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Could the same results be obtained by exposing deep-learning AI to fewer examples? Boston-based startup Gamalon developed a new technology to try to answer just that, and this week, it released two products that utilize its new approach.
Gamalon calls the technique it employed Bayesian program synthesis. The program also refines its knowledge as further examples are provided, and its code can be rewritten to tweak the probabilities.
While this new approach to programming still has difficult challenges to overcome, it has significant potential to automate the development of machine-learning algorithms.
“Probabilistic programming will make machine learning much easier for researchers and practitioners,” explained Brendan Lake, an NYU research fellow who worked on a probabilistic programming technique in 2015.
Unlike Google’s version, which relied on sketches it had previously seen to make predictions, Gamalon’s app relies on probabilistic programming to identify an object’s key features.
One product, the Gamalon Structure, using Bayesian program synthesis to recognize concepts from raw text, and it does so more efficiently than what’s normally possible. | <urn:uuid:c2959889-a655-4807-9833-991a9bb38815> | 3.078125 | 230 | News Article | Software Dev. | 23.781515 | 95,615,811 |
Infrared spectra of mineral grains from primitive meteorites could be useful for comparison with astronomical infrared spectra since some of their grains might be similar to those formed in the planet-forming disks around young stars or in the envelopes surrounding late-type stars. To assess the usefulness of meteorite spectra, olivine grains separated from primitive meteorites have been analyzed using FTIR microscope techniques in the 2-16 mu m wavelength range. The sub-micron sizes of the grains made a complex preparation process necessary. \ud Five characteristic bands were measured near 11.9, 11.2, 10.4, 10.1, and 10.0 mu m. The results of 59 analyses allow the calculation of band positions for meteoritic olivines as a function of their iron and magnesium contents. Comparison of the meteoritic results with astronomical data for comets and dust around young and old stars, which exhibit bands similar to the strongest infrared bands observed in the grains (at 11.2 mu m), show that the spectral resolution of the astronomical observations is too low to ascertain the exact iron and magnesium (Mg:Fe) ratio of the dust in the 8-13 mu m wavelength range
To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request. | <urn:uuid:b8b3e6a1-2bf6-43e6-af93-e5507ab76cc1> | 3.1875 | 265 | Academic Writing | Science & Tech. | 44.641285 | 95,615,813 |
Rapidly changing geomagnetic field variations constitute a natural\ud hazard, for example in navigation and, through geomagnetically induced\ud currents, to power grids and pipeline networks. To understand this\ud hazard we have continuous magnetic measurements across the world\ud for typically less than 100 years. Much of the older data is also in\ud analogue form, or is only available digitally as hourly or daily magnetic\ud indices or mean levels. So it may not yet be clear what the true\ud extremes in geomagnetic variations are, particularly on time scales -\ud seconds to minutes - that are relevant for estimating the hazard to\ud technological systems.\ud \ud We therefore use a number of decades of one minute samples of\ud magnetic data from observatories across Europe, together with the\ud technique of 'extreme value statistics’ to explore estimated maxima in\ud field variations in the horizontal strength and in the declination of the\ud field. These maxima are expressed in terms of the variations that might\ud be observed once every 100 and 200 years. We also examine the\ud extremes in one-minute rates of change of these field components over\ud similar time scales.\ud \ud The results should find application in both hazard assessment for\ud technologies and in navigation applications. The results can also be\ud used to more rigorously answer the often-asked question: “just how\ud large can geomagnetic storms and field variations be? | <urn:uuid:d661c5d3-e245-49eb-a38b-786d3c7998a2> | 3.09375 | 308 | Academic Writing | Science & Tech. | 23.976662 | 95,615,814 |
What you see here is the Trifid Nebula, a vast cloud of gas and dust in space.
In my last post, we explored why it looks the way it does. We discovered that the pink hues of emission nebulae are caused when extremely hot nearby stars “excite” the gas of the nebula itself to emit its own light, which our eyes perceive as pink.
The haze of blue to the right, on the other hand, is the result of light from hot young stars nearby getting scattered among the nebula’s dust particles. It looks blue for the same reason the sky looks blue. We call nebulae like this reflection nebulae.
And the black wisps of dark nebulae are hardly as ominous as they look; they’re simply ordinary clouds of gas and dust, ordinary nebulae, that we can only see because they’re silhouetted by brighter objects in the background.
But nebulae, for all their different names, are actually a heck of a lot more similar than you might think. Continue reading
What makes a star shine bright?
Much earlier on—probably months ago now—I explained how something called the proton-proton chain generates massive amounts of energy within stars, and enables them to fuel whole solar systems. That’s the battery of a star.
We’ll address the proton-proton chain later, when we start talking about star life cycles. We’ve still got some talk about nebulas and interstellar space to go before we get that far. For now, what’s important is that the proton-proton chain depends on high density.
That is, stars will have the strongest batteries if they have very dense interiors. It doesn’t really matter how dense their middles and atmospheres are. But conditions in their cores must be very dense.
You’ll find, if you study stars closely, that there is a definite relation between their densities, masses, and luminosities. Continue reading
The simplest approach to chemistry is to start basic.
Not basic as in acids and bases, ha-ha…sorry, bad chemistry joke.
I mean basic as in, what the heck even is chemistry?
I admit that I’m better versed in astronomy than chemistry. I’ve studied chemistry for exactly one year of my life—last year, 12th grade. Astronomy, on the other hand, has been my strong suit and my passion for several years.
For me, these Wednesday posts are like a refresher course. I don’t actually remember everything I’ve learned. Good thing I bought a copy of the textbook.
So, I’ll start simple—because chemistry is the study of breaking complex things down to the simplest bits possible. It’s the opposite of astronomy. Astronomy studies huge, mind-blowing phenomena. Chemistry, on the other hand…is mind-blowingly small.
It’s the study of matter. Continue reading | <urn:uuid:ed8b83ba-049c-48ca-a051-fa3090b12448> | 3.296875 | 642 | Truncated | Science & Tech. | 60.32691 | 95,615,817 |
Genes are sequences of DNA that can be broken into functional segments. They also produce a biologically active product, such as a structural protein, enzyme or nucleic acid. By piecing together segments of existing genes in a process called molecular cloning, scientists develop genes with new properties. Scientists splice genes in the lab and insert the DNA into plants, animals or cell lines.
Why Splice Genes?
Although some night say it's prudent to leave nature alone, gene splicing offers many advantages for society. Scientists are by far its most frequent users, studying the function of genes and gene products. They add new genes to organisms to make crop plants disease resistant or more nutritious.
Gene therapy, an active topic of research, provides a new and customized way to fight genetic diseases. This approach is especially useful when small-molecule drugs do not exist. Scientists also use gene splicing to produce protein-based drugs that improve medical care.
Gene Splicing Process
A gene is spliced by assembling different gene segments and DNA sequences into a product called a chimera. Scientists join these snippets in a circular piece of DNA called a plasmid.
Scientists use a complex process to clone genes from an organism's DNA. However, in decades of scientific research, most genes already exist in a plasmid stored in a lab somewhere. Gene segments are cut out of the original DNA and joined to make a new gene. Then, researchers check the new sequence to make sure that its position and orientation in the DNA molecule are correct.
The coding region of the gene defines the product that is produced by the cell; this is almost always a protein. The coding region of a gene can be changed with naturally occurring or artificial mutations. These changes to a cell's DNA change how the cell functions. Scientists can add a tag sequence to track and study gene products in an organism. Gene splicing also creates new gene sequences to create proteins with multiple or entirely new functions.
Not all parts of a gene control production of an end product. Non-coding regions are equally important in determining gene function.
Promoter sequences control the ways that genes are expressed in a cell. These sequences determine whether a gene is always expressed, processes the cell produces a particular nutrient or whether a cell is under stress. The promoter also controls which cells a gene is expressed in. For example, a bacterial promoter will not work if it is moved into a plant or animal cell.
Enhancer sequences control whether the cell produces many or only a few units of the gene's end product. Other sequences determine how long and how many products linger in the cell and whether the cell excretes end products. | <urn:uuid:228c447b-5266-4884-8af8-284790098fbc> | 4.0625 | 543 | Knowledge Article | Science & Tech. | 43.53129 | 95,615,830 |
How Embryonic Stem Cells Maintain Their Identity
News Apr 26, 2006
Two studies in the April 21, 2006 Cell report details of the "genetic program" that affords embryonic stem cells the flexibility to give rise to any cell type in the body.
Both groups identified mechanisms by which the embryonic stem cells of mice or humans keep from going down any one particular developmental path-that of muscle or nervous tissue, for example-while remaining "poised for activation."
Human embryonic stem cells can be kept in an undifferentiated state and selectively induced to form many specialized cell types, which could potentially replace cells lost or damaged by disease.
The findings may therefore aid in the realization of embryonic stem cells' therapeutic potential for regenerative medicine, according to the researchers, while furthering scientists' understanding of early development.
In one of the studies, Richard Young of the Whitehead Institute, and his colleagues, found that a member of the so-called Polycomb-group proteins is distributed across a special set of 200 developmental genes in human embryonic stem cells.
Polycomb proteins are known to silence gene activity through chemical, or "epigenetic," modifications that alter the way that DNA is packaged into chromatin.
"We saw that the Polycomb protein preferred to occupy genes for most of the human developmental regulators to repress their activity," Young said.
"These genes encode transcription factors that control development downstream of the embryo."
"This makes sense because were the developmental transcription factors 'on,' they would cause the embryonic stem cells to differentiate into specific cell types."
"It's an exciting result because it appears that the Polycomb proteins are generally responsible for maintaining developmental genes in an 'off' state."
Developmental genes found in association with the Polycomb protein were also occupied by histone proteins chemically modified at sites known to repress gene activity, they found.
Histones-the chief proteins of chromatin-act as spools around which DNA winds and play a role in gene regulation.
Furthermore, they found, the silenced developmental genes became preferentially activated in human embryonic stem cells undergoing differentiation.
The findings help to explain earlier results in mice deficient for Polycomb proteins, Young said. The embryonic stem cells of those mice were "extremely unstable" and tended to specialize or die in culture, he said.
"The results also add to the team's earlier finding, reported in Cell last year, that a trio of transcription factors--Oct4, Sox2, and nanog-are key regulators of embryonic stem cells' pluripotency and self-renewal," he said.
Pluripotency refers to the cell's ability to develop into multiple cell types. The three factors apparently work together to activate pathways critical for stem cell identity, while repressing those leading to differentiation.
The researchers now report that the stem cell regulators Oct4, Sox2, and nanog co-occupy "a significant subset" of the developmental genes that are repressed by the Polycomb protein, further supporting a link between repression of developmental regulators and embryonic stem cell identity.
"This paper connects the two classes of embryonic stem cell regulators and provides a foundation for understanding the basic circuitry underlying human development," Young said.
In the second paper, Bradley Bernstein of Massachusetts General Hospital and Harvard Medical School, and his colleagues, report the discovery of a unique chromatin structure that marks key developmental genes in embryonic stem cells.
The structure, which they call "bivalent domains," includes a pattern of chemical modification with both repressive and activating characteristics.
"In differentiated cells, chromatin is either 'on' or 'off' in accordance with the identity of that particular cell-rarely or never in between," Bernstein said.
"In embryonic stem cells, we found a totally different structure. The developmental genes of stem cells bear evidence of both active and repressive states. It's the first time this has been seen."
The genes appeared to be in a silent state, he explained, but with an activating influence that could allow them to turn on rapidly as needed.
He suggested that by preserving the potential of key developmental genes, the bivalent domains may contribute to the unique ability of embryonic stem cells to form the many different tissues in the body.
When the researchers examined the state of the same genes in a collection of differentiated cell types, they found that the bivalent domains had been replaced by either repressive or activating modifications, in accordance with the cell's identity.
Muscle cells, for example, must express the master genes for muscle, while silencing those specifically required for other cell types, Bernstein explained.
The team suggests that a comprehensive inventory of the presence or absence of bivalent domains over key developmental genes may provide valuable markers of cell identity and differentiation potential, in both health and disease.
Bernstein said the findings also suggest that therapies that modify cells' epigenetic state might prove useful in the field of regenerative medicine.
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Regenerative Medicine Meets Clever Engineering to Accommodate Bone GraftsNews
Personalized bone grafts developed to repair bone defects from disease or injuryREAD MORE | <urn:uuid:2ac29f79-0e22-41ef-add8-70b87db5578c> | 3.140625 | 1,128 | News Article | Science & Tech. | 15.950787 | 95,615,843 |
Positive and negative impacts of solar energy
The sun is the principal reason that we have life on this Earth. If it had not been for the sun, we would have nothing, from water to plants to the various life forms that roam the earth. It forms the source of the endless supply of energy that is instrumental in ensuring that all life on Earth continues to flourish. Besides, it has been, for many years now, one of the cleanest sources of energy that can substitute the more perishable and infinitely more dangerous fossil fuel. Currently, it supplies only a small fraction of the total energy output of the world, but efforts are underway to become more dependent on solar energy. On the other hand, there is enough debate about some practical aspects such as cost and performance. In this article, we will look at arguments from both sides.
Positive impacts of solar energy:
First of all, let us look at the good that solar energy promises to do to us.
The most obvious factor, of course, is the availability of solar energy. Solar energy comes directly from the sun; in fact, we use it all the time without having to install massive structures to capture it. People across the world dry their clothes and shoes in the sun, the rays of the sun keep us warm and provide us with natural light, and plants directly absorb solar energy to make food for themselves. It can even be used to light a fire. It is for the bigger purposes, like creating electricity, that we need to put in more effort. And the best part is that there is no chance of losing out on this energy source ever. When the sun actually dies, the lack of solar energy will not be of any concern to us, since life on earth will have ceased to exist long before that happens.
Greener than fossil fuels
Global warming and air pollution are two of the biggest threats to life on earth at present. It is a well known fact that fossil fuels are some of the most prominent sources of greenhouse gases, which lead to global warming. Vehicles and industries that run on greenhouse gases contribute immensely to the rise in temperature and air pollution, thanks to the fact that there is a huge amount of carbon emissions from such structures. Needles to say, this poses an immense threat to the atmosphere and the ecosystem. Solar energy, on the other hand, is one of the most sustainable forms of energy, since it does not emit any greenhouse gas by itself.
Lower costs in the long run
Solar is a very modular form of energy, which means that it is composed of a bunch of different installations that are linked together. It can also be implemented on multiple scales, from thermal plants, rooftop solar paneling on buildings, and street lightings. The initial installation cost is pretty high at present, although it can be hoped that this will significantly reduce once the usage of solar power becomes more widespread. However, the cost of maintenance is significantly lower than the other forms of less sustainable energy once the initial installation process is complete. It is especially more feasible in rural areas where grid energy can be either unavailable or incur extremely high costs.
Negative impacts of solar energy:
All said and done, however, we need to understand that solar energy does come with its own set of challenges.
Continuing in the trend of the previous argument, it cannot be denied that producing solar energy can indeed be quite costly. To begin with, production of solar energy requires the building and maintenance of technology that is extremely expensive, which takes up initial costs to sky high levels. Again, solar energy can only be produced during the day, and is dependent on the weather and the season as well. If it is cloudy, or during the rainy season, the amount of solar energy produced will be significantly lower, and this in turn will not only be impractical in meeting the constant energy requirements, but will also be unable to recover costs.
Might pose health risks
Solar units pose significant health risks to people and animals. Solar panels are composed of pure silicon. Silicon itself is harmless, but silicon dust, if inhaled, can lead to significant respiratory troubles. Solar collectors also generate harmful chemicals that can pose significant risk on constant exposure. Besides, improper handling of the photovoltaic cells might release their component materials to the environment, to disastrous results.
There is no doubt that solar energy is certainly an immensely sustainable source of power. With fossil fuel reserves depleting on an ongoing basis, it is necessary that we move on to more sustainable sources, with solar energy being one of them. There are challenges, surely, but it is important that we find ways to circumvent them.Labels:https://yandex ru/clck/jsredir?from=yandex ru;search;web;;&text=&etext=1844 lMl0o_tPJPNTNTyCPzqLGbHfthDCVAjA15YkAQobk4hDJpQKWweddFggeDhJYeMsv0DSZhF_4r9SWjRvMRk5iQ 89fc18df272060fdbb63d4d39d4b9f998d164615&uuid=&state=_BLhILn4SxNIvvL0W45KSic, https://yandex ru/clck/jsredir?from=yandex ru;search;web;;&text=&etext=1833 uPi7n2RZd-BDFneunSrwJ3lnB13bIBP-8ktNRMHdamu61MRopCExuI_ftHz50NrS6DqSi9J0h3MJiHFExva4Yw 692b07a244ccfa3f4e95c6f7cf02d1b2f0f2ec44&uuid=&state=_BLhILn4SxNIvvL0W45KSic, https://yandex ru/clck/jsredir?from=yandex ru;search;web;;&text=&etext=1834 mn3nyZ8OvKDgP85QuMp74606wCSwKSO4UJpaEeCo6vD8E18N4h_B6gZo8aw0r6CKbIsVhhYqgBSrdmJbVTDnrQ 9ccbb34a7f3e03b9fea5c47583265d4e3f64ea10&uuid=&state=_BLhILn4SxNIvvL0W45KSic, https://yandex ru/clck/jsredir?from=yandex ru;search;web;;&text=&etext=1837 nGxSqE6ZTTIcb271-87uo1BBm498Kuo461iGvSiaIw6ucBKRt7LnqSGTCaw5Esq-wn0_fnkqnGxgHTn3nVw3zw caa54813a9a814a8d20c2bf6c6518d6f21951519&uuid=&state=_BLhILn4SxNIvvL0W45KSic, https://yandex ru/clck/jsredir?from=yandex ru;search;web;;&text=&etext=1837 ojem9UtHEaIlo1IWyH1LaRcpiiyhpOMlzRt_bSIuoNmZKB4OgTrwqk71GTvqqnp83VLRhWHRrTLQp-7m0QGu7A b9dbbdb8ef73919d3d715318287e602bda6e6d96&uuid=&state=_BLhILn4SxNIvvL0W45KSic, https://yandex ru/clck/jsredir?from=yandex ru;search;web;;&text=&etext=1838 J5T3NK0VFNofVBz2ZKvnZzV904kyexKa4E63DQ6mV6AK4wnl2LAXJQhMppn_P9lyS_6K6zP7N7_-w49p3gaFaw d5dc5460d924e6037b83b6083a235cc1e23294ec&uuid=&state=_BLhILn4SxNIvvL0W45KSic, | <urn:uuid:1729368d-35f0-4c79-afb2-ebe850b8b226> | 3.234375 | 1,839 | Truncated | Science & Tech. | 39.143898 | 95,615,852 |
From the highest peak in the continental United States, Mt. Whitney at 14,000 feet in elevation, to the 10,000-foot-peaks near Lake Tahoe, scientific evidence from the University of Nevada, Reno shows the entire Sierra Nevada mountain range is rising at the relatively fast rate of 1 to 2 millimeters every year.
"The exciting thing is we can watch the range growing in real time," University of Nevada, Reno's Bill Hammond, lead researcher on the multi-year project to track the rising range, said. "Using data back to before 2000 we can see it with accuracy better than 1 millimeter per year. Perhaps even more amazing is that these miniscule changes are measured using satellites in space."
Miniscule as they may be, the data indicate that long-term trends in crustal uplift suggest the modern Sierra could be formed in less than 3 million years, which is relatively quick when compared to estimates using some geological techniques.
Hammond and his colleagues in the University's Nevada Geodetic Laboratory and University of Glasgow use satellite-based GPS data and InSAR (space-based radar) data to calculate the movements to this unprecedented accuracy. The calculations show that the crust moves upward compared to Earth's center of mass and compared to relatively stable eastern Nevada.
The data may help resolve an active debate regarding the age of the modern Sierra Nevada of California and Nevada in the western United States. The history of elevation is complex, exhibiting features of both ancient (40 million years) and relatively young (less than 3 million years) elevation. The "young" elevation is the uplift Hammond and colleagues have tracked.
"The Sierra Nevada uplift process is fairly unique on Earth and not well understood." Hammond said. "Our data indicate that uplift is distributed along the entire length of the 400-mile-long range, between 35 and 40 degrees north latitude, that it is active, and could have generated the entire range is less than 3 million years, which is young compared to estimates based on some other techniques. It basically means that the latest pulse of uplift is still ongoing."
Possibly contributing to the rapid uplift is the tectonic extension in Nevada and a response to flow in the mantle. Seismologists indicate the mountain range may have risen when a fragment of lower plate peeled off the bottom of the lithosphere allowing the "speedy" uplift, like a ship that has lost its keel. In comparison, other ranges, such as the Alps or Andes, are being formed in an entirely different process caused by contraction as two plates collide.
"We've integrated GPS and InSAR measurement techniques, drawing from experience we developed in the past five years in our work with tectonic deformation, to see how the Sierra is gradually being pushed upwards," Hammond said. "Combined with more GPS stations, and more radar data, detecting motions in the Earth is becoming more precise and ubiquitous. We can see the steady and constant motion of the Sierra in addition to episodic events such as earthquakes."
Hammond's team includes Geoff Blewitt, Hans-Peter Plag and Corné Kreemer from the University of Nevada, Reno's College of Science and Zhenhong Li of the Centre for the Observation and Modeling of Earthquakes, Volcanoes and Tectonics, School of Geographical and Earth Sciences, University of Glasgow in the UK.
GPS data for Hammond and his team's research is collected through the team's MAGNET GPS Network based at the University of Nevada, Reno plus more than 1200 stations from the NSF EarthScope Plate Boundary Observatory and more than 10,000 stations from around the entire planet. These stations include hundreds that cover Nevada, California, Oregon, and Washington. The space-based radar data comes from the European Space Agency with support from NASA.
This research was funded in the United States by the National Science Foundation and NASA and in the United Kingdom by the Natural Environment Research Council.
Their paper, "Contemporary Uplift of the Sierra Nevada, western United States, from GPS and InSAR Measurements" will be published in the peer-reviewed journal Geology in July and has just been made available online.
For more information on Hammond, go to http://www.nbmg.unr.edu/Staff/Hammond.html. For the Nevada Geodetic Laboratory go to http://geodesy.unr.edu.The University of Nevada, Reno has the largest GPS data-processing center in the world, which processes information from about 10,000 stations around the globe continuously, 24/7. The Nevada Geodetic Laboratory has all publicly available GPS data going back to 1996 and reprocesses all 15-million data files as new data streams come in – every 30 seconds – solving for tens of thousands of parameters at once. It enables real-time positioning for any users. People around the world use it extensively for research such as modeling earthquakes and volcanoes. The information is freely available to anyone on the Internet.
Mike Wolterbeek | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:a8e347cb-a231-43dd-990f-578ac2810785> | 4.125 | 1,616 | Content Listing | Science & Tech. | 39.819032 | 95,615,858 |
The oldest ecological experiment in the world, set up almost 150 years ago to see whether inorganic fertilisers could produce more grass than traditional animal manures, is becoming an important source of evidence on the impact of climate change on genetic variation in plants.
