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Our recent progress in the fabrication of FeSe and KxFe2−ySe2 ultra thin films and the understanding of their superconductivity properties is reviewed. The growth of high-quality FeSe and KxFe2−ySe2 films is achieved in a well controlled manner by molecular beam epitaxy. The high-quality stoichiometric and superconducting crystalline thin films allow us to investigate the intrinsic superconductivity properties and the interplay between the superconductivity and the film thickness, the local structure, the substrate, and magnetism. In situ low-temperature scanning tunneling spectra reveal the nodes and the twofold symmetry in FeSe, high-temperature superconductivity at the FeSe/SrTiO3 interface, phase separation and magnetic order in KxFe2−ySe2, and the suppression of superconductivity by twin boundaries and Fe vacancies. Our findings not only provide fundamental information for understanding the mechanism of unconventional superconductivity, but also demonstrate a powerful way of engineering superconductors and raising the transition temperature.
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Presentation on theme: "6.02 ChemLive Exothermic and Exothermic Reactions"— Presentation transcript:
1 6.02 ChemLive Exothermic and Exothermic Reactions
2 Chemical bonds are formed during exothermic reactions. Exothermic chemical reactions cause their surroundings to warm up by giving off heat.Chemical bonds are formed during exothermic reactions.Exothermic reactions are usually spontaneous.This is a reaction that takes place on its own without an external force and another reaction needed to drive it.Example: Lighting a match. When the head of the match is struck, it results in the spontaneous release of stored energy (heat) from the reactants into the surroundings.
3 Potential Energy Diagram-Exothermic The reactants contain more stored energy than the product because energy from external sources is not required, but given off. This gives the product more stability due to the lower amount of energy needed.
4 Endothermic Reactions Energy is drawn in from the external environment, causing its surroundings to loose heat, or "cool down."Chemical bonds are broken with endothermic reactions.Most endothermic reactions are not spontaneous.A non spontaneous reaction is a reaction that doesn't occur naturally and it normally tends to favor the reactants of a chemical reaction.Example: Photosynthesissunlight + 6CO2(g) + H2O(l) = C6H12O6(aq) + 6O2(g)
5 Potential Energy Diagram- Endothermic The endothermic chemical reaction creates a product that has a higher energy level than the original materials, causing the reactant's stored energy to decrease.
6 Exothermic/Endothermic Examples Exothermic ReactionsEndothermic Reactionsrusting ironcooking an eggcondensation of rain from water vaporevaporation of waterformation of snow in cloudsconversion of frost to water vapormaking ice cubesmelting ice cubesburning sugarproducing sugar by photosynthesis
7 Measuring HeatreactionExothermic reaction, heat given off & temperature of water risesreactionEndothermic reaction, heat taken in & temperature of water drops
8 6.02 Endothermic and Exothermic lab activity Hands-on Assignment ChoicesChoice One: Steel Wool and VinegarChoice Two: Baking Soda and Vinegar
9 Choice One: Steel Wool and Vinegar Materials:one piece of steel woolvinegarthermometer (if you have one)glass jar with lid, or disposable plastic cup (not polystyrene—also referred to as Styrofoam™) with lid/plastic wrapnewspaper (Use it to cover the countertop next to the kitchen sink. This could get a little messy!)
10 Choice One: Steel Wool and Vinegar Procedure:Place the steel wool in a jar or cup and cover with vinegar.Let the steel wool soak in the vinegar for one minute.If you have a thermometer, measure the temperature of the vinegar and steel wool.Squeeze the vinegar out of the steel wool and pour the vinegar from the jar into the sink.Place the steel wool immediately back into the jar/cup and seal the lid. You should be able to see it start rusting over the next few minutes.Place your hands on the outside of the container after sealing the lid and record any temperature change that you observe.When you think the temperature change is complete, open the jar. If you have a thermometer, measure the temperature of the steel wool.When you are done making observations, it is safe to dispose of the steel wool in the trash. Be sure to wash the glass jar and thermometer before putting them away.
11 Choice One: Steel Wool and Vinegar Observations to help you with your 6.02 quiz that follows the activity:1.What was the initial temperature in the jar______ degrees Celsius.2.What was the temperature after the reaction? _____degrees Celsius.3.What was the change in temperature? Increase or decrease?4.Based on information from Part I and from observations, was this reaction Exothermic or Endothermic?An increase would be exothermic. A decrease would be endothermic5.Are chemical bonds forming or breaking? Observation- What do you see happening?6.In this experiment, the acidic vinegar dissolved a protective coating off the steel wool, allowing the oxidation of the steel to begin. This process is called rusting. In this reaction, iron (III) is combined with oxygen gas to form iron oxide.Write the balanced chemical reaction for the rusting of iron. __Fe+__O2 __FeO3
12 Choice Two: Baking Soda and Vinegar Materials:one disposable plastic (not polystyrene—also referred to as Styrofoam™) cupone disposable plastic spoon (plastic fork or knife may be used)thermometer (if you have one)measuring cup and spoonnewspaper (Use it to cover the countertop next to the kitchen sink. This could get a little messy!)baking sodavinegar
13 Choice Two: Baking Soda and Vinegar ProcedureMeasure two tablespoons of baking soda and pour it into the clean, dry plastic cup.Measure out one cup of vinegar.If you have a thermometer, place it in the measuring cup of liquid and write down the initial temperature.Grasping the plastic cup near the bottom with one hand, pour the liquid into the plastic cup with your other hand.Continue to grasp the cup as you stir the solution gently with the plastic spoon. Observe any temperature change felt through the plastic cup.If you have a thermometer, record the temperature change as you stir the solution very gently.When you are done making observations, it is safe to pour the solution down the sink and to dispose of the plastic cup and spoon in the trash. Be sure to wash the measuring spoon, measuring cup, and thermometer before putting them away.
14 Choice Two: Baking Soda and Vinegar Observations to help you with your 6.02 quiz that follows the activity: 1.What was the initial temperature in the jar of vinegar?______ degrees Celsius. 2.What was the temperature after the reaction with baking soda? _____degrees Celsius. 3.What was the change in temperature? Increase or decrease? 4.Based on information from Part I and from observations, was this reaction Exothermic or Endothermic? An increase would be exothermic. A decrease would be endothermic 5.Are chemical bonds forming or breaking? Observation- What do you see happening? 6.In this experiment, the acidic vinegar reacted with baking soda producing sodium acetate and carbonic acid. The carbonic acid quickly decomposes into carbon dioxide and water. The chemical reactions involved: HC2H3O2 + NaHCO3 ===> NaC2H3O2 + H2CO3 H2CO3 ---> H2O + CO2 | <urn:uuid:f309dd6e-7d3d-4dab-b8af-188eb04581a5> | 4.25 | 1,438 | Tutorial | Science & Tech. | 43.552561 | 95,522,719 |
Aerosol Detection - Total Operational Weather Readiness - Satellites (TOWR-S)
VIIRS Aerosol Detection
Frequently Asked Questions about the VIIRS Aerosol Detection Product
1) What is this product?
This product outputs six different possibilites of aerosol or no aerosol in the atmosphere. The various possible categories are volcanic ash, clouds, dust, smoke, none/unknown/clear, and snow/ice. This product is useful not only to identify the presence of aerosols in the atmosphere, but also in identifying the type of aerosol, especially differentiating between smoke and dust. This information can assist with forecasting dust storms and issuing dust storm warnings, identifying the movement of volcanic ash, recognizing smoke from fires that may not yet be large enough for the VIIRS Active Fires Product to detect, and being aware of decreased air quality.
2) How often do I receive this data?
The S-NPP satellite is part of the Afternoon Train (A-Train) of satellites. It crosses the equator at ~1:30am and ~1:30pm local time every day. However, this product is only produced during daytime hours.
3) How do I display this product in AWIPS-II?
4) How do I interpret the color maps associated with this product?
5) What should I use in conjunction with this product to produce a better forecast?
Geostationary satellite imagery, including the GOES-R Aerosol Detection product. Also, the VIIRS Aerosol Optical Depth Product.
6) How is this product created?
Image based aerosol detection always involves assumptions of the radiometric characteristics of aerosol, clear and cloudy scenes. The surface conditions also influence the separation of aerosol pixels from those with clear-sky or cloud. The product algorithm currently uses spectral and spatial tests to identify pixels with smoke or dust in the daytime. The algorithm also treats the detection differently for water and land. 1
Techniques for the remote sensing of aerosols using solar and thermal measurements from satellites have been developed for several instruments, including AVHRR and MODIS. Fundamentally, these methods are based on the radiative signatures of aerosols. The problem of accurate detection and classification is compounded by the fact that the physical characteristics of aerosols (e.g. particle size distribution, concentration, chemical composition, location in the atmosphere) change as the aerosol layer develops and dissipates. These physical changes are capable of affecting the radiative characteristics of the original aerosol and our capability to detect them from satellite observations. In addition to being present at the source region, aerosols are transported by winds to other regions of the globe.1
1NOAA/NESDIS/STAR. NOAA NESDIS Center for Satellite Applications and Research Algorithm Theoretical Basis Document: JPSS Suspened Matter (Aerosol Detection) Product. v1.0, December 9 2015. | <urn:uuid:d37a4f6c-31d2-4296-9475-d32d77260b8d> | 2.90625 | 612 | FAQ | Science & Tech. | 31.431483 | 95,522,721 |
This species is known from the Upper Amazon Basin of southern Colombia (Leticia), Ecuador, Peru, and western Brazil (Acre and Rondonia). It might be present in Bolivia, but requires confirmation. Its elevation is from 100-800 m asl.
Habitat and Ecology
Its habitat is both secondary and primary tropical moist forest. At Santa Cecilia, Ecuador, all individuals were found at night on vegetation. Males usually call from emergent swamp vegetation, or, less frequently, at the edge of forest (Duellman 1978). Eggs are deposited on leaves over waterbodies; larvae develop in these waters.
This is an uncommon species.
There are no major threats; it is a widespread species with large areas of suitable habitat remaining. There is some localized habitat loss to general human activities such as agriculture (crops, livestock etc.).
In Ecuador, its geographic range overlaps with Reserva Biológica Limoncocha, Yasuni National Park and Cuyabeno Reserva de Producción Faunística. Possibly occurs in Parque Nacional Natural Amacayacu, Colombia. It is uncertain if it is present in a reserved zone within Peru.
Red List Status
Least Concern (LC)
Listed as Least Concern in view of its wide distribution, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category.
This species was previously within the genus Hyla but has recently been moved to the resurrected genus Dendropsophus (Faivovich, et al., 2005).
Coloma, L.A., Ron, S.R., Castro, F., Rueda-Almonacid, J.V., Bolívar, W., Hoogmoed, M., Angulo, A., Icochea M., J. & Azevedo-Ramos, C. 2004. Dendropsophus bokermanni. The IUCN Red List of Threatened Species 2004: e.T55419A86439862. http://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T55419A11306193.en | <urn:uuid:ca5f7be4-7f52-4444-9510-180dda684cde> | 2.625 | 469 | Knowledge Article | Science & Tech. | 49.995726 | 95,522,750 |
Authors: George Rajna
NIMS and Tohoku University have jointly observed an anisotropic magneto-Peltier effect—a thermoelectric conversion phenomenon in which simple redirection of a charge current in a magnetic material induces heating and cooling. Recently, researchers from the China University of Mining and Technology have theoretically exposed the fundamental aspects of this thermal transport along double-stranded DNA (dsDNA) molecules. This "robot," made of a single strand of DNA, can autonomously "walk" around a surface, pick up certain molecules and drop them off in designated locations. The world of nanosensors may be physically small, but the demand is large and growing, with little sign of slowing. In a joint research project, scientists from the Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy (MBI), the Technische Universität Berlin (TU) and the University of Rostock have managed for the first time to image free nanoparticles in a laboratory experiment using a highintensity laser source. For the first time, researchers have built a nanolaser that uses only a single molecular layer, placed on a thin silicon beam, which operates at room temperature. A team of engineers at Caltech has discovered how to use computer-chip manufacturing technologies to create the kind of reflective materials that make safety vests, running shoes, and road signs appear shiny in the dark. In the September 23th issue of the Physical Review Letters, Prof. Julien Laurat and his team at Pierre and Marie Curie University in Paris (Laboratoire Kastler Brossel-LKB) report that they have realized an efficient mirror consisting of only 2000 atoms. Physicists at MIT have now cooled a gas of potassium atoms to several nanokelvins—just a hair above absolute zero—and trapped the atoms within a two-dimensional sheet of an optical lattice created by crisscrossing lasers. Using a high-resolution microscope, the researchers took images of the cooled atoms residing in the lattice. Researchers have created quantum states of light whose noise level has been " squeezed " to a record low. An elliptical light beam in a nonlinear optical medium pumped by " twisted light " can rotate like an electron around a magnetic field.
Comments: 39 Pages.
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Articles by Murray K. Gingras in JoVE
Determination of the Settling Rate of Clay/Cyanobacterial Floccules Tiffany Playter1, Kurt Konhauser1, George W. Owttrim2, Denise S. Whitford2, Tyler Warchola1, Cheryl Hodgson1,3, Aleksandra M. Mloszewska4, Bruce Sutherland1, J.-P. Zonneveld1, S. George Pemberton1, Murray K. Gingras1 1Department of Earth and Atmospheric Sciences, University of Alberta, 2Department of Biological Sciences, University of Alberta, 3Department of Earth Sciences, Simon Fraser University, 4Earth Sciences Department, University of Toronto The interaction and sedimentation of the clay and bacterial cells within the marine realm, observed in natural environments, can be best investigated in a controlled lab environment. Here, we describe a detailed protocol, which outlines a novel method for measuring the sedimentation rate of clay and cyanobacterial floccules.
Other articles by Murray K. Gingras on PubMed
Bilaterian Burrows and Grazing Behavior at >585 Million Years Ago Science (New York, N.Y.). | Pubmed ID: 22745427 Based on molecular clocks and biomarker studies, it is possible that bilaterian life emerged early in the Ediacaran, but at present, no fossils or trace fossils from this time have been reported. Here we report the discovery of the oldest bilaterian burrows in shallow-water glaciomarine sediments from the Tacuarí Formation, Uruguay. Uranium-lead dating of zircons in cross-cutting granite dykes constrains the age of these burrows to be at least 585 million years old. Their features indicate infaunal grazing activity by early eumetazoans. Active backfill within the burrow, an ability to wander upward and downward to exploit shallowly situated sedimentary laminae, and sinuous meandering suggest advanced behavioral adaptations. These findings unite the paleontological and molecular data pertaining to the evolution of bilaterians, and link bilaterian origins to the environmental changes that took place during the Neoproterozoic glaciations.
Response to Comment on "Bilaterian Burrows and Grazing Behavior at >585 Million Years Ago" Science (New York, N.Y.). | Pubmed ID: 23430639 Gaucher et al. suggest that their field observations and petrographic analysis of one thin section do not support an Ediacaran age for the trace fossils-bearing strata of the Tacuarí Formation. We have strengthened our conclusion of an Ediacaran age for the Tacuarí Formation based on reassessment of new and previously presented field and petrographic evidence. | <urn:uuid:6af35877-7699-4174-9b70-c3f565625193> | 2.65625 | 573 | Content Listing | Science & Tech. | 25.471989 | 95,522,777 |
Friday morning at 5:24 am (0924 GMT), a rocket owned by the US company SpaceX will blast off from Florida carrying two and a half tons of gear from NASA, only to dock three days later and 250 miles (400 kilometers) above Earth at the International Space Station.
The rocket itself is not new. It launched a NASA satellite into orbit two months ago, then landed back on Earth — upright — on a barge in the Atlantic Ocean off Cape Canaveral.
Even the Dragon capsule, carrying the cargo and affixed to the top of the rocket was used before, having flown a mission to the ISS in 2016.
Friday's flight will be the 15th SpaceX mission for the US space agency since 2012, one of which exploded in flight. Another company, Orbital ATK, has completed nine supply trips, with one explosion as well.
These missions may appear routine, but they represent a revolution in space travel. Before SpaceX, only national governments resupplied the space station.
Today, NASA is so dependent on the private sector that the US space agency has signed contracts with SpaceX and Boeing to send astronauts to space beginning next year, as soon as their capsules are ready.
NASA has been unable to send people to space since the space shuttle programme ended in 2011. Instead, the world's space agencies buy seats aboard Russia's Soyuz spaceships, which launch from Baikonur, Kazakhstan.
"The combination of government and private sector activity is unrivaled," said John Logsdon, professor emeritus of political science and international affairs at George Washington University.
SpaceX, founded by Tesla CEO and space enthusiast Elon Musk, has shaken up the satellite launch sector, with more than 55 launches of its Falcon 9 rocket since 2010.
Thanks to SpaceX, the United States has taken the global lead in launches once again, after losing ground for more than a decade to Russia and China, which launched even more rockets.
"The Russians have certainly been one of the countries that have had the greatest loss in terms of launch market share," said Tom Stroup, president of the Satellite Industry Association.
The number of satellite launches is expected to surge in the coming years.
Never before has low-Earth orbit been so accessible.
Miniature satellites weighing a few pounds (kilograms) can be made quickly and launched for tens of thousands of dollars.
These CubeSats make up 292 of the 345 satellites launched in 2017, according to the Satellite Industry Association.
"They are almost disposable," said Claude Rousseau of Northern Sky Research, explaining that their operational life expectancy is about seven years and they can be easily replaced.
In the coming months, SpaceX and the startup OneWeb want to send into orbit constellations of hundreds of small satellites that will provide internet access.
Competition in fierce in the Earth observation market, with multiple companies at work on constellations to offer military or civilian clients high resolution imagery of infrastructure, farming areas and military installations.
To meet the demands on the small satellite market, companies are working on smaller rockets.
One, made by the US venture Rocket Lab, is to try its first launch from New Zealand on Wednesday.
China and India, whose space programmes are mainly backed by public funds, also aim to boost market share.
China has already launched more rockets this year than it did in all of 2017, according to Northern Sky Research.
Tourism, Moon and Mars
The age of space tourism is also approaching.
Virgin Galactic is ramping up tests for its piloted SpaceShipTwo VSS Unity, which is launched from an airplane. A seat will cost $2,50,000.
And Blue Origin, founded by Amazon CEO Jeff Bezos, will sell tickets next year for a seat on its New Shepard spacecraft, which is designed to carry six people to space.
These two vehicles will not go into orbit around Earth, but will allow passengers to experience spaceflight and weightlessness for several minutes before returning to Earth.
Finally, NASA is working on a space station that would orbit the Moon, as a stepping off point for missions to Mars in the coming decades.
NASA is building the Orion capsule and Space Launch System (SLS) rocket to send people around the Moon for the first time since 1972. The SLS will be the most powerful rocket ever built by the United States. Its first lunar orbit mission is planned for 2020, with astronauts on board by 2023. | <urn:uuid:cf6d1c4e-efe6-4eeb-8d38-8b24141037b1> | 3.046875 | 907 | News Article | Science & Tech. | 45.327703 | 95,522,791 |
In the 1980s, some astronomers started batting around the idea that the sun had a long-lost twin, circling undetected in the edges of the solar system. They suggested that the existence of a companion star to our own might explain some cataclysmic events on Earth, like the mass extinction of the dinosaurs. Perhaps the orbit of this star, they said, was capable of disrupting the Oort cloud, a massive region of icy objects beyond Neptune’s orbit. Its gravitational forces could dislodge comets and send them hurtling toward Earth. The astronomers named the hypothetical star Nemesis, after the Greek goddess of retribution.
Today, the theory of Nemesis, of an evil twin lurking in the night sky and messing with comets, has fallen out of circulation. The companion star has never been found. But that doesn’t mean it never existed.
Most sun-like stars in the universe—stars with masses similar to our own—exist in pairs. Astronomers don’t yet understand exactly how these pairs, known as binaries, form. But as they dig deeper into the mysteries of star formation, they’re finding some clues. The latest is a new study of a distant cluster of young stars in the Milky Way that suggests nearly all sun-like stars are born in pairs, bolstering the claim that our sun has a twin.
A pair of researchers from the Harvard’s Smithsonian Astrophysical Observatory and the University of California, Berkeley, used radio telescope observations to study the distribution and orientation of stars in Perseus, a massive, very cold gas-filled cloud located about 600 light-years from Earth. Perseus is home to dozens of sun-like stars less than a million years old, the baby versions of our 4.5 billion-year-old yellow orb in the sky. Using statistical models, the researchers turned back the clock and investigated how the star population within the cloud unfolded over time. They found that in order to explain what they were seeing, they had to assume that the stars inside Perseus first formed and lived in binaries, before other forces may have started pushing them around.
So, yes, the sun may have had a twin, in the very beginning—but not for long.
To understand why, let’s look at Perseus. Perseus, like other similar clouds, is home to the birthplace of stars: egg-shaped cocoons of molecular gas, known as dense cores. The researchers observed several kinds of systems across Perseus. There are wide binaries, which contain two young stars orbiting each other, separated by more than 500 astronomical units, or AU. (One AU is the average distance between the sun and Earth, about 93 million miles). These young stars appear to be aligned with the long axis of a dense core, which suggests they may have formed together. There are tight binaries, containing slightly older stars orbiting less than 500 astronomical units apart and showing no alignment to dense cores. And there are single-star systems, like our sun.
The researchers, based on their simulations, determined that all the stars started off as wide binaries, aligned with their egg-shaped cocoons. About 60 percent of the pairs split up a few million years later, flying apart. The rest spiraled closer together, forming tight binaries.
If our sun had a twin, it would have orbited at least 17 times farther from the sun than Neptune. After a few million years together, it drifted away for good, into interstellar space, mingling with the other stars of the Milky Way.
“We don’t know exactly how we lost it,” said Steven Stahler, a theoretical physicist at the University of California, Berkeley, and one of the researchers. Stahler said friction between the young stars and surrounding gas can cause them to shrink their orbits, moving closer and closer together. Mergers are rare, since young stars emit winds powerful enough to drive off clouds of gas and reduce friction. But the reasons for breaking apart remain more of a mystery. One star may be ejected from its dense core, or the core itself could splinter, leaving two halves with two stars to float apart.
Younger stars are trickier to observe than their older counterparts, thanks to their dusty, dense cores, which block out their light, said Sarah Sadavoy, the lead author and an astronomer at the Smithsonian Astrophysical Observatory at Harvard. But clusters of young stars are the best places to investigate the mysteries of star formation, she said.“There’s been less time for things to get disrupted,” she said.
Perseus is just one cloud in the cosmos, of course. Despite its location, the makeup of the cluster may not be universal. “All of the observations that are being conducted always give only a little snapshot of some phase in the process, and every observation that is being taken gives a different picture,” said Anna Frebel, an MIT astrophysicist who studies the early stars of the universe, and who was not involved in the study. “Today, 13 billion years later, the universe is a lot more complicated, and every different gas cloud where you might have stars has undergone its very specific, billion-year evolution.”
So, is there any hope of finding a sibling to our sun? Astronomers could study their velocity and motions and then work backwards, spinning time in reverse to see whether one once had the same origin. Or they could examine the absorption spectra of stars, to figure out their chemical composition. If astronomers spot a star whose composition matches that of our sun, they can speculate they both came from the same cloud billions of years ago.
But these searches only work well if the star recently moved away from the solar system. Billions of years have passed. Nemesis is probably thousands of light-years away. It could even be on the opposite side of the center of the galaxy.
“Ultimately, there’s no way to track this down,” Sadavoy said. “It’s lost in the cosmos at this point.”
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Discussion of all aspects of cellular structure, physiology and communication.
Poison wrote:Someone correct me if I'm wrong but as much as I know not all organelles replicate themselves. The ones which have its own genetic material can replicate. For example: mitochondria, chloroplasts, centrioles, ribosomes.
The other ones are sythesized before the division starts. For example; lysosomes.
huh? wait a sec, please answer this question as i need to do a presentation on centrioles on monday:
do centrioles have their own dna? and if they don't, is there an actual scientific explanation as to how they are able to self replicate?
I thought they didn't have their own DNA, and that there are no proved explanation...can any clarification be offered to me?
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We use computer simulations to study highly dense systems of granular particles that are driven by oscillating forces. We implement different dissipation mechanisms that are used to extract the injected energy. In particular, the action of a simple local Stokes' drag is compared with non-linear and history-dependent frictional forces that act either between particle pairs or between particles and an external container wall. The Stokes' drag leads to particle motion that is periodic with the driving force, even at high densities around close packing where particles undergo frequent collisions. With the introduction of inter-particle frictional forces this "interacting absorbing state" is destroyed and particles start to diffuse around. By reducing the density of the material we go through another transition to a "non-interacting" absorbing state, where particles independently follow the force-induced oscillations without collisions. In the system with particle-wall frictional interactions this transition has signs of a discontinuous phase transition. It is accompanied by a diverging relaxation time, but not by a vanishing order parameter, which rather jumps to zero at the transition.
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Choose a citation style from the tabs below | <urn:uuid:70b8fda1-ed39-47c5-8c74-00f178193e9b> | 2.96875 | 239 | Academic Writing | Science & Tech. | 15.497452 | 95,522,834 |
The normal distribution has several characteristics that make it the underlying foundation of much of inferential statistical tools. List these characteristics and explain how they contribute to the power of the distribution as foundation of inferential decision making.© BrainMass Inc. brainmass.com July 15, 2018, 3:48 pm ad1c9bdddf
In probability theory and statistics, the normal distribution or Gaussian distribution is a continuous probability distribution that describes data that cluster around a mean or average. The graph of the associated probability density function is bell-shaped, with a peak at the mean, and is known as the Gaussian function or bell curve.
Characteristics of Normal Distribution
1. The family of normal distributions is closed under linear transformations. That is, if X is normally distributed with mean μ and variance σ2, then a linear transform aX + b (for some real numbers a ≠ 0 and b) is also normally distributed.
2. Also if X1, X2 are two independent normal random variables, with means μ1, μ2 and standard deviations σ1, σ2, then their linear combination will also be normally distributed.
3. The converse of (1) is also true: if X1 and X2 are independent and their sum X1 + X2 is distributed normally, then both X1 and X2 ...
Why is the normal distribution important and why is it so commonly used? | <urn:uuid:4674f8e0-18c0-4241-a178-338a46e291cc> | 4.03125 | 297 | Truncated | Science & Tech. | 52.32897 | 95,522,841 |
Not only do off-shore wind turbines not harm marine life, but they actively encourage more of it, a very encouraging study has just concluded, after closely following the effects of the off-shore wind farms being built off the European coast.
A Swedish Scientist at the Stockholm University’s Zoology Department studying the effects of off-shore wind turbines discovered that marine life has become more abundant and diverse near the foundations. Dan Wilhelmsson found that offshore wind turbines constitute habitats for fish, crabs, mussels, lobsters and plants.
The seabed in the vicinity of the wind turbines had higher densities of fish compared to further away from the turbines and in control areas. This was despite that the natural bottoms were rich in boulders and algae. Blue mussels dominated on the wind turbines that appeared to offer good growth conditions.
“Hard surfaces are often hard currency in the ocean, and these foundations can function as artificial reefs. Rock boulders are often placed around the structures to prevent erosion (scouring) around these, and this strengthens the reef function,” says Dan Wilhelmsson.
Not only were the foundations giving a boost to marine life, but interestingly, we might be able to build-in features to them in such a way as to enhance conditions to favor those species that need more protection.
“With wind and wave energy farms, it should be possible to create large areas with biologically productive reef structures, which would moreover be protected from bottom trawling. By carefully designing the foundations it would be possible to favor and protect important species, or, conversely, to reduce the reef effects in order minimize the impact on an area,” says Dan Wilhelmsson.
Come to think of it, this shouldn’t come as such a surprise. There are many instances of sunken boats, planes and other metal and concrete objects having been thoroughly repurposed by the creatures of the deep for their own needs. We already use artificial reefs to rebuild populations of marine life. | <urn:uuid:51e54ce4-1f63-40bd-af5a-752fc888e4ed> | 3.546875 | 409 | News Article | Science & Tech. | 33.950542 | 95,522,851 |
Comets | Facts About The Solar System’s Icy Wanderers ☄
Snowballs With Long Hair!
Comets are small objects made up of rock and ice with highly elliptical orbits that on approaching the Sun, heat up and release gases and debris forming a tail of dust and gas! The huge coma and tail, which is blown by the Sun’s solar winds, is what we can sometimes see from Earth and that which has been recorded for millennia by ancient civilizations. Comets are classified broadly as short-period and long-period comets that likely originate in either the Kuiper belt or Oort Cloud beyond.
A Short History Of Comets
Throughout history ancient cultures such as the Chinese, Greeks, Babylonians, Indian and medieval Europeans kept extensive records of comets passages through the skies. They had little understanding of their true nature, both in awe and often frightened by their appearance; seeing them as a bad omen.
Future orbital studies based on these accounts began to reveal that comets were simply far flung frozen worlds orbiting the Sun. Edmond Halley famously predicted in 1705 that the comets of 1531, 1607 and 1682 weren’t different comets, but the same one, and successfully predicted its return in 1758!
How Does A Comet Get Its Name?
Throughout history comets were simply named after their discoverer or if they’re particularly bright (i.e. considered a ‘Great Comet’) it was often referred to as ‘The Great Comet of…’ and the year of its appearance.
With improved technology, many fainter comets started being discovered, so the International Astronomical Union decided to formalize the naming process. Nowadays, once a comet is discovered, and its orbit determined, it’s official name begins with the code defining whether the orbit is either periodic (P/) or non-periodic (C/), followed by the year of discovery, followed by a code for the time of year and order of discovery in that period. If the comet is periodic it has a number in front of the ‘P/’ representing what number periodic comet it is e.g. Halley’s Comet was famously the first periodic comet so has the code 1P/Halley.
A few other examples of famous comets and their full names are as follows; Comet Hale-Bopp (C/1995 O1), Comet Shoemaker-Levy 9 (D/1993 F2) and Comet Tempel 1 (9P/Tempel). Since spacecraft discover many of the comets nowadays, you’ll often see comets named with SOHO or WISE representing which spacecraft discovered them.
Types And Origins Of Comets
Comets are essentially small icy Solar System bodies that are left over from the formation of the Solar System and likely originate in the dark frozen regions of the outer Solar System known as the Kuiper belt, Scattered Disc and Oort Cloud.
Following being perturbed by the gravity of a larger passing object they are flung towards the Sun where their volatile ices sublimate forming the often brilliantly bright coma and gas/dust tails. Depending on the comets orbit, they’ll fall into one of two main categories – Short (orbits of 200 years or less) or Long period comets (orbits potentially several million year long).
What Is A Comet Made Of?
A comet is like a small dark and dirty snowball that heats up as it leaves the deep freeze of space and approaches the Sun. When it heats up near the inner Solar System it develops the following structure;
- A small nucleus of solid rock, dust and ices which is between a few hundred meters to ten’s of kilometers wide.
- A large coma forms (maybe several times the size of Earth) which is a loosely bound atmosphere of gases that are boiling off the comets nucleus.
- Most noticeable is the dramatic dust tail which curls away from the comet as the suns solar winds (and light pressure) pushes the tiny dust particles away from the Sun.
- There is often a second fainter gas tail which is straighter as this is composed of lighter gases again pushed away from the Sun by the solar winds.
The particles which stream off a comet during its close approach to the Sun are left in space. If the Earth’s passes through the debris cloud those particles enter our atmosphere and appear as annual meteor showers!
Spacecraft Visits To Comets
Scientists waited until 1986 to get their first close up look at a comet when a small armada of spacecraft made observations of Halley’s Comet. Deep Impact’s visit to Tempel 1 yielded significant information after an impactor deliberately struck the comet at 10.2 km/s and the Stardust probe even returned samples of a comets dust tail to Earth from its flyby of Comet Wild 2. The most comprehensive study of a comet came with ESA’s Rosetta spacecraft which orbited the nucleus and even managed to land its probe Philae on the Comet Churyumov-Gerasimenko in 2014 – the first landing on a comet ever! | <urn:uuid:9c2c4f9d-3c15-4c3c-9a5b-33c382eb6202> | 4.09375 | 1,076 | Knowledge Article | Science & Tech. | 46.814575 | 95,522,869 |
Taiga Biome (Coniferous Forest Biome, Boreal Biome)
The taiga biome is the largest terrestrial biome on earth. The only biome larger than the taiga biome is the ocean biome. It spans across many continents including North America, Europe, and Asia. The reason for this is because these three continents used to be connected by the Bering Land Bridge.
The taiga biome is sometimes called the coniferous forest biome because of all the coniferous trees. Sometimes it is called the boreal forest biome because it is located in the norther part of the earth.
Climate and Weather in the Taiga Biome
The climate in the taiga biome changes quickly with the seasons. In the summer it gets very warm and in the winter it gets very, VERY cold! Temperatures in the winter can reach -60 degrees Fahrenheit. In fact, it remains below freezing for about 6 months each year!
Plants in the Taiga Biome
The taiga biome is home to 29% of all the of earth’s forests. These forests contain many types of trees but mainly pine, spruce, and fir trees. Most of the trees are evergreens which mean that these trees keep their leaves year-round. Because these trees do not drop their leaves, the soil doesn’t receive many nutrients. So, few plants or vegetation grows on the ground.
Trees are the main ingredient for making paper. Because the taiga biome has a lot of trees, people commonly log this area. However, trees are a valuable resource that takes a long time to regrow. If humans cut down too many trees, the taiga biome will become bare. If it becomes to bare, many animals will have to find a new home which can be very hard to do.
Animals in the Taiga Biome
Many animals exist is this biome but have had to adapt to survive. For example, hares (wild rabbits), change their fur color from brown/gray in the summer to pure white in the winter. They do this so they can blend into the snow. Other animals that are common in this biome are moose, wolves, and otters. Also there are millions of birds and insects that live in this biome. During the long winter months, animals hibernate or migrate to warmer climates.
