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COLD FUSION NOW!
what the differents this energy from the others energy ?
Cold fusion has a high energy density so tiny reactors can be made that last a really long time.
The reaction is clean, with no radioactive waste and no CO2 emissions.
The fuel is hydrogen, which is found in water, and abundant on Earth and in the universe.
It is different than any other energy source humans have ever had. When technology is available, cold fusion will revolutionize the world in ways we can’t even imagine.
yes and all of that have consequence.
one is that the autonomy may be huge, like nuclear reactor.
one is that it can be small, and managed by non professional like fire
one is that it produce heat and can use well known heat to power engines (turbines, stirlings…)
it is nuclear for everybody as people were dreaming in the 50s… until we realized it was too radioactive, and too heavy for most applications.
the density of energy is huge (like uranium – 10-100MW.h per gram), even if today the density of power is like a gas burner (1-10kW/kg).
this mean nuclear energy at home, plane flying for months, cars filled for decades, boats and plane lighters, island and lost villaged fueled once a decade…
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A Quick Guide to the Astronomy Site
What are other people reading? Where can I find an astronomy word search? I'd like some help to start observing. What is a meteor shower? Here is a guide to help you find what you want and get the best out of the BellaOnline Astronomy site.
ABC of Astronomy – A Is for Astronomy
In the ABC of astronomy, astronomy itself is the first and most important item. What is astronomy and how does it differ from astrology? What are the main specialist areas in astronomy and how do they contribute to the overall picture?
ABC of Astronomy – B Is for Bok Globule
B is for Bok globule, a kind of dark nebula studied by Bart Bok. B is for Bayer who invented a handy system of star designations beginning with a Greek letter. And B is for Baily's beads. You won't find them in a jewelry shop, but you might see them in a solar eclipse, as Francis Baily did.
ABC of Astronomy – C Is for Cosmic Rays
Hundreds of cosmic rays zip through your body every minute. They're a danger to astronauts, and may damage the electronics of satellites and spacecraft. Some aren't cosmic, none are rays, and a few seem to be impossible. What are they and where do they come from?
ABC of Astronomy – D Is for Double Star
We´re used to having just one Sun, so the planet Tatooine in George Lucas´s Star Wars seems exotic with its double sun. Yet at least half the stars we can see in the sky are doubles. But a "double star" can be a true binary or just an optical double, which is a chance alignment of unrelated stars.
Google doodles are little drawings and animations that incorporate the Google name into a presentation of a person or event of note. Here are five doodles with an astronomy theme, including asteroids, a lunar eclipse and how the speed of light was calculated by observing Jupiter and Io.
Here’s a collection of astronomy jokes for kids, adults and geeks of all ages. Laughter helps to keep us young and healthy, so see if anything tickles your fancy. (And how *does* the Man in the Moon cut his hair?)
Celestial Sleuth – book review
A "celestial sleuth" solves puzzles in art, history and literature using astronomy. Why did Munch have a blood-red sky in "The Scream"? How did British sentries miss Paul Revere rowing across Boston Harbour under a full Moon? Which meteor shower did the characters in James Joyce's "Ulysses" see?
Citizen Science in the Electronic Age
How many, and what kinds of birds are there around? How do we classify a million galaxies in sky survey images? How dark is the sky? Citizen scientists help to find out all of these things - and more. You could be a citizen scientist too.
We no longer see the heavens as perfect and the stars as eternal and unchanging. Even the Universe had a beginning, and everything that we observe changes and evolves. Many of these changes involve cosmic collisions.
Horses galloping and flying; creatures half human, half horse; dark horses invisible but for their silhouettes against the stars behind them. Find out about the cosmic equines that are features of our skies.
Distances in Space
You wouldn´t want to know the distance from Boston to San Francisco in inches. And for the same reason, miles aren´t very useful in space. After all, it´s 26 trillion miles to the next nearest star. So how do astronomers deal with these enormous distances?
Five Astronomical Non-events 2016
The astronomical delights of 2016 are wonderful discoveries and beautiful heavenly events. Not so delightful are the flaky stories and shaky science and “intelligent aliens” as the answer to any mystery. Here's my selection of five such non-events from 2016.
Five Astronomy Non-events of 2017
The year 2017 was favored with dire predictions of destructive giant impacts, and the 15 days of darkness “forecast by NASA” was back again. Unusually, there was no sign of the “Mars will look as big as the full Moon” that's been a regular since 2003. But there's also a new non-event.
Four Big Astronomy Non-events of 2015
In 2015 we learned a lot about the Solar System and beyond. And the splendid sky events included a solar eclipse and two lunar eclipses. Yet, as ever, people on social media people who delight in disaster were declaring doom. Should we be apprehensive? Let's see.
Four Historic Eclipses
An empire lost, an empire saved, lives lost, lives saved. Read about some unexpected outcomes of solar and lunar eclipses.
Gravity - Cosmic Glue
Aristotle's perfect cosmos didn't need gravity to hold it together. However a system with planets orbiting the Sun called for an explanation. In the process, Newton was inspired by a falling apple, but Galileo's experiments with falling bodies didn't involve dropping them off the Tower of Pisa.
How to Tell a Planet from a UFO
Two English policemen chased a UFO through the Devon countryside. It was the planet Venus. A news reporter had quite a scoop when she found a UFO hovering over New York City. It was the planet Jupiter. Why are planets and stars often mistaken for spacecraft or aircraft?
Light pollution isn't just a problem for astronomers. It means the loss of an amenity for all of us now and the generations that follow. It affects the natural world, can ruin our health, wastes resources, and what's more, we're paying for it!
Light Pollution - Facts for Kids
Thieves are stealing something that belongs to you. It´s something you inherited from countless generations of your ancestors: a view of the night sky. The unnecessary lighting that hides it also damages wildlife, increases air pollution and can damage your health. What can we do?
Merlin´s Tour of the Universe - book review
Does the Earth really wobble on its axis? How does the Sun make its heat? What would happen if I fell into a black hole? If you want to know the answers to these and many other questions, this book is a good collection of the things that people have asked "Merlin."
NASA Helped Rescue Chilean Miners
In the Chilean winter of 2010 thirty-three miners were trapped half a mile below the surface. They were in a hostile environment, a confined space, reliant on supplies from outside - similar to the problems of a space mission. Find out how NASA's decades of experience helped the Chilean rescuers.
Night Sky Olympic Tribute
Planet Earth presents a grand international sporting spectacular every four years, the Olympic Games. Even if you're not fond of sports, it's a majestic pageant and a set of unfolding dramas that a scriptwriter couldn't hope to emulate. Here is my astronomical tribute to this magnificent saga.
Phantom Planets and Moons
Moons of Venus and Mercury? An unknown planet nearer the Sun than Mercury? Astronomers can misinterpret what they see, too. Happily, other observers, better instruments and new theoretical understandings can put it right. Here are some phantom objects that many astronomers once thought existed.
These articles contain a wide selection of astronomical information, but each is based around a seasonal or topical theme.
Sky of Grand Central Terminal – It´s Backwards
A splendid starry sky crowns the concourse of Manhattan´s Grand Central Terminal. It´s a 1940s reworking of the original that Paul César Helleu designed after consultation with a prominent astronomer. Yet a month after the station opened, a starwise commuter claimed that the sky was backwards.
Star-gazing – Seeing in Dim Light
How can you see an object by not looking at it? Why do aurorae and deep-sky objects tend to look grey? How can an eyepatch and a red flashlight be useful to an astronomer? Why can a camera flash ruin a night's observing? Answers to all these questions are related to the way our eyes react to light.
Syzygy - When Heavenly Bodies Align
Syzygy may look like the letters on a dreadful Scrabble rack, but it just means three heavenly bodies lined up. When this happens, there are eclipses, transits, conjunctions, oppositions and occultations.
Tales of the Northern Lights
The aurora is an ethereal, shifting light in the northern sky and is associated with many tales and beliefs. It can look like the dawn, so Galileo named it after Aurora goddess of the dawn. It has reminded others of dragons, spirits, dancers, shield maidens, herrings or the legendary fire fox.
The Bluffer´s Guide to the Cosmos - book review
Here is an entertaining overview of astronomy small enough to put in your pocket. Not only the Big Bang, black holes, exploding stars, visiting Mars and all the rest of the cosmos, but plenty of laughs along the way. I enjoyed it - you must know someone who would too.
Top Astronomy Stories 2012
What were the big astronomy stories of the year 2012? Here is my choice of the top ten plus a non-story. What do you think?
Top Five Dubious Astronomy Stories 2014
Have you read about the Top Ten Astronomy Stories for 2014? This article is complementary to it. Here are my choices for the top five debatable stories of the year. They were widely reported, but there isn't really enough evidence to accept their conclusions.
Top Ten Astronomy Stories 2013
What were the big astronomy events of 2013? Here are my top ten choices and they include a big bang over Russia, a Moon goddess and Jade Rabbit, a telescope in the high Andean desert to look for the first galaxies, and the launch one of the most ambitious space missions ever.
Top Ten Astronomy Stories 2014
What happened in the skies in 2014? Here's my top ten. Some hints: it takes in stories all the way from a tiny lander alone on a comet to a supercluster of galaxies 500 million light years across, perhaps another Earth, and an ocean on one of Saturn's moons.
Top Ten Astronomy Stories 2015
Some called 2015 "The Year of the Dwarf Planet" because space missions visited both Pluto and Ceres. Elsewhere Philae briefly awoke on a comet. Water was found on Mars, and so was Beagle 2. But how did astronomers predict a supernova, and what is the most distant known object in the Solar System?
Top Ten Astronomy Stories 2016
Nothing in astronomy in 2016 topped the February announcement that the LIGO collaboration had finally detected gravitational waves, ripples in space-time predicted by Einstein. However this wasn't the only story in astronomy for 2016, and they range from the Solar System to a distant supercluster.
Top Ten Astronomy Stories 2017
2017 was an exciting one for astronomy, full of interesting events and discoveries. There was a fantastic solar eclipse that swept across North America, a star system with 7 Earth-sized planets, a quasar from the early Universe, Cassini's Grand Finale, a dwarf planet with rings, and much more.
What's in a Name
Things aren't always what they seem. Many discoveries aren't named for - or by - their discoverers. Halley didn't discover Comet Halley. Kuiper said the Kuiper Belt didn't exist. The Herschels called Uranus "the Georgian planet" after George III of England, but no one else did.
Who Let the Dogs out?
Someone must have left the door open, because the skies are full of dogs. You can see the dogs of Orion and the hunting dogs of the shepherd Bootes in pursuit of the Great Bear. There is also the Running Dog Nebula and the memory of poor Laika, the first cosmonaut, who perished in space.
Top Ten Articles
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Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies as high as 300 gigahertz (GHz) to as low as 30 hertz (Hz). At 300 GHz, the corresponding wavelength is 1 mm, and at 30 Hz is 10,000 km. Like all other electromagnetic waves, radio waves travel at the speed of light. They are generated by electric charges undergoing acceleration, such as time varying electric currents. Naturally occurring radio waves are emitted by lightning and astronomical objects.
Radio waves are generated artificially by transmitters and received by radio receivers, using antennas. Radio waves are very widely used in modern technology for fixed and mobile radio communication, broadcasting, radar and other navigation systems, communications satellites, wireless computer networks and many other applications. Different frequencies of radio waves have different propagation characteristics in the Earth's atmosphere; long waves can diffract around obstacles like mountains and follow the contour of the earth (ground waves), shorter waves can reflect off the ionosphere and return to earth beyond the horizon (skywaves), while much shorter wavelengths bend or diffract very little and travel on a line of sight, so their propagation distances are limited to the visual horizon.
To prevent interference between different users, the artificial generation and use of radio waves is strictly regulated by law, coordinated by an international body called the International Telecommunications Union (ITU), which defines radio waves as "electromagnetic waves of frequencies arbitrarily lower than 3 000 GHz, propagated in space without artificial guide". The radio spectrum is divided into a number of radio bands on the basis of frequency, allocated to different uses.
Discovery and exploitationEdit
Radio waves were first predicted by mathematical work done in 1867 by Scottish mathematical physicist James Clerk Maxwell. Maxwell noticed wavelike properties of light and similarities in electrical and magnetic observations. His mathematical theory, now called Maxwell's equations, described light waves and radio waves as waves of electromagnetism that travel in space, radiated by a charged particle as it undergoes acceleration. In 1887, Heinrich Hertz demonstrated the reality of Maxwell's electromagnetic waves by experimentally generating radio waves in his laboratory, showing that they exhibited the same wave properties as light: standing waves, refraction, diffraction, and polarization. Radio waves, originally called "Hertzian waves", were first used for communication in the mid 1890s by Guglielmo Marconi, who developed the first practical radio transmitters and receivers. The modern term "radio wave" replaced the original name "Hertzian wave" around 1912.
Speed, wavelength, and frequencyEdit
Radio waves in vacuum travel at the speed of light. When passing through a material medium, they are slowed according to that object's permeability and permittivity. Air is thin enough that in the Earth's atmosphere radio waves travel very close to the speed of light.
The wavelength is the distance from one peak of the wave's electric field (wave's peak/crest) to the next, and is inversely proportional to the frequency of the wave. The distance a radio wave travels in one second, in a vacuum, is 299,792,458 meters (983,571,056 ft) which is the wavelength of a 1 hertz radio signal. A 1 megahertz radio signal has a wavelength of 299.8 meters (984 ft).
The study of radio propagation, how radio waves move in free space and over the surface of the Earth, is vitally important in the design of practical radio systems. Radio waves passing through different environments experience reflection, refraction, polarization, diffraction, and absorption. Different frequencies experience different combinations of these phenomena in the Earth's atmosphere, making certain radio bands more useful for specific purposes than others. Practical radio systems mainly use three different techniques of radio propagation to communicate:
- Line of sight: This refers to radio waves that travel in a straight line from the transmitting antenna to the receiving antenna. It does not necessarily require a cleared sight path; at lower frequencies radio waves can pass through buildings, foliage and other obstructions. This is the only method of propagation possible at frequencies above 30 MHz. On the surface of the Earth, line of sight propagation is limited by the visual horizon to about 64 km (40 mi). This is the method used by cell phones, FM and television broadcasting and radar. By using dish antennas to transmit beams of microwaves, point-to-point microwave relay links transmit telephone and television signals over long distances up to the visual horizon. Ground stations can communicate with satellites and spacecraft billions of miles from Earth.
- Indirect propagation: Radio waves can reach points beyond the line-of-sight by diffraction and reflection. Diffraction allows a radio wave to bend around obstructions such as a building edge, a vehicle, or a turn in a hall. Radio waves also reflect from surfaces such as walls, floors, ceilings, vehicles and the ground. These propagation methods occur in short range radio communication systems such as cell phones, cordless phones, walkie-talkies, and wireless networks. A drawback of this mode is multipath propagation, in which radio waves travel from the transmitting to the receiving antenna via multiple paths. The waves interfere, often causing fading and other reception problems.
- Ground waves: At lower frequencies below 2 MHz, in the medium wave and longwave bands, due to diffraction vertically polarized radio waves can bend over hills and mountains, and propagate beyond the horizon, traveling as surface waves which follow the contour of the Earth. This allows mediumwave and longwave broadcasting stations to have coverage areas beyond the horizon, out to hundreds of miles. As the frequency drops, the losses decrease and the achievable range increases. Military very low frequency (VLF) and extremely low frequency (ELF) communication systems can communicate over most of the Earth, and with submarines hundreds of feet underwater.
- Skywaves: At medium wave and shortwave wavelengths, radio waves reflect off conductive layers of charged particles (ions) in a part of the atmosphere called the ionosphere. So radio waves directed at an angle into the sky can return to Earth beyond the horizon; this is called "skip" or "skywave" propagation. By using multiple skips communication at intercontinental distances can be achieved. Skywave propagation is variable and dependent on atmospheric conditions; it is most reliable at night and in the winter. Widely used during the first half of the 20th century, due to its unreliability skywave communication has mostly been abandoned. Remaining uses are by military over-the-horizon (OTH) radar systems, by some automated systems, by radio amateurs, and by shortwave broadcasting stations to broadcast to other countries.
In radio communication systems, information is carried across space using radio waves. At the sending end, the information to be sent, in the form of a time-varying electrical signal, is applied to a radio transmitter. The information signal can be an audio signal representing sound from a microphone, a video signal representing moving images from a video camera, or a digital signal representing data from a computer. In the transmitter, an electronic oscillator generates an alternating current oscillating at a radio frequency, called the carrier because it serves to "carry" the information through the air. The information signal is used to modulate the carrier, altering some aspect of it, "piggybacking" the information on the carrier. The modulated carrier is amplified and applied to an antenna. The oscillating current pushes the electrons in the antenna back and forth, creating oscillating electric and magnetic fields, which radiate the energy away from the antenna as radio waves. The radio waves carry the information to the receiver location.
At the receiver, the oscillating electric and magnetic fields of the incoming radio wave push the electrons in the receiving antenna back and forth, creating a tiny oscillating voltage which is a weaker replica of the current in the transmitting antenna. This voltage is applied to the radio receiver, which extracts the information signal. The receiver first uses a bandpass filter to separate the desired radio station's radio signal from all the other radio signals picked up by the antenna, then amplifies the signal so it is stronger, then finally extracts the information-bearing modulation signal in a demodulator. The recovered signal is sent to a loudspeaker or earphone to produce sound, or a television display screen to produce a visible image, or other devices. A digital data signal is applied to a computer or microprocessor, which interacts with a human user.
The radio waves from many transmitters pass through the air simultaneously without interfering with each other. They can be separated in the receiver because each transmitter's radio waves oscillate at a different rate, in other words each transmitter has a different frequency, measured in kilohertz (kHz), megahertz (MHz) or gigahertz (GHz). The bandpass filter in the receiver consists of a tuned circuit which acts like a resonator, similarly to a tuning fork. It has a natural resonant frequency at which it oscillates. The resonant frequency is set equal to the frequency of the desired radio station. The oscillating radio signal from the desired station causes the tuned circuit to oscillate in sympathy, and it passes the signal on to the rest of the receiver. Radio signals at other frequencies are blocked by the tuned circuit and not passed on.
Biological and environmental effectsEdit
Radio waves are nonionizing radiation, which means they do not have enough energy to separate electrons from atoms or molecules, ionizing them, or break chemical bonds, causing chemical reactions or DNA damage. The main effect of absorption of radio waves by materials is to heat them, similarly to the infrared waves radiated by sources of heat such as a space heater or wood fire. The oscillating electric field of the wave causes polar molecules to vibrate back and forth, increasing the temperature; this is how a microwave oven cooks food. However, unlike infrared waves, which are mainly absorbed at the surface of objects and cause surface heating, radio waves are able to penetrate the surface and deposit their energy inside materials and biological tissues. The depth to which radio waves penetrate decreases with their frequency, and also depends on the material's resistivity and permittivity; it is given by a parameter called the skin depth of the material, which is the depth within which 63% of the energy is deposited. For example, the 2.45 GHz radio waves (microwaves) in a microwave oven penetrate most foods approximately 2.5 to 3.8 cm (1 to 1.5 inches). Radio waves have been applied to the body for 100 years in the medical therapy of diathermy for deep heating of body tissue, to promote increased blood flow and healing. More recently they have been used to create higher temperatures in hyperthermia treatment, to kill cancer cells. Looking into a source of radio waves at close range, such as the waveguide of a working radio transmitter, can cause damage to the lens of the eye by heating. A strong enough beam of radio waves can penetrate the eye and heat the lens enough to cause cataracts.
Since the heating effect is in principle no different from other sources of heat, most research into possible health hazards of exposure to radio waves has focused on "nonthermal" effects; whether radio waves have any effect on tissues besides that caused by heating. Electromagnetic radiation has been classified by the International Agency for Research on Cancer (IARC) as "Possibly carcinogenic to humans". The conceivable evidence of cancer risk via Personal exposure to RF-EMF with mobile telephone use was identified.
Radio waves can be shielded against by a conductive metal sheet or screen, an enclosure of sheet or screen is called a Faraday cage. A metal screen shields against radio waves as well as a solid sheet as long as the holes in the screen are smaller than about 1/20 of wavelength of the waves.
Since radio frequency radiation has both an electric and a magnetic component, it is often convenient to express intensity of radiation field in terms of units specific to each component. The unit volts per meter (V/m) is used for the electric component, and the unit amperes per meter (A/m) is used for the magnetic component. One can speak of an electromagnetic field, and these units are used to provide information about the levels of electric and magnetic field strength at a measurement location.
Another commonly used unit for characterizing an RF electromagnetic field is power density. Power density is most accurately used when the point of measurement is far enough away from the RF emitter to be located in what is referred to as the far field zone of the radiation pattern. In closer proximity to the transmitter, i.e., in the "near field" zone, the physical relationships between the electric and magnetic components of the field can be complex, and it is best to use the field strength units discussed above. Power density is measured in terms of power per unit area, for example, milliwatts per square centimeter (mW/cm²). When speaking of frequencies in the microwave range and higher, power density is usually used to express intensity since exposures that might occur would likely be in the far field zone.
- C. A. Altgelt, The World's Largest "Radio" Station
- Ellingson, Steven W. (2016). Radio Systems Engineering. Cambridge University Press. pp. 16–17. ISBN 1316785165.
- ITU Radio Regulations, Chapter I, Section I, General terms – Article 1.5, definition: radio waves or hertzian waves
- Harman, Peter Michael (1998). The natural philosophy of James Clerk Maxwell. Cambridge, England: Cambridge University Press. p. 6. ISBN 0-521-00585-X.
- "Heinrich Hertz: The Discovery of Radio Waves". Juliantrubin.com. Retrieved 2011-11-08.
- "22. Word Origins". earlyradiohistory.us.
- "FREQUENCY & WAVELENGTH CALCULATOR". www.1728.org. Retrieved 15 January 2018.
- "National Radio Astronomy Observatory - National Radio Astronomy Observatory". National Radio Astronomy Observatory. Retrieved 15 January 2018.
- Seybold, John S. (2005). Introduction to RF Propagation. John Wiley and Sons. pp. 3–10. ISBN 0471743682.
- Brain, Marshall (2000-12-07). "How Radio Works". HowStuffWorks.com. Retrieved 2009-09-11.
- Kitchen, Ronald (2001). RF and Microwave Radiation Safety Handbook. Newnes. pp. 64–65. ISBN 0750643552.
- VanderVorst, André; Rosen, Arye; Kotsuka, Youji (2006). RF / Microwave Interaction with Biological Tissues. John Wiley and Sons. pp. 121–122. ISBN 0471752045.
- Graf, Rudolf F.; Sheets, William (2001). Build Your Own Low-power Transmitters: Projects for the Electronics Experimenter. Newnes. p. 234. ISBN 0750672447.
- Elder, Joe Allen; Cahill, Daniel F. (1984). Biological Effects of Radiofrequency Radiation. US Environmental Protection Agency. pp. 5.116–5.119.
- Hitchcock, R. Timothy; Patterson, Robert M. (1995). Radio-Frequency and ELF Electromagnetic Energies: A Handbook for Health Professionals. John Wiley and Sons. pp. 177–179. ISBN 0471284548.
- http://www.iarc.fr/en/media-centre/pr/2011/pdfs/pr208_E.pdf and http://monographs.iarc.fr/ENG/Classification/index.php
- Gerke, Daryl (2018). Electromagnetic Compatibility in Medical Equipment: A Guide for Designers and Installers. Routledge. p. 6.67. ISBN 1351453378.
- Broadcasters, National Association of (1996). Antenna & Tower Regulation Handbook. NAB, Science and Technology Department. ISBN 9780893242367. Archived from the original on 2018-05-01.
- James Clerk Maxwell, "A Dynamical Theory of the Electromagnetic Field", Philosophical Transactions of the Royal Society of London 155, 459–512 (1865).
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- Karl Rawer: "Wave Propagation in the Ionosphere". Kluwer, Dordrecht 1993. ISBN 0-7923-0775-5 | <urn:uuid:5d036336-3b11-4323-934e-97cd8721b962> | 4.28125 | 3,472 | Knowledge Article | Science & Tech. | 40.541836 | 95,565,768 |
Organisms precisely regulate cell size to ensure that daughter cells have sufficient cellular material to thrive or to create specific cell types: a tiny sperm versus a gargantuan egg for example. In single-celled organisms such as yeast and bacteria, nutrient availability is the primary determinant of cell size. In animal cells, size is controlled in large part by a molecule that senses the blood sugar-dependent hormone insulin.
Petra Levin, Ph.D., Assistant Professor of Biology at Washington University in St. Louis, and her laboratory have recently identified a trio of enzymes that act in concert to link nutrient availability to cell size in the soil bacterium Bacillus subtilis.
Levin and her lab are looking into the factors that control the timing and position of cell division in B. subtilis. B. subtilis serves as the model system for a large family of bacteria that includes the causative agents of several important diseases, including anthrax and botulism. By learning how these simple organisms regulate division, she hopes to better understand why this process goes awry in cancer cells resulting in uncontrolled growth and aberrant division.
A primary focus of the Levin lab's research is a protein called FtsZ. FtsZ is an ancestor of tubulin, the protein that is responsible for distributing duplicated chromosomes between dividing human cells. In bacteria, FtsZ forms a ring at the future division site. The FtsZ ring then recruits all other components necessary for cell division and serves as the scaffolding for the entire division process.
The factors that regulate FtsZ ring formation determine when and where the cell is going to divide. "Theoretically a cell could divide anywhere and at anytime," said Brad Weart, a graduate student in Levin's lab. "The cell has to very precisely restrain that process so that it only happens when and where the cell wants it to happen."
In their most recent paper, published in the July 27, 2007 issue of Cell, Weart et al. identified a metabolic sensor that links cell division and cell size in B. subtilis with nutritional availability. This sensor is comprised of a three enzyme pathway that was previously shown to be involved in synthesizing a modified component of the cell membrane. The Levin lab's data indicates the pathway also has a major role in cell division. "So far this has been the only pathway that's been identified in bacteria that directly regulates cell size," says Levin.
Typically, cells in nutrient-rich environments grow bigger than cells in nutrient-poor environments. The Levin lab determined that mutations in genes encoding the three enzymes resulted in cells that were small even when they were in a nutrient-rich environment. "Basically, the cells had no way to tell the division apparatus to wait until they've reached the size they should be. The cells would divide when they were still very short," said Levin. "It was almost as if they were growing in really great media but they didn't know it."
Knowing when to divide
Further work indicated that the mutation perturbed FtsZ ring formation. In the cell, FtsZ exists in a balance between its unassembled and assembled state. The enzyme trio regulated FtsZ ring formation by changing this balance — pushing FtsZ towards its unassembled state when the cells were growing in nutrient-rich conditions, thereby delaying cell division and increasing cell size.
All three enzymes in the pathway are sensitive to glucose levels, and the pathway is therefore well suited to communicating nutritional information directly to the cell's division apparatus. In nutrient-poor conditions the enzymes no longer inhibit FtsZ assembly, allowing the FtsZ ring to form when the cells are still small, resulting in the formation of smaller daughter cells. The third enzyme in the pathway, UgtP, physically interacts with FtsZ to prevent ring formation. UgtP responds to low levels of glucose (nutrient-poor conditions) by becoming unstable and forming what appear to be inactive aggregates.
Disrupting this pathway leads to defects in chromosome segregation. A cell that is too small is unable to effectively move its DNA away from the division site and the resultant daughter cells frequently do not contain all the genetic material that they should. By coordinating cell size with growth rate, cells are able to maintain proper distribution of DNA.
This work is also something of a cautionary tale about the limitations of genome sequencing. "More and more often we are finding that metabolic enzymes have more than one function," said Levin, "There is no hint from their sequence that they have other activities so you really need to delve deeper and apply different methods to identify them."
Levin notes that her research is uncovering just the "tip of the iceberg" in the field of cell size control, but identifying genes such as ugtP helps Levin and other researchers get a better handle on precisely what determine how big a cell will be.
Tony Fitzpatrick | EurekAlert!
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Arctic sea ice increased by a third after an unusually cool summer in 2013, scientists have said, but it doesn't mean the fight against climate change is over.
Although the volume of ice continued increasing into 2014, and compensated for losses recorded in the three previous years, researchers say the growth is a one off.
"Between 2010 and 2012, there was a 14% reduction in Arctic sea ice volume, in keeping with the long-term decline in extent," the report, published in the Nature Geoscience journal, read. "However, we observe 33% and 25% more ice in autumn 2013 and 2014, respectively, relative to the 2010–2012 seasonal mean, which offset earlier losses."
The increase in ice was caused by the retention of thick sea ice northwest of Greenland, the report continues. A 5% drop in the number of days on which melting occurred, thanks to weather conditions akin to those of the 1990s, also contributed to the growth.
Rachel Tilling, Andy Ridout, Andrew Shepherd and Duncan Wingham, authors of the report, also noted the volume of springtime Arctic sea ice had remained stable.
— Rachel Tilling (@rachel_tilling) May 17, 2015ADVERTISEMENT
"The sharp increase in sea ice volume after just one cool summer suggests that Arctic sea ice may be more resilient than has been previously considered."
But the scientists say the data is a one-off, and climate change will continue to shrink Arctic ice in the coming decades. Since 1980, satellite observations have monitored a 40% decrease in the extent of sea ice cover in Arctic, the BBC notes.
Speaking to HuffPost UK, Rachel Tilling said the long-term trend in Arctic temperature is upwards, while sea ice volume is down.
"However, in all climate systems we’d expect to see some natural variability about this trend, which we believe was the case in 2013," she continued. "Unfortunately, I think the data will fuel climate change deniers' arguments that the world isn't warming up.
"But this is not the case. As I mentioned above, the long-term trend in Arctic temperature is upwards and in sea ice volume is downwards. 2013 was simply an anomalous year.
"The jump in the amount of sea ice in 2013 wound back the clock a few years on the gradual decline that has happened over the past few decades. If somebody has predicted ice free conditions in the near future, then they should certainly reflect on what our measurements add to the picture. However, to reiterate, again, we do expect volume to decrease further if temperatures continue to increase."
The researchers added they believe sea ice is more sensitive to temperature changes than previously thought. Although this could signal a positive change for the Arctic during cooler conditions, it also means the ice will be less resilient during warmer temperatures.
Dr Benny Pieser, director of The Global Warming Policy Foundation, which aims to challenge "extremely damaging and harmful policies" around the effects of climate change, said the paper "doesn't change anything".
"We've been monitoring both Arctic and Antarctic ice caps for a long time, and the basic problem for everyone trying to understand what's going on is that our observational data only starts with the satellite age - so it goes back about 30 years," he told HuffPost UK.
"We don't fully know what the ice caps looked like 50 or 100 years ago, and therefore it is difficult to make long-term predictions.
"The melting of ice caps may be slower than thought, as there were predictions they'd be gone by now. Basically it all depends on what global temperatures are going to do in the coming decades. The good news about this study is it is not a one way street, there are periods where the ice can recover.
"I don't think one paper can tell you much, we know global temperature has more or less stalled over the past 10 to 15 years," he continued. "We are increasing CO2 emission at an accelerating rate but temperatures aren't rising as fast as predicted."
The findings were initially published in 2013, but have since been updated to include 2014 data. | <urn:uuid:1e63b5d4-b7bb-4f4b-a92d-5cbc1979e2f4> | 2.765625 | 844 | News Article | Science & Tech. | 45.526301 | 95,565,784 |
The new compound, soon to be tested in cells, binds tightly to its target, an abnormally elongated RNA that hijacks part of the normal cellular machinery and brings on symptoms of the disease. The newly developed compound is the first to show high selectivity in binding the target while not disrupting other important RNA functions. The study appears this week in the Proceedings of the National Academy of Sciences.
Myotonic dystrophy type 1, a muscle degeneration disease that so far is untreatable, affects about one in 8,000 people worldwide. Some cases are mild, but others lead to a debilitating loss of muscle control, declines in organ function and other potentially life-threatening conditions.
Scientists have recently identified a primary causative agent of the disease, a mutant version of a gene, called DMPK, which contains an excessive number of tri-nucleotide repeats. Nucleotides are the chemical letters that spell out the sequence of a gene, and the normal version of the DMPK gene includes five to 34 cytosine-thymine-guanine (CTG) repeats. The mutant version of the gene includes 50 to as many as 10,000 CTG repeats.
“The longer the repeat the worse the disease and the earlier the onset of the disease,” said U. of I. chemistry professor and department head Steven Zimmerman, who co-led the research with his colleague, chemistry professor Anne Baranger.
When the mutant DMPK is transcribed into RNA, the first step toward building a protein, these (now CUG) repeats bind to a cellular protein, MBNL, which normally splices other RNA transcripts. The bound MBNL cannot function properly, causing a cascade of negative effects in the cell. Improperly spliced RNAs lead to improperly formed proteins.
Preventing the MBNL protein from binding to the CUG repeats has been shown to ease the symptoms of the disease.
“The RNA is the primary target” for drug design, Zimmerman said. “It’s quite clear that if we can bind to the RNA and displace the protein, it’s very likely to relieve the symptoms.”
The CUG repeats in the aberrant RNA are an ideal target for drug development because they are not found in any other known RNA molecule, Baranger said.
“They don’t have a normal function, so it’s okay to bind to those repeats,” she said. “You certainly don’t want to target the protein because you want it to go perform its normal function.”
In the course of basic research into compounds that bind to DNA or RNA, the researchers designed a molecule that would selectively bind to T-T or U-U mismatches in DNA or RNA, respectively. (Mismatches occur when two nucleotides in a double-stranded molecule are improperly paired, as occurs in the CTG repeats in the mutant DNA and the CUG repeats in the RNA.) Their compound, which they call Ligand 1, binds to the region of excessive repeats in both the RNA and DNA from the aberrant DMPK gene. More importantly, Ligand 1 prevents the MBNL protein from binding to the RNA.
Further tests revealed that the new compound has significantly lower affinity for other mismatches in DNA or RNA. Baranger’s lab also tested the compound on other normal protein-RNA complexes, and found that it did not disrupt those interactions.
This last finding was critical, Zimmerman said.
“The danger is if you make something that binds to RNA or DNA, it’s going to bind to all these other molecules and disrupt those complexes, so you help one problem but you cause all these others. Our molecule doesn’t do that.”
Zimmerman and Baranger, with their colleague, chemistry professor Paul Hergenrother, are the recipients of a new five-year nearly $2 million grant from the National Institute of Arthritis and Musculoskeletal and Skin Diseases at the National Institutes of Health to pursue this research.
Diana Yates | University of Illinois
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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This is the Conclusions section of the paper "Heat-Induced Yellowing of TCF-Bleached Sulphite Pulps--Mechanistic Aspects and Factors that Influence the Process," originally published in the Journal of Pulp and Paper Science, 25(2):47-51, Feb. 1999. It is reproduced here with permission, as an example of the research on "color reversion" or darkening of paper with age or as a result of specific chemical interactions.
TCF means "totally chlorine-free." Sulphite pulp mills are common in Europe, but not in the U.S. The trend away from use of chlorine in bleaching of pulps has been fueled by serious environmental concerns.
The heat-induced yellowing of TCF bleached pulps is an extraordinarily complex process. A high number of interacting factors influence the brightness stability of the materials. The yellowing process proceeds predominantly in the carbohydrate part of the pulps. Oxidation processes seem to play a role in the formation of chromophores only in cases of relatively high lignin content. Except for the temperature, the most important factors are humidity and intrinsic pH of the pulps, indicating that the hydrolytic processes are mainly responsible for discoloration. The yellowing tendency of the pulp is stronger the higher the oxidation state of the carbohydrate matrix. During heating, the carbohydrates undergo reactions which lead to the formation of furan-type heteroaromatics. The formation of furan derivatives indicates that hemicelluloses may also be involved in these processes.
A weak influence of the carbonyl content on the brightness stability was found. Ketone and aldehyde groups could be analytically separated. Carboxyl groups act as proton donors which catalyze hydrolytic reactions and the dehydration of the carbohydrates, thus accelerating the formation of chromophores.
Heavy-metal ions seem to act in the same manner as carboxylic protons. They can be masked by complexing agents. In this case, yellowing is less marked.
These facts are like pieces of a puzzle ready to be assembled into a more complete picture of the yellowing process. Although the results of the experiments shown here support the mechanism proposed in this scheme, some of the pathways remain hypothetical. However, they seem quite plausible, and nevertheless, might serve as a starting point for further investigation.
Timestamp: Sunday, 03-Mar-2013 21:39:32 PST
Retrieved: Friday, 20-Jul-2018 15:59:23 GMT | <urn:uuid:556bfd2c-a369-4ffb-8f76-5596098c38c3> | 2.71875 | 524 | Academic Writing | Science & Tech. | 36.317803 | 95,565,792 |
Oil-eating robots and apartment-dwelling bees are only a couple of the tricks scientists and engineers are using to avoid the worst effects of climate change.
There are many other strategies, detailed in a laundry list of TED talks, that explore how humans can keep the planet healthy in the coming decades.
Here are some of the most thought-provoking.
“This computer will grow your food in the future” by Caleb Harper
As Caleb Harper tells it, fewer people are getting into the farming business each year, which could threaten global crop production. Harper, the director of MIT’s Open Agriculture Initiative, developed a solution that may simplify the food production process.
Harper’s food computer is a device that can monitor and regulate growing conditions for crops. It grows food indoors in tighly controlled environments, handling variables like humidity and mineral quantities automatically. The result is a near-perfect crop of vegetables on a small scale – think tiny beds of lettuce, broccoli, and tomatoes – and the potential for sustainability on a wide scale.
“4 ways we can avoid catastrophic drought” by David Sedlak
Sedlak, a civil and environmental engineer, looks at global warming and sees a need to protect the world’s water stores, which currently live in reservoirs and aquifers.
Sedlak believes we need smarter ways of capturing stormwater underground, before diverting it to nearby treatment plants. He also calls for recycling waste water to make it drinkable, or “potable.”
Preventing over-consumption is also vital, he says, namely through sensors that can monitor sprinkler and irrigation use.
“We need nuclear power to solve climate change” by Joe Lassiter
Lassiter, an energy expert, argues detaching from oil and natural gas should be a no-brainer if governments can properly harness the power of nuclear energy.
“We have not used our latest scientific thinking on radiological healthto think how we communicate with the publicand govern the testing of new nuclear reactors,” he said. “We have new scientific knowledge that we need to use in order to improve the way we regulate nuclear industry.”
“Buildings that blend nature and city” by Jeanne Gang
Population forecasts say 67% of people will live in cities by 2050. As an architect obsessed with nature, Gang approaches her work to create designs that cater to that cramped, crowded future.
Her talk showcases some of her past work, including a Chicago high-rise apartment building that promotes social interaction among its tenants and a social justice center that uses logs instead of bricks in construction (to avoid the carbon footprint brought on by burning that wood).
Her overall goal is to bring city-dwellers closer together while also protecting the planet.
“A small country with big ideas to get rid of fossil fuels” by Monica Araya
In Araya’s home country of Costa Rica, five renewable energy sources – hydropower, geothermal, wind, solar, and biomass – supply nearly 100% of the power.
The tiny nation of 5 million people is a case study in how to protect the environment and develop new sources of energy at the same time, Araya says.
Costa Rica is also experimenting with electric buses and plans to go totally renewable by 2025.
“How we’re growing baby corals to rebuild reefs” by Kristen Marhaver
Marhaver, a coral reef biologist, details how important the disappearing coral reefs are to both the environment and human well-being.
They protect shorelines from storm surge, act as natural water filters, and provide a home to molecules that further the study of antibiotics and cancer drugs.
Together with her colleagues, Marhaver has taken on the job of breeding coral populations and introducing them to natural environments, so that they (and we) can prosper.
“A robot that eats pollution” by Jonathan Rossiter
Engineer Jonathan Rossiter developed a robot that uses microbes placed inside in a fuel cell to chomp away at algae or crude oil and produce energy in the process. That energy can then be used to power the robot and clean up even more of the environment.
He calls it the “Row-bot.”
Right now the robots are made of plastic, but Rossiter hopes to fashion them out of biological materials someday so they can degrade once they complete their life cycle.
“Every city needs healthy honey bees” by Noah Wilson-Rich
Honey bee populations are vital for keeping plant ecosystems alive through cross-pollination, beekeeper Wilson-Rich explains. Pollinators support 70 of the top 100 food crops, or roughly 90% of the world’s nutrition.
As the world urbanizes, even cities have a need for beekeeping, Wilson-Rich says. City-dwellers people can “hide a hive inside your home” (ideally on the roof, if you’re in an apartment building) and paint it to your preferred aesthetic.
