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On 15 May IASS Director Mark Lawrence will present the latest research on black carbon and its effects on health, the climate, and development in a short talk at the preparatory meeting for the UN Climate Conference in Bonn.
Particulate matter puts human health in danger: Everybody who inhales it is at risk of developing cardiovascular and respiratory problems. Soot, which is mainly made up of black carbon, is emitted from diesel motors, industrial chimneys, and heating stoves, thereby adding to air pollution.
The fine carbon particles in the air threaten not only human health but also the climate, since black carbon contributes to global warming. When soot particles settle on snow and ice, the Earth’s capacity for reflecting sunlight back into space is reduced. As a result, ice melts more quickly and the temperature rises.
Conversely, by tackling black carbon, we can kill two birds with one stone and protect both health and the climate. This is why the negative effects of black carbon are increasingly in the spotlight. How can policymakers and researchers make progress towards reducing it?
At the preparatory meeting for the UN Climate Conference in Bonn, IASS Director and climate scientist Mark Lawrence will give a short talk on the latest research on black carbon and discuss its effects on health, the climate, and development.
Watch his talk live on YouTube:
"Climate and development benefits of black carbon mitigation"
Date and time: 15.05.2017 at 15:00 (CEST)
Live stream from the UNFCCC Climate Change Studio
For more detailed background information on black carbon emissions and policy recommendations for reducing them, see the Policy Brief prepared by the IASS together with Environmental Action Germany (DUH):
“Black Carbon in Europe – Targeting an Air Pollutant and Climate Forcer” by Erika von Schneidemesser (IASS), Kathleen A. Mar (IASS), and Dorothee Saar (DUH)
Find out more about the links between greenhouse gases, climate change, and air quality in our dossier "Air Pollution and Climate Change"
For further information, please contact
Eva Söderman and Anja Krieger
Press & Communications
Institute for Advanced Sustainability Studies e.V. (IASS)
Berliner Straße 130, 14467 Potsdam
Tel. +49 (0)331 288 22-340/341
Fax +49 (0)331 288 22-310
E-Mail firstname.lastname@example.org / email@example.com
Funded by the ministries of research of the Federal Republic of Germany and the State of Brandenburg, the Institute for Advanced Sustainability Studies (IASS) aims to identify and promote development pathways for a global transformation towards a sustainable society. The IASS employs a transdisciplinary approach that encourages dialogue to understand sustainability issues and generate potential solutions in cooperation with partners from academia, civil society, policymaking, and the business sector. A strong network of national and international partners supports the work of the institute. Its central research topics include the energy transition, emerging technologies, climate change, air quality, systemic risks, governance and participation, and cultures of transformation.
Eva Söderman | idw - Informationsdienst Wissenschaft
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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20.07.2018 | Materials Sciences | <urn:uuid:0c0a589a-999d-43c6-9677-123b0ffedc28> | 3.078125 | 1,291 | News (Org.) | Science & Tech. | 35.70121 | 95,629,730 |
Birmingham Live Unlike 2017, bright moonlight won't get in the way of this year's display. There is a new moon on Saturday, August 11, meaning dark skies that night and on the next few nights. There will be only the faintest sliver of a crescent on August 12 and 13 ...
ISRAEL21c Ramon Crater Nature Reserve, considered the best place in Israel to observe the stars and planets, was declared an International Dark Sky Park in September 2017, the first ever to receive that designation in the Middle East. “Our celebrations will ...
Space.com The 2017 Perseid meteor shower — which peaks Aug. 12 — will be sandwiched between a lunar eclipse and the much-heralded 2017 total solar eclipse, marking a month of excitement in the night (and daytime) sky. The Perseid meteor shower is one of the... -
National Geographic This weekend, people around the world will be able to see pieces of a comet streaking across the sky, as the annual Perseid meteor shower reaches its peak. Considered the “old faithful” of sky shows, the Perseids put on a dazzling display every August ... --
National Geographic Annual meteor showers are nothing to fear: The streaks of light that make meteors so fun to watch are created as the debris burns up in our atmosphere. Around 21 meteor showers occur every year, and the majority of those can be seen from August to... -
NBC 10 Philadelphia The Geminid meteor shower, which returns every December, was widely regarded as the most impressive of this year, according to a NASA news release. "With August's Perseids obscured by bright moonlight, the Geminids will be the best shower this year,"... ---
USA TODAY At best, a typical Perseid meteor shower produces 80 to a few hundred meteors per hour. The best Perseid performance we know of occurred in 1993, when the peak rate topped 300 meteors per hour, Cooke said. Last year an outburst of over 200 meteors... ---
New York Times All year long as Earth revolves around the sun, it passes through streams of cosmic debris. The resulting meteor showers can light up night skies from dusk to dawn, and if you're lucky you might be able to catch one. If you spot a meteor shower, what ... ---
Tags : meteor shower august 2017, meteor shower august 2017 News | <urn:uuid:3450a136-b6b6-4204-ae56-41502c4f628a> | 2.5625 | 490 | Content Listing | Science & Tech. | 69.841571 | 95,629,735 |
A repository & source of cutting edge news about emerging terahertz technology, it's commercialization & innovations in THz devices, quality & process control, medical diagnostics, security, astronomy, communications, applications in graphene, metamaterials, CMOS, compressive sensing, 3d printing, and the Internet of Nanothings. NOTHING POSTED IS INVESTMENT ADVICE! REPOSTED COPYRIGHT IS FOR EDUCATIONAL USE.
Friday, January 8, 2016
Abstract-Absorption-induced transparency metamaterials in the terahertz regime
Contrary to what might be expected, when an organic dye is sputtered onto an opaque holey metal film, transmission bands can be observed at the absorption energies of the molecules. This phenomenon, known as absorption-induced transparency, is aided by a strong modification of the propagation properties of light inside the holes when filled by the molecules. Despite having been initially observed in metallic structures in the optical regime, new routes for investigation and applications at different spectral regimes can be devised. Here, to illustrate the potential use of absorption-induced transparency at terahertz, a method for molecular detection is presented and supported by a theoretical analysis. | <urn:uuid:c181c0a3-ff2a-4d5d-9803-0686d46d7282> | 2.5625 | 249 | News (Org.) | Science & Tech. | -3.486316 | 95,629,742 |
Earthquakes have several terms associated with them.india Updated: Mar 13, 2003 15:10 IST
The focus is the point within the Earth's crust from where seismic waves originate. The focus is also called the hypocentre and the shortest distance between the focus and the Earth's surface is called the focal distance.
The epicentre is the point on the surface of the earth vertically above the place of origin of an earthquake. It is this point that is usually referred to in news reports as the point of origin of an earthquake.
Magnitude is the amount of shaking of the ground when an earthquake affects an area. It measures the size of an earthquake in terms.
A seismograph is an instrument that measures the magnitude of an earthquake. Seismographs record the vibrations caused by the earthquake. This is recorded in a zigzag manner that shows the varying amplitude of ground oscillations beneath the seismograph. Some highly sensitive seismographs can detect strong earthquakes from sources anywhere in the world.
The time, locations, and magnitude of an earthquake can be determined from the data recorded by seismograph stations.
Inside a seismograph are levers that scratch marks on the surface of smoked paper fixed to a constantly moving drum. When the marks become irregular, it indicates the occurrence of an earthquake.
Magnitude is measured on the basis of ground motion recorded by a seismograph, which then gives a number based on the severity of the quake.
Intensity also measures the earthquake, only in terms of the effects of an earthquake at a particular site based on the observations of the affected areas, essentially measuring the effects on humans, other living beings and built structures. It is measured using a descriptive scale called Modified Mercalli Scale.
The Mercalli Scale measures the intensity of an earthquake. First developed by an Italian geologist, Guiseppe Mercalli, in 1095, the scale was modified in 1931. It is now referred to as Modified Mercalli Scale. The intensity of a quake may range from I to XII [Measure of Intensity is always written in Roman numerals]
A fault is a fracture in the rock layers within the surface of the Earth. According to type, faults are classified as strike, normal and reverse.
An earthquake generates elastic waves that travel from the source to the surface of the Earth. Seismologists are concerned with p, s and surface waves. A p wave is a primary wave that travels away from the focus and consists of a series of compressions and dilations. An s wave is the secondary wave and travels more slowly than the s wave. It consists of elastic vibrations transverse to the direction of travel. The longer the distance of a distance of a place from the focus, the greater is the arrival time between the p and s waves. Surface waves, which consist of Rayleigh Waves and Love Waves, and are even slower and follow the surface of the Earth.
The outer layer of Earth, it is about 10 to 65 kilometres thick. The crust is brittle and broken into various pieces. A lot of the earthquakes originate in this layer.
An earthquake is usually a series of quakes. While the largest vibration is termed the earthquake, smaller shocks after the quake are called aftershocks. Similarly, there may be foreshocks, which are vibrations of lesser magnitude before the quake. Aftershocks can continue to happen even hours or days after the main quake. They have occasionally been known to happen even after years or months.
The innermost part of the earth, divided into two layers. The outer core extends from 2500 to 3500 miles below the earth's surface and is liquid metal. The inner core is the central 500 miles and is solid metal.
The angle that a planar geologic surface (for example, a fault) is inclined to the horizontal surface of the Earth.
A fault is a fracture in the Earth's surface, the rocks on the either side of which have moved with respect to each other. Faults can be of strike-slip or dip-slip.
Strike-slip faults are vertical fractures where the blocks have mostly moved horizontally. Dip-slip faults are inclined fractures where the blocks have mostly shifted vertically. If the rock mass above an inclined fault moves down, the fault is termed normal, whereas if the rock above the fault moves up, the fault is termed reverse (or thrust).
The flat surface along which there is slip during an earthquake.
The outer solid layer of the earth. The lithosphere includes the crust and the mantle. The lithosphere is about 100 km thick, although its thickness is age dependent (older lithosphere is thicker).
A section of a fault that has produced earthquakes in the past but is now quiet.
Maps that plot the location of earthquakes, big and small.
A very large wave, caused by the occurance of an earthquake below the surface of the ocean bed. Capable of reaching great heights and lengths, it can wreak extensive damage to coastal areas. | <urn:uuid:df27f837-cb2b-4cf3-8b07-173837e0a42b> | 4.21875 | 1,018 | Knowledge Article | Science & Tech. | 49.743968 | 95,629,753 |
The image is a composite made from 18 separate images taken using Hubble’s Advanced Camera for Surveys (ACS), and it shows the Cas A remnant as a broken ring of bright filamentary and clumpy stellar ejecta. These huge swirls of debris glow with the heat generated by the passage of a shockwave from the supernova blast. The various colours of the gaseous shards indicate differences in chemical composition. Bright green filaments are rich in oxygen, red and purple are sulphur, and blue are composed mostly of hydrogen and nitrogen.
The colourful aftermath of a violent stellar death A new image taken with the NASA/ESA Hubble Space Telescope provides a detailed look at the tattered remains of a supernova explosion known as Cassiopeia A (Cas A). It is the youngest known remnant from a supernova explosion in the Milky Way. The new Hubble image shows the complex and intricate structure of the star’s shattered fragments.
A supernova such as the one that resulted in Cas A is the explosive demise of a massive star that collapses under the weight of its own gravity. The collapsed star then blows its outer layers into space in an explosion that can briefly outshine its entire parent galaxy. Cas A is relatively young, estimated to be only about 340 years old. Hubble has observed it on several occasions to look for changes in the rapidly expanding filaments.
In the latest observing campaign, two sets of images were taken, separated by nine months. Even in that short time, Hubble’s razor-sharp images can observe the expansion of the remnant. Comparison of the two image sets shows that a faint stream of debris seen along the upper left side of the remnant is moving with high speed - up to 50 million kilometres per hour (fast enough to travel from Earth to the Moon in 30 seconds!).
Cas A is located ten thousand light-years away from Earth in the constellation of Cassiopeia. Supernova explosions are the main source of elements more complex than oxygen, which are forged in the extreme conditions produced in these events. The analysis of such a nearby, relatively young and fresh example is extremely helpful in understanding the evolution of the Universe.
Lars Christensen | alfa
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
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16.07.2018 | Earth Sciences | <urn:uuid:5998de58-efc9-45bc-9fe7-d6fd6bc4f3d9> | 3.453125 | 1,090 | Content Listing | Science & Tech. | 40.993929 | 95,629,754 |
Novel services for tropical forest monitoring with satellite
A consortium led by VTT Technical Research Centre of Finland is developing methods for monitoring tropical forests using satellite data in a project funded by the 7th Framework Programme of the European Commission. The objective of the ReCover project is to develop beyond the state-of-the-art service capabilities currently supporting the United Nations REDD programme which is fighting deforestation and forest degradation in the tropical region.
Although REDD will probably not be officially accepted at the climate conference in Cancun, several REDD-related activities are already under way in the tropical region.
The methods to be developed in the ReCover project will combine lower resolution but full area coverage optical and radar satellite imagery with a sample of very high resolution satellite data and ground data. The very high resolution imagery, with an accuracy reaching to 0.5 metres, particularly supports monitoring of degradation and increases the general reliability of the results.
The study areas of the ReCover project are in Mexico, Guyana, Brazil, Central Africa and the Fiji Islands. For each of the study sites a local user is closely involved in the method development. The consortium has nine research and industrial partners, of which three are outside Europe.
The leading idea behind REDD is that countries that are willing to reduce emissions from deforestation will be financially compensated for doing so. The REDD process requires a monitoring system in which satellite imagery will have a key role. Monitoring of forest degradation introduces particular challenges for the monitoring system.
The ReCover project started in November 2010 and will last three years. Its total budget is about EUR 3.5 million.
Forest biomass map of very high resolution satellite data (photo: VTT)
Tropical forests, map
Research Professor Tuomas Häme
firstname.lastname@example.org, tel. +358 20 722 6282
VTT Technical Research Centre of Finland is a leading multitechnological applied research organization in Northern Europe. VTT creates new technology and science-based innovations in co-operation with domestic and foreign partners. VTT’s turnover is EUR 280 million and its personnel totals 2,900. | <urn:uuid:d2a039f6-994c-45d9-9c23-313ea821336d> | 2.5625 | 440 | News (Org.) | Science & Tech. | 26.804495 | 95,629,760 |
''The exciting thing is really for the first time, using a time series of satellite images, we can monitor Earth in a way that we haven't been able to,'' Seto said. ''It's not just about urban growth or wetlands-it could be about desertification or deforestation-but it's really just this issue of human modification of the Earth.''
In one study, published in the July online issue of the journal Global Environmental Change, Seto and her colleagues showed that inclusion in an international environmental agreement did not significantly improve the health of a coastal mangrove habitat in a wetland preserve in Vietnam. In the second study, published May 15 in the Journal of Climate, the researchers found that rapid urban growth has caused drier winters in the Pearl River Delta of China.
Both findings are based on an analysis of satellite images of Vietnam and China, which NASA has been collecting through its Land Remote-Sensing Satellite (Landsat) Program for more than 30 years.
Urban growth in China
The Journal of Climate study focused on the People's Republic of China, where special economic zones have been established to attract foreign investment and generate international trade. One zone, Shenzhen, was created in 1980 in the Pearl River Delta just north of Hong Kong. Seto, a Hong Kong native, witnessed the impact of this designation during successive visits with relatives in mainland China.
In a previous paper, Seto and her colleagues analyzed satellite imagery and found that urban areas in the Pearl River Delta increased more than 300 percent from 1988 to 1996. In the Journal of Climate study, the researchers compared this rapid urban growth with monthly temperature and precipitation data from 16 meteorological stations. Their analysis revealed a direct correlation between the rapid growth of cities and a decrease in rainfall during the winter dry seasons from 1988 to 1996.
''We found that as the cities get bigger, there is a negative impact on precipitation patterns, such that in the winter season there is a reduction in rainfall as an effect of urbanization,'' Seto explained. ''Primarily it is caused by the conversion of vegetated land to asphalt, roads and buildings. As a result, the soils have significantly less ability to absorb water, so in the winter months there is less moisture in the atmosphere and therefore a reduction in precipitation. We don't see the same impact in summer months, in part because the effect of the Asian monsoon masks the effect of urbanization.''
''When cities are still relatively small, we don't see this pattern emerging,'' she added. ''It happens when cities get very large. But that's the part that I think is alarming, because we see large-scale city development all over China and throughout the developing world.''
Coastal changes in Vietnam
In the Global Environmental Change study, the researchers focused on Vietnam, a signatory of the Convention on Wetlands of International Importance Especially as Waterfowl Habitat, drafted in Ramsar, Iran, in 1971. The goal of the treaty was to protect wetlands by promoting sustainable use of resources found there. To date, more than 150 countries, including the United States, have signed the convention. The Florida Everglades and portions of the Ganges River in India and the Red River Delta in northern Vietnam are included on the convention's list of wetlands of international importance.
The growth of aquaculture in recent years has threatened coastal mangrove forest habitats in the Red River Delta. In response, the Vietnamese government has established protected areas, such as the Xuan Thuy Natural Wetland Reserve, which was designated a Ramsar site in 1988.
For the study, Seto and her colleagues concentrated on Xuan Thuy and a nearby reserve that is not included in the Ramsar treaty. The researchers analyzed a series of Landsat images taken between 1975 and 2002. Analysis revealed that both reserves experienced increased fragmentation of mangrove forest habitat with increased aquaculture. Contrary to expectations, the scientists found that aquaculture developed at a faster rate at the Xuan Thuy treaty site than at its non-Ramsar neighbor.
These findings mirrored statements by local residents in 2001, when Seto and her co-workers interviewed one-third of the households living and farming within the boundaries of both reserves. The researchers were told that aquaculture had been ongoing in the region since the early 1980s.
These results showed that satellite technology is a cost-effective means of assessing wetland health, Seto said, noting that the cost of acquiring the satellite images and conducting the interviews in the field totaled less than $5,000.
This technique could be used to verify compliance with other environmental agreements, added Ron Mitchell, professor of public policy at the University of Oregon and an expert on multi-national environmental treaties. ''Too often in the past policymakers have been at a loss as to how to evaluate progress,'' he said. ''Remote sensing could be used to evaluate many international environmental agreements, particularly habitat-based conventions, such as Ramsar or those dealing with deforestation, desertification and carbon sequestration projects under a climate change agreement.''
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine | <urn:uuid:ed07ce08-7cfa-4647-b8b0-8091a42f1e96> | 3.796875 | 1,653 | Content Listing | Science & Tech. | 35.786413 | 95,629,778 |
Popular Science Monthly/Volume 8/February 1876/The Nature of Fluorescence
|THE NATURE OF FLUORESCENCE|
PROFESSOR OF PHYSICS IN THE UNIVERSITY OF ERLANGEN.
THE question now arises. What becomes of the rays that have undergone absorption? Are they in fact, as they appear to be, annihilated? A series of phenomena now to be considered will give us an answer to these questions.
If water containing a little esculine, a substance contained in the bark of the horse-chestnut in solution, be placed in a flask, and the Fig. 1.—Illumination of Flourescence. rays of the sun or of the electric lamp, concentrated by a lens situated at about its focal distance from the vesel (Fig. 1), be directed upon it, the cone of light thrown by the lens into the interior of the fluid will be seen to shine with a lovely sky-blue tint. The particles of the solution of esculine in the path of the beam become spontaneously luminous, and emit a soft blue light in all directions. The cone of light appears brightest at the point where it enters into the fluid through the glass, and quickly diminishes in brilliancy as it penetrates more deeply.
There are great numbers of fluid and solid bodies which become similarly self-luminous under the influence of light. This peculiarity was first observed in a kind of spar occurring at Alston Moor, in England, which, itself of a clear green color, appears by transmitted solar light of a very beautiful indigo-violet color. From its occurrence in calcium fluoride the phenomenon has been named florescence.
In order to understand more precisely the circumstances under which fluorescence occurs, the solution of esculine must again be referred to. The light, before it reaches the lens, must be allowed to pass through just such another solution of esculine contained in a glass cell with parallel walls. The cone of light proceeding from the lens, as long as it passes through the air, does not appear to have undergone any material change, it is just as bright and just as white as before. In the interior of the fluid, however, it no longer presents a blue shimmer, but becomes scarcely perceptible.
Thus it is seen that light which has traversed a solution of esculine is no longer capable of exciting fluorescence in another solution of esculine. Those rays consequently which possess this property must be arrested by the first solution of esculine. Similar results are obtained in the case of every other fluorescent substance.
The general proposition can therefore be laid down, that a body capable of exhibiting fluorescence fluoresces by virtue of those rays which it absorbs.
In order to determine what rays in particular cause the fluorescence of esculine, the spectrum must be projected in the usual way; but, instead of its being received upon a paper screen, it must be allowed to fall upon the wall of a glass cell containing a solution of esculine, that is to say, upon the solution itself, and it must then he observed in what parts of the spectrum the blue shimmer appears. The red and all the other colors consecutively down to indigo appear to be absolutely without effect. The bluish shimmer first commences in the neighborhood of the line G (Fig. 2), and covers not only the violet part of the spectrum, but stretches far beyond the group of lines H to a distance which is about equal to the length of the spectrum visible under ordinary circumstances.
From this the conclusion must be drawn that there are rays which are still more refrangible than the violet, but which in the ordinary mode of projecting the spectrum are invisible; these are termed the ultra-violet rays. They become apparent in the esculine solution because they are capable of exciting the bluish fluorescent shimmer in it. If sunlight have been used in the above experiments, the well-known Fraunhofer's lines appear upon the bluish ground of the fluorescing spectrum, not only from G to H, but the ultra-violet part also appears filled with numerous lines, the most conspicuous of which are indicated by the several letters L to S (Fig. 2). That these lines, like the ordinary Fraunhofer's lines, belong properly to solar light, and do not depend upon any action of the fluorescing substance, is evident from the circumstance that with the electric light they are no more apparent in the ultra-violet than in the other colors, and further, because the same lines are seen in the solar spectrum, whatever may be the fluorescing substance under examination.
Quartz has the power of transmitting the ultra-violet rays far more completely than glass. If, therefore, the glass lens and prism hitherto used for projecting the spectrum be replaced by a quartz lens and prism, the ultra-violet part of the spectrum is rendered much brighter and is extended still farther than before.
The ultra-violet rays of the spectrum can, moreover, be seen, without the intervention of any fluorescing substance, through a glass, or, still better, through a quartz prism, if the bright part of the spectrum between B and H (Fig. 2) be carefully shut off. With feeble illumination its color appears indigo-blue, but with light of greater intensity it is of a bluish-gray tint (lavender). The ultra-violet rays thus ordinarily escape observation, because they produce a much feebler impression on the human eye than the less refrangible rays between B and H.
An explanation is thus afforded why the solution of esculine, apart from its absorption, is colorless when seen by transmitted light; for, since it absorbs only the feebly luminous violet and the entirely imperceptible ultra-violet rays, the mixed light that has passed through it still appears white, and is not rendered materially fainter.
If the solar spectrum be thrown in the above-mentioned manner upon the fluid, its fluorescing part everywhere exhibits the same bluish shimmer; and spectroscopic examination shows that this bluish light has always the same composition, whether it is excited by the G rays, or by the H rays, or by the ultra-violet rays, and that it is formed of a mixture of red, orange, yellow, green, and blue. It is thus seen that the different kinds of homogeneous light, as far as they are generally effective, produce compound fluorescent light of identical composition, the constituents of which, nevertheless, are collectively less refrangible than, or are at most equally refrangible with, the exciting rays.
Among other fluorescing bodies may be mentioned the solution of quinine, which is as clear as water, and has a bright-blue fluorescence; the slightly yellow petroleum, with blue fluorescence; the yellow solution of turmeric, with green; and the bright-yellow glass containing uranium, which fluoresces with beautiful bright-green fluorescence. It admits of easy demonstration that in these bodies also it is the more refrangible rays that call forth fluorescence. For, if we illuminate them with light which has passed through a red glass, no trace of fluorescence is visible. But, if the red be exchanged for a blue glass, the fluorescence becomes as strongly marked as Avith the direct solar light. A remarkable phenomenon is presented in the splendid bright-green light which is emitted by uranium glass under the action of blue illumination.
The highly-refrangible rays which possess in so high a degree the power of exciting fluorescence are contained in large proportion in the light emitted by a Geissler's tube filled with rarefied nitrogen. In order to expose fluorescing fluids to the influence of this light, the arrangement represented in Fig. 3 may be employed with advantage, A narrow tube is surrounded by a wider glass tube, into which the fluid is introduced by a side opening which can be closed if required. Another form of Geissler's tube is represented in Fig. 4, which contains
|Fig. 3.—Geissler's Fluorescence Tube.||Fig. 4.—Geissler's Tube with Uranium Glass Spheres.|
in its interior a number of hollow spheres composed of uranium glass. Where a beam of reddish violet nitrogen light traverses the tube, the uranium glass balls shine with a beautiful bright-green fluorescent light.
The electric light passing between carbon-points is rich in rays of high refrangibility, indeed the ultra-violet end of its spectrum reaches even farther than that of the solar spectrum. In the light of the magnesium-lamp the ultra-violet rays are also abundant, and both sources of light are therefore particularly well adapted to produce fluorescence, while gas and candle light are nearly inoperative on account of the small amount of the more refrangible rays they contain.
It would nevertheless be incorrect to infer from the above facts that the more refrangible rays are exclusively capable of exciting fluorescence. A red fluid which is an alcoholic solution of naphthaline red, and which in ordinary daylight fluoresces with orange-yellow tints of unusual brilliancy, will serve to demonstrate that even the less refrangible rays are capable of producing this effect. In fact, if the spectrum be projected upon the glass cell containing the fluid (Fig. 5), the yellow fluorescent light will be seen to commence at a point intermediate to C and D and therefore still in the red, and to
extend over the whole remaining spectrum as far as the ultra-violet. The strongest fluorescence by far is shown behind the line D in the greenish-yellow rays. It then again diminishes, and becomes a second time more marked between E and b; thence onward the fluorescence becomes fainter, then increases again in the violet, and gradually vanishes in the ultra-violet. In naphthaline red, therefore, there are rays of low refrangibility, namely, the green-yellow rays behind D, by which its fluorescence is most powerfully excited.
The fluorescence spectrum received upon the fluid shows, as we have already mentioned, three regions of stronger fluorescence, and the absorption spectrum of naphthaline, which, by placing a small cell filled with the solution in front of the slit, may be obtained upon a paper screen, gives a key to the cause of this phenomenon. In this spectrum Fig. 5 (1), a completely black band is visible in the green-yellow behind D, a dark band between E and b, while the violet end appears shaded. On employing a very strong solution of the naphthaline coloring material, the whole spectrum vanishes with the exception of the red end, which remains apparent to a point behind C. If now the absorption spectrum be compared with that thrown upon the fluid, the intimate relation between absorption and fluorescence that has already been pointed out in the esculine solution is corroborated in the minutest particulars. For every dark hand in the absorption spectrum corresponds to a bright band in the fluorescing spectrum. Every ray absorbed by the fluid occasions fluorescence, and the fluorescent light produced is the brighter, the more completely the ray is absorbed.
A second example of the excitation of fluorescence by rays of small refrangibility is exhibited by a solution of chlorophyll. The spectrum projected upon this green fluid fluoresces of a dark-red color, from B to a point within the ultra-violet, exhibiting at the same time bright bands which correspond with the dark bands in the absorption spectrum. Between B and C, where the greatest amount of absorption occurs, the fluorescence is also the most marked. But it is the middle red rays which here act so powerfully as excitants. It is remarkable that the red fluorescent light which the chlorophyll solution emits likewise lies, in regard to its refrangibility, between B and C. Chlorophyll solution affords a proof that all rays of the spectrum, with the exception of the extreme red in front of B, are capable of calling forth fluorescence. Their capacity for doing so depends simply on the power of absorption of the fluorescing substance. The most refrangible violet and ultra-violet rays are, however, characterized by the circumstance that they are capable of exciting all known fluorescing bodies.
Fluorescent light is only perceived so long as the fluorescent substance is illuminated by the exciting rays. As soon as the light falling on it is obstructed, the colored shimmer vanishes. It is only in the case of some fluorescing solid substances, as, for example, fluorspar and uranium glass, that, with the aid of appropriate apparatus (Becquerel's phosphoriscope), a very short continuance of the fluorescence may be observed to take place in the dark.
There are, however, a number of bodies which, after being excited to self-luminosity by a brilliant light, continue to shine for a certain time in the dark. A series of pulverulent white substances, namely, the sulphur compounds of calcium, strontium, and barium (which should be kept in hermetically-sealed glass tubes), do not exhibit the faintest light in a dark room. Moreover, if they be covered with a yellow glass and illuminated with the light of a magnesium-lamp, they remain as dark as before. But if the yellow be exchanged for the blue glass, and the magnesium-light be allowed to play upon them for a few seconds only, they emit in the dark a soft light, each powder having its own proper tint of color. This power of shining in the dark after having been exposed to the light is called phosphorescence. The property is possessed in a high degree not only by the above-named artificially-prepared substances, but by various minerals, as the diamond, fluor-spar, and a variety of fluor-spar called chlorophane.
- From "The Nature of Light," No. XIX. of the "International Scientific Series." | <urn:uuid:2fc030c0-b25d-43aa-9167-4c3fea3daacd> | 3.234375 | 2,914 | Knowledge Article | Science & Tech. | 39.613462 | 95,629,788 |
Achievement Could Improve Understanding of Superconductivity
The images above show the creation of ultracold molecules during the JILA experiments. Left -- A rainbow color scale indicates the numbers of ultracold gaseous potassium (K40) atoms in the vacuum chamber in two different fermion states. White areas have the most atoms, blue areas have the fewest.
Center --After a carefully tuned magnetic field is scanned over the chamber, 50 percent of the atoms "disappear." About half the atoms pair up into loosely bound molecules and are now bosons with different states not detected by the experimental set up.
Right--A low-energy radio wave is directed at the chamber. The molecular bonds are broken and the atoms reappear in a third fermion state (fuzzy blue area in center of image).
A team of researchers at JILA, a joint institute of the Commerce Department’s National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder, has done the physics equivalent of efficiently turning yin into yang. They changed individual potassium atoms belonging to a class of particles called fermions into molecules that are part of a fundamentally different class of particles known as bosons. Though the transformation lasts only a millisecond, the implications may be long lasting.
The work, reported in tomorrow’s edition of the journal Nature, is an important step toward creating a “super molecule,” a blend of thousands of molecules acting in unison that would provide physicists with an excellent tool for studying molecular quantum mechanics and superconductivity. Creation of a “super atom” (known as a Bose-Einstein condensate or BEC; see www.bec.nist.gov for more information) earned another research team at JILA the 2001 Nobel Prize in physics.
Fred McGehan | NIST
Computer model predicts how fracturing metallic glass releases energy at the atomic level
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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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Light causes drosophila to take longer midday nap
News Sep 16, 2016
Fruit flies' activity peaks especially in the morning and late afternoon. The insects extend their midday siesta on long summer days. Researchers from the University of Würzburg have now found out what triggers this behavior. A miniature pair of eyelets also discovered in Würzburg in the late 80s plays a crucial role in this context.
In 1989, the Würzburg biologists Alois Hofbauer and Erich Buchner reported a surprising finding in the journal Naturwissenschaften: They had identified a new pair of eyelets in drosophila unknown until then. The fruit fly was considered an important model organism for zoologists and geneticists even back then with scores of scientists showing an interest in the tiny insect. But they had all failed to detect the additional eyes—no wonder given their microscopic size: Each eyelet consists of just four photoreceptor cells.
In spite of this, the Hofbauer-Buchner eyelets seem to play a major role in the life of drosophila. A study conducted by scientists from the University of Würzburg with colleagues from the University of Michigan and the University of Bristol has come to this conclusion.
Drosophila's activity peaks in the morning and in the late afternoon and they rest during the hottest time of the day. The tiny sensory organs evidently influence when this midday siesta ends. "On long summer days, they delay the onset of the afternoon activity phase," explains Professor Charlotte Helfrich-Förster from the University of Würzburg's Biocenter.
Hardwired in the fly's brain
The scientist has studied drosophila's circadian rhythms for years. In the current study, her research team has been able to show for the first time that the Hofbauer-Buchner eyelets are wired to a clock neuron network in the flies' brain: Nerve fibres run directly from the eyelets to two groups of clock neurons. One of them is responsible for the morning activity whereas the other influences the evening activity.
"At daybreak, light falls onto the eyelets," Helfrich-Forster details. "This light input triggers the production of the two neurotransmitters histamine and acetylcholine. We suppose that acetylcholine activates the neurons relevant for morning activity. At the same time, the histamine seems to indirectly inhibit the circadian clock for the evening peak phase thereby extending the phase of inactivity." Hence, the Hofbauer-Buchner eyelets are part of a complex network that governs drosophila's sleep/activity rhythm.
Mammalian clock similar to that of flies
Another reason why the findings are interesting is because the circadian clocks of animals have changed comparably little in the course of evolution. "Mice, for example, have a neuronal clock network in their brains that shares many similarities with that of the fruit fly," Helfrich-Förster emphasises. "Therefore, drosophila allows us to get deep insights into the circadian clock of mammals and probably into that of humans, too."
Note: Material may have been edited for length and content. For further information, please contact the cited source.
Schlichting M et al. A Neural Network Underlying Circadian Entrainment and Photoperiodic Adjustment of Sleep and Activity in Drosophila. Journal of Neuroscience, Published August 31 2016. doi: 10.1523/JNEUROSCI.0992-16.2016
What Makes Good Brain Proteins Turn Bad?News
The protein FUS is implicated in two neurodegenerative diseases: amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Using a newly developed fruit fly model, researchers have zoomed in on the protein structure of FUS to gain more insight into how it causes neuronal toxicity and disease.
Researchers are One Step Closer to Developing Eye Drops to Treat Age-Related Macular DegenerationNews
Scientists at the University of Birmingham are one step closer to developing an eye drop that could revolutionise treatment for age-related macular degeneration (AMD).READ MORE
A Bad Mood May Help Your Brain With Everyday TasksNews
New research found that being in a bad mood can help some people’s executive functioning, such as their ability to focus attention, manage time and prioritize tasks.READ MORE | <urn:uuid:f4184053-f26a-42df-95c3-e10dd43e826a> | 3.328125 | 927 | News Article | Science & Tech. | 37.235697 | 95,629,823 |
Review of Chionelasmus darwini (Pilsbry, 1907) (Cirripedia : Balanomorpha) : A Comparison between the Pacific and Indian Ocean Populations Review of Chionelasmus darwini (Pilsbry, 1907) (Cirripedia : Balanomorpha) : A Comparison between the Pacific and Indian Ocean Populations
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Chionelasmus darwini (Pilsbry, 1907) was first collected at 417 to 430m depth near Kauai, Hawaiian Islands. Pilsbry (1911) subsequently recognized that it was distinct from Catophragmus s. s. and proposed the subgenus Chionelasmus to accommodate it. Nilsson-Cantell (1928) elevated Chionelasmus to full generic rank based on a complete specimen collected from 526m depth off Port Mathurin, Rodrigues Island in the western Indian Ocean, largely because the wall turned out to be composed of six rather than eight plates. These two specimens plus 11 specimens from the Hawaiian Islands and three specimens from Madagascar contained in the Benthic Invertebrate Collection of Scripps Institution of Oceanography, and one from the Kermadec Islands of the South Pacific (Foster 1981), were utilized in the present study. The morphology of the scutum and tergum and the ontogenetic development of the third and fourth whorls of basal imbricating plates in the Pacific and Indian Ocean populations are different, and therefore a new subspecies, Chionelasmus darwini cantelli, is proposed for the latter.
- Species Diversity
Species Diversity 3(1), 117-131, 1998
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Growth rate (group theory)
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In group theory, the growth rate of a group with respect to a symmetric generating set describes the size of balls in the group. Every element in the group can be written as a product of generators, and the growth rate counts the number of elements that can be written as a product of length n.
Let us consider the subset of all elements of G which can be presented by such a word of length ≤ n
More geometrically, is the set of vertices in the Cayley graph with respect to T which are within distance n of the identity.
Given two nondecreasing positive functions a and b one can say that they are equivalent () if there is a constant C such that
for example if .
Then the growth rate of the group G can be defined as the corresponding equivalence class of the function
where denotes the number of elements in the set . Although the function depends on the set of generators T its rate of growth does not (see below) and therefore the rate of growth gives an invariant of a group.
The word metric d and therefore sets depend on the generating set T. However, any two such metrics are bilipschitz equivalent in the following sense: for finite symmetric generating sets E, F, there is a positive constant C such that
As an immediate corollary of this inequality we get that the growth rate does not depend on the choice of generating set.
Polynomial and exponential growth
for some we say that G has a polynomial growth rate. The infimum of such k's is called the order of polynomial growth. According to Gromov's theorem, a group of polynomial growth is a virtually nilpotent group, i.e. it has a nilpotent subgroup of finite index. In particular, the order of polynomial growth has to be a natural number and in fact .
- A free group with a finite rank k > 1 has an exponential growth rate.
- A finite group has constant growth – polynomial growth of order 0 – and includes fundamental groups of manifolds whose universal cover is compact.
- If M is a closed negatively curved Riemannian manifold then its fundamental group has exponential growth rate. Milnor proved this using the fact that the word metric on is quasi-isometric to the universal cover of M.
- Zd has a polynomial growth rate of order d.
- The discrete Heisenberg group H3 has a polynomial growth rate of order 4. This fact is a special case of the general theorem of Bass and Guivarch that is discussed in the article on Gromov's theorem.
- The lamplighter group has an exponential growth.
- The existence of groups with intermediate growth, i.e. subexponential but not polynomial was open for many years. It was asked by Milnor in 1968 and was finally answered in the positive by Grigorchuk in 1984. There are still open questions in this area and a complete picture of which orders of growth are possible and which are not is missing.
- The triangle groups include 3 finite groups (the spherical ones, corresponding to sphere), 3 groups of quadratic growth (the Euclidean ones, corresponding to Euclidean plane), and infinitely many groups of exponential growth (the hyperbolic ones, corresponding to the hyperbolic plane).
- Milnor J. (1968). "A note on curvature and fundamental group". J. Differential Geometry. 2: 1–7. doi:10.4310/jdg/1214501132.
- Grigorchuk R. I. (1984). "Degrees of growth of finitely generated groups and the theory of invariant means". Izv. Akad. Nauk SSSR Ser. Mat. (in Russian). 48 (5): 939–985. | <urn:uuid:7a15218e-722e-455b-b04b-8d16144af13d> | 2.796875 | 836 | Knowledge Article | Science & Tech. | 59.510392 | 95,629,845 |
$12-Million Awarded to Study the Human Genome in 4-D
News Oct 20, 2015
In order to fit within the nucleus of a cell, the human genome must bend, fold and coil into an unimaginably compact shape – and still function. This is no mean feat: The human genome is about 6.5 feet long, and the average cell nucleus is only 6 to10 micrometers (one-millionth of a meter) in diameter.
How this happens and the genome's three-dimensional shape within the nucleus are unknown. Nor is it known how the shape changes over time – the fourth dimension – as a cell develops, grows and goes about its specialized functions.
“There’s a tendency to talk about the genome as a linear sequence and to forget about the fact that it’s folded,” said Dr. Jay Shendure, University of Washington associate professor of genome sciences and investigator with the Howard Hughes Medical Institute.
“To understand how the different parts of the genome talk to each other to control gene expression, we need to understand how the different elements are arranged in relation to each other in three-dimensional space.”
To puzzle out this information and its effect on cell function in health and disease, UW researchers will join peers at five other academic institutions to create the Nuclear Organization and Function Interdisciplinary Consortium.
Underwriting the consortium is the National Institutes of Health’s 4D Nucleome program. The UW was awarded $12 million over five years to conduct research in its new Center for Nuclear Organization and Function. Shendure and William Stafford Noble, a professor of genome sciences and computer science, will co-lead.
UW researchers will first develop tools to work out the three- and four-dimensional architecture of the nucleome and to create computer models that predict changes in the architecture as cells grow, divide and differentiate into different types.
The results of this work will then be tested in mouse and human cell lines and, if confirmed, be used to understand how changes in nuclear architecture affect development of normal and abnormal heart muscle.
All tools and data developed by the project will be shared with researchers in and outside of the 4D Nucleome network of researchers and with the public.
Identical Twin Study Shows Impact of a Lifetime of Exercise on FItnessNews
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Analytical Tool Predicts Disease-Causing GenesNews
Predicting genes that can cause disease due to the production of truncated or altered proteins that take on a new or different function, rather than those that lose their function, is now possible thanks to an international team of researchers that has developed a new analytical tool to effectively and efficiently predict such candidate genes.
15th International Conference and Exhibition on Metabolomics & Systems
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The process takes place in binary stars – star systems consisting of two stars orbiting around their common centre of mass. This helps to resolve a long standing mystery in stellar evolution.
The research, which is part funded by the UK’s Science and Technology Facilities Council (STFC) and carried out by scientists at Southampton University and the McMaster University in Canada, is published in the journal Nature on Thursday 15 January.
Blue stragglers are found throughout the Universe in globular clusters - collections of about 100, 000 stars, tightly bound by gravity. According to conventional theories, the massive blue stragglers found in these clusters should have died long ago because all stars in a cluster are born at the same time and should therefore be at a similar phase. These massive rogue stars, however, appear to be much younger than the other stars and are found in virtually every observed cluster.
Dr Christian Knigge from Southampton University, who led the study, comments: “The origin of blue stragglers has been a long-standing mystery. The only thing that was clear is that at least two stars must be involved in the creation of every single blue straggler, because isolated stars this massive simply should not exist in these clusters.”
Professor Alison Sills from the McMaster University explains further: “We’ve known of these stellar anomalies for 55 years now. Over time two main theories have emerged: that blue stragglers were created through collisions with other stars; or that one star in a binary system was ‘reborn’ by pulling matter off its companion.”
The researchers looked at blue stragglers in 56 globular clusters. They found that the total number of blue stragglers in a given cluster did not correlate with predicted collision rate – dispelling the theory that blue stragglers are created through collisions with other stars.
They did, however, discover a connection between the total mass contained in the core of the globular cluster and the number of blue stragglers observed within in. Since more massive cores also contain more binary stars, they were able to infer a relationship between blue stragglers and binaries in globular clusters. They also showed that this conclusion is supported by preliminary observations that directly measured the abundance of binary stars in cluster cores. All of this points to "stellar cannibalism" as the primary mechanism for blue straggler formation.