Other Fun Facts About This Biome
During the hot summer season, fires commonly occur in this biome. Fires were once thought of as bad natural disasters. But we have recently learned that fires are important for this biome to survive. Fires clear out old dead trees, providing nutrients to the soil and allowing new trees to grow. | <urn:uuid:a5e37d3f-9e1d-441d-ba67-a9f02d5d1186> | 3.9375 | 547 | Knowledge Article | Science & Tech. | 58.038891 | 95,522,872 |
Bengaluru: Around the same time as Cyclone Pam flattened the tiny Pacific island nation of Vanuatu early this month, untimely rains and hailstorms lashed Maharashtra in India destroying at least 5.5 million hectares of winter crops.
That was a big jolt to the nation still recovering from the worst calamity of its kind in Uttarakhand in June 2013 when thousands perished in flooding and landslides induced by heavy rains and, in September 2014, from the flash floods in Srinagar, the deadliest to hit the valley in 60 years.
The list of extreme weather events that crippled life in India in recent times gets longer when one includes the July 26, 2005, downpour -- the heaviest in recorded history -- that flooded the entire city of Mumbai and the August 6, 2010, cloudburst in Leh that dumped 14 inches of rain in two hours.
It was not just the extreme rain events that have surprised weathermen. The longest heat wave that swept northern India in June 2014 drove Delhi's temperature to 47.6 degrees Celsius, the hottest in 62 years.
According to Global Climate Risk Index, published by Germanwatch, India is one of the three countries (besides the Philippines and Cambodia) affected by the most extreme weather events in 2013.
The Intergovernmental Panel on Climate Change (IPCC) has predicted that "rainfall patterns in peninsular India will become more and more erratic, with a possible decrease in overall rainfall, but an increase in extreme weather events".
Indian climatologists agree.
"There has been a 50 percent increase in extreme rainfall events during the past 50 years in India," Jayaraman Srinivasan, chairman of the Divecha Centre for Climate Change in Bengaluru, wrote in the journal Current Science after the Uttarakhand disaster.
"During the past few months there have been a few unusual weather events but there is no clear indication that these are related to global warming," Srinivasan told IANS.
"I would argue that earth's weather and climate are governed by non-linear processes, and hence one should expect unusual weather events now and then."
He, however, added that "extreme rainfall events will increase as global warming proceeds unabated, and hence it is absolutely essential for us to be prepared to tackle more extreme rainfall events in the future".
Bhupendra Nath Goswami, former director of the Indian Institute of Tropical Meteorology (IITM) in Pune, says his studies have shown that the occurrence of "extreme rainfall events" had been increasing over the country in the last five-six decades.
"We can say with a high degree of confidence that this increasing trend is due to global warming," Goswami told IANS.
Global warming, Goswami said, "increases the moisture holding capacity of the atmosphere and makes it more convectively unstable, facilitating a stronger rain event.
"Because the atmosphere has become more unstable over the whole country, one or more such events can occur anywhere at a given time."
Goswami said that all climate models predict an increasing trend of these extreme events into the future.
Therefore, "there is strong reason to prepare ourselves to face the potential disasters associated with increasing frequency and intensity of these events".
"This erratic behaviour is a regional manifestation of climate change," says R. Krishnan, a senior scientist at IITM, who has made a detailed analysis of long-term climate data sets.
"Our findings show that the pronounced surface warming of the Tibetan Plateau has altered the spatial distribution of atmospheric temperature, strengthened the sub-tropical westerly winds over the region and created favourable conditions for increased variability of the Western Disturbances activity," Krishnan told IANS.
Western disturbance is a low pressure system that originates over the Mediterranean sea and moves eastwards, bringing winter rain and snow to the north-western parts of the Indian subcontinent.
Some British scientists suggest a possible link between the extreme events in mid-latitudes and rapid loss of the ice cap that covers the Arctic Ocean.
How will the extreme rainfall events impact Indian agriculture?
According to Minister of State for Agriculture Sanjeev Balyan, an analysis by the Indian Council of Agricultural Research has revealed that nearly 81.3 million hectares of area spread over 122 districts in 11 states may suffer from extreme weather events.
He recently told parliament a study predicted an 18 percent reduction in crop yields for maize and six percent for wheat and rice by 2020.
The impact on agriculture in the Ganges river basin -- the largest food producing region in India -- may be particularly pronounced according to a report in the journal Climatic Change by scientists of the Indian Institute of Technology in Kharagpur.
On the basis of Regional Climate Model simulations they predict that the Gangetic basin may face an increasing incidence of "precipitation extremes" during summer months in future. Crop productivity of wheat is expected to reduce, they report.
Another Global Climate Model simulation study by researchers at the CSIR-Fourth Paradigm Institute in Bengaluru shows "intensification of extreme rainfall over most parts of India by the end of the century".
According to their report in Current Science, the increase in temperature, coupled with a decline in rainfall in the west coast, will have drastic consequences on the production of crops.
"Over other regions, increases in heavy precipitation can increase surface run-off and lead to intense floods and landslides." | <urn:uuid:566a4ef7-354d-47a2-9ede-195dc0ea5072> | 3 | 1,122 | News Article | Science & Tech. | 28.219846 | 95,522,884 |
The Belleplaine test site, located in the island of Guadeloupe (French Lesser Antilles) includes a three-accelerometer vertical array, designed for liquefac- tion studies. The seismic response of the soil column at the test site is computed using three methods: the spectral ratio method using the vertical array data, a numerical method using the geotechnical properties of the soil column, and an operative fre- quency domain decomposition (FDD) modal analysis method. The Belleplaine test site is characterized by a mangrove layer overlaid by a stiff sandy deposit. This con- figuration is widely found at the border coast of the Caribbean region, which is exposed to high seismic hazard. We show that the buried mangrove layer plays the role of an isolation system equivalent to those usually employed in earthquake engineering aimed at reducing the seismic shear forces by reducing the internal stress within the structure. In our case, the flexibility of the mangrove layer reduces the distortion and the stress in the sandy upper layer, and consequently reduces the potential of liquefaction of the site. | <urn:uuid:1cdbe5d3-dbea-47cf-a056-0b6e4383960f> | 2.578125 | 228 | Academic Writing | Science & Tech. | 18.182833 | 95,522,885 |
Immediate Consequences of Galactic Cosmic Ray Observations
Summarizing the observational material on galactic cosmic rays presented in the last three chapters we note that the solar system is bombarded by cosmic rays from all sides isotropically. The chemical and isotopic composition of the nucleonic component is similar to that of solar flare particles; all nucleons exhibit power law energy spectra over a wide range of kinetic energies. Cosmic ray electrons exhibit a break in their power law energy spectrum at about 20 GeV with spectral index ≃ 2.2 below the break energy and ≃ 3.2 above the break energy.
KeywordsNeutron Star Interstellar Medium Mass Loss Rate Supernova Explosion Total Power Input
Unable to display preview. Download preview PDF. | <urn:uuid:5d9fd103-a993-4f47-8745-463f1dfbfc59> | 2.890625 | 153 | Truncated | Science & Tech. | 29.12839 | 95,522,891 |
Paleontologists have documented the evolutionary adaptations necessary for ancient lobe-finned fish to transform pectoral fins used underwater into strong, bony structures, such as those of Tiktaalik roseae. This enabled these emerging tetrapods, animals with limbs, to crawl in shallow water or on land.
But evolutionary biologists have wondered why the modern structure called the autopod—comprising wrists and fingers or ankles and toes—has no obvious morphological counterpart in the fins of living fishes.
In the Dec. 22, 2014, issue of the Proceedings of the National Academy of Sciences, researchers argue previous efforts to connect fin and fingers fell short because they focused on the wrong fish. Instead, they found the rudimentary genetic machinery for mammalian autopod assembly in a non-model fish, the spotted gar, whose genome was recently sequenced.
“Fossils show that the wrist and digits clearly have an aquatic origin,” said Neil Shubin, PhD, the Robert R. Bensley Professor of organismal biology and anatomy at the University of Chicago and a leader of the team that discovered Tiktaalik in 2004. “But fins and limbs have different purposes. They have evolved in different directions since they diverged. We wanted to explore, and better understand, their connections by adding genetic and molecular data to what we already know from the fossil record.”
Initial attempts to confirm the link based on shape comparisons of fin and limb bones were unsuccessful. The autopod differs from most fins. The wrist is composed of a series of small nodular bones, followed by longer thin bones that make up the digits. The bones of living fish fins look much different, with a set of longer bones ending in small circular bones called radials.
The primary genes that shape the bones, known as the HoxD and HoxA clusters, also differ. The researchers first tested the ability of genetic “switches” that control HoxD and HoxA genes from teleosts—bony, ray-finned fish—to shape the limbs of developing transgenic mice. The fish control switches, however, did not trigger any activity in the autopod.
Teleost fish—a vast group that includes almost all of the world’s important sport and commercial fish—are widely studied. But the researchers began to realize they were not the ideal comparison for studies of how ancient genes were regulated. When they searched for wrist and digit-building genetic switches, they found “a lack of sequence conservation” in teleost species.
They traced the problem to a radical change in the genetics of teleost fish. More than 300 million years ago, after the fish-like creatures that would become tetrapods split off from other bony fish, a common ancestor of the teleost lineage went through a whole-genome duplication (WGD)—a phenomenon that has occurred multiple times in evolution.
By doubling the entire genetic repertoire of teleost fish, this WGD provided them with enormous diversification potential. This may have helped teleosts to adapt, over time, to a variety of environments worldwide. In the process, “the genetic switches that control autopod-building genes were able to drift and shuffle, allowing them to change some of their function, as well as making them harder to identify in comparisons to other animals, such as mice,” said Andrew Gehrke, a graduate student in the Shubin lab and lead author of the study.
Not all bony fishes went through the whole genome duplication, however. The spotted gar, a primitive freshwater fish native to North America, split off from teleost fishes before the WGD.
When the research team compared Hox gene switches from the spotted gar with tetrapods, they found “an unprecedented and previously undescribed level of deep conservation of the vertebrate autopod regulatory apparatus.” This suggests, they note, a high degree of similarity between “distal radials of bony fish and the autopod of tetrapods.”
They tested this by inserting gar gene switches related to fin development into developing mice. This evoked patterns of activity that were “nearly indistinguishable,” the authors note, from those driven by the mouse genome.
“Overall,” the researchers conclude, “our results provide regulatory support for an ancient origin of the ‘late’ phase of Hox expression that is responsible for building the autopod.”
This study was supported by the Brinson Foundation; the National Science Foundation; the Brazilian National Council for Scientific and Technological Development grants; the National
Institutes of Health; the Volkswagen Foundation, Germany; the Alexander von Humboldt-Foundation, the Spanish and Andalusian governments; and Proyecto de Excelencia.
Additional authors include Mayuri Chandran and Tetsuya Nakamura from the University of Chicago; Igor Schneider from the Instituto de Ciencias Biologicas, Universida de Federal do Para, Belem, Brazil; Elisa de la Calle-Mustienes, Juan J. Tena, Carlos Gomez-Marin and José Luis Gómez-Skarmeta from the Centro Andaluz de Biología del Desarrollo, Sevilla, Spain; and Ingo Braasch and John H. Postlethwait from the Institute of Neuroscience, University of Oregon.
Sr Science Writer
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NRL Reveals New Meteorological Insight into Mid-Level CloudsBy Daniel Parry | July 21, 2014
Research meteorologists at the U.S. Naval Research Laboratory (NRL) Marine Meteorology Division (MMD) and Scripps Institution of Oceanography, employing the Navy's Mid-Course Doppler Radar (MCR) at Cape Canaveral, were able to characterize mid-level, mixed-phase altocumulus clouds.Research meteorologists at the U.S. Naval Research Laboratory (NRL) Marine Meteorology Division (MMD) and Scripps Institution of Oceanography, employing the Navy's Mid-Course Doppler Radar (MCR) at Cape Canaveral, were able to characterize mid-level, mixed phase altocumulus clouds in unprecedented detail. The plot depicts the MCR-derived vertical velocity with the solid red and blue contours bounding upward and downward motion, respectively. The white curves depict the cloud layer position and the dashed blue line the peak cloud top radiative cooling. The black arrows depict cloud circulation features. The radiation-induced subsidence is shown by the horizontally oriented ellipses near cloud-top.
(U.S. Naval Research Laboratory)
In altocumulus clouds, at medium altitudes ranging from 6,000 feet to 20,000 feet above mean sea level, water droplets can remain in a supercooled liquid phase at temperatures below zero degrees Celsius, the freezing point of water. The supercooled liquid water found at temperatures generally between 0 and 35 below zero — the temperature where supercooled water droplets begin to spontaneously freeze in a process referred to as homogeneous nucleation — can freeze on contact and thus possibly impact aircraft weapons and sensors or control surfaces effecting flight safety.
Altocumulus clouds are relatively thin mid-level clouds that cannot be reasonably resolved in current atmospheric models. To mitigate their potential impact on Navy and Department of Defense operations, these clouds must be better parameterized said Dr. Jerry Schmidt, meteorologist, NRL MMD Mesoscale Modeling Section.
In previous ground breaking research, Schmidt discovered that the MCR — a very high resolution C-band dual polarization radar — is precise and versatile enough to resolve individual ice crystals and raindrops within clouds, making it a unique research tool.
In collaboration with Dr. Piotr Flatau of Scripps Institution of Oceanography and independent radar consultant Robert Yates, the team analyzed coincidental aircraft observations, ground-based instrumentation readings, and radar data from the MCR to document the structure of a thin and narrow band of mixed-phase altocumulus clouds.
The group then analyzed the diabatic heating and cooling structure of the altocumulus layer associated with the vertical flux divergence of the longwave and shortwave radiation as well as the evaporation and sublimation of liquid and ice particles over a deep virga layer that extended 1500 meters below the cloud base. When analyzing the high-resolution observations of the real-world atmosphere, the study found that actual observed processes did not precisely match with existing cloud formation and dissipation theories.
In particular, it was found that the presence of layer-wide horizontal gradient in the cloud top radiative cooling rates — associated with the magnitude of the cloud liquid water content — creates a circulating flow in the atmosphere, Schmidt said. This directs warm and dry air downward over the central portion of the narrow altocumulus cloud band, which begins to evaporate the interior cloud liquid water. Ultimately, the cloud's longevity or demise then hinges on whether or not a quasi-balanced state can arise between the water production terms within the cloud layer and the radiatively-induced mesoscale subsidence circulation the liquid production ultimately creates.
Fully analyzed results and follow-on field experiments will enable NRL scientists to better understand and model the composition, generation and decay of mid-level, and eventually low and high level clouds. The goal is to develop the capability to provide more accurate tactical scale cloud information to Navy and Department of Defense (DoD) mission planners and warfighting decision makers in support of global operations.
Funded by the Naval Surface Warfare Center, Dahlgren, Va., the project will continue to investigate the potential for these results to be applied to larger-scale thicker and warmer stratiform clouds, as well as higher and colder cirrus clouds. In summer 2015, the group plans to add UAS-based sensors, CLOUDSAT radarand satellite-based LIDAR measurement, and additional surface instrumentation, such as a microwave radiometer, to the next field studies. | <urn:uuid:1ee654ca-4fa8-47fb-8034-581a90646016> | 2.96875 | 942 | News (Org.) | Science & Tech. | 20.578978 | 95,522,895 |
The Atmospheric Infrared Sounder or AIRS instrument aboard NASA’s Aqua satellite captured an infrared image of the temperatures in Tropical Storm Andrea’s cloud tops on June 6 at 2:41 a.m. EDT. The coldest cloud top temperatures (in excess of -63F/-52C) and heaviest precipitation was over the eastern Gulf of Mexico and southeastern Florida at the time of the image.
This infrared image of the temperatures of Tropical Storm Andrea’s cloud tops was taken by the AIRS instrument aboard NASA’s Aqua satellite on June 6 at 2:41 a.m. EDT. The dark purple indicates coldest cloud top temperatures (in excess of -63F/-52C) and heavy rainfall. At that time, most of the heaviest precipitation was over the eastern Gulf of Mexico and southeastern Florida. Credit: NASA JPL, Ed Olsen
NASA’s Tropical Rainfall Measuring Mission or TRMM satellite flew directly above tropical storm Andrea on Thursday, June 6, 2013 at 0508 UTC (1:08 a.m. EDT). This orbit showed that Andrea had a large area of moderate to heavy rainfall in the northeast quadrant of the storm and precipitation was spreading over the state of Florida.
At NASA’s Goddard Space Flight Center in Greenbelt, Md. Hal Pierce of the TRMM Science Team used TRMM data create a 3-D view of Tropical Storm Andrea. The 3-D view from the west was derived from TRMM Precipitation Radar (PR) data captured when Andrea was examined by the TRMM satellite with the June 5, 2234 UTC (6:34 p.m. EDT) orbit. It clearly showed that the majority of the heavy convective rainfall was located on Andrea's eastern side. TRMM PR also showed that the tallest convective thunderstorms reached heights of about 14km (~8.7 miles).
On June 6, at 2 p.m. EDT, Tropical Storm Andrea was located near 29.0 north and 83.6 west. That's just 35 miles (55 km) west-southwest of Cedar Key, Fla. and 100 miles (160 km) east-southeast of Apalachicola. Andrea's maximum sustained winds were near 60 mph (95 kph) and had slightly increased forward speed, moving northeast at 17 mph (28 kph). Minimum central pressure is 994 millibars, down from 997 millibars during the morning hours.
At 2 p.m. EDT, the National Hurricane Center noted that the center of Andrea will reach the coast of the big bend area of Florida in the next few hours.
A Tropical Storm Warning is in effect for the west coast of Florida from Boca Grande to Indian Pass, from Flagler Beach, Fla. to Cape Charles Light, Va., the Pamlico and Albemarle Sounds, and the lower Chesapeake Bay south of New Point Comfort, Va. For the most up to date forecasts, visit the National Hurricane Center web page at: www.nhc.noaa.gov.
Andrea is expected to move northeastward after crossing Florida and travel near the east coast of the United States through Saturday, June 8.Text credit: Hal Pierce/Rob Gutro
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Researchers demonstrate that current models underestimate role of subsurface heterogeneity
A team of international researchers led by University of Freiburg hydrologist Dr. Andreas Hartmann suggests that inclusion of currently missing key hydrological processes in large-scale climate change impact models can significantly improve our estimates of water availability. The study shows that groundwater recharge estimates for 560 million people in karst regions in Europe, the Middle East and Northern Africa, are much higher than previously estimated from current large-scale models.
A karst region in Andalusia, Southern Spain. Photo: Matías Mudarra, Universität Malaga/Spanien
The scientists have shown that model estimates based on entire continents up to now have greatly underestimated in places the amount of groundwater that is recharged from fractions of surface runoff. This finding suggests that more work is needed to ensure sufficient realism in large-scale hydrologic models before they can be reliably used for local water management. The team has published their research findings in the scientific journal “Proceedings of the National Academy of Sciences (PNAS).“
Groundwater is a vital resource in many regions around the globe. For managing drinking water, the recharge rate is an important quantity for securing sustainable supplies. The researchers have compared two hydrological models that simulate groundwater recharge. One is a long-established global model with limited accounting for subsurface heterogeneity.
The other is a continental model the researchers have developed themselves that includes, for example, variability in the thickness of soils and different subsurface permeabilities. They have carried out the comparison for all of the karst regions in Europe, North Africa and the Middle East. Karst regions are known for their great degree of subsurface heterogeneity, because carbonate rock shows greater susceptibility to chemical weathering – a process that is known as karstification.
Karstification leads to varying soil depths and permeabilities. A comparison of the models' calculations with independent observations of groundwater recharge at 38 sites in the regions has shown that the model that accounts for heterogeneity produces more realistic estimates.
The researchers explain the reason for the difference between the two models as follows: In simulation, their newly developed model shows reduced fractions of surface According to the new model, a farmer in the Mediterranean region would potentially have up to a million liters more groundwater for extraction available in a year than the established model estimates, dependent on actual subsurface composition and the water demands of the local ecosystems.
When applied to the example of karst regions, the researchers' approach shows how it is possible to adapt global models used to predict water shortages, drought or floods to account more realistically for regional conditions. Scientists from the University of Freiburg, Canada's Victoria University, the University of Bristol in England and International Institute for Applied Systems Analysis in Austria took part in the study.
Hartmann, A., Gleeson, T., Wada, Y., Wagener, T., 2017. Enhanced groundwater recharge rates and altered recharge sensitivity to climate variability through subsurface heterogeneity. In: “Proceedings of the National Academy of Sciences”; doi:10.1073/pnas.1614941114.
Dr. Andreas Hartmann
Chair of Hydrology
University of Freiburg
Rudolf-Werner Dreier | Albert-Ludwigs-Universität Freiburg im Breisgau
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On the 25th anniversary of the project that brought the large blue butterfly back from extinction in the United Kingdom, ecologists are for the first time publishing the decades of research that helped them rescue this spectacular butterfly.
The study shows how the large blue's extreme dependence on a single ant species led to the butterflies' demise, as their habitat became overgrown, causing soil temperatures to drop and ant numbers to diminish. Before this discovery, butterfly collectors were generally blamed for the decline of this butterfly, also known as Maculinea arion.
The research, by Jeremy Thomas of the University of Oxford in Oxford, UK and the Centre for Ecology and Hydrology in Wallingford, and his colleagues, will be published online by Science, at the Science Express website, on 18 June 2009. Science is published by AAAS, the nonprofit, international science society.
"This study tells the story of a remarkable, 40-year research effort that began with painstaking fieldwork -- including the counting of individual butterfly eggs laid on flowers in the English countryside -- and culminated with a major conservation victory. Science is delighted to be publishing this impressive body of work, and we expect that the peer-reviewed data will be an important tool for future conservation efforts," said Andrew Sugden, Deputy and International Managing Editor at Science.
"Human beings are so much larger than insects, it's very hard for us to appreciate that what to us is an imperceptible change in habitat can have devastating consequences for a species like the bizarre and beautiful large blue butterfly. A difference of a centimeter in grass length can change the soil temperature by 2 or 3 degrees C. If you're the size of an ant or butterfly that difference is massive," said Thomas.
In the 1970s, the International Union for Conservation of Nature selected three butterflies, including the large blue, as global flagships for the cause of lepidopteran conservation. These insects and others had been mysteriously disappearing for decades, despite attempts to save them.
The large blue butterfly was selected because of its beauty and prize-status for collectors, and because of its unusual life cycle, according to Thomas.
Adult M. arion females lay their eggs on thyme flowers in the summer. After hatching, the caterpillars stay very small and many eventually fall to the ground. They secrete chemicals that attract red ants and fool them into thinking the caterpillars are ant grubs. The ants then carry the tiny caterpillars into their underground nests.
In most cases, only caterpillars that have landed in the nest of one particular ant species, Myrmica sabuleti, will survive to adulthood. The caterpillars' secretions are a sufficiently close match to those of M. sabuleti grubs that the ants never discover that they have been duped, and instead continue to protect the caterpillars for 10 months even though they are feeding on the ants' own brood. In early June, the caterpillars form a chrysalis near the colony entrance and then emerge to crawl aboveground two weeks later as butterflies.
While ecologists generally knew about this life cycle, the butterfly's intense dependence on M. sabuleti ants only came to light once Thomas began studying Britain's last surviving large blue butterfly colony.
"It was the nearest insect equivalent to living with the apes, I suppose," said Thomas.
"From May to late September, I was living with the last UK colony, measuring everything, including their behavior, how many eggs they laid, the survival of individual eggs, how many caterpillars were in the plants. It was a bit like a detective story."
The butterflies finally disappeared from Britain in 1979.
Thomas compiled this information into life tables, which show the number of new eggs and those that survived each year from 1972 to 1977, and which are now being published for the first time in the Science study.
With these field data, Thomas and his coauthors explored the possible factors that could be causing the butterflies decline. They realized that the grass in the butterflies' habitat had grown too long, as farmers had gradually stopped grazing their livestock on these hillsides and a viral infection had killed many of the wild rabbits in the 1950s.
The soil on these overgrown grasslands was therefore too cool to support adequate numbers of M. sabuleti ants. And, without enough ants to raise their young, the large blue butterflies dwindled. The researchers combined these ecological relationships into a numerical model, which is also being published for the first time in the Science study.
"I've been saving this paper up, as it were, for 25 years. None of the data points have been published. The life-cycle data and the life tables generated a model upon which all our conservation efforts were based. The description of this model is also new. There are few known examples of a model being able to predict the success of a conservation effort as well as ours did, for any insect," Thomas said.
In the late 1970s, after 40 years of trying to save the large blue by fending off butterfly collectors, conservationists followed Thomas' recommendations and restored the butterfly's proper habitat by clearing scrub and reintroducing grazing animals.
Starting in 1983, Thomas and his colleagues began introducing large blue butterflies imported from Sweden, into restored habitat sites. As of 2008, the butterflies occupied 30 percent more colonies than they had in the 1950s, before the major decline began. The large blue is now one of just three UK butterflies on course to meet the Convention of Biological Diversity's target to reverse species' declines by 2010. This rebound has closely followed the predictions generated by Thomas' model.
The picture in the rest of Europe is hazier, with the butterflies faring better in some countries than others. The data in this paper lay out the basis for similar restoration efforts for other butterflies with specific host requirements, such as the four related, globally threatened, species of large blue that are already starting to benefit from this approach across Europe, and the recovery of the Adonis blue butterfly from the brink of national extinction in the UK, according to Thomas.
He said that, while conservation efforts used to tend to focus on adult butterflies, this research has shown that the needs of juveniles are often much more specific and can primarily drive a population's overall health. Being aware of this fact may allow ecologists to take a shortcut around compiling the time-consuming life tables that are traditionally the first step in understanding why a species is declining.
Restoring the large blue's habitat may also provide collateral benefits for other species that live there, the authors speculate in their study. On some of its conservation sites there have already been dramatic increases in rare birds, plants and other butterflies, such as the wood lark, pale heath violet and the pearl-bordered fritillary, Thomas said.
Prof. Thomas' coauthors are David Simcox of the Centre for Ecology and Hydrology in Wallingford, UK and Ralph Clarke of the Centre for Ecology and Hydrology in Wallingford, UK and Bournemouth University in Poole, UK. The paper is entitled, "Successful Conservation of a Threatened Maculinea Butterfly."
This research was funded by EU Macman and Biodiversa (CLIMIT) programs, Natural England, CEH, National Trust, Somerset Wildlife Trust, Network Rail, J&F Clark Trust, Butterfly Conservation, Gloucester Wildlife Trust, Millfield School, Defra, WWF, Sir Terence Conran, Holland & Barrett, Hydrex, ICI, and R Mattoni.
The American Association for the Advancement of Science (AAAS) is the world's largest general scientific society, and publisher of the journal Science (www.sciencemag.org). AAAS was founded in 1848, and serves some 262 affiliated societies and academies of science, serving 10 million individuals. Science has the largest paid circulation of any peer-reviewed general science journal in the world, with an estimated total readership of one million. The nonprofit AAAS (www.aaas.org) is open to all and fulfills its mission to "advance science and serve society" through initiatives in science policy; international programs; science education; and more. For the latest research news, log onto EurekAlert!, www.eurekalert.org, the premier science-news Web site, a service of AAAS.
Natasha Pinol | EurekAlert!
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Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
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April 28, 2017 10:00 am
Solar energy is regarded as one of the energy sources of the future, and is the focus of numerous research and development projects worldwide. For instance, in April 2017 scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) announced the development of a photoelectrochemical cell capable of capturing excess photon energy normally lost to generating heat. This was made possible by using quantum dots and a process called Multiple Exciton Generation. For this reason, the IATE Term of the Week is quantum dot solar cell.
According to the Merriam-Webster online dictionary, a quantum dot (QD) is ‘a semiconductor nanocrystal exhibiting quantum mechanical effects that allow it to mimic the properties of an atom’.
As stated by Lakshminarayanan and Bhattacharya (2015), quantum dot solar cells (QDSC) are produced using quantum dots, which are usually made with materials such as CdS, CdSe and Sb2S3. They contribute to the development of low cost cells, as they involve simple chemical reactions, and also help to improve efficiency, since they ‘can emit more than one electron for every photon absorbed’. Still, Lakshminarayanan and Bhattacharya claim (2015: 138) there are difficulties in the efficient production of quantum dot solar cells.
Quantum dot solar cells have been the focus of much research, and efforts are being made to improve the technology and solve efficiency issues.
The European Union environmental policy attaches considerable importance to the development and use of renewable energy sources, including solar energy. The Treaty on the Functioning of the European Union states that ‘Union policy on energy shall aim, in a spirit of solidarity between Member States, to […] promote energy efficiency and energy saving and the development of new and renewable forms of energy.’
The EU has recently funded a 2-year research project which focuses on quantum dot solar cell technologies for space and green energy. The 1 million EUR TFQD project will run until the end of 2017. According to Professor Liu from UCL, who is involved in the project, favourable power-to-weight ratio and high efficiency will allow the thin-film light-trapped enhanced quantum dot solar cells to bring breakthrough innovation in the design of solar arrays: mass and area saving as well as flexibility will result in miniaturisation, power consumption reduction, increased efficiency, versatility, and functionality of future satellites. The research also paves the way for new opportunities in the terrestrial renewable energy sector.
Here you can see the entry for quantum dot solar cell in IATE:
We invite you to check some previous IATE Terms of the Week which are related to renewable energy and solar energy:
Clara Gorría Lázaro – Translator-Terminologist and Terminology Trainee at the Terminology Coordination Unit of the European Parliament,
and Yelena Radley, Terminology Trainee at the Terminology Coordination Unit of the European Parliament.
- Bush, Steve (2017) ‘Quantum dot solar inefficiency source found’, Electronics Weekly. Available at: http://bit.ly/2q5tkHs (Accessed 26 April, 2017)
- DOE/National Renewable Energy Laboratory (2017) ‘Researchers capture excess photon energy to produce solar fuels’, Science Weekly. Available at: http://bit.ly/2plJcI7 (Accessed 26 April, 2017)
- Lakshminarayanan, Vasudevan and Bhattacharya, Indrani (eds) (2015) Advances in optical Science and Engineering: proceedings of the First International Conference, IEM OPTRONIX 2014. New Delhi: Springer.
- Official Journal of the European Union (2012) Consolidated version of the Treaty on the Functioning of the European Union, Article 194(1c), CELEX:12012E/TXT. Available at: http://bit.ly/2q9URHU (Accessed 27 April, 2017)
- TFQD Project (n.d.), ‘Thin Film light-trapping enhanced Quantum Dot photovoltaic cells: an enabling technology for high power-to-weight ratio space solar arrays’, TFQD Project Website. Available at: https://tfqd.eu/ (Accessed 26 April, 2017)
- UCL Department of Electronic & Electrical Engineering (n.d.) EU H2020 Grant Award. Available at: http://bit.ly/2q6m9yY (Accessed 26 April, 2017)
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Objective The objective of this experiment is to perform a steam distillation using a microscale distillation apparatus and isolate a natural product from cloves. Introduction By performing steam distillation we can isolate eugenol at lower temperature than its usual boiling point of 248 degree Celsius. Eugenol belongs to a category called essential oil. Many of these compounds are used as flavoring and perfumes and in the past were considered the essence of plant from which they were derived. Structure of eugenol (clove oil) and eugenol acetate: Reagents: Eugenol, CH2Cl2, Br2, FeCl3, Methanol
Procedure: Co-distillation We first combine 15 mL of water with 1 g of crushed, ground cloves in a 25-mL round-bottom flask. Then added a spin bar to the 25-mL round-bottom flask and assembled the microscale distillation apparatus. We made certain that the ground cloves were well wetted. We maintained the temperature of the sand bath at approximately 130 °C and wrapped the bottom of the still with aluminum foil. Then periodically transfer the distillate from the Hickman head to a 15 mL screw cap centrifuge tube and continue the steam distillation until 5–8 mL of distillate have been collected.
Then we started the extraction process by adding 2 mL of CH2Cl3 to the water–eugenol emulsion. Cap the tube and shake it frequently. We then allowed the layers to separate and transferred the CH2Cl2–eugenol solution to a clean, dry 5- mL conical vial. We made sure no water was transferred in this step. Then we added 1 mL of CH2Cl2 to the water–eugenol emulsion, cap and shake the tube. Allowed the layers to separate and transfer the CH2Cl2–eugenol solution to the 5-mL vial used previously and made certain that no water is transferred during this step.
We then added 1 mL of CH2Cl2 to the water–eugenol emulsion and shook the tube. We allowed the layers to separate and transferred the CH2Cl2–eugenol solution to the 5-mL vial used in previous step. We made certain that no water was transferred during this step. Finally we finished the co distillation process by drying the CH2Cl2–eugenol solution with 2-3 microspatulas of anhydrous sodium sulfate. Evaporation Transfer the dried CH2Cl2–eugenol solution to a clean, dry, tared, 5-mL conical vial. And rinse the drying agent with a few drops of CH2Cl2 and transfer CH2Cl2 rinse to the 5- mL conical vial.
In a fume hood, evaporate the CH2Cl2 using a hot water bath at approximately 40 °C max 55 °C. Classification Test of eugenol (clove oil) The eugenol isolated will be tested for unsaturation using the Br2Test and aromaticity with the ferric chloride test. Br2 Test First we dissolved the clove oil in 2? 3 mL of methanol then added 5 drops of clove? oil solution to a test tube. Then we added few drops of Br2 reagent and gently swirled and recorded our observations. W then prepared a control slide and matched our results to it. FeCl3 test
Dissolved the clove oil in 2? 3 mL of methanol Added 5 drops of clove? oil solution to a test tube Added a few drops of FeCl3 solution to test tube Gently swirled and record your observation Results and Calculations: Br2 test results. Original Br2 was yellow in color but when it was added to our solution it turned colorless. This shows that we had double bonds formation. Benzene gives us double bonds. Our results matched the result we obtained when we compared with control that we had created. FeCl3 test results: Our solution turned light yellowish in color.
Control was dark orange in color. Discussion: Our benzene results indicated that we had double bonds formation. Benzene gives us double bonds. Our results matched the result we obtained when we compared with control that we had created. Our FeCl3 test gave us light yellowish color solution while the control was somewhat orange. This could probably mean that we had Eugenol acetate instead of Eugenol. References: Introduction to Organic Laboratory Techniques: A Microscale Approach. Pavia, Lampman, Kriz, and Engel. (1999) Saunders College Publishing. | <urn:uuid:26308952-e481-4332-a0e2-88ff18bc76a3> | 3.609375 | 951 | Academic Writing | Science & Tech. | 54.612263 | 95,522,922 |
In this section we will learn about the JSP elements that we can use on a JSP page. This section will describe you all types of JSP elements that we can use on JSP page.