“We save on the costs of transportation,we save on a healthier diet, and we also educateand create new jobs locally,” he says. “We need bees for the future of our cities and urban living.” | <urn:uuid:576cd68e-82bd-4472-9dbb-86c14c118d69> | 3.140625 | 1,104 | Listicle | Science & Tech. | 37.327348 | 95,565,799 |
Of the estimated 10,000 to 100,000 microbial species that inhabit our planet, scientists can only coax a few thousand to grow in the laboratory. As a result, efforts to categorize the vast diversity of microbes are lagging far behind attempts to classify plants, animals and insects. Now a report published in the current issue of the journal Science suggests that some of these so-called uncultivable microorganisms might not be so out of reach after all.
Tammi Kaeberlein, Kim Lewis and Klava Epstein of Northeastern University succeeded in growing pure cultures of elusive beach-growing bacteria by recreating their shore environment in the lab. The scientists collected blocks of beach and separated the microorganisms that reside on the sandy surface into sealed chambers, which were then set atop the sediment blocks inside aquariums. Though chemicals and nutrients could enter the chambers, the bacteria remained trapped. The novel experimental set-up garnered a nearly 300 percent increase in the number of microorganisms that produced colonies as compared with results achieved in conventional petri dishes. Moreover, the team isolated two previously unknown microbes, dubbed MSC1 and MSC2, and is analyzing nine others.
MSC1 (see image) and MSC2 also provided clues as to why some microorganisms refuse to grow in a stark laboratory dish even when ample nutrients are provided. The researchers discovered that culturing MSC1 and MSC2 in the specially designed chambers was easy but the bacteria would only grow in a petri dish if both strains were present. Because bacteria can use chemicals known as pheromones to communicate, the authors conclude that "it seems possible that microorganisms require specific signals originating from their neighbors that indicate the presence of a familiar environment."
Sarah Graham | American Scientist
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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Since the computing revolution, modelling has become the most important way in which we further our knowledge about how the sea moves and how the processes in the sea operate. The coast and the continental shelf are two of the most important areas of the sea to understand. "Coastal and Shelf Sea Modelling" is therefore very timely and important. In this text, modelling the processes that occur in the sea is motivated continually through real life examples. Sometimes these are incorporated naturally within the text, but there are also a number of case studies taken from the recent research literature. These will be particularly valuable to students as they are presented in a style more readily accessible than that found in a typical research journal. The motivation for modelling is care for the environment.The well publicised problem of global warming, the phenomenon of El Nino, more localised pollution scares caused by tanker accidents and even smaller scale coastal erosion caused by storms all provide motivation for modelling and all get coverage in this text. Particularly novel features of the book include a systematic treatment of the modelling process in a marine context, the inclusion of diffusion in some detail, ecosystems modelling and a brief foray into wave prediction. The final chapter provides the reader with the opportunity to do some modelling; there are many worked examples followed by exercises that readers can try themselves. All answers are provided.Throughout, the style is informal and the technicalities in term of mathematics are kept to a minimum. "Coastal and Shelf Sea Modelling" is particularly suitable for graduate marine and oceanographic modelling courses, but will also prove useful to coastal engineers and students at any level interested in the quantitative modelling of marine processes. It is stressed that only a minimal level of mathematics (first year calculus or less) is required; the style and content is introductory.
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Nano Science and Nano Technology Comparison
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Whenever the topic nano technology comes up most of us don't have a clear idea of what it is. Especially when it is about the difference between nano science and nano technology. Then what is nano science?
Nanoscience is the study of objects with size less than hundred nanometers at least in one dimension. When objects go to nanometer scale in size, their behavior get changed applied laws may not be the same as when they were larger in size. Nanoscience involves finding governing laws of these tiny objects, deriving theoretical models to describe the behavior of those nanoscale materials and analyzing the properties of them.
So, what is Nano technology?
Nanotechnology is engineering the nanoscale objects at molecular level using different techniques. Nanotechnology is all about techniques and tools to come up with a nanoscale design or system that exploit the properties at molecular level to be more accurate and efficient.
Using the knowledge on material behaviour at nanoscale which is got from nanoscience, nanotechnology focuses on properties such as strength, lightness, electrical and thermal conductance and reactivity to design and manufacture useful items.
How did all start?
The emergence of nanotechnology in the 1980s was caused by the convergence of experimental advances such as the invention of the scanning tunneling microscope in 1981 and the discovery of fullerenes in 1985, with the elucidation and popularization of a conceptual framework for the goals of nanotechnology beginning with the 1986 publication of the book Engines of Creation.
The conceptual origin
The American physicist Richard Feynman lectured, "There's Plenty of Room at the Bottom," at an American Physical Society meeting at Caltech on December 29, 1959, which is often held to have provided inspiration for the field of nanotechnology. Feynman had described a process by which the ability to manipulate individual atoms and molecules might be developed, using one set of precise tools to build and operate another proportionally smaller set, so on down to the needed scale. In the course of this, he noted, scaling issues would arise from the changing magnitude of various physical phenomena: gravity would become less important, surface tension and Van der Waals attraction would become more important.
The Japanese scientist called Norio Taniguchi of Tokyo University of Science was the first to use the term "nano-technology" in a 1974 conference, to describe semiconductor processes such as thin film deposition and ion beam milling exhibiting characteristic control on the order of a nanometer. His definition was, "'Nano-technology' mainly consists of the processing of, separation, consolidation, and deformation of materials by one atom or one molecule." However, the term was not used again until 1981 when Eric Drexler, who was unaware of Taniguchi's prior use of the term, published his first paper on nanotechnology in 1981.
In the 1980s the idea of nanotechnology as a deterministic, rather than stochastic, handling of individual atoms and molecules was conceptually explored in depth by K. Eric Drexler, who promoted the technological significance of nano-scale phenomena and devices through speeches and two influential books.
In 1980, Drexler encountered Feynman's provocative 1959 talk "There's Plenty of Room at the Bottom" while preparing his initial scientific paper on the subject, "Molecular Engineering: An approach to the development of general capabilities for molecular manipulation," published in the Proceedings of the National Academy of Sciences in 1981. The term "nanotechnology" (which paralleled Taniguchi's "nano-technology") was independently applied by Drexler in his 1986 book Engines of Creation: The Coming Era of Nanotechnology, which proposed the idea of a nanoscale "assembler" which would be able to build a copy of itself and of other items of arbitrary complexity. He also first published the term "grey goo" to describe what might happen if a hypothetical self-replicating machine, capable of independent operation, were constructed and released.
Nanotechnology is a multi-disciplinary engineering field, which draws from and benefits areas such as materials science and engineering, chemistry, physics, biology, and medicine
Nano-engineered materials, addresses the synthesis, characterization and engineering application of several classes of advanced materials, including nanocrystalline materials and nanopowders used in electronics and photonics applications, as catalysts in automobiles, in the food and pharmaceutical industries, as membranes for fuel cells, and for industrial-scale polymers.
- The design, synthesis, characterization, application and fundamental studies of new crystalline metal oxide nano-materials that may be used for next-generation rechargeable batteries.
- Nano-engineering of polymer electrolyte membranes. Hydrogen fuel cells use these membranes to combine hydrogen and oxygen and produce energy.
- Development of nano-particles as powerful catalysts for petrochemical refinery applications.
- Basic and applied research in photonic and photonic band gap crystals for optical and microwave communications.
- Design, synthesis, fundamental understanding and processing of polymer nano-composites, which are used in several applications for the automotive, aerospace, electronic components and packaging industries.
Nano-electronics, addresses the development of systems and materials that will enable the electronics industry to overcome current technological limits. Also part of this theme area is a new generation of electronics based on plastics, which is expected to create new markets with applications ranging from smart cards to tube-like computers.
- Experimentation in electron beam lithography, to fabricate nanostructures and nanoelectronic devices, and to determine how the arrangement of molecules affects the chemical properties of substances.
- Fundamental studies and development of nanocrystalline thin-film semiconductors, devices and circuits for electronics and spintronics.
- Development and fabrication of Micro- and Nano-Electro Mechanical Systems (MEMS/NEMS). New devices being researched include NEMS-based metamaterials, miniature signal processing devices, biomedical, diagnostic and image processing devices, tiny wireless components (filters, mixers, antennas), miniature opto-electromechanical devices (optical relays, optical multiplexers, deformable optics), miniature biosensors and environmental sensors, and micro- and nano-fluidics devices.
- Organic synthesis, characterization and application of molecular organic semiconductor materials for electronic/optoelectronic devices. These materials are uniquely positioned to allow low cost fabrication processes (e.g., printable electronics) and to enable novel applications, such as, flexible- and molecular-electronics.
Nano-biosystems, addresses the molecular manipulation of biomaterials and the engineering of nanoscale systems and processes of biological and medicinal interest, such as, for example, the targeted delivery of therapeutic agents and the design of DNA, peptide, protein, and cell chips.
- Interfacing nano-chips to bio-molecules.
- Creation of nano-vehicles that mimic the way viruses interact with specific cells. This will facilitate the delivery of drugs directly to targeted cells, and could, for instance, eliminate the toxic side-effects of chemotherapy by directing the therapeutic agents to cancer cells only.
- Development of nanotechnology methods for therapeutic applications, for example, for replacing faulty DNA or RNA strands with corrected strands.
- Development of nano-techniques for inactivation of microbes: an efficient and cheap method of food sterilization.
Nano-instruments addresses some of the most far-reaching yet practical applications of miniature instruments for measuring atoms or molecules in chemical, clinical, or biochemical analysis; in biotechnology for agent detection; and environmental analysis.
- Lab-on-chip and micro-nano fluidic devices for biodiagnostics and protein sequencing.
- Fundamental studies leading to development of theories behind measurements at the nano-scale.
- Fabrication of instrumentation and development of methodology for micro- and nano-analytical chemistry for measurements of pollutants on-site.
- Using micro as an interface between the nano-scale and the macroscopic, human-scale.
- Development and characterization of mobile micro- and nano- instruments that are small, cheap and under wireless control.
- Measurement of how nano-materials grow and form on surfaces.
- Studies of polymer interfaces, adhesion and confinement of polymer chains glass transition in confined geometries.
What do we have so far?
scientists at the Department of Energy's Oak Ridge National Laboratory have developed a catalyst made of carbon, copper and nitrogen and applied voltage to trigger a complicated chemical reaction that essentially reverses the combustion process. With the help of the nanotechnology-based catalyst which contains multiple reaction sites, the solution of carbon dioxide dissolved in water turned into ethanol with a yield of 63 percent. Typically, this type of electrochemical reaction results in a mix of several different products in small amounts.
How it started
The ideas and concepts behind nanoscience and nanotechnology started with a talk entitled "There's Plenty of Room at the Bottom" by physicist Richard Feynman at an American Physical Society meeting at the California Institute of Technology (CalTech) on December 29, 1959, long before the term nanotechnology was used. In his talk, Feynman described a process in which scientists would be able to manipulate and control individual atoms and molecules. Over a decade later, in his explorations of ultraprecision machining, Professor Norio Taniguchi coined the term nanotechnology. It wasn't until 1981, with the development of the scanning tunneling microscope that could "see" individual atoms, that modern nanotechnology began.
- Once scientists had the right tools, such as the scanning tunneling microscope (STM) and the atomic force microscope (AFM), the age of nanotechnology was born.
- Although modern nanoscience and nanotechnology are quite new, nanoscale materials were used for centuries. Alternate-sized gold and silver particles created colors in the stained glass windows of medieval churches hundreds of years ago. The artists back then just didn't know that the process they used to create these beautiful works of art actually led to changes in the composition of the materials they were working with.
- Today's scientists and engineers are finding a wide variety of ways to deliberately make materials at the nanoscale to take advantage of their enhanced properties such as higher strength, lighter weight, increased control of light spectrum, and greater chemical reactivity than their larger-scale counterparts.
Manufacturing at the nanoscale is known as nanomanufacturing. Nanomanufacturing involves scaled-up, reliable, and cost-effective manufacturing of nanoscale materials, structures, devices, and systems. It also includes research, development, and integration of top-down processes and increasingly complex bottom-up or self-assembly processes.
A product of nanomanufacturing: A 16 gauge wire (above), approximately 1.3 millimeters in diameter, made from carbon nanotubes that were spun into thread. And the same wire on a 150 ply spool (below.) Courtesy of Nanocomp.
In more simple terms, nanomanufacturing leads to the production of improved materials and new products. As mentioned above, there are two basic approaches to nanomanufacturing, either top-down or bottom-up. Top-down fabrication reduces large pieces of materials all the way down to the nanoscale, like someone carving a model airplane out of a block of wood. This approach requires larger amounts of materials and can lead to waste if excess material is discarded. The bottom-up approach to nanomanufacturing creates products by building them up from atomic- and molecular-scale components, which can be time-consuming. Scientists are exploring the concept of placing certain molecular-scale components together that will spontaneously "self-assemble," from the bottom up into ordered structures.
Within the top-down and bottom-up categories of nanomanufacturing, there are a growing number of new processes that enable nanomanufacturing. Among these are:
- Chemical vapor deposition is a process in which chemicals react to produce very pure, high-performance films
- Molecular beam epitaxy is one method for depositing highly controlled thin films
- Atomic layer epitaxy is a process for depositing one-atom-thick layers on a surface
- Dip pen lithography is a process in which the tip of an atomic force microscope is "dipped" into a chemical fluid and then used to "write" on a surface, like an old fashioned ink pen onto paper
- Nanoimprint lithography is a process for creating nanoscale features by "stamping" or "printing" them onto a surface
- Roll-to-roll processing is a high-volume process to produce nanoscale devices on a roll of ultrathin plastic or metal
- Self-assembly describes the process in which a group of components come together to form an ordered structure without outside direction
Structures and properties of materials can be improved through these nanomanufacturing processes. Such nanomaterials can be stronger, lighter, more durable, water-repellent, anti-reflective, self-cleaning, ultraviolet- or infrared-resistant, antifog, antimicrobial, scratch-resistant, or electrically conductive, among other traits. Taking advantage of these properties, today's nanotechnology-enabled products range from baseball bats and tennis rackets to catalysts for refining crude oil and ultrasensitive detection and identification of biological and chemical toxins.
A high resolution image of a graphene transistor with a sheet of carbon only one atom thick. This high speed electronic device was created using nanoscale processes, and may one day be used for better computer hips. (Courtesy of James Yardley, Columbia University Nanocenter, an NNI-sponsored NSEC)
Nanoscale transistors may someday lead to computers that are faster, more powerful, and more energy efficient than those used today. Nanotechnology also holds the potential to exponentially increase information storage capacity; soon your computer's entire memory will be able to be stored on a single tiny chip. In the energy arena, nanotechnology will enable high-efficiency, low-cost batteries and solar cells.
For more products and applications that use nanotechnology, see Benefits & Applications or browse our database of the NNI's Major Achievements in Nanotechnology.
Nanotechnology R&D, and the eventual nanomanufacturing of products, requires advanced and often very expensive equipment and facilities. In order to realize the potential of nanotechnology, NNI agencies are investing heavily in nanomanufacturing R&D and infrastructure. Over 90 NNI-funded centers and user facilities across the country provide researchers the facilities, equipment, and trained staff to develop nanotechnology applications and associated manufacturing processes.
The NNI helps drive the nanomanufacturing field by providing researchers and small businesses with access to this specialized equipment in order to maintain global U.S. competitiveness. To assist in agency coordination in the area of nanomanufacturing, the Nanoscale Science, Engineering, and Technology (NSET) Subcommittee created the Nanotechnology Innovation and Commercialization Ecosystem (NICE) Working Group.
The President's FY 2017 Budget provides $1.4 billion for the National Nanotechnology Initiative, including an estimated $37 million for nanomanufacturing.
The National Nanomanufacturing Network (NNN) is an alliance of academic, government and industry partners that cooperate to advance nanomanufacturing strength in the U.S. The NNI and its member agencies actively participate in, support, and contribute to the NNN in its mission to advance nanomanufacturing.
The NNN functions as part electronic resource, part community of practice, and part network of experts working on the development of nanomanufacturing. The NNN fosters technology transition and exchange through a host of activities including reviews and archiving of emerging materials, processes, and areas of practice, strategic workshops and roadmap development. InterNano is the information arm of the NNN-a digital library resource of timely information on nanomanufacturing and a platform for collaboration, providing information archiving in areas of processes and tools, standards, reports, events, and environmental health and safety databases.
A scanning tunneling microscope (STM) is an instrument for imaging surfaces at the atomic level. Its development in 1981 earned its inventors, Gerd Binnig and Heinrich Rohrer (at IBM Zürich), the Nobel Prize in Physics in 1986. For a STM, good resolution is considered to be 0.1 nm lateral resolution and 0.01 nm (10 pm) depth resolution. With this resolution, individual atoms within materials are routinely imaged and manipulated. The STM can be used not only in ultra-high vacuum but also in air, water, and various other liquid or gas ambients, and at temperatures ranging from near zero kelvin to over 1000°C.
STM is based on the concept of quantum tunneling. When a conducting tip is brought very near to the surface to be examined, a bias (voltage difference) applied between the two can allow electrons to tunnel through the vacuum between them. The resulting tunneling current is a function of tip position, applied voltage, and the local density of states (LDOS) of the sample.Information is acquired by monitoring the current as the tip's position scans across the surface, and is usually displayed in image form. STM can be a challenging technique, as it requires extremely clean and stable surfaces, sharp tips, excellent vibration control, and sophisticated electronics, but nonetheless many hobbyists have built their own.
Atomic-force microscopy (AFM) or scanning-force microscopy (SFM) is a type of scanning probe microscopy (SPM), with demonstrated resolution on the order of fractions of a nanometer, more than 1000 times better than the optical diffraction limit. The information is gathered by "feeling" or "touching" the surface with a mechanical probe. Piezoelectric elements that facilitate tiny but accurate and precise movements on (electronic) command enable very precise scanning.
The AFM has three major abilities: force measurement, imaging, and manipulation.
Cite This Essay
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Every month on Earth Matters, we offer a puzzling satellite image. The August 2016 puzzler is above. Your challenge is to use the comments section to tell us what part of the world we are looking at, when the image was acquired, what the image shows, and why the scene is interesting.
How to answer. Your answer can be a few words or several paragraphs. (Try to keep it shorter than 200 words). You might simply tell us what part of the world an image shows. Or you can dig deeper and explain what satellite and instrument produced the image, what spectral bands were used to create it, or what is compelling about some obscure speck in the far corner of an image. If you think something is interesting or noteworthy, tell us about it.
The prize. We can’t offer prize money, but, we can promise you credit and glory (well, maybe just credit). Roughly one week after a puzzler image appears on this blog, we will post an annotated and captioned version as our Image of the Day. In a blog post, we’ll acknowledge the person who was first to correctly ID the image. We’ll also recognize people who offer the most interesting tidbits of information about the geological, meteorological, or human processes that have played a role in molding the landscape. Please include your preferred name or alias with your comment. If you work for or attend an institution that you want us to recognize, please mention that as well.
Recent winners. If you’ve won the puzzler in the last few months or work in geospatial imaging, please sit on your hands for at least a day to give others a chance to play.
Releasing Comments. Savvy readers have solved some of our puzzlers after only a few minutes or hours. To give more people a chance to play, we may wait between 24-48 hours before posting the answers we receive in the comment thread.
Editor’s Note: The answer to this puzzler was Clew Bay in Ireland, the Bay of the Partly Drowned Hills. Though we had many readers submit the correct location, a special congratulations to Brendan Conway for being the first to do so on Earth Matters. And congratulations also to Thomas Es Thomas for sharing some interesting details about the image on Facebook.
This summer, recent college graduates and early career professionals launched 30 small research projects as part of NASA’s DEVELOP program. The aim is to use NASA satellite observations of Earth to address an environmental or public policy issue. The young researchers have just 10 weeks to do it!
On Aug. 10, 2016, the “DEVELOPers” gathered at NASA Headquarters in Washington, D.C., to showcase their results. So, how can Earth observations solve real-world problems? Let’s take a look:
1. They help land managers identify the locations of invasive species.
Image credit: NASA/Bill Ingalls
Austin Haney, DEVELOP project co-lead at University of Georgia, has seen first-hand how an invasive species can affect the ecosystem of Lake Thurmond, a large reservoir that straddles Georgia and South Carolina. Birds in the area “behave visibly different,” he said, after they consume a toxic cyanobacteria that lives on Hydrilla verticillata, an invasive aquatic plant. Ingesting the toxin causes a neurodegenerative disease and ultimately death. Scores of birds have been found dead in areas where large amounts of the toxin-supporting Hydrilla grow. To help lake managers better address the situation, Haney and project members developed a tool that uses data from the Landsat 8 satellite to map the distribution of Hydrilla across the lake.
2. They help identify wildlife habitat threatened by wildfires.
Image credit: NASA/Bill Ingalls
Maps that depict habitat and fire risk in eastern Idaho previously stopped short of Craters of the Moon National Monument, where shrubs and grasses transition to a sea of ankle-twisting basalt. But the environment is not as inhospitable as it first appears. Throughout the monument there are more than 500 kipukas — pockets of older lava capable of supporting some vegetation. That means they are also prone to burning. Project lead Courtney Ohr explained how her team used data from the Landsat 8 and Sentinel-2 satellites to simulate the area’s susceptibility to wildfires. Decisionmakers can use this model to monitor the remote wildlife habitat from afar.
3. In conjunction with Instagram, they help find seaweed blooms
Image credit: Caribbean Oceans Team
Who knew that Instagram could be a tool for science? One DEVELOP team searched for photographs of massive seaweed (sargassum) blooms in the Caribbean, mapped the locations, and then checked what satellites could see. In the process, they tested two techniques for finding algae and floating vegetation in the ocean.
4. They help conserve water by reducing urban stormwater runoff.
Image credit: NASA/Bill Ingalls
Atlanta’s sewer system is among the nation’s most expensive, yet the city still struggles with stormwater. It’s an uphill climb as new construction paves over more of the city, removing landscapes that could absorb rain. The University of Georgia DEVELOP team partnered with The Nature Conservancy to address the problem.
Using satellite imagery, the team pinpointed 17 communities ripe for more green infrastructure and reforestation that could capture more of the city’s runoff. The team used two models — Land-Use Conflict Identification Strategy and the Soil and Water Assessment Tool — as well as the Landsat and Terra satellite data. Their analysis provides local groups with a working picture of the city’s water resources.
5. They show the spread of the mite eating away Puerto Rico’s palm trees.
Image credit: NASA/Bill Ingalls
The red palm mite has devastated Puerto Rico’s trees in recent years, chewing through coconut palms, bananas, and plantains on the island. The pests have spread and hurt crops across the Caribbean.
A DEVELOP team led by Sara Lubkin analyzed satellite imagery to track the mites’ rapid spread from 2002. The team mapped changes to vegetation (such as yellowing) and differences in canopy structure. They made use of imagery from Landsat, Hyperion, and IKONOS, as well as aerial views. Their work can be used to mitigate current mite infestations and monitor and prevent future ones.
6. They evaluate landslide-prone areas in the developing world
Image credit: East Africa Disasters II Team
One team of DEVELOPers took on a project to aid people in developing nations. They examined satellite imagery to find past landslides in the African nation of Malawi. Factors such as flooding after long periods of drought have made the country increasingly prone to landslides. Blending maps of the landscape, rainfall data, and population centers, the young researchers assessed the areas most at risk—and most in need of education and support—from landslides.
Want to read more about DEVELOP projects? Want to get involved? Summaries, images, and maps of current and past projects can be viewed HERE. You can also learn how to apply for the DEVELOP program HERE.
NASA Earth Observatory image by Joshua Stevens. Learn more about individual images here.
“Thousands of tired, nerve-shaken, over-civilized people are beginning to find out that going to the mountains is going home; that wildness is a necessity” ― John Muir, Our National Parks
Happy Birthday to the U.S. National Park Service! A century after President Woodrow Wilson signed the bill that established the National Park Service, there are now 420 national parks, monuments, battlefields, military parks, historical sites, lake shores, seashores, recreation areas, and scenic rivers and trails. Interestingly, the first National Park—Yellowstone—was established in 1872, well before the park service.
Also, stay tuned to that image gallery page. We will continue to add images throughout the week and for the rest of the year. Follow the links to read more quotes about the park system and wilderness. And if you want to see even more imagery of national parks from space, check out this gallery of astronauts photographs of some of the more famous parks.
“Laws change; people die; the land remains.” ― Abraham Lincoln, 16th President of the United States
NASA Earth Observatory map by Joshua Stevens, using data from the National Park Service and the U.S. Fish and Wildlife Service.
On August 13, 2016, we published an image and video showing meteors streaking across the night sky. The perspective is a new one. Instead of looking up from the ground, the camera recorded the action from the vantage point of the International Space Station (ISS). In case you missed it, you can see the image and read the full story here. The video is reposted below.
At 6 and 16 seconds into the video, bright meteors dash across the sky over Pakistan. The video was acquired a few days before the annual Perseid meteor shower reached its peak. But as one reader pointed out to us via email, only one of these meteors can be associated with the shower. The reason? The view from orbit shows them travelling in different directions.
Meteors within a shower all travel in roughly the same direction and speed. The map below illustrates that point, showing the ground tracks and speed of all Perseids observed in the United States in July and August 2016 by the ground-based all sky camera network. The map shows all Perseids within range of a camera; blank areas are outside the range of a camera.
“Note how their paths all move from top right to bottom left,” said Bill Cooke with NASA’s Meteoroid Environments Office. “This is what would be seen from the ISS or another space platform.”
Showers look vastly different to a person standing on the ground looking up at a wide view of the night sky. From this perspective, meteors associated with a shower can appear to radiate outward from a central point called the “radiant.” The central point in the night sky is linked to the shower’s name; the Perseids, for example, appear to stem from the area of sky near the constellation Perseus.
The phenomenon, however, is an illusion of perspective. The illusion has been compared to flakes that appear to radiate outward as you drive through a snowstorm, or parallel train tracks that appear to converge in the distance.
“The perspective from orbit is somewhat different, because you are not looking at the entire sky, just a small fraction of the total area,” Cooke said. “In this case, meteors from a particular shower will be all moving the same direction.”
So which meteors viewed from orbit are belong to a particular shower, and which are “sporadic meteors?” That’s the type of information that will ultimately be gleaned from the diffraction grating on the space station’s Meteor camera. It will collect spectroscopy data that can tell scientists about a meteor’s composition, which can ultimately be related back to the parent body—comet Swift-Tuttle, in the case of the Perseids.
Many of the Olympic festivities are taking place in Barra da Tijuca, one of the youngest and most affluent neighborhoods in Rio. Credit: Landsat 8/NASA Earth Observatory.
While gymnasts leap, cyclists pedal, and divers twirl for Olympic gold in Rio de Janeiro, sensors on several NASA Earth Observing satellites are catching glimpses of the city and its surroundings from space. The mix of satellites and sensors in orbit are nearly as varied and diverse as the athletes competing below.
The marathoner among NASA’s fleet would have to be Terra. Despite having a design life of six years, this reliable spacecraft has been in orbit since 2000. The multi-purpose satellite carries five scientific payloads and monitors everything from phytoplankton to forest cover to airborne particles called aerosols.
The swimmers would have to be Aquarius, Aqua, and the Global Precipitation Measurement (GPM). All three satellites, as their names suggest, specialize in studying water. Aquarius focuses on measuring the ocean’s salinity. Aqua, like Terra, is versatile: It studies water vapor, sea ice, snow ice, clouds, and more. GPM is the newest of the trio. Launched in 2014, it makes global maps of precipitation and sets standards for precipitation measurements worldwide.
The synchronized divers of space would have to be the Gravity Recovery and Climate Experiment (GRACE). While divers seem to temporarily defy gravity with their flips and turns, the pair of GRACE satellites actually measures Earth’s gravity from space.
The twin GRACE satellites. Credit: NASA
The archers would be CALIPSO and CloudSat. These two satellites shoot laser pulses (CALIPSO) and radar waves (CloudSat) down toward features in the atmosphere such as clouds and smoke plumes. They measures precisely how long it takes for the light or radio waves to bounce back, making it possible to map the vertical structure of the atmosphere.
The images above and below offer a glimpse of some of the types of imagery and data that NASA-Earth observing satellites collect. The image at the top of the page shows how Olympic Park in Rio appeared to the Operational Land Imager (OLI), a sensor on Landsat 8. The image immediately above shows Rio at night as seen by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite. The instrument can sense light 100,000 times fainter than conventional visible-light sensors, making it extremely sensitive to moonlight and city lights.
The image directly above shows a view of Rio and Guanabara Bay on August 6, 2016, the day after the opening ceremony. The fourth image (below) shows a view of aerosols observed over Rio by the Multi-Angle Imaging Spectrometer (MISR) on August 2, 2016.
Scientists at NASA and officials in the Rio de Janeiro government recently signed an agreement about natural hazards preparedness. The hope is that satellite imagery and data—in conjunction with in situ data from the ground—will help scientists better understand, anticipate, and monitor drought, flooding, and landslides that occur in and around Rio. The collaboration will focus on integrating, visualizing, and sharing relevant data from NASA satellites.
Severe mudslides and landslides affected Rio in 2011. Read more about this image here. Credit: EO-1/NASA Earth Observatory
In a NASA press release, Rio de Janeiro Mayor Eduardo Paes said that his city has historically suffered from massive rainstorms and subsequent floods and landslides, all of which can cause casualties and disrupt the economy. Discussions are underway to address those hazards and to plan future cooperative activities.
The 2015 fire season was the most severe ever observed by NASA Earth Observing System satellites, a new study shows. As we reported in December, 2015 was an intense fire season in Indonesia because the drying effects of El Niño exacerbated seasonal fires lit by growers. Many farmers lost control of fires, which then spread through dried-out peat deposits. Peat fires produce thick, acrid smoke rich with greenhouse gases.
Some of the results from their analysis are shown in the chart below. Note that red lines indicate trends in 2006 (also a severe fire year); blacks lines indicate 2015. The tick marks on the X-axis indicate the month of the year. Comparing the two years, it is clear that 2015 was the more severe fire season. The sensors generally detected higher levels (or longer duration of emissions) of each pollutant in 2015. The peak number of fires observed by MODIS was slightly higher in 2006, but the sensor detected more fires overall in 2015. In both 2006 and 2015, fire activity increased rapidly as rainfall decreased.
To see how the 2015 fires compared to severe fire seasons before the Earth Observing System satellites were in space, Goddard Institute for Space Studies scientist Robert Field looked back at longer-term records of visibility collected at Indonesian airports. The chart below compares visibility in 2015 with 1997 and 1991—two other years that were dry because of El Niño. (Note: Bext stands for extinction coefficient; a higher extinction coefficient means more smoke was in the air. The upper part of the chart shows how much rain fell. In that chart, “CPC pcp” stands for precipitation from the Climate Prediction Center, a NOAA research group.) By that measure, 1997 was a far more severe fire season. In Sumatra, visibility was also lower in 1991, though in Kalimantan. visibility was about the same in 2015 and 1991.
“Without significant reforms in land use and the adoption of early warning triggers tied to precipitation forecasts, these intense fire episodes will reoccur during future droughts, usually associated with El Niño events,” the authors emphasized.
+Read a NASA press release about the study here.
+Read a more detailed story about the 2015 fires here.
In Indonesia, dry weather can mean fire. September 2015 data from the TRMM satellite shows lack of rainfall in the areas where fire broke out. Image by NASA Earth Observatory.
Comments Off on Just How Bad was the 2015 Fire Season in Indonesia? | <urn:uuid:ea906d6a-f8d4-4c7d-b44b-4bf7afc990fc> | 3.046875 | 3,638 | News (Org.) | Science & Tech. | 45.771326 | 95,565,825 |
The massive submarine flow travelled 1,500 kilometres – the distance from London to Rome – before depositing its load.
Details of the landslide and consequent sediment flow are reported online today in Nature by Dr Peter Talling from the University of Bristol, with colleagues from the National Oceanography Centre in Southampton and several other institutions.
Dr Talling said: “The volume of sediment transported by this flow in the deep ocean is difficult to comprehend. It was one of the largest movements of material ever to occur on our planet. This mass was ten times that transported to the ocean every year by all of the Earth’s rivers. The flow was sometimes over 150 km wide, spread across the open sea floor.”
Perhaps the most remarkable thing about this giant submarine flow is that it travelled hundreds of kilometres without depositing any sediment on the vast expanse of sea floor that it passed over.
Sediment deposition was finally triggered by a remarkably small but abrupt decrease in sea-floor gradient (from 0.05˚ to 0.01˚). For comparison, most premiership soccer pitches have a gradient of less than 1˚ to help their drainage.
Man is placing more and more structures on the sea floor, including installations for recovering subsurface oil and gas reserves that can be worth hundreds of millions of dollars. Understanding the cause and evolution of these infrequent undersea flows helps to assess any potential hazards posed to such structures.
Installations involved in oil and gas recovery are typically sited on slopes of greater than 0.05˚. Cores collected next to these installations to help design their foundations are often used for subsequent geohazard analysis.
This work suggests that a more accurate record of these flows is found by coring in the low-gradient basin plains which may be hundreds of kilometres from the installations.
Cherry Lewis | EurekAlert!
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...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:eb6e9407-aa9f-4c3b-9c0b-0713b65580f9> | 3.734375 | 1,005 | Content Listing | Science & Tech. | 41.943251 | 95,565,858 |
We found 82 resources with the concept chlorophyll
Why Aren't Plants Black?
7 mins 9th - Higher Ed CCSS: Adaptable
In an evolutionary sense, plants seem to have it all figured out. But, do they really? The narrator of an engaging physics video that is part of a larger series questions the predominant color of plants in a short video. Content includes...
Why Do Leaves Change Color?
2 mins 9th - Higher Ed CCSS: Adaptable
Discover the scientific explanation of fall leaves! The lesson narrator describes the role of chlorophyll, glucose, and weather in the process of the color-changing process. He adds an overview of carotenoids and flavonoids to explain...
The Real Reason Leaves Change Color in the Fall
3 mins 6th - 12th CCSS: Adaptable
Discover the chemistry behind the color change in leaves. The lesson narrator describes how trees must recycle nutrients in the leaves before they fall off for the winter. The video breaks down the process and highlights the chemistry of... | <urn:uuid:1c8c306c-0807-43ab-b141-955d6e01900a> | 3.796875 | 215 | Content Listing | Science & Tech. | 63.981125 | 95,565,859 |
|ECHINODERMATA : DENDROCHIROTIDA : Cucumariidae||STARFISH, SEA URCHINS, ETC.|
Description: A small sea cucumber with white skin and tube-feet in 5 zigzag rows. There are 10 sparsely branched white tentacles. The spicules are numerous and each one is knobbly with 4 holes. There is a superficial layer of smaller star-shaped cup spicules. Usually only 1cm long, occasionally up to 4 cm.
Habitat: This is an epifaunal species living amongst shells and other sessile animals.
Distribution: Found on the south, west and north-east coasts of the British Isles.
Similar Species: Has been confused with the small form of Ocnus planci in the past.
Key Identification Features:
Distribution Map from NBN: Interactive map : National Biodiversity Network mapping facility, data for UK.
WoRMS: Species record : World Register of Marine Species.
|Picton, B.E. & Morrow, C.C. (2016). Ocnus lacteus (Forbes & Goodsir, 1839). [In] Encyclopedia of Marine Life of Britain and Ireland. |
http://www.habitas.org.uk/marinelife/species.asp?item=ZB4840 Accessed on 2018-07-18
|Copyright © National Museums of Northern Ireland, 2002-2015| | <urn:uuid:bd0115c9-cf22-483b-8f82-2124a2154ec7> | 3.21875 | 312 | Knowledge Article | Science & Tech. | 52.670147 | 95,565,893 |
Pressure in the Deep-ocean: an experiment with a foam ball
Everything in the deep ocean is under great pressure. The pressure increases about one atmosphere for every 10 meters of water depth. In order to test this pressure, a student from EPM in collaboration with EMPC and ISE,USJ, dove an expanded polystyrene foam (EPF) uniform ball into deep-water using the Portuguese remotely operated vehicle (ROV), called Luso (EMEPC).
Decoration of the ball was made by the EPM student Pedro Gonçalves and Patricia Conceição was the geologist (EMEPC) aboard NRP GAGO COUTINHO who carried out the experiment. Patrícia placed the ball in a mesh bag attached to the ROV Luso that plunged into the deep-ocean, reaching a depth of several hundred meters.
After the dive was complete and the ROV back to the surface, the ball returned smaller and shrunken. This happened because when the foam ball descended into the ocean attached to the ROV, tiny air bubbles entrapped in the polystyrene structure were compressed, crushed and released, reducing the total volume of the material.
#ise_usj #usjmacau #deepsea #emepc #ROVLuso #epm #epmmacau #macau | <urn:uuid:61d3f458-ff26-449d-8789-15fb50c616a8> | 3.265625 | 287 | News (Org.) | Science & Tech. | 27.494032 | 95,565,896 |
Dataset Details - Dragonfly Records
Dragonfly and damselfly data collated from records submitted to the National Biodiversity Data Centre.
Record and understand the geographic distribution of dragonflies and damselflies in Ireland.
Field observations supported by photographs where necessary.
The island of Ireland.
1994 to present.
All records validated prior to submission to Dragonfly Ireland.
http://www.habitas.org.uk/dragonflyireland & https://www.facebook.com/pages/DragonflyIreland/206848686003391
Open (Creative Commons CC-BY 4.0)
Collated by the National Biodiversity Data Centre from different sources, Dragonfly Records, National Biodiversity Data Centre, Ireland, accessed 18 July 2018, <https://maps.biodiversityireland.ie/Dataset/239>
Dataset species distribution
Terrestrial Map - 10kmDistribution of the number of species recorded within each 10km grid square (ITM).
Marine Map - 50KmDistribution of the number of species recorded within each 50km grid square (WGS84).
Dataset record distribution
Terrestrial Map - 10kmDistribution of the number of records within each 10km grid square (ITM).
Marine Map - 50KmDistribution of the number of records within each 50km grid square (WGS84).
Dr. Tomás Murray
Records per year
Species per year
|Abundance||Measure of abundance of the organism recorded|
|Determiner name||The name of the person(s) who verified the identification - used for verify records of difficult taxa|
|Life stage||A description of the life stage of the organism recorded.|
|Record comment||A comment associated with any individual record|
|Sex||The sex of the organism if known.|
|Loading data from server| | <urn:uuid:138b875c-45b9-4048-9f5b-72ce37e13ec0> | 2.640625 | 405 | Structured Data | Science & Tech. | 35.087496 | 95,565,897 |
Description - Fluids, Materials and Microgravity by Marcello Lappa
Each year, universities and research centres - most particularly the major space agencies such as NASA, ESA, and NASDA - devote a vast amount of time and money into the research of materials behaviour and production in microgravity. Recently, the possibility of creating special alloys, inorganic and organic crystals, as well as biological (living) tissues in this condition has been investigated.
Fluids, Materials and Microgravity provides a solid basis of established knowledge - through literature, fundamental studies, experimental methods, numerical (basic and sophisticated) techniques - as well as the latest in research advancements. Important for the prediction of material behaviour when exposed to the environment of space, this book explores the new knowledge provided by microgravity-based studies in producing unique inorganic, and organic materials on Earth (and in designing related new technological processes). A vital resource for any scientists interested in the understanding and modelling of the new important physical mechanisms disclosed by microgravity research, and in their possible effect on the production and behaviour of materials both in space and on Earth.
A vital resource for any scientists interested in the effect of microgravity on the production and behaviour of materials.
Buy Fluids, Materials and Microgravity by Marcello Lappa from Australia's Online Independent Bookstore, Boomerang Books.
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A famous mathematical formula which shook the world of ecology 40 years ago has been revisited and refined by two University of Chicago researchers in the current issue of Nature.
In 1972, physicist Robert May rankled ecologists by publishing a simple model describing the relationship between diversity and stability in a theoretical ecosystem. Though ecologists had long believed that richer, more diverse environments were inherently more resistant to disruption, May's formula argued that more species in fact creates more instability.
But rich ecosystems exist in nature, such as those found in coral reefs or rain forests. For 40 years, ecologists have attempted to expand May's formula to explain how these highly diverse natural systems persist. For the new paper, University of Chicago researchers Stefano Allesina and Si Tang returned to the original equation, and with small mathematical tweaks, reconciled the disagreement between theory and reality.
Adjusting May's formula to incorporate predator-prey or consumer-resource relationships, where one species profits at the expense of another, allows the model to describe an ecosystem where stability is possible even with an infinite number of species.
"Predator-prey relationships are stabilizing. We can fit much larger ecosystems if there's a backbone of predator-prey interactions, and see a lot of species happily co-existing ever after," said Allesina, PhD, assistant professor of Ecology & Evolution at the University of Chicago. "We kind of solved this one puzzle of how can we see very many species in an ecosystem. But then we open different puzzles."
