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The SCUBA images. These images show massive galaxies caught in the throes of formation. The stars are forming so rapidly that an entire galaxy can be built in a short timescale (cosmologically speaking, so a billion years or so). The star formation in these galaxies is thought to be driven by mergers of older galaxies in a filamentary structure spanning millions of light years. In billions of years time, this structure is predicted to become a cluster of giant elliptical galaxies similar to those we see today in the local Universe.
From left to right and top to bottom the images are centred on the following radio galaxies: 4C41.17, 4C60.07, 8C1435+635, 8C1909+722, B3J2330+3927 and PKS1138-262.
Revealing images produced by one of the world’s most sophisticated telescopes are enabling a team of Edinburgh astronomers to see clearly for the first time how distant galaxies were formed 12 billion years ago. Scientists from the UK Astronomy Technology Centre (UK ATC) and the University of Edinburgh have been targeting the biggest and most distant galaxies in the Universe with the world’s most sensitive submillimetre camera, SCUBA. The camera, built in Edinburgh, is operated on the James Clerk Maxwell Telescope in Hawaii. The images, published in Nature tomorrow (18 September), reveal prodigious amounts of dust-enshrouded star formation which could ultimately tell scientists more about the formation of our own galaxy.
It is thought these distant galaxies in the early Universe will evolve into the most massive elliptical galaxies seen at the present day. These giant galaxies consist of 1000 billion stars like our Sun and are found in large groups or clusters.
Dr Jason Stevens, astronomer at the UK ATC in Edinburgh explained why understanding the evolution of these galaxies is so important. "The distant, youthful Universe was a very different place to the one we inhabit today. Billions of years ago, massive galaxies are thought to have formed in spectacular bursts of star formation. These massive elliptical galaxies have relatively simple properties. We hope that by understanding how simple galaxies form we will be one step closer to understanding how our own, spiral, Milky Way galaxy formed".
Julia Maddock | 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:64d3eb3d-4697-4132-a1b9-8d179fa11ca1> | 3.546875 | 1,045 | Content Listing | Science & Tech. | 39.094934 | 95,491,544 |
Marine reserves give a boost to coral reefs
A new study by University of Exeter researchers has found that marine reserves not only protect the fish that live in them, but may also help improve the health of coral reefs.india Updated: Jan 09, 2006 11:57 IST
A new study by University of Exeter researchers has found that marine reserves not only protect the fish that live in them, but may also help improve the health of coral reefs.
According to the study, published in the journal Science, the researchers looked at how a marine park in the Bahamas was affected by the return of the reef's top predator, the Nassau Grouper.
They were concerned that an increase in groupers could have an adverse effect, because they feed on parrotfish which play a vital role in maintaining the reef ecosystem. “More than 20 years ago sea urchins in the Caribbean were wiped out by disease, leaving parrotfish as the main grazer of reef surfaces.
The fish use their teeth to remove seaweed from the reef which allows new corals to settle and grow,” said lead researchers Peter Mumby.
“This grazing process is essential to the health of the system. Caribbean reefs are still trying to recover from the devastating effects of an El Nino bleaching event in 1998 which caused widespread damage to coral around the world,” Mumby added. The researchers found that marine reserves might provide exactly the right conditions to allow this to happen. | <urn:uuid:3f25ce27-1e8b-4f8d-ac8d-812045088db2> | 3.078125 | 304 | Truncated | Science & Tech. | 43.096756 | 95,491,558 |
Extreme Global Warming Fix Proposed: Fill the Skies With Sulfur
for National Geographic News
August 4, 2006
A Nobel Prize-winning scientist has proposed a controversial method for protecting Earth from global warming: seeding the atmosphere with sulfur to reflect the sun's rays.
In the current issue of the journal Climate Change, Paul Crutzen of Germany's Max Planck Institute for Chemistry suggests injecting particles of sulfur into the stratosphere—the upper layer of the atmosphere—to cool the planet and buy time for humans to reduce greenhouse gas emissions.
The sulfur particles would be dropped from high-altitude balloons or fired into the atmosphere with heavy artillery shells, he says.
Once airborne the particles would act like tiny mirrors, bouncing the sun's light and heat back into space.
Crutzen's plan would imitate the cooling effects of volcanic eruptions, which send large sulfur-rich clouds into the atmosphere.
When Mount Pinatubo in the Philippines erupted in 1991, he points out, the huge plume of sulfur cooled the Earth by 0.9 degree Fahrenheit (0.5 degree Celsius) the following year.
A relatively small amount of sulfate could produce a level of cooling similar to that caused by the Pinatubo eruption, according to Crutzen's calculations.
Crutzen, who won the Nobel Prize in Chemistry in 1995 for his work on the ozone layer, stresses that it is still important for nations to cut back greenhouse gas emissions, but extreme measures like this may be necessary to provide more time.
"I hope that my experiment will never have to take place," he said in an email.
This isn't the first time
that scientists have suggested meddling with Earth's climate in order to reduce
the impact of global warming.
"All of us recognize that geo-engineering seems increasingly likely to be the only route to staving off a cataclysm in the short term before new, clean energy sources are developed sufficiently," Latham said.
He thinks that Crutzen's idea is feasible, but he says further investigation is needed.
"This idea could help to hold the temperature constant, but we need to examine some of the potential adverse ramifications," Latham said.
Crutzen admits that there is a risk of the sulfur becoming a health hazard if it rained back down on Earth.
In addition there could be an increase in damage to the ozone layer and a whitening of the sky.
"If things go wrong during the experiment, then [we would] stop," he said. "In a few years the atmosphere [will] return back to its earlier condition."
On the upside, sunsets and sunrises would become more spectacular.
Crutzen calculates that launching enough sulfate to have an effect for two years would cost between 25 billion and 50 billion U.S. dollars, about $25 to $50 per head in the developed world.
There may still be time for nations to reduce greenhouse emissions enough to make such extreme measures unnecessary, Crutzen concludes, but no one can know for certain.
"We don't know the future, so this question is impossible to answer," he said.
© 2006 Chemtrails911.com, All rights reserved. | <urn:uuid:b697910f-022b-4ffa-ae03-8d1ff09a7779> | 3.75 | 666 | News Article | Science & Tech. | 48.184929 | 95,491,561 |
Scientists at Harvard Medical School have cleared up some of the mystery surrounding a key structure in the developing brain that helps form the visual circuits. Their findings, which appear in the July 25 issue of Science, could provide new insight into early brain defects that are linked to conditions like cerebral palsy and learning disabilities.
During development, nerve cells in the eye send messages to the thalamus, a region located deep within the brain. The thalamus then passes these messages on to the area of the outer cerebral cortex that deals with vision. The connection between the thalamus and cortex initially passes through a transient and seldom studied structure called the subplate. By removing parts of the subplate in cats, the HMS researchers have shown that this structure is a key component in strengthening the thalamus to cortex connection and in mapping out further cortical wiring patterns important for vision.
The subplate neurons are acting "kind of like teachers," says senior author Carla Shatz, the Nathan Marsh Pusey professor of neurobiology and head of the HMS Department of Neurobiology. "Theyre needed for the thalamic connections to strengthen and grow so that they can become strong enough to talk to the cortical neurons."
John Lacey | EurekAlert!
Innovative genetic tests for children with developmental disorders and epilepsy
11.07.2018 | Christian-Albrechts-Universität zu Kiel
Oxygen loss in the coastal Baltic Sea is “unprecedentedly severe”
05.07.2018 | European Geosciences Union
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Transportation and Logistics
16.07.2018 | Agricultural and Forestry Science | <urn:uuid:3a00ef25-a935-4b2b-a3f3-c057f33e0480> | 3.328125 | 904 | Content Listing | Science & Tech. | 39.652596 | 95,491,571 |
However, given the vastness of space and the long times between supernovae, astronomers can say with certainty that there is no threatening star close enough to hurt Earth.
Supernova 1987A was the closest exploding star seen in modern times. It occurred in the Large Magellanic Cloud, a small galaxy that orbits our own Milky Way. Images taken by NASA's Hubble Space Telescope were combined to make this composite of the blast's expanding debris. Credit: Credit: NASA / ESA / P. Challis and R. Kirshner (Harvard-Smithsonian Center for Astrophysics)
Astronomers estimate that, on average, about one or two supernovae explode each century in our galaxy. But for Earth's ozone layer to experience damage from a supernova, the blast must occur less than 50 light-years away. All of the nearby stars capable of going supernova are much farther than this.
Any planet with life on it near a star that goes supernova would indeed experience problems. X- and gamma-ray radiation from the supernova could damage the ozone layer, which protects us from harmful ultraviolet light in the sun's rays. The less ozone there is, the more UV light reaches the surface. At some wavelengths, just a 10 percent increase in ground-level UV can be lethal to some organisms, including phytoplankton near the ocean surface. Because these organisms form the basis of oxygen production on Earth and the marine food chain, any significant disruption to them could cascade into a planet-wide problem.
Another explosive event, called a gamma-ray burst (GRB), is often associated with supernovae. When a massive star collapses on itself -- or, less frequently, when two compact neutron stars collide -- the result is the birth of a black hole. As matter falls toward a nascent black hole, some of it becomes accelerated into a particle jet so powerful that it can drill its way completely through the star before the star's outermost layers even have begun to collapse. If one of the jets happens to be directed toward Earth, orbiting satellites detect a burst of highly energetic gamma rays somewhere in the sky. These bursts occur almost daily and are so powerful that they can be seen across billions of light-years.
A gamma-ray burst could affect Earth in much the same way as a supernova -- and at much greater distance -- but only if its jet is directly pointed our way. Astronomers estimate that a gamma-ray burst could affect Earth from up to 10,000 light-years away with each separated by about 15 million years, on average. So far, the closest burst on record, known as GRB 031203, was 1.3 billion light-years away.
As with impacts, our planet likely has already experienced such events over its long history, but there's no reason to expect a gamma-ray burst in our galaxy to occur in the near future, much less in December 2012.
Susan Hendrix | EurekAlert!
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
Theorists publish highest-precision prediction of muon magnetic anomaly
16.07.2018 | DOE/Brookhaven National Laboratory
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 | Transportation and Logistics
16.07.2018 | Agricultural and Forestry Science | <urn:uuid:641bff47-8183-462f-acf1-46e32015d6bb> | 4.40625 | 1,257 | Content Listing | Science & Tech. | 44.219049 | 95,491,572 |
2NO(g) + O2(g) 2NO2(g)
Given that we start with 0.036M NO(g) and 0.036M O2(g) AND end with 0.014M NO2, what is the equilibrium constant for this reaction and what are the equilibrium concentrations for NO and O2?
Find the best study resources around, tagged to your specific courses. Share your own to gain free Course Hero access.
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A consequence of the law of conservation of energy is that a perpetual motion machine of the first kind cannot exist. That is to say, no system without an external energy supply can deliver an unlimited amount of energy to its surroundings.
Ancientphilosophers as far back as Thales of Miletus c.550 BCE had inklings of the conservation of some underlying substance of which everything is made. However, there is no particular reason to identify this with what we know today as "mass-energy" (for example, Thales thought it was water). Empedocles (490–430 BCE) wrote that in his universal system, composed of four roots (earth, air, water, fire), "nothing comes to be or perishes"; instead, these elements suffer continual rearrangement.
A local conservation law is usually expressed mathematically as a continuity equation, a partial differential equation which gives a relation between the amount of the quantity and the "transport" of that quantity. It states that the amount of the conserved quantity at a point or within a volume can only change by the amount of the quantity which flows in or out of the volume. | <urn:uuid:bf357eea-9ab1-45eb-8427-c67ecc377391> | 3.34375 | 235 | Knowledge Article | Science & Tech. | 34.049153 | 95,491,609 |
Plasmid Metagenomes in Activated Sludge
Plasmid metagenomes in activated sludge refers to all the genetic material on plasmids in the microorganisms present in the activated sludge.
Activated sludge (AS) is a high-efficiency and low-cost biological wastewater treatment process which is being widely used to remove pollutants in wastewater. Plasmids often play important roles in shaping the microbial characteristics of activated sludge, such as the antibiotic resistance, which is just a hotspot that many researchers have already studied on (Yang et al. 2012; Zhang et al. 2011) and contribute to multiple important functions of activated sludge, such as degradation of refractory organic pollutants and transformation of heavy metals. Additionally, in the system of AS, plasmids always have high levels of genetic diversity and composition (Schluter et al. 2008). Therefore, the analysis of plasmids has a significance in characterizing microbial populations in activated sludge and understanding the...
KeywordsActivate Sludge Lateral Gene Transfer Sludge Floc Important Ecological Function Activate Sludge Floc
- Barkay T, Smets BF. Horizontal gene flow in microbial communities. ASM News. 2005;71:412–9.Google Scholar | <urn:uuid:fe36f3a9-6341-4c24-b72c-345be125dd69> | 2.609375 | 259 | Academic Writing | Science & Tech. | 21.878315 | 95,491,631 |
All materials are made up of atoms, which vibrate. These vibrations, or 'phonons', are responsible, for example, for how electric charge and heat is transported in materials. Vibrations of metals, semiconductors, and insulators in are well studied; however, now materials are being nanosized to bring better performance to applications such as displays, sensors, batteries, and catalytic membranes. What happens to vibrations when a material is nanosized has until now not been understood.
Soft Surfaces Vibrate Strongly
Researchers at ETH have shown for the first time what happens to atomic vibrations when materials are nanosized and how this knowledge can be used to systematically engineer nanomaterials for different applications. Using both experiment, simulation, and theory, they explain how and why vibriations at the surface of a nanomaterial (q) can interact strongly with electrons (k and k').
Credit: Deniz Bozyigit / ETH Zurich
In a recent publication in Nature, ETH Professor Vanessa Wood and her colleagues explain what happens to atomic vibrations when materials are nanosized and how this knowledge can be used to systematically engineer nanomaterials for different applications.
The paper shows that when materials are made smaller than about 10 to 20 nanometers -- that is, 5,000 times thinner than a human air -- the vibrations of the outermost atomic layers on surface of the nanoparticle are large and play an important role in how this material behaves.
"For some applications, like catalysis, thermoelectrics, or superconductivity, these large vibrations may be good, but for other applications like LEDs or solar cells, these vibrations are undesirable," explains Wood.
Indeed, the paper explains why nanoparticle-based solar cells have until now not met their full promise. The researchers showed using both experiment and theory that surface vibrations interact with electrons to reduce the photocurrent in solar cells.
"Now that we have proven that surface vibrations are important, we can systematically design materials to suppress or enhance these vibrations," say Wood.
Improving Solar Cells
Wood's research group has worked for a long time on a particular type of nanomaterial -- colloidal nanocrystals -- semiconductors with a diameter of 2 to 10 nanometers. These materials are interesting because their optical and electrical properties are dependent on their size, which can be easily changed during their synthesis.
These materials are now used commercially as red- and green-light emitters in LED-based TVs and are being explored as possible materials for low cost, solution-processed solar cells. Researchers have noticed that placing certain atoms around the surface of the nanocrystal can improve the performance of solar cells. The reason why this worked had not been understood. The work published in the Nature paper now gives the answer: a hard shell of atoms can suppress the vibrations and their interaction with electrons. This means a higher photocurrent and a higher efficiency solar cell.
Big Science to Study the Nanoscale
Experiments were conducted in Professor Wood's labs at ETH Zurich and at the Swiss Spallation Neutron Source at the Paul Scherrer Institute. By observing how neutrons scatter off atoms in a material, it is possible to quantify how atoms in a material vibrate. To understand the neutron measurements, simulations of the atomic vibrations were run at the Swiss National Supercomputing Center (CSCS) in Lugano. Wood says, "without access to these large facilities, this work would not have been possible. We are incredibly fortunate here in Switzerland to have these world class facilities."
Bozyigit D et al. Soft surfaces of nanomaterials enable strong phonon interactions. Nature, Advanced Online Publication, March 09, 2016. DOI: 10.1038/nature16977
Prof. Vanessa Wood | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Materials Sciences
20.07.2018 | Physics and Astronomy
20.07.2018 | Materials Sciences | <urn:uuid:f7e2b2b4-6af0-4e96-98e0-4cd8201a1dab> | 3.9375 | 1,358 | Content Listing | Science & Tech. | 32.970279 | 95,491,635 |
What are the physiological challenges an organism (such as a waterbug) might experience in a freshwater lake of the following conditions: depth of 200 m, water cold (approx 10 degrees celcius on surface), eutrophic, poor visibility, pH approx. 4?© BrainMass Inc. brainmass.com July 21, 2018, 6:03 am ad1c9bdddf
What are the physiological challenges an organism (such as a waterbug) might experience in a freshwater lake of the following conditions: depth of 200 m, water cold (approx 10 degrees Celsius on surface), eutrophic, poor visibility, pH approx. 4?
The key to answering this question is to think about the stresses that these conditions would put on an aquatic insect. These stressors could be things that decrease the organism's ability to capture prey or escape from predators or things that alter the organism's homeostasis. Let's look at each condition separately:
Freshwater: When an organism lives in water osmosis and ion transfer is going to occur between the external environment and the organism's cells, until the two environments are isotonic (same concentration of water and ions inside and out). Most organisms' cells can only operate correctly and/or survive in a limited range of osmolarities. When exposed to external conditions not appropriate to their cells they can do a few things: 1. move, 2. osmoregulate (usually through ionic pumps), 3. become isotonic with the environment and deal with it. To address this question specifically you want to find out the osmotic requirements of the waterbug. It is likely that its cells are isotonic to freshwater and then there would be no osmotic and ionic stress, however if there was a ...
In this solution I describe how/why each condition could (depth, temperature, eutrophic level, pH, and visibility) physiologically stresses a waterbug, including definitions of terms and physiological theory. | <urn:uuid:40bec14f-0b90-4068-b66f-44b9eed29e70> | 3.25 | 404 | Truncated | Science & Tech. | 42.634997 | 95,491,643 |
The TRMM satellite is operated by the Japanese Space Agency and NASA, and continually monitors the tropics and measures rainfall in tropical cyclones. TRMM captured an early morning look at the forming depression on June 16, 2011 at 2130 UTC (5:30 p.m. EDT). A precipitation analysis from TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) showed that Tropical Depression 06W wasn't well organized but contained areas of moderate to heavy rainfall located east of the Philippines.
The heaviest rainfall appears on the northwestern and southeastern areas of the depression. Most of the rainfall is moderate falling at a rate between .78 to 1.57 inches (20 and 40 mm) per hour. The isolated areas of heavy rain over ocean areas are falling at about 2 inches (50 mm) per hour.
The Philippines have already received a lot of rain from tropical cyclones this season. Tropical storm Aere, Super Typhoon Songda and Tropical Storm Sarika have already affected the Philippines this year.
Now, Tropical Depression 06W threatens even more rainfall. On June 17 at 1500 UTC (11 a.m. EDT) Tropical Depression 06W had maximum sustained winds near 25 knots. It was located about 430 nautical miles east-southeast of Manila, Philippines near 12.1 North and 127.6 East. It was moving to the northwest near 13 knots.
Tropical Depression 06W is expected to intensify to a tropical storm, skirt the eastern coast of the Philippines and head toward Taiwan over the next five days. During the middle part of the week of June 19, Tropical Depression 06W is expected to make landfall in southeastern China.
Rob Gutro | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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Is there anyone out there? Better build a bigger telescopeUpdated: October 21, 2013 10:14am
Scientists are tantalizingly close to answering the question of whether there's life out there.
After discovering thousands of planets around other stars, including more than a dozen Earth-size worlds upon which there could be oceans of water, astronomers are beginning to know where to look to find signs of life.
Now, they just need enough money to construct the right instrument.
At present, a flurry of telescope construction is occurring on Earth, including three efforts to build the largest ground-based telescope. One of these, the Giant Magellan Telescope, is being developed in part by Texas A&M and the University of Texas. There's also NASA's James Webb Space Telescope, a successor to the Hubble Space Telescope, that's planned for a 2018 launch.
But none of these telescopes, each of which costs at least $1 billion, are likely to find life on distant planets.
"We'd have to get very lucky," said Sara Seager, an exoplanet scientist at the Massachusetts Institute of Technology.
It may take a still more advanced super telescope to find just the right planet, with just the right atmosphere.
Signs of life
Through devices such as television and radio humans emit a lot of electromagnetic radiation. The SETI project, or search for extraterrestrial intelligence, for decades has used radio telescopes to search the heavens for these kinds of artificial signals. So far they've found none.
To find life, astronomers believe, they need to look in distant planetary atmospheres.
If they could find the right combination of oxygen, methane and other molecules likely to result from bacteria, plants or animals, scientists would have a smoking gun for life.
The next generation of ground-based telescopes will be two to three times larger than the biggest optical telescopes, at Keck Observatory in Hawaii, which have 33-foot mirrors. These new telescopes, in conjunction with the Webb space telescope, have an outside chance of making such an observation.
Seager said there may be about 10 planets around smaller stars near to Earth that, if they supported life, the Webb could find the telltale signs.
She and other scientists, therefore, are considering what might come after Webb.
For these post-Webb discussions, size matters. The bigger the mirror in space, the more nearby planets astronomers will be able to scrutinize. Of course bigger mirrors are also more expensive to build and launch.
One of the most audacious ideas is the ATLAST project, a plan to build a space telescope made of several mirrors to add up to a 50-foot mirror. The Hubble space telescope has an eight-foot mirror. Given the cost overruns with Hubble and now Webb, currently projected to cost in excess of $8 billion, finding public and political support for such a large, multi-billion-dollar telescope could be challenging.
"It's very hard," admitted Matt Mountain, director of the Space Telescope Science Institute, which operates the science program for the Hubble and will do the same for the Webb telescope.
"The question is, what's Plan B for the human spaceflight program, once you've built a Hubble and a Webb? What's the next step for breakthroughs? What inspires people to do great things? Well, great ideas."
The ATLAST telescope would be able to scan thousands of planets near Earth. If none showed signs of life, that would say something pretty profound about the existence of life on Earth. Finding life elsewhere would be profound as well.
Unifying space missions
Building such a telescope may sound like an unrecognizable dream for cash-strapped NASA, but Mountain said its development would nicely complement the agency's human spaceflight program.
Only the large, heavy lift rocket NASA is currently developing would have the capability to launch the mirror segments needed for the telescope, he said. And it would require astronauts to assemble the telescope in orbit before flying it away from Earth to a location where it could make observations.
The resulting partnership could unify NASA's separate exploration and science missions together, Mountain said.
There are other ideas. One of them is the Colossus Telescope, a ground-based instrument that would be on the order of two or three times larger than the Magellan and other next-generation telescopes now under construction.
Unlike SETI's search for radio waves, the proposed Colossus Telescope would search for heat signals from other worlds, specifically something akin to the urban heat islands created by very large cities on Earth.
The big drawback, again, is the price of a telescope that would surely cost billions of dollars.
"This is without doubt one of the most ambitious and out-of-the-box projects" in the field of ground telescopes, said Franck Marchis, a planetary astronomer at the SETI Institute. "The challenge is enormous with the design of a low-weight thin membrane telescope but also the search for funding."
Most astronomers agree that addressing the question of life elsewhere in the universe is one of the most important questions science can now begin to address. Few dispute its cultural appeal. Some astronomers however, think the public and private appetite for ever larger telescopes may become saturated as the prices of super telescopes get bigger and bigger.
"From my point of view as an older person, these young people who have great visions, all the best to the them," said David Lambert, director of the University of Texas' McDonald Observatory. "I think the advances are going to come from clever ideas that have manageable costs." | <urn:uuid:035b623d-b90b-4f21-aad3-ae4faba28775> | 3.296875 | 1,134 | Truncated | Science & Tech. | 42.11263 | 95,491,697 |
Thousands of scientists from more than 60 countries will be conducting research during this two-year programme. IPY 2007-2008 will be an intense, internationally coordinated campaign of polar observations, interdisciplinary research and analysis that will enhance our understanding of physical, biological and social processes in the polar regions, examine their globally-connected role in the climate system, and set the stage for assessments, forecasts, recommendations, and future discovery.
Because of the remoteness and harshness of the polar regions, in situ research is very difficult to carry out and has proved to be insufficient for comprehensive studies. For the first time during an International Polar Year, the scientific community has at its disposal satellite measurements offering broad coverage of the polar regions and thus opening up new scientific possibilities.
The last International Polar Year was in 1957-1958 and provided the foundation for much of the polar science knowledge we have today. Given the important role polar regions play for global change, there is now more than ever a need for a coordinated international initiative to achieve a major advance in polar science and in the understanding of the Earth's climate and ecosystems.
For more than 20 years, ESA has been providing increasing support to the cryosphere communities in the form of satellite data. Since the early 1990s, ESA has been able to provide near-continuous satellite data on these regions over long periods of time. Continuous data are essential for scientists to identify and analyse long-term climatic trends and changes.
During IPY 2007-2008, ESA will make its legacy data available through an extensive Earth observation data portfolio containing current and historical data (dating back 15 years) from its ERS 1, ERS 2 and Envisat satellites, as well as data collected from a number of non-ESA satellites.
Moreover, during this two-year period, ESA has committed to helping scientists collect an increasing amount of satellite information, particularly to understand recent and current distributions and variations in snow and ice. ESA satellite data – images, microwave data, and even sensitive gravity measurements – will be used to try to understand changes in the global ice sheets.
For this purpose, ESA issued, at the end of 2006, a dedicated Announcement of Opportunity for EO data provision for scientific research and application development in support of IPY 2007-2008, with data provision to start in spring 2007. All the data will be free of charge, and the 48 selected projects from 12 different countries will cover both the Arctic and Antarctic regions.
Data will be made available, and the exploitation of historical archives possible, in connection with the following missions: ESA’s Envisat, ERS 1 and 2, Proba, GOCE and SMOS (when ready), and third-party missions including Japan’s ALOS and the CNES, French Space Agency, Spot-4.
In 2009, when this IPY comes to an end, ESA will make another significant contribution to research in the polar regions with the launch of Cryosat 2. This spacecraft will monitor precise changes in the thickness of the polar ice sheets and floating sea ice. The observations made over the three-year lifetime of the mission will provide conclusive evidence on the rates at which ice cover is diminishing.
Another initiative that began in 2006 and is supported by ESA is Polar View. This is a satellite remote-sensing programme, funded through the Earthwatch GMES Service Element (GSE) and focused on both the Arctic and the Antarctic. It promotes the utilisation of satellites for the public good and in support of public policy, in the areas of sustainable economic development, marine safety, and the environment.
Polar View delivers services to stakeholder groups interested in issues relating to those three areas in the polar regions. These groups include policy-makers, government departments, northern residents, and public agencies. Polar View also collaborates with the national ice centres to generate and provide expanded and more detailed information sets. In addition, Polar View provides information for certain private customers and commercial interests, such as iceberg information for yacht races around the Antarctic and for hunters and trappers travelling and working in the North.
Background to International Polar Years
IPY 2007-2008 aims to enhance international collaboration in polar region research and monitoring, link researchers across different fields to address questions and issues lying beyond the scope of individual disciplines, ensure data collected under the IPY are made available in an open and timely manner and intensify the recovery of relevant historical data and ensure these also are made openly available.
There have been three IPYs over the last 125 years – 1882-1883, 1932-1933 and 1957-1958. Scientific and exploration programmes that have arisen out of each IPY have led to scientific advancements, new discoveries and greater understanding of many geophysical phenomena that influence the Earth’s global systems.
IPY 2007-2008 is being co-sponsored by the International Council for Science (ICSU) and the World Meteorological Organisation (WMO) and is endorsed by 31 nations. The idea of IPY was inspired by the Austrian explorer Karl Weyprecht, who was a scientist and co-commander of the Austro-Hungarian Polar Expedition of 1872-74.
Mark Drinkwater | alfa
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
Drones survey African wildlife
11.07.2018 | Schweizerischer Nationalfonds SNF
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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NASA is forging ahead with plans to make water, oxygen, and hydrogen on the surface of the Moon and Mars.
If we ever want to colonize other planets, it is vital that we find a way of extracting these vital gases and liquids from moons and planets, rather than transporting them from Earth.
The current plan is to land a rover on the Moon in 2018 that will try to extract hydrogen, water, and oxygen — and then hopefully, Curiosity’s successor will try to convert the carbon dioxide in the atmosphere into oxygen in 2020 when it lands on Mars.
In 2018, NASA hopes to put a rover on the Moon that will carry the RESOLVE (Regolith and Environment Science and Oxygen & Lunar Volatile Extraction) science payload.
RESOLVE will contain the various tools necessary to carry out in-situ resource utilization (ISRU).
Basically, RESOLVE will sift through the Moon’s regolith (loose surface soil) and heat them up, looking for traces of hydrogen and oxygen, which can then be combined to make water.
There is also some evidence that there’s water ice on the surface of the Moon — RESOLVE will find out for certain by heating the soil and seeing of water vapor emerges.
A similar payload would be attached to Curiosity’s successor, which is currently being specced out by NASA and will hopefully launch in 2020.
This second IRSU experiment will probably suck in carbon dioxide from the Martian atmosphere, filter out the dust, and then process the CO2 into oxygen.
If either tech demonstration works as planned, future missions might include large-scale ISRU devices that are capable of producing significant amounts of hydrogen, oxygen, and water on the Moon or Mars.
This would probably be the most important advance since we first landed on the Moon in the ’60s. Basically, as it stands, space travel needs lots of hydrogen and oxygen and water.
Water has the unfortunate characteristic of being both heavy and incompressible, meaning it’s very difficult and expensive to lift large amounts of it into space (gravity can be really annoying sometimes).
Likewise, unless we come up with some other way of powering our spacecraft, it’s infeasible to carry the rocket fuel that we’d need for exploration from Earth.
In short, if we want to colonize space, we really, really need some kind of base outside of the Earth’s atmosphere, preferably on the Moon — but Mars would be good, too.
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BioelectromagneticsWikipedia Open wikipedia design.
Bioelectromagnetics, also known as bioelectromagnetism, is the study of the interaction between electromagnetic fields and biological entities. Areas of study include electrical or electromagnetic fields produced by living cells, tissues or organisms, including bioluminescent bacteria; for example, the cell membrane potential and the electric currents that flow in nerves and muscles, as a result of action potentials. Others include animal navigation utilizing the geomagnetic field; the effects of man-made sources of electromagnetic fields like mobile phones; and developing new therapies to treat various conditions. The term can also refer to the ability of living cells, tissues, and organisms to produce electrical fields and the response of cells to electromagnetic fields.
Short-lived electrical events called action potentials occur in several types of animal cells which are called excitable cells, a category of cell include neurons, muscle cells, and endocrine cells, as well as in some plant cells. These action potentials are used to facilitate inter-cellular communication and activate intracellular processes. The physiological phenomena of action potentials are possible because voltage-gated ion channels allow the resting potential caused by electrochemical gradient on either side of a cell membrane to resolve.
Bioelectromagnetism is studied primarily through the techniques of electrophysiology. In the late eighteenth century, the Italian physician and physicist Luigi Galvani first recorded the phenomenon while dissecting a frog at a table where he had been conducting experiments with static electricity. Galvani coined the term animal electricity to describe the phenomenon, while contemporaries labeled it galvanism. Galvani and contemporaries regarded muscle activation as resulting from an electrical fluid or substance in the nerves.
Some usually aquatic animals, such as sharks, have acute bioelectric sensors providing a sense known as electroreception, while migratory birds navigate in part by orienteering with respect to the Earth's magnetic field. In an extreme application of electromagnetism the electric eel is able to generate a large electric field outside its body used for hunting and self-defense through a dedicated electric organ.
Most of the molecules in the human body interact weakly with electromagnetic fields in the radio frequency or extremely low frequency bands. One such interaction is absorption of energy from the fields, which can cause tissue to heat up; more intense fields will produce greater heating. This can lead to biological effects ranging from muscle relaxation (as produced by a diathermy device) to burns. Many nations and regulatory bodies like the International Commission on Non-Ionizing Radiation Protection have established safety guidelines to limit EMF exposure to a non-thermal level. This can be defined as either heating only to the point where the excess heat can be dissipated, or as a fixed increase in temperature not detectable with current instruments like 0.1 °C. However, biological effects have been shown to be present for these non-thermal exposures; Various mechanisms have been proposed to explain these, and there may be several mechanisms underlying the differing phenomena observed. Biological effects of weak electromagnetic fields are the subject of study in magnetobiology.
Many behavioral effects at different intensities have been reported from exposure to magnetic fields, particularly with pulsed magnetic fields. The specific pulseform used appears to be an important factor for the behavioural effect seen; for example, a pulsed magnetic field originally designed for spectroscopic MRI, referred to as Low Field Magnetic Stimulation, was found to temporarily improve patient-reported mood in bipolar patients, while another MRI pulse had no effect. A whole-body exposure to a pulsed magnetic field was found to alter standing balance and pain perception in other studies.
A strong changing magnetic field can induce electrical currents in conductive tissue such as the brain. Since the magnetic field penetrates tissue, it can be generated outside of the head to induce currents within, causing transcranial magnetic stimulation (TMS). These currents depolarize neurons in a selected part of the brain, leading to changes in the patterns of neural activity. In repeated pulse TMS therapy or rTMS, the presence of incompatible EEG electrodes can result in electrode heating and, in severe cases, skin burns. A number of scientists and clinicians are attempting to use TMS to replace electroconvulsive therapy (ECT) to treat disorders such as severe depression. Instead of one strong electric shock through the head as in ECT, a large number of relatively weak pulses are delivered in TMS therapy, typically at the rate of about 10 pulses per second. If very strong pulses at a rapid rate are delivered to the brain, the induced currents can cause convulsions much like in the original electroconvulsive therapy. Sometimes, this is done deliberately in order to treat depression, such as in ECT.
While health effects from extremely low frequency (ELF) electric and magnetic fields (0 to 300 Hz) generated by power lines, and radio/microwave frequencies (RF) (10 MHz - 300 GHz) emitted by radio antennas and wireless networks have been well studied, the intermediate range (IR) used increasingly in modern telecommunications (300 Hz to 10 MHz) has been studied far less. Direct effects of electromagnetism on human health have been difficult to prove, and documented life-threatening interferences from electromagnetic fields are limited to medical devices such as pacemakers and other electronic implants. However, a number of studies have been conducted with artificial magnetic fields and electric fields to investigate their effects on cell metabolism, apoptosis, and tumor growth.
Electromagnetic radiation in the intermediate frequency range has found a place in modern medical practice for the treatment of bone healing and for nerve stimulation and regeneration. It is also approved as cancer therapy in form of Tumor Treating Fields, using alternating electric fields in the frequency range of 100–300 kHz. Since some of these methods involve magnetic fields that invoke electric currents in biological tissues and others only involve electric fields, they are strictly speaking electrotherapies albeit their application modi with modern electronic equipment have placed them in the category of bioelectromagnetic interactions.
- Electric fish
- Electrical brain stimulation
- Electromagnetic radiation and health
- Kirlian photography
- Michael Persinger
- Mobile phone radiation and health
- Specific absorption rate
- Transcutaneous electrical nerve stimulation
- Tumor Treating Fields
- Malmivuo, Jaakko; Plonsey, Robert (1994). Bioelectromagnetism: principles and applications of bioelectric and biomagnetic fields. New York: Oxford University Press. ISBN 978-0-19-505823-9.[page needed]
- Myers, Richard (2003). The basics of chemistry. Westport, Conn.: Greenwood Press. pp. 172–4. ISBN 978-0-313-31664-7.
- "Hazards of the MR Environment". Martinos Center for Biomedical Imaging. Retrieved 19 March 2013.
- Binhi, 2002
- Rohan, Michael; Parow, Aimee; Stoll, Andrew L; Demopulos, Christina; Friedman, Seth; Dager, Stephen; Hennen, John; Cohen, Bruce M; Renshaw, Perry F (2004). "Low-Field Magnetic Stimulation in Bipolar Depression Using an MRI-Based Stimulator". American Journal of Psychiatry. 161 (1): 93–8. doi:10.1176/appi.ajp.161.1.93. PMID 14702256.
- Thomas, A.W; White, K.P; Drost, D.J; Cook, C.M; Prato, F.S (2001). "A comparison of rheumatoid arthritis and fibromyalgia patients and healthy controls exposed to a pulsed (200 μT) magnetic field: effects on normal standing balance". Neuroscience Letters. 309 (1): 17–20. doi:10.1016/S0304-3940(01)02009-2.
- Shupak, Naomi M; Prato, Frank S; Thomas, Alex W (2004). "Human exposure to a specific pulsed magnetic field: effects on thermal sensory and pain thresholds". Neuroscience Letters. 363 (2): 157–162. doi:10.1016/j.neulet.2004.03.069. PMID 15172106.
- Roth, Bradley J; Pascual-Leone, Alvaro; Cohen, Leonardo G; Hallett, Mark (1992). "The heating of metal electrodes during rapid-rate magnetic stimulation: A possible safety hazard". Electroencephalography and Clinical Neurophysiology/Evoked Potentials Section. 85 (2): 116–23. doi:10.1016/0168-5597(92)90077-O. PMID 1373364.
- Wassermann, Eric M (1998). "Risk and safety of repetitive transcranial magnetic stimulation: Report and suggested guidelines from the International Workshop on the Safety of Repetitive Transcranial Magnetic Stimulation, June 5–7, 1996". Electroencephalography and Clinical Neurophysiology/Evoked Potentials Section. 108 (1): 1–16. doi:10.1016/S0168-5597(97)00096-8. PMID 9474057.
- Rossi, Simone; Hallett, Mark; Rossini, Paolo M; Pascual-Leone, Alvaro (2009). "Safety, ethical considerations, and application guidelines for the use of transcranial magnetic stimulation in clinical practice and research". Clinical Neurophysiology. 120 (12): 2008–39. doi:10.1016/j.clinph.2009.08.016. PMC . PMID 19833552.
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- Shahin, Saba; Banerjee, Somanshu; Singh, Surya Pal; Chaturvedi, Chandra Mohini (2015). "2.45 GHz Microwave Radiation Impairs Learning and Spatial Memory via Oxidative/Nitrosative Stress Induced p53-Dependent/Independent Hippocampal Apoptosis: Molecular Basis and Underlying Mechanism". Toxicological Sciences. 148 (2): 380–99. doi:10.1093/toxsci/kfv205. PMID 26396154.
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- The Bioelectromagnetics Society (BEMS)
- European BioElectromagnetics Association (EBEA)
- Society for Physical Regulation in Biology and Medicine (SPRBM) (formerly the Bioelectrical Repair and Growth Society, BRAGS)
- International Society for Bioelectromagnetism (ISBEM)
- The Bioelectromagnetics Lab at University College Cork, Ireland
- Institute of Bioelectromagnetism
- Vanderbilt University, Living State Physics Group, archived page
- Ragnar Granit Institute.
- Institute of Photonics and Electronics AS CR, Department of Bioelectrodynamics.
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- Becker, Robert O.; The Body Electric: Electromagnetism and the Foundation of Life, William Morrow & Co, 1985. ISBN 0-688-00123-8.
- Becker, Robert O.; Cross Currents: The Promise of Electromedicine, the Perils of Electropollution, Tarcher, 1989. ISBN 0-87477-536-1.
- Binhi, V.N., Magnetobiology: Underlying Physical Problems. San Diego: Academic Press, 2002. ISBN 0-12-100071-0.
- Brodeur Paul; Currents of Death, Simon & Schuster, 2000. ISBN 0-7432-1308-4.
- Carpenter, David O.; Sinerik Ayrapetyan, Biological Effects of Electric and Magnetic Fields, Volume 1 : Sources and Mechanisms, Academic Press, 1994. ISBN 0-12-160261-3.
- Carpenter, David O.; Sinerik Ayrapetyan, Biological Effects of Electric and Magnetic Fields : Beneficial and Harmful Effects (Vol 2), Academic Press, 1994. ISBN 0-12-160261-3.
- Chiabrera A. (Editor), Interactions Between Electromagnetic Fields and Cells, Springer, 1985. ISBN 0-306-42083-X.
- Habash, Riadh W. Y.; Electromagnetic Fields and Radiation: Human Bioeffects and Safety, Marcel Dekker, 2001. ISBN 0-8247-0677-3.
- Horton William F.; Saul Goldberg, Power Frequency Magnetic Fields and Public Health, CRC Press, 1995. ISBN 0-8493-9420-1.