JSP elements are called the JSP tags on JSP page. On the JSP page mainly three groups of JSP elements are used :
JSP Scripting Elements
JSP Scripting Elements are used for writing the Java Code inside the JSP page. There are different types of scripting elements these elements are used for various purposes. Following are the scripting elements :
JSP Directive Elements
Directive elements in JSP provides the special information to the JSP engine. It gives the information about the JSP page. Each JSP page goes through the two phases i.e. translation phase and request time phase. At the translation phase JSP page is translated into a Servlet. The JSP engine translates the JSP page into a Servlet, directive elements are handled at the translation time. These directives are translated to the Servlet only for once, until there is no changes made to the directive elements in the Servlet.
JSP Directive Elements can be declared within the following special characters '<%@ %>'. Syntax for using directive in the JSP page is as follows :
<%@ directiveName attr1="value1" attr2="value2" %>
JSP Standard Action Elements
JSP Action Elements are used to take action on the basis of some information. These action elements can create, modify or use the other objects. Action elements are coded with the strict syntax they are used to apply the built-in functionality. Action elements are represented as <jsp:tagName> </jsp:tagName>. Code is written inside these tags, the <jsp:tagName> specifies the starting of the action tag where as the action tag is ends with </jsp:tagName>. When you are not required to defined the body of the tag you may end up the action tag by <jsp:tagName/>
JSP Comment Elements
JSP comment elements are used to hide your code from the "view page source". However, you can use HTML comment tags in JSP page but, when user of your website will choose the "view page source" then they can see your commented code. The JSP comment is denoted by the special character <%-- --%>. The special character '<%--' specifies the opening comment element and the special character '--%>' specifies the end of the comment tag.
HTML comment tag is denoted by the special characters '<!-- -->' where, '<!--' specifies the start tag and '-->' specifies the end tag. | <urn:uuid:70df11df-97f7-432d-8d87-ce7a6b2c3a59> | 3.09375 | 567 | Documentation | Software Dev. | 51.678533 | 95,522,933 |
Fast Facts: What are spawning horseshoe crab surveys?
You can think of horseshoe crabs as “living fossils” - they have been around since the age of the dinosaurs. In modern times, their unique blue blood has become important to the biomedical industry to test for impurities in drugs, and they serve as bait in the eel and whelk fisheries. However, their population is in jeopardy due to overharvesting, and many states along the Atlantic coast have developed programs to manage their horseshoe crab populations.
In spite of this interest, little is known about the population of horseshoe crabs in New Hampshire’s Great Bay Estuary. This lack of information is critical, and citizen scientists are playing a big role in filling in this missing knowledge. In 2012 and 2013, volunteers partnered with UNH researchers to survey spawning horseshoe crabs using methods that are consistent with State agency surveys. After a two-year hiatus, the project has returned for 2016 and 2017.
Volunteer Description: What do horseshoe crab survey volunteers do?
Volunteer Experience: Horseshoe crab survey volunteers will sign up for survey shifts, which take place once daily, seven days per week, scheduled to correspond with low tides. Volunteers will work with a UNH researcher to look for and count spawning horseshoe crabs.
Time Frame: After being trained, volunteers can sign up to fill horseshoe crab survey shifts. Each shift takes about 15 minutes to complete, and volunteers can sign up for as many or as few shifts as they’d like.
Project Impacts: Data collected during horseshoe crab surveys directly contributes to ongoing UNH research.
Qualifications: Interest in finding and counting horseshoe crabs in their natural environment
- Learn about and observe a fascinating coastal species
- Contribute to the knowledge and management of the Great Bay’s horseshoe crab population
Questions? For more information or to become involved in volunteer horseshoe crab surveys, contact Caitlin.
Upcoming Opportunities: Join our spawning horseshoe crab survey efforts!
The 2018 horseshoe crab survey is in full swing! Contact Caitlin for more information on how to become involved.
Learn More: Links, resources, and partner organizations
Check out this publication from NH Fish and Game about the fascinating life cycle of horseshoe crabs, and read this summary of some of the findings that have emerged from past volunteer horseshoe crab surveys!
Stay in touch with the Great Bay horseshoe crab project by following their Facebook page. | <urn:uuid:effc1997-0b90-4a59-8c69-655d57bfd6b0> | 3.53125 | 532 | Knowledge Article | Science & Tech. | 40.929992 | 95,522,935 |
Environmental Impact Assessment (EIA) is a policy and management tool for planning and decision-making. Conceived in the 1970s after the United Nations Conference on the Environment in Stockholm, EIA assists policy makers and the general public in identifying, predicting, and evaluating the environmental impacts and consequences of proposed development projects, plans, and policies. The outcome of an EIA study helps to decide whether a given project should be implemented and what form it should take.
This volume includes an introduction to EIA, and explains its processes, methods, and tools. It discusses the implementation of specific environmental management measures and the need for their constant monitoring. The authors also consider the writing and reviewing of EIA reports and the process of translating and communicating the findings of EIA studies to decision-makers and the public. The book also examines emerging trends in EIA and concludes with a number of illustrative case studies.
Asit K. Biswas and Cecilia Tortajada, 2018, Hydropower & Dams Journal [...]
James Horne, Cecilia Tortajada and Larry Harrington, 2018, Internatio [...]
Rosario Sanchez, Laura Rodriguez and Cecilia Tortajada, 2018, Journal [...] | <urn:uuid:c9eaccc1-f203-49b7-8b9a-b67fa5dfeec9> | 3.296875 | 243 | Content Listing | Science & Tech. | 31.117941 | 95,522,952 |
Historic discovery of solar seismic waves after 40 year search reveals the sun's core is rotating four times faster than its surface
Scientists have detected ‘convincing proof’ of an elusive type of seismic wave in the sun, helping to solve a decades-long mystery on the movement of material at the core.
While experts have long suspected gravity waves could be a key component of the core’s rotation, they’ve so far been unable to pinpoint them, despite four decades of searching.
Now, using ESA and NASA’s Solar and Heliospheric Observatory, scientists have finally found evidence of these low-frequency waves, revealing the core spins much faster than the sun’s surface.
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HOW THEY DID IT The researchers... read more
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- 21:03 Why making pitchers bat is one of baseball's most beautiful facets | <urn:uuid:1da9fd8f-c646-45ac-b2da-98a31df3293e> | 2.953125 | 690 | Truncated | Science & Tech. | 68.008546 | 95,523,012 |
Science looks at unusual experiments
The progress of physics requires the
collaboration of both experimentalists and
theorists; only the rare physicist, such as Enrico
Fermi, has been successful at both lines of work.
Experimental physicists often
exercise great ingenuity to arrange instrumented
events that can either verify or falsify the clever
ideas of their theoretical friends, who return the
favor by laboring to fold the experimentalists’ most
improbable findings into their theories.
At Washington University in St. Louis
this semester, the Department of Physics and
University College, both in Arts & Sciences, will
describe a few of the experimentalists’ greatest
successes. Four lectures on great physics
experiments will be held at 10 a.m. on four
consecutive Saturday mornings, March 10–31, in the
Hughes Lecture Room, Room 201 in Crow Hall.
Presented by faculty members of the
physics department and tailored for the general
public, the lectures are free and open to the
The Saturday Science lectures have
been organized since their inception 19 years ago by
Michael Friedlander, PhD, professor of physics.
Friedlander, an experimentalist who
studies cosmic rays and infrared and gamma-ray
astronomy, has also written about pseudoscience and
the conduct of science. He feels that scientists
have an obligation to engage the public.
“As scientists,” he says, “we have an
obligation to explain to the non-expert public what
we are doing, what is exciting about our findings
and where we think all of this may lead.
“In this way, we would hope that the
public would gain some understanding of the methods
of science, be willing to continue to support our
efforts and will also not try to impose ideological
restrictions to what we may study.
“History shows that none of this
should be taken for granted,” he says.
March 10, “The Discovery of Cosmic
Rays and What They Are,” Martin Israel, PhD,
professor of physics
This year, 2012, is the centennial of
the discovery of cosmic rays – ionizing radiation
bombarding the Earth from space. Israel will
describe the early balloon observations by Victor
Hess, who showed that the radiation was coming from
space rather than originating on Earth.
WUSTL and NASA balloon-borne experiment to
measure the elemental abundances of galactic
Twenty years later, through his
worldwide cosmic ray survey, WUSTL’s Arthur Holly
Compton was able to show that the cosmic rays were
not “rays” but rather were charged particles.
Meanwhile, in studies of cosmic-ray particles in the
laboratory, Carl Anderson found a positively charged
electron — the theoretically-predicted “positron,”
and in 1936 Hess and Anderson shared the Nobel Prize
March 17 “The LHC and the search for
the Higgs,” Michael C. Ogilvie, PhD, professor of
An essential component of experiments
that explore the internal structure of atomic nuclei
are beams of high-speed nuclei. These are
accelerated and made to collide. Debris from their
collisions is examined and provide the clues being
simulation of the debris that would result if a
collision at the collider in Geneva did produce
a Higgs particle.
Ogilvie will describe experiments in
progress at the Large Hadron Collider (LHC) in
Geneva, where the existence of the predicted Higgs
particle might be demonstrated.
March 24, “The Lamb Shift,” John
Rigden, PhD, adjunct professor of physics
Rigden will describe the Lamb Shift,
named for Willis Lamb who was awarded the Nobel
Prize for experiments that explored the internal
energy of the hydrogen atom.
March 31, “The Ingenious Experiments
of Baron Roland von Eötvös,” Ramanath Cowsik, PhD,
professor of physics and director of WUSTL’s
McDonnell Center for the Space Sciences
The Eötvös experiment, planned by
Baron Roland Eötvös in the early years of the 20th
century, provides deep insights into the nature of
gravity, and Einstein drew on these experimental
observations as he formulated his General Theory of
For more information, contact Sarah
Hedley at (314) 935-6276 or visit physics.wustl.edu.
Click “Seminars/Events” and then “Saturday | <urn:uuid:20c847c3-ad4e-483b-965b-f11da24e2c18> | 3.1875 | 1,010 | News (Org.) | Science & Tech. | 33.556474 | 95,523,021 |
In our previous tutorial, we learned how to work with local git repository. We followed some of the steps below:
- we created a new project directory
- we initialized local git repo
- we added some files to our local git repo
- we committed file changes to our local git repo
What is remote git repository?
A remote git repository is nothing but a space in a remote computer which allow us to manage our project. A benefit of having a remote git repo are followings:
- multiple developers can work remotely on same repo
- you can push your local file changes to server
Think about this way if you only have a local git repo and what if something went wrong with your computer? What if you want other developers to work on the same project?
In this tutorial I will use github as a remote server to manage my remote git repository. If you want to play with github create a new account using following link:
How to create a github repository?
Log on to your github account. Click on + icon located on top right corner to create a new remote git repo as shown in image below:
Click on New Repository menu item. You will now see a screen shown below where you need to put repostory name, description (optional), select public or private and hit Create Repository button:
Next, it will create a new blank repo and will take you to the following screen. It will gives you following two options:
- creating a new repo
- adding existing repo
In our previous tutorial, we created a local git repostitory. We want to add that local git repo to our newly created git remote repo.
Let's make our local git repo to be aware of our newly created remote git repo. So that you can push your local git changes to remote git repo.
How to add remote git url?
Let's go to our local git repo and run commands one by one shown in above screen shot:
# add remote git repo url to local git repo git remote add origin firstname.lastname@example.org:phpcodebooster/git-tutorial.git # check the status of remote repo git remote -v # above command will output something like below origin email@example.com:phpcodebooster/git-tutorial.git (fetch) origin firstname.lastname@example.org:phpcodebooster/git-tutorial.git (push)
Now, out local git repository is aware of remote repo. Now, we can do following tasks with remote repo:
- we can fetch new changes from remote repo
- we can push new changes to remote repo
How to fetch remote changes using git?
Now, that we have a remote git repo and we know that it is empty. We have our local git repo with some files. Our task is to move our local git changes to remote git repo.
When we created a new remote git repo by default it creates a master branch. We are at beginners level so at this moment dont worry about branches and what are they we will learn them as we move on.
For now, just think that you have only one branch called master where you need to push your local git changes. We need to use fetch command to get all new changes from remote git repo.
Let's run following command to get all the data from remote git:
# fetch remote changes/refs git fetch # you can also use following # command instead of git fetch git pull
What is the difference between git pull and git fetch?
Git fetch will only fetch all the remote changes to local git repo.
Git pull will first fetch all the remote changes to local git repo and performs merge operation which means if you and other developer work on the same file and both made some changes. They will be merged together with git pull.
It is always recommended to perform git pull operation before you push any changes to remote server to avoid any incoming conflicts with code.
Let's move on, when you run git pull or git fetch with our newly created github repo you may see following error:
This error occur because you may not have write access to this remote repo. With write access you can commit your local git changes to remote git repo.
You need to generate a ssh key and add to your remote github repo to resolve this error by allowing write access for the given ssh key.
Follow the tutorial below to resolve this error:
Once you resolve your write access error. We can push our local git changes to remote server by running following command:
git push -u origin master
You will see following output with above command:
We have successfully pushed our local git changes to remote git repo.
What did you learn today?
You have gained following skills by following this tutorial:
- You learned about remote git repo
- You learned how to create a remote repo
- You learned how to add remote git repo url to local git repo
- You learned how to push local changes to remote git repo
In next tutorial, we will learn more about basic git commands.
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Though the general feeling is that of changes on climate will consequently affect ETc, the results have indicated that there is no significant effect of climate change on crop evapotranspiration, despite the fact that some climatic factors have changed. Applying Student’s T-test, the mean values for the most water intensive trees in Cyprus of the 1994-2004 decade have shown no statistical difference from the mean values of 2005-2015 decade’s for all the cases, concluding that the climate change taking place the last decades in Cyprus have either not affected the crop evapotranspiration or the crops have manage to adapt into the new environmental conditions through time.
ACCESS THE FULL ARTICLE
G. Papadavid, D. Neocleous, A. Stylianou, M. Markou, G. Kountios, D. Hadjimitsis, "Remote sensing applications for estimating changes on crop evapotranspiration of the most water intensive crops, due to climate change in Cyprus ," Proc. SPIE 9688, Fourth International Conference on Remote Sensing and Geoinformation of the Environment (RSCy2016), 96881S (12 August 2016); | <urn:uuid:d847f10f-0a44-4811-8845-b0b00f716d78> | 2.546875 | 244 | Truncated | Science & Tech. | 38.051411 | 95,523,044 |
Inspiring the next generation of scientists with their observations of quasars, black holes, Jupiter, and SETI with the Goldstone Apple Valley Radio Telescope, GAVRT
This paper describes a radio astronomy programfor schools, the Goldstone-AppleValley Radio Telescope,GAVRT. The GAVRT program is designed to bring the inspiration and enthusiasm to a younger generation of teachers and children who learn about science by doing real science, just as Iosif Shklovsky brought to an older generation.
Unable to display preview. Download preview PDF.
- 1.G. Jones, S. Weinreb, H. Mani, S. Smith, L. Teitelbaum, M. Hofstadter, T. B. H. Kuiper, W. A. Imbriale, R. Dorcey, and J. Leflang, Proc. of SPIE 7733, 77333O-1 (2010).Google Scholar
- 4.S. Horiuchi, C. Garcia-Miro, R. Rizzo, J. Forster, et al., EGU General Assembly, Held 2–7 May (Vienna, Austria, 2010), p. 13408.Google Scholar
- 5.D. L. Jauncey, J. E. J. Lovell, Y. Koyama, T. Kondo, S. Shabala, H. Aller, and M. Aller, European Week of Astronomy and Space Science (Turku, Finland, July 8–12, 2013).Google Scholar
- 6.M. J. Klein, D. J. Burns, C. F. Foster, M. F. Garyantes, S. Gulkis, S. M. Levin, E. T. Olsen, H. C. Wilck, and G. A. Zimmerman, Third Decennial US-USSR Conference on SETI, ASP Conf. Ser. 47, Ed. by G. Seth Shostak (1993).Google Scholar | <urn:uuid:57dad227-55d6-4c36-9a53-39c969a1c097> | 2.71875 | 424 | Truncated | Science & Tech. | 89.31509 | 95,523,052 |
The author is a physicist from the University of Milan, Italy. She has been working at the Central Research Laboratory (Gabriël Metsustraat 8, 1071 EA Amsterdam, The Netherlands) for the past year. The full report of this investigation is available at the Central Research Laboratory for Dfl. 50 (about $27).
The aim of this project was to investigate the state of the art of laser use on art objects.
In order to achieve this goal I have reviewed the basic ideas about lasers, listed the properties of the laser beam and studied the mechanism of light amplification. In my report I describe technical features such as the main pumping systems and the Q-Switched Operation Mode (a procedure using very short and intense pulses), as well as the working of optical fibers and the lasers commonly used in conservation: the ND:YAG and the excimer lasers.
I reviewed the means by which a laser beam is able to remove surface layers from a target material, an action called ablation, and saw that ablation is the result of the combined action of thermal, photochemical and mechanical processes.
First I focused my attention on the thermal model for laser ablation with infrared lasers used in the normal operation mode on stone objects. In this case the phenomenon is fully understood: The laser light vaporizes a black crust but does not damage the underlying stone because it is almost completely reflected. When the laser is used in the Q-Switched Operation Mode, with very short and intense pulses, it is necessary to take into account effects such as the blocking of the laser light by the dust plume and the mechanical effects generated by the expanding plasma and the rapid heating of the target material.
I then reviewed current ideas about UV laser ablation. In this case, photochemical effects have to be taken into account because the energetic UV photons are able to break molecular bonds in the target material. In recent years, researchers in the field of laser cleaning of art objects have been turning to the use of UV lasers because the thickness of the layer removed by a single pulse is very small.
Workers in this field have used a variety of analytic techniques to characterize the state of the artifact before and after laser action, and to monitor the ablation mechanism online. These techniques are described in the last chapter of the project report. I tried to focus attention on which kind of information these techniques can provide.
An extensive literature review was carried out for this project. The different papers are summarized in a series of tables in the report. The use of infrared lasers on stone objects has been extensively studied: eleven papers were found on this subject. However, only three papers on the use of UV lasers were found, apart from the abstracts of the papers presented at the LACONA conference (LAsers in the CONservation of Artworks) held in Crete in October 1995.
Even if the use of lasers on stone objects seems efficient for cleaning purposes, and even if the use of UV lasers seems promising on a number of different substrates, two main issues are still waiting to be addressed: the discoloration effect of the material beneath the layer removed, and the long-term effects subsequent to laser action.
A discoloration of the substrate has been noticed by a number of authors whether the substrate is a plain stone or a pigment layer on stone or on canvas. In this last case it has been verified that discoloration occurs both with infrared and UV lasers for almost all the commonly used pigments (cinnabar hematite, red ocher, massicot, vermillion, azurite, etc.) and that it occurs regardless of the media. So far the researchers have not been able to determine whether discoloration is a photothermal or a photochemical effect. More research is necessary to determine the exact causes of this phenomenon and to investigate which laser parameters (type of laser, operation mode, energy density, etc.) are most important in the control of discoloration.
The second issue that must be addressed is the long-term effect of laser action. The condition of the substrate has been studied mainly to check the effectiveness of the cleaning or the occurrence of immediate damage such as melting of stone or modification of its calcite structure. It is now important to determine whether the effects on the substrate (rapid heating of the substrate, shock wave pressure generated by the expanding plasma, breaking of chemical bonds due to UV radiation) could have long-term consequences on the substrate even if there is no immediate damage visible.
The reason for this investigation was the mounting interest of conservation in the possibilities of laser technology and the eagerness of the laser application industry to supply the equipment for application tests.
The main concern of the CRL obviously was for the safety of the objects, particularly in relation to the effects of laser radiation on the aging of materials.
As a result of this investigation we have come to the conclusion that on the basis of existing knowledge and evidence it may-after careful testing-be justified to use laser radiation on stone and related materials under certain conditions.
The CRL does not recommend experimentation with laser cleaning of paint or organic materials without further research into the above-mentioned effects.
Timestamp: Sunday, 03-Mar-2013 21:38:59 PST
Retrieved: Monday, 16-Jul-2018 00:55:39 GMT | <urn:uuid:1699decf-42cb-47bf-98f6-467592b47742> | 2.5625 | 1,094 | Academic Writing | Science & Tech. | 31.214558 | 95,523,061 |
Resources - Primary EO Method
High-concentration ethylene oxide analysis.
This is beautiful because it is so simple.
The vent gasses from the reactor and one or two other sources including the padded storage tanks which were vented whenever a tanker was unloaded, had high concentrations of Ethylene Oxide in them and were the source of the reason why I had to reanalyse them, just to make sure that they were correct.
Once it was pointed out to the Environment Agency (EA) that the levels of EO at the perimeter fence were, as stated by Deryck during 1993, in the order of ten times the legal limit, a response to the EA from Deryck stated that the original analysis was performed on a very old and inaccurate packed column gas chromatograph which he alleged had poor resolution and then claimed that the analysis was repeated on a GCMS which enabled the job to be performed more accurately.
The samples concerned were of the order of 30% EO with the only other component being nitrogen gas. There was no reason to use a chromatograph of any sort to separate anything out because there were no other chemicals in there, just the two.
Additionally, the concentration of EO was so high that it was easily detectable using a method other than chromatography chromatography really only starts to be useful at levels below a few percent in samples like this. As though that was not enough, chromatography is a secondary method you need to calibrate the machine using standard samples and therefore is not as accurate as the method I actually used, which is a primary method it is measured directly and needs no standards. In fact, this method is so robust that even if you are careless with it, you will still have an error of around a quarter of a per cent, whereas chromatography is around five and two per cent for packed columns and capillary columns respectively the massspectrometer of the GCMS only being a detector and not contributing to the accuracy GCMS is still a secondary method.
So, how does it work?
It works on the following points:
- EO is very soluble in water;
- there are only two components, the other (nitrogen) is not soluble in water to an extent that would interfere with the analysis;
- the concentration of EO in the sample is high; and,
- the pressures involved in the plant are low no more than 2psig.
This is what you do...
- Go on the plant with an evacuated 500ml sample tube.
- Flush the sample point by opening the valve.
- Put the sample tube in place on the silicone tube and open the tap to let the sample gas flow in.
- Once you have the sample, close the tap and then the valve optionally, you can open the other tap and let the sample gas blow through it for a few seconds before closing the taps and the valve.
- Take it back to the lab and let it cool down.
- a Weigh the sample tube on a balance to the nearest gramme (weight T).
- Put the end of the sample tube into a tub of running water and just crack open the tap to let out any pressure so that the pressure in the tube is at atmospheric pressure, ie the end of the tube is only just below the surface arguably you should get the tare weight at this point rather than the last but the difference in weight is so small and the tube would now need drying.
- Push the end of the tube down into the water so that some water enters the sample tube and the EO will immediately start to dissolve into it, reducing the pressure and sucking more water in there.
- Periodically close the tap and shake the water around in the tube, then immersing the end before opening the tap to let more water in. When no more water goes in, the EO is all absorbed and the only gas left in the tube is nitrogen.
- Raise the sample tube with the tap open until the level of the water on the inside is the same as it is on the outside and close the tap.
- b Dry off the tube and weigh it on a balance to the nearest gramme (weight N).
- Finally, open up both taps with the tube underwater and fill it completely with water. Close at least one of the taps so that water doesnt run out if you close both and then forget about it once you have finished, the water inside would warm up and expand, the resulting pressure can be enough to break the sample tube.
- c Dry off the tube and weigh the sample tube on a balance to the nearest gramme (weight G).
Now, take weight T off the other two weights and then divide one by the other like so...
Percentage EO = (N - T) / (G - T) x 100
The maths is easy, the rest of it is quick and as for errors, if you make sure that the pressure before you add the water is the same as the pressure in the lab, you might get an error of around 1 gramme or one part in 500 aka 0.2% which by far outshines any chromatographic methods even the primary method Janak when considering the volumes involved.
|With a tea pot in one hand and some shit to throw later on, this all seemed to suit Snaith rather well. He was happy. He was sort of smiling.| | <urn:uuid:81a9771c-dd50-48c0-a7ed-fef4709809aa> | 2.65625 | 1,119 | Tutorial | Science & Tech. | 50.947351 | 95,523,088 |
Forests form an integral part of the Kyoto Protocol on climate change because they act as terrestrial “sinks” to soak up the carbon emissions that are contributing to global warming. Countries that have ratified the protocol can offset their carbon emissions quota by planting trees, either at home or in developing countries. But how efficient is this “carbon trading” and how good are forests at absorbing these extra carbon emissions?
Nearly one hundred of the world’s leading experts on global warming will gather in Southampton from 1-4 April 2003 to share the results of their latest research on the role that forests can play in mitigating climate change. Bob Watson, Chief Scientist of the World Bank – the body overseeing global carbon trading - will open the symposium by examining the key part that ecology plays in global policies to ameliorate climate change.
Professor Howard Griffiths of the University of Cambridge will tell the symposium: “The remit for plant scientists is a hefty one. Not only do we need to quantify the capacity of global terrestrial carbon sinks, but we also need to critically assess the methods and models we use to make sure that our measurements are accurate and reliable enough to predict likely future levels of carbon.”
Sarah Blackford | alfa
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering | <urn:uuid:20a714d1-1011-4d20-bf1e-9d788ea0069f> | 3.46875 | 912 | Content Listing | Science & Tech. | 40.121649 | 95,523,096 |
Physical Fundamentals of Nanomaterials (Micro and Nano Technologies)
Bangwei Zhang Ph.D.
- 出版商: William Andrew
- 出版日期: 2018-02-21
- 售價: $5,272
- 貴賓價: 9.5 折 $5,008
- 語言: 英文
- 頁數: 486
- 裝訂: Hardcover
- ISBN: 0124104177
- ISBN-13: 9780124104174
Physical Fundamentals of Nanomaterials systematically describes the principles, structures and formation mechanisms of nanomaterials, in particular the concepts, principles and theories of their physical properties as well as the most important and commonly used preparation methods. The book aims to provide readers with a basic understanding of how nanomaterials are synthesized as well as their resultant physical properties it therefore focuses on the science of nanomaterials rather than applications, serving as an excellent starting point for researchers, materials scientists and advanced students who already possess a basic knowledge of chemistry and physics.
- Provides thorough coverage of the physics and processes involved in the preparation of nanomaterials
- Contains separate chapters for various types of synthesis methods, including gas phase, liquid phase, solid phase, and self-assembly
- Coverage of properties includes separate chapters on mechanical, thermal, optical, electrical and magnetic | <urn:uuid:4f586145-7903-4fc2-827d-69aaf46eb170> | 2.625 | 318 | Product Page | Science & Tech. | 10.785356 | 95,523,102 |
We’re Doomed: Scientists Have Invented Shapeshifting Liquid Metal, the T-1000 Draws Near
Come with me if you want to
live joke nervously and await our demise.
Because science won’t be happy until we’ve all been enslaved by our robot overlords, eaten by dinosaurs, and reanimated as zombies, researchers have made another breakthrough in bringing your nightmares to life and created shapeshifting metal. And here you were worried that we’d all be embarrassingly defeated by lowly T-800 models.
Researchers from North Carolina state university just weren’t happy with the fact that their liquid metal had a tendency to ball up into little, non-murderous spheres due to its high surface tension. So, they found a way to use an electric charge to change the surface tension and allow the liquid metal to flow into an amorphous blob of impending doom. But that wasn’t enough for them, either. They also found that reversing the polarity of the charge would reverse the effect and return the metal to its original, rigid state.
polymimetic gallium and indium liquid metal alloy doesn’t even need a very large electrical charge to undergo the change, so don’t go hoping the machines will need impractically powerful electrical sources to pull off their shapeshifting trick. The alloy’s surface tension changed with a charge of less than one volt.
They can even use electrical current to control the shape and movement of the alloy, as you can see in their not at all deliberately creepy video demonstration (complete with vaguely tense Final Fantasy VII music):
On the one hand, this is some really amazing science that could help with building adaptable electronics. On the other hand, I’m pretty sure that’s how we wind up with Skynet and nope, shut it down. Don’t do it, science. Don’t.
(via Gizmodo, image via Terminator 2)
- There’s also a self-healing polymer
- And some light-up robot skin
- And regular electronic skin, because that’s a thing we need | <urn:uuid:91472248-8fba-4533-8fed-b482f86ef52c> | 2.578125 | 458 | Personal Blog | Science & Tech. | 42.270593 | 95,523,103 |
For Mechanical Engineering Concepts in Kenya, energy is defined as the capacity to do work. An object may have mechanical energy by virtue of its position, internal structure or its motion. There are also other forms of energy save for mechanical, namely: chemical energy (found in foods, oils, charcoal, biogas etc. and is due to the kinetic energy and the potential energy of electrons within atoms), electrical energy (associated with the electric charge and can be produced by generators from hydroelectric power stations waterfalls, geothermal stations, nuclear fissions etc.), nuclear energy from a nuclear reactor, thermal energy (due to heat produced from burning fuels, the sun, heaters etc.). Engineering in Kenya has more articles.
In Mechanical Engineering Concepts in Kenya, it is a remarkable fact about our physical universe that whenever one form of energy is lost by a body/ system, this energy never disappears but is merely translated into other forms of energy e.g. vehicles burn fuel to produce both thermal (heat) and mechanical energy.
Mechanical Energy for Mechanical Engineering Concepts in Kenya
It is the energy of motion – whether that energy is in action or stored. It exists in two forms;
Kinetic energy in Mechanical Engineering Concepts in Kenya – this is energy possessed by a body by virtue of its motion and it represents the capacity of the body to do work by virtue of its speed. For Mechanical Engineering Concepts in Kenya, if a force F acts on an object of mass m such that the mass accelerates uniformly from initial velocity v1 to a final velocity v2 over a distance s; then, work done over the distance s is
W = FS. But F = ma, and S = ut + ½at2. From the relation v = u + at, then;
t = (v-u)/a so that the work done is W = ma.s = ½m (v2 – u2) = ∆ke which is the work-energy relation theorem. In Mechanical Engineering Concepts in Kenya, if a body starts from rest, then the work done on the object = kinetic energy gained by the object.
Potential Energy for Mechanical Engineering Concepts in Kenya
It is the energy possessed by a body by virtue of its configuration (position) in a force field e.g. gravitational field; magnetic field etc. if an object of mass m is lifted to a height h from the ground, then;
Work done on the mass W = F.h = mgh i.e. work done on the object = gain in the potential energy by the object. Whether a body falls vertically or slides down an inclined plane, the work done on it by gravity depends only on its mass and on the difference in height between the initial and final positions. Potential energy in Mechanical Engineering Concepts in Kenya of an object depends on its location and not by the route through which it arrived at that position.
It follows that if a body is transported around a closed path, the change in potential energy vanishes i.e. potential energy in Mechanical Engineering Concepts in Kenya is independent of the previous history because the gravitational force is conservative. A force is said to be conservative if the work done by the force from a point A to B depends only on the position vectors rA and rB. in particular, a conservative force must not depend on time, or on the velocity or acceleration of the body.
Conclusion of Mechanical Engineering Concepts in Kenya
From the knowledge of the law of conservation of energy in Mechanical Engineering Concepts in Kenya, it is obvious that energy is always conserved; it can be transformed thou.
The product of a force and the displacement from its original position is called work. If one is pushing a heavy block across a room, then the further one moves, the more the work one does in Mechanical Engineering Concepts in Kenya. | <urn:uuid:ad8c3327-8720-416f-ac8d-ce20d2d2df60> | 3.53125 | 777 | Knowledge Article | Science & Tech. | 43.512555 | 95,523,109 |
The National Aeronautics and Space Administration has initiated a major effort to establish a permanent manned presence in space to expand the exploration and use of space for activities that enhance the security and welfare of mankind. In particular, Space Station would:
- Establish a means for the permanent presence of people in space.o Provide a capability for routine, continuous utilization of space for science, applications, technology development, commercial utilization, national security and general operations. - Lead to the development and exploitation of the synergistic effects of the man/machine combination in space. - Provide for essential system elements and operational practices for an integrated national space capability. - Reduce the cost and complexity of living in and using space. | <urn:uuid:d0fcb919-cc01-41c3-b68b-a692190be1df> | 3.3125 | 141 | Knowledge Article | Science & Tech. | 0.488654 | 95,523,143 |
Posts Tagged ‘gulf bp horizon’
Hungry for a solution to our world’s environmental problems? So are a number of organisms that scientists are hoping will some day be used to mitigate oil spills, lessen the effects of climate change, break down plastics, and provide alternative fuel sources. By harnessing the power of the all-powerful appetite, researchers hope to find creatures that will make a meal out of our wastes and transform them into something less toxic and perhaps even beneficial.
·Fungal Food: Researchers from Yale found a new species of fungus in the Amazon, Pestalotiopsis microspora, that feeds on polyurethane in oxygen-free environments. Now, the ubiquitous and nearly indestructible plastics that were once sure to persist for generations may now be able to be digested in landfills and other controlled environments.
·Gribble Guts: The digestive tract of a small wood-munching crustacean may hold the key to a new source of biofuel. The gribble, a notorious diner of fishing boats and ocean-side piers, produces a set of enzymes to help break down plant matter instead of relying on bacteria like most other organisms. These chemicals could help covert cellulose into simple sugars that could then be fermented and used to power cars.
·Have You Herd: Moose, reindeer and other grazers may help to help cool warming areas of the tundra in Siberia. By keeping grass healthy and trampling snow, these browsers help to maintain the permafrost and sustain the plants that reflect sunlight and trap greenhouse gasses. Repopulating land with the animals not only results in a short term temperature drop, but by mitigating the effects of climate change, could also contribute to a more long term adjustment in the weather.