Speaking at the British Ecological Society’s Annual Meeting, being held at Manchester Metropolitan University on 9-11 September 2003, Professor Jonathan Silvertown of the Open University will explain what the Park Grass Experiment has taught ecologists over the past century and how this uniquely long dataset has shed new light on many ecological problems, including the link between the genetics and population dynamics of species.
Set up in 1856, three years before Charles Darwin published his Origin of Species, the Park Grass Experiment is a hay meadow at Rothamsted Research to which a series of different fertiliser treatments have been applied annually. As well as measuring the yield of hay from each plot, ecologists have also measured the change in species composition in the meadow, and kept samples of the hay cut from it over the years.
Becky Allen | alfa
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:d8e2b198-1f41-4313-9b1e-84e9f626e772> | 3.53125 | 817 | Content Listing | Science & Tech. | 36.17382 | 95,615,859 |
SCAR offers significant time and cost savings compared to the standard approach for carbon dating and could be useful for a host of other applications such as measuring emissions from fossil fuels or certifying the amount of biogenic content in biofuels.Faster, cheaper carbon dating Current carbon dating processes require researchers to send a sample to a large facility with an accelerator mass spectrometer and then wait several weeks to get results back.An accelerator then increases the kinetic energy of the carbon ions to 10-30 million electron volts and moves them through a tube where a powerful electromagnet makes them change direction. Because carbon-14 decays over time, the amount of it in a sample indicates the age of the sample.How much their path bends depends on their mass: Lighter ions bend more. Penn State will soon be home to an accelerator mass spectrometer (AMS) that will allow researchers all over the country to do high-precision carbon dating to address questions about Earth's past and present.
Then enter the ‘name’ part of your Kindle email address below. Note you can select to send to either the @free.or @variations.
Accelerator mass spectrometry measures the amount of carbon-14, or radiocarbon, present in a sample, which can be used to calculate its age.
Around the world, only about 100 facilities house this equipment.
The team reanalyzed two milk teeth, which were discovered in the Grotta del Cavallo site in 1964 and previously classified as Neanderthal.
They showed, using micro CT scanning and extensive comparative work, that the specimens are anatomically modern human. | <urn:uuid:4f917196-06df-4a86-bfd7-a3f3d80f4c09> | 3.453125 | 335 | Truncated | Science & Tech. | 39.765787 | 95,615,865 |
Leahy, L and Legge, SM and Tuft, K and McGregor, HW and Barmuta, LA and Jones, ME and Johnson, CN, Amplified predation after fire suppresses rodent populations in Australia's tropical savannas, Wildlife Research, 42, (8) pp. 705-716. ISSN 1035-3712 (2016) [Refereed Article]
Journal compilation copyright CSIRO 2015
Context: Changes in abundance following fire are commonly reported for vertebrate species, but the mechanisms causing these changes are rarely tested. Currently, many species of small mammals are declining in the savannas of northern Australia. These declines have been linked to intense and frequent fires in the late dry season; however, why such fires cause declines of small mammals is unknown.
Aims: We aimed to discover the mechanisms causing decline in abundance of two species of small mammals, the pale field rat, Rattus tunneyi, and the western chestnut mouse, Pseudomys nanus, in response to fire. Candidate mechanisms were (1) direct mortality because of fire itself, (2) mortality after fire because of removal of food by fire, (3) reduced reproductive success, (4) emigration, and (5) increased mortality because of predation following fire.
Methods: We used live trapping to monitor populations of these two species under the following three experimental fire treatments: high-intensity fire that removed all ground vegetation, low-intensity fire that produced a patchy burn, and an unburnt control. We also radio-tracked 38 R. tunneyi individuals to discover the fates of individual animals.
Key results: Abundance of both species declined after fire, and especially following the high-intensity burn. There was no support for any of the first four mechanisms of population decline, but mortality owing to predation increased after fire. This was related to loss of ground cover (which was greater in the high-intensity fire treatment), which evidently left animals exposed to predators. Also, local activity of two predators, feral cats and dingoes, increased after the burns, and we found direct evidence of predation by feral cats and snakes.
Conclusions: Fire in the northern savannas has little direct effect on populations of these small mammals, but it causes declines by amplifying the impacts of predators. These effects are most severe for high-intensity burns that remove a high proportion of vegetation cover.
Implications: To prevent further declines in northern Australia, fire should be managed in ways that limit the effects of increased predation. This could be achieved by setting cool fires that produce patchy burns, avoiding hot fires, and minimising the total area burnt.
|Item Type:||Refereed Article|
|Keywords:||Canis lupus dingo, Felis catus, fire ecology, northern Australia, prescribed burning, Pseudomys nanus, Rattus tunneyi, small mammals, invasive species, landscape management|
|Research Division:||Environmental Sciences|
|Research Group:||Environmental Science and Management|
|Research Field:||Conservation and Biodiversity|
|Objective Group:||Flora, Fauna and Biodiversity|
|Objective Field:||Flora, Fauna and Biodiversity at Regional or Larger Scales|
|Author:||Leahy, L (Ms Lily Leahy)|
|Author:||McGregor, HW (Dr Hugh McGregor)|
|Author:||Barmuta, LA (Associate Professor Leon Barmuta)|
|Author:||Jones, ME (Associate Professor Menna Jones)|
|Author:||Johnson, CN (Professor Christopher Johnson)|
|Funding Support:||Australian Research Council (LP100100033)|
|Web of Science® Times Cited:||28|
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Common name: Ohio shrimp
available through www.itis.gov
Size: Females are larger than males, reaching 110 mm TL (Bowles et al. 2000)
Native Range: Macrobrachium ohione is the most widely distributed and abundant of the six river shrimp species in the United States (Bowles et al., 2000) and originally was described from the Ohio River. It also is found in the middle and lower Mississippi River from Illinois to Louisiana, west to Oklahoma and Texas, in the Atlantic drainage from Virginia to northern Florida, and in the Gulf region in Alabama and Mississippi (Bowles et al., 2000; Hobbs and Lodge, 2010).
Interactive maps: Point Distribution Maps
Puerto Rico &
Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Macrobrachium ohione are found here.
Table last updated 5/25/2018
† Populations may not be currently present.
Ecology: This shrimp inhabits primarily freshwater rivers and streams; however, their life cycle is associated with estuarine waters for reproduction (Bowles et al., 2000).
This species is amphidromous, where adults migrate downstream to spawn near estuaries, and juveniles swim back upstream and live as adults in freshwater (Bowles et al. 2000). Females, which are larger than males, can reach 110 mm in total length and are gray to green in color with light blue spots (Bowles et al., 2000). Females can produce 6,000–24,000 eggs with a lifespan of only 2 years (Huner, 1977).
Means of Introduction: Most likely a bait bucket introduction. There has been a commercial fishery throughout its native range for bait as well as for human consumption for many years (Bowles et al., 2000; Bauer and Delahoussaye, 2008).
Impact of Introduction: Probably minimal impacts as this species is on the decline as a result of human impacts such as impoundments, river channelization, pollution, commercial fishing, and exotic predators (Barko and Hrabik, 2004; Bowles et al., 2000; Bauer and Delahoussaye, 2008; Hobbs and Lodge, 2010).
References: (click for full references)
Barko, V.A., and R.A. Hrabik. 2004. Abundance of Ohio shrimp (Macrobrachium ohione)
and glass shrimp (Palaemonetes kadiakensis)
in the unimpounded upper Mississippi River. American Midland Naturalist 151(2):265—273.
Bauer, R.T., and J. Delahoussaye. 2008. Life history migrations of the amphidromous river shrimp Macrobrachium ohione from a continental large river system. Journal of Crustacean Biology 8(4):622—632.
Bowles E.E., K. Aziz, and C.L. Knight. 2000. Macrobrachium (Decapoda: Caridea: Palaemonidae) in the contiguous United States—A review of the species and an assessment of threats to their survival. Journal of Crustacean Biology 29:158—171.
Hobbs, H. H. and D. M. Lodge. 2010. Decapoda. Pages 901-967 in Thorp, J. H. and A. P Covich (eds.), Ecology and Classification of North American Freshwater Invertebrates, Third Edition, Academic Press, Amsterdam.
Idelberger, Chuck - personal communication, 2012, Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, Charlotte Harbor Field Laboratory.
Revision Date: 6/3/2013
Benson, A.J., 2018, Macrobrachium ohione (S. I. Smith, 1874): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=2878, Revision Date: 6/3/2013, Access Date: 7/18/2018
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information. | <urn:uuid:ebc11576-39e1-429b-9c9c-7140b457ecbb> | 3.375 | 986 | Knowledge Article | Science & Tech. | 55.160007 | 95,615,931 |
Join Eve Porcello for an in-depth discussion in this video Spread operators, part of Learning ECMAScript 6.
- The spread operator does a lot of…powerful things with three small dots.…The spread operator can turn the…elements of an array into arguments of a function call,…or into elements of an array literal.…Let's take a look at this.…I'm going to create two arrays,…one called cats, and one called dogs,…and each of these arrays is going to…contain three strings, so tabby, Siamese,…and then for our dogs, we'll use…golden retriever,…pug, and schnauser.…
Great, next I want to create an…array of strings called animals.…Inside of this we'll use whale,…giraffe, snake,…and coyote.…So let's say we want to take our…cats and our dogs, and add them to the animals array.…We could do this by simply using their variable names.…I'll add cats here, and dogs in this position here.…
And then if we console log animals,…we should see these items, but notice…here we see whale, giraffe, array…three snake, array three coyote.…What we're doing here is we're…seeing the dogs and cats appear as a…subarray, an array within an array.…If we want to add the array elements…
- What is ECMAScript?
- Transpiling ECMAScript with Babel and Babel-node
- Using the let and const keywords
- Creating strings with template strings
- Enhancing object literals
- Working with ES6 classes and class inheritance
Skill Level Beginner
Q: The Babel API is out of date. How do I proceed with the course?
A: We are updating the course. In the meantime, you can install the babel-cli package and then install the presets that you need to follow along with the tutorials.
1. What Is ECMAScript 6 (ES6)?
2. Transpiling ES6
3. ES6 Syntax
4. ES6 Functions & Objects
5. Asynchronous Features
6. ES6 Classes
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Properties of Light Can be Controlled by Nanostructures
News Mar 14, 2016
A theoretical study based on computational simulations conducted by the UPV/EHU's Nano-bio Spectroscopy Research Group in collaboration with the Japanese research centre AIST, has shown that the intensity of ultraviolet light that is made to pass through a graphene nano-ribbon is modulated with a terahertz frequency. So we are seeing the opening up of a new field of research into obtaining terahertz radiation that has a whole host of applications.
The UPV/EHU's Nano-bio Spectroscopy Research Group led by Ángel Rubio, a UPV/EHU professor in the Department of Materials Physics and director of the Max Planck Institute for Structure and Dynamics of Matter in Hamburg, has simulated the converting of ultraviolet light into radiation in the terahertz range by making it pass through a graphene nano-ribbon, and has put forward a new compact device designed to generate radiation of this type based on the phenomenon discovered. The research, conducted in collaboration with the research group led by Yoshiyuki Miyamoto of the National Institute of Advanced Industrial Science and Technology (AIST) of Japan, has appeared in the prestigious journal Nanoscale, published by the Royal Society of Chemistry (United Kingdom).
Low-frequency terahertz radiation has a broad range of applications, such as the characterisation of molecules, materials, tissues, etc. However, right now it is difficult to manufacture small, efficient, low-cost devices to produce terahertz radiation. This phenomenon "extends the range of applicability of radiation of this type to many other spheres in which it was not being used," explained Ángel Rubio, "owing to the fact that one would have to resort to much bigger radiation sources".
The starting point of a new field of research
To carry out this simulation, they used graphene nano-ribbons: strips cut out of sheets of graphene. In the research they concluded that UV light that exerts an effect on the nano-ribbon emits a totally different radiation (terahertz) perpendicular to the incident light. This phenomenon "opens up the possibility of generating structures that will allow the frequency range to be changed using different nanostructures," explained Prof Rubio. "A new field of research is being opened up".
Now that the existence of the phenomenon has been demonstrated, "it would be necessary to see if the same thing can be done with a different type of light source," explained Ángel Rubio. In the research they used a high-intensity laser pointer so that the simulation would be correct, but it should be possible to use "more accessible light sources", he specified. What is more, another step to be taken in this field would be "to use a set of nanostructures instead of a single one to produce an actual device."
The UPV/EHU group has worked on the proposal of the idea and its implementation in code that allows a simulation to be made on the computer, while the Japanese research centre AIST has been responsible for the numerical calculations. The researchers have used novel simulation techniques of first principles, methods in which the predictive capacity is very high: the behaviour of a material is predicted without using external parameters. "The simulation techniques have reached a point," concluded Rubio, "where systems that are later shown to actually behave in the same way experimentally can be predicted".
Magnetized Wire Could be used to Detect Cancer in PeopleNews
Scientists at Stanford used the wire to capture free-floating tumor cells in the blood, a technique that soon could be used in humans to yield an earlier cancer diagnosis.READ MORE
The Perfect Terahertz Beam - Thanks to the 3D PrinterNews
Scientists have succeeded in shaping terahertz beams with extremely high precision. All that is needed for this is a simple plastic screen from a 3D printer.READ MORE | <urn:uuid:54f266ac-a486-4591-afd1-d9513035d364> | 3 | 813 | News Article | Science & Tech. | 23.290356 | 95,615,937 |
Air Pressure can vary at any particular point on the Earth depending on the density of the air Density = mass / volume
Where is air pressure higher, up in the mountains ordown in thevalley?
http://www.youtube.com/watch?v=GWEyFbyv Elc&feature=related Air Pressure and Altitude
This bottle was photographed at 3600m (left) then again at sea level (right) At sea level, because air is compressible, the weight of all that air above us compresses the air around us, making it denser.We all live underneath a huge ocean ofair that is several miles deep: theatmosphere.The pressure on our bodies is about thesame as ten meters of sea waterpressing down on us all the time.
Density = Mass / Volume Warm air is less dense than coolair. Warm air rises. Cool air sinks. Air at high altitudes is less dense than air at lower altitudes.
Factors that affect Air PressureTemperature Water Vapor Elevation
TEMPERATURE AND AIR PRESSURE Molecules HEAT move fasterLESS AIR MovePRESSURE apart, become fewer and weigh less
HIGHTEMPERATURE, LOW AIRPRESSURELOWTEMPERATURE, HIGH AIRPRESSURE
AMOUNT OF WATER VAPOR consists of air and water molecules
More water vapor meansless air molecules (more water molecules) LOW AIR PRESSURE DRY AIR = HIGH AIR PRESSURE
High pressure generallymeans fair weather Air mass in upper atmosphere No clouds Warm, moi st airLayer of Air cannot rise
Low pressure generally means cloudy, rainy weather Warm airAir masses rises, cloudsmove apart form
High Pressure System: Indicates clear, calmWeather map conditions with reduced chance of precipitation. Drier air usually results in a greater range of high and low temperatures.Low pressure system: Increasedcloudiness, winds, temperatures, and chanceof precipitation.
Measuring Air Pressure Types of BarometerAir Mercury BarometerPressure Aneroidis measuredby aninstrument
Air pressureincreases, column of mercuryrises Air pressure decreases, colu mn of mercury drops
High Pressure:Rising or steady - Continued fairSlowing falling - FairRapidly falling - Cloudy, WarmerMedium pressure:Rising or steady - Same as presentSlowing falling - Little changeRapidly falling - Precipitation likelyLow Pressure:Rising or steady - Clearing, coolerSlowing falling - PrecipitationRapid falling - Storm
Factors Affecting Air Pressure FACTOR Increase/Decrease Air PressureDensityDensityTemperatureTemperatureWater VaporWater VaporAltitudeAltitude
At the top of a mountain How does air pressure you drank a bottle of affect scuba diving?water, sealed it, but imploded on yourway down. Why? A rising barometer A series of hot, humid indicates a spell of days is preceded by a cool dry weather. falling barometer.A southern, coastal areas tend to have Rapidly droppinglower air pressure than an inland area temperatures arefarther north. accompanied by a rising barometer.You are planning a Why would a seriousPicnic and check the athlete decide to trainbarometer, which is at a high altitude?falling. Why should youcancel the picnic?You are hiking Mount Everest How does a hot airand find it hard to breathe at balloon work?a high altitude. | <urn:uuid:245d3e8c-d993-4b36-b805-2fa248ed293c> | 3.734375 | 710 | Knowledge Article | Science & Tech. | 20.596873 | 95,615,949 |
(3) Lorentz Force
- We know that force acting on any charge of magnitude q moving with velocity v inside the magnetic field B is given by
F=q(v X B)
and this is the magnetic force on charge q due to its motion inside magnetic field.
- If both electric field E and magnetic field B are present i.e., when a charged particle moves through a reagion of space where both electric field and magnetic field are present both field exert a force on the particle and the total force on the particle is equal to the vector sum of the electric field and magnetic field force.
F=qE+q(v X B) (4)
- This force in equation(4) is known as Lorentz Force.
- Where important point to note is that magnetic field is not doing any work on the charged particle as it always act in perpendicular direction to te motion of the charge.
(4)Motion of Charged Particle in The Magnetic Field
- As we have mentioned earlier magnetic force F=(vXB) does not do any work on the particle as it is perpendicular to the velocity.
- Hence magnetic force does not cause any change in kinetic energy or speed of the particle.
- Let us consider there is a uniform magnetic field B perpendicular to the plane of paper and directed in downward direction and is indicated by the symbol C in figure shown below.
- Now a charge particle +q is projected with a velocity v to the magnetic field at point O with velocity v directed perpendicular to the magnetic field.
- Magnetic force acting on the particle is
F=q(v X B) = qvBsinθ
Since v is perpendicular to B i.e., angle between v and B is θ=90 Thus charged particle at point O is acted upon by the force of magnitude
and the direction of force would be perpendicular to both v and B
- Since the force f is perpendicular to the velocity, it would not change the magnitude of the velocity and the peffect of this force is only to change the direction of the velocity.
- Thus under the action of the magnetic force of the particle will more along the circle perpendicular to the field.
- Therefore the charged particle describe an anticlockwise circular path with constant speed v and here magnetic force work as centripetal force. Thus
where radius of the circular path traversed by the particle in the magnetic in field B is given as
thus radius of the path is proportional to the momentum mv pof the charged particle.
- 2πr is the distance traveled by the particle in one revolution and the period T of the complete revolution is
T=2 πr /v
time period T is
and the frequency of the particle is f=1/T=qB/2πm (7)
- From equation (6) and (7) we see that both time period and frequency does not dependent on the velocity of the moving charged particle.
- Increasing the speed of the charged particle would result in the increace in the radius of the circle. So that time taken to complete one revolution would remains same.
- If the moving charged particle exerts the magnetic field in such a that velocity v of particle makes an angle θ with the magnetic field then we can resolve the velocity in two components
vparallel : Compenents of the velocity parallel to field
vperpendicular :component of velocity perpendicular to magnetic field B
- The component vpar would remain unchanged as magnetic force is perpendicular to it.
- In the plane perpendicular to the field the particle travels in a helical path. Radius of the circular path of the helex is
Class 12 Maths
Class 12 Physics | <urn:uuid:161bc6c2-7d94-4f0b-bc52-137572fcefa3> | 4.3125 | 774 | Tutorial | Science & Tech. | 44.942835 | 95,615,984 |
Demystifying the Event Loop
The event loop plays an important role in Vert.x for writing highly scalable and performant network applications.
The event loop is inherited from the Netty library on which Vert.x is based.
We often use the expression running on the event loop, it has a very specific meaning: it means that the current Thread is an event loop thread. This article provides an overview of the Vert.x event loop and the concepts related to it.
The golden rule
When using Vert.x there is one Vert.x golden rule to respect:
Never block the event loop!
The code executed on the event loop should never block the event loop, for instance:
using a blocking method directly or, for instance, reading a file with the
java.io.FileInputStreamapi or a JDBC connection.
doing a long and CPU intensive task
When the event loop is blocked:
Vert.x will detect it and log a warn:
The event loop must not be blocked, because it will freeze the parts of the applications using that event loop, with severe consequences on the scalability and the throughput of the application.
Beyond the event loop, Vert.x defines the notion of a context. At a high level, the context can be thought of as controlling the scope and order in which a set of handlers (or tasks created by handlers) are executed.
When the Vert.x API consumes callbacks (for instance setting an
HttpServer request handler), it associates a callback handler
with a context. This context is then used for scheduling the callbacks, when such context is needed:
if the current thread is a Vert.x thread, it reuses the context associated with this thread: the context is propagated.
otherwise a new context is created for this purpose.
However there is one case where context propagation does not apply: deploying a Verticle creates a new context for this Verticle, according to the deployment options of the deployment. Therefore a Verticle is always associated with a context. Any handler registered within a verticle - whether it be an event bus consumer, HTTP server handler, or any other asynchronous operation - will be registered using the verticle’s context.
Vert.x provides three different types of contexts.
Event loop context
Multi-threaded worker context
Event loop context
An event loop context executes handlers on an event loop: handlers are executed directly on the IO threads, as a consequence:
an handler will always be executed with the same thread
an handler must never block the thread, otherwise it will create starvation for all the IO tasks associated with that event loop.
This behavior allows for a greatly simplified threading model by guaranteeing that associated handlers will always be executed on the same thread, thus removing the need for synchronization and other locking mechanisms.
This is the type of context that is the default and most commonly used type of context. Verticles deployed without the worker flag will always be deployed with an event loop context.
When Vert.x creates an event loop context, it chooses an event loop for this context, the event loop is chosen via a round robin algorithm. This can be demonstrated by creating a timer many times:
The result is:
As we can see we obtained different event loop threads for each timer and the threads are obtained with a round robin policy. Note that the number of event loop threads by default depends on your CPU but this can be configured.
An event loop context guarantees to always use the same thread, however the converse is not true: the same thread can be used by different event loop contexts. The previous example shows clearly that a same thread is used for different event loops by the Round Robin policy.
The default number of event loop created by a Vertx instance is twice the number of cores of your CPU. This value can be overriden when creating a Vertx instance:
Worker contexts are assigned to verticles deployed with the worker option enabled. The worker context is differentiated from standard event loop contexts in that workers are executed on a separate worker thread pool.
This separation from event loop threads allows worker contexts to execute the types of blocking operations that will block the event loop: blocking such thread will not impact the application other than blocking one thread.
Just as is the case with the event loop context, worker contexts ensure that handlers are only executed on one thread at any given time. That is, handlers executed on a worker context will always be executed sequentially - one after the other - but different actions may be executed on different threads.