May's original model, also published by Nature, sought to challenge the ecological belief that diverse ecosystems were more resistant to perturbations such as invasive species or abrupt climate change. With his physics training, May set out to create a model of the relationship between diversity and stability with the fewest possible factors, settling upon a model that used only the number of species and the strength of their interactions with each other.
The surprising result of May's model was that large or complex ecosystems were so unstable that their existence was statistically improbable. While that conclusion did not match what ecologists observe in natural systems such as rain forests, which may contain thousands of species in a single tree, the model challenged the simplistic assumption of more diversity leading to more stability.
"May made the beautiful point that nature must adopt some 'devious strategies' to cope with this fact, because if mathematically there is this impossibility of complexity, how come we then observe it in nature?," Allesina said. "It must be that nature uses some sneaky way to violate this rule."
May's article launched the "diversity-stability debate," as ecologists proposed many such "devious strategies" to explain the persistence of rich ecosystems in nature by adding complex qualifiers to his formula. Instead of following this trend, Allesina and Tang went back to the original model and made a small adjustment. They replaced the random species interactions of May's model with three general types of relationships observed between species in nature.
In the "eat-or-be-eaten" world of a predator-prey relationship, one species (the predator) benefits while another species (the prey) suffers a loss of fitness. A competitive relationship between two species can have a negative effect on both, while a relationship of mutualism produces a positive effect for the two species involved.
When each of these interactions is inputted separately into May's formula, the predicted stability for a given number of species changes from his original calculation using a random distribution of species-species interaction. In the predator-prey condition, the stability of the ecosystem is increased such that a large number of species can be supported. In the competition and mutualism systems, the ecosystem is highly unstable and vulnerable to perturbation.
"What we are showing is that of all the types of interactions you can have, only predator-prey can support an infinite number of species," Allesina said. "If you look in nature, there are very obvious consumer-resource relationships everywhere, and maybe this system assembles so easily because these relationships provide a lot of stability."
But just as the revised version of May's formula brings it in line with one natural observation, more counter-intuitive results are created. Many ecologists believe that strong interactions between species, such as when a predator relies upon only one prey species for food, make an ecosystem more vulnerable. However, the revised formula predicts that weak interactions, not strong interactions, are destabilizing to an ecosystem.
Another discrepancy occurs when the model is applied to a realistic food-web structure, rather than the theoretical, random structure used as a default. When a commonly observed natural structure— such as the "cascade" model where each predator eats prey smaller than themselves—is tested with the model, the resulting system is less stable than that produced by a random structure.
But like May's original formula, these disagreements between model and reality offer new opportunities to explore how nature subverts these predictions and produces diverse, stable ecosystems. Many of the "devious strategies" proposed as additions to the original model can now be tested with the revised formula as a reference point.
"I think this is a good step forward, especially because it resuscitates this result that has been so fundamental for theoretical ecology, but no one since has touched it," Allesina said. "Everybody cited it, and kind of disproved it metaphorically, but it's nice to go back to the original formulation and extend it."
The paper, "Stability criteria for complex ecosystems," will be published online February 19th by Nature [doi: 10.1038/nature10832]. Funding for the work was provided by the National Science Foundation.
For more news from the University of Chicago Medicine and Biological Sciences, follow us on Twitter at @UChicagoMed, or visit our Facebook page at facebook.com/UChicagoMed, our research blog at sciencelife.uchospitals.edu, or our newsroom at uchospitals.edu/news.
Robert Mitchum | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Catharina James is a pioneering material scientist whose revolutionary work on graphene has the potential to reshape the global manufacturing industry and create a more sustainable economy.
Two hundred times stronger than steel, thirty times more thermally conductive than copper, a super-conductor, ultra-thin and lightweight, impermeable, stretch-able…it’s easy to see why graphene has been dubbed the wonder material of the 21st century.
From radiators and loudspeakers you can spray onto walls, to hyper-efficient batteries and detecting structural faults in buildings, the potential uses are huge and will permeate into all areas of our lives.
But it is notoriously difficult to create graphene in large quantities and at high quality. At least, it was until Catharina and her co-founders at Cambridge Nanosystems devised a stable, energy-efficient, single-step process to turn biogas into high-quality graphene powder on an industrial scale.
It’s an innovation that has come closer than any to making widespread use of graphene a reality. And, in making graphene by breaking down harmful greenhouse gases such as methane, it has potentially enormous positive consequences for the environment as well.
Catharina is the Chief Scientist at Cambridge Nanosystems, where she oversees the company’s research strategy and technology roadmap. She has a PhD in Material Science from the University of Cambridge and was recently awarded a Fellowship at the RSA (Royal Society for the encouragement of Arts, Manufactures and Commerce) in recognition of her work.
Watch Catharina’s TED Talk here
Image copyright: Catharina James
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This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations. (July 2012) (Learn how and when to remove this template message)
A predator trap is a natural hazard such as a tar pit. Predators would become attracted to struggling animals that have become entrapped in viscous or glutinous material, such as a heavy sedimentary deposit or tar and, in the process, become entrapped themselves. More predators, scavengers, insects and birds become attracted to this mounting accumulation of carrion, until a wide variety of animals are caught and ultimately killed by the hazard. This may happen many times over. Typically, the number of lured predators will greatly outnumber the prey, thus providing the name.
A famous example is the La Brea Tar Pits site. The Cleveland-Lloyd Dinosaur Quarry may yet prove to be a further example, although still nowadays it is debated if it's a predator trap or not. The Gobi Desert dinosaur death traps may have been sauropod footprints that have been filled with a mixture of thick mud & sandstone in the former wetland.
- L.A.'s Oldest Tourist Trap - The La Brea Tar Pits. | <urn:uuid:9ee31f53-e4b5-4bc9-bbfa-42d9de78fce6> | 3.796875 | 258 | Knowledge Article | Science & Tech. | 43.334575 | 95,565,947 |
Traffic lights, neon-lit advertisements, a jungle of road signs. When learning to drive, it is often very difficult to distinguish between important and irrelevant information. How the brain learns the importance of certain images over others is being investigated by Prof. Sonja Hofer at the Biozentrum of the University of Basel.
In a recently published study in “Neuron”, the neuroscientist and her team show that learning the relevance of images considerably modifies neuronal networks in the brain. These changes might help our brain to process and classify the overload of stimuli in our environment more effectively.
How we perceive our environment greatly depends on what we have previously seen and learnt. For example, expert drivers do not need to think twice about the meaning of different road signs and are experienced in assessing traffic situations.
They can filter out relevant information from a flood of other irrelevant stimuli and thus react quickly. In contrast, beginners need much longer to process the new information. Prof. Sonja Hofer’s team at the Biozentrum of the University of Basel and University College London addressed the question of how processing of sensory stimuli is optimized in the brain through learning.
The brain learns to discriminate between images
To do this, Prof. Hofer’s team investigated the visual cortex of mice. This part of the brain is responsible for the processing and perception of visual stimuli. Mice ran through a virtual-reality environment where they encountered various images, one of which was paired with a reward. Within one week, the animals had learnt to discriminate between the images and to respond accordingly.
This learning was reflected in the activity of nerve cells in the visual cortex whose responses were recorded and tracked over the course of learning. While the responses in the brain to the relevant visual stimuli were quite unspecific in beginner mice, many more neurons reacted specifically to the shown images after one week of training.
Learning optimizes stimulus processing
“From day to day, the response of the neurons to the images became increasingly distinguishable and reliable”, says Adil Khan, one of the two first authors. He speculates that such changes in the brain might also allow us to process important information from our environment more efficiently, and perhaps underlies our ability to react promptly to important visual stimuli.
The scientists also demonstrated that diverse internal and external signals affect the processing of the visual stimuli. “We observed that the response of the nerve cells to the same visual stimuli became less accurate when the mice where engaged in another task, such as having to discriminate between different smells. The visual stimuli then lose their relevance and are no longer so effectively analyzed by the brain”, says Khan.
“Remarkably, the expectation of a stimulus even before it appears, and the anticipation of a reward also altered the activity of specific brain cells. This means that from one moment to the next our brain might process the same stimulus quite differently depending on its importance and relevance.”
Internal signals influence visual perception
Traditionally it was thought that the visual cortex exclusively processes visual information. This study, however, corroborates that during learning also many other signals from various brain regions influence activity in this brain area. “This means that our previously learnt knowledge, our expectations and the context we are in can have a great impact on our visual perception of the environment”, explains Hofer.
Jasper Poort, Adil G. Khan, Marius Pachitariu, Abdellatif Nemri, Ivana Orsolic, Julija Krupic, Marius Bauza, Maneesh Sahani, Georg B. Keller, Thomas D. Mrsic-Flogel, and Sonja B. Hofer
Learning Enhances Sensory and Multiple Nonsensory Representations in Primary Visual Cortex
Neuron; published online 5 June 2015, doi: 10.1016/j.neuron.2015.05.037
Katrin Bühler | Universität Basel
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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A new approach to generate uniform-sized nanoliter droplets inside a simple microfluidic chip was developed by using a circular groove to break off the liquid infused from the surrounded inlet. We characterized the droplet formation by using circular grooves with different diameters ranging from 1.2 to 2.4 mm. Monodisperse droplets with a very narrow size distribution (RSD < 0.56%, n = 70 droplets) can be reliably produced and the volume of droplets varied between 74 and 576 nl by using different circular grooves. Influences of liquid properties on droplet formation were also investigated, including surface tension, viscosity and density. Moreover, the transport of droplets and reliable coalescing of two neighboring droplets were realized by using Y-shaped guiding lanes with two different designs. Controlling the velocities of each droplet based on their different physical properties or slowing down the first droplet relying on a pinched segment of the guiding lane has been developed. These methods have been used to control the contact conditions of two reagents coalescing in a 'head-to-tail' mode.
Mendeley saves you time finding and organizing research
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Molecules Brilliantly Illuminated
News Apr 24, 2018 | Original Story from Ludwig-Maximilians-Universität München.
Credit: Alexander Gelin.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of health. Researchers led by Ferenc Krausz at the Laboratory for Attosecond Physics (LAP) – a joint venture between Ludwig-Maximilians-Universität (LMU) and the Max Planck Institute for Quantum Optics (MPQ) in Munich – want to use brilliant infrared light to study molecular disease markers in much greater detail, for example to facilitate early stage cancer diagnosis. The team has developed a powerful femtosecond light source which emits at wavelengths between 1.6 and 10.2 micrometers. This instrument should make it possible to detect organic molecules present in extremely low concentrations in blood or aspirated air.
Myriads of molecules react in highly specific ways to light of certain wavelengths in the mid-infrared region. By absorbing particular wavelengths, each type of molecule in a sample imprints a specific signature on the transmitted beam, which serves as a molecular fingerprint. With a source of broadband mid-infrared light one detects the fingerprints of many molecular structures at once – in a sample of blood or aspirated air, for example. If the sample contains marker molecules that are associated with specific disease states, these too will reveal their presence in the spectrum of the transmitted infrared light.
LAP physicists have now constructed such a light source, which covers the wavelengths between 1.6 and 10.2 microns. The laser system exhibits watt-level average output power, and is well focusable which results in a highly brilliant infrared light source. This feature enhances the ability to detect molecules present in extremely low concentrations. In addition, the laser can produce trains of femtosecond pulses [a femtosecond is a millionth of a billionth of a second (10-15 sec)], which makes it possible to carry out time-resolved as well as low-noise and highly- precise measurements.
At present, infrared spectroscopy is often based on the use of incoherent light, which provides coverage of the whole mid-infrared region. However, the relatively low brilliance of the beam produced by incoherent sources markedly reduces the ability to detect very weak molecular fingerprints. Synchrotron radiation produced in particle accelerators can alternatively be used, but such facilities are in short supply and are extremely expensive. However, laser-based methods can generate even brighter beams than synchrotrons do. The physicists at LAP have now succeeded in building a coherent light source which produces brilliant laser light over a broad spectral region in the infrared range. That used to be the major drawback of laser sources Moreover, the new system has a much smaller footprint (and is far less costly) than a synchrotron: it fits on a large table.
“Of course, there is still a long way to go until we can diagnose cancer at much early stage than at present. We need a better understanding of disease markers and we have to design an efficient way to quantify them, for example,” says Marcus Seidel, one of the researchers involved in the project. “But now having significantly improved light sources available, we can begin to tackle these issues.” Moreover, the new laser system will find applications in areas beyond the biosciences. After all, the precise observation of molecules and their transformations is at the core of both chemistry and physics too.
This article has been republished from materials provided by Ludwig-Maximilians-Universität München. Note: material may have been edited for length and content. For further information, please contact the cited source.
Marcus Seidel et al. Multi-watt, multi-octave, mid-infrared femtosecond source. Science Advances, 2018 DOI: 10.1126/sciadv.aaq1526.
Nano-tech Diagnostic Can Indicate Cancer or Thrombotic Risk in One Drop of BloodNews
A team of international researchers led by Professor Martin Hegner, Investigator in CRANN and Trinity’s School of Physics, have developed an automated diagnostic platform that can quantify bleeding – and thrombotic risks – in a single drop of blood, within seconds.READ MORE | <urn:uuid:fd6d23e5-d59b-4380-b5c1-7fce112c022d> | 3.421875 | 930 | News Article | Science & Tech. | 34.765198 | 95,565,964 |
At Christmastime, one of our warm and fuzzy traditions is to kiss under the mistletoe. But did you know
The first set of criteria determines whether the completion of a parasitic plant’s life cycle is solely dependent on its association with a host plant. If it is, the plant is considered an obligate parasite. If the plant has the potential to survive independent of a host, it is known as a facultative parasite.
The second set of criteria assesses the type of attachment the parasitic plant has to its host. If it attaches to a host’s root, for instance, it is a root parasite. If it attaches to a host’s stem, it is, you guessed it, a stem parasite.
The third set of criteria classifies parasitic plants according to their ability to produce their own chlorophyll. Parasitic plants are considered .
Mistletoe, so lovingly described in this article’s opener, is an obligate stem hemiparasite.
Parasitic Plant Damage
It is important that we are aware of this parasitic plant info because parasitic plant damage can have serious repercussions. The stunted growth and death that afflict the parasites’ host plants can happen on a massive scale and threaten vital food crops or even disrupt the delicate balance in ecosystems and all who exist within it. | <urn:uuid:1315f298-edc2-4c63-93a0-b2b3c62cecfd> | 3.609375 | 277 | Knowledge Article | Science & Tech. | 40.123333 | 95,565,967 |
12 July 2018
Hot and cold
Published online 23 June 2018
A new thin-film device can switch between different states by controlling heat flow.
Voltage-induced electrical stress can trigger chemical reactions in a semiconducting thin film, forming nanofilaments that also act as conductors, according to new research1.
“Thin film with such properties is potentially useful for making power-generating devices which can convert waste heat into electricity,” says lead author José Ramón Durán Retamal from King Abdullah University of Science and Technology (KAUST), Saudi Arabia.
The conducting filaments increase current flow inside the film and lower heat transport.
This is also reversible; dialing down electrical stress disrupts the formation of conducting nanofilaments, reducing current flow and increasing heat transport inside the film.
In short, by tweaking voltages that increase or decrease electrical stress, the scientists could switch between the two states.
The film thus makes it possible to achieve both cooling and power generation using the same material, says Retamal.
The device was prepared by placing a thin film of bismuth manganese oxide between two platinum electrodes on a silicon substrate.
The researchers, led by Jr-Hau He from KAUST, say that because this electrically controllable film could produce different levels of heat and coldness, it has the potential to reduce power consumption of devices that convert waste heat into electricity.
- Retamal, J. R. D. et al. A nanostructuring method to decouple electrical and thermal transport through the formation of electrically triggered conductive nanofilaments. Adv. Mater. https://doi.org/10.1002/adma.201705385 (2018) | <urn:uuid:4e819686-8036-4c12-a51b-5a7ec72d5c05> | 3.3125 | 367 | Truncated | Science & Tech. | 37.838898 | 95,565,970 |
+44 1803 865913
By: Peter Bunyard
254 pages, Illus, figs, tabs
Gives a clear overall picture of climte from its origins to the present day, comparing the cause and effect of natural changes with human influences.
'This book needs to be read, to be bought, or ordered from the local library.' -- Y Fignn Cymmis, Winter 1999 'Peter Bunyard has waded through a morass of information about how the climate system works and has communicated the key ideas in a style which is engaging, illuminating, succinct and accessible to non-scientists. This book is a very good place to start if you are beginning to explore the Earth system and our impact upon it.' -- Stephen Harding, Resurgence, October 2000 'Gives a clear overall picture of climate from its origins to the present day, comparing the cause and effect of natural changes with human influences. Almost anyone seeking a guide to climate science, in plain language that is clear and well-structured but does not shy away from complexities, will find what they need in this book. Even if you think you know quite a bit already, here is almost everything you ever wanted to know but were too afraid to ask.' -- Caspar Henderson, The Ecologist, October 2000 'Sobering and well-informed. The value of the book is that it gives a complete overview of climate as a whole, so that the reader can clearly understand how human activities have impacted on planetary systems, including the balancing act performed by oceanic currents and tropical forests. Essential reading in this field.' -- Scientific and Medical Network Review, December 1999
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Congress is considering legislation that could weaken the Endangered Species Act.
The vast majority of the U.S. had a warm winter, driven in part by intense February heat.
Scientists will pick 50 coral reefs worldwide to test ways to limit damage from climate change, pollution and over-fishing.
Record February heat is kickstarting spring from the Southeast to the Midwest.
The season and area in which trees are tapped to produce maple syrup is warming from climate change.
As the climate warms, maples are being tapped earlier in the year to get the sap that produces syrup.
If you're looking for romantic news this Valentine's Day, climate change has you covered.
U.S. forest health and the ability of farmers to respond to climate change are at risk under Trump's USDA.
Scientists are seeing an uptick of mercury levels in Great Lakes fish and birds as waters warm.
Warming winters may sound great at first, but they bring new problems.
The U.S. faces big drops in harvests of major food crops by 2100 if temperatures continue to rise.
Bombus affinis has plunged nearly 90 percent in abundance and distribution since the late 1990s.
A regulatory bloodbath is looming in D.C., but climate protections could advance elsewhere in 2017.
As Donald Trump takes office, here are four energy issues to watch in 2017.
European power plants could keep claiming to be green while billowing pollution from wood until 2030.
The Climate Vulnerable Forum (CVF) committed to update their climate action plans submitted as part of the U.N. climate pact.
Donald Trump could scrap the Obama administration’s plans to combat climate change once he takes office.
Weather and climate can have unexpected complex impacts on the timing and appearance of fall foliage.
This Halloween, catch up on all your spooky climate news.
Wildfires take the spotlight this week on The Shum Show. | <urn:uuid:f420cb60-6234-4f55-a670-77fc77641056> | 2.90625 | 397 | Content Listing | Science & Tech. | 59.864679 | 95,565,999 |
Researchers show deviations in an amino acid's code can occur naturally
Four letters - A, C, G and T - stand in for the four chemical bases that store information in DNA. A sequence of these same four letters, repeating in a particular order, genetically defines an organism. Within the genome sequence are shorter, three-letter codons that represent one of the 20 regularly used amino acids, with three of the possible 64 three-letter codons reserved for stop signals.
Starting from the four innermost letters and working to the outermost ring, this table shows shows which three-letter base sequence or codon encodes which amino acid. In the journal Angewandte Chemie International Ed., researchers from the US Department of Energy Joint Genome Institute (DOE JGI), a DOE Office of Science User Facility, and Yale University have discovered that microorganisms recognize more than one codon for the rare, genetically encoded amino acid selenocysteine.
Credit: Wikimedia Commons
These amino acids are the building blocks of proteins that carry out a myriad of functions. For example, the amino acid alanine can be represented by the three-letter codon GCU and the amino acid cysteine by the three-letter codon UGU. In some organisms, the three-letter codon UGA, which normally signals the end of a protein-coding gene, is hijacked to code for a rare genetically encoded amino acid called selenocysteine.
Published ahead online March 16, 2016 in the journal Angewandte Chemie International Ed., researchers from the U.S. Department of Energy Joint Genome Institute (DOE JGI), a DOE Office of Science User Facility, and Yale University have discovered that microorganisms recognize more than one codon for selenocysteine. The finding adds credence to recent studies indicating that an organism's genetic vocabulary is not as constrained as had been long held.
The work is a follow-up to two 2014 publications; a Science paper by the JGI group finding that some organisms interpret the three "stop" codons which terminate translation to mean anything but. A synthetic biology experiment of the Yale group published in an Angewandte Chemie International Ed. paper revealed the astonishing fact that almost all codons in Escherichia coli could be replaced by selenocysteine. This posed the question whether the same phenomenon can also occur in nature.
"Access to the tremendous resources at the JGI allowed us to quickly test challenging hypotheses generated from my research projects that have been supported over the long-term by DOE Basic Energy Sicences and the National Institutes of Health," said Dieter Soll, Sterling Professor of Molecular Biophysics and Biochemistry Professor of Chemistry at Yale, the lead author of the paper.
Thus a fruitful collaboration resulted; the combined team scanned trillions of base pairs of public microbial genomes and unassembled metagenome data in the National Center for Biotechnology Information and the DOE JGI's Integrated Microbial Genomes (IMG) data management system to find stop codon reassignments in bacteria and bacteriophages. Delving into genomic data from uncultured microbes afforded researchers the opportunity to learn more about how microbes behave in their natural environments, which in turn provides information on their management of the various biogeochemical cycles that help maintain the Earth.
From approximately 6.4 trillion bases of metagenomic sequence and 25,000 microbial genomes, the team identified several species that recognize the stop codons UAG and UAA, in addition to 10 sense codons, as acceptable variants for the selenocysteine codon UGA.
The findings, the team reported, "opens our minds to the possible existence of other coding schemes... Overall our approach provides new evidence of a limited but unequivocal plasticity of the genetic code whose secrets still lie hidden in the majority of unsequenced organisms."
This finding also illustrates the context-dependency of the genetic code, that accurately "reading" the code (and interpreting DNA sequences) and ultimately "writing" DNA (synthesizing sequences to carry out defined functions in bioenergy or environmental sciences) will require study of the language of DNA past the introductory course level.
This work was enabled by resources from the DOE Joint Genome Institute's Community Science Program (CSP). The CSP annual call for letters of intent are due April 7 and is focused on large-scale sequence-based genomic science projects that address questions of relevance to DOE missions in sustainable biofuel production, global carbon cycling, and biogeochemistry. For more information, see: http://bit.
David Gilbert | EurekAlert!
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
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Use this calculator to easily calculate the power of a given base, raised by a given exponent.
Exponentiation. How to calculate exponents?
Exponentiation is a mathematical operation in which a number called the base is raised to a power, which is given by the exponent. The exponent is usually written as a superscript, for example if the base is b and the exponent e the exponentiation of b by e will be be.
When the exponent is a positive integer the operation is equal to multiplying the base by itself e times. If the exponent is a negative, for example -5, the operation is 1 divided by the base raised to the absolute value of the exponent: b-5 = 1 / b5. The formula below expresses this. The most commonly computed exponents are the square of a number (b2, b raised to the second power / b to the power of two) and the cube of a number (b3, b raised to the 3-rd power / b to the power of 3), and their reverse functions: square root and cube root.
Exponents are related to logarithms so that the natural logarithm ln(e) is the inverse of the exponential function be, however defining exponentiation using logarithms is more common when dealing with complex numbers.
In combinatorics exponents express the number of possible permutations, that is - how many unique ways there are to select a part of a collection, or a set of things in which the order matters. You can use our permutation calculator for these calculations as well.
The formula for exponentiation is: where n is the exponent and b is the base. An exponent with base 0 does not technically exist, so it is not supported by our exponent calculator.
Practical application of exponents
Exponentiation has uses in economics (e.g. compound interest), biology (population growth), chemistry, physics, and, of course - computer science where storage capacity units are traditionally based off the powers of two, while public-key cryptographic functions rely on the hard reversibility of exponentiation.
In physics we have exponential decay related to light, sound, gravity, dangerous chemicals, and radiation (see radioactive decay & half-life). In marketing and the spreading of ideas, memes, viral videos, etc. we talk about exponentially increasing reach. Moore's law about the increase of computing power is in essence an exponential law. The scale for measuring Earthquakes is also exponential, so a magnitude 5 earthquake is 32 times stronger than a magnitude 4 earthquake (101.5), while a magnitude 6 earthquake releases 1,000 times more energy (103) than a 4. The decibel scale used to measure volume is also exponential: 20 dB = 102 dB = 100 power ratio, 30 dB = 103 = 1,000 power ratio, so a 30 dB sound level is 10 times louder than a 20 dB sound level.
In the graph above, you can think of each exponent as a generation (in biology), or as a tier of people who have seen a viral video or read a viral article (in marketing), or the power released from an earthquake of a magnitude equal to the exponent. As you can see by step 10 an exponential process that started with a base of 2 is completely dwarfed by one started with a base of 3 to such an extent that the base 2 line looks almost like a flat line next to the base 3 exponential curve, which is why we had to provide a zoom-in. The graph was compiled using our exponent calculator.
In complex systems exponential processes often precede cataclysmic events, such as ruptures and explosions. The distribution of work contribution, ability / talent, and wealth in humans and other species is exponential according to work often cited by the famous psychometrician Jordan B. Peterson. In the human studies circles it is known as Paretian distribution (Pareto distribution).
Financial crisis, economic crisis and bubbles have exponential nature before they pop according to Didier Sornette & colleagues . The size of cities is well predicted using power law (Zipf's Law) .
O'Boyle E.Jr., Aguinis H. (2012) "The Best and the Rest: Revisiting the Norm of Normality of Individual Performance" Personnel Psychology 65(1):79-119
Yu S., Liang J., Liu H. (2016) "Existence of Hierarchies and Human's Pursuit of Top Hierarchy Lead to Power Law" arXiv:1609.07680
D.Sornette (2009) "Dragon-Kings, Black Swans and the Prediction of Crises" International Journal of Terraspace Science and Engineering 2(1):1-18
Gabaix X. (1999) "Zipf's Law for Cities: An Explanation" The Quarterly Journal of Economics 114(3):739-767
Cite this calculator & page
If you'd like to cite this online calculator resource and information as provided on the page, you can use the following citation:
Georgiev G.Z., "Exponent Calculator", [online] Available at: https://www.gigacalculator.com/calculators/exponent-calculator.php URL [Accessed Date: 18 Jul, 2018]. | <urn:uuid:5c5030e7-9488-4383-b113-7775eff4f026> | 4.28125 | 1,092 | Knowledge Article | Science & Tech. | 47.871319 | 95,566,014 |
Practical C++ programming
Free downloading C++ tutorial in PDF
This tutorial is devoted to practical C++ programming. It teaches you the mechanics of the language, free training document under 549 designated to all level users.
Table of contents
- How to Learn C++
- Creating a simple C++ Program
- Programming Exercises
- The Elements of a Program
- Assignment Statements
- Initializing Variables
- Looping Statements
- while Statement
- Break Statement
- continue Statement
- for Statement
- switch Statement
- switch, break, and continue
- Pointers and Arrays
- Binary I/O
- Public and Private
- File Size:
- 2,782.92 Kb
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This species is known from Lombok, Sumbawa, and Flores in Indonesia. It is also known from a museum specimen from Kananggar on Sumba Island (E. Arida unpubl. data May 2017). It is a lowland species which has been found at 700 m asl (E. Arida unpubl. data May 2017).
Habitat and Ecology
This species lives in lowland dry forest and savannas in wet areas, such as marshes and streams. It presumably breeds in water as its cogeners, but there have not been any direct information on this.
It is an uncommon species. Due to ongoing decline in the quality and extent of habitat, the population is suspected to be decreasing.
Human settlements and tourist infrastructure is increasing on Flores, particularly on the western side of the island, and Lombok (Indonesian Red List Assessment Workshop May 2017). On Sumba, cattle grazing for subsistence farming is a threat to the habitat (Indonesian Red List Assessment Workshop May 2017).
This species does not occur in any protected areas.
Red List Status
Least Concern (LC)
Listed as Least Concern in view of its relatively wide distribution and presumed large population.
This species might include Hylarana elberti (D. Iskandar pers. comm.).
IUCN SSC Amphibian Specialist Group 2018. Papurana florensis. The IUCN Red List of Threatened Species 2018: e.T58598A114923441. | <urn:uuid:76237f9e-a2c6-4ff9-82fe-dc09258433a5> | 2.53125 | 323 | Knowledge Article | Science & Tech. | 55.468657 | 95,566,079 |
Scientists Warn Of Solar Storms
Scientists have warned that by the next two years, world might have to face a major power failure, and even the communication systems and satellites would have to face a major setback as a result of a huge scale sun storm.
Experts have suggested that sun in the past 10- years has reached to a position, which can be called as its peak, thus increasing the risk of Earth being hit by solar storms.
Mike Hapgood, a space weather specialist at the Rutherford Appleton Laboratory, asserted that the issue is being considered as a major concern by the governments. He further added that such incidents rarely happen, but when they do their after effects are disastrous.
He warned: “Solar storms are increasingly being put on national risk registers used for disaster planning, alongside other events like tsunamis and volcanic eruptions”.
He highlighted that there are 12% possibilities that a major storm hits the Earth after every decade, which means almost one solar storm in 100 years. Previously, such a storm was experienced 150 years back.
Major cause for the occurrence of these storms is that sun emits magnetically-charged plasma particles during coronal mass ejections. Millions of tons of such particles are emitted, which can overwhelm the planet very easily.
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The top view, taken by NASAs Hubble Space Telescope, is the first visible-light image of a dust ring around the nearby, bright young star Fomalhaut. The view at bottom points out important features in the image, such as the rings inner and outer edges. In order to image the faint ring, a coronagraph on Hubbles Advanced Camera for Surveys was used to eclipse the bright star, the position of which is indicated by a dot near the rings center. The center of the ring is about 1.4 billion miles away from the star. Astronomers believe that an unseen planet moving in an elliptical orbit is reshaping the ring.
Credit: NASA, ESA, P. Kalas and J. Graham (University of California, Berkeley), and M. Clampin (NASAs Goddard Space Flight Center)
Dusty disk around Fomalhaut makes ideal laboratory for studying planet formation
Astronomers zooming in on a nearby star with NASA’s Hubble Space Telescope have discovered unmistakable evidence of a planetary system: a perturbed dusty belt around the star that’s analogous to the vast Kuiper Belt of icy rocks encircling the sun.
While the discovery is expected to send astronomers scurrying to their telescopes to obtain direct images of a planet around the star, called Fomalhaut, it also provides a Rosetta stone for debris disks - the pancakes of rock and ice that form around new stars and coalesce into planets.
Robert Sanders | EurekAlert!
First evidence on the source of extragalactic particles
13.07.2018 | Technische Universität München
Simpler interferometer can fine tune even the quickest pulses of light
12.07.2018 | University of Rochester
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:949e08c3-38b0-4063-9b7d-cf3479a855e9> | 3.953125 | 941 | Content Listing | Science & Tech. | 41.419621 | 95,566,082 |
Survey of the Theory of Electronic Conduction in Metals
In Chapter 1 we made no mention of the detailed mechanisms that lead to electronic conduction and associated thermoelectric effects. The general phenomenological equations (1.15) and (1.16) are equally valid for metals, semiconductors, or an ionized gas, and Onsager’s relations are correct for any of these. This book is concerned, however, only with metallic conductors, and our interest in thermoelectric phenomena is based on the belief that they can shed light on fundamental features of electronic energy levels and on the interaction of conduction electrons with their environment. To see this more clearly, we must now review briefly the elements of transport theory as it applies to these materials.
KeywordsWave Vector Electronic Conduction Fermi Surface Brillouin Zone Thermoelectric Power
Unable to display preview. Download preview PDF. | <urn:uuid:941926fb-996a-4879-ae78-e2f6f29c1abd> | 2.765625 | 192 | Truncated | Science & Tech. | 28.095815 | 95,566,096 |
In the past two days, two instruments on the lander deck -- a microscope and a bake-and-sniff analyzer -- have begun inspecting soil samples delivered by the scoop on Phoenix's Robotic Arm.
"This is the first time since the Viking missions three decades ago that a sample is being studied inside an instrument on Mars," said Phoenix Principal Investigator Peter Smith of the University of Arizona, Tucson.
Stickiness of the soil at the Phoenix site has presented challenges for delivering samples, but also presents scientific opportunities. "Understanding the soil is a major goal of this mission and the soil is a bit different than we expected," Smith said. "There could be real discoveries to come as we analyze this soil with our various instruments. We have just the right instruments for the job."Images from Phoenix's Optical Microscope show nearly 1,000 separate soil particles, down to sizes smaller than one-tenth the diameter of a human hair.
At least four distinct minerals are seen.
"It's been more than 11 years since we had the idea to send a microscope to Mars and I'm absolutely gobsmacked that we're now looking at the soil of Mars at a resolution that has never been seen before," said Tom Pike of Imperial College London. He is a Phoenix co-investigator working on the lander's Microscopy, Electrochemistry and Conductivity Analyzer.
The sample includes some larger, black, glassy particles as well as smaller reddish ones. "We may be looking at a history of the soil," said Pike. "It appears that original particles of volcanic glass have weathered down to smaller particles with higher concentration of iron."
The fine particles in the soil sample closely resemble particles of airborne dust examined earlier by the microscope.
Atmospheric dust at the Phoenix site has remained about the same day-to-day so far, said Phoenix co-investigator and atmospheric scientist Nilton Renno of the University of Michigan, Ann Arbor."We've seen no major dust clouds at the landing site during the mission so far,"
Studying dust on Mars helps scientists understand atmospheric dust on Earth, which is important because dust is a significant factor in global climate change.
"We've learned there is well-mixed dust in the Martian atmosphere, much more mixed than on Earth, and that's a surprise," Renno said. Rather than particles settling into dust layers, strong turbulence mixes them uniformly from the surface to a few kilometers above the surface.
Scientists spoke at a news briefing today at the University of Arizona, where new color views of the spacecraft's surroundings were shown.
"We are taking a high-quality, 360-degree look at all of Mars that we can see from our landing site in color and stereo," said Mark Lemmon, Surface Stereo Imager lead from Texas A&M University, College Station.
"These images are important to provide the context of where the lander is on the surface. The panorama also allows us to look beyond our workspace to see how the polygon structures connect with the rest of the area. We can identify interesting things beyond our reach and then use the camera's filters to investigate their properties from afar."The Phoenix mission is led by Smith at the University of Arizona with project management at JPL and development partnership at Lockheed Martin, Denver.
International contributions come from the Canadian Space Agency; the University of Neuchatel, Switzerland; the universities of Copenhagen and Aarhus, Denmark; Max Planck Institute, Germany; and the Finnish Meteorological Institute.MEDIA CONTACTS:
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:d8980480-61d9-4533-8f3d-733ae4f95a17> | 3.4375 | 1,375 | Content Listing | Science & Tech. | 39.686752 | 95,566,101 |
In this paper, a pattern recognition technique through atmospheric turbulence is discussed. We have shown that there exists no unique relationship between the target and its power spectrum. However, for some finite number of distinguishable targets, it may be possible to recognize the targets by means of the Wiener-Khinchin's theorem. The fundamental advantage of this pattern recognition technique is the elimation of the phase distortion due to the atmospheric turbulence. However, this phase elimination also results in a loss of phase information of the target. Nevertheless, if the atmospheric turbulence is strong, this pattern recognition technique by means of Wiener-Khinchin's theorem may be more advantageous than the direct imaging method, since the phase variation will not do much good for the image formation.
F. T. S. Yu,
"Pattern Recognition Through Atmospheric Turbulence By Means Of Wiener-Khinchin's Theorem," Optical Engineering 10(1), 100118 (1 December 1971). https://doi.org/10.1117/12.7971589 | <urn:uuid:3492cbbd-baf4-4942-8a28-654b69a85343> | 2.625 | 211 | Academic Writing | Science & Tech. | 44.039352 | 95,566,102 |
During this period the moon will reach it’s full phase on Monday April 30. At that time the moon will be located opposite the sun and will lie above the horizon all night long. As the week progresses the waning gibbous moon will rise later in the evening but will still seriously impede meteor viewing as the bright glare will obscure all but the brightest meteors. The estimated total hourly meteor rates for evening observers this week is 1 as seen from mid-northern latitudes (45N) and 2 from the southern tropics (25S). For morning observers the estimated total hourly rates should be near 5 as seen from mid-northern latitudes (45N) and 8 from the southern tropics (25S). Rates during this period are reduced due to moonlight. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Note that the hourly rates listed below are estimates as viewed from dark sky sites away from urban light sources. Observers viewing from urban areas will see less activity as only the brighter meteors will be visible from such locations.
The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning April 28/29 These positions do not change greatly day to day so the listed coordinates may be used during this entire period. Most star atlases (available at science stores and planetariums) will provide maps with grid lines of the celestial coordinates so that you may find out exactly where these positions are located in the sky. A planisphere or computer planetarium program is also useful in showing the sky at any time of night on any date of the year. Activity from each radiant is best seen when it is positioned highest in the sky, either due north or south along the meridian, depending on your latitude. It must be remembered that meteor activity is rarely seen at the radiant position. Rather they shoot outwards from the radiant so it is best to center your field of view so that the radiant lies near the edge and not the center. Viewing there will allow you to easily trace the path of each meteor back to the radiant (if it is a shower member) or in another direction if it is a sporadic. Meteor activity is not seen from radiants that are located far below the horizon. The positions below are listed in a west to east manner in order of right ascension (celestial longitude). The positions listed first are located further west therefore are accessible earlier in the night while those listed further down the list rise later in the night.
These sources of meteoric activity are expected to be active this week.
Details on each source will resume next week when observing conditions are much more favorable.
|SHOWER||DATE OF MAXIMUM ACTIVITY||CELESTIAL POSITION||ENTRY VELOCITY||CULMINATION||HOURLY RATE||CLASS|
|RA (RA in Deg.) DEC||Km/Sec||Local Daylight Saving Time||North-South|
|pi Puppids (PUP)||Apr 23||07:36 (114) -46||15||18:00||<1 – <1||III|
|h Virginids (HVI)||Apr 30||13:36 (204) -11||17||00:00||<1 – <1||IV|
|Anthelion (ANT)||–||15:24 (231) -18||30||02:00||1 – 1||II|
|Lyrids (LYR)||Apr 22||18:28 (277) +34||46||05:00||<1 – <1||I|
|April rho Cygnids (AEC)||Apr 28||21:32 (323) +47||41||08:00||<1 – <1||IV|
|eta Aquariids (ETA)||May 07||22:04 (331) -04||66||08:00||1 – 2||I| | <urn:uuid:0a590832-0be0-49d1-83bc-43f229a38ada> | 2.71875 | 847 | Knowledge Article | Science & Tech. | 54.107378 | 95,566,113 |
Scores of Birds Killed During Test of Solar Project in Nevada | KCET
Scores of Birds Killed During Test of Solar Project in Nevada
A test of a solar power tower project in Nevada resulted in injuries to over one hundred birds, the federal government is reporting, though the project's owners say they've fixed the problem.
On January 14, during tests of the 110-megawatt Crescent Dunes Solar Energy Project near Tonopah, Nevada, biologists observed 130 birds entering an area of concentrated solar energy and catching fire. That's according to Rudy Evenson, Deputy Chief of Communications for Nevada Bureau of Land Management in Reno.
Evenson suggested that the birds may have been attracted by a glow the concentrated solar energy created above the project's sole tower.
The Crescent Dunes solar project, now in its final stages of construction and testing by owner SolarReserve, is set to go online in March. Its projected 110 megawatts of peak output will be sold to the utility NV Energy, which serves most of Nevada.
According to Evenson, workers testing the plant moved approximately a third of the project's ten thousand mirrors to focus sunlight on a point 1,200 feet above the ground, approximately twice the height of the power tower at Crescent Dunes.
The test started at 9:00 a.m. on January 14, Evenson told Rewire. By 10:30, biologists working on the site began noticing what have become known as "streamers," trails of smoke and water vapor caused by birds entering the field of concentrated solar energy (a.k.a. "solar flux") and igniting.
By the time the test ended for the day at 3:00 p.m., biologists had counted 130 such "streamers." A subsequent test on January 15 reduced the number of mirrors aimed at the focal point above the tower, said Evenson, and that apparently ended the injuries to birds.
SolarReserve has confirmed to Rewire that birds were injured at the plant in January, but says that the mitigation measures Evenson described have allowed subsequent testing of the plant with less risk to wildlife -- which the company is touting as good news for management of power tower wildlife issues.
"We had some avian incidents during the week of January 11, in which there were a number of incidents, estimated at under 150 avian safety issues," SolarReserve CEO Kevin Smith told Rewire. "As a result, we stopped testing until we successfully developed mitigation procedures to address the identified avian safety issues."