·Micro-Managing: Scientists at the Lawrence Berkeley National Laboratory have discovered oil-digesting bacteria in the waters of the Gulf in the wake of the BP Horizon spill. These microbes seem to love hydrocarbons and are able to break down many of the compounds found in crude oil in a short amount of time. Some would like to culture and spray these bacteria over the Gulf in order to take care of the remains of the disaster. However, while the debate continues as to how effective the bacteria would be, they are certainly becoming a topic of great interest for those looking for a biologically centered cleanup solution. | <urn:uuid:b601f2b7-b198-4b97-bc83-850ab8b3ecde> | 2.71875 | 498 | Content Listing | Science & Tech. | 33.860321 | 95,523,163 |
Acacia working in tandem with fire is severely degrading the Kerangas (heath) forests of Brunei reports James Margrove, a research intern from University of Aberdeen, UK working with the Institute for Biodiversity and Environmental Research (IBER) at UBD.
Kerangas forest occurs throughout Borneo on raised beaches and is known for its inability to support agriculture: the word Kerangas is an Iban word that roughly translates as ‘land which cannot grow rice’. These forests have not evolved to withstand burning and so recovery after fires takes decades. Acacias belong to a family of exotic trees native to Australia. Their adaptive ecology to fire allows Acacia to dominate these disturbed environments, and there is a fear that this will prevent native Kerangas’ subsequent recovery.
After completing his Masters of Biological Sciences specialising in tropical forest ecology at the University of Aberdeen, James jumped at the opportunity to extend his studies into Kerangas forests, and embarked on a 6 month field based project to investigate how Brunei’s forests are being changed by Acacia and fire. He is collaborating with Dr Rahayu Sukri and Assoc Prof Dr Kushan Tennakoon of the Faculty of Science and IBER at UBD, and Prof David Burslem of the School of Biological Sciences, University of Aberdeen in the UK. Prof Burslem visited UBD for the second time on 8th January 2014 to continue work with the team. This particular project work is being supported by a research grant from UBD while James’ visit is funded by the British High Commission in Brunei.
Acacia is prized for its quick growth and production of useful timber for furniture, making it a great choice for forestry plantations and stabilising soil after anthropogenic or natural disturbances. As a result, Acacia has been planted in environments around the globe, from Mediterranean climates in South Africa to tropical Southeast Asia. However, due to its vigorous growth, Acacia can become an invasive pest, outcompeting native flora and putting pressure on native ecosystems. Here in Brunei, observations suggest that Acacia, assisted by fire, is spreading and will ultimately severely degrade the forest’s biodiversity, as well as preventing regeneration of native Kerangas plant species.
The current project investigates the impact of invasive Acacia in conjunction with fire on the Kerangas forest of Brunei. The research group is looking at changes in edaphic conditions, species compositions and light environments in localities that were formally pristine Kerangas forest. No studies as yet have investigated changes in these characteristics, and the team hope that the results will provide a solid foundation for a more comprehensive assessment of Acacia invasion in Brunei Darussalam, as well as the research and development of restorative measures.
Universiti Brunei Darussalam (UBD) continues on its upward path, rising three places to 34 in the QS
Universiti Brunei Darussalam (UBD) achieved another major milestone. It leapt up the Quacquarelli Sy
Universiti Brunei Darussalam (UBD) received a donation of paintings and portraits from Hongkong Shan
DiscoverUBD is a quarterly university newsletter featuring news, events and articles on research and conferences that have been held in the university | <urn:uuid:7a6a8f40-f44c-4f67-bc52-85b84f0a1ab9> | 2.84375 | 677 | News (Org.) | Science & Tech. | 11.332059 | 95,523,176 |
|Named after||Charles-Adolphe Wurtz|
|Reaction type||Coupling reaction|
|Organic Chemistry Portal|
|RSC ontology ID|
The Wurtz reaction, named after Charles-Adolphe Wurtz, is a coupling reaction in organic chemistry, organometallic chemistry and recently inorganic main group polymers, whereby two alkyl halides are reacted with sodium metal in dry ether solution to form a higher alkane:
- 2R–X + 2Na → R–R + 2Na+X−
Other metals have also been used to effect the Wurtz coupling, among them silver, zinc, iron, activated copper, indium and a mixture of manganese and copper chloride. The related reaction dealing with aryl halides is called the Wurtz-Fittig reaction.This can be explained by the formation of free radical intermediate and its subsequent disproportionation to give alkene. The Wurtz reaction occurs through a free radical mechanism.
The reaction consists of a halogen-metal exchange involving the radical species R• (in a similar fashion to the formation of a Grignard reagent) with carbon–carbon bond formation occurring in a nucleophilic substitution reaction.
One electron from the metal is transferred to the halogen to produce a metal halide and an alkyl radical.
- R–X + M → R• + M+X−
The alkyl radical then accepts an electron from another metal atom to form an alkyl anion. This intermediate has been isolated in several cases.
- R• + M → R−M+
The nucleophilic carbon of the alkyl anion then displaces the halide in an SN2 reaction, forming a new carbon-carbon covalent bond.
- R−M+ + R–X → R–R + M+X−
Examples and reaction conditions
Due to several limitations this reaction is seldom used. For example, it is intolerant of a range of functional groups. Wurtz coupling is, however, useful in closing small, especially three-membered, rings. Bicyclobutane was prepared this way from 1-bromo-3-chlorocyclobutane in 95% yield. The reaction is conducted in refluxing dioxane, at which temperature, the sodium is liquid. This reaction has poor yield which is a consequence of multiple product formation. In the case of (1,3), (1,4), (1,5), (1,6) dihalides, it leads to formation of cyclic products. In vicinal dihalides, it forms alkenes whereas in geminal dihalides, it forms alkynes.
The Wurtz reaction is limited to the synthesis of symmetric alkanes. If two dissimilar alkyl halides are taken as reactants, then the product is a mixture of alkanes that is often difficult to separate by fractional distillation as the differences between the boiling points of the products is typically very low. Also, since the reaction involves free radical species, a side reaction occurs to produce an alkene. This side-reaction becomes more significant when the alkyl halides are bulky at the halogen-attached carbon. Methane can not be obtained by this method. The reaction fails in case of tertiary halides.
- Adolphe Wurtz (1855). "Sur une nouvelle classe de radicaux organiques". Annales de chimie et de physique. 44: 275–312.
- Adolphe Wurtz (1855). "Ueber eine neue Klasse organischer Radicale". Annalen der Chemie und Pharmacie. 96 (3): 364–375. doi:10.1002/jlac.18550960310.
- Organic Chemistry, by Morrison and Boyd
- Organic Chemistry, by Graham Solomons and Craig Fryhle, Wiley Publications | <urn:uuid:6a0cad07-4ae0-4d53-b1b4-f26c4aa88cd9> | 2.984375 | 843 | Knowledge Article | Science & Tech. | 43.944619 | 95,523,180 |
The largest study of “jumping genes” ever conducted has found genes frequently move between distantly related species, and this inheritance probably played a large role in mammals’ evolution. Technically known as transposable elements, these genes have been found to move not only among animals, but between plants and animals. Be nice to trees, you’ve more in common than you might think.
Transposable elements are segments of DNA that can insert themselves in different locations in the genome. They often do this multiple times, so that the same stretch of DNA code can appear in multiple places. Once a jumping gene gets into the germline it becomes an ongoing part of a species.
Dr Atma Ivancevic of the University of Adelaide is the lead author of a record-breaking study of the jumping genes L1 and BovB in 759 species of plants, animals, and fungi. She found the genes were much more widespread than anticipated. However, their absence from some species allowed Ivancevic to prove the genes reached the genomes of many animals through “horizontal transfer”, rather than by being inherited from a common ancestor as previously thought.
For example, L1, which appears to cause some cancers and neurological diseases, is absent from the platypus and echidna, demonstrating the gene wasn’t present in the first mammals. On the other hand, forms of L1 turn up in everything from plants to amphibians, indicating it could not have spontaneously appeared among mammals after the monotremes separated from marsupials and placental mammals.
“We don’t really know where the L1 gene comes from originally. We thought it might be frogs, but can’t confirm. We do know the versions in reptiles and plants look a lot older than those in mammals,” Ivancevic told IFLScience.
Exactly how L1 moves between species is unclear, although Ivancevic thinks there are multiple pathways. Similar versions exist in bats and frogs, and she thinks when bats prey on the frogs they may acquire DNA in the process.
In other cases, insects are likely vectors. In Genome Biology Ivancevic pointed to ticks as the probable culprits in transferring BovB genes between species. She told IFLScience sometimes vector species pass DNA on without incorporating it in their own genome, while other vectors can have DNA filled with these jumping genes.
Transposable elements aren’t some rare curiosity; they take up a quarter of the genome of cows and sheep.
Ivancevic explained L1 causes instability in genome regulatory structures, and its presence may help explain the different rates of species formation between monotremes and other mammals.
“We think the entry of L1s into the mammalian genome was a key driver of the rapid evolution of mammals over the past 100 million years,” said senior author Professor David Adelson in a statement. | <urn:uuid:ed193c5d-1a3e-4c28-b727-fab10fd66dd1> | 3.90625 | 603 | News Article | Science & Tech. | 37.653772 | 95,523,207 |
Eugène-Melchior Péligot (24 March 1811, Paris – 15 April 1890, Paris), also known as Eugène Péligot, was a French chemist who isolated the first sample of uranium metal in 1841.
Péligot proved that the black powder of Martin Heinrich Klaproth was not a pure metal (it was an oxide of uranium, known in chemistry as UO2). He then succeeded in producing pure uranium metal by reducing uranium tetrachloride (UCl4) with potassium metal. Today better methods have been found.
Péligot's salt is also named after him.
Péligot was a professor of analytical chemistry at the Institut National Agronomique. He collaborated with Jean-Baptiste Dumas, and together they discovered the methyl radical during experiments on wood spirit (methanol). The terminology "methyl alcohol" was created by both chemists from "wood wine". They also prepared the gaseous dimethyl ether, and many esters. In 1838, they successfully transformed camphor into p-cymene using phosphorus pentoxide.
In 1844 he synthesized chromium(II) acetate, which was much later recognized (by F. Albert Cotton in 1964) to be the first chemical compound which contains a quadruple bond. | <urn:uuid:af7674e4-d21d-4d49-b066-ed2a78a96571> | 3.4375 | 280 | Knowledge Article | Science & Tech. | 41.68 | 95,523,209 |
Initial impressions using VIPER Architecture in iOS development
Some traditional iOS developers use MVC architecture for long years without try other approaches. The MVC organizes the code, grouping them in one of the three layers (Model, View or Controller). But when we are working in some big projects we need more than three layers to get a better code organization.
The problem of using the plain MVC is the Controller classes handle a lot of work as we see below:
MVC - Model
- contains entities objects;
- handles persistence of the each entities;
- handles the business logic.
MVC - Controller
- intermediate View and Model objects;
- handles the views and application logic;
- tests View logics, data transformation, basic validations;
- manage Keyboard, tableView delegate and datasource;
- handles navigation between views;
- manages and takes part in the responder chain used to handle events.
MVC - View
- draw and animate the interface;
- handle the user interaction passing data to Controllers.
Note the Controller responsibility. It explains why developers use too manny #pragma mark to organize their codes. If your controller classes are huge, you have fallen into Massive View Controller problem.
Ok, what can be done now? Searching in the web, there are some articles about another architecture called VIPER.
A brief introduction about VIPER
Viper is an acronym for View, Interactor, Presenter, Entity, and Routing. It has the following functionalities:
Viper - View
- they are dummy views;
- contain objects like UIView, UIViewController, UILabel, etc;
- waits the content from the Presenter;
- handle user interaction and pass it to Presenter layer.
Viper - Presenter
- doesn’t know UI objects;
- get inputs from View layer;
- handle the view logic (add method will present other screen);
Viper - Routing
- handle the navigation logic and transition animations;
- knows objects like UINavigationController, UIWindow, etc;
Viper - Interactor
- handle the business rules described as use case;
- translate data between Entity and Presenter layers;
Viper - Entity
- represent business objects;
- are simple data structures manipulated by Interactor;
Translate the MVC to VIPER is a split task where each layer will lose some weights. See below how objects will move between both architecture:
There are some critics I noted after build my first project with VIPER definitions.
First, Interactor objects represent one single use case. Sometimes it will be so small that it will increase the number of objects in your project;
Second, Storyboard Segues will conflict with Routing layer;
I think it's ok to use Storyboard Segues to represent the static routing in your application. Wireframes will be useful to turn it dynamic!
Finally, basic configurations already setted in the Storyboard need to be recreated in Wireframes objects.
It's clear that MVC is overdate to real projects and maybe it will lead you to maintain huges Controller classes. VIPER, in the other way, solve it adding more layers with clear objectives. It will costs a little bit more code to turn off some storyboard features but it's worth. | <urn:uuid:e2498103-d578-4e79-9ef7-2fe7d54de684> | 3.015625 | 701 | Personal Blog | Software Dev. | 30.217629 | 95,523,250 |
The study of benthic organism is necessary to obtain a comprehensive idea of the fishery potential of any biotope. Benthic research in sedimentary estuarine environments began with an emphasis on descriptions of organism distributions and abundance. The present study area extends over distance of about 35 km and bound between Poompukar in the north and Nagore in the South India. The present study focuses on determining the spatial distribution and structure of the benthic assemblages, and to evaluate the species diversity along the study area, and finally whether there is any impact of black sand distribution on the benthic and pelagic community. A survey of benthic macrofauna at a total of 12 sampling stations from Poompukar to Nagoor was carried out between November 2004 to March 2005. Positions were fixed with a Trimble Global Positioning System (GPS). The sampling stations were chosen to quantify the benthos both within the black sand enrichment areas. The black sand enrichment area like Chandrapadi, Karaikal and Nagoor indicates that the colonisation of macrobenthic fauna is totally absent. This study is carried out on benthos in terms of impact of beach sand extraction and concluded that the white sand constituted more habitats than the black sand area. The sediment grain size particularly in coarse sand having non-black sand shows more interrelationship with macrobenthic faunal diversity which also clearly indicate the supply of organic matter source of food web to the species. | <urn:uuid:3fc2723c-a69b-4f78-8999-7f6876e12ac5> | 2.796875 | 306 | Knowledge Article | Science & Tech. | 25.359247 | 95,523,266 |
If you walk into a cloud at the top of a mountain with a cup to slake your thirst, it might take a while for your cup to fill. The tiny, barely-there droplets are difficult to see, and for scientists they, along with rain and snow, are among the hardest variables to measure in Earth Science, says Ana Barros, professor of engineering at Duke University. As part of the Science Team for NASA's Precipitation Measurement Missions (PMM) that measure rainfall from space, Barros and her research team trekked into the Great Smoky Mountains and other areas of the southern Appalachian Mountains, to learn more about where, when and how rain falls in the rugged terrain. What they found was eye-opening: much of the water people counted on falls as light rain, and no one knew about it.
Mid-morning peak in light rainfall appears as clouds and fog at Purchase Knob in the Great Smoky Mountains National Park. Light rainfall is the most reliable and most frequent form of rainfall in the region, contributing 50 to 60 percent of the total precipitation over a year. Light rain is no less than the lifeline of freshwater resources for the landscape’s ecosystems. Credit: NASA/Barros
Understanding precipitation in the mountains is one of the first steps to understanding local ecology, regional climate, and the effects of any changes that might impact the nearly 30 million people in Georgia, South and North Carolina, and Tennessee whose water supply comes from southern Appalachian headwaters. To answer some of these big questions, scientists are increasingly turning to satellite data.
Barros describes satellite-based precipitation instruments as a game changer for scientists in how they study hydrology and do science. NASA's Tropical Rainfall Measuring Mission (TRMM), launched in 1997, and the upcoming Global Precipitation Measurement (GPM) mission that will launch in February 2014, see more of Earth than ground-based instruments and from a vantage point that is not impeded by topography in mountainous regions. TRMM takes multiple measurements—at different times of day—to give researchers improved observations of weather systems. But how accurate is the data they deliver?
While Barros and her team were sticking sensors on mountaintops, they were also downloading data from TRMM's precipitation measurement instruments and data processing products. The dual collection of data from the ground and the sky allows scientists like Barros to validate and improve those satellite measurements, and make a few discoveries along the way.
They're Called the Smokies, But It's Not What You Think
Prior to Barros's work, which began in 2007, ground based rainfall stations for weather forecasting and climate monitoring in the southern Appalachians were few and far between. Ten rain gauges were located at elevations above 3,280 feet (1,000 meters) to monitor an area of roughly 28,957 square miles (75,000 square kilometers). Little information was available on what was truly happening with water falling as precipitation in remote places, in high places—places no one would call easily accessible.
Enter the research team. Bushwhacking up mountains, suffering stings from angry bees, and walking where 3,000 bears run wild, Barros and her team installed a network of 32 science-grade rain gauge stations between the summers of 2007 and 2009. The stations, all above 3,280 feet (1,000 meters), dotted seven range-following linear ridges that cut across the east-west span of the southern Appalachian Mountains, from North Carolina to Tennessee. The study area covered 540 square miles (1,400 square kilometers), including the Great Smoky Mountains National Park in the Pigeon River Basin.
The team also measured conditions in the atmospheric column at each location. Balloons—either tethered to the ground or free flying—carried sensors into the clouds. Two mobile MicroRain Radars, which the team moved from station to station, enabled the scientists to estimate the vertical distribution of rainfall. At some stations, local wifi sent the radar data over the Internet in real time, but more often, the researchers had to make the long slog to the rain gauge stations to ensure sensors and data were in good order, and to evaluate data coming from the satellites. During intense field observing campaigns, the team had to get friendly with solitude and roughing it in the outdoors.Who'll Start the Rain?
Most people don't realize, Barros says, the southern Appalachians have the highest annual rainfall of the southeastern United States, as much as humid Florida. It rains on average 54 inches per year in the Everglades, about 50 inches in North Carolina, and about 58 to 60 inches a year in the Appalachians. The Mountains contribute to the enhanced weather: moist air bumps into them as it moves over the land, and when it rises, it cools and can't hold on to its water vapor which condensates and forms clouds. This leads to as much rain falling in the Appalachians as is delivered to the coast by hurricanes like Francis or Ivan. And in years without a hurricane or tropical storm to factor in, it rains nearly the same amount, on average, every month in the southern Appalachians. Forty percent in summer and up to 60 to 70 percent in winter of all that rainfall is very light rainfall.
That's why the Smokies are called the Smokies, Dr. Barros explains. "There's always a little bit of fog and low level clouds and there's always a little bit of rain going on in the air." Until her team measured it, scientists didn't know how important light rain is to the region. At all times of the day, light rainfall is the dominant type of precipitation. And because light rainfall is the most reliable and most frequent form of rainfall in the region, Barros says, contributing 50 to 60 percent of total precipitation over a year, it governs the regional water cycle. Light rain is no less than the lifeline of freshwater resources for the landscape's ecosystems. This is probably also true in mountainous regions everywhere, Barros' finds, which carries big implications for communities worldwide.
If you're a forest, an ecosystem, an animal, a person, or an urban community—namely everything and everyone—you can receive the amount of water you need for the year super fast. A fifteen-minute blast from heavy rainfall might give you your total water budget, torrents of water rushing over the ground, heading into channels, stream networks and rivers. Or you might receive your water slowly, spread out over a couple of months as light rainfall, a mist that gently settles. At the end of the year, you can have the same amount of water, just over different spans of time, and that affects where the water goes. If it falls fast, in a short span of time, water won't linger on the ground. If it falls slowly, and persistently, moisture from light rain can infiltrate soil layers, percolate deeper, and recharge underground aquifers.
Will Light Rain Become a Misty Memory?
So what happens to light rain as global climate shifts, and things grow warmer? At lower elevations, more of the fine drops from light rain will evaporate in the air and fail to reach the ground. Lower elevations will have to contend with not only higher temperatures, but less cloud cover—affecting a cycle in which plants and forests and rain have this amazing rhythm in which one feeds the other (see sidebar). Depending on how daytime temperatures change, Barros' thinks that morning light rainfall would likely be more sustainable than afternoon light rainfall.
There you have the set up for huge impacts, some of which are already making the news. As Barros explains, most of the states in the region have some sort of lawsuit against each other because of access to water resources. Georgia, North Carolina and South Carolina share aquifers. "In North Carolina," Dr. Barros says, "different stakeholders are suing each other regarding inter-basin water transfers because of the high frequency of drought we're having. So this dependency on light rainfall can be more critical than all the big floods and all the big disasters we're talking about in terms of sustainability, in terms of long-term environmental quality."
How things shape up bears further study, but one thing that is critical to future water resource planning is knowing where and how and when those resources are coming, and how much they are changing. Barros and others' work to improve satellite measurements, especially for the Global Precipitation Measurement mission that will have increased sensitivity to detect light rain, are the first step to a better understanding of the regional water cycle. By knowing how large a role light rain plays in the water budget of the southern Appalachian region, people can plan for future changes in nature's water delivery system.For more information about the TRMM and GPM missions:
Ellen Gray | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
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Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
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Two Johns Hopkins neuroscientists have discovered the “molecular brakes” that time the generation of important cells in the inner ear cochleas of mice. These “hair cells” translate sound waves into electrical signals that are carried to the brain and are interpreted as sounds. If the arrangement of the cells is disordered, hearing is impaired. A summary of the research will be published in The Journal of Neuroscience on Sept. 16.
“The proteins Hey1 and Hey2 act as brakes to prevent hair cell generation until the time is right,” says Angelika Doetzlhofer, Ph.D., an assistant professor of neuroscience. “Without them, the hair cells end up disorganized and dysfunctional.”
The hair cells of mice missing just Hey2 are neatly lined up in four rows (left) while those missing Hey1 and Hey2 are disorganized (right). The cells' hairlike protrusions (pink) can be misoriented, too.
The cochlea is a coiled, fluid-filled structure bordered by a flexible membrane that vibrates when sound waves hit it. This vibration is passed through the fluid in the cochlea and sensed by specialized hair cells that line the tissue in four precise rows. Their name comes from the cells’ hairlike protrusions that detect movement of the cochlear fluid and create electrical signals that relay the sound to the brain.
During development, “parent cells” within the cochlea gradually differentiate into hair cells in a precise sequence, starting with the cells at the base of the cochlea and progressing toward its tip. The signaling protein Sonic Hedgehog was known to be released by nearby nerve cells in a time- and space-dependent pattern that matches that of hair cell differentiation. But the mechanism of Sonic Hedgehog’s action was unclear.
Doetzlhofer and postdoctoral fellow Ana Benito Gonzalez bred mice whose inner ear cells were missing Hey1 and Hey2, two genes known to be active in the parent cells but turned off in hair cells. They found that, without those genes, the cells were generated too early and were abnormally patterned: Rows of hair cells were either too many or too few, and their hairlike protrusions were often deformed and pointing in the wrong direction.
“While these mice didn’t live long enough for us to test their hearing, we know from other studies that mice with disorganized hair cell patterns have serious hearing problems,” says Doetzlhofer.
Further experiments demonstrated the role of Sonic Hedgehog in regulating the two key genes.
“Hey1 and Hey2 stop the parent cells from turning into hair cells until the time is right,” explains Doetzlhofer. “Sonic Hedgehog applies those ‘brakes,’ then slowly releases pressure on them as the cochlea develops. If the brakes stop working, the hair cells are generated too early and end up misaligned.”
She adds that Sonic Hedgehog, Hey1 and Hey2 are found in many other parent cell types throughout the developing nervous system and may play similar roles in timing the generation of other cell types.
This work was supported by grants from the Whitehall Foundation (2010-05-81) and the National Institute on Deafness and other Communication Disorders (F32DC013477, DC005211).
On the Web:
View the article at The Journal of Neuroscience (after the embargo lifts). http://dx.doi.org/10.1523/JNEUROSCI.1494-14.2014
Catherine Kolf | newswise
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:ea77e35e-c263-4348-b183-43637e1807f0> | 3.859375 | 1,353 | Content Listing | Science & Tech. | 45.082863 | 95,523,282 |
Dispersal, Habitat disturbance and persistence, Life history strategy, Planthopper, Prokelisia marginata, Prokelisia dolus, Salt marsh, Spartina, Wing olymorphism.
Dispersal is considered a vital life history characteristic for insects exploiting temporary habitats, and life history theorists have often hypothesized an inverse relationship between dispersal capability and habitat persistence. Most often, this hypothesis has been tested using interspecific comparisons of dispersal capability and qualitative estimates of habitat persistence. Consequently, most assessments have failed to control for possible phylogenetic nonindependence and they also lack quantitative rigor.
We capitalized on existing intraspecific variation on the dispersal capability of Prokelisia planthoppers to examine the relationship between habitat persistence and dispersal, thereby minimizing possible phylogenetic effects. Two congeneric species (Prokelisia marginata and P. dolus) occur in the intertidal marshes of North America, where they feed exclusively on cordgrasses (Spartina). Because these planthoppers exhibit wing dimorphism, flight-capable adults (macropters with fully developed wings). Thus, dispersal capability can be readily estimated by the percentage of macropters in a population.
At a regional spatial scale, we found a highly significant negative relationship between dispersal capability (present macroptery) and habitat persistence. In this system, habitat persistence is influenced by a combination of marsh elevation, winter severity, and tidal range, which interact to determine the ability of planthoppers to endure through winter in their primary habitat for development. P. marginata develops primarily in low-marsh habitats during summer, habitats that can be subjected to pronounced winter disturbance due to ice scouring and/or extensive tidal inundation. Levels of winter disturbance of the low marsh are extreme along the Atlantic coast, intermediate along the Pacific, and low along the Gulf. Both the failure of P. marginata populations to remain through winter in the habitat, and the dispersal ability of these populations (92%, 29%, and 17% macroptery, respectively), are correlated with levels of disturbance. Thus, in regions where winter disturbance is high, levels of dispersal are correspondingly high to allow for recolonization of extirpated habitats from overwintering sites on the high marsh. Unlike P. marginata, P. dolus develops primarily in high-marsh habitats, which are much less disturbed on all coasts during winter. Consequently, this species remains year-round in its primary habitat for development, and most populations exhibit relatively low levels of macroptery (<10%).
When raised under common garden conditions, many more macropters of both species were produced from Atlantic compared to Gulf populations. Thus the proportion of macropters produced from the populations used in this experiment paralleled the incidence of macroptery measured in the field, providing evidence that the geographic variation in dispersal capability in both species has in part a genetic basis. The results of this study provide strong intraspecific evidence for an inverse relationship between the dispersal capability of insects and the persistence of their habitats.
Required Publisher's Statement
Copyright by the Ecological Society of America
Denno, R.F., Roderick, G.K., Peterson, M.A., Huberty, A.F., Döbel, H.G., Eubanks, M.D., Losey, J.E., and G.A. Langellotto. 1996. Habitat Persistence Underlies Intraspecific Variation in the Dispersal Strategies of Planthoppers.
Courtesy of JSTOR
Stable URL: http://www.jstor.org/stable/2963487
Denno, Robert F.; Roderick, George K.; Peterson, Merrill A.; Huberty, Andrea F.; Dobel, Hartmut G.; Eubanks, Micky D.; Losey, John E.; and Longellotto, Gail A., "Habitat Persistence Underlies Intraspecific Variation in the Dispersal Strategies of Planthoppers" (1996). Biology. 45. | <urn:uuid:79b7f172-4996-4aef-9704-a5ababb9abd7> | 3.203125 | 855 | Academic Writing | Science & Tech. | 16.145629 | 95,523,308 |
A computational model developed by scientists at the Salk Institute for Biological Studies now suggests that newborn brain cells—generated by the thousands each day—add a time-related code, which is unique to memories formed around the same time.
“By labeling contemporary events as similar, new neurons allow us to recall events from a certain period,” speculates Fred H. Gage, Ph.D., a professor in the Laboratory for Genetics, who led the study published in the Jan. 29, 2009, issue of the journal Neuron. Unlike the kind of time stamp found on digital photographs, however, the neuronal time code only provides relative time.
Ironically, Gage and his team had not set out to explain how the brain stores temporal information. Instead they were interested in why adult brains continually spawn new brain cells in the dentate gyrus, the entryway to the hippocampus. The hippocampus, a small seahorse-shaped area of the brain, distributes memory to appropriate storage sections in the brain after readying the information for efficient recall.
“At least one percent of all cells in the dentate gyrus are immature at any given time,” explains lead author Brad Aimone, a graduate student in the Computational Neuroscience Program at the University of California, San Diego. “Intuitively we feel that those new brain cells have to be good for something, but nobody really knows what it is.”
Each of these newborn neurons undergoes a prolonged maturation process, during which it changes from hyper-excitable to composed and reaches out to mature brain cells that are already well-connected within the established circuitry. Exercise, learning, and environmental enrichment increase proliferation and survival of new neurons, while pathological (chronic) stress and age send their numbers plummeting. Despite an increasing understanding of how new neurons become part of the existing dentate gyrus network, it is still unclear what their exact function is.
Trying to ascertain the newcomers’ job in adult brains, the Salk researchers took every piece of available biological information and fed it into a computer program designed to simulate the neuronal circuits in the dentate gyrus. “Most modelers test a specific hypothesis and build a model around it,” says Aimone. “We tried not to make any big assumptions about the function of new neurons. Instead we asked, ‘What is the biology, and what does the math suggest?’”
It quickly became clear that overly excitable youngsters respond indiscriminately to incoming information. “The circuit in the dentate gyrus is designed to separate incoming memories into distinct events, a process called pattern separation, but immature cells get into the way by blurring the lines,” says Aimone. “And if they keep muddling the picture, there’s almost no point.”
But nothing lasts forever. Even the most highly strung nerve cells that used to get excited by just about anything will eventually quiet down. As they mature into fully functional granule cells, they take their place in the existing circuitry while the next generation of newborn neurons takes their place firing away at new events.
Yet, independent events that had nothing in common but the fact that they occurred around the same time will now be connected forever in our minds—explaining why discussing the movie we saw a couple of months ago might bring back the name of the café we visited afterward but whose name has been eluding us.
“Current thinking holds that when we bring up a certain memory, it passes back to the dentate gyrus, which pulls all related bits of information from their offsite storage,” says Gage. “Our hypothesis suggests that cells that were easily excitable bystanders when the memory was formed are engaged as well, providing a hyperlink between all events that happened during their hyperactive youth.”
The study was funded by the James S. McDonell Foundation, the Kavli Institute for Brain and Mind, the NSF Temporal Dynamics of Learning Center, and the U.S. National Institutes of Health.
Janet Wiles, Ph.D, a professor at the School of Information Technology and Electrical Engineering, University of Brisbane, Australia, also contributed to the study.
The Salk Institute for Biological Studies in La Jolla, California, is an independent nonprofit organization dedicated to fundamental discoveries in the life sciences, the improvement of human health, and the training of future generations of researchers. Jonas Salk, M.D., whose polio vaccine all but eradicated the crippling disease poliomyelitis in 1955, opened the Institute in 1965 with a gift of land from the City of San Diego and the financial support of the March of Dimes.
Gina Kirchweger | Newswise Science News
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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The yield of DNA double-strand breaks (DSBs) in SV40 DNA irradiated in aqueous solution was found to increase by more than a factor of two as a result of postirradiation incubation of the DNA at 50 degrees C and pH 8.0 for 24 h. This is in agreement with data from studies performed at 37 degrees C that were published previously. Importantly, similar results were also obtained from irradiation of mammalian DNA in agarose plugs. These results suggest that heat-labile sites within locally multiply damaged sites are produced by radiation and are subsequently transformed into DSBs. Since incubation at 50 degrees C is typically employed for lysis of cells in commonly used pulsed-field gel assays for detection of DSBs in mammalian cells, the possibility that heat-labile sites are present in irradiated cells was also studied. An increase in the apparent number of DSBs as a function of lysis time at 50 degrees C was found with kinetics that was similar to that for irradiated DNA, although the magnitude of the increase was smaller. This suggests that heat-labile sites are also formed in the cell. If this is the case, a proportion of DSBs measured by the pulsed-field gel assays may occur during the lysis step and may not be present in the cell as breaks but as heat-labile sites. It is suggested that such sites consist mainly of heat-labile sugar lesions within locally multiply damaged sites. Comparing rejoining of DSBs measured with short and long lysis procedure indicates that the heat-labile sites are repaired with fast kinetics in comparison with repair of the bulk of DSBs.
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These differ in part considerably from the propagation strategies of endemic plant species. Dr. Ingolf Kühn and Dr. Sonja Knapp of the Helmholtz Centre for Environmental Research (UFZ) reached this conclusion in a study published in the current issue of the scientific journal Ecology Letters.
"These results are an argument in support of the view that the need to differentiate between native and non-native species in ecological systems remains", says Dr. Ingolf Kühn.
Experts are currently debating whether this differentiation might be untenable, as it is only a question of the extent to which a plant species - regardless of its origin - is able to adapt to man-made conditions (Davis et al. (2011), Nature; Thompson et al. (2011) Trends in Ecology & Evolution). In the professional journal Trends in Ecology & Evolution (van Kleunen et al. (2011), Hulme et al. (2011)) a number of research groups counter with the argument that differentiating between these two groups contributes essentially to the understanding of modern ecosystems, as endemic and non-native species differ in many respects.
In their current study the UFZ researchers Dr. Ingolf Kühn and Dr. Sonja Knapp investigated this thesis and examined the question, whether the factors influencing the frequency of occurrence of non-native plant species are different from those for native species. Their investigations made use of the BiolFlor biological-ecologic data base for the characteristic features of flora in Germany, with more than 3,600 native and also established introduced species of ferns and flowering plants. They compared such features as life span, pollinating strategy and the occupation of different habitats and relate these features to the frequency of occurrence of a particular species.
Their results show that the frequency of occurrence of the introduced plant species is in fact influenced by other strategies than the frequency of occurrence of native species. "The introduced species profit in particular from the fact that they blossom later in the year. The flowering time is, on the other hand, not a relevant feature for the frequency of occurrence of native species", says Dr. Sonja Knapp. A number of the most common introduced plant species seek a time niche between October and December, during which most of the native competitors no longer blossom. The remaining pollinators, such as bees, bumble bees and certain other insects, then pollinate only these plants. If there are no longer sufficient pollinators during this time, many of the introduced plants, such as asters and other composite flowers, can undergo self-pollination and in this manner ensure their survival.