A common pattern is to deploy worker verticles and send them a message and then the worker replies to this message:
The previous example clearly shows that the worker context of the verticle use different worker threads for delivering the messages:
However the same thread can be used by several worker verticles:
The same worker verticle class can be deployed several times by specifying the number of instances. This allows to concurrently process blocking tasks:
Workers can schedule timers:
Again the timer thread is not the same than the thread that created the timer.
With a periodic timer:
we get a different thread for each event:
Since the worker thread may block, the delivery cannot be guaranteed in time:
Just like event loop, the size of the worker thread pool can be configured when creatin a Vertx instance:
Multi-threaded worker context
Multi-threaded contexts are assigned to verticles deployed with the multi-threaded option enabled. Whereas standard worker contexts execute actions in order on a variety of threads, the multi-threaded worker context removes the strong ordering of events to allow the execution of multiple events concurrently. This means that the user is responsible for performing the appropriate concurrency control such as synchronization and locking.
Dealing with contexts
Using a context is usually transparent, Vert.x will manage contexts implicitly when deploying a Verticle, registering an Event Bus handler, etc… However the Vert.x API provides several ways to interact with a Context allowing for manual context switching.
The current context
Vertx.currentContext() methods returns the current context if there is one, it returns null otherwise.
We get obviously
null no matter the Vertx instance we created before:
Current context is null
Now the same from a verticle leads to obtaining the
Creating or reusing a context
vertx.getOrCreateContext() method returns the context associated with the current thread (like
otherwise it creates a new context, associates it to an event loop and returns it:
Note, that creating a context, will not associate the current thread with this context. This will indeed not change the nature of the current thread! However we can now use this context for running an action:
getOrCreateContext from a verticle returns the context associated with the Verticle:
Running on context
io.vertx.core.Context.runOnContext(Handler) method can be used when the thread attached to the context needs
to run a particular task on a context.
For instance, the context thread initiates a non Vert.x action, when this action ends it needs to do update some state and it needs to be done with the context thread to guarantee that the state will be visible by the context thread.
Running with context : io.vertx.core.impl.EventLoopContext@69cdd6d8 Current context : null Runs on the original context : io.vertx.core.impl.EventLoopContext@69cdd6d8
vertx.runOnContext(Handler<Void>) is a shortcut for what we have seen before: it calls the
getOrCreateContext method and schedule a task for execution via the
Before Vert.x 3, using blocking API required to deploy a worker Verticle. Vert.x 3 provides an additional API for using a blocking API:
Calling blocking block from Thread[vert.x-eventloop-thread-0,5,main] Computing with Thread[vert.x-worker-thread-0,5,main] Got result in Thread[vert.x-eventloop-thread-0,5,main]
While the blocking action executes with a worker thread, the result handler is executed with the same event loop context.
The blocking action is provided a
Future argument that is used for signaling when the result is obtained,
usually a result of the blocking API.
When the blocking action fails the result handler will get the failure as cause of the async result object:
Blocking code failed java.lang.RuntimeException at org.vietj.vertx.eventloop.ExecuteBlockingThrowingFailure.lambda$null$0(ExecuteBlockingThrowingFailure.java:19) at org.vietj.vertx.eventloop.ExecuteBlockingThrowingFailure$$Lambda$4/163784093.handle(Unknown Source) at io.vertx.core.impl.ContextImpl.lambda$executeBlocking$2(ContextImpl.java:217) at io.vertx.core.impl.ContextImpl$$Lambda$6/1645685573.run(Unknown Source) at io.vertx.core.impl.OrderedExecutorFactory$OrderedExecutor.lambda$new$180(OrderedExecutorFactory.java:91) at io.vertx.core.impl.OrderedExecutorFactory$OrderedExecutor$$Lambda$2/1053782781.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:745)
The blocking action can also report the failure on the
Obviously executing a task from the blocking action on the context will use the event loop:
Calling blocking block from Thread[vert.x-eventloop-thread-0,5,main] Computing with Thread[vert.x-worker-thread-0,5,main] Running on context from the worker Thread[vert.x-eventloop-thread-0,5,main]
This API is somewhat similar to deploying a worker Verticle, although its purpose is to execute a single blocking operation from an event loop context.
Execute blocking for any particular verticle instance uses the same context as that instance.
By default, if you call
executeBlocking multiple times in any particular instance they will be executed in the order you
called them. If we didn’t do that you’d get into a mess, e.g. if you did an insertBlocking to insert
some data into a table, followed by another to select from that table, then there’d be no guarantee in which
order they occurred so you might not find your data.
When several blocking tasks are submitted, the current implementation picks an available worker for executing the first task, after its execution, it will execute any pending tasks. After the executions of all the tasks, the worker stops and goes back in the worker pool.
It is possible to execute also unordered blocks, i.e the blocks can be executed in parallel by setting the
ordered argument to
Determining the kind of context
The kind of a context can be determined with the methods:
the nature of the context does not guarantee the nature of the thread, indeed the
Determining the kind of thread
As said earlier, the nature of the context impacts the concurrency. The
executeBlocking method can even change
use a worker thread in an event loop context. The kind of context should be properly determined with the static methods:
When the Vert.x API needs a context, it calls the
vertx.getOrCreateContext() method, when the Vert.x API is used
in a context, for instance when deploying a Verticle. This implies that any service created from this Verticle
will reuse the same context, for instance:
Creating a server
Creating a client
Creating a timer
Registering an event bus handler
Such services will call back the Verticle that created them at some point, how this happens is according to the context: the context remains the same, however its nature has a direct impact on the concurrency as it govers the threading model:
Deployed as a worker, no exclusion is required, however the changes must be visibles between threads, pretty much like this:
When Vert.x is embedded like in a main Java method or a junit test, the thread creating Vert.x can be any kind of thread, but it is certainly not a Vert.x thread. Any action that requires a context will implicitly create an event loop context for executing this action.
When several actions are done, there will use different context and there are high chances they will use a different event loop thread.
Current thread is Thread[vert.x-eventloop-thread-1,5,main] Current thread is Thread[vert.x-eventloop-thread-0,5,main]
Therefore accessing a shared state from both servers should not be done!
When the same context needs to be used then the actions can be grouped with a
Current thread is Thread[vert.x-eventloop-thread-0,5,main] Current thread is Thread[vert.x-eventloop-thread-0,5,main]
Now we can share state between the two servers safely.
Vert.x Core apis
Vert.x API consumes handlers and assign them to context, this section provides a quick overview of the Vert.x Core APIs.
TCP servers (HttpServer and NetServer) can run with both event loop and worker contexts. A TCP server consumes a context for the various handlers it uses.
A worker server uses under the hood an event loop for its IO operations, however the worker context is used for calling the registered handlers. Consequently a worker server can block directly, when it happens, this will not have consequences on the underlying event loop, however it does impact directly the server, as this particular server will be blocked: of course the server can be scaled to many workers to handle multiple blocking requests concurrently, this is the classic multithreaded server model.
TCP clients (HttpClient and NetClient) can run with both event loop and worker contexts. Clients don’t have a particular context assigned. A context is instead assigned every time a connection or a request is done.
Every time a timer or periodic is created, a context is assigned, this context is then used when the timer or periodic fires. Event bus or worker contexts are allowed.
A context is assigned when an handler is registered for consuming a message, it can be a registered consumer or registering a message reply handler. Event bus or worker contexts are allowed. | <urn:uuid:2b6fb595-f01d-4654-a373-f6c747fbe2bd> | 2.546875 | 3,116 | Documentation | Software Dev. | 53.204765 | 95,615,999 |
New analysis supports mangrove forests, tidal marshes and seagrass meadows as effective climate buffers
In the global effort to mitigate carbon dioxide levels in the atmosphere, all options are on the table--including help from nature. Recent research suggests that healthy, intact coastal wetland ecosystems such as mangrove forests, tidal marshes and seagrass meadows are particularly good at drawing carbon dioxide from the atmosphere and storing it for hundreds to thousands of years.
This figure illustrates the efficiency of (L-R) mangrove forests, salt marshes and seagrass beds as reservoirs for carbon. More carbon dioxide is taken up from the atmosphere (green arrows) than is re-released (black arrows), while a substantial amount is stored in soils (red arrows) for hundreds to thousands of years if left undisturbed.
Credit: Howard et al., 2017, Frontiers in Ecology and the Environment
Policymakers are interested to know whether other marine systems--such as coral reefs, kelp forests, phytoplankton and fish--can mitigate climate effects. A new analysis co-authored by a University of Maryland scientist suggests that, while coastal wetlands serve as effective "blue carbon" storage reservoirs for carbon dioxide, other marine ecosystems do not store carbon for long periods of time.
The research paper, published February 1, 2017 in the journal Frontiers in Ecology and the Environment, also notes that coastal wetlands can help protect coastal communities from storm surges and erosion. Coastal wetland areas are easier for governments to manage compared with ecosystems that reside in international waters, further adding to the strategic value of coastal wetlands in the fight against climate change.
"We compared many different coastal ecosystems and have made a clear case for including coastal wetlands in discussions about greenhouse gas mitigation," said Ariana Sutton-Grier, an assistant research scientist at UMD's Earth System Science Interdisciplinary Center and a co-lead author of the research paper. "Coastal wetlands store a lot of carbon in their soils and are important long-term natural carbon sinks, while kelp, corals and marine fauna are not."
The research paper integrates previous data on a variety of coastal and marine ecosystems to determine which systems are best suited to mitigate climate effects. To make this assessment, Sutton-Grier and her colleagues evaluated how effectively each ecosystem captures carbon dioxide--for example, by plants using it to build their branches and leaves--and how long the carbon is stored, either in plant tissues or in soils.
Coastal wetlands outperformed other marine systems in just about every measure. For example, the researchers estimated that mangrove forests alone capture and store as much as 34 metric tons of carbon annually, which is roughly equivalent to the carbon emitted by 24 million passenger cars in a year. Estimates for tidal marshes and seagrass meadows vary, because these ecosystems are not as well mapped globally, but the total for each could exceed 80 metric tons per year.
All told, coastal wetlands may capture and store more than 200 metric tons of carbon per year globally. Importantly, these ecosystems store 50-90 percent of this carbon in soils, where it can stay for thousands of years if left undisturbed.
"When we destroy coastal wetlands, for coastal development or aquaculture, we turn these impressive natural carbon sinks into additional, significant human-caused greenhouse gas sources," said Sutton-Grier, who is also an ecosystem science adviser for the National Ocean Service at the National Oceanic and Atmospheric Administration.
The researchers' goal is to help inform resource managers and policymakers where to focus their limited resources to have the greatest impact on climate mitigation. The new analysis acknowledges that other ecosystems, such as coral reefs and kelp forests, provide valuable storm and erosion protection, key fish habitat and recreation opportunities, and thus deserve protection. But their capacity to store carbon over the long term is limited.
"A common question I get from coastal managers and other stakeholders is whether oyster reefs, coral and kelp are effective 'blue carbon' habitats," said Stefanie Simpson, a co-author of the paper and manager of the Blue Carbon program at the nonprofit organization Restore America's Estuaries. "This paper highlights the role all of these ecosystems have in the carbon cycle, while calling out our coastal habitats--marsh, seagrass and mangroves--for their role as significant and long-term carbon stores."
Researchers have often looked to terrestrial forests as carbon sinks as well. But most forests do not store substantial amounts of carbon in their soils. As such, the researchers believe that coastal "blue carbon" habitats may stand alone as the most efficient biological reservoirs of stored carbon on Earth.
"The concept of 'blue carbon' has focused scientists and stakeholders on the tremendous potential of managing marine ecosystems for climate mitigation," said Patrick Megonigal, associate director for research at the Smithsonian Environmental Research Center, who reviewed an early draft of the manuscript but was not directly involved in the work. "This analysis takes a big step forward by explaining why coastal wetland ecosystems are particularly attractive for carbon-based management."
This work includes contributions from: Ariana Sutton-Grier (the University of Maryland and the National Oceanic and Atmospheric Administration); Jennifer Howard and Emily Pidgeon (Conservation International); Dorothee Herr (the International Union for the Conservation of Nature); Joan Kleypas (the National Center for Atmospheric Research); Emily Landis and Elizabeth Mcleod (the Nature Conservancy); and Stefanie Simpson (Restore America's Estuaries).
The research paper, "Clarifying the role of coastal and marine systems in climate mitigation," Jennifer Howard, Ariana Sutton-Grier, Dorothee Herr, Joan Kleypas, Emily Landis, Elizabeth Mcleod, Emily Pidgeon, and Stephanie Simpson, was published February 1, 2017 in the journal Frontiers in Ecology and the Environment.
This work was supported by the National Oceanic and Atmospheric Administration (Award No. NA14NES4320003), the Nature Conservancy, the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, the International Union for the Conservation of Nature, and the Prince Albert II de Monaco Foundation. The content of this article does not necessarily reflect the views of these organizations.
Media Relations Contact: Matthew Wright, 301-405-9267, email@example.com
About the College of Computer, Mathematical, and Natural Sciences
The College of Computer, Mathematical, and Natural Sciences at the University of Maryland educates more than 7,000 future scientific leaders in its undergraduate and graduate programs each year. The college's 10 departments and more than a dozen interdisciplinary research centers foster scientific discovery with annual sponsored research funding exceeding $150 million.
Matthew Wright | EurekAlert!
Investigating cell membranes: researchers develop a substance mimicking a vital membrane component
25.05.2018 | Westfälische Wilhelms-Universität Münster
New approach: Researchers succeed in directly labelling and detecting an important RNA modification
30.04.2018 | Westfälische Wilhelms-Universität Münster
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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Intro to SqlAlchemy
SQLAlchemy is a defacto framework for working with relational databases in Python. It was created by Mike Bayer in 2005. SQLAlchemy allows you to work with databases from different vendors like MySQL, MS-SQL, PostgreSQL, Oracle, SQLite, and many others.
Why use SQLAlchemy #
The most exciting feature of SQLAlchemy is its ORM. An ORM or Object Relational Mapper allows us to work with database using Object Oriented code rather than writing SQL queries. Another great benefit we get from using a framework like SQLAlchemy is that no matter which database we use our underlying code will remain the same. This makes it easy to migrate from one database from another without rewriting the application code.
SQLAlchemy has another component called SQLAlchemy Core. The Core is just a smooth abstraction over the traditional SQL. The Core provides a SQL Expression Language which allows us to generate SQL statements using Python constructs. Unlike ORM which revolves around model and objects, SQL Expression revolves around tables, columns, indexes etc (just like plain old SQL). SQL Expression Language closely resembles SQL but it is standardized so that you can use it across many different databases. You can use SQLAlchemy ORM and SQLAlchemy Core independently or together depending upon what you want to accomplish. Behind the scenes, SQLAlchemy ORM uses SQLAlchemy Core.
So Which one should you use SQLAlchemy Core or ORM?
The whole point of having an ORM is to make working with database easy. In the process, it also adds some additional overhead. However, for most applications, this overhead is not much unless you are working with large amounts of data. For most project SQLAlchemy ORM would be enough but If you writing an application where you will be handling a huge amount of data (like in a database warehouse) or you want to have more control over query or you are an SQL purist and prefer to work directly with rows and columns use core.
Who Uses SQLAlchemy #
- Fedora Project
and many more.
In order to go through this tutorial, you should have a basics understanding of Python and SQL. For a quick refresher on Python checkout our Python tutorial. For SQL search the web. | <urn:uuid:f51f3271-0c70-4691-8cc0-496c8c4092a2> | 2.828125 | 468 | Tutorial | Software Dev. | 43.904572 | 95,616,022 |
Only 3% of the world's water is fresh. And 99% of this is either frozen in glaciers and pack ice or is buried in aquifers. The remainder is found in lakes, ponds, rivers, and streams.
Lakes and Ponds
Deep lakes contain three distinct zones, each with its characteristic community of organisms.
Fig. 22.214.171.124 Littoral zone
The zone close to shore. Here light reaches all the way to the bottom. The producers are plants rooted to the bottom and algae attached to the plants and to any other solid substrate. The consumers include
- tiny crustaceans
- insect larvae
- frogs, fish, and turtles.
This is the layer of open water where photosynthesis can occur. As one descends deeper in the limnetic zone, the amount of light decreases until a depth is reached where the rate of photosynthesis becomes equal to the rate of respiration. At this level, net primary production no longer occurs.
The limnetic zone is shallower in turbid water than in clear and is a more prominent feature of lakes than of ponds.
Life in the limnetic zone is dominated by
- floating microorganisms - called plankton
- actively swimming animals - called nekton
The producers in this ecosystem are planktonic algae. The primary consumers include such animals as microscopic crustaceans and rotifers - the so-called zooplankton. The secondary (and higher) consumers are swimming insects and fish. These nekton usually move freely between the littoral and limnetic zones.
Many lakes (but few ponds) are so deep that not enough light reaches here to support net primary productivity. Therefore, this zone depends for its calories on the drifting down of organic matter from the littoral and limnetic zones. The profundal zone is chiefly inhabited by primary consumers that are either attached to or crawl along the sediments at the bottom of the lake. Such bottom-dwelling animals are called the benthos. The sediments underlying the profundal zone also support a large population of bacteria and fungi. These decomposers break down the organic matter reaching them, releasing inorganic nutrients for recycling.
Where there is a pronounced change of seasons, the warming of the surface of the lake in the summer prevents this water from mixing with deeper water. This is because warm water is less dense than cold.
The surface water becomes enriched in oxygen some from the air above it and the rest - because it is in the limnetic zone - from photosynthesis. But the water in the profundal zone - eing removed from both these sources - becomes stagnant. In the fall, however, as the surface water cools, it becomes denser and sinks to the bottom — carrying oxygen with it.
A similar phenomenon occurs when the ice melts in the spring.
Rivers and Streams
The habitats available in rivers and streams differ in several ways from those in lakes and ponds.
- Because of the current, the water is usually more oxygenated.
- Photosynthesizers play a minor role in the food chains here; a large fraction of the energy available for consumers is brought from the land; e.g., in falling leaves.
Oceans, like lakes, can be described in terms of zones. There are many parallels between the two but unfortunately a separate vocabulary is used for each. | <urn:uuid:2a054aa0-6ae5-4ead-85d0-b3ea47e719bb> | 4.09375 | 701 | Knowledge Article | Science & Tech. | 45.098382 | 95,616,059 |
Why is the Integral an Anti-derivative?
We will use the following definitions:
Anti-Derivative : The anti-derivative of a function is a function such that .
Integral (area definition) : The integral of of is the area under the curve from to .
Let us define the area under the curve from some starting point (it’s arbitrary) to as . Now we calculate . It is left to the reader to show:
Dividing by and taking the limit approaches zero we get.
Thus, the integral of is the anti-derivative of .
By drawing a sample curve of and using the formula for the area of a trapezoid, show that:
Hint: For small enough, the path from to is a line.
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Introspect and display the logger tree inside "logging"
Introspection for the logging logger tree in the Standard Library.
You can install this package with the standard pip command:
$ pip install logging_tree
While you can write programs that call this package’s tree() function and examine the hierarchy of logger objects that it finds inside of the Standard Library logging module, the simplest use of this package for debugging is to call printout() to print the loggers, filters, and handlers that your application has configured:
>>> logging.getLogger('a') >>> logging.getLogger('a.b').setLevel(logging.DEBUG) >>> logging.getLogger('x.c') >>> from logging_tree import printout >>> printout() <--"" Level WARNING | o<--"a" | Level NOTSET so inherits level WARNING | | | o<--"a.b" | Level DEBUG | o<--[x] | o<--"x.c" Level NOTSET so inherits level WARNING
The logger tree should always print successfully, no matter how complicated. A node whose [name] is in square brackets is a “place holder” that has never actually been named in a getLogger() call, but was created automatically to serve as the parent of loggers further down the tree.
There are several interfaces that logging_tree supports, depending on how much detail you need.
Prints the current logger tree, or the tree based at the given node, to the standard output.
Builds and returns the multi-line description of the current logger tree, or the tree based at the given node, as a single string with newlines inside and a newline at the end.
A generator that yields a series of lines that describe the tree based at the given node. Note that the lines are returned without newline terminators attached.
Fetch the current tree of loggers from the logging module. Returns a node, that is simply a tuple with three fields: the logger name ("" for the root logger). the logging.Logger object itself. a list of zero or more child nodes.
I welcome contributions and ideas as this package matures. You can find the bug tracker at the repository page on github. Developers can run this package’s tests with:
$ python -m unittest discover logging_tree
On older versions of Python you will instead have to install unittest2 and use its unit2 command line tool to run the tests.
- Version 1.7 - 2016 January 23
- Detect whether each logger has the correct “parent” attribute and, if not, print where its log messages are being sent instead.
- Version 1.6 - 2015 January 8
- Fixed a crash that would occur if a custom logging Formatter was missing its format string attributes.
- Version 1.5 - 2014 December 24
- Handlers now display their logging level if one has been set, and their custom logging formatter if one has been installed.
- Version 1.4 - 2014 January 8
- Thanks to a contribution from Dave Brondsema, disabled loggers are now actually marked as “Disabled” to make it less of a surprise that they fail to log anything.
- Version 1.3 - 2013 October 29
- Be explicit and display the logger level NOTSET along with the effective level inherited from the logger’s ancestors; and display the list of .filters of a custom logging handler even though it might contain custom code that ignores them.
- Version 1.2 - 2013 January 19
- Compatible with Python 3.3 thanks to @ralphbean.
- Version 1.1 - 2012 February 17
- Now compatible with 2.3 <= Python <= 3.2.
- Version 1.0 - 2012 February 13
- Can display the handler inside a MemoryHandler; entire public interface documented; 100% test coverage.
- Version 0.6 - 2012 February 10
- Added a display format for every logging.handlers class.
- Version 0.5 - 2012 February 8
- Initial release. | <urn:uuid:44d7a430-8474-433c-b543-0070a2283851> | 2.734375 | 868 | Documentation | Software Dev. | 61.467709 | 95,616,073 |
With little more than a conventional photocopier and transparency film, anyone can build a functional microfluidic chip. A local Cambridge high school physics teacher invented the process; now, thanks to a new undergraduate teaching lab at Harvard's School of Engineering and Applied Sciences (SEAS), students will be able explore microfluidics and its applications.
For years, RNA has seemed an elusive tool in nanotechnology research - easily manipulated into a variety of structures, yet susceptible to quick destruction when confronted with a commonly found enzyme. By replacing a chemical group in the macromolecule, researchers have found a way to bypass RNase and create stable three-dimensional configurations of RNA, greatly expanding the possibilities for RNA in nanotechnology.
An international research group has discovered colloidal quasi-crystals for the first time. In contrast to the quasi-crystals previously documented, which can only be produced under special laboratory conditions, they are simply structured polymers that evolve through self-assembly. Due to their structural characteristics, they will probably be used in the development of innovative devices in photonics.
Scientists from Oxford University have made a significant step towards an ultrafast quantum computer by successfully generating 10 billion bits of quantum entanglement in silicon for the first time - entanglement is the key ingredient that promises to make quantum computers far more powerful than conventional computing devices.