- Mae-Wan, Ho; et al., Bioelectrodynamics and Biocommunication, World Scientific, 1994. ISBN 981-02-1665-3.
- Malmivuo, Jaakko; Robert Plonsey, Bioelectromagnetism: Principles and Applications of Bioelectric and Biomagnetic Fields, Oxford University Press, 1995. ISBN 0-19-505823-2.
- O'Connor, Mary E. (Editor), et al., Emerging Electromagnetic Medicine, Springer, 1990. ISBN 0-387-97224-2.
- European Biophysics Journal
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- Radiatsionnaya Bioliogiya Radioecologia ("Radiation Biology and Radioecology", in Russian) (ISSN 0869-8031) | <urn:uuid:30e80064-e181-467c-b3d6-78f180f3f906> | 3.40625 | 3,112 | Knowledge Article | Science & Tech. | 38.841019 | 95,491,732 |
NAMEhier - Description of the file system hierarchy
DESCRIPTIONA typical Linux system has, among others, the following directories: / This is the root directory. This is where the whole tree starts. /bin This directory contains executable programs which are needed in single user mode and to bring the system up or repair it. /boot Contains static files for the boot loader. This directory only holds the files which are needed during the boot process. The map installer and configuration files should go to /sbin and /etc. /dev Special or device files, which refer to physical devices. See mknod(1). /etc Contains configuration files which are local to the machine. Some larger software packages, like X11, can have their own subdirectories below /etc. Site-wide configuration files may be placed here or in /usr/etc. Nevertheless, programs should always look for these files in /etc and you may have links for these files to /usr/etc. /etc/opt Host-specific configuration files for add-on applications installed in /opt. /etc/sgml This directory contains the configuration files for SGML and XML (optional). /etc/skel When a new user account is created, files from this directory are usually copied into the user's home directory. /etc/X11 Configuration files for the X11 window system (optional). /home On machines with home directories for users, these are usually beneath this directory, directly or not. The structure of this directory depends on local administration decisions. /lib This directory should hold those shared libraries that are necessary to boot the system and to run the commands in the root file system. /media This directory contains mount points for removable media such as CD and DVD disks or USB sticks. /mnt This directory is a mount point for a temporarily mounted file system. In some distributions, /mnt contains subdirectories intended to be used as mount points for several temporary file systems. /opt This directory should contain add-on packages that contain static files. /proc This is a mount point for the proc file system, which provides information about running processes and the kernel. This pseudo-file system is described in more detail in proc(5). /root This directory is usually the home directory for the root user (optional). /sbin Like /bin, this directory holds commands needed to boot the system, but which are usually not executed by normal users. /srv This directory contains site-specific data that is served by this system. /tmp This directory contains temporary files which may be deleted with no notice, such as by a regular job or at system boot up. /usr This directory is usually mounted from a separate partition. It should hold only sharable, read-only data, so that it can be mounted by various machines running Linux. /usr/X11R6 The X-Window system, version 11 release 6 (optional). /usr/X11R6/bin Binaries which belong to the X-Window system; often, there is a symbolic link from the more traditional /usr/bin/X11 to here. /usr/X11R6/lib Data files associated with the X-Window system. /usr/X11R6/lib/X11 These contain miscellaneous files needed to run X; Often, there is a symbolic link from /usr/lib/X11 to this directory. /usr/X11R6/include/X11 Contains include files needed for compiling programs using the X11 window system. Often, there is a symbolic link from /usr/include/X11 to this directory. /usr/bin This is the primary directory for executable programs. Most programs executed by normal users which are not needed for booting or for repairing the system and which are not installed locally should be placed in this directory. /usr/bin/X11 is the traditional place to look for X11 executables; on Linux, it usually is a symbolic link to /usr/X11R6/bin. /usr/dict Replaced by /usr/share/dict. /usr/doc Replaced by /usr/share/doc. /usr/etc Site-wide configuration files to be shared between several machines may be stored in this directory. However, commands should always reference those files using the /etc directory. Links from files in /etc should point to the appropriate files in /usr/etc. /usr/games Binaries for games and educational programs (optional). /usr/include Include files for the C compiler. /usr/include/X11 Include files for the C compiler and the X-Window system. This is usually a symbolic link to /usr/X11R6/include/X11. /usr/include/asm Include files which declare some assembler functions. This used to be a symbolic link to /usr/src/linux/include/asm. /usr/include/linux This contains information which may change from system release to system release and used to be a symbolic link to /usr/src/linux/include/linux to get at operating system specific information. (Note that one should have include files there that work correctly with the current libc and in user space. However, Linux kernel source is not designed to be used with user programs and does not know anything about the libc you are using. It is very likely that things will break if you let /usr/include/asm and /usr/include/linux point at a random kernel tree. Debian systems don't do this and use headers from a known good kernel version, provided in the libc*-dev package.) /usr/include/g++ Include files to use with the GNU C++ compiler. /usr/lib Object libraries, including dynamic libraries, plus some executables which usually are not invoked directly. More complicated programs may have whole subdirectories there. /usr/lib/X11 The usual place for data files associated with X programs, and configuration files for the X system itself. On Linux, it usually is a symbolic link to /usr/X11R6/lib/X11. /usr/lib/gcc-lib contains executables and include files for the GNU C compiler, gcc(1). /usr/lib/groff Files for the GNU groff document formatting system. /usr/lib/uucp Files for uucp(1). /usr/local This is where programs which are local to the site typically go. /usr/local/bin Binaries for programs local to the site. /usr/local/doc Local documentation. /usr/local/etc Configuration files associated with locally installed programs. /usr/local/games Binaries for locally installed games. /usr/local/lib Files associated with locally installed programs. /usr/local/include Header files for the local C compiler. /usr/local/info Info pages associated with locally installed programs. /usr/local/man Man pages associated with locally installed programs. /usr/local/sbin Locally installed programs for system administration. /usr/local/share Local application data that can be shared among different architectures of the same OS. /usr/local/src Source code for locally installed software. /usr/man Replaced by /usr/share/man. /usr/sbin This directory contains program binaries for system administration which are not essential for the boot process, for mounting /usr, or for system repair. /usr/share This directory contains subdirectories with specific application data, that can be shared among different architectures of the same OS. Often one finds stuff here that used to live in /usr/doc or /usr/lib or /usr/man. /usr/share/dict Contains the word lists used by spell checkers. /usr/share/doc Documentation about installed programs. /usr/share/games Static data files for games in /usr/games. /usr/share/info Info pages go here. /usr/share/locale Locale information goes here. /usr/share/man Manual pages go here in subdirectories according to the man page sections. /usr/share/man/<locale>/man[1-9] These directories contain manual pages for the specific locale in source code form. Systems which use a unique language and code set for all manual pages may omit the <locale> substring. /usr/share/misc Miscellaneous data that can be shared among different architectures of the same OS. /usr/share/nls The message catalogs for native language support go here. /usr/share/sgml Files for SGML and XML. /usr/share/terminfo The database for terminfo. /usr/share/tmac Troff macros that are not distributed with groff. /usr/share/zoneinfo Files for timezone information. /usr/src Source files for different parts of the system, included with some packages for reference purposes. Don't work here with your own projects, as files below /usr should be read-only except when installing software. /usr/src/linux This was the traditional place for the kernel source. Some distributions put here the source for the default kernel they ship. You should probably use another directory when building your own kernel. /usr/tmp Obsolete. This should be a link to /var/tmp. This link is present only for compatibility reasons and shouldn't be used. /var This directory contains files which may change in size, such as spool and log files. /var/adm This directory is superseded by /var/log and should be a symbolic link to /var/log. /var/backups Reserved for historical reasons. /var/cache Data cached for programs. /var/catman/cat[1-9] or /var/cache/man/cat[1-9] These directories contain preformatted manual pages according to their man page section. (The use of preformatted manual pages is deprecated.) /var/cron Reserved for historical reasons. /var/lib Variable state information for programs. /var/local Variable data for /usr/local. /var/lock Lock files are placed in this directory. The naming convention for device lock files is LCK..<device> where <device> is the device's name in the file system. The format used is that of HDU UUCP lock files, that is, lock files contain a PID as a 10-byte ASCII decimal number, followed by a newline character. /var/log Miscellaneous log files. /var/opt Variable data for /opt. /var/mail Users' mailboxes. Replaces /var/spool/mail. /var/msgs Reserved for historical reasons. /var/preserve Reserved for historical reasons. /var/run Run-time variable files, like files holding process identifiers (PIDs) and logged user information (utmp). Files in this directory are usually cleared when the system boots. /var/spool Spooled (or queued) files for various programs. /var/spool/at Spooled jobs for at(1). /var/spool/cron Spooled jobs for cron(8). /var/spool/lpd Spooled files for printing. /var/spool/mail Replaced by /var/mail. /var/spool/mqueue Queued outgoing mail. /var/spool/news Spool directory for news. /var/spool/rwho Spooled files for rwhod(8). /var/spool/smail Spooled files for the smail(1) mail delivery program. /var/spool/uucp Spooled files for uucp(1). /var/tmp Like /tmp, this directory holds temporary files stored for an unspecified duration. /var/yp Database files for NIS.
CONFORMING TOThe Filesystem Hierarchy Standard, Version 2.2 <//www.pathname.com/fhs/>.
BUGSThis list is not exhaustive; different systems may be configured differently.
SEE ALSOfind(1), ln(1), proc(5), mount(8) The Filesystem Hierarchy Standard
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/. HIER(7) | <urn:uuid:c0f75fdc-65c9-4cde-aa50-ca690f7f62ca> | 3.625 | 2,594 | Documentation | Software Dev. | 52.549696 | 95,491,736 |
The UI Model is used to describe the various components of an application's User Interface. This model is an abstract definition that is rendered into reality on a particular platform through the use of a presentation engine driving a set of renderers (usually but not limited to one renderer part UI Model type.
The model itself is based on EMF. One of the things that EMF does a really good job at is allowing multiple inheritance so the basic design of the model starts with low-level components that can then be aggregated into concrete classes.
The model itself is composed from a number of different type of elements which are used to define the 'concrete' UI elements (i.e. the ones that actually get rendered):
Used to contain the attributes for different concepts such as label information or containment types. These will be useful when we eventually start to derive domain-specific models based on the current one.
In order to facilitate the use of Java generics each container may only contain elements of a single 'type' (interface really). These elements represent the type that is legal in a given container. In order to make an element legal for a given container add that container's type as one of the mix-ins for the class being contained.
WindowElement - Elements that can be added to a Window's list of children:
TrimElement - Elements that can be added to a TrimBar
PartSashContainerElement - Elements that can be added to a PartSashContainer
- PartSashContainer (it's recursive)
StackElement - Elements that can be added to a PartStack
These define the true UI model as used to present an applicaton. The UI Model has been broken down into a number of discreet packages, the sections below will be based on the contents of each package:
This package contains the most elementary of the UI components:
MTrimBar (contained by an MTrimmedWindow but not in its list of children)
Basic UI (Descriptors)
This Package contains the 'descriptors' for various elements. Currently only PartDescriptors are supported but over time we may well want to include other types such as PerspectiveDescriptors. Essentially this is the e4 way to capture the set of available views that a user may wish to open and from which the actual MPart can be instantiated.
This package contains the elements necessary to support more complex UI's such as are required by the Eclipse IDE itself such as Perspectives and (editor) Areas.
This package contains the elements necessary to support the Commands infrastructure. Here a single command is referenced by any number of Handlers (at most one of which will be active in any given UI context.
MBindingTable Not sure we want this as API for now since we may want to combine or modify how these are used
- While these are related to MBindingContext, they're not the same thing. These are flat tables of keybindings that are used for lookups. Pwebster.ca.ibm.com
MParameter Do we need this ?
- This is used when placing a command in a menu item or keybinding, to specify the parameter (ex: Show View(Package Explorer). Pwebster.ca.ibm.com
Menus (and Toolbars)
This package contains the elements used to define menus, toolbars and their corresponding items. There are two flavors for the items, 'direct' and 'handled' based on wether the item is backed by a Command or not.
MMenuContribution This appears as if it should be part of the snippet story
- This is a candidate for snippets if 1) we use the EMF XPath support (org.eclipse.e4.emf.xpath) to specify where they are placed and 2) the snippets are re-evaluated every time a new object is added to the model (we would have to be worried about performance). Pwebster.ca.ibm.com
MOpaqueMenu This is unnecessary (we can use different renderes for a standard MMenu now)
- This might be replaceable with a tag. It's a placeholder for a Menu that the compatibility layer creates (and so it needs to be recognized by the renderer but not under its control). Pwebster.ca.ibm.com
MOpaqueMenuItem This is unecessary
MOpaqueMenuSeparator This is unnecessary
MOpaqueToolItem This is unnecessary
MPopupMenu Do we need this...why does a popup menu need a context ?
- Yes, we need a specialized menu that participates in the context hierarchy. A popup menu is like a child of the part it belongs to, it fills in specialized variable and state that need to be available to any commands executed from it. Pwebster.ca.ibm.com
MRenderedMenu This is unnecessary
- This generates an SWT Menu by delegating to an IMenuCreator from the action world (via an IContextFunction). Maybe it could be replaced with a new renderer. Pwebster.ca.ibm.com
MRenderedMenuItem This is unnecessary
MRenderedToolbar This is unnecessary
MToolBarContribution This appears as if it should be part of the snippet story
MTrimContribution This appears as if it should be part of the snippet story | <urn:uuid:81cc0d95-a19f-40f8-95ff-74ebd4fcf66f> | 3.15625 | 1,118 | Documentation | Software Dev. | 43.478653 | 95,491,749 |
In mathematics, a Ford circle is a circle with center at and radius where is an irreducible fraction, i.e. and are coprime integers. Each Ford circle is tangent to the horizontal axis and any two Ford circles are either tangent or disjoint from each other.
Ford circles are a special case of mutually tangent circles; the base line can be thought of as a circle with infinite radius. Systems of mutually tangent circles were studied by Apollonius of Perga, after whom the problem of Apollonius and the Apollonian gasket are named. In the 17th century René Descartes discovered Descartes' theorem, a relationship between the reciprocals of the radii of mutually tangent circles.
Ford circles also appear in the Sangaku (geometrical puzzles) of Japanese mathematics. A typical problem, which is presented on an 1824 tablet in the Gunma Prefecture, covers the relationship of three touching circles with a common tangent. Given the size of the two outer large circles, what is the size of the small circle between them? The answer is equivalent to a Ford circle:
The Ford circle associated with the fraction is denoted by or There is a Ford circle associated with every rational number. In addition, the line is counted as a Ford circle – it can be thought of as the Ford circle associated with infinity, which is the case
Two different Ford circles are either disjoint or tangent to one another. No two interiors of Ford circles intersect, even though there is a Ford circle tangent to the x-axis at each point on it with rational coordinates. If is between 0 and 1, the Ford circles that are tangent to can be described variously as
- the circles where
- the circles associated with the fractions that are the neighbors of in some Farey sequence, or
- the circles where is the next larger or the next smaller ancestor to in the Stern–Brocot tree or where is the next larger or next smaller ancestor to .
If and are two tangent Ford circles, then the circle through and (the x-coordinates of the centers of the Ford circles) and that is perpendicular to the -axis (whose center is on the x-axis) also passes through the point where the two circles are tangent to one another.
By interpreting the upper half of the complex plane as a model of the hyperbolic plane (the Poincaré half-plane model) Ford circles can be interpreted as horocycles. In hyperbolic geometry any two horocycles are congruent . When these horocycles are circumscribed by apeirogons they tile the hyperbolic plane with an order-3 apeirogonal tiling.
Total area of Ford circles
There is a link between the area of Ford circles, Euler's totient function the Riemann zeta function and Apéry's constant As no two Ford circles intersect, it follows immediately that the total area of the Ford circles
is less than 1. In fact the total area of these Ford circles is given by a convergent sum, which can be evaluated. From the definition, the area is
Simplifying this expression gives
Note that as a matter of convention, the previous calculations excluded the "trivial" circle of radius corresponding to the fraction .
- Apollonian gasket – a fractal with infinite mutually tangential circles in a circle instead of on a line
- Ford, L. R. (1938), "Fractions", The American Mathematical Monthly, 45 (9): 586–601, doi:10.2307/2302799, JSTOR 2302799, MR 1524411.
- Coxeter, H. S. M. (1968), "The problem of Apollonius", The American Mathematical Monthly, 75: 5–15, doi:10.2307/2315097, MR 0230204.
- Fukagawa, Hidetosi; Pedoe, Dan (1989), Japanese temple geometry problems, Winnipeg, MB: Charles Babbage Research Centre, ISBN 0-919611-21-4, MR 1044556.
- Graham, Ronald L.; Lagarias, Jeffrey C.; Mallows, Colin L.; Wilks, Allan R.; Yan, Catherine H. (2003), "Apollonian circle packings: number theory", Journal of Number Theory, 100 (1): 1–45, arXiv: , doi:10.1016/S0022-314X(03)00015-5, MR 1971245.
- Marszalek, Wieslaw (2012), "Circuits with oscillatory hierarchical Farey sequences and fractal properties", Circuits, Systems and Signal Processing, 31 (4): 1279–1296, doi:10.1007/s00034-012-9392-3. | <urn:uuid:c7e6cb2d-9e60-47bd-a7ed-ef1f0369d7b1> | 3.78125 | 1,027 | Knowledge Article | Science & Tech. | 55.712941 | 95,491,762 |
A View from Emerging Technology from the arXiv
China Reveals Solar Sail Plan To Prevent Apophis Hitting Earth in 2036
A small shove could prevent a global catastrophe, according to Chinese plans
Apophis is a 46 million tonne asteroid that will pass within a hair’s breath of Earth in 2029. However, Apophis’s trajectory is likely to take it through a region of space near Earth known as a keyhole that will ensure the asteroid returns in 2036.
Nobody knows how close Apophis will come on that pass. But if there’s a chance of a collision, we’ll have only 7 years to work out how to avoid catastrophe.
Today, Shengping Gong and pals at Tsinghua University in Beijing say they’ve come up with a plan that will ensure Apophis never returns to Earth on this timescale .
They point out that keyholes are tiny, in this case just 600 metres wide. So deflecting Apophis by only a small amount in the near future will ensure it misses the keyhole and so cannot return to Earth.
There are various ways to deflect an asteroid. Gong and pals say their preference is to use a solar sail to place a small spacecraft into a retrograde orbit and on collision course with Apophis. The retrograde orbit will give it an impact velocity of 90km/s which, if they do this well enough in advance, should lead to a collision large enough to do the trick.
Putting a spacecraft into a retrograde orbit about the Sun using little or no fuel is a pretty neat trick by anyone’s standards.. The Chinese team’s calculations demonstrate the point. They show that a 10 kg sail in retrograde orbit, that hits Apophis a year before 2029, would deflect it enough to miss the keyhole, thereby eliminating the chance that the asteroid will return in 2036.
And such a mission ought to be relatively cheap and relatively easy to deploy.
That sounds easy enough. In practice, however, threading this camel through the eye of a needle will be extremely tricky. There are all kinds of variations in the solar wind that could send such a spacecraft wildly off course.
It also requires a huge sail that will be difficult to unfurl and also liable to damage during the course of the journey, which will itself take years.
Then there’s the structure and make up of Apophis, which is a complete mystery. Without knowing the material properties of the asteroid, it’s impossible to determine how the impact will affect it.
So there’s a little more work to be done in Beijing before this plan can get off the ground. Perhaps they should team up with the Europeans we talked about the other week.
Ref: arxiv.org/abs/1108.3183: Utilization of H-reversal Trajectory of Solar Sail for Asteroid Deflection
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:21415517-8b57-4062-8bd6-244554b55cde> | 3.296875 | 645 | Truncated | Science & Tech. | 55.727473 | 95,491,780 |
Java functions are among the best things for programmers to work with as Java sites can be very easy to read and prepare. Java especially simplifies many processes in the coding industry as it helps integrate many forms of technology and different display functions to keep the overall setup running more care and control.
However, there is always plenty of room for improvement when getting any kind of Java process running right. There are many things that can be done to make it easier for Java functions to be run the right way.
Don’t Create Unnecessary Objects
First, it is important to ensure that the objects being created through Java are absolutely functional to the success of a website. A website must be designed with an organization that is doesn’t include anything unnecessary. Unnecessary objects can make it harder for a website to operate and load up. Keeping and unnecessary items out will help keep the coding setup shorter and therefore easier to load.
Avoid Wrapper Classes
Wrapper classes can store information on everything within a site and may be too complicated. It can take a long time to load up some of these classes. A primitive class may be used instead as this focuses on values above all else.
Avoid Null Collections
Some arrays, collections and other features may end up being empty. You have to return them as being empty instead of being null. This is to keep the testing process from being hurt by a slow setup that is far too complicated and difficult to follow. If used right, it should make for a setup that is not too complicated and should be easy to follow.
A blank string can be returned if anything null is to appear. This is to keep the testing process simple without wasting more of an effort than necessary.
Keep Class Fields from Being Public
Class fields need to be private so no one can potentially change values of certain codes. Any changes can cause bugs and other serious errors to develop within a program. Private strings can be created to ensure data is controlled carefully and that the right details are aired to the public within the code.
A clone of an array may also be incorporated at this point instead of an actual array on its own. This is to keep the method or public data being easier to follow.
Avoid Abstract Ideas
Many interfaces can be created within Java to make data accessible and easier to read. The interfaces should be coded when the developer knows everything about how a program is to be generated. All abstract concepts must be avoided; these refer to points where the interface might be fluid or flexible.
While the idea of making a code less flexible doesn’t sound appealing to all, the need to avoid abstract ideas in the interface is critical. There may be times when a certain program cannot be easier accessed; these include times when a mobile device is unsuccessfully trying to get onto a website that it cannot easily read. An interface must be designed to where a certain format may be used depending on where access comes.
Keep Local Variable Limited
Local variables may be reviewed with care but you must keep them as small as possible when generating codes. Local variables that are too long or detailed can take a long time to load up and are often harder for a website to read. Avoid local variables that are too hard to follow and it should be easier for your site to stay active and quick-loading.
Java is a great programming language when used right. Be careful when you are getting it ready to work for your needs. You must keep your Java plans as fluid and easy to figure out as possible. This is to allow anything you are doing within your business as easy to follow as possible
Viewers will learn about arithmetic and Boolean expressions in Java and the logical operators used to create Boolean expressions. We will cover the symbols used for arithmetic expressions and define each logical operator and how to use them in Boole… | <urn:uuid:4d73e04a-4189-4581-b353-7966c133da0d> | 2.59375 | 772 | Tutorial | Software Dev. | 46.06705 | 95,491,800 |
This work describes the development of radiation detection systems to identify and image special nuclear material (SNM) using low energy gamma rays. The imaging of these materials is crucial for timely, in the field responses to potential threats to national security. Using a spectroscopy system, the sources can be identified while images can be produced concurrently for the sources which are present. Two systems were designed and characterized in this study, a collimated imager which used collimation in front of a small CdTe detector, and a pixelated pinhole imager, using a pinhole mask in front of a pixelated CZT detector. Low energy gamma rays are notoriously hard to detect and image, so differing collimation or masking schemes as well as varying imaging techniques were applied to each system. The systems were modeled using geometric and mathematical approximations, then simulated using Monte Carlo methods before finally being implemented in laboratory experiments. Varying the collimator or pinhole mask materials as well as the distance and type of radiation source, over energy ranges applicable to that of SNM, provided experimental setups that could mimic field interdiction work.
The results for both systems were images with a spatial resolution of better than 1 cm as well as energy spectra that could be used to identify the radiation source present. The collimated imager is able to detect material up to one meter distant while in a self- contained, portable enclosure. For the pinhole mask in front of the pixelated detector, using a single pinhole optimized for the pixelated detector geometry gave a high- resolution image, though poor geometric efficiency. Using the multiple pinhole mask rather than a single pinhole created several sub-images per detection run which can then be used to synthesize detailed reconstructions of the original source, with increased resolution over that of the individual sub-images. The single and multiple mask pinhole designs were compared. The multiple pinhole design had two benefits over the single pinhole, this design greatly increased the geometric efficiency and thus the total intensity on the detector, and the information contained in the full array of sub-images was also used to extract depth of field information about the radiation sources.
Radiation detection, spatial imaging, pixelated detector, multiple pinhole imaging
Level of Degree
First Committee Member (Chair)
Second Committee Member
Cassiano de Oliveira
Third Committee Member
Baldez, Phoenix. "Design and Characterization of Systems for Direct Spatial Imaging of Low-Energy Gamma-Radiation Sources." (2018). http://digitalrepository.unm.edu/ne_etds/68 | <urn:uuid:81baffe7-c55d-4e0c-900c-08649ce3c504> | 3.0625 | 531 | Academic Writing | Science & Tech. | 15.018797 | 95,491,813 |
Plants are unique organisms. They can produce sugars just from sunlight, carbon dioxide and water. This ability to directly synthesize their own food has enabled plants to successfully colonise, adapt to, and diversify within almost every niche on the planet and biologists estimate the total number of plant species to be about 250,000.
Plants are the primary producers of biomass providing animals and mankind with food, feed, paper, medicine, chemicals, energy, and an enjoyable landscape. Now the fascinating world of plants itself will be in the spotlight - launched under the umbrella of the European Plant Science Organisation, EPSO in Brussels http://www.epsoweb.orga, a special day for plants shall take place on May 18th 2012. This coordinated activity will plant virtual and constantly germinating seeds in the collective mind of the European and World Public recalling that plant science is of critical significance to the social, environmental and economic landscape now and in the future.
The "Fascination of Plants Day" has been already adopted by more than 25 countries worldwide and the number is growing. All information about this initiative can be accessed via http://www.plantday12.eu and is supported by a network of national coordinators who voluntarily promote and disseminate the activity within their countries.
Anyone who would like to contribute to the Fascination of Plants Day (FoPD) is welcome to join in. Just contact your National Coordinator by clicking on "countries" at http://www.plantday12.eu to discuss and get access to all the supporting materials for the Fascination of Plants Day. The media are also kindly invited to get involved. Scientists, farmers, politicians and industrialists will discuss with them and present the latest state-of-the-art breakthroughs in the plant science world and explore all of the new potential applications plant sciences can offer.
The Fascination of Plants Day covers all plant related topics including basic plant science, agriculture, horticulture & gardening, forestry, plant breeding, plant protection, food & nutrition, environmental conservation, climate change mitigation, smart bioproducts, biodiversity, sustainability, renewable resources, plant science education & art.Contacts:
Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine
13.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Conference on Laser Polishing – LaP: Fine Tuning for Surfaces
12.07.2018 | Fraunhofer-Institut für Lasertechnik ILT
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering | <urn:uuid:74d36e40-72a0-4d77-ac8c-102f44f0c29d> | 3.25 | 1,115 | Content Listing | Science & Tech. | 36.008421 | 95,491,819 |
The first part of this approach is concerned with the elaboration of a radical polymerization model of styrene, based on a kinetic diagram that includes chemical and thermal initiation, propagation, termination by recombination and chain transfer to the monomer. Furthermore, volume contraction during polymerization is considered, as well as the gel and glass effects. The mathematical formalism that describes the model in terms of moments is explored in detail. The model was then used to predict the changes in monomer conversion and molecular weight after intermediate addition of initiator and monomer. The results of this operation are dependent on the conditions of the reaction mass, quantity, and moment of substance addition. Therefore, the simulations were performed at different times with respect to the gel effect; before, during and after this phenomenon, and also with respect to different temperatures and initiators. Increasing the initiator concentration before the gel effect leads to an earlier appearance of the phenomenon and to a decrease in molecular weight. The ratio (M) over bar (w)/(M) over bar (n) reveals a polydispersity index smaller for the intermediate addition of initiator. No significant changes take place during or after the gel effect. If along with the initiator, unreacted monomer used to dissolve the initiator) enters the reactor, a small dip in conversion is observed. The general conclusion of this paper reveals the intermediate addition of initiator as a method to control polymer properties and to prevent the "dead-end" polymerization of styrene. (C) Central European Science Journals. All rights reserved.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:a88f8752-f0fd-42c2-98dc-c90dd158d991> | 2.78125 | 336 | Academic Writing | Science & Tech. | 19.148293 | 95,491,820 |
|Unique Underground Ecosystem Revealed by Hebrew University Researchers Uncovers Eight Previously Unknown Species|
Discovery of eight previously unknown, ancient animal species within “a new and unique underground ecosystem” in Israel was revealed today by Hebrew University of Jerusalem researchers.
In a press conference on the Mt. Scopus campus of the Hebrew University, the researchers said the discovery came about when a small opening was found , leading to a cave extending to a depth of 100 meters beneath the surface of a quarry in the vicinity of Ramle, between Jerusalem and Tel Aviv. The quarry is operated by cement manufacturer Nesher Industries.
The cave, which has been dubbed the Ayalon Cave, is “unique in the world,” said Prof. Amos Frumkin of the Hebrew University Department of Geography. This is due mainly to its isolation from the outside world, since the cave’s surface is situated under a layer of chalk that is impenetrable to water. The cave, with its branches, extends over some 2½ kilometers, making it Israel’s second largest limestone cave. It is to remain closed to the public to permit further scientific research.
The invertebrate animals found in the cave – four seawater and freshwater crustaceans and four terrestial species – are related to but different from other, similar life forms known to scientists. The species have been sent to biological experts in both Israel and abroad for further analysis and dating. It is estimated that these species are millions of years old. Also found in the cave were bacteria that serve as the basic food source in the ecosystem.
“The eight species found thus far are only the beginning” of what promises to be “a fantastic biodiversity,” said Dr. Hanan Dimentman of the Hebrew University Alexander Silberman Institute of Life Sciences, another of the researchers involved in the project. He said that he expects further exploration to reveal several other unique life forms.
The animals found there were all discovered live, except for a blind species of scorpion, although Dr. Dimentman is certain that live scorpions will be discovered in further explorations and also probably an animal or animals which feed on the scorpions.
The underground cave includes an underground lake, in which the crustaceans were found. The lake is part of the Yarkon-Taninim aquifer, one of Israel’s two aquifers, yet is different in temperature and chemical composition from the main waters of the aquifer. The lake’s temperature and salinity indicates that its source is deep underground.
Among the interesting features of the discoveries thus far in the cave is that two of the crustaceans are seawater species and two others are of a types found in fresh or brackish water. This can provide insights into events occurring millions of years ago regarding the history of ancient bodies of water in the region.
In addition to Prof. Frumkin, who heads the unit for cave research in the Department of Geography, and Dr. Dimentman, others involved in the project are Prof. Dov Por and Prof. Aharon Oren of the Institute of Life Sciences, graduate student Israel Naaman, and several others. The Israel Water Commission has assisted in the research, as has Nesher Industries.
Yoel Feldschue, director-general of Nesher Industries, said today that Nesher will preserve the ecological ecosystem which has been revealed in the center of its quarry in order to avoid any damage to the important findings there. He added in that regard that he is hopeful that the planning authorities will enable the company to operate in alternate areas in order to help preserve the scientific site. | <urn:uuid:9274a24f-194e-4a31-95a7-d12fa5f891fd> | 3.078125 | 759 | News Article | Science & Tech. | 34.62544 | 95,491,824 |
Try adding together the dates of all the days in one week. Now multiply the first date by 7 and add 21. Can you explain what happens?
This task follows on from Build it Up and takes the ideas into three dimensions!
Find the sum and difference between a pair of two-digit numbers. Now find the sum and difference between the sum and difference! What happens?
Put the numbers 1, 2, 3, 4, 5, 6 into the squares so that the numbers on each circle add up to the same amount. Can you find the rule for giving another set of six numbers?
Ben’s class were cutting up number tracks. First they cut them into twos and added up the numbers on each piece. What patterns could they see?
Got It game for an adult and child. How can you play so that you know you will always win?
This challenge focuses on finding the sum and difference of pairs of two-digit numbers.
Find the sum of all three-digit numbers each of whose digits is odd.
In a Magic Square all the rows, columns and diagonals add to the 'Magic Constant'. How would you change the magic constant of this square?
Watch this animation. What do you notice? What happens when you try more or fewer cubes in a bundle?
We can arrange dots in a similar way to the 5 on a dice and they usually sit quite well into a rectangular shape. How many altogether in this 3 by 5? What happens for other sizes?
Tom and Ben visited Numberland. Use the maps to work out the number of points each of their routes scores.
Sweets are given out to party-goers in a particular way. Investigate the total number of sweets received by people sitting in different positions.
In this problem we are looking at sets of parallel sticks that cross each other. What is the least number of crossings you can make? And the greatest?
What happens if you join every second point on this circle? How about every third point? Try with different steps and see if you can predict what will happen.
Only one side of a two-slice toaster is working. What is the quickest way to toast both sides of three slices of bread?
This challenge encourages you to explore dividing a three-digit number by a single-digit number.
Investigate the sum of the numbers on the top and bottom faces of a line of three dice. What do you notice?
How many ways can you find to do up all four buttons on my coat? How about if I had five buttons? Six ...?
Can you find all the ways to get 15 at the top of this triangle of numbers? Many opportunities to work in different ways.
An investigation that gives you the opportunity to make and justify predictions.
This challenge, written for the Young Mathematicians' Award, invites you to explore 'centred squares'.
What happens when you round these three-digit numbers to the nearest 100?
Use two dice to generate two numbers with one decimal place. What happens when you round these numbers to the nearest whole number?
What happens when you round these numbers to the nearest whole number?
Use your addition and subtraction skills, combined with some strategic thinking, to beat your partner at this game.
Can you explain the strategy for winning this game with any target?
Choose any 3 digits and make a 6 digit number by repeating the 3 digits in the same order (e.g. 594594). Explain why whatever digits you choose the number will always be divisible by 7, 11 and 13.
Can you make dice stairs using the rules stated? How do you know you have all the possible stairs?
Are these statements always true, sometimes true or never true?
Strike it Out game for an adult and child. Can you stop your partner from being able to go?
Can you see why 2 by 2 could be 5? Can you predict what 2 by 10 will be?
What can you say about these shapes? This problem challenges you to create shapes with different areas and perimeters.
Can you put the numbers 1-5 in the V shape so that both 'arms' have the same total?
List any 3 numbers. It is always possible to find a subset of adjacent numbers that add up to a multiple of 3. Can you explain why and prove it?
Place the numbers from 1 to 9 in the squares below so that the difference between joined squares is odd. How many different ways can you do this?
Find out what a "fault-free" rectangle is and try to make some of your own.
How many centimetres of rope will I need to make another mat just like the one I have here?
How many pairs of numbers can you find that add up to a multiple of 11? Do you notice anything interesting about your results?
A game for two people, or play online. Given a target number, say 23, and a range of numbers to choose from, say 1-4, players take it in turns to add to the running total to hit their target.
Polygonal numbers are those that are arranged in shapes as they enlarge. Explore the polygonal numbers drawn here.
Find some examples of pairs of numbers such that their sum is a factor of their product. eg. 4 + 12 = 16 and 4 × 12 = 48 and 16 is a factor of 48.
In how many different ways can you break up a stick of 7 interlocking cubes? Now try with a stick of 8 cubes and a stick of 6 cubes.
In this game for two players, the idea is to take it in turns to choose 1, 3, 5 or 7. The winner is the first to make the total 37.
A three digit number abc is always divisible by 7 when 2a+3b+c is divisible by 7. Why?
Find a route from the outside to the inside of this square, stepping on as many tiles as possible.
Are these statements relating to odd and even numbers always true, sometimes true or never true?
While we were sorting some papers we found 3 strange sheets which seemed to come from small books but there were page numbers at the foot of each page. Did the pages come from the same book?
How many different journeys could you make if you were going to visit four stations in this network? How about if there were five stations? Can you predict the number of journeys for seven stations?
Compare the numbers of particular tiles in one or all of these three designs, inspired by the floor tiles of a church in Cambridge. | <urn:uuid:cfa967f5-adf4-4104-90ec-57418f1d47dd> | 3.90625 | 1,361 | Content Listing | Science & Tech. | 74.916124 | 95,491,882 |
Despite hysterical headlines from the fake media claiming the weather is weirding out due to man-made climate change, recent studies show that it’s mostly superstition and that our modern climate in fact is well within the range of natural climate variability.
If one really wants to understand today’s weather and climate, it is essential to keep it in perspective with respect to what has happened over the past 1000 years or more. This is why a number of scientists are busy reconstructing past weather patterns at locations worldwide.
Central Asia climate likely dominated by natural cycles
First, a new study published in the journal Climate of the Past authored by a team of researchers led by Feng Chen of the Key Laboratory of Tree-ring Physical and Chemical Research of China Meteorological Administration found that drought records from western and eastern Central Asia capture the regional dry/wet periods and that analyses indicate the existence of centennial (100–150 years), decadal (50–60, 24.4 and 11.4 years) and interannual (8.0 and 2.0-3.5 years) cycles.
The authors suspect that they may be linked with climate forcings, such as solar activity and ENSO.
This would tell us that climate in Central Asia is greatly dependent on the natural factors of solar and oceanic cycles, and not CO2.
Western US droughts worse 1000 years ago
Another recent study just appeared in the Journal of Climate and was authored by a team of scientists led by Toby R. Ault, Department of Earth and Atmospheric Science, Cornell University. The findings indicate that the western United States was affected by several megadroughts during the last 1200 years, especially during the (MCA; 800 to 1300 CE).
The scientists found that such drought events are inevitable and occur purely as a consequence of internal climate variability. The researchers also concluded that the observed clustering of megadroughts of the Medieval Climate Anomaly were more likely to have been caused by either “external forcing or by internal climate variability”.
Canada: Scotian warm water “part of the natural variability “
The journal Continental Shelf Research published a study authored by scientists led by David Brickman of the Canadian Bedford Institute of Oceanography. The team examined the warm subsurface water temperatures in the Scotian Shelf region of Eastern Canada 2012, 2014, and 2015.
They found that the observed warming trend should be considered as “part of the natural variability of the coupled atmosphere-ocean system”.
AMS: natural variability dominates observed trends
Another a team of scientists led by Elisabeth Kendon of the Met Office Hadley Centre in the United Kingdom published a paper in the journal of the American meteorological Society which found natural variability appears to dominate current observed trends over the southern United Kingdom (including an increase in the intensity of heavy summer rainfall over the last 30 years).
The authors, citing Sarojini et al., 2016, confirmed that the “attribution of rainfall trends to human influence on local and regional scales is not yet possible”. More uncertainty over the human fingerprint on global climate.
Central Europe precipitation anomalies even greater long ago
Finally a paper published in the International Journal of Climatology and authored by Petr Dobrovolný of the Department of Geography, Masaryk University, Czech Republic, reconstructed precipitation in Central Europe (Czech Republic).
Source: Dobrovolný et al., 2018.
Their findings revealed two long periods of low precipitation variability, in the 13th–14th centuries and 1630s–1850s, and that precipitation anomalies of larger amplitude and longer duration occurred in the earlier part of the last millennium than those found in the instrumental period. The new reconstruction does not indicate any exceptional recent decline in MJJ precipitation.
In summary, the new studies from all around the world show that weather extremes were as bad or worse in the past than they are currently. Today’s modern climate is in fact well in phase with natural variability.
The papers mentioned above are all presented by Kenneth Richard here.
July 13, 2018 at 11:52AM | <urn:uuid:8132f55d-0691-411c-a322-4531608408fe> | 3.203125 | 853 | News (Org.) | Science & Tech. | 32.170107 | 95,491,911 |
Where Has Global Warming Gone?
SEATTLE – For the last quarter of the twentieth century, the average temperature at the surface of the earth edged inexorably upward. Then, to the surprise even of scientists, it stopped. The concentration of carbon dioxide in the earth’s atmosphere continued to rise; indeed, it is higher today than it has been for centuries. And yet, for the last 15 years, according to the conventional way of measuring global warming, the planet does not seem to have become any hotter.
What explains this unexpected turn of events, and what does it mean for future climate policy?
The pause in the rise of surface temperatures is real. It can be observed in surveys of the surface of the sea and in satellite measurements of the troposphere. But the reason it has occurred is not that our greenhouse-gas emissions are no longer changing the earth’s climate; it is that surface temperature is a poor metric for human-induced warming. Indeed, what scientists have figured out is that, instead of warming the surface, the excess heat that is being generated has gone to the deeper oceans.
