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In an article appearing in the February 14th issue of the journal Nature, Rasmus Voss of the Max Planck Institute for Extraterrestrial Physics in Germany and Gijs Nelemans of Radboud University in the Netherlands searched Chandra images for evidence of a much sought after, but as yet unobserved binary system - one that was about to go supernova. Near the position of a recently detected supernova, they discovered an object in Chandra images taken more than four years before the explosion.
Optical image of SN 2007on The supernova, known as SN 2007on, was identified as a Type Ia supernova. Astronomers generally agree that Type Ia supernovas are produced by the explosion of a white dwarf star in a binary star system. However, the exact configuration and trigger for the explosion is unclear. Is the explosion caused by a collision between two white dwarfs, or because a white dwarf became unstable by pulling too much material off a companion star?
Answering such questions is a high priority because Type Ia supernovas are major sources of iron in the Universe. Also, because of their nearly uniform intrinsic brightness, Type Ia supernova are used as important tools by scientists to study the nature of dark energy and other cosmological issues.
Chandra Image of NGC 1404 "Right now these supernovas are used as black boxes to measure distances and derive the rate of expansion of the universe," said Nelemans. "What we're trying to do is look inside the box."
If the supernova explosion is caused by material being pulled off a companion star onto the white dwarf, fusion of this material on the surface of the star should heat the star and produce a strong source of X-radiation prior to the explosion. Once the supernova explosion occurs, the white dwarf is expected to be completely destroyed and then would be undetectable in X-rays. In the merger scenario, the intensity of X-ray emission prior to the explosion is expected to be much weaker.
Chandra Image of the Fornax ClusterBased on the detection of a fairly strong X-ray source at approximately the position of SN 2007on 4 years before the explosion, Voss and Nelemans conclude that the data support the scenario where matter is pulled off a companion star. The small number of X-ray sources in the field implies that there is only a small chance of an unrelated source being so close by coincidence. Also, the X-ray source has similar properties to those expected for fusion on a white dwarf, unlike most X-ray sources in the sky.
However, in follow-up studies, Voss, Nelemans and colleagues Gijs Roelofs (Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.) and Cees Bassa (McGill University, Canada) used higher-quality optical images to better determine the supernova's position. This work, which is not yet published, shows a small, but significant difference in the measured positions of the supernova and the X-ray source, suggesting the source may not be the progenitor.
HST optical image of NGC 1404 Follow-up Chandra observations hint that the X-ray object has disappeared, but further observations are needed to finally decide whether the source was the progenitor or not.
The team is also applying this new method to other supernovas and has high hopes that they will eventually succeed in identifying the elusive cause of at least some of these explosions.
"We're very excited about opening up a new way of studying supernovas, even though we're not sure that we've seen this particular stellar bomb before it exploded," said Gijs Roelofs. "We're very confident that we'll learn a lot more about these important supernovas in the future."
Voss agrees that, even if the X-ray source is not found to be the progenitor of SN 2007on, the hunt is worth the effort.
"Finding the progenitor to one of these Type Ia supernovas is a great chase in astronomy right now," he said. "These supernovas are great tools for studying dark energy, but if we knew more about how they form they might become even better tools."
Rasmus Voss receives support from the Excellence Cluster Universe in Garching, Germany. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass
Megan Watzke | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Life Sciences
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Artist’s rendering of Tingmiatornis arctica, the new prehistoric bird species discovered by scientists at the University of Rochester. Credit: Artist rendering by Michael Osadciw/University of Rochester A team of geologists at the University of Rochester has discovered a new species of bird in the Canadian Arctic. At approximately 90 million years old, the bird fossils are among the oldest avian records found in the northernmost latitude, and offer further evidence of an intense warming event during the late Cretaceous period. ”The bird would have been a cross between a large seagull and a diving bird like a cormorant, but likely had teeth,” says John Tarduno, professor and chair of the Department of Earth and Environmental Sciences at the University and leader of the expedition.
Tarduno and his team, which included both undergraduate and graduate students, named the bird Tingmiatornis arctica; ”Tingmiat” means ”those that fly” in the Inuktitut language spoken in the central and eastern Canadian Arctic (Nunavut territory).
Their findings, published in Scientific Reports, add to previous fossil records Tarduno uncovered from the same geological time period and location in previous expeditions. Taken together, these fossils paint a clearer picture of an ecosystem that would have existed in the Canadian Arctic during the Cretaceous period’s Turonian age, which lasted from approximately 93.9 to 89.8 million years ago.
”These fossils allow us to flesh out the community and add to our understanding of the community’s composition and how it differed from other places in the world,” says Donald Brinkman, vertebrate paleontologist and director of preservation and research at the Royal Tyrrell Museum in Alberta, Canada.The video will load shortlyBuilding historic climate records further helps scientists determine the effects of climate on various communities, ecosystems, and the distribution of species and could help predict the effects of future climatic events.
”Before our fossil, people were suggesting that it was warm, but you still would have had seasonal ice,” Tarduno says. ”We’re suggesting that’s not even the case, and that it’s one of these hyper-warm intervals because the bird’s food sources and the whole part of the ecosystem could not have survived in ice.”
From the fossil and sediment records, Tarduno and his team were able to conjecture that the bird’s environment in the Canadian Arctic during the Turonian age would have been characterized by volcanic activity, a calm freshwater bay, temperatures comparable to those in northern Florida today, and creatures such as turtles, large freshwater fish, and champsosaurs—now-extinct, crocodile-like reptiles.
”The fossils tell us what that world could look like, a world without ice at the arctic,” says Richard Bono, a PhD candidate in earth and environmental sciences at the University and a member of Tarduno’s expedition. ”It would have looked very different than today where you have tundra and fewer animals.” An artist’s conception of the bird’s possible environment 90 million years ago, characterized by volcanic activity, a freshwater bay, turtles, fish, and champsosaurs. Credit: University of Rochester illustration / Michael Osadciw The Tingmiatornis arctica fossils were found above basalt lava fields, created from a series of volcanic eruptions. Scientists believe volcanoes pumped carbon dioxide into the Earth’s atmosphere, causing a greenhouse effect and a period of extraordinary polar heat. This created an ecosystem allowing large birds, including Tingmiatornis arctica, to thrive.
Tarduno’s team unearthed three bird bones: part of the ulna and portions of the humerus, which, in birds, are located in the wings. From the bone features, as well as its thickness and proportions, the team’s paleontologist, Julia Clarke of the University of Texas, was able to determine the evolutionary relationships of the new birds as well as characteristics that indicate whether it likely was able to fly or dive.
”These birds are comparatively close cousins of all living birds and they comprise some of the oldest records of fossil birds from North America,” Clarke says. ”Details of the upper arm bones tell us about how features of the flightstroke seen in living species came to be.”
Previous fossil discoveries indicate the presence of carnivorous fish such as the 0.3-0.6 meter-long bowfin. Birds feeding on these fish would need to be larger-sized and have teeth, offering additional clues to Tingmiatornis arctica’s characteristics. Tingmiatornis arctica bird fossil. Credit: University of Rochester photo / John Tarduno Physiological factors, such as a rapid growth and maturation rate, might explain how this line of bird was able to survive the Cretaceous-Paleogene mass extinction event that occurred approximately 66 million years ago and eliminated approximately three-quarters of the plant and animal species on Earth.
These physiological characteristics are still conjecture, Tarduno emphasizes, but he says the bird’s environment gives clear indications as to why the bird fossils were found in this location.
”It’s there because everything is right,” Tarduno says. ”The food supply was there, there was a freshwater environment, and the climate became so warm that all of the background ecological factors were established to make it a great place.”
Explore further:Fossils of early tetrapods unearthed in Scotland
Journal reference:Scientific Reports
Provided by:University of Rochester | <urn:uuid:babbda3a-428b-4264-8ba0-d71e728c621f> | 3.796875 | 1,200 | News Article | Science & Tech. | 23.601018 | 95,483,139 |
Allele elimination recalculated: nested subset analyses for molecular biogeographical data
Post‐glacial colonization of species from low‐latitude refugia to high latitudes, or from lower to higher elevations, often involves repeated founder effects due to stepwise colonization. This may cause repeated population bottlenecks and the subsequent loss of alleles. Regression analyses have traditionally been used to analyse the correlation between the mean numbers of alleles and geographical distances from refugia. Here, we describe and evaluate the performance of nested subset analyses for detecting allele elimination.
Genetic data sets from five butterfly and one beetle species were reanalysed using regression and nested subset analyses.
The data sets analysed here showed both congruent and divergent results under regression and nested subset analyses. Some data sets did not feature a significant correlation between the mean number of alleles and the colonization trajectory, but did show significant nested structure. Others showed the opposite effects. Using allele frequencies from the same data sets, we did not obtain significant patterns of nestedness.
Our results indicate that classical regression analyses are not always a suitable tool for analysing allele elimination, and nestedness analyses are much more meaningful. Local natural selection can alter allele frequencies, thereby erasing biogeographical patterns that have evolved as a result of the stochastic processes involved in colonization. Thus, an appropriate means of documenting allele elimination sensu Reinig is the joint application of nested subset and regression analyses based on presence/absence and abundance data for genetic diversity.
No Supplementary Data
No Article Media
Document Type: Research Article
Publication date: 01 April 2013 | <urn:uuid:2dfd5ea8-61f6-4ad4-a526-2140d8970514> | 2.53125 | 332 | Academic Writing | Science & Tech. | -5.503744 | 95,483,143 |
The study, which appears in the advance online edition of the journal Molecular and Cellular Biology, indicates that two proteins, named Timeless and Tipin, form a complex that regulates the rate at which DNA is replicated after exposure to ultraviolet radiation.
Ultraviolet radiation in sunlight damages the DNA in skin cells. If left unrepaired by the cell, this damage can turn into mutations that lead to cancer. Before cells divide, they must replicate, or copy, their DNA to form new daughter cells. If damage in the DNA is discovered even after the cell has given a "go-ahead" to replicate its DNA, the Timeless/Tipin complex sends a signal throughout the nucleus of the cell to slow the rate of replication. This slowdown may give the cell additional time to repair its DNA and potentially save itself from becoming cancerous or from dying in response to ultraviolet radiation.
"What we discovered here was that the cell can send out an additional SOS and slow DNA replication even after it has begun," said Dr. William Kaufmann, a professor of pathology and laboratory medicine and a member of the UNC Lineberger Comprehensive Cancer Center and Center for Environmental Health and Susceptibility.
"We've known for 25 years that a cell can stop DNA replication from even starting when it detects damage in its own DNA – this gives the DNA repair mechanisms in the cell the time to find and repair the damage," he said.
Using an innovative new technique to visualize the replication of DNA strands exposed to ultraviolet radiation, Kaufmann and his co-authors noted a slowdown in DNA replication when Timeless and Tipin were present in the cell. Building blocks for DNA were labeled with fluorescent molecules so that tracks of newly synthesized DNA could be observed under the microscope and their lengths measured.
Though the study specifically examined only the Timless/Tipin response to ultraviolet radiation, Kaufmann speculates that this response may be relevant to other types of DNA damage as well – including those used as treatments for cancer.
"This protective response may make some cells more resistant to certain types of cancer therapies which work by inducing the cancer cell to die. If the cell, even if it is a cancer cell, is given this additional time to recover from treatment, it may be able to survive it, much to the detriment of the patient." Kaufmann said.
Ultraviolet radiation in sunlight causes at least one million cases of skin cancer in the U.S. annually and greater than fifty thousand cases of melanoma.
Leslie Lang | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Materials Sciences
20.07.2018 | Physics and Astronomy
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Astronomers have used a radio telescope in outback Western Australia to see the halo of a nearby starburst galaxy in unprecedented detail.
A starburst galaxy is a galaxy experiencing a period of intense star formation and this one, known as NGC 253 or the Sculptor Galaxy, is approximately 11.5 million light-years from Earth.
"The Sculptor Galaxy is currently forming stars at a rate of five solar masses each year, which is a many times faster than our own Milky Way," said lead researcher Dr Anna Kapinska, from The University of Western Australia and the International Centre for Radio Astronomy Research (ICRAR) in Perth.
"This galaxy is famous because it's beautiful and very close to us, and because of what's happening inside it--it's quite extraordinary."
The Sculptor Galaxy has an enormous halo of gas, dust and stars, which had not been observed before at frequencies below 300 MHz. The halo originates from galactic "fountains" caused by star formation in the disk and a super-wind coming from the galaxy's core.
"We're very fortunate to have such a great example of a starburst galaxy in our own cosmic backyard--it's like having a galaxy-sized laboratory on hand to conduct experiments and test our theories," said Dr Kapinska.
The study used data from the 'GaLactic and Extragalactic All-sky MWA', or 'GLEAM' survey, which was observed by the Murchison Widefield Array (MWA) radio telescope located in remote Western Australia.
"With the GLEAM survey we were able, for the first time, to see this galaxy in its full glory with unprecedented sensitivity at low radio frequencies," said Dr Kapinska.
"It's remarkable how easily the MWA detected the diffuse halo, we managed it with just an hour of observing as the galaxy passed overhead," she said.
"We could see radio emission from electrons accelerated by supernova explosions spiralling in magnetic fields, and absorption by dense electron-ion plasma clouds --it's absolutely fascinating."
The MWA is a precursor to the Square Kilometre Array (SKA) radio telescope, part of which will be built in Western Australia in the next decade.
Co-author Professor Lister Staveley-Smith, from ICRAR and the ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), said the SKA will be the largest radio telescope in the world and will be capable of discovering many new star-forming galaxies when it comes online.
"But before we're ready to conduct a large-scale survey of star-forming and starburst galaxies with the SKA we need to know as much as possible about these galaxies and what triggers their extreme rate of star formation," he said.
"By getting to the bottom of what's causing this galaxy to produce so many stars, we can better understand how other galaxies form, grow and change over time throughout the Universe."
The MWA: The Murchison Widefield Array (MWA) is a low frequency radio telescope located at the Murchison Radio-astronomy Observatory in Western Australia's Mid West. The MWA observes radio waves with frequencies between 70 and 320 MHz and was the first of the three Square Kilometre Array (SKA) precursors to be completed.
The SKA: Co-located primarily in South Africa and Western Australia, the SKA will be a collection of hundreds of thousands of radio antennas with a combined collecting area equivalent to approximately one million square metres, or one square kilometre.
ICRAR: The International Centre for Radio Astronomy Research, or ICRAR, is a joint venture between Curtin University and The University of Western Australia with support and funding from the State Government of Western Australia.
CAASTRO: CAASTRO is a collaboration of The University of Sydney, The Australian National University, The University of Melbourne, Swinburne University of Technology, The University of Queensland, The University of Western Australia and Curtin University. It is funded under the Australian Research Council (ARC) Centre of Excellence program, with additional funding from the seven participating universities and from the NSW State Government's Science Leveraging Fund.
High-resolution images (plus captions and credits) are available from http://www.
Dr Anna Kapinska (ICRAR-UWA, CAASTRO)
Ph: +61 474 476 790 E: Anna.Kapinska@icrar.org
Dr Lister Staveley-Smith (ICRAR-UWA, CAASTRO)
Ph: +61 425 212 592 E: Lister.Staveley-Smith@icrar.org
Pete Wheeler (Media Contact, ICRAR)
Ph: +61 423 982 018 E: Pete.Wheeler@icrar.org
Pete Wheeler | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
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World’s Largest Coral Gene Database
News May 25, 2016
Coral reefs – stunning, critical habitats for an enormous array of prized fish and other species – have survived five major extinction events over the last 250 million years.
Now, an international team of scientists led by Rutgers faculty has conducted the world’s most comprehensive analysis of coral genes, focusing on how their evolution has allowed corals to interact with and adapt to the environment. A second study led by Rutgers researchers with colleagues at the University of Hawaii shows – for the first time – how stony corals create their hard skeletons, using proteins as key ingredients.
“There are a few key genes in corals that allow them to build this house that laid down the foundation for many, many thousands of years of corals,” said Debashish Bhattacharya, a professor in the Department of Ecology, Evolution and Natural Resources in the School of Environmental and Biological Sciences at Rutgers. “It couldn’t be any more fundamental to ocean ecosystems.”
“I think one of the more interesting aspects of these data will be to understand which coral species may become winners or losers in the face of anthropogenic climate change – what makes them tougher and what makes them susceptible to changes in temperature, changes in ocean acidification,” said Paul Falkowski, a professor who leads the Environmental Biophysics and Molecular Ecology Laboratory at Rutgers.
The coral gene database study, led by Bhattacharya and Falkowski, was published today in the journal eLife. The study stems from an international coral genomics symposium and workshop held at Rutgers in February 2014 that was funded by the National Science Foundation. The stony coral study was published in the Proceedings of the Royal Society B: Biological Sciences last month.
Nearly all corals are colonial organisms that consist of as many as hundreds of thousands of animals called polyps. Types of corals include stony, shallow-water species that build reefs, soft corals and deep-water corals that live in dark cold waters, according to the National Oceanic and Atmospheric Administration.
Corals face four major threats from humans: Destruction of reefs by grenades and poison used to kill fish for food; nutrient pollution, usually from sewage or agricultural runoff, that overstimulates harmful algae; increased heat in the upper ocean, which causes most coral bleaching that can kill reefs; and acidification of the ocean, according to Falkowski.
“Corals are the most diverse marine ecosystems on the planet,” he said. “But their value to marine ecosystems – and to our own use of marine resources – is very underappreciated.”
Recent aerial and underwater surveys have found that 93 percent of the Great Barrier Reef off Queensland in Australia has endured very severe, moderate or at least some coral bleaching this year, according to the ARC Centre of Excellence for Coral Reef Studies in Australia. The reef, a world-renowned tourist attraction, is about 1,430 miles long.
Elevated sea temperatures from global warming can cause corals to expel tiny, colorful algae, according to the center. Corals turn translucent and white when they lose the algae. Mildly bleached corals can recover if the temperature drops and algae can recolonize them. If not, corals may die.
At Rutgers two years ago, leaders in the field of coral biology and genomics met to plan an analysis of 20 coral genomic datasets. The goal was to provide a comprehensive understanding of coral evolution since the organisms appeared on Earth 525 million years ago. The coral database, which includes corals in tropical waters, has been posted on the comparative.reefgenomics.org website to foster growth in this important area of research.
The eLife study’s major advances include explaining the origin and evolution of the unique genes involved in the creation of hard skeletons by corals. The study also serves as a novel toolkit compared with the genes of humans, shellfish and other animals with hard skeletons.
Bhattacharya and coauthors found dozens of genes that allow corals to coordinate their response to changes in temperature, light and pH (acidity vs. alkalinity) and deal with stress triggered by the algae that live with them and exposure to high levels of light.
Surprisingly, some of these stress-related genes are of bacterial origin and were acquired to help corals survive. An intriguing theory that arose from the study is that the vast genetic repertoire of corals may help them adapt to changing ocean conditions.
The study in the Proceedings of the Royal Society B: Biological Sciences – led by former Rutgers Department of Marine and Coastal Sciences post-doctoral fellow Tali Mass – explains how stony corals make their hard, calcium carbonate skeletons. It also explains how this process might be affected as the oceans become more acidic due to climate change. Acidity increases as oceans are exposed to higher concentrations of carbon dioxide, the main greenhouse gas and cause of climate change, in the atmosphere.
“The aragonite (hard skeleton) is not just minerals,” Bhattacharya said. “The proteins are very important for giving it shape and making it stable.”
Falkowski said the study serves as a model for understanding how we can regenerate bone. “There are amazing parallels between the production of the skeleton of coral and production of bone,” he said.
Analytical Tool Predicts Disease-Causing GenesNews
Predicting genes that can cause disease due to the production of truncated or altered proteins that take on a new or different function, rather than those that lose their function, is now possible thanks to an international team of researchers that has developed a new analytical tool to effectively and efficiently predict such candidate genes.
Single Gene Change in Gut Bacteria Alters Host MetabolismNews
Scientists have found that deleting a single gene in a particular strain of gut bacteria causes changes in metabolism and reduced weight gain in mice. The research provides an important step towards understanding how the microbiome – the bacteria that live in our body – affects metabolism.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:a703ed3e-e4c2-47c3-8180-fd551811f78b> | 3.65625 | 1,334 | News Article | Science & Tech. | 27.156688 | 95,483,165 |
Climate change is likely to have significant effects on the hydrology. The Ganges-Brahmaputra river basin is one of the most vulnerable areas in the world as it is subject to the combined effects of glacier melt, extreme monsoon rainfall and sea level rise. To what extent climate change will impact river flow in the Brahmaputra basin is yet unclear, as climate model studies show ambiguous results. In this study we investigate the effect of climate change on both low and high flows of the lower Brahmaputra. We apply a novel method of discharge-weighted ensemble modeling using model outputs from a global hydrological models forced with 12 different global climate models (GCMs). Our analysis shows that only a limited number of GCMs are required to reconstruct observed discharge. Based on the GCM outputs and long-term records of observed flow at Bahadurabad station, our method results in a multi-model weighted ensemble of transient stream flow for the period 1961-2100. Using the constructed transients, we subsequently project future trends in low and high river flow. The analysis shows that extreme low flow conditions are likely to occur less frequent in the future. However a very strong increase in peak flows is projected, which may, in combination with projected sea level change, have devastating effects for Bangladesh. The methods presented in this study are more widely applicable, in that existing multi-model streamflow simulations from global hydrological models can be weighted against observed streamflow data to assess at first order the effects of climate change for specific river basins.
Mendeley saves you time finding and organizing research
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A View from Emerging Technology from the arXiv
Why Black Holes May Constitute All Dark Matter
No Earth-based experiments have spotted any sign of dark matter-type particles. Perhaps that’s because dark matter is an entirely different kind of thing
Dark matter is the mysterious stuff that cosmologists believe fills our Universe. The evidence for its existence is that there is not enough visible mass to hold galaxies together. But since galaxies manifestly do not fly apart, there must be some invisible stuff, some missing mass, that generates the gravitational forces holding them together.
But there’s a problem with this idea. Two of them actually. First, physicists’ best guess at the laws of physics give a good description of all of the particles they’ve discovered so far and a few they expect to discover soon. The trouble is that none of these particles have the right kind of properties to be dark matter ie electrically neutral, long-lived and slow moving. But none of the known or reasonably hypothesised particles fits the bill. To make room for a dark matter particle, the laws of physics have to be changed in ways that many theorists feel uncomfortable with.
Second, despite a decade spent searching for dark matter with experiments costing tens of millions of dollars, nobody has laid eyes on the stuff. Most physicists think these experiments have found nothing: zip, zilch, zero.
It’s hard to escape the conclusion that some other explanation for the missing mass is needed.
Enter Paul Frampton at the University of North Carolina and a few buddies. Frampton’s suggestion is that the missing mass is made up of black holes that are too small to see directly but too big to have evaporated away due to Hawking radiation.
But this idea is more than another wild guess. Frampton and pals have an interesting argument based on entropy to back up their claim. It goes like this.
First they determine what the maximum entropy of the Universe could be by imaging that the entire visible universe were a giant black hole. The answer turns out to be 10^123, a very big number. So that’s the upper limit on what the entropy can be.
Next, they work out a lower limit by adding together the entropy in all the known black holes in the universe. They work this out by assuming that there’s a giant black hole at the centre of every galaxy, a view that is increasingly commonly held by astrophysicists.
That gives the number 10^103, many orders of magnitude lower.
This a great deal of entropy, to be sure, but Frampton and co so it is unlikely to be the major contributor in our universe. “Each supermassive black hole is about the size of our solar system or smaller and it is intuitively unlikely that essentially all of the entropy is so concentrated,” he says. So something else must be generating entropy somewhere.
It can’t be visible matter since conventional calculations indicate that its entropy adds up to only 10^88. What’s left is the entropy of the missing dark mass.
What type of black holes could be responsible for this? It turns out that any black hole bigger than 10^6 solar masses would cause nearby matter to spiral into it, preventing galaxies from forming. Anything smaller than 10^-8 solar masses would have evaporated.
So the conclusion is that dark matter is made up of black holes with a mass of between 10^6 and 10^-8 solar masses.
But there’s a problem with this idea too. How could these black holes have formed in such large numbers early in the Universe. Something must have caused matter to clump together at this scale to form the black holes. But there is nothing to indicate how this might have happened in the present theory of inflation, which describes how the early Universe grew.
hat’s easily solved say Frampton and co: there must have been two periods of inflation. The first led to the large scale structure of the Universe that we see and has been measured by spacecraft such as WMAP. The second led t the clumping that created large numbers of medium-sized primordial black holes.
That’s an explanation that is a little easier to stomach than one in which the laws of physics must change to create new dark matter particles. But only just.
However Frampton’s ideas can be better tested by looking for evidence of these primordial black holes, which should cause microlensing events: ie their gravity should focus the light from stars behind them as seen from Earth.
Those kinds of measurements are getting easier to do so it should be possible to acept or reject Frampton’s ideas in the not too distant future.
arxiv.org/abs/1003.3356: Black Holes Constitute All Dark Matter
arxiv.org/abs/1001.2308: Primordial Black Holes As All Dark Matter
Couldn't make it to EmTech Next to meet experts in AI, Robotics and the Economy?Go behind the scenes and check out our video | <urn:uuid:509778c7-600e-451a-a575-bd17296b3f2c> | 3.375 | 1,052 | News Article | Science & Tech. | 55.062842 | 95,483,183 |
Introduced and invasive plant species have contributed to habitat degradation and the loss of suitable native forest bird habitat across Hawai’i. Invasive species are non-native or alien species (plant, animal, or microbe) transported by humans to a location outside its native range and whose introduction does or is likely to cause economic or environmental harm and/or harm to human health (U.S. Presidential Executive Order 13112). Non-native species make their way to Hawai’i every day through imported plants, people, and ships.
Invasive plants create dense growths and crowd out native plants, which decreases biological diversity. Additionally, many of these invasive plants use more water than native plants, thus decreasing the availability of water within the forest and the watershed. Most native birds will not feed off of non-native plants as they are not adapted to recognize them as a food source. There are organizations on island like the Maui Invasive Species Committee whose mission is to prevent invasive species from becoming established and limiting the most harmful ones.
MFBRP works in some of the most pristine areas of Maui, where much of the forest is native. Some of the top invasive plants of concern in The Nature Conservancy’s (TNC) Waikamoi Preserve include: Gorse (Ulex europaeus), Kahili Ginger (Hedychium gardnerianum), Blackberry (Rubus argutus), Pines (Pinusspp.), Blackwood Acacia (Acacia melanoylon), Tropical Ash (Fraxinus uhdei), and Eucalyptus (Eucalyptus spp.). At Nakula Natural Area Reserve, where MFBRP also works on forest restoration, there are many invasive plants such as Kikuyu grass (Pennisetum clandestinum), Velvet grass (Holcus lanatus), and Tree Poppy (Bocconia frutescens). We are also on the lookout for Koster’s Curse (Clidemia hirta) and Australian Tree Fern (Cyathea cooperi). Introduction of non-native plants to these areas could be caused by humans, pigs, or bird dispersal.
To prevent the introduction and spread of weed species, MFBRP takes precautions by making sure all gear is clean before entering any field sites- this includes cleaning clothing, backpacks, tents, boots, and raingear. Before each field trip, all gear is thoroughly inspected and cleaned. All dirt, seeds, and insects are carefully removed. MFBRP uses GPS to mark locations of non-native plants and may remove them to limit and prevent their spread. In Waikamoi, TNC is also notified of invasive plants as they have an intensive invasive species management program. Control efforts are focused on ecosystem modifying species and incipient populations that can be controlled through minimal effort. Because invasive plants are often very difficult to control once they have entered an area, prevention of new introductions is crucial.
Rapid ʻŌhiʻa Death is a fairly new fungal disease that is currently killing native ʻōhiʻa (Metrosideros polymorpha) trees. This fungal disease was first found on Hawaii Island (2015) and most recently on Kauai (2018). Rapid ʻŌhiʻa Death has killed hundreds of thousands of ʻōhiʻa on Hawaii island with the potential to kill ʻōhiʻa trees statewide. It is important to prevent the spread of this disease to other islands and other forests on Hawai’i Island. Please read more about this alarming invasive disease here.
You can do your part by becoming aware of invasive plants (Hawai’i State-listed Noxious Weeds) and making sure not to spread them. Clean your camping and hiking gear and do not support more introductions. For more reading go to: What You Can Do to Help Stop the Silent Invasion. | <urn:uuid:aceafa7c-810b-43bd-9b0d-e3855dd4fc34> | 3.65625 | 820 | Knowledge Article | Science & Tech. | 34.018548 | 95,483,248 |
Draft REST cheat sheet
Last revision (mm/dd/yy): 05/26/2018
DRAFT Cheat sheet - WORK IN PROGRESS
REST (or REpresentational State Transfer) is an architectural style first described in Roy Fielding's Ph.D. dissertation on Architectural Styles and the Design of Network-based Software Architectures. It evolved as Fielding wrote the HTTP/1.1 and URI specs and has been proven to be well-suited for developing distributed hypermedia applications. While REST is more widely applicable, it is most commonly used within the context of communicating with services via HTTP.
The key abstraction of information in REST is a resource. A REST API resource is identified by a URI, usually a HTTP URL. REST components use connectors to perform actions on a resource by using a representation to capture the current or intended state of the resource and transferring that representation. The primary connector types are client and server, secondary connectors include cache, resolver and tunnel.
REST APIs are stateless. Stateful APIs do not adhere to the REST architectural style. State in the REST acronym refers to the state of the resource which the API accesses, not the state of a session within which the API is called. While there may be good reasons for building a stateful API, it is important to realize that managing sessions is complex and difficult to do securely. Stateful services are out of scope of this Cheat Sheet. Passing state from client to backend, while making the service technically stateless, is an anti-pattern that should also be avoided as it is prone to replay and impersonation attacks.
In order to implement flows with REST APIs, resources are typically created, read, updated and deleted. For example, an ecommerce site may offer methods to create an empty shopping cart, to add items to the cart and to check out the cart. Each of these REST calls is stateless and the endpoint should check whether the caller is authorized to perform the requested operation.
Secure REST services must only provide HTTPS endpoints. This protects authentication credentials in transit, for example passwords, API keys or JSON Web Tokens. It also allows clients to authenticate the service and guarantees integrity of the transmitted data.
See the Transport Layer Protection Cheat Sheet for additional information.
Consider the use of mutually authenticated client-side certificates to provide additional protection for highly privileged web services.
Non-public REST services must perform access control at each API endpoint. Web services in monolithic applications implement this by means of user authentication, authorisation logic and session management. This has several drawbacks for modern architectures which compose multiple micro services following the RESTful style.
There seems to be a convergence towards using JSON Web Tokens (JWT) as the format for security tokens. JWTs are JSON data structures containing a set of claims that can be used for access control decisions. A cryptographic signature or message authentication code (MAC) can be used to protect the integrity of the JWT.
If MACs are used for integrity protection, every service that is able to validate JWTs can also create new JWTs using the same key. This means that all services using the same key have to mutually trust each other. Another consequence of this is that a compromise of any service also compromises all other services sharing the same key. See https://tools.ietf.org/html/rfc7515#section-10.5 for additional information.
The relying party or token consumer validates a JWT by verifying its integrity and claims contained.
Some claims have been standardised and should be present in JWT used for access controls. At least the following of the standard claims should be verified:
Public REST services without access control run the risk of being farmed leading to excessive bills for bandwidth or compute cycles. API keys can be used to mitigate this risk. They are also often used by organisation to monetize APIs; instead of blocking high-frequency calls, clients are given access in accordance to a purchased access plan.
API keys can reduce the impact of denial-of-service attacks. However, when they are issued to third-party clients, they are relatively easy to compromise.
Restrict HTTP methods
In Java EE in particular, this can be difficult to implement properly. See Bypassing Web Authentication and Authorization with HTTP Verb Tampering for an explanation of this common misconfiguration.
Validate content types
A REST request or response body should match the intended content type in the header. Otherwise this could cause misinterpretation at the consumer/producer side and lead to code injection/execution.
Validate request content types
Send safe response content types
It is common for REST services to allow multiple response types (e.g. "application/xml" or "application/json", and the client specifies the preferred order of response types by the Accept header in the request.
To make sure the content of a given resources is interpreted correctly by the browser, the server should always send the Content-Type header with the correct Content-Type, and preferably the Content-Type header should include a charset. The server should also send an X-Content-Type-Options: nosniff to make sure the browser does not try to detect a different Content-Type than what is actually sent (can lead to XSS).
Additionally the client should send an X-Frame-Options: deny to protect against drag'n drop clickjacking attacks in older browsers.
Sensitive information in HTTP requests
RESTful web services should be careful to prevent leaking credentials. Passwords, security tokens, and API keys should not appear in the URL, as this can be captured in web server logs, which makes them intrinsically valuable.
HTTP Return Code
HTTP defines status code . When designing REST API, don't just use 200 for success or 404 for error.
Here are some guideline to consider for each REST API status return code. Proper error handle may help to validate the incoming requests and better identify the potential security risks.
OWASP Cheat Sheets Project Homepage
Authors and primary editors
Erlend Oftedal - email@example.com | <urn:uuid:09e6a7c6-c405-4c77-b302-c664c939126d> | 2.640625 | 1,268 | Documentation | Software Dev. | 39.417722 | 95,483,271 |
Exploring the Movement of Matter in Ecosystems (Day 2)
Lesson 22 of 28
Objective: SWBAT describe the movement of matter among plants, animals, and decomposers.
Inquiry Based Instructional Model
To intertwine scientific knowledge and practices and to empower students to learn through exploration, it is essential for scientific inquiry to be embedded in science education. While there are many types of inquiry-based models, one model that I've grown to appreciate and use is called the FERA Learning Cycle, developed by the National Science Resources Center (NSRC):
A framework for implementation can be found here.
I absolutely love how the Center for Inquiry Science at the Institute for Systems Biology explains that this is "not a locked-step method" but "rather a cyclical process," meaning that some lessons may start off at the focus phase while others may begin at the explore phase.
Finally, an amazing article found at Edudemic.com, How Inquiry-Based Learning Works with STEM, very clearly outlines how inquiry based learning "paves the way for effective learning in science" and supports College and Career Readiness, particularly in the area of STEM career choices.
In this unit, students will first develop an understanding of the biotic and abiotic factors within ecosystems, the characteristics and classification of living organisms, and how plants and animals obtain and use energy to fulfill their needs.
Then, students will delve deeper into the NGSS standards by examining the interdependent relationships within an ecosystem by studying movement of matter between producers, consumers, and decomposers by creating models of food chains and food webs.
At the end of this unit, students will study ways that individual communities can use science ideas to protect the Earth's resources and environment.
Summary of Lesson
Today, I will open the lesson by showing students a video on the six essential nutrients for proper growth in animals. Students will then explore even more ways that matter flows through an ecosystem. At the end of the lesson, students will reflect and apply their new understanding of the movement of matter by adding to their written summaries from yesterday.
Next Generation Science Standards
This lesson will support the following NGSS Standard(s):
5-LS2-1. Develop a model to describe the movement of matter among plants, animals, decomposers, and the environment.
5-ESS3-1. Obtain and combine information about ways individual communities use science ideas to protect the Earth’s resources and environment.
Scientific & Engineering Practices
For this lesson, students are engaged in the following Science & Engineering Practice:
Science & Engineering Practice 6: Constructing Explanations and Designing Solutions
Using observations and evidence, students construct an explanation to describe how matter moves amongst plants, animals, and decomposers.
To relate ideas across disciplinary content, during this lesson I focus on the following Crosscutting Concept:
Crosscutting Concept 5: Energy and Matter
Students describe how matter flows and cycles through an ecosystem using the food chain as a model. Students also beginning learning about the conservation of matter and how the matter on Earth remains constant.
Disciplinary Core Ideas
In addition, this lesson also aligns with the following Disciplinary Core Ideas:
PS3.D: Energy in Chemical Processes and Everyday Life
The energy released [from] food was once energy from the sun that was captured by plants in the chemical process that forms plant matter (from air and water). (5-PS3-1)
LS1.C: Organization for Matter and Energy Flow in Organisms
Food provides animals with the materials they need for body repair and growth and the energy they need to maintain body warmth and for motion. (secondary to 5-PS3-1)
Plants acquire their material for growth chiefly from air and water. (5-LS1-1)
LS2.A: Interdependent Relationships in Ecosystems
The food of almost any kind of animal can be §traced back to plants. Organisms are related in food webs in which some animals eat plants for food and other animals eat the animals that eat plants. Some organisms, such as fungi and bacteria, break down dead organisms (both plants or plants parts and animals) and therefore operate as “decomposers.” Decomposition eventually restores (recycles) some materials back to the soil. Organisms can survive only in environments in which their particular needs are met. A healthy ecosystem is one in which multiple species of different types are each able to meet their needs in a relatively stable web of life. Newly introduced species can damage the balance of an ecosystem. (5-LS2-1)
LS2.B: Cycles of Matter and Energy Transfer in Ecosystems
Matter cycles between the air and soil and among plants, animals, and microbes as these organisms live and die. Organisms obtain gases, and water, from the environment, and release waste matter (gas, liquid, or solid) back into the environment. (5-LS2-1)
Choosing Science Teams
With science, it is often difficult to find a balance between providing students with as many hands-on experiences as possible, having plenty of science materials, and offering students a collaborative setting to solve problems. Any time groups have four or more students, the opportunities for individual students to speak and take part in the exploration process decreases. With groups of two, I often struggle to find enough science materials to go around. So this year, I chose to place students in teams of three! Picking science teams is always easy as I already have students placed in desk groups based upon behavior, abilities, and communication skills. Each desk group has about six kids, so I simply divide this larger group in half.
Gathering Supplies & Assigning Roles
To encourage a smooth running classroom, I ask students to decide who is a 1, 2, or 3 in their groups of three students (without talking). In no time, each student has a number in the air. I'll then ask the "threes" to get certain supplies, "ones" to grab their computers, and "twos" to hand out papers (or whatever is needed for the lesson). This management strategy has proven to be effective when cleaning up and returning supplies as well!
Lesson Introduction & Goal
I review the learning goal: I can describe the movement of matter among plants, animals, and decomposers.
Yesterday, we began studying how matter flows between the organisms in the food chain. Today, we are going to take a closer look at even more ways that matter is recycled in ecosystems and we're also going to take a closer look at the six essential nutrients for animals. At the end of today's lesson, you'll get the chance to add on to your paragraphs from yesterday!
Vocabulary & Poster Review
I take a moment to review the Food Chain Vocabulary Poster. We discuss how food chains help demonstrate the movement of energy and matter in an ecosystem.
This leads us into a review of how matter moves through food chains by reviewing the blue cards on the poster from yesterday: Poster with Blue Cards.
Matter is anything that has mass and takes up space. We know that matter (such as nutrients, water, and air) can move between organisms in a food chain because when a rabbit eats grass, it is also eating nutrients and water. When a plant dies, the nutrients, water, and gases are recycled back to the soil by decomposers. There are many types of nutrients that flow through a food chain. There are non-mineral nutrients (such as hydrogen and oxygen, which can be found in the air or as water... H20). There are also mineral nutrients (such as nitrate and phosphate, which actually come from weathered rocks). Finally, there are food nutrients, such as proteins and fats.
Today, I also want to point out how sometimes matter, such as water and air, flows through the environment to get to other organisms.
Adding the following blue cards one-by-one we discuss the following key ideas. Throughout this time, I ask students to turn and teach the new concepts. This promotes active listening and higher engagement.
- Plants Take in Water & Plants Release Oxygen: We've studied how plants take in water and carbon dioxide and they release oxygen into the air when they produce their own food during photosynthesis. Plants also release a little carbon dioxide, but the amount is very little when compared to how much carbon dioxide plants take in. Turn and teach: What do plants take in and release into the environment?
- Animals Take in & Release: Animals can then in the oxygen that plants release into the air. Animals use this oxygen for cellular respiration. This is where animal release energy from sugars. During this process, animals also release carbon dioxide into the air. This carbon dioxide will then be used by plants. Animals also take in water by eating and drinking. Turn and teach: What do animals take in and release into the environment?
- Animals Release & Absorb: Animals also release urine into the environment. Urine is 95% water and it also contains sodium, potassium, and nitrogen. Animal waste is 75% water and it contains undigested food, bacteria, fat, and proteins. Animal urine and waste can be recycled back into the environment so that plants and animals are able to reuse the water and other nutrients. Eventually, these nutrients will be reused again by animals! You may be wondering how animals absorb nutrients. Well, we absorb nutrients in the intestines. Then these nutrients go into the bloodstream and are carried to cells throughout our bodies! Turn and teach: How do the nutrients in animal urine and waste move on to help other organisms in the environment?
To help make the movement of matter in ecosystems even more meaningful to students I show the following video on the 6 Essential Nutrients that were introduced yesterday (6 Essential Nutrients). I want students to explore why the movement of matter (such as nutrients) in food chains is so important. Before beginning, I pose the following questions: Why are the six essential nutrients so important to animals? How do you think they help humans? Turn and Talk!
I ask students to take notes on the video in their science journals. Students make a two column t-chart with the nutrients listed on the left side and how the nutrients help animals on the right side. Here are a couple of finished examples: Student Notes Example 1 and Student Notes Example 2.
Throughout the video, we pause and discuss the importance of each nutrient. With time, students begin to see the benefits of each nutrient and how the movement of matter within environments supports human life.
Nutrients in Food
At this time, I pass out a variety of Food Boxes and ask students to look for food nutrients on the labels. I want students to actually see how matter moving in the food chain impacts their daily lives! Here, Students Explaining Nutrients in Food, I walk around the room as students share the food nutrients found in their boxes of food!
Teacher Note: Looking at the nutrients in boxes of food is a spontaneous addition to today's lesson. To build off of today's learning, we could discuss the healthiness of different types of food. In addition, I could ask students to analyze the food boxes and to make a list of research questions... such as, "How does iron help the human body?"
Reflect & Apply
At the end of today's lesson, students continue writing their paragraphs from yesterday. The main idea sentence reads: Matter flows through plants, animals, and decomposers in an ecosystem.
Monitoring Student Understanding
Once students begin working, I conference with as many students as possible. My goal is to support students by asking guiding questions (listed below). I also want to encourage students to engage in Science & Engineering Practice 7: Engaging in Argument from Evidence.
- Do you agree that _?
- What do you think about _?
- What is most important?
- What would happen if_?
- What does this remind you of?
- Are you surprised by anything?
- How has this text changed your thinking?
- What conclusion can you draw about ____?
While conferencing with students, I found the following:
- Student A: Focusing more on writing about the food chain than on the flow of matter (My response: What is the topic of this paragraph? (the flow of matter through food chains) What do you think your audience will want to hear more about? (the flow of matter)
- Student B: Explaining matter as anything that has mass and takes up a lot of space. (My response: A pencil is made of matter. Does it take up a lot of space? So does matter have to take up a lot of space or does matter simply take up space?)