The quantum computers of tomorrow might use photons, or particles of light, to move around the data they need to make calculations, but photons are tricky to work with. Two new papers by researchers working at the National Institute of Standards and Technology (NIST) have brought science closer to creating reliable sources of photons for these long-heralded devices.
Electronics researchers love graphene. But creating graphene-based devices will be challenging, say researchers at the National Institute of Standards and Technology (NIST), because new measurements show that layering graphene on a substrate transforms its bustling speedway into steep hills and valleys that make it harder for electrons to get around.
The secrets behind the mysterious nano-sized electromagnetic 'hotspots' that appear on metal surfaces under a light are finally being revealed with the help of a BEAST. Researchers at the Berkeley Lab have developed a single molecule imaging technology, dubbed the Brownian Emitter Adsorption Super-resolution Technique (BEAST), that has made it possible for the first time to directly measure the electromagnetic field inside a hotspot.
University of Illinois materials scientists have developed a simple, generalizable technique to fabricate complex structures that assemble themselves. The team demonstrated that they can produce a large, complex structure - an intricate lattice - from tiny colloidal particles called triblock Janus spheres. | <urn:uuid:3b61962a-91dc-4aab-979d-7c2422448b20> | 3.453125 | 545 | Content Listing | Science & Tech. | 9.525627 | 95,616,077 |
Language Reference |
See Also Methods Properties
Provides functionality common to all JScript objects.
The optional value argument is used if you want to convert a primitive data type (number, Boolean, string, or function) into an object. If omitted, an object with no contents is created.
The Object object is contained in all other JScript objects--all of its methods and properties are available in all other objects. The methods can be redefined in objects you define, and are called by JScript at appropriate times. The toString method is an example of a frequently redefined Object method.
In this language reference, the description of each Object method includes both default and object-specific implementation information for the intrinsic JScript objects.
© 1997 by Microsoft Corporation. All rights reserved.
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What is a "Robo-Chemist" and How Does It Use Chromatography?
Nov 25 2016 Read 1937 Times
It is 65 years since the film “The Man in the White Suit” gave people a glimpse into the life of an organic chemist. The film starred Alec Guinness as a young research chemist who invents an everlasting fibre that repels dirt and never wears out. But it is the scenes filmed in the chemistry laboratories that gave many people their first insight into what it was like in a chemists’ lab.
Fast forward sixty years and the life of an organic chemist has changed enormously. Gone are the cupboards full of reagent bottles and row upon row of benches covered in variously shaped glassware. Labs are now filled with sleek fume hoods and modern high-tech instruments — and reaction vessels are no longer large round-bottomed flasks but nanotubes. Welcome to the future world of the robo-chemist.
Chemistry of the future
Organic chemists typically identify the molecule they want to create —backbone, functional groups and spatial arrangement — needed for the molecule to function. This could be a drug to target a specific abnormal molecule in the body or a catalyst to help a reaction progress more efficiently at a lower temperature. Then working backwards, they will identify the reactions and reagents needed to produce the intermediates and finally the reagents — a process known as retrosynthesis.
But looking to the future, various researchers are trying to change all that by using the latest technology — and they are looking to robo-chemist to carry out the work.
Build-a-molecule — coming to a mall near you
The ideal would be to build a machine that could fabricate a molecule automatically. Such an instrument would be a huge step forward in the pursuit of new drugs for example — but what would this machine need?
There are three main abilities such a machine would need. First it would need to know what is possible — access to all the existing chemical knowledge we have so it would know which reactions produce which products. Then it would need to map out the synthesis steps — to plan the route from reactants to products. Finally, the machine must carry out the reaction — perhaps using a robotic reactor.
Automated flow reactor
Automated flow reactors are the current gold-standard for robo-chemists. They select the most efficient conditions for producing the required products. Such an instrument might carry out hundreds of reactions in the time it takes a human to carry out just a couple of reactions — each one under slightly different reaction conditions to find the optimum catalyst, temperature, pressure or whatever other variable affects the reaction.
These instruments typically use a chromatography system to separate and analyse the reactors products on a continuous basis, helping to find the optimum variables. Sometimes the chromatography system is used to separate the products to allow analysis by other systems such as spectroscopy — a system utilising NMR is discussed in this article, Applying Benchtop NMR Spectroscopy for Reaction Monitoring.
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Android Concepts and Programming
Download Android tutorial in PDF ,free training course document under 40 pages By Kartik Sankaran.
This course will help you quickly get started with Android programming.
Table of contents
- Introduction to Android
- Simple Android Apps
- Introduction to Sensors
- Simple Sensor App
- What is Android?
- Why Linux?
- Android Version History
- How does Android manage Applications?
- How to write Applications?
- Your first Android program
- Installation Steps
- Install Android 'APIs'
- Install an IDE (Eclipse)
- Install phone's device drivers
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Scratch programming guide in PDF
Download Scratch programming tutorial by Julian Screawn, Scratch facilitate learning programming by designing and using blocks to create animation, games and videos.
A Programmer's guide to C# 5.0
Download a free Csharp training document in PDF .This pdf tutorial is for software developers who want to understand the basics of C# programming.
ADA course in PDF
Welcome to the Ada Programming tutorial in PDF, training document under 200 pages intended to beginners.
Beginner's Android Development
Beginner's Android Development Tutorial in PDF,free training course document under 26 pages to learn the basics of Mobile development.
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Download Android Tutorial in PDF ,free training document for beginner's Android Development ,file under 26 pages by (RNOC) | <urn:uuid:bad20d14-3c5e-4cc0-86ba-e3c04b1a71bf> | 2.78125 | 441 | Product Page | Software Dev. | 43.380368 | 95,616,153 |
The Genes that Drive Insect Diversity
Figure: (A) Comparison of the large adult male whole body phenotypes of GFP RNAi control animal (left) and dachshund RNAi animal (right). Control animal did not show any defect compare to wildtype animals, while dachshund RNAi showed defect phenotype in appendages including legs, antennae and mandibles. (B) Magnified image of mandibles of GFP RNAi control animal (left) and dachshund RNAi animal (right). RNAi of dachshund gene affected both of mandible size and shape. Credit: Hiroki Gotoh
Insects are a biological success story with their high abundance, dominating biodiversity, and almost worldwide distribution. Their evolutionary prowess in part reflects their ability to diversify and fill a variety of ecological niches. One means of doing this is developing a range of mouthparts that enables different foodstuffs to be consumed. Mouthparts can be highly modified, as in the straw-like maxillae of butterflies, or exceptionally enlarged, as in the mandibles of stag beetles that are used for fighting rather than feeding. However, the molecular mechanisms underlying mandible enlargement have been poorly understood. Collaborative Japan-US research coordinated by Nagoya University has now shed light on the genetic control of stag beetle mandible development. The study was published in Developmental Biology.
The development of appendages, such as limbs and mouthparts, at different distances from the body wall (proximal through medial to distal) is controlled by a series of genes highly conserved among all insects. The researchers used a molecular silencing technique to sequentially knockdown the expression of seven of these genes to investigate their function in the development and enlargement of stag beetle mandibles.
The dachshund (dac) gene, which controls regulation of the middle region of appendages in Drosophila and many other insects, had the greatest effect on mandible development of all seven genes analyzed.
"Knockdown of dac greatly reduced mandible size in male but not female stag beetles, and affected mandible morphology in both sexes," corresponding author Hiroki Gotoh says. "Knocked-down animals did not develop the serrated teeth normally seen in all males, and also lacked the inner teeth characteristic of large males."
Genes aristaless (al) and homothorax (hth) were also shown to have important roles in the development of inner teeth. However, knockdown of the Distal-less (Dll)gene, which is functional in distal regions, had no effect on mandible development. This supports previous knowledge that insects lost their most distal mandible regions early in evolution.
Male-specific mandible enlargement in stag beetles is known to be regulated by juvenile hormone, such that larger males have disproportionately larger mandibles.
"We observed a size-specific link with the functions of dac, al, and hth in the knockdown studies," Gotoh adds. "This suggests that these genes control their function using a size-dependent factor - most likely juvenile hormone."
Genetic silencing also revealed that the seven genes largely controlled stag beetle leg development in a manner highly conserved with that of other insects, but that their roles in antennal formation were more diverse. These conserved developmental functions of some genes but varied roles of others are likely to have contributed to the evolution of mouthparts in different insect species.
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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.
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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 | <urn:uuid:eebc132f-f67d-4339-8534-52649eb37e81> | 3.59375 | 901 | Knowledge Article | Science & Tech. | 16.497945 | 95,616,156 |
Prime numbers are a mathematical concept that describes positive whole numbers that can only be divided evenly by two other whole numbers (or factors). For example, the number 2 is a prime number, because it can only be divided by itself and 1. Another prime number is 7. Prime numbers are important in many branches of mathematics, including cryptography, the making and breaking of codes.
The Hard Way
Write down a number you wish to test to see if it is prime.
Find the square root of the number you wish to test using a computer or calculator. If the square root is a whole number, then you know the number is not prime and can give up on it. Otherwise, the number could still be prime, so go on to step 3.
Divide the number you are testing, one by one, by each number between 2 and the square root of the tested number. One of the traits of numbers is that, if they have a factor pair, one of the factors must be equal to or less than the square root. So, if you test all the numbers up to the square root, you can rest assured that the number is prime. For example, the square root of 23 is around 4.8, so you would test 23 to see if it can be divided by 2, 3 or 4. It cannot be, so 23 is prime.
This solves the problem, but it is very labor intensive, especially when you wish to check a lot of numbers at once. For this reason, an ancient Greek mathematician created a method to make it easier.
Using the Sieve of Eratosthenes
Decide on a range of numbers you wish to test and lay them out on square grid. Just like in the first method, you will need to find the square root to decide how wide to make the grid: your work will be shorter if the grid is as close to a perfect square as is possible.
For example, to test all the numbers from 1 to 25 for primes, make the following 5x5 grid:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Cross out 1 with an X, because 1 is never considered prime by mathematicians for technical reasons.
Circle 2, because 2 is a prime. Now, cross out with an X every number which can be evenly divided by 2. So, cross out 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24. These numbers cannot be prime because they can be divided by a number other than 1 and themselves; namely 2.
Circle 3, and repeat the previous step, crossing out all the multiples of 3 which aren't already crossed out.
Skip 4, because it is crossed out and circle the next number which has not been crossed out (5). It is a prime number. Continue until all the numbers on your chart are either circled or crossed out. If you made your chart perfectly square, that should occur about the time you finish the first row. | <urn:uuid:4bb8b69b-831b-44b5-8d4d-ce845c54583f> | 3.859375 | 630 | Tutorial | Science & Tech. | 75.391831 | 95,616,166 |
Globular clusters have long been used to test theories of stellar evolution, stellar dynamics, and galaxy formation. In recent years, these old clusters have emerged as fertile grounds to search for black holes and understand their formation. “Intermediate-mass” black holes have been proposed to lurk in their centres and could represent seeds from which super-massive black holes grow in the early universe. Dynamical formation of stellar-mass black hole binaries in the dense cores of globular clusters has also been suggested as a main formation channel for the sources of gravitational waves recently detected by the LIGO experiment. I will give an overview of the recent successes (and failures) of astronomers’ exciting hunt for black holes in globular clusters.
Bio: Vincent Hénault-Brunet recently joined NRC Herzberg as a Plaskett Fellow. He was born in Montreal, where he completed his BSc in physics from McGill and MSc in astrophysics from Université de Montréal. He then obtained his PhD from the Institute for Astronomy at the University of Edinburgh (UK), and was a research fellow at the University of Surrey (UK) and Radboud University (Netherlands) before moving to Victoria. His research focuses on stellar populations and globular clusters, in particular on the dynamics of stars in these systems.
As the spring and summer approaches, planning is underway for our annual season of outreach events. The first event of the season is Astronomy Day on Saturday, April 21 at the Royal BC Museum. We will require volunteers to help with this event including people for the information table, people to do a show and tell with telescopes and their astrophotography, and some solar viewing as well if the skies cooperate. If you have not already been contacted and wish to help out, please contact Ken (firstname.lastname@example.org) to put your name on the list as an outreach volunteer.
We will be holding another season of Star Parties at the Dominion Astrophysical Observatory on Saturday evenings. The first of these evenings will be on Astronomy Day. The season will continue until Saturday, September 1 for a total of twenty evenings. Planning is underway for some special evenings including Saturday, May 5 to coincide with the 100th anniversary of first light of the Plaskett Telescope that was on May 6, 1918. Again we will need people to be on hand to direct the visitors, provide views of the sky with telescopes, and other duties. We have a contact list of volunteers but if you are not on the list already and would like to be added please contact Chris (email@example.com).
The annual general meeting of the Canadian Astronomical Society (CASCA) is taking place in Victoria this year. The conference title is A New Century for Canadian Astrophysics and it will be at the convention centre from May 22 to 26. Through a special arrangement with the organizing committee, members of RASC may register to attend. The options for RASC members are a one day rate or four day rate; the early bird rates are in effect until April 6. Complete details about the meeting, including a list of invited, centenary, and education and public outreach speakers, an outline of the graduate student workshop program, and special events, can be found on the CASCA 2018 website. One of the speakers, former RASC president R. Peter Broughton, is the author of new book about John Stanley Plaskett founder of the Dominion Astrophysical Observatory. Entitled Northern Star J.S. Plaskett, it is now available from the RASC store.
Wednesday February 14th 2017 at 7:30 PM Room A104, Bob Wright Centre.
During the past two decades, the standard model of the cosmology ΛCDM has commonly been accepted by the astrophysical community and successfully reproduced and even predicted many observational effects. I will discuss about one of the principal components of this model: dark matter and I will describe why we need it and what are the current hypotheses of its nature.
Bio: Guillaume Thomas is a new postdoctoral NRC fellow who joined Herzberg Astronomy and Astrophysics in October. He was born in Epinal France and obtained his Master and PhD at the Strasbourg Observatory. Thomas is interested in the formation and the dynamical evolution of spiral galaxies. He is also interested in exploring alternative theories to the model ΛCDM. You can follow him on Twitter at @Thomas_gft.
I find it fascinating that we have developed a sensationalized vocabulary about naturally occurring events. Perhaps it is the result of reality television becoming so prevalent that everything must be a challenge, a contest, the best, the brightest, the most shocking, etc. Having the recent lunar eclipse labelled with 3 different descriptors, super moon, blue moon, and blood moon, made for some interesting headlines. Are these events really deserving of these labels?
The distance between the moon and the earth does change throughout the month due to the moon’s elliptical orbit. For a viewer on earth, the apparent change in the moon’s diameter between apogee and perigee is about 13%. That does make a full moon around the perigee appear larger thus potentially brighter. But do most of us really notice without being told? Probably not. As the earth has a greatly varying atmosphere, which has a significant influence on light transmission, the amount of light from a full moon is not a reliable indicator. How many of us can recognize that a full moon is larger, or smaller, than the previous time we saw it? Photographs will show a difference but most of us do not have that sort of visual memory. Is a moon that appears to be 13% larger than at its smallest apparent diameter a difference worthy of being called a super moon? I lean toward describing it as a full moon near the perigee.
According to sources I have found, the term blue moon, when used to count full moons in a certain time period, was originally used for seasons. Most seasons have three full moons but every tenth season or so has a fourth full moon. The blue moon was the label given to the third full moon of a season with four full moons. Along the way, blue moon has become an accepted expression for the second full moon in a single calendar month. Is having an extra full moon in a month or a season, both of which are arbitrary, human-designated periods of time, significant? Why not just refer to it as the second full moon of January? By the way, March 2018 also has 2 full moons so we will have a second blue moon this year.
The term blood moon is used to describe the red-coloured moon that we see during a lunar eclipse. During the eclipse, the sun’s light is blocked from reaching the moon’s surface directly. The earth’s atmosphere scatters light, particularly in the blue-violet end of the spectrum. This means that light that has passed through the earth’s atmosphere and travels on toward the moon is primarily at the red end of the spectrum. Some of this light will end up reaching the moon’s surface and the result is a moon illuminated by light that is strongly in the red wavelengths. I’m not sure why we just don’t call it a red moon.
So, although we did not see much of the eclipse here, I hope those who did enjoyed seeing the large, red moon caused by the lunar eclipse during the second full moon of January 2018 when the moon was close to perigee. Ok, maybe saying the super blue blood moon sounds better!
On Wednesday, January 31st, weather willing, we will be able to view a total eclipse of the Moon. The Moon will move into full eclipse in the early hours of the morning and will be in partial phase in the western sky as the Sun rises. The Total Lunar Eclipse will develop over the course of about 3 hours. It’s a perfect opportunity to capture some snapshots of the event. Read further to find out what happens during the eclipse and how to capture it photographically.
E C L I P S E T I M E L I N E
Moon below the horizon
Moon’s eastern limb enters the penumbra
2:51 am PST
Partial eclipse begins – 1st Contact
Moon’s eastern limb enters the umbra
3:48 am PST
Total eclipse starts – 2nd Contact
Moon entirely in the umbra; deep orange red
4:52 am PST
5:30 am PST
Total eclipse ends – 3rd Contact
6:08 am PST
Partial eclipse ends – 4th Contact
Moon’s western limb leaves the umbra
7:11 am PST
7:48 am PST – approximate
Moon leaves the penumbra
8:09 am PST
A total lunar eclipse occurs when the Earth comes between the Sun and the Moon. During a lunar eclipse the Moon’s position traverses the Earth’s shadow. The Moon’s first contact with the Earth’s shadow is at the outer band of the shadow called the penumbra. The light falling on the Moon is progressively blocked until at the moment of total eclipse the Moon is completely in the darkest central area of the Earth’s shadow called the umbra. At the point of total eclipse the process starts to reverse itself until the Moon is totally out of the Earth’s shadow.
limb – the outer edge of the Moon
penumbra – the outer band of the Earth’s shadow
umbra – the darker central area of the Earth’s shadow
partial eclipse – the Moon is positioned within the penumbra
total eclipse – the Moon is positioned totally within the umbra
Above Eclipse times are for Pacific Standard Time (PST) for the west coast of North America, and are calculated from UT as presented in the Observers Handbook 2018, pages 126-27.
What do you need?
Everything from your eyes, binoculars and telescope are suitable. Bear in mind this is a long process and at this time of year dress warmly and bring a chair if you want to be comfortable.
Find yourself a location that has a clear horizon view of the west especially if you wish to view during the late stages.
Keep a log of what you see and note the time. Pay attention to how much of the light on the moon is obscured and if there are any colouration changes. During the total eclipse the Moon will take on a deep orange-red colour. The colour of the Moon is a function of contaminants in the atmosphere and varies from year to year.
Any camera with the capability of setting shutter speeds and aperture settings manually will do fine. The ability to use interchangeable lenses will be an advantage for more detailed images of the Moon. For the darker parts of the eclipse, eg. totality you should use a tripod support for best results. If you have access to a telescope you can try capturing the event using prime focus techniques through the telescope optics.
Today’s digital cameras are very sensitive to light reflected by the Moon. Use ISO 400 to ISO 800 and a long telephoto lens or zoom setting. Smartphones and point-and-shoot digital cameras will not produce rewarding photos of the eclipsed Moon, but can be useful for taking panoramic shots of your surroundings which include the eclipsed Moon.
The simplest eclipse pictures can be taken with manual settings on your camera and a normal lens, preferably supported by a tripod. For best results use a cable release to minimize vibration. Images taken in this fashion result in a small lunar image. This is why it is preferable to use a telephoto lens to photograph the Moon. For a 35mm camera try a 200mm lens or something close to this, even better a 500mm lens or higher. You may also use teleconvertors to increase magnification, these typically come in 1.4x and 2x strengths. Their downside is they reduce the effective aperture of your optical system. A 1.4x teleconvertor will decrease your effective exposure by 1 stop, a 2x teleconvertor will decrease your effective exposure by 2 stops. Work out your effective aperture of your optical system ahead of time so you don’t have to think about it on the night of the eclipse.
Effective Focal Length
with 2x teleconvertor
with 2x teleconvertor
To achieve any higher magnification than what is stated above you will have to use a telescope at prime focus. For this your manual camera does need to have the capability of using interchangeable lenses. For prime focus you will use the telescope optics as your interchangeable lens. To attach your camera to your telescope you will need two things a T-adapter that fits your camera and a telescope camera adapter that fits your telescope. The telescope camera adapter is designed to fit in the focusing tube of your telescope and is threaded to accept the T-adapter of your camera. With the magnification involved with telescopic optics it is likely that you will need to use a tracking mount. Preferably the mount should be able to track at lunar speed as opposed to sidereal but if the shutter speeds chosen are shorter than 1 or 2 minutes this is not critical.
Exposure times are the next consideration. The following exposure times are based on a medium speed film and an effective aperture that would be common with a long telephoto and teleconverter combination. Exposures may vary with your equipment based on ISO speed of film used and effective aperture. The Danjon Lunar Eclipse Luminosity Scale has been included to provide better guesstimates for totality.
Exposure Times: based on ISO 400
1/250 second at f/16
1/125 second at f/16 see note 1.
2 seconds at f/16 see note 2.
*see table below
L = 4 :
8 seconds at f16
L = 3:
30 seconds at f16
L = 2:
2 minutes at f16
L = 1:
8 minutes at f16
2 seconds at f/16 see note 2.
1/125 second at f/16 see note 1.
* Danjon Lunar Eclipse Luminosity Scale
L = 1
dark eclipse; lunar surface details distinguishable only with difficultly
L = 2
deep red or rust coloured eclipse; central part of the umbra dark but outer rim relatively bright
L = 3
brick-red eclipse; usually with a brighter (frequently yellow) rim to the umbra
L = 4
very bright copper-red or orange eclipse, with a bluish, very bright umbral rim
Note 1. 1st and 4th contact times given for the partial phases are biased for the light part of the Moon. Remember you are dealing with vastly different exposures between the light and dark parts of the Moon during eclipse. The bias of about 1 stop minus avoids overexposure of the dominant bright area of the Moon.
Note 2. 2nd and 3rd contact times given for the partial phases are biased for the dark part of the Moon. The bias of about 1 stop plus is a good strategy for negative film not quite so good for slides and digital capture given they don’t tolerate overexposure well.
The exposure times are only recommendations. Remember the cardinal rule about photography … bracket. Always try exposures plus and minus your chosen exposure. This gives you a better chance at getting usable results. Let’s all hope for clear weather. If you have any questions please send email to David Lee at firstname.lastname@example.org.
David Lee – original image and text
Joe Carr – updated for 2018
Brenda Stuart – illustrations
RASC Victoria members used the Bob Wright Centre at the University of Victoria for a nation-wide celebration of RASC astronomy in Canada for the last 150 years, from 3-5pm on Saturday, January 27th. We will were joined by astronomy teachers and students from University of Victoria, Camosun College, and Victoria High School. Tours of the 32″ telescope and observing the Sun through solar telescopes was happening outside. Members participated in a series of Youtube “webisodes” from RASC Centres across Canada.