This calls into question some of the international strategies for combating climate change that are currently being negotiated, such as those aimed at preventing the global temperature at the earth’s surface from rising more than 2º Celsius above the pre-industrial average.
Scientists probably did not adequately convey to the public that their projections for future warming are based on models that account only for the so-called “forced response” in global mean surface temperatures – that is, the change caused by greenhouse-gas emissions. But what is observed at the surface includes unforced, or natural, variations, such as the El Niño and La Niña fluctuations from year to year, and the 60-70 year cycle from the fluctuations of the Great Ocean Conveyor Belt in the Atlantic.
Given the oceans’ massive heat-storage capacity, determining how much of the warming remains at the surface over the course of decades is a very difficult task. Though the challenge is beginning to be appreciated, current projections of the dreaded two-degree warming have yet to take into account variable ocean cycles.
To be sure, surface temperatures remain important. They are a better measure of the threats posed by climate change than heat sequestered underwater. But some of the threats that scientists (and economists) deduce from the surface temperature also reflect natural climate change, and thus cannot be mitigated through the reduction of CO2 emissions.
The total amount of heat contained in oceans responds to changes in emissions, and is therefore a better metric for measuring such responses. Indeed, it has continued to warm as expected, even as the surface temperature has stopped rising.
The oceans’ heat content is measured by a network of more than 3,000 free-drifting robotic floats spread out across the world’s waters, where they routinely dive 2,000 meters beneath the surface. The temperature they measure is transmitted to orbiting satellites and made available online to anyone in near-real time. For ease of interpretation, the oceans’ heat content can easily be converted to a mean temperature after dividing by a constant. In time, models could demonstrate how to relate this new global metric to emissions’ regional climate impact.
The intensive scientific search for an explanation for the pause in global warming at the earth’s surface has led to a better understanding of the complex functioning of the climate. It confirms the long-held theory that the earth has an energy budget that is affected by radiative perturbations at the top of the atmosphere, though partitioning that energy between the surface and the deeper oceans has been difficult.
Nobody knows how long the current pause will last. Nonetheless, at some point, the natural cycles will shift; the oceans will cease to absorb the bulk of the planet’s warming; and surface temperatures will begin to climb again. When they do, we can expect the increase to resume the rapid pace observed during the late twentieth century, when surface temperature rose by about 0.17 degrees Celsius every ten years.
In the meantime, whether the overall risk to our environment has been reduced by the pause remains an open question. Some argue that what went down will eventually come back up. The sloshing back and forth of warm and cold waters – El Niño and La Niña – in the shallow layer of the equatorial Pacific Ocean will continue to produce fluctuations in surface temperatures every year. Over longer periods, however, the risk that the heat currently stored in the deep ocean will resurface is remote.
One thing is clear. Monitoring surface temperatures does not give us an accurate enough representation of human-induced global warming. As long as we lack a clear understanding of the relationship between our cumulative greenhouse-gas emissions and the temperature of the earth, it will remain difficult to assess the potential for damage related to climate change caused by humans – or develop the right strategies to minimize it.
Copyright: Project Syndicate, 2014.
This article is brought to you by Project Syndicate that is a not for profit organization.
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Apr 24, 2017 10:12 AM EDT
Scientists from Caltech have discovered a new state of matter which they say will help advance quantum computing and the microchip technology. The new state of matter is 3D quantum liquid crystals.
Quantum liquid crystals are unique because they flow freely like liquid but they are directionally oriented like solids. More so, the magnetic properties of its electrons vary depending on their flow direction along a given axis. That means, these materials can become magnets when electricity is applied to them or the strength of their magnets can also have different levels.
These liquid crystals can be produced artificially with some of its practical applications as display screens of most electronic devices. In nature, they can be found in biological cell membranes.
With the discovery of 3D quantum liquid crystals, the scientists are hoping that more efficient and powerful computer chips can be created to help them exploit the direction of the electrons. Furthermore, these crystals might lead to developing a more viable quantum computer because of the nature of these particles. With quantum computers, scientists will be able to decrypt codes and make calculations much faster than now.
At present, scientists are finding a more efficient method to hurdle the challenges of building a quantum computer. One major challenge is to be able to 'tame' these quantum effects because they are easily broken and transient.
David Hsieh, assistant professor at Caltech and the main author of the study, said that 3D quantum liquid crystals could be the "precursor to the topological superconductors" that scientists have been trying to figure out.
He added that instead of relying on luck and chance in trying to discover superconductors, 3D quantum crystals could actually be the way that will lead to them.
The study was published in the journal Science.
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When you have 400 earthquakes on top of one of the largest supervolcanoes on Earth, people pay attention.
And since the day after Christmas, that's what has happened at Yellowstone National Park. Scientists are seeing what they call a "swarm" of low-intensity earthquakes - the largest since the 1980s. The biggest quake had a magnitude of 3.9, below the level that can cause damage.
But the earthquakes have made worldwide news because the park lies on a giant caldera, the crater of a volcano that scientists say could one day explode and destroy most of North America and freeze the rest of the world under a shroud of ash for up to two years.
Still, the latest earthquakes are nothing to fear, said park geologist Hank Heasler.
Heasler and his colleagues at the University of Utah and the U.S. Geological Survey spent several hours Friday on a conference call comparing notes and sharing their views on the latest geological event atop the largest known volcano in the world.
Yellowstone has several thousand tiny earthquakes a year but this recent swarm is unusual - and geologically speaking, maybe even timely.
The last time Yellowstone erupted 640,000 years ago it spewed 8,000 times the ash and lava that came from Mount St. Helens in 1980. The past two explosive eruptions have come at 600,000-year intervals, so some geologists say the next one is overdue. But there have been 30 relatively minor eruptions since then.
"Looking at the data, currently we don't see any indication of volcanic activity," Heasler said.
Most of the recent earthquakes have centered around Yellowstone Lake, an especially hot and active geothermal region. Five miles below the lake lies a giant magma chamber, which scientists say has bulged upward about 60 feet over the past 50 years.
But the latest earthquakes have not changed things noticeably, Heasler said.
"Scientists don't currently see any indication of uplift," Heasler said. "We're not seeing a bulge at this time." Based on the observations of Heasler and his colleagues, authorities have kept Yellowstone's volcanic alert level at green, which means they aren't worried yet. The earthquakes hadn't stopped as of Monday.
Yellowstone's volcano sits atop a "hot spot" of molten rock that rises from deep within the Earth. For more than 17 million years, the North American Plate has moved west-southwest over this largely stationary spot, causing volcanic eruptions, including those that formed the Eastern Snake River Plain in Idaho.
Scientists aren't sure what the connection is between earthquake clusters like this and the volcanic activity responsible for Yellowstone's signature features, such as Old Faithful, Mammoth Hot Springs and many of the mud pots and geysers that most visitors associate with the park.
And though the chances of a major eruption at Yellowstone make the headlines, scientists expect the next volcanic eruptions in the park to be non-explosive lava flows. Though these would still be destructive, they likely would be limited to the park and perhaps surrounding areas.
The last earthquake swarm in Yellowstone came in 1985. It lasted several months and the biggest earthquake was magnitude 4.5, Heasler said. So Yellowstone may be due for some modest action before this one is over.
© 2009, The Idaho Statesman (Boise, Idaho).
Visit The Idaho Statesman online at www.idahostatesman.com
Distributed by McClatchy-Tribune Information Services.
Explore further: Earthquakes and eruptions | <urn:uuid:1947f42b-78e0-429e-a46a-7b834b7a9889> | 3.484375 | 732 | News Article | Science & Tech. | 49.377977 | 95,491,961 |
The part of the nebula visible in this image from Hubble's Advanced Camera for Surveys is criss-crossed with tendrils of dust and gas churned up by recent supernovae. These supernova remnants include NGC 2060, visible above and to the left of the centre of this image, which contains the brightest known pulsar.
Hubble has taken this stunning close-up shot of part of the Tarantula Nebula. This star-forming region of ionised hydrogen gas is in the Large Magellanic Cloud, a small galaxy which neighbors the Milky Way. It is home to many extreme conditions including supernova remnants and the heaviest star ever found. The Tarantula Nebula is the most luminous nebula of its type in the local universe. Credit: NASA, ESA
The tarantula's bite goes beyond NGC 2060. Near the edge of the nebula, outside the frame, below and to the right, lie the remains of supernova SN 1987a, the closest supernova to Earth to be observed since the invention of telescopes in the 17th century.
Hubble and other telescopes have been returning to spy on this stellar explosion regularly since it blew up in 1987, and each subsequent visit shows an expanding shockwave lighting up the gas around the star, creating a pearl necklace of glowing pockets of gas around the remains of the star. SN 1987a is visible in wide field images of the nebula, such as that taken by the MPG/ESO 2.2-metre telescope.
Together with dying stars, the Tarantula Nebula is packed with young stars which have recently formed from the nebula's supply of hydrogen gas. These toddler-stars shine forth with intense ultraviolet light that ionises the gas, making it light up red.
The light is so intense that although around 170 000 light-years distant, and outside the Milky Way, the Tarantula Nebula is nevertheless visible without a telescope on a dark night to Earth-bound observers. This nebula might be far away, but it is the most luminous example of its type that astronomers have observed in the local Universe.
A compact and extremely bright star cluster called RMC 136 (http://www.spacetelescope.org/images/opo0932a/) lies above and to the left of this field of view, providing much of the radiation that powers the multi-coloured glow. Until recently, astronomers debated whether the source of the intense light was a tightly bound cluster of stars, or perhaps an unknown type of super-star thousands of times bigger than the Sun. It is only in the last 20 years, with the fine detail revealed by Hubble and the latest generation of ground-based telescopes, that astronomers have been able to conclusively prove that it is, indeed, a star cluster.
But even if the Tarantula Nebula doesn't contain this hypothetical super-star, it still hosts some extreme phenomena, making it a popular target for telescopes. Within the bright star cluster lies star RMC 136a1, which was recently found to be the heaviest ever discovered, at around 300 times the mass of the Sun at its birth (http://www.eso.org/public/news/eso1030/). This heavyweight is challenging astronomers' theories of star formation, smashing through the upper limit they thought existed on star mass.
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
Image credit: NASA, ESA
- Images of Hubble: http://www.spacetelescope.org/images/archive/category/spacecraft/
- http://www.naic.edu/~gibson/30dor/- http://coolcosmos.ipac.caltech.edu/cosmic_classroom/multiwavelength_
Oli Usher | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine | <urn:uuid:2fb3ac1a-f2d2-41d4-96d5-05d946779f3c> | 3.53125 | 1,423 | Content Listing | Science & Tech. | 46.241854 | 95,491,965 |
Top: Artist's rendering of the MarCO CubeSats
Bottom: Artist's rendering of the InSight lander
Interior Exploration using Seismic Investigations, Geodesy and Heat Transport |
Geophysical Monitoring Station
|Mission type||Mars lander|
|Operator||NASA / JPL|
Planned: 2 years on Mars |
Elapsed: 2 months, 11 days
|Manufacturer||Lockheed Martin Space Systems|
|Launch mass||694 kg (1,530 lb)|
|Landing mass||358 kg (789 lb)|
|Dimensions||Deployed: 6.0 × 1.56 × 1.0 m (19.7 × 5.1 × 3.3 ft)|
|Power||600 W, solar / Li-ion battery|
|Start of mission|
|Launch date||5 May 2018, 11:05UTC|
|Rocket||Atlas V 401|
|Launch site||Vandenberg SLC-3E|
|Contractor||United Launch Alliance|
|Landing date||26 November 2018 (planned)|
Elysium Planitia |
|Flyby of Mars|
|Closest approach||26 November 2018 (planned)|
InSight is a robotic lander designed to study the interior of the planet Mars. The mission launched on 5 May 2018 at 11:05 UTC and is expected to land on the surface of Mars at Elysium Planitia on 26 November 2018, where it will deploy a seismometer and burrow a heat probe. It will also perform a radio science experiment to study the internal structure of Mars.
The lander was manufactured by Lockheed Martin Space Systems and was originally planned for launch in March 2016. Due to the failure of its SEIS instrument prior to launch, NASA announced in December 2015 that the mission had been postponed, and in March 2016, the launch was rescheduled for 5 May 2018, when it launched successfully. The name is a backronym for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport.
InSight's objective is to place a stationary lander equipped with a seismometer and heat transfer probe on the surface of Mars to study the planet's early geological evolution. This could bring new understanding of the Solar System's terrestrial planets — Mercury, Venus, Earth, Mars — and the Earth's Moon. By reusing technology from the Mars Phoenix lander, which successfully landed on Mars in 2008, it is expected that the cost and risk will be reduced.
Following a persistent vacuum failure in the main scientific instrument, the launch window was missed, and the InSight spacecraft was returned to Lockheed Martin's facility in Denver, Colorado, for storage. NASA officials decided in March 2016 to spend an estimated US$150 million to delay launching InSight to May 2018. This would allow time for the seismometer issue to be fixed, although it increased the cost from the previous US$675 million to a total of $830 million.
History and background
InSight was initially known as GEMS (Geophysical Monitoring Station), but its name was changed in early 2012 following a request by NASA. Out of 28 proposals from 2010, it was one of the three Discovery Program finalists receiving US$3 million in May 2011 to develop a detailed concept study. In August 2012, InSight was selected for development and launch. Managed by NASA's Jet Propulsion Laboratory (JPL) with participation from scientists from several countries, the mission is cost-capped at US$425 million, not including launch vehicle funding.
A persistent vacuum leak in the CNES-supplied seismometer known as the Seismic Experiment for Interior Structure (SEIS) led NASA to postpone the planned launch in March 2016 to May 2018. NASA's Jet Propulsion Laboratory took over development of the vacuum container for SEIS, with CNES handling instrument integration and test activities. The difficulty of an interplanetary seismometer was experienced by NASA when the Viking 1 lander's seismometer did not deploy properly in 1976. The seismometers on Viking were mounted on the lander, which meant that it also picked up vibrations from various operations of the lander and by the wind. The seismometer readings were used to estimate a Martian geological crust thickness between 14 and 18 km (8.7 and 11.2 mi) at the Viking 2 lander site. The Viking 2 seismometer detected pressure from the Mars winds complementing the meteorology results. There was one candidate for a possible Marsquake, although it was not confirmed due to the limitations of the design, especially due to noise from other sources like wind. The wind data did prove useful in its own right, and despite the limitations of the data, widespread and large seismic events could be ruled out (large Marsquakes were not detected).
Seismometers were also left on the Moon by the Apollo 12, 14, 15 and 16 missions and provided many insights into lunar seismology, including the discovery of moonquakes. The Apollo seismic network, which was operated until 1977, detected at least 28 moonquakes up to 5.5 on the richter scale.
Radio Doppler measurements were taken with Viking and twenty years later with Mars Pathfinder, and in each case the axis of rotation of Mars was calculated. By combining this data the core size was constrained, because the change in axis of rotation over 20 years allowed a precession rate and from that the planet's moment of inertia to be calculated.
When InSight was delayed, the rest of the spacecraft was returned to Lockheed Martin's factory in Colorado for storage, and the Atlas V rocket intended to launch the spacecraft was reassigned to the WorldView-4 mission.
NASA officials announced on 9 March 2016 that InSight would be delayed until the 2018 launch window at an estimated cost of US$150 million. The spacecraft was rescheduled to launch on 5 May 2018 for a Mars landing on 26 November; the flight plan remained unchanged with launch using an Atlas V rocket from Vandenberg Air Force Base in California. NASA's Jet Propulsion Laboratory was tasked with redesigning and building a new vacuum enclosure for the SEIS instrument, while CNES conducted instrument integration and testing.
On 22 November 2017 InSight completed testing in a thermal vacuum, also known as TVAC testing, where the spacecraft is put in simulated space conditions with reduced pressure and various thermal loads. On 23 January 2018 its solar panels were deployed and tested, and a second silicon chip containing 1.6 million names from the public was added to the lander.
InSight will place a single stationary lander on Mars to study its deep interior and address a fundamental issue of planetary and Solar System science: understanding the processes that shaped the rocky planets of the inner Solar System (including Earth) more than four billion years ago.
InSight's primary objective is to study the earliest evolutionary history of the processes that shaped Mars. By studying the size, thickness, density and overall structure of Mars' core, mantle and crust, as well as the rate at which heat escapes from the planet's interior, InSight will provide a glimpse into the evolutionary processes of all of the rocky planets in the inner Solar System. The rocky inner planets share a common ancestry that begins with a process called accretion. As the body increases in size, its interior heats up and evolves to become a terrestrial planet, containing a core, mantle and crust. Despite this common ancestry, each of the terrestrial planets is later shaped and molded through a poorly understood process called differentiation. InSight mission's goal is to improve the understanding of this process and, by extension, terrestrial evolution, by measuring the planetary building blocks shaped by this differentiation: a terrestrial planet's core, mantle and crust.
The mission will determine if there is any seismic activity, measure the amount of heat flow from the interior, estimate the size of Mars' core and whether the core is liquid or solid. This data would be the first of its kind for Mars. It is also expected that frequent meteor airbursts (10–200 detectable events per year for InSight) will provide additional seismo-acoustic signals to probe the interior of Mars. The mission's secondary objective is to conduct an in-depth study of geophysics, tectonic activity and the effect of meteorite impacts on Mars, which could provide knowledge about such processes on Earth. Measurements of crust thickness, mantle viscosity, core radius and density, and seismic activity should result in an accuracy increase of 3× to 10× compared with current data.
In terms of fundamental processes shaping planetary formation, it is thought that Mars contains the most in-depth and accurate historical record, because it is big enough to have undergone the earliest accretion and internal heating processes that shaped the terrestrial planets, but is small enough to have retained signs of those processes.
The mission further develops a design inherited from the 2008 Phoenix Mars Lander. Because InSight is powered by solar panels, it will land near the equator to enable maximum power for a projected lifetime of 2 years (1 Martian year). InSight is designed to be launched by an Atlas V rocket; the mission will include two CubeSats that will launch with InSight but will fly separately to Mars.
- Total: 694 kg (1,530 lb)
- Mars Cube One CubeSats: 13.5 kg (30 lb) each
- About 6.0 m (19.7 ft) wide with solar panels deployed. The science deck is about 1.56 m (5.1 ft) wide and between 0.83 and 1.08 m (2.7 and 3.5 ft) high (depending on leg compression after landing). The length of the robotic arm is 2.4 m (7.9 ft)
- Power is generated by two round solar panels, each 2.15 m (7.1 ft) in diameter and consisting of SolAero ZTJ triple-junction solar cells made of InGaP/InGaAs/Ge arranged on Orbital ATK UltraFlex arrays. After touchdown on the Martian surface, the arrays are deployed by opening like a folding fan.
InSight's payload has a total mass of 50 kg, including science instruments and support systems such as the Auxiliary Payload Sensor Suite, cameras, the instrument deployment system, and a laser retroreflector. The science payload consists of two main instruments, SEIS and HP3:
- The Seismic Experiment for Interior Structure (SEIS) will take precise measurements of quakes and other internal activity on Mars to better understand the planet's history and structure. It will also investigate how the Martian crust and mantle respond to the effects of meteorite impacts, which gives clues to the planet's inner structure. SEIS was provided by the French Space Agency (CNES), with the participation of the Institut de Physique du Globe de Paris (IPGP), the Swiss Federal Institute of Technology (ETH), the Max Planck Institute for Solar System Research (MPS), Imperial College, Institut supérieur de l'aéronautique et de l'espace (ISAE) and JPL. The seismometer will also detect sources including atmospheric waves and gravimetric signals (tidal forces) from Mars' moon Phobos, up to high frequency seismic waves of 50 Hz. SEIS was found to have a vacuum leak which could not be corrected in time for the launch of InSight, forcing a two-year mission postponement.
- The SEIS instrument is supported by a suite of meteorological tools to characterize atmospheric disturbances that might affect the experiment. These include a vector magnetometer provided by UCLA that will measure magnetic disturbances such as those caused by the Martian ionosphere; a suite of air temperature, wind speed and wind direction sensors based on the Spanish/Finnish Rover Environmental Monitoring Station; and a barometer from JPL.
- The Heat Flow and Physical Properties Package (HP3), provided by the German Aerospace Center (DLR), is a self-penetrating heat flow probe. Referred to as a "self-hammering nail" and nicknamed "the mole", it was designed to burrow as deep as 5 m (16 ft) below the Martian surface while trailing a tether with embedded heat sensors to measure how efficiently heat flows through Mars' core, and thus reveal unique information about the planet's interior and how it has evolved over time. It trails a tether containing precise temperature sensors every 10 cm (3.9 in) to measure the temperature profile of the subsurface. The tractor mole of the instrument was provided by the Polish company Astronika.
- The Rotation and Interior Structure Experiment (RISE) led by the Jet Propulsion Laboratory (JPL), will use the lander's X-band radio to provide precise measurements of planetary rotation to better understand the interior of Mars. X-band radio tracking, capable of an accuracy under 2 cm, will build on previous Viking program and Mars Pathfinder data. The previous data allowed the core size to be estimated, but with more data from InSight, the nutation amplitude can be determined. Once spin axis direction, precession, and nutation amplitudes are better understood, it should be possible to calculate the size and density of the Martian core and mantle. This should increase our understanding of the formation of terrestrial planets (e.g. Earth) and rocky exoplanets.
- Temperature and Winds for InSight (TWINS), fabricated by Spain's Centro de Astrobiología, will monitor weather at the landing site.
- Laser RetroReflector for InSight (LaRRI) is a corner cube retroreflector provided by the Italian Space Agency and mounted on InSight's top deck. It will enable passive laser range-finding by orbiters even after the lander is retired, and would function as a node in a proposed Mars geophysical network. This device previously flew on the Schiaparelli lander as the Instrument for Landing-Roving Laser Retroreflector Investigations (INRRI), and was an aluminum dome 54 mm (2.1 in) in diameter and 25 g (0.9 oz) in mass featuring eight fused silica reflectors.
- Instrument Deployment Arm (IDA) is a 2.4 m robotic arm that will be used to deploy the SEIS and HP3 instruments to Mars' surface.
- The Instrument Deployment Camera (IDC) is a color camera based on the Mars Exploration Rover and Mars Science Laboratory navcam design. It is stationed on the Instrument Deployment Arm and will image the instruments on the lander's deck and provide stereoscopic views of the terrain surrounding the landing site. It features a 45-degree field of view and uses a 1024 × 1024 pixel CCD detector. The IDC sensor was originally black and white; a program was enacted that tested with a standard hazcam and, since development deadlines and budgets were met, was replaced with a color sensor.
- The Instrument Context Camera (ICC) is a color camera based on the MER/MSL hazcam design. It is mounted below the lander's deck, and with its wide-angle 120-degree panoramic field of view will provide a complementary view of the instrument deployment area. Like the IDC, it uses a 1024 × 1024 pixel CCD detector.
|Wikinews has related news: NASA's InSight lander and MarCO craft launch in new mission to Mars|
The spacecraft was launched on 5 May 2018 at 11:05 UTC on an Atlas V 401 launch vehicle (AV-078) from Vandenberg Air Force Base Space Launch Complex 3-East. This was the first American interplanetary mission to launch from California.
The launch was managed by NASA's Launch Services Program. InSight was originally scheduled for launch on 4 March 2016 on an Atlas V 401 (4 meter fairing/zero (0) solid rocket boosters/single (1) engine Centaur) from Vandenberg Air Force Base in California, U.S., but was called off in December 2015 due to a vacuum leak on the SEIS instrument. The rescheduled launch window ran from 5 May to 8 June 2018.
The journey to Mars will take 6.5 months across 484 million km (301 million mi) for a touchdown expected on 26 November. If it lands successfully, a two-month-long deployment phase would commence as part of its two-year (about one Martian year) prime mission.
Planned landing site
As InSight's science goals are not related to any particular surface feature of Mars, potential landing sites were chosen on the basis of practicality. Candidate sites needed to be near the equator of Mars to provide sufficient sunlight for the solar panels year round, have a low elevation to allow for sufficient atmospheric braking during EDL, flat, relatively rock-free to reduce the probability of complications during landing, and soft enough terrain to allow the heat flow probe to penetrate well into the ground. An optimal area that meets all these requirements is Elysium Planitia, so all 22 initial potential landing sites were located in this area. The only two other areas on the equator and at low elevation, Isidis Planitia and Valles Marineris, are too rocky. In addition, Valles Marineris has too steep a gradient to allow safe landing.
In September 2013, the initial 22 potential landing sites were narrowed down to 4, and the Mars Reconnaissance Orbiter was then used to gain more information on each of the 4 potential sites before a final decision was made. Each site consists of a landing ellipse that measures about 130 by 27 km (81 by 17 mi). In March 2017, scientists from the Jet Propulsion Laboratory announced that the landing site had been selected. It is located in western Elysium Planitia at . The landing site is about 600 km (370 mi) from where the Curiosity rover is operating in Gale Crater.
Team and participation
The InSight science and engineering team includes scientists and engineers from many disciplines, countries and organizations. The science team assigned to InSight includes scientists from institutions in the U.S., France, Germany, Austria, Belgium, Canada, Japan, Switzerland, Spain and the United Kingdom.
Mars Exploration Rover project scientist W. Bruce Banerdt is the principal investigator for the InSight mission and the lead scientist for the SEIS instrument. Suzanne Smrekar, whose research focuses on the thermal evolution of planets and who has done extensive testing and development on instruments designed to measure the thermal properties and heat flow on other planets, is the lead for InSight's HP3 instrument. Sami Asmar, an expert in advanced studies using radio waves, is the lead for InSight's RISE investigation. The InSight mission team also includes project manager Tom Hoffman and deputy project manager Henry Stone.
Major contributing agencies and institutions:
- National Aeronautics and Space Administration (NASA)
- Centre National d'Études Spatiales (CNES)
- Deutsches Zentrum für Luft- und Raumfahrt (DLR)
- Jet Propulsion Laboratory (NASA/JPL)
- Lockheed Martin
- Institut de Physique du Globe de Paris (IPGP)
- Swiss Federal Institute of Technology in Zurich (ETHZ)
- Max Planck Institute for Solar System Research (MPS)
- Imperial College London
- Institut supérieur de l'aéronautique et de l'espace (ISAE-SUPAERO)
- University of Oxford
- Centro de Astrobiología (CAB)
- Centrum Badan Kosmicznych (CBK)
As part of its public outreach, NASA organized a program where members of the public were able to have their names sent to Mars aboard InSight. Due to its launch delay, two rounds of sign-ups were conducted totaling 2.4 million names: 826,923 names were registered in 2015 and a further 1.6 million names were added in 2017. An electron beam was used to etch letters only 1⁄1000 the width of a human hair onto 8 mm (0.3 in) silicon wafers. The first chip was installed on the lander in November 2015 and the second on 23 January 2018.
The Mars Cube One (MarCO) spacecraft are a pair of 6U CubeSats that piggybacked with the InSight mission to test CubeSat navigation and endurance in deep space, and to help relay real-time communications during the probe's entry, descent and landing (EDL) phase. The two 6U CubeSats, named "MarCO" A and B, are identical. They measure 30 cm × 20 cm × 10 cm (11.8 in × 7.9 in × 3.9 in) and are flying as a pair for redundancy. They will not enter orbit but fly past Mars during the EDL phase of the mission and relay InSight's telemetry in real time. MarCO is a technology capability demonstration of a communications relay system.
The Atlas V Booster launched the MarCO CubeSats together with the InSight cruise stage; afterwards, the two CubeSats separated from the cruise stage after launch and are flying their own trajectory to Mars. This is notably different from the twin Deep Space 2 probes, which were attached to the Mars Polar Lander cruise stage on its way to Mars. Near Mars, the Deep Space 2 probes separated for their mini-mission, but they were never heard from, and Mars Polar Lander was lost on landing (Mars Global Surveyor was in orbit for communication at that time).
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But scientists theorize that this solar geoengineering could have a side effect of whitening the sky during the day. New research indicates that blocking 2 percent of the sun's light would make the sky three- to-five times brighter, as well as whiter.
Carbon dioxide emissions from the burning of coal, oil, and gas have been increasing over the past decades, causing the Earth to get warmer. Large volcanic eruptions cool the planet by creating lots of small particles in the stratosphere, but the particles fall out within a couple of years, and the planet heats back up. The idea behind solar geoengineering is to constantly replenish a layer of small particles in the stratosphere, mimicking this volcanic aftermath and scattering sunlight back to space.
Using advanced models, Carnegie's Ben Kravitz and Ken Caldeira, along with Douglas MacMartin from the California Institute of Technology, examined changes to sky color and brightness from using sulfate-based aerosols in this way. They found that, depending on the size of the particles, the sky would whiten during the day and sunsets would have afterglows. Their work will be published 1 June in Geophysical Research Letters, a journal of the American Geophysical Union.
The scientists' models predict that the sky would still be blue, but it would be a lighter shade than what most people are used to looking at now. The research team's work shows that skies everywhere could look like those over urban areas in a world with this type of geoengineering taking place. In urban areas, the sky often looks hazy and white.
"These results give people one more thing to consider before deciding whether we really want to go down this road," Kravitz said. "Although our study did not address the potential psychological impact of these changes to the sky, they are important to consider as well."
There are several larger environmental implications to the group's findings, too. Because plants grow more efficiently under diffuse light conditions such as this, global photosynthetic activity could increase, pulling more of the greenhouse gas carbon dioxide out of the atmosphere. On the other hand, the effectiveness of solar power could be diminished, as less sunlight would reach solar-power generators.
"I hope that we never get to the point where people feel the need to spray aerosols in the sky to offset rampant global warming," Caldeira said. "This is one study where I am not eager to have our predictions proven right by a global stratospheric aerosol layer in the real world."
Title: "Geoengineering: Whiter Skies?"
Authors: Ben Kravitz: Department of Global Ecology, Carnegie Institution for Science, Stanford, California, USA; Douglas G MacMartin: Department of Control and Dynamical Systems, California Institute of Technology, Pasadena, California, USA; Ken Caldeira: Department of Global Ecology, Carnegie Institution for Science, Stanford, California, USA.
Contact Information for the Authors: Ben Kravitz, Email: email@example.com
Kate Ramsayer | American Geophysical Union
Global study of world's beaches shows threat to protected areas
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NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
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19.07.2018 | Materials Sciences | <urn:uuid:7ad3a346-32da-4d88-86e9-6364397118eb> | 3.8125 | 1,260 | Content Listing | Science & Tech. | 40.35363 | 95,491,987 |
A teacher gave a test to a class in which of the students are juniors and are seniors. The average score on the test was . The juniors all received the same score, and the average score of the seniors was . What score did each of the juniors receive on the test?
This problem is copyrighted by the American Mathematics Competitions.
Instructions for entering answers:
For questions or comments, please email email@example.com. | <urn:uuid:6f199d1d-1bf4-488c-a836-6ea698cf96f3> | 3.03125 | 96 | Tutorial | Science & Tech. | 53.704795 | 95,492,031 |
Breakthrough in search for ET as scientists develop method to see 'chemical fingerprints' from INSIDE other solar systems
- New technique can penetrate the dazzling light of distant stars
- Instruments were previously blinded by light while trying to see planets
- Scientists able to discern the 'chemical fingerprints' of the atmospheres of five planets 128 light years away
Astronomers today claimed to be a step closer to discovering alien life thanks to a new technique which allows them to make a remote reconnaissance of distant planets.
A project by researchers at Cambridge University has harnessed new software and instruments to collect the first chemical fingerprints of planets orbiting a star 128 light years away from Earth.
Previous techniques had only managed partial measurements of the system’s outermost planet before light from the star itself blinded the instruments.
Dazzling: After applying several advanced optical techniques the P1640 camera sees only a very small fraction of the light from HR8799 in this 'speckle' pattern. The images of the four planets are still hidden
While the planets proved 'too toxic and hot' for life as we know, study co-author Ian Parry said the techniques could one day give us the 'first secure evidence of life on a planet outside our solar system'.
The central star that the planets orbit, known as HR 8799, is five times brighter and produces about 1,000 times more ultraviolet light than the Sun.
In the past it has meant that the blinding starlight - tens of millions to billions of times brighter than the reflected light of the planets - has restricted how far astronomers can see.
Now, for the first time, scientists have been able to penetrate the starlight to read the unique light signatures of the chemical elements that make up the atmospheres of the four planets.
Project 1640, a collaboration between Cambridge academics and researchers from several U.S. institutions, used the Hale telescope at the Palomar Observatory in California.
Previously light from bright distant stars had so dazzled telescopes that it had been imposssible to clearly see planets orbiting them.
But, the scientists say, the new capabilities developed for Project 1640 allow for the rapid characterisation of exoplanets, giving information about their atmospheres and surface temperatures.
After using advanced software techniques the
speckle pattern can be removed and the images of the 4 planets are
revealed (labelled b-e). P1640 takes 30 pictures like this simultaneously with each one at a different wavelength (i.e. colour) so that a spectrum is measured for each planet
Ben Oppenheimer, of the American Museum of Natural History, said the new ability to go beyond starlight to read exoplanet atmospheres was like 'taking a single picture of the Empire State Building from an airplane that reveals the height of the building but also a bump on the sidewalk next to it that’s as high as a couple of bacteria'.
ASTRONOMERS COULD USE LIGHT FROM STARS TO MAP EXOPLANETS
Astronomers are developing a system to use reflected starlight to create maps of alien planets that show oceans, land and even clouds.
Developed by planetary scientist Nicolas Cowan and presented at a meeting of the American Astronomical Society in January, it is inspired by a technique previously used by military spy satellites.
The software can take a point of reflected starlight from an exoplanet, and analyse it to extract the unique signals required to form a rough map.
Because there is currently no telescope powerful enough to directly photograph a faraway rocky planet, Dr Cowan tested the software on images of Earth taken from a distant vantage point in space by Nasa's Deep Impact spacecraft as part of the EPOXI mission.
'The object of this experiment was to see whether we could identify the colours of surfaces on Earth, [and tell] how many major surfaces are there, and what they look like,' said Dr Cowan, who works at Northwestern University in Evanston, Illinois.
Project 1640 does this by sharpening and darkening a star’s light. This technical advance involves the coordination of four major instruments – including the world’s most advanced ‘adaptive optics’ system, which can make millions of tiny adjustments every second to it’s internal mirrors for optimal imaging.
These techniques can reveal planets one to even ten million times fainter than the star at the centre of the image, after only an hour of observation.
Scientists have described some of the results from this initial study as 'quite strange', as the exoplanets are 'redder', emitting longer wavelengths of light, than celestial objects with similar temperatures.
They say the observed phenomenon could be explained by significant but patchy cloud cover on the planets.
There is also an intriguing chemical imbalance in that the planets contain either ammonia or methane, but not both, running counter to basic laws of chemistry given the atmospheric temperatures.
These bizarre observations could be down to the brightness and huge amount of UV light shone by HR 8799, the star at the centre of the system, which could affect the chemical ‘spectra’ of the planets, possibly causing complex weather such as dense carbon fog, the researchers said.
They are already collecting more data on this system to look for changes in the planets over time, as well as surveying other young stars.
During its three-year survey at Palomar, which started in June, Project 1640 aims to survey 200 stars within about 150 light years of our solar system.
A detailed description of the study is due to be published in The Astrophysical Journal.
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Magnetic fields easily penetrate matter. Creating a space practically devoid of magnetic fields thus presents a great challenge. An international team of physicists has now developed a shielding that dampens low frequency magnetic fields more than a million-fold. Using this mechanism, they have created a space that boasts the weakest magnetic field of our solar system.
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Yellowstone is no ordinary volcano. Three times in the last couple of million years, this so-called supervolcano, located in the western US, has blown itself apart in some of the biggest explosions ever known.
The last, which happened around 630,000 years ago, pumped out enough ash to cover most of the country, and left behind a giant crater – the Yellowstone Caldera – more than 70km (44 miles) across.
The huge volumes of sulphur gas blasted into the atmosphere by the eruption would have blotted out the Sun, causing global temperatures to plunge and spawning a volcanic winter that lasted for several years.
But Yellowstone is still restless. Earthquakes are common, the ground repeatedly swells and sinks, and the area is peppered with boiling springs, mud pots and geysers.
A gigantic body of magma still lurks beneath the volcano, so another massive eruption could happen some time in the future. There are concerns that the resulting volcanic winter might destroy our civilisation, but not if we can take action to try and stop it first.
And that’s just what Brian Wilcox and a team of researchers at NASA’s Jet Propulsion Laboratory have proposed. The idea is to drill into Yellowstone to ‘let off steam’.
I’ve often been asked about this particular solution, and my answer has always been that such a venture would be akin to sticking a drawing pin in an elephant’s bottom. In other words, the effect would be pretty much zero.
But NASA has given the idea a little more thought and come up with something that might actually work. This is geoengineering on a huge scale.
In NASA’s plan, the drawing pin becomes an 8km-deep borehole drilled into Yellowstone’s hydrothermal system. This is the vast body of hot groundwater that surrounds the magma chamber and feeds the springs and geysers. The hydrothermal system absorbs more than two-thirds of the heat generated by the magma.
In NASA’s scheme, huge quantities of cold water would be pumped down the borehole, helping the hydrothermal system suck out even more heat; the idea being that the magma would cool, get stickier, and start to congeal. This, in turn, would mean that it was too viscous to rise towards the surface and feed an eruption.
If Yellowstone were ready to blow, it would need to be cooled by 35 per cent to stop the eruption in its tracks, and this wouldn’t come cheap. NASA estimates the cost would be $3.5bn (£2.4bn). It would take hundreds, or even thousands, of years to accomplish, which is a long time to keep the politicians who hold the purse strings on board.
Wilcox acknowledges that this would not be easy, and cautions against doing anything without a detailed study of the pros and cons. “I think it would be unlikely and even foolish to attempt this at any scale, unless a thorough
modelling effort had been conducted which shows that the possibility of triggering an eruption was low, almost zero,” he says.
But there’s good news. Superheated water, returned to the surface via the borehole, could be used to drive turbines and generate energy for the region, which could cover much of the cost.
“If it appears possible that economically competitive geothermal power could be produced as part of the ‘defanging’ of a supervolcano, [this] could close the economic equation sufficiently that people might attempt it,” Wilcox observes, perhaps a little optimistically.
There are dangers, of course, and there’s the possibility that drilling into a volcano that’s primed and ready to go might trigger the blast it’s trying to prevent. But with the catastrophic consequences for humans of a future super-eruption, it may turn out to be a risk we have to take.
How it works
NASA wants to pump water into the Yellowstone volcano to make the magma too sticky to rise.
- An 8km-deep borehole is drilled into the hydrothermal system.
- This vast body of hot groundwater surrounds the shallow magma chamber and absorbs more than two-thirds of the heat generated there.
- Huge quantities of water are pumped down the borehole, cooling the hydrothermal fluids so that they can suck out even more of the magma’s heat.
- The magma cools and starts to congeal, making it more difficult for it to reach the surface and feed an eruption.
- Superheated water returned to the surface via the borehole could be used to drive turbines and generate electricity.
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Spectroscopy of Damaged DNA
UV, fluorescence, circular dichroism, NMR, and other spectroscopic approaches can be used to study the properties of modified DNA (usually at the oligonucleotide level).
Long pieces of DNA with modifications are generally not very amenable to spectroscopy in that the spectral properties of the unmodified DNA bases obscure those of the damaged lesion. Most sophisticated spectroscopic studies have been done with oligonucleotides ≤18 bases in length and include ultraviolet (UV), fluorescence, circular dichroism (CD), and NMR studies. The synthesis of modified oligonucleotides is discussed under “Synthesis of Modified Oligonucleotides.”
KeywordsCircular Dichroism Spectrum Linear Dichroism Polycyclic Hydrocarbon Pyrene Derivative Spectroscopic Approach
- Zang H, Goodenough AK, Choi JY et al (2005) DNA adduct bypass polymerization by Sulfolobus solfataricus DNA polymerase Dpo4: analysis and crystal structures of multiple base pair substitution and frameshift products with the adduct 1, N2-ethenoguanine. J Biol Chem 280:29750–29764PubMedCrossRefGoogle Scholar | <urn:uuid:860696f6-b2a5-4935-835c-1253cadfe69b> | 2.796875 | 267 | Academic Writing | Science & Tech. | -6.699541 | 95,492,057 |
Underwater sound linked to human activity could alter the behaviour of seabed creatures that play a vital role in marine ecosystems, according to new research from the University of Southampton.