- Student C: Describing a food chain as a series of animals eating other animals to survive. (My response: Is it just animals in a food chain?)
Here are some examples of student paragraphs from today: | <urn:uuid:96db121a-1ac6-4260-900f-f984e1c4d5c0> | 3.75 | 2,693 | Tutorial | Science & Tech. | 47.751995 | 95,483,276 |
Late Holocene climate: Natural or anthropogenic?
MetadataShow full item record
©2015. American Geophysical Union. All Rights Reserved. For more than a decade, scientists have argued about the warmth of the current interglaciation. Was the warmth of the preindustrial late Holocene natural in origin, the result of orbital changes that had not yet driven the system into a new glacial state? Or was it in considerable degree the result of humans intervening in the climate system through greenhouse gas emissions from early agriculture? Here we summarize new evidence that moves this debate forward by testing both hypotheses. By comparing late Holocene responses to those that occurred during previous interglaciations (in section 2), we assess whether the late Holocene responses look different (and thus anthropogenic) or similar (and thus natural). This comparison reveals anomalous (anthropogenic) signals. In section 3, we review paleoecological and archaeological syntheses that provide ground truth evidence on early anthropogenic releases of greenhouse gases. The available data document large early anthropogenic emissions consistent with the anthropogenic ice core anomalies, but more information is needed to constrain their size. A final section compares natural and anthropogenic interpretations of the δ13C trend in ice core CO2.
The following license files are associated with this item: | <urn:uuid:48238e1b-0915-4746-a5fe-7017fa96299e> | 3 | 267 | Academic Writing | Science & Tech. | 13.788255 | 95,483,279 |
The study, published today by the journal Climatic Change, finds a strong connection between U.S. weather trends and public and media attitudes towards climate science over the past 20 years – with skepticism about global warming increasing during cold snaps and concern about climate change growing during hot spells.
"Our findings help to explain some of the significant fluctuations and inconsistencies in U.S. public opinion on climate change," says UBC Geography Prof. Simon Donner who conducted the study with former student Jeremy McDaniels (now at Oxford University).
The researchers used 1990-2010 data from U.S. public opinion polls and media coverage by major U.S. newspapers, including The New York Times, Washington Post, The Wall Street Journal and USA Today. They evaluated the relationship between average national temperatures and opinion polls on climate change, along with the quantity and nature of media editorials and opinion pieces related to climate change.
While many factors affect climate change attitudes – political views, media coverage, personal experience and values – the researchers suggest that headline-making weather can strongly influence climate beliefs, especially for individuals without strong convictions for or against climate change.
"Our study demonstrates just how much local weather can influence people's opinions on global warming," says Donner. "We find that, unfortunately, a cold winter is enough to make some people, including many newspaper editors and opinion leaders, doubt the overwhelming scientific consensus on the issue."
Basil Waugh | EurekAlert!
Innovative genetic tests for children with developmental disorders and epilepsy
11.07.2018 | Christian-Albrechts-Universität zu Kiel
Oxygen loss in the coastal Baltic Sea is “unprecedentedly severe”
05.07.2018 | European Geosciences Union
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:4011f056-fb08-49d7-896e-a6d655a1fc55> | 3.4375 | 885 | Content Listing | Science & Tech. | 33.772208 | 95,483,281 |
Carbon Capture and Sequestration: Carbon diamond in rough
This is the process of capturing waste carbon dioxide (CO2) from large point sources, such as fossil fuel power plants, transferring it to a storage site, and dumping it where it will not enter the atmosphere, normally an underground geological formation. The aim is to prevent the release of large quantities of CO2 into the atmosphere (from fossil fuel use in power generation and other industries) that cause environmental pollution. It is a potential means of mitigating the impact of fossil fuel emissions to global warming and ocean acidification. Although CO2 has been injected into geological formations for several decades for various purposes including enhanced oil recovery, the long term storage of CO2 is a relatively new concept. The first commercial example was Weyburn in 2000. Carbon capture and sequestration can also be used to describe the scrubbing of CO2 from ambient air as a geo engineering technique.
CCS applied to a modern conventional power plant could reduce CO2 discharges to the atmosphere by approximately 80-90% compared to a plant without CCS. The IPCC estimates that the economic potential of CCS could be between 10% and 55% of the total carbon mitigation effort until year 2100. Capturing and compressing CO2 may increase the fuel needs of a coal-fired CCS plant by 25-40%.
CARBON CAPTURE TECHNIQUES
Broadly, three different types of technologies for cleaning exist: post-combustion, pre-combustion, and oxyfuel combustion. Concentrated CO2 from the combustion of coal in oxygen is relatively pure, and could be directly processed. Impurities in CO2 streams could have a significant effect on their phase behaviour and could pose a significant threat of increased corrosion of pipeline and well materials. In instances where CO2 impurities exist and especially with air capture, a scrubbing process would be needed.
* Post combustion capture, the CO2 is removed after combustion of the fossil fuel this is the scheme that would be applied to fossil-fuel burning power plants. Here, CO2 is captured from flue gases at power stations or other large point sources. The technology is well assumed and is currently used in other industrial applications, although not at the same scale as might be required in a commercial scale power station.
* Pre combustion is widely applied in fertilizer, chemical, gaseous fuel (H2, CH4), and power production. In these cases, the fossil fuel is partially oxidized, for instance in a gasifier. The resulting syngas (CO and H2) is shifted into CO2 and H2. The resulting CO2 can be captured from a relatively pure exhaust stream. The H2 can now be used as fuel; the carbon dioxide is removed before combustion takes place. There are several advantages and disadvantages when compared to conventional post combustion carbon dioxide capture. The CO2 is removed after combustion of fossil fuels, but before the flue gas is expanded to atmospheric pressure. This scheme is applied to new fossil fuel burning power plants, or to existing plants where re-powering is an option.
* Oxy fuel combustion the fuel is burned in oxygen instead of air. To limit the resulting flame temperatures to levels common during conventional combustion, cooled flue gas is re-circulated and injected into the combustion chamber. The flue gas consists of mainly carbon dioxide and water vapours, the latter of which is condensed through cooling. The result is an almost pure carbon dioxide stream that can be transported to the sequestration site and stored.
After capture, the CO2 would have to be transported to suitable storage sites. This is done by pipeline, which is generally the cheapest form of transport. The injection of CO2 to produce oil is generally called Enhanced Oil Recovery or EOR. In addition, there are several pilot programmes in various stages to test the long-term storage of CO2 in non-oil producing geologic formations. Ships could also be utilized for transport where pipelines are not feasible. These methods are currently used for transporting CO2 for other applications.
SEQUESTRATION OR STORAGE
Various forms have been perceived for permanent storage of CO2. These forms contain gaseous storage in several deep geological creations (including saline formations and exhausted gas fields), and solid storage by reaction of CO2 with metal oxides to harvest stable carbonates.
This method involves injecting carbon dioxide, generally in supercritical form, directly into underground geological formations. Oil fields, gas fields, saline formations, unmineable coal seams, and saline-filled basalt formations have been suggested as storage sites. Various physical and geochemical trapping mechanisms would prevent the CO2 from escaping to the surface.
Carbon dioxide could be stored in the oceans, but this would only aggravate ocean acidification and has been made illegal under specific regulations. Ocean storage is no longer considered feasible. The ocean contains an estimated 40,000 Gt of carbon, whereas the atmosphere and the terrestrial biosphere contain an estimated 750 and 2200 Gt, correspondingly. A doubling of the carbon concentration levels in the atmosphere, therefore, represents only enough carbon to increase the oceans concentration levels by about 2%. By direct injection into the ocean, this natural process is effectively enhanced, thus reducing peak atmospheric carbon dioxide concentrations and their rate of increase. However, using this method, it is estimated that around 15-20% of the carbon dioxide injected into the ocean will leach back into the atmosphere over hundreds of year.
There have been a number of injection techniques suggested in order to dissolve the carbon
dioxide into the ocean. These are
1. Droplet plume-liquid CO2 injected from a multiple below 1000 m, forming a rising plume.
2. Dense plume-a dense CO2 seawater mix that sinks, injected at a depth between 500 and
3. Dry ice-dropped off a boat and allowed to sink and diffuse.
4. Towed pipe-injected from a boat at a depth of 1000 m, forming a rising plume.
5. CO2 lake-injection at a depth of around 4000 m to form a stable deep lake.
In the short term, the droplet plume and towed pipe methods are probably the most viable due
to technological and economic reasons.
Natural terrestrial sequestration
Terrestrial sequestration involves the capture and storage of carbon dioxide by plants and the storage of carbon in to soil. During photosynthesis, carbon from atmospheric carbon dioxide is transformed into components essential for plants to live and grow. As part of this process, the carbon present in the atmosphere as carbon dioxide becomes part of the planta leaf, stem, root, etc. Long-lived plants like trees might keep the carbon sequestered for a long period of time. Once the tree dies, or as limbs, leaves, seeds, or blossoms drop from the tree, the plant material decomposes and the carbon is released that can be captured with several techniques and stored in to soil.
The notional merit of CCS systems is the decline of CO2 discharges by up to 90%, depending on plant type. Generally, environmental effects from use of CCS arise during power production, CO2 capture, transport, industries and storage.
Additional energy is required for CO2 capture, and this means that substantially more fuel has to be used to produce the same amount of power, depending on the plant type. For new super-critical pulverized coal (PC) plants using current technology, the extra energy requirements range from 24 to 40%, while for natural gas combined cycle (NGCC) plants the range is 11-22% and for coal-based or ignitions gasification combined cycle (IGCC) systems it is 14-25%. Apparently, fuel use and environmental problems arising from mining and withdrawal of coal or gas increase accordingly.
Plants equipped with flue-gas desulfurization (FGD) systems for sulfur dioxide control require proportionally greater amounts of limestone, and systems equipped withselective catalytic reduction systems for nitrogen oxides produced during combustion require proportionally greater amounts of ammonia. Carbon is drastically reduced though never completely captured, emissions of air pollutants increase significantly.
The authors are from the Department of Agronomy University of Agriculture, Faisalabad, Punjab, Pakistan. They can be reached at email@example.com
https://www.technologytimes.pk/carbon-capture-and-sequestration-carbon-diamond-in-rough/Articlescapture,Carbon,diamond,rough,sequestration This is the process of capturing waste carbon dioxide (CO2) from large point sources, such as fossil fuel power plants, transferring it to a storage site, and dumping it where it will not enter the atmosphere, normally an underground geological formation. The aim is to prevent the release of...Technology TimesTechnology Times firstname.lastname@example.orgAdministratorTechnology Times is Pakistan's First Newspaper on Science and TechnologyTechnology Times | <urn:uuid:5b49152b-7fd9-416a-8585-22794294b93a> | 3.65625 | 1,839 | Knowledge Article | Science & Tech. | 33.391612 | 95,483,303 |
Solar storm of 2012
The solar storm of 2012 was an unusually large and strong coronal mass ejection (CME) event that occurred on July 23 that year. It missed the Earth with a margin of approximately nine days, as the Sun rotates around its own axis with a period of about 25 days. The region that produced the outburst was thus not pointed directly towards the Earth at that time. The strength of the eruption was comparable to the 1859 Carrington event that caused damage to electric equipment worldwide, which at that time consisted mostly of telegraph stations.
The eruption tore through Earth's orbit, hitting the STEREO-A spacecraft. The spacecraft is a solar observatory equipped to measure such activity, and because it was far away from the Earth and thus not exposed to the strong electrical currents that can be induced when a CME hits the Earth's magnetosphere, it survived the encounter and provided researchers with valuable data.
Based on the collected data, the eruption consisted of two separate ejections which were able to reach exceptionally high strength as the interplanetary medium around the Sun had been cleared by a smaller CME four days earlier. Had the CME hit the Earth, it is likely that it would have inflicted serious damage to electronic systems on a global scale. A 2013 study estimated that the economic cost to the United States would have been between $0.6 and 2.6 trillion USD. Ying D. Liu, professor at China's State Key Laboratory of Space Weather, estimated that the recovery time from such a disaster would have been about four to ten years.
- Williams, D. R. (1 July 2013). "Sun Fact Sheet". NASA. Retrieved 13 January 2015.
- Phillips, Tony (23 July 2014). "Near Miss: The Solar Superstorm of July 2012". Science@NASA. NASA. Retrieved 10 January 2015.
- Solar Storm Risk to the North American Electric Grid Lloyd's 2013
- Sanders, Robert (18 March 2014). "Fierce solar magnetic storm barely missed Earth in 2012". UC Berkeley News Center. Retrieved 10 January 2015.
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http://lizhingley.com/news/ http://oceanadesigns.net/images/granite/bianco-sardo/bianco-sardo.jpg All spiders are predators, but most of them are small and have rudimentary defences against larger animals that in turn prey on them. Spiders have thus evolved a range of predatory behaviours that, at the same time, allow them to evade the threat of predation – and some of the most effective strategies involve deceiving ants.
Life as a worker ant is hard enough as it is. But carpenter ants foraging for food in the rainforest must deal with an additional threat: a parasitic fungus that takes over their body and controls their every move. Continue reading | <urn:uuid:72a46e51-9664-4a68-9842-74ce72619d84> | 2.703125 | 151 | Truncated | Science & Tech. | 44.757727 | 95,483,345 |
The Caterpillar eventually Transitions into the Adult Butterfly! If your Class wishes to Make a Fun Mini-Butterfly House, Materials required are: Caterpillars (can be purchased in a Pet Store or online); Milkweed (or similar plant type); Small Twigs, Leaves, and other plant matter; Terrarium with Lid
There are 4 stages for the Butterfly’s life cycle. They are: The Egg, The Larva, The Pupa, and The Adult. The Egg – is the unborn stage. In this stage the eggs are laid by the Female Butterfly. She will generally lay her eggs on plants. The plants will be the food source for the growing Butterfly when it hatches from the egg as the caterpillar. The Female Butterfly lays eggs in the every season, except for the winter. The exact egg-laying time depends on the species of Butterfly. During each laying, hundreds of eggs are released. Butterfly Eggs are very, very small. There is a high chance that most eggs laid will not become Butterflies, so the female lays as many eggs as she can in the hopes that at least some will grow, hatch, and survive. (Photo: http://commons.wikimedia.org/wiki/File:Harlequin_Butterfly_Life_Cycle_Mariposa_arlequ%C3%ADn_%285840511508%29.jpg)
The Larva – After the egg has been laid, the next stage is the larva stage. The “Baby” emerges from the egg and is called a Caterpillar. The main job of the Caterpillar is to eat as much as it possibly can. The Caterpillar will eat and eat and grow and grow during this stage. The Caterpillar will grow so much that it will have to split and shed its skin at least 4 times. As the caterpillar eats the food is stored for it to use in later stages.
The Pupa – The Caterpillar will enter this stage after it is full grown and has eaten all it can eat. For Butterflies the pupa is called a Chrysalis. The Chrysalis may attach under a branch, bury itself underground, or hide in leaves. Different species of Butterflies spend this stage in different ways. During this stage, the Cocoon is formed to protect the growing Pupa. This stage could last up to a month! Some species are known to be in this stage for two years!
This is when the Metamorphosis or the big change occurs. Parts of the pupa will grow very quickly to make the wings, legs, and eyes of the Adult Butterfly. The stored food from the larva stage will be what the pupa lives off of as it grows inside of the Cocoon.
Did you know a Caterpillar can grow over 100 times bigger than it was when it First hatched? Most caterpillars are the size of a pen tip when they first hatch but can grow to be 2 inches long within the matter of 2 weeks!
For Other Articles on Earth Science Activities, ou Can Visit: http://www.science-lessons.ca/blog/ | <urn:uuid:7e6c15f6-f168-49a2-ae00-c74b8b72518f> | 3.875 | 652 | Knowledge Article | Science & Tech. | 65.899 | 95,483,363 |
A term that most of you in the sciences may have heard quite consistently in recent years is the term “ http://sdsignshop.com/product/directional-sign-18″t-x-24″w-use-my-artwork/?add_to_wishlist=2481 DNA barcoding.” It sounds like science (DNA = science, am I right?) and a grocery store (all the bags of chips I buy have barcodes to scan) got together and just outputted that term after a fun night of partying. However, there’s a lot more to it and it has been dramatically changing how scientists perform scientific research.
http://stivesarchive.co.uk/propranolol-40-generic-in-australia-propranolol-40-mail-order-category-propranolol/ So what is DNA barcoding? In a very simple form, it is the comparison of a short segment of DNA with a library of previously recorded DNA barcodes (other short segments of DNA). In other words, comparing unknown specimens to known specimens.
Now, why should we care about it? There are many uses for DNA barcoding, which include species identification for marketplace fraud (is it really salmon that’s in your sushi?), forensics (is that souvenir you bought in Thailand made of ivory? Let’s hope not!), environmental monitoring (quickly identifying insect species because there are way too many of those tiny small flies) and so much more! One of the most important reasons I believe that DNA barcoding is essential to our understanding, is that it allows us to work within a taxonomic impediment. With the various negative impacts associated with climate change, one of the most alarming results is the heightened rate of species extinction. Since we are constantly discovering new species of animals, especially insects, we are in a race with time to identify all of our planet’s species before they go extinct. Through DNA barcoding, we can identify species at a rate that is much faster than before.
In a little bit more detail, DNA barcoding can be divided into 4 main steps, and I will explain these steps with what I do at the Biodiversity Institute of Ontario (BIO) with insects. Yes guys, I’m a scientist:
- Specimen collection and processing -> involves me setting up a bunch of traps (Malaise traps, Pitfall traps, sweep netting, etc.) to collect insects in the field. After catching insects, I will take them back to BIO to sort them into orders (ex. Dipera : flies, Hymenoptera : wasps, bees, ants, Coleoptera : beetles). The specimens will then be tissue sampled, usually by pulling a single leg from the insect, or putting an entire tiny specimen into a microplate well.
- Laboratory analysis -> the tissue samples are applied a primer to locate a specific region of the DNA, usually 658 base pairs of the mitochondrial cytochrome oxidase 1 gene for insects. This is the “DNA barcode.”
- Data-basing the specimens -> once we have the barcode, we upload all of the information regarding that specimen into the Barcode of Life Data systems (BOLD). BOLD is an online reference library of barcodes. Some of the information includes where the specimen was caught (latitude, longitude, country, exact site), when it was caught, how it was caught, specimen image, sequence info, etc.
- The Data Analysis -> we will then compare the barcodes with barcodes we have previously acquired through field sampling, museums and other collaborators. So either the specimen will match at least one of the existing barcodes OR we consider it to be a new species in our database! Currently, as of March 19th, 2016, we have 4, 779, 816 barcode sequences, that fall into 444,161 Barcode Index Numbers (BINs) – a proxy for species.
Now after that information overload, I hope all of you guys have a better understanding of DNA barcoding and continue to support its many uses, so I can continue to have a job… Just kidding, but all of us in the sciences definitely need more funding for scientific research. *hint hint* @ Government of Canada.
Written by Thanushi Eagalle | <urn:uuid:ff0d39e5-f9c1-4796-9540-aeb216975f18> | 2.625 | 916 | Personal Blog | Science & Tech. | 45.516341 | 95,483,365 |
Wave(Redirected from Wave (physics))
In physics, a wave is a disturbance that transfers energy through matter or space, with little or no associated mass transport. Waves consist of oscillations or vibrations of a physical medium or a field, around relatively fixed locations.
There are two main types of waves: mechanical and electromagnetic. Mechanical waves propagate through a physical matter, whose substance is being deformed. Restoring forces then reverse the deformation. For example, sound waves propagate via air molecules colliding with their neighbours. When the molecules collide, they also bounce away from each other (a restoring force). This keeps the molecules from continuing to travel in the direction of the wave. Electromagnetic waves do not require a medium. Instead, they consist of periodic oscillations of electrical and magnetic fields originally generated by charged particles, and can therefore travel through a vacuum. These types vary in wavelength, and include radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.
Waves are described by a wave equation which sets out how the disturbance proceeds over time. The mathematical form of this equation varies depending on the type of wave. Further, the behavior of particles in quantum mechanics are described by waves. In addition, gravitational waves also travel through space, which are a result of a vibration or movement in gravitational fields.
A wave can be transverse, where a disturbance creates oscillations that are perpendicular to the propagation of energy transfer, or longitudinal: the oscillations are parallel to the direction of energy propagation. While mechanical waves can be both transverse and longitudinal, all electromagnetic waves are transverse in free space.
A single, all-encompassing definition for the term wave is not straightforward. A vibration can be defined as a back-and-forth motion around a reference value. However, a vibration is not necessarily a wave. An attempt to define the necessary and sufficient characteristics that qualify a phenomenon as a wave results in a blurred line.
The term wave is often intuitively understood as referring to a transport of spatial disturbances that are generally not accompanied by a motion of medium occupying this space as a whole. In a wave, the energy of a vibration is moving away from the source in the form of a disturbance within the surrounding medium (Hall 1982, p. 8). However, this motion is problematic for a standing wave (for example, a wave on a string), where energy is moving in both directions equally, or for electromagnetic (e.g., light) waves in a vacuum, where the concept of medium does not apply and interaction with a target is the key to wave detection and practical applications. There are water waves on the ocean surface; gamma waves and light waves emitted by the Sun; microwaves used in microwave ovens and in radar equipment; radio waves broadcast by radio stations; and sound waves generated by radio receivers, telephone handsets and living creatures (as voices), to mention only a few wave phenomena.
It may appear that the description of waves is closely related to their physical origin for each specific instance of a wave process. For example, acoustics is distinguished from optics in that sound waves are related to a mechanical rather than an electromagnetic wave transfer caused by vibration. Concepts such as mass, momentum, inertia, or elasticity, become therefore crucial in describing acoustic (as distinct from optic) wave processes. This difference in origin introduces certain wave characteristics particular to the properties of the medium involved. For example, in the case of air: vortices, radiation pressure, shock waves etc.; in the case of solids: Rayleigh waves, dispersion; and so on.
Other properties, however, although usually described in terms of origin, may be generalized to all waves. For such reasons, wave theory represents a particular branch of physics that is concerned with the properties of wave processes independently of their physical origin. For example, based on the mechanical origin of acoustic waves, a moving disturbance in space–time can exist if and only if the medium involved is neither infinitely stiff nor infinitely pliable. If all the parts making up a medium were rigidly bound, then they would all vibrate as one, with no delay in the transmission of the vibration and therefore no wave motion. On the other hand, if all the parts were independent, then there would not be any transmission of the vibration and again, no wave motion. Although the above statements are meaningless in the case of waves that do not require a medium, they reveal a characteristic that is relevant to all waves regardless of origin: within a wave, the phase of a vibration (that is, its position within the vibration cycle) is different for adjacent points in space because the vibration reaches these points at different times repeatedly .
Mathematical description of one-dimensional wavesEdit
- in the direction in space. E.g., let the positive direction be to the right, and the negative direction be to the left.
- with constant amplitude
- with constant velocity , where is
- with constant waveform, or shape
This wave can then be described by the two-dimensional functions
- (waveform traveling to the right)
- (waveform traveling to the left)
The form or shape of F in d'Alembert's formula involves the argument x − vt. Constant values of this argument correspond to constant values of F, and these constant values occur if x increases at the same rate that vt increases. That is, the wave shaped like the function F will move in the positive x-direction at velocity v (and G will propagate at the same speed in the negative x-direction).
In the case of a periodic function F with period λ, that is, F(x + λ − vt) = F(x − vt), the periodicity of F in space means that a snapshot of the wave at a given time t finds the wave varying periodically in space with period λ (the wavelength of the wave). In a similar fashion, this periodicity of F implies a periodicity in time as well: F(x − v(t + T)) = F(x − vt) provided vT = λ, so an observation of the wave at a fixed location x finds the wave undulating periodically in time with period T = λ/v.
Amplitude and modulationEdit
The amplitude of a wave may be constant (in which case the wave is a c.w. or continuous wave), or may be modulated so as to vary with time and/or position. The outline of the variation in amplitude is called the envelope of the wave. Mathematically, the modulated wave can be written in the form:
showing that the envelope moves with the group velocity and retains its shape. Otherwise, in cases where the group velocity varies with wavelength, the pulse shape changes in a manner often described using an envelope equation.
Phase velocity and group velocityEdit
Phase velocity is the rate at which the phase of the wave propagates in space: any given phase of the wave (for example, the crest) will appear to travel at the phase velocity. The phase velocity is given in terms of the wavelength λ (lambda) and period T as
Group velocity is a property of waves that have a defined envelope, measuring propagation through space (i.e. phase velocity) of the overall shape of the waves' amplitudes—modulation or envelope of the wave.
Mathematically, the most basic wave is the (spatially) one-dimensional sine wave (or harmonic wave or sinusoid) with an amplitude described by the equation:
- is the maximum amplitude of the wave, maximum distance from the highest point of the disturbance in the medium (the crest) to the equilibrium point during one wave cycle. In the illustration to the right, this is the maximum vertical distance between the baseline and the wave.
- is the space coordinate
- is the time coordinate
- is the wavenumber
- is the angular frequency
- is the phase constant.
The units of the amplitude depend on the type of wave. Transverse mechanical waves (e.g., a wave on a string) have an amplitude expressed as a distance (e.g., meters), longitudinal mechanical waves (e.g., sound waves) use units of pressure (e.g., pascals), and electromagnetic waves (a form of transverse vacuum wave) express the amplitude in terms of its electric field (e.g., volts/meter).
The wavelength is the distance between two sequential crests or troughs (or other equivalent points), generally is measured in meters. A wavenumber , the spatial frequency of the wave in radians per unit distance (typically per meter), can be associated with the wavelength by the relation
The period is the time for one complete cycle of an oscillation of a wave. The frequency is the number of periods per unit time (per second) and is typically measured in hertz denoted as Hz. These are related by:
In other words, the frequency and period of a wave are reciprocals.
The angular frequency represents the frequency in radians per second. It is related to the frequency or period by
The wavelength of a sinusoidal waveform traveling at constant speed is given by:
where is called the phase speed (magnitude of the phase velocity) of the wave and is the wave's frequency.
Wavelength can be a useful concept even if the wave is not periodic in space. For example, in an ocean wave approaching shore, the incoming wave undulates with a varying local wavelength that depends in part on the depth of the sea floor compared to the wave height. The analysis of the wave can be based upon comparison of the local wavelength with the local water depth.
Although arbitrary wave shapes will propagate unchanged in lossless linear time-invariant systems, in the presence of dispersion the sine wave is the unique shape that will propagate unchanged but for phase and amplitude, making it easy to analyze. Due to the Kramers–Kronig relations, a linear medium with dispersion also exhibits loss, so the sine wave propagating in a dispersive medium is attenuated in certain frequency ranges that depend upon the medium. The sine function is periodic, so the sine wave or sinusoid has a wavelength in space and a period in time.
The sinusoid is defined for all times and distances, whereas in physical situations we usually deal with waves that exist for a limited span in space and duration in time. Fortunately, an arbitrary wave shape can be decomposed into an infinite set of sinusoidal waves by the use of Fourier analysis. As a result, the simple case of a single sinusoidal wave can be applied to more general cases. In particular, many media are linear, or nearly so, so the calculation of arbitrary wave behavior can be found by adding up responses to individual sinusoidal waves using the superposition principle to find the solution for a general waveform. When a medium is nonlinear, the response to complex waves cannot be determined from a sine-wave decomposition.
A standing wave, also known as a stationary wave, is a wave that remains in a constant position. This phenomenon can occur because the medium is moving in the opposite direction to the wave, or it can arise in a stationary medium as a result of interference between two waves traveling in opposite directions.
The sum of two counter-propagating waves (of equal amplitude and frequency) creates a standing wave. Standing waves commonly arise when a boundary blocks further propagation of the wave, thus causing wave reflection, and therefore introducing a counter-propagating wave. For example, when a violin string is displaced, transverse waves propagate out to where the string is held in place at the bridge and the nut, where the waves are reflected back. At the bridge and nut, the two opposed waves are in antiphase and cancel each other, producing a node. Halfway between two nodes there is an antinode, where the two counter-propagating waves enhance each other maximally. There is no net propagation of energy over time.
A two-dimensional standing wave on a disk; this is the fundamental mode.
A standing wave on a disk with two nodal lines crossing at the center; this is an overtone.
Waves exhibit common behaviors under a number of standard situations, e. g.
Transmission and mediaEdit
Waves normally move in a straight line (i.e. rectilinearly) through a transmission medium. Such media can be classified into one or more of the following categories:
- A bounded medium if it is finite in extent, otherwise an unbounded medium
- A linear medium if the amplitudes of different waves at any particular point in the medium can be added
- A uniform medium or homogeneous medium if its physical properties are unchanged at different locations in space
- An anisotropic medium if one or more of its physical properties differ in one or more directions
- An isotropic medium if its physical properties are the same in all directions
Absorption of waves means, if a kind of wave strikes a matter, it will be absorbed by the matter. When a wave with that same natural frequency impinges upon an atom, then the electrons of that atom will be set into vibrational motion. If a wave of a given frequency strikes a material with electrons having the same vibrational frequencies, then those electrons will absorb the energy of the wave and transform it into vibrational motion.
When a wave strikes a reflective surface, it changes direction, such that the angle made by the incident wave and line normal to the surface equals the angle made by the reflected wave and the same normal line.
Refraction is the phenomenon of a wave changing its speed. Mathematically, this means that the size of the phase velocity changes. Typically, refraction occurs when a wave passes from one medium into another. The amount by which a wave is refracted by a material is given by the refractive index of the material. The directions of incidence and refraction are related to the refractive indices of the two materials by Snell's law.
A wave exhibits diffraction when it encounters an obstacle that bends the wave or when it spreads after emerging from an opening. Diffraction effects are more pronounced when the size of the obstacle or opening is comparable to the wavelength of the wave.
The phenomenon of polarization arises when wave motion can occur simultaneously in two orthogonal directions. Transverse waves can be polarized, for instance. When polarization is used as a descriptor without qualification, it usually refers to the special, simple case of linear polarization. A transverse wave is linearly polarized if it oscillates in only one direction or plane. In the case of linear polarization, it is often useful to add the relative orientation of that plane, perpendicular to the direction of travel, in which the oscillation occurs, such as "horizontal" for instance, if the plane of polarization is parallel to the ground. Electromagnetic waves propagating in free space, for instance, are transverse; they can be polarized by the use of a polarizing filter.
Longitudinal waves, such as sound waves, do not exhibit polarization. For these waves there is only one direction of oscillation, that is, along the direction of travel.
A wave undergoes dispersion when either the phase velocity or the group velocity depends on the wave frequency. Dispersion is most easily seen by letting white light pass through a prism, the result of which is to produce the spectrum of colours of the rainbow. Isaac Newton performed experiments with light and prisms, presenting his findings in the Opticks (1704) that white light consists of several colours and that these colours cannot be decomposed any further.
Waves on stringsEdit
where the linear density μ is the mass per unit length of the string.
Acoustic or sound waves travel at speed given by
or the square root of the adiabatic bulk modulus divided by the ambient fluid density (see speed of sound).
- Ripples on the surface of a pond are actually a combination of transverse and longitudinal waves; therefore, the points on the surface follow orbital paths.
- Sound—a mechanical wave that propagates through gases, liquids, solids and plasmas;
- Inertial waves, which occur in rotating fluids and are restored by the Coriolis effect;
- Ocean surface waves, which are perturbations that propagate through water.
Seismic waves are waves of energy that travel through the Earth's layers, and are a result of earthquakes, volcanic eruptions, magma movement, large landslides and large man-made explosions that give out low-frequency acoustic energy.
A shock wave is a type of propagating disturbance. When a wave moves faster than the local speed of sound in a fluid, it is a shock wave. Like an ordinary wave, a shock wave carries energy and can propagate through a medium; however, it is characterized by an abrupt, nearly discontinuous change in pressure, temperature and density of the medium.
- Waves of traffic, that is, propagation of different densities of motor vehicles, and so forth, which can be modeled as kinematic waves
- Metachronal wave refers to the appearance of a traveling wave produced by coordinated sequential actions.
An electromagnetic wave consists of two waves that are oscillations of the electric and magnetic fields. An electromagnetic wave travels in a direction that is at right angles to the oscillation direction of both fields. In the 19th century, James Clerk Maxwell showed that, in vacuum, the electric and magnetic fields satisfy the wave equation both with speed equal to that of the speed of light. From this emerged the idea that light is an electromagnetic wave. Electromagnetic waves can have different frequencies (and thus wavelengths), giving rise to various types of radiation such as radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and Gamma rays.
Quantum mechanical wavesEdit
The Schrödinger equation describes the wave-like behavior of particles in quantum mechanics. Solutions of this equation are wave functions which can be used to describe the probability density of a particle.
The Dirac equation is a relativistic wave equation detailing electromagnetic interactions. Dirac waves accounted for the fine details of the hydrogen spectrum in a completely rigorous way. The wave equation also implied the existence of a new form of matter, antimatter, previously unsuspected and unobserved and which was experimentally confirmed. In the context of quantum field theory, the Dirac equation is reinterpreted to describe quantum fields corresponding to spin-½ particles.
de Broglie wavesEdit
where h is Planck's constant, and p is the magnitude of the momentum of the particle. This hypothesis was at the basis of quantum mechanics. Nowadays, this wavelength is called the de Broglie wavelength. For example, the electrons in a CRT display have a de Broglie wavelength of about 10−13 m.
A wave representing such a particle traveling in the k-direction is expressed by the wave function as follows:
where the wavelength is determined by the wave vector k as:
and the momentum by:
However, a wave like this with definite wavelength is not localized in space, and so cannot represent a particle localized in space. To localize a particle, de Broglie proposed a superposition of different wavelengths ranging around a central value in a wave packet, a waveform often used in quantum mechanics to describe the wave function of a particle. In a wave packet, the wavelength of the particle is not precise, and the local wavelength deviates on either side of the main wavelength value.
In representing the wave function of a localized particle, the wave packet is often taken to have a Gaussian shape and is called a Gaussian wave packet. Gaussian wave packets also are used to analyze water waves.
For example, a Gaussian wavefunction ψ might take the form:
at some initial time t = 0, where the central wavelength is related to the central wave vector k0 as λ0 = 2π / k0. It is well known from the theory of Fourier analysis, or from the Heisenberg uncertainty principle (in the case of quantum mechanics) that a narrow range of wavelengths is necessary to produce a localized wave packet, and the more localized the envelope, the larger the spread in required wavelengths. The Fourier transform of a Gaussian is itself a Gaussian. Given the Gaussian:
the Fourier transform is:
The Gaussian in space therefore is made up of waves:
that is, a number of waves of wavelengths λ such that kλ = 2 π.
The parameter σ decides the spatial spread of the Gaussian along the x-axis, while the Fourier transform shows a spread in wave vector k determined by 1/σ. That is, the smaller the extent in space, the larger the extent in k, and hence in λ = 2π/k.
Gravity waves are waves generated in a fluid medium or at the interface between two media when the force of gravity or buoyancy tries to restore equilibrium. A ripple on a pond is one example.
Gravitational waves also travel through space. The first observation of gravitational waves was announced on 11 February 2016. Gravitational waves are disturbances in the curvature of spacetime, predicted by Einstein's theory of general relativity.
Waves in generalEdit
- Wave equation, general
- Wave propagation, any of the ways in which waves travel
- Interference (wave propagation), a phenomenon in which two waves superpose to form a resultant wave
- Mechanical wave, in media transmission
- Wave Motion (journal), a scientific journal
- Wavefront, an advancing surface of wave propagation
- Airy wave theory, in fluid dynamics
- Capillary wave, in fluid dynamics
- Cnoidal wave, in fluid dynamics
- Edge wave, a surface gravity wave fixed by refraction against a rigid boundary
- Faraday wave, a type of wave in liquids
- Gravity wave, in fluid dynamics
- Sound wave, a wave of sound through a medium such as air or water
- Shock wave, in aerodynamics
- Internal wave, a wave within a fluid medium
- Tidal wave, a scientifically incorrect name for a tsunami
- Tollmien–Schlichting wave, in fluid dynamics
In quantum mechanicsEdit
Other specific types of wavesEdit
- Alfvén wave, in particle science
- Atmospheric wave, a periodic disturbance in the fields of atmospheric variables
- Fir wave, a forest configuration
- Lamb waves, in solid materials
- Rayleigh waves, surface acoustic waves that travel on solids
- Spin wave, in magnetism
- Spin-density wave, in solid materials
- Trojan wave packet, in particle science
- Waves in plasmas, in particle science
- Beat (acoustics)
- Doppler effect
- Envelope detector
- Group velocity
- Index of wave articles
- Inertial wave
- List of waves named after people
- Phase velocity
- Reaction–diffusion system
- Ripple tank
- Rogue wave
- Shallow water equations
- Shive wave machine
- Standing wave
- Transmission medium
- Wave turbulence
- Wind wave
- Lev A. Ostrovsky & Alexander I. Potapov (2001). Modulated waves: theory and application. Johns Hopkins University Press. ISBN 0-8018-7325-8.
- Michael A. Slawinski (2003). "Wave equations". Seismic waves and rays in elastic media. Elsevier. pp. 131 ff. ISBN 0-08-043930-6.
- Karl F Graaf (1991). Wave motion in elastic solids (Reprint of Oxford 1975 ed.). Dover. pp. 13–14. ISBN 978-0-486-66745-4.
- For an example derivation, see the steps leading up to eq. (17) in Francis Redfern. "Kinematic Derivation of the Wave Equation". Physics Journal.
- Jalal M. Ihsan Shatah; Michael Struwe (2000). "The linear wave equation". Geometric wave equations. American Mathematical Society Bookstore. pp. 37 ff. ISBN 0-8218-2749-9.
- Louis Lyons (1998). All you wanted to know about mathematics but were afraid to ask. Cambridge University Press. pp. 128 ff. ISBN 0-521-43601-X.
- Alexander McPherson (2009). "Waves and their properties". Introduction to Macromolecular Crystallography (2 ed.). Wiley. p. 77. ISBN 0-470-18590-2.
- Christian Jirauschek (2005). FEW-cycle Laser Dynamics and Carrier-envelope Phase Detection. Cuvillier Verlag. p. 9. ISBN 3-86537-419-0.
- Fritz Kurt Kneubühl (1997). Oscillations and waves. Springer. p. 365. ISBN 3-540-62001-X.
- Mark Lundstrom (2000). Fundamentals of carrier transport. Cambridge University Press. p. 33. ISBN 0-521-63134-3.
- Chin-Lin Chen (2006). "§13.7.3 Pulse envelope in nondispersive media". Foundations for guided-wave optics. Wiley. p. 363. ISBN 0-471-75687-3.
- Stefano Longhi; Davide Janner (2008). "Localization and Wannier wave packets in photonic crystals". In Hugo E. Hernández-Figueroa; Michel Zamboni-Rached; Erasmo Recami. Localized Waves. Wiley-Interscience. p. 329. ISBN 0-470-10885-1.
- David C. Cassidy; Gerald James Holton; Floyd James Rutherford (2002). Understanding physics. Birkhäuser. pp. 339 ff. ISBN 0-387-98756-8.
- Paul R Pinet (2009). op. cit. p. 242. ISBN 0-7637-5993-7.
- Mischa Schwartz; William R. Bennett & Seymour Stein (1995). Communication Systems and Techniques. John Wiley and Sons. p. 208. ISBN 978-0-7803-4715-1.
- See Eq. 5.10 and discussion in A. G. G. M. Tielens (2005). The physics and chemistry of the interstellar medium. Cambridge University Press. pp. 119 ff. ISBN 0-521-82634-9.; Eq. 6.36 and associated discussion in Otfried Madelung (1996). Introduction to solid-state theory (3rd ed.). Springer. pp. 261 ff. ISBN 3-540-60443-X.; and Eq. 3.5 in F Mainardi (1996). "Transient waves in linear viscoelastic media". In Ardéshir Guran; A. Bostrom; Herbert Überall; O. Leroy. Acoustic Interactions with Submerged Elastic Structures: Nondestructive testing, acoustic wave propagation and scattering. World Scientific. p. 134. ISBN 981-02-4271-9.
- Aleksandr Tikhonovich Filippov (2000). The versatile soliton. Springer. p. 106. ISBN 0-8176-3635-8.
- Seth Stein, Michael E. Wysession (2003). An introduction to seismology, earthquakes, and earth structure. Wiley-Blackwell. p. 31. ISBN 0-86542-078-5.
- Seth Stein, Michael E. Wysession (2003). op. cit.. p. 32. ISBN 0-86542-078-5.
Kimball A. Milton; Julian Seymour Schwinger (2006). Electromagnetic Radiation: Variational Methods, Waveguides and Accelerators. Springer. p. 16. ISBN 3-540-29304-3.
Thus, an arbitrary function f(r, t) can be synthesized by a proper superposition of the functions exp[i (k·r−ωt)]...
- Raymond A. Serway & John W. Jewett (2005). "§14.1 The Principle of Superposition". Principles of physics (4th ed.). Cengage Learning. p. 433. ISBN 0-534-49143-X.
Newton, Isaac (1704). "Prop VII Theor V". Opticks: Or, A treatise of the Reflections, Refractions, Inflexions and Colours of Light. Also Two treatises of the Species and Magnitude of Curvilinear Figures. 1. London. p. 118.
All the Colours in the Universe which are made by Light... are either the Colours of homogeneal Lights, or compounded of these...
- Anderson, John D. Jr. (January 2001) , Fundamentals of Aerodynamics (3rd ed.), McGraw-Hill Science/Engineering/Math, ISBN 0-07-237335-0
- M. J. Lighthill; G. B. Whitham (1955). "On kinematic waves. II. A theory of traffic flow on long crowded roads". Proceedings of the Royal Society of London. Series A. 229: 281–345. Bibcode:1955RSPSA.229..281L. doi:10.1098/rspa.1955.0088. And: P. I. Richards (1956). "Shockwaves on the highway". Operations Research. 4 (1): 42–51. doi:10.1287/opre.4.1.42.
- A. T. Fromhold (1991). "Wave packet solutions". Quantum Mechanics for Applied Physics and Engineering (Reprint of Academic Press 1981 ed.). Courier Dover Publications. pp. 59 ff. ISBN 0-486-66741-3.
(p. 61) ...the individual waves move more slowly than the packet and therefore pass back through the packet as it advances
- Ming Chiang Li (1980). "Electron Interference". In L. Marton; Claire Marton. Advances in Electronics and Electron Physics. 53. Academic Press. p. 271. ISBN 0-12-014653-3.