As a follow-up to last January’s report, it is time to report back about my progress with my astronomy resolutions of 2017. One of my goals was to learn more and I did achieve that. One area I know little about is astrophotography. To learn more, I purchased a CCD camera in March and have been learning to use it. Primarily, I have done this in daylight hours so I could see what I was doing. I have tried photographing distant objects, typically trees, so I can work on achieving focus. I chose a monochrome camera so I also bought a set of filters and a filter wheel so I have been figuring out how to include those in what I have been doing. As there are a number of parts to all this, i.e., camera, filter wheel, software, etc. there is a lot to learn. I have taken small steps so far but I am getting much more proficient at the tasks I have practised.
Another goal was to spend more time observing. I did spend more time looking through a telescope in 2017 which was good and I’m getting much better at finding objects. One thing to work on this year is getting out on more evenings when the sky is clear. It is still too easy to turn on the television or sit in front of the computer. So this year, my goals are to keep learning and do even more observing.
2018 is looking to be another active year for the Victoria Centre. As introduced in my December report, the first event of 2018 will be the launch of the RASC sesquicentennial on Saturday, January 27. We will be looking for helpers for this event in the coming weeks and I hope that many of you can attend.
We are planning to hold Astronomy Day in April again this year as well as Summer Star Parties at the DAO. These are great opportunities to get involved and more information will be provided as plans are made. Make sure you visit our website to keep up to date about the activities of our Centre.
Quasars are the brightest objects in our Universe. A quasar is a rotating disk as big as our solar system and hotter than the Sun, formed when matter spirals into a supermassive black hole at the centre of a galaxy. I will discuss these fascinating objects and how they tap the strong gravity of black holes.
Bio: Patrick Hall is an astronomer and Professor at York University. Born in California to Canadian parents, he was an undergraduate at U. C. Berkeley, a graduate student at U. Arizona, and a postdoc at U. Toronto, Princeton, and the Universidad Catolica de Chile. He divides his work time between research on quasars (and any object with a sufficiently odd spectrum), teaching astrophysics, and outreach. You can follow him on Twitter at @patrickbhall
by Michel Michaud, RASC Victoria Centre Observing Co-chair & Librarian
The Lunar X is a claire-obscure effect in which light and shadow creates the appearance of a letter “X” on the rim of the Blanchinus, La Caille and Purbach craters. The X is visible only for a few hours before the first quarter slightly below the lunar terminator. Near the X, the lunar V is also visible, formed by Ukert crater and several other small craters.
If you never had the chance to view the Lunar X, also known as the Werner X, there are several time this year that feature could be visible from Victoria. The time predict the beginning of the event and all in LOCAL TIME.
23 January 2018, 2042 (8:42 pm) – Tuesday evening event
23 March 2018, 2357 (11:57 pm) – Friday evening event
21 May 2018, 0002 (12:02 am) – Monday evening event
19 July 2018, 2314 (11:14 pm) – Thursday evening event
16 September 2018, 2332 (11:32 pm) – Sunday evening event
14 November 2018, 0059 (12:59 am) – Wednesday evening event | <urn:uuid:0eb5762b-e656-4046-9c76-bbd56edeb771> | 2.59375 | 4,208 | Content Listing | Science & Tech. | 54.224893 | 95,616,167 |
the Kansas State Physics Education Research Group,
Dean A. Zollman, and
N. Sanjay Rebello
This resource illustrates the construction of scattering state wavefunctions in one dimension for a piece-wise constant potential. A barrier or well can be created from two potential steps, that can be of different heights. Students are then asked to plot the electron wavefunction in this potential by changing its nature, amplitude, wavelength, and phase in the three different potential regions. A correct solution requires students to work through the problem using the parameters given.
Kansas State Physics Education Research Group, Zollman, D., & Rebello, N. (n.d.). Wave Function Sketcher. Retrieved July 16, 2018, from https://web.phys.ksu.edu/vqm/software/online/vqm/html/wfsketcher.html
%Q Kansas State Physics Education Research Group %A Dean Zollman %A N. Sanjay Rebello %T Wave Function Sketcher %U https://web.phys.ksu.edu/vqm/software/online/vqm/html/wfsketcher.html %O application/shockwave
%0 Electronic Source %A Kansas State Physics Education Research Group, %A Zollman, Dean %A Rebello, N. Sanjay %T Wave Function Sketcher %V 2018 %N 16 July 2018 %9 application/shockwave %U https://web.phys.ksu.edu/vqm/software/online/vqm/html/wfsketcher.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:3afa94d0-bf67-4625-80a0-f94199f90085> | 3.484375 | 378 | Content Listing | Science & Tech. | 57.07485 | 95,616,200 |
about this item
From one of our most eminent theoretical astrophysicists and an award-winning writer, a fascinating, firsthand history of the scientific pursuit to detect gravitational waves: the holy grail of modern cosmology, the soundtrack of the universe.In 1916, Einstein became the first to predict the existence of gravitational waves: sounds without a material medium generated by the unfathomably energy-producing collision of black holes. Now Janna Levin, herself an astrophysicist, recounts the story of the search over the last fifty years for these elusive waves--a quest that has culminated in the creation of the most expensive project ever funded by the National Science Foundation ($1 billion-plus). She makes clear how the waves are created in the cosmic collision of black holes, and why the waves can never be detected by telescope. And, most revealingly, she delves into the lives and fates of the four scientists currently engaged in--and obsessed with--discerning this soundtrack of the universe's history. Levin's account of the surprises, disappointments, achievements, and risks of this unfolding story provides us with a uniquely compelling and intimate portrait of the people and processes of modern science.
Number of Pages: 241
Sub-Genre: Gravity, Waves + Wave Mechanics, Astrophysics + Space Science
Publisher: Random House Inc
Author: Janna Levin
Street Date: March 29, 2016
Item Number (DPCI): 248-13-0097 | <urn:uuid:e9e8a35b-6da2-4d14-9cef-eb6b9f68e5b8> | 2.734375 | 297 | Product Page | Science & Tech. | 16.248466 | 95,616,205 |
Ocean fertilisation is a proposed form of geo-engineering that involves the introduction of iron particles to the upper ocean to stimulate a phytoplankton bloom.
In theory, the phytoplankton will then absorb CO2 before dying and sinking to the bottom of the ocean where the carbon will be sequestered.
An experiment in early 2009 in the Southern Ocean dampened hopes for widespread uptake of the technology after crustacean zooplankton fed on the bloom before it died and reintroduced the extracted CO2 into the atmosphere.
However, some scientists maintain that ocean fertilisation could prove a cost effective means of reducing concentrations of CO2 in the atmosphere. Environmental groups counter that large scale ocean fertilisation projects could have unexpected consequences on maritime food chains.
All single-use plastic straws will be removed from UK and Ireland stores by October as part of flatpack giant's push to eliminate single-use plastics across its operations by 2020
Policy Exchange report argues a unified carbon tax in the UK with revenues paid as a dividend to taxpayers could cut emissions and tackle carbon leakage
DB Cargo UK, the UK's largest freight provider, now sources 100 per cent green power for all its rail sites and offices under new deal with SSE
Leaders put climate at centre of relationship, push for agreement on the Paris deal rulebook and reject Trump's efforts to undermine global cooperation | <urn:uuid:653cdee6-1b56-43fb-b9f4-cefe110fcfd7> | 3.390625 | 282 | Knowledge Article | Science & Tech. | 8.042448 | 95,616,210 |
Plot some representative velocity profiles for the purely oscillatory flow of a Newtonian fluid in a long, rigid, straight pipe at various phases of the flow (3-4).
For these plots, use the values of constants given below:
Velocity (u): 105 cm/s
Diamter (d): 2.23 cm
Kinematic viscosity (nu): 0.035 cm^2/s
Reynolds Number: 6690
Generate data for the plots simply by evaluating the solution at many radii, showing the evaluation of algebra. Note any characteristic shapes. How do they change as alpha changes?
(For analytic solution of this problem, see the book by Schlichting and see also Gerrard, J. Fluid Mech., 1971, 46)© BrainMass Inc. brainmass.com July 19, 2018, 3:29 am ad1c9bdddf
Hi, your problem has a solution that can be very simple. This solution is call the Blasius 1/7 power law (see page 170 - 171 of Bennet - Myers, Momentum, Heat and Mass Transfer, edition TMH of Tata Mc Graw Hill Publishing Company).
That law is u/umax ...
This solution explains in 170 words how the Blasius 1/7 power law can be used to find the velocity of flow in a system. Calculations for boundary thickness are also provided to explain how delta can be computed for each length of conduction. | <urn:uuid:efdedf3c-0b70-4c9a-bbba-11a53c801d70> | 3.453125 | 307 | Q&A Forum | Science & Tech. | 70.216765 | 95,616,230 |
The following questions and problems are from "Physics 7th edition by Cutnell and Johnson, Chapter 4" which includes the concepts like Newton's laws of motion, the vector nature of Newton's second law of motion, type of forces (gravitational, normal, static and kinetic/frictional forces, tension force), equilibrium and non-equilibrium applications of Newton's laws of motion.
Please consider significant figures and if possible, draw visual graphics.
1. Why do you lunge forward when your car suddenly comes to a halt? Why are you pressed backward against the seat when your car rapidly accelerates? In your explanation, refer to the most appropriate one of Newton's three laws of motion.
2. The net external force acting on an object is zero. It is possible for the object to be traveling with a velocity that is not zero? If your answer is yes, state whether any conditions must be placed on the magnitude and direction of the velocity. If your answer is no, provide the reason for your answer.
3. Is a net force being applied to an object when the object is moving downward (a) with a constant acceleration of 9.80 m/s^2 and (b) with a constant velocity of 9.80 m/s? Explain.
4. A father and his seven year old daughter are facing each other on the ice skates. With their hands, they push off against one another.
(a) Compare the magnitudes of the pushing forces that they experience.
(b) Which one, if either, experiences the larger acceleration? Account for your answer.
5. According to Newton's third law, when you push on an object, the object pushes you back on you with an oppositely directed force of equal magnitude. If the object is a massive crate resting on the floor, it would probably not move. Some people think that the reason the crate does not move is that the two oppositely directed pushing forces cancel. Explain why this logic is faulty and why the crate does not move.
6. When a body is moved from the sea level to the top of the mountain, what changes - the body's mass, its weight, or both? Explain.
7. The force of air resistance acts to oppose the motion of an object moving through the air. A ball is thrown upward and eventually returns to the ground.
(a) As the ball moves upward, is the net force that acts on the ball greater than, less than, or equal to its weight? Justify your answer.
(b) Repeat part (a) for the downward motion of the ball.
8. A person has a choice of either pushing or pulling a sled at a constant velocity. Friction is present. If the angle θ is the same in both cases, does it require less force to push or to pull? Account your answer.
9. Suppose that the coefficients of static and kinetic friction have values such that µs = 1.4 µk for a crate in contact with a cement floor. Does this mean that the magnitude of the static frictional force acting on the crate at rest would always be 1.4 times the magnitude of the kinetic frictional force acting on the moving crate? Give your reasoning.
10. Can an object ever be in equilibrium if the object is acted on by only (a) a single nonzero force, (b) two forces that point in mutually perpendicular directions, and (c) two forces that point in directions that are not perpendicular? Account for your answer.
11. During the final stages of descent, a sky diver with an open parachute approaches the ground with a constant velocity. The wind does not blow him from side to side. Is the sky diver in equilibrium and, if so, what forces are responsible for the equilibrium?
12. A weight hangs from a ring at the middle of a rope. Can the person who is pulling on the right end of the rope ever make the rope perfectly horizontal? Explain your answer in terms of the forces that act on the ring.
(Newton's Law of Motion)
1. A boat has a mass of 6800 kg. Its engines generate a drive force of 4100 N, due west, while the wind exerts a force of 800 N, due east, and the water exerts a resistive force of 1200 N due east. What is the magnitude and direction of the boat's acceleration?
2. A 15-g bullet is fired from a rifle. It takes 2.50 x 10^-3 s for the bullet to travel the length of the barrel with a speed of 715 m/s. assuming that the acceleration of the bullet is constant, find the average net force exerted on the bullet.
(The Vector Nature of Newton's Second Law of Motion and Newton's Third Law):
3. A 350-kg sailboat has an acceleration of 0.62 m/s^2 at an angle of 64 degrees north of east. Find the magnitude and the direction of the net force that acts on the sailboat.
4. When a parachute opens, the air exerts a large drag force on it. This upward force is initially greater than the weight of the sky diver and, thus, slows him down. Suppose the weight of the sky diver is 915 N and the drag force has a magnitude of 1027 N. The mass of the sky diver is 93.4 kg. What are the magnitude and direction of his acceleration?
5. A rock of mass 45 kg accidentally breaks loose from the edge of a cliff and falls straight down. The magnitude of the air resistance that opposes its downward motion is 18 N. What is the magnitude of the acceleration of the rock?
6. Synchronous communications satellites are placed in a circular orbit that is 3.59 x 10^7 m above the surface of the earth. What is the magnitude of the acceleration due to gravity at this distance?
7. Mars has a mass of 6.46 x 10^23 kg and a radius of 3.39 x 10^6 m.
(a) What is the acceleration due to gravity on Mars?
(b) How much would a 65kg person weigh on this planet?
(The Normal Force, Static and kinetic frictional Force)
8. A block whose weight is 45.0 N rests on a horizontal table. A horizontal force of 36.0 N is applied to the block. The coefficients of static and kinetic friction are 0.650 and 0.420, respectively. Will the block move under the influence of the force, and if so, what will be the block's acceleration? Explain your reasoning.
9. A 60.0 kg crate rests on a level floor at a shipping dock. The coefficients of static and kinetic friction are 0.760 and 0.410, respectively. What horizontal pushing force is required to (a) just start the crate moving and (b) slide the crate across the dock at a constant speed?
(The tension Force, Equilibrium Applications of Newton's Law of Motion)
10. A stuntman is being pulled along a rough road at a constant velocity by a cable attached to a moving truck. The cable is parallel to the ground. The mass of the stuntman is 109 kg, and the coefficient of kinetic friction between the road and him is 0.870. Find the tension in the cable.
11. A 1.40-kg bottle of vintage wine is lying horizontally in the rack. The two surfaces on which the bottle rests are 90.0 degrees apart, and the right surface makes an angle of 45.0 degrees with respect to the ground. Each surface exerts a force on the bottle that is perpendicular to the surface. What is the magnitude of each of these forces?
(Non-equilibrium Applications of Newton's Law of Motion)
12. The two blocks are connected via a pulley. The weight of the block on the table is 422 N and that of the hanging block is 185 N. Ignoring the frictional effects and assuming the pulley to be massless, find (a) the acceleration of the two blocks and (b) the tension of the cord.© BrainMass Inc. brainmass.com July 19, 2018, 3:52 am ad1c9bdddf
This solution provides steps necessary to answer each question regarding Newton's Law of Motions. | <urn:uuid:023ee078-3aca-4778-a0c2-b0c02ac9ed3e> | 3.734375 | 1,724 | Q&A Forum | Science & Tech. | 76.804448 | 95,616,231 |
- Open Access
Photosynthetic UV stress tolerance of the Antarctic snow alga Chlorella sp. modified by enhanced temperature?
© Rivas et al. 2016
Received: 16 November 2015
Accepted: 9 February 2016
Published: 31 March 2016
Photosynthetic characteristics and the effect of UV radiation and elevated temperature measured were studied in Chlorella sp. isolated from a snow microalgal community at King George Island, Maritime Antarctica through the chlorophyll florescence (rapid light curves and maximum quantum yield, respectively). The environmental context was monitored through measurements of spectral depth profiles of solar radiation (down to 40 cm) in the snowpack as well as a through continuous recording of temperature and PAR using dataloggers located at different depths (0–30 cm) within the snow column.
The photochemistry of Chlorella sp. was affected by UV radiation in a 12-h laboratory exposure under all studied temperatures (5, 10, 15, 20 °C): the algae exposed to PAR + UV-A radiation were inhibited by 5.8 % whilst PAR + UV-A + UV-B radiation decreased Fv/Fm by 15.8 %. In both treatments the 12-h recovery after UV exposure was almost complete (80–100 %). Electron transport based P-I curve parameters maximal electron transport rate (ETRmax), photosynthetic efficiency (α) and the saturating irradiance (Ek) no varied in response to different temperatures.
Results revealed that Chlorella sp. not only shows high photosynthetic efficiency at ambient conditions, but also exhibits tolerance to solar radiation under higher temperatures and possessing a capacity for recovery after inhibition of photosynthesis by UV radiation.
The Antarctic cryosphere represents a hostile habitat for life, characterized by extreme temperature conditions varying abruptly between freezing and melting points, high levels of solar radiation, especially harmful wavelengths of ultraviolet (UV) radiation, nutrient limitation, changes in pH and osmotic stress [1, 2]. The physico-chemical properties of melting snow allow psychrophilic algae to grow in liquid interstices, where the temperature is just above the freezing point [3–5]. In polar snowfields, the biomass of snow algae can become very important and due to their capacity to fix and store carbon they play a key role as primary producers in the biogeochemical cycles in Arctic and Antarctic regions . In coastal areas of West Antarctic Peninsula and adjacent islands, an eco-region denominated Maritime Antarctica, processes occurring in glacier and snow ecosystems are closely interrelated with those of the marine realm. Melting of massive snow/ice accumulations and consequent run-off have strong impact on the physical and biological processes of near-shore pelagic and benthic communities [7, 8].
Due to that snow algae inhabit ecosystems highly sensitive and responsive to shifts in environmental conditions (e.g. temperature, light and precipitation), they can be regarded as excellent model organisms to examine the impact of climate change. Warming in several regions has been related with lower precipitation as snow, earlier runoff and hence, a shortened period of snow permanence [9, 10]. Under these scenarios, snow algae and their associated microbial community have to adapt to new regimes of melting and freezing , underlining not well-understood physiological adaptations.
Unlike alpine and other continental snowfields, coastal snow packs located in Maritime Antarctica are tentatively eutrophic environments, mostly due to the presence of seabird and mammal colonies . Thus, for this habitat, light and temperature remain as the major stressors for snow algae. However, the question how these factors, alone or in combination, impact snow communities in Antarctic coastal snowfields has been poorly addressed. Data from alpine snow algae indicate that light, especially due to scattering, can be elevated and thus, algae have to cope with irradiation stress, caused by Photosynthetically Active Radiation (PAR) and Ultraviolet (UV) in conditions of low temperatures. Especially during the sensitive motile green phase in their life cycle, microalgae are sensitive excess PAR and UV , which affect different molecules and processes (e.g. DNA, photosynthetic apparatus, lipid membranes, etc.; reviewed by ) and also cell motility . However, some snow algae downregulate their photochemical processes via a series of dissipative mechanisms such as the violaxanthin cycle, synthesis and accumulation of astaxanthin, turnover of D1 proteins, antenna quenching, cold induced transcripts and cold-adapted proteins, etc. which operate at temperatures close to 0 °C [12, 16, 17]. The question whether these mechanisms operate efficiently at higher temperatures remains open.
Chlorella is a unicellular green alga, which has a single chloroplast, rigid cell wall and lacks flagella . The genus is globally distributed including the Antarctic [19, 20]. In general this microalga inhabits soils and other ice-free environments, however, can also be found in snow packs during the summer melting season . Teoh et al. analysed the growth rates, biochemical composition and profile of fatty acids of six Antarctic strains, of which algae of the class Trebouxiophyceae, including Chlorella, presented the greatest growth rates at enhanced temperature of 20 °C. Significant alterations in the morphology and activity of the chloroplasts in response to enhanced UV-B radiation have been reported for this genus . Due to that gradients in solar radiation along the snowpack can impose not only considerable stress as a consequence of detrimental and photoinhibitory levels of UV radiation and PAR, but also can result in light limitation for photosynthesis at lower snow depths, one could argue that an acclimation process or physiological flexibility are important to ensure primary production. Up to now, most of the studies on snow algal photobiology have been conducted in ubiquitous flagellate green algal genera such as Chlamydomonas, or Chloromonas, which show an ability to actively migrate along the snow pack column and thus “regulate” their light environment [3, 24–26]. In a recent study was demonstrated that Antarctic strains of Chlorella are more sensitive to UV radiation under elevated temperature than their counterparts from temperate or tropical regions . Thus, in the present study the question whether photosynthetic characteristics of non-motile Chlorella sp. isolated from snow fields in Maritime Antarctica (King George Island) match the light and temperature conditions prevailing at different snow depths was examined. Moreover, the ability of Chlorella to endure environmental stress was assessed in a series of controlled exposures to UV radiation and elevated temperature. The prediction that elevated temperatures will enhance the detrimental effects of UV radiation was tested.
Collection and isolation of snow microalgae
Measurement of solar radiation and temperature in the snowpack
In situ spectral irradiance was measured during a sunny day (February 13, 2015 at noon) using an underwater hyperspectral radiometer (RAMSES-ACC2-UV–Vis, TriOs Optical Sensors, Rastede, Germany) through the snow column down to a depth of 40 cm (8 and 19 measurements per depth). According to the President Eduardo Frei Montalva Metereological Station’s records, this day had 10 % cloud cover, and moderate breeze from the Northwest at 3 m/s. At the same time, a set of HOBO UA-002-64 dataloggers (Onset Computer Corporation, Bourne, MA, USA) was programmed to record temperature and solar irradiance (PAR) at 0, 10, 20 and 30 cm depth in the snow column every 5 min for 15 days during the study period.
Exposures to temperature and UV radiation
Samples from Chlorella sp. clonal culture (3500 cell/ml, exponential growth phase) were put in cell culture plates without aeration and exposed to PAR, PAR + UV-A and PAR + UV-A + UV-B radiation treatments for 12 h under a 4 temperature conditions (5, 10, 15 and 20 °C), followed by a 12-h recovery period in dim light without UV. A thermoregulated waterbath (Digit-Cool, Selecta, Spain) was used to set the different temperatures, whilst illumination was provided by three types of fluorescent lamps: UV-B-313 emitting UV-B; UV-A-340 emitting UV-A (Q-Panel, USA) and and TL-D 36 W/54-765 emitting PAR (Philips, Thailand). Three UV treatments were obtained by covering the cell culture with different cut-off filters: Ultraphan 295 (Digefra, Germany) for PAR + UV-A + UV-B condition, Ultraphan 320 for PAR + UV-A, and Ultraphan 400, for PAR treatment. The experimental UV irradiances were set at 0.25 W m-2 for UV-B and 0.95 W m-2 for UV-A, whilst the PAR irradiance was of 10 μmol m-2 s-1. Total radiation dose during the 12 h exposure was 10.8 kJ m-2 for UV-B and 40.5 kJ m-2 for UV-A. The radiation levels were measured using the RAMSES-ACC2-UV–Vis hyperspectral radiometer.
