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A hydrothermal vent is a fissure in a planet's surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart at spreading centers, ocean basins, and hotspots. Hydrothermal vents exist because the earth is both geologically active and has large amounts of water on its surface and within its crust. Common land types include hot springs, fumaroles and geysers. Under the sea, hydrothermal vents may form features called black smokers. Relative to the majority of the deep sea, the areas around submarine hydrothermal vents are biologically more productive, often hosting complex communities fueled by the chemicals dissolved in the vent fluids. Chemosynthetic bacteria and archaea form the base of the food chain, supporting diverse organisms, including giant tube worms, clams, limpets and shrimp. Active hydrothermal vents are believed to exist on Jupiter's moon Europa, and Saturn's moon Enceladus, and it is speculated that ancient hydrothermal vents once existed on Mars.
Hydrothermal vents in the deep ocean typically form along the mid-ocean ridges, such as the East Pacific Rise and the Mid-Atlantic Ridge. These are locations where two tectonic plates are diverging and new crust is being formed.
The water that issues from seafloor hydrothermal vents consists mostly of sea water drawn into the hydrothermal system close to the volcanic edifice through faults and porous sediments or volcanic strata, plus some magmatic water released by the upwelling magma. In terrestrial hydrothermal systems, the majority of water circulated within the fumarole and geyser systems is meteoric water plus ground water that has percolated down into the thermal system from the surface, but it also commonly contains some portion of metamorphic water, magmatic water, and sedimentary formational brine that is released by the magma. The proportion of each varies from location to location.
In contrast to the approximately 2 °C (36 °F) ambient water temperature at these depths, water emerges from these vents at temperatures ranging from 60 °C (140 °F) up to as high as 464 °C (867 °F). Due to the high hydrostatic pressure at these depths, water may exist in either its liquid form or as a supercritical fluid at such temperatures. The critical point of (pure) water is 375 °C (707 °F) at a pressure of 218 atmospheres. However, introducing salinity into the fluid raises the critical point to higher temperatures and pressures. The critical point of seawater (3.2 wt. % NaCl) is 407 °C (765 °F) and 298.5 bars, corresponding to a depth of ~2,960 m (9,710 ft) below sea level. Accordingly, if a hydrothermal fluid with a salinity of 3.2 wt. % NaCl vents above 407 °C (765 °F) and 298.5 bars, it is supercritical. Furthermore, the salinity of vent fluids have been shown to vary widely due to phase separation in the crust. The critical point for lower salinity fluids is at lower temperature and pressure conditions than that for seawater, but higher than that for pure water. For example, a vent fluid with a 2.24 wt. % NaCl salinity has the critical point at 400 °C (752 °F) and 280.5 bars. Thus, water emerging from the hottest parts of some hydrothermal vents can be a supercritical fluid, possessing physical properties between those of a gas and those of a liquid.
Examples of supercritical venting are found at several sites. Sister Peak (Comfortless Cove Hydrothermal Field, phase-separated, vapor-type fluids. Sustained venting was not found to be supercritical but a brief injection of 464 °C (867 °F) was well above supercritical conditions. A nearby site, Turtle Pits, was found to vent low salinity fluid at 407 °C (765 °F), which is above the critical point of the fluid at that salinity. A vent site in the Cayman Trough named Beebe, which is the world's deepest known hydrothermal site at ~5,000 m (16,000 ft) below sea level, has shown sustained supercritical venting at 401 °C (754 °F) and 2.3 wt% NaCl., depth 2,996 m or 9,829 ft) vents low salinity
Although supercritical conditions have been observed at several sites, it is not yet known what significance, if any, supercritical venting has in terms of hydrothermal circulation, mineral deposit formation, geochemical fluxes or biological activity.
The initial stages of a vent chimney begin with the deposition of the mineral anhydrite. Sulfides of copper, iron, and zinc then precipitate in the chimney gaps, making it less porous over the course of time. Vent growths on the order of 30 cm (1 ft) per day have been recorded. An April 2007 exploration of the deep-sea vents off the coast of Fiji found those vents to be a significant source of dissolved iron.
Black smokers and white smokersEdit
Some hydrothermal vents form roughly cylindrical chimney structures. These form from minerals that are dissolved in the vent fluid. When the superheated water contacts the near-freezing sea water, the minerals precipitate out to form particles which add to the height of the stacks. Some of these chimney structures can reach heights of 60 m. An example of such a towering vent was "Godzilla", a structure on the Pacific Ocean deep seafloor near Oregon that rose to 40 m before it fell over in 1996.
A black smoker or deep sea vent is a type of hydrothermal vent found on the seabed, typically in the bathyal zone (with largest frequency in depths from 2500 m to 3000 m), but also in lesser depths as well as deeper in abyssal zone. They appear as black, chimney-like structures that emit a butt of black material. Black smokers typically emit particles with high levels of sulfur-bearing minerals, or sulfides. Black smokers are formed in fields hundreds of meters wide when superheated water from below Earth's crust comes through the ocean floor (water may attain temperatures above 400 °C). This water is rich in dissolved minerals from the crust, most notably sulfides. When it comes in contact with cold ocean water, many minerals precipitate, forming a black, chimney-like structure around each vent. The deposited metal sulfides can become massive sulfide ore deposits in time. Some black smokers on the Azores portion of the Mid Atlantic Ridge are extremely rich in metal content, such as Rainbow with 24,000 μM concentrations of iron.
Black smokers were first discovered in 1979 on the East Pacific Rise by scientists from Scripps Institution of Oceanography. They were observed using the deep submergence vehicle ALVIN from the Woods Hole Oceanographic Institution. Now, black smokers are known to exist in the Atlantic and Pacific Oceans, at an average depth of 2100 metres. The most northerly black smokers are a cluster of five named Loki's Castle, discovered in 2008 by scientists from the University of Bergen at 73°N, on the Mid-Atlantic Ridge between Greenland and Norway. These black smokers are of interest as they are in a more stable area of the Earth's crust, where tectonic forces are less and consequently fields of hydrothermal vents are less common. The world's deepest known black smokers are located in the Cayman Trough, 5,000 m (3.1 miles) below the ocean's surface.
White smoker vents emit lighter-hued minerals, such as those containing barium, calcium and silicon. These vents also tend to have lower-temperature plumes probably because they are generally distant from their heat source.
Black and white smokers may coexist in the same hydrothermal field, but they generally represent proximal and distal vents to the main upflow zone, respectively. However, white smokers correspond mostly to waning stages of such hydrothermal fields, as magmatic heat sources become progressively more distant from the source (due to magma crystallization) and hydrothermal fluids become dominated by seawater instead of magmatic water. Mineralizing fluids from this type of vents are rich in calcium and they form dominantly sulfate-rich (i.e., barite and anhydrite) and carbonate deposits.
Life has traditionally been seen as driven by energy from the sun, but deep-sea organisms have no access to sunlight, so they must depend on nutrients found in the dusty chemical deposits and hydrothermal fluids in which they live. Previously, benthic oceanographers assumed that vent organisms were dependent on marine snow, as deep-sea organisms are. This would leave them dependent on plant life and thus the sun. Some hydrothermal vent organisms do consume this "rain", but with only such a system, life forms would be very sparse. Compared to the surrounding sea floor, however, hydrothermal vent zones have a density of organisms 10,000 to 100,000 times greater.
Hydrothermal vent communities are able to sustain such vast amounts of life because vent organisms depend on chemosynthetic bacteria for food. The water from the hydrothermal vent is rich in dissolved minerals and supports a large population of chemoautotrophic bacteria. These bacteria use sulfur compounds, particularly hydrogen sulfide, a chemical highly toxic to most known organisms, to produce organic material through the process of chemosynthesis.
The ecosystem so formed is reliant upon the continued existence of the hydrothermal vent field as the primary source of energy, which differs from most surface life on Earth, which is based on solar energy. However, although it is often said that these communities exist independently of the sun, some of the organisms are actually dependent upon oxygen produced by photosynthetic organisms, while others are anaerobic.
The chemosynthetic bacteria grow into a thick mat which attracts other organisms, such as amphipods and copepods, which graze upon the bacteria directly. Larger organisms, such as snails, shrimp, crabs, tube worms, fish (especially eelpout, cutthroat eel, ophidiiforms and Symphurus thermophilus), and octopuses (notably Vulcanoctopus hydrothermalis), form a food chain of predator and prey relationships above the primary consumers. The main families of organisms found around seafloor vents are annelids, pogonophorans, gastropods, and crustaceans, with large bivalves, vestimentiferan worms, and "eyeless" shrimp making up the bulk of nonmicrobial organisms.
Siboglinid tube worms, which may grow to over 2 m (6.6 ft) tall in the largest species, often form an important part of the community around a hydrothermal vent. They have no mouth or digestive tract, and like parasitic worms, absorb nutrients produced by the bacteria in their tissues. About 285 billion bacteria are found per ounce of tubeworm tissue. Tubeworms have red plumes which contain hemoglobin. Hemoglobin combines with hydrogen sulfide and transfers it to the bacteria living inside the worm. In return, the bacteria nourish the worm with carbon compounds. Two of the species that inhabit a hydrothermal vent are Tevnia jerichonana, and Riftia pachyptila. One discovered community, dubbed "Eel City", consists predominantly of the eel Dysommina rugosa. Though eels are not uncommon, invertebrates typically dominate hydrothermal vents. Eel City is located near Nafanua volcanic cone, American Samoa.
In 1993, already more than 100 gastropod species were known to occur in hydrothermal vents. Over 300 new species have been discovered at hydrothermal vents, many of them "sister species" to others found in geographically separated vent areas. It has been proposed that before the North American plate overrode the mid-ocean ridge, there was a single biogeographic vent region found in the eastern Pacific. The subsequent barrier to travel began the evolutionary divergence of species in different locations. The examples of convergent evolution seen between distinct hydrothermal vents is seen as major support for the theory of natural selection and of evolution as a whole.
Although life is very sparse at these depths, black smokers are the centers of entire ecosystems. Sunlight is nonexistent, so many organisms – such as archaea and extremophiles – convert the heat, methane, and sulfur compounds provided by black smokers into energy through a process called chemosynthesis. More complex life forms, such as clams and tubeworms, feed on these organisms. The organisms at the base of the food chain also deposit minerals into the base of the black smoker, therefore completing the life cycle.
A species of phototrophic bacterium has been found living near a black smoker off the coast of Mexico at a depth of 2,500 m (8,200 ft). No sunlight penetrates that far into the waters. Instead, the bacteria, part of the Chlorobiaceae family, use the faint glow from the black smoker for photosynthesis. This is the first organism discovered in nature to exclusively use a light other than sunlight for photosynthesis.
New and unusual species are constantly being discovered in the neighborhood of black smokers. The Pompeii worm Alvinella pompejana, which is capable of withstanding temperatures up to 80 °C (176 °F), was found in the 1980s, and a scaly-foot gastropod Chrysomallon squamiferum in 2001 during an expedition to the Indian Ocean's Kairei hydrothermal vent field. The latter uses iron sulfides (pyrite and greigite) for the structure of its dermal sclerites (hardened body parts), instead of calcium carbonate. The extreme pressure of 2500 m of water (approximately 25 megapascals or 250 atmospheres) is thought to play a role in stabilizing iron sulfide for biological purposes. This armor plating probably serves as a defense against the venomous radula (teeth) of predatory snails in that community.
In March 2017, researchers reported evidence of possibly the oldest forms of life on Earth. Putative fossilized microorganisms were discovered in hydrothermal vent precipitates in the Nuvvuagittuq Belt of Quebec, Canada, that may have lived as early as 4.280 billion years ago, not long after the oceans formed 4.4 billion years ago, and not long after the formation of the Earth 4.54 billion years ago.
Although the discovery of hydrothermal vents is a relatively recent event in the history of science, the importance of this discovery has given rise to, and supported, new biological and bio-atmospheric theories.
The Deep Hot BiosphereEdit
At the beginning of his 1992 paper The Deep Hot Biosphere, Thomas Gold referred to ocean vents in support of his theory that the lower levels of the earth are rich in living biological material that finds its way to the surface. He further expanded his ideas in the book The Deep Hot Biosphere.
An article on abiogenic hydrocarbon production in the February 2008 issue of Science journal used data from experiments at the Lost City hydrothermal field to report how the abiotic synthesis of low molecular mass hydrocarbons from mantle derived carbon dioxide may occur in the presence of ultramafic rocks, water, and moderate amounts of heat.
Hydrothermal origin of lifeEdit
The chemical and thermal dynamics in hydrothermal vents makes such environments highly suitable thermodynamically for chemical evolution processes to take place. Therefore, thermal energy flux is a permanent agent and contributed to the evolution of the planet, including prebiotic chemistry.
Günter Wächtershäuser proposed the iron-sulfur world theory and suggested that life might have originated at hydrothermal vents. Wächtershäuser proposed that an early form of metabolism predated genetics. By metabolism he meant a cycle of chemical reactions that release energy in a form that can be harnessed by other processes.
It has been proposed that amino acid synthesis could have occurred deep in the Earth's crust and that these amino acids were subsequently shot up along with hydrothermal fluids into cooler waters, where lower temperatures and the presence of clay minerals would have fostered the formation of peptides and protocells. This is an attractive hypothesis because of the abundance of CH4 (methane) and NH3 (ammonia) present in hydrothermal vent regions, a condition that was not provided by the Earth's primitive atmosphere. A major limitation to this hypothesis is the lack of stability of organic molecules at high temperatures, but some have suggested that life would have originated outside of the zones of highest temperature. There are numerous species of extremophiles and other organisms currently living immediately around deep-sea vents, suggesting that this is indeed a possible scenario.
Experimental research and computing modeling indicate that the surfaces of mineral particles inside hydrothermal vents have similar catalytic properties to enzymes and are able to create simple organic molecules, such as methanol (CH3OH) and formic acid (HCO2H), out of the dissolved CO2 in the water.
Discovery and explorationEdit
In 1949, a deep water survey reported anomalously hot brines in the central portion of the Red Sea. Later work in the 1960s confirmed the presence of hot, 60 °C (140 °F), saline brines and associated metalliferous muds. The hot solutions were emanating from an active subseafloor rift. The highly saline character of the waters was not hospitable to living organisms. The brines and associated muds are currently under investigation as a source of mineable precious and base metals.
In June 1976, scientists from Scripps Institution of Oceanography obtained the first evidence for submarine hydrothermal vents along the Galápagos Rift, a spur of the East Pacific Rise, on the Pleiades II expedition, using the Deep-Tow seafloor imaging system. In 1977, the first scientific papers on hydrothermal vents were published by scientists from Scripps Institution of Oceanography; research scientist Peter Lonsdale published photographs taken from deep-towed cameras, and PhD student Kathleen Crane published maps and temperature anomaly data. Transponders were deployed at the site, which was nicknamed "Clam-bake", to enable an expedition to return the following year for direct observations with the DSV ALVIN.
Chemosynthetic ecosystems surrounding the Galápagos Rift submarine hydrothermal vents were first directly observed in 1977, when a group of marine geologists funded by the National Science Foundation returned to the Clambake sites. The principal investigator for the submersible study was Jack Corliss of Oregon State University. Corliss and Tjeerd van Andel from Stanford University observed and sampled the vents and their ecosystem on February 17, 1977, while diving in the DSV ALVIN, a research submersible operated by Woods Hole Oceanographic Institution (WHOI). Other scientists on the research cruise included Richard (Dick) Von Herzen and Robert Ballard of WHOI, Jack Dymond and Louis Gordon of Oregon State University, John Edmond and Tanya Atwater of the Massachusetts Institute of Technology, Dave Williams of the U.S. Geological Survey, and Kathleen Crane of Scripps Institution of Oceanography. This team published their observations of the vents, organisms, and the composition of the vent fluids in the journal Science. In 1979, a team of biologists led by J. Frederick Grassle, at the time at WHOI, returned to the same location to investigate the biological communities discovered two year earlier.
High temperature hydrothermal vents, the “black smokers”, were discovered in spring 1979 by a team from the Scripps Institution of Oceanography using the submersible ALVIN. The RISE expedition explored the East Pacific Rise at 21° N with the goals of testing geophysical mapping of the sea floor with the ALVIN and finding another hydrothermal field beyond the Galápagos Rift vents. The expedition was led by Fred Spiess and Ken Macdonald and included participants from the U.S., Mexico and France. The dive region was selected based on the discovery of sea floor mounds of sulfide minerals by the French CYAMEX expedition in 1978. Prior to dive operations, expedition member Robert Ballard located near-bottom water temperature anomalies using a deeply towed instrument package. The first dive was targeted at one of those anomalies. On Easter Sunday April 15, 1979 during a dive of ALVIN to 2600 meters, Roger Larson and Bruce Luyendyk found a hydrothermal vent field with a biological community similar to the Galápagos vents. On a subsequent dive, William Normark and Thierry Juteau discovered the high temperature vents emitting black mineral particle jets from chimneys; the black smokers. Following this Macdonald and Jim Aiken rigged a temperature probe to ALVIN to measure the water temperature at the black smoker vents. This observed the highest temperatures then recorded at deep sea hydrothermal vents (380±30 °C). Analysis of black smoker material and the chimneys that fed them revealed that iron sulfide precipitates are the common minerals in the “smoke” and walls of the chimneys.
In 2005, Neptune Resources NL, a mineral exploration company, applied for and was granted 35,000 km² of exploration rights over the Kermadec Arc in New Zealand's Exclusive Economic Zone to explore for seafloor massive sulfide deposits, a potential new source of lead-zinc-copper sulfides formed from modern hydrothermal vent fields. The discovery of a vent in the Pacific Ocean offshore of Costa Rica, named the Medusa hydrothermal vent field (after the serpent-haired Medusa of Greek mythology), was announced in April 2007. The Ashadze hydrothermal field (13°N on the Mid-Atlantic Ridge, elevation -4200 m) was the deepest known high-temperature hydrothermal field until 2010, when a hydrothermal plume emanating from the Beebe site ( , elevation -5000 m) was detected by a group of scientists from NASA Jet Propulsion Laboratory and Woods Hole Oceanographic Institution. This site is located on the 110 km long, ultraslow spreading Mid-Cayman Rise within the Cayman Trough. In early 2013, the deepest known hydrothermal vents were discovered in the Caribbean at a depth of almost 5,000 metres (16,000 ft).
Hydrothermal vents and other geothermal manifestations are currently being explored in the Bahía de Concepción, Baja California Sur, Mexico.
Hydrothermal vents tend to be distributed along the Earth's plate boundaries, although they may also be found at intra-plate locations such as hotspot volcanoes. As of 2009 there were approximately 500 known active submarine hydrothermal vent fields, with about half visually observed at the seafloor and the other half suspected from water column indicators and/or seafloor deposits. The InterRidge program office hosts a global database for the locations of known active submarine hydrothermal vent fields.
Hydrothermal vents, in some instances, have led to the formation of exploitable mineral resources via deposition of seafloor massive sulfide deposits. The Mount Isa orebody located in Queensland, Australia, is an excellent example. Many hydrothermal vents are rich in cobalt, gold, copper, and rare earth metals essential for electronic components. Hydrothermal venting on the Archean seafloor is considered to have formed Algoma-type banded iron formations which have been a source of iron ore.
Recently, mineral exploration companies, driven by the elevated price activity in the base metals sector during the mid-2000s, have turned their attention to extraction of mineral resources from hydrothermal fields on the seafloor. Significant cost reductions are, in theory, possible.
Two companies are currently engaged in the late stages of commencing to mine seafloor massive sulfides. Nautilus Minerals is in the advanced stages of commencing extraction from its Solwarra deposit, in the Bismarck Archipelago, and Neptune Minerals is at an earlier stage with its Rumble II West deposit, located on the Kermadec Arc, near the Kermadec Islands. Both companies are proposing using modified existing technology. Nautilus Minerals, in partnership with Placer Dome (now part of Barrick Gold), succeeded in 2006 in returning over 10 metric tons of mined SMS to the surface using modified drum cutters mounted on an ROV, a world first. Neptune Minerals in 2007 succeeded in recovering SMS sediment samples using a modified oil industry suction pump mounted on an ROV, also a world first.
Potential seafloor mining has environmental impacts including dust plumes from mining machinery affecting filter-feeding organisms, collapsing or reopening vents, methane clathrate release, or even sub-oceanic land slides. A large amount of work is currently being engaged in by both the above-mentioned companies to ensure that potential environmental impacts of seafloor mining are well understood and control measures are implemented, before exploitation commences.
Attempts have been made in the past to exploit minerals from the seafloor. The 1960s and 70s saw a great deal of activity (and expenditure) in the recovery of manganese nodules from the abyssal plains, with varying degrees of success. This does demonstrate however that recovery of minerals from the seafloor is possible, and has been possible for some time. Mining of manganese nodules served as a cover story for the elaborate attempt in 1974 by the CIA to raise the sunken Soviet submarine K-129, using the Glomar Explorer, a ship purpose built for the task by Howard Hughes. The operation was known as Project Azorian, and the cover story of seafloor mining of manganese nodules may have served as the impetus to propel other companies to make the attempt.
The conservation of hydrothermal vents has been the subject of sometimes heated discussion in the oceanographic community for the last 20 years. It has been pointed out that it may be that those causing the most damage to these fairly rare habitats are scientists. There have been attempts to forge agreements over the behaviour of scientists investigating vent sites but although there is an agreed code of practice there is as yet no formal international and legally binding agreement.
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- Rogers, Alex D.; Tyler, Paul A.; Connelly, Douglas P.; Copley, Jon T.; James, Rachael; Larter, Robert D.; Linse, Katrin; Mills, Rachel A.; Garabato, Alfredo Naveira; Pancost, Richard D.; Pearce, David A.; Polunin, Nicholas V. C.; German, Christopher R.; Shank, Timothy; Boersch-Supan, Philipp H.; Alker, Belinda J.; Aquilina, Alfred; Bennett, Sarah A.; Clarke, Andrew; Dinley, Robert J. J.; Graham, Alastair G. C.; Green, Darryl R. H.; Hawkes, Jeffrey A.; Hepburn, Laura; Hilario, Ana; Huvenne, Veerle A. I.; Marsh, Leigh; Ramirez-Llodra, Eva; Reid, William D. K.; Roterman, Christopher N.; Sweeting, Christopher J.; Thatje, Sven; Zwirglmaier, Katrin (2012). "The Discovery of New Deep-Sea Hydrothermal Vent Communities in the Southern Ocean and Implications for Biogeography". PLOS Biology. 10 (1): –1001234. doi:10.1371/journal.pbio.1001234. ISSN 1545-7885.
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- Anaerobic respiration on tellurate and other metalloids in bacteria from hydrothermal vent fields in the eastern pacific ocean
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|Wikimedia Commons has media related to Hydrothermal vents.|
- Ocean Explorer (www.oceanexplorer.noaa.gov) - Public outreach site for explorations sponsored by the Office of Ocean Exploration.
- Hydrothermal Vents Video - The Smithsonian Institution's Ocean Portal
- Vent geochemistry
- a good overview of hydrothermal vent biology, published in 2006 (PDF)
- Images of Hydrothermal Vents in Indian Ocean- Released by National Science Foundation
- How to Build a Hydrothermal Vent Chimney
- NOAA, Ocean Explorer YouTube Channel | <urn:uuid:f28c2b6c-9d5f-418c-a230-327b69b05037> | 4.1875 | 10,606 | Knowledge Article | Science & Tech. | 60.526423 | 95,500,328 |
From Alaska to Amazonia: First global maps of traits that drive vegetation growth
Detailed global maps of key traits in higher plants have been made available for the first time, thanks to work led by researchers from the University of Minnesota's (UMN) College of Food, Agriculture and Natural Resource Sciences (CFANS).
Based on measurements of 45,000 individual plants from 3,680 species, and using high-tech statistical mapping protocols, the team created global maps of plant traits including leaf nitrogen concentration, leaf phosphorus concentration, and specific leaf area (a measure of area displayed to intercept light per unit investment in leaf biomass). These maps, with more than 50,000 pixels, show surprisingly large local variation in trait values that could significantly impact future carbon cycle calculations produced by Earth System models (ESMs). The plant traits mapped in the study are critical for photosynthesis and foliar respiration and serve as input to the ESMs. Incorporating this local variability of plant traits in the ESMs will lead to more accurate modeling of carbon cycle feedbacks.
"The scarcity of field measurements presents a major roadblock in creating high resolution global maps of plant traits," said Ethan Butler, co-lead author and postdoctoral associate in the Department of Forest Resources at UMN's College of Food, Agricultural and Natural Resource Sciences (CFANS). "This work advances previous trait mapping endeavors by leveraging the largest to-date global plant trait database, TRY, which is three-fold larger than any used before."
According to Peter Reich, the project leader, "Current ESMs represent variation in plant life using crude averages of trait values of plants; a model might be as simplistic as assuming all leaves in Amazonia or Alaska are identical. The new maps reveal that local diversity is substantial; ignoring this fact is problematic. Incorporating data from these maps into the EMSs will lead to improved carbon cycle models."
"Despite having an enhanced number of field measurements, the geographical coverage of TRY is still limited with little or no data for much of the tropics, large swaths of Central Asia, Russia, South Asia and much of the Arctic," said co-lead author Abhi Datta, formerly a PhD student in the Division of Biostatistics at UMN. "Subsequently, sophisticated statistical approaches were used to extrapolate plant trait values using a combination of climate, soil and spatial information. The resulting maps provide a complete characterization of how traits vary within and among over 50,000 50 km x 50-km cells across the entire vegetated land surface."
The new findings were published in the Proceedings of the National Academy of Sciences. The study was conducted by a multi-disciplinary team of researchers spanning many institutions across the globe. The lead authors were Butler and Datta, currently an assistant professor in the Department of Biostatistics, Johns Hopkins University Bloomberg School of Public Health. Other UMN co-authors include Arindam Banerjee and Farideh Fazayeli, Department of Computer Science and Engineering; and Habacuc Flores-Moreno, Ming Chen, Kirk R. Wythers, and Peter B. Reich, Department of Forest Resources.
About University of Minnesota College of Food, Agricultural and Natural Resource Sciences
The University of Minnesota College of Food, Agricultural and Natural Resource Sciences (CFANS) brings science-driven innovators together to discover hands-on solutions to global challenges. With 10 research and outreach centers across Minnesota, the Minnesota Landscape Arboretum, and the Bell Museum of Natural History, CFANS offer unparalleled experiential learning opportunities for students and the community. For more information, visit cfans.umn.edu.
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New Online Course Makes Living on Mars a Mouse Click Away
Science & Tech| | By Robin Milling
NASA predicts we could be living on Mars by the 2030’s, so why put off the inevitable? Living on Earth is easy with the whole oxygen thing in our atmosphere. Now a new university program will teach you how you can live on Mars. With the click of a mouse you can be at home in your pajamas learning all you need to know about inhabiting Mars with a new free online course given by Monash University in Melbourne. Developed by Australian astrophysicist Jasmina Lazendic-Galloway and chemistry professor Tina Overton, the course “How to Survive on Mars: The Science Behind Human Exploration of Mars” will run over four weeks, three hours per week.
Already 1,500 people have signed up for the course beginning on October 24, 2016. Living on the red planet seems to be an idea that’s not so foreign anymore. Tesla and SpaceX founder Elon Musk has been planning his escape for years, developing all the gadgets and technology that’s needed to send people to Mars by 2025. Recently, filmmaker Werner Herzog boldly asked him for a ticket to ride to Mars on his Red Dragon capsule in his newest documentary, Lo And Behold. On August 28, a year-long mission ended when six crew members happily emerged from their simulated Mars habitat on the slopes of Mauna Loa on the Big Island of Hawaii. The University of Hawaii at Manoa’s fourth Hawaii Space Exploration Analog and Simulation (HI-SEAS) project had the crew living in isolation in a Mars-like environment for 365 days. Mashable reported the online Mars course was inspired by the ladies’ love of Andy Weir’s bestseller, The Martian, which became a 2015 award-winning film starring Matt Damon. They respected that the scientists were real problem solvers, and their mission is to bring the basics of Mars living to the common man and woman. Think, Mars For Dummies. The introductory course features how to live in space without air, the ability to grow food and how to find a water supply. At the course’s completion students will be able to “apply basic science to explore possible ways of producing water, oxygen, food and energy on Mars.” In the inimitable questioning words of the late David Bowie, “Is There Life On Mars?” We won’t have to wait light years to find out.
15 Wives & Girlfriends Of The Richest Men In The World
They have more net wealth than some small countries. They earned it with infallible business instincts and an unbroken drive to succeed. They have a passion for activism. People say ...
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We have already, in Section 9.5, met the notion of an abelian (or commutative) group with examples. Although this chapter is self-contained, the reader will find it helpful to read 9.5 again. The basic notion which we discuss in this chapter is that of a group, and an abelian group is then just a group in which the group operation is written as addition and is commutative (see G4 below). In fact, the notion of a group plays a fundamental role in algebra and geometry and an important role in the calculus and mathematical analysis. For example, the theory of groups virtually arose (in the hands of Galois, Abel, and others) out of the attempt to understand why equations of degree ≤4 could be solved by standard methods, whereas those methods failed for equations of degree ≥5. For the history of this successful attack on a very natural and classical problem the reader is referred to one of E. T. Bell’s books ( is probably the most attractive reference); for an account of the Galois theory of equations, the reader may consult Postnikov , the relevant chapter of Birkhoff-MacLane , or the more sophisticated text by Artin.
KeywordsAbelian Group Group Operation Normal Subgroup Cyclic Group Quotient Group
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Scientists at Heriot-Watt University have cracked the genetic code of the marine bacteria that helped ‘eat’ the oil spilled from the Deepwater Horizon disaster, information that could aid clean-up efforts for the next major spill.
Dr Tony Gutierrez was in the US at the time of the disaster and was able to perform experiments with samples from oil-contaminated waters of the Gulf of Mexico shortly after the Deepwater Horizon spill occurred – samples that contained key species of bacteria that fed on the oil.
Experiments with the samples revealed that certain bacteria had thrived on the oil that gushed into the Gulf, by devouring the oil as a preferred food source.
In a paper published in Nature Microbiology, Dr Gutierrez and his colleagues from the University of Texas and University of North Carolina at Chapel Hill reveal the genetic pathways these bacteria use to consume the oil, what conditions they thrive in, what oil hydrocarbons they can eat, and how they work in concert during an oil spill.
“Oil is a very complex fluid that contains thousands of different types of hydrocarbon chemicals, many of which are toxic and difficult to break down. But some of these bacteria can.
Dr Tony Gutierrez, an Associate Professor of Microbiology at Heriot-Watt University, said:
“Understanding which bacteria are important to breaking down oil could help lead to the design of emergency response plans that are more effective and environmentally friendly for combatting a major spill.
“We knew that certain bacteria will respond to and thrive during an oil spill and helped break down oil, but we didn’t know how this was coordinated.
“By reconstructing the genomes of these bacteria, we’ve discovered the pathways they use to breakdown the different types of hydrocarbon chemicals in oil, including some of the highly toxic ones, and the way the bacteria work as a community to degrade the oil.
“Different bacteria have different appetites for different hydrocarbons, but they can work beautifully in concert together to clean up polluted water.”
The findings from this UK and US collaboration also reveal an ability of these bacteria to move towards oil droplets and to use scarce nutrients, suggesting that these microbes are like sentinels in the ocean that are well-adapted to respond quickly to the influx of oil in the event of a spill.
The team also identified the bacteria that work best at different depths in the Gulf during the Deepwater Horizon spill. Oceanospirillales, for example, degraded alkanes in the deepwater oil plume, whereas Rhodospiralles and Cycloclasticus were responsible for degrading polycyclic aromatic hydrocarbons (PAHs), which are recognised as some of the most toxic chemicals in oil.
Dr Tony Gutierrez said:
“Following an oil spill, dispersants are commonly used to break up the oil into very small droplets, making it easier for the bacteria to break it down.
“Our findings show that some of the bacteria that responded to the spill in the Gulf are also able to degrade dispersants, potentially rendering them ineffective after they have done their job.
“Future oil spills are pretty much a certainty. This new information provides evidence that the incredibly diverse bacterial community that is ever present and living in the ocean stands at the ready, like an army of soldiers, to help degrade oil in the event of a spill. The hope is that our findings will allow us to exploit their oil-degrading potential on a wider scale, such as through more effective bioremediation strategies.”
Dr Gutierrez is currently working to understand the diversity and abilities of oil-degrading bacteria in UK waters where future oil spills might occur, with a view to designing effective bioremediation solutions, including evaluating the effectiveness of using chemical dispersants.
Adapted from a press release by Louise Mulhall
Read the article online at: https://www.oilfieldtechnology.com/offshore-and-subsea/10052016/oil-hungry-bacteria-could-clean-up-the-next-big-oil-spill/ | <urn:uuid:1ff94227-e459-4e16-8f79-5d1022d08e7a> | 3.859375 | 849 | News Article | Science & Tech. | 24.470271 | 95,500,371 |
|ECHINODERMATA : OPHIURIDA : Amphiuridae||STARFISH, SEA URCHINS, ETC.|
Description: A medium-sized brittle star with very long arms which lives buried in sand. The dorsal and ventral surfaces of the disc are covered in scales. Those of the ventral surface and the edge of the disc bear small tubercles. There are 8-10 short conical arm spines and 2 tentacle scales. Disc to 13mm, arms 15x disc diameter.
Habitat: This brittle star burrows in clean sand from low water mark to 40m, commoner in shallow water. Often associated with Echinocardium cordatum.
Distribution: South and west coasts of the British Isles, probably also on North Sea coasts.
Similar Species: Larger and coarser than Amphiura species, none of which have tubercles on their disc scales. Amphiura chiajei is most similar but never has more than six arm spines and has smooth ventral and marginal disc scales.
Key Identification Features:
Distribution Map from NBN: Interactive map : National Biodiversity Network mapping facility, data for UK.
WoRMS: Species record : World Register of Marine Species.
|Picton, B.E. & Morrow, C.C. (2016). Acrocnida brachiata (Montagu, 1804). [In] Encyclopedia of Marine Life of Britain and Ireland. |
http://www.habitas.org.uk/marinelife/species.asp?item=ZB2850 Accessed on 2018-07-16
|Copyright © National Museums of Northern Ireland, 2002-2015| | <urn:uuid:a60d2063-9de2-47c5-a7c3-e7ce12b60fb4> | 3.359375 | 357 | Knowledge Article | Science & Tech. | 54.328116 | 95,500,395 |
1 year ago
Scientists just discovered massive landforms, called eskers, underneath the ice in Antarctica that could be helping carve up the polar ice.
Researchers from Université libre de Bruxelles in Belgium and the Bavarian Academy of Sciences in Germany found large ridge-like protrusions jutting into the ice flow under Dronning Maud Land, Antarctica.
The findings, published in the scientific journal Nature Communications, suggest the landforms under the Baudouin Ice Shelf could have major implications for the South Pole’s stability.
Some eskers as tall as the Eiffel Tower, according to the study, which was released on Science Alert.
Scientists have known for some time that landforms could develop underneath ice sheet through a cycle evaporation and sediment precipitation.
The Scandinavian Ice Sheet, believed to be one of the largest glaciers on the planet when it existed 2.5 million years ago, created large eskers that can be seen in Sweden today. Researchers say the landforms are five times that size of those formed by the Scandinavian Ice Sheet. | <urn:uuid:3c7b422a-e0a5-4d54-898d-abf8716527da> | 4.03125 | 224 | News Article | Science & Tech. | 32.98625 | 95,500,396 |
Favored Sequencing Method for Measuring Microbial Biodiversity is Not as Accurate as Once Thought
News Aug 02, 2017 | Original story from American Museum of Natural History
Part of the research team traveling on the Amazon River © M. Lemke
Next-generation sequencing—the ability to sequence millions or billions of small fragments of DNA in parallel—has revolutionized the biological sciences, playing an essential role in everything from locating mutations that cause human disease to determining how a newly discovered animal fits into the tree of life. But a study published in the journal Scientific Reports reveals that a favored sequencing method for measuring microbial biodiversity is not as accurate as once thought.
The research team, led by scientists from the American Museum of Natural History, the City University of New York (CUNY), Weill Cornell Medicine, Universidade Estadual de Maringá, Instituto Cesumar de Ciȇncia, Tecnologia e Inovação, and the University of Illinois Springfield, compared two next-generation sequencing techniques – called amplicon and shotgun – on water samples from four of Brazil’s major river floodplain systems. Less than 50 percent of phyla—a category for a very broad group of related organisms—identified via amplicon sequencing were recovered from shotgun sequencing, challenging the dogma that shotgun recovers more diversity than amplicon-based approaches. Amplicon sequencing also revealed about 27 percent more families.
“As an example of the potential impact of our finding, you can think about the phyla Cnidaria, which contains all of the world’s anemones, corals, and jellyfish,” said senior author Mercer R. Brugler, a research associate in the Museum’s Division of Invertebrate Zoology and an assistant professor at NYC College of Technology, CUNY. “One method would find a representative from this group and the other would not. Phyla are huge groups that are completely missing from the shotgun sequencing data.”
With amplicon, the same gene (16S ribosomal RNA in this case) is sequenced from every sample, while DNA fragments are randomly sequenced when working with a shorgun technique. Although amplicon has been the traditional workhorse for studies on microbial life, the spike in human microbiome research inspired many scientists to switch to shotgun, which is cheaper and generates more genetic information. Previous human microbiome studies comparing the two techniques have also shown that shotgun produces equivalent, if not better, results. So the researchers involved in this Brazilian water study were surprised when they found something very different.
“After our earlier publication on these samples, we switched from amplicon to shotgun, with the intention of simply getting larger sample sizes,” said lead author Michael Tessler, a recent graduate of the Museum’s Richard Gilder Graduate School. “We just happened to compare the two methods because we had the data, so why not? We thought the shotgun data were at least going to be equal, if not rock the socks off of the amplicon data.”
They thought that because of the huge disparity in the amount of genetic data each method generates: amplicon gave them about 346,000 fragments of useable DNA, while shotgun resulted in about 575 million reads. Yet amplicon revealed more than twice the number of phyla.
“It’s like a fisherman with a single fishing rod catching more fish than a commercial trawler,” Tessler said.
So why did amplicon sequencing, which is thought by many as an aging technique, outperform shotgun in this case? Shotgun sequences random fragments of DNA, not one consistent gene, so it requires researchers to have a strong database they can use to match the sequences to an organism. If the data for that organism do not exist, you only get the closest match, or no match at all. For this study, which looks at fairly understudied freshwater bacteria, the database is extremely weak.
“The takehome message is that if you’re working in a more remote system, you need to be testing your methods,” Tessler said.
Brugler added: “Studies to date that have used shotgun alone to infer microbial diversity estimates should be viewed cautiously, as they are likely underestimating true diversity.”
This article has been republished from materials provided by American Museum of Natural History. Note: material may have been edited for length and content. For further information, please contact the cited source.
Tessler, M., Neumann, J. S., Afshinnekoo, E., Pineda, M., Hersch, R., Velho, L. F., . . . Brugler, M. R. (2017). Large-scale differences in microbial biodiversity discovery between 16S amplicon and shotgun sequencing. Scientific Reports, 7(1). doi:10.1038/s41598-017-06665-3
Fetal Gene Therapy Prevents Lethal Neurodegenerative DiseaseNews
Researchers have successfully prevented the development of a fatal neurodegenerative disorder, Gaucher disease, using fetal gene therapy, in mice. The study highlights the potential of using this approach to combat lethal neurodegenerative diseases affecting newborns.READ MORE
Natural Product Could Lead to New Class of Commercial HerbicideNews
By looking for microorganism's protective shield, specifically the genes that can make it, a team discovered a new and potentially highly effective type of weed killer. This finding could lead to the first new class of commercial herbicides in more than 30 years.READ MORE | <urn:uuid:65938069-3ea5-428b-9b20-fc829a76c6a6> | 3.046875 | 1,163 | Truncated | Science & Tech. | 33.79724 | 95,500,417 |
No twilight within the courts of the Sun.
The Sun's rim dips; the stars rush out:
At one stride comes the dark;
With far-heard whisper, o'er the sea,
Off shot the spectre-bark.
At the rising of the Moon,
We listened and looked sideways up!
Fear at my heart, as at a cup,
My life-blood seemed to sip!
The stars were dim, and thick the night,
The steerman's face by his lamp gleamed white;
From the sails the dew did drip—
Till clomb above the eastern bar
The hornéd Moon, with one bright star
Within the nether tip.
-Samuel Taylor Coleridge, The Rime of the Ancient Mariner
While pursuing my doctorate in experimental astrophysics, in London, I would sometimes visit the map room at the British Museum. I'd look at the ancient maps, with coastlines that were recognizable, but distorted and out of proportion. Some areas were imagined to be populated by terrifying monsters, or even left blank, because cartographers of the time had insufficient information to do better. Over time, as more information was observed or extrapolated, maps became more accurate, and were able to cover more area, piecing together our picture of the world like a puzzle, a little bit at a time. And as we did this, piece by piece, we learned more about our place in the world.
Here’s an example of an old map, showing western Europe’s 1502 limited understanding of what southeast Asia looks like. The map is charmingly inaccurate.
You Are Here
When we describe the location of something on Earth, we might use landmarks and directions, or provide a street address. Or we can use a two-dimensional coordinate system, specifying the first coordinate as this far away from one axis, and the next coordinate as that far away from a second axis (running in a direction not aligned to the first axis).