The study, reported in the journal Scientific Reports published by Nature, found that exposure to sounds that resemble shipping traffic and offshore construction activities results in behavioural responses in certain invertebrate species that live in the marine sediment.
These species make a crucial contribution to the seabed ecosystem as their burrowing and bioirrigation activities (how much the organism moves water in and out of the sediment by its actions) are crucial in nutrient recycling and carbon storage.
The study showed that some man-made sounds can cause certain species to reduce irrigation and sediment turnover. Such reductions can lead to the formation of compacted sediments that suffer reduced oxygen, potentially becoming anoxic (depleted of dissolved oxygen and a more severe condition of hypoxia), which may have an impact on seabed productivity, sediment biodiversity and also fisheries production.
Lead author Martin Solan, Professor in Marine Ecology, said: "Coastal and shelf environments support high levels of biodiversity that are vital in mediating ecosystem processes, but they are also subject to noise associated with increasing levels of offshore human activity. Previous work has almost exclusively focussed on direct physiological or behavioural responses in marine mammals and fish, and has not previously addressed the indirect impacts of sound on ecosystem properties.
"Our study provides evidence that exposing coastal environments to anthropogenic sound fields is likely to have much wider ecosystem consequences than are presently understood."
The Southampton researchers exposed three species - the langoustine (Nephrops norvegicus), a slim, orange-pink lobster which grows up to 25 cm long, the Manila clam (Ruditapes philippinarum) and the brittlestar (Amphiura filfiformis) ¬- to two different types of underwater sound fields: continuous broadband noise (CBN) that mimics shipping traffic and intermittent broadband noise (IBN) reflecting marine construction activity.
The sounds were reproduced in controlled test tanks and experiments were run on one species at a time. For CBN, a recording (one minute duration, continuously looped) of a ship made in the English Channel at a distance of around 100 metres was used'. For IBN, a recording (two minutes duration, continuously looped) of a wind farm in the North Sea at a distance of about 60 metres was used.
The results showed that the sounds could alter the way these species behaved when interacting with their environments.
With the langoustine, which disturbs the sediment to create burrows in which it lives, the researchers saw a reduction in the depth of sediment redistribution (how much of the surface sediment was overturned into the deeper layers) with exposure to IBN or CBN. Under CBN and IBN there was evidence that bioirrigation increased.
The Manila clam, a commercial fishery species in Europe that lives in the sediment and connects to the overlying water through a retractable siphon, reduced its surface activity under CBN, which affected the surface roughness of the sediment. Bioirrigation, which is strongly influenced by clam behaviour and the activity of the siphon, was markedly reduced by CBN and slightly reduced under IBN.
However, the sound fields had little impact on the brittlestar.
Co-author Dr Chris Hauton, Associate Professor in Invertebrate Ecophysiology and Immune Function, said: "I think these findings raise the prospect that anthropogenic sounds in the marine environment are impacting marine invertebrate species in ways that have not been previously anticipated. The potential effects of anthropogenic noise on ecosystem function, mediated through changes in organism behaviour merits further study as, in the long term, it may identify impacts to the productivity of seabed systems that have, to date, not really been constrained."
Tim Leighton, Professor of Ultrasonics and Underwater Acoustics and study co-author, added: "There has been much discussion over the last decade of the extent to which whales, dolphins and fish stocks, might be disturbed by the sounds from shipping, windfarms and their construction, seismic exploration etc. However, one set of ocean denizens has until now been ignored, and unlike these other classes, they cannot easily move away from loud man-made sound sources. These are the bottom feeders, such as crabs, shellfish and invertebrates similar to the ones in our study, which are crucial to healthy and commercially successful oceans because they form the bottom of the food chain.
Glenn Harris | EurekAlert!
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
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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The North American monsoon, variously known as the Southwest monsoon, the Mexican monsoon, the New Mexican monsoon, or the Arizona monsoon, is a pattern of pronounced increase in thunderstorms and rainfall over large areas of the southwestern United States and northwestern Mexico, typically occurring between July and mid September. During the monsoon, thunderstorms are fueled by daytime heating and build up during the late afternoon-early evening. Typically, these storms dissipate by late night, and the next day starts out fair, with the cycle repeating daily. The monsoon typically loses its energy by mid-September when drier and cooler conditions are reestablished over the region. Geographically, the North American monsoon precipitation region is centered over the Sierra Madre Occidental in the Mexican states of Sinaloa, Durango, Sonora and Chihuahua.
The North American Monsoon is not as strong or persistent as its Indian counterpart, mainly because the Mexican Plateau is not as high or as large as the Tibetan Plateau in Asia. However, the North American Monsoon shares most of the basic characteristics of its Indian counterpart. There is a shift in wind patterns in summer which occurs as Mexico and the southwest U.S. warm under intense solar heating. As this happens, the flow reverses. The prevailing winds start to flow from moist ocean areas into dry land areas.
The North American monsoon is associated with an area of high pressure called the subtropical ridge that moves northward during the summer months and a thermal low (a trough of low pressure which develops from intense surface heating) over the Mexican Plateau and the Desert Southwest of the United States. The monsoon begins in late May to early June in southern Mexico and quickly spreads along the western slopes of the Sierra Madre Occidental, reaching Arizona and New Mexico in early July. The monsoon extends into the southwest United States as it matures in mid-July, when an area of high pressure, called the monsoon or subtropical ridge, develops in the upper atmosphere over the Four Corners region, creating wind flow aloft from the east or southeast.
Pulses of low level moisture are transported primarily from the Gulf of California and eastern Pacific. The Gulf of California, a narrow body of water surrounded by mountains, is particularly important for low-level moisture transport into Arizona and Sonora. Upper level moisture is also transported into the region, mainly from the Gulf of Mexico by easterly winds aloft. Once the forests of the Sierra Madre Occidental green up from the initial monsoon rains, evaporation and plant transpiration can add additional moisture to the atmosphere which will then flow into Arizona. Finally, if the southern Plains of the U.S. are unusually wet and green during the early summer months, that area can also serve as a moisture source.
As precipitable water values rise in early summer, brief but often torrential thunderstorms can occur, especially over mountainous terrain. This activity is occasionally enhanced by the passage of tropical waves and the entrainment of the remnants of tropical cyclones.
Monsoons play a vital role in managing wildfire threat by providing moisture at higher elevations and feeding desert streams. Heavy monsoon rain can lead to excess winter plant growth, in turn a summer wildfire risk. A lack of monsoon rain can hamper summer seeding, reducing excess winter plant growth but worsening drought.
Flash flooding is a serious danger during the monsoon. Dry washes can become raging rivers in an instant, even when no storms are visible as a storm can cause a flash flood tens of miles away; it is therefore wise to avoid camping in a dry wash during the monsoon. Lightning strikes are also a significant danger. Because it is dangerous to be caught in the open when these storms suddenly appear, many golf courses in Arizona have thunderstorm warning systems.
Rainfall during the monsoon is not continuous. It varies considerably, depending on a variety of factors. There are usually distinct "burst" periods of heavy rain during the monsoon, and "break" periods with little or no rain. Monsoon precipitation, however, accounts for a substantial portion of annual precipitation in northwest Mexico and the Southwest U.S. Most of these areas receive over half their annual precipitation from the monsoon.
The North American Monsoon circulation pattern typically develops in late May or early June over southwest Mexico. By mid to late summer, thunderstorms increase over the "core" region of the southwest U.S. and northwest Mexico, including the U.S. and Mexican states of Arizona, New Mexico, Sonora, Chihuahua, Sinaloa and Durango. The monsoon typically arrives in mid to late June over northwest Mexico, and early July over the southwest U.S. Once the monsoon is underway, mountain ranges, including the Sierra Madre Occidental and the Mogollon Rim provide a focusing mechanism for the daily development of thunderstorms. Thus much of the monsoon rainfall occurs in mountainous terrain. For example, monsoon rainfall in the Sierra Madre Occidental typically ranges from 10 to 15 inches. Since the southwest U.S. is at the northern fringe of the monsoon, precipitation is less and tends to be more variable. Areas further west of the core monsoon region, namely California and Baja California, typically receive only spotty monsoon-related rainfall. In those areas, the intense solar heating is not strong enough to overcome a continual supply of cold water from the North Pacific Ocean moving down the west coast of North America. Winds do turn toward the land in these areas, but the cool moist air actually stabilizes the atmosphere. The monsoon pushes as far west as the Peninsular Ranges and Transverse Ranges of southern California, but rarely reaches the coastal strip. As shown in the panorama below, a wall of thunderstorms, only a half-hour's drive away, is a common sight from the sunny skies along the coast during the monsoon.
This monsoon ridge is almost as strong as the one which develops over Asia during the summer. However, since the lower level moisture flow is not as persistent as in the Indian monsoon, the upper level steering pattern and disturbances around the ridge are critical for influencing where thunderstorms develop on any given day. The exact strength and position of the subtropical ridge also governs how far north the tropical easterly winds aloft can spread. If the ridge is too close to a particular area, the sinking air at its center suppresses thunderstorms and can result in a significant monsoon "break." If the ridge is too far away or too weak, the east winds around the high are inadequate to bring tropical moisture into the mountains of Mexico and southwest U.S. However, if the ridge sets up in a few key locations, widespread and potentially severe thunderstorms can develop.
Unlike the Pacific region of the United States and the west coast of Baja California, precipitation in the North American monsoon is not associated with large-scale mid-latitude cyclones, but with thunderstorms which have very different spatial/temporal distribution characteristics. The difficulty in understanding the variability of summertime convective activity in the southwestern U.S. and northwestern Mexico results from the complex interactions between atmospheric circulation features at both the synoptic (100 to 1000 km spatially, 1 day to 1 week, temporally) and mesoscale (several km to 100 km, hours to one day temporally) and the extremely varied topography. The larger-scale atmospheric motions may control the distribution of water vapor and the general stability or instability (that is, the tendency to form storms) in the atmosphere; nevertheless, local topographic effects are critical to the geographic and even temporal distribution of convective activity. | <urn:uuid:09a365b7-2650-4b4a-b2e6-4e0a46add0c4> | 4.25 | 1,586 | Knowledge Article | Science & Tech. | 35.121169 | 95,492,070 |
Cosmogenic21Ne was utilised to determine exposure ages of young subaerial basaltic lava flows from the Newer Volcanic Province, western Victoria, Australia. The ages (36-53 ka) determined from co-existing cosmogenic21Ne and3He in olivines separated from basalts are consistent within analytical uncertainties with ages previously determined by cosmogenic36Cl exposure dating. This paper illustrates the potential of cosmogenic neon exposure ages in studying the eruption, surface morphology, and erosion history of young volcanic rocks, which are difficult to date using other conventional methods, such as K-Ar or40Ar/39Ar dating. The present study demonstrates that combined cosmogenic3He and21Ne dating, specifically measured cosmogenic3He/21Ne ratios, on the same samples, is powerful for evaluating the validity of calculated cosmogenic3He and21Ne surface exposure ages. © 2009 Elsevier B.V. All rights reserved.
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For 500 ml of solution of .5M acetic acid at pH 4.6, how many moles of HCl (assume no volume change) would have to be added to get the salt to acid ratio as 1/8?
pKa of acetic acid is 4.76.
Your question relates to buffers, or solutions which resist changes in pH. Buffers are often used in biochemistry and chemistry and typically are made with a weak acid (only partially dissociates in water) and a soluble salt containing the acid's conjugate base. There are literally hundreds of different buffer systems; each buffer is most useful in the pH range at or close to a value known as the pKa. This is the negative Log (base 10) of the Ka, which is the dissociation constant for the weak acid. In order to calculate pH values of buffers or the amounts of each constituent required for a specific buffer, we need to know the pKa.
The solutions to your questions involve the Henderson-Hasselbalch (H-H) equation (for a derivation of this equation plug ...
The solution solves for the proper amount of HCl to be added to a buffer solution to achieve a required salt acid ratio. | <urn:uuid:300a6b16-8a64-4140-a9ce-cc622d7052c6> | 2.609375 | 254 | Q&A Forum | Science & Tech. | 61.628 | 95,492,078 |
This is as straightforward of an example as possible of sensor fusion between a GPS and an accelerometer using a kalman filter.
go run kalmanFilter.go
For corresponding video, visit: YouTube Video
The above file is some sample data using a GPS and an accelerometer. Previous work extracted out gravity, and resultant quaternion from gyroscope and magnetomer was used to create readings for absolute acceleration in North, East, and Up. How to ascertain those values is outside the scope of this project, but if you'd like help with that feel free to contact me.
The code itself is an API to fuse accelerometer and GPS data together in an extremely common scenario for using a kalman filter. The
taco_bell_data.json is the input file, and an output file is produced that includes the estimated velocity and position at each sample without the aid of GPS.
There are additional helper functions in the file to translate GPS data to meters. | <urn:uuid:35c2f090-b90c-4acc-8f4f-47032b7b4434> | 2.765625 | 202 | Documentation | Software Dev. | 38.625556 | 95,492,094 |
> I'm used to sprinkling print statements in my code as a way of tracking
> down bugs but they seem to be affecting my code more than I was expecting.
I recommend to look at 'trace' and 'msg'. They both output to stderr and don't
interfer with the expressions.
'trace' shows what argumments are passed, and what the functions return. See the
tutorial for examples.
'msg' prints its argument to stderr *and* returns it, so it does not destroy the
flow. For example:
Now this would be wrong:
But this is all right:
(if (msg (condition) " condition")
(msg (doTrue) " true")
(msm (doFalse1) " false")
Even easier is not to modify the source at all, and do instead, before starting
(mapc trace '(condition doTrue doFalse1))
And/or use 'debug' to single-trace your program. Again see the tutorial.
> I've also realised I'm never quite sure when and when I shouldn't precede a
> symbol with a quote e.g. as a function argument in a (debug 'Symbol)
> statement and wonder if there are some very simple rules of thumb.
It is noted in the reference. If an argument is noted as eg. 'any it means that
the argument is *evaluated* (not necessarily that you actually need to write a | <urn:uuid:ea6cadd4-0dfa-44fe-bb6b-d1133bd1d059> | 2.90625 | 314 | Comment Section | Software Dev. | 64.747418 | 95,492,116 |
- Written by Marcelo Nigro
- Hits: 6992
Each one has its own strengths and weaknesses, and specific areas of application, allowing you to choose based on the needs of a specific project. Also, many of the options are modular, allowing you to use only the components you need, or even mix components from different frameworks.
I'll consider in other article provide some good, practical examples of techniques that make the most out of the integration of these valuable frameworks.
But maybe some overview at first.
But, there are many frameworks out there that try to lead the complexities of web application development to varying degrees of success. Here it would be fine to state a difference between frameworks and libraries, the choice will influence your architecture. I mean libraries fit into your existing architecture adding specific functionality, however frameworks give you an architecture (file structure, etc.) that you have to follow.
So, what makes AngularJS different? Let me offer a few opinions.
The last year I’ve been working on a big project using AngularJS and I’ve become very impressed with the clarity it brings to developing enterprise-level web applications.
I’ve done a lot of development on both Windows and the Web. I’ve enjoyed writing desktop applications but writing web applications never seemed to fit into a similar simple but effective model. I think, the model that AngularJS defines feels familiar and comfortable.
Now let’s have a closer look at all those features.
They divide your web application into small, reusable and functional components which can be integrated with other web applications. Each module is identified by a unique name and can be dependent on other modules.
They define the actual behavior of your app. It contains business logic for the view and connects the right models to the right views. A controller is associated with a HTML element with the ng-controller directive.
They are used to extend the HTML vocabulary i.e they decorate html elements with new behaviors and help to manipulate html elements attributes in interesting way. There are some built-in directives provided by angularjs like as ng-app, ng-controller, ng-repeat, ng-model etc.
They are just plain old HTML that contains Angular-specific elements and attributes. AngularJS used these templates to show information from the model and controller.
It’s an object that refers to the application model. It acts as a context for evaluating expressions. Typically, it acts as a connector between controller and view. Scopes are hierarchical in nature and follow the DOM structure of your angularjs app.
It’s the most useful feature which save you from writing a considerable amount of code. Now, developers are not responsible for manually manipulating the DOM elements and attributes to reflect model changes.
It enables you to develop a modern HTML5 form that is interactive and responsive. AngularJS provides you built-in validation directives to achieve form validation and they are based on the HTML5 form validators.
They are used to format data before displaying it to the user. They can be used in view templates, controllers, services and directives. There are some built-in filters provided by angularjs like as Currency, Date, Number, OrderBy, Lowercase, Uppercase etc.
They are reusable singleton objects that are used to organize and share code across your app. They can be injected into controllers, filters, directives.
It helps you to divide your app into multiple views and bind different views to Controllers. The magic of Routing is taken care by an angularjs service $routeProvider, that provides method .when() and .otherwise() to define the routes for your app.
It’s a software design pattern that deals with how components get hold of their dependencies. AngularJS comes with a built-in dependency injection mechanism.
It’s designed to be testable so that you can test your AngularJS applications as easy as possible. It also comes with an end-to-end and unit test runner setup.
I’m not implying, of course, that AngularJS perfectly matches up to WPF programming, but the similarities are appealing. More importantly, the model that AngularJS provides should help developers to be more productive.
Although Angular already provides a large part of the functionality needed to build the frontend of our app, a good complement is to have an easily themeable CSS library. Nowadays there are several CSS front-end frameworks, but the number of really good ones can be counted on the fingers of one hand, being Bootstrap the most popular.
Bootstrap is the undisputed leader among the available frameworks today, given its huge popularity, which is still growing every day.
Although technically it’s not necessarily better than the others in the list, it offers many more resources (articles and tutorials, third-party plug-ins and extensions, theme builders, and so on) than the other frameworks combined. However, this popularity also has a small downside, sites that use default themes may end up looking very similar between them.
Bootstrap is 12 grid CSS framework, by grids I mean that logically divide the canvas area of the webpage into 12 columns. You can decide how much area an element can consume by assigning the number of columns to it. Using the grid systems helps in making the website responsive, which means anything you do using Bootstrap will be compatible with all screen sizes devices, because of this it is commonly called Mobile First CSS framework.
Undoubtedly one of the biggest advantages of using Bootstrap is the speed of development. The framework allows for rapid, responsive development that is consistent and well supported by the development and design community, and as the framework continues to develop, the reasons to use Bootstrap keep mounting.
In short, Bootstrap is everywhere. And this is the main reason people continue to choose it.
Why ASP.NET MVC?
ASP.NET MVC is a robust and mature platform for creating enterprise-level web applications, but there are of course other platforms out there that might be more appealing. Should one consider a Microsoft platform over another alternative?
I would summarize my answer to this as follows:
- The .NET runtime is a very mature, well understood framework that remains very popular.
- The ASP.NET MVC framework provides a good, easy-to-use abstraction over web protocols, including web APIs.
- The platform is highly extensible. Parts of the framework can be easily replaced as necessary in order to provide enhanced functionality.
- Microsoft has continued to strengthen the platforms that ASP.NET MVC builds upon in Windows Server and SQL Server.
- ASP.NET MVC provides a good testing story.
The purpose is not to be a salesman for Microsoft technologies, but I think that ASP.NET MVC is a strong platform for building enterprise web applications.
Why AngularJS, Bootstrap and ASP.NET MVC?
As we all know, web development has moved forward. Whereas before we might create beautiful Flash or Silverlight applications to enhance the user’s web experience, those days are unfortunately gone. With the preponderance of devices using the web, we can’t depend on plug-ins to drive our applications.
Web standards have also moved forward. HTML5 and CSS3 are now the new goal posts for building an enhanced web experience. SPA (single-page applications) are the new normal, form-intensive enterprise class applications are ideally suited for being built on this standard.
The main idea compared to other more traditional server-side architectures is to build the server as a set of stateless reusable REST services, and from an MVC perspective to take the controller out of the backend and move it into the browser:
The client is MVC-capable and contains all the presentation logic which is separated in a view layer, a controller layer and a frontend services layer. After the initial application startup, only JSON data goes over the wire between client and server.
Therefore the robustness of the ASP.NET MVC platform needs an equally robust client framework and I am convinced that AngularJS and Bootstrap are and will be great partners.
About Marcelo Nigro
Marcelo is a Software Engineer with more than 20 years of experience developing Web and Desktop applications for some of the most important Fortune 500 companies
Nowadays Marcelo specializes in leading the R&D department of TISA, looking for implementing the latest technologies and frameworks to be used in future projects.
Beyond his technical knowledge and passion for the technology Marcelo enjoys playing Ping-Pong and is half marathon runner, he also like listening musing from the 90's. | <urn:uuid:72dc1080-8780-4432-85c7-6503dc87e653> | 2.84375 | 1,777 | Personal Blog | Software Dev. | 41.594901 | 95,492,152 |
Effects of Water Vapor on Cryogenic Wind Tunnels
Cryogenic wind tunnels are capable of testing at flight equivalent conditions on scaled models to obtain full size results. To reach cryogenic temperatures the gas and much of the tunnel mass is cooled by injecting liquid nitrogen into the tunnel. During the cooling from ambient to cryogenic temperatures the thermal stress, liquid nitrogen consumption, time, and test gas dew point are critical to insure uniform and good flow quality in the test section. The dew point is critical because it shows the amount of water vapor within the tunnel circuit. A cooldown is not a problem if the gas dew point is low (< 233K) before the gas temperature drops below the dew point. If the dew point is not low while cooling, frost will from on the model and sections of the tunnel. This paper examines the sources of water vapor in a cryogenic wind tunnel, the effects it has on the tunnel operation, and the methods to manage the water vapor. The tunnel used in this study is the U.S. National Transonic Facility located at NASA Langley. Research Center.
KeywordsWater Vapor Mach Number Wind Tunnel Test Section Cryogenic Temperature
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- 1.W. Igoe, Characteristics and Status of the U.S. National Transonic Facility, AGARD Lecture Series No. 111, Cryogenic Wind Tunnels, (July 1980).Google Scholar
- 2.D.E. Fuller, Guide for Users of the National Transonic Facility, NASA TM 83124, (July 1983).Google Scholar
- 3.B.B. Gloss and W.E. Bruce, A Solution to Water Vapor in the National Transonic Facility, 27th Aerospace Sciences Meeting, AIAA 89-0152, (January 1989)Google Scholar
- 4.W.E. Bruce and B.B. Gloss, The U.S. National Transonic, NTF, AGARD Report No. 774, Special Course on Advances in Cryogenic Wind Tunnel Technology, (June 1989)Google Scholar
- 5.B. Sthal, Investigation on the Formation of Ice Crystals in the Cryogenic Wind Tunnel, Colonge, Wind Tunnels and Wind Tunnel Test Techniques, The Royal Aeronautical Society, Paper No. 24, (September 1992)Google Scholar
- 6.A. Blanchard, J.B. Dor, and A. Seraudie, New Testing Techniques in the T2 Cryogenic Wind Tunnel, Wind Tunnels and Wind Tunnel Test Techniques, The Royal Aeronautical Society, Paper No. 22, (September 1992)Google Scholar
- 7.R.B. Zwicker, National Transonic Facility, Facility Description Document, Section D, D-17, (September 1986)Google Scholar | <urn:uuid:3d0358b9-4cf9-4e8d-9150-ee244c35f834> | 3.28125 | 577 | Academic Writing | Science & Tech. | 61.315943 | 95,492,154 |
A new study carried out by an international team of researchers led by Carnegie's Wolf Frommer, David Ehrhardt, and Guido Grossmann and including those from Stanford, Regensburg, Heidelberg and Munich has shed new light on the chemical signaling process that plays a crucial role in flowering plant fertilization.
It is published in Nature Communications
. Flowering plants have a double fertilization system. Grains of pollen carry the male reproductive cells. When pollen grains land on the flower's female reproductive organ, they germinate and grow towards the deeply embedded ovules via a pollen tube. After fertilization, ovules develop into seeds. What makes the process unique is that the pollen tube releases two sperm cells, one of which fuses with an egg in a process like that in animals.
The other fuses with the so-called central cell to form a multi-nuclear entity that grows and provides nutrition for the developing embryo and seedling, respectively. This so-called endosperm is also the major source of nutrition for the animals and humans that eat these plants. Numerous cell-to-cell chemical interactions are necessary to guide this process as it takes place, many of which remain unidentified. In animals, calcium is key for communication between cells during fertilization.
The research team, led by Thomas Dresselhaus from the University of Regensburg and Guido Grossmann, who recently moved from Carnegie to the University of Heidelberg, focused on finding calcium-facilitated communication in the double fertilization of flowering plants. It was already known that calcium is involved in the early stages of fertilization, including pollen tube growth control and the guidance that brings the sperm to the ovule. But more work was necessary to determine if it was as important in the later stages. Using an advanced fluorescent calcium sensor the team was able to monitor calcium signatures in live cells throughout the whole double fertilization process. The work was performed using Arabidopsis, which is commonly used for research purposes. They found that calcium was involved in chemical signaling throughout the double fertilization process and is associated, for example, with sperm release and fusion with the egg cell. This type of real-time observation had previously been impossible due to the deeply imbedded location where double fertilization occurs. "Thanks to technical advances we were able to observe the moment of plant fertilization at the cellular level and, at the same time, listen to the 'tête-à-tête' between male and female cells," Grossmann said. "Further work is necessary to decode the language and understand what is actually being said." | <urn:uuid:beeb7581-740a-4d86-8572-021ebf179fde> | 3.859375 | 532 | News Article | Science & Tech. | 29.403191 | 95,492,156 |
Also found in: Thesaurus, Encyclopedia, Wikipedia.
1. A differential or partial differential equation used to represent wave motion.
2. The fundamental equation of wave mechanics.
(General Physics) physics a partial differential equation describing wave motion. It has the form ∇2φ = (1/c2) × (∂2φ/∂t2), where ∇2 is the Laplace operator, t the time, c the speed of propagation, and φ is a function characterizing the displacement of the wave | <urn:uuid:bc2a09f4-01f7-4f41-9660-05ee88ec8681> | 2.65625 | 113 | Structured Data | Science & Tech. | 44.353804 | 95,492,182 |
The Ionosphere as a Plasma
A plasma represents a collection of charged particles (electrons and ions) which interact by long range (Coulomb) forces, exhibiting coherent behavior as the result of space charge effects .
KeywordsPolarization Field Scale Height Ionospheric Plasma Neutral Wind Ambipolar Diffusion
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As the term is understood by mathematicians, folk mathematics or mathematical folklore is the body of theorems, definitions, proofs, or mathematical facts or techniques that circulate among mathematicians by word of mouth but have not appeared in print, either in books or in scholarly journals. Knowledge of folklore is the coin of the realm of academic mathematics.[original research?]
Quite important at times for researchers are folk theorems, which are results known, at least to experts in a field, and considered to have established status, but not published in complete form. Sometimes these are only alluded to in the public literature. An example is a book of exercises, described on the back cover:
Another distinct category is wellknowable mathematics, a term introduced by John Conway. This consists of matters that are known and factual, but not in active circulation in relation with current research. Both of these concepts are attempts to describe the actual context in which research work is done.
Some people, principally non-mathematicians, use the term folk mathematics to refer to the informal mathematics studied in many ethno-cultural studies of mathematics.
Stories, sayings and jokes
|Wikiquote has quotations related to: Mathematics|
|Wikiquote has quotations related to: Mathematicians|
Mathematical folklore may also refer to unusual (and possibly apocryphal) stories or jokes involving mathematicians or mathematics that are told verbally in mathematics departments. Compilations include tales collected in G. H. Hardy's A Mathematician's Apology and (Krantz 2002); examples include:
- Galileo dropping weights from the Leaning Tower of Pisa.
- An apple falling on Isaac Newton's head to inspire his theory of gravitation.
- The drinking, duel and early death of Galois.
- Richard Feynman cracking safes in the Manhattan Project.
- Alfréd Rényi's definition of a mathematician: "a device for turning coffee into theorems".
- The "turtles all the way down" story told by Stephen Hawking.
- Fermat's lost simple proof.
- The unwieldy proof and associated controversies of the Four Color Theorem.
- Grigore Calugareau & Peter Hamburg (1998) Exercises in Basic Ring Theory, Kluwer,[[[International Standard Book Number|ISBN]] 0792349180] | <urn:uuid:220d863a-a77d-4f5c-8ffa-16e754abeaaa> | 3.34375 | 491 | Knowledge Article | Science & Tech. | 28.591176 | 95,492,205 |
Ice storms not necessarily bad
While the study is still ongoing, first results from the experimental forest are already in. A light ice shower could be beneficial for the forest, because a thin layer of ice kills surplus sprouts so other branches have more room. Since trees store a certain amount of carbon, they can survive under ice for a little while. But strong, frequent ice storms would be a threat. | <urn:uuid:6c3be459-3348-4341-8c4f-354af0aa3eb8> | 2.734375 | 81 | Truncated | Science & Tech. | 51.790581 | 95,492,206 |
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Warm waters have pushed certain kinds of whales into unstable habitats, leading to a steep decline in births, a new study found.
North Atlantic whales are facing extinction, experts say, after observing no sign of newborns in the past year.
As the ocean water temperatures have risen, depleting their food supply, the whales have been migrating to cooler waters where new hazards and "nutritional stress" are taking a toll on their population size, a March study out of Cornell University said.
Whales are now venturing farther north into cooler Canadian waters where food is more plentiful, but where boats and fishing gear have proved dangerous.
“The fishing gear has not been specially designed to break away when whales are entangled, and there are no acoustic monitoring programs in place to force ships to slow down when whales are present,” said Charles Greene, professor of oceanography at Cornell University.
Researchers said 17 right whales died last year, totaling more than 3.5 percent of the population. Right whales refer to three types of Eubalaena whales - the North Atlantic right whale, North Pacific right whale and the Southern right whale.
“Most of the dead whales that have been examined have exhibited evidence of the blunt trauma associated with ship strikes," Greene said.
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Right whales eat Calanus finmarchicus, a species of copepods as their main form of nutrition. Scientists have tracked whale reproduction rates in correlation with the amount of available C. finmarchicus. Whale reproduction can vary greatly, Greene said, depending on the abundance of the copepods.
Recently, the researchers grew concerned with the spread of C. finmarchicus away from the Gulf of Maine as water temperatures rose, bringing the whales with them.
These northern waters are not safe for the whales, and the added "nutritional stress" has likely led to the decline in new calves.
"This elevated mortality in the population paints a bleak picture for this highly endangered species’ future,” he said.
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An 11-million ton iceberg hovers over the town of Innaarsuit in Greenland. The massive iceberg floats dangerously close to shore, threatening the small town.
Two people suffered shark bites while swimming in the water off Fire Island in Suffolk County, New York, according to NBC New York.
Newly formed Tropical Storm Ampil is set to strengthen as it tracks toward Japan’s Ryukyu Islands later this week.
A rainstorm moving up from the south will coincide with a shift in the jet stream and mark the beginning of an extended period of wet, humid conditions in the northeastern US that may last into August.
Eventualmente, la aspirante a ingeniero ambiental espera trabajar tanto con gobiernos como con corporaciones para eliminar microplásticos de los océanos de manera segura y eficiente.
Drenching thunderstorms advanced into the northeastern United States Tuesday afternoon and evening, bringing reports of flash flooding throughout the region.
Weather invariably comes into play at certain points during the Tour de France, especially when some tour stages can be greater than 100 miles in length.
Heavy spring rainfall in parts of the mid-Atlantic have triggered higher-than-average mosquito rates this season. It is estimated that mosquitoes are two to three times their normal rates. | <urn:uuid:91822828-695a-40d8-8840-37b9a534262d> | 3.5625 | 784 | News Article | Science & Tech. | 33.914143 | 95,492,212 |
Scientists who are always on the lookout for some small sign that we are not alone in the universe have recently a couple of very small discoveries, that have them dreaming of big things. Biologists have found a new type of deep-sea anemone, at nearly the same time astronomers learned that stardust contains small pockets of water, two discoveries which suggest that extraterrestrial life in harsh conditions is very possible.
First, a research robot that is part of the National Science Foundation's ANDRILL Antarctic drilling program, went on a routine mission down an 885-foot deep hole drilled into the Ross Ice Shelf and discovered a new species of anemone that lives off ice. And not just a new lifeform, but a whole new way of living:
SCINI [the robot] detected signs of the all-new ecosystem, one containing the opaque-white, ethereal anemones, now named Edwardsiella andrillae. They're just 2.5-to-3 centimeters in size when contracted, and about four times longer when relaxed. Each of them have around 20-to-24 tentacles.
Researchers say they discovered tens of thousands of the anemones clinging to the ice.
According to the NSF, the discovery was first made back in 2010. While other anemones are known to live on or in the seafloor, these are unique in that the live on frigid ice and hang upside down — and are part of a whole new ecosystem:
In addition to the anemones, the scientists saw fish who routinely swam upside down, the ice shelf serving as the floor of their submarine world, as well as polychaete worms, amphipods and a bizarre little creature they dubbed "the eggroll", a four-inch-long, one-inch-diameter, neutrally-buoyant cylinder, that seemed to swim using appendages at both ends of its body, which was observed bumping along the field of sea anemones under the ice and hanging on to them at times.
The discovery is especially significant in the context of the recent discovery of water spouting from Europa. The anemones, which thrive in ice, could represent the type of life Europa, an ice covered ball with a liquid ocean underneath, could support.
A second, unrelated discovery shows that when charged wind from the sun hits stardust, a tiny pocket of water is formed within the interplanetary dust. Stardust has already been shown to contain certain organic compounds, which means that each grain of stardust potentially has the basic ingredients of life. Because such dust is likely prevalent all across the universe, it increases the likelihood of extraterrestrial life existing somewhere. Dr. Hope Ishii, part of the team of researchers who made the discovery, said it has "potentially huge" implications. She told NewScientist.com:
It is a particularly thrilling possibility that this influx of dust on the surfaces of solar system bodies has acted as a continuous rainfall of little reaction vessels containing both the water and organics needed for the eventual origin of life.
We hope this means more funding for science, and that we will one day meet alien anemone that will take us to Europa with them for vacation.
This article is from the archive of our partner The Wire.
We want to hear what you think. Submit a letter to the editor or write to firstname.lastname@example.org. | <urn:uuid:98804529-c86f-499d-8d8c-433c3363c43e> | 3.5625 | 706 | Truncated | Science & Tech. | 41.058955 | 95,492,216 |
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Objective 1: Study the History of Water in All its Phases
Currently, water on Mars' surface and atmosphere exists in two states: gas and solid. At the poles, the interaction between the solid water ice at and just below the surface and the gaseous water vapor in the atmosphere is believed to be critical to the weather and climate of Mars. Phoenix will be the first mission to collect meteorological data in the Martian arctic needed by scientists to accurately model Mars' past climate and predict future weather processes.
Liquid water does not currently exist on the surface of Mars, but evidence from Mars Global Surveyor, Odyssey and Exploration Rover missions suggest that water once flowed in canyons and persisted in shallow lakes billions of years ago. However, Phoenix will probe the history of liquid water that may have existed in the arctic as recently as 100,000 years ago. Scientists will better understand the history of the Martian arctic after analyzing the chemistry and mineralogy of the soil and ice using robust instruments.
Objective 2: Search for Evidence of Habitable Zone and Assess the Biological Potential of the Ice-Soil Boundary
Recent discoveries have shown that life can exist in the most extreme conditions. Indeed, it is possible that bacterial spores can lie dormant in bitterly cold, dry, and airless conditions for millions of years and become activated once conditions become favorable. Such dormant microbial colonies may exist in the Martian arctic, where due to the periodic wobbling of the planet, liquid water may exist for brief periods about every 100,000 years making the soil environment habitable.
Phoenix will assess the habitability of the Martian northern environment by using sophisticated chemical experiments to assess the soil's composition of life-giving elements such as carbon, nitrogen, phosphorus, and hydrogen. Identified by chemical analysis, Phoenix will also look at reduction-oxidation (redox) molecular pairs that may determine whether the potential chemical energy of the soil can sustain life, as well as other soil properties critical to determine habitability such as pH and saltiness.
Despite having the proper ingredients to sustain life, the Martian soil may also contain hazards that prevent biological growth, such as powerful oxidants that break apart organic molecules. Powerful oxidants that can break apart organic molecules are expected in dry environments bathed in UV light, such as the surface of Mars. But a few inches below the surface, the soil could protect organisms from the harmful solar radiation. Phoenix will dig deep enough into the soil to analyze the soil environment potentially protected from UV looking for organic signatures and potential habitability.
16 November 2007
The European Mars Science & Exploration Conference: Mars Express and ExoMars has just concluded.
We present interviews with selected experts on the hot topic: Mars and the search for traces of life. | <urn:uuid:a0562c7b-c3b0-4ca9-b5be-b0d75702c4c9> | 3.78125 | 612 | Comment Section | Science & Tech. | 26.888215 | 95,492,225 |
Ecologists may have captured the first deep-sea fish sounds, hidden among the sounds of dolphins and humpback, fin and pilot whales, they report in a new study.
More than 50 years ago, researchers hypothesized that sound production in deep-sea fish is common, based on the fact that many of the species have the anatomy needed to produce sound. Most fish make incidental noises as a byproduct of chewing and swimming, but for deep-sea fish, which live in perpetual darkness, communicative noises might be important for survival and reproduction.
"But just because they have the anatomy to make noises, doesn't mean they necessarily do it," said Rodney Rountree, a marine ecologist at the University of Massachusetts, Amherst. "In terms of communicative sounds, we don't know what proportion of the fish do it."
Few studies have ever reported recording possible deep-sea fish sounds, so scientists know little about these sounds, Rountree explained. It's not as simple as putting the fish in a tank and listening in on their conversations. "Deep-water fish are extremely difficult to keep alive in the lab, and the fish will not make a sound unless you can elicit the behavior tied to the sound," he told LiveScience. For example, you won't be able to hear their reproductive sounds unless you can get them to spawn in the laboratory, which they won't do unless the conditions are just right. [Video of Fish Calls]
Moreover, until now scientists have not pursued recording deep-sea fish in their natural habitat, mostly because of the lack of adequate, low-cost technology. "Our study was the first where we purposely went out and did that," Rountree said.
In collaboration with commercial fishermen, Rountree and his colleagues developed a simple deep-water hydrophone. With the device, they recorded 24 hours of deep-water sounds from the seafloor (about 2237 feet, or 862 meters, below the surface) of Welkers Canyon, which is south of New England's Georges Bank. From the recording, they were able to identify various sounds from whales and other cetaceans, but they also heard at least 12 other unique and unidentifiable sounds.
These mysterious grunts, drumming and duck-like calls could be from whales, but they could also have come from deep-sea fish. "Most fish only hear low frequencies and only produce low-frequency sounds," Rountree said. "The sounds we recorded were in the range that fish typically use."
If the sounds were indeed produced by deep-sea fish, the continued increases in man-made noise may prove to be problematic, Rountree said. The potential fish noises were just barely above the background noise, he said, "so if the background noise increases too high, it might mask the fish's sounds from each other."
Rountree and his team are now trying to develop a listening system that incorporates video, in hopes of identifying the creatures that made the enigmatic noises. However, the work has been difficult. "When we try to incorporate video, the price tag goes way up, because video requires light, and powering the light becomes a problem," Rountree said. "Right now we are still on the drawing board with trying to come up with a good way to do this."
They also hope to figure out the meaning behind the grunts and other calls.
The study appears in the new book, "Effects of Noise on Aquatic Life" (Springer, 2012).
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Copyright 2012 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. | <urn:uuid:e8b45433-cfa4-4e35-90d0-cb106c3b47b4> | 4.03125 | 785 | News Article | Science & Tech. | 48.252992 | 95,492,232 |
Oil and oil products spill often and in various places. These are plots in oil production areas and pipeline breaking locations and places of tanker wracks or crashes of consists, which carry oil products. At best, oil spillage falls on hard soil: it can be collected and somehow refined or, at the worst, buried. The case is much worse if the spillage takes place on water.
The oil film spreads out quickly to large distances, and it is very uneasy to collect. A thick film is removed by sea bulldozers by “scraping it off” water surface. As for a thin film, which produces iridescent spots, it is practically impossible to eliminate. By the way, its emergence does not require any disastrous events at all: a film may drift behind an ordinary motor-launch if its engine does not run well. A film several microns thick may seem to produce little impact. For water inhabitants, it emergence can mean certain death: it reduces oxygen dissolving in water drastically.