For many native species an advantageous strategy is to become well established in many different habitats, such as in forested areas and simultaneously in meadows. "On the other hand, for non-native species this appears to be less important. They do not need to occupy as many different habitats as the native species in order to achieve the same frequency of occurrence", says Dr. Sonja Knapp. The introduced plant species are so successful in the few habitats in which they occur that widespread adaptation is no longer necessary. This is probably related to the origin of many non-native plants in Germany: The successfully introduced species are above all species which have adapted to an agricultural environment, which accompany seeds or have the character of field herbs, or species able to adapt to disturbances such as found in urban habitats, and which therefore have good possibilities for spreading over large areas.
Non-native plant species are, initially, in competition with the native species. It is therefore understandable that newly arrived plants occupy niches not completely used by native species. Consequently, such non-native species frequently make use of these niches. Most introduced species pose no serious threats to our ecosystems. Around one per cent of the introduced species are, however, invasive. This means that their spread is so significant that they suppress native plants and disturb the ecosystem.The UFZ researchers therefore believe that the differentiation between native and non-native plant species remains correct and important, even when they have been established in Germany for many centuries. Dr. Ingolf Kühn: "On the evolutionary time scale 500 years are a mere blinking of an eye. And because native and introduced species in fact exhibit differences in certain features, they should not all be considered together. Especially the importance of the early recognition of possible dangers due to the presence of introduced species requires knowledge of their origin."
The investigations were supported by the the Helmholtz Association (core subject ‘Land Use Options and Biodiversity').Additional scientific information:
http://www.ufz.de/index.php?en=21942At the Helmholtz Centre for Environmental Research (UFZ) scientists are researching the causes and consequences of far-reaching changes to the environment. They are concerned with water resources, biological diversity, the consequences of climate change and adaptability, environmental and biotechnologies, bioenergy, the behaviour of chemicals in the environment, their effect on health, modelling and social science issues. Their guiding theme: Our research contributes to the sustainable use of natural resources and helps to secure this basis for life over the long term under the effects of global change. The UFZ employs 1,000 people in Leipzig, Halle and Magdeburg. It is financed by the federal government and the federal states of Saxony and Saxony-Anhalt.
http://www.ufz.de/The Helmholtz Association contributes towards solving major and pressing social, scientific and economic issues with scientific excellence in six research areas: Energy, Earth and Environment, Health, Key Technologies, Structure of Matter, Aeronautics, Aerospace and Transport. The Helmholtz Association is Germany's largest scientific organisation with over 33,000 employees in 18 research centres and an annual budget of approximately 3.4 billion euros. Its work stands in the tradition of the naturalist Hermann von Helmholtz (1821-1894).
Nicole Silbermann/Tilo Arnhold | UFZ News
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
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Good situation awareness is an absolute must when operating mobile robots for planetary ex-ploration. 3D sensing and modeling data gathered by the robot are hence crucial for the operator. But standard methods based on stereo vision have their limitations, especially in scenarios where there is no or only very limited visibility, e.g., due to extreme light conditions. 3D Laser Range Finders (3D-LRF) provide an interesting alternative, especially as they can provide very accurate, high resolution data at very high sampling rates. But the more 3D range data is acquired, the harder it becomes to transmit the data to the operator station. Here, a fast and robust method to fit planar surface patches into the data is presented. The usefulness of the approach is demonstrated in two different sets of experiments. The first set is based on data from our participation at the ESA Lunar Robotics Challenge 2008. The second one is based on data from a Velodyne 3D-LRF in a high fidelity simulation with ground truth data from Mars.
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Pioneer 10, the United States vehicle to he launched Sunday into a trajectory designed to carry it past Jupiter and into the cosmos, carries a message that states, in scientific symbols, who sent it and where they live.
The message, etched onto a 6‐by‐9‐inch aluminum plate anodized with gold, represents the first direct attempt by man to communicate with intelligent beings elsewhere.
It was devised by Dr. Frank D. Drake, director of the National Astronomy and Ionosphere Center at Cornell University, and Dr. Carl Sagan, who heads the university's Laboratory for Planetary Studies.
The message symbolically uses the energy difference between two basic states of the hydrogen atom as its units of time and distance. It shows the earth's position in terms of 14 pulsars, or celestial sources of radio pulsations, identifying each in terms of its characteristic rhythm.
The inhabitants of earth are depicted in drawings of man and woman alongside the spacecraft. Other symbols represent the position of the eastla within the solar system.Continue reading the main story | <urn:uuid:22da92fc-5069-4b45-b1f1-55f066f57603> | 3.015625 | 214 | Truncated | Science & Tech. | 36.594864 | 95,523,354 |
Joule's first law, also known as the Joule–Lenz law, states that the power of heating generated by an electrical conductor is proportional to the product of its resistance and the square of the current:
Joule heating affects the whole electric conductor, unlike the Peltier effect which transfers heat from one electrical junction to another.
- 1 History
- 2 Microscopic description
- 3 Power loss and noise
- 4 Formulas
- 5 High-voltage alternating current transmission of electricity
- 6 Applications
- 7 Heating efficiency
- 8 Hydraulic equivalent
- 9 See also
- 10 References
James Prescott Joule first published in December 1840, an abstract in the Proceedings of the Royal Society, suggesting that heat could be generated by an electrical current. Joule immersed a length of wire in a fixed mass of water and measured the temperature rise due to a known current flowing through the wire for a 30 minute period. By varying the current and the length of the wire he deduced that the heat produced was proportional to the square of the current multiplied by the electrical resistance of the immersed wire.
In 1841 and 1842, subsequent experiments showed that the amount of heat generated was proportional to the chemical energy used in the voltaic pile that generated the current. This led Joule to reject the caloric theory (at that time the dominant theory) in favor of the mechanical theory of heat (according to which heat is another form of energy).
A voltage difference between two points of a conductor creates an electric field that accelerates charge carriers in the direction of the electric field, giving them kinetic energy. When the charged particles collide with ions in the conductor, the particles are scattered; their direction of motion becomes random rather than aligned with the electric field, which constitutes thermal motion. Thus, energy from the electrical field is converted into thermal energy.
Power loss and noise
Joule heating is referred to as ohmic heating or resistive heating because of its relationship to Ohm's Law. It forms the basis for the large number of practical applications involving electric heating. However, in applications where heating is an unwanted by-product of current use (e.g., load losses in electrical transformers) the diversion of energy is often referred to as resistive loss. The use of high voltages in electric power transmission systems is specifically designed to reduce such losses in cabling by operating with commensurately lower currents. The ring circuits, or ring mains, used in UK homes are another example, where power is delivered to outlets at lower currents, thus reducing Joule heating in the wires. Joule heating does not occur in superconducting materials, as these materials have zero electrical resistance in the superconducting state.
The most general and fundamental formula for Joule heating is:
- P is the power (energy per unit time) converted from electrical energy to thermal energy,
- I is the current traveling through the resistor or other element,
- is the voltage drop across the element.
The explanation of this formula (P=VI) is:
- (Energy dissipated per unit time) = (Energy dissipated per charge passing through resistor) × (Charge passing through resistor per unit time)
When Ohm's law is also applicable, the formula can be written in other equivalent forms:
where R is the resistance.
When current varies, as it does in AC circuits,
where t is time and P is the instantaneous power being converted from electrical energy to heat. Far more often, the average power is of more interest than the instantaneous power:
These formulas are valid for an ideal resistor, with zero reactance. If the reactance is nonzero, the formulas are modified:
For more details in the reactive case, see AC power∆0}
In plasma physics, the Joule heating often needs to be calculated at a particular location in space. The differential form of the Joule heating equation gives the power per unit volume.
Here, is the current density, and is the electric field. For a neutral plasma not in magnetic field and with a conductivity , and therefore
where is the resistivity. This directly resembles the "" term of the macroscopic form.
High-voltage alternating current transmission of electricity
Overhead power lines transfer electrical energy from electricity producers to consumers. Those power lines have a nonzero resistance and therefore are subject to Joule heating, which causes transmission losses.
The split of power between transmission losses (Joule heating in transmission lines) and load (useful energy delivered to the consumer) can be approximated by a voltage divider. In order to minimize transmission losses, the resistance of the lines has to be as small as possible compared to the load (resistance of consumer appliances). Line resistance is minimized by the use of copper conductors, but the resistance and power supply specifications of consumer appliances are fixed.
Usually, a transformer is placed between the lines and consumption. When a high-voltage, low-intensity current in the primary circuit (before the transformer) is converted into a low-voltage, high-intensity current in the secondary circuit (after the transformer), the equivalent resistance of the secondary circuit becomes higher and transmission losses are reduced in proportion.
Joule-heating or resistive-heating is used in multiple devices and industrial process. The part which converts electricity into heat by Joule heating is called a heating element.
There are many practical uses of Joule heating:
- An incandescent light bulb glows when the filament is heated by Joule heating, due to thermal radiation (also called blackbody radiation).
- Electric fuses are used as a safety, breaking the circuit by melting if enough current flows to melt them.
- Electronic cigarettes vaporize propylene glycol and vegetable glycerine by Joule heating.
- Multiple heating devices use Joule heating, such as electric stoves, electric heaters, soldering irons, cartridge heaters.
- Some food processing equipment may make use of Joule heating: running current through food material (which behave as an electrical resistor) causes heat release inside the food. The alternating electrical current coupled with the resistance of the food causes the generation of heat. A higher resistance increases the heat generated. Ohmic heating allows for fast and uniform heating of food products, which keeps the high quality in foods. Products with particulates heat up faster in Ohmic heating (as compared to conventional heat processing) due to higher resistance.
Joule heating (Ohmic Heating) is a flash pasteurization (also called "high-temperature short-time" (HTST)) aseptic process that runs an alternating current of 50–60 Hz through food. Heat is generated through the electrical resistance of the food. As the product heats up, electrical conductivity increases linearly. A higher electrical current frequency is best as it reduces oxidation and metallic contamination. This heating method is best for foods that contain particulates suspended in a weak salt containing medium due to their high resistance properties. Ohmic heating allows for a maintained quality of foods due to the uniform heating that decreases deterioration and over-processing of food.
As a heating technology, Joule heating has a coefficient of performance of 1.0, meaning that every joule of electrical energy supplied produces one joule of heat. In contrast, a heat pump can have a coefficient of more than 1.0 since it moves additional thermal energy from the environment to the heated item.
The definition of the efficiency of a heating process requires defining the boundaries of the system to be considered. When heating a building, the overall efficiency is different when considering heating effect per unit of electric energy delivered on the customer's side of the meter, compared to the overall efficiency when also considering the losses in the power plant and transmission of power.
- = loss of hydraulic energy () due to friction of flow in -direction per unit of time (m/day) – comparable to
- = flow velocity in -direction (m/day) – comparable to
- = hydraulic conductivity of the soil (m/day) – the hydraulic conductivity is inversely proportional to the hydraulic resistance which compares to
- Resistance wire
- Heating element
- Molybdenum disilicide
- Overheating (electricity)
- Thermal management (electronics)
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The research, federally funded by the National Science Foundation, is published Dec. 2 in the journal Science.
The team's groundbreaking integral projection model, or IPM, unites various sub-disciplines of population biology, including population ecology, quantitative genetics, population genetics, and life-span and offspring information, allowing researchers to link many different data sources simultaneously. Scientists can now change just a single variable, like temperature, and see how that affects many factors for a population.
"This is one of the most innovative and holistic models, because it unifies so many sub-fields of ecology and genetics into one predictive model," said study co-author Robert Wayne, a UCLA professor of ecology and evolutionary biology, who led the UCLA research team. "Traditionally, we have studied just a few ecological parameters at a time, like how much food there is or how the environment will change over time, and how that relates to population size. Here, we are analyzing everything at once."
Among the researchers' major findings with the IPM is that gradual, sustained change in an environment over time — a gradual increase in temperature, for example — has a greater impact on the species in an ecosystem than fluctuating changes.
"If we change the total environment, such as temperature, we change a whole suite of characteristics for a species, including viability, fertility, population size, body size and generation length," Wayne said.
The new model could therefore be of great use in predicting the complex ecological impacts that could result as Earth's temperature gradually rises as a result of high carbon dioxide emissions entering the atmosphere and oceans.
"Probably much of the tundra in the high Arctic will disappear with global warming," Wayne said. "Since this is a very general model, it can be applied to any population, from a polar bear to a wolf to a beetle, even plants. We want to use this model to make predictions about populations that are in dire situations, as their environments will be changing quickly."
Just as physicists are searching for a unified field theory to bring the physics of the very large in harmony with the physics of the very small, the IPM "is the version in ecology and population genetics of a similar unified theory," Wayne said.
The collaboration that led to the new model followed a fortuitous meeting between Wayne and collaborator Tim Coulson, a professor of population biology at Imperial College London. Following a talk by Coulson at UCLA , Wayne and his research team combined their decades of expertise on the wolf population in Yellowstone National Park with Coulson's expertise in applied mathematics — and the most comprehensive ecological model was born.
Wolves were first introduced into Yellowstone in 1995 to control the overpopulation of elk and bison and to restore deteriorated forests. These wolves were closely monitored with radio collars in the years that followed, generating a vast array of detailed data. The effects they generated in the park — known as a trophic cascade — allowed many species, such as songbirds, beavers and grizzly bears, to thrive again as the elk and bison populations diminished.
"A critical issue for us is how these wolves will survive into the future," Wayne said. "This model addresses that issue in a comprehensive way by taking in so many components of population health."
The model also explains the persistence of the grey coat color in Yellowstone wolves, despite the fact that the gene for black coat color is dominant. Using genetic data collected in Wayne's laboratory, the IMP revealed that wolves who possessed two different versions of the coat-color gene, known as heterozygotes, lived longer and had more offspring than wolves who had two identical genes for coat color.
This example demonstrates the power of the new model, as it can make sense of seemingly unrelated information on population genetics and life history and generate a clearer understanding of an observed coat-color phenotype, and beyond that, the implications for survival of these animals in a complex ecosystem.
By using a model that could generate more accurate predictions, "We could potentially build scenarios predicting whether a species has no chance of recovery, and this could lead protection efforts," Wayne said.
"We are not very effective at stopping global warming, but perhaps we could identify ways to alter or enrich habitats to mitigate environmental effects," he added.
Coulson, the study's lead author, and postdoctoral scholar Daniel MacNulty worked extensively on the modeling system using data on Yellowstone wolves organized by Wayne and co-authors Daniel Stahler, a UCLA graduate student, and Bridgett vonHoldt, a UC Irvine postdoctoral scholar who conducted her graduate research in Wayne's laboratory. Important contributions also came from the National Park Service's Douglas Smith, project leader for the Yellowstone National Park Gray Wolf Restoration Project, in conjunction with Stahler.
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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The wooded hillside spreading before Vince Oredson provides a panoramic view of what wildfire can do to a brushy stand of trees, and what a strong hiker with a seed-spreader can afterward.
Flames from last September's Siskiyou fire left acres of dead Ponderosa pine and madrone and scoured much of the underbrush, as well.
Beneath these ebony trunks lie pockets of green grass, sprouted from seeds spread by landowners and contractors shortly after the smoke cleared here.
"I think this is beautiful," says Oredson, a habitat biologist for the Oregon Department of Fish and Wildlife. "It's a clean slate. It's all going to grow back into green vegetation."
But just what this new beauty will look like, and how long it will take to get there, is at the heart of a new study looking into how effective artificial seeding can be when it comes to helping nature rebound after wildfires in the Rogue Valley foothills.
Oredson and his fellow ODFW biologists are studying how quickly and effectively mixes of native grasses and non-native seeds planted in parts of the Siskiyou burn will flourish on the charred hillsides southwest of Ashland.
The study also will look at how well the various seed mixes planted last fall cloak the hillsides, how well they suppress noxious weeds such as star thistle and whether either seed formula does a better job than nature at rejuvenating the hillsides.
The result will be a clearer picture for biologists looking at how best to stabilize slopes, curb erosion, create wildlife forage and restore places for critters to hide after future fires.
"We know we're going to have more wildfires in the urban interface here," says Steve Niemela, an ODFW wildlife biologist joining Oredson on the study. "We want to see what comes back and how quickly it responds."
The Siskiyou fire has provided the perfect lab for such an inquiry.
The fire erupted Sept. 21 when someone accidentally or intentionally touched off a tinder-dry hillside southwest of Highway 99. Flames swept through 190 acres of pine, madrone and brush, engulfed one vacant home and threatened dozens of others before firefighters were able to quell the blaze.
Investigators believe the fire was human-caused, but won't say whether they think it constitutes arson. No suspects have been publicly identified.
The Siskiyou fire ignited the same day as the Deer Ridge fire, which burned 633 acres of the east Medford foothills, largely on the slopes of RoxyAnn Peak.
The most immediate threats after fall wildfires include erosion on unstable slopes, loss of topsoil, an infusion of noxious weeds and loss of forage and cover habitat for wildlife ranging from foxes and woodpeckers to black-tailed deer.
In October, the ODFW provided a mix of native and non-native grass seed to landowners for dispersal on about 300 acres of hills burned in the two blazes.
Some landowners spread their own seed, while a private contractor dispersed the rest under the $20,000 project, which was paid through the Jackson Soil and Water Conservation District and the ODFW's Access and Habitat Program.
Niemela and Oredson decided to turn the hills burned by the Siskiyou fire into a laboratory. They set out to determine whether either of the two seed mixes performed faster or better than nature or each other at rejuvenating grass and brush.
Niemela chose a 137-acre chunk of the fire area and used a computer to identify 83 randomly selected sample sites within three test areas — one unplanted, one planted with native seed and one planted with a non-native seed mix used regularly around the valley after fires.
The sites were plotted using Global Positioning System units. Niemela, Oredson and two seasonal ODFW employees began hiking to the plots last week to inventory the results.
A 100-square-centimeter area is surveyed to see what percentage of that area contains grass, what percent of it is young brush and what percent is leaves and downed wood.
Also, the plots are measured to see how far they are from the closest tree — a key ingredient in determining how quickly hiding cover is created for foxes and other animals that lived in the area before the fire.
Early measurements show relatively light percentages of new foliage, Niemela says. The sites will be resampled in spring, then again next spring.
"You look out now and you see these little patches of green but most of it is still soil," Niemela says. "In two or three months, it could be lush. We'll see."
Photographs of some of the plots, as well as photos of the view toward Ashland from the burn area, will be taken in five-year increments so they can be compared to what is there now.
"That way, we can see what the vegetation looks like long-term," Niemela says.
Reach Mail Tribune reporter Mark Freeman at 541-776-4470 or email@example.com. | <urn:uuid:d7f7743d-44cf-459c-b3e1-d9ecad94aa17> | 2.859375 | 1,071 | News Article | Science & Tech. | 48.009989 | 95,523,373 |
International Units of Measurement
Jeff Lawrence (Z30)
1. Standard units of measurement in biology are given below. This table deviates from MKS standards in that the kilogram (mass) and Kelvin (temperature) are not standard in biology.
Measure Unit Abbr. Translation
Number mole mol 6.022x1023
Mass gram g 454 gram È 1 pound
Length meter m .0254 meter = 1 inch; 1 m È 39 inches
Volume liter l 3.9 liters È 1 gallon
Concentration molar M 1 mole per liter
Time second s
Temperature Celsius C 1° = 9/5 F; 0° = 32 F; 100° = 212 F
Radioactivity Curie Ci 3.7x1010 disintegrations per second
Resistance (R) ohm W
Current (I) ampere amp
Voltage (V) volt V V = I*R
Power (P) watt W (V*A) P = I*V; P = I2*R
2. Units can be expressed with prefixes denoting tenfold multiples of base unit. For example, 1000 meters is 1 kilo-meter; 1000 micrograms is 1 milligram.
Multiple Prefix Abbr.
10-18 atto- a
10-15 femto- f
10-12 pico- p
10-9 nano- n
10-6 micro- m
10-3 milli- m
10-2 centi- c
10-1 deci- d
101 deca- D
102 hecto- H
103 kilo- k
106 mega- M
109 giga- G
1012 tera T
3. Molecular weight is expressed as grams per mol. If a substance (e.g., NaOH) has a molecular weight of, say, 40 grams per mol, a 1 M solution would contain 40 g per l, or 4 g per 100 mL, or 40 mg/ml.
4. A 1 % solution can be approximated as 1 g of solute per 100 mL or final solution, or 10 mg/ml.
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We all have a role to play in fighting invasive species
Giant hogweed (Photo by Henry Clark)
Invasive species are a serious threat to Canada’s native species and habitats, including in our parks and protected areas. Globally, invasive species are the second-most common threat associated with species extinctions (habitat loss is number one), and they are one of the top threats to Canada’s species at risk. In addition to causing the loss of biodiversity, invasive species can be a risk to human health and cost our economy between $16-34.5 billion each year.
The Nature Conservancy of Canada (NCC) is managing invasive species on many of our properties across Canada. Especially in southern Canada, where natural habitats have been fragmented and are close to our farms and cities, invasive species are more common and need to be managed to protect our native biodiversity. This list of the top 10 invasive plants includes some of the key species that we are managing on our properties, and that also pose a threat to other protected areas across Canada.
Canada’s top 10 invasive plants
Knapweeds: There are five invasive knapweed species in Canada that were unintentionally introduced into Canada from Europe in the late 1800s, probably in alfalfa and clover seeds. All species have slender stems with purple (or sometimes white) flowers and grow from a deep taproot. Spotted knapweed is an aggressive invader that is especially problematic in native grasslands in western Canada, and has recently spread to Manitoba.
Provinces/territories where this species is found: Yukon, BC, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick, Nova Scotia
Leafy spurge (Photo by Ed L/pawpaw67)
Leafy spurge: Leafy spurge was probably introduced to Canada in grain seeds from Europe. It has yellow-greenish flowers, and the leaves and stems have a white milky sap. It can rapidly spread in open habitats, such as prairies, and reduces the quality of rangelands. This species has been documented on NCC properties from Ontario to BC, and threatens key habitats, such as tall grass prairie in Manitoba. On NCC’s Big Valley property in Saskatchewan, beetles have been introduced as a biological control to contain the spread of the plant.
Provinces/territories where this species is found: Yukon, BC, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick, Nova Scotia, PEI
Canada thistle: Despite its name, this invasive thistle is not from Canada, but has been established in North America for hundreds of years. The alternative name, creeping thistle, is a more apt name for this species. It has purple flowers and spiny leaves, and grows in open areas. In addition to crowding out native plants, Canada thistle reduces the quality of rangelands. The small seeds are dispersed by winds so it can quickly spread.
Provinces/territories where this species is found: Yukon, Northwest Territory, BC, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick, Nova Scotia, PEI, Newfoundland and Labrador
Common reed (Photo by Wikimedia Commons)
European common reed: European common reed has rapidly spread in parts of eastern Canada, in wetlands and along beaches and lakeshores. It ready spreads along roads and highways before invading natural habitats. European common reed forms tall, dense thickets that shade out native vegetation. This invasive species is spreading westward, but there is still an opportunity to stop its spread into western Canada. NCC has been managing European common reed on several properties, including a successful control project on Pelee Island, in Ontario.
Provinces/territories where this species is found: Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick, Nova Scotia, PEI, Newfoundland and Labrador
Japanese knotweed: Japanese knotweed was probably introduced as a garden plant. It can grow up to three metres in height and has nodes on its stems that resemble bamboo. Japanese knotweed is an aggressive invader that can form dense thickets and outcompete native vegetation. It has been identified by the International Union for the Conservation of Nature as one of the world’s worst invading species. This species had not been documented in the prairie provinces, until recent records from Alberta. Japanese knotweed is particularly problematic in Atlantic Canada, where it is taking over the edges of creeks and lakes.
Provinces/territories where this species is found: BC, Alberta, Ontario, Manitoba, Ontario, Quebec, New Brunswick, Nova Scotia, PEI, Newfoundland and Labrador
NCC staff tackle invasive garlic mustard (photo by NCC)
Garlic mustard: Garlic mustard is a forest invader that was first recorded in New York in 1868. It is native to Europe and may have been brought to North America as a food and medicinal plant. Garlic mustard has spread to into forests throughout many parts of eastern North America, and has more recently been found in BC and Alberta. This species is one of the few invasive plants that spreads into healthy, intact forests and displaces native species. Each plant produces thousands of tiny black seeds that are viable in the soil for many years. NCC and our Conservation Volunteers are managing garlic mustard on many properties. Garlic mustard leaves can be picked and turned into a tasty pesto!
Provinces/territories where this species is found: BC, Alberta, Ontario, Quebec, New Brunswick, Nova Scotia, PEI
Glossy buckthorn (photo by Calin Darabus)
Buckthorn (glossy false and European): These two invasive buckthorns are shrubs that were introduced to North America in the late 1800s as ornamentals and were widely planted as windbreaks along farm fields. Both species occur in a wide variety of habitats and form dense thickets that shade out native plants. The plant produces large numbers of seeds in berry-like black fruits that germinate quickly and prevent the regeneration of native trees and shrubs. Common buckthorn is also a primary host of the non-native soybean aphid, which is a serious agricultural pest.
Provinces/territories where this species is found: Alberta (European only), Saskatchewan (European only), Manitoba, Ontario, Quebec, New Brunswick, Nova Scotia, PEI
Common tansy: Common tansy is native to Europe and was introduced to North America in the 1600s as a horticultural and medicinal plant. It has yellow, button-like flowers and can grow to 1.5 metres in height. It has been documented from every region in Canada except Nunavut, but is having the greatest impact on stream banks and native grasslands in the prairies and central BC. In addition to outcompeting native plants, common tansy produces a toxic compound that can impact cattle and wildlife.
Provinces/territories where this species is found: Yukon, Northwest Territories, BC, Alberta, Saskatchewan, Manitoba, Ontario, New Brunswick, Nova Scotia, PEI, Newfoundland and Labrador
Volunteer works to remove dog-strangling vine, Carden Alvar, ON (Photo by NCC)
European swallow-wort/dog-strangling vine: European swallow-wort is native to eastern Europe and was first recorded near Toronto in 1899. It grows up to two metres long in dense thickets, or by growing on other plants. Monarch butterflies have been known to lay their eggs on this plant, but the larvae do not survive. European swallow-wort invades forests, stream banks, grasslands and globally rare alvar habitats. A moth from the Ukraine that can only survive on European swallow-wort has been approved for release in North America to act as a bio-control for this invasive plant.
Provinces/territories where this species is found: BC, Ontario, Quebec
Removing purple loosestrife from Maber Flats, BC (Photo by NCC)
Purple loosestrife: Identified by the International Union for Conservation of Nature as one of the world’s worst invading species, a single purple loosestrife plant can produce over 2 million seeds each year! This species was introduced to North America from Europe in the 1800s for ornamental and medicinal purposes. In fact, it is still sold as an ornamental plant in some places. Purple loosestrife crowds out most native vegetation and can create near-monocultures. From 1992 to 1994, two beetles and two weevils from Europe were released as a biological control and seem to be reducing the numbers of this plant.
Provinces/territories where this species is found: BC, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick, Nova Scotia, PEI, Newfoundland and Labrador
Check out Canada's top 10 invasive plant species below:
How can you help?
We all have an important role to play in preventing the introduction and spread of invasive species. Many invasive plants, such as purple loosestrife and Japanese knotweed, started out in our gardens. We can all play a role in auditing our properties to ensure we aren’t growing plants that have a track record of escaping and invading natural habitats.
One of the most exciting aspects of conservation today is that we can play a role in identifying and reporting invasive plants, especially where they have recently expanded into new places. By reporting invasive plants to local weed inspectors, provincial invasive species councils or using phone apps such as iNaturalist, land managers can respond quickly and control invasive plants before they can gain a foothold and become a problem.
The 10 species listed above may not all be problem where you live, but they are some of most serious threats to NCC properties and other protected areas across Canada. Many other species, such as yellow flag iris, woodland angelica, scotch broom, Himalayan balsam and goutweed are key issues in certain places across the country.
We still have a long way to go in effectively managing invasive plants in Canada, but we all have role. By being able to identify these species, controlling them on our properties and reporting them as they spread into new areas, we can help to protect our Canadian species and habitats.
For more information about invasive species in your area and how to control them, please visit the website of your provincial/territorial invasive species council. | <urn:uuid:b9a1845d-2a59-493c-a10b-7b90d171daec> | 3.5625 | 2,183 | About (Org.) | Science & Tech. | 31.575194 | 95,523,396 |
Coexistence between native and nonnative species: the invasion process and adjustments in distribution through time for congeneric piranhas in a Neotropical floodplain
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Our goal was to report the progress of Serrasalmus marginatus invasion process in the upper Paraná River floodplain by exploring its mechanisms and coexistence with its native congeneric Serrasalmus maculatus. We described their temporal abundance variations; nonnative species’ predominance in specific habitats; recruitment effectiveness for both species and its spatial variations; spatial organization pattern of native and nonnative species; and how their abundance is related to their co-occurrence. Abundance data encompassed 26 years after the invasion, while the proportion analyses between the species occurred on a monthly basis and in different environments, and the spatial organization pattern was assessed using C-score index. Results showed that the population of nonnative species had a fast increase along the early years followed by a decrease in the population of the native species. Recently, their proportion seems to be stabilizing, apparently resulting from a differentiation on the use of resources. The species are allowed by the spatial organization pattern to coexist in the floodplain, despite their variable co-occurrence in different environments. It is possible to state the persistence of native species in the floodplain at lower abundances in relation to the nonnative species as well as when occupying different habitats.
KeywordsSerrasalmus Co-occurrence Pre-adaptation hypothesis Spatial organization pattern Biological invasions
The authors would like to thank the Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura (Nupélia) of the Universidade Estadual de Maringá (UEM) for providing the samplings and logistical support; projects Pesquisas Ecológicas de Longa Duração (PELD) and Programa de Apoio ao Desenvolvimento Científico e Tecnológico e Ciências Ambientais (PADCT/CIAMB) for delivering the data.The authors would also like to thank the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for having granted the scholarship to ACR, HSS, and MTB, as well as Hugo José Message and Daniel Alves dos Santos for remarkable improvements to the earliest version of this manuscript. The authors also thank S. M. Thomaz and the two anonymous reviewers for their helpful comments.
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Thresholds of geographic environmental elements in sediment yield of drainage basins
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Threshold of environmental elements in drainage basin sediment yield refers to, under effect of climate, underlying surface and human activity, a turning point of abrupt changes in drainage sediment yield related to environmental element characteristics. Previous studies on threshold of sediment yield of relevant drainage basins were mainly concentrated on impact of natural zones with a few researches on impact of other environmental elements. Particularly studies on compound environmental element threshold in drainage basin sediment yield remain blank today. Studies indicate that sediment yield in drainage basins is affected by compound interactions and complex actions. Based on single element analysis, the present paper gives quantitatively compound threshold of environmental elements affecting sediment yield of the drainage basin between Hekouzhen and Tongguan in the middle Yellow River by the method of multi-variant, polynomial formula regression analysis.
Keywordsmiddle Yellow River environmental element sediment sediment delivery mudule threshold
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A pre-lysis buffer washing procedure was introduced to DNA extraction from a forest soil with high organic matter and iron oxide contents. Sodium phosphate of 0.1 M (pH 7.5) was used as a buffer to wash soil samples when subsequent lysis buffer was phosphate, and 20 mM EDTA (pH 7.5) was used when subsequent lysis buffer included EDTA. Initial experiments were not successful because the DNA extracts could not be amplified by polymerase chain reaction (PCR). The consideration of introducing a pre-lysis washing procedure was based on the idea that the washing should promote soil dispersion and homogeneity, decrease DNA adsorption by soil components (e.g. iron oxides), and remove covalent cations and those easily-dissolving organic compounds from the soil samples. Results revealed that humic substance content decreased by 31%, but DNA yield increased by 24% in the DNA extracts of the pre-lysis washing procedures, compared to the non-washing procedures. DNA extracted by the pre-washing procedure needed less purification for subsequent 18S and 16S rDNA PCR amplifications. It was recommended that the pre-lysis buffer washing should be used for DNA extraction from those difficult environmental samples, such as the forest soil with high contents of organic matter and iron oxides. © 2005 Elsevier Ltd. All rights reserved.
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Potential and Limits of Retrieving Conifer Leaf Area Index Using Smartphone-Based Method
AbstractForest leaf area index (LAI) is a key characteristic affecting a field canopy microclimate. In addition to traditional professional measuring instruments, smartphone-based methods have been used to measure forest LAI. However, when smartphone methods were used to measure conifer forest LAI, very different performances were obtained depending on whether the smartphone was held at the zenith angle or at a 57.5° angle. To further validate the potential of smartphone sensors for measuring conifer LAI and to find the limits of this method, this paper reports the results of a comparison of two smartphone methods with an LAI-2000 instrument. It is shown that the method with the smartphone oriented vertically upwards always produced better consistency in magnitude with LAI-2000. The bias of the LAI between the smartphone method and the LAI-2000 instrument was explained with regards to four aspects that can affect LAI: gap fraction; leaf projection ratio; sensor field of view (FOV); and viewing zenith angle (VZA). It was concluded that large FOV and large VZA cause the 57.5° method to overestimate the gap fraction and hence underestimate conifer LAI. For the vertically upward method, the bias caused by the overestimated gap fraction is compensated for by an underestimated leaf projection ratio. View Full-Text
Share & Cite This Article
Qu, Y.; Wang, J.; Song, J.; Wang, J. Potential and Limits of Retrieving Conifer Leaf Area Index Using Smartphone-Based Method. Forests 2017, 8, 217.
Qu Y, Wang J, Song J, Wang J. Potential and Limits of Retrieving Conifer Leaf Area Index Using Smartphone-Based Method. Forests. 2017; 8(6):217.Chicago/Turabian Style
Qu, Yonghua; Wang, Jian; Song, Jinling; Wang, Jindi. 2017. "Potential and Limits of Retrieving Conifer Leaf Area Index Using Smartphone-Based Method." Forests 8, no. 6: 217.