We commonly use the coordinate system. One coordinate describes latitude (how far north or south we are), with the equator representing zero degrees latitude. The other describes longitude (how far east or west), with the prime meridian representing zero degrees longitude running through Greenwich in the United Kingdom. Visits to Greenwich for me always included a visit to the Royal Greenwich Observatory, a stroll through Greenwich Park, and a visit to the National Maritime Museum.
Today we can readily determine our geographic location in terms of latitude and longitude, by using GPS. But astonishing as it may be to the legions of teenagers out there, this information wasn't always as close as a glance at our phone. In the days before GPS and smartphones, people could figure out latitude from looking at how high the Sun was in the sky at noontime, and factoring in the day of the year and the corresponding position of the Earth along its orbit around the Sun. Perhaps you've already noticed for yourself that you can estimate your latitude with some intuitive observations: how high the sun goes in the sky; what time of year it is; how long the daylight lasts; and where on the horizon the sun rises and sets.
Longitude was harder, and for centuries, a practicable way to measure it precisely eluded even some of history's greatest minds (including that of Galileo). In the end, the method settled on was for seafarers to carry two clocks, one set to the time at a port of reference, and a second one, which was reset to noon every day when the Sun was at its highest point in the sky. The longitude of the ship could then be calculated from the difference in time between the two clocks—so long as both clocks ran accurately. (Readers familiar with Einstein's special theory of relativity may wonder whether his thinking found inspiration from this practice.) To learn more about the fascinating history of longitude and navigation, I recommend Dava Sobel's Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time.
Even today, people at sea learn and practice old celestial navigation methods as a backup to GPS. When I was doing atmospheric, oceanographic and entomological research from the M/V OCEANIC, I saw some beautiful sextants (sextants measure the exact angle of something in the sky compared to the horizon) on the bridge of the ship. The crew explained they had to keep up their training in traditional navigation techniques, just in case the ship's GPS had problems.
Astronomical Coordinate Systems
Like the explorers and thinkers who developed our terrestrial grid system of latitude and longitude, astronomers also use a grid system to define location—albeit with different axes, considering that they're describing the locations of objects on the sky rather than on Earth. Think how difficult it would be to explain where exactly something appears on the sky without using a grid system. All you could ever hope to do is give someone a general idea where to look, and hope they notice the same object you have in mind. In fact, in astronomy, we have different coordinate systems from which to choose, depending on how we want to describe the location of something. But there are natural coordinate systems that make intuitive sense to us as observers on Earth, and which we therefore might prefer to use.
In every grid system used to observe and map the sky, we start by imagining the sky as a spherical dome and project the coordinate axes outward onto the dome. One commonly-used grid system (the Equatorial Celestial Reference System) uses axes on which we measure positions called declination and right ascension; the intersection of these two coordinates (expressed in terms hours, arc-minutes, and arc-seconds) is where we find a particular object. The axes originate from the Earth's orbit around the Sun (defining what we call the ecliptic) and from the Earth's own rotation: that is, the poles and equator, from which we define north and south celestial poles and a celestial equator. In this system, declination can be thought of as similar to the concept of latitude (how high up is the object?), and right ascension can be thought of as similar to longitude (how far in this or that lateral direction?). Declination and right ascension, although somewhat akin to latitude and longitude, are not exactly the same as those concepts. If you want to learn more about them, a good introductory description can be found in Part 4 of H.A. Rey’s The Stars.
What Astrometry Measures
Astrometry seeks to make a highly precise two-dimensional map of the sky, and so it leaves out the dimension we think of as depth. We don't use astrometry to measure how far away things are from us, or how far away they might be from each other in that third dimension. To make the two-dimensional map, astrometry starts by imagining the sky as projected onto the inside of a spherical shell with a constant radius, as if Earth were at the center of a giant planetarium. Then, looking outward from Earth, astrometry measures how far apart the astronomical objects are from each other on the inside of the sphere. We call this the "separation on the sky" between two astronomical objects as we see them through our telescope on Earth.
If you've seen the night sky from the northern hemisphere, then you're probably familiar with the constellation Cassiopeia—the one that looks like a warped letter "W." (Anytime we talk about constellations, it's useful to remember the stars making up a constellation in all likelihood aren't actually near one another; they just look that way to us, on Earth. To alien astronomers on their home planet, those same stars would look very different.) The two brightest stars in Cassiopeia, as seen from Earth, are shown below. From other types of astronomical observations, as we’ll explain in a future blog entry, we’ve learned the brightest star in Cassiopeia is four times farther from Earth than the next brightest star. But that's completely independent of exactly what position each of those stars occupies on the dome of the night sky, or how far apart those same two stars appear from one another on that dome. On the inside of the dome, the two stars have certain locations, and a certain separation, both of which we can measure and watch over time to see how they change.
Why Astrometry Matters
You may wonder why astrometry is important to science. The simple answer is we want to know what's out there and where to find it. But beyond that, unless we have a good understanding of exactly what objects are located precisely where in the sky, and how they're moving, it's hard to learn the properties of those objects or know for sure if we're looking at something new. Conversely, when we do know those details, then we can learn surprising things about the cosmos that open doors to exciting new discoveries.
Astrometry has helped us understand things even about the makeup of our own Solar System, like finding the (former) planet Pluto. When astronomers were tracking Neptune's orbit around our Sun, they noticed a difference from what was expected. They wondered if maybe another, as-yet-undiscovered planetary body was out there, and used the orbital wobble of Neptune to locate that mysterious planetary body: Pluto. (Pluto is, of course, no longer considered a planet. At Caltech, I had the pleasure of studying planetary science with Professor Mike Brown, author of How I Killed Pluto and Why It had It Coming, and one of the researchers looking for a new Planet 9 out there.)
Astrometry has also been key to unlocking the secrets of exoplanets—including planets that might harbor life—black holes, and dark matter. One way astronomers can tell a planet is going around another star is by noticing its effects on the star's movement. And they can detect black holes by noticing their gravitational effects on the motions of nearby objects. In fact, we discovered a supermassive black hole at the center of our own Milky Way galaxy by carefully tracking the orbits of stars near the galactic center. Similarly, this kind of observation was also what led to the idea of dark matter: no one has ever actually seen dark matter, but something out there has mass, which affects the movements of other objects in ways we've observed through astrometry—and so we called that something dark matter. All of these things require that astronomers be able to notice and track small changes in the positions of the objects in the sky. In other words, they require astrometry.
Now that you're familiar with what astrometry is and why it's important, you'll probably want to know more about how we go about making these precise measurements. In Part 2 of this article, we'll look at some of the interesting challenges of astrometry and how TMT is preparing to meet them.
Samuel Taylor Coleridge, “The Rime of the Ancient Mariner”, annotated edition with an introduction and notes by Martin Gardner ; illustrated by Gustave Doré. Prometheus: New York (2003). See in particular pp.66-67 for elaboration on the extract included in this blog entry.
Andrew K. Johnston, Carlene E. Stephens, Paul E. Ceruzzi, and Roger D. Connor, “Time and Navigation: The Untold Story of Getting from Here to There”. Smithsonian Books: Washington, D.C. (2015)
H.A. Rey, “The Stars”. Houghton Mifflin Harcourt: Boston (1982)
Peter Barber, Ed., “The Map Book”. Walker & Company: New York (2005)
Dava Sobel, “Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time”. Walker & Company: New York (1995)
Many thanks to my colleague Matthias Schöck, TMT System Scientist, for helping with this blog entry.
Sharper Focus, Part 2 - How TMT’s Adaptive Optics Will Work | <urn:uuid:d07bbbe3-592f-4f5e-aa0c-c4513a8feb43> | 2.84375 | 2,518 | Personal Blog | Science & Tech. | 46.323153 | 95,500,418 |
M27 is a planetary nebula located around 1250 ly away in the constellation of Vulpecula. It shines at magnitude 7.5 meaning it is visible in binoculars on a dark, clear night.
The term planetary nebula comes from times when optical assistance was insufficient to distinguish this type of object from a distant planet. They are formed when a red giant star runs out of nuclear fuel; the star's outer layers are pushed out into space and the central star becomes a white dwarf. The ultra-violet radiation from this star illuminates the remnants of the star.
Find The Dumbbell Nebula | <urn:uuid:bea3bc77-5e33-494f-82fc-f4cebc877376> | 3.265625 | 126 | Knowledge Article | Science & Tech. | 51.068235 | 95,500,448 |
Can you work out the arrangement of the digits in the square so that the given products are correct? The numbers 1 - 9 may be used once and once only.
Can you order the digits from 1-3 to make a number which is divisible by 3 so when the last digit is removed it becomes a 2-figure number divisible by 2, and so on?
There is a clock-face where the numbers have become all mixed up. Can you find out where all the numbers have got to from these ten statements?
The planet of Vuvv has seven moons. Can you work out how long it is between each super-eclipse?
Can you fill in this table square? The numbers 2 -12 were used to generate it with just one number used twice.
How many different shaped boxes can you design for 36 sweets in one layer? Can you arrange the sweets so that no sweets of the same colour are next to each other in any direction?
Suppose we allow ourselves to use three numbers less than 10 and multiply them together. How many different products can you find? How do you know you've got them all?
In the planet system of Octa the planets are arranged in the shape of an octahedron. How many different routes could be taken to get from Planet A to Planet Zargon?
There are 4 jugs which hold 9 litres, 7 litres, 4 litres and 2 litres. Find a way to pour 9 litres of drink from one jug to another until you are left with exactly 3 litres in three of the jugs.
This challenge is to design different step arrangements, which must go along a distance of 6 on the steps and must end up at 6 high.
In this challenge, buckets come in five different sizes. If you choose some buckets, can you investigate the different ways in which they can be filled?
This problem is based on the story of the Pied Piper of Hamelin. Investigate the different numbers of people and rats there could have been if you know how many legs there are altogether!
In a square in which the houses are evenly spaced, numbers 3 and 10 are opposite each other. What is the smallest and what is the largest possible number of houses in the square?
On a digital clock showing 24 hour time, over a whole day, how many times does a 5 appear? Is it the same number for a 12 hour clock over a whole day?
Investigate the different ways you could split up these rooms so that you have double the number.
You cannot choose a selection of ice cream flavours that includes totally what someone has already chosen. Have a go and find all the different ways in which seven children can have ice cream.
Nina must cook some pasta for 15 minutes but she only has a 7-minute sand-timer and an 11-minute sand-timer. How can she use these timers to measure exactly 15 minutes?
There are 78 prisoners in a square cell block of twelve cells. The clever prison warder arranged them so there were 25 along each wall of the prison block. How did he do it?
Place the numbers 1 to 8 in the circles so that no consecutive numbers are joined by a line.
Ten cards are put into five envelopes so that there are two cards in each envelope. The sum of the numbers inside it is written on each envelope. What numbers could be inside the envelopes?
In a bowl there are 4 Chocolates, 3 Jellies and 5 Mints. Find a way to share the sweets between the three children so they each get the kind they like. Is there more than one way to do it?
Place eight queens on an chessboard (an 8 by 8 grid) so that none can capture any of the others.
What do you notice about the date 03.06.09? Or 08.01.09? This challenge invites you to investigate some interesting dates yourself.
Add the sum of the squares of four numbers between 10 and 20 to the sum of the squares of three numbers less than 6 to make the square of another, larger, number.
What could the half time scores have been in these Olympic hockey matches?
When intergalactic Wag Worms are born they look just like a cube. Each year they grow another cube in any direction. Find all the shapes that five-year-old Wag Worms can be.
Find all the different shapes that can be made by joining five equilateral triangles edge to edge.
On a digital 24 hour clock, at certain times, all the digits are consecutive. How many times like this are there between midnight and 7 a.m.?
Sitting around a table are three girls and three boys. Use the clues to work out were each person is sitting.
Put 10 counters in a row. Find a way to arrange the counters into five pairs, evenly spaced in a row, in just 5 moves, using the rules.
Seven friends went to a fun fair with lots of scary rides. They decided to pair up for rides until each friend had ridden once with each of the others. What was the total number rides?
Place eight dots on this diagram, so that there are only two dots on each straight line and only two dots on each circle.
Using all ten cards from 0 to 9, rearrange them to make five prime numbers. Can you find any other ways of doing it?
How could you put these three beads into bags? How many different ways can you do it? How could you record what you've done?
Can you find which shapes you need to put into the grid to make the totals at the end of each row and the bottom of each column?
How could you put eight beanbags in the hoops so that there are four in the blue hoop, five in the red and six in the yellow? Can you find all the ways of doing this?
Can you make square numbers by adding two prime numbers together?
Find the product of the numbers on the routes from A to B. Which route has the smallest product? Which the largest?
These activities lend themselves to systematic working in the sense that it helps if you have an ordered approach.
My cube has inky marks on each face. Can you find the route it has taken? What does each face look like?
Can you rearrange the biscuits on the plates so that the three biscuits on each plate are all different and there is no plate with two biscuits the same as two biscuits on another plate?
This task depends on groups working collaboratively, discussing and reasoning to agree a final product.
A merchant brings four bars of gold to a jeweller. How can the jeweller use the scales just twice to identify the lighter, fake bar?
The Vikings communicated in writing by making simple scratches on wood or stones called runes. Can you work out how their code works using the table of the alphabet?
Systematically explore the range of symmetric designs that can be created by shading parts of the motif below. Use normal square lattice paper to record your results.
Can you put plus signs in so this is true? 1 2 3 4 5 6 7 8 9 = 99 How many ways can you do it?
What is the date in February 2002 where the 8 digits are palindromic if the date is written in the British way?
This multiplication uses each of the digits 0 - 9 once and once only. Using the information given, can you replace the stars in the calculation with figures?
There are seven pots of plants in a greenhouse. They have lost their labels. Perhaps you can help re-label them.
This task, written for the National Young Mathematicians' Award 2016, focuses on 'open squares'. What would the next five open squares look like? | <urn:uuid:4417a23c-e64c-4cd2-82be-aaaffeff06c8> | 3.578125 | 1,596 | Content Listing | Science & Tech. | 71.522377 | 95,500,457 |
CORVALLIS, Ore. - A new study has found that the massive Laurentide ice sheet that covered Canada during the last ice age initially began shrinking through calving of icebergs, and then abruptly shifted into a new regime where melting on the continent took precedence, ultimately leading to the sheet's demise.
Researchers say a shift in "radiative forcing" began prior to 9,000 years ago and kicked the deglaciation into overdrive. The results are important, scientists say, because they may provide a clue to how ice sheets on Greenland and Antarctica may respond to a warming climate.
Results of the study, which was funded by the National Science Foundation with support from the National Aeronautics and Space Administration (NASA), are being published this week in Nature Geoscience.
David Ullman, a postdoctoral researcher at Oregon State University and lead author on the study, said there are two mechanisms through which ice sheets diminish - dynamically, from the jettisoning of icebergs at the fringes, or by a negative "surface mass balance," which compares the amount of snow accumulation relative to melting. When more snow accumulates than melts, the surface mass balance is positive.
When melting outpaces snow accumulation, as happened after the last glacial maximum, the surface mass balance is negative.
"What we found was that during most of the deglaciation, the surface mass balance of the Laurentide Ice Sheet was generally positive," Ullman said. "We know that the ice sheet was disappearing, so the cause must have been dynamic. But there was a shift before 9,000 years ago and the deck became stacked, as sunlight levels were high because of the Earth's orbit and CO2 increased.
"There was a switch to a new state, and the ice sheet began to melt away," he added. "Coincidentally, when melting took off, the ice sheet began pulling back from the coast and the calving of icebergs diminished. The ice sheet got hammered by surface melt, and that's what drove final deglaciation."
Ullman said the level of CO2 that helped trigger the melting of the Laurentide ice sheet was near the top of pre-industrial measurements - though much less than it is today. The solar intensity then was higher than today, he added.
"What is most interesting is that there are big shifts in the surface mass balance that occur from only very small changes in radiative forcing," said Ullman, who is in OSU's College of Earth, Ocean, and Atmospheric Sciences. "It shows just how sensitive the system is to forcing, whether it might be solar radiation or greenhouse gases."
Scientists have examined ice cores dating back some 800,000 years and have documented numerous times when increases in summer insolation took place, but not all of them resulted in deglaciation to present-day ice volumes. The reason, they say, is that there likely is a climatic threshold at which severe surface melting is triggered.
"It just might be that the ice sheet needed an added kick from something like elevated CO2 levels to get things going," Ullman said.
Click photos to see a full-size version. Right click and save image to download.
David Ullman, 541-737-4915, firstname.lastname@example.org | <urn:uuid:4f503885-e2cf-44a7-9162-ea080044a91a> | 3.703125 | 693 | News Article | Science & Tech. | 40.060396 | 95,500,470 |
At 0600 UTC on January 19, Tropical Storm Funso was located in the Mozambique Channel and about 685 miles (1,102 km) northeast of Maputo, the capital and largest city of Mozambique. Mauputo is located in the extreme southeast of Mozambique. Funso's center was near 17.3 South latitude and 40.7 East longitude. It was moving to the northwest near 5 knots (6 mph/9 kmh). Maximum sustained winds were near 35 knots (40 mph/65 kmh) making it a minimal tropical storm.
NASA's Aqua satellite captured an infrared look at the temperatures of the clouds in Tropical Cyclone Funso on Jan. 19, 2012, at 10:59 UTC (5:59 a.m. EST). The coldest cloud top temperatures and strongest thunderstorms appear in purple, and were mostly over the open waters of the Mozambique Channel. Credit: NASA JPL, Ed Olsen
Five hours later, NASA's Aqua satellite passed over Tropical Storm Funso and captured visible and infrared data for forecasters.
The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA's Aqua satellite captured a visible look at the clouds of Tropical Cyclone Funso (the eight depression in the Southern Indian Ocean this season) on January 19, 2012 at 11:03 UTC (6:03 a.m. EST).
The MODIS image showed Funso was developing a signature "comma shape" in its clouds - a sign of a strengthening tropical storm. In the image, Funso's highest, strongest thunderstorms were visible around the center of circulation. Those high clouds (powerful, towering thunderstorms) were casting shadows on the lower surrounding clouds.
At the same time, another instrument on Aqua gave forecasters important information about the cloud temperatures of Cyclone Funso. The Atmospheric Infrared Sounder (AIRS) instrument saw that the coldest cloud top temperatures and strongest thunderstorms were mostly over the open waters of the Mozambique Channel at 11:00 UTC. Funso is stretched across the Mozambique Channel from east to west, and the western-most edge of Funso was bringing some moderate rainfall over central coastal Mozambique and the eastern-most extent was raining on western Madagascar.
The forecasters at the Joint Typhoon Warning Center expect Funso to move west then loop around and strengthen just off the central Mozambique coastline. Forecasters and residents of Mozambique are watching Funso's movements closely while still cleaning up from Tropical Depression Dando.
Rob Gutro | EurekAlert!
Global study of world's beaches shows threat to protected areas
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NSF-supported researchers to present new results on hurricanes and other extreme events
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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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20.07.2018 | Materials Sciences | <urn:uuid:dd8aeb81-379d-4709-91c3-fc79350f78bb> | 2.828125 | 1,102 | Content Listing | Science & Tech. | 42.665 | 95,500,475 |
The anticipated Mars landing on Jan. 24 of the Opportunity rover will be a bit more challenging than the Spirits bounce onto the red planet earlier this month, according to a University at Buffalo geologist, but if its successful, then scientists will be able to be much bolder about selecting future Mars landing sites.
Apollinaris Patera, a volcano on the surface of Mars, could be a future landing site, says a UB planetary volcanologist, if the airbag technology proves as successful with "Opportunity" as it has been with "Spirit."
"If both of these landers survive with airbag technology, then it blows the doors wide open for future Mars landing sites with far more interesting terrain," said Tracy Gregg, Ph.D., University at Buffalo assistant professor of geology in the UB College of Arts and Sciences and a planetary volcanologist.
Gregg, who headed a national conference at UB in 1999 regarding the selection of future Mars landing sites, is chair of the geologic mapping standards committee of the NASA Planetary Cartography Working Group.
Ellen Goldbaum | University at Buffalo
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
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20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:7c153a77-7543-4d2b-a795-de103265f0ab> | 2.8125 | 798 | Content Listing | Science & Tech. | 36.974663 | 95,500,488 |
New Biosensors for Testing Water
Biologists from the University of Tübingen are part of an interdisciplinary team which has developed novel biosensors that enable pharmaceutical products to be detected more effectively in water. These sensors can measure two types of pharmaceutical substances, beta-blockers and non-steroidal anti-inflammatory drugs (NSAIDs), in real-time and in low concentrations. The research was recently published in Water Research.
As a consequence of demographic change, the consumption of medicines is increasing in industrial nations. Large amounts of pharmaceutical agents are already deposited at waste treatment facilities through waste water. As these substances usually cannot be removed effectively, surface water organisms are subjected to a cocktail of drugs. Just a few micrograms per liter are enough to cause harmful side effects in fish.
In the joint project “EffPharm” biologists, biochemists and analytical chemists are working to find a solution to the problem. The project is funded by the German Environment Agency (UBA) and coordinated by ecotoxicologist Professor Rita Triebskorn. In this context, the working group headed by Dr. Manfred Frey from the Steinbeis Innovation Center for Cell Culture Technology at the Mannheim University of Applied Sciences has succeeded in developing cell-based biosensors for two classes of drugs. These biosensors can detect the binding of such substances to their target molecules (receptors) in treated waste water in real time.
At the University of Tübingen, Professor Rita Triebskorn and Professor Heinz Köhler from the Animal Physiological Ecology working group have demonstrated these biosensors to be able to detect very low concentrations of the drugs at levels which are harmful to water organisms. Dr. Marco Scheurer from the Water Technology Center in Karlsruhe showed that the new biosensors capture a large proportion of the compounds that had previously been detected by complex and time-intensive chemical analysis.
The newly developed biosensors have many more advantages in contrast to previous approaches. After the biosensor cell lines are exposed to drugs in water samples, a fluorescence signal appears within seconds. In contrast to conventional reporter gene assays, the biosensors detect the effect of chemicals in the cell in real-time and avoid misleading information which may occur in reporter gene assays that take several hours to generate a signal. Thanks to their mechanism of action, the biosensors can detect future beta-blockers or NSAIDS without knowing their exact chemical structure.
"It would be desirable for the technology developed here to be used in monitoring programs to determine the water quality and the cleaning performance of sewage treatment plants," says Professor Rita Triebskorn. "This would close an important gap in the plausibility chain between the detection of pharmaceutical substances in water and the health effects of the organisms concerned."
Bernhard, K., Stahl, C., Martens, R., Köhler, H., Triebskorn, R., Scheurer, M., & Frey, M. (2017). Two novel real time cell-based assays quantify beta-blocker and NSAID specific effects in effluents of municipal wastewater treatment plants. Water Research, 115, 74-83. doi:10.1016/j.watres.2017.02.036
This article has been republished from materials provided by the University of Tübingen. Note: material may have been edited for length and content. For further information, please contact the cited source.
How do Forests Respond to Atmospheric Pollution?News
How forests respond to elevated nitrogen levels from atmospheric pollution is not always the same. While a forest is filtering nitrogen as expected, a higher percentage than previously seen is leaving the system again as the potent greenhouse gas nitrous oxide, say researchers.READ MORE
Gotta Sample 'Em All! Underwater Pokéball Captures Ocean LifeNews
A new device developed by Wyss Institute reseachers safely traps delicate sea creatures inside a folding polyhedral enclosure and lets them go without harm using a novel, origami-inspired design. The ultimate aim is to allow the sea creatures to be (gently) analyzed in high detail.READ MORE | <urn:uuid:8dc9b349-c174-40e9-98e7-d4bcaf998979> | 3.3125 | 859 | Truncated | Science & Tech. | 32.188194 | 95,500,491 |
- Views 1945
For nearly 30 years we have been able to predict mass coral bleaching accurately with the Goreau-Hayes Satellite SST HotSpot method (Goreau, 1990 US Senate Hearings on Climate Change; Goreau et al., 1993; Goreau & Hayes, 1994). We have routinely predicted, and confirmed, bleaching events that have never been documented by the coral list or NOAA. There were many such bleaching events last year in places that were hotter for longer than the GBR, but dive shops are now routinely concealing bleaching as “bad for business”.
In one large area of the Pacific where bleaching was certain last year, only one single dive shop would admit it had happened, but did not send photos, not one of the other dive shops would respond to a request for confirmation if bleaching was happening.
The NOAA data base and the web site that documents the HotSpot data is still up, but this may simply be an accidental oversight, as all US Government sites documenting climate are being shut down because the data contradicts the politically-motivated lie that climate change is not happening!
It is very important that other countries take the data leadership role that the US regime is now destroying, because otherwise no-one will have warning when their corals are about to bleach or die.
We can only hope that the European Union, Japan, and China take up the responsibility of real time HotSpot mapping needed to provide alerts.
If there is no database documenting coral death from heat stroke, Governments will continue to falsely say that 2 degrees C further warming is “acceptable”, they will continue to sentence coral reef ecosystems to death, and billions of people living along low lying coasts to become desperate migrants, so many that no walls will be high enough.
Below is the latest Pacific HotSpot map. In case it is the very last one that we will ever see it is important to realize that a large area of the South Pacific from the Great Barrier Reef, New Caledonia, Vanuatu, Fiji, Samoa, and Tonga is warming rapidly and now is at or just below bleaching thresholds, although of course it will take about a month at present conditions for it to be generally noticeable, sooner if it continues to warm up, as normal at the very start of the hot season.
The current rate of warming is greatest in the GBR, bleaching temperatures have been reached unusually early in the season, and the hot season in Australia has not even started yet!
Barring miraculous cooling, there may be little coral left in the GBR later this year.
Ray Hayes and I have always pointed out that it is extreme events that cause bleaching, not mean changes, and the model based predictions of bleaching, which are based on mean rates of change, which say that bleaching might be a problem in the GBR in another 50 years, have proven falsely optimistic yet again.
When lies trump truth, the new dark ages begin. | <urn:uuid:9c2d496b-8309-4473-8837-cf5042aea2b9> | 2.9375 | 613 | Personal Blog | Science & Tech. | 35.817832 | 95,500,496 |
Nutrient Contribution of Nonpoint Source Runoff in the Las Vegas Valley
A Geographic Information System (GIS) based non-point source runoff model is developed for the Las Vegas Valley, Nevada, to estimate the nutrient loads during the years 2000 and 2001. The estimated non-point source loads are compared with current waste water treatment facilities loads to determine the non-point source contribution of total phosphorus (TP), total nitrogen (TN), and total suspended solids (TSS) on a monthly and annual time scale. An innovative calibration procedure is used to estimate the pollutant concentrations for different land uses based on available water quality data at the outlet. Results indicate that the pollutant concentrations are higher for the Las Vegas Valley than previous published values for semi-arid and arid regions. The total TP and TN loads from non-point sources are approximately 15 percent and 4 percent, respectively, of the total load to the receiving water body, Lake Mead. The TP loads during wet periods approach the permitted loads from the waste water treatment plants that discharge into Las Vegas Wash. In addition, the GIS model is used to track pollutant loads in the stream channels for one of the subwatersheds. This is useful for planning the location of Best Management Practices to control nonpoint pollutant loads.
Geographic information systems; Modeling; Nonpoint source pollution; Runoff; Runoff—Management; Storm water management; Surface water hydrology; Water; Water—Pollution; Watershed management
Civil and Environmental Engineering | Construction Engineering and Management | Desert Ecology | Environmental Engineering | Environmental Sciences | Geotechnical Engineering | Natural Resources and Conservation | Structural Engineering | Water Resource Management
Use Find in Your Library, contact the author, or interlibrary loan to garner a copy of the item. Publisher policy does not allow archiving the final published version. If a post-print (author's peer-reviewed manuscript) is allowed and available, or publisher policy changes, the item will be deposited.
Piechota, T. C.
Nutrient Contribution of Nonpoint Source Runoff in the Las Vegas Valley.
Journal of the American Water Resources Association, 40(6), | <urn:uuid:4caa0d6b-b1ed-47b2-87d1-d33e278619a3> | 2.796875 | 444 | Academic Writing | Science & Tech. | 18.398246 | 95,500,498 |
Last updated on May 24, 2017 by Dotsquares
Over the past decade general development practices have drastically changed across many an industry, and it has particularly evolved in the IT sector. These days’ businesses are opting to use “Agile” methodology over the classic “Waterfall” process that we are more than familiar with. But what exactly is agile development, and why are companies thriving on this type ofmethodology?
First of all let’s go back to the beginning to why agile came about in the first place. Its manifestation came from the need to perfect the development process, after too many projects were failing during production. Professionals in the field felt that there must be an easier method of development, than the typical waterfall method that derived from the manufacturing industry. Agile became a new method that could allow experts to revisit the different stages of development at any point in time.
As an insight….
By implementing Agile methodology meant there was a specific type of Rapid Application Development. But what is the difference between Waterfall and Agile?
The Waterfall model is a sequential (non-iterative) design process, in which progress is seen as flowing steadily downwards (like a waterfall).The waterfall model maintains that one should move to a phase only when its preceding phase is reviewed and verified.
The phases of the Waterfall model includes:
1. System Engineering
4. Coding or Development
Taking a step forward & then taking steps backwards is hard, and can make changes prohibitively costly.
Agile methodology is around leveraging Iterative processes to ensure you have the focus to get your product ready.
Its four key values are around:
• People rather than processes
• Product over documentation
• Working together over Admin Paper Work
• Flexibility and agility for changes during project work
There is also a sub type of Agile development that is often used which is referred to as Scrum Agile. The Scrum process consists of Planning, a Sprint cycle which is a block of work, and the eventual closure.Scrum is based on the principles and values of The Agile Manifesto (http://agilemanifesto.org/principles.html),and has three roles:
So Scrum in effect is around the input of planning & high level design, followed by Scrum Cycle or Cycles depending on the project, till the point your product is ready for the market.
Now you know the difference between both Waterfall and Agile methodology, let’s have a look at some of the positives and negatives of both.
So as you can see although Agile has a few negative factors, it is still highly favourable for companies in the IT industry around the globe. With Agile in place you can expect to deliver rapid application development, with a solid B2C relationship, which in turn will safeguard the future of your business! | <urn:uuid:62e49dcb-2bc0-4970-847f-61ed1b5392f4> | 2.859375 | 597 | News (Org.) | Software Dev. | 33.433891 | 95,500,514 |
Neurobiologists at Duke University Medical Center have found the strongest evidence yet that monkeys show the same keen "social reflexes" that humans do -- shifting their attention in response to the direction of gaze of another individual. The researchers said their findings mean that monkeys can provide a critically important animal model of how the brain controls what humans pay attention to in social situations.
Such a model would enable scientists to better understand how processing of social attention works in the brain, and how it can go awry in such disorders as autism. Such basic studies, said the neurobiologists, could lead to better treatments for autism and better methods to teach autistic children.
The researchers, post-doctoral fellow Robert Deaner and Assistant Professor Michael Platt, reported their findings in the Sept. 16, 2003, issue of Current Biology. The research was supported by the National Institute of Mental Health and the National Eye Institute.
Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung
Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:e14f219d-ccb1-4810-ac86-a367da015f1c> | 2.859375 | 822 | Content Listing | Science & Tech. | 40.6074 | 95,500,516 |
Will Iceland's Volcano Boost Geoengineering?
By Bryan Caplan
When Mount Pinatubo erupted in 1991, I don’t think I even heard about it. But this one event depressed global temperatures by about 1 degree Fahrenheit. Given all the attention the latest volcano‘s getting, I thought the predicted effect might be comparable. Apparently not:
Cataclysmic eruptions, led by Pinatubo and
Mount Chichon in Mexico in 1982 in the 20th century, spewed so much
debris into the upper atmosphere that they cooled the planet for
months, briefly offsetting the effect of industrial heat-trapping gases.
is not like Pinatubo. So far the scale is not big enough to have a
global effect,” said Hans Olav Hygen, a climate researcher at the
Norwegian Meteorological Institute.
Still, since politics is about perceptions, not facts, it wouldn’t surprise me if the eruption gave geoengineering another boost. Your guess? | <urn:uuid:4cd3fb8a-6d68-439d-aa1c-aadb8522163e> | 3.296875 | 211 | Personal Blog | Science & Tech. | 43.768075 | 95,500,529 |
12 July 2018
The finest features
Published online 23 May 2016
Scientists invent a ‘super’ imaging technique capable of scanning the seafloor for oil deposits.
Minute details of an object are lost when reflected light (or sound) carrying the fine features emerge as evanescent waves that decay as they travel away from the object.
But a research team from King Abdullah University of Science and Technology (KAUST), Saudi Arabia, has overcome this by developing an imaging technique that can generate super-resolution images. The contraption can preserve the fine features of distant objects such as seafloor salt domes1.
“Since many of the deep oil deposits in the Gulf of Mexico cling to the sides of salt domes, this imaging technique will enhance the ability to identify the location of oil deposits beneath the salt structures,” says geologist Gerard Schuster.
Using oil company’s seismic data and sonar imaging of the seafloor, Schuster and his teammates have shown that it is possible to create super-resolution image of seismic reflectors by considering resonant multiples — repeated reflections from the same reflecting object via waves that propagate along the same wave paths.
This technique can double the image resolution of reflectors, suggesting its potential application in engineering surveys that map out safe areas for placing pipes or structures on the seafloor.
In the future, this technique could be used to detect subtle geological changes in a layer that are indicative of hydrocarbon or mineral deposits and also track fine details of a growing fetus, the researchers say.
- Guo, B. et al. Far-field super-resolution imaging of resonant multiples. Sci. Adv. http://dx.doi.org/10.1126/sciadv.1501439 (2016). | <urn:uuid:8b37e116-4ea1-4f2d-88ec-2231b565d02e> | 3.78125 | 369 | Truncated | Science & Tech. | 39.423942 | 95,500,530 |
Issue Date: May 12, 2008
Migratory birds navigate for thousands of miles, relying on Earth's magnetic field as a guide, but the precise mechanism they use to determine their position and directional information remains unresolved.
Now, a radical-chemistry-based hypothesis for how birds use Earth's magnetic field as a compass has received a boost. British and American scientists have built a chemical model that lends some credence to the radical-chemistry hypothesis of magnetoreception (Nature, DOI: 10.1038/nature06834).
Specifically, the hypothesis argues that incident light on photoreceptor proteins in a bird's retina could create radical pairs. The fate of these short-lived reaction intermediates, such as returning to a resting state or reacting to give a different radical product, could be modulated by Earth???s magnetic field and could therefore act as a magnetic field sensor or compass.
One of the biggest concerns with the radical-chemistry hypothesis has been that no radical pair reactions have been shown to be modulated by magnetic fields as weak as Earth's, says Peter J. Hore, a chemist at Oxford University. So Hore collaborated with chemists Christiane Timmel at Oxford and Devens Gust at Arizona State University to build a carotenoid-porphyrin-fullerene model system that produces radical electron pairs that are measurably affected by Earth's magnetic fields.
"We've shown for the first time that a radical pair chemical reaction can respond to a field as weak as Earth's," Hore says. "If we can do it in a lab, then perhaps animals can do it in nature—although presumably more efficiently and sensitively."
The fact that the molecule can detect Earth's magnetic field is a "big step toward the proof of principle" for the radical-chemistry model of avian magnetoreception and provides a good working model of the system, says Thorsten Ritz, a biophysicist at the University of California, Irvine.
Many researchers have postulated that radical pairs in an avian photoreceptor protein called cryptochrome could be the biological source of radical-chemistry magnetoreception. Hore's model will help establish methods for detecting magnetoreception in the protein, Ritz notes.
Conversely, Sönke Johnsen, a biologist at Duke University, is not convinced that the results on the carotenoid-porphyrin-fullerene system "have any biological relevance." Johnsen points out that the molecule can detect Earth's magnetic field only at subfreezing temperatures—about –150 °C, much colder than a bird???s body temperature, which is about 40 °C.
A more prominent hypothesis of avian magnetoreception argues that magnetite crystals found in birds??? beaks can align with Earth's magnetic field and act as directional sensors. The main challenge to the magnetite crystal hypothesis relates to transduction of the signal. Currently, no conclusive anatomical connection between magnetite and the nervous system has been established in birds.
Nevertheless, the radical-chemistry hypothesis still has a long way to go before it can compete with the magnetite-crystal-based model for support. Hore says he hopes that the carotenoid-porphyrin-fullerene model is a first tool for developing techniques to address the challenges of the radical-chemistry hypothesis and propel it toward widespread acceptance as a mechanism of avian magnetoreception.
- Chemical & Engineering News
- ISSN 0009-2347
- Copyright © American Chemical Society | <urn:uuid:8c5051d1-1237-4388-8f43-8f5a8ca6d8a7> | 4.125 | 735 | Knowledge Article | Science & Tech. | 30.228889 | 95,500,549 |
The system will be unavailable due to maintenance on Thursday July 19 from 7:00-8:30 am ET.
Terrain and Landcover Effects of the Southern Appalachian Mountains on the Low-Level Rotational Wind Fields of Supercell Thunderstorms
Prociv, Kathryn A
MetadataShow full item record
That tornadoes cannot occur in mountains due to disruptive influences of the complex terrain is a common misperception. Multiple tornadoes occur each year in mountainous environments, including the Appalachian Mountains. Copious research examines the influences of complex terrain on large severe weather systems such as multicell convective systems and squall lines, but research is lacking investigating this same relationship for smaller-scale severe weather phenomena like supercells and tornadoes. This study examines how complex terrain may have influenced the rotational low-level wind fields of fourteen supercell thunderstorms in the Appalachians. The terrain variables include elevation, land cover, slope, and aspect. Using GIS mapping techniques, the individual storm tracks were overlaid onto elevation, land cover, slope, and aspect layers; points along the storm tracks were measured to correlate storm intensities with the underlying terrain. Hypotheses predict that lower elevations, areas of shallower slopes, agricultural land covers, and terrain features with a southeasterly orientation represent terrain variables that would enhance low-level rotation in the lower levels. Results indicate that elevation has a significant impact on storm rotational intensity, especially in mountainous regions. Lower and flatter elevations augment storm rotational intensity, and higher elevations decrease storm rotational intensity. Additionally, northern and western facing slopes exhibited a negative relationship to storm intensity. A qualitative examination revealed vorticity stretching to be evident in eight of the fourteen storms; with vorticity stretching evident on both southeasterly and northwesterly slopes. Future research on appropriate scale for storm-terrain interactions could reveal even stronger relationships between topography and supercell thunderstorms.
- Masters Theses | <urn:uuid:f60db435-01a7-43cc-b657-3ec399eec378> | 3.21875 | 403 | Academic Writing | Science & Tech. | 5.983016 | 95,500,564 |
This is in continuation to the previous post, if you have not read that, I would advise you to go through that before continue reading.
I discussed about three use cases in my last post, here I will explain them in detail.
- Extracting data from a binary log file:
The binary log file is full of information, but what if you want selected info, for example:
- printing the timestamp for every event in the binary log file.
- extracting the event types of all the events occurring in the binary log file.
And any other such data from an event in real time. Below is some sample code which shows how to do that step by step.
- Connect to the available transport
// the base class for both types of transport, the term driver and transport are
// used interchangeably in code.
- For tcp transport
// An example of the uri can be mysql://neha@localhost:3306
- For file transport
// The path should be absolute like
drv=binary_log::system::create_transport("path of the binary log file");
- Common code for both transports
// This internally calls methods from libmysqlclient library
- For tcp transport
- Fetch the stream in a buffer
// In this pair object the first value will store stream buffer and second value
// will store length buffer, only one event is received at a time.
// This internally calls methods from libmysqlclient library.
- Decode the buffer and get an event object
binary_log::Binary_log_event *event; // To store the event object
// This class contains method to decode all the binary log events
event= decode.decode_event((char *) buffer_buflen.first, buffer_buflen.second,
NULL/* char array to store the error message*/, 1)
- Now that the event object is created, it can be used to extract all the information about that particular event, for example
std::cout<<”Event type ”<<event->get_event_type()<<std::endl;
std::cout<<”Data written ”<<event->header()->data_written<<std::endl;
std::cout<<”Binlog Position ”<<event->header()->log_pos<<std::endl;
You can see the complete code below.
The above example will print just one event, if you want to continue reading events, place the code for decoding and printing in a while loop, with breaking condition as per your requirement. If there are no more events left to read, an EOF message will appear in case of file transport.
- Filtering events from a Binary log file:
Imagine a case where you want to have all the queries executed on your server in a
printable format at one place may be in some file, or you want to be notified whenever a binary log file is rotated(this can be identified by Rotate event). Similar to these there can be many other use cases where you are only interested in some events and don’t want to load yourself with extra information.In the last use case we saw how we can get an event object, now to filter event we can do this:
The steps for getting the event object will be same as last example
/*And as this is real time, you can just run your application and all the queries will be printed as soon as they executed on the MySQL Server in case of a tcp transport.