Dr Knigge says: “This is the strongest and most direct evidence to date that most blue stragglers, even those found in the cluster cores, are the offspring of two binary stars. In our future work we will want to determine whether the binary parents of blue stragglers evolve mostly in isolation, or whether dynamical encounters with other stars in the clusters are required somewhere along the line in order to explain our results.”
This discovery comes as the world celebrates the International Year of Astronomy in 2009.
Julia Short | alfa
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Authors: Solomon I. Khmelnik
Recently, there appeared a mathematical model of oceanic whirlpools , which is almost identical to the models built for space black holes. The similarity between the whirlpools and black holes is found in the fact that an object that happened to be near these objects becomes involved in them and never returns. Such a distant analogy stresses (in our opinion) the fact that this mathematical model is very far from completion. In the presented paper the author attempts to build such a model. This model, as well as above mentioned one, has the same base – the relativity theory. However, the proposed model is more downlanded (or, if you want, water-landed), because in it we use the equations of hydrodynamics and the consequences of the theory of relativity, which are relevant only in the case of low Earth's gravity. Another question is also of interest – about the source of energy which enables the whirlpool to be spinning for a long time when surrounded by still waters. This issue becomes even more important due to the fact that the whirlpools (and not the Moon) are energy sources for the tide . In a source of energy whirlpools not analyzed. Below we show that this source is the Earth's gravitational field.
Comments: 15 Pages.
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Epoch MJD 55590.99 Equinox J2000
|Right ascension||19h 52m 46.61s|
|Declination||72° 40′ 00.61″|
|Apparent magnitude (J (2MASS filter system))||±0.04515.086|
|Apparent magnitude (H (2MASS filter system))||±0.07714.728|
|Apparent magnitude (KS (2MASS filter system))||±0.07814.650|
|Proper motion (μ)|| RA: ±69−220 mas/yr |
Dec.: ±72−347 mas/yr
|Distance||~ 44.4 ly |
(~ 13.6 pc)
WISEPA J195246.66+724000.8 (designation abbreviated to WISE 1952+7240, or WISE J1952+7240) is a brown dwarf of spectral class T4, located in constellation Draco at approximately 44 light-years from Earth.
WISE 1952+7240 was discovered in 2011 by J. Davy Kirkpatrick et al. from data, collected by Wide-field Infrared Survey Explorer (WISE) Earth-orbiting satellite — NASA infrared-wavelength 40 cm (16 in) space telescope, which mission lasted from December 2009 to February 2011. In 2011 Kirkpatrick et al. published a paper in The Astrophysical Journal Supplement, where they presented discovery of 98 new found by WISE brown dwarf systems with components of spectral types M, L, T and Y, among which also was WISE 1952+7240.[note 1]
Trigonometric parallax of WISE 1952+7240 is not yet measured. Therefore, there are only distance estimates of this object, obtained by indirect — spectrofotometric — means (see table).
WISE 1952+7240 distance estimates
|Source||Parallax, mas||Distance, pc||Distance, ly||Ref.|
|Kirkpatrick et al. (2011)||~13.6||~44.4|||
Non-trigonometric distance estimates are marked in italic.
- This 98 brown dwarf systems are only among first, not all brown dwarf systems, discovered from data, collected by WISE: six discoveries was published earlier (however, also listed in Kirkpatrick et al. (2011)) in Mainzer et al. (2011) and Burgasser et al. (2011), and the other discoveries was published later.
- Kirkpatrick, J. Davy; Cushing, Michael C.; Gelino, Christopher R.; Griffith, Roger L.; Skrutskie, Michael F.; Marsh, Kenneth A.; Wright, Edward L.; Mainzer, A.; Eisenhardt, Peter R.; McLean, Ian S.; Thompson, Maggie A.; Bauer, James M.; Benford, Dominic J.; Bridge, Carrie R.; Lake, Sean E.; Petty, Sara M.; Stanford, S. A.; Tsai, Chao-Wei; Bailey, Vanessa; Beichman, Charles A.; Bloom, Joshua S.; Bochanski, John J.; Burgasser, Adam J.; Capak, Peter L.; Cruz, Kelle L.; Hinz, Philip M.; Kartaltepe, Jeyhan S.; Knox, Russell P.; Manohar, Swarnima; Masters, Daniel; Morales-Calderon, Maria; Prato, Lisa A.; Rodigas, Timothy J.; Salvato, Mara; Schurr, Steven D.; Scoville, Nicholas Z.; Simcoe, Robert A.; Stapelfeldt, Karl R.; Stern, Daniel; Stock, Nathan D.; Vacca, William D. (2011). "The First Hundred Brown Dwarfs Discovered by the Wide-field Infrared Survey Explorer (WISE)". The Astrophysical Journal Supplement. 197 (2): 19. arXiv: . Bibcode:2011ApJS..197...19K. doi:10.1088/0067-0049/197/2/19.
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why do we need maths in our lives
Math is an important part of our lives because it is everywhere, and understanding mathematical concepts and being able to calculate mathematical problems can help you in a variety of ways. For example, say you want to have the latest Shopkins or Lego^ set. If you earn allowance for doing chores at home and you know how to multiply or add groups of numbers, you can figure out how many weeks it will take you to have enough money to buy the toys you want! On another note, say you want to walk or ride your bike to school and your mom will let you, but you have to calculate how much time it will take you so you can be sure youll arrive on time. You need to know the distance to school from your starting point and the amount of time it takes you to walk and/or bike to school. Once you measure the distance and know how long it takes you to travel per block, you can add or multiply to determine how much time you need to arrive at school on time. With this information, you can impress your mom and you might get to ride your bike or walk to school. Also, your mom just might let you do more things independently because now youve shown her that you can use critical thinking skills to solve problems! In addition to problem-solving to gain things you want, understanding mathematical concepts also helps you understand the world around you.
Math is a science based on logic (what makes sense) and patterns (repeating designs or shapes), which you will find everywhere you look. Your mind is wired to look for patterns to make sense of things in the world; math is the building block for this. Noticing patterns in the world helps your mind process and understand information better and more quickly. Now wouldnt that feel good?
What do going out for dinner, choosing a shampoo, or planning a holiday all have in common? YouБve guessed it: maths. Numerical and logical thinking play a part in each of these everyday activities, and in many others. A good understanding of maths in everyday life is essential for making sense of all the numbers and problems life throws at us. ItБs your birthday and youБve decided to go out for a meal with some friends. While you wonБt be having fried formulas or a side-order of statistics, maths is involved at every stage. Looking down at the menu, you eye up the prices. The restaurant owner has worked out how much she needs to charge for her food by creating a business model detailing the cost of raw ingredients, staff wages and so on. She also has to calculate how these costs might change in the future and how many customers she expects. Many restaurants fail within their first year because of poor mathematical planning. Thankfully this one is still open for business, so you place your order and the chef gets to work.
YouБd better hope he has a good grasp of maths, because understanding measurement, ratio, and proportion can be the difference between something delicious and something that ends up in the dustbin. Turns out youБre in luck, and the food is excellent. You just about make room for dessert and itБs time to split the bill. Who had the pizza? Did you have one drink, or two? Did the waiter add everything up correctly? Being able to perform quick mental calculations will get it sorted in no time Б and percentages help with leaving a tip! Read more about Washing your hair isnБt exactly rocket science, but with so many brands of shampoo out there it can be difficult to decide which to use. You probably just pick one and stick to it, but advertisers often use statistics to get you to switch brands. A typical advertising claim might be Б80 per cent of people prefer our shampoo to their old oneБ Б but what does that actually mean? In what way did they prefer it? What about those who didnБt like it? Without knowing how many people were surveyed and what they were asked, this claim doesnБt really say much. When it comes to statistics, the questions are just as important as the answers. Still, maybe the adverts worked and you decide to buy some new shampoo.
You can get a 250 ml bottle for бе2, or a 400 ml bottle for бе3. 50, but which is better value? Just as with settling the restaurant bill, mental maths is incredibly helpful for getting a good deal. Read more about Even when youБre looking to spend some time in the sun maths in everyday life is all around you, because planning a holiday is all about optimisation. Deciding where to visit is just the first of a whole bunch of questions. When is the best time of year to go? How do I get to the airport on time? Can I fit all these clothes in my suitcase? Answering these questions involves working with numbers Б hotel prices, flight timetables, suitcase volumes Б to come up with the best results. Once you get there, maths still comes in handy. Maths and numbers are universal, so even if you donБt speak the language you can understand prices and times, and mentally converting currencies lets you check whether youБre spending бе1 or бе10. That certainly helps when youБre picking out souvenirs. Read more about ItБs almost impossible to get through a day without using maths in some way, because our world is full of numbers to handle and problems to solve. Studying the maths in everyday life provides you with the tools to make sense of it all, making life that little bit easier. Image Credit:
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Auroral Rocket in Norway
This page contains archived content and is no longer being updated. At the time of publication, it represented the best available science. However, more recent observations and studies may have rendered some content obsolete.
The aurora borealis and aurora australis—the northern and southern lights—are visible manifestations of a connection between the Sun and Earth. Blasts of energy and magnetically charged particles from the Sun are constantly flowing out into space and crashing into the magnetic fields of Earth and other planets. At Earth, that energy stirs up the particles and energy trapped in Earth’s space, or magnetosphere, creating the auroras and disturbing the upper reaches of our atmosphere.
Photographers captured these digital photos of a four-stage Black Brant XII sounding rocket and the aurora borealis (inset) on December 12, 2010, during the NASA-funded Rocket Experiment for Neutral Upwelling (RENU). The rocket was launched from Andøya Rocket Range near Andenes, Norway, and carried instruments about 200 miles (320 kilometers) into the atmosphere to observe the aurora and the associated flow of heat, particles, and electromagnetic energy. The photograph of the aurora was taken from the Kjell Henrickson Observatory in Svalbard, which was under the apogee, or peak, of the rocket’s arc through the sky. The rocket landed in the ocean about 900 miles (1450 km) from the launch site.
The goal of RENU was to measure the flow of particles and heat both into and out of Earth’s upper atmosphere near the North Pole during an auroral event. The solar wind stirs up Earth’s magnetic field and creates electrical currents in the ionosphere. Such disturbances can also heat the atoms of the thermosphere and other atmospheric layers, expanding them and creating extra drag on satellites and spacecraft, shortening their lifespan.
Around Earth’s poles, the magnetic field stretches out from the core of the planet into space and tucks back in at the opposite pole. The place where most of those field lines bunch up poke out of the Earth usually aligns in an auroral oval, where particles and energy from space precipitate and smash into the oxygen and nitrogen in the atmosphere to make the reds, greens, and whites of auroras. The funnel-shaped area inside that auroral oval—the polar cusp—is mostly open to space. RENU launched right into that cusp region to observe the flows of particles and energy both inbound and outbound.
Photographers captured these digital photos of a four-stage Black Brant XII sounding rocket and the aurora borealis on December 12, 2010, during the NASA-funded Rocket Experiment for Neutral Upwelling (RENU). | <urn:uuid:902a76fe-aaac-4c41-9fd8-a37820e78b4b> | 3.59375 | 600 | Knowledge Article | Science & Tech. | 35.536828 | 95,629,966 |
The European Science Foundation's (ESF) European Collaborative Research (EUROCORES) programme EuroMARC is an essential tool to boost European leadership in the planning of international marine coring expeditions and the preparation of IODP (Intergrated Ocean Drilling Program) or IMAGES (International Marine Past Global Change Study) proposals.
The programme consists of seven collaborative research projects with principal investigators from nine countries. The scientific focus is manifold: reconstructions of the meridional overturning circulation in both high and low latitudes and of the spatial and temporal structure of the interglacials peaks and demises are made using thick marine sediment sections. Fossil reef and carbonate mounds cores are extracted to reconstruct sea-level and environmental changes. Current ocean dynamics and sediment fluxes are investigated with the help of sediment traps, and hydrothermal processes of deep biosphere at mid ocean ridges get explored.
But how does coring work and what is actually done on the cruises? International marine coring expeditions are divided into several parts, the pre-, cruise and post-cruise activities. It's crucial to be a hundred percent prepared for the coring, which means to plan way ahead, starting with getting a slot on one of the few coring and drilling ships, obtaining territorial drilling permits, making sure all the required equipment is on board and getting a good scientific team together. "We had organisational meetings even before EuroMARC started" said Catherine Kissel from the French Atomic Energy Commission (CEA) in Gif-sur-Yvette, who was the chief scientist of the AMOCINT (Atlantic Meridional Overturning Circulation during Interglacials) cruise that took place this summer. The chief scientist is in charge of coordinating all the logistics and operations before and on the cruise, which even includes making sure that all the crew members pass their medical exam.
Often, a site survey cruise precedes the main cruise to identify the best spots for the actual coring and to get the drill sites approved by bodies like IODP. In order to map the topography of the seafloor, a multi-beam echo sounder system is used, which is like a fanlike beam covering a huge swath of the seafloor. Additionally, sediment penetrating systems are employed, which shoot signals with varying energy pulses and wave lengths that hit the bottom and are differently reflected depending on the density of the layers, thus giving a detailed impression of the layering of the sediments.
Besides the seismics, autonomous underwater vehicles are often used for more local surveys. "To make sure we won't damage any living ecosystem, we drop an underwater camera to see the nature of the seafloor just around the potential drilling site" explained Gilbert Camoin from CNRS in Aix-en-Provence, who is the chair of EuroMARC's scientific committee as well as the project leader of CHECREEF (The Last Deglacial Sea-Level and Climatic Changes) and investigates coral reefs in both Tahiti and the Great Barrier Reef. Especially in the case of coral reefs, the regulations for drilling are very strict and pictures are taken before and afterwards. "There is no impact at all, when you pull up the pipes, the hole just collapses and it's even impossible to find it again" assured Camoin.
On the main cruise, the coring itself takes place as well as first measurements and part of the sampling, provided the type of ship allows for it. The cores are extracted in different ways, at different water depths and of different lengths, depending on the sediments and the objectives. Short cores of less than 1.5m are often used to drill coral reefs, and if you have high sedimentation rates going back in time you need long cores. Box coring is used for taking surface samples as is the so-called multicores instrument with four short cores, where even the water above the sediment is captured and subsequently the interface analysed. Once a core is on board, its dimensions are measured. Longer cores are cut into segments, then split into two halves, the archive half and the working half, and the first preliminary, non-destructive on-site analyses are made, such as the core description including photos, microbial activity tests and the measurement of the physical properties in a multi-sensor core logger. Then the cores are stored and cooled in containers before undergoing more sampling procedures.
Life on the cruises is rather exceptional: The expeditions are up to two months long and the science is done around the clock - the members of the scientific crew do two four-hour shifts per day. "It's like a small community living and working together, there is a lot of potential to create a good atmosphere from a scientific perspective, but also to find new friends" said Ralph Schneider of Christian-Albrechts-University in Kiel, who is involved in the GLOW (Tropical Temperature History of Global Warming Events) project. Of course, there are also some downsides, as different personalities can clash as well as families and friends need to be left behind for a considerable time. The crew can be as big as a hundred people, comprising of the science crew, technical crew, the crew maintaining the ship - AMOCINT even had five teachers on board who participated in the "Teachers at Sea" program of EGU-IPEV (European Geoscience Union-Institut Paul-Emile Victor).
As not all techniques can be run on board, the sampling is either done in the individual labs or as a joint activity in form of a science sampling party like in Bremen. "Everyone is sampling for everybody. So it's really a collaborative activity with everyone having a different task" explained Camoin. The scientists receive numerous sampling requests from their community and have to divide their labour. If the cores are sampled in different labs, the results are usually shared in order to avoid duplicate sampling.
Marine coring and drilling is a challenging endeavour. Needless to say that a good recovery of the cores is essential - sometimes the sediment is lost when pulling out the core and the so-called core-catcher at the bottom doesn't shut. The prevailing weather conditions are another crucial success factor: storms, for example, make operations nearly impossible. "Depending on the availability of the ship, you might enter into hurricane season and might lose a week of operations" elaborated Schneider. At times, failures of cruises are more man-made and can reach from difficulties in receiving territorial approval before strict deadlines via rescheduling of slots on the coring ships to failed orders of indispensable drilling equipment. All these factors can seriously jeopardise not only the cruise itself, but also entire research projects. Especially newly hired PhD students are highly dependant on the material retrieved from the sea, as they need to obtain data in time.
EuroMARC is a programme in a truly collaborative fashion. "The great benefit for us is to work in a real network, to exchange data, but also to intercalibrate the results among the labs." said Camoin. "EuroMARC is multidisciplinary, multilab, and this is how science works now and it's very enriching for us to collaborate with other people." added Kissel. First fantastic results have been obtained, such as the discovery of the first ever black smoker field at an ultra-slow spreading ridge by the H2DEEP project headed by Rolf-Birger Pedersen from the University of Bergen. Furthermore, new IODP proposals are also on their way.
Global study of world's beaches shows threat to protected areas
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A single factor can reset the immune system of mice to a state likely similar to what it was 500 million years ago, when the first vertebrates emerged.
Scientists at the Max Planck Institute of Immunobiology and Epigenetics (MPI-IE) in Freiburg re-activated expression of an ancient gene, which is not normally expressed in the mammalian immune system, and found that the animals developed a fish-like thymus.
The normal mouse thymus (left) contains only a small fraction of B-cells (red). If the gene FOXN4 is activated, a fish-like thymus with many B-cells develops. This state is likely to have existed about 500 million years ago, at the time when the first vertebrates emerged.
© Max Planck Institute of Immunobiology & Epigenetics
To the researchers surprise, while the mammalian thymus is utilized exclusively for T cell maturation, the reset thymus produced not only T cells, but also served as a maturation site for B cells – a property normally seen only in the thymus of fish. Thus the model could provide an explanation of how the immune system had developed in the course of evolution. The study has been published in Cell Reports.
The adaptive immune response is unique to vertebrates. One of its core organs is the thymus, which exists in all vertebrate species. Epithelial cells in the thymus control the maturation of T-cells, which later fight degenerated or infected body cells.
The gene FOXN1 is responsible for the development of such T-cells in the mammalian thymus. Scientists led by Thomas Boehm, director at the MPI-IE and head of the department for developmental immunology, activated the evolutionary ancestor of FOXN1, called FOXN4, in the thymic epithelial cells of mice. FOXN4 is present in all vertebrates, but appears to play only a role in the maturation of immune cells of jawed fish, such as cat sharks and zebra fish.
“The simultanuous expression of FOXN4 and FOXN1 in the mouse led to a thymus that showed properties as in fish,” said first author Jeremy Swann. Together with earlier results this suggests that the development and function of thymic tissue was originally intitiated by FOXN4. Due to an evolutionary gene duplication, which led to FOXN1, transiently both genes, and finally only FOXN1 were active in the thymus.
To the researchers surprise not only T-cells developed in the thymus of the mice, but also B-cells. Mature B-cells are responsible for antibody production. In mammals, they normally do not mature in the thymus, but in other organs, such as the bone marrow.
“Our studies suggest a plausible scenario for the transition of a bipotent lymphopoietic tissue to a lymphoid organ supporting primarily T cell development,” said Boehm. Since B- and T-cell progenitors can not yet be distinguished, it remains unclear whether the B-cell development is based on the migration of dedicated B-cell precursors to the thymus, or to maturation from a shared T/B progenitor in the thymus itself.
Comparative studies often suggest that the origin of a particular evolutionary innovation must have occurred in an extinct species. „Here, the re-creation and functional analysis of presumed ancestral stages could provide essential insights into the course of such developments," explained Boehm the study approach.
Dr. Thomas Boehm | Max-Planck-Institute
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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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Atmospheric Modelling and Prediction
This chapter is intended to provide the reader with an introduction to the development and application of models of the Earth’s atmospheric flow. It describes a range of past and present methods for solving the equations governing the behaviour of the Earth’s atmosphere. These equations can be cast in predictive form and their solution therefore provides forecasts of the future state of the atmosphere. The governing equations are mathematical expressions of the various conservation laws governing the atmosphere, as a fluid in motion. The equations also allow for the effects of a wide range of forcing mechanisms. Here we mention but a few, such as the differential heating of the sun’s radiation between the equator and the poles, dissipation of momentum, heat and moisture at the Earth’s surface and boundary layer, turbulence in the free atmosphere, the drag on the atmosphere from steep, high or rough terrain, and the profound influence of Earth’s rotation. The complexity of the interaction between the Earth’s atmosphere and the other components of the Earth’s environmental system are illustrated schematically in Fig. 3.1, which shows the coupled atmosphere-ocean-landsurface model, which is the focus of much of this book. Each of the components represented in Fig. 3.1 is a model in its own right and interacts with the atmospheric model in two main ways.
KeywordsTropical Cyclone Atmospheric Modelling Ensemble Member Numerical Weather Prediction Numerical Weather Prediction Model
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Sten Ohlson has extensive experience of research into so-called transient biomolecular binding. Such binding is short-lived-the biomolecules touch each other for a brief moment only. Many of the processes in the human body-in a cell, for instance-occur with the aid of transient binding.
The discovery and understanding of how important binding can be is now paving the way for an entirely new type of drug that will be both more effective and multicompetent and moreover will be less likely than today's drugs to lead to the development of tolerance in patients.
It is above all in three areas that Professor Sten Ohlson envisions major potential for the new technology: cardiovascular diseases, pain, and neurological disorders.
Some multicompetent drugs based on transient interaction are already in use today. One of them is regular aspirin, where acetyl salicylic acid transiently binds to many target structures and thereby works both as a pain reliever and an inflammation alleviator.
At present Sten Ohlson is collaborating with drug companies in the search for substances that can prevent blood clots in connection with heart attacks and stroke.
Sten Ohlson's research on the importance of transient molecular bindings in biological systems is revolutionary, but he maintains that its application is predicated upon other researchers' abandoning old, traditional approaches.
"The greatest obstacle at present, I believe, is getting scientists to begin to think transiently. This is an entirely new way of conceptualizing and understanding the fundamental functions of diseases that affect us and how we can cure them," says Sten Ohlson.
Karin Ekebjär | 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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Study Predicts Decades Of Global Cooling Ahead
A new study out of the United Kingdom predicts the Earth is about to go through a major climatic shift that could mean decades of cooler temperatures and fewer hurricanes hitting the United States.
Scientists at the University of Southampton predict that a cooling of the Atlantic Ocean could cool global temperatures a half a degree Celsius and may offer a “brief respite from the persistent rise of global temperatures,” according to their study.
This cooling phase in the Atlantic will influence “temperature, rainfall, drought and even the frequency of hurricanes in many regions of the world,” says Dr. Gerard McCarthy. The study’s authors based their results on ocean sensor arrays and 100 years of sea-level data.
“Sea-surface temperatures in the Atlantic vary between warm and cold over time-scales of many decades,” said McCarthy, the study’s lead author. “This decadal variability, called the Atlantic Multi-decadal Oscillation (AMO), is a notable feature of the Atlantic Ocean and the climate of the regions it influences.”
“The observations of [AMO] from [sensor arrays], over the past ten years, show that it is declining,” Dr. David Smeed, a co-author, said in a statement. “As a result, we expect the AMO is moving to a negative phase, which will result in cooler surface waters. This is consistent with observations of temperature in the North Atlantic.”
Researchers argue that a negative AMO will bring “drier summers in Britain and Ireland, accelerated sea-level rise along the northeast coast of the United States, and drought in the developing countries of the Sahel region,” according to the study’s press release. Interestingly enough, the study also predicts fewer hurricanes hitting the U.S.– a result of a cooler Atlantic.
Atlantic cooling can impact the climate for decades, according to researchers, on timescales from 20 to 30 years. This means cooler global temperatures and changing weather patterns could unfold over the next two to three decades, possibly extending the so-called “pause” in global warming.
For years, scientists have been debating why satellite temperature data shows there have been about 18 years with no warming trend. Surface temperature data shows a similar pause in warming for the last 10 to 15 years.
So far, the dominant explanation seems to be that oceans have absorbed a lot of the heat that would have otherwise gone into the atmosphere. And most scientists argue the world will continue warming because of increasing greenhouse gas emissions.
Some scientists, however, have been arguing the world is indeed headed for a cooling phase based on solar cycles. Scientists from Germany to India have argued that weakening solar activity could bring about another “Little Ice Age.”
“The stagnation of temperature since 1998 was caused by decreasing solar activity since 1998,” wrote Jürgen Lange Heine, a physicist with the German-based European Institute for Climate and Energy (EIKE).
“From 1900 to 1998, solar radiation increased by 1.3 W / m², but since 1998 it has diminished, and could reach values similar to those of the early 20th century. A drop in global temperature over the next few years is predicted,” Heine wrote.
The Virginia-based Vencore Weather recently reported that “[n]ot since cycle 14 peaked in February 1906 has there been a solar cycle with fewer sunspots.”
We are currently more than six years into Solar Cycle 24 and the current nearly blank sun may signal the end of the solar maximum phase,” Vencore Weather experts noted. “Going back to 1755, there have been only a few solar cycles in the previous 23 that have had a lower number of sunspots during its maximum phase.”
McCarthy and his colleagues, however, argue there could be a reprieve from warming based on natural ocean cycles– not solar activity. The British scientists argue that weaker ocean currents are carrying less heat northward from the tropics.
Content created by The Daily Caller News Foundation is available without charge to any eligible news publisher that can provide a large audience. For licensing opportunities of our original content, please firstname.lastname@example.org. | <urn:uuid:276b3a60-f77e-473e-b815-b6fc71f687a3> | 3.375 | 900 | Truncated | Science & Tech. | 40.675966 | 95,630,044 |
Sentinel-5P sealed from view
4 October 2017
As preparations for the launch of Sentinel-5P continue on track, the team at Russia’s Plesetsk site has bid farewell to the satellite as it was sealed from view in the Rockot fairing. Liftoff is set for 13 October at 09:27 GMT (11:27 CEST).
Since its arrival at the launch site at the beginning of September, Sentinel-5P has been through a series of stringent tests to confirm there was no damage during the flight from the UK.
These tests have made sure that everything is in good working order so that this new satellite will deliver measurement of air quality.
The delicate and risky task of fuelling the satellite took place nearly two weeks ago, after which it was joined to the rocket adapter.
It was then hoisted onto the upper stage and the last protective covers were removed before encapsulation in the rocket fairing, which protects the satellite during the first part of the launch. The next step will be to transfer the ‘Ascent Unit’ to the Rockot on the launch pad, scheduled for Saturday.
Sentinel-5P – the ‘P’ standing for ‘Precursor’ – is the first Copernicus mission dedicated to monitoring our atmosphere. The satellite carries the state-of-the-art Tropomi instrument to map a multitude of trace gases such as nitrogen dioxide, ozone, formaldehyde, sulphur dioxide, methane, carbon monoxide and aerosols – all of which affect the air we breathe and therefore our health, and our climate.
With a swath width of 2600 km, it will map the entire planet every day. Information from this new mission will be used through the Copernicus Atmosphere Monitoring Service for air quality forecasts and for decision-making.
The mission will also contribute to services such as volcanic ash monitoring for aviation safety and for services that warn of high levels of UV radiation, which can cause skin damage.
In addition, scientists will also use the measurements to improve our knowledge of important processes in the atmosphere related to the climate and to the formation of holes in the ozone layer. | <urn:uuid:c4fcfdfb-e748-41e5-8009-a93e65be3ef5> | 2.53125 | 445 | News (Org.) | Science & Tech. | 38.346934 | 95,630,056 |
posted by kelsey
A 8 kg crate is placed at rest on an incline plane (s=0.8, k=0.5), whose angle is 60o. It then slides 3 m down the incline.
work done by gravity: ?J
work done by friction force: ?J
Using your results from part a, find the speed of the crate after sliding this distance.
The normal force on the plane from weight is mgCosTheta. The component of force due to weight down the plane is mgSinTheta.
Work down the plane is Ffriction*distance, or mg*mu*SinTheta*distance.
Work done by gravity is mg*distancedownplane*SinTheta Think that out... | <urn:uuid:f7c3499d-c8c5-4dad-92b7-2e6054b2d09c> | 3.1875 | 158 | Q&A Forum | Science & Tech. | 81.808352 | 95,630,069 |
Status: Not Listed
Common loons, with their eerie calls, are icons of northern lakes. These long-bodied birds are impressive swimmers and divers. Unlike the majority of bird species, common loons have solid bones, which makes them less buoyant and more effective at maneuvering through water. Their legs are set far back on their bodies, which also helps them maneuver through water, but causes them to move awkwardly on land. The common loon spends little time on land though, typically only going ashore to nest.
The loon can stay underwater for up to five minutes, its signature red eyes helping it locate prey while submerged. Common loons are skilled in flight, sometimes reaching speeds of 70 miles (110 kilometers) an hour. Because of their relatively heavy bodies, they need a long "runway" to take off for flight and can only do so from water. Their legs trail out behind them while in flight, a characteristic held by all loons.
During the summer breeding months, adults have a black rounded head, pointed black bill, black-and-white barred neck, white breast, and a black-and-white checkered back. From September to March, however, their throat is white and the rest of their body is gray. Common loons reach a size of 28 to 32 inches (71 to 81 centimeters) in length with a wingspan of about 46 inches (117 centimeters). They can weigh between 9 and 12 pounds (4 and 5.5 kilograms). Males are generally larger than females.
Common loons breed on lakes surrounded by forests in Canada and the northern United States, including Alaska. In the winter they migrate from northern lakes to coastal ocean waters.
Adult loons are rarely prey for other species, with the possible exception of sea otters and large raptors such as bald eagles and ospreys. However, their eggs and chicks are eaten by raccoons, ravens, bald eagles, minks, gulls, crows, snapping turtles, skunks, foxes, northern pike, and muskies.
The common loon feeds primarily on fish. Common loons will often consume their prey underwater, instead of bringing it to the surface to eat. They will also eat a variety of other aquatic animals, such as crayfish and shrimp, as well as vegetation.
Common loons are thought to be monogamous, having the same partner for life. Male and female common loons will prepare a nest of grasses and reeds together in a sheltered location along a lakeshore, or on an island near deep water where they can swim to and from the nest without alerting predators. They incubate one to two eggs for 26 to 30 days. Within hours of hatching, chicks are able to swim and ride on their parents’ backs. The nesting pair will often return to an existing nest the next year. Loons begin breeding at about six years old and are thought to be long-lived birds, living up to 30 years.
North American common loon populations are stable overall. They depend on clean water in lakes and other bodies of water, and are sensitive to the effects of pollution and human disturbances. They have special conservation status in some states, such as Michigan, where they are listed as threatened.
Common loons have four different calls, each used for a different purpose.
Animal Diversity Web, University of Michigan Museum of Zoology
Common Loon Migration Study, Upper Midwest Environmental Sciences Center, United States Geological Survey
Michigan’s Special Animals, Michigan Natural Features Inventory
Minnesota Department of Natural Resources
Sibley, David. The Sibley Guide to Birds. New York: Alfred A. Knopf, 2000. Print.
The Cornell Lab of Ornithology
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:6626b36a-3174-4972-a33b-076a2786c531> | 3.671875 | 922 | Knowledge Article | Science & Tech. | 50.407011 | 95,630,086 |
It could be because they display a horizontal diurnal migration
pattern like some hydro- and scyphomedusae (Hamner and Hauri, 1981; Arkett, 1989; Hamner et al.
The fish, in their turn, carried out the opposite diurnal migration
, feeding in the surface layers in the mornings and moving to intermediate depths later in the day and at night.
Vertical distribution and diurnal migration
patterns of Jasus edwardsii phyllosomas off the east coast of the North Island, New Zealand.
of plankton in the Gulf of Maine and its correlation with changes in submarine irradiation. | <urn:uuid:c908bf55-030e-484d-9223-b25060176faa> | 2.984375 | 133 | Knowledge Article | Science & Tech. | 38.715179 | 95,630,088 |
By Jürgen Jost
The major goal of this ebook is to explain and enhance the conceptual, structural and summary considering arithmetic. particular mathematical constructions are used to demonstrate the conceptual process; offering a deeper perception into mutual relationships and summary universal gains. those rules are conscientiously prompted, defined and illustrated via examples in order that the various extra technical proofs might be passed over. The booklet can as a result be used:
· easily as an outline of the landscape of mathematical constructions and the family among them, to be supplemented via extra precise texts everytime you are looking to collect a operating wisdom of a few structure
· on its own as a primary creation to summary mathematics
· including latest textbooks, to place their effects right into a extra common perspective
· to achieve a brand new and expectantly deeper viewpoint after having studied such textbooks
Mathematical Concepts has a broader scope and is much less specific than normal mathematical textbooks in order that the reader can effectively snatch the fundamental suggestions and ideas for person wishes. it is going to be appropriate for complicated mathematicians, postgraduate scholars and for scientists from different fields with a few history in formal reasoning.
Read Online or Download Mathematical Concepts PDF
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The term ‘chaos’ is used in reference to unstable, aperiodic motion in dynamical systems and also to the state of a system which exhibits such motion. Almost any nonequilibrium open system will, when some bifurcation parameter characterizing the system is made sufficiently large, display chaotic behavior. It can be said that chaos is Nature’s universal dynamical form. Chaos is characterized by the coexistence of an infinite number of unstable periodic orbits that determine the form and structure of the chaotic behavior exhibited by any given system. In this chapter we consider the problem of identifying the descriptive signature of such a set of orbits, and we establish the point of view from which we will elucidate the nature of chaos.
KeywordsPeriodic Orbit Invariant Manifold Unstable Manifold Chaotic Attractor Fluid Particle
Unable to display preview. Download preview PDF.
- Baker, G.L., Gollub, J.P. (1990) Chaotic Dynamics, An Introduction. Cambridge University Press, New YorkGoogle Scholar
- Berge, P., Pomeau, Y., Vidal, C. (1984) Order Within Chaos. Hermann, Paris Eckmann, J.-P., Ruelle, D. (1985) Ergodic theory of chaos and strange attractors. Rev. Mod. Phys. 57, 617–656Google Scholar
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- Wiggins, S. (1992) Chaotic transport in dynamical systems. Springer, Berlin, HeidelbergGoogle Scholar | <urn:uuid:e95dbeb2-5c3b-4c55-a0cd-aeaab7745eab> | 2.78125 | 488 | Truncated | Science & Tech. | 49.170817 | 95,630,098 |
On Monday evening the Climate Engineering Conference (CEC17) was opened in Berlin by Mark Lawrence, Scientific Director at the Institute for Advanced Sustainability Studies (IASS). The international conference explores the potentials and risks of possible measures to intervene in the climate system. Over four days, experts from academia, political institutions, and civil society are engaging in intensive debates about the study, risks, and governance of geoengineering.
The international community has set itself ambitious climate goals in the Paris Agreement. But how can those goals be achieved? The Intergovernmental Panel on Climate Change (IPCC) assumes that in addition to reducing greenhouse gas emissions to almost zero, massive quantities of carbon dioxide will need to be removed from the atmosphere by the year 2100.
“It will be very difficult to achieve the Paris Agreement targets without resorting to some form of climate engineering. So we urgently need an open and critical debate on the different forms and consequences of such interventions in the climate system,” said Mark Lawrence at the opening of the conference.
A forum for international, critical and transparent exchange
With this in mind, the climate engineering research team at the IASS invited around 250 experts to this year’s Climate Engineering Conference in Berlin. “The CEC17 is probably the most important platform for the global, critical, and transparent exchange of ideas on this highly controversial issue,” explained Stefan Schäfer, head of the Climate Engineering project at the IASS and one of the conference organisers.
The conference participants include researchers, policymakers and civil society actors, all of whom bring very different views and perspectives to the table. CEC17 brings the scientists conducting research into climate engineering face to face with environmental activists and political actors. Around fifty participants have travelled to the conference from developing countries and emerging economies. They are also due to participate in a meeting of the Solar Radiation Management Governance Initiative (SRMGI) organised on the sidelines of the conference.
Discussion of planned solar radiation management field experiment
The question of whether research should leave the laboratory is a major bone of contention in discussions of geoengineering. At CEC17 Harvard University physicist David Keith will discuss his planned field experiment and the governance activities associated with it (Wednesday at 2 pm).
In over thirty further conference events the focus will be on carbon dioxide removal (CDR) and solar radiation management (SRM) measures. Among other things, participants will discuss whether the Paris Agreement goals can be achieved without climate engineering (Tuesday at 11 am), how climate policy should deal with the propagators of fake news (“Trumped!”, Wednesday at 9 am), and what rules should be set for research in a code of conduct (Thursday, 2 pm). Interactive events like the game “To Gabon or not to Gabon” (Tuesday at 4 pm) are designed to encourage an open exchange of views.
Politically relevant: Developing international governance
For Mark Lawrence, there is an urgent need for internationally binding rules in this area: “At the IASS we are elaborating concepts for the governance of climate engineering and also advise political actors on how they can develop corresponding measures.” The question of how geoengineering is perceived in the political sphere is another major theme of CEC17. Janos Pasztor, Executive Director of the Carnegie Climate Geoengineering Governance Initiative (C2G2) and former climate advisor to UN Secretary General Ban Ki-moon, is also playing an active role at the conference.
Like its predecessor held in 2014, this Climate Engineering Conference is organised by the Institute for Advanced Sustainability Studies (IASS), Potsdam. The conference partners are the Haus der Kulturen der Welt (HKW) and the SRMGI and C2G2 initiatives. The CEC17 media partner is Der Tagespiegel.
The conference programme and press kit can be found at http://www.ce-conference.org/
Twitter hashtag #DiscussCEC
Statements of speakers at the press briefing on 10 October
Lili Fuhr, Heinrich Böll Foundation
“To limit global temperature rise to 1.5°C we must be prepared to follow radical emissions reduction pathways that go far beyond conventional economic thinking. They include a politically driven premature phase-out of fossil fuels, sustainable peasant agriculture, and absolute reductions in global resource and energy consumption through circular-economy and zero-waste approaches. Proven and locally adapted technologies that support these objectives already exist. We also need to act to restore our ecosystems, first and foremost our rainforests, moors and oceans. If we’re serious about engaging in a rigorous discussion of ecologically sustainable and socially just alternatives to confront the root causes of climate change, then there is no reason to believe that geoengineering is needed.”
David Keith, Harvard University
“Cutting emissions to zero is necessary to enable a stable climate. It’s possible to make very fast emissions cuts while preserving energy services for the wealthy and increasing access for the poor. However, even the immediate elimination of emissions does not eliminate climate risks; it simply stops the accumulation of carbon and thus the increase in climate impacts. In my view, solar geoengineering is – at best – a supplement to emissions cuts, not a substitute for them. It is possible that a combination of emissions cuts, carbon removal, and solar geoengineering could provide a significantly safer climate than emissions cuts alone or emissions cuts and carbon removal combined. Possible but unproven. The central political challenge is how to learn more about solar geoengineering – a potentially useful and potentially dangerous technology – given that research will likely be overhyped and exploited by forces opposed to emissions cuts.”
Pablo Suarez, Red Cross Red Crescent Climate Centre
“The humanitarian sector is active at the global frontline of climate impacts. Geoengineering is a humanitarian concern: The potential for deliberate large-scale intervention in the Earth’s climate system has major implications in terms of impacts on the most vulnerable. Those who can suffer the worst outcomes need to be involved, especially given the plausibility of ‘predatory geoengineering’, where recklessly self-concerned actions may result in harmful consequences to others. It is imperative to link science, policy and humanitarian practice, creating a geoengineering risk-management framework to ensure that the interests of the most vulnerable are considered and addressed.”
For further information or to arrange an interview, please contact
Eva Söderman / Anja Krieger
Press & Communications
Institute for Advanced Sustainability Studies e.V. (IASS)
Berliner Straße 130, 14467 Potsdam
Tel. +49 (0)331 288 22-340/479
Fax +49 (0)331 288 22-310
E-mail firstname.lastname@example.org / email@example.com
The Institute for Advanced Sustainability Studies (IASS) conducts research with the goal of identifying, advancing, and guiding transformation processes towards sustainable societies in Germany and abroad. Its research practice is transdisciplinary, transformative, and co-creative. The institute cooperates with partners in academia, political institutions, administrations, civil society, and the business community to understand sustainability challenges and generate potential solutions. A strong network of national and international partners supports the work of the institute. Among its central research topics are the energy transition, emerging technologies, climate change, air quality, systemic risks, governance and participation, and cultures of transformation. The IASS is funded by the research ministries of the Federal Government of Germany and the State of Brandenburg.
Eva Söderman | idw - Informationsdienst Wissenschaft
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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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James C. O'Shaughnessy
Robert W. Thompson
John A. Bergendahl
Many parts of the world are facing water crises due to the lack of clean drinking water. Growing industrialization in many areas and extensive use of chemicals for various concerns has increased the burden of deleterious contaminants in drinking water especially in developing countries. It is reported that nearly half of the population in developing countries suffers from health problems associated with lack of potable drinking water as well as the presence of microbiologically contaminated water . Synthetic and natural organic contaminants are considered among the most undesirable contaminants found in water. Various treatment processes are applied for the removal of organic contaminants from water including reverse osmosis membranes, ion exchange, oxidation, nanofiltration, and adsorption. The adsorption process is a widely-used technology for the removal of organic compounds from water. In this work, the adsorption of chloroform and methyl tertiary butyl ether (MTBE) onto granular zeolites was investigated. Zeolites were specifically chosen because they have shown higher efficiency in removing certain organics from water than granular activated carbon (GAC). Batch adsorption experiments to evaluate the effectiveness of several granular zeolites for the removal of MTBE and chloroform from water were conducted and the results compared with GAC performance. Results of these batch equilibrium experiments showed that ZSM-5 was the granular zeolite adsorbent with the greatest removal capacity for MTBE and chloroform from water, and outperformed GAC. Fixed-bed adsorption experiments with MTBE and chloroform were performed using granular ZSM-5. Breakthrough curves obtained from these column experiments were used to understand and predict the dynamic behavior of fixed bed adsorbers with granular ZSM-5. The ii film pore and surface diffusion model (FPSDM) was fit to the breakthrough curve data obtained from the fixed bed adsorption experiments. The FPSDM model takes into account the effects of axial dispersion, film diffusion, and intraparticle diffusion mechanisms during fixed bed adsorption. Generally, good agreement was obtained between the FPSDM simulated results and experimental breakthrough profiles. This study demonstrated that film diffusion is the primary controlling mass transfer mechanism and therefore must be accurately determined for good breakthrough predictions.