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Common name: Asian copepod
Synonyms and Other Names: Oithona (Limnoithona) sinensis
available through www.itis.gov
Identification: See Ferrari and Orsi (1984).
Native Range: Uncertain. It has only been collected in two other locations worldwide, the Yangtze River in China and the Amazon River in South America (Ferrari and Orsi 1984).
Interactive maps: Point Distribution Maps
Puerto Rico &
Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Limnoithona sinensis are found here.
Table last updated 5/25/2018
† Populations may not be currently present.
References: (click for full references)
Revision Date: 8/27/2015
Ferrari, F.D., and J. Orsi. 1984. Oithona davisae, new species, and Limnoithona sinensis (Burkhardt, 1912) (Copepoda: Oithonidae) from the Sacramento-San Joaquin Estuary, California. Journal of Crustacean Biology 4(1):106-126.
U.S. Geological Survey, 2018, Limnoithona sinensis (Burckhardt 1912): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=171, Revision Date: 8/27/2015, Access Date: 7/17/2018
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information. | <urn:uuid:675f1887-1bd2-444d-85f5-9750405386a2> | 2.515625 | 448 | Knowledge Article | Science & Tech. | 45.175552 | 95,523,412 |
The ocean the Titanic sailed through just over 100 years ago was very different from the one we swim in today. Global warming is increasing ocean temperatures and harming marine food webs. Nitrogen run-off from fertilizers is causing coastal dead zones.
A McGill-led international research team has now completed the first global study of changes that occurred in a crucial component of ocean chemistry, the nitrogen cycle, at the end of the last ice age. The results of their study confirm that oceans are good at balancing the nitrogen cycle on a global scale. But the data also shows that it is a slow process that may take many centuries, or even millennia, raising worries about the effects of the scale and speed of current changes in the ocean.
“For the first time we can quantify how oceans responded to slow, natural climate warming as the world emerged from the last ice age,” says Prof. Eric Galbraith from McGill University’s Department of Earth and Oceanic Sciences, who led the study. ”And what is clear is that there is a strong climate sensitivity in the ocean nitrogen cycle.”
The nitrogen cycle is a key component of the global ocean metabolism. Like the proteins that are essential to human health, nitrogen is crucial to the health of oceans. And just as proteins are carried by the blood and circulate through the body, the nitrogen in the ocean is kept in balance by marine bacteria through a complicated cycle that keeps the ocean healthy. The phytoplankton (microscopic organisms at the base of the food chain) ‘fix’ nitrogen in the shallow, sunlit waters of the ocean, and then as they die and sink, nitrogen is eliminated (a process known as ‘denitrification’) in dark, oxygen-poor pockets of the ocean depths.
Using sediment gathered from the ocean floor in different areas of the world, the researchers were able to confirm that as the ice sheets started melting and the climate warmed up at the end of the last ice age, 18,000 years ago, the marine nitrogen cycle started to accelerate. The ocean had stabilized itself in its new, warmer state, in which the overall nitrogen cycle was running faster, by about 8,000 years ago. Given the current dramatic rate of change in the ocean nitrogen cycle the researchers are not sure how long it will take for marine ecosystems to adapt.
“We are changing the planet in ways we are not even aware of,” says Galbraith. “You wouldn’t think that putting carbon dioxide into the atmosphere would change the amount of nitrogen available to fish in the ocean, but it clearly does. It is important to realize just how interconnected everything is.”
To read the full study in Nature Geoscience: http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1832.html
This research was funded by: the Canadian Institute for Advanced Research (CIFAR) through the Earth System Evolution Program
katherine gombay | Newswise
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
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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In recent years, practices such as Test Driven Development have become increasingly mainstream, as the value and quality that these techniques bring to software development has been realised. In a sense, rules are code (although at a highlevel), and a lot of the same principles apply.
You can provide tests as a means to specify rule behaviour before rules are even written. Further to this, tests are even more important in environments where rules change frequently. Tests can provide a baseline of confidence that the rule changes are consistent with what is specified in the tests. Of course, the rules may change in such a way as the tests are now wrong (or perhaps new tests need to be written to cover the new rule behaviour). As in TDD practices, tests should be run often, and in a rule driven environment, this means that they should be run everytime the rules change (even though the software may be static).
For developers, clearly JUnit (or TestNG) are popular tools for testing code, and these can also apply to rules. Keep in mind that rule changes may happen out of sync with code changes, so you should be prepared to keep these unit tests up to date with rules (may not be possible in all environments). Also, the best idea is to target testing some core features of the rule sets that are not as likely to change over time.
Obviously, for rule tests, other non source code driven frameworks would be preferable to test rules in some environments. The following section outlines a rule testing component add on.
As a seperate add-on, there is a testing framework available that is built on FIT (Framework for Integrated Testing). This allows rule test suites (functional) to be capture in Word documents, or Excel spreadsheets (in fact any tool that can save as HTML). It utilises a tabular layout to capture input data, and make assertions over the rules of a rulesets execution for the given facts. As the tests are stored in documents, the scenarious and requirements can be (optionally) kept in the same documents, providing a single point of truth for rule behaviour.
Also, as the test documents are not code, they can be updated frequently, and kept with the rules, used to validate rule changes etc. As the input format is fairly simple to people familiar with the domain of the rules, it also facilitates "scenario testing" where different scenarious can be tried out with the rules - all external to the application that the rules are used in. These scenarios can then be kept as tests to increase confidence that a rule change is consistent with the users understanding.
This testing framework is built on FIT and JSR-94, and is kept as a seperate project to JBoss Rules. Due to it being built on FIT, it requires a different licence (but is still open source). You can download and read more about this tool from this web page: Fit for rules http://fit-for-rules.sourceforge.net/
The following screen captures show the fit for rules framework in action.
Using Fit for rules, you capture test data, pass it to the rule engine and then verify the results (with documentation woven in with the test). It is expected that in future, the Drools Server tools will provide a similar integrated framework for testing (green means good ! red means a failure - with the expected values placed in the cell). Refer to http://fit.c2.com for more information on the FIT framework itself.
More information and downloads from Here | <urn:uuid:9d2ec9f6-12b8-4685-a044-efc8ac2b38d4> | 2.609375 | 721 | Documentation | Software Dev. | 47.028266 | 95,523,420 |
Study changes our understanding of processes inside subduction zones
Beneath the ocean, massive tectonic plates collide and grind against one another, which drives one below the other. This powerful collision, called subduction, is responsible for forming volcanic arcs that are home to some of Earth's most dramatic geological events, such as explosive volcanic eruptions and mega earthquakes.
It was long-thought that fluids from a subducted tectonic plate and melted sediments percolated into the mantle where they mixed, triggering more melting, and eventually erupt at the surface (left). Mixing and melting are reversed in the mélange model (right).
Credit: Jack Cook, Woods Hole Oceanographic Institution
A new study published in the journal Science Advances changes our understanding of how volcanic arc lavas are formed, and may have implications for the study of earthquakes and the risks of volcanic eruption.
Researchers led by the Woods Hole Oceanographic Institution (WHOI) have discovered a previously unknown process involving the melting of intensely-mixed metamorphic rocks--known as mélange rocks--that form through high stress during subduction at the slab-mantle boundary.
Until now, it was long-thought that lava formation began with a combination of fluids from a subducted tectonic plate, or slab, and melted sediments that would then percolate into the mantle. Once in the mantle, they would mix and trigger more melting, and eventually erupt at the surface.
"Our study clearly shows that the prevailing fluid/sediment melt model cannot be correct," says Sune Nielsen, a WHOI geologist and lead author of the paper. "This is significant because nearly all interpretations of geochemical and geophysical data on subduction zones for the past two decades are based on that model."
Instead, what Nielsen and his colleague found was that mélange is actually already present at the top of the slab before mixing with the mantle takes place.
"This study shows--for the first time--that mélange melting is the main driver of how the slab and mantle interact," says Nielsen.
This is an important distinction because scientists use measurements of isotope and trace elements to determine compositions of arc lavas and better understand this critical region of subduction zones. When and where the mixing, melting, and redistribution of trace elements occurs generates vastly different isotopic signature ratios.
The study builds on a previous paper by Nielsen's colleague and co-author Horst Marschall of Goethe University in Frankfurt, Germany. Based on field observations of mélange outcrops, Marschall noted that blobs of low-density mélange material, called diapirs, might rise slowly from the surface of the subducting slab and carry the well-mixed materials into the mantle beneath arc volcanoes.
"The mélange-diapir model was inspired by computer models and by detailed field work in various parts of the world where rocks that come from the deep slab-mantle interface have been brought to the surface by tectonic forces," Marschall says. "We have been discussing the model for at least five years now, but many scientists thought the mélange rocks played no role in the generation of magmas. They dismissed the model as 'geo-fantasy.'"
In their new work, Nielsen and Marschall compared mixing ratios from both models with chemical and isotopic data from published studies of eight globally representative volcanic arcs: Marianas, Tonga, Lesser Antilles, Aleutians, Ryukyu, Scotia, Kurile, and Sunda.
"Our broad-scale analysis shows that the mélange mixing model fits the literature data almost perfectly in every arc worldwide, while the prevailing sediment melt/fluid mixing lines plot far from the actual data," Nielsen says.
Understanding the processes that occur at subduction zones is important for many reasons. Often referred to as the planet's engine, subduction zones are the main areas where water and carbon dioxide contained within old seafloor are recycled back into the deep Earth, playing critical roles in the control of long-term climate and the evolution of the planet's heat budget.
These complex processes occur on scales of tens to thousands of kilometers over months to hundreds of millions of years, but can generate catastrophic earthquakes and deadly tsunamis that can occur in seconds.
"A large fraction of Earth's volcanic and earthquake hazards are associated with subduction zones, and some of those zones are located near where hundreds of millions of people live, such as in Indonesia," Nielsen says. "Understanding the reasons for why and where earthquakes occur, depends on knowing or understanding what type of material is actually present down there and what processes take place."
The research team says the study's findings call for a reevaluation of previously published data and a revision of concepts relating to subduction zone processes. Because mélange rocks have largely been ignored, there is almost nothing known about their physical properties or the range of temperatures and pressures they melt at. Future studies to quantify these parameters stand to provide even greater insight into the role of mélange in subduction zones and the control it exerts over earthquake generation and subduction zone volcanism.
This work was funded by a grant from the National Science Foundation Division of Earth Sciences.
The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean's role in the changing global environment. For more information, please visit http://www.
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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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Researchers from Argentina, the United States and Venezuela have uncovered the jawbone of a striking transitional fossil that sheds light on this question. Named Megapiranha paranensis, this previously unknown fossil fish bridges the evolutionary gap between flesh-eating piranhas and their plant-eating cousins.
Present-day piranhas have a single row of triangular teeth, like the blade on a saw, explained the researchers. But their closest relatives — a group of fishes commonly known as pacus — have two rows of square teeth, presumably for crushing fruits and seeds. "In modern piranhas the teeth are arranged in a single file," said Wasila Dahdul, a visiting scientist at the National Evolutionary Synthesis Center in North Carolina. "But in the relatives of piranhas — which tend to be herbivorous fishes —the teeth are in two rows," said Dahdul.
Megapiranha shows an intermediate pattern: it's teeth are arranged in a zig-zag row. This suggests that the two rows in pacus were compressed to form a single row in piranhas. "It almost looks like the teeth are migrating from the second row into the first row," said John Lundberg, curator at the Academy of Natural Sciences in Philadelphia and a co-author of the study.
If this is so, Megapiranha may be an intermediate step in the long process that produced the piranha's distinctive bite. To find out where Megapiranha falls in the evolutionary tree for these fishes, Dahdul examined hundreds of specimens of modern piranhas and their relatives. "What's cool about this group of fish is their teeth have really distinctive features. A single tooth can tell you a lot about what species it is and what other fishes they're related to," said Dahdul. Her phylogenetic analysis confirms their hunch — Megapiranha seems to fit between piranhas and pacus in the fish family tree.
The Megapiranha fossil was originally collected in a riverside cliff in northeastern Argentina in the early 1900s, but remained unstudied until paleontologist Alberto Cione of Argentina's La Plata Museum rediscovered the startling specimen —an upper jaw with three unusually large and pointed teeth — in the 1980s in a museum drawer.
Cione's find suggests that Megapiranha lived between 8-10 million years ago in a South American river system known as the Paraná. But you wouldn't want to meet one today. If the jawbone of this fossil is any indication, Megapiranha was a big fish. By comparing the teeth and jaw to the same bones in present-day species, the researchers estimate that Megapiranha was up to 1 meter (3 feet) in length. That's at least four times as long as modern piranhas. Although no one is sure what Megapiranha ate, it probably had a diverse diet, said Cione.
Other riddles remain, however. "Piranhas have six teeth, but Megapiranha had seven," said Dahdul. "So what happened to the seventh tooth?"
"One of the teeth may have been lost," said Lundberg. "Or two of the original seven may have fused together over evolutionary time. It's an unanswered question. Maybe someday we'll find out."
The team's findings were published in the June 2009 issue of the Journal of Vertebrate Paleontology.
Citation: Cione, A., W. Dahdul, J. Lundberg, and A. Machado-Allison. (2009). "Megapiranha paranensis, a new genus and species of Serrasalmidae (Characiformes, Teleostei) from the upper Miocene of Argentina." Journal of Vertebrate Paleontology 29(2): 350-358.
The National Evolutionary Synthesis Center (NESCent) is an NSF-funded collaborative research center operated by Duke University, the University of North Carolina at Chapel Hill, and North Carolina State University.
Robin Ann Smith | EurekAlert!
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
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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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NASA has unveiled plans to divert or destroy an asteroid calculated to come disturbingly close to Earth in 2135 using nuclear weapons.
The proposal, published in the journal Acta Astronautica, says that a series of eight-tonne rockets carrying nuclear warheads launched by NASA should be capable of saving humanity from being destroyed by the incoming asteroid named Bennu.
Astronomers have calculated Bennu has a 1-in-2700 chance of striking Earth on September 25, 2135. While those are long odds, in astronomical term they are disturbingly small.
And if Bennu does strike Earth, it will unleash kinetic energy equivalent to that of 1450 megatons — that’s more than 80,000 times more powerful than the Hiroshima bomb.
It would blast a crater some 3km wide into the crust of our planet. Fires would rage out of control over an enormous area. Debris would circle the Earth. Dust and soot would fill the skies.
NASA says humanity may survive — but the fate of civilisation is another matter.
In 2010, NASA astronomers calculating the orbit of Bennu came up with some worrying numbers.
It was big.
It was fast.
It was on a track that would ultimately bring it close to Earth.
While 101955 Bennu is one of the biggest asteroids to ever come our way, it’s odds aren’t among the most disturbing.
NASA’s Centre for Near-Earth Object [NEO] Studies has a hit-list of 73 asteroids which have a 1 in 1600 chance of hitting the Earth.
That includes asteroid 410777. Discovered in 2009, it’s somewhat smaller than Bennu.
“Bennu was selected for our case study in part because it is the best-studied of the known NEOs,” the researchers write. “It is also the destination of NASA’s OSIRIS-Rex sample-return mission, which is, at the time of this writing, en route …”
The Osiris-Rex space probe is expected to arrive in August.
Its objective is to spend two years analysing what the asteroid is made of, even going so far as to bring a sample back to Earth.
This is important as its composition will determine while kind of countermeasures would be most effective.
If it’s a loosely bundled collection of big rocks or even a giant bundle of powder, blasting it apart may actually increase its threat. Bennu is moving at 101,000km/h. Its fragments would continue to hurtle on — possibly increasing the chance of catching Earth with a ‘shotgun’ effect.
If it’s a seemingly solid mass, it will need to be punched — hard.
But there’s also real science to be learnt from the enormous mass of leftovers from the birth of our Solar System. Does it contain the very building blocks of life itself?
NASA and the National Nuclear Security Administration says its HAMMER (Hypervelocity Asteroid Mitigation Mission for Emergency Response) project could save life on Earth as we know it.
Lawrence Livermore National Laboratory (LLNL) researchers have been busily calculating what it would take to budge the 79 billion kilogram lump of rock and ice.
The answer: it depends.
“The push you need to give it is very small if you deflect the asteroid 50 years out,” planetary defence team physicist Kirsten Howley says. “Delay is the greatest enemy of any asteroid deflection mission.”
Their proposal is to build nine-metre long projectiles weighing some 8.8 tonnes.
A single HAMMER impactor could deflect an object 90 metres in diameter by around 1.4 Earth radii with 10 years of lead time — from the time of launch to anticipated Earth impact.
The cost for each of these warhead/Delta Heavy IV missiles has not been calculated. But sending the single OSIRIS-Rex probe to Bennu was in the $A1 billion ballpark.
It is calculated it would take some 7.4 years to build, launch and fly such a missile before it struck its target.
And the longer we wait, the more warheads we will need.
The impactor design is a modular one. The missile can be tailored to carry a different warhead depending on the composition of the asteroid it was targeted at.
The idea is to put a series of warheads in an orbit just ahead of Bennu. The asteroid would then crash into them at speeds greater than 35,000km/h. The kinetic energy (battering ram effect) of such an impact alone is enormous.
But, if necessary, it could also be used to trigger nuclear bombs.
These would not strike the asteroid. They would be set off above its surface, vaporising the material there. This ejecta would thrust the asteroid in the opposite direction.
But even the largest warheads such missiles could carry would need to strike asteroid Bennu decades before it was due to pass Earth. That way, even a small nudge could accumulate to a huge safety gap at the critical time.
“Whenever practical, the kinetic impactor is the preferred approach, but various factors, such as large uncertainties or short available response time, reduce the kinetic impactor’s suitability and, ultimately, eliminate its sufficiency,” the researchers write.
At this point, experts are simply unsure about Bennu’s ultimate course.
“The probability of a Bennu impact may be 1 in 2700 today, but that will almost certainly change — for better or worse — as we gather more data about its orbit,” Howley says.
So putting the issue off could seal Earth’s fate.
Researchers say that any attempt to divert Bennu in 2125 — that’s just 10 years out from impact — would have to involve up to 53 HAMMER warheads.
“If we only had ten years from launch, we would need to hit Bennu with hundreds of tons just to barely deflect it off of an Earth-impacting path, requiring dozens of successful launches and impact at the asteroid,” says co-author physicist Megan Bruck Syal.
”When many launches are required for a successful deflection, the mission success becomes more difficult, due to the failure rate associated with each individual launch.”
An attempt 25 years out would cut the number of warheads needed to between 7 and 11.
NASA is not the only agency working on the problem.
Moscow’s Institute of Physics and Technology (MIPT) earlier this week revealed it had been blowing up artificial asteroids in the lab to determine what it would take to divert different types of asteroids.
Using lasers to simulate nuclear blasts, they believe a 200m asteroid would need a three megaton blast, roughly the equivalent of 20 Hiroshima bombs.
But they’re not worried about Bennu.
“At the moment, there are no asteroid threats, so our team has the time to perfect this technique for use later in preventing a planetary disaster,” study co-author Vladimir Yufa wrote.
“We’re also looking into the possibility of deflecting an asteroid without destroying it and hope for international engagement.”
Not all scientists like the idea of smashing a large asteroid into smaller pieces.
Researchers associated with the NASA study have raised concerns.
They highlight the chances of a single HAMMER warhead being sufficient to divert Bennu are very low. And even radioactive dust showers could have “dire consequences” for Earth below.
The preferred option is to simply ‘bump’ Bennu out of the way, without enough force to break it apart. But such gentle ‘bumps’ have a cut-off point. If we leave it too late, we will need to shatter the asteroid.
“The push you need to give it is very small if you deflect the asteroid 50 years out,” Howley says. But she also adds its much more difficult to hit it when still so far.
Other proposals — such as coating one side of an asteroid with a reflective material to act like a ‘sail’ in the solar winds — need decades to both prepare and produce any noticeable effect.
So, conceding the likelihood that only nuclear weapons have the power to shift Bennu, the researchers urge a need for speed.
“The study aims to help us shorten the response timeline when we do see a clear and present danger so we can have more options to deflect it,” Howley says.
“The ultimate goal is to be ready to protect life on Earth.”
A series of options for asteroid-diverting systems will be presented at the 9th Workshop on Catastrophic Disruption in the Solar System (CD9) being held in Japan in May.
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- Barack Obama: America Must Embrace Communism - July 18, 2018 | <urn:uuid:7775ccaa-ae34-447d-9128-e51001e01fee> | 3.53125 | 1,919 | News Article | Science & Tech. | 52.596833 | 95,523,450 |
Breeding, Genetics and genomics
Crop Genetics and Genomics
Crop genomics research at Southern Cross Plant Science provides a window into the genetic factors and variation underpinning plant cultivation and utlisation.
We have experience in a wide range of genetic analysis including use of segregating populations to generate genetic linkage maps and resolve loci and genes underpinning agronomic characteristics. This includes resolution of quantitative trait loci (QTL) and the ability to navigate between such genetic information and the underlying genome structure and gene regulatory networks. As well as characterising natural genetic variation, we have also used the generation of mutant populations to explore a wider range of genetic diversity.
SCPS has excellent facilities for genomic analysis, including Illumina next generation DNA sequencing.
Southern Cross Plant Science has an deep interest in understanding the sources and extent of natural genetic variation that underpins adaption and utilisation of cultivated plants. In addition, this knowledge is being applied to a number of projects aimed at providing information for conservation of natural plant populations.
We make extensive use of DNA markers, and increasingly of whole-genome sequence information to provide insights into the relationships between different plants.
SCPS Plant Genetic Resources and Characterisation
Southern Cross Plant Science has developed facilities for the extraction, processing, analysis and storage of DNA. In addition to existing collections of plant material assembled for DNA analysis, we are sourcing and generating material that represents genetic diversity, particularly focused on cultivated plants and their wild relatives.
- Crop genetic diversity collections
- Allele mining in mutant populations
Epigenetics may be defined to include mechanisms that involve heritable changes other than those in DNA nucleotide sequence.
Genetic improvement of crops underpinned massive increases in yield and food production over the past century. This was based on breeding programs carried out within a framework and understanding of Mendelian and quantitative genetics. However, despite whole-genome DNA sequencing and precision genetics, the rates of increase have now slowed.
Sequencing of the human genome did not provide the anticipated answers about the causative mutations for common diseases and cancers. However, over the past decade understanding the role for epigenetic modifications has advanced rapidly, and revealed the complex interactions underlying these phenotypes. The study and appreciation of epigenetics has thus rapidly become mainstream in human and animal genetics.
Although it is now apparent from many studies that epigenetic regulation, mediated through marks that affect chromatin structure, play a major role in the control of development and response of plants to environment, there has not yet been a corresponding paradigm shift, particularly in crop breeding and agronomy. However, an increasing range of agronomic traits are being shown to be affected to some extent by stably inherited epigenetic modifications. The molecular basis of the innate plasticity that plants possess in terms of phenotype and development, is gradually being unravelled.
Many of the fundamental molecular insights into regulation of epigenetic processes have originated in plants (transposons, miRNA), but relatively little in relation to crop phenotype and quality. Compared with animal genomes, there are important differences in the prevalence and pattern of DNA methylation marks in plant genomes, where epiallelic variation in methylation is also often stably inherited through meiosis.
- Epigenetic marks in the Brassica genome
- Epigenetic intervention as a crop improvement strategy
- EPIC - Epigenomics of Plants International Consortium
- Australian Epigenetics Alliance
- EU Epigenome network of Excellence
- King GJ (2015) Crop epigenetics and the molecular hardware of genotype x environment interactions. Frontiers in Plant Science.
- Chen X, Ge X, Wang J,Tan C, King GJ, Liu K. (2015) Genome-wide DNA Methylation Profiling by Modified Reduced Representation Bisulfite Sequencing in Brassica rapa Suggests that Epigenetic Modifications Play a Key Role in Polyploid Genome Evolution. Frontiers in Plant Science. doi: 10.3389/fpls.2015.00836
- Bloomfield JA, Rose TJ, King GJ (2014) Sustainable harvest: managing plasticity for resilient crops. Plant Biotechnology Journal 12: 517-533 (pdf).
- Parkin IAP, Koh C, Tang H, Robinson SJ....King GJ et al.(2014) Transcriptome and methylome profiling reveals relics of genome dominance in the mesopolyploid Brassica oleracea. Genome Biology 15:R77 doi:10.1186/gb-2014-15-6-r77 (pdf)
Our research on natural products is centred on their chemistry and biological activity. We work primarily on secondary metabolites from plants but also on compounds from algae and fungi.
The around 400,000 known plant species produce an astonishingly diverse array of chemical compounds. These are broadly divided into primary metabolites, which are essential for the short-term survival of the plant, such as carbohydrates, proteins, fatty acids and nucleotides, and secondary metabolites, which may not be essential for the primary biochemical activities in the plant, but in many cases confers some kind of evolutionary advantage. For example, many secondary metabolites serve as chemical defence compounds against herbivores or infection, or they are involved in other types of interactions with different organisms (such as attraction of pollinators or allelopathy).
Secondary metabolites display great chemical diversity and are represented by many different classes of compounds, such as alkaloids, terpenes, flavonoids and a range of glycosides with different aglycone (non-sugar) moieties, such as cyanogenic glycosides, mustard oil glycosides (glucosinolates) and salicylate glycosides.Humans have a long and intimate relationship with natural products, not least in the form of medicinal agents, and more than 90% of therapeutic classes of drugs are derived from a natural product prototype. Microorganisms have yielded many important antibiotics, and fish and other marine organisms are the source of fatty acids with important health benefits. Plants have provided humans with medicines for millennia, and many modern drugs are still plant derived, such as opioids (incl. morphine and codeine), anti-cancer agents such as paclitaxel (Taxol®) and vincristine, and galanthamine, which is used for the treatment of Alzheimer's disease.
Forest Research and Genetics
Forest research at SCPS encompasses aspects of environmental, ecological and evolutionary genetics, of economically important subtropical forest trees.
A unifying feature of this research has been the characterisation of patterns of neutral and adaptive genetic variation in natural and planted tree populations, and the identification of influential natural and anthropogenic factors to inform natural resource management and tree improvement. Research has a strong pre-breeding emphasis, aimed at providing an understanding of genetics of adaptive traits that may be of economic significance in the establishment, propagation, and resilience of forest trees, and the quality of their products.
Located at Lismore, at the confluence of several major bioregions, and with its world class genomics and plant chemistry facilities, SCPS is ideally placed for the study of genetic and chemical diversity of a number of the subtropical eucalypts and other native trees of Australian and international significance, including, Eucalyptus grandis, Eucalyptus pilularis, and spotted gum (Corymbia citriodora). Our research has also included other natives, E. cloeziana, the Red Mahogany group, Tea Tree (Melaleuca alternifolia), native pine (Araucaria cunninghamii), as well as exotic Pinus hybrids.
- Tea Tree (Melaleuca alternifolia) root systems
- Corymbia genome project
- Population structure and species delineation of Blackbutts
- Gene pool management of Corymbia
- Genetics of adaptive traits and pre-breeding of tree crops | <urn:uuid:5239a899-e57e-404d-bfe7-4d5d94d1f943> | 3.25 | 1,638 | About (Org.) | Science & Tech. | 7.860936 | 95,523,479 |
Quantum mechanics, invisibility cloaks and water on Mars: The biggest scientific breakthroughs of the past decade
The world's first 'quantum machine' - a device that moves according to laws that govern the subatomic world - has been named as the biggest scientific breakthrough of the year.
The machine topped the list of the most significant developments in science in 2010 along with the sequencing of Neanderthal DNA, advances in HIV prevention and the synthetic genome.
Science magazine, one of the world's leading research journals, also came up with a list of the top 10 scientific achievements of the decade which includes the discovery of 'clear evidence' of past water on Mars and huge advances in the search for other planets.
Chromosomes under an electron microscope as part of genome research, left, while astronomers using the Hubble space telescope made even further breakthroughs in the search for dark matter, right
Created by US scientists at the University of California, Santa Barbara, the quantum machine consists of a tiny metal paddle invisible to the naked eye that dances to a quantum rhythm.
After first cooling the paddle to the lowest possible energy state, the researchers coaxed it into a purely quantum mechanical state of motion.
This meant it behaved in strange ways not seen in the 'macro' world of classical mechanics.
For instance, the device could be in two states at once - known as 'superpositions' - so that it vibrated a little and a lot at the same time.
The achievement by a team led by physicists Andrew Cleland and John Martinis was singled out as the most impressive advance of 2010 by Science, 'This year's Breakthrough of the Year represents the first time that scientists have demonstrated quantum effects in the motion of a human man-made object,' said Science writer Adrian Cho.
'On a conceptual level that's cool because it extends quantum mechanics into a whole new realm. On a practical level, it opens up a variety of possibilities ranging from new experiments that meld quantum control over light, electrical currents and motion to, perhaps someday, tests of the bounds of quantum mechanics and our sense of reality.'
The 10 ‘Insights of the Decade’: the insights that have changed the face of science since the dawn of the new millennium
Precision Cosmology: Over the past decade, researchers have deduced a very precise recipe for the content of the universe, which consists of 4 per cent ordinary matter, 23 per cent dark matter and 73 per cent dark energy; as well as instructions for putting it all together.
These advances have transformed cosmology into a precision science with a standard theory that now leaves very little room for other ideas.
Metamaterials: By synthesising materials with unconventional optical properties, physicists have pioneered new ways to guide and manipulate light, creating lenses that defy the fundamental limits on resolution. They've even begun constructing Harry Potter-style "cloaks" that can make an object invisible.
A photo of the 'metamaterial' cloak, right, which was able to bend microwaves. The breakthrough in metamaterials could one day pave the way to a Harry Potter style invisibility cloak
The ‘Dark’ Genome: Scientists discovered that genes account for just 1.5 percent of the whole. The rest of the genome, including small coding and non-coding RNAs is proving to be just as important as the genes.
Exoplanets: In the year 2000, researchers were aware of just 26 planets outside our solar system. By 2010, that number had jumped to 502—and still counting. Astronomers now expect to find many more Earth-like planets in the universe as better technology becomes available.
For now, the sizes and orbits of larger planets already discovered are revolutionising scientists' understanding of how planetary systems form and evolve.
Ancient Biomolecules: The realisation that 'biomolecules' like ancient DNA and collagen can survive for tens of thousands of years and provide important information about long-dead plants, animals and humans has been a huge breakthrough for paleontology.
Analysis of these tiny time machines can now reveal anatomical adaptations that skeletal evidence simply can't provide, such as the colour of a dinosaur's feathers or how woolly mammoths withstood the cold.
Astronomers discovered Earth-like planets orbiting a distant star, Gliese
Water on Mars: Half a dozen missions to Mars over the past decade have provided clear evidence that the Red Planet once harboured enough water—either on it or just inside it—to alter rock formations and, possibly, sustain life.
This Martian water was probably present around the time that life was beginning to appear on Earth, but there is still enough moisture on Mars today to encourage scientists seeking living, breathing microbes.
Reprogramming Cells: During the past decade, the notion that development is a one-way street has been turned on its head. Now, researchers have figured out how to "reprogram" fully developed cells into so-called pluripotent cells that regain their potential to become any type of cell in the body.
This technique has already been used to make cell lines from patients with rare diseases, but ultimately, scientists hope to grow genetically matched replacement cells, tissues and organs.
The Microbiome: A major shift in the way we view the microbes and viruses that call the human body home has led researchers to the concept of the microbiome—or the collective genomes of the host and the other creatures that live on or inside it.
Since 90 percent of the cells in our bodies are actually microbial, scientists are beginning to understand how significantly microbial genes can affect how much energy we absorb from our foods and how our immune systems respond to infections.
A colour-enhanced image of the delta in Jezero Crater on Mars, which once held a lake taken by NASA's Mars Reconnaissance Orbiter in 2008
Inflammation: Not long ago, inflammation was known as the simple sidekick to our healing machinery, briefly setting in to help immune cells rebuild tissue damage caused by trauma or infection.
Today, however, researchers believe that inflammation is also a driving force behind the chronic diseases that will eventually kill nearly all of us, including cancer, Alzheimer's disease, atherosclerosis, diabetes and obesity.
Climate Change: Researchers have found that many of their predictions about climate change in terms of temperature changes have been correct this decade, according to Science.
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Physics Pressure MCQs Quiz Online PDF Download
Practice physics pressure MCQs, A level physics test for online courses learning and test prep. Ideal gas quiz has multiple choice questions (MCQ), physics pressure quiz questions and answers to learn.
GCE physics practice test MCQ on surface area of a typical person is about with options 1 m², 2 m², 3 m² and 4 m² problem solving skills for viva, competitive exam prep, interview questions with answer key. Free study guide is for online learning physics pressure quiz with MCQs to practice test questions with answers.
MCQs on Physics Pressure Quiz PDF Download
MCQ. Surface area of a typical person is about
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MCQ. Force exerted on a person by atmosphere is
- 200 000 N
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- 500 000 N | <urn:uuid:6051ee74-6975-4e94-911d-3c20a6432d31> | 3.171875 | 199 | Product Page | Science & Tech. | 73.158243 | 95,523,484 |
The shell of planktonic foraminifera, varying in complexity, is one of the most commanding visual aspects of their morphology. Shell morphology has been a primary characteristic in taxonomic categorization of species. Recent fine structural studies of the cytoplasm and internal shell wall composition have largely complemented and substantiated the merit of using the shell architecture in establishing taxa. The remarkable regularity of shell design, species specific geometric plan, and the orderly manner of its development during maturation of the organisms also stimulates intriguing questions about the cellular biological basis for the genetic control of its deposition and the cytoplasmic mechanisms mediating its construction. Shells of planktonic foraminifera are one of the most abundant and significant calcitic fossil remains used extensively in interpreting biostratigraphic facies, reconstructing ancient environments based on fossil evidence, and providing evidence for major climatic changes in geological time (e.g. CLIMAP, 1976). Consequently, a clear understanding of the biological processes involved in shell deposition and an elucidation of environmental factors influencing the form and chemical composition of the shell wall are of broad significance for micropaleontology, cognate disciplines in the earth sciences and in cellular biology.
KeywordsChamber Wall Benthic Foraminifera Pore Plate Planktonic Foraminifera Chamber Deposition
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Is 10K reasonable?
Heres another question, can we detect radio waves clearly 1000 light years away?
10 kilometers? I hope so!
On surface of the curved earth the horizon is on the order of 40-60km (this is what they use for military planning purposes at any rate). On a clear day you can see forever (good movie, not very practical unless you have a Hubble Telescope). The Sun is more than 100 million km (100 Gm) away and you see it every day. The stars you can see with your naked eye on a clear night are in some cases hundreds of thousand or even hundreds of millions of light years away, if not further.
It depends on how strong they are, but in principle, certainly.
Could we detect a technological species 1000 light years away, since we havent yet...is it safe to say there are no technological species 1000 from us?
Maybe - if they were transmitting enough...
No, it isn't safe to say that: We're not looking at the entire sky with radio telescopes all the time and random broadcasts would have to be extremely powerful for us to pick up at that distance.
You are very preoccupied with this issue....
Why would the broadcasts have to be powerful? They would have to be sent 1000 years ago for a civilization 1000 light years away, but radio waves generally don't become weaker as they travel through space.
I agree with Russ here. We have only been leaking/sending signals for less than 100 years. So anyone 1000 light years away still has to wait 900 years until the signals arrive. There may be other factors involved too like maybe they don't want to be detected.
The radio waves lose intensity over distance as the photons spread out. The greater the distance the less photons you will receive.
Yes, very..its because on another forum, people are assuming that there are a very low number of technological species just because we havent detected anything in that 1000+ light-year sphere.
If they're older than us, then they are very likely far, far older, meaning that they very likely have discovered a more efficient means of communication than radio.
Who says? Maybe there at this very moment, at the exact same technological and societal level that we are at. Plus of course, the idea that they have discovered a better means of communication makes the assumption that a better means actually exists.
Well thats a bad basis for an assumption seeing as how the universe is like, 10839347187419273198237192873819273198231982738273124812749127481927498127418927419824 feet wide.
Hey i wonder what that jumble of numbers actually comes out to lol.
Oh not the whole universe, I meant just this galaxy...the Milky Way.
Oh well... still... pretty big :P
Well I do wish to be clear here. My understanding is the only stars we can see with the naked eye are those in our galaxy so that restricts us to about 100,000 light years and the only object outside our galaxy we can see with the naked eye is Andromeda which is 2 million light years away. Observational Astronomy is not my strong suite so if I'm wrong, please someone straighten me out.
I know you can see the Milky Way, which got me to 100,000. And, I know that there are galaxies you can see, which got me to a larger number.
I stand corrected on the hundreds of millions figure. This source: http://www.seds.org/messier/m/m033.html [Broken] puts the most distant at 3 million light years (M33) if your eyes are pretty normal, and 12 million light years (M81) if your eyes are exceptionally sharp. Andromeda would be the third most distant object visible to the naked eye. At least I was only off by about one order of magnitude.
So just because we havent heard anything or detected anything there still could be a technological civilization within 500-700 light years from ours?
I'll give you a fairly pedestrian counterexample.
Suppose that a technologically advanced civilization evolves on a planet we'll call Haze, which is a lot like we envisioned Venus would be before we actually got a chance to probe it -- 99%+ cloud covered, Earth like in temperature and gravity and atmosphere, and subject to frequently intense electrical storms.
First of all, astronomy might be a very late development relative to Earth, because people wouldn't even learn that there was anything other than cloud cover until they were sufficiently advanced to make rockets and high altitude aircraft (imagine Earth with no astronomy until the 1960s and there were only one or two telescopes in the entire history of the field). This would eliminate any reason to try to send radio waves into space.
Second of all, in an environment with a highly charged atmosphere, interference would be awful, especially for long range wireless applications like radio, so a civilization like this might very well have developed a purely landline based telecommunication system instead.
A civilization like that exactly contemporary with our own could exist on Alpha Centuri, just a few light years away, and we'd never know it. We don't even have the resolution to see a Venus like planet circling Alpha Centuri if there was one there. Hell, they could have a few space telescopes orbitting their planet and we'd still probably miss them if we sent at probe to Alpha Centuri and it spend a decade looking around the neighborhood. We wouldn't have any reason to know that there was life on Haze even then.
They could still be very advanced. They could have nuclear fusion power plants, a handful of small space ships that explored other planets in their system (and perhaps used a laser based communication protocol developed from the fibre optic systems used in their land lines). They could have amazing biotechnology. And, odds are that our probe would still miss them and all their artifacts and that their satellites and space ships would miss our probe.
"Second of all, in an environment with a highly charged atmosphere, interference would be awful, especially for long range wireless applications like radio."
Well I dont think thats how it is on our planet, is that even a possible planet?. I mean what are the chances of there being a civilization like that though? its like they are completely blocked from outer space.
There are five planets in the solar system with atmospheres too thick to see through (Venus and the Gas Giants). There is one with partial cloud cover (Earth). There are three planets that are never cloud covered (Mercury, Mars, Pluto). If I'm a Baysian, I say that the probability of a planet being cloud covered is 61% and the probability of a terrestrial planet being cloud covered is 30%. If you gave Earth a little more cloud cover (more like Venus) and adjusted the solar flux into its atmosphere a little by adjusting its distance from the Sun, you could get the same effect without being wretchedly hot like Venus is.
We can't gauge the odds in any meaningful way because we don't have a meaningful sample size. Someday we will. Some questions don't have answers. If I roll dice in a completely dark room and don't touch them, I can't know what number I've rolled.
Also, there are all sorts of other reasons why an advanced technological society might not make widespread use of radio. Maybe the rulers on another planet granted a 100 year monopoly on radio to an incompetent businessman and so landline infrastructure took off instead. Maybe people in that civilization are very privacy conscious and don't want people to be able to use electronic intelligence. It isn't a major leap. I personally almost never use either radio or broadcast television myself. I listen to radio via the internet primarily, because my home office is in a basement and reception isn't good in the office building where I work. In the car I prefer to listen to CDs. I don't want TV at all except for DVDs, but even if I did I would do it using coaxle cable which emits very little radio inteference. I don't own a cell phone. It would take only a slight adjustment in local economic incentives for any number of reasons to make a non-radio wave broadcast technology the norm. For solar system distance communications, you'd want narrow well focused beams of photons (a laser based system, for example), to minimize fall off in signal strength with distance, rather than omnidimensional transmissions.
There are lots of good reasons not to be looking or listening as well. How much support does SETI get here? Now, suppose that you're a highly advanced civilization and that from 1500-1900 AD you engaged in a massive project to identify every large object in the vicinity of your solar system, every star and galaxy in the sky, you figured out general relativity and dark matter and dark energy and what not, and you had such perfect data after the first 100 years that for the next 100 years your computer model and your observations were a perfect match, except for a handful of supernova which you could predict statistically and determine that they (and all the other things in deep space) were harmless to you. Suppose further that this was a frightfully expensive societal project because you kept having to repair instruments hit with micrometeroids and cosmic ray bursts. In 1900 AD, don't you think that your society, perhaps slightly different in psychology from our own, might decide that running nearly perfectly accurate computer models was good enough for future reference and stop looking for anything but supernova with a sensor tuned to detecting those (which would miss weak radio waves from Earth)? You'd feel vigilant yet economically efficient.
And I agree that radio isnt the only source of communication, there might be more efficient ways of communicating that these other technological civilizations are getting by with that we dont know about.
Oh and did you read my PM to you? please reply if you can, thanks.
One need only assume that a highly technological civilization might develop an environmental movement and you might not even be able to find traces in their atmosphere or much space junk.
Humans have discovered major new species of animals THIS YEAR, including whole ecosystems under the Arctic Shelf. And we've been prowling around this planet for ten thousand years since we learned how to read and write.
You bring up very good points, the more advanced the civilization is the less they waste, they become more efficient.
Thanks for clearing that up for me.
Separate names with a comma. | <urn:uuid:94609d2e-76e6-4bf6-b854-fda04e40abfb> | 2.8125 | 2,163 | Comment Section | Science & Tech. | 53.942304 | 95,523,495 |
The phenomenon of light emission by living organisms, bioluminescence, is quite common, especially in marine species. It is known that light is generated by chemical reactions in which oxygen molecules play an important part.
In the animal world, these chemical reactions take place in special luminescent cells called photocytes. These are aggregated into complex light organs, in which the intensity of light is regulated by nerve impulses, and in which light can be modulated with the help of reflectors, lenses and filters. By these means, organisms can adjust the wavelength, diffusion and intensity of light according to need. But the exact mechanisms behind these processes remain shrouded in mystery.
Jenny Krönström, a researcher at the Department of Zoology of the University of Gothenburg has put another piece of the jigsaw puzzle in place by investigating the light organs of marine jellyfish, crustaceans and fish. In her thesis she reveals that krill, the luminescent crustacean, is equipped with special muscles that regulate light intensity through contraction and relaxation.
Nitric oxide is also thought to play an important role in the bioluminescence of krill. It is produced in the small capillary vessels that keep the krill's photocytes supplied with oxygen, as well as in special closure muscles, sphincters, that are located at the point where these capillaries distribute blood to the photocytes. Experiments with agents that make the sphincters contract or relax show that when the sphincters relax, the krill begins to luminesce, presumably because of the increased flow of oxygenated blood to the photocytes.
As bioluminescence has developed independently at several different points in evolution, different species have developed different methods of regulating and emitting light. Jenny Krönström's research demonstrates that nitric oxide also has different effects in different species. In the remarkable deep sea Silver Hatchetfish (Argyropelecus olfersii) nitric oxide inhibits the light reaction, whilst in the Plain Midshipman fish (Porichthys notatus) it has an opposite, stimulating effect.
Biological light is not only useful to the organism itself as a biological torch, camouflage or as a means of communication; the substances that are involved in the chemical luminescent reaction have also shown themselves to be useful in modern molecular biology, in which the discovery of green fluorescent protein, which produces green light in jellyfish, led to the Nobel Prize in Chemistry as recently as 2008.
The thesis "Control of bioluminescence: Operating the light switch in photophores from marine animals" was defended on February 20th 2009.
Images: The Silver Hatchetfish (Argyropelecus olfersii) and "light-switch" muscles of the luminescent krill.For further information, please contact:
Krister Svahn | idw
Further reports about: > Argyropelecus > Argyropelecus olfersii > Hatchetfish > Plain Midshipman fish > Porichthys notatus > Silver Hatchetfish > Zoology > bioluminescence > chemical reaction > chemical reactions > fluorescent protein > living organisms > luminescent crustacean > marine animals > marine jellyfish > marine luminescence > marine species > nerve impulses > nitric oxide > oxygen molecules > phenomenon of light emission > photocytes
O2 stable hydrogenases for applications
23.07.2018 | Max-Planck-Institut für Chemische Energiekonversion
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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A chemical switch that modifies proteins contributes to diversity among life forms
Living things have long used a previously unrecognized method for diversifying and evolving. This strategy, as reported this week in Science, could account for some of the variation seen across species.
Phenotypic diversity and evolution in yeast species (grey and red) are shown. Mass spectrometry (a representative spectrum is shown in green) was used to identify thousands of phosphorylation sites on 18 yeast species, and phylogenetic approaches traced the evolutionary history of those sites across the yeast lineage.
Credit: Villen Lab/University of Washington
The work was led by the labs of Pedro Beltrao of the European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI) in the United Kingdom, and UW Medicine researcher Judit Villen, assistant professor of genome sciences at the University of Washington School of Medicine.
They worked with the labs of Maitreya Dunham, UW associate professor of genome sciences, and of Francesc Posas and Eulalia de Nadal of Universitat Pompeu Fabra in Spain as additional collaborators.
"This study is about understanding how evolution works, which tells you how species adapt to changing environments over many generations," said Beltrao in a news release on the paper from EMBL-EBI.
Most studies of evolution examine differences in the DNA or genome, but there are many implications of these differences that are not obvious by just looking at the DNA.
"For example," he said, "when you compare humans and chimps, they are obviously different, even though a good part of their genetic makeup is more or less the same. Our task is to figure out how diversity is generated, so that we can see in detail how life evolves."
The genome contains the instructions for making proteins, the machines and building blocks of life. These proteins are frequently modified after their production to regulate their biological function and other characteristics.
This mechanism offers an avenue to expand functional diversity beyond the sequences encoded by the DNA.
The researchers concentrated on a particular protein modification called phosphorylation.
"Phosphorylation is important to regulate protein function and to respond to changing environments," explained Villen, "so we thought new phosphorylation sites could be created during evolution to allow species to occupy new niches and adapt their metabolism to exploit available nutrients."
In their work, Villen and her collaborators traced the evolutionary history of thousands of phosphorylation sites on proteins across 18 yeast species. These are single-cell eukaryotic microorganisms that originated hundreds of millions of years ago.
Eukaryotes are living things whose cells contain a membrane-surrounded nucleus and whose DNA is housed in chromosomes. Human cells, too, are eukaryotic.
Existing knowledge about the origins and evolutionary history of yeast and their DNA sequences, along with recent developments in phosphoproteomics -- identifying and cataloging proteins modified by phosphate -- enabled the researchers to approach this project.
"Until recently," Villen said, "the technology was not ready to study phosphorylation at such depth or for so many samples. Now these experiments are much easier. In fact, a team of three very talented undergraduate students conducted most of the initial phosphoproteomic experiments for this project."
The authors found that only a small fraction of phosphosites -- locations on a protein molecule that can be phosphorylated -- remain conserved across the hundreds of millions of years that separate the various yeast species under study. Additional research on these few ancient sites suggests that the older sites are more likely to be functionally important, compared to those most recently acquired.
"Many young sites have also been found to be functional, and the fact that most of the sites are relatively new acquisitions shows the rapid scale of evolution of phosphorylation," Villen explained.
The researchers thought that the rapid evolution of phosphorylation could contribute strongly to the development of diverse characteristics observed across species or allow for new species to arise. This is analogous to what happens in cancer, where changes to cellular signaling and protein phosphorylation can alter what a cell looks like, as well as its metabolism, proliferation and migration properties.
Further analysis and comparisons of the yeast protein phosphosites revealed significant differences in phosphorylation motif preferences across species. Motifs are distinctive patterns around the site.
"This suggests that the proteins responsible for those phosphorylation events have changed in some way, either in abundance, specificity, or activity,'' Villen explained.
"On the whole, our results showed that the evolution of phospho-regulation is highly dynamic," the researchers concluded.
Changes in the regulation of proteins by such modifications, according to the scientists, have the capacity to quickly generate a diversity of solutions to conditions faced by organisms during evolution.
The research was supported by an Ellison Medical Foundation Award, an Amgen scholarship, a Mary Gates scholarship, a National Science Foundation grant, a Human Frontier Science Program award, a European Research Council grant, and several Spanish and Catalan government awards.
The title of the Science article is, "Evolution of protein phosphorylation across 18 fungal species."
Leila Gray | EurekAlert!
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
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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...
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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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Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
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Species Detail - Franklin's Gull (Larus pipixcan) - Species information displayed is based on all datasets.
Terrestrial Map - 10kmDistribution of the number of records recorded within each 10km grid square (ITM).
Marine Map - 50kmDistribution of the number of records recorded within each 50km grid square (WGS84).
11 January (recorded in 1999)
22 December (recorded in 2005)
National Biodiversity Data Centre, Ireland, Franklin's Gull (Larus pipixcan), accessed 22 July 2018, <https://maps.biodiversityireland.ie/Species/10158> | <urn:uuid:47072eb8-5da2-442b-b50d-7a1c620b956f> | 2.6875 | 137 | Structured Data | Science & Tech. | 44.97 | 95,523,604 |
Principles of Measuring Mechanical Quantities: Transduction of Deformation
This chapter deals with the problem of the transfer of a deformation in a mechanical construction by an external load to an electrical signal. This is called “transduction”. The most important mechanisms for transduction of mechanical microsensors use the following effects: piezoresistivity, the dependency of the capacity on the geometric arrangement of conductors, piezoelectricity, optical resonance and optical interferometry. We concentrate here on the first two, most important, transducers. For flowsensors the thermal domain is of great importance, but we shall defer the discussion of transducers using heat to the chapter on flowsensors.
KeywordsSpring Constant Gauge Factor Neutral Plane Electrical Isolation Plate Separation
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U.S. scientists may have found a new way to produce clean energy by way of dirty water, according to a new study out Monday.
The engineers have developed a more efficient method to use microbes to harness electricity from wastewater.
They hope their technique could be used in wastewater treatment facilities and to break down organic pollutants in the “dead zones” of oceans and lakes where fertilizer runoff has depleted oxygen, suffocating marine life.
However, for now the team from Stanford University have started small, with a prototype about the size of a D-cell battery, consisting of two electrodes — one positive and one negative — plunged into a bottle of wastewater, filled with bacteria.
As the bacteria consume the organic material, the microbes cluster around the negative electrode, throwing off electrons, which are captured in turn by the positive electrode.
“We call it fishing for electrons,” said environmental engineer Craig Criddle, one of the lead authors of the study published this week in the Proceedings of the National Acadamy of Sciences (PNAS).
“You can see that the microbes make nanowires to dump off their excess electrons,” Criddle added.
Scientists have long known of microbes, dubbed exoelectrogenic, that live in airless environments and are capable of “breathing” oxide minerals, instead of oxygen, to generate energy.
Over the past dozen years, several research groups have tried different approaches for transforming these microbes into bio-generators — but it has proven difficult to harness this energy efficiently.
The researchers said their new model is simple, yet efficient, and can harness about 30 percent of the potential energy in the wastewater — about the same rate as commercially available solar panels.
There is far less energy potential available in wastewater than the sun’s rays, they concede, but say the process has an added benefit: it cleans the water. That means it could could be used to offset some of the energy currently being consumed to treat wastewater.
[Image: “Serious Clinician Studying Chemical Element In Laboratory” via Shutterstock] | <urn:uuid:c8044fdd-4874-4d0f-a0dd-75addf343652> | 4.03125 | 430 | News Article | Science & Tech. | 22.8925 | 95,523,640 |
This section explains useful programming techniques for scheduling tasks.
The scheduler works best with tree-structured task graphs, because that is where the strategy of breadth-first theft and depth-first work applies very well. Also, tree-structured task graphs allow fast creation of many tasks. For example, if a master task tries to create
n children directly, it will take
O( steps. But with tree-structured forking, it takes only
O(log steps because some of the tasks created can go on to create subtasks.
Often, domains are not obviously tree-structured, but you can easily map them to trees. For example,
parallel_for works over an iteration space such as a sequence of integers. The template function
parallel_for uses that definition to recursively map the iteration space onto a binary tree.
spawn_and_wait_for_all method is a convenient way to wait for child tasks, but it incurs some inefficiency if a thread becomes idle. The idle thread attempts to keep busy by stealing tasks from other threads. The scheduler limits possible victim tasks to those deeper than the waiting task. This limit modifies the policy that the shallowest task should be chosen. The limit restrains memory demands in worst-case scenarios.
A way around the constraint is for the parent not to wait, but simply to spawn both children and return. The children are allocated not as children of the parent, but as children of the parent’s ... | <urn:uuid:07e87fd7-0e8e-4684-b03a-e05a2f013b7a> | 3.078125 | 313 | Documentation | Software Dev. | 54.897364 | 95,523,641 |
A transmission electron microscope is a microscope which transmits a beam of electrons through an ultra thin specimen, interacting with the specimen as it passes through. An image is formed from the interaction of the electrons transmitted through the specimen; the image is magnified and focused onto an imaging device, such as a fluorescent screen, on a layer of photographic film, or to be detected by a sensor such as a CCD camera.
Transmission electron microscopes use extremely thin (0.5 µm or less) samples illuminated by the electron beam. Images are recorded by detecting the electrons that pass though the sample to a system of electromagnetic lenses which focus and enlarge the image on the fluorescent screen, photographic film or digital camera. Magnifications beyond 1,000,000x are attainable with a transmission electron microscope. | <urn:uuid:8f7b8ea2-b919-47a9-a1ea-5b92f1e2a937> | 3.484375 | 161 | Knowledge Article | Science & Tech. | 29.210833 | 95,523,683 |
Trimethylaluminium is one of the simplest examples of an organoaluminium compound. Despite its name it has the formula Al2(CH3)6 (abbreviated as Al2Me6 or TMA) as it exists as a dimer. This colorless liquid is an industrially important compound but must be handled with care due to its pyrophoricity; it evolves white smoke (aluminium oxides) when the vapor is released into the air.
Trimethylaluminium; aluminium trimethyl; aluminium trimethyl
3D model (JSmol)
|Molar mass||144.17 g/mol|
72.09 g/mol (C3H9Al)
|Melting point||15 °C (59 °F; 288 K)|
|Boiling point||125–130 °C (257–266 °F; 398–403 K) |
Std enthalpy of
Gibbs free energy (ΔfG˚)
|GHS signal word||Danger|
|H250, H260, H314|
|P222, P223, P231+232, P280, P370+378, P422|
|Flash point||−17.0 °C (1.4 °F; 256.1 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Structure and bondingEdit
Al2Me6 exists mostly as a dimer at room temperature and pressure, analogous in structure and bonding to diborane. As with diborane, the molecules are connected by 2 3-center-2-electron bonds: the shared methyl groups bridge between the two aluminium atoms. The Al-C(terminal) and Al-C(bridging) distances are 1.97 and 2.14 Å, respectively. The carbon atoms of the bridging methyl groups are each surrounded by five neighbors: three hydrogen atoms and two aluminium atoms. The methyl groups interchange readily intramolecularly and intermolecularly.
3-Centered-2-electron bonds are an utterance of "electron-deficient" molecules and tend to undergo reactions with Lewis bases that would give products consisting of 2-centered-2-electron bonds. For example, upon treatment with amines gives adducts R3N-AlMe3. Another reaction that gives products that follow the octet rule is the reaction of Al2Me6 with aluminium trichloride to give (AlMe2Cl)2.
The monomer species AlMe3, which has an aluminium atom bonded to three methyl groups, occurs at high temperature and low pressure. VSEPR Theory predicts and electron diffraction confirms that it has a trigonal planar (threefold) symmetry, as observed in BMe3.
Synthesis and applicationsEdit
TMA is prepared via a two-step process that can be summarized as follows:
- 2 Al + 6 CH3Cl + 6 Na → Al2(CH3)6 + 6 NaCl
TMA is mainly used for the production of methylaluminoxane, an activator for Ziegler-Natta catalysts for olefin polymerisation. TMA is also employed as a methylation agent. Tebbe's reagent, which is used for the methylenation of esters and ketones, is prepared from TMA.
In combination with Cp2ZrCl2 (zirconocene dichloride), the (CH3)2Al-CH3 adds "across" alkynes to give vinyl aluminum species that are useful in organic synthesis in a reaction known as carboalumination.
Semiconductor grade TMAEdit
TMA is the preferred metalorganic source for metalorganic vapour phase epitaxy (MOVPE) of aluminium-containing compound semiconductors, such as AlAs, AlN, AlP, AlSb, AlGaAs, AlInGaAs, AlInGaP, AlGaN, AlInGaN, AlInGaNP, etc. Criteria for TMA quality focus on (a) elemental impurities, (b) oxygenated and organic impurities.
- Sigma-Aldrich Co., Trimethylaluminum. Retrieved on 2014-05-05.
- Carlsson, J.; Gorbatkin, S.; Lubben, D.; Greene, J. E. (1991). "Thermodynamics of the homogeneous and heterogeneous decomposition of trimethylaluminum, monomethylaluminum, and dimethylaluminumhydride: Effects of scavengers and ultraviolet-laser photolysis". Journal of Vacuum Science and Technology B. 9 (6): 2759–2770. doi:10.1116/1.585642.
- Holleman, A. F.; Wiberg, E. (2001). Inorganic Chemistry. San Diego: Academic Press. ISBN 0-12-352651-5.
- Almennin, A.; Halvorse, S.; Haaland, A. (2005). "Gas Phase Electron Diffraction Investigation of Molecular Structures of Trimethylaluminum Monomer and Dimer". Acta Chemica Scandinavica. 44 (15): 2232–2234. doi:10.3891/acta.chem.scand.25-1937.
- Biswas, K.; Prieto, O.; Goldsmith, P. J.; Woodward, S. (2005). "Remarkably Stable (Me3Al)2 · DABCO and Stereoselective Nickel-Catalyzed AlR3 (R = Me, Et) Additions to Aldehydes". Angewandte Chemie International Edition. 44 (15): 2232–2234. doi:10.1002/anie.200462569. PMID 15768433.
- Negishi, E.; Matsushita, H. (1984). "Palladium-Catalyzed Synthesis of 1,4-Dienes by Allylation of Alkenyalane: α-Farnesene [1,3,6,10-Dodecatetraene, 3,7,11-trimethyl-]". Organic Syntheses. 62: 31.; Collective Volume, 7, p. 245 | <urn:uuid:8b834e79-2abf-4ddd-a8ab-80bd149b1bf8> | 2.84375 | 1,366 | Knowledge Article | Science & Tech. | 55.739212 | 95,523,719 |
Weizmann Institute scientists have devised a unique new mechanism for the formation of hydrogen and oxygen from water, without the need for sacrificial chemical agents, through individual steps, using light.
The design of efficient systems for splitting water into hydrogen and oxygen, driven by sunlight is among the most important challenges facing science today, underpinning the long term potential of hydrogen as a clean, sustainable fuel. But man-made systems that exist today are very inefficient and often require additional use of sacrificial chemical agents. In this context, it is important to establish new mechanisms by which water splitting can take place.
Now, a unique approach developed by Prof. David Milstein and colleagues of the Weizmann Institute's Organic Chemistry Department, provides important steps in overcoming this challenge. During this work, the team demonstrated a new mode of bond generation between oxygen atoms and even defined the mechanism by which it takes place. In fact, it is the generation of oxygen gas by the formation of a bond between two oxygen atoms originating from water molecules that proves to be the bottleneck in the water splitting process. Their results have recently been published in Science.
Nature, by taking a different path, has evolved a very efficient process: photosynthesis - carried out by plants - the source of all oxygen on Earth. Although there has been significant progress towards the understanding of photosynthesis, just how this system functions remains unclear; vast worldwide efforts have been devoted to the development of artificial photosynthetic systems based on metal complexes that serve as catalysts, with little success. (A catalyst is a substance that is able to increase the rate of a chemical reaction without getting used up.)
The new approach that the Weizmann team has recently devised is divided into a sequence of reactions, which leads to the liberation of hydrogen and oxygen in consecutive thermal- and light-driven steps, mediated by a unique ingredient - a special metal complex that Milstein's team designed in previous studies. Moreover, the one that they designed - a metal complex of the element ruthenium - is a 'smart' complex in which the metal center and the organic part attached to it cooperate in the cleavage of the water molecule.
The team found that upon mixing this complex with water the bonds between the hydrogen and oxygen atoms break, with one hydrogen atom ending up binding to its organic part, while the remaining hydrogen and oxygen atoms (OH group) bind to its metal center.
This modified version of the complex provides the basis for the next stage of the process: the 'heat stage.' When the water solution is heated to 100?C hydrogen gas is released from the complex - a potential source of clean fuel - and another OH group is added to the metal center.
'But the most interesting part is the third 'light stage,'' says Milstein. 'When we exposed this third complex to light at room temperature, not only was oxygen gas produced, but the metal complex also reverted back to its original state, which could be recycled for use in further reactions.'
These results are even more remarkable considering that the generation of a bond between two oxygen atoms promoted by a man-made metal complex is a very rare event, and it has been unclear how it can take place. Yet Milstein and his team have also succeeded in identifying an unprecedented mechanism for such a process. Additional experiments have indicated that during the third stage, light provides the energy required to cause the two OH groups to get together to form hydrogen peroxide (H2O2), which quickly breaks up into oxygen and water. 'Because hydrogen peroxide is considered a relatively unstable molecule, scientists have always disregarded this step, deeming it implausible; but we have shown otherwise,' says Milstein. Moreover, the team has provided evidence showing that the bond between the two oxygen atoms is generated within a single molecule - not between oxygen atoms residing on separate molecules, as commonly believed - and it comes from a single metal center.
Discovery of an efficient artificial catalyst for the sunlight-driven splitting of water into oxygen and hydrogen is a major goal of renewable clean energy research. So far, Milstein's team has demonstrated a mechanism for the formation of hydrogen and oxygen from water, without the need for sacrificial chemical agents, through individual steps, using light. For their next study, they plan to combine these stages to create an efficient catalytic system, bringing those in the field of alternative energy an important step closer to realizing this goal.
Participating in the research were former postdoctoral student Stephan Kohl, Ph.D. student Leonid Schwartsburd and technician Yehoshoa Ben-David all of the Organic Chemistry Department, together with staff scientists Lev Weiner, Leonid Konstantinovski, Linda Shimon and Mark Iron of the Chemical Research Support Department.
Prof. David Milstein's research is supported by the Mary and Tom Beck-Canadian Center for Alternative Energy Research; and the Helen and Martin Kimmel Center for Molecular Design. Prof. Milstein is the incumbent of the Israel Matz Professorial Chair of Organic Chemistry.
The Weizmann Institute of Science in Rehovot, Israel, is one of the world's top-ranking multidisciplinary research institutions. Noted for its wide-ranging exploration of the natural and exact sciences, the Institute is home to 2,600 scientists, students, technicians and supporting staff. Institute research efforts include the search for new ways of fighting disease and hunger, examining leading questions in mathematics and computer science, probing the physics of matter and the universe, creating novel materials and developing new strategies for protecting the environment.
Yivsam Azgad | idw
Further reports about: > H2O2 > Hydrogen > Oxygen > Science TV > artificial catalyst > chemical agents > hydrogen peroxide > oxygen atom > oxygen atoms > oxygen gas > photosynthesis > renewable clean energy research > sacrificial chemical agents > sunlight-driven splitting of water into oxygen and hydrogen > water molecules > water splitting process
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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Status: Not Listed
The burrowing owl is a ground-dwelling bird species. This owl's characteristics include long legs, a brown body with speckles of white, and the absence of ear tufts. Both males and females stand about 10 inches (25 centimeters) tall and weigh six ounces (170 grams). The burrowing owl's wingspan is 20 to 24 inches (51 to 61 centimeters).
Summer breeding populations of burrowing owls can be found from the Midwest to the eastern parts of the Pacific states and into Canada. Winter populations are found in Central America and Mexico. Burrowing owls can be seen year-round in Florida, Mexico, and parts of South America, excluding the Amazon rain forest. Burrowing owls live in burrows dug by other animals in open, treeless spaces. In the U.S. they are most abundant in the burrows of various prairie dog species.
Burrowing owls eat insects, small mammals, amphibians, reptiles, and other birds, depending on the season and food availability. They are most active at dawn and dusk, but some owls hunt during both day and night. Insects are more often caught during the day, and more mammals are consumed at night.
The burrowing owl may dig its own nest or utilize the abandoned burrows of prairie dogs, armadillos, skunks, or pocket gophers. Both parents take care of their young until they are ready to leave the nest, about 40 days after hatching. The owlets are able to scare away predators by hiding in the burrow and mimicking the sounds of a rattlesnake. A burrowing owl's average lifespan is six to eight years.
Populations of burrowing owls are declining in some areas due to pesticide use, poisoning of prairie dog colonies, and automobile collisions. Conservation concerns differ by region, and in various states they are listed as endangered, threatened, or as a species of concern. They also are of conservation concern in Canada and Mexico.
Burrowing owls collect mammal waste that they put around their nests to attract dung beetles, one of their favorite foods.
Animal Diversity Web, University of Michigan Museum of Zoology
Burrowing Owl Conservation Network
The Cornell Lab of Ornithology
The Institute of Bird Populations
Place your order today for the themed box that delivers everything you need to create family memories while discovering nature and wildlife.Read More
Find out what it means to source wood sustainably, and see how your favorite furniture brands rank based on their wood sourcing policies, goals, and practices.Read More
Climate change is allowing ticks to survive in greater numbers and expand their range—influencing the survival of their hosts and the bacteria that cause the diseases they carry.Read More
Tell your members of Congress to save America's vulnerable wildlife by supporting the Recovering America's Wildlife Act.Read More
You don't have to travel far to join us for an event. Attend an upcoming event with one of our regional centers or affiliates. | <urn:uuid:a736958c-3568-407f-a04f-463f8344b71a> | 3.65625 | 624 | Knowledge Article | Science & Tech. | 44.734541 | 95,523,725 |
Scientists have developed a light-based measuring technique that could transform our ability to characterize biomolecules.
Using a microscope that detects light scattering rather than fluorescence, the researchers have demonstrated that single molecules can be observed, and their mass measured, in solution, is reported in the journal Science.
'Single molecules have been observed in light microscopes since the late 1980s, but essentially all optical techniques rely on fluorescence, which is the emission of light by a material after being "excited" by the absorption of electromagnetic radiation. As immensely powerful as that is, it is not universal.'
The researchers first demonstrated the use of light scattering to visualize individual proteins - biomolecules only a few nanometres across - in 2014. But it was not until last year that they were able to improve the image quality sufficiently to compete with fluorescence.
The senior author said: 'We then addressed the question of whether we could use our visualization approach to quantify, rather than just detect, single molecules. We realized, given that the volume and optical properties of biomolecules scale directly with mass, that our microscope should be mass sensitive. This turned out indeed to be the case, not only for proteins but also for molecules containing lipids and carbohydrates.'
Using interferometric scattering microscopy to quantify the mass of single biomolecules in solution with 2% sequence mass accuracy, up to 19-kilodalton resolution, and 1-kilodalton precision. We resolved oligomeric distributions at high dynamic range, detected small-molecule binding, and mass-imaged proteins with associated lipids and sugars. These capabilities enabled us to characterize the molecular dynamics of processes as diverse as glycoprotein cross-linking, amyloidogenic protein aggregation, and actin polymerization.
It is this generality that excites the authors. The co-author of the work, said: 'The beauty of mass is that it is both a universal property of matter and extremely diagnostic of the molecule under investigation. Our approach is therefore broadly applicable and, unlike traditional single-molecule microscopy, does not rely on the addition of labels to make molecules visible.'
The researchers say the technique - which they call interferometric scattering mass spectrometry (iSCAMS) - could have applications ranging from studies of protein-protein interactions to drug discovery and even point-of-care diagnostics.