Therefore, the problem of fighting oil film is more than urgent. There is only one remedy for it: sorbent that is capable of taking in oil products. It is also desirable that the sorbent itself did not contaminate the environment and was able to turn carbohydrates into something quite harmless. Researchers of three institutes – Snezhinsk All-Russian Scientific Research Institite of Technical Physics (VNIITF), Novosibirsk State Research Center “Vector” and the Syktyvkar Institute of Biology (Komi Research Center, Ural Branch, Russian Academy of Sciences) with financial support from the International Science and Technology Center (ISTC) – managed to combine all three components of an ideal sorbent. Significant assistance was also provided by the US colleagues. Furthermore, the partner of the project – the Kirov Center for Ecological Initiatives “Press-Torf (Peat)” – even arranged production of sorbent trial lots.
Sergey Komarov | alfa
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Syntax in Haskell In most imperative programming languages, the assnment statement (or expression) is a fundamental construct. Variable assnment or declaration declaration. a, partial application in the examples below, a normal is "fa,b" give the first argument to operator.
Chapter 1. Getting Started Recent experiences from a few of my fellow C /Java programmers indicate that they read various Haskell tutorials with "exponential speedup" (think about how TCP/IP session starts up). For example, the multiplication operator has a hher precedence than the addition operator, so Haskell treats the following two expressions as.
The Anatomy of the Assnment Operator There is a certain mystique about monads, and even about the word "monad" itself. If you don't want a class to be copied, for example, you have to define an empty copy constructor and assnment operator yourself and make them.
Perlop - org While one of our goals of this set of chapters is removing the shroud of mystery that is often wrapped around them, it is not difficult to understand how it comes about. These combined assnment operators can only operate on scalars, whereas the ordinary assnment operator can assn to arrays, hashes, lists and even.
Obituaries WBRY FM 96.7 AM 1540 I have “pure” functions which work on regular lists and sucike. Suppose I have a “regular” function which does all the complicated, time-consuming process. For the sake of simplicity, suppose the “complicated” processing looks like this: import Data. Lieutenant Commander Robert L. Page was born in Warren Co. TN and passed away Wednesday, November 9, 2016 suddenly in San Diego, CA. were he was on active duty with.
Special members - C++ Tutorials Selection criteria: A programming language enters the history if it has a compiler or an interpreter or if it has inspired other programming languages. - Years 70: Duel between structured programming with Pascal and efficiency of C language. The copy assnment operator is also a special function and is also defined implicitly if a class has no custom copy nor move assnments nor move.
Hitchhikers guide to Haskell - Haskell Known to millions of television viewers as ornery little Charlie Wooster on La grande caravane (1957), he was ornery long before that. This is an example of the Haskell syntax for doing IO namely, input. As you mht have heard, Haskell has no notion of "assnment", "mutable state", "variables", and is a "pure functional language", which. operator.
PHP Assnment Operators - Manual Our early learning of Haskell has two distinct aspects. In addition to the basic assnment operator, there are "combined operators" for all of the arithmetic, array union and string operators that.
History and Evolution of Programming Languages - scriptol Thus, chains of lambdas pass the results downstream. History and Evolution of Programming Languages. Timeline of general-purpose programming languages by Denis Sureau. Selection criteria A programming language enters.
Syntax - What characters are permitted for haskell operators? -. In programming languages, the associativity (or fixity) of an operator is a property that determines how operators of the same precedence are ed in the absence of parentheses. I expect you could use ⊗ as a Haskell operator, but I don't know for sure. compound assnment operators | <urn:uuid:ca6e226f-3cbe-4f52-8928-c3758c1b7fda> | 3.078125 | 720 | Content Listing | Software Dev. | 37.704818 | 95,492,259 |
Why do YOU care about neutrinos? Can neutrinos be used for rockets? more on today’s Space radio at #365daysofastro with @PaulMattSutter.
Author Archive | Paul M. Sutter
What happens close to the speed of light? Can dark matter stars exist? more on today’s Space radio at #365daysofastro with @PaulMattSutter.
What does momentum have to do with rockets? Why are nozzles so dang important?
An interstellar visitor outstays its welcome? How about the space octopus? lets discuss about it.
The black holes are swaaaarming and what is a dwarf galaxy?
Why the universe expands? How can black holes form in the big bang? more with @PaulMattSutter at #365DaysOfAstro
What is the so-called “OMG Particle”? Where could it possibly come from, and how are magnetic fields involved? How can we detect these cosmic rays?
Bezos Uber Alles! Could a black hole kill the galaxy? and lets talk about Hawking’s last paper. | <urn:uuid:cd0231ab-a002-473e-8803-358c10d90e42> | 2.59375 | 238 | Content Listing | Science & Tech. | 62.013333 | 95,492,267 |
Two Canadian astronomers published a study that claims an anomaly in the pulsing of a group of stars is possibly evidence of an alien civilization. It’s easy to be skeptical of any such proposals but the scientists really do consider an extraterrestrial involvement as one of the potential explanations to what they’ve observed.
The scientists Ermanno Borra and Eric Trottier from the Université Laval in Quebec analyzed modulations in 2.5 million stars from the Sloan Digital Sky Survey project and concluded that 234 of them exhibited strange behavior. In fact, the stars seemed to be signaling, with the conceivable explanation that it’s aliens trying to make contact. This theory was bolstered by the conclusion that the 234 signals perfectly matched the shape of an extraterrestrial intelligence (ETI) signal, predicted by Borra’s previous study.
Also working in their favor is the sheer specificity of the sample - 234 stars out of 2.5 million emit a very specific signal, something that fits into previous ETI models.
“We find that the detected signals have exactly the shape of an [extraterrestrial intelligence] signal predicted in the previous publication and are therefore in agreement with this hypothesis,” the scientists write in their paper. “The fact that they are only found in a very small fraction of stars within a narrow spectral range centered near the spectral type of the sun is also in agreement with the ETI hypothesis.”
The scientists do acknowledge that other explanations are possible for the weird signals, like “rotational transitions in molecules” or “rapid pulsations” or maybe even the unusual chemistry of a small group of galactic halo stars.
But you know it’s aliens.
Also thinking that this is worth a closer look is the Breakthrough Listen Initiative, a $100 million program aimed at looking for intelligent life in space. It's headlined by Stephen Hawking and Mark Zuckerberg. The group announced that it will look into the findings of the Canadian astronomers further, but would like to see some independent proof.
In its statement, Breakthrough Listen summarized its goals with respect to the strange signals:
“Extraordinary claims require extraordinary evidence. It is too early to unequivocally attribute these purported signals to the activities of extraterrestrial civilizations.”
“Internationally agreed-upon protocols for searches for evidence of advanced life beyond Earth (SETI) require candidates to be confirmed by independent groups using their own telescopes, and for all natural explanations to be exhausted before invoking extraterrestrial agents as an explanation.”
The study is published in the Solar and Stellar Astrophysics journal.
Here is the announcement of the objectives for the Breakthrough Initiatives by the Russian billionaire Yuri Milner and Stephen Hawking: | <urn:uuid:5b74c7e5-c72a-4779-95c3-ec2b2a9504bb> | 2.78125 | 563 | News Article | Science & Tech. | 27.444431 | 95,492,277 |
Joint press release by the International Institute for Applied Systems Analysis (IIASA) and the Potsdam Institute for Climate Impacts Research (PIK)
Targeting emissions of non-CO2 gases and air pollutants with climate effects might produce smaller benefits for long-term climate change than previously estimated, according to a new integrated study of the potential of air pollution and carbon dioxide mitigation.
High hopes have been placed on limiting emissions of so-called short-lived climate forcers (SLCF) such as methane and soot for protecting human health, vegetation and limiting temperature increase.
These emissions originate from a broad variety of sources, including diesel engines, stoves, cows, and coal mines. They stay in the atmosphere from days to a decade while CO2 lasts thousands of years.
New research indicates that neglecting linkages between the sources of these SLCFs and CO2 has led to an overestimation of the long-term climate benefits of controlling these pollutants in climate stabilization scenarios, according to a new study published in the journal Proceedings of the National Academy of Sciences (PNAS).
“Stabilizing climate at any temperature means that, at some point, global CO2 emissions have to become zero,” says IIASA researcher Joeri Rogelj, who led the study. “Although near-term action on short-lived climate forcers can help reduce warming in the coming decades and also provides other societal benefits, such as cleaner air, it will not buy us time for delaying the reductions in carbon dioxide emissions which are required to stabilize the climate at safe levels.”
“The one and only thing that can avoid the bulk of risks that would come with unbridled climate change is rapid CO2 reduction” says John Schellnhuber, a study co-author and director of the Potsdam Institute for Climate Impact Research. “Hopes that cutting other emissions would do a large part of the job now turn out to be misguided. Our study provides new scientific evidence that decision-makers need to make their choices for CO2 reductions. Note, however, that tackling short-lived pollutants is a reasonable goal in itself.”
Previous studies, including IIASA research, had shown that immediate action to limit SLCFs such as methane and black carbon could significantly reduce premature mortality from air pollution, increase agricultural yields, and help minimize short-term climate warming [http://www.iiasa.ac.at/web/home/research/researchPrograms/SLCF.en.html]. In the new study, the researchers extended the scope of their research to include both the short (decadal) and long term (centennial) perspective and assessed the impacts of air pollutants, methane, hydrofluorocarbons, and CO2 control measures in an integrated framework.
SLCFs and CO2 are often emitted by the same sources, such as diesel cars and coal stoves. The new study quantified to which degree efforts to reduce CO2 emissions also lead to reduced SLCF emissions over time due to the elimination of common emission sources under a wide range of air pollution control assumptions. Limiting SLCFs can impact climate change in the coming decades. However, reducing particulate air pollution such as soot and sulfur dioxide can be achieved without capturing CO2, by cleaning exhaust of cars, industrial boilers, or replacing fuel wood for cooking with clean fuels. So addressing air pollution alone would not necessarily limit CO2 emissions–a necessary condition to reduce long-term temperature rise.
“The new study highlights the critical importance of integrated approaches to problems such as climate change, air pollution, and energy policy,” says Rogelj.
“While urgent action to reduce CO2 emissions is indispensable for the protection of climate, additional SLCF measures would deliver undisputed benefits for human health and agriculture and near-term climate change, even if their contribution to long-term climate targets is less than previously estimated.” says IIASA Mitigation of Air Pollution and Greenhouse Gases Program Director Markus Amann, who also contributed to the study.
IIASA research has also shown that simultaneous and coordinated action on air pollution and climate change could lead to reduced cost than addressing both separately. http://www.iiasa.ac.at/web/scientificUpdate/2013/researchProgram/MitigationofAirPollution/Co-benefits.html
Rogelj, J, Schaeffer M, Meinshausen M, Shindell D, Hare W, Klimont Z, Velders G, Amann M, Schellnhuber HJ. 2014. Disentangling the effects of CO2 and short-lived climate forcer mitigation. Proceedings of the National Academy of Sciences (PNAS). www.pnas.org/cgi/doi/10.1073/pnas.1415631111
For more information contact:
+43(0) 2236 807 393
through the PIK press office
Tel. +49 179 3998862
Mitigation of Air Pollution and Greenhouse Gases
+43(0) 2236 807 432
IIASA Press Office
Tel: +43 2236 807 316
Mob: +43 676 83 807 316
IIASA is an international scientific institute that conducts research into the critical issues of global environmental, economic, technological, and social change that we face in the twenty-first century. Our findings provide valuable options to policy makers to shape the future of our changing world. IIASA is independent and funded by scientific institutions in Africa, the Americas, Asia, Oceania, and Europe. www.iiasa.ac.at
PIK addresses crucial scientific questions in the fields of global change, climate impacts and sustainable development. The institute is a member of the Leibniz Association and receives its core funding from the German federal government and the Federal State of Brandenburg. It was founded in 1992 and has a staff or more than 300. Researchers from the natural and social sciences work together to generate interdisciplinary insights and to provide society with sound information for decision making. The main methodologies are systems and scenarios analysis, modelling, computer simulation, and data integration www.pik-potsdam.de
Katherine Leitzell | idw - Informationsdienst Wissenschaft
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
Drones survey African wildlife
11.07.2018 | Schweizerischer Nationalfonds SNF
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Authors: George Rajna
Now, in a study in Nature Communications, a research team led by Nagoya University has discovered superconductivity in a QC for the first time. University of Groningen physicists, and colleagues from Nijmegen and Hong Kong, have induced superconductivity in a monolayer of tungsten disulfide. One can also imagine making a superconducting transistor out of graphene, which you can switch on and off, from superconducting to insulating. That opens many possibilities for quantum devices." A team of scientists has detected a hidden state of electronic order in a layered material containing lanthanum, barium, copper, and oxygen (LBCO). Now in a new study, researchers have discovered the existence of a positive feedback loop that gratly enhances the superconductivity of cuprates and may shed light on the origins of high-temperature cuprate superconductivity— considered one of the most important open questions in physics. Using ultracold atoms, researchers at Heidelberg University have found an exotic state of matter where the constituent particles pair up when limited to two dimensions. Neutron diffraction at the Australian Centre for Neutron Scattering has clarified the absence of magnetic order and classified the superconductivity of a new next-generation of superconductors in a paper published in Europhysics Letters. A potential new state of matter is being reported in the journal Nature, with research showing that among superconducting materials in high magnetic fields, the phenomenon of electronic symmetry breaking is common. Researchers from the University of Geneva (UNIGE) in Switzerland and the Technical University Munich in Germany have lifted the veil on the electronic characteristics of high-temperature superconductors. Their research, published in Nature Communications, shows that the electronic densities measured in these superconductors are a combination of two separate effects. As a result, they propose a new model that suggests the existence of two coexisting states rather than competing ones postulated for the past thirty years, a small revolution in the world of superconductivity.
Comments: 30 Pages.
[v1] 2018-03-27 05:07:03
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Heidelberg physicists determine equation of state – basis for understanding superconductivity
In a laboratory experiment, physicists at the Center for Quantum Dynamics of Heidelberg University have succeeded in determining the equation of state for an atomic gas, which can be used to precisely describe the thermodynamic properties of this physical system.
Fig.: Puneet Murthy
In a gas of ultracold lithium atoms, identical particles repel each other by the rules of quantum mechanics, while unlike atoms can attract each other and form molecules. Theoretical physicists around Dr. Tilman Enss have now determined the equation of state, i.e., how the attraction changes the density of the quantum gas, from an experiment in the group of Prof. Selim Jochim in Heidelberg.
According to Associate professor Dr. Tilman Enss and Prof. Dr. Selim Jochim, the equation lays the foundation for further experiments using ultracold atoms to better understand the mechanisms of superconductivity, i.e., the lossless conduction of electricity. The results of their research were published in the journal “Physical Review Letters”.
“Everyone knows how air becomes thinner as you climb a mountain. In physics this effect is described by an equation of state, which in this instance determines how the density of air changes in relation to the distance from the Earth,” explains Dr. Enss of the Institute for Theoretical Physics.
“The same principle applies in many areas of physics – from the distribution of matter in the structure of stars to atomic gases, which we were recently able to manufacture in the laboratory,” says Prof. Jochim, a researcher at the Institute for Physics. At the Center for Quantum Dynamics, the researchers have combined Dr. Enss’ theoretical calculations with the findings from Prof. Jochim’s experiments. Their investigation focused on an atomic gas cooled to a temperature near absolute zero.
Physicists find ultracold atomic gases so interesting because the quantum physical effects are clearly evident at extremely low temperatures. In a certain type of particle – the fermion – two atoms can never assume the same state or occupy the same space.
“The fermions exert pressure on similar types of particles and push them aside so that the density in an atomic cloud can never become too great,” explains Prof. Jochim, whose experimental working group observed this effect using lithium atoms. The pressure between the fermions causes the atomic cloud to thin and spread out.
Researchers in theoretical physics have long been interested in how the density of gas changes when fermions also attract. This counteracts the pressure of the fermions and brings the particles closer together.
“If there is sufficient attraction between two fermions, they form a pair. According to the laws of quantum physics, these types of molecules can get closer together than the original fermions. Exactly how this happens in particles that move in a single plane is currently an important question,” explains Dr. Enss. The atomic gases are of great interest for research because they have many universal properties that are found in completely different physical situations. The equation of state of an atomic gas, for example, can be used to draw conclusions about the structure of certain stars.
Ultracold atoms are especially good in experiments for measuring how the equation of state relates to particle attraction. Practically any strength of attraction can be artificially created in ultracold atoms. Prof. Jochim and his research group observed that a strong attraction in the centre of the atomic cloud formed a denser nucleus.
Theoretical physicists Dr. Enss and Dr. Igor Boettcher have now reconstructed the equation of state by analysing the experimental data, thereby confirming their own theoretical predictions. The researchers are particularly interested in atoms that move in one plane.
The atomic gas then exhibits a similarity to layered materials that are superconducting even at a relatively high temperature. According to the Heidelberg researchers, the equation of state determined can now be used as a basis for future experiments to better understand the mechanisms of high-temperature superconductivity.
For their article published in the “Physical Review Letters”, the Heidelberg researchers received the “Editors’ Suggestion” distinction. It also was highlighted in a “Viewpoint” in the magazine “Physics”.
I. Boettcher, L. Bayha, D. Kedar, P. A. Murthy, M. Neidig, M. G. Ries, A. N. Wenz, G. Zürn, S. Jochim, and T. Enss: Equation of state of ultracold fermions in the 2D BEC-BCS crossover region, Physical Review Letters (published online on 27 November 2016), doi: 10.1103/ PhysRevLett.116.045303
Assoc. Prof. Dr. Tilman Enss
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Marietta Fuhrmann-Koch | idw - Informationsdienst Wissenschaft
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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...
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17.07.2018 | Power and Electrical Engineering | <urn:uuid:bd39363a-7b0c-4ce5-b738-6ee3eba57d41> | 3.140625 | 1,727 | Content Listing | Science & Tech. | 38.79024 | 95,492,303 |
A longstanding mystery in biology is how the millions of molecules bumping around in a cell "find" one another and organize into functional structures. So it was a big surprise in 2008 when participants in the Marine Biological Laboratory (MBL) Physiology course realized that simple phase separations - like oil separating from water - may be one important way to create order inside a cell.
While not without controversy, this idea has taken cell biology by storm. In the past decade, scientists have watched protein and RNA molecules condensing into droplets, or membrane-free condensates, in many kinds of cells, from bacterial to human. They have also noted that the same proteins that form liquid droplets in healthy cells can "solidfy" in the context of disease, such as neurodegenerative disorders. But what makes certain molecules come together in the same droplet, while others are excluded, has been unexplained.
In the journal Science, a team shows for the first time that RNA molecules recognize one another to condense into the same droplet due to specific 3D shapes that the molecules assume. The study's senior author and colleagues show that RNA molecules end up in the same droplet if their 3D structures allow them to bind together through complementary base-pairing. The polyQ-protein Whi3 induces conformational changes in RNA structure and generates distinct molecular fluctuations depending on the RNA sequence.
"RNA molecules will end up in different droplets if their secondary (3D) structures are shielding any complementarity. But with the RNAs that condense into the same droplet, their complementary sequences are really exposed, so they can find each other and base pair to make a higher-order interaction," senior author says.
This finding is important in that it reveals a selective mechanism for forming these RNA-protein condensates -- which scientists are seeing everywhere in cells but whose function is still unclear. The condensates may serve as "crucibles" for enhancing biological reactions by concentrating specific molecules together. Or they may sequester molecules that the cell doesn't need for a particular biological process.
Researchers have previously demonstrated in fungus that it's critical that the cell undergo a liquid-liquid phase separation in order for two different biological process to occur. "But we need more examples of where it really matters for cell function," senior author says. The field needs evidence "that this is not just something that proteins and RNAs can do, but that nature has selected for it," author continues.
There are also indications that transition of these liquid condensates to a more solid state may be a factor in protein aggregation diseases, such as Alzheimer's, Parkinson's and Huntington's diseases, ALS, and prion diseases. The current finding, senior author says, "helps us understand how the right components get recruited to droplets so cells can potentially avoid this transition to an aberrant, solid state."
RNA-RNA interactions to form liquid droplets in cells
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A newly published study examines the “habitable zone” that scientists believe might play a role in the survival of extreme life forms, like lichens and bacteria, on exoplanets.
Astronomers have discovered a veritable rogues’ gallery of odd exoplanets — from scorching hot worlds with molten surfaces to frigid ice balls.
And while the hunt continues for the elusive “blue dot” — a planet with roughly the same characteristics as Earth — new research reveals that life might actually be able to survive on some of the many exoplanetary oddballs that exist.
“When we’re talking about a habitable planet, we’re talking about a world where liquid water can exist,” said Stephen Kane, a scientist with the NASA Exoplanet Science Institute at the California Institute of Technology in Pasadena. “A planet needs to be the right distance from its star — not too hot and not too cold.” Determined by the size and heat of the star, this temperature range is commonly referred to as the “habitable zone” around a star.
Kane and fellow Exoplanet Science Institute scientist Dawn Gelino have created a resource called the “Habitable Zone Gallery.” It calculates the size and distance of the habitable zone for each exoplanetary system that has been discovered and shows which exoplanets orbit in this so-called “goldilocks” zone. The Habitable Zone Gallery can be found at www.hzgallery.org. The study describing the research appears in the Astrobiology journal and is available at http://arxiv.org/abs/1205.2429.
But not all exoplanets have Earth-like orbits that remain at a fairly constant distance from their stars. One of the unexpected revelations of planet hunting has been that many planets travel in very oblong, eccentric orbits that vary greatly in distance from their stars.
“Planets like these may spend some, but not all of their time in the habitable zone,” Kane said. “You might have a world that heats up for brief periods in between long, cold winters, or you might have brief spikes of very hot conditions.”
Though planets like these would be very different from Earth, this might not preclude them from being able to support alien life. “Scientists have found microscopic life forms on Earth that can survive all kinds of extreme conditions,” Kane said. “Some organisms can basically drop their metabolism to zero to survive very long-lasting, cold conditions. We know that others can withstand very extreme heat conditions if they have a protective layer of rock or water. There have even been studies performed on Earth-based spores, bacteria and lichens, which show they can survive in both harsh environments on Earth and the extreme conditions of space.”
Kane and Gelino’s research suggests that habitable zone around stars might be larger than once thought, and that planets that might be hostile to human life might be the perfect place for extremophiles, like lichens and bacteria, to survive. “Life evolved on Earth at a very early stage in the planet’s development, under conditions much harsher than they are today,” Kane said.
Kane explained that many life-harboring worlds might not be planets at all, but rather moons of larger, gas-giant planets like Jupiter in our own solar system. “There are lots of giant planets out there, and all of them may have moons, if they are like the giant planets in the solar system,” Kane says. “A moon of a planet that is in or spends time in a habitable zone can be habitable itself.”
As an example, Kane mentioned Titan, the largest moon of Saturn, which, despite its thick atmosphere, is far too distant from the sun and too cold for life as we know it to exist on its surface. “If you moved Titan closer in to the sun, it would have lots of water vapor and very favorable conditions for life.”
Kane is quick to point out that there are limits to what scientists can presently determine about habitability on already-discovered exoplanets. “It’s difficult to really know about a planet when you don’t have any knowledge about its atmosphere,” he said. For example, both Earth and Venus experience an atmospheric “greenhouse effect” — but the runaway effect on Venus makes it the hottest place in the solar system. “Without analogues in our own solar system, it’s difficult to know precisely what a habitable moon or eccentric planet orbit would look like.”
Still, the research suggests that habitability might exist in many forms in the galaxy — not just on planets that look like our own. Kane and Gelino are hard at work determining which already-discovered exoplanets might be candidates for extremophile life or habitable moons. “There are lots of eccentric and gas giant planet discoveries,” Kane says. “We may find some surprises out there as we start to determine exactly what we consider habitable.”
Source: Josh Rodriguez, NASA | <urn:uuid:cf54c923-4e50-412f-ad73-81995c50465c> | 4.28125 | 1,076 | News Article | Science & Tech. | 39.925172 | 95,492,330 |
- Research article
- Open Access
Phylogeny and biogeography of a shallow water fish clade (Teleostei: Blenniiformes)
© Lin and Hastings; licensee BioMed Central Ltd. 2013
Received: 9 July 2013
Accepted: 16 September 2013
Published: 25 September 2013
The Blenniiformes comprises six families, 151 genera and nearly 900 species of small teleost fishes closely associated with coastal benthic habitats. They provide an unparalleled opportunity for studying marine biogeography because they include the globally distributed families Tripterygiidae (triplefin blennies) and Blenniidae (combtooth blennies), the temperate Clinidae (kelp blennies), and three largely Neotropical families (Labrisomidae, Chaenopsidae, and Dactyloscopidae). However, interpretation of these distributional patterns has been hindered by largely unresolved inter-familial relationships and the lack of evidence of monophyly of the Labrisomidae.
We explored the phylogenetic relationships of the Blenniiformes based on one mitochondrial (COI) and four nuclear (TMO-4C4, RAG1, Rhodopsin, and Histone H3) loci for 150 blenniiform species, and representative outgroups (Gobiesocidae, Opistognathidae and Grammatidae). According to the consensus of Bayesian Inference, Maximum Likelihood, and Maximum Parsimony analyses, the monophyly of the Blenniiformes and the Tripterygiidae, Blenniidae, Clinidae, and Dactyloscopidae is supported. The Tripterygiidae is the sister group of all other blennies, and the Blenniidae is the sister group of the remaining blennies. The monophyly of the Labrisomidae is supported with the exclusion of the Cryptotremini and inclusion of Stathmonotus, and we elevate two subgenera of Labrisomus to establish a monophyletic classification within the family. The monophyly of the Chaenopsidae is supported with the exclusion of Stathmonotus (placed in the Stathmonotini) and Neoclinus and Mccoskerichthys (placed in the Neoclinini). The origin of the Blenniiformes was estimated in the present-day IndoPacific region, corresponding to the Tethys Sea approximately 60.3 mya. A largely Neotropical lineage including the Labrisomidae, Chaenopsidae and Dactyloscopidae (node IV) evolved around 37.6 mya when the Neotropics were increasingly separated from the IndoPacific, but well before the closure of the Tethys Sea.
Relationships recovered in this study are similar to those of earlier analyses within the Clinidae and Chaenopsidae, and partially similar within the Blenniidae, but tripterygiid relationships remain poorly resolved. We present the first comprehensive phylogenetic hypothesis for a monophyletic Labrisomidae with five tribes (Labrisomini, Mnierpini, Paraclinini, Stathmonotini and Starksiini). Global distributions of blenny genera included in our analysis support the evolution of a largely Neotropical clade whose closest relatives (clinids and cryptotremines) are temperate in distribution.
The Blenniiformes comprises six families, 151 genera and nearly 900 species of small teleost fishes closely associated with coastal benthic habitats. Although small, blennies often numerically dominate rocky reef ichthyofaunas [2–4]. Because of their abundance and the ease at which they can be observed, blennies have become convenient models for the study of ecology and behavior . Blennies also provide an unparalleled opportunity for marine biogeography because they include the globally distributed families Tripterygiidae and Blenniidae, the temperate Clinidae, and three families (Labrisomidae, Chaenopsidae, and Dactyloscopidae) largely restricted to the Neotropics . The breakup of the Tethys Sea , formation of the Central America Isthmus , and climate warming during the Pliocene have been suggested as important historical events shaping the evolution and current distributional patterns of blennies. However, insights from these and other studies have been compromised by the absence of a well-resolved phylogeny for the group.
The history of blenniiform classification has been reviewed by several researchers (e.g. [1, 10–12]). Members of the currently recognized families Tripterygiidae, Blenniidae, Labrisomidae, Clinidae and Chaenopsidae are consistently included, but other families have been added depending on the definition of “true” blennies [11, 13–16]. A widely accepted concept of a monophyletic Blenniiformes as the “tropical” blenny families (= Blenniicae sensu Hubbs, 1952; ) was revisited by Springer and, based on morphological characters, formalized to include the above five families and the sand stargazers, Dactyloscopidae, as hypothesized earlier by Regan . Springer’s Blennioidei, termed the Blenniiformes by Wiley and Johnson , shares several unique morphological features including presence of a bean-shaped pelvis, a reduced branchial apparatus, proximal pectoral-fin radials longer than wide, unbranched pectoral-fin rays, relatively simple caudal-fin morphology, 0–2 spines and simple segmented rays in the anal-fin, and no neural spine on the first vertebra [11, 18].
Inter-familial relationships of blenniiforms have remained largely unresolved because of conflicting morphological and molecular evidence . It is generally agreed that the Tripterygiidae is the sister group of all other blennies, based on these groups having unbranched dorsal- and pectoral-fin rays (branched in most triplfins), no ctenoid scales as in triplefins, and roofed sensory canal bones (unroofed in triplefins) . It has also been hypothesized that the Blenniidae is the sister group of the remaining blennies based on several features of the dorsal gill-arches and associated muscles . However, a consensus has not been reached regarding relationships among the Clinidae, Chaenopsidae, Dactyloscopidae and Labrisomidae. The monophyly of the first three of these families has been supported by morphological synapomorphies . However, the Labrisomidae includes generalized blennies that do not fall into the other relatively well-defined families and no synapomorphies have been identified for this group other than one possible reductive character . Labrisomids have long been considered to be closely related to the Clinidae (e.g. ) and included in that family by some authors (e.g. ). In addition, the relationships of the Dactyloscopidae to other blennies, the most recent major lineage to be added to the Blenniiformes , have been evaluated based only on dorsal gill-arch anatomy . Thus, dactyloscopids have been placed in an unresolved polytomy along with the Clinidae, Labrisomidae and Chaenopsidae . Two molecular studies have attempted to resolve the phylogenetic relationships among the blenny families [9, 22]. These provided inconsistent phylogenetic hypotheses, although both questioned the monophyly of the Labrisomidae and the Chaenopsidae.
Recently, the systematics of blennies was thoroughly reviewed, providing convenient reference points: the Labrisomidae, Clinidae, Chaenopsidae, and Dactyloscopidae by Hastings and Springer , the Blenniidae by Hastings and Springer and the Tripterygiidae by Fricke . In addition, studies on higher-level relationships of fishes based on morphology and multiple genetic markers have suggested a close relationship between blennies and clingfishes (Gobiesocidae) [19, 25–30], jawfishes (Opistognathidae) [31, 32], and basslets (Grammatidae) [31, 33–35] within the recently recognized Ovalentaria . In the present study, we attempt to reconstruct the phylogenetic relationships of the Blenniiformes with significantly broader taxon sampling (150 blenniiform species), substantially more genetic information (one mitochondrial and four nuclear markers), and more strategic outgroup representation than in previous studies.
Family (total genera/ total species)
Lineage (total genera/ sampled genera)
Genera (total species/ sampled species)
Salariini-Salarias group (20/12)
Salariini-Rhabdoblennius group (8/1)
Proportions of variable and parsimony informative characters, best nucleotide substitution model and parameters selected by jModelTest for each data partition
Parsimony informative characters
Best model by jModelTest
Among the 3,562 bp, the alignment comprised 1,627 (45.68%) variable sites, of which 1,392 (39.08%) were parsimony informative. The sequences of the ten partitions provided a range of evolutionary information. The third codon position of all five markers provided significantly more parsimony information (59.09% to 99.47%) than the first and second positions (4.13% to 28.21%). The third codon of the only mitochondrial marker (COI) had the highest proportion of variable characters (100%) and the highest proportion of parsimony informative characters (99.47%). The first and second codon positions of the nuclear marker Histone H3 had the lowest proportion of both variable characters (9.63%) and parsimony informative characters (4.13%).
In general, the relationships among triplefins were poorly resolved in all analyses (Figure 2). Relationships within the Blenniidae were, however, well resolved, with only a few discrepancies among analytical methods (Figure 3). The monophyly of all blenniid genera for which we sampled multiple species was well supported except that Alticus saliens was nested within Andamia, and Atrosalaris fuscus was nested within Salarias (Figure 3). The monophyly of each the four blenniid tribes included in our study (i.e., Parablenniini, Salariini, Nemophini, and Omobranchini) was well supported with the exception of the Salariini in the MP analysis (MP bootstrap value = 66). The two Blenniinae tribes Nemophini and Omobranchini were grouped together and were the sister group of the tribe Parablenniini. This entire clade was the sister group of the tribe Salariini.
Relationships among the remaining four families were well resolved in the shallower nodes, but less so in the deeper nodes (Figure 4). In general the pattern is the inclusion of low-diversity taxa as the sister group of larger monophyletic clades. These low-diversity groups include Calliclinus (Cryptotremini), Auchenionchus + Alloclinus (both currently Cryptotremini), and the “chaenopsids” Neoclinus and Mccoskerichthys. In addition to a monophyletic Clinidae, all three analytical methods recovered two diverse clades with moderate support values. These included the members of the Labrisomidae (node II) other than the Cryptotremini that together formed a monophyletic group with the inclusion of the genus Stathmonotus (currently considered a chaenopsid). The second lineage (node III) included the Dactyloscopidae plus the Chaenopsidae sensu stricto (i.e., excluding Stathmonotus, Neoclinus and Mccoskerichthys).
Within the labrisomid clade (node II; BI PP=74), BI recovered relationships with Dialommus (Mnierpini) as the sister group of two relatively large clades, the Paraclinini + Stathmonotus, and Starksiini + Labrisomini (Figure 4). Within the Paraclinini, the monotypic genus Exerpes was nested within the genus Paraclinus, while within the Starksiini, the monotypic genus Xenomedea was the sister group of a monophyletic Starksia (Figure 4). Within the Labrisomini, the genus Labrisomus was not monophyletic, but divided into two clades. One clade included the subgenus Labrisomus that was the sister group of the monophyletic genus Malacoctenus, while the other clade included all other sampled members of Labrisomus (Figure 4).
In the remaining large clade (node III; BI PP=86), the monophyletic Dactyloscopidae was the sister group of a monophyletic Chaenopsidae sensu stricto (i.e., exclusive of Stathmonotus, Neoclinus and Mccoskerichthys). Within the Chaenopsidae all currently recognized genera were recovered as monophyletic, and the genus Coralliozetus was the sister group of all other chaenopsids. That group included two large clades, one with Emblemariopsis, Protemblemaria and Cirriemblemaria, and another with Acanthemblemaria, Ekemblemaria, Hemiemblemaria, Emblemaria, Chaenopsis and Lucayablennius (Figure 4).
The divergence times of blenniiform lineages were estimated from the combined postburn-in trees and parameter values of the BEAST analyses (Additional file 2: Figure S1). The maximum clade credibility tree estimated from the posterior density was characterized by a large number of nodes supported with significant Bayesian posterior probabilities (data not shown) and the mean of the posterior density of the likelihood score was −78678.5184 (95% highest posterior densities [HPD]: -78748.29 to −78607.9508).
Families and inter-family relationships of the Blenniiformes
Although the monophyly of the Blenniiformes sensu Wiley and Johnson, 2009 (= Blennioidei sensu Springer, 1993; ) has been questioned by some (e.g. ), our phylogenetic analysis found strong support for its monophyly in agreement with other recent molecular analyses (e.g. [32, 35]). Blenniiform monophyly is also supported by seven morphological character complexes [1, 11, 18]. This lineage includes nearly 900 species allocated among six families and is the sister group of the Gobiesocidae (Figure 1), a relationship supported by six morphological characters, one of which is unique to this lineage .
Our study supports the monophyly of four of the six blenniiform families as currently construed. The mono-phyly of the Tripterygiidae, Blenniidae, Clinidae and Dactyloscopidae are also well-supported by morphological synapomorphies [1, 11, 23]. The monophyly of the Chaenopsidae (sensu Hastings and Springer, 1994 ) and the Labrisomidae are, however, not supported in our analysis (see below).
Within the Blenniiformes, our study indicates that the Tripterygiidae is the sister group to the remaining blennies (Figure 1). This hypothesis was proposed by Springer based on details of the fin rays, scales and cephalic sensory system, and subsequently supported by Springer and Orrell based on details of the branchial musculature. Our analysis also supports the hypothesis of Springer and Orrell based on several features of the dorsal gill-arches and associated muscles that the Blenniidae is the sister group of the remaining four families of blennies (Figure 1). That clade includes the Clinidae, Labrisomidae, Chaenopsidae and Dactylosco-pidae and is referred herein as the “clinioids” (node I; Figures 1 and 4). Relationships within the clinioids are complicated and not entirely consistent with the current nomenclature, as reported by earlier studies based on morphological characters , allozyme data , and mitochondrial 12S rRNA sequence data . In our analysis, a single species of the labrisomid tribe Cryptotremini (Calliclinus geniguttatus) is the sister group of all other clinioids, and the monophyletic family Clinidae is the sister group of the remaining clinioids (Figure 4). Our analysis provided partial resolution of deep relationships within the latter lineage, but with short branch lengths to their most recent common ancestors (Figure 4), implying frequent divergence events (Additional file 2: Figure S1) consistent with a rapid radiation . Bayesian Inference and Maximum Likelihood analyses support another two cryptotremins (Alloclinus holderi + Auchenionchus microcirrhis) as the sister group of the remaining species, and two “chaenopsids” (Neoclinus blanchardi + Mccoskerichthys sandae) as the sister group of all others (unresolved in ML) (Figure 4). These low diversity branches are followed by two speciose lineages (node IV), one that includes most labrisomid species (node II; Figure 4), and a second, newly identified clade that includes the Chaenopsidae sensu stricto and the Dactyloscopidae (node III; Figure 4).
The Tripterygiidae, comprising 32 genera and 164 species, can be readily distinguished from other blenniiforms by their three-part dorsal fin which lacks the “last” dorsal-fin spine [11, 24]. Two subfamilies and eight tribes of triplefins have recently been proposed based on morphological evidence [24, 39], but their relationships remain unclear. Recent molecular studies on the phylogenetic relationships of triplefins are restricted to regional studies with limited taxon sampling (e.g. [40–42]) and the same is partially true of our study. We included representatives of four tribes, eight genera and 19 species from the subfamily Tripterygiinae (Table 1 and Additional file 1: Table S1) with an emphasis on eastern Pacific species. Although the monophyly of triplefins is strongly supported by our data, there is a general pattern of low node support values within the family (Figure 2). Our poor resolution of relationships within the Tripterygiidae is likely a consequence of inadequate taxon sampling (19 of 164 species), incomplete data sampling (i.e. missing data for some markers), the presence of numerous insertions and deletions observed in the sequences of TMO-4C4 and RAG1 which complicates phylogenetic analyses , and the possible rapid diversification of the group . Clearly much broader taxon sampling and further study will be needed to resolve relationships within the triplefins.
We sampled 20 genera and 48 species, representing four of the six tribes and both subfamilies Blenniinae and Salariinae (Table 1 and Additional file 1: Table S1). Two low diversity tribes, the Blenniini with four species and the monotypic Phenablenniini, were not included in our analysis. The monophyly of the four tribes included in our study is supported (Figure 3), as is the monophyly of the Blenniinae. However, the monophyly of the Salariinae (sensu Bath, 2001 ) is not supported. Instead, we found the Parablenniini to be the sister group of the Blenniinae rather than the Salariini (Figure 6b). However, because our study included few genera of the Parablenniini (2 of 14) and did not include a member of the tribe Blenniini, additional taxon sampling is necessary to more fully resolve the relationships of the major lineages of blenniids.
The Nemophini genera Meiacanthus, Plagiotremus, Petroscirtus, and Xiphasia form a monophyletic clade that is sister to the Omobranchini genus Omobranchus (Figure 3). Within the Nemophini, this analysis provides an alternative phylogeny to the provisional hypothesis proposed by Smith-Vaniz in which Meicanthus and Petroscirtes together were the sister group of Plagiotremus, Xiphasia, and Aspidontis. In our analysis, Meiacanthus and Plagiotremus form a strongly supported clade that is the sister group of Petroscirtus and Xiphasia (Figure 3). Relationships of the three species of Plagiotremus included in our study are consistent with those proposed by Smith-Vaniz (, Fig 81).