Those mitigation procedures, developed by SolarReserve's engineers, include repositioning the plant's mirrors to reduce the intensity of the solar flux field.
"Over the last 30 days of commissioning activities, which includes extended periods of flux (sunlight) on the tower, the Crescent Dunes project has only experienced a single (one) avian fatality attributed to the solar facility," Smith said.
Though SolarReserve may well have found a way to test and operate the Crescent Dunes plant with lower risk to wildlife, another lesson from Tonopah in January may suggest that changes at other solar power tower plants are necessary as well. Rewire has learned via anecdotal accounts from another source that at least one of the birds injured January 14 was a common raven, which -- in the words of our source -- "turned white hot and vaporized completely." Asked to confirm that report, the BLM's Evenson said that his office didn't have a list of the species affected, but added that "that's what streamers are."
The U.S.'s one other solar power plant in operation, the Ivanpah Solar Electric Generating System, has been assessing that plant's risk to birds by monitoring the number of bird carcasses found on the power plant's grounds during routine operations and periodic surveys. If solar flux from the 110-megawatt Crescent Dunes plant is indeed capable of completely incinerating a large birds such as raven, which average more than two and a half pounds, then flux at the Ivanpah plant, whose three units are each slightly greater in output than Crescent Dunes, could arguably do the same.
And that means that looking for carcasses on the ground might not tell the whole story.
For ongoing environmental coverage in March 2017 and afterward, please visit our show Earth Focus, or browse Redefine for historic material.
KCET's award-winning environment news project Redefine ran from July 2012 through February 2017.
A Q&A will immediately follow the screening with Glenn Close, Jonathan Pryce, Christian Slater, Annie Starke and director Björn Runge.
The stocks of two of the largest private prison contractors skyrocketed in the month after President Trump’s inauguration and have continued to grow.
Here are some of the coolest ways to chill out in the greater Palm Springs area.
A special ten-hour marathon revisting the best of "Visiting With Huell Howser" begins Sunday, August 5 at 10:00 a.m. on KCET.
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temperature, however, changes in a completely unexpected way: above the temperature minimum, it begins to rise to as high as 25,000 K at the top of the chromospheric
It would be difficult for us to distinguish such purposeful, nefarious camouflage from naturally occurring chromospheric
Alfvenic waves strong enough to power the solar wind.
The techniques introduced here will enable reliable and robust measurements of chromospheric
magnetic fields, shedding new light on this enigmatic but centrally important layer of the solar atmosphere.
Such a model can account for the presence of both He I and He II emission lines in the chromospheric
On Aug 8 a spectacular 'horned' dark filament graced the SE quadrant which was still present the following day, matching the alignment of chromospheric
disturbance in the SW quadrant.
They cover interior, convection, and dynamo, the formation and evolution of sunspots and active regions; flux emergence and submergence; waves, reconnection, and chromospheric
and coronal heating; magnetic fields as structuring agents of the solar atmosphere; flares, eruptions, and particle acceleration; solar wind and the interplanetary space; and Hinode and Solar Dynamics Observatory.
As this binary has a spectral classification of G4V I suggest the dip in the light curve is due to chromospheric
The heated chromospheric
matter responds by evaporating into the corona, where it can increase the gas density within a flaring loop a thousandfold.
Images with Markov Random Fields.
Starting at roughly 6,000 kelvins at the sun's surface, the solar atmosphere's temperature falls to nearly 4,300 kelvins at an altitude of 500 kilometers before rising to typical chromospheric
As the chromospheric
ribbon swept across the region signaling the reconnection of the field lines that were opened during the eruption, the same cells reappeared immediately behind the ribbon. | <urn:uuid:488c113a-f414-42e9-b08c-1b239672e0a0> | 3.40625 | 403 | Knowledge Article | Science & Tech. | 4.500918 | 95,566,126 |
Carbon is a very important chemical element, with a chemical symbol of C. All known life on Earth needs it. Carbon has atomic mass 12 and atomic number 6. It is a nonmetal, meaning that it is not a metal.
|clear (diamond) & black (graphite)|
Diamond (left) and graphite (right), the two most well-known allotropes of carbon
Spectral lines of carbon
|Name, symbol, number||carbon, C, 6|
|Group, period, block||14, 2, p|
|Standard atomic weight||12.011(1) g/mol|
|Electron configuration||[He] 2s2 2p2|
|Electrons per shell||2, 4 (Image)|
|Density (near r.t.)||amorphous: 1.8–2.1 g/cm3|
|Density (near r.t.)||diamond: 3.515 g/cm3|
|Density (near r.t.)||graphite: 2.267 g/cm3|
|Sublimation point||3915 K, 3642 °C, 6588 °F|
|Triple point||4600 K (4327°C), 10800 kPa|
|Heat of fusion||117 (graphite) kJ/mol|
|Specific heat capacity||(25 °C) 6.155 (diamond)|
8.517 (graphite) J/(mol·K)
|Oxidation states||4, 3, 2, 1, 0, −1, −2, −3, −4|
|Electronegativity||2.55 (Pauling scale)|
||1st: 1086.5 kJ/mol|
|2nd: 2352.6 kJ/mol|
|3rd: 4620.5 kJ/mol|
|Covalent radius||77(sp³), 73(sp²), 69(sp) pm|
|Van der Waals radius||170 pm|
|Crystal structure note||(diamond, clear)|
|Thermal conductivity||(300 K) 900-2300 (diamond)|
119-165 (graphite) W/(m·K)
|Thermal expansion||(25 °C) 0.8 (diamond) µm/(m·K)|
|Speed of sound (thin rod)||(20 °C) 18350 (diamond) m/s|
|Young's modulus||1050 (diamond) GPa|
|Shear modulus||478 (diamond) GPa|
|Bulk modulus||442 (diamond) GPa|
|Poisson ratio||0.1 (diamond)|
|Mohs hardness||10 (diamond)|
|CAS registry number||7440-44-0|
|Most stable isotopes|
|Main article: Isotopes of carbon|
Chemistry of carbonEdit
A whole type of Chemistry, organic chemistry, is about carbon and its compounds. Carbon makes many types of compounds. Hydrocarbons are molecules with carbon and hydrogen. Methane, Propane, and many other fuels are hydrocarbons. Many of the substances that people use daily are organic compounds.
Carbon, hydrogen, nitrogen, oxygen, and some other elements like sulfur and phosphorus together form most life on earth (see Organic chemistry and List of biologically important elements). Carbon forms a very large number of organic compounds because it can form strong bonds with itself and with other elements. Because of the amounts of carbon living things have, all organic things are considered "carbon-based". Each carbon atom can form four single covalent bonds. These bonds allow carbon to form long chain-shaped molecules, called polymers, such as plastics.
Types of carbonEdit
Carbon in nature is found in three forms called allotropes: diamond, graphite, and fullerenes. Graphite, with clay, is in pencils. It is very soft. The carbon atoms in it make rings, which are on top of each other and slide very easily. Diamonds are the hardest natural mineral. Fullerenes are a "soccer ball" shape of carbon. They are mostly of interest to science. A special, man-made, tube-shaped allotrope of carbon is the carbon nanotube. Carbon nanotubes are very hard, so they might be used in armor. Nanotubes might be useful in nanotechnology. There are 10 million known carbon compounds.
A radioactive isotope of carbon, carbon-14, can be used to figure out how old some objects are or when something died. As long as something is on the surface of the earth and taking in carbon, the amount of carbon-14 stays the same. When an object stops taking in carbon, the carbon-14 amount goes down. Because the half-life (how long it takes for half of a radioactive isotope to go away) of carbon-14 is 5730 years, scientists can see how old the object is by how much carbon-14 is left.
Where carbon isEdit
Carbon is important to the human body and other living things, and it is the second most common element in the human body, at 23% of all body weight. It is also a key part of many biological molecules (molecules used in life).
Most of the carbon on Earth is coal. Graphite is in many (typically desert) areas, including Sri Lanka, Madagascar, and Russia. Diamonds are rare and are found largely in Africa. Carbon is also in some meteorites.
- Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
- Haaland, D (1976). "Graphite-liquid-vapor triple point pressure and the density of liquid carbon". Carbon 14 (6): 357. doi:10.1016/0008-6223(76)90010-5.
- Savvatimskiy, A (2005). "Measurements of the melting point of graphite and the properties of liquid carbon (a review for 1963–2003)". Carbon 43 (6): 1115. doi:10.1016/j.carbon.2004.12.027.
- "Fourier Transform Spectroscopy of the System of CP" (PDF). Retrieved 2007-12-06.
- "Fourier Transform Spectroscopy of the Electronic Transition of the Jet-Cooled CCI Free Radical" (PDF). Retrieved 2007-12-06.
- "Carbon: Binary compounds". Retrieved 2007-12-06.
- Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.
- Properties of diamond, Ioffe Institute Database
- Emsley, John (2001). Nature's Building blocks. Oxford University Press. ISBN 0-19-850341-5. Check
|isbn=value: invalid character (help).
- University of Sheffield and Webelements Ltd. (2007). "Chemistry : Periodic Table : carbon : key information". | <urn:uuid:c50ad87e-0287-4728-9d42-cec21097ac9e> | 3.171875 | 1,536 | Knowledge Article | Science & Tech. | 74.445752 | 95,566,133 |
Concept: Physarum polycephalum
- Journal of the Royal Society, Interface / the Royal Society
- Published about 2 years ago
Several recent studies hint at shared patterns in decision-making between taxonomically distant organisms, yet few studies demonstrate and dissect mechanisms of decision-making in simpler organisms. We examine decision-making in the unicellular slime mould Physarum polycephalum using a classical decision problem adapted from human and animal decision-making studies: the two-armed bandit problem. This problem has previously only been used to study organisms with brains, yet here we demonstrate that a brainless unicellular organism compares the relative qualities of multiple options, integrates over repeated samplings to perform well in random environments, and combines information on reward frequency and magnitude in order to make correct and adaptive decisions. We extend our inquiry by using Bayesian model selection to determine the most likely algorithm used by the cell when making decisions. We deduce that this algorithm centres around a tendency to exploit environments in proportion to their reward experienced through past sampling. The algorithm is intermediate in computational complexity between simple, reactionary heuristics and calculation-intensive optimal performance algorithms, yet it has very good relative performance. Our study provides insight into ancestral mechanisms of decision-making and suggests that fundamental principles of decision-making, information processing and even cognition are shared among diverse biological systems.
Slime mould Physarum polycephalum is a single cell visible by the unaided eye. Let the slime mould span two electrodes with a single protoplasmic tube: if the tube is heated to approximately ≈40 °C, the electrical resistance of the protoplasmic tube increases from ≈3 MΩ to ≈10,000 MΩ. The organism’s resistance is not proportional nor correlated to the temperature of its environment. Slime mould can therefore not be considered as a thermistor but rather as a thermic switch. We employ the P. polycephalum thermic switch to prototype hybrid electrical analog summator, NAND gates, and cascade the gates into Flip-Flop latch. Computing operations performed on this bio-hybrid computing circuitry feature high repeatability, reproducibility and comparably low propagation delays.
Mitochondrial RNAs in the acellular slime mold Physarum polycephalum contain nucleotides that are not encoded in the mitochondrial genes from which they are transcribed. These site-specific changes are quite extensive, comprising ~4% of the residues within mRNAs and ~2% of rRNAs and tRNAs. These “extra” nucleotides are added co-transcriptionally, but the means by which this is accomplished have not been elucidated. The cox1 mRNA also contains four sites of C to U changes, which occur post-transcriptionally, most likely via targeted deamination. The currently available in vitro systems for studying P. polycephalum editing are limited in that the template is the entire ~63,000 bp mitochondrial genome. This presents a significant challenge when trying to define the signals that specify editing sites. In an attempt to overcome this issue, a method for introducing DNA into isolated P. polycephalum mitochondria via electroporation has been developed. Exogenous DNA is expressed, but the transcripts synthesized from these templates are not edited under the conditions tested. However, transcripts derived from the mitochondrial genome are accurately edited after electroporation, indicating that the editing machinery is still functional. These findings suggest that this method may ultimately provide a feasible approach to elucidating editing signals.
- Proceedings of the National Academy of Sciences of the United States of America
- Published almost 6 years ago
Spatial memory enhances an organism’s navigational ability. Memory typically resides within the brain, but what if an organism has no brain? We show that the brainless slime mold Physarum polycephalum constructs a form of spatial memory by avoiding areas it has previously explored. This mechanism allows the slime mold to solve the U-shaped trap problem-a classic test of autonomous navigational ability commonly used in robotics-requiring the slime mold to reach a chemoattractive goal behind a U-shaped barrier. Drawn into the trap, the organism must rely on other methods than gradient-following to escape and reach the goal. Our data show that spatial memory enhances the organism’s ability to navigate in complex environments. We provide a unique demonstration of a spatial memory system in a nonneuronal organism, supporting the theory that an externalized spatial memory may be the functional precursor to the internal memory of higher organisms.
In spite of the ecological importance of protists, few data are available on their distribution in soil. This investigation is the first of its kind on what could be the major components of the soil protistan community, the Myxomycetes or plasmodial slime-moulds, a monophyletic class in the phylum Amoebozoa. Myxomycetes have a complex life cycle culminating in the formation of mainly macroscopic fruiting bodies, highly variable in shape and colour, that can be found in every terrestrial biome. Despite their prevalence, they are paradoxically absent from environmental DNA sampling studies. We obtained myxomycete SSU rRNA gene sequences from soil-extracted RNAs by using specific primers. Soil samples were collected in three mountain ranges (France, Scotland and Japan). Our study revealed an unexpectedly high diversity of dark-spored Myxomycetes with the recovery of 74 phylotypes. Of these, 74 % had less than 98 % identity with known sequences, thus showing a hidden diversity; there was little overlap between localities, implying biogeographical patterns. Few phylotypes were dominant and many were unique, consistent with the “rare biosphere” phenomenon. Our study provides first detailed insight into community composition of this ecologically important group of protists, establishing means for future studies of their distribution, abundance and ecology. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd.All rights reserved.
An amoeboid unicellular organism, a plasmodium of the true slime mold Physarum polycephalum, exhibits complex spatiotemporal oscillatory dynamics and sophisticated information processing capabilities while deforming its amorphous body. We previously devised an ‘amoeba-based computer (ABC),’ that implemented optical feedback control to lead this amoeboid organism to search for a solution to the traveling salesman problem (TSP). In the ABC, the shortest TSP route (the optimal solution) is represented by the shape of the organism in which the body area (nutrient absorption) is maximized while the risk of being exposed to aversive light stimuli is minimized. The shortness of the TSP route found by ABC, therefore, serves as a quantitative measure of the optimality of the decision made by the organism. However, it remains unclear how the decision-making ability of the organism originates from the oscillatory dynamics of the organism. We investigated the number of coexisting traveling waves in the spatiotemporal patterns of the oscillatory dynamics of the organism. We show that a shorter TSP route can be found when the organism exhibits a lower number of traveling waves. The results imply that the oscillatory dynamics are highly coordinated throughout the global body. Based on the results, we discuss the fact that the decision-making ability of the organism can be enhanced not by uncorrelated random fluctuations, but by its highly coordinated oscillatory dynamics.
- Proceedings. Biological sciences / The Royal Society
- Published about 2 years ago
Learning, defined as a change in behaviour evoked by experience, has hitherto been investigated almost exclusively in multicellular neural organisms. Evidence for learning in non-neural multicellular organisms is scant, and only a few unequivocal reports of learning have been described in single-celled organisms. Here we demonstrate habituation, an unmistakable form of learning, in the non-neural organism Physarum polycephalum In our experiment, using chemotaxis as the behavioural output and quinine or caffeine as the stimulus, we showed that P. polycephalum learnt to ignore quinine or caffeine when the stimuli were repeated, but responded again when the stimulus was withheld for a certain time. Our results meet the principle criteria that have been used to demonstrate habituation: responsiveness decline and spontaneous recovery. To distinguish habituation from sensory adaptation or motor fatigue, we also show stimulus specificity. Our results point to the diversity of organisms lacking neurons, which likely display a hitherto unrecognized capacity for learning, and suggest that slime moulds may be an ideal model system in which to investigate fundamental mechanisms underlying learning processes. Besides, documenting learning in non-neural organisms such as slime moulds is centrally important to a comprehensive, phylogenetic understanding of when and where in the tree of life the earliest manifestations of learning evolved.
Self-organized mechanisms are frequently encountered in nature and known to achieve flexible, adaptive control and decision-making. Noise plays a crucial role in such systems: It can enable a self-organized system to reliably adapt to short-term changes in the environment while maintaining a generally stable behavior. This is fundamental in biological systems because they must strike a delicate balance between stable and flexible behavior. In the present paper we analyse the role of noise in the decision-making of the true slime mold Physarum polycephalum, an important model species for the investigation of computational abilities in simple organisms. We propose a simple biological experiment to investigate the reaction of P. polycephalum to time-variant risk factors and present a stochastic extension of an established mathematical model for P. polycephalum to analyze this experiment. It predicts that-due to the mechanism of stochastic resonance-noise can enable P. polycephalum to correctly assess time-variant risk factors, while the corresponding noise-free system fails to do so. Beyond the study of P. polycephalum we demonstrate that the influence of noise on self-organized decision-making is not tied to a specific organism. Rather it is a general property of the underlying process dynamics, which appears to be universal across a wide range of systems. Our study thus provides further evidence that stochastic resonance is a fundamental component of the decision-making in self-organized macroscopic and microscopic groups and organisms.
How social groups and organisms decide between alternative feeding sites or shelters has been extensively studied both experimentally and theoretically. One key result is the existence of a symmetry-breaking bifurcation at a critical system size, where there is a switch from evenly distributed exploitation of all options to a focussed exploitation of just one. Here we present a decision-making model in which symmetry-breaking is followed by a symmetry restoring bifurcation, whereby very large systems return to an even distribution of exploitation amongst options. The model assumes local positive feedback, coupled with a negative feedback regulating the flow toward the feeding sites. We show that the model is consistent with three different strains of the slime mold Physarum polycephalum, choosing between two feeding sites. We argue that this combination of feedbacks could allow collective foraging organisms to react flexibly in a dynamic environment.
Physarum Polycephalum is a single cell visible by unaided eye. This is a plasmodial, vegetative stage of acellular slime mould. This single cell has myriad of nuclei which contribute to a network of bio-chemical oscillators responsible for the slime mould’s distributed sensing, concurrent information processing and decision making, and parallel actuation. When presented with a spatial configuration of sources of nutrients, the slime mould spans the sources with networks of its protoplasmic tube. These networks belong to a family of planar proximity graphs. The protoplasmic networks also show a degree of similarity to vehicular transport networks. Previously, we have shown that the foraging behaviour of the slime mould can be applied in archaeological research to complement and enhance conventional geographic information system tools. The results produced suffered from limitation of a flat substrate: transport routes imitated by the slime mould did not reflect patterns of elevations. To overcome the limitation of the ‘flat world’ we constructed a three-dimensional model of Balkans. In laboratory experiments and computer modelling we uncovered patterns of the foraging behaviour that might shed a light onto development of Roman roads in the Balkans during the imperial period (1st century BC - 4th century AD). | <urn:uuid:23f0f575-334c-479c-b2ef-8e340fc4979f> | 2.546875 | 2,562 | Academic Writing | Science & Tech. | 13.773637 | 95,566,142 |
Asthma attacks are caused by an acute inflammatory reaction in the airways, a reaction that is largely due to actions of LTC4 synthase. For this reason asthma medicines often aim at blocking the downstream effects of LTC4 synthase. However, there is a need for new pharmaceutical alternatives, since not all patients respond to the existing medicines.
Scientists at the Department of Medical Biochemistry and Biophysics have now, with the help of the two EU networks “EICOSANOX” and “E-Mep”, elucidated the three dimensional structure of the LTC4 synthase at 2.0 Å resolution (1 Å = 1 Ångström = 10-10 m = 0,000 000 000 1 m). It is clear from the structure that the protein has three identical subunits, each of them consisting of four spiral structures that span the nuclear membrane. Also the exact position and characteristics of the active sites, where activating or blocking molecules can bind, have been identified. With this knowledge it is now possible to tailor new molecules that can block the LTC4 synthase.
The new results are also very important as they can lead the way for the development of new and more effective therapeutics against other diseases. Some 40 % of the proteins of interest for pharmaceutical developments are membrane proteins. Until now detailed structural information on these proteins has been absent, and therefore it has been difficult to fully understand their function. The present study is likely to lead the way for the determination of structures of other human membrane proteins. The elucidation of more membrane protein structures will help us understand fundamental processes that take place in the cell membranes.
Facts: Proteins consist of a chain of amino acids. The length of this chain can range from a few to thousands of amino acids. The chain is then folded in a characteristic way and the 3-D structure can bind different molecules. Determining a protein structure and its biochemical characteristics helps us understand its function, and to design blocking or activating molecules which can serve as medicines. A known protein structure therefore makes it easier and faster to develop new pharmaceuticals.
The EU network EICOSANOX brings together leading scientists from Europe and Canada, and is coordinated by Karolinska Institutet.
Nature, AOP 15 July 2007
Katarina Sternudd | alfa
Scientists uncover the role of a protein in production & survival of myelin-forming cells
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
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Last updated February 8, 2018 at 10:38 am
The robot revolution is coming, here’s what needs to be tackled first.
Robotics will be one of the biggest changes to the way that we live and operate in the future, and it’s rapidly approaching. With the power to completely revolutionise science, medicine, manufacturing, exploration and our day to day lives, the next decade will be an incredibly exciting time to live through.
However, there are a number of challenges we will need to overcome first, technically, socially and ethically.
The journal Science Robotics ran a public survey of the unsolved challenges in robotics. An invited panel of experts then sifted through the responses to come up with 10 grand challenges that the field will encounter in the foreseeable future.
Seven of these challenges are technologies that will have an impact on all applications of robotics – including creating new materials and manufacturing methods, developing cost-effective and long-lasting power sources for mobile robots, and programming artificial intelligence to perform deep moral and social reasoning about real-world problems.
Two challenges represent key example applications of robotics – medical and social – which involve extensive human interaction and encounter their own unique sets of issues in sensing, perception and intelligence.
The final challenge is addressing ethics and security issues of integrating robots into society.
1. New materials and fabrication
The next generation of robots will need to be multifunctional, power-efficient, compliant and autonomous in ways similar to a biological organism.
While gears and electromechanical actuators are fundamental to the operation of many robots today, in the future new materials and ways of controlling movement will be required. One approach taken by labs around the world are artificial muscles, while others are thinking about advanced manufacturing and assembly strategies.
Artificial muscles are more or less exactly what they sound like, materials which act in a way which mimics biological muscle. However, using softer materials to get this pliability comes with the trade-off of lower strength compared to rigid construction. They operate through the shrinkage or expansion of the material, however that does in turn limit their strength. In an effort to solve this problem, labs are already working on ways to make them stronger.
One other advantage of soft construction and artificial muscles is the potential to make them self-healing in the case of damage.
One other advance which is being worked on at the moment is looking at the very construction of robotics themselves. Rather than a nuts-and-bolts approach to assembly, the next generation of robotics will need to incorporate dissimilar materials in ways they can work together. For example, rigid and soft materials, or conductive and dielectric materials may need to be layered together, or incorporated into a single body, the same way our bodies layer and integrate tissues with different properties (eg muscles and bone).
An advantage of this approach is being able to layer sensors and actuators in a way where they can work together more effectively and efficiently.
2. Bioinspired and biohybrid robots
More and more, robotics engineers are looking to nature for inspiration when it comes to design rules to build a robot that performs like a natural system.
One step even further than taking that inspiration is a biohybrid, which incorporates biological material in its design.
The biggest challenges that need to be overcome include developing a battery that can match a metabolic energy source of a living organism, muscle-like actuators, self-healing materials, and autonomy in different environments.
The biggest bottlenecks to see true bioinspired/biohybrid robots exist in the movement and energy sources.
Electromagnetic motors are useful for large robots, but inefficient when scaled down or in soft systems. Similarly, artificial muscle has the limitations above.
No battery can yet match a biological metabolism for energy generation, which likewise limits their size. However if artificial muscles can be developed further, scaling robotic sizes down may minimise this limitation.
3. Power and Energy
Like all electric systems, power sources are one of the major limitations for robotics.
In practice, the usefulness of a mobile, autonomous robot is largely dictated by its battery’s power, size and weight. A battery with long longevity will be large and heavy, but a small battery will have a limited lifespan.
To minimise these limitations work is ongoing into making the components of a robot more power efficient.
However, another approach could be to make an autonomous robot able to extract energy from its surroundings, such as light, vibrations, and mechanical movement.
Battery technology will also likely need to improve beyond the nickel-metal hydride and lithium ion options currently available. Research is already ongoing into next generation options such as fuel cells and supercapacitors.
Making these energy harvesting and storage options stable in different environments will also be a challenge. Deep sea exploration robots require compact, stable and high-energy density batteries. A flying robot would require a lightweight, tolerant to temperature solutions. As a result, it is unlikely one solution will cover all applications, and each will need to be developed individually.
4. Robot swarms
Robot swarms are a different take on tackling a task requiring a large robot – allowing simpler, less expensive modular robotic units to be configured into a team.
It is an approach very much inspired by nature, where a single animal can’t achieve a goal by itself, so instead coordinate with others to complete the task.
This approach however not only takes coordination with others, but also sensing the environment, the other animals around it, and communication within the team, while in effect acting independently on its role in the task.
As sensors, processors, and communication devices get cheaper and increase in performance, with a reduction in size, the development of swarm robot strategies will increase over the next decade.
5. Navigation and exploration
Robotics has moved ahead in leaps and bounds in navigation and exploration, with autonomous robots advancing rapidly thanks to developments in path planning, obstacle avoidance and environment mapping.
However, the challenges will only increase as we use robots more and more to explore hostile places.
In the future, robots will be required to operate in environments that are not only undiscovered, but that the very nature of the environment is not well understood.
For example, robots in underground environments must cope with rough terrain, narrow confines and hampered light and communication. Robots in nuclear power plants will need to cope with high levels of radiation and restricted space. Meanwhile robots exploring other planets will need to deal with an environment which is unknown and unmapped, with the added challenge of long delays with communication.
In all of these scenarios, resilient navigation systems which are capable of sensing, mapping, understanding and reacting to its surrounds autonomously will be vital.
The exploration robots of the future will also need to be able to handle failures, and adapt its function to suit. Additionally, they’ll need to develop innate abilities to recognise new discoveries, and use that new knowledge to continue its task.
6. AI for robotics
Many of the challenges of the future will require the continued development of artificial intelligence.
Already robots are capable of object recognition using pattern recognition. However, while these fulfil one narrow aspect of intelligence, there is still a long way to go to replicate and exceed all the types of intelligence we see in humans and other animals.
To achieve this, scientists will need to create a comprehensive map of the key mechanisms of human intelligence, and recreate that into a software system.
7. Brain-computer interfaces
Brain-computer interfaces are a direct connection between brain and machine, allowing the machine to be controlled by direct thought.
Using BCI’s, we could in the future augment human ability, and, more importantly, restore function to patients with reduced capabilities. Restoring movement for paralysed people, controlling prostheses, and restoring neural function following strokes and other neurological injuries, are all occurring now in some form.
The challenge in the future however will be developing the technology to allow wider adoption Equipment for sensing of brain signals is currently expensive cumbersome, however work in happening into implantable microsensors with flexible electronics, ultra-low power needs, and wireless data.
Another challenge surrounds the processing of that data being collected. The folding and function of the brain’s cortex differs between people, making processing of signals an individually tailored requirement. Currently, long period of training, calibration and learning are required.
8. Social interaction
Social interaction is one of the most complex of human behaviours. However, it is one that because we’re so adept at recognising and interpreting social behaviour and norms, we underestimate its actual complexity.
There is so much nuance, rapid changes and unconscious social cues that we innately pick up, that it is argued our understanding of human social interaction is less understood than Newtonian mechanics or even human visual perception.
Social signals are also very context-dependent, and vary depending on cultures. Robots would not only need to pick up the social cues being displayed, but also adapt to cultural differences and learn an appropriate response to the setting.
Emotional responses, such as empathy, are another challenge for robots to understand and display as appropriate.
An added challenge is to be able to maintain solutions for these over a long-term period. At the moment most social robots are designed and programmed for short interactions with humans lasting minutes or hours at most. However, as robots become more integrated into society, the timescale of these interactions increases to become years. The social programming of a robot will need to expand from moment-to-moment engagements to being able to form and maintain long-term relationships.
9. Medical robotics
One of the fields where robotics will have its biggest impact will be medicine, improving healthcare and reducing cost.
One of the biggest challenges will be moving towards systems which show greater and greater levels of autonomy.
Where autonomous robots operate currently usually involves product manufacturing and similar roles which have been tailored to suit the robot’s capabilities. However, in medicine, the situation is always changing, uncontrolled and unique from patient to patient.
As a result, the robotics used today are usually focussed on enhancing the skills of a surgeon, where input is provided by a surgeon, which is carried out more precisely by the robot than is possible by human hand.
One potential for increased robotic use is having one surgeon supervise a set of robots who carried our certain tasks autonomously, but call upon the surgeon to take over during critical, patient-specific steps.
Moving away from surgery, implantable miniaturized multifunctional devices are being developed. These would be implanted long-term, monitoring and potentially intervening in medical episodes as they happen. However, these devices require long-term power availability, and also face the challenge of biocompatibility – being compatible with the body and not causing issues themselves. Additionally, they would need to detect and respond autonomously to all possible failures within the device itself.
Micro- or nano-robots which swarm through the patient’s body are another possibility being explored. However these robots would need to be biodegradable but non toxic, plus have the ability to target the diseased location and deliver a meaningful therapy.
10. Robot ethics and security
The potential regulatory, ethical and legal barriers facing the increased use of autonomous robots are some of the most important challenges facing the field.
In particular, there were 5 issues identified.
Firstly, excessive reliance on robotics could see sensitive tasks which should require a human guide at least supervising the task, being delegated entirely to AI.
Robotics and AI could see an increase in humans not taking responsibility for failures. Instead, responsibility is needed to be distributed in a different way.
Unemployment could well become a major factor in the roll out of increased robotics. A change in the workplace structure, a shift in skills requirements, and a potential deskilling of a workforce, are all possible in the near future. However, ethicists say this would be irresponsible, especially in safety-critical uses. Pilots should continue landing planes so that they are still able to should the AI be incapable, and radiologists should keep studying images to prevent deskilling in case the AI fails. Maintaining a skill base will remain critical.
Increased unemployment is probably inevitable however, with reports of 400 to 800 million jobs being at risk from AI. A shift in society expectations is critical in this scenario, where the financial benefits of this huge transformation are shared with those adversely affected, lowering inequality.
Fourth, AI is at risk of eroding human freedom. Rather than allowing humans to head in our own direction, human behaviour could need to change to accommodate automation.
Finally, one of the major risks is straight-out misuse. A very human problem, there is nevertheless the potential for AI to be misused in unethical ways. Some ethicists say that to minimise this chance, AI needs to be designed and used to treat every human being as an end, and never only as a means.
Robotics and AI is coming, and within our lifetimes will make a seismic shift to society. By tackling these 10 challenges, we will maximise the opportunities available to use, and hopefully, minimise the downsides to the coming robotic revolution. However, many of the problems we face are human, not technological, but likewise the solutions are also human, not technological. The future will be what we will make it.
Read more at Science Robotics | <urn:uuid:da149eea-bce3-4f31-9c48-d2bf2d8bfad6> | 3.375 | 2,752 | Listicle | Science & Tech. | 24.631561 | 95,566,189 |
Cross Sections and Rate Constants
In order to describe in a quantitative way the phenomena discussed in the previous chapter, we need to be able to calculate or measure the required cross sections or rate constants. To begin the discussion, we divide collisions into two classes: elastic collisions (scattering) during which the particles interact (collide) with each other but only their directions of motion and speeds change, and inelastic collisions in which both the motion and the internal energies of the particles are changed. In Table 2.1 are given examples of inelastic collisions which we will consider in this text. Although inelastic collisions are clearly more interesting, we start by discussing experiments which only determine whether or not a particle was deflected.
KeywordsImpact Parameter Differential Cross Section Inelastic Collision Incident Particle Target Atom
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Effects of Neighboring Atoms in Molecules or Solids
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Classical Deflection Function Expressions
- J. Lindhard, V. Nielsen, and M. Scharff, K. Dan. Vidensk. Selsk. Mat. Fys. Medd., 36 (10) (1968).Google Scholar | <urn:uuid:73b05e59-02bb-48e9-8a2a-35563df0029f> | 3.328125 | 511 | Academic Writing | Science & Tech. | 58.863935 | 95,566,214 |
Concerns about anthropogenic climate change have resulted in promotion of renewable energy sources, especially wind energy. A concern raised against widespread windfarm development is that it may negatively impact bird populations as a result of bird collision with turbines, habitat loss and disturbance. Using systematic review methodology bird abundance data were synthesized from 19 globally-distributed windfarms using meta-analysis. The effects of bird taxon, turbine number, power, location, latitude, habitat type, size of area, time since operation, migratory status of the species and quality of evidence were analysed using meta-regression. Although the synthesized data suggest a significant negative impact of windfarms on bird abundance, there is considerable variation in the impact of individual windfarm sites on individual bird species, and it is unclear if the negative impact is a decline in population abundance or a decline in use owing to avoidance. Anseriformes experienced greater declines in abundance than other taxa, followed by Charadriiformes, Falconiformes and Accipitriformes, and Passeriformes. Time since windfarms commenced operation also had a significant impact on bird abundance, with longer operating times resulting in greater declines in abundance than short operating times. Other variables, including turbine number and turbine power either had very weak but statistically significant effects or did not have a significant effect on bird abundance. Windfarms may have significant biological impacts, especially over longer time scales, but the evidence-base is poor, with many studies being methodologically weak, and more long-term impact assessments are required. There is clear evidence that Anseriformes (wildfowl) and Charadriiformes (waders) experience declines in abundance, suggesting that a precautionary approach should be adopted to windfarm development near aggregations of these taxa in offshore and coastal locations. The impact of windfarm developments on bird populations must also be viewed in the context of the possible impact of climate change in the absence of windfarms.
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* Views captured on Cambridge Core between September 2016 - 17th July 2018. This data will be updated every 24 hours. | <urn:uuid:bf1339e5-a79f-4d0b-9b4b-87bf014b0cba> | 3.40625 | 446 | Truncated | Science & Tech. | -0.451471 | 95,566,232 |
London: Huge volumes of ice, buried under the Phlegra Montes mountain range on Mars could be a source of water for future astronauts, researchers say.
Phlegra Montes is a range of gently curving mountains and ridges on Mars.
It extends from the northeastern portion of the Elysium volcanic province to the northern lowlands, spanning latitudes from roughly 30°N to 50°N.
According to European Space Society, the mountains themselves are probably not volcanic in origin, but have been raised by ancient tectonic forces that squeezed different regions of the surface together.
New images from the high-resolution stereo camera on ESA’s Mars Express orbiter allow a closer inspection and show that almost every mountain is surrounded by ‘lobate debris aprons’ – curved features typically observed around plateaus and mountains at these latitudes.
Previous studies have shown that this material appears to have moved down the mountain slopes over time, and looks similar to the debris found covering glaciers here on Earth.
The suggestion then is that there may be glaciers buried just below the surface in this region.
This interpretation is backed by the radar on NASA’s Mars Reconnaissance Orbiter looking beneath the Martian surface.
The radar shows that ‘lobate debris aprons’ are indeed strongly associated with the presence of water ice, perhaps only 20 m down.
Further evidence for relatively recent glaciation can be seen inside impact craters in the region. Series of ridges are thought to have developed when the ancient craters filled with snow. Over time, the snow compacted to form glaciers, which then sculpted the crater floors.
There are yet more glacial flow patterns visible in the valley at the centre of the image.
It is believed that mid-latitude glaciers developed at various times in the last several hundred million years, when the polar axis of Mars was significantly different from today, leading to quite different climatic conditions.
All of this points to plentiful water ice just below the surface in Phlegra Montes. If this proves to be true, such ice fields could provide future astronauts with a source of water on the Red Planet. | <urn:uuid:e430d118-abd0-481a-8de2-eb829a945f9d> | 4.15625 | 446 | News Article | Science & Tech. | 35.974318 | 95,566,264 |
Polynomials and polynomial functions . Standard Form. Polynomial Function is classified by degree. Its degree is the highest degree among its monomial term(s). The degree determines the possible number of turning points in the graph and the end behavior of the graph.
n ≥ 1, then P(x) = 0 has exactly n roots. This includes multiple and complex roots. | <urn:uuid:88fb60bf-1e5f-42d5-bca7-cd7700ab09c2> | 2.75 | 79 | Knowledge Article | Science & Tech. | 68.607759 | 95,566,306 |
Keratin derives from Greek κερατίνη keratíni from κέρας keras (genitive κέρατος keratos) meaning "horn" originating from the Proto-Indo-European *ḱer- of the same meaning. It is composed of "horn like", i.e., kerato, to which the chemical suffix -in is appended. The Greek keras is used in many animal names, e.g. Rhinoceros, meaning "nose with a horn".
Keratin filaments are abundant in keratinocytes in the cornified layer of the epidermis; these are proteins which have undergone keratinization. In addition, keratin filaments are present in epithelial cells in general. For example, mouse thymic epithelial cells (TECs) are known to react with antibodies for keratin 5, keratin 8, and keratin 14. These antibodies are used as fluorescent markers to distinguish subsets of TECs in genetic studies of the thymus.
Keratins (also described as cytokeratins) are polymers of type I and type II intermediate filaments, which have only been found in the genomes of chordates (vertebrates, Amphioxus, urochordates). Nematodes and many other non-chordate animals seem to only have type VI intermediate filaments, lamins, which have a long rod domain (vs. a short rod domain for the keratins).
The human genome encodes 54 functional keratin genes which are located in two clusters on chromosomes 12 and 17. This suggests that they have originated from a series of gene duplications on these chromosomes.
The keratins include the following proteins of which KRT23, KRT24, KRT25, KRT26, KRT27, KRT28, KRT31, KRT32, KRT33A, KRT33B, KRT34, KRT35, KRT36, KRT37, KRT38, KRT39, KRT40, KRT71, KRT72, KRT73, KRT74, KRT75, KRT76, KRT77, KRT78, KRT79, KRT8, KRT80, KRT81, KRT82, KRT83, KRT84, KRT85 and KRT86 have been used to describe keratins past 20.
The first sequences of keratins were determined by Hanukoglu and Fuchs. These sequences revealed that there are two distinct but homologous keratin families which were named as Type I keratin and Type II keratins. By analysis of the primary structures of these keratins and other intermediate filament proteins, Hanukoglu and Fuchs suggested a model that keratins and intermediate filament proteins contain a central ~310 residue domain with four segments in α-helical conformation that are separated by three short linker segments predicted to be in beta-turn conformation. This model has been confirmed by the determination of the crystal structure of a helical domain of keratins. | <urn:uuid:70e8cc90-97c9-4b9c-ab28-29c17d8a2c7b> | 3.40625 | 667 | Knowledge Article | Science & Tech. | 41.074524 | 95,566,327 |
Rings of Neptune
The rings of Neptune consist primarily of five principal rings and were first discovered (as "arcs") in 1984 in Chile by Patrice Bouchet, Reinhold Häfner and Jean Manfroid at La Silla Observatory (ESO) during an observing program proposed by André Brahic and Bruno Sicardy from Paris Observatory, and at Cerro Tololo Interamerican Observatory by F. Vilas and L.-R. Elicer for a program led by William Hubbard. They were eventually imaged in 1989 by the Voyager 2 spacecraft. At their densest, they are comparable to the less dense portions of Saturn's main rings such as the C ring and the Cassini Division, but much of Neptune's ring system is quite tenuous, faint and dusty, more closely resembling the rings of Jupiter. Neptune's rings are named after astronomers who contributed important work on the planet: Galle, Le Verrier, Lassell, Arago, and Adams. Neptune also has a faint unnamed ring coincident with the orbit of the moon Galatea. Three other moons orbit between the rings: Naiad, Thalassa and Despina.
The rings of Neptune are made of extremely dark material, likely organic compounds processed by radiation, similar to that found in the rings of Uranus. The proportion of dust in the rings (between 20% and 70%) is high, while their optical depth is low to moderate, at less than 0.1. Uniquely, the Adams ring includes five distinct arcs, named Fraternité, Égalité 1 and 2, Liberté, and Courage. The arcs occupy a narrow range of orbital longitudes and are remarkably stable, having changed only slightly since their initial detection in 1980. How the arcs are stabilized is still under debate. However, their stability is probably related to the resonant interaction between the Adams ring and its inner shepherd moon, Galatea.
Discovery and observations
The first mention of rings around Neptune dates back to 1846 when William Lassell, the discoverer of Neptune's largest moon, Triton, thought he had seen a ring around the planet. However, his claim was never confirmed and it is likely that it was an observational artifact. The first reliable detection of a ring was made in 1968 by stellar occultation, although that result would go unnoticed until 1977 when the rings of Uranus were discovered. Soon after the Uranus discovery, a team from Villanova University led by Harold J. Reitsema began searching for rings around Neptune. On 24 May 1981, they detected a dip in a star's brightness during one occultation; however, the manner in which the star dimmed did not suggest a ring. Later, after the Voyager fly-by, it was found that the occultation was due to the small Neptunian moon Larissa, a highly unusual event.
In the 1980s, significant occultations were much rarer for Neptune than for Uranus, which lay near the Milky Way at the time and was thus moving against a denser field of stars. Neptune's next occultation, on 12 September 1983, resulted in a possible detection of a ring. However, ground-based results were inconclusive. Over the next six years, approximately 50 other occultations were observed with only about one-third of them yielding positive results. Something (probably incomplete arcs) definitely existed around Neptune, but the features of the ring system remained a mystery. The Voyager 2 spacecraft made the definitive discovery of the Neptunian rings during its fly-by of Neptune in 1989, passing by as close as 4,950 km (3,080 mi) above the planet's atmosphere on 25 August. It confirmed that occasional occultation events observed before were indeed caused by the arcs within the Adams ring (see below). After the Voyager fly-by the previous terrestrial occultation observations were reanalyzed yielding features of the ring's arcs as they were in 1980s, which matched those found by Voyager 2 almost perfectly.
Since Voyager 2's fly-by, the brightest rings (Adams and Le Verrier) have been imaged with the Hubble Space Telescope and Earth-based telescopes, owing to advances in resolution and light-gathering power. They are visible, slightly above background noise levels, at methane-absorbed wavelengths in which the glare from Neptune is significantly reduced. The fainter rings are still far below the visibility threshold.
Neptune possesses five distinct rings named, in order of increasing distance from the planet, Galle, Le Verrier, Lassell, Arago and Adams. In addition to these well-defined rings, Neptune may also possess an extremely faint sheet of material stretching inward from the Le Verrier to the Galle ring, and possibly farther in toward the planet. Three of the Neptunian rings are narrow, with widths of about 100 km or less; in contrast, the Galle and Lassell rings are broad—their widths are between 2,000 and 5,000 km. The Adams ring consists of five bright arcs embedded in a fainter continuous ring. Proceeding counterclockwise, the arcs are: Fraternité, Égalité 1 and 2, Liberté, and Courage. The first three names come from "liberty, equality, fraternity", the motto of the French Revolution and Republic. The terminology was suggested by their original discoverers, who had found them during stellar occultations in 1984 and 1985. Four small Neptunian moons have orbits inside the ring system: Naiad and Thalassa orbit in the gap between the Galle and Le Verrier rings; Despina is just inward of the Le Verrier ring; and Galatea lies slightly inward of the Adams ring, embedded in an unnamed faint, narrow ringlet.
The Neptunian rings contain a large quantity of micrometer-sized dust: the dust fraction by cross-section area is between 20% and 70%. In this respect they are similar to the rings of Jupiter, in which the dust fraction is 50%–100%, and are very different from the rings of Saturn and Uranus, which contain little dust (less than 0.1%). The particles in Neptune's rings are made from a dark material; probably a mixture of ice with radiation-processed organics. The rings are reddish in color, and their geometrical (0.05) and Bond (0.01–0.02) albedos are similar to those of the Uranian rings' particles and the inner Neptunian moons. The rings are generally optically thin (transparent); their normal optical depths do not exceed 0.1. As a whole, the Neptunian rings resemble those of Jupiter; both systems consist of faint, narrow, dusty ringlets and even fainter broad dusty rings.
The rings of Neptune, like those of Uranus, are thought to be relatively young; their age is probably significantly less than that of the Solar System. Also, like those of Uranus, Neptune's rings probably resulted from the collisional fragmentation of onetime inner moons. Such events create moonlet belts, which act as the sources of dust for the rings. In this respect the rings of Neptune are similar to faint dusty bands observed by Voyager 2 between the main rings of Uranus.
The innermost ring of Neptune is called the Galle ring after Johann Gottfried Galle, the first person to see Neptune through a telescope (1846). It is about 2,000 km wide and orbits 41,000–43,000 km from the planet. It is a faint ring with an average normal optical depth of around 10−4,[a] and with an equivalent depth of 0.15 km.[b] The fraction of dust in this ring is estimated from 40% to 70%.
The next ring is named the Le Verrier ring after Urbain Le Verrier, who predicted Neptune's position in 1846. With an orbital radius of about 53,200 km, it is narrow, with a width of about 113 km. Its normal optical depth is 0.0062 ± 0.0015, which corresponds to an equivalent depth of 0.7 ± 0.2 km. The dust fraction in the Le Verrier ring ranges from 40% to 70%. The small moon Despina, which orbits just inside of it at 52,526 km, may play a role in the ring's confinement by acting as a shepherd.
The Lassell ring, also known as the plateau, is the broadest ring in the Neptunian system. It is the namesake of William Lassell, the English astronomer who discovered Neptune's largest moon, Triton. This ring is a faint sheet of material occupying the space between the Le Verrier ring at about 53,200 km and the Arago ring at 57,200 km. Its average normal optical depth is around 10−4, which corresponds to an equivalent depth of 0.4 km. The ring's dust fraction is in the range from 20% to 40%.
There is a small peak of brightness near the outer edge of the Lassell ring, located at 57,200 km from Neptune and less than 100 km wide, which some planetary scientists call the Arago ring after François Arago, a French mathematician, physicist, astronomer and politician. However, many publications do not mention the Arago ring at all.
The outer Adams ring, with an orbital radius of about 63,930 km, is the best studied of Neptune's rings. It is named after John Couch Adams, who predicted the position of Neptune independently of Le Verrier. This ring is narrow, slightly eccentric and inclined, with total width of about 35 km (15–50 km), and its normal optical depth is around 0.011 ± 0.003 outside the arcs, which corresponds to the equivalent depth of about 0.4 km. The fraction of dust in this ring is from 20% to 40%—lower than in other narrow rings. Neptune's small moon Galatea, which orbits just inside of the Adams ring at 61,953 km, acts like a shepherd, keeping ring particles inside a narrow range of orbital radii through a 42:43 outer Lindblad resonance. Galatea's gravitational influence creates 42 radial wiggles in the Adams ring with an amplitude of about 30 km, which have been used to infer Galatea's mass.
The brightest parts of the Adams ring, the ring arcs, were the first elements of Neptune's ring system to be discovered. The arcs are discrete regions within the ring in which the particles that it comprises are mysteriously clustered together. The Adams ring is known to comprise five short arcs, which occupy a relatively narrow range of longitudes from 247° to 294°.[c] In 1986 they were located between longitudes of:
- 247–257° (Fraternité),
- 261–264° (Égalité 1),
- 265–266° (Égalité 2),
- 276–280° (Liberté),
- 284.5–285.5° (Courage).
The brightest and longest arc was Fraternité; the faintest was Courage. The normal optical depths of the arcs are estimated to lie in the range 0.03–0.09 (0.034 ± 0.005 for the leading edge of Liberté arc as measured by stellar occultation); the radial widths are approximately the same as those of the continuous ring—about 30 km. The equivalent depths of arcs vary in the range 1.25–2.15 km (0.77 ± 0.13 km for the leading edge of Liberté arc). The fraction of dust in the arcs is from 40% to 70%. The arcs in the Adams ring are somewhat similar to the arc in Saturn's G ring.
The highest resolution Voyager 2 images revealed a pronounced clumpiness in the arcs, with a typical separation between visible clumps of 0.1° to 0.2°, which corresponds to 100–200 km along the ring. Because the clumps were not resolved, they may or may not include larger bodies, but are certainly associated with concentrations of microscopic dust as evidenced by their enhanced brightness when backlit by the Sun.
The arcs are quite stable structures. They were detected by ground-based stellar occultations in the 1980s, by Voyager 2 in 1989 and by Hubble Space Telescope and ground-based telescopes in 1997–2005 and remained at approximately the same orbital longitudes. However some changes have been noticed. The overall brightness of arcs decreased since 1986. The Courage arc jumped forward by 8° to 294° (it probably jumped over to the next stable co-rotation resonance position) while the Liberté arc had almost disappeared by 2003. The Fraternité and Égalité (1 and 2) arcs have demonstrated irregular variations in their relative brightness. Their observed dynamics is probably related to the exchange of dust between them. Courage, a very faint arc found during the Voyager flyby, was seen to flare in brightness in 1998; it was back to its usual dimness by June 2005. Visible light observations show that the total amount of material in the arcs has remained approximately constant, but they are dimmer in the infrared light wavelengths where previous observations were taken.
The arcs in the Adams ring remain unexplained. Their existence is a puzzle because basic orbital dynamics imply that they should spread out into a uniform ring over a matter of years. Several theories about the arcs' confinement have been suggested, the most widely publicized of which holds that Galatea confines the arcs via its 42:43 co-rotational inclination resonance (CIR).[d] The resonance creates 84 stable sites along the ring's orbit, each 4° long, with arcs residing in the adjacent sites. However measurements of the rings' mean motion with Hubble and Keck telescopes in 1998 led to the conclusion that the rings are not in CIR with Galatea.
A later model suggested that confinement resulted from a co-rotational eccentricity resonance (CER).[e] The model takes into account the finite mass of the Adams ring, which is necessary to move the resonance closer to the ring. A byproduct of this theory is a mass estimate for the Adams ring—about 0.002 of the mass of Galatea. A third theory proposed in 1986 requires an additional moon orbiting inside the ring; the arcs in this case are trapped in its stable Lagrangian points. However Voyager 2's observations placed strict constraints on the size and mass of any undiscovered moons, making such a theory unlikely. Some other more complicated theories hold that a number of moonlets are trapped in co-rotational resonances with Galatea, providing confinement of the arcs and simultaneously serving as sources of the dust.
The rings were investigated in detail during the Voyager 2 spacecraft's flyby of Neptune in August 1989. They were studied with optical imaging, and through observations of occultations in ultraviolet and visible light. The spaceprobe observed the rings in different geometries relative to the Sun, producing images of back-scattered, forward-scattered and side-scattered light.[f] Analysis of these images allowed derivation of the phase function (dependence of the ring's reflectivity on the angle between the observer and Sun), and geometrical and Bond albedo of ring particles. Analysis of Voyager's images also led to discovery of six inner moons of Neptune, including the Adams ring shepherd Galatea.
|Ring name||Radius (km)||Width (km)||Eq. depth (km)[b][g]||N. Opt. depth[a]||Dust fraction,%||Ecc.||Incl.(°)||Notes|
|Galle (N42)||40,900–42,900||2,000||0.15||~ 10−4||40–70||?||?||Broad faint ring|
|Le Verrier (N53)||53,200 ± 20||113||0.7 ± 0.2||6.2 ± 1.5 × 10–3||40–70||?||?||Narrow ring|
|Lassell||53,200–57,200||4,000||0.4||~ 10−4||20–40||?||?||Lassell ring is a faint sheet of material stretching from Le Verrier to Arago|
|Adams (N63)||62,932 ± 2||15–50||0.4
1.25–2.15 (in arcs)
|0.011 ± 0.003
0.03–0.09 (in arcs)
40–70 (in arcs)
|4.7 ± 0.2 × 10–4||0.0617 ± 0.0043||Five bright arcs|
*A question mark means that the parameter is not known.
- The normal optical depth τ of a ring is the ratio of the total geometrical cross-section of the ring's particles to the area of the ring. It assumes values from zero to infinity. A light beam passing normally through a ring will be attenuated by the factor e–τ.
- The equivalent depth ED of a ring is defined as an integral of the normal optical depth across the ring. In other words ED = ∫τdr, where r is radius.
- The longitude system is fixed as of 18 August 1989. The zero point corresponds to the zero meridian on Neptune.
- The corotation inclination resonance (CIR) of the order m between a moon on inclined orbit and a ring occurs if the pattern speed of the perturbing potential (from a moon) equals the mean motion of the ring particles . In other words the following condition should be met , where and are the nodal precession rate and mean motion of the moon, respectively. CIR supports 2m stable sites along the ring.
- The corotation eccentricity resonance (CER) of the order m between a moon on eccentric orbit and a ring occurs if the pattern speed of the perturbing potential (from a moon) equals the mean motion of the ring particles . In other words the following condition should be met , where and are the apsidal precession rate and mean motion of the moon, respectively. CER supports m stable sites along the ring.
- Forward-scattered light is light scattered at a small angle relative to solar light. Back-scattered light is light scattered at an angle close to 180° (backwards) relative to solar light. The scattering angle is close to 90° for side-scattered light.
- The equivalent depth of Galle and Lassell rings is a product of their width and the normal optical depth.
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Coefficient of Conservatism:
Coefficient of Wetness:
Disturbed forests and forest edges.
This Eurasian species, first collected in Emmet Co. in 2007 by K. Gyekis, is very locally frequent in some parts of Ontario, and can be expected to increase its range. It is quite like C. arctata in appearance, but forms dense, large clumps and lacks the reddish purple bases of C. arctata (and all other species of sect. Hymenochlaenae, except for the distinctive C. sprengelii). The perigynia are very persistent and can be seen on the plants as late as early November; unlike other, similar Michigan species. | <urn:uuid:f721df3f-bb38-4f97-9390-03e4fd435d63> | 2.5625 | 151 | Knowledge Article | Science & Tech. | 50.132898 | 95,566,333 |
Tomographic model indicates Southern Tibet formed within 10 million years
Using seismic data and supercomputers, Rice University geophysicists have conducted a massive seismic CT scan of the upper mantle beneath the Tibetan Plateau and concluded that the southern half of the "Roof of the World" formed in less than one-quarter of the time since the beginning of India-Eurasia continental collision.
The research, which appears online this week in the journal Nature Communications, finds that the high-elevation of Southern Tibet was largely achieved within 10 million years. Continental India's tectonic collision with Asia began about 45 million years ago.
"The features that we see in our tomographic image are very different from what has been seen before using traditional seismic inversion techniques," said Min Chen, the Rice research scientist who headed the project. "Because we used full waveform inversion to assimilate a large seismic data set, we were able to see more clearly how the upper-mantle lithosphere beneath Southern Tibet differs from that of the surrounding region. Our seismic image suggests that the Tibetan lithosphere thickened and formed a denser root that broke away and sank deeper into the mantle. We conclude that most of the uplift across Southern Tibet likely occurred when this lithospheric root broke away."
The research could help answer longstanding questions about Tibet's formation. Known as the "Roof of the World," the Tibetan Plateau stands more than three miles above sea level. The basic story behind its creation -- the tectonic collision between the Indian and Eurasian continents -- is well-known to schoolchildren the world over, but the specific details have remained elusive. For example, what causes the plateau to rise and how does its high elevation impact Earth's climate?
"The leading theory holds that the plateau rose continuously once the India-Eurasia continental collision began, and that the plateau is maintained by the northward motion of the Indian plate, which forces the plateau to shorten horizontally and move upward simultaneously," said study co-author Fenglin Niu, a professor of Earth science at Rice. "Our findings support a different scenario, a more rapid and pulsed uplift of Southern Tibet."
It took three years for Chen and colleagues to complete their tomographic model of the crust and upper-mantle structure beneath Tibet. The model is based on readings from thousands of seismic stations in China, Japan and other countries in East Asia. Seismometers record the arrival time and amplitude of seismic waves, pulses of energy that are released by earthquakes and that travel through Earth. The arrival time of a seismic wave at a particular seismometer depends upon what type of rock it has passed through. Working backward from instrument readings to calculate the factors that produced them is something scientists refer to as an inverse problem, and seismological inverse problems with full waveforms incorporating all kinds of usable seismic waves are some of the most complex inverse problems to solve.
Chen and colleagues used a technique called full waveform inversion, "an iterative full waveform-matching technique that uses a complicated numerical code that requires parallel computing on supercomputers," she said.
"The technique really allows us to use all the wiggles on a large number of seismographs to build up a more realistic 3-D model of Earth's interior, in much the same way that whales or bats use echo-location," she said. "The seismic stations are like the ears of the animal, but the echo that they are hearing is a seismic wave that has either been transmitted through or bounced off of subsurface features inside Earth."
The tomographic model includes features to a depth of about 500 miles below Tibet and the Himalaya Mountains. The model was computed on Rice's DAVinCI computing cluster and on supercomputers at the University of Texas that are part of the National Science Foundation's Extreme Science and Engineering Discovery Environment (XSEDE).
"The mechanism that led to the rise of Southern Tibet is called lithospheric thickening and foundering," Chen said. "This happened because of convergence of two continental plates, which are each buoyant and not easy to subduct underneath the other plate. One of the plates, in this case on the Tibetan side, was more deformable than the other, and it began to deform around 45 million years ago when the collision began. The crust and the rigid lid of upper mantle -- the lithosphere -- deformed and thickened, and the denser lower part of this thickened lithosphere eventually foundered, or broke off from the rest of the lithosphere. Today, in our model, we can see a T-shaped section of this foundered lithosphere that extends from a depth of about 250 kilometers to at least 660 kilometers."
Chen said that after the denser lithospheric root broke away, the remaining lithosphere under Southern Tibet experienced rapid uplift in response.
"The T-shaped piece of foundered lithosphere sank deeper into the mantle and also induced hot upwelling of the asthenosphere, which leads to surface magmatism in Southern Tibet," she said.
Such magmatism is documented in the rock record of the region, beginning around 30 million years ago in an epoch known as the Oligocene.
"The spatial correlation between our tomographic model and Oligocene magmatism suggests that the Southern Tibetan uplift happened in a relatively short geological span that could have been as short as 5 million years," Chen said.
Additional co-authors include Adrian Lenardic, Cin-Ty Lee, Wenrong Cao and Julia Ribeiro, all of Rice, and Jeroen Tromp of Princeton University.
The research was supported by a grant from the National Science Foundation (NSF), by the NSF's Extreme Science and Engineering Discovery Environment (XSEDE) program, and by the China Earthquake Administration's China Seismic Array Data Management Center. Rice's DAVinCI supercomputer is administered by Rice's Center for Research Computing and procured in partnership with the Ken Kennedy Institute for Information Technology.
The DOI of the Nature Communications paper is: 10.1038/NCOMMS15659
A copy of the paper, "Lithospheric Foundering and Underthrusting Imaged Beneath Tibet," is available at: https:/
More information is available at:
Rice Earth Science: https:/
Rice Research Computing: https:/
Min Chen home page: https:/
This release can be found online at news.rice.edu.
Follow Rice News and Media Relations on Twitter @RiceUNews.
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,879 undergraduates and 2,861 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl.
David Ruth | EurekAlert!
New research calculates capacity of North American forests to sequester carbon
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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An international team of botanists from Brazil, USA and the Botanische Staatssammlung München, Germany described a new species of carnivorous sundew (Drosera, Droseraceae), which was discovered on a not-so-remote mountain in Southeastern Brazil. The new species, which has been named Drosera magnifica (the magnificent sundew), turned out to be the largest of its kind known from the Americas, attaining a total length of 1.5m.
The spectacular thread-like carnivorous foliage is up to 24 cm long forming medusa-like clusters of sticky, glistening leaves.
Although discoveries of new species are not unusual, even nowadays, the way in which this new giant sundew species was discovered is exceptional: it is the first time that a new plant species has been discovered from a photograph which was posted on the social network Facebook.
A local orchid and native flora enthusiast posted the pictures in 2013, taken while exploring mountains near his hometown in Minas Gerais state. The pictures were picked up and immediately identified as a new sundew species by carnivorous plant experts Fernando Rivadavia and Paulo Gonella.
The new species has now been published in the renowned taxonomical journal Phytotaxa, including a detailed scientific description of the plant and a brief history of its unusual discovery.
“The genus Drosera, also known as sundews, is the largest group of carnivorous plants, and comprises approximately 250 species, most of them found in the Southern Hemisphere, especially in Australia, South Africa and Brazil”, says Dr. Andreas Fleischmann from the SNSB, Botanische Staatssammlung München, senior author of the publication.
Sundews produce leaves that are covered with carnivorous glands, so-called tentacles, which produce sticky droplets of a viscous fluid. These glistening red tentacles constitute visually attractive yet deadly traps for small arthropods, especially small flying insects. Indeed, “even under the humid, foggy and rainy conditions on the mountain summit where it grows, the long thread-like leaves of Drosera magnifica surprisingly were covered with lots of small insects”, says sundew expert Fernando Rivadavia, who studied the plants in nature in 2013, soon after its discovery on Facebook.
In most Drosera species, the tentacles and even the leaves are capable of movement, and will bend over the caught prey, entangling it with more glue and adhering it to more glands. The insects then suffocate and are slowly digested by enzymes secreted by the plant. This ensures a nutrient boost from its carnivorous diet, supplementing the nutrient-poor soils on which most carnivorous plant species usually grow.
It is interesting that such a large and conspicuous plant species has remained undiscovered until now, even though it was not growing on a terribly remote Amazonian mountain. This is an example of how little is still known about Brazilian biodiversity, even in the more well-developed parts of the country.
Despite being quite distinctive and unusual, the new species also shares some similarities with two other sundew species which were discovered and named 200 years ago, and are found on other highlands over 200km away, also in Southeastern Brazil.
Sadly, the magnificent sundew is already threatened with extinction. The new species was only found on a single mountain top rising above small ranches, coffee farms, and eucalyptus plantations. Invasive plant species were observed almost all the way to the top of the mountain, which is almost completely deforested around the base and is currently not protected by any kind of nature preserve or national park. Nearby mountains were explored by the scientists, but no other populations of this sundew have been found yet.
“We hope that the discovery of such an extraordinary new plant species will bring attention to the conservation of this fragile ecosystem. It was a surprise to all of us that this region of Minas Gerais was so poorly botanized, potentially harboring several other undescribed new plant species”, states Paulo Gonella, from the Systematic Botany Labs of the University of São Paulo, Brazil, who is currently working on the systematics and phylogeny of New World sundews in Munich, Germany.
Gonella, P.M., Rivadavia, F., Fleischmann, A. (2015). Drosera magnifica (Droseraceae): the largest New World sundew, discovered on Facebook. Phytotaxa 220 (3): 257-267. http://dx.doi.org/10.11646/phytotaxa.220.3.4
Contact: Brazil: Paulo Gonella
USA: Fernando Rivadavia
Europe: Dr. Andreas Fleischmann, SNSB, Botanische Staatssammlung München
Dr. Eva-Maria Natzer | idw - Informationsdienst Wissenschaft
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
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17.07.2018 | Power and Electrical Engineering | <urn:uuid:dc1ffa58-6007-46bc-a2fb-c7d597ab6774> | 3.3125 | 1,704 | Knowledge Article | Science & Tech. | 38.953505 | 95,566,367 |
Experiments on Resistance
In the previous chapters we have witnessed the existence of an experimental world in intimate relation with the theoretical world. Experimentation, which is a questioning of nature, is not a neutral or aseptic activity, but one that in itself implies a theory of the experiment and a theory of its interpretation. The first includes apparatus, circumstances and observers; the second deals with the reading and evaluation of the results, which are not normally as clear or immediate as to allow radical conclusions, requiring instead analyses which are generally complex.
These extremes, briefly noted, are especially notable when it comes to the experiments of resistance carried out in the eighteenth century. The discrepancies between theories and measurements were considerable, and it is interesting to see how the experimenters tailored the measurements, interpretations or apparatus to the results they were seeking. However, in the long run, experimental measurements took precedence, and as a result impact theory was discarded in an almost traumatic manner. Nevertheless, it took many years to arrive at an understanding of the multiple aspects of the phenomena of resistance.
There were also other causes of the experimentation boom. The theory is not wholly removed from experimentation, since the equations respond to models that participate in both the conceptual abstractions and the observed facts, as abstraction and reality are profoundly interwoven. Therefore, observation, comparison and accurate and rigorous measurements of the phenomena are necessary steps in the development of hydrodynamics. However, the task was slow, arduous and costly and it was necessary to wait until the following century to reap the fruits of the new science. Hahn recalls the words of Alexander Koyré concerning the historical moment in which ‘experience’ was transformed into ‘experimentation’ and hydrodynamics became an ‘active science’.
KeywordsEighteenth Century Fluid Mechanic Resistance Coefficient Previous Chapter Open Canal
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Radiocarbon dating age
To give an example if a sample is found to have a radiocarbon concentration exactly half of that for material which was modern in 1950 the radiocarbon measurement would be reported as 5568 BP.
For two important reasons, this does not mean that the sample comes from 3619 BC: Many types of tree reliably lay down one tree ring every year.
Archaeologists have long used carbon-14 dating (also known as radiocarbon dating) to estimate the age of certain objects.
Traditional radiocarbon dating is applied to organic remains between 500 and 50,000 years old and exploits the fact that trace amounts of radioactive carbon are found in the natural environment.
Libby, a Professor of Chemistry at the University of Chicago, predicted that a radioactive isotope of carbon, known as carbon-14, would be found to occur in nature.
Radiocarbon measurements are always reported in terms of years `before present' (BP).
This figure is directly based on the proportion of radiocarbon found in the sample.
The new method is based on the fact that over the past 60 years, environmental levels of radiocarbon have been significantly perturbed by mid-20th-century episodes of above-ground nuclear weapons testing.
Before the nuclear age, the amount of radiocarbon in the environment varied little in the span of a century.The wood in these rings once laid down remains unchanged during the life of the tree. | <urn:uuid:2d4f9675-420b-4f24-ade0-da440762b0c6> | 3.640625 | 302 | Knowledge Article | Science & Tech. | 37.698797 | 95,566,384 |
Imagine a gigantic, inflatable, sausage-like bag capable of storing 160 million tonnes of CO2 – the equivalent of 2.2 days of current global emissions. Now try to picture that container, measuring up to 100 metres in radius and several kilometres long, resting benignly on the seabed more than 3 kilometres below the ocean’s surface.
Uh, no thanks, I'd rather not image that thankyouverymuch.
Lets see, km long bags for every 2.2 days of emissions means that in just 1 year we'll have 100 or so of these bags "floating" at the bottom of the ocean. For how long will they float there?
The use of containment is necessary because CO2 will tend to dissolve in the ocean, which could adversely impact marine ecosystems. Fortunately, says Keith, the cost of containment is quite minimal with this solution. He and his colleagues calculate that the bags can be constructed of existing polymers for less than four cents per tonne of carbon.
Oh. So FOREVER.
Hundreds of bags per year stored at the bottom of the ocean. If any of the bags break (and they only need a small leak), they have disastrous consequences for marine life.
Let me ask one important question. Whenever has man made a maintenance-free structure that can last forever?
That's right, we haven't yet.
I'll go back to day-dreaming about space travel and hot aliens wanting my body, rather than this proposed nightmare. | <urn:uuid:c3b49e84-ae37-49fb-9a36-7144e5d5a3c5> | 3.203125 | 310 | Personal Blog | Science & Tech. | 61.112783 | 95,566,388 |
27 Oct , 2017 by Matt Williams
Thanks to a new study by an international team of astronomers, we now have the tools we need to map the far side of our galaxy.
Astronomy, Guide to Space
25 Jul , 2016 by Tammy Plotner
Located in the southern Sagittarius constellation is the Trifid Nebula, a bright star-forming region and combination nebula
4 Jul , 2016 by Tammy Plotner
Located between 5,000 and 6,000 light years from Earth is the Omega Nebula, one of the brightest and most massive star-forming regions in our galaxy
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Understanding the differences and similarities will help improve how models represent storm clouds and other convective processes.
Precipitation is difficult to represent in global climate models. Although most single-column models can reproduce the observed average precipitation reasonably well, there are significant differences in their details, including mean precipitation intensity. Scientists evaluated the performance of seven single-column models, used by global models to complex processes, by comparing simulated surface precipitation with observations.
The different single-column models’ performances and associations with large-scale conditions provide insights on how to improve climate models’ representation of convection, the movement of heat or air through fluids. Convection is integral to forming storm clouds. The insights gained here will also improve approaches for future testing.
Precipitation is one of the most poorly parameterized physical processes in global climate models. Scientists often use a single grid-box column of a global climate model or a single-column model to more efficiently study and test the process representations or parameterization schemes in global climate models. The single-column model approach is also a key strategy of the U.S. Department of Energy’s (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility and Atmospheric System Research activity.
However, most single-column model intercomparison studies organized by ARM have been focused on special cases or week- to month-long periods. To make a statistically meaningful comparison and evaluation of modeled precipitation, researchers conducted 3-year-long single-column model simulations of seven global climate models participating in the Fast-physics System Testbed and Research (FASTER) project at the ARM Southern Great Plains site.
Results of the study, conducted by DOE scientists at Brookhaven National Laboratory, show that although most single column models can reproduce the observed average precipitation reasonably well, there are significant differences in their details.
These variations (both among models and between models and observations) include differences between daytime and nighttime, warm and cold seasons, frequency and mean precipitation intensity, and convective and stratiform partition. Further analysis reveals distinct meteorological backgrounds for large underestimation and overestimation precipitation events. The former occur in strong ascending regimes with negative low-level horizontal heat and moisture influx, while the latter occur in the weak or moderate ascending regimes with positive low-level horizontal heat and moisture influx.
This work is part of the FASTER project supported by the U.S. Department of Energy’s Earth System Modeling program.
H. Song, W. Lin, Y. Lin, A.B. Wolf, R. Neggers, L.J. Donner, A.D. Del Genio, Y. Liu, “Evaluation of precipitation simulated by seven SCMs against the ARM observations at the SGP site.” Journal of Climate 26 (15), 5467–5492 (2013). [DOI: 10.1175/JCLI-D-12-00263.1]
Kristin Manke | newswise
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
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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....
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One of the most important functions of living cells is to produce the proteins necessary for an organism’s survival. Proteins give shape and structure to an organism and, as enzymes, regulate biological activity. To manufacture proteins, a cell needs to read and interpret the genetic information stored in its deoxyribonucleic acid, or DNA. The sites of cellular protein synthesis are the ribosomes, which can be free or bound. The importance of the free ribosome is that protein synthesis begins there.
DNA and RNA
DNA is a long molecular chain composed of alternating sugar and phosphate groups. One of four possible nitrogen-containing nucleotide bases -- A, C, T and G -- hangs off each sugar. The sequence of the bases along the DNA strand determines the sequence of amino acids that form proteins. Ribonucleic acid, or RNA, transmits a complementary copy of a portion of a DNA molecule -- a gene -- to ribosomes, which are tiny granules composed of RNA and protein. RNA resembles DNA except that its sugar groups contain an extra oxygen atom and it substitutes the U nucleotide base for DNA’s T base. The ribosomes create proteins according to the information stored in the messenger RNA, or mRNA.
The rules for transcribing DNA to RNA specify a correspondence between bases on the gene and bases on the mRNA. For example, an A base in a gene specifies a U base in the mRNA strand. Similarly, a gene’s T, C and G bases specify A, G, and C bases, respectively, in mRNA. The genetic information contained in mRNA takes the form of triplets of nucleotide bases called codons. For example, the DNA triplet TAA creates the RNA triplet UTT. The DNA and RNA strands therefore contain complementary, yet unique, information encoded in the sequence of nucleotide bases. Almost every triplet codes for a specific amino acid, although a few triplets specify the end of a gene. Several different triplets can code for the same amino acid.
The cell manufactures ribosomes directly from ribosomal RNA, or rRNA, encoded by specific DNA genes. The rRNA combines with proteins to form large and small subunits. The two subunits only join during protein synthesis. In a prokaryotic cell -- that is, a cell without an organized nucleus -- the ribosome subunits float freely within the cell liquid, or cytosol. In eukaryotes, enzymes in a cell’s nucleus build ribosome subunits. The nucleus then exports the subunits to the cytosol. Some of the ribosomes may temporarily bind to a cell organelle called the endoplasmic reticulum, or ER, when building proteins, while other ribosomes remain free as they synthesize proteins.
A free ribosome’s smaller subunit grabs hold of an mRNA strand to begin protein synthesis. The larger subunit then hooks on and begins translating each mRNA codon. This entails exposing and positioning each mRNA codon so that enzymes can identify and attach the amino acid corresponding to the current codon. A molecule of transfer RNA, or tRNA, with a complementary anti-codon locks into the larger subunit, its designated amino acid in tow. Enzymes then transfer the amino acid to the growing protein chain, expel the spent tRNA for reuse, and expose the next mRNA codon. When finished, the ribosome releases the new protein and the two subunits dissociate. | <urn:uuid:edc448a9-841b-4ead-8429-aa5a23792513> | 4.40625 | 723 | Knowledge Article | Science & Tech. | 38.575221 | 95,566,438 |
A comprehensive new study authored by University at Buffalo scientists and their colleagues for the first time documents in detail the dynamics of parts of Greenland's ice sheet, important data that have long been missing from the ice sheet models on which projections about sea level rise and global warming are based.
The research, published online this month in the Journal of Glaciology, also demonstrates how remote sensing and digital imaging techniques can produce rich datasets without field data in some cases.
Traditionally, ice sheet models are very simplified, according to Beata Csatho, Ph.D., assistant professor of geology in the UB College of Arts and Sciences and lead author of the paper.
"Ice sheet models usually don't include all the complexity of ice dynamics that can happen in nature," said Csatho. "This research will give ice sheet modelers more precise, more detailed data."
The implications of these richer datasets may be dramatic, Csatho said, especially as they impact climate projections and sea-level rise estimates, such as those made by the United Nations Intergovernmental Panel on Climate Change (IPCC).
"If current climate models from the IPCC included data from ice dynamics in Greenland, the sea level rise estimated during this century could be twice as high as what they are currently projecting," she said.
The paper focuses on Jakobshavn Isbrae, Greenland's fastest moving glacier and its largest, measuring four miles wide.
During the past decade, Jakobshavn Isbrae has begun to experience rapid thinning and doubling of the amount of ice it discharges into Disko Bay.
"Although the thinning started as early as the end of the 18th century, the changes we are seeing now are bigger than can be accounted for by normal, annual perturbations in climate," Csatho said.
In order to document the most comprehensive story possible of the behavior of Jakobshavn Isbrae since the Little Ice Age in the late 1800s, Csatho and her colleagues at Ohio State University, the University of Kansas and NASA used a combination of techniques.
These included field mapping, remote sensing, satellite imaging and the application of digital techniques in order to glean "hidden" data from historic aerial photographs as many as 60 years after they were taken.
By themselves, Csatho explained, the two-dimensional pictures were of limited value.
"But now we can digitize them, removing the boundaries between them and turning several pictures into a single 'mosaic' that will produce one data set that can be viewed in three-dimensions," she said.
"By reprocessing old data contained in these old photographs and records, we have been able to construct a long-term record of the behavior of the glacier," said Csatho. "This was the first time that the data from the '40s could be reused in a coherent way."
The data from the historic photos were combined with data from historical records, ground surveys, field mapping and measurements taken from the air to document important signs of change in the glacier's geometry.
Csatho explained that conventional methods of assessing change in glaciers have depended on documenting "iceberg calving," in which large pieces at the front of the glacier break off.
"But we found that you can get significant changes in the ice sheet without seeing a change in front," she said.
Other key findings of the paper are that two different parts of the same glacier may behave quite differently and that a glacier does not necessarily react to climate change as a single, monolithic entity.
"Climate forces are complex," Csatho said. "For example, we found that the northern part of Jakobshavn was still thinning while the climate was colder between the 1960s and the 1990s."
Csatho, who is a geophysicist, added that the research is the result of a strong interdisciplinary team involving experts in glaciology, ice sheet modeling and photogrammetry, the science of making measurements based on photographs.
At UB, research in Csatho's remote sensing laboratory -- http://rsl.geology.buffalo.edu/ -- focuses on a multidisciplinary approach that integrates information across the geosciences.
Csatho's co-authors on the paper are Tony Schenk of the Ohio State University Department of Civil and Environmental Engineering and Geodetic Science; Kees van der Veen of the Center for Remote Sensing of Ice Sheets at the University of Kansas, and William B. Krabill of the National Aeronautics and Space Administration's Cryospheric Sciences Branch.
The research was funded by the National Science Foundation and NASA.
The University at Buffalo is a premier research-intensive public university, a flagship institution in the State University of New York system that is its largest and most comprehensive campus. UB's more than 28,000 students pursue their academic interests through more than 300 undergraduate, graduate and professional degree programs. Founded in 1846, the University at Buffalo is a member of the Association of American Universities.
Ellen Goldbaum | EurekAlert!
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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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Community Contributor | Jul 3, 2018 | 0
Understanding weather – not predicting 6 september 2013
Winter 2013 departed, Spring is here.
Arid climates like Namibia are known by their “Variability”; a description unique in the climate world. Coupled with our unique geography, this variability leads to a divergent range of weather characteristics when measured from south to north, or from the coastal plains to the high interior plateau.
“Variability” in both rainfall and temperature is the norm in local weather. Our experience is that while we have an identifiable rainfall season during summer and autumn, its trademark is still a high degree of variability across both time and place.
For instance, the Karas Region receives some winter rainfall as the winter rainfall systems that regularly cross the Cape of Good Hope push northward, but these falls are erratic and mostly patchy. Overall, this winter has fallen short where rain is concerned across our south. Elsewhere these three months contribute less than a mere percent of the overall; Spring doesn’t do much better, apart from November the input is some 3%. Effective rain further north than the Karas Region, is as good as absent in these 5 months.
Temperature: – cooled by the considerable elevation limiting most of the country to below 40oC maxima, the winter also can provide astonishing ranges on just a single day. This week gave such an example. While southerly daytime maxima struggled to reach the mid-teens, across our northern areas night-time minima were, on the same day, a degree or two above that level. This is also typical of the Namibian Spring and there is a touch of the global warming influence here.
Rain petered out by Sunday: Rosh Pinah Exxaro: 8 and 2mm: the 3 consecutive days of 1mm or more matches their previous best. Karasburg 2 and 0.1. Reports from as far north as Grünau told of 13mm. Witputs district had some 41mm, the result of orographic influence exemplified!
Successive troughs crossed the western Cape barely reaching our far south. Increasing daytime solar heat gave midday warmth for much of the interior.
The anticyclonic control saw a middle layer, 700 to 500hPa levels, flow tapping air from some 10oS. by Wednesday and thickened by Thursday with a thin Altocumulus layer as its trademark.
Currently, outlooks offer the same synoptics close to, but not entering, our air space. Progressive anticyclones push low level ridges eastward reinforcing the persistent Mascarene anticyclone: another situation most desirable those few months ahead!
The easterly surface flow persists, one way or another, for most of the interior. To our west is a perceived lack of coordination between surface level patterns and those of lower level upper air charts, 700hPa and above. Anticyclonic control to our south at surface level fades by 850hPa while an upper trough emerges by mid-week: persistent northwesterly flow invites this but this new upper flow is dry, with no absorption of maritime moisture. A shallow cloud layer is its best offering. | <urn:uuid:09a0e84a-4c0c-4168-8c99-04dbbe812254> | 2.703125 | 665 | News Article | Science & Tech. | 43.619957 | 95,566,451 |
Our regular Science and the SeaTM radio program presents marine science topics in an engaging two-minute story format. Our script writers gather ideas for the radio program from the University of Texas Marine Science Institute's researchers and from our very popular college class, Introduction to Oceanography, which we teach to hundreds of non-science majors at The University of Texas at Austin every year. Our radio programs are distributed at to commercial and public radio stations across the country.
The male Gulf corvina is a loudmouth. In fact, it may be too loud for its own good. Its sounds guide fishing boats right to its own spawning grounds. And that could endanger the entire corvina population.
Appropriately enough, Gulf corvina are a type of croaker. They inhabit the Gulf of California, between Baja California and the Mexican mainland. Every spring, the entire adult population gathers to spawn at the northern edge of the gulf -- at the mouth of the Colorado River. To help them attract mates, male corvina make a lot of noise -- a series of short, loud pulses.
A hundred million years ago, Kansas was inhabited by some creatures with big, sharp teeth: sharks up to 30 feet long, a fish that’s been described as a tarpon with fangs, and a 45-foot dinosaur that was one of the deadliest predators on the planet.
That’s because Kansas was at the bottom of a sea that stretched from the Arctic to the Gulf of Mexico. Known as the Western Interior Sea, it was up to a thousand miles wide. Its warm, shallow waters supported an abundance of life, including giant clams, giant fish, and giant dinosaurs.
The polar bear is more than just a big mammal; it’s an icon for an entire region -- it’s hard to think of the Arctic without picturing these beautiful creatures. Yet it’s also a symbol for how that region is changing. A warmer climate is reducing the amount of sea ice in the Arctic, which could lead to a big reduction in polar bear populations.