Filtering query_event and printing the query for each Query_event
The type of event object is Binary_log_event which is the abstract class for all events
to extract any data which is specific to that event We will need to have the appropriate
if (event->get_event_type() == QUERY_EVENT)
std::cout<<” The Query is “<<static_cast<Query_event*>(event)->query<<std::endl;
- Building application to support heterogeneous replication in real time. Heterogeneous replication is where the two datastore participating in the replication process are different. There are multiple scenarios where this is beneficial, for example: Apache Kafka captures thedata from different streams and processes them, and imagine a scenario where we want to establish a replication system between MySQL server and Apache Kafka, so we can create an application using MySQL Binlog Events which will enable you to create a pipeline between MySQL Server and Apache Kafka, and replicate the data from MySQL to Apache Kafka in real time.
These are just some of the many places where MySQL Binlog Events can be used. This is a very generic framework so there will be many other use-cases. Let us know how you are using this library. Its always exciting to hear about the real use cases. If you have any comments or questions, please get in touch.
If you happen to find a bug, please file the bug at bugs.mysql.com.
This library is availabe at labs.mysql.com, choose MySQL Binlog Events 1.0.0 from the drop down menu.
Looking forward to the feedback.
370 total views, 2 views today | <urn:uuid:8d186f44-eef8-4d37-9695-7bc1e300238c> | 2.6875 | 1,096 | Documentation | Software Dev. | 43.902069 | 95,500,572 |
International teams of researchers, including two scientists from the University of Rochester, have been studying the location and behaviour of magma chambers on the Earth's mid-ocean ridge system—a vast chain of volcanoes along which the Earth forms new crust.
They worked in the tropical region of Afar, Ethiopia and the subarctic country of Iceland—the only places where mid-ocean ridges appear above sea level. Volcanic ridges (or "spreading centers") occur when tectonic plates "rift" or pull apart. This happens when magma (hot molten rock) injects itself into weaknesses in the brittle upper crust, erupting as lava and forming new crust upon cooling.
"These conclusions would not have been possible without the multi-disciplinary expertise of the researchers taking part in these studies," said Cynthia Ebinger, professor of geophysics at the University of Rochester.
The studies, published in Nature Geoscience, reveal new information about where magma is stored and how it moves through the geological plumbing network.
Magma chambers work like plumbing systems, channelling pressurized magma through networks of underground "pipes." Finding out where magma chambers lie and how they behave could help identify early warning signs of impending eruptions, according to the researchers.
By analyzing images taken by the European Space Agency satellite Envisat, scientists were able to measure how the ground moved before, during, and after eruptions. Also, Ebinger and Manahloh Belachew, also from the University of Rochester, operated an array of seismographs that provided the depth and detailed time control to gauge the fracturing of the earth and the flow of magma from multiple eruptions in Afar. Using these data, the international team built and tested computer models to find out how rifting occurs.
The team of scientists discovered that the ground started "uplifting" (elevating) four months before the eruption, due to new magma increasing pressure in one of the underground chambers. They hope the ground movement will prove to be precursory signals that are fundamental to predicting eruptions.
In an extensive study of eruptions in Afar and Iceland—two vastly different environments—Ebinger and Belachew found remarkable similarities, with many events occurring within a short space of time. They identified multiple magma chambers positioned horizontally and vertically, allowing magma to shoot in several directions. Earthquake patterns were used to track the migrating magma as it inflated cracks, and to map the rupture of faults above the miles of propagating magma injection zones. The combined data sets show that separate magma chambers fed single eruptions.
A sequence of eruptions in Afar from 2005 to the present is part of an unusual period of volcanic unrest in Ethiopia, and is enabling scientists to learn more about magma plumbing systems at spreading centers. Most spreading centers are about a mile under water at the bottom of the ocean, making detailed observations extremely challenging.
"Our studies in Ethiopia open the door to new discoveries of multi-tiered magma chambers along submerged mid-ocean ridges worldwide," said Ebinger. "We also found that magma movement and faulting during intense episodes create much of the characteristic rift valley topography, where narrow lowlands are found between mountain ranges."
When magma intrudes into a region it generates earthquakes, according to Belachew, a Ph.D. candidate. "The detailed relations of the earthquake sequences in both time and space allow us to track the movement of magma and associated fault rupture with unprecedented detail," he said.
Tim Wright, from the University of Leeds' School of Earth and Environment, heads the international Afar Rift Consortium. "The dramatic events we have been witnessing in Afar in the past six years are transforming our understanding of how the crust grows when tectonic plates pull apart," said Wright. "Our work in one of the hottest places on Earth is having a direct impact on our understanding of eruptions from the frozen volcanoes of Iceland."
The studies were funded by the UK Natural Environment Research Council through the Afar Rift Consortium, the National Centre for Earth Observation, the US National Science Foundation, the UK Royal Society, and the Icelandic Research Fund. Seismic instrumentation was provided by IRIS-PASSCAL and Seis-UK; GPS instrumentation by UNAVCO.
Peter Iglinski | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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:4a05cd95-7f15-4072-a692-32f3b946effb> | 4.25 | 1,477 | Content Listing | Science & Tech. | 33.676088 | 95,500,593 |
Include directive: Include directive (<%@ include %>) includes file into the JSP page at compile time. Include directive should be used if the included code is in the same page.
Include Action: Includes action (<jsp:include>) includes the output at runtime. Include action (runtime include) runs a bit slower yet it is preferred generally because it save a lot of memory of the system.
E.g: Suppose there are two pages welcome.jsp and
index.jsp and welcome.jsp includes index.jsp, index.jsp is invoked only when
welcome.jsp executes, and the output of index.jsp is inserted into
the output stream of welcome.jsp.
For example, if you want to use an include having a set of tag libraries with the taglib directive, you should use a compile-time include. If you wish to insert a standard header and footer in your page, include action will be more efficient. | <urn:uuid:88f95473-a0f9-486b-a206-e68b8e042040> | 2.84375 | 205 | Documentation | Software Dev. | 49.758651 | 95,500,601 |
A discovery by scientists at the Department of Energy's Oak Ridge National Laboratory supports a century-old theory by Albert Einstein that explains how heat moves through everything from travel mugs to engine parts.
The transfer of heat is fundamental to all materials. This new research, published in the journal Science, explored thermal insulators, which are materials that block transmission of heat.
New research about the transfer of heat--fundamental to all materials--suggests that in thermal insulators, heat is conveyed by atomic vibrations and by random hopping of energy from atom to atom. This finding by Oak Ridge National Laboratory could introduce new materials as thermal energy barriers to drastically reduce energy costs, carbon emissions and waste heat.
Credit: Jill Hemman and Adam Malin/Oak Ridge National Laboratory, US Dept. of Energy
"We saw evidence for what Einstein first proposed in 1911--that heat energy hops randomly from atom to atom in thermal insulators," said Lucas Lindsay, materials theorist at ORNL. "The hopping is in addition to the normal heat flow through the collective vibration of atoms."
The random energy hopping is not noticeable in materials that conduct heat well, like copper on the bottom of saucepans during cooking, but may be detectable in solids that are less able to transmit heat.
This observation advances understanding of heat conduction in thermal insulators and will aid the discovery of novel materials for applications from thermoelectrics that recover waste heat to barrier coatings that prevent transmission of heat.
Lindsay and his colleagues used sophisticated vibration-sensing tools to detect the motion of atoms and supercomputers to simulate the journey of heat through a simple thallium-based crystal. Their analysis revealed that the atomic vibrations in the crystal lattice were too sluggish to transmit much heat.
"Our predictions were two times lower than we observed from our experiments. We were initially baffled," Lindsay said. "This led to the observation that another heat transfer mechanism must be at play."
Knowing that the second heat transfer channel of random energy hopping exists will inform researchers on how to choose materials for heat management applications. This finding, if applied, could drastically reduce energy costs, carbon emissions and waste heat.
Many useful materials, such as silicon, have a chemically bonded latticework of atoms. Heat is usually carried through this lattice by atomic vibrations, or sound waves. These heat-bearing waves bump into each other, which slows the transfer of heat.
"The thallium-based material we studied has one of the lowest thermal conductivities of any crystal," Lindsay said. "Much of the vibrating energy is confined to single atoms, and the energy then hops randomly through the crystal."
"Both the sound waves and the heat-hopping mechanism first theorized by Einstein characterize a two-channel model, and not only in this material, but in several other materials that also demonstrate ultralow conductivity," said ORNL materials scientist David Parker.
For now, heat-hopping may only be detectable in excellent thermal insulators. "However, this heat-hopping channel may well be present in other crystalline solids, creating a new lever for managing heat," he said.
The study's lead coauthor was Saikat Mukhopadhyay, a former postdoctoral research associate at ORNL and currently a National Research Council research associate at the U.S. Naval Research Laboratory.
Additional coauthors of the paper titled, "Two-channel model for ultralow thermal conductivity of crystalline Tl3VSe4," included ORNL's David S. Parker, Brian C. Sales, Alexander A. Puretzky, Michael A. McGuire and Lucas Lindsay.
This work was supported by the Department of Energy's Office of Science. Raman spectroscopy measurements were made at the Center for Nanophase Materials Sciences, and the study used computational resources from the National Energy Research Scientific Computing Center at DOE's Lawrence Berkeley National Laboratory. Both centers are DOE Office of Science User Facilities.
ORNL is managed by UT-Battelle for DOE's Office of Science. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.
Sara Shoemaker | 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
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An imaginary element X consists of two isotopes having masses of 110.00 amu and 112.00 amu. ("amu" is an atomic mass unit.) A sample of X was found to consist of 79.94% 110X and the rest is 112X. What would be the average atomic mass of X in this sample?
Give your answer to four significant figures. Do not enter any units in the box below.
A compound is composed of 52.2% carbon, 34.8% oxygen and 13.0% hydrogen, by mass. What is the empirical formula of the compound?
a. ) CHO
b. ) C2H6O1
c. ) C12H22O11
d. ) C6H11O7
e. ) CH2O3
Identify the type of reaction expected, if any, for each of the following pairs of reactants..
Assume there is enough energy input to get the reaction going, if it is favourable at room temperature (i.e. consider thermodynamics, not kinetics). If the reverse reaction is preferred, assume no reaction.
â?¢ NaHSO4(aq) + CH3NH2(aq)
â?¢ K3PO4(aq) + NiCl2(aq)
â?¢ Pb(NO3)2(aq) + Zn(ClO4)2(aq)
â?¢ P4(s) + O2(g)
â?¢ Mn(s) + NiCl2(aq) â?¢ precipitation
â?¢ acid base
â?¢ no reaction
â?¢ oxidation reduction
Select the net ionic equation for the reaction which occurs when aqueous solutions of mercurous acetate and sodium iodide are mixed :
a. Hg2(CH3COO)2 (aq) + 2 NaI (aq) --> 2 HgI (s) + 2 CH3COONa (aq)
b. Hg22+ (aq) + 2 I- (aq) --> Hg2I2 (s)
c. 2 Na+ (aq) + 2 CH3COO- (aq) --> 2 CH3COONa (aq)
d. Na+ (aq) + CH3COO- (aq) --> CH3COONa (aq)
e. Hg+ (aq) + I- (aq) --> HgI (s)
Calculate the volume (in mL) of 0.567 M HCl(aq) required to react with 46.6 mL of 0.383 M Na2CO3(aq).
Be careful to enter the correct number of significant figures. Do not enter any volume units!
From the following species (molecules and/or ions) choose the one that has the largest (most positive) oxidation number for the underlined atom.
What is the oxidizing agent in the following spontaneous reaction?
OCl-(aq) + I2(s) + 2 OH-(aq) --->Cl-(aq) + 2 OI-(aq) + H2O(l)
a. ) I2
b. ) OCl-
c. ) OI-
d. ) OH-
e. ) Cl-
Which two of the statements are FALSE regarding the balanced equation, corresponding to the following unbalanced reaction?
Co2(SO4)3(aq) + Pb(s) --> CoSO4(aq) + PbSO4(s)
a. ) Cobalt decreases its oxidation number from +3 to +2 in this reaction.
b. ) Co3+(aq) is the oxidizing agent in this reaction.
c. ) Co2+(aq) is a stronger reducing agent than Pb(s).
d. ) One mole of Co2(SO4)3(aq) consumes one mole of Pb(s).
e. ) Co3+(aq) is a weaker oxidizing agent than PbSO4(s).
When copper is heated with an excess of sulfur, Cu2S is formed. How many grams of Cu2S could be produced if 250. g of copper is heated with 100. g of sulfur?
a. 626. g
b. 125. g
c. 156.5 g
d. 313. g
e. 532. g
In the direct reaction of silicon with Cl2 the yield of SiCl4 is 40 percent. How many grams of SiCl4 are obtained in the reaction of 2.8 g of silicon with excess chlorine?
a. 170 g
b. 17 g
c. 34 g
d. 6.8 g
e. 3.4 g
Solid glucose, C6H1206(s) is burned in excess oxygen in a closed container. After the reaction, the total gas volume is 10.0 L at a temperature of 298K. What is the partial pressure, in atmospheres, of the CO2(g) produced by the complete combustion of 5.1 grams of glucose?
Be sure to enter the correct number of significant figures, but do not enter the units (atm)
This solution is provided in an attached .doc file. It answers the various chemistry review questions through explanation as well as equations. | <urn:uuid:27de0bf3-e108-4e94-9634-75a0462601df> | 3.328125 | 1,126 | Tutorial | Science & Tech. | 91.655364 | 95,500,638 |
[Global] The blue-green algae blooms that sometimes swallow Florida’s coasts are thick, green, goopy and smell like sewage. But they’re not a problem that’s unique to Florida.
The blooms gained particular notoriety in the Sunshine State during the summer of 2016, when a massive outbreak choked businesses, wildlife and tourism along both of Florida’s coasts and prompted Florida Senate President Joe Negron to champion a plan to build a massive reservoir south of Lake Okeechobee.
But communities from Toledo, Ohio to Zhoutie, China struggle with the impacts of algal blooms and the phosphorus contamination that exacerbates them.
That’s why finalists competing in a multimillion-dollar, South Florida-based competition for phosphorus removal technology are currently hard at work in Canada.
“As much as we want the technology to solve our problems here in Florida… we designed this prize to have the technology remove the phosphorus both in a cold climate and in a warm climate,” said Eric Eikenberg, CEO of the Everglades Foundation, which is one of the leaders of the $10 million George Barley Water Prize. “The challenges with excess phosphorus and freshwater are not limited to just the Everglades.”
Ten teams that hail from as near as Wellington in Palm Beach County and as far as Leeuwarden, a city in the Netherlands, are semifinalists in the multi-year contest scheduled to last through at least 2019. They come from a field of more than 200 competitors whose solutions ranged from building mechanical filtration systems to incorporating yeast byproducts from beer-brewing. They’re currently testing their technologies in Lake Simcoe, about an hour north of Toronto.
“There’s been litigation, there’s been legislation and the problem gets worse,” Eikenberg said. The solution, he said, lies “in innovation and the beauty of how humans solve problems.”
By May, the field of 10 will be whittled down to four teams competing for $10 million. Eikenberg said testing for that fourth and final stage will take place starting in 2019 in an area north of Lake Okeechobee, which has struggled with nutrient runoff from ranches and farms.
Teams “will have to have these technologies on a larger scale — billions and billions of gallons of water,” he said. Testing will happen through partnerships with agencies including the South Florida Water Management District and the St. Johns River Water Management District in Northeast Florida.
This week, another partner of the Scotts Miracle-Gro Foundation plans to release a documentary miniseries about algae’s impact on communities farther north. Andy Mann, a photographer and videographer for National Geographic, said he first saw the harm inflicted by blue-green algae when he came to South Florida to document some of the Everglades Foundation’s work. On Thursday — World Water Day — he’ll be releasing a video that shows scientists at work on solutions near Long Island Sound and a second video about the impact of algal blooms on farmers, fishermen and families near Lake Erie.
“You forget about how important a body of water is to a community,” Mann said. “When that’s taken away from people, what that does to the morale, what that does to the economy is pretty heavy.”
Mann said a third video in the series focuses on his experience documenting the blooms.
“I didn’t really think I had such a large stake in this as the videographer, but by the end, I was completely invested,” he said. “It was crazy how many people were reaching out to me, saying, ‘Oh, I grew up there,’ or ‘I’m so glad you’re shining a light on this issue.’ ”
Photo: A massive algal outbreak in Maumee Bay near Toledo, Ohio. A $10 million competition sponsored by the Everglades Foundation and the Scotts Miracle-Gro Foundation is underway to address algae outbreaks, which also plague waterways in South Florida. CHRIS ALSTRIN VIA INSTAGRAM
View original article at: How a $10 million competition takes aim at algae blooms worldwide
Contact Algae World News for algae industry advertising and other opinions: firstname.lastname@example.org | <urn:uuid:32d7e978-d129-46e5-ad90-681203c3394b> | 2.890625 | 922 | Truncated | Science & Tech. | 42.354558 | 95,500,653 |
It helps to know what you can't do first. The (2n-3) algorithm is a simple scan through the array with a max1 and max2 variable, comparing each newly encountered element against max2 and possibly max1. The worst case scenario is:
- 1 compare to add the first two elements
- 2 compares for each of the remaining n-2 elements
This gives a total of 2n-3 compares, though on randomized data you would expect an average of n+log2(n) compares. As per the problem description, worst case performance knocks linear scan out of the picture.
Similarly, we could heapify the entire array, which is guaranteed to take less than or equal to 2n compares. The first element in the resulting array is the largest, and the second largest will be either the second or third element in the array. This results in a compare count of <= 2n+1, which for randomized data and reasonably sized n will be substantially less than 2n-3. However, the worst case still makes this an unacceptable solution.
One correct answer is to use the tournament algorithm to find the 2nd largest element. In the tournament algorithm we pair up sets of two elements and then find the winner, then recursively do the same with the winners, like a knockout football game. The second largest number can be any one in the list of numbers which lost to the winner. Check the winner in the losers group (lost to the best element). This can be done in n+log(n) time complexity.
While not strictly a heap, the structure of the tournament solution is somewhat heaplike and likely what Skiena had in mind for a valid solution.
One possibility for third largest key is to heapify for <= 2n compares. The largest key will be the first array element. The second largest key will be either array element 2 or 3, requiring one compare to determine. The third largest key will be among array elements 3, 4, 5, 6, and 7 (if the second largest key was array element 2). Thus, the third largest element requires additional four compares to determine. The total compare count would be <= 2n+5.
There is also a tournament solution. The first and second largest are found in n+log(n) time as above, while the third largest can be picked as the best remaining loser to either the first or second.
While tournament has the best reliable compare count, it comes at the expense of additional storage space to store the wins and losses. The heapify option, while having a larger compare count, is in-place and in a real implementation this may make it worth using.
The trivial 'scan and compare' approach is by far the most likely approach that any real piece of software is likely to use. Its average compare count on random data is going to be similar to that of heapify, but without the complex logic and nested loops. Further, it won't have to reorder the data or keep additional storage around. It also has excellent cache locality. | <urn:uuid:2d9e18af-54dc-48e4-90f0-b90424ad31ca> | 2.5625 | 630 | Knowledge Article | Software Dev. | 56.639302 | 95,500,656 |
The Indian Space Research Organization has revealed that it will launch a lunar mission to explore that south side of the moon in October، as the Tech Times said.
The Chandrayaan-2 mission is India's second lunar mission and will mark the first time any country has visited the south side of the moon.
The mission includes a lander، an orbiter and a rectangular rover powered by solar energy. Data gathered by the rover will be sent to the lander، which will then transmit these back to ISRO for analysis.
The 6-wheeled Chandrayaan-2 rover will analyze the lunar crust to find traces of water and helium-3، an isotope crucial for the development of fusion energy on Earth.
"The mission will carry a six-wheeled Rover which will move around the landing site in semi-autonomous mode as decided by the ground commands،" ISRO said. "The instruments on the rover will observe the lunar surface and send back data، which will be useful for analysis of the lunar soil." Countries and companies worldwide are keen on exploiting helium-3 as scientists hope that the isotope can be used in a kind of nuclear fusion that does not produce radioactive waste، something that may provide safer nuclear energy. Nuclear fusion is a process that powers the sun. It involves smashing hydrogen atoms to produce helium and release massive amounts of energy. Once fusion energy is captured، it could serve as a source of unlimited energy on our planet. | <urn:uuid:a9889aa0-2268-490b-b4a4-b1e6d284db49> | 3.40625 | 305 | News Article | Science & Tech. | 42.992418 | 95,500,664 |
Ordinary cells have the ability to replace lost organs in plants—a function previously thought to be limited to stem cells—researchers at New York University's Center for Genomics and Systems Biology and Utrecht University in the Netherlands have found.
The findings, which suggest that some roles of stem cells in organ regeneration may be shared by other types of cells, are published in the latest issue of the journal Nature.
Stem cells have two known fundamental properties: they can renew themselves and they can give rise to specialized cells. These traits make them the engines for regeneration, creating new cells to replace lost organs and tissue. These phenomena are especially evident in plants, which continually re-grow their branches and roots. The center of stem cell activity is a stem cell niche, where stem cells are directed to perform these renewal and regeneration functions.
However, it's unclear how significant the stem cell niche is to organogenesis—the building and rebuilding of organs.
The scientists studied the plant Arabidopsis thaliana. The species is a good candidate for study because researchers have previously identified all of the genes expressed in its individual cells, which allows tracking of cells' identity as they regenerate.
In the study, the researchers cut off the plant's root tip, thereby excising the stem cell niche, and examined the return of cell identities by measuring all gene activity. The results suggested that stem cells returned quite late in regeneration after other cells were already replaced. The researchers then used mutant plants in which the stem cell niche no longer functions to confirm their initial observations. Despite the absence of the stem cell niche, the plant's ordinary cells worked to regenerate all the major tissues constituting the root tip—a process that began hours after it had been removed.
However, researchers found that plants without functional stem cell niches could not resume normal growth, showing that other cells did not replace all functions of stem cells.
Scientists have recently shown that manipulating non-stem cells in mammals to express several genes could convert those cells into stem cells—a process known as reprogramming. In 2008, a Nature study conducted at the Harvard Stem Cell Institute recreated pancreatic cells in mice into another type of cell that produces insulin without the aid of stem cells. In the NYU-Utrecht study, the researchers sought to determine if entire organs regenerate in plants absent of stem cells without using genetic manipulation.
"You could think of these findings as a massive reprogramming of an organ's identity without the need for a stem cell niche," said Kenneth Birnbaum, an assistant professor of biology at NYU whose lab conducted the research. "Here is a case of an organism that can perform this kind of reprogramming naturally. This may be one reason why plants are so adept at regenerating their body parts."
The work was supported by a grant from the National Institutes of Health.
James Devitt | EurekAlert!
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
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Performance on the dance floor may not always show it, but people are rarely born with two left feet. We have genes that instruct our arms and legs to grow in the right places and point in the right directions. They also provide for the spaces between our fingers and toes and every other formative detail of our limbs.
Evolutionarily speaking, the genetic instructions used to construct and position our limbs were being perfected more than half a billion years ago in fishes, not along the sides of the body where the fins that preceded human arms and legs sprouted, but at the midline that runs along the backbone and belly.
This midline -- think of the dorsal, tail and anal fins of a fish - is where the genetic template to produce fins originated, about 100 million years before paired fins evolved and about 200 million years before paired fins evolved into limbs, according to University of Florida genetics researchers. The findings, published online today in the journal Nature, also provide insight into the evolutionary history of genes involved in human birth defects.
"Given that paired fins made their evolutionary debut at a particular location on the sides of the body, intuitively one would think the genetic tools for fin development would be brought together in that place," said developmental biologist Martin Cohn, Ph.D., an associate professor with the UF departments of zoology and anatomy and cell biology and a member of the UF Genetics Institute. "We've discovered that the genetic circuitry for building limbs first appeared in an entirely different place - the midline of the animal."
The appearance of paired fins on the sides of early vertebrates was a major evolutionary innovation toward fin - and eventually limb - locomotion, Cohn said. The earliest fishes lacked paired fins, similar to the modern-day lamprey - a species of jawless fish with a dorsal fin and tail but no side fins - considered by biologists to share many features with the ancestor of all vertebrates.
"The emergence of paired appendages was a critical event in the evolution of vertebrates," Cohn said. "The fossil record provides clear evidence that the first fins evolved along the midline. The sequence of evolutionary events leading to the origin of limbs has been known for some time, but only now are we deciphering how these events occurred at a molecular genetic level."
Researchers isolated genes from the spotted catshark, a type of slow-moving shark from the eastern Atlantic Ocean. By studying the activity of a dozen genes in shark embryos, they determined shark median fin development is associated with the presence of genes such as HoxD, Fgf8 and Tbx18, which are vital in the development of human limbs.
They also used molecular markers for different cell types to determine which cells give rise to the median fins, finding that they arise from the same cells that form the vertebrae. These same genes dictate the emergence of symmetrical pairs of fins on the animal sides, showing a shared developmental mechanism in completely different locations, according to Renata Freitas and GuangJun Zhang, co-authors of the paper and graduate students in UF's zoology department.
Extending their genetic analysis to the lamprey - a living relic from the time before fish had paired fins - researchers found the same genetic cues in place.
"That we see these same mechanisms operating in lamprey fins tells us they must have been assembled in the median fins first, and later in evolution this entire genetic program was simply reutilized in a new position to build the first paired fins," Cohn said. "It tells us our own arms and legs have their evolutionary roots in the dorsal, caudal and anal fins of our fishy ancestors."
Many of these genetic mechanisms are involved in human birth defects, which provide insight into the evolutionary history of genes and their functions.
"Knowing that many of these genes are responsible for limb defects in humans is intriguing," Cohn said. "What we've done is identify where those developmental pathways originated during our evolutionary past and how they became involved in limb development."
Learning the mechanics of development enriches our understanding of evolution, according to Ann Campbell Burke, Ph.D., an associate professor of biology at Wesleyan University who was not connected with the study.
"Using modern molecular techniques, this confirms in a lovely way an idea that's been around for over 100 years about how paired fins may have evolved in the first place," Burke said. "To translate a 19th century observation about fin development into modern molecular data is a great thing for science. It has become increasingly important to understand developmental processes in our attempts to understand evolution."
John D. Pastor | EurekAlert!
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
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First ever gravitationally lensed Type Ia supernovae discovered
Two teams of astronomers using the NASA/ESA Hubble Space Telescope have discovered three distant exploding stars that have been magnified by the immense gravity of foreground galaxy clusters, which act like "cosmic lenses". These supernovae offer astronomers a powerful tool to check the prescription of these massive lenses.
Massive clusters of galaxies act as “gravitational lenses” because their powerful gravity bends light passing through them . This lensing phenomenon makes faraway objects behind the clusters appear bigger and brighter — objects that might otherwise be too faint to see, even with the largest telescopes.
The new findings are the first steps towards the most precise prescription — or map — ever made for such a lens. How much a gravitationally lensed object is magnified depends on the amount of matter in a cluster — including dark matter, which we cannot see directly . Astronomers develop maps that estimate the location and amount of dark matter lurking in a cluster. These maps are the lens prescriptions of a galaxy cluster and predict how distant objects behind a cluster will be magnified when their light passes through it. But how do astronomers know this prescription is accurate?
Now, two independent teams of astronomers from the Supernova Cosmology Project and the Cluster Lensing And Supernova survey with Hubble (CLASH) have found a new method to check the prescription of a gravitational lens. They analysed three supernovae — nicknamed Tiberius, Didius and Caracalla — which were each lensed by a different massive galaxy cluster — Abell 383, RXJ1532.9+3021 and MACS J1720.2+3536, respectively. Luckily, two and possibly all three of these supernovae appeared to be a special type of exploding star that can be used as a standard candle .
“Here we have found Type Ia supernovae that can be used like an eye chart for each lensing cluster,” explained Saurabh Jha of Rutgers University, USA, a member of the CLASH team. “Because we can estimate the intrinsic brightness of the Type Ia supernovae, we can independently measure the magnification of the lens, which is not possible with other background sources."
The teams measured the brightnesses of the lensed supernovae and compared them to the explosion's intrinsic brightness to calculate how much brighter the exploding stars' were made due to gravitational lensing. One supernova in particular stood out, appearing to be about twice as bright as would have been expected if not for the cluster's magnification power.
The three supernovae were discovered in the CLASH survey, which used Hubble to probe the distribution of dark matter in 25 galaxy clusters. Two of the supernovae were found in 2012; the other in 2010 to 2011.
To perform their analyses, both teams used Hubble observations alongside observations from both space and ground-based telescopes to provide independent estimates of the distances to these exploding stars .
In some cases the observations allowed direct confirmation of a Type Ia pedigree. In other cases the supernova spectrum was weak or overwhelmed by the light of its parent galaxy. In those cases the brightening and fading behaviour of the supernovae in different colours was used to help establish the supernova type.
Each team compared its results with independent theoretical models of the clusters' dark matter content. They each came to the same conclusions: that the predictions fit the models.
“It is encouraging that the two independent studies reach quite similar conclusions,” explained Supernova Cosmology Project team member Jakob Nordin of the E.O. Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California, Berkeley. “These pilot studies provide very good guidelines for making future observations of lensed supernovae even more accurate.” Nordin is the lead author on the team's science paper describing the findings.
The Supernova Cosmology Project's galaxy cluster models were created by team members Johan Richard of the University of Lyon in France, and Jean-Paul Kneib of Ecole Polytechnique Federale de Lausanne in Switzerland. “It’s really great to see that these supernovae are behaving in the way we expected,” says Kneib. “The more confirmation we get that our complex cluster models are correct, the more we can rely on them, and use them to probe the early Universe.”
“Building on our understanding of these lensing models also has implications for a wide range of key cosmological studies,” added Supernova Cosmology Project leader Saul Perlmutter of Berkeley Lab and the University of California, Berkeley. “These lens prescriptions yield measurements of the cluster masses, allowing us to probe the cosmic competition between gravity and dark energy as matter in the Universe gets pulled into galaxy clusters.” Dark energy being a mysterious and invisible energy that is accelerating the Universe's expansion.
The astronomers are optimistic that Hubble surveys such as Frontier Fields and future telescopes, including the infrared James Webb Space Telescope, will find more of these unique exploding stars. This is important as if you want to check the prescription of your lens, you really want to check it in more than one place. “Hubble is already hunting for them in the Frontier Fields, a three-year Hubble survey of the distant universe which uses massive galaxy clusters as gravitational lenses, to reveal what lies beyond them” said CLASH team member Brandon Patel of Rutgers University, the lead author on the science paper announcing the CLASH team's results.
The results from the CLASH team will appear in the May 2014 issue of The Astrophysical Journal. The Supernova Cosmology Project's findings will appear in the May 2014 edition of the Monthly Notices of the Royal Astronomical Society.
Albert Einstein predicted this effect in his theory of general relativity.
Dark matter is believed to make up the bulk of the Universe's matter, and is therefore the source of most of a cluster's gravity.
An astronomical "standard candle" is any type of luminous object whose intrinsic power is so accurately determined that it can be used to make distance measurements based on the rate the light dims over astronomical distances.
The astronomers obtained observations in visible light from Hubble's Advanced Camera for Surveys and in infrared light from the Wide Field Camera 3.
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
The work is published in two papers, the CLASH team in The Astrophysical Journal and the Supernova Cosmology Project's findings in Monthly Notices of the Royal Astronomical Society.
The CLASH survey is led by Marc Postman of the Space Telescope Science Institute. The CLASH supernova project is co-led by Adam Riess of the Space Telescope Science Institute and Johns Hopkins University and Steven Rodney of Johns Hopkins University. Aiding with the analysis on this Hubble study are Curtis McCully of Rutgers University and Julian Merten and Adi Zitrin of the California Institute of Technology in Pasadena. Lead author of the paper was Brandon Patel.
The Supernova Cosmology Project included Jakob Nordin and Saul Perlmutter and others who worked on the supernovae analysis are David Rubin of Florida State University in Tallahassee and Greg Aldering of Lawrence Berkeley National Lab.
Image credit: NASA, ESA, S. Perlmutter (UC Berkeley, LBNL), A. Koekemoer (STScI), M. Postman (STScI), A. Riess (STScI/JHU), J. Nordin (LBNL, UC Berkeley), D. Rubin (Florida State), and C. McCully (Rutgers University)
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Biological molecules make up all living creatures on earth and contain four major elements -- hydrogen, carbon, nitrogen and oxygen. But until now scientists were only able to use nuclear magnetic resonance (NMR) to study three out of the four elements in the molecule puzzle because oxygen wavelengths were difficult to detect.
"Oxygen signals were so weak, so to speak, that no one could make use of them," says chemistry professor Gang Wu. "Now there is a way of detecting them even in complex biomolecular systems."
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Species exchange between North and South America created one of the most biologically diverse regions on Earth.
A new study by Smithsonian scientists and colleagues published this week in the Proceedings of the National Academy of Sciences shows that species migrations across the Isthmus of Panama began about 20 million years ago, some six times earlier than commonly assumed. These biological results corroborate advances in geology, rejecting the long-held assumption that the Isthmus is only about 3 million years old.
"Even organisms that need very specific conditions to survive, such as salamanders and freshwater fishes, crossed the Isthmus of Panama over 6 million years ago," said lead author, Christine Bacon, former post-doctoral fellow in staff scientist Carlos Jaramillo's group at the Smithsonian Tropical Research Institute. "These early migrations impact our understanding of how and when biodiversity in the Americas took shape."
The Isthmus of Panama, which links North and South America, plays a crucial role in the planet's atmospheric and oceanic circulation, climate and biodiversity. Despite its importance across multiple disciplines, the timing of the formation and emergence of the Isthmus and the effect it had on those continents' biodiversity is controversial.
In the new study, Bacon, now at the University of Gothenburg in Sweden, examines a large number of molecular studies and fossils, including land and aquatic organisms.
Models based on molecular genetic data indicate that rather than one great migration following a set closure time, there were several periods in which animals and plants moved across the intercontinental land bridge. There are shifts in the rate of movement of animal fossils moving from North America to South America at 23 million and within the past 10 million years.
Authors also compare the proportion of immigrants in each direction to sea level and global mean temperature, showing that migrations may have coincided with low sea levels.
A known date for the rise of the Isthmus is important to evolutionary biologists who want to understand how species of marine organisms diverged and when species of terrestrial organisms moved from one continent to another. The date is also critical in understanding ancient climate change patterns.
The 3 million year date was established by the Panama Paleontology Project, headed by Jeremy Jackson and Anthony Coates, also at the Smithsonian Tropical Research Institute.
The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is a part of the Smithsonian Institution. The institute furthers the understanding of tropical nature and its importance to human welfare, trains students to conduct research in the tropics and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems.
Bacon, C.D., D. Silvestro, C.A. Jaramillo, B. Tilston Smith, P. Chakrabarty, A. Antonelli. Biological evidence shows earlier emergence of the Isthmus of Panama. Accepted, Proceedings of the National Academy of Sciences USA. doi:10.1073/pnas.1423853112
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- Research highlight
- Open Access
The pea aphid genome sequence brings theories of insect defense into question
© BioMed Central Ltd 2010
Published: 23 February 2010
The genome sequence of the pea aphid is the first for a basal hemimetabolous insect and provides insights into developmental plasticity, symbiosis and insect immunity.
The pea aphid life cycle
The ecology, physiology and evolution of the hemipteran insect pea aphid (Acyrthosiphon pisum) has been well studied because of its fascinating phenotypic plasticity, its heritable symbiotic associations and its impact on agriculture. Aphids are soft-bodied sap-feeding insects that act as vectors for plant viruses and cause worldwide crop damage. Sequencing and analysis of the pea aphid genome by the International Aphid Genomics Consortium (IAGC) has provided new insights into aphid development and their interactions and coevolution with obligate and facultative symbiotic bacteria. Among the studies enabled by the genome project is the characterization of genes involved in the pea aphid immune and defense systems, published in this issue of Genome Biology .
The genome of the pea aphid is the first to be sequenced of the hemimetabolous group of insects, characterized by life cycles with incomplete metamorphosis from juvenile to adult stages. The annual aphid life cycle is particularly interesting because it includes a single sexual generation that alternates with several consecutive all-female parthenogenic generations (reviewed in ). The sexual males and females mate in the autumn, producing diapausing eggs that overwinter and hatch in the spring to produce the first all-female generation. The reduction division of meiosis I does not occur in the asexual females, allowing parthenogenesis. The embryos develop within their asexual mothers and can even contain embryos themselves. Several rapidly developing generations of asexual females are produced until autumn, when the shortened photoperiod induces the last asexual generation to give rise to sexual females and sexual males, completing the cycle. Sex determination in pea aphid is XX/XO, with males being XO. The males are produced by removal of one X chromosome during meiosis II. Given that all sperm carry an X chromosome, the following sexually produced generation is all female .
Rapid reproduction during the asexual phase of the life cycle allows aphids to adapt quickly to new environments and host plants, and it has contributed to the development of alternative phenotypes (polyphenisms) among individuals with identical genotypes. These polyphenisms, such as asexual versus sexual females, winged versus wingless asexual females and morphs specialized to resist extreme environments or defend the colony, make the pea aphid a good system for investigating the effect of environmental cues on development . Indeed, Miura et al. found that the development of asexual and sexual embryos was highly divergent, despite being controlled by identical genomes in clonally produced individuals. The pea aphid genome sequence shows remarkably extensive gene duplication, with more than 2,000 gene families that are expanded compared with the published genomes of other insects, suggesting that the unusual developmental patterns may be facilitated by duplications of genes related to development and cell cycle . For example, lineage-specific duplications in several mitotic regulators and mitosis-related genes may contribute to plasticity of the cell cycle .
In addition to providing a model for phenotypic plasticity, the pea aphid is the best-studied model for maternally transmitted symbionts (reviewed in [4, 5]). Pea aphids have coevolved with the obligate intracellular symbiont Buchnera aphidicola for over 100 million years. Buchnera are Gram-negative bacteria that exist only within specialized cells of pea aphids called bacteriocytes and are transferred vertically from mother to embryos. In addition to the obligate symbiont, pea aphids have more recent associations with vertically transmitted facultative symbionts, including the Gram-negative bacteria Regiella insecticola, Serratia symbiotica and Hamiltonella defensa (reviewed in ). Although they are not required for host vitality, they confer benefits such as protection against parasitoid wasps, fungal pathogens and heat .
Nutritional, physiological and functional studies (reviewed in [5, 7]), in addition to a completely sequenced genome of the Buchnera strain that infects the pea aphid , have provided clues about the nature of the interdependency between host and symbiont. Annotation of the Buchnera genome supports previous studies indicating that although Buchnera has a dramatically reduced gene repertoire, it provides amino acids that the host cannot produce. The Buchnera genome includes genes involved in biosysnthesis of the nine amino acids that are known to be essential to animals (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine), but very few genes involved in synthesis of non-essential amino acids . Manual annotation of the pea aphid genome indeed shows that it lacks machinery to synthesize the nine amino acids that are essential to other animals . In addition, pea aphid cannot synthesize arginine due to the complete lack of urea cycle genes . Previous studies (for example, ) have suggested that the host provides what the symbiont cannot produce. The IAGC confirmed the coordination of metabolism between host and symbiont. For example, rather than excreting nitrogenous waste, pea aphid recycles amino groups as glutamine, which Buchnera then incorporates into the production of arginine [1, 8]. Remarkably, annotation of the pea aphid genome suggests that several additional amino acid and purine metabolism pathways include steps encoded across the two genomes (see Figure 9 in ).
The availability of host and symbiont genomes facilitates the investigation of lateral gene transfer. The previously sequenced genomes of Buchnera (for example, ) have shown no evidence of gene uptake from the host . Now, the IAGC has been able to perform the first exhaustive search for lateral gene transfer in the genome of a eukaryotic host that has heritable associations with symbiotic bacteria. They found 12 genes or gene fragments of bacterial origin . Although some of these genes had been found previously to be highly expressed in bacteriocytes so may function in the regulation of the symbiosis , overall there was little transfer of bacterial genes to the host genome .
Immunity and defense
Adding to the complexity of the pea aphid system are associations with enemies such as pathogenic fungi and parasitic wasps, which leads to the question of how aphid defense mechanisms operate. Gerardo et al. begin to address that question by manually annotating the pea aphid genome to determine the presence or absence of immune- and stress-related genes found in other insects, such as Drosophila, then performing RNA and protein expression analyses of pathogen-challenged and uninfected aphids. They systematically sought genes related to microbial recognition, signaling pathways and response. Their results show that pea aphids are missing many immune- and stress-related genes found in all other insects with published genomes, and that their RNA and protein expression responses to infection are limited .
The most striking differences in microbial recognition genes between pea aphid and other studied insects are the lack of peptidoglycan receptor proteins (PGRPs), class C scavenger receptors and epidermal growth factor (EGF)-repeat-containing genes in pea aphids . Drosophila PGRPs recognize peptidoglycans in the cell walls of Gram-negative and Gram-positive bacteria, and this leads to the activation of the Toll and immunodeficiency/c-Jun N-terminal kinase (JNK) pathways. The recognition of Gram-positive bacteria in Drosophila is preceded by the formation of a complex between Gram-negative binding proteins (GNBPs) and PGRPs and hydrolysis of peptidoglycans into small fragments by GNBPs. The authors found it surprising that pea aphids have two GNBP paralogs, despite lacking PGRPs, and suggested that GNBPs may have a different role in pea aphids . Pea aphids have no class C scavenger receptors , which facilitate phagocytosis in Drosophila. The pea aphid genome also lacks EGF repeats, which are found in members of the Nimrod superfamily, thought to serve as receptors in phagocytosis and bacterial binding in other insects .