Only two out of the fourteen Parablenniini genera (Hypsoblennius and Parablennius) are included in our study and these form a monophyletic group (Figure 3). The six Hypsoblennius species show incongruent relationships from those suggested by Bath in several respects.
The monophyly of the Clinidae, comprising 26 genera and 85 species, is supported by the presence of cycloid scales with radii in all fields and a cordlike ligament extending from the ceratohyal to the dentary [11, 14, 53]. Three tribes are recognized within this family [14, 53] and a hypothesized relationship of the Myxodini as the sister group of the Clinini + Ophiclinini is based on the latter two sharing the reproductive pattern of internal fertilization with males possessing an intromittent organ . Our study includes representatives of the Clinini and Myxodini and the monophyly of each is well supported (Figure 4). Species relationships within the Myxodini genus Gibbonsia (Figure 4) are congruent with the previously hypothesized relationships based on 40 allozyme loci , but conflict with a more recent study with expanded taxon sampling based on the same allozyme loci and 12S rRNA data . Within the Clinini, the Australian genera Heteroclinus and Cristiceps form a well-supported sister group to the South African genera Clinus, Muraenoclinus, Blennophis, and Pavoclinus (Figure 4).
The monophyly of the Labrisomidae has long been questioned because of the lack of any supporting morphological characters [11, 19] or molecular evidence [9, 22]. Also, relationships among the five included tribes remain unclear . Our study includes representatives of all five hypothesized tribes and 10 of the 14 genera (Table 1 and Additional file 1: Table S1). The only genera not included are the Eastern Pacific deepwater (> 20 m depth) genus Cryptotrema with two species (Cryptotremini; [14, 55]), the recently described monotypic Cottoclinus (Mnierpini; ), and two rare and poorly known genera of uncertain relationships, Nemaclinus with one species and Haptoclinus with two species [21, 58]. The present study thus provides the most thorough investigation to date of the phylogenetic relationships of members of this family.
In our analysis, a monophyletic Labrisomidae (node II; Figure 4) is recovered with the exclusion of the Crypto-tremini and the inclusion of Stathmonotus. In our BI analysis, Stathmonotus is the sister group of the Para-clinini, and that clade is the sister group of a clade including the Starksiini and Labrisomini (Figure 4). However, relationships among the major lineages of labrisomids have strong nodal support only from the BI analysis.
The tribe Cryptotremini is the only exclusively temperate group historically allocated to the Labrisomidae while all others are primarily tropical. This tribe was first described by Hubbs who included the northeastern Pacific genera Alloclinus and Cryptotrema. The Cryptotremini was later expanded with the addition of two southeastern Pacific genera (Auchenionchus and Calliclinus), although their inclusion was based on the plesiomorphic condition of branched caudal-fin rays . The caudal-fin rays are unbranched in all other labrisomids but branched in the Tripterygiidae, most Blenniidae and some Dactyloscopi-dae. None of the analytical methods used in our study support the monophyly of the Cryptotremini (Figure 4). Instead the genus Calliclinus is the sister group of all other clinioids, the northern genus Alloclinus is grouped with the southern genus Auchenionchus, and that clade is the sister group of the clinioids exclusive of the Clinidae and Calliclinus. While support values for many of these relationships are not strong, the evolutionary position of cryptotremins as early branching lineages of a diverse clade including the labrisomids was also suggested by morphological and allozyme data . Additional study of cryptotremin blennies should provide a clearer picture of clinioid relationships.
Species allocated to three genera previously placed in the genus Labrisomus
Labrisomus Swainson, 1837
Labrisomus conditus Sazima, Carvalho-Filho, Gasparini and Sazima, 2009 a
Labrisomus cricota Sazima, Gasparini and Moura, 2002 a
Labrisomus fernandezianus (Guichenot, 1848)#
Labrisomus jenkinsi (Heller and Snodgrass, 1903)
Labrisomus multiporosus Hubbs, 1953
Labrisomus nuchipinnis (Quoy and Gaimard 1824)*+
Labrisomus philippii (Steindachner, 1866)
Labrisomus pomaspilus Springer and Rosenblatt, 1965 a
Labrisomus socorroensis Hubbs, 1953
Labrisomus wigginsi Hubbs, 1953
Labrisomus xanti Gill, 1860 +
Brockius Hubbs, 1953
Brockius albigenys (Beebe and Tee-Van, 1928)
Brockius nigricinctus (Howell Rivero, 1936) +
Brockius striatus (Hubbs, 1953)* +
Gobioclinus Gill, 1860
Gobioclinus bucciferus (Poey, 1868) +
Gobioclinus dendriticus (Reid, 1935)
Gobioclinus filamentosus (Springer, 1960)
Gobioclinus gobio (Valenciennes 1836)*
Gobioclinus guppyi (Norman, 1922) +
Gobioclinus haitiensis (Beebe and Tee-Van, 1928) +
Gobioclinus kalisherae (Jordan, 1904)
Ten of the twenty-one Malacoctenus species are included in our study and these form a well-supported clade that is the sister group of Labrisomus sensu stricto (Figure 4). Our study recovered one well-supported lineage within Malacoctenus comprising five Eastern Pacific species. However, greater taxon sampling, especially of Caribbean species, is needed to resolve the relationships within this speciose genus.
The monophyly of the tribe Starksiini, including Starksia and Xenomedea, is supported in our analysis (Figure 4). Members of this lineage reportedly share internal fertilization and a modification of the first anal-fin spine that functions as an intromittent organ in males [14, 63]. However, a recent study indicates that reproductive modes vary within this lineage and not all Starksia species exhibit internal fertilization .
The two genera currently included in the tribe Paraclinini, Paraclinus and Exerpes, share the unique characters of a spine on the posterior margin of the opercle and 0–2 segmented dorsal-fin rays [14, 65, 66]. Results from our study support the monophyly of the tribe (Figure 4), although the monotypic genus Exerpes is nested within Paraclinus, rendering the genus Paraclinus paraphyletic. Exerpes asper can be distinguished from members of the genus Paraclinus in having greatly prolonged snout, no cirri on the nape or eye, scales in the anterior segment of the lateral line consisting of a pore at each end of a tube, and by the absence of the suborbital lateral-line canal . However, this species shares several features such as an elongate snout with selected Paraclinus species, especially Paraclinus infrons. Additional study of relationships within this lineage are needed, but based on our findings and those of Brooks , we synonomize the genus Exerpes Jordan and Evermann, 1896 with Paraclinus Mocquard, 1888.
The phylogenetic relationships of the seven species of small (< 55 mm SL), cryptic, eel-like blennioids of the genus Stathmonotus have been controversial for many years . Jordan considered Stathmonotus to be closely related to chaenopsids based on both groups lacking scales. However, Springer included the scaled species Auchenistius stahli in Stathmonotus, and suggested that their affinities were with Paraclinus, not chaenopsids. Consequently, Stathmonotus was included in the generalized blenniiform family Labrisomidae [68, 69]. Based on six morphological synapomorphies, Hastings and Springer placed Stathmonotus back in the Chaenopsidae as the sister group of the Chaenopsinae (= Chaenopsidae of Stephens, 1963; ). The present study based on molecular data confirms the distinctiveness of Stathmonotus, but the BI analysis supports its relationship as the sister group of the Paraclinini (Figure 4). Stathmonotus is similar to Paraclinus in post-cranial morphology, especially in having the dorsal fin comprised entirely (or mostly in the case of some Paraclinus species) of robust spines. However, it is similar to chaenopsids in cranial morphology and parsimony analysis of morphological characters places Stathmonotus with the chaenopsids because more characters are evident within the cranial region . These observations, with different suites of characters shared with disparate lineages, are consistent with a hybrid origin for this enigmatic taxon , but this hypothesis remains speculative, requiring further study. Given its morphological distinctiveness , we recommend recognizing the tribe Stathmonotini within the Labrisomidae.
Stephens hypothesized the close relationship of the temperate hole-dwelling genus Neoclinus with the tropical chaenopsid blennies. This relationship was given further credence by the discovery of the tropical species Mccoskerichthys sandae that resembles Neoclinus, but also shares several morphological features (e.g., medially fused nasal bones) with chaenopsids . The recent placement of Neoclinus and Mccoskerichthys in the lineage with the chaenopsids based on a parsimony analysis of morphological features is not supported in our study and implies significant morphological convergence associated with the hole-dwelling lifestyles of these fishes. The sister-group relationship between Neoclinus and Mccoskerichthys is well supported in our study, thus we recommend their designation as the Neocliniini. However, their placement as the sister group of the clinioids exclusive of the Cryptotremini and Clinidae (Figure 4) is only weakly supported by Bayesian Inference. Further study is required to determine their position within the Blenniiformes.
In our analysis, the Chaenopsidae is monophyletic with the exclusion of Stathmonotus, Neoclinus and Mccoskerichthys, three genera allocated to this group by Hastings and Springer . This result resurrects the definition of the Chaenopsidae sensu Stephens [70, 73]. This clade is well-supported by morphological features and relationships within it were recently analyzed by Lin and Hastings using a combination of molecular and morphological characters. Results from the present analysis that included a much broader selection of outgroup taxa but fewer ingroup species, are largely congruent with those of Lin and Hastings except for species relationships within Acanthemblemaria, a group recently studied in greater detail .
The dactyloscopids, also known as sand stargazers, are a distinctive group with several known morphological syanpomorphies, many of which are associated with their sand or gravel dwelling behaviors [1, 11, 36]. In our study, only four out of the 48 dactyloscopid species were included and they formed a well-supported monophyletic group based on our molecular data (Figure 4).
Unresolved issues in blenniiform relationships
While our analysis clarifies several aspects of the relationships of the Blenniiformes, several significant questions remain. Relationships within the Tripterygiidae are not well understood and our study, with limited taxon sampling, contributes little to this issue. Inclusion of taxa from the southern Pacific Ocean, especially from New Zealand and southern Australia where this group is especially diverse [24, 39–42], is needed to resolve relationships within the triplefins. Within the Blenniidae, the relationships of the low diversity, but morphologically distinctive, tribes Blenniini and Phenablenniini need further study. Also, the monophyly of the Parablenniini has not been confirmed although its reality and its relationships to other blenniids may have significant bearing on relationships within the combtooth blennies . Several significant questions remain regarding relationships among the lineages here termed the clinioids (node I; Figures 1 and 4). Chief among these is the relationships of the species currently allocated to the Cryptotremini. This low diversity group of relatively generalized blennies is apparently not monophyletic and in our analysis, its members are variously placed as the sister group of speciose clades of blennies. Morphological convergence in lifestyle and associated morphological features appear to have confounded past morphologically-based analyses of blenny relationships, especially among the tube-dwelling lineages. Also, relationships of the enigmatic worm blennies, genus Stathmonotus, remain unclear as they have for decades. This study supports other recent studies [32, 37] in hypothesizing a sister-group relationship of the Dactyloscopidae and Chaenopsidae (node III; Figure 4). Preliminary study indicates possible morphological features uniting these two (PAH, personal observations), but characterization of this clade may have been confounded by the inclusion of the apparently unrelated fishes of the genera Neoclinus, Mccoskerichthys and Stathmonotus within the Chaenopsidae. Finally, our understanding of species level-relationships within most lineages included herein suffers from poor taxon sampling. Thus relationships recovered in our analyses within speciose genera for which we had few representative species should be considered tentative.
Because of these and other significant issues, we are reluctant to recommend major changes to the higher-level nomenclature of the Blenniiformes at this time. While progress has been made, these and other remaining challenges in resolving blenniiform relationships will require incorporation of additional molecular markers for these and additional taxa, and importantly inclusion of morphological features in a total evidence analysis.
Biogeography of the Blenniiformes
Our mean estimated divergence time for the Blenniiformes, 60.3 mya (Additional file 2: Figure S1), is similar to recent estimates from other studies of ray-finned fishes that place the origin of the Blenniiformes at around 60 to 68 mya . Our study also implies the origin of a largely Neotropical clade of over 240 species (node IV) of the Labrisomidae, Chaenopsidae and Dactyloscopidae at approximately 37.6 mya, somewhat more recent than other estimates of 40 mya and 48 mya for the same clade.
The majority of species in the families Blenniidae and Tripterygiidae occur in the tropical IndoPacific with various other lineages of these families found in the Neotropics and temperate waters of the world [6, 77, 78]. Our analysis implies an origin of the Blenniiformes in the present-day IndoPacific region (Figure 5, Additional file 3: Figure S2), consequently in the Tethys Sea at approximately 60 mya. The origin of the largely Neotropical clade including the Labrisomidae, Chaenopsidae and Dactyloscopidae (node IV) at approximately 37.6 mya is coincident with the increasing opening of the Atlantic Ocean and separation of the New World and Old World land masses, but well before the closing of the Tethys Sea corridor at 12–18 mya [79, 80]. This result supports the findings of Bellwood and Wainwright that the east and west Tethyan reef-fish faunas had diverged well before the terminal Tethyan event.
Interestingly, the intervening blenniiform clades between the primarily east and west Tethyan groups are almost exclusively temperate in distribution (Figure 5, Additional file 3: Figure S2). This finding implies either an evolutionary pathway across temperate coastal areas between increasingly separate east and west tropical regions of the Tethys Sea, or more likely, the subsequent restriction of the intervening clades to temperate refugia . These groups include low-diversity lineages currently included in the paraphyletic Cryptotremini (e.g., Calliclinus, Auchenionchus, Alloclinus and Cryptotrema) and the genus Neoclinus[6, 61], as well as the relatively speciose Clinidae, with 85 species, that has undergone significant diversification within distant temperate regions of the world . The occurrence of these related clades in both northern and southern temperate regions indicates that they have successfully crossed intervening tropical regions during their evolutionary history [82, 83]. Better resolution of relationships and timing of divergence of these largely temperate lineages [6, 77, 78] is an important key to reconstructing the biogeographic history of the Blenniiformes in greater detail.
Other Neotropical lineages of blenniiforms include the salariin blenniid genera Ophioblennius and Scartichthys (the latter not included in our study), part or parts of the Parablenniini [48, 84], and one or more lineages within the Tripterygiidae [6, 24], as well as the Gobiesocini within the sistergroup of blenniiforms, the Gobiesocidae . A more fully resolved phylogeny of these groups with increased taxon sampling is needed to determine which, if any, of these lineages may have diverged coincident with the Neotropical blenniiforms (node IV). A few species of blennies from other primarily IndoPacific clades have invaded the Neotropics including species of the salariin genus Entomacrodus and a single species of the nemophin blenniid genus Plagiotremus. These species are well-nested within IndoPacific clades (Figure 5), supporting the hypotheses that they dispersed to the Neotropics after the origin of their respective genera in the IndoPacific region . Similarly, the few species of primarily Neotropical clades occuring in the eastern Atlantic (e.g., species of the labrisomid genera Labrisomus and Malacoctenus; [6, 87]), and members of the temperate genus Neoclinus in the northwestern Pacific , likely represent relatively recent dispersal events from their regions of origin.
In this study we reconstruct the phylogeny of the Blenniiformes with significantly broader taxon sampling (150 blenniiform species), substantially more genetic information (one mitochondrial and four nuclear markers), and more strategic outgroup representation (Gobiesocidae, Opistognathidae, and Grammatidae) than in previous studies. Progress has been made in resolving the blenniiform evolutionary relationships especially at the inter-familial level and within the Labrisomidae. Several nomenclatural changes are proposed especially in the “clinioid” clade. Examination of global distributions of blenny genera included in our analysis and estimation of divergence times imply an origin of the Blenniiformes in the present-day IndoPacific region, consequently in the Tethys Sea around 60 million years ago. A large and diverse Neotropical clade (node IV, Figures 1, 4, and 5) arose around 37.6 million years ago with intervening lineages largely restricted to temperate regions.
Molecular data for 158 terminal taxa were collected. Additional file 1: Table S1 details the included species, collection localities and deposition of voucher specimens. Our taxon sampling included representatives of all six blenniiform families (Table 1): Tripterygiidae (18 species), Blenniidae (48), Labrisomidae (36), Chaenopsidae (30), Clinidae (14), and Dactyloscopidae (4), as well as the outgroups Gobiesocidae (6), Opistognathidae (1), and Grammatidae (1). Currently recognized lineages within the blenniiform families were sampled with representative species where available (Table 1). Tissue samples were from the Marine Vertebrate Collection at Scripps Institution of Oceanography (SIO), the University of Kansas Natural History Museum (KU), the Biodiversity Research Museum at Academia Sinica (ASIZP), Taiwan and the Australian Museum (AM).
DNA extraction, amplification and sequencing
Total genomic DNA was extracted from muscle tissue with a Qiagen (Chatsworth, CA) QIAquick Tissue Kit following the manufacturer’s instructions. DNA sequences of one mitochondrial DNA marker, Cytochrome C Oxidase I (COI), and four nuclear markers, TMO-4C4, RAG1, Rhodopsin and Histone H3, were obtained. In addition to the primers used in a recent publication on chaenopsid phylogeny , six new primers were designed for amplifying PCR products across this broad sample of taxa: two extended inside primers from TMO-F3 and TMO-R3 for TMO-4C4, TMO-F4 5′-GGTGAAGTGGTTCTGCAACA-3′ and TMO-R4 5′-GCYGTGTACTCNGGRATRGT-3′; two gobiesocid-specific inside primers for RAG1, Rag-GoF 5′-TTCCTCGATCATTTAGTTTCCA-3′ and Rag-GoR 5′-GAAGGGCTTGGAGGAAACTC-3′; two blenniiform-specific inside primers for Rhodopsin, Rhod-BleF 5′-CGTCACCCTCGAACACAAGAA-3′ and Rhod-BleR 5′-GTTGTAGATGGAGGAACTCTT-3′. The PCR was performed on a Mastercycler EP Gradient S (Eppendorf, Hamburg, Germany) with the following conditions: 94°C for one minute for initial denaturing, 35 cycles of 94°C for 30 sec, 52-56°C for 45 seconds, and 72°C for 45 sec, followed by 72°C for 5 minutes as the final extension. Resulting amplicons were purified with Exonuclease I (20 U/μl, New England Biolabs) and Shrimp Alkaline Phosphatase (1 U/μl, Roche) in order to remove single-stranded DNA and unincorporated dNTPs. Sequencing was done in both directions with the amplification primers and DYEnamicTM ET dye terminator sequencing kit on an automated MegaBACE™ 500 DNA sequencer (Amersham Biosciences Corp., Piscataway, NJ).
DNA sequence alignment, partition, and analysis
Sequences were assembled, edited, and aligned with no gaps interrupting reading frames based on translated protein sequences in Geneious . Nucleotide sequences were checked on the NCBI database (http://www.ncbi.nlm.nih.gov/) for possible stop codons as an indication of pseudogenes. Because all five genetic markers are protein-coding genes, the rapidly evolving third codon positions were partitioned from the slower evolving first and second positions in Bayesian and likelihood analyses, resulting in ten total partitions . To avoid base frequency deviations across taxa which can potentially mislead phylogenetic reconstruction , the chi-square test of base frequency homogeneity across taxa was executed for each partition using PAUP 4.0b10 . The Akaike Information Criterion (AIC) implemented in jModelTest v0.1.1 [94, 95] was used to select the best-fit evolutionary model for each partition (Table 2). Likelihood calculations were carried out for 88 models, including 11 substitution schemes, equal or unequal base frequencies, a proportion of invariant sites (I), and rate variation among sites with four rate categories (G) on a BIONJ-JC fixed tree.
Maximum likelihood (ML), Bayesian inference (BI), and maximum parsimony (MP) analyses were conducted to reconstruct the phylogenetic relationships. Maximum likelihood tree searching was conducted in Garli 2.0 under the CIPRES Science Portal v2.2 . Best-fit evolutionary models selected by jModeltest were applied to the ten genetic partitions (five genes for first + second and third codon positions) (Table 2). If a selected model could not be implemented in Garli, the least complex model that included all of the parameters of the selected model was used instead. Therefore, the General Time Reversible model with gamma rate heterogeneity model (GTR+G) was selected for the third codon position of COI, and the GTR+I+G model was selected for all other partitions. Twelve replicates were run to find the tree topology with the best likelihood. The setting of 1,000 replicate bootstrap analysis was identical to the above, except the number of generations without topology improvement required for termination (genthreshfortopoterm) was reduced from 20,000 (default) to 10,000 to reduce the running time as suggested in the manual .
Bayesian Metropolis coupled Markov chain Monte Carlo (MCMC) estimation of the phylogeny was carried out using MrBayes v3.1.2 under the CIPRES Science Portal. The dataset was partitioned and assigned evolutionary models as in the ML analyses. A partitioned mixed-model analysis was applied and all model parameter values were “unlinked” among partitions . In all analyses, the average substitution rates (prset ratepr = variable) and model parameters including the branch lengths within the tree (unlink brlens) were allowed to vary among partitions. Two simulated independent runs were performed for 10 million generations each and starting from different random trees. Each run comprised four chains (one cold and three heated) and was sampled every 1,000 generations. The sampled parameter values from Bayesian MCMC were evaluated in Tracer v1.4 (http://beast.bio.ed.ac.uk/Tracer) and the generations before reaching a plateau were discarded as burnin. Trees from the stationary phase of the two runs were then pooled by LogCombiner v1.5.4 and the 50% majority tree was exported by Mesquite v2.73 . Assigning this tree as the target tree, the posterior probability of each node and the mean branch lengths were calculated with TreeAnnotator v1.5.4 .
Maximum parsimony analyses were conducted using PAUP 4.0b10. Heuristic searches were performed using tree bisection reconnection (TBR) with branch-swapping from 1,000 random-addition-sequence replicates to avoid entrapment in local optima. All nucleotide sites were equally weighted and gaps were treated as missing characters. Nonparametric node supports for trees were estimated with 1,000 heuristic searches (maxTree = 500) starting with 10 random addition sequence replicates.
Divergence times of the blenniiform lineages sampled in our study were estimated with a relaxed molecular clock analysis . Relative divergence times of nodes were estimated in BEAST v1.7.2 assuming an uncorrelated lognormal model (UCLN) of rate variation among branches in the tree and a Yule-process-speciation prior of the branching rate [101, 103]. As in the maximum likelihood and Bayesian analysis described before, the same ten data partitions and molecular evolutionary models were applied to estimate the posterior density of relative divergence times. With TreeEdit v1.0a10 (http://tree.bio.ed.ac.uk/software/treeedit/), the best ML tree from Garli was converted to an ultrametric tree assuming the origin of the Blenniidae as 41 million years old as estimated from a bony fish phylogeny including 21 molecular markers and 1410 fish taxa and assigned as the starting tree. We did not incorporate the putative blenniid fossil from the Monte Bolca formation (50 mya; ), because its identity as a blenniid is in doubt ([11, 105], Springer, pers. comm). Three independent MCMC analyses were each run for 40 million generations, sampled every 1000 generations, and discarding the first 10% of samples, resulting in acceptable mixing as determined by Tracer. These three runs were combined to obtain an estimate of the posterior distribution. The posterior probability density of the combined tree and log files was summarized on a maximum clade credibility tree with TreeAnnotator.
The general distributions of blenniiform genera with representatives included in our analysis were scored as either tropical IndoPacific (I), Neotropical (N), or temperate (T; Additional file 4: Table S2). Genera with species present in more than one of these were scored as polymorphic except where phylogenetic evidence implies recent dispersal into another region after the origin of the genus. For example, Plagiotremus (Blenniidae) was scored as IndoPacific because the single Neotropical species (P. azaleus) is nested within an otherwise entirely IndoPacific clade ([6, 47]; Figure 3).
We used both parsimony implemented in Mesquite and Bayesian Binary MCMC (BBM) methods implemented in Reconstruct Ancestral States in Phylogenetics v2.1 beta (RASP; ) to reconstruct geographical areas at nodes in the phylogeny. The genus–level topology of the best ML tree was used for the reconstruction. The BBM analysis was conducted with estimated character state frequencies (F81) and gamma-distributed rate variation between sites. The root distribution was set to null (i.e. the outgroup is assigned to a new area where none of the ingroup taxa occur). Two independent runs of 10 chains with a temperature of 0.1 were run for one million generations, sampled every 100 generations, and the first 2,500 samples were discarded. A distance between runs of less than 0.01 was used as an indication of convergence.
We thank N. Knowlton for providing laboratory space and equipment, G. Rouse for assisting with data analyses and providing critical comments, R. Burton for insightful comments on molecular methods and the sequencing machine, HJ Walker for curatorial assistance, and R. Rosenblatt and C. Wills for providing valuable comments. Tissue samples were generously provided by the Marine Vertebrate Collection at Scripps Institution of Oceanography, University of Kansas Natural History Museum, Biodiversity Research Museum at Academia Sinica, Taiwan and the Australian Museum. This work was supported by the Study-abroad Scholarship from the Ministry of Education, Taiwan, SIO Rosenblatt Fellowship, the E. B. Scripps Foundation, a gift from B. Shor, the UCSD Academic Senate and a dissertation improvement grant from UC MEXUS.
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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. | <urn:uuid:e8276126-9d22-47b9-8bc7-c4b9b9be9fc2> | 2.578125 | 17,377 | Academic Writing | Science & Tech. | 37.01643 | 95,492,343 |
Gases and Spectra
The model of the atom that is useful in spectroscopy is that in which it is subdivided into three pricipal subatomic particles: proton, neutrom and electron. The multiplicity of other subatomic particles that have been discovered by physicists are important for the under-standing of cosmology and of atomic physics, but their consideration is not necessary for the understanding of the formation of spectra. The two properties of the three principal particles that we need to consider are their mass and their electric charge, as shown in Table 2.1.
KeywordsSpectral Line Metastable State Continuous Spectrum Energy Level Diagram Will Emit
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May 04, 2017 10:38 AM EDT
People have few chances this year to catch some cosmic entertainment. Skywatchers in the Northern Hemisphere already got a view of the Lyrid meteor shower at the end of April. Nonetheless, the Eta Aquarid meteor shower will make its appearance at the first weekend in May.
The Eta Aquarid meteor shower makes its appearance to start at the first weekend in May. If a person is somewhere where the skies are clear during the early morning hours, that person may be able to observe a few meteors. Bill Cooke of NASA's Meteoroid Environment Office stated that there will be up to 30 visible meteors an hour. The Eta Aquarid meteors are one of two meteor showers created by Comet Halley's debris, Space reported.
The Eta Aquarid meteor shower happens between April 22 and May 20. The peak of the Eta Aquarid meteor shower should happen before dawn on May 6.
The Northern Hemisphere people should look toward the southern horizon, while individuals in the Southern Hemisphere should direct one's gaze toward the north. People living near the equator will get the best views of the Eta Aquarid meteor shower, Fox 8 reported.
Although the Eta Aquarid meteors come into sight to originate from the same point, people should not look straight at the radiant to find meteors. If a person does, the person might not witness the meteors that generate the longest bright streaks across the sky. The best way to see the meteors is to lie flat and look straight up. Thus, a person will get the widest view of the sky.
Nevertheless, Eta Aquarid meteor shower appears when Earth passes through the orbital path of Halley's Comet, which means Earth passes through the comet's debris. The debris breaks into Earth's atmosphere and sets up the meteor shower. Meanwhile, the complete revolution of Halley's Comet around the sun takes around 76 years.
Watch The Video Here:
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Eulerian and Hamiltonian circuits are defined with some simple examples and a couple of puzzles to illustrate Hamiltonian circuits.
A serious but easily readable discussion of proof in mathematics with some amusing stories and some interesting examples.
In this third of five articles we prove that whatever whole number we start with for the Happy Number sequence we will always end up with some set of numbers being repeated over and over again.
Show that for natural numbers x and y if x/y > 1 then x/y>(x+1)/(y+1}>1. Hence prove that the product for i=1 to n of [(2i)/(2i-1)] tends to infinity as n tends to infinity.
When is it impossible to make number sandwiches?
A connected graph is a graph in which we can get from any vertex to any other by travelling along the edges. A tree is a connected graph with no closed circuits (or loops. Prove that every tree has. . . .
This article extends the discussions in "Whole number dynamics I". Continuing the proof that, for all starting points, the Happy Number sequence goes into a loop or homes in on a fixed point.
An article about the strategy for playing The Triangle Game which appears on the NRICH site. It contains a simple lemma about labelling a grid of equilateral triangles within a triangular frame.
What is the largest number of intersection points that a triangle and a quadrilateral can have?
Can you rearrange the cards to make a series of correct mathematical statements?
These proofs are wrong. Can you see why?
Take a number, add its digits then multiply the digits together, then multiply these two results. If you get the same number it is an SP number.
Take any two numbers between 0 and 1. Prove that the sum of the numbers is always less than one plus their product?
Can you invert the logic to prove these statements?
This problem is a sequence of linked mini-challenges leading up to the proof of a difficult final challenge, encouraging you to think mathematically. Starting with one of the mini-challenges, how. . . .
The final of five articles which containe the proof of why the sequence introduced in article IV either reaches the fixed point 0 or the sequence enters a repeating cycle of four values.
In this 7-sandwich: 7 1 3 1 6 4 3 5 7 2 4 6 2 5 there are 7 numbers between the 7s, 6 between the 6s etc. The article shows which values of n can make n-sandwiches and which cannot.
You have twelve weights, one of which is different from the rest. Using just 3 weighings, can you identify which weight is the odd one out, and whether it is heavier or lighter than the rest?
This article discusses how every Pythagorean triple (a, b, c) can be illustrated by a square and an L shape within another square. You are invited to find some triples for yourself.
Advent Calendar 2011 - a mathematical activity for each day during the run-up to Christmas.
Have a go at being mathematically negative, by negating these statements.
An article which gives an account of some properties of magic squares.
Professor Korner has generously supported school mathematics for more than 30 years and has been a good friend to NRICH since it started.
An introduction to some beautiful results of Number Theory
With n people anywhere in a field each shoots a water pistol at the nearest person. In general who gets wet? What difference does it make if n is odd or even?
The first of two articles on Pythagorean Triples which asks how many right angled triangles can you find with the lengths of each side exactly a whole number measurement. Try it!
This article invites you to get familiar with a strategic game called "sprouts". The game is simple enough for younger children to understand, and has also provided experienced mathematicians with. . . .
Start with any whole number N, write N as a multiple of 10 plus a remainder R and produce a new whole number N'. Repeat. What happens?
Follow the hints and prove Pick's Theorem.
Here the diagram says it all. Can you find the diagram?
This is the second article on right-angled triangles whose edge lengths are whole numbers.
Pick a square within a multiplication square and add the numbers on each diagonal. What do you notice?
The first of five articles concentrating on whole number dynamics, ideas of general dynamical systems are introduced and seen in concrete cases.
Can you work through these direct proofs, using our interactive proof sorters?
Find all positive integers a and b for which the two equations: x^2-ax+b = 0 and x^2-bx+a = 0 both have positive integer solutions.
Prove that the internal angle bisectors of a triangle will never be perpendicular to each other.
Peter Zimmerman, a Year 13 student at Mill Hill County High School in Barnet, London wrote this account of modulus arithmetic.
An account of methods for finding whether or not a number can be written as the sum of two or more squares or as the sum of two or more cubes.
By considering powers of (1+x), show that the sum of the squares of the binomial coefficients from 0 to n is 2nCn
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. . . .
We continue the discussion given in Euclid's Algorithm I, and here we shall discover when an equation of the form ax+by=c has no solutions, and when it has infinitely many solutions.
Tom writes about expressing numbers as the sums of three squares.
Is the mean of the squares of two numbers greater than, or less than, the square of their means?
It is impossible to trisect an angle using only ruler and compasses but it can be done using a carpenter's square.
The sum of any two of the numbers 2, 34 and 47 is a perfect square. Choose three square numbers and find sets of three integers with this property. Generalise to four integers.
A polite number can be written as the sum of two or more consecutive positive integers. Find the consecutive sums giving the polite numbers 544 and 424. What characterizes impolite numbers?
To find the integral of a polynomial, evaluate it at some special points and add multiples of these values.
Try to solve this very difficult problem and then study our two suggested solutions. How would you use your knowledge to try to solve variants on the original problem?
Show that x = 1 is a solution of the equation x^(3/2) - 8x^(-3/2) = 7 and find all other solutions.
Prove that you cannot form a Magic W with a total of 12 or less or with a with a total of 18 or more. | <urn:uuid:902f4871-e398-43d2-82bf-823aae88c402> | 3.046875 | 1,470 | Content Listing | Science & Tech. | 64.574358 | 95,492,363 |
Shortly after its discovery in 1942, sodium borohydride (NaBH4) has rapidly become recognized as an extremely convenient reductant 1-3. The borohydrides nowadays are considered as an extremely helpful class of substances in modern organic chemistry and material science. Currently, the diverse boron hydrides derivatives are widely used as selective reducing agents in fine organic synthesis 3-5. Moreover, borohydrides are promising for the hydrogen storage due to their high hydrogen content.6,7 The hydrolysis/alcoholysis processes are certainly significant for the rapid release huge amounts of H2 from borohydrides.
But what factors are exactly influences their reactivity? Researchers from the Laboratory of Metal Hydrides (MH-Lab) have glimpsed in the interplay among boron environment and reactivity of boron hydrides.
Previously it was believed that increased acidity of the proton donor and increased basicity of hydride leads to facilitation of the process of hydrogen release. But, in recent work,11 it was revealed that despite the increase in the rate of the alcoholysis reaction, the substitution of H− by RO− at the boron atom results in a decrease of the basicity of the hydride moiety. In order to explain enhanced reactivity of alkoxyborohydrides, we analyzed the hydride donating ability, equal to free Gibbs energy of the hydride detaching reaction (Figure 1). It was found out that the ability of alkoxyborohydrides to transfer hydride increases upon the consecutive substitution of H− by RO− at the boron atom. This results in a significant facilitation of the cascade BH4– alcoholysis, which energetic profile has a descending sawtooth shape (Figure 2).
Thus, the reactivity of borohydrides is connected with their ability to act as an H– donor that can be increased by B–H bond activation.8 The reactivity of tetra-coordinated borohydrides in reduction processes is substantially determined by the coordination environment of the boron atom. As it has been shown by H. C. Brown 2,3, the modification of parent tetrahydroborate MBH4 provides an effective tool for the fine-tuning its reactivity towards the reactions with hydride transfer as well as the selectivity and stereospecificity of reduction.
As a general rule, the electron withdrawing groups (EWG) increase the electron deficiency (Lewis acidity) of a boron atom, whereas the electron donating groups (EDG) stabilize planar configuration of tricoordinated boranes due to the donation of electron density from the substituents to the empty 2pz orbital of boron atom 9. However, the stability of tetracoordinated boron hydrides [R3BH]− could not be explained solely on the base of electron withdrawing or electron donating ability of the substituent groups 10.
Thermodynamic hydricity, i.e. hydride donating ability (HDA), determined as Gibbs free energy (ΔG°H−) for the reaction in Figure 1 is a very important characteristic of transition metal hydrides that describes their reactivity and is used for the rational design of catalytic reactions 16,17. For that reason, the hydride donating ability (HDA) of borohydrides can also be considered as a measure of their reactivity 18.
However, as it was shown recently by Haiden and Lathem 18, the experimental examination of the hydride donating ability (HDA) of main group hydrides is problematic due to their instability in polar media. Moreover, these compounds have low E–H bond polarizability in comparison with transition metal hydrides and thus the hydride cannot be torn away even in the presence of excess strong Lewis acid. Therefore, the computational methods become extremely helpful in prediction their properties.
Since HDA is a Gibbs free energy (ΔG°H−) of hydride transfer reaction in a chosen media, the lowest HDA value corresponds to the easiest ability of borohydride for hydride transfer to the substrate. Moreover, HDA values are strongly solvent-dependent, in this way switching solvents offers a strategy for changing the Gibbs free energy of hydride transfer (ΔG°H− or HDA) 16. Hence, the evaluation of HDA for various substituted tetracoordinated borohydrides in the media of different polarity in order to pinpoint the ways of B–H bond activation and enhancing the borohydrides reducing power was performed.
However, HDA values for some boranes were previously calculated by Haiden and Lathem 18, but current study was mainly focused on the well-known boron species used for H2 activation or as reducing agents. Some of those compounds are very reactive species, so their reactivity could not be quantified experimentally. Moreover, the analysis of general trends as well as the analysis of substituents impact was not performed.
The hydride donating ability (HDA) values were analyzed for 90 tetracoordinated borohydrides in solvents of different polarity MeCN (ε = 35.7) (HDA varying from 118.2 to 13.4 kcal/mol) and DCM (ε = 8.9) (HDA varying from 124.4 to 18.2 kcal/mol). The analysis of the data obtained shows that the HDA values correlate reasonably well with the Lewis acidity parameters (AN, HA and FA) of parent trigonal boranes (L3B). The substituents at the boron atom provide a useful tool for the increasing a B–H bond reactivity (reduction power) towards the reactions with hydride transfer as well as a fine-tuning of boron hydrides selectivity in the reduction processes.
By varying the number of substituents and their nature, it is possible not only to change the properties of trigonal boranes from highly electrophilic (represented by halogenide- and pseudohalogenide-boranes) to highly nucleophilic (as alkoxy- and amidoboranes), but also to repolarize the boron-bound hydrogen atom and make the proton transfer process more favourable than the hydride transfer. All these findings open new perspectives for further modifications and rational design of new catalytic and reductive systems based on boron hydrides.
These findings are described in the article entitled Hydride donating abilities of the tetracoordinated boron hydrides, recently published in the Journal of Organometallic Chemistry. This work was conducted by Igor E. Golub, Oleg A. Filippov, Natalia V. Belkova, Lina M. Epstein and Elena S. Shubina from the MH-Lab at A.N.Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences (INEOS RAS), Moscow.
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- Titov, A. A.; Guseva, E. A.; Smol’yakov, A. F.; Dolgushin, F. M.; Filippov, O. A.; Golub, I. E.; Krylova, A. I.; Babakhina, G. M.; Epstein, L. M.; Shubina, E. S. Russ. Chem. Bull. 2013, 62, 1829.
- Golub, I. E.; Gulyaeva, E. S.; Filippov, O. A.; Dyadchenko, V. P.; Belkova, N. V.; Epstein, L. M.; Arkhipov, D. E.; Shubina, E. S. J. Phys. Chem. A 2015, 119, 3853.
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- Fleige, M.; Mobus, J.; vom Stein, T.; Glorius, F.; Stephan, D. W. Chem. Commun. (Cambridge, U. K.) 2016, 52, 10830. | <urn:uuid:3c7cb92c-c114-47b9-88b9-919090ed107d> | 2.9375 | 2,947 | Academic Writing | Science & Tech. | 66.019273 | 95,492,364 |
Linux Containers (LXC) is an operating-system-level virtualization method for running multiple isolated Linux systems (containers) on a single control host (LXC host). It does not provide a virtual machine, but rather provides a virtual environment that has its own CPU, memory, block I/O, network, etc. space and the resource control mechanism. This is provided by namespaces and cgroups features in Linux kernel on LXC host. It is similar to a chroot, but offers much more isolation.
- 1 Privileged containers or unprivileged containers
- 2 Setup
- 2.1 Required software
- 2.2 Host network configuration
- 2.3 Container creation
- 2.4 Container configuration
- 3 Managing containers
- 4 Running Xorg programs
- 5 Troubleshooting
- 6 See also
Privileged containers or unprivileged containers
LXCs can be setup to run in either privileged or unprivileged configurations.
In general, running an unprivileged container is considered safer than running a privileged container since unprivileged containers have an increased degree of isolation by virtue of their design. Key to this is the mapping of the root UID in the container to a non-root UID on the host which makes it more difficult for a hack within the container to lead to consequences on host system. In other words, if an attacker manages to escape the container, he or she should find themselves with no rights on the host.
The Arch packages currently provide out-of-the-box support for privileged containers only. This is due to the current Archkernel not shipping with user namespaces configured. This article contains information for users to run either type of container, but additional setup is required to use unprivileged containers at this time.