Chlorophyll fluorescence measurements
The photosynthetic performance of Chlorella was measured before and after exposure to different temperatures and radiation treatments using an amplitude modulation fluorometer (Water PAM, Walz, Effeltrich, Germany). After a 12-h exposure, as well as after a 12-h recovery period, the samples were kept for 10 min in darkness and the maximum quantum yield (Fv/Fm) was subsequently measured.
The effect of UV radiation and temperature was assessed by comparing the inhibition of Fv/Fm, that was calculated as the percentage of decrease between the values measured in PAR + UV-A and PAR + UV-A + UV-B and values measured in samples exposed only to PAR. Likewise, the recovery was estimated by comparing the Fv/Fm values of the samples treated with UV radiation with those treated only with PAR.
The variation in the incident solar radiation of UV-B, UV-A and PAR at different depths (0, 10, 20, 30, 40 cm) was compared using nonparametric analysis of variance (Kruskal-Wallis). The variation in the responses of the photosynthetic parameters to the UV radiation exposure and recovery at different temperatures, were compared through a two-way variance analysis (ANOVA). Post-hoc comparisons were carried out using Tukey HSD test. In both analyses, the ANOVA assumptions (variance homogeneity, normal distribution) were examined through the Levene’s and Kolmogorov-Smirnov tests, respectively.
In situ solar irradiance and temperature
Maximum Photosynthetically Active Radiation (PAR) levels, measured in snow column, during the study period
PAR (μmol photon m-2 s-1)
Levels of solar UV radiation (W m -2 ) in the snow column at different depths measured using a RAMSES hyperspectral radiometer. Values correspond to 8-19 measurements per depth. The spectral characteristics are shown in Fig. 2c
Mean ± S.D.
15.8 ± 0.97
0.35 ± 0.01
163.7 ± 14.72
1.31 ± 0.33
0.018 ± 0.00
19.0 ± 4.12
0.69 ± 0.07
0.007 ± 0.00
11.5 ± 1.55
0.30 ± 0.01
0.002 ± 0.00
6.5 ± 0.34
0.42 ± 0.06
0.003 ± 0.00
7.6 ± 1.72
Results on photosynthetic parameters measured using amplitude modulation fluorometer (Water PAM)
Effects of the experimental treatments on maximum quantum yield (Fv/Fm) analysed by two-way ANOVA
Temperature x Radiation
Temperature x Radiation
Photosynthetic characteristics and the light environment
Our results show that at the sampling location in Fildes Peninsula, 10 cm below the snow surface irradiance does not exceed 350 μmol m–2 s–1, which matches well the average light required for saturation of photosynthesis determined in this study for Chlorella sp. (276 μmol m–2 s–1). Using the number of hours per day at which algae are exposed to saturating irradiances (the so-called Hsat), one can argue that photosynthesis of these microalga is not limited by at least for 10 h at a depth of 10 cm and 12–13 h at the surface of the snowpack, during sunny conditions. In general, these light requirements are in the lower ranges described for Chlamydomonas from Giant Mountains, Czech Republic and clearly lower than light requirements of 523–826 μmol photons m–2 s–1 measured in an Arctic population of Chlamydomonas nivalis . In contrast to Chlorella sp., the high Ek values determined in Chlamydomonas are indicative of that these algae are exposed to photoinhibitory levels of PAR, which could have negative effects on photosynthesis. In fact, it is well documented in this genus that excess of irradiation results in the formation of robust, red pigmented cysts [33–35], which are also mostly located at the surface of the snowpack . Although we did not perform in situ measurements of photosynthesis, the high levels of solar radiation recorded during midday in a sunny day at Fildes Peninsula (exceeding 1200 μmol photons m–2 s–1) suggest that Chlorella can suffer considerable photoinhibition of photosynthesis, at least when exposed to high irradiances close to the snow surface. This is exacerbated by snow reflecting most of the long wavelength radiation , directly affecting the light extinction patterns, mostly due to the changes in phase transitions of water . It must be emphasized that in our laboratory study, levels of PAR used in the incubations were considerably lower than current irradiances measured in the field (PAR was maintained low to avoid photoinhibition and mask UV effects) and thus we cannot evaluate the impact of high PAR on the physiology of this alga.
Effects of temperature on UV stress tolerance
Due to its ubiquitous character, many species of Chlorella have been described as eurythermal microorganisms, which can inhabit all type of freshwater and soil environments . This capacity to cope with different thermal conditions has also been recognized for isolated strains of Chlorella sp. from Antarctic . In our study, Chlorella sp. was visually more abundant below 10 cm where temperatures along the day ranged between 0 and 3.8 °C. Apparently, in this environment, algae find a more stable microhabitat with lesser temperature variations . This allows us to argue that excess UV radiation at strata close to the surface would be the key factor limiting the proliferation of Chlorella sp. at depths < 10 cm. In fact, our results indicate that Chlorella sp. is sensitive to UV radiation but not to temperature. Regarding the levels of UV radiation recorded at depths below 10 cm (0.01 W m-2 for UV-B and 1.3 W m-2 for UV-A), it could be argued that microalgae were not exposed to detrimental UV conditions. For example, in situ measurements carried out in the snowfields of the Rocky Mountains, Wyoming, with abundant populations of Chlamydomonas nivalis indicated that maximal transmittance of UV-B radiation was close to 4 cm .
The inhibition of the maximum quantum yield (Fv/Fm) of Chlorella sp. was wavelength dependent. Under PAR + UV-A + UV-B treatment, fluorescence values decreased by 15 % after exposures of 5 to 20 °C. For the PAR + UV-A treatment, inhibition of Fv/Fm did not exceed 7 %. However, the recovery of the samples exposed to PAR + UV-A was in the range of 90–100 % relative to PAR control, while recovery in algae exposed to PAR + UV-A + UV-B varied between 80 and 95 %. These results highlight the tolerance of Chlorella to the UV exposure, at least for periods close to 12 h and high UV-B:UV-A ratio. Studies carried out with UMACC 237, another Antarctic Chlorella strain, revealed a higher tolerance to UV-B compared to strains of the same genus isolated from temperate and tropical regions . Apparently, exposure to enhanced UV radiation in snow living populations of Chlorella stimulates the activity of antioxidant enzymes, such as catalases and superoxide dismutase [23, 41] or enhance the synthesis of protective compounds like secondary carotenoids (e.g. in Chlorella zofingiensis) or mycosporine-like amino acids (MAAs) . However, when algae were exposed to higher temperatures, repair processes in Antarctic strains increase significantly . This could be a confirmation that elevated temperatures can ameliorate the detrimental impact of UV radiation as has been reported in Antarctic macroalgae .
Implications for snow algal ecology in scenarios of climate change
Recent reviews dealing with the ecology of snow algae and in general of extreme cold-adapted organisms [2, 21] emphasize the urgent need for physiological and molecular studies that allow identifying the adaptive and acclimative strategies that snow algae exhibit in response to environmental factors beyond their tolerance threshold. Based on a scenario of extended melt periods in maritime Antarctica with concomitant higher impact of elevated temperature and UV radiation, the examination of stress tolerance mechanisms is essential to understand and predict near-future impacts of climate change especially in polar regions where snowfields and their algal communities have an important role on the biogeochemical fluxes . Snow algae are probably the most sensitive biological indicators of present and future scenarios of regional warming and meltdown in vast sectors of Antarctica, especially at ecologically relevant (seasonal and interannual) scales. In addition to their important role as primary producers, polar extremophiles are involved in exchange of reactive gases with the atmosphere (e.g. N2, CO2, dimethyl sulfoxide, etc.) [2, 45] and in snowfields in the maritime Antarctica, they play important subsidiary roles through the melting runoff, food web and degradation products [7, 8]. The impact that these processes will have on in the biogeochemical cycles of the whole coastal system in this region is unknown and prompt for further research.
Overall, our findings revealed that Chlorella sp. isolated from a snow microalgal community in maritime Antarctic not only shows high photosynthetic efficiency at ambient conditions, but also exhibits tolerance to solar radiation under higher temperatures. Avoiding the highly UV exposed snow surface and possessing a capacity for recovery after inhibition of photosynthesis by UV radiation appear as two important strategies of Chlorella sp. in these ecosystem . However, it remains open how these algae will endure the future Antarctic summer, characterized by warmer temperatures and less snow, in which they will exposed to high solar radiation.
The study was supported by the PhD Grant DT_09-14 from Instituto Antártico Chileno (INACh) and Project ANILLO ART1101, from Conicyt. The logistic support provided by INACh and the collaboration of the staff of Base Julio Escudero Station are greatly acknowledged. This is contribution # 9 of the ANILLO ART1101 project.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The 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.
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- Amoroso A, Domine F, Esposito G, Morin S, Savarino J, Nardino M, Montagnoli M, Bonneville JM, Clement JC, Ianniello A, Beine HJ (2010) Microorganisms in dry polar snow are involved in the exchanges of reactive nitrogen species with the atmosphere. Environ Sci Technol 44:714e719View ArticleGoogle Scholar | <urn:uuid:fa651517-b58f-47eb-81d4-6e713287f9e0> | 2.59375 | 6,890 | Truncated | Science & Tech. | 39.643035 | 95,616,267 |
The arc3 (accumulation and replication of chloroplast) mutant of Arabidopsis thaliana has a small number of abnormally large chloroplasts in the cell, suggesting that chloroplast division is arrested in the mutant and ARC3 has an important role in the initiation of chloroplast division. To elucidate the role of ARC3, first we identified the ARC3 gene, and determined the location of ARC3 protein during chloroplast division because the localization and spatial orientation of such division factors are vital for correct chloroplast division. Sequencing analysis showed that ARC3 was a fusion of the prokaryotic FtsZ and part of the eukaryotic phosphatidylinositol-4-phosphate 5-kinase (PIP5K) genes. The PIP5K-homologous region of ARC3 had no catalytic domain but a membrane-occupation-and-recognition-nexus (MORN) repeat motif. Immunofluorescence microscopy, Western blotting analysis and in vitro chloroplast import and protease protection assays revealed that ARC3 protein was soluble, and located on the outer surface of the chloroplast in a ring-like structure at the early stage of chloroplast division. Prokaryotes have one FtsZ as a gene for division but have no ARC3 counterparts, the chimera of FtsZ and PIP5K, suggesting that the ARC3 gene might have been generated from FtsZ as another division factor during the evolution of chloroplast by endosymbiosis.
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van Lipzig, Nicole P.M.
- Journal Article
Rights / licenseCreative Commons Attribution 3.0 Unported
Precipitation amounts over East Africa have been declining over the last decades. These changes and future climate change over the region are highly debated. This study analyzes drivers of future precipitation changes over East Africa by applying a classification of circulation patterns on 15 historical and future members of the COordinated Regional climate Downscaling EXperiment. Typical circulation types (CTs) are obtained. Under a high emission scenario, changes in the frequency of occurrence of these CTs attribute for 23% of the total change in precipitation over East Africa by the end of the century. The remaining part (77%) is not related to East African synoptics, e.g. changes in moisture content, local/mesoscale feedbacks, and changes in moisture influx. These other effects comprise increases in precipitation close to the equator and the Somali region, while decreases are found over northwestern Ethiopia, the Sudan region and the lake areas Show more
Journal / seriesEnvironmental Research Letters
Pages / Article No.
PublisherInstitute of Physics
SubjectCirculation classification; Regional climate modeling; Precipitation; Weather atlas; Thermodynamics; Large-scale synoptics
Organisational unit03778 - Seneviratne, Sonia
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A mole is defined as quantity of a given substance that contains as many molecules or formula units as the number of atoms in exactly 12g of carbon-12.
The number of atoms in 12-g sample of carbon-12 is called Avogadro's number which is 6.02 x 1023.
Terms mole like a dozen refers to a perticular number of things.A dozen egg equals 12 eggs and a mole of ethanol equals 6.02 x 1023 molecules.
1 mole of H atoms = 6.02 x 1023 H atoms
1 mole O atoms = 6.02 x 1023 O atoms
1 mole H2 molecules = 6.02 x 1023 H2 molecules
1 mole H2O molecule = 6.02 x 1023 H2O molecules
In using terms moles for ionic substances we mean the number of formula units of substance.For example,
A mole of sodium carbonate,Na2CO3 is a quantity containing 6.02 x 1023 Na2CO3 units.But each formula units of Na2CO3 contains two Na+ ion and one CO32- ion.So, a mole of Na2CO3 also contains
2 x 6.02 x 1023 Na+ ion and 1 x 6.02 x 1023 CO32- ion
Mole and Molar mass
A mole represents not only a specific number of particles but also a definite mass of a substance as represented by its formula. | <urn:uuid:708af6e5-ddc5-48fa-bd05-1a1e55a20f5f> | 3.59375 | 302 | Tutorial | Science & Tech. | 82.56607 | 95,616,304 |
Genetics as it applies to evolution, molecular biology, and medical aspects.
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hey der ppl can ne1 ...pls pls help me by tellin me excatly wat is ligation mediated PCR.... pls help me as soon as possible as i hav my xamz on my head ....
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Basically, if you know only part of your sequence and have only one primer, you will need to ligate a linker or adaptor (for the second primer) in order to isolate unknown sequence. It is greatly used in isolation of the insertion flanking sequences in mutants.
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Authors: Enos Øye
We show that a simplified force between the electron and the nucleus solves Quantum Mechanics in the simplest way possible. We update and rewrite Bohr's postulates, we show the simple relation between the electric and magnetic force, we show how light is emitted, and find a new term for the fine structure constant which is the simplest term there is. Simplified Orbital Mechanics results in a new atomic model which allow mathematically the observed electron cloud. All calculations can be found in this google spreadsheet: https://docs.google.com/spreadsheets/d/1jE6hjJNPcY7h98DkkGVEJiO9x3LK-_ZK6553cd2b_M8/edit#gid=498321884
Comments: 10 Pages.
[v1] 2018-04-03 09:07:54
Unique-IP document downloads: 45 times
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Video How Devils Heal Forests
Video How Devils Heal Forests
Learn about the science behind this story: https://rewildingaustralia.org.au/devilfacts
One of the most exciting scientific findings of the past half century has been the discovery of widespread trophic cascades. A trophic cascade is an ecological process which starts at the top of the food chain and tumbles all the way down to the bottom.
Many of us would likely be astonished to learn that Tasmanian devils were never unique to Australia’s island state of Tasmania as they are today - but rather evolved over millions of years on mainland Australia, where they played a vital role as a keystone species that helped maintain the health of entire forest ecosystems.
Prior to European arrival, Australia’s ecosystem evolved in near isolation from the rest of the world for over 40 million years, forming deep, complex interrelationships that helped maintain ecosystem resiliance. However, foxes and cats introduced in the first hundred years of British arrival, quickly ate their way across the continent, growing in numbers, fuelled by a vast European rabbit population which had been destroying the vegetation undergrowth that was essential to providing shelter to small mammals like bandicoots, bettongs, and potoroos.
It turns out that these small mammals are essential to maintaining the health and resilience of entire forest ecosystems. As these animals forage for food, they dig the ground, mixing organic matter into the soil, spreading fungi and seed. The burying of leaf litter reduces fuel loads, creating conditions for cooler, less destructive bushfires.
Larger mammals, like the wallabies and kangaroos, while often spared from the jaws of cats and foxes, became overabundant and in the absence of native predators, further added to the loss of vegetation cover.
In studying Tasmanian ecosystems, we have learned that the very presence of Tasmanian devils change the behaviour of the other animals in the ecosystem. Cats tend to avoid areas with healthy populations of devils, which allow small native mammals to survive in the landscape and perform their role as ecosystem engineers. By reintroducing devils, animals like wallabies and possums, might recognise the Tasmanian devil as a species to avoid, helping to reduce grazing pressure on ground cover by pushing possums back into the trees and some of the wallaby species deeper into the forests.
As ground vegetation is restored and cats find it more difficult to function, opportunities for small mammals to find a place to live and hide from predators will increase. While not yet tested, modelling suggests the effect of devils on foxes may be similar to those on cats.
The bandicoots, bettongs, and potoroos will return to the forest floor, helping the forests to regenerate and helping mitigate the impact of devastating bushfires. With cooler bushfires, pockets of habitat might remain unburnt, providing further safe havens for wildlife and increasing ecosystem resilience to future threats. By returning the Tasmanian devil, we may be able to help heal the forests.
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Edited By: Kai Schmidt-Soltau and Michael M Cernea
Programs for creating national parks for biodiversity conservation often run into a vexing dilemma when the intended park areas are inhabited by indigenous populations. These populations are described as damaging the biodiversity, and the simplistic "solution" implemented by many developing countries' governments is their involuntary displacement. The forthcoming study, written by two internationally known social scientists, demystifies both this rhetoric and "rationale" behind this common practice. The study's authors apply a new theoretical model of poverty risks to the analysis of empirical findings from 9 parks in 6 countries of the Congo basin. They show how forced displacements do not preserve people's livelihood but destroy it. The authors argue for policy changes, in favour of balanced approaches.
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The situation in the Gulf was looking good for a while. But the recent discovery
of a massive, invisible underwater oil plume is changing that outlook. Here are some of the latest developments that bode ill for those hoping for a quick cleanup:
- The New Plume "Take Manhattan, turn it into oil and drop it in the Gulf," writes Discover's Andrew Moseman. "That’s the size of the submerged oil plume that scientists found ... casting more doubt on those claims that the plumes weren't so bad, or that most of the oil has been accounted for." Moseman notes "the team's numbers draw them into direct conflict with those provided by the government," but points out, too, that "everybody's estimates are complicated by the sheer difficulty of tracking and predicting the flow of oil in water."
- How Much Oil? 'Pick a Number' The latest estimate, writes Randy Rieland at environmental hub Grist, is that "only 10 percent of the oil that gushed out of the Deepwater Horizon well was 'actually removed from the ocean.'" That's one of the more "pessimistic" estimates thus far, and comes from an oceanographer at Florida State University. It's also "wildly at odds with what the feds have been saying--that as much as 75 of the oil is gone."
- Dead Zones Julia Whitty at Mother Jones focuses on a separate study, a "simulation of oil and methane leaked into the Gulft" which "suggests that deep hypoxic zones, also known as dead zones, could form near the source of the pollution. ... Dead zones," she explains, "occur where oxygen levels have dropped blow the threshold to support most marine life." Here's the problem, she continues: "the last thing the Gulf of Mexico needs is anymore dead zones. It's already home to the second largest dead zone on Earth, a side-effect of fertilizer overuse in North America's breadbasket."
- And the Blame Game "The real story," insists Gawker's Jeff Neumann, "is the growing spat between BP and Transocean Ltd. over who did what wrong, and when they did it and what they've done with the evidence." He looks at Transocean's accusation that BP withheld information when the rig exploded.
This article is from the archive of our partner The Wire.
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Explosive Materials. The greater the explosivity, the greater the amount of fragmentation Lava & rock material sent into the air is called Tephra : ( Greek, for ash) is a generic term for any airborne pyroclastic accumulation
Pyroclastic flows: (fire fragments) Individual eruptive fragments are called
LAPILLI-- Pea- to walnut-size (2 to 64 mm). They often look like cinders
ASH -- Very fine-grained fragments (< 2 mm), generally dominated by broken glass shards
unusual spaces in the ash layer that, when filled with plaster,
were casts of people that had been caught by the volcanic debris flow and could not escape. | <urn:uuid:e7fa34c9-4a8b-4d6d-852d-bfab6aedafe8> | 3.375 | 146 | Knowledge Article | Science & Tech. | 26.923231 | 95,616,348 |
Protecting MySQL from SQL Injection Attacks with PHP
A guide on how to properly protect your MySQL database from SQL injection attacks by using a little common sense, good programming practices and PHP.
What is a SQL injection?
A SQL injection attack occurs when a malicious user attempts to add their own SQL statements into your SQL statements. This could be used to return account information, add Spam links to content or to mess up the database causing the site to crash.
A common activity on websites is to query a database for page information and pull off the content dynamically from the database. In this instance a query string parameter would be passed into SQL select statement to retrieve details for the requested page.
For example, you could have a URL like this (it could be developed like this or rewritten using mod_rewrite):
Within the php code you can retrieve these values and query the database like this:
$reqPage = $_REQUEST['page']; $reqSection = $_REQUEST['section']; $query = "SELECT * FROM pages WHERE pageName = '$reqPage' AND pageSection = '$reqSection'";
Now this will work fine as long as valid parameters are passed into the query, and for the majority of the time this will be true, but what will happen if a malicious user decides to hack your website and cause problems? This can easily be done by injecting SQL into the parameters and could be used to delete all the records in the table for example.
If a malicious user was to type into the browser:
http://www.domain.com/index.php?page=tutorials§ion='; DROP TABLE users;
This would cause the $reqSection to contain the SQL injection and when combined into the query the final SQL as executed by the server will become:
SELECT * FROM pages WHERE pageName = 'tutorials' AND pageSection = '''; DROP TABLE users;
This is obviously a very dangerous situation to be in and should be avoided at all costs.
What are the solutions?
A golden rule when programming is to validate/escape/prepare ALL user inputs, query string parameters, form fields and so on.
PHP Magic Quotes
Magic quotes were introduced into early versions of PHP to combat these threats. Magic Quotes does this by escaping single and double quotes however this method should not be used for a number of reasons.
Firstly, there is no guarantee that a server will have this enabled, by default PHP 5.2 onwards disables the option and PHP 6 has no support for it.
Second, you cannot depend on magic quotes to protect against all attacks.
Third it cannot protect against extended characters.
Finally it causes all quotes entered into the database to be escaped, polluting the data meaning that you will have to filter them out when you query the data again.
It is always safer to escape strings yourself and there is a quick and dirty method which uses the PHP htmlspecialchars function. This function will convert all non-alphanumeric characters into their html equivalents, so a single quote becomes ' and a double quote becomes " but only if it is set up properly (see htmlspecialchars for reference on this).
This method has been distributed as a way of escaping strings for SQL, however this is not the purpose of the function. There are still characters that will not be escaped, such as the forward slash, and as such it should not be used.
Some methods of protection focus on escaping or removing bad characters, but one of the most effective methods is to remove everything but known good data.
If you are asking for an age or date then the string should only contain numerical values plus a forward slash. If there are any other characters - such as a quote, remove them.
This cannot always work, because malicious injection attacks do not always use special characters, especially if numbers are being compared, since numeric values are not enclosed in a single quote in the statement.
$parameter= "1 OR 1=1"; $query = "SELECT * FROM accounts WHERE id = $parameter";
This can result in the following sql being executed, a statement which will always return all rows.
SELECT * FROM accounts WHERE id = 1 OR 1=1
However if the parameter is checked for numeric characters only, anything else dropped from the string or returned to the user as a validation error, then you can be reasonably sure that the value is safe. However the same cannot be true for alphanumeric strings.