As for signaling pathways, Gerardo et al. found the Toll and Janus kinase/signal transducer (JAK/STAT) pathways to be intact. These are both thought to be involved in development and innate immunity. On the other hand, they could not identify many components of the immunodeficiency (IMD) signaling pathway, which is critical for fighting Gram-negative bacteria in Drosophila and may also have a role in defense against Gram-positive bacteria and fungi (see Figure 1 in ). The IMD pathway genes missing in pea aphid have conserved one-to-one orthologs in most other published insect genome sequences . Since the IMD pathway triggers the JNK pathway in Drosophila, the authors found it surprising that the pea aphid genome does include most components of the JNK pathway .
Pea aphids differ extensively in their defense response genes compared with those known in other insects . They are missing many of the antimicrobial peptides (AMPs) that are conserved in other insects (see for a complete list). Notably, pea aphids lack defensins, which have been found in all insect genomes sequenced so far. Similar to the red flour beetle (Tribolium castaneum) but unlike any other sequenced insect genome, the pea aphid genome contains plant-like thaumatin homologs, which have anti-fungal properties in plants. The authors suggest that these are ancient defense genes that have been lost in many insect species. Another striking finding is that pea aphid lacks C-type lysozymes, which are the most common class of lysozyme in metazoa and which have been found in all other sequenced insect genomes . Lysozymes are a family of enzymes that degrade bacterial cell walls. Pea aphids do have three i-type (invertebrate) lysozymes . In addition, two genes that were found to be of bacterial origin encode bacteriolytic enzymes similar to lysozymes .
Gerardo et al. then went on to investigate expression of 23 of the recognition, signaling and response genes in aphids that had been subjected to infection and stress treatments and, remarkably, found no upregulation of AMPs in infected aphids. Similarly, in expressed sequence tag (EST)-based experiments comparing cDNA libraries synthesized from guts of infected and uninfected aphids, they did not detect any standard immune related genes. They then used suppression subtractive hybridization (SSH) to compare cDNA from infected and uninfected aphids. Briefly, SSH is a technique in which PCR amplification of cDNAs that are common between two samples is selectively suppressed, so that only differentially expressed cDNAs are amplified and subsequently cloned and sequenced. Optimizing the control and experimental sample ratio ensures that cDNAs more abundantly expressed in the experimental sample (in this case infected aphids) are selectively amplified. The infected versus uninfected aphid SSH library included few immune-related genes, and again, no AMPs. Finally, high performance liquid chromatography (HPLC) peptide analyses targeting small peptides, such as AMPs, were run on the hemolymph of infected aphids and also suggested a lack of AMP response .
The findings of Gerardo et al. suggest that pea aphids, and possibly other hemimetabolous insects, have a defense system that differs greatly from other well-studied insects, most of which are holometabolous, bringing the authors to question the generality of the accepted insect model of immunity. Their functional analyses agree with a previous SSH study investigating wound-mediated expression in aphid, which also found no AMPs to be present in hemolymph . Gerardo et al. revisit hypotheses proposed by Altincicek et al. to explain the seemingly deficient antimicrobial defenses in pea aphid and suggest that both increased reproduction following infection and symbiont-mediated host protection may contribute to the aphid's defenses.
In summary, I have highlighted a few of the outcomes of the pea aphid genome analysis, which revealed new perspectives on questions related to aphid phenotypic plasticity, symbiosis and defense mechanisms. As the first genome of a hemimetabolous insect, it will reveal the diversity of biological mechanisms among insects and expand our traditional models of fundamental processes, such as immunity and stress response. Combined with the sequences of several symbiont genomes, the pea aphid genome will advance the study of coevolution and encourage a multi-organismal systems biology approach.
- The International Aphid Genomics Consortium: Genome sequence of the pea aphid Acrythosiphon pisum. PLoS Biol. 2010, 8: e1000313-10.1371/journal.pbio.1000313.PubMed CentralView ArticleGoogle Scholar
- Gerardo NM, Altincicek B, Anselme C, Atamian H, Barribeau SM, de Vos M, Duncan E, Evans JD, Gabaldon T, Ghanim M, Heddi A, Kaloshian I, Latorre A, Moya A, Nakabachi A, Parker BJ, Perez-Brocal V, Pignatelli M, Rhabe Y, Ramsey JS, Spragg C, Tamames J, Tamarit D, Tamborindeguy C, Vincent-Monegat C, Vilcinskas A: Immunity and other defenses in pea aphids, Acyrthosiphon pisum. Genome Biol. 2010, 11: R21-PubMedPubMed CentralView ArticleGoogle Scholar
- Miura T, Braendle C, Shingleton A, Sisk G, Kambhampati S, Stern DL: A comparison of parthenogenetic and sexual embryogenesis of the pea aphid Acyrthosiphon pisum (Hemiptera: Aphidoidea). J Exp Zool B Mol Dev Evol. 2003, 295: 59-81.PubMedView ArticleGoogle Scholar
- Moran NA, McCutcheon JP, Nakabachi A: Genomics and evolution of heritable bacterial symbionts. Annu Rev Genet. 2008, 42: 165-190. 10.1146/annurev.genet.41.110306.130119.PubMedView ArticleGoogle Scholar
- Moran NA, Degnan PH: Functional genomics of Buchnera and the ecology of aphid hosts. Mol Ecol. 2006, 15: 1251-1261. 10.1111/j.1365-294X.2005.02744.x.PubMedView ArticleGoogle Scholar
- Oliver KM, Russell JA, Moran NA, Hunter MS: Facultative bacterial symbionts in aphids confer resistance to parasitic wasps. Proc Natl Acad Sci USA. 2003, 100: 1803-1807. 10.1073/pnas.0335320100.PubMedPubMed CentralView ArticleGoogle Scholar
- Douglas AE: Nutritional interactions in insect-microbial symbioses: aphids and their symbiotic bacteria Buchnera. Annu Rev Entomol. 1998, 43: 17-37. 10.1146/annurev.ento.43.1.17.PubMedView ArticleGoogle Scholar
- Shigenobu S, Watanabe H, Hattori M, Sakaki Y, Ishikawa H: Genome sequence of the endocellular bacterial symbiont of aphids Buchnera sp. APS. Nature. 2000, 407: 81-86. 10.1038/35024074.PubMedView ArticleGoogle Scholar
- Nikoh N, Nakabachi A: Aphids acquired symbiotic genes via lateral gene transfer. BMC Biol. 2009, 7: 12-10.1186/1741-7007-7-12.PubMedPubMed CentralView ArticleGoogle Scholar
- Altincicek B, Gross J, Vilcinskas A: Wounding-mediated gene expression and accelerated viviparous reproduction of the pea aphid Acyrthosiphon pisum. Insect Mol Biol. 2008, 17: 711-716. 10.1111/j.1365-2583.2008.00835.x.PubMedView ArticleGoogle Scholar | <urn:uuid:d6c3f63b-438f-4c92-b317-6c2e86fed2f6> | 3.375 | 3,564 | Academic Writing | Science & Tech. | 26.618253 | 95,500,718 |
How does the relationship between science and technology affect environmental problems AND solutions in today's society?© BrainMass Inc. brainmass.com July 23, 2018, 12:21 am ad1c9bdddf
The relationship between science and technology
How does the relationship between science and technology affect environmental problems AND solutions in today's society?
Since the rise of the Industrial Revolution in the latter part of the 18th century, science and technology have shifted our progress in energy, physical materials, research, information and communications, medicine, and many other sectors. Such major enhancements have resulted in vast improvements in our health, economic prosperity, and everyday living. Furthermore, progress in energy and materials technologies has given rise to a variety of new transportation modes, including the airplane, railroad, the automobile, and in so many other areas. Science is great and so is technology. However, creating science and technology often causes environmental clashes and problems, such as pollution that is emitted from a non-hybrid car. Those who care about the environment and environmentalists by utilizing the power of science can try to remedy the situation by concocting experiments and solutions with science. These could include but are not limited to: solar panels; hybridized cars (e.g., the Prius); catalytic converters) and so on. The complementary two have greatly impacted our society and have improved human mobility in terms of both time and space. Advances in cell mobility coupled with the recent and major inventions in the area of telecommunications technology, such as the telephone, television, and radio, have served to broaden the range of what we can do, where we can go, and how we can get there and how we will do those things.
Science and ...
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Inductively coupled plasma
An inductively coupled plasma (ICP) or transformer coupled plasma (TCP) is a type of plasma source in which the energy is supplied by electric currents which are produced by electromagnetic induction, that is, by time-varying magnetic fields.
In planar geometry, the electrode is a length of flat metal wound like a spiral (or coil). In cylindrical geometry, it is like a helical spring. In half-toroidal geometry, it is toroidal solenoid cut along its main diameter to two equal halves.
When a time-varying electric current is passed through the coil, it creates a time-varying magnetic field around it, with flux
where r is the distance to the center of coil (and of the quartz tube).
which corresponds to electric field strengths of
leading to the formation of the figure-8 electron trajectories providing a plasma generation. The dependence on r suggests that the gas ion motion is most intense in the outer region of the flame, where the temperature is the greatest. In the real torch, the flame is cooled from the outside by the cooling gas, so the hottest outer part is at thermal equilibrium. There temperature reaches 5 000–6 000 K. For more rigorous description, see Hamilton-Jacobi equation in electromagnetic fields.
The frequency of alternating current used in the RLC circuit which contains the coil usually 27–41 MHz. To induce plasma, a spark is produced at the electrodes at the gas outlet. Argon is one example of a commonly used rarefied gas. The high temperature of the plasma allows the determination of many elements, and in addition, for about 60 elements degree of ionization in the torch exceeds 90 %. The ICP torch consumes ca. 1250–1550 W of power, but this depends on the elemental composition of the sample (due to different ionization energies).
Plasma electron temperatures can range between ~6 000 K and ~10 000 K (~6 eV - ~100 eV), comparable to the surface of the sun. ICP discharges are of relatively high electron density, on the order of 1015 cm−3. As a result, ICP discharges have wide applications where a high-density plasma (HDP) is needed.
- ICP-AES, a type of atomic emission spectroscopy.
- ICP-MS, a type of mass spectrometry.
- ICP-RIE, a type of reactive-ion etching.
- Exciting a beam of noble gas to the metastable state.
Another benefit of ICP discharges is that they are relatively free of contamination, because the electrodes are completely outside the reaction chamber. By contrast, in a capacitively coupled plasma (CCP), the electrodes are often placed inside the reactor and are thus exposed to the plasma and subsequent reactive chemical species.
- Pulsed inductive thruster
- Induction plasma technology
- List of plasma (physics) articles
- Capacitively coupled plasma
- High density fluorocarbon etching of silicon in an inductively coupled plasma: Mechanism of etching through a thick steady state fluorocarbon layer T. E. F. M. Standaert, M. Schaepkens, N. R. Rueger, P. G. M. Sebel, and G. S. Oehrleinc
- A. Montaser and D. W. Golightly, eds. (1992). Inductively Coupled Plasmas in Analytical Atomic Spectrometry. VCH Publishers, Inc., New York,.
- Lajunen, L. H. J.; Perämäki, P. (2004). Spectrochemical Analysis by Atomic Absorption and Emission (2 ed.). Cambridge: RSC Publishing. p. 205. ISBN 0-85404-624-0.
- Pascal Chambert and Nicholas Braithwaite (2011). "Physics of Radio-Frequency Plasmas". Cambridge University Press, Cambridge: 219–259. ISBN 978-0521-76300-4.
- Shun'ko, Evgeny V.; Stevenson, David E.; Belkin, Veniamin S. (2014). "Inductively Coupling Plasma Reactor With Plasma Electron Energy Controllable in the Range From ~6 to ~100 eV". IEEE Transactions on Plasma Science. 42 (3): 774–785. Bibcode:2014ITPS...42..774S. doi:10.1109/TPS.2014.2299954. ISSN 0093-3813.
- Бабушкин, А. А.; Бажулин, П. А.; Королёв, Ф. А.; Левшин, Л. В.; Прокофьев, В. К.; Стриганов, А. Р. (1962). "Эмиссионный спектральный анализ". In Гольденберг, Г. С. Методы спектрального анализа. Москва: Издательство МГУ. p. 58.
- Dunnivant, F. M.; Ginsbach, J. W. (2017). Flame Atomic Absorbance and Emission Spectrometry and Inductively Coupled Plasma — Mass Spectrometry. Whitman College. Retrieved 10 January 2018.
- Ben Ohayon, Erik Wahlin and Guy Ron (2015). "Characterization of a metastable neon beam extracted from a commercial RF ion source". 10 (03). Journal of Instrumentation, Cambridge: P03009. arXiv: . Bibcode:2015JInst..10P3009O. doi:10.1088/1748-0221/10/03/P03009. | <urn:uuid:1312023d-f844-4eaa-accb-1c13ae2dbbfc> | 3.5 | 1,336 | Knowledge Article | Science & Tech. | 68.416166 | 95,500,768 |
For a few millionths of a second after the Big Bang, the universe consisted of a hot soup of elementary particles called quarks and gluons. A few microseconds later, those particles began cooling to form protons and neutrons, the building blocks of matter.
Over the past decade, physicists around the world have been trying to re-create that soup, known as quark-gluon plasma (QGP), by slamming together nuclei of atoms with enough energy to produce trillion-degree temperatures.
“If you’re interested in the properties of the microseconds-old universe, the best way to study it is not by building a telescope, it’s by building an accelerator,” says Krishna Rajagopal, an MIT theoretical physicist who studies QGP.
Quarks and gluons, though they make up protons and neutrons, behave very differently from those heavier particles. Their interactions are governed by a theory known as quantum chromodynamics, developed in part by MIT professors Jerome Friedman and Frank Wilczek, who both won Nobel prizes for their work. However, the actual behavior of quarks and gluons is difficult to study because they are confined within heavier particles. The only place in the universe where QGP exists is inside high-speed accelerators, for the briefest flashes of time.
In 2005, scientists at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory reported creating QGP by smashing gold atoms together at nearly the speed of light. These collisions can produce temperatures up to 4 trillion degrees — 250,000 times warmer than the sun’s interior and hot enough to melt protons and neutrons into quarks and gluons.
The resulting super-hot, super-dense blob of matter, about a trillionth of a centimeter across, could give scientists new insights into the properties of the very early universe. So far, they have already made the surprising discovery that QGP is a nearly frictionless liquid, not the gas that physicists had expected.
By doing higher-energy collisions, scientists now hope to find out more about the properties of quark gluon plasma and whether it becomes gas-like at higher temperatures. They also want to delve further into the very surprising similarities that have been seen between QGP and ultracold gases (near absolute zero) that MIT’s Martin Zwierlein and others have created in the laboratory. Both substances are nearly frictionless, and theoretical physicists suspect that string theory may explain both phenomena, says Rajagopal.
At the Large Hadron Collider in Geneva, MIT faculty Gunther Roland, Wit Busza and Boleslaw Wyslouch are among the physicists planning to double the temperature achieved at Brookhaven, offering a glimpse of an even-earlier stage of the universe’s formation.
Explore further: 'Perfect' Liquid Hot Enough to be Quark Soup (w/ Video)
Other "Explained" stories can be found: www.physorg.com/search/sort/da … Explained&headline=1 | <urn:uuid:436da323-2dad-4db9-885e-cd51cba4f140> | 3.71875 | 635 | News Article | Science & Tech. | 33.349866 | 95,500,773 |
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A black and white rendition of the Yale Babylonian Collection's Tablet YBC 7289 (c. 1800-1600 BCE), showing a Babylonian approximation to the square root of 2 (1 24 51 10 w: sexagesimal) in the context of Pythagoras' Theorem for an isosceles triangle. The tablet also gives an example where one side of the square is 30, and the resulting diagonal is 42 25 35 or 42.4263888.
Computational mathematics may refer to two different aspect of the relation between computing and mathematics. Computational applied mathematics consists roughly of using mathematics for allowing and improving computer computation in applied mathematics. Computational mathematics may also refer to the use of computers for mathematics itself. This includes the use of computers for mathematical computations (computer algebra), the study of what can (and what cannot) be computerized (and what cannot) in mathematics (effective methods), which computations may be done with present technology (complexity theory), and which proofs can be done on computers (proof assistants).
Computational applied mathematics involves mathematical research in areas of science where computing plays a central and essential role, emphasizing algorithms, numerical methods, and symbolic computations. Computation in research is prominent. Computational mathematics emerged as a distinct part of applied mathematics by the early 1950s. Currently, computational mathematics can refer to or include:
- computational science, also known as scientific computation or computational engineering
- solving mathematical problems by computer simulation as opposed to analytic methods of applied mathematics
- numerical methods used in scientific computation, for example numerical linear algebra and numerical solution of partial differential equations
- stochastic methods, such as Monte Carlo methods and other representations of uncertainty in scientific computation, for example stochastic finite elements
- the mathematics of scientific computation (the theoretical side involving mathematical proofs), in particular numerical analysis, the theory of numerical methods (but theory of computation and complexity of algorithms belong to theoretical computer science)
- symbolic computation and computer algebra systems
- computer-assisted research in various areas of mathematics, such as logic (automated theorem proving), discrete mathematics (search for mathematical structures such as groups), number theory (primality testing and factorization), cryptography, and computational algebraic topology
- computational linguistics, the use of mathematical and computer techniques in natural languages
- computational algebraic geometry
- computational group theory
- computational geometry
- computational number theory
- computational topology
- computational statistics
- algorithmic information theory
- algorithmic game theory
- use of mathematics in economics, finance and to certain extents of accounting i.e. use of differential and integral calculus(newton's method) and financial maths to solve real life problems.
- Cucker, F. (2003). Foundations of Computational Mathematics: Special Volume. Handbook of Numerical Analysis. North-Holland Publishing. ISBN 978-0-444-51247-5.
- Harris, J. W.; Stocker, H. (1998). Handbook of Mathematics and Computational Science. Springer-Verlag. ISBN 978-0-387-94746-4.
- Hartmann, A.K. (2009). Practical Guide to Computer Simulations. World Scientific. ISBN 978-981-283-415-7.
- Nonweiler, T. R. (1986). Computational Mathematics: An Introduction to Numerical Approximation. John Wiley and Sons. ISBN 978-0-470-20260-9.
- Gentle, J. E. (2007). Foundations of Computational Science. Springer-Verlag. ISBN 978-0-387-00450-1.
- White, R. E. (2003). Computational Mathematics: Models, Methods, and Analysis with MATLAB. Chapman and Hall. ISBN 978-1584883647.
- Yang, X. S. (2008). Introduction to Computational Mathematics. World Scientific. ISBN 978-9812818171.
- Strang, G. (2007). Computational Science and Engineering. Wiley. ISBN 978-0961408817. | <urn:uuid:625680bf-788a-454c-bb29-ce179fbac156> | 2.953125 | 894 | Knowledge Article | Science & Tech. | 25.321939 | 95,500,787 |
In electromagnetism, displacement current is a quantity appearing in Maxwell's equations that is defined in terms of the rate of change of electric displacement field. Displacement current has the units of electric current density, and it has an associated magnetic field just as actual currents do. However it is not an electric current of moving charges, but a time-varying electric field. In materials, there is also a contribution from the slight motion of charges bound in atoms, dielectric polarization.
The idea was conceived by James Clerk Maxwell in his 1861 paper On Physical Lines of Force, Part III in connection with the displacement of electric particles in a dielectric medium. Maxwell added displacement current to the electric current term in Ampère's Circuital Law. In his 1865 paper A Dynamical Theory of the Electromagnetic Field Maxwell used this amended version of Ampère's Circuital Law to derive the electromagnetic wave equation. This derivation is now generally accepted as a historical landmark in physics by virtue of uniting electricity, magnetism and optics into one single unified theory. The displacement current term is now seen as a crucial addition that completed Maxwell's equations and is necessary to explain many phenomena, most particularly the existence of electromagnetic waves. | <urn:uuid:8ea15a4f-5c98-4b82-a91e-9d582fac984e> | 3.640625 | 250 | Knowledge Article | Science & Tech. | 22.718568 | 95,500,812 |
Perl program to generate XKCD-style passwords
I want there to be NO barriers to using this code, so I am releasing it to the public domain. But "public domain" does not have an internationally agreed upon definition, so I use CC0:
To the extent possible under law, the contributors to this project have waived all copyright and related or neighboring rights to this work. In other words, you can use this code for any purpose without any restrictions. This work is published from: United States. The project home is https://github.com/fordsfords/pgen
To contact me, Steve Ford, project owner, you can find my email address at http://geeky-boy.com. Can't see it? Keep looking.
XKCD had an excellent comic -- https://xkcd.com/936/ -- which proposed a style of password generation consisting of randomly selecting 4 words from a list of ~2000 common words. The result is a password which is more secure and easier to remember than most common methods of password creation.
The pgen program downloads a list of common english words and randomly selects some for a password. I used the program to produce some mildly-interesting results in my blog.
Here are the interesting features of the program:
It starts with a set of 3000 words published by Education First and filters it by word length.
It can either use Perl's internal pseudo-random number generator (useful for experimentation and statistics gathering), or it can get random numbers from https://random.org which makes the resulting password properly secure.
You can get help by entering:
Important: if you plan to actually use the passwords you generate, use "-r"! Here's why.
2000.sh and 3000.sh
These shell scripts are not needed since I included code in the Perl program to fetch the Education First list. (The reason I do this is that the material on Education First's site is copyrighted, so I can't just snag a copy of their word list without permission.) | <urn:uuid:0f4e5b57-8013-4d45-8e01-1ee48c16a997> | 2.671875 | 422 | Personal Blog | Software Dev. | 61.742051 | 95,500,819 |
A new study in Alaska and Antarctica shows that the noisiest places in the ocean are where glaciers in narrow sea inlets called fjords melt into the saltwater, thereby liberating underwater gushes of bubbles that were once trapped in the ice.
According to research accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union, the underwater noise levels are much louder than previously thought, which leads scientists to ask how the noise levels influence the behavior of harbor seals and whales in Alaska’s fjords.
Researchers deploy a hydrophone into Icy Bay, Alaska. Scientists used the underwater microphones to listen and record the average noise levels in three bays in Alaska and Antarctica whose fjords have glaciers that flow into the ocean. They found that the noisiest places in the ocean are where glaciers in fjords melt into the saltwater.
Credit: Jeffrey Nystuen.
“The ocean ambient sound gives us clues to the physical processes going on, but it also is an important aspect of the environment in which marine mammals and fish live. Like teenagers at a loud rock concert, the seals and whales modify their behavior depending on the ambient sound levels,” said Erin Pettit, a glaciologist from the University of Alaska Fairbanks, Department of Geosciences. Pettit conducted the study with researchers from the University of Texas at Austin; the University of Washington, Seattle; and the United States Geological Survey.
The team used underwater microphones to listen and record the average noise levels in three bays whose fjords have glaciers that flow into the ocean – Icy Bay, Alaska; Yakutat Bay, Alaska; and Andvord Bay, Antarctica. All of the fjords have many icebergs where chunks of the glacier fell or calved into the water.
The researchers found that the average underwater noise level in these fjords was higher than any other source of ocean noise that has been measured so far including noise from weather, the movement and communication of fish, and human-generated noise from shipping and sonar devices. The team measured noise levels between 300 and 20,000 Hz, which is most of a human’s hearing range.
Glacier calving contributed to some of the noise, but the loud sounds were short-lived. When looking at overall noise levels for a long period of time, Pettit said it was the consistent melting of ice from the glacier and its icebergs that was the real noise generator. This is because the air trapped within the glacier ice escapes rapidly as it melts into saltwater, forming bubbles in the water that pop as they pinch off from the ice.
The black stars show that the underwater noise levels in Icy Bay, Alaska are significantly louder than noise levels caused by storms, melting sea ice or other sources of underwater noise. Credit: Erin Pettit
The black stars show that the underwater noise levels in Icy Bay, Alaska are significantly louder than noise levels caused by storms, melting sea ice or other sources of underwater noise.
Credit: Erin Pettit
Pettit said their findings raise questions about how the underwater noise in the fjords will affect animals as climate change first increases the rate at which glaciers melt into the ocean water and then stops the process altogether as the glaciers shrink and retreat onto land.
She said fjords with glaciers are foraging hotspots for seabirds and marine mammals as well as important breeding locations for harbor seals. One possibility, she said, is that the seals use the underwater noise to help conceal them from killer whales, which rely on listening to locate the seals. As glaciers retreat onto land, the seals would lose the acoustic camouflage, which might explain why harbor seal populations are declining in fjords where glaciers have retreated onto land, she said.
She said further studies are needed to investigate the relationship between the underwater noise levels and the fjord ecosystem. The team will continue listening to glaciers to see if they can develop a method of predicting glacier melt based on the underwater sounds.
The American Geophysical Union is dedicated to advancing the Earth and space sciences for the benefit of humanity through its scholarly publications, conferences, and outreach programs. AGU is a not-for-profit, professional, scientific organization representing more than 60,000 members in 139 countries. Join the conversation onFacebook, Twitter, YouTube, and our other social media channels.
Notes for Journalists
Journalists and public information officers (PIOs) of educational and scientific institutions who have registered with AGU can download a PDF copy of this article by clicking on this link: http://onlinelibrary.wiley.com/doi/10.1002/2014GL062950/abstract?campaign=wlytk-41855.5282060185
Or, you may order a copy of the final paper by emailing your request to Peter Weiss at firstname.lastname@example.org. Please provide your name, the name of your publication, and your phone number.
Neither the paper nor this press release is under embargo.
“Unusually Loud Ambient Noise in Tidewater Glacier Fjords: A Signal of Ice Melt”
Erin Pettit, Department of Geosciences, University of Alaska Fairbanks;
Kevin Lee, Applied Research Laboratories, University of Texas at Austin;
Joel Brann, Department of Geosciences, University of Alaska Fairbanks;
Jeffrey Nystuen, Applied Physics Laboratory, University of Washington, Seattle;
Preston Wilson, Applied Research Laboratories, University of Texas at Austin & Department of Mechanical Engineering, University of Texas at Austin;
Shad O’Neel, Alaska Science Center, United States Geological Survey.
Contact Information for the Authors:
Erin Pettit: +1 (206) 619-1752, email@example.com
+1 (202) 777-7507
University of Alaska Fairbanks Contact:
+1 (907) 474-7541
Peter Weiss | American Geophysical Union
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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Researchers from the Erasmus University in Rotterdam have demonstrated that a gene helps in the neat repair of DNA. Without this gene the body would repair damaged DNA in a careless manner more often. This causes new damage, which can lead to cancer.
The careless repair of damaged DNA can cause mutations and can result in cancer. Cell biologists from the Erasmus University in Rotterdam studied the repair of double strand breaks. Such breaks can for example arise following radiotherapy.
The researchers simulated radiotherapy by specifically damaging the DNA of mouse cells. Mouse cells in which the gene Rad54 was first inactivated, more often chose a careless means of repairing the damaged DNA. In normal mouse cells no more than 60% of the repairs are done in a careless manner, whereas in cells with an inactivated Rad54 gene this figure was about 80%.
The results show that the Rad54 gene is important for repairing breaks in a neat manner and for preventing mutations. The scientists hope that their findings combined with future research will lead to improvements in the treatment of cancer. In the meantime the researchers are examining patients who overreact to radiotherapy. The idea is that physicians could for example give milder radiotherapy to patients who lack the Rad54 gene.
Michel Philippens | alphagalileo
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
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Discussion of all aspects of biological molecules, biochemical processes and laboratory procedures in the field.
Moderators: honeev, Leonid, amiradm, BioTeam
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What are the difference in the material / method used when extracting DNA from bacteria, plant and animal cells?
- Inland Taipan
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Many kits used for DNA (plasmid ad/or genomic) extraction are the same. The only difference is usually located in the first steps: Cell lysis. procedure are diffrent for the diffrent kind of cells. After that, purification steps are usually identical.
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Earthquake and Volcano Deformation Hardback
by Paul Segall
Earthquake and Volcano Deformation is the first textbook to present the mechanical models of earthquake and volcanic processes, emphasizing earth-surface deformations that can be compared with observations from Global Positioning System (GPS) receivers, Interferometric Radar (InSAR), and borehole strain- and tiltmeters.
Paul Segall provides the physical and mathematical fundamentals for the models used to interpret deformation measurements near active faults and volcanic centers.
Segall highlights analytical methods of continuum mechanics applied to problems of active crustal deformation.
Topics include elastic dislocation theory in homogeneous and layered half-spaces, crack models of faults and planar intrusions, elastic fields due to pressurized spherical and ellipsoidal magma chambers, time-dependent deformation resulting from faulting in an elastic layer overlying a viscoelastic half-space and related earthquake cycle models, poroelastic effects due to faulting and magma chamber inflation in a fluid-saturated crust, and the effects of gravity on deformation. He also explains changes in the gravitational field due to faulting and magmatic intrusion, effects of irregular surface topography and earth curvature, and modern concepts in rate- and state-dependent fault friction.
This textbook presents sample calculations and compares model predictions against field data from seismic and volcanic settings from around the world.
Earthquake and Volcano Deformation requires working knowledge of stress and strain, and advanced calculus.
It is appropriate for advanced undergraduates and graduate students in geophysics, geology, and engineering.
Professors: A supplementary Instructor's Manual is available for this book.
It is restricted to teachers using the text in courses.
For information on how to obtain a copy, refer to: http://press.princeton.edu/class_use/solutions.html
- Format: Hardback
- Pages: 456 pages, 13 color illus.1 halftone. 269 line illus.
- Publisher: Princeton University Press
- Publication Date: 04/01/2010
- Category: Geophysics
- ISBN: 9780691133027
- PDF from £86.36 | <urn:uuid:24b0cf43-7ec8-4822-9bfa-11a282153bc8> | 2.5625 | 462 | Product Page | Science & Tech. | 19.762701 | 95,500,870 |
Jeremy Berg on 2009 Nobel Prize in Chemistry
Steitz on Nobel Prize Win
Nobel Foundation News Release
The Weizmann Institute of Science News Release
Timeline: 50 Years of Structure Determination
Ask the 2009 Nobelists a Question
Statement from the National Institute of General Medical SciencesOctober 7, 2009
The ribosome consists of RNA and 53 different proteins, making it complex and the largest structure yet determined by X-ray crystallography. Courtesy of Catherine Lawson, Rutgers University, and the RCSB Protein Data Bank.
Today’s Nobel Prize in chemistry recognizes groundbreaking structural biology research by Venkatraman Ramakrishnan, Ph.D., Thomas A. Steitz, Ph.D., and Ada E. Yonath, Ph.D. The National Institute of General Medical Sciences congratulates them on this honor. NIGMS has supported their work with more than $14 million in research grants since 1971, and total support from the National Institutes of Health exceeds $17 million.
The scientists were recognized for their “studies of the structure and function of the ribosome.” Ribosomes are the molecular factories that manufacture proteins in humans and other organisms. Knowing the structure and function of the ribosome has helped us understand one of life’s most fundamental processes and manipulate it—many of our antibiotics work by disrupting bacterial ribosomes.
For decades, the large size and complexity of the ribosome have complicated efforts to understand its innermost workings. Advances in high-resolution protein structure determination throughout the 1980s and 1990s, however, enabled the three Nobel laureates to generate key parts of the ribosome’s three-dimensional shape at the atomic level using a technique called X-ray crystallography. In later studies, the researchers produced structural models showing how different antibiotics bind to the protein-making machines. These accomplishments, which involved decades of painstaking research, ushered in a new era not just for protein studies, but also for studies of health and disease.
“When these researchers started their work, determining the structure and mechanism of the ribosome seemed nearly impossible,” said NIGMS director Jeremy M. Berg, Ph.D. “Their achievement shows how basic research to answer fundamental questions about biology also lays the foundation for medical advances.”
Since its creation in 1962, NIGMS has funded the Nobel Prize-winning work of 73 scientists, now including 35 Nobel laureates in chemistry.
More information about NIGMS support of Nobel Prize winners is available at /Education/pages/factsheet_NIGMSNobelists.aspx.
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June 28, 2018
Like our oceans, today’s continents are brimming with life. Yet billions of years ago, before the advent of plants, continents would have appeared barren. These apparently vacant land forms were believed to play no role in the early biochemical clockwork known as the nitrogen cycle, which most living things depend on for survival.
Now, Arizona State University researcher Ferran Garcia-Pichel, along with Christophe Thomazo, from the Laboratoire Biogéosciences in Dijon, France, and Estelle Couradeau, a former Marie Curie Postdoc in both labs, show that biological soil crusts — colonies of microorganisms that today colonize arid, desert environments — may have played a significant role in the Earth’s nitrogen cycle, helping to fertilize early oceans and create a nutrient link between atmosphere, continents and oceans.
Artist’s rendition of the environments of primeval earth in the Archaean, including the well-known aquatic stromatolites that are formed by carbonate-precipitating microorganisms. The close-up inset illustrates terrestrial biocrusts, typically organized by filamentous cyanobacteria, in a photograph of a modern sample. The new study suggests these biocrusts played a vital role in the nitrogen cycle of the early earth. Image credit: Estelle Couradeau
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Garcia-Pichel directs the Biodesign Center for Fundamental and Applied Microbiomics and is a professor in ASU’s School of Life Sciences. Originally, a marine microbiologist, he became fascinated with the hidden world of microorganisms that lay on top of soils in deserts and other arid regions devoid of plant life. These living biocrusts have remarkable properties, thriving in extreme conditions, helping to anchor soils in place, so they resist erosion, and fertilizing rangelands and deserts.
The new research, which appears in the advanced online edition of the journal Nature Communications, suggests that analogs of these biocrusts spread across otherwise desolate continents of the early Earth, and contributed to establishing the nitrogen cycle essential for life as we know it today.
“This really early Earth was a very different planet in many respects, particularly in the composition of the atmosphere,” Garcia-Pichel said. “Before the appearance of oxygenic photosynthetic microbes, like cyanobacteria that made oxygen — just like plants do today — the atmosphere was not oxygenated.”
This vast oxygen-free epoch lasted for half of Earth’s 4.6 billion year history.
All this changed with something referred to by geochemists as the Great Oxygenation Event.
“That was perhaps the single most important change in the nature of what the planet is. There are telltale signs of this in the rock record, so people have a good idea of when this happened — around 2.45 billion years ago, but conventional wisdom would have this happening in shallow oceans” Garcia-Pichel said.
Today, nitrogen makes up 78 percent of the atmosphere. It is a vital element in DNA, RNA and proteins, the key components of life. But the nitrogen found in the atmosphere is not suitable for use by most organisms. It must first be processed, through what is known as the nitrogen cycle. This occurs when prokaryotic organisms carry out nitrogen fixation, making atmospheric nitrogen available in a form useful to plants and animals for survival.
While it has long been assumed that the nitrogen cycle that arose early in the Earth’s history, resulted from oceanic microbes during an ancient phase known as the Archean, new research suggests significant amounts of nitrogen came from land-based biological soil crusts.
Ferran Garcia-Pichel directs the Biodesign Center for Fundamental and Applied Microbiomics and is a professor with ASU's School of Life Sciences.
“In the minds of many evolutionary biologists, the continents were irrelevant early in the Earth’s history, because they are assumed to have been barren of life until the first plants appeared, around 0.4 billion years ago. So all the models of how elements were cycled were based on interactions between the ocean and the atmosphere,” Garcia-Pichel said.
Recently however, evidence began to appear suggesting that the continents were far from the sterile land masses they had been portrayed as. Instead, intricate microbial communities similar to biocrusts found in present-day desert environments, colonized the early continents. Traces of their presence date to 3.2 billion years ago, well before the Great Oxygenation Event helped set the stage for the Cambrian explosion — a sudden burst of life that gave rise to most of the world’s animal phyla.
The researchers note that today, such biocrusts occupy roughly 12 percent of the Earth’s land. They are composed of filamentous cyanobacteria, which perform most of the biocrust’s carbon and nitrogen fixation and provide nutrients to the rest of the crust microbiome, while bonding soil grains together and providing microbial communities with erosion resistance.
“These communities live on light,” Garcia-Pichel said. “When plants evolved and started to accumulate, this marked their demise. There’s no light on the soil anymore because of plant litter accumulation”.
However, in an early world, before the evolution of plants, there would be nothing to impede their colonization of the continents, where conditions for their growth and development would have been considerably less harsh.
As Garcia-Pichel notes, watery environments like oceans and lakes provide superior conditions for fossilization, making the detection of ancient biocrust colonies on land more challenging. This may account in part for the neglect of continental biocrusts as the primeaval land-based ecosystems for much of the planet’s history.
A new picture emerges
The team carried out a meta-analysis of their earlier data combined with other relevant literature on the cycling of nitrogen by modern biocrusts. Results demonstrate that nitrogen-cycling biocrusts are capable of importing nitrogen gas from the atmosphere and exporting ammonium and nitrate.
Quantitative analysis suggests that biocrust contribution to nitrogen cycling during the early history of the Earth would have been significant, even with limited colonization of the pre-Cambrian continents.
The notion of land-based life forms — the biocrusts — providing a significant contribution to the Earth’s early biogeochemistry represents a significant paradigm shift. New research should help establish just how far back in Earth’s record these microbial biocrusts extend and help explore their contributions to the cycling of other elements, like phosphorus.
Garcia-Pichel’s center is also involved in efforts to restore biocrust communities in desert environments, where urbanization and other factors have seriously degraded them. While these communities show astonishing resilience to the harsh conditions of both desert and polar regions, they are highly sensitive to human interference, including trampling, vehicle traffic and agriculture.
Garcia-Pichel estimates that in the areas around Phoenix, where he works, only 5 percent of the original biocrusts remain. Further, climate change will not only alter the demographics of biocrusts, which vary in their composition according to region, but will render some desert environments too severely arid for their survival. Restoration of these communities is currently a challenging undertaking, part science and part art. The right mix of microbial players must be present for newly seeded communities to survive and flourish.
“When you destroy the crust, you make the soil unstable and very prone to erosion,” Garcia-Pichel said. “Areas that are deforested of crusts are sources of fugitive dust and sand. The natural protection of the desert is not there, and even moderate winds can raise a haboob. We have been funded for the last 5 years to develop ways to grow these crusts and reseed them in the field. That’s an applied part of our work, which is a new thing for our lab.” | <urn:uuid:41a74b72-1310-48e0-b1f5-9811dfbafba1> | 3.953125 | 1,680 | News (Org.) | Science & Tech. | 29.09647 | 95,500,881 |
Use your skill and judgement to match the sets of random data.
In this short problem, can you deduce the likely location of the odd ones out in six sets of random numbers?
Which pdfs match the curves?
Does weight confer an advantage to shot putters?
Who will be the first investor to pay off their debt?
How do you choose your planting levels to minimise the total loss at harvest time?
Starting with two basic vector steps, which destinations can you reach on a vector walk?
See how enormously large quantities can cancel out to give a good approximation to the factorial function.
Can you sketch these difficult curves, which have uses in mathematical modelling?
Go on a vector walk and determine which points on the walk are closest to the origin.
Explore the meaning of the scalar and vector cross products and see how the two are related.
Can you make matrices which will fix one lucky vector and crush another to zero?
10 graphs of experimental data are given. Can you use a spreadsheet to find algebraic graphs which match them closely, and thus discover the formulae most likely to govern the underlying processes?
Have you ever wondered what it would be like to race against Usain Bolt?
Various solids are lowered into a beaker of water. How does the water level rise in each case?
Which of these infinitely deep vessels will eventually full up?
Why MUST these statistical statements probably be at least a little bit wrong?
Which line graph, equations and physical processes go together?
Use vectors and matrices to explore the symmetries of crystals.
Explore the properties of matrix transformations with these 10 stimulating questions.
Work out the numerical values for these physical quantities.
Many physical constants are only known to a certain accuracy. Explore the numerical error bounds in the mass of water and its constituents.
Explore the meaning behind the algebra and geometry of matrices with these 10 individual problems.
In Fill Me Up we invited you to sketch graphs as vessels are filled with water. Can you work out the equations of the graphs?
Formulate and investigate a simple mathematical model for the design of a table mat.
Can you work out which processes are represented by the graphs?
Simple models which help us to investigate how epidemics grow and die out.
What shapes should Elly cut out to make a witch's hat? How can she make a taller hat?
Explore the properties of perspective drawing.
Looking at small values of functions. Motivating the existence of the Taylor expansion.
How would you design the tiering of seats in a stadium so that all spectators have a good view?
Can you work out what this procedure is doing?
Get some practice using big and small numbers in chemistry.
Could nanotechnology be used to see if an artery is blocked? Or is this just science fiction?
Explore how matrices can fix vectors and vector directions.
Can you construct a cubic equation with a certain distance between its turning points?
Invent scenarios which would give rise to these probability density functions.
This is our collection of tasks on the mathematical theme of 'Population Dynamics' for advanced students and those interested in mathematical modelling.
Use the computer to model an epidemic. Try out public health policies to control the spread of the epidemic, to minimise the number of sick days and deaths.
To investigate the relationship between the distance the ruler drops and the time taken, we need to do some mathematical modelling...
A problem about genetics and the transmission of disease.
Explore the shape of a square after it is transformed by the action of a matrix.
How much energy has gone into warming the planet?
In this short problem, try to find the location of the roots of some unusual functions by finding where they change sign.
Match the descriptions of physical processes to these differential equations.
Each week a company produces X units and sells p per cent of its stock. How should the company plan its warehouse space?
By exploring the concept of scale invariance, find the probability that a random piece of real data begins with a 1.
Can you find the volumes of the mathematical vessels?
Work with numbers big and small to estimate and calulate various quantities in biological contexts.
Estimate areas using random grids | <urn:uuid:445d463e-3a94-4b43-b416-959b5f35c3ee> | 3.171875 | 876 | Content Listing | Science & Tech. | 51.762009 | 95,500,884 |
In crystallography, a vacancy is a type of point defect in a crystal. Crystals inherently possess imperfections, sometimes referred to as crystalline defects. A defect in which an atom, such as silicon, is missing from one of the lattice sites is known as a 'vacancy' defect. It is also known as a Schottky defect, although in ionic crystals the concepts are not identical. Vacancies occur naturally in all crystalline materials. At any given temperature, up to the melting point of the material, there is an equilibrium concentration. At the melting point of some metals the ratio can be approximately 1:1000. It is the simplest point defect. In this system, an atom is missing from its regular atomic site. Vacancies are formed during solidification due to vibration of atoms, local rearrangement of atoms, plastic deformation and ionic bombardments. The creation of a vacancy can be simply modeled by considering the energy required to break the bonds between an atom inside the crystal and its nearest neighbor atoms. Once that atom is removed from the lattice site, it is put back on the surface of the crystal and some energy is retrieved because new bonds are established with other atoms on the surface. However, there is a net input of energy because there are fewer bonds between surface atoms than between atoms in the interior of the crystal.
The numerical value of vacancy defect in Chaldean Numerology is: 4
The numerical value of vacancy defect in Pythagorean Numerology is: 4
Images & Illustrations of vacancy defect
Translations for vacancy defect
From our Multilingual Translation Dictionary
- रिक्ति दोषHindi
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"vacancy defect." Definitions.net. STANDS4 LLC, 2018. Web. 16 Jul 2018. <https://www.definitions.net/definition/vacancy defect>. | <urn:uuid:448e7315-55f8-4043-816f-a6b979941213> | 3.796875 | 470 | Structured Data | Science & Tech. | 36.706177 | 95,500,886 |
Hank explains the science behind recent reports that physics great Stephen Hawking said "there are no black holes." There are. They're just super complicated.
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What if the ejection from a black hole is actually a blast from a new big bang of a new universe being created? Eventually it closes itself off leaving nothing but cosmic radiation, which would be that universes dark ages (around 3800,000 years after the big bang). Some universes would make it. Maybe every black hole is a universe generator. Maybe I'm smoking too much.
I am submitting this question for the second time(first here). If you were to enter a black hole below the event horizon, could this possibly be a form of entering into a time warp/wormhole? May be a silly question which has no merit.
rule 1: there is a black hole
rule 2: everything goes in, nothing comes out
rule 3: it keeps sucking and sucking
rule 4: it will grow
if it kees growing - how big will it be in 1000 years, 2000 years
if it has been growing, how strong will the black hole be
and will this result in accelleration of the process..
if this was true.. why are we here.. and not sucked up.. by a blackhole ?
So, the blackhole must leak and fade .. in a curved morgage model
aka, it will be losing more and more mass in time.. slowing down the effect of
the "apparent" horizon.. and then.. will it become a star..or.. a scar ?
up,down, equal - it can grow due to added information
it can shrink by losing information
it can stay the same - but why ?
the escaped data.. is :
mangled data - not in the format as it wend in ?
from initial escape point the laws of physics apply ?
very elementary particles fuse to the next level of weight ?
new elements are created ?
is the escaped matter radio active ?
will it decay fast, moderate, slow ?
will it do fast, moderate and slow in some specific spread spectrum ?
will the escaped stream trigger the creation of stars ?
but if black holes lose matter and therefore mass over time, if after some million of years it has lost enough mass that it's gravity is no longer strong enough to absorb ALL light then wouldn't it slowly devolve into some sort of dead star matter that a future human can observe?
God says in the holy Quran what means [So verily, I swear by the stars that are veiled . And by the (sweeping ) stars that move swiftly and hide themselves. And by the night as it departs; And by the dawn as it brightens; Verily, this is the Word (this Qur'an brought by) a most honorable messenger [Jibril (Gabriel), from Allah to the Prophet Muhammad (Peace be upon him)].] (chapter At-Takwir: verses 15-19)
It seems time is a man made up idea. Perhaps there are places where time does not exist, perhaps one could move or view time front to back, back to front. Hmmm, now that brings up a lot of questions. Gives me a head ache, and I am only an engineer person....Anyone have an Excedren!
As I understand it, black holes evaporate, which is where Hawking Radiation comes from. It’s basically “steam” from all that matter being compressed into a teeny point. Once the black hole has run out of fuel, it stops emitting Hawking Radiation, the event horizon dissipates, and all that is left is... we don’t know yet. Ash? A diamond-like particle of super compressed matter? But it’s not lost, only changed.
Basically, Hawking said that black holes are temporary, not eternal. They’re more like a forest fire that is deadly but not forever.
Greg Lives25 minutes ago.Since we live in virtual reality, huge forces are just data; universe is being run by super computers that convert data into our physical world & back to data, both at the event horizon. The event horizon is your 2D holographic medium. Physicists (Hawking) conjecture that things that fall into black hole are extinguished while data (info of the matter) is left on event horizon. Conjecture- event horizon is like holographic film A super dude is creating these holes with computer like device, but since he isn't IN the universe, he is using DATA( in a computer ) which create virtual forces, virtual matter & virtual beings (US) after passing through the event horizon. He is also removing/destroying things via black hole (which converts into computer code- 1s & 0s). Some info stored on event horizon, other info saved somewhere in superdudes computer. If you are creating a virtual reality, those 1,000,000 degrees of heat in suns in our reality has no intrinsic value to the maker other than code. At black hole code applied to event horizon= virtual creation; Matter/forces of our reality sucked in at event horizon are broken back into code. To superdude it is just numbers- ( furious winds in video games are just numbers in a computer. When you play video, are you ever effected by anything in the game like a video character is?- NO. No Thor Hammer or Panzer tank can touch you. Work this concept.
Here's a stumper. All people see everything their whole life in small area at the back of brain. What theorists are saying "the wave functions are collapsed by observing, which solidifies the object" in the outside world. But does it. Where do physicists make these measurements? Where is this "outside" world? In A building called university or are they all in their own little visual cortex where things aren't outside of anybody. Everyone collapses wave function in the brain, but you are tricked into believing it's outside your body.
Here is scenario- physicists all seem to be going to work; working projects, making measurements on experiments, but it's an illusion. No one leave a spot, because no spot actually exists- all illusion. So, observers aren't collapsing waves outside of them, but the waves inside their head which solidifies their "reality"; a reality which seems to be shared with other beings- connected visual cortex to visual cortex in some manner. Is there an outside world? Seems not. Everything can happen in each person's visual cortex which gives the illusion you are seeing outside yourself. `
1st, the idea that black holes have an infinitely small singularity of an infinite mass should had caused mass-puking in the schientific comunity from the early 60s. It starts from a finite ammount of mass (a star), gulps a bit more along the way and that‘s that. No infinity. Big, yes, not that big.
2nd, obviously there are no black holes. Because it would be a pleonasm and racist.
THERE IS SIMILARITY BETWEEN BLACK HOLE AND MATTER.
If a photon emerges when a positron and an electron collide, it means that the electron and the positron are formed by means of an "oscillation trap" which does not allow the photon to escape like a black hole. In this case, there is a functional similarity between an electron and a black hole. There may be a structural similarity between black hole and matter.
Why do not physicists think it? If the only thing that is not an antiparticle is photon, does not it mean that this photon is the most massive building stone? Everything be consist of different oscillation of photon. An interpretation of Einstain equation for E = m.c ^ 2 tells us that everything has come to light. In this caseIs matter acctually a formation of black hole in a sense?
So if hawking was proposing that the apparent horizon will evaporate when the black hole radiates out all of its energy. Wouldn't that leave the possibility that a very long time ago all black holes came together and when it radiated away the big bang happened?
I read a remarkably clever SF story, in "Analog" magazine I think, in which a future nuclear fusion power plant, using some ferocious heavy hydrogen compression mechanism, creates a small Black Hole. The reporter goes to the best qualified physics professor he knows, and they conclude that a Black Hole will eat its way to the center of the planet, and go on eating. It's the End of the World! The reporter files his story electronically, and remembers he didn't answer the question "When?"
He goes back the the professor, who has also been thinking about it, and this story having been written not very long after Hawking published his conclusions about the relationship between the mass and the lifetime of a Black Hole, it turns out that any Black Hole of the mass of the entire Earth would be very evanescent.
Should the reporter be consoled for the ignominy that his greatest story ever is false, by the fact that the End of the World actually hasn't arrived?
If a black hole condenses matter into an infinitely small point, wouldn't that be 1 dimensional? And we live in a 3 dimensional universe, which makes a 1 dimensional object, the black hole, physically impossible.
I'm no scientist, and would love if someone who actually knows what they're talking about to correct me.
Blackholes r just ultra dense & ultra hot things period. Just like base of oceans r ultra high pressure. Interestingly if u put solid objects at base of ocean their volumes indeed decrease ie their densities increse. Just extrapolate this phenomenon & u get blackholes. They r no mysteries.
I would love to hear SciShow's take on Eternally Collapsing Objects (ECOs), the so-called quasi black holes and further Magnetospheric Eternally Collapsing Objects (MECOs). Since some Relativists consider mathematical black holes (the ones having a singularity at the centre) to not exist in nature (separation of mathematical concepts from physical reality) it would be interesting to hear about ECOs which are an alternative explanation for our observations of black holes.
How to become bitcoin trader? Exactly like Bitcoin, multiple digital currencies exist in the marketplace. So if you prefer to buy a few other currencies which aren`t available on Indian Exchange than you can utilize Bittrex. All you have to do is locate an exchange that you favor. Cryptocurrency exchanges have a massive potential to modify peoples minds and opinions concerning cryptocurrencies generally speaking and their application in actual life. So even in the event the exchange is attacked, its still true that you have your money. Furthermore, the exchanges prepare each and every industry for Bitcoin expansion. Existing stock exchanges will also compete to be able to fulfill the users configuration requirements. Sooner or later later on, the prices will grow more equal, meeting somewhere in the middleyour profit is equivalent to the quantity of convergence. No matter how far it is from Kijun, it is likely to return and test that level at some point. The amount of bitcoin is perpetually changing. In the US, it is 1000 USD. Whats even better, seek the services of a seasoned lawyer or at least ask for an in depth consultation. So youve read the newspaper about the meteoric growth of crypto currencies including Bitcoin or Ripple. Then coming up with 1000s of exchange rates simply to go out and get groceries is nearly impossible. Many cities around the world provide a bitcoin ATM where you are able to trade cash for bitcoin. The cryptocurrency world isn`t efficient. | <urn:uuid:9ac758ad-40df-4de1-a82a-7a2c436dae3f> | 2.890625 | 2,549 | Comment Section | Science & Tech. | 56.206031 | 95,500,892 |
Assume that the genes for tan body and bare wings are 15 map units apart on chromosome II in Drosophila. Assume also that a tan-bodied, bare-winged female was mated to a wild type male and the resulting F1 phenotypically wild type females were mated to tan-bodied, bare- winged males. Of 1000 offspring, what would be the expected phenotypes and in what numbers would they be expected?© BrainMass Inc. brainmass.com July 18, 2018, 6:31 am ad1c9bdddf
Number of recombinants is directly proportional to the distance between genes in map unit. This relationship is utilize in calculating the number of phenotypes. | <urn:uuid:99b976eb-98f0-479a-ab35-d2ef057f6ad5> | 2.90625 | 147 | Tutorial | Science & Tech. | 47.772308 | 95,500,917 |
- 1 Recycling of early productive nanosystem products
- 2 Biodegradable diamondoid products
- 3 Recycling of diamondoid AP structures
- 4 Bringing carbon back to the biosphere
- 5 General
Recycling of early productive nanosystem products
Technology level I
Most materials used in early bio based productive nanosystems (naturally occurring and or artificially synthesized organic molecules -- e.g. DNA) are completely bio degradable. Recycling can be done by nature (composting).
Possible problems may be:
- waste molecules from medical applications causes hormone like effects (a known and already existing problem)
- accumulation of artificially synthesized persistent organic molecules in the environment (TODO: reference related video) (thy are called persistent organic pollutants or POPs). Note that the volumes of waste molecules produced in the early stages of APM probably won't be very high. So low toxicity POPs may not be much of an issue at first if by the time when the production volumes explode other less problematic materials with superior mechanical properties (bio-minerals) already have taken take over.
Technology Level II
Bio-minerals that might be used by an intermediate level of productive nanosystem stay around longer than the well biodegradable organic molecules. Bio-minerals already are present in enormous masses. These are materials where nature knows how to deal with them.
Possible problems may be:
- High salt concentration (various salts meant here not NaCl) when large amounts are dumpt at one place
- The volumes of bio-mineral production and recycling issues are yet hard to predict.
Technology Level III
- gemstones (e.g. Diamond) e.g. don't really decay. This is good for engineering but bad for nature. Nature is used to deal with large chunks of gemstones. Advanced nanosystems will contain nanoscale gemstones (here called crystolecules) though that may come loose in bad system designs. There might be some exotic microorganisms capable of degrading diamond (TODO: research that) and they might start to evolve with massive availability of diamond but much more likely is that we will much sooner start to attack our own stuff.
Read more on recycling of advanced nanosystems further down.
Biodegradable diamondoid products
For lower performance applications (that is most applications) the probably earlier accessible materials that are significantly weaker than diamond may be sensible to keep even in the more advanced products. Some examples are periclase calcite/aragonite and quartz.
It is not yet clear whether advanced atomically precise products can be made exclusively out of these biodegradable materials while retaining similar density of nanomechanical structures to products out of diamond. The main issues with these materials are:
- sliding surfaces of crystolecules (for bearing applications) made from this materials have not yet been simulated. Ionic bond character is likely to make sliding interfaces harder to design or even impossible. Extremely ionic materials like stone salt could still be used as structural materials.
- If the product continuously decays it needs a sacrificial protection layer facing the environment. It is not yet clear whether a metamaterial hull can be designed that seals the interior is flexible and does not gunk up too badly when some parts are dissolved and recrystallized all over the place. A biodegradable gem-gum-skin e.g. "limestone rubber". If that works one can begin to think about fantastic things like active hull regeneration.
There seem to be no diamondoid carbon based materials (excluding 2D graphite) that decay in reasonable time-spans. (Counterexamples appreciated!) Materials that decay slowly are best. This way non carbon metal cations have time to wash out of organic soil and do not reach problematic concentrations like it is e.g. the case of the use of thawing-salt NaCl for de-icing.
Including non degradable parts in degradable matrix will lead to a situation where remnant "bones" or worse release of persistent nano-particles occur. See: Mobility prevention guideline
Recycling of diamondoid AP structures
Usage of microcomponents for better reusability
Diamondoid mechanosynthesis is an irreversible process (TODO: relativate that). Once a DME is assembled it can not be taken apart again (see atomically precise disassembly). The only way for the bound carbon back to the biosphere is by burning it at sufficiently high temperatures (See the speculative: "hot gas phase recycling cycle"). What will help alleviating this problem is the organisation of APM products into microcomponents (which are quite a bit bigger than DMEs) that can reversibly be joined together and thus can potentially be reused and recomposed. More about those microcomponents can be found on the "assembly levels" page. Microcomponents only need to run through the upper basic assembly levels of a nanofactory (microcomponent recomposer) to get recomposed to a different product.
Tagging microcomponents can help to successfully salvage microcomponents from macroproducts that became singed or broken with random fracture plane.
Inter microcomponent joints that do not destroy themselves (or some of the involved microcomponents) when ruptured are preferable in most applications where maximum strength isn't a necessity (splinter prevention). For this either trivial sticking of coplanar surfaces (Van der Waals force) or specially designed controlled breakage locking mechanisms suffice. If the joints are too weak and do not break in big chunks collectively (through whatever implemented mechanism) rub-off microcomponent dust may be an health issue.
Reuse of microcomponents
Assuming a speculative global microcomponent redistribution system will come into existence then for big immobile objects beyond the weight of an adult person (like buildings) it may be possible to "suck" them away if they are no longer needed. For everyday sized objects running arround having them physically tethered to such a network will often not be possible (e.g. backpacks, drinking cans, ...).
Early lockout fosters better reusability
The nanofactory design can have a drastic influence on the degree how much recycling actually gets realized.
If a nanofactory does vacuum lockout from seperate compartments at the soonest possible moment in the convergent assembly chain - that is as soon as all open radicals are closed - the products are enforced to consist of microcomponents which are potentially recylable by recomposition into other patterns. The downside is that you have to deal with dirt.
If a nanofactory does convergent assembly right up to the full product size it can (it does not necessarly need to but it makes sense) delay the final vacuum lockout right to the very end of the production. If intermediate vacuum lockout layers are omitted the product might be a monolithic diamondoid block that can't be recycled at all and is probably hard to burn too. The reason why this is attractive for developers is that you can simplify design when you don't have to deal with dirt and grit.
One could call a nanofactory that is a failure in this regard an "eternal waste brick nanofactory" if such a design is the first one to spread massively it could mean disaster.
Reversibility of larger scale connection mechanisms ist a necessity for recycling. The original fir tree interlocking expanding ridge joint connection mechanism design by Eric Drexler is irreversible. A reversible version would be highly desirable.
Recycling of crystolecules
Using the principle of shape locking combined with the principle of reinforcement allows to build up systems from viewer smaller less complex and thus better reusable standard crystolecule-component-types (See: Structural elements for nanofactories for details). Normally one will recompose only fully passivated crystolecule-components where practically perfect vacuum is not an absolute necessity (no vacuum lock-in -- which is much harder to do than vacuum lockout) but practically perfect vacuum. It might be advisable to design composable sets of crystolecule-components in such a way that they are tolerant to a few stray molecules (both reactive oxygen and nonreactive argon - think wrench in the gears) that may get enclosed accidentally. This way it won't be necessary to lock in the crystolecules all the way back to the level of practically perfect vacuum.
Preference of machine phase
See: The mobility prevention guideline.
Beside being a necessity for APM in all technology levels but t.level 0 keeping everything in machine phase also prevents spill of AP micro- and nanoparticles (that is microcomponents and DMEs) in the envirounment. The rule to never let go of diamondoid products (never let them escape the machine phase) to keep the biosphere clean obviously has to be dropped at some size level arond the millimeter scale though. In many cases its convenient when makro products come preassembled (laptop) but there are also cases where finding the most pleasing form of assembly is most intuitive and easiest done by hand (art). Such manual assembly of diamondoid AP products will maybe be doable by e.g. (speculative) quasi welding.
- semi-intelligent microcomponent metamaterial designed to allow abrasion only in big chunks ?
- Soft cables and sheets
Bringing carbon back to the biosphere
It's not easy but there is motivation to create specialized equipment for the synthetisation of molecules that are edible by humans. Since many other species will be able to digest them too carbon (e.g. in ethyne form) could be gently spliced back into the biosphere that way.
Advanced well designed AP Technology will probably greatly reduce the amount of waste that escapes in the environment. (Speculative) The most critical time is maybe when technology level III arrives but is not yet advanced. Recognizing and cropping out nests of damaged microcomponents will be a rather nontrivial problem. See "self repairing systems".
Production of waste that is irrecoverable at its production time is unavoidable.
Even nature lacking human influence faces this problem. See: great oxygenation event (wikipedia) and the accumulation of lignin in the carboniferous period until fungi figured out how to break it down (wikipedia)
What we can do is to try to limit the rate of irrecoverable waste production to such low levels that technology is likely to catch up to that challenge before the pollution grows beyond all bounds. Something like a dynamic equilibrium. (Is there a general principle waste removal capability always lags behind waste production capability? - Just guessing.) | <urn:uuid:7033c020-a9d9-4b63-b9a1-c8de8d32f031> | 3.34375 | 2,224 | Knowledge Article | Science & Tech. | 26.644193 | 95,500,926 |
Authors: George Rajna
Fusion may have a dark side. A shadowy hypothetical process called “dark fusion” could be occurring throughout the cosmos, a new study suggests. A recent astronomical observation that the ordinary matter in the early universe was much cooler than expected could be explained if a small proportion of dark matter has a tiny electric charge. This week, scientists from around the world who gathered at the University of California, Los Angeles, at the Dark Matter 2018 Symposium learned of new results in the search for evidence of the elusive material in Weakly Interacting Massive Particles (WIMPs) by the DarkSide-50 detector. If they exist, axions, among the candidates for dark matter particles, could interact with the matter comprising the universe, but at a much weaker extent than previously theorized. New, rigorous constraints on the properties of axions have been proposed by an international team of scientists. The intensive, worldwide search for dark matter, the missing mass in the universe, has so far failed to find an abundance of dark, massive stars or scads of strange new weakly interacting particles, but a new candidate is slowly gaining followers and observational support. “We invoke a different theory, the self-interacting dark matter model or SIDM, to show that dark matter self-interactions thermalize the inner halo, which ties ordinary dark matter and dark matter distributions together so that they behave like a collective unit.” Technology proposed 30 years ago to search for dark matter is finally seeing the light. They're looking for dark matter—the stuff that theoretically makes up a quarter of our universe. Results from its first run indicate that XENON1T is the most sensitive dark matter detector on Earth.
Comments: 45 Pages.
[v1] 2018-06-07 05:51:05
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Boivin S, Saucède T, Laffont R, Steimetz E & Neige P (2018). Diversification rates indicate an early role of adaptive radiations at the origin of modern echinoid fauna. PLoS ONE 13(3): e0194575
Les résultats de cette étude mettent en évidence l’existence de deux radiations évolutives contemporaines au sein des oursins irréguliers jurassiques, chacune étant associée à une forte diversification fonctionnelle, en accord avec l’hypothèse de radiation adaptative…
L’article “Adaptive radiation in the fossil record: a case study among jurassic ammonoids” par P. Neige, G. Dera & J.L. Dommergues, vient d’être publié dans Palaeontology (online publication).
Evolutionary radiations have been extensively studied especially in the fossil record and in the context of post-crisis recoveries. The concept of adaptive radiation that emerges from this very broad topic explicitly involves the effect of adaptation driven by ecological opportunity and is considered to be of the foremost importance. It is essential to be able to detect adaptive radiation because it points up factors that predispose a clade to radiate. Adaptive radiation has received much attention in recent decades based mostly on studies dealing with Recent clades, but data from the fossil record are still scarce. The present study begins to fill this gap with the example of Lower Jurassic ammonoids (through c. 8 Myr of history). A survey of several clades, using both taxonomic and disparity-based approaches, shows that they diversified successively through time, but not systematically, in terms of species numbers and morphological variety. Some clades seem to have exhibited adaptive radiation and to have become rapidly extinct. One clade (which engendered nearly all post-Lower Jurassic ammonoids) has a fossil record that begins with low diversity and disparity but is superseded by a sustained radiation pattern. The results are discussed in the light of the Modern Synthesis and its continuation into an Extended Evolutionary Synthesis. | <urn:uuid:9c67eb36-42e7-4b15-a571-cc37c1025d24> | 3.1875 | 467 | Academic Writing | Science & Tech. | 21.376174 | 95,500,980 |
Our experience with Domain Events
Our experience with Domain Events
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Domain-Driven Design background
There are a series of Domain Model patterns that describe objects and objects group built with Domain-Driven Design. Aggregates describe cohesive object graph with a single point of entry, called root: the internal objects of the aggregate cannot be persistently references from the outside.
The domain classes whose instances are inside aggregates are subdivided into Entities and Value Objects: the former have a lifecycle (like a Post or a User), while the latter are just values with methods, equivalent to Strings and other domain concepts.
A prerequisite of these patterns is the immutability of Value Objects, which can then be shared between aggregates, just like String instances can be in many languages. Value Objects such as numbers and colors are modified by calling a method on them that return a new instance: every change to their state should produce a new Value Object.
Repositories are collection of aggregates: they model operations such as finding an aggregate or persisting a new one.
A great departure of modern DDD from the entity/relationship modelling everyone knows is the duplication of data between aggregates to support new scenarios: it's possible some field or object is repeated in different aggregates. When there is an update to an aggregate, it's not necessarily atomically reflected to the other copies of its data.
I'll refer to writing calls for generality, to indicate the Command side of the Command Query sepration, which corresponds to everything that causes a change in state in the domain objects (in opposition to the reading side).
Events as mail messages
Thus it has become common to copy data between objects in different aggregates: for example, think of a Document and Invoice object that share the same start/finish date interval. Traditionally this duplication is dealt with by extracting a common object, mapped to a common row in the database, with a name invented on the spot.
Domain events are an alternative that allows for duplicating these data: they reflect changes happened in a single aggregate, and are sent to other aggregates so that they can update themselves. Technically speaking, domain events are Plain Old $YourLanguage Objects, containing the modified data but not related to the ORM like the main domain objects.
Domain events are handy for modelling "when" rules that should always be respected no matter who is writing to an aggregate; moreover, their handling can take place in the same transaction or even in a new one.
My skeptic view of events was that it can be unclear which events are communicated between objects. After a while, I accepted that unit tests tell us that; moreover, communicating with events is a further level of abstraction which is unnecessary in simple domains but just a giant Observer pattern in others.
The underlying idea is that no matter who applies a command or modifies a domain object, we already configured the event handling mechanism so that consistency across aggregates is reached according to our policy defined in the event handlers (which may be immediate consistency, or eventual one. Or it may result in sending a mail to a human asking him to review the changes: whatever you want.)
The only alternative to propagate changes between aggregates would be to have many collaborators passed to the various Repositories, but this solution couples the aggregates with each other in many way, while with events you're forced to define one-way messages. The event generator does not make any assumption about who will listen to the event and if it will be listened to at all: events are a point of decoupling like interface are for object collaboration.
And it's not that we call static methods by passing a string. We have a clear contract, a DomainEvents static class, and we publish interesting events (like CreatedCar or UpdatedVoyagePlan) as plain old domain object which contain all the information about the update, often even composing the relevant domain object.
Udi Dahan discourages the reference to domain objects, and consider events just special Value Objects; indeed as our solution matures we are moving towards simpler objects. This choice may force us to consider just what needs to be inserted in the message instead of a full reference (where and if serialization is used to transmit the event, it's simpler to use a Value Object in fact). Moreover, it avoids possible further accidental writing calls to the domain object originating the event.
In the application layer
Events are published by calling a static domain class: as a result event launchers cannot be decoupled from the event (as in Udi Dahan's approach).
We launch events from the Repository after an update has been performed, either by choosing an event class directly (in case of an update or creation) or by collecting the events from a queue on the relevant domain object, usually the root of the aggregate. This was a nice idea from a colleague of mine that let us decouple at least Entities from the DomainEvents static class.
For now we do not have the requirement to decouple the handling of events from the transaction, so the application layer (which is over the domain layer) open and commits/aborts a transaction, while reconstituting an aggregate, doing some "writing" work (updating it or executing a Command) and saving it. The save triggers the event launch, which may trigger work on other aggregates through the configured handler: in case of an error the whole transaction is aborted, ensuring immediate consistency.
So we aren't getting the scaling advantages of deferred handling (we're not interested in that for now), but the simplicity of communicating with events while writing code.
This a PHP-specific section: however, domain events are an approach typical of Java or .NET enterprise applications.
We use PHP classes (or interfaces) for routing the events with instanceof; PHP is a shared nothing environment, so event configuration is done now on a per-action basis to avoid having to create all the objects handling events on each request.
However, we want to move the configuration to the application level, with some lazy-loading: for example, configuring lazy event handlers as methods on Factory objects that create the real handler and return it along with the name of the method to call. All communication between aggregates happen in a single process and a single address space (for now), so we don't use a bit of the decoupling properties of events.
We map Value Objects into the relational database either as on the parent entity's table (decomposing their fields onto the entity) or as row of their own table. In any case, we have to ensure immutability via encapsulation and only assignign to $this->anyField into the constructor.
Our standard pattern is to define setters as new self($this->field1, ..., $nwFieldValue, ..., $this->fieldN); where N is a small number of fields. We map all domain object with the Hibernate-equivalent Doctrine 2. We are investigating how to deal with orphaned Value Objects, which are not reached anymore by any other entity.
Opinions expressed by DZone contributors are their own. | <urn:uuid:e9c5b9df-59fc-4800-b18c-4e74ec995792> | 2.703125 | 1,503 | Truncated | Software Dev. | 30.446704 | 95,500,992 |
Comparable module gives other classes comparison operators such as
The Comparable module uses the <=> comparison operator on the class that includes it.
<=> returns -1 if the supplied parameter is higher than the object's value, 0 if they are equal, or 1 if the object's value is higher than the parameter.
1 <=> 2 #-1 1 <=> 1 #0 2 <=> 1 #1
class Song include Comparable # from w w w . j a v a 2s .c o m attr_accessor :length def <=>(other) @length <=> other.length end def initialize(song_name, length) @song_name = song_name @length = length end end a = Song.new('Rock around the clock', 143) b = Song.new('Bohemian Rhapsody', 544) c = Song.new('Minute Waltz', 60) puts a < b puts b >= c puts c > a puts a.between?(c,b)
You can compare the songs as if you're comparing numbers.
By implementing the <=> method on the Song class, individual song objects can be compared directly. | <urn:uuid:4f0973ae-1bf8-40a7-b5c2-9b30e41d28b0> | 3.953125 | 248 | Documentation | Software Dev. | 78.559422 | 95,501,003 |
China is set to launch a space telescope, the Hard X-ray Modulation Telescope (HXMT), to observe pulsars in the galaxy of Milky Way, according to scientists. "We are still not clear about the interior of pulsars," Zhang Shuangnan, lead scientist of HXMT and director of the Key Laboratory of Particle Astrophysics of the Chinese Academy of Sciences, said on Saturday.
"Current physical laws cannot describe well the substances in the state of a pulsar, since no lab on Earth can create a density as high as a pulsar. So we have to conduct more observations of pulsars," Zhang says. Lu Fangjun, chief designer of the payload of HXMT, says long-time monitoring of pulsars could help unravel the mystery of their energy sources.
A pulsar is so strange that when the first one was discovered, it was mistaken for signals from aliens. There are still many mysteries about this kind of star. It is found to be a highly magnetised, rotating neutron star, which emits two beams of electromagnetic radiation. This radiation can be observed only when the beam of emission is pointing towards the earth. It is much the same as how a lighthouse can be seen only when the light is pointed at an observer.
A neutron star is the collapsed core of a large star. Neutron stars are the smallest and densest stars known to exist. Though they typically have a radius of 10 km, they can have a mass about twice that of the Sun. A neutron star is so dense that one teaspoon of its material would have the mass of a mountain over 3,000 metres high, or about 900 times the mass of the Great Pyramid of Giza.
British astronomers Jocelyn Bell Burnell and Antony Hewish discovered the first pulsar in 1967. They nicknamed the strange signal LGM-1, for "little green men". It was not until a second pulsating source was found in a different part of the sky that the "LGM hypothesis" was abandoned. Scientists have discovered over 2,000 pulsars so far. The Milky Way is thought to have around 100 million of them, a figure obtained by estimating the number of stars that have undergone supernova explosions.
With their super strong gravitational and electromagnetic fields and high density, pulsars are regarded as natural laboratories of extreme physical conditions. | <urn:uuid:cf5c1eb6-3e47-49dd-af20-f0a19679df8f> | 2.96875 | 481 | News Article | Science & Tech. | 51.248654 | 95,501,008 |
We propose a technique based on a transmission grating placed in front of an imaging system (e.g. a telescope) mounted on a frame that can be rotated around the optical axis. The grating creates, for each point of the source image (e.g. a star), at the focal plane, an image composed by the undistorted image of the star plus symmetrical dispersion images of several diffraction orders. The grating is rotated and several images are captured for different angular positions of the same. By analyzing the different images obtained for a different grating angle, it is possible to build the hyperspectral cube. The advantages of this method is its simplicity, extreme compactness and low cost making it suitable both for amateur astronomy and low budget science laboratory. We will present preliminary experimental results along with a discussion about the achievable spectral and spatial resolution and photon collection efficiency as a function of different type of gratings and of the number of the captured pictures. Furthermore, we present the result when the method is applied to extended non-punctiform light sources.
Marco Pisani and Massimo Zucco, "Simple and cheap hyperspectral imaging for astronomy (and more)," Proc. SPIE 10677, Unconventional Optical Imaging, 1067706 (Presented at SPIE Photonics Europe: April 22, 2018; Published: 24 May 2018); https://doi.org/10.1117/12.2309835.
Conference Presentations are recordings of oral presentations given at SPIE conferences and published as part of the conference proceedings. They include the speaker's narration along with a video recording of the presentation slides and animations. Many conference presentations also include full-text papers. Search and browse our growing collection of more than 12,000 conference presentations, including many plenary and keynote presentations. | <urn:uuid:8ac3c672-d959-4d78-a083-b84ad720241d> | 3.15625 | 371 | Academic Writing | Science & Tech. | 33.052282 | 95,501,022 |
with the three dots representing the bond. R–X is the XB donor, and X is a halogen atom covalently bound to the R group and having an electrophilic region, or a potentially electrophilic region, on its electrostatic potential surface. It may happen that X is covalently bound to more than one group. In such cases the halogen may also form more than one halogen bond ( Figure Figure6 6 ). Y is the XB acceptor (donor of electron density) and can be an anion or a neutral species possessing at least one nucleophilic region, ., a lone-pair-possessing atom or π-system. This IUPAC definition has been framed as simply and comprehensively as possible to account for all the cases wherein there is evidence of bond formation involving a nucleophile and a positive region on a halogen atom X from a molecule or molecular fragment R–X. | <urn:uuid:2d4a76d3-814a-4f19-b555-22e41b1509f4> | 3.03125 | 194 | Documentation | Science & Tech. | 42.540342 | 95,501,026 |
Authors: Michael A. Sherbon
From the exponential function of Euler's equation to the geometry of a fundamental form, a calculation of the fine-structure constant and its relationship to the proton-electron mass ratio is given. Equations are found for the fundamental constants of the four forces of nature: electromagnetism, the weak force, the strong force and the force of gravitation. Symmetry principles are then associated with traditional physical measures.
Comments: 7 Pages. International Journal of Physical Research, 5, 2, 46-48 (2017). CC 3.0
[v1] 2017-09-27 11:22:06
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Vixra.org is a pre-print repository rather than a journal. Articles hosted may not yet have been verified by peer-review and should be treated as preliminary. In particular, anything that appears to include financial or legal advice or proposed medical treatments should be treated with due caution. Vixra.org will not be responsible for any consequences of actions that result from any form of use of any documents on this website.
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Wave Mechanics and Radioactive Disintegration
After the exponential law in radioactive decay had been discovered in 1902, it soon became clear that the time of disintegration of an atom was independent of the previous history of the atom and depended solely on chance. Since a nuclear particle must be held in the nucleus by an attractive field, we must, in order to explain its ejection, arrange for a spontaneous change from an attractive to a repulsive field. It has hitherto been necessary to postulate some special arbitrary ‘instability’ of the nucleus; but in the following note it is pointed out that disintegration is a natural consequence of the laws of quantum mechanics without any special hypothesis.
KeywordsRadioactive Decay Potential Energy Curve Potential Curve Wave Mechanics Spontaneous Change
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At a basic level, our nervous system is like a collection of wires that transmit electrical signals encoding our thoughts, feelings, and actions, both conscious and unconscious. The connections in our brain are formed by neurons that extend to each other and to muscles long wires called axons. Just as an electrical wire needs insulation, our axons require an insulating sheath (myelin) that helps to propagate the electrical signal and maximize the efficiency and velocity of these signals in our brain and body.
It is this property (myelination) that facilitates the long-distance communication in our nervous system across junctions called synapses, such that a thought can result in the movement of a finger or a toe. Diseases and injury that compromise the integrity of myelin such as multiple sclerosis, or peripheral neuropathies, have dramatic consequences like paralysis, uncoordinated movements, and neuropathic pain. The discovery reported in this study sheds light on the mechanisms that control how myelin is formed during development of the nerves. The article, which will be published in the November 3rd issue of Science, constitutes an important step forward in our understanding of the process of myelination, and opens the way to new research in this field.
More specifically, the study showed that a protein called Par-3 is at the base of the myelination process. This protein becomes localized to one side of the myelin-forming cells called Schwann cell, upon contact with the axon that is to be myelinated. Par-3 acts as a sort of molecular scaffold to set-up an "organizing centre", which brings together key proteins essential for myelination, in particular a receptor for a molecule secreted by the neurons. The scientists found that when they disrupted this organizing centre, cells could not form myelin normally. Importantly, their discovery demonstrates that Schwann cells need to become polarized so that they know which side of the cell is in contact with the axon so that they can initiate wrapping and bring essential molecules to this critical interface. These studies open the way to new research, which should help to identify other components that are recruited at the organizing centre set-up by Par-3. Importantly, in conditions such as multiple sclerosis or after injury, it is believed that Schwann cells could be used to re-myelinate axons. But so far this approach has proved to be relatively inefficient. Therefore, these experiments bring about the possibility that manipulating the Par-3 pathway in Schwann cells might allow for more efficient re-myelination of damaged or diseased nerves.
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
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This book was published following the 17th Annual Short Course of the Paleontological Society Held at the 106th Annual Meeting of the Geological Society of Amer Sunday, October 23,1994, Seattle, Washington.
This short course focuses on the highlights of vertebrate evolution, particularly the origin of the major vertebrate classes and their subsequent diversification. Since there have been previous short courses on dinosaurs and mammals, most of this program emphasizes the origin of vertebrates, plus fishes, amphibians, birds, and other topics not previously covered. However, our understanding of fossil mammals has changed greatly in the ten years since the 1984 short course, so three talks on important new developments in synapsid and mammalian palaeontology have been included. Clearly, not every topic in vertebrate paleontology can be covered in only twelve talks, but the editors feel that most of the critical new ideas are represented.
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Proving that necessity is indeed the mother of invention, the US states that feed water into the Chesapeake Bay — an expanse of water twice the size of Ireland — have begun to explore the use of market-based mechanisms to protect one of the world's largest watersheds. The Ecosystem Marketplace takes a look at how nutrient trading is being explored in Virginia and Pennsylvania. Midway through a ten-year push to rescue the polluted Chesapeake Bay and with little to show for it, government officials recently agreed to give market forces a shot at assisting with the cleanup: Water-quality credits will soon be up for sale in Virginia and Pennsylvania looks set to pay farmers to reduce the amount of pollution reaching its waterways. After noting the success other market-based conservation programs have had in cost-effectively reducing pollutants in smaller waterways (as well as lead and sulfur dioxide in the air), officials began agitating years ago to establish a major water quality trading program along the Chesapeake Bay. Now, with significant pollution still pouring into the Bay and the 2011 deadline staring them down, the state of Virginia finally passed legislation to create a water quality trading program in March, 2005. "This is a substantial piece of legislation," says Roy Hoagland, an executive with the Chesapeake Bay Foundation, a watchdog organization overseeing the cleanup of this 64,000-square-mile watershed, the largest in the world. "It will be a real test to see how viable trading will be in our goals to reduce pollution."
A Troubled Bay
Once famed for its pristine expanse, the Chesapeake Bay became so polluted by runoff from sewers, farms and factories in recent decades that fish could not survive in nearly half its waters. Seeking to address this crisis, President Ronald Reagan committed the nation to restoring the Bay in 1984. But the largely volunteer effort he triggered succeeded only in slowing the Bay's decline since agreements carried no penalty when ignored. Worried, and increasingly fed up with the pace of voluntary action, environmentalists eventually convinced courts to oversee a mandatory cleanup plan. Called Chesapeake 2000, the plan spelled out restoration goals for 2011, including the return of fish and other aquatic life, the clearing of murky waters and the dramatic reduction of measurable pollutants — specifically phosphorus and nitrogen. Reaching these goals, however, has proved cumbersome, partly because of the watershed's size and partly because it involves so many parties. In the Chesapeake, seven big political bodies — Virginia, Maryland, Delaware, Pennsylvania, West Virginia, New York and the District of Columbia — share a watershed twice the size of Ireland. With so many interests involved, change has taken time. After five years of planning, the states have finally drafted water quality standards to quantify the hoped-for success of their future efforts. Meanwhile, the Bay has continued dying as the number of people living within the watershed continues to grow. The region's population skyrocketed by 28 percent from 1979 to 1997, fueling more toilet flushes, larger manure-leaching farms, and new expanses of fertilized lawns. This all forms a toxic cocktail of phosphorus and nitrogen that inevitably finds its way downhill into the Bay. Ironically, algae, unlike most aquatic life, thrive on this nutrient mix and significantly complicate the problem. When algae's vast quantity of blooms die, they fall to the Bay's floor, promoting the growth of bacteria that consume the water's oxygen, literally suffocating the Bay. More than a third of the Chesapeake was ranked a "dead zone" last summer by the Chesapeake Bay Foundation. The water was so starved for oxygen that neither fish nor seafloor grasses could survive. The striped bass population, celebrated as recovered in 1995, dropped again last year by 20 percent. Underwater grasses continued disappearing. Overall, on a scale of A through F, the Bay scored a "D", according to the report card the Foundation released. "We've stemmed the tide of degradation but haven't turned the corner of restoration," explains the Foundation's Hoagland. "Let's put it this way:" he adds, "We're out of intensive care but certainly still in the hospital."