An example to illustrate unprivileged containers
To illustrate the power of UID mapping, consider the output below from a running, unprivileged container. Therein, we see the containerized processes owned by the containerized root user in the output of
[root@unprivileged_container /]# ps -ef | head -n 5 UID PID PPID C STIME TTY TIME CMD root 1 0 0 17:49 ? 00:00:00 /sbin/init root 14 1 0 17:49 ? 00:00:00 /usr/lib/systemd/systemd-journald dbus 25 1 0 17:49 ? 00:00:00 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation systemd+ 26 1 0 17:49 ? 00:00:00 /usr/lib/systemd/systemd-networkd
On the host however, those containerized root processes are running as the mapped user (ID>100000) on the host, not as the root user on the host:
[root@host /]# lxc-info -Ssip --name sandbox State: RUNNING PID: 26204 CPU use: 10.51 seconds BlkIO use: 244.00 KiB Memory use: 13.09 MiB KMem use: 7.21 MiB
[root@host /]# ps -ef | grep 26204 | head -n 5 UID PID PPID C STIME TTY TIME CMD 100000 26204 26200 0 12:49 ? 00:00:00 /sbin/init 100000 26256 26204 0 12:49 ? 00:00:00 /usr/lib/systemd/systemd-journald 100081 26282 26204 0 12:49 ? 00:00:00 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation 100000 26284 26204 0 12:49 ? 00:00:00 /usr/lib/systemd/systemd-logind
Installingand will allow the host system to run privileged lxcs.
Enable support to run unprivileged contains (optional)
Users wishing to run unprivileged containers need to complete several additional setup steps.
Firstly, a custom kernel is required that has support for User namespaces. This option is available under General setup>Namespaces support>User namespace from an nconfig, or by simply modifying the kernel PKGBUILD with the following line inserted prior to the "make prepare" line:
sed -i -e 's/# CONFIG_USER_NS is not set/CONFIG_USER_NS=y/' ./.config
See, ABS for more on compiling a custom kernel.
/etc/lxc/default.conf to contain the following lines:
lxc.idmap = u 0 100000 65536 lxc.idmap = g 0 100000 65536
Finally, create both
/etc/subgid to contain the mapping to the containerized uid/gid pairs for each user who shall be able to run the containers. The example below is simply for the root user (and systemd system unit):
Host network configuration
LXCs support different virtual network types and devices (see lxc.container.conf(5)). A bridge device on the host is required for most types of virtual networking.
LXC comes with its own NAT Bridge (lxcbr0).
To use LXC's NAT Bridge you need to create its configuration file:
# Leave USE_LXC_BRIDGE as "true" if you want to use lxcbr0 for your # containers. Set to "false" if you'll use virbr0 or another existing # bridge, or mavlan to your host's NIC. USE_LXC_BRIDGE="true" # If you change the LXC_BRIDGE to something other than lxcbr0, then # you will also need to update your /etc/lxc/default.conf as well as the # configuration (/var/lib/lxc/<container>/config) for any containers # already created using the default config to reflect the new bridge # name. # If you have the dnsmasq daemon installed, you'll also have to update # /etc/dnsmasq.d/lxc and restart the system wide dnsmasq daemon. LXC_BRIDGE="lxcbr0" LXC_ADDR="10.0.3.1" LXC_NETMASK="255.255.255.0" LXC_NETWORK="10.0.3.0/24" LXC_DHCP_RANGE="10.0.3.2,10.0.3.254" LXC_DHCP_MAX="253" # Uncomment the next line if you'd like to use a conf-file for the lxcbr0 # dnsmasq. For instance, you can use 'dhcp-host=mail1,10.0.3.100' to have # container 'mail1' always get ip address 10.0.3.100. #LXC_DHCP_CONFILE=/etc/lxc/dnsmasq.conf # Uncomment the next line if you want lxcbr0's dnsmasq to resolve the .lxc # domain. You can then add "server=/lxc/10.0.3.1' (or your actual $LXC_ADDR) # to your system dnsmasq configuration file (normally /etc/dnsmasq.conf, # or /etc/NetworkManager/dnsmasq.d/lxc.conf on systems that use NetworkManager). # Once these changes are made, restart the lxc-net and network-manager services. # 'container1.lxc' will then resolve on your host. #LXC_DOMAIN="lxc"
Then we need to modify the LXC container template so our containers use our bridge:
lxc.net.0.type = veth lxc.net.0.link = lxcbr0 lxc.net.0.flags = up lxc.net.0.hwaddr = 00:16:3e:xx:xx:xx
You also need to install Dnsmasq which is a dependency for lxcbr0.
pacman -S dnsmasq
Then we can start the bridge:
systemctl start lxc-net
If you want the bridge to start at boot-time
systemctl enable lxc-net
For further information including Host bridges users are referred to the Network bridge article.
For privileged containers, simply select a template from
/usr/share/lxc/templates that matches the target distro to containerize. Users wishing to containerize non-Arch distros will need additional packages on the host depending on the target distro:
- Fedora-based: AUR
lxc-create to create the container, which installs the root filesystem of the LXC to
/var/lib/lxc/CONTAINER_NAME/rootfs by default. Example creating an Arch Linux LXC named "playtime":
# lxc-create -n playtime -t /usr/share/lxc/templates/lxc-archlinux
Users wishing to run unprivileged containers should use the -t download directive and select from the images that are displayed. For example:
# lxc-create -n playtime -t download
Alternatively, create a privileged container, and see: #Converting a privileged container to an unprivileged container.
haveged.serviceto avoid a perceived hang during the setup process while waiting for system entropy to be seeded. Without it, the generation of private/GPG keys can add a lengthy wait to the process.
-B btrfsto create a Btrfs subvolume for storing containerized rootfs. This comes in handy if cloning containers with the help of
lxc-clonecommand. ZFS users may use
-B zfs, correspondingly.
The examples below can be used with privileged and unprivileged containers alike. Note that for unprivileged containers, additional lines will be present by default which are not shown in the examples, including the
lxc.idmap = u 0 100000 65536 and the
lxc.idmap = g 0 100000 65536 values optionally defined in the #Enable support to run unprivileged contains (optional) section.
Basic config with networking
System resources to be virtualized/isolated when a process is using the container are defined in
/var/lib/lxc/CONTAINER_NAME/config. By default, the creation process will make a minimum setup without networking support. Below is an example config with networking:
# Template used to create this container: /usr/share/lxc/templates/lxc-archlinux # Parameters passed to the template: # For additional config options, please look at lxc.container.conf(5) ## default values lxc.rootfs.path = /var/lib/lxc/playtime/rootfs lxc.uts.name = playtime lxc.arch = x86_64 lxc.include = /usr/share/lxc/config/archlinux.common.conf ## network lxc.net.0.type = veth lxc.net.0.link = br0 lxc.net.0.flags = up lxc.net.0.name = eth0 lxc.net.0.hwaddr = ee:ec:fa:e9:56:7d # uncomment the next two lines if static IP addresses are needed # leaving these commented will imply DHCP networking # #lxc.net.0.ipv4.address = 192.168.0.3/24 #lxc.net.0.ipv4.gateway = 192.168.0.1
Mounts within the container
For privileged containers, one can select directories on the host to bind mount to the container. This can be advantageous for example if the same architecture is being containerize and one wants to share pacman packages between the host and container. Another example could be shared directories. The syntax is simple:
lxc.mount.entry = /var/cache/pacman/pkg var/cache/pacman/pkg none bind 0 0
Xorg program considerations (optional)
In order to run programs on the host's display, some bind mounts need to be defined so that the containerized programs can access the host's resources. Add the following section to
## for xorg lxc.mount.entry = /dev/dri dev/dri none bind,optional,create=dir lxc.mount.entry = /dev/snd dev/snd none bind,optional,create=dir lxc.mount.entry = /tmp/.X11-unix tmp/.X11-unix none bind,optional,create=dir,ro lxc.mount.entry = /dev/video0 dev/video0 none bind,optional,create=file
If you still get a permission denied error in your LXC guest, then you may need to call
xhost + in your host to allow the guest to connect to the host's display server. Take note of the security concerns of opening up your display server by doing this.
To list all installed LXC containers:
# lxc-ls -f
Users can also start/stop LXCs without systemd. Start a container:
# lxc-start -n CONTAINER_NAME
Stop a container:
# lxc-stop -n CONTAINER_NAME
To login into a container:
# lxc-console -n CONTAINER_NAME
If when login you get pts/0 and lxc/tty1 use:
# lxc-console -n CONTAINER_NAME -t 0
Once logged, treat the container like any other linux system, set the root password, create users, install packages, etc.
To attach to a container:
# lxc-attach -n CONTAINER_NAME
It works nearly the same as lxc-console, but you are automatically accessing root prompt inside the container, bypassing login.
Users with a need to run multiple containers can simplify administrative overhead (user management, system updates, etc.) by using snapshots. The strategy is to setup and keep up-to-date a single base container, then, as needed, clone (snapshot) it. The power in this strategy is that the disk space and system overhead are truly minimized since the snapshots use an overlayfs mount to only write out to disk, only the differences in data. The base system is read-only but changes to it in the snapshots are allowed via the overlayfs.
For example, setup a container as outlined above. We will call it "base" for the purposes of this guide. Now create 2 snapshots of "base" which we will call "snap1" and "snap2" with these commands:
# lxc-copy -n base -N snap1 -B overlayfs -s # lxc-copy -n base -N snap2 -B overlayfs -s
The snapshots can be started/stopped like any other container. Users can optionally destroy the snapshots and all new data therein with the following command. Note that the underlying "base" lxc is untouched:
# lxc-destroy -n snap1 -f
Converting a privileged container to an unprivileged container
Once the system has been configured to use unprivileged containers (see, #Enable support to run unprivileged contains (optional)), AUR contains a utility called
uidmapshift which is able to convert an existing privileged container to an unprivileged container to avoid a total rebuild of the image.
- It is recommended to backup the existing image before using this utility!
- This utility will not shift UIDs and GIDs in ACL, you will need to shift them on your own.
Invoke the utility to convert over like so:
# uidmapshift -b /var/lib/lxc/foo 0 100000 65536
Additional options are available simply by calling
uidmapshift without any arguments.
Running Xorg programs
Either attach to or SSH into the target container and prefix the call to the program with the DISPLAY ID of the host's X session. For most simple setups, the display is always 0.
An example of running Firefox from the container in the host's display:
$ DISPLAY=:0 firefox
Alternatively, to avoid directly attaching to or connecting to the container, the following can be used on the host to automate the process:
# lxc-attach -n playtime --clear-env -- sudo -u YOURUSER env DISPLAY=:0 firefox
Root login fails
If you get the following error when you try to login using lxc-console:
login: root Login incorrect
And the container's
pam_securetty(login:auth): access denied: tty 'pts/0' is not secure !
Alternatively, create a new user in lxc-attach and use it for logging in to the system, then switch to root.
# lxc-attach -n playtime [root@playtime]# useradd -m -Gwheel newuser [root@playtime]# passwd newuser [root@playtime]# passwd root [root@playtime]# exit # lxc-console -n playtime [newuser@playtime]$ su
No network-connection with veth in container config
If you cannot access your LAN or WAN with a networking interface configured as veth and setup through
If the virtual interface gets the ip assigned and should be connected to the network correctly.
ip addr show veth0 inet 192.168.1.111/24
You may disable all the relevant static ip formulas and try setting the ip through the booted container-os like you would normaly do.
... lxc.net.0.type = veth lxc.net.0.name = veth0 lxc.net.0.flags = up lxc.net.0.link =
Cannot start unprivileged LXC due to newuidmap execution failure
Unprivileged LXC cannot start with the currentpackage, because the newuidmap and newgidmap binaries do not have the setuid bit.
$ chmod u+s /usr/bin/newuidmap $ chmod u+s /usr/bin/newgidmap
This is a bug in upstream but still not cherry-picked in official repository | <urn:uuid:1c179790-7bac-4321-a2af-9ed122b39ca8> | 2.921875 | 3,955 | Documentation | Software Dev. | 67.456309 | 95,492,383 |
- Open Access
Global orchestration of gene expression by the biological clock of cyanobacteria
© BioMed Central Ltd 2004
Published: 29 March 2004
Prokaryotic cyanobacteria express robust circadian (daily) rhythms under the control of a central clock. Recent studies shed light on the mechanisms governing circadian rhythms in cyanobacteria and highlight key differences between prokaryotic and eukaryotic clocks.
Rhythmic gene-expression patterns
Circadian biological clocks are self-sustained biochemical oscillators. Their properties include an intrinsic time constant of approximately 24 hours, temperature compensation (so that they run at a period of 24 hours irrespective of temperature), and entrainment to daily environmental cycles . Many biological processes are controlled by these clocks, including gene expression, neuronal activity, photosynthesis, sleeping and waking, and development. Microarray analyses of mRNA expression patterns in eukaryotes have demonstrated that 5-10% of genes exhibit daily rhythms of mRNA abundance. But mRNA abundance is not necessarily comparable with transcriptional activity. For example, microarray and promoter-trap experiments in the eukaryote Arabidopsis have demonstrated that only 6% of genes showed rhythms of mRNA abundance , whereas about 35% of promoters were rhythmically controlled . These results imply that the promoters of many eukaryotic genes are controlled by the biological clock, but that post-transcriptional control mechanisms counterbalance the rhythmic transcriptional activity of some genes so that their mRNA abundances are constant.
KaiC, a master regulator of rhythmic gene expression
In cyanobacteria, there are at least three essential clock-specific genes, kaiA, kaiB, and kaiC, that form a cluster on the chromosome . Some features of kai gene regulation appear reminiscent of the regulation of eukaryotic clock genes. For example, there are rhythms in the abundance of the kaiA and kaiBC transcripts and of the KaiB and KaiC proteins [7, 8]. KaiA, KaiB and KaiC interact with each other [9, 10] and with a histidine kinase, SasA ; these interactions appear to lead to the formation of protein complexes in vivo . KaiC exists in phosphorylated forms in vivo , suggesting another similarity to the post-translational control of eukaryotic clock proteins. KaiA stabilizes KaiC in its phosphorylated form, and KaiB antagonizes the effect of KaiA [8, 13–15]. The ratio of phosphorylated to non-phosphorylated KaiC is correlated with the period at which the clock runs .
Continuous overexpression of KaiC was found to repress the kaiBC promoter (kaiBCp), suggesting negative feedback of KaiC on its own promoter in an analogous fashion to the situation for eukaryotic clock proteins . The kaiBC promoter is not the only target of KaiC, however; the recent paper by Nakahira and coworkers reports the unexpected result that KaiC overexpression represses the rhythms of all promoters in the S. elongatus genome. Intriguingly, this study identified two classes of response to KaiC repression. The first class, termed 'high amplitude' by Nakahira and coworkers , was exhibited by 5-10 % of the promoters, including kaiBCp; these promoters normally show a high-amplitude oscillation that is obliterated by KaiC overexpression (Figure 1e). This pattern reflects promoters whose expression is 'clock-dominated', with practically no basal activity at trough phases or during KaiC overexpression. The second response - exhibited by 90-95% of promoters - is a 'clock-modulated' response, termed 'low amplitude' by Nakahira and coworkers (Figure 1f). This is a lower amplitude oscillation, in which the rhythmic component is abolished by KaiC overexpression, but a significant non-rhythmic basal level remains. These results indicate that KaiC (probably as part of a complex) coordinates genome-wide gene expression; the majority of genes have significant basal activity and are rhythmically modulated by the KaiABC oscillator, while in a smaller subset of genes, the oscillator dominates transcriptional activity (Figure 1e,1f) . This latter class might turn out to contain genes that encode proteins intrinsically involved in the cell's circadian-clock system.
Considerable evidence indicates that circadian feedback loops in eukaryotes are autoregulatory, whereby clock proteins directly or indirectly regulate the activity of their own genes' promoters . It was therefore a surprise to discover that the kai promoters are dispensable; Kai proteins can be expressed from a heterologous promoter and the cyanobacterial clock ticks along unperturbed [15, 16]. The cyanobacterial transcriptional apparatus recognizes the heterologous promoter (in this case trcp from E. coli), but trcp is obviously not a promoter that evolved in conjunction with cyanobacterial clock genes. We first reported the functional replacement of kaiBCp , and now Nakahira and coworkers report the functional replacement of both kaiAp and kaiBCp. Both studies found that expression of the Kai proteins needs to be within a permissive window of intracellular concentration to permit rhythmicity [15, 16]. Thus, the circadian feedback loop in cyanobacteria does not require negative feedback of clock proteins upon specific clock promoters; apparently all that is required is the expression of an appropriate level of Kai proteins. Even temperature compensation - a defining characteristic of circadian clocks - is preserved when trcp replaces kaiBCp .
An oscilloid model for the circadian system
The pervasiveness of rhythmic transcriptional activity, and the fact that the clockwork does not require specific clock-gene promoters, suggests a broadly global mechanism for the cyanobacterial clock system. But what is the basis of this global regulation? One possibility could be rhythmic control by RNA polymerase sigma subunits, which often determine the promoter specificity of the polymerase. But studies of sigma subunits in cyanobacteria have not yielded explanations for global regulation . An alternative is the possibility that chromosomal topology is involved. The chromosome in most bacteria is organized into a 'nucleoid', which has a highly organized architecture based on condensation and coiling of DNA . It is well known that changes in the local supercoiling status of DNA can affect the transcriptional rate of genes , and our findings concerning the behavior of promoters in cyanobacteria support those observations . We proposed in 2001 that KaiC might mediate both its own negative feedback regulation and global regulation of the cyanobacterial genome by orchestrating oscillations in the condensation and/or supercoiling status of the entire cyanobacterial chromosome .
At present, it appears that the clock system in cyanobacteria is different from that in eukaryotes, and that changes in chromosomal topology could be a key element. In the fullness of time, however, we might find rhythmic modulation of chromosomal structure to be important in eukaryotic clock regulation - indeed, suggestive evidence for that hypothesis already exists for the mammalian clock . If this proves to be the case, the investigations of the cyanobacterial clock may lead to fundamental insights that are broadly applicable to all organisms.
I thank Takao Kondo and Susan Golden for a productive and exciting collaboration on cyanobacterial clocks. I am grateful for support from the National Science Foundation and the National Institutes of Health.
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Researchers from Kansas State University in the US successfully used short pulses of ultra-intense high-energy X-rays to produce a detailed picture of how X-ray radiation interacts with molecules.
This was the first time this kind of extreme light has been used to break up molecules, and it may help understand the damages from X-ray radiation when it is used to take an X-ray picture, researchers said.
The team shot iodomethane (CH3I) and iodobenzene (C6H5I) molecules with a powerful X-ray beam.
"As this powerful X-ray light hits a molecule, the heaviest atom, the iodine, absorbs a few hundred times more X-rays than all the other atoms," said Artem Rudenko, assistant professor at Kansas State University.
"Then, most of its electrons are stripped away, creating a large positive charge on the iodine," Rudenko said. "The X-ray laser is the most powerful in the world with an intensity of 100 quadrillion kilowatts per square centimetre," he continued.
The positive charge that was created steadily pulls electrons from the other atoms in the molecule, which fills the created vacancies like a short-lived black hole, researchers said.
"The cycle repeats itself until the molecule explodes" said Daniel Rolles assistant professor at Kansas State University.
"In total, 54 of iodomethane's 62 electrons were ejected in this experiment, far more than we anticipated based on earlier studies using less intense X-rays. In addition, the larger molecule, iodobenzene, loses even more electrons," he said.
Ultra-intense X-rays give a new and efficient tool to image biological particles, such as proteins and viruses, with high resolution, researchers said.
"Based on our findings, we can predict what will happen in larger systems," Mr Rolles said.
The study was published in the journal Nature. | <urn:uuid:d407bf28-75a6-49e0-9db8-66291b90bc09> | 3.640625 | 400 | News Article | Science & Tech. | 35.524942 | 95,492,402 |
A View from Emerging Technology from the arXiv
Gravity Ruled Out as the Cause of the Pioneer Anomaly
If the strange deceleration of the Pioneer spacecraft is caused by gravity, then it should also act on other bodies in the outer solar system. That doesn’t seem to be the case.
The Pioneer anomaly is an unexplained deceleration of the Pioneer 10 and 11 spacecraft that seems to be acting on them as they head out of the Solar System. This deceleration is tiny: just (8.74±1.33)×10^−10 ms^−2. The big question is where does it come from.
One possibility is that the deceleration is the result of some long range gravitational force that is not observed on Earth. But if that’s the case, then this force should act on all of the many objects in the outer Solar System.
Earlier this year, we looked at one study of the orbit of Pluto which was unable to rule out the possibility that a Pioneer-like force acts on it because Pluto’s orbit is so poorly known.
Today we look at a similar study in which the objects of attention are the major Neptunian satellites: Triton, Nereid and Proteus. Earlier this year, astronomers published the result of a new analysis of the motion of these bodies taken over several orbits.
Now Lorenzo Iorio, at the Istituto Nazionale di Fisica Nucleare in Pisa, Italy, has analysed these orbits and concludes that a Pioneer-like force cannot be acting on Triton, Nereid and Proteus because the resulting anomalous perturbations would be too large to have escaped detection.
“The possibility that the Pioneer anomaly may be an exotic gravitational phenomenon seems to be challenged,” says Iorio.
This work is part of a growing body of evidence that the Pioneer anomaly is not a gravitational effect.
That’s a puzzle. If not gravitational in origin, what kind of force is acting on the Pioneer spacecraft?
Ref: arxiv.org/abs/0912.2947: Does the Neptunian System of Satellites Challenge a Gravitational Origin For The Pioneer Anomaly?
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:4364846b-6e85-409e-a5cb-5c341d0cdfb5> | 2.875 | 498 | Truncated | Science & Tech. | 48.435409 | 95,492,404 |
posted by jim
If a seed is planted, it has a 95% chance of growing into a healthy plant.
If 6 seeds are planted, what is the probability that exactly 4 don't grow?
If the events are independent, the probability of both/all events occurring is determined by multiplying the probabilities of the individual events.
(.95^2)(.05^4) = ? | <urn:uuid:f5bf64f0-516f-4507-8cd0-757d391e7574> | 3.0625 | 82 | Q&A Forum | Science & Tech. | 68.375 | 95,492,438 |
|Scientific Name:||Alburnus nasreddini Battalgil, 1943|
|Taxonomic Source(s):||Battalgil, F. 1943. Türkiye'de yeni tatli su baliklari. Nouveau poissons des eaux douces de la Turquie. Revue de la Faculté des Sciences de l'Université d'Instanbul, Série B: Sciences Naturelles 9(2): 126-133.|
|Red List Category & Criteria:||Critically Endangered B1ab(i,ii,iii,iv,v) ver 3.1|
|Reviewer(s):||Ekmekçi, F., Küçük, F., Sarı, H., Özuluğ, M. & Smith, K.|
This species was present in two large lakes from where it has vanished due to pollution and desiccation of the lakes. It is now only known from one lake tributary (estimated at 10 km long). The population in this tributary is suspected to be declining due to water abstraction and pollution. It is therefore assessed as Critically Endangered.
The species is known from Eber and Akşehir lakes, Turkey, including the inflowing streams. However the species is now only found in one tributary (Ortaköy - estimated at 10 km long) of Lake Akşehir only. Bleaks of Lake Ilgin basin may also belong to this species but due to taxonomic uncertainties, this population is ignored for the assessment.
|Range Map:||Click here to open the map viewer and explore range.|
The only remaining population is at one inflowing stream (Ortaköy) to Lake Akşehir. The species has declined and disappeared from most of its range.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:|
This was a lacustrine species with small resident populations in tributaries. The lacustrine parts of the population are lost and it now only inhabit streams with moderately or slowly flowing water.
|Movement patterns:||Not a Migrant|
|Major Threat(s):||Massive water abstraction has reduced the lake levels drastically and heavy pollution has made them to an uninhabitable place for fishes. The remaining population in Örtaköy stream face high pollution levels as well as often very low water levels due to water abstraction. Growing human populations will increase water abstraction in future and climate change induced less rainfall will shrink the available water resources.|
|Conservation Actions:||There is no conservation in place for this species, but both lakes are protected areas. The only known stream inhabited by this species is not protected. Habitat restoration and biodiversity oriented water resource management would help to save the unique freshwater biodiversity of theses lake basins. Fieldwork is further recommended to better understand the distribution of the species and threats in the lake tributaries.|
|Citation:||Freyhof, J. 2014. Alburnus nasreddini. The IUCN Red List of Threatened Species 2014: e.T19018610A19222793.Downloaded on 22 July 2018.|
|Feedback:||If you see any errors or have any questions or suggestions on what is shown on this page, please provide us with feedback so that we can correct or extend the information provided| | <urn:uuid:785b6124-0095-43a5-9857-5e6c1088626e> | 3.046875 | 727 | Knowledge Article | Science & Tech. | 43.469083 | 95,492,453 |
Tiny billionth-of-a-meter sized clusters of gold atoms — gold “nanoparticles” — are being widely studied by scientists. They have many useful potential applications, from carriers for cancer-treatment drugs to digital data storage. But many of these applications, particularly those in electronics, require that the nanoparticles form ordered arrays that can be hard to achieve. At Arizona State University (ASU), researchers have discovered that grids made of DNA strands are excellent templates for neatly organizing gold nanoparticles.
“The collective properties of nanoparticles are heavily dependent on how the particles are grouped. Achieving an even spacing between the particles is particularly important, but can be difficult,” said the study’s lead scientist, ASU chemist Hao Yan. “However, when deposited onto a DNA grid the particles fall neatly into patterns with little effort on our part.”
Yan and his research group used gold nanoparticles that were five nanometers in diameter. Rather than being bare, the particles were coated with a layer of DNA “pieces,” called “T15 sequences,” which radiated from the particles’ surfaces like arms. The scientists then deposited the particles onto lattices formed by two types of cross-shaped DNA “tiles”, “A” tiles and “B” tiles, that bind together in an alternating fashion to form the DNA grid.
At regular intervals, each A tile contained a short single strand (called an “A15” strand) that protruded out of the tile surface. These strands served as tethering points for the T15-coated nanoparticles, allowing the particles to stick to the DNA surface, a bit like DNA-nanoparticle “Velcro.”
This configuration caused the nanoparticles to “self assemble” into a square pattern — each particle sitting on one A tile — with a nearly constant particle-particle distance of about 38 nanometers. The group confirmed this using an atomic force microscope, a very powerful imaging device.
However, this result, while welcomed by the scientists, wasn’t exactly what they expected.
“We were pleased that the gold nanoparticles formed a very regular square pattern, but it wasn’t quite the pattern we thought we’d see,” said Yan. “If you picture nine DNA tiles forming a square, we predicted that five particles would be organized on the square — one on each corner and one in the middle. But the pattern we observed lacked that middle particle.”
The scientists guess that this is due to the T15 sequence layer, which effectively increases the diameter of each nanoparticle and, moreover, makes each particle highly negatively charged. As a result, the nanoparticles repel each other if they are too close together, which limits the minimum particle-particle distance. Therefore, a particle located at the center of the square would violate this limit.
In future research, Yan and may try to use this organization method to form more complex nanoparticle arrays, such as denser patterns or patterns of different shapes, by altering the particles’ DNA coating.
Citation: “Periodic Square-Like Gold Nanoparticle Arrays Templated by Self-Assembled 2D DNA Nanogrids on a Surface,” Nano Lett., Vol. 6, No. 2, 248-251 (2006)
by Laura Mgrdichian, Copyright 2006 PhysOrg.com
Explore further: DNA drives design principles for lighter, thinner optical displays | <urn:uuid:93e63cce-b1a4-4535-bd31-0a8826d3be23> | 4 | 742 | News Article | Science & Tech. | 32.696582 | 95,492,456 |
Some Sun-like stars are known for their ability to ingest large amounts of the rocky material from which "terrestrial" planets like Earth, Mars and Venus are made. New research on these "Earth-eater" stars may provide scientists with clues about the formation of planets as well as assist in the ongoing search for Earth-like exoplanets, according to astronomers.
Magnetars are an unusual variant of a neutron star that have a extraordinarily powerful magnetic pull, despite their tiny size. It has long been a mystery how our galaxy's only magnetar ever came to be, as conventional wisdom said that it should have formed a black hole. Now, scientists believe they have discovered the answer.
Engineers are preparing to blast away the top of a Chilean mountain to make way for the European Extremely Large Telescope (E-ELT). | <urn:uuid:80bf2844-c572-49fd-9eab-68f5b9f45069> | 3 | 170 | Content Listing | Science & Tech. | 36.640258 | 95,492,469 |
But reefs appear to be more resistant to one potential menace – seaweed – than previously thought, according to new research by a team of marine scientists from the United States and Australia.
Their study, published in the June issue of the journal Ecology, is the first global-scale analysis of thousands of surveys of individual reefs – in all, more than 3,500 examinations of about 1,800 reefs performed between 1996 and 2006.
“Until now, many scientists have concluded that the world’s coral reefs are being overrun by seaweed,” said John Bruno, Ph.D, associate professor of marine sciences at the University of North Carolina at Chapel Hill and lead author of the study. “Our findings show that’s not the case. Seaweed have taken over and are dominating some reefs, but far fewer than assumed.”
The problem with too much seaweed, researchers say, is that it can smother the baby corals, reducing the ability of reefs to recover from other disturbances such as hurricanes and disease outbreaks. Over recent decades, there have been several dramatic examples of such shifts, with one of the most widely known and striking cases occurring in the Caribbean in the 1980s. Following a series of events that disturbed the marine environment (including two major hurricanes, a disease outbreak and the loss of a seaweed-grazing urchin), coral cover on several reefs in Jamaica plummeted from about 70 percent to less than 10 percent, and macroalgae became the dominant life form.
So Bruno, along with colleagues Hugh Sweatman, Ph.D., from the Australian Institute of Marine Science and William F. Precht, a Florida-based marine ecologist, set out to determine how bad and how widespread the problem of seaweed-dominated reefs really is.
The team came up with a “phase-shift index” to determine the state of each reef. Pristine reefs where coral was still abundant had an index number of -2 to -3, while areas where macroalgae have overwhelmed reefs’ surfaces were given an index ranking of between 3 and 5.
They found that while there were moderate local increases in seaweed cover over the study period, only four percent of reefs worldwide were dominated by macroalgae – that is, more than 50 percent of a reef’s surface was covered in seaweed. Researchers also found overall “phase shift severity” decreased in the Caribbean, did not change in the Florida Keys and the Indo-Pacific, and increased slightly on the Great Barrier Reef due to moderate coral loss.
“Overall, our results indicate that there is no general recent trend (i.e., post-1995) toward marcoralgal dominance,” the researchers wrote.
“The results from this study question many of the prevailing paradigms that coral reef ecologists have developed over the past two decades,” Precht said. “These findings will change the way we view and manage these fragile yet resilient ecosystems.”
Said Sweatman: “I hope this study leads to clearer definition of what coral-algal phase shifts are and broadens our perspective on the serious loss of corals in many parts of the world. Australian reefs have been relatively lucky so far, but there is no reason for complacency.”
The study team noted that while their analysis suggests the threat posed by macroalgae has been exaggerated, individual case studies such as the degradation of Jamaican reefs have been invaluable warnings of the consequences of subjecting reefs to multiple natural and manmade disturbances.
The paper’s co-authors include UNC College of Arts and Sciences marine sciences department researchers Elizabeth R. Selig, Ph.D., and Virginia G. W. Schutte, who is now a doctoral student at the University of Georgia.
The study was funded by the National Science Foundation, the Australian Institute of Marine Science and UNC-Chapel Hill.
Ecology Journal Web site: http://www.esajournals.org/loi/ecol
Patric Lane | Newswise Science News
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
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Isotope dating information
Isotopes are distinguished from each other by giving the combined number of protons and neutrons in the nucleus.For example, uranium 235 is the isotope of uranium that has 235 protons and neutrons in its nucleus rather than the more commonly occurring 238. noun A nearly identical person; near double: Like his isotope Paglia, Rush Limbaugh can be counted on to bury the occasional nugget of truth beneath his avalanche of infuriating extrapolation and phony statistics/It actually IS you.
A method for determining the age of an object based on the concentration of a particular radioactive isotope contained within it.He was employed at Caltech's Division of Geological & Planetary Sciences at the time of writing the first edition.He is presently employed in the Space & Atmospheric Sciences Group at the Los Alamos National Laboratory.In some cases radiation can be used to treat diseased organs, or tumours.Five Nobel Laureates have been closely involved with the use of radioactive tracers in medicine.The attributes of naturally decaying atoms, known as radioisotopes, give rise to several applications across many aspects of modern day life (see also information paper on The Many Uses of Nuclear Technology).
There is widespread awareness of the use of radiation and radioisotopes in medicine, particularly for diagnosis (identification) and therapy (treatment) of various medical conditions.
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. 1979, 1986 © Harper Collins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012 Cite This Source (ī'sə-tōp') One of two or more atoms that have the same atomic number (the same number of protons) but a different number of neutrons.
Carbon 12, the most common form of carbon, has six protons and six neutrons, whereas carbon 14 has six protons and eight neutrons.
It has become increasingly clear that these radiometric dating techniques agree with each other and as a whole, present a coherent picture in which the Earth was created a very long time ago.
Further evidence comes from the complete agreement between radiometric dates and other dating methods such as counting tree rings or glacier ice core layers.
The amount of the isotope in the object is compared to the amount of the isotope's decay products. | <urn:uuid:416a78a4-5220-40d0-a028-2cc737c68123> | 3.59375 | 486 | Knowledge Article | Science & Tech. | 29.5325 | 95,492,482 |
An international scientific team has developed a new method of probing topological structures and their topological phase transitions. The method is based on examining the reflection spectrum of electromagnetic waves reflecting off an object from different impact angles. The accuracy of the method's results has been verified experimentally in both IR and microwave spectra. Results were published in Nature Communications.
Topology is the study of the properties of objects that remain unchanged during deformation. From a topological point of view, a doughnut and a mug are the same since they both have a hole in the center. Topological invariants lie at the core of many important observable properties of matter. They are incorporated in the creation of new, unusual materials, which are used, for example, to control light propagation in optical systems.
To detect topologically non-trivial structures, scientists usually scan the propagation of an object's near-field. In other words, they monitor an object's emissions at a distance much smaller than a wavelength. The resulting near-field map lets them draw conclusions about the topology of the object's photonic bands. For instance, it is possible to determine if the object contains any topological edge states, and to what degree they are protected from scattering in areas with defects or non-uniformity.
Scientists from ITMO University together with their colleagues from the City University of New York have proposed a new method of topological analysis based on spectroscopy of an object's far-field. "We posed the question: Do the topological properties of a system affect how it disperses light at long distances?" says Maxim Gorlach, research fellow at ITMO's Metamaterials Laboratory. "To answer it, our colleagues, led by Alexander Khanikaev, developed and manufactured two two-dimensional structures using silicon cylinders of slightly different geometric parameters. One was trivial, and the other topological."
Making such structures isn't easy, say the scientists. For that, they need to use the latest nanofabrication methods. Having analyzed the resulting samples' spectra, they developed a theoretical model depicting the results of the analysis. It allowed them to determine the structure's topological invariant. This model later became the basis for the far-field spectroscopy method.
"At some point, our reviewers expressed interest in whether we can confirm that the results we got through far-field analysis are in line with the standard technique of near-field analysis. To do that, we conducted a microwave experiment. We created a metasurface of two parts: one topologically trivial and one non-trivial. Our goal was to observe the topological state localized on the border of these two parts. In the end, we managed to produce an all-dielectric metasurface which contains topologically-protected states in the microwave band. At the same time, the polarization of the edge state turned out to be unequivocally connected to the direction of its propagation. The experiment confirmed the accuracy of our model, and the article was accepted," adds Dmitry Zhirihin, Ph.D. student at ITMO University Faculty of Physics and Engineering.
The new method's advantage is that it lets researchers study the topology of objects from a distance. "We no longer need to examine the propagation field right on the surface of the structure. We can now detect unusual topological states in materials from afar. In addition, as we developed the method, we proved that while energy loss can occur in topological structures, topological edge states still persist," notes Maxim Gorlach. "We are now planning to use the new method to study three-dimensional topological insulators and we are expecting some new and exciting results."
Earlier on, topological states were only suggested for use in secure signal transmission. But now, explain the scientists, the range of applications is becoming much wider. "It is known that nanofabrication methods are limited in precision due to various technological reasons – and photonic nanostructures are guaranteed to contain defects. This leads to loss of efficiency and accuracy of the devices produced with these methods. For example, any biosensor made using nanofabrication methods will be limited in the accuracy of its measurements, all due to the defects. Using topological states in the construction of these detectors, we can increase their sensitivity and precision – even despite the presence of structural defects," says project lead Alexander Khanikaev.
Explore further: Switching conduction mode—a step towards topological transistors
Maxim A. Gorlach et al. Far-field probing of leaky topological states in all-dielectric metasurfaces, Nature Communications (2018). DOI: 10.1038/s41467-018-03330-9 | <urn:uuid:08413c01-5e6c-44b1-9cfb-a6e515d827d7> | 3.6875 | 977 | News Article | Science & Tech. | 26.726087 | 95,492,508 |
A devastating snowfall predicted for Northwest Montana in early 2018 is fake news. There is no truth to a report that meteorologists from National Aeronautics and Space Administration (NASA), an independent agency of the executive branch of the United States federal government responsible for the civilian space program, as well as aeronautics and aerospace research, predicted a heavy snowfall.
Where did this fake news originate? React365 published the fake news article claiming that a devastating snowfall will happen in Montana in early 2018. You can read the fake news below.
Meteorologists at NASA’s Charles Darwin Research Facility have recently discovered a disturbing cosmic anomaly that they are certain will cause record snowfalls to hit the entire Northwest Corridor this coming winter. Northwest Montana will face the brunt of this storm, with snowfall levels predicted to reach 34 feet in the month of January alone. If that’s not enough, winds of up to 120 mph are predicted to prevail throughout most of the latter half of January, and into early February.
“It’s something we’ve never seen before, and it’s a real concern. People need to be aware of this, so they can start evacuation preparations immediately. Winter is coming.”, said Jack Moff – Chief Analyst of the elite NASA research team.
Residents of the affected areas are urged to find alternate living arrangements as soon as possible. We’ll update this article soon, as more information becomes public.
However, there is no truth to the above story, according to Hoax Alert.
A search for a NASA-operated “Charles Darwin Research Facility” does not come up with any results. The thing that comes closest is the Charles Darwin Research Station on the Galapagos Islands in the Pacific Ocean which is not operated by NASA. Rather, the Charles Darwin Research Station is a research facility housing an extensive collection of preserved specimens of Galápagos plant life.
Furthermore, React365 is a prank website that allows users to submit a headline, description and photo to create prank news articles. React365 carries a disclaimer at the bottom of every page:
This website is an entertainment website, news are created by users. These are humourous news, fantasy, fictional, that should not be seriously taken or as a source of information.
The Almanac is predicting the following for Billings, Mont., for November 2017 through October 2018.
Winter will be warmer than normal, with slightly above-normal precipitation. The coldest periods will be from late November into early December and from late December into early January. Snowfall will be below normal in the north and above in the south, with the snowiest periods in mid- and late November, mid- to late December, and early to mid-March. April and May will be cooler than normal, with precipitation a bit above normal. Summer will be a bit hotter than normal, with slightly below normal rainfall. The hottest periods will be in early and mid- to late July and mid-August. September and October will be cooler than normal, with slightly above normal rainfall.
What did you think of the fake news that a devastating snowfall was predicted for Northwest Montana in early 2018? Did you believe the fake news or see people sharing it falsely on social media? Let us know in the comments section. | <urn:uuid:d19159e7-1d21-4285-b658-0a9f5db1d300> | 2.953125 | 680 | Personal Blog | Science & Tech. | 43.40155 | 95,492,546 |
The death of a massive star in a distant galaxy 10 billion years ago created a rare superluminous supernova that astronomers say is one of the most distant ever discovered. The brilliant explosion, more than three times as bright as the 100 billion stars of our Milky Way galaxy combined, occurred about 3.5 billion years after the Big Bang at a period known as "cosmic high noon," when the rate of star formation in the universe reached its peak. The researchers reported their findings in a paper published on July 21 in the Monthly Notices of the Royal Astronomical Society.
Superluminous supernovae are 10 to 100 times brighter than a typical supernova resulting from the collapse of a massive star. But astronomers still don't know exactly what kinds of stars give rise to their extreme luminosity or what physical processes are involved.
The yellow arrow marks the superluminous supernova DES15E2mlf in this false-colour image of the surrounding field. This image was observed with the Dark Energy Camera (DECam) gri-band filters mounted on the Blanco 4-metre telescope on December 28, 2015, around the time when the supernova reached its peak luminosity.