Proper SQL String Preparation
The best solution (IMO the only solution) is to use a function to prepare your SQL query. From PHP version 5 onwards there is support for MySql prepared statements using the mysqli library. This preparation is a function of the class, which will automatically escape and protect your SQL queries.
$db_connection = new mysqli("localhost", "user", "pass", "db"); $statement = $db_connection->prepare("SELECT pageTitle FROM pages WHERE pagename = ?"); $statement->bind_param("s", $reqPage); $statement->execute();
WordPress versions greater than 2.6 have an integrated prepare function to protect against injection attacks and features a string format style parameter.
$query = $wpdb->prepare("SELECT pageTitle FROM pages WHERE pagename = %s", $reqPage); $result = $wpdb->get_var($query);
Most other database providers provide a prepare function; please refer to the documentation for your product for exact usage.
Last updated on: Thursday 22nd June 2017
How misusing untrusted data can lead to your application being hacked
How simple server response headers can form a picture of how your application works
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By: Jane Drake and Ann Love
56 pages, illus
From killer toads, feral felines, and brown tree snakes to multiple invaders in Lake Victoria and the Great Lakes, Alien Invaders focuses on wave after wave of invaders that affect our ecosystems and the side-effects of climate change and modern global travel on our world today. Environmentalists and coauthors Jane Drake and Ann Love present the concepts of endangered species and biodiversity in this informative look at alien invaders and how they impact our world.
From the days of sailing ships and shipboard rats to the fungus that sparked the Irish potato famine to the beautiful but deadly purple looseleaf strangling native wetlands, they examine extinctions and endangerments directly attributable to these alien invaders. Learn where the invaders originated, how they traveled, where they settled, what they displaced, why the invaded natural system was vulnerable, and what can be done. Kids can determine if they themselves are invaders or savers and how they can help.
This exploration of a timely topic, coupled with the lively detailed illustrations of Toronto artist Mark Thurman, inspire kids and adults alike to be more observant and protective of our natural world.
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A more watery lower mantle would churn faster.
Five times as much water as in all the world’s oceans may lurk deep below its surface.
Geologists have divined water where you might least expect it: 1,000 kilometres below the Earth’s surface. Here, rocks heated to over 1,000 oC and squeezed under high pressures may harbour around five times as much water as in all the world’s oceans. This could give clues to how the Earth formed and how it behaves today.
Between 650 and 2,900 km below the Earth’s surface hot, compressed minerals surround the planet’s iron-rich core. Called the lower mantle, this material may hold up to 0.2 per cent of its own weight in water, estimate Motohiko Murakami, of the Tokyo Institute of Technology in Japan, and colleagues1.
Water would lower the melting point of rocks in the lower mantle and increase their viscosity. Over millions of years, the mantle churns like a pan of hot soup. This moves the tectonic plates and mixes the mantle’s chemical components. A more viscous mantle would churn faster.
The take-up of water by minerals in the lower mantle might also affect the ease with which tectonic plates sink deep into the Earth. As the plates descend, heat up and become squeezed, the water that they release might soften the surrounding mantle and ease their passage.
There is already thought to be several oceans’ worth of water slightly higher in the mantle, at a depth of around 400-650 km. This region is called the transition zone, as it is between the upper and the lower mantle.
The lower mantle’s minerals can retain about a tenth as much water as the rocks above, Murakami’s team finds. But because the volume of the lower mantle is much greater than that of the transition zone, it could hold a comparable amount of water.
"The findings will boost the debate about how much water is locked away in the mantle," says geologist Bernard Wood of the University of Bristol, UK. Until now, he says, "most people would have argued that there isn’t much water in the mantle". A similar study two years ago concluded that there isn’t much water down there at all2.
Taking on the mantle
Murakami’s team mimicked the lower mantle in the laboratory. They studied the three kinds of mineral thought to make up most of the region: two perovskites, one rich in magnesium, the other in calcium, and magnesiowustite, a mixture of magnesium and iron oxides.
To recreate the its furious conditions, the researchers used a multi-anvil cell. This heats materials while squeezing them between hard teeth. Having baked the minerals at around 1,600 oC and 250,000 atmospheres, the team measured how much hydrogen the rocks contained using secondary-ion mass spectrometry. This technique blasts the material with a beam of ions and detects the ions sprayed out from the surface.
Any hydrogen in the rocks presumably comes from trapped water, an idea that other measurements support. The researchers found more hydrogen than previous experiments had led them to expect.
PHILIP BALL | © Nature News Service
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
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Materials Sciences
19.07.2018 | Earth Sciences
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For the first time, an international research program involving the Department of the Interiors U.S. Geological Survey has proven that it is technically feasible to produce gas from gas hydrates. Gas hydrates are a naturally occurring "ice-like" combination of natural gas and water that have the potential to be a significant new source of energy from the worlds oceans and polar regions.
Today at a symposium in Japan, the successful results of the first modern, fully integrated production testing of gas hydrates are being discussed by an international gathering of research scientists. The international consortium, including the USGS, the Department of Energy, Canada, Japan, India, Germany, and the energy industry conducted test drilling at a site known as Mallik, in the Mackenzie Delta of the Canadian Arctic. This location was chosen because it has one of the highest concentrations of known gas hydrates in the world.
The United States is committed to participating in international research programs such as this one to advance the understanding of natural gas hydrates and the development of these resources. Even though gas hydrates are known to occur in numerous marine and Arctic settings, little was known before the Mallik project about the technology necessary to produce gas hydrates.
A. B. Wade | EurekAlert!
New creepy, crawly search and rescue robot developed at Ben-Gurion U
19.07.2018 | American Associates, Ben-Gurion University of the Negev
The role of Sodium for the Enhancement of Solar Cells
17.07.2018 | Max-Planck-Institut für Eisenforschung GmbH
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Materials Sciences
19.07.2018 | Earth Sciences
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Hurricanes strike the US with regularity, however there’s nothing on list it truly is in any respect like Storm Harvey’s pummeling of Houston. Understanding the chance of that variety of wind and rainfall happening lower back is imperative if we intend to rebuild infrastructure that’s going to live on to its expected expiration date. However freakish storms like Harvey make chance calculations frustrating. These storms have no historical precedent, so we now have no idea how traditionally they show up; and the underlying probability of these hobbies is moving as our planet grows warmer.
An MIT professor named Kerry Emanuel, even if, has helped strengthen a system that analyzes storm frequency in a warming world. Using it, he has found that Harvey-sized rainfall might go from being incredibly rare to having an 18-percent risk of going on in any given year by means of the quit of this century.
Rainfall experiences lots of nearby variations, and web sites within a few miles of every different can often see very distinctive numbers. To get a clearer image of a storm’s ruin, the learn group has settled on a figure known as the “area integrated rainfall.” With the aid of that measure, Harvey is the biggest storm on checklist, having dumped 850 millimeters on the Houston region. It’s intense, but there are different storms of equivalent magnitude. Texas saw greater than 500mm of rain from the remnants of typhoon Patricia just two years until now.
Storms of this measurement are a rarity within the historic checklist, however that list will get spotty while you go again greater than a century. Climate models might supply a improved sense of their probably frequency, but they have got bad spatial resolution—you may’t effectively adaptation a storm without an extreme quantity of computing strength. Emanuel worked with other researchers to handle this drawback, creating a main issue during which a excessive-resolution edition of a typhoon floats like a bubble within the larger context of a worldwide local weather model. Emanuel has now used this technique to analyze Harvey.
First of all, he ran a suite of seven climate models by means of the conditions that prevailed between 1980 and 2016. Tropical disturbances have been seeded in these runs, and the method selected people who developed into hurricanes and struck Texas within 300 kilometers of Houston. In accordance with this prognosis, storms with anyplace above 450 millimeters of rainfall are incredibly rare; those with more than 800mm are very nearly unprecedented. “Harvey’s rainfall in Houston become ‘biblical,'” Emanuel concludes, “within the sense that it likely passed off round as soon as on the grounds that the Historical Testament became written.”
In case we expand the diagnosis out to the Texas coast as a whole, the possibilities naturally go up just a little. The versions recommend that a storm able of dumping that tons rain would strike Texas about once a century under the local weather prerequisites that prevailed from 1980 to 2000. Harvey-scale storms remain so infrequent as to make it unimaginable to perform a statistical analysis on them.
Infrequent, but getting much less so
It really is seemingly magnificent news. A century is longer than we expect most infrastructure to final, and a lot of areas in Texas should not have a great deal in the way in which of infrastructure first of all. But the widely used year we’re now experiencing is already warmer than most of the ones from 1980 to 2000, which argues towards complacency.
To get a superior sense of how local weather exchange is skewing these odds, Emanuel became to the IPCC’s commercial enterprise-as-normal emissions situation (termed RCP 8.5) and ran the local weather models as a result of it as input, focusing on the final twenty years of the present century (in other phrases, taking a look 60 to 80 years ahead). The news isn’t exceptional: “Rainfall in excess of 500 mm, which is round a as soon as-in-2,000-yr event within the late 20th century, will become a as soon as in a a hundred-yr event by using the cease of this century.”
And it truly is only for Houston. For Texas as a whole, this sort of rain goes from being once a century to occurring each 5.5 years.
Emanuel did not promptly edition the latest conditions. But when we anticipate there is a straight line between the end of the closing century and the end of the 21st, then the chances of this kind of storms is now as soon as each 16 years. Remember, it had been as soon as a century just 17 years in the past.
Almost always, the sort of prognosis takes time, both to operate and to make its way using peer review. To get his consequences out so quickly after Harvey, Emanuel made up our minds to use his fame as a member of the Country wide Academies of Science, which let him decide upon his personal peer reviewers, who have been likely to be pleasant and get the evaluate executed promptly. So his findings regularly have not faced as rigorous a assessment as they could have. Nevertheless, the system used for his diagnosis has been concern to peer evaluate plenty of instances, and Emanuel is striking his recognition as a scientist on the road here.
And the consequences make experience. With a warming atmosphere, evaporation will increase, and the air is competent of maintaining extra moisture. It’s predicted to accentuate hurricanes as this century goes on. As for Houston, the implications advocate that rebuilding efforts won’t anticipate that something like Harvey will never take place back. And the rest of Texas have to view Harvey as a warning.
PNAS, 2017. DOI: 10.1073/pnas.1716222114 (About DOIs).--- | <urn:uuid:5244f742-fde6-4f9b-8ec4-95613f5748e9> | 3.09375 | 1,190 | Truncated | Science & Tech. | 46.666879 | 95,616,483 |
A new study reveals that the Kurly protein is required for the proper orientation and movement of tiny hair-like projections called cilia. Defects in cilia are linked to human disease.
A new study of a protein found in cilia - the hair-like projections on the cell surface - may help explain how genetic defects in cilia play a role in developmental abnormalities, kidney disease and a number of other disorders.
The researchers at Princeton University and Northwestern University found that the protein, which goes by the name C21orf59 or "Kurly," is needed for cilia to undulate to keep fluid moving over the surface of cells. They also found that the protein is needed during development to properly orient the cilia so that they are facing the right direction to move the fluid.
"It's extremely exciting that we've found a single protein that is responsible for these two functions - orientation and motility - in cilia," said Rebecca Burdine, an associate professor of molecular biology at Princeton University. "Despite their importance in human disease, very little is known about how cilia motility and orientation are coordinated, so this protein will provide an important gateway into looking at this process." The finding is published online and in the March 1 issue of the journal Cell Reports.
The studies were conducted in zebrafish at Princeton and in African clawed frogs at Northwestern. In the zebrafish kidney, the researchers found that the Kurly protein enabled cilia to orient themselves in a uniform direction, and most importantly, in the proper direction to facilitate the flow of fluid along the narrow channels in the kidney. In frogs, the cilia on skin cells help move fluid along the surface of the animal during its larval stage. In both cases, knocking out the gene for Kurly caused the cilia to orient incorrectly thereby losing their ability to move in the waving fashion that helps push fluid along.
The discovery of Kurly's role in cilia movement and orientation stemmed from work in the Burdine lab on fetal organ development, specifically an investigation of mutations that alter the left-right asymmetric orientation of the heart. Such mutations can result in an organ that is working properly but is an exact mirror image of a normal heart. During a search for genes involved in this left-right patterning, the Burdine team discovered that mutations in a gene they called kur, which codes for the Kurly protein, were linked to errors in left-right orientation in zebrafish heart.
As the team investigated kur, they noted that the mutation also affected the function of cilia. It has been known for some time that cilia are important for a number of jobs, from sensing the environment to facilitating fluid flow, to ensuring that the lungs excrete inhaled contaminants. Cilia genetic defects are linked to a number of human diseases, including polycystic kidney disease, respiratory distress, hearing loss, infertility, and left-right patterning disorders such as the one Burdine studies.
Researchers in Burdine's laboratory found that Kurly's role in cilia movement stems from its ability to ensure proteins called dynein arms are correctly located in the cilia. When the researchers knocked out the kur gene, the dynein proteins failed to form in the proper location.
The finding that a single protein is involved in both movement and orientation is surprising, said co-first author Daniel Grimes, a postdoctoral research associate in the Burdine lab. "These are two aspects that are both required to generate fluid flow, and we'd like to know how they are linked molecularly. This work adds a new gene that aids this discovery."
The gene for Kurly has also been detected in relation to human cilia disorders, so the work may have an impact on understanding the mechanisms of human disease, Grimes added. The researchers also found that the mutation they discovered rendered the Kurly protein sensitive to temperature, and used this trait to find that the Kurly protein may be involved in initiating movement rather than keeping the cilia moving once they've started.
The team also explored proteins that interact with Kurly. The Northwestern team showed that when the kur gene was inactivated using a gene-editing technique called CRISPR-Cas9, the lack of a functioning Kurly protein led to the mis-positioning of a second protein on the cell surface called Prickle2, which helps cells know which direction they face. Without proper Prickle2 positioning, the cilia pushed fluid in the wrong direction.
The study of the Kurly protein involved Grimes as well as two additional co-authors, Kimberly Jaffe and Jodi Schottenfeld-Roames, a former postdoctoral researcher and graduate student respectively, in the Burdine lab. The initial studies on the Kurly protein were conducted as part of an undergraduate research project by Tse-shuen (Jade) Ku, Class of 2007. Additional work was contributed by Nicholas Morante and José Pelliccia, graduate students in the Burdine lab.
The work at Northwestern University was performed in the laboratory of Brian Mitchell with the assistance of Michael Werner and Sun Kim.
Catherine Zandonella | EurekAlert!
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Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
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The genome of complex organisms is stashed away inside each cell's nucleus, a little like a sovereign shielded from the threatening world outside. The genome cannot govern from its protective chamber, however, without knowing what's going on in the realm beyond and having the ability to project power there.
Guarding access to the nuclear chamber is the job of large, intimidating gatekeepers known as nuclear pore complexes (NPCs), which stud the nuclear membrane, filtering all of the biochemical information passing in or out. In new research, scientists have for the first time glimpsed in three dimensions an entire subcomplex of the NPC; it's the key building block of this little understood and evolutionarily ancient structure, an innovation fundamental to the development of nearly all multicellular life on earth.
The findings, by Martin Kampmann, a graduate student in John D. Rockefeller Jr. Professor G¨¹nter Blobel's Laboratory of Cell Biology, add details to an unfolding picture of cellular evolution that shows a common architecture for the NPC and the vehicles that transport material between different parts of the cell, called coated vesicles. As early as 1980, Blobel proposed that internal membranes of cells ¨C such as those encompassing the nucleus and vesicles ¨C evolved from folds or invaginations of the outer cell membrane. Rockefeller scientists Brian Chait and Michael Rout suggested in a 2004 paper in PLoS Biology that both the NPC and vesicle coats, which contain similar protein folds, evolved from ancient membrane-coating proteins that stabilized these primordial internal membranes.
"So far, it's been unclear how these ancient folds work in the nuclear pore complex", Kampmann says. "Now we can see that the ¦Á-solenoid folds form long, flexible arms and hinges that end in the more compact, globular ¦Â-propellers. The same architectural principle is found in clathrin, a common component of vesicle coats."
In research to be published online Sunday in Nature Structural & Molecular Biology, Kampmann isolated and purified samples of the most fundamental building block of the NPC known as the Nup84 complex, which is composed of seven proteins. The entire NPC ¨C enormous by molecular standards ¨C consists of 30 different kinds of proteins. Focusing on the Nup84 complex, Kampmann used an electron microscope (EM) to take thousands of images of the complex in different states or conformations, which could reflect a role in the expansion and contraction thought to facilitate the passage of various sized molecules through the NPC. By computationally averaging these many different views, he reconstructed the first three-dimensional models of the Nup84 complex. Finally, based on prior work in the Blobel lab using X-ray crystallography to determine the exact atomic structure of individual proteins in the Nup84 complex, he plugged these proteins snugly into the EM structure.
"Because the nuclear pore complex is probably too big and flexible to determine its entire atomic structure by X-ray crystallography, I think this three-dimensional EM approach could be a big help in solving the whole thing," Kampmann says. "It allows us to put the crystal structures that we do have in context." Kampmann is applying the EM approach to other subunits in hopes of fleshing out the overall picture of one of the most mysterious machines in molecular biology. "Martin's data represent an important advance toward piecing together the structure of the NPC," Blobel says.
Given the central role of the nuclear pore complex in the most basic cell processes, defects in its assembly, structure and function can have lethal consequences. Its proteins have been associated with viral infection, primary biliary cirrhosis and cancer. An understanding of how the complex works could lead to treatments for these diseases, and also reveal the evolutionary coup that led to the gene-protecting structure found in every cell more complicated than the simplest single-celled microorganisms: the nucleus.
Brett Norman | 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
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For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
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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Mechanisms underlying dynamics of montane ecosystems and species in an era of climate variability and change
Climate Change Responses welcomes submissions to the thematic series on 'Mechanisms underlying dynamics of montane ecosystems and species in an era of climate variability and change'.
Alpine and subalpine ecosystems are globally recognized as being highly vulnerable to climatic shifts. Warming temperatures and shifts in precipitation are expected to effect extensive and possibly rapid changes to the structure, function, and composition of these high-elevation systems. These changes include an overall reduction in their area, large-scale alterations of physical processes, shifts in vegetation community boundaries, phenological shifts and changes in composition of plant and animal communities. Moreover, because species are often unique, specialized, poor dispersers and restricted in range, there are concerns that many will be unable to accommodate or adapt to new climatic regimes. Thus, many species may become more restricted in range and some could experience local extirpations.
Evidence abounds that changes in high-elevation systems have been and are continuing to occur. However, there are also many indications, from both paleontological and contemporary data, that climate shifts will not necessarily have uniform effects on alpine and subalpine biota. Species responses can be very heterogeneous, with range shifts occurring in some regions and species but not others, or changes in abundance being driven by interactions among several biotic and abiotic processes. Moreover, although few disagree that alpine and subalpine ecosystems will continue to change, these changes may not necessarily be driven directly or exclusively by climate. Rather, they may occur through various pathways as a result of indirect effects from multiple factors interacting with climate. These pathways are unlikely to lead to only a few simple uniform states, but rather to a number of alternative states. The key challenges, then, do not revolve around the question of whether change is happening; it is indeed already occurring. Instead, questions need to focus on sources of variability that could modify the rate, magnitude, and direction of change, at different levels of biological organization in high-elevation ecosystems.
The goal of this series is to focus on interactions between abiotic and biotic processes in high-elevation ecosystems. The manuscripts will focus on: (1) mechanisms of change; and, (2) relationships among animal communities, vegetation communities, and climate. By focusing on mechanisms, we will advance perspectives beyond what might happen, to the reasons why and how animals are being affected by climate, how these relate to adaptations to changes in climate and their habitat, and to how interactions such as herbivory and granivory could alter what are assumed to be inevitable changes in high-elevation vegetation communities.
Before submitting your manuscript, please ensure you have carefully read the submission guidelines for Climate Change Responses. The complete manuscript should be submitted through the Climate Change Responses submission system. To ensure that you submit to the correct thematic series please select the appropriate thematic series in the drop-down menu upon submission. In addition, indicate within your cover letter that you wish your manuscript to be considered as part of the thematic series on 'Mechanisms underlying dynamics of montane ecosystems and species in an era of climate variability and change'. All submissions will undergo rigorous peer review and accepted articles will be published within the journal as a collection.
Erik Beever, U.S. Geological Survey (Northern Rocky Mountain Science Center); Montana State University, USA
Toni Lyn Morelli, U.S. Geological Survey (Northeast Climate Science Center), USA
Robert C. Klinger, Western Ecological Research Center, USA
Submissions will also benefit from the usual advantages of open access publication:
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2017 Journal Metrics
88 days from submission to first decision
155 days from submission to acceptance
22 days from acceptance to publication
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By: ED Morgan
180 pages, Illus
The chemical study of insects has been growing for four decades, and with it an interest in how insects make their pheromones, hormones, defensive secretions, venoms, pigments and surface coverings. By investigating the biosynthesis of insects, one can gain a greater insight into the structure and function of insect compounds, into ways of disrupting biosynthetic reactions in pest species and how these pathways evolved.
The first textbook of its kind, this book amalgamates previously fragmented information and recent exciting developments in the field to provide a unique, concise chemical study of how insect substances are biosynthesised. It provides a comprehensive introduction to the ways that have been investigated, by which a great variety of insects, and some related arthropods, make their so-called secondary metabolites. Simpler biosynthetic pathways are explored before considering the experimental methods by which these studies are conducted. Consideration is also given to some of the plant substances which insects store or metabolize to their own use.
Abundantly illustrated with structures and reactions, and some beautiful photographs, Biosynthesis in Insects includes a series of problems and answers to facilitate and assess learning, making this unique look at biosynthesis in insects and their near relations ideal for students with some chemical background starting out on a study of insect substances. Researchers and academics will also welcome the amalgamation of previously scattered information. Includes an index of compounds and species, and lists for further reading.
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Microscopic roundworms (nematodes) live like maggots in bacon: They penetrate into the roots of beets, potatoes or soybeans and feed on plant cells, which are full of energy. But how they do it precisely was previously unknown. Scientists at the University of Bonn together with an international team discovered that nematodes produce a plant hormone to stimulate the growth of specific feeding cells in the roots. These cells provide the parasite with all that it needs. The results are now published in the journal "Proceedings of the National Academy of Sciences of the United States of America" (PNAS).
The beet cyst nematode (Heterodera schachtii) is a pipsqueak of less than a millimetre in length, but it causes huge yield losses in sugar beet. Not only are infected beets smaller than normal, but also they have an increasing number of lateral roots and experience a drastic decrease in sugar yield.
This makes the pest a talking point as a cause of the dreaded “beet fatigue”, especially in traditional sugar beet growing such as Bonn. To date, however, it was not clear how the nematodes stimulate the development of a nurse cell system inside the root, which they absolutely need as a food source.
It arises from the fact that cells divide increasingly, merge with each other and eventually swell. "For a long time it was speculated that plant hormones play a role in the formation of a nurse cell system in roots," says Prof. Dr. Florian Grundler from the Molecular Phytomedicine, University of Bonn. Since the nematodes lose their ability to move after penetrating into the roots, they are particularly dependent on the development of tumorous nurse cell system.
Pest uses degradation products of its metabolism
Together with scientists from Columbia (USA), Olomouc (Czech Republic), Warsaw (Poland), Osaka (Japan) and the Freie Universitaet Berlin, the researchers at the University of Bonn have used Arabidopsis thaliana as a model plant to discover that the beet cyst nematode itself produces the plant hormone cytokinin.
“The nematode has been able to employ a breakdown product of its own metabolism as a plant hormone to control the development of plant cells,” said lead author and research group leader Dr Shahid Siddique. The pest programmed the plant roots in beets to form a special nutritive tissue, which the nematode uses for its own growth.
The research team initially did not know whether the pest uses the hormone plants produce or whether it produces and releases the hormone itself. The scientists blocked cytokinin production in the plant - the nematode nevertheless continued to grow because it was not dependent on the plant-produced hormone.
Only when the agricultural experts blocked a special receptor at the docks to override the worm-produced hormone did they starve the pest, discovering that the hormone is important for the formation of the nurse cell system. “In this case, Heterodera schachtii cannot use its ability to produce cytokinin anymore, because a vital pathway was interrupted in the root cells,” explained Dr Siddique.
New options for plant breeding
Although this discovery is a result of basic research, it opens up new avenues in plant breeding. “On the one hand the result is an important contribution to the fundamental understanding of parasitism in plants, and on the other hand it can help to reduce the problem of cyst nematode in important agricultural crops,” said Prof Grundler. Now that an important mechanism had been found by the research, we are looking for an appropriate strategy to use these results specifically in resistance breeding.
Publication: A parasitic nematode releases cytokinin that controls cell division and orchestrates feeding site formation in host plants, Proceedings of the National Academy of Sciences (PNAS), DOI: 10.1073/pnas.1503657112
Contact for the media:
Prof. Dr. Florian Grundler
Johannes Seiler | idw - Informationsdienst Wissenschaft
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Other new alien species identified by the Conservation Biology Research Group
18 November 2016
The Niger Hind, Cephalopholis nigri, is a new alien fish species for the Mediterranean discovered by the Conservation Biology Research Group at the University of Malta.
This conservation research group led by Adriana Vella, PhD (Cambridge), has been actively working directly with fishermen and sea-users as part of the long-term research effort for monitoring and understanding the changes of local species and their marine environment. The recent discovery is already in press in the UK scientific peer-reviewed journal, Marine Biodiversity Records authored by Noel Vella, Ph.D and Sandra Agius Darmanin, MSc., apart from Adriana and it considers the morphological and genetic analyses of the first record of the Niger Hind, Cephalopholis nigri in the Mediterranean Sea.
In this conservation oriented research effort various maritime entities have been assisting, including the AFM, Transport Malta, fishermen, scuba divers and the NGO BICREF. The scientific members of this research team are all active in field and laboratory research themselves while they carefully investigate queries regarding unusual creatures or occurrences out at sea brought forward by sea-users. This sustains a mutually useful dialogue where fishermen, scuba-divers, swimmers, sailors may better understand the ongoing changes and the requirements for a healthy marine environment.
The research tools used to identify and understand the conservation status of local species are also being used to find out more about the changing biodiversity in Maltese waters. There is a serious concern that increasing number of new alien species may fast change local communities which needs to be dealt with responsibly focusing on local species at the centre of the knowledge gaining efforts. For this reason, these new scientific discoveries of alien species in the Mediterranean are added to the various other discoveries and efforts this active research group has been producing through the years while informing the public in general of ongoing long-term conservation investigative efforts.
While thanking all sea-users that sustain such conservation work, the conservation research group welcomes queries on further information by contacting: Adriana Vella on firstname.lastname@example.org and mob: 99429592 | <urn:uuid:02142b35-5a48-4087-af08-d29c75247a07> | 2.59375 | 447 | News (Org.) | Science & Tech. | 17.381986 | 95,616,553 |
Mapping Global Atmospheric CO2 Concentration at High Spatiotemporal Resolution
AbstractSatellite measurements of the spatiotemporal distributions of atmospheric CO2 concentrations are a key component for better understanding global carbon cycle characteristics. Currently, several satellite instruments such as the Greenhouse gases Observing SATellite (GOSAT), SCanning Imaging Absorption Spectrometer for Atmospheric CHartographY (SCIAMACHY), and Orbiting Carbon Observatory-2 can be used to measure CO2 column-averaged dry air mole fractions. However, because of cloud effects, a single satellite can only provide limited CO2 data, resulting in significant uncertainty in the characterization of the spatiotemporal distribution of atmospheric CO2 concentrations. In this study, a new physical data fusion technique is proposed to combine the GOSAT and SCIAMACHY measurements. On the basis of the fused dataset, a gap-filling method developed by modeling the spatial correlation structures of CO2 concentrations is presented with the goal of generating global land CO2 distribution maps with high spatiotemporal resolution. The results show that, compared with the single satellite dataset (i.e., GOSAT or SCIAMACHY), the global spatial coverage of the fused dataset is significantly increased (reaching up to approximately 20%), and the temporal resolution is improved by two or three times. The spatial coverage and monthly variations of the generated global CO2 distributions are also investigated. Comparisons with ground-based Total Carbon Column Observing Network (TCCON) measurements reveal that CO2 distributions based on the gap-filling method show good agreement with TCCON records despite some biases. These results demonstrate that the fused dataset as well as the gap-filling method are rather effective to generate global CO2 distribution with high accuracies and high spatiotemporal resolution. View Full-Text
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Jing, Y.; Shi, J.; Wang, T.; Sussmann, R. Mapping Global Atmospheric CO2 Concentration at High Spatiotemporal Resolution. Atmosphere 2014, 5, 870-888.
Jing Y, Shi J, Wang T, Sussmann R. Mapping Global Atmospheric CO2 Concentration at High Spatiotemporal Resolution. Atmosphere. 2014; 5(4):870-888.Chicago/Turabian Style
Jing, Yingying; Shi, Jiancheng; Wang, Tianxing; Sussmann, Ralf. 2014. "Mapping Global Atmospheric CO2 Concentration at High Spatiotemporal Resolution." Atmosphere 5, no. 4: 870-888. | <urn:uuid:ee9faf8f-8fd3-49d8-a55f-26140882b080> | 2.609375 | 545 | Academic Writing | Science & Tech. | 20.704571 | 95,616,554 |
The number 14 in carbon 14 dating text dating uk
The age of the carbon in the rock is different from that of the carbon in the air and makes carbon dating data for those organisms inaccurate under the assumptions normally used for carbon dating.
This restriction extends to animals that consume seafood in their diet.
This rules out carbon dating for most aquatic organisms, because they often obtain at least some of their carbon from dissolved carbonate rock.A team of researchers has derived the first theoretical equation to demonstrate that global ... Now that most consumers download and stream their movies and music, more and more CDs and DVDs will end up in landfills or be recycled.Thus carbon-14 has six protons and eight neutrons.) Carbon-12 is by far the most abundant carbon isotope, and carbon-12 and -13 are both stable.But carbon-14 is slightly radioactive: it will spontaneously decay into nitrogen-14 by emitting an anti-neutrino and an electron, with a half-life of 5730 years.
Search for the number 14 in carbon 14 dating:
Carbon dating is used to determine the age of biological artifacts up to 50,000 years old. | <urn:uuid:ebc4be22-d94b-4865-9c8f-d7e1aae8036b> | 3.28125 | 240 | Spam / Ads | Science & Tech. | 57.108908 | 95,616,568 |
When NASA's Terra satellite passed over Tropical Storm Ignacio on Sept. 1 it gathered cloud and wind data on the weakening storm.
Late on August 31 at 11 p.m. EDT the RapidScat instrument that flies aboard the International Space Station observed Ignacio's strongest winds surrounded the center of storm near 30 meters per second (108 kph/67 mph). Those winds weakened over the next 36 hours.
At 21:10 UTC (5:10 p.m. EDT) the MODIS instrument aboard Terra captured a visible image of Tropical Storm Ignacio well north of the Hawaiian Islands. As the storm weakened from a hurricane to a tropical storm, the eye was no longer visible.
At 11 a.m. EDT on September 2, there are no coastal watches or warnings in effect for Hawaii as Ignacio passing well north of the main Hawaiian Islands.
There was no eye visible on satellite imagery, but the center of the storm was indicated by a "warm spot" on infrared imagery that stood out from the colder cloud top temperatures of the thunderstorms surrounding Ignacio's center. Those thunderstorms, however, had weakened since the previous day.
The center of Tropical Storm Ignacio was located near latitude 26.1 north and longitude 157.1 west. That's about 335 miles (540 km) north of Honolulu.
Ignacio was moving toward the northwest near 12 mph (19 kph) and the storm is expected to turn to the north-northwest late on September 3. Maximum sustained winds were near 70 mph (110 kph) and slow weakening is expected starting on Thursday, September 3.
Rob Gutro | European Geosciences Union
Global study of world's beaches shows threat to protected areas
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NSF-supported researchers to present new results on hurricanes and other extreme events
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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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Everything you need to know about static code analysis
At Codacy, we know that testing your code is one of the most important parts of the entire software development lifecycle — that’s why we’re working every day to build the world’s best code analysis tool. One of the key characteristics of the product is static code analysis — in short, it’s the specific method we use to run tests on your code.
The term might not immediately ring a bell if you’re a beginning developer or feel like you need to brush up on your knowledge, we’ve got you covered. In this article we’ll take you through the basics of the term, explaining what it’s all about and why it’s such an important part of modern code review tools.
Static code analysis versus dynamic code analysis
When you’re talking about code review tools, it’s important to differentiate between the two most popular ways to go about it — and take a closer look at the reasons why you would want to use either of them.
On the one hand there’s static code analysis, a way for developers to test their code without actually executing it — this is called a non-runtime environment. Tools that use this method offer an incredibly efficient way to find programming faults and display them to developers. One of its main benefits is that errors can be picked up a long time before they end up causing havoc when the code is released or put live on a server. Static analysis is generally considered the more thorough way to perform code analysis, and it also has the potential to be the more economical option. If an error is caught during static code analysis — which can be done at an early stage — it’s relatively cheap to fix it, compared to an error that gets stuck in the system.
Then there’s dynamic code analysis, a way to test code while it’s being executed on a real or virtual processor. It’s especially effective for finding subtle defects or vulnerabilities, because it also looks at the code’s interaction with other databases, servers and services. Dynamic analysis definitely isn’t perfect, however, as it comes with quite some important caveats. For example, it’ll only ever find faults in the specific excerpt of the code that’s being executed – not the entire codebase. On the other hand, some of the errors that wouldn’t be found by static code analysis would show up clearly in a dynamic test, especially those related to parts of the source code that rely on external services.
To achieve the highest possible level of test coverage, it’s recommended to combine the two methods. Together, static and dynamic code analysis are often referred to as ‘glass-box testing’, because of their ability to have a peek inside the ‘box’ that’s the codebase.
Automating code review with static code analysis
Although static code analysis can be done manually, it can take lots of time when dealing with large amounts of code. Even if you have access to a sizable team of developers to peer review each other’s work, the results would be much more prone to error and false positives.
Fortunately, automated analysis is here to save the day — it’s a much faster and easier way to consistently check your code for errors. It’s also more accessible, because it doesn’t rely on the developer to have the deep knowledge that’s required to perform a proper analysis. Instead, it combines a large, predefined set of common and less-common errors with intelligent algorithms to efficiently track them down. This way, a great tool offering automated static code analysis is able to find certain bugs in a matter of seconds, while it would take a human auditor hours or days.
When the source code analysis is complete, the software then gives comprehensive feedback by displaying all security flaws, code style violations and other metrics to the user. This creates an actionable overview for the developer, who can immediately get to work on fixing their mistakes.
A modern tool for automated static code analysis
Automated static code analysis can be an incredibly powerful tool — it enables developers to write better code that’s free of security vulnerabilities, works without a hitch, is up to coding standards and respects best practices.
Codacy is a cutting-edge static analysis tool that’s trusted by thousands of developers at world-class companies like Adobe and PayPal. It offers all the benefits of automated reviews, wrapped up in a platform that’s as elegant as it is powerful. With customizable code analysis, intelligent project quality evaluation, extensive feedback on your code and easy integration in your existing workflow, it offers a comprehensive suite of automated tools for programmers that care about shipping top-notch code in any programming language. Give it a spin today by signing up for a free trial. | <urn:uuid:4f09a7b6-3fad-43fb-8cc9-2d27b3424029> | 2.578125 | 1,012 | News (Org.) | Software Dev. | 32.664887 | 95,616,605 |
Determination de l’oxygene dans le sodium par activation au moyen de protons
The method described may be used to measure traces of oxygen in sodium, whatever the potassium content is. In addition, if the sample is very pure, a non-destructive analysis is possible. Experience shows that nitrogen or boron can be determined in the same way if one of these elements is predominant with respect to the others.
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+44 1803 865913
Edited By: Howard T Odum
Much of the convenience of modern life resides in sheet metal, the cowling shield of most machines and appliances. However, the load that this takes off human shoulders has to be carried elsewhere, and the Earth has borne the burden. Many of us woke up to the environmental cost when over a century of industrialization finally surpassed the capacity of nature to assimilate it.International in scope, Heavy Metals in the Environment: Using Wetlands for Their Removal discusses wetland functions and heavy metal contamination. It addresses such questions as: Can systems powered by sunlight handle toxins more effectively than systems running on fossil fuel? At what scale and by what means do we define efficiency? These questions resonate increasingly with a number of global challenges.As inescapable as climate change, you can no longer avoid airborne toxins, acid rain, and polluted water by moving away from them. When the time comes to rely less on fossil fuel-based technology, how will we clean up the aftermath of toxic misadventures?Written by a leader in the growing field of ecological engineering, Heavy Metals in the Environment: Using Wetlands for Their Removal presents scientific studies that illustrate how natural systems use wetlands to adapt to changes in the ecosystem. It focuses primarily on lead, one of the first materials used by developing civilizations and a metal used heavily in the industrial era. The goal: to achieve a better understanding of how natural systems use wetlands to adapt to wastes.
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The genes, called E2F7 and E2F8, are the least understood members of a family of genes that play a fundamental role in animal development. Members of this family are also involved in cancers of the breast, bladder, stomach and colon.
This animal study showed that complete loss of the two genes causes massive cell death and is lethal in developing embryos.
It also showed that the two genes prevent this cell death largely by suppressing the activity of another member of the family, called E2f1. This third gene is known to play an important role in triggering programmed cell death, or apoptosis, in embryos.
The findings by researchers at the Ohio State University Comprehensive Cancer Center are published in the Jan. 15 issue of the journal Developmental Cell, with an accompanying commentary.
“Until now, almost nothing was known about the function of these two genes in animals,” says principal investigator Gustavo Leone, an associate professor of molecular virology, immunology and medical genetics at Ohio State’s Comprehensive Cancer Center.
“Our study not only shows that both these genes are critical for embryonic development, but also how members of this gene family work together to regulate cell survival and proliferation.”
Leone and his colleagues used mice that were missing either E2f7 or E2f8, or both genes, and mice missing both genes and the E2f1 gene.
Their experiments showed that embryos survived, and massive cell death was prevented, if they had at least one copy (of the normal two) of either of the two genes.
When the two genes were entirely missing, however, massive cell death and other problems occurred that were lethal before birth. On the other hand, embryos that were completely missing both genes and missing the E2f1 gene, did not show the massive cell death, although they also died before birth. “This of course means that E2f7 and E2f8 are doing more than just regulating cell death, and we are now exploring new avenues of their function,” Leone says.
“Overall,” he says, “our findings indicate that these two genes are essential for embryonic development and for preventing widespread cell death, mainly by targeting the E2f1 gene.”
Darrell E. Ward | EurekAlert!
O2 stable hydrogenases for applications
23.07.2018 | Max-Planck-Institut für Chemische Energiekonversion
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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Glaciers exist where the annual temperature remains cold enough to allow snowfall to accumulate for an extended period of time and where conditions allow subsequent metamorphosis to ice. Glacial ice forms expansive continental ice sheets in the polar regions, (e.g., in Antarctica and Greenland), and at lower latitudes, ice fields (valley or alpine glaciers) and ice caps (if a volcano or mountain range is completely glaciated) exist globally at high altitude. Temperate glaciers comprise 1.5×107 km2) and contain ~75% of the freshwater on Earth (Paterson 1994). The Antarctic ice sheet alone contains ~90% of the planet's ice and, if melted, would result in a sea level rise of ~65 m (The National Snow and Ice Data Center; http://nsidc.org/).
Mendeley saves you time finding and organizing research
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In this section, thought to talk about HTTP-Client usage in angular and how its different from existing HTTP Module. It has RxJS Observable-based API. It means that the multiple calls to the HTTP module will return an observable, which we need to subscribe.
- If we don’t subscribe to these observables, it won’t work.
- If we subscribe multiple times to these observables, multiple HTTP requests will be triggered.
- If HTTP request is successful, it will emit only one value and then complete
- If HTTP request fails, then these observables will emit an error.
Here, in the application, we need to refer
HttpClientModule like shown below.
And corresponding HTML
Here, Its a very simple code. Here, I am just making a request to URL and flushing the incoming value on the page. Here, you can notice that http get method returns one observable. Here, I am also mapping incoming value with my interface just for making it type compliant and with returning observable. Having said, when I click on the button, it will fetch the posts like shown below.
async pipe will subscribe to the HTTP observable, and it’s that implicit subscription that triggers the HTTP request. Now, we can send filter with request to filter data as required.
Below is the modified call.
Having said that, it will produce the following output.
Here, I filtered it by userId 7. This is fine, but think of building complex query. In that case, above params approach doesn’t work well. In order to fix that kind of scenario we can make use of HttpParams() like shown below. Here, we can build chain of HTTP-Headers as well. This is because
HTTPParams are immutable, and its API methods do not cause object mutation
This will also produce the same result. We also have the support of HttpHeaders. This utility heavily used in terms of authentication. Let’s imagine we want to send a request that can only be performed by currently logged in user. In that case, we can JWT with auth details in the header and then server will decode this token to validate whether the user has permission to access the resource or not? Here, I have modified the code for headers.
Now, when I click on the button, then in network tab in chrome developer tool, we can see the below result.
Now, let’s create a Post request. Below is the finished snippet with Post as well.
And corresponding markup change,
Having done above change, When I click on New Post button, it will print the following result. One of the most powerful features of HTTP-Client is, we can use any rxjs operator on this. Let’s suppose we want to filter down the data further. Then, we can do something like
Having said that, when I check the output, it will print like
Now, let’s suppose, when I try to hit an endpoint which actually doesn’t exist, in that case, below snippet will try to reach the endpoint atleast 5 times and then it will print the error message like shown below.
Now, it will give below result.
Now, let’s see some other important use cases of this. Now, let’s say, we would like to make parallel requests to different endPoint and then want to combine the result. Below is the finished code for the same.
And corresponding markup looks like shown below.
With the above change in place, When I click on Parallel Request button, it will print the following values in console.
Now, let’s see how to do HTTP Request in sequence and use the response of first sequence to create the second request. One way of doing this is via switchMap operator. Below is the finished code for the same.
You can use something like shown above. Another new feature available in the new HTTP client is HTTP Interceptors. An HTTP Interceptor allows us to add generic functionality to our HTTP requests. Interceptors are ideal for cross-cutting concerns like for example adding an authentication token header. Below is the example for the same.
This is normal example of angular injectable service. Here, we are injecting Authentication Service which has the access of authentication token. The intercept method takes two arguments; request and handler. next.handle method needs to be called to continue the interceptor chain and for the HTTP Request to be made. It returns an Observable and then its returned by intercept method. The request object is immutable, hence if we want to modify the request header, we need to clone the same and then we can create modified copy of the same. The cloned request will have new HTTP header
X-CustomAuthHeader. In order to activate this interceptor and apply it to any HTTP request made using the HTTP client, we need to configure it in our application module by adding it to the
HTTP_INTERCEPTORS multi-provider as shown below.
Last but not least, it has also given progress events. To receive these events, we need to configure like shown below.
With this, I would like to wrap this post. I hope you would have enjoyed this post. Thanks for joining me.
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Jun. 25, 2018—The device is from the lab of Professor Michael Goldfarb, perhaps best known for working on a bionic leg with shark attack victim Craig Hutto and later developing the Indego exoskeleton.
Jun. 4, 2018—Humans aren't the only animals who can learn vocal communication from others. By studying the process in zebra finches, we may better understand how it works in humans, too.
May. 23, 2018—Imagine a box you plug into the wall that cleans your toxic air and pays you cash. That's essentially what Vanderbilt University researchers produced after discovering the blueprint for turning carbon dioxide into the most valuable material ever sold – carbon nanotubes with small diameters.
Apr. 30, 2018—Engineer Dan Work says his promising research shows adding autonomous vehicles to roadways could end the stop-and-go traffic that drives commuters insane.
Apr. 23, 2018—How a bacteria hijacked insect fertility remained a mystery for five decades, until Associate Professor of Biological Sciences Seth Bordenstein and his team helped solve it.
Jan. 25, 2018—A dozen Vanderbilt students went on a monthlong science adventure of a lifetime, studying super-eruptions, glaciers and earthquakes in New Zealand.
Nov. 29, 2017—The first study to actually count the number of cortical neurons in the brains of a number of carnivores, including cats and dogs, has found that dogs possess significantly more of them than cats.
Nov. 2, 2017—Sinead Miller was headed for the Olympic games. Now, thanks to a Department of Defense grant to find new sepsis treatments, the Vanderbilt Ph.D. has developed a device that cleans the blood.
Aug. 20, 2017—A new study has found that sugars in mother's' milk do not just provide nutrition for babies but also help protect them from bacterial infections.
Aug. 1, 2017—"Performance-boosting super suit" hidden under clothing can be activated by a double tap to save users' backs.
Jul. 24, 2017—Vanderbilt University engineers find existing human protein is ideal carrier for powerful molecules that can signal tumors to self-destruct. | <urn:uuid:18164d06-19f5-444c-9afc-6938a3a2aa2f> | 2.6875 | 448 | Content Listing | Science & Tech. | 57.925702 | 95,616,646 |
Quantum Mechanics with Basic Field Theory Hardback
Students and instructors alike will find this organized and detailed approach to quantum mechanics ideal for a two-semester graduate course on the subject.
This textbook covers, step-by-step, important topics in quantum mechanics, from traditional subjects like bound states, perturbation theory and scattering, to more current topics such as coherent states, quantum Hall effect, spontaneous symmetry breaking, superconductivity, and basic quