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"We were getting ready for a routine engineering run when all of a sudden the nova went off. It was very bright and easy to observe, so we took this opportunity and turned it into gold," says team member Marc Kuchner of NASA’s Goddard Space Flight Center in Greenbelt, Md.
Kuchner and his colleagues used the "nulling" mode of the Keck Interferometer, which is part of the NASA-funded Keck Interferometer. This state-of-the-art instrument combines starlight using two 10-meter (33 feet) telescopes. In the nulling mode, the interferometer suppresses the blinding light of a star so researchers can study the surrounding environment. The instrument helps researchers observe very faint objects near bright sources and produces ten times more resolving power than a single Keck telescope working alone. It is the only instrument of its kind in operation.
The Keck Nuller was undergoing tests on February 12, 2006, when a nova flared up in the constellation Ophiuchus. The system, known as RS Ophiuchi, consists of a white dwarf and a red giant. The red giant is gradually shedding its massive gaseous outer layers, and the white dwarf is sweeping up much of this wind, growing in mass over time. As the matter builds up on the white dwarf’s surface it eventually reaches a critical temperature that ignites a thermonuclear explosion that causes the system to brighten 600-fold. RS Ophiuchi was previously seen to blow its stack in 1898, 1933, 1958, 1967, and 1985, so astronomers were eagerly anticipating the 2006 eruption.
Just 3.8 days after the nova was detected, the group observed the explosion with the Keck Nuller. The team set the instrument to cancel out the nova’s light, allowing the group to see the much fainter surrounding material. The group next adjusted the nuller to observe the extremely bright blast zone.
The instrument’s versatility was key to a surprising discovery. The nuller saw no dust in the bright zone, presumably because the nova’s blast wave vaporized dust particles. But farther from the white dwarf, at distances starting around 20 times the Earth-Sun distance, the nuller recorded the spectral signature of silicate dust. The blast wave had not yet reached this zone, so the dust must have pre-dated the explosion.
"This flies in the face of what we expected. Astronomers had previously thought that nova explosions actually create dust," says Richard Barry of NASA Goddard, lead author of a paper on the Keck observations that will be published in the Astrophysical Journal.
The team thinks the dust is created as the white dwarf plows through the red giant’s wind, creating a pinwheel pattern of higher-density regions that is reminiscent of galaxy spiral arms. Inside these spiral arms, atoms reach low enough temperatures and high enough densities to allow atoms to stick together to form dust particles. The nova’s blast wave has since destroyed RS Ophiuchi’s pinwheel pattern, but it should re-form over the next few years, and future Spitzer Space Telescope observations could see it.
Most studies of RS Ophiuchi have relied on spectroscopic models, but those methods have not been able to distinguish various nova components with as much detail as the interferometer. The Keck Nuller measured one component of the RS Ophiuchi system to an accuracy of just 4 milliarcseconds, or about the size of a basketball seen 7,500 miles away.
Barry is also coauthor of a paper based on Spitzer observations of RS Ophiuchi. This paper reports independent evidence for silicate dust that predates the 2006 explosion.
"The RS Ophiuchi observations are just a small taste of the power and potential we expect from the Keck Nuller," says coauthor William Danchi of NASA Goddard. "But ultimately we want to launch a nulling interferometer into space to image extrasolar planets. These Keck results are a technological and scientific pathfinder toward that future."
Robert Naeye | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
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The St. Petersburg researchers suggest that infrared emission should be used to treat burns. The Foundation for Assistance to Small Innovative Enterprises (FASIE) will help the authors in the framework of the “Start” program to develop and begin production of devices required for such treatment based on silicon light-emitting diodes.
A unique device based on silicon light-emitting diodes was developed by the St. Petersburg physicists – specialists of the Ioffe Physico-Technical Institute, Russian Academy of Sciences, and the St. Petersburg State Electrotechnical University. Emission of far infra-red range of wave-lengths generated by this device will help to cure in an ordinary hospital even such burns that could be previously treated only in specialized burn centers. The Foundation for Assistance to Small Innovative Enterprises (FASIE) will help the researchers to arrange production of remarkable devices.
“The fact that the far infrared emission promotes quicker healing of burns can be considered ascertained, says project manager, Professor Bagrayev, Doctor of Science (Physics&Mathematics). We have already made sure of that through applying the small-size device developed by us, which proved well in treating arthrosis, wounds, ulcers and bedsore. It has turned out that in case of burns the device helps very efficiently: affected surface heals quicker and hurts less. However, irradiation of a large surface accordingly requires the radiation source of a larger flat area than the one previously used.
Sergey Komarov | alfa
What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
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MRI Physics – Resonance – Deconstructing MRI Physics Test Review.
In our previous article we discussed atoms, their subatomic particles, as well as the three distinct spins occuring within the atom. We also covered the terms Magnetic Moment, Precession, Net Magnetization Vector, as well as defined the Larmor Equation and broke it down into easily digestible steps and terms. In this article we will discuss the concept of Resonance, and its relation and importance in MRI.
In physics, resonance is a process in which a vibrating object or external force causes another system to vibrate with greater amplitude at specific frequencies. While this definition may sound somewhat dense, as is the case with many things in MRI, it can be broken down into simpler terms. This can be thought of as follows: if a force is vibrating at a certain frequency and it comes into contact with a seperate force vibrating at a similar frequence, that second force will become excited and gain energy.
Such excitation is on of the fundamental aspects of MRI.
In MRI the “external force” causing all of the excitement discussed above is a radiofrequency (RF) pulse and the “other system” gaining energy, becoming excited, is the precessing hydrogen atoms nucleus. If we recall from the previous article, hydrogen is precessing in accordance to the Larmor Equation. For every 1T of external magnetic field strength, hydrogen precesses at 42.57MHz or millions of times per second. If we send in a vibrating object, in this case a radiofrequency pulse, at a similar frequency to this precession, resonance should, and does occur. If, however, radiofrequency is sent in at a frequency different to the precessional frequency of the hydrogen atom, resonance and excitation will not occur. It is also important to note that 42.57MHz/T is the precessional frequency of hydrogen, but other elements have their own individual precessional frequencies, and as such when RF is sent in at the precessional frequency of hydrogen, these atoms do not achieve resonance, or excitation. Conversely, RF sent in at the precessional frequency of these other atoms will have no effect on hydrogen.
You may also recall from the previous article that the Net Magnetization Vector is a byproduct of an excess of low energy (parallel, spin up) hydrogen atoms. In using the analogy of a lazy river at a waterpark, we discussed how there will be more low energy, lazy patrons who are willing to be pulled by the current of the river than there are patrons attempting to swim against the current. This excess of low energy patrons, or in the case of MRI, precessing hydrogen atoms, are what compose the net magnetization vector. This NMV is, prior to excitation, is pointing north, or upward Y axis of an XY axis graph.
The introduction of RF at the resonant frequency of hydrogen causes excitation, and some of the hydrogen atoms that were previously spin up, north oriented, low energy prior to excitation, gain energy and transition into a spin down, high energy state. The introduction of RF at hydrogens resonant frequency and the excitation caused can be thought of as analogous to introducing energy drinks to the patrons in the lazy river. While many of the patrons will continue to lazily be pulled by the flow of the river, a few will find motivation from the new found energy and decide to swim against the current. This shift in hydrogen nuclei (patrons) will cause a shift in the Net Magnetization Vector, tilting it away from north on the Y axis of our XY axis graph. The tilt of this vector away from north on the Y axis can vary in its degrees of flip and is known as the Flip Angle. Flip Angle’s vary by pulse sequence which will be discussed in a future article, but for a point of reference common flip angles for Gradient Echo Sequences typically range between 1 and 89 degrees. Common values for Spin Echo Sequences are 90 and 180 degrees.
The XY graph described above, when pertaining to MRI, has unique names for the X and Y axis. The Y axis, which the Net Magnetization Vector is typically oriented toward in the presence of an external magnetic field, prior to excitation by an RF pulse, is known as the longitudinal plane. The X axis in MRI is referred to as the Transverse plane. Upon receiving excitation from an RF pulse the Net Magnetization Vector flips itself toward the transverse plane, and away from the longitudinal plane.
It is also important to note that the Radio Frequency pulse causing excitation and resonance must come in perpendicular to the angle of the Net Magnetization Vector. Again reinforcing our lazy river analogy, an energy drink thrown from behind cannot be caught by the lazy river patron. One being thrown from the front could potentially come in too fast and hit the patron in the head. An energy drink gently tossed from the side however would be easily caught and cause excitation, and resonance.
One final item of importance regarding excitation and resonance in MRI is the concept of Phase. When the net magnetization vector becomes excited, its protons begin to precess in-phase. This can be thought of as follows: prior to excitation from their energy drinks all of our patrons in the lazy river were pointed either directly with, or directly against the current of the lazy river. These patrons were all spinning, or precessing, at the same rate in their inner tubes, but were spinning independently from one another. While patrons were spinning at the same speed, one could be facing to the right while another could be facing to the left. Patrons who are spinning at the same rate, but have different orientation are out-of-phase from one another. In the presence of an RF pulse, which produces excitation or resonance, however, these patrons or independent magnetic moments would all align themselves with one another and spin at the same frequency, and have the same orientation. This means that all patrons would be spinning at the same rate in the lazy river, and would all be facing the same directing at the same time. This level of choreography from our patrons is short lived, however, and as soon as the RF pulse or energy drinks are removed our patrons begin to lose phase, and transition back into their natural out-of-phase state. | <urn:uuid:539df5f9-3bf7-4133-9023-b4973009ee4c> | 3.1875 | 1,307 | Truncated | Science & Tech. | 37.525407 | 95,516,455 |
In a collaborative effort involving 74 researchers from 38 research institutes, scientists have produced the full genome of a wild strawberry plant. The research appeared today in Nature Genetics. Drs. Asaph Aharoni and Avital Adato of the Weizmann Institute’s Plant Sciences Department were the sole Israeli scientists participating in the project, but they made a major contribution in mapping the genes and gene families responsible for the strawberry’s flavor and aroma.
The woodland strawberry (Fragaria vesca) is closely related to garden-variety cultivated strawberry. The fruit of this berry contains large amounts of anti-oxidants (mainly tannins, the substances that give wine their astringency), as well as vitamins A, C and B12 and minerals – potassium, calcium and magnesium. In addition, the strawberry fruit is uniquely rich in substances for flavor and aroma.
Participation in this project is something of a circle closer for Aharoni: For a number of years he has been investigating the metabolic pathways of ripening, in which the substance that give the fruit its flavor and aroma are produced. Aharoni was one of the first to use biological chips to analyze the genetic networks involved in creating these substances. He has also conducted a comparative analysis of these genes in wild and cultivated plants, looking for the differences. Now that the full genome of the wild strawberry plant is available for research, he is able not only to conduct deeper and broader investigations, but to shed new light on some of his past findings. Thus, for instance, in carrying out a computerized analysis of the woodland strawberry genome, Adato was able to place an enzyme that Aharoni had previously characterized in a relatively small enzyme family. This small family is responsible for the production of a large number of aromatic substances, and the finding helped clarify their means of production.
Aharoni hopes that, among other things, the newly sequenced genome will help scientists understand how to return the flavors and aromas that have been lost over years of breeding in the cultivated cousin of the wild strawberry. The intense, concentrated aroma and flavor of the woodland strawberry are, he says, something to aspire to.
The woodland strawberry has now joined the elite list of plants, including rice, grapes and soya, which have had their genomes sequenced. The length of the genome is about 240 million bases and contains around 35,000 genes. (In comparison, the human genome has three billion bases, but only 23,000 genes.) The woodland strawberry genome is relatively short, simple and easy to manipulate, and the plant grows quickly and easily. These qualities make it an ideal model plant that might provide insight into other related agricultural crops (the rose family) including cultivated strawberries, and such fruit trees as apples peaches, cherries and almonds.
Dr. Asaph Aharoni’s research is supported by the De Benedetti Foundation-Cherasco 1547; the Minna James Heineman Stiftung; the Willner Family Foundation; and Roberto and Renata Ruhman, Brazil. Dr. Aharoni is the incumbent of the Adolpho and Evelyn Blum Career Development Chair of Cancer Research.
The Weizmann Institute of Science in Rehovot, Israel, is one of the world's top-ranking multidisciplinary research institutions. Noted for its wide-ranging exploration of the natural and exact sciences, the Institute is home to 2,600 scientists, students, technicians and supporting staff. Institute research efforts include the search for new ways of fighting disease and hunger, examining leading questions in mathematics and computer science, probing the physics of matter and the universe, creating novel materials and developing new strategies for protecting the environment.
Weizmann Institute news releases are posted on the World Wide Web at http://wis-wander.weizmann.ac.il, and are also available at http://www.eurekalert.org.
Batya Greenman | idw
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
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Amazon Rainforest Facts for Kids Video
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Electrode Processes with Antecedent Protonation Reaction
In electrochemical processes at the mercury electrode involving organic compounds, hydrogen ion addition or release usually takes place (an example of the very few electrode processes in which hydrogen ions do not take part is the reduction of aliphatic derivatives of vicinal dihalogen compounds: after the transfer of two electrons, two halogen ions are released and a multiple bond is formed between the carbon atoms [468–472]). On electrodes having a small hydrogen overvoltage the hydrogen atoms adsorbed on the electrode can take part in the electrode process (see, for example, ).
KeywordsMaleic Acid Reaction Layer Proton Donor Nitro Compound Electrode Process
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Authors: Nainan K. Varghese
Light is sensed by rational beings. Only real entities can produce sensory perception. Matter alone provides substance needed for objective reality in space. Hence, light or its components are essentially made of matter. Universal medium (formed by matter), under suitable conditions, creates components of light from itself. For existence, it is essential for light’s components to move at the highest possible linear speed, at which universal medium can move them and spin at frequency, proportional to their matter-contents. Flow of these components constitutes radiation of light or similar radiations. This essay very briefly describes mechanism of creation and development of light’s components, as envisaged in alternative concept, presented in the book, ‘MATTER (Re-examined)’. For details, kindly refer same .
Comments: 6 Pages. Published in General Science Journal
[v1] 2013-12-18 08:27:16
Unique-IP document downloads: 473 times
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SAN FRANCISCO, Nov. 13 (Xinhua) -- Many of birds in the western U.S.state of California are breeding five to 12 days earlier than they did 75 to 100 years ago, a new study led by a University of California Berkeley (UC Berkeley) researcher showed Monday.
The study, to be published online for the Nov. 13 week by the journal Proceedings of the National Academy of Sciences, compared nesting data from the early 1900s to similar data today and found that California birds are nesting earlier to avoid warmer weather.
More than 200 species of California birds were examined for their overall nesting behaviors in the study led by former UC Berkeley graduate student Morgan Tingley, now an assistant professor at the University of Connecticut in Storrs.
Past research found that not all California birds in mountains would be migrating north or to higher elevations for cooler temperatures as a result of global warming.
In the past decades, higher temperatures have prompted early arrivals of spring, a phenomenon long observed by the general public, which resulted in plant leaves and seeds growing earlier and insects emerging earlier.
The leaves, seeds and insects are an important source of birds' food, which would affect the birds' pattern of nesting.
The latest study, a UC Berkeley press release Monday said, highlighted an interesting discovery. While nesting one week earlier, birds produce eggs at a temperature about 1 degree Celsius lower if they do at the normal time in the same place.
"By nesting a week or 10 days earlier, birds are avoiding some of the negative effects of climate warming," Professor Steven Beissinger was quoted by the press release as saying.
Beissinger, also a co-author of the study, is a UC Berkeley professor of environmental sciences, policy and management. | <urn:uuid:4a8586c2-9848-423f-b6b5-eb99e599ded1> | 2.796875 | 361 | News Article | Science & Tech. | 39.175227 | 95,516,513 |
- Open Access
The symbiotic magnetic-sensing hypothesis: do Magnetotactic Bacteria underlie the magnetic sensing capability of animals?
© The Author(s). 2017
Received: 16 August 2017
Accepted: 2 October 2017
Published: 23 October 2017
The ability to sense Earth’s magnetic field has evolved in various taxa. However, despite great efforts to find the ‘magnetic-sensor’ in vertebrates, the results of these scientific efforts remain inconclusive. A few decades ago, it was found that bacteria, known as magnetotactic bacteria (MTB), can move along a magnetic field using nanometric chain-like structures. Still, it is not fully clear why these bacteria evolved to have this capacity. Thus, while for MTB the ‘magnetic-sensor’ is known but the adaptive value is still under debate, for metazoa it is the other way around.
In the absence of convincing evidence for any ‘magnetic-sensor’ in metazoan species sensitive to Earth’s magnetic field, we hypothesize that a mutualism between these species and MTB provides one. In this relationship the host benefits from a magnetotactic capacity, while the bacteria benefit a hosting environment and dispersal. We provide support for this hypothesis using existing literature, demonstrating that by placing the MTB as the ‘magnetic-sensor’, previously contradictory results are now in agreement. We also propose plausible mechanisms and ways to test the hypothesis. If proven correct, this hypothesis would shed light on the forces driving both animal and bacteria magnetotactic abilities.
The geomagnetic field is an omnipresent feature of Earth. It is therefore not surprising that various organisms, including invertebrates, vertebrates and bacteria, use magnetotactic abilities for orientation and navigation [1–6]. Magnetoreception has been of significant scientific interest [1, 5, 7–9] both for its navigation-based capacity as well for other uses [5, 10]. Intensive work has demonstrated the existence of magnetic sensing and its possible function in animal navigation [11–13]. Earth’s magnetic field is rather weak, with 60–65 μT at the poles, and 25–30 μT near the equator . To put this in perspective, a standard fridge magnet produces a magnetic force that is ~200 times stronger. Thus, sensing a magnetic field as weak as the Earth’s is challenging. Most of magnetoreceptive animals sense the magnetic field’s inclination angle, meaning the magnetic field lines, rather than the magnetic field polarity, i.e. north and south [1, 8, 13]. This provides the animal with a proxy for its latitude, an essential measure for wandering or long-distance migrating animals. The ability of animals to sense the magnetic field’s inclination angle has been well documented for over 40 years and has been reported in various taxa across the animal kingdom including fish , insects and apparently all tetrapods except mammals, e.g. reptiles and birds ;reviewed in ref. . However, the sensor and sensory mechanism behind this remain an enigma and are widely debated. In vertebrates, for example, it has been suggested that the ‘magnetic-sensor’ or sensing organ is located in the ethmoid region of the head, between the eyes orbits and the naris [17–19].
Support and criticism for the “radical-pair” and “magnetite-based” magnetoreception hypotheses
Experiments showing that birds can only sense the magnetic field under illumination with relative short wavelength, as opposed to longer wavelengths
The effect of the magnetic field on the spin-state of the molecule has not been demonstrated, either in vitro or in vivo, under the Earth’s weak magnetic field, but only under a field orders of magnitude stronger [20, 47]
The activation mechanism is missing, meaning how the signal transduces to initiate a neural response.
No one has seen magnetite crystals serving as a ‘magnetic-sensor’ except in bacteria
The activation mechanism is missing, meaning how the signal transduces to initiate a neural response.
In contrast to all other organisms, an unequivocal demonstration of the use of the geomagnetic field’s inclination angle for orientation was found in magnetotactic bacteria (MTB). Magnetotactic bacteria (MTB) are a diverse group of aquatic prokaryotes, ubiquitously found in both fresh and marine sediment habitats. MTB show magnetotaxis - the ability to align with a magnetic field using specialized intracellular organelles called magnetosomes . In most MTB, magnetosomes comprise chain-like, nanometer-sized crystals (typically between 35 and 120 nm) of magnetic iron minerals . It has been suggested that the magnetotaxis redirects MTB towards an anaerobic environment . In aquatic environments, there are opposing gradients of oxygen and sulfide from the surface to the bottom of the sediment, which create an oxi-anoxic transition zone (OATZ). Most MTB prefer to reside at, or close to, the OATZ. While recent experiments support the general assumption that MTB use the magnetic field to vertically locate the OATZ [24, 25] there are a few unresolved issues with this model. For example, MTB recognize and move along the oxygen gradient even if the magnetic cue directs them against it . In addition, some MTB produce a large number of magnetosomes, far greater than would be needed to align along Earth’s magnetic field . Finally, MTB have been found at, or near the equator, where magnetotaxis has no advantage in directing vertical movement, as the inclination angle is ~0° . These confounding observations elicited the formulation of alternative hypotheses as to the possible advantages gained by MTB through the production of magnetosomes, yet none of these hypotheses have been proven conclusive . Although the adaptive value of MTB’s magnetotaxis is still under some debate, MTB’s ability to act upon the magnetic field inclination angle is well established.
In contrast to MTB, no one has directly observed magnetite crystals serving as a ‘magnetic-sensor’ in animals . This is despite repeated reported observations of magnetite crystals, in various taxa [1, 2, 18].
The symbiotic magnetic-sensing hypothesis and suggested mechanisms
Our hypothesis is derived from the magnetite-based magnetoreception hypothesis. As mentioned above, magnetite crystals have been found in a large number of organisms [2, 20, 28], including birds , and have been described as being “strikingly similar to the MTB crystals” . However, magnetite crystals have not convincingly been located within bird tissues or neuron cells [30–32] but instead appear to be extracellular contamination or within macrophages . Interestingly, it is known that macrophages engulf commensal bacteria, so it is possible that these crystals may have originated from MTB.
The magnetite-based magnetoreception hypothesis requires magnetite to be organized in a chain-like manner , similar to that seen in MTB, as the crystals individually are too small to contribute to effective magnetoreception. The majority of magnetic-sensing animals use an inclination compass, as MTB do. This similarity may be because MTB underlie the animal’s inclination sensing capacity; alternatively, the capacity may have evolved independently in both kingdoms. In addition, the ubiquity of MTB means that the host is constantly exposed to them.
Previous studies have suggested that the magnetic sensing organ is located in the ethmoid region of the head . Within the eye orbit, there are several glands such as the Harderian and other lacrimal glands . The primary function of these glands is bathing and lubricating the eye, but they also serve other functions including photoreception, immunocompetence and habitats for endosymbiotic bacteria [34, 35]. The lacrimal glands also secret substances to the naris or the eye, such as hormones, porypherins and symbiotic bacteria [34, 35].
Studies have shown that a complex nerve system, whose function is unknown, runs through the glands and is associated with the ophthalmic nerve, e.g. ref. . Sectioning of the ophthalmic nerve impairs birds’ magnetic sensing , while other works support a role for the visual system [37, 38]. The Harderian gland surrounds the ophthalmic nerve, thus experiments sectioning that nerve have impaired the nerves that are connected to the gland.
There are several plausible mechanisms by which the MTB and host may communicate, enabling the host to sense the magnetic field. One possible mechanism is by the bacteria moving and accumulating at a specific location on the gland, allowing cell-to-cell communication. Whether the MTB move passively or actively in response to the magnetic field, their movement and/or accumulation could be detected by the host (Fig. 1). Interestingly, most MTB show exceptionally high number of proteins that are predicted to have functions in chemotaxis, sometimes order of magnitude higher than other types of bacteria . These secretions may excite a specific nerve connected to the ophthalmic nerve, passing on information to the host about the Earth’s magnetic field. This type of communication between commensal bacteria and the host nervous system has been shown in various animal systems .
A different mechanism by which the host could detect the MTB movement could be through the host’s visual system. For example, secreted bacteria from the lacrimal glands may move along the cornea. This movement could be perceived by the visual system similarly to the way in which humans perceive blood droplets movement along the cornea. It has been shown that birds sense the magnetic field under illumination of a relative short (443-550 nm), but not long (630 nm), wavelength , which means that the detection of small objects such as bacteria is a valid possibility. It should be noted that these experiments have been proposed to support the “radical–pair” hypothesis . Collectively, the “radical-pair” supporting experiments are not in conflict with the possibility of MTB being the underline mechanism of animals’ magnetic sensing. In fact, MTB magnetic orientation is also affected by light: green light decreases the translation velocity whereas red light increases it, in comparison to blue and white light .
The results from experiments in which an animal’s magnetic sensing has been manipulated are consistent with both proposed mechanisms [19, 37, 38, 41] as sectioning of the ophthalmic nerve may alter sensing or secretion of bacteria from the gland. Similarly, lack of illumination may affect magnetic sensing by making bacteria less detectable or reducing the secretory response within the gland .
Handling and isolating anaerobe MTB requires dedicated methods . Naturally, previous studies aiming to detect magnetite in metazoan used methods that were not suitable for identifying MTB, yet recent methodological progress (e.g. magnetoscope) should aid in bridging this gap [32, 43]. Recent progress in molecular methods has greatly increased the knowledge of genes that regulate magnetosome formation [39, 44]. These genes could potentially serve to detect symbiotic MTB. However, due to their polyphyletic nature and great variation , to date there is no general primer set which would enable the detection of all MTB species.
It was well established that animals’ behavior can be manipulated by microorganisms. For example, recent evidence show that the gut microbiota integrate into the gut–brain axis interact to change brain function , or the multitude effect of parasites on the hosts’ personality and behavior . We predict that similar mechanisms between the host and the microorganism exist to generate the magnetic sensing capability in birds and possibility other animals.
Previously, the presence of magnetite in many animals and fossils, led Kirschvink et al. to hypothesize that magnetite crystals may have been intra-cellularly incorporated, similarly to the endosymbiosis incorporation of mitochondria billions of years ago . Here, we suggest that extant animal magnetotactic abilities are still endosymbiont, meaning the bacteria reside side by side to the eukaryote cells.
The proposed symbiotic magnetic sensing hypothesis can be proved or refuted experimentally using an approach similar to Koch’s Postulates. If proved correct, this hypothesis will shed light on the ecological and evolutionary forces driving, maintaining, and shaping magnetic-sensing abilities for both bacteria and animals, solving a long-lasting scientific mystery.
The authors would like to thanks Uri Grodzinski, Yohay Carmel, Jennifer Handsel, Arnon Lotem, and Michal Arbilly for helpful suggestion and critical reading. And to Christopher Lefevre and Orr Shapiro for helpful discussions, and to Uri Shanas for sharing his knowledge of the Harderian-gland. EN would like to thank Nina Weiner and ISEF foundation for generous personal-funding. Special thanks to Raymond Dwek for support and advice. Illustration by Christopher Bickel.
No funding was required supported this work.
Availability of data and materials
EN and YV wrote the article and intellectually contributed to develop the hypothesis. EN and YV read and approve the manuscript for publication.
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The authors declare that they have no competing interests.
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Global warming potential
Global warming potential (GWP) is a relative measure of how much heat a greenhouse gas traps in the atmosphere. It compares the amount of heat trapped by a certain mass of the gas in question to the amount of heat trapped by a similar mass of carbon dioxide. A GWP is calculated over a specific time interval, commonly 20, 100, or 500 years. GWP is expressed as a factor of carbon dioxide (whose GWP is standardized to 1). In the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, methane has a lifetime of 12.4 years and with climate-carbon feedbacks a global warming potential of 86 over 20 years and 34 over 100 years in response to emissions. User related choices such as the time horizon can greatly affect the numerical values obtained for carbon dioxide equivalents. For a change in time horizon from 20 to 100 years, the GWP for methane decreases by a factor of approximately 2.5. The substances subject to restrictions under the Kyoto protocol are either rapidly increasing their concentrations in Earth's atmosphere or have a large GWP.
The GWP depends on the following factors:
- the absorption of infrared radiation by a given species
- the spectral location of its absorbing wavelengths
- the atmospheric lifetime of the species
Thus, a high GWP correlates with a large infrared absorption and a long atmospheric lifetime. The dependence of GWP on the wavelength of absorption is more complicated. Even if a gas absorbs radiation efficiently at a certain wavelength, this may not affect its GWP much if the atmosphere already absorbs most radiation at that wavelength. A gas has the most effect if it absorbs in a "window" of wavelengths where the atmosphere is fairly transparent. The dependence of GWP as a function of wavelength has been found empirically and published as a graph.
Because the GWP of a greenhouse gas depends directly on its infrared spectrum, the use of infrared spectroscopy to study greenhouse gases is centrally important in the effort to understand the impact of human activities on global climate change.
Calculating the global warming potentialEdit
Just as radiative forcing provides a simplified means of comparing the various factors that are believed to influence the climate system to one another, global warming potentials (GWPs) are one type of simplified index based upon radiative properties that can be used to estimate the potential future impacts of emissions of different gases upon the climate system in a relative sense. GWP is based on a number of factors, including the radiative efficiency (infrared-absorbing ability) of each gas relative to that of carbon dioxide, as well as the decay rate of each gas (the amount removed from the atmosphere over a given number of years) relative to that of carbon dioxide.
The radiative forcing capacity (RF) is the amount of energy per unit area, per unit time, absorbed by the greenhouse gas, that would otherwise be lost to space. It can be expressed by the formula:
where the subscript i represents an interval of 10 inverse centimeters. Absi represents the integrated infrared absorbance of the sample in that interval, and Fi represents the RF for that interval.[verification needed]
The Intergovernmental Panel on Climate Change (IPCC) provides the generally accepted values for GWP, which changed slightly between 1996 and 2001. An exact definition of how GWP is calculated is to be found in the IPCC's 2001 Third Assessment Report. The GWP is defined as the ratio of the time-integrated radiative forcing from the instantaneous release of 1 kg of a trace substance relative to that of 1 kg of a reference gas:
where TH is the time horizon over which the calculation is considered; ax is the radiative efficiency due to a unit increase in atmospheric abundance of the substance (i.e., Wm−2 kg−1) and [x(t)] is the time-dependent decay in abundance of the substance following an instantaneous release of it at time t=0. The denominator contains the corresponding quantities for the reference gas (i.e. CO2). The radiative efficiencies ax and ar are not necessarily constant over time. While the absorption of infrared radiation by many greenhouse gases varies linearly with their abundance, a few important ones display non-linear behaviour for current and likely future abundances (e.g., CO2, CH4, and N2O). For those gases, the relative radiative forcing will depend upon abundance and hence upon the future scenario adopted.
Since all GWP calculations are a comparison to CO2 which is non-linear, all GWP values are affected. Assuming otherwise as is done above will lead to lower GWPs for other gases than a more detailed approach would. Clarifying this, while increasing CO2 has less and less effect on radiative absorption as ppm concentrations rise, more powerful greenhouse gases like methane and nitrous oxide have different thermal absorption frequencies to CO2 that are not filled up (saturated) as much as CO2, so rising ppms of these gases are far more significant.
Use in Kyoto ProtocolEdit
Under the Kyoto Protocol, the Conference of the Parties decided (decision 2/CP.3) that the values of GWP calculated for the IPCC Second Assessment Report are to be used for converting the various greenhouse gas emissions into comparable CO2 equivalents when computing overall sources and sinks.
Global Temperature change Potential (GTP)Edit
The Global Temperature change Potential is another way to quantify the ratio change from a substance relative to that of CO2, in global mean surface temperature, used for a specific time span.
Importance of time horizonEdit
A substance's GWP depends on the timespan over which the potential is calculated. A gas which is quickly removed from the atmosphere may initially have a large effect, but for longer time periods, as it has been removed, it becomes less important. Thus methane has a potential of 34 over 100 years but 86 over 20 years; conversely sulfur hexafluoride has a GWP of 22,800 over 100 years but 16,300 over 20 years (IPCC Third Assessment Report). The GWP value depends on how the gas concentration decays over time in the atmosphere. This is often not precisely known and hence the values should not be considered exact. For this reason when quoting a GWP it is important to give a reference to the calculation.
The GWP for a mixture of gases can be obtained from the mass-fraction-weighted average of the GWPs of the individual gases.
Commonly, a time horizon of 100 years is used by regulators (e.g., the California Air Resources Board).
Carbon dioxide has a GWP of exactly 1 (since it is the baseline unit to which all other greenhouse gases are compared).
|GWP values and lifetimes from 2013 IPCC AR5 p714
(with climate-carbon feedbacks)
|Nitrous oxide (N2O)||121.0||268||298|
|Carbon tetrafluoride (CF4)||50000||4950||7350|
|GWP values and lifetimes from 2007 IPCC AR4 p212
(2001 IPCC TAR in parentheses)
|Lifetime in years||GWP|
|Methane||12 (12)||72 (62)||25 (23)||7.6 (7)|
|Nitrous oxide||114 (114)||289 (275)||298 (296)||153 (156)|
|HFC-23 (hydrofluorocarbon)||270 (260)||12,000 (9400)||14,800 (12,000)||12,200 (10,000)|
|HFC-134a (hydrofluorocarbon)||14 (13.8)||3,830 (3,300)||1,430 (1,300)||435 (400)|
|Sulfur hexafluoride||3200 (3,200)||16,300 (15,100)||22,800 (22,200)||32,600 (32,400)|
The values given in the table assume the same mass of compound is released; different ratios will result from the conversion of one substance to another. For instance, burning methane to carbon dioxide would reduce the global warming impact, but by a smaller factor than 25:1 because the mass of methane burned is less than the mass of carbon dioxide released (ratio 1:2.74). If you started with 1 tonne of methane which has a GWP of 25, after combustion you would have 2.74 tonnes of CO2, each tonne of which has a GWP of 1. This is a net reduction of 22.26 tonnes of GWP, reducing the global warming effect by a ratio of 25:2.74 (approximately 9 times).
The global warming potential of perfluorotributylamine (PFTBA) over a 100-year time horizon has been estimated to be approximately 7100. It has been used by the electrical industry since the mid-20th century for electronic testing and as a heat transfer agent. PFTBA has the highest radiative efficiency (relative effectiveness of greenhouse gases to restrict long-wave radiation from escaping back into space) of any molecule detected in the atmosphere to date. The researchers found an average of 0.18 parts per trillion of PFTBA in Toronto air samples, whereas carbon dioxide exists around 400 parts per million.
Water vapour has a profound infrared absorption spectrum with more and broader absorption bands than CO2, and also absorbs non-zero amounts of radiation in its low absorbing spectral regions, (see greenhouse gas (GHG)), its GWP is therefore difficult to calculate. Further, its concentration in the atmosphere depends on air temperature and water availability; using a global average temperature of ~16 °C, for example, creates an average humidity of ~18,000ppm at sea level (CO2 is ~400ppm and so concentrations of [H2O]/[CO2] ~ 45x). Another issue with calculating GWP is that, unlike other GHG, water vapor does not decay in the environment, so an average over some time period or some other measure consistent with "time dependent decay," q.v., above, must be used in lieu of the time dependent decay of artificial or excess CO2, molecules. Other factors complicating its calculation are the Earth's temperature distribution, and the differing land masses in the Northern and Southern hemispheres.
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An index used to compare the relative radiative forcing of different gases without directly calculating the changes in atmospheric concentrations. GWPs are calculated as the ratio of the radiative forcing that would result from the emission of one kilogram of a greenhouse gas to that from the emission of one kilogram of carbon dioxide over a fixed period of time, such as 100 years.
- Conference of the Parties (25 March 1998). "Methodological issues related to the Kyoto Protocol". Report of the Conference of the Parties on its third session, held at Kyoto from 1 to 11 December 1997 Addendum Part Two: Action taken by the Conference of the Parties at its third session (PDF). UNFCCC. Retrieved 17 January 2011.
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- Regulation (EU) No 517/2014 of the European Parliament and of the Council of 16 April 2014 on fluorinated greenhouse gases Annex IV.
- Myhre, G., D. Shindell, F.-M. Bréon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch, J.-F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, G. Stephens, T. Takemura and H. Zhang (2013) "Anthropogenic and Natural Radiative Forcing". In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Anthropogenic and Natural Radiative Forcing
- Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood, J. Lean, D.C. Lowe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Dorland (2007) "Changes in Atmospheric Constituents and in Radiative Forcing". In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
- "6.12.2 Direct GWPs" Archived 2007-03-29 at the Wayback Machine. in IPCC Third Assessment Report – Climate Change 2001. GRID-Arendal (2003)
- This is so, because of the reaction formula: CH4 + 2O2 → CO2 + 2 H2O. As mentioned in the article, the oxygen and water is not considered for GWP purposes, and one molecule of methane (molar mass = 16.04 g mol−1) will yield one molecule of carbon dioxide (molar mass = 44.01 g mol−1). This gives a mass ratio of 2.74. (44.01/16.04≈2.74).
- Hong, Angela C.; Cora J. Young; Michael D. Hurley; Timothy J. Wallington; Scott A. Mabury (28 November 2013). "Perfluorotributylamine: A novel long-lived greenhouse gas". Geophysical Research Letters. 40 (22): 6010–6015. Bibcode:2013GeoRL..40.6010H. doi:10.1002/2013GL058010.