- See for example Walter Greiner; D. Allan Bromley (2007). Quantum Mechanics (2 ed.). Springer. p. 60. ISBN 3-540-67458-6. and John Joseph Gilman (2003). Electronic basis of the strength of materials. Cambridge University Press. p. 57. ISBN 0-521-62005-8.,Donald D. Fitts (1999). Principles of quantum mechanics. Cambridge University Press. p. 17. ISBN 0-521-65841-1..
- Chiang C. Mei (1989). The applied dynamics of ocean surface waves (2nd ed.). World Scientific. p. 47. ISBN 9971-5-0789-7.
- Walter Greiner; D. Allan Bromley (2007). Quantum Mechanics (2nd ed.). Springer. p. 60. ISBN 3-540-67458-6.
- Siegmund Brandt; Hans Dieter Dahmen (2001). The picture book of quantum mechanics (3rd ed.). Springer. p. 23. ISBN 0-387-95141-5.
- Cyrus D. Cantrell (2000). Modern mathematical methods for physicists and engineers. Cambridge University Press. p. 677. ISBN 0-521-59827-3.
- "Gravitational waves detected for 1st time, 'opens a brand new window on the universe'". CBC. 11 February 2016.
- Fleisch, D.; Kinnaman, L. (2015). A student's guide to waves. Cambridge, UK: Cambridge University Press. ISBN 978-1107643260.
- Campbell, Murray; Greated, Clive (2001). The musician's guide to acoustics (Repr. ed.). Oxford: Oxford University Press. ISBN 978-0198165057.
- French, A.P. (1971). Vibrations and Waves (M.I.T. Introductory physics series). Nelson Thornes. ISBN 0-393-09936-9. OCLC 163810889.
- Hall, D. E. (1980). Musical Acoustics: An Introduction. Belmont, California: Wadsworth Publishing Company. ISBN 0-534-00758-9..
- Hunt, Frederick Vinton (1978). Origins in acoustics. Woodbury, NY: Published for the Acoustical Society of America through the American Institute of Physics. ISBN 978-0300022209.
- Ostrovsky, L. A.; Potapov, A. S. (1999). Modulated Waves, Theory and Applications. Baltimore: The Johns Hopkins University Press. ISBN 0-8018-5870-4..
- Griffiths, G.; Schiesser, W. E. (2010). Traveling Wave Analysis of Partial Differential Equations: Numerical and Analytical Methods with Matlab and Maple. Academic Press. ISBN 9780123846532. | <urn:uuid:f07b79a2-cf28-446d-97df-e4ee8ec2f317> | 3.84375 | 6,943 | Knowledge Article | Science & Tech. | 51.496677 | 95,483,375 |
Presentation on theme: "Meteorology: The Science of the Atmosphere"— Presentation transcript:
1 Meteorology: The Science of the Atmosphere Day 1
2 Characteristics of the Atmosphere 1 OBJ 1: Explain that Earth’s atmosphere is a mixture of particles which are made up of matter. OBJ 2: Describe the composition of the Earth’s atmosphere.Warm-up: Make a list of all the ways the atmosphere is different from outer space.Homework: 1- Review all notes- remember to be ready for a QUIZ at any time! *SF 5 testable questions due 9/10. Science in the News #2 due 9/12Day 1 & 2: ADStand. S Charts how the atmosphere is a mixture of nitrogen, oxygen, and trace amounts of other gases, including water vapor. MDStand. 4.0-A Structure of matter. DO NOT COPY THE FOLLOWING: *Hint: a little more than a century ago, many scientists believed that the Earth’s atmosphere blended with a hypothetical substance called ether that filled the entire universe. In 1887, the physicist A.A. Michelson demonstrated that the universe is not filled with ether.
3 Things to think about…The atmosphere:1. What is it exactly?2. What is its composition?First, let’s revisit OBJ 1:“Explain that Earth’s atmosphere is a mixture of particles which are made up of matter.”Hypothesize. Use OBJ 1 to help you. What key words should we pay attention to?
4 What is the Atmosphere? Air What is air? A gas(es) *Made up of particles or molecules
5 Earth’s atmosphere is… A mixture of gases and other particles that surrounds the Earth*Other particles: solids= dust, ash, sea salt, dirt & smokeLiquids= water and gases = oxygen, carbon dioxide, nitrogen, argon and others
6 Air = Gases and other particles Made up of particles or molecules: *balloonMatterAnything that has mass and takes up space. THINK: solid, liquid, gas or *plasma.e.edu/gchelp/liquids/ character.htmlIs air matter? Yes- has mass and takes up space (balloon). Weigh balloon on triple beam balance. Remember: Mass= how much matter and object has. Space= volume
7 DensityBecause all objects are made out of molecules, it is possible to determined how tightly packed those molecules are. This is known as density. The more tightly packed the molecules of an object, liquid or gas are, the more dense we say they are.DEMO- air pressureThis density of particles helps determines whether an object is a solid, liquid or gas.*balloon
8 However, the density of a gas changes drastically. The density of an object doesn’t change. Or does it? It shows a relationship.WHY?The density of a solid will remain the same no matter where we place the object. For a liquid, density will change only slightly.However, the density of a gas changes drastically.Remember: matter is anything that has mass and takes up space. Density is a measure of the amount of matter in a given space.
9 What gases is the atmosphere composed of? Textbook page 4
11 QuestionWhat do you think the Earth’s atmosphere would be like if plants did not exist?Group Work:Read “How Earth’s Atmosphere Got It’s Oxygen” independentlyIn groups answer questions 1-3
12 Facts to remember! Conclusion The atmosphere is made up of a mixture of atoms & molecules.Air or gases are made up of matter- they have mass and take up space. Think of the BALLOON.Density is the concentration of particles in a given space.Nitrogen is the most abundant gas in the atmosphereEarth’s atmosphere makes conditions on Earth suitable for living things.What is the atmosphere? Name at least three gases the atmosphere is composed of.Conclusion
13 Characteristics of the Atmosphere 3 OBJ 3: Explain how temperature changes with altitude. OBJ 4: Describe the layers of the atmosphere.Warm-up: Which gas- oxygen or nitrogen – is the major component of Earth’s air? Homework: 1- Read & take notes on pgs 3-9 do SR on pg 9. (Notes on the layers of the atmosphere.) 2- Science in the News #2 due 9/12. *Look ahead on SF timeline- what is coming up!!!Day 3. OBJ S : Examines how the atmosphere has different properties at different altitudes.
14 Characteristics of the Atmosphere: Air Pressure What is air pressure?Air pressure:Is the measure of force with which the air molecules push on a surface.*Read the article for HW. DEMO “Air Pressure”(cup of water & cardboard &/or paper towel)High pressure = high density Low pressure = low densityhttps://www.youtube.com/watch?v=goUhGwX-xWohttps://www.youtube.com/watch?v=DZX2mD4voK4
15 3 Factors that affect air pressure AltitudeDensityTemperatureAir PressureWe will discuss the following 3 factors. There are more!
16 Factors: AltitudeAltitude: Height of an object above Earth’s surface.What do you think happens to air molecules as they go up into the atmosphere?Hypothesize! Think about your own experiences- riding on an air plane, hiking up a mountain.
17 Factors: Pressure & Altitude The atmosphere becomes less dense the higher you go away from Earth’s surface -altitude. Atmosphere has weight (pull of gravity). It is the weight of the air above which compresses the air below it to greater density. Air pressure decreases the higher up in the atmosphere you go.The density of the atmosphere: varies with latitude and altitude.
18 Classzone 1901: Pressure & Altitude ntent/visualizations/es1901/es1901page01.cfm?chapter _no=19Classzone 1901: Pressure & AltitudeBalloon demo. *Hopefully this will work on an updated computer!!
19 Factors: TemperatureWhat is temperature? Temperature is the average energy of particles in motion. High temperature means that particles are moving very fast.
20 Factors: Temperature & Water Liquid water: What do you think happens when water evaporates into the atmosphere?
21 Factors: Density What is density? How tightly molecules are packed within a given space.Density = MassVolume
22 Density of Air at Two Altitudes Reminder: what is density? Think about what happens to the gas particles.Use the image on the following slide to answer the following:*Describe the differences in air pressure between points A and B.
23 Density of Air at Two Altitudes At AirLevelA.DensityAt SeaLevelB.
24 Density of a gas A gas will expand to fill the space it is provided. If we take a certain amount of gas out of one container and place it into another container that is twice as large the gas will expand, filling the larger container. We still have the same number of gas molecules, but now, they are filling a much larger area.Thus, the gas is half as denseas it was before. There is twiceas much space between themolecules as there was in thesmaller container.Slide 11- if reinserted in slide show!
25 3 Factors that affect air pressure decreases with an increase inAltitudeDensityincreases withTemperatureAir PressureIs affected by bothaltitude and temperatureWe will discuss the following 3 factors. There are more!AneroidtypesBarometersmeasured withMercury
26 BarometerAn instrument to measure air pressureAneroidMercury
27 Conclusion a.) Name 3 factors that affect air pressure. b.) Explain how temperature changes with altitude.c.) Why does it feel more humid in the summer time?
28 Characteristics of the Atmosphere- 4 OBJ 3 & 4 from yesterday. Warm-up: Have out yesterday’s notes and SR from page 9. While you’re waiting for class to start complete “Layers of the Sky” (OPTION). Homework: Complete Ch. 1 Directed Reading worksheet packet- Due Monday. Science in the News #2 due 9/12Day 4 of atmosphere.
29 Independent Activity- graded CW Agenda:Complete chart: column titled “Major features or characteristics”. (Use your textbook, notes, and partner to help you.)Discuss profile on textbook page 6.Begin reading through tomorrow’s lab: “Layers of the Atmosphere”Begin tonight’s homework- IF time!
30 Profile of Earth's Atmosphere See page 6 of your text. Answer the following.Which layer of the atmosphere is closest to Earth?How does temperature change within the stratosphere?Which atmospheric layer has the greatest range of temperatures?Approximately how thick is the Earth’s atmosphere?What is the iridescent cloud in the thermosphere as seen on page 6?What is the white layer at the top of the stratosphere as seen on page 6?
31 Conclusion Things to think about. Cold air is more dense than warm air. This is an important fact for pilots to know. Why did the Wright brothers test their biplane early in the morning?Apply this logic to the following: Why do people driving jet-powered rocket cars attempt to break the land- speed record at midday on hot salt flats?
32 Layers of the Atmosphere- Day 5 OBJ 3 & 4: Same as yesterday. OBJ S Layers of the Atmosphere- Day 5 OBJ 3 & 4: Same as yesterday. OBJ S Examines how the atmosphere has different properties at different altitudes.Warm-up: none. Turn in SitN #2 in BIN!Homework: 1- Finish “Layers of the Atmosphere”. All Tasks- due Monday. 2- Ch. 1 packet due Monday. QUIZ on is coming! Science in the News #3 due 9/19. *FINAL SF questions are due 9/17.Day 5 atmosphere.
33 AgendaNotes on layers of atmosphere- take out chart. Add notes to “Major features or characteristics”“Layers of the Atmosphere” labTasks 1 & 2Independent time for Tasks 3 & 4 and Chapter 1 packet
34 Layers of the Atmosphere The atmosphere has 4 main layers. Based on your reading what can you tell me about Earth’s atmosphere?Let’s investigate!
35 What layers make up the atmosphere? What is air? What is the atmosphere?
37 http://bedavis. wicomico. wikispaces Does anyone recognize the graph displayed above?!
38 90% of molecules in atmosphere are here, including: almost all of CO2, water vapor, clouds, air pollution, weather, and life. Particles are bumping into one another and therefore transferring energy (IF particles move rapidly but DON’T touch they cannot transfer energy.)
39 Air is thin & has little moisture Air is thin & has little moisture. As altitude increases so does temperature. This is because of ozone (3 oxygen atoms) which absorbs UV radiation, warming air. Ozone- near the top of this layer; protects life at surface.
41 Due to combination of gases, temperature increases with altitude as UV radiation is absorbed. Although temperatures in Thermosphere can reach high temperatures, it may not feel hot. This is because temperature and heat are different.
42 Temperature vs. HeatTemperature is the average energy of particles in motion. High temperature means that particles are moving very fast.Heat is the transfer of energy between objects. In order to transfer energy, particles MUST touch.See textbook page 8
43 Contains charged ions, affects radio waves. See next slide.
44 IonosphereUpper part of mesosphere & lower part of thermosphereNitrogen & Oxygen atoms absorb harmful solar rays (like gamma rays, x-rays)Causes gas particles to become electrically charged (ions)And thus…
45 Aurora BorealisSometimes the ions- charged particles, radiate light energy in the form of different colors. See link.
47 Exosphere Last layer Sits above Thermosphere Border between Earth’s atmosphere and spaceHas no “end” just goes into spaceRegion where atoms and molecules escape into space
48 Layers of the Atmosphere Group work: Complete tasks 1 & 2 in groups.Task 1: Create a temperature profile of the atmosphere. See textbook page 6.Task 2: Graph analysis. See textbook page 6.Task 3: Comparing the Layers of the AtmosphereTask 4: Summary Questions 1-4 Do NOT answer question # 5.
50 Wrap Up Can you anyone name the four major layers of the atmosphere? How can the thermosphere have high temperatures but not feel hot?What are the other three layers we discussed? Describe them.
51 Layers of the Atmosphere- Day 6 OBJ: 5- Summarize the process of radiation, conduction, & convection Warm-up: Turn in Ch. 1 Self Directed packet for section 1 Homework: 1- Read pages 10 – 13. Take notes on “terms to learn” (radiation, conduction, convection, greenhouse effect, and global warming). 2- “Layers of the Atmosphere” lab due tomorrow. 3- Science in the News #3 due 9/19Day 6
52 Agenda Finish notes from yesterday QUIZ Time to finish “Layers of Atmosphere” lab
53 ConclusionAfter completing Task 1 on “Layers of the Atmosphere” what does this graph remind you of?What is the difference between this graph and a profile of Earth’s atmosphere?What is the difference between heat and temperature?
54 Layers of the Atmosphere- Day 7 OBJ: 5- Summarize the process of radiation, conduction, & convection Warm-up: Suppose that you will be vacationing in two unique spots- the Sahara Desert and the Antarctic ice sheet. Decide whether white or black clothing would be best for each location. Explain your choices. Homework: 1- Answer Section Review Question on textbook page Begin working on Ch.1, Sect. 2 Directed Reading Worksheet. 3- Science in the News #3 due 9/19.Day 7
55 Agenda Quiz Continue Task#2 on “Layers of the Atmosphere” Group Activity: Conduction, convection, radiation.You will be put into groups.Each group will be assigned 1 of the ways energy is transferred in the atmosphere.Turn to page 10 & find your assigned term.With your group, determine how you will demonstrate that term using pictures or materials found at home or in the classroom.Each group will present their demonstration to the class.Presentations!
56 Conclusion Answer the following: Describe three (3) things that can happen to energy when it reaches the Earth’s atmosphere.How does the process of convection rely on conduction?
57 Quiz on Section 1 What are the two main gases in Earth’s atmosphere? What is atmospheric pressure?Name the layers of the atmosphere, starting with the one closest to Earth (List ONLY the main 4.)In which layer is the ozone layer located? Why is it important to Earth?What is the difference between heat and temperature?
58 Conclusion- Let’s check your quiz! What are the two main gases in Earth’s atmosphere?What is atmospheric pressure?Name the layers of the atmosphere, starting with the one closest to Earth (List ONLY the main 4.)In which layer is the ozone layer located? Why is it important to Earth?What is the difference between heat and temperature?
59 Layers of the Atmosphere- Day 8/9 OBJ: 5- Summarize the process of radiation, conduction, & convectionWarm-up: Using the terms conduction, convection, and radiation, how is energy transferred throughout the atmosphere? Have out SR from page 13. Be ready to check it! TURN in FINAL SF question in SCIENCE BIN! Homework: Begin/ continue Ch.1, Sect. 2 Directed Reading Worksheet. Science in the News #3 due 9/19.Day 8/9
60 Agenda Continue yesterday’s group work. Presentations Notes Read through Water Coloration labBegin homework
61 Radiation, Conduction, Convection You will be put into groups.Each group will be assigned 1 of the ways energy is transferred in the atmosphere.Turn to page 10 & find your assigned term.With your group, determine how you will demonstrate that term using pictures or materials found at home or in the classroom.Each group will present their demonstration to the class.
62 Radiation Transfer of energy through electromagnetic waves The Earth receives 2 billionths of sun’s energy!!Energy is absorbed by a surface--> surface heats up
63 ConductionTransfer of thermal energy from one material to another by direct contact
64 ConvectionTransfer of thermal energy by the circulation or movement of a liquid or gas. Cool air sinks and warm air rises, thus circulating in a continual process.DENSITY!!Hot air is less dense than cold airCold air is more dense than hot air
65 Conclusion Revisit the following article. How is energy transferred throughout the atmosphere?
66 Layers of the Atmosphere- Day 9 OBJ: 5- Summarize the process of radiation, conduction, & convection Warm-up: none. Have out SR from page 13. Be ready to check it! Homework: Continue Ch.1, Sect. 2 Directed Reading Packet (Start reading text pages so you can complete Sections 3 and 4 of your packet). Science in the News #3 due 9/19.Day 8/9
67 Layers of the Atmosphere- Day 10 OBJ: 5- Summarize the process of radiation, conduction, & convectionWarm-up: Time to meet in your groups. (20 minutes!) TURN in SitN #3 in SCIENCE BIN! Homework: Read and take notes on textbook pages Begin working on Section 3 of your Directed Reading packet (WHOLE packet due Wednesday). Science in the News #4 due 9/26.Day 10
68 AgendaTime to work in your groups- Presentations POSTPONED UNTIL MONDAY!! Be ready to present first thing Monday afternoon!!Begin reading/taking notes on text pages You may begin working on Section 3 in your Directed Reading packet.
69 Conclusion What is a convection current? How does a greenhouse stay warm? Explain.
70 Heating of the Atmosphere- Day 11 OBJ 5: Same as yesterday Heating of the Atmosphere- Day 11 OBJ 5: Same as yesterday. OBJ: 6- Explain how the greenhouse effect could contribute to global warming.Warm-up: Presentations! Homework: Continue working on Ch. 1, Sect. 3 Directed Reading packet- entire packet due Wednesday. Science in the News #4 due 9/26. *QUIZ on Friday.Day 11
71 Agenda Finish demos/ presentations Begin notes on radiation, conduction, & convection (see previous slides: #61-64)Notes on the greenhouse effect and global warming
72 Greenhouse Effect The atmosphere’s trapping of Earth’s thermal energy 50% of radiation that enters the atmosphere is absorbedCarbon dioxide & water vapor stop some of the energy from escaping back into space by absorbing and reradiating itEarth's most abundant greenhouse gases (in order) are:water vaporcarbon dioxideatmospheric methanenitrous oxideozonechlorofluorocarbonsDay 7 and 8
75 Greenhouse Effect Conclusion content/investigations/esu501/esu501page01.cfmConclusionWhat is the greenhouse effect? What specific gases that increase it?
76 Heating of the Atmosphere- Day 12 OBJ 5 and 6 Continued. Warm-up: A metal spoon left in a bowl of hot soup feels hot. Which process-radiation, conduction, or convection- is mainly responsible for heating the spoon?Homework: 1- Greenhouse Effect webquest is due TBA (possibly Monday) 2- Science in the News #4 due 9/26. *QUIZ on Friday. 3- Bibliography of your text book (go toDay 12
77 Agenda Conclusion Why is global warming good for us? Continue greenhouse effect and global warming.Read designated parts of NASA Facts article “Global Warming”Greenhouse effect webquestConclusionWhy is global warming good for us?Why is global warming bad for us?
78 Heating of the Atmosphere- Day 12A OBJ 5 and 6 Continued. Warm-up: none.Agenda: Greenhouse Effect Webquest (answer questions 1-9)Homework: 1- Greenhouse Effect Webquest is due on Friday! 2-Science in the News #4 due 9/26. *QUIZ on Friday.Day 12A
79 TURN in Science in the News #4 Heating of the Atmosphere- Day 13 OBJ 7: Explain the relationship between air pressure and wind direction. OBJ 8: Describe the global pattern of wind. OBJ 9: Explain the causes of local wind patterns.Warm-up: What causes wind?TURN in Science in the News #4Homework: 1- Greenhouse Effect webquest is due on Tuesday. Reread text pages Science in the News #5 due 10/10. *SF DRAFT Bibliography due 10/1.Day 13
80 Agenda QUIZ#1 on OBJECTIVES 1-6. Demo: hot plate and container with iceQuickLab: page 16 “Full of ‘Hot Air’”Notes:What is wind?Pressure BeltsCoriolis Effect
81 What do we know about wind movement? “The wind does blow from high to low”What does this mean?Which area represents low pressure? High pressure?Hypothesize: What do you think will happen and why?Demo
82 QuickLab page 16 Try it at home! What process does this activity model?What do you think will happen if you fill the small bottle with cold water instead?
83 Notes: Wind What is wind? Moving air How is wind created? Created by differences in air pressure.Wind
84 Pressure Belts Warm Air rises over the equator _____ Pressure over the equatorWarm air begins to cool and sinks at around 30 degrees north and 30 degrees south_______ Pressure over 30N and 30SCool air begins to warm and rise at 60 N and 60 S_________ Pressure over 60 N and 60 SConvection Cells
85 What is the Coriolis effect ? The curving of moving objects due to Earth’s rotationWinds curve to the right from the equator in the Northern HemisphereWinds curve to the left from the equator in the Southern Hemisphere
86 Coriolis Effect Conclusion What causes the Coriolis effect? View the animation ES1905How does the Coriolis effect alter wind direction?ConclusionWhat causes wind?How does the Coriolis Effect affect wind movement?Land & Water Lab intro86
87 Heating of Earth's Atmosphere- 14 OBJ 1-9. See previous. Warm-up: Describe the movement of air pressure belts. Homework: Reread pages *SF DRAFT Bibliography due 10/1. Science in the News #5 due 10/10.Day 14
88 Agenda Continue notes- see previous day (Slides #82-85) Demo?! Air pressure websiteDemo?!Conclusion- see previous day
89 Heating of Earth's Atmosphere- 15 OBJ 1-9. See previous. Warm-up: Name the 6 types of wind. Pick one and describe it. Homework: Reread pages 18-19; Study! *SF DRAFT Bibliography due 10/1. Science in the News #5 due 10/10.Day 15
90 Agenda 1. OPTION: Pop quiz- open note book? 2. “Why air moves” 3. Looking at a map4. Types of wind- Global (Notes)
93 Global Winds Trade winds: blow from 30 degrees latitude to the equator Westerlies: wind belts found in both N & S Hemispheres between 30 degrees and 60 degrees latitudePolar Easterlies: extend from poles to 60 degrees latitude in both hemispheresJet Streams: narrow belts of high-speed winds in upper troposphere and lower stratosphere
94 Heating of Earth's Atmosphere- 16 OBJ 1-9. See previous. Warm-up: Can someone demonstrate the Coriolis Effect? Homework: Study! Begin reading/ taking notes on pages Science in the News #5 due 10/10. *SF Draft Hypothesis/ Prediction due 10/8.Day 16
95 Agenda 1. Types of wind- Local Winds: Sea and land breezesMountain and valley breezesSee video:2. Read through Land & Water Land3. Begin lab set up
96 Local Winds Influenced by geography Produces temperature differences Ex. shorelineMountainProduces temperature differencesLand breezeSea breeze(See pages 18-19)
97 ConclusionQuestions on lab??What is a sea breeze? Land breeze?
98 Heating of Earth's Atmosphere- 17 OBJ 1-9. See previous. Warm-up: Begin lab- WAIT FOR INSTRUCTIONS! Homework: Lab due by the end of class tomorrow! Finish reading/ taking notes on pages SF Draft of Hypothesis and Prediction due 10/8. Science in the News #5 due 10/10.***TEST on Ch. 1 on 10/14.Day 17
99 Agenda Conclusion LAB Be sure NOT to violate contract! As warm air rises, it creates an area of ______ pressure over the land. The cool air moves toward the land, producing a ____ __________. Air over the water is cooler and creates an area of ______ pressure.Here, air over land is cooler and creates an area of _____ pressure. The cool air moves toward the water, producing a ____ _________. Air over the water is warmer and creates an area of _____ pressure.Conclusion
100 BE SURE TO TURN IN LAB BEFORE YOU LEAVE CLASS TODAY! The Air We Breather- 18 OBJ 10: Describe the major types of air pollution. OBJ 11: Name the major causes of air pollution OBJ 12: Explain how air pollution can affect human health. OBJ 13: Explain how air pollution can be reduced.Warm-up: See yesterday’s conclusion (complete).BE SURE TO TURN IN LAB BEFORE YOU LEAVE CLASS TODAY!Homework: Answer Section Review on page 19 and 25; Study! SF Draft of Hypothesis and Prediction due 10/8. Science in the News #5 due 10/10. **TEST on 10/14.Day 18
101 Agenda Finish lab NOTES: Air quality: definition Types of air pollutionSources of pollutionEffects on our EarthReducing pollution
102 Air Quality Refers to pollutants in the air Solids, liquids or gasesFrom natural and man made sources:Dust, sea salt, volcanic gases and ash, smoke, pollen, swamp gas*Natural sources produce grater amount of pollutants- BUT we are used to them
103 Types of PollutionPrimary pollutants: go directly into air (from natural & human activity)Secondary pollutants: from chemical reactions between primary pollutantsExample: ozone and smog
104 Sources Human Natural Transportation Industry Indoor Nitrogen cycle CO2 and O2 cycle
105 Effects Reducing Pollution Acid precipitation Ozone hole Effects on human healthClean Air Act- gives EPA authority to regulate air pollutantsReduce, Reuse, RecycleReducing Pollution
106 ConclusionWhat can you do to reduce pollutants?
107 The Air We Breathe- 19 OBJ 1-13. See previous. Warm-up: Continue yesterday’s notes.– WAIT for instructions. Homework: Answer Chapter Review on pages #1- 20; Study! SF Draft of materials, procedures, variables (with plan for analysis) and trials due 10/15. Science in the News #5 due tomorrow. **TEST postponed until 10/15.Day 19
108 Agenda Conclusion OPTIONAL Check SR on 19 and 25 Handout study guide Panel of scientists: research energy source to reduce pollution (Create your own commercial!)In pairs complete Chapter Review on textbook page 30 #1-20Name two primary pollutants.How do secondary pollutants form?OPTIONALConclusion
109 Earth's Atmosphere- 20 OBJ 1-13. See previous. Warm-up: none. TURN in Science in the News #5 Homework: SF Draft of materials, procedures, variables (with plan for analysis) and trials due 10/15. Science in the News #6 due 10/17. Study! **TEST changed to 10/15.Day 20
110 TEST talk Conclusion Let’s prepare together! Complete #21-24 and in small groupsAny questions!!??!!Conclusion
111 Test talk. Agenda:. answer any last questions. before test Test talk! Agenda: * answer any last questions before test * turn in MPTV *Lab (?) *begin our next chapter
112 TEST is Today!- 21Homework: Read and take notes on pages (take GOOD notes). Science in the News #6 due 10/17. SF Draft Background Research due 11/5.Day 21 | <urn:uuid:f02eeae6-77fe-4d92-89a0-a1f82f3886a2> | 3.625 | 6,229 | Tutorial | Science & Tech. | 62.554217 | 95,483,376 |
Locating a Drilling Site on the Patagonian Icefields
Locating a suitable drill site involves a number of compromises. At the proper place, an ice core can provide a record of climate changes in the past. Also, everything that has precipitated on the ice cap will be preserved, including biological fall out. At cold places, even gases are preserved in the bubbles in the ice, or in the ice lattice. In fact the ice cap can be considered as a long-term storage of both climatological and environmental information. In order to retrieve the information, an ice core has to be drilled. The site where the core is drilled determines the information that can be obtained. At a high accumulation site, it may be possible to obtain information at time scales of a fraction of a year. At a site with less accumulation, it may be possible to obtain records going further back in time. Summer melting obliterates the signals from the ice core, and for most studies summer melting should be minimized. The best drilling site therefore depends on the purpose of the drilling.
KeywordsDrilling Site Climate Change Study Bedrock Topography Flight Plan High Frequency Radar
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- Aristarain, A. J., and Delmas, R. J., 1993, Firn-core study from the Southern Patagonia ice cap, South America, Journal of Glaciology, 39(132):249–254.Google Scholar
- Benn, D. I., and Evans, D. J. A., 1998, Glaciers and Glaciation, Arnold, ISBN 0 340 58431, Figure 1.18, Plate 4.Google Scholar
- Damm, V., and Casassa, G., 1999, Glaciological and hydrogeological studies of glaciers in central Chile and Patagonia using a helicopter borne radio echo soundings system. Operational report and preliminary results, Archiv-Nr. 0119119, Bundesanstalt fur Geowissenschaften and Rohstoffe, Hannover, Germany, pp. 34.Google Scholar
- Godoi, M. A., Shiraiwa, T., Kohshima, S., and Kubota, K., 2002, Firn-core drilling operation at Tyndall Glacier, Southern Patagonia Icefield, in: The Patagonian kefields: a unique natural laboratory for environmental and climate change studies, G. Casassa, F. V. Septúlveda, and R. M. Sinclair, eds., Kluwer Academic/Plenum Publishers, New York, pp. 149–156.Google Scholar
- Gundestrup, N. S., Bindschadler, R. A., and Zwally, H. J., 1986, Seasat range measurements verified on a 3-D ice sheet, Annals of Glaciology, 8:69–72.Google Scholar
- Paterson, W. S. B., 1994, The Physics of Glaciers, 3rd edition, Elsevier, ISBN 0–08–037945.Google Scholar
- Rivera, A., and Casassa G., 2002, Ice thickness measurements on the Southern Patagonia Icefield, in: The Patagonian lcefields: a unique natural laboratory for environmental and climate change studies, G. Casassa, F. V. Sepúlveda, and R. M. Sinclair, eds., Kluwer Academic/Plenum Publishers, New York, pp. 101–115.Google Scholar | <urn:uuid:5b745ca1-0464-41ba-a67a-db26ad376067> | 3 | 728 | Academic Writing | Science & Tech. | 56.478936 | 95,483,391 |
Ultrahigh Sensitivity Detection System for Far Infrared Spectrophotometers
The problems of detection in far infrared grating spectrophotometers can generally be related to several factors: (1) low intensity of available radiation from the source, (2) energy loss due to the filters which are necessary for blocking of unwanted radiation, (3) only a narrow band of energy (the resolution width) available to the detector in a given time increment, (4) inefficiencies in the optical train, and (5) detector characteristics such as sensitivity to incident radiation and inherent noise fluctuations. Some of these problems can be solved in part by careful design of filters and optics. However, even in the case of a nearly perfect optical train the detector sensitivity becomes the limiting factor, and large improvements can be made only by cooling the detector to low temperatures and reducing the background radiation seen by the detector. The low temperature germanium bolometer detector developed by Low1 is several hundred to several thousand times more sensitive than uncooled detectors, depending on the incident background level, and, properly coupled to the spectrophotometer optical train, offers the possibility of greatly enhancing the performance of far infrared instruments.
KeywordsNoise Equivalent Power Infrared Fourier Transform Spectroscopy Sample Beam Fourier Transform Spectroscopy Mercuric Oxide4
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Geographers at Jena University use satellite and terrestrial data to calculate aboveground biomass in South Africa’s Kruger National Park
Savannahs form one of the largest habitats in the world, covering around one-fifth of the Earth’s land area. They are mainly to be found in sub-Saharan Africa. Savannahs are home not only to unique wildlife, including the ‘Big Five’ – the African elephant, rhinoceros, Cape buffalo, leopard and lion – but also to thousands of endemic plant species such as the baobab, or monkey bread tree.
“What’s more, the savannahs play a significant role in the global carbon cycle and therefore affect the planet’s climate cycles,” says Victor Odipo of Friedrich Schiller University, Jena (Germany). The ability of the savannahs to store the greenhouse gas carbon dioxide is ultimately determined by the amount of aboveground woody biomass, adds Odipo, a doctoral candidate at the Institute of Geography’s Remote Sensing section.
So far, though, it has been difficult to measure this important indicator, with current climate models relying on rough carbon estimates. However, a team of geographers from the universities of Jena and Oxford, and from Germany’s Federal Institute for Geosciences and Natural Resources, has now succeeded in establishing a methodology that enables them to measure the aboveground biomass of the savannahs and record even minor changes in the ecosystem. They have presented their results in the specialist journal ‘Forests’ (DOI: 10.3390/f7120294).
Three-dimensional model of the landscape
The researchers from the University of Jena use both radar data recorded by satellites and laser scanning data collected from the ground. “Radar data can record the biomass over larger geographical areas, given its coverage, but it provides insufficient information about the structure of the vegetation at localised scales,” explains Victor Odipo. Typical of the savannah is its patchwork-like structure: a mixture of grass and shrubs with trees of very different heights, either standing alone or in patches.
In order to make a detailed record of this structure and be able to convert it into biomass, the satellite data is complemented by ground-based measurements. For this purpose, a terrestrial laser scanner (TLS) is used, which scans its surroundings with a laser beam within a radius of several hundred metres. “This provides us with a comprehensive three-dimensional digital model of the landscape, which enables a precise analysis of the vegetation structure,” says Jussi Baade, associate professor of Physical Geography at the University of Jena.
After exhaustive initial tests in the Stadtrodaer Forest and the slopes of the Saale valley near Jena, the researchers have now applied their methodology to the savannah of Kruger National Park in South Africa. In an area of some nine square kilometres for which radar satellite data is available, they collected laser scanning data from more than 40 plots, and integrated this data into a model for calculating the biomass.
“The laser scanning data collected from selected points does give significantly more precise results than the satellite radar,” notes Christian Berger, co-author of the study and head of the research project on which Victor Odipo’s doctoral thesis is based. “But on its own, and due to smaller coverage compared with airborne data, this method is not suitable for investigating large areas.” As this study shows, however, combining the two methods allows estimation of biomass with a range of 2.9 tonnes per hectare in areas of grass and shrubs to 101.6 tonnes per hectare in areas with trees.
Monitoring changes in the ecosystem
These results cannot be used to create new climate models. “We also need reliable data to monitor changes in the savannah ecosystem,” says Victor Odipo. He points to a surprising incidental find: the researchers’ measurements showed that the biomass of a substantial part of the study area in Kruger National Park is declining from year to year. “We didn’t expect that,” says Odipo, “given that this is a nature reserve.” It turned out, however, that these changes – unlike those in most unprotected areas – were not primarily the result of human activity, but rather the work of elephants, which bring down a large number of trees.
This study was supported by the German Academic Exchange Service (DAAD), the German Research Foundation (DFG), and the Federal Ministry of Education and Research (BMBF). The terrestrial laser scanner was acquired with the help of EFRD funds from the Free State of Thuringia.
Odipo VO et al. Assessment of Aboveground Woody Biomass Dynamics Using Terrestrial Laser Scanner and L-Band ALOS PALSAR Data in South African Savanna, Forests; DOI:10.3390/f7120294
Victor Odipo, Prof. Christiane Schmullius
Institute of Geography of Friedrich Schiller University, Jena
Grietgasse 6, 07743 Jena, Germany
Phone: +49 (0)3641 / 948895, +49 (0)3641 / 948880
E-mail: victor.onyango[at]uni-jena.de, c.schmullius[at]uni-jena.de
Dr. Ute Schönfelder | idw - Informationsdienst Wissenschaft
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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20.07.2018 | Materials Sciences | <urn:uuid:e63b16bb-0c51-4e06-add9-3f4d0282e992> | 3.765625 | 1,735 | Knowledge Article | Science & Tech. | 36.340736 | 95,483,419 |
During the middle of 2013, Jupiter’s moon Io came alive with volcanism. Now, an image from the Gemini Observatory captures what is one of the brightest volcanoes ever seen in our solar system.
The image, obtained on August 29, reveals the magnitude of the eruption that was the “grand finale” in a series of eruptions on the distant moon. Io’s volcanism is caused by the tidal push-and-pull of massive Jupiter, which heats the satellite’s interior – making it our Solar System’s most volcanically active known body.
Figure 1. Image of Io taken in the near-infrared with adaptive optics at the Gemini North telescope on August 29. In addition to the extremely bright eruption on the upper right limb of the satellite, the lava lake Loki is visible in the middle of Io’s disk, as well as the fading eruption that was detected earlier in the month by de Pater on the southern (bottom) limb. Io is about one arcsecond across. Image credit: Katherine de Kleer/UC Berkeley/Gemini Observatory/AURA
Figure 2. Images of Io taken in the near-infrared with adaptive optics at the Gemini North telescope tracking the evolution of the eruption as it decreased in intensity over 12 days. Due to Io’s rapid rotation, a different area of the surface is viewed on each night; the outburst is visible with diminishing brightness on August 29 & 30 and September 1, 3, & 10. Image credit: Katherine de Kleer/UC Berkeley/Gemini Observatory/AURA
According to University of California Berkeley (UCB) astronomer Katherine de Kleer, the Gemini observations, “… represent the best day-by-day coverage of such an eruption – thanks to Gemini’s rapid and flexible scheduling capabilities.” De Kleer, who led one of a pair of two papers published today in the journal Icarus, adds that the Gemini data allowed the team to monitor the evolution of the extreme volcanic activity over nearly the first two weeks of the eruption – which provided a critical new perspective on the outburst events.
De Kleer’s paper examines the powerful late-August eruption in detail, concluding that the energy emitted was about 20 Terawatts and expelled many cubic kilometers of lava. “At the time we observed the event, an area of newly-exposed lava on the order of tens of square kilometers was visible” says de Kleer. “We believe that it erupted in fountains from long fissures on Io’s surface, which were over ten-thousand-times more powerful than the lava fountains during the 2010 eruption of Eyjafjallajokull, Iceland, for example.”
The original detection of the volcano was made simultaneously at Gemini and NASA’s Infrared Telescope Facility (IRTF), and was the first of a series of observations monitoring Io at both facilities over the following year. These particular observations were timed to follow up on a different outburst eruption that was detected earlier in the month by Imke de Pater, also of UCB.
This record of the spate of activity began when de Pater first spotted a hotspot using the W.M. Keck Observatory in mid-August (see UCB press release, also released today at: http://newscenter.berkeley.edu/2014/08/04/a-hellacious-two-weeks-on-jupiters-moon-io/), which the team followed with further observations from Mauna Kea. The late August Gemini observations of the most extreme outburst (see Figure 1) used adaptive optics on the Gemini North telescope to produce this super-sharp near-infrared image. Gemini also recorded a series of images chronicling the massive eruption’s evolution as it faded over the next 12 days (see Figure 2).
In addition to de Kleer and de Pater, the lead authors on the two publications discussing these events, the research team included Máté Ádámkovics of UCB, Ashley Davies from the Jet Propulsion Laboratory and David Ciardi of Caltech's NASA Exoplanet Science Institute. The work is funded by the National Science Foundation and NASA’s Outer Planets Research and Planetary Geology and Geophysics Program.
The papers are available in the journal Icarus (subscription required).
Public Information and Outreach Manager
Gemini Observatory, Hilo, HI
Cell: (808) 936-6643
Desk: (808) 974-2510
Katherine de Kleer
University of California Berkeley
Imke de Pater
University of California Berkeley
Peter Michaud | Eurek Alert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
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using standard courier delivery
While examining the history of our planet and actively exploring our present environment, science journalist Michael Tennesen describes what life on earth could look like after the next mass extinction. A growing number of scientists agree we are headed toward a mass extinction, perhaps in as little as 300 years. Already there have been five mass extinctions in the last 600 million years, including the Cretaceous Extinction, during which an asteroid knocked out the dinosaurs. Though these events were initially destructive, they were also prime movers of evolutionary change in nature. And we can see some of the warning signs of another extinction event coming, as our oceans lose both fish and oxygen. In The Next Species, Michael Tennesen questions what life might be like after it happens. Tennesen discusses the future of nature and whether humans will make it through the bottleneck of extinction. Without man, could the seas regenerate to what they were before fishing vessels? Could life suddenly get very big as it did before the arrival of humans? And what if man survives the coming catastrophes, but in reduced populations? Would those groups be isolated enough to become distinct species? Could the conquest of Mars lead to another form of human? Could we upload our minds into a computer and live in a virtual reality? Or could genetic engineering create a more intelligent and long-lived creature that might shun the rest of us? And how would we recognize the next humans? Are they with us now? Tennesen delves into the history of the planet and travels to rainforests, canyons, craters, and caves all over the world to explore the potential winners and losers of the next era of evolution. His predictions, based on reports and interviews with top scientists, have vital implications for life on earth today. | <urn:uuid:0bccf7e1-927b-47cc-908b-5fb9e1cb1c4b> | 3.5625 | 361 | Product Page | Science & Tech. | 41.944706 | 95,483,421 |
Infrared observations by the Hubble Space Telescope reveal jets from a forming star.
We receive a lot of press releases here at Sky & Telescope. They span a wide range of interest and quality. This week, a delightful treat popped into our inboxes, in the form of this press release from the Hubble folks. We enjoyed it so much that we decided to post it here for your reading pleasure. Hats off to the public information officers who put this together.
Or, as our editor in chief put it: may the farce be with you.
The Awakened Force of a Star
Perfectly timed for the release of Star Wars Episode VII: The Force Awakens, the NASA/ESA Hubble Space Telescope has imaged a cosmic double-bladed lightsaber. In the center of the image, partially obscured by a dark Jedi-like cloak of dust, an adolescent star shoots twin jets out into space, demonstrating the fearsome forces of the universe.
This celestial lightsaber lies not in a galaxy far, far away, but within our home galaxy, the Milky Way. More precisely, it resides within a turbulent patch of space known as the Orion B molecular cloud complex, which is located just over 1,350 light-years away in the constellation of Orion the Hunter.
Bearing a striking resemblance to Darth Maul’s double-bladed lightsaber in Star Wars Episode One, the spectacular twin jets of material slicing across this incredible image are spewing out from a newly formed star that is obscured from view, cloaked by swirling dust and gas.
When stars form within giant, gaseous clouds, some of the surrounding material collapses down to form a rotating, flattened disc encircling the nascent stars, which are known as protostars. This disc is where a potential planetary system might form. However, at this early stage, the star is mostly concerned with feeding its Jabba-like appetite. Gas from the disc rains down onto the protostar and, once nourished, the star awakens and jets of energized gas from its poles whirl out in opposite directions.
The Force is strong with these twin jets; their effect on their environment demonstrates the true power of the Dark Side with a blast stronger than one from a fully armed and operational Death Star battle station. As they stream away from one another at high speeds, supersonic shock fronts develop along the jets and heat the surrounding gas to thousands of degrees.