Enter Water Quality Trading
Faced with growing pressure and growing problems, some of the people interested in the health of the Chesapeake have begun to look at trading and market-based mechanisms to restore the Bay's health. Water-quality trading is akin to emissions trading, in that it sets limits (caps) on the amounts of pollution that enters a waterway, and then lets emitters trade amongst themselves to meet these limits. Advocates argue that the system enables small wastewater treatment plants to buy credits from larger sewage dischargers, who sometimes find it easier to limit their emissions. This, they say, allows smaller plants to meet their state permit limits for phosphorus and nitrogen discharges rather than undergoing extensive upgrades. Since such upgrades are typically paid for with public funds that yield minor improvements in water quality, proponents of trading schemes argue that they encourage scarce resources to be applied to upgrades that will make the biggest environmental improvements. "Nutrient trading," writes Paul Faeth, director of the Economics Program at the World Resources Institute, "is more politically acceptable than nutrient taxes, more effective than education and exhortation, and less costly and more sparing of public funds." Economists, like Faeth, have long encouraged states to implement nutrient trading to reduce pollution. In fact, Chesapeake Bay program partners — Virginia, Maryland, Pennsylvania, D.C., the Chesapeake Bay Commission and the federal government — signed a compact endorsing nutrient trading in March 2001. Yet the nutrient trading program signed into law in Virginia represents the first and only statutory framework for trading nutrient loads in the Chesapeake Bay watershed at a state level (small, more localized pilot projects exist in places like Pennsylvania). The law will go into effect on July 1 and trades are expected to begin in January, according to John Kennedy, a program manager within the Virginia Department of Environmental Quality who is helping develop the market. The units of exchange in these trades are cash dollars for pounds of nitrogen and pounds of phosphorus. The value of a pound will be set by the market, but Kennedy says it will likely be related to what it would have cost the plant to install upgraded pollution-ridding equipment. As with most cap-and-trade schemes, the Virginia nutrient trading program will focus on large emitters of pollutants — the so-called "point sources" — rather than the smaller polluters. For this reason, the initial — and majority — of trades are likely to involve wastewater treatment plants and other "point sources" trading amongst each other; sources whose discharges are easy to measure.
Good but not good enough
Nutrient trades between wastewater treatment facilities by themselves, however, will not dramatically lower the nitrogen and phosphorus entering the Bay. In Virginia, for instance, only 33 percent of the nitrogen in the Bay and 24 percent of the Bay's phosphorus comes from treatment plants and other "point sources". The rest of the pollution — in fact the majority of the Bay's nutrients — come from non-point sources such as residential lawns and farms in the form of manure, pesticides, and fertilizers that runoff into rivers and streams. For this reason, the Virginia legislation also provides for trading between point and non-point sources. Some treatment plants have begun experimenting with this option. For example, a technologically advanced plant being built in Loudoun County, Virginia, is investigating the possibility of purchasing and retiring active agricultural land, then turning it back into a forest buffer. For every two pounds of phosphorus or nitrogen that would no longer enter the Bay from the former farmland, the plant could likely expand its pollution limit by one pound, explains Kennedy. Virginia's nutrient trading program is also poised to embrace trading outside its borders. The program already allows for trading with the Blue Plains Wastewater Treatment Plant located in the District of Columbia. The largest plant in the entire watershed, Blue Plains serves populations from D.C., North Virginia and Maryland. "We have a shared resource and a shared responsibility for restoring it," says Kennedy.
Bidding for the Bay
Virginia is not alone in looking for market-based answers to the Chesapeake's environmental problems. Recently, Pennsylvania, which already has a pilot water-quality-trading program along the Conestoga River, announced that it will team up with the United States Department of Agriculture and the financial broker NatSource to run a "reverse auction" aimed at reducing the pollutants that leach into the Bay from farms. The auction, which will give out a total of US $90,000, is designed to get the most bang for each conservation buck. Unlike traditional auctions where buyers bid prices up, farmers will compete against each other to submit plans to reduce the greatest percentages of phosphorus runoff from their farms at the least cost. Those with the lowest bids will be awarded funding. They can choose from a variety of already-established best management practices, such as planting seeds directly into untilled soil to minimize runoff, or adding stream-bank fencing to restrict livestock from wading in the water. A new online tool created by the World Resources Institute will estimate phosphorus-runoff reductions and sort bids. Called NutrientNet, it may be used in the future to link point and non-point nutrient traders. "Everyone is facing the same challenge (of reducing nutrients in the Bay) that we arrive at in different ways," says Scott Van de Mark, spokesperson for the Pennsylvania Environmental Council, an environmental organization that designed and will help administer the auction. "The auction, like trading, is one tool in the tool box."
According to experts, the issue of reducing pollution from the "non-point sources", from farms and residential lawns, is likely to be one of the most important in determining the long-term health of the Bay. They say that saving the Bay will require money and political will targeted particularly at land use practices and at non-point sources of pollutants. "How many people on your street think when they fertilize their lawn they're contributing to the problem?" asks Suzie Greenhalgh, an economist for the environmental think tank World Resources Institute. It is precisely "because the problem involves all of us," she adds, that "it's not easy to regulate." Cleaning the Bay, nonetheless, has turned the corner, moving from a one-size-fits-all-enforcement approach to a market-based-incentive program that proponents expect will prove cost effective and reliable. "You've got to have some pretty inventive thinking because traditional thought is not getting us where we want to go," observes Kennedy. Given the size, the difficulties, and the complexities of the Chesapeake, it is likely that other creative strategies –beyond Virginia's water quality trading and beyond Pennsylvania's reverse auction—will be needed if the 2011 targets are going to be met. Rejuvenating the Bay will rely on the full toolbox of tools, including active enforcement of the federal Clean Water Act and taxpayer subsidies to help cover the cleanup's cost. "It's possible to get all the goals we want accomplished by 2011," says Hoagland of the Chesapeake Bay Foundation. "The question is whether the political will is there to make it happen. We still have a high mountain to climb." Alice Kenny is a prize-winning science writer and a regular contributor to The New York Times Westchester Section. She can be reached at firstname.lastname@example.org. | <urn:uuid:5d33eedf-44c9-4629-b5c2-a0b4509721e6> | 3.390625 | 2,319 | News Article | Science & Tech. | 34.349498 | 95,501,082 |
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What is Normality ?
Normality is the ratio of gram equivalent weight to volume of solution in liter.
where gram equivalent is the measure of reactive capacity of molecule consider for normality.
Normality (N) :-
Gram equivalent weight / Volume of the solution in liter.
Unit => N = "eq/L" (equivalent per liter)
Aufbau PrincipleAccording to this principle in the ground state of the atoms the orbital’s are filled in order of their increasing energies means electrons enter higher energy orbital’s so order in which orbital’s are filled is 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p.
Pauli Exclusion Principle
· given by W. Pauli (1926).
· Two electrons in an atoms can’t have same set of 4-quantum no.
· Only two electrons may exist in same orbital and these electrons must have opposite spin.
Hund’s Rule of Maximum Multiplicity
· According to this rule pairing of electron in the orbital’s belonging to the same sub-shell (p, d or f)· Does not take place until each orbital belonging to that sub-shell has got one electron each i.e. it is singly occupied.
Definition of Nuclear Chemistry- Nuclear chemistry is the branch of chemistry, which deals with the study of changes in the nucleus of an atom, radioactivity and nuclear reactions.
What is Nuclear Chemistry?
Nuclear chemistry is interesting field of chemistry in which we learn how nuclear reactions happens and how different types of changes occurs in nucleus of an atom also we learn about radioactivity and radioactive elements.
Founder of Nuclear Chemistry
Marie Curie was the founder of the nuclear chemistry.
Marie Curie was a physicist and chemist who lead revolutionary research on radioactivity and she won Nobel Prize in the field of radioactivity
What is radioactive substances?Substances which emits radiation by there self are known as radioactive substances.
What is radioactivity?Phenomenon of radioactive substances to emits radiations is known as radioactivity.
What is importance of radioactivity?Radioactive substances (or radioactive isotopes of elements) are useful in many physical and chemical reactions. Useful in determining complex reaction mechanism. Radioactivity have several applications in different fields of science like chemical science, medical science, agriculture fields, industrial fields etc.
What is Molality?It is the ratio of moles of substance to kilogram of solvent.
Where mole is weight in gram divided by molecular weight.
Molality is chemistry terminology.
Molality (m) :-No. of moles of the solute / Mass of solvent in Kilogram (Kg).
Unit => m = Moles/Kg
|What is Molality|
Branches of Chemistry
Chemistry is branch of Science, which is further divided into many branches like-
हिंदी माध्यम में रसायन विज्ञान नोट्स हिंदी में हमारे रसायन शास्त्र के नोट्स पाने के लिए नीचे दिखाए चरणों का पालन करें - अ - स...
11th & 12th Classes Formula in PDF Below is the list of Chemical Formulas Resources 1. Chemistry formulas for Atoms, Molecules and...
Solid State Solid: - Matter which posses rigidity having definite shape &volume is called solid. Types of solid:- ...
Atomic Theory of matter :- According to this theory , atom is the ultimate particle of m...
Classification of Elements Mendeleev periodic law :- Mendeleev explanation that properties ...
Surface Chemistry Adsorption: - The accumulation of molecular species at the surface rat...
ELECTROCHEMISTRY Electrolysis: It is the process of decomposition of an electrolyte by the passage of electricity...
States Of Matter · Water exists in three state i.e. solid (ice), liquid (portable water), gas (steam, vapors). · In thes...
Organic Chemistry What is Organic Chemistry ? Organic chemistry is a branch of chemistry which involve the scientific study of struct...
Chemistry of Elements of First Transition Series There are four types of orbital i.e. s, p, d and f. On the basis of electronic configu...
Chemistry Quiz contains different pages linked below containing chemistry quiz question...
1. Science Quiz Part11
2. Science Quiz Part12
3. Science Quiz Part13
4. Science Quiz Part14
5. Chemical Reactions Quiz Part15
6. Chemical Reaction Quiz Part16
7. Pharmaceutical Chemistry Quiz Part17
8. Acids and Bases Quiz Part18
9. Some Basic Concept of Chemistry MCQs
10. Structure of Atom MCQs | <urn:uuid:103d3433-2fea-40d5-9295-a0a4b264c4bd> | 3.515625 | 1,190 | Content Listing | Science & Tech. | 57.362927 | 95,501,091 |
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The Micropholcommatidae are a family of tiny, distinctive araneoid spiders, known from southern-temperate habitats throughout Australasia and Chile. The greatest abundance of individuals and the largest diversity of taxa occur in the cooltemperate rainforests of south-eastern Australia and New Zealand, where micropholcommatid spiders can be very common within moss and leaf litter microhabitats. Although poorly studied biologically and largely neglected taxonomically, the Micropholcommatidae are a diverse lineage, with a significant--and previously unrecognised--generic diversity.
The monograph in this volume presents a complete generic-level revision of the spider family Micropholcommatidae. The phylogenetic position and internal phylogeny of the family are tested with two separate morphological cladistic analyses, the results of which inform a comprehensive generic-level classification. In total, 26 new species, 12 new genera, one new tribe and two new subfamilies are described, taking the total documented micropholcommatid fauna to 58 species. The distribution and Gondwanan biogeography of the family are also discussed, and natural history information is provided where known. Most importantly, the results of this paper present a taxonomic framework and a phylogenetic foundation for all future research on the Micropholcommatidae; a template by which new species can be described and existing species can be identified, and a valuable dataset for exploring phylogenetic hypotheses.
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London: NASA has revealed that scores of giant asteroids are on course to hurtle close to Earth before the end of February.
According to the researchers, some asteroids are more than 1km wide, the size of a double decker bus, and threaten devastating consequences if they were to strike our planet, the Daily Express reported.
Experts also warned that if one of these asteroids, some of which travel at up to 70,000 miles an hour, were to hit Earth it could "alter life as we know it" and plumes of debris thrown into the atmosphere would change the climate making the planet inhabitable for all life including humans and that an impact would still be catastrophic destroying cities and knocking out transport and communication networks.
According to NASA's Near Earth Object Programme, there are 68 'close approaches' forecast before the end of next month and the next, which is due on January 3, is the 490-metre wide 2005 YQ96 asteroid currently hurtling through space at more than 30,000 miles per hour.
The biggest to skim the planet will be the mile-wide 2007 EJ asteroid due to throttle past on January 12th at 34,500 miles per hour.
Experts said that although it is unlikely any of these will hit the Earth , there is always a chance they may veer off course or explode showering the planet with debris and an impact would trigger a disaster similar to the collision which killed the dinosaurs 65 million years ago. | <urn:uuid:0dcf2eaa-3456-4019-921a-1d58e7beb97c> | 2.859375 | 296 | News Article | Science & Tech. | 32.940714 | 95,501,121 |
New York, April 19 (IANS) Space missions are likely to encounter a growing threat of more debris, scientists warned on Tuesday at the 7th European Conference on Space Debris.
The four-day meeting was held in the southern German city of Darmstadt, where the European Space Operations Centre (ESOC) is located.
Since 1957, over 4,900 space launches have led to an on-orbit population of more than 18,000 tracked objects, Xinhua news agency reported.
Of those, only 1,100 are functional spacecraft and the remaining are space debris, according to European Space Agency (ESA), an intergovernmental organisation consisting of 22 European member states.
As regards tiny objects larger than one millimetre, which are hard to be tracked but able to harm spacecraft in a collision, the amount of those objects has risen to ca. 150 million.
In addition, around 20,000 orbiting fragments with sizes over 10 centimetres have been found nowadays, 12,000 more than the total amount in 1993.
“We are very much concerned,” said Rolf Densing, director of operations at the ESA.
In the coming days, experts will further discuss different aspects of space debris research including measurement techniques, environment modelling theories, risk analysis techniques, and protection designs. | <urn:uuid:37b47da2-77b5-498d-8fa3-5e482d55e103> | 3.4375 | 267 | News Article | Science & Tech. | 36.412047 | 95,501,130 |
Jaguar electric boat breaks the world’s speed record with its electric boat. As we know Jaguar is famous for its luxury vehicle brand of Jaguar Land Rover, and not only luxury vehicles but also electric cars, and what about electric boats? It really sounds fantastic, they released not only electric boat but also electric boat brakes the speed record.
The sound of space is truly strange. The sound of Earth! “It’s called chorus,” explains Craig Kletzing of the University of Iowa. “This is one of the clearest examples we’ve ever heard”. The Researcher explains the sound of Earth. “This is what the radiation belts would sound like to a human being if we had radio antennas for ears,” says Kletzing, whose team at the University of Iowa built the “EMFISIS” (Electric and Magnetic Field Instrument Suite and Integrated Science) receiver used to pick up the signals.View More Scientists Reveal the Sound of Space That Is Really Terrifying
Scientists received the evident certificate that growth of galaxy is limited at the expense of new stars. Supervision showed that new stars throw out gas streams which could go on a further increment of their quantity out of galaxy limits. The group of researchers of Germany, Canada and the USA used ALMA radio telescope for supervision. This tool is sensitive to a radio emission of submillimetric range. Studying the central part of a galaxy of NGC 253 scientists found some gas streams proceeding out of its limits. Thus the principle of supervision based on registration of radio waves, allowed to see only streams of the gas consisting of a monoxide of carbon that is carbon monoxide. The chemical composition of gas specifies that streams of substance are formed not at the expense of hot plasma of stars (it consists generally of hydrogen), and at the expense of the cold interstellar gas picked up by a star wind.View More Gas streams of stars stopped growth of galaxy
Astrophysics from the Southern European observatory (ESO) photographed a galaxy’s absorption of gas clouds surrounding it. The new data obtained with help of Very Large telescope (VLT) are remarkable that the galaxy is removed from Earth on distance more than ten billion light years. And respectively it is visible in that look in which was during an era of the young Universe. As at such distance the galaxy appears the smallest even at supervision through Very Large telescope (VLT), astronomers had to use indirect methods for an assessment of volume of absorption of gas and definition of details of process.View More Very Large Telescope captured galaxy absorption of gas
Scientists learned of what were constructed the first stars and galaxies of the Universe. Thanks to a radio telescope of CSIRO which is located in the Australian Observatory Parkes, astronomers could find the main construction material from which the first stars and galaxies of our Universe were created. BY the words of Professor Ron Ekers the telescope of CSIRO is one of the few telescopes in the world which could carry out such difficult work and find a material from which the first stars and the first galaxies in the Universe were created. It appeared that cold molecular hydrogen (H2) was the key material of forming the first stars and galaxies. It was found in early stars and galaxies with help of CO intermediary gas which radiates radio waves. To make the discovery, scientists studied the remote protogalaxies and other protoobjects of the Universe.View More Composition of the first stars and galaxies of the Universe
The international team of researchers created the video map of the movement of galaxies neighbor the Universe in more detail, than before. Video map is provides dynamic three-dimensional idea of the Universe with help of turn, scrolling and scaling. The space project Streams planned visible and dark matter density round our galaxy Milky Way at distance of 300 million light years. Our galaxy Milky Way lies in a congestion of 100000 galaxies. The movement of tectonic plates shows properties of an interior of Earth. And the movement of galaxies shows information on the main components of the Universe, which is dark energy and dark matter. Dark energy is the mysterious force, which causes expansion of the Universe.View More Video map of the movement of galaxies near Universe
In intergalactic space astronomers found huge threadlike clouds of gas from the ionized hydrogen, which can be the indicator of thin threads from the dark matter connecting cells of global space. The previous cycles of supervision over empty space between galaxies indicated of possibility existence of clouds of hydrogen between them. But the astronomers couldn’t determine the sizes of these hydrogen gas clouds and their property. With help of a radio telescope Green-Bank the astronomers were succeeded to understand that it not shapeless clouds, but quite accurate structures. For several weeks the astronomers watched the closest neighbors of our Milky Way, Andromeda’s galaxies and the Triangle. These “star megalopolises” drew attention of astronomers still a year ago, when they found in data of radio observations hints on existence of big congestions of hydrogen in intergalactic space. According to astrophysicists, all these clouds are located along the line connecting Andromeda and the Triangle.View More Astronomers found hydrogen gas clouds – the bridge between the galaxies
The American astronomers found rather small galaxy of HFLS3, stars in which were formed in two thousand times quicker, than in our Milky Way that allows ranking it as a new class of super-starburst galaxy in the early Universe. According to the astronomers, this galaxy is the certificate of that, that in the very ancient time, through only 800 million years after the Big Bang, there were possible rough episodes of a star formation. The scientists managed to track one of the most important eras in the history of development of the first galaxies of the Universe. The astronomers found HFLS3 starburst galaxy with super speed star formation, studying the data collected by a land radio telescope of VLA and orbital observatory Hershel during supervision over constellation of the Dragon. In these pictures scientists noticed rather bright point, which range was strongly stretched because of huge distance, which light passed from its source to observers on Earth.View More The astronomers found starburst galaxies In the Dragon constellation
Astrophysics learned to estimate quantity of an interstellar dust in galaxies on range of distribution of ultra-violet radiation from the ionized hydrogen. The study was done with information from Hubble telescope. During the research the scientists analyzed structure of 14 galaxies located in relative proximity from Earth. Astrophysics paid the main attention to distribution in radiation of a series of Lyman. This ultra-violet radiation results from hydrogen transition from unexcited condition.
Atom transition from the lowest in the basic leads conditions to photon radiation with a length of wave of 121,6 nanometers. This length of a wave is called an alpha as the hydrogen line. Its important property is that such radiation before leaving limits of a galaxy and to reach the Earth is repeatedly reradiated. As a result, round galaxies in a range of the alpha line it is often possible to observe gala, radiated by interstellar gas.
Astronomers from Observatory “Gemini” received the most detailed to date image of the unusual galaxy NGC 660, relating to a rare class of polar galaxies. The galaxy NGC 660 is located at a distance of 40 million light years from Earth near the constellation Pisces. It is as if two separate star clusters: the spiral and lenticular. Such galaxies are called polar – they rotate the outer ring over the poles of the internal cluster. In addition, NGC 660 is the only other known polar galaxies in which the center has an old lenticular congestion. All polar galaxies are a result of the interaction of two separate star clusters. Some of them can be formed by the collision of two galaxies formed (for example, a galaxy can be formed by a merger in the future, with the Milky Way Andromeda).View More Unusual Galaxy Photographed from Gemini Observatory | <urn:uuid:7e94bffd-adfd-4cb1-8854-0bc04f790100> | 2.828125 | 1,620 | Content Listing | Science & Tech. | 35.751932 | 95,501,156 |
Weather Control and Creation to Use as a Screen for Troop Advancement
Creating a Hurricane using a Space based laser array to heat up surface waters when conditions are right. By using a tropical storm system and super heating the water in the path and then in a counter clock wise direction if in the Northern Hemisphere or Clock-wise if in the Southern Hemisphere because;
"A hurricane is an immense circulating storm, an intense case of a class of weather systems called tropical cyclones. At the center of a cyclone is a region of extremely low atmospheric pressure. Because this region is at a lower pressure than its surroundings, winds blow from the high-pressure areas inward toward the central low. The coriolis force (which is due to the rotation of the Earth) causes these winds to be deflected to the side. So instead of the winds blowing straight toward the center of the hurricane, they begin to blow around it. This causes the hurricane to circulate. Hurricanes always rotate counter-clockwise in the northern hemisphere and clockwise in the southern hemisphere."
One of the easiest ways to heat the surface would be to use large UUV-Underwater Unmanned Vehicles which are twin-tubed shaped which would slowly unroll like a scroll and sink a few inches below the surface with a floating absorbing material which would heat up when hit with the laser. Thus super heat the waters surface. It could also be a Solar Powered skin made of:
"In Energy News. Super duper thin solar cells can be made with a thin sheet about 2-3 microns coated with Copper Indium Diselenide. What is that? Exactly what I thought but it is a thin material similar to glass. It reaches conversion percentages as much as 18% .
Energy is free. You can never be too free or too thin."
The UUV tubes would that of the Seahorse UUV only triple the length which would have the companion tube a giant roll containing the skin to be used and float between the two.
Now then as the eye of the Hurricane forms you put your robotic and human landing forces in the eye of the Hurricane and travel to the shore without detection and without conflict. Your landing force is secure thanks to a little help of the temporary modification of Mother Natures perfect patterns. No one can deny that a Hurricane is very disruptive and destructive event. You cannot defend a beach against an attack if you are fully disrupted by the strength of a Hurricane, Typhoon, very large Tropical Storm or big weather event. We know from our experience with Hurricanes each year that FEMA has a tough enough time cleaning up after the destruction, power outages and the like. We know as Hurricanes reach land and surface obstructions that winds slow and eventually the storm collapses, but there is also a way to deflate a storm after you no longer need it for your cover. We can also bring in behind the storm cool water along with logistics of the sixth fleet;
Interesting information on Hurricanes and how they form the force needed and the changes in surface temperatures needed and the conditions necessary for the natural creation of Hurricanes:
It appears that creating a Hurricane is quite possible with our modern technology, also meaning that watering the desert or creating rain is also to fill up aquifers, water reservoirs or even large lakes stricken by droughts. And there are a number of ways to defeat a Hurricane such a poly balls which can soak up 2000 times their weight in water or precipitation which could be dropped from a large cargo plane such as a C-141, C-5 or many of such aircraft flying above near the top of the storm.
In conclusion a Hurricane is the ultimate diversion and smoke screen to safely land your forces without having to deal with heavy losses of life such as the decision faced by Eisenhower who had to deal with as our troops that landed at Normandy to conquer evil.
"Lance Winslow" - If you have innovative thoughts and unique perspectives, come think with Lance; www.WorldThinkTank.net/wttbbs
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Here's the sexual harassment report that felled a famed geneticist—and his defense - Science Magazine
Para Trooper Gliders With Angle of Attack Motor or Crank
Para Trooper Gliders were very popular in WW II, they were used by both the Axis and Allied Forces. Some of these gliders were huge in size and the Germans had one which had took three bombers to get it off the ground along with two-four rockets used in take off.
4D Mapping of Mars Will Find Life
Let us discuss the mapping of Mars and some thoughts on the matter. We have mapped the Earth by using Satellites and have a complete GIS mapping with complete mineral deposits, underground oil areas, volcanic plumes and even huge natural water aquifers.
Mini-Robots, Motherships, Swarm Strategies, Wasps, Ants, Organization and Delivery
Robots are for every one. Tech TV now host Battle Bots which is a big hit with viewers and draws crowds as big as WFB Wrestling.
Precognition Shock to Prevent Bullet Strike
It is a pretty well known fact and has been proven that the body seems to pre-adjust to changes in advance of events by a second or two. For instance there have been studies of test subjects with finger sensors, which would show the subjects pulse or adrenaline spiked right before they were to be shocked.
Will Clones Run the World?
In the US it appears that we have decided that "life is not for sale" and that the cloning debate is over and our scientists are forbidden by law from attempting to clone humans. In other countries they are currently trying and will most likely continue to try until they get it right.
Electric Power Production From Magnetic Tapes
ATHENS - GREECE, -- An individual person called Basil Dimitropoulos, who is a graduate Electrical Engineer with specialization in Magnetic Recording Applications, has long announced that he developed a project that concerns Electric Power Production From Magnetic Tapes. This electromotive system affects directly the Global Home Appliances Industry and Transportation Industry, resulting in portable and mobile power supplies for Household Devices and Electric Vehicles.
UAV Air-Breathing SAM Upgrade Recommendations
Can a hybrid Surface to Air Missile, UAV loiter for hours and then become a missile to down an enemy aircraft?Small UAV surface to air missile (SAM), which is air-breathing is a good idea and yields many possibilities to the future of air combat.http://www.
What are the Biggest Solar Projects?
Solar power will be necessary for space exploration and off planet colonies on the moon and Mars in the next few decades and our advances here on Earth will assist us with the knowledge we need to power them up. Some may not realize but we have come a long way in our solar technology in the last few decades and we are now ready to take this experience and knowledge to the next level; to build something out of this world.
Life on Mars, Warm Water Under our Ice Caps, Evidence, Microbes under Our Feet
Well many people out there are asking is there really life on Mars? Our Thinking Group has been asking not if, what type?An article I remember reading and article in Astronomy Magazine back in 1996 that read was there life on Mars and it was an article about a meteorite that landed here on Earth and it was found in 1984 in Antarctica in the Allen Hills ice fields, like I even know where that is? It had bacteria fossils and remains of bacteria that lived about 3.6 billion years ago and the meteor appeared to have come from Mars.
An Immortal Horse
Egyptian scholars know there is little other than fiction that can be written about the civilization that lived on the banks of the Nile in far more recent times than the beginning of the 'Old Copper Culture'. All these things are related and the old fictions are replaceable with the story of a worldwide culture with trading posts in each and every part of the world.
Spray on Dirt for Camouflage
Super sticky spray on dirt or mud simulation coating or wash-off-able paint is needed to protect our troops in combat. It can be used for aircraft bottoms, helicopters and humvees.
Making Diamonds Using The Earth
We can make diamonds using the Earth's inner forces, extreme pressure and heat. We simply send Carbon Blocks in tubes, which have been drilled into the Earth's Mantle.
The Joy of Recycling
I have always been an advocate of recycling. Even though I am not always convinced of its financial viability, I am thoroughly convinced of its value as a means of increasing public awareness of the cost of our consumerism.
Aliens in Archaeology
As you read this book you will have to suspend the disbelief you feel when confronted with my assertions that for at least 5000 years man has been in close contact all over the world. If you have read my other books you will know I have made the case better than any and that there are lots of good scholars who agree with me.
Three Types of Telescopes - What are the Advantages
Refractors, Newtonian reflectors and Catadioptrics are the three main types of telescopes. All these different types have the same purpose, but each telescope design does it differently.
Einstein Half Dead
100 years ago Albert Einstein developed his Relativity Theory of physics that claimed that the universe is actually based on a space-time-gravity continuum (a non-mechanical version of Rene Descartes' earlier mechanical ether theory) and with time as variable and relative.Einstein believed that his theory disproved "all of Isaac Newton's physics theory", and that "Newton's theory" had disproved all earlier physics theories.
Saving People in Disaster Crisis, Concept
So often when we see huge Natural Disasters there are many people killed, but for everyone who perishes there are 5-10 people injured; many very seriously. So often too the region of the world were the disaster occurs does not have enough hospital beds, medical professionals or the right equipment needed to help save those lives.
Cloaking a UAV in Flight
If you will recall the Klingon Space Craft and Warship cloaked it's self as it attacked the USS Enterprise under Captain James T. Kirk.
Mississippi River Mouth Debris Jetting Using Acoustic Transducers
The Mighty Mississippi is backing up and causing flooding issues due to over growth build up at its river mouth. This is dangerous because that region is already so close to sea level.
How Do Cities Grow?
You see the cities in America started where there was a river and small populations sprung up, then the railroad steam engines needed a place to fill up the water. Eventually the towns got larger and grew near the rail stations.
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Please use this identifier to cite or link to this item:
|Title:||Whole-cell imaging at nanometer resolutions using fast and slow focused helium ions|
|Citation:||Chen, X., Udalagama, C.N.B., Chen, C.-B., Bettiol, A.A., Pickard, D.S., Venkatesan, T., Watt, F. (2011-10-05). Whole-cell imaging at nanometer resolutions using fast and slow focused helium ions. Biophysical Journal 101 (7) : 1788-1793. ScholarBank@NUS Repository. https://doi.org/10.1016/j.bpj.2011.08.028|
|Abstract:||Observations of the interior structure of cells and subcellular organelles are important steps in unraveling organelle functions. Microscopy using helium ions can play a major role in both surface and subcellular imaging because it can provide subnanometer resolutions at the cell surface for slow helium ions, and fast helium ions can penetrate cells without a significant loss of resolution. Slow (e.g., 10-50 keV) helium ion beams can now be focused to subnanometer dimensions (∼0.25 nm), and keV helium ion microscopy can be used to image the surfaces of cells at high resolutions. Because of the ease of neutralizing the sample charge using a flood electron beam, surface charging effects are minimal and therefore cell surfaces can be imaged without the need for a conducting metallic coating. Fast (MeV) helium ions maintain a straight path as they pass through a cell. Along the ion trajectory, the helium ion undergoes multiple electron collisions, and for each collision a small amount of energy is lost to the scattered electron. By measuring the total energy loss of each MeV helium ion as it passes through the cell, we can construct an energy-loss image that is representative of the mass distribution of the cell. This work paves the way to use ions for whole-cell investigations at nanometer resolutions through structural, elemental (via nuclear elastic backscattering), and fluorescence (via ion induced fluorescence) imaging. © 2011 Biophysical Society.|
|Source Title:||Biophysical Journal|
|Appears in Collections:||Staff Publications|
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where π is the prime-counting function and li is the logarithmic integral function. These bounds have since been improved by others: there is a crossing near . It is not known whether it is the smallest.
John Edensor Littlewood, who was Skewes's research supervisor, had proved in Littlewood (1914) that there is such a number (and so, a first such number); and indeed found that the sign of the difference π(x) − li(x) changes infinitely often. All numerical evidence then available seemed to suggest that π(x) was always less than li(x). Littlewood's proof did not, however, exhibit a concrete such number x.
In Skewes (1955), without assuming the Riemann hypothesis, Skewes proved that there must exist a value of x below
Skewes's task was to make Littlewood's existence proof effective: exhibiting some concrete upper bound for the first sign change. According to Georg Kreisel, this was at the time not considered obvious even in principle.
More recent estimates
These upper bounds have since been reduced considerably by using large scale computer calculations of zeros of the Riemann zeta function. The first estimate for the actual value of a crossover point was given by Lehman (1966), who showed that somewhere between 1.53×101165 and 1.65×101165 there are more than 10500 consecutive integers x with π(x) > li(x). Without assuming the Riemann hypothesis, H. J. J. te Riele (1987) proved an upper bound of 7×10370. A better estimation was 1.39822×10316 discovered by Bays & Hudson (2000), who showed there are at least 10153 consecutive integers somewhere near this value where π(x) > li(x), and suggested that there are probably at least 10311. Bays and Hudson found a few much smaller values of x where π(x) gets close to li(x); the possibility that there are crossover points near these values does not seem to have been definitely ruled out yet, though computer calculations suggest they are unlikely to exist. Chao & Plymen (2010) gave a small improvement and correction to the result of Bays and Hudson. Saouter & Demichel (2010) found a smaller interval for a crossing, which was slightly improved by Zegowitz (2010). The same source shows that there exists a number x violating π(x) < li(x) below . This can be reduced to , assuming the Riemann hypothesis. Stoll & Demichel (2011) gave .
|Year||near x||# of complex
|2000||1.39822×10316||1×106||Bays and Hudson|
|2010||1.39801×10316||1×107||Chao and Plymen|
|2010||1.397166×10316||2.2×107||Saouter and Demichel|
|2011||1.397162×10316||2.0×1011||Stoll and Demichel|
Rigorously, Rosser & Schoenfeld (1962) proved that there are no crossover points below x = 108, improved by Brent (1975) to 8×1010, by Kotnik (2008) to 1014, by Platt & Trudgian (2014) to 1.39×1017, and by Büthe (2015) to 1019.
There is no explicit value x known for certain to have the property π(x) > li(x), though computer calculations suggest some explicit numbers that are quite likely to satisfy this.
Even though the natural density of the positive integers for which π(x) > li(x) does not exist, Wintner (1941) showed that the logarithmic density of these positive integers does exist and is positive. Rubinstein & Sarnak (1994) showed that this proportion is about 0.00000026, which is surprisingly large given how far one has to go to find the first example.
Riemann gave an explicit formula for π(x), whose leading terms are (ignoring some subtle convergence questions)
where the sum is over zeros ρ of the Riemann zeta function. The largest error term in the approximation π(x) = li(x) (if the Riemann hypothesis is true) is li(√)/2, showing that li(x) is usually larger than π(x). The other terms above are somewhat smaller, and moreover tend to have different complex arguments so mostly cancel out. Occasionally however, many of the larger ones might happen to have roughly the same complex argument, in which case they will reinforce each other instead of cancelling and will overwhelm the term li(√)/2.
The reason why the Skewes number is so large is that these smaller terms are quite a lot smaller than the leading error term, mainly because the first complex zero of the zeta function has quite a large imaginary part, so a large number (several hundred) of them need to have roughly the same argument in order to overwhelm the dominant term. The chance of N random complex numbers having roughly the same argument is about 1 in 2N. This explains why π(x) is sometimes larger than li(x), and also why it is rare for this to happen. It also shows why finding places where this happens depends on large scale calculations of millions of high precision zeros of the Riemann zeta function. The argument above is not a proof, as it assumes the zeros of the Riemann zeta function are random which is not true. Roughly speaking, Littlewood's proof consists of Dirichlet's approximation theorem to show that sometimes many terms have about the same argument.
In the event that the Riemann hypothesis is false, the argument is much simpler, essentially because the terms li(xρ) for zeros violating the Riemann hypothesis (with real part greater than 1/2) are eventually larger than li(x1/2).
The reason for the term is that, roughly speaking, counts not primes, but powers of primes weighted by , and is a sort of correction term coming from squares of primes.
- Bays, C.; Hudson, R. H. (2000), "A new bound for the smallest with " (PDF), Mathematics of Computation, 69 (231): 1285–1296, doi:10.1090/S0025-5718-99-01104-7, MR 1752093, Zbl 1042.11001
- Brent, R. P. (1975), "Irregularities in the distribution of primes and twin primes", Mathematics of Computation, 29 (129): 43–56, doi:10.2307/2005460, JSTOR 2005460, MR 0369287, Zbl 0295.10002
- Büthe, Jan (2015), An analytic method for bounding , arXiv: , Bibcode:2015arXiv151102032B
- Chao, Kuok Fai; Plymen, Roger (2010), "A new bound for the smallest with ", International Journal of Number Theory, 6 (03): 681–690, arXiv: , doi:10.1142/S1793042110003125, MR 2652902, Zbl 1215.11084
- Kotnik, T. (2008), "The prime-counting function and its analytic approximations", Advances in Computational Mathematics, 29 (1): 55–70, doi:10.1007/s10444-007-9039-2, MR 2420864, Zbl 1149.11004
- Lehman, R. Sherman (1966), "On the difference ", Acta Arithmetica, 11: 397–410, doi:10.4064/aa-11-4-397-410, MR 0202686, Zbl 0151.04101
- Littlewood, J. E. (1914), "Sur la distribution des nombres premiers", Comptes Rendus, 158: 1869–1872, JFM 45.0305.01
- Platt, D. J.; Trudgian, T. S. (2014), On the first sign change of , arXiv: , Bibcode:2014arXiv1407.1914P
- te Riele, H. J. J. (1987), "On the sign of the difference ", Mathematics of Computation, 48 (177): 323–328, doi:10.1090/s0025-5718-1987-0866118-6, JSTOR 2007893, MR 0866118
- Rosser, J. B.; Schoenfeld, L. (1962), "Approximate formulas for some functions of prime numbers", Illinois Journal of Mathematics, 6: 64–94, MR 0137689
- Saouter, Yannick; Demichel, Patrick (2010), "A sharp region where is positive", Mathematics of Computation, 79 (272): 2395–2405, doi:10.1090/S0025-5718-10-02351-3, MR 2684372
- Rubinstein, M.; Sarnak, P. (1994), "Chebyshev's bias", Experimental Mathematics, 3 (3): 173–197, doi:10.1080/10586458.1994.10504289, MR 1329368
- Skewes, S. (1933), "On the difference ", Journal of the London Mathematical Society, 8: 277–283, doi:10.1112/jlms/s1-8.4.277, JFM 59.0370.02, Zbl 0007.34003
- Skewes, S. (1955), "On the difference (II)", Proceedings of the London Mathematical Society, 5: 48–70, doi:10.1112/plms/s3-5.1.48, MR 0067145
- Stoll, Douglas; Demichel, Patrick (2011), "The impact of complex zeros on for ", Mathematics of Computation, 80 (276): 2381–2394, doi:10.1090/S0025-5718-2011-02477-4, MR 2813366
- Wintner, A. (1941), "On the distribution function of the remainder term of the prime number theorem", American Journal of Mathematics, 63 (2): 233–248, doi:10.2307/2371519, JSTOR 2371519, MR 0004255
- Zegowitz, Stefanie (2010), On the positive region of , Master's thesis, Manchester Institute for Mathematical Sciences, School of Mathematics, University of Manchester
- Demichels, Patrick. "The prime counting function and related subjects" (PDF). Demichel. Archived from the original (pdf) on Sep 8, 2006. Retrieved 2009-09-29.
- Asimov, I. (1976). "Skewered!". Of Matters Great and Small. New York: Ace Books. ISBN 978-0441610723. | <urn:uuid:a01608e5-0f07-45cb-bc66-0c537a9ea856> | 2.703125 | 2,392 | Knowledge Article | Science & Tech. | 80.520003 | 95,501,203 |
Biophysicists at Stanford University have finally answered one of the most fundamental questions in molecular biology: How does the tiny motor molecule, known as kinesin, move across a living cell? According to the researchers, the solution to this longstanding problem will provide new insight into how motor proteins function, and may open new avenues of investigation for the treatment of cancer and various neurodegenerative diseases, such as Alzheimers and Huntingtons.
The study, published in the Dec. 4 online edition of the journal Science, was co-authored by Steven M. Block, a professor of applied physics and of biological sciences at Stanford.
"Motion at the cellular level is a hallmark of being alive," Block said. "A fundamental question is, how did living organisms figure out how to move? The answer is they developed kinesin and several other very efficient protein motors. If kinesin were to fail altogether, you wouldnt even make it to the embryo stage, because your cells wouldnt survive. Its that important."
Mark Shwartz | EurekAlert!
O2 stable hydrogenases for applications
23.07.2018 | Max-Planck-Institut für Chemische Energiekonversion
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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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23.07.2018 | Health and Medicine | <urn:uuid:f70c0fa9-0a5e-4f83-9f07-2315cbd1830d> | 3.5 | 803 | Content Listing | Science & Tech. | 37.016049 | 95,501,208 |
Heated Debate Surrounds Galaxy Seeming to Lack Dark MatterApril 16, 2018
Strong skepticism should always accompany strong claims. One such recent claim has generated a ton of talk about a strange, fuzzy galaxy that appears to be missing its dark matter.
That a galaxy would have no dark matter is an amazing finding, and it was covered rather uncritically by lots of news outlets (including us!). Since then, some scientists have taken to social media and the arXiv science paper server to discuss the scant data used to make the surprising conclusion.
“The idea we were seeing a strong signature of a dark matter-free system seems incorrect,” Michelle Collins, astronomy lecturer at the University of Surrey in the United Kingdom, told Gizmodo.
Last month, the prestigious science journal Nature published a striking observation from a team of astronomers with a title akin to astronomy clickbait: “A galaxy lacking dark matter.” Using their telescope, the Dragonfly Telephoto Array, they spotted a dim galaxy shaped like a fuzzy and roughly the same width as the Milky Way. They observed the speed of 10 bright collections of stars and realized that it appeared the galaxy was moving way slower than they expected.
That would imply to the researchers that NGC1052-DF2 was missing the dark matter that many astronomers think makes up the vast majority of most galaxies’ mass.
Dark matter, you might remember, describes a problem more than a solution. Observations of the universe’s gravity seem to demonstrate more mass than astronomers can measure with their telescopes, perhaps five to six times more. Physicists generally think there’s a new kind of matter yet to be detected, though many instead argue that the laws of gravity have a hole. You can tell a galaxy’s mass based on how quickly it rotates—the more mass it has, the faster it would have to spin in order not to collapse. Most galaxies rotate too fast, while, according to Yale University scientist Pieter van Dokkum’s team, NGC1052-DF2 barely rotates at all.
Nearly all news outlets who covered the story (again, including me) generally reported the findings of the Nature paper without serious doubt. But some astronomers aren’t convinced.
At the center of the discussion is statistics. It’s mathematically difficult to make any conclusions using very small datasets, especially when you’re talking about just 10 clusters of stars in an entire galaxy, explained Nicolas Martin, astronomer at the Observatory in Strasbourg in France said in a Twitter thread. He and others crunched the data differently, and found that sure, maybe the galaxy was missing dark matter, but maybe it wasn’t. “The current data set doesn’t warrant such a strong conclusion,” he wrote. He’s since published the analysis with others, including Collins, on the arXiv server.
One of the disagreements, for example, stems from what to do with one of the 10 globular clusters that seems to be an outlier from the other nine based on how it moves. Both groups weigh it differently, Collins told me.
Van Dokkum has since addressed some of the concerns on a personal website, and thought the debate was “missing the forest from the trees.” He noted to Gizmodo in an email that folks generally agree with a similar velocity spread of the globular clusters, one that implies far less dark matter than the average galaxy—so it’s still “lacking” dark matter, but maybe not “missing” dark matter. But Collins responded to me that if you try to base the mass of more familiar dark matter-filled galaxies on just 10 specially selected globular clusters, you can make them, too, appear to not have any dark matter.
There are other rebuttals to Van Dokkum’s claims, including another arXiv paper discussing whether the observation really challenges alternative theories to explain the source of the stuff we call “dark matter.” Another discusses the behavior of these “ultra-diffuse” galaxies more generally.
And the debate has been going on for several weeks on Twitter. One astronomy grad student, Mia de los Reyes at CalTech in California, even turned the discussion into an American Chopper meme:
Original study author Van Dokkum himself doesn’t mind the debate—he calls it “excellent,” and “exactly what we are all supposed to do, trying to replicate each other’s results and looking for loopholes in the interpretation.” He told Gizmodo he also thought it was good to see the use of social media and the arXiv preprint server to give voice to younger astronomers with good ideas.
It would take a lot to convince Collins that the galaxy was truly missing dark matter’s effects. “You’d need significantly more data than they have presented here,” she said.
But mainly this goes to show science at its very core: It’s an ever-changing story where evidence and debate take us closer to the truth. And it’s a good reminder of something that lots of science writers, including me, didn’t apply to this paper: We need to remain skeptical about any new results until the larger science community has had time to digest and debate them. | <urn:uuid:8daeea10-3a24-4af2-99fb-f9784faa40d4> | 3.015625 | 1,129 | Truncated | Science & Tech. | 41.241781 | 95,501,253 |
One-year-old rope grown blue mussels (Mytilus edulis L.) were grown in experimental lantern nets at two depths (2 and 6 m below the surface) in two different positions (inflow and outflow) off a raft in Loch Etive on the west coast of Scotland. Shell and tissue growth, and mortality were recorded. Water temperature, salinity and food availability were also monitored over the experimental period. There were no significant differences in the length, live weight, wet meat weight, dry meat weight and ash-free dry meat weight between depths (P > 0.05). However, position had a significant effect on these parameters as mussels located at the inflow of the raft differed significantly from those at the outflow of the raft (P < 0.05). Particulate organic matter (POM) and chlorophyll a (Ch a) were significantly higher at the inflow than the outflow of the raft (P < 0.05), but depth had no effect on POM and Ch a (P > 0.05). The results show that food concentration was higher in the inflow of the raft than the outflow. In the light of these results, recommendations for better management of Scottish raft mussel cultivation are discussed.
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Choose a citation style from the tabs below | <urn:uuid:44133ebf-e839-4433-8653-89896bd774e8> | 2.96875 | 286 | Academic Writing | Science & Tech. | 54.220418 | 95,501,293 |
HTML noscript Tag
By Stephen Bucaro
The HTML <noscript> tag is used to define alternate content for users who have a browser that doesn't
support script or that have disabled scripts in their browser. Today, the web is highly dependent upon scripts
and any user whose browser does not support scripting is not going to have a useful browsing experience.
So the main purpose of the noscript tag today is to handle users that have disabled scripts in their browser.
Since the main motive for a user to disable scripts in their browser is to block advertising or assist in
other copyright violations, the noscript tag can be used to redirect such users to a page that explains why
they are being booted from your website. An example of use of the noscript tag is shown below:
<noscript><meta http-equiv="refresh" content="2000; url=http://bucarotechelp.com/search/unblock.asp" /></noscript>
Whether the <noscript> tag can be used in the or sections of a webpage depends upon the page's
!DOCTYPE declaration. With any !DOCTYPE declaration previous to html5, the <noscript> tag can be used only in
the <body> section. With the html5 !DOCTYPE declaration <!doctype html>, the <noscript> tag can be used in
either the <head> or <body> sections of a webpage. When used inside the <head> section,
<noscript> can contain only <link>, <style>, and <meta> elements.
If a browser doesn't support script or has scripts disabled, the script code will not be executed but will be
visible to the user. One common practice is to use the comment tag to hide scripts from browsers without support
for scripts. This is shown below:
However any user with or without support for scripts can view the page's script code by clicking on the browsers
View Source button.
More HTML Code:
• Checkbox Basics
• Form Input Labels
• HTML Blockquote Basics
• HTML abbr and acronym Tag
• Use HTML Target Attribute to Specify Where to Open Document
• HTML center Tag
• HTML5 Input Type - URL
• HTML5 Spinbox Control
• HTML5 role Attribute
• HTML dfn Tag | <urn:uuid:e9ba3681-6f82-4969-8550-0131abfe8a06> | 2.96875 | 495 | Documentation | Software Dev. | 56.126145 | 95,501,297 |
[Low sunspot numbers correlate very well with colder times. We have just had 7 higher than average sunspot cycles (11 years each) and temps have been warmer than “usual.” – Bob]
By Anthony Watts – Re-Blogged From http://www.WattsUpWithThat.com
Over the weekend, we reviewed the state of the solar data for March 2017. Now, there’s a two week straight lack of sunspots, the longest stretch since 2010.
The sun is currently blank with no visible sunspots and this is the 14th straight day with a blank look which is the longest such stretch since April 2010 according to spaceweather.com. Historically weak solar cycle 24 continues to transition away from its solar maximum phase and towards the next solar minimum. In April 2010 – the last time there was a two week stretch with no visible sunspots – the sun was emerging from the last solar minimum which was historically long and deep. There have already been 26 spotless days in 2017 (34% of the entire year) and this follows 32 spotless days last year which occurred primarily during the latter part of the year. The blank look to the sun will increase in frequency over the next couple of years leading up to the next solar minimum – probably to be reached in late 2019 or 2020. By one measure, the current solar cycle is the third weakest since record keeping began in 1755 and it continues a weakening trend since solar cycle 21 peaked in 1980. One of the impacts of low solar activity is the increase of cosmic rays that can penetrate into the Earth’s upper atmosphere and this has some important consequences.
Comparison of all solar cycles since 1755 in terms of accumulated sunspot number anomalies from the mean value at this stage of the solar cycle. Plot courtesy publication cited below, authors Frank Bosse and Fritz Vahrenholt
Third weakest solar cycle since 1755
A recent publication has analyzed the current solar cycle and has found that when sunspot anomalies are compared to the mean for the number of months after cycle start, there have been only two weaker cycles since observations began in 1755. Solar cycle 24 began in 2008 after a historically long and deep solar minimum which puts us more than eight years into the current cycle. The plot (above) shows accumulated sunspot anomalies from the mean value after cycle start (97 months ago) and only solar cycles 5 and 6 had lower levels going all the way back to 1755. The mean value is noted at zero and solar cycle 24 is running 3817 spots less than the mean. The seven cycles preceded by solar cycle 24 had more sunspots than the mean.
Daily observations of the number of sunspots since 1 January 1900 according to Solar Influences Data Analysis Center (SIDC). The thin blue line indicates the daily sunspot number, while the dark blue line indicates the running annual average. Last day shown: 28 February 2017. (Graph courtesy climate4you.com) | <urn:uuid:423f5eb3-5592-4671-8901-7437effb01ab> | 3.03125 | 612 | News Article | Science & Tech. | 55.016829 | 95,501,304 |
Structured programming is a subset of procedural programming. It is also known as modular programming. Corrado Bohm and Guiseppe Jacopini first suggested structured programming language. It is a logical programming method that is considered a precursor to object-oriented programming (OOP). Its main purpose to enforce a logical structure on the program being written to make it more efficient and easier to understand and modify.
The structured programming language allows a programmer to code a program by dividing the whole program into smaller units or modules. Structured programming is not suitable for the development of large programs and does not allow reusability of any set of codes. It is a programming paradigm aimed at improving the quality, clarity, and access time of a computer program by the use of subroutines, block structures, for and while loops. This paradigm follows the top-down approach. Some of the programming languages initially used for structured programming such as C, C++, C#, PHP, Ruby, PERL, ALGOL, Pascal, PL/I and Ada. C++ language code can be either structured, or object-oriented.
C is a structured programming language because to solve a massive problem. C programming language divides the problem into smaller modules called functions. The structured program theorem provides the theoretical basis of structured programming. It states that three ways of combining programs—sequencing, selection, and iteration. These three ways are sufficient to express any computable function. C++ grew from C which is a structured programming language. In structured programming, you have data, and you can write functions to process the data. Our structured Programming homework help experts provide solutions to you at codeavail.com. Our experts have good knowledge of structured programming language. You can get all material related to programming from our experts at codeavail.com.
The code that is written may appear in different parts of the program. It can be vulnerable to various problems because of its location. Programs have variables, which means that they can take on different values at different parts of the program.
Its lack of availability in structured programming means that programs will be longer.
Information hiding involves isolating design decisions in a computer program that have the greatest chance to change. This protects other parts of the program from modifications if the design decision is changed.
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If you are facing problems with structured programming assignment help, then you can submit your assignments at firstname.lastname@example.org. You can also submit your assignments through this link Submit work. Our Structured Programming Assignment Help experts always deliver the assignment’s solution at very affordable Price. | <urn:uuid:011b50e2-078c-42b6-b18f-6f534590c996> | 3.796875 | 746 | Product Page | Software Dev. | 36.26815 | 95,501,305 |
The biological information that makes us unique is encoded in our DNA. DNA damage is a natural biological occurrence that happens every time cells divide and multiply. External factors such as overexposure to sunlight can also damage DNA.
Results from computer simulations show that it is energetically less expensive to bend mismatch-containing, defective DNA (G:T, C:C, C:T, G:A, G:G, T:T, A:A, A+:C) vs. non-defective DNA (containing A:T or G:C base pairs). DNA repair mechanisms likely take advantage of this feature to detect defective DNA based on an increased bending propensity.
Understanding how the human body recognizes damaged DNA and initiates repair fascinates Michael Feig, professor of biochemistry and molecular biology at Michigan State University. Feig studies the proteins MutS and MSH2-MSH6, which recognize defective DNA and initiate DNA repair. Natural DNA repair occurs when proteins like MutS (the primary protein responsible for recognizing a variety of DNA mismatches) scan the DNA, identify a defect, and recruit other enzymes to carry out the actual repair.
"The key here is to understand how these defects are recognized," Feig explained. "DNA damage occurs frequently and if you couldn't repair your DNA, then you won't live for very long." This is because damaged DNA, if left unrepaired, can compromise cells and lead to diseases such as cancer.
Feig, who has used national supercomputing resources since he was a graduate student in 1998, applied large-scale computer simulations to gain a detailed understanding of the cellular recognition process. Numerical simulations provide a very detailed view down to the atomistic level of how MutS and MSH2-MSH6 scan DNA and identify which DNA needs to be repaired. Because the systems are complex, the research requires large amounts of computer resources, on the order of tens of millions of CPU core hours over many years.
"We need high-level atomic resolution simulations to get insights into the answers we are searching for and we cannot run them on ordinary desktops," Feig said. "These are expensive calculations for which we need hundreds of CPUs to work simultaneously and the Texas Advanced Computing Center (TACC) resources made that possible."
As a user of the National Science Foundation's Extreme Science and Engineering Discovery Environment (XSEDE), Feig tasked TACC's Ranger and Stampede supercomputers to accelerate his research. Ranger served the national open science community for five years and was replaced by Stampede (the sixth most powerful supercomputer in the world) in January 2013.
DNA chains are made of four precise chemical base pairs with distinct compositions. In a paper published in the Journal of Physical Chemistry B (April 26, 2013), Feig and his research team showed that the identification and initiation of repair depended on how the MutS protein bound with the base mismatches.
"We believe that DNA bending facilitates the initial recognition of the mismatched base for repair," Feig said. "Normal DNA is like a stiff piece of rubber, relatively straight. It becomes possible to bend the DNA in places where there are defects."
The biological repair machinery seems to take advantage of this propensity by ‘testing' DNA to determine whether it can be bent easily. If that is the case, the protein has found a mismatch and repair is initiated.
"When the MutS protein is deficient in certain people, they have a high propensity to develop certain types of cancer," Feig said. "We're interested in understanding, first of all, how exactly this protein works. The long-term idea is to develop strategies for compensating for this protein, basically substituting some other mechanism for recognizing defective DNA and enabling repair."
The strongest link between diseases and defects from the MutS protein has been made for a specific type of genetically inherited colon cancer.
"If an essential protein like MutS is missing or less than adequate, then the cells will not behave in a normal way," he explained. "They will turn cancerous. The cells will refuse to die and proliferate in an uncontrollable state."
In these cases, cancer is not a result of damaged DNA, but occurs because of a problem in the DNA repair mechanism itself.
"It probably has effects on many other cancers as well, because all the cancers are ultimately linked to defective DNA," he said. "If DNA damage is not recognized and repaired in time then it can lead to any type of cancer. It is a fairly generic mechanism."
According to Matt Cowperthwaite, TACC's medical informatics programs coordinator, Feig's research is enormously important for advancing our understanding of how cells repair the mistakes that inevitably occur during DNA replication. "For the first time, we have a mechanistic insight of how MutS finds mutations. This is extremely important research because the process of mutation underlies some of the deadliest diseases to affect humans, such as cancer."
Research in this area, being very fundamental in nature, throws up many challenges, but its potential in future impact, Feig believes, is tremendous."There are many proteins with different and important biological functions," he said. "Understanding their functions and roles in the human body will be a driving force for research in the near future."
Paromita Pain | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:1b767e60-7c72-4a9e-a8af-ca6e4f09fd29> | 3.59375 | 1,679 | Content Listing | Science & Tech. | 37.213633 | 95,501,321 |
posted by Meder
Inside an insulated container, a 250-g ice cube
at 0°C is added to 200 g of water at 18°C.
(i) What is the final temperature of the system?
(ii) What is the remaining ice mass?
To melt all of the ice, 250g*80cal/g = 20,000 calories must be added. The already-liquid water can transfer only 200*18 = 3600 calories as it cools from 18 to 0 C. Therefore some of the ice remains at equilibrium. (i) The final temperature is 0 C.
(ii) Bringing all of the original liquid from 18C to 0C transfers 3600 cal to the ice. That is enough to melt 3600/80 = 45 g.
205 g of ice remains. | <urn:uuid:e2ac49bd-9389-4e2e-bcf7-e18fc3566ea4> | 3.125 | 169 | Q&A Forum | Science & Tech. | 89.677467 | 95,501,322 |
Astronomers using a powerful radio telescope in Chile said Wednesday that they had discovered sugar molecules, one of the building blocks of life, orbiting a young star similar to the Sun.
“This is the first time sugar been found in space around such a star,” the European Southern Observatory (ESO), which is administering the project, said Wednesday.
The astronomers found glycolaldehyde, a sugar compound described as essential to the existence of life, in the gas surrounding the star, located some 400 light-years from Earth, it said.
The discovery “shows that the building blocks of life are in the right place, at the right time, to be included in planets forming around the star.”
Because the star is similar to our sun, the finding “shows that some of the chemical compounds needed for life existed in this (solar) system at the time of planet formation,” the ESO said.
The discovery was made possible by the high sensitivity of the Atacama Large Millimeter/submillimeter Array (ALMA), an international project still under construction and slated for completion in 2013.
ALMA has 66 antennas exploring the universe via radio waves emitted by galaxies, stars and other bodies not captured by optical and infrared telescopes, which only receive light.
The ESO operates three sites in Chile.
The Very Large Telescope (VLT) array — a cluster of four telescopes that can view objects four billion times fainter than those visible to the naked eye — is housed at the ESO’s Paranal site in Chile’s Atacama Desert.
The ESO is supported by Austria, Belgium, Brazil, Britain, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden and Switzerland. | <urn:uuid:5bbb0c81-138f-4e64-aeab-3dc09de31ee5> | 3.375 | 372 | News Article | Science & Tech. | 28.180682 | 95,501,340 |
Maybe start saving up?
Things are heating up.
A look at the process which makes life on Earth possible — but may topple our society if taken too far.
“Come to the dark side” the Moon, presumably, told China. China decided to go.
A bad record to set.
In America, every political group comes with its own views on climate change.
100°F isn’t something that puts a smile on your face.
The Arctic’s getting really hot.
Emissions work both ways. Well, worked.
Hot, droughty, floody, deadly.
This is not good news.
We use so much of everything so fast that it’s literally killing the planet.
A tiny algae could spiral out of control with huge consequences.
A research team from University College in London has calculated that in the last five years, the ten biggest cities have increased their climate adaptation spending by a quarter. But they also found that it’s capital, not people, that we’re investing the most to protect. Beyond the moral implications this entails, it also means that poor but highly populated cities and
This Friday, the tiny island nation of Fiji put up a big flag on the map by becoming the first country in the world to ratify the UN climate deal put together last December at the Paris COP21.
According to the Chinese Central Television, China wants to land rover on the far side of the moon, also know as the dark side of the moon, by 2020. This would make it the first nation to land a spacecraft of any sort there. First, the rover will orbit the moon piggy-bagged by the Chang’e 4 spacecraft then later deployed to a launch site. The rover will carry out some scientific missions, but the main goal really is to test China’s space launching capabilities, but also as a show of force. Flex those muscles, sort to speak. Some analysts, however, speak out that there might be more to it, namely a bid for the moon’s resources. | <urn:uuid:a5822372-d685-4d4f-9f16-931534f3496f> | 2.78125 | 432 | Content Listing | Science & Tech. | 65.30701 | 95,501,343 |
you notice that:
- The positive charges are still at the top (this is hydrogen, it is the lightest)
- The negative charges at the bottom of the first (ie the monatomic oxygen, it is relatively heavier than hydrogen).
what does that mean
Questioned the theory "evaporation-condensation rain" and the water cycle is incomplete, it lacks two steps (decomposition and synthesis of water) natural water cycle is: (in one page)
Flash + Thunder + Water (Rain) = one operation,how ?
1-Photolysis (dissociation or photolysis) of ocean water consists of the decomposition of the water molecule into hydrogen molecules (H2) and atom (O) under the effect of solar radiation in the ultraviolet.
Due to the depletion of the ozone layer in certain regions of the globe, sunlight reaches the surface of the earth and enriched with UV-C radiation (λ = 100 -280nm) to shorter wavelength (Lloyd, 1993), between 11 and 16 pm their luminous intensity is still significant and more to 14 h, these UV through a smaller distance in the atmosphere and are not intercepted by the ozone molecules, they are able to the surface of the earth and the water molecules dissociate into H2 and O free, the rate is higher in the mountains, and are reverberated through water and snow.
2- The molecules (H2) and atoms (O) are driven by the currents of warm air upward, dry representing a mechanical force that opposes that of cold air downdrafts, there is opposition two mechanical forces of compression where the volume of air including a mixture of oxygen (O) and hydrogen
(H2) which both agitated by the fact that the compression, friction and the effect of solar radiation (ionization ) are charged with positive electricity and negative for hydrogen for oxygen and a favourable compression ratio, the two gases combine in an explosive chemical reaction (synthesis of water is explosive), they form the water (rain).
H2 --> 2H⁺ + 2é-
½ O2 + (2H⁺) + 2é- --> explosion – Flash-Thunder -Rain (H2O + heat)
3-The light of the lightning reaches us first (299,792,458 m / s), the sound of the explosion was thunder (340 m / s) in the second and finally the raindrops whose fall speed is lower to those of the light and sound.
So: Flash + Thunder + water = one operation
Nitrogen is known by its inertia to respond, the synthesis of water is exothermic, it will form ammonia in a reversible reaction
N2+3H2 <--2NH3, and nitrogen oxides.H2 molecules were free to combine with oxygen atoms by the same method.
4- How to form a cloud?
These are the first explosive reactions of synthesis of water that are responsible for the birth of a cloud, and as they are exothermic, cold air that surrounds it even contracts (compression), the remaining amounts hydrogen and oxygen react in turn within the cloud to further form water, there is shown out of the lightning from the cloud, each storm cell can cause more than 100 flashes per minute
Until exhaustion of hydrogen, leaving only water suspended in the cloud whose molecules coalesce and form a steady rain without lightning. Thunder is in fact only the sound of the noise of the explosions. So we understand that
"lightning + thunder + rain = one operation" and then "condensation--> rain".
It occurs 24 hours around the Earth between 2000-5000 storms per second
that is to say it forms water in the atmosphere from 172,800,000 to 432,000,000 times between the atmosphere by then coalesced synthesis but the original source of his training remains. | <urn:uuid:cfb18f49-14f8-4d1b-bdbd-8ef96e3ab324> | 3.46875 | 793 | Tutorial | Science & Tech. | 25.201574 | 95,501,346 |
Geitoneura acantha ocrea (Guest) (Ringed Xenica)
Interesting aspects: A pretty satyr, restricted to the South Mount Lofty Ranges in South Australia. It is a relict from probably the end of the last ice-age when the southern areas of South Australia were cooler and received a much higher rainfall. The sexes are similar in appearance, but can be readily distinguished by the prominent silvery sex brand present in each forewing of the males which occurs transversely across the centre of the wing upperside. Males will establish territories by perching on or near the ground in clear, sunny areas, waiting for newly emerged females. When fertile females are chased by males, they signal to the males that they are fertile by settling on the ground and fluttering their wings. This signal makes the males quickly lose interest.
The butterflies have an irregular flight, and prefer to settle on or near the ground. Like most satyrs, the wing undersides are cryptically camouflaged. It is difficult to detect these butterflies when they are settled with wings closed and erect, owing to their close resemblance to the ground, or to dead leaf and plant debris, particularly in dappled forest light. The butterflies are sometimes more common along the base of cool, shady rock faces where their camouflage is nearly perfect. On very hot days the butterflies will congregate together in cool, shady areas.
Usually a difficult butterfly to approach when settled as any quick movement or the least bit of noise will make it fly. If careful, it can be approached to within 1-2 m before it explodes away. Depending on the amount of scare, the butterfly will often only fly a short distance before settling again.
Larval food-host: Native and introduced grasses including *Brachypodium distachyon (false brome), *Ehrharta longiflora (annual veldt grass), Microlaena stipoides (meadow rice-grass), *Pennisetum clandestinum (kikuyu), Poa species including P. clelandii (matted tussock grass), P. tenera (slender tussock grass), Themeda triandra (kangaroo grass) (Poaceae). Early instar larvae feed on the hostplant leaves. The larger final instar larvae devour all the softer parts of the hostplant including young seed heads.
Eggs: Small, initially pale yellow or white, turbinate (expanding basally), the base and apex are flat, moderately thick shelled, with well developed vertical ribs numbering 24-27, which do not extend onto the apical flattened area. The top flattened area is not rimmed with a ridge. Laid singly on dead twig and similar debris that is lying on the ground adjacent to the hostplant. If the egg is fertile it becomes purple speckled after a couple of days. Larva development within the egg usually commences immediately after being laid, and larvae begin to emerge in about 15 days. The empty egg shell is then eaten. (In captivity, most of the newly emergent larvae then become immobile. Some eventually move off to look for the hostplant, while the remainder stay put and would eventually die unless forcibly moved onto hostplant). However, some delayed egg development occurs, and some developed larvae remain inside the egg until wetted by rain. Some larvae do not emerge until late April, some two months after the eggs are laid.
Larvae: Initially pale grey with fine longitudinal purplish brown lines, with numerous long pale hairs that emanate from black bases. These hairs are knobbed at the tips. The head is finely rugose, dark brownish black with some long hairs. In the first instar, the head is not horned and the rear end is only vestigially forked. After eating the green leaves of the hostplant, the larvae gradually turn green and acquire indistinct yellowish lines. The second instar is green with longitudinal yellow and dark green lines, the head is green and has a pair of vestigial conical horns, and the rear end has a short fork typical for the Satyrinae. The horns and forked tail are pink tipped. Later instars are either green or brown, and with successive instars, the body hairs are replaced by secondary setae, and the head acquires increasingly larger horns.
The mature larvae are long cylindrical shaped, tapering anteriorly and posteriorly, slightly flanged laterally, about 27-29 mm long, usually green coloured, with narrow yellow lateral and subdorsal lines, the latter edged with dark green, and there is a dark green dorsal line. The body is without long hairs, but bears numerous pointed secondary setae. The head is large, finely rugose with numerous short hairs, with a well developed pair of flattened pointed horns, green coloured with the perimeter of the head outlined in maroon which is further edged yellow posteriorly, and there is sometimes a pair of large dark maroon spots in the front just above the mouth. The rear end is forked, marked yellow laterally and the tips are pink. Brown larvae are occasionally seen, in which all the green colour is replaced by brown, with the dark aspects and yellow and pink markings remaining the same. These brown larvae presumably develop in response to a hostplant with many dead leaves.
The immature larvae nibble the leaf edges of the hostplant, but later instars devour the entire leaf and also other soft green parts of the grass. Early instar larvae remain exposed on the hostplant, but later instars hide around the base of the hostplant coming out at night to feed. The latter larvae emerge soon after sunset to climb the hostplant, and move very slowly. If disturbed while feeding, the larvae will release their hold on the grass and drop to the ground, remaining rigid for some time in whatever position they were in, at the time of the disturbance. They are extremely well camouflaged on the hostplant and very difficult to detect. The larvae feed throughout winter and pupation takes place in late spring and early summer.
Pupae: Small, stout, about 13 mm long, with a roughened surface, rounded posteriorly, wedge shaped anteriorly with a pair of small horns, dorsally keeled, ridged laterally at the wing junction, and also dorsally across the abdomen. A few small protuberances ventrally. Usually green coloured, with some darker green markings, suffused yellow which is best developed ventrally, with six pairs of raised yellow subdorsal abdominal spots, the dorsal keel and the lateral and abdominal ridges are outlined with dark brown edged pale yellow, the yellow outline is strongly developed on the abdominal ridge. There is also a pair of raised black dots ventrally. As with the larvae, some pupae are brown coloured, in which the green colouration is replaced by brown. However, a few days before the butterfly emerges, a green pupa will turn brown as the butterfly inside the pupal shell develops its natural brown colour. First the wing cases turn brown, then later the head and thorax, and finally the abdomen. Brown larvae do not necessarily produce brown pupae. The pupa is suspended head downwards by a cremaster, either from the hostplant, or from a log, stick, rock or another plant adjacent to the hostplant. The pupa stage lasts about three weeks. Near Adelaide it is about 17-19 days during early summer.
Flight period in S.A.: Only one brood a year with an extended flight from late November to late March. The males emerge earlier than the females. The bulk of the males emerge during late December - early January, while the bulk of the females emerge during late January - early February. By the end of February the flight is mostly over.
Distribution: The butterfly occurs only along the South Mount Lofty Ranges in the Adelaide Hills and along the west side of the Fleurieu Peninsula. Enigmatically, the butterfly does not occur on Kangaroo Island or in the Lower Southeast of the state where suitable habitat is present. The butterfly is much more common in the eastern mainland states of Australia where another subspecies occurs.
Habitat: The butterfly occurs in cool, damp shady woodland and forest areas receiving more than about 600 mm of annual rainfall, and having its grass hostplant in the understorey remaining in a green condition all year round. Its original habitat (prior to the introduction of invasive grasses from overseas), was probably the Poa grasslands which require moist conditions.
Conservation Status in S.A.: Rare.
Threats: Bushfires, drought, and urban and agricultural expansion are the main threats. As the habitat of the butterfly is now very limited, introduced woody weeds such as blackberry, boneseed, bridal creeper, broom and gorse also have the capacity to be a serious threat by choking off its hostplant and habitat.
Conservation Strategy: Population numbers do not seem to have deteriorated over the past 30 years, and it is likely the butterfly is reasonably well protected in the conservation parks along the Mt Lofty Range. The introduced weeds will have to be monitored in its conserved habitat, and destroyed where necessary.
Author: R. GRUND, © copyright 10 September 2000, all rights
Last update 29 April 2002. | <urn:uuid:e25000c5-89c8-4155-9a26-fbe87bd6eaa1> | 3.0625 | 1,943 | Knowledge Article | Science & Tech. | 42.551582 | 95,501,364 |
Impact of an introduced ant on native rain forest invertebrates: Pheidole megacephala in monsoonal Australia
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Pheidole megacephala is an exotic ant species that has severely affected native invertebrate biodiversity throughout the tropics. Its impacts have been documented extensively in relatively depauperate invertebrate communities, but not in species-rich habitats such as tropical rain forests. Here we describe the local distribution of P. megacephala and its impacts on native invertebrate assemblages in and around a rain forest patch at Howard Springs, in Australia's monsoonal tropics. P. megacephala was found to be confined to a single area of approximately 25 ha, with its distribution centered on drainage lines and the rain forest. Significant but weak correlations were found between its abundance and vegetative canopy cover (positive) and distance from the rain forest (negative). In the most heavily infested area within the rain forest, the abundance of P. megacephala was 37–110 times that of total native ant abundance found within uninfested plots, as measured by pitfall traps. The abundance and richness of native ants and other invertebrates were significantly reduced in litter samples, pitfall catches and foliage beats where P. megacephala was present, inversely relative to the abundance of P. megacephala. Only two individuals of a single native ant species were found within the most infested plot, with native ant richness being reduced to about half in the least infested plot. The most persistent functional groups of native ants in infested plots were Cryptic species, which forage primarily within soil and leaf litter, and Opportunists, which exhibit highly generalised foraging behaviour. The highest abundance of P. megacephala corresponded with a 42–85% decrease in the abundance of other native invertebrates. Insect larvae were totally absent from foliage beats collected at the most heavily infested plot. P. megacephala was found overall to be expanding its range, averaging 12 m range expansion in the dry season and contracting 7 m in the wet season. It is able to spread into surrounding savanna habitats by occupying relatively sheltered microsites, such as beneath logs and at the bases of trees. However, it is unlikely to attain high population densities in open savanna habitats because of its relative intolerance of desiccation, and the prevalence of behaviourally dominant native ant species. Howard Springs is currently the only rain forest patch in monsoonal Australia known to be infested by P. megacephala, but clearly this ant is a serious potential threat to the region's rain forest invertebrate fauna.
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Working as part of the National Science Foundation’s West Antarctic Ice Sheet Divide (WAIS Divide) Ice Core Project, a team of scientists, engineers, technicians, and students from multiple U.S. institutions have recovered a 580-meter (1,900-foot) ice core – the first section of what is hoped to be a 3,465-meter (11,360-foot) column of ice detailing 100,000 years of Earth’s climate history, including a precise year-by-year record of the last 40,000 years.
The dust, chemicals, and air trapped in the two-mile-long ice core will provide critical information for scientists working to predict the extent to which human activity will alter Earth’s climate, according to the chief scientist for the project, Kendrick Taylor of the Desert Research Institute of the Nevada System of Higher Education. DRI, along with the University of New Hampshire, operates the Science Coordination Office for the WAIS Divide Project.
WAIS Divide, named for the high-elevation region that is the boundary separating opposing flow directions on the ice sheet, is the best spot on the planet to recover ancient ice containing trapped air bubbles – samples of the Earth’s atmosphere from the present to as far back as 100,000 years ago.
While other ice cores have been used to develop longer records of Earth’s atmosphere, the record from WAIS Divide will allow a more detailed study of the interaction of previous increases in greenhouse gases and climate change. This information will improve computer models that are used to predict how the current unprecedented high levels of greenhouse gases in the atmosphere caused by human activity will influence future climate.
The WAIS Divide core is also the Southern Hemisphere equivalent of a series of ice cores drilled in Greenland beginning in 1989, and it will provide the best opportunity for scientists to determine if global-scale climate changes that occurred before human activity started to influence climate were initiated in the Arctic, the tropics, or Antarctica.
The new core will also allow investigations of biological material in deep ice, which will yield information about biogeochemical processes that control and are controlled by climate, as well as lead to fundamental insights about life on Earth.
Says Taylor, “We are very excited to work with ancient ice that fell as snow as long as 100,000 years ago. We read the ice like other people might read a stack of old weather reports.”
The WAIS project took more than 15 years of planning and preparation, including extensive airborne reconnaissance and ground-based geophysical research, to pinpoint the one-square-kilometer (less than a square mile) space on the 932,000-square-kilometer (360,000-square-mile) ice sheet that scientists believe will provide the clearest climate record for the last 100,000 years.
With only some 40 days a year when the weather is warm enough for drilling – yesterday’s temperature was a balmy -15 degrees Celsius (5 degrees Fahrenheit) – it is expected to take until January 2010 to complete the fieldwork.
For the project, Ice Coring and Drilling Services of the University of Wisconsin-Madison built and is operating a state-of-the-art, deep ice-coring drill, which is more like a piece of scientific equipment than a conventional rock drill used in petroleum exploration. The U.S. Geological Survey National Ice Core Laboratory in Denver designed the core handling system. Raytheon Polar Services Corporation provides the logistical support. The NSF Office of Polar Programs-U.S. Antarctic Program funds the project. The core will be archived at the National Ice Core Laboratory, which is run by the USGS with funding from NSF.
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Astronomy Picture Of the Day (APOD)Cerealia Facula
Cerealia Facula, also known as the brightest spot on Ceres, is shown in this stunning mosaic close-up view. The high-resolution image data was recorded by the Dawn spacecraft, in a looping orbit, from altitudes as low as 34 kilometers (21 miles) above the dwarf planet's surface.
Dark Slope Streaks Split on Mars
What is creating these dark streaks on Mars? No one is sure. Candidates include dust avalanches, evaporating dry ice sleds, and liquid water flows. What is clear is that the streaks occur through light surface dust and expose a deeper dark layer.
Moon and Venus over Cannon Beach
What's that spot next to the Moon? Venus. Two days ago, the crescent Moon slowly drifted past Venus, appearing within just two degrees at its closest. This conjunction, though, was just...
Neutrino Associated with Distant Blazar Jet
With equipment frozen deep into ice beneath Earth's South Pole, humanity appears to have discovered a neutrino from far across the universe. If confirmed, this would mark the first clear detection of cosmologically-distant...
Rings Around the Ring Nebula
There is much more to the familiar Ring Nebula (M57), however, than can be seen through a small telescope. The easily visible central ring is about one light-year across, but this remarkably deep exposure...
A Nibble on the Sun
The smallest of the three partial solar eclipses during 2018 was just yesterday, Friday, July 13. It was mostly visible over the open ocean between Australia and Antarctica. Still, this video frame...
Star Trails and the Bracewell Radio Sundial
Sundials use the location of a shadow to measure the Earth's rotation and indicate the time of day. So it's fitting that this sundial, at the Very Large Array Radio Telescope Observatory in New Mexico, commemorates the history of radio astronomy and radio astronomy pioneer Ronald Bracewell.
Only 11 million light-years away, Centaurus A is the closest active galaxy to planet Earth. Spanning over 60,000 light-years, the peculiar elliptical galaxy also known as NGC 5128, is featured in this sharp telescopic view.
Symbiotic R Aquarii
You can see it change in brightness with just binoculars over the course of a year. Variable star R Aquarii is actually an interacting binary star system, two stars that seem to have a close, symbiotic relationship.
Noctilucent Clouds over Paris Fireworks
It's northern noctilucent cloud season -- perhaps a time to celebrate! Composed of small ice crystals forming only during specific conditions in the upper atmosphere, noctilucent clouds may become visible at sunset during late summer when illuminated by sunlight from below. | <urn:uuid:d0cd4bf3-4266-4e23-8f11-7ca93191f4cd> | 3.78125 | 594 | Content Listing | Science & Tech. | 48.434174 | 95,501,406 |
Outer Space & Universe
Outer Space & Universe
Space, also known as outer space, is the near-vacuum between celestial bodies. It is where everything (all of the planets, stars, galaxies and other objects) is found.
On Earth, space begins at the Kármán line (100 km above sea level). This is where Earth's atmosphere is said to stop and outer space begins. This is not a firm boundary but is a convention used by scientists and diplomats.
Items in space are free to move back and forth; up and down; and left and right. These three dimensions are what make 3D space. Items also move forward through time, which is sometimes called the fourth dimension.
The majority of space contains very little matter and so most of it is a vacuum. Scientists do not know how big space is but we do know that space is extremely big, and is always expanding.
According to the big bang theory, all matter and energy in the Universe was compressed into a very small space. Then it exploded and started expanding. Space is still growing in size today; this means the distance from one galaxy to distant galaxies is getting longer.
Gravity is the force that keeps the Moon in orbit around the Earth and the planets in orbit around the Sun. Gravity can stretch and bend space similar to how a heavy ball placed on a stretched sheet of rubber will cause the rubber to stretch. The scientist who discovered that space can bend is named Albert Einstein. How gravity bends space is part of his theory of general relativity.
Astronauts, Cosmonauts, Taikonauts and Spationauts
An astronaut is any person who is trained by NASA to travel and perform tasks in space. Although the space traveler may not necessarily be a United States citizen, each astronaut does go through a rigorous training regiment by the National Aeronautics and Space Administration. Other space travelers go by other names then astronaut depending on their country of origin.
In the United States, astronaut is derived from the Greek words ástron (star) and nautis (sailor). While, in Russia, a space traveler goes by the name космонавт (English: cosmonaut), which is derived from the Greek words kosmos (universe) and nautis (sailor). Westerners call a space traveler from China a taikonaut, based on the 1998 writings of Chiew Lee Yik and Chen Lan where the term tàikōng (great emptiness), Chinese for “space”. In China, the term yuháng yuán (universe navigator) is used for space traveler.
Only the United States of America (United States), Russia (earlier, the Union of Soviet Socialist Republics), and the People’s Republic of China (China) have sent manned spacecraft into space. Other countries have assisted these countries by sending their own space travelers on space missions. For instance, a French space traveler is called a spationaut (from the French word spationaute), which is derived from the Latin spatium (space) and Greek nautis (sailor). (plural in Greek nautes = sailors)
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Fmr. NASA astronaut Mike Massimino walks on the lunar surface in the virtual reality experience “A Moon for All Mankind” (AMFAM) at Samsung 837 in New York City.Credit: Space.com / footage courtesy Samsung / produced and edited by Steve Spaleta http://www
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We're looking at some serious flooding possible all up and down the East coast and into the South over the next 2 weeks. Also, the Heat surges over the next week will be shattering some records. The worst weather is still to be found in Asia Pacific. They
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Don't get cocky now. We've still got a lot of work today.The BIG eclipse is in 10 days. Let's be prepared. Asteroid Fight Club. Astonishers. American Bicycle Club.I am very proud of you. Y'all have all done a great job!God bless everyone! Let Peace rule!T
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The European Southern Observatory’s Very Large Telescope used it new adaptive optics mode, known as laser tomography, to capture an incredible view of Neptune. -- Full Story: https://www.space.com/41202-new-adaptive-optics-produces-stunning-views.htmlCred
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A new cycle of the NASA iTech initiative kicks off today with a call for technical solutions to fill gaps in areas identified as having a critical impact on future space exploration.The request for a five-page white paper is the first phase of 2018 NASA i
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European Space Agency (ESA) astronaut, well-known for his amazing imagery of Earth from the International Space Station, captured another amazing view. The video was “filmed 12.5 times faster than actual speed,” according to ESA. -- Read more about it: ht
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There are many heroes at NASA, and they’re not just astronauts. In this episode of “So You Want to Go to Mars?” we take a special behind the scenes look at spaceflight and discover the heroes that are solving the major challenges of our space missions tod
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I might be too happy to communicate properly right now.Thank you. Thank y'all. I love you. Y'all are amazing.You can find our Homework here Long Detailed Blog Entry 7/16:http://www.stormhamster.com/entry/e071618.htmFocused Blog Entry 7/17:http://www.storm
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On July 17, 1962, the American test pilot Bob White broke the world record for the highest altitude flight. He took off from Edwards Air Force Base in a rocket-powered X-15 aircraft and made it to an altitude of 314,750 feet. That's almost 60 miles! At th
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An uncrewed Cygnus OA-9 spacecraft departed the International Space Station on July 15, 2018. It will deorbit and burn up in the Earth's atmosphere is a few weeks. -- Full Story: https://www.space.com/41172-cygnus-leaves-space-station-orbital-boost.htmlCr
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WARNING: The images of the Sun are beautiful and mesmerizing but they might send a chill down your spine and stand up the hairs on your arms.God bless everyone.Thttps://www.paypal.me/THORnewsTshirtshttps://hitthebuttonbaby.com/THORNEWS PO BOX 35946HOUSTON
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https://www.paypal.me/THORnewsThe Euro & GFS forecast models continue to spin up some pretty wild scenarios a week from now. Multiple Fujiwhara Typhoons? The projected rain totals for some areas would be utter catastrophic. A form of that pattern will shi
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Honey Smacks is a Killer Cereal. They have Salmonella. The world is wild. Also, don't combine Tide Pods with Sal. God bless everyone,Thttps://www.paypal.me/THORnewsTshirtshttps://hitthebuttonbaby.com/THORNEWS PO BOX 35946HOUSTON TEXAS77235-5946http://www.