- New Greenhouse Gas Discovered, PFTBA Has Higher Global Warming Impact Than CO2. Ibtimes.com (2013-12-10). Retrieved on 2014-04-23.
- Radiative efficiency definition of Radiative efficiency in the Free Online Encyclopedia. Encyclopedia2.thefreedictionary.com. Retrieved on 2014-04-23.
- Newly discovered greenhouse gas '7,000 times more powerful than CO2' | Environment. theguardian.com. 10 December 2013.
- New greenhouse gas discovered by U of T chemists | Toronto Star. Thestar.com (2013-12-11). Retrieved on 2014-04-23.
- These are normalized absorbance spectrum; these must be compensated for using the Beer–Lambert law for atmospheric concentrations, http://www.chem.arizona.edu/chemt/C21/sim/gh/ this plot provides a resultant application: Sunlight#Composition and power
- Carbon dioxide#In the Earth's atmosphere
- 2007 IPCC Fourth Assessment Report (AR4) by Working Group 1 (WG1) and Chapter 2 of that report (Changes in Atmospheric Constituents and in Radiative Forcing) which contains GWP information.
- 2001 IPCC Third Assessment Report (TAR) page on Global-Warming Potentials and Direct GWP.
- List of Global Warming Potentials and Atmospheric Lifetimes from the U.S. EPA
- An overview of the role of H2O as a greenhouse gas from RealClimate
- GWP and the different meanings of CO2e explained | <urn:uuid:c9d2cab6-9580-417e-8433-15a31612fc1b> | 3.921875 | 3,571 | Knowledge Article | Science & Tech. | 59.121622 | 95,516,549 |
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The animation presents the largest mountains, plains, rivers, lakes and deserts of the Earth.
A lightning is a sudden electrostatic discharge accompanied by a sound known as thunder.
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Physical properties, as well as the flora and fauna of the ocean change with depth. | <urn:uuid:6d9aef27-285b-444c-9c9e-cae5aacc8394> | 3.03125 | 155 | Truncated | Science & Tech. | 52.76983 | 95,516,602 |
Tuesday, January 03, 2012
"Evaporating blackholes" sounds like an apt metaphor for the economy to me...
Artist's illustration of loop quantum gravity.
(PhysOrg.com) -- As a quantum theory of gravity, loop quantum gravity could potentially solve one of the biggest problems in physics: reconciling general relativity and quantum mechanics. But like all tentative theories of quantum gravity, loop quantum gravity has never been experimentally tested. Now in a new study, scientists have found that, when black holes evaporate, the radiation they emit could potentially reveal “footprints” of loop quantum gravity, distinct from the usual Hawking radiation that black holes are expected to emit.
In this way, evaporating black holes could enable the first ever experimental test for any theory of quantum gravity. However, the proposed test would not be easy, since scientists have not yet been able to detect any kind of radiation from an evaporating black hole.
The scientists, from institutions in France and the US, have published their study called “Probing Loop Quantum Gravity with Evaporating Black Holes” in a recent issue of Physical Review Letters.
“For decades, Planck-scale physics has been thought to be untestable,” coauthor Aurélien Barrau of the French National Institute of Nuclear and Particle Physics (IN2P3) told PhysOrg.com. “Nowadays, it seems that it might enter the realm of experimental physics! This is very exciting, especially in the appealing framework of loop quantum gravity.”
In their study, the scientists have used algorithms to show that primordial black holes are expected to reveal two distinct loop quantum gravity signatures, while larger black holes are expected to reveal one distinct signature. These signatures refer to features in the black hole’s energy spectrum, such as broad peaks at certain energy levels.
Using Monte Carlo simulations, the scientists estimated the circumstances under which they could discriminate the predicted signatures of loop quantum gravity and those of the Hawking radiation that black holes are expected to emit with or without loop quantum gravity. They found that a discrimination is possible as long as there are enough black holes or a relatively small error on the energy reconstruction.
While the scientists have shown that an analysis of black hole evaporation could possibly serve as a probe for loop quantum gravity, they note that one of the biggest challenges will be simply detecting evaporating black holes.
“We should be honest: this detection will be difficult,” Barrau said. “But it is far from being impossible.”
He added that black holes are not the only possible probe of loop quantum gravity, and he’s currently investigating whether loop quantum gravity might have signatures in the universe’s background radiation.
“I am now working on the cosmological side of loop quantum gravity,” Barrau said. “This is the other way to try to test the theory: some specific footprints in the cosmic microwave background might be detected in the future.”
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New generation of catalysts demonstrated for selective hydrogenation of butadiene
A new generation of platinum-copper catalysts that require very low concentrations of platinum in the form of individual atoms to cleanly and cheaply perform important chemical reactions is reported today by Tufts University researchers in the journal Nature Communications.
Platinum is used as a catalyst in fuel cells, in automobile converters and in the chemical industry because of its remarkable ability to facilitate a wide range of chemical reactions. However, its future potential uses are significantly limited by scarcity and cost, as well as the fact that platinum readily binds with carbon monoxide, which "poisons" the desired reactions, for example in polymer electrolyte membrane (PEM) fuel cells, which are the leading contenders for small-scale and mobile power generation not based on batteries or combustion engines.
The Tufts researchers discovered that dispersing individual, isolated platinum atoms in much less costly copper surfaces can create a highly effective and cost-efficient catalyst for the selective hydrogenation of 1,3 butadiene, a chemical produced by steam cracking of naphtha or by catalytic cracking of gas oil. Butadiene is an impurity in propene streams that must be removed from the stream through hydrogenation in order to facilitate downstream polymer production. The current industrial catalyst for butadiene hydrogenation uses palladium and silver.
Like Sugar in Coffee
Copper, while a relatively cheap metal, is not nearly as catalytically powerful as platinum, noted Professor of Chemistry Charles Sykes, Ph.D., one of the senior authors on the paper. "We wanted to find a way to improve its performance."
The researchers first conducted surface science experiments to study precisely how platinum and copper metals mix. "We were excited to find that the platinum metal dissolved in copper, just like sugar in hot coffee, all the way down to single atoms. We call such materials single atom alloys," said Sykes.
The Tufts chemists used a specialized low temperature scanning tunneling microscope to visualize the single platinum atoms and their interaction with hydrogen. "We found that even at temperatures as low as minus 300 degrees F these platinum atoms were capable of splitting hydrogen molecules into atoms, indicating that the platinum atoms would be very good at activating hydrogen for a chemical reaction," Sykes said.
With that knowledge, Sykes and his fellow chemists turned to long-time Tufts collaborator Maria Flytzani-Stephanopoulos, Ph.D., the Robert and Marcy Haber Endowed Professor in Energy Sustainability at the School of Engineering, to determine which hydrogenation reaction would be most significant for industrial applications. The answer, she said, was butadiene.
The model catalyst performed effectively for that reaction in vacuum conditions in the laboratory, so Flytzani-Stephanopoulos's team took the study to the next level. They synthesized small quantities of realistic catalysts, such as platinum-copper single atom alloy nanoparticles supported on an alumina substrate, and then tested them under industrial pressure and temperatures.
"To our delight, these catalysts worked very well and their performance was steady for many days," said Flytzani-Stephanopoulos. "While we had previously shown that palladium would do related reactions in a closed reactor system, this work with platinum is our first demonstration of operation in a flow reactor at industrially relevant conditions. We believe this approach is also applicable to other precious metals if added as minority components in copper."
Further, the researchers found that the reaction actually became less efficient when they used more platinum, because clusters of platinum atoms have inferior selectivity compared with individual atoms. "In this case, less is more," said Flytzani-Stephanopoulos, "which is a very good thing."
Because platinum is at the center of many clean energy and green chemicals production technologies, such as fuel cells, catalytic converters, and value-added chemicals from bio-renewable feedstocks, the new, less expensive platinum-copper catalysts could facilitate broader adoption of such environmentally friendly devices and processes, she added.
The work is the latest fruit from a long cross-disciplinary partnership between Sykes and Flytzani-Stephanopoulos.
"Maria and I met more than seven years ago and talked regularly about how to combine our fairly different fields of research into an effective collaboration across the schools of Arts and Sciences and Engineering," said Sykes. "I had a state-of-the-art microscope that could see and manipulate atoms and molecules, and I wanted to use its unique capabilities to gain insight into industrially important chemical reactions. In the early 2000s, Maria's group had pioneered the single-atom approach for metals anchored on oxide supports as the exclusive active sites for the water-gas shift reaction to upgrade hydrogen streams for fuel cell use. Catalyst design know-how already existed in her lab. In retrospect, it seems obvious that combining forces would be a 'natural' development. Together we embarked on a new direction involving single atom alloys as catalysts for selective hydrogenation reactions. Our microscope was uniquely suited for characterizing the atomic composition of surfaces. We got funding from the National Science Foundation, U.S. Department of Energy and the Tufts Collaborates initiative to pursue this new area of research."
Sykes and Flytzani-Stephanopoulos have used this approach to design a variety of single atom alloy catalysts that have, in the last two years, sparked international interest.
"Traditionally catalyst development happens by trial and error and screening many materials," said Flytzani-Stephanopoulos. "In this study we took a fundamental approach to understanding the atomic scale structure and properties of single atom alloy surfaces and then applied this knowledge to develop a working catalyst. Armed with this knowledge, we are now ready to compare the stability of these single atom alloy catalysts to single atom catalysts supported on various oxide or carbon surfaces. This may give us very useful criteria for industrial catalyst design."
The research was primarily performed by co-authors Felicia R. Lucci and Jilei Liu, senior graduate students in the Sykes and Stephanopoulos labs, respectively. Other authors on the paper are doctoral students Matthew D. Marcinkowski (chemistry) and Ming Yang (chemical engineering), and Lawrence F. Allard, Ph.D., of the Materials Science & Technology Division, Oak Ridge National Laboratory, who led the state of the art imaging of the catalytic samples.
Funding for this work came from the Department of Energy, grant DE-FG02-05ER15730, and the National Science Foundation, grant CBET-1159882.
"Selective hydrogenation of butadiene on platinum copper alloys at the single atom limit," Nature Communications, DOI: 10.1038/NCOMMS9550.
Tufts University, located on three Massachusetts campuses in Boston, Medford/Somerville and Grafton, and in Talloires, France, is recognized among the premier research universities in the United States. Tufts enjoy a global reputation for academic excellence and for the preparation of students as leaders in a wide range of professions. A growing number of innovative teaching and research initiatives span all Tufts campuses, and collaboration among the faculty and students in the undergraduate, graduate and professional programs across the university's schools is widely encouraged.
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Crab Nebula(redirected from Messier Object 1)
Also found in: Dictionary, Thesaurus.
Crab Nebula,diffuse gaseous nebulanebula
[Lat.,=mist], in astronomy, observed manifestation of a collection of highly rarefied gas and dust in interstellar space. Prior to the 1960s this term was also applied to bodies later discovered to be galaxies, e.g.
..... Click the link for more information. in the constellation Taurus; cataloged as NGC 1952 and M1, the first object recorded in Charles Messier's catalog of nonstellar objects (see Messier catalogMessier catalog
, systematic list of nebulae and star clusters. A first list, compiled and published in 1771 by Charles Messier, contained 45 objects. The final list, published in 1784, contained 103 objects; some of these were later removed from the list.
..... Click the link for more information. ). It is the remnant of a supernovasupernova,
a massive star in the latter stages of stellar evolution that suddenly contracts and then explodes, increasing its energy output as much as a billionfold. Supernovas are the principal distributors of heavy elements throughout the universe; all elements heavier than
..... Click the link for more information. that was observed in 1054 by Chinese and Arab astronomers to be as bright as Venus; markings in northern New Mexico depict a star near a crescent moon that might be a record of this supernova. Only three other supernovas have been observed in our galaxy since then. The explosion of the Crab Nebula produced a large expanding shell of delicate filaments. The filaments contain ionized gas in which unusually energetic electrons twist through magnetic fields at speeds close to that of light, emitting synchrotron radiation. Although this radiation is what makes supernova remnants visible in radio wavelengths, in this nebula it is so strong that observers can see the filaments through moderate-sized optical telescopes under good conditions. The nebula is also a strong emitter of X rays. At its center is a pulsarpulsar,
in astronomy, a neutron star that emits brief, sharp pulses of energy instead of the steady radiation associated with other natural sources. The study of pulsars began when Antony Hewish and his students at Cambridge built a primitive radio telescope to study a
..... Click the link for more information. , PSR 0531+21, that spins 30 times per second. The youngest pulsar observed, it gives off radiation at radio, optical, ultraviolet, X-ray, and gamma ray wavelengths, as well as electrons that power the synchrotron radiation in the surrounding nebula.
Crab nebula(Ml; NGC 1952) A turbulent expanding mass of gas and dust with luminous twisting filaments of ionized gas, lying about 2000 parsecs away and located in the sky near the star Zeta (ζ) Tauri in the constellation Taurus. It is a supernova remnant, the result of a supernova (probably of type II) that was almost certainly observed by Chinese and Japanese astronomers in 1054 and was sufficiently bright (magnitude about –5) to be visible in daylight for more than three weeks. At present it is about four parsecs in diameter. The Crab nebula emits synchrotron radiation of all wavelengths and is a particularly strong source of X-rays (Taurus X-1) and radio waves (Taurus A). It was named the Crab nebula in 1848 by its first modern observer, the Irish astronomer William Parsons, 3rd Earl of Rosse (1800–67).
The star whose explosion produced the Crab nebula is now a young optical pulsar (the Crab pulsar NP 0532), identified as such in 1967. Its pulsations are also observed at radio, infrared, X-ray, and gamma-ray wavelengths. These pulsations have a period of only 0.0331 seconds. The pulsar is the power house for the Crab nebula: energy is being lost by the pulsar in the form of highly energetic electrons, causing the pulsar to slow down very gradually; the electrons interact with the intense magnetic field extending into the nebula and radiate synchrotron emission. The energy loss of the pulsar equals the total energy radiated by the nebula (1030 to 1031 J s–1). The ultraviolet component of this radiation ionizes the gas in the filaments, causing the atoms to fluoresce. The Crab nebula is the defining member of the class of filled supernova remnants, or plerions.
a galactic nebula, the result of a supernova explosion in 1054 in Taurus. The distance to the nebula is 1,700 parsecs, and its radius is about 1 parsec. It is expanding at a speed of 1,000–1,500 km/sec. The nebula has the form of an elongated ellipsoid and a filamentary structure. The total mass of gas in the Crab Nebula is about 0.1 solar mass. About 80 percent of the nebula's luminosity (it has a visual stellar magnitude of 8.5) is concentrated not in the filaments but in the amorphous mass occupying the interior of the ellipsoid.
The Crab Nebula is a source of radio emission (Taurus A). In the interval between the radio and the optical regions of the spectrum there is a noticeable maximum in the radiation, the nature of which is not yet known. In the direction of shorter wavelengths, the spectrum extends to the X-ray region; only the central part of the nebula and the star itself radiate in this region. The radiation of the amorphous mass at all wavelengths is produced by fast (relativistic) electrons (with energies of 108–1012 eV) moving in a magnetic field (of intensity 10-3 oersted, or 8 X 10-2 A/m); this is what is known as synchrotron radiation. The generation of particles and of the magnetic field is associated with the remnant of the supernova, which is a pulsar with a radius of about 10 km, rotating with a period of 0.033 sec and producing bursts of optical, X-ray, and radio radiation. The star has a magnetic field of large intensity. The rapid rotation of this field produces electromagnetic effects, resulting in the acceleration of the particles and bursts of radiation. The field itself “twists” and then expands into the nebula. The pressure of the field and the particles accelerates the expansion of the nebula.
The study of the Crab Nebula, a unique celestial object, has made it possible to solve a number of problems of stellar evolution connected with the origin of pulsars.
S. B. PIKEL'NER | <urn:uuid:fc219ae3-e151-4dd8-be23-a15d630b0c60> | 3.0625 | 1,410 | Structured Data | Science & Tech. | 52.679341 | 95,516,630 |
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How to build your own magic squares.
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Jo has three numbers which she adds together in pairs. When she does this she has three different totals: 11, 17 and 22 What are the three numbers Jo had to start with?”
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The diagram shows a 5 by 5 geoboard with 25 pins set out in a square array. Squares are made by stretching rubber bands round specific pins. What is the total number of squares that can be made on a. . . . | <urn:uuid:4c9f177c-1136-4d0b-bbeb-d69182c8f1bd> | 3.78125 | 1,438 | Content Listing | Science & Tech. | 89.885475 | 95,516,661 |
|Standard atomic weight (Ar, standard)||22(2)168.934|
|Thulium in the periodic table|
|Atomic number (Z)||69|
|Electron configuration||[Xe] 4f13 6s2|
Electrons per shell
|2, 8, 18, 31, 8, 2|
|Phase at STP||solid|
|Melting point||1818 K (1545 °C, 2813 °F)|
|Boiling point||2223 K (1950 °C, 3542 °F)|
|Density (near r.t.)||9.32 g/cm3|
|when liquid (at m.p.)||8.56 g/cm3|
|Heat of fusion||16.84 kJ/mol|
|Heat of vaporization||191 kJ/mol|
|Molar heat capacity||27.03 J/(mol·K)|
2, 3 |
|Electronegativity||Pauling scale: 1.25|
|Atomic radius||empirical: 176 pm|
|Covalent radius||190±10 pm|
|Crystal structure||hexagonal close-packed (hcp)|
|Thermal expansion||poly: 13.3 µm/(m·K) (at r.t.)|
|Thermal conductivity||16.9 W/(m·K)|
|Electrical resistivity||poly: 676 nΩ·m (at r.t.)|
|Magnetic ordering||paramagnetic (at 300 K)|
|Magnetic susceptibility||+25,500·10−6 cm3/mol (291 K)|
|Young's modulus||74.0 GPa|
|Shear modulus||30.5 GPa|
|Bulk modulus||44.5 GPa|
|Vickers hardness||470–650 MPa|
|Brinell hardness||470–900 MPa|
|Naming||after Thule, a mythical region in Scandinavia|
|Discovery and first isolation||Per Teodor Cleve (1879)|
|Main isotopes of thulium|
Thulium is a chemical element with symbol Tm and atomic number 69. It is the thirteenth and third-last element in the lanthanide series. Like the other lanthanides, the most common oxidation state is +3, seen in its oxide, halides and other compounds; because it occurs so late in the series, however, the +2 oxidation state is also stabilized by the nearly full 4f shell that results. In aqueous solution, like compounds of other late lanthanides, soluble thulium compounds form coordination complexes with nine water molecules.
In 1879, the Swedish chemist Per Teodor Cleve separated from the rare earth oxide erbia another two previously unknown components, which he called holmia and thulia; these were the oxides of holmium and thulium, respectively. A relatively pure sample of thulium metal was first obtained in 1911.
Thulium is the second-least abundant of the lanthanides, after radioactively unstable promethium which is only found in trace quantities on Earth. It is an easily workable metal with a bright silvery-gray luster. It is fairly soft and slowly tarnishes in air. Despite its high price and rarity, thulium is used as the radiation source in portable X-ray devices, and in some solid-state lasers. It has no significant biological role and is not particularly toxic.
Pure thulium metal has a bright, silvery luster, which tarnishes on exposure to air. The metal can be cut with a knife, as it has a Mohs hardness of 2 to 3; it is malleable and ductile. Thulium is ferromagnetic below 32 K, antiferromagnetic between 32 and 56 K, and paramagnetic above 56 K.
- 4 Tm + 3 O2 → 2 Tm2O3
Thulium is quite electropositive and reacts slowly with cold water and quite quickly with hot water to form thulium hydroxide:
- 2 Tm (s) + 6 H2O (l) → 2 Tm(OH)3 (aq) + 3 H2 (g)
Thulium reacts with all the halogens. Reactions are slow at room temperature, but are vigorous above 200 °C:
- 2 Tm (s) + 3 F2 (g) → 2 TmF3 (s) (white)
- 2 Tm (s) + 3 Cl2 (g) → 2 TmCl3 (s) (yellow)
- 2 Tm (s) + 3 Br2 (g) → 2 TmBr3 (s) (white)
- 2 Tm (s) + 3 I2 (g) → 2 TmI3 (s) (yellow)
- 2 Tm (s) + 3 H2SO4 (aq) → 2 Tm3+ (aq) + 3 SO2−
4 (aq) + 3 H2 (g)
Thulium reacts with various metallic and non-metallic elements forming a range of binary compounds, including TmN, TmS, TmC2, Tm2C3, TmH2, TmH3, TmSi2, TmGe3, TmB4, TmB6 and TmB12. In those compounds, thulium exhibits valence states +2 and +3, however, the +3 state is most common and only this state has been observed in thulium solutions. Thulium exists as a Tm3+ ion in solution. In this state, the thulium ion is surrounded by nine molecules of water. Tm3+ ions exhibit a bright blue luminescence.
Thulium's only known oxide is Tm2O3. This oxide is sometimes called "thulia". Reddish-purple thulium(II) compounds can be made by the reduction of thulium(III) compounds. Examples of thulium(II) compounds include the halides (except the fluoride). Some hydrated thulium compounds, such as TmCl3·7H2O and Tm2(C2O4)3·6H2O are green or greenish-white. Thulium dichloride reacts very vigorously with water. This reaction results in hydrogen gas and Tm(OH)3 exhibiting a fading reddish color. Combination of thulium and chalcogens results in thulium chalcogenides.
The isotopes of thulium range from 145Tm to 179Tm. The primary decay mode before the most abundant stable isotope, 169Tm, is electron capture, and the primary mode after is beta emission. The primary decay products before 169Tm are element 68 (erbium) isotopes, and the primary products after are element 70 (ytterbium) isotopes.
Thulium-169 is thulium's longest-lived and most abundant isotope. It is the only isotope of thulium that is thought to be stable, although it is predicted to undergo alpha decay to holmium-165 with a very long half-life. After thulium-169, the next-longest-lived isotopes are thulium-171, which has a half-life of 1.92 years, and thulium-170, which has a half-life of 128.6 days. Most other isotopes have half-lives of a few minutes or less. Thirty-five isotopes and 26 nuclear isomers of thulium have been detected. Most isotopes of thulium lighter than 169 atomic mass units decay via electron capture or beta-plus decay, although some exhibit significant alpha decay or proton emission. Heavier isotopes undergo beta-minus decay.
Thulium was discovered by Swedish chemist Per Teodor Cleve in 1879 by looking for impurities in the oxides of other rare earth elements (this was the same method Carl Gustaf Mosander earlier used to discover some other rare earth elements). Cleve started by removing all of the known contaminants of erbia (Er2O3). Upon additional processing, he obtained two new substances; one brown and one green. The brown substance was the oxide of the element holmium and was named holmia by Cleve, and the green substance was the oxide of an unknown element. Cleve named the oxide thulia and its element thulium after Thule, an Ancient Greek place name associated with Scandinavia or Iceland. Thulium's atomic symbol was once Tu, but this was changed to Tm.
Thulium was so rare that none of the early workers had enough of it to purify sufficiently to actually see the green color; they had to be content with spectroscopically observing the strengthening of the two characteristic absorption bands, as erbium was progressively removed. The first researcher to obtain nearly pure thulium was Charles James, a British expatriate working on a large scale at New Hampshire College in Durham. In 1911 he reported his results, having used his discovered method of bromate fractional crystallization to do the purification. He famously needed 15,000 purification operations to establish that the material was homogeneous.
High-purity thulium oxide was first offered commercially in the late 1950s, as a result of the adoption of ion-exchange separation technology. Lindsay Chemical Division of American Potash & Chemical Corporation offered it in grades of 99% and 99.9% purity. The price per kilogram has oscillated between US$4,600 and $13,300 in the period from 1959 to 1998 for 99.9% purity, and it was second highest for lanthanides behind lutetium.
The element is never found in nature in pure form, but it is found in small quantities in minerals with other rare earths. Thulium is often found with minerals containing yttrium and gadolinium. In particular, thulium occurs in the mineral gadolinite. However, thulium also occurs in the minerals monazite, xenotime, and euxenite. Thulium has not been found in prevalence over the other rare earths in any mineral yet. Its abundance in the Earth's crust is 0.5 mg/kg by weight and 50 parts per billion by moles. Thulium makes up approximately 0.5 parts per million of soil, although this value can range from 0.4 to 0.8 parts per million. Thulium makes up 250 parts per quadrillion of seawater. In the solar system, thulium exists in concentrations of 200 parts per trillion by weight and 1 part per trillion by moles. Thulium ore occurs most commonly in China. However, Australia, Brazil, Greenland, India, Tanzania, and the United States also have large reserves of thulium. Total reserves of thulium are approximately 100,000 tonnes. Thulium is the least abundant lanthanide on earth except for promethium.
Thulium is principally extracted from monazite ores (~0.007% thulium) found in river sands, through ion-exchange. Newer ion-exchange and solvent-extraction techniques have led to easier separation of the rare earths, which has yielded much lower costs for thulium production. The principal sources today are the ion adsorption clays of southern China. In these, where about two-thirds of the total rare-earth content is yttrium, thulium is about 0.5% (or about tied with lutetium for rarity). The metal can be isolated through reduction of its oxide with lanthanum metal or by calcium reduction in a closed container. None of thulium's natural compounds are commercially important. Approximately 50 tonnes per year of thulium oxide are produced. In 1996, thulium oxide cost US$20 per gram, and in 2005, 99%-pure thulium metal powder cost US$70 per gram.
Thulium has a few applications:
Holmium-chromium-thulium triple-doped yttrium aluminum garnet (Ho:Cr:Tm:YAG, or Ho,Cr,Tm:YAG) is an active laser medium material with high efficiency. It lases at 2080 nm and is widely used in military applications, medicine, and meteorology. Single-element thulium-doped YAG (Tm:YAG) lasers operate at 2,01 μm. The wavelength of thulium-based lasers is very efficient for superficial ablation of tissue, with minimal coagulation depth in air or in water. This makes thulium lasers attractive for laser-based surgery.
Despite its high cost, portable X-ray devices use thulium that has been bombarded in a nuclear reactor as a radiation source. These sources have a useful life of about one year, as tools in medical and dental diagnosis, as well as to detect defects in inaccessible mechanical and electronic components. Such sources do not need extensive radiation protection – only a small cup of lead.
Thulium-170 is gaining popularity as an X-ray source for cancer treatment via brachytherapy. This isotope has a half-life of 128.6 days and five major emission lines of comparable intensity (at 7.4, 51.354, 52.389, 59.4 and 84.253 keV). Thulium-170 is one of the four most popular radioisotopes for use in industrial radiography.
Thulium has been used in high-temperature superconductors similarly to yttrium. Thulium potentially has use in ferrites, ceramic magnetic materials that are used in microwave equipment. Thulium is also similar to scandium in that it is used in arc lighting for its unusual spectrum, in this case, its green emission lines, which are not covered by other elements. Because thulium fluoresces with a blue color when exposed to ultraviolet light, thulium is put into euro banknotes as a measure against counterfeiting. The blue fluorescence of Tm-doped calcium sulfate has been used in personal dosimeters for visual monitoring of radiation. Tm-doped halides which Tm is in its 2+ valence state, are promising luminescent materials that can make efficient electricity generating windows based on the principle of a luminescent solar concentrator, possible .
Biological role and precautionsEdit
Soluble thulium salts are mildly toxic, but insoluble thulium salts are completely nontoxic. When injected, thulium can cause degeneration of the liver and spleen and can also cause hemoglobin concentration to fluctuate. Liver damage from thulium is more prevalent in male mice than female mice. Despite this, thulium has a low level of toxicity. In humans, thulium occurs in the highest amounts in the liver, kidneys and bones. Humans typically consume several micrograms of thulium per year. The roots of plants do not take up thulium, and the dry weight of vegetables usually contains one part per billion of thulium. Thulium dust and powder are toxic upon inhalation or ingestion and can cause explosions. Radioactive thulium isotopes can cause radiation poisoning.
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- DOI: 10.1016/j.solmat.2015.04.002
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|Look up thulium in Wiktionary, the free dictionary.|
- Poole, Charles P., Jr. (2004). Encyclopedic Dictionary of Condensed Matter Physics. Academic Press. p. 1395. ISBN 978-0-08-054523-3. | <urn:uuid:25e1eded-1ab2-414b-a707-93bd9d828a53> | 2.71875 | 4,777 | Knowledge Article | Science & Tech. | 68.941643 | 95,516,676 |
STELLAR POPULATIONS IN BULGES OF SPIRAL GALAXIES
To better understand bulge formation, we have used long-slit spectroscopy and imaging to obtain luminosity-weighted (SSP) ages and abundances, line of sight velocity distributions, and bulge-to-disk decomposition for 38 spiral galaxies. We specifically included several blue bulges to see if these show evidence for secular evolution. Here we describe the stellar populations and how they relate to the kinematics and dynamics. We find that red bulges are similar to luminous ellipticals in their central line strengths, with large SSP ages and super-solar metallicities and α/Fe ratios. Blue bulges are similar to low-luminosity ellipti-cals in their central line strengths. They have solar α/Fe ratios and either small age or small metallicity. The colors, metallicities, and α/Fe ratios of bulges are correlated with the central velocity dispersion and maximum disk rotational velocity. Most bulges have metallicity gradients, but the metallicities of the bulge and disk are correlated. These observations suggest that the star-formation histories of ellipticals, bulges, and disks are sensitive primarily to the depth of the galactic potential well, but the scatter in the scaling relations leaves room for multiple formation mechanisms.
KeywordsSpiral Galaxy Stellar Population Secular Evolution Maximum Disk Lenticular Galaxy
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The effect of radioactive waste storage in Andreev Bay on contamination of the Barents Sea ecosystem
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The effect of temporary radioactive waste storage on the ecological status of the sea and biota in the littoral of Andreev and Malaya Andreev bays and near the shore of Motovskii Gulf (including the mouth part of the Zapadnaya Litsa Bay) was analyzed. The littoral sediments contaminated by the 137Сs, 90Sr, 238Pu, and 239,240Pu isotopes are located in the zones of constant groundwater discharge on the shores of Andreev and Malaya Andreev bays. The littoral slopes and bottom depressions of the bays accumulate finely dispersed terrigenous material and 137Сs. The investigations have shown that the storage does not exert a significant adverse effect on the radioactive conditions and the status of the sea ecosystems beyond Andreev Bay.
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- 1.A. P. Vasil’ev, V. P. Vyasyukhno, M. E. Netecha, et al., At. Energ. 101 (1), 49–55 (2006).Google Scholar
- 5.G. V. Ilyin, I. S. Usyagina, and N. E. Kasatkina, At. Energ. 118 (3), 168–173 (2015).Google Scholar
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Debates aberrant species, e.g., Ornithorhynchus and Echidna, with Hooker. Darwin argues they are result of extinction having removed intermediate links to allied forms. Studying effects of disuse in wings of tame and wild ducks. Tabulations showing that number of species in a genus is not correlated with number of genera in an order.
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The biologists assessed data on the composition and species numbers of plants on the summits of seven mountains measuring over 3000 metres in the Bernina range in Switzerland over a period of almost one hundred years. They noticed that as a result of climate change, an upward shift of flora is taking place.
This is increasing the number of species on the mountain summits studied, but also leading to an increasing homogenization of the species composition of Alpine summit vegetation. This means that species diversity within individual areas (‘alpha diversity’) is increasing, but that species diversity across ecosystems (‘beta diversity’) is declining.
Seen generally, biodiversity can decline for two main reasons: through the disappearance of species, or when specialised species are replaced by generalists. The resulting homogenization can lead to a reduction in regional biodiversity. Until now, the question of homogenization has, however, primarily been discussed in connection with the impacts of invasive species, and less in the context of climate change. The evaluation of the data from the Bernina range now puts this debate in a new light.
For their study, the two researchers analysed data from their colleague Gian-Reto Walther, who investigated the top ten metres of these summits in detail in 2003 and made notes of all the plants. They compared these records with surveys from the years 1907 and 1985. On average, the number of plant species rose from 10 to 28 species per summit. The increasing temperatures has evidently brought about a proper ‘summit meeting’. More and more species are now forced to share the summits.
At the last count in 2003, however, no species were found to have disappeared since 1907. By contrast, the differences between the summits declined significantly over the same period. Today the summits of the Minor range are not only more similar to each other, they are also more similar to the neighbouring Languard range than before, despite the fact that they are separated from each other within the Bernina Alps by the Val da Fain.
“This is a clear sign of the early stages of homogenization,” says Gerald Jurasinski, a biogeographer from the University of Bayreuth. “We suspect that the accessibility and popularity of these summits among climbers is playing a role here – after all, seeds can also be carried on people’s clothes and shoes. But unfortunately there is not yet any data for this,” remarks Jürgen Kreyling of the Helmholtz Centre for Environmental Research - UFZ. The two researchers hope their work will draw attention to the fact that biodiversity means more than species richness.
The composition of the species spectrum, beta diversity and functional diversity also play an important role in functioning ecosystems. The University of Bayreuth is carrying out intensive research into this topic in collaboration with the UFZ, and this is also reflected in its courses, e.g. the Masters degree in Global Change Ecology, which forms part of the Bavarian Elite programme.
Doris Boehme | alfa
Global study of world's beaches shows threat to protected areas
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
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Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
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A particle is located on the coordinate plane at . Define a move for the particle as a counterclockwise rotation of radians about the origin followed by a translation of units in the positive -direction. Given that the particle's position after moves is , find the greatest integer less than or equal to .
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Dutch researcher Annelieke Franke has discovered that the aging of the brain adversely affects the fertility of female rats. The scientist suspects that her research will provide insights into fertility problems of women over the age of 30.
Franke studied relatively young subfertile rats. Although the pituitary gland and ovaries of these rats still functioned normally, their brains had already started to function differently. This led Franke to conclude that the ageing of the brain reduces fertility.
Generally speaking, human brains regulate the reproductive system in the same manner as rat brains. However, an important difference is that rats still posses a significant number of oocytes after the fertile period, whereas in humans the supply is considerably depleted. This reduced supply of oocytes is the most important limiting factor for fertility in older women.
Sonja Jacobs | alfa
Colorectal cancer risk factors decrypted
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Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
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13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:e5f00684-7cd3-4bd0-8ce0-be000390969f> | 3.046875 | 811 | Content Listing | Science & Tech. | 37.765811 | 95,516,761 |
Featured Data Nugget: You may think that blow fly maggots are gross, but did you know they can help solve crimes? The age of a maggot helps scientists determine how long ago a body died.
Featured Data Nugget: Because herbivores are so important for how plants grow, they may determine how well an exotic plant does in its new habitat and whether it becomes invasive.
Featured Data Nugget: Male and female anole lizards are very different from one another. Natural selection from predators may drive these differences.
Featured Data Nugget: The world's coral reefs are home to a large diversity of plants and animals, and are threatened by climate change. When the water gets too warm, some corals bleach and some can survive.
Featured Data Nugget: Scientists taking soil cores to determine whether organic matter stores important nutrients, like phosphorus, in wetland soils.
Featured Data Nugget: Climate change is causing waters to warm, and species will need to adapt to survive. Do salmon have the genes necessary to survive in these new conditions?
Featured Data Nugget: The Hubbard Brook Experimental Forest is home to the one of the longest running bird studies ever conducted! What can we learn about migratory bird populations from this unique long-term dataset?
Featured Data Nugget: Big wings allow butterflies to fly everywhere with ease. But you may wonder, why are the wings of some species so brightly colored?
Featured Data Nugget: People have hunted whales for over 5,000 years for their meat, oil, and blubber. Today, as populations are struggling to recover, they are faced with additional challenges due to climate change.
Featured Data Nugget: What can tree rings tell us about the past climate of Australia, and whether current weather patterns are changing due to climate change?
Featured Data Nugget: Grasshopper mice feed on two different species of scorpions - one with a painful sting and one that is painless. Will the mice choose to avoid the scorpions with the painful sting?
Featured Data Nugget: Corn is used to produce most of the biofuels that humans consume today, but it does not make a good habitat for wildlife. Can diverse prairies serve as a viable alternative?
Featured Data Nugget: Today more and more people are moving from rural to urban areas. This means that cities are becoming the primary places where many people experience nature and interact with wildlife.
Featured Data Nugget: When is a mutualism not a mutualism? Under certain environmental conditions, such as soils with high nitrogen, Rhizobia may become parasites to plants. | <urn:uuid:fa77b6a0-b947-4164-a19e-b1640af161a4> | 3.03125 | 532 | Content Listing | Science & Tech. | 38.2612 | 95,516,764 |
Identifying regions important for spreading and mediating perturbations is crucial to assess the susceptibilities of spatio-temporal complex systems such as the Earth’s climate to volcanic eruptions, extreme events or geoengineering.
Here a data-driven approach is introduced based on a dimension reduction, causal reconstruction, and novel network measures based on causal effect theory that go beyond standard complex network tools by distinguishing direct from indirect pathways. Applied to a data set of atmospheric dynamics, the method identifies several strongly uplifting regions acting as major gateways of perturbations spreading in the atmosphere.
Additionally, the method provides a stricter statistical approach to pathways of atmospheric teleconnections, yielding insights into the Pacific–Indian Ocean interaction relevant for monsoonal dynamics. Also for neuroscience or power grids, the novel causal interaction perspective provides a complementary approach to simulations or experiments for understanding the functioning of complex spatio-temporal systems with potential applications in increasing their resilience to shocks or extreme events.
Research news | 2018-07-10
The World in 2050 initiative launches new report outlining synergies and benefits that render the goals achievable
Educational news | 2018-07-02
LEAP our leadership programme designed for changemakers that want to lead social-ecological transformations to sustainability. Application deadline is 5 August 2018.
Research news | 2018-06-27
Overfishing, fractured international relationships and political conflicts loom as fish migrate more unpredictably because of climate change. Here is how to deal with it
Research news | 2018-06-26
Profit-maximizing approaches are most likely to produce outcomes that harm people or the environment. But it depends on the circumstances whether a sustainable or a safe approach is most suitable, new study argues
General news | 2018-06-20
Will lead a redesign of the organisational structure at the centre
Research news | 2018-06-20
New book chapter looks into the economic, cultural and ecological reasons why some people leave the fisheries and aquaculture sector, and what could be done to reverse the trend | <urn:uuid:2b6e1565-0149-4bc5-8128-1cc7e77d7664> | 2.65625 | 420 | Content Listing | Science & Tech. | 4.886838 | 95,516,770 |
Waves in Rotating Fluids
Gravity waves were discussed in the previous chapter. These waves are of great importance for the dynamics of the ocean and the atmosphere. No less important are waves related to the rotation of the Earth. The theory of such waves, as well as the development of the theory of gravity waves which takes the Earth’s rotation into account, is the main purpose of this chapter.
KeywordsDispersion Relation Group Velocity Gravity Wave Dispersion Curve Internal Wave
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Researchers at MIT and Lawrence Berkeley National Laboratory have developed a new type of catalyst that can be tuned to promote desired chemical reactions, potentially enabling the replacement of expensive and rare metals in fuel cells.
The new catalyst is carbon-based, made of graphite with additional compounds bonded to the edges of two-dimensional sheets of graphene that make up the material. By adjusting the composition and amounts of these added compounds, the characteristics of the catalyst can be adjusted to favor specific chemical reactions.
The new catalytic material is described in a paper published in JACS, the Journal of the American Chemical Society, by MIT assistant professor of chemistry Yogesh Surendranath and three collaborators.
Catalysts enhance the rate of a chemical reaction but are not consumed in the process. As a result, the repeated action of very small amounts of a catalyst can have large and long-lasting effects.
There are two basic types of electrocatalysts, which are crucial for enabling reactions in devices such as fuel cells or electrolyzers. Molecular electrocatalysts have the advantage of being relatively easy to tune by chemical treatment, so their reactivity and selectivity match the desired application; heterogeneous electrocatalysts, which are much more durable and easy to process into a device, tend to lack that ability for precise control.
“What we wanted to do was to figure out a way to bridge those two worlds,” Surendranath explains. His team was able to accomplish that by taking graphite and finding a way to chemically modify its surface to give it the desired tunability.
The basic material used is pure carbon, which is “the universal electrode material” in batteries and fuel cells, Surendranath says. By finding a way to make this material tunable in the same ways as molecular catalysts, the researchers are providing an opening to a new approach to the design of such materials, which are also a key part of many chemical manufacturing processes.
In addition to their possible uses in fuel cells, such new catalysts could also be useful for enhancing chemical reactions, such as reducing carbon dioxide to convert it into a usable fuel, Surendranath says. This could reduce emissions of a principal greenhouse gas that fosters climate change, and transform it into a useful, renewable fuel.
The initial finding described in this paper is “just one piece of what we believe is a large iceberg,” Surendranath adds, since the basic ingredient is “a dirt cheap material that we are modifying using well-known chemistry.”
One frequent barrier to taking systems that work in the laboratory and making them into practical, marketable products is the ability to scale up the production process. “You need to be able to scale efficiently,” Surendranath says. The fact that the basis for the new catalyst is “a class of materials that are already made at scale, for commodities like paint and rubber,” should make scaling up their process relatively straightforward, he says: “All the keys to that are already in place.”
Surendranath says that this finding is particularly exciting because chemists “usually take a very precise refined material and then engineer some of its properties. But in this case, it allows us to take a material that is cheap and abundant, and turn it into something very valuable. It’s a different paradigm.”
The research team also included postdoc Tomohiro Fukushima at MIT and Walter Drisdell and Junko Yano at Lawrence Berkeley National Laboratory in California. The work was supported, in part, by the U.S. Department of Energy. | <urn:uuid:5d3b8a95-e90f-4ea2-a8fe-e2120558e188> | 4.03125 | 749 | News Article | Science & Tech. | 24.671045 | 95,516,837 |
Large-Scale Production of Airglass
Our work with silica aerogel started in 1976, as part of the preparations made for a new experiment at the CERN Intersecting Storage Rings. The spectrometer in the experiment should have a Cerenkov counter with a radiator of refractive index 1.050. Silica aerogel is the only material with a refractive index in that range. Our first attempts to produce aerogel were made at the Chemical Centre in Lund, where we used a small two litre autoclave. Since we were going to use aerogel as a Cerenkov radiator, our first and most important concern was to improve its transparency in the blue region of the spectrum.
KeywordsPressure Vessel Pilot Plant Silica Aerogel Solar Panel Cerenkov Radiator
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Scientists use hydroacoustics to find abundance of marine life in reserve is four times greater than in surrounding waters
Researchers at Scripps Institution of Oceanography at the University of California San Diego were part of an international team that for the first time used hydroacoustics as a method for comparing the abundance of fishes within and outside marine protected areas (MPAs).
They found that the abundance of fishes was four times greater in Mexico's protected Cabo Pulmo National Park than in areas outside the park. Study authors said that hydroacoustics points the way toward a new, more cost-effective method of assessing fish populations.
"Managers and authorities in many countries spend a lot of financial resources assessing marine protected areas," said study co-author Octavio Aburto, a marine ecologist at Scripps. "The results of this paper demonstrate that it is possible to use acoustic technologies to generate information about marine resources inside MPAs in a faster and less expensive way, reducing the costs for governments in ocean conservation."
The study, "Hydroacoustics as a tool to examine the effects of Marine Protected Areas and habitat type on marine fish communities," appears Jan. 15 in the journal Scientific Reports. The National Science Foundation, the Baja Coastal Institute, the International Community Foundation, David and Lucile Packard Foundation, and The Helmsley Charitable Trust funded the research.
Cabo Pulmo has been the site of several studies by Scripps researchers since 2002. In 1995, local fishermen led the creation of a 71-square-kilometer (27-square-mile) undersea park to protect the waters they fished. The current MPA has been identified as the most successful in the world in terms of maintaining a sustainable fishery in which fleets operate just beyond the boundaries of the MPA. There, as in other parts of the world, surveys of coastal marine life are often performed through underwater visual censuses taken by scuba divers.
Researchers surveyed the waters of the MPA using sound waves produced by hydroacoustic equipment mounted on boats to image schools of fish and other marine life. They performed transects, scanning the water column in rows. They similarly surveyed waters outside the MPA. Fish density, total biomass, and the size of individuals were significantly greater inside the MPA. In comparison with waters outside the MPA, animal abundance in reefs was as much as 50 times higher, "highlighting the importance of both habitat complexity and protection from fishing for fish populations."
"Both hydroacoustics and marine protected areas are well-established but it is novel to use the former to assess the latter," said study lead author Jack Egerton, now a researcher at the University of Texas who performed the work while at Bangor University in Wales, UK. "Through this, we have been able to see how important the Cabo Pulmo National Park is for fish populations in the area."
Although acoustic surveys can be done much faster than underwater visual censuses, the researchers acknowledge that fish sizes can only be approximated and the method doesn't provide species-specific information. However, they concluded that the hydroacoustic method could still be useful in gauging the benefit of MPAs, as conventional survey methods are often prohibitively expensive and can be limited by issues such as diver depth limits and water clarity.
Study co-authors include Scripps postdoctoral scholar Andrew Johnson and researchers from Bangor University and the Centro para la Bioversidad Marina y la Conservación in La Paz, Mexico.
Rob Monroe | 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
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
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posted by adlfa
give diameter of the atomic nucleus of lead atom is 1.75x10m
It would help if you proofread your questions before you posted them. 1.75*10m = 17.5m would be relatively large.
Online, “*” is used to indicate multiplication to avoid confusion with “x” as an unknown. | <urn:uuid:adf090f8-771f-4cb6-8a18-b078c37a5649> | 2.65625 | 79 | Q&A Forum | Science & Tech. | 71.476667 | 95,516,868 |
Most riders of this amusement ride may not be aware that there is no engine for operation. Then, how does a roller coaster work? Before actually understanding the mechanism, we have to understand two words from the glossary of physics. They are potential energy and kinetic energy.
Potential energy is defined as that energy that is inherent in a physical system in juxtaposition with conservative force acting on it. On the movement of an object from its position against a force, energy is expended and a potential difference is created. Upon allowing the object to return to its original position the energy supplied is recovered.
The best example here is the thing which has elasticity. Due to the elastic potential energy, elastic materials regain their original position. There are different types of potential energies, like gravitational potential energy, elastic potential energy, chemical potential energy, etc.
The additional energy, which an object obtains because of its motion, is called kinetic energy. The common example of use of kinetic energy is the movement of cycle. The rider of a cycle pedals the cycle to a certain speed and after that it moves with less pedaling on its own.
The kinetic energy so obtained by the cycle is used in facing the air-friction and the resistance of the road. If a dynamo is attached to the wheels of the cycle, then electrical energy is produced. The kinetic energy so produced can be used for converting into other forms of energy.
Extending the example of the cyclist, it can be observed that the kinetic energy of the moving cycle on a steep rise will be converted in to a gravitational potential energy once the cycle reaches the top point. On sliding down the slope, the cycle uses the potential energy to come down.
On reaching the top of the first peak, the kinetic energy with which the cars are pulled becomes the potential energy. With that, the cars not only slide down, but also move up the second peak. This process is repeated in the subsequent peaks, and finally, the cars are brought to a stop with the application of brake run.
A section of track at the end of the each block is used for stopping the train if necessary to avoid collision among the trains. Sensors fixed on the block detect the movement of the trains and send signals to the computer system operating the mechanism. | <urn:uuid:c6018b72-d038-404a-83b9-8ef549745479> | 3.859375 | 464 | Knowledge Article | Science & Tech. | 39.397729 | 95,516,883 |
A huge hydrogen generator at the Earth’s core-mantle boundary
Splitting water into hydrogen and oxygen is a major theme in the development of clean, abundant energy source. A new study lead by an international research group revealed that when water meets the iron core of the Earth, the extremely high pressures and temperatures existing at the core-mantle boundary can naturally cause water to split into hydrogen and a super oxidized iron dioxide. Both the released hydrogen and the retained oxygen in the dioxide have many far-reaching implications and consequences, including the behaviors of the core-mantle boundary as a huge hydrogen generator, the separation of the deep Earth's water and hydrogen cycles, and the accumulation of oxygen-rich patches.
The article, published in the National Science Review, is the result of an international collaboration among the Center for High Pressure Science and Technology Advanced Research (HPSTAR) in China and Carnegie Institution for Science in Washington, DC, and Department of Geosciences, Stanford University. They conducted high pressure-temperature experimental studies and theoretical calculations on the reaction between water and iron and probed the reaction products with synchrotron x-ray sources at the Advanced Photon Source, Argonne National Laboratory. They observed a series of intermediate composition iron oxides and iron hydride, with the final product of hydrogen and the new super oxidized iron dioxide.
The authors argue that based on our knowledge of water in the slabs subducting into the deep interior as a result of plate tectonics movement, 300 million tons of water per year could be carried down and meet iron in the core. This could generate a great amount of free hydrogen at the core-mantle boundary, 2900 kilometers beneath the surface. Although such rich hydrogen source is far beyond our reach, its upward movements returning to the surface via various paths as free hydrogen, as carbon hydrides through reactions with carbon, as hydrides through reaction with nitrogen, sulfur, and halogens, or as water again after recombined with oxygen on the way up, will be key issues for understanding geochemistry of deep volatiles.
Furthermore, the authors point out that continuous accumulation of super oxidized iron dioxide at the core-mantle boundary throughout the Earth history may create sizable domains detectable by seismic probes. Such domains may stay at the core-mantle boundary indefinitely without disturbance. However, they are out-of-the-place in terms of their very oxidized chemistry in the very reduced environment near the iron core. In the events that they were overheated by the core, a massive amount of oxygen could be released and erupted to reach the surface, causing colossal episode such as the Great Oxidation Event 24 billion years ago that put oxygen into the atmosphere and enabled aerobic life form like us.
"This newly discovered water-splitting reaction at the middle Earth affects geochemistry from the atmosphere to the deep interior," said the lead-author Ho-kwang Mao. "Many previous theories need to be re-examined now."
See the article: When water meets iron at Earth's core-mantle boundary
Ho-Kwang Mao, Qingyang Hu, Liuxiang Yang, Jin Liu, Duck Young Kim, Yue Meng, Li Zhang, Vitali B. Prakapenka, Wenge Yang, Wendy L. Mao
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Using cycling to explain why physics isn’t a drag
Scientists and teachers have combined to develop a simple spreadsheet-based method of teaching aerodynamic drag to 14 and 15 year olds. By measuring the speed of one of their classmates riding a bike, taking a photo to in order to measure the frontal area of the cyclist, the students were able to calculate the drag co-efficient.
The results are published today, 11th December 2015, in the journal Physics Education.
“Usually, describing a realistic motion including aerodynamic drag would be beyond the scope of a secondary physics course. However, I realised that this could be done fairly easy for a bike slowing down by aerodynamic drag” explains Florian Theilmann, an author of the paper who is based at the Weingarten University of Education in Germany.
“In a common physics class, physics seems to be presented in a very simplified way.” Theilmann continues. “Sure, that helps you to do easier calculations or some experiments but then it is less connected to real life.”
The researchers and teachers setup an experiment where a student on a bike was asked to pedal up to a certain point and then call out their speed as they passed markers on the way. The students also measured the rolling friction of the bike on the surface by pulling the bike along using a dynamometer for 10 meters.
These data were then fed into an excel spreadsheet where the students could vary the aerodynamic drag to match an ‘ideal’ plot against the plot of their experimental data.
“It might be because it was near the end of the year, or because we were doing something quite different, but the students seemed very engaged with the project.” Theilmann adds.
Theilmann is also confident that the computer will change how physics is taught.
“In the 19th century, it was necessary to understand how to do extremely sophisticated maths in order to do the more sophisticated physics” he explains. “But today, the computer has completely changed this – now problems are much simpler to calculate – so we’re able to address much more complex problems and open up new frontiers in science.”
Theilmann hopes to work on adapting more real-life physics problems to the classroom, including his current work on simple experiments with his own students such as the rate of flow of water out of a jug or the cooling down of a cup of tea. | <urn:uuid:c5f31832-dff5-41b5-a3e8-56927d06e2c8> | 2.84375 | 508 | News Article | Science & Tech. | 43.755882 | 95,516,908 |
1. Explain why the absorption lines of an element have the same wavelengths as the emission lines of that element.
2. Make up your own mnemonic to help you remember the sequence of spectral classes.
3. Why does convection develop about 70% of the way from the Sun's center to its surface?
4. What do we mean when we say that the Sun has a temperature of 5800K?
5. What evidence do we have that there is a relationship between sunspots and the temperature of the Earth?
6. What are radio and infrared radiation more useful than visible light in studying molecular clouds?
7. What evidence do we have that young stars are rounded by dusty disks rather than complete spherical shells of dust?
8. Why can't hydrogen fusion and helium fusion go on at the same time at the center of a star?
9. Suppose two single stars form at the same time. They have the same masses and chemical compositions. What can be said about the evolution of the two stars from that point forward?
10. In cluster 1, the main sequence extends from spectral class O to spectral class K. In cluster 2, there are no main sequence stars cooler than spectral class G. Which cluster is older and how do we know?© BrainMass Inc. brainmass.com July 19, 2018, 6:04 am ad1c9bdddf
1. Let us take the case of Hydrogen atom. It contains only one electron. The spectral lines are formed due to the transition of electron from an upper level to the lower level or vice versa. The single electron in the hydrogen atom gets a quantum energy and jumps to an upper level means an absorption line occured in that spectrum. After some time it will emit the same quanta of energy and comes back to the earlier energy level. Another thing to remember is that the energy between two levels is constant for a particular element. The energy levels of an electron around a nucleus are given by:
where is R∞ the Rydberg constant, Z is the Atomic number, n is the principal quantum
number, h is Planck's constant, and c is the speed of light. The Rydberg levels depend
only on the principal quantum number n.
2. The classic mnemonic for the spectral sequence O B A F G K M is Oh Be A Fine Girl, Kiss Me. Other favorite mnemonics for the spectral sequence include: Old, Bald, And Fat Generals Keep Mistresses , and
Oh Boy, An F Grade Kills Me.
3. For stars, the preferred way of energy transportation from the interior to the surface depends on many factors, such as temperature, pressure and the detailed chemical composition of the stellar matter. In the outer layers of the Sun, energy is primarily transported by convection, while radiation is the dominant form of energy transport in the
interior regions. Stars with a mass only slightly larger than that of the Sun (~10% larger) have convective cores and only a shallow outer convective layer. These ...
Fundamental question on the sun and its relation to stars and the earth are answered. | <urn:uuid:569091bb-e9c7-462e-802c-ccdaf1913d71> | 3.828125 | 647 | Content Listing | Science & Tech. | 65.985922 | 95,516,924 |
Getting the Current Date in PHP
In this brief lesson we look at how we can obtain the current date in PHP.
There are several methods but the easiest is to just use the date() function with passed in parameters.
For example, we can use 'Y-m-d' to represent the Year, month and day:
<?php echo 'Current Date: '. date('Y-m-d');
The output will be:
Current Date: 2018-01-10
If you would like to learn more about PHP then enrol in the PHP for Beginners course.
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Become a member and get access to the member only area of this site.LEARN MORE
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FREE Code Snippets
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|Schreibers' bat, Miniopterus schreibersi|
Miniopterus (bent-winged bat, long winged bat) is the only genus of bats in the family Miniopteridae. The genus had been placed in its own subfamily among vesper bats, Miniopterinae, but is now classified as its own family.
Bent-winged bats are typically small (total length c. 10 cm, wingspans 30–35 cm, mass less than 20 g), with broad, short muzzles. The cranium is bulbous and taller than the snout, a feature shared with woolly bats and mouse-eared bats. This combination of features was likely present in the common ancestor of the vesper bats. They have two tiny, vestigial premolars between the upper canines and first large premolar. Unlike other bats, they lack a tendon-locking mechanism in their toes.
The common name of bent-winged bat refers to the group's ability to fold back their extra-long third finger when the wings are folded. This finger gives the bats long, narrow wings.
In 2017, evidence of deltaretroviruses was found in the genome of the Miniopteridae. Deltaretroviruses only affect mammals, and this was the first evidence that they affected bat species. The presence of the deltaretrovirus in multiple Miniopterid species suggests that the virus was present in the family before speciation 20 million years ago. The evolutionary history of deltaretroviruses is important because they cause leukemia in humans.
- Genus Miniopterus - long-winged bats
- Miniopterus aelleni
- African long-fingered bat, Miniopterus africanus
- Little bent-wing bat, Miniopterus australis
- Miniopterus brachytragos
- Eger's long-fingered bat, Miniopterus egeri
- Miniopterus fossilis (fossil)
- Lesser long-fingered bat, Miniopterus fraterculus
- Eastern bent-wing bat, Miniopterus fuliginosus
- Southeast Asian long-fingered bat, Miniopterus fuscus
- Miniopterus gleni
- Miniopterus griffithsi
- Miniopterus griveaudi
- Greater long-fingered bat, Miniopterus inflatus
- Miniopterus macrocneme
- Miniopterus maghrebensis
- Western bent-winged bat, Miniopterus magnater
- Miniopterus mahafaliensis
- Miniopterus majori
- Manavi long-fingered bat, Miniopterus manavi
- Intermediate long-fingered bat, Miniopterus medius
- Least long-fingered bat, Miniopterus minor
- Miniopterus mossambicus
- Natal long-fingered bat, Miniopterus natalensis
- Miniopterus newtoni
- Australasian bent-winged bat, Miniopterus oceanensis
- Philippine long-fingered bat, Minopterus paululus
- Peterson's long-fingered bat (Miniopterus petersoni]])
- Small bent-winged bat, Miniopterus pusillus
- Loyalty bent-winged bat, Miniopterus robustior
- Common bent-wing bat, Miniopterus schreibersii
- Miniopterus shortridgei
- Miniopterus sororculus
- Great bent-winged bat, Miniopterus tristis
- Miniopterus zapfei (fossil)
Bent-winged bats occur in southern Europe, across Africa and Madagascar, throughout Asia, and in Australia, Vanuatu and New Caledonia. One species, the common bent-wing bat, inhabits the whole of this range. The group rapidly colonized much of this area in the last 15,000 years.
- "Bent-winged bats: wide ranges, very weird wings (vesper bats part III)". Retrieved 2015-05-07.
- Farkašová, H., Hron, T., Pačes, J., Hulva, P., Benda, P., Gifford, R. J., & Elleder, D. (2017). Discovery of an endogenous Deltaretrovirus in the genome of long-fingered bats (Chiroptera: Miniopteridae). Proceedings of the National Academy of Sciences, 201621224.
- Monadjem, A.; Goodman, S.M.; Stanley, W.T.; Appleton, B. (2013). "A cryptic new species of Miniopterus from south-eastern Africa based on molecular and morphological characters". Zootaxa. 3746 (1): 123–142. doi:10.11646/zootaxa.3746.1.5.
- Goodman, S. M., K. E. Ryan, C. P. Maminirina, J. Fahr, L. Christidis, and B. Appleton. 2007. Specific status of populations on Madagascar referred to Miniopterus fraterculus (Chiroptera: Vespertillionidae), with description of a new species. Journal of Mammalogy, 88:1216-1229.
- Goodman, S.M., Maminirina, C.P., Weyeneth, N., Bradman, H.M., Christidis, L., Ruedi, M. & Appleton, B. 2009. The use of molecular and morphological characters to resolve the taxonomic identity of cryptic species: the case of Miniopterus manavi (Chiroptera: Miniopteridae). Zoologica Scripta 38: 339-363
- Mein, P. and Ginsburg, L. 2002. Sur l'âge relatif des différents karstiques miocènes de La Grive-Saint-Alban (Isère). Cahiers scientifiques, Muséum d'Histoire naturelle, Lyon 2:7–47.
- Miller-Butterworth, C., Murphy, W., O'Brien, S., Jacobs, D., Springer, M. and Teeling, E. 2007. A family matter: Conclusive resolution of the taxonomic position of the long-fingered bats, Miniopterus. Molecular Biology and Evolution 24(7):1553–1561.
- Simmons, N. B. 2005. Order Chiroptera. pp. 312–529 in Mammal Species of the World a Taxonomic and Geographic Reference. D. E. Wilson and D. M. Reeder eds. Johns Hopkins University Press, Baltimore.
- Furman, A., Öztunç, T. & Çoraman, E. 2010b. On the phylogeny of Miniopterus schreibersii schreibersii and Miniopterus schreibersii pallidus from Asia Minor in reference to other Miniopterustaxa (Chiroptera: Vespertilionidae). Acta Chiropterologica 12, 61-72.
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Pietsch, R. J. Arnold & D. J. Hall, 2009
The psychedelic frogfish (Histiophryne psychedelica) is a yellow-brown or peach colored frogfish named for its pink and white stripes arranged in a fingerprint pattern. The fish is from waters near Ambon Island and Bali, Indonesia.
The psychedelic frogfish was first described in 2009 by Pietsch, Arnold, and Hall in the scientific journal Copeia, where they described it as having "a remarkable pigment pattern of white swirling stripes", hence their use of the term psychedelic. The psychedelic frogfish has been known to reach a length of 15 centimetres (5.9 in). The skin of the psychedelic frogfish is flabby and fleshy, like other frogfishes. As a member of the order Lophiiformes, it has no scales. The skin covers the dorsal and ventral fins of the fish, which aid in camouflaging the fish. The skin may be covered in protective mucus.
The psychedelic frogfish is different from many other anglerfishes in that it has a tiny luring appendage on its forehead. It has a relatively flat face with a mouth smaller than that of most anglerfishes.
The coloring of the skin is a pattern of yellowish brown or peach colored stripes. This pattern covers the entire fish, including its fins, except for the hidden skin that is exposed when the lips are stretched forward, which is pale in color. At the margins, the skin can appear to be turquoise, although the exact nature of this coloration is unclear. Unlike some frogfishes, the psychedelic frogfish's color never changes, even if the habitat changes, and its offspring maintain that color as well. The fingerprint pattern, like the stripes on a zebra or the spots on a humpback whale's tail, is unique to each individual. This allows researchers to easily track multiple psychedelic frogfish in the wild and still identify them from any angle.
The face of the psychedelic frogfish is flattened; the cheeks and chin of the fish are extended laterally, much like the sides of a collapsible paper orb. The fish is able to both expand its head and extend its mouth forward, thus expanding the head and giving it a more elongated shape more often seen in large fish. The fish employs this behavior periodically when not feeding, as though yawning.
The psychedelic frogfish has so far been positively identified only at Ambon Island, Indonesia. It has been found in coral rubble, where it may be camouflaged from predators, though the location is primarily considered a 'muck' dive with few corals in the area. The fish have so far been found in locations where the water is 5 to 7 metres (16 to 23 ft) deep, about 20 metres (66 ft) away from the shoreline. Occasionally, the current in these areas is so strong that it makes it nearly impossible for the fish to swim, but usually the current is only mild.
The coloration of the fish may be reminiscent of a number or hermatypic corals such as Symphyllia sinuosa, Leptoseris explanata, Pachyseris rugosa, Platygyra ryukyuensis, Pectinia lactuca, and Caulastrea furcata, all located in the Indo-West Pacific area.
The psychedelic frogfish moves by walking on its pectoral fins over the seafloor, and has been observed using its fins to push off from the sea floor while at the same time shooting water through its gills to propel itself forward via jet propulsion. When doing so, the fish takes on a ball shape, and its behavior takes on that of a bouncing beach ball in the wind. These modes of locomotion are quite common for frogfishes, although rare for other fish.
Instead, the psychedelic frogfish is presumed to strategically block off tight crevices which serve as passages to chambers in rocks and coral. The psychedelic frogfish was reported to wriggle itself very tightly into these holes, pushing with its fins, often for as long as two minutes before making its way inside the hole. Its skin may be covered with a protective mucus that aids in protecting it from scratches. This may also be an artifact of divers causing a fright response, especially when using high-powered strobes on underwater cameras.
The psychedelic frogfish is relatively defenseless, but by hiding in these tight passages it is highly unlikely that any fish capable of swallowing it will be able to reach it. The combination of camouflage and the tight cavities in which it might hide makes it virtually impossible to find a psychedelic frogfish without overturning rocks and coral. According to Andy Shorten, co-owner of the Maluku Divers diving facility where the fish was discovered, "Seeking out these fish is probably going to be like the Holy Grail of divers for a while."
It is not known what the purpose is of the frilled cheeks and chin, although Pietsch, Arnold, & Hall hypothesize that these serve the same function as whiskers on a cat, which is to detect movement of potential predators. It is also hypothesized that the ball-like shape which the psychedelic frogfish takes on when swimming in the open may be a form of camouflage. When assuming this shape, the fish looks much less like a fish and more like a piece of debris bouncing along the reef.
One female psychedelic frogfish laid a cluster of about 220 eggs. Like all members of the genus Histiophryne, the female wrapped its caudal, dorsal, and anal fins around the cluster of eggs, hiding it from view. As the fish had already spawned when it was observed carrying the eggs, the length of time to hatching is unknown.
In June 1992, a shipment of assorted fishes from Bali, Indonesia, to the Dallas Aquarium at Fair Park revealed "something different"— two curious-looking anglerfish that became known as the "paisley anglers". They were in "very poor condition", and they died that same month. The specimens were preserved and sent to Pietsch for identification, along with a photo, although the photo was poor quality. However, after having been fixed in formalin and preserved in ethanol, their colors faded to a solid white, and their frilled faces lost their distinct frill shape. When the fish were analyzed, they were misidentified as cryptic anglerfish (Histiophryne cryptacanthus). These specimens were preserved and placed on a shelf. No one returned to them until their recent rediscovery in 2008.
The species was first photographed in the wild during its second sighting in January 2008 by Buck Randolph, Fitrie Randolph and Toby Fadirsyair of Maluku Divers, located in Ambon, Indonesia. This quickly made headlines across American and Indonesian online newspapers, and the species was named one of the top 10 species discovered in 2009 by the International Institute for Species Exploration.
Researchers were not sure how to classify it, since it was so different from any other known fish. The nearest genus, Histiophryne, had so many differences it was debated whether the fish deserved its own genus. In fact, it was even considered that the new fish did not belong in the Antennariidae family. However, DNA tests, which are today's standard for making the final call on whether a species is new, proved that the fish belonged in the genus Histiophryne.
Ichthyologists Pietsch, Arnold, and Hall collected a holotype from the Laha I dive site at Maluku Divers on April 2, 2008. They discovered that the fish, when fixed in formalin and preserved in ethanol, shrank 23% (especially the fleshy cheeks and chin) within four months and hardened considerably. The colors all faded to a solid white, but when viewed using a dissecting microscope, the stripes were again visible. These observations were consistent with the mysterious paisley anglers from Bali in 1992. This was subsequently tested on the two specimens saved from 1992, and the stripes could still be found using this method.
|Wikispecies has information related to Histiophryne psychedelica|
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- Pietsch, T., Arnold, R., and Hall, D. (2009). "A bizarre new species of frogfish of the genus Histiophryne (Lophiiformes: Antennariidae) from Ambon and Bali, Indonesia". American Society of Ichthyologists and Herpetologists. Retrieved March 1, 2009.
- "DNA evidence is in, newly discovered species of fish dubbed H. psychedelica". University of Washington. February 24, 2009. Retrieved February 27, 2009.
- "New species of fish discovered that would rather crawl than swim". Environmental News Network. April 3, 2008. Retrieved April 3, 2008.
- "Possible new species of frogfish discovered by Maluku divers". Maluku Divers. 2008. Retrieved April 3, 2008.
- "'Dracula' fish and bombardier worm make top 10 list". LiveScience. 2010. Retrieved May 23, 2010.
- Cindy (April 7, 2008). "Maluku divers discover new species of frogfish". Reef eXplorers Network. Retrieved March 7, 2008. | <urn:uuid:c90ebede-8ed1-4283-ab86-5c1ddbb48e33> | 2.625 | 1,943 | Knowledge Article | Science & Tech. | 47.949834 | 95,516,938 |
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The team of Larry Atkins, Robert Ward and Darryl Landry made the finds on an isolated Michigan lake — they declined disclosing the exact location so as not to draw unwanted attention to the lake and its residents. In an interview with Space.com, Atkins said he plans on continuing the hunt for at least the next week.
The first find happened around 9 a.m. EST (1300 GMT), and Atkins discovered a second one himself just 15 minutes later. "It looked like a perfect black charcoal briquette, with a little snowdrift on top," Atkins told Space.com Thursday. Based on his two decades of experience hunting meteorites — fragments of rocks that remain after some space-rock fireballs break up in the atmosphere — he said there was no question it was from space. The rock showed up clearly on the fresh ice, although from a distance Atkins did question whether it was a small pile of leaves.
The finds had masses of between 20 and 100 grams, and were small enough to "fit in the palm of your hand," Atkins said. He added that from a quick look at the meteorites, they all appear related and they all looked like ordinary chondrites — the most common type of meteorite found on Earth. The team has already picked out one sample they plan to send to the Field Museum in Chicago, Atkins said. The rest they will keep for their personal collections, they said.
This weekend’s rainstorm was only the start of an abnormally wet pattern that will elevate the flood risk in the eastern United States into the end of the month.
The southeastern United States is facing the risk for damaging thunderstorms this weekend.
A pattern of persistent downpours, beginning with a rainstorm this weekend is likely to disrupt travel, hinder outdoor plans and projects and put summer heat on hold in the Northeast into early August.
Gusty winds caused blowing dust to sweep across the Las Vegas area on Saturday, creating dangerous conditions for travelers.
Near-record heat will set the stage for a heightened risk of wildfires in the southwestern United States, including Southern California, this week.
The intense record heat baking the south-central United States is expected to get trimmed back early this week, but a sweep of refreshing air is not on the horizon.
A deadly heat wave is expected to continue into early week across Japan as Ampil bypasses the region to the south.
An uptick in monsoon rainfall is expected to heighten the flood threat across eastern and northern India this week. | <urn:uuid:601c1e0e-a620-47aa-b7bf-c694e8219a3d> | 2.703125 | 521 | News Article | Science & Tech. | 55.304091 | 95,516,963 |
Scientists have re-discovered a fast-growing bacterial strain first described in 1955
Cyanobacteria, bacteria that obtain their energy through photosynthesis, are of considerable interest as bio-factories, organisms that could be harnessed to generate a range of industrially useful products.
Washington University in St. Louis
Engineered cyanobacteria could serve as miniature bio-factories that could sequester carbon, produce biofuel. pr synthesize valuable chemicals of novel pharmaceuticals. Looking to overcome sluggish growth, scientists have recovered a fast-growing strain from a contaminated culture in the UTEX algae collection.
Part of their appeal is that they can grow on sunlight and carbon dioxide alone and thus could contribute to lowering greenhouse gas emissions and moving away from a petrochemical-based economy.
However, familiar cyanobacterial strains grow more slowly than the bacterial and yeast bio-factories already in use, and their genetic and metabolic networks are not as well understood.
So it was exciting news when a group of scientists led by Himadri B. Pakrasi, PhD, the Myron and Sonya Glassberg/Albert and Blanche Greensfelder Distinguished University Professor in Arts & Sciences at Washington University in St. Louis, reported in the Sept. 30 issue of Scientific Reports that they have identified a fast growing cyanobacterial strain, called Synechococcus elongatus UTEX 2973.
Rapid growth may allow this cyanobacterial strain to outcompete contaminating ones and eventually to synthesize larger quantities of biofuel or other valuable products.
It also has the more immediate benefit of making it easier to do the experimental work needed to understand the bacterium well enough that it can serve as a “chassis” that can be retooled for a variety of purposes. Because other cyanobacterial strains grow sluggishly, it takes weeks or months to perform experiments with them that can be performed in E. coli or yeast in days.
The newly identified strain might ultimately prove useful for carbon sequestration, biofuel production, biosynthesis of valuable chemicals and the search for novel pharmaceuticals.
“What intrigues me most about these microbes is their ingenuity,” Pakrasi said. “They have somehow figured out how to multiply rapidly by using sunlight and carbon dioxide very efficiently.” Pakrasi, who also serves as director of Washington University’s International Center for Advanced Renewable Energy and Sustainability (I-CARES), and has been a prominent advocate of cyanobacterial synthetic biology for a decade.
Hiding in plain sight
Like the famous purloined letter, the cyanobacterial strain was hiding in plain sight — or to be precise, in a collection of algae cultures at the University of Texas in Austin. (Cyanobacteria are sometimes called blue-green algae, but this a misnomer.)
Although most cyanobacteria grow slowly, in 1955 two scientists at the University of Texas at Austin described a fast-growing cyanobacterial strain collected from a campus creek.
Whereas most strains grew by 5 to 8 percent per hour, this strain grew by 30 percent per hour. What’s more, it grew fastest at the relatively high temperature of 38 degrees C (104 degrees F). This strain was eventually deposited in the UTEX algae culture collection as Synechococcus leopoliensis UTEX 625.
However, at some point the UTEX 625 strain was contaminated and lost its rapid growth property. The Pakrasi lab obtained a frozen sample of the UTEX strain, and by careful coaxing under appropriate conditions, recovered a pure, fast-growing strain from the mixed culture of the deposited algae.
Under favorable conditions, the newly isolated strain grows at more than 50 percent per hour, the highest growth rate reported to date for any cyanobacterial strain, and almost twice as fast as a widely studied close relative. Since the new strain may not be the one that was described in 1955, the scientists deposited it in the UTEX algae collection as Synechococcus elongatus UTEX 2973.
Kicking the tires on the new model
To characterize the new strain, Washington University sequenced its genome. To the scientists’ surprise, the new strain turned out to be remarkably similar to a widely studied cyanobacterium, Synechococcus elongatus PCC 7942, originally discovered far away from Texas (in lakes in California), that grows only half as fast.
Since the genome sequences of the two strains are 99.8 percent identical, the genetic determinants of rapid growth almost certainly lie in the remaining 0.2 percent.
The proteomes (the set of proteins produced by an organism) of both of these strains were analyzed at the Environmental Molecular Sciences Laboratory, a Department of Energy national scientific user facility located at Pacific Northwest National Laboratory in Richland, Wash. This data, which covers 68 percent of the proteins the microbes produce, will guide further work with both strains.
The scientists also showed that the genome of the new strain can be easily manipulated, a characteristic essential to its use as a host for projects in synthetic biology.
“Cyanobacteria have the potential to be the ideal biofactories for sustainable carbon negative production of numerous compounds,” Pakrasi said. “This fast-growing strain should help to realize that dream.”
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Diana Lutz | newswise
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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...
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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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As in other eutrophied estuaries and coastal embayments, persistent hypoxia now routinely develops during summer in the mesohaline portion of the Neuse River estuary (North Carolina, USA). In response to interannual differences in hydrography, summer 1997 exhibited much more intense and widespread hypoxia than summer 1998, permitting inferences about impacts of hypoxia on food web dynamics by comparing system changes across these two summers. The trophic structure of the Neuse estuary now resembles the generic pattern for a degraded temperate estuary with (1) intense planktonic algal blooms and similarly high production of free-living bacteria, (2) trivial levels of abundance of rooted aquatic plants and benthic macroalgae, (3) depleted apex predators, and (4) functional extinction of the historically dominant benthic grazer, eastern oysters. Detailed carbon-flow models, based on comprehensive field data, demonstrated large differences between the two summers in trophic transfers and system dynamics. Largely because of greater mortality of benthic invertebrates from more intense hypoxia, total biomass of heterotrophs declined over summer by 51% in 1997 as compared to only 17% in 1998. Because net primary production increased over summer and herbivory in this system is predominantly benthic, the fraction of primary production consumed by herbivores declined over summer by 35% in 1997 and 29% in 1998. Influx of juvenile fishes and their rapid growth in the estuarine nursery over summer led to increases in energy demand by demersal fishes of 380% and 507% in the successive summers. Thus, hypoxia-enhanced diversion of energy flows into microbial pathways away from consumers and mass mortality of benthic invertebrates from bottom hypoxia occurred at the season of greatest demand by predatory fishes and crabs using the estuary as nursery. Average residence time of carbon in the ecosystem declined by 51% in 1997 and 29% in 1998. Total system throughput declined over summer 1997 while increasing in 1998, indicating the reduced capacity of the system to transfer carbon to higher trophic levels in the more hypoxic summer. Late-summer trophic pathways were characterized by greater numbers of cycles, but flows became increasingly dominated by microbial loops rather than transfers to consumers. Ecosystem trophic efficiency was only ϳ4%, lower than other estuaries similarly analyzed. System properties indicative of resil-iency of system function including development capacity, ascendancy, and flow diversity declined over summer 1997, while increasing or declining less in 1998. Thus, intensification of hypoxia caused dramatic reduction in the ecosystem's ability to transfer energy to higher trophic levels and rendered the ecosystem potentially less resilient to other stressors.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:b4babd4c-da24-46cb-af31-f94bb1bcd027> | 2.75 | 590 | Academic Writing | Science & Tech. | 7.144654 | 95,516,994 |
Local variables are specific to the local scope.
Global variables have global scope.
Object instance variables have scope within the current object.
class Square def initialize(side_length) @side_length = side_length # from w ww .java2 s . c o m end def area @side_length * @side_length end end a = Square.new(10) b = Square.new(5) puts a.area puts b.area
Object variables are prefixed with an @ symbol.
In the Square class, you assign the side_length provided to the class to @side_length.
@side_length, as an object variable, is then accessible from any other method inside that object.
That's how the area method can then use @side_length to calculate the area of the square represented by the object: | <urn:uuid:53672ae9-a13c-480e-beef-2e59da40aa50> | 3.78125 | 177 | Documentation | Software Dev. | 55.127047 | 95,517,003 |
Enjoy some of the extensive magazine, newspaper and web-based coverage of our work through the years.
Enjoy a sampling of print media featuring Dr. Nichols' efforts collected on ISSU.
Academy herpetologist Wallace J. Nichols is working with fisherman and using the latest technologies to help save threatened loggerhead sea turtles.
Loggerhead turtles have swum our oceans for 100 million years, inspiring folklore, songs, and art from Japan to California. Yet, not much is known about them.
Nichols knows why. Using a satellite tracking system, he has discovered that loggerheads born on Japanese beaches migrate 6,000 miles across the Pacific Ocean to Baja California, where they feast mainly on palm-sized pelagic red crabs (Pleuroncodes planipes). The transoceanic journey may take up to six years to complete.
They remain here until they reach maturity, about ten years, then navigate back to their natal Japanese beaches to mate and nest.
|Rodrigo Rangel, fisherman, with J Nichols, right, releasing a black turtle (Chelonia mydas ) in Bahia Magdalena in lower western Baja California. Photo credit: Terri Garland Photographyfirstname.lastname@example.org|
Using noninvasive "critter cams," Nichols will get an ever clearer picture of loggerhead turtle behavior. To deepen your knowledge of loggerheads and other sea turtles and to track their movements visit Nichols' Web site at www.wildcoast.net.
|Map of loggerhead migration route in the Pacific.|
Migrating loggerhead turtles (Caretta caretta) probably navigate using the Earth's magnetic field. This adult is escorted by a school of juvenile jack mackerel.
Photo credit: Mike Johnson /earthwindow.com
But Japan's nesting loggerheads are rapidly declining, as the turtles are vulnerable to fishing all along their range, from the coast of Mexico, to the deep ocean, to their nesting sites in Japan. Plastic bags are another serious threat; they look like jellyfish, a favorite of loggerheads, and tend to accumulate along the same current the turtles follow across the ocean.
Nichols works closely with fisherman, building upon their knowledge and skills to catch, tag, and recapture the turtles, even sometimes turning them into conservationists: two top poachers in Baja recently joined his team.
At the research center in Baja California the Wildcoast project conducts sea turtle education programs. Children learn about the five sea turtle species that occur in the region and how to measure them. At this meeting, children named one of the turtles being tracked "Max."
Photo credit: Louise Brooks
Recent research has confirmed what many boaters already know – you experience emotional, behavioral... continue
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Cosmic Ray Composition Around the Knee: Where are we?
One of the most intriguing feature of the Cosmic Ray (CR) spectrum is the presence of the “knee”. This is a sharp change of slope in the CR energy spectrum around 3 × 1015 eV. If we exclude the “ankle” (which is another, but less evident, change of slope in the highest energy region) the knee is the only remarkable feature of a spectrum which extends smoothly for more than 30 orders of magnitude. Discovered in 1958 , the existence of the “knee” still waits for an explanation. At present, there are several models that try to explain its presence. One of the most convincing models is that of diffusive shock acceleration in Supernova Remnants (SNR), since it can account for the total energy stored by the bulk of CR in the Galaxy (with an energy density ε ≃ 1 eV/cm3). Nevertheless, normal supernovas are expected to have neither high enough magnetic fields nor long enough shock lifetimes to accelerate particles to energies higher than 1015 eV. The coincidence of these values with the energy region of the knee is a strong indication that the change in the power law index may be due to a change in the acceleration mechanism. A direct check of this scenario is the observation of TeV Υ-rays from Supernovas, produced by the collision of TeV nucleons with the surrounding interstellar medium. Some experiments reported on the observations of TeV Υ-rays from Supernovas, but in all cases it has not been possible to assure that this emission is due to hadro-production processes.
KeywordsPrimary Mass Diffusive Shock Acceleration Cerenkov Light Relic Neutrino Cerenkov Detector
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Philip Metzger has been playing with mud. Experimenting, you could say, as he’s a planetary scientist at the University of Central Florida and co-founder of NASA’s Swamp Works lab. In any case, his lab has been stuffing Martian clay into cupcake decorating bags and extruding it into what Metzger himself admits sometimes look like an “animal dropping.”
But one man’s cupcake decorating with mud is another man’s prototyping of 3D-printing on Mars. And 3D-printing could solve the single biggest hurdle to a crewed Mars expedition: the cost of transporting everything humans need to survive on the red planet.
It’s a mass problem. The more mass you have to take, the more expensive it is to escape Earth’s gravity and get to Mars. And some of the heaviest cargo will be material to shelter astronauts from the radiation zipping through Mars’ thin atmosphere. With 3D-printing, you don’t need to bring shelter. You build it out of dirt or ice already on Mars.
NASA is all aboard the 3D-printing train. Last year, it unveiled winners of its first 3D-printed Mars habitat design challenge, and the architectural renders of the winning entries were all sleek and futuristic, as renders of unbuilt buildings always are . In reality, the current state of the art for Martian 3D-printing looks more like the clay logs Metzger has been documenting on Twitter.
Martian (sim) clay logs. Top: still damp. Bottom: vacuum dried. I'm surprised the 50% mix crumbled so badly. Need to repeat w/ more samples. pic.twitter.com/H9Sug4TB09— Dr. Phil Metzger (@DrPhiltill) October 13, 2016
If the technology looks low-tech, it’s deliberate. “We’re rethinking how to do space technology by taking cues from less developed parts of world,” says Metzger. The logic goes like this: If a valve breaks in a complex machine on Mars, an astronaut can’t go online to order a replacement with next day delivery. (It’s more like nine months, assuming Mars and Earth are in their most favorable alignment.) So the idea is to start simple and slowly build up technological capabilities: clay to metal to plastic to electronic equipment. Eventually, Mars will have the refineries and factories to make complicated machines itself. This is “bootstrapping,” and it’s Metzger’s vision for space exploration.
* * *
Should you ever find yourself doubting human ingenuity and persistence, spend a few minutes with the mesmerizing YouTube videos of Primitive Technology. In each video, a man—unnamed, silent, dressed only in shorts—goes out into the Australian outback with his bare hands. He might dig up some clay, make a coiled pot, and fire it in a small fire. He then goes back to the clay pit with his pot, this time able to carry more clay, and gathers enough material to build a kiln. He gets even more clay, makes tiles, and fires them in the kiln. Eventually, weeks later, he has an entire tiled hut, complete with mud walls and an underfloor heating system.
Each individual step is slow and unremarkable, but their cumulation—a tiled hut out of bare hands!—is awesome. This is bootstrapping, on the scale of one man.
American colonists, argues a 2011 NASA paper on space exploration, also bootstrapped their way through North America. They arrived with a few tools and scrabbled out a living in the harsh, unforgiving environment of New England. Simple pools begat more sophisticated tools, and over time, North America built up the shipyards and ports that turned it into a trading power. “Like colonial America, the growth process is a very slow and methodical,” the paper reads, “It will take years to evolve but in the end a very permanent infrastructure will emerge that will change how humans explore and develop space.”
In space—an environment where “harsh” is an understatement—bootstrapping might start with more sophisticated technology: robots. Robots are easier to send than humans, with their finicky needs for oxygen, food and water. But these robots, like the man in the Australian outback, will likely start with extremely simple tasks like digging up dirt. Dirt that could be turned into roads, blast walls, or shelters with enough 3D-printing ingenuity.
Metzger became intrigued by the idea when he realized Mars may have the same clay minerals as Earth. (The same is true for asteroids, which could be used as depots for interplanetary travel.) No one and nothing has ever returned to Earth with Martian dirt, of course, but probes and rovers of the decades have picked up chemical signatures hinting at the clay minerals.
So to test whether 3D printing clay could ever even work on Mars, he had to figure out how to simulate Martian clay on Earth. It helps that laws of chemistry and physics are the same. “You have chemical interaction on the surface of Mars that produce some fairly predictable products, like clays and sulfides,” says Daniel Britt, a collaborator and geologist at the University of Central Florida. “ And you know there’s environments on Earth that do the same thing.” The team called around to state geologists’ offices to find the mines with the different kinds of clay minerals to make Mars “simulant.”
With Mars simulant in hand, Metzger’s team wanted to test it in a vacuum chamber to mimic Mars’ thin atmosphere. Clay shrinks as it dries. And things dry very quickly in Mars’ thin atmosphere, which means the Martian simulant shriveled into shapes with little structural integrity.
Experiments with Mars clay recipes to 3D-print Martian buildings. The weak recipes cracked, fast-drying in Mars' atmosphere. pic.twitter.com/npFL899YOa— Dr. Phil Metzger (@DrPhiltill) October 12, 2016
This is a problem on Earth, too, though to a lesser degree, and Metzger points out, humans have come up with a solution. We don’t usually build walls out of big slabs of clay. Instead, we make bricks, fire them, and then lay them together with grout. “What we’re doing is investigating other methods to handle shrinkage,” says Metzger. “We don’t have to have a complicated grouting process.” That could mean adding soft squishy material—on Earth, this is usually straw; on Mars, it could be recycled spaceship material—to deal with the shrinkage. The key, again, is simplicity. The fewer different machines necessary, the fewer parts that can potentially break, and the easier it will be to keep construction on Mars humming.
By Metzger’s own account, this work is extremely early stage—as in extruding with a cupcake decorating bag rather than a 3D-printer early stage. This fast, cheap prototyping is the ethos of NASA’s Swamp Works lab, which Metzger co-founded and is still collaborating with after he retired from the space agency to work at the University of Central Florida.
Another disadvantage is the clay is that it requires water, which is frozen underground on Mars. Behrokh Khoshnevis at the University of Southern California has come up with a waterless method of 3D-printing on Mars. “We’re using material that is abundant on Mars. That is sulfur,” says Khoshnevis. His method uses sulfur as the binding agent in concrete; the catch is that the sulfur needs to be liquid (melting point 239 degrees F) and that requires a lot of energy via solar panels.
Whichever method ends up working, bootstrapping is about more than exploring space. Implicit in the argument for bootstrapping is an argument for colonizing space. The Apollo missions to the moon were “sorties”—in and out, everything you need is on the spaceship. If humans are actually going to build colonies or mines in space—and Metzger very much wants to—bootstrapping provides the technological blueprint for doing so. After all, bootstrapping is an accelerated version of technological development on Earth.
We want to hear what you think. Submit a letter to the editor or write to firstname.lastname@example.org. | <urn:uuid:5e3fcd6a-f030-4eac-85a6-e027fc2d5715> | 3.28125 | 1,826 | News Article | Science & Tech. | 54.303 | 95,517,023 |
Introduction Probaility and Statistics
by Muhammad El-Taha
Publisher: University of Southern Maine 2003
Number of pages: 147
Topics: Data Analysis; Probability; Random Variables and Discrete Distributions; Continuous Probability Distributions; Sampling Distributions; Point and Interval Estimation; Large Sample Estimation; Large-Sample Tests of Hypothesis; Inferences From Small Sample; The Analysis of Variance; Simple Linear Regression and Correlation; Multiple Linear Regression.
Download or read it online for free here:
by Brenda Meery - CK-12.org
CK-12 Foundation's Basic Probability and Statistics– A Short Course is an introduction to theoretical probability and data organization. Students learn about events, conditions, random variables, and graphs and tables that allow them to manage data.
by Marco Taboga - statlect.com
This e-book is organized as a website that provides access to a series of lectures on fundamentals of probability, statistics and econometrics, as well as to a number of exercises on the same topics. The level is intermediate.
by Allen B. Downey - Green Tea Press
Think Stats is an introduction to Probability and Statistics for Python programmers. This new book emphasizes simple techniques you can use to explore real data sets and answer interesting statistical questions. Basic skills in Python are assumed.
by David A. Kenny - John Wiley & Sons Inc
This text is a general introduction to the topic of structural analysis. It presumes no previous acquaintance with causal analysis. It is general because it covers all the standard, as well as a few nonstandard, statistical procedures. | <urn:uuid:dc1cb043-34d6-421f-bc55-83768ab6af4f> | 2.609375 | 338 | Content Listing | Science & Tech. | 23.551383 | 95,517,029 |
Every day, every moment, are carried out discoveries in the world of science, technology, health, climate change and much more. We will share with you what is happening in our world. We will be passing on a summary of the most important discoveries.The path towards wealth depends crucially on two words: work and savings. Benjamin Franklin.
Science is defined as the body of knowledge obtained based on a specific method. Science is research, which was later described in an orderly way, providing expertise in a field. It is how to achieve new knowledge, considered valid until there is no rebuttal. This indicates that science is not an unquestionable truth.
Features that identify science: systematic, cumulatively, methodical, interim, verifiably, specialized product of an open and scientific research.
From the Greek Tekne, which means technical, trade, and logos, which means science and knowledge.
The concept Technology covers a wide range of techniques, processes and knowledge, we are used to construct and design objects which are met with a host of needs of human beings.
Consequence of technology is the science and engineering, where many of the advances beyond the concepts outlined.
Nanotechnology, shortened to "nanotech", is the study of manipulating matter on an atomic and molecular scale. Generally nanotechnology deals with structures sized between 1 to 100 nanometer in at least one dimension, and involves developing materials or devices within that size. Quantum mechanical effects are very important at this scale.
Nanotechnology is very diverse, ranging from extensions of conventional device physics to completely new approaches based upon molecular self-assembly, from developing new materials with dimensions on the nanoscale to investigating whether we can directly control matter on the atomic scale. Read more
Recent PublicationsResearchers make and test atom-thick boron's unique domains
Defects are often observed when making borophene, the single-atom form of boron, but unlike in other two-dimensional materials, these mismatched lattices can assemble into ordered structures that preserve the material's metallic nature and electronic properties.
Mon, 16 Jul 2018 16:45:15 EDT
A safe and effective way to whiten teeth
In the age of Instagram and Snapchat, everyone wants to have perfect pearly whites. To get a brighter smile, consumers can opt for over the counter teeth-whitening treatments or a trip to the dentist to have their teeth bleached professionally. But both types of treatments can harm teeth. Researchers have now developed a new, less destructive method.
Wed, 18 Jul 2018 10:47:32 EDT | <urn:uuid:2afb6050-c152-4cdc-a702-cb18afb908f4> | 2.6875 | 532 | Content Listing | Science & Tech. | 30.386719 | 95,517,030 |
Jul 16, 2018 to Jul 18, 2018, Asilomar Conference Center, Monterey CA
Pre-Conference workshops: Sunday July 15, 2018
Evolving geospatial technologies give us innovative ways to view, analyze and interpret ever more complex data about the earth’s resources. We predict species movements, map habitats to finer scales, project climate change impacts and model forest fire scenarios. Building on the latest scientific understanding, we create credible and persuasive information to support our conservation planning, policies and actions.
This is crucial work, yet we can get lost in the modeling and technology for conservation and forget the positive aspects of the human dimensions of the landscapes we work to conserve. The traditional and local knowledge of communities—the people—that reside in a landscape are integral to the conservation process. Knowledge of culturally significant locations and resources need to be integrated in our geospatial thinking about conservation. Communities honor and cherish lands connected to historical uses and subsistence resources, areas of spiritual importance, medicinal importance, and places of much loved recreational activities. And different communities view their connections to their place in unique ways.
How do we as GIS professionals work as members of, or partners with, local communities to capture and integrate this information? What is our role in building the respect for all people connected to the landscape? Just as important, these local values help define why we do the work that we do to use geospatial technology to conserve the land, water and all that make up our landscapes for future.
This year’s conference theme “Local Communities and Traditional Knowledge” draws our attention to how the land was shaped prior to colonization, and how we can integrate and use that knowledge to inform our collective decisions today. Come hear our keynote speakers, Jaime Pinkham (Citizen of the Nez Perce Tribe and Executive Director of the Columbia River Inter-Tribal Fish Commission) and Lilian Pintea (Vice President of Conservation Science at the Jane Goodall Institute) speak on traditional values of the land to local communities.
Come to this year’s conference to join your colleagues—professionals engaging in the many facets of conservation GIS. Meet our invited keynote speakers and Maps for Advocacy panelists. Hear new perspectives on GIS and conservation while making new friends and enjoying the beauty of a walk on the beach at Asilomar State Beach and Conference Grounds.
Use this link to book your room ASILOMAR! * Do not register with Asilomar directly; we have a block of rooms reserved. If you register directly with Asilomar, your reservation will not count toward our reserved block and we will be charged for all rooms that we do not fill.
* When you are redirected to the Asilomar site, you should see "Welcome to the Society for Conservation GIS at Asilomar' at the top of the page.
Dr. Lilian Pintea & Jaime Pinkham
Jane Goodall Institute & Columbia River Inter-Tribal Fish Commission
Maps for Advocacy
Important Dates and Deadlines
Extended: Early Bird Offer ends on March 16, 2018
Extended: Call for Abstracts ends on March 30, 2018
About Asilomar Conference Center, Monterey CA | <urn:uuid:765bf401-10ae-4d5b-94cb-8b0c4fc09e15> | 2.515625 | 671 | News (Org.) | Science & Tech. | 26.377896 | 95,517,038 |
Described in Nature Photonics,* the demonstration shows how next-generation atomic clocks at different locations could be linked wirelessly to improve geodesy (altitude mapping), distribution of time and frequency information, satellite navigation, radar arrays and other applications.
Clock signals of this type have previously been transferred by fiber-optic cable, but a wireless channel offers greater flexibility and the eventual possibility of transfer to and from satellites.
The stability of the transferred infrared signal matched that of NIST's best experimental atomic clock, which operates at optical frequencies.** Infrared light is very close to the frequencies used by these clocks, and both are much higher than the microwave frequencies in conventional atomic clocks currently used as national time standards. Operating frequency is one of the most important factors in the precision of optical atomic clocks, which have the potential to provide a 100-fold improvement in the accuracy of future time standards. But the signals need to be distributed with minimal loss of precision and accuracy.
The signal transfer demonstration was performed outdoors over a two-way wireless link using two laser frequency combs. A frequency comb generates a steady stream of ultrashort optical pulses with a spacing that can be synchronized perfectly with the "ticks" of an optical atomic clock.*** In the experiment, the two combs were synchronized to the same stable optical cavity, which serves as a stand-in for an optical atomic clock. Each comb pulse was sent from one of two locations on NIST's campus in Boulder, Colo., reflected off a mirror on a mesa behind the campus, and returned to the other site, traveling a total distance of two kilometers.
Researchers measured travel times for pulses traveling in opposite directions between the two sites. The cumulative timing differences and frequency instabilities were infinitesimal, just one million-billionths of a second per hour, a performance level sufficient for transferring optical clock signals.
The transfer technique overcomes typical wireless signal problems such as turbulence in the atmosphere—the phenomenon that makes images shimmer when it's very hot outside. Because turbulence affects both directions equally, it can be cancelled out. The transfer technique can also withstand signal losses due to temporary obstruction of the light path. The method should be able to operate at much longer distances, possibly even over future ground-to-satellite optical communication links as an added timing channel, researchers say.
The combs potentially could be made portable, and the low-power infrared light is safe for eyes. The research is funded in part by the Defense Advanced Research Projects Agency.
* F.R. Giorgetta, W.C. Swann, L.C. Sinclair, E. Baumann, I. Coddington, N.R. Newbury. Optical two-way time and frequency transfer over free-space. Nature Photonics. Published online April 28.
** See 2010 NIST press release, "NIST Pair of Aluminum Atomic Clocks Reveal Einstein's Relativity at a Personal Scale," at http://www.nist.gov/public_affairs/releases/aluminum-atomic-clock_092310.cfm.
*** For more on how frequency combs work, see http://www.nist.gov/public_affairs/releases/frequency_combs.cfm.
Laura Ost | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Materials Sciences
19.07.2018 | Earth Sciences
19.07.2018 | Life Sciences | <urn:uuid:a2cb7f26-087b-497b-830d-1f375dbe4fbe> | 3.765625 | 1,318 | Content Listing | Science & Tech. | 38.404453 | 95,517,044 |
An asteroid the size of a house will buzz Earth today (Oct. 12) but poses no risk of hitting our planet, scientists say.
The asteroid 2012 TC4 will pass Earth at a range of just 59,000 miles (95,000 kilometers)—about one-fourth the distance to the moon—when it makes its closest point today, NASA scientists said. The asteroid was discovered by astronomers on Oct. 4 and is about 56 feet (17 meters) across.
"Small asteroid 2012 TC4 will safely pass Earth Oct 12 at just .25 the distance to our moon's orbit," scientists with NASA's Asteroid Watch program wrote in a Twitter update this week. On average, the moon's orbit is about 238,000 miles (383,000 km).
The asteroid is large enough to be seen by backyard astronomers using a small telescope, the night sky events website Spaceweather.com has reported.
Near-Earth flybys of small asteroids like 2012 TC4 pass inside the orbit of the moon fairly often, Asteroid Watch scientists at NASA's Jet Propulsion Laboratory in Pasadena, Calif., explained. On Sunday (Oct. 7), the 100-foot-wide (32-meter) asteroid 2012 TV also passed inside the moon's orbit, missing Earth by about 158,000 miles (255,000 kilometers). | <urn:uuid:7dd9ea8d-9227-44ee-b316-11b9e33b39e8> | 3.25 | 270 | News Article | Science & Tech. | 73.080586 | 95,517,049 |
Needless to say, this and other similar reports have generated denial on the part of hydro industry-backed researchers. As a result, the International Rivers Network is calling on the United Nations and the Intergovernmental Panel on Climate Change to develop more definitive research on this topic. This issue is of particular concern as hundreds of millions of dollars in climate subsidies and carbon credits could be spent on hydroelectric projects, which might actually serve to intensify global warming while also destroying ecosystems.
Although large-scale hydroelectric facilities fail to qualify under most definitions of renewable energy, hydropower is generally agreed to be a relatively low carbon intensity form of electricity generation. However, a recent report by the International Rivers Network may change the collective perception of hydroelectricity, in particular tropical hydropower. According to 'Battling Over Bubbles: Big Hydro Hides its Role in Global Warming', "tropical hydropower reservoirs can have a greater impact on global warming than even their dirtiest fossil fuel plant rivals". The report indicates that the greenhouse gases in question, carbon dioxide and methane, are emitted from the rotting of flooded vegetation and other organic matter that is present in hydroelectric reservoirs. The release of water at a dam is subsequently compared to the opening of a "vast coke bottle". More specifically, the report suggests that as water is released from turbines there is an associated large and sudden release of gas bubbles. This has led some to estimate that "in 1990 hydropower dams in the Amazon caused between 3 and 54 times more global warming than modern natural gas plants generating the same amount of energy". | <urn:uuid:3a57234a-aa3f-4131-86d2-bfd63c43e213> | 3.40625 | 322 | News Article | Science & Tech. | 13.363333 | 95,517,069 |
Species Detail - Upland Sandpiper (Bartramia longicauda) - 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).
17 July (recorded in 1974)
23 December (recorded in 1986)
National Biodiversity Data Centre, Ireland, Upland Sandpiper (Bartramia longicauda), accessed 22 July 2018, <https://maps.biodiversityireland.ie/Species/10151> | <urn:uuid:f165709f-f590-4426-8149-e94583cf002b> | 2.84375 | 147 | Structured Data | Science & Tech. | 33.246137 | 95,517,076 |
UK astronomers Elizabeth Stanway, Andrew Bunker and Richard McMahon at the Institute of Astronomy, University of Cambridge, England, have used three of the most powerful telescopes in existence to identify some of the farthest galaxies yet seen. But at the same time, they have encountered a cosmic conundrum: it looks as if there were fewer galaxies forming stars at this early stage in the history of the Universe than in the more recent past. Their results, which will be published in the Monthly Notices of the Royal Astronomical Society, show for the first time, that astronomers may be probing back to the era when the first stars and galaxies were forming.
Stanway, Bunker and McMahon used the unique power of the Hubble Space Telescope and analysed publicly-available images taken in the direction of the southern hemisphere constellation of Fornax (the Oven) with the new Advanced Camera for Surveys as part of the Great Observatory Origins Deep Survey (GOODS) project. They identified half a dozen objects likely to be galaxies 95 per cent of the way across the observable Universe. The redshifts of these galaxies are about 6 and they are so far away that radiation from them has taken about 13 billion years to reach us. They existed when the Universe was less than a billion years old and seven billion years before the Earth and Sun formed. Intervening gas clouds absorbed visible light from them long before it reached Earth but their infrared light can be detected - and it is their infrared colours which lead the researchers to believe that they lie at such immense distances.
They also used infrared images taken with one of the 8-metre telescopes forming the Very Large Telescope (VLT) at the European Southern Observatory (ESO) in Chile to study these galaxies. "The ESO pictures allowed us to distinguish very distant galaxies at the edge of the observable Universe from objects nearby," said graduate student Elizabeth Stanway, who has identified the galaxies as part of her research for a doctorate in astrophysics at Cambridge.
Elizabeth Stanway | alfa
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:f29d4c7b-30e8-4e5d-b799-a0b3a4e0b123> | 3.859375 | 982 | Content Listing | Science & Tech. | 36.469157 | 95,517,078 |
Neomura is a possible clade composed of the two domains of life of Archaea and Eukaryota. The group was named by Thomas Cavalier-Smith in 2002. Its name means "new walls", reflecting his hypothesis that it evolved from Bacteria, and one of the major changes was the replacement of peptidoglycan cell walls with other glycoproteins. As of August 2017[update], the neomuran hypothesis is not accepted by most workers; molecular phylogenies suggest that eukaryotes are most closely related to one group of archaeans and evolved from them, rather than forming a clade with all archaeans.
Considered as a clade, the Neomura are a very diverse group, containing all of the multicellular species, as well as all of the most extremophilic species, but they all share certain molecular characteristics. All neomurans have histones to help with chromosome packaging, and most have introns. All use the molecule methionine as the initiator amino acid for protein synthesis (bacteria use formylmethionine). Finally, all neomurans use several kinds of RNA polymerase, whereas bacteria use only one.
There are several hypotheses for the phylogenetic relationships between archaeans and eukaryotes.
Three domains view
When Carl Woese first published his three-domain system, it was believed that the domains Bacteria, Archaea, and Eukaryota were equally old and equally related on the tree of life. However certain evidence began to suggest that Eukaryota and Archaea were more closely related to each other than either was to Bacteria. This evidence included the common use of cholesterols and proteasomes, which are complex molecules not found in most bacteria, leading to the inference that the root of life lay between Bacteria on the one hand, and Archaea and Eukaryota combined on the other, i.e. that there were two primary branches of life subsequent to the LUCA – Bacteria and Neomura (not then called by this name).
The "three primary domains" (3D) scenario was one of the two hypotheses considered plausible in a 2010 review of the origin of eukaryotes.
Derived clade view
In a 2002 paper, and subsequent papers, Thomas Cavalier-Smith and coworkers have promulgated a hypothesis that Neomura was a clade deeply nested with Eubacteria with Actinobacteria as its sister group. He wrote, "Eukaryotes and archaebacteria form the clade neomura and are sisters, as shown decisively by genes fragmented only in archaebacteria and by many sequence trees. This sisterhood refutes all theories that eukaryotes originated by merging an archaebacterium and an α-proteobacterium, which also fail to account for numerous features shared specifically by eukaryotes and actinobacteria."
These include the presence of cholesterols and proteasomes in Actinobacteria as well as in Neomura. Features of this complexity are unlikely to evolve more than once in separate branches, so either there was a horizontal transfer of those two pathways, or Neomura evolved from this particular branch of the bacterial tree.
Two domains view
As early as 2010, the major competitor to the three domains scenario for the origin of eukaryotes was the "two domains" (2D) scenario, in which eukaryotes emerged from within the archaea. The discovery of a major group within the Archaea, Lokiarchaeota, to which eukaryotes are more genetically similar than to other archaeans, is not consistent with the Neomura hypothesis. Instead, it supports the hypothesis that eukaryotes emerged from within one group of archaeans:
A 2016 study supports the 2D view. Its "new view of the tree of life" shows eukaryotes as a small group nested within Archaea, in particular within the TACK superphylum. However, the origin of eukaryotes remains unresolved, and the two domain and three domain scenarios remain viable hypotheses.
- Cavalier-Smith T (March 2002). "The phagotrophic origin of eukaryotes and phylogenetic classification of Protozoa". Int. J. Syst. Evol. Microbiol. 52 (Pt 2): 297–354. doi:10.1099/00207713-52-2-297. PMID 11931142.
- Gribaldo, Simonetta; Poole, Anthony M.; Daubin, Vincent; Forterre, Patrick & Brochier-Armanet, Céline (2010-10-01). "The origin of eukaryotes and their relationship with the Archaea: are we at a phylogenomic impasse?". Nature Reviews Microbiology. 8 (10): 743–752. doi:10.1038/nrmicro2426.
- López-García, Purificación & Moreira, David (2015). "Open Questions on the Origin of Eukaryotes". Trends in Ecology and Evolution. 30 (11): 697–708. doi:10.1016/j.tree.2015.09.005. PMC .
- Hug, Laura A.; Baker, Brett J.; Anantharaman, Karthik; Brown, Christopher T.; Probst, Alexander J.; Castelle, Cindy J.; Butterfield, Cristina N.; Hernsdorf, Alex W.; Amano, Yuki; Ise, Kotaro; Suzuki, Yohey; Dudek, Natasha; Relman, David A.; Finstad, Kari M.; Amundson, Ronald; Thomas, Brian C. & Banfield, Jillian F. (2016-04-11). "A new view of the tree of life". Nature Microbiology. 1 (5): 16048. doi:10.1038/nmicrobiol.2016.48.
|Wikispecies has information related to Neomura|
|Wikimedia Commons has media related to Neomura.|
- Cavalier-Smith T (1987). "The origin of eukaryotic and archaebacterial cells". Ann. N. Y. Acad. Sci. 503: 17–54. doi:10.1111/j.1749-6632.1987.tb40596.x. PMID 3113314.
- Cavalier-Smith T (January 2002). "The neomuran origin of archaebacteria, the negibacterial root of the universal tree and bacterial megaclassification". Int. J. Syst. Evol. Microbiol. 52 (Pt 1): 7–76. doi:10.1099/00207713-52-1-7. PMID 11837318.
- Cavalier-Smith T (2006). "Rooting the tree of life by transition analyses". Biol. Direct. 1: 19. doi:10.1186/1745-6150-1-19. PMC . PMID 16834776.
- Skophammer RG, Servin JA, Herbold CW, Lake JA (August 2007). "Evidence for a gram-positive, eubacterial root of the tree of life". Mol. Biol. Evol. 24 (8): 1761–8. doi:10.1093/molbev/msm096. PMID 17513883.
- Cox, C. J.; Foster, P. G.; Hirt, R. P.; Harris, S. R.; Embley, T. M. (10 December 2008). "The archaebacterial origin of eukaryotes". Proceedings of the National Academy of Sciences. 105 (51): 20356–20361. doi:10.1073/pnas.0810647105. PMC . PMID 19073919.
- Cavalier-Smith, T. (2 September 2014). "The Neomuran Revolution and Phagotrophic Origin of Eukaryotes and Cilia in the Light of Intracellular Coevolution and a Revised Tree of Life". Cold Spring Harbor Perspectives in Biology. 6 (9): a016006–a016006. doi:10.1101/cshperspect.a016006. PMC . PMID 25183828. | <urn:uuid:068a69c2-d8bd-41bc-8a4e-bb3813c550b8> | 2.90625 | 1,761 | Knowledge Article | Science & Tech. | 57.493013 | 95,517,090 |
SVG Optimization 01
- Lesson 01: SVG Primer
SVG origin 0,0 is at the top left, coordinates are X,Y
Line 2: Draw a rectangle at 100,100. With no stroke or fill specified, it defaults to a black fill.
Line 3: Move to 200,200 without drawing. Line to 300,200.
Line 4: Same as line 4, but with a path command, if you leave out the L (line) command, and enter coordinates, L is assumed.
Line 5: Uses relative coordinates instead of absolute. Lowercase letters are used here to specify relative coordinates. Lowercase l means the next coordinate is relative to the the first coordinate. In this case, move 100px in the x direction, and 0 in the y direction.
Line 6: You can also leave out the lowercase l, it is assumed.
Line 7: Draw a square.
Line 8: Draw a circle with a radius of 50 in the same coordinates as the square. Notice the circle specifies coordinates by its center. If we want a square in the same location, we need to adjust its x and y coordinates.
Line 9: Draw a shape with a stroke and fill. Start at 200,700. Draw a line 100px horizontally and 0 vertically. Draw a line -50px horizontally and 50px vertically which is the bottom vertex of the triangle. z closes the shape.
There's an error in this code - a square showed up as black when I wanted blue because the color should be "#00f".
Modify your SVG code, it's often easier than using Inkscape!
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Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic. The aging process in human beings is easy to see. As we age, our hair turns gray, our skin wrinkles and our gait slows. However, rocks and other objects in nature do not give off such obvious clues about how long they have been around. So, we rely on radiometric dating to calculate their ages. Radiometric dating, or radioactive dating as it is sometimes called, is a method used to date rocks and other objects based on the known decay rate of radioactive isotopes. Different methods of radiometric dating can be used to estimate the age of a variety of natural and even man-made materials.
How accurate are Carbon 14 and other radioactive dating
The methods work because radioactive elements are unstable, and they are always trying to move to a more stable state. So, they do this by giving off radiation. This process by which an unstable atomic nucleus loses energy by releasing radiation is called radioactive decay. The thing that makes this decay process so valuable for determining the age of an object is that each radioactive isotope decays at its own fixed rate, which is expressed in terms of its half-life. So, if you know the radioactive isotope found in a substance and the isotope's half-life, you can calculate the age of the substance.
So, what exactly is this thing called a half-life? Well, a simple explanation is that it is the time required for a quantity to fall to half of its starting value. So, you might say that the 'full-life' of a radioactive isotope ends when it has given off all of its radiation and reaches a point of being non-radioactive. When the isotope is halfway to that point, it has reached its half-life. There are different methods of radiometric dating that will vary due to the type of material that is being dated.
Carbon 14 Radiometric Dating CSI
For example, uranium-lead dating can be used to find the age of a uranium-containing mineral. It works because we know the fixed radioactive decay rates of uranium-788, which decays to lead-756, and for uranium-785, which decays to lead-757. So, we start out with two isotopes of uranium that are unstable and radioactive. They release radiation until they eventually become stable isotopes of lead. These two uranium isotopes decay at different rates.
In other words, they have different half-lives. The half-life of the uranium-788 to lead-756 is 9. 97 billion years. The uranium-785 to lead-757 decay series is marked by a half-life of 759 million years. These differing rates of decay help make uranium-lead dating one of the most reliable methods of radiometric dating because they provide two different decay clocks.
This provides a built-in cross-check to more accurately determine the age of the sample. Uranium is not the only isotope that can be used to date rocks we do see additional methods of radiometric dating based on the decay of different isotopes. For example, with potassium-argon dating, we can tell the age of materials that contain potassium because we know that potassium-95 decays into argon-95 with a half-life of 6. 8 billion years. With rubidium-strontium dating, we see that rubidium-87 decays into strontium-87 with a half-life of 55 billion years.
By anyone's standards, 55 billion years is a long time. In fact, this form of dating has been used to date the age of rocks brought back to Earth from the moon. | <urn:uuid:72750046-9eb1-4243-b9e7-8904b95f6a6b> | 3.828125 | 769 | Knowledge Article | Science & Tech. | 51.368029 | 95,517,141 |
Discussion of the distribution and abundance of living organisms and how these properties are affected by interactions between the organisms and their environment
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I dunno, my teacher told me to talk about growth patterns that exhibit a sine graph... I've looked everywhere online to find a graph and a real world example but I just can't find one.
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what about population of preys and predators?
Cis or trans? That's what matters.
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Look up Lotka-Volterra equations, that should help.
Who is online
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Scientists from the USGS and the School of Ocean and Earth Science and Technology (SOEST) at UH studied more than 150 miles of island coastline (essentially every beach) and found the average rate of coastal change – taking into account beaches that are both eroding and accreting – was 0.4 feet of erosion per year from the early 1900s to 2000s. Of those beaches eroding, the most extreme case was nearly 6 feet per year near Kualoa Point, East O'ahu.
The shoreline along Makapuu Point, Oahu, Hawaii, was included in the study released today.
Credit: Brad Romine, University of Hawaii Sea Grant/ Hawaii Department of Land and Natural Resources
"The inevitable fate of the Hawaiian Islands millions of years into the future is seen to the northwest in the spires of French Frigate Shoals and the remnants of other once mighty islands, ancestors of today's Hawaii, but now sunken beneath the sea through the forces of waves, rivers, and the slow subsidence of the seafloor," explained USGS Director Marcia McNutt.
"These data have allowed State and County agencies in Hawai'i to account for shoreline change as early as possible in the planning and development process so that coastal communities and public infrastructure can be sited safely away from erosion hazards areas," said William J. Aila Jr., Chairperson, Department of Land and Natural Resources, State of Hawai'i. "This will vastly improve upon public safety and will ensure that Hawaii's beautiful beaches will be protected from inappropriate shoreline development."
Of the three islands, Maui beaches experienced the highest rates and greatest extent of beach erosion with 85% of beaches eroding. Erosion is the dominant trend of coastal change on all three islands with 71% of beaches eroding on Kaua'i and 60% of beaches eroding on O'ahu.
The researchers found that, although Hawai'i beaches are dominated by erosion as a whole, coastal change is highly variable along the shore – with 'cells' of erosion and accretion typically separated by 100s of feet on continuous beaches or by rocky headlands that divide the coast into many small embayments. Most Hawaii beaches are composed of a mix of sediment derived from adjacent reefs and from the volcanic rock of the islands. Sediment availability and transport are important factors in shoreline change, and human interference in natural processes appears to have impacted the measured rates of change. For example, more than 13 miles of beaches in the study were completely lost to erosion – nearly all previously in front of seawalls.
"Over a century of building along the Hawaiian shoreline, without this sort of detailed knowledge about shoreline change, has led to some development that is located too close to the ocean," said Dr. Charles Fletcher, UH Geology and Geophysics Professor and lead author. "A better understanding of historical shoreline change and human responses to erosion may improve our ability to avoid erosion hazards in the future."
The researchers used historical data sources such as maps and aerial photographs to measure shoreline change at more than 12,000 locations. Shoreline changes are measured in specialized Geographic Information System (GIS) software.
This analysis of past and present trends of shoreline movement is designed to allow for future repeatable analyses of shoreline movement, coastal erosion, and land loss. "The results of this research provide critical coastal change information that can be used to inform a wide variety of coastal management decisions," said Dr. Rob Thieler, sponsor of the study with the USGS.
The research was also supported by grants from a number of federal, state, and county agencies as well as non-profit organizations. The report, titled "National Assessment of Shoreline Change: Historical Shoreline Change in the Hawaiian Islands," is the sixth report produced as part of theUSGS's National Assessment of Shoreline Change project, which already includes the U.S. Gulf of Mexico and Atlantic coasts, as well as California. An accompanying report that provides the GIS data used to conduct the Hawaii coastal change analysis is being released simultaneously.Research Contact:
Marcie Grabowski | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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19.07.2018 | Life Sciences | <urn:uuid:c4db9853-0a07-473a-bc68-2df098761b1d> | 3.578125 | 1,508 | Content Listing | Science & Tech. | 37.956392 | 95,517,151 |
Carbon Nanotubes, long, thin cylinders of carbon, were discovered in 1991 by Sumio Iijima. These are large macromolecules that are unique for their size, shape, and remarkable physical properties. They can be thought of as a sheet of graphite (a hexagonal lattice of carbon) rolled into a cylinder. These intriguing structures have sparked much excitement in recent years and a large amount of research has been dedicated to their understanding. Currently, the physical properties are still being discovered and disputed. Nanotubes have a very broad range of electronic, thermal, and structural properties that change depending on the different kinds of nanotube (defined by its diameter, length, and chirality, or twist). To make things more interesting, besides having a single cylindrical wall (SWNTs), Nanotubes can have multiple walls (MWNTs)--cylinders inside the other cylinders See more. | <urn:uuid:715dc535-8a3a-458c-a091-34ace95656c9> | 3.609375 | 188 | Knowledge Article | Science & Tech. | 21.193333 | 95,517,170 |
Human Genome Exhibition Makes DNA Accessible to Public
News Jul 11, 2013
The Smithsonian Institution's first exhibition about genome science, Genome: Unlocking Life's Code, opens Friday, June 14, 2013, at the National Museum of Natural History in partnership with the National Human Genome Research Institute (NHGRI), a part of the National Institutes of Health.
The exhibition examines the complexities of the genome - the complete set of genetic or hereditary material of a living organism - and chronicles the remarkable breakthroughs that have taken place since the completion of the Human Genome Project a decade ago.
With cutting-edge interactives, 3D models, custom animations and engaging videos of real-life stories, the exhibition examines both the benefits and the challenges that genomics presents to modern society.
"This exhibition reflects a remarkably productive collaboration between components of two scientific icons of the U.S. government- the Smithsonian Institution and the National Institutes of Health," said Eric D. Green, M.D., Ph.D., director of NHGRI, one of the 27 institutes and centers that make up NIH.
Green continued, "Our ability to showcase the science of genomics to the roughly 7 million annual visitors of the National Museum of Natural History is profoundly exciting for the broader genomics research community."
The exhibition's opening celebrates the anniversaries of two landmark scientific discoveries: the 10th anniversary of the Human Genome Project's completion and the 60th anniversary of Drs. James Watson's and Francis Crick's discovery of DNA's double-helical structure. It will be open at the National Museum of Natural History through September 2014, after which the exhibition will travel throughout North America for about five years.
"Genomic research is a vital tool for exploring the mysteries of the natural world and it is an important part of Smithsonian science," said Kirk Johnson, the Sant Director of the National Museum of Natural History. "Genome: Unlocking Life's Code will help our visitors understand how genomics is transforming what we know about ourselves and how we make important life decisions."
From the moment visitors enter the approximately 2,900 square-foot exhibition, they will find themselves immersed in an interactive, futuristic environment that communicates the revolutionary nature of genomics.
The exhibition gives visitors a window into genomes that provides new ways of looking at themselves as individuals, as members of a family and a species, and as part of the diversity of life on Earth.
Genome: Unlocking Life's Code is organized around three content areas offering visitors personalized and interactive experiences that explore what a genome is (The Genome Within Us), how it relates to medicine and health (Your Genome, Your Health), and how it connects humans to all of life on the planet (Connections: Natural World and Genomic Journey).
Within each gallery, numerous topics are explored through the latest imagery on genomics, hands-on and media interactives, videos and other engaging content. Through examples of ways that genome science can affect their lives in ordinary and extraordinary ways, visitors will also come to learn how genomics can affect perspectives about health, identity, and the place of humans in the natural world.
Genome: Unlocking Life's Code will take visitors on a genomic journey from the present to the future:
The Genome Within Us: Upon arrival, museum-goers will be oriented at the center of the exhibition where they will explore how the genome is a part of their own bodies. Visitors will discover what a genome is, where it is located in the human body (in the cell nucleus), and how it works to regulate life, through introductory videos produced by the History channel. Visitors will see three-dimensional models of a human genome and watch interviews with Human Genome Project researchers.
Visitors can also participate in a social media interactive where they can explore the ethical, legal, and social implications of advancing DNA sequencing technologies, submit their responses on an interactive station and find out how their views compare with those of other visitors. An electronic news ticker display will provide an ongoing stream of recent developments in genomics.
Your Genome, Your Health: Guests can explore the many ways in which genome sequencing benefits patients through improved health care. They can learn about genes, genomic solutions to mysterious medical diseases, and, through a futuristic DNA interactive, search for the right medicine for a given disease. An interactive puzzle allows visitors to learn how genetic, environmental, and random factors influence risk for a particular disease.
Connections: Natural World and Genomic Journey: Visitors will learn about the ways that genomes reflect the connection of all life on the planet, human ancestry and evolution - and even human society. There will be an opportunity to learn more about how the Smithsonian is using new genomic technologies to preserve genetic diversity and study changes in our environment through the Global Genome Initiative and GGI's growing biorepository.
"Today, the Smithsonian is a leader in utilizing genomic research to understand the diversity of life on earth," said Jonathan Coddington, Ph.D., associate director for science at the National Museum of Natural History. "This exhibition provides a unique opportunity to showcase the cutting edge biotechnological research going on behind-the-scenes at the museum, and features some of our scientists' work on hot topics like bird strikes, butterflies, wine grapes, bio-coding, Tasmanian devils and the Global Genome Initiative. Thanks to genomics, we now have the tools to sequence every organism on the planet, allowing us to preserve genetic diversity, study changes in our environment and learn more about how these changes affect all life on earth."
In addition to the exhibition, a special educational website, Unlocking Life's Code (http://unlockinglifescode.org), was created to support the exhibition and provide additional educational materials beyond the walls of the museum. A program of ongoing educational events in Washington, D.C., is also being developed and will be announced on the website.
"Collaborating with the Smithsonian National Museum of Natural History in the development of the genome exhibition created an opportunity to educate the public about advances in genomics research" said Vence L. Bonham, Jr., J.D., chief of the education branch in NHGRI's Division of Policy, Communications and Education. "NHGRI engages communities across the country to explore genomics and health, but this is the first collaboration with the Smithsonian Institution, which will reach millions of visitors at the National Museum of Natural History."
The exhibition was made possible through the generous support of the Life Technologies Foundation, and other important sponsors, including Johnson & Johnson, Ancestry.com and The Brin Wojcicki Foundation.
Analytical Tool Predicts Disease-Causing GenesNews
Predicting genes that can cause disease due to the production of truncated or altered proteins that take on a new or different function, rather than those that lose their function, is now possible thanks to an international team of researchers that has developed a new analytical tool to effectively and efficiently predict such candidate genes.
Single Gene Change in Gut Bacteria Alters Host MetabolismNews
Scientists have found that deleting a single gene in a particular strain of gut bacteria causes changes in metabolism and reduced weight gain in mice. The research provides an important step towards understanding how the microbiome – the bacteria that live in our body – affects metabolism.READ MORE
Gotta Sample 'Em All! Underwater Pokéball Captures Ocean LifeNews
A new device developed by Wyss Institute reseachers safely traps delicate sea creatures inside a folding polyhedral enclosure and lets them go without harm using a novel, origami-inspired design. The ultimate aim is to allow the sea creatures to be (gently) analyzed in high detail.READ MORE
International Conference on Neurooncology and Neurosurgery
Sep 17 - Sep 18, 2018 | <urn:uuid:c70e756c-7416-424f-ab9a-666155b8c4b8> | 2.96875 | 1,602 | Content Listing | Science & Tech. | 21.855692 | 95,517,172 |
Nanocomposites based on layered double hydroxides (LDHs) have recently become a formidable research area due to their amendable properties and potential applications. The distinct properties of LDH polymer nanocomposites include a wide range of chemical compositions, structural homogeneity, unique anion exchanging ability, easy synthesis, high bound water content, memory effect, non-toxicity and biocompatibility. This means that LDH polymer nanocomposites have the potential for new and innovative applications.
Layered Double Hydroxide Polymer Nanocomposites presents a comprehensive overview of the recent innovative advances in the fabrication, characterization and applications of LDH polymer nanocomposites. As well as covering fundamental structural and chemical knowledge, this book also explores various properties and characterization techniques including microscopic, spectroscopic and mechanical behaviors. There is also a strong focus on the potential applications of LDH polymer nanocomposites, such as energy, electrical and electronic, electromagnetic shielding, biomedical, agricultural, food packaging and water purification functions.
This book provides comprehensive coverage of cutting-edge research in the field of LDH polymer nanocomposites and their future applications. This book will be an essential read for all academics, researchers, engineers and students working in this area.
- Fundamental knowledge of LDH polymer nanocomposites, including chemical composition, structural features and fabrication techniques
- Provides an analytical overview of the different types of characterization techniques and technologies
- Extensive review on cutting-edge research for potential future applications, in a variety of industries
1. An introduction to Layered Double Hydroxides (LDHs) 2. Chemical Modification of Layered Double Hydroxide 3. Fabrication Technologies of Layered Double Hydroxide Polymer Nanocomposites 4. Crystallization of Semi Crystalline Layered Double Hydroxide Polymer Nanocomposites 5. X-ray Diffraction Analysis of Layered Double Hydroxide Polymer Nanocomposites 6. Microscopic Characterization Techniques for Layered Double Hydroxide Polymer Nanocomposites 7. Spectroscopic Characterization Techniques for Layered Double Hydroxide Polymer Nanocomposite 8. Recent Advances in Spectroscopic Analysis of Layered Double Hydroxide Polymer Nanocomposites 9. Dynamic Mechanical Analysis of Layered Double Hydroxide Polymer Nanocomposites 10. Melt Rheological Properties of Layered Double Hydroxide Polymer Nanocomposites 11. Thermal Properties and Flame Retardant Characteristics of Layered Double Hydroxide Polymer Nanocomposites 12. Layered Double Hydroxide Polymer Nanocomposites for Energy Applications 13. Electrical and Electronic Applications of Layered Double Hydroxide Polymer Nanocomposites 14. Electromagnetic Shielding Applications of Layered Double Hydroxide Polymer Nanocomposites 15. Layered Double Hydroxide Polymer Nanocomposites for Biomedical Applications 16. Layered Double Hydroxide Polymer Nanocomposites for Agricultural Applications 17. Layered Double Hydroxide Polymer Nanocomposites for Food Packaging Applications 18. Layered Double Hydroxide Polymer Nanocomposites for Water Purification 19. Layered Double Hydroxide Polymer Nanocomposites for Catalysis
Professor Thomas is the Director of the International and Interuniversity Centre for Nanoscience and Nanotechnology and full professor of Polymer Science and Engineering at the School of Chemical Sciences of Mahatma Gandhi University, Kottayam, Kerala, India. He is an outstanding leader with sustained international acclaims for his work in Polymer Science and Engineering, Polymer Nanocomposites, Elastomers, Polymer Blends, Interpenetrating Polymer Networks, Polymer Membranes, Green Composites and Nanocomposites, Nanomedicine and Green Nanotechnology. Dr. Thomas's ground breaking inventions in polymer nanocomposites, polymer blends, green bionanotechnological and nano-biomedical sciences, have made transformative differences in the development of new materials for automotive, space, housing and biomedical fields. Professor Thomas has received a number of national and international awards which include: Fellowship of the Royal Society of Chemistry, Distinguished Professorship from Josef Stefan Institute, Slovenia, MRSI medal, CRSI medal and Sukumar Maithy award. He is in the list of most productive researchers in India and holds a position of No.5. Professor Thomas has published over 720 peer reviewed research papers, reviews and book chapters. He has co-edited 54 books published by Royal Society, Wiley, Wood head, Elsevier, CRC Press, Springer, Nova etc. He is the inventor of 4 patents. The h index of Prof. Thomas is 78 and has more than 26811 citations.Prof. Thomas has delivered over 300 Plenary/Inaugural and Invited lectures in national/international meetings over 30 countries. He has already supervised 74 Ph.D theses.
Saju Daniel is a senior research fellow of International and InterUniversity Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala, India. She is also an Asst. Professor at St Xavier's College Vaikom which is affiliated to M G University, Kottayam | <urn:uuid:1588748d-d0fc-469b-b797-03c356bbaaf7> | 2.515625 | 1,096 | Academic Writing | Science & Tech. | -7.456822 | 95,517,182 |
NAMEy0, y0f, y0l, y1, y1f, y1l, yn, ynf, ynl - Bessel functions of the second kind
SYNOPSIS#include <math.h> double y0(double x); double y1(double x); double yn(int n, double x); float y0f(float x); float y1f(float x); float ynf(int n, float x); long double y0l(long double x); long double y1l(long double x); long double ynl(int n, long double x); Link with -lm. Feature Test Macro Requirements for glibc (see feature_test_macros(7)): y0(), y1(), yn(): _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE y0f(), y0l(), y1f(), y1l(), ynf(), ynl(): _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 600
DESCRIPTIONThe y0() and y1() functions return Bessel functions of x of the second kind of orders 0 and 1, respectively. The yn() function returns the Bessel function of x of the second kind of order n. The value of x must be positive. The y0f() etc. and y0l() etc. functions are versions that take and return float and long double values, respectively.
RETURN VALUEOn success, these functions return the appropriate Bessel value of the second kind for x. If x is a NaN, a NaN is returned. If x is negative, a domain error occurs, and the functions return -HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively. (POSIX.1-2001 also allows a NaN return for this case.) If x is 0.0, a pole error occurs, and the functions return -HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively. If the result underflows, a range error occurs, and the functions return 0.0 If the result overflows, a range error occurs, and the functions return -HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively. (POSIX.1-2001 also allows a 0.0 return for this case.)
ERRORSSee math_error(7) for information on how to determine whether an error has occurred when calling these functions. The following errors can occur: Domain error: x is negative errno is set to EDOM. An invalid floating-point exception (FE_INVALID) is raised. Pole error: x is 0.0 errno is set to ERANGE (but see BUGS). No FE_DIVBYZERO exception is returned by fetestexcept(3) for this case. Range error: result underflow errno is set to ERANGE. No FE_UNDERFLOW exception is returned by fetestexcept(3) for this case. Range error: result overflow errno is not set for this case. An overflow floating-point exception (FE_OVERFLOW) is raised.
CONFORMING TOThe functions returning double conform to SVr4, 4.3BSD, POSIX.1-2001. The others are nonstandard functions that also exist on the BSDs.
BUGSOn a pole error, these functions set errno to EDOM, instead of ERANGE as POSIX.1-2004 requires. In glibc version 2.3.2 and earlier, these functions do not raise an invalid floating-point exception (FE_INVALID) when a domain error occurs.
COLOPHONThis page is part of release 3.27 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at //www.kernel.org/doc/man-pages/. 2008-08-10 YNF(3) | <urn:uuid:c96f0752-51bf-4d7e-ab2b-e5ea14f70a2d> | 2.625 | 859 | Documentation | Software Dev. | 66.64066 | 95,517,197 |
What's the Latest Development?
By using beams of light to stimulate portions of a monkey's brain, researchers have improved on how its brain functions, enabling the monkey to complete assigned tasks more quickly. Scientists at Massachusetts General Hospital, who used a virus to carry light-sensitive genes into the brains of two monkeys, showed they reacted about 10% faster when undergoing light stimulation. Wim Vanduffel, who headed the experiment, said that in unpublished experiments, "monkeys undergoing the technique while carrying out a more complex task improved even further. 'My hunch is that the harder the task, the more significant the effect,' he says."
What's the Big Idea?
As gene switches have been identified that work on specific areas of the brain, using beams of light to stimulate those areas has quickly evolved as a method to improve brain function. "Known as optogenetics, the method has the potential to treat conditions such as epilepsy, where the light could temporarily deactivate the brain cells that cause seizures, or Parkinson's disease, where it can activate cells that make dopamine, the neurotransmitter vital for controlling mobility that those with Parkinson's lack." Scientists continue to search for ways to target certain brain cells without disrupting healthy ones.
Photo credit: Shutterstock.com | <urn:uuid:13fba06b-0a40-4455-8d28-c5b6de2a1094> | 3.359375 | 254 | News Article | Science & Tech. | 36.265893 | 95,517,201 |
Here is a machine with four coloured lights. Can you make two lights switch on at once? Three lights? All four lights?
Can you find a way to identify times tables after they have been shifted up?
The picture illustrates the sum 1 + 2 + 3 + 4 = (4 x 5)/2. Prove the general formula for the sum of the first n natural numbers and the formula for the sum of the cubes of the first n natural. . . .
Investigate how you can work out what day of the week your birthday will be on next year, and the year after...
Here is a machine with four coloured lights. Can you develop a strategy to work out the rules controlling each light?
When number pyramids have a sequence on the bottom layer, some interesting patterns emerge...
Alison, Bernard and Charlie have been exploring sequences of odd and even numbers, which raise some intriguing questions...
In this investigation, we look at Pascal's Triangle in a slightly different way - rotated and with the top line of ones taken off.
A story for students about adding powers of integers - with a festive twist.
Let S1 = 1 , S2 = 2 + 3, S3 = 4 + 5 + 6 ,........ Calculate S17.
A 2 by 3 rectangle contains 8 squares and a 3 by 4 rectangle contains 20 squares. What size rectangle(s) contain(s) exactly 100 squares? Can you find them all?
Which of these pocket money systems would you rather have?
Watch the video to see how Charlie works out the sum. Can you adapt his method?
Charlie and Alison have been drawing patterns on coordinate grids. Can you picture where the patterns lead?
Cellular is an animation that helps you make geometric sequences composed of square cells.
Can you dissect a square into: 4, 7, 10, 13... other squares? 6, 9, 12, 15... other squares? 8, 11, 14... other squares? | <urn:uuid:8977bab9-c57f-4a33-95bb-0b08d998ae94> | 3.28125 | 406 | Content Listing | Science & Tech. | 82.094521 | 95,517,207 |
The astronomers observed the unusual system SS Leporis in the constellation of Lepus (The Hare), which contains two stars that circle around each other in 260 days. The stars are separated by only a little more than the distance between the Sun and the Earth, while the largest and coolest of the two stars extends to one quarter of this distance -- corresponding roughly to the orbit of Mercury. Because of this closeness, the hot companion has already cannibalised about half of the mass of the larger star.
These super-sharp images of the unusual vampire double star system SS Leporis were created from observations made with the VLT Interferometer at ESO’s Paranal Observatory using the PIONIER instrument. The system consists of a red giant star orbiting a hotter companion. The remarkable image sharpness -- 50 times sharper than those from the NASA/ESA Hubble Space Telescope -- not only allows the stars to be clearly separated and their orbital motion followed, but also allowed the size of the red giant to be measured more accurately than ever before. The system consists of a red giant star orbiting a hotter companion. Note that the stars have been artificially colored to match their known temperatures.
"We knew that this double star was unusual, and that material was flowing from one star to the other," says co-author Henri Boffin, from ESO. "What we found, however, is that the way in which the mass transfer most likely took place is completely different from previous models of the process. The 'bite' of the vampire star is very gentle but highly effective."
The new observations are sharp enough to show that the giant star is smaller than previously thought, making it much more difficult to explain how the red giant lost matter to its companion. The astronomers now think that, rather than streaming from one star to the other, the matter must be expelled from the giant star as a stellar wind and captured by the hotter companion.
"These observations have demonstrated the new snapshot imaging capability of the Very Large Telescope Interferometer. They pave the way for many further fascinating studies of interacting double stars," concludes co-author Jean-Philippe Berger.
The images were created from observations made with the Very Large Telescope Interferometer (VLTI) at ESOʼs Paranal Observatory using the four 1.8-metre Auxiliary Telescopes to feed light into a new instrument called PIONIER (see ann11021 - http://www.eso.org/public/announcements/ann11021/).
PIONIER, developed at LAOG/IPAG in Grenoble, France, is a visiting instrument at the Paranal Observatory. PIONIER is funded by Université Joseph Fourier, IPAG, INSU-CNRS (ASHRA-PNPS-PNP) ANR 2G-VLTI and ANR Exozodi. IPAG is part of the Grenoble Observatory (OSUG).
The VLTI engineers had to control the distance traversed by the light from the widely separated telescopes with an accuracy of about one hundredth of the thickness of a strand of human hair. Once the light reached PIONIER, it was then channelled into the heart of the instrument: a remarkable optical circuit, smaller than a credit card, that finally brought the light waves from the different telescopes together in a very precise way so that they could interfere. The resulting resolving power of the telescope array has the sharpness not of the individual 1.8-metre Auxiliary Telescopes, but that of a much bigger "virtual telescope" about 130 metres across, limited only by how far apart the telescopes can be positioned.
The resolution of the NASA/ESA Hubble Space Telescope is approximately 50 milliarcseconds whereas the resolution attainable with the VLTI is about one milliarcsecond — corresponding to the apparent size of an astronaut on the surface of the Moon, seen from Earth.
This research was presented in a paper, "An incisive look at the symbiotic star SS Leporis — Milli-arcsecond imaging with PIONIER/VLTI", by N. Blind et al. in press in the journal Astronomy & Astrophysics.
The team is composed of Nicolas Blind (UJF-Grenoble 1/CNRS-INSU, Institut de Planetologie et d'Astrophysique de Grenoble, France [IPAG]), Henri Boffin (ESO, Chile), Jean-Philippe Berger (ESO, Chile), Jean-Baptiste Le Bouquin (IPAG, France), Antoine Merand (ESO, Chile), Bernard Lazareff (IPAG, France), and Gerard Zins (IPAG, France).
ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world's largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 40-metre-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become "the world's biggest eye on the sky".
Richard Hook | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
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Most people know that monarch butterflies can’t exist without milkweed. As caterpillars, the monarchs feed on milkweed plants exclusively, absorbing the milkweed’s poisons in order to ward off birds and other predators. On their epic migration across the North American continent, the butterflies also lay their eggs on these plants, relying on the noxious taste of the leaves to keep their brood safe from grazers while simultaneously providing a buffet for the next generation when it hatches.
But milkweed plays another role in the lives of monarchs that goes largely overlooked. Some of the compounds produced in the plants’ leaves act like medicine for the butterflies, both protecting them against parasites, like the protozoan Ophryocystis elektroscirrha, and helping them cope with parasitic infections when they do occur.
Unfortunately, a new study published in the journal Ecology Letters finds that as carbon dioxide levels rise in the atmosphere, the most medicinal of those milkweed plants start to lose their juju. “Our study shows that a loss of medicinal protection caused by elevated CO2 makes the parasite more virulent,” says lead author Leslie Decker, an ecologist now at Stanford University. (The research was part of Decker's doctoral dissertation at the University of Michigan.)
In work conducted between May 2014 and May 2015, the researchers raised various species of milkweed under controlled conditions. Some of the plants grew with present-day concentrations of CO2, and some with levels like those climate scientists expect in the next 100 to 150 years. They then let monarch caterpillars go to town on these plants to see if the CO2 levels would change the way the plants helped the insects fight off infection.
The scientists found that under the futuristic CO2 conditions, all milkweed species showed dips in their concentrations of cardenolides, the steroid cocktails they produce for self-defense. But one species stood out. Monarch caterpillars that fed on Asclepias curassavica, or tropical milkweed, lost 77 percent of their tolerance to protozoan parasites. Without the normal dose of their milkweed medicine, the monarchs died a full week earlier than those that ingested tropical milkweed grown at today’s levels of CO2. This is concerning, because of the species tested, tropical milkweed proved to be far and away the most medicinal of all the plants under the current CO2 regime.
“Rising CO2 levels are likely to disrupt our natural systems in highly complex ways, including by unraveling long-established host/parasite relationships,” says Sylvia Fallon, director of NRDC’s Wildlife Conservation Project. “This would pose yet another grave threat for a species like the monarch butterfly, whose populations have already plummeted due to habitat loss and pesticide use.”
The findings are scary, especially considering that the monarchs and their massive North American migration are already under attack from all sides. Pesticides threaten the insects’ summer breeding grounds in the United States and Canada, and illegal logging is chipping away at their winter homes in the mountains of Mexico. Agriculture has already eradicated milkweed across huge swaths of the American Midwest. And even the milkweed plants available at the big box stores, which people buy to help the butterflies, can sometimes be laced with systemic poisons.
The good news is that the fate of the monarchs is far from sealed. While the new study finds that heightened CO2 levels make monarchs more vulnerable to infections, this shift in favor of the parasites may be only temporary. You see, it doesn’t help the parasites to kill their hosts; living inside adult butterflies is the only way these parasites can proliferate. Therefore, Decker says, the protozoan “evolves to only harm the monarch host as much as it has to in order to produce an optimum number of spores,” to make sure it can pass on its genes.
Right now, monarchs are able to temper the negative effects of the parasite by eating milkweed, but if that strategy slowly loses its value, the whole interspecies relationship may end up being reshuffled. Why? Because more virulent parasite strains will kill their hosts too quickly to spread their own spores, and then natural selection will likely weed them out, leaving only the parasitic strains that don’t harm the monarchs enough to kill them.
Think of it like Goldilocks—only the bears are butterflies, the porridge they eat is milkweed of varying medicinal qualities, and the little girl is an obligate neogregarine parasite that everyone agrees is trespassing.
Unfortunately, even if natural selection makes these parasites less virulent over time, the change in the compounds produced by the milkweed will also make monarchs less able to cope with the ones that do survive. “The harm inflicted by each parasite spore will increase,” Decker says, “spelling out bad news for the monarch.”
The impact of the high-carbon scenarios tested by Decker and her team highlights the importance of protecting these insects right now, if only to give them a buffer to survive what may lie ahead. “We must do everything we can to build a more stable and resilient population by planting more pollinator habitat and reducing the use of agricultural pesticides,” says Fallon. If not, one of the world’s most impressive journeys may come to an end.
onEarth provides reporting and analysis about environmental science, policy, and culture. All opinions expressed are those of the authors and do not necessarily reflect the policies or positions of NRDC. Learn more or follow us on Facebook and Twitter.
Famous for their elegant colors and transcontinental feats of migration, these beloved pollinators are also in free fall, as habitat loss and heavy use of herbicides jeopardize their future.
New research shows a certain type of milkweed can harm monarchs—but we still need to give these butterflies something to snack on.
Be a good neighbor to struggling pollinators by turning your backyard into a welcome pit stop.
Projects across the Midwest are trying to bring milkweed and nectar-filled flowers back to the landscape.
The Moth Migration Project gathers ink-and-paper insects from all over the world in an immersive crowd-sourced installation.
You may have never heard of them, but there are hundreds around the world. Find out what makes this specific type of reserve so special.
Forests are among our greatest allies in the global warming fight. Let’s protect them so they can protect us. | <urn:uuid:eba25b30-0990-4991-ba57-d7ec602de6e7> | 3.890625 | 1,351 | News Article | Science & Tech. | 36.334511 | 95,517,211 |
This wind tunnel design pdf a good article. Follow the link for more information. Atmospheric wind shear is normally described as either vertical or horizontal wind shear. Vertical wind shear is a change in wind speed or direction with change in altitude.
Horizontal wind shear is a change in wind speed with change in lateral position for a given altitude. Wind shear has significant effects on control of an aircraft effect, and it has been a sole or contributing cause of many aircraft accidents. Wind shear is sometimes experienced by pedestrians at ground level when walking across a plaza towards a tower block and suddenly encountering a strong wind stream that is flowing around the base of the tower. Sound movement through the atmosphere is affected by wind shear, which can bend the wave front, causing sounds to be heard where they normally would not, or vice versa. Wind shear refers to the variation of wind over either horizontal or vertical distances.
Vertical speed changes greater than 4. Wind shear is also a key factor in the creation of severe thunderstorms. Note the downward motion of the air until it hits ground level, then spreads outward in all directions. The wind regime in a microburst is completely opposite to a tornado.
Vertical wind shear above warm fronts is more of an aviation concern than near and behind cold fronts due to their greater duration. When a nocturnal low-level jet forms overnight above the Earth’s surface ahead of a cold front, significant low level vertical wind shear can develop near the lower portion of the low level jet. This is also known as nonconvective wind shear since it is not due to nearby thunderstorms. The change in wind can be 90 degrees in direction and 40 kt in speed. It tends to be strongest towards sunrise. | <urn:uuid:8a89921a-5a02-4129-8f0a-d45c850c3408> | 4.28125 | 361 | Knowledge Article | Science & Tech. | 54.218725 | 95,517,214 |
Which things I need to know to study relativity theory? And any good book to study it?
Einstein's original introductory work is available free on project Guttenburg. Steve
can you give me the link?
Link at top now
Is it in German ?
One great book that influenced me a lot has been Carl Sagan's Cosmos. You could also search for the works of Michio Kaku, Stephen Hawkings or Neil deGrasse Tyson.
If you just want a basic knowledge of physics, believe it or not a good Science Fiction like Star trek and other Science Fiction books by authors with physics backgrounds. They are more entertaining than a stuffy text book. If you want serious theatrical physics kelseymh has your answer. And if you want something between the two, watch Big Bang Theory, surprisingly they push authors that write physics books for the layman. I am not pushing SiFi because I am a writer surprisingly there are very few physics mistakes that get past our fans. Joe
If all you want is special relativity (comparing viewpoints for observers travelling at different speeds), then you need high school algebra. If you want to learn about general relativity (gravity, acceleration, curved spacetime, cosmology), then you will need to complete college level courses in physics and calculus, including how to solve differential equations.
What level are you starting from, and what level are you aiming at? | <urn:uuid:80ba38e0-a257-429f-ab10-0ee798cc5723> | 2.640625 | 288 | Q&A Forum | Science & Tech. | 53.254846 | 95,517,217 |
Presenting a new method to improve the detection of micro-seismic events
- 11 Downloads
Seismic events such as earthquakes are one of the most important issues in the field of geology. Meanwhile, less attention has been paid to micro-seismic events, despite the high number of earthquakes. Earthquakes, regardless of their size, affect human life; therefore, their detection and management is considered an important issue. For this purpose, experts developed seismic arrays as a system of linked seismometers. These systems equipped with sensors and seismographs are able to receive a range of waves from the earth, which are then sent to the central seismic station for analysis. So far, many tools and methods have been devised to analyze seismic data. However, the dominant method in most seismic mechanisms is trigger function, based on STA/LTA (short-time-average through long-time-average trigger). These mechanisms have considerable threshold in terms of earthquake range, so many micro-events are ignored as noise. Generally, in this field of geology, computer science techniques have been used to detect and classify these events. Statistical methods such as kurtosis, variance, and skewness can be applied to understand the changes in the signal curves of geophones in a seismic event, thereby helping in the initial detection of fuzzy features. According to the last 3 years’ reports of global data mining agencies such as Rexer, KDnugget, and Gartner, Rapid Miner is one of the most popular tools for data mining in recent years. Furthermore, these institutions considered artificial neural networks, especially multilayer perceptron (MLP) and base radial function (RBF), to be among the most successful algorithms for detection and classification of stream data. In this research, the recorded data from several seismic experiments has been classified by a hybrid model. Hence, the present study was aimed to enhance the authenticity of data based on the application of effective variables. This was undertaken through use of a fuzzy method and an integrated neural network algorithm, involving MLP perceptron and radial network of RBF in the form of a collective learning system, in order to identify seismic events on a small scale. Based on the results, in comparison to basic methods, the proposed method significantly improved using the actual error and root-mean-square error (RMSE) criteria.
KeywordsMicro-seismic events Neural network Fuzzy logic Seismic event detection MLP RBF
Is not available.
Saeed Ghorbani (corresponding author) designed the study, developed the methodology, carried out the tests, collected the data, performed the analysis, and wrote the manuscript.
Morteza Barari designed the proposed model structure and has offered the MLP and RBF algorithms (neural network).
Mojtaba Hoseini checked the performance correctness of tools and methods.
Compliance with ethical standards
The authors declare that they have no competing interests.
- Annual Gartner report (2017). Gartner magic quadrants for data science platforms compared, 2017 vs 2016, https://www.gartner.com/technology/home.
- Annual KDnugget report (2015). https://www.kdnuggets.com/.
- Haykin, S. (1998). Neural networks: a comprehensive foundation (2 ed.), Prentice Hall, ISBN 0-13-273350-1.Google Scholar
- Kurban, T., & Beşdok, E. (2009). A comparison of rbf neural network training algorithms for inertial sensor based terrain classification, Geomatics Engineering, Engineering Faculty, Erciyes University, Turkey.Google Scholar
- Rumelhart, D. E., & McClelland, J. L. (1986). Parallel Distributed Processing: Explorations in the Microstructure of Cognition (Vol. 1). Cambridge: MIT Press.Google Scholar
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- Wyss, M., Pacchiani, F., Deschamps, A., & Patau, G. (2008). Mean magnitude variations of earthquakes as a function of depth: different crustal stress distribution depending on tectonic setting. Geophysical Research Letters, 35. https://doi.org/10.1029/2007GL031057.
- Zamani, A., & Agh-Atabai, M. (2011). Multifractal analysis of the spatial distribution of earthquake epicenters in the Zagros and Alborz-Kopeh Dagh regions of Iran. Journal Science and Technology, A1, 39–51.Google Scholar | <urn:uuid:fdd9815a-09a6-4821-a9e7-8a2d01dacb06> | 2.765625 | 1,028 | Academic Writing | Science & Tech. | 43.305421 | 95,517,222 |
Pollution from the eruption will drift to East and Southeast Iceland today, from Fáskrúðsfjörður in the north to the southeastern corner of Vatnajökull and the town of Höfn in the south.
Ten earthquakes were automatically detected in Bárðarbunga and another ten in the dike beneath northern Dyngjujökull glacier between midnight and 6:48 am this morning. This is a similar rate to what was observed yesterday morning.
The sulfur dioxide (SO2) emitted from the Holuhraun eruption has reached up to 60,000 tons per day and averaged close to 20,000 tons since it began. For comparison, all the SO2 pollution in Europe, from industries, energy production, traffic and house heating, etc., amounts to 14,000 tons per...
The sulfur dioxide (SO2) pollution from the Holuhraun eruption has spread to Germany, Spiegel Online reports. With wind blowing from the northwest, the pollution is being felt further to the east than previously.
The Icelandic Met Office’s forecast for today indicates that the sulfur dioxide (SO2) pollution the Holuhraun eruption will spread to a large area of North and Northeast Iceland, including the towns of Akureyri and Húsavík (click here for a map of the affected area).
Three earthquakes above magnitude 3.0 have been measured around Bárðarbunga volcano under Vatnajökull glacier since midnight, the strongest of which was of magnitude 5.2. Pollution from the Holuhraun eruption site will likely be carried across Egilsstaðir and the East Fjords today.
The lava from the Holuhraun eruption flows at the same rate as yesterday, mostly around the center of the lava field, which is now around 37 square km (14.3 square miles).
Today, pollution from the eruption in Holuhraun is mostly expected to drift to the northeast of the eruption site, although it may temporarily move towards the east, according to the Icelandic Met Office’s forecast. On Saturday, the pollution reached Reykjavík.
The Civil Protection Department in Iceland stresses that not respecting that the eruption site around Holuhraun is closed to the public may be life-threatening. Birds that died of poisoning have been found at the eruption site.
The volcanic eruption in Holuhraun continues at a similar rate and the subsidence of the Bárðarbunga caldera continues. On Saturday residents in Reykjavík noticed a smell of sulfur and there was a haze over the mountains in the east.
Sulfur dioxide (SO2) gas is expected to pollute the air in North Iceland from Strandir to Eyjafjörður, the north-central highlands and East Iceland from Egilsstaðir to Höfn. While the eruption in Holuhraun continues, fewer and smaller earthquakes were recorded by Bárðarbunga.
Farmers in East and Northeast Iceland, the regions that have suffered the most sulfur dioxide (SO2) pollution from the Holuhraun eruption, are concerned about the wellbeing of their free-roaming sheep.
The Icelandic Met Office has started publishing maps on their website with forecasts of the spread of the pollution caused by toxic sulfur dioxide (SO2) gas coming from the Holuhraun eruption, on a daily basis.
Icelandic tourism companies are being approached by prospective tourists from abroad, who are interested in viewing the eruption in Holuhraun up close. A meeting was held to discuss the possibility yesterday.
Considerably strong earthquakes hit Bárðarbunga volcano in Vatnajökull glacier yesterday evening, of magnitude 4.8 at 8:20 pm and of magnitude 5.4 at 9:34 pm.
Seismic activity is continuing in the eruption area at Bárðarbunga and Holuhraun with about 50 earthquakes occurring between midnight and 6:45 am this morning.
The Department of Civil Protection has advised all people in the village of Kópasker, Northeast Iceland, and surrounding areas to stay indoors, close the windows and turn up the radiators due to high levels of sulfur dioxide pollution from the eruption.
Sulfur dioxide (SO2) pollution from the eruption in Holuhraun spread to Northeast Iceland yesterday. | <urn:uuid:7cd03512-d460-4dc8-bf6f-9a83304dc0bc> | 2.78125 | 922 | News Article | Science & Tech. | 43.067874 | 95,517,242 |
"The discovery overturns a long-standing belief about how and when most of the solar particles penetrate Earth's magnetic field, and could be used to predict when solar storms will be severe.
Based on these results, we expect more severe storms during the upcoming solar cycle," said Vassilis Angelopoulos of the University of California, Los Angeles, Principal Investigator for NASA's THEMIS mission (Time History of Events and Macroscale Interactions during Substorms). THEMIS was used to discover the size of the leak.
Earth's magnetic field acts as a shield against the bombardment of particles continuously streaming from the sun. Because the solar particles (ions and electrons) are electrically charged, they feel magnetic forces and most are deflected by our planet's magnetic field. However, our magnetic field is a leaky shield and the number of particles breaching this shield depends on the orientation of the sun's magnetic field. It had been thought that when the sun's magnetic field is aligned with that of the Earth, the door is shut and that few if any solar particles enter Earth's magnetic shield. The door was thought to open up when the solar magnetic field direction points opposite to Earth's field, leading to more solar particles inside the shield.
Surprisingly, recent observations by the THEMIS spacecraft fleet demonstrate that the opposite is true. "Twenty times more solar particles cross the Earth's leaky magnetic shield when the sun's magnetic field is aligned with that of the Earth compared to when the two magnetic fields are oppositely directed," said Marit Oieroset of the University of California, Berkeley, lead author of one of two papers on this research, published May 2008 in Geophysical Research Letters.
Researchers have long suspected that this "closed door" entry mechanism might exist, but didn't know how important it was. "It's as if people knew there was a crack in a levy, but they did not know how much flooding it caused," said Oieroset.
Previous spacecraft could only sample a small part of this enormous layer of solar particles inside the Earth's magnetic shield, but the five spacecraft in the THEMIS fleet spanned the entire rapidly-growing layer to give definitive measurements.
While the THEMIS researchers discovered the size of the leak, they didn't know its location(s). This was discovered by Wenhui Li of the University of New Hampshire, Durham, N.H., and his team. They used a computer simulation to discover where two holes frequently develop in Earth's magnetic field, one at high latitude over the Northern hemisphere, and one at high latitude over the Southern hemisphere. The holes form over the daylit side of Earth, on the side of the magnetic shield facing the sun.
The simulation also showed how the leaks develop. As solar particles flow out from the sun, they carry solar magnetic fields past our planet. Li's team realized that the solar magnetic field drapes against Earth's field as it passes by. Even though the two fields point in the same direction at equatorial latitudes, they point in opposite directions at high latitudes, When compression forces the opposite fields together, they link up with each other in a process called magnetic reconnection. This process tears the two holes in Earth's magnetic field and appends the section of the solar field between the two holes to Earth's field, carrying the solar particles on this section into the magnetosphere, according to Li's team. "We've found if the door is closed, the sun tears down a wall. The crack is huge – about four times wider than Earth and more then seven Earth diameters long," said Li, whose paper will be published in an upcoming article of the Journal of Geophysical Research.
Solar particles by themselves don't cause severe space weather, but they get energized when the solar magnetic field becomes oppositely-directed to Earth's and reconnects in a different way. The energized particles then cause magnetic storms that can overload power lines with excess current, causing widespread blackouts. The particles also can cause radiation storms that present hazards to spacecraft in high orbits and astronauts passing through the storms on the way to the moon or other destinations in the solar system. "The more particles, the more severe the storm," said Joachim "Jimmy" Raeder of the University of New Hampshire, a co-author of Li's paper. "If the solar field has been aligned with the Earth's for a while, we now know Earth's field is heavily loaded with solar particles and primed for a strong storm. This discovery gives us a basic predictive capability for the severity of solar storms, similar to a hurricane forecaster's realization that warmer oceans set the stage for more intense hurricanes. In fact, we expect stronger storms in the upcoming solar cycle. The sun's magnetic field changes direction every cycle, and due to its new orientation in the upcoming cycle, we expect the clouds of particles ejected from the sun will have a field which is at first aligned with Earth, then becomes opposite as the cloud passes by."
Cynthia M. O'Carroll | EurekAlert!
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
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Research provides measurements for scientists searching for water in solar system
Water is thought to be embedded in the moon’s rocks or, if cold enough, “stuck” on their surfaces. It’s predominantly found at the poles. But scientists probably won’t find it intact on the sunlit side.
New research at the Georgia Institute of Technology indicates that ultraviolet photons emitted by the sun likely cause H2O molecules to either quickly desorb or break apart. The fragments of water may remain on the lunar surface, but the presence of useful amounts of water on the sunward side is not likely.
The Georgia Tech team built an ultra-high vacuum system that simulates conditions in space, then performed the first-ever reported measurement of the water photodesorption cross section from an actual lunar sample. The machine zapped a small piece of the moon with ultraviolet (157 nm) photons to create excited states and watched what happened to the water molecules. They either came off with a cross section of ~ 6 x 10−19 cm2 or broke apart with a cross section of ~ 5 x 10−19 cm2.. According to the team’s measurements, approximately one in every 1,000 molecules leave the lunar surface simply due to absorption of UV light.
Georgia Tech’s cross section values can now be used by scientists attempting to find water throughout the solar system and beyond.
“The cross section is an important number planetary scientists, astrochemists and the astrophysics community need for models regarding the fate of water on comets, moons, asteroids, other airless bodies and interstellar grains,” said Thomas Orlando, the Georgia Tech professor who led the study.
The number is relatively large, which establishes that solar UV photons are likely removing water from the moon’s surface. This research, which was carried out primarily by former Georgia Tech Ph.D. student Alice DeSimone, indicates the cross sections increase even more with decreasing water coverage. That’s why it’s not likely that water remains intact as H2O on the sunny side of the moon. Orlando compares it to sitting outside on a summer day.
“If a lot of sunlight is hitting me, the probability of me getting sunburned is pretty high,” said Orlando, a professor in the School of Chemistry and Biochemistry and School of Physics. “It’s similar on the moon. There’s a fixed solar flux of energetic photons that hit the sunlit surface, and there’s a pretty good probability they remove water or damage the molecules.“
The result, according to Orlando, is the release of molecules such as H2O, H2 and OH as well as the atomic fragments H and O. The research is published in two companion articles in the Journal of Geophysical Research: Planets. The first discusses the water photodesorption. The second paper details the photodissociation of water and the O(3PJ) formation on a lunar impact melt breccia.
Orlando is the associate director of Georgia Tech’s Center for Space Technology and Research (C-STAR). C-STAR is an interdisciplinary research center that serves to organize, integrate and facilitate the impact of Georgia Tech's space science and space technology research activities. The center brings together a wide range of Georgia Tech faculty, active in space science and space technology research, and functions as the Institute’s focal point for growth of the space industry in the state of Georgia.
This material is based upon work supported by NASA under award number NNX11AP13G. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NASA.
Jason Maderer | 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 | Power and Electrical Engineering | <urn:uuid:ff4f0422-d090-41df-a0d7-a24ea6304784> | 3.796875 | 1,413 | Content Listing | Science & Tech. | 42.698105 | 95,517,259 |
A team led by the University of Colorado at Boulder and the University of Milan has discovered some unexpected forms of liquid crystals of ultrashort DNA molecules immersed in water, providing a new scenario for a key step in the emergence of life on Earth.
CU-Boulder physics Professor Noel Clark said the team found that surprisingly short segments of DNA, life’s molecular carrier of genetic information, could assemble into several distinct liquid crystal phases that “self-orient” parallel to one another and stack into columns when placed in a water solution. Life is widely believed to have emerged as segments of DNA- or RNA-like molecules in a prebiotic “soup” solution of ancient organic molecules.
A paper on the subject was published in the Nov. 23 issue of Science. The paper was authored by Clark, Michi Nakata and Christopher Jones from CU-Boulder, Giuliano Zanchetta and Tommaso Bellini of the University of Milan, Brandon Chapman and Ronald Pindak of Brookhaven National Laboratory and Julie Cross of Argonne National Laboratory. Nakata died in September 2006.
Since the formation of molecular chains as uniform as DNA by random chemistry is essentially impossible, Clark said, scientists have been seeking effective ways for simple molecules to spontaneously self-select, “chain-up” and self-replicate. The new study shows that in a mixture of tiny fragments of DNA, those molecules capable of forming liquid crystals selectively condense into droplets in which conditions are favorable for them to be chemically linked into longer molecules with enhanced liquid crystal-forming tendencies, he said.
“We found that even tiny fragments of double helix DNA can spontaneously self-assemble into columns that contain many molecules,” Clark said. “Our vision is that from the collection of ancient molecules, short RNA pieces or some structurally related precursor emerged as the molecular fragments most capable of condensing into liquid crystal droplets, selectively developing into long molecules.”
Liquid crystals -- organic materials related to soap that exhibit both solid and liquid properties -- are commonly used for information displays in computers, flat-panel televisions, cell phones, calculators and watches. Most liquid crystal phase molecules are rod-shaped and have the ability to spontaneously form large domains of a common orientation, which makes them particularly sensitive to stimuli like changes in temperature or applied voltage.
RNA and DNA are chain-like polymers with side groups known as nucleotides, or bases, that selectively adhere only to specific bases on a second chain. Matching, or complementary base sequences enable the chains to pair up and form the widely recognized double helix structure. Genetic information is encoded in sequences of thousands to millions of bases along the chains, which can be microns to millimeters in length.
Such DNA polynucleotides had previously been shown to organize into liquid crystal phases in which the chains spontaneously oriented parallel to each other, he said. Researchers understand the liquid crystal organization to be a result of DNA’s elongated molecular shape, making parallel alignment easier, much like spaghetti thrown in a box and shaken would be prone to line up in parallel, Clark said.
The CU-Boulder and University of Milan team began a series of experiments to see how short the DNA segments could be and still show liquid crystal ordering, said Clark. The team found that even a DNA segment as short as six bases, when paired with a complementary segment that together measured just two nanometers long and two nanometers in diameter, could still assemble itself into the liquid crystal phases, in spite of having almost no elongation in shape.
Structural analysis of the liquid crystal phases showed that they appeared because such short DNA duplex pairs were able to stick together “end-to-end,” forming rod-shaped aggregates that could then behave like much longer segments of DNA. The sticking was a result of small, oily patches found on the ends of the short DNA segments that help them adhere to each other in a reversible way -- much like magnetic buttons -- as they expelled water in between them, Clark said.
A key characterization technique employed was X-ray microbeam diffraction combined with in-situ optical microscopy, carried out with researchers from Argonne and Brookhaven National Laboratories. The team using a machine called the Argonne Advanced Photon Source synchrotron that enabled probing of the “nano DNA” molecular organization in single liquid crystal orientation domains only a few microns in size. The experiments provided direct evidence for the columnar stacking of the nano DNA pieces in a fluid liquid crystal phase.
“The key observation with respect to early life is that this aggregation of nano DNA strands is possible only if they form duplexes,” Clark said. “In a sample of chains in which the bases don’t match and the chains can’t form helical duplexes, we did not observe liquid crystal ordering.”
Subsequent tests by the team involved mixed solutions of complementary and noncomplementary DNA segments, said Clark. The results indicated that essentially all of the complementary DNA bits condensed out in the form of liquid crystal droplets, physically separating them from the noncomplementary DNA segments.
“We found this to be a remarkable result,” Clark said. “It means that small molecules with the ability to pair up the right way can seek each other out and collect together into drops that are internally self-organized to facilitate the growth of larger pairable molecules.
“In essence, the liquid crystal phase condensation selects the appropriate molecular components, and with the right chemistry would evolve larger molecules tuned to stabilize the liquid crystal phase. If this is correct, the linear polymer shape of DNA itself is a vestige of formation by liquid crystal order.”
Source: University of Colorado at Boulder
Explore further: Scientists decipher the structure, key features of a critical immune-surveillance protein in humans | <urn:uuid:27027cf6-88a5-4e0f-a9c0-52a995ca2512> | 3.453125 | 1,220 | News Article | Science & Tech. | 20.315183 | 95,517,276 |
Miniature glasses have proved that mantises use 3D vision - providing a new model to improve visual perception in robots.
Most knowledge about 3D vision has come from vertebrates, however, a team from Newcastle University, UK publishing today in Scientific Reports, confirm that the praying mantis, an invertebrate, does indeed use stereopsis or 3D perception for hunting.
In a specially-designed insect cinema, they have shown that it needs to be 'old school' 3D glasses for tests to work on mantises. While in humans that would be with red and blue lenses, red light is poorly visible to mantises so they have custom-made glasses with one blue and one green lens!
Better understanding of 3D vision
3D vision in mantises was originally shown in the 1980s by Samuel Rossel, but his work used prisms and occluders which meant that only a very limited set of images could be shown. The Newcastle University team has developed 3D glasses suitable for insects which means they can show the insects any images they want, opening up new avenues of research.
Study leader, Jenny Read, Professor of Vision Science said: "Despite their minute brains, mantises are sophisticated visual hunters which can capture prey with terrifying efficiency. We can learn a lot by studying how they perceive the world.
"Better understanding of their simpler processing systems helps us understand how 3D vision evolved, and could lead to possible new algorithms for 3D depth perception in computers."
In the experiments, mantises fitted with tiny glasses attached with beeswax were shown short videos of simulated bugs moving around a computer screen. The mantises didn't try to catch the bugs when they were in 2D. But when the bugs were shown in 3D, apparently floating in front of the screen, the mantises struck out at them. This shows that mantises do indeed use 3D vision.
Old-school 3D glasses
Initial testing of the most widely-used contemporary 3D technology used for humans - using circular polarization to separate the two eyes' images - didn't work because the insects were so close to the screen that the glasses failed to separate the two eyes' images correctly.
Dr Vivek Nityananda, sensory biologist at Newcastle University and part of the research team continues: "When this system failed we looked at the old-style 3D glasses with red and blue lenses. Since red light is poorly visible to mantises, we used green and blue glasses and an LED monitor with unusually narrow output in the green and blue wavelength.
"We definitively demonstrated 3D vision or stereopsis in mantises and also showed that this technique can be effectively used to deliver virtual 3D stimuli to insects."
The Newcastle University team will now continue the research examining the algorithms used for depth perception in insects to better understand how human vision evolved and to develop new ways of adding 3D technology to computers and robots.
Reference: Insect stereopsis demonstrated using a 3D insect cinema. Vivek Nityananda, Ghaith Tarawneh, Ronny Rosner, Judith Nicolas, Stuart Crichton & Jenny Read. Scientific Reports 6, Article number: 18718 http://www.
Karen Bidewell | EurekAlert!
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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18.07.2018 | Health and Medicine | <urn:uuid:f2635c10-b655-4b9b-80db-d4dcc87fc8ec> | 3.59375 | 1,291 | Content Listing | Science & Tech. | 42.133283 | 95,517,279 |
New research published in Environmental Toxicology and Chemistry addresses the effects of two broad-spectrum systemic insecticides, fipornil and imidacloprid, on honeybees.
These insecticides are widely used in agriculture, and the authors conclude that fipronil and imidacloprid are inhibitors of mitochondrial bioenergetics, resulting in depleted cell energy. This action can explain the toxicity of these compounds for honeybees.
Scientists are urgently trying to determine the causes of colony collapse disorder and the alarming population declines of honeybees. The cross-pollination services they provide are required by approximately 80 percent of all flowering plants, and 1/3 of all agricultural food production directly depends on bee pollination. As a result, there has been a flurry of research on honeybee parasitic mite infestations, viral diseases, and the direct and indirect impacts of pesticides.
The effects of pyrazoles (e.g., fipronil) and neonicotinoids (e.g., imidacloprid) on the nervous system are fairly well documented. Daniel Nicodemo, professor of ecology and beekeeping at the Universidade Estadual Paulista in Dracena, Brazil, and lead author of the study states, "These insecticides affect the nervous system of pest and beneficial insects, often killing them.
Sublethal effects related to insect behavior have been described in other studies; even a few nanograms of active ingredient disturbed the sense of taste, olfactory learning and motor activity of the bees." A key characteristic of colony collapse disorder is the incapacity of the honeybees to return to their hives, and these disruptions have a direct impact on that ability.
In this study, Nicodemo et al. looked at the effects of fipronil and imidacloprid on the bioenergetics functioning of mitochondria isolated from the heads and thoraces of Africanized honeybees. Mitochondria are the power plants of a cell, generating most of a cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy.
Honeybee flight muscles are strongly dependent on high levels of oxygen consumption and energy metabolism. Mitochondrial oxidative phosphorylation drives ATP synthesis, which is required to contract the muscles during flight. "If something goes wrong, the energy production is impaired," explains Nicodemo. "Similar to a plane, honeybees require clean fuel in order to fly."
Both fipronil and imidacloprid negatively affected the mitochondrial bioenergetics of the head and thorax of the honeybees. While at sublethal levels, insecticide damage may not be evident, even such low level exposure clearly contributes to the inability of a honeybee to forage and return to the hive, which could result in declining bee populations.
Jennifer Lynch | Eurek Alert!
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine | <urn:uuid:99ca80ee-a71d-41a3-9cb2-1563a8c6f1f9> | 3.015625 | 1,220 | Content Listing | Science & Tech. | 29.204414 | 95,517,280 |
The Atlantic puffin (Fratercula arctica), is one of the most widely recognised seabird species in the North Atlantic Ocean. Whilst the identity of the puffin is celebrated amongst nature lovers, not all is well for these charismatic seabirds.
ZSL is working with the Centre for Marine and Renewable Energy Research (MaREI) to study the puffins to learn more about their key foraging areas and behaviour.
Changing climate causing sea temperature rises and changes in prey distribution, are badly affecting the ability of the puffin to forage successfully. Looking within colonies, puffins are also susceptible to predation from invasive species such as rats. In 2015, the Atlantic puffin was listed as vulnerable on the IUCN Red List of Threatened Species, and Endangered within Europe.
Little Saltee is a small but stunning island on the south-east coast of Ireland that has a small population of puffins. The location of the island, close to the Celtic Sea front, and the ease of access to the island for researchers makes this a prime location for studying puffins.
This summer, a collaborative project between ZSL and The Centre for Marine and Renewable Energy Research (MaREI) has been undertaking GPS tracking studies to assess the foraging ecology of puffins. Tracking studies are a versatile tool in the assessment of animal populations, and provide a key insight into the lives of individual animals. Using GPS tracking, it is possible to find the home range and identify key foraging areas for a population, as well as developing an understanding of the fine scale behaviours that animals undertake in an effort to locate their food.
GPS and depth logging tags weighing just 9 grams were successfully deployed on eleven puffins. The resulting data showed that individual birds travel up to 40km from the colony and dive to 8-12m deep, capturing sandeels to bring back to the colony and feed their chicks.
One puffin had also captured a small octopus! Events and projects such as these are exciting moments for us as researchers, giving us a glimpse in to the ecology of key species of conservation concern.
The Atlantic puffin population is decreasing globally, with a predicted drop of between 50-79% by 2065. Studies such as these provide information that can be instrumental in identifying important areas at sea for foraging, and will hopefully lead to effective conservation measures for this iconic seabird.
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A blog for lovers of ZSL London Zoo, bringing you extraordinary animal facts and exclusive access to the world's oldest scientific zoo.
Do you love wildlife? Discover more about our amazing animals at the UK's biggest zoo!
We're working around the world to conserve animals and their habitats, find out more about our latest achievements.
From the field to the lab, catch up with the scientists on the cutting edge of conservation biology at ZSL’s Institute of Zoology.
A day in Discovery and Learning at ZSL is never dull! The team tell us all about the exciting sessions for school children, as well as work further afield.
Ever wondered what a typical day as a zookeeper looks like, or what it's like to be a videographer at ZSL? Now you can find out!
Every month, one of the pieces held in ZSL’s Library and at ZSL Whipsnade Zoo will feature here as Artefact of the Month.
Read extracts from ZSL's award winning members' magazine, Wild About.
Get updates on our latest ranges, be the first to hear about special offers, and find the perfect gift for animal lovers!
The Chagos archipelago is a rare haven for marine biodiversity. Hear from the team about our projects to protect the environments in the British Indian Ocean Territory (BIOT).
ZSL Institute of Zoology researchers are embarking on an exciting fieldwork expedition to Nelson’s Island in the Chagos Archipelago. Throughout the month, the team will share their research and experiences on an uninhabited tropical island!
ZSL works across Asia, from the famous national parks of Nepal to marine protected areas in the Philippines. Read the latest updates on our conservation.
An Open Access journal for research at the interface of remote sensing, ecology and conservation. | <urn:uuid:95cd6cff-313a-4844-a34b-42868a6cca55> | 4 | 880 | Content Listing | Science & Tech. | 41.711152 | 95,517,305 |
link to tutorial
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Process Record and Replay
Process record and replay is a gdb feature first appearing in the gdb 7.0 release (September 2009).
For supported architectures and OS/ABIs, this feature allows the user to record the execution of a program being debugged by gdb, and then "play back" the recorded execution, deterministicly and repeatedly if desired.
Process record and replay also supports gdb's reverse debugging commands, so that during replay it is possible to debug the program backward as well as forward.
Process record and replay now has a tutorial.
Process record and replay is currently supported for the following gdb targets:
- moxie-elf / moxie-linux
How it works
Process record and replay works by logging the execution of each machine instruction in the child process (the program being debugged), together with each corresponding change in machine state (the values of memory and registers). By successively "undoing" each change in machine state, in reverse order, it is possible to revert the state of the program to an arbitrary point earlier in the execution. Then, by "redoing" the changes in the original order, the program state can be moved forward again.
The following gdb commands are defined for process record / replay:
- "target record" (or simply "record", for short)
Start process record/replay (ie. start recording the subsequent execution of the child process). You must start debugging the program (with the "run" command) before using this command to start recording. You can start recording at any point after the child process has been started (eg. at a breakpoint).
- "record stop"
Stop process record/replay (ie. cease recording the program execution), and discard any existing execution log. The child process is not terminated, and you may continue to debug it normally.
- "record delete"
Discard the existing execution log, and begin recording a new log.
- "set record insn-number-max"
Set the maximum number of instruction executions that will be recorded (ie. the size of the process record log buffer). Zero means unlimited. Default is 200,000.
- "set record stop-at-limit"
Controls the behavior when the buffer becomes full. If "on", gdb will stop and ask the user what to do. If "off", the buffer acts as a circular buffer, deleting the oldest records to make room for new ones. Default is "on".
- "info record insn-number"
Show the current number of instructions in the record/replay buffer.
To run the gdb reverse-debugging tests with process record and replay, you need a board description file "precord.exp", which should look like this:
# Testing programs using process record/replay (precord) load_base_board_description "unix" set_board_info gdb,can_reverse 1 set_board_info gdb,use_precord 1
Then the "make check" command will look like this:
make check RUNTESTFLAGS="--target_board precord (test file or files)
At the time of this writing, the reverse debugging tests include:
To Do List
See the more extensive WishList here.
See the old to do list (it include some links of patch) here.
- Improve support for intel architectures. There is a patch awaiting approval that will add
support for the basic floating point instructions. We would like to also add support for the more modern math coprocessors (mmx etc.)
- Add support for more processor architectures (mips, arm etc.)
- Add support for more os/abis (currently only linux is supported).
- Improve support for memory free (sys_brk).
- Improve support for multi-thread and multi-process record/replay.
- Improve performance (speed and memory usage).
- Save execution log to a file, and restore it later for replay.
- Add more test cases to the testsuite.
- Improve documentation. The following is a quote from Eli Zaretskii, the gdb docs maintainer:
What I think is still missing from the manual is a few sentences that would explain when this target is useful. Can you provide such warstories? I will then add them to the manual. No, I mean description of when this target is useful in real life, and how you will use it. In other words, put yourself in a place of someone who reads the manual about the record/replay target and asks him/herself "why should I care about this new feature?" Then try to answer that question. And try to answer it so that the reader will wonder how could she ever get by without this feature before.
There is a contribution from Marc Khouzam at http://sourceware.org/ml/gdb-patches/2009-05/msg00058.html. | <urn:uuid:b18a75f9-8400-4ac7-b379-889cd72c156e> | 2.84375 | 1,085 | Documentation | Software Dev. | 53.564377 | 95,517,321 |
Students analyse different climate zones and their characteristics including temperature and rainfall. They use a climate zone map to identify different climate zones within Australia. Students read a simple column and line graph to record information about weather patterns. The geographical tools used in this lesson are mapping, visual representation and graphs and statistics.
Are all climate types the same?
ACHASSI053, ACHASSI058, ACHASSK068
VCGGC074, VCGGC076, VCGGK081 | <urn:uuid:1df82a8e-627d-4671-917d-27937f652501> | 3.78125 | 105 | Content Listing | Science & Tech. | 22.955182 | 95,517,325 |
Astronomers call this an HII (pronounced "H-two") region, and this particularly stunning example stretches out across space for over 200 light-years. The name stems from the fact that it is the 29th entry in the catalogue published by Australian astronomer Colin Stanley Gum in 1955.
Embedded deep within the huge, nebulous expanse of Gum 29, the relatively little known cluster of Westerlund 2 is clearly seen in the centre of this image. The latest measurements indicate that it lies at a distance of some 26 000 light-years from Earth, placing it towards the outside edge of the Carina spiral arm of the Milky Way. The cluster's distance has been the subject of intense scrutiny in the past, as it is one of the parameters needed to understand this intriguing object. Westerlund 2 is very young too, with an age of only 1—2 million years.
Previous observations have shown that two stars to the bottom right of the cluster are true leviathans. Together they form what is known as a double system. The two stars have masses of 82 and 83 times that of our Sun and rotate around each other in approximately 3.7 days. They are amongst the most massive stars known to astronomers.
Detailed observations of this intriguing pair have also shown that they are both Wolf-Rayet stars. These are massive stars nearing the end of their lives, expelling vast quantities of material as their final swansong. Observations made in X-rays have subsequently shown that streams of material from each star continually collide, creating a blaze of X-ray radiation.
The image was obtained with the Wide Field Imager (WFI) camera attached to the 2.2-m Max-Planck/ESO telescope at ESO's La Silla observatory site in Chile. Located at an altitude of 2400 metres in the arid Atacama Desert, this observatory sits under some of the clearest and darkest skies on Earth. The WFI excels at studying the farthest depths of the Universe from this unrivalled vantage point.
Henri Boffin | alfa
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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20.07.2018 | Materials Sciences | <urn:uuid:e75c9a9a-fa00-4f16-b838-fec6247cdbc3> | 3.078125 | 1,005 | Content Listing | Science & Tech. | 45.580774 | 95,517,348 |
Introduction and Motivation
Part of the Undergraduate Texts in Mathematics book series (UTM)
In control theory, one is interested in governing the state of a system by using controls. The best way to understand these three concepts is through examples.
KeywordsControl Problem Optimal Control Problem Target State Optimal Control Theory Successful Control
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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New Record Structure Defies Fundamental Tenet of Modern Cosmology
December 3, 2013
A structure over twice as large as the previous record holder puts immense strain on theories of the universe.
Cosmic Lottery: How Many Habitable Planets?
November 23, 2013
News media ran with a suggestion that one in five stars has a habitable planet, but they didn't read the fine print.
Lunar Dust Problem Re-opened
November 21, 2013
Long-lost Apollo data on lunar dust accumulation has been found, showing a tenfold increase over previous estimates. What does that imply about the age of the moon?
Surprising Things Science Didn't Know
November 17, 2013
Scientists presume to speak with confidence about the origin of the universe and billions of years, but have been clueless about some everyday things close to home in the present.
What Do Geologists Know About the Early Earth?
November 14, 2013
There's not much data, and there's a lot of doubt and debate. That's what a geologist admits about theories of early earth history.
Buck Up; We're Stuck on Earth
November 10, 2013
Star Trek is out, scientists have found. Our bodies can't take extended space travel.
Evolutionary Origin-of-Life Speculations Contradict Each Other
November 9, 2013
Good scientific approaches should converge on the truth. In secular origin-of-life studies, theories run off in all directions, often crashing into one another.
Whale of a Batty Tale on Sonar Evolution
November 4, 2013
How did two animals completely different in size and ancestry, living in very different environments, arrive at the same complex sensing mechanism?
Earth-Like Planet More Like a Lava Lamp
October 31, 2013
It might be an interesting place to visit on Star Trek, but you wouldn't want to live there. Theoretically, it shouldn't even exist.
No Dark Matter Down Here
October 30, 2013
A mile deep in the earth, the most sensitive search to date for dark matter has turned up nothing.
Findings That Comport With Genesis
October 27, 2013
The history of the world and its life could hardly be more different between the Bible's account and that of modern evolutionary naturalism. Some recent scientific reports fit with a designed, recent creation, and do not fit with evolution.