Furthermore, as the jets collide with the surrounding gas and dust and clear vast spaces, they create curved shock waves. These shock waves are the hallmarks of Herbig-Haro (HH) objects — tangled, knotted clumps of nebulosity. The prominent Herbig-Haro object shown in this image is HH 24.
Just to the right of the cloaked star, a couple of bright points of light can be seen. These are young stars peeking through and showing off their own faint lightsabers. One hidden, cloaked source, only detectable in the radio part of the spectrum, has blasted a tunnel through the dark cloud in the upper left of the image with a wider outflow resembling “force lightning.”
All these jets make HH 24 the densest concentration of HH jets known in such a small region. Half of the HH jets have been spotted in this region in visible light, and about the same number in the infrared. Hubble’s observations for this image were performed in infrared light, which enabled the telescope to pierce through the gas and dust cocooning the newly-forming stars and capture a clear view of the HH objects that astronomers are looking for.
A slightly different version of this press release appears on the Space Telescope Science Institute website.
Below, you'll find a 3D simulated video zooming in on HH 24. Credit: NASA / ESA / G. Bacon / L. Frattare / Z. Levay / F. Summers (Viz 3D Team, STScI)
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The editors present a state-of-the-art overview on the Physics of Space Weather and its effects on technological and biological systems on the ground and in space. It opens with a general introduction on the subject, followed by a historical review on the major developments in the field of solar terrestrial relationships leading to its development into the up-to-date field of space weather. Specific emphasis is placed on the technological effects that have impacted society in the past century at times of major solar activity. Chapter 2 summarizes key milestones, starting from the base of solar observations with classic telescopes up to recent space observations and new mission developments with EUV and X-ray telescopes (e.g., STEREO), yielding an unprecedented view of the sun-earth system. Chapter 3 provides a scientific summary of the present understanding of the physics of the sun-earth system based on the latest results from spacecraft designed to observe the Sun, the interplanetary medium and geospace. Chapter 4 describes how the plasma and magnetic field structure of the earth's magnetosphere is impacted by the variation of the solar and interplanetary conditions, providing the necessary science and technology background for missions in low and near earth's orbit. Chapter 5 elaborates the physics of the layer of the earth's upper atmosphere that is the cause of disruptions in radio-wave communications and GPS (Global Positioning System) errors, which is of crucial importance for projects like Galileo. In Chapters 6-10, the impacts of technology used up to now in space, on earth and on life are reviewed.
Publisher: Springer-Verlag Berlin and Heidelberg GmbH & Co. KG
Number of pages: 438
Weight: 2690 g
Dimensions: 242 x 170 x 28 mm
Edition: 2007 ed.
From the reviews:
"The volume surveys the broad expanse of space weather through 14 chapters contributed by 20 expert practitioners. ... its extensive reference lists at the end of each chapter are extremely valuable. I believe the book functions best by sitting on the library reference shelf where it can be readily consulted as needed." (Thomas J. Bogdan, Physics Today, December 2007)
"Space Weather: Physics and Effects is an attempt to summarize the entire field of space weather. ... It is generally well produced, includes an exhaustive table of contents and has nearly 40 pages of prefatory materials including a four-page list of acronyms, and what seems like an adequate index." (W. Jeffrey Hughes, EOS, March, 2009)
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Arrange the four number cards on the grid, according to the rules, to make a diagonal, vertical or horizontal line.
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?
Mr McGregor has a magic potting shed. Overnight, the number of plants in it doubles. He'd like to put the same number of plants in each of three gardens, planting one garden each day. Can he do it?
Sitting around a table are three girls and three boys. Use the clues to work out were each person is sitting.
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?
The planet of Vuvv has seven moons. Can you work out how long it is between each super-eclipse?
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.
What happens when you add three numbers together? Will your answer be odd or even? How do you know?
Sweets are given out to party-goers in a particular way. Investigate the total number of sweets received by people sitting in different positions.
Investigate the different numbers of people and rats there could have been if you know how many legs there are altogether!
Can you make square numbers by adding two prime numbers together?
The Zargoes use almost the same alphabet as English. What does this birthday message say?
A student in a maths class was trying to get some information from her teacher. She was given some clues and then the teacher ended by saying, "Well, how old are they?"
This challenge focuses on finding the sum and difference of pairs of two-digit numbers.
Use the clues to work out which cities Mohamed, Sheng, Tanya and Bharat live in.
Find the sum and difference between a pair of two-digit numbers. Now find the sum and difference between the sum and difference! What happens?
Six friends sat around a circular table. Can you work out from the information who sat where and what their profession were?
When newspaper pages get separated at home we have to try to sort them out and get things in the correct order. How many ways can we arrange these pages so that the numbering may be different?
What is the smallest number of jumps needed before the white rabbits and the grey rabbits can continue along their path?
Only one side of a two-slice toaster is working. What is the quickest way to toast both sides of three slices of bread?
Can you create jigsaw pieces which are based on a square shape, with at least one peg and one hole?
This tricky challenge asks you to find ways of going across rectangles, going through exactly ten squares.
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?
How many ways can you find to do up all four buttons on my coat? How about if I had five buttons? Six ...?
These activities lend themselves to systematic working in the sense that it helps if you have an ordered approach.
Use the clues to find out who's who in the family, to fill in the family tree and to find out which of the family members are mathematicians and which are not.
Given the products of adjacent cells, can you complete this Sudoku?
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?
If you take a three by three square on a 1-10 addition square and multiply the diagonally opposite numbers together, what is the difference between these products. Why?
Can you put the numbers 1-5 in the V shape so that both 'arms' have the same total?
An investigation that gives you the opportunity to make and justify predictions.
This challenge, written for the Young Mathematicians' Award, invites you to explore 'centred squares'.
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?
Make a pair of cubes that can be moved to show all the days of the month from the 1st to the 31st.
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?
These activities focus on finding all possible solutions so if you work in a systematic way, you won't leave any out.
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.
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?
Can you fill in this table square? The numbers 2 -12 were used to generate it with just one number used twice.
These activities focus on finding all possible solutions so working in a systematic way will ensure none are left out.
If we had 16 light bars which digital numbers could we make? How will you know you've found them all?
These are the faces of Will, Lil, Bill, Phil and Jill. Use the clues to work out which name goes with each face.
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?
These activities lend themselves to systematic working in the sense that it helps to have an ordered approach.
This task follows on from Build it Up and takes the ideas into three dimensions!
Can you find all the ways to get 15 at the top of this triangle of numbers? Many opportunities to work in different ways.
The challenge here is to find as many routes as you can for a fence to go so that this town is divided up into two halves, each with 8 blocks.
Follow the clues to find the mystery number.
If you have three circular objects, you could arrange them so that they are separate, touching, overlapping or inside each other. Can you investigate all the different possibilities? | <urn:uuid:4d4c7fce-4d05-4e96-8d49-b973dd4661e1> | 3.421875 | 1,400 | Content Listing | Science & Tech. | 66.350089 | 95,483,430 |
Changes in sedimentary diagenetic processes resulting from the transition from a terrestrial to a marine environment were studied through a series of riverbed cores collected from the White Oak River Estuary. Analyses of interstitial water and associated solid phases reveal systematic geochemical and mineralogical trends over an 18-km stretch of estuary and river channel related to the transition from a dominantly marine to a dominantly terrestrial setting. The most striking of these trends involves the nature of the metabolic pathways by which bacterial decomposition of organic matter occurs and probable differences in the composition of organic matter. In the riverbed stretches under periodic marine influence, sulfate reduction is a major process, owing to the availability of seawater sulfate. Upstream, however, methane generation becomes more important. Consistent with this trend is a decrease in sedimentary pyrite in methane-rich sediments. Total inorganic carbon decreases by nearly an order of magnitude upstream, and pH is significantly lower in the terrestrial environment. Chemically reactive products of organic decomposition, such as ammonia and phosphate, are considerably less concentrated in the cores taken farthest from marine influence.
Mendeley saves you time finding and organizing research
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Three years ago, when CRISPR-Cas9, a method of precisely editing DNA, suddenly appeared liked a technology from the future, scientists realized we could now engineer the human race by giving our children and their heirs improved genes. But many disavowed that we would do so soon.
The biologist Weizhi Ji, who created two gene-edited macaque monkeys at Kunming Biomedical International, said that creating humans with CRISPR-edited genomes was “very possible,” but added that “considering the safety issue, there would still be a long way to go.” (See “10 Breakthrough Technologies: Genome Editing.”)
Yet I was sure that scientists would research how to edit the human germ line, and quickly. (“Germ line” is biologists’ jargon for the egg and the sperm, which combine to form an embryo. Editing the DNA of such cells, or of the embryo itself, would pass heritable changes to future generations.)
They would try because editing genes with CRISPR was trivially easy, and it would be a sensational thing to do. “Any scientist with molecular biology skills and knowledge of how to work with [embryos] is going to be able to do this,” says Jennifer Doudna, a biologist at the University of California, Berkeley, who in 2012 co-discovered how to use CRISPR to edit genes.
Mostly, they would research CRISPR because it seems a powerful way to prevent disease from birth. Guoping Feng, a neurobiologist at MIT’s McGovern Institute for Brain Research, believes that gene-edited human beings are “10 to 20 years away,” but nonetheless approves of human germ-line editing. Feng says, “To me, it’s possible in the long run to dramatically improve health, lower costs. It’s a kind of prevention.”
Why not use CRISPR to eliminate diseases like Huntington’s, a terrible, fatal neurodegenerative disorder triggered by a defect in a single gene? Or why not correct the DNA of an embryo with a mutation in a gene called BRCA1, which causes ovarian and breast cancer? While you’re fiddling with an embryo’s DNA, why not insert naturally occurring gene variants that confer extraordinary characteristics like unbreakable bones or resistance to diseases like Alzheimer’s?
As our biomedicine editor, Antonio Regalado, reports in this issue’s cover story, “Engineering the Perfect Baby,” experiments designed to correct the DNA in a woman’s egg or a man’s sperm, or to directly edit the DNA of an early-stage embryo using CRISPR, are already being carried out.
Why not? One concern is that the technologies would not be widely available, at least at first. Their expense would mean only rich people would have perfect children. Another worry is that germ-line engineering would affect unborn people without their consent. The most potent objection is that we don’t know what we’re doing: if you provide immunity to a disease, you might break something in a genome.
History insists that when a technology has obvious utility, it will be used. But how we use a new technology is our choice. In March, writing in the journal Science, a group of scientists including Doudna and two Nobel laureates called for a great debate on the genetic engineering of humans and a moratorium on any effort to create engineered babies. Crucially, the scientists did not ask their peers to stop using CRISPR to edit human embryos for research purposes; but they recommended convening a “globally representative” group of government agencies, ethics experts, and scientists to suggest policies to guide that research.
Let’s have that debate. Write to me at firstname.lastname@example.org.
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Tidal force(Redirected from Tidal forces)
The tidal force is an apparent force that stretches a body towards the center of mass of another body due to a gradient (difference in strength) in gravitational field from the other body; it is responsible for diverse phenomena, including tides, tidal locking, breaking apart of celestial bodies and formation of ring systems within Roche limit, and in extreme cases, spaghettification of objects. It arises because the gravitational force exerted on one body by another is not constant across its parts: the nearest side is attracted more strongly than the farthest side. It is this difference that causes a body to get stretched. Thus, the tidal force is also known as the differential force, as well as a secondary effect of the gravitational force.
In celestial mechanics, the expression "tidal force" can refer to a situation in which a body or material (for example, tidal water) is mainly under the gravitational influence of a second body (for example, the Earth), but is also perturbed by the gravitational effects of a third body (for example, the Moon). The perturbing force is sometimes in such cases called a tidal force (for example, the perturbing force on the Moon): it is the difference between the force exerted by the third body on the second and the force exerted by the third body on the first.
When a body (body 1) is acted on by the gravity of another body (body 2), the field can vary significantly on body 1 between the side of the body facing body 2 and the side facing away from body 2. Figure 2 shows the differential force of gravity on a spherical body (body 1) exerted by another body (body 2). These so-called tidal forces cause strains on both bodies and may distort them or even, in extreme cases, break one or the other apart. The Roche limit is the distance from a planet at which tidal effects would cause an object to disintegrate because the differential force of gravity from the planet overcomes the attraction of the parts of the object for one another. These strains would not occur if the gravitational field were uniform, because a uniform field only causes the entire body to accelerate together in the same direction and at the same rate.
Effects of tidal forcesEdit
In the case of an infinitesimally small elastic sphere, the effect of a tidal force is to distort the shape of the body without any change in volume. The sphere becomes an ellipsoid with two bulges, pointing towards and away from the other body. Larger objects distort into an ovoid, and are slightly compressed, which is what happens to the Earth's oceans under the action of the Moon. The Earth and Moon rotate about their common center of mass or barycenter, and their gravitational attraction provides the centripetal force necessary to maintain this motion. To an observer on the Earth, very close to this barycenter, the situation is one of the Earth as body 1 acted upon by the gravity of the Moon as body 2. All parts of the Earth are subject to the Moon's gravitational forces, causing the water in the oceans to redistribute, forming bulges on the sides near the Moon and far from the Moon.
When a body rotates while subject to tidal forces, internal friction results in the gradual dissipation of its rotational kinetic energy as heat. In the case for the Earth, and Earth's Moon, the loss of rotational kinetic energy results in a gain of about 2 milliseconds per century. If the body is close enough to its primary, this can result in a rotation which is tidally locked to the orbital motion, as in the case of the Earth's moon. Tidal heating produces dramatic volcanic effects on Jupiter's moon Io. Stresses caused by tidal forces also cause a regular monthly pattern of moonquakes on Earth's Moon.
Tidal forces contribute to ocean currents, which moderate global temperatures by transporting heat energy toward the poles. It has been suggested that in addition to other factors, harmonic beat variations in tidal forcing may contribute to climate changes. However, no strong link has been found to date.
Tidal effects become particularly pronounced near small bodies of high mass, such as neutron stars or black holes, where they are responsible for the "spaghettification" of infalling matter. Tidal forces create the oceanic tide of Earth's oceans, where the attracting bodies are the Moon and, to a lesser extent, the Sun. Tidal forces are also responsible for tidal locking, tidal acceleration, and tidal heating. Tides may also induce seismicity.
For a given (externally generated) gravitational field, the tidal acceleration at a point with respect to a body is obtained by vectorially subtracting the gravitational acceleration at the center of the body (due to the given externally generated field) from the gravitational acceleration (due to the same field) at the given point. Correspondingly, the term tidal force is used to describe the forces due to tidal acceleration. Note that for these purposes the only gravitational field considered is the external one; the gravitational field of the body (as shown in the graphic) is not relevant. (In other words, the comparison is with the conditions at the given point as they would be if there were no externally generated field acting unequally at the given point and at the center of the reference body. The externally generated field is usually that produced by a perturbing third body, often the Sun or the Moon in the frequent example-cases of points on or above the Earth's surface in a geocentric reference frame.)
Tidal acceleration does not require rotation or orbiting bodies; for example, the body may be freefalling in a straight line under the influence of a gravitational field while still being influenced by (changing) tidal acceleration.
By Newton's law of universal gravitation and laws of motion, a body of mass m at distance R from the center of a sphere of mass M feels a force ,
equivalent to an acceleration ,
where is a unit vector pointing from the body M to the body m (here, acceleration from m towards M has negative sign).
Consider now the acceleration due to the sphere of mass M experienced by a particle in the vicinity of the body of mass m. With R as the distance from the center of M to the center of m, let ∆r be the (relatively small) distance of the particle from the center of the body of mass m. For simplicity, distances are first considered only in the direction pointing towards or away from the sphere of mass M. If the body of mass m is itself a sphere of radius ∆r, then the new particle considered may be located on its surface, at a distance (R ± ∆r) from the centre of the sphere of mass M, and ∆r may be taken as positive where the particle's distance from M is greater than R. Leaving aside whatever gravitational acceleration may be experienced by the particle towards m on account of m's own mass, we have the acceleration on the particle due to gravitational force towards M as:
Pulling out the R2 term from the denominator gives:
The Maclaurin series of is which gives a series expansion of:
The first term is the gravitational acceleration due to M at the center of the reference body , i.e., at the point where is zero. This term does not affect the observed acceleration of particles on the surface of m because with respect to M, m (and everything on its surface) is in free fall. When the force on the far particle is subtracted from the force on the near particle, this first term cancels, as do all other even-order terms. The remaining (residual) terms represent the difference mentioned above and are tidal force (acceleration) terms. When ∆r is small compared to R, the terms after the first residual term are very small and can be neglected, giving the approximate tidal acceleration (axial) for the distances ∆r considered, along the axis joining the centers of m and M:
When calculated in this way for the case where ∆r is a distance along the axis joining the centers of m and M, is directed outwards from to the center of m (where ∆r is zero).
Tidal accelerations can also be calculated away from the axis connecting the bodies m and M, requiring a vector calculation. In the plane perpendicular to that axis, the tidal acceleration is directed inwards (towards the center where ∆r is zero), and its magnitude is (axial) in linear approximation as in Figure 2.
The tidal accelerations at the surfaces of planets in the Solar System are generally very small. For example, the lunar tidal acceleration at the Earth's surface along the Moon-Earth axis is about 1.1 × 10−7 g, while the solar tidal acceleration at the Earth's surface along the Sun-Earth axis is about 0.52 × 10−7 g, where g is the gravitational acceleration at the Earth's surface. Hence the tide-raising force (acceleration) due to the Sun is about 45% of that due to the Moon. The solar tidal acceleration at the Earth's surface was first given by Newton in the Principia.
- "On the tidal force", I. N. Avsiuk, in "Soviet Astronomy Letters", vol. 3 (1977), pp. 96–99.
- See p. 509 in "Astronomy: a physical perspective", M. L. Kutner (2003).
- R Penrose (1999). The Emperor's New Mind: Concerning Computers, Minds, and the Laws of Physics. Oxford University Press. p. 264. ISBN 0-19-286198-0.
- Thérèse Encrenaz; J -P Bibring; M Blanc (2003). The Solar System. Springer. p. 16. ISBN 3-540-00241-3.
- R. S. MacKay; J. D. Meiss (1987). Hamiltonian Dynamical Systems: A Reprint Selection. CRC Press. p. 36. ISBN 0-85274-205-3.
- Rollin A Harris (1920). The Encyclopedia Americana: A Library of Universal Knowledge. 26. Encyclopedia Americana Corp. pp. 611–617.
- "The Tidal Force | Neil deGrasse Tyson". www.haydenplanetarium.org. Retrieved 2016-10-10.
- "Millennial Climate Variability: Is There a Tidal Connection?".
- "Hungry for Power in Space". New Scientist. New Science Pub. 123: 52. 23 September 1989. Retrieved 14 March 2016.
- "Inseparable galactic twins". ESA/Hubble Picture of the Week. Retrieved 12 July 2013.
- The Admiralty (1987). Admiralty manual of navigation. 1. The Stationery Office. p. 277. ISBN 0-11-772880-2., Chapter 11, p. 277
- Newton, Isaac (1729). The mathematical principles of natural philosophy. 2. p. 307. ISBN 0-11-772880-2., Book 3, Proposition 36, Page 307 Newton put the force to depress the sea at places 90 degrees distant from the Sun at "1 to 38604600" (in terms of g), and wrote that the force to raise the sea along the Sun-Earth axis is "twice as great", i.e. 2 to 38604600, which comes to about 0.52 × 10−7 g as expressed in the text.
- Gravitational Tides by J. Christopher Mihos of Case Western Reserve University
- Audio: Cain/Gay – Astronomy Cast Tidal Forces – July 2007.
- Gray, Meghan; Merrifield, Michael. "Tidal Forces". Sixty Symbols. Brady Haran for the University of Nottingham.
- "Pau Amaro Seoane MODEST working group 4 "Tidal disruption of a star by a massive black hole"". Retrieved 2013-05-30.
- Myths about Gravity and Tides by Mikolaj Sawicki of John A. Logan College and the University of Colorado.
- Tidal Misconceptions by Donald E. Simanek | <urn:uuid:76835625-c854-46e7-97d9-36929c649781> | 4.25 | 2,534 | Knowledge Article | Science & Tech. | 54.609672 | 95,483,471 |
February 18 2016 Astronomy Newsletter
Here's the latest article from the Astronomy site at BellaOnline.com.
Gravitational Waves – What Are They?
In February 2016 news of gravitational waves went round the world. But what are these waves sometimes described as ripples in spacetime? To find out let's go back over a century to a time when Albert Einstein was completing the work that would change our view of the Universe.
*A final goodnight to Philae*
Last week ground control made the decision not to send any more commands to the lander Philae, which has been silent since July 2015. The comet is moving farther from the Sun, so not only is there less sunlight to charge the batteries, but Philae's solar panels are likely to have acquired a coating of dust by now. In addition, temperatures drop to -180 degrees Celsius, which is too cold for the lander to function. Although Philae's landing didn't go as it should have, the lander but still completed “about 80% of its initial planned scientific activities,” according to ESA. Rosetta will still listen for communications, even though it's stopped sending new signals. Some background to the mission: http://www.bellaonline.com/articles/art182574.asp
February 15 was the third anniversary of the Chelyabinsk meteorite. Here is the fireball recorded by a dashcam from Kamensk-Uralsky north of Chelyabinsk where it was still dawn: http://www.universetoday.com/wp-content/uploads/2014/02/Chelyabinsk-fireball-dashcam-best-1024x599.jpg. Since light travels faster than sound, the fireball caught people's attention. Some people indoors rushed to the window to see what was happening. The meteor exploded and set off a series of sonic booms that broke windows. Fortunately, no one was killed, but a few thousand needed treatment, mostly injuries related to broken glass.
(1) Galileo Galilei was born on February 15, 1564. He was one of the first to turn the newly-invented telescope on the heavens, and is often considered the father of experimental physics. You can learn more about his life in Dava Sobel's “Galileo's Daughter”, which is reviewed here: http://www.bellaonline.com/articles/art181602.asp
(2) Nicolaus Copernicus was born on February 18, 1473. He was a distinguished citizen of his city and knowledgable in many fields. However he's best known today for his book arguing that the Sun, not the Earth, is at the center of the Solar System. Seventy years after his death the Church banned it for nearly two centuries. You can read about his life and the hunt for his burial place here http://www.bellaonline.com/articles/art40794.asp and about his astronomy here: http://www.bellaonline.com/articles/art5685.asp
*A very special Valentine*
It came with love from Voyager 1 on the way to the stars on Valentine's Day 1990. I know it doesn't look like much, but Voyager took a last look back at the planets of the Solar System, including its home planet. In these segments, we see Venus, Earth, Jupiter, Saturn, Uranus and Neptune. So the middle top image is Earth, christened "the pale blue dot" by Carl Sagan. http://www.universetoday.com/wp-content/uploads/2013/02/pia00453-580x467.jpg
More about Voyager's primary mission: http://www.bellaonline.com/articles/art182154.asp
Please visit http://astronomy.bellaonline.com/Site.asp for even more great content about Astronomy.
I hope to hear from you sometime soon, either in the forum http://forums.bellaonline.com/ubbthreads.php/forums/323/1/Astronomy or in response to this email message. I welcome your feedback!
Do pass this message along to family and friends who might also be interested. Remember it's free and without obligation.
I wish you clear skies.
Mona Evans, Astronomy Editor
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However, scientists from these institutes based in Grenoble (France) have managed to produce a movie. The actors are not celebrities but a protein whose role is to eliminate toxic molecules. They filmed this protein in action by freezing it at several states. They publish their results this week in Science.
Most of the research done on proteins is based on their study in a resting state and their study in movement is extremely limited due to technological limitations. Today, a French team has made a movie of an enzyme (a protein that catalyses chemical reactions) found in bacteria. “The achievement of this research is two-fold: on one side there is the technological success of filming an enzyme in action and on the other hand there are the results that contribute to the knowledge of how this enzyme works”, explains Dominique Bourgeois, corresponding author for the paper.
The enzyme filmed in action is called “superoxide reductase”, its role is to eliminate a toxic molecule called “superoxide radical”. In order to survive, all living organisms have to fight oxidative stress, produced by outflows of the oxygen metabolism. In humans, about 2% of the oxygen used to breathe is transformed into this toxic “superoxide radical” molecule, instead of water. This production is increased in people affected by neurodegenerative diseases such as Alzheimer. A high amount of these molecules worsen these illnesses, so scientists are looking for drugs to eliminate them.
The enzyme studied by the team acts uniquely in bacteria and its counterpart in humans is more complex. Synthesizing an enzyme like the one studied through biomimetics is an exciting possibility for developing future drugs.
In order to produce the film, the team used the ESRF-IBS “Cryobench” laboratory to freeze the protein in three different states while the reaction took place. In order to make sure that they “trapped” the right intermediate states, the researchers used the technique of Raman spectroscopy. This technique provided them with strong evidence that the states were the appropriate ones by showing them the chemical bonds in each stage of the reaction. Once they had identified the right states, they studied the sample with synchrotron x-rays. “We expect this new methodology to be of use for many researchers in the field”, Bourgeois explains.
Filming certain proteins whilst reactions occur has been possible at the ESRF for some years. However, experiments until today were restricted to proteins that get excited by light and are in very resistant crystals.
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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A light earthquake with magnitude 4.3 (ml/mb) was detected on Tuesday, 24 kilometers (15 miles) from Y in Alaska. A tsunami warning has been issued near Y in Alaska (Does not indicate if a tsunami actually did or will exist). The temblor was detected at 18:29:09 / 6:29 pm (local time epicenter). Exact time and date of event in UTC/GMT: 26/04/17 / 2017-04-26 03:29:09 / April 26, 2017 @ 3:29 am. All ids that are associated to the event: at00oozz0l, ak15819827. Unique identifier: ak15819827. Exact location of event, longitude -149.393 West, latitude 62.1906 North, depth = 34.9 km. The earthquake occurred at a depth of 34.9 km (22 miles).
Epicenter of the event was 76 km (47 miles) from Knik-Fairview (c. 14 900 pop), 65 km (40 miles) from Lakes (c. 8 400 pop), 63 km (39 miles) from Tanaina (c. 8 200 pop), 68 km (42 miles) from Wasilla (c. 7 800 pop), 64 km (40 miles) from Meadow Lakes (c. 7 600 pop), 67 km (42 miles) from Palmer (c. 5 900 pop). Nearest cities/city/villages to epicentrum/hypocenter was Knik-Fairview, Gateway, Wasilla (min 5000 pop). Close country/countries that might be effected, United States (c. 310 233 000 pop).
Earthquakes 4.0 to 5.0 are often felt, but only causes minor damage. Each year there are an estimated 13,000 light earthquakes in the world. In the past 24 hours, there have been one, in the last 10 days three, in the past 30 days six and in the last 365 days sixty-nine earthquakes of magnitude 3.0 or greater that have been detected in the same area.
How would you describe the shaking?
How did you respond? Did any furniture slide, topple over, or become displaced? Leave a comment or report about activity, shaking and damage at your home, city and country. This information comes from the USGS Earthquake Notification Service. Read more about the earthquake, Seismometer information, Date-Time, Location, Distances, Parameters and details about this quake, recorded: 24 km E of Y, Alaska.
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New method makes building 'one-handed' drugs easier than ever
Chemists at The Scripps Research Institute (TSRI) have invented a new technique for constructing one-handed or "chiral" drug molecules. The new method is already being adopted by pharmaceutical researchers.
"This new process provides an entirely new pathway for constructing one of the 'cornerstones' of chiral molecules, namely, beta-chiral centers, and should accelerate the development of chiral drugs," said senior author Jin-Quan Yu, Frank and Bertha Hupp Professor in the Department of Chemistry at TSRI.
The new method, published in the September 2, 2016 issue of the journal Science, is a major addition to the molecule-construction toolkit.
A molecule that is chiral is physically not symmetric; it thus has a "mirror image" form that looks different in the way that a right hand looks different from a left hand. Often only one of these two chiral forms has the desired drug properties—the other one may even cause unwanted side effects.
Most modern drugs therefore contain just one chiral form of the drug molecule. Achieving this isn't always easy, though; there are relatively few useful reactions that yield single chiral forms rather than a roughly equal mix of both.
In the new study, the team tackled the problem of adding chiral asymmetry to a common organic structure in which, at one end, a carbon atom is attached to two hydrogen atoms via single bonds—a "beta methylene" in chemists' parlance.
Selectively replacing just one of the two hydrogens with a new cluster of atoms (known as a functional group) would make the structure asymmetric and would enable the construction of beta-chiral centers in a wide variety of chiral drug molecules. However, chemists have not had an easy method for doing this—the standard textbook method, conjugate addition, requires the additional step of creating a double bond at the carbon.
Yu's lab in recent years has helped pioneer a number of new strategies that can direct a palladium atom—whose properties make it an excellent bond-breaking catalyst in many contexts—to a precise location on an organic molecule, in order to rip apart a selected carbon-hydrogen bond. In this case, Yu's team engineered a chiral catalyst that can direct a palladium atom to displace just one or the other hydrogen selectively on a beta methylene carbon atom to create asymmetry. The displacement in this case allows the hydrogen's replacement by a variety of aryl groups—structures that are commonly used in drug molecules.
The catalyst structure includes two palladium-holding clusters of atoms called quinoline and NHAc groups. Such bidentate (literally: double-toothed) compounds normally have what is called a five-membered ring chelating structure, but in this case, a five-membered structure proved too rigid to accommodate the necessary reactions.
"In addition to the exquisite design of the quinoline and NHAc motifs, we ended up engineering a six-membered ring chelating structure, which is more flexible—that was surprising, but very important to our success," said Gang Chen, a research associate in the Yu Laboratory who was first author of the paper.
The new technique works well with two broad and relatively inexpensive classes of starting compounds, aliphatic amides and free carboxylic acids, providing efficient yields and very high ratios of the desired chiral form over the other.
In principle, the technique can be broadened even further. "We are now working to extend this reaction to other starting materials such as alkyl amines and alcohols," Yu said. "We are also working on methods for replacing the carbon-hydrogen bond not just by aryls but by a much wider variety of nitrogen and oxygen-containing organic fragments."
Through an ongoing research collaboration agreement with TSRI, the pharmaceutical company Bristol Myers-Squibb is already using the new method for making a chiral γ-amino acid needed for the synthesis of a candidate drug.
In the fundamental study of how the new catalyst functions, Yu and his team collaborated with the University of California, Los Angeles (UCLA) laboratory of chemist Kendall N. Houk to develop a "stereomodel" of the catalyst and its interactions with the starting material. "This stereomodel should pave the way for further refinement of chiral catalysts," said Yu.
Provided by: The Scripps Research Institute | <urn:uuid:d0af6824-cfef-425d-abff-8390fb45faef> | 3.140625 | 943 | News Article | Science & Tech. | 25.47181 | 95,483,544 |
The Cerrado region in Brazil has been identified as the most biologically diverse savanna on Earth, and Emas National Park is an important protected area for populations of wide-ranging large mammals such as giant anteaters, jaguars and puma.
But at about 500 square miles, the park is too small on its own to protect those species, said Carly Vynne, director of wildlife and habitat for the National Fish and Wildlife Foundation, who studied the effect of land-use changes on mammals in the Cerrado as part of her University of Washington doctoral work.
A major concern is that areas around the park are rapidly being converted to farmland, making the park more like "an island in a sea of agriculture," Vynne said.
A Brazilian law requiring landowners to leave 20 percent of their farms' original vegetation intact could be key in preservation efforts, giving the animals significantly more room to roam outside the park, though there are some efforts to change that.
The effect of the law is to create "an interesting mosaic" combining a well-managed preserve linked to a network of forested river corridors and patches of woodland left intact on adjacent private land, Vynne said.
She led a team that studied how keeping some private land in natural habitat affected preservation efforts in the Cerrado, and the work was published last month in PLoS One, a journal of the Public Library of Science.
"We often hear about the bison trying to leave Yellowstone (National Park), or the grizzlies trying to move out. This was the same kind of situation," she said.
The researchers gathered evidence on the range and habitat favored by five species of large mammals – jaguar, puma, giant anteater, giant armadillo and maned wolf – in 2004 and again from 2006 through 2008. Using a team of dogs from the Center for Conservation Biology's famed troupe of scat-hunting conservation canines, the scientists gathered scat from each species and pieced together profiles of areas the animals tended to inhabit.
They found that the giant armadillos and jaguars favored the protected habitat of the park, possibly because they are more sensitive to disturbances involved with working agricultural land outside the park.
"The jaguars and the giant armadillos need 50 percent natural area for the habitat to be effective," Vynne said. For the other species, "just having habitat available outside the park allows them to use the landscape as a whole."
The finding comes at a time when some are trying to reduce the amount of land property owners in the Cerrado must keep in natural habitat, or to allow them to alter the use of their land near the park in exchange for keeping land elsewhere in its natural state.
"Reducing the land near the park that is left in natural habitat would likely have pretty significant implications," Vynne said.She noted that already some agriculture land is being converted to sugar cane from soy beans, again altering the habitat and potentially changing significantly how the large mammals can use the area.
For more information, contact Vynne at 206-437-5247 or firstname.lastname@example.org
Vince Stricherz | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
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|Neopalpa neonata (left) and Neopalpa donaldtrumpi (right)|
Two, see text
|Distribution of N. neonata (red dots) and N. donaldtrumpi (yellow triangles)|
Neopalpa is a genus of moths in the family Gelechiidae. They are found in California, Arizona, and northern Mexico. Neopalpa is classified in the tribe Gnorimoschemini and is most closely related to the genera Ochrodia and Ephysteris.
The genus contains the following two species:
|Wikispecies has information related to Neopalpa|
- Nazari, Vazrick (2017). "Review of Neopalpa Povolný, 1998 with description of a new species from California and Baja California, Mexico (Lepidoptera, Gelechiidae)". ZooKeys. 646: 79–94. doi:10.3897/zookeys.646.11411.
- "Neopalpa Povolný, 1998" at Markku Savela's Lepidoptera and Some Other Life Forms
|This article on a moth of the Gelechiinae subfamily is a stub. You can help Wikipedia by expanding it.| | <urn:uuid:432f28db-cc05-479d-980c-f29b5cb67a2a> | 2.78125 | 271 | Knowledge Article | Science & Tech. | 41.66 | 95,483,603 |
What is Waterspout?
Waterspout meaning In general, a tornado occurring over water. Specifically, it normally refers to a small, relatively weak rotating column of air over water beneath a Cb or towering cumulus cloud. Waterspouts are most common over tropical or subtropical waters.
The exact definition of waterspout is debatable. In most cases the term is reserved for small vortices over water that are not associated with storm-scale rotation (i.e., they are the water-based equivalent of landspouts). But there is sufficient justification for calling virtually any rotating column of air a waterspout if it is in contact with a water surface.
reference: National Weather Service Glossary | <urn:uuid:1f2f6bcc-5502-4769-af37-3490c7ba3cd6> | 3.453125 | 149 | Knowledge Article | Science & Tech. | 29.222956 | 95,483,617 |
Filters: Tags: river banks (X)72 results (9ms)
Bank erosion management based on geomorphological, ecological and economic criteria on the Galaure River, France
Downstream effects of dams on channel geometry and bottomland vegetation: Regional patterns in the great plains
Vegetation and chemism of running waters in the upper part the Otava catchment as indicators of anthropogenic impact
Ecosystem Linkages between Southern Appalachian Headwater Streams and Their Banks: Leaf Litter Breakdown and Invertebrate Assemblages
Substrate-specific distribution of Ephemeroptera, Plecoptera and Trichoptera (Insecta) in a sandy stream of the north German lowland (Osterau, Schleswig-Holstein).
Habitat features important for the conservation of the native crayfish Austropotamobius pallipes in Britain
Protection and development of the Seine river banks; reflection on the integration of the river in an urban environment
Grasshoppers (Orthoptera, Saltatoria) on alpine and dealpine riverbanks and their use as indicators for natural floodplain dynamics. | <urn:uuid:c4f3b445-bf60-4e57-bd85-b452b737ed21> | 2.578125 | 242 | Content Listing | Science & Tech. | -46.6075 | 95,483,641 |
Ecological engineering is an emerging study of integrating ecology and engineering, concerned with the design, monitoring and construction of ecosystems. The design of sustainable ecosystems intends to integrate human society with its natural environment for the benefit of both . This particular type of engineering emerged in the early 1960s. It utilized natural energy sources as the predominant input to manipulate and control environmental systems.
Mitsch and Jorgensen were the first to define ecological engineering in five concepts :
- It is based on the self-designing capacity of ecosystems
- It can be a field test of ecological theory
- It relies on integrated system approaches
- It conserves non-renewable energy
- It supports biological conservation
Ecological engineering design follow a similar cycle to engineering design problem formulation, problem analysis, alternative solutions search, decision among alternatives and specifications of a complete solution. Typically the design goal involves protecting an at-risk ecosystem, restoring a degraded ecosystem or creating a new sustainable ecosystem to satisfy need of nature and society.
W.J. Mitsch & S.E. Jorgensen (1989), "Introduction to Ecological Engineering", In: W.J. Mitsch and S.E. Jorgensen (Editors), Ecological Engineering: An Introduction to Ecotechnology. John Wiley & Sons, New York, pp. 3-12.© BrainMass Inc. brainmass.com July 21, 2018, 7:27 pm ad1c9bdddf | <urn:uuid:52f832a1-60a2-4f73-92f9-7c8ab4f8b6f8> | 3.125 | 296 | Knowledge Article | Science & Tech. | 19.183876 | 95,483,648 |
Sustainability may not be all it’s cracked up to be. That is the message in a recent paper by a hydrogeologist at Reading University . Michael Price argues that most human advances have been non-sustainable in the long term and that when we talk of ‘sustainable use’ we must define the period over which the use is planned or implemented.
Price identifies three major challenges currently facing Britain and the world. The first is that the climate, and with it the supply of water, is becoming less predictable. Since 1975 Great Britain has suffered four droughts, each of which has been estimated to have a return period of more than 200 years. In 2000-1, parts of England experienced some of the worst instances of flooding on record. Global climate models predict that we can expect more droughts and more periods of heavy rainfall accompanied by increased occurrences of flooding.
The second challenge is that the global demand for fresh water will increase, as population increases and the standard of living improves. It has been argued that in Britain we can counter this increased demand by metering water and making it more expensive. However, consumption of water per head of population in Britain is below that of many other developed countries where domestic water is metered. The stark truth is that demand for water is almost directly related to prosperity - as disposable income increases, water use increases.
Sue Rayner | alphagalileo
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
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When was the first instrument that actually recorded an earthquake?
The earliest seismoscope was invented by the Chinese philosopher Chang Heng in A.D. 132. This was a large urn on the outside of which were eight dragon heads facing the eight principal directions of the compass. Below each dragon head was a toad with its mouth opened toward the dragon. When an earthquake occurred, one or more of the eight dragon-mouths would release a ball into the open mouth of the toad sitting below. The direction of the shaking determined which of the dragons released its ball. The instrument is reported to have detected an earthquake 400 miles away that was not felt at the location of the seismoscope. The inside of the seismoscope is unknown: most speculations assume that the motion of some kind of pendulum would activate the dragons.
Learn more: The Early History of Seismometry (to 1900)
The USGS Earthquake Hazards Program recently released a new strategic plan for earthquake monitoring entitled the “Advanced National Seismic System – Current Status, Development Opportunities, Priorities, 2017-2027.”
The Hawaiian Volcano Observatory’s 1912–2012 Centennial—100 Years of Tracking Eruptions and Earthquakes
HAWAI‘I ISLAND, Hawaii —The history of earthquakes and seismic monitoring in Hawai‘i during the past century will be the topic of a presentation at the University of Hawai‘i at Hilo on Thursday, January 26, at 7:00 p.m.
USGS will Grant Universities $5 Million to Beef Up Public Safety Grants totaling $5 million under the American Recovery and Reinvestment Act are being awarded to 13 universities nationwide to upgrade critical earthquake monitoring networks and increase public safety.
Guided by Japanese writings from an era of shoguns, an international team of scientists today reported new evidence that an earthquake of magnitude 9 struck the northwestern United States and southwestern Canada three centuries ago. The findings are likely to affect the region’s precautions against future earthquakes and tsunamis.
On January 26, 1700, the largest earthquake known to have occurred in the "lower 48" United States, rocked Cascadia, a region 600 miles long that includes northern California, Oregon, Washington, and southern British Columbia.
Block diagram illustrating an idealized geological setting offshore the state of Washington. As the subducting Juan De Fuca tectonic plate dives beneath North America, it can generate an earthquake, and trigger a tsunami.
Seismometers (instruments for recording earthquakes) are tested and fitted at the USGS Cascades Volcano Observatory before going out into the field.
A seismometer deployed near the epicenter of the Greeley earthquake in 2014.
Map of ANSS free-field seismic stations across the U.S. in 2016 (not shown are additional seismic instruments in buildings and other structures). Map colors show seismic hazard across the United States derived from the National Seismic Hazard Model. Background colors indicate the levels of shaking that have a 2% chance of being exceed in a 50-year period. Shaking is expressed in a percentage of g, which is the acceleration of a falling object due to gravity, with red colors indicating highest shaking and thus higher hazard. Notice the greater density of stations in regions with either higher hazard, higher risk (e.g., southern California), or both.
Traditional seismic stations such as this one require a source of power (solar here), a poured concrete foundation and several square feet of space. They are not always practical to install in urban areas, and that's where NetQuakes comes in. | <urn:uuid:0d836e04-c8c3-4260-aa22-f2841aad357d> | 3.90625 | 740 | Knowledge Article | Science & Tech. | 38.376545 | 95,483,666 |
Intelligence, compassion, consciousness. These are some of the most fundamental aspects of what it means to be human. Yet, biologists struggle to settle on common definitions for these complex traits, let alone explain how they arise from the electrical signals fired by the million of neurons that make up our brain.
Major American and European initiatives are pouring hundreds of millions of dollars into mapping and modeling the electrical circuitry of the human brain. But not everyone in the neuroscience community thinks these projects are on the right track.
"The BRAIN Initiative supports attempts to develop new methods that will add to our knowledge," explains John Lisman, Zalman Abraham Kekst Chair in Neuroscience and Professor of Biology at Brandeis University, "The particular feeling we have is that even more rapid progress can be made largely on existing knowledge."
Paul Verschure, head of the Synthetic, Perceptive, Emotive and Cognitive Systems research group at Universitat Pompeu Fabra, agrees, saying that what brain science needs at this point is not more data, but more ideas, and more experiments to test those ideas.
Just what would such an approach look like? For one, Lisman says, biologists who have traditionally studied one little part of the brain in minute detail need to step back and think about how that piece functions as part of the whole. And then, say both Lisman and Verschure, they need to test those ideas. And that's where robots come in.
