fish, bird and mammal species getting smaller.
"However the decreases we observe here are astonishing. The impacts on Chamois weight could pose real problems for the survival of these populations."
The team delved into long-term records of Chamois body weights provided by hunters in the Italian Alps.
They discovered that the declines were strongly linked to the warming climate in the study region, which became 3-4oC warmer during the 30 years of the study.
To date, most studies have found that animals are getting smaller because the changing climate is reducing the availability or nutritional content of their food.
However, this study found no evidence that the productivity of Alpine meadows grazed by Chamois had been affected by the warming climate. Instead, the team believes that higher temperatures are affecting how chamois behave.
Co-author Dr Stephen Willis, in the School of Biological and Biomedical Sciences, at Durham University, said: "We know that Chamois cope with hot periods by resting more and spending less time searching for food, and this may be restricting their size more than the quality of the vegetation they eat.
"If climate change results in similar behavioural and body mass changes in domestic livestock, this could have impacts on agricultural productivity in coming decades."
According to the authors, the future plight of the Chamois remains unclear.
Dr Philip Stephens, another co-author on the study, in the School of Biological and Biomedical Sciences, at Durham University, said: "The body mass of juvenile animals is critical to their ability to survive harsh winters.
"However, whether that becomes a problem will depend on the balance of future climate change between the seasons."
The research suggests that declining body size is a result of changes in both climate and the density of animals.
To counter declining body size in future, the researchers say it might be necessary to maintain Chamois populations at lower densities than occur at present, perhaps through changes in hunting regulations.
Dr Mason added: "This study shows the striking, unforeseen impacts that climate change can have on animal populations.
"It is vital that we continue to study how climate change affects species such as Chamois. Changes in body size could act as early-warning systems for worse impacts to come, such as the collapses of populations."
Leighton Kitson | Eurek Alert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:4ad58396-53f4-4964-9afc-8a9ab37d7236> | 3.59375 | 1,335 | Content Listing | Science & Tech. | 39.618822 | 95,534,285 |
Moon could be wetter than thought, say scientists
The Moon, long thought to be a dry, inhospitable orb, hosts surprisingly large sub-surface water reserves, which one day may quench the thirst of lunar explorers from Earth, scientists said Monday.
“We found the signature of the lunar interior water globally using satellite data,” Shuai Li, co-author of a study by scientists at Brown University in the United States, told AFP.
“Such water can be used as in situ resources for future exploration,” said Li, a postdoctoral researcher at the University of Hawaii and Brown Ph.D graduate.
Li noted scientists had believed the Moon to be “bone dry” until about a decade ago, when scientists found evidence of water — an essential ingredient for life — in pebble-like beads brought back by Apollo missions.
The Brown findings show numerous volcanic deposits distributed across the surface of the Moon contain “unusually high amounts of trapped water” compared with surrounding terrain.
They say discovery of water in the ancient deposits, which are believed to consist of glass beads formed by the explosive eruption of magma from beneath the Moon’s surface, boosts the idea that the lunar mantle is surprisingly water-rich.
“The key question is whether those Apollo samples represent the bulk conditions of the lunar interior or instead represent unusual or perhaps anomalous water-rich regions within an otherwise ‘dry’ mantle,” said Ralph Milliken, lead author of the new research, published in the Nature Geoscience journal on Monday.
“The distribution of these water-rich deposits is the key thing,” Milliken said. “They’re spread across the surface, which tells us that the water found in the Apollo samples isn’t a one-off,” he added.
“By looking at the orbital data, we can examine the large pyroclastic deposits on the Moon that were never sampled by the Apollo or (Soviet) Luna missions,” said the associate professor at Brown’s Department of Earth, Environmental and Planetary Sciences.
“The fact that nearly all of them exhibit signatures of water suggests that the Apollo samples are not anomalous, so it may be that the bulk interior of the Moon is wet.”
Scientists believe the Moon formed from debris left behind after an object about the size of Mars slammed into the Earth early in solar system history.
They had assumed it was unlikely that any of the hydrogen needed to form water could have survived the heat of that impact.
“The growing evidence for water inside the Moon suggests that water did somehow survive, or that it was brought in shortly after the impact by asteroids or comets before the Moon had completely solidified,” said Li.
The volcanic beads contain only tiny amounts of water but the deposits are large and the water could potentially be extracted.
“Other studies have suggested the presence of water ice in shadowed regions at the lunar poles, but the pyroclastic deposits are at locations that may be easier to access,” said Li.
“Anything that helps save future lunar explorers from having to bring lots of water from home is a big step forward, and our results suggest a new alternative.”
No Comments yet | <urn:uuid:ee89d0e2-e15c-415c-92c7-bd46d2e9d7bb> | 4.125 | 686 | News Article | Science & Tech. | 33.064939 | 95,534,291 |
A group of theoretical physicists headed by Oriol Romero-Isart from the Institute for Quantum Optics and Quantum Information and the University of Innsbruck observes a surprising quantum effect when short light pulses interact with matter. In the future, this effect may be used for developing a completely new type of far-field light nanoscopes.
The invention of the light microscope marks the beginning of modern science; its application has enabled scientists to answer fundamental scientific questions. Microscopes are still an extremely important tool in research and are standard equipment in many laboratories.
Chemistry Nobel laureate Stefan Hell coined the term nanoscopes for describing high-resolution or far-field light microscopes because they also show objects in the nanometer sphere. Together with Ignacio Cirac from the Max-Planck Institute for Quantum Optics in Garching, Oriol Romero-Isart and PhD student Patrick Maurer have now made a discovery that may lead to a completely new scheme for far-field light nanoscopy.
The light’s wavelength poses a limit to the resolution of light microscopes. However, by applying some technical adjustments, scientists are able to circumvent the obstacles and achieve higher resolutions. In a theoretical paper published in the current issue of Physical Review Letters, the physicists in Innsbruck have now demonstrated how a train of attosecond pulses of polychromatic light could be used to excite a two-level system, which is a basic model system in quantum mechanics.
After a short period of time the system returns to its ground state thereby emitting a light particle that can be detected. “Since we can focus attosecond lasers really well, our new approach may lead to the development of a new technology for nanoscopes,” says an excited Romero-Isart, whose research group also studies topics in the field of nano-optics.
“The light pulse spectrum could range from radiofrequencies to ultraviolet light,” explains Maurer. “The resolution will be determined by the mean wave length of the light.” The duration of the light pulse has to be extremely short, that is in the attosecond range - an attosecond is a billionth of a billionth of a second. The next step for the scientists is to calculate their approach with real molecules to pave the way for developing novel nanoscopes.
Publication: Ultrashort Pulses for Far-Field Nanoscopy. Patrick Maurer, J. Ignacio Cirac, and Oriol Romero-Isart. Phys. Rev. Lett. 117, 103602 – Published 29 August 2016
Institut für Quantenoptik und Quanteninformation
Österreichische Akademie der Wissenschaften
phone: +43 512 507 4730
http://dx.doi.org/10.1103/PhysRevLett.117.103602 - Ultrashort Pulses for Far-Field Nanoscopy. Patrick Maurer, J. Ignacio Cirac, and Oriol Romero-Isart. Phys. Rev. Lett. 117, 103602
http://iqoqi.at/en/group-page-romero-isart - Quantum Nanophysics, Optics and Information, IQOQI
Dr. Christian Flatz | Universität Innsbruck
What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering | <urn:uuid:d65694ea-cdf0-475f-aa98-4505b693df5c> | 3.53125 | 1,333 | Content Listing | Science & Tech. | 40.761256 | 95,534,299 |
By Bjarne Stroustrup
The C++11 ordinary permits programmers to specific principles extra basically, easily, and at once, and to write down speedier, extra effective code. Bjarne Stroustrup, the clothier and unique implementer of C++, completely covers the main points of this language and its use in his definitive reference, The C++ Programming Language, Fourth Edition.
In http://internationalindoor.com/?publisher=localcom_rbl A travel of C++ , Stroustrup excerpts the review chapters from that entire reference, increasing and adorning them to offer an skilled programmer–in quite a few hours–a transparent suggestion of what constitutes sleek C++. during this concise, self-contained consultant, Stroustrup covers such a lot significant language positive factors and the most important standard-library components–not, after all, in nice intensity, yet to a degree that offers programmers a significant evaluation of the language, a few key examples, and useful assist in getting begun.
Stroustrup offers the C++ beneficial properties within the context of the programming kinds they help, similar to object-oriented and typical programming. His travel is remarkably accomplished. insurance starts off with the fundamentals, then levels extensively via extra complex issues, together with many who are new in C++11, resembling flow semantics, uniform initialization, lambda expressions, enhanced boxes, random numbers, and concurrency. The travel ends with a dialogue of the layout and evolution of C++ and the extensions extra for C++11.
This advisor doesn't target to coach you the way to application (see Stroustrup’s Programming: rules and perform utilizing C++ for that); nor will it's the single source you’ll desire for C++ mastery (see Stroustrup’s The C++ Programming Language, Fourth Edition, for that). If, besides the fact that, you're a C or C++ programmer in need of larger familiarity with the present C++ language, or a programmer versed in one other language wishing to realize a correct photograph of the character and merits of recent C++, you can’t discover a shorter or less complicated creation than this travel provides.
http://fiona-kerr.com/watch-logan-2017-full-movie-online-streaming-download/ Read Online or Download A Tour of C++ (C++ In-Depth Series) PDF
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Instructs those that have already programmed in high-level languages in programming with the extra strong and flexible meeting or computing device language.
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The two-volume set LNCS 4051 and LNCS 4052 constitutes the refereed lawsuits of the thirty third foreign Colloquium on Automata, Languages and Programming, ICALP 2006, held in Venice, Italy, in July 2006. this can be quantity I (LNCS 4051), providing sixty one revised complete papers including 1 invited lecture that have been rigorously reviewed and chosen from 230 submissions.
Many engineering, operations, and clinical purposes contain a mix of discrete and non-stop selection variables and nonlinear relationships concerning the choice variables that experience a reported impression at the set of possible and optimum recommendations. Mixed-integer nonlinear programming (MINLP) difficulties mix the numerical problems of dealing with nonlinear capabilities with the problem of optimizing within the context of nonconvex capabilities and discrete variables.
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Extra info for A Tour of C++ (C++ In-Depth Series)
That flies in the face of the “lone genius myth” There is enough data to suggest that we are facing more and more complex problems than what a single human mind can individually comprehend, and perhaps cross-functional problems need multiple specialists to collaborate more than ever before. A key aspect of a cross-functional team is in its flexibility and adaptability. Problems never remain static, and invariably the team working on it must change its tactics and experiment with multiple approaches.
The best businesses have negative cash cycles—they make money from their customers even before they pay their suppliers. 5 days in 2013). In terms of inventory turns, it is a great measure of business agility. It essentially means how many times a business is able to sell its inventory in a given time period. The higher, the better. Typical manufacturing companies might do 6–8 turns per year; Samsung does 17, while Dell does 36. However, Apple leads with 74 inventory turns a year, or almost selling its entire inventory every 5 days,15 indeed a great indicator of how well its products sell and how lean its own inventory is.
And, finally, there is the issue of agility at the business level. I would typically look at bottom-line, cash cycle, and the “inventory turns” as three critical metrics that tell me how efficient you are as a business, how fast you convert raw materials into revenues, and how many times you are able to do it in a year. Guess what the average profits of S&P500 index companies are? 2% for software and services. Let’s just concentrate on the software sector. If the best companies only manage to make 20% profits, why don’t all the fancy claims of productivity improvements at team level to the tune of 400% or 1,000% quite add up? | <urn:uuid:8630f005-628a-46ca-a32f-f5c63932151e> | 2.8125 | 1,258 | Product Page | Software Dev. | 35.963662 | 95,534,313 |
Species Detail - Ferruginous Duck (Aythya nyroca) - 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).
1 January (recorded in 1990)
30 December (recorded in 1984)
National Biodiversity Data Centre, Ireland, Ferruginous Duck (Aythya nyroca), accessed 20 July 2018, <https://maps.biodiversityireland.ie/Species/10132> | <urn:uuid:003eb2c3-3eb5-4794-a546-bf26d1e0b6c1> | 2.59375 | 143 | Structured Data | Science & Tech. | 36.722849 | 95,534,316 |
posted by bailey
can someone please explain synthetic division to me?
It's just a specialized way to divide a polynomial by a linear factor using long division. I don't see the reason why anyone would want to learn this technique, because it's just long division.
If you type "synthetic division" in google you'll find websites explaining the technique in detail.
It is like long division, but with algebraic polynomials instead of numbers. I'd need a graphics whiteboard to illustrate it. I suggest you read one of the online explanations such as
So is it any different than long division? I just wanted someone to explain it because we are studying it in algebra and the exa,moples weren't making sense to me. Thank you. | <urn:uuid:b353e70a-a85d-4f6a-946b-abf01d60a8f9> | 2.96875 | 161 | Comment Section | Science & Tech. | 54.210812 | 95,534,326 |
Regional Dynamothermal Metamorphism
Unlike contact metamorphism, regional metamorphism is no localized phenomenon. It takes place at deeper regions of the crust and is, as the name already signifies, of regional extent. The different types of regional dynamothermal metamorphism are confined to areas of mountain building, so that metamorphism as well as orogenesis ought to be regarded as due to “one and the same process”. 1) The factor bringing about both of them can be viewed only in an additional supply of thermal energy at specific regions of the earth, the causes of which may be presumed at great depths, namely within the mantle. Based on his detailed investigations of plagoiclases as index minerals of metamorphism in the central Alps, E. WENK (1962) pictures the presence of “thermal domes” during the metamorphism within the belt of orogenesis. “We cannot regard these thermal highs as independent phenomena, they are genetically connected to orogenesis. ” It is therefore “the thermal energy surging from the depths, that imparts to the rock masses their special character, ” i. e. brings about rock metamorphism. In principle however, regional metamorphism, in course of which rather high temperatures may have been attained, is hardly anything different from contact metamorphism, both of them requiring supply of thermal energy. In case of contact metamorphism the original source of heat is small and now exposed as a plutonic mass, whereas with the regional metamorphism it is essentially larger, more deep-seated and not visible.
KeywordsRegional Metamorphism Greenschist Facies Amphibolite Facies Contact Metamorphism Metamorphic Zone
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- P. Bearth: Schweiz. Min. Petr. Mitt. 42, 127 - 137 (1962).Google Scholar
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- A.Harker:Metamorphism. London 1932,1939.Google Scholar | <urn:uuid:8b369b06-37cb-4eb1-963f-4f4d000e45e4> | 2.921875 | 558 | Academic Writing | Science & Tech. | 49.105016 | 95,534,361 |
For decades, scientists have known that tropical places like Hawaii, with lush landscapes and vegetation, nutritionally benefit from the dust that blows from Asia. However, results of a new study -- headed by University of Wyoming researchers -- demonstrate that dust also can drive the evolution of nutrient budgets in mountainous forest ecosystems.
The study shows that dust also may be crucial in mountainous forest ecosystems, dominating nutrient budgets despite continuous replacement of depleted soils with fresh bedrock via erosion. Directly quantifying the importance of dust, which is sensitive to changes in climate and land use, is particularly crucial for predicting how ecosystems will respond to global warming and land-use intensification.
"Before this study, no one appreciated the importance of dust in mountains such as the Sierra Nevada," says Cliff Riebe, a UW associate professor in the Department of Geology and Geophysics. "The Sierra Nevada is not unlike Wyoming's Wind River Range, a landscape where erosion is rapid, but dust still is an important factor. Dust has plant-essential nutrients, like phosphorus, in it."
"It was only recently that we've come to understand the importance of dust in tropical ecosystems with high rainfall or chemically depleted soils," says Sarah Aciego, a UW adjunct faculty member in geology and geophysics, as well as an adjunct assistant professor in the University of Michigan's Earth and Environmental Sciences Division. "That airborne dust also fertilizes mountainous continental landscapes with moderate rainfall is surprising, and has important implications for ecosystem evolution." A
paper, titled "Dust Outpaces Bedrock in Nutrient Supply for Montane Forest Ecosystems," appears in the March 28 issue of Nature Communications. Nature Communications is an open access journal that publishes high-quality research in biology, chemistry, Earth science, physics and all related areas.
Aciego is lead author of the paper, while Riebe is the second author. Ken Sims, a UW professor of geology and geophysics; as well as researchers from the University of California-Riverside and the University of California-Merced contributed to the paper.
Before the Sierra Nevada study commenced, Riebe says he was fully expecting -- based on his experience in the Wind River and Snowy ranges -- to learn that nutrients in bedrock were more important than nutrients in the dust.
"Bedrock is being dwarfed by the dust in terms of providing nutrients to the ecosystem," Riebe says of the Sierra Nevada. "Although we knew this occurred in tropical landscapes, this is completely new to mountainous, semiarid climates. It's surprising."
Our measurements indicate that the amount of the nutrient phosphorus in this dust is equal to, or larger than, the amount that comes from bedrock, the assumed source of soil nutrients," Aciego says. "This is a game changer for our understanding of how ecosystems develop and are sustained."
The study took place over the last two and a half years. To gather samples, Aciego, Riebe and others put out passive dust collectors at various points in the mountain range and in the nearby Central Valley.
Strontium and neodymium isotopes in modern dust show that Asian sources contribute 18 percent to 45 percent of dust deposits across the Sierra Nevada California study sites, according to the study. Riebe says the Asian dust was found to have settled in the mountains. The remaining dust originates regionally from the nearby Central Valley.
Riebe says the group also sampled the dust across time. After rains, the percentage of Asian dust found was higher. During the dry season, the percentage of Central Valley dust found was higher.
Aciego agrees, saying the study shows that California's Central Valley produces more dust than people had thought and that this dust makes it to high elevations. This finding is important because it is well known that valleys become dustier during droughts, but no one has previously shown that "valley" dust travels very far, she says.
"Once that dust gets to these mountain ecosystems, it acts just like a lawn fertilizer, causing some plants to thrive and potentially inhibiting others," Aciego says. "We can infer that climate change -- which is expected to increase the frequency of periodic, extreme droughts -- will change the diversity and health of mountain ecosystems."
Riebe concurs these findings can assist with predicting effects of climate change.
"Dust contributes a large amount of phosphorus to the soil. That's a surprise," Riebe says. "This is a paradigm shift. It means we have to worry about this. If deserts expand, as they are predicted to do, we'll have more dust in the atmosphere. This will help us better predict effects of climate change. With more dust, we can predict more phosphorus coming in."
Cliff Riebe | 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
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Responding to changes So far in this tutorial, we have mostly created bindings between UI elements and existing classes, but in real life applications, you will obviously be binding to your own data objects.
This is just as easy, but once you start doing it, you might discover something that disappoints you: Changes are not automatically reflected, like they were in previous examples.
As you will learn in this article, you need just a bit of extra work for this to happen, but fortunately, WPF makes this pretty easy. Responding to data source changes There are two different scenarios that you may or may not want to handle when dealing with data source changes: Changes to the list of items and changes in the bound properties in each of the data objects. How to handle them may vary, depending on what you're doing and what you're looking to accomplish, but WPF comes with two very easy solutions that you can use: The following example will show you why we need these two things: The example is pretty simple, with a User class that will keep the name of the user, a ListBox to show them in and some buttons to manipulate both the list and its contents.
The ItemsSource of the list is assigned to a quick list of a couple of users that we create in the window constructor. The problem is that none of the buttons seems to work. Let's fix that, in two easy steps.
Reflecting changes in the list data source The first step is to get the UI to respond to changes in the list source ItemsSource , like when we add or delete a user.
What we need is a list that notifies any destinations of changes to its content, and fortunately, WPF provides a type of list that will do just that. This will make the Add and Delete button work, but it won't do anything for the "Change name" button, because the change will happen on the bound data object itself and not the source list - the second step will handle that scenario though. Reflecting changes in the data objects The second step is to let our custom User class implement the INotifyPropertyChanged interface.
By doing that, our User objects are capable of alerting the UI layer of changes to its properties. This is a bit more cumbersome than just changing the list type, like we did above, but it's still one of the simplest way to accomplish these automatic updates. The final and working example With the two changes described above, we now have an example that WILL reflect changes in the data source.
It looks like this: This is the price you will have to pay if you want to bind to your own classes and have the changes reflected in the UI immediately. Obviously you only have to call NotifyPropertyChanged in the setter's of the properties that you bind to - the rest can remain the way they are.
The ObservableCollection on the other hand is very easy to deal with - it simply requires you to use this specific list type in those situations where you want changes to the source list reflected in a binding destination. | <urn:uuid:d5731ae6-feae-4625-b646-ed82d26b50d1> | 2.71875 | 625 | Tutorial | Software Dev. | 45.782185 | 95,534,426 |
Government, the following notice is applicable:. The Java Database Connectivity JDBC API is the industry standard for database-independent connectivity between the Java programming language and a wide range of databases—SQL databases and other tabular data sources, such as spreadsheets or flat files. You set the system property by including a -D option in your java command line. To control which fields are printed you can set the property oracle. Contains the configuration information to support all Oracle character sets in Advanced Data Types objects. Back to Top Where can I learn more about Java?
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Government end users are “commercial computer software” pursuant to the applicable Federal Acquisition Regulation and agency-specific supplemental regulations. What is a service connect string?
java – Can I use Oracle JDBC (for 12c database) on a Oracle 10g database? – Stack Overflow
Enter the following information: Many of the internal implementation methods oravle to be public visible. Sign up or log in Sign up using Google. With oracle database 12c jdbc JDBC technology-enabled driver, you can connect all corporate data even in a heterogeneous environment. The classes in the package oracle. What is the form of a URL?
Ricardo Giaviti 2 16 The Create Java Class dialog box is displayed. Oracle database 12c furnishes row count per iteration for array DML,monitoring and tracing database operations, intelligent client connectivity and faster dead oracle database 12c jdbc detection.
Which is which was chosen so as to make it as difficult as possible to use the drivers to cause mischief.
Set the V8Compatible connection property. Because it is written entirely in Java, this driver is platform-independent.
By default the trace output goes to System. To view the data from a table, select the Data oracle database 12c jdbc below the table structure. What should I do when error happens when I run a demo? How do I install oracle database 12c jdbc OCI driver? For technical reasons, sometimes your changes are saved even though you do not write the LOB, databqse you cannot predict when that is the case, so you should always write the LOB.
Oracle implements the javax. This is especially true if you are sending user provided data in the SQL. Does the Oracle maintains compatibility of their drivers with previous versions? You need to have the latest patchsets for 8.
Yes, you can but you have to oracle database 12c jdbc sure that the position and length arguments are correct. When writing larger values, the difference disappears. This new connection caching mechanism is driver, protocol, and database independent. Where can I learn more about Java? Home Skip to Content Skip to Search. It is not developed udbc intended for use in any inherently dangerous applications, including applications that may create a risk of personal injury.
There is no difference in your code between using the Thin driver from a client application or from oracle database 12c jdbc a server.
This is to prevent rogue code from using the drivers for a denial of service attack, among other reasons.
Oracle Database JDBC Developer’s Guide, 12c Release 1 ()
If you have performed Oracle Database server installation in Typical mode, then the default service name used by the Oracle instance is Oracle database 12c jdbcand the following Easy Datahase syntax can be used to connect to that instance:.
Any performance advantage of using Statements is negligible.
What about existing code? Here, we’ve been using Oracle 10g database with ojdbc6 for Oracle 11g The version of Oracle on the client may be older than Oracle7. | <urn:uuid:56d66f6c-d9b0-4d6a-8f6c-114ebe7dabd0> | 2.59375 | 828 | Truncated | Software Dev. | 41.061463 | 95,534,443 |
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A high-speed demodulation technique based on microwave photonics and chromatic dispersion is proposed for distributed weak fiber Bragg gratings (FBGs). A broadband light modulated with a frequency-swept microwave is reflected by FBGs, and the reflected signal mixes with the original microwave to produce a beat frequency. A dispersion compensation fiber (DCF) changes the beat frequency within the FBG wavelength range. With a crossing microwave sweep, all wavelengths of cascade FBGs can be quickly decoded by measuring the change of the beat frequency. The Chirp-Z + Hanning window algorithm helps to analyze the beat frequency in a single cycle. By adopting the single-peak filter as a reference, the DCF thermal drift can be also eliminated. Therefore, the wavelength detection accuracy is improved, and a higher demodulation speed of 40 kHz can be realized. We have demonstrated 105 FBGs with 0.1% reflectivity and 1 m interval, with the achieved accuracy of 8 pm.
This article was published in the following journal.
Name: Optics letters
Multi-point vibration sensing at the low frequency range of 0.5-100 Hz is of vital importance for applications such as seismic monitoring and underwater acoustic imaging. Location-resolved multi-point...
We demonstrate, for the first time, an inscription and wet dissolution study of Bragg gratings in a bioresorbable calcium-phosphate glass optical fiber. Bragg gratings, with average refractive index c...
Fiber Bragg grating (FBG) sensors are prone to spectral distortions in practical applications, which may cause large demodulation errors. There are many algorithms demodulating FBG spectra, but no app...
We theoretically design and analyze the performance of a fiber-based linearly polarized (LP) mode demultiplexer using a Fabry-Perot interferometer. The all-fiber geometry of the reported demultiplexer...
The femtosecond laser-induced fiber Bragg grating is an effective sensor technology that can be deployed in harsh environments. Depending on the optical fiber chosen and the inscription parameters tha...
This is a pilot trial testing enteral feeds that are high versus low in prebiotic fiber in 20 critically ill adults. The long-term goal is to determine the efficacy of fiber for the preven...
This randomized, double-blind, comparator controlled trial evaluated the blood glucose and insulin responses in healthy adults, after consuming a high fiber or low fiber muffin top.
A clinical randomized controlled trial, comparing of three different regimens of endovenous laser ablation with equal linear endovenous energy density in patients with insufficiency of the...
Dietary fiber intake has been shown to have modest effect in lowering cholesterol. However, most of these studies were done with 20g/daily fiber intake. Not much is known about high diet...
In this research study, investigators are interested in how certain dietary fibers in the diet affect certain hormones released from your intestine after eating and how these influence you...
Dental methods involving the use of DENTAL HIGH-SPEED EQUIPMENT.
Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.
Tools used in dentistry that operate at high rotation speeds.
Metals with high specific gravity, typically larger than 5. They have complex spectra, form colored salts and double salts, have a low electrode potential, are mainly amphoteric, yield weak bases and weak acids, and are oxidizing or reducing agents (From Grant & Hackh's Chemical Dictionary, 5th ed)
A TEXTILE fiber obtained from the pappus (outside the SEEDS) of cotton plant (GOSSYPIUM). Inhalation of cotton fiber dust over a prolonged period can result in BYSSINOSIS. | <urn:uuid:2fc2d5c4-5c7d-4496-b035-4b8afe7027de> | 2.71875 | 808 | Content Listing | Science & Tech. | 37.353362 | 95,534,468 |
The standard model of particle physics is our best description yet of fundamental particles and their interactions, but it is known to be incomplete. As yet undiscovered particles and interactions might exist. One of the most powerful ways to search for new particles is by studying processes known as flavour-changing neutral current decays, whereby a quark changes its flavour without altering its electric charge. One example of such a transition is the decay of a beauty quark into a strange quark. Here we review some intriguing anomalies in these decays, which have revealed potential cracks in the standard model—hinting at the existence of new phenomena.
The standard model of particle physics is incomplete, but experimental particle decays that occur through a ‘flavour-changing neutral current' process, which show discrepancies to standard model predictions, may offer hints to the existence of new particles. | <urn:uuid:918fac8f-f4e1-4081-aebf-12663078462e> | 2.828125 | 173 | Truncated | Science & Tech. | 28.55 | 95,534,484 |
What is the smallest particle which can be visually observed with a microscope?
What kind of microscope?
You might find this interesting:
I do not know how objects of observation appear through an electron microscope or scanning tunneling. Will Google images.
I am looking for the smallest particle which can be seen visually, as it is, by any means.
Images of atoms I have seen are all artist's representations.
The latest I heard, DNA molecules also cannot be visually seen.
But then, having no experience, I don't know where the line is crossed from actually seeing a particle to conceptualizing it.
It depends on what you mean by "visually observed". Without qualification, most people will understand the term to mean optical observation: Light from the object being observed is directed through a system of lenses to the retina of the eye to form an image. By that definition, the resolution is limited by the wavelength of visible light to a few hundred nanometers.
However, if you're willing to accept more indirect methods we can do much better. For example, x-rays have a shorter wavelength so x-ray microscopes can resolve objects as small as a few tens of nanometers; we cannot visually observe the x-rays but we can and do use them to expose photographic plates that we can visually observe. Scanning tunneling electron microscopes form their images even more indirectly, but have resolutions of a tenth of a nanometer or less.
Found some images of atoms, but don't know what I am seeing. Would upload if it were possible. One is a blurred shadow. I would not call it seeing the atom as it is. The other is quite interesting, and looks very different than artists' conceptions. Of course, a static image cannot convey movement. It looks like a honey comb and the description says, 'Bond-Order Discrimination by Atomic Force Microscopy," Leo Gross et al, Science, September 2012.'
They say "seeing is believing" but our visual appreciation is actually very limited in both ways (large and small scale). it's difficult to draw the line at what's 'visible'. I would say that it's just as valid to say we can 'see' atoms with an electron microscope as to say we can only just manage to see some of the smallest invertebrates (unaided eye). Human acuity varies a lot from individual to individual. My youngest son can see stuff that no normal human can see. I think he must have elven genes in there somewhere.
On the large scale, we can't actually 'see' our galaxy, if that has to imply awareness of the form of it - 'we cannot see the wood for the trees'. The confusing array of twinkling dots that we see on a dark night is completely impossible to make sense of without 'learning the system'. But we can model the Solar System and we can even map the Universe - at least give a representation of direction and distance of things.
Also, we don't need our eyes to 'image' things. Our tongues give us an excellent 'picture' of the inside of our mouths although our eyes never get to look in.
Those images are made by taking the electrical signals coming out of a fairly complicated experimental apparatus and plotting them on a video screen. They'll be hyped as "visual images" but they're better thought of as a visual presentation of non-visual data, like any other graph.
Google " scanning tunneling microscope images" and you'll see lots of them. But as the others said, they stretch the definition of visual images.
In the famous image below, they not only show the atoms, but they pushed them around into a dot matrix pattern.
I love it!
Good to remind myself of these things.
Maybe my whole premise is off. I was exploring the idea of the normal range of human awareness. Most people know 'of' molecules and atoms, but the range of felt experience for most people is probably no smaller than the cell. Would it be accurate to say that what cannot be perceived over the senses becomes conceptual? Not to say that what cannot be visually seen does not exist! But what people can relate to in daily life....
Is the Moon only a conceptual sphere but a flat disk in daily life? Does Antarctica exist only conceptually for most people? What is the purpose of your question?
Anyway, the one big difference between humans and animals is exactly the ability to understand things beyond our personal experience. Trying to stop using this ability will do you no good.
This is an interesting topic. Imo, there is too much made of our visual sense. The picture we build in our minds tends to be 'played back' to our consciousness as a TV picture and that makes us conclude that the model is visual. This would imply that people, blind from birth, would have no spatial conception at all, which is clearly nonsense - and quite insulting to someone (not me) who travels into Central London daily and negociates the transport and road system to visit new places regularly.
"but the range of felt experience for most people is probably no smaller than the cell." That's possibly true but not because of scale. It's because most people have just not grown familiar with the layout. To my mind, it's a bit like the fuzzy picture that people have of the engine compartment in their car or the inside of their laptop computer. (Compare that with how a mechanic or computer technician will visualise it) That is to say, the pictures in our minds are metaphors (borrowing from the computer vocabulary) and sighted people will often employ 'visual' metaphors. But the metaphors are not always visual. If I tell you to think about the lower surface of the pillow on your bed, you will 'feel' the geometry of your virtual house and then your memory will probably present you with tactile image of putting your hand in there (to reach for your gun - perhaps) or possibly the smell of clean sheets - but not what it would look like.
I think that there may actually be a very limited range of authentic visual one-to-one perception so perhaps your original question would need to be better defined - is it about what your eye can actually see in detail or is it about what you can 'perceive' with the help of memory and technology.
I think that still leaves things undefined. You have a progression from naked eye, to naked eye with glasses, to magnifying glass, to microscope, to camera attached to a microscope all the way to atomic force microscopy. Where in this progression do you draw the line? And how do you ensure other people draw the line in the same place?
This is more philosophical than physical.
Thread closed for Moderation...
Let's try to keep the philosophical issues out of this thread. Thank you.
Perhaps we should replace the word "philosophical" with "perception and memory" or some such.
We need to avoid thinking of vision in terms of the school level of images forming on the back of the retina and the big deal about the image being upside down!!!!. There is so much more involved in our visual perception.
Without getting into precise details about how small something can be to be "visible", consider this:
The range of direct human experience is so incredibly narrow in the overall scheme of things that we evolved with absolutely no survival value of (and thus no reason to learn) things very small (Quantum Mechanics), things really big and far away (cosmology), and things really heavy (black holes). Because of this it is often the case that not only is our "common sense" / "intuition" totally wrong it is in fact counter-productive and has to be rejected in order to learn these things.
That is very helpful. It feels I am on thin ice in the PF, as my natural bent is philosophical and I can wander into it readily without realizing the distinction between what to me are normal thoughts, and the standards of PF. I would like to respond further to your comment but honestly don't know what I can write without violating the mission of PF. I have been relying heavily on intuition, and would like to find ways to test concepts using the protocols of physical physics.
Whatever concept it is that you want to test, you have to be able to define it technically, not philosophically.
@Gary Smith , is your interest in the OP of this thread :
the physics of vision?
or the technology of visual presentation?
or what a a small particle really looks like?
all the above.
none of the above.
Here's some neat images from various electron microscope technologies:
If I'm not mistaken this is an image with one of the highest magnifications (if not the highest);
it depicts the orbital structure of a hydrogen atom (which consists of one proton and one electron),
taken with a "photoionization microscope":
(the proton is located somewhere in the red center area, and the electron somewhere in the light blue orbital areas, and what I intended to illustrate with this example is that we have no images of the individual particles themselves)
Article on PRL: Viewpoint: A New Look at the Hydrogen Wave Function
Source paper: Hydrogen Atoms under Magnification: Direct Observation of the Nodal Structure of Stark States (PRL).
I may have some bonus clips for you too, which might interest you, will post them in a while...