Anthropogenic Global Warming: A Consensus in Crisis
October 24, 2013
Worries and debates emerge from supporters of human-caused global warming – not just skeptics. How does this resemble the creation-evolution debate?
Lord Kelvin Extolled as Giant of Science and Creationist
October 23, 2013
One of the eminent scientists of the 19th century was a Bible-believing creationist, the BBC agrees.
3-D Printing Is a Simplified Form of Biomimetics
October 21, 2013
One of the hottest industrial revolutions in progress is 3-D printing. It can't hold a candle, though, to biological materials construction.
The Ocean's Most Efficient Swimmer Is… A Jellyfish
October 19, 2013
They look so lazy, drifting among the waves, but jellyfish are powered by such efficient mechanisms, the Navy wants to imitate them. | <urn:uuid:25b1f47e-bc66-4262-af47-df69e132c5bf> | 2.796875 | 683 | Content Listing | Science & Tech. | 47.783118 | 95,517,370 |
When comparing C vs C#, the Slant community recommends C for most people. In the question“What is the best programming language to learn first?” C is ranked 2nd while C# is ranked 10th. The most important reason people chose C is:
Learning C forces you to grapple with the low-level workings of your computer (memory management, pointers, etc.) in ways that the other languages abstract away. Without an understanding of these low-level aspects of computer programming you will be limited if you try to develop an application that needs to run in a memory or performance constrained environment. Other languages like Python can obscure a lot of details, so your foundation may be weaker.
Ranked in these QuestionsQuestion Ranking
Pro Understanding of computers
Learning C forces you to grapple with the low-level workings of your computer (memory management, pointers, etc.) in ways that the other languages abstract away. Without an understanding of these low-level aspects of computer programming you will be limited if you try to develop an application that needs to run in a memory or performance constrained environment.
Other languages like Python can obscure a lot of details, so your foundation may be weaker.
Pro Industry standard
C is the industry standard programming language, moreover, it is the most popular programming language to use. C is the language used for most Windows, UNIX and Mac operating systems.
Pro Helps with learning other languages later
Capability to program in C is greatly appreciated in developers, creates an image of competency, and many programmers will learn it at some point in their careers.
C is portable between most hardware. Generally a C compiler is made for any new architecture, and already exists for existing architectures.
C is portable between all operating systems (Windows, UNIX, Mac, etc.) and only needs a program to be recompiled to work. This allows anyone on any operating system to learn about the language and not be held back by intricacies of their operating system.
With this said, C's portability these days is not quite what it used to be. Much of said portability relies on the POSIX standard in particular, and as time passes, the compliance of a given system with that standard is becoming less certain; especially in the case of Linux. Most things will still be portable (or at least emulatable) between Windows, Linux, and FreeBSD for example; but you will at times need to make use of platform-specific support libraries and APIs as well.
Pro Low level of abstraction
While higher level languages languages like Java and Python provide possibilities to be "more expressive" per line of code, it's much more convenient to start with "less efficient" (get me right) language, in order to get initial concepts of how things behave at lower level.
Actually C is a good starting point moving to both higher and lower levels of abstraction, the good example here would be learning C before Assembler, as for general use the Assembler quite hard to understand due to low level of its abstraction (like getting the understanding on how loops work in C before trying to implement them on Assembler).
Pro Teaches good practices
Writing in C will require you to understand how things are done. C implies using and understanding the fundamentals. Learning a higher-level language after is much easier.
Pro If you can't grok C you should not be a professional programmer
It sets an early bar that if you can't hurdle you might as well do something other than programming and not waste any more of your time.
Pro The king of languages, imitated, extended but never equalled
Made of a small set of keywords and rules, only your imagination is the limit. Above all, when it comes to 'pro' programming, C is the only one to rely on.
Pro Basic concepts can be applied to accelerate learning any other language
You can easily pivot knowledge learned here and apply it to almost every other language.
Pro More control over the code
Pro C is simple with lesser rules than any other language
C is standardized and it is the goto language when you have to speed things up
Pro Portable between CPU architectures
C was design to be independent of any particular machine architecture, and so with a little care it is easy to write "portable" programs. By design, C provides constructs that map efficiently to typical machine instructions, and therefore it has found lasting use in applications that had formerly been coded in assembly language like operating systems or small embedded systems.
for first edition of The C Programming Language by Brian Kernighan and Dennis Ritchie
Pro .NET is a great toolbox
C# runs on top of the .NET framework, which provides many libraries containing classes used for common tasks such as connecting to the Internet, displaying a window or editing files. Unlike many other languages, you don't have to pick between a handful of libraries for every small task you want to do.
Pro Awesome IDE for Windows
On Windows, Visual Studio is the recommended C# IDE. It provides a very flexible GUI that you can rearrange the way you want and many useful features such as refactorings (rename a variable, extract some code into a method, ...) and code formatting (you can pick exactly how you want the code to be formatted).
Visual Studio also highlights your errors when you compile, making your debug sessions more efficient since you don't have to run the code to see the mistakes. There's also a powerful debugger that allows you to execute the code step-by-step and even change what part of the code will be executed next. In addition to giving you all the line-by-line information you'll need in a hassle-free manner, Visual Studio has stuff you can click on in the errors window that will take you to the documentation for that error, saving you several minutes of web searching.
In addition to all of this, Visual Studio has an intuitive, intelligent, and helpful graphical user interface designer that generates code for you (the best of WYSIWYG, in my opinion), which is helpful for new programmers. Being able to create a fantastic-looking UI with one's mouse and then optionally tweak with code helps make programming fun for beginner developers.
Visual Studio also has the best code completion --Intellisense is every bit as intelligent as the name says it is. It, as well as VS's parameter hinting, is context-, type-, user-, and position-sensitive, and displays relevant completions in a perfectly convenient yet understandable order. This feature allows a new programmer to answer the questions "What does this do?" and "How do I use it?" right then and there rather than having to switch to a browser to read through extensive documentation. This allows the programmer to satisfy their curiosity before it is snuffed out by several minutes of struggling through exhaustive documentation.
And for the more adventurous and text-ready developer, Microsoft does the best job of ensuring that everything, from interfaces and wildcard types down to Console.WriteLine("") and the + operator, is well-documented and easy to understand, with relevant and well-explained usage examples that manage to be bite-size yet complete, simple yet truly helpful. The reference site is easy to navigate, well-organized, clean and uncluttered, up-to-date, and fresh and enjoyable to look at, and every page is well-written with consideration for readers who are not C# experts yet want to read about changing the console background color.
The best part? It's free! Visual C# Express contains all of the features described above, at zero cost. If you are a student, you can probably get Visual Studio Professional from your university, which also includes tools for unit testing and supports plugins.
Pro Incredibly Well-Engineered Language
Where other languages invoke the feeling of being a product of organic growth over time, C# just feels like an incredibly well-designed language where everything has its purpose and almost nothing is non-essential.
Pro Supports some functional features
C# is primarily object-oriented, but it also supports some features typically found in functional languages such as lambdas, delegates and anonymous classes. Methods can be treated like any other object, and the Linq query system operates on monads with lazy evaluation (though it hides this with a lot of syntactic sugar).
You don't need to use these features to code in C#, though, so you can start with OOP and then learn about them.
Pro Best language for Windows programs
C# is clearly the best choice for Windows programs. The .NET framework contains everything you need to build great-looking apps, without having to learn the confusing Win32 API or download a ton of external libraries. C# can also be used to build Windows 8's "modern" apps.
Pro Great introduction to object-oriented programming
Object-oriented programming is the most widely-used paradigm. C# offers support for common OOP features such as classes, methods and fields, plus some features not found in competing languages like properties, events and static classes.
C# code is much more readable thanks to the syntactic sugar it offers. You can truly concentrate on your code, not on the way it's implemented.
Pro Supported on many platforms
C# can be used for Windows apps, Linux apps, OS X apps, Windows 8 "modern" apps, websites, games, iPhone apps, Android apps, Windows Phone apps, and more.
If you want to create a cross-platform application, you can share most of the code and write one GUI for each platform.
Pro Very high demand in the industry.
Pro Can mix high and low level programming
You can code at the high level without worrying about pointers and memory management, but if you so choose you can switch to lower level programming with direct memory management and pointer manipulation (though you need to compile to specifically allow this).
Pro With ASP CORE a good language to learn
With CORE you are no longer just limited to Windows, so a language worth learning.
Pro Great language for Unity game engine
Unity provides a selection of programming languages depending on preference or knowledge - C#, JS, Boo and UnityScript. C# is arguably the most powerful with better syntax and stronger language structure. It allows using script files without attaching them to any game object (classes, methods inside unattached scripts that can be used at any time). There are more tutorials and information for C# than UnityScript and Visual Studio can be used to code for unity in C#. Additionally, learning C# allows using it outside of Unity as well unlike UnityScript.
Pro .NET truly universal
With .NET core it is a truly universal programming language which support desktop apps (Windows), Mobile apps (Xamarin), Web Apps (ASP.Core MVC). Also is perfectly fit to serverless programming for micro services. Soon it will be also support Web assembly (Blazor).
Con C will require you to learn concepts too advanced for most beginners
While other programmers will learn algorithms and structures and will do magic tricks and awesome applications, you will learn trash info that you should know maybe after 5-7 years experience in software development, not earlier. It's like going the first time as a seven year old kid to first school class, and your teacher tells you to learn you about Discrete Math, without basic math and how to do 2x2.
If you wish to be a really good programmer, C for sure will be in your portfolio, but not as a first language, and this programming language is used only for very hard and very limited tools which require a lot of professional skills from the programmer.
Con Languages is full of corner cases and undefined behaviors
Undefined behavior in a program can cause unexpected results, making it hard to debug. With UB, program behavior may vary wildly depending on optimization settings. There are many cases that invoke UB, such as signed overflow, invalid dereferences, large integer shifts, uninitialized variables, etc. These serve to frustrate novice programmers when they could be learning other concepts.
Con Requires memory management
Learning programming is already hard enough when you don't have to worry about memory leaks.
Con Long learning curve
While the language compliments knowledge of computer components very well, and gives a deeper understanding, it is also quite difficult to learn, and to use correctly, especially without aforementioned knowledge.
Con Heavily outdated programming concepts
C lacks a large majority of programming concepts that modern languages make use of today. The existing functionality of C makes use of outdated and deprecated methodologies which can be of great annoyance to the modern day programmer.
Depending on the purpose this can be either a pro or a con. If the task is to learn how to program, low-level of C will impend learning important concepts. Furthermore, C is rather limited in ways of building abstractions.
"Low-levelness" of C can be a pro feature in learning system programming.
Con Completely lacks type safety
The C standard library is not type safe, and the language itself does not promote type safety built into the language, which leads to error-proneness of the language. If anything, it would be recommended that those interested in C to instead put their time in D, which actually includes a complete copy of the C standard library rewritten to be fully type safe.
Con Does not support modules; header file annoyances
Header files are a poor man's implementation of modules. Modern programming languages make use of modules which eliminate the need for C includes and header files and the many issues caused by them, such as the complete lack of dependency checking. Header files often contain even more include statements that point to other header files which also point to even more which drastically increases compile time. Modules only have to be compiled once, and when importing those modules into your software project, you only have to pull in the module that you are using, which is often times already precompiled. This way, the compiler knows exactly what it needs before beginning to compile your project and can automatically compile the few dependencies it needs in advance rather than recursively compiling every header file it runs across as in C.
Con Arrays are not first class objects
When an array is passed to a function, it is converted to a pointer, even though the prototype confusingly says it's an array. When this conversion happens, all array type information gets lost. C arrays also cannot not be resized, which means that even simple aggregates like a stack are complicated to implement. C arrays also cannot be bounds checked, because they don't know what the array bounds are.
Con Isn't truly portable or cross platform
The C programming language is not portable to other operating systems, and even different compilers, because the C language does not provide any reference cross platform libraries or compilers. Different platforms and compilers provide their own implementation of the C standard library which may not be compatible with the implementation in another compiler or platform. Without cross platform libraries and tools, one cannot state that C is portable. This is in stark contrast to modern programming languages that provide their own cross platform libraries and compilers, such as D, Go and Rust.
Con The need for C developers in the current market is very low, and trending downward
Older languages, like C, are no longer in their hay day. Even if you do learn it as your first language, you are only setting yourself up to need to learn another language in the long run. If you want a skill that you can not only learn from, but also potentially build a career on, C should not be your first choice.
Con Lack of support for first class strings
C does not support the string type, nor does it support UTF-8 strings that modern languages are employing today. Instead of strings, C makes use of the *char type which is a pointer to a character array.
Con Compiles procedurally rather than intelligently
In the same manner that C recursively compiles header files ad infinitum without any sort of dependency checking, C source code is also compiled in the same manner. If you attempt to call a function before it is declared, the compiler will fail because the function was not compiled before it was caled.
Con C structs are very weak and outdated
C structs lack a lot of modern capabilities that are vital in programming languages of today, such as assigning member functions to structs to give them object-oriented capabilities, constructs, deconstructors and RAII. Great care must be used when using structs in C to prevent memory leaks and ridiculously slow structs.
Con Includes require obscene resources to compile
All the modern languages have resulted in ditching the ancient deprecated model of #include statements and have instead adopted the superior model of modules. When compiling software written in C, the programmer is forced to also compile X headers which contain Y headers which contain Z headers and so forth -- drastically increasing the number of lines that need to be compiled. In order to compile something as simple as "Hello, World", for example, 18K lines of code needs to be compiled. This can be very taxing on RAM and CPU resources, causing compile times to quickly absorb a large portion of the programming process.
Con Undefined behaviors and weak limited type safety
Subtle errors can render the entire program "undefined" by the complicated C standard. The standard imposes no requirements in such cases. Thus C compiler is free to ignore the existence of such cases and Bad Things are prone to happen instead. Even experts can't reliably avoid undefined cases in C, so how can beginners be expected to do so? C allows for non-type safe operations such as logic errors, wild pointers, buffer overflow, etc. UB and type safety issues create a large number of bugs and security vulnerabilities.
Con Only offers basic support for source code split into multiple files
Modern programming languages are capable of compiling split source code files by concatenating them together efficiently at compile time before compiling them. However, C requires the developer to resort to messing with header files and makefiles to get similar functionality.
Con Dependecy on IDE
Most people learn and depend on VisualStudio to write C#. The result is people learn how to use an IDE and not the concepts or fundamentals of good programming. This isn't necessarily a knock on the language itself, but it is frustratingly difficult to do things in C# when not using VS.
Con Complex syntax
Too many syntactic constructs to learn before it becomes usable.
Con Lacks standard-library support for immutable data structures
Con Too easy to write multithreading apps that are buggy
Many web frameworks or GUI libraries will push novice users to writing multithreaded code, which leads to frustrating race condition bugs.
Other languages with multithreading push users towards safe constructs, like passing messages and immutable or synchronized containers. But in C# the data structures aren't synchronized by default, and it's too easy to just set a field and observe the result from another thread (until you compile with Release, and now you have a heisenbug).
Con Often-used products in most C# development environments get expensive
The majority of the C# development community uses Microsoft products which are not all free and open-source. As you get into the enterprise level of some of these products and subscriptions, the expense is multiple factors of 10 greater.
While you can use a fully open-source and free C# environment, the community around that is much smaller. While this can be said for other languages as well, the majority of C# falls into the for-pay Microsoft realm. | <urn:uuid:b4abd126-d609-490f-8cdf-f651fb61a342> | 2.765625 | 4,037 | Listicle | Software Dev. | 39.757806 | 95,517,392 |
Washington: Astronomers have recently captured the first significant X-class solar flare on March 11, 2015.
NASA's Solar Dynamics Observatory, which watches the sun constantly, captured an image of the event. Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however, when intense enough, they can disturb the atmosphere in the layer where GPS and communications signals travel.
This flare was classified as an X2.2-class flare. X-class denotes the most intense flares, while the number provides more information about its strength. An X2 would be twice as intense as an X1, an X3 would be three times as intense, etc. | <urn:uuid:c4891f2f-1b6c-444b-b9d4-a29eaebf1d79> | 4.0625 | 149 | News Article | Science & Tech. | 51.315 | 95,517,398 |
An aquifer formed in alluvial sediments of the river Great Morava, spreading across over 1,000 km2, represents one of the most important resources for supplying settlements with drinking water. In this area, numerous settlements were built and the agricultural production is present. The first aquifer was formed in gravel-sandy sediments, 20 m thick, of large permeability and it is naturally protected with clay-dusty roof, with thickness of about 5 m. The biggest problem is registered presence of nitrates in groundwater, above the valid MPL values for drinking water that is 50 mgNO3/l. Monitoring the state and problems of separate water sources, formed in this area, showed the considerable larger influence of settlements without sewage systems than existing agricultural production. Analysis showed that nitrates input by groundwater into the River Danube and the Black Sea is negligible. Considering the anthropogenic impacts in the wider surrounding of the water source, we came to conclusions that can be used for further planning the use of this and similar groundwater resources.
Research Article|November 01 2007
State and problems of using alluvial groundwater in Great Morava Valley
Water Science and Technology: Water Supply (2007) 7 (3): 59-67.
Dj. Boreli-Zdravkovic, M. Damjanovic; State and problems of using alluvial groundwater in Great Morava Valley. Water Science and Technology: Water Supply 1 November 2007; 7 (3): 59–67. doi: https://doi.org/10.2166/ws.2007.067
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Ecological Succession and Community Dynamics
“Ecological Succession” is an ordered progression of structural and compositional changes in communities toward an eventual unchanging condition, the climax community 1 –3. The term “Community” is used in two ways 4. The “Abstract Community” refers to an abstract group of organisms that recurs on the landscape, a definition, which usually carries with it an implication of a level of integration among its parts that in extreme could be called organismal or quasi-organismal; the “Concrete Community” concept refers to the collection of organisms found at a specific place and time. These terms and their meanings are topics of significant debate among ecologists, both historically and today 5, 6. These differences in the meaning and cause of ecological succession strongly affect the formulation of policies for ecosystems management and restoration.
KeywordsBoreal Forest Vegetation Dynamic Site Index Sustainability Science Yield Table
- Abstract community
A group of organisms that recurs on the landscape with an implication of a level of integration among its parts that in extreme could be called organismal or quasi-organismal (see: Concrete Community).
A space-for-time substitution in which the successional vegetation is ordered in a regular fashion. An example would be the series of vegetation at the foot of a receding glacier or a series of sand dunes ordered in regularly aged series.
- Clementsian succession
An explanation of succession emphasizing the attributes of the community as if it functioned like a single living organism (see: Abstract Community).
- Climax community
An ecological community associated with a particular climate and in a state of dynamic equilibrium with the climate. The American ecologist, F.E. Clements, designated the climax community as the endpoint of ecological succession for a given climate condition and noted the common Greek root κλίμα (clima) or inclination, in both climax and climate as indicating their close relationship.
- Concrete community
The collection of organisms found at a specific place and time (see: Abstract Community).
- Gleasonian succession theory
An explanation of succession emphasizing the importance of the attributes of individual organisms as the fundamental basis.
- Indicator species
Plants or animals whose presence implies the past or present conditions at a given location.
The concept that one mature vegetation will eventually be produced by successional processes in a given region.
The concept that multiple mature, stable-vegetation types can develop from the successional processes operating in a given region.
A school of vegetation science emphasizing the classification of vegetation.
- Time-for-space substitution
The collection of vegetation data from different locations at which succession has been initiated at different times in the past to piece together the pattern of succession.
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- 77.Stolbovoi V, McCallum I (eds) (2002) CD-ROM land resources of Russia. International Institute for Applied Systems Analysis and the Russian Academy of Science, LaxenburgGoogle Scholar
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Global Warming: Fact or Fiction? Presented By: Kenyatta Esters Rhonda Nichols What is Global Warming? Refers to a general warming trend of the earth Possible causes: Tectonic Astronomical Green house gasses Other Atmospheric conditions 1880-2000 1950-2000
18% 27x CO2
Synthetic Gasses (CFC’s) and other
6% CFC10,000x CO2
CFC substitutes 300-5,000xCO2
“Careful measurements have confirmed that CO2 is increasing in the atmosphere and that human activities are the primary cause…
Is it a DIRECT consequence of fossil fuel use?
Do we have an ethical obligation to reduce CO2 emissions? | <urn:uuid:1dc4a6e6-f20e-4ca7-a52a-eac8221d2185> | 2.53125 | 151 | Content Listing | Science & Tech. | 41.6825 | 95,517,407 |
Paper prototyping in action
In human-computer interaction, paper prototyping is a widely used method in the user-centered design process, a process that helps developers to create software that meets the user's expectations and needs--in this case, especially for designing and testing user interfaces. It is throwaway prototyping and involves creating rough, even hand-sketched, drawings of an interface to use as prototypes, or models, of a design. While paper prototyping seems simple, this method of usability testing can provide a great deal of useful feedback which will result in the design of better products. This is supported by many usability professionals.
Paper prototyping started in the mid 1980s and then became popular in the mid 1990s when companies such as IBM, Honeywell, Microsoft, and others started using the technique in developing their products. Today, paper prototyping is used widely in user centered design by usability professionals. More recently, digital paper prototyping has been advocated by companies like Pidoco due to advantages in terms of collaboration, flexibility and cost.
Paper prototyping saves time and money since it enables developers to test product interfaces (from software and websites to cell phones and microwave ovens) before they write code or begin development. This also allows for easy and inexpensive modification to existing designs which makes this method useful in the early phases of design. Using paper prototyping allows the entire creative team to be involved in the process, which eliminates the chance of someone with key information not being involved in the design process. Another benefit of paper prototyping is that users feel more comfortable being critical of the mock up because it doesn't have a polished look.
There are different methods of paper prototyping, each of them showing several benefits regarding the communication within the development team and the quality of the product to be developed: In the development team paper prototypes can serve as a visual specification of the graphical user interface, and by this means assure the quality of a software. Prototyping forces a more complete design of the user interface to be captured. In team meetings they provide a communication base between the team members. Testing prototypes at an early stage in development helps to identify software usability problems even before any code is written. The costs and annoyances of later changes are reduced, the support burden is lowered, and the overall quality of the software or website is increased.
Paper prototyping is the quick way to generate the digital ideas by sketching on the paper. In tight VPC workshop, the quick ideas need to be explored and evaluated. Usually, paper prototyping is preferred as the tools to generate the ideas by visually and evaluate in the team and with target customers.
Paper prototypes should be considered when the following is true:
- When the tools the designer wants to use in creating a prototype are not available.
- When the designer wants to make a sincere effort to allow all members of a team, including those with limited software skills, to take part in the design process.
- When tests of a design lead to a great deal of drawings.
- When the ideas need to be generated fast and evaluated in a short period of time
- When there is a cocreation workshop need customers and designers to get the ideas together
The most important areas of application of paper prototypes are the following:
- Communication in the Team
- One of the major applications of paper prototyping is brainstorming in the development team, to collect and visualize ideas on how an interface might look. The interface is built up step by step, meeting the expectations of all team members. To probe the applicability of the software design, typical use cases are played through and possible pitfalls are identified. The prototype can then be used as a visual specification of the software.
- Usability Testing
- Paper prototypes can be used for usability testing with real users. In such a test, the user performs realistic tasks by interacting with the paper prototype. The prototype is manipulated by another person reflecting the software's reactions to the user input actions. Though seemingly unsophisticated, this method is very successful at discovering usability issues early in the design process.
- Three techniques of paper prototyping used for usability testing are comps (short for compositions), wireframes, and storyboards. Comps are visual representations, commonly of websites, that demonstrate various aspects of the interface including fonts, colors, and logos. A wireframe is used to demonstrate the page layout of the interface. Lastly, the storyboards are a series or images that are used to demonstrate how an interface works. These three techniques are useful and can be turned into paper prototypes.
- Design testing
- Especially in web design, paper prototypes can be used to probe the illegibility of a design: A high-fidelity design mockup of a page is printed and presented to a user. Among other relevant issues the user is asked to identify the main navigation, clickable elements, etc. Paper prototyping is also the recommended design testing technique in the contextual design process.
- Information architecture
- By applying general and wide paper prototypes, the information architecture of a software or web site can be tested. Users are asked where they would search for certain functionality or settings in software, or topics in a web site. According to the percentage of correct answers, the information architecture can be approved or further refined.
- Rapid prototyping
- Paper prototyping is often used as the first step of rapid prototyping. Rapid prototyping involves a group of designers who each create a paper prototype and test it on a single user. After this is done, the designers share their feedback and ideas, at which point, each of them creates a second prototype--this time using presentation software. Functionality is similarly unimportant, but in this case, the aesthetics are closer to the final product. Again each designer's computer prototype is tested on a single user, and the designers meet to share feedback. At this point, actual software prototypes can be created. Usually after these steps have been taken, the actual software is user-friendly the first time around, which saves programming time.
- ^ Carolyn., Snyder, (2003). Paper prototyping : the fast and easy way to design and refine user interfaces. San Francisco, Calif.: Morgan Kaufmann, Elsevier Science. ISBN 9780080513508. OCLC 63116735.
- ^ Klee, M. (2000). "Five paper prototyping tips".
- ^ Arnowitz, J.; Arent, M.; Berger, N. (2006). Effective Prototyping for software makers. Morgan Kaufmann.
- ^ Sefelin, R.; Tscheligi, M.; Giller, V. (2003). "Paper prototyping - what is it good for?: a comparison of paper- and computer-based low-fidelity prototyping". CHI '03 Extended Abstracts on Human Factors in Computing Systems. ACM: 778-779. doi:10.1145/765891.765986.
- ^ Snyder, Carolyn (2003). Paper Prototyping: the fast and easy way to design and refine user interfaces. San Francisco, CA: Morgan Kaufmann. | <urn:uuid:b4a05254-bab2-40c8-9dc5-ad1325e38a97> | 3.1875 | 1,462 | Knowledge Article | Software Dev. | 32.416393 | 95,517,449 |
This is a very simple tool (read: hacky) designed to allow a computer behind a router to expose local ports without setting up port forwarding on the router. It has the additional benefit that the computer does not need to setup a static (known) IP address.
It works under the assumption that there exists a 3rd machine that both the NAT-ed computer and requesters for the NAT-ed computer can contact.
This is best illustrated via example. Suppose user A is behind a NAT, wants to establish a service (say an HTTP server) on port N that user B can connect to. Suppose that A and B are not behind the same NAT. Now suppose A and B can both connect to server C, which as address X. Here's how to use this tool to make this happen:
Pick a port M such that N != M. Now on server C, run:
python server.py N M
Now user A runs:
python client.py X M N
Additionally, user A starts up his service on port N locally.
Now, user B can connect to user A's service by simply using the address X:N.
The tool is currently very unstable, but it works to forward a simple HTTP server on user A's machine. | <urn:uuid:7ac974f0-df7a-4405-b00d-cf9784873ff6> | 3.046875 | 261 | Product Page | Software Dev. | 75.241667 | 95,517,453 |
The U.S. Navy's Joint Typhoon Warning Center noted that just before Super-Typhoon Haiyan made landfall its maximum sustained winds were 314 kph/195 mph, with gusts up to 379 kph/235 mph. PAGASA, the Philippines Weather organization noted that Hiayan's maximum sustained winds at landfall were near 234 kph/145 mph.
As Super-Typhoon Haiyan moved over the central Philippines on Nov. 8 at 05:10 UTC/12:10 a.m. EDT, the MODIS instrument aboard NASA's Aqua satellite captured this visible image.
Image Credit: NASA Goddard MODIS Rapid Response Team
On Nov. 7 at 2100 UTC/4 p.m. EDT/Nov. 8 at 5 a.m. Philippines local time, Super-Typhoon Haiyan had maximum sustained winds near 170 knots/ 195.6 mph/314.8 kph. It was located about 543 nautical miles east-southeast of Manila at that time.
As Super-Typhoon Haiyan moved over the central Philippines on Nov. 8 at 05:10 UTC/12:10 a.m. EDT, the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA's Aqua satellite captured a visible image. The image showed that Haiyan maintained its structure as it moved over the east central Philippines. As the center moved through the eastern Visayas, large, thick bands of thunderstorms spiraled into the center from the northeast. Hiayan's clouds extended over the entire country from the Cagayan Valley in the north to the Soccsksargen region in the south.
The AIRS instrument that also flies aboard NASA's Aqua satellite captured infrared imagery of Super-Typhoon Haiyan exiting the western Philippines. The coldest cloud top temperaetures and most powerful thunderstorms with heavy rainfall potential covered the Visayas, Bicol, National Capital, Central Luzon, Calabarzon, Northern Mindanao, and Mimaropa regions.
By Nov. 8 at 0900 UTC/4 a.m. EDT/5 p.m. Philippines local time, Haiyan's maximum sustained winds dropped to 145 knots/167 mph/268.5 kph, still making it a powerful Category 5 tropical cyclone on the Saffir-Simpson Scale. It was moving through Western Visayas and was 214 nautical miles south-southeast of Manila. It is moving quickly to the west at 22 knots/25.3 mph/40.74 kph, which will reduce flooding potential.
Many warnings are still in effect today, Nov. 8, as Hiayan continues to exit the western Philippines.
Public storm warning signals have been raised in large areas of the country. In Luzon, Signal #1 was in effect for: Metro Manila, Bataan, Cavite, Rizal, Laguna, Quezon, Camarines provinces, Albay, Sorsogon. Signal #2 is in effect for: Lubang Island, Batangas, Marinduque, rest of Palawan, Burias Island, Masbate and Ticao Island; Signal #3 in effect for the rest of Mindoro provinces, Romblon, rest of northern Palawan including Puerto Princesa City; and Signal #4 is in effect for: extreme northern Palawan, Calamian Group of Islands, southern Occidental and Oriental Mindoro.
In Visayas, Signal #1 remained in effect for: Samar provinces, Leyte provinces, Camotes island, Bohol and Siquijor; while Signal #2 is up for: Negros provinces, Cebu, Biliran Island; and there is no Signal #3, but there is a Signal #4 for Aklan, Capiz, Antique, Iloilo and Guimaras.
In Mindanao, a Signal #1 remained in effect for the Camiguin, Surigao del Norte, Dinagat; and a Signal #2 is up for: Siargao. According to PAGASA, the Philippine authority on meteorology, flashfloods and mudslides are possible in areas under signal #2, 3 and 4. In addition, storm surges of up to 21 feet/~7 meters are possible under a Signal #2.
CNN reported on Nov. 9 that Hiayan left power outages, flooded streets, downed trees, damaged buildings and many canceled flights.
The U.S. Navy's Joint Typhoon Warning Center in Hawaii said it was the strongest tropical cyclone in the world this year.
Hiayan is forecast to move through the South China Sea and make a final landfall as a strong typhoon in central Vietnam in a couple of days.Text credit: Rob Gutro
Rob Gutro | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
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The Global Geometry of Surfaces
In this chapter, we will consider some problems in the global differential geometry of surfaces. A “global” problem can be described as one which in general cannot be stated locally in terms of one coordinate system on a surface with a Riemannian metric, but must necessarily involve the total behavior of the surface. Most often, this total behavior is related to the topology of the surface. For example, Theorem (6.3.5) equates the integral of the curvature function K(p) over a compact surface M with a topological invariant of M (the Euler characteristic). Neither of these two quantities can be described completely in terms of a single coordinate system.
KeywordsRiemannian Manifold Fundamental Group Conjugate Point Closed Geodesic Compact Surface
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And you thought the sexual battles between people could get weird and fierce? Try ants.
In a new study, biologists at the University of Vermont have discovered some queen ants that make sexual bondage into a life and death fight.
The red queen in the middle is mating with the upside-down male on the right. Their copulatory organs are locked in place, so the male can completely let go of the queen with his legs and still be firmly attached. The ant on the left is a competitor male trying to get in on the action.
Credit: Michael Herrmann and Sara Helms Cahan
In a discovery new to science, their research shows that sexual conflict between two species can drive an evolutionary bedroom-battle royal, leading to competing adaptations in which female ants of one species manage to manhandle sperm away from the unwitting males of a different species during intercourse. The study was published in the October 29 online edition of the Proceedings of the Royal Society B.
In the desert along the Arizona/New Mexico border, the scientists observed mating between two species of Pogonomyrmex harvester ants that are known to hybridize. The queens of one species will happily mate with males of another species. But these queens have a trick in their antly boudoir: they only use this sperm from the other species to produce sterile worker ants that they need to build their colonies.
This, you might imagine, isn't what the male ants are hoping will happen with their precious seed. Sure, these males will produce lots of daughters via this queen, but these daughters will be sterile and "so they'll have no grandchildren," says Sara Helms Cahan, a biologist at UVM who co-led the study with her graduate student and lead author Michael Herrmann.
Sterile offspring are directly contrary to the males' long-term evolutionary interest in passing on their genes. So why do these males agree to hook up with these queens in the first place? In the field studies, Herrmann observed that the males—in the once-a-year mad scrum of competitive mating that these harvester ants exhibit following summer monsoon rains—didn't seem able to distinguish queens of their own species from queens of the other species. That is, they couldn't tell them apart until they began to copulate.
Then—perhaps a bit like other dawnings of awareness among males of a well-known species in the middle of the sex act—the male ants figure out they've made a big mistake. Realizing that they have mated with the wrong species, they get clever, and reduce the rate at which they transfer their sperm into these crosstown queens. "They can mate again," Helms Cahan explains, "so this would preserve their sperm for investment into better mating."
But the queens will not be jilted so easily. They have evolved another trick to counteract the males' strategy: hold on and don't let go. "They lock slow males in copula significantly longer," says Helms Cahan, "until they eventually deliver the same amount of sperm that they normally would have." Score one for the queens.
"Essentially, they are sperm parasites," she says.
The new ant study is a "rather unusual R-rated example," Helms Cahan says, of a larger biological phenomenon called the Red Queen hypothesis. Like the Red Queen in Alice in Wonderland—who says, "you see, it takes all the running you can do, to keep in the same place"—the theory proposes that many plants and animals must constantly adapt and evolve not just to gain reproductive advantage but also to simply avoid extinction when competing against opposing, and also-evolving, organisms in the endless shifting of life.
"In this harvester ant system there really needs to be some sort of stalemate," Herrmann explains, "because if the males actually were able to tell what type of female they were mating with, they would cut off the sperm to the queens that need it." Then the system would collapse because these queens have evolved to only be able to produce workers with sperm of the other species, but not their own.
There is "a conflict of interests," the scientists write in the journal article "as queens must mate with both lineages to produce both daughter queens and the workforce to care for them, but males gain fitness returns only by mating with queens of their own lineage."
The new study is also a powerful illustration of the fact that in the wider biological world, "females are not just passive players in reproduction," Helms Cahan says, "they have their own distinct evolutionary interests, and are just as capable of imposing those interests on their partners when conditions warrant."
Joshua Brown | EurekAlert!
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
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
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17.07.2018 | Materials Sciences
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It’s late April and workers are assembling the last parts of the National Ignition Facility (NIF), a sprawling building covering the area of three football fields at Lawrence Livermore National Laboratory in Livermore, CA. Dressed in hard hats, hair nets, lab coats, and latex gloves, they have gathered at the target chamber, a sphere 10 meters in diameter and bristling with 48 burnished-aluminum ducts that together house 192 separate laser beams. Each beam on its own is one of the world’s most powerful, says Bruno Van Wonterghem, operations manager at NIF. Together they deliver 50 to 60 times the energy of any other laser.
The workers are preparing to install a key piece of equipment–the target-alignment sensor–at the end of a tapered boom that can be extended into the center of the chamber. Scientists will use the sensor to position a gold canister the size of a pencil eraser at the center of the sphere and align it with the laser beams. In a series of experiments over the coming months, if all goes according to plan, those lasers will strike the gold canister with a pulse 3 to 20 nanoseconds long, generating a bath of high-energy x-rays. These in turn will cause a two-millimeter pellet containing hydrogen isotopes to implode. “All of that kinetic energy gets transformed into heat,” says Van Wonterghem. The hydrogen pellet will reach a temperature of 100 million °C and a density 100 times that of lead–enough to start a fusion reaction.
Fusion, in which atomic nuclei combine to form atoms of a new element, is the key reaction fueling nuclear bombs and the sun. (In the NIF experiments, hydrogen isotopes combine to form helium nuclei while releasing neutrons and x-rays.) It has also long been held up as a potential source of abundant energy, if only the reactions could be harnessed in a controlled setting. That’s challenging, because a plasma hot enough for hydrogen nuclei in it to fuse is so hot that it would destroy any containment material. Scientists have conceived two general solutions. The first and most mainstream is to confine the plasma in a powerful electromagnetic field. That is what’s supposed to happen at the multinational, $14 billion ITER project in France, which is expected to be operational by 2018.