No bear is bigger than the polar bear -- an adult male can weigh up to three-quarters of a ton. To maintain that size, polar bears spend much of their time hunting seals, which are rich in fat and calories.
When you bite into an ear of corn, you’re after the juicy kernels. But if you get a little too enthusiastic, you can get some of the cob, too.
One type of fish always bites into the cob. The parrotfish eats the living parts of coral, as well as algae on the coral. To get the good stuff, though, it has to bite into the coral skeleton -- a structure that’s like rock. That’s tough on the teeth. But a recent study says those teeth are well designed for the job. They’re hard, stiff, and they seldom break.
If zombies ever run out of brains to munch on, they might look to the sea for more. They can find brains that are up to six feet tall and live for almost a millennium. The brains might be a little crunchy, though -- they’re corals, so they consist of a hard skeleton with a thin coating of living organisms.
Brain corals are generally round or oblong, with a wrinkled surface that looks like the contours of a human brain. They’re found in tropical waters in the Caribbean, the Gulf of Mexico, parts of the Atlantic, and elsewhere.
The big ships that ply the Indian Ocean and South China Sea help power the world’s economy. And they also may help power the weather. In particular, they may “seed” the formation of tall clouds that produce lightning -- twice as much lightning along their shipping lanes as in the surrounding ocean.
Researchers were mapping lightning strikes in that part of the world when they noticed something odd: two straight lines where there were far more lightning strikes than average. They compared those maps with traffic along the shipping lanes, and found that the two matched perfectly.
We humans have been known to eat some pungent foods, from boiled cabbage to brussels sprouts to limburger-and-onion sandwiches. But a mollusk that lives in the mud at the bottom of a Philippine lagoon tops them all. It gets by on hydrogen sulfide -- a nasty gas that smells like rotten eggs. Or to be more precise, bacteria that live in its gills consume the hydrogen sulfide and convert it to a more palatable form.
Many marine creatures hang out in beds of seagrass or kelp to hide from predators or prey. But the leafy seadragon beats them all. It’s covered with leafy appendages that make it look like a bit of kelp. And it floats along with the currents just like the kelp, so it’s hard for either prey or predator to pick it out.
The heart of a typical adult human can pump about 2,000 gallons of blood per day. But that’s anemic compared to the pumping capacity of a sponge -- the living kind, not the kind you use to wash off your kitchen cabinets. The amount of water it pumps can be up to 20,000 times the volume of its own body. For a good-sized sponge, that can be almost 20,000 gallons a day.
James Bond, Indiana Jones, and other action heroes can’t seem to avoid waterfalls. They plummet down them, or they just miss them, narrowly avoiding a gruesome fate.
But no hero has taken the plunge down the world’s tallest waterfall -- and probably won’t anytime soon. That’s because it’s under water -- a two-mile drop between Greenland and Iceland. | <urn:uuid:371b5702-9e84-4a2d-aaef-23780a1cdd35> | 3.46875 | 1,204 | Content Listing | Science & Tech. | 62.532009 | 95,566,459 |
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Edited By: Sylvie Gourlet-Fleury, Jean-Marc Guehl and Olivier Laroussinie
310 pages, illus
In 1982, the "Silvicultural research on the natural forest stands of French Guiana" operation was initiated, and since then, the Paracou experimental site has been a favourite place for basic ecological research concerning the structure, dynamics, diversity and functioning of the lowland rainforest of coastal French Guiana. the site offers more than 100 hectares of plots where trees are fully mapped, and an experimental design combining logging and thinning with undisturbed controls, allowing assessment of the impact of well-documented disturbances on the characteristics of various forest stands and tree populations.
In this book, 40 authors summarise their experience and results at Paracou. Topics include (i) forest structure and floristic composition; (ii) ecosystem-level carbon dynamics; (iii) light requirements, patterns of water use and root symbiotic status of the main species, (iv) gene flow and genetic diversity; (v) regeneration strategies, growth behaviour and dynamics of stands before and after sylvicultural operations; (vi) modelling of forest dynamics. A final chapter discusses the practical lessons for forest management that have resulted from research operations at Paracou.
This book is intended for advanced students and researchers in tropical forestry and ecology, as well as forest managers and decision-makers concerned by the potential impact of human actions on tropical forest ecosystems.
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The glass–liquid transition, or glass transition, is the gradual and reversible transition in amorphous materials (or in amorphous regions within semicrystalline materials), from a hard and relatively brittle "glassy" state into a viscous or rubbery state as the temperature is increased. An amorphous solid that exhibits a glass transition is called a glass. The reverse transition, achieved by supercooling a viscous liquid into the glass state, is called vitrification.
The glass-transition temperature Tg of a material characterizes the range of temperatures over which this glass transition occurs. It is always lower than the melting temperature, Tm, of the crystalline state of the material, if one exists.
Hard plastics like polystyrene and poly(methyl methacrylate) are used well below their glass transition temperatures, that is in their glassy state. Their Tg values are well above room temperature, both at around 100 °C (212 °F). Rubber elastomers like polyisoprene and polyisobutylene are used above their Tg, that is, in the rubbery state, where they are soft and flexible.
Despite the change in the physical properties of a material through its glass transition, the transition is not considered a phase transition; rather it is a phenomenon extending over a range of temperature and defined by one of several conventions. Such conventions include a constant cooling rate (20 kelvins per minute (36 °F/min)) and a viscosity threshold of 1012 Pa·s, among others. Upon cooling or heating through this glass-transition range, the material also exhibits a smooth step in the thermal-expansion coefficient and in the specific heat, with the location of these effects again being dependent on the history of the material. The question of whether some phase transition underlies the glass transition is a matter of continuing research.
The glass transition of a liquid to a solid-like state may occur with either cooling or compression. The transition comprises a smooth increase in the viscosity of a material by as much as 17 orders of magnitude within a temperature range of 500 K without any pronounced change in material structure. The consequence of this dramatic increase is a glass exhibiting solid-like mechanical properties on the timescale of practical observation. This transition is in contrast to the freezing or crystallization transition, which is a first-order phase transition in the Ehrenfest classification and involves discontinuities in thermodynamic and dynamic properties such as volume, energy, and viscosity. In many materials that normally undergo a freezing transition, rapid cooling will avoid this phase transition and instead result in a glass transition at some lower temperature. Other materials, such as many polymers, lack a well defined crystalline state and easily form glasses, even upon very slow cooling or compression. The tendency for a material to form a glass while quenched is called glass forming ability. This ability depends on the composition of the material and can be predicted by the rigidity theory.
Below the transition temperature range, the glassy structure does not relax in accordance with the cooling rate used. The expansion coefficient for the glassy state is roughly equivalent to that of the crystalline solid. If slower cooling rates are used, the increased time for structural relaxation (or intermolecular rearrangement) to occur may result in a higher density glass product. Similarly, by annealing (and thus allowing for slow structural relaxation) the glass structure in time approaches an equilibrium density corresponding to the supercooled liquid at this same temperature. Tg is located at the intersection between the cooling curve (volume versus temperature) for the glassy state and the supercooled liquid.
The configuration of the glass in this temperature range changes slowly with time towards the equilibrium structure. The principle of the minimization of the Gibbs free energy provides the thermodynamic driving force necessary for the eventual change. It should be noted here that at somewhat higher temperatures than Tg, the structure corresponding to equilibrium at any temperature is achieved quite rapidly. In contrast, at considerably lower temperatures, the configuration of the glass remains sensibly stable over increasingly extended periods of time.
Thus, the liquid-glass transition is not a transition between states of thermodynamic equilibrium. It is widely believed that the true equilibrium state is always crystalline. Glass is believed to exist in a kinetically locked state, and its entropy, density, and so on, depend on the thermal history. Therefore, the glass transition is primarily a dynamic phenomenon. Time and temperature are interchangeable quantities (to some extent) when dealing with glasses, a fact often expressed in the time–temperature superposition principle. On cooling a liquid, internal degrees of freedom successively fall out of equilibrium. However, there is a longstanding debate whether there is an underlying second-order phase transition in the hypothetical limit of infinitely long relaxation times.[clarification needed]
Transition temperature Tg
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Refer to the figure on the right plotting the heat capacity as a function of temperature. In this context, Tg is the temperature corresponding to point A on the curve. The linear sections below and above Tg are colored green. Tg is the temperature at the intersection of the red regression lines.
Different operational definitions of the glass transition temperature Tg are in use, and several of them are endorsed as accepted scientific standards. Nevertheless, all definitions are arbitrary, and all yield different numeric results: at best, values of Tg for a given substance agree within a few kelvins. One definition refers to the viscosity, fixing Tg at a value of 1013 poise (or 1012 Pa·s). As evidenced experimentally, this value is close to the annealing point of many glasses.
In contrast to viscosity, the thermal expansion, heat capacity, shear modulus, and many other properties of inorganic glasses show a relatively sudden change at the glass transition temperature. Any such step or kink can be used to define Tg. To make this definition reproducible, the cooling or heating rate must be specified.
The most frequently used definition of Tg uses the energy release on heating in differential scanning calorimetry (DSC, see figure). Typically, the sample is first cooled with 10 K/min and then heated with that same speed.
Yet another definition of Tg uses the kink in dilatometry (a.k.a. thermal expansion). Here, heating rates of 3–5 K/min (5.4–9.0 °F/min) are common. Summarized below are Tg values characteristic of certain classes of materials.
|Material||Tg (°C)||Tg (°F)||Commercial name|
|Polyvinylidene fluoride (PVDF)||−35||−31|
|Polypropylene (PP atactic)||−20||−4|
|Polyvinyl fluoride (PVF)||−20||−4|
|Polypropylene (PP isotactic)||0||32|
|Poly(vinyl acetate) (PVAc)||30||86|
|Polylactic acid (PLA)||60–65||140–149|
|Polyethylene terephthalate (PET)||70||158|
|Poly(vinyl chloride) (PVC)||80||176|
|Poly(vinyl alcohol) (PVA)||85||185|
|Poly(methyl methacrylate) (PMMA atactic)||105||221||Plexiglas, Perspex|
|Acrylonitrile butadiene styrene (ABS)||105||221|
Dry nylon-6 has a glass transition temperature of 47 °C (117 °F). Nylon-6,6 in the dry state has a glass transition temperature of about 70 °C (158 °F). Whereas polyethene has a glass transition range of −130 – −80 °C (−202 – −112 °F) The above are only mean values, as the glass transition temperature depends on the cooling rate and molecular weight distribution and could be influenced by additives. For a semi-crystalline material, such as polyethene that is 60–80% crystalline at room temperature, the quoted glass transition refers to what happens to the amorphous part of the material upon cooling.
Silicates and other covalent network glasses
|Material||Tg (°C)||Tg (°F)|
|ZBLAN fluoride glass||235||455|
|Fused quartz (approximate)||1,200||2,200|
As a liquid is supercooled, the difference in entropy between the liquid and solid phase decreases. By extrapolating the heat capacity of the supercooled liquid below its glass transition temperature, it is possible to calculate the temperature at which the difference in entropies becomes zero. This temperature has been named the Kauzmann temperature.
If a liquid could be supercooled below its Kauzmann temperature, and it did indeed display a lower entropy than the crystal phase, the consequences would be paradoxical. This Kauzmann paradox has been the subject of much debate and many publications since it was first put forward by Walter Kauzmann in 1948.
One resolution of the Kauzmann paradox is to say that there must be a phase transition before the entropy of the liquid decreases. In this scenario, the transition temperature is known as the calorimetric ideal glass transition temperature T0c. In this view, the glass transition is not merely a kinetic effect, i.e. merely the result of fast cooling of a melt, but there is an underlying thermodynamic basis for glass formation. The glass transition temperature:
There are at least three other possible resolutions to the Kauzmann paradox. It could be that the heat capacity of the supercooled liquid near the Kauzmann temperature smoothly decreases to a smaller value. It could also be that a first order phase transition to another liquid state occurs before the Kauzmann temperature with the heat capacity of this new state being less than that obtained by extrapolation from higher temperature. Finally, Kauzmann himself resolved the entropy paradox by postulating that all supercooled liquids must crystallize before the Kauzmann temperature is reached.
In specific materials
Silica (the chemical compound SiO2) has a number of distinct crystalline forms in addition to the quartz structure. Nearly all of the crystalline forms involve tetrahedral SiO4 units linked together by shared vertices in different arrangements. Si-O bond lengths vary between the different crystal forms. For example, in α-quartz the bond length is 161 picometres (6.3×10−9 in), whereas in α-tridymite it ranges from 154–171 pm (6.1×10−9–6.7×10−9 in). The Si-O-Si bond angle also varies from 140° in α-tridymite to 144° in α-quartz to 180° in β-tridymite. Any deviations from these standard parameters constitute microstructural differences or variations that represent an approach to an amorphous, vitreous or glassy solid. The transition temperature Tg in silicates is related to the energy required to break and re-form covalent bonds in an amorphous (or random network) lattice of covalent bonds. The Tg is clearly influenced by the chemistry of the glass. For example, addition of elements such as B, Na, K or Ca to a silica glass, which have a valency less than 4, helps in breaking up the network structure, thus reducing the Tg. Alternatively, P, which has a valency of 5, helps to reinforce an ordered lattice, and thus increases the Tg.
Tg is directly proportional to bond strength, e.g. it depends on quasi-equilibrium thermodynamic parameters of the bonds e.g. on the enthalpy Hd and entropy Sd of configurons – broken bonds: Tg = Hd / [Sd + Rln[(1-fc)/ fc] where R is the gas constant and fc is the percolation threshold. For strong melts such as SiO2 the percolation threshold in the above equation is the universal Scher-Zallen critical density in the 3-D space e.g. fc = 0.15, however for fragile materials the percolation thresholds are material-dependent and fc << 1. The enthalpy Hd and the entropy Sd of configurons – broken bonds can be found from available experimental data on viscosity.
In polymers the glass transition temperature, Tg, is often expressed as the temperature at which the Gibbs free energy is such that the activation energy for the cooperative movement of 50 or so elements of the polymer is exceeded. This allows molecular chains to slide past each other when a force is applied. From this definition, we can see that the introduction of relatively stiff chemical groups (such as benzene rings) will interfere with the flowing process and hence increase Tg. The stiffness of thermoplastics decreases due to this effect (see figure.) When the glass temperature has been reached, the stiffness stays the same for a while, i.e., at or near E2, until the temperature exceeds Tm, and the material melts. This region is called the rubber plateau.
In ironing, a fabric is heated through this transition so that the polymer chains become mobile. The weight of the iron then imposes a preferred orientation. Tg can be significantly decreased by addition of plasticizers into the polymer matrix. Smaller molecules of plasticizer embed themselves between the polymer chains, increasing the spacing and free volume, and allowing them to move past one another even at lower temperatures. The addition of nonreactive side groups to a polymer can also make the chains stand off from one another, reducing Tg. If a plastic with some desirable properties has a Tg that is too high, it can sometimes be combined with another in a copolymer or composite material with a Tg below the temperature of intended use. Note that some plastics are used at high temperatures, e.g., in automobile engines, and others at low temperatures.
In viscoelastic materials, the presence of liquid-like behavior depends on the properties of and so varies with rate of applied load, i.e., how quickly a force is applied. The silicone toy Silly Putty behaves quite differently depending on the time rate of applying a force: pull slowly and it flows, acting as a heavily viscous liquid; hit it with a hammer and it shatters, acting as a glass.
On cooling, rubber undergoes a liquid-glass transition, which has also been called a rubber-glass transition.
Mechanics of vitrification
Molecular motion in condensed matter can be represented by a Fourier series whose physical interpretation consists of a superposition of longitudinal and transverse waves of atomic displacement with varying directions and wavelengths. In monatomic systems, these waves are called density fluctuations. (In polyatomic systems, they may also include compositional fluctuations.)
Thus, thermal motion in liquids can be decomposed into elementary longitudinal vibrations (or acoustic phonons) while transverse vibrations (or shear waves) were originally described only in elastic solids exhibiting the highly ordered crystalline state of matter. In other words, simple liquids cannot support an applied force in the form of a shearing stress, and will yield mechanically via macroscopic plastic deformation (or viscous flow). Furthermore, the fact that a solid deforms locally while retaining its rigidity – while a liquid yields to macroscopic viscous flow in response to the application of an applied shearing force – is accepted by many as the mechanical distinction between the two.
The inadequacies of this conclusion, however, were pointed out by Frenkel in his revision of the kinetic theory of solids and the theory of elasticity in liquids. This revision follows directly from the continuous characteristic of the structural transition from the liquid state into the solid one when this transition is not accompanied by crystallization—ergo the supercooled viscous liquid. Thus we see the intimate correlation between transverse acoustic phonons (or shear waves) and the onset of rigidity upon vitrification, as described by Bartenev in his mechanical description of the vitrification process.
The velocities of longitudinal acoustic phonons in condensed matter are directly responsible for the thermal conductivity that levels out temperature differentials between compressed and expanded volume elements. Kittel proposed that the behavior of glasses is interpreted in terms of an approximately constant "mean free path" for lattice phonons, and that the value of the mean free path is of the order of magnitude of the scale of disorder in the molecular structure of a liquid or solid. The thermal phonon mean free paths or relaxation lengths of a number of glass formers have been plotted versus the glass transition temperature, indicating a linear relationship between the two. This has suggested a new criterion for glass formation based on the value of the phonon mean free path.
It has often been suggested that heat transport in dielectric solids occurs through elastic vibrations of the lattice, and that this transport is limited by elastic scattering of acoustic phonons by lattice defects (e.g. randomly spaced vacancies). These predictions were confirmed by experiments on commercial glasses and glass ceramics, where mean free paths were apparently limited by "internal boundary scattering" to length scales of 10–100 micrometres (0.00039–0.00394 in). The relationship between these transverse waves and the mechanism of vitrification has been described by several authors who proposed that the onset of correlations between such phonons results in an orientational ordering or "freezing" of local shear stresses in glass-forming liquids, thus yielding the glass transition.
The influence of thermal phonons and their interaction with electronic structure is a topic that was appropriately introduced in a discussion of the resistance of liquid metals. Lindemann's theory of melting is referenced, and it is suggested that the drop in conductivity in going from the crystalline to the liquid state is due to the increased scattering of conduction electrons as a result of the increased amplitude of atomic vibration. Such theories of localization have been applied to transport in metallic glasses, where the mean free path of the electrons is very small (on the order of the interatomic spacing).
The formation of a non-crystalline form of a gold-silicon alloy by the method of splat quenching from the melt led to further considerations of the influence of electronic structure on glass forming ability, based on the properties of the metallic bond.
Other work indicates that the mobility of localized electrons is enhanced by the presence of dynamic phonon modes. One claim against such a model is that if chemical bonds are important, the nearly free electron models should not be applicable. However, if the model includes the buildup of a charge distribution between all pairs of atoms just like a chemical bond (e.g., silicon, when a band is just filled with electrons) then it should apply to solids.
Thus, if the electrical conductivity is low, the mean free path of the electrons is very short. The electrons will only be sensitive to the short-range order in the glass since they do not get a chance to scatter from atoms spaced at large distances. Since the short-range order is similar in glasses and crystals, the electronic energies should be similar in these two states. For alloys with lower resistivity and longer electronic mean free paths, the electrons could begin to sense that there is disorder in the glass, and this would raise their energies and destabilize the glass with respect to crystallization. Thus, the glass formation tendencies of certain alloys may therefore be due in part to the fact that the electron mean free paths are very short, so that only the short-range order is ever important for the energy of the electrons.
It has also been argued that glass formation in metallic systems is related to the "softness" of the interaction potential between unlike atoms. Some authors, emphasizing the strong similarities between the local structure of the glass and the corresponding crystal, suggest that chemical bonding helps to stabilize the amorphous structure.
Other authors have suggested that the electronic structure yields its influence on glass formation through the directional properties of bonds. Non-crystallinity is thus favored in elements with a large number of polymorphic forms and a high degree of bonding anisotropy. Crystallization becomes more unlikely as bonding anisotropy is increased from isotropic metallic to anisotropic metallic to covalent bonding, thus suggesting a relationship between the group number in the periodic table and the glass forming ability in elemental solids.
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So you want to get up to speed with Python. Here's a lightening tour for the beginning to intermediate programmer who is already familiar with some fundamental programming ideas.
Everthing is an Object
Is now available as a print book: Amazon
- Hello Python World
- Variables, Objects and Attributes
- The Function Object
- Scope, Lifetime and Closure
- Advanced Functions
Extract - Decorators
- Class Methods and Constructors
- Inside Class
- Metaclass ***NEW
- Advanced Attributes
- Custom Attribute Access
- Single Inheritance
- Multiple Inheritance
- Class and Type
- More Magic - Operator Overloading
First the usual basics - skip if you already know about Python's birth and background:
And now for something completely different – Python
Well, if you are going to venture into Python you might as well get used to the Monty Python quotes, and expect references to spam (a type of meatloaf and an acquired taste), Brian and grail (references to two classic films).
Although it is true to say that Monty Python references seem to be getting thinner on the ground than they used to be. Perhaps it isn't as well known any more.Instead you tend to see illustrations and allusions to snakes, obviously pythons in particular. Originally there was nothing snaky about the language.
I will try to redress the balance slightly in this introduction.
This is a brief introduction to Python for the beginning to intermediate programmer. It is assumed that you know enough about programming not to be confused by ideas such as variables, constants, loops and conditionals. It isn't a complete overview of Python more a guide to the things that an experienced programmer would notice or need to notice, in a first encounter.
Python is a free to use open source language. Developed by Guido van Rossum, an enthusiastic Monty Python fan, in 1990:
He is still very active on the project and is known affectionately in the Python community as Benevolent Dictator For Life or BDFL for short. Many of the characteristics of Python and the overall direction of the project are down to decisions made by Rossum.
Although it is copyrighted by van Rossum, you can use it and distribute it without charge, even for commercial use. You can download a Windows/Linux/Mac version complete with a visual development environment for free and the good news is that your Python application will often run irrespective of which platform you developed it on i.e. Python is largely platform independent.
The first question to answer is why bother?
Python may be a high quality language but so is Java!
Python is a phenomena of modern programming. It is an interpreted object oriented language that started out being simple and easy to use and has slowly collected a wide range of sophisticated features. The Python community is large and one of the most active. Python's excellent number crunching facilities have made it a number one choice for science and technology. In fact in many cases data scientists prefer its general purpose approach to more directly data oriented languages like R.
Having said all of this it also has to be said that Python has a slightly rough past which does hang around in the present. It wasn't particularly object oriented in its early days and today you can still write Python as if it was a scripting language. It is also dynamically typed. This is something that pleases many open minded programmers and infuriates the more strongly typed - you can guess which side of the argument I'm on.
In short Python is easy to get started with but it has a depth that you can make use of as you progress.
Getting a Python
If you want to try out Python then it couldn't be easier. Just go to www.python.org and download the version of Python you want to use.
This is our first problem.
Python comes in two distinct versions 2 and 3 and they aren't completely compatible. A decision was made to create a better version of Python even at the cost of making a non-compatible break with the current version. Python 3 was released on 3 December 2008 and at first it was difficult to know if you should use Python 2 or 3. Over time many of the incompatible elements in Python 3 were back ported to new version of Python 2 and the differences became less.
Now the choice of which Python to use is fairly obvious. If you don't have to work with legacy Python 2 code then learn Python 3. If you do have to work with legacy Python 2 code then learn Python 3 and convert the code to a only version of Python with a future.
Download the latest version of Python 3 and run the installer. Notice that if you are working with Linux then some distributions still use Python 2 as their default distribution - make sure to install the latest Python 3.
After installation is complete you can try Python out either by using the command line interpreter or the IDLE visual IDE which is installed automatically.
Eventually you most probably will want to move to a more complete IDE than IDLE and the only problem here is that there are lots to choose from. To get started however IDLE will do.
If you start IDLE you can try out your first Python program by simply typing in:
and you will see 4 displayed..
Python is an interpreted language and whatever you type in is obeyed at once. Python is dynamic and variables can be assigned to without any need to declare them first.
Built in variable types include integers, floating point, complex numbers, unlimited precision integers and strings.
Notice that already we are moving into some unusual areas – most languages don’t bother providing complex numbers or integers with as many digits as you like.
What is more, Python decides the type of variable needed according to what you try to store in it.
is integer and
is a long integer.
You also get all of the standard arithmetic operations and comparisons, plus some more interesting binary operations such as >> shift and xor but you can learn about these as you go along.
If you type any of these assignments into IDLE they will be executed. To see the result simply type the variable name and enter a return and IDLE will show you the contents of the variable.
The fundamental way of working with text in Python is to use a string.
Strings work much like they used to in Basic in that there is no equivalent to a fundamental character type – if you want to work with a single character just use a one-character string.
Strings support concatenation and slicing.
s = “Spam” + “Spam”
gives “SpamSpam” and
is a slice of the string from offset i up to but not including offset j.The first character of a string is at offset 0 so
gives S and
gives Sa and so on.
Negative offsets are from the right hand end of the string.
There are so many ways of writing slices and string operators in general that it deserves a complete chapter.
You can also use a repeat operator
is three times the amount of Spam i.e. SpamSpamSpam.
You can also make use of formatting operations very similar to the C formatting codes. For example, %%d formats a decimal integer into a string.
At this stage suffice it to say that Python has sufficient string handling to make most tasks relatively easy compared to the tricks you have to perform when using C or Java. The ability to handle text easily is one of Python's strong points.
More on strings in another chapter.
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Electrons in graphene superlattices are different and behave as neutrinos that acquired a notable mass. This results in a new, relativistic behaviour so that electrons can now skew at large angles to applied fields. The effect is huge.
This new membrane lasts twice as long when compared to conventional membranes, is highly resistant to breakage, and has anti-bacterial and anti-biofouling properties. Another groundbreaking characteristic - it allows for an unprecedented flow rate of at least ten times faster than current water filtration membranes.
In a first-of-its-kind demonstration, a team of researchers has developed a powerful technique to focus laser light through even the murkiest of surroundings without the need for a guide star. This innovation, a specialized version of an adaptive optics microscope, can resolve a point less than one thousandth of a millimeter across.
A team of Berkeley Lab researchers believes it has uncovered the secret behind the unusual optoelectronic properties of single atomic layers of transition metal dichalcogenide (TMDC) materials, the two-dimensional semiconductors that hold great promise for nanoelectronic and photonic applications.
Funding provided by the UK Research Partnership Investment Fund, the Technology Strategy Board and Masdar, an Abu Dhabi-based clean technology and renewable energy company University of Manchester and Masdar Institute to establish graphene commercial application programs.
Scientists have discovered a novel cause of glaucoma in an animal model, and related to their findings, are now developing an eye drop aimed at curing the disease. They believe their findings will be important to human glaucoma.
The surface of graphene, a one atom thick sheet of carbon, can be randomly decorated with oxygen to create graphene oxide; a form of graphene that could have a significant impact on the chemical, pharmaceutical and electronic industries. Applied as paint, it could provide an ultra-strong, non-corrosive coating for a wide range of industrial applications.
Misfolded proteins can lead to a variety of diseased states, including Alzheimer's and Parkinson's. Researchers have now developed a method with which one can synthesize hundreds of proteins and analyze their folding properties at once at the single-molecule level.
Scientists have for the first time used photothermal induced resonance (PTIR) to characterize individual plasmonic nanomaterials in order to obtain absorption maps and spectra with nanometer-scale resolution. Nanostructuring of plasmonic materials enables engineering of their resonant optical response and creates new opportunities for applications that benefit from enhanced light-matter interactions, including sensing, photovoltaics, photocatalysis, and therapeutics. | <urn:uuid:65c24233-7fe1-4bc1-ab63-ab034ff85ff8> | 2.765625 | 550 | Content Listing | Science & Tech. | 10.831649 | 95,566,528 |
Typhoon Nangka's strongest typhoon-force winds were located on the northern half of the storm, as identified from the RapidScat instrument that flies aboard the International Space Station.
RapidScat gathered surface wind data on the Typhoon Nangka on July 13 from 01:54 to 3:26 UTC (July 12, 9:54 p.m. to 11:26 p.m. EDT).
RapidScat data showed that the strongest sustained winds stretched from northwest to northeast of the center at speeds up to 36 meters per second (129 kph/80 mph).
On July 14 at 03:47 UTC the Atmospheric Infrared Sounder or AIRS instrument aboard NASA's Aqua satellite gathered infrared data on the typhoon. There were powerful thunderstorms with very cold cloud top temperatures surrounding the eye of the storm.
Temperatures colder than -63 Fahrenheit/-52 Celsius that indicated they were high into the troposphere. The image showed a clear area in the eye that allowed the infrared image to show a warmer lower altitude eyewall temperature.
On July 14 at 1500 UTC (11 a.m. EDT), Nangka had sustained winds near 90 knots (103.6 mph/166.7 kph). Those typhoon-force winds extended up to 65 miles from the center.
Nangka was located near 24.4 North latitude and 136.5 East longitude, about 637 nautical miles (733 miles/1,180 km) south-southeast of Iwakuni, Japan. Nangka was moving to the north at 7 knots (8 mph/12.9 kph).
Nangka is moving north and the Joint Typhoon Warning Center forecast calls for the storm to peak at 100 knots(115 mph/185 kph) by July 15. Nangka is then expected to turn west and weaken as it nears Japan. The current forecast track takes the storm to a landfall in western Japan.
Rob Gutro | EurekAlert!
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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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Cells divide to form two identical cells as part of the body’s natural development and replenishment processes but when cells divide in an abnormal manner, tumours can develop.
Research has shown that an enzyme called ‘Polo kinase’ is involved in normal cell division but that it also goes into overdrive in cancer helping cells to multiply in an uncontrolled way.
Clinical trials on drugs that block the actions of Polo kinase started in the United States last year but the complete picture of how the enzyme assisted the cell-division process has not been clear until now.
Writing in the highly respected science journal, Nature, a team of researchers from the Universities of Manchester and Newcastle-upon-Tyne have described a new way in which the enzyme works.
“Enzymes are proteins that speed up or ‘catalyse’ the body’s chemical reactions such as those required for normal cell division,” explained Professor Andrew Sharrocks, lead researcher in Manchester’s Faculty of Life Sciences.
“As its name suggests, the enzyme we have studied is from a group known as kinase enzymes which use a particular chemical – a phosphate – to catalyse the reactions that lead to cell division.
“Our study has identified a new target protein that uses these phosphate groups to switch on genes and alter the properties of cells.
“When the actions of enzymes like Polo kinase go unchecked, cells divide in an uncontrolled manner to form tumours. However, if we block their activity using chemical inhibitors the cells can no longer divide and the cancer cannot grow and spread.”
The identification of a new key step in which Polo kinase functions confirms the choice of this enzyme as a target for anti-cancer drug development and will spur on efforts in this direction.
Indeed, as scientists now have a much greater understanding of the mechanisms involved, it might enable them to either develop more effective drugs or suggest different situations in which the drug can be used.
“Kinase inhibitors are proving to be very effective at killing off rogue cells and trials on patients elsewhere have been promising with fewer toxic effects than current cancer treatments,” said Professor Sharrocks.
“Our research on Polo kinase will help with this line of drug development and hopefully produce more effective kinase-blocking chemicals that will one day treat patients with different types of cancer.”
Aeron Haworth | 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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Geophysics // is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term geophysics sometimes refers only to the geological applications: Earth's shape; its gravitational and magnetic fields; its internal structure and composition; its dynamics and their surface expression in plate tectonics, the generation of magmas, volcanism and rock formation. However, modern geophysics organizations use a broader definition that includes the water cycle including snow and ice; fluid dynamics of the oceans and the atmosphere; electricity and magnetism in the ionosphere and magnetosphere and solar-terrestrial relations; and analogous problems associated with the Moon and other planets.
Although geophysics was only recognized as a separate discipline in the 19th century, its origins date back to ancient times. The first magnetic compasses were made from lodestones, while more modern magnetic compasses played an important role in the history of navigation. The first seismic instrument was built in 132 AD. Isaac Newton applied his theory of mechanics to the tides and the precession of the equinox; and instruments were developed to measure the Earth's shape, density and gravity field, as well as the components of the water cycle. In the 20th century, geophysical methods were developed for remote exploration of the solid Earth and the ocean, and geophysics played an essential role in the development of the theory of plate tectonics.
Geophysics is applied to societal needs, such as mineral resources, mitigation of natural hazards and environmental protection. In Exploration Geophysics, Geophysical survey data are used to analyze potential petroleum reservoirs and mineral deposits, locate groundwater, find archaeological relics, determine the thickness of glaciers and soils, and assess sites for environmental remediation.
Geophysics is a highly interdisciplinary subject, and geophysicists contribute to every area of the Earth sciences. To provide a clearer idea of what constitutes geophysics, this section describes phenomena that are studied in physics and how they relate to the Earth and its surroundings.
The gravitational pull of the Moon and Sun give rise to two high tides and two low tides every lunar day, or every 24 hours and 50 minutes. Therefore, there is a gap of 12 hours and 25 minutes between every high tide and between every low tide.
Gravitational forces make rocks press down on deeper rocks, increasing their density as the depth increases. Measurements of gravitational acceleration and gravitational potential at the Earth's surface and above it can be used to look for mineral deposits (see gravity anomaly and gravimetry). The surface gravitational field provides information on the dynamics of tectonic plates. The geopotential surface called the geoid is one definition of the shape of the Earth. The geoid would be the global mean sea level if the oceans were in equilibrium and could be extended through the continents (such as with very narrow canals).
The Earth is cooling, and the resulting heat flow generates the Earth's magnetic field through the geodynamo and plate tectonics through mantle convection. The main sources of heat are the primordial heat and radioactivity, although there are also contributions from phase transitions. Heat is mostly carried to the surface by thermal convection, although there are two thermal boundary layers – the core-mantle boundary and the lithosphere – in which heat is transported by conduction. Some heat is carried up from the bottom of the mantle by mantle plumes. The heat flow at the Earth's surface is about 4.2 × 1013 W, and it is a potential source of geothermal energy.
Seismic waves are vibrations that travel through the Earth's interior or along its surface. The entire Earth can also oscillate in forms that are called normal modes or free oscillations of the Earth. Ground motions from waves or normal modes are measured using seismographs. If the waves come from a localized source such as an earthquake or explosion, measurements at more than one location can be used to locate the source. The locations of earthquakes provide information on plate tectonics and mantle convection.
Measurements of seismic waves are a source of information on the region that the waves travel through. If the density or composition of the rock changes suddenly, some waves are reflected. Reflections can provide information on near-surface structure. Changes in the travel direction, called refraction, can be used to infer the deep structure of the Earth.
Earthquakes pose a risk to humans. Understanding their mechanisms, which depend on the type of earthquake (e.g., intraplate or deep focus), can lead to better estimates of earthquake risk and improvements in earthquake engineering.
Although we mainly notice electricity during thunderstorms, there is always a downward electric field near the surface that averages 120 volts per meter. Relative to the solid Earth, the atmosphere has a net positive charge due to bombardment by cosmic rays. A current of about 1800 amperes flows in the global circuit. It flows downward from the ionosphere over most of the Earth and back upwards through thunderstorms. The flow is manifested by lightning below the clouds and sprites above.
A variety of electric methods are used in geophysical survey. Some measure spontaneous potential, a potential that arises in the ground because of man-made or natural disturbances. Telluric currents flow in Earth and the oceans. They have two causes: electromagnetic induction by the time-varying, external-origin geomagnetic field and motion of conducting bodies (such as seawater) across the Earth's permanent magnetic field. The distribution of telluric current density can be used to detect variations in electrical resistivity of underground structures. Geophysicists can also provide the electric current themselves (see induced polarization and electrical resistivity tomography).
Electromagnetic waves occur in the ionosphere and magnetosphere as well as the Earth's outer core. Dawn chorus is believed to be caused by high-energy electrons that get caught in the Van Allen radiation belt. Whistlers are produced by lightning strikes. Hiss may be generated by both. Electromagnetic waves may also be generated by earthquakes (see seismo-electromagnetics).
In the Earth's outer core, electric currents in the highly conductive liquid iron create magnetic fields by electromagnetic induction (see geodynamo). Alfvén waves are magnetohydrodynamic waves in the magnetosphere or the Earth's core. In the core, they probably have little observable effect on the geomagnetic field, but slower waves such as magnetic Rossby waves may be one source of geomagnetic secular variation.
The Earth's magnetic field protects the Earth from the deadly solar wind and has long been used for navigation. It originates in the fluid motions of the Earth's outer core (see geodynamo). The magnetic field in the upper atmosphere gives rise to the auroras.
The Earth's field is roughly like a tilted dipole, but it changes over time (a phenomenon called geomagnetic secular variation). Mostly the geomagnetic pole stays near the geographic pole, but at random intervals averaging 440,000 to a million years or so, the polarity of the Earth's field reverses. These geomagnetic reversals, analyzed within a Geomagnetic Polarity Time Scale, contain 184 polarity intervals in the last 83 million years, with change in frequency over time, with the most recent brief complete reversal of the Laschamp event occurring 41,000 years ago during the last glacial period. Geologists observed geomagnetic reversal recorded in volcanic rocks, through magnetostratigraphy correlation (see natural remanent magnetization) and their signature can be seen as parallel linear magnetic anomaly stripes on the seafloor. These stripes provide quantitative information on seafloor spreading, a part of plate tectonics. They are the basis of magnetostratigraphy, which correlates magnetic reversals with other stratigraphies to construct geologic time scales. In addition, the magnetization in rocks can be used to measure the motion of continents.
Radioactive decay accounts for about 80% of the Earth's internal heat, powering the geodynamo and plate tectonics. The main heat-producing isotopes are potassium-40, uranium-238, uranium-235, and thorium-232. Radioactive elements are used for radiometric dating, the primary method for establishing an absolute time scale in geochronology. Unstable isotopes decay at predictable rates, and the decay rates of different isotopes cover several orders of magnitude, so radioactive decay can be used to accurately date both recent events and events in past geologic eras. Radiometric mapping using ground and airborne gamma spectrometry can be used to map the concentration and distribution of radioisotopes near the Earth's surface, which is useful for mapping lithology and alteration.
Fluid motions occur in the magnetosphere, atmosphere, ocean, mantle and core. Even the mantle, though it has an enormous viscosity, flows like a fluid over long time intervals (see geodynamics). This flow is reflected in phenomena such as isostasy, post-glacial rebound and mantle plumes. The mantle flow drives plate tectonics and the flow in the Earth's core drives the geodynamo.
Geophysical fluid dynamics is a primary tool in physical oceanography and meteorology. The rotation of the Earth has profound effects on the Earth's fluid dynamics, often due to the Coriolis effect. In the atmosphere it gives rise to large-scale patterns like Rossby waves and determines the basic circulation patterns of storms. In the ocean they drive large-scale circulation patterns as well as Kelvin waves and Ekman spirals at the ocean surface. In the Earth's core, the circulation of the molten iron is structured by Taylor columns.
The physical properties of minerals must be understood to infer the composition of the Earth's interior from seismology, the geothermal gradient and other sources of information. Mineral physicists study the elastic properties of minerals; their high-pressure phase diagrams, melting points and equations of state at high pressure; and the rheological properties of rocks, or their ability to flow. Deformation of rocks by creep make flow possible, although over short times the rocks are brittle. The viscosity of rocks is affected by temperature and pressure, and in turn determines the rates at which tectonic plates move (see geodynamics).
Water is a very complex substance and its unique properties are essential for life. Its physical properties shape the hydrosphere and are an essential part of the water cycle and climate. Its thermodynamic properties determine evaporation and the thermal gradient in the atmosphere. The many types of precipitation involve a complex mixture of processes such as coalescence, supercooling and supersaturation. Some precipitated water becomes groundwater, and groundwater flow includes phenomena such as percolation, while the conductivity of water makes electrical and electromagnetic methods useful for tracking groundwater flow. Physical properties of water such as salinity have a large effect on its motion in the oceans.
Regions of the EarthEdit
Size and form of the EarthEdit
The Earth is roughly spherical, but it bulges towards the Equator, so it is roughly in the shape of an ellipsoid (see Earth ellipsoid). This bulge is due to its rotation and is nearly consistent with an Earth in hydrostatic equilibrium. The detailed shape of the Earth, however, is also affected by the distribution of continents and ocean basins, and to some extent by the dynamics of the plates.
Structure of the interiorEdit
Evidence from seismology, heat flow at the surface, and mineral physics is combined with the Earth's mass and moment of inertia to infer models of the Earth's interior – its composition, density, temperature, pressure. For example, the Earth's mean specific gravity (5.515) is far higher than the typical specific gravity of rocks at the surface (2.7–3.3), implying that the deeper material is denser. This is also implied by its low moment of inertia ( 0.33 M R2, compared to 0.4 M R2 for a sphere of constant density). However, some of the density increase is compression under the enormous pressures inside the Earth. The effect of pressure can be calculated using the Adams–Williamson equation. The conclusion is that pressure alone cannot account for the increase in density. Instead, we know that the Earth's core is composed of an alloy of iron and other minerals.