Because essentially every physiological and pathological process is controlled by biomolecular interactions in solution, the researchers say this technology has considerable potential impact. The team is in the process of commercializing the technology to provide access to other researchers who are not experts or may not even use optical microscopy. The researchers say: 'It has the potential, we think, to revolutionise how we study biomolecul es and their interactions.'
Weighing proteins with light!
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Authors: Peter V. Raktoe
The formula E=mc2, which states that the energy content of a massive object is equal to that object's mass times the speed of light squared, is incorrect. Why?, because that formula implies that a mass requires an infinite amount of energy to reach the speed of light. The term "infinite" is often used by physicists but they don't seem to realize that it's unrealistic/unnatural, it tells us that E=mc2 is a mistake and I can explain why.
Comments: 2 Pages.
Unique-IP document downloads: 89 times
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Synthetic geometry differs from other branches of geometry because it focuses on pure geometrical contents and draws conclusions through the use of axioms, logical arguments and theorems. Synthetic geometry analyzes the incidence relationship between objects such as lines and planes. These objects and their relationship of incidence are known as the primitives of synthetic geometry.
Axiomatic geometry is sometimes used interchangeably with the term synthetic geometry. In mathematics, the concept of an axiom is critical to the study of Euclidean geometry. Axioms are statements which are used to describe and prove the primitives of synthetic geometry. Essentially, these are just basic statements which have not yet been accepted or proven. For example, the statement “for any two distinct points, there is only one line which passes through both of these points”, is an axiom.
In conjunction with axioms, theorems are used in synthetic geometry. Theorems differ from axioms because they represent proven statements. Theorems can be proven by axioms which are thought to be accepted or by other theorems which exist. In order to formulate conclusions regarding mathematical problems and conduct geometric computations, theorems are utilized in synthetic geometry. Furthermore, logical arguments are used as a mode of proof through persuasion.
Evidently, synthetic geometry is one of the many distinct branches of geometry, just like analytic and algebraic geometry, which is used to understand geometrical structures. Thus, understanding the proper use of axioms, logical arguments and theorems is essential to this field of thought.© BrainMass Inc. brainmass.com July 15, 2018, 3:54 pm ad1c9bdddf | <urn:uuid:eb2b049d-fc89-47a1-8866-666c4d6f2b32> | 4 | 351 | Knowledge Article | Science & Tech. | 27.718235 | 95,523,755 |
Hexagon - MO
The picture shows the ABCD square, the EFGD square and the HIJD rectangle. Points J and G lie on the side CD and is true |DJ| <|DG| and the points H and E lie on the DA side, with the |DH| < |DE|. We also know that |DJ| = |GC|. The hexagon ABCGFE has a perimeter 96 cm and hexagon EFGJIH having a perimeter 60 cm and a rectangle HIJD have perimeter 28 cm. Find the area of the hexagon EFGJIH.
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Researchers from Princeton University have determined that climate models underestimate the cooling effect that clouds have on a daily basis, especially over land areas.
Climate models are a tool used by scientists to help project future climate conditions across the world.
The study found that climate models factor too much of the sun's daily heat, which likely results in warmer and drier model projections than what might actually occur.
The researchers analyzed satellite images from 1986-2005 to calculate average diurnal cycles of clouds in each season across the world. The researchers compared the averages that they came up with to those from 9 climate models used by climate scientists.
The good news is that these model inaccuracies did not seem to invalidate climate projections. However, they did increase the margin of error.
Key excerpts from the Princeton report...........
"These errors can trickle down into other changes, such as projecting fewer and weaker storms. We hope that our results are useful for improving how clouds are modeled, which would improve the calibration of climate models and make the results much more reliable," said co-author Amilcare Porporato, a professor of civil and environmental engineering at the Princeton Environmental Institute.
"louds change during the day and from day to day. Climate models do a good job of capturing the average cloud coverage, said lead-author Jun Yin, but they miss important peaks in actual cloud coverage. These peaks can have a dramatic effect on daily conditions, such as in the early afternoon during the hottest part of the day.
"Climate scientists have the clouds, but they miss the timing," Porporato said. "There's a strong sensitivity between the daily cloud cycle and temperature. It's like a person putting on a blanket at night or using a parasol during the day. If you miss that, it makes a huge difference."
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Data indicates that there has been a slight downward trend in the annual maximum extent of Great Lakes ice cover since the 1970s.
A new study concludes that global warming may eventually be twice as warm as what current climate model consensus indicates.
The increased use of air conditioning in a warming world may lead to a significant degradation of air quality in the eastern U.S. by mid-century.
Dr. James Hansen's climate model projections from the 1980s have been mostly on target.
May 2018 and the spring of 2018 both ranked in the top five warmest on record.
Rate of ice loss in Antarctica has tripled over the past decade.
A combination of a warming climate climate and increased urbanization (heat island effect) has caused a 25 to 50 percent decrease in low cloud cover in the greater Los Angeles area since the 1970s. | <urn:uuid:e8b3ce1f-363a-47bd-8bcb-ea638addd2df> | 3.90625 | 581 | Content Listing | Science & Tech. | 47.543675 | 95,523,801 |
EGS-zs8-1 viewed by the Hubble Space Telescope
|Observation data (J2000 epoch)|
|Right ascension||14h 20m 34.89s|
|Declination||+53° 00′ 15.4″|
|Distance||4 Gpc (13×109 ly)|
|Size||15,000 ly (diameter)|
EGS-zs8-1 is a high-redshift Lyman-break galaxy found at the northern constellation of Boötes. In May 2015, EGS-zs8-1 had the highest spectroscopic redshift of any known galaxy, meaning EGS-zs8-1 was the most distant and the oldest galaxy observed. In July 2015, EGS-zs8-1 was surpassed by EGSY8p7 (EGSY-2008532660)
The redshift of EGS-zs8-1 was measured at z = 7.73, corresponding to a light travel distance of about 13.04 billion light years from Earth, and age of 13.04 billion years. The galaxy shows a high rate of star formation, so it releases its peak radiation at the vacuum ultraviolet part of the electromagnetic spectrum, near the 121.567 nm (1,215.67 Å) Lyman-alpha emission line due to the intense radiation from newly formed blue stars, hence it is classified as a Lyman-break galaxy; high-redshift starburst galaxies emitting the Lyman-alpha emission line. Because of the cosmological redshift effect caused by the metric expansion of space, the peak light from the galaxy has become redshifted and has moved into the infrared part of the electromagnetic spectrum. The galaxy has a comoving distance (light travel distance multiplied by the Hubble constant, caused by the metric expansion of space) of about 30 billion light years from Earth.
EGS-zs8-1 was born 670 million years after the Big Bang, during the period of reionization, and it's 15 percent the size of the Milky Way. The galaxy was found to be larger than its other neighbors in that period when the universe was still very young. Its mass at the time the light was emitted is estimated to have been about 15% of the Milky Way's current mass. The galaxy was making new stars at roughly 80 times the rate of the current Milky Way, or equivalent to 800 M☉ worth of material turning to stars every year. The light reaching Earth was made by stars in EGS-zs8-1 that were 100 million to 300 million years old at the time they emitted the light. The age of EGS-zs8-1 places it in the reionization phase of creation, a time when hydrogen outside the galaxies was switching from a neutral to ionized state. According to the galaxy's discoverers, EGS-zs8-1 and other early galaxies were likely the causes of reionization.
In 2013, Yale astronomer Pascal Oesch spotted an unexpected bright object while looking at Hubble Space Telescope images. He then confirmed the existence of the object using the Spitzer Space Telescope. Redshift calculations, using the Multi-Object Spectrometer for Infrared Exploration (MOSFIRE) equipment at the W.M. Keck Observatory in Hawaii, were then performed to precisely determine the age of the galaxy. Oesch and his colleagues at Yale and the University of California, Santa Cruz announced the find, which was named EGS-zs8-1, in May 2015 surpassing the previous record for oldest galaxy by about 30 million years.
Z8 GND 5296
| Most distant galaxy
- "Astronomers Set a New Galaxy Distance Record - Fast Facts". HubbleSite. 5 May 2015. STScI-2015-22. Retrieved 9 May 2015.
- Oesch, P.A.; et al. (3 May 2015). "A Spectroscopic Redshift Measurement for a Luminous Lyman Break Galaxy at z=7.730 using Keck/MOSFIRE". The Astrophysical Journal. 804: L30. arXiv: . Bibcode:2015ApJ...804L..30O. doi:10.1088/2041-8205/804/2/L30.
- Villard, Ray; Chou, Felicia (5 May 2015). "Astronomers Set a New Galaxy Distance Record". HubbleSite. Retrieved 7 May 2015.
- Borenstein, Seth (5 May 2015). "Astronomers find farthest galaxy: 13.1 billion light-years". AP News. Retrieved 6 May 2015.
- Jonathan O'Callaghan & Ellie Zolfagharifard (16 July 2015). "A galaxy that rally IS far, far away: Astronomers confirm star system 13.1 billion light-years away is the most distant known in the universe". Daily Mail (London).
- Overbye, Dennis (5 May 2015). "Astronomers Measure Distance to Farthest Galaxy Yet". New York Times. Retrieved 6 May 2015.
- Cofield, Calla (5 May 2015). "This Galaxy Far, Far Away Is the Farthest One Yet Found". Space.com. Retrieved 7 May 2015.
- Staff (5 May 2015). "Astronomers unveil the farthest galaxy". Phys.org. Retrieved 6 May 2015.
- Lemonick, Michael D.; 06, National Geographic PUBLISHED May. "Farthest Galaxy Spotted Yet Is 13 Billion Light-Years Away". National Geographic News. Retrieved 2015-06-18. | <urn:uuid:bb595d48-2372-4519-880c-fbc6a2ea8bab> | 3.484375 | 1,170 | Knowledge Article | Science & Tech. | 72.286309 | 95,523,815 |
Viewing posts for the category IUCN
On May 21, 2014, the IUCN formally approved the categories and criteria for identifying and evaluating the risk of ecosystems. This year the Red List of Ecosystems (RLE) celebrates its 4th Anniversary.
Posted by: Provita in Conference, COP23, IUCN, RLE, UNFCCC - Nov. 30, 2017, 11:19 a.m.
The required governmental commitments to fight against climate change and uphold the Paris Agreement were being addressed during the UNFCCC COP23 in Bonn, Germany.
The IUCN hosts its first introductory RLE workshop in Switzerland!
Posted by: Provita in Conference, COP13, IUCN, UNCCD - Sept. 7, 2017, 2:25 p.m.
The required governmental commitments to fight against desertification will be addressed during the UNCCD COP13 in Mongolia, Republic of China.
Posted by: Provita in Colombia, IUCN, Publications, RLE - Aug. 29, 2017, 1:28 p.m.
The presentation of the Colombian Red List of Ecosystems –RLE (version 2.0) was held last August 16, led by Conservación Internacional, the Universidad Javeriana and the Humboldt Institute. | <urn:uuid:2b13bb71-dcb2-4133-9922-e39aadbf046e> | 2.765625 | 277 | Content Listing | Science & Tech. | 57.942734 | 95,523,869 |
A Visual Script node used to call built-in functions.
- MATH_SIN = 0 — Return the sine of the input.
- MATH_COS = 1 — Return the cosine of the input.
- MATH_TAN = 2 — Return the tangent of the input.
- MATH_SINH = 3 — Return the hyperbolic sine of the input.
- MATH_COSH = 4 — Return the hyperbolic cosine of the input.
- MATH_TANH = 5 — Return the hyperbolic tangent of the input.
- MATH_ASIN = 6 — Return the arc sine of the input.
- MATH_ACOS = 7 — Return the arc cosine of the input.
- MATH_ATAN = 8 — Return the arc tangent of the input.
- MATH_ATAN2 = 9 — Return the arc tangent of the input, using the signs of both parameters to determine the exact angle.
- MATH_SQRT = 10 — Return the square root of the input.
- MATH_FMOD = 11 — Return the remainder of one input divided by the other, using floating-point numbers.
- MATH_FPOSMOD = 12 — Return the positive remainder of one input divided by the other, using floating-point numbers.
- MATH_FLOOR = 13 — Return the input rounded down.
- MATH_CEIL = 14 — Return the input rounded up.
- MATH_ROUND = 15 — Return the input rounded to the nearest integer.
- MATH_ABS = 16 — Return the absolute value of the input.
- MATH_SIGN = 17 — Return the sign of the input, turning it into 1, -1, or 0. Useful to determine if the input is positive or negative.
- MATH_POW = 18 — Return the input raised to a given power.
- MATH_LOG = 19 — Return the natural logarithm of the input. Note that this is not the typical base-10 logarithm function calculators use.
- MATH_EXP = 20 — Return the mathematical constant e raised to the specified power of the input. e has an approximate value of 2.71828.
- MATH_ISNAN = 21 — Return whether the input is NaN (Not a Number) or not. NaN is usually produced by dividing 0 by 0, though other ways exist.
- MATH_ISINF = 22 — Return whether the input is an infinite floating-point number or not. Infinity is usually produced by dividing a number by 0, though other ways exist.
- MATH_EASE = 23 — Easing function, based on exponent. 0 is constant, 1 is linear, 0 to 1 is ease-in, 1+ is ease out. Negative values are in-out/out in.
- MATH_DECIMALS = 24 — Return the number of digit places after the decimal that the first non-zero digit occurs.
- MATH_STEPIFY = 25 — Return the input snapped to a given step.
- MATH_LERP = 26 — Return a number linearly interpolated between the first two inputs, based on the third input. Uses the formula
a + (a - b) * t.
- MATH_INVERSE_LERP = 27
- MATH_RANGE_LERP = 28
- MATH_DECTIME = 29 — Return the result of ‘value’ decreased by ‘step’ * ‘amount’.
- MATH_RANDOMIZE = 30 — Randomize the seed (or the internal state) of the random number generator. Current implementation reseeds using a number based on time.
- MATH_RAND = 31 — Return a random 32 bits integer value. To obtain a random value between 0 to N (where N is smaller than 2^32 - 1), you can use it with the remainder function.
- MATH_RANDF = 32 — Return a random floating-point value between 0 and 1. To obtain a random value between 0 to N, you can use it with multiplication.
- MATH_RANDOM = 33 — Return a random floating-point value between the two inputs.
- MATH_SEED = 34 — Set the seed for the random number generator.
- MATH_RANDSEED = 35 — Return a random value from the given seed, along with the new seed.
- MATH_DEG2RAD = 36 — Convert the input from degrees to radians.
- MATH_RAD2DEG = 37 — Convert the input from radians to degrees.
- MATH_LINEAR2DB = 38 — Convert the input from linear volume to decibel volume.
- MATH_DB2LINEAR = 39 — Convert the input from decibel volume to linear volume.
- MATH_POLAR2CARTESIAN = 40 — Converts a 2D point expressed in the polar coordinate system (a distance from the origin
rand an angle
th) to the cartesian coordinate system (x and y axis).
- MATH_CARTESIAN2POLAR = 41 — Converts a 2D point expressed in the cartesian coordinate system (x and y axis) to the polar coordinate system (a distance from the origin and an angle).
- MATH_WRAP = 42
- MATH_WRAPF = 43
- LOGIC_MAX = 44 — Return the greater of the two numbers, also known as their maximum.
- LOGIC_MIN = 45 — Return the lesser of the two numbers, also known as their minimum.
- LOGIC_CLAMP = 46 — Return the input clamped inside the given range, ensuring the result is never outside it. Equivalent to min(max(input, range_low), range_high)
- LOGIC_NEAREST_PO2 = 47 — Return the nearest power of 2 to the input.
- OBJ_WEAKREF = 48 — Create a WeakRef from the input.
- FUNC_FUNCREF = 49 — Create a FuncRef from the input.
- TYPE_CONVERT = 50 — Convert between types.
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Winful's argument against superluminality in the Hartman effect is supported by QED
QED converts the stored energy of non-propagating evanescent waves to photons that propagate through double prisms to the outside world thereby supporting Winful’s argument that superluminal velocities do not occur in the Hartman effect
The Hartman effect suggests superluminal velocities as the evanescent tunneling time tends to a constant for large barriers. With evanescent tunneling, the barrier may be the gap between double prisms as shown in the thumbnail. When the prisms are in contact, the light passes straight through, but when there is a gap, the light may either tunnel across or follow the refracted path. Since the time for light to travel across large gaps is found to be the same as for short gaps, the Hartman effect has been interpreted to suggest the photons have crossed the gap with superluminal velocity.
However, Winful argues non-propagating evanescent waves are virtual photons that do not propagate across the gap into the outside world. Since the velocity of non-propagating waves is meaningless, the light in the Hartman effect cannot travel at superluminal velocities, but rather only be delayed. Of course, if the delay in tunneling is interpreted as a transit time then the Hartman effect naturally leads to superluminal velocities.
On the other hand, if the delay in tunneling is the time for storing incident photon energy until the barrier can be breached, the Hartman effect may be explained by the saturation of incident photon energy in the barrier. The delay is then the time for the flux of incident photons to saturate before the barrier is breached. Because of this, Winful claims the Hartman effect is completely explained by the saturation of stored energy without the need for superluminal velocities. For an overview of the Hartman effect and Winful’s argument, see http://en.wikipedia.org/
The problem with Winful’s argument of the delayed time for stored energy of evanescent waves necessary to breach the barrier is the fact non-propagating evanescent waves cannot propagate irrespective of whether the stored energy can breach the barrier. What this means is tunneling of photons through the double prism gap occurs by a more fundamental mechanism that creates photons from stored energy that are indeed capable of propagating across the gap. Evanescent waves are not this mechanism, but rather are only a way of supplying EM energy of incident photons to the gap. EM stands for electromagnetic.
QED provides a way of creating photons from the stored EM energy of evanescent waves stored in the gap. QED stands for quantum electrodynamics. Simply put, QED creates photons if EM energy is supplied to a QED cavity, e.g., for a cavity with sides of X/2, the standing QED photons created have wavelength X.
In the double prism, the gap d is a QED cavity having a resonant wavelength 2d that corresponds to a barrier having Planck energy EB = hc/2d, where h is Planck’s constant and c the speed of light. Now, a single incident photon having wavelength W has Planck energy E = hc/W. Since E < EB , the incident photon cannot breach the barrier. Over time, however, absorbed EM energy from a number of incident photons accumulates in the QED cavity until saturation breaches the barrier. Saturation requires the number N of incident photons, N = EB /E = W/2d > 1.
QED tunneling by the creation of propagating photons supports Winful’s interpretation of the Hartman effect by the saturation time of stored incident photon energy in the barrier. Unlike evanescent photons that cannot propagate across the gap, the QED created photons not only propagate across the gap, but travel beyond into the outside world. Assuming the Planck energy E of a single incident photon is localized in the QED cavity in time 2d/c, the time t* to create a QED photon from N incident photons is, t* = N*2d/c = W/c. Consistent with the Hartman effect, the time t* therefore tends to a constant independent of the gap d while depending only on the wavelength W of the incident photons, i.e., for W < 2d, there is no QED cavity effect with the incident photons localizing in the gap in their own time, t* = W/c.
The QED conversion of EM energy from non-propagating evanescent waves to propagating photons that can interact with the outside world need not be limited to the Hartman effect. In this regard, BB thermal radiation is the source of EM energy in near-field radiative heat transfer across gaps d. BB radiation having wavelengths W >> d is thought to transmit radiation across nanoscale gaps by evanescent waves. Unlike incident photons from an external laser in the double prism, atoms in the surfaces of nanoscale gaps are physically part of the QED cavity, and therefore the surface atoms naturally supply the EM energy needed by QED to create standing wave photons that transfer radiation across the gap. Indeed, QED tunneling in micron gaps may provide a more practical solution in radiative heat transfer than the nanoscale gaps required for evanescent tunneling. See PPT presentation at NANORAD 2012 “Invalidity of Near Field Heat Transfer,” http://www.nanoqed.org, 2012.
2. QED by converting the stored EM energy of evanescent waves to QED photons that can propagate across the barrier to the outside world supports Winful’s argument that the Hartman effect has nothing to do with superluminality.
3. In radiative heat transfer, QED tunneling in micron gaps may offer a practical advantage over evanescent tunneling in nanoscale gaps.
T. E. Hartman "Tunneling of a wave packet," vol. 33, J. Appl. Phys., pp. 3427 (1962).
H. Winful "Tunneling time, the Hartman effect, and superluminality:
H. Winful, “Origin of the Hartman Effect,” p. 47 of
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New Perspectives on the Pitheciines
If the callitrichines were the first major group of platyrrhines to benefit scientifically from the explosion of interest in platyrrhine biology in the last two decades, the sakis and uakaris are the surprise discovery. They are the evolutionary secret of the New World monkey radiation, hidden until now by the lack of a sound framework for platyrrhine systematics, the absence of any glimmerings of a fossil record and sheer ignorance of their behavior and ecology. Much the same situation existed for callitrichines. For nearly a hundred years, scientists have debated one way or the other - Are the callithrichines primitive or are they derived? No such uncertainties were ever associated with “pitheciines”. Classifications dating to J.E. Gray and St. George Mivart in the middle 1800s show that taxono- mists even then treated the three modern genera, Pithecia, Chiropotes, and Cacajao as a divergent, natural group. In modern terms, this implies they are monophyletic, related more closely to one another than any are to living non-pitheciine platyrrhines. Until recently, this legacy was the upshot of“pitheciine” biology: sakis and uakaris are behaviorally enigmatic and structurally bizarre, but they are an evolutionary cohesive group.
KeywordsMiddle Miocene Seed Predator Terra Firme Loud Call Titi Monkey
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- Ayres, J.M. 1981. Observaçōes sobre a ecologia e o comportamento dos cuxiõs (Chiropotes albinasus e Chiropo-tes satanas, Cebidae: Primates). Unpublished Master of Science Thesis, Instituto Nacional de Pesquisas da Amazõnia e Fundaçâāo Universidade do Amazonas, Manaus, Brazil.Google Scholar
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An Experimental Study of Free Convection in Horizontal Tubes with Different end Temperatures
Several kinds of cryogenic apparatuses employ horizontal vent tubes. This paper examines the gravity-induced flow in long horizontal tubes having ends maintained at different temperatures, i.e. one end cooled and one at room temperature. Two cases are tested: (1) when the cold end is open to the cryogenic fluid reservoir and (2) when both ends are closed. The temperature distribution along the tube wall is measured and the flow pattern visualized. The measurements demonstrate that a considerable amount of heat is transported by free convection from the end at room temperature to the cold end. The results are compared with analytical expressions.
KeywordsHeat Input Rayleigh Number Heat Mass Transfer Free Convection Bottom Wall
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- 1.W. D. Lee, Continuous transfer of liquid helium to a rotating dewar, B. S. and S. M. thesis, Massachusetts Institute of Technology (1970).Google Scholar
- 2.A. Bejan, Improved thermal design of the cryogenic cooling system for a superconducting synchronous generator, Ph. D. thesis, Massachusetts Institute of Technology (1974).Google Scholar | <urn:uuid:a4ca9e5a-9e5b-483a-b4eb-2c5d47612e15> | 2.90625 | 255 | Academic Writing | Science & Tech. | 40.692769 | 95,523,919 |
Researchers from the RSPB and BirdLife Middle East have tracked a group of northern bald ibis on their 1,900-mile (3,100-kilometre) journey from breeding grounds in Palmyra, Syria to the highlands of Ethiopia.
The three birds carrying satellite tags, named Zenobia, after Palmyra’s third century warrior queen, Sultan and Salam, are feeding and sheltering at more than 2,600 metres in Ethiopia’s central highlands, about 50 miles (80km) from the country’s capital, Addis Ababa.
Ethiopian conservationists found the trio and a fourth bird last week. In total, 13 bald ibis left Palmyra in July and scientists are hoping that the other birds will join them or are close by. Their task now is to protect the birds while they migrate and so increase their numbers.
Chris Bowden, bald ibis specialist at the RSPB, said: “Knowing where these birds go and how they get there is a major breakthrough. They have been in Ethiopia since August and are likely to stay there until they return to Syria.
“We thought the birds would go to Yemen, Eritrea or Somalia and were surprised at the length of their journey and the speed with which they covered the distance.
“They have chosen their site well because Ethiopia is famous for its protection of wildlife and their last port of call was Yemen where the government is also supportive. This has answered a big question mark that remained for this species, and one that we feared we might never resolve.”
Northern bald ibis were rediscovered in Syria only four years ago and the group is one of just two wild populations of the species in the world. The other is in Morocco, mostly in the Souss-Massa National Park, south of Agadir.
Despite breeding well in Syria where the birds are protected by Bedouin nomads and Syrian government rangers, the colony’s numbers have not increased. Scientists fear that hunting, overgrazing or the heavy use of pesticides including DDT somewhere on the birds’ migration route is keeping numbers low.
The tracked birds reached Ethiopia via Jordan, Saudi Arabia and Yemen, where they spent three weeks. Six birds were seen in Yemen before at least four crossed the Red Sea to Ethiopia.
Northern bald ibis were last seen in Ethiopia in 1977 but their current site is remote and the terrain difficult, which may explain why they have not been seen since.
Scientists will now learn what local people know of past visits by bald ibis to Ethiopia. Measures to protect the birds elsewhere could include replacing harmful pesticides or making hunters aware of how rare the northern bald ibis is.
Mengistu Wondafrash, Team Leader at the Ethiopian Wildlife and Natural History Society, was amongst those to find the ibis last week. He said: “As we searched, we were not getting any signals from the tranmitters so finding the birds in such a remote area was a wonderful surprise. They were perched on a rocky outcrop close to a large pond and fairly close to a village.
“The area is used for livestock grazing but there were still many other species of bird using the pond and the area around it. We are very hopeful that the other bald ibis from Syria are nearby and we will be making a second visit to the area next month to try to find them. In Ethiopia, we will be doing all we can to implement conservation measures to help increase the numbers of this rare but special bird.”
The Yemeni Environment Minister, Abdul-Rahman F. al-Eryani, also saw the birds while they were in Yemen. He said: “I was very excited to find that the birds could once more be seen in Yemen. We recognise the importance to our country of their migration and we will be waiting for them to return on their way back to Syria. We will do our very best to see them safely on their way.”
Ibrahim Khader, Head of BirdLife Middle East, said: “We are optimistic that protection of the ibis in Ethiopia and Yemen will be good but the birds must still survive a perilous journey to get there each year. It is our job to make that journey safer. If we can do that, this population will have a much better chance of survival.”
Cath Harris | 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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Juni Kriswantojuni/AFP/Getty Images
A massive upwelling of hot rock is rising under part of New England, including Western Massachusetts, raising the possibility of a volcanic eruption, but don’t jump in the car just yet. If it does happen, it will be tens of millions of years from now, new research suggests.
The study, by researchers from Rutgers University and Yale University, was published recently online in the journal Geology.
“The upwelling we detected is like a hot air balloon, and we infer that something is rising up through the deeper part of our planet under New England,” lead author Vadim Levin, professor in the Department of Earth and Planetary Sciences at Rutgers University-New Brunswick, said recently in a statement.
Levin said it was a “distant relative” of what is happening at Yellowstone National Park. “Something relatively small — no more than a couple hundred miles across — is happening.”
Yellowstone is the site of a supervolcano that has been sleeping for about 640,000 years but could wreak devastation if it erupted.
The bubble of rock Levin studied is largely beneath central Vermont, Western New Hampshire, and Western Massachusetts, he said.
“It will likely take millions of years for the upwelling to get where it’s going,” he added. “The next step is to try to understand how exactly it’s happening.”
Levin said the Atlantic edge of North America has not experienced intense geological activity for nearly 200 million years.
In the region now, “slow loss of heat within the Earth and erosion by wind and water on the surface are the primary change agents. So we did not expect to find abrupt changes in physical properties beneath this region, and the likely explanation points to a much more dynamic regime underneath this old, geologically quiet area.”
Levin said in a telephone interview that previous researchers had found warm areas under the surface of the earth on the East Coast.
“The novelty in our research is an ability to provide an argument for its motion,” he said. “It’s not just hot. We can see that it’s doing something.” He said he and his fellow researchers, his colleague Maureen Long at Yale and three Rutgers and Yale undergraduates, were able to “confirm that the rock was flowing ... and that the motion was vertical.”
A backlog in emergency departments slows treatment for mentally ill patients and creates stress for doctors and nurses, who are generally not well-trained to manage patients who might be psychotic, violent, or suicidal.Continue reading »
A lawyer for Emanuel Lopes said he has “been unable to speak with him in any coherent fashion” about the case, but the judge decided Lopes was aware of what was happening.Continue reading »
The video shows Theresa Lund, executive director of the Harvard Humanitarian Initiative, asking a neighbor if she lived in the “affordable apartments.”Continue reading »
A Lowell man is now facing stalking charges following a monthlong investigation by Lowell and Winchester police.Continue reading »
Liberals lawmakers had wanted the budget to prohibit police from performing some federal immigration duties.Continue reading »
The mayor is taking a two-day trip to Republican-leaning districts in Ohio and Indiana where Democrats are vying for congressional seats.Continue reading »
Massachusetts leaders think it’s time to apply the state’s Yankee ingenuity — its potent mix of brainpower and technology prowess — to solving the problems of aging.Continue reading »
Just be courteous and think about the people who might use that bike after you.Continue reading »
The State Police say they have brought in a familiar face to consult and bring change to the department: former state public safety secretary Kathleen O’Toole.Continue reading » | <urn:uuid:2e7fe0e3-2a9d-456a-92e5-7b9220002f0a> | 3.65625 | 809 | News Article | Science & Tech. | 39.38382 | 95,523,939 |
You’re no doubt familiar with the projected impacts of global warming on Earth’s environments. It’s important to also know that there are also significant changes in store for marine ecosystems and their inhabitants. Consider the following:
- Increased surface temperatures are liable to cause ocean acidification, which will impact dramatically on marine life. The sea absorbs carbon dioxide from the atmosphere, and this bonds with seawater to generate carbonic acid. Increased atmospheric carbon dioxide will increase and accelerate the chemical outcomes of this process, changing the chemical nature of the underwater environment. Effects include certain ions that many sea creatures require for building shells and skeletons becoming unavailable.
- Higher water temperatures cause corals to expel the algae that give them their colour and help create their protective outer skeletons. The departure of the algae results in what is known as coral bleaching. This leaves the colonies of animals (called polyps) that inhabit them vulnerable, and the coral may then die.
- Rising temperatures, both on the surface and in the water, can affect the life cycles and behaviours of marine animals, many of which rely on temperature as a cue for reproduction. There are also more complex factors in the mix – for example, the offspring sex ratios of some species (such as marine turtles) are temperature dependent. The outcomes of changed temperatures for marine populations are difficult to predict. | <urn:uuid:c1ecc5e2-978b-41b6-a8a3-9ba66da3369c> | 4.125 | 274 | Knowledge Article | Science & Tech. | 21.123442 | 95,523,975 |
Assertions and the Verification Landscape
This chapter presents an overview of assertions and their use throughout the product development lifecycle, including hardware verification, debug and monitoring. Assertions use in the areas of simulation, emulation and formal verification are overviewed. Assertion checkers and checker generators, two central themes in this book, are also presented. An introduction to temporal logic is also performed, given the strong foundations of assertion languages in this area. With the origins of assertion residing in the software side, it is only fitting to begin the chapter with a survey of assertions in software.
KeywordsModel Check Clock Cycle Linear Temporal Logic Execution Trace Liveness Property
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Researchers at the Institute of Biotechnology at the Helsinki University and the Universitat Autonoma de Barcelona (UAB) have developed the first three-dimensional simulation of the evolution of morphology by integrating the mechanisms of genetic regulation that take place during embryo development. The study, published in Nature, highlights the real complexity of the genetic interactions that lead to adult organisms’ phenotypes (physical forms), helps to explain how natural selection influences body form and leads towards much more realistic virtual experiments on evolution.
“Right now we have a lot of information on what changes in what genes cause what changes in form. But all this is merely descriptive. The issue is to understand the biological logic that determines which changes in form come from which changes in genes and how this can change the body”, explains Isaac Salazar, a researcher at the University of Helsinki and in the Department of Genetics and Microbiology of the UAB, and lead author of the article. In nature this is determined by embryo development, during the life of each organism, and by evolution through natural selection, for each population and species.
But in the field of evolution of organisms it is practically impossible to set up experiments, given the long timescale these phenomena operate on. This means that there are still open debates, with hypotheses that are hard to prove experimentally. This difficulty is compensated for by the use of theoretical models to integrate in detail the existing experimental data, thus creating a virtual simulation of evolution.
The researchers used a theoretical model based on experiments on embryo development, on a previous study by the same authors, also published in Nature (Salazar-Ciudad and Jernvall, 2010), and on three different mathematical models of virtual evolution by natural selection of form. Evolution takes place virtually on the computer in populations of individuals in which each individual can mutate its genes, just as this works in nature. Through the development model, these produce new morphologies and natural selection decides which ones pass on to the next generation. By repeating the process in each generation, we can see evolution in action on the computer.
This simulation enables a comparison of the different hypotheses in the field of evolution regarding which aspects of morphology evolve most easily. The first vision is that all metric aspects of form contribute to adaptation and that, consequently, all are fine-tuned by evolution over time. The second vision is that some aspects of form have greater adaptive value and that the remainder evolve collaterally from changes in these. The third is that no aspect of form is intrinsically more important, but what is important adaptively is a complex measurement of the form’s roughness.
“What we have found is that the first hypothesis is not possible and that the second is possible in some cases. Even if ecology favoured this type of selection (the first vision), embryo development and the relationship between genetic and morphological variation imposed by this is too complex for every aspect of morphology to have been fine-tuned. In one way, what we are seeing is that natural selection is constantly modelling body forms, but these are still a long way from perfection in many ways”, points out Salazar.
The study was led by Isaac Salazar-Ciudad and involved the UAB trainee researcher Miquel Marín Riera. Part of it was completed by the “evo-devo” community (embryonic evolution and development) at the Institute of Biotechnology of the University of Helsinki and another part by the Research Group on Genomics, Bioinformatics and Evolution of the UAB.
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