Worcester Polytechnic Institute
Civil & Environmental Engineering
All authors have granted to WPI a nonexclusive royalty-free license to distribute copies of the work. Copyright is held by the author or authors, with all rights reserved, unless otherwise noted. If you have any questions, please contact email@example.com.
abu-lail, l. I. (2011). removal of chloroform and MTBE from water by adsorption onto granular zeolites: equilibrium, kinetic, and mathematical modeling study. Retrieved from https://digitalcommons.wpi.edu/etd-dissertations/7
zeolites, adsorption, mathematical modeling, MTBE, chloroform | <urn:uuid:56354e99-97c5-4a7d-ab5e-d7db7246f983> | 2.59375 | 635 | Academic Writing | Science & Tech. | 19.485362 | 95,630,112 |
While many social insects have distinct social classes that differ in appearance and are fixed from birth, paper wasp society is more fluid — all castes look alike, and any female can climb the social ladder and become a queen. Now, molecular analysis reveals that paper wasp social hierarchy is less flexible than it appears. Queens diverge from their lower-status sisters long before they reach adulthood, scientists say.
Slender reddish-brown wasps with black wings, Polistes metricus paper wasps are a common sight throughout the Midwestern and Southeastern U.S. Hidden in papery umbrella-shaped nests in the eaves and rafters of your house, a complex society is hard at work.
Female wasps develop into one of two castes that take on different roles within the nest. While young queens don't work and eventually leave the nest to reproduce and rule colonies of their own, workers forego reproduction and spend their lives defending the nest and raising their siblings.
"All offspring look alike but some work and some don't," said lead author James Hunt, currently a visiting scholar at the National Evolutionary Synthesis Center in Durham, NC. "The workers are the ones that fly out and sting you if they feel their colony is threatened."
Hunt and his colleagues wanted to find out if hidden molecular mechanisms set some paper wasps on the path to becoming workers, and others to becoming queens. "Many scientists think that paper wasp social status isn't decided until they are adults, but some think there is more to it than that," said Hunt, also a biologist at North Carolina State University.
With co-authors Amy Toth and Tom Newman at the University of Illinois and Gro Amdam and Florian Wolschin at Arizona State University, the researchers measured gene activity and protein levels in young paper wasp larvae before they took on different roles.
Although all wasp larvae look and act alike, the researchers discovered several differences during development that predispose them to one caste or the other.
The larvae that become queens have high levels of a group of proteins that enable them to survive the winter and reproduce next year, whereas the ones that become workers are much shorter-lived and have low levels of these proteins, said Hunt. "There's less upward mobility in the ones that become the workers. They may look just like the future queens, but they are strongly biased toward the worker role."
Future queens also showed higher activity of several genes involved in caste determination in other, more recently evolved insects that have more visible distinctions between castes. "Paper wasps and honey bees are separated by 100 million years of evolution, but we see some of the same gene and protein patterns in paper wasps that lead to different types of adults in bees," he explained.
The results help shed light on how insect social behavior comes to be, Hunt explained. "It is sometimes argued that adult wasps actually choose to become workers in order to help their mother reproduce and raise their sisters — hence the term 'altruistic,'" he said. "What we found is that really the choice is limited by how they develop as larvae."
The team's findings were published online in the May 17 issue of PLoS ONE.
Michael Henshaw of Grand Valley State University was also an author on this study.
CITATION: Hunt, J., F. Wolschin, et al. (2010). "Differential gene expression and protein abundance evince ontogenetic bias toward castes in a primitively social wasp." PLoS ONE. http://dx.plos.org/10.1371/journal.pone.0010674.
The National Evolutionary Synthesis Center (NESCent) is a nonprofit science center dedicated to cross-disciplinary research in evolution. Funded by the National Science Foundation, NESCent is jointly operated by Duke University, The University of North Carolina at Chapel Hill, and North Carolina State University.
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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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12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
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16.07.2018 | Earth Sciences | <urn:uuid:a961be2e-84f2-43ba-9598-ee20ca622125> | 3.3125 | 1,457 | Content Listing | Science & Tech. | 42.629117 | 95,630,122 |
Saturn’s moon Titan may be nearly a billion miles away from Earth, but a recently published paper based on data from NASA’s Cassini spacecraft reveals a new way this distant world and our own are eerily similar. Just as the surface of oceans on Earth lies at an average elevation that we call “sea level,” Titan’s seas also lie at an average elevation.
This is the latest finding that shows remarkable similarities between Earth and Titan, the only other world we know of in our solar system that has stable liquid on its surface. The twist at Titan is that its lakes and seas are filled with hydrocarbons rather than liquid water, and water ice overlain by a layer of solid organic material serves as the bedrock surrounding these lakes and seas.
The new paper, led by Alex Hayes at Cornell University in Ithaca, New York, and published in the journal Geophysical Research Letters, finds that Titan’s seas follow a constant elevation relative to Titan’s gravitational pull — just like Earth’s oceans. Smaller lakes on Titan, it turns out, appear at elevations several hundred feet, or meters, higher than Titan’s sea level. Lakes at high elevation are commonly found on Earth. The highest lake navigable by large ships, Lake Titicaca, is over 12,000 feet [3,700 meters] above sea level.
The new study suggests that elevation is important because Titan’s liquid bodies appear to be connected under the surface in something akin to an aquifer system at Earth. Hydrocarbons appear to be flowing underneath Titan’s surface similar to the way water flows through underground porous rock or gravel on Earth, so that nearby lakes communicate with each other and share a common liquid level.
The paper was based on data obtained by Cassini’s radar instrument until just months before the spacecraft burned up in the Saturn atmosphere last year. It also used a new topographical map published in the same issue of Geophysical Research Letters.
- P. Corlies, et al., “Titan’s Topography and Shape at the End of the Cassini Mission,” Geophysical Research Letters, 2017; DOI: 10.1002/2017GL075518
- A. G. Hayes, et al., “Topographic Constraints on the Evolution and Connectivity of Titan’s Lacustrine Basins,” Geophysical Research Letters, 2017; DOI: 10.1002/2017GL075468
Source: Jia-Rui Cook, Jet Propulsion Laboratory | <urn:uuid:d2e0537b-82bb-4d98-bff7-934fe3dde568> | 3.796875 | 536 | News Article | Science & Tech. | 45.307982 | 95,630,134 |
A research team from the University of the Basque Country have analysed the substances that are triggered in plants to protect themselves, with the goal of choosing the species that is best suited to the environment during reforestation under adverse environmental conditions.
Droughts, extreme temperatures, contamination, and so on – all are harmful to plants. On occasions, the damage is caused by humans. For example, as a consequence of cutting down trees, plants used to shady conditions may be exposed to an excess of light. However, in most cases it is nature itself that causes the stress. In spring, plants have sufficient average humidity and temperatures, i.e. what scientists deem ‘optimum conditions’.
But in winter they have to withstand considerable cold and in summer, on the other hand, high temperatures and droughts: adverse environmental factors that generate stress situations. Thus, in winter and in summer, the light which under normal conditions would be a source of energy becomes excessive, given that the metabolism of the plants under these conditions is not able to assimilate it. This process is known as photo-oxidative stress.
Some plants are incapable of withstanding this stress – unable to dissipate the excess energy, generating a chain reaction by which they deteriorate and die. Other species, on the other hand, undergo processes of acclimatising themselves to the new situation and trigger chemical compounds that act to protect them. These species are the object of interest of a research team from the Department of Plant Biology and Ecology at the Faculty of Science and Technology of the University of the Basque Country (UPV/EHU).
The members of this team – called EKOFISKO and led by Dr. Txema Becerril – are studying the plants’ defence mechanisms in order to predict damage before it is produced. They measure the photo-protector substances created by the plants and analyse their behaviour, using them as biosensors of photo-oxidative stress.
Amongst all these plants, they have been studying trees and other forest species, given that they are long-cycle species and it is important that they acclimatize correctly to the environment before reforestation is embarked upon. The autochthonous species of the Autonomous Community of the Basque Country (CAPV), especially the southern part thereof, being where the two climatic regions - the Atlantic and the Mediterranean – meet, would be the first to suffer the consequences of climate change. The study mainly involves species with ecological, economic or landscape interest, and analyses both the deciduous species and the perennial varieties; particularly the latter as they withstand the cold winter temperatures without shedding their leaves.
On the trail of the box tree
The box is a model species and a good example for analysing the defence mechanisms of plants: it is capable of withstanding quite different environments (both dry and sunny climes as well as damp and shaded conditions), thanks to its resistance and adaptability. When it is under stress, the leaves go red, as other species do in autumn, but its peculiarity is that it is able to convert its chromoplasts (where the red pigments accumulate) into chloroplasts (with green pigments) and once again capture energy when the stress conditions disappear.
In order to measure the biomarkers of photo-oxidative stress the research team also simulated the winter or summer conditions in the greenhouse and in the growing rooms at the Faculty of Science and Technology, i.e. they artificially induced in the plants the conditions which they would have to be subjected. This makes it possible to isolate each one of the stress agents and to study its consequences, leaving aside the rest of the variables found in nature.
According to what the research team at the UPV/EHU have shown, the secret to being the most adaptable species lies in accumulating antioxidants, such as vitamin E and special carotenoids (carotenes and xantophylls); precisely the substances that provide colour to plants. On receiving too much light, the VAZ cycle is triggered and the balance between three xantophylls (corresponding to these 3 initials) is altered so that the excess energy does not harm the plants.
The human body, for example, is not capable of creating these highly important substances itself and it has to ingest vegetables in order to obtain antioxidants (from plants). Besides studying the VAZ cycle, Mr Txema Becerril’s team has contributed to the discovery of a new cycle (the lutein epoxide cycle), present in many forest species such as beech, laurel, holm oak or oak and the team is currently studying what exactly is its protective function.
Alaitz Ochoa de Eribe | alfa
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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In these girth-conscious times, even weight itself has weight issues. The kilogram is getting lighter, scientists say, sowing potential confusion over a range of scientific endeavor.
The kilogram is defined by a platinum-iridium cylinder, cast in England in 1889. No one knows why it is shedding weight, at least in comparison with other reference weights, but the change has spurred an international search for a more stable definition.
''It's certainly not helpful to have a standard that keeps changing,'' says Peter Becker, a scientist at the Federal Standards Laboratory here, an institution of 1,500 scientists dedicated entirely to improving the ability to measure things precisely.
Even the apparent change of 50 micrograms in the kilogram -- less than the weight of a grain of salt -- is enough to distort careful scientific calculations.
Dr. Becker is leading a team of international researchers seeking to redefine the kilogram as a number of atoms of a selected element. Other scientists, including researchers at the National Institute of Standards and Technology in Washington, are developing a competing technology to define the kilogram using a complex mechanism known as the watt balance.Continue reading the main story
The final recommendation will be made by the International Committee on Weights and Measures, a body created by international treaty in 1875. The agency guards the international reference kilogram and keeps it in a heavily guarded safe in a château outside Paris. It is visited once a year, under heavy security, by the only three people to have keys to the safe. The weight change has been noted on the occasions it has been removed for measurement.
''It's part ceremony and part obligation,'' Dr. Richard Davis, head of the mass section at the research arm of the international committee.
''You'd have to amend the treaty if you didn't do it this way.''
That ceremony has become a little sorrowful as the guest of honor appears to be, on a microscopic level at least, wasting away.
The race is already well under way to determine a new standard, although at a measured pace, since creating reliable measurements is such painstaking work.
The kilogram is the only one of the seven base units of measurement that still retain its 19th-century definition. Over the years, scientists have redefined units like the meter (first based on the earth's circumference) and the second (conceived as a fraction of a day). The meter is now the distance light travels in one-299,792,458th of a second, and a second is the time it takes for a cesium atom to vibrate 9,192,631,770 times. Each can be measured with remarkable precision, and, equally important, can be reproduced anywhere.
The kilogram was conceived to be the mass of a liter of water, but accurately measuring a liter of water proved to be very difficult. Instead, an English goldsmith was hired to make a platinum-iridium cylinder that would be used to define the kilogram.
One reason the kilogram has lagged behind the other units is that there has been no immediate practical benefit to increasing its precision. Nonetheless, the drift in the kilogram's weight carries over to other measurements. The volt, for example, is defined in terms of the kilogram, so a stable kilogram definition will allow the volt to be tied more closely to the base units of measure.
A total of 80 copies of the reference kilogram have been created and distributed to signatories of the metric treaty. The sometimes colorful history of these small metal cylinders underscores how long the world has used the same definition of the kilogram.
Some of the metal plugs were issued to countries that later vanished, including Serbia and the Dutch East Indies. The Japanese had to surrender theirs after World War II. Germany has acquired several weights, including the one issued to Bavaria in 1889 and the one that belonged to East Germany.
To update the kilogram, Germany is working with scientists from countries including Australia, Italy and Japan to produce a perfectly round one-kilogram silicon crystal. The idea is that by knowing exactly what atoms are in the crystal, how far apart they are and the size of the ball, the number of atoms in the ball can be calculated. That number then becomes the definition of a kilogram.
To separate the three isotopes of silicon, Dr. Becker and his team are turning to old nuclear weapons factories from the Soviet Union, where centrifuges once used to produce highly enriched uranium are able to produce the required purity of silicon.
''We need so many nines,'' Dr. Becker said, and Soviet uranium processors are one of the only places to get them. ''With the Russians, we're getting about four of them,'' or 99.99 percent pure silicon 28.
A test crystal has already been produced, and Dr. Arnold Nicolaus, another scientist at the German standards laboratory, is responsible for measuring whether it is perfectly round. He has measured the crystal in a half-million places to determine its shape.
It's probably the roundest item ever made by hand. ''If the earth were this round, Mount Everest would be four meters tall,'' Dr. Nicolaus said. An intriguing characteristic of this smooth ball is that there is no way to tell whether it is spinning or at rest. Only if a grain of dust lands on the surface is there something for the eye to track.
Scientists from the United States, England, France and Switzerland say the challenge of calculating the precise number of atoms in a silicon crystal is too imprecise with today's technology so they are refining a technique to calculate the kilogram using voltage.
''Measuring energy is easier than counting atoms,'' said Dr. Richard Steiner, a scientist at the National Institute of Standards and Technology in Washington, who is leading the international project to create the watt scale.
In the last few weeks, he has reported that his experiments have yielded data that are close to what they need. ''Now we're into the picayune, itsy-bitsy errors,'' he said, having recently corrected ''totally ridiculous'' errors of 100 parts per million.
The idea of the watt balance is to measure the electromagnetic force needed to balance a reference kilogram. As long as the gravitational field is precisely known for the location of the experiment, the mass on the scale can be related to power. (The gravitational field is a complicated calculation that needs among other things constantly updated changes in tidal forces.)
The definition of the kilogram would then be a measurement of that power or in terms of something that could be derived from it, like the mass of an electron. The experiment in Washington is occurring in a large three-story structure, but in spite of the complexity and circuitous route of calculating mass, Dr. Steiner says he is confident that his team will have persuasive data shortly.
''In the short term, I think we'll win,'' he said.
Dr. Davis, who is working closely with those making the final decision about the fate of the kilogram, says he is not so sure. ''In terms of published results, the watt balance is closer of the two,'' he said. ''But it's very hard to say which is better.''
Many scientists believe that the most elegant way to define the kilogram is by counting out a kilo's worth of atoms of an element. A project is under way to test that with gold atoms. But the sheer number of atoms in a kilogram, a number with roughly 25 digits in it, makes that approach unfeasible for the foreseeable future.
For now, Dr. Davis is willing to set his sights lower in the error-prone world of superprecision measurements. ''It would be nice,'' he said, ''just to have two experiments in the world that agreed with each other.''
Correction: May 30, 2003, Friday An article in Science Times on Tuesday about efforts to set a new standard for the kilogram referred imprecisely to the platinum-iridium cylinder that now defines it. The cylinder represents a unit of mass, not weight. (Mass is the amount of matter in an object; weight is the force exerted by gravity on a mass.)Continue reading the main story | <urn:uuid:aa4b1389-7c23-4851-9b29-89f428fd266a> | 3.078125 | 1,681 | Truncated | Science & Tech. | 45.270243 | 95,630,148 |
about this item
Ultraviolet-B radiation (UV-B) has profound effects on plant growth and development, and exposure varies with ozone depletion across geographic regions with ecosystem and agricultural consequences. This book deals with large-scale impacts and how UV-B affects plants at the molecular level. The UV-B photoreceptor of plants has only recently been characterized. While UV-B radiation can be damaging, it also has a more positive role in plant photomorphogenesis. Consequently, UV-B treatments are being developed as innovative approaches to improve horticulture. This book is a timely synthesis of what we know and need to know about UV-B radiation and plants.
Number of Pages: 182
Publisher: Stylus Pub Llc
Street Date: November 16, 2017
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The X Prize's New Frontier: Genomics
The $10-million prize could spur the advent of cheaper, faster DNA sequencing and personalized medicine.
A new race in human genome sequencing was launched yesterday–this time to see who can sequence genomes the fastest. The X Prize Foundation has just announced a $10-million award for the first privately funded team that can sequence 100 human genomes in 10 days. The same foundation sponsored the 2004 Ansari X Prize to develop a rocket for private space travel.
In addition to spurring the development of new sequencing technologies, the foundation hopes to bring attention to the ethical and legal issues of personal genomics, by sequencing the genomes of well-known people, including astrophysicist Stephen Hawking, Microsoft cofounder Paul Allen, and Google cofounder Larry Page.
Experts say that rapid gene sequencing technologies are also the key to personalized medicine: the ability to tailor medical treatments to an individual’s genetic profile. “It’s not far-fetched to think of a day when a standard part of your medical care is to determine your genome sequence,” says Francis Collins, director of the National Human Genome Research Institute (NHGRI) and leader of the Human Genome Project, the multi-billion-dollar, federally funded effort that released the first human genome sequence in 2003.
Researchers now want to sequence individuals’ DNA. Collins and others hope that such genomic information could inform doctors of the best drugs or doses for each patient.
While scientists have made rapid advances in genome sequencing–reading one letter of a genome now costs one-tenth of a cent, down from $10 in 1990–the process is still too slow and expensive for common use. “To achieve the goal of the prize, we have another factor of a thousand to go,” says Collins. “It’s a goal you can imagine being achieved–but it’s also going to be quite a stretch.”
Entirely new technologies are likely required to reach the goal of 100 genomes in 10 days, according to experts who spoke at a press conference yesterday in Washington, D.C. “Prizes allow a level of risk-taking that governments might not be able to do,” said X Prize founder Peter Diamandis. (Some new technologies are already in the works; see “Finding the Hidden Mutations That Control Cancer,” June 2006, “Deciphering DNA, Top Speed,” May 2005, and one of our 2006 TR35 winners.)
While everyone’s genome is 99.9 percent identical, small differences contribute to an individual’s risk of complex diseases, such as Alzheimer’s, diabetes, or depression. “We need databases of literally millions of human genomes and concomitant clinical information to decipher the influences of nature and nurture,” says Craig Venter, a scientific advisor for the prize.
Databases of human genomes could also speed up drug development, by showing scientists what molecules to target and allowing them to test new drugs in groups genetically selected to be the most likely to respond.
Experts hope the prize will also bring public awareness to the legal and ethical issues that might arise when genome sequences become a common part of an individual’s medical records. “It will open all sorts of new debates about privacy and ethics, debates Congress ought to have,” says Billy Tauzin, a former congressman and lobbyist for the pharmaceutical industry. A bill prohibiting discrimination based on genetic information was passed in the U.S. Senate two years ago, but has not yet come up for vote in the House.
The X Prize project will have a number of celebrity participants–an addition perhaps designed to make up for the fact that rapid genome sequencing doesn’t have the inherent excitement of a rocket launch. The first group to meet the goal of 100 genomes in 10 days will sequence an additional 100 genomes, including the DNA of celebrities and members of the public chosen by patient-advocacy groups. One of the first volunteers was Stephen Hawking, who suffers from Amyotrophic lateral sclerosis, a debilitating neurological disease thought to have genetic roots.
Couldn't make it to EmTech Next to meet experts in AI, Robotics and the Economy?Go behind the scenes and check out our video | <urn:uuid:4e8ace40-dcb6-4305-a779-5092922256a0> | 2.734375 | 885 | Truncated | Science & Tech. | 36.649828 | 95,630,150 |
|Paradigm||multi-paradigm: functional, imperative|
|Typing discipline||strong, static, inferred|
|MLKit, MLton, MLWorks, Moscow ML, Poly/ML, SML/NJ, MLj, SML.NET|
|Alice, Concurrent ML, Dependent ML|
Standard ML (SML) is a general-purpose, modular, functional programming language with compile-time type checking and type inference. It is popular among compiler writers and programming language researchers, as well as in the development of theorem provers.
SML is a modern descendant of the ML programming language used in the Logic for Computable Functions (LCF) theorem-proving project. It is distinctive among widely used languages in that it has a formal specification, given as typing rules and operational semantics in The Definition of Standard ML (1990, revised and simplified as The Definition of Standard ML (Revised) in 1997).
- 1 Language
- 2 Code examples
- 3 Implementations
- 4 See also
- 5 References
- 6 External links
Standard ML is a functional programming language with some impure features. Programs written in Standard ML consist of expressions to be evaluated, as opposed to statements or commands, although some expressions return a trivial "unit" value and are only evaluated for their side-effects.
fun factorial n = if n = 0 then 1 else n * factorial (n-1)
A Standard ML compiler is required to infer the static type int -> int of this function without user-supplied type annotations. I.e., it has to deduce that n is only used with integer expressions, and must therefore itself be an integer, and that all value-producing expressions within the function return integers.
The same function can be expressed with clausal function definitions where the if-then-else conditional is replaced by a sequence of templates of the factorial function evaluated for specific values, separated by '|', which are tried one by one in the order written until a match is found:
fun factorial 0 = 1 | factorial n = n * factorial (n - 1)
This can be rewritten using a case statement like this:
val rec factorial = fn n => case n of 0 => 1 | n => n * factorial (n - 1)
or as a lambda function:
val rec factorial = fn 0 => 1 | n => n * factorial(n -1)
Here, the keyword
val introduces a binding of an identifier to a value,
fn introduces the definition of an anonymous function, and
case introduces a sequence of patterns and corresponding expressions.
Using a local function, this function can be rewritten in a more efficient tail recursive style.
fun factorial n = let fun lp (0, acc) = acc | lp (m, acc) = lp (m-1, m*acc) in lp (n, 1) end
(The value of a let-expression is that of the expression between in and end.) The encapsulation of an invariant-preserving tail-recursive tight loop with one or more accumulator parameters inside an invariant-free outer function, as seen here, is a common idiom in Standard ML, and appears with great frequency in SML code.
A type synonym is defined with the type keyword. Here is a type synonym for points in the plane, and functions computing the distances between two points, and the area of a triangle with the given corners as per Heron's formula.
type loc = real * real fun dist ((x0, y0), (x1, y1)) = let val dx = x1 - x0 val dy = y1 - y0 in Math.sqrt (dx * dx + dy * dy) end fun heron (a, b, c) = let val ab = dist (a, b) val bc = dist (b, c) val ac = dist (a, c) val perim = ab + bc + ac val s = perim / 2.0 in Math.sqrt (s * (s - ab) * (s - bc) * (s - ac)) end
Algebraic datatypes and pattern matching
Standard ML provides strong support for algebraic datatypes. An ML datatype can be thought of as a disjoint union of tuples (or a "sum of products"). They are easy to define and easy to program with, in large part because of Standard ML's pattern matching as well as most Standard ML implementations' pattern exhaustiveness checking and pattern redundancy checking.
A datatype is defined with the datatype keyword, as in
datatype shape = Circle of loc * real (* center and radius *) | Square of loc * real (* upper-left corner and side length; axis-aligned *) | Triangle of loc * loc * loc (* corners *)
(See above for the definition of loc.) Note: datatypes, not type synonyms, are necessary to define recursive constructors. (This is not at issue in the present example.)
Order matters in pattern matching; patterns that are textually first are tried first. Pattern matching can be syntactically embedded in function definitions as follows:
fun area (Circle (_, r)) = 3.14 * r * r | area (Square (_, s)) = s * s | area (Triangle (a, b, c)) = heron (a, b, c) (* see above *)
Note that subcomponents whose values are not needed in a particular computation are ellided with underscores, or so-called wildcard patterns.
The so-called "clausal form" style function definition, where patterns appear immediately after the function name, is merely syntactic sugar for
fun area shape = case shape of Circle (_, r) => 3.14 * r * r | Square (_, s) => s * s | Triangle (a, b, c) => heron (a, b, c)
Pattern exhaustiveness checking will make sure each case of the datatype has been accounted for, and will produce a warning if not. The following pattern is inexhaustive:
fun center (Circle (c, _)) = c | center (Square ((x, y), s)) = (x + s / 2.0, y + s / 2.0)
There is no pattern for the Triangle case in the center function. The compiler will issue a warning that the pattern is inexhaustive, and if, at runtime, a Triangle is passed to this function, the exception Match will be raised.
The set of clauses in the following function definition is exhaustive and not redundant:
fun hasCorners (Circle _) = false | hasCorners _ = true
If control gets past the first pattern (the Circle), we know the value must be either a Square or a Triangle. In either of those cases, we know the shape has corners, so we can return true without discriminating which case we are in.
The pattern in second clause the following (meaningless) function is redundant:
fun f (Circle ((x, y), r)) = x+y | f (Circle _) = 1.0 | f _ = 0.0
Any value that matches the pattern in the second clause will also match the pattern in the first clause, so the second clause is unreachable. Therefore, this definition as a whole exhibits redundancy, and causes a compile-time warning.
C programmers can use tagged unions, dispatching on tag values, to accomplish what ML accomplishes with datatypes and pattern matching. Nevertheless, while a C program decorated with appropriate checks will be in a sense as robust as the corresponding ML program, those checks will of necessity be dynamic; ML provides a set of static checks that give the programmer a high degree of confidence in the correctness of the program at compile time.
Note that in object-oriented programming languages, such as Java, a disjoint union can be expressed by designing class hierarchies. However, as opposed to class hierarchies, ADTs are closed. This makes ADT extensible in a way that is orthogonal to the extensibility of class hierarchies. Class hierarchies can be extended with new subclasses but no new methods, while ADTs can be extended to provide new behavior for all existing constructors, but do not allow defining new constructors.
Functions can consume functions as arguments:
fun applyToBoth f x y = (f x, f y)
Functions can produce functions as return values:
fun constantFn k = let fun const anything = k in const end
fun constantFn k = (fn anything => k)
Functions can also both consume and produce functions:
fun compose (f, g) = let fun h x = f (g x) in h end
fun compose (f, g) = (fn x => f (g x))
List.map from the basis library is one of the most commonly used higher-order functions in Standard ML:
fun map _ = | map f (x::xs) = f x :: map f xs
(A more efficient implementation of
map would define a tail-recursive inner loop as follows:)
fun map f xs = let fun m (, acc) = List.rev acc | m (x::xs, acc) = m (xs, f x :: acc) in m (xs, ) end
Exceptions are raised with the
raise keyword, and handled with pattern matching
exception Undefined fun max [x] = x | max (x::xs) = let val m = max xs in if x > m then x else m end | max = raise Undefined fun main xs = let val msg = (Int.toString (max xs)) handle Undefined => "empty list...there is no max!" in print (msg ^ "\n") end
The exception system can be exploited to implement non-local exit, an optimization technique suitable for functions like the following.
exception Zero fun listProd ns = let fun p = 1 | p (0::_) = raise Zero | p (h::t) = h * p t in (p ns) handle Zero => 0 end
When the exception
Zero is raised in the 0 case, control leaves the function
p altogether. Consider the alternative: the value 0 would be returned to the most recent awaiting frame, it would be multiplied by the local value of
h, the resulting value (inevitably 0) would be returned in turn to the next awaiting frame, and so on. The raising of the exception allows control to leapfrog directly over the entire chain of frames and avoid the associated computation. It has to be noted that the same optimization could have been obtained by using a tail recursion for this example.
Standard ML has an advanced module system, allowing programs to be decomposed into hierarchically organized structures of logically related type and value declarations. SML modules provide not only namespace control but also abstraction, in the sense that they allow programmers to define abstract data types.
Three main syntactic constructs comprise the SML module system: signatures, structures and functors. A structure is a module; it consists of a collection of types, exceptions, values and structures (called substructures) packaged together into a logical unit. A signature is an interface, usually thought of as a type for a structure: it specifies the names of all the entities provided by the structure as well as the arities of type components, the types of value components, and signatures for substructures. The definitions of type components may or may not be exported; type components whose definitions are hidden are abstract types. Finally, a functor is a function from structures to structures; that is, a functor accepts one or more arguments, which are usually structures of a given signature, and produces a structure as its result. Functors are used to implement generic data structures and algorithms.
For example, the signature for a queue data structure might be:
signature QUEUE = sig type 'a queue exception QueueError val empty : 'a queue val isEmpty : 'a queue -> bool val singleton : 'a -> 'a queue val insert : 'a * 'a queue -> 'a queue val peek : 'a queue -> 'a val remove : 'a queue -> 'a * 'a queue end
This signature describes a module that provides a parameterized type
queue of queues, an exception called
QueueError, and six values (five of which are functions) providing the basic operations on queues. One can now implement the queue data structure by writing a structure with this signature:
structure TwoListQueue :> QUEUE = struct type 'a queue = 'a list * 'a list exception QueueError val empty = (,) fun isEmpty (,) = true | isEmpty _ = false fun singleton a = (, [a]) fun insert (a, (, )) = (, [a]) | insert (a, (ins, outs)) = (a::ins, outs) fun peek (_,) = raise QueueError | peek (ins, a::outs) = a fun remove (_,) = raise QueueError | remove (ins, [a]) = (a, (, rev ins)) | remove (ins, a::outs) = (a, (ins,outs)) end
This definition declares that
TwoListQueue is an implementation of the
QUEUE signature. Furthermore, the opaque ascription (denoted by
:>) states that any type components whose definitions are not provided in the signature (i.e.,
queue) should be treated as abstract, meaning that the definition of a queue as a pair of lists is not visible outside the module. The body of the structure provides bindings for all of the components listed in the signature.
To use a structure, one can access its type and value members using "dot notation". For instance, a queue of strings would have type
string TwoListQueue.queue, the empty queue is
TwoListQueue.empty, and to remove the first element from a queue called
q one would write
functor BFS (structure Q: QUEUE) = (* after Okasaki, ICFP, 2000 *) struct datatype 'a tree = E | T of 'a * 'a tree * 'a tree fun bfsQ (q : 'a tree Q.queue) : 'a list = if Q.isEmpty q then else let val (t, q') = Q.remove q in case t of E => bfsQ q' | T (x, l, r) => let val q'' = Q.insert (r, Q.insert (l, q')) in x :: bfsQ q'' end end fun bfs t = bfsQ (Q.singleton t) end
Please note that inside the
BFS structure, the program has no access to the particular queue representation in play. More concretely, there is no way for the program to, say. select the first list in the two-list queue representation, if that is indeed the representation being used. This data abstraction mechanism makes the breadth-first code truly agnostic to the queue representation choice. This is in general desirable; in the present case, the queue structure can safely maintain any of the various logical invariants on which its correctness depends behind the bulletproof wall of abstraction.
|This section does not cite any sources. (June 2013)|
Snippets of SML code are most easily studied by entering them into a "top-level", also known as a read-eval-print loop or REPL. This is an interactive session that prints the inferred types of resulting or defined expressions. Many SML implementations provide an interactive REPL, including SML/NJ:
$ sml [[Standard ML of New Jersey]] v110.52 [built: Fri Jan 21 16:42:10 2005] -
Code can then be entered at the "-" prompt. For example, to calculate 1+2*3:
- 1 + 2 * 3; val it = 7 : int
The top-level infers the type of the expression to be "int" and gives the result "7".
The following program "hello.sml":
print "Hello world!\n";
can be compiled with MLton:
$ mlton hello.sml
$ ./hello Hello world!
Insertion sort for lists of integers (ascending) is expressed concisely as follows:
fun ins (n, ) = [n] | ins (n, ns as h::t) = if (n<h) then n::ns else h::(ins (n, t)) val insertionSort = List.foldr ins
This can be made polymorphic by abstracting over the ordering operator. Here we use the symbolic name
<< for that operator.
fun ins' << (num, nums) = let fun i (n, ) = [n] | i (n, ns as h::t) = if <<(n,h) then n::ns else h::i(n,t) in i (num, nums) end fun insertionSort' << = List.foldr (ins' <<)
The type of
('a * 'a -> bool) -> ('a list) -> ('a list).
Here, the classic mergesort algorithm is implemented in three functions: split, merge and mergesort.
split is implemented with a local function named
loop, which has two additional parameters. The local function
loop is written in a tail-recursive style; as such it can be compiled efficiently. This function makes use of SML's pattern matching syntax to differentiate between non-empty list (
x::xs) and empty list (
) cases. For stability, the input list
ns is reversed before being passed to
(* Split list into two near-halves, returned as a pair. * The “halves” will either be the same size, * or the first will have one more element than the second. * Runs in O(n) time, where n = |xs|. *) local fun loop (x::y::zs, xs, ys) = loop (zs, x::xs, y::ys) | loop (x::, xs, ys) = (x::xs, ys) | loop (, xs, ys) = (xs, ys) in fun split ns = loop (List.rev ns, , ) end
The local-in-end syntax could be replaced with a let-in-end syntax, yielding the equivalent definition:
fun split ns = let fun loop (x::y::zs, xs, ys) = loop (zs, x::xs, y::ys) | loop (x::, xs, ys) = (x::xs, ys) | loop (, xs, ys) = (xs, ys) in loop (List.rev ns, , ) end
As with split, merge also uses a local function loop for efficiency. The inner
loop is defined in terms of cases: when two non-empty lists are passed, when one non-empty list is passed, and when two empty lists are passed. Note the use of the underscore (
_) as a wildcard pattern.
This function merges two "ascending" lists into one ascending list. Note how the accumulator
out is built "backwards", then reversed with
List.rev before being returned. This is a common technique—build a list backwards, then reverse it before returning it. In SML, lists are represented as imbalanced binary trees, and thus it is efficient to prepend an element to a list, but inefficient to append an element to a list. The extra pass over the list is a linear time operation, so while this technique requires more wall clock time, the asymptotics are not any worse.
(* Merge two ordered lists using the order lt. * Pre: the given lists xs and ys must already be ordered per lt. * Runs in O(n) time, where n = |xs| + |ys|. *) fun merge lt (xs, ys) = let fun loop (out, left as x::xs, right as y::ys) = if lt (x, y) then loop (x::out, xs, right) else loop (y::out, left, ys) | loop (out, x::xs, ) = loop (x::out, xs, ) | loop (out, , y::ys) = loop (y::out, , ys) | loop (out, , ) = List.rev out in loop (, xs, ys) end
The main function.
(* Sort a list in according to the given ordering operation lt. * Runs in O(n log n) time, where n = |xs|. *) fun mergesort lt xs = let val merge' = merge lt fun ms = | ms [x] = [x] | ms xs = let val (left, right) = split xs in merge' (ms left, ms right) end in ms xs end
Also note that the code makes no mention of variable types, with the exception of the :: and syntax which signify lists. This code will sort lists of any type, so long as a consistent ordering function lt can be defined. Using Hindley–Milner type inference, the compiler is capable of inferring the types of all variables, even complicated types such as that of the lt function.
Quicksort can be expressed as follows. This generic quicksort consumes an order operator
fun quicksort << xs = let fun qs = | qs [x] = [x] | qs (p::xs) = let val (less, more) = List.partition (fn x => << (x, p)) xs in qs less @ p :: qs more end in qs xs end
Note the relative ease with which a small expression language is defined and processed.
exception Err datatype ty = IntTy | BoolTy datatype exp = True | False | Int of int | Not of exp | Add of exp * exp | If of exp * exp * exp fun typeOf (True) = BoolTy | typeOf (False) = BoolTy | typeOf (Int _) = IntTy | typeOf (Not e) = if typeOf e = BoolTy then BoolTy else raise Err | typeOf (Add (e1, e2)) = if (typeOf e1 = IntTy) andalso (typeOf e2 = IntTy) then IntTy else raise Err | typeOf (If (e1, e2, e3)) = if typeOf e1 <> BoolTy then raise Err else if typeOf e2 <> typeOf e3 then raise Err else typeOf e2 fun eval (True) = True | eval (False) = False | eval (Int n) = Int n | eval (Not e) = (case eval e of True => False | False => True | _ => raise Fail "type-checking is broken") | eval (Add (e1, e2)) = let val (Int n1) = eval e1 val (Int n2) = eval e2 in Int (n1 + n2) end | eval (If (e1, e2, e3)) = if eval e1 = True then eval e2 else eval e3 fun chkEval e = (ignore (typeOf e); eval e) (* will raise Err on type error *)
Arbitrary-precision factorial function (libraries)
In SML, the IntInf module provides arbitrary-precision integer arithmetic. Moreover, integer literals may be used as arbitrary-precision integers without the programmer having to do anything.
The following program "fact.sml" implements an arbitrary-precision factorial function and prints the factorial of 120:
fun fact n : IntInf.int = if n=0 then 1 else n * fact(n - 1) val () = print (IntInf.toString (fact 120) ^ "\n")
and can be compiled and run with:
$ mlton fact.sml $ ./fact 66895029134491270575881180540903725867527463331380298102956713523016335 57244962989366874165271984981308157637893214090552534408589408121859898 481114389650005964960521256960000000000000000000000000000
Numerical derivative (higher-order functions)
Since SML is a functional programming language, it is easy to create and pass around functions in SML programs. This capability has an enormous number of applications. Calculating the numerical derivative of a function is one such application. The following SML function "d" computes the numerical derivative of a given function "f" at a given point "x":
- fun d delta f x = (f (x + delta) - f (x - delta)) / (2.0 * delta); val d = fn : real -> (real -> real) -> real -> real
The type of the function "d" indicates that it maps a "float" onto another function with the type "(real -> real) -> real -> real". This allows us to partially apply arguments. This functional style is known as currying. In this case, it is useful to partially apply the first argument "delta" to "d", to obtain a more specialised function:
- val d = d 1E~8; val d = fn : (real -> real) -> real -> real
Note that the inferred type indicates that the replacement "d" is expecting a function with the type "real -> real" as its first argument. We can compute a numerical approximation to the derivative of at with:
- d (fn x => x * x * x - x - 1.0) 3.0; val it = 25.9999996644 : real
The correct answer is ; .
The function "d" is called a "higher-order function" because it accepts another function ("f") as an argument.
Curried and higher-order functions can be used to eliminate redundant code. For example, a library may require functions of type
a -> b, but it is more convenient to write functions of type
a * c -> b where there is a fixed relationship between the objects of type
c. A higher order function of type (a * c -> b) -> (a -> b) can factor out this commonality. This is an example of the adapter pattern.
Discrete wavelet transform (pattern matching)
The 1D Haar wavelet transform of an integer-power-of-two-length list of numbers can be implemented very succinctly in SML and is an excellent example of the use of pattern matching over lists, taking pairs of elements ("h1" and "h2") off the front and storing their sums and differences on the lists "s" and "d", respectively:
- fun haar l = let fun aux [s] d = s :: d | aux s d = aux s d | aux (h1::h2::t) s d = aux t (h1+h2 :: s) (h1-h2 :: d) | aux _ _ _ = raise Empty in aux l end; val haar = fn : int list -> int list
- haar [1, 2, 3, 4, ~4, ~3, ~2, ~1]; val it = [0,20,4,4,~1,~1,~1,~1] : int list
Pattern matching is a useful construct that allows complicated transformations to be represented clearly and succinctly. Moreover, SML compilers turn pattern matches into efficient code, resulting in programs that are not only shorter but also faster.
Many SML implementations exist, including:
- MLton is a whole-program optimizing compiler that produces very fast code compared to other ML implementations.
- Poly/ML is a full implementation of Standard ML that produces fast code and supports multicore hardware (via Posix threads); its runtime system performs parallel garbage collection and online sharing of immutable substructures.
- Isabelle/ML integrates parallel Poly/ML into an interactive theorem prover, with a sophisticated IDE (based on jEdit) both for the Isabelle/ML dialect and the proof language. Starting with Isabelle2014, official Standard ML (SML'97) is supported as well.
- Standard ML of New Jersey (abbreviated SML/NJ) is a full compiler, with associated libraries, tools, an interactive shell, and documentation.
- Moscow ML is a light-weight implementation, based on the CAML Light runtime engine. It implements the full SML language, including SML Modules, and much of the SML Basis Library.
- CakeML a read-eval-print loop version of ML with formally verified runtime and translation to assembler
- HaMLet is an SML interpreter that aims to be an accurate and accessible reference implementation of the standard.
- The ML Kit integrates a garbage collector (which can be disabled) and region-based memory management with automatic inference of regions, aiming to support realtime applications. Its implementation is based very closely on the Definition.
- TILT is a full certifying compiler for SML. It uses typed intermediate languages to optimize code and ensure correctness, and can compile to Typed assembly language.
- SML.NET allows compiling to the Microsoft CLR and has extensions for linking with other .NET code.
- SML2c is a batch compiler and compiles only module-level declarations (i.e. signatures, structures, functors) into C. It is based on SML/NJ version 0.67 and shares the front end, and most of its run-time system, but does not support SML/NJ style debugging and profiling. Module-level programs that run on SML/NJ can be compiled by sml2c with no changes.
- The Poplog system implements a version of SML, with POP-11, and optionally Common Lisp, and Prolog, allowing mixed language programming. For all, the implementation language is POP-11, which is compiled incrementally. It also has an integrated Emacs-like editor that communicates with the compiler.
- SML# is an extension of SML providing record polymorphism and C language interoperability. It is a conventional native compiler and its name is not an allusion to running on the .NET framework.
- Alice: an interpreter for Standard ML by Saarland University adding features for lazy evaluation, concurrency (multithreading and distributed computing via remote procedure calls) and constraint programming.
All of these implementations are open-source and freely available. Most are implemented themselves in SML. There are no longer any commercial SML implementations. Harlequin once produced a commercial IDE and compiler for SML called MLWorks. The company is now defunct. MLWorks passed on to Xanalys and was later acquired by Ravenbrook Limited on 2013-04-26 and open sourced.