Credit: D. Gerdes / S. Jouvel
The supernova known as DES15E2mlf is unusual even among the small number of superluminous supernovae astronomers have detected so far. It was initially detected in November 2015 by the Dark Energy Survey (DES) collaboration using the Blanco 4-metre telescope at the Cerro Tololo Inter-American Observatory in Chile.
Follow-up observations to measure the distance and obtain detailed spectra of the supernova were conducted with the Gemini Multi-Object Spectrograph on the 8-metre Gemini South telescope. The investigation was led by UC Santa Cruz astronomers Yen-Chen Pan and Ryan Foley as part of an international team of DES collaborators.
The new observations may provide clues to the nature of stars and galaxies during peak star formation. Supernovae are important in the evolution of galaxies because their explosions enrich the interstellar gas, from which new stars form with elements heavier than helium (which astronomers call "metals").
"It's important simply to know that very massive stars were exploding at that time," said Foley, an assistant professor of astronomy and astrophysics at UC Santa Cruz. "What we really want to know is the relative rate of superluminous supernovae to normal supernovae, but we can't yet make that comparison because normal supernovae are too faint to see at that distance. So we don't know if this atypical supernova is telling us something special about that time 10 billion years ago."
Previous observations of superluminous supernovae found they typically reside in low mass or dwarf galaxies, which tend to be less enriched in metals than more massive galaxies. The host galaxy of DES15E2mlf, however, is a fairly massive, normal-looking galaxy.
"The current idea is that a low-metal environment is important in creating superluminous supernovae, and that's why they tend to occur in low mass galaxies, but DES15E2mlf is in a relatively massive galaxy compared to the typical host galaxy for superluminous supernovae," said Pan, a postdoctoral researcher at UC Santa Cruz and first author of the paper.
Foley explained that stars with fewer heavy elements retain a larger fraction of their mass when they die, which may cause a bigger explosion when the star exhausts its fuel supply and collapses. "We know metallicity affects the life of a star and how it dies, so finding this superluminous supernova in a higher-mass galaxy goes counter to current thinking," Foley said.
"But we are looking so far back in time, this galaxy would have had less time to create metals, so it may be that at these earlier times in the universe's history, even high-mass galaxies had low enough metal content to create these extraordinary stellar explosions. At some point, the Milky Way also had these conditions and might have also produced a lot of these explosions."
"Although many puzzles remain, the ability to observe these unusual supernovae at such great distances provides valuable information about the most massive stars and about an important period in the evolution of galaxies," said Mat Smith, a postdoctoral researcher at the University of Southampton. The Dark Energy Survey has discovered a number of superluminous supernovae and continues to see more distant cosmic explosions revealing how stars exploded during the strongest period of star formation.
Tim Stephens | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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Diatoms are an important and often dominant component of periphyton, and their contribution to primary production in aquatic systems has largely been underestimated. Apart from the qualitative and quantitative importance of diatoms in the periphyton, the study of diatoms has the added value that they are excellent environmental indicators, since they are present in almost all aquatic habitats and react with speed and sesitivity to environmental changes.
General Introduction/ Study area (Empord# wetlands/ The salt marshes of the Empord# Wetlands Natural Park)/ Material and Methods/ Factors favouring the predominance of different types of aquatic primary producers (phytoplankton - peiphyton - macrophytes) in lentic waters of Empord# wetlands/ Diatom taxa of the salt marshes of the Empord# wetlands (Check-list/ Diatom taxa of problematic taxonomy/ Plates)/ Factors affecting periphytic Diatom communities in the salt marshes of Empord# wetlands/ Morphological variation of Nitzschia frustulum as a response to changes in some environmental variables/ General discussion/ Conclusions/ References/ Appendix I (Taxa acronyms)/ Appendix II (Relative abundance of the species by months and by waterbodies).
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posted by joy
[20 pts] A 2.00 kg block is pushed against a spring with negligible mass and force constant k = 400 N/m, compressing it 0.220 m. When the block is released, it moves along a frictionless, horizontal surface and then up a frictionless incline with slope 37 degrees. (a) What is the speed of the block as it slides along the horizontal surface after having left the spring? (b) How far does the block travel up the incline before starting to slide back down?
For (a), assume all of the stored sproing potential energy is coinverted to kinetic energy.
(1/2)kX^2 = (1/2)mV^2
V = sqrt(k/m)* X
where X (=0.22 m) is the amount of spring compression and k is the spring constant, 400 N/m.
For (b), assume all of the initial stored potential energy is converted to gravitational potential energy.
(1/2)kX^2 = m g x' sin 37.
Solve for the distance x' that it slides. | <urn:uuid:d84ddaf7-64ed-49f0-9444-1c53d130daaf> | 3.8125 | 241 | Q&A Forum | Science & Tech. | 88.41734 | 95,492,643 |
On April 30, NASA’s Messenger space probe bit the dust on the planet Mercury. After a decade-long mission of studying the closest planet to the sun, the spacecraft ran out of options for adjusting its pointing and spiraled into the surface.
Messenger had been only the second spacecraft – after a couple of fly-bys by NASA’s Mariner 10 in the 1970s – to get close-up views and data. It yielded many unexpected discoveries, as these missions tend to do, including evidence of volcanic activity and the signature of ice in some craters at Mercury’s north pole that never see direct sunlight. This, on top of making the best images and maps of the planet.
You can see Mercury yourself right now: It is close to its highest position for the year in the western dusk sky. Look for it low in the west-northwest, about a fist’s-width at arm’s length above the horizon, as soon after sunset as the darkening sky allows. Higher in the sky, in the same direction, you will see the much-brighter planet Venus. Mercury is a dark planet, reflecting about the same percent of sunlight as the moon – around 12 percent – while Venus is covered in bright clouds that reflect three quarters of the sunlight.
Higher yet in the sky you will find Jupiter and, later in the evening, Saturn rises in the southwestern sky. Only Mars is unavailable, hidden in the glare of the sun. We could throw in Uranus and Neptune in the dawn sky, but you can’t see them without a telescope.
NASA has explored all of these planets and even has the New Horizons space probe headed to a summertime encounter with the celestial body formerly known as the planet Pluto. We can expect the unexpected again.
Why explore the planets? Besides satisfying our species’ natural curiosity, we need to understand the other planets to perhaps get a glimpse of possible fates for Earth. Undeniable evidence now exists that Mars once had a lot of water, enough to flow over its surface and to produce sediments. How did Mars lose its water? Those clouds on Venus are sulfuric acid (think of that stuff that corrodes your car battery terminals) and are in a mostly carbon dioxide atmosphere (think fossil fuel combustion product). Venus is trapped in a runaway greenhouse effect that keeps it extremely hot. Could these scenarios be part of our future?
We have a lot to learn from studying the other planets. After all, it is hard to generalize your knowledge of planets based on a sample of one: Earth. And as important, they may teach us a lesson on why we need to take care of ours.
Daniel B. Caton is a physics and astronomy professor and director of observatories at Appalachian State University. Email: email@example.com. More on this month’s column: www.upintheair.info. | <urn:uuid:ab27a6b1-f3d1-4a82-b489-b67bf6f9f5ef> | 4.03125 | 602 | News Article | Science & Tech. | 55.738137 | 95,492,644 |
Yesterday someone remarked: With Apache you cant implement multiple SSL certificates behind one and the same IP address. This remark is actually not quite correct. A good opportunity to explain the basics behind SSL and explain why SSL implementations on servers with multiple sites can be challenging.
SSL is an acronym for ‘Secure Socket Layer’ and is a method to encrypt traffic between client and host. SSL uses a key-pair that is provided by a digital certificate to encrypt the communication. To do this, SSL needs inform the client how to decrypt the traffic prior to the actual communication. This is done by the so called, SSL-handshake, in which a public-key is shared with the client.
Each of the parties (client and host) now have a public and private key available. With this so called keypair both parties are able to encrypt and decrypt the traffic that is being send. Please view the Deffie-Hellman key exchange wikipedia for a clear example of this algorithm.
The Deffie-Hellman example also illustrates the risk of a client losing or sharing its private key.
What is an certificate
In most cases an certificate has multiple purposes. One is obviously to encrypt the traffic. An additional task is to identify the host to the client. The host is usually identified using its public DNS name. By means of the CN (Common Name) field of the certificate, the client is able tot verify that the CN in the certificate is equal to the DNS adres the client is visiting. If either one is not equal, the client will generate an warning.
Why do you still get an warning when you use a valid DNS name in your certificates CN field? Well an additional check is necessary. An external Certificate Authority needs to back your claim. This is done by signing the certificate using an certificates private key that is only known by the Certificate Authority. The client is now able to check (with the public key of that CA) the validity of your certificate and its claim.
You might now understand why there was such a buzz over Diginotar making its private key available to hackers using its auto-signing process.
What is a SOCKET
The second principle to understand is the ‘socket.’ Litteraly a socket is an communication endpoint used by an application to send data. Its important to realize that a socket only contains protocol information (like TCP/UDP or ICMP) and various settings like timeout. Usually IP information isnt given in the socket definition. If a programmer wants the socket to be open on a specific device he usually needs to ‘explicitly bind’ the socket to that IP.
So an socket is nothing more than a ‘door’ to the network that an application can programmatically use to send data over an networked device.
Apache and SSL
In case of Apache httpd SSL is implemented on a listening IP:Port. When a client connects to Apache using the ip:port configured in httpd.conf the first thing that is performed is the SSL handshake. As we noted, the SSL handshake is performed prior to sending actual data. When this is completed, the http request header is send (encrypted) to the Apache instance.
When Apache implements multiple sites behind one socket, called virtual hosts, it uses the ‘http GET header’ to determin the right content (virtual host). Apache can only do this when it received a valid requestheader, that can only be offered after SSL has been implemented.
Now here is the issue.
The http request header we are talking about actually contains a DNS site name, for instance: http://www.google.com. GET /. Now the certificate used also has ‘CN=www.google.com’. In which case there wont be any problem. All checks out, no certificate error.
Now the second site hosted in a different virtual host, provided by the same Apache instance is called using the http request header: logon.google.com. GET /. Now all hell breaks loose because our certificate still contains ‘CN=www.google.com’. The name doesnt match, and a certificate error is risen.
the reason for this is that SSL is actually being implemented by Apache, but prior to the actual request being send. There is no mechanism in place to determine the correct certificate, containing the correct CN prior to the http call.
When you are using multiple subdomains behind the same top level domain, for instance: http://www.mysite.com, service.mysite.com, mail.mysite.com. The solution might be to use a so called ‘wildcard’ certificate. This certificates CN name looks like: CN=*.mysite.com and will match correctly against all the subdomains.
When you are using mutiple top level domain sitesnames like: http://www.google.com, http://www.mysite.com, implementing SNI might be a solution. Be warned, SNI has a limited backwards compatibility. The client needs to support SNI to work property.
You could use multiple ports on the server and SSL on the various ports. This will require your visitors to add a port to the url like: https://www.google.com (default 443), https://www.mysite.com:445 (non default).
Alternativly use multiple IPs to bind the ssl. This will enable you to keep the default port 443. Requesting mulitple public IPs to do so might be costly, but is the most elegant solution (next to SNI).
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Biologists at the TU Darmstadt and ETH Zurich have developed a new concept for conservation measures that incorporates current landscapes formerly considered ecologically “of little value”. Numerous experiences from islands have shown that this concept has a positive effect on biodiversity. Now the authors are proposing upscaling these experiences to other landscape scenarios.
In a human-dominated world that contains only little “historical” nature, the term ecosystem can no longer be a synonym for unspoilt nature. The term “novel ecosystems” was coined a few years ago to describe disturbed ecosystems in which biodiversity has been significantly altered as the result of human intervention. “In our new conservation framework we argue that this strict distinction between historic and novel ecosystems should be reconsidered to aid conservation”, pollination biologist Dr. Christopher Kaiser-Bunbury describes the approach, which is not without controversy.
On continents with vast natural parks, such as the USA and Africa, critics fear that the new concept could weaken the protection of historic nature by, for instance, redirecting financial resources towards more active intervention and design of ecosystems. The team of Darmstadt and Zurich biologists, however, propagates a reconciling approach. “Our framework combines strategies that were, until now, considered incompatible. Not only historic wildlands are worth protecting, but also designed cultural landscapes. Given the increased anthropogenic pressure on nature, we propose a multi-facetted approach to preserve biodiversity: to protect historic nature where ecologically viable; to actively create new, intensively managed ecosystems; to accept novel ecosystems as natural, wild landscapes; and to convert agricultural and other cultivated landscapes while generally maintaining land-use priorities.”
Agricultural landscapes “of little value” belong on the agenda
New ecosystems may also include maize fields and banana plantations, as agricultural land can be used to preserve biodiversity. In fact, necessary measures are relatively easy to implement and comparatively inexpensive. Trials in Europe involving hedges and meadow strips along fields, for example, have shown that many animal species use these areas for feeding and nesting. Such modifications also create corridors between habitats that are traditionally worth protecting. “The individual measures proposed here are not novel but what is needed is an overall concept that combines these measures on a landscape level. And this is something that has been tested on many oceanic islands – with considerable success.”
Lessons from islands
The studies by the Darmstadt and Swiss biologists have shown that biodiversity conservation on regionally heterogeneous islands, such as Galapagos, Hawaii, Fiji or Seychelles, illustrates the successful implementation of such an integrated concept. On the Seychelles, for instance, the combined conservation measures include the strict protection of natural cloud forest on a few mountain tops, the management of abandoned cinnamon plantations, and green urban areas such as gardens. The recovery of threatened species and a halt to the decline of native biodiversity are indicators of the success of these conservation strategies. “At the same time, though, we need to know more about how invasive species influence biodiversity,” adds Professor Nico Blüthgen in the light of current investigations by the TU Darmstadt. “For example, native plants on Hawaii have not developed a protective mechanism against immigrant ants and are therefore threatened by their invasion.” His working group addresses the consequences of species extinction on ecosystem functioning.
In another study the ecologists aim to investigate how the concept developed on islands can bet intensively tested in different landscape settings, including on a larger scale on continents.Article:
Jörg Feuck | idw
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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The short and unpredictable nature of the conventional chemical batteries, along with the frequent replacements that they require, has created an acute need for a reliable, longer-lasting and rugged source of energy. Moreover Radars, spacecrafts, interstellar probes and other advanced communication devices require much larger power than that can be met by conventional energy sources. The solution to long term energy source is the nuclear powered batteries which have a life span of few decades and can pack in energy densities thousands of time greater than conventional battery sources. Hence, there is an urgent need to harvest enormous amount of energy released naturally by the tiny bits of radioactive material. Unlike conventional nuclear power generating devices, these batteries do not rely on the fission or fusion reactions and do not generate any radioactive material as by-product. They promise clean, safe, reliable and almost endless energy without any drop in its yield or efficiency during its entire life span-which runs up to minimum of 10 years. They are generally used as power sources in unmanned and unmaintained locations requiring energy for longer durations. Nuclear batteries are not only going to replace conventional batteries, chargers and adapters but also present innovative means of powering portable devices. The nuclear battery technology is geared up to make way into commonly used day to day product like cell phones, laptops, automobiles etc. Surely it is battery of future.
In this day and age of miniaturization the size of electronic circuitry has been diminishing at a astonishingly dizzying pace but the batteries that power these devices are not keeping up with them. The world of tomorrow that the technology manifests will be a very small one and we will need smaller batteries to power it !! Be it our personal laptops or cell phones, batteries still occupy a significant portion of the volume. The reason being the batteries are still nothing more than cans of chemicals like they were two centuries ago. They have not undergone any significant change in their functionality since Italian physicist Alexandaro Volta demonstrated flow of electric current between two conductors by alternating discs of zinc and copper with pieces of cardboard soaked in brine.
Many systems ideally (especially those in remote locations) have to operate for long periods, and it is not always feasible to recharge or replace their batteries. Now, with technology ushering in new era of miniaturization where MEMS (Micro Electrical Mechanical System) are gaining widespread popularity and are increasingly being used for a multitude of applications, they lack a durable onboard power supply. Batteries are at a critical juncture here!!
MEMS are finding increasing applications in everything from sensors in car that trigger an alarm to injectible drug delivery system to environment monitoring ‘Smart Dust’ but they lack a long lasting on-device power source. To work around this power block, researchers have found an intriguing way: by harvesting the huge amount of energy released by radioactive material. Although several sources of energy could be used to supply this needed power (solid, fossil fuel) by these MEMS based systems but nuclear batteries are fast becoming a popular option in terms of power density and lifetime.For example A tiny speck of radioisotope like nickel-63 can generate enough energy to power these MEMS for decades. These nuclear micro batteries have energy at densities at thousand times greater than the Lithium ion batteries. So with these miniature machines really hitting their stride, we’ll need smaller, reliable and longer lasting battery sources! To clear the common misconception, nuclear power sources are not miniature nuclear reactors and they do not involve any fission or fusion reactions. In these power sources we use specific isotopes which emit particles that are blocked by...
References: 1. “Nuclear and Radiochemistry” , Gerhardt Friedlander and Joseph W. Kennedy
Please join StudyMode to read the full document | <urn:uuid:341ed009-9275-46e3-968c-d7bc94afc785> | 3.484375 | 761 | Truncated | Science & Tech. | 23.201469 | 95,492,663 |
Authors: George Rajna
Weakly-interacting sparticles are produced at lower rates and lead to less striking signatures, making them more difficult to distinguish from Standard Model background processes. Supersymmetry (SUSY) is one of the most attractive theories extending the Standard Model of particle physics. If researchers at Florida Institute of Technology, employing pioneering new methods, are able to determine the top quark's mass at a level of precision as yet unachieved, they will move science closer to understanding whether the universe is stable, as we have long believed to be the case, or unstable. Last February, scientists made the groundbreaking discovery of gravitational waves produced by two colliding black holes. Now researchers are expecting to detect similar gravitational wave signals in the near future from collisions involving neutron stars—for example, the merging of two neutron stars to form a black hole, or the merging of a neutron star and a black hole. In a new study published in EPJ A, Susanna Liebig from Forschungszentrum Jülich, Germany, and colleagues propose a new approach to nuclear structure calculations. The results are freely available to the nuclear physicists' community so that other groups can perform their own nuclear structure calculations, even if they have only limited computational resources. The PHENIX detector at the Relativistic Heavy Ion Collider (RHIC), a particle accelerator at Brookhaven National Laboratory uniquely capable of measuring how a proton's internal building blocks — quarks and gluons — contribute to its overall intrinsic angular momentum, or "spin." More realistic versions of lattice QCD may lead to a better understanding of how quarks formed hadrons in the early Universe. The resolution of the Proton Radius Puzzle is the diffraction pattern, giving another wavelength in case of muonic hydrogen oscillation for the proton than it is in case of normal hydrogen because of the different mass rate. Taking into account the Planck Distribution Law of the electromagnetic oscillators, we can explain the electron/proton mass rate and the Weak and Strong Interactions. Lattice QCD gives the same results as the diffraction patterns of the electromagnetic oscillators, explaining the color confinement and the asymptotic freedom of the Strong Interactions.
Comments: 21 Pages.
[v1] 2017-05-18 10:44:33
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Research study provides new tools to assess warming temperatures
Spring is here and ectotherms, or animals dependent on external sources to raise their body temperature, are becoming more active. Recent studies have shown that as the average global temperature increases, some lizards may spend more time in the shade and less time eating and reproducing, which could endanger many species. Now, a detailed field study of the Puerto Rican crested anole by a University of Missouri researcher shows that lizards are active over a broader range of temperatures than scientists previously thought--but when temperatures are either too hot or too cold, critical activity levels slow, limiting the abilities of species to cope with climate variability.
Like other cold-blooded animals, lizards have preferred body temperatures at which they hunt, eat, move quickly and reproduce. The active range for Puerto Rican crested anole is between 81 and 84 degrees Fahrenheit (27-29 degrees Celsius). Scientists previously projected that the lizards would no longer be active at hotter or cooler temperatures. The MU study shows a different perspective.
"We found that lizards were most active between the temperatures previously reported; however, above and below that range, lizards were still active," said Manuel Leal, associate professor of biological sciences in the College of Arts and Science at MU. "Although climate change is still a major problem for lizards, our research indicates that their activity levels are less constrained by temperature than previously thought."
In the study, Leal and Alex Gunderson, a postdoctoral fellow at the University of California-Berkeley, conducted behavioral observations and collected temperature data on hundreds of crested anoles in their native tropical habitat in Puerto Rico. They recorded the lizards' movements and behaviors over 15-minute intervals and measured the lizards' body temperatures.
"The findings suggest that scientists need to rethink how to model the activity of ectotherms and how temperature rise due to climate change may affect behavior," Leal said. "Instead of treating activity as an on- or off-switch, we need to start thinking about activity as more of a dimmer switch, where behaviors are being dialed up and dialed down."
The new modeling techniques presented in the study should provide scientists with the tools they need to create more targeted ways of determining the effects of climate variability on lizards' activities, such as eating and reproducing, Leal said.
The study, "Patterns of Thermal Constraint on Ectotherm Activity," appears in the March 11 online issue of the journal American Naturalist.
Editor's Note: For more on the story, please see: http://biology.
Jeff Sossamon | 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....
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In many prokaryotes, noncoding RNAs that arise from the clustered regularly interspaced short palindromic repeat (CRISPR) loci are now thought to mediate defense against viruses and other molecular invaders by an RNAi-like pathway. CRISPR loci contain multiple short regions of similarity to invader sequences separated by short repeat sequences, and are associated with resistance to infection by corresponding viruses. It is hypothesized that RNAs derived from these regions, termed prokaryotic silencing (psi) RNAs, guide Slicer-like complexes of partner proteins to destroy invader nucleic acids. Here we have investigated CRISPR-derived RNAs in the archaeon Pyrococcus furiosus. Northern analysis revealed multiple RNA species consistent with a proposed biogenesis pathway that includes full-length CRISPR locus transcripts and intermediates generated by endonucleolytic cleavages within the repeat sequences. However, our results identify the principal products of the CRISPR loci as small psiRNAs comprised primarily of invader-targeting sequence with perhaps only 5-10 nucleotides of CRISPR repeat sequence. These RNAs are the most abundant CRISPR RNA species in P. furiosus and are likely the guides for the effector complexes of the proposed prokaryotic RNAi (pRNAi) system. We analyzed cell-free extracts fractionated under non-denaturing conditions and found that the various CRISPR RNA species are components of distinct RNA-protein complexes, including at least two complexes that contain mature-length psiRNAs. Finally, RNAs are produced from all seven CRISPR loci present in the P. furiosus genome, and interestingly, the most recently acquired psiRNAs encoded proximal to the leader sequence of a CRISPR locus appear to be the most abundant.
Mendeley saves you time finding and organizing research
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Soil properties differently influence estimates of soil CO2 efflux from three chamber-based measurement systems
Soil C02 efflux is a major component of net ecosystem productivity (NEP) of forest systems. Combining data from multiple researchers for larger-scale modeling and assessment will only be valid if their methodologies provide directly comparable results. We conducted a series of laboratory and field tests to assess the presence and magnitude of soil CO2 efflux measurement system x environment interactions. Laboratory comparisons were made with a dynamic, steady state C02 flux generation apparatus, wherein gas diffusion drove flux without creating pressure differentials through three artificial soil media of varying air-filled porosity. under these conditions, two closed systems (Li-6400-2009 and SRC-1) exhibited errors that were dependent on physical properties of the artificial media. The open system (ACES) underestimated C02 flux. However, unlike the two other systems. the ACES results could be corrected with a single calibration equation that was unaffected by physical differences in artificial media. Both scale and rank changes occurred among the measurement systems across four sites. Our work clearly shows that soil C02 efflux measurement system x environment interactions do occur and can substantially impact estimates of soil COz efflux. Until reliable calibration techniques are developed and applied, such interactions make direct comparison of published rates, and C budgets estimated using such rates, difficult.
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The danger from increasing levels of acid in the ocean, which could devastate California's shellfish industry, is under investigation by Bodega Bay scientists.
It is painstaking work that requires the team to wade through knee-deep mud at Tomales Bay to collect native Olympic oysters and then raise their young in salt-water tanks under conditions that mimic climate change.
"Very little is known about how ocean acidification is unfolding, other than it is," said Susan Williams, director of the Bodega Marine Laboratory, which is part of UC Davis. "We are already seeing dramatic effects."
The evidence is seen in the dissolving shells of some mollusks and disappearing mussel beds. And researchers, with the backing of more than $4 million in University of California and federal funds, are trying to identify the long-term consequences of the ocean's changing chemistry.
So far, the research has been limited to Olympia oysters, a native species that grows in the wild. But the conditions apply to other shellfish, such as abalone, clams, mussels and sea urchins.
Oysters are "the canary in the coal mine," said Brian Gaylord, a marine lab biologist.
The amount of carbon dioxide in the atmosphere has increased 30 percent in the past 150 years and, with climate change, is predicted to double in the next 100 years.
"What happens in the ocean mirrors what happens in the atmosphere," said Tessa Hill, an oceanographer and chemist at the lab.
The ocean absorbs the carbon dioxide and that changes the chemistry of the water to make it more acidic, which inhibits the ability of shellfish to form shells, Hill said.
The research involves collecting oysters in Tomales Bay, letting them spawn and then putting the larvae into conditions that introduce differing levels of carbon dioxide into the water. The juvenile oysters are then measured and studied.
The researchers also will launch buoys in the ocean off the Bodega Bay lab and in Tomales Bay to measure acid levels, temperatures and salinity.
So far what they have seen is a 40 percent reduction in shell size and a slower rate of respiration for juvenile oysters that are raised under conditions simulating the atmosphere of 2100, Gaylord said.
They still don't know whether shells are going to be weaker and thinner, making shellfish more vulnerable to predators, and whether the changes in ocean acidity will shorten their life spans or cause fewer to live past the larval stage.
"We don't know yet if the baby oysters have less chance of surviving. There may be more dying. This is what we will be looking at in the future," said Eric Sanford, a lab biologist.
The research began 18 months ago, and has been boosted by a a three-year, $600,000 grant from the National Science Foundation. The UC system has also given the lab, the Scripps Institution of Oceanography and UC Santa Barbara each $1.1 million for the research.
The Bodega Bay lab has received an additional $235,000 from the National Science Foundation to convert four rooms to sealed chambers in which the atmosphere can be controlled to imitate climate change.
Shellfish farms in California had $16.4 million in sales in the past fiscal year, according to the Pacific Shellfish Growers Association in Port Townsend, Wash.
Tod Friend, owner of the Tomales Bay Oyster Co., said the effects could be far-reaching.
Do not approach mountain lions. If you see one, do not run, crouch or turn your back. If necessary, make noise, try to look bigger by waving your arms or opening your jacket. Prevention is key, but if attacked, fight back.
Call 911 if there is an active threat.
Wildlife sightings can be reported to the Department of Fish and Wildlife by phone at 707-528-2002 or online at apps.wildlife.ca.gov/wir.
(California Department of Fish and Wildlife and National Parks Service) | <urn:uuid:314a9631-91e5-46e2-aab3-7f9c03a7abce> | 3.1875 | 832 | News Article | Science & Tech. | 52.135012 | 95,492,698 |
Fundamental sources of uranium and thorium
Global Distribution of Uranium and Thorium
The three quantitatively significant natural radioéléments are, in order of decreasing abundance, potassium, thorium, and uranium. All the isotopes of thorium and uranium are radioactive, but K40 (0.0118% of all K) is the only radioactive isotope of potassium. The true average and specific lithologie abundances of radioéléments throughout the earth may never be learned from direct measurement, but these elements have been measured extensively at the surface and interpreted for the interior from indirect evidence. The three sources of data are:
Chemical and radiometric analysis of meteorites interpreted to be representative of different earth layers;
Chemical and radiometric analysis of surficial rocks; and
Estimation of values for the earth’s interior from heat-flow and rock-conductivity data. | <urn:uuid:873fe382-11c5-4cb8-b81c-55079b449b0e> | 3.65625 | 185 | Knowledge Article | Science & Tech. | 5.875588 | 95,492,703 |
What reasons could there be for different water sample results at four sites along a river?
(See files attached with data).© BrainMass Inc. brainmass.com July 16, 2018, 12:53 pm ad1c9bdddf
In your data on water samples there are a number of parameters that have an effect on the quality of water used for human consumption. The pollution boards operated by various levels of governments monitor regularly the environment as a whole. When a river goes downstream it comes across with a number of activities which are both natural and man-made. For example if the river is passing through an area which is abundant in radioactive materials it will carry with it the useful and (also toxic) chemicals which have effect on the population living ...
Solution explains reasons for water samples being different at different areas of the same river in 385 words. | <urn:uuid:1bd0abac-1aa1-4671-b037-fbba1c01509a> | 3.28125 | 173 | Truncated | Science & Tech. | 52.260972 | 95,492,712 |
Petrology, Stratigraphy, And Geologic History Of Husband Hill, Gusev Crater, Mars
This is the first geologic field investigation of ancient, heavily cratered terrain on Mars: Husband Hill in Gusev Crater, as investigated by the Mars Exploration Rover (MER) Spirit, which explored this site from the ~150th through ~700th sols of her 90-sol mission (a sol is a martian day). This dissertation characterizes all of the rock classes that the rover encountered on Husband Hill and the West Spur, and presents a geologic map and cross-section. A microtextural analysis is presented, followed by descriptions of the occurrence, major element geochemistry, iron-bearing mineralogy, spectral characteristics, and origin of each rock class. The structure and stratigraphy of Husband Hill are investigated, using stereogrammetry applied to Pancam stereo image data. All potential bedding planes of all in-place outcrops are examined. A stratigraphic section is produced: the Peace Class unit onlaps the Watchtower Class unit. The Watchtower Class stratigraphic unit has a minimum thickness of 9 m, and can be correlated over a distance of ~200 meters. If this volcaniclastic material was emplaced conformably to the topography at the time of deposition, tens of meters of material may have been removed from Husband Hill. Variations within the Watchtower Class outcrops of Cumberland Ridge and the Husband Hill summit are analyzed. Subclasses, defined by previous workers on the basis of Mössbauerderived iron mineralogy, Pancam visible and near-infrared (VNIR) spectra, and Mini-TES thermal emission spectra are described, and a new set of subclasses, defined on the basis of microtexture, is presented. The size of knobby protuberances, quantifiable in Microscopic Imager (MI) data, is correlated with iron oxidation state and the abundance of nanophase and amorphous material. The variation across Watchtower Class targets may be due to gel weathering resulting from acid fog, with the degree of alteration varying inversely with the amount of insolation. In addition to the science, this dissertation presents detailed descriptions of the Mars Exploration Rover vehicle and all of its instruments and payload elements, including the physics behind each instrument; data analysis techniques, capabilities and limitations; and archived data products. Resources for finding MER data and the context of Spirit's mission are listed.
Mars, Mars Exploration Rover, Spirit; Columbia Hills, lithologies, alteration; Acid fog, gel weathering, microtexture
Jordan,Teresa Eileen; Lunine,Jonathan I.; Haynes,Martha Patricia
Ph.D. of Astronomy
Doctor of Philosophy
dissertation or thesis | <urn:uuid:e8501fe0-fe56-48be-8ca9-6e8d80ed124a> | 2.53125 | 579 | Academic Writing | Science & Tech. | 18.405647 | 95,492,713 |
Proteas are best known as the national symbol of South Africa. The international team behind today's new study created an evolutionary 'family tree' of all 2,000 protea plant species on Earth - the majority of which are found in South Western Australia (SWA) and the Cape Floristic Region (CFR) of South Africa. This 'family tree' enabled the researchers to examine how these and other regions of the planet with Mediterranean-style climates have become so-called 'biodiversity hotspots'.
Until now, scientists have not known exactly why such large numbers of plant and animal species live in these Mediterranean hotspots. They are places of significant conservational importance which, like the rainforests, contain some of the richest and most threatened communities of plant and animal life on Earth.
The research published today provides the first conclusive proof that plant species in two of these hotspots are evolving approximately three times faster than elsewhere on the planet. The study dates this surge in protea speciation as occurring in the last 10-20 million years, following a period of climate change during which SWA and the CFR became hotter, drier, and more prone to vegetation fires.
Dr Vincent Savolainen, a biologist based at Imperial College London and the Royal Botanic Gardens, Kew, one of the authors of the new study, explains its significance, saying:
"Something special is happening in these regions: new species of proteas are appearing notably faster than elsewhere, and we suspect this could be the same case with other plant species too. This study proves that the abundance of different kinds of proteas in these two areas isn't simply due to normal rates of species diversification occurring over a long period of time.
"This is the first step towards understanding why some parts of the planet with a Mediterranean-style climate have become species-rich biodiversity hotspots."
Dr Savolainen and his colleagues believe that climatic changes millions of years ago could be one of the factors that prompted the protea plants' 'hyperdiversification' in SWA and the CFR. As these two regions became hotter, dryer, and prone to seasonal fires, proteas - which are drought-resistant and able to re-grow easily after a fire - would have survived, thrived and diversified into new species when faced with less competition for resources from less hardy plants.
Dr Savolainen concludes: "South Western Australia and the Cape Floristic Region of South Africa are areas of great interest to both evolutionary biologists and conservationists, because they contain such a rich profusion of life but are under threat from mankind's activities.
"Understanding more about the evolutionary history of these biodiversity 'hotspots' is important because it can help make conservation efforts more efficient."
Proteas live in the southern hemisphere and come in many different shapes and sizes, from 35-metre-tall trees to low growing shrubs. All proteas have leathery leaves and cup-shaped groupings of small, brightly coloured flowers that resemble thistles.
The Cape Floristic Region of South Africa and South Western Australia are two of five areas on Earth with a Mediterranean-style climate which have been designated 'biodiversity hotspots' by Conservation International. The others are: central Chile, California, and the mediterranean basin.
Danielle Reeves | alfa
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:072ee5a1-be4f-4b73-aeb2-5507e124b35a> | 3.859375 | 1,343 | Content Listing | Science & Tech. | 35.877661 | 95,492,717 |
Fourier transform infrared (FTIR) spectroscopy is an information-rich method that reveals chemical bonding near the surface of polymer composites. FTIR can be used to verify composite composition, identify chemical contaminants and expose composite moisture content. Polymer matrix changes due to thermal exposure including loss of additives, chain scission, oxidation and changes in crystallinity may also be determined using FTIR spectra. Portable handheld instruments using non-contact reflectance or surface contact attenuated total reflectance (ATR) may be used for nondestructive evaluation (NDE) of thermal aging in polymer and composite materials of in-service components. We report the use of ATR FTIR to track oxidative thermal aging in ethylene-propylene rubber (EPR) and chlorinated polyethylene (CPE) materials used in medium voltage nuclear power plant electrical cable insulation and jacketing. Mechanical property changes of the EPR and CPE materials with thermal degradation for correlation with FTIR data are tracked using indenter modulus (IM) testing. IM is often used as a local NDE metric of cable jacket health. The FTIR-determined carbonyl index was found to increase with IM and may be a valuable NDE metric with advantages over IM for assessing cable remaining useful life.
Leonard S. Fifield, Yongsoon Shin, and Kevin L. Simmons, "Non-destructive evaluation of polyolefin thermal aging using infrared spectroscopy," Proc. SPIE 10169, Nondestructive Characterization and Monitoring of Advanced Materials, Aerospace, and Civil Infrastructure 2017, 101690U (Presented at SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring: March 27, 2017; Published: 19 April 2017); https://doi.org/10.1117/12.2261983.
Conference Presentations are recordings of oral presentations given at SPIE conferences and published as part of the conference proceedings. They include the speaker's narration along with a video recording of the presentation slides and animations. Many conference presentations also include full-text papers. Search and browse our growing collection of more than 12,000 conference presentations, including many plenary and keynote presentations. | <urn:uuid:28a613b8-e056-486f-b458-df483c3a12f5> | 2.59375 | 452 | Academic Writing | Science & Tech. | 17.498003 | 95,492,746 |
Scientists have uncovered evidence that shows a more complex and elaborate role for the body's hard-working G protein-coupled receptors (GPCRs) than previously thought, suggesting a conceptual advance in the fields of biochemistry and pharmacology. With more than 800 members in the human genome, GPCRs are the largest family of proteins involved in decoding signals as they come into the cell and then adapt the cell's function in response.
Manipulating how cells respond to signals is key to developing new medications. Although pharmacologists have studied GPCRs for many years, there is still a debate on how they operate -- are they isolated units that randomly collide with each other or are they deliberately coupled together to receive signals?
The scientists conclude that GPCRs form part of very elaborate pre-coupled macromolecular complexes. Simply put, they act as little computing devices that optimally gather and process information coming into the cell, allowing the cells to adapt and change their function.
"These findings represent many years of complex and highly nuanced science, following the trail as chemical signals travel through the body at the cellular level," said the senior author. "This remarkable discovery will open new avenues for medication development for addiction, pain and other conditions, offering more precise targets with fewer side effects."
To unravel the complex journey of the body's GPCRs, scientists used biophysical tools, including fluorescent biosensors; biochemical tools, such as cell signaling in neuronal cultures; as well as computational models.
Authors show the existence of functional pre-coupled complexes of heteromers of adenosine A2A receptor and dopamine D2 receptor homodimers coupled to their cognate Gs and Gi proteins and to subtype 5 AC. They also demonstrate that this macromolecular complex provides the necessary frame for the canonical Gs-Gi interactions at the AC level, sustaining the ability of a Gi-coupled GPCR to counteract AC activation mediated by a Gs-coupled GPCR.
"The specific macromolecular complex investigated in this study has therapeutic implications not only for addiction, but also for Parkinson's disease and schizophrenia," said the team lead. "Discovering that these protein interact with other signals in preformed complexes gives us more precise targets for medication development."
Pre-assembled GPCR macromolecular complex detected in cells
- 509 views | <urn:uuid:ea2460c7-6751-45d8-aa45-7083082358a1> | 3.25 | 492 | News Article | Science & Tech. | 16.904265 | 95,492,753 |
Please use this identifier to cite or link to this item:
Drilling at the Summit of Kilauea Volcano
|Title:||Drilling at the Summit of Kilauea Volcano|
|Authors:||Keller, George V.|
|LC Subject Headings:||Volcanoes--Hawaii|
Kilauea Volcano (Hawaii)
|Publisher:||Golden, CO: Colorado School of Mines|
|Citation:||Keller GV. 1974. Drilling at the summit of Kilauea Volcano. Golden (CO): Colorado School of Mines.|
|Abstract:||A borehole has been drilled to a depth of 1262 m beneath the summit of Kilauea Volcano on the island of Hawaii. The purposes were twofold: to obtain engineering information related to the possible occurrence of geothermal energy in a basaltic volcano, and to obtain scientific information about the internal nature and workings of Kilauea Volcano. Because the location of the borehole is within Hawaii Volcanoes National Park, the drilling could not have as its objective the production of steam. Accordingly, the drilling program was carried out in a manner intended to minimize the chance of a steam eruption, and to maximize the chances of gathering scientific information. The fact that the borehole was drilled without encountering any significant difficulties is in itself a measure of success. It was found that the interior of the volcano was not nearly as inhospitable an environment as some people anticipated. In fact, the only difficulties met in drilling were related to the remoteness of the location from normal sources of supply. Although there are numerous occurrences of very hot surface rocks close around the drillsite, the borehole penetrated only cool rocks until the water table was entered, at a depth of 490 meters. From this level to nearly sea level, at a depth of 1102 meters, a complicated temperature profile was observed, with temperatures varying between 60°C and 90°C. The groundwater in this zone appears to have a salinity roughly equal to that of sea water. It is thought that a convection system exists over this interval. At greater depths, the permeability of the rock is markedly reduced, though the porosity and water content remain high, in the range from 20 to 25 percent. The bottom-hole temperature is 137°C, and the gradient over the last hundred meters of hole is about 400°C per kilometer. If the hole were located in an area where production of geothermal energy could be undertaken, it is possible that production of commercial-quality steam could be obtained by drilling to depths 200 to 300 meters below the present depth. The major question that would have to be answered if steam production were sought would be whether or not permeability exists or could be induced in rocks at these depths.|
|Sponsor:||Prepared for National Science Foundation.|
|Appears in Collections:||The Geothermal Collection|
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