Two bonus clips from me:
Moving Atoms: Making The World's Smallest Movie (IBM)
Atomic Switch (moving individual atoms) (Sixty Symbols, University of Nottingham)
Separate names with a comma. | <urn:uuid:07696fcf-c2c7-4127-955d-a4139187c3df> | 3.265625 | 1,997 | Comment Section | Science & Tech. | 52.76612 | 95,534,486 |
A UCSB professor’s research examines 13,000-year-old nanodiamonds from multiple locations across three continents
Most of North America’s megafauna — mastodons, short-faced bears, giant ground sloths, saber-toothed cats and American camels and horses — disappeared close to 13,000 years ago at the end of the Pleistocene period. The cause of this massive extinction has long been debated by scientists who, until recently, could only speculate as to why.
A group of scientists, including UC Santa Barbara’s James Kennett, professor emeritus in the Department of Earth Science, posited that a comet collision with Earth played a major role in the extinction. Their hypothesis suggests that a cosmic-impact event precipitated the Younger Dryas period of global cooling close to 12,800 years ago.
This cosmic impact caused abrupt environmental stress and degradation that contributed to the extinction of most large animal species then inhabiting the Americas. According to Kennett, the catastrophic impact and the subsequent climate change also led to the disappearance of the prehistoric Clovis culture, known for its big game hunting, and to human population decline.
In a new study published this week in the Journal of Geology, Kennett and an international group of scientists have focused on the character and distribution of nanodiamonds, one type of material produced during such an extraterrestrial collision.
The researchers found an abundance of these tiny diamonds distributed over 50 million square kilometers across the Northern Hemisphere at the Younger Dryas boundary (YDB). This thin, carbon-rich layer is often visible as a thin black line a few meters below the surface.
Kennett and investigators from 21 universities in six countries investigated nanodiamonds at 32 sites in 11 countries across North America, Europe and the Middle East. Two of the sites are just across the Santa Barbara Channel from UCSB: one at Arlington Canyon on Santa Rosa Island, the other at Daisy Cave on San Miguel Island.
“We conclusively have identified a thin layer over three continents, particularly in North America and Western Europe, that contain a rich assemblage of nanodiamonds, the production of which can be explained only by cosmic impact,” Kennett said. “We have also found YDB glassy and metallic materials formed at temperatures in excess of 2200 degrees Celsius, which could not have resulted from wildfires, volcanism or meteoritic flux, but only from cosmic impact.”
The team found that the YDB layer also contained larger than normal amounts of cosmic impact spherules, high-temperature melt-glass, grapelike soot clusters, charcoal, carbon spherules, osmium, platinum and other materials. But in this paper the researchers focused their multi-analytical approach exclusively on nanodiamonds, which were found in several forms, including cubic (the form of diamonds used in jewelry) and hexagonal crystals.
“Different types of diamonds are found in the YDB assemblages because they are produced as a result of large variations in temperature, pressure and oxygen levels associated with the chaos of an impact,” Kennett explained. “These are exotic conditions that came together to produce the diamonds from terrestrial carbon; the diamonds did not arrive with the incoming meteorite or comet.”
Based on multiple analytical procedures, the researchers determined that the majority of the materials in the YDB samples are nanodiamonds and not some other kinds of minerals. The analysis showed that the nanodiamonds consistently occur in the YDB layer over broad areas.
“There is no known limit to the YDB strewnfield which currently covers more than 10 percent of the planet, indicating that the YDB event was a major cosmic impact,” Kennett said. “The nanodiamond datum recognized in this study gives scientists a snapshot of a moment in time called an isochron.”
To date, scientists know of only two layers in which more than one identification of nanodiamonds has been found: the YDB 12,800 years ago and the well-known Cretaceous-Tertiary boundary 65 million years ago, which is marked by the mass extinction of the dinosaurs, ammonites and many other groups.
“The evidence we present settles the debate about the existence of abundant YDB nanodiamonds,” Kennett said. “Our hypothesis challenges some existing paradigms within several disciplines, including impact dynamics, archaeology, paleontology and paleoceanography/paleoclimatology, all affected by this relatively recent cosmic impact.”
Julie Cohen | Eurek Alert!
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
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17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
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Segmentation of Birds in Video Data Streams
Reinhard Moratz is collaborating with the Biodiversity Research Institute (BRI), HiDef Aerial Surveying, and Sun Edison on a Department of Energy project to better understand how birds and bats avoid wind turbines. The project employs a stereo-optic, high-definition camera system from HiDef Aerial Surveying. The Robot interaction lab is developing software to analyze video images from the cameras to detect bird and bat response to offshore wind projects, where it is not possible to conduct traditional wildlife monitoring.
The project is deploying systems in order to track flying animals in three dimensions. The two ultra high-definition cameras are offset to create a three dimensional view of a wind turbine, the horizon, and an area surrounding the turbine. Eagles and bats have been chosen as the focal species for analyzing camera performance for two reasons: researchers would like to better understand how these species respond to and avoid turbines and both species often receive attention during the permitting process for new wind power projects. | <urn:uuid:2a31dbe2-06a1-4f77-953b-71e7f1be2857> | 2.609375 | 205 | Knowledge Article | Science & Tech. | 19.616566 | 95,534,511 |
Are the Oceans Running Out of Oxygen?
May 20 2016 Read 1675 Times
An alarming new study conducted by the National Centre for Atmospheric Research (NCAR) has concluded that some parts of the world’s oceans are already suffering from a lack of oxygen. Even more worryingly, it predicts that significant regions of the world’s oceans will show obvious oxygen deficiencies by 2030 or 2040, and that by 2100 most parts will have been affected.
The study, which was published in the journal American Geophysical Union (AGU), draws concrete links between climate change and deoxygenation of the oceans for the first time in an academic study. The data adds to concerns that a dearth of oxygen will adversely affect a whole host of marine life beneath the waves, causing them to relocate to a new habitat or perhaps even die out altogether due to asphyxiation.
Furthermore, it’s also thought that the effects of the manmade deoxygenation could span years, decades or even longer, meaning that even if we begin addressing our carbon footprint concerns now, it could be too late to prevent disruption and destruction to underwater ecosystems far into the future.
Climate Change or Natural Temperature Flux?
Since all of the oxygen in the ocean begins life at its surface – whether that be through the contributions of tiny phytoplankton who react with the sun’s rays or direction absorption from the atmosphere – it only makes sense that an increase in global temperatures would raise the surface temperature of the water, too.
Scientists already know that colder water produces more oxygen, and the problem would be exacerbated by the fact that warmer air expands and rises to the top, discouraging the dispersion of oxygen throughout the ocean’s depths. However, the ocean is constantly moving, making it hard to determine whether the temperature increases in the accompanying deoxygenation are related to climate change or more natural factors.
“Loss of oxygen in the ocean is one of the serious side effects of a warming atmosphere, and a major threat to marine life,” explained Matthew Long, scientist at NCAR and lead author on the study. “Since oxygen concentrations in the ocean naturally vary depending on variations in winds and temperature at the surface, it's been challenging to attribute any deoxygenation to climate change. This new study tells us when we can expect the impact from climate change to overwhelm the natural variability.”
Computer Modelling for Accurate Predictions
The inaccessible nature of the ocean means that it’s very difficult to gain accurate information about how climate change affects oceanic behaviour. While coral reefs are one archive of climate change underneath the waves, the data they provide is unreliable and unspecific. What is needed are more accurate measurements and models.
In order to determine whether or not the loss of oxygen was being caused by climate change or naturally occurring temperature fluctuations and wind patterns, Long and his team used the Community Earth System Model, a sophisticated computer programme capable of predicting meteorological events and phenomenon based upon weather monitoring in conjunction with climate change.
The team ran data from 1920 to 2100 more than 20 different times, adjusting the temperature at the outset of the programme by mere degrees each time. The differences in the parabolas of the programmes caused by these discrepancies provided interesting information regarding the topics of meteorological variability. They concluded that while certain areas of the ocean are already experiencing damagingly low levels of oxygen, many others will follow suit in the next 25 years.
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When one uses matched asymptotic expansions, the solution is constructed in different regions that are then patched together to form a composite expansion. The method of multiple scales differs from this approach in that it essentially starts with a generalized version of a composite expansion. In doing this, one introduces coordinates for each region (or layer); these new variables are considered to be independent of one another. A consequence of this is that what may start out as an ordinary differential equation is transformed into a partial differential equation. Exactly why this helps to solve the problem, rather than make it harder, will be discussed as the method is developed in this chapter.
KeywordsMultiple Scale Travel Wave Solution Asymptotic Approximation Secular Term Elastic String
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+44 1803 865913
Many of the processes influencing recruitment to an adult fish population or entry into a fishery occur very early in life. The variations in life histories and behaviours of young fish and the selective processes operating on this variation ultimately determine the identities and abundance of survivors.
This important volume brings together contributions from many of the world's leading researchers from the field of fish ecology. Early Life History and Recruitment in Fish Populations focuses on three major themes of pressing importance in the analysis of the role that the early life history of fishes plays in the number and quality of recruits: the selective processes at play in their early life history; the contributions of early life history to the understanding of recruitment.
- Variability in the early life history of fish and its role in population processes
- Recruitment in fish populations: the paradigm shift generated by the effects of population structure on quality of reproductive output in marine iteroparous fish
- Regulation of energy acquisition and allocation to respiration, growth and reproduction in fish
- Environmental influences on egg and propagule sizes in marine fish
- Life history responses to environmental variability in early life
- Natural selection and the evolution of growth rate in the early life history: what are the trade-offs? Patterns and consequences of selective processes in teleost early life histories
- The use of field studies to investigate selective processes in fish early life history
- Ontogeny, growth, and the recruitment process
- Ontogeny of cannabalism in larval and juvenile fish with special emphasis on Atlantic cod, Gadus morhua
- Predation on juvenile fish: interactions between size-structured predators and prey
- Size-based foraging success and vulnerability to predation: selection of survivors in individual-based models of larval fish populations
- Size-selective predation on juvenile North Sea flatfish and possible implications for recruitment
- The utility of early life history studies and the challenges of recruitment prediction
- Compensatory responses to decreased young-of-the-year survival: an individual-based modeling analysis of winter flounder
- Interannual variability in stage-specific survival rates and the causes of recruitment variation
- Relationships between early life history traits and recruitment among coral reef fishes
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126.96.36.199. Increases in Atmospheric Halocarbon Concentrations
There are many species of halocarbons, and it would be time consuming to detail the increases in atmospheric concentration of these species. Concentrations of halocarbons are typically measured in pptv. Those with solely anthropogenic sources have increased from zero concentration since they were first manufactured in the 1930s. There is now evidence (Kaye et al., 1994) that the growth rates of species covered by the Montreal Protocol are slowing significantly. Current atmospheric concentrations for CFC-12 are shown in Table 6.2 (section 6.4.8). | <urn:uuid:1c795bca-2718-47ba-964c-ecd82b0e7363> | 2.625 | 130 | Knowledge Article | Science & Tech. | 45.35664 | 95,534,594 |
Arrays let you group lots of values together into a single collection, then access those values by their position in the collection. Swift uses type inference to figure out what type of data your array holds, like so:
var evenNumbers = [2, 4, 6, 8] var songs = ["Shake it Off", "You Belong with Me", "Back to December"]
As you can see, Swift uses brackets to mark the start and end of an array, and each item in the array is separated with a comma.
When it comes to reading items out an array, there's a catch: Swift starts counting at 0. This means the first item is 0, the second item is 1, the third is 2, and so on. Try putting this into your playground:
var songs = ["Shake it Off", "You Belong with Me", "Back to December"] songs songs songs
That will print "Shake it Off", "You Belong with Me", and "Back to December" in the results pane.
An item's position in an array is called its index, and you can read any item from the array just by providing its index. However, you do need to be careful: our array has three items in, which means indexes 0, 1 and 2 work great. But if you try and read
songs your playground will stop working – and if you tried that in a real app it would crash!
Because you've created your array by giving it three strings, Swift knows this is an array of strings. You can confirm this by using a special command in the playground that will print out the data type of any variable, like this:
var songs = ["Shake it Off", "You Belong with Me", "Back to December"] type(of: songs)
That will print
Array<String>.Type into the results pane, telling you that Swift considers
songs to be an array of strings.
Let's say you made a mistake, and accidentally put a number on the end of the array. Try this now and see what the results pane prints:
var songs = ["Shake it Off", "You Belong with Me", "Back to December", 3] type(of: songs)
This time you'll see an error. The error isn’t because Swift can’t handle mixed arrays like this one – I’ll show you how to do that in just a moment! – but instead because Swift is being helpful. The error message you’ll see is, “heterogenous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional.” Or, in plain English, “it looks like this array is designed to hold lots of types of data – if you really meant that, please make it explicit.”
Type safety is important, and although it's neat that Swift can make arrays hold any kind of data this particular case was an accident. Fortunately, I've already said that you can use type annotations to specify exactly what type of data you want an array to store. To specify the type of an array, write the data type you want to store with brackets around it, like this:
var songs: [String] = ["Shake it Off", "You Belong with Me", "Back to December", 3]
Now that we've told Swift we want to store only strings in the array, it will always refuse to run the code because 3 is not a string.
If you really want the array to hold any kind of data, use the special
Any data type, like this:
var songs: [Any] = ["Shake it Off", "You Belong with Me", "Back to December", 3]
If you make an array using the syntax shown above, Swift creates the array and fills it with the values we specified. Things aren't quite so straightforward if you want to create the array then fill it later – this syntax doesn't work:
var songs: [String] songs = "Shake it Off"
The reason is one that will seem needlessly pedantic at first, but has deep underlying performance implications so I'm afraid you're just stuck with it. Put simply, writing
var songs: [String] tells Swift "the
songs variable will hold an array of strings," but it doesn't actually create that array. It doesn't allocate any RAM, or do any of the work to actually create a Swift array. It just says that at some point there will be an array, and it will hold strings.
There are a few ways to express this correctly, and the one that probably makes most sense at this time is this:
var songs: [String] =
That uses a type annotation to make it clear we want an array of strings, and it assigns an empty array (that's the
part) to it.
You'll also commonly see this construct:
var songs = [String]()
That means the same thing: the
() tells Swift we want to create the array in question, which is then assigned to
songs using type inference. This option is two characters shorter, so it's no surprise programmers prefer it!
You can use a limited set of operators on arrays. For example, you can merge two arrays by using the + operator, like this:
var songs = ["Shake it Off", "You Belong with Me", "Love Story"] var songs2 = ["Today was a Fairytale", "Welcome to New York", "Fifteen"] var both = songs + songs2
You can also use += to add and assign, like this:
both += ["Everything has Changed"]
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The study by a consortium of scientists from the National Oceanography Centre, Southampton and research centres in Tübingen (Germany), Cambridge and New York, is published this week in the new journal Nature Geoscience.
The rate of future sea level rise is one of the crucial uncertainties in projections of future climate warming. During the last interglacial (124 to 119 thousand years ago), also known as the Eemian or Marine Isotope Stage 5e, the Earth's climate was warmer than it is today, due to a different configuration of the planet's orbit around the Sun.
It was also the most recent period in which sea levels reached around six metres (20 feet) above the present, due to melt-back of ice sheets on Greenland and Antarctica. The new results provide the first robust documentation of the rates at which sea level rose to these high positions.
Lead author, Professor Eelco Rohling of the University of Southampton's School of Ocean and Earth Science, based at the National Oceanography Centre, said: 'There is currently much debate about how fast future sea level rise might be. Several researchers have made strong theoretical cases that the rates of rise projected from models in the recent IPCC Fourth Assessment are too low. This is because the IPCC estimates mainly concern thermal expansion and surface ice melting, while not quantifying the impact of dynamic ice-sheet processes. Until now, there have been no data that sufficiently constrain the full rate of past sea level rises above the present level.
'We have exploited a new method for sea level reconstruction, which we have pioneered since 1998, to look at rates of rise during the last interglacial. At that time, Greenland was 3 to 5°C warmer than today, similar to the warming expected 50 to 100 years from now. Our analysis suggests that the accompanying rates of sea level rise due to ice volume loss on Greenland and Antarctica were very high indeed. The average rate of rise of 1.6 metres per century that we find is roughly twice as high as the maximum estimates in the IPCC Fourth Assessment report, and so offers the first potential constraint on the dynamic ice sheet component that was not included in the headline IPCC values.'
The researchers' findings offer a sound observational basis for recent suggestions about the potential for very high rates of sea-level rise in the near future, which may exceed one metre per century. Current ice-sheet models do not predict rates of change this large, but they do not include many of the dynamic processes already being observed. The new results highlight the need for further development of a better understanding of ice-sheet dynamics in a changing climate.
Sarah Watts | alfa
Innovative genetic tests for children with developmental disorders and epilepsy
11.07.2018 | Christian-Albrechts-Universität zu Kiel
Oxygen loss in the coastal Baltic Sea is “unprecedentedly severe”
05.07.2018 | European Geosciences Union
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering | <urn:uuid:eb102e04-7b54-491c-96ce-5d41d91907e4> | 3.828125 | 1,186 | Content Listing | Science & Tech. | 41.320704 | 95,534,614 |
A recent slowdown in the upward march of global temperatures is likely to be the result of the slow warming of the deep oceans, British scientists said on Monday.
Oceans are some of the Earth’s biggest absorbers of heat, which can be seen in effects such as sea level rises, caused by the expansion of large bodies of water as they warm. The absorption goes on over long periods, as heat from the surface is gradually circulated to the lower reaches of the seas.
Temperatures around the world have been broadly static over the past five years, though they were still significantly above historic norms, and the years from 2000 to 2012 comprise most of the 14 hottest years ever recorded. The scientists said the evidence still clearly pointed to a continuation of global warming in the coming decades as greenhouse gases in the atmosphere contribute to climate change.
This summer’s heatwave, the most prolonged period of hot weather in the UK for years, has not yet been taken into account in their measurements.
Peter Stott of the Met Office said computer-generated climate models all showed that periods of slower warming were to be expected as part of the natural variation of the climate cycle, and did not contradict predictions. Given that variation, current temperatures are within expectations.
As well as the heating of the deep oceans, other factors have played a significant part in slowing temperature rises. These have included the solar minimum – when the sun is less active and generating slightly less heat, as occurred in 2008/2009 – and a series of small volcanic eruptions, including that of Iceland’s Eyjafjallajökull volcano in 2010. Ash from volcanoes reflects light back into space, and major eruptions in the past have had a severe, albeit temporary, cooling effect.
Despite the slowdown in warming, by 2060 the world is still likely to have experienced average temperatures of more than 2C above pre-industrial levels – a threshold that scientists regard as the limit of safety, beyond which climate change impacts are likely to become catastrophic. Prof Rowan Sutton, director of climate research at the National Centre for Atmospheric Research at Reading University, said the current pause would only delay reaching this point by five to 10 years.
The “pause” in the rise of global temperatures has been seized on by climate sceptics, however, who have interpreted it as proof that the science of climate change is mistaken. Despite the slowdown in warming, the warmest years on record were 1998, 2005 and 2010, according to the US National Oceanic and Atmospheric Administration.
Prof Sutton added that more research was needed on the effects of warming on the deep oceans, as observations of deep ocean temperatures have only been carried out in detail over the past decade and more are needed. Higher temperatures could not only have a devastating effect on marine life, he said, but could also cause increases in sea levels because sea water expands when heated.
The Met Office warned early in the summer that the UK could be in for a decade of “washout” summers, like those of the past six years, because of the effect of climate change on global weather systems, partly as a result of changes in wind patterns caused by the melting Arctic.
But no sooner had the meteorologists made their prediction than the weather bucked this trend with a shift in the Atlantic’s jet stream air circulation system giving rise to high-pressure weather fronts and a long period of settled sunny weather. | <urn:uuid:fb394776-d472-40b4-885a-9ab02de765ef> | 3.84375 | 701 | Truncated | Science & Tech. | 32.590142 | 95,534,616 |
The prominences are sometimes also the inner structure of a larger formation, appearing from the side almost as the filament inside a large light bulb. The bright structure around and above that light bulb is called a streamer, and the inside "empty" area is called a coronal prominence cavity.
Scientists want to understand what causes giant explosions in the sun's atmosphere, the corona, such as this one. The eruptions are called coronal mass ejections or CMEs and they can travel toward Earth to disrupt human technologies in space. To better understand the forces at work, a team of researchers used NASA data to study a precursor of CMEs called coronal cavities. Credit: NASA/Solar Dynamics Observatory (SDO)
The faint oval hovering above the upper left limb of the sun in this picture is known as a coronal cavity. NASA’s Solar and Terrestrial Relations Observatory (STEREO) captured this image on Aug. 9, 2007. A team of scientists extensively studied this particular cavity in order to understand more about the structure and magnetic fields in the sun's atmosphere. Credit: NASA/STEREO
Such structures are but one of many that the roiling magnetic fields and million-degree plasma create in the sun's atmosphere, the corona, but they are an important one as they can be the starting point of what's called a coronal mass ejection, or CME. CMEs are billion-ton clouds of material from the sun’s atmosphere that erupt out into the solar system and can interfere with satellites and radio communications near Earth when they head our way.
"We don't really know what gets these CMEs going," says Terry Kucera, a solar scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "So we want to understand their structure before they even erupt, because then we might have a better clue about why it's erupting and perhaps even get some advance warning on when they will erupt."
Kucera and her colleagues have published a paper in the Sept. 20, 2012, issue of The Astrophysical Journal on the temperatures of the coronal cavities. This is the third in a series of papers -- the first discussed cavity geometry and the second its density -- collating and analyzing as much data as possible from a cavity that appeared over the upper left horizon of the sun on Aug. 9, 2007 (below). By understanding these three aspects of the cavities, that is the shape, density and temperature, scientists can better understand the space weather that can disrupt technologies near Earth.
The Aug. 9 cavity lay at a fortuitous angle that maximized observations of the cavity itself, as opposed to the prominence at its base or the surrounding plasma. Together the papers describe a cavity in the shape of a croissant, with a giant inner tube of looping magnetic fields -- think something like a slinky -- helping to define its shape. The cavity appears to be 30% less dense than the streamer surrounding it, and the temperatures vary greatly throughout the cavity, but on average range from 1.4 million to 1.7 million Celsius (2.5 to 3 million Fahrenheit), increasing with height.
Trying to describe a cavity, a space that appears empty from our viewpoint, from 93 million miles away is naturally a tricky business. "Our first objective was to completely pin down the morphology," says Sarah Gibson, a solar scientist at the High Altitude Observatory at the National Center for Atmospheric Research (NCAR) in Boulder, Colo. who was an author on all three cavity papers. "When you see such a crisp clean shape like this, it’s not an accident. That shape is telling you something about the physics of the magnetic fields creating it, and understanding those magnetic fields can also help us understand what’s at the heart of CMEs."
To do this, the team collected as much data from as many instruments from as many perspectives as they could, including observations from NASA’s Solar Terrestrial Relations Observatory (STEREO), ESA and NASA’s Solar and Heliospheric Observatory (SOHO), the JAXA/NASA mission Hinode, and NCAR's Mauna Loa Solar Observatory.
They collected this information for the cavity’s entire trip across the face of the sun along with the sun’s rotation. Figuring out, for example, why the cavity was visible on the left side of the sun but couldn’t be seen as well on the right held important clues about the structure’s orientation, suggesting a tunnel shape that could be viewed head on from one perspective, but was misaligned for proper viewing from the other. The cavity itself looked like a tunnel in a crescent shape, not unlike a hollow croissant. Magnetic fields loop through the croissant in giant circles to support the shape, the way a slinky might look if it were narrower on the ends and tall in the middle – the entire thing draped in a sheath of thick plasma. The paper describing this three-dimensional morphology appeared in The Astrophysical Journal on Dec. 1, 2010.
Next up, for the second paper, was the cavity’s density. Figuring out density and temperature was a trickier prospect since one’s point of view of the sun is inherently limited. Because the sun’s corona is partially transparent, it is difficult to tease out differences of density and temperature along one’s line of sight; all the radiation from a given line hits an instrument at the same time in a jumble, information from one area superimposed upon every other.
Using a variety of techniques to tease density out from temperature, the team was able to determine that the cavity was 30% less than that of the surrounding streamer. This means that there is, in fact, quite a bit of material in the cavity. It simply appears dim to our eyes when compared with the denser, brighter areas nearby. The paper on the cavity’s density appeared in The Astrophysical Journal on May 20, 2011.
"With the morphology and the density determined, we had found two of the main characteristics of the cavity, so next we focused on temperature," says Kucera. "And it turned out to be a much more complicated problem. We wanted to know if it was hotter or cooler than the surrounding material – the answer is that it is both."
Ultimately, what Kucera and her colleagues found was that the temperature of the cavity was not – on average – hotter or cooler than the surrounding plasma.
However, it was much more varied, with hotter and cooler areas that Kucera thinks link the much colder 10,000 degrees Celsius (17,000 F) prominence at the bottom to the million to two million degrees Celsius (1.8 million to 3.6 million degrees Fahrenheit) corona at the top. Other observations of cavities show that cavity features are constantly in motion creating a complicated flow pattern that the team would like to study further.
While these three science papers focused on just the one cavity from 2007, the scientists have already begun comparing this test case to other cavities and find that the characteristics are fairly consistent. More recent cavities can also be studied using the high-resolution images from NASA’s Solar Dynamics Observatory (SDO), which launched in 2010.
"Our point with all of these research projects into what might seem like side streets, is ultimately to figure out the physics of magnetic fields in the corona," says Gibson. "Sometimes these cavities can be stable for days and weeks, but then suddenly erupt into a CME. We want to understand how that happens. We’re accessing so much data, so it’s an exciting time – with all these observations, our understanding is coming together to form a consistent story."Karen C. Fox
Susan Hendrix | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
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18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine | <urn:uuid:97d8da27-a864-44be-bb2b-a2ae92cc15fc> | 3.765625 | 2,262 | Content Listing | Science & Tech. | 45.548911 | 95,534,627 |
Origin and evolution of a submarine large igneous province: the Kerguelen Plateau and Broken Ridge, southern Indian Ocean
Oceanic plateaus form by mantle processes distinct from those forming oceanic crust at divergent plate boundaries. Eleven drillsites into igneous basement of Kerguelen Plateau and Broken Ridge, including seven from the recent Ocean Drilling Program Leg 183 (1998–99) and four from Legs 119 and 120 (1987–88), show that the dominant rocks are basalts with geochemical characteristics distinct from those of mid-ocean ridge basalts. Moreover, the physical characteristics of the lava flows and the presence of wood fragments, charcoal, pollen, spores and seeds in the shallow water sediments overlying the igneous basement show that the growth rate of the plateau was sufficient to form subaerial landmasses. Most of the southern Kerguelen Plateau formed at ∼110 Ma, but the uppermost submarine lavas in the northern Kerguelen Plateau erupted during Cenozoic time. These results are consistent with derivation of the plateau by partial melting of the Kerguelen plume. Leg 183 provided two new major observations about the final growth stages of the Kerguelen Plateau. 1: At several locations, volcanism ended with explosive eruptions of volatile-rich, felsic magmas; although the total volume of felsic volcanic rocks is poorly constrained, the explosive nature of the eruptions may have resulted in globally significant effects on climate and atmospheric chemistry during the late-stage, subaerial growth of the Kerguelen Plateau. 2: At one drillsite, clasts of garnet–biotite gneiss, a continental rock, occur in a fluvial conglomerate intercalated within basaltic flows. Previously, geochemical and geophysical evidence has been used to infer continental lithospheric components within this large igneous province. A continental geochemical signature in an oceanic setting may represent deeply recycled crust incorporated into the Kerguelen plume or continental fragments dispersed during initial formation of the Indian Ocean during breakup of Gondwana. The clasts of garnet–biotite gneiss are the first unequivocal evidence of continental crust in this oceanic plateau. We propose that during initial breakup between India and Antarctica, the spreading center jumped northwards transferring slivers of the continental Indian plate to oceanic portions of the Antarctic plate.
Frey, F.A., Coffin, M.F., Wallace, P.J., Weis, D., Zhao, X., Wise Jr., S.R., ...Antretter, M. (2000). Origin and evolution of a submarine large igneous province: the Kerguelen Plateau and Broken Ridge, southern Indian Ocean. Earth and Planetary Science Letters,176(1), 73-89. https://doi.org/10.1016/S0012-821X(99)00315-5
Virtual Commons Citation
Frey, F. A.; Coffin, M. F.; Wallace, P. J.; Weis, D.; Zhao, X.; Wise, S. R. Jr.; Wähnert, V.; Teagle, D. A.H.; Saccocia, Peter; Reusch, D. N.; Pringle, M. S.; Nicolaysen, K. E.; Neal, C. R.; Müller, R. D.; Moore, C. L.; Mahoney, J. J.; Keszthelyi, L.; Inokuchi, H.; Duncan, R. A.; Delius, H.; Damuth, J. E.; Damasceno, D.; Coxall, H. K.; Borre, M. K.; Boehm, F.; Barling, J.; Arndt, N. T.; and Antretter, M. (2000). Origin and evolution of a submarine large igneous province: the Kerguelen Plateau and Broken Ridge, southern Indian Ocean. In Geological Sciences Faculty Publications. Paper 6.
Available at: http://vc.bridgew.edu/geology_fac/6 | <urn:uuid:9cc4ad85-b9c0-479e-8b14-1aaa66d6d89a> | 3.40625 | 856 | Academic Writing | Science & Tech. | 56.489593 | 95,534,656 |
In this problem we required interior temperatures of a circuit combining brick and plaster, also calculate the thickness of plaster for reducing the heat loss.© BrainMass Inc. brainmass.com July 20, 2018, 12:49 pm ad1c9bdddf
I have solved this problem by calculating different thermal resistances and heat loss then by using it we can calculate interior temperature.
As given in problem
There is no radiation heat transfer so there will be no effect of e.
Interior heat transfer is given as
hi = 40 W/m2 K
ho = 30 W/m2 K
So overall heat transfer coefficient
1/h = 1/ hi + 1/ho
= 1/40 +1/30
h = 120/7
h = 17.14 W/m2 K
Now we will calculate thermal resistances
Then thermal resistance at surrounding will ...
The thermal circuit of brick and plaster heat transports are examined. The circuit combining brick and plasters are provided. | <urn:uuid:aee46917-9e97-4737-ba0a-7cd1ef7dbc42> | 3.453125 | 207 | Q&A Forum | Science & Tech. | 73.564787 | 95,534,658 |
Iron represents perhaps the best-known example for allotropy in a metal. At atmospheric pressure, three allotropic forms of iron exist: alpha iron (α), gamma iron (γ) also known as austenite, and delta iron (δ). At very high pressure, a fourth form exists, called epsilon iron (ε) hexaferrum. Some controversial experimental evidence exists for another high-pressure form that is stable at very high pressures and temperatures.
The phases of iron at atmospheric pressure are important because of the differences in solubility of carbon, forming different types of steel. The high-pressure phases of iron are important as models for the solid parts of planetary cores. The inner core of the Earth is generally assumed to consist essentially of a crystalline iron-nickel alloy with ε structure. The outer core surrounding the solid inner core is believed to be composed of liquid iron mixed with nickel and trace amounts of lighter elements.
As molten iron cools down, it solidifies at 1,538 °C (2,800 °F) into its δ allotrope, which has a body-centered cubic (BCC) crystal structure. δ-iron can dissolve as much as 0.09% of carbon by mass at 1,493 °C.
As the iron cools further to 1,394 °C its crystal structure changes to a face centered cubic (FCC) crystalline structure. In this form it is called gamma iron (γ-Fe) or Austenite. γ-iron can dissolve considerably more carbon (as much as 2.04% by mass at 1,146 °C). This γ form of carbon saturation is exhibited in stainless steel.
Beta iron (β-Fe) are obsolete terms for the paramagnetic allotrope of iron. The primary phase of low-carbon or mild steel and most cast irons at room temperature is ferromagnetic α-Fe. As iron or steel is heated above the critical temperature A2 or Curie temperature of 771 °C (1044K or 1420 °F), the random thermal agitation of the atoms exceeds the oriented magnetic moment of the unpaired electron spins. The A2 forms the low-temperature boundary of the beta iron field in the phase diagram in Figure 1. β-Fe is crystallographically identical to α-Fe, except for magnetic domains and the expanded body-centered cubic lattice parameter as a function of temperature, and is therefore of only minor importance in steel heat treating. For this reason, the beta "phase" is not usually considered a distinct phase but merely the high-temperature end of the alpha phase field.
Similarly, the A2 is of only minor importance compared to the A1 (eutectoid), A3 and Acm critical temperatures. The Acm, where austenite is in equilibrium with cementite + γ-Fe, is beyond the right edge in Fig. 1. The α + γ phase field is, technically, the β + γ field above the A2. The beta designation maintains continuity of the Greek-letter progression of phases in iron and steel: α-Fe, β-Fe, austenite (γ-Fe), high-temperature δ-Fe, and high-pressure hexaferrum (ε-Fe).
β-Fe and the A2 critical temperature are important in induction heating of steel, such as for surface-hardening heat treatments. Steel is typically austenitized at 900–1000 °C before it is quenched and tempered. The high-frequency alternating magnetic field of induction heating heats the steel by two mechanisms below the Curie temperature: resistance or Joule (I2R) heating and ferromagnetic hysteresis losses. Above the A2, the hysteresis mechanism disappears and the required amount of energy per degree of temperature increase is substantially larger than below A2. Load-matching circuits may be needed to vary the impedance in the induction power source to compensate for the change.
Below 912 °C (1,674 °F) iron again adopts the BCC structure characteristic of α-iron, also called ferrite. The substance assumes a paramagnetic property. Carbon dissolves poorly in α-iron: no more than 0.021% by mass at 723 °C.
As it cools to 770 °C (1,418 °F), the Curie point (TC), the iron is a fairly soft metal and becomes ferromagnetic. As iron passes below the Curie temperature, no structural change occurs, but the magnetic properties as the magnetic domains become aligned. This form of iron is stable form at room temperature. α-Fe can be subjected to pressures up to ca. 15 GPa before transforming into a high-pressure form termed ε-iron, which crystallizes in a hexagonal close-packed (hcp) structure.
α-Fe is a component of steel and cast iron, conferring Ferromagnetism. It has a hardness of approximately 80 Brinell. the maximum solubility is about 0.02 wt% at 727 °C (1,341 °F) and 0.001% carbon at 0 °C (32 °F). When it dissolves in iron, carbon atoms occupy interstitial "holes". Being about twice the diameter of the tetrahedral hole, the carbon introduces a strong local strain field.
Mild steel (carbon steel with up to about 0.2 wt% C) consist mostly of α-Fe and increasing amounts of cementite (Fe3C, an iron carbide). The mixture adopts a laminar structure called pearlite. Since bainite and pearlite each contain α-Fe as a component, any iron-carbon alloy will contain some amount of α-Fe if it is allowed to reach equilibrium at room temperature. The amount of α-Fe depends on the cooling process.
At pressures above approximately 10 GPa and temperatures of a few hundred kelvin or less, α-iron changes into a hexagonal close-packed (hcp) structure, which is also known as ε-iron or hexaferrum; the higher-temperature γ-phase also changes into ε-iron, but does so at a higher pressure. Antiferromagnetism in alloys of epsilon-Fe with Mn, Os and Ru has been observed.
An alternate stable form, if it exists, may appear at pressures of at least 50 GPa and temperatures of at least 1,500 K; it has been thought to have an orthorhombic or a double hcp structure. as of December 2011, recent and ongoing experiments are being conducted on high-pressure and Superdense carbon allotropes. | <urn:uuid:d5adb34f-619d-440f-ba6e-76303c9a281e> | 3.921875 | 1,394 | Knowledge Article | Science & Tech. | 48.671999 | 95,534,660 |
Ecological light pollution
The effect that artificial light has upon organisms is highly variable, and ranges from beneficial (e.g. increased ability for predator species to observe prey) to immediately fatal (e.g. moths that are attracted to incandescent lanterns and are killed by the heat). It is also possible for light at night to be both beneficial and damaging for a species. As an example, humans benefit from using indoor artificial light to extend the time available for work and play, but the light disrupts the human circadian rhythm, and the resulting stress is damaging to health.
Through the various effects that light pollution has on individual species, the ecology of regions is affected. In the case where two species occupy an identical niche, the population frequency of each species may be changed by the introduction of artificial light if they are not equally affected by light at night. For example, some species of spiders avoid lit areas, while other species are happy to build their spider web directly on a lamp post. Since lamp posts attract many flying insects, the spiders that don't mind light gain an advantage over the spiders that avoid it, and consequently become more common. Changes in these species frequencies can then have knock-on effects, as the interactions between these species and others in the ecosystem are affected and food webs are altered. These ripple effects can eventually affect even diurnal plants and animals. As an example, changes in the activity of night active insects can change the survival rates of night blooming plants, which may provide food or shelter for diurnal animals.
The introduction of artificial light at night is one of the most drastic anthropogenic changes to the Earth, comparable to toxic pollution, land use change, and climate change due to increases in the concentration of green house gases.
- 1 Natural light cycles
- 2 Effects of light pollution on individual organisms
- 3 Effects of different wavelengths
- 4 Polarized light pollution
- 5 See also
- 6 References
- 7 External links
Natural light cycles
Diurnal (solar) cycle
The most obvious change in introducing light at night is the end of darkness in general. The day/night cycle is probably the most powerful environmental behavioral signal, as almost all animals can be categorized as nocturnal or diurnal. If a nocturnal animal is only active in extreme dark, it will be unable to live in lit areas. The most acute affects are directly next to streetlights and lit buildings, but the diffuse light of skyglow can extend out to hundreds of kilometers away from city centers.
Seasonal (solar) cycles
The axial tilt of the Earth results in seasons outside of the tropics. The change in the length of the day is the key signal for seasonal behavior (e.g. mating season) in non-tropical animals. The presence of light at night can result in "seasons out of time" , changing the behavior and thermoregulation of affected organisms. This effect can be deadly for small mammals in the winter, since when their body acts as if it's summer they don't maintain an adequate winter body temperature to survive winter nights.
The behavior of some animals (e.g. coyotes, bats, toads, insects) is keyed to the lunar cycle. Near city centers the level of skyglow often exceeds that of the full moon, so the presence of light at night can alter these behaviors, potentially reducing fitness.
In pristine areas, clouds blot out the stars and darken the night sky, resulting in the darkest possible nights. In urban and suburban areas, in contrast, clouds enhance the effect of skyglow, particularly for longer wavelengths. This means that the typical level of light is much higher near cities, but it also means that truly dark nights never occur in these areas.
Effects of light pollution on individual organisms
The attraction of insects to artificial light is one of the most well known examples of the effect of light at night on organisms. When insects are attracted to lamps they can be killed by exhaustion or contact with the lamp itself, and they are also vulnerable to predators like bats.
Insects are affected differently by the varying wavelengths of light, and many species can see ultraviolet and infrared light that is invisible to humans. Because of variances in perception, moths are more attracted to broad spectrum white and bluish light sources than they are to the yellow light emitted by low pressure sodium-vapor lamps.
Dragonflies perceive horizontally polarized light as a sign of water. For this reason, sources of water are indistinguishable from asphalt roads with polarized light pollution to them. Dragonflies searching for water either to drink or in which to lay eggs often land on roads or other dark flat reflective surfaces such as cars and remain there until they die of dehydration and hyperthermia.
Light pollution may hamper the mating rituals of fireflies, once they depend on their own light for courtship, resulting in decreased populations. In 2015 it was showed and quantified for the first time the negative effects of direct illumination after monitoring fireflies populations over four years. Fireflies are charismatic (which is a rare quality amongst insects) and are easily spotted by nonexperts, providing thus good flagship species to attract public attention; good investigation models for the effects of light on nocturnal wildlife; and finally, due to their sensibility and rapid response to environmental changes, good bioindicators for artificial night lighting.
Lights on tall structures can disorient migrating birds. Estimates by the U.S. Fish and Wildlife Service of the number of birds killed after being attracted to tall towers range from 4 to 5 million per year to an order of magnitude higher. The Fatal Light Awareness Program (FLAP) works with building owners in Toronto, Canada and other cities to reduce mortality of birds by turning out lights during migration periods.
Similar disorientation has also been noted for bird species migrating close to offshore production and drilling facilities. Studies carried out by Nederlandse Aardolie Maatschappij b.v. (NAM) and Shell have led to development and trial of new lighting technologies in the North Sea. In early 2007, the lights were installed on the Shell production platform L15. The experiment proved a great success since the number of birds circling the platform declined by 50–90%. Juvenile seabirds may also be disoriented by lights as they leave their nests and fly out to sea.
Ceilometers (searchlights) can be particularly deadly traps for birds , as they become caught in the beam and risk exhaustion and collisions with other birds. In the worst recorded ceilometer kill-off, on October 7–8, 1954, 50,000 birds from 53 different species were killed at Warner Robins Air Force Base.
At the turn of the century it was discovered that human eyes contain a non-imaging photosensor that is the primary regulator of the human circadian rhythm. This photosensor is particularly affected by blue light, and when it observes light the pineal gland stops the secretion of melatonin. The presence of light at night in human dwellings (or for shift workers) makes going to sleep more difficult and reduces the overall level of melatonin in the bloodstream, and exposure to a low-level incandescent bulb for 39 minutes is sufficient to suppress melatonin levels to 50%. Because melatonin is a powerful anti-oxidant, it is hypothesized that this reduction can result in an increased risk of breast and prostate cancer.
Other human health effects may include increased headache incidence, worker fatigue, medically defined stress, decrease in sexual function and increase in anxiety. Likewise, animal models have been studied demonstrating unavoidable light to produce adverse effect on mood and anxiety.
Zooplankton (e.g. Daphnia) exhibit diel vertical migration. That is, they actively change their vertical position inside of lakes throughout the day. In lakes with fish, the primary driver for their migration is light level, because small fish visually prey on them. The introduction of light through skyglow reduces the height to which they can ascend during the night. Because zooplankton feed on the phytoplankton that form algae, the decrease in their predation upon phytoplankton may increase the chance of algal blooms, which can kill off the lakes' plants and lower water quality.
Effects of different wavelengths
The effect that artificial light has upon organisms is wavelength dependent. While human beings cannot see ultraviolet light, it is often used by entomologists to attract insects. Generally speaking, blue light is more likely to be damaging to mammals because the non-imaging photoreceptors in mammalian eyes are most sensitive in the blue region. This means that if traditional vapor discharge streetlamps are replaced by white LEDs (which generally emit more of their radiation in the blue part of the spectrum), the ecological impact could be greater even if the total amount of radiated light is decreased.
Polarized light pollution
Artificial planar surfaces, such as glass windows or asphalt reflect highly polarized light. Many insects are attracted to polarized surfaces, because polarization is usually an indicator for water. This effect is called polarized light pollution, and although it is certainly a form of ecological photopollution, "ecological light pollution" usually refers to the impact of artificial light on organisms.
In the night, the polarization of the moonlit sky is very strongly reduced in the presence of urban light pollution, because scattered urban light is not strongly polarized. Since polarized moonlight is believed to be used by many animals for navigation, this screening is another negative effect of light pollution on ecology.
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- Owens, Avalon Celeste Stevahn; Meyer-Rochow, Victor Benno; Yang, En-Cheng (2018-02-07). "Short- and mid-wavelength artificial light influences the flash signals of Aquatica ficta fireflies (Coleoptera: Lampyridae)". PLOS ONE. 13 (2): e0191576. doi:10.1371/journal.pone.0191576. ISSN 1932-6203.
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- Johnston, D; Haines (1957). "Analysis of Mass Bird Mortality in October, 1954". The Auk.
- Provencio, Ignacio; Rodriguez, Ignacio R.; Jiang, Guisen; Hayes, William Pär; Moreira, Ernesto F.; Rollag, Mark D. (2000). "A Novel Human Opsin in the Inner Retina". The Journal of Neuroscience.
- Schulmeister, K.; Weber, M.; Bogner, W.; Schernhammer, E. (2002). "Application of melatonin action spectra on practical lighting issues". Final Report. The Fifth International LRO Lighting Research Symposium, Light and Human Health.
- Scott Davis; Dana K. Mirick; Richard G. Stevens (2001). "Night Shift Work, Light at Night, and Risk of Breast Cancer". Journal of the National Cancer Institute. 93 (20): 1557–1562. doi:10.1093/jnci/93.20.1557. PMID 11604479.
- Eva S. Schernhammer; Francine Laden; Frank E. Speizer; Walter C. Willett; David J. Hunter; Ichiro Kawachi; Graham A. Colditz (2001). "Rotating Night Shifts and Risk of Breast Cancer in Women Participating in the Nurses' Health Study". Journal of the National Cancer Institute. 93 (20): 1563–1568. doi:10.1093/jnci/93.20.1563. PMID 11604480.
- Susan L. Burks, Managing your Migraine, Humana Press, New Jersey (1994) ISBN 0-89603-277-9
- Cambridge Handbook of Psychology, Health and Medicine, edited by Andrew Baum, Robert West, John Weinman, Stanton Newman, Chris McManus, Cambridge University Press (1997) ISBN 0-521-43686-9
- L. Pijnenburg, M. Camps and G. Jongmans-Liedekerken, Looking closer at assimilation lighting, Venlo, GGD, Noord-Limburg (1991)
- Knez, I (2001). "EFFECTS OF COLOUR OF LIGHT ON NONVISUAL PSYCHOLOGICAL PROCESSES". Journal of Environmental Psychology. 21 (2): 201–208. doi:10.1006/jevp.2000.0198.
- Fonken, L K; Finy, M S; Walton, James C.; Weil, Zachary M.; Workman, Joanna L.; Ross, Jessica; Nelson, Randy J. (28 December 2009). "Influence of light at night on murine anxiety- and depressive-like responses". Behavioural Brain Research. 205 (2): 349–354. doi:10.1016/j.bbr.2009.07.001. PMID 19591880.
- M. Salmon (2003). "Artificial night lighting and sea turtles" (PDF). Biologist. 50: 163–168.[permanent dead link]
- Marianne V. Moore; Stephanie M. Pierce; Hannah M. Walsh; Siri K. Kvalvik; Julie D. Lim (2000). "Urban light pollution alters the diel vertical migration of Daphnia" (PDF). Verh. Internat. Verein. Limnol. 27: 1–4.
- Falchi, F; Cinzano P; Elvidge CD; Keith DM; Haim A (2011). "Limiting the impact of light pollution on human health, environment and stellar visibility". Journal of Environmental Management. in press (10): 2714–2722. doi:10.1016/j.jenvman.2011.06.029.
- International Dark-Sky Association (2010). "Visibility, Environmental, and Astronomical Issues Associated with Blue-Rich White Outdoor Lighting" (PDF). IDA White Paper.
- Horváth, Gábor; György Kriska; Péter Malik; Bruce Robertson (August 2009). "Polarized light pollution: a new kind of ecological photopollution". Frontiers in Ecology and the Environment. Accès Online. 7 (6): 317–325. doi:10.1890/080129.
- Kyba, C. C. M.; Ruhtz, T.; Fischer, J.; Hölker, F. (17 December 2011). "Lunar skylight polarization signal polluted by urban lighting". Journal of Geophysical Research. 116 (D24). Bibcode:2011JGRD..11624106K. doi:10.1029/2011JD016698.
- List of peer reviewed ecological light pollution research papers
- Fatal Light Awareness Program (FLAP) (Toronto)
- "Ecological Consequences of Artificial Night Lighting" (2002 conference, by the Urban Wildlands Group)
- International Dark-Sky Association
- Loss of the Night Network (LONNE) - European Research Network COST Aktion ES1204
- Verlust der Nacht - Loss of the Night – Interdisciplinary light pollution research project in Germany including ecology and chronobiology
- Light Pollution at Curlie (based on DMOZ) | <urn:uuid:10efcd63-2119-48b9-badd-676ec18af343> | 4.09375 | 4,198 | Knowledge Article | Science & Tech. | 59.723405 | 95,534,701 |
New research from DTU shows that eruptions on the Sun's surface not only send bursts of particles into Earth's atmosphere, but -- contrary to previous belief -- also remove electrons across large areas
Eruptions on the Sun's surface send clouds of electrically charged particles towards Earth, producing solar storms that--among other things--can trigger the beautiful Northern Lights over the Arctic regions.
But the storms may also have a strong impact on the efficiency of communication and navigation systems at high latitudes. It is therefore important to study the phenomena.
New research from DTU Space and University of New Brunswick (Prof. Richard Langley), NASA Jet Propulsion Laboratory (Dr. Attila Komjathy) and University of Illinois (Dr. Mark D. Butala) shows that, apparently, there is a surprising and unknown mechanism in play during solar storms. During solar storms, large bursts of electrons are usually sent into the part of Earth's atmosphere called the ionosphere, which starts about 80 kilometres above the Earth.
This phenomenon occurs especially at high latitudes. It happens because the magnetic field created by the eruption on the Sun interferes with the Earth's magnetic field. It opens, so to speak, up to allow particles and electrons--that would otherwise be reflected--to penetrate the ionosphere.
It is a known phenomenon. But it turns out that electrons at the same time disappear from large areas, which has not been demonstrated earlier.
"We made extensive measurements in connection with a specific solar storm over the Arctic in 2014, and here we found that electrons in large quantities are virtually vacuum-cleaned from areas extending over 500 to 1,000 kilometres. It takes place just south of an area with heavy increases in electron density, known as patches," says Professor Per Høeg from DTU Space.
The results of the research were recently published on the front page of the renowned scientific journal Radio Science. The discovery is an important piece in the jigsaw puzzle of understanding solar storms and their impact on the Earth's ionosphere.
It's a surprising discovery that we hadn't anticipated. We can see that it happens, but we don't know why. However, other datasets from Canada indirectly support our new observations," says Per Høeg.
Dramatic changes in magnetic field
The explanation of the phenomenon should probably be found in the geomagnetic processes in the Earth's magnetic field in a direction away from the Sun. The composition of the magnetic field undergoes dramatic changes in the area between the solar wind and the Earth's magnetic field, triggering powerful burst of energy.
"The forerunner to the phenomenon is a violent eruption on the Sun's surface--also known as coronal mass ejections or CME, where bubbles of hot plasma and gas in the form of particles, electrons, and a magnetic field are hurled in the direction of the Earth," says Per Høeg.
As the geomagnetic solar storm took place in the ionosphere over the Arctic in February 2014, it was measured via satellites and land-based measuring stations. Among other things, via the GPS network GNET in Greenland--which DTU helps run--via DTU's geomagnetic measuring stations, the global navigation system GPS, and various American and Canadian satellites. Thus, large data volumes from the solar storm were recorded.
The research extends far beyond the discovery that electrons are pulled out during solar storms. Tibor Durgonics, PhD student at DTU Space and main author of the new article in Radio Science:
"There are two aspects of this research. It can both be used for a number of practical purposes, and then there is a theoretical part which is about achieving a better basic understanding of these phenomena.
"Our work can contribute to making navigation more reliable during ionospheric storms in the Arctic region. Our new research has enabled us to identify a number of critical factors that affect the quality of satellite-based navigation, and to assess the probability of when these factors may occur. At a more theoretical level, we have found out that during solar storms, electrons are removed in the ionosphere, which is the opposite of what you intuitively would expect."
When the magnetic field from solar eruptions hits the Earth's magnetic field in the ionosphere, their force fields are mixed. Consequently, unstable areas--so-called patches--are created in the Earth's ionosphere, extending over large areas near the North Pole. The area of patches at the polar cap may extend over 500 to 1,000 kilometres with electron speeds exceeding 1,000 metres per second. This gives rise to surging powerful Northern Lights and creates turbulent conditions.
Interferes with navigation and communication systems
Knowledge about solar storms are important, as communication with airborne signals via satellites and radio play an increasingly important in society. Solar storms may interfere with GPS satellites and their signals, make radio communication fail, and cause extensive power failures.
The risk of disruptions in the ionosphere is one of the reasons why no routine flights are made over the Arctic, although this would shorten air travel between Europe and America. The high-frequency signals used by commercial flights over Greenland will be subject to interference during solar storms. The ability to predict and take into account these kinds of conditions is therefore important for future commercial air traffic in the region. The same applies to marine traffic in the Arctic.
Professor Per Høeg hopes that the work conducted at DTU Space--in addition to ensuring more knowledge about the phenomenon--will contribute to the development of communication and navigation systems that can take into account conditions during solar storms to ensure safe flights and sailing in the polar cap areas.
DTU Space is currently participating in several research projects under ESA and the EU's Horizon 2020 programme which develop systems that can handle the conditions during space weather and solar storm conditions for aviation and marine traffic, among other things.
Per Høeg | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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Today, at the Large Hadron Collider Physics conference (LHCP2015), the ATLAS and CMS collaborations presented the most precise measurements yet of Higgs boson properties. By combining Run 1 data from both experiments, the new measurements paint a clear picture of how the Higgs boson is produced, decays, and interacts with other particles.
Most of the matter in the Universe is made not of stuff we understand, but of invisible “dark matter” particles. We have yet to observe these mysterious particles on Earth, presumably because they interact so weakly with normal matter. The high energy collisions in the Large Hadron Collider provide our best current hope of making dark matter particles, and thus giving us a better understanding what most of the Universe is made of.
One of the most basic quantities in particle physics, the rate at which protons scatter off of one another (the cross section), cannot be calculated from the theory of strong interactions, quantum chromodynamics. It must instead be measured, and those measurements can then be used to tune the numerical models of LHC proton–proton collisions.
W and Z bosons are the massive carriers of the weak force, responsible for radioactive decays. These bosons also couple closely to the Higgs boson. W and Z bosons are produced at a large rate in proton-proton collisions at the LHC, where ATLAS physicists have now measured the rates for W and Z boson production using 13 TeV proton-proton collisions
ATLAS Outreach Co-coordinator Kate Shaw has been awarded the 2015 European Physical Society (EPS) Outreach prize "for her contributions to the International Masterclasses and for her pioneering role in bringing them to countries with no strong tradition in particle physics".
A new set of techniques is being used to identify highly energetic top quarks, W and Z bosons, and Higgs bosons decaying to quarks and, ultimately, to hadrons measured in ATLAS. Signatures of these “boosted” Standard Model particles are particularly useful when searching for massive new particles and measuring processes at high energies.
After a shutdown of more than two years, Run 2 of the Large Hadron Collider (LHC) has restarted with proton–proton collisions at a centre-of-mass energy of 13 TeV. This new phase will allow the LHC experiments to explore nature and probe the physical laws governing it at scales never reached before.
With a precision of just under 14% − currently dominated by our ability to understand how many proton-proton collisions have occurred at ATLAS (i.e. luminosity) − this measurement is able to confirm that quantum chromodynamics, the theory of the strong interaction, still seems to be going strong!
Previous studies of two-particle angular correlations in proton-proton, proton-lead, and lead-lead collisions at the LHC have provided important insight on the physics of the particle production process. On 24 July, Atlas presented new preliminary measurements of two-particle correlations...
ATLAS is ready for detailed physics studies. The experiment used early data collected from the LHC’s Run 2 to calibrate its detectors. Measurements of the production and leptonic decay of certain particle resonances have shown that the detectors and software are working as expected. | <urn:uuid:a32abf3a-b5b8-458b-9817-0dde5edd0535> | 3.296875 | 688 | News (Org.) | Science & Tech. | 34.285589 | 95,534,741 |
Species Detail - Audouinella microscopica - 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).
(Nägeli ex Kützing) Woelkerling
5 May (recorded in 1985)
19 September (recorded in 1986)
National Biodiversity Data Centre, Ireland, Audouinella microscopica, accessed 20 July 2018, <https://maps.biodiversityireland.ie/Species/365> | <urn:uuid:3629bc13-965c-41d2-9f8f-7a429244303e> | 2.6875 | 145 | Structured Data | Science & Tech. | 33.246137 | 95,534,783 |
Global warming gases 'hit record high' says UN panel - but CO2 may not be worst
- Carbon dioxide levels at highest level since 1750
- Nitrous oxide '298 times' more potent than CO2
- Ozone-depleting CFC levels dropping - but substitutes now cause warming effect
- Effects of gases are 'complex' and 'unexpected'
Levels of CO2 have risen above the UN climate panel's predictions: But the board warns that other gases are also having an effect - and that we need to understand the earth's systems more fully
Global warming gases have increased beyond the worst predictions of the UN's climate experts - exceeding the worst of seven emissions predictions laid down by the UN's World Meteorological Organisations.
Weather stations in the Andes, in Alaska and the south Pacific helped to gather the data, which showed surges in various 'greenhouse' gases, including gases used as replacements for the CFCs previously blamed for eroding the ozone layer.
Nitrous oxide - released by fertilisers, as well as tropical soils and oceans - is also emerging as a potent greenhouse gas.
Carbon dioxide levels have also surged.
The WMO said that we need to further understand how so-called 'greenhouse gases' interact with Earth's natural cycles, the biosphere and oceans.
Global warming gases are at record levels from emissions, the UN's weather agency has warned.
The World Meteorological Organisation said heat-trapping carbon dioxide concentrations in the air have increased by 39 per cent to 389 parts per million - the highest concentrations since the start of the industrial era in 1750.
The rate of increase has accelerated, according to the World Meteorological Organization’s Greenhouse Gas Bulletin.
It focused special attention on rising nitrous oxide concentrations.
Between 1990 and 2010, according to the report, there was a 29% increase in the warming effect on our climate system - from greenhouse gases.
Carbon dioxide accounted for 80% of this increase.
“The atmospheric burden of greenhouse gases has yet again reached record levels since pre-industrial time,' said WMO Secretary-General Michel Jarraud.
NASA thermal satellite image showing the world's arctic surface temperature: The UN climate panel has based its readings of gas levels on weather stations in 50 countries including stations in the Andes and Alaska
'Now more than ever before, we need to understand the complex, and sometimes unexpected, interactions between greenhouse gases in the atmosphere, Earth’s biosphere and oceans.'
'WMO will continue to collect data to further our scientific knowledge through its Global Atmosphere Watch network spanning more than 50 countries, including stations high in the Andes and Himalayas, in the remote expanses of Alaska and in the far South Pacific,' he said.
However, concentrations of other gases such as HCFCs and HFCs, which are
used to substitute CFCs because they are less damaging to the ozone
layer, are increasing rapidly.
These two classes of compounds are very potent greenhouse gases and last much longer in the atmosphere than carbon dioxide.
Between 2009 and 2010, carbon dioxide's atmospheric abundance increased by 2.3 parts per million – higher than the average for both the 1990s (1.5 parts per million) and the past decade (2.0 parts per million).
One of the World Meteorological Organisation's climate maps: The organisation urged further research into the 'unpredictable' effect of gases on our atmosphere
Methane contributes about 18% to the overall global increase in warming since 1750 and is the second most important greenhouse gas after carbon dioxide - released into the atmosphere by activities such as cattle farming and landfill sites.
The scientists were also highly concerned about the increase in nitrous oxide in the atmossphere.
It has grown rapidly over the past ten years, mainly as a result of the use of nitrogen containing fertilizers, including manure, which has profoundly affected the global nitrogen cycle - but is also released by tropical soils and oceans.
Its impact on climate, over a 100 year period, is 298 times greater than equal emissions of carbon dioxide.
It also plays an important role in the destruction of the stratospheric ozone layer which protects us from the harmful ultraviolet rays of the sun.
The new Greenhouse Gas Bulletin is the seventh in the series, which began in 2004.
It said that reflects a 20% increase in nitrous oxide, 39% rise in CO2 and 158% jump in methane since then.
The concentrations exceed the worst of seven emissions scenarios in 2001 from the UN's expert climate panel.
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The expected numbers of different categories of polymorphic sites are derived for two related models of population history the isolation model, in which an ancestral population splits into two descendents, and the size-change model, in which a single population undergoes an instantaneous change in size. For the isolation model, the observed numbers of shared, fixed, and exclusive polymorphic sites are used to estimate the relative sizes of the three populations, ancestral plus two descendent, as well as the time of the split. For the size change model, the numbers of sites segregating at particular frequencies in the sample are used to estimate the relative sizes of the ancestral and descendent populations plus the time the change took place. Parameters are estimated by choosing values that most closely equate expectations with observations. Computer simulations show that current and historical population parameters can be estimated accurately. The methods are applied to DNA data from two species of Drosophila and to some human mitochondrial DNA sequences.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:45437c58-5879-472f-9d6e-14fb57b2d8e1> | 3.5 | 210 | Academic Writing | Science & Tech. | 4.835 | 95,534,799 |
As we near the final month of summer in the Northern Hemisphere, NASA scientists are watching the annual seasonal melting of the Arctic sea ice cover. The floating, frozen cap that stretches across the Arctic Ocean shrinks throughout summer until beginning to regrow, typically around mid-September.
As of Aug. 19, Arctic sea ice covered about 2.31 million square miles. While this is on track to be larger than the record-breaking low year in 2012, the sea ice extent is still well below average for the past 30 years, and continues a trend of sea ice loss in the Arctic. From 1981 to 2010, the average sea ice extent on Aug. 19 was 2.72 million square miles – 18 percent larger than on that same date this year.
"While this year is not heading toward a record low minimum extent in the Arctic, sea ice is well below normal and continues an overall pattern of decreasing sea ice during summer in the Arctic,” said sea ice scientist Walt Meier, based at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
While NASA scientists have used satellites to document sea ice changes for more than 40 years, this summer the agency is also flying three airborne research campaigns to observe different aspects of climate-driven change in the Arctic.
The ARISE (Arctic Radiation-IceBridge Sea and Ice Experiment) campaign will begin flights later this week from Greenland to measure how changing land and sea ice conditions in the region are affecting the formation of clouds and the exchange of heat from Earth’s surface to space.
For some time scientists at NASA and elsewhere have been concerned about how the retreat of sea ice in summer could affect the climate of the Arctic. This campaign is one of the first to study the interaction between sea ice loss and the Arctic atmosphere.
The CARVE (Carbon in Arctic Reservoirs Vulnerability Experiment) campaign is making its third year of flights from Fairbanks, Alaska, over vast regions of Alaska to measure the emissions of greenhouse gases being released from thawing tundra and permafrost.
And an offshoot of NASA’s long-running Operation IceBridge, a plane will fly over Alaskan glaciers to measure how much the thickness of those glaciers has changed from previous years.
For news on these campaigns and the status of Arctic sea ice as it progresses toward its annual minimum, watch for updates on www.nasa.gov/earth and www.nasa.gov/earthrightnow throughout August and September.
NASA’s Earth Science News Team
Patrick Lynch | Eurek Alert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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By: Barbara W Murck
360 pages, b/w illus
This Wiley Self-Teaching Guide introduces learners to all the basics of environmental science, from air pollution to the water cycle, covering both natural systems and human impacts on the environment. Using quick quizzes and self-tests to reinforce key concepts, Environmental Science walks students through this interdisciplinary topic with clarity and thoroughness. With 125 photographs and illustrations, this book is a unique and valuable resource for anyone interested in learning more about-and in preserving-our green home.
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Visualising DNA in Action
3D genome from individual mouse stem cell Credit: University of Cambridge/MRC Laboratory of Molecular Medicine
Scientists have determined the first 3D structures of intact mammalian genomes from individual cells, showing how the DNA from all the chromosomes intricately folds to fit together inside the cell nuclei.
Researchers from the University of Cambridge and the MRC Laboratory of Molecular Biology used a combination of imaging and up to 100,000 measurements of where different parts of the DNA are close to each other to examine the genome in a mouse embryonic stem cell. Stem cells are ‘master cells’, which can develop – or ‘differentiate’ – into almost any type of cell within the body.
Most people are familiar with the well-known ‘X’ shape of chromosomes, but in fact chromosomes only take on this shape when the cell divides. Using their new approach, the researchers have now been able to determine the structures of active chromosomes inside the cell, and how they interact with each other to form an intact genome. This is important because knowledge of the way DNA folds inside the cell allows scientists to study how specific genes, and the DNA regions that control them, interact with each other. The genome’s structure controls when and how strongly genes – particular regions of the DNA – are switched ‘on’ or ‘off’. This plays a critical role in the development of organisms and also, when it goes awry, in disease.
The researchers have illustrated the structure in accompanying videos, which show the intact genome from one particular mouse embryonic stem cell. In the film, above, each of the cell’s 20 chromosomes is coloured differently.
In a second video, below, regions of the chromosomes where genes are active are coloured blue, and the regions that interact with the nuclear lamina (a dense fibrillar network inside the nucleus) are coloured yellow. The structure shows that the genome is arranged such that the most active genetic regions are on the interior and separated in space from the less active regions that associate with the nuclear lamina. The consistent segregation of these regions, in the same way in every cell, suggests that these processes could drive chromosome and genome folding and thus regulate important cellular events such as DNA replication and cell division.
Professor Ernest Laue, whose group at Cambridge’s Department of Biochemistry developed the approach, commented: “Knowing where all the genes and control elements are at a given moment will help us understand the molecular mechanisms that control and maintain their expression.
“In the future, we’ll be able to study how this changes as stem cells differentiate and how decisions are made in individual developing stem cells. Until now, we’ve only been able to look at groups, or ‘populations’, of these cells and so have been unable to see individual differences, at least from the outside. Currently, these mechanisms are poorly understood and understanding them may be key to realising the potential of stem cells in medicine."
The research, by scientists at the Departments of Biochemistry, Chemistry and the Wellcome-MRC Stem Cell Institute at the University of Cambridge, together with colleagues at the MRC Laboratory of Molecular Biology, is published today in the journal Nature.
Dr Tom Collins from Wellcome’s Genetics and Molecular Sciences team said: “Visualising a genome in 3D at such an unprecedented level of detail is an exciting step forward in research and one that has been many years in the making. This detail will reveal some of the underlying principles that govern the organisation of our genomes – for example how chromosomes interact or how structure can influence whether genes are switched on or off. If we can apply this method to cells with abnormal genomes, such as cancer cells, we may be able to better understand what exactly goes wrong to cause disease, and how we could develop solutions to correct this.”
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Experts investigate the density of the wild boar population in Europe, and assess measures to reduce it and keep wild boar infected with African swine fever away from uninfected ones. They also identify ways to detect the disease early.READ MORE | <urn:uuid:43a80f23-242a-4465-b69c-21efa716d868> | 3.140625 | 863 | News Article | Science & Tech. | 23.611002 | 95,534,827 |
Can you change the direction of Forces in the diagram, or make two forces coverage at the same point, when looking at objects in equilibrium?
How would I do this question: a sign of mass 50kg is supported by a wire and a rod as shown in figure 13 ( Rod and wire meet at an angle of 30 degrees, with the sign suspended at the same point, perpendicular to the rod. The rod and wire meet a wall)
I understand the weight of the object will act downwards and tension will act in the wire; will there also be a support force in the rod; if do how would the diagram be drawn
Turn on thread page Beta
Triangle of Forces Physics help watch
- Thread Starter
- 22-01-2017 15:22
- Official Rep
- 24-01-2017 17:43
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Just quoting in Amusing Elk so she can move the thread if needed
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Craig Venter, known for his controversial leadership in deciphering the human genetic code, has constructed a synthetic chromosome which is the basic code needed in order to create life. Speculation is building that he is about announce the creation of the first artificial life form on earth. The hope is that custom life forms may one day be used to digest formerly indigestible things such as cellulose, and turn them into fuel in order solve the energy crisis, or to digest green house gas to ease global warming. | <urn:uuid:8c356a11-657b-42fb-8c5c-1f97bc23ed91> | 2.90625 | 212 | Truncated | Science & Tech. | 35.537046 | 95,534,871 |
If you know anything about the Large Hadron Collider, you know that it is huge. Massive. 17 miles of tunnels under Switzerland. Traditional accelerators need all that space to get particles to smash into each other at close to the speed of light. But scientists at Stanford have come one step closer to a new type of particle accelerator that could do the same at just a fraction of the size.
The key idea is plasma wakefield acceleration, and as the name implies, it's a bit like riding the wake behind a boat. Symmetry Magazine explains in detail:
Researchers sent pairs of electron bunches containing 5 billion to 6 billion electrons each into a laser-generated column of plasma inside an oven of hot lithium gas. The first bunch in each pair blasted all the free electrons away from the lithium atoms, leaving the positively charged lithium nuclei behind — a configuration known as the "blowout regime." The blasted electrons then fell back in behind the second bunch of electrons, forming a "plasma wake" that propelled the trailing bunch to higher energy.
The idea of particle wakefield acceleration has been bandied around for decades, but it's the first time scientists have achieved that "blowout regime" and boosted particles to such high energies. To put some numbers on it, this gives particles 400 to 500 times as much energy as a traditional accelerator would over the same distance.
The LHC is our most advanced particle accelerator yet, but eventually, we'll want more powerful accelerators to study particles bigger than the Higgs that could be the source of dark matter. The size and cost of these accelerators, however, would be formidable. And CERN, which runs the LHC, has already uses enough electricity to power 300,000 homes. The likely solution would be to think small, think plasma wakefields. [Symmetry, LiveScience, Nature]
Top image via SLAC | <urn:uuid:d80733e4-b4ef-4879-92de-b224110ef540> | 3.125 | 385 | Truncated | Science & Tech. | 42.102857 | 95,534,881 |
Proteins are solids. When heated they do not melt; instead, they decompose or sublime directly to the gas phase at low pressures. They cannot be converted into a liquid form unless they are dissolved in a solvent.
A team at the University of Bristol (UK) and the Max Planck Institute of Colloids and Interfaces in Golm (Germany) has now successfully liquefied a protein without the assistance of a solvent. As the research team headed by Stephen Mann reports in the journal Angewandte Chemie, the trick is to modify the surface of the protein with a polymeric surfactant.
The researchers used ferritin for their experiments. This large protein serves animals and plants as a storage material for iron. Ferritin forms a hollow sphere that can hold thousands of iron ions. Adam Perriman, a researcher in the Mann lab, attached polymer chains consisting of a polyethylene oxide portion and a hydrocarbon portion to these iron-containing ferritin spheres. About 240 polymer chains were attached to every ferritin molecule. A solution of proteins modified in this way was freeze-dried.
The resulting dry powder could be melted to form a transparent, viscous red liquid that solidified only upon cooling to –50 °C. In the temperature range between 30 and 37 °C the modified protein is in a liquid-crystalline state, which means the molecules are oriented more or less uniformly but (at least partly) lack the three-dimensional lattice that is formed in the crystalline state. At higher temperatures, the modified protein acts like a normal liquid. It only decomposes at temperatures above 400 °C.
How does the liquefaction work? The surfactant chains on the ferritin surface keep the protein spheres apart and shield their surfaces. This prevents the electrostatic attractive forces between polar molecular groups of neighboring spheres from holding the proteins together in a solid. The spheres are instead held together by attractive forces between the hydrocarbon ends of the surfactant chains. These forces are only strong enough to hold the molecules together as a liquid. Between 30 and 37 °C the surfactant chains arrange themselves in an ordered pattern, giving the substance liquid-crystalline properties.
“This is a very exciting result with fundamental significance for understanding liquids comprising nanostructured components,” says Mann. “Also, it represents a possible way forward to a novel state of biomolecular matter, and could therefore have a number of important applications, for example in biomedical and sensor technology.”
Author: Stephen Mann, University of Bristol (UK), http://www.chm.bris.ac.uk/inorg/mann/webpage.htm
Title: Solvent-Free Protein Liquids and Liquid Crystals
Angewandte Chemie International Edition 2009, 48, No. 34, 6242–6246, doi: 10.1002/anie.200903100
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
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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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Ever since Einstein proposed his special theory of relativity in 1905, physics and cosmology have been based on the assumption that space looks the same in all directions -- that it's not squeezed in one direction relative to another. A new experiment by physicists used partially entangled atoms -- identical to the qubits in a quantum computer -- to demonstrate more precisely than ever before that this is true: to one part in a billion billion.
The classic experiment that inspired Albert Einstein was performed in Cleveland by Albert Michelson and Edward Morley in 1887 and disproved the existence of an "ether" permeating space through which light was thought to move like a wave through water. What it also proved, said Hartmut Häffner, a UC Berkeley assistant professor of physics, is that space is isotropic and that light travels at the same speed up, down and sideways.
"Michelson and Morley proved that space is not squeezed," Häffner said. "This isotropy is fundamental to all physics, including the Standard Model of physics. If you take away isotropy, the whole Standard Model will collapse. That is why people are interested in testing this."
The Standard Model of particle physics describes how all fundamental particles interact, and requires that all particles and fields be invariant under Lorentz transformations, and in particular that they behave the same no matter what direction they move.
Häffner and his team conducted an experiment analogous to the Michelson-Morley experiment, but with electrons instead of photons of light. In a vacuum chamber he and his colleagues isolated two calcium ions, partially entangled them as in a quantum computer, and then monitored the electron energies in the ions as Earth rotated over 24 hours.
If space were squeezed in one or more directions, the energy of the electrons would change with a 12-hour period. It didn't, showing that space is in fact isotropic to one part in a billion billion (1018), 100 times better than previous experiments involving electrons, and five times better than experiments like Michelson and Morley's that used light.
The results disprove at least one theory that extends the Standard Model by assuming some anisotropy of space, he said.
Häffner and his colleagues, including former graduate student Thaned Pruttivarasin, now at the Quantum Metrology Laboratory in Saitama, Japan, will report their findings in the Jan. 29 issue of the journal Nature.
Häffner came up with the idea of using entangled ions to test the isotropy of space while building quantum computers, which involve using ionized atoms as quantum bits, or qubits, entangling their electron wave functions, and forcing them to evolve to do calculations not possible with today's digital computers. It occurred to him that two entangled qubits could serve as sensitive detectors of slight disturbances in space.
"I wanted to do the experiment because I thought it was elegant and that it would be a cool thing to apply our quantum computers to a completely different field of physics," he said. "But I didn't think we would be competitive with experiments being performed by people working in this field. That was completely out of the blue."
He hopes to make more sensitive quantum computer detectors using other ions, such as ytterbium, to gain another 10,000-fold increase in the precision measurement of Lorentz symmetry. He is also exploring with colleagues future experiments to detect the spatial distortions caused by the effects of dark matter particles, which are a complete mystery despite comprising 27 percent of the mass of the universe.
"For the first time we have used tools from quantum information to perform a test of fundamental symmetries, that is, we engineered a quantum state which is immune to the prevalent noise but sensitive to the Lorentz-violating effects," Häffner said. "We were surprised the experiment just worked, and now we have a fantastic new method at hand which can be used to make very precise measurements of perturbations of space."
The Daily Galaxy via University of California - Berkeley.
Image credit: Hartmut Haeffner, UC Berkeley | <urn:uuid:3d4f1a71-8562-40e0-89fe-9b8b2fcc2521> | 4.4375 | 845 | News Article | Science & Tech. | 31.280644 | 95,534,891 |
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- Open Access
How different are we from chimps?
© BioMed Central Ltd 2002
Published: 2 October 2002
It is often maintained that humans are more than 98.5% similar to chimpanzees in our DNA sequences. In the Early Edition of the Proceedings of the National Academy of Sciences, Roy Britten at Caltech challenges this dogma and shows that when sequence insertions and deletions (indels) are taken into account the divergence can be estimated at around 5% (PNAS, DOI:10.1073/pnas.172510699, September 23, 2002). Britten compared the sequence of five chimp BACs - covering 779 kilobases - with the draft human genome sequence. Sequence substitutions account for about 1.4% divergence, but twice as much divergence (3.6%) is contributed by indels. The frequency of indels is less than the frequency of substitutions, but the gaps can be tens of nucleotides long and appear in both human and chimp sequences. Further analysis of the gaps in other genomes may provide useful insights into evolutionary relationships between humans and our closest relatives. | <urn:uuid:d4479b1f-6d8b-4cb8-b4de-80a320ed2308> | 3.625 | 237 | Academic Writing | Science & Tech. | 48.897566 | 95,534,893 |
Disregarding point symmetry, we can simplify the crystal structure by the space group [1, 2], representing the thermodynamic state in equilibrium with the surroundings at given values of p and T. In this approach, the restoring forces secure stability of the lattice, where the masses at lattice points are in harmonic motion. In this case, we realize that their directional correlations in the lattice are ignored so that a possible disarrangement in the lattice can cause structural instability.
KeywordsPartition Function Normal Mode Lattice Vibration Conjugate Momentum Boltzmann Statistic
- 1.M. Tinkham, Group Theory and Quantum Mechanics (McGraw-Hill, New York, 1964)Google Scholar
- 2.R.S. Knox, A. Gold, Symmetry in the Solid State (Benjamin, New York, 1964)Google Scholar
- 3.C. Kittel, Quantum Theory of Solids, (John Wiley, New York, 1963)Google Scholar
- 4.C. Kittel, Introduction to Solid State Physics, 6th edn. (Wiley, New York, 1986)Google Scholar
- 5.C. Kittel, H. Kroemer, Thermal Physics (Freeman, San Francisco, 1980)Google Scholar | <urn:uuid:aec19858-2117-48d3-97ce-4344a9fcca62> | 2.578125 | 267 | Academic Writing | Science & Tech. | 54.37288 | 95,534,895 |
Created The Law of Conservation of Mass
Invented the Battery
Discovered Electromagnetic Induction
Invented Dynamite and the Nobel Peace prize was named after him
Invented the process of Pasteurization
Invented the Radio
Had her contribution to Radioavtivity.
Invented the T.V.
Invented the first Nuclear Chain Reaction
Invented the Polymerase Chain Reaction
Proposed the atomic theory with spherical solid atoms based upon measurable properties of mass and that atoms are indivisible
Created the term Cathode rays for the negatively charged electrons, and discovered anode rays, the positively charged particles
He discovered the electron by applying his own vacuum technique, and saying this matter being the substance from which all the chemical elements are built up
Using the worlds most sensitive electromagnetic wave detector at that time he discovered two distinct radiations, which he named them alpha and beta rays (high speed electrons)
He was the originator of the quantum theory, and explained the patteren of light intensity emmited from a black body at any given frequency. E=hv
Developed his theory of relativity and photoelectric effect
Discovered the charge of an atom in his 1909 oil drop experiments
Determined the importance of the atomic number over atomic mass, in his Moseley Law, which correlated wavelength and atomic number
Explained that electrons traveled in fixed orbits around the nucleus and also explained how electrons gain and lose energy. He created the quantum theory.
He discovered the wave nature of electrons, that the particles can behave like waves, and the waves can behave like particles. L=h/(m•v)
He introduced the Schrodinger wave, which was the mathematical equation of wave mechanics that is still the most widely used piece of mathematics in modern quantum theory. It posits a non-relativistic wave equation that governs how electrons behave within the hydrogen atom.
In his Uncertainty Principle it states that it is impossible to accurately measure both position and momentum at the same time, and that the more precisely we know an object's position the less precisely we can know its momentum, and vice versa.
He proved the existence of neutrons, and elemntary particle without any electrical charge and a building block of the nucleus | <urn:uuid:d6f4275e-59c2-4434-9f79-3ab89ec62641> | 3.4375 | 473 | Structured Data | Science & Tech. | 8.015293 | 95,534,901 |
Solar panel technology has plenty of room for improvement, especially in the efficiency category. While they're fantastic in terms of green energy, they can definitely be more efficient when it comes to how much light they absorb, and how long they hold onto that energy. We’ve seen them becoming more adaptive to the environment, such as thin-film solar cells, but that hasn't been without setback. Interestingly, butterfly wing-inspired design could provide the best way yet to generate solar power via panels.
Researchers from the California Institute of Technology and the Karlsruhe Institute of Technology have looking into how to improve thin solar cells. While efficiency has been sacrificed, they have benefits in all the other categories when compared to traditional solar cells. They have the ability to adapt onto any surface, they’re lighter, and often cheaper to produce.
Inspiration for a butterfly model came from the rose butterfly often found in India. Its black wings have the ability to warm itself in colder areas. Looking at the insect further, they discovered that the wings had little holes. This made the wings lighter for the insect and sunlight was able to be absorbed quicker since it was scattered through the holes.
Taking this further, CIT bioengineer Radwanul Siddique looked at computer models showcasing how this feature would work with solar panels. Holes on the butterfly differed in every aspect, such as how many there were, their size, and how they were shaped along the wings. The team determined that shape didn’t matter, but where they were located and how many there were was important.
“I think what’s interesting is the excellent approach of looking at the underlying physiological concepts and then taking these concepts and emulating them in a structure that doesn’t look quite look like how a butterfly looks but does the same physics,” Mathias Kolle told The Verge. Kolle, an engineering professor at the Massachusetts Institute of Technology, wasn’t a part of the research, but knew the benefits of the process.
They were able to easily convert the setup to multiple layers of hydrogenated amorphous silicon sheets. Amorphous silicon is the semiconductor frequently used in thin-film solar cells and they are environmentally friendly to produce when compared to the alternatives. Again, the shapes of the holes didn’t matter, but they put them in specific locations. The process only takes up to 10 minutes.
Test results were very positive, absorbing twice as much light when compared to other thin-film solar cells. According to Phys.org, rates saw an “increase of 90 percent at a normal incident angle of light to as high as 200 percent at large incident angles.” It’s a tremendous step for the solar technology as low efficiency, the biggest drawback, is being thwarted.
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A new report finds that meat and dairy producers are on track to surpass the oil industry's greenhouse gas emissions. | <urn:uuid:9171f45d-0e9d-438e-8a39-49b9b14cf975> | 3.9375 | 701 | News Article | Science & Tech. | 39.138643 | 95,534,931 |
A little background
As I mentioned, UML was meant to be a unifying language enabling IT professionals to model computer applications. The primary authors were Jim Rumbaugh, Ivar Jacobson, and Grady Booch, who originally had their own competing methods (OMT, OOSE, and Booch). Eventually, they joined forces and brought about an open standard. (Sound familiar? A similar phenomenon spawned J2EE, SOAP, and Linux.) One reason UML has become a standard modeling language is that it is programming-language independent. (UML modeling tools from IBM Rational are used extensively in J2EE shops as well in .NET shops.) Also, the UML notation set is a language and not a methodology. This is important, because a language, as opposed to a methodology, can easily fit into any company's way of conducting business without requiring change.
Since UML is not a methodology, it does not require any formal work products (i.e., "artifacts" in IBM Rational Unified Process® lingo). Yet it does provide several types of diagrams that, when used within a given methodology, increase the ease of understanding an application under development. There is more to UML than these diagrams, but for my purposes here, the diagrams offer a good introduction to the language and the principles behind its use. By placing standard UML diagrams in your methodology's work products, you make it easier for UML-proficient people to join your project and quickly become productive. The most useful, standard UML diagrams are: use case diagram, class diagram, sequence diagram, statechart diagram, activity diagram, component diagram, and deployment diagram.
It is beyond the scope of this introductory article to go into great detail about each type of diagram. Instead, I will provide you with enough information for a general understanding of each one and then supply more details in later articles.
A use case illustrates a unit of functionality provided by the system. The main purpose of the use-case diagram is to help development teams visualize the functional requirements of a system, including the relationship of "actors" (human beings who will interact with the system) to essential processes, as well as the relationships among different use cases. Use-case diagrams generally show groups of use cases — either all use cases for the complete system, or a breakout of a particular group of use cases with related functionality (e.g., all security administration-related use cases). To show a use case on a use-case diagram, you draw an oval in the middle of the diagram and put the name of the use case in the center of, or below, the oval. To draw an actor (indicating a system user) on a use-case diagram, you draw a stick person to the left or right of your diagram (and just in case you're wondering, some people draw prettier stick people than others). Use simple lines to depict relationships between actors and use cases, as shown in Figure 1.
A use-case diagram is typically used to communicate the high-level functions of the system and the system's scope. By looking at our use-case diagram in Figure 1, you can easily tell the functions that our example system provides. This system lets the band manager view a sales statistics report and the Billboard 200 report for the band's CDs. It also lets the record manager view a sales statistics report and the Billboard 200 report for a particular CD. The diagram also tells us that our system delivers Billboard reports from an external system called Billboard Reporting Service.
In addition, the absence of use cases in this diagram shows what the system doesn't do. For example, it does not provide a way for a band manager to listen to songs from the different albums on the Billboard 200 — i.e., we see no reference to a use case called Listen to Songs from Billboard 200. This absence is not a trivial matter. With clear and simple use-case descriptions provided on such a diagram, a project sponsor can easily see if needed functionality is present or not present in the system.
The class diagram shows how the different entities (people, things, and data) relate to each other; in other words, it shows the static structures of the system. A class diagram can be used to display logical classes, which are typically the kinds of things the business people in an organization talk about — rock bands, CDs, radio play; or loans, home mortgages, car loans, and interest rates. Class diagrams can also be used to show implementation classes, which are the things that programmers typically deal with. An implementation class diagram will probably show some of the same classes as the logical classes diagram.The implementation class diagram won't be drawn with the same attributes, however, because it will most likely have references to things like Vectors and HashMaps.
A class is depicted on the class diagram as a rectangle with three horizontal sections, as shown in Figure 2. The upper section shows the class's name; the middle section contains the class's attributes; and the lower section contains the class's operations (or "methods").
In my experience, almost every developer knows what this diagram is, yet I find that most programmers draw the relationship lines incorrectly. For a class diagram like the one in Figure 3, you should draw the inheritance relationship1 using a line with an arrowhead at the top pointing to the super class, and the arrowhead should be a completed triangle. [Note: For more information on inheritance and other object-oriented principles, see the Java tutorial What Is Inheritance?] An association relationship should be a solid line if both classes are aware of each other and a line with an open arrowhead if the association is known by only one of the classes.
In Figure 3, we see both the inheritance relationship and two association relationships. The CDSalesReport class inherits from the Report class. A CDSalesReport is associated with one CD, but the CD class doesn't know anything about the CDSalesReport class. The CD and the Band classes both know about each other, and both classes can be associated to one or more of each other.
A class diagram can incorporate many more concepts, which we will cover later in this article series.
Sequence diagrams show a detailed flow for a specific use case or even just part of a specific use case. They are almost self explanatory; they show the calls between the different objects in their sequence and can show, at a detailed level, different calls to different objects.
A sequence diagram has two dimensions: The vertical dimension shows the sequence of messages/calls in the time order that they occur; the horizontal dimension shows the object instances to which the messages are sent.
A sequence diagram is very simple to draw. Across the top of your diagram, identify the class instances (objects) by putting each class instance inside a box (see Figure 4). In the box, put the class instance name and class name separated by a space/colon/space " : " (e.g., myReportGenerator : ReportGenerator). If a class instance sends a message to another class instance, draw a line with an open arrowhead pointing to the receiving class instance; place the name of the message/method above the line. Optionally, for important messages, you can draw a dotted line with an arrowhead pointing back to the originating class instance; label the return value above the dotted line. Personally, I always like to include the return value lines because I find the extra details make it easier to read.
Reading a sequence diagram is very simple. Start at the top left corner with the "driver" class instance that starts the sequence. Then follow each message down the diagram. Remember: Even though the example sequence diagram in Figure 4 shows a return message for each sent message, this is optional.
By reading our sample sequence diagram in Figure 4, you can see how to create a CD Sales Report. The aServlet object is our example driver. aServlet sends a message to the ReportGenerator class instance named gen. The message is labeled generateCDSalesReport, which means that the ReportGenerator object implements this message handler. On closer inspection, the generateCDSalesReport message label has cdId in parentheses, which means that aServlet is passing a variable named cdId with the message. When gen instance receives a generateCDSalesReport message, it then makes subsequent calls to the CDSalesReport class, and an actual instance of a CDSalesReport called aCDReport gets returned. The gen instance then makes calls to the returned aCDReport instance, passing it parameters on each message call. At the end of the sequence, the gen instance returns aCDReport to its caller aServlet.
Please note: The sequence diagram in Figure 4 is arguably too detailed for a typical sequence diagram. However, I believe it is simple enough to understand, and it shows how nested calls are drawn. Also, with junior developers, sometimes it is necessary to break down sequences to this explicit level to help them understand what they are supposed to do.
The statechart diagram models the different states that a class can be in and how that class transitions from state to state. It can be argued that every class has a state, but that every class shouldn't have a statechart diagram. Only classes with "interesting" states — that is, classes with three or more potential states during system activity — should be modeled.
As shown in Figure 5, the notation set of the statechart diagram has five basic elements: the initial starting point, which is drawn using a solid circle; a transition between states, which is drawn using a line with an open arrowhead; a state, which is drawn using a rectangle with rounded corners; a decision point, which is drawn as an open circle; and one or more termination points, which are drawn using a circle with a solid circle inside it. To draw a statechart diagram, begin with a starting point and a transition line pointing to the initial state of the class. Draw the states themselves anywhere on the diagram, and then simply connect them using the state transition lines.
The example statechart diagram in Figure 5 shows some of the potential information they can communicate. For instance, you can tell that loan processing begins in the Loan Application state. When the pre-approval process is done, depending on the outcome, you move to either the Loan Pre-approved state or the Loan Rejected state. This decision, which is made during the transition process, is shown with a decision point — the empty circle in the transition line. By looking at the example, a person can tell that a loan cannot go from the Loan Pre-Approved state to the Loan in Maintenance state without going through the Loan Closing state. Also, by looking at our example diagram, a person can tell that all loans will end in either the Loan Rejected state or the Loan in Maintenance state.
Activity diagrams show the procedural flow of control between two or more class objects while processing an activity. Activity diagrams can be used to model higher-level business process at the business unit level, or to model low-level internal class actions. In my experience, activity diagrams are best used to model higher-level processes, such as how the company is currently doing business, or how it would like to do business. This is because activity diagrams are "less technical" in appearance, compared to sequence diagrams, and business-minded people tend to understand them more quickly.
An activity diagram's notation set is similar to that used in a statechart diagram. Like a statechart diagram, the activity diagram starts with a solid circle connected to the initial activity. The activity is modeled by drawing a rectangle with rounded edges, enclosing the activity's name. Activities can be connected to other activities through transition lines, or to decision points that connect to different activities guarded by conditions of the decision point. Activities that terminate the modeled process are connected to a termination point (just as in a statechart diagram). Optionally, the activities can be grouped into swimlanes, which are used to indicate the object that actually performs the activity, as shown in Figure 6.
In our example activity diagram, we have two swimlanes because we have two objects that control separate activities: a band manager and a reporting tool. The process starts with the band manager electing to view the sales report for one of his bands. The reporting tool then retrieves and displays all the bands that person manages and asks him to choose one. After the band manager selects a band, the reporting tool retrieves the sales information and displays the sales report. The activity diagram shows that displaying the report is the last step in the process.
A component diagram provides a physical view of the system. Its purpose is to show the dependencies that the software has on the other software components (e.g., software libraries) in the system. The diagram can be shown at a very high level, with just the large-grain components, or it can be shown at the component package level. [Note: The phrase component package level is a programming language-neutral way of referring to class container levels such as .NET's namespaces (e.g., System.Web.UI) or Java's packages (e.g., java.util).]
Modeling a component diagram is best described through an example. Figure 7 shows four components: Reporting Tool, Billboard Service, Servlet 2.2 API, and JDBC API. The arrowed lines from the Reporting Tool component to the Billboard Service, Servlet 2.2 API, and JDBC API components mean that the Reporting Tool is dependent on those three components.
The deployment diagram shows how a system will be physically deployed in the hardware environment. Its purpose is to show where the different components of the system will physically run and how they will communicate with each other. Since the diagram models the physical runtime, a system's production staff will make considerable use of this diagram.
The notation in a deployment diagram includes the notation elements used in a component diagram, with a couple of additions, including the concept of a node. A node represents either a physical machine or a virtual machine node (e.g., a mainframe node). To model a node, simply draw a three-dimensional cube with the name of the node at the top of the cube. Use the naming convention used in sequence diagrams: [instance name] : [instance type] (e.g., "w3reporting.myco.com : Application Server").
The deployment diagram in Figure 8 shows that the users access the Reporting Tool by using a browser running on their local machine and connecting via HTTP over their company's intranet to the Reporting Tool. This tool physically runs on the Application Server named w3reporting.myco.com. The diagram shows the Reporting Tool component drawn inside of IBM WebSphere, which in turn is drawn inside of the node w3.reporting.myco.com. The Reporting Tool connects to its reporting database using the Java language to IBM DB2's JDBC interface, which then communicates to the actual DB2 database running on the server named db1.myco.com using native DB2 communication. In addition to talking to the reporting database, the Report Tool component communicates via SOAP over HTTPS to the Billboard Service.
Although this article provides only a brief introduction to Unified Modeling Language, I encourage you to start applying the information you have learned here to your own projects and to dig more deeply into UML. There are several software tools that help you to integrate UML diagrams into your software development process, but even without automated tools, you can use markers on a whiteboard or paper and pencils to draw your UML diagrams and still achieve benefits.
This post is originally posted by Donald Bell at IBM developerWorks | <urn:uuid:e2d1cfcb-f39b-4e5f-902b-7091a6496345> | 3.046875 | 3,230 | Personal Blog | Software Dev. | 43.060962 | 95,534,950 |
Once upon a time a guy named Roy Fielding made his disertation about a design aproach called REST. From this point REST is getting very popular. Many service provider using REST to offer developers access to their services i.e. Twitter, Facebook and so on.
But what is this REST thing? It’s a way to publish web services without any overloaded technology like SOAP for example. Every REST service is available under a unique URL and can accessed by everybody. Mostly it sends a response using XML but this is different from service to service. To get the idea of REST let’s take a look at an example. There is a realy huge REST example out there. Probably you using it every day – it’s called the World Wide Web 😉
Yes, the web is nothing else as an landscape full of REST web services. Mostly the services response are HTML but as I said before the response can vary from service to service.
The special thing about REST is that it uses a very well known technology called HTTP. Fielding was involved in the design of HTTP1.1. So REST is nothing else as a way to use HTTP the right way. The HTTP methods (GET, PUT, DELETE, UPDATE) are used for the interaction. The benefit for us developers is, that we can use any programming language to access such a REST service.
And why does ECF want to kiss REST? As I said before, many providers already provide RESTful interfaces. So if ECF has a common API to access a REST based web service it would be much easier to implement providers for these services. On this point GSoC enters the field.
There is a GSoC project called “REST abstraction for ECF” which is my project for this year. You can read more about this project in my proposal and edit or update ideas. Please feel free to get involved.
The overall goal for this project is to make the Eclipse IDE more social. Sounds terrifying isn’t it? But imagine, you open your workspace and activate a mylyn task which is probably a bug. On the same time the bug id and your name is tweeted on Twitter. So everybody who’s interested in your project can see that you working on a new feature or bug. I think this would be really awesome to improve collaboration. There are many other use cases, if you have any ideas please feel free to add comments. Maybe we can realize it if the project has finished. There is only one hurdle left.
The project has to be nominated. So if you are a mentor for GSoC2009, please vote for this project and on the same time for me. Every vote counts 😉
Thank you all for your interest.
Latest posts by Holger Staudacher (see all)
- An Apache Cordova hook to auto bump iOS CFBundleVersion and Android versionCode - April 7, 2015
- Brand your Tabris.js app - April 2, 2015 | <urn:uuid:37afd660-19df-4b76-966e-4189b918ae94> | 2.75 | 621 | Personal Blog | Software Dev. | 61.099107 | 95,534,955 |
Environmental Conservation for Development in Central America
Conservation in Central America has recently taken the step from protection of wildlife to a wider concept of safeguarding the integrity of the environment in order to attain ecologically and economically sound development. The focus is on translating the concepts of natural resource management, conservation and sustainable development into practical programmes for action through local institutions. Conservation is not seen as a separate sector but as a concept unifying different sectors of society including government and non-governmental organizations. This article chronicles the implementation of the International Union for Conservation of Nature’s (IUCN’s) regional programme for Central America. The programme, which is based on the World Conservation Strategy, covers tropical rain forests, coral reefs, lagoon systems, coastal wetlands and mangrove forests, and initiates and coordinates projects that demonstrate the link between conservation and development. Environmental impact assessments, institution building, and human resources development are other components of the programme.
KeywordsMangrove Forest Coastal Wetland Assessment Environmental Impact Environmental Impact Assessment Wildlife Refuge
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This blog is a record of my learning at Pt England School through to Tamaki College.
Thursday, 13 November 2014
Solar Energy: The Power of the Sun
We are learning to use relevant parts of the text to accurately answer the questions.
How is it possible to use solar energy from solar panels at night?
So it can be sunlight.
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A storm of tiny dust particles has engulfed Mars over the last two weeks and prompted NASA’s Opportunity rover to suspend science operations. But across the planet, NASA’s Curiosity rover, which has been studying Martian soil at Gale Crater, is expected to remain largely unaffected by the dust. While Opportunity is powered by sunlight, which can’t penetrate the dust at its current location, Curiosity has a nuclear-powered battery that runs day and night.
Martian dust storms are common, especially during southern hemisphere spring and summer, when the planet is closest to the Sun. As the atmosphere warms, winds generated by larger contrasts in surface temperature at different locations mobilize dust particles the size of individual talcum powder grains. Carbon dioxide frozen on the winter polar cap evaporates, thickening the atmosphere and increasing the surface pressure. This enhances the process by helping suspend the dust particles in the air. In some cases, the dust clouds reach up to 40 miles (60 kilometers) or more in elevation.
Though they are common, Martian dust storms typically stay contained to a local area. By contrast, the current storm, if it were happening on Earth, would cover an area bigger than North America and Russia combined.
Image 1. This self-portrait by NASA's Curiosity rover was taken on June 15, 2018
Image 2 and 3. These two views from NASA's Curiosity rover, acquired specifically to measure the amount of dust inside Gale Crater, show how much dust increased over three days. Image 2 shows a view of the east-northeast rim of Gale Crater on June 7, 2018; image 3 shows a view of the same feature on June 10, 2018. The images were taken by the rover's Mastcam.
Credit: NASA #nasagoddard #mars #space #science #storm #dust #rover #NationalSelfieDay | <urn:uuid:fb37417c-fb60-4d94-88fc-0172a73a7500> | 4.15625 | 381 | News Article | Science & Tech. | 42.844078 | 95,535,013 |
Physiological time and the growth of the universe.
Frank Russo - November 07 2010.
The mass defect in nuclear fusion, is the key that hints how the growth of the universe might take place. In a recent idea/paper, I outlined how gravity might fuse nuclei together at the centre of stars, galaxies and other entities... and at the same time fuse some space into the resultant bigger nuclei so that the universe can grow.
However the key ingredient to all this is the principle of physiological time. In essence, the fact that gravity slows down by '10 to the 40', as we move up one level to where the size of our universe is like one of our atoms is to us - to the there sentient beings... actually means that one of our atoms would appear to weigh '10 to the 40' times more in that realm... remember 'work" is equal "distance times force", and every meter one level up is the equivalent of '10 to the 40' metres from our level!
Hence as you move outwards from our level and into a much bigger universe, one can actually dilute matter so much so that one could possibly make '10 to the 40' atoms from one of "our" atoms... the much longer physiological time would act to make the electrons be everywhere at 'once'... and by being much more distant from the centre, one would have a much bigger atom... this fits in very well with the fact that atoms are made up of mainly 'space'! Remember some particles can go straight through our earth without actually bumping into anything!
This is all food for thought... and although the concept of a universe growing like a fractal, might need some further refining... I think I'm on the right track. | <urn:uuid:488ab19a-448f-4344-a308-621e18e8273d> | 2.859375 | 358 | Personal Blog | Science & Tech. | 67.041727 | 95,535,028 |
South African city Gansbaai has been known to be one the the worlds locations with the highest clustering of white shark populations. This region alone used to have about 2,000 great white sharks but it has been recently found that that number could actually be far below what it should be. The Dyer Island Conservation Trust finds that the great white population is actually lower than that meaning that they should now be classified as a threatened specie.
They way that they came about these numbers was by cataloging the dorsal fin of each white shark. Interestingly, each shark has a unique dorsal fin. Examples of the uniqueness can be described as wolfgang (pointed top with ridges), notch, and slash fin (which looks like chunks are missing from the fin). Through the collaboration of the Dyer Island Conservation Trust and the Marine Shark Cage Diving company, marine biologists were able to shoot aver 20,000 pictures of great white fins. They then compiled all of the pictures and were able to identify 532 sharks.
With an algorithm they found that there are only a maximum 1,000 inhabiting the waters pif Gansbaai. With numbers like these, the initiatives to help preserve this amazing species are closely monitored and advocated for. [via]6.5k | <urn:uuid:d972ba14-06c2-435a-915d-f084f9719740> | 3.5 | 260 | Truncated | Science & Tech. | 51.096113 | 95,535,030 |
Through Einstein's Eyes web site is the online version of a multimedia project based around how things look at relativistic speeds. It is aimed at high school to early university level physics students.
There are two sections. One is fun and spectacular, with a relativistic roller coaster ride and a tour of the solar system. The other explores the physics of special relativity.
CD and DVD versions of the material are available, and are helpful because of the large size of some of the video files.
Please note that this resource requires
9-12: 10C/H1. As a young man, Albert Einstein, a German scientist, formulated the special theory of relativity, which brought about revolutionary changes in human understanding of nature. Among the counterintuitive ideas of special relativity is that the speed of light is the same for all observers no matter how they or the light source happen to be moving. In addition, nothing can travel faster than the speed of light.
9-12: 10C/H6. Under everyday situations, most of the predictions of special relativity are nearly identical to those of classical mechanics. The more counterintuitive predictions of special relativity occur in situations that humans do not typically experience.
11. Common Themes
6-8: 11B/M4. Simulations are often useful in modeling events and processes.
9-12: 11B/H1a. A mathematical model uses rules and relationships to describe and predict objects and events in the real world.
9-12: 11B/H2. Computers have greatly improved the power and use of mathematical models by performing computations that are very long, very complicated, or repetitive. Therefore, computers can reveal the consequences of applying complex rules or of changing the rules. The graphic capabilities of computers make them useful in the design and simulated testing of devices and structures and in the simulation of complicated processes.
%0 Electronic Source %A Savage, Craig %D June 22, 2005 %T Through Einstein's Eyes Online - Visualizing Special Relativity %V 2018 %N 22 July 2018 %8 June 22, 2005 %9 video/quicktime %U http://people.physics.anu.edu.au/~cms130/TEE/
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Representing magnitude information in various dimensions, including space, quantity, and time, is an important function of the human brain. Many previous studies reported that numerical and spatial magnitudes could be mutually influenced through a " mental number line " . In this study, we address the question of whether magnitudes in nontemporal dimensions and magnitudes in time are represented independently or not. Observers judged the duration of the stimuli while four types of nontemporal magnitude information, including number of dots, size of open squares, luminance of solid squares, and numeric value of digits, were manipulated in Stroop-like paradigms. Results revealed that stimuli with larger magnitudes in these nontemporal dimensions were judged to be temporally longer. This observation supports the idea that magnitudes in temporal and nontemporal dimensions are not independent and implies the existence of generalized and abstract components in the magnitude representations.
Mendeley saves you time finding and organizing research
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