NIF takes a fundamentally different tack. By using lasers to compress the hydrogen fuel, it will mimic the extreme heat and density inside a star. The resulting fusion reaction is controlled not by confining it electromagnetically but by limiting the amount of fuel. NIF will produce a tiny thermonuclear explosion, so small that it can be studied in a 10-meter chamber. In fact, NIF’s primary mission is to shed light on high-temperature and high-density physics, including the reactions in nuclear weapons, by re-creating conditions inside stars and bombs.
Researchers debate which approach will be the most useful for generating electricity; so far it’s too early to be sure. But it looks likely that NIF will be the first facility to reach a significant milestone in the quest for laser-based fusion power: the ignition of a self-sustaining reaction that produces more energy than was put in by the laser. Previous experiments and computer simulations suggest that the 192 lasers at NIF are powerful and precise enough to set off such a chain reaction–one that will continue to burn until the hydrogen fuel runs out.
There are still huge challenges to be met before fusion can be harnessed to generate electricity. But achieving controlled fusion burn “will be an incredible event,” says Edward Moses, a principal associate director at Livermore who’s in charge of NIF. “We think we’re coming to a new era.”
Igniting fusion won’t be easy. It requires a facility that can marshal vast amounts of power but control it so precisely that it can be aimed at targets measured in micrometers. That, says Ian Hutchinson, a professor of nuclear science and engineering at MIT, will be “an incredibly impressive technological achievement.”
On the same afternoon when technicians worked to install the target-alignment sensor, others have started to gather in the facility’s control room, with its large screens and clusters of workstations. They’re preparing for a test shot of the laser, minus the fusion pellet; as a safety precaution, it’s been scheduled for night, after the facility’s laser bays and target chamber have been cleared of workers.
Firing the laser requires setting 60,000 different control points. The sequence of events that delivers the laser pulse to the target is too complex for human control, Van Wonterghem says, so after the settings are selected, a network of 1,500 computers will take over and carry out the final countdown, with the researchers’ hands hovering near the many emergency-shutdown buttons arranged throughout the room.
If it all works, the lasers will deliver a pulse of power 500 times greater than the peak electricity-generating capacity of the United States. The pulse will ignite the thermonuclear explosion–essentially creating a tiny star.
Significant hurdles will remain before such a process can be used to generate electricity. The fusion reactions are expected to produce 10 to 20 times the amount of energy delivered by the lasers. But this does not take into account the energy needed to make the lasers in the first place: converting electricity into laser light is an inefficient process. Making up for the wasted energy, and producing enough extra to generate electricity, would require fusion reactions that generate about 100 times the energy delivered by the lasers.
Speaking in a cluttered office near NIF, Moses says there are at least two potential ways to get around this problem. One requires combining two laser pulses in a process called fast ignition. In theory, this could reduce the amount of laser energy needed to ignite a sustained reaction. NIF, however, isn’t currently set up for this; it’s an approach that will be taken by other laser fusion projects now under construction, and eventually by NIF as well.
The other approach, Moses says, is to combine fusion with fission, the reaction used in conventional nuclear power plants. This option doesn’t offer the same prospect of nearly limitless energy as fusion alone, but it could increase by orders of magnitude the amount of energy that can be extracted from uranium, greatly enhancing this already abundant source of fuel. At the same time, it could remove the chief objection to nuclear fission by eliminating almost all the long-lived radioactive waste it typically produces. “Right now we only get half a percent to 1 percent of the available energy,” Moses says. “We can get 99-plus out.”
The researchers at NIF have developed a detailed conceptual plan for pairing fusion and fission. The reason nuclear reactors use only a fraction of the energy in uranium is that as reaction products accumulate, they eventually interfere with the chain reactions needed to keep generating power. Fusion can supply a stream of neutrons that can keep these reactions going, using up almost all the energy in the fuel.
To be sure, not everyone agrees that laser-based fusion power will work. And some skeptics question whether NIF in particular can achieve self-sustained fusion, saying that the facility cannot produce sufficiently high-energy laser pulses without either damaging the laser optics or losing the tight focus on the target needed to compress the fuel evenly. Even if the facility achieves sustained fusion, producing electricity in a power plant would require lasers that could ignite a new fuel pellet 10 to 15 times a second. The NIF lasers, which have to be cooled down between shots, can be fired at most once every two to four hours. “Even if NIF is as successful as hoped, they’ll still be a very long way from being in a position to turn this into a practical energy source,” Hutchinson says.
NIF has already seen some signs of success. Earlier this year, all 192 lasers were fired at once and reached energy levels that will be enough to ignite fusion. Still, earlier laser projects at Livermore were supposed to achieve fusion ignition and didn’t. Although a lot has been learned since then, there’s no guarantee it will work this time. The good news is that it won’t be long until the researchers know: after a series of test shots, they hope for success within the next two years. “We’re looking forward to hearing some results,” Hutchinson says.
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:01e0f784-48bf-44ff-af0c-4dc63d1ef67e> | 3.375 | 1,826 | News Article | Science & Tech. | 42.489 | 95,517,506 |
A staff of worldwide researchers is thanks to established off for the world’s greatest iceberg on Wednesday, combating huge waves and the encroaching Antarctic winter season, in a mission aiming to solution basic concerns about the impact of local weather change in the polar areas.
The scientists, led by the British Antarctic Study (BAS), are making an attempt to attain a recently exposed ecosystem that experienced been concealed for 120,000 a long time below the Larsen C ice shelf on the Antarctic peninsula.
In July very last 12 months, part of the Larsen C ice shelf calved away, forming a large iceberg – A68 – which is 4 moments larger than London, and revealing existence beneath for the 1st time.
Large iceberg splits from Antarctic ice shelf
Now scientists say it is a race against time to investigate these new ecosystems ahead of they are transformed by publicity to the light.
Maritime biologist Dr Katrin Linse from the BAS is foremost the mission which sets off on a voyage across the Southern Ocean from the Falklands Islands on Wednesday. They expect to achieve the iceberg inside of a 7 days.
“The calving of A68 gives us with a distinctive prospect to study maritime lifestyle as it responds to a dramatic environmental change,” she stated. “It’s critical we get there rapidly just before the undersea environment modifications as sunlight enters the h2o and new species start to colonise … It’s really fascinating.”
Prof David Vaughan, science director at BAS, explained: “We want to be bold on this 1. Larsen C is a extended way south and there’s heaps of sea ice in the spot, but this is critical science, so we will try out our very best to get the staff exactly where they need to have to be.”
He explained local weather change had currently afflicted the seas all around Antarctica and is warming some coastal waters.
“Future warming might make some habitats heat. The place these habitats assist special species that are tailored to love the chilly and not the warm, individuals species are going to both go or die. How fast species can disperse, and how fast ecosystems can colonise new areas, is key to understanding where the Antarctic is likely to be resilient, and the place it is susceptible.”
Previous week the Guardian printed the initial photos of creatures found in a earlier unexplored area of the Antarctic seabed
, taken in the course of a Greenpeace research expedition to the Antarctic which is element of a wider campaign to change a large section of the area into the world’s greatest ocean sanctuary.
Speaking onboard the Greenpeaceship Arctic Dawn, the group’s head of oceans, Will McCallum, stated there was “still so significantly left to find out about ocean daily life right here in the Antarctic.”
“From concealed ecosystems exposed by calving icebergs, to our research missions to the seafloor which have discovered an abundance of uncommon and vulnerable species. This area is bursting with lifestyle and a huge Antarctic Ocean sanctuary would help us defend it in all its types.”
There is expanding concern about the possible effect of climate adjust in the Antarctic.
Earlier this month, a report uncovered that melting ice sheets in Greenland and Antarctica are rushing up the currently quickly tempo of sea amount increase.
The study printed by the Nationwide Academies of Sciences stated at the recent charge, the world’s oceans will be on common at the very least 60cm (2ft) increased by the stop of the century.
However it found that the method is accelerating, and much more than a few-quarters of the acceleration because 1993 is due to melting ice sheets in Greenland and Antarctica, the study demonstrates.
Authorities say the spot close to the Antarctic peninsula has observed widespread ice shelf decay and collapse in current decades, major to “glacier acceleration” and elevated discharge of ice from the Antarctic continent into the sea.
Nonetheless researchers are cautious of attributing the calving of the Larsen C iceberg straight to world-wide warming.
Adrian Luckman, professor of glaciology at Swansea University and chief of a undertaking researching the point out of the ice shelf, explained: “Whilst Larsen C ice shelf has lowered in spot given that data commenced, suggesting that in excess of the extended-phrase the surroundings of the Antarctic peninsula is turning out to be significantly less in a position to assist ice cabinets, we have no proof to hyperlink this particular calving function to modifying situations. Iceberg calving is a all-natural part of the ice shelf cycle and, whilst massive, the calving of A68 is not unparalleled.”
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The pigment, copper phthalocyanine (CuPc), which is similar to the light harvesting section of the chlorophyll molecule, is a low-cost organic semiconductor that is found in many household products.
Crucially, it can be processed into a thin film that can be readily used for device fabrication, a significant advantage over similar materials that have been studied previously.
Now, researchers from the London Centre for Nanotechnology at UCL and the University of British Columbia have shown that the electrons in CuPc can remain in 'superposition' – an intrinsically quantum effect where the electron exists in two states at once - for surprisingly long times, showing this simple dye molecule has potential as a medium for quantum technologies.
The development of quantum computing requires precise control of tiny individual "qubits", the quantum analogs of the classical binary bits, '0' and '1', which underpin all of our computation and communications technologies today. What distinguishes the "qubits" from classical bits is their ability to exist in superposition states.
The decay time of such superpositions tells us how useful a candidate qubit could be in quantum technologies. If this time is long, quantum data storage, manipulation and transmission become possible.
Lead author Marc Warner from the London Centre for Nanotechnology, said: "In theory, a quantum computer can easily solve problems that a normal, classical, computer would not be able to answer in the lifetime of the universe. We just don't know how to build one yet.
"Our research shows that a common blue dye has more potential for quantum computing than many of the more exotic molecules that have been considered previously."
CuPc possesses many other attributes that could exploit the spin of electrons, rather than their charge, to store and process information which are highly desirable in a more conventional quantum technology. For example, the pigment strongly absorbs visible light and is easy to modify chemically and physically, so its magnetic and electrical properties can be controlled.
Dr Warner added: "The properties of copper phthalocyanine make it of interest for the emerging field of quantum engineering, which seeks to exploit the quantum properties of matter to perform tasks like information processing or sensing more effectively than has ever been possible."
Notes for editors
1. For more information or to speak to Dr Marc Warner, please contact Clare Ryan in the UCL Media Relations Office on tel: +44 (0)20 3108 3846, mobile: +44 07747 556 056, out of hours +44 (0)7917 271 364, e-mail: email@example.com
2. 'Potential for Spin-Based Information Processing in Metallo-Organic Semiconductors', DOI: 10.1038/nature12597, is published online today in Nature. For copies of the paper please contact UCL Media Relations.
3. An image illustrating the research is available to journalists on request from UCL Media Relations. Caption: Phthalocyanine thin film on a flexible plastic substrate, showing the coexistence of long-lived "0" and "1" qubits on the copper spin. The molecules form a regular array together with the metal-free analogues, and the background represents the lattice fringes of the molecular crystals obtained by transmission electron microscopy."
About UCL (University College London)
Founded in 1826, UCL was the first English university established after Oxford and Cambridge, the first to admit students regardless of race, class, religion or gender and the first to provide systematic teaching of law, architecture and medicine.
We are among the world's top universities, as reflected by our performance in a range of international rankings and tables. According to the Thomson Scientific Citation Index, UCL is the second most highly cited European university and the 15th most highly cited in the world.
UCL has nearly 27,000 students from 150 countries and more than 9,000 employees, of whom one third are from outside the UK. The university is based in Bloomsbury in the heart of London, but also has two international campuses – UCL Australia and UCL Qatar. Our annual income is more than £800 million.
Clare Ryan | 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.
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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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Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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12.07.2018 | Event News
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19.07.2018 | Power and Electrical Engineering
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On Earth, bursts of particles spewed by the Sun spark shimmering auroras, like the Northern Lights, that briefly dance at our planet’s poles. But, on Jupiter, there’s an auroral glow all the time, and new observations show that this Jovian display sometimes flares up because of a process having nothing to do with the Sun.
Jupiter watchers have long known that the giant planet’s ever-present polar auroras – thousands of times brighter and many times bigger than Earth – are powered by both electrically charged particles from the Sun colliding with Jupiter’s magnetic field and a separate interaction between Jupiter and one of its many moons, called Io.
In this artist’s rendering, flows of electrically charged ions and electrons accelerate along Jupiter’s magnetic field lines (fountain-like blue curves), triggering auroras (blue rings) at the planet’s pole. Accelerated particles come from clouds of material (red) spewed from volcanoes on Jupiter’s moon Io (small orb to right). Recent observations of extreme ultraviolet emissions from Jupiter by satellite Hisaki (left foreground) and the Hubble Space Telescope (right) show episodes of sudden brightening of the planet’s auroras. Interactions with the excited particles from Io likely also fuel these auroral explosions, new research shows, not interactions with particles from the Sun.
Credit: Japan Aerospace Exploration Agency
But there are also auroral explosions on Jupiter, or periods of dazzling brightening, similar to auroral storms on Earth, that no one could definitively trace back to either of those known causes.
In the aurora-making interaction of Jupiter and Io, volcanoes on the small moon blast clouds of electrically charged atoms (ions) and electrons into a region surrounding Jupiter that’s permeated by the planet’s powerful magnetic field, thousands of times stronger than Earth’s.
Rotating along with its rapidly spinning planet, the magnetic field drags the material from Io around with it, causing strong electric fields at Jupiter’s poles. The acceleration of the ions and electrons produce intense auroras that shine in almost all parts of the electromagnetic spectrum but most brightly in high-energy bands, like ultraviolet light and X-rays, that are invisible to unaided human eyes.
Now, new observations of the planet’s extreme ultraviolet emissions show that bright explosions of Jupiter’s aurora likely also get kicked off by the planet-moon interaction, not by solar activity.
A new scientific paper about these observations by Tomoki Kimura of the Japan Aerospace Exploration Agency (JAXA), in Sagamihara, Kanagawa, Japan, and his colleagues, was published online today in Geophysical Research Letters, a journal of the American Geophysical Union.
Starting in January 2014, a telescope aboard the JAXA’s Hisaki satellite, which focused on Jupiter for two months, recorded intermittent brightening of the giant planet’s aurora. The telescope detected sudden flare-ups on days when the usual flow of charged particles from the Sun, known as the solar wind, was relatively weak.
Additional space and ground-based telescopes, including the Hubble Space Telescope, also viewed Jupiter during these lulls in the solar wind. Both Hisaki and Hubble witnessed explosions of the planet’s aurora despite the solar wind’s calm, suggesting that it’s the Jupiter-Io interaction driving these explosions, not charged particles from the Sun, according to the new study. The new research does not address exactly what is happening in the Jovian magnetosphere to cause the temporary brightening of auroral explosions.
The American Geophysical Union is dedicated to advancing the Earth and space sciences for the benefit of humanity through its scholarly publications, conferences, and outreach programs. AGU is a not-for-profit, professional, scientific organization representing more than 60,000 members in 139 countries. Join the conversation onFacebook, Twitter, YouTube, and our other social media channels.
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Further reports about: > American Geophysical Union > Geophysical > Geophysical Research > Geophysical Research Letters > Hubble Space Telescope > JAXA > Japan Aerospace Exploration Agency > Jupiter > Sun > explosions > ions and electrons > magnetic field > observations > powerful magnetic field > solar wind > ultraviolet > ultraviolet light
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.
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Last week, the United States was convulsed by some extremely unusual weather.
Temperatures across the eastern half of continent shot up. Boston and Buffalo both climbed above 70 degrees Fahrenheit, their hottest February temperatures ever measured. Washington, D.C., posted a string of summery days and will likely tally its warmest February ever. Cincinnati came close to breaking 80.
This capped off a weird winter. For the first time since modern record-keeping began in 1871, Chicago made it through January and February without any snow on the ground. Hot, dry air from the Mexican plateau handed a 94-degree day to Oklahoma City and an 80-degree day to Denver. And while the West experienced more typical coolness, historic amounts of rain and snow ensnarled California. Ski resorts in the Sierra Nevadas measured more than 500 inches of snow, breaking half-century-old records.
For most of the country, those unseasonably warm temperatures mean that the seasons themselves will arrive somewhat unseasonably. Trees and flowers will probably bloom much earlier this year: Some forecasters believe that the famous cherry blossoms in Washington, D.C., will flower before March 15, two and a half weeks earlier than the average.
Data from the U.S. Geological Survey shows that spring has already overtaken most of the American south. In this map, deep maroon represents areas where the spring bloom has started 20 days earlier than normal:
This can prompt excitement (if you’re sick of winter) or apprehension (if you suffer from allergies). But it can also prompt wonder and worry at what it all means. Doesn’t it feel like plants bloom earlier and earlier every year? When spring arrives a month early, does it have a cost?
The answer, say climate scientists, is yes and yes. Thanks to human-caused climate change, spring is happening about 2.5 days earlier every decade. But to understand the deeper meaning and damage of that change, it’s worth first asking: What makes spring spring?
* * *
For people who live between the tropics and the Arctic Circle, spring is two different phenomena that happen at the same time. The first is that the weather gets warmer: Daily high temperatures rise, nights stop getting so cold, and eventually frost no longer forms on the ground. The second is a natural renewal: plants bloom and grow, migratory birds and insects return, and many animals give birth or hatch. The study of this second event—and the other cycles of nature’s calendar—is called phenology.
Usually, these two events happen in concert: The warmer days of meteorological spring arrive in March or April, and phenological spring follows. But when the weather goes awry, it can confound the fine-tuned mechanisms of biology. So when scientists talk about spring getting earlier, they’re really asking two different questions: Has meteorological spring been happening differently or earlier in the year? And has that changed phenological spring?
“Spring is coming earlier,” says Jake Weltzin, executive director of the U.S. National Phenological Network. “But it depends on where you are.”
No matter how you measure it, meteorological spring is arriving earlier and earlier. Across the Northern Hemisphere, the first warmth of early spring arrives about a day earlier every decade. The last cold days get earlier and earlier as well. A recent study found that more than three-quarters of U.S. national parks experience an earlier spring than they did a century ago, and more than half of them are on the “extreme” side of that shift.
This is, in turn, triggering an earlier phenological spring. A 2006 analysis found that, on average, trees now leaf out about a day earlier than they did the decade before. And in most parts of the country, the agricultural growing season begins at least a week earlier now than it did in the 1960s.
Seasonal shift may sound methodical: Can’t farmers just assume that the growing season gets steadily earlier every year? But they can’t. Seasonal changes—which unfold predictably on decadal scales—are difficult to forecast from year to year. One year, cherry blossoms might bloom three weeks earlier than the average; the next, they might bloom a week later. The blooming season creeps earlier and earlier, but it does so erratically.
Weltzin says that this has high costs for tourism, for agriculture, and for ecology. Any town or region trying to organize an outdoor festival must now reckon with the new seasonal calendar.
“The Great Smoky Mountains has a firefly festival, where they have synchronous fireflies,” he told me. “Only a few places in the world have synchronous fireflies, so they have to plan ahead for weeks to think about how to manage the traffic on narrow backroads. The Park Service stretches to get out ahead of the issue,” but it struggles to do so when spring is so unpredictable, he said.
What’s destructive is that not all facets of meteorological spring are uniformly moving earlier. Some are staying the same. In many places in the United States, the date of the last frost of the year isn’t moving much at all. David Inouye, a biologist at the University of Maryland, has found that the last frost date in some parts of the Rockies has stayed put at June 10, even as warmth arrives earlier in the season.
Many wildflowers begin their growing season in late May, as the snow melts, he told me in an email. By the time these flowers have sprouted frost-sensitive buds a month later, the chilling season is over.
“But now sometimes snow melts in mid-April and by June there are a lot of plants with flowers and buds, and some of those are frost-sensitive. Most or all of the frost-sensitive flowers don’t bloom in years like that. And if the flowers are killed by frost, there is then no nectar or pollen for pollinators, and no seeds for animals that eat them,” he added.
“In some parts of the country, the timing of the last frost isn’t getting earlier as fast as the growing season,” said Mark D. Schwartz, a professor of geography at the University of Wisconsin Milwaukee. This is dependent on a number of local factors, but it proved especially damaging in 2012, when North America experienced the earliest “false spring” in the weather record.
These kinds of mismatches can upset complex relationships between animals and their environment. In the Arctic, some grasses bloom a month before normal, depriving hibernating animals of a crucial early-spring food source. Snowshoe hares turn white during the winter, and then brown during the summer, so that they can be better camouflaged against the ground. But now that snow is melting earlier in the year, many are still wearing their white coats in the spring mud—making them especially easy for predators to pick off.
These kind of seasonal mismatches are best documented in the Arctic, but researchers are increasingly finding them elsewhere. “When we look, we find evidence. But it’s patchy,” says Weltzin. Scientists are hampered by the lack of good long-term databases capturing multiple seasonal variables. The birding database Ebird is an extremely useful phenological database, for instance. It’s high-quality despite being managed by amateur birders. But it doesn’t tell scientists about the local availability of insects, seeds, or nectar.
Not all plants are subject to the whims of an early meteorological spring. While many grasses, flowers, and shrubs—like honeysuckle and lilac—bloom only in response to temperature, other plants wait for more certain signals.
The hardwood trees that dominate Eastern forests—oak, beech, and hackberry—all need to experience the longer days of astronomical spring before they begin to flower. (Astronomical spring begins this year on March 20, the vernal equinox.) These hardwoods are also the species most protected from a late frost: They can’t be fooled just by a false spring’s warmth; they also need the light of axial tilt. Researchers write that even when these sturdy trees are planted well south of their natural range, in subtropical climates where they could flourish in January or February, they still seek the light signal and never bloom before early March.
Often when people talk about climate change, they talk about how the world will change in the future. But an early spring is happening now. The same study that revealed how national parks are facing seasonal shift included a special warning for park rangers: “Managers who have worked in these parks for the past one to three decades are already working under anomalous conditions.”
But that warning applies many of us: The springs of the past 30 years have been “anomalous.” The national parks are not the only thing that have already changed. The natural calendar that guides all of our lives has already changed, too.
We want to hear what you think. Submit a letter to the editor or write to firstname.lastname@example.org. | <urn:uuid:4da83a04-8d59-4b6b-bca8-ef27fa22d61a> | 3.578125 | 1,931 | News Article | Science & Tech. | 53.710127 | 95,517,542 |
Python, code, examples - Learn, python by, example
Loads(data) return True except ValueError as error: print invalid json: s" error) return False " #Valid json Data "actors "actor "id "1 "firstName "Tom "lastName "Cruise" #Invalid json Data "actor "id "1 "firstName "Tom "lastName "Cruise" " prints True print #prints Error message and False. Loads method is used to validate json data.
Python - Converting Float to Dollars and Cents - Stack Overflow
Within the function Money, we assign Money a value, therefore Python assumes Money as a local variable. ' Forces the field to be centered within the available space. Leaving out the argument to most_common produces a list of all the items, in order of frequency.
Python - Stack Overflow
(Did you note what symbols were in the machine language. ModuleN, when the interpreter encounters an import statement, it imports the module if the module is present in the search path.
How to make money with, python - Quora
If a local and a global variable have the same name, the local variable shadows the global variable. So there is a "printf" in Python? Many Ways for a Nicer Output. print The value.format(x) The value is 78,962,324,245 print The value is 0:6,d".format(x) The value is 5,897,653,423.89676 print The value is 0:12,.3f".format(x) The value is 5,897,653,423.897 ' Forces the padding to be placed after the sign (if any) but before the digits.
Acoobe / python-money, bitbucket
They are prefixed with an 'f'. Here are a few examples: # Prints out 0,1,2,3,4 and then it prints "count value reached 5" count0 while(count 5 print(count) count 1 else: print count value reached d" (count) # Prints out 1,2,3,4 for i in range(1, 10 if(i50 break print(i) else: print this. ' f"Price in Swiss Franks: price *.086:5.2f" 'Price in Swiss Franks:.20' for article in "bread "butter "tea. it may be followed by zero or more keyword arguments of the form namevalue. | <urn:uuid:4ee95066-4378-4302-9eb7-0604293338db> | 3.890625 | 525 | Content Listing | Software Dev. | 72.518643 | 95,517,588 |
Protein labeling is used by researchers in a variety of fields to help them understand how these important molecules affect the normal functioning of cells. Currently, proteins are labeled for study simply by fusing them to other fluorescent proteins, which allows researchers to use microscopy to track their movements through a cell. This approach has several drawbacks, however, not least being that the fluorescent proteins are often large enough to affect the function of the protein of interest.
Dr. Alex Deiters, associate professor of chemistry, along with colleague Dr. Jason Chin of the Laboratory of Molecular Biology at the Medical Research Council in Cambridge, U.K., have developed a way to attach a fluorophore – a fluorescent molecule about 20 times smaller than the fluorescent proteins currently in use – to a protein that is expressed in a mammalian cell.
Deiters and Chin developed a special 21st amino acid that they added to cells that were specially engineered to incorporate this amino acid into the protein they wanted to study (there are normally only 20 amino acids). This 21st amino acid has a “chemical handle” that only reacts with a specifically designed fluorophore, but not any cellular components. According to Deiters, “The reaction between the modified protein and the fluorophore is extremely fast, high yielding, and generates a stable link between both reaction partners. This novel methodology enables future cell biological studies that were previously not possible.”
The research appears in the Feb. 5 issue of Nature Chemistry.
“We found that our approach gave us a higher yield of labeled proteins and that the binding reaction was 50 times faster than with current methods,” Deiters says. “Additionally, it took less reagent to complete the reaction, so overall we have a faster, more efficient method for protein labeling, and less chance of interfering with the normal function of the proteins and cells being studied.”
The research was funded by the National Institutes of Health and the National Science Foundation. The Department of Chemistry is part of NC State’s College of Physical and Mathematical Sciences.
Note to editors: Abstract of the paper follows“Genetically encoded norbornene directs site-specific cellular protein labelling via a
rapid bioorthogonal reaction”
Authors: Alexander Deiters, Jessica Torres-Kolbus, Chungjung Chou, North Carolina State University; Jason W. Chin, Kathrin Lang, Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge, UK
Published: Feb. 5, 2012 in Nature ChemistryAbstract:
Tracey Peake | Newswise Science News
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
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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...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
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In my probability class I was tackled with this seemingly weird question involving conditional expectation:
Let X,Y be two random variables (it is not mentioned whether or not they are discrete or continuous) and we are asked the following:
For all constants $ \beta $ we have $ E[X | Y = \beta] = E[X] $
- Version of Conditional Expectation
- Computing the expectation of conditional variance in 2 ways
- $X = E(Y | \sigma(X)) $ and $Y = E(X | \sigma(Y))$
- Is conditional expectation with respect to two sigma algebra exchangeable?
- sign of the conditional expectation
- If $E(X\mid Y)=Z$, $E(Y\mid Z)=X$ and $E(Z\mid X)=Y$, then $X=Y=Z$ almost surely
$ cov(X,Y) = E[XY]-E[X]E[Y] = 0 $
The problem: we are asked to prove or give a counterexample to 1 leads to 2 and to 2 leads to 1
I have tried to prove these two directions but got nothing just by looking at the definitions and so I thought maybe they are false and we are to give counterexamples but I got nothing there either. Looking at the covariance formula I see Y is involved but I cannot really seem to incorporate it from conditional expectation given, so I am stuck and need help. Thanks to all. | <urn:uuid:25575ffc-a24a-4060-ba69-1fc84574bb61> | 2.578125 | 317 | Q&A Forum | Science & Tech. | 25.968983 | 95,517,629 |
It is still beyond human beings' ability to fully comprehend the dynamical and radiative processes behind the climate change. With satellite remote sensing data, we are somewhat provided a chance to take a sneak peek of what a long-term, consistent and robust climate data record would look like. Satellites have kept sending back data from the space for decades, and these data tell stories about this blue planet we all dwell in.
"There's something, something about this place."
- Lady Gaga
As a PhD student at the department of earth and atmospheric sciences of Indiana University in Bloomington, I work with Dr. Staten on the topic of climate variability and clouds using satellite data from legacy instruments such as AVHRR and HIRS. We use a unique method to combine AVHRR cloud type radiance and HIRS spectral data together, in order to create a spectrally resolved dataset. An example of the data we're looking at is shown below. My previous research includes retrieval of optical thickness of maritime stratocumulus with satellite data, sensitivity study of properties that could influence the retrieval of smoke aerosol, radiative transfer models and processing and visualization of satellite data from multiple sensors (AVHRR, MODIS, VIIRS, OMI, CALIPSO, etc) flown on A-train satellites.
I enjoy using different programming tools to visualize my data. Previously I used IDL solely for both computational and visulizational purpose. Now I am gradually migrating my codes and scripts to Python to fully utilize the advantage of xarray to process netCDF files.
Correlation between Cirrus Cloud Frequency and MEI This map shows the correlation between cirrus cloud frequency (CF) measured by AVHRR on-board MetOp A satellite for the time period from 2009 to 2016 and multi-variate ENSO index (MEI). A clear positive correlation of cirrus CF in the tropical region indicates a increase of cirrus associated with El Nino episodes.
I am an associate instructor (AI) for
For Python workshop day 2, the Jupyter notes can be found here | <urn:uuid:ae53584a-6b98-4546-828f-28373510e0e6> | 2.546875 | 431 | About (Pers.) | Science & Tech. | 27.694902 | 95,517,633 |
Professor Alfred McEwen, HiRISE’s Principal Investigator, will be highlighting some of the most recent results at the European Planetary Science Congress in Münster on Wednesday 24th September.
A study of the nature and distribution of ancient megabreccia, led by McEwen at the University of Arizona, suggests that this bedrock was formed during the late heavy bombardment period. Megabreccia consists of angular, randomly-orientated blocks that formed suddenly in energetic events such as meteorite impacts. It is thought to contain fragments of the oldest and deepest bedrock exposed on the surface of Mars.
“We think that the megabreccia was formed during a period of heightened meteorite activity about 3.9 billion years ago. This is around the time life appears to have begun on Earth, but we have very little record of that era in our terrestrial geology because ancient rocks are heavily metamorphosed. Mars preserves a much better record of the heavy bombardment and, unlike the dry lunar surface, it shows the environmental effects in a water-rich crust,” said McEwen.
The HiRISE team has identified megabreccia in more than 50 locations consistent with the most ancient terrains on Mars. These include the central uplifts of large craters and deep exposures such as the floor of parts of Valles Marineris. Well-exposed rock outcrops are needed to identify megabreccia, in particular from the diversity of colours and textures indicating diverse rock types.
Megabreccia contains rock fragments from the earliest geological period on Mars, the Noachian era, which is more than 3.8 billion years ago.
The megabreccia blocks vary in size from relatively small (1-5 metres) to larger than 10 metres in diameter. The blocks are cemented in a matrix of finer material. The small blocks were probably formed by post Noachian cratering, particularly when found in material filling crater floors. The large blocks are only found in locations consistent with hard, deep bedrock, such as the central uplifts. McEwen suggests that the blocks are largely cemented by melt from impacts and hydrothermal alteration.
“We are in the midst of a paradigm shift in understanding the Noachian crust of Mars, thanks to the high-resolution data from the Mars Express and MRO missions. The spectrometers on these missions found evidence of alteration due to water in the bedrock in many, if not most Noachian aged places. However, the younger Noachian era may have been relatively dry, so we may need to study the oldest outcrops of megabreccia to understand this era.”
McEwen will also be presenting results of processes that may be shaping the surface of Mars today. A study led by Dr Alexandra Lefort, a researcher in the team of Professor Nicolas Thomas of the University of Bern, has shown that scallop-shaped features found in mid-latitudes on Mars are likely to be formed by the sublimation of shallow ice.
HiRISE imagery shows the scallops have steep polar-facing scaps and gentle equatorial-facing rises. Groups of scallops appear to be separated by areas of knobbly ground. Lefort and colleagues studied scallops in the western part of a region called Utopia Planitia, between 40-55 degrees north.
Lefort said, “We have developed a model where a small hummock on the landscape becomes warmer on the equatorial-facing side. As the fraction of ice in the subsurface sublimates, the ground slumps leaving an asymmetric scallop-shaped hollow. The equatorial-facing slope continues to erode, lengthening out the shape. Near the polar-facing scarp, the depression is deepest and coldest and the underlying ice is most stable. Higher ice concentrations near the scarp leads to the development of a fine network of polygonal-shaped cracks across the floor and this may make the scarp more fragile and prone to landslides. Eventually, neighbouring scallops can coalesce”
Large parts of the mid and high-latitudes of Mars are covered by an erosion-resistant mantle deposit perhaps metres thick in places. This layer consists of ice and dust, with concentrations equivalent to around 4 percent water at 40 degree latitudes, ranging to 20 percent water at 60 degree latitudes. It is unclear as yet whether the scallops form in the ice-rich mantle or in ground that is rich in ice due to some other process
Unlike Earth, Mars has a significant variation in the angle at which its rotational axis is tilted relative to the plane of its orbital axis, known as its obliquity. Over periods of tens of millions of years, this angle can vary from nearly vertical to almost 60 degrees. Models have shown that ice is most stable at lower latitudes during periods of high obliquity. The axis of Mars is currently tilted at an angle of 25.2 degrees, an intermediate obliquity, which means that it is possible that these scallop-forming erosion processes are continuing today.
Dr Kathryn Fishbaugh presented results suggesting that the presence of thick, erosion resistant layers called marker beds, which are found at regular intervals through the north polar layered deposits, are linked to changes caused by periodic fluctuations in the planet’s orbital orientation.
The marker beds are separated by 20-30 metres and are 5-10 metres thick, without any evidence of finer-scale layering within them. This suggests that they have either been deposited quickly or that a coating layer is shrouding evidence of fine layering. Between the marker beds are thinner layers with a thickness of a metre or less.
Fishbaugh and colleagues have found an intriguing resonance between the ratio of marker beds to fine layers (20,30:1) and the ratio of the orbital inclination to the precessional period of Mars’s axis (23:1).
“From our observations, it looks like marker beds are formed on Mars when its orbit is relatively flat with respect to the equatorial plane and its axis is relatively upright. But this makes it hard to explain why these layers are so tough. It’s easier to explain the resistance to erosion of they were formed during periods of high obliquity. With more observations, we hope to answer this question.”
Anita Heward | alfa
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Earth Sciences
19.07.2018 | Power and Electrical Engineering
19.07.2018 | Materials Sciences | <urn:uuid:c4e617db-b68c-49a3-a24f-77927bdeccfe> | 3.765625 | 1,966 | Content Listing | Science & Tech. | 42.068646 | 95,517,643 |
Differential Geometry: Lecture Notes
by Dmitri Zaitsev
Publisher: Trinity College Dublin 2004
Number of pages: 49
From the table of contents: Chapter 1. Introduction to Smooth Manifolds; Chapter 2. Basic results from Differential Topology; Chapter 3. Tangent spaces and tensor calculus; Tensors and differential forms; Chapter 4. Riemannian geometry.
Download or read it online for free here:
by Nigel Hitchin
The historical driving force of the theory of manifolds was General Relativity, where the manifold is four-dimensional spacetime, wormholes and all. This text is occupied with the theory of differential forms and the exterior derivative.
by Matt Visser - Victoria University of Wellington
In this text the author presents an overview of differential geometry. Topics covered: Topological Manifolds and differentiable structure; Tangent and cotangent spaces; Fibre bundles; Geodesics and connexions; Riemann curvature; etc.
by John Edward Campbell - Clarendon Press
Contents: Tensor theory; The ground form when n=2; Geodesics in two-way space; Two-way space as a locus in Euclidean space; Deformation of a surface and congruences; Curves in Euclidean space and on a surface; The ruled surface; Minimal surface; etc.
by Gabriel Lugo - University of North Carolina at Wilmington
These notes were developed as a supplement to a course on Differential Geometry at the advanced undergraduate level, which the author has taught. This texts has an early introduction to differential forms and their applications to Physics. | <urn:uuid:37471997-dd9a-4c97-8d17-b8f5a119ee5b> | 2.8125 | 345 | Content Listing | Science & Tech. | 24.286842 | 95,517,684 |