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The International Space Station is HOW big? As big as the #WorldCup field!
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NASA's Space to Ground is your weekly update on what's happening aboard the International Space Station. Got a question or comment? Use #spacetoground to talk to us.Learn more about the important research being operated on Station:https://www.nasa.gov/iss
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The Arecibo Observatory and the Green Bank Observatory pinged binary asteroid YE5 during a recent flyby of Earth. The asteroids were 3.7 million miles (6 million kilometers) away on June 21, 2018. -- Full Story: https://www.space.com/41154-rare-binary-ast
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The detection of a single neutrino by the IceCube neutrino telescope at the South Pole on Sept. 22, 2017 sparked a global effort to find its source. -- Full Story: https://www.space.com/41146-neutrino-source-blazar-cosmic-rays.htmlCredit: Space.com / anim
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Things are wild. I am feeling better. Would you like to buy me a drink?Stay cool.God bless everyone.Thttps://www.paypal.me/THORnewsTshirtshttps://hitthebuttonbaby.com/THORNEWS PO BOX 35946HOUSTON TEXAS77235-5946the excellent cranywxguy bloghttp://www.stor
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Who knows what this video will be?God bless everyone.Thttps://www.paypal.me/THORnewsTshirtshttps://hitthebuttonbaby.com/THORNEWS PO BOX 35946HOUSTON TEXAS77235-5946I am getting my editing chops back. | <urn:uuid:dbe1687e-8ede-4502-911f-563abfbeeeab> | 3.515625 | 2,187 | Content Listing | Science & Tech. | 67.106492 | 95,501,414 |
Radioactive Decay, Nuclear Fission and Nuclear Fusion Essay Sample
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Introduction of TOPIC
The fundamental difference between radioactive decay and nuclear fission is that, whereas radioactive decay is spontaneous, nuclear fission must be induced. In nuclear fission, when an unstable nucleus absorbs a neutron, it splits, emitting more neutrons and setting off a continuous chain reaction. This leads to products with nuclear masses around half those of the initial nuclei, whereas in radioactive decay, the initial and final nuclear masses are relatively close together. The other major difference is that fission releases considerably more energy than decay. This energy comes from mass lost in fission, according to the equation E = mc2, where E is energy, m is mass and c is the speed of light.
Synthesis of Elements in Stars
Stars produce their energy from nuclear fusion, in which nuclei join together to make larger nuclei. Hydrogen is used in normal-sized stars:
(e+ represents a positively charged electron, and ?e is a neutrino) This process requires temperatures of around 13 million K and pressures of around 300 billion atmospheres.6 When almost all of the hydrogen has fused, the helium nuclei can collide to make nuclei such as beryllium:7
This leads to the creation of further nuclei containing four nucleons: carbon, oxygen, neon and magnesium. Once all the helium has fused, further collisions take place between the created nuclei. This leads to the production of small amounts of hydrogen and helium, producing most of the first 18 elements, such as lithium:8
Lithium can also be produced by the collision of a Beryllium-7 nucleus and an electron. The nuclear process that takes place here is electron capture, in which an atom captures an electron, turning a proton into a neutron and releasing a neutrino. This happens by the weak interaction, like -decay:9
Smaller amounts of lithium can also be produced in the fission of some nuclei by cosmic rays and in supernovae, when heavy stars become unstable and explode.10
Producing Energy through Nuclear Fission and Fusion
In nuclear fission, an unstable nucleus absorbs a neutron, exciting the nucleus, causing it to oscillate and split into two smaller nuclei. This process releases more neutrons, causing more nuclei to split, and so on. This is shown in Fig. 211 with Uranium-235.
The energy produced by nuclear fission, by E = mc2, is 3.2×10-11 J per fission.12
Uranium-235 is used to produce energy by fission – see Fig. 313.
Controlling this reaction:
* Uranium-238 is mixed with uranium-235. Uranium-238 nuclei absorb neutrons but do not react by fission, breaking the chain in the reaction.
* Graphite moderators placed in between the uranium rods reduce the kinetic energy of the neutrons produced so they can induce fission.
* Boron-coated steel control rods absorb neutrons, and can be moved in and out of the reactor. If they are fully in, the reaction stops.
Nuclear fusion takes place when, under certain conditions, two nuclei fuse together. For example, with deuterium and tritium:14
The energy produced comes from the mass lost – 3.17×10-29 kg 15 16. By E = mc2, this gives out 2.86×10-12 J per fusion. On earth, for this to happen the nuclei must be in ionised plasma at temperatures of 15×108 C. The problem with this is that it must be kept away from the walls of the container to minimise he
at loss. To do this, a tokamak is used. This uses magnetic currents to keep the plasma from touching
Both fission and fusion have several advantages and disadvantages for use in producing electricity:
* Uranium-235 produces 3.7 million times the energy per unit mass as coal18
* Uranium-235 will not run out on the same timescale as fossil fuels19
* It produces no gases that directly cause global warming
* Fission produces waste radioactive actinides, which are dangerous for thousands of years
* Fission has led to disasters such as Chernobyl in 1986, which caused over 4000 deaths20
* The fuel – hydrogen – is abundant
* The radioactive waste products have half-lives hundreds of years less than those of fission
* Fusion is safer than fission, as only small amounts of products are used
* It produces no gases that directly cause global warming
* The conditions required for fission are hard to produce
* The process used to produce energy by fusion is not yet perfect – see below
Challenges Facing the Development of Fusion Power Stations
The major problem with fusion is generating and containing the conditions required for the reaction. As detailed above, a tokamak is used, this has some problems. The plasma still touches the bottom of the chamber, and where it does this; hydrogen reacts with the walls forming hydrocarbon radicals. These can form a film, which flakes away into the plasma, affecting performance21. Possible solutions include removing the film with lasers22 or using tungsten walls, which would not erode23.
A probable source of a solution is the International Tokamak Experimental Researcher, currently being built in France. It will be used as a prototype to test the reaction on the necessary levels required. Fusion should be available to produce commercial power by 2040.
Used throughout the report:
* Chemistry Review: Lise Meitner: Radiochemist, physicist and co-discoverer of nuclear fission, Gordon Woods, Volume 16 Number 1, September 2006 (Article 1); Fusion, Powering the future?, Chris Warrick, Volume 16 Number 1, September 2006; and Lithium, Chris Ennis, Volume 15 Number 31, February 2006 (Article 2)
* Salters Advanced Chemistry Chemical Ideas, George Burton et al, Heinemann Educational Publishers, Halley Court, Jordan Hill, Oxford, OX2 8EJ, ISBN 0-435-63129-9, first edition 1994, second edition 2000
1 Equation copied from page 3, Lise Meitner: Radiochemist, physicist and co-discoverer of nuclear fission; see above
2 Fig. 1 copied manually from Page 487, The exchange nature of forces, Advanced Physics, Tom Duncan, John Murray (Publishers) Ltd, 50 Albemarle Street, London, W1S 4BD, first edition 1972, ISBN 0-7195-7669-5, fifth edition 2000, reprinted 2002
3http://www.chemie.de/lexikon/e/Beta_decay, Beta Decay, (c) 1997-2008 Chemie.de Information Service
4 Equation copied from page 3, Lise Meitner: Radiochemist, physicist and co-discoverer of nuclear fission; see above
5 Table adapted from Page 20, Nuclear Reactions, Salters Advanced Chemistry Chemical Ideas; see above
6Where did the chemical elements come from?, Page 131, The Universe: A Biography, John Gribbin; published by Penguin Books Ltd, 80 Strand, London, WC2R ORL, ISBN 978-0-1410-2147-8, 2006
7Equation copied from Box 1: Nucleogenesis, Page 21, Lithium, Chris Ennis; see above
8Equation copied from Box 1: Nucleogenesis, Page 21, Lithium, Chris Ennis; see above
9 http://www.britannica.com/nobelprize/article-48278, electron capture with a Beryllium-7 nucleus, from the Encyclopaedia Britannica’s Guide to the Nobel Prizes, (c) 2008 Encyclopaedia Britannica, Inc.
10 Where do the chemical elements come from?, Page 10, Salters Advanced Chemistry Chemical Storylines, George Burton et al, Heinemann Educational Publishers, Halley Court, Jordan Hill, Oxford, OX2 8EJ, ISBN 0-435-63119-5 first edition 1994, second edition 2000
11 Fig. 2 taken from http://www.astro.bas.bg/~petrov/herter00.html, lecture notes for astronomy, Bulgarian Institute of Astronomy http://www.astro.bas.bg/
12 http://www.lancs.ac.uk/ug/bloomer/nuclearpower/theory.htm, Nuclear Fission and Nuclear Fusion, from the University of Lancaster, www.lancs.ac.uk
13 Fig. 3 copied manually from Box 2, Article 1 (see above); adapted from Chemistry Today, (c) E. Henderson, Macmillan Publishers Ltd, 1977.
14 Equation copied from Box 2, Fusion, powering the future?, Chris Warrick; see above
15 Mass of reactants and products given in proton masses in Box 2, Fusion, powering the future?, Chris Warrick; see above
16 Proton masses converted to kilograms using the mass of one proton as 1.67×10-27 kg, from Data Sheet, Page 3, AQA GCE AS Physics A Unit 1, January 2007
17 Fig. 4 taken from http://www.jet.efda.org/pages/fusion-basics/fusion3.html, Fusion Basics, (c) EFDA-JET
18 http://www.virtualnucleartourist.com/basics/reasons1.htm, a website “intended to provide you basic information about the different types of plants and their principle of operation”, (c) 2006 The Virtual Nuclear Tourist
19 http://www.abc.net.au/rn/scienceshow/stories/2007/2080110.htm, an interview with Professor Martin Sevior from the University of Melbourne by the Australian Broadcasting Corporation
20 http://www.who.int/ionizing_radiation/chernobyl/who_chernobyl_report_2006.pdf, the World Health Organisation’s report on Chernobyl
21 Chemistry Review: Fusion, powering the future?, Chris Warrick; see above
22 http://www.lasers.org.uk/paperstore/Cleaning14.pdf, Dust Removal from Next Generation Tokamaks by Laser and Flashlamp Cleaning, K. G. Watkins et al, Lasers and Laser Engineering, University of Liverpool, 2001
23 http://www.jet.efda.org/documents/articles/samm.pdf, Controlled thermonuclear fusion enters with ITER into a new era, Page 12; Ulrich Samm, EFDA-JET, 2003 | <urn:uuid:1f632206-36d6-4b25-a33c-fe4b0bd0d0e5> | 3.078125 | 2,330 | Academic Writing | Science & Tech. | 54.387573 | 95,501,424 |
domingo, 18 de septiembre de 2011
Small Galaxies Found Harboring Supermassive Black Holes
Using the Hubble Space Telescope to probe the distant universe, astronomers have found supermassive black holes growing in surprisingly small galaxies, suggest that central black holes formed at an early stage in galaxy evolution.
"It's kind of a chicken or egg problem: Which came first, the supermassive black hole or the massive galaxy? This study shows that even low-mass galaxies have supermassive black holes," said Jonathan Trump, a postdoctoral researcher at the University of California, Santa Cruz.
All massive galaxies host a central supermassive black hole, which may shine brightly as an active galactic nucleus if the black hole is pulling in nearby gas clouds. In the local universe, however, active black holes are rarely seen in small "dwarf" galaxies. The galaxies studied by Trump and his coauthors are about 10 billion light-years away, giving astronomers a view of galaxies as they appeared when the universe was less than a quarter of its current age.
"When we look 10 billion years ago, we're looking at the teenage years of the universe. So these are very small, young galaxies," Trump said.
The study, part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), used a powerful new instrument on the Hubble Space Telescope. The "slitless grism" on Hubble's WFC3 infrared camera provided detailed information about different wavelengths of light coming from the galaxies. Spectroscopy allows researchers to spread out the light from an object into its component colors or wavelengths. With Hubble's high spatial resolution, the researchers were able to get separate spectra from the center and the outer part of each galaxy. This enabled them to identify the tell-tale emissions from a central black hole.
"This is the first study that is capable of probing for the existence of small, low-luminosity black holes back in time," said coauthor Sandra Faber, University Professor of astronomy and astrophysics at UC Santa Cruz and CANDELS principal investigator. "Up to now, observations of distant galaxies have consistently reinforced the local findings--distant black holes actively accreting in big galaxies only. We now have a big puzzle: What happened to these dwarf galaxies?"
One possibility is that at least some of them are the progenitors of present-day massive galaxies like the Milky Way. "Some may remain small, and some may grow into something like the Milky Way," Trump said.
But according to Faber, both possibilities raise further questions. To become big galaxies today, the dwarf galaxies would have to grow at a rate much faster than standard models predict, she said. If they remain small, then nearby dwarf galaxies should also have central black holes. "There might be a large population of small black holes in dwarf galaxies that no one has noticed before," Faber said.
Trump noted that the distant dwarf galaxies are actively forming new stars. "Their star formation rate is about ten times that of the Milky Way," he said. "There may be a connection between that and the active galactic nuclei. When gas is available to form new stars, it's also available to feed the black hole."
In addition to the Hubble observations, the researchers obtained further evidence of active black holes in the galaxies from x-ray data acquired by NASA's Chandra X-ray Observatory. The study focused on 28 galaxies in a small patch of sky known as the Hubble Ultra Deep Field. Because each object was so small and faint, Trump combined the data from all 28 galaxies to improve the signal-to-noise ratio.
"This is a powerful technique that we can use for similar studies in the future on larger samples of objects," Trump said.
The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) is a powerful imaging survey of the distant universe being carried out with the Hubble Space Telescope. It is the largest project in the history of Hubble, with 902 assigned orbits of observing time. CANDELS makes use of the near-infrared WFC3 camera and the visible-light ACS camera.
Together, these two cameras give unprecedented panchromatic coverage of galaxies from optical wavelengths to the near-infrared. The power to look deeper into space and further back in time will enable CANDELS to construct a "cosmic movie" of galaxy evolution that follows the life histories of galaxies from infancy to the present time. This work will cap Hubble's revolutionary series of discoveries on cosmic evolution and bequeath a legacy of precious data to future generations of astronomers. CANDELS will also test the reality of cosmic dark energy by measuring the brightness of type Ia supernovae.
Provided by The Daily Galaxy - University of California, Santa Cruz
Publicado por Karla Segura Chavarría en 15:35 | <urn:uuid:dcd61a5e-3e64-45e5-ae46-931f13b04423> | 3.765625 | 1,003 | News Article | Science & Tech. | 35.144671 | 95,501,446 |
A new report published by the IUCN shows that the emblematic giraffe is facing a threatening decline.
Large marine species are favorably lost which could disrupt marine ecosystems for millions of years.
Humpback whales have made an epic return.
While the situation of pandas is improving, the same can’t be said about great apes.
In between rising temperatures and human hunters, mammoths and sabretooth tigers stood no chance.
Helicoprion is an extinct genus of shark-like, cartilaginous fish that lived from the early Permian (~290 m.y. ago) all through to the massive Permian-Triassic extinction episode (roughly 250 m.y. ago.)
For the first time in over one hundred years worldwide tiger numbers have increased, but there are still only 3,900 specimens in the wild.
Drastically reducing body size and, maybe most importantly, lifespan may have been the most important course of action evolution undertook to preserve some species, paleontologists argue.
Europe is likely to lose all its ash trees, the largest-ever survey of the species warns. Plagued by both a fungal disease known as ash-dieback and an invasive species of beetle, the emerald ash borer, the tree might be wiped clean off of the continent.
We judge our planet’s biological past by using geological evidence – fossils. Fossils are the preserved remains or traces of animals, plants, and other organisms from the remote past.
Some 360 million years ago, the oceans were teeming with big fish, some as big as a school bus. Then something terrible happened, the causes of which still escape scientists today: the Hangenberg Event. This was the last peak in a streak of mass extinctions known as the Late Devonian extinction which exterminated 97% of all marine vertebrate species. In the aftermath, it paid to be small a new study suggests. The researchers at University of Pennsylvania found that small fish dominated the ecological niches for nearly 40 million years. This tremendous rebound time is relevant today when overfishing is threatening countless large fish species. Once these disappear, it might be a very long time before we get tuna-sized fish back on our plates.
When we talk about extinction, we tend to think of it in the past-tense, or as something that just kind of happens, far removed from the activities of humankind. So let’s put things in perspective, just so we fully understand the scope of extinction.
The fact that the greatest biodiversity of large mammals we know of today is recorded in Africa is a legacy of past human activity, not climate or environmental phenomena, new study reveals. The paper theorizes at how the world today would look if Homo sapiens had never existed.
In a previous analysis, the researchers from Aarhus Univeristy, Denmark, they showed how the mass extinction of large mammals during the last Ice Age and the subsequent millennia, most notably the late-Quaternary megafauna extinction, is largely explainable by the expansion of modern humans across the world.
The world’s next massive extinction will most likely be caused not by an asteroid impact, volcano activity or alien invasion, but by us humans. A study that looked at the past and present rates of extinction found that plants and animals are going extinct 1,000 times faster than they did before humans walked on Earth’s surface. So, is it clear
Geological evidence indicate that our planet has seen five mass extinction cycles since life first appeared on the planet. While they sound like the kind of cataclysmic events that only beardy men with huge boats survive through (read that in a book once, so it must be true), they are actually an integral part of life. The cycles free up
Long before T-rex claimed the top dog spot among terrestrial predators, a vicious crocodile ancestor that walked on its hind legs was at the top of the food chain during the Triassic. The fossils of the Carnufex carolinensis, also known as the the “Carolina Butcher,” were discovered decades ago in the Pekin Formation, a geological formation in North Carolina’s Chatham County. It was only recently that researchers reanalyzed the fossils and concluded they were dealing with an all new predator that roamed the Earth several million years before dinosaurs were even around.
Life has found our blue gem planet as a welcoming host, but it hasn’t always been all fun and games. To our knowledge, life has gone through five major mass extinctions over the past couple hundred millions of years. During this time countless species and even families were wiped out in a heart beat, but geological time frame standards. When faced with overwhelming odds, nature favors those who can adapt. According to researchers at the University of Gothenburg plants have always been surprisingly resilient to these challenging times, compared to animals. That’s not to say that plants didn’t go extinct as well – sure, countless as well, but others soon filled their space at a much great pace than animals could.
The Permian was a geologic period that ended some 250 million years ago, with the largest extinction our planet has known. Geologists have now found evidence that global acidic rain accentuated or even caused the massive extinction.
In a groundbreaking analysis based on data extracted from hundreds of studies, scientists concluded that humans are on the verge of causing unprecedented and irreparable damage to the ocean environments. The patterns are clear, and extremely worrying, researchers say – but we still have time to act.
This amazing animal is the pig-nosed turtle (Carettochelys insculpta), a native to the freshwater rivers, streams and lagoons of the Northern Territory in Australia and parts of southern New Guinea. With its delicate piggy snout, webbed flippers and beautiful colors, this turtle gives to show yet again why Australia is home to some of the world’s wackiest creatures. And although it | <urn:uuid:e2ab2d10-41d2-4f59-b58d-af5d49c553c6> | 3.140625 | 1,242 | Content Listing | Science & Tech. | 41.239384 | 95,501,506 |
Physical Characterization of the Protein Molecule
Expending research effort on impure materials is a gross waste of time and talent. Yet there always exists the danger that a protein chemist, working with materials that are intrinsically hard to purify, may carry out detailed chemical studies with contaminated samples. It is the purpose of this chapter to outline some techniques by which at least the physical homogeneity of a protein may be judged. Such studies are a necessary prelude to detailed chemical investigations of proteins.
KeywordsSedimentation Velocity Physical Characterization Guanidine Hydrochloride Number Average Molecular Weight Sedimentation Coefficient
Unable to display preview. Download preview PDF. | <urn:uuid:9b3d7d0d-392f-42f2-bdbd-ecaa479f5360> | 2.515625 | 134 | Truncated | Science & Tech. | 4.605008 | 95,501,513 |
Small volcanic eruptions might eject more of an atmosphere-cooling gas into Earth’s upper atmosphere than previously thought, potentially contributing to the recent slowdown in global warming, according to a new study.
Scientists have long known that volcanoes can cool the atmosphere, mainly by means of sulfur dioxide gas that eruptions expel. Droplets of sulfuric acid that form when the gas combines with oxygen in the upper atmosphere can remain for many months, reflecting sunlight away from Earth and lowering temperatures.
However, previous research had suggested that relatively minor eruptions—those in the lower half of a scale used to rate volcano “explosivity”—do not contribute much to this cooling phenomenon.
Now, new ground-, air- and satellite measurements show that small volcanic eruptions that occurred between 2000 and 2013 have deflected almost double the amount of solar radiation previously estimated.
By knocking incoming solar energy back out into space, sulfuric acid particles from these recent eruptions could be responsible for decreasing global temperatures by 0.05 to 0.12 degrees Celsius (0.09 to 0.22 degrees Fahrenheit) since 2000, according to the new study accepted to Geophysical Research Letters, a journal of the American Geophysical Union.
These new data could help to explain why increases in global temperatures have slowed over the past 15 years, a period dubbed the ‘global warming hiatus,’ according to the study’s authors.
The warmest year on record is 1998. After that, the steep climb in global temperatures observed over the 20th century appeared to level off. Scientists previously suggested that weak solar activity or heat uptake by the oceans could be responsible for this lull in temperature increases, but only recently have they thought minor volcanic eruptions might be a factor.
Climate projections typically don’t include the effect of volcanic eruptions, as these events are nearly impossible to predict, according to Alan Robock, a climatologist at Rutgers University in New Brunswick, N.J., who was not involved in the study. Only large eruptions on the scale of the cataclysmic 1991 Mount Pinatubo eruption in the Philippines, which ejected an estimated 20 million metric tons (44 billion pounds) of sulfur, were thought to impact global climate. But according to David Ridley, an atmospheric scientist at the Massachusetts Institute of Technology in Cambridge and lead author of the new study, classic climate models weren’t adding up.
“The prediction of global temperature from the [latest] models indicated continuing strong warming post-2000, when in reality the rate of warming has slowed,” said Ridley. That meant to him that a piece of the puzzle was missing, and he found it at the intersection of two atmospheric layers, the stratosphere and the troposphere– the lowest layer of the atmosphere, where all weather takes place. Those layers meet between 10 and 15 kilometers (six to nine miles) above the Earth.
Traditionally, scientists have used satellites to measure sulfuric acid droplets and other fine, suspended particles, or aerosols, that erupting volcanoes spew into the stratosphere. But ordinary water-vapor clouds in the troposphere can foil data collection below 15 km, Ridley said. “The satellite data does a great job of monitoring the particles above 15 km, which is fine in the tropics. However, towards the poles we are missing more and more of the particles residing in the lower stratosphere that can reach down to 10 km.”
To get around this, the new study combined observations from ground-, air- and space-based instruments to better observe aerosols in the lower portion of the stratosphere.
Four lidar systems measured laser light bouncing off aerosols to estimate the particles’ stratospheric concentrations, while a balloon-borne particle counter and satellite datasets provided cross-checks on the lidar measurements. A global network of ground-based sun-photometers, called AERONET, also detected aerosols by measuring the intensity of sunlight reaching the instruments. Together, these observing systems provided a more complete picture of the total amount of aerosols in the stratosphere, according to the study authors.
Including these new observations in a simple climate model, the researchers found that volcanic eruptions reduced the incoming solar power by -0.19 ± 0.09 watts of sunlight per square meter of the Earth’s surface during the ‘global warming hiatus’, enough to lower global surface temperatures by 0.05 to 0.12 degrees Celsius (0.09 to 0.22 degrees Fahrenheit). By contrast, other studies have shown that the 1991 Mount Pinatubo eruption warded off about three to five watts per square meter at its peak, but tapered off to background levels in the years following the eruption. The shading from Pinatubo corresponded to a global temperature drop of 0.5 degrees Celsius (0.9 degrees Fahrenheit).
Robock said the new research provides evidence that there may be more aerosols in the atmosphere than previously thought. “This is part of the story about what has been driving climate change for the past 15 years,” he said. “It’s the best analysis we’ve had of the effects of a lot of small volcanic eruptions on climate.”
Ridley said he hopes the new data will make their way into climate models and help explain some of the inconsistencies that climate scientists have noted between the models and what is being observed.
Robock cautioned, however, that the ground-based AERONET instruments that the researchers used were developed to measure aerosols in the troposphere, not the stratosphere. To build the best climate models, he said, a more robust monitoring system for stratospheric aerosols will need to be developed.
The American Geophysical Union is dedicated to advancing the Earth and space sciences for the benefit of humanity through its scholarly publications, conferences, and outreach programs. AGU is a not-for-profit, professional, scientific organization representing more than 62,000 members in 144 countries. Join our conversation on Facebook, Twitter, YouTube, and other social media channels.
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“Total volcanic stratospheric aerosol optical depths and implications for global climate change”
David Ridley: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA;
S. Solomon: Department of Earth, Atmospheric, and Planetary Science,Massachusetts Institute of Technology, Cambridge, MA, USA;
J.E. Barnes: NOAA/Mauna Loa Observatory, Hilo, HI, USA;
V.D. Burlakov: V.E. Zuev Institute of Atmospheric Optics, Russian Academy of Sciences, Tomsk, Russia;
T. Deshler: Department of Atmospheric Sciences,University of Wyoming, Laramie, WY, USA;
S. I. Dolgii: V.E. Zuev Institute of Atmospheric Optics, Russian Academy of Sciences, Tomsk, Russia;
A. B. Herber: Department of Atmospheric Sciences, University of Wyoming, Laramie, WY, USA;
T. Nagai: Meteorological Research Institute, Tsukuba, Ibraraki, Japan;
R. R. Neely III: Advanced Study Program, National Center for Atmospheric Research, Boulder, CO, USA;
A. V. Nevzorov: V.E. Zuev Institute of Atmospheric Optics, Russian Academy of Sciences, Tomsk, Russia;
C. Ritter: Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Potsdam, Germany;
T. Sakai: Meteorological Research Institute, Tsukuba, Ibraraki, Japan;
B. D. Santer: Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore National Laboratory, Livermore, CA, USA;
M. Sato: The Earth Institute, Columbia University, New York, NY, USA;
A. Schmidt: School of Earth and Environment, University of Leeds, Leeds, UK;
O. Uchino: Meteorological Research Institute, Tsukuba, Ibaraki, Japan;
J. P. Vernier: Science Systems and Applications, Inc., Hampton, VA, USA and NASA Langley Research Center, Hampton, VA, USA
Contact information for the authors:
David Ridley: +1 (857) 260-0221; firstname.lastname@example.org
+1 (202) 777-7516
Kate Wheeling | American Geophysical Union
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Scientist Christopher Lavelle of the Johns Hopkins University Applied Physics Laboratory, together with a team of researchers from the University of Maryland and the National Institute of Standards and Technology, has successfully shown that boron-coated vitreous carbon foam can be used in the detection of neutrons emitted by radioactive materials -- of critical importance to homeland security. Lavelle is lead author of the paper "Demonstration of Neutron Detection Utilizing Open Cell Foam and Noble Gas Scintillation" released today in the journal Applied Physics Letters.
Detecting neutrons is key to counterterrorism activities, such as screening cargo containers, as well as other vital applications in nuclear power instrumentation, workplace safety and industry. The demand for detectors has risen dramatically over the past decade while at the same time the usual detection material, helium-3, has become harder to obtain. An advantage of the approach outlined in the paper is that boron is abundant and relatively low cost compared to helium-3. The use of a coated foam, in particular, disperses the boron evenly throughout the detector volume, increasing efficiency by filling in otherwise empty space.
Lavelle and his colleagues' work builds on a series of experiments conducted with scientists at NIST and the University of Maryland that had demonstrated that a process called noble gas scintillation can be controlled and characterized precisely enough to detect the neutrons emitted by radioactive materials. Scintillation refers to a process where energetic particles produce flashes of light when passing through certain materials, in this case xenon gas. Sensitive light detectors record the rate at which these light flashes occur to measure the presence and intensity of neutrons in the environment.
In a follow-on experiment, the research team obtained samples of "carbon foam" coated with boron carbide and placed them in xenon gas. The boron-10 isotope in the coating readily absorbs neutrons. Following neutron absorption, energetic particles are released into the gas and create flashes of light. In this experiment, researchers determined that neutrons captured deep within the coated foam produce large enough flashes to be detected by light detectors outside the foam. Previously, there had been some doubt as to whether the light flashes would actually escape foam, or if the foam would completely shadow them from the light detector.
The next steps in the series of experiments include investigating other unique detector geometries, such as multiple layers of boron-coated thin films, the use of optically transparent neutron absorbers, and finalizing a design for a potential prototype detector.
Media contact: Gina Ellrich, 443-778-7796, Gina.Ellrich@jhuapl.edu
The Applied Physics Laboratory, a not-for-profit division of The Johns Hopkins University, meets critical national challenges through the innovative application of science and technology. For more information, visit http://www.
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. Can you see out of sunglasses which shade both horizontally and vertically polarized light?
No. Such sunglasses would absorb all light and would appear black. Polarizing sunglasses are designed to absorb only horizontally polarized light; the light associated with glare. There is no reason to absorb vertically polarized light.
. Does a mirage operate under the same principle as the puddles on a road?
Not exactly. A puddle contains water, which reflects light directly. Light from the blue sky travels toward the puddle and illuminates it. As the light enters the water, with its higher refractive index, part of the light reflects. You see this light when you look at the surface of a puddle. But a mirage involves refraction (bending) of light. As light from the blue sky enters a regions of hot air near the surface, that light bends upward. You again see light from the sky, but bent upward by the air rather than being reflected upward by a surface of water. Since the two appear similar, you interpret the shimmering blue light of a mirage as coming from a pool of water. But it is just hot air.
. Does air pollution contribute to the blueness of the sky (make it bluer)? Has the sky become more blue with the advent of technology (factories, machinery, etc.)?
Yes. Pollution does tend to make the sky bluer and the sunsets redder. However, pollution also imparts colors directly by absorbing certain wavelengths of light. The orange haze that hovers over cities is often caused by nitrogen oxides, which are simply orange in color and act like pigments to make everything appear orangish. However smoke and dust certainly change the look of the sky by increasing scattering. Natural disasters are even more effective: volcanic eruptions create the most beautiful sunsets of all by tossing vast amounts of dust into the air.
. Does red or blue light bend more in glass?
Blue light almost always bends more than red light because blue light almost always travels more slowly through glass than does red light. This phenomenon is known as dispersion However, there are some glasses that exhibit anomalous dispersion, where red light travels faster and bends more than blue light. Anomalous dispersion only occurs when there is a resonant absorption of light in the glass, typically because of some impurity atoms or ions in the glass or because of some transition that occurs in the glass itself. While the resonance will only absorb light at one particular wavelength, it alters the propagation of light at nearby wavelengths. At wavelengths just shorter than the absorbed wavelength, light travels anomalously fast through the glass so that it bends less than light that is somewhat redder in color.
. Does the rainbow go all the way to the ground?
Yes, it forms an arc that extends to the ground. However, any hills or valleys may obscure its visibility or its sunlight, so you often see it truncated or in shadow.
. How come I never find the pot of gold at the base of the rainbow?
The people who invented that tale were well aware of the impossibility of reaching the rainbow itself. Knowing that the rainbow moves with you, they were free to promise anything about what lies at the base of the rainbow.
. How do oil spills/spots (i.e. in parking lots and streets) create rainbows?
A thin layer of oil on water creates interference effects, just like those seen in a thin soap film. Sunlight reflects from both the top and the bottom of the oil layer and these two reflections can interfere with one another. If the blue/green wavelengths of light interfere destructively on their way to your eye, you will see the oil layer as red. If the green/red wavelengths of light interfere destructively, you will see the oil layer as blue. How you see the oil layer depends on its thickness and the angles of the light.
. How do polarizing materials work?
The sheet polarizers that are used in sunglasses or in the demonstrations in class contain molecules that absorb electromagnetic waves of only one polarization. These molecules form long chains that interact with electromagnetic waves only when the electric fields push charge along the lengths of the molecules. In the polarizing sheets, the molecules are all oriented along the same direction so that they all absorb light of the same polarization. The other polarization of light passes through the sheets virtually unscathed. When unpolarized (randomly polarized) light enters one of these sheets, any waves that are polarized along the molecules are absorbed while any that are polarized across the molecules are permitted to pass. About half the light makes it through and that half is polarized across the molecules. If this remaining light is sent through a second polarizing sheet, turned 90° so that the molecules of the second sheet are aligned with the polarization of the light leaving the first sheet, then the remaining light will be absorbed in the second sheet and essentially no light will emerge from the pair of sheets. This arrangement, two polarizers turn 90° with respect to one another, is called "crossed polarizers". It is a useful arrangement for observing materials that rotate polarization by distorting the electric and magnetic fields. If a distorting material is placed between the two crossed polarizers, light from the first polarizer may be altered by the material and thus be able to pass through the second polarizer.
. How do shadows form?
Light from the sun travels in straight lines (apart from some wave effects called diffraction, that are unimportant in this case). As sunlight passes objects, those objects absorb or scatter the sunlight, leaving regions of space that no longer contain any electromagnetic waves. Regions of space behind the objects contain no sunlight and do not appear illuminated. We perceive those dark, unilluminated regions as shadows.
. How do window tints (for your car windows) work? Are they just polarized materials?
Some of them may be polarized materials, blocking horizontally polarized light, but most are simply absorbing materials that are embedded directly in the glass during its manufacture. Chemically tinted glass just darkens the sky be absorbing some of the light passing through the glass, regardless of polarization. It's not possible to chemically treat the glass to make it absorb only one polarization of light because that treatment would have to carefully align its molecules. In the plastic polarizing sheets, there is an alignment process (usually stretching in one direction) that lines up all the absorbing molecules. | <urn:uuid:8a04c087-39ca-4329-98f0-96a0ddea9a59> | 3.0625 | 1,317 | Q&A Forum | Science & Tech. | 48.53283 | 95,501,558 |
Hydrogen is the most frequently imaged nucleus in MRI because it is present in biological tissues in great abundance. However, any nucleus with a net nuclear spin could potentially be imaged with MRI. Such nuclei include helium-3, carbon-13, fluorine-19, oxygen-17, sodium-23, phosphorus-31 and xenon-129. 23Na, 31P and 17O are naturally abundant in the body, so can be imaged directly. Gaseous isotopes such as 3He or 129Xe must be hyperpolarized and then inhaled as their nuclear density is too low to yield a useful signal under normal conditions. 17O, 13C and 19F can be administered in sufficient quantities in liquid form (e.g. 17O-water, 13C-glucose solutions or perfluorocarbons) that hyperpolarization is not a necessity.
Multinuclear imaging is primarily a research technique at present. However, potential applications include functional imaging and imaging of organs poorly seen on 1H MRI (e.g. lungs and bones) or as alternative contrast agents. Inhaled hyperpolarized 3He can be used to image the distribution of air spaces within the lungs. Injectable solutions containing 13C or stabilized bubbles of hyperpolarized 129Xe have been studied as contrast agents for angiography and perfusion imaging. 31P can potentially provide information on bone density and structure, as well as functional imaging of the brain.Number of View: 5412 | <urn:uuid:af3f0362-3b15-496c-bb4d-fe772952c34b> | 3.03125 | 314 | Knowledge Article | Science & Tech. | 37.645736 | 95,501,577 |
Description of the Properties of Self-Assembled Quantum Dots Within the Band-Structure Model
A method for creating self-assembled dots (SAD’s) is presented in Sect. 2.6. In this chapter we shall concentrate on self-assembled dots in the shape of spherical lenses shown in Fig. 8.1 (for the description of properties of pyramidal SAD’s see ). Such a dot is formed on a narrow wetting layer of thickness t w, and modeled as a part of a sphere of height h and radius at the base s . The conduction-band edge in the material of the wetting layer and the dot lies below that in the surrounding material [114, 115]. Thus, the electrons are confined in the narrow wetting-layer quantum well due to the step in the conduction-band edge at the interface, and they are further localized in the area of the dot due to the locally increased thickness of the layer. The effective lateral potential V(r,z) that acts on the electrons confined in the wetting layer is shown in the corner of Fig. 8.1.
KeywordsAngular Momentum Lower Landau Level Numerical Diagonalization Noninteracting System Single Exciton
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A reaction that is robust and easy to perform, it is widely employed to synthesize new pharmaceuticals, biological probes, new materials and other products. But precisely how it works had been unclear since its invention at TSRI more than a decade ago.
“These new findings allow us to exert greater control of the reaction and make it faster and more efficient under the most challenging conditions,” said chemist Valery Fokin, an associate professor at TSRI, who was principal investigator for the new study. “The reaction-tracking techniques we developed here also can be applied to the study of other complex processes, both chemical and biological.”
The report, which sheds light on the reaction known as copper-catalyzed azide–alkyne cycloaddition (CuAAC), appears on April 4, 2013 in Science Experess, the advance online edition of the journal Science, and in the April 18, 2013 issue of the journal.
Classic Click Reaction
Fokin and his laboratory, and the laboratory of K. Barry Sharpless, a Nobel laureate and the W.M. Keck Professor of Chemistry at TSRI, reported the discovery of the CuAAC reaction in 2002. Danish researchers independently reported a similar reaction in the same year. The reaction involves the use of copper compounds to catalyze the linkage of two functional groups, a nitrogen-containing azide and a hydrocarbon alkyne, to make a stable five-membered heterocycle, 1,2,3-triazole. Azides and alkynes are small functional groups that can be easily introduced into a wide variety of structures using chemical or biological methods without interfering with normal biological processes.
The experimental simplicity and reliable performance of CuAAC under virtually all conditions, including in water and in the presence of oxygen, has made it a “go-to” method whenever covalent stitching of small man-made molecules or large biopolymers is needed, exemplified by protein and nucleic acid labeling, in vitro and in vivo imaging, drug synthesis and the forging of complex molecular architectures with surgical precision.
“Despite its many uses, the nature of the copper-containing reactive intermediates that are involved in the catalysis had not been well understood, in large part due to the promiscuous nature of copper, which rapidly engages in dynamic interactions with other molecules,” said Fokin.
Previous studies had hinted that in the swirl of short-lived bondings and partings that occur during a given CuAAC reaction, not one but two copper-containing catalytic units—“copper centers”—are needed to help build the new triazole structure. To confirm this, Fokin and two of his graduate students, Brady Worrell and Jamal Malik, tried to reproduce key steps of the CuAAC catalytic cycle with either one or two copper atoms available. Analysis of the reaction course by tracking the heat given off by each reaction as well as product yield indicated whether it worked efficiently. “By monitoring the reaction in real time, we showed that both copper atoms are needed and established the involvement of copper-containing intermediates that could not be isolated or directly observed,” said Worrell, who was the paper’s first author.
In a second set of experiments, Worrell, Malik and Fokin introduced a pure isotope of copper—which differs slightly in mass from the isotope blend found in natural copper—as one of the two copper centers so that they could track their respective fates during the reaction. “We hypothesized that the two copper centers would have distinct roles, but found unexpectedly that their functions during key steps in the reaction are effectively interchangeable,” said Malik.
The research reveals the popular CuAAC reaction in unprecedented detail. In addition to the fundamental insights into the chemistry of copper and its interactions with organic molecules, the techniques will lead to better understanding of many chemical and biological processes involving copper. The current study also enables development of new reactions that exploit weak interactions of copper catalysts with carbon-carbon triple bonds. In fact, based on the new findings, Fokin and his team have begun to devise new reactions in which one copper center can be replaced with a different element, to pursue complementary biocompatible and efficient techniques.
Funding for the study, “Direct Evidence of a Dinuclear Copper Intermediate in Cu(I)-Catalyzed Azide–Alkyne Cycloadditions,” was provided by grants from the National Science Foundation (CHE-0848982) and the National Institute of General Medical Sciences at the National Institutes of Health (GM-087620).
About The Scripps Research Institute
The Scripps Research Institute is one of the world's largest independent, not-for-profit organizations focusing on research in the biomedical sciences. Over the past decades, TSRI has developed a lengthy track record of major contributions to science and health, including laying the foundation for new treatments for cancer, rheumatoid arthritis, hemophilia, and other diseases. The institute employs about 3,000 people on its campuses in La Jolla, CA, and Jupiter, FL, where its renowned scientists—including three Nobel laureates—work toward their next discoveries. The institute's graduate program, which awards PhD degrees in biology and chemistry, ranks among the top ten of its kind in the nation.
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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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.
"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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