- Milner, R. (1997). The Definition of Standard ML (Revised). MIT Press. ISBN 0-262-63181-4. Unknown parameter
- Okasaki, Chris (2000). "Breadth-First Numbering: Lessons from a Small Exercise in Algorithm Design". International Conference on Functional Programming 2000. ACM.
- "CakeML". cakeml.org.
- What is SML?
- What is SML '97?
- successor ML (sML) is intended to provide a vehicle for the continued evolution of ML, using Standard ML as a starting point.
- Standard ML language Mads Tofte, Scholarpedia, 4(2):7515. doi:10.4249/scholarpedia.7515
- Univ. of Chicago - SML tutorial (slides)
- Carnegie Mellon Univ. - The Book of SML
- Carnegie Mellon Univ. - SML - Examples
- University of Edinburgh - Programming in Standard ML '97: A Tutorial Introduction (pdf)
- University of Edinburgh - SML '97 - Online Tutorial | <urn:uuid:0380bfd6-ae2c-4a45-acb0-a17b15ded07f> | 2.984375 | 6,893 | Documentation | Software Dev. | 58.733362 | 95,630,156 |
The experiment, outlined in a new paper,* would not only mean more accurate identifications of elements in everything from stars to environmental pollutants but also could put the modern theory of the atom to the most stringent tests yet.
The physicists’ quarry is the Rydberg constant, the quantity that specifies the precise color of light that is emitted when an electron jumps from one energy level to another in an atom. The current value of the Rydberg constant comes from comparing theory and experiment for 23 different kinds of energy jumps in hydrogen and deuterium atoms. Researchers have experimentally measured the frequencies of light emitted by these atomic transitions (energy jumps) to an accuracy of as high as 14 parts per quadrillion (one followed by 15 zeros), but the value of the Rydberg constant is known only to about 6.6 parts in a trillion—500 times less accurate. The main hurdle to a more accurate value comes from uncertainties in the size of the atom’s nucleus, which can alter the electron’s energy levels and therefore modify the frequency of light it emits. Another source of uncertainty comes from the fact that electrons sometimes emit and reabsorb short-lived “virtual photons,” a process that also can slightly change the electron’s energy level.
To beat these problems, NIST physicist Peter Mohr and his colleagues propose engineering so-called hydrogen-like Rydberg atoms—atomic nuclei stripped of all but a single electron in a high-lying energy level far away from the nucleus. In such atoms, the electron is so far away from the nucleus that the latter’s size is negligible, and the electron would accelerate less in its high-flung orbit, reducing the effects of “virtual photons” it emits. These simplifications allow theoretical uncertainties to be as small as tens of parts in a quintillion (one followed by 18 zeros).
NIST researchers Joseph Tan and colleagues hope to implement this approach experimentally in their Electron Beam Ion Trap Facility. The idea would be to strip an atom of all its electrons, cool it and inject a single electron in a high-flying orbit. Then the researchers would use a sensitive measurement device known as a frequency comb to measure the light absorbed by this Rydberg atom. The result could be an ultraprecise frequency measurement that would yield an improved value for the Rydberg constant. Such a measurement would be so sensitive that it could reveal anomalies in quantum electrodynamics, the modern theory of the atom.
Ben Stein | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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A synthesis of current knowledge of the growth, development and functioning of plant canopies.
Discussion of the meaning of canopy structure, interception of solar radiation, exchange processes, nitrogen nutrition, leaf demography, heliotropism, canopy architecture and modelling processes. Covers a wide range of plant community types and geographical locations. SciTech Book Newsu "...useful to agronomists and others interested in agricultural applications of 'canopy' growth and form." Biochemical Systematics and Ecology "...one of a small number of works that define the starting point for the plant biology of the next decade...To the extent that the book's purpose is to identify the range and introduce some of the research activities at the canopy level, it is very successful. The book is interesting, accessible and timely." American Scientist
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The LiteBIRD Satellite Mission: Sub-Kelvin Instrument
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Inflation is the leading theory of the first instant of the universe. Inflation, which postulates that the universe underwent a period of rapid expansion an instant after its birth, provides convincing explanation for cosmological observations. Recent advancements in detector technology have opened opportunities to explore primordial gravitational waves generated by the inflation through “B-mode” (divergent-free) polarization pattern embedded in the cosmic microwave background anisotropies. If detected, these signals would provide strong evidence for inflation, point to the correct model for inflation, and open a window to physics at ultra-high energies. LiteBIRD is a satellite mission with a goal of detecting degree-and-larger-angular-scale B-mode polarization. LiteBIRD will observe at the second Lagrange point with a 400 mm diameter telescope and 2622 detectors. It will survey the entire sky with 15 frequency bands from 40 to 400 GHz to measure and subtract foregrounds. The US LiteBIRD team is proposing to deliver sub-Kelvin instruments that include detectors and readout electronics. A lenslet-coupled sinuous antenna array will cover low-frequency bands (40–235 GHz) with four frequency arrangements of trichroic pixels. An orthomode-transducer-coupled corrugated horn array will cover high-frequency bands (280–402 GHz) with three types of single frequency detectors. The detectors will be made with transition edge sensor (TES) bolometers cooled to a 100 milli-Kelvin base temperature by an adiabatic demagnetization refrigerator. The TES bolometers will be read out using digital frequency multiplexing with Superconducting QUantum Interference Device (SQUID) amplifiers. Up to 78 bolometers will be multiplexed with a single SQUID amplifier. We report on the sub-Kelvin instrument design and ongoing developments for the LiteBIRD mission.
KeywordsCosmic microwave background Satellite Inflation Polarization B-mode
Development for the sub-Kelvin instrument was supported by the NASA Mission of Opportunity Phase A effort.
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- 11.A. Catalano, P. Ade, Y. Atik, A. Benoit, E. Bréele, J.J. Bock, P. Camus, M. Chabot, M. Charra, B.P. Crill, N. Coron, A. Coulais, F.-X. Désert, L. Fauvet, Y. Giraud-Héraud, O. Guillaudin, W. Holmes, W.C. Jones, J.-M. Lamarre, J. Macías-Pérez, M. Martinez, A. Miniussi, A. Monfardini, F. Pajot, G. Patanchon, A. Pelissier, M. Piat, J.-L. Puget, C. Renault, C. Rosset, D. Santos, A. Sauvé, L.D. Spencer, R. Sudiwala, Impact of particles on the Planck HFI detectors: Ground-based measurements and physical interpretation. AAP 569, A88 (2014)CrossRefGoogle Scholar | <urn:uuid:92c9668f-8ae6-4a83-a849-ec001165871c> | 2.65625 | 2,262 | Academic Writing | Science & Tech. | 89.493886 | 95,630,171 |
In this program we are going to tell you how you can write a simple "Hello World" word in a pdf, rtf and html file irrespective of the fact whether it exists or not.
To make a program over this, firstly we need to import some packages. Remember to make this program the first and foremost thing to remember is to place the iText.jar in WEB-INF/lib of your web application. The packages we were talking about are java.io.* for input output, com.lowagie.text.pdf.*, and com.lowagie.text.*. These two package will help us to make and use pdf file in our program. The package com.lowagie.text.html.HtmlWriter will help you to write the content in Html file, The package com.lowagie.text.pdf.PdfWriter helps to write the content in the pdf file and com.lowagie.text.rtf.RtfWriter2 helps you to write in rtf format.
Now create a file named differentWritersMultiple. Remember the name of the file should be such that the reader can understand what the program is going to perform. Inside the class declare a main method inside which we are going to write the logic of our program.
Firstly make a object of class Document. The Document describes a document's page size, margins, and other important attributes. It works as a container for a document's chapters, sections, images, paragraphs, and other content.
Now create a document writer that writes the equivalent syntax for a document's content to a specific OutputStream. PdfWriter.getInstance() creates a PDF document writer that writes PDF syntax to concerned file by a FileOutputStream. In our example we have created a three different writers that listen to the document. The different writers are for pdf, html and for rtf. If the pdf file doesn't exist then it will create a pdf file by that name.
Now open the document by document.open(). After that add the paragraph to the document. For that create a Paragraph that houses a paragraph of text, tells the PDF document writer to ensure that the Paragraph's text is justified on both sides and adds the Paragraph to the previously created Document. Inside the constructor of Paragraph we have passed one String "Hello World" . Now we need to make the references, we add the references, but only to the HTML page. At last closes the document by using the document.close(). The closing of the document is important because it flushes and closes the OutputStream instance.
The code of the program is given below:
The output of the program is given below: | <urn:uuid:8bd32f96-8001-4854-b151-04d6ce71e963> | 3.3125 | 557 | Documentation | Software Dev. | 66.052654 | 95,630,176 |
The state in which the element is stable
at a chosen standard-state pressure and for a given temperature.
PAC, 1982, 54, 1239
(Notation for states and processes, significance of the word standard in chemical
thermodynamics, and remarks on commonly tabulated forms of thermodynamic functions)
on page 1249
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. https://doi.org/10.1351/goldbook | <urn:uuid:63b23229-5eef-4e83-9260-6edff97739fc> | 2.96875 | 186 | Knowledge Article | Science & Tech. | 69.894361 | 95,630,185 |
16°C / 61°F
The measurements for the water temperature in Førde, Sogn og Fjordane are provided by the daily satellite readings provided by the NOAA. The temperatures given are the sea surface temperature (SST) which is most relevant to recreational users.
The graph below shows the range of monthly Førde water temperature derived from many years of historical sea surface temperature data.
These average ocean temperatures for Førde are calculated from several years of archived data.
Whilst sea temperatures for Førde are as accurate as current data allows, there may be slight local and regional variations depending on conditions. Time of day and wind direction may have a temporary local effect as can water flows from neraby rivers. | <urn:uuid:37e656ce-6527-4bb1-9d9f-d35e38baa6a8> | 2.59375 | 156 | Knowledge Article | Science & Tech. | 26.746183 | 95,630,234 |
Fig. 3 is showing the Jablonski diagram (Jablonski, 1933), a schematic of the transition of electronic state of a molecule during the fluorescence phenomenon. The left axis shows increasing energy, where a typical fluorescent molecule has an absorbance spectrum. This spectrum shows the energy or wavelengths, where the molecule will absorb light.
If the incident light is at a wavelength where the molecule will absorb the photon, the molecule is then excited from the electronic ground state to a higher excited state, denoted S2 here.
The electrons then go through internal conversion, affected by vibrational relaxation and heat loss to the environment. A photon is then emitted from the lowest lying singlet excited state in the form of fluorescence.
In conventional fluorescence, photons are emitted at higher wavelengths than the photons which are absorbed. This diagram is extremely important to understand fluorescence. When measuring a fluorescence spectrum, one is typically looking at the intensity at which a molecule emits, the wavelength or energy at which it emits, and also the time which the molecule spends in the excited state. This is the fluorescence lifetime, explained further in detail in coming sections.
Any number of things can affect these observables, including energy transfer to and from other molecules, quenching by other molecules, temperature, pH, local polarity, aggregation or binding. Understanding the mechanisms of these interactions can give one insight into what is being observed with a change in fluorescence spectra or lifetime.
There are two non-radiative deactivation processes that compete with fluorescence: internal conversion from the lowest singlet excited to the ground state and intersystem crossing from the excited singlet state to the triplet state. This last process leads to the phenomenon called phosphorescence, explained in further detail later on.
In simple terms, fluorescence lifetime of a molecule can be thought of as the average length of time it spends in the excited state. This depends on the type of molecule and its local environment. Typically the excited state decays in an exponential manner, as indicated in the equation below. The use of fluorescence lifetime has its advantages over that of an intensity measurement, as it is an “absolute” measurement, rather than the “relative” steady state measurement (which gives a time averaged signal).
I(t) = I0 exp(-t/τ)
τ is the fluorescence lifetime or the time for the intensity to decay to 1/e of its initial value.
If more than one excited state is present, sometimes because the sample under study contains a mixture of fluorescing molecules, and there are different local environments or a molecule undergoes a transformation giving rise to different excited state species, the decay is expected to be more complex. There can be one exponential decay per excited state present. This can be represented by a sum of exponentials (see below), where α (the pre-exponential factor) is indicative of the relative concentration of each t decay to the observed overall decay.
In order to compare measurements, it is often useful to normalize the pre-exponential factors in some way. If a comparison of the concentration of each fluorescing species is required, then the normalized α may be used. If a comparison of the contribution to steady state spectrum (overall fluorescence emission) is needed, then the fractional or relative amplitude (in %) can be used. The latter is the pre-exponential factor weighted by the lifetime.
At times, it can be just as acceptable to represent a complex decay by an average lifetime. However, it should be noted that this is best done by actually correctly modelling the complex decay, rather than just attempting to fit a single exponential decay to it. In most cases, the use of the amplitude average lifetime is appropriate, however, when considering quenching experiments, it is more correct to employ the intensity average fluorescence lifetime. There are published works going into the details of the relative merits of these averages. (Lakowicz, 2006) (Berezin, 2010)
Phosphorescence is a process where the photon is emitted, not from a singlet excited state, but from a forbidden triplet state. The time scale of fluorescence emission is generally in the picosecond to nanosecond range, while phosphorescence typically lasts for microseconds, milliseconds, or even longer…minutes or hours. A pulsed source is typically used, such as a flash lamp or LED to measure phosphorescence spectra and decays on these longer time scales. Phosphorescence measurements use a longer lived pulsed source, such as a xenon flash lamp. The timing of the flashing lamp can be used to measure spectra at different phosphorescence lifetimes.
Phosphorescence measurements use a longer lived pulsed source, such as a xenon flash lamp. The timing of the flashing lamp can be used to measure spectra at different phosphorescence lifetimes. | <urn:uuid:4ebb6bdb-7d7b-41c3-a452-b0af1083e3f1> | 3.625 | 1,007 | Knowledge Article | Science & Tech. | 22.345106 | 95,630,238 |
The system will be unavailable due to maintenance on Thursday July 19 from 7:00-8:30 am ET.
Toxicity of Copper to Mercenaria mercenaria (Hard Clam)
LaBreche, Timothy Merrick Clark
MetadataShow full item record
Toxicity of copper to larval Mercenaria mercenaria was evaluated with static non-renewal and continuous renewal methods that permitted daily observation of mortality, activity, development, and metamorphosis without subsampling. Clam larvae, 100 - 150 microns, were held for up to two weeks in small, 30 mm, sealed petri plates during static assays with excellent survival of control organisms, low evaporative losses, and relatively low between replicate variability. An eight day LC50 of 12 micrograms / liter for six day old organisms was determined as well as EC50s (active swimming). EC50s at 24 hours were as much as much as seven times lower than LC50s after 24 hours of exposure. Flow - through assays were conducted with a modified petri dish design. Two sections from opposing sides of a 30 mm petri dish were removed and covered with 35 micron polyester screening. This dish (organism dish) was placed in an outer catch dish that captured the effluent toxin as it passed through the screening and routed it to a catch bottle for water quality analysis. The toxicant feed line entered through the catch dish cover and slowly dripped toxin into the organism dish. Water quality in the flow - through assay remained excellent. Survival of control organisms in the flow - through assay was lower than in static assays, but metamorphosis was not delayed as had been observed in static assays. Data variability was low enough that statistical distinctions were made between the effects of copper on metamorphosis. A non-standard "M" shaped survival response was observed in all assays. The responses generating the "M" shaped response in the static petri assay were statistically different from each other. Activity, as judged by swimming, in organisms was not observed to follow the "M" shaped pattern. Instead, it decreased exponentially with increasing copper concentrations. Static experiments with unfed clams, observations of activity, and data from experiments in copper accumulation by algae led to a theory relating the unusual dose response to food consumption and its relationship to the effective dose of copper to which the larval clams were exposed.
- Masters Theses | <urn:uuid:b94466a5-cab7-49e5-9693-f4f320174823> | 2.6875 | 497 | Academic Writing | Science & Tech. | 31.628081 | 95,630,243 |
Astronomers discover ‘emerald-cut’ galaxy
An international team of astronomers has discovered a rare square galaxy with a striking resemblance to an emerald cut diamond.
The astronomers – from Australia, Germany, Switzerland and Finland – discovered the rectangular‑shaped galaxy within a group of 250 galaxies some 70 million light years away.
“In the Universe around us, most galaxies exist in one of three forms: spheroidal, disc-like, or lumpy and irregular in appearance,” said Associate Professor Alister Graham from Swinburne University of Technology
He said the rare rectangular-shaped galaxy was a very unusual object. “It’s one of those things that just makes you smile because it shouldn’t exist, or rather you don’t expect it to exist.
“It’s a little like the precarious Leaning Tower of Pisa or the discovery of some exotic new species which at first glance appears to defy the laws of nature.”
The unusually shaped galaxy was detected in a wide field-of-view image taken with the Japanese Subaru Telescope for an unrelated program by Swinburne astrophysicist Dr Lee Spitler.
The astronomers suspect it is unlikely that this galaxy is shaped like a cube. Instead, they believe that it may resemble an inflated disc seen side on, like a short cylinder.
Support for this scenario comes from observations with the giant Keck Telescope in Hawaii, which revealed a rapidly spinning, thin disc with a side‑on orientation lurking at the centre of the galaxy. The outermost measured edge of this galactic disc is rotating at a speed in excess of 100,000 kilometres per hour.
“One possibility is that the galaxy may have formed out of the collision of two spiral galaxies,” said Swinburne’s Professor Duncan Forbes, co‑author of the research.
“While the pre-existing stars from the initial galaxies were strewn to large orbits creating the emerald cut shape, the gas sank to the mid‑plane where it condensed to form new stars and the disc that we have observed.”
Despite its apparent uniqueness, partly due to its chance orientation, the astronomers have managed to glean useful information for modelling other galaxies.
While the outer boxy shape is somewhat reminiscent of galaxy merger simulations which don’t involve the production of new stars, the disc-like structure is comparable with merger simulations involving star formation.
“This highlights the importance of combining lessons learned from both types of past simulation for better understanding galaxy evolution in the future,” said Associate Professor Graham.
“One of the reasons this emerald cut galaxy was hard to find is due to its dwarf-like status: it has 50 times less stars than our own Milky Way galaxy, plus its distance from us is equivalent to that spanned by 700 Milky Way galaxies placed end-to-end.
“Curiously, if the orientation was just right, when our own disc-shaped galaxy collides with the disc-shaped Andromeda galaxy about three billion years from now we may find ourselves the inhabitants of a square looking galaxy.”
The results will be published in The Astrophysical Journal. http://arxiv.org/pdf/1203.3608v1.pdf | <urn:uuid:5869a6d2-f9e3-4df5-8216-fd036e482e34> | 3.359375 | 681 | News Article | Science & Tech. | 32.620227 | 95,630,255 |
Theory of Special Relativity
by Nadia L. Zakamska
Publisher: arXiv 2015
Number of pages: 98
The main purpose of these notes is to introduce 4-vectors and the matrix notation and to demonstrate their use in solving standard problems in Special Relativity. The pre-requisites for the class are calculus-based Classical Mechanics and Electricity and Magnetism, and Linear Algebra is highly recommended.
Home page url
Download or read it online for free here:
by J D Cresser - Macquarie University
Special relativity lecture notes. From the table of contents: Introduction: What is Relativity?; Frames of Reference; Newtonian Relativity; Einsteinian Relativity;Geometry of Flat Spacetime; Electrodynamics in Special Relativity.
by H. B. Tilton, F. Smarandache - Pima Community College Press
The premise of this book is that the effects of the special theory of relativity are a kinematical perspective rather than being real; but 'reality' is a slippery concept, and it is expected that the reader will keep that in mind.
by David Tong - University of Cambridge
This is an introductory course on Newtonian mechanics and special relativity given to first year undergraduates. Topics: Forces; Dimensional Analysis; Systems of Particles; Central Forces; Rigid Bodies; Non-Inertial Frames; Special Relativity.
by Len Zane - University of Nevada, Las Vegas
The space and time introduced by Albert Einstein is explained by examining a series of simple thought or 'gedanken' experiments. The development makes extensive use of spacetime diagrams to help readers appreciate the full extent of these changes. | <urn:uuid:bc2e46ba-172f-45f1-bd18-771febac409e> | 3.203125 | 351 | Content Listing | Science & Tech. | 19.669352 | 95,630,266 |
why do we need carbon dioxide in the atmosphere
Carbon dioxide is a colorless and non-flammable gas at normal temperature and pressure. Although
than nitrogen and oxygen in, carbon dioxide is an important constituent of our planet's air. A molecule of carbon dioxide (CO ) is made up of one carbon atom and two oxygen atoms. Carbon dioxide is an important greenhouse gas that helps to trap heat in our atmosphere. Without it, our planet would be inhospitably cold. However, a gradual increase in CO concentrations in Earth's atmosphere is helping to drive global warming, threatening to disrupt our planet's climate as average global temperatures gradually rise. Carbon dioxide is the fourth most abundant component of dry air. It has a (parts per million by volume) in Earth's atmosphere. Scientists estimate that before human industrial activity, CO concentration was around 270 ppmv. Carbon dioxide levels in our atmosphere have thus risen about 40% since the onset of human industrialization, and are expected to play a troubling role in raising global temperature. Atmospheric carbon dioxide concentrations have varied substantially in the pre-human history of our planet, and have had profound impacts on global temperatures in the past. Carbon dioxide plays a key role in Earth's, the set of processes that cycle carbon in many forms throughout our environment.
Volcanic outgassing and wildfires are two significant natural sources of CO in Earth's atmosphere. Respiration, the process by which organisms liberate energy from food, emits carbon dioxide. When you exhale, it is carbon dioxide (amongst other gases) that you breathe out. Combustion, whether in the guise of wildfires, as a result of slash-and-burn agricultural practices, or in internal combustion engines, produces carbon dioxide. Photosynthesis, the biochemical process by which plants and some microbes create food, uses up carbon dioxide. Photosynthetic organisms combine CO O) to produce carbohydrates (such as sugars) and emit oxygen as a by-product. Places such as forests and areas of the ocean that support photosynthetic microbes therefore act as massive carbon "sinks", removing carbon dioxide from the atmosphere via photosynthesis. Earth's early atmosphere had much higher CO levels and almost no oxygen; the rise of photosynthetic organisms led to an increase in oxygen which enabled the development of oxygen-breathing creatures such as us! , although incomplete combustion due to limited oxygen supply or an excess of carbon can also produce carbon monoxide (CO).
Carbon monoxide, a dangerous pollutant, eventually oxidizes to carbon dioxide. are used to inflate bicycle tires and life jackets and to power paintball guns. The "fizz" in soda pop is supplied by carbon dioxide. Carbon dioxide is also released by yeast during fermentation, giving beer its head and making champagne bubbly. Because it is not flammable, CO is used in some fire extinguishers. Carbon dioxide forms a weak acid, called carbonic acid (H ), when dissolved in water. Carbon dioxide is the most abundant gas in the atmospheres of Mars and Venus. Solid, frozen carbon dioxide is called "dry ice". The polar ice caps of Mars are a mixture of normal water ice and dry ice. Liquid CO only forms at pressures higher than about 5 times the atmospheric pressure on Earth at sea level, so in many situations dry ice does not melt into a liquid form. Instead, it goes directly from a solid state to a gaseous state in a process called sublimation. The Earths early atmosphere is believed to have been mainly carbon dioxide with little or no oxygen gas. The Earths atmosphere today contains around 21 percent oxygen and about 0. 04 percent carbon dioxide.
So how did the proportion of carbon dioxide in the atmosphere go down, and the proportion of oxygen go up? photosynthesis The chemical change that occurs in the leaves of green plants. It uses light energy to convert carbon dioxide and water into glucose. Oxygen is produced as a by-product of photosynthesis. This process uses carbon dioxide from the atmosphere (with water and sunlight) to produce oxygen (and glucose). The appearance of plants and algae caused the production of oxygen, which is why the proportion of oxygen went up. Photosynthesis by plants and algae used carbon dioxide from the atmosphere, but this is not the only reason why the proportion of carbon dioxide went down. These processes also absorb carbon dioxide from the atmosphere: Today, the burning of fossil fuels (coal and oil) is adding carbon dioxide to the atmosphere faster than it can be removed. This means that the level of carbon dioxide in the atmosphere is increasing, contributing to global warming. It also means that the oceans are becoming more acidic as they dissolve increasing amounts of carbon dioxide. This has an impact on the marine environment, for example making the shells of sea creatures thinner than normal. Now try a.
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why does carbon dioxide cause global warming
why do we need the carbon cycle
why do we need carbon in our body
why do we need carbon dioxide in the atmosphere
why do we burn fuels in wales
why was there no oxygen in the early atmosphere
why do we need to recycle paper | <urn:uuid:7739cd3d-f5e4-4cb4-9ceb-4575c5f829ae> | 3.75 | 1,041 | Spam / Ads | Science & Tech. | 35.998354 | 95,630,316 |
In celebration of this International Year of Astronomy, NASA is releasing images of the galactic center region as seen by its Great Observatories to more than 150 planetariums, museums, nature centers, libraries, and schools across the country.
The sites will unveil a giant, 6-foot-by-3-foot print of the bustling hub of our galaxy that combines a near-infrared view from the Hubble Space Telescope, an infrared view from the Spitzer Space Telescope, and an X-ray view from the Chandra X-ray Observatory into one multiwavelength picture. Experts from all three observatories carefully assembled the final image from large mosaic photo surveys taken by each telescope. This composite image provides one of the most detailed views ever of our galaxy's mysterious core.
Participating institutions also will display a matched trio of Hubble, Spitzer, and Chandra images of the Milky Way's center on a second large panel measuring 3 feet by 4 feet. Each image shows the telescope's different wavelength view of the galactic center region, illustrating not only the unique science each observatory conducts, but also how far astronomy has come since Galileo.
The composite image features the spectacle of stellar evolution: from vibrant regions of star birth, to young hot stars, to old cool stars, to seething remnants of stellar death called black holes. This activity occurs against a fiery backdrop in the crowded, hostile environment of the galaxy's core, the center of which is dominated by a supermassive black hole nearly four million times more massive than our Sun. Permeating the region is a diffuse blue haze of X-ray light from gas that has been heated to millions of degrees by outflows from the supermassive black hole as well as by winds from massive stars and by stellar explosions. Infrared light reveals more than a hundred thousand stars along with glowing dust clouds that create complex structures including compact globules, long filaments, and finger-like "pillars of creation," where newborn stars are just beginning to break out of their dark, dusty cocoons.
The unveilings will take place at 152 institutions nationwide, reaching both big cities and small towns. Each institution will conduct an unveiling celebration involving the public, schools, and local media.
The Astrophysics Division of NASA's Science Mission Directorate supports the International Year of Astronomy Great Observatories image unveiling. The project is a collaboration among the Space Telescope Science Institute in Baltimore, Md., the Spitzer Science Center in Pasadena, Calif., and the Chandra X-ray Center in Cambridge, Mass.
Images of the Milky Way galactic center region and a list of places exhibiting these images can be found at:http://hubblesite.org/news/2009/28
Donna Weaver | Newswise Science News
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:1236cc9b-d4fd-4b1f-b952-dd800fae3c45> | 3.828125 | 1,198 | Content Listing | Science & Tech. | 38.165803 | 95,630,338 |
While you can’t set your watch to El Niño or La Niña because it occurs irregularly and sometimes with little warning, when one does emerge it is strongly linked to the calendar month. Typically, events peak during the Northern Hemisphere winter and then weaken or disappear during the spring or summer. In part because ENSO is transitioning, the spring is a difficult time to predict whether the upcoming winter will be El Niño, La Niña, or neutral conditions. This has been called the spring predictability barrier and like most barriers it presents additional challenges to get beyond. Currently, there is a hint of a forecast of a future El Niño but the barrier makes it difficult to be too confident in the predictions.
That makes this a nice time to review why we are able to predict ENSO at all and what aspects are particularly challenging to predict. Unlike weather prediction, where we rarely have to account for changes in the ocean, in ENSO prediction we have to forecast both the slower, more predictable changes in the tropical Pacific Ocean and the faster, less predictable movements of the atmosphere above it. At the risk of spoiling my punch line, during the spring, the starting conditions of the ocean provide less guidance than at other times of year and they are much less helpful for forecasting El Niño events than La Niña events.
Predicting La Niña: Cool down the Ocean
While the focus is often on El Niño, research has suggested that it’s sibling, La Niña, is more predictable than El Niño. To understand this, we turn to one theoretical basis for ENSO, the recharge oscillator. The recharge oscillator says warmer sea surface temperatures (SST) in the eastern Pacific Ocean along the equator weaken the winds and cause poleward movement of warm ocean water. This effect can be seen from the surface down to ~1000 feet below the surface of the ocean. As warmer ocean waters shift away from the equator, cooler water upwells from the deeper ocean, creating a deficit of Warm Water Volume on the equator and can trigger a La Niña event. Arguably, we saw this happen over the last year as we transitioned from a mammoth El Niño event to the weak La Niña conditions of the past several months.
Previous research indicates warm water volume at the equator precede SSTs by 6-9 months. From this one might think that warm water volume should be as good of a sign in predicting El Niño as La Niña. But the figure below tells us a different story. The horizontal x-axis shows that negative values of springtime warm water volume (numbers less than zero) are often related to La Niña-levels of cooling (blue dots) in the Niño-3.4 SST region, which is shown on the vertical y-axis. However, the opposite situation is not as true: positive anomalies in warm water volume do not confidently result in an El Niño event (red dots).
The Warm Water Volume anomaly during February-April compared against Niño-3.4 sea surface temperature (SST) during the following November-January. Large negative values of Warm Water Volume anomalies almost always lead to a La Niña event. However, large positive Warm Water Volume anomalies do not lead to El Niño events. For SST data, OISST is used. Warm Water Volume comes from the PMEL analysis (http://www.pmel.noaa.gov/elnino/upper-ocean-heat-content-and-enso). Figure provided by Aaron Levine and modified by Climate.gov.
Predicting El Niño: Warm up the Ocean and Turn On the Noise
So, what makes warm water volume a worse indicator for El Niño events than La Niña events? Simply put, plain old weather over the equatorial Pacific Ocean greatly complicates the picture.
To understand how the weather impacts ENSO, let’s start by thinking about what happens when we blow across a pan of hot water. First, the water cools where we are blowing. Second, the water stacks up on the side of the pan opposite of where we are blowing.
Now to apply this to the tropical Pacific Ocean, where the winds normally blow from east to west, which piles up warm water in the western Pacific (see normal/neutral conditions of the Walker circulation here). Prior to the possible onset of El Niño, we want to see whether the normal winds weaken—a westerly anomaly—and not all at once, but in a series of successive pulses. If strong enough, these Westerly Wind Bursts can simultaneously cool the waters in the extreme western Pacific and allow the warm waters in the western Pacific to slide east. The increase in warm water volume that accompanies these westerly wind bursts can increase the potential for, but not guarantee, an El Niño event.
In fact, expansion of the warm surface waters to the eastern Pacific can also create conditions where more westerly wind bursts will occur! A westerly wind burst makes a second one more likely to occur than the original one (scientists call this “state-dependent noise forcing,” a term that would make you the most popular guest at your next dinner party (4)). This Weather Noise (a measure of winds- for more details see the Methodology section below) results in a larger range of possible outcomes that depends on what happens during the spring and summer months. For example, the ENSO evolution in spring and summer of 2014 was very different from that of 2015 despite very similar starting conditions in the ocean.
Compare the similarities between subsurface (top 300 meters of the ocean) warm water volume in spring 2014 (left) and 2015 (right). Despite the similarities, 2014’s impressive warm anomaly failed to evolve into El Niño, while 2015’s slightly smaller anomaly did. NOAA Climate.gov images based on Climate Prediction Center data. large versions 2014 | 2015
The figure below shows that the influence of weather noise over the March-October time period is very important to the development of El Niño events (red dots). In particular, notice how the red dots cluster on the positive side of the weather noise. This means one needs to see more westerly winds in order to obtain El Niño during the upcoming winter. If there are more easterly winds during March-October (negative values of weather noise), then El Niño does not historically develop regardless of whether there is a deep pool of warm water beneath the surface. On the other hand, the La Niña events (blue dots) occur as often with positive weather noise as negative weather noise.
The Weather Noise forcing from March-October compared against Niño-3.4 sea surface temperature (SST) during the following November-January. The weather noise forcing is an important part of El Niño events, but it is not that important of a component for any other year. The weather noise is calculated from GODAS zonal wind stress using the formula for τR from Levine and Jin 2017. Figure provided by Aaron Levine and modified by Climate.gov.
So, the existence of a large volume of warm water below the surface in the spring isn’t, by itself, a reliable predictor the El Niño will develop because the atmosphere has to help out by relaxing the prevailing winds; and when or if those westerly wind bursts will happen isn’t predictable months in advance.
But why isn’t the same true for La Niña? To a large extent, that takes us back to the recharge oscillator theory mentioned above (and that Michelle blogged about before). According to that theory, as warm surface water from a decaying El Niño drains north and south away from the equator cold water from deeper in the ocean wells up to replace it. These siphoning currents—outflow followed by upwelling—create a strong momentum toward La Niña that is hard to interrupt. That momentum makes weather noise less significant, and it makes deficits of warm water volume in the spring a more reliable predictor that La Niña will develop.
All of that is great, but what does it say about the upcoming winter?
Some model predictions indicate an El Niño event may happen this coming winter. Let’s evaluate these simple ideas in light of that prediction. Currently, the warm water volume anomaly is nearly zero and the SST anomaly is increasing (becoming less negative). With spring time warm water volume anomalies near zero, we can more confidently state there is a smaller likelihood of a La Niña event happening. But, to be even more confident in a possible El Niño, we need to watch carefully what happens with the weather over the tropical Pacific during the spring and even into the summer. The upcoming months will be telling.
What we covered here is a simple framework, but these ideas help reinforce and give a physical basis for what the more complex seasonal climate forecast models are telling us. It is always comforting when the forecasts fit well with our understanding of ENSO predictability. And if (and when!) they don’t align, we see that as an opportunity to better our understanding of ENSO and improve our prediction models.
For more on references and methodology, check out Climate.gov.
This is a guest post by Dr. Aaron Levine who is a National Research Council postdoctoral associate at the NOAA Pacific Marine Environmental Laboratory. His research is on ENSO dynamics and predictability, and focuses on how changes in weather (or what is often referred to as “noise” in climate studies) influence the evolution of ENSO.
Lead reviewer: Michelle L’Heureux, NOAA CPC
Not only did Washington DC set a rain record on Tuesday, it got almost all of this rain (2.63") in a single hour.… https://t.co/dXgLwra54r3 hours ago by WeatherNation
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posted by John Berkhamp
The "random" numbers produced by computers aren't purely random. They are actually pseudo-random, meaning that they are produced by mathematical formulas that simulate randomness.The linear congruential generator takes a seed X0 and generates subsequent pseudo-random numbers using the formula:
Xn+1=(aXn+c) mod m
X1 is the first pseudo-random number generated, X2 is the second, and so on. Let R be the 2000th pseudo-random number generated by the linear congruential generator when X0=42, a=25, c=31, and m=2^20. What are the last three digits of R? | <urn:uuid:4beadd65-7dc7-4c3c-9cea-29d3a9f6f420> | 3.46875 | 146 | Q&A Forum | Science & Tech. | 58.175564 | 95,630,357 |
Join Barron Stone for an in-depth discussion in this video Solution overview, part of Code Clinic: Python (2014).
In this video, I'll give you a high-level overview of my solution to the Code Clinic challenge of retrieving and analyzing weather statistics from Lake Pend Oreille. I'll describe the approach I took to complete the challenge. And then, in the following videos, I'll walk you step by step through the code so you can see exactly how I did it. The solution I've created is written only using packages and modules that are included with the standard Python distribution. In these videos, I'll show you how I used the urllib package to access the Navy's website to retrieve historical data for Lake Pend Oreille.
I use the sqlite3 module to create a database to store a local copy of the retrieved data. I used the new statistics module, which was introduced as the standard module in Python 3.4 to calculate the mean and median values for a range of dates. And finally, I use the tkinter package to build a customized graphical user interface for the application. From the user's perspective, it's a fairly simple program that prompts them to enter a start and end date, and then displays the mean and median values across that range of dates for the wind speed, air temperature and barometric pressure.
While this may look simple at first, there's actually quite a bit going on in the background to provide the user with the result as fast as possible. The main bottleneck for this problem is the time it takes to retrieve the weather data from the Internet. The data is stored in text files on the Navy's website, with individual files for every day, for every type of gathered weather statistic. This means if I need to get wind speed, air temperature and barometric pressure for a single day, I have to download three separate files.
To get the data for two days is six files, three days is nine, and so on. It quickly adds up to a lot of time-consuming web access calls. There are a couple of different approaches that I could have taken to retrieve the weather data for a user’s request. The simplest would be to access the Navy’s website to download all of the necessary data every time the user submits a request. I call this the on-demand solution. As I'm sure you can imagine, this would take a very long time to complete if the user requested even a moderately large range of dates.
On the far other side of the spectrum, I could have created a local database to cache all of the existing weather data for Lake Pond Oreille on the user's machine. The database could be configured to update itself at regular intervals, so that it's always current, and when the user submits a request, the program can just access the fast local cache of data, rather than having to take the time to download it from the internet. One downside of this approach is that the database will require a rather long initial setup period because it will need to download and store all of the historical weather data before the user could even submit their first request.
I did some testing with this method and it took a little over 35 to download and fully populate the local database, which ended up being just under 50 megabytes in size. That was longer than I wanted to wait to use the program, so I decided against this approach. For my solution to the problem, I decided to take an on-demand with caching approach that lies somewhere in the middle. My solution code is divided up into three Python modules. The first module, called lpoApp, is the main module for the program. It creates the graphical user interface for the user to input their start and end dates.
When the user submits a request, it passes those dates to the second module, called lpoDB, to retrieve the weather data for that date range. As the name suggests, the lpoDB module creates and manages a local database to store all of the weather data that's been downloaded. It contains the logic to determine if a specific date has been previously requested and therefore cached in the database or if it's the first time for that date to be requested. First time requests will need to be downloaded from the Internet, in which case, it uses the third module, called IpoWeb, to access the Navy's website to download the data.
That data is returned to the IpoDB module, where it's cached locally in the database, and then all of the data for the requested date range is sent up to the lpoApp module. There, the mean and median values are calculated for the different weather measurements and the results are displayed on the GUI. This on-demand with caching approach only downloads data as needed to fulfill user requests and it caches the data locally to be used quickly to field future requests. In the following videos, I'll walk you through each of these modules individually so you can see how I built the GUI, managed the database, and accessed the Web, as well as learn a few Python tips and tricks along the way.
Barron introduce challenges and provides an overview of his solutions in Python. Challenges include topics such as statistical analysis, searching directories for images, and accessing peripheral devices.
Visit other courses in the series to see how to solve the exact same challenges in languages like C#, C++, Java, PHP, and Ruby.
Skill Level Intermediate
Q: Why can't I access the Lake Pend Orielle site (http://lpo.dt.navy.mil)?
A: The Lake Pend Orielle site is not accessible in some geographical areas. We have contacted the owner of the server to try to resolve this issue.
Q: I am unable to access the Lake Pend Oreille data from outside the U.S.
A: A static copy of this data is provided here for lynda.com members outside of the U.S | <urn:uuid:7762310a-ba52-47a2-9e21-28dd00790c7d> | 2.78125 | 1,219 | Tutorial | Software Dev. | 49.632898 | 95,630,386 |
Tigers can no more change their stripes than leopards can change their spots. That’s a good thing too, for their unchanging patterns, as individually distinct as a human fingerprint, make it easier to track any single tiger over time.
That process is about to become even simpler with a computer programme that creates a three-dimensional model of a tiger’s skin and can compare different shots of an animal taken at different times or angles. The programme is the brainchild of Lex Hilby from an organisation called Conservation Research and it could allow conservationists to track surviving tigers and to source the origins of poached skins.
Tigers are endangered and secretive animals and conservationists are increasingly relying on camera traps to take photos of them as they wander through the forests of Asia. The traps provide a series of tiger mug-shots, which trained experts can match to one another based on the pattern of stripes. That gives them valuable data about the population density of the tigers, how long individuals survive for, and how widely they travel.
But as you might imagine, matching photos by eye is a laborious job and it will only get harder as the library of tiger snaps gets larger. Hilby’s software is designed to get around that problem, by automating the search process and suggesting only images from the back-catalogue that have a good chance of matching any new photo.
Tigers don’t pose for camera-traps, so the software has to be able to cope with shots taken from a wide range of angles and with tigers adopting different postures. To do that, it creates a three-dimensional model of a tiger.
Users use coloured dots to indicate the position of the shoulder, hips and tail and the upper and lower margins of the image; the programme does the rest. It essentially unwraps the striped pattern from the tiger’s flank and works out how it would look if it were laid out flat. It then compares the new image to every existing one and gives them a score based on how similar they are. The software is freely downloadable, and you can even have a go yourself.
Ullas Karanth from the Wildlife Conservation Society has tested Hilby’s programme using photos of tigers taken in the Nagarhole and Bandipur reserves in India. Over the last two decades, his team have identified anywhere from 264 to 298 tigers by carefully comparing different images by eye. Hilby’s programme analysed all of these shots, and for each image, it ranked all the others in terms of how similar they were.
The test was a success. For every image, the programme managed to place a photo of the same individual in the top spot 95% of the time, and in the top five positions on every go. It even managed to match up photos where the animal’s stances were off by 66 degrees, or those that were taken up to seven years apart.
With such accuracy, Hilby is confident that the programme can successfully match a new image to a tiger already in the database, even if that individual is represented by a single photo. As the photo library grows, so too with the programme’s infallibility.
Hilby also showed that he can also use his programme forensically, to trace the origin of illegally sold tiger skins. He used it to trace the origins of three skins confiscated from poachers in the last four years. Each one was strongly matched to a tiger in the photo library, and only one image where the skin was partially crumpled, posed any difficulties.
The programme could certainly be improved – at the moment, users have to mark out the boundaries of the tiger in each image by hand. Even so, that takes but a few minutes; at the moment, searching the entire image catalogue takes anywhere from 30 to 45 minutes. And Hilby is optimistic that the photo-fitting step could also be automated in the future.
But even in its current state, there’s a lot of potential. The tiger programme is based on software that has previously been used for cheetahs and grey seals, and it could also be used to track individuals of other patterned species such as leopards, zebras and salamanders.
Reference: Biology Letters doi:10.1098/rsbl.2009.0028
More on using technology to study wildlife: | <urn:uuid:1ce230b6-979b-48ed-8e27-c1164d221bba> | 3.3125 | 898 | News Article | Science & Tech. | 43.871646 | 95,630,387 |
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Hawaii’s Kīlauea volcano has been erupting since May 3, and according to the county of Hawaii's civil defense agency, another small explosion occurred on Sunday morning.
The steam explosion spewed ash plumes over Ka'u, the southernmost district of the Big Island. The eruption happened 38 days after Kīlauea’s initial explosion which sent lava, ash and toxic gases throughout Hawaii’s largest island.
The Hawaiian Volcano Observatory reports that the eruption continues in the lower East Rift Zone. Fissure 8 continues to produce a large channelized flow that is entering the ocean at Kapoho Bay and producing a large laze plume.
A 5.3 magnitude volcanic eruption occurred early Monday morning about 3 miles west-southwest of the Kilauea Volcano, according to the USGS.
The earthquake was associated with an ash explosion that happened around 04:43 a.m. local time from the Halema'uma'u crater, the USGS reported.
Another 5.3 magnitude volcanic eruption occurred Tuesday morning. It happened about the same distance away from the volcano. This earthquake was also associated with an ash explosion from the Halema'uma'u crater, according to the USGS.
Kīlauea Message Tue, 12 Jun 2018 03:58:21 HST: At 1:52 AM HST, another small explosion occurred at Kīlauea's summit. This event and many of its precursory earthquakes were widely felt in the Volcano area. Ashfall may impact communities in the south part of the island.— USGS Volcanoes🌋 (@USGSVolcanoes) June 12, 2018
The Pacific Tsunami Warning Center reported no tsunami threats following these events.
The USGS also stated that this event's plume was similar to past events that have sent ash clouds up to 10,000 feet in the air and drifted southwest, with possible ash fall at downwind locations.
According to the county of Hawaii civil defense agency, severe conditions may exist such as inability to breathe and choking. The agency said this is a serious situation that affects the entire exposed population.
“I’m talking about 600 families. Don’t forget the farmers, don’t forget the ranchers, don’t forget all the employees for them,” Hawaii County Mayor Harry Kim said. Mayor Kim’s home was also destroyed by the volcano.
At least 700 homes have been destroyed by lava since he eruptions began, Kim told Hawaii News Now.
The lava that continues to spew from Kīlauea has reached a new high temperature of 2,140 degrees Fahrenheit.
"This is the hottest lava we've seen during this eruption," Wendy Stovall, a scientist with USGS, on Hawaii News Now said.
"Lava can't get hotter than where we are," Stovall said.
Kīlauea Message Sun, 10 Jun 2018 01:06:22 HST: At 12:51 AM HST, another small explosion occurred at Kīlauea's summit; equivalent magnitude was M5.4; event widely felt in Volcano area; based on past events, minor ashfall may occur on the south part of the island.— USGS Volcanoes🌋 (@USGSVolcanoes) June 10, 2018
Sulfur dioxide emissions coming from a number of ground fissures caused by the active volcano still remain elevated. The pungent chemical compound can cause respiratory problems in low doses and can be deadly when found in large concentrations.
Hawaii's Kīlauea Volcano: Lava flow claims more homes, evaporates entire lake
Hawaii's Kilauea Volcano remains active; Hundreds forced from homes
How Hawaii’s Kīlauea Volcano eruption compares to others around the world
Hawaiian Volcano Observatory reports volcanic gas emissions remain very high from fissure eruptions. Due to the elevated gas levels, if you feel the effects of gas exposure, shelter-in-place or leave the immediate area.
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Three people were injured after severe weather tore from Indiana to Kentucky and Tennessee to end the week.
A new round of severe weather is threatening lives from Ohio through Tennessee and will continue into Saturday morning.
In select regions of the world, people can live long enough to make some wonder if these countries have discovered the heavily sought-after fountain of youth.
A town in Iowa was severely damaged by a tornado on Thursday, while strong storms led to a tour boat disaster in Missouri that killed 17.
A boat carrying 31 people capsized on a lake near Branson, Missouri, as thunderstorms moved through the area on Thursday evening.
The risk of severe thunderstorms, including isolated tornadoes, will progress farther to the east and south over the central United States into Friday night.
Severe thunderstorms tracked across Iowa on Thursday afternoon with several tornadoes touching down across the state. | <urn:uuid:8279a5b8-3c04-4b0b-974e-002f943619a3> | 2.9375 | 1,070 | News Article | Science & Tech. | 47.412224 | 95,630,396 |
Methanogens sustain life under extremes of heat and cold
New research suggests that methanogens — among the simplest and oldest organisms on Earth — could survive on Mars.
Methanogens, microorganisms in the domain Archaea, use hydrogen as their energy source and carbon dioxide as their carbon source, to metabolize and produce methane, also known as natural gas. Methanogens live in swamps and marshes, but can also be found in the gut of cattle, termites and other herbivores as well as in dead and decaying matter.
Methanogens are anaerobic, so they they don’t require require oxygen. They don’t require organic nutrients and are non-photosynthetic, indicating they could exist in sub-surface environments and therefore are ideal candidates for life on Mars.
Rebecca Mickol, a doctoral student in space and planetary sciences at the University of Arkansas, subjected two species of methanogens to Martian conditions: Methanothermobacter wolfeii and Methanobacterium formicicum. Both species survived the Martian freeze-thaw cycles that Mickol replicated in her experiments.
The species were tested for their ability to withstand Martian freeze-thaw cycles that are below the organisms’ ideal growth temperatures: 37 degrees Celsius (98.6 degrees Fahrenheit) for M. formicicum and 55 degrees Celsius (131 degrees Fahrenheit) for M. wolfeii.
“The surface temperature on Mars varies widely, often ranging between minus 90 degrees Celsius and 27 degrees Celsius over one Martian day,” Mickol said. “If any life were to exist on Mars right now, it would at least have to survive that temperature range. The survival of these two methanogen species exposed to long-term freeze/thaw cycles suggests methanogens could potentially inhabit the subsurface of Mars.”
Mickol conducted the study with Timothy Kral, professor of biological sciences in the Arkansas Center for Space and Planetary Sciences and lead scientist on the project. She is presenting her work at the 2014 General Meeting of the American Society for Microbiology, being held May 17-20 in Boston.
The two species were selected because one is a hyperthermophile, meaning it thrives under extremely hot temperatures, and the other is a thermophile, which thrives under warm temperatures.
“The low temperature on Mars inhibited their growth, but they survived,” Mickol said. “Once they got back to a warm temperature, they were able to grow and metabolize again. I wanted to see if these cold temperatures would kill them, or if they were able to survive and adapt.”
Since the 1990s, Kral has been studying methanogens and examining their ability to survive on Mars. In 2004, scientists discovered methane in the Martian atmosphere, and immediately the question of the source became an important one.
“When they made that discovery, we were really excited because you ask the question ‘What’s the source of that methane?’” Kral said. “One possibility would be methanogens.”
Mickol is currently interning at the Kennedy Space Center in Florida. The NASA Exobiology Program funded her research.
The Arkansas Center for Space and Planetary Sciences, founded in 2000, is an interdisciplinary research institute at the University of Arkansas with 25 graduate students and nearly $3 million in awarded grants.
The University of Arkansas is the flagship institution of the University of Arkansas System and the premier research institution in the state. The Carnegie Foundation for the Advancement of Teaching categorizes the University of Arkansas in its highest research classification, a level that only 2 percent of American colleges and universities share.
Rebecca Mickol, doctoral student
Arkansas Center for Space and Planetary Sciences
Timothy Kral, professor, biological sciences
J. William Fulbright College of Arts and Sciences
Chris Branam | 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....
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MPQ scientists develop new methods to test the world view of macroscopic realism
In a classical world, objects have pre-existing properties, physical influences are local and cannot travel faster than the speed of light, and it is in principle possible to measure the properties of macroscopic systems without altering them.
Left: All reasonable physical theories, including quantum mechanics (QM), obey the no-signaling (NS) assumption. Local realism (LR) is tightly delimited by Bell inequalities (BI) which are therefore an optimal tool for experimental tests. NS, QM, and LR all live in a probability space with the same dimension; for simplicity the drawing is in two dimensions. Right: The picture is very different for macroscopic realism (MR). MR and QM live in probability spaces of different dimensions. The Leggett-Garg inequalities (LGI) are cuts through the QM space and do not tightly delimit MR. Hence, LGI are not optimal for experimental tests of MR. MPQ, Theory Division
This is referred to as local realism and macroscopic realism, and quantum mechanics is in strong contradiction with both of them. While Bell inequalities have been proven to be an optimal tool for ruling out local realism in quantum experiments, Lucas Clemente and Johannes Kofler from the Theory Division of the Max Planck Institute of Quantum Optics (MPQ) in Garching, Germany, have now shown that inequalities can never be optimal for tests of macroscopic realism.
Their results reveal a hitherto unknown radical difference in the mathematical structures of spatial and temporal correlations in quantum physics, and also provide a better tool for the search of Schrödinger cat-like states (PRL.116.150401, 15. April 2016).
Spin systems are a very simplified, stripped-down model of the interactions between particles making up a material. In the simplest of these models, each particle or “spin” can only be in one of two possible states: “up” or “down”. The interactions between neighbouring particles try to align them either in the same or in the opposite direction, which is known as the Ising model, after the physicist Ernst Ising who studied it in his 1924 PhD thesis.
“Models in different dimensions or with different kinds of symmetries show very different physical behaviour. Our study shows that if one considers models with irregular coupling strengths, all these differences disappear as they are all equivalent to universal models,” says Dr. Gemma De las Cuevas from the MPQ, Munich Local realism is the classical world view which assumes that objects have pre-existing properties and no influence can travel faster than the speed of light.
In 1964, John Bell found that these assumptions put boundaries on the possible correlations between measurements on spatially separated objects. In local realism, spatial correlations need to obey certain inequalities, which are today called Bell inequalities.
In 1984, Arthur Fine proved that Bell inequalities are optimal in the sense that they form a tight boundary for all local realist theories. That means that the set of all Bell inequalities is both necessary and sufficient for local realism: all local realist theories obey the Bell inequalities and, in turn, obeying all Bell inequalities means that there is a local realist explanation for the observed data. Using entangled quantum states between two or more systems, such as photons or atoms, Bell inequalities can be violated. Such quantum violations were measured repeatedly over the past decades with ever increasing perfection. Thus, the world view of local realism has been conclusively ruled out experimentally.
Although quantum mechanics violates local realism, it does not allow for the transmission of information faster than light. This assumption of no-signalling is one of the pillars of special relativity theory. A violation of no-signalling would be in contradiction with causality and allow communication into the past. Quantum experiments can therefore only violate Bell inequalities, but not the no-signalling assumption.
Equally strange as the quantum violation of local realism is the famous paradox of Schrödinger’s cat, where – in a thought experiment – a cat can be put into a superposition of being both dead and alive. Until today, many physicists accept superposition states of microscopic objects but are deeply unsatisfied with the fact that quantum mechanics would in principle allow such a strange behaviour also on the macroscopic scale. The classical world view called macroscopic realism forbids such macroscopic superposition states and asserts that macroscopic objects can in principle be measured without altering their state.
In 1985, Anthony Leggett and Anupam Garg showed that macroscopic realism puts a bound on the possible temporal correlations of sequential measurements performed on a single quantum system. These temporal correlations need to obey inequalities, which are now called Leggett-Garg inequalities.
In the past years, Leggett-Garg inequalities were violated in many experiments, albeit only with microscopic quantum systems, which did not rule out macroscopic realism. Whether or not one can put macroscopic objects, such as cats, in superpositions is experimentally not yet decided and is one of the most exciting open questions in the foundations of physics.
Although local realism is about correlations in space between at least two systems, and macroscopic realism is about correlations in time of a single object, the two concepts have many analogies, and the corresponding Bell and Leggett-Garg inequalities are almost identical mathematically. However, the work of Clemente and Kofler has now revealed a remarkable and hitherto unknown disanalogy. With a sophisticated dimensional analysis of probability spaces they were able to prove that Fine’s theorem for local realism does not apply for macroscopic realism. In other words, Leggett-Garg inequalities do not form an optimal tight boundary for macrorealistic theories like Bell’s inequalities do for local realism (see Figure).
Interestingly, it is the temporal analogy to the no-signalling assumption, which does the trick. This assumption, called no-signalling in time, demands that for macroscopic objects later measurement outcomes cannot depend on earlier measurements. It holds in macroscopic realism but is violated in quantum mechanics. “In contrast to the Leggett-Garg inequalities, the combination of all no-signalling in time conditions is both necessary and sufficient for macroscopic realism. This reveals a striking difference between spatial correlations in tests of local realism and temporal correlations in tests of macroscopic realism”, Clemente explains.
Consequently, experimentalists aiming at violating macroscopic realism should stop focusing on the Leggett-Garg inequalities, which they have done for so many years now. “Leggett-Garg inequalities unnecessarily limit the parameter space in which potential violations of macroscopic realism can be found. No-signalling in time is not only a better but even optimal condition for experiments which try to test whether there can be Schrödinger cats in nature”, Kofler adds. [LC/JK]
Lucas Clemente and Johannes Kofler
No Fine theorem for macrorealism: Limitations of the Leggett-Garg inequality
Phys.Rev.Lett.116.150401, DOI:10.1103, 15 April 2016
Dr. Johannes Kofler
Max Planck Institute of Quantum Optics
85748 Garching, Germany
Phone: +49 (0)89 / 32 905 - 242
Dr. Olivia Meyer-Streng
Press & Public Relations
Max Planck Institute of Quantum Optics
Phone: +49 (0)89 / 32 905 - 213
Dr. Olivia Meyer-Streng | Max-Planck-Institut für Quantenoptik
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Space physics from University of Helsinki gets its first-ever International Space Science Institute team
Lucile Turc to work on mystery waves that transmit in the near-Earth space.
For the very first time space physics at University of Helsinki gets an International Space Science Institute (ISSI) team. It is Marie Curie Fellow Lucile Turc that will head an international space science team to investigate one of the great mysteries in space physics that has been under research for a long time without any answers. There has not been enough data or good enough models to do that, so far.
”This mystery is about how some electromagnetic waves travel through our near-Earth space, while no one knows why and how. We know where these waves come from, a very turbulent region just beyond the magnetic bubble formed by our planet’s magnetic field. We know that these waves somehow enter our magnetic bubble, because we observe them in there, and even at the Earth’s surface. But what happens in between has so far eluded us. These waves are critical e.g. in understanding the radiation environment,” Lucile Turc says.
Vlasiator code can describe the processes from which the waves originate
In the recent years, more and more scientific spacecraft have collected data in the different regions of near-Earth space. Also, novel supercomputer models, such as the Vlasiator code developed at the University of Helsinki, can now describe the small processes from which the waves originate in their global context, the whole near-Earth space.
Combining these measurements and modelling tools now makes it possible to track the waves throughout their journey towards the Earth, but requires a wide-ranging expertise.
“That’s where the ISSI team comes into play: it brings together scientists from different background, to finally solve the mystery of the waves’ propagation,” Lucile Turc says.
The International Space Science Institute (ISSI) is an organisation for a deeper understanding of the results from different space missions, ground based observations and laboratory experiments worldwide. The setting is multi- and interdisciplinary, and to foster international networking, the institute selects, after a highly competitive evaluation, international teams to reach out for new scientific horizons.
“To get an ISSI team means that the team leader may gather a group of exceptional international scientists from all over the world to work with,” Professor Minna Palmroth of University of Helsinki explains.
Global Study of the Transmission of Foreshock ULF Waves into the Magnetosheath and the Magnetosphere, Turc and Palmroth, on the selected science objective list by ISSI: http://www.issibern.ch/program/teams.html
The team’s website: http://www.issibern.ch/teams/foreshockulf/
Lucile Turc’s website: https://blogs.helsinki.fi/luciletu/
Minna Meriläinen-TenhuPress Officer+358 50 415 firstname.lastname@example.org
P.O. Box 53
00014 University of Helsinki, Finland
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Haluatko tietää asioista jo ennen kuin ne uutisoidaan? Kun tilaat tiedotteemme, saat ne sähköpostiisi yhtä aikaa suomalaisen median kanssa. Tilauksen voit halutessasi perua milloin tahansa.
Lue lisää julkaisijalta University of Helsinki
The glacier in Basin 3, Austfonna Ice-cap, Svalbard, is moving faster than before – summer melt water could be one of the causes7.2.2018 16:07 | Tiedote
Numerical simulations provide a way to link the melt at the glacier surface to the hydrology system at the glacier bed to explain the surge in Basin 3, Austfonna Ice-cap, Svalbard. This is shown in a fresh doctoral thesis on ice flow modeling of ice shelves and ice caps by Yongmei Gong from the University of Helsinki.
New methods to estimate rainfall and how icing affects wind energy29.1.2018 16:19 | Tiedote
Accurate meteorological analysis products merge information from various observation instruments a new study shows. Erik Gregow is defending his doctoral thesis on February the 9th at the University of Helsinki. He found out that thunder lightning information is useful when we need to estimate the rain amount; he also presents new modelling results on how icing affects the wind energy.
Stunning video and photo material from Antarctica available for online sharing21.10.2017 09:00 | Tiedote
Researchers going on a six-week long diving expedition under the Antarctic sea ice, invite media to follow and share the experience with their audiences.
The Internet of empathy receives the Helsinki Challenge prize of €250,00013.11.2015 21:49 | Tiedote
The €375,000 prize for the science-based idea competition Helsinki Challenge was divided between two teams.
New technology destroys cancerous tumours9.11.2015 13:55 | Tiedote
University of Helsinki will present 15 of the most promising research-based innovations and two new spin-out companies at the Slush event in Helsinki.
The Helsinki Challenge Science based Competition - finalists are here!1.10.2015 16:03 | Tiedote
University of Helsinki launched an international science-based competition, the Helsinki Challenge, to celebrate its 375th anniversary.
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By: RE Kohler
344 pages, 35 b/w photos, 9 line illus, 3 tabs
The common fruit fly, Drosophila, has become a standard laboratory animal; many modern genetic findings are based on research on Drosophila. This book examines the use of this insect, and the culture and customs of those who study it.
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Impact of 10–60-Day Low-Frequency Steering Flows on Straight Northward-Moving Typhoon Tracks over the Western North Pacific
This study investigates the impact of low-frequency (intraseasonal and interannual) steering flows on straight northward-moving (defined as a meridional displacement two times greater than the zonal displacement) typhoons over the western North Pacific using observational data. The year-to-year change in the northward-moving tracks is affected by the interannual change in the location and intensity of the subtropical high. A strengthened northward steering flow east of 120°E and a weakened easterly steering flow south of the subtropical high favor more frequent straight northward tracks. Examining each of the individual northward-moving typhoons shows that they interact with three types of intraseasonal (10–60-day) background flows during their northward journey. The first type is the monsoon gyre pattern, in which the northward-moving typhoon is embedded in a closed cyclonic monsoon gyre circulation. The second type is the wave train pattern, where a cyclonic (anticyclonic) vorticity circulation is located to the west (east) of the northward-moving typhoon center. The third type is the mid-latitude trough pattern, in which the northward-moving typhoon center is located in the maximum vorticity region of the trough.
Key wordsintraseasonal steering flow interannual steering flow straight northward-moving typhoon
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We greatly appreciate the constructive comments from the anonymous reviewers and Dr. Mingyu Bi.
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Eruptions, Earthquakes & Emissions
The Smithsonian's "Eruptions, Earthquakes, & Emissions" web application (or "E3") is a time-lapse animation of volcanic eruptions and earthquakes since 1960. It also shows volcanic gas emissions (sulfur dioxide, SO2) since 1978 — the first year satellites were available to provide global monitoring of SO2. The eruption data are drawn from the Volcanoes of the World (VOTW) database maintained by the Smithsonian's Global Volcanism Program (GVP). The earthquake data are pulled from the United States Geological Survey (USGS) Earthquake Catalog. Sulfur-dioxide emissions data incorporated into the VOTW for use here originate in NASA's Multi-Satellite Volcanic Sulfur Dioxide L4 Long-Term Global Database. Please properly credit and cite any use of GVP eruption and volcano data, which are available via a download button within the app, through webservices, or through options under the Database tab above. A citation for the E3 app is given below.
Clicking the image will open this web application in a new tab.
Global Volcanism Program, 2016. Eruptions, Earthquakes & Emissions, v. 1.0 (internet application). Smithsonian Institution. Accessed 21 Jul 2018 (https://volcano.si.edu/E3/).
What is the Volcanic Explosivity Index (VEI)?
VEI is the "Richter Scale" of volcanic eruptions. Assigning a VEI is not an automated process, but involves assessing factors such as the volume of tephra (volcanic ash or other ejected material) erupted, the height the ash plume reaches above the summit or altitude into the atmosphere, and the type of eruption (Newhall and Self, 1982). VEIs range from 1 (small eruption) to 8 (the largest eruptions in Earth's entire history).
What about eruptions before 1960?
For information about volcanic eruptions before 1960, explore the GVP website, where we catalog eruption information going back more than 10,000 years. This E3 app only displays eruptions starting in 1960 because the catalog is much more complete after that date. For most eruptions before the 20th century we rely on the geologic record more than historical first-hand accounts — and the geologic record is inherently incomplete (due to erosion) and not fully documented.
What are "SO2 emissions" and what do the different circle sizes mean?
The E3 app displays emissions of sulfur dioxide gas (SO2) from erupting volcanoes, including the mass in kilotons. Even though water vapor (steam) and carbon dioxide gas (see more about CO2 below) are much more abundant volcanic gases, SO2 is the easiest to detect using satellite-based instruments, allowing us to obtain a global view. There is no universally accepted "magnitude" scale for emissions; the groupings presented here were chosen to best graphically present the relative volumes based on available data.
What am I seeing when I click on an SO2 emission event?
You are seeing a time-lapse movie of satellite measurements of SO2 associated with a particular emission event. These SO2 clouds, or plumes, are blown by winds and can circle the globe in about a week. As plumes travel, they mix with the air, becoming more dilute until eventually the concentration of SO2 falls below the detection limit of satellites. Earth's entire atmosphere derives from outgassing of the planet — in fact, the air you breathe was once volcanic gas, and some of it might have erupted very recently!
Why are there no SO2 emissions before 1978?
E3 shows volcanic gas emissions captured from satellite-based instruments, which were first deployed in 1978. NASA launched the Total Ozone Mapping Spectrometer (TOMS) in 1978, which provided the first space-borne observations of volcanic gas emissions. Numerous satellites capable of measuring volcanic gases are now in orbit.
Why don't you include H2O and CO2 emissions?
The most abundant gases expelled during a volcanic eruption are water vapor (H2O in the form of steam) and carbon dioxide (CO2). Sulfur dioxide (SO2) is typically the third most abundant gas. Hydrogen gas, carbon monoxide and other carbon species, hydrogen halides, and noble gases typically comprise a very small percentage of volcanic gas emissions. So why can't we show H2O and CO2 in the E3 app? Earth's atmosphere has such high background concentrations of H2O and CO2 that satellites cannot easily detect a volcano's signal over this background "noise." Atmospheric SO2 concentrations, however, are very low. Therefore volcanic emissions of SO2 stand out and are more easily detected by satellites. Scientists are just beginning to have reliable measurements of volcanic carbon dioxide emissions because new satellites dedicated to monitoring CO2 have either recently been launched or have launches planned for the coming decade.
How much carbon is emitted by volcanoes?
We don't really know. CO2, carbon dioxide, is the dominant form of carbon in most volcanic eruptions, and can be the dominant gas emitted from volcanoes. Humans release more than 100 times more CO2 to the atmosphere than volcanoes (Gerlach, 2011) through activities like burning fossil fuels. Because of this, the background levels of CO2 in the atmosphere have risen to levels that are so high (greater than 400 parts per million, or 0.04%) that satellites cannot easily detect the CO2 from volcanic eruptions. Scientists are able to estimate the amount of carbon flowing from Earth's interior to exterior (the flux) by measuring carbon emissions directly at volcanic vents and by measuring the carbon dissolved in volcanic rocks. Scientific teams in the Deep Carbon Observatory (one of the supporters of E3) are working to quantify the flux of carbon from Earth's interior to exterior.
Do volcanic emissions cause global warming?
No, not in modern times. The dominant effect of volcanic eruptions is to cool the planet in the short term. This is because sulfur emissions create aerosols that block the sun's incoming rays temporarily. While volcanoes do emit powerful greenhouse gases like carbon dioxide, they do so at a rate that is likely 100 times less than humans (Gerlach, 2011). Prior to human activity in the Holocene (approximately the last 10,000 years), volcanic gas emissions did play a large role in modulating Earth's climate.
Volcanic eruptions and earthquakes seem to occur in the same location. Why?
Eruptions and earthquakes occur at Earth's plate boundaries — places where Earth's tectonic plates converge, diverge, or slip past one another. The forces operating at these plate boundaries cause both earthquakes and eruptions. For example, the Pacific "Ring of Fire" describes the plate boundaries that surround the Pacific basin. Around most of the Pacific Rim, the seafloor (Earth's oceanic crust) is "subducting" beneath the continents. This means that the seafloor is being dragged down into Earth's interior. You might think of this as Earth's way of recycling! In this process, ocean water is released to Earth's solid rocky mantle, melting the mantle rock and generating magma that erupts through volcanoes on the continents where the plates converge. In contrast, mid-ocean ridges, chains of seafloor volcanoes, define divergent plate boundaries. The Mid-Atlantic Ridge that runs from Iceland to the Antarctic in the middle of the Atlantic Ocean is one example of a divergent plate boundary. Earth's crust is torn apart at the ridge, as North and South America move away from Europe and Africa. New lava erupts to fill the gap. This lava cools, creating new ocean crust. All these episodes where solid rock collides or is torn apart generate earthquakes. And boom! You have co-located eruptions and earthquakes. To learn more about plate margins using E3, watch this video.
Is this the first time eruptions, emissions, and earthquakes have been animated on a map?
E3 is a successor to the program Seismic/Eruption developed by Alan Jones (Binghamton University). That program was one of the first to show the global occurrence of earthquakes (USGS data) and eruptions (GVP data) through space and time with animations and sound. The program ran in the Smithsonian's Geology, Gems, and Minerals Hall from 1997 to 2016, and was also available on the "Earthquakes and Eruptions" CD-ROM. E3 builds upon Seismic/Eruption with the addition of emissions data and automated data updates.
How many eruptions and emissions are shown, and from how many volcanoes?
The application is currently showing 2,050 eruptions from 334 volcanoes. It is also showing 360 emission activity periods from 118 different volcanoes. In addition, there are 67 animations available showing the movement of SO2 clouds from 44 volcanoes.
How often do you update the data represented in the web application?
The application checks for updates once a week. Earthquake data, being instrumentally recorded, is typically very current. Eruption data, which relies on observational reports and analysis by GVP staff, is generally updated every few months; however, known ongoing eruptions will continue through the most recent update check. Emissions data is collected by satellite instruments and also must be processed by scientists, so updates will be provided as soon as they are available following an event, on the schedule with eruption updates.
Is my computer system/browser supported? Something isn't working right.
To run the map, your computer and browser must support WebGL. For more information on WebGL, please visit https://get.webgl.org to test if it should work. | <urn:uuid:59acfa35-0b8d-455f-84af-e050035c8c94> | 3.65625 | 2,034 | Knowledge Article | Science & Tech. | 40.881415 | 95,630,492 |
- Open Access
The evolutionary history of effectors downstream of Cdc42 and Rac
© BioMed Central Ltd 2002
Published: 14 January 2002
Cdc42 and Rac - ancient, highly conserved, small GTPases - mediate extracellular signals, triggering changes in transcription and in the actin cytoskeleton. Although dozens of proteins act downstream of these GTPases, a comparison of effector proteins from evolutionarily diverse organisms suggests that six groups of proteins serve as the core machinery for signaling from Cdc42 and Rac.
Reorganization of the actin cytoskeleton plays crucial roles in many cellular functions, including morphology, motility, and adhesion. Regulation of actin polymerization and depolymerization is orchestrated by small GTPases of the Rho family; these proteins are also important in regulating gene transcription. The basic signaling properties of two major subgroups of Rho GTPases - the Cdc42 and Rac subfamilies - are highly conserved amongst all eukaryotes, but the means by which they act are not well understood. In an effort to understand the fundamental signaling elements, or 'core machinery', required for the function of these GTPases, we describe here the conservation and functional similarities of Cdc42 and Rac effectors in five different species: plant, yeast, fruit fly, roundworm and human. We focus on six 'core' effectors that operate in almost all these species - members of the Pak, WASP/WAVE, formin, lipid-kinase, IQGAP and NADPH oxidase families. Additional modules that have been added during the evolution of particular lineages are not considered in detail here.
Core functions of Rho GTPases
Rho GTPases are small (20-30 kDa) GTP-binding proteins of the Ras superfamily. The Rho subfamily is divided in three main subgroups - Cdc42, Rac, and Rho - examples of which are represented in all eukaryotes from plants to man. The mammalian Rho family consists of at least sixteen distinct members: the Cdc42 subgroup (Cdc42, TC10, Chp, and Wrch-1); the Rac subgroup (Rac1-Rac3); and the Rho subgroup (RhoA-RhoE, RhoG, RhoH, Rnd1, and Rnd2). In this article, we focus on the signaling mechanisms of two of these three subgroups, Cdc42 and Rac, as they are often linked in their physiological functions and have several effectors in common.
Cdc42 and/or Rac homologs are found in fruit flies, round-worms and budding yeast. Interestingly, small GTPases related to Rac are found even in organisms that lack Ras, such as plants. This broad distribution across widely divergent eukaryotic species suggests that Cdc42 and Rac GTPases have an ancient origin, perhaps even predating that of their cousin Ras. The analysis of Cdc42 and Rac function in evolutionarily distant organisms is useful as a tool to uncover the basic activities of these proteins. In all systems, these GTPases are best known for their effects on the polymerization and distribution of actin in the cell cortex . This activity is strongly conserved and probably represents a primordial function of these proteins. By regulating filamentous actin, Cdc42 and Rac exert a profound effect on cell shape, polarity, migration, cell:cell and cell:matrix adhesion, protein traffic, and cytokinesis. In addition, they play important roles in gene transcription (via activation of mitogen activated protein (MAP) kinase pathways and, in higher eukaryotes, the transcription factor NFκB), generation of reactive oxygen species, apoptosis, and cell-cycle progression.
Core GTPase effectors
Cdc42 and Rac effectors
Actin polymerization; cell polarity; cytokinesis
Actin organization; regulation of cell-cell contacts
Phosphatidic acid levels; maybe also actin regulation
PIP3 levels; actin organization
PIP2 levels; actin organization
ROS production; apoptosis
Phosphatidic acid levels; cytoskeletal reorganization
Actin organization; MAPK/Jnk activation; apoptosis
Transcription; cell-cycle progression; RNA processing
Although the total number of Rac and Cdc42 effectors is not yet known for any organism, it is already sufficiently high that an analysis of the role of individual effectors is difficult. For example, in mammalian cells, the identities and relative contributions of the Cdc42/Rac effectors that mediate activation of the Jnk family of kinases are in dispute, with competing claims made for the Pak, MEKK and MLK kinases and for the adaptor protein POSH [6,7]. Similarly, the relative contributions of various Cdc42/Rac-binding protein kinases to actin reorganization are far from settled. Several approaches have therefore been taken in an attempt to elucidate the precise role of Cdc42/Rac effector proteins. For example, gene deletions have been used to analyze the role of Cdc42 effectors in budding yeast. In mammalian cells, loss-of-function studies of Cdc42 and Rac effectors are less complete, and overexpression studies, using constitutively active or dominant-negative mutants, have instead been the predominant methods of analysis. Several groups have also analyzed the signaling properties of Cdc42 and Rac mutants that selectively bind certain sets of effector proteins [8,9,10]. In general, these kinds of studies have been more useful in excluding effectors from a given Cdc42/Rac function than in proving their involvement.
Paks are serine/threonine protein kinases that associate with Cdc42, and usually also with Rac, via a conventional CRIB motif. The Pak family in mammals has six members, which can be further divided into two groups on the basis of structure . Plant genomes do not encode any Paks, but both the budding and the fission yeast genomes encode multiple Pak homologs that are critical to cell polarity, mating, and cytokinesis. In the budding yeast Saccharomyces cerevisiae, the Pak homolog Ste20p phosphorylates the MEKK-like protein kinase Ste11p, and thus activates the mating and filamentous growth MAP kinase pathways . A similar arrangement is found in the fission yeast Schizosaccharomyces pombe, in which Pak1 and Pak2 act upstream of MAP kinase cascades [12,13]. Given that these two yeasts are only distantly related (having diverged around 800 million years ago), these data support the idea that Paks constitute a conserved and fundamental link from Rho GTPases to MAP kinase cascades. This notion is supported by data from mammals, in which Paks have also been shown to function in MAP kinase activation, albeit in a more baroque manner than in yeast. Here, the linkage is through the kinases Raf1 and Mek1, which Pak phosphorylates [14,15]. Such phosphorylations are not in themselves sufficient for MAP kinase activation, but rather are permissive events: they promote efficient coupling of Raf to Ras and of Mek to Raf, respectively. There is also evidence that Paks may mediate Cdc42 and Rac signaling to stress-activated kinases such as Jnk and p38. The effects of Paks on these stress-kinase cascades are not robust, however, and there is as yet no evidence that Pak acts directly on any MEKKs.
In addition to their effects on MAP kinase cascades, Paks also play an important role in regulating cell morphology. In budding yeast, the Pak Ste20p phosphorylates myosin I and is also associated with the scaffold proteins Ste5p and Bem1p, both of which interact with actin. One other Pak target of note in yeast is the guanine-nucleotide exchange factor (GEF) Cdc24p, which is inactivated as a consequence of phosphorylation. By phosphorylating Cdc24p, the Pak homolog Cla4p provides a feedback inhibition to terminate Cdc42p action as the cell cycle progresses . Thus, Paks in budding yeast link a Rho family GTPase (Cdc42p) to the cell polarity and morphology apparatus via a variety of cytoskeletal targets. In metazoans, the same general rules seem to apply. The fruit fly and worm genomes each encode at least one enzyme from each Pak subgroup, and genetic analysis in Drosophila indicates that these different forms of Pak play distinct roles in embryogenesis: DPak (a group I Pak) is genetically linked to Dock (an adaptor protein homologous to mammalian Nck), Trio (a Rac GEF), and Rac, and is involved in axon guidance [17,18], whereas mbt (which encodes a group II Pak), is required for normal development of the mushroom body, which is thought to be the seat of memory formation in flies . The relevant targets for DPak and Mbt are not known. In man, mutations in the brain-specific Pak3 gene are associated with mental retardation [20,21].
The sum of the genetic data is consistent with the notion that one of Pak's oldest functions is to regulate actin dynamics. These data are supported by overexpression experiments in mammalian cells, which suggest that Paks play a key role in actin polymerization and in cell motility (reviewed in ). In higher eukaryotes, two relevant Pak targets are LIM kinase and myosin light chain kinase (MLCK), which control actin dynamics via their substrates cofilin and myosin light chain, respectively . When activated LIM kinase phosphorylates cofilin, cofilin becomes inactive and promotes stabilization of actin filaments, whereas the phosphorylation of MLCK decreases its ability to phosphorylate and activate the regulatory light chain of myosin. The tumor suppressor Merlin has recently emerged as a third potentially important target that might mediate Pak's cytoskeletal effects in mammalian cells . Merlin belongs to the Ezrin/Radixin/Moesin family of proteins, which are thought to link actin filaments to the plasma membrane. Pak phosphorylates Merlin, downregulating Merlin's activity. Finally, stathmin, a protein that regulates microtubule stability, is also a direct target of Pak . Stathmin may link Cdc42, via Pak, to the tubulin cytoskeleton.
WASPs and WAVEs
WASPs and WAVEs represent another class of ancient small-GTPases effectors and are likely to be essential for small-GTPase function in all eukaryotes. In mammals, there are two forms of these proteins, the WASPs, which are activated by Cdc42, and the WAVEs, which are activated by Rac. WASP/WAVE homologs are found in Drosophila, Caenorhabditis elegans, and yeast. Interestingly, while the WASPs contain a recognizable CRIB motif, the WAVEs do not. Instead, their linkage to small GTPases is thought to be provided by an adaptor protein, IRSp53 , although its precise role is controversial . In budding yeast, a similar arrangement may prevail, as the WASP/WAVE homolog Bee1p lacks a CRIB motif but is associated with Cdc42p indirectly via a formin . Disruption of WASP/WAVE function has major consequences for actin organization in every system where it has been studied. In budding yeast, loss of Bee1p leads to a severe defect in cortical actin-patch assembly , while in fruit flies WASP has an essential role in lineage decisions mediated by the Notch signaling pathway . In man, mutations in WASP lead to severe immunodeficiency (the Wiskott Aldrich syndrome, from which the protein takes its name); this disorder is characterized at the cellular level by abnormalities of cytoskeletal structure, polarization, and motility. WASP has been shown to regulate actin polymerization by stimulating the actin-nucleating activity of the Arp2/3 complex . The binding to WASP of GTP-Cdc42 (via the CRIB motif) and phosphatidylinositol bisphosphate, PIP2 (via a pleckstrin-homology lipid-interaction domain), induces WASP activation by opening the normally masked and auto-inhibited carboxy-terminal WASP domain that binds Arp2/3. In this way, WASP regulates the position of newly assembled actin filaments.
Formins are a diverse group of proteins defined by the presence of two regions of sequence homology, an approximately 100 amino-acid, proline-rich region termed FH1 (formin-homology 1), and an approximately 130 amino-acid region termed FH2 . Many members of the formin family affect both the actin and the tubulin cytoskeletons, but it is not clear if all proteins with FH domains retain these functions. For example, Arabidopsis encodes at least eight proteins with FH domains, but their unusual structures (for example, including both signal peptides that indicate secretion and transmembrane motifs) suggests that these proteins have functions that are unique to plants . In fungi, including yeast, and in animal cells, several formins are known to bind to activated Rho-family GTPases and are implicated in cytoskeletal regulation. In budding yeast, the formin Bni1p is associated, via its amino terminus, with Cdc42p, and, via its FH1 domain, with profilin and Bud6p, both of which regulate actin dynamics . Mutations in BNI1 lead to defects in cortical actin patch assembly. In Drosophila, the gene encoding the formin protein Diaphanous is required for cytokinesis . Embryos lacking Diaphanous show fatal defects in actin-filament organization that result in abnormalities in formation of the metaphase furrow, in cellularization, and in the formation of pole cells . In C. elegans, the formin Cyk-1 co-localizes with actin filaments at the cleavage furrow of dividing cells, and loss of Cyk-1 function leads to abnormal polar-body extrusion during meiosis and aberrant cytokinesis during embryonic mitosis . There is no biochemical or genetic evidence, however, that either Diaphanous or Cyk-1 is linked to small GTPases. In mammals, formins have been firmly associated with both Rho and Rac.
Mammalian formins, such as the Diaphanous homologs mDia1 and mDia2, play a key role in the formation of stress fibers (a Rho function) as well as cytokinesis and Rho-mediated transcriptional activation of the serum response factor . How these effects are achieved is not known, but the mDia proteins, like yeast Bnip, do associate with profilin . Recently, another member of the formin family, termed FHOS, has been shown to bind activated Rac1 rather than Rho . Like the mDia proteins, PHOS regulates the activation of the serum response factor by a GTPase (Rac). Unlike budding yeast formins, however, mammalian formins have not been found to associate with Cdc42. A formin-binding protein is closely related to the Cdc42 effector protein CIP4, raising the interesting possibility that some formins could be indirectly linked to Cdc42 . Thus, formins are ancient, highly conserved effectors for Rho-family GTPases that, like Paks, mediate both cytoskeletal and transcriptional responses.
Two lipid kinases, phosphatidylinositol 3-kinase (PI 3-kinase) and phosphatidylinositol-4-phosphate 5-kinase (PI 5-kinase), have been found to act downstream of Rho GTPases. Whether PI 3-kinase represents a core Cdc42/Rac effector, as defined in this article, is debatable, as the evidence for a relationship between PI 3-kinase and Cdc42/Rac is confined to mammalian systems, but PI 5-kinase is known to act as a cytoskeletal effector for Rac homologs in both man and plants [41,42,43]. PI 5-kinase generates the lipid PIP2 which is an important second messenger in the regulation of actin cytoskeletal dynamics; it uncaps actin filaments (primarily by binding to actin-capping proteins) and thus allows for their further polymerization. PI 5-kinase activity is physically associated with the Rac-related Rop proteins in plants and is thought to regulate calcium fluxes and actin dynamics . In S. cerevisiae, the PI 5-kinase Mss4p is required for normal actin dynamics and is genetically linked to RHO2, but the nature of this relationship is undefined . Homologous PI 5-kinases are expressed in fruit flies and roundworms, but they have not been linked to Cdc42, Rac, or Rho GTPases in these organisms. In mammalian cells, Rac and Rho interact directly with PI 5-kinase. Blockade of PI 5-kinase activity by overexpressing a kinase-dead PI 5-kinase mutant blocks Rac-induced actin assembly, and Rac mutants that cannot bind PI 5-kinase fail to assemble actin in vitro . These results demonstrate that PI 5-kinase is a critical mediator of Rac-dependent actin assembly.
In spite of their name, IQGAPs have no GTPase-activating activity. Instead, these highly-conserved proteins are bona fide cytoskeletal effectors for Cdc42 and Rac. IQGAPs are broadly distributed: homologs have been found in yeast, Hydra, Dictyostelium, C. elegans, and many other eukaryotes, though not, surprisingly, in Drosophila. In S. cerevisiae Iqg1p is involved in actin recruitment to the bud neck [46,47]; it promotes cytokinetic actin ring formation and is required for cytokinesis and viability. Iqg1p acts as a scaffold to recruit and localize a protein complex involved in actin-based cellular functions, and thus mediates the regulatory effects of Cdc42p on the actin cytoskeleton . A similar actin-filament bundling function has been proposed for mammalian IQGAPs . In mammalian cells, IQGAPs interact with both GTP-Rac1 and GTP-Cdc42, and localize to membrane ruffles. IQGAP1 has been detected in a complex with filamentous actin and Cdc42, and has been shown to localize to cell-cell adhesion sites. It has also been detected in a complex with Cdc42 and the Golgi apparatus . The combined genetic and biochemical data on IQGAPs suggest that these proteins are Cdc42/Rac effectors that contribute to proper actin organization, particularly during cytokinesis.
In mammalian cells, Rac is well-known as a regulator of the NADPH oxidase complex, a specialized enzyme of phagocytic cells that generates oxygen radicals to kill internalized microorganisms. A cytoplasm-derived component of the oxidase complex, p67Phox, binds directly to Rac1 and Rac2 in neutrophils . These data suggest that Rac acts as an allosteric regulator by inducing a conformational change in the preformed NADPH complex to promote catalytic activity. The pathogen-defense function of Rac has ancient origins. In plants, the Rac-related Rop proteins are involved in the elicitor-induced production of reactive oxygen species (ROS), products of an oxidative burst reaction that induces the death of infected host cells. As in the oxidative burst in mammalian neutrophils, ROS production in plants is carried out by an NADPH oxidase enzyme complex that contains a Rho-family GTPase (reviewed in ). In rice, over-expression of a dominant-negative Rop (OsRac1) inhibits ROS production and cell death in cells treated with the protein phosphatase inhibitor calyculin A, while constitutively active OsRac1 induces resistance of rice plants against a virulent blast fungus. These findings suggest a role for Rop in general disease resistance in rice. Rac-regulated H2O2 production is also involved in a second, developmental process, namely cell-wall formation in cotton fibers (and probably in other plants as well). In mammalian cells, Rac-regulated ROS production is not limited to pathogen-defense by neutrophils: it also has a key function in cell growth and transformation. Activated Cdc42 or Rac proteins that lack the 'insert domain' (a carboxy-terminal motif that is found in all three Rho GTPase subgroups, but not in other small GTPases) fail to elicit ROS production in fibroblasts, and, unlike the full-length proteins, fail to support neo-plastic transformation [52,53]. The targets for ROS that mediate these effects have not been identified, but protein tyrosine phosphatases, most of which negatively regulate mitogenic signaling and which are known to be exquisitely sensitive to oxidation, are prime candidates.
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For nearly 200 years, scientists have known that the elements molybdenum and oxygen can form various large molecules, which usually impart a unique blue color to aqueous solutions. Only recently have scientists been able to isolate these molecules, but no one was able to explain their supramolecular structure in solution, until now. In a paper scheduled to appear in an upcoming issue of the Journal of the American Chemical Society (available online August 20), Tianbo Liu, a physicist at the U.S. Department of Energys Brookhaven National Laboratory, describes the unique "blackberry" structure, which may represent a new, stable solute state never seen before.
"The nature of molybdenum blue solutions has remained a fascinating enigma for inorganic chemists since the late 1700s and early 1800s," said Liu. In 1826, scientists discovered the first so-called polyoxomolybdate (POM) molecules with a chemical formula of Mo5O14, and realized that the electronic state of the molybdenum atoms was responsible for the blue color in solution. However, the molybdenum blue solutions contained many more complicated molecules. For a long time, scientists were unable to isolate these molecules.
Recently, however, scientists have isolated several different polyoxomolybdate molecules from various molybdenum blue solutions -- all "giant" compared to other inorganic molecules (see http://www.bnl.gov/bnlweb/pubaf/pr/2002/bnlpr_spotlights_2002.htm). Unlike other water-soluble inorganic compounds, such as common table salt (NaCl), giant POMs do not exist as single ions in water. Instead, they cluster together. But scientists were still unable to understand the structures of these aggregates, even with the help of electronic microscopes.
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
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As the consequences of climate change strike across the United States, ecologists have a guiding principle about how they think plants will respond. Cold-adapted plants will survive if they move “up”—that is, as they move further north (away from the tropics) and higher in elevation (away from the warm ground).
A new survey of how tree populations have shifted over the past three decades finds that this effect is already in action. But there’s a twist: Even more than moving poleward, trees are moving west.
About three-quarters of tree species common to eastern American forests—including white oaks, sugar maples, and American hollies—have shifted their population center west since 1980. More than half of the species studied also moved northward during the same period.
These results, among the first to use empirical data to look at how climate change is shaping eastern forests, were published in Science Advances on Wednesday.
Trees, of course, don’t move themselves. But their populations can shift over time, and saplings can expand into a new region while older growth dies in another. The research team compared a tree population to a line of people stretching from Atlanta to Indianapolis: Even if everyone in the line stood still, if you added new people to the end of the line in Indiana and asked others in Georgia to leave, then the center of the line would move nonetheless.
The results are fascinating in part because they don’t immediately make sense. But the team has a hypothesis: While climate change has elevated temperatures across the eastern United States, it has significantly altered rainfall totals. The northeast has gotten a little more rain since 1980 than it did during the proceeding century, while the southeast has gotten much less rain. The Great Plains, especially in Oklahoma and Kansas, get much more than historically normal.
“Different species are responding to climate change differently. Most of the broad-leaf species—deciduous trees—are following moisture moving westward. The evergreen trees—the needle species—are primarily moving northward,” said Songlin Fei, a professor of forestry at Purdue University and one of the authors of the study.
There are a patchwork of other forces which could cause tree populations to shift west, though. Changes in land use, wildfire frequency, and the arrival of pests and blights could be shifting the population. So might the success of conservation efforts. But Fei and his colleagues argue that at least 20 percent of the change in population area is driven by changes in precipitation, which are heavily influenced by human-caused climate change.
“This is a very cool study, with results that seem to raise more questions than they can provide answers for,” said Loïc D’Orangeville, an ecologist at the Quebec Forest Research Center who was not connected to the study, in an email. “West is usually drier in the study region, so although it’s been wetter in the recent decades, it’s still drier than the East.”
“I can’t really make up [for] that moisture attractiveness for trees,” he added.
The movement of conifers and other needle trees north makes much more sense. Conifers are already more vulnerable to temperature than flowering, deciduous trees. They also already populate the boreal forest of eastern North America, so they’re well-adapted to the colder, drier conditions they will find as they expand north in the United States.
Fei and his colleagues don’t know if the westward trend will continue. We may have already seen the peak of westward movement, and northward expansion may soon outrank it. “When the result came out that trees are moving westward, our eyeballs opened wide. Like, ‘Wow, what’s going on with this?’ The results seem to show that moisture plays a much more significant role in the near-term, which is very intriguing,” he told me.
The survey draws on the U.S. Forest Service’s Forest Inventory and Analysis Program, a kind of continuously running census of the country’s tree population. The program, which stepped up in 1978 but which has been conducted in some form since the 1930s, surveys the health, density, and species mix of forested areas across the country. It examines not only the majestic, landmark tracts of untrammeled forest (like George Washington National Forest) but the humbler woods, as well: stands of trees near the highway, at the edge of housing developments, and in the middle of city parks.
“This is not a modeling exercise, there are no predictions, this is empirical data,” said Fei. “This study is looking at everything everywhere in the eastern United States.”
What concerns the team is that—if deciduous trees are moving westward while conifers move northward—important ecological communities of forests could start to break up in the east. Forests are defined as much by the mix of species, and the interaction between them, as by the simple presence of a lot of trees. If different species migrate in different directions, then communities could start to collapse.
“If you have a group of friends, and people move away to different places—some go to college in different places, and some move to Florida—the group is … probably going to fall apart,” Fei said. “We’re interested in whether this tree community is falling apart.”
“These results show contemporary proof of something we know has happened before and will happen again: that trees are highly dynamic organisms, constantly moving in response to climatic shifts like recent glaciations or other disturbances. Their actual range does not reflect conditions that are optimal for their growth,” said D’Orangeville.
Any tree’s range represents “a legacy of historical migrations and battles lost against other species or disturbances. With climate change however, their capacity to keep pace with the fast-changing climate is a major issue.”
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- Short Report
- Open Access
43 genes support the lungfish-coelacanth grouping related to the closest living relative of tetrapods with the Bayesian method under the coalescence model
© Shan et al; licensee BioMed Central Ltd. 2011
Received: 25 September 2010
Accepted: 7 March 2011
Published: 7 March 2011
Since the discovery of the "living fossil" in 1938, the coelacanth (Latimeria chalumnae) has generally been considered to be the closest living relative of the land vertebrates, and this is still the prevailing opinion in most general biology textbooks. However, the origin of tetrapods has not been resolved for decades. Three principal hypotheses (lungfish-tetrapod, coelacanth-tetrapod, or lungfish-coelacanth sister group) have been proposed.
We used the Bayesian method under the coalescence model with the latest published program (Bayesian Estimation of Species Trees, or BEST) to perform a phylogenetic analysis for seven relevant taxa and 43 nuclear protein-coding genes with the jackknife method for taxon sub-sampling. The lungfish-coelacanth sister group was consistently reconstructed with the Bayesian method under the coalescence model in 17 out of 21 taxon sets with a Bayesian posterior probability as high as 99%. Lungfish-tetrapod was only inferred from BCLS and BACLS. Neither coelacanth-tetrapod nor lungfish-coelacanth-tetrapod was recovered out of all 21 taxon sets.
Our results provide strong evidence in favor of accepting the hypothesis that lungfishes and coelacanths form a monophyletic sister-group that is the closest living relative of tetrapods. This clade was supported by high Bayesian posterior probabilities of the branch (a lungfish-coelacanth clade) and high taxon jackknife supports.
Based on comparative morphological and paleontological studies, the lungfish were historically thought to be the closest living relatives of tetrapods [4, 5], but the coelacanths were purported to have that claim [1, 6, 7] since its discovery in 1938, whereas the coelacanths and lungfish sister group (Tree III) was also proposed [8–10].
Over the last two decades, single genes and whole mitochondrial genomes have been sequenced with a view to inferring phylogenetic relationships. Lungfish as the closest relatives of tetrapods were supported by single genes [11–15] and mitochondrial whole genomes [16–19], the coelacanth as the closest living sister group of tetrapods was preferred by single genes , and coelacanth-lungfish sister group relationship was suggested by the single gene and the mitochondrial whole genome [17, 19], while an unresolved coelacanth-lungfish-tetrapod trichotomy was shown by the 12 S rRNA gene .
Recently, this question was reinvestigated. The result using 44 genes with the concatenation genome-scale approach was an unresolved trichotomy. Another from two recombination activating genes (Rag1 and Rag2) supported lungfish and not the coelacanth as the closest living relative of the tetrapods . Our previous study provided strong evidence in favor of rejecting Hypothesis 2, but weak evidence to support Hypothesis 3 based on 43 genes with three common phylogenetic methods and three genome-scale approaches [22, 23].
Although many morphological, paleontological and molecular phylogenetic studies have attempted to resolve this question, the results have so far not discovered unequivocal evidence as to whether either the coelacanth or the lungfish is the closest living relatives of tetrapods or that both lineages are equally closely related to tetrapods. Therefore, the origin of tetrapods continues to be debated and still is one of the longest standing major questions in vertebrate evolution.
BEST implements a Bayesian hierarchical model to jointly estimate gene trees and the species tree from multilocus sequences . The procedure applies the same substitution models as those used in traditional phylogenetics and coalescent theory to explain genealogical signals from species trees to gene trees and from gene trees to sequence data, forming a complete stochastic model to estimate gene trees, species trees and species divergence times simultaneously . The model is based on the assumption that gene trees are correlated due to being come from a single species tree and therefore should be estimated jointly . It provides a new approach for estimating species phylogenies within the popular Bayesian phylogenetic program MrBayes . BEST was applied to a prominent yeast phylogenomics data set and have shown that it is more efficient in estimating the species tree than concatenation is in estimating the gene tree . With simulation data, analysis of the same DNA sequences by concatenation using either Bayesian or maximum-likelihood methods reconstructed the wrong tree with high confidence, whereas the BEST analysis converged on the correct tree with high confidence .
To provide more evidence to resolve the origin of tetrapods, we used here the Bayesian method under the coalescence model with a newly published program (Bayesian Estimation of Species Trees, or BEST) for genome-scale phylogenetic analysis [24–27] and the jackknife method for taxon sub-sampling to analyze all 43 nuclear protein-encoding genes that are currently available in Genbank, having considered the results of our previous study using three other genome-scale approaches with all three commonly used phylogenetic methods together. Seven taxa include Mammal (M), Bird (B), Amphibian (A), Coelacanth (C), Lungfish (L), Ray-finned Fish (R), and Shark (S).
Materials and methods
The sequences of 43 nuclear protein-encoding genes were downloaded from GenBank through the National Center for Biotechnology Information http://www.ncbi.nlm.nih.gov/ using the program SeqMiner.pl . These 43 genes were previously analyzed using the genome-scale approach of concatenated genes; however, the sequence length of some genes was different [Additional file 1: Supplemental Table S1]. One gene (FSCN1) is omitted because some taxa lack its sequences in GenBank. In order to compare the results with the genome-scale concatenated multiple gene approach , the same seven taxa were included: Mammal, Bird, Amphibian, Coelacanth, Lungfish, Ray-finned Fish, and Shark. The species examined included human (Homo sapiens), bird (Gallus gallus), amphibian (Xenopus laevis), coelacanth (mostly Latimeria chalumnae, with a few L. menadoensis), lungfish (mostly Protopterus dolloi and P. aethiopicus) with a few Neoceratodus forsteri and Lepidosiren paradoxa), ray-finned fishes (Danio rerio), and cartilaginous fishes (represented by Scyliorhinus canicula) .
Sequences of an individual gene were aligned using ClustalX with default settings . All alignments of single genes were manually edited to exclude insertions or deletions and uncertain positions for further analysis. The BEST phylogenetic analysis software (version 1.1) with the Bayesian method under the coalescence was used for tree inference under the GTR + Γ+ I model and four simultaneous Markov chains for 20 million generations, starting with random initial trees and sampling every 2000 generations. The burnin value was set to 100. The majority rule consensus tree was generated using the remaining trees with posterior probability plotted on each node.
Taxon Jackknife Sub-sampling
We used a jackknife approach to sub-sample six, five and four taxa from seven taxa with permutation and combination. The debate over taxon sampling has not terminated. On the one hand, the accuracy was enhanced dramatically with the addition of taxa . On the other hand, adding taxa can reduce accuracy and increase the probability of distorting the tree topology . Adding characters can always increase the accuracy [30–32]. So, as many genes as possible should be included. The sequence data of 43 genes that are all currently available in GenBank were used in this study. Sequence data sets are available upon request.
The s tatistically significant difference in the Bayesian posterior probabilities for the branch of the lungfish-coelacanth or the taxon jackknife support averages between the six-, five- and four-taxon sets was analyzed by means of the chi-square test.
Tree Types, Bayesian Posterior Probability of the Branch of Lungfish-Coelacanth (tree III) or Lungfish-Tetrapods (Tree I) for 7, 6, 5 and 4-Taxon Sets, and Taxon Jackknife Supports with the Bayesian Method under the Coalescence Model
7 taxon set
6 taxon sets
5 taxon sets
4 taxon sets
Taxon jackknife support was 81.0% for tree III, 9.5% for tree I or an alternative tree other than tree I - IV, and zero for tree II and tree IV with the Bayesian method under the coalescence model for all 21 taxon sets (Table 1).
Bayesian posterior probabilities for the branch of lungfish-coelacanth were 85.0, 64.0, and 70.4% and taxon jackknife support averages were 83.3, 77.8, and 80.0% for the six-, five-, and four-taxon sets, respectively (Table 1). The chi-square test showed no significant differences among the taxon sampling sets. The results showed that taxon sampling had no significant effect on phylogenetic inference for the taxon sets.
Tree III is consistently reconstructed with the Bayesian method under the coalescence model in 17 out of 21 taxon sets with a Bayesian posterior probability as high as 99%. Tree I was inferred only from BCLS and BACLS, and two alternative trees were recovered from ACLRS and MBCLRS (Table 1). Therefore, we provide strong evidence to support Hypothesis 3, namely that coelacanths and lungfish form a monophyletic group that is the phylogenetically closest living relatives of tetrapods (Tree III). Our results agree with those of other studies in terms of the morphological, palaeontological and molecular analyses below. The coelacanth and lungfish sister group relationship was supported by the single gene and the whole mitochondrial genome , and by the nuclear 28 S ribosomal RNA gene . This relationship was also proposed in comparative morphological and paleontological studies [8–10].
Recently, an investigation using 44 genes with a concatenation genome-scale approach showed an unresolved trichotomy . Another result from two genes supported lungfish and not the coelacanth as the closest living relative of the tetrapods . In our previous study [22, 23], tree II received significantly lower support than tree I or tree III and, evidently, lower taxon jackknife probabilities with all the phylogenetic methods and genome-scale approaches. The supports for tree III were significantly higher than those for tree I for only two out of 63 events, and taxon jackknife probabilities for tree III were slightly higher than those for tree I with MP, but the differences in supports and taxon jackknife probabilities between tree III and tree I are not as obvious as those between tree II and tree III/I. Therefore, the results in our previous study provide strong evidence to reject Hypothesis 2 that coelacanth is the closest living relative of tetrapods, but only weak support for Hypothesis 3 based on phylogenetic analysis of 43 genes with those three common methods and those three genome-scale approaches yet at that time [22, 23]. Our results in this study also provide further strong evidence in favor of rejecting Hypothesis 2 because none of 21 taxon sets recovers tree II. Recently major palaeontological studies proposed that lungfishes are the closest living relatives of the tetrapods or alternatively, that coelacanths and lungfishes form a monophyletic sister group that is equally closely related to the tetrapods [33, 34]. The cause of this puzzle is the fact that the divergence of coelacanth and lungfish happened over a relatively short period within a small (20-30 millions years) window in time around 400 million years ago [3, 5]. This results in little time and opportunity for lineage-specific molecular changes to happen, yet considerable time and opportunity for multiple and parallel changes and their accumulation since the origin of these two lineages . For this challenging phylogenetic question, therefore, it was very difficult to achieve high resolution using ad hoc molecular phylogenetic methods and algorithms given that the available sequence data set of genes were currently very limited before the publication of the BEST program using the Bayesian method under the coalescence model . However, we would like to point out that the species tree inferred from gene trees using the BEST program achieves high resolution, but is not always correct for all cases. The wrong species trees, such as those of ACLRS and MBCLRS, may be recovered from gene trees (Table 1). Therefore, the jackknife method for taxon sub-sampling is recommended to obtain further statistical confidence with jackknife support values. Additionally, this approach is newly published, it is not surprising that it has not been used widely in its early stage compared with the popular concatenation approach. Some caution should be kept. However, its use is strongly encouraged based on our study and other .
This study provides strong evidence in favor of accepting Hypothesis 3, namely that the lungfish and coelacanth form a monophyletic sister group and that the sister group should be the phylogenetically closest living relatives of tetrapods. These conclusions are supported by high Bayesian posterior probabilities for the branch (a lungfish-coelacanth clade) and high taxon jackknife supports based on the genome-scale phylogenetic analysis of 43 genes using the latest program (BEST) [24, 25, 27] with the Bayesian method under the coalescence model and the jackknife method for taxon subsampling.
We thank Richard Winterbottom at the Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5 S 2C6, Canada for valuable suggestions, as well as we thank Adam Aspinall in our lab for reading this paper and providing valuable comments. This work was partially supported by the NSERC grant ORGPIN 341854, the CRC grant 950-2-3617 and the CFI grant 203617. We thank two anonymous reviewers for their good comments for improving the manuscript.
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This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. | <urn:uuid:ca193809-4ee5-4c91-919e-529df9045559> | 2.8125 | 5,201 | Academic Writing | Science & Tech. | 46.87308 | 95,630,538 |
Emperor PenguinLatin name: Aptenodytes Forsteri,
Conservsation status: near threatened (population is stable)
The Emperor is the largest of all penguins, standing as tall as four feet. Males withstand the Antarctic weather for up to two months without eating—keeping the eggs warm in a feathered pouch on their feet. Females travel up to 50 miles a day to bring food to the newly-hatched chicks.
In 50 years, the mean temperature of western Antarctica has risen nearly 3 °C—more than any other region—reducing the extent and thickness of winter ice. The Emperor Penguin is dependent on the ice for breeding, raising chicks and moulting. Less sea ice decreases zooplankton (krill) which feed on algae that grow on the underside of the ice. Krill are an important part of the food web for the Emperor and other Antarctic marine species.
Other animals at risk
Tufted Puffins are threatened by sea level rise and storm surges which destroy habitats and breeding areas. In some areas of North America warming seas are causing the fish that the Puffins feed on to migrate farther north, making it difficult for them to find adequate food. Other threats are entrapment in fishing nets, oil spills, pollution, ingestion of plastic, human disturbance of breeding colonies and introduced predators such as rats and foxes.
Climate change may affect Hawksbill Turtles in various ways because they live in different habitats at different stages of life: open ocean, beaches, lagoons and coral reefs. Rising sand temperature of nesting beaches produces more females and other abnormalities in baby turtles. Adults live primarily in coral reefs—threatened by rising ocean temperature and acidity. Since ancient times the Hawksbill has been exploited for its shell. They are also threatened from fisheries by-catch, development, and a high sensitivity to oil spills. The population has decreased by an estimated 80% in the last 100 years.
In the last 30 years the Staghorn Coral population has decreased by 80% from disease, pollution, development and damage. Climate change is increasing the risk of extinction. Corals live in symbiotic (mutually beneficial) relation with algae. The coral receives nutrients and oxygen from algae, and the algae receive nutrients and carbon dioxide from the coral. Rising sea temperature increases algae growth so oxygen levels become too high for the coral, causing "bleaching"—the coral expels the algae and dies. Higher ocean acidity contributes to bleaching and also reduces the ability of corals and other marine animals to build hard shells. Other threats from climate change are sea level rise, changes in currents and storm damage.
Clownfish live in the shallow waters of coral reefs where they have a mutually beneficial relation with a few species of sea anemone. The anenome protects the Clownfish, and the fish's swimming aerates the water around the anenome. Clownfish are unable to move long distances, and rising ocean temperature and acidity is a threat to their coral reef habitats. Increased acidity also seems to impair their ability to navigate to their home anemones. | <urn:uuid:5f339354-d3d3-4170-b71d-24242b35070b> | 4.1875 | 640 | Knowledge Article | Science & Tech. | 36.795789 | 95,630,613 |
Earth science is just that, the study of the Earth. Thorough understanding of the surface expression of textbook concepts helps geoscientists provide protection and valuable resources to society.
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The history of geology field camps dates back to the days of great explorers and naturalists like John Muir and his contemporaries. Now young men and women gear up and pack out to geologically unique locations nationwide. While traditional skill of mapping rock units and structures onto a blank topographic map still represents a foundational skill set, faculty and industry professionals are finding ways to integrate relevant technology to keep students workforce-ready.
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By: R Tobin
According to many scientists, the current destruction and extinction of numerous species will eventually lead to irreversible changes in the Earth's ecosystem. This volume is a critical evaluation of the politics of biological diversity in the USA and of state and federal policies on endangered species from the early 1960s to the present. Drawing on congressional hearings and debates, public opinion surveys, interviews with state officials and employees of the Department of the Interior, and internal documents from this and other government agencies, the author provides an analysis of the policies on endangered species and the policy relationships among the different units of government involved in policy implementation. He examines the resources that are available for the protection of endangered species and the way in which those resources are matched to the priorities. Tobin also discusses the processes by which species are classified as endangered, how these species' critical habitats are determined and protected, and the successes and failures of current recovery programmes.
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As we move toward green energy, we have a lot to consider when it comes to what kind of approach we pursue. For example, if we focus on wind turbines, much of our land would become increasingly cluttered with the turbines themselves. This has led to the research and development of offshore wind farms, which have the potential to hold bigger turbines that can generate more power. Scientists have been studying these turbines further into the ocean, and there’s a chance they could generate enough power for the world.
Wind speeds are much faster over the ocean than they are on land. Regardless of how efficient we can make them, they would theoretically generate much more power on water. These turbines max out at 1.5 watts per square meter. This has led to an increase of offshore wind farms around the world.
The United States has just scratched the surface of this renewable source. Block Island, which is off the coast of Rhode Island, became the first area to be fully powered by an offshore wind farm. Danish energy powerhouse Orsted, who used to go by Dong Energy, has been spearheading the efforts stateside with other projects along the East Coast.
While this presents a great opportunity, what if these turbines were pushed even further into the open ocean? Scientists have been studying whether or not they could take advantage of the additional wind power in these locations. By adding those, could that affect the wind overseas?
"Are the winds so fast just because there is nothing out there to slow them down?” Ken Caldeira, a scientist at the Carnegie Institution for Science, said to Science Daily. “Will sticking giant wind farms out there just slow down the winds so much that it is no better than over land? ...The real question is can the atmosphere over the ocean move more energy downward than the atmosphere over land is able to?"
Based on their studies with potential farms in the North Atlantic Ocean, winds wouldn’t slow down in the open ocean. In fact, they wouldn’t suffer from the limitations of both land and offshore wind turbines. This is due to the heat that comes off of the ocean during the winter season. As expected, this would change during the summer with less energy being generated.
According to EcoWatch, winds over the ocean would be at least 70 percent higher than on land. Up to 13.5 kms per second can be achieved in the Southern Hemisphere. Hypothetically, up to 80 watts per square meter could be generated, but we can’t harvest near that amount as usable electricity due to turbine drag. However, at least three times the amount of energy that can be generated on land could be obtained.
There’s a number of questions that still remain as research continues. Maintenance is already tough on offshore wind farms, and that would be a bigger obstacle in the open ocean. How will this energy be delivered around the world if it can be generated at that scale? As always, technological improvements and decreasing costs will likely make this a viable option in the future.
Sweden's aggressive target of generating over 40 terawatt-hours of renewable energy by 2030 could be reached nearly a decade early. A massive amount of wind power projects could hit a snag in market value with subsidies, but SWEA could push to close those up by the end of the year.
It's challenging and laborious to detect this bacteria that decimates bee populations, so an apiary inspector trained a dog to do it. They're amazing.
New technologies means that instead of sucking power off the energy grid, buildings can feed back into it, powering other buildings and even cars.
A sixth-grader in Massachusetts has begun developing a robot that's able to detect microplastics in our ocean after wanting to make a difference at the Boston Harbor. Her ultimate goal is to create a way to also pick up trash and cut costs in the process. | <urn:uuid:cc3f1aea-d456-491a-8263-4c24686a372e> | 3.875 | 795 | News Article | Science & Tech. | 55.364861 | 95,630,683 |
New research by biologists at the University of Pennsylvania School of Veterinary Medicine has now identified one way the body does exactly that. This protective role is fulfilled in part by a class of small RNA molecules called pachytene piwi-interacting RNAs, or piRNAs.
Without them, germ-cell development in males comes to a halt. Because these play such an important role in allowing sperm to develop normally, the research indicates that defects in these molecules or the molecules with which they interact may be responsible for some cases of male infertility.
Jeremy Wang, an associate professor of developmental biology and director of the Center for Animal Transgenesis and Germ Cell Research at Penn Vet, and Ke Zheng, a postdoctoral researcher in Wang's lab, authored the study, which appears in PLOS Genetics.
Scientists know of 8 million different piRNAs in existence; they are the most abundant type of small non-coding RNA. The molecule piRNA gets its name because it forms complexes with piwi proteins. Earlier work had indicated that these piwi-piRNA complexes suppress the activity of transposable elements or "jumping genes," which are stretches of DNA that can change position and cause potentially damaging genetic mutations. These sequences are also known as transposons.
"There are about 50 human diseases caused by transposable elements, so it's important for the body to have a way to try to repress them," Wang said.
This transposon-suppressing activity had been confirmed in a group of piRNAs called pre-pachytene piRNAs, which are expressed before meiosis, the unique process by which germ cells divide. But Zheng and Wang wanted to investigate if a separate group of piRNAs that emerge during meiosis, called pachytene piRNAs, were also required for "silencing" transposons.
Working in male mice, the researchers manipulated an enzyme called MOV10L1, which is known to interact with piwi proteins and is believed to help produce piRNA molecules. They created a mutant mouse in which they could selectively inactivate MOV10L1 at specific stages before, during and after meiosis. The mice that lost the function of MOV10L1 before or at the pachytene stage of meiosis were sterile. When Zheng and Wang examined their germ cells more closely, they found that spermatogenesis had apparently come to a halt at the post-meiotic stage: Early stages of the germ cells were present, but the mice completely lacked mature sperm.
Further experiments allowed Zheng and Wang to pinpoint that MOV10L1 was playing a critical role at the pachytene stage. MOV10L1 mutants lacked pachytene piRNAs, but their levels of pre-pachytene piRNAs were unaffected, as the mutation was "turned on" after they had already been produced.
The researchers also found that, in the MOV10L1 mutants, piwi proteins congregated together along with mitochondria, suggesting that mitochondria may be involved in the generation or organization of pachytene piRNAs. Furthermore, the spermatids, or early-stage sperm, of the mutants had severe DNA damage. While the researchers suspected that the damage may have been caused because of transposons that had been freed from repression in the absence of piRNAs, they actually found that two common transposable elements were not de-repressed in the mutants. They also found a build-up of pachytene piRNA precursors in the testes of the mutants. Their findings raise the possibility that there is another mechanism by which damage occurs.
"It could be the accumulation of precursor molecules is causing some of the damage," Wang said.
This new function for MOV10L1, in playing an essential role in producing pachytene piRNAs, gives researchers a greater understanding of germ-cell development.
"This is the first time we've shown that pachtyene piRNA is required for maintaining genome integrity in the post-meiotic germ cells," Wang said. "It turns out that MOV10L1 is a master regulator of the piRNA pathway and is required for the production of all piRNAs, both pre-pachytene and pachytene."
Any disruptions to this "master regulator" role, therefore, could lead to problems.
"I think we're just beginning to appreciate the significance of this pathway," Wang said. "Mutations at various points in the pathway could lead to infertility."
This research was supported by the National Institutes of Health's National Institute of Child Health and Human Development.
Katherine Unger Baillie | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Materials Sciences
19.07.2018 | Earth Sciences
19.07.2018 | Life Sciences | <urn:uuid:f39171e7-be46-42df-bd3f-9e6edb66e442> | 3.46875 | 1,614 | Content Listing | Science & Tech. | 36.646078 | 95,630,684 |
On Friday the 30th, during the XLII international winter meeting on nuclear physics at Bormio, the first results will be announced of Finuda experiment (Nuclear Physics at Daphne), settled in Frascati at Infn National Laboratories.
Planned and made operating by a group of about forty physicists from Universities and Infn Sites of Bari, Brescia, Frascati, Pavia, Torino and Trieste, Finuda is devoted to the study of hypernuclei: nuclei composed by three different kinds of particles rather then two (protons and neutrons) as in ordinary nuclei.
The first stage of the experiment started on October the15th and the data obtained up to now promise to be the most relevant in the study of hypernuclei since their discovery occurred in 1953 thanks to the Polish physicists Marian Danysz e Jerzy Pnieswski. “The study of hypernuclei opens a favoured window to understand some aspects of the strong force and the weak force which, with electromagnetic and gravitational forces, complete the whole of the four fundamental forces in nature” says Sergio Bertolucci, director of the National Laboratories of Frascati.
Barbara Gallavotti | alfa
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:51f625dc-033a-4166-a535-023e6997faff> | 2.890625 | 831 | Content Listing | Science & Tech. | 34.440773 | 95,630,696 |
"Making these measurements possible is the platform on which the instruments are flying," said Paul Newman, the deputy principal investigator of NASA's Hurricane and Severe Storm Sentinel (HS3), managed by NASA's Goddard Space Flight Center in Greenbelt, Md. HS3 will use NASA's unmanned Global Hawks, which are capable of flying at altitudes greater than 60,000 feet with flight durations of up to 28 hours — capabilities that increase the amount of data scientists can collect. "It's a brand-new way to do science," Newman said.
The High Altitude Monolithic Microwave integrated Circuit (MMIC) Sounding Radiometer (HAMSR) is a microwave atmospheric sounder developed by JPL under the NASA Instrument Incubator Program. Credit: NASA JPL
Photo of the new purple CPL with the Global Hawk. Credit: NASA
The month-long HS3 mission, which began in early September, is actually a more robust follow-on to NASA's Genesis and Rapid Intensification Processes (GRIP) experiment that scientists executed in 2010. Often referred to as "GRIP on steroids," HS3 is currently deploying one instrument-laden Global Hawk from the NASA Wallops Flight Facility on Virginia's Eastern Shore to look at the environment of tropical storms. In 2013 and 2014, a second Global Hawk will be added that will focus on getting detailed measurements of the inner core of hurricanes.
Without this new aircraft, developed originally for the U.S. Air Force to gather intelligence and surveillance data, the team says the mission wouldn't be possible.
The Global Hawk's ability to fly for a much longer period of time than manned aircraft will allow it to obtain previously difficult-to-get data. Scientists hope to use that data to gain new insights into how tropical storms form, and more importantly, how they intensify into major Atlantic hurricanes — information that forecasters need to make better storm predictions, save lives, and ultimately prevent costly coastal evacuations if a storm doesn't warrant them.
"Because you can get to Africa from Wallops, we'll be able to study developing systems way out into the Atlantic," Newman explained. "Normal planes, which can fly for no more than about 10 hours, often miss the points where storms intensify," added Gerry Heymsfield, a Goddard scientist who used NASA Research and Development funding to create one of the mission's six instruments, the High-altitude Imaging Wind and Rain Airborne Profiler (HIWRAP). "With the Global Hawks, we have a much higher chance of capturing these events. Furthermore, we can sit on targets for a long time."
Just as important as the aircraft are the new or enhanced instruments designed to gather critical wind, temperature, humidity, and aerosol measurements in the environment surrounding the storm and the rain and wind patterns occurring inside their inner cores, they added. "The instruments bring it all together," Newman said. "We didn't have these instruments 10 years ago."
The Global Hawk currently on deployment at Wallops is known as the "environmental" aircraft because it samples the environment in which hurricanes are embedded. It carries three instruments.
A Goddard-provided laser system called the Cloud Physics Lidar (CPL) is located in the nose. CPL measures cloud structures and aerosols, such as dust, sea salt particles, and smoke particles, by bouncing laser light off these elements. An infrared instrument called the Scanning High-resolution Interferometer Sounder (S-HIS), provided by the University of Wisconsin in Madison, sits in the belly of the aircraft. It measures the vertical profile of temperature and water vapor.
At the tail end is a dropsonde system provided by the National Center for Atmospheric Research and the National Oceanic and Atmospheric Administration. This system consists of 88 paper-towel-roll-sized tubes that are ejected much like a soda can in a vending machine. As the sensor drops, a parachute slows its descent, allowing the sensor to drift down through the storm while measuring winds, temperature, pressure, and humidity.
In 2013 and 2014, working in tandem with its environmental counterpart, will be a second Global Hawk, known as the "over-storm" aircraft. It will sample the internal structure of hurricanes. It, too, will carry three instruments.
Heymsfield's HIWRAP, for example, will be situated in the belly of the Global Hawk and will be responsible for sampling the cores of hurricanes. Similar to a ground radar system, but pointed downward, HIWRAP measures rain structure and winds, providing a three-dimensional view of these conditions.
Also onboard this craft will be a microwave system called the High-Altitude MMIC Sounding Radiometer (HAMSR), created by NASA's Jet Propulsion Laboratory in Pasadena, Calif. Located in the aircraft's nose, this instrument uses microwave wavelengths to measure temperature, water vapor, and precipitation from the top of the storm to the surface.
At the other end of the aircraft in the tail section will be the Hurricane Imaging Radiometer (HIRAD) provided by NASA's Marshall Space Flight Center in Huntsville, Ala. This microwave instrument measures surface wind speeds and rain rates in an unusual way. It collects this data by measuring the amount of "foaminess" in ocean waters. According to Newman, the amount of foaminess is proportional to wind speeds at the surface.
Although all six instruments measure different conditions, they share one important characteristic: all operate autonomously and deliver data to scientists in real-time — another scientific advance. In the past, aircraft instruments, which often required the presence of a scientist to operate them, would record captured data. Only after the aircraft landed could scientists begin evaluating what they had collected.
With the Global Hawk, however, the data are transmitted to the ground in real-time. Should conditions warrant, the science team can direct the pilot, who flies the aircraft from a computer console on the ground, to change course or tweak the pre-programmed flight path in some way to maximize or improve the data they are gathering. "With the Global Hawk and these instruments, we can make better decisions," Heymsfield added.
The five-year mission will continue through 2014, at which time the team hopes to have dramatically improved their understanding of how storms intensify. "The insights we get will benefit forecasters," Newman said. "What we hope to do is take this technique and make it part of the operational forecast infrastructure."
The HS3 mission is supported by several NASA facilities including Wallops, Goddard, NASA's Dryden Flight Research Center at Edwards Air Force Base, Calif., Ames Research Center, Moffett Field, Calif.; Marshall Space Flight Center, Huntsville, Ala.; and the Jet Propulsion Laboratory, Pasadena, Calif. In addition, the mission also involves collaborations with various partners from government agencies and academia.
HS3 is an Earth Venture mission funded by NASA's Science Mission Directorate in Washington. Earth Venture missions are managed by NASA's Earth System Science Pathfinder Program at NASA's Langley Research Center, Hampton, Va. The HS3 Project itself is managed by the Earth Science Project Office at NASA's Ames Research Center.For more information about the NASA GRIP mission, visit:
Robert Gutro | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
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Filters: Tags: Baseline 5-Data (X)325 results (11ms)
During the period 1970-2000, substantial efforts were made to document the distribution and number of Trumpeter Swans (Cygnus buccinator) in western Canada. Breeding surveys have expanded from covering less than 20,000 km2 in the Grande Prairie region of Alberta to cover 780,000 km2, perhaps one-third of northwestern Canada. Aerial surveys involving total or partial counts have been used in most areas. Since 1995, sample-based surveys have been used in Yukon Territory and extreme northern British Columbia. Between 1970 and 2000, breeding surveys have documented a dramatic increase in both breeding distribution and numbers in western Canada (100 to more than 3,700). Winter surveys in British Columbia have corroborated...
Ecological effects of invasive European bird cherry (Prunus padus) on salmonid food webs in Anchorage, Alaska streams
Invasive species are a concern worldwide as they can displace native species, reduce biodiversity, and disrupt ecological processes. European bird cherry (Prunus padus) (EBC) is an invasive ornamental tree that is rapidly spreading and possibly displacing native trees along streams in parts of urban Alaska. The objectives of this study were to: 1) map the current distribution of EBC along two Anchorage streams, Campbell and Chester creeks, and 2) determine the effects of EBC on selected ecological processes linked to stream salmon food webs. Data from the 2009 and 2010 field seasons showed: EBC was widely distributed along Campbell and Chester creeks; EBC leaf litter in streams broke down rapidly and supported similar...
Range overlap and individual movements during breeding season influence genetic relationships of caribou herds in south-central Alaska
North American caribou (Rangifer tarandus) herds commonly exhibit little nuclear genetic differentiation among adjacent herds, although available evidence supports strong demographic separation, even for herds with seasonal range overlap. During 1997–2003, we studied the Mentasta and Nelchina caribou herds in south-central Alaska using radiotelemetry to determine individual movements and range overlap during the breeding season, and nuclear and mitochondrial DNA (mtDNA) markers to assess levels of genetic differentiation. Although the herds were considered discrete because females calved in separate regions, individual movements and breeding-range overlap in some years provided opportunity for male-mediated gene...
River discharge predicts spatial distributions of beluga whales in the Upper Cook Inlet, Alaska, during early summer
Moose, Caribou, and Grizzly Bear Distribution in Relation to Road Traffic in Denali National Park, Alaska
Studies moose or Alces alces, caribou or Rangifer tarandus and grizzly bear or Ursus arctos distribution in relation to road traffic in Denali National Park, Alaska. Development of wildlife monitoring system using 19 landscape level viewsheds stratified into four sections based on decreasing traffic along the road corridor; Absence of traffic avoidance patterns for caribou and grizzly bears.
Population characteristics, space use and habitat selection of two non-migratory caribou herds in central Alaska, 1994 - 2009
Nutritional restrictions in winter may reduce the availability of protein for reproduction and survival in northern ungulates. We refined a technique that uses recently voided excreta on snow to assess protein status in wild caribou (Rangifer tarandus) in late winter. Our study was the first application of this non-invasive, isotopic approach to assess protein status of wild caribou by determining dietary and endogenous contributions of nitrogen (N) to urinary urea. We used isotopic ratios of N (?15N) in urine and fecal samples to estimate the proportion of urea N derived from body N (p-UN) in pregnant, adult females of the Chisana Herd, a small population that ranged across the Alaska-Yukon border. We took advantage...
Diversity of nitrogen isotopes and protein status in caribou: implications for monitoring northern ungulates
Fishery Management Report for Sport Fisheries in the Arctic-Yukon- Kuskokwim Management Area, 1999-2000
Report is divided into three sections. In Section I, an overview of the Arctic-Yukon-Kuskokwim Management Area is provided, including a description of the area and subareas, Board of Fish activities, and management information and activities. In Section II, effort and harvest results are presented. In Section III, more detailed summaries of major fisheries and activities are provided
Caribou Hunters and Researchers at the Co-management Interface: Emergent Dilemmas and the Dynamics of Legitimacy in Power Sharing
A content analysis of PCMB meeting minutes from its first meeting to 1993 reveals a repeated pattern of communication in which Native hunters pose questions about the need for caribou research requiring the use of aircraft and collars and the handling of animals, and a response by agency managers to inform community residents about the value of collars in science and/or demonstrating their application. Never discussed openly at PCMB meetings was what the Gwich'in regard as a negotiated order of power-sharing arrangement between Gwich'in and caribou, established in the time before there was time, nunh ttrotsit ultsui gwuno (when the earth was first made), when caribou were people and people were caribou. As told...
at publisher site.] | <urn:uuid:40136841-8046-4888-b33c-0cd1fe7caaeb> | 2.9375 | 1,132 | Content Listing | Science & Tech. | 20.619093 | 95,630,725 |
There's no debating evolution, but a debate remains among biologists over how it actually works. Is evolution deterministic in that its outcomes could not have been otherwise, or is it more random? Harvard biologist Jonathan Losos defends the view that evolution is not deterministic, that takes many different pathways to endpoints that are historically contingent. Take for instance the island of New Zealand which has been geographically isolated from Australia for 80 million years. If evolution were deterministic, we'd expect to see dinosaurs just as they had once existed on Earth, but we see kiwis and moas instead. Losos says that has important implications for life may look like on alien worlds, i.e. don't expect any spacefaring T. rexes. Learn more about evolution from his book, Improbable Destinies: Fate, Chance, and the Future of Evolution. | <urn:uuid:9952a420-dc16-4e87-af3f-92b3d698ab90> | 3.1875 | 174 | Truncated | Science & Tech. | 38.133694 | 95,630,729 |
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Thunderstorms and rain engulf central and southern Europe
Thunderstorm over Berlin
Rain and thunderstorms have hit Europe in full force this spring. May was wetter than average across much of southern Europe. In France, Italy and Greece these conditions damaged agricultural crops.