But it requires a different attitude toward robotics than is currently the norm. To date, many robots have been built to perform a specific task - pick up an object, walk, play chess - using any means to accomplish that end. Vershure and Tony Prescott, Professor of Cognitive Neuroscience at the University of Sheffield and Director of the Sheffield Centre for Robotics, advocate building robots based on our best understanding of how the human nervous system works, and then seeing whether such robots behave in expected ways. Basically, robots become experiments to test biological hypotheses.
That's significantly harder than it might sound because, as Prescott points out, our brains are not disembodied computers. Our brains are constantly taking in information from all of our senses, and then sending signals back out to our bodies. To accurately test theories about how the brain works, robots need bodies and senses, as well.
If the idea of intelligent, embodied robots evokes post-apocalyptic images of humanity enslaved by our own creations, relax (or don't). Verschure and Prescott say we've already happily made ourselves slaves to much less sophisticated technologies. But they are both hopeful that a human-centered approach to robotics can not only help us understand ourselves more deeply, but also produce technologies that improve the human condition and actually enhance - rather than detract from - our humanity. | <urn:uuid:18314958-7bf0-46be-aabe-aba49cdf6de6> | 3.75 | 566 | News Article | Science & Tech. | 32.816652 | 95,483,690 |
A thioether is a functional group in organosulfur chemistry with the connectivity C–S–C as shown on right. Like many other sulfur-containing compounds, volatile thioethers have foul odors. A thioether is similar to an ether except that it contains a sulfur atom in place of the oxygen. The grouping of oxygen and sulfur in the periodic table suggests that the chemical properties of ethers and thioethers are somewhat similar, though the extent to which this is true in practice varies depending on the application.
Thioethers are sometimes called sulfides, especially in the older literature and this term remains in use for the names of specific thioethers. The two organic substituents are indicated by the prefixes. (CH3)2S is called dimethylsulfide. Some thioethers are named by modifying the common name for the corresponding ether. For example, C6H5SCH3 is methyl phenyl sulfide, but is more commonly called thioanisole, since its structure is related to that for anisole, C6H5OCH3.
Structure and properties
Thioether is an angular functional group, the C–S–C angle approaching 90°. The C–S bonds are about 180 pm.
Thioethers are characterized by their strong odors, which are similar to thiol odor. This odor limits the applications of volatile thioethers. In terms of their physical properties they resemble ethers but are less volatile, higher melting, and less hydrophilic. These properties follow from the polarizability of the divalent sulfur center, which is greater than that for oxygen in ethers.
Thiophenes are a special class of thioether-containing heterocyclic compounds. Because of their aromatic character, they are non-nucleophilic. The nonbonding electrons on sulfur are delocalized into the π-system. As a consequence, thiophene exhibits few properties expected for a thioether – thiophene is non-nucleophilic at sulfur and, in fact, is sweet-smelling. Upon hydrogenation, thiophene gives tetrahydrothiophene, C4H8S, which indeed does behave as a typical thioether.
Occurrence and applications
Thioethers are important in biology, notably in the amino acid methionine and the cofactor biotin.Petroleum contains many organosulfur compounds, including thioethers. Polyphenylene sulfide is a useful high temperature plastic. Coenzyme M, CH
3, is the precursor to methane (i.e. natural gas) via the process of methanogenesis.
- R–Br + HS–R′ → R–S–R′ + HBr
Such reactions are usually conducted in the presence of base, which converts the thiol into the more nucleophilic thiolate. Analogously, the reaction of disulfides with organolithium reagents produces thioethers:
- R3CLi + R1S–SR2 → R3CSR1 + R2SLi
Analogous reactions are known starting with Grignard reagents.
Alternatively, thioethers can be synthesized by the addition of a thiol to an alkene:
- R–CH=CH2 + HS–R′ → R–CH2–CH2–S–R′
This reaction is often catalysed by free radicals.
Thioethers can also be prepared by many other methods, such as the Pummerer rearrangement. Trialkysulfonium salts react with nucleophiles with a dialkyl sulfide as a leaving group:
- Nu− + R3S+ → Nu–R + R–S–R
While, in general, ethers are non-oxidizable, thioethers can be easily oxidized to the sulfoxides (R–S(=O)–R), which can themselves be further oxidized to sulfones (R–S(=O)2–R). Hydrogen peroxide is a typical oxidant. For example, dimethyl sulfide can be oxidized as follows:
- S(CH3)2 + CH3I → [S(CH3)3]+I−
Binding to transition metals
In analogy to their easy alkylation, thioethers bind to metals to form coordination complexes. They are classified as soft ligands, but their affinity for metals is lower than typical phosphines. Chelating thioethers are known, such as 1,4,7-trithiacyclononane.
Thioethers undergo hydrogenolysis in the presence of certain metals:
- R–S–R′ + 2 H2 → RH + R′H + H2S | <urn:uuid:389a3efe-e063-4dd7-930b-324beb772dd1> | 3.265625 | 1,022 | Knowledge Article | Science & Tech. | 40.330851 | 95,483,701 |
“We commend the Government of Argentina for their conservation stewardship in creating this new network of marine protected areas,” said Dr. Cristián Samper, President and CEO of the Wildlife Conservation Society. “Isla Pingüino and Makenke Coastal Marine Parks now protect vital wildlife populations for posterity and create new opportunities for Argentina’s ecotourism industry.”
Stretching some 80 miles south of Puerto Deseado and extending 12 miles out to sea, Isla Pingüino covers nearly 1,800 square kilometers (720 square miles) of ocean and cliff-bordered coastline. The new protected area contains large populations of South American sea lions, red-legged cormorants, and one of the largest colonies of imperial cormorants found anywhere (with more than 8,000 breeding pairs). Isla Pingüino also boasts one of the only colonies of rockhopper penguins on the coast of Patagonia.
Farther south, the Makenke Coastal Marine Park begins at the entrance of the Ría San Julián, covering almost 600 square kilometers (230 square miles) of shore and ocean. The park contains the largest colony of rare red-legged cormorants in the country. It also protects breeding colonies of the dolphin gull, a rare scavenger, and pods of the small but spectacular black and white Commerson’s dolphin
Both marine protected areas are steeped in history as well as natural wonders. Charles Darwin traveled to the region now contained in Isla Pingüino in 1833, describing the wildlife he observed there during his seminal voyage aboard the HMS Beagle. Makenke Coastal Marine Park now borders the inlet of San Julian, where in 1520 Ferdinand Magellan executed and marooned a group of mutineers intent on aborting what would become the world’s first circumnavigation of the globe.
“We commend the National Congress in Argentina for passing laws to create these new marine parks, which will protect the country’s natural heritage given what will likely be an increase in development along the coast in years to come,” said Dr. Julie Kunen, Director for WCS’s Latin America and Caribbean Program.
Dr. Caleb McClennen, Director of WCS’s Marine Program, said: “Isla Pingüino and Makenke Coastal Marine Parks continue a tradition of conservation teamwork, with organizations such as WCS providing support to the government in protecting both coastal breeding areas for mammals and birds and the marine habitats they rely upon.”
Isla Pingüino and Makenke Coastal Marine Parks were made possible as a result of work conducted by Dr. Patricia Gandini, President of the National Parks Service, and Dr. Esteban Frere of the Universidad Nacional de la Patagonia Austral. Both biologists began studying the wildlife of the coast of Santa Cruz with support of WCS in 1985.
Both areas were identified as priority conservation sites by the Patagonia Coastal Zone Management Plan project, carried out by both the Wildlife Conservation Society and the Fundación Patagonia Natural with support from the Global Environmental Facility and the UNDP (United Nations Development Program). Support for the research was also provided by the Consejo Nacional de Investigaciones Científicas y Técnicas (Conicet).
WCS has been involved in the conservation of coastal Patagonia since the 1970s, beginning with Dr. Roger Payne’s behavioral work on southern right whales, and continues to this day with research by WCS’s Global Health Program on new threats to their survival. WCS began a long-running study on Magellanic penguins in the 1980s. That work led to conservation efforts that helped reduce the number of penguin deaths due to oil spills at sea from more than 40,000 a year to fewer than 1,000 annually, and helped move shipping lanes 30 miles offshore to avoid spills affecting seabird colonies.
WCS has also been conducting research on southern elephant seals, South American sea lions, rockhopper penguins, cormorants, gulls, terns, and other species that breed along the shores of Patagonia. These studies informed the region’s first atlas of breeding seabirds, a work designed to guide management decisions on fisheries and other natural resource usage. Over the past 40 years WCS has helped Argentina transition from harvesting of coastal wildlife to a burgeoning tourism industry based on its spectacular coastal species. These two new parks are the latest addition to the country’s extraordinary marine conservation effort.
WCS's efforts to help protect wildlife on the Argentine coast and sea are generously supported by the Liz Claiborne and Art Ortenberg Foundation, the Mitsubishi Corporation Foundation for the Americas, the Waitt Foundation, and others.
The Wildlife Conservation Society saves wildlife and wild places worldwide. We do so through science, global conservation, education and the management of the world's largest system of urban wildlife parks, led by the flagship Bronx Zoo. Together these activities change attitudes towards nature and help people imagine wildlife and humans living in harmony. WCS is committed to this mission because it is essential to the integrity of life on Earth. Visit www.wcs.org.
The Mitsubishi Corporation Foundation for the Americas, based in New York City was established 1991 with funding from Mitsubishi Corporation of Japan, and its U.S.-based subsidiary, Mitsubishi International Corporation. Since its establishment, the Foundation has dedicated more than $7.2 million to environmental causes throughout the Americas. For more information, please visit http://www.mcfamericas.org.
Funding partnerships and projects in conjunction with its grantees and institute, the Waitt Foundation supports a variety of national and international programs concentrating on ocean conservation initiatives and marine related issues. By increasing global awareness, our goal is to reverse the current decline of ocean life while inspiring humanity to make informed choices that contribute to a healthy marine ecosystem.
Special Note to the Media: If you would like to guide your readers or viewers to a Web link where they can make donations in support of helping save wildlife and wild places, please direct them to wcs.org.
Stephen Sautner | Newswise
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Edited By: Hans-Dieter Sues
256 pages, 55 line diagrams 25 half-tones 6 tables
Although herbivory probably first appeared over 300 million years ago, it only became established as a common feeding strategy during Late Permian times. Subsequently, herbivory evolved in numerous lineages of terrestrial vertebrates, and the acquisition of this mode of feeding was frequently associated with considerable evolutionary diversification in those lineages. This book represents the first comprehensive overview of the evolution of herbivory in land-dwelling amniote tetrapods in recent years. In Evolution of Herbivory in Terrestrial Vertebrates leading experts review the structural adaptations for, and the evolutionary history of, feeding on plants in the major groups of land-dwelling vertebrates, especially dinosaurs and ungulate mammals. As such it will be the definitive reference source on this topic for evolutionary biologists and vertebrate paleontologists alike.
'The chapters are elegant, well presented and well illustrated, and the authors, the editor and the publishers are to be congratulated.' Michael J. Benton, Trends in Ecology and Evolution '! nicely produced, and yields many provocative papers that are of interest to anyone who has thought about terrestrial paleoecology.' Donald R. Prothero, PRISCUM
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Cosmic rays are constantly entering the Earth's atmosphere, many from outside our Solar System, although (but not always) with a minimal effect. Some of these rays move with much greater energy than others (ultra-high energy cosmic rays, or UHECR, with an energy of more than 10^18 eV), and are still a mystery to researchers.
Researchers from the Laboratory of Methods for Big Data Analysis (LAMBDA) at the Higher School of Economics in Russia have proposed a way of analysing these rays using mobile phones.
UHECR form cascades of secondary particles (extended atmosphere showers, EAS) on entering our atmosphere. They are rare, though; a 1km² detector would detect such an event about once in 100 years.
To improve detection rates, scientists have proposed using a distributed network of mobile phones to detect UHECR. The work would involve an algorithm, developed by the researchers at LAMBDA, to build convolutional neural networks that could record the particles (muons) that form the EAS using mobile phone cameras.
CMOS sensors used in smartphone cameras are similar to those that exist in particle detectors. Muon particles interact with the sensors and leave traces of weakly-activated pixels, although these can be difficult to separate from normal interference. This is where the neural network comes in.
Andrei Ustyuzhanin, head of LAMBDA at HSE, said: "A trigger algorithm is required to eliminate background data. We created a neural network for for the detection of muon signals, which can be used on any mobile phone fast enough to process a video stream. A special feature makes it possible to use the algorithm on something as simple as a mobile phone, meaning that they can now analyse responses to cosmic rays."
Volunteers can install a custom application onto their smartphone and leave them overnight, with the camera facing downwards to hide it from normal light. The phone scans images at a rate of between five and 15 frames per second, sending this information to the server. Detection of UHECR is expected to occur in less than one in 500 such images.
Microsoft receives a 30 per cent cut of all purchases on the Xbox digital store
Credit card thieves used Apple ID accounts to buy and sell virtual currency for Clash of Clans and Clash Royale and Marvel Contest of Champions
$5.1bn fine further evidence that the EU is anti-US, claims Trump
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Sediments accumulate on deep ocean floors at a rate of a few centimetres every thousand years. The study of this – called stratigraphy – involves drilling vertically down into the sea bed to extract a sample core which gives a picture of continually changing life, environment and climate.
Dr. Jan Zalasiewicz, of the University of Leicester’s Department of Geology, together with Professor Paul Pearson of Cardiff University and colleagues at the Stratigraphy Commission of the Geological Society of London, propose that exhibiting a core will dramatically illustrate how brief human history has been. A continuous core going back 64 million years – to the time of the dinosaurs - would be 1.5km long.
Writing in the journal ‘Geoscientist’, he said: “On this scale, the last 10,000 years in which civilization developed is about 30cm thick… and the time since the Industrial Revolution is represented by just a few millimetres of sediment.”
Key events could be marked, such as the evolution of humans and also, more importantly, the huge lengths of time over which the Earth has endured, and recovered from previous climactic upheavals such as ice ages.
He continues: “At the base of the core a signpost would point to the formation of the Earth, 100km away, and the origin of the universe at 300km.”
The exhibition, if ever realised, would be comparable in scale to the UK’s National Space Centre, the brainchild of the University of Leicester, or the Eden Project.
Ather Mirza | alfa
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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You may ask yourself, what is all this about the different types of sites?, I hear all these different things as static web page or dynamic web site, or even e-commerce web sites. If you are interested in knowing what are the differences, then continue reading. This page will seek to explain the way in which static web sites are built and noted some of its benefits, as well as some disadvantages that go along with a site that is static in nature. Static site construction what is what designers mean when they say that a web design is static?. Well, since it is not possible to speak for all designers, is here looking for help you get the main idea that explains how to use the term. To read more click here: Declan Kelly. Web sites can be constructed in a very large variety of forms.
One way is to use a language known as HTML (HyperText Markup Language). This language is relatively easy to learn and use for basic web pages. Therefore, many, many people are able to use this method of writing a web page. Do it yourself often take an intensive course in HTML and in a week, or even a couple of days, you may be able to make a website running on the internet. The HTML pages are static in the sense that the code in your HTML page is sent to the web browser (Internet Explorer, Firefox, etc.) and this is who is responsible for displaying it. The HTML appears in the browser exactly the way in which was written by the programmer. After the browser receives the file from the hosting server, reads the code and the page is displayed. There are no decisions made by the server or the browser.
The abstract serve a static page is something like: the request made by the visitor of the website server locates the requested file server sends the requested file (s) back to the browser the browser reads the HTML code and displays the design of web page basically, who wrote the programmer, is sent to the browser of the spectator. This method is what many designers mean when they use the word static pages. As with most things, there are pros and cons. It hires the best Plan of Web Hosting called without cost 01 800 632 1001 original author and source of the article | <urn:uuid:53ab27c7-6136-4309-9cd4-e8c1609d5702> | 2.828125 | 457 | Truncated | Software Dev. | 58.104868 | 95,483,765 |
A golf ball (m = 46.0 g) is struck with a force that makes an angle of 45.7° with the horizontal. The ball lands 207 m away on a flat fairway. If the golf club and ball are in contact for 7.06 ms, what is the average force of impact? (Neglect air resistance.)© BrainMass Inc. brainmass.com July 16, 2018, 1:04 am ad1c9bdddf
With equations, calculations and a graph, the problem is solved. | <urn:uuid:ac3a00ea-a4e9-44dc-a1ee-1167b4285c9e> | 3.0625 | 109 | Truncated | Science & Tech. | 98.936789 | 95,483,770 |
THE pesky 1930’s pops up again (hidden in plain sight from the correction-pen of Gavin and NASA-GISS!)
HOW inconvenient that Greenland temps in the 1930’s were as ‘warm’ as today, before CO2 became an issue.
AMO, not carbon dioxide levels, quite clearly controlling temperature ebb and flow in Greenland…
By Paul Homewood
As we all know, Greenland is warming up rapidly, causing the ice sheet to melt faster and faster.
Well, according to the BBC and New York Times, at least.
Only one slight problem – the temperature record shows quite a different story.
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BEFORE NASA climate was completely captured by the radical environmental movement and grant-gleefully sold their soul to the widely debunked “97% of scientists believe that CO2 is the climate control knob” groupthink-consensus-virus, they knew perfectly well that the sun controlled Earth’s climate.
AND, before the new-NASA-activists rewrote climate ‘science’, the National Aeronautics Space Agency boldly (and correctly) noted that “Other important forcings of Earth’s climate system” such as “clouds, airborne particulate matter, and surface brightness [have] the capacity to exceed the warming influence of greenhouse gases and cause our world to cool.”
FROM the above NASA article that disappeared around 2010 :
WHAT ARE THE PRIMARY FORCINGS OF THE EARTH SYSTEM?
The Sun is the primary forcing of Earth’s climate system. Sunlight warms our world. Sunlight drives atmospheric and oceanic circulation patterns. Sunlight powers the process of photosynthesis that plants need to grow. Sunlight causes convection which carries warmth and water vapor up into the sky where clouds form and bring rain. In short, the Sun drives almost every aspect of our world’s climate system and makes possible life as we know it.
Earth’s orbit around and orientation toward the Sun change over spans of many thousands of years. In turn, these changing “orbital mechanics” force climate to change because they change where and how much sunlight reaches Earth. Thus, changing Earth’s exposure to sunlight forces climate to change. According to scientists’ models of Earth’s orbit and orientation toward the Sun indicate that our world should be just beginning to enter a new period of cooling — perhaps the next ice age.
However, a new force for change has arisen: humans. After the industrial revolution, humans introduced increasing amounts of greenhouse gases into the atmosphere, and changed the surface of the landscape to an extent great enough to influence climate on local and global scales. By driving up carbon dioxide levels in the atmosphere (by about 30 percent), humans have increased its capacity to trap warmth near the surface.
Other important forcings of Earth’s climate system include such “variables” as clouds, airborne particulate matter, and surface brightness. Each of these varying features of Earth’s environment has the capacity to exceed the warming influence of greenhouse gases and cause our world to cool. For example, increased cloudiness would give more shade to the surface while reflecting more sunlight back to space. Increased airborne particles (or “aerosols”) would scatter and reflect more sunlight back to space, thereby cooling the surface. Major volcanic eruptions (such as that of Mt. Pinatubo in 1992) can inject so much aerosol into the atmosphere that, as it spreads around the globe, it reduces sunlight and cause Earth to cool. Likewise, increasing the surface area of highly reflective surface types, such as ice sheets, reflects greater amounts of sunlight back to space and causes Earth to cool.
Scientists are using NASA satellites to monitor all of the aforementioned forcings of Earth’s climate system to better understand how they are changing over time, and how any changes in them affect climate.
“HE who controls the past controls the future. He who controls the present controls the past.” – George Orwell
“CLIMATE alarmism is a gigantic fraud: it only survives by suppressing dissent and by spending tens of billions of dollars of public money every year on pseudo-scientific propaganda.” – Leo Goldstein
CLIMATISM TOP 10 ALARMIST MYTHS – Intro
EXCESSIVE or exaggerated alarm about a real or imagined threat is fundamental in driving the human CO2-induced
global warming climate change narrative.
THE most popular climatic and weather-related events, as marketed by the Climate Crisis Industry, fall well within the bounds of natural variability. So, in order for such events to make the headlines, attract taxpayer funding for ‘research’, and advance the misanthropic, man-made climate change agenda, they must be accompanied by inflated language, an urgent tone, imagery of doom, and in many cases, fraudulent data.
IN this series we take an objective/sceptical look at ten of the more popular metrics used by warming alarmists to push the CAGW (catastrophic anthropogenic global warming) narrative, testing the veracity of the all-too-often wild and alarmist claims associated with each…
#3. OCEAN ACIDIFICATION
“Corals evolved during the Cambrian Era six hundred million years ago, with CO2 levels 4000% of what they are now. They are made of Calcium Carbonate (CaCO3) – and could not exist without substantial amounts of CO2 in the atmosphere. Unless the chemical properties of CaCO3 have changed, the corals [and crustaceans] will be just fine.” – Tony Heller
WITH a stubborn atmosphere failing to warm as predicted, another climate threat was needed to sustain the Climate Crisis industry and keep lazy reporters supplied with junk science to feed their catastrophic climate narrative.
ENTER “Ocean Acidification”!
SOUNDS scary right? From the onset, the term “ocean acidification” was deceptive by design. And the only valid ‘science’ in the pseudoscientific study of “Ocean Acidification” is the ‘science’ of scare-mongering.
OCEANS are alkaline. The correct scientific term for any pH change toward zero is “less alkaline”. Obviously not the scariest of descriptors to shock the public into belief.
“OCEAN ACIDIFICATION” was first referenced in a peer-reviewed study in Nature in 2003, resulting in an explosion of journal articles, media reports and alarmist publications from environmental orgs. It has since gone viral, endorsed by scientists from numerous alarmist institutions including the Royal Society, the IPCC and NOAA who coined it “climate change’s evil twin” in a 2016 report.
A 2016 paper published in the ICES Journal of Marine Science put the issue of “ocean acidification” under the microscope, and found Scientists exaggerating the carbon dioxide threat to marine life…
Applying organized scepticism to ocean acidification research
“Ocean acidification” (OA), a change in seawater chemistry driven by increased uptake of atmospheric CO2 by the oceans, has probably been the most-studied single topic in marine science in recent times. The majority of the literature on OA report negative effects of CO2 on organisms and conclude that OA will be detrimental to marine ecosystems. As is true across all of science, studies that report no effect of OA are typically more difficult to publish.
Excerpts from the paper:
Scientific or academic scepticism calls for critical scrutiny of research outputs before they are accepted as new knowledge (Merton, 1973). Duarte et al. (2014) stated that “…there is a perception that scientific skepticism has been abandoned or relaxed in many areas…” of marine science. They argue that OA is one such area, and conclude that there is, at best, weak evidence to support an OA-driven decline of calcifiers. Below, I raise some of the aspects of OA research to which I contend an insufficient level of organized scepticism has been applied (in some cases, also to the articles in this theme issue). I arrived at that conclusion after reading hundreds of articles on OA (including, to be fair, some that also raise these issues) and overseeing the peer-review process for the very large number of submissions to this themed issue. Importantly, and as Duarte et al. (2014) make clear, a retrospective application of scientific scepticism such as the one that follows could—and should—be applied to any piece of/body of research.
FROM an article in The Times :
An “inherent bias” in scientific journals in favour of more calamitous predictions has excluded research showing that marine creatures are not damaged by ocean acidification, which is caused by the sea absorbing carbon dioxide from the atmosphere.
It has been dubbed the “evil twin of climate change” and hundreds of studies have claimed to show that it destroys coral reefs and other marine life by making it harder for them to develop shells or skeletons.
The review found that many studies had used flawed methods, subjecting marine creatures to sudden increases in carbon dioxide that would never be experienced in real life.
Dr Browman, who is also principal research scientist at the Norwegian Institute of Marine Research, found there had been huge increase in articles on ocean acidification in recent years, rising from five in 2005 to 600 last year.
He said that a handful of influential scientific journals and lobbying by international organisations had turned ocean acidification into a major issue.
“Such journals tend to publish doom and gloom stories . . . stated without equivocation,” he said. The bias in favour of doom-laden articles was partly the result of pressure on scientists to produce eye-catching work, he added.
“You won’t get a job unless you publish an article that is viewed as of significant importance to society. People often forget that scientists are people and have the same pressures on them and the same kind of human foibles. Some are driven by different things. They want to be prominent.”
Patrick Moore: Ocean ‘Acidification’ Alarmsim in Perspective
From Moore’s report: Read the rest of this entry »
ESSENTIAL reading and research for the ‘failing’ Guardian and New York Times respectively, who both launched new attack pieces on essential trace gas CO2, claiming this time that “Climate change [CO2] will make rice less nutritious”… 🤔
Before it was expropriated by the global warming/climate change movement, the term “Greenhouse Effect” referred to the effect of elevated carbon dioxide in greenhouses on crop chemistry. We know from greenhouse studies going back to the late 19th century that crop chemistry reflects the balance between soil chemistry, air chemistry, and light intensity. The important features of air chemistry are the availability of carbon dioxide for photosynthesis and of oxygen for plant respiration. The important features of soil chemistry are the availability of water, nitrates, phosphates, and minerals.
Greenhouse operations irrigation, air circulation to maintain air quality, heating for temperature control, the introduction of carbon dioxide to maintain elevated carbon dioxide levels of 1000 to 2000 parts per million for photosynthesis enrichment, and the availability of sufficient light for photosynthesis to occur. Photosynthesis enrichment improves crop yield and corresponding changes to soil chemistry must also be maintained to preserve the…
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AUSTRALIA’S climate when CO2 was at “safe levels”…
The “Federation Drought”, 1895-1902
Many of Australia’s worst droughts occur when one or two very dry years follow several years of generally below average rainfall. Such was the case in the so-called “Federation drought”, which began in the mid 1890s and reached its devastating climax in late 1901 and 1902.
The five years leading up to Federation (January 1901) saw intermittent dry spells over most of the country, particularly in 1897 and 1899; in most of Queensland, dry conditions were virtually unbroken from 1897. Most other parts of the country had reasonable rain in 1900 and early 1901, but with the coming of spring 1901 very dry weather set in across eastern Australia. By February 1902 concerns were expressed about Sydney’s water supply, and the New South Wales Government declared 26 February a day of “humiliation and prayer” for rain in that state. Similar declarations were made in Queensland in…
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+44 1803 865913
By: Peter Francis and Clive Oppenheimer
521 pages, 570 figs
The authors examine the familiar violent aspects of volcanoes and the various forms that eruptions can take. They also explore why volcanoes occur where they do, and how examples of major historical eruptions can be interpreted in terms of physical processes. They attempt to place volcanism in a planetary perspective, exploring the pre-eminent role of submarine volcanism on Earth and the stunning range of volcanic phenomena revealed by spacecraft exploration of the Solar System. The new edition reflects new research findings and new eruptions.
1. The Basics: isotopes and green cheese; 2. Keeping planets cool: volcanoes, hot-spots, and plate tectonics; 3. Four classic eruptions; 4. Magma - the hot stuff; 5. Types of volcanic activity; 6. Lava Flows; 7. Pyroclastic eruptions: bubbles, bangs, columns, and currents; 8. What goes up must come down: pyroclastic fall deposits; 9. Pyroclastic currents from collapsing domes and transient eruptions; 10. Pyroclastic currents and ignimbrites associated with plinian eruptions; 11. Super-eruptions, super-volcanoes and calderas; 12. Debris avalanches and flows: magic carpets and muck; 13. Volcanoes as landscape forms; 14. Submarine volcanism; 15. Extraterrestrial volcanoes; 16. Eruptions and climate; 17. Volcano monitoring; 18. Reducing volcanic risks
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Lack of essential observations from space is currently a major limiting factor in many areas of geospace andatmospheric research.
Recent advances in sensor and spacecraft technologies make it feasible to obtain key measurements from low-cost, small satellite missions.
credit: Wikimedia Commons via Flickr
promising aspect of this development is the prospect for obtaining multi-point observations in space that are critical for addressing many outstanding problems in space and atmosphericsciences.
Space-based measurements from small satellites also have great potential to advance discovery and understanding in geospace and atmospheric sciences in many other ways.
To take full advantage of these developments, NSF is soliciting research proposals centered on small satellite missions.
The overarching goal of the program is to support the development, construction, launch, operation, and data analysis of small satellite science missions to advancegeospace and atmospheric research.
Equally important, it will provide essential opportunities to train the next generation of experimental space scientists and aerospace engineers.
To facilitate launch of the satellites as secondary payloads on existing missions, the focus of the program is on CubeSat-based satellites.
Launch of the satellites will mainly be through the standardized CubeSat deployment system, the Poly Picosatellite Orbital Deployer (P-POD).
Launch of the P-PODS will be as auxiliary payloads on DOD, NASA, or commercial launches.
This will be arranged after selection and is not part of this solicitation.
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Titan’s Seas Get an Earthly Stand-In as Robot Explores Chilean Lake [Slide Show]
The Planetary Lake Lander is testing autonomous exploration technologies for a future mission to Saturn’s most intriguing moon
Credits: Katie Worth
Science Extended: The team takes a break on a slab of granite to admire the view of Echuarren glacier. In November NASA announced the project’s funding would be extended by another year.
Chilly in Chile: Temperatures at the high-altitude camp dropped sharply at night, requiring engineer Trey Smith, center, and colleagues to bundle up as they worked past dusk in the tent dubbed the Robodome.
Eyes Underwater: Researcher Cristian Tambley of logistics company CampoAlto attaches a camera to an improvised submarine. The device recorded algae growing at 60 meters below the surface. Flora can thrive even at that depth because of the extraordinary transparency of the lake, an effect of accelerated deglaciation.
Titan Ahoy: The Lake Lander temporarily gains a deck chair and an electric motor for a cruise across the lake. The proposed Titan Mare Explorer would float passively on currents, but could aim its cameras and instruments to focus on interesting phenomena, and then use simple data analysis to select the information it sent back to Earth.
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Shoving Off: Principal Investigator Nathalie Cabrol waves as the science team embarks on a data-collection mission. In addition to developing technology, researchers are exploring the effects of climate change on the lake.
Moonlit Maintenance: Engineers Liam Pedersen and Susan Lee of NASA’s Intelligent Robotics Group replace the Lake Lander’s computer after maintenance. The team is using the probe to develop smarter space exploration technology.
Andean Expedition: This month researchers travelled to the glacial lake in central Chile where the Lake Lander has floated for three years. Equipment was transported to the remote camp by burro.
The Floating Robot: Scientists and engineers from NASA and the SETI Institute built the Planetary Lake Lander to test technologies that could one day help explore the seas of Saturn’s moon Titan.
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A newly published study describes how a group of Harvard scientists were able to create quantum bits and store information in them for nearly two seconds at room temperature by using a pair of impurities in ultra-pure, laboratory-grown diamonds.
It’s a challenge that’s long been one of the holy grails of quantum computing: how to create the key building blocks known as quantum bits, or qubits, that exist in a solid-state system at room temperature.
Most current systems, by comparison, rely on complex and expensive equipment designed to trap a single atom or electron in a vacuum and then cool the entire system to close to absolute zero.
A group of Harvard scientists, led by Professor of Physics Mikhail Lukin and including graduate students Georg Kucsko and Peter Maurer and postdoctoral researcher Christian Latta, say they’ve cracked the problem, and they did it by turning to one of the purest materials on Earth: diamonds.
Using a pair of impurities in ultra-pure, laboratory-grown diamonds, the researchers were able to create quantum bits and store information in them for nearly two seconds, an increase of nearly six orders of magnitude over the life span of earlier systems. The work, described in the June 8 issue of Science, is a critical first step in the eventual construction of a functional quantum computer, and has a host of other potential applications.
“What we’ve been able to achieve in terms of control is quite unprecedented,” Lukin said. “We have a qubit, at room temperature, that we can measure with very high efficiency and fidelity. We can encode data in it, and we can store it for a relatively long time. We believe this work is limited only by technical issues, so it looks feasible to increase the life span into the range of hours. At that point, a host of real-world applications become possible.”
In addition to a practical quantum computer, Lukin envisions the system being used in applications that include “quantum cash” (a payment system for bank transactions and credit cards that relies on the coding of quantum bits to thwart counterfeiters) and quantum networks (a highly secure communications method that uses quantum bits to transmit data).
“This research is an important step forward in research toward one day building a practical quantum computer,” said Kucsko, who works in Lukin’s lab and is one of two first authors of the paper. “For the first time, we have a system that has a reasonable timescale for memory and simplicity, so this is now something we can pursue.”
The groundwork for Lukin’s breakthrough was laid several years ago, when researchers discovered that nitrogen-vacancy (NV) centers, atomic-scale impurities in lab-grown diamonds, behave in the same way as single atoms. Like individual atoms, each center possesses a spin, which can be polarized, similar to on a bar magnet. Using lasers, researchers are able not only to control the spin, but to detect its orientation as it changes over time.
But the idea of using the NV centers to form the backbone of a quantum computer simply wasn’t practical, largely because they can only hold data for about one-millionth of a second before their quantum properties — and any data they may have held — are lost.
The culprit, Lukin said, was another impurity in the diamond crystal.
In initial experiments, the team used diamonds that contained 99 percent carbon-12 atoms, which have no spin. The remainder, however, was made up of carbon-13 atoms, a tricky isotope that contains a spin in the atom’s nucleus. Though weak, the interaction with those spins was causing the NV centers’ short life spans.
With this latest research, however, Lukin and his team turned what was once a challenge — the interaction between the NV center and carbon-13 atoms — to their advantage.
“The nuclear spin of the carbon-13 makes an ideal quantum bit, because they are very isolated,” Lukin said. “Because they interact with so few outside forces, they have relatively long coherence times. Of course, the same properties that make them ideal qubits also make them difficult to measure and manipulate.”
The solution Lukin and his team came up with was surprisingly elegant. Rather than trying to find a way to measure the spin of the carbon atoms, they used the NV center to do it for them.
Working with researchers at Element Six, a British-based company that specializes in manufacturing artificial diamonds, they developed a new technique to create crystals that were even more pure: 99.99 percent carbon-12. Researchers then bombard the crystal with nitrogen to create the NV center, which interacts with a nearby carbon-13 atom.
The result of that interaction is that the NV center mirrors the state of the carbon atom, meaning researchers can encode a bit of information into the spin of the atom, then “read” that data by monitoring the NV center.
“The system we’ve developed uses this very local probe, the NV center, to allow us to monitor that spin,” Lukin said. “As a result, for the first time, we can encode a bit of information into that spin, and use this system to read it out.”
However, encoding information into the spin of the carbon-13 atom and reading it out using the NV center is only a step on the road to a quantum computer. To truly be useful, researchers had to determine how to take advantage of the atom’s quantum properties — that is, its ability to occupy two states simultaneously.
That ability to be in two states at the same time is a key principle of quantum computers. As opposed to traditional computers, which encode bits of information as either zero or one, quantum computers rely on atomic-scale quantum mechanics to give quantum bits both values at once. That property, in theory, allows quantum computers to perform multiple computations in parallel, making them vastly more powerful than traditional computers, which perform operations in sequence.
The solution, Lukin explained, was a two-step process.
The first step is to cut the connection between the NV center and the carbon atom. Using massive amounts of laser light, researcher are able to effectively keep the NV center occupied and prevent it from interacting with the carbon atom. In step two, the diamond crystal is bombarded with a specific set of radio frequency pulses, suppressing the interaction between the carbon-13 atom and any nearby atoms.
“By limiting interactions with the carbon-13 atom, we can extend the life of the qubit and hold the data for longer,” Lukin said. “The end result is that we’re able to push the coherence time from a millisecond to nearly two seconds.”
Researchers at the California Institute of Technology and the Max-Planck-Institut für Quantenoptik also participated in the research. Funding was provided by the National Science Foundation, the Center for Ultracold Atoms, the Defense Advanced Research Projects Agency, Element 6, the Packard Foundation, the European Union, the Swiss National Science Foundation, and the Sherman Fairchild Foundation.
Source: Peter Reuell, Harvard Staff Writer; Harvard Gazette
Image: Stephanie Mitchell/Harvard Staff Photographer | <urn:uuid:8e1c05c2-cafe-475c-8363-1d349692e247> | 3.375 | 1,528 | News Article | Science & Tech. | 37.311606 | 95,483,830 |
Cambrian Genetics Says 'Print Your Own Genetically Unique Creature'
Austen Heinz, founder of Cambrian Genomics, has attracted the attention of investors and bioethicists with his plan to let everyone design new creatures and then print out their DNA quickly and cheaply.
(Rose bioengineered to glow)
“Anyone in the world that has a few dollars can make a creature, and that changes the game,” Heinz said. “And that creates a whole new world.”
The 31-year-old CEO has a deadpan demeanor that can be hard to read, but he is not kidding. In a makeshift laboratory in San Francisco, his synthetic biology company uses lasers to create custom DNA for major pharmaceutical companies. Its mission, to “democratize creation” with minimal to no regulation, frightens bioethicists as deeply as it thrills Silicon Valley venture capitalists.
With the latest technology and generous funding, a growing number of startups are taking science and medicine to the edge of science fiction. In the works or on the market are color-changing flowers, cow-free milk, animal-free meat, tests that detect diseases from one drop of blood and pills that tell doctors whether you have taken your medicine.
But few founders are pushing the technical and ethical boundaries of science as far as Heinz, who told the Wall Street Journal, “I can’t believe that after 10 or 20 years people will not design their children digitally.” At a recent conference in Vienna, he said, “We want to make totally new organisms that have never existed.”
SF fans know that a very early version of this idea appeared in HG Wells' 1896 blockbuster The Island of Dr. Moreau:
It is not simply the outward form of an animal which I can change. The physiology, the chemical rhythm of the creature, may also be made to undergo an enduring modification... You begin to see that it is a possible thing ... to change it in its most intimate structure.
At another point, Wells makes this remark about the ethics of Dr. Moreau:
The thing before you is no longer an animal, a fellow-creature, but a problem! Sympathetic pain,--all I know of it I remember as a thing I used to suffer from years ago. I wanted--it was the one thing I wanted--to find out the extreme limit of plasticity in a living shape."
"But," said I, "the thing is an abomination--"
"To this day I have never troubled about the ethics of the matter," he continued. "The study of Nature makes a man at last as remorseless as Nature.
Via SF Gate.
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Brain cells get tweaked 'on the go'
News Sep 11, 2015
Researchers from the MRC Centre for Developmental Neurobiology (MRC CDN) at the Institute of Psychiatry, Psychology & Neuroscience (IoPPN), King's College London, have discovered a new molecular 'switch' that controls the properties of neurons in response to changes in the activity of their neural network. The findings, published in Science, suggest that the 'hardware' in our brain is tuneable and could have implications that go far beyond basic neuroscience - from informing education policy to developing new therapies for neurological disorders such as epilepsy.
Computers are often used as a metaphor for the brain, with logic boards and microprocessors representing neural circuits and neurons, respectively. While this analogy has served neuroscience well in the past, it is far from correct, according to the researchers from King's. They suggest that the brain is a highly dynamic, self-organizing system, in which internal and external influences continuously shape information processing 'hardware' by mechanisms not yet understood, and in a way not achieved by computers.
Researchers from the MRC CDN, led by Professor Oscar Marín, have shed light on this problem by discovering that some neurons in the cerebral cortex can adapt their properties in response to changes in network activity - such as those observed during learning of a motor task. The authors studied two apparently different classes of fast-spiking interneurons, only to discover that they were actually looking at the same piece of 'hardware' which had the ability to oscillate between two different ground states. The authors also identified the molecular factor responsible for tuning the properties of these cells, a transcription factor - a protein able to influence gene expression - known as Er81.
Fast-spiking interneurons are part of a general class of neurons whose primary role is regulating the activity of the principal cells of the cerebral cortex, known as pyramidal cells. The cerebral cortex is outer layer of the brain and is associated with cognition, language and memory.
'Our findings explain the underlying mechanisms behind the dynamic regulation of the identity of interneurons', said Nathalie Dehorter of the MRC CDN and first author of the study. 'The results of this study support the notion that activity plays a prominent role in the specification of neuronal properties, which adapt in response to internal and external influences to encode information. In other words, that our 'hardware' is tuneable, at least to some extent.'
Understanding the dynamic mechanisms that lead to the emergence of brain functions through the development and continuous remodeling of neural circuits, and the constraints that disease and ageing impose to this multi-modal plasticity has important implications that go beyond fundamental neuroscience, from education policies to brain repair.
Professor Oscar Marín, last author from the MRC CDN, said: 'Our study demonstrates the tremendous plasticity of the brain, and how this relates to fundamental processes such as learning. Understanding the mechanisms that regulate this plasticity, and why it tends to dissipate when we age, has enormous implications that go beyond fundamental neuroscience, from informing education policies to developing new therapies for neurological disorders such as epilepsy.'
Note: Material may have been edited for length and content. For further information, please contact the cited source.
Marin O et al. Tuning of fast-spiking interneuron properties by an activity-dependent transcriptional switch.. Science, Published September 11 2015. doi: 10.1126/science.aab3415
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Understanding the mechanisms of insect choice could help scientists glean insights into and develop strategies for the treatment of human disorders where motivation goes awryREAD MORE | <urn:uuid:9f5e32b4-ff6b-4e9e-afc2-a324471ff6ea> | 2.671875 | 834 | News Article | Science & Tech. | 20.587285 | 95,483,925 |
- Ocean Wise (formerly Vancouver Aquarium Marine Science Centre)
- Eric Solomon
- PO Box 3232
- Vancouver, BC V6B3X8 Canada
Project description for Ocean Wise Scientific Diving Field Research on Board One Ocean Expeditions Cruise (125352)While there is good knowledge of what lives on land in the Canadian Arctic and about marine mammals and fish, very little is known about what lives on or near the bottom of the ocean in many places in the High Arctic. Ocean Wise research scuba divers would like to dive in various locations around Cornwallis, Devon, Somerset, southern Ellesmere and North Baffin Islands to take photographs and video of life at the bottom and record what they see in order to identify and catalogue what is there. Our divers have been offered the opportunity to travel aboard the One Ocean Expeditions ship, the Akademik Ioffe, from August 14 to August 23 and will conduct their dives at the ship’s regular planned stops. The information will help us better understand what lives in these coastal areas and to track over time how things change. They will also collect some (1-5 of any one species) samples of fish and invertebrates (no mammals or large fish) in order to get their DNA, which is used to help identify species. They will record water temperature and other conditions as well. Some invertebrates and fish may also be collected for use by the Vancouver Aquarium for displays and exhibits. The dives will be non-destructive. They will collect a small number of fish and invertebrates by hand and using hand-held nets. Examples include anemones, sea stars urchins, etc.There will be four divers. They will dive from the Zodiacs, not from shore, and will not be using water or other resources. Planned locations include Dundas Harbour, Croker Bay and Maxwell Bay on Devon Island, Beechey Island, Port Leopold on Somerset Island, Elwin Inlet and Cape Hay on Baffin Island, and Craig Harbour on Ellesmere Island. They may also dive in Resolute Bay and offshore of Grise Fiord. Weather conditions might affect where they can dive.The information will be used to create a report that lists all the species identified at each location. We hope to continue this dive program and return to these sites each year to monitor for change, including the potential for non-native invasive species. This information will be made available to anyone interested. A copy of the report will be provided to the Resolute Bay HTA and Grise Fiord HTO. We hope to return to Resolute and Grise Fiord again next year and would be pleased to discuss the information in the report with the HTA/HTO and other interested community members.For further information, please contact Eric Solomon at firstname.lastname@example.org or 604-659-3496.
- Project Proposal (6)
- Public Notice (5)
- Comment Submissions (2)
- Conformity Determination (3)
Notifications sent: Received Comment submissions from Parties: Notice re comments received
NIRB 125352 / 16YN027: Comments Received for Ocean Wise’s “Scientific Diving Field Research on Board One Ocean Expeditions Cruise” Project Proposal
- Crown Indigenous and Northern Affairs Canada (CIRNAC)
- Parks Canada (PC)
All documents received and pertaining to this project proposal can be obtained from the NIRB’s online public registry at www.nirb.ca by using any of the following search criteria:
- Project Name: Ocean Wise Scientific Diving Field Research on Board One Ocean Expeditions Cruise
- NIRB File No.: 16YN027
- Application No.: 125352
Should you have any questions or require additional information, please contact Keith Morrison, Technical Advisor II, at 867-983-4617 or email@example.com.
Nunavut Impact Review Board
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Toll Free: 1-866-233-3033
As you are aware, on June 29, 2018 the Nunavut Impact Review Board (NIRB or Board) requested comments regarding Ocean Wise’s “Scientific Diving Field Research on Board One Ocean Expeditions Cruise” (NIRB: 16YN027; Associated with NIRB: 12AN025; NPC: 148877;
Associated with NPC: 148230, 148567 and 148846). The NIRB requested that these comments be provided by July 10, 2018.
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In this post we will discuss about one marquee example in asp.net. Also you can check out my previous posts on:
The marquee tag is a non-standard HTML element which causes text to scroll up, down, left or right automatically.
Below is an example:
<font face=”Merriweather” color=”Red”>
<marquee scrollamount=”3″ onmouseover=”stop();” onmouseout=”start();”>Win prizes like Hard Disk, Pen drives, T-Shirts etc. <a href=”https://www.enjoysharepoint.com/Write-Article-win-Prizes.aspx”>Click here </a>for more information</marquee>
Here we have given the font face and color in a <font> tag.
onmouseover, onmouseout attributes to stop and start scrolling on mouse over.
scrollamount is to control the speed of scrolling.
direction=”left/right/down/up” This attribute is required for the direction of the scroll. | <urn:uuid:07a2bb8f-61b7-41ae-b558-d0a369a91a61> | 2.625 | 239 | Tutorial | Software Dev. | 62.25596 | 95,483,965 |
On the Distribution of Hydrogen Sulphide in the Carbonate Oil and Gas Fields of the Russian Platform
The hydrogen sulphide content in the gases of the sulphate-carbonate complexes of the oil- and gas-bearing regions of the Russian plate varies over a wide range. Analysis of the regularities of these variations shows that the concentration of the hydrogen sulphide in the gases depends on the type of carbonate bodies, their thickness and areal extent. The most favourable conditions for hydrogen sulphide accumulation exist within large carbonate bodies, such as carbonate shelves (Pre-Caspian region) or barrier reef systems (Timano-Pechora region, etc.). Within the carbonate shelves the most sulphurous gases are confined to traps which lie farthest from the contact with terrigenous facies. i.e. when both the rocks containing the hydrocarbon pools and the rocks in contact with them vertically and laterally are of predominantly carbonate composition. The most sulphurous gases in the barrier-reef system are concentrated in their rear parts.
In thin carbonate beds and also in single reef bodies the content of hydrogen sulphide in gases, other things being equal, is less by a factor of 10 as compared with its content in gases which are confined to large carbonate bodies. This is likely to be due to the greater rate of sour gas diffusions from pools at the contact with terrigenous rocks and the greater influence on the gas composition of the inflow of non-sulphurous fluids from terrigenous rocks into carbonate traps.
The established regularities are important for subdividing regions with sulphate-carbonate complexes into zones of presumed higher or lower hydrogen sulphide concentrations prior to the discovery of the hydrocarbon pools.
KeywordsHydrogen Sulphide Terrigenous Rock Hydrocarbon Accumulation Lower Devonian Russian Platform
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- Anisimov L A (1976) Geochemistry of H2S and formation of highly sulfurous gas pool. Nedra, Moscow, 160 ppGoogle Scholar
- Belenitskaya G A, Gurevich M S (1978) Regularities in distribution and criteria of prognosis of gaseous sulphur deposits. Sov Geol 2: 3–20Google Scholar
- Garetsky K G, Kiryuchin L G, Kapustin I N, Konishev V S (1990) Noncompensated troughs of the Vostochno European platform. Nauka i Tekchnika, Minsk. 102 pGoogle Scholar
- Krouse H R (1979) Stable isotope geochemistry of nonhydrocarbon constituents of natural gas. 10th World Petroleum Congr Bucharest. PD 16, pp 1–7Google Scholar
- Matvievskaya N D (1981) Oil and gas potential of the Upper Devonian carbonate complex of the Timano-Pechora province. Geol Nefti I Gaza 3: 6–13Google Scholar
- Orr W L (1974) Changes in sulphur content and isotropic ratios of sulphur during petroleum maturation study of Big Horn Basin Paleozoic oils. AAPG Bull 58: 2295–2318Google Scholar
- Pankina R G, Mekhtieva V L (1981) The origin of H2S and CO2 in hydrocarbon accumulations. Geol Nefti I Gaza 12: 44–48Google Scholar
- Pankina R G, Dakhnova M V Mekhtieva V L (1984) Prediction of acid component content (H2S and CO2) in the hydrocarbon accumulations from geologic-geochemical criteria. In: Geochemical criteria of evaluation of the oil and gas accumulation magnitude and prognose of the hydrocarbon fluids quality in a zone of accumulation. VNIGNI, Moscow, pp 139–143Google Scholar | <urn:uuid:f9739036-11bd-4cf4-b140-3789b906ad41> | 2.78125 | 811 | Academic Writing | Science & Tech. | 36.383963 | 95,483,980 |
Coherence (signal processing)
The spectral coherence is a statistic that can be used to examine the relation between two signals or data sets. It is commonly used to estimate the power transfer between input and output of a linear system. If the signals are ergodic, and the system function linear, it can be used to estimate the causality between the input and output.
Definition and Formulation
where Gxy(f) is the Cross-spectral density between x and y, and Gxx(f) and Gyy(f) the autospectral density of x and y respectively. The magnitude of the spectral density is denoted as |G|. Given the restrictions noted above (ergodicity, linearity) the coherence function estimates the extent to which y(t) may be predicted from x(t) by an optimum linear least squares function.
Values of coherence will always satisfy . For an ideal constant parameter linear system with a single input x(t) and single output y(t), the coherence will be equal to one. To see this, consider a linear system with an impulse response h(t) defined as: , where * denotes convolution. In the Fourier domain this equation becomes , where Y(f) is the Fourier transform of y(t) and H(f) is the linear system transfer function. Since, for an ideal linear system: and , and since is real, the following identity holds,
However, in the physical world an ideal linear system is rarely realized, noise is an inherent component of system measurement, and it is likely that a single input, single output linear system is insufficient to capture the complete system dynamics. In cases where the ideal linear system assumptions are insufficient, the Cauchy–Schwarz inequality guarantees a value of .
If Cxy is less than one but greater than zero it is an indication that either: noise is entering the measurements, that the assumed function relating x(t) and y(t) is not linear, or that y(t) is producing output due to input x(t) as well as other inputs. If the coherence is equal to zero, it is an indication that x(t) and y(t) are completely unrelated, given the constraints mentioned above.
The coherence of a linear system therefore represents the fractional part of the output signal power that is produced by the input at that frequency. We can also view the quantity as an estimate of the fractional power of the output that is not contributed by the input at a particular frequency. This leads naturally to definition of the coherent output spectrum:
provides a spectral quantification of the output power that is uncorrelated with noise or other inputs.
Here we illustrate the computation of coherence (denoted as ) as shown in figure 1. Consider the two signals shown in the lower portion of figure 2. There appears to be a close relationship between the ocean surface water levels and the groundwater well levels. It is also clear that the barometric pressure has an effect on both the ocean water levels and groundwater levels.
Figure 3 shows the autospectral density of ocean water level over a long period of time.
As expected, most of the energy is centered on the well-known tidal frequencies. Likewise, the autospectral density of groundwater well levels are shown in figure 4.
It is clear that variation of the groundwater levels have significant power at the ocean tidal frequencies. To estimate the extent at which the groundwater levels are influenced by the ocean surface levels, we compute the coherence between them. Let us assume that there is a linear relationship between the ocean surface height and the groundwater levels. We further assume that the ocean surface height controls the groundwater levels so that we take the ocean surface height as the input variable, and the groundwater well height as the output variable.
The computed coherence (figure 1) indicates that at most of the major ocean tidal frequencies the variation of groundwater level at this particular site is over 90% due to the forcing of the ocean tides. However, one must exercise caution in attributing causality. If the relation (transfer function) between the input and output is nonlinear, then values of the coherence can be erroneous. Another common mistake is to assume a causal input/output relation between observed variables, when in fact the causative mechanism is not in the system model. For example, it is clear that the atmospheric barometric pressure induces a variation in both the ocean water levels and the groundwater levels, but the barometric pressure is not included in the system model as an input variable. We have also assumed that the ocean water levels drive or control the groundwater levels. In reality it is a combination of hydrological forcing from the ocean water levels and the tidal potential that are driving both the observed input and output signals. Additionally, noise introduced in the measurement process, or by the spectral signal processing can contribute to or corrupt the coherence.
Extension to non-stationary signals
If the signals are non-stationary, (and therefore not ergodic), the above formulations may not be appropriate. For such signals, the concept of coherence has been extended by using the concept of time-frequency distributions to represent the time-varying spectral variations of non-stationary signals in lieu of traditional spectra. For more details, see.
- "Frequency domain", Wikipedia, 2018-04-18, retrieved 2018-07-10
- J. S. Bendat, A. G. Piersol, Random Data, Wiley-Interscience, 1986
- http://www.fil.ion.ucl.ac.uk/~wpenny/course/course.html, chapter 7
- L.B. White and B. Boashash, "Cross Spectral Analysis of Nonstationary Processes", IEEE Transactions on Information Theory, Vol. 36, No. 4, pp. 830-835, July 1990. | <urn:uuid:41e71592-5e9a-4fc3-9f5f-a5a0afa5efee> | 3.4375 | 1,224 | Knowledge Article | Science & Tech. | 42.246325 | 95,483,992 |
Metrical Aspects of Two-Center Hydrogen Bonds
The donor and acceptor groups found in biological structures which form O — H ··· O bonds are given in Box 6.1. The C — OH ⋯ O hydrogen bonds are the primary intermolecular cohesive force between the carbohydrate molecules, water, and carboxylic acids. They occur extensively in the structures of cyclodextrins, polysaccharides, glycolipids, and glycoproteins. The OWH ··· O bonds are important in the ices, in hydrated crystal structures, and in the hydration shell of all biological molecules.
KeywordsNeutron Diffraction Acceptor Group Neutron Diffraction Data Neutron Diffraction Analysis Short Hydrogen Bond
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This web site provides a complete source of graphical weather information. It is intended to satisfy the needs of the weather professional but can be a tool for the casual user as well. The graphics and data are displayed as a meteorologist would expect to see. For the novice user, there are detailed explanationsto guide one through the various plots, charts and images. The data on this site are provided from the National Weather Service via the National Oceanic and Atmospheric Administration PORT satellite data service. Available weather maps include: visible satellite image, Enh IR satellite image, satellite surface map, United States radar summary, Eta model forecast, Medium Range Forecast 10 day forecast, and the Rapid Update Cycle model. Also available are links to hurricane data and an archive of images.
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Subject: Geoscience:Atmospheric Science, Atmospheric Science:Climatology Resource Type: Audio/Visual:Images/Illustrations Grade Level: Graduate/Professional, College Upper (15-16), High School (9-12), College Lower (13-14) Data Derived: Data Derived Topics: Climate, Atmosphere Theme: Teach the Earth:Course Topics:Atmospheric Science, Teach the Earth:Incorporating Societal Issues:Climate Change
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Generate three random numbers to determine the side lengths of a triangle. What triangles can you draw?
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A game to make and play based on the number line.
Move your counters through this snake of cards and see how far you can go. Are you surprised by where you end up?
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Make a spiral mobile.
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How can you make an angle of 60 degrees by folding a sheet of paper twice?
Interior angles can help us to work out which polygons will tessellate. Can we use similar ideas to predict which polygons combine to create semi-regular solids?
Use the tangram pieces to make our pictures, or to design some of your own!
You could use just coloured pencils and paper to create this design, but it will be more eye-catching if you can get hold of hammer, nails and string.
The triangle ABC is equilateral. The arc AB has centre C, the arc BC has centre A and the arc CA has centre B. Explain how and why this shape can roll along between two parallel tracks.
Use the interactivity to play two of the bells in a pattern. How do you know when it is your turn to ring, and how do you know which bell to ring?
Delight your friends with this cunning trick! Can you explain how it works?
Use the interactivity to listen to the bells ringing a pattern. Now it's your turn! Play one of the bells yourself. How do you know when it is your turn to ring?
A jigsaw where pieces only go together if the fractions are equivalent.
I start with a red, a blue, a green and a yellow marble. I can trade any of my marbles for three others, one of each colour. Can I end up with exactly two marbles of each colour?
I start with a red, a green and a blue marble. I can trade any of my marbles for two others, one of each colour. Can I end up with five more blue marbles than red after a number of such trades?
Make an equilateral triangle by folding paper and use it to make patterns of your own.
A game in which players take it in turns to choose a number. Can you block your opponent?
Can you use small coloured cubes to make a 3 by 3 by 3 cube so that each face of the bigger cube contains one of each colour?
Make your own double-sided magic square. But can you complete both sides once you've made the pieces?
These models have appeared around the Centre for Mathematical Sciences. Perhaps you would like to try to make some similar models of your own.
Exploring balance and centres of mass can be great fun. The resulting structures can seem impossible. Here are some images to encourage you to experiment with non-breakable objects of your own.
Make some celtic knot patterns using tiling techniques
Galileo, a famous inventor who lived about 400 years ago, came up with an idea similar to this for making a time measuring instrument. Can you turn your pendulum into an accurate minute timer?
It might seem impossible but it is possible. How can you cut a playing card to make a hole big enough to walk through?
Can you describe what happens in this film?
How many differently shaped rectangles can you build using these equilateral and isosceles triangles? Can you make a square?
Here is a chance to create some Celtic knots and explore the mathematics behind them.
This article for students gives some instructions about how to make some different braids.
This article for pupils gives an introduction to Celtic knotwork patterns and a feel for how you can draw them.
As part of Liverpool08 European Capital of Culture there were a huge number of events and displays. One of the art installations was called "Turning the Place Over". Can you find our how it works?
Using your knowledge of the properties of numbers, can you fill all the squares on the board?
In this article for teachers, Bernard uses some problems to suggest that once a numerical pattern has been spotted from a practical starting point, going back to the practical can help explain. . . .
Which of the following cubes can be made from these nets?
Make a clinometer and use it to help you estimate the heights of tall objects.
How is it possible to predict the card?
Time for a little mathemagic! Choose any five cards from a pack and show four of them to your partner. How can they work out the fifth?
What shape and size of drinks mat is best for flipping and catching?
What shape would fit your pens and pencils best? How can you make it?
How does the time of dawn and dusk vary? What about the Moon, how does that change from night to night? Is the Sun always the same? Gather data to help you explore these questions.
Can Jo make a gym bag for her trainers from the piece of fabric she has?
Build a scaffold out of drinking-straws to support a cup of water
Design and construct a prototype intercooler which will satisfy agreed quality control constraints.
What shapes should Elly cut out to make a witch's hat? How can she make a taller hat?
More Logo for beginners. Learn to calculate exterior angles and draw regular polygons using procedures and variables.
What happens when a procedure calls itself? | <urn:uuid:7321e976-e1fe-4d68-91fd-3c7382d9670c> | 3.609375 | 1,254 | Content Listing | Science & Tech. | 66.762445 | 95,484,058 |
Tropical climates are found in areas that lie close to the equator. Here the sun shines intensely. Within tropical climates, there are three groups: tropical wet; tropical wet and dry; and tropical monsoon. Tropical wet regions, also known as rain forests, have the most predictable weather on earth. Here, everyday is pretty much the same. You can expect lots of rain, warm nights and hot days. The seasons change only slightly.
Monsoon climates have winds that reverse every six months. For example, in India the winds blow in from the sea during the summer, bringing buckets of heavy rain. The winds reverse in the winter blowing from land to sea. Winters are dry here. Many people in monsoon climates rely on the monsoons to bring water for their crops. Monsoons sometimes bring too much rain, causing flooding and mudslides.
Tropical wet and dry climates have three seasons: one season is cool and dry; another season is hot and dry; the third season is wet and hot. Some years, the rains here are light. When this happens, there is not enough food or water for animals and people.
Fun Facts About Tropical Climates for Kids
- Hawaii has a tropical rainforest climate.
- Monsoon climates can be found in southern Asia and West Africa.
- Africa’s Serengeti Plain is an example of a wet dry tropical climate.
- The rain forest climate sounds ideal, but it is very humid here and there are lots of mosquitoes and bugs.
- In India, the monsoon rains not only water crops, but they power electric plants. If the rains are scarce, electricity becomes expensive.
Tropical Climates Vocabulary
- Predictable: reliable, same, consistent
- Expect: look forward to
- Mudslides: sheets of mud slide down a hill
- Humid: wet, moist
- Scarce: rare
All About Tropical Climates Video for Kids
Watch this awesome video for kids about Tropical Climates:
Tropical Climates Q&A
Question: Are monsoons dangerous?
Answer: Sometimes they are. In the city of Mumbai, India, for example, the streets flood every year with over 1 foot of water. In 2005, a strong monsoon hit India. Mumbai got 40 inches of rain in one day. Buildings were destroyed and people drowned.
Enjoyed the Earth Science for Kids all about Tropical Climates info? Take the FREE & fun all about Tropical Climates quiz and download FREE all about Tropical Climates worksheet for kids. For lengthy info click here.
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Molecular Characterization of Transformed Plants
The generation of genetically transformed plants is central to, and has indeed revolutionized, plant molecular biology. This is true for studies at both the fundamental and more applied levels of research. For researchers interested in unravelling the roles of specific genes in particular pathways of growth and development, the introduction into plants of foreign genes and gene promoters linked to reporter genes allows the detailed study of the temporal, spatial and quantitative expression of plant genes and the activities of associated regulatory sequences. In our own laboratory, we use these techniques in a programme of insertional mutagenesis to identify developmentally interesting genes (Topping et al. 1991; Lindsey et al. 1993; Topping et al. 1994). In the more applied area of genetic engineering, which is directed towards crop improvement, the introduction of novel genes encoding, for example, resistance to various pests and herbicides into economically important species, is in the long term likely to develop into a major branch of the plant breeding industry (Lindsey 1992). There are several well-characterized and very successful methods which are currently being employed to introduce specific genes and gene regulatory sequences into plants and these are described in Chapter 8 of this book.
KeywordsSelectable Marker Gene Plant Molecular Biology Crude Cell Extract Microprojectile Bombardment Sterile Double Distil Water
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- Jefferson RA, Kavanagh TA, Bevan MW (1987) GUS fusions: ß-glucuronidase as a sensitive and versatile gene fusion marker in higher plants. EMBO J 6:3301–3307Google Scholar
- Nagy F, Odell JT, Morelli G, Chua N-H (1985) Properties of expression of the 35S promoter from CaMV in transgenic tobacco plants. In: Zaitlin M, Day P, Hollaender A (eds) Biotechnology in plant science: relevance to agriculture in the eighties. Academic Press, Orlando, pp 227–235CrossRefGoogle Scholar
- Reynaerts A, De Block M, Hernalsteens J-P, van Montagu M (1988) Selectable and screenable markers. In: Gelvin SB, Schilperoort RA (eds) Plant molecular biology manual. Kluwer, Dordrecht A9.T-16Google Scholar
- Sambrook J, Fritsch EF, Maniatis T (eds) (1989) Molecular cloning: a laboratory manual 2nd edn. Cold Spring Harbor Laboratory Press, Cold Spring HarborGoogle Scholar
- Stomp A-M (1990) Use of X-Gluc for histochemical localisation of glucuronidase. In: Editorial comments. United State Biochemical, Cleveland, p 5Google Scholar | <urn:uuid:1edb8d71-9ac5-49fa-bb05-52c8c3f3213f> | 2.8125 | 576 | Truncated | Science & Tech. | 26.737045 | 95,484,073 |
Beyond that timespan, the amount of the original C formed by irradiation of nitrogen by neutrons from the spontaneous fission of uranium, present in trace quantities almost everywhere.For these samples, other dating methods must be used.As scientists who study earth’s (relatively) modern history rely on this measurement tool to place their findings in the correct time period, the discovery that it is unreliable could put some in a quandary.For instance, remnants of organic matter formerly held up as solid evidence of the most recent, large-scale global warming event some 40,000 years ago may actually date back far earlier to a previous ice age.The Geologic Time Scale was originally laid out using relative dating principles.
Their recent analysis of sediment from the largest freshwater lake in northeast China showed that its carbon clock stopped ticking as early as 30,000 years ago, or nearly half as long as was hitherto thought.
Carbon dating has a certain margin of error, usually depending on the age and material of the sample used.
Carbon-14 has a half-life of about 5730 years, and therefore it is used to date biological samples up to about 60,000 years in the past.
Prior to that, they had to depend on more rudimentary and imprecise methods, such as counting the number of rings on a cross-section of tree trunk.
This all changed in the 1940s when US chemist Willard Libby discovered that carbon-14, a radioactive isotope, could be used to date organic compounds. | <urn:uuid:ceba9c02-800e-4726-9303-24faada9cbe5> | 4.15625 | 313 | Knowledge Article | Science & Tech. | 40.071313 | 95,484,083 |
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Spins wobble (or precess) about the axis of the BO field so as to describe a cone. This is called precession. Spinning protons are like dreidles spinning about their axis. Precession corresponds to the gyration of the rotating axis of a spinning body about an intersecting axis.
The resonance frequency, called Larmor frequency (ω0) or precessional frequency, is proportional to the main magnetic field strength: ω0 = γ B0. | <urn:uuid:f0f9043f-ac3e-4f28-8300-4d2ae59273ba> | 2.671875 | 151 | Knowledge Article | Science & Tech. | 54.552574 | 95,484,092 |
This graphical scientific calculator purely written in C programming language. It uses small functions to draw buttons on the screen and perform scientific operations like conversion, logrithm, and other operations. Every operation can be performed using the mouse buttons as well as keyboard. It can perform almost all the functions shown on the screen except few functins which will be implemented in the next version of this calculator code.
Before compilation make sure you change the line 460 ( initgraph(&gdriver, &gmode, “f:\\tc\\bgi”);) to show the actual path of the graphics library on your machine i.e. bgi folder of your turbo C/C++ compiler installation.
Here are the few functions this calculator performs.
- It performs the conversion from decimal to (Binary, Octal and Hex decimal) values.
- Calculates Sign, Tangant and Sec, Coses, Cot.
- Log, Antilog, Exponent, power values.
- Also it can store numbers in memory, find the square root of any number.
This software is provided by MYCPLSU with the source code, you are free to use this code as you need and change the code.
Calculator (110.9 KiB, 30,757 hits) | <urn:uuid:0ed7fcba-dc0d-4f58-86ad-7de44c8d4df5> | 2.6875 | 268 | Product Page | Software Dev. | 52.574932 | 95,484,097 |
Washington: NASA next week launches its first dedicated oceanographic research mission to study the ice cover in the Arctic Ocean, officials have said.
The "Impacts of Climate on Ecosystems and Chemistry of the Arctic Pacific Environment" mission, or ICESCAPE, will put to sea on the US Coast Guard icebreaker, The Healy, on June 15.
More than 40 scientists will spend five weeks at sea on board The Healy, sampling the physical, chemical and biological properties of the ocean waters and sea ice, to try to determine how changes in the Arctic are affecting the ocean`s chemistry and ecosystem.
Last year, a study using data from a NASA satellite showed that Arctic sea ice thinned dramatically between the winters of 2004 and 2008, with thick older ice shrinking by the equivalent of Alaska`s land area.
Arctic sea ice is now "just a thin veneer five to 10 feet thick that is really susceptible to climate change," Don Perovich, one of the chief scientists on ICESCAPE, said yesterday.
One of the key efforts of the ICESCAPE mission will be to see how changes in the Arctic could be altering the ocean`s ability to absorb carbon from the atmosphere.
The greenhouse gas carbon dioxide is a leading cause of global warming, and to be able to predict future climate change, scientists need to know how the carbon cycle works in different parts of the world.
ICESCAPE will concentrate on the Chukchi and Beaufort seas off Alaska, which scientists say are particularly vulnerable to global warming.
An automated microscope on The Healy will take continuous digital photographs of phytoplankton cells to observe how many different species are in the Arctic waters and ice.
Floats with near-real time satellite communication will be placed in the ocean to measure temperature and biological and optical properties, and the scientists will work on the sea ice several hundred meters from the ship, studying the condition of the ice and sampling the ocean ecosystem. | <urn:uuid:2b0f7d05-62f3-4521-8d90-4f4720166bce> | 3.703125 | 407 | News Article | Science & Tech. | 27.384357 | 95,484,114 |
This web page gives a brief introduction to the double slit experiment in quantum mechanics illustrated by a java applet. The applet is a simulation of a 2D interference experiment with user changeable slit size, detector position, and whether there is one or two slits. The description of the experiment gives a brief introduction to the concepts of the wavefunction providing probabilities and measurements causing a collapse of the wavefunction.
%0 Electronic Source %A Yalabik, Cemal %D September 12, 2006 %T The double slit experiment and the collapse of the wavefunction %V 2018 %N 23 July 2018 %8 September 12, 2006 %9 application/java %U http://www.fen.bilkent.edu.tr/~yalabik/applets/collapse.html
Disclaimer: ComPADRE offers citation styles as a guide only. We cannot offer interpretations about citations as this is an automated procedure. Please refer to the style manuals in the Citation Source Information area for clarifications. | <urn:uuid:c8de8aad-ff23-447b-9922-08e72a7ea3b7> | 2.921875 | 208 | Knowledge Article | Science & Tech. | 40.714091 | 95,484,119 |
why do we need to maintain biodiversity
Why do we need to protect biodiversity? We need ants to survive, but they don't need us at all. Prof. E. O Wilson, in,
Chivian, E. , Bernstein A. , Center for Health and the Global Environment, Harvard Medical School, 2010 Biological diversity, or biodiversity, is the scientific term for the variety of life on Earth. It refers not just to species but also to ecosystems and differences in genes within a single species. Everywhere on the planet, species live together and depend on one another. Every living thing, including man, is involved in these complex networks of interdependent relationships, which are called ecosystems. Healthy ecosystems clean our water, purify our air, maintain our soil, regulate the climate, recycle nutrients and provide us with food. They provide raw materials and resources for medicines and other purposes. They are at the foundation of all civilisation and sustain our economies. It's that simple: we could not live without these Бecosystem servicesБ. They are what we call our natural capital. Biodiversity is the key indicator of the health of an ecosystem.
A wide variety of species will cope better with threats than a limited number of them in large populations. Even if certain species are affected by pollution, climate change or human activities, the ecosystem as a whole may adapt and survive. But the extinction of a species may have unforeseen impacts, sometimes snowballing into the destruction of entire ecosystems. European diversity is unique, but the loss of biodiversity has accelerated to an unprecedented level in Europe and worldwide. It has been estimated that the current global extinction rate is 100 to 1000 times higher than the natural rate. In Europe some 42% of European mammals are endangered, together with 15% of birds and 45% of butterflies and reptiles. To list just a few examples, the Arctic fox, the Iberian lynx and the red squirrel are all under serious threat. We are committed to halt biodiversity loss within the EU by 2020. Find out how with the. Tackling biodiversity loss makes economic sense. Find out why in. Nature and biodiversity are important for our health and well-being.
Find out more in the (, and ), or check out our factsheet on. We have been committed to the protection of biodiversity for a long time. Find out more about the. Why do we need biodiversity? Each and every species has a particular function in an ecosystem. Some species can capture energy in various forms: for example they can produce organic material, contribute to the nutritive system of the ecosystem, control soil erosion, act as a protection from pollution of the atmosphere and regulate the climate. Ecosystems contribute to improving the production of resources, as for example, soil fertility, pollination of plants and decomposition of vegetables and animals. They also carry out real services such as: purifying the air and water, moderating the climate and controlling the rain or drought, and other environmental disasters. Obviously all these important functions are fundamental for human survival. The more varied the ecosystem is, i. e. the greater the biodiversity, the greater its resistance to environmental stress will be. The loss of even only one species often can provoke a decrease in the capacity of the system to remain preserved in case of degradation.
Biodiversity is like a large tank, from which humans can draw food, pharmaceutical products and even cosmetics. This helps to better understand the importance of maintaining biodiversity, especially in the case of agrobiodiversity, i. e. diversity in agricultural productions. This regards the innumerable quantity of plants that help to feed and heal human beings. It can be found in the immense variety of cultures and animal species with specific nutritional characteristics, in animal breeds that have adapted to hostile environments, in insects that guarantee pollination and microorganisms that regenerate the soil used in agriculture. Biodiversity is an Бassurance Б for life on our Planet, and therefore must be protected at all costs, because it is a universal heritage that can offer immediate advantages to human beings. The economic importance of biodiversity for humans can be summarized as follows: Biodiversity offers food: harvests, silviculture, livestock and fish Biodiversity is fundamentally important in medicine.
A very large number of species of plants is used for medicinal purposes since very ancient times. An example is quinine, extracted from the cinchona tree (Cinchona calisaya and C. officinalis) that is used to fight malaria. Furthermore some scholars believe that 70% of anticancer drugs are derived from tropical forest plants. It seems that out of 250,000 species of known plants, only 5,000 have been studied for their possible medical applications. Biodiversity has a remarkable role also in the textile fibres manufacturing industry, wood for building and for the production of energy. Many industrial products are obtained thanks to biodiversity: lubricants, perfumes, paper, waxes and rubber, are all obtained from plants; and there are also products of animal origin such as wool, silk, leather, hides, etc. Biodiversity is a source of richness also in the sector of tourism and recreational activities: wild natural environments and the presence of animals in fact attract thousands of tourists from all over the world every year.
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why do we have to save endangered animals
why do we need to protect plants and animals
why do we need to protect animals
why do we need to save trees
why is biodiversity highest in tropical rainforest | <urn:uuid:5da291f8-971f-4b27-ba95-2e8fc1bd6ae0> | 3.359375 | 1,122 | Knowledge Article | Science & Tech. | 32.92636 | 95,484,134 |
Alyssa Carson is a name people will remember. She’s currently training to be one of the first people to go to Mars, specifically to build a colony there in a planned 2033 mission.
For arguments sake, though, let’s assume Congress manages to get behind Space Force and that the staggering amount of logistical and administrative concerns behind how this branch of the military would come to fruition suddenly became moot. What, then, is the point behind Space Force?
The near-Earth asteroid 2017 YE5 is actually two asteroids. Observations by two powerful telescopes helped astronomers confirm the asteroid’s binary nature.
NASA’s Dawn spacecraft is sending back incredible close-ups of the dwarf planet Ceres.
The spacecraft has been circling Ceres since 2015, and in June, it reached its lowest orbit yet, skimming the surface from just 22 miles (35 kilometers) up.
The latest pictures offer unprecedented views of a huge impact crater known for its bright salty deposits, and landslides are clearly visible on the rim.
The functioning instruments aboard the Voyager spacecraft still going strong.
Although technology on Earth has advanced dramatically since the Voyagers were launched, the two spacecraft are frozen, technologically speaking: They were sent on their missions with the best equipment available at the time (including an 8-track tape recorder for data storage, believe it or not) and they have stood the test of time. While time moves forward here on Earth, aboard the Voyager spacecraft it is always 1977.
Scientists from the Max Planck Institute for Astronomy (MPIA) in Heidelberg and the SPHERE instrument consortium at the Very Large Telescope of the European Southern Observatory (ESO) in Chile have discovered and characterised an extremely young exoplanet in a state of its formation.
— Sonia Bashir 🔥📸 (@SoniaBashir_) June 28, 2018
The 2018 Strawberry Moon was particularly exciting, as it arrived during Saturn’s annual “opposition”—the day Earth passes between the Sun and the ringed planet.
Thought to have formed some 4.51 billion years ago from debris left over after an impact between Earth and a Mars-sized body called Theia, the Moon is the second-brightest regularly visible celestial object—after the sun.
While the Moon itself does not radiate light, its dark surface reflects the sun’s rays at various times of day, making it a convenient timepiece; some of the earliest calendars were based on the Moon’s periods of waxing and waning.
Continue reading “2018 Strawberry Moon Pictures and Video”
On Saturn’s small moon Enceladus, perpetual fountains of alien seawater launch all sorts of curious stuff into space: water, salt, silica, and even simple carbon-containing compounds fly into the void—many of which are ingredients for life as we know it. | <urn:uuid:28cad27a-9d15-4d4d-b192-66cf9ae5c56f> | 2.84375 | 604 | Content Listing | Science & Tech. | 36.41114 | 95,484,137 |
Please see attached file for the properly formatted question. A reaction of a tertiary alkyl halide gives two products. Where do they come from (SN1, SN2, E1 or E2) processes? What are the mechanisms for these processes?
Which reaction is faster and what is the kinetics of these reactions? a) (CH3)3CCl ----> (CH3)3COH (in 70% water/methanol) b) (CH3)3CCl ----> (CH3)3COH (in 50% water/acetone) The faster reaction is shown and the kinetics are discussed.
Provide a reasonable synthetic pathway for the synthesis of 4-bromoacetanilide starting from benzene. Show the reagents necessary to accomplish each step and the structure of the intermediate products. Show only the reagents, not the mechanism. See attached file for full problem description.
2. Turn the -OH on carbon 5 around so it is close to the aldehyde carbon (carbon #1). 3. Form the hemi-acetal using the carbon #5 -OH and the carbonyl at carbon 1. a. As you make the hemi-acetal, write out the mechanism by which this occurs. Concentrate your efforts on what is happening at C5 and C1. Review the formation of
Please help with the following problem. For an SN2 reaction, the effect of solvent polarity is usually much less, but the ability (or really lack there of) of the solvent to solvate the nucleophile is the important criteria. Which of the two reactions proceed faster: a.) CH3CH2I in presence of ethanol or b.) CH3C
Could you please give a stepwise mechanism for the preparation of 3-nitrochalcone from 3-nitrobenzaldehyde and acetophenone. (This is an aldol condensation reaction)
Please find the mononitration product for the following (see attached file for diagrams). No mechanism is needed. (For part D the side chain should be COOC2H5 nots COOC2H2)
1. Suggest a method to prepare each of the attached compounds from alkyl halides (be specific on the alkyl halide used for each problem) 2. For each reaction suggested in #1, indicate whether it is SN2, SN1, E2, or E1.
Please indicate the arrow mechanism for the attached diagram of a chemical compound.
Please see attachment. I need help with providing reagents and conditions to complete the following transformations.
Complete the following multi-step synthesis. Enter your answers in the box provided. (please see attached file for full diagram)
Complete the following reactions. Show all the isomers possible. If no reaction occurs, indicate so. (See attached)
(See attached file for full problem description) Complete the attached synthetic scheme by providing the reagents required for synthesis
Write the mechanism for the attached transformation.
The question reads: the compound pentaerythritol C(CH2OH)4 used in making explosives, is obtained from the reaction of acetalaldehyde and formaldehyde in the presence of Ca(OH)2. Outline the probable steps in the structure. --- I think I know the final outcome I am having trouble with the steps to get to the final structure. Rea
With NMR spectral data supplied I need to know the structure of product X and structure of product Y as well as mechanism by which product X is formed. (See attached file for full problem description)
2. A. Draw structures for the following compounds: 1-phenyl-1,2-epoxybutane, dimethylsulfide B. Name the following compounds: see attached file for diagrams. 3. Imagine that you have treated cis-2,3-epoxy-3-methylpentane with aqueous acid in a ring-opening reaction. a. Draw the epoxide, showing stereochemistry. b.
What is the step by step mechanism for dehydration of 2-methylcyclohexanol so that the following products are obtained:3-methylcyclohexene (non-Zaitsev, E2), 1-methylcyclohexene (Zaitsev, E1), and methylenecyclohexene (hydride shift, minor product)? In addition, the 2-methylcyclohexanl exist in both cis and trans form. Pleas
Write structure of dibromine products that you think will be formed as a result of the reaction of Z-2-Pentene with Bromine. How about the dibromide products predicted when E-2-Pentene reacts with Bromine.
I need some help answering this question: Solvolysis reactions may be defined as reactions in which: a. Carbocations are required intermediates b. Elimination competes with substitution c. Reactivity is always accompanied by inversion of configuration d. The attacking nucleophile is usually the solvent e. Aprotic solvents
Please help with the following problem. Writing a chemical equation for the conversion of Codeine to Morphine in the body. I know that the ether group of codeine becomes an alcohol group in the morphine, but I am unable to get a formula with the other products. I could also use some help with making sure I have the funct
I need help with showing the products for the following attached reactions problem. Please see attachment. Show the product(s) of the following reactions. Show stereochemistry where applicable.
This was an experiment done in lab class. The the following alcohol was reacted with hydrochloric acid in presence of zinc chloride (HCl-ZnCl2) and the result:
This was an experiment done in lab class. The the following alcohol was reacted with hydrochloric acid in presence of zinc chloride (HCl-ZnCl2) and the result: 1. 1-butanol; test tube has no color change, clear liquid 2. 2-butanol; test tube had two layers formed, top lawer lookes white and oily 3. 2-methyl-2-propanol (tert-b
I need help writing the balanced equations for the attached problems and determining which reactions proceed by an SN1 mechanism and SN2 mechanism. --- 1. Write the balanced equations for the following: a. 2-bromobutane + NaI ---> b. 2-bromobutante + AgNO3 + EtOH ---> c. 2-bromo-2-methylpropane + NaI ---> d. 2-bromo-2-m
I need help with writing the reaction and predict the major product for the following reactions. (Make sure to consider stereochemistry and regiochemistry, if applicable) a) 1-butene-3-yne reacts with excess hydrogen in the presence of a Pd/C catalyst b) 1-Butyne reacts with BH3 followed by hydrogen peroxide.
Predict the two most likely products for the following reaction and show a stepwise mechanism for the formation of each product. (Hint: one product is formed by Markovnikov addition, the other by a carbocation rearragement.) (CH3)3CCH=CH2 + HCl ->
Beginning with acetylene and using any other reagents necessary, how would you synthesize 1,2-dichloropropane? (Hint: more than one step is required. Show all reagents and all intermediate steps clearly.)
Problem: Treatment of (2R, 3S)-2-bromo-3-phenylpentane with KOH can lead to different products, depending on the reaction pathway. Draw (2R, 3S)-2-bromo-3-phenylpentane and the major product(s) expected for each of the following reaction mechanisms: SN1, SN2. Please indicate the stereochemistry and regiochemistry clearly.
Bridged cyclic compounds like the ones shown in the attached .jpg are extremely unreactive in SN2 reactions. 1) Give a reason which will explain this. 2) How can you explain the fact that compounds of this type are also less reactive in the SN1 reaction than similar noncyclic compounds? (See attached file for full pro
Pure (R)-2-bromo-1-flourobutane reacts with sodium cyanide in aqueous ethanol to form pure (R)-2-flouromethylbutanenitrile. 1) What is the probable mechanism of this reaction? Explain your reasoning. 2) Based on your choice of mechanism, explain how both the substrate and the product can have R configuration? 3) Wha | <urn:uuid:14c020ff-7ae3-4316-b0e9-0eb4bb05bdd7> | 2.796875 | 1,834 | Q&A Forum | Science & Tech. | 52.736553 | 95,484,151 |
Where would we be without the effort of scientific experiments? Even the weird and scary ones produce fascinating results.
In order to blow your mind, scientists conducted the most out-of-this-world scientific experiments. Well, let’s just say, it was for the good of science, but as a side effect, these tests did seem a little strange, maybe a lot!
Elephants under the influence of LSD
On August 3, 1962, U.S. researchers, exploring their curiosity about what might happen to an elephant, by the name of “Tusko”, under the influence of LSD, proceeded to inject the substance into the animal’s body. The dose was certainly more than 3,000 times greater than what would be normally used by humans.
The result: the elephant screamed violently and died within an hour. Scientists just reported that the elephant was highly sensitive to LSD. But could it be that the drugs administered after the effect could be the real reason Tusko died?
Twenty years later, a similar experiment was conducted with two elephants and the same dosage. Instead of injecting the LSD, however, they chose to put it in the elephant’s water.
The results this time were much different. Aside from a few strange noises and sluggishness, the elephants were generally unaffected.
Resurrecting dead people
Sleeping with open eyes
In 1960, researcher Jan Oswald decided to explore whether sleep is possible with open eyes. After he gathered three brave volunteers, he put tape on their eyes to keep them open and then made them watch flashing lights and listen to loud music. Furthermore, electrodes connected to the legs of the volunteers aimed to cause severe pain.
The electroencephalography used in the experiment showed that all the three volunteers slept for 12 minutes!
Hypersexual male turkey
Two researchers at the University of Pennsylvania have discovered that male turkeys, when placed in a room with a model of a female turkey, tend to become excited and go into mating, just as they would if it was a real turkey. This conclusion came from several interesting scientific experiments, where elimination played an important role.
The scientists saw the results of these tests while gradually removing several pieces from the model of Turkey. First, the tail, feet, and wings, then on to the body itself. They also noticed that the male was positive in this whole process.
Even when the model had no body, the male turkey still responded sexually. Similar scientific experiments were conducted on White Leghorn Cocks.
In the 1940s, scientists conducted a chilling scientific experiment using dog heads. Severed heads of dogs were actually kept alive for several hours, mainly using artificial means of blood circulation. The heads responded alone, by moving their ears, responding to light and licking their mouths.
Again, in 2005, scientists conducted a similar experiment, this time with a pack of dogs. The first procedure included rapidly killing the dogs by replacing the blood with oxygen and sugar saline.
After death, the animal’s blood was replaced and they were administered an electric shock to wake them. Although some suffered damage, others were perfectly intact.
From elephants on drugs to over-stimulated turkeys, science never fails to astound us with its weirdness and even cruelty. But before you think you’ve seen and heard it all, just wait. I am sure there are many more strange and otherworldly scientific experiments on the horizon. Let’s just hope that they will be more humane than those on this list.
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- 6 Uncomfortable Self-Esteem Activities That Will Boost Your Confidence - May 21, 2018 | <urn:uuid:89818ab9-cd0b-4cad-acbb-b9870dda633b> | 3.125 | 837 | Listicle | Science & Tech. | 49.702623 | 95,484,174 |
+44 1803 865913
Series: Freshwater Biological Association Scientific Publications Volume: 38
By: Rosalind M Pontin
178 pages, 145 b/w line drawings
This key to British rotifera is intended to be used by those unfamiliar with their structure and habitats, and is based, as far as possible, on those morphological characters which are most easily observed. The main character which has formerly been used to separate most families is the structure of the jaws. As this character is not easy to observe in many rotifers, it is used as little as possible in the present key. There is no separate key to families; the key gives identification to genera and then to species, which are grouped in families. Most rotifers encountered are females, reproducing parthenogenetically for most of their season of occurrence. Characters given in the main keys and descriptions of species apply mostly to females, but notes on the males are included. A key to genera of males is given separately.
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Although we know the tool’s general purpose, it can sometimes be difficult to tell if a specific pair of precision tweezers belongs to a surgeon or a master jeweller. It is now easier to solve similar conundrums about a type of protein that allows cells to react to their environment, thanks to scientists at the European Molecular Biology Laboratory (EMBL). Published in Science Signaling, their work offers a valuable resource for other researchers.
Whether in your eye being hit by light, in your blood fighting off disease, or elsewhere throughout your body, cells have to react to changes in their environment. But first, a cell must ‘know’ the environment has changed. One of the ways in which that information is transmitted within the cell is through tags called phosphate ions, which are added to or removed from specific molecules depending on the exact message that has to be conveyed. The tools the cell uses to remove phosphate ions are proteins called phosphatases. But it’s not always obvious what molecules – or substrates – a particular phosphatase acts upon.
“One of the biggest challenges in phosphatase research is finding substrates, and this is what our work supports,” says Maja Köhn from EMBL in Heidelberg, Germany, who led the study. “We’ve made it easier to create hypotheses about the relationships between phosphatases and their substrates.”
Xun Li, a post-doctoral student shared by Köhn’s lab and those of Matthias Wilmanns at EMBL in Hamburg, Germany and Janet Thornton at EMBL-European Bioinformatics Institute (EMBL-EBI) in Hinxton, UK, compiled the most complete picture to date of all the phosphatases in human cells, and their substrates. The scientists also grouped phosphatases into families, based on their three-dimensional structure, which can influence what molecules a phosphatase can act upon.
This information allows researchers to easily identify a phosphatase’s known substrates, and suggest new substrates based on how similar it is to other phosphatases. The web-like overview of interactions could even help explain unforeseen side-effects of drugs designed to interfere with phosphatases or with their phosphate-adding counterparts, kinases. To enable others to make such connections, Köhn and colleagues have created a free online database, DEPOD.
“When people have unexpected results, this could be a place to find explanations,” says Thornton, head of EMBL-EBI. “DEPOD combines a wealth of information that can be explored in a variety of ways, to make it useful not just to phosphatase researchers but to the wider community.”
European Molecular Biology Laboratory | <urn:uuid:0eddce9d-cfe4-486f-bd41-b54d37ef488c> | 3.3125 | 575 | News Article | Science & Tech. | 31.193892 | 95,484,199 |
A new substance that degrades plastic could help address environmental pollution. (Source: Pixabay)
(RNN) – A new substance that "eats" plastic could take a major bite out of global pollution.
Research scientists have engineered an enzyme that digests common plastics, a discovery that came about by accident.
The scientists unintentionally engineered the enzyme while studying PETase, a recently discovered natural enzyme that digests a type of plastic called polyethylene terephthalate, which can exist in the environment for centuries.
Researchers think the enzyme evolved in a Japanese waste recycling center.
As they studied the structure of the natural enzyme, the scientists realized they’d accidentally engineered a new enzyme that was even better at breaking down plastic than the one they’d been studying.
"Serendipity often plays a significant role in fundamental scientific research and our discovery here is no exception," said Professor John McGeehan of the University of Portsmouth, which conducted the research, along with the U.S. Department of Energy’s National Renewable Energy Laboratory.
Now the researchers are trying to improve the new enzyme so they can put it to work eating up all the plastic out there.
The teams’ findings were first published in the journal “Proceedings of the National Academy of Sciences of the United States of America.”
Copyright 2018 Raycom News Network. All rights reserved. | <urn:uuid:50930173-f4de-4052-be1b-5a10f4240e2c> | 3.1875 | 291 | News Article | Science & Tech. | 28.262181 | 95,484,211 |
To investigate blue crab movements in the Gulf of Mexico, we will be tagging and releasing 31,000 crabs throughout the bays, estuaries, and offshore waters of the Gulf. Our tags are orange 1″ x 2″ plastic rectangles wired around the crab’s spines. This tagging project will allow us to track the movements of spawning females and better understand the biology and movements of this valuable species. You can contribute to the success of this project by clicking below to report any tagged crabs you catch. There is a $5 or $50 reward for each reported tag.
January 10, 2018: After a busy fall tagging season, we’re now up to 13,500 crabs tagged across the Gulf of Mexico.
June 28, 2017: We’ve now tagged over 10,000 crabs and have received reports of over 2,000 recaptures. Keep watching for tagged crabs, and please call us if you catch one!
April 20, 2017: We’ve now tagged over 8,000 crabs! Crabs have been tagged as far southwest as Lower Laguna Madre, TX and as far east as Steinhatchee, FL.
January 30, 2017: We’ve now moved from our www.nicholls.edu/blue-crabs site to blue crab.usm.edu. Although tagging has slowed for the winter, we’ve now tagged over 6,000 crabs and expect things to pick up again soon!
October 31, 2016: After a busy summer and the first few weeks of fall, we’ve now tagged over 5,000 crabs! Also, we have moved from Nicholls State University to the Gulf Coast Research Lab, University of Southern Mississippi. Expect website modifications in the coming weeks as we move to USM servers.
Frequently Asked Questions:
Q: Where are crabs being tagged?
A: We are tagging crabs throughout all five Gulf Coast states, both within the estuaries and offshore.
Q: Who is doing the tagging?
A: The project is being led by Dr. Zack Darnell’s lab at the University of Southern Mississippi, based at the Gulf Coast Research Lab, but we are working closely with commercial crabbers and state management agencies across the Gulf. For more information on our other research, please visit http://sites.usm.edu/zdarnell.
Q: Won’t the crabs lose the tags when they molt?
A: We are only tagging mature female blue crabs. Female blue crabs molt many times through their life, but once mature they stop molting. By only tagging mature females, we are ensuring that we are only tagging crabs that will not molt.
Q: How do I know if a tag is worth $5 or $50?
A: The front of each tag lists the reward amount for that particular tag.
Q: What information do I need to report if I catch a tagged crab?
A: Please record the tag number (B04738 on the crab shown above), the date you caught it, the location where it was caught (GPS if possible, or a descriptive location with the nearest landmark), and whether or not the crab was carrying eggs (also called a sponge). If it is carrying eggs, please record whether the eggs were orange, brown, or black. This information tells us the developmental stage of the eggs.
Q: What should I do with the crab after I report it?
A: Once you report the information, you can either (1) remove the tag and harvest the crab as you usually would, (2) release the crab with the tag still attached at the same location where you caught it, or (3) freeze the crab with the tag still attached for return to us. If you want to return the frozen crab to us, please let us know when you report the tag and we can arrange for someone to pick up the frozen crab from you.
Are you interested in helping us tag crabs?
Are you interested in getting involved and helping us tag crabs? We are looking for additional commercial crabbers across the Gulf coast willing to help us tag. Please contact Zack Darnell at firstname.lastname@example.org if you are interested.
Funding for blue crab tagging research was provided by the National Oceanic and Atmospheric Administration and Louisiana Sea Grant. | <urn:uuid:c56032a8-e7f3-4e5a-92be-5f616e043d37> | 2.53125 | 905 | About (Org.) | Science & Tech. | 68.915569 | 95,484,225 |
Last update: 09:44 | 10/01/2018
Antarctica may be thousands of kilometres from the central Pacific but events there can have a significant effect on the White Continent's ice.
The Getz Ice Shelf in West Antarctica feels the linkage strongly -- Photo: NASA
Scientists have shown how ice shelves - the floating fronts of marine-terminating glaciers - respond to the El Niño phenomenon.
The warming of tropical eastern Pacific seawaters will lead to a change in wind patterns in the polar south.
This promotes snowfall on the shelves, and also melting of their undersides.
These are competing processes, of course. One adds mass; one takes it away.
However, the net outcome is a loss, say scientists. The reason? The ice removed from underneath the floating slabs has a higher density than the fluffy new snow at the surface.
It is another example of the complexity researchers need to grasp as they try to gauge how Antarctica will react to a warming world.
Although much of the continent is relatively static in its behaviour at the moment, it is losing ice in the west, especially in the Amundsen Sea sector, where glaciers are thinning and accelerating.
The ice being shed in this region - many tens of billions of tonnes a year - adds to global sea-level rise.
Dr Fernando Paolo, from the Scripps Institution of Oceanography, and colleagues report their work in the journal Nature Geoscience.
They analysed more than two decades of satellite radar measurements of ice shelves. The spacecraft have continuously tracked the height of the shelves since 1994.
Once the scientists had removed the long-term negative trend, they found a variable signal that could be tied to the El Niño/Southern Oscillation (ENSO).
This oscillation famously sees surface waters in the eastern tropical Pacific seesaw between warmer than average conditions (El Niño) and cooler than average phases (La Niña).
ENSO is recognised to have global influence, altering patterns of rainfall and drought, for example. And in the southern polar region, it appears to influence atmospheric pressure fields.
One in particular, referred to as the Amundsen Sea Low, governs both regional winds and ocean circulation.
During an El Niño, this fosters higher snowfall rates on shelves, but it also pulls more warm water up from the deep which can get under the shelves and melt them.
The combined effect leads to a loss in mass of the shelves. In a big El Niño phase, like the one in 1997/98, this reduction can be equivalent in scale to that stemming from the ongoing, long-term negative thinning trend.
"That means for a short period of time you are adding the two together. And that's key information to put into computer models if you want to properly represent the dynamics of these systems," explained Dr Paolo, who has now moved to the US space agency.
In La Niña years, the reverse happens: less snowfall, but also less melting on the shelves' undersides. This works briefly to slow the ongoing, long-term negative trend.
"Before this we knew that ENSO should affect Antarctica - that it should affect the ocean and the atmosphere around the continent. But this is the first time we've detected that signal on the ice shelves themselves," said Scripps co-author Prof Helen Fricker.
The study shows the value of ongoing satellite measurements in polar regions. Because there can be several years between El Niño events, a single satellite may catch only a couple of occurrences during its operational life.
An unbroken series of satellites is therefore required to capture the big picture.
The European Space Agency (Esa) has managed to do this with its radar satellites ERS-1, ERS-2, Envisat and Cryosat - although that may not be the case for much longer as Cryosat is ageing and any replacement is unlikely to be available until the mid-2020s.
Nasa has not done as well as Esa. It has a allowed a gap to develop between its satellite laser missions, which make very similar observations to radar over the Antarctic and the Arctic.
A major Earth observation report called the "Decadal Survey" was delivered last week through the US National Academies of Sciences, Engineering, and Medicine
The authors said it was "critical" that a satellite capability was maintained to measure ice elevation in the polar regions by either Europe or America. | <urn:uuid:d9414b07-d922-42d9-a1d1-ac9b1f5a656c> | 3.8125 | 915 | Truncated | Science & Tech. | 41.924159 | 95,484,234 |
Physicists using the SOLEIL synchrotron in France are the closest yet to realizing a thought experiment first proposed in 1927 by Albert Einstein. A variation on the much-loved double-slit experiment, the measurement confirms an aspect of quantum theory that Einstein had sought to discredit. The SOLEIL experiment uses two excited atoms in place of the two slits of Einstein’s experiment and shows that when one can determine which atom has emitted an electron, a quantum interference pattern vanishes.
Einstein made several attempts to refute the inherent uncertainty of quantum mechanics by proposing thought experiments, which could not be performed in the lab at the time. One involved the principle of wave–particle duality, which predicts that a succession of single particles passing through two slits will build up a wave-like diffraction pattern on a screen. This occurs because the wave-like property of each particle allows it to travel through both slits at once. Einstein pointed out that an extremely sensitive sensor could detect the recoil of the individual slit that each electron passed through, while not disturbing the diffraction pattern. This flew in the face of quantum mechanics, and Einstein’s great rival, Niels Bohr, countered by arguing that the diffraction pattern would simply not occur if the experimenter knew which slit each electron had passed through.
While this was a pure thought experiment at the time, its combination of conceptual simplicity and formidable experimental difficulty has provided an irresistible challenge for modern-day experimentalists. In 2001 Serge Haroche and colleagues at the Ecole Normale Supéérieure in Paris demonstrated the principle in an analogue system, using a microwave pulse to split the internal state of a small number of Rydberg atoms into two separate states that evolved at different rates before being recombined. Then in 2011 Jörg Schmiedmayer and colleagues at the Vienna University of Technology achieved a closer approximation.
Now, Catalin Miron and colleagues at SOLEIL, together with collaborators in Sweden, Japan and Romania, are the closest yet to recreating the original thought experiment in the lab. They use a diatomic oxygen molecule that is excited by tunable X-ray synchrotron radiation on the PLÉIADES beamline. By adjusting the X-ray energy, the researchers can promote an electron from an inner molecular orbital into either a high-energy bound state or a repulsive state in which the molecule breaks apart. After this transition, one of the atoms emits another electron called an Auger electron, recoiling as it does so.
If the first electron has been promoted to the bound state, it relaxes back to the molecular ground state and the two atoms recoil together when the Auger electron is emitted. This means that measuring the recoil of the atoms reveals nothing about which atom emitted the electron. However, if the electron has been promoted to the repulsive state, the molecule breaks apart to create separate oxygen atoms. If the Auger electron is emitted after the molecule breaks apart, the atoms will not recoil together, and measuring the recoil of the atoms will reveal which atom ejected the electron. The two atoms therefore act as the slits of the thought experiment, and the emission of an electron is analogous to a particle emerging from the two slits. If the atoms recoil together, we do not know through which slit the electron passed – but if only one recoils, we do know which slit was used.
In place of the screen, the team used an extremely elaborate, self-built and unique machine called EPICEA, which measures all three components of the momenta of both the emitted electron and the recoiling atom left behind. “This is actually what I built for my PhD thesis 20 years ago,” says Miron.
Einstein wrong again
By correlating the emitted electron energy to the angle between the electron emission and the axis of the diatomic molecule for a large number of photon–molecule collisions, the researchers electronically reconstructed the “interference pattern”. By looking at the Doppler shift of the recoiling ion, the researchers could also calculate whether one or both atoms had recoiled. When the two atoms were indistinguishable, interference fringes were produced (see figure); whereas when the emission bore a clear signature of having come from one atom or the other, a continuous band was produced with no evidence of fringes. This is in good agreement with high-level theoretical calculations – and shows once again that Bohr’s interpretation of the thought experiment is the correct one.
Jörg Schmiedmayer calls the work “a nice demonstration of a very fundamental effect”, and explains that while, in principle, “the physics is exactly the same in Haroche’s experiment or in our experiment…in these other papers up till now the slit was a photon or something like that. Here you have two matter particles that are your two slits. These are steps that are getting closer and closer to the original proposal of Einstein and Bohr.”
The research is described in Nature Photonics.
- In 2002 Physics World readers voted the double-slit experiment with electrons “The most beautiful experiment” | <urn:uuid:64cb6266-9757-4162-9f0e-7f34d7d47780> | 3.734375 | 1,070 | News Article | Science & Tech. | 26.935323 | 95,484,251 |
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.
Sun spewed a two million mile per hour stream of charged particles toward the invisible
magnetic fields surrounding Earth, known as the magnetosphere on April 5, 2010. As the particles interacted with the magnetic fields, the incoming stream of energy caused stormy conditions near Earth. Some scientists believe that it was this solar storm that interfered with commands to a communications satellite, Galaxy-15, which subsequently foundered and drifted, taking almost a year to return to its station. So to better understand how to protect satellites from intense bursts of energy from the sun, scientists study the full chain of space weather events from first eruptions on the sun to how the magnetic fields around Earth compress and change shape in response. During the April 5 storm, two NASA Heliophysics System Observatory missions, the Interstellar Boundary Explorer (IBEX) and two spacecraft called the Two Wide-Angle Imaging Neutral-Atom Spectrometers (TWINS), were perfectly positioned to view the storm from complementary viewpoints. The three sets of instruments have been used together to paint a more complete picture of what happens during a solar storm, from initial impact of solar energy through to the particles that ultimately slide down into Earth’s atmosphere near the poles. The two TWINS spacecraft and IBEX orbit Earth in very different paths. TWINS travels along a highly elliptical orbit around Earth through the magnetosphere. IBEX, too, circles Earth, but generally lies outside the magnetosphere allowing it to map the very edges of the solar system. Together, they offer glimpses from the inside and outside of the magnetosphere, including the side that faces the sun, the side that extends long away from the sun ,the magnetotail, and an electric current that sometimes appears around Earth like a giant hula hoop called the ring current. The ENA images from IBEX were taken from a distance of around 180,000 miles above the magnetosphere. They show that the magnetosphere immediately compressed under the impact of the charged particles from the solar wind. Minutes later, one of the TWINS spacecraft observed changes in the inner magnetosphere from a much-closer 28,000 miles: the ring current began to trap incoming charged particles. About 15 minutes after impact, these trapped particles gyrated down magnetic field lines into Earth’s atmosphere, a process known as “precipitation.” The time delay between the onset of trapped particles and losing them to the atmosphere points to a fairly slow set of internal processes carrying the region from storm impact through compression to precipitation. | <urn:uuid:60a363a8-a012-4699-825b-33ffe9950927> | 2.96875 | 585 | News Article | Science & Tech. | 31.211655 | 95,484,272 |
NASA: September 2017 starts with flares3:05
NASA’s Solar Dynamics Observatory, which watches the sun constantly, captured images of the events. Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however — when intense enough — they can disturb the atmosphere in the layer where GPS and communications signals travel. Courtesy: NASA
OUR Sun has sent forth seven flares in seven days. One is headed our way.
One, unleashed last week, was the solar equivalent of Hurricane Irma — a monster X9.3 storm. Even though it only struck Earth a glancing blow, this was enough to disrupt some radio communications.
Since then, the same cauldron of magnetic activity on the Sun’s surface has erupted with flare after flare.
Another big one, at magnitude X8.2, was blasted outwards overnight. It’s arriving soon.
SPACE WEATHER WARNING
What makes these flares so significant is that the explosions have been strong enough to tear pieces of the Sun away from itself, and fling it into space. It’s called a coronal mass ejection (CME), and — depending on its strength — if one was to hit Earth the effects could range from an annoyance to catastrophic.
The latest warning from the Space Weather Prediction Center is that the latest flare could cause a moderate disruption radio communications over North and South America for up to an hour tonight.
While the Earth’s atmosphere protects those of us on the surface from the most harmful rays, things get different the higher up you go.
Fortunately, the odds are very low things will get any worse. The Solar System is an enormous shooting gallery — with comparatively tiny targets. Even when the Sun is fully awake in its 11-year cycle of eruptions and silence, Earth generally only gets the annoyance of satellites being disrupted in orbit — along with the beauty of glowing aurorae high in our skies.
The Sun is supposed to be approaching solar minimum — a period where hardly a ripple marks its surface.
But observations over the centuries have shown that when a solar ‘hot spot’ does emerge at this time, it tends to be very hot. It’s times like these that have produced some of the biggest solar flares recorded.
“The X9.3 flare was the largest flare so far in the current solar cycle, the approximately 11-year-cycle during which the sun’s activity waxes and wanes,” a NASA statement reads.
“The current solar cycle began in December 2008, and is now decreasing in intensity and heading toward solar minimum. This is a phase when such eruptions on the sun are increasingly rare, but history has shown that they can nonetheless be intense.”
Why this happens, however, is not yet known.
The first impact from a solar flare comes from charged particles travelling at 150,000,000km/h. These arrive at Earth about an hour after an eruption. But the bulk of the material spewed forth by a CME can take a couple of days to reach our planet — giving us time to prepare.
Solar flares can be a serious threat. The biggest blobs of energy — if they were to strike Earth full-on — charge the ionosphere, causing it to absorb radio waves. This could cut communications with everything from airliners to satellites — including GPS signals.
Radiation levels in space would also spike, posing a health risk to astronauts aboard the International Space Station and even airline passengers.
The most severe geomagnetic storms could pump unwanted electrical current into powerlines, and even electrical devices. These have been known to fry electrical networks, blacking out entire cities and states.
In 1989, the entire Canadian state of Quebec was blacked out for nine hours after a direct hit from a coronal mass ejection. Another 200 power grids in the United States experienced surges. The worst was in 1859, when electricity was only beginning to be used in telegraph wires. These failed worldwide.
A similar hit, now, could be an electronics apocalypse — taking out power networks and destroying electronic systems such as banking transactions. It would be a worldwide disaster, with transportation and food production networks crippled.
The current solar hotspot, dubbed Active Region 2673, was first spotted on August 29. This flare is likely to be the last to have any impact on Earth as the region is rotating towards the Sun’s far side. | <urn:uuid:62d2edf2-4c9c-45e9-a9f6-1c24f56b67c6> | 4 | 927 | News Article | Science & Tech. | 48.749454 | 95,484,277 |
Transplanting a Genome
Researchers have taken a big step toward creating synthetic genomes.
Forget kidneys and hearts: genomics pioneer J. Craig Venter has spearheaded a much tinier transplantation procedure. Scientists at the J. Craig Venter Institute, in Maryland, have transferred an entire genome from one bacterium to another. They say the findings, which are described today in the journal Science, mark a significant advance toward the goal of creating synthetic genomes. Venter and his colleagues ultimately aim to build genomes from scratch and transplant them into bacterial cells in order to create custom-made, fuel-producing microorganisms.
“This paper is a landmark in biological engineering,” said Barbara Jasny, Science’s deputy editor, at a press conference on Wednesday. “It takes us from the ability to move one gene or a set of genes to the ability to move an intact genome.”
Scientists started with two species of mycoplasma, a type of bacteria that lack cell walls and have very small genomes. They then isolated the DNA of one species, which had been given an additional gene to make it resistant to an antibiotic, and transplanted it through the cell membrane of the second species. As the host bacteria grew and divided in the presence of this antibiotic, cells carrying the original chromosomes disappeared, leaving only cells containing the transplanted chromosome. Most important, the host bacterium took on the molecular characteristics of the donor. “The entire protein repertoire changes,” Venter said at the press conference.
For Venter’s team, the genome transplant is a step toward engineering microbial machines to efficiently produce fuel. The researchers are currently trying to stitch together a synthetic version of the genome of Mycoplasma genitalium, a bacterium found in the human genital tract, which Venter’s group has been studying for more than a decade. By rearranging or deleting specific chunks of the synthetic genome and inserting it into a bacterial host, scientists should be able to figure out which genes are critical for the organism to function–in essence, the minimal genome. This minimal genome could then be modified to carry fuel-producing genes, and the entire string of DNA could be transplanted into a bacterial carrier.
In addition to the research at his institute, Venter has also founded a Maryland-based startup called Synthetic Genomics. (See “Building a Bug to Harvest Oil.”) The company, which is working with BP, hopes to commercialize bacteria for energy applications.
But some scientists question whether a minimal genome is necessary to engineer useful bacteria. “It’s not clear why a minimal cell or a cell engineered by whole genome transplantation would be more cost-effective than just inserting or changing a few genes in a more robust genome,” says George Church, a geneticist at Harvard Medical School, in Boston. He points out that synthesizing even the smallest genome would cost an estimated $10 million with today’s technology. In fact, other companies are tinkering with existing microbes to engineer biological fuel factories. (See “A Better Biofuel.”)
However, Venter said that his approach would eliminate inherent biological traits that make extensive biological engineering tricky. For example, a nonessential metabolic process could suck away a molecular precursor needed for fuel production. In addition, said Venter, “existing organisms have a rapid ability to evolve. In synthetic biology, you don’t want a system that will self-evolve into something else. We want to eliminate those elements from the cell from the beginning.”
The genomic transfer technique is similar to nuclear transfer–used to clone Dolly the sheep–in which the nucleus of an adult cell is transferred into an egg. But getting the process to work in bacteria has been trickier. Scientists speculate that nuclear proteins transferred along with the DNA during nuclear transfer may help the process. Bacteria do not have a nucleus, and in this experiment, only DNA was transferred into the host cell. Researchers did this on purpose to show that only DNA was needed to successfully reprogram the host bacterium–a property that will be necessary when scientists are ready to transplant entirely synthetic genomes.
Scientists don’t fully understand how the genome transfer worked, particularly how the host genome disappeared. And it’s not yet clear how well the technique will work in other bacteria or in more-complex organisms. Most bacteria have a defense mechanism that chops up any foreign DNA that enters the cell, so scientists would need to find a way to block the DNA-degrading enzymes in each different species before they could successfully transplant foreign genomes into them.
Couldn't make it to EmTech Next to meet experts in AI, Robotics and the Economy?Go behind the scenes and check out our video | <urn:uuid:48134b05-5866-4d1a-8bff-e184c9478d11> | 3.265625 | 984 | News Article | Science & Tech. | 34.77666 | 95,484,280 |
Lateral transport of suspended particulate matter in nepheloid layers along the Irish continental margin - a case study of the Whittard Canyon, North-East Atlantic Ocean
Wilson, Annette M.
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Nepheloid layers, defined by their increased concentration of suspended particulate material (SPM), are an important transport mechanism in the pelagic to benthic coupling of material, including rich organic matter. Fortuitously located at the edge of the Celtic Sea shelf along the NE Atlantic margin; an area of high energy and primary production–the Whittard Canyon is recognised as a refuge for benthic and suspension feeding fauna. The formation and composition of material in benthic (BNL) and intermediate nepheloid layers (INLs) in the Whittard Canyon were investigated over the course of three research surveys between 2011 and 2013, in order to investigate the extent and significance of this transport pathway. BNLs were detected in the four surveyed branches, to water depths greater than 2500 m, with INLs occurring as extensions from the benthic source and stretching distances of 25 km off the slope. Hotspots for nepheloid layer generation were identified at depths of critical and supercritical conditions for semidiurnal internal tide reflection and at the boundaries of the permanent thermocline and Mediterranean Outflow Water. Seasonal variations in primary productivity and, temporal variations induced by the combined effects of (seasonal) stratification and storm activity, influenced nepheloid layer generation and the distribution patterns of SPM. Recently, bottom trawling activity has also become a recognised and legitimate mechanism for sediment transport, feeding thick or enhanced nepheloid layers (ENLs). ENLs, with concentrations of SPM typically an order of magnitude higher than normal nepheloid layers, were detected during the survey in June 2013. High spatial and temporal coverage of bottom trawlers, identified using Vessel Monitoring System data, coincided with the occurrence of these events. Material collected from (normal) BNLs and INLs in 2013 showed enrichment of fresh particulate organic material (molar C/N, pigments, SEMs, lipid biomarkers). BNLs in the upper reaches of the canyon (650 – 750 m) had high concentrations of labile lipids and showed high contributions of chlorophyll a and other compounds derived from primary production in the surface waters. Considerable compositional heterogeneity was also observed in the nepheloid layers, indicative of the inherent natural, spatial and temporal variance of settling organic and resuspended material that is influenced by different processes in the different branches. Localised variations in energy fluxes in the different canyon branches partly explain the frequency, location and level of turbidity of the nepheloid layers. However the differing degree of trawling activity adjacent to the canyon branches is also likely to have an influence, particularly on the compositional components. Qualitative analysis (lipid biomarkers) from benthic nepheloid layers (1300 – 1400 m) showed an apparent eastern and western differentiation which is likely associated with the alteration of material by trawling activity. In terms of sediment transport rates, the magnitude of the fishing activity adjacent to the Whittard Canyon is shown to have impacts on human rather than geological timescales. Furthermore, a unique assemblage of limid bivalves and deep-sea oysters was found in association with nepheloid layers in the canyon. Changes to the distribution and delivery of rich organic matter by nepheloid layers are likely to affect faunal feeding, distribution patterns and, the functioning of these canyon ecosystems.
This item is available under the Attribution-NonCommercial-NoDerivs 3.0 Ireland. No item may be reproduced for commercial purposes. Please refer to the publisher's URL where this is made available, or to notes contained in the item itself. Other terms may apply.
The following license files are associated with this item: | <urn:uuid:656759a5-8a23-4db8-917c-0f12b183b2e0> | 2.671875 | 823 | Truncated | Science & Tech. | 15.448308 | 95,484,309 |
Selective analysis of radionuclides by the delayed coincidence method
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The cascade process of decay of most radionuclides with corpuscular and photon radiation (β-α, α-ψ, β-ψ, ψ-ψ, α-x, β-x) with an average life-time of the intermediate states from 10−10 to some 10 sec, makes it possible to use the delayed coincidence method for selective analysis. Natural mixtures of radionuclides were analyzed for isotopes214Bi(RaC),212Bi(ThC),219Rn(An) and220Rn(TN)with the aid of instruments including scintillation detectors and a multichannel time selector by using β-α and α-α delayed coincidences, while isotopic ratio235U/235U in natural uranium was determined by using α-ψ coincidences. The instrument background did not exceed 1 pulse per hour per coincidence channel. Subjected to analysis were rocks with Clarks of radioactive elements.
KeywordsUranium Radon Thorium Decay Product Thoron
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The Large Hadron Collider, otherwise known as the LHC, is designed to hurl protons and nuclei of atoms together a phenomenally high speeds extremely close to the speed of light.
The LHC has 2 beams going in opposite directions around an oval of about 27 kilometres, at specified pints, where experiments like ATLAS and CMS are located, they cross and collisions may occur.
These collisions are at an energy high enough that particles are created from the interaction of the colliding protons and neutrons. Most of the particles detected from these collisions are known, but physicists are still interested in how they behave at the energies achieved in the LHC, but the most sought after prize is the Higgs Boson - along with possibility of finding other particles predicted, but not yet observed.
Theoretical nuclear physicists can not account for why the sub atomic particles, that we have already detected so far, have mass. So Peter Higgs, along with others, postulated a totally new type of particle, now called the Higgs Boson, that appears to neatly resolve the problem.
Some other physicists, think that the Higgs Boson does not exist, and there must be some other mechanism to account for mass. However, most physicists feel that searching for the Higgs is worthwhile, as it is important to find evidence of it either definitely existing or not existing, as the case may be. The existence of the Higgs would confirm our understanding of the so called standard model of nuclear particles and allow our understanding of it to be extended to higher energies, or force physicists to reconsider the standard model in a very fundamental way.
Also of considerable interest: would be new types of particles not predicted, and new ways of matter behaving at the super high temperatures found in the collisions of nuclear particles at the LHC.
The LHC had been designed to run at 10 TeV (10,000,000,000,000 electron volts, as distinct from the maximum energy possible in the average New Zealand home of 240 volts), but due to technical problems they will run at 7 TeV. The LHC will be run at this energy for 18 to 24 months to get a decent amount of physics done and to get more experience of operating the system, plus it gives more time to prepare what is required to operate at the design energy of 10 TeV.
Note that the LHC is run at about 270 degrees Celsius below the freezing point of water, or less than 2 degrees above absolute zero. So another reason for the long period at just one energy level of 7 TeV, is that while there are improvements they can make to increase the energy in stages to 10 TeV, is that simply warming the LHC up to room temperature and cooling it down again takes at least 2 months, in addition to the time required to make the actual engineering modifications and subsequent testing.
It is expected that the LHC will restart operations in the few days about the level it finished last year of about 1 TeV and ramp up over a few week to 7 TeV. They want to avoid any mishaps that might put the LHC out of commission, like what happened shortly after they started up the first time when they had an explosion that forced a delay of a year while they fixed the problem.
Physicists from all around the world are hard at work preparing to do some exciting new physics at the LHC, including some people from New Zealand.
Rorting In The Auckland Property Market !
3 years ago | <urn:uuid:93818674-6b6d-4ae5-862b-a98040114e31> | 3.609375 | 714 | Personal Blog | Science & Tech. | 38.592667 | 95,484,359 |
Chemi-ionization is the formation of an ion through the reaction of a gas phase atom or molecule with an atom or molecule in an excited state while also creating new bonds. This process is helpful in mass spectrometry because it creates unique bands that can be used to identify molecules. This process is extremely common in nature as it is considered the primary initial reaction in flames.
The term chemi-ionization was coined by Hartwell F. Calcote in 1948 in the Third Symposium on Combustion and Flame, and Explosion Phenomena. The Symposium performed much of the early investigation into this phenomenon in the 1950s. The majority of the research on this topic was performed in the 1960s and '70s. It is currently seen in many different ionization techniques used for mass spectrometry.
Chemi-ionization can be represented by
where G is the excited state species (indicated by the super-scripted asterisk), and M is the species that is ionized by the loss of an electron to form the radical cation (indicated by the super-scripted "plus-dot").
The most common example of A-type chemi-ionization occurs in hydrocarbon flame. The reaction can be represented as
This reaction is present in any hydrocarbon flame and can account for deviation in the amount of expected ions from thermodynamic equilibrium. This can then lead to B-type chemi-ionization which can be represented as
As well as
Where M* represents an excited state metal. This reaction illustrates the light generated by the chemi-ionization reaction resulting in the light we know from flames.
Chemi-ionization has been postulated to occur in the hydrogen rich atmospheres surrounding stars. This type of reaction would lead to many more excited hydrogen atoms than some models account for. This affects our ability to determine the proper optical qualities of solar atmospheres with modeling.
- IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "chemi-ionization". C01044
- Klucharev, A. N. (1993), "Chemi-ionization processes", Physics-Uspekhi, 36 (6): 486, Bibcode:1993PhyU...36..486K, doi:10.1070/PU1993v036n06ABEH002162
- Dyke, John M.; Shaw, Andrew M.; Wright, Timothy G. (1994). "Study of Chemiionization Reactions in the O + 2-Butyne Reaction Mixture". The Journal of Physical Chemistry. 98 (25): 6327–6331. doi:10.1021/j100076a016. ISSN 0022-3654.
- Calcote, Hartwell F. (1948). "Electrical properties of flames". Symposium on Combustion and Flame, and Explosion Phenomena. 3 (1): 245–253. doi:10.1016/S1062-2896(49)80033-X. ISSN 1062-2896.
- Chen, Lee Chuin; Yu, Zhan; Hiraoka, Kenzo (2010). "Vapor phase detection of hydrogen peroxide with ambient sampling chemi/chemical ionization mass spectrometry". Analytical Methods. 2 (7): 897. doi:10.1039/c0ay00170h. ISSN 1759-9660.
- Mason, Rod S.; Williams, Dylan R.; Mortimer, Ifor P.; Mitchell, David J.; Newman, Karla (2004). "Ion formation at the boundary between a fast flow glow discharge ion source and a quadrupole mass spectrometer". Journal of Analytical Atomic Spectrometry. 19 (9): 1177. doi:10.1039/b400563p. ISSN 0267-9477.
- Vinckier, C.; Gardner, Michael P.; Bayes, Kyle D. (1977). "A study of chemi-ionization in the reaction of oxygen atoms with acetylene". The Journal of Physical Chemistry. 81 (23): 2137–2143. doi:10.1021/j100538a001. ISSN 0022-3654.
- Fontijn, A.; Miller, W.J.; Hogan, J.M. (1965). "Chemi-ionization and chemiluminescence in the reaction of atomic oxygen with C2H2, C2D2, and C2H4". Symposium (International) on Combustion. 10 (1): 545–560. doi:10.1016/S0082-0784(65)80201-6. ISSN 0082-0784.
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- Mihajlov, Anatolij A.; Ignjatović, Ljubinko M.; Srećković, Vladimir A.; Dimitrijević, Milan S. (2011). "CHEMI-IONIZATION IN SOLAR PHOTOSPHERE: INFLUENCE ON THE HYDROGEN ATOM EXCITED STATES POPULATION". The Astrophysical Journal Supplement Series. 193 (1): 2. arXiv: . Bibcode:2011ApJS..193....2M. doi:10.1088/0067-0049/193/1/2. ISSN 0067-0049. | <urn:uuid:8f426d09-7768-421b-b43b-fa5c3231c4dc> | 3.34375 | 1,226 | Knowledge Article | Science & Tech. | 70.619923 | 95,484,404 |
The Purbeck Marine Wildlife Reserve lies within the boundary of the Dorset and East Devon World Heritage Site on the south coast. This study investigated the influence of visitors on intertidal biodiversity at Kimmeridge Bay, the only accessible part of the reserve. The assemblages present on two rock ledges were compared: Washing Ledge, which is regularly visited and utilized by people, and Yellow Ledge, which is more isolated and visited much less regularly. At each ledge, three habitat types were investigated: open rock, rockpools and the fucoid zone. Multivariate statistical analysis revealed significant differences in assemblages between ledges and among habitat types. The differences observed in the communities of the two ledges can be explained to some extent by natural ecological processes, but human impacts were also detected. The most obvious contrast associated with trampling was a reduction in the larger, branching species of algae and an increase in ephemeral and crustose species in the more heavily utilized areas.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:3df85939-7000-4f13-93ee-67dd6511b2e7> | 3.140625 | 221 | Academic Writing | Science & Tech. | 10.326286 | 95,484,471 |
- Open Access
Selection and gene duplication: a view from the genome
© BioMed Central Ltd 2002
Published: 15 April 2002
Immediately after a gene duplication event, the duplicate genes have redundant functions. Is natural selection therefore completely relaxed after duplication? Does one gene evolve more rapidly than the other? Several recent genome-wide studies have suggested that duplicate genes are always under purifying selection and do not always evolve at the same rate.
When a gene duplication event occurs, the duplicate genes have redundant functions. Many deleterious mutations may then be harmless, because even if one gene suffers a mutation, the redundant gene copy can provide a back-up function. Put differently, after gene duplication - which can arise through polyploidization (whole-genome duplication), non-homologous recombination, or through the action of retrotransposons - one or both duplicates should experience relaxed selective constraints that result in elevated rates of evolution. This hypothesis originated as least as early as Ohno's seminal book , which emphasized the importance of gene duplications in organismal evolution. But for decades any test of the hypothesis had to rely on small numbers of gene duplicates; doubts thus remained over whether conclusions derived from such case studies were representative of all genes in a genome. This changed with the availability of complete genome sequences from multiple organisms. Such sequence information can address not only this question but also many others related to the influence of selection on gene families. For instance, does one duplicate evolve faster and thus acquire new functions more rapidly than the other? How frequent are beneficial mutations that generate new and advantageous functions? And how frequent is gene conversion of duplicate genes, in which recombination and DNA repair between very similar genes convert the sequence of one to that of the other?
Purifying or completely relaxed selection?
Two recent studies [3,4] analyzed these ratios in multiple fully sequenced and several partially sequenced genomes. The results are unequivocal: the vast majority of duplicate genes experience purifying selection. Even very closely related gene duplicates, no older than a few million years, experience selective constraints - the ratio Ka/Ks is smaller than one even in these cases. Recent duplicates appear to tolerate more replacement amino-acid substitutions than older duplicates, however. For duplicates that differ at less than 5% of synonymous sites, between one in two and one in three substitutions are amino-acid replacement substitutions. For old duplicates, this number falls to between one in ten and one in twenty replacement substitutions . But the variation across gene pairs is huge. Even a fine-grained statistical model that allows for differences in Ka/Ks among young and old duplicates may explain only 50% of the variance in evolutionary rates. In addition, there may be species-specific differences in Ka/Ks, but detection of such differences is sensitive to how information on gene duplicates is extracted from genomes and on how Ka and Ks are estimated. For example, one of the above studies suggests that recent mammalian duplicates (Ka/Ks = 0.45 for genes with Ks between 0.05 and 0.5) appear to be under lower selective constraints than recent duplicates of Drosophila melanogaster, Caenorhabditis elegans, or Arabidopsis thaliana, where Ka/Ks < 0.3, whereas the other study suggests no such differences.
To determine whether one duplicate evolves faster than the other, one can compare the sequences of both duplicates with that of a related but distant 'outgroup' gene and determine whether one duplicate has diverged to a greater extent than the other. The results may again depend on the organism studied. For example, in bacteria and mammals fewer than 10% of duplicates seem to evolve at different rates . In contrast, a recent study focusing on ancient zebrafish duplicates - most of them developmental genes - found that about 50% of duplicates differ in their rates of evolution . Despite such differences, these results show that it is not generally the case that one duplicate 'holds down the fort', and retains the original function while the other can evolve freely.
Tandemly duplicated genes are known to be subject to gene conversion events that homogenize their sequences . If rampant, gene conversion could substantially distort inferences of selection pressures after gene duplication. How prevalent is gene conversion for non-tandemly duplicated genes? Increasing amounts of sequence information prove helpful in answering this question as well. One group of genes with extremely slow rates of evolution, the histone H3 genes, has received recent attention in this regard . With only three amino-acid differences between animal and plant histone H3 proteins, for example, histones are among the most highly conserved proteins. Does gene conversion contribute to their homogeneity? If so, one would expect that values of Ks between histone gene duplicates would be small - reflecting recent gene conversion - and not dramatically greater than values of Ka. But in organisms ranging from fungi to mammals, Ka and Ks differ by as much as a factor of 60 between non-tandemly clustered histone H3 genes , so evolution by gene conversion is unlikely to be frequent in this family. Another study asked whether yeast (Saccharomyces cerevisiae) gene duplicates show evidence of gene conversion. Part of the assay in this study was based on the observation that measures of codon-usage bias are strongly correlated with the rate of synonymous divergence of yeast genes (because mutations in a highly expressed gene to a synonymous codon for which the respective transfer RNA is rare are deleterious). Only 4 out of 160 yeast duplicates had a synonymous divergence (Ks) less than expected on the basis of their codon-usage bias, showing that gene conversion is rare. In summary, although gene conversion is potentially rampant for some genes, it is most likely to be rare for the vast majority of genes.
Perhaps the most difficult questions about the influence of selection after gene duplication is how frequently beneficial mutations occur. Large amounts of genome sequence information lend themselves to the establishment of databases that document the gene families that have elevated Ka/Ksratios . Mere sequence analysis will probably have a limited impact on answering this question, however, because finding genes with Ka/Ks > 1 is usually not quite enough to make a case for positive selection. Although a particular genome may contain many duplicates with Ka/Ks apparently above one, the observed difference from unity often does not withstand statistical scrutiny. Does this indicate the absence of positive selection after gene duplication? It does not, because positively selected amino-acid substitutions often occur only in a small region of the coding region, too small to be detectable by an elevated Ka/Ks ratio. And several case studies suggest the existence of positive selection for individual gene families, including the opsin visual pigments, primate ribonuclease genes, and triosephosphate isomerases [10,11,12,13]. These studies also show that a strong case for positive selection generally requires integration of information on gene divergence, phylogeny, and protein structure and function.
In summary, genome-scale surveys of gene duplication have the great merit of answering questions about molecular evolution without lingering doubts of statistical bias caused by small samples. They can assess to what extent selection is relaxed after gene duplication, to what extent gene duplicates diverge at different rates, and how abundant gene conversion events are. But their biggest strength - providing summary information about thousands of gene pairs - is also their biggest weakness. Some questions, such as the abundance of beneficial mutations, generally require more information than a crude view of the whole genome can provide. Genome-scale surveys thus draw our attention to their own limitations, which call for an integration of a variety of approaches to understand genome evolution.
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- Van de Peer Y, Taylor JS, Braasch I, Meyer A: The ghost of selection past: rates of evolution and functional divergence of anciently duplicated genes. J Mol Evol. 2001, 53: 436-446. 10.1007/s002390010233.PubMedView ArticleGoogle Scholar
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- Zhang JZ, Rosenberg HF, Nei M: Positive Darwinian selection after gene duplication in primate ribonuclease genes. Proc Natl Acad Sci USA. 1998, 95: 3708-3713. 10.1073/pnas.95.7.3708.PubMedPubMed CentralView ArticleGoogle Scholar | <urn:uuid:af234e41-af0e-4348-8c1b-68150de4ef2f> | 2.875 | 2,268 | Truncated | Science & Tech. | 30.945063 | 95,484,478 |
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A computational model for biosonar echoes from foliage
Gupta, Anupam Kumar
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Since many bat species thrive in densely vegetated habitats, echoes from foliage are likely to be of prime importance to the animals’ sensory ecology, be it as clutter that masks prey echoes or as sources of information about the environment. To better understand the characteristics of foliage echoes, a new model for the process that generates these signals has been developed. This model takes leaf size and orientation into account by representing the leaves as circular disks of varying diameter. The two added leaf parameters are of potential importance to the sensory ecology of bats, e.g., with respect to landmark recognition and flight guidance along vegetation contours. The full model is specified by a total of three parameters: leaf density, average leaf size, and average leaf orientation. It assumes that all leaf parameters are independently and identically distributed. Leaf positions were drawn from a uniform probability density function, sizes and orientations each from a Gaussian probability function. The model was found to reproduce the first-order amplitude statistics of measured example echoes and showed time-variant echo properties that depended on foliage parameters. Parameter estimation experiments using lasso regression have demonstrated that a single foliage parameter can be estimated with high accuracy if the other two parameters are known a priori. If only one parameter is known a priori, the other two can still be estimated, but with a reduced accuracy. Lasso regression did not support simultaneous estimation of all three parameters. Nevertheless, these results demonstrate that foliage echoes contain accessible information on foliage type and orientation that could play a role in supporting sensory tasks such as landmark identification and contour following in echolocating bats. | <urn:uuid:5af9600a-4a9f-47fe-80cb-affa57ebf73e> | 3.234375 | 371 | Academic Writing | Science & Tech. | 14.958512 | 95,484,519 |
An optical digit recognition application, written in MATLAB.
Running The Application
To run the ODR system, run 'ODR.m'. You will be presented with 3 choices:
1 - Load a pre-created network
Use this to load a network file you created before. The file you want to load must have the name 'networks.m'.
2 - Create a network
Use this to create a new ODR network of specified number of hidden nodes and number of training iterations. This created network will be saved with format 'network-<day>-<month>-<year>-<hour>-<minute>-<numHiddeUnits-<numIterations>.m', with time values taken from current time.
3 - Exit the program
Exit the program without doing anything.
To assess which network provides the best recognition, cross validation script tests each network against the generated test data and tells which network provides the least amount of errors. To do cross validation, run 'CrossValidation.m'. The networks to be tested should have format 'network-<numHiddeUnits>-<numIterations>.m' and each network must be added to the list in the script, with each element having string format as '<numHiddeUnits>-<numIterations>'.
Creating Test Data
Test data can be created by running 'CreateTestCases.m' script. You specify the digit to create test cases for and the number of test cases you want to create. The script creates 'mid1test' folder inside the current folder and puts test cases inside. The test case files have the same structure as the provided training data files and has name format as 'test<digit>.txt'.
MATLAB R2013A UNIX (v22.214.171.1244) | <urn:uuid:944445fb-bff2-4ee7-8d40-3f21e2fb0577> | 3.015625 | 384 | Documentation | Software Dev. | 60.690625 | 95,484,539 |
An estimated 93 tons of dead fish washed up on Sakhalin Island in Russia, north of Japan last week.
“The death scale of the Pacific herring in Piltun Bay is enormous,” a spokesman for the regional NGO Ecological Watch of Sakhalin said.
“The death of such an amount of uneven-aged fish of the same species is an abnormal event, and it may be a question of the destruction of a large part of the population of the herring of the bay.”
The event was first reported on June 12:
Fish samples have been sent to Moscow for testing.
“Worlds largest oil companies produce tens of millions of tons of oil every year on Sakhalin,” Russian Environmentalist Dmitry Lisitsyn said. “Compared to them, a few hundred tons of the deceased Pacific herring is a pittance.”
A similar event occurred in the same place in 1999. Tinro Center concluded that “herring on the routes of spawning migrations fell into water layers containing oil or oil products, surfactants and drilling waste. This affected its migration behavior and combined with other adverse environmental factors, causing death of weakened herring.”
Tens of thousands of Far Eastern Sardines, also known as iwashi, beached on the same island in October 2015. Beaches along the southern part of the Tatar Strait were literally carpeted with sardines.
At the time, fish expert Nikolay Kim said the weather conditions had caused ‘strong daily fluctuations’ in water temperature. ‘In the afternoon it is warm, but at night the temperature falls sharply,’ he said. ‘The sardines cannot withstand such fluctuations and can be found in a large number on the shore.’
News agency Interfax – Far East reported that water in the southern part of the Tatar Strait warmed to 20 °C (68 °F), but a recent cyclone led to a sharp decrease in its temperature.
Featured image: Dead Pacific herring washed up on Sakhalin Island, Russia – June 2018. Credit: Dmitry Lisitsyn | <urn:uuid:5b2a72eb-0e40-42bc-98a9-0f8431db3ecb> | 2.65625 | 445 | News Article | Science & Tech. | 46.945 | 95,484,549 |
An Article by Heather Martin
It's always exciting to find uncommon species but after such a long, cold winter and a slow start to Spring it's reassuring to see some familiar common species re-emerging on the occasional warm and sunny May day.
The 18th was one such day. Speckled Yellow moths (Pseudopanthera macularia) fluttered along the main track through our wood, often pausing to rest on foliage at the edges. Their distinctive patterning of brown blotches on a yellow background makes it impossible to confuse them with any other species. They are a common sight in open woodland especially in the south of England from mid-May to late June. The larvae can be found feeding predominantly on Wood Sage (Teucrium scorodonia) between June and August, then the pupa spends the winter either underground or in plant debris.
A much smaller moth with metallic wings and very long antennae - a female Adela reaumurella, was also spotted sitting on a leaf in the sun. This is another common Spring species often seen dancing in small swarms around the outer branches of Hazel and Oak trees. The male has even longer antennae.
Incurvaria masculella. Commonly found in woodland and gardens throughout the country, its larva mines the leaves of Hawthorn.
Pieris napi) dance in a clearing then settle on Bugle flowers (Ajuga reptans) - common maybe but their presence certainly added to our enjoyment of the morning.
What makes these common species precious is the very fact that they can be seen in numbers on warm days, giving us a sense that life is thriving all around us and contributing to our feeling of general well-being.
All pictures by Heather Martin; 21/05/2013 | <urn:uuid:016beb2b-017f-4c5f-b5cf-fe412a10d52d> | 3.125 | 370 | Personal Blog | Science & Tech. | 48.629393 | 95,484,565 |
- Open Access
Secondary dispersal driven by overland flow in drylands: Review and mechanistic model development
© Thompson et al.; licensee BioMed Central Ltd. 2014
Received: 6 December 2013
Accepted: 12 March 2014
Published: 17 April 2014
The Correction article to this article has been published in Movement Ecology 2014 2:14
Seed dispersal alters gene flow, reproduction, migration and ultimately spatial organization of dryland ecosystems. Because many seeds in drylands lack adaptations for long-distance dispersal, seed transport by secondary processes such as tumbling in the wind or mobilization in overland flow plays a dominant role in determining where seeds ultimately germinate. Here, recent developments in modeling runoff generation in spatially complex dryland ecosystems are reviewed with the aim of proposing improvements to mechanistic modeling of seed dispersal processes. The objective is to develop a physically-based yet operational framework for determining seed dispersal due to surface runoff, a process that has gained recent experimental attention. A Buoyant OBject Coupled Eulerian – Lagrangian Closure model (BOB-CELC) is proposed to represent seed movement in shallow surface flows. The BOB-CELC is then employed to investigate the sensitivity of seed transport to landscape and storm properties and to the spatial configuration of vegetation patches interspersed within bare earth. The potential to simplify seed transport outcomes by considering the limiting behavior of multiple runoff events is briefly considered, as is the potential for developing highly mechanistic, spatially explicit models that link seed transport, vegetation structure and water movement across multiple generations of dryland plants.
Seed dispersal, or the process by which seeds are mobilized, transported and eventually come to rest prior to germination forms a critical stage in reproductive biology. It is the main process that determines population migration rates, invasion dynamics, patterns of gene flow and spatial organization of the landscape . Seed dispersal is diverse, encompassing both biotic (animal mediated) and abiotic (physically mediated) processes . Several abiotic dispersal processes such as wind and water-driven seed dispersal are amenable to a theoretical description, using well-established principles from fluid mechanics to describe the seed dispersal as inertial particle transport in turbulent flows[4, 5]. For example, the specific problem of seed dispersal by wind over homogeneous, closed vegetation canopies has been sufficiently advanced to pemit estimates of transport distances over which seed populations are dispersed [3, 6–10]. These solutions depend upon the properties of the dispersed seeds, wind statistics above the vegetation canopy, the seed release height, and the vertical distribution of the canopy leaf area.
This paper modifies the theoretical treatment of seed dispersal to account for the secondary dispersal of seed by overland flow in spatially patchy drylands . The seeds of dryland plants usually lack adaptations that promote long-distance primary dispersal . Seeds undergoing primary dispersal (from plant to the ground) travel only short distances. The distances travelled by fallen seeds (secondary dispersal) have a high probability of being much longer than those travelled in primary dispersal. Thus, secondary dispersal determines the locations in which seeds come to rest and germinate [13–15]. Water [12, 15–19] and wind [13, 20–22] are both abiotic seed transporting vectors for secondary dispersal in drylands. Their relative importance remains a subject of active research, and is likely controlled by the overlap between dispersal periods and the rainy season. While at least one theoretical treatment of secondary dispersal by wind in drylands has been proposed , no attempts to develop a mechanistic model for seed dispersal in overland flow have yet been made. Yet, recent increases in studies exploring water-driven dispersal in drylands [15–19], in modeling overland flow processes in patchy landscapes [24, 25], and in the broader realm of water dispersed seed dynamics (hydrochory) suggest that the time is ripe to develop such theory.
Dispersal of seed via overland flow is clearly a form of hydrochory, and could incorporate both nautochory (the dispersal of floating seeds at the surface of a water column) or bythisochory (dispersal of non-floating seeds along the base of a water column) . Dispersal in overland flow, however, has characteristics that differentiate it significantly from typical hydrochory along a stream network or within wetlands. These characteristics include the following mechanisms: (i) the initiation of dispersal relies on the occurrence of relatively infrequent intense rainfall events that generate sufficient overland flow to move seeds (by comparison, in most streams and rivers, flow is perennial or nearly so, and the initiation of hydrochory relies on primary or secondary transport of seeds to the flow channel); (ii) the termination of dispersal is dictated by seed trapping or the cessation of overland flow (by comparison, stranding of seed on river banks or floating vegetation, or burial of seeds that change their density over time are the primary modes of termination of in-channel hydrochory) [29, 30]; (iii) flow is not confined to the vicinity of the channel network, and consequently (iv) overland flow can lead to long-distance seed dispersal, over shorter length-scales but also a less-constrained areal extent than hydrochory within rivers.
This study proceeds in three parts: (i) a review of the relevant flow generation and seed characteristics that influence secondary dispersal by overland flow; (ii) extension of existing seed transport theories to overland flow in sparse canopies, and an illustration of theoretical results from this extension; and (iii) a discussion of the implications of these results for spatial ecology in drylands.
Overland flow generation in drylands
Bare soils in drylands are directly exposed to rain impact and sunlight, leading to the formation of structural and sedimental soil seals , and biological soil crusts . Together, seals and crusts form a compacted, disturbed layer at the soil surface, characterized by low saturated hydraulic conductivity [33, 34]. They drastically reduce soil infiltrability and lead to the formation of infiltration-excess overland flow [35–39]. Conversely, vegetated patches are characterized by high surface roughness [25, 40] and high infiltration rates , and inhibit the formation of overland flow . The patchy structure of drylands therefore leads to spatially fragmented patterns of overland flow initiation . Pervasive microtopographical variation creates further spatial distinctions between narrow, deep and fast-flowing zones where flow velocities can be 2-7 times higher than their areal averaged counterparts; to broad, shallow, slow-moving zones where flow velocities approach zero [24, 44–46]. The immediate generation of runoff from rainfall events, specifically those of sufficient intensity to exceed local infiltration capacities [42, 47] leads to surface runoff that is highly intermittent through time. Theoretical treatments of the seed-transporting flow field cannot ignore the spatial patchiness in flow initiation and flow characteristics.
The friction factor f varies with surface roughness, h, and with the bulk Reynolds number, Re b = Vh/ν, where ν is the kinematic viscosity of water (about 10 times smaller than its air counterpart). When the flow is fully turbulent, Re b >500 and Manning’s equation is used to link f to the Manning roughness coefficient, which varies only with the surface properties . However, for laminar flow conditions, Re b < 500 and f varies with Re b . The determination of f for vegetated patches is complicated by other factors due to the presence of localized drag forces at the vegetation-water interface (potentially larger than the ground shear stress), but which lie outside the immediate scope of this study. However, analytical formulation linking f to vegetation attributes such as leaf area index, leaf drag, and water level have been derived for the large Re b case . Flow disturbances induced by rainfall events can impact f and even the generation of turbulent kinetic energy that increase the velocity variance around V, although these effects are rarely considered in hydrologic models. The solution to these equations also requires that the flow is sub-critical (i.e. Froude Number Fr < 1) thereby avoiding formation of hydraulic jumps along with their associated energy losses not considered in S f .
Seed dispersal in overland flow
One body of research addressing seed dispersal in overland flow has viewed secondary dispersal as a negative outcome: for instance inhibiting revegetation efforts in degraded landscapes [51, 52], preventing plant colonization of hillslopes and resulting in recruitment in environments that represent sub-optimal seedling habitat . These studies report the rate of seed loss due to overland flow, rather dispersal locations. Another body of research recognizes that secondary dispersal by water may be significant for determining the structure and functioning of dryland ecosystems [13, 53–60]. These studies identify species zonation, seed trapping and transport efficiencies, and explore the long-term and large-scale outcomes of dispersal by water.
Physical properties of seeds from dryland species, and their estimated terminal velocities in water
Dimensions (mm by mm)
Density (kg m-3)
Terminal velocity in water (ms-1)
6.0–6.6 × 1.9–2.22
6.0 mm spheroids3
6-12 × 5 – 124
4 × 0.55
0.68 × 0.406
0.94 × 0.826
Pappophorum spp. a
1.32 × 0.476
1.67 × 0.986
2.45 × 1.186
1.46 × 1.026
1.18 × 1.046
2.27 × 0.986
Vol: 1067 mm3 7
Vol: 0.16 mm3 7
Average of 83 Spanish desert seeds
Vol: 67.91 mm3 7
Seed dispersal by overland flow is influenced by other seed characteristics. Larger seeds are less likely to be mobilized [15, 18, 19, 51, 52]. More intense storms are more likely to mobilize seeds . Several species have adaptations such as awns, hairs, and pappi that enhance seeds trapping , some are preferentially dispersed into cracks , and some excrete mucilage when wet [15, 19, 51, 54]: adaptations that tend to prevent dispersal by water (although some studies suggest that mucilage increases seed buoyancy and promotes dispersal in runoff ).
In summary, several empirical studies suggest that: (i) seeds will float; (ii) transport initiation is a critical stage of dispersal; (iii) transport initiation is less likely for larger seeds; and (iv) adaptations that increase the likelihood of seed trapping influence transport. These common findings provide the minimum input to the development of theoretical descriptions of seed transport in overland flow.
Seed dispersal in overland flow
Inertial particle transport by moving fluids
where ρ f is the density of the fluid (water here), and ρ p is the density of the seed (particle) when wet. Note that where the density of the seed is less than the density of water, as appears to be the case for the vast majority of seeds considered here, this implies a negative reduced gravity, i.e. a positive buoyancy and floating seeds.
where C d is the drag coefficient, A the surface area of the seed, m is the seed mass, V f the velocity vector for the moving water and V p the velocity vector for the seed particle.
Seeds with adaptations that increase their surface area such as wings, therefore experience high drag forces for relatively small velocity differences, and these cause the velocity of the seed to approximate that of the fluid (i.e. the seed is well-coupled to the moving water). Smaller surface areas do not couple seed and fluid velocities tightly, and changes in seed velocity will lag behind changes in fluid velocities for these particles .
The seed acceleration can be estimated from the drag forces at any spatial location, and integrated along the seed’s path to yield its velocity and displacement. This approach relies on coupling the Eulerian flow statistics (which determine V f at any point in space or time) to the Lagrangian description of seed motion. It is therefore known as the Coupled Eulerian Lagrangian Closure model, or CELC [5, 10, 68]. Boundary conditions defining seed mobilization and the termination of transport must be imposed for specific dispersal problems [66, 69]. Note that this framework does not account for cases where the seed or its V p interact with or alter the fluid velocities.
CELC may be run for an ensemble of seeds through Monte Carlo simulations of the travel paths, yielding a probabilistic description of seed transport distances from a single seed source position. The resulting probability density function (PDF) of seed originating from any individual point is known as the dispersal kernel. Kernels provide a parsimonious description of dispersal and can be directly incorporated into spatial models of the plant population, as has been done in a number of recent studies [70, 71].
In the overland flow problem, the dispersal kernel is spatially heterogeneous and will vary for each potential point of seed release depending on the flow experienced locally at that point, and the downslope distance to vegetated patches that intercept flow and seeds. This situation offers three possible approaches for the spatial representation of dispersal: (i) a description of only mean transport lengths initiated from every point in space (at a manageable computational cost, but at the cost of preserving only one moment of the dispersal kernels); (ii) the generation of an individual dispersal kernel for every potential release point, which can then be spatially summed to obtain the final distribution of dispersed seeds throughout the domain (comprehensive, but with a high computational cost); or (iii) in landscapes with strong spatial organization (i.e. a consistent length-scale between vegetated patches) and strong trapping of seed by vegetation, multiple dispersal events may cause the cumulative dispersal lengthscales to converge. In these landscapes, it might be possible to generate an effective dispersal kernel that could be used to approximate seed transport as a low-dimensional basis for modeling - especially if such models are subjected to spatially periodic boundary conditions.
Here the first possibility is explored using CELC to estimate mean seed transport distances given the location of the seeds following primary dispersal. As explored in Section Adapting CELC for Buoyant Seed Transport, the ensemble mean of all seed trajectories provides a reasonable description of the population-level transport because the low velocities of overland flow minimize the potential for turbulent spreading of dispersed seeds (in comparison to wind-dispersal in forested landscapes). A similar approach was adopted by Trakhtenbrot et al. to address the characteristics of seed dispersal from uniform canopies in heterogeneous (hilly) terrain. The cumulative effects of multiple storms on seed distribution are also explored to assess the feasibility of the third case. Although it is not implemented in this study, additional drivers of variability in dispersal length-scale could be readily coupled to CELC and used to drive the definition of spatially-varying kernels for heterogeneous landscapes. Naturally, these additional drivers are site- or problem-specific and thus lie outside the scope of this review.
Adapting CELC for buoyant seed transport
Three adaptations are introduced to modify the CELC framework from its original formulation for wind dispersal over homogeneous canopies to seed dispersal in overland flow. The first is to assume no net vertical seed transport. That is, once the flow depth is large enough, buoyant seeds float on the surface, and fluctuations in the seeds' vertical position simply follow the flow depth. The second adaptation is to account for time variation in the Eulerian flow velocities such that they can be inferred from V and h. In the case of wind dispersal, individual seed flights are short compared to the 30-60 minute periods on which wind statistics are usually pseudo-steady . No such timescale separation exists in the case of overland flow. The third adaptation is to account for spatial dependence of the Eulerian statistics, driven by the spatially patchy nature of runoff in drylands. The modified CELC framework is referred to as the “Buoyant – OBject CELC” model (BOB-CELC). It simplifies CELC by neglecting vertical velocity fluctuations, at the expense of resolving the full space-time variation of the other velocity components. Hence, the strength of BOB-CELC is that unlike the horizontal homogeneity of vegetation and flow assumed in current CELC treatments of dispersal by wind, for overland water flow the vegetation and flow heterogeneity effects are explicitly incorporated.
where P is the rainfall intensity, f the local infiltration capacity, D the storm duration and d the seed diameter. This condition is necessary in all situations, and sufficient in the limit of topographically flat sites where the ponded depth h is not diminished by lateral flows, nor enhanced by flow concentration.
To test whether the assumption that seed trajectories are well represented by the mean seed trajectory (and displacement distance) is valid, we ran simulations where 50 seeds were released at four locations: upslope of a vegetated patch, at the patch boundary, within the vegetated patch and downslope from the vegetated patch. The seeds were routed through BOB-CELC for a 5 cm/hr, 5 minute long storm, and the resulting variance in the spread of seed travel distances computed for seed from each initial location. The variance in these dispersal kernels was, on average 2 mm, with the greatest variance being only 4 mm – in comparison to the average transport distance from each location, which was on the order of 75 m. The five orders of magnitude difference between the transport length and the spread in the seeds suggests that the seed motion is overwhelmingly kinematic and quasi- deterministic in these low-turbulence systems.
This result requires discussion, since the finding of minimal variance in seed dispersal length-scales appears counter-intuitive. This result, however, should not be interpreted as indicating that seed transport in overland flow is entirely deterministic. Instead, it indicates that turbulence within the flow trajectories is not the major source of variance in dispersal length-scales in shallow overland flow. This contrasts markedly with wind dispersal, in which turbulence is a major driver of variability in dispersal length-scales. However, the distinction between the two cases can be readily interpreted in terms of the differences in the Reynolds numbers of the flow: on the order of 100-102 for shallow overland flow, and on the order of 105-106 for wind dispersal: this suggests that travel variances due to turbulence should be many times smaller in overland flow than in wind dispersed cases. However, other sources of variability in dispersal length-scales can and should be considered when modeling seed dispersal in overland flow. Two likely sources of such variability include the time at which dispersal is initiated (the results here assumed simultaneous mobilization of all seeds at a given location), and variability in the termination of transport by the trapping of seeds. Each of these sources of variability can be readily incorporated into BOB-CELC. However, the physical basis for the parameterization of stochastic transport initiation and termination of seeds remains unclear, and further research is required. For this reason, we have retained only the most elementary descriptions of a single transport initiation time, along with a highly simplified treatment of seed trapping as described below.
applied at every timestep while the seed is located within a vegetated zone. Similar probabilistic approaches could be used to describe the effect of seed adaptations that promote trapping. Without detailed data about trapping due to vegetation morphology or seed characteristics, these effects cannot be explored in detail.
Effects of storm, vegetation, hillslope and seed characteristics
To explore the effects of storm, vegetation, hillslope and seed characteristics on transport in a synthetic patchy landscape, a suite of flow scenarios on a linear hillslope covered with two repeating units consisting of a region of bare ground and a large vegetation patch is developed. To solve Equation 1, the roughness and infiltration parameterization are taken from previous studies . These scenarios represent seed transport associated with e.g. banded vegetation in drylands . The size of the vegetated patch is varied as well as the contrast in the infiltration rates between bare and vegetated patches, the slope angle, and storm properties. The boundary conditions applied to the flow were a no-flux boundary condition on the upslope edge of the first bare area (i.e. u B = 0) and a constant-flux boundary condition on the downslope edge of the second vegetation patch (i.e. du B /dt = 0). The no-flow boundary condition can either be considered to represent the condition at a hillslope divide, or, more generally, the condition on bare soils downslope of a vegetated patch that prevents significant lateral discharge of runoff. The constant-flux boundary condition is applied to allow runoff water to evacuate the domain. Model results are presented showing only the second of the repeating units (bare-vegetated), allowing for edge effects from the upslope boundary condition to be dampened.
Spatial consequences of seed dispersal in runoff in drylands
The results show that unsurprisingly, secondary dispersal by overland flow is highly anisotropic and only transports seeds downslope. The detailed modeling approach presented in Figure 5 can be used to examine whether secondary dispersal in overland flow could result in ‘directed’ dispersal, that is preferential dispersal to habitats that may favor seed establishment and recruitment to adulthood [90, 91]. Assuming that in drylands vegetation patches are indicative of favorable habitat, the preliminary results presented here suggest that the answer will depend on storm parameters such as intensity and duration – that might determine whether the flow will be channeled around the vegetation - as well as on the patch spatial organization.
While the results so far provide a mechanism to describe seed dispersal and thus to link generations of plants in space, we have not explicitly simulated the evolution of spatial vegetation patchiness in drylands. Heuristically, downslope trapping of seeds suggests that the anisotropic dispersal could be prescribed with an effective dispersal kernel that localizes the modal dispersal at the bottom edge of vegetated patches. An analogous approach has been used previously to demonstrate the role of secondary dispersal as a stabilizing mechanism in patterned dryland vegetation . The advantage of such kernel-based approaches is that they provide a representation of the net effect of multiple runoff events, and allow simulations to be run at the coarse timescales corresponding to plant growth instead of the single-storm event needed in BOB-CELC. The disadvantage of such averaged representations of seed transport is that the variability between storms is ignored. To account for variations between storms, explicit simulations of runoff, seed dispersal, and ultimately germination and growth are required. These simulations are computationally intensive, but offer the prospect of process fidelity (at least with regards to time-scale matching between process and its representation in models). More mechanistic modeling, such as that performed in order to produce Figure 5, could also be coupled to explicit plant population models. By providing detailed hydrological information (e.g. soil moisture contents at the end of the storm as well as seed locations), mechanistic models of this nature not only act as a valuable basis for simulation, but offer considerable scope for testing predictions. Ultimately, models combining overland flow dynamics with seed dispersal and erosion could prove useful in the design of dryland restoration and revegetation strategies: an area where experimental trials are routinely implemented, but model assisted design remains uncommon [92–95].
Recent developments in modeling seed dispersal and runoff generation in dryland ecosystems offer the potential for representing modes of secondary dispersal associated with overland flow. An extension to the existing CELC modeling framework was proposed (BOB-CELC) that showed qualitative agreement with dispersal behaviors reported in the literature. The framework provides a potential basis for exploring parsimonious representations of seed dispersal in patchy landscapes in which the final seed resting positions are largely tied to the vegetation distribution, as well as a fully mechanistic approach suitable for coupling to spatially and temporally explicit simulations. Despite these promising developments, there remains a clear need for targeted observations to reconstruct dispersal behavior in runoff in different patchy dryland ecosystems. Experiments targeting processes of transport initiation, trapping and termination, exploring the relative importance of and interactions between secondary wind and water dispersal, and linking dispersal processes to germination and growth success would be particularly informative. As particle tracking techniques [96, 97], high resolution imagery and advances in LIDAR for mapping vegetation and water levels continue to improve [99–101], the time is ripe to coordinate experimental and theoretical developments.
Katul acknowledges support from the National Science Foundation (Grant NSF-AGS- 1102227), the United States Department of Agriculture (Grant No. 2011-67003-30222), the U.S. Department of Energy (DOE) through the office of Biological and Environmental Research (BER) Terrestrial Ecosystem Science (TES) Program (Grant No. DE-SC0006967), and the Binational Agricultural Research and Development (BARD) Fund (Grant No. IS- 4374-11C). Svoray acknowledges support from the Israel Science Foundation (ISF) (Grant 1184/11). Thompson acknowledges support from the National Science Foundation (Grant NSF EAR-1331940) and the United States Department of Agriculture through the National Robotics Initiative (Grant 2013-67021-20947). Trakhtenbrot acknowledges support from Vaadia-BARD Postdoctoral Fellowship Award No. FI-470-2012 from BARD, The United States - Israel Binational Agricultural Research and Development Fund.
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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. | <urn:uuid:b9d5b3e0-fa39-43df-b99f-01edfe05f5c3> | 2.65625 | 10,715 | Truncated | Science & Tech. | 39.273362 | 95,484,570 |
The Magellanic Clouds are two irregular dwarf galaxies visible in the Southern Celestial Hemisphere; they are members of the Local Group and are orbiting the Milky Way galaxy. Because they both show signs of a bar structure, they are often reclassified as Magellanic spiral galaxies. The two galaxies are:
Image credit: Primoz Cigler, Joseph Brimacombe,
Ed Dunens and EkantTakePhotos
Stars orbiting the Supermassive Black Hole at our Galactic Center.
This demo shows the observed and predicted orbits of thirteen stars that were used by astronomers at the Keck/UCLA Galactic Center Group to predict the position of a huge black hole at the center of the Milky Way. This data was provided by Andrea Ghez and Jessica Lu.
On the shore of Lake Dumbleyung
This vibrant image from NASA’s Spitzer Space Telescope shows the Large Magellanic Cloud, a satellite galaxy to our own Milky Way galaxy.
Image credit: NASA/JPL-Caltech/STScI
On this day in 1889 was born the astronomer Edwin Hubble!
Edwin Hubble played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology and is regarded as one of the most important astronomers of all time.
Hubble discovered that many objects previously thought to be clouds of dust and gas and classified as “nebulae” were actually galaxies beyond the Milky Way. He used the strong direct relationship between a classical Cepheid variable’s luminosity and pulsation period (discovered in 1908 by Henrietta Swan Leavitt) for scaling galactic and extragalactic distances.
Hubble provided evidence that the recessional velocity of a galaxy increases with its distance from the earth, a property known as “Hubble’s law”, a preliminary version of which was proposed earlier by Georges Lemaître. Hubble’s Law implies that the universe is expanding. A decade before, the American astronomer Vesto Slipher had provided the first evidence that the light from many of these nebulae was strongly red-shifted, indicative of high recession velocities.
Hubble’s name is most widely recognized for the Hubble Space Telescope which was named in his honor, with a model prominently displayed in his hometown of Marshfield, Missouri.
Hubble also devised the most commonly used system for classifying galaxies, grouping them according to their appearance in photographic images. He arranged the different groups of galaxies in what became known as the Hubble sequence .
In 1929 he demonstrated that the galaxies move away at great speed and that this speed increases with the distance. The relationship between velocity and distance from Earth is known as the Hubble Law and the ratio between the two values is known as Hubble’s Constant. If a galaxy is approaching, the light shifts to the blue color and if it is moving away from the light to the red color (Doppler effect). In each case, the relative variation of length is proportional to the speed at which the source moves.
Hubble’s law is the name for the observation in physical cosmology that:
When you hear the name “Hubble”, you probably think of the NASA/ESA Hubble Space Telescope. But, decades before the Hubble Space Telescope, Dr Edwin Powell Hubble revolutionised the field of astronomy. In the newest Hubblecast, we take a look at the life and work of this brilliant American astronomer for whom the Hubble Space Telescope is named.
Probably yes, astronomers believe that practically every galaxy has a black hole in its center, in…
Supermassive Black Hole Sagittarius A*. Animation of the Stellar Orbits around the Galactic Center. | <urn:uuid:0f2afae5-a5f3-43c9-a9a3-8a67bc755534> | 4.1875 | 759 | Content Listing | Science & Tech. | 30.122179 | 95,484,581 |
John Metcalfe is CityLab’s Bay Area bureau chief, based in Oakland. His coverage focuses on climate change and the science of cities.
Climate change, population growth, and infrastructure are all contributing to the rise in billion-dollar disasters in the U.S., according to NOAA.
The brutal, globe-spanning heat that made 2016 the second-warmest year in more than a century of records wasn’t the only recent atmospheric plague on Earth. Last year also witnessed a huge number of costly weather and climate disasters in the U.S., including ferocious wildfires, devastating floods, and a slew of severe, house-splintering storms.
There were 15 disasters in 2016 that caused more than $1 billion in damages, making it the second-hardest-hit year in modern history for these kind of meteorological monsters (right behind the 2011 total of 16 such events). All told these calamities reaped 138 lives and piled up $46 billion in direct costs, according to a NOAA analysis.
Some disasters were widely reported on, such as October’s Hurricane Matthew that’s somehow still causing headaches in Florida and South Carolina. Others might’ve avoided many people’s radars, including floods in West Virginia and around the Gulf and major hailstorms that struck San Antonio and other Texas locales in the spring.
The four inland floods that delivered more than $15 billion in damages (much in Louisiana and Texas) were especially notable, as no year has seen more than two billion-dollar-plus floods since at least 1980. This flood surge could be a sign of things to come as the atmosphere heats up: warm air holds more moisture, and during storms can deliver city-inundating rain bombs.
And a pattern is emerging. In the whole period from 1980 to 2016, there were an average of 5.5 weather events each year that did more than $1 billion of damage (adjusted for inflation), according to NOAA. But in the most recent five years, there were an average of 10.6 events per year. 2005 was the costliest year since 1980, thanks to hurricanes Katrina, Rita, and others. 2012 was the second costliest, due to extreme drought and Hurricane Sandy.
“The increase in population and material wealth over the last several decades are an important factor for the increased damage potential,” according to NOAA:
These trends are further complicated by the fact that many population centers and infrastructure exist in vulnerable areas like coasts and river floodplains, while building codes are often insufficient in reducing damage from extreme events. Climate change is probably also paying a role in the increasing frequency of some types of extreme weather that lead to billion-dollar disasters.
These disasters are now lumped into the 203 events costing more than $1 billion that’ve hammered the U.S. since 1980, which together have cost more than $1.1 trillion. Here’s a highlight reel of 2016 for all to remember, beginning with flooding in Rainelle, West Virginia, about 50 miles southeast of Charleston:
Coastal erosion after Hurricane Matthew in Vilano Beach, Florida:
Automotive damage after a punishing spring hailstorm in San Antonio:
And aerial photos just east of Baton Rouge after (left) and before (right) August’s floods: | <urn:uuid:61652080-e34c-4e8b-83ad-f172ceba36a8> | 3.203125 | 687 | Truncated | Science & Tech. | 46.683834 | 95,484,596 |
What is AgI, NH4NO3, Ni(OH)2, PbO Zn(OH)2 insoluble or soluble and why?© BrainMass Inc. brainmass.com July 17, 2018, 9:22 pm ad1c9bdddf
The solubility rule says:
1.All Ammonium (NH4+) Compounds are soluble. Therefore NH4NO3 is SOLUBLE
2. All Iodide (I-) salts are ...
The solution provides a detailed and step-by-step explanation for the solubility problem. | <urn:uuid:e3e904f6-9e1d-423c-8d61-081db6567812> | 2.703125 | 123 | Truncated | Science & Tech. | 73.642 | 95,484,612 |
The list of potential life-supporting planets just got a little shorter
As the search continues for Earth-size planets orbiting at just the right distance from their star, a region termed the habitable zone, the number of potentially life-supporting planets grows. In two decades we have progressed from having no extrasolar planets to having too many to search.
How would an alien world like this look? That's the question that ASU undergraduate art major Joshua Gonzalez attempted to answer. He worked with Professor Patrick Young's group to learn how to analyze stellar spectra to find chemical abundances, and inspired by the scientific results, he created two digital paintings of possible unusual extrasolar planets, one being Tau Ceti for his Barrett Honors Thesis.
Credit: Joshua Gonzalez
Narrowing the list of hopefuls requires looking at extrasolar planets in a new way. Applying a nuanced approach that couples astronomy and geophysics, Arizona State University researchers report that from that long list we can cross off cosmic neighbor Tau Ceti.
The Tau Ceti system, popularized in several fictional works, including Star Trek, has long been used in science fiction, and even popular news, as a very likely place to have life due to its proximity to Earth and the star's sun-like characteristics. Since December 2012 Tau Ceti has become even more appealing, thanks to evidence of possibly five planets orbiting it, with two of these - Tau Ceti e and f - potentially residing in the habitable zone.
Using the chemical composition of Tau Ceti, the ASU team modeled the star's evolution and calculated its habitable zone. Although their data confirms that two planets (e and f) may be in the habitable zone it doesn't mean life flourishes or even exists there.
"Planet e is in the habitable zone only if we make very generous assumptions. Planet f initially looks more promising, but modeling the evolution of the star makes it seem probable that it has only moved into the habitable zone recently as Tau Ceti has gotten more luminous over the course of its life," explains astrophysicist Michael Pagano, ASU postdoctoral researcher and lead author of the paper appearing in the Astrophysical Journal. The collaboration also included ASU astrophysicists Patrick Young and Amanda Truitt and mineral physicist Sang-Heon (Dan) Shim.
Based upon the team's models, planet f has likely been in the habitable zone much less than 1 billion years. This sounds like a long time, but it took Earth's biosphere about 2 billion years to produce potentially detectable changes in its atmosphere. A planet that entered the habitable zone only a few hundred million years ago may well be habitable and even inhabited, but not have detectable biosignatures.
According to Pagano, he and his collaborators didn't pick Tau Ceti "hoping, wanting, or thinking" it would be a good candidate to look for life, but for the idea that these might be truly alien new worlds.
Tau Ceti has a highly unusual composition with respect to its ratio of magnesium and silicon, which are two of the most important rock forming minerals on Earth. The ratio of magnesium to silicon in Tau Ceti is 1.78, which is about 70% more than our sun.
The astrophysicists looked at the data and asked, "What does this mean for the planets?"
Building on the strengths of ASU's School of Earth and Space Exploration, which unites earth and space scientists in an effort to tackle research questions through a holistic approach, Shim was brought on board for his mineral expertise to provide insights into the possible nature of the planets themselves.
"With such a high magnesium and silicon ratio it is possible that the mineralogical make-up of planets around Tau Ceti could be significantly different from that of Earth. Tau Ceti's planets could very well be dominated by the mineral olivine at shallow parts of the mantle and have lower mantles dominated by ferropericlase," explains Shim.
Considering that ferropericlase is much less viscous, or resistant to flowing, hot, yet solid, mantle rock would flow more easily, possibly having profound effects on volcanism and tectonics at the planetary surface, processes which have a significant impact on the habitability of Earth.
"This is a reminder that geological processes are fundamental in understanding the habitability of planets," Shim adds.
"Tau Ceti has been a popular destination for science fiction writers and everyone's imagination as somewhere there could possibly be life, but even though life around Tau Ceti may be unlikely, it should not be seen as a letdown, but should invigorate our minds to consider what exotic planets likely orbit the star, and the new and unusual planets that may exist in this vast universe," says Pagano.
This work was supported by funding from the NASA Astrobiology Institute and NASA Nexus for Exoplanet System Science.
Image 1 caption: How would an alien world like this look? That's the question that undergraduate art major Joshua Gonzalez attempted to answer. He worked with Professor Patrick Young's group to learn how to analyze stellar spectra to find chemical abundances, and inspired by the scientific results, he created two digital paintings of possible unusual extrasolar planets, one being Tau Ceti for his Barrett Honors Thesis. Credit: Joshua Gonzalez
Image 2 caption: An artist's impression of the Tau Ceti system. Credit: J. Pinfield for the RoPACS network at the University of Hertfordshire, 2012
Mike Pagano, email@example.com
Nikki Cassis, firstname.lastname@example.org
Arizona State University
School of Earth and Space Exploration
College of Liberal Arts and Sciences
Tempe, Arizona USA
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Satellite imagery (or spaceborne photography) are images of Earth or other planets collected by imaging satellites operated by governments and businesses
Pages in category “Satellite imagery“. The following 34 pages are in this category
Remote sensing is the acquisition of information about an object or phenomenon without … For a summary of major remote sensing satellite systems see the overview table. ….. Recent developments include, beginning in the 1960s and 1970s with the development of image processing of satellite imagery. Several research .
Imagery, in a literary text, is an author’s use of vivid and descriptive language to add depth to their work. It appeals to human senses to deepend the reader’s .
Multiple satellite imaging is the process of using multiple satellites to gather more information than a single satellite so that a better estimate of the desired .
A multispectral image is one that captures image data within specific wavelength ranges across …. Unlike other Aerial photographic and satellite image interpretation work, these multispectral images do not make it easy to identify directly the .
Google Earth’s imagery is displayed on a digital globe, which displays the planet’s … The imagery is retrieved from satellites or aircraft.
Aerial photography (or airborne imagery) is the taking of photographs from an aircraft or other ….. for deriving new map data. Google Earth overlays orthophotos or satellite imagery onto a digital elevation model to simulate 3D landscapes.
DigitalGlobe is an American commercial vendor of space imagery and geospatial content, and … It was the world’s first high-resolution commercial imaging satellite to collect panchromatic (black-and-white) images with 0.8 m resolution and .
Space imaging may refers to: Astronomical image processing of objects usually beyond the Solar System; Images taken by Earth satellites; Images processed . | <urn:uuid:eddd7af8-2c5c-4d01-a11b-00a99c2b17f0> | 3.625 | 381 | Content Listing | Science & Tech. | 16.89186 | 95,484,622 |