Reconstructions of seismic waves in the deep interior of the Earth show that there are no S-waves in the outer core. This indicates that the outer core is liquid, because liquids cannot support shear. The outer core is liquid, and the motion of this highly conductive fluid generates the Earth's field (see geodynamo). The inner core, however, is solid because of the enormous pressure.
Reconstruction of seismic reflections in the deep interior indicate some major discontinuities in seismic velocities that demarcate the major zones of the Earth: inner core, outer core, mantle, lithosphere and crust. The mantle itself is divided into the upper mantle, transition zone, lower mantle and D′′ layer. Between the crust and the mantle is the Mohorovičić discontinuity.
The seismic model of the Earth does not by itself determine the composition of the layers. For a complete model of the Earth, mineral physics is needed to interpret seismic velocities in terms of composition. The mineral properties are temperature-dependent, so the geotherm must also be determined. This requires physical theory for thermal conduction and convection and the heat contribution of radioactive elements. The main model for the radial structure of the interior of the Earth is the preliminary reference Earth model (PREM). Some parts of this model have been updated by recent findings in mineral physics (see post-perovskite) and supplemented by seismic tomography. The mantle is mainly composed of silicates, and the boundaries between layers of the mantle are consistent with phase transitions.
The mantle acts as a solid for seismic waves, but under high pressures and temperatures it deforms so that over millions of years it acts like a liquid. This makes plate tectonics possible. Geodynamics is the study of the fluid flow in the mantle and core.
If a planet's magnetic field is strong enough, its interaction with the solar wind forms a magnetosphere. Early space probes mapped out the gross dimensions of the Earth's magnetic field, which extends about 10 Earth radii towards the Sun. The solar wind, a stream of charged particles, streams out and around the terrestrial magnetic field, and continues behind the magnetic tail, hundreds of Earth radii downstream. Inside the magnetosphere, there are relatively dense regions of solar wind particles called the Van Allen radiation belts.
Geophysical measurements are generally at a particular time and place. Accurate measurements of position, along with earth deformation and gravity, are the province of geodesy. While geodesy and geophysics are separate fields, the two are so closely connected that many scientific organizations such as the American Geophysical Union, the Canadian Geophysical Union and the International Union of Geodesy and Geophysics encompass both.
Absolute positions are most frequently determined using the global positioning system (GPS). A three-dimensional position is calculated using messages from four or more visible satellites and referred to the 1980 Geodetic Reference System. An alternative, optical astronomy, combines astronomical coordinates and the local gravity vector to get geodetic coordinates. This method only provides the position in two coordinates and is more difficult to use than GPS. However, it is useful for measuring motions of the Earth such as nutation and Chandler wobble. Relative positions of two or more points can be determined using very-long-baseline interferometry.
Gravity measurements became part of geodesy because they were needed to related measurements at the surface of the Earth to the reference coordinate system. Gravity measurements on land can be made using gravimeters deployed either on the surface or in helicopter flyovers. Since the 1960s, the Earth's gravity field has been measured by analyzing the motion of satellites. Sea level can also be measured by satellites using radar altimetry, contributing to a more accurate geoid. In 2002, NASA launched the Gravity Recovery and Climate Experiment (GRACE), wherein two twin satellites map variations in Earth's gravity field by making measurements of the distance between the two satellites using GPS and a microwave ranging system. Gravity variations detected by GRACE include those caused by changes in ocean currents; runoff and ground water depletion; melting ice sheets and glaciers.
Satellites and space probesEdit
Satellites in space have made it possible to collect data from not only the visible light region, but in other areas of the electromagnetic spectrum. The planets can be characterized by their force fields: gravity and their magnetic fields, which are studied through geophysics and space physics.
Measuring the changes in acceleration experienced by spacecraft as they orbit has allowed fine details of the gravity fields of the planets to be mapped. For example, in the 1970s, the gravity field disturbances above lunar maria were measured through lunar orbiters, which led to the discovery of concentrations of mass, mascons, beneath the Imbrium, Serenitatis, Crisium, Nectaris and Humorum basins.
Geophysics emerged as a separate discipline only in the 19th century, from the intersection of physical geography, geology, astronomy, meteorology, and physics. However, many geophysical phenomena – such as the Earth's magnetic field and earthquakes – have been investigated since the ancient era.
Ancient and classical erasEdit
The magnetic compass existed in China back as far as the fourth century BC. It was used as much for feng shui as for navigation on land. It was not until good steel needles could be forged that compasses were used for navigation at sea; before that, they could not retain their magnetism long enough to be useful. The first mention of a compass in Europe was in 1190 AD.
In circa 240 BC, Eratosthenes of Cyrene deduced that the Earth was round and measured the circumference of the Earth, using trigonometry and the angle of the Sun at more than one latitude in Egypt. He developed a system of latitude and longitude.
Perhaps the earliest contribution to seismology was the invention of a seismoscope by the prolific inventor Zhang Heng in 132 AD. This instrument was designed to drop a bronze ball from the mouth of a dragon into the mouth of a toad. By looking at which of eight toads had the ball, one could determine the direction of the earthquake. It was 1571 years before the first design for a seismoscope was published in Europe, by Jean de la Hautefeuille. It was never built.
Beginnings of modern scienceEdit
One of the publications that marked the beginning of modern science was William Gilbert's De Magnete (1600), a report of a series of meticulous experiments in magnetism. Gilbert deduced that compasses point north because the Earth itself is magnetic.
In 1687 Isaac Newton published his Principia, which not only laid the foundations for classical mechanics and gravitation but also explained a variety of geophysical phenomena such as the tides and the precession of the equinox.
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- A reference manual for near-surface geophysics techniques and applications
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- Union Commissions (IUGG)
- USGS Geomagnetism Program
- Career crate: Seismic processor
- Society of Exploration Geophysicists | <urn:uuid:f8692a10-8fc5-4566-96a1-e5f414360776> | 3.421875 | 6,280 | Knowledge Article | Science & Tech. | 46.765824 | 95,566,586 |
Introduction to Molecular Genetics and Recombinant DNA Technology
The basic repositories of biological information flow, called genes, consist of molecules of DNA. Molecular biologists attempt to understand the molecular basis for the flow and regulation of genetic information by using recombinant DNA methods to isolate and analyze genes. The ability of molecular biology to examine genes directly is revolutionizing the study of virtually all biological systems, including many areas relevant to transfusion medicine. This communication attempts to introduce the basic concepts of this field. For nearly two decades after the elucidation of the crystallographic structure of DNA, molecular geneticists were largely confined to the study of simple microorganisms. Complex genomes were beyond the capability of the limited repertoire of methods available for manipulating DNA molecules until a new approach, recombinant DNA technology, arose in the 1970’s. Recombinant DNA methods combine advances in enzymology, nucleic acid biochemistry, and microbial genetics in ways that allow one to ‘cut and paste’ DNA molecules from diverse sources together to form novel DNA molecules and to introduce this DNA into new host cells, where it can be propagated and expressed. These capabilities permit one to physically isolate or ‘clone’ individual genes even if they originally represent only one part per million or less of a complex genome.
KeywordsMolecular Hybridization Sugar Phosphate Backbone Double Stranded Helix Strand Coil Single Stranded cDNA Template
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Cosmic Scale Factor
Cosmic Scale Factor is a function of time which represents the relative expansion of the universe. It relates the comoving distances for an expanding universe with the distances at a reference time arbitrarily taken to be the present.
- What is Cosmology?
- The Speed of Light
- Redshift and Blueshift
- What is the Cosmic Microwave Background Radiation?
- Cosmic Scale Factor
- The Physics Governing the Universe
- The Nature of Light
- The Four Forces in the Universe
- The Expansion of the Universe
- The Importance of Cosmic Background Radiation in Modern Cosmology
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The distance between any two objects is changing over time due to the expansion of the universe. When we look at a distant object, we are effectively looking back through time, since the speed of light is finite and takes a time to reach us. For example, when we look at the Sun, we see it as it was 8 minutes ago. When we look at the Andromeda galaxy, the light has taken about 2.2 million years to get to our galaxy, so we see the Andromeda galaxy as it was 2.2 million years ago. This relationship between time and distance is called Cosmic Scale Factor.
To compare distances and sizes from different times is not easy since we must remove the effects of expansion. In this article, we are going to assume a flat geometry to the universe.
Consider left hand image in the graphic above. This represents an arbitrary point in time in the past (t1). We can see a galaxy at point (0,0) and another one at point (3,2). These points are comoving coordinates. Simple trigonometry tells us that the distance between the two comoving coordinates is 3.6 units (a2 = b2 + c2).
Now consider the image to the right. This represents another point in time, let's say it's the present (t0). The galaxies are still at the same coordinates, and the distance is still 3.6 units, but we can clearly see that they are separated by a larger distance. We can also see that the longer intervals have also expanded with time.
There are two possible definitions of a comoving coordinates, and both are used in cosmology. Unfortunately, the same symbol r is often used for both. Comoving distance coordinates are used as follows.
- The comoving radial distance coordinate for calculating proper distances between objects at two different epochs (i.e. large time separation).
- The comoving angular diameter distance coordinate for calculating proper distances between two objects at the same epoch.
The coordinates are exactly that - coordinates. They are not distances, but proper distance may be calculated from them. Think of comoving coordinates as labels attached to the galaxies for all time. Different galaxies have different comoving coordinates, but a particular galaxy keeps the same comoving coordinates forever. Using comoving coordinates, we are able to describe the position of any object independently of expansion.
We can define the proper distance x(t), corresponding to different times, in terms of the comoving radial distance coordinate r using the equation:
Equation 35 - Proper Distance
The notation R(t) indicates that the cosmic scale factor is a function of time and its value changes with time (epoch).
In an expanding universe, the scale factor R(t) corresponding to a past epoch is smaller than 1, and greater than 1 for future epochs. A scale factor of 1 represents the current epoch (now)
- R(t) < 1 in past
- R(t) = 1 now
- R(t) > 1 in future
The behaviour of the cosmic scale factor R(t) with time tells how the universe itself evolves with time. Knowing this we can construct a relationship between redshift and the scale factor for another epoch.
Equation 36 - Redshift and Scale Factor
This shows that the redshift can be used to specify the size of the universe relative to the size today. Astronomers and cosmologists talk about redshifts of objects rather than distances or emission epochs.
Worked example of Cosmic Scale Factor
A distant galaxy has been analysed and it was found that it has a redshift of z = 2. What was the size of the universe at the time when the light left the galaxy relative to the size of the universe now?
Equation 37 - Scale factor worked
Thus the linear size of the universe was one-third of what it is now.
The Hubble Constant
The Hubble Constant (H0) gives a value for the expansion rate of the universe. This expansion rate is equal to the rate of the change of the scale factor.
The rate of change in scale factor it is given the symbol
The dot above the R is the mathematical notation for "rate of change". Using the comoving radial distance coordinate, r, we can derive the expansion "velocity" v:
which is Hubble's law with
So the Hubble "constant" is actually time-dependent, and its value can be determined by the measurement of redshifts and distances to galaxies.
Last updated on: Wednesday 17th January 2018
The the afterglow from the early universe and evidence for the Big Bang theory
A look at the mysterious Gamma Ray Bursts, where they come from and what hey mean for astronomy | <urn:uuid:2f23f019-db38-4c2b-a20f-905f729d9bce> | 3.609375 | 1,127 | Knowledge Article | Science & Tech. | 44.950492 | 95,566,589 |
Comets are highly unpredictable, which is one aspect which makes them so interesting to observe; their appearance can change from night to night, and each comet is different. Around twenty comets are usually discovered or recovered each year; of these, perhaps four will come within the range of amateur instruments.
KeywordsSolar Wind Pupil Diameter Variable Star Comparison Star Faint Star
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- Yeomans D, Comets, John Wiley (1991).Google Scholar | <urn:uuid:902616bf-8e73-4eb6-95aa-de4d0007994a> | 3.25 | 174 | Truncated | Science & Tech. | 43.208092 | 95,566,591 |
University of Virginia researchers have found that the very simple eyes of fruit fly larvae, with only 24 total photoreceptors (the human eye contains more than 125 million), provide just enough light or visual input to allow the animal’s relatively large brain to assemble that input into images.
“It blows open how we think about vision,” said Barry Condron, a neurobiologist in U.Va.’s College of Arts & Sciences, who oversaw the study. “This tells us that visual input may not be as important to sight as the brain working behind it. In this case, the brain apparently is able to compensate for the minimal visual input.”
Condron’s graduate students, Elizabeth Daubert, Nick Macedonia and Catherine Hamilton, conducted a series of experiments to test the vision of fruit fly larvae after they noticed an interesting behavior of the animals during a different study of the nervous system. They found that when a larva was tethered to the bottom of a petri dish, other larvae were attracted to it as it wiggled attempting to free itself.
The animals apparently saw the writhing motion and were attracted to it, willingly traveling toward it. After several further experiments to understand how they sensed the motion, the researchers learned that the nearly blind animals likely were seeing the action, by wagging their heads side-to-side in a scanning motion to detect it, rather than by only hearing it or feeling vibration or by smelling the trapped larva. This was a surprise because of the very simple and limited vision of fruit fly larvae.“The answer must be in the large, somewhat sophisticated brain of these animals,” Condron said. “They are able to take just a couple dozen points of light and then process that into recognizable images; something like when an astronomer with a small telescope is able to use techniques to refine a limited image into useful information about a star.”
Condron believes the animals are able to assemble useful images by rapidly scanning their heads and, in so doing, gather up enough light points to allow the brain to compose a panoramic image clear enough to “see.”
“Apparently they are – to a very high degree – visually sensitive to detail and rate of motion and can recognize their own species in this way,” Condron said. “This provides us with a good model for trying to understand the role that the brain plays in helping organisms, including humans, to process images, such as recognizing faces.”
He noted that the head scanning apparently plays an important role in helping the larvae to bring together multiple visual inputs into a unified whole for the brain to process, similar to collecting together multiple pixels to form a picture. Condron said people with severe vision loss also tend to use head scanning as a means for collecting a “picture” from very dim light sources. Likewise, visually impaired people who have received experimental retinal implants of just a small number of pixels also often scan their heads to take in enough light to form mental images.
“It’s easy for lab biologists to view fruit flies as simple animals that just feed and reproduce, but we are beginning to realize that that may be in contradiction to the big brain,” Condron said. “There’s more to what they are able to do than previously thought, whether using that brain for behaviors or for constructing images from a limited visual system.”
He said the fruit fly serves as an excellent model for studying neurons because the animal has only about 20,000 of them, whereas humans have about 100 billion. Yet there are many similarities to how fruit fly and human neurons work. According to Condron, researchers are within a year of mapping the entire nervous system of the fruit fly, which then will pave the way for greater understanding of how neurons work in a range of organisms, including humans.
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- Scientists at the London Research Institute of Cancer Research UK use the Linkam CMS196 for Imaging Mammalian Cells with Cryo-CLXM Microscopy
Product News: Scientists at the London Research Institute of Cancer Research UK use the Linkam CMS196 for Imaging Mammalian Cells with Cryo-CLXM MicroscopyFor mammalian cells to remain in a healthy state, they require constant renewal of their components. The process of disposing of old components is known as 'autophagy', which stems from the Greek words auto "self" and phagein "eat". This process involves the formation of a double-membrane structure called an autophagosome, which engulfs old or dysfunctional organelles and then fuses with lysosomes, where they are broken down to recycle the constituent molecules. Autophagy is increased when cells are starved, and plays a fundamental role in a large number of cellular processes, including development, immunity, neurodegeneration and cancer.
In a recent publication in the journal, Ultramicroscopy (Duke et al., 2013), Dr. Lucy Collinson (LRI Electron Microscopy Unit), in collaboration with Dr. Sharon Tooze (LRI Secretory Pathways Lab), imaged forming autophagosomes in whole mammalian cells. The structures are particularly difficult to capture in cells prepared for electron microscopy, so they are now using a powerful new technique called cryo-soft X-ray tomography, cryo-SXT, working with Dr. Liz Duke at the Diamond Light Source synchrotron. This allows whole mammalian cells to be imaged as close to the living state as possible. The cells are grown on tiny gold grids and plunged into liquid ethane to preserve the cells in the frozen state.
In order to find the autophagosomes within the cells, they are labeled with green fluorescent protein (GFP). The fluorescent autophagosomes are then located using a technique called correlative cryo-fluorescence and cryo-soft x-ray microscopy (cryo-CLXM). Cryo-fluorescence microscopy is performed using the Linkam CMS196 stage prior to the cells being transported in cryo-containers to synchrotrons in Oxfordshire, Berlin and Barcelona for imaging. One of the major advantages of this new correlative approach is that the CMS196 stage allows the cells to be screened for quality and protein localization in the research laboratory before actually travelling to the synchrotron, which is critical in terms of cost and efficiency. The combination of cryo-fluorescence microscopy and cryo-SXT allows scientists to link the functionality of proteins to their near native-state structure. This should find wide applications in cell biology studies of health and disease.
The Linkam CMS196 stage was designed specifically to solve the problem of how to get vitrified EM grids from the fluorescence microscope into the cryo-TEM without devitrification and contamination through condensation. The stage has been optimized optically to enable the use of high NA lenses. Up to 3 grids can be loaded into a specially designed cassette for transportation from the plunge freezer to the upright fluorescent microscope. The cassette is then easily loaded onto the viewing bridge using special manipulation tools. The sample viewing chamber is perfectly dry and below -180ºC while the sample bridge itself is at -196°C. The grids can be quickly and efficiently scanned using a 100X 0.75NA lens and manipulated using high precision micrometers. The cassette is then simply manipulated back into the transportation device and is then transported to the cryo-TEM under liquid nitrogen. | <urn:uuid:12b6d5a4-f691-4185-b430-224a4d07661c> | 2.734375 | 745 | Product Page | Science & Tech. | 30.81917 | 95,566,596 |
Silver nanoparticles (AgNPs) are known to have excellent antibacterial properties and are considered by many to be a strong contender in the critical search for an answer to antibiotic-resistant bacteria. They block enzymes and can cause bacteria to have irregularly shaped membranes, producing results ranging from inhibited growth to cell death. However, a collaboration of researchers from Kumamoto University, Keio University, and Dai Nippon Toryo Co., Ltd. in Japan found that AgNPs have a propensity to conglomerate, which results in a reduction of antibacterial attributes. They solved the conglomeration problem by coating the nanoparticles with gold. Unfortunately, this also caused a reduction of the antibacterial effects since the silver was no longer exposed. This prompted the researchers to search for a method to keep the shape of the nanoparticles as well as the antibacterial properties.
Pulsed laser irradiation on the gold-coated silver nanoparticles (Ag@Au NPs) provided a solution to the problem. When Ag@Au NPs are irradiated with a pulse laser, the morphology of the NPs changes from a triangular plate to a spherical shape. This is due to the metals melting from the heat of the laser pulse.
The researchers showed that Ag@Au NPs were about half triangular and half spherical before irradiation but jumped to 94% spherical after irradiation. Furthermore, the silver-to-gold ratio of the pre-irradiation Ag@Au NPs was around 22:1, but the post-irradiation ratio was near 4.5:1.
This was interpreted by the researchers as the generation of defects in the gold-coating which allowed for some of the silver to escape as ions. This is an important aspect of the pulsed laser irradiation process since the release of silver produces the bactericidal effect.
"We have developed a method to activate the antibacterial properties of silver nanoparticles at will," said Professor Takuro Niidome, leader of the research group. "Our experiments have shown that, while non-irradiated gold-coated silver nanoparticles have only minor antibacterial properties, the effects are significantly increased after pulsed laser irradiation.
We hope to develop this technology further as a method of managing bacteria that have developed antibacterial resistance."
The irradiated Ag@Au NPs were highly effective against Escherichia coli, resulting in a 0% colony survival rate. Silver NPs alone were similarly effective, but the Ag@Au NPs had the advantages of being activated as needed and did not tend to clump together like the silver NPs.
This research was posted online in the Royal Society of Chemistry journal Nanoscale on 11 October 2017.
Kyaw, K., Ichimaru, H., Kawagoe, T., Terakawa, M., Miyazawa, Y., Mizoguchi, D., Tsushida, M, Niidome, T. (2017). Effects of pulsed laser irradiation on gold-coated silver nanoplates and their antibacterial activity. Nanoscale. doi:10.1039/c7nr06513b
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Snowshoe hares have an interesting adaptation that helps protect them against predators. Depending on the season, their fur can be a different color. During the winter, snowshoe hares are white, which helps them blend in with the snow. When the seasons change to spring and summer, snowshoe hares turn a reddish-brown. This color helps them camouflage with dirt and rocks.
Not every part of the snowshoe hare changes color throughout the year. An important identification trick is to look at a snowshoe hare's ears. The tips of the ears are always black no matter the season.
The hind legs of a snowshoe hare are noticeably larger, and have more fur and larger toes than those of other rabbits or hares. These adaptations provide additional surface area and support for walking on snow. The hind legs are what give the hare its common name.
Snowshoe hares live in the coniferous and boreal forests of the Rocky Mountains, the Appalachian Mountains, the Pacific Northwest, New England, Alaska, Minnesota, Michigan, and Montana. Within the United States, most of these coniferous forests are found on mountaintops, such as the Rockies, or near the Canadian border.
Snowshoe hares can be seen foraging among the brush. They eat mostly plants, enjoying grasses, flowers, and new growth from trees.
Snowshoe hares are nocturnal, so they're more likely to be seen at dawn and dusk. These animals have acute hearing and are able to detect predators.
Snowshoe hares breed in spring and summer. Females have a gestation period of roughly one month, and can give birth to up to eight young. A female hare can birth up to four litters a year.
The hares reach maturity after one year. Many hares do not live this long. But some hares can live as long as five years in the wild.
Snowshoe hares are common throughout their range. Because they are able to breed so rapidly, their populations are able to grow quickly.
Hares and rabbits are related, but there are some key differences. Hares tend to be larger than rabbits and have longer legs and bigger ears. When threatened, rabbits typically freeze and rely on camouflage, as compared to hares, who use their big feet to flee at the first sign of danger. Rabbits are born blind and helpless, while hares are born fully furred and ready to run.
Animal Diversity Web, University of Michigan Museum of Zoology
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Researchers capture nanoscale images of magnetic domains with laser as ultrashort flash
Just like flash photography can “freeze” and capture the motion of a child running in a dimly lit room, lasers can freeze motion as fast as electrons orbiting atoms. In a process called high-harmonic generation (HHG), lasers can form extremely short pulses with wavelengths down to one nanometer, which would enable observation in slow motion of a movie with nanometric-spatial and femtosecond-temporal resolution – one millionth of a millimeter and one millionth of a billionth of a second.
An image of worm-like magnetic domains in the sample, retrieved algorithmically from the scattered light.
Photo: University of Göttingen
A research team at the Universities of Göttingen and Augsburg in Germany in collaboration with Technion in Israel have now used femtosecond HHG pulses for the first time to capture images of magnetic domains. Published in the open-access journal Science Advances, the work establishes a highly-sought after technology: magneto-optical nano-imaging in a table-top scheme.
Magnetic orientation at the nanoscale has immense technological importance, serving as a basis for new generations of storage and logic devices. Understanding and controlling dynamic microscopic phenomena requires means to image rapid magnetic phenomena, such as switching processes.
Circularly polarized light is sensitive to the magnetization of materials and can thus be used to conduct microscopy of magnetic structures. Unfortunately, in order to achieve a resolution in the relevant range of a few tens of nanometers, very short wavelength is required. As a result, corresponding high-resolution microscopes previously required x-radiation from large particle accelerators such as synchrotrons and free-electron lasers.
The researchers addressed the long-standing challenge of achieving magnetic imaging with nanometric resolution using a laboratory-scale source of short-wavelength pulses of light, namely high harmonics. Importantly, the image resolution they reached, below 50 nm, is competitive with the resolution achievable in large accelerators.
The first key ingredient was the use of circularly-polarized high harmonics, for which a technique recently developed at Technion was employed. Moreover, as the magnetization-related signal is much smaller than typical non-magnetic effects, identifying the magnetic contrast may be described as searching for a needle in a haystack.
However, the team employed a trick that enhances the magnetic signal: Part of the light beam passed through and scattered off the magnetic sample, while another part was guided through auxiliary channels nearby. The interference between the magnetically scattered light and the light passing the channels increased the signal approximately 10-fold. Combining the auxiliary illumination with a control of the circular polarization rotation (clockwise or anti-clockwise) amplified and isolated the weak magnetic scattering – loosely speaking, making the “hidden needle” glow.
The team, led by Professor Claus Ropers in Göttingen, believe that numerous aspects may benefit from their demonstrated imaging approach. “Imaging is a very basic and versatile use of light,” says author Dr. Ofer Kfir. “Polarization contrast in light microscopy is already very powerful. Much higher resolutions are now possible by the shorter wavelengths, and this really gives us new access to nanoscale phenomena in magnetism and other areas.
The concept of signal enhancement by auxiliary light reduces the requirements on a source’s brightness, which makes the approach even more widely applicable.” Author Dr. Sergey Zayko notes another immediate goal for the future: “In addition, the femtosecond pulse duration of the HHG source will provide us with direct ultrafast movies of magnetic phenomena on the nanoscale.”
Original publication: Kfir, Zayko et al. Nanoscale magnetic imaging using circularly polarized high-harmonic radiation. Science Advances December 2017. Doi: 10.1126/sciadv.aao4641.
Dr. Ofer Kfir and Dr. Sergey Zayko
University of Göttingen
Faculty of Physics – 4th Physical Institute and Institute for X-ray Physics
Friedrich-Hund-Platz 1, 37077 Göttingen, Phone +49 551 39-12240
Emails: firstname.lastname@example.org, email@example.com
Thomas Richter | idw - Informationsdienst Wissenschaft
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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Found most commonly in these habitats: 17 times found in Wet sclerophyll, 15 times found in Rainforest, 7 times found in Dry sclerophyll, 5 times found in wet sclerophyll/rainforest, 6 times found in Eucalyptus forest, 3 times found in Rainforest edge, 3 times found in Wet sclerophyll forest, 0 times found in pine forest, 0 times found in Brigalow, 1 times found in Tropical rainforest, ...
Found most commonly in these microhabitats: 9 times random ground foragers, 8 times random foragers, 1 times random foragers on low vegetation, 2 times Ground foragers, 0 times foraging on ground, 1 times foraging on base of tree, 1 times foragers on low vegetation, 1 times Bymier picnic area random ground foragers, 2 times Stray ground foragers, 1 times random foragers in leaf litter, tree trunks, 1 times random foragers along edge of rock, ...
Collected most commonly using these methods: 6 times Pitfall, 0 times light trap, 3 times at u.v. light, 0 times flight intercept trap, 0 times M.V. Light Trap, 0 times Pyrethrum, 1 times at UV light, 0 times Pitfall 86, 0 times yellow trays, 1 times at honey bait.
Elevations: collected from 3 - 1500 meters, 511 meters average
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The relationships between a number of environmental variables and the daily sea trout (Salmo trutta L.) smolt output in the Burrishoole system were examined between 1971 and 2000. The average number of smolts migrating each year in the Burrishoole system decreased significantly from 3814 in the 1970s and 3899 in the 1980s to 1520 in the 1990s. A historic low of 769 smolts was recorded in the year 2000. The annual smolt runs were divided into a number of points, the duration in days to the 5, 50 and 95% points of the run. All of the points took substantially longer to reach in the 1980s and 1990s than in the 1970s, and they occurred earlier in the year. Sea trout smolt runs have shifted from discrete well-defined periods in the 1970s to more spread out less distinct runs in the 1990s. Two sets of environmental variables were identified as having an important role in smolt migration, regulating factors and controlling factors. Regulating factors operate before the smolt run and affect the physiological process of smoltification. The primary regulating factors were photoperiod and temperature. Controlling factors operate within the smolt run, affect the physical process of migration. The primary controlling factor was absolute water level, followed by change in water level, temperature and photoperiod. It is likely that the significant decline in the number of smolts migrating from the Burrishoole system over the period also had some effect on the dynamics of the smolt run. © 2003 Elsevier B.V. All rights reserved.
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I have heard on the news that the earthquake was so powerful that it changed the earth's rotation and axis by a small degree. I heard a similar story about the Indonesian earthquake.
Does anyone know:
1. what is the cumulative effect of both earthquakes on the length of the day and the earth's axis tilt
2. will the change have any effect on climate? I am thinking that even a small shift in the axis would have a noticeable effect on the polar regions.
some reports said our day was shortened by a fraction of a second. Axis moved by around 25 cm & parts Japan's coast moved closer to US by 2.4 m (8 ft)
I would really like to know how they determine these things.
I heard the day was shortened by 4 minutes (one day or every day? they didn't say)
The Axis - I don't remember exactly, but I think it was 4 cm or inches.
And, I heard Japan moved West by 13 feet. (not just the coast, the entire country!)
It happens because the earth's crust has been forced up by a few feet over a vast area as the Pacific plate has slipped under the Japanese one. My understanding is that it throws out the speed of the earth's spin from the norm because it shifts the distribtion of the Earth's mass. i.e. the mass is further from the centre of the globe.
I'm aware I haven't done a very good job of explaining that, for a former earth-sciences student!
Oh, and incidentally, they measure it using super accurate atomic clocks. It wont be enough for us to notice it!
It just increased the earth's rotation speed by 1 microsecond or 1/1000000 of a second. The the length of the day was decreased by 1/1000000 of a second. I do not think anyone will notice that. This effect will not change anything. The axis was shifted by about a degree and then resets itself because the moon is responsible for keeping the earth's axis at the 23 degrees tilt. The moon also stabilizes the earth's axis so it pretty much keeps it in its current orientation. These effects are extremely small to cause any significant change in our weather system
As usual, the BBC has managed to answer this in a more succinct way than me!
by John B Badd 12 months ago
I am not asking about the effect of burning oil or spilling it in the ocean. I am looking to find out how removing oil from the ground effects the ecosystem. Imagine we drained it and did not use it or spill it if it would help put you in the mind state for this forum.The way I...
by ngureco 7 years ago
Climate - Why Do We Have Different Seasons?
by ptosis 2 years ago
Climate change: Is that why the Earth's axis is shifting?Or is it the other way around? https://youtu.be/qab-zntCQ7Q The slow precession of the earth's wobble is called the Great, Cosmic or Platonic year and equals 25,860 earth's years. Now it is being said that there is a 'wobble...
by Jenn 16 months ago
Has anyone had any paranormal experiences, whether they've seen or heard a spirit- or any other unexplained activity?I haven't had any as of yet. However, my mom says that she saw her father in church after he died, and we also smelled his cologne around the house. Also, my sister claims to have...
by Sweetsusieg 7 years ago
Has anyone ever heard of Gather? It's another social networking site?There are so many social networking sites and some pay actual money for using them, just wondering if anyone has heard of it and how it's working for you.
by Beth37 4 years ago
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Photosynthetic assimilation of atmospheric carbon dioxide by land plants offers the underpinnings for terrestrial carbon (C) sequestration. A proportion of the C captured in plant biomass is partitioned to roots, where it enters the pools of soil organic C and soil inorganic C and can be sequestered for millennia. Bioenergy crops serve the dual role of providing biofuel that offsets fossil-fuel greenhouse gas (GHG) emissions and sequestering C in the soil through extensive root systems. Carbon captured in plant biomass can also contribute to C sequestration through the deliberate addition of biochar to soil, wood burial, or the use of durable plant products. Increasing our understanding of plant, microbial, and soil biology, and harnessing the benefits of traditional genetics and genetic engineering, will help us fully realize the GHG mitigation potential of phytosequestration.
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Proposed the atomic theory. Stated that all matter was composed of small indivisible particles called atoms, atoms of a given element possess unique characteristics, and three types of atoms exist: simple (elements), compound (simple molecules), and complex (complex molecules).
Discovered that atoms have positive charges.
Discovered the electron.
Announced idea that energy emitted by a resonator could only take on discrete values, with v being the energy for a resonator of frequency in hv, and h being the universal constant, now known as Planck’s constant.
Used the falling drop method to accurately determined the charge of an electron
Rutherford model of atom which explained that a small positively-charged nucleus was orbited by electrons.
Published model of the atomic structure. Became basis of the quantum theory.
Discovered systematic relation between wavelength and atomic number. Now known as Moseley’s Law.
Proposed special theory of relativity. States that matter and energy are one through the formula E=mc squared.
Discovered wave nature of electrons and suggested that all matter have wave properties.
Discovered Schrodinger wave equation which stated that the quantum state of a physical system changes over time.
Proposed the uncertainty principle. States that you cannot determine the position and velocity of a subatomic particle at the same time.
Discovered the neutron.
Invented the electrophorus.
Discovered law of conservation of mass.
Discovered induction of electric currents and constructed first electric dynamo.
Discovered pasteurization process.
Obtained patent for dynamite.
Discovered natural radioactivity.
Discovered polonium and radium.
Proved that wireless waves were not affected by the curvature of the Earth.
Produced the first television transmission.
Created nylon, a synthetic replacement of silk.
Created first successful controlled nuclear chain reaction.
Developed polymerase chain reaction.
Discovered by Chinese Admiral Cheng Ho
event that sparked WWI
Japans attack againsted U.S. durring WWII | <urn:uuid:4ba6eb97-812c-4777-95b9-e9779bed0175> | 3.59375 | 429 | Structured Data | Science & Tech. | 21.903355 | 95,566,749 |
New software developed with help from the Wildlife Conservation Society will allow tiger researchers to rapidly identify individual animals by creating a three-dimensional model using photos taken by remote cameras. The software, described in an issue of the journal Biology Letters, may also help identify the origin of tigers from confiscated skins.
The new software, developed by Conservation Research Ltd., creates a 3D model from scanned photos using algorithms similar to fingerprint-matching software used by criminologists.
The study's authors include Lex Hiby of Conservation Research Ltd., Phil Lovell of the Gatty Marine Laboratory's Sea Mammal Research Unit, and Narendra Patil, N. Samba Kumar, Arjun N. Gopalaswamy and K. Ullas Karanth all of the Wildlife Conservation Society's India Program.
Researchers currently calculate tiger populations by painstakingly reviewing hundreds of photos of animals caught by camera "traps" and then matching their individual stripe patterns, which are unique to each animal. Using a formula developed by renowned tiger expert Ullas Karanth of WCS, researchers accurately estimate local populations by how many times individual tigers are "recaptured" by the camera trap technique.
It is expected that the new software will allow researchers to rapidly identify animals, which in turn could speed up tiger conservation efforts.
"This new software will make it much easier for conservationists to identify individual tigers and estimate populations," said Ullas Karanth, Senior Conservation Scientist at the Wildlife Conservation Society and one of the study's co-authors. "The fundamentals of tiger conservation are knowing how many tigers live in a study area before you can start to measure success."
The study's authors found that the software, which can be downloaded for free at: www.conservationresearch.co.uk, was up to 95 percent accurate in matching tigers from scanned photos. Researches were also able to use the software to identify the origin of confiscated tiger skins based on solely on photos. Development of the software was funded through a Panthera project in collaboration with WCS.
Facilities for obtaining the images used for the construction of the three-dimensional surface model were provided by the Thrigby Hall Zoo, Norfolk, England. Centre for Wildlife Studies, Bangalore and the Wildlife Conservation Society, India Program provided images, local resources and staff time for this study, which was supported in part by a grant from the Liz Claiborne / Art Ortenberg Foundation.
Stephen Sautner | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
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23.07.2018 | Materials Sciences
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Make way for the fish! Scientists reared 111 walking fish on land to see how they would compare to fish raised in water.
The fish, a species called the Senegal bichir or "dinosaur fish," were selected as test subjects because of their walking ability; they have functional lungs and strong fins to pull them from one body of water to another. Scientists say this study will give us insight about the evolution of walking.
Fish raised out of the water walked better than those raised in water. They slipped less, raised their head higher and propelled themselves forward more effectively. Lead author Emily Standen called this a "more effective gait." Their skeletal structure also changed, making it easier for their heads and fins to move around.
"This is the first example we know of that demonstrates developmental plasticity may have facilitated a large-scale evolutionary transition," Hans Larsson of McGill University said in a press release.
In other words, being raised out of water changed some of the developmental features of the bichir, even though they were genetically similar to the fish raised in water. They changed their structure and behavior based on their environment - to an extent that scientists had never observed before. This discovery will help scientists understand how the first fish to walk out of water 400 million years ago eventually became tetrapods - four footed animals.
Apparently, fish don't need sunscreen, they need shoes. | <urn:uuid:2a19f78a-85bf-4003-bd59-f1f356081f65> | 4.0625 | 285 | News Article | Science & Tech. | 42.513197 | 95,566,784 |
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Video of the Month
Total online: 1
What is a Natural Sink?
The UNFCCC (United Nations Framework Convention on Climate Change) defines a sink as "any process, activity or mechanism which removes a grenhouse gas, an aerosol, or a precursor of a greenhouse gas from the atmosphere.
Our Natural Sinks
FORESTS - Through photosynthesis, plants absorb CO2 from the atmosphere, store the carbon in sugars, starch and cellulose and release the oxygen into the atmosphere.
OCEANS - Represent the largest active carbon sink on earth. This role is driven by two processes, the solubility pump (seawater and the thermohaline circulation and the biological processes that transport carbon (in organic and inorganic forms) from the surface to the ocean's interior. A small fraction of the organic carbon transported by the biological pump to the seafloor is buried in anoxic conditions under sediments and ultimately forms fossil fuels.
SOILS - Carbon as plant is sequestered in soils. Soils contain more carbon than is contained in vegetation and atmosphere combined. Grasslands contribute to soil organic matter. Much of this organic matter can remain unoxidized for long periods of time.
While not mandatory, the new UNFCCC reporting guidelines encourage Annex 1 parties to provide information on the following indirect GHGs
SOx - sulphur oxides
NOx - nitrogen oxides
CO - carbon monoxide
NMVOCs - non-methane volatile organic compound
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Four years after the Fukushima nuclear accident in Japan, viral photos of seemingly mutant flowers have reignited the debate over radiation levels.
@San_kaido described the abnormal growths: “The right one grew up, split into 2 stems to have 2 flowers connected each other, having 4 stems of flower tied belt-like. The left one has 4 stems grew up to be tied to each other and it had the ring-shaped flower. The atmospheric dose is 0.5 μSv/h at 1m above the ground.”
The Fukushima Daiichi plant was hit by a massive tsunami in 2011, leading to nuclear meltdown in three of the six reactors. So immediate reaction to the images was to either dismiss them as fakes or blame the lingering radiation.
“It’s likely to be just random mutation - we get lots of examples of fasciation sent to the RHS every year - but, of course, it’s not possible for us to say for certain if there is a link to radiation,” he said. “To be sure, one would have to examine the incidence in terms of numbers and area and any excess radiation present and do this over several years I suspect.”
So rest easy. Everything’s fine. Unless that’s just what our new flower overlords would want you to think. | <urn:uuid:47205998-0686-4058-8d2f-b63a2cf176ae> | 2.828125 | 282 | News Article | Science & Tech. | 62.165209 | 95,566,811 |
Reliability of underwater snorkel counts of adult Atlantic salmon, Salmo salar L., was analysed in the tributaries of the River Teno, close to the spawning period. In small (width 5-20 m) rivers, the replicated total counts of salmon were reasonably precise (CV = 5.4-8.5%), while in the medium-sized river (width 20-40 m) the precision of the counting method was considerably lower (CV = 15.3%). Low precision in a medium sized river was also observed in an experiment using marked live fish where the observation efficiency varied between 36.4% and 70.0%. In a small river, the detection efficiency of artificial fish silhouettes (test salmon) was almost perfect in pools (98%), but decreased in rapids (84%). Separate counts of males, females, grilse and large salmon were usually more variable than total counts, indicating that divers were more capable of locating a fish than properly identifying its sex and sea-age. The behaviour of adult salmon was favourable to conduct snorkel counts, as fish normally stayed still, or after hesitating, moved upstream (>95%of the cases) when encountering a diver. The high observation efficiency (>90%) and precision, favourable behaviour of salmon and congruence between snorkel counts and catch statistics in small rivers suggest that reliable data on Atlantic salmon spawning stock can be collected by snorkeling provided that the environmental conditions are suitable and the divers are experienced.
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+44 1803 865913
By: David Macdonald(Author), Rob Strachan(Author)
161 pages, colour & b/w photos, colour & b/w illustrations, b/w maps, tables
The Mink and the Water Vole reports the results of research that addressed the following questions:
1) What are the causes of the decline of the water vole?
2) What is the effect of American mink on our native fauna?
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One-dimensional artificial muscles like natural muscles have been studied for robots and artificial limbs to exoskeletons. Particularly, an artificial muscle using carbon nanotube (CNT) is very light and has excellent mechanical performance, and therefore CNT is researched as a promising material for artificial muscle.
Here, we demonstrated large tensile stroke of CNT based artificial muscle with graphene inside. Using biscrolling method shown in previous CNT hybrid yarn supercapacitors, electrochemical capacitance of artificial muscles could be increased by implanting graphene into CNT yarns. These graphene biscrolled CNT artificial muscles have slightly lower mechanical properties than bare CNT yarn artificial muscles, however it shows superior tensile stroke because of its large capacitance.
In addition to graphene, these artificial muscles have shown the possibility that other materials or strategies in reported supercapacitor studies can also be applied to improve the performance of electrochemical artificial muscles. Larger actuation of graphene biscrolled CNT artificial muscles could be applied to such areas as prosthetics devices.
Jae Sang Hyeon and Seon Jeong Kim, "Artificial muscle from graphene and carbon nanotube
(Conference Presentation)," Proc. SPIE 10594, Electroactive Polymer Actuators and Devices (EAPAD) XX, 105941F (Presented at SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring: March 08, 2018; Published: 27 March 2018); https://doi.org/10.1117/12.2296530.5758614577001.
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:e1e95bc0-65f9-4446-b369-77798a341e17> | 2.671875 | 402 | Academic Writing | Science & Tech. | 15.904413 | 95,566,835 |
By analyzing data on tree pollen extracted from ancient lake sediments, ecologists have sharpened the understanding of how forests can maintain a diversity of species. Their findings indicate that stabilizing processes have been more important than previously thought, and that the human-caused loss of species could upset that stability in ways that remain poorly understood.
"Quantifying the link between stability and diversity, and identifying the factors that promote species diversity, have challenged ecologists for decades," said Saran Twombly, program director in the National Science Foundation (NSF)’s division of environmental biology, which funded the research. "The contribution of this study is unique, as the scientists used a clever blend of long-term data and statistical modeling to test the opposing hypotheses of neutrality and stability as key factors promoting community assembly and diversity."
Scientist James Clark and graduate student Jason McLachlan of Duke University, published their findings in this week’s issue of the journal Nature.
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....
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:5804d7ea-294e-46cf-8f8f-9381934bbbb3> | 2.78125 | 793 | Content Listing | Science & Tech. | 32.961406 | 95,566,857 |
- DIVISION: Magnoliophyta (Flowering plants)
- CLASS: Magnoliopsida
- ORDER: Scrophulariales
- FAMILY: Scrophulariaceae (Figworts)
- GENUS: Mimulus
- SPECIES: 7
Named for blossoms that resemble a monkey's face sticking out its tongue, the monkey flower is one of the most colorful wildflowers.
This genus once contained more than 100 species. However, based on DNA studies, botanists restructured the group in 2012; today there are just seven species in the Mimulus genus, found in North America, Australia, Madagascar, Africa, and a handful of South Asian countries.
Monkey flower is a shrubby plant, reaching 2 to 3 feet (.6 to .9 meters) tall and wide. Pairs of sticky leaves sprout along unbranched stems that arch gracefully.
The 1.5-inch (3.8-centimeter) blossoms can range in color from white, yellow, and peach to rose, scarlet, and mahogany—some are streaked with more than one color. Flowers open in a sequence, starting with the lowest positioned and moving up the stems. The plant blooms for a long period—from spring into summer.
Mimulus are a colorful addition to the garden. Hummingbirds are drawn to the nectar, while ground squirrels, deer, and rabbits tend to leave them alone.
Monkey flower tolerates sun and partial shade, and are as striking in a pot as they are when planted in a drift, or large grouping. In mild climates, plants that are cut back after blooming in early June will reward the gardener with another wave of blossoms later in the summer. | <urn:uuid:81c0b712-eaec-4cff-8b37-e12b3d7e3290> | 3.28125 | 371 | Knowledge Article | Science & Tech. | 50.949241 | 95,566,860 |
Part of this YouTube video (see below, click to view)
pits DNA paleontolgist, Dr. Olaf Bininda-Emonds (U. Oldenburg), against bone trait paleontologist, Dr. John Wible (Carnegie Museum of Natural History) in their common and contrasting search for basal placental mammals. Both realize that DNA cladograms do not replicate bone cladograms and DNA cannot be utilized with ancient fossils.
Dr. Bininda-Emonds, used molecular clocks
in living taxa to hypothetically split marsupials from placentals about 160 mya ago (Late Jurassic).
By contrast, Dr. Wible reports (28:53),
“Our study supported the traditional view that there were no fossils living during the Cretaceous [that] were members of the placental group itself. There were only ancestors of the placentals living.” (unscripted verbatim)
The impulse for this argument
came from the discovery of Maelestes (Wible et al. 2007a,b; 28:30 on the video) from the Late Cretaceous (75 mya). Dr. Wible’s paper nested Maelestes with the pre-placental, Asiorcytes, another tree-shrew-like mammal from the Late Cretaceous. By contrast, the LRT, nests Maelestes unequivocally at the base of the tenrec/odontocete clade, well within the placental clade (Fig. 2), as we learned earlier here.
The large reptile tree
(subset in Fig. 2) nests the first known placental mammals at the 160 mya mark, matching the DNA predictions of Dr. Bininda-Emonds et al. A long list of taxa, including Maelestes, nest in the Jurassic and Cretaceous, contra Wible et al. Only more complete taxa are tested in the LRT and dental traits are not emphasized.
In the video Dr. Wible says, “Many modern groups, according to the molecular clock analysis, actually are, they should be, present in the Cretaceous fossil record. We can’t find them.” Actually Dr. Wible already found them, but does not recognize them for what they are. That’s a common problem in paleontology, largely due to taxon exclusion, that we’ve seen before here, here, here and here. And in dozens of other mislabeled clades, like multituberculates.
The Bininda-Edmonds et al. paper reports,
“Here we construct, date and analyse a species-level phylogeny of nearly all extant Mammalia to bring a new perspective to this question. Our analyses of how extant lineages accumulated through time show that net per-lineage diversification rates barely changed across the Cretaceous/Tertiary boundary. Instead, these rates spiked significantly with the origins of the currently recognized placental superorders and orders approximately 93 million years ago, before falling and remaining low until accelerating again throughout the Eocene and Oligocene epochs. Our results show that the phylogenetic ‘fuses’ leading to the explosion of extant placental orders are not only very much longer than suspected previously, but also challenge the hypothesis that the end-Cretaceous mass extinction event had a major, direct influence on the diversification of today’s mammals.”
The LRT agrees with the timing indicated by the DNA analysis
Placentals are indeed found in the LRT Cretaceous and Jurassic fossil record (Fig. 2). They were not recognized by traditional workers using smaller taxon lists, for what they were. The LRT minimizes taxon exclusion and so solves many paleo problems with an unbiased and wide gamut approach currently unmatched in the paleo literature. Extant birds have a similar deep time record based on a few recent finds.
there are currently large gaps spanning tens of millions of years, highlighting the rarity of fossil bearing locales. All Mesozoic mammals are rare.
The DNA tree
of the Bininda-Emonds team correctly splits monotremes from therians, but incorrectly nests ‘Afrotherians‘ with Xenarthrans at the base of all mammals followed by moles + shrews, bats + carnivores + hoofed mammals + whales, followed by primates and rodents. As anyone can see, this is a very mixed up order, placing small arboreal taxa in derived positions and stiff-backed elephants and in in basal nodes. This DNA analysis is not validated by the LRT.
To its credit, basal mammals in the LRT
greatly resemble their marsupial ancestors. Then derived mammals become generally larger, with derived tooth patterns, stiffer dorsal/lumbar areas and longer pregnancies with more developed (precocious) young.
Given three cladograms of placental relationships,
none of them identical, how does one choose which one is more accurate? Here’s my suggestion: look at each sister at each node and see where you best find a gradual accumulation of derived traits, without exception. And look at outgroups leading to basal members of the in group.
Some readers are still having a hard time realizing
that someone without direct access to fossils and without a PhD is able to recover a more highly resolved cladogram that features gradual changes between every set of sister taxa than trees published over the last ten years in the academic literature. I agree. This should not be taking place. This is not what I expected to find when I started this 7-year project. One tends to trust authority. It’s been an eye-opening journey. In nearly all tested studies overlooking relevant taxa continues to be the number one shortcoming. The LRT minimizes that issue. The number two problem is blind faith in DNA results. The number three problem is an apparent refusal to examine phylogenetic results to weed out mismatched recovered sister taxa.
The video spends also some time with Zhangheotherium,
which we looked at earlier here and here. The interviewed workers talk about the ankle spur, but as a venom injector, as in the duckbill, Ornithorhynchus, not as a membrane frame, like a calcar bone, as in bats.
The video considers Repenomamus a large Early Cretaceous mammal
but the LRT nests Repenomamus as a late-surviving synapsid pre-mammal, derived from a sister to Pachygenelus, as we learned earlier here.
PS. As touched on earlier,
many basal arboreal mammals were experimenting with gliding (e.g. Volaticotherium and Maiopatagaium), but only one clade, bats, experimented with flapping. This was, perhaps not coincidentally, during the Middle to Late Jurassic (Oxordian, 160 mya). Remember, these gliding membranes were all extensions of the infant nursery membrane found in colugos and other volatantians, not far from the basalmost placental, Monodelphis.
Bininda-Emonds ORP, et al., (9 co-authors) 2007. The delayed rise of present-day mammals. Nature 446(7135):507-512.
Wible JR, Rougier GW, Novacel MJ and Asher RJ 2007a. The eutherian mammal Maelestes gobiensis from the Late Cretaceous of Mongolia and the phylogeny of Cretaceous Eutheria. Bulletin of the American Museum of Natural History 327:1–123.
Wible JR, Rougier GW, Novacek MJ and Asher RJ 2007b. Cretaceous eutherians and Laurasian origin for placental mammals near the K/T boundary.” Nature, 447: 1003-1006. | <urn:uuid:f91c0b15-722a-4899-bc38-303c6693baed> | 3.046875 | 1,656 | Personal Blog | Science & Tech. | 42.931803 | 95,566,870 |
The history of oxygen is the history of life on Earth. For the first ~2 billion years of Earth's history, the atmosphere and oceans were largely devoid of free oxygen (O2). This changed ~2.4 billion year ago, when photosynethesis of primitive cyanobacteria caused the Great Oxidation Event (GOE). This event, the exact timing and tempo of which are still uncertain, marks one of the most profound changes our planet has ever undergone: persistent oxygenation of the oceans and atmosphere. However, the GOE does not represent the first incidence of free oxygen. Evidence for transient "whiffs" of oxygen prior to the GOE suggests the even more ancient occurrence of photosynethesis.
Our group is looking for evidence of the earliest “whiffs” of O2 to determine when photosynthesis began to oxygenate the environment. When did O2 first appear at Earth's surface? Once it was available, how stable was it in the atmosphere? What about in the oceans? We interrogate the history of oxygen on Earth using a variety of scientific methods, ranging from elemental and isotopic measurements in ancient sedimentary rocks, paleoredox proxies, experiments at extremely low levels of free oxygen, and modeling of the ancient Earth system.
Our interest in atmospheric oxygenation is not restricted to early-Earth, however, nor is it restricted to Earth's surface environment. We are also keenly interested in perturbations in atmospheric and oceanic oxygenation well after the GOE, as well as the role of the solid Earth in driving these changes over geologic time.
Our window onto early-Earth: ancient marine sedimentary rocks
Certain marine sedimentary rocks capture and preserve key chemical details of Earth's ancient oceans and atmosphere. For example, the abundance of redox-sensitive trace metals can provide invaluable information about changes in atmospheric and oceanic oxygenation. Our group uses drill cores from deep ocean sediments to assess elemental abundances through time.
Direct Clues: Isotopes
Some natural processes preferentially incorporate lighter or heavier elemental isotopes. This selective incorporation is called "fractionation," and evidence of it is sometimes preserved in the ancient rock record. If the process resulting in isotopic fractionation is linked to the availability of O2, the record of fractionation becomes a powerful tool in reconstructing Earth's oxygen history. The isotopic composition of marine sedimentary rocks can provide especially robust records of ancient conditions. To date, our group has developed and refined the use of Fe, Mo, Tl, and U isotopes as paleoredox proxies for perturbations in ancient Earth O2.
Indirect Clues: Experiments
Experiments under simulated early-earth conditions provide unrivaled information about how changes in the environment are reflected in the ancient rock record.
For example, experiments can be conducted under O2-deficient conditions to test the viability of alternate oxidation pathways, or to estimate the rate of elemental delivery to the ocean in a dominantly anoxic atmosphere.
Our analytical tool of choice: MC-ICPMS
We conduct isotope ratio measurements using a Thermo Neptune Multi-Collector Inductively Coupled Plasma Mass Spectrometer (MC-ICPMS). For details about our instrumentation, sample preparation, and analyses, please visit the website of the W. M. Keck Foundation Laboratory for Environmental Biogeochemistry (LINK).
Learn more about this research:
- Web site of the NSF “Dynamics of Earth Surface Oxygenation” project based at ASU (PI: Anbar)
- Web site of the Australian project of the Agouron Institute Drilling Program
- “A whiff of oxygen before the Great Oxidation Event?” Anbar et al., Science (2007)
- “Metal stable isotopes in paleooceanography” Anbar and Rouxel, Ann. Rev. Earth Planet. Sci. (2007)
- “Reconstructing paleoredox conditions through a multitracer approach: the key to the past is the present” Severmann and Anbar, Elements (2009)
- “Rapid expansion of oceanic anoxia immediately before the end-Permian mass extinction” Brennecka et al., Proc. Nation. Acad. Sci. (2011)
- Forbes interview about O2 and the NSF FESD project. | <urn:uuid:a419a06b-ba88-4aa2-ac4d-45b8f1854a0e> | 4.1875 | 912 | Knowledge Article | Science & Tech. | 23.52875 | 95,566,882 |
|Scientific Name:||Squalus raoulensis Duffy & Last, 2007|
|Taxonomic Source(s):||Eschmeyer, W.N., Fricke, R. and Van der Laan, R. (eds.). 2018. Catalog of Fishes: genera, species, references. Updated 29 March 2018. Available at: http://researcharchive.calacademy.org/research/ichthyology/catelog/fishcatmain.asp.|
|Taxonomic Notes:||The Kermadec Spiny Dogfish (Squalus raoulensis) is superficially very similar to the Northern Spiny Dogfish (S. griffini) but is a member of the S. megalops–cubensis species complex.|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Reviewer(s):||Ebert, D.A. & Kyne, P.M.|
The Kermadec Spiny Dogfish (Squalus raoulensis) occurs in isolated deepwater habitats in subtropical and possibly tropical regions of the Southwest Pacific remote from established deepwater fisheries. The steep, rocky nature of the Kermadec Ridge precludes bottom trawling over much of it and no commercially valuable mid-water trawl resources have been discovered on it. Bottom trawling is banned on the Kermadec and Colville Ridges until at least 2013. Given the low levels of historical fishing on the Kermadec Ridge, the abundance of this species is likely to be at or very close to unfished levels (although details of the exact population size of the species are unknown).
|Previously published Red List assessments:|
The Kermadec Spiny Dogfish is known from the Kermadec Islands (north of New Zealand) in the Southwest Pacific, specifically around Raoul Island, and south to at least Curtis and Chesseman Islands. However, this species is potentially widespread on oceanic ridges and seamounts in the Southwest Pacific.
This species is sympatric with the larger Northern Spiny Dogfish at Raoul Island. Bottom longline and dropline catch-effort data and submersible footage indicates that Squalus spp. (probably Northern Spiny Dogfish and Kermadec Spiny Dogfish) are abundant at upper slope depths around the Kermadec Islands (Beaumont et al. 2009).
Native:New Zealand (Kermadec Is.)
|FAO Marine Fishing Areas:|
Pacific – southwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||No data are available on population size, trends and structure of the Kermadec Spiny Dogfish. Given the low level of commercial fishing conducted on the Kermadec Ridge it is likely that abundance in the New Zealand region is at or close to unfished levels.|
|Current Population Trend:||Unknown|
|Habitat and Ecology:|
The habitat and ecology of the Kermadec Spiny Dogfish is poorly known. This is a small, demersal upper slope species, only known from oceanic ridges and seamounts in the subtropical Southwest Pacific. Specimens have been collected at 250–500 m, and it appears to be most abundant above 300 m depth. However, the full extent of the depth range is unknown. Males mature at 65.1 cm total length (TL). Female size at maturity unknown; female paratype was immature at 72.9 cm TL. Diet and reproductive biology are unknown.
|Use and Trade:||There is no known trade in the Kermadec Spiny Dogfish.|
At present the only potential anthropogenic threat to the Kermadec Spiny Dogfish is commercial fishing. However there is little or no commercial line fishing in demersal habitats on the Kermadec Ridge, and bottom trawling is banned on the Kermadec and Colville Ridges until at least 2013.
With the exception of the Kermadec Islands Marine Reserve, the entire Kermadec Arc system is subject to a number of mineral exploration licences, including oil and hydrothermal vent minerals. No mining is being undertaken in this area at present.
The Kermadec Arc has a large number of large, active submarine and subaerial volcanoes.
Bottom trawling is banned on the Kermadec and Colville Ridges until at least 2013, and part of the population of the Kermadec Spiny Dogfish is protected within a relatively large no-take marine protected area (Kermadec Islands Marine Reserve).
Collection of taxonomic material from suitable areas of habitat in the Southwest Pacific is required to determine the full distribution of this species. Research on all aspects of the species’ biology, particularly age and growth is required.
Beaumont, J., Rowden, A. A., Clark, M. R. 2009. Deepwater biodiversity of the Kermadec Islands Coastal Marine Area. NIWA Client Report. Prepared for the Department of Conservation. June 2009. 95 pp.
Duffy, C.A.J. and Last, P.R. 2007. Squalus raoulensis sp. nov., a new spurdog of the ‘megalops-cubensis group’ from the Kermadec Ridge. In: P.R Last, W.T. White and J.J. Pogonoski (eds), Descriptions of New Dogfishes of the genus Squalus (Squaloidea: Squalidae), CSIRO Marine and Atmospheric Research Paper No. 014. CSIRO, Australia.
IUCN. 2011. IUCN Red List of Threatened Species (ver. 2011.2). Available at: http://www.iucnredlist.org. (Accessed: 10 November 2011).
IUCN SSC Shark Specialist Group. Specialist Group website. Available at: http://www.iucnssg.org/.
|Citation:||Duffy, C.A.J. 2011. Squalus raoulensis. The IUCN Red List of Threatened Species 2011: e.T161469A5431296.Downloaded on 16 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:d70a6dad-20f0-4021-81a1-61f0a28245fe> | 2.609375 | 1,378 | Knowledge Article | Science & Tech. | 51.472259 | 95,566,890 |
Can the moon fit in a black hole?
heck ya the biggest one is large enough to swallow the one beside it
2 people found this useful
It cant and never will. The moon is just a big rock
It depends. First, we need to figure how to measure the size of ablack hole. For these purposes we will use the size event horizon.The problem is that size varies with the mas…s of the black hole.The smallest known black holes are about 3 times the mass of thesun with event horizons about 5 miles in radius, which gives avolume of about 520 cubic miles.The sun is about 460,000 miles inradius which gives a volume of about 4.1*10^17 (410 quadrillion)cubic miles. BY a simple volumetric ration you cold fit 780trillion such black holes into the sun. The problem here, is thatin such a circumstance the black holes would become a single blackhole of 2.3 quadrillion solar masses, with an event horizon about490 light years across. The largest known black hole is about 12 billion times the mass ofthe sun with an event horizon 44 billion miles across, far largerthan the sun and several times larger than the orbit of Pluto.
Although the gravitational pull near a black hole is so great that not even light can escape, the gravitational force scales with distance, so it is entirely possible that bla…ck holes have natural celestial bodies orbiting them. Please refer to the related link below.
No. The moon cannot become a black hole. A black hole is formed when a star 1 collapses in on itself. But not all collapsed stars become black holes either, in fact, only a s…mall percentage do. The majority of them become novas or supernovas. The moon is way too small and inactive (cold "dead" rock 2 ) to expand or contract as a star does so, no it cannot become a black hole by itself (it can be absorbed into one if one ever comes close enough.) 1 composed of hydrogen, helium, oxygen, nitrogen, and and carbon (nothing more complex) 2 composed of light rock - mostly the ores of orthopyroxene, clinopyroxene, and olivine, including ilmenite and ferrite (iron and titanium.)
yes and no depends on size of hole :]
It depends on where the black hole appeared, but irrespective of that bit of minutia, the same things would happen on the Earth as on the Moon if a black hole appeared somewhe…re, that being nothing with regards to a specific person.
No. The gravitational field of a black hole is so great that electromagnetic radiation in the visible spectrum does not escape from them. Therefore, you couldn't directly see …a black hole regardless of where you were in the universe.
There will not be a black hole in the moon today, tomorrow or forever (whenever that happens!)
The event horizon of any stellar mass black hole would be more thana mile across.
yes... it can because a black hole can even suck light in :) lol hope it helped.................................. c it can suck in nearley everything
Yes, everything can be sucked in to a black hole, even light
No - Since all matter in the galaxy revolves about the black hole, there is no individual satellite (or moon) for which the black hole is primary. Note: A natural satellite…, or moon, is a celestial body that orbits a planet or smaller body, which is called its primary.
One might quickly conclude that black holes don't belong on HRdiagrams since the latter is designed for stars, and black holesgenerally aren't considered stars. Further, given… that a spectraltype would be necessary to plot any given entity on an HR diagram,a black hole would have to have such typification, which it doesnot have - given that, due to relativistic effects, it emits nosignificant light. If it were assigned a spectral type, it wouldstill need to have an agreed-upon absolute magnitude, which somemight argue was "infinite" for the same reason - reflecting theobserver's inability to detect any (intrinsic) light. It is,however, generally accepted that black holes emit a kind ofblack-body radiation owing to quantum effects (Hawking radiation)for a temperature that may vary with its surface gravity. Even if aconsensus could be built regarding its luminosity and its spectraltype, its presence on an HR diagram may not be 'useful,' despiteits significance in theories of stellar evolution to which the HRdiagram so abundantly contributes. | <urn:uuid:74bfb88f-5778-4590-94bd-bd88d7a87055> | 3.703125 | 958 | Q&A Forum | Science & Tech. | 56.836 | 95,566,902 |
Growth and Survival of Genetically-Modified Pseudomonas Putida in Soils of Different Texture
Given current concerns about the risks associated with the use of genetically-modified organisms (GEMMO) in open ecosystems it is important to be able to determine reliably the survival of such organisms and how this survival is influenced by primary environmental factors.
KeywordsClay Soil Open Ecosystem Pseudomonas Putida Peat Soil Current Concern
Unable to display preview. Download preview PDF. | <urn:uuid:07561e97-4180-4ae6-b760-886d35bfbbbe> | 2.515625 | 104 | Truncated | Science & Tech. | 5.05 | 95,566,907 |
Phospholipid Headgroups as Sensors of Electric Charge
In 1839 the anatomist T. Schwann published his “Microscopic Investigations on the Similiarity of Structure and Growth of Animals and Plants” in which he provided the first evidence that animals and plants are composed of the same elements, the cells. The new cell theory immediately led to the question of how the cells could manage to move matter from one cell to the other. Around 1900 the biologist E. Overton investigated the transport rate of more than 300 different organic compounds in animal and plant cells. He observed that all compounds which were easily soluble in oil or similar solvents could move through the living protoplast with high speed whereas other compounds which were easily soluble in water but not in ether, alcohol, or oil migrated only slowly. Based on this selective solubility of plant and animal cells he concluded that the outer surface of the cell was impregnated by a substance which had solubility properties similar to those of a fatty oil. In particular, he suggested that the outer cell layer was composed of a mixture of lecithin and cholesterol 1.
KeywordsMembrane Surface Biological Membrane Quadrupole Splitting Dipole Field Electric Surface Charge
Unable to display preview. Download preview PDF.
- 1.E. Overton, Vierteljahresschr. Naturforsch. Ges. Zürich XLIV, 88 (1899).Google Scholar
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Researchers have shown that it is possible to train artificial neural networks directly on an optical chip. The significant breakthrough demonstrates that an optical circuit can perform a critical function of an electronics-based artificial neural network and could lead to less expensive, faster and more energy efficient ways to perform complex tasks such as speech or image recognition.
Posted on 19 July 2018 | 2:30 pm
A newly developed analysis method can detect hydroxyl radicals (OH) with unprecedented sensitivity. Because OH is a critical component in the combustion processes that power most vehicles, the new approach could advance the development of novel types of engines and fuels that would be more efficient and environmentally friendly.
Posted on 19 July 2018 | 11:23 am
Electron microscopy has allowed scientists to see individual atoms, but even at that resolution not everything is clear.
Posted on 19 July 2018 | 9:40 am
Researchers from the University of North Carolina at Chapel Hill have reached a new milestone on the way to optical computing, or the use of light instead of electricity for computing. They explored a new way to select and send light of a specific color using long silicon wires that are several hundred nanometers in diameter (about 1,000 times smaller than a human hair) and their work enabled a new type of nanoscale "light switch" that can turn on and off the transmission of one color of light over very long distances.
Posted on 17 July 2018 | 4:13 pm
The interaction of traveling waves in dissipative systems, physical systems driven by energy dissipation, can yield unexpected and sometimes chaotic results. These waves, known as dissipative pulses (DSs), are driving experimental studies in a variety of areas that involve matter and energy flows.
Posted on 17 July 2018 | 3:00 pm
A plan to incorporate a third bent waveguide into a silicon-based light splitter led A*STAR researchers to develop a device capable of a 30-fold improvement in splitting efficiency. The novel on-chip light splitter marks a major breakthrough in improving high-performance data transmission systems, as well as applications in quantum computing.
Posted on 16 July 2018 | 12:40 pm
Researchers at the Technion-Israel Institute of Technology have constructed a first-of-its-kind optic isolator based on resonance of light waves on a rapidly rotating glass sphere. This is the first photonic device in which light advancing in opposite directions moves at different speeds.
Posted on 13 July 2018 | 11:53 am
There is no denying that people today are dependent on their phone and other gadgets. When something goes wrong with your phone or your laptop it becomes very difficult for you to manage your daily routine because you are almost dependent on your device for every little thing. Whether it means calling up a near ...
Posted on 12 July 2018 | 2:28 pm
If you want to get the greatest benefit from a beam of light—whether to detect a distant planet or remedy an aberration in the human eye—you need to be able to measure its beam front information.
Posted on 11 July 2018 | 7:33 pm
Terahertz radiation can be used for a wide variety of applications and is used today for airport security checks just as much as it is for material analysis in the lab. The wavelength of this radiation is in the millimetre range, meaning that it is significantly larger than the wavelength of visible light. It also requires specialised techniques to manipulate the beams and get them into the right shape. At TU Wien, shaping terahertz beams is now something of a resounding success: with the help of a precisely calculated plastic screen produced on the 3-D printer, terahertz beams can be shaped as desired.
Posted on 11 July 2018 | 1:00 pm
Mobile games have evolved over the years. Pokémon Go which is a recently launched games has already crossed millions of downloads across the world and is the new craze for everyone. Pokemon-go-hack.de is one of the web links which will give you some smart cheat code to help to go faster and further into the ...
Posted on 11 July 2018 | 12:43 pm
All of you have seen and used a printer and a computer. If you ever paid proper attention then you will see that there are a lot of drivers that are needed to use the printer in the right command. It is really very important that the command given by the computer to the printer ...
Posted on 11 July 2018 | 11:40 am
Technology created by researchers at the Okinawa Institute of Science and Technology Graduate University (OIST) is literally shedding light on some of the smallest particles to detect their presence – and it's made from tiny glass bubbles.
Posted on 11 July 2018 | 10:24 am
Based at the National Research Nuclear University MEPhI (Russia), a research team led by Prof. Yuri Rakovich has developed a tunable micro-resonator for hybrid energy states between light and matter using light to control the chemical and biological properties of molecules. The results have been published in the Review of Scientific Instruments.
Posted on 10 July 2018 | 10:15 am
Fluorescence-based biosensing and bioimaging technologies are widely used in research and clinical settings to detect and image various biological species of interest. While fluorescence-based detection and imaging techniques are convenient to use, they suffer from poor sensitivity. For example, when a patient carries low levels of antigens in the blood or urine, the fluorescent signal can be feeble, making visualization and diagnosis difficult. For this reason, fluorescence-based detection is not always preferred when sensitivity is a key requirement.
Posted on 9 July 2018 | 8:18 pm
A KAIST research group presented photonic capsules for injectable laser resonators using microfluidic technology. The capsule's diameter is comparable to a human hair and stable in gas and liquid media, so it is injectable into any target volume. The research group, headed by Professor Shin-Hyun Kim in the Department of Chemical and Biomolecular Engineering, applied an interesting optical property from nature.
Posted on 9 July 2018 | 1:20 pm
Cockroaches can be a menace. They are one of the most irritating pests one can have in their houses and to get rid of them is also always a task. Insect repellent is said to be the best roach killer available in the market. No matter how bad is the cockroach infestation in your house, ...
Posted on 8 July 2018 | 2:13 pm
T-shirts come in various colors, designs and patterns. Family shirts are most wanted these days. These t-shirts can never go out of style. They look unique and fashionable. T-shirts can be worn by everybody irrespective of age, sex and gender. It is the most comfortable wear. It can be worn as casual with shorts and ...
Posted on 8 July 2018 | 1:26 pm
When we get into age adolescent we are actually productive and we have no idea how to take our energy and help the body grow. Doing exercise is the ultimate way to help the body to help the body to get full great things about the adolescent age group. This is actually the age which ...
Posted on 7 July 2018 | 1:22 pm
Nowadays the trend of online dating is increasing at a really great rate. Along with this, there is gay dating app that people can use if they are gay to find their right partner. If you remembered some time ago, there was no respect for gays in the society but as the society is developing ...
Posted on 7 July 2018 | 10:59 am
Researchers from Chalmers University of Technology, Sweden, and Tallinn University of Technology, Estonia, have demonstrated a 4000 kilometre fibre-optical transmission link using ultra low-noise, phase-sensitive optical amplifiers. This is a reach improvement of almost six times what is possible when using conventional optical amplifiers. The results are published in Nature Communications.
Posted on 5 July 2018 | 10:47 am
Ever wondered where parrots get their bright plumage? An Otago-led project may have just solved the mystery.
Posted on 5 July 2018 | 9:10 am
So you have decided to join the blogging bandwagon? Congratulations on completing your initial steps and setting up your blog. Before getting too far ahead of yourself, pause and take a deep breath. There are still a lot of things that can go wrong and we will show you exactly how to avoid them. While ...
Posted on 4 July 2018 | 12:53 pm
While ultrasound is one of the most common medical imaging tools, conventional electronic ultrasound devices tend to be bulky and cannot be used at the same time as some other imaging technologies. A new ultrasound system that uses optical, instead of electronic components, could improve performance while giving doctors significantly more flexibility in how they use ultrasound to diagnose and treat medical problems.
Posted on 2 July 2018 | 5:06 pm
In Norse mythology, the Bifrost was the rainbow bridge linking the realm of the gods to Earth. At UC Santa Barbara, it is also the name of the Broadly-tunable Illumination Facility for Research, Outreach, Scholarship, and Training (BIFROST), a laser facility that will provide coherent light throughout the visible and infrared spectrum to 10 laboratories in the campus's Broida Hall, which houses the Department of Physics.
Posted on 2 July 2018 | 4:33 pm
Electronic circuits are miniaturized to such an extent that quantum mechanical effects become noticeable. Using photoelectron spectrometers, solid-state physicists and material developers can discover more about such electron-based processes. Fraunhofer researchers have helped revolutionize this technology with a new spectrometer that works in the megahertz range.
Posted on 2 July 2018 | 12:25 pm
Nowadays, Gift cards are playing an important role, and you can get great benefits with the help of Gift Cards. There is some Gift Card Rebel that is just as simple as a Gift card generator to use. This is just the same, and you can get to use some free gift cards from many ...
Posted on 2 July 2018 | 10:02 am
Every year, we give out gift to friends and family on numerous occasions from birthdays to Christmas and anytime we feel like they need a bit of cheering up. Of course with the passing years, it has become increasingly difficult to think of a new gift. When all else fail, we highly suggest turning to ...
Posted on 1 July 2018 | 7:06 pm
Researchers and engineers have long sought ways to conceal objects by manipulating how light interacts with them. A new study offers the first demonstration of invisibility cloaking based on the manipulation of the frequency (color) of light waves as they pass through an object, a fundamentally new approach that overcomes critical shortcomings of existing cloaking technologies.
Posted on 28 June 2018 | 3:30 pm
Scientists have discovered a new property of wave propagation that leads to a new way to improve the resolution of virtually all optical technologies, including microscope lenses, telecommunications, laser-based lithography, biological and astronomical imaging. All these systems transmit information and energy through wave propagation. Researchers at the Institute for Basic Science have discovered that if light passes through asymmetric apertures, astigmatism arises and can degrade image resolution. Having identified this previously unsuspected problem, the researchers showed how to remedy it.
Posted on 28 June 2018 | 1:21 pm
A multicolor laser pointer you can use to change the color of the laser with a button click—similar to a multicolor ballpoint pen—is one step closer to reality thanks to a new tiny synthetic material made at Sandia National Laboratories.
Posted on 28 June 2018 | 1:17 pm
Tiny, nano-sized crystals of salt encoded with data using light from a laser could be the next data storage technology of choice, following research by Australian scientists.
Posted on 28 June 2018 | 11:25 am
Just like merry people at a party, photons perform random walks through white paint; but their density remained out of control. Recently, scientists at the University of Twente in the Netherlands have managed to control the photon energy density inside opaque materials such as white paint.
Posted on 28 June 2018 | 11:16 am
Okayama University researchers describe in the journal Optics Express the use of Terahertz (THz) chemical microscopy to measure the pH of water-based solutions with a volume as small as 16 nL. The findings are important to be able to measure pH concentrations in small-volume solutions for clinical and environmental analyses.
Posted on 28 June 2018 | 11:16 am
Speed limits apply not only to traffic. There are limitations on the control of light as well, in optical switches for internet traffic, for example. Physicists at Chalmers University of Technology now understand why it is not possible to increase the speed beyond a certain limit—and know the circumstances in which it is best to opt for a different route.
Posted on 28 June 2018 | 6:43 am
A team headed by the TUM physicists Alexander Holleitner and Reinhard Kienberger has succeeded for the first time in generating ultrashort electric pulses on a chip using metal antennas only a few nanometers in size, then running the signals a few millimeters above the surface and reading them in again a controlled manner. The technology enables the development of new, powerful terahertz components.
Posted on 27 June 2018 | 11:05 am
Researchers have scaled up a powerful fluorescence imaging technique used to study biological processes on the cellular level. Previously limited to samples just millimeters in area, the expanded approach can analyze samples with areas up to 4 square centimeters. With further development the new approach could find use in the clinic as a sensitive and precise method for identifying the edges of tumors during surgery.
Posted on 26 June 2018 | 5:03 pm
In the photoelectric effect, a photon ejects an electron from a material. Researchers at ETH have now used attosecond laser pulses to measure the time evolution of this effect in molecules. From their results they can deduce the exact location of a photoionization event.
Posted on 22 June 2018 | 11:40 am
Modern microscopy has given scientists a front-row seat to living, breathing biology in all its technicolor glory. But access to the best technologies can be spotty.
Posted on 21 June 2018 | 4:22 pm
A new microscope system can image living tissue in real time and in molecular detail, without any chemicals or dyes, report researchers at the University of Illinois.
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We quantified sedimentation of organic carbon in 12 Swedish small boreal lakes (< 0.48 km(2)), which ranged in dissolved organic carbon (DOC) from 4.4 to 21.4 mg C l(-1). Stable isotope analysis suggests that most of the settling organic matter is of allochthonous origin. Annual sedimentation of allochthonous matter per m(2) lake area was correlated to DOC concentration in the water (R-2 = 0.41), and the relationship was improved when sedimentation data were normalized to water depth (R-2 = 0.58). The net efflux of C as CO2 from the water to the atmosphere was likewise correlated to DOC concentration (R-2 = 0.52). The losses of organic carbon from the water column via mineralization to CO2 and via sedimentation were approximately of equal importance throughout the year. Our results imply that DOC is a precursor of the settling matter, resulting in an important pathway in the carbon cycle of boreal lakes. Thus, flocculation of DOC of terrestrial origin and subsequent sedimentation could lead to carbon sequestration by burial in lake sediments.
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In a new Collaborative Research Centre scientists from Würzburg and Jena are examining the function of membrane receptors with the most modern light microscopy. The objective is to gain new findings about how these receptors work and to develop the high-performance light microscopy further.
Membrane receptors are participating as important switching molecules in almost all biological processes. These commonly complex proteins are located in the outer cell boundaries, the cell membranes, just like very sensitive antenna and are waiting for signals in the form of small molecules, so called ligands which can attach themselves specifically and custom-fit to the respective receptors.
The receptor then changes its chemical form and therefore its properties and thus gives the starting signal for other signal or material transports in the cell. Membrane receptors are, for example, the docking stations for adrenaline and growth hormones, for nicotine and opiates.
The new Collaborative Research Centre
These receptors are the focus of a “ReceptorLight” Collaborative Research Centre, newly set up by the German Research Foundation, where scientists from Jena and Würzburg are participating. Spokesperson is Professor Markus Sauer, physiologist from the Jena University Clinic; representative spokesperson is Professor Markus Sauer, head of the department for Biotechnology and Biophysics at University of Würzburg. The scientists want to continue to decode the switching plans of different membrane receptors in 22 sub-projects and with an entire arsenal of microscopic technologies. Depending on the question, they will also work on the further development of methods and the evaluation of the images gained.
Technology made in Würzburg
One of the methods used, is the one developed by Professor Markus Sauer, the dSTORM technology that allows an extremely precise statement regarding the location and number of molecules through light-induced control of the fluorescence properties of pigments and the stochastic evaluation of many individual molecular images.
“In order to display the spatial distribution of more than ten different target molecules in an experiment, we need a multi-level marking, detection and bleaching process that we want to extend to different colouring agents.” This is how the physical chemist from the biocenter of the University of Würzburg describes the program of the project that he is developing together with professor Rainer Heintzmann from the Leibniz Institute of Photonic Technologies and from the Institute of Physical Chemistry in Jena.
Light as a physical tool
Over the last years, new light-microscopic methods have contributed to a better understanding of the way membrane receptors work. “One main advantage of light as a physical tool lies in the comparatively small interruption of biological processes and structures”, emphasizes Professor Klaus Benndorf. “This enabled substantial new findings on the speed of attachment but also on the localisation of the receptors, partly with a spatial resolution in the range of 20 nanometres, i.e. far below the optical resolution limit, Benndorf added.
Molecular mechanisms of encephalitis
In a project that is also at home at the two sites of the SFB, the neurologist from Jena, Professor Christian Geis and the biophysicist PD Dr. Sören Doose examine the molecular mechanisms of an encephalitis, where patients form autoantibodies against a glutamate receptor in the cell membrane of neurons. From electrophysiological measurements, two-photon fluorescence microscopy and high-resolution imaging of these receptors, such as dSTORM, the scientists are expecting insights on the basic principles of neurological autoimmune diseases with resolutions that have so far not been achieved in space or time.
Würzburg plant scientists also take part
And plant cell receptors are also in the focus of scientists: Würzburg plant scientists professor Rainer Hedrich and Professor Dietmar Geiger are researching the switching behaviour of receptors of the dry stress hormone which regulates the stomata, by means of high-resolution fluorescence microscopy and fluorescence resonance energy transfer.
The receptor light study groups in Würzburg and Jena are combining their diverse methodical skills in the area of high-performance light microscopy with insights of physiology and biophysics of very different membrane receptors. In the process, they will not only jointly use highly modern light-microscopic methods but also special algorithms in order to analyse image data and an independent research and image data management which are each established in autonomous sub-projects. “We want to better understand the way membrane receptors work and at the same time we want drive the option of light-microscopic imaging forward - in spatial as well as in temporal resolution, and also in the complexity of the biological systems viewed, says Klaus Benndorf.
Prof. Dr. Klaus Benndorf, Institute for Physiology II, Jena University Clinic
T: +49 (0)3641 934350, Klaus.Benndorf@med.uni-jena.de
Prof. Dr. Markus Sauer, Biocenter, University of Würzburg
T: +49 (0)931 31-88687, email@example.com
Robert Emmerich | Julius-Maximilians-Universität Würzburg
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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