In Europe as a whole, May was the warmest on record - fully 2.5°C above the average. Temperatures were unusually high across Scandinavia and the northern and central part of the continent. This was because a persistent high-pressure system created settled weather conditions, allowing high temperatures to develop.
This fostered thunderous conditions everywhere in Europe, even so the northern part was relatively dry when considering the total rainfall of the month. During those severe thunderstorms, hundreds of thousands of lightning strikes took place.
On 13 May, more than 30 mm of rain fell within one hour in some places because the atmospheric conditions meant the area of precipitation only moved very slowly. At Winterberg in Germany, a centimetre-deep layer of hail was reported. Streets and basements were flooded, and in Ostfriesland, Germany, a music festival was cancelled. Elsewhere, the A30 between Hannover and Amsterdam was completely closed for a short time due to floods.
To understand what happened during May, the Copernicus Climate Change Service implemented by European Centre for Medium-Range Weather Forecasts (ECMWF) looked back at May’s unusually large number of thunderstorms using the ERA5 dataset. ERA5 provides hourly estimates of atmospheric, land and oceanic climate variables. The one of interest here is called CAPE (convective available potential energy), measured in units of Joules per kilogram.
CAPE is commonly used as a measure of the potential for convection to develop in the atmosphere. When convection occurs, large parcels of air move upwards carrying heat and moisture, which in turn can lead to thunderstorms. Values of CAPE above 100 J/kg indicate that convection is possible. If rainfall occurs in a situation like this, it is thus likely to come from clouds that develop more or less locally as the air parcel travels upwards, rather than coming from rainclouds brought in on the wind from far afield.
When CAPE tops 1000 J/kg, it is often associated with the strong vertical ascent of air and severe thunderstorms. Although such strong convection is not confined to any particular value of CAPE and can occur at lower values, 1000 J/kg can be considered a rough threshold for the potential outbreak of severe thunderstorms.
Hence, although CAPE is not a measure of how many thunderstorms there were, it can give a good indication of where there was the possibility of thunderstorms developing.
The left image shows the number of lightning strikes during 13 May 2018 (Source: UK Met Office ATDnet lightning densities), the right image shows the maximum over-land value for CAPE (J/kg) for the same day, based on data from ERA5. The highest values of CAPE largely correspond to the areas that saw a large number of lightning strikes. (Credit: Copernicus Climate Change Service /ECMWF)
By analysing the average CAPE for the month, researchers find that CAPE was higher than 100 for many more days than is usual at this time of year in most of continental Europe. In most of central Europe and the regions around the Adriatic coast, the potential for thunderstorms (as indicated by CAPE values greater than 1000) was also larger than the average for May.
The graph shows the number of days in May 2018 with maximum daily CAPE values above 1000J/kg, compared to the average number of such days during 1986-2015. (Data source: ERA5, Credit: Copernicus Climate Change Service /ECMWF).
As well as being a hot month for Europe, May temperatures were above average almost everywhere around the globe. The only major exceptions included Greenland and northern Canada. Furthermore, sea ice cover in both the Arctic and the Antarctic was much below average.
Note on ERA5: The data shown here is partly based on pre-release data for ERA5. Values might change slightly in the final consolidated dataset. The climatological period (1986-2015) is based on the currently earliest available 30-year time-series for ERA5. Consolidated ERA5 data is currently available for 2008- 2017 in the Climate Data Store. | <urn:uuid:c228b339-d9ce-4901-87cc-c4570fe71ad2> | 3.328125 | 912 | Knowledge Article | Science & Tech. | 37.214109 | 95,630,740 |
Taking the pulse of Mars via dating of a plume-fed volcano
MetadataShow full item record
Mars hosts the solar system's largest volcanoes. Although their size and impact crater density indicate continued activity over billions of years, their formation rates are poorly understood. Here we quantify the growth rate of a Martian volcano by 40Ar/39Ar and cosmogenic exposure dating of six nakhlites, meteorites that were ejected from Mars by a single impact event at 10.7 ± 0.8 Ma (2σ). We find that the nakhlites sample a layered volcanic sequence with at least four discrete eruptive events spanning 93 ± 12 Ma (1416 ± 7 Ma to 1322 ± 10 Ma (2σ)). A non-radiogenic trapped 40Ar/36Ar value of 1511 ± 74 (2σ) provides a precise and robust constraint for the mid-Amazonian Martian atmosphere. Our data show that the nakhlite-source volcano grew at a rate of ca. 0.4-0.7 m Ma-1-three orders of magnitude slower than comparable volcanoes on Earth, and necessitating that Mars was far more volcanically active earlier in its history.
Cohen , B E , Mark , D F , Cassata , W S , Lee , M R , Tomkinson , T & Smith , C L 2017 , ' Taking the pulse of Mars via dating of a plume-fed volcano ' Nature Communications , vol 8 , 640 . DOI: 10.1038/s41467-017-00513-8
© The Author(s) 2017. Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
DescriptionThis work was funded by the Science and Technology Facilities Council (grants ST/H002472/1, ST/H002960/1 and ST/K000918/1 to D.F.M. and M.R.L.) and the NASA Mars Fundamental Research Program (grant NNH14AX56I to W.S.C.). Portions of this work were performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated. | <urn:uuid:6f8adf13-37aa-4269-bb57-f0813aefe0a4> | 2.859375 | 640 | Academic Writing | Science & Tech. | 58.425 | 95,630,743 |
According to reports, the satellite, which is aimed at finding far-away planets that could potentially support life, will be launched at 6:32 pm US Eastern Daylight Time (EDT) from the Cape Canaveral Air Force Station.
NASA's newest planet-hunting spacecraft will have to wait another couple of days before lifting off.
2 April space, the company performed a successful launch of the Falcon 9 rocket with the spacecraft Dragon, who managed to deliver to the ISS the 2.6 MT of cargo.
NASA is all set to launch its next hunt for planets outside our solar system as preparations get underway for the launch of the TESS satellite, which will be carried into space in a SpaceX Falcon 9 rocket on Tuesday morning. Though Kepler Space Telescope has been doing the same job for years, the new satellite will advance its work and look for Earth-like planetary bodies orbiting some 200,000 brightest stars close to our sun.
"But since then, we have found thousands of planets orbiting others stars and we think all the stars in our galaxy must have their own family of planets".
United Kingdom and UK are warning that Russian Federation has been hacking routers worldwide
What no-one is quite sure of is whether this creates a deterrent a bit like mutually assured nuclear destruction in the Cold War. In a joint statement, said they said the cyber-attack had been aimed not just at the United Kingdom and USA but globally.
NASA says TESS could help answer the age-old question: Are we alone in the universe?
An artist's rendition of NASA's Transiting Exoplanet Survey Satellite, or TESS.
TESS, with its four advanced cameras, will scan an area that is 350 times larger, comprising 85 percent of the sky in the first two years alone.
The SpaceX rocket launch scheduled for Monday evening has been delayed.
"Tess will find small planets, rocky planets that might have atmospheres and features that may be conducive to life", Buzasi said. | <urn:uuid:ebc17903-1caf-4273-a0b4-163624bb670c> | 2.8125 | 405 | Content Listing | Science & Tech. | 49.492898 | 95,630,751 |
Seeing Cell to Cell Differences
News Apr 05, 2016
Every cell in the body has two genomes, one from the mother and one from the father. Until now, researchers have lacked the tools to examine -- in a single cell --the exact readout from each genome to make RNA. Using a new technology that allows researchers to do just that, an interdisciplinary University of Pennsylvania team examined a rare disease in which these two genomes are expressed differently throughout the body, even sometimes in the same organ. They found that at the single-cell level gene expression was highly variable and quite different than expected, which is now shedding light on the molecular causes of rare diseases and perhaps the complex nature of tumors.
“This is a great example of cross-school collaboration,” said co-senior author Marisa Bartolomei, PhD, a professor of Cell and Developmental Biology in the Perelman School of Medicine. Her colleagues are co-first author Jennifer M. Kalish, MD, PhD, an expert in rare growth disorders from The Children’s Hospital of Philadelphia, and co-first author Paul Ginart, an MD/PhD candidate, and co-senior author Arjun Raj, PhD, both from the School of Engineering and Applied Science at Penn, who devised the technology to image single genes in individual cells.
“With this new technique, we can now see which cells express which genome,” Bartolomei said.
Silence of the Genes
For most genes, people inherit two copies, one maternal and one paternal. However, in the case of a phenomenon called imprinting, offspring inherit only one working copy of a gene, and depending on its parental origin, expression of the gene is controlled by an added methyl group during egg or sperm formation to physically tighten DNA so it cannot be read to make RNA and ultimately protein.
A small number of genes are imprinted but are critical to normal development. Imprinted genes are normally turned on from either the maternal chromosome or the paternal chromosome, but not both. In human imprinting disorders, imprinted genes are either abnormally turned on for both the maternal and paternal genomes, or abnormally turned off from both genomes. Abnormal expression can be linked to genetic mutations and mistakes in the placement of the methyl group (a function of epigenetics).
Variability from cell to cell in which genes are expressed in the same organ may help explain why many diseases show a “mosaic” pattern, with different parts of the body exhibiting different degrees of disease. This hodge-podge can happen because of errors in imprinting.
Defects in imprinting can lead to inappropriate expression of the normally silenced version of the gene, but it remains unclear whether every cell in a given organ expresses the abnormal version. “If this were the case, it would have profound implications for human imprinting disorders,” Kalish said.
Help from the Rare
Imprinting disorders are rare. Kalish works with two: Russell-Silver syndrome, an under growth disorder occurring in approximately 1 out of 50,000 to out of 100,000 births, with symptoms of small stature and limb, body, or facial asymmetry. The syndrome involves under-methylation of two genes, H19 and IGF2.H19 encodes a non-coding RNA that limits growth whereas IGF2 is a growth factor. In 50 percent of cases, Russell-Silver syndrome is associated with an imprinting error on chromosome 11 in which the person receives two copies of the imprinting mark from the mother rather than one from each parent. Russell-Silver children have too much of the do-not-grow signal (H19) and too little of the grow signal (IGF2). The other imprinting disorder is Beckwith-Wiedemann syndrome, an overgrowth disorder usually present at birth, characterized by an increased risk of childhood cancer and such congenital features as a large tongue, large birth weight, and limb, body, organ, and facial asymmetry.
These syndromes display a range of symptoms, which happens because some cells in a given organ express maternal genes while others express paternal genes. “But the mom genes are the ones that limit growth of cells,” Kalish said. “This means that the mosaic pattern is really a mix of normal cells and abnormal cells -- with a disrupted balance between mom’s do-not-grow signals and dad’s grow signals, in the same tissue. This is what accounts for an enlarged or too-small organ in the same person.” In some cases, patients may even have differently sized pairs of kidneys.
Using mice, the team compared cell genomes in normal mice versus Russell-Silver syndrome mice. At the cell population level, they asked which individual cells have correct maternal imprinting and which cells have abnormal maternal imprinting for the H19 gene. In Russell-Silver mice both maternal and paternal H19 is expressed.
Using Raj’s new technology, they developed a molecular probe to detect a single nucleotide change in the RNA expressed in mom’s versus dad’s genomes to show which is expressed cell by cell. This method measured gene-variant specific expression in single cells. In the mouse model of Russell-Silver syndrome, they found that some cells had RNA from both the maternal and paternal version (abnormal—as seen in Russell-Silver patients) while other cells had only the maternal RNA (normal).
“We showed that mutant mouse embryo fibroblast cells are comprised of two subpopulations: those expressing both maternal and paternal H19 versions [abnormal] and those expressing only the maternal copy [normal],” Bartolomei said. “Only in the latter normal cell population is Igf2 expression detected.”
In the Russell-Silver mice, all cells had the same genetic change but not all cells had the same DNA methylation pattern, explaining the mosaic arrangement of gene expression by epigenetics -- the normal silencing of a version of a gene by the added methyl group during egg or sperm formation.
The two mutant subpopulations of cells exhibited distinct methylation patterns at the imprinting control region of their respective genomes. The cells that expressed H19 from just the maternal genome had the correct DNA methylation pattern while the cells that expressed H19 from both maternal and parental genomes exhibited a loss of H19 DNA methylation. Importantly, they also observed the same two subpopulations are also present within mouse heart tissue, showing the same defect in a living whole mouse.
“This is the first time that epigenetic mosaicism has been demonstrated at a single cell level,” Bartolomei said. “What this means is that epigenetics -- the balance of tightening or loosening of DNA to control which genes are expressed when -- is the driver of mosaicism at the cell population level. Our results establish that imprinting disorders can display striking single-cell heterogeneity and suggest that such heterogeneity may underlie epigenetic mosaicism in human imprinting disorders,” Bartolomei said.
“The epigenetic mosaicism shown in this work explains the spectrum of clinical features we see in our patients -- it all makes sense,” Kalish said. “Now we know what is going on.”
Hay Fever Risk Genes Overlap with Autoimmune DiseaseNews
In a large international study involving almost 900,000 participants, researchers from the University of Copenhagen and COPSAC have found new risk genes for hay fever. It is the largest genetic study so far on this type of allergy, which affects millions of people around the world.READ MORE
Hidden Signals in RNAs Regulate Protein SynthesisNews
Scientists have long known that RNA encodes instructions to make proteins. In a new study published in Nature, scientists describe how the protein-making machinery identifies alternative initiation sites from which to start protein synthesis.READ MORE | <urn:uuid:21330bed-8375-42d7-a239-e493000bf7fa> | 3.484375 | 1,633 | News Article | Science & Tech. | 32.885712 | 95,630,778 |
1 year ago
Academy Award-winning actor Leonardo DiCaprio called on his massive Twitter following this week to help bring attention to and help conserve the most endangered marine mammal in the world.
The star’s plea prompted a response from the Mexican president and forcing the mammal to trend on the social platform.
— Leonardo DiCaprio (@LeoDiCaprio) May 12, 2017
“With fewer than 30 vaquita left, the time to act is now. #SavetheVaquita,” DiCaprio tweeted.
Mexican President Enrique Peña Nieto didn’t address DiCaprio directly, but responded to the issue, writing: “Mexico’s government is making a major effort, doing what should have been done decades ago to save the Laquita Marina.”
Mexico’s government is making a major effort, doing what should have been done decades ago to save the Vaquita Marina.
— Enrique Peña Nieto (@EPN) May 12, 2017
The dark-eyed vaquita porpoise is estimated to go completely extinct by the middle of 2018, the BBC reports, their population having plummeted by 90 percent in the last six years.
— Humanity Strong ™ (@HumanityStrong) May 16, 2017
Many of the porpoises are often accidentally killed in gillnets, according to the BBC, which were banned for two years in 2015. Conservationists and researchers reportedly hope the Mexican government will extend and strengthen the existing ban in light of the species’ state of critical endangerment.
The rare mammal lives exclusively in the Gulf of California, a world heritage site situated between the Mexican mainland and the Baja peninsula. The waters are home to both a massive area of biodiversity and half of Mexico’s total fisheries production. | <urn:uuid:26600ab8-1cad-43e2-8793-f139f2b6b5fe> | 2.59375 | 377 | News Article | Science & Tech. | 33.29518 | 95,630,784 |
Displaying results 1 - 20 of 60 matches (0.02 seconds)
shows that the HKH remains energy-poor, with more than 80% of rural households still reliant on traditional solid biomass fuel for cooking and heating. This is causing enormous damage to the environment, triggering widespread harm to human
Energy efficiency studies have traditionally focused on households or industries. Recent studies by the World Bank and the US Agency for International Development (USAID)’s South Asia Regional Initiative for Energy Integration (SARI/EI) programme
The region has high hydropower potential, but the changing climate and likely changes in the hydrological regime may pose a risk to future hydropower development. The changing probabilities and magnitudes of extreme events can place an additional
Urbanization is leading to water scarcity for millions of people in the growing cities of the Hindu Kush Himalayas. The massive river systems that supply the water for a range of daily needs, from drinking water to electricity generation, can’t
The SAARC Chamber of Commerce and Industry (SAARC CCI), an apex body of private sector in South Asia, realises that climate change triggered water scarcity and natural disasters may pose serious threats for human life and livelihoods...
Resilient mountain village
The World Water Day provides us an opportunity to join our friends and colleagues from the Hindu Kush Himalayas (HKH) and the rest of the world in creating awareness about the importance of water for human and ecosystem wellbeing towards achieving
Many big rivers like the Indus, Ganges, and Brahmaputra originate from the snow and glacier covered high mountains, and have abundant seasonal and annual water supply. Despite this, mountain people living on the ridges and hill slopes have limited
Water resources assessment and monitoring
Second Workshop on HKH Monitoring and Assessment Programme (HIMAP)
The Himalayan region faces a greater uncertainty of earthquakes and question come to peoples’ mind on when, where, and how big. Science has not developed enough to predict earthquakes and even California in US is still struggling to develop
Dr Shobhakar Dhakal is an Associate Professor at the Asian Institute of Technology in Thailand. His areas of expertize are in energy and climate change mitigation policies and modeling and on urbanization/cities and climate change.
Forum reveals new possibilities for water induced disaster management in the Koshi basin
International Expert Consultation on Mountains and Climate Change
Quest to unravel the cause of the Seti flash flood, 5 May 2012 | <urn:uuid:8842ae63-0fe1-435a-8bb4-0ce84cf29982> | 2.765625 | 511 | Content Listing | Science & Tech. | 13.514818 | 95,630,814 |
posted by Mark Russel
1. a is directly proportional to b.If a=15,then b=9
2. m varies directly as n.If n=2/3,then m=1/4
3. T varies as the square root of L. If L=81,then T=10
4.r varies directly as the square of t. If t=16,then r=6.
5. y varies as the cube foot of x. If x=27,then y=2.
6. y is directly proportional to x. If y=15 when x=4,find y when x=5.
7. m varies directly as n. If m= -6 when n=2,find m when n=-3
8. The square of x varies directly as the cube of y. When x=2,y=4,find y when x=8
What do you want for #1 - 5 ?
Are you finding the constant of variation or what?
I will do one of them, #4
r varies directly as the square of t. ---> r = kt^2
when t=16, r=6
6 = k(16)^2
6 = 256k
k = 6/256 = 3/128
so r = (3/128)t^2
The square of x varies directly as the cube of y. ---> x^2 = ky^3
when x=2, y=4
4 = k(64)
k = 4/64 = 1/16
so x^2 = (1/16)y^3
when x = 8
64 = (1/16)y^3
y^3 = 1024
y = 1024^(1/3) = 8cuberoot(2)
Do the others the same way.
let me know what you got for the rest. | <urn:uuid:63b40f35-0c68-4bf9-9a42-33c60787faea> | 3.515625 | 409 | Q&A Forum | Science & Tech. | 133.982806 | 95,630,826 |
CUED - Object-oriented programming Math Works Machine Translation The automated translation of this page is provided by a general purpose third party translator tool. Object-oriented programming with Matlab Why? Object-oriented programming is a popular mode of working and is supported by Java,
Introduction to Object-Oriented Programming OOP therefore bundles data (called There is nothing that OOP can do that could not be done without OOP. The programmer sees all methods that operate on the object in one place. OOP Introduction 1 Introduction to Object-Oriented Programming •Objects and classes •Abstract Data Types ADT •Encapsulation and information hiding
Object-oriented Matlab programming The user does not need to know anything about the function other than the interface (inputs and outputs). Programming Object-Oriented MATLAB a. components of MATLAB OOP packages, classes, properties, methods, and events b. the format of a Matlab class
Object Oriented Programming OOP They should only be manipulated by functions that also “belong to” the object. Object Oriented Programming OOP. Matlab documentation on object oriented programming. pdf htmlzip epub On Read the Docs
References and Books on Object OOP takes structured programming to the next level. References and Books on Object Oriented Programming in. to MATLAB Object-Oriented Programming" by. of book on Object Oriented Programming in Matlab.
Object oriented programming with matlab pdf:
Rating: 90 / 100
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doi:10.1038/nindia.2018.78 Published online 25 June 2018
Air pollution from crop stubble burning in some northern states of India – an environmental menace that makes headlines every year – is not confined to the north. Scientists now have evidence from NASA’s satellite images and ground stations in India that the burning of crop residue threatens a larger region in central and south India1.
An increase in finer black carbon (BC) particles and greenhouse gases from crop residue burning (CRB) has made the Indo-Gangetic basin a global hotspot for atmospheric pollutants and a place for recurring winter haze and toxic fog, the researchers say in their report.
"While, a lot of attention is given to the impact of CRB over the Indo-Gangetic basin (IGB), relatively less is known about its effect on the greater Indian peninsula," Ramesh Singh, a professor at Chapman University in California and one of the authors, told Nature India.
The analysis based on data from multiple sources is the ‘first work of its kind’ to assess the impact of CRB over India between 2003 and2017. Their results show "an increasing influence of CRB over the eastern parts of the IGB and also over parts of central and southern India."
Mechanized harvesting leaves residues in the field in the form of stalks, stubbles, and straws that are burnt by the farmers to clear the field for the next crop. Biomass burning after harvesting for wheat (during April-May) and rice (during October-November) is a recurring problem, in the northern states of Punjab, Haryana and Uttar Pradesh. The problem becomes severe in winters when large parts of northern India choke on smog and haze triggered by large scale crop residue burning.
The researchers – Sudipta Sarkar from NASA Maryland, IIT Kanpur alumnus Ramesh Singh at the Chapman University, California, and Ph.D. student Akshansha Chauhan from Sharda University, Greater Noida, Uttar Pradesh – looked at data from multiple sources. They culled data from NASA’s Imaging Spectro-radiometer, Ozone sensor, a number of other NASA satellite observations, ground stations in Kanpur and Hyderabad and global climate models. They used the ‘Emissions Database for Global Atmospheric Research’ to assess the magnitude of methane emissions – an inevitable by-product of CRB – and NASA’s database to obtain information on BC and dust column.
Data from the Kanpur and Hyderabad ground stations showed that BC aerosol-laden winds can travel longer distances at higher altitudes and impact far off places. While dust aerosol was largely confined to its source regions of western and north-western India, "the increase in BC is more evident along the eastern IGB and central India, conforming to the north-westerly wind direction in the post-monsoon period." According to the authors, most of the changes related to CRB are seen to be restricted within the lower 2 km of the atmosphere.
"Our results clearly show an increased preponderance of BC aerosols and finer particles, during the post-monsoon and wintertime, over the eastern IGB and central India," the authors say. The implications of higher black carbon levels in the post-monsoon ambient air-quality over eastern and Central India could be ‘far-reaching’, they say.
This deterioration of air quality, the researchers note, is of “great concern, especially over the eastern IGB that is already riddled with increasing pollution from various other sources like coal mining, fossil fuel combustion, industrial output and increased vehicular traffic, all of which are contributors to BC."
1. Sarkar, S. et al. Crop residue burning in northern India: Increasing threat to greater India. J. Geophys. Res. (2018) doi: 10.1029/2018JD028428 | <urn:uuid:0198c456-0bad-4e1c-a09b-0807485295eb> | 3.859375 | 817 | Truncated | Science & Tech. | 43.846837 | 95,630,846 |
Back draught: this beetle drinks the water its bumps collect.
Humans learn water-gathering trick from bumpy beetle.
A desert beetle turns fog into drinking water with its wings, new research reveals. Materials mimicking the insect could help humans survive harsh environments.
Southwest Africa’s Namib Desert is one of the hottest and driest places on Earth. There is no rain, but on about six mornings a month a fog blows in off the Atlantic and across the land at gale force.
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
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...
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Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
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03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
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Paleontologists have documented how dramatic shifts in climate have led to dramatic shifts in evolution.
One such event, the Grande Coupure, was a wipeout of many European mammal species 33.9 million years ago when global temperatures and precipitation declined sharply. What has been puzzling is that during the same transition between the Eocene and Oligocene periods, North American mammals fared much better.
The rise of the Rockies extended from British Columbia to Nevada in three phases between 56 and 23 million years ago. The rising mountains dried out the interior, preparing mammals for a major climate change event 34 million years ago, researchers say. European mammals were not so prepared.
Courtesy of Eronen et. al.
A new study explains why: the rise of the Rocky Mountains, already underway for millions of years, had predisposed populations to adapt to a cold, dry world.
'Regional tectonically driven surface uplift resulted in large-scale reorganization of precipitation patterns, and our data show that the mammalian faunas adapted to these changes,' write the study authors, including Christine Janis, professor of ecology and evolutionary biology at Brown University, in the Proceedings of the Royal Society B. 'We suggest that the late Eocene mammalian faunas of North America were already 'pre-adapted' to the colder and drier global conditions that followed the EO climatic cooling.'
The data in the study led by Jussi Eronen of the Senckenberg Research Institutes in Germany and the University of Helsinki in Finland, come from the authors' analysis of the fossil record of the two continents, combined with previous oxygen isotope data that reveal precipitation patterns, and tectonic models that show the growth of the Rocky Mountains. Specifically, the study shows that the rise of the range spread south in three phases from Canada starting more than 50 million years ago, down through Idaho, and finally into Nevada by 23 million years ago.
In the meantime, fossil mammal data show, precipitation in the interior regions dropped, and major shifts in mammal populations, such as an almost complete loss of primates, took place. Estimated rainfall based on plant fossils in Wyoming, for example, dropped from about 1,200 millimeters a year 56 million years ago to only 750 millimeters a year about 49 million years ago.
But across the region these correlated shifts occurred over tens of millions of years, leaving a well-adapted mix of mammals behind by the time of the Grand Coupure 34 million years ago.
In Europe, meanwhile, tectonic developments weren't a major factor driving local climate. When the global climate change happened, that continent's mammals were evolutionary sitting ducks. Other studies have already suggested that Europe's mammals were largely overrun and outcompeted by Asian mammals that were already living in colder and drier conditions.
Eronen said the findings should elevate the importance of collaboration across disciplines, for instance by integrating geoscience with paleontology, in the analysis of broad evolutionary patterns.
'Our results highlight the importance of regional tectonic and surface uplift processes on the evolution of mammalian faunas,' they wrote.
In addition to Eronen and Janis, the paper's other authors are C. Page Chamberlain of Stanford University and Andreas Mulch of the Senckenberg Institutes and Goethe University in Germany.
David Orenstein | EurekAlert!
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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17.07.2018 | Materials Sciences
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HTML (HyperText Markup Language) is the programming language used to create Web pages. The HTML code creates a layout for the text and graphic images that make up the document. Text can be formatted for paragraph layout and for font style with bold, italic, underline, color and various sizes. HTML also is used to create hypertext, or linked text. The user clicks on the highlighted hypertext to connect to another web page (via an URL or Uniform Resource Locator), graphic image or multimedia file. Graphic images, or "Inline Images", can also be linked to other files. Using links, web authors can connect to pages of their own or pages created by others. The World Wide Web is made of millions of HTML documents all linked with hypertext.
The basic element that makes up HTML code is a tag. HTML tags consist of less than and greater than signs (< and >) enclosing the HTML code.
These tags tell the web browser how the text and images should appear. Most tags have opening and closing tags that surround text, marking where to begin a certain kind of formatting and where to end that formatting.
The slash (/) in the ending HTML tag denotes a closing tag and the point where text following will NOT be effected by the tag. The initial tag turns on a formatting command; the closing tag turns off this formatting command.
Not all HTML tags have closing tags. Some tags do not directly effect text but format the document layout with line breaks and markers, or internal structure comments unseen by the viewer. HTML code is not case sensitive.
All HTML documents contain certain elements, or tags, that define the major parts of the web page. These tags are:
Here is the required order for the main HTML tags:
<HEAD> <TITLE>Title of the Web Page </TITLE> </HEAD>
<BODY> All the text and graphic images of the document </BODY>
Basic HTML Tags
Sample Web Page
Here is a simple HTML document:
<TITLE>WR 227 Instructor</TITLE>
<H6><A HREF="#links">Skip to Links</A></H6>
<Center><H1>WR 227 Technical Writing I</H1></Center>
<Center><H2 >George Knox, Instructor/Writer/Web Author:</H2></Center>
<P>Knox has a Master of Arts in English from Portland State University with training in technical writing and editing, and web development. He has taught Career Development, Web Design and Writing through Portland Community College and Oregon State University.</P>
<P>For the past 10 years, George Knox has worked with the public and private sectors developing marketing, recruiting and educational programs and materials. He has experience in marcom, media, technical and grant writing. He has worked with a wide range of clients, but specializes in the high technology and engineering fields.</P>
<LI><A HREF="http://www.pcc.edu/">Portland Community College Homepage</A>
<LI><A HREF="wrlinks.htm">Web Resources for Technical Writing</A>
<P><FONT SIZE=-2><B>Instructor: </B>George Knox; <B>Phone: </B>503-977-4475; <B>E-mail: </B><A HREF="mailto:email@example.com">firstname.lastname@example.org</A>; <B>Office: </B>Sy CC 221</FONT> </P>
<CENTER><P><IMG SRC="4prule.gif" ></CENTER>
<P><I>Last Modified: July 5, 1999.</I></P>
Click here to see what the web page looks like.
Advanced HTML & Other Ways to Web
There are many more HTML tags used for web pages. If you are interested in learning more about HTML and web design, or would like to create your own web page, check out Geo's Web Corner. There you will find tutorials, free downloads of useful web tools, and other resources to help you develop and publish web pages of your own. (You'll even find ways to build a page without knowing HTML.)
|The Quick and Easy Guides for Writers|
Written by: George Knox © 1999
Last Modified: July 5, 1999. | <urn:uuid:8424a8e3-5740-4426-93c2-dd35a65afe50> | 4.5 | 913 | Knowledge Article | Software Dev. | 64.300014 | 95,630,887 |
A Binary Star is a pair of stars that orbit each other. Double Star means the same thing except that it also includes stars that are not orbiting and not close together but happen to be on the same line of sight from Earth, referred to as Apparent Binary stars.
Binary (or more) star systems are said to be common: the best number I've found is that roughly third of all star systems have two or more stars. They are extremely useful in the study of stellar physics, both to use the orbital dynamics for Stellar Parameter Determination, and for those close enough to interact further, giving additional situations to observe, to infer and test the physics of Stellar Structure.
A system can have three or more stars. The term Multiple Star System is sometimes reserved for this case.
A common classification of binary stars is based on the method by which they were determined to be binary:
Another classification is based upon how close they are and how much they interact:
A binary star's Mass Ratio (μ) is the ratio of the two masses, i.e., 1 for stars of equal mass. When the Total Mass can also be determined, e.g., from the orbital period and size, the mass of each star is evident.
Binary stars generally have similar composition (as shown by their spectra), as if they were formed together.
Given the large scale of distances between the stars, the different sizes/Spectral Classes of the individual stars binary stars show a wide variety, and the interactions produce characteristics unseen in non-binary stars. For example:
The commonly-used system for referring to the individual stars of a binary/multiple star system are indicated by following the name with "A" for the brightest, "B" for the second brightest, then "C" and so on. For example, the two stars making up Sirius are termed "Sirius A" and "Sirius B". If two are very close and a third is distant, the two close stars might use lower-case suffixes, i.e., "Aa" and "Ab", with the further member called "B".
Aitken Double Star Catalogue (ADS)
Black Widow Pulsar (B1957+20)
Black Hole Binary (BHB)
Double-Line Spectroscopic Binary
Extra Solar Planet
Guide Star Catalog (GSC)
Hulse-Taylor Binary (PSR B1913+16)
Radial Velocity (RV)
Rossiter-McLaughlin Effect (RM Effect)
Stellar Population Synthesis (SPS)
Stellar Distance Determination
Stellar Parameter Determination
Transit Timing Variations (TTV)
Turn-off Point (TO) | <urn:uuid:aad489f4-4001-4b6d-89e3-c0704e192bc1> | 3.859375 | 567 | Knowledge Article | Science & Tech. | 44.826515 | 95,630,903 |
Estimating Prevalence of a Trait
When sampling units selected from a population and measurements indicate presence or absence of a trait, it is possible to either classify every sampling unit as positive/negative or estimate the prevalence of the trait. The former is desired when the interest is in identifying all sampling units that test positive (and hence possess the trait). The latter is useful when the interest is not in the status of individual sampling units that possess the trait. The problem, then, is to estimate the sampling units in the population that possess the trait, when presence. Absence measurements are obtained on composite samples. Here, the values on the individual sampling units in the population are assumed to be independent and identically distributed random variables.
KeywordsComposite Sample Maximum Likelihood Estimator Sampling Unit Unbiased Estimator Taylor Series Expansion
- Bartlett, M. S. (1935). Mathematical appendix to a paper, by G. E. Blackman, entitled “A study by statistical methods of the distribution of species in grassland associations.” Ann. Bot. 49:749–777.Google Scholar
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Mouse Model May Also Aid In Discovery of Gene Function
Researchers at the University of Pennsylvania School of Medicine have bred a mouse to model human L1 retrotransposons, the so-called "jumping genes." Retrotransposons are small stretches of DNA that are copied from one location in the genome and inserted elsewhere, typically during the genesis of sperm and egg cells. The L1 variety of retrotransposons, in particular, are responsible for about one third of the human genome.
The mouse model of L1 retrotransposition is expected to increase our understanding of the nature of jumping genes and their implication in disease. According to the Penn researchers, the mouse model may also prove to be a useful tool for studying how a gene functions by knocking it out through L1 insertion. Their report is in the December issue of Nature Genetics and currently available online (see below for URL).
Greg Lester | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
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Reading the fossil record, a paleontologist can peer into evolutionary history and see the surface features that plants and animals and, occasionally, microbes have left behind.
Now, scouring the genome of a Japanese yeast, scientists have found a trackway of fossil genes in the making, providing a rare look at how an organism, in response to the demands of its environment, has changed its inner chemistry and lost the ability to metabolize a key sugar.
The finding is a snapshot of evolution at work showing, at the most fundamental level, how traits and features are discarded by virtually all forms of life when they are no longer needed. "Many people think evolution is always happening in a forward direction," that new features are just tacked on, says Sean B. Carroll, a professor of molecular biology at the Howard Hughes Medical Institute at the University of Wisconsin-Madison. "The other side of the coin is that we lose things. Losses as well as gains make up the story of evolution."
Sean B. Carroll | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:018f8f34-b581-4753-ba06-6be042c72f18> | 3.421875 | 792 | Content Listing | Science & Tech. | 38.149191 | 95,630,916 |
A Water Channel Network in Cell Membranes of the Filter Chamber of Homopteran Insects
Water is the most ubiquitous molecule in the living cell and movement of water across the cell membrane accompanies fundamental cell functions. All biological membranes exhibit some water permeability as a result of diffusion through the lipid bilayer and osmotic gradients constitute the driving force for water flow. Osmotic water permeability is therefore of the highest relevance. However, some cells have the ability to transport water across their cell membrane at greatly accelerated rates, for example mammalian red blood cells, epithelial cells of the renal proximal tubules. Water permeability in such cells is simply too high to be accounted for by lipid-mediated diffusion, thus leading biophysicists to predict that water-selective channels must exist. The search for water channel began not surprisingly in tissues that had been already identified from physiological studies as having high water permeabilities. But the molecular basis of water channels remained elusive for a long time, since many attempts to determine its structure by biochemical approaches and expression cloning were unsuccessful. The reasons of this failure were linked to the inability of the water channel to be labeled by its substrate, the lack of highly specific inhibitors and the basal diffusional permeability of cell membranes.
KeywordsWater Permeability Water Channel Xenopus Oocyte Osmotic Water Permeability Filter Chamber
Unable to display preview. Download preview PDF.
- Agre P., Preston G.M., Smith B.L., Jung J.S., Raina S., Moon C., Guggino W.B. and Nielsen S., Am. J. Physiol. 265 (1993) F463-F476.Google Scholar
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Give It a Lift with a Lever
|Time Required||Very Short (≤ 1 day)|
|Material Availability||Readily available|
|Cost||Very Low (under $20)|
AbstractDid you know that you can lift an object that's heavier than you are? Just use a lever! In this science project you'll build a tabletop lever and measure how much effort it takes to lift an object using it.
In this science project you will build a tabletop lever and investigate how changing the length of the effort arm affects the amount of effort it takes to lift an object.
Cite This PageGeneral citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.
Last edit date: 2018-03-24
Today, skyscrapers, homes, and other buildings are all created using the help of machines to lift heavy pieces of wood, steel, and stone into place. But have you ever wondered how large structures, like the pyramids in Egypt, were built before cranes and bulldozers existed? The answer is that they used simple machines. Simple machines are tools like an inclined plane, a pulley, a wheel and axle, or a lever, that make it easier to do work. These simple machines give the user a mechanical advantage. Mechanical advantage is the multiplication of the effort the user puts in. This means that if you use a lever and the mechanical advantage it provides, you can lift an object that's much heavier than you are because the lever multiplies your effort!
Levers have several important parts. There is a fulcrum, which is the point on which the beam can balance and thus, move freely up and down. The end holding the object (also called the load) that you want to lift is called the load end. The end you apply weight to in order to try to move the load is called the effort end. In Figure 1, the see-saw is the lever and the fulcrum is where the see-saw rests on the ground, allowing the see-saw to move up and down. One girl is sitting at the load end, and her lighter friend is sitting at the effort end. The space between the effort end and the fulcrum is called the effort arm, while the space between the load end and the fulcrum is called the load arm.
Before ancient builders could use levers to construct their monuments, they needed to calculate the weight of each block, how much effort it would take to lift each block, and what size lever they would have to make. In short, they needed to know how levers worked. In this science project, you will build a lever and figure out how it works. A massive stone block would be hard to find though, so instead, you'll use a bar of soap as the load. After you build your tabletop lever, you will experiment to discover how much effort, as measured by the number of pennies, it takes to lift the soap load. Do you think the amount of effort required will change depending on the length of the effort arm? Try it and see!
Terms and Concepts
Before you start this science project you'll need to understand these terms and be able to answer the questions below. Have an adult help you research them on the Internet or look them up in a book.
- Simple machine
- Mechanical advantage
- Load end
- Effort end
- Effort arm
- Load arm
- What are levers used for?
- What are the three classes of levers?
- Can you identify levers that you use in your life?
This project was originally based on Episode 604, "Escape from Merlin's Maze," of Cyberchase by PBS Kids Go!. This particular episode is no longer available online, but you can read about it here:
- PBS parents (n.d.). Cyberchase. Season 6. Retrieved March 6, 2018 from http://www.pbs.org/parents/cyberchase/episodes/season-6/
An encyclopedia is a great place to start your background research. In addition, you may want to check out these websites, which describe the three classes of levers, and the use of levers in everyday life.
- Ryan, V. (2002). Levers. Retrieved March 16, 2008 from http://www.technologystudent.com/forcmom/lever1.htm
- Wikipedia contributors. (2008, March 13). Lever. Wikipedia: The Free Encyclopedia. Retrieved March 16, 2008 from http://en.wikipedia.org/w/index.php?title=Lever&oldid=198005759
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Materials and Equipment
- Metric ruler (preferably one that is stiff and has centimeter markings)
- Plastic sandwich bag (1)
- Tape (preferably masking tape)
- Pen or pencil
- Bar of soap (still in its packaging)
- Pennies (approximately $3 worth; alternatively, marbles, beans, or some other small numerous item will work)
- Lab notebook
- Graph paper
Remember Your Display Board Supplies
Poster Making Kit
ArtSkills Trifold with Header
- To start this project, you will need to build your lever. The ruler will be the beam for the lever. Tape a bar of soap to one end of the ruler. The soap is the load you will be trying to lift.
Next you will need to construct a container out of your plastic bag to hold the pennies in. The bag and the pennies you'll place in the bag will be the effort. As you add more pennies, you are increasing the weight in the bag-and thus, the effort-until you eventually have enough effort to lift the soap bar (the load).
- Put a piece of tape approximately 1 centimeter (cm) from the zipper part of the top of a plastic sandwich bag. Do this on both the inside and the outside of one side of the plastic bag. See Figure 2.a. below.
- Fold the taped section in half, width-wise. Using a pair of scissors, cut a slit long enough to allow the ruler to slip through. See Figure 2.b. below.
- Slip the free end of the ruler (the effort end) into the slit. Tape the bag to the ruler so it does not slide around. Be careful not to tape the bag closed, as you will need to add pennies inside it (the effort).
Figure 2.a. This picture shows the plastic bag strengthened with two strips of tape.
Figure 2.b. To cut a slit in the bag, fold the tape in half, as shown, and cut a slit for the ruler to fit in.
- Tape a pen or pencil to the edge of a table; this will be the fulcrum for your lever.
Place your lever on the fulcrum. The bar of soap (the load) should be resting on the table, and the bag for the pennies (the effort) should be dangling over the edge of the table. See Figure 3 below.
Figure 3. Your tabletop lever should look similar to this when you finish building it. Remember to tape the fulcrum securely to the table!
Now you are ready to test your lever! You know that changing the length of the effort arm (the distance between the fulcrum and the effort end) changes how much effort has to be used to lift the load.
- Position the ruler so that the length of the effort arm is 6 cm. You can use the markings on the ruler to measure 6 cm.
- Add pennies to the bag, one at a time, counting as you go, until the bar of soap lifts off the table. Watch out, it might fall off the table!
- In your lab notebook, record both the length of the effort arm, and the number of pennies it took to lift the load in a data table like the one below.
Length of Effort Arm (cm) # of Pennies to Lift Load 6 cm 8 cm 10 cm
- Increase the length of the effort arm by 2 cm (total length should now be 8 cm) and repeat step 5 again. Did it take more or fewer pennies to lift the load? Record your findings.
- Continue increasing the effort arm length by 2-cm increments and retrying the experiment until the effort arm measures 24 cm. Don't forget to record all the data in your data table.
Analyze your data. You can make a line graph with the length of the effort arm on the x-axis and the number of pennies it takes to lift the load on the y-axis. Do you see a pattern? What happens when you double the distance? What happens when you quadruple the distance?
To use the computer to make your graph you can visit the Create A Graph website.
- You are trying to determine the relationship between two variables: the effort (# of pennies) it takes to lift the load (bar of soap) and the length of the effort arm, so choose the XY graph.
Select the Data Tab, fill in:
- The graph title
- X-axis label (remember, the x-axis is the length of the effort arm)
- Y-axis label (remember, the y-axis is the number of pennies is takes to lift the load)
- In the Data Set box, tell the program you have 12 data points.
- For each point, fill in the length of the effort arm (x) and the number of pennies (y). So, point 1x would be 6 since you took your first data reading when the effort arm was 6 cm long. Point 1y would be the number of pennies, recorded in your data table, that it took to lift the soap bar at an effort arm length of 6 cm.
- You can use the remaining options to customize the font styles and colors of your chart.
- When you are done, print it out.
Communicating Your Results: Start Planning Your Display BoardCreate an award-winning display board with tips and design ideas from the experts at ArtSkills.
If you like this project, you might enjoy exploring these related careers:
Mechanical EngineerMechanical engineers are part of your everyday life, designing the spoon you used to eat your breakfast, your breakfast's packaging, the flip-top cap on your toothpaste tube, the zipper on your jacket, the car, bike, or bus you took to school, the chair you sat in, the door handle you grasped and the hinges it opened on, and the ballpoint pen you used to take your test. Virtually every object that you see around you has passed through the hands of a mechanical engineer. Consequently, their skills are in demand to design millions of different products in almost every type of industry. Read more
PhysicistPhysicists have a big goal in mind—to understand the nature of the entire universe and everything in it! To reach that goal, they observe and measure natural events seen on Earth and in the universe, and then develop theories, using mathematics, to explain why those phenomena occur. Physicists take on the challenge of explaining events that happen on the grandest scale imaginable to those that happen at the level of the smallest atomic particles. Their theories are then applied to human-scale projects to bring people new technologies, like computers, lasers, and fusion energy. Read more
Physics TeacherOur universe is full of matter and energy, and how that matter and energy moves and interacts in space and time is the subject of physics. Physics teachers spend their days showing and explaining the marvels of physics, which underlies all the other science subjects, including biology, chemistry, Earth and space science. Their work serves to develop the next generation of scientists and engineers, including all healthcare professionals. They also help all students better understand their physical world and how it works in their everyday lives, as well as how to become better citizens by understanding the process of scientific research. Read more
Mechanical Engineering TechnicianYou use mechanical devices every day—to zip and snap your clothing, open doors, refrigerate and cook your food, get clean water, heat your home, play music, surf the Internet, travel around, and even to brush your teeth. Virtually every object that you see around has been mechanically engineered or designed at some point, requiring the skills of mechanical engineering technicians to create drawings of the product, or to build and test models of the product to find the best design. Read more
- What happens if you double the load by adding two soap bars? Does the effort (number of pennies in this science project) required to lift the load also double? What if you triple or quadruple the load?
- Use a kitchen scale, such as the Fast Weigh MS-500-BLK Digital Pocket Scale, 500 by 0.1 G, available from Amazon.com, to determine how much the load (soap bar) weighs and how much the effort (number of pennies needed to lift the soap bar) weighs. Can you use this information to calculate how much effort it would take to lift you?
- In your background research you learned that there were several classes of levers. In the project above, you built a class 1 lever. Try building a class 2 lever, too. Compare the class 1 and 2 levers. Do they require the same effort to lift the load? Remember to keep the distance between the fulcrum and the effort end the same when comparing the levers!
- If you want to explore more fun science projects that use levers, try Balancing the Load: The See-Saw as a Simple Machine or Effect of Trebuchet Arm Length or Counterweight Mass on Projectile Distance.
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Looking for more science fun?
Try one of our science activities for quick, anytime science explorations. The perfect thing to liven up a rainy day, school vacation, or moment of boredom.Find an Activity | <urn:uuid:73cc3ce2-0f3a-4185-b4bd-9c1efd37dd7d> | 4.125 | 3,141 | Tutorial | Science & Tech. | 64.676503 | 95,630,936 |
Pumps can be classified by their method of displacement into positive displacement pumps (trap fluid to increase pressure), impulse pumps (trap air to increase pressure), velocity pumps (move water mass to increase pressure), gravity pumps (weight of fluid; ala syphon / Heron's fountain), steam pumps (boil at bottom, distil at top).
Displacement pumps are certainly the most common and can be divide into several types:
In a spiral pump, the water is trapped by gravity inside the ever higher coil of the spiraling pipe and is then pushed out the center. Paddles turn the spiral. Also:
Commonly found in aquariums (although impeller pumps seem to be making headway) these work by injecting air into the bottom of a vertical tube which is open at both ends and placed with its top sticking up above the water surface and its bottom some depth below the waters surface. The bubbles rise and expand and water is driven up the tube by the ascending bubbles. Water (and air) exit from the top of the tube.
A bubble pump operates most efficiently when the bubbles fill the tube from side to side and are seperated from one another by a slug of water. The maximum diameter tube in which this "slug flow" occurs is given by the following equation (Chisholm, 1983):
where vf and vg are the specific volumes of the liquid and vapor respectively, and à (sigma) is the surface tension. Note, for a given fluid in a tube of diameter greater than that predicted by this equation, slug flow will never occur.
When used to pump water, 60% of the length of the pump must be submerged and you will need 0.43 psi of air pressure for each foot of water above the outlet of your air tube.
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New research from NASA's Jet Propulsion Laboratory indicates that climate change will cause atmospheric rivers to become increasingly longer and wider by the end of this century.
Graphic courtesy of NOAA.
Atmospheric rivers are long, and narrow (250-375 miles wide) jets of air that carry massive amounts of water vapor from the tropics to regions that can be located as far away as the middle and high latitudes.
Atmospheric rivers can bring much needed precipitation but can also be responsible for major flooding and extreme snowfall.
An example of an atmospheric river (circled) impacting the U.S. West Coast. Image courtesy NOAA.
The research team, led by Duane Waliser of NASA's JPL, stated that the results of this study are based on the assumption that greenhouse gas emissions will continue at the current rate.
Even though atmospheric rivers will likely become longer and wider, the results showed that there will be about a 10 percent decrease in atmospheric rivers globally by the end of the 21st century.
Regardless of the decrease, the trend toward longer and wider atmospheric rivers is expected to produce a 50 percent increase in heavy rain and strong wind events globally. In addition, the frequency of the most intense atmospheric rivers may nearly double by the end of the 21st century.
For information on how the research team cam to their conclusions, see the NASA News report.
Comments that don't add to the conversation may be automatically or manually removed by Facebook or AccuWeather. Profanity, personal attacks, and spam will not be tolerated.
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.
New research indicates that climate change will cause atmospheric rivers to become increasingly longer and wider by the end of this century. | <urn:uuid:d62af62d-e23b-45fa-b2af-82b593af4463> | 3.859375 | 493 | News Article | Science & Tech. | 45.543634 | 95,630,962 |
The Solar Longitude (Abbrev: S.L., λ ☉) is 220 degrees, this value is the the date of maximum activity. It is measured as a degree with zero degree indicating spring equinox (roughly March 21st/22nd). 90 is the Summer Solstice, 180 is the Autumn Equinox and 270 is the Winter Solstice. This degree is independent of the calender. AMS .
The source of the meteor shower is 2P/Encke. The coordinates can also be determined by the Right Ascension (48.9) and the Declination (20.7).
The Zenith Hourly Rate or how many you expect to see during the hour is 5. The ZHR can radically increase if the comet or associated object is close by. The speed/velocity of the Meteor Shower particles is 28 km/s. The population index of the meteor shower is 2. The population index refers to the magnitude distribution of the meteorites, the smaller the index, the brighter the meteors are, the higher, the dimmer the meteors are. For this particular meteor shower, faint meteors are more frequent.
|Max Activity Date||12 Nov|
|Activity Period||Oct 12-Dec 2|
|Solar Longitude / λ ☉||220 °|
|Zenith Hourly Rate||5| | <urn:uuid:d40d1720-c734-45e6-a5ba-403a571d3a09> | 2.703125 | 284 | Knowledge Article | Science & Tech. | 64.065221 | 95,630,972 |
A Full-text Website Search Engine Powered by Lucene and The Depth First Search Algorithm
- Modinat. A. Mabayoje, O. S. Oni, Olawale S. Adebayo
- International Journal of Computer Network and Information Security ico_openaccess
- in 2013
- Cited Count
- Engineering > Computer Science
- Full Text search engine, Relational Database, Information Retrieval, Lucene, Depth first search algorithm, Electronic computers. Computer science, QA75.5-76.95, Instruments and machines, QA71-90, Mathematics, QA1-939, Science, DOAJ:Computer Science, DOAJ:Technology and Engineering
With the amount of available text data on the web growing rapidly, the need for users to search such information is dramatically increasing. Full text search engines and relational databases each have unique strengths as development tools but also have overlapping capabilities. Both can provide for storage and update of data and both support search of the data. Full text systems are better for quickly searching high volumes of unstructured text for the presence of any word or combination of words. They provide rich text search capabilities and sophisticated relevancy ranking tools for ordering results based on how well they match a potentially fuzzy search request. Relational databases, on the other hand, excel at storing and manipulating structured data -- records of fields of specific types (text, integer, currency, etc.). They can do so with little or no redundancy. They support flexible search of multiple record types for specific values of fields, as well strong tools for quickly and securely updating individual records. The web being a collection of largely unstructured document which is ever growing in size, the appeal of using RDBMS for searching this collection of documents has become very costly.This paper describes the architecture, design and implementation of a prototype website search engine powered by Lucene to search through any website. This approach involves the development of a small scale web crawler to gather information from the desired website. The gathered information are then converted to a Lucene document and stored in the index. The time taken to search the index is very short when compared with how long it takes for a relational database to process a query.
No relevant information is available
If you register references through the customer center, the reference information will be registered as soon as possible. | <urn:uuid:86a5a9ee-fbff-4a03-8226-ddece56b7e7e> | 2.671875 | 489 | Academic Writing | Software Dev. | 29.178156 | 95,630,980 |
Environmental impact of the energy industry
This article is written like a personal reflection or opinion essay that states a Wikipedia editor's personal feelings about a topic. (March 2018) (Learn how and when to remove this template message)
The environmental impact of the energy industry is diverse. Energy has been harnessed by human beings for millennia. Initially it was with the use of fire for light, heat, cooking and for safety, and its use can be traced back at least 1.9 million years. In recent years there has been a trend towards the increased commercialization of various renewable energy sources.
Rapidly advancing technologies can potentially achieve a transition of energy generation, water and waste management, and food production towards better environmental and energy usage practices using methods of systems ecology and industrial ecology.
- 1 Issues
- 2 Mitigation
- 3 See also
- 4 References
- 5 External links
The scientific consensus on global warming and climate change is that it is caused by anthropogenic greenhouse gas emissions, the majority of which comes from burning fossil fuels with deforestation and some agricultural practices being also major contributors. A 2013 study showed that two thirds of the industrial greenhouse gas emissions are due to the fossil-fuel (and cement) production of just ninety companies around the world (between 1751 and 2010, with half emitted since 1986).
Although there is a highly publicized denial of climate change, the vast majority of scientists working in climatology accept that it is due to human activity. The IPCC report Climate Change 2007: Climate Change Impacts, Adaptation and Vulnerability predicts that climate change will cause shortages of food and water and increased risk of flooding that will affect billions of people, particularly those living in poverty.
One measurement of greenhouse gas related and other Externality comparisons between energy sources can be found in the ExternE project by the Paul Scherrer Institut and the University of Stuttgart which was funded by the European Commission. According to that study, hydroelectric electricity produces the lowest CO2 emissions, wind produces the second-lowest, nuclear energy produces the third-lowest and solar photovoltaic produces the fourth-lowest.
Similarly, the same research study (ExternE, Externalities of Energy), undertaken from 1995 to 2005 found that the cost of producing electricity from coal or oil would double over its present value, and the cost of electricity production from gas would increase by 30% if external costs such as damage to the environment and to human health, from the airborne particulate matter, nitrogen oxides, chromium VI and arsenic emissions produced by these sources, were taken into account. It was estimated in the study that these external, downstream, fossil fuel costs amount up to 1%-2% of the EU’s entire Gross Domestic Product (GDP), and this was before the external cost of global warming from these sources was even included. The study also found that the environmental and health costs of nuclear power, per unit of energy delivered, was €0.0019/kWh, which was found to be lower than that of many renewable sources including that caused by biomass and photovoltaic solar panels, and was thirty times lower than coal at €0.06/kWh, or 6 cents/kWh, with the energy sources of the lowest external environmental and health costs associated with it being wind power at €0.0009/kWh.
Biofuel is defined as solid, liquid or gaseous fuel obtained from relatively recently lifeless or living biological material and is different from fossil fuels, which are derived from long-dead biological material. Various plants and plant-derived materials are used for biofuel manufacturing.
Unsustainable firewood harvesting can lead to loss of biodiversity and erosion due to loss of forest cover. An example of this is a 40-year study done by the University of Leeds of African forests, which account for a third of the world's total tropical forest which demonstrates that Africa is a significant carbon sink. A climate change expert, Lee White states that "To get an idea of the value of the sink, the removal of nearly 5 billion tonnes of carbon dioxide from the atmosphere by intact tropical forests is at issue.
According to the U.N. the African continent is losing forest twice as fast as the rest of the world. "Once upon a time, Africa boasted seven million square kilometers of forest but a third of that has been lost, most of it to charcoal."
Fossil fuel use
The three fossil fuel types are coal, petroleum and natural gas. It was estimated by the Energy Information Administration that in 2006 primary sources of energy consisted of petroleum 36.8%, coal 26.6%, natural gas 22.9%, amounting to an 86% share for fossil fuels in primary energy production in the world.
In 2013 the burning of fossil fuels produced around 32 billion tonnes (32 gigatonnes) of carbon dioxide and additional air pollution. This caused negative externalities of $4.9 trillion due to global warming and health problems (> 150 $/ton carbon dioxide). Carbon dioxide is one of the greenhouse gases that enhances radiative forcing and contributes to global warming, causing the average surface temperature of the Earth to rise in response, which climate scientists agree will cause major adverse effects.
The environmental impact of coal mining and burning is diverse. Legislation passed by the U.S. Congress in 1990 required the United States Environmental Protection Agency (EPA) to issue a plan to alleviate toxic pollution from coal-fired power plants. After delay and litigation, the EPA now has a court-imposed deadline of March 16, 2011, to issue its report.
The environmental impact of petroleum is often negative because it is toxic to almost all forms of life. The possibility of climate change exists. Petroleum, commonly referred to as oil, is closely linked to virtually all aspects of present society, especially for transportation and heating for both homes and for commercial activities.
Natural gas is often described as the cleanest fossil fuel, producing less carbon dioxide per joule delivered than either coal or oil., and far fewer pollutants than other fossil fuels. However, in absolute terms it does contribute substantially to global carbon emissions, and this contribution is projected to grow. According to the IPCC Fourth Assessment Report, in 2004 natural gas produced about 5,300 Mt/yr of CO2 emissions, while coal and oil produced 10,600 and 10,200 respectively (Figure 4.4); but by 2030, according to an updated version of the SRES B2 emissions scenario, natural gas would be the source of 11,000 Mt/yr, with coal and oil now 8,400 and 17,200 respectively. (Total global emissions for 2004 were estimated at over 27,200 Mt.)
In addition, natural gas itself is a greenhouse gas far more potent than carbon dioxide when released into the atmosphere but is released in smaller amounts.
The environmental impact of electricity generation is significant because modern society uses large amounts of electrical power. This power is normally generated at power plants that convert some other kind of energy into electrical power. Each such system has advantages and disadvantages, but many of them pose environmental concerns.
The environmental impact of reservoirs is coming under ever increasing scrutiny as the world demand for water and energy increases and the number and size of reservoirs increases. Dams and the reservoirs can be used to supply drinking water, generate hydroelectric power, increasing the water supply for irrigation, provide recreational opportunities and for flood control. However, adverse environmental and sociological impacts have also been identified during and after many reservoir constructions. Whether reservoir projects are ultimately beneficial or detrimental—to both the environment and surrounding human populations— has been debated since the 1960s and probably long before that. In 1960 the construction of Llyn Celyn and the flooding of Capel Celyn provoked political uproar which continues to this day. More recently, the construction of Three Gorges Dam and other similar projects throughout Asia, Africa and Latin America have generated considerable environmental and political debate.
The routine health risks and greenhouse gas emissions from nuclear fission power are smaller than those associated with coal, oil and gas. However, there is a "catastrophic risk" potential if containment fails, which in nuclear reactors can be brought about by over-heated fuels melting and releasing large quantities of fission products into the environment. The most long-lived radioactive wastes, including spent nuclear fuel, must be contained and isolated from humans and the environment for hundreds of thousands of years. The public is sensitive to these risks and there has been considerable public opposition to nuclear power. Despite this potential for disaster, normal fossil fuel related pollution is still considerably more harmful than any previous nuclear disaster.
The 1979 Three Mile Island accident and 1986 Chernobyl disaster, along with high construction costs, ended the rapid growth of global nuclear power capacity. A further disastrous release of radioactive materials followed the 2011 Japanese tsunami which damaged the Fukushima I Nuclear Power Plant, resulting in hydrogen gas explosions and partial meltdowns classified as a Level 7 event. The large-scale release of radioactivity resulted in people being evacuated from a 20 km exclusion zone set up around the power plant, similar to the 30 km radius Chernobyl Exclusion Zone still in effect.
The environmental impact of wind power when compared to the environmental impacts of fossil fuels, is relatively minor. According to the IPCC, in assessments of the life-cycle global warming potential of energy sources, wind turbines have a median value of between 12 and 11 (gCO2eq/kWh) depending, respectively, on if offshore or onshore turbines are being assessed. Compared with other low carbon power sources, wind turbines have some of the lowest global warming potential per unit of electrical energy generated.
While a wind farm may cover a large area of land, many land uses such as agriculture are compatible with it, as only small areas of turbine foundations and infrastructure are made unavailable for use.
There are reports of bird and bat mortality at wind turbines as there are around other artificial structures. The scale of the ecological impact may or may not be significant, depending on specific circumstances. Prevention and mitigation of wildlife fatalities, and protection of peat bogs, affect the siting and operation of wind turbines.
Aesthetic aspects of wind turbines and resulting changes of the visual landscape are significant. Conflicts arise especially in scenic and heritage protected landscapes.
Energy conservation refers to efforts made to reduce energy consumption. Energy conservation can be achieved through increased efficient energy use, in conjunction with decreased energy consumption and/or reduced consumption from conventional energy sources.
Energy conservation can result in increased financial capital, environmental quality, national security, personal security, and human comfort. Individuals and organizations that are direct consumers of energy choose to conserve energy to reduce energy costs and promote economic security. Industrial and commercial users can increase energy use efficiency to maximize profit.
Energy policy is the manner in which a given entity (often governmental) has decided to address issues of energy development including energy production, distribution and consumption. The attributes of energy policy may include legislation, international treaties, incentives to investment, guidelines for energy conservation, taxation and other public policy techniques.
- Ecological energetics
- Environmental impact of hydraulic fracturing
- Energy economics
- Energy accounting
- Energy transformation
- Energy quality
- Environmental impact of aviation
- Environmental impact of electricity generation
- Industrial ecology
- Index of energy articles
- Energy and Environment
- List of energy storage projects
- List of environmental issues
- Low-carbon power
- Systems ecology
- The Venus Project
- BP: Workbook of historical data (xlsx), London, 2012
- "Energy Consumption: Total energy consumption per capita". Earth trends Database. World Resources Institute. Archived from the original on 12 December 2004. Retrieved 2011-04-21.
- Bowman, D. M. J. S; Balch, J. K; Artaxo, P; Bond, W. J; Carlson, J. M; Cochrane, M. A; d'Antonio, C. M; Defries, R. S; Doyle, J. C; Harrison, S. P; Johnston, F. H; Keeley, J. E; Krawchuk, M. A; Kull, C. A; Marston, J. B; Moritz, M. A; Prentice, I. C; Roos, C. I; Scott, A. C; Swetnam, T. W; Van Der Werf, G. R; Pyne, S. J (2009). "Fire in the Earth System". Science. 324 (5926): 481–4. Bibcode:2009Sci...324..481B. doi:10.1126/science.1163886. PMID 19390038.
- Kay, J. (2002). Kay, J.J. "On Complexity Theory, Exergy and Industrial Ecology: Some Implications for Construction Ecology." Archived 6 January 2006 at the Wayback Machine. In: Kibert C., Sendzimir J., Guy, B. (eds.) Construction Ecology: Nature as the Basis for Green Buildings, pp. 72–107. London: Spon Press. Retrieved on: 2009-04-01.
- Baksh B., Fiksel J. (2003). "The Quest for Sustainability: Challenges for Process Systems Engineering" (PDF). American Institute of Chemical Engineers Journal. 49 (6): 1355.
- Douglas Starr, "The carbon accountant. Richard Heede pins much of the responsibility for climate change on just 90 companies. Others say that's a cop-out", Science, volume 353, issue 6302, 26 August 2016, pages 858-861.
- Richard Heede, "Tracing anthropogenic carbon dioxide and methane emissions to fossil fuel and cement producers, 1854–2010", Climatic Change, January 2014, volume 122, issue 1, pages 229–241 (PDF).
- "Billions face climate change risk". BBC NEWS Science/Nature. 2007-04-06. Retrieved 2011-04-22.
- Rabl A.; et al. (August 2005). "Final Technical Report, Version 2" (PDF). Externalities of Energy: Extension of Accounting Framework and Policy Applications. European Commission. Archived from the original (PDF) on 7 March 2012.
- "External costs of electricity systems (graph format)". ExternE-Pol. Technology Assessment / GaBE (Paul Scherrer Institut). 2005. Archived from the original on 1 November 2013.
- New research reveals the real costs of electricity in Europe
- ExternE-Pol, External costs of current and advanced electricity systems, associated with emissions from the operation of power plants and with the rest of the energy chain, final technical report. See figure 9, 9b and figure 11
- Rowan, Anthea (2009-09-25). "Africa's burning charcoal problem". BBC NEWS Africa. Retrieved 2011-04-22.
- "International Energy Annual 2006". Archived from the original on 5 February 2009. Retrieved 8 February 2009.
- Ottmar Edenhofer, King Coal and the queen of subsidies. In: Science 349, Issue 6254, (2015), 1286, doi:10.1126/science.aad0674.
- "Environmental impacts of coal power: air pollution". Union of Concerned Scientists. 2009. Retrieved 2011-04-22.
- Natural Gas and the Environment Archived 3 May 2009 at the Wayback Machine.
- IPCC Fourth Assessment Report (Working Group III Report, Chapter 4)
- Poulakis, Evangelos; Philippopoulos, Constantine (2017). "Photocatalytic treatment of automotive exhaust emissions". Chemical Engineering Journal. 309: 178. doi:10.1016/j.cej.2016.10.030.
- International Panel on Fissile Materials (September 2010). "The Uncertain Future of Nuclear Energy" (PDF). Research Report 9. p. 1.
- "IPCC Working Group III – Mitigation of Climate Change, Annex II I: Technology - specific cost and performance parameters" (PDF). IPCC. 2014. p. 10. Archived from the original (PDF) on 16 June 2014. Retrieved 1 August 2014.
- "IPCC Working Group III – Mitigation of Climate Change, Annex II Metrics and Methodology. pg 37 to 40,41" (PDF). Archived from the original (PDF) on 29 September 2014.
- Begoña Guezuraga, Rudolf Zauner, Werner Pölz, Life cycle assessment of two different 2 MW class wind turbines, Renewable Energy 37 (2012) 37-44, p 37. doi:10.1016/j.renene.2011.05.008
- Why Australia needs wind power Archived 1 January 2007 at the Wayback Machine.
- "Wind energy Frequently Asked Questions". British Wind Energy Association. Archived from the original on 19 April 2006. Retrieved 21 April 2006.
- Gohlke, Julia M; Hrynkow, Sharon H; Portier, Christopher J (2008). "Health, Economy, and Environment: Sustainable Energy Choices for a Nation". Environmental Health Perspectives. 116 (6): A236–7. doi:10.1289/ehp.11602. PMC . PMID 18560493.
- Hamilton, Tyler (15 December 2009). "Wind Gets Clean Bill of Health". Toronto Star. Toronto. pp. B1–B2. Retrieved 16 December 2009.
- Thomas Kirchhoff (2014): Energiewende und Landschaftsästhetik. Versachlichung ästhetischer Bewertungen von Energieanlagen durch Bezugnahme auf drei intersubjektive Landschaftsideale, in: Naturschutz und Landschaftsplanung 46 (1), 10-16.
- United Nations Development Programme - Environment and Energy for Sustainable Development
- Discussion of environmental cost of providing renewable energy - Environment impact of renewable energy technologies | <urn:uuid:161214a0-1de0-4415-aa69-4c4174bbbca4> | 3.171875 | 3,721 | Knowledge Article | Science & Tech. | 43.662985 | 95,631,005 |
|Debugging with GDB|
You may want to specify executable and core dump file names. The usual way to do this is at start-up time, using the arguments to gdb's start-up commands (see Getting In and Out of gdb).
Occasionally it is necessary to change to a different file during a
gdb session. Or you may run gdb and forget to
specify a file you want to use. Or you are debugging a remote target
gdbserver (see file). In these situations the gdb commands to specify
new files are useful.
runcommand. If you do not specify a directory and the file is not found in the gdb working directory, gdb uses the environment variable
PATHas a list of directories to search, just as the shell does when looking for a program to run. You can change the value of this variable, for both gdb and your program, using the
You can load unlinked object .o files into gdb using
file command. You will not be able to “run” an object
file, but you can disassemble functions and inspect variables. Also,
if the underlying BFD functionality supports it, you could use
gdb -write to patch object files using this technique. Note
that gdb can neither interpret nor modify relocations in this
case, so branches and some initialized variables will appear to go to
the wrong place. But this feature is still handy from time to time.
filewith no argument makes gdb discard any information it has on both executable file and the symbol table.
exec-file[ filename ]
PATHif necessary to locate your program. Omitting filename means to discard information on the executable file.
symbol-file[ filename ]
PATHis searched when necessary. Use the
filecommand to get both symbol table and program to run from the same file.
symbol-file with no argument clears out gdb information on your
program's symbol table.
symbol-file command causes gdb to forget the contents of
some breakpoints and auto-display expressions. This is because they may
contain pointers to the internal data recording symbols and data types,
which are part of the old symbol table data being discarded inside
symbol-file does not repeat if you press <RET> again after
executing it once.
When gdb is configured for a particular environment, it understands debugging information in whatever format is the standard generated for that environment; you may use either a gnu compiler, or other compilers that adhere to the local conventions. Best results are usually obtained from gnu compilers; for example, using gcc you can generate debugging information for optimized code.
For most kinds of object files, with the exception of old SVR3 systems
using COFF, the
symbol-file command does not normally read the
symbol table in full right away. Instead, it scans the symbol table
quickly to find which source files and which symbols are present. The
details are read later, one source file at a time, as they are needed.
The purpose of this two-stage reading strategy is to make gdb
start up faster. For the most part, it is invisible except for
occasional pauses while the symbol table details for a particular source
file are being read. (The
set verbose command can turn these
pauses into messages if desired. See Optional Warnings and Messages.)
We have not implemented the two-stage strategy for COFF yet. When the
symbol table is stored in COFF format,
symbol-file reads the
symbol table data in full right away. Note that “stabs-in-COFF”
still does the two-stage strategy, since the debug info is actually
in stabs format.
core-file with no argument specifies that no core file is
to be used.
Note that the core file is ignored when your program is actually running
under gdb. So, if you have been running your program and you
wish to debug a core file instead, you must kill the subprocess in which
the program is running. To do this, use the
(see Killing the Child Process).
add-symbol-filefilename address [
add-symbol-filecommand reads additional symbol table information from the file filename. You would use this command when filename has been dynamically loaded (by some other means) into the program that is running. The address should give the memory address at which the file has been loaded; gdb cannot figure this out for itself. You can additionally specify an arbitrary number of ‘-s section address’ pairs, to give an explicit section name and base address for that section. You can specify any address as an expression.
The symbol table of the file filename is added to the symbol table
originally read with the
symbol-file command. You can use the
add-symbol-file command any number of times; the new symbol data
thus read is kept in addition to the old.
Changes can be reverted using the command
Although filename is typically a shared library file, an executable file, or some other object file which has been fully relocated for loading into a process, you can also load symbolic information from relocatable .o files, as long as:
Some embedded operating systems, like Sun Chorus and VxWorks, can load
relocatable files into an already running program; such systems
typically make the requirements above easy to meet. However, it's
important to recognize that many native systems use complex link
.linkonce section factoring and C++ constructor table
assembly, for example) that make the requirements difficult to meet. In
general, one cannot assume that using
add-symbol-file to read a
relocatable object file's symbolic information will have the same effect
as linking the relocatable object file into the program in the normal
add-symbol-file does not repeat if you press <RET> after using it.
add-symbol-filecommand. The file to remove can be identified by its filename or by an address that lies within the boundaries of this symbol file in memory. Example:
(gdb) add-symbol-file /home/user/gdb/mylib.so 0x7ffff7ff9480 add symbol table from file "/home/user/gdb/mylib.so" at .text_addr = 0x7ffff7ff9480 (y or n) y Reading symbols from /home/user/gdb/mylib.so...done. (gdb) remove-symbol-file -a 0x7ffff7ff9480 Remove symbol table from file "/home/user/gdb/mylib.so"? (y or n) y (gdb)
remove-symbol-file does not repeat if you press <RET> after using it.
syscall DSOinto each process's address space; this DSO provides kernel-specific code for some system calls. The argument can be any expression whose evaluation yields the address of the file's shared object file header. For this command to work, you must have used
exec-filecommands in advance.
add-shared-symbol-files command can currently be used only
in the Cygwin build of gdb on MS-Windows OS, where it is an
alias for the
dll-symbols command (see Cygwin Native).
gdb automatically looks for shared libraries, however if
gdb does not find yours, you can invoke
add-shared-symbol-files. It takes one argument: the shared
library's file name.
assf is a shorthand alias for
sectioncommand changes the base address of the named section of the exec file to addr. This can be used if the exec file does not contain section addresses, (such as in the
a.outformat), or when the addresses specified in the file itself are wrong. Each section must be changed separately. The
info filescommand, described below, lists all the sections and their addresses.
info targetare synonymous; both print the current target (see Specifying a Debugging Target), including the names of the executable and core dump files currently in use by gdb, and the files from which symbols were loaded. The command
help targetlists all possible targets rather than current ones.
maint info sections
maint info sections. In addition to the section information displayed by
info files, this command displays the flags and file offset of each section in the executable and core dump files. In addition,
maint info sectionsprovides the following command options (which may be arbitrarily combined):
set trust-readonly-sections on
The default is off.
set trust-readonly-sections off
All file-specifying commands allow both absolute and relative file names as arguments. gdb always converts the file name to an absolute file name and remembers it that way.
On MS-Windows gdb must be linked with the Expat library to support shared libraries. See Expat.
gdb automatically loads symbol definitions from shared libraries
when you use the
run command, or when you examine a core file.
(Before you issue the
run command, gdb does not understand
references to a function in a shared library, however—unless you are
debugging a core file).
On HP-UX, if the program loads a library explicitly, gdb
automatically loads the symbols at the time of the
There are times, however, when you may wish to not automatically load symbol definitions from shared libraries, such as when they are particularly large or there are many of them.
on, symbols from all shared object libraries will be loaded automatically when the inferior begins execution, you attach to an independently started inferior, or when the dynamic linker informs gdb that a new library has been loaded. If mode is
off, symbols must be loaded manually, using the
sharedlibrarycommand. The default value is
If your program uses lots of shared libraries with debug info that takes large amounts of memory, you can decrease the gdb memory footprint by preventing it from automatically loading the symbols from shared libraries. To that end, type set auto-solib-add off before running the inferior, then load each library whose debug symbols you do need with sharedlibrary regexp, where regexp is a regular expression that matches the libraries whose symbols you want to be loaded.
run. If regex is omitted all shared libraries required by your program are loaded.
Sometimes you may wish that gdb stops and gives you control
when any of shared library events happen. The best way to do this is
catch load and
catch unload (see Set Catchpoints).
gdb also supports the the
command for this. This command exists for historical reasons. It is
less useful than setting a catchpoint, because it does not allow for
conditions or commands as a catchpoint does.
Shared libraries are also supported in many cross or remote debugging configurations. gdb needs to have access to the target's libraries; this can be accomplished either by providing copies of the libraries on the host system, or by asking gdb to automatically retrieve the libraries from the target. If copies of the target libraries are provided, they need to be the same as the target libraries, although the copies on the target can be stripped as long as the copies on the host are not.
For remote debugging, you need to tell gdb where the target libraries are, so that it can load the correct copies—otherwise, it may try to load the host's libraries. gdb has two variables to specify the search directories for target libraries.
set sysrootto find shared libraries, they need to be laid out in the same way that they are on the target, with e.g. a /lib and /usr/lib hierarchy under path.
If path starts with the sequence remote:, gdb will
retrieve the target libraries from the remote system. This is only
supported when using a remote target that supports the
command (see Sending files to a remote system).
The part of path following the initial remote:
(if present) is used as system root prefix on the remote file system.
For targets with an MS-DOS based filesystem, such as MS-Windows and SymbianOS, gdb tries prefixing a few variants of the target absolute file name with path. But first, on Unix hosts, gdb converts all backslash directory separators into forward slashes, because the backslash is not a directory separator on Unix:
c:\foo\bar.dll ⇒ c:/foo/bar.dll
Then, gdb attempts prefixing the target file name with path, and looks for the resulting file name in the host file system:
c:/foo/bar.dll ⇒ /path/to/sysroot/c:/foo/bar.dll
If that does not find the shared library, gdb tries removing the ‘:’ character from the drive spec, both for convenience, and, for the case of the host file system not supporting file names with colons:
c:/foo/bar.dll ⇒ /path/to/sysroot/c/foo/bar.dll
This makes it possible to have a system root that mirrors a target with more than one drive. E.g., you may want to setup your local copies of the target system shared libraries like so (note ‘c’ vs ‘z’):
/path/to/sysroot/c/sys/bin/foo.dll /path/to/sysroot/c/sys/bin/bar.dll /path/to/sysroot/z/sys/bin/bar.dll
and point the system root at /path/to/sysroot, so that gdb can find the correct copies of both c:\sys\bin\foo.dll, and z:\sys\bin\bar.dll.
If that still does not find the shared library, gdb tries removing the whole drive spec from the target file name:
c:/foo/bar.dll ⇒ /path/to/sysroot/foo/bar.dll
This last lookup makes it possible to not care about the drive name, if you don't want or need to.
set solib-absolute-prefix command is an alias for
You can set the default system root by using the configure-time ‘--with-sysroot’ option. If the system root is inside gdb's configured binary prefix (set with ‘--prefix’ or ‘--exec-prefix’), then the default system root will be updated automatically if the installed gdb is moved to a new location.
Shared library file names as reported by the target system may not
make sense as is on the system gdb is running on. For
example, when remote debugging a target that has MS-DOS based file
system semantics, from a Unix host, the target may be reporting to
gdb a list of loaded shared libraries with file names such as
c:\Windows\kernel32.dll. On Unix hosts, there's no concept of
drive letters, so the ‘c:\’ prefix is not normally understood as
indicating an absolute file name, and neither is the backslash
normally considered a directory separator character. In that case,
the native file system would interpret this whole absolute file name
as a relative file name with no directory components. This would make
it impossible to point gdb at a copy of the remote target's
shared libraries on the host using
set sysroot, and impractical
set solib-search-path. Setting
dos-based tells gdb
to interpret such file names similarly to how the target would, and to
map them to file names valid on gdb's native file system
semantics. The value of kind can be
"auto", in addition
to one of the supported file system kinds. In that case, gdb
tries to determine the appropriate file system variant based on the
current target's operating system (see Configuring the Current ABI). The supported file system settings are:
When processing file names provided by the user, gdb
frequently needs to compare them to the file names recorded in the
program's debug info. Normally, gdb compares just the
base names of the files as strings, which is reasonably fast
even for very large programs. (The base name of a file is the last
portion of its name, after stripping all the leading directories.)
This shortcut in comparison is based upon the assumption that files
cannot have more than one base name. This is usually true, but
references to files that use symlinks or similar filesystem
facilities violate that assumption. If your program records files
using such facilities, or if you provide file names to gdb
using symlinks etc., you can set
true to instruct gdb to completely canonicalize each
pair of file names it needs to compare. This will make file-name
comparisons accurate, but at a price of a significant slowdown.
If you want to specify a local system root using a directory that happens to be named remote:, you need to use some equivalent variant of the name like ./remote:. | <urn:uuid:ff2fd449-0d68-4aa2-950f-83e563fba2af> | 2.6875 | 3,650 | Documentation | Software Dev. | 50.138308 | 95,631,016 |
It was not until years later that Bauer and his team were able to confirm that this object was a supernova. Clues from a spectrum obtained by ESO’s Very Large Telescope led the team to start the real detective work of searching through data from 18 different telescopes, both ground- and space-based, nearly all of which existed. Because this object was found in an interesting nearby galaxy, the public archives of these telescopes contained abundant observations.
The data show that SN 1996cr is among the brightest supernovae ever seen in radio and X-rays. It also bears many striking similarities to the famous supernova SN 1987A, which occurred in a neighbouring galaxy only 160 000 light-years from Earth.
“This supernova appears to be a wild cousin of SN 1987A,” says Bauer. “The two look alike in many ways, except this newer supernova is intrinsically a thousand times brighter in radio and X-rays.”
Visible-light images from the archives of the Anglo-Australian Telescope in Australia show that SN 1996cr exploded sometime between 28 February 1995 and 15 March 1996, but it is the only one of the five nearest supernovae of the last 25 years that was not seen shortly after the explosion.
Other major X-ray observatories in orbit like ROSAT and ASCA did not detect SN 1996cr, but since it was first detected by Chandra in 2001 it has become steadily brighter. Previously, SN 1987A was the only known supernova with an X-ray output that increased over time.
“It’s a bit of a coup to find SN 1996cr like this, and we could never have nailed it without the serendipitous data taken by all of these telescopes. We've truly entered a new era of ‘internet astronomy’,” said Bauer.
The combined data, in conjunction with theoretical work, have led the team to develop a model for the explosion. Before the parent star exploded, it cleared out a large cavity in the surrounding gas, either via a strong wind or from an outburst from the star late in its life. So the blast wave from the explosion itself could expand relatively unimpeded into this cavity. Once the blast wave hit the dense material surrounding SN1996cr, the impact caused the system to glow brightly in X-ray and radio emission. The X-ray and radio emission from SN 1987A is probably fainter because the surrounding material is less compact.
Astronomers think that both SN 1987A and SN 1996cr show evidence for these pre-explosion clear-outs by a star doomed to explode. Having two nearby examples suggests that this type of activity could be relatively common during the death of massive stars.
“Not only does our work suggest that SN 1987A isn’t as unusual as previously thought, but it also teaches us more about the tremendous upheavals that massive stars can undergo over their lifetimes,” said co-author Vikram Dwarkadas of the University of Chicago.
Henri Boffin | 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.
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20.07.2018 | Materials Sciences | <urn:uuid:2990e910-82a0-4fd2-82d8-0767b86b9168> | 3.328125 | 1,205 | Content Listing | Science & Tech. | 46.143055 | 95,631,032 |
Decreasing WidthPro Problems > Math > Geometry > Rectangles and Squares
The area of a rectangle is 288 square inches. If the width is decreased by 20, the new area would be 168. What is the perimeter of the original rectangle?
SolutionIn order to make it feasible for teachers to use these problems in their classwork, no solutions are publicly visible, so students cannot simply look up the answers. If you would like to view the solutions to these problems, you must have a Virtual Classroom subscription.
The length of a rectangle is 3 times its width. If the length is decreased by 3, and the width is increased by 11, the resulting figure is a square. What is the area of the original rectangle?
Two rectangles are overlapped on a corner as shown in the image. The overlapped region is a square. The length of one rectangle is twice the length of the other, and its width is half the width of the other.
If we consider the rectangles as a single geometric figure, its outer perimeter is 768 units, and its area is 8415 square units.
The perimeter of the first rectangle is 312 units.
Find the area of the overlapped square, given that all the side measures are integers.
In the diagram shown, the blue square and the yellow rectangle share a side.
The area of yellow rectangle is 96 square units more than the area of the blue square.
The combined area of the two figures is 384 square units.
How long is the common side of the rectangle and the square?
Square X has sides of length n units. Its interior is filled with squares of side length 1 unit.
These same unit squares could be taken from the interior of X and placed along the edges of square Y, so that all the unit squares are on the exterior of square Y, with a single edge of each unit square against an edge of Y, and no part of any edge of Y does not touch a unit square.
There are two more squares, which are non-overlapping: H and K. The length of a side of K is 4 less than the length of a side of H. All the unit squares could be placed on the interior of squares H and K, with at least one edge of each unit square against an edge of either H or K, and such that no part of any edge of H or K does not touch a unit square.
If the sides of square H are 5 units shorter than the sides of square Y, how many unit squares are there?
The perimeter of a rectangle is 124 inches. The length is 2 feet more than the width. What is the area of the rectangle?
The area of a rectangle is 192 square feet, and its perimeter is 54 feet. How many feet long is the diagonal of the rectangle?
Farmer Dell has a field that is shaped like a letter L, and he wants to divide it into three parts, as shown below:
The region in the upper right corner has a perimeter of 140 yards. The regions in the upper left corner and the lower right corner both have perimeters of 180 yards. He originally had enough fencing to enclose the two top regions, and now he needs an extra 140 feet of fencing to complete the job.
What is the total area of his field?
I want to build a room which has width 6 feet less than twice its length. The area of the room will be 216 square feet. What is the width of the room?
The height of a rectangle is decreased by two inches, and the width is increased by three inches. The new rectangle’s area is 14 square inches more than the original rectangle’s area. If the dimensions of the rectangle are integers, what is the smallest possible area of the original rectangle? | <urn:uuid:ef6dbe21-255c-4c19-a448-9307a0e02b12> | 3.53125 | 781 | Tutorial | Science & Tech. | 68.243358 | 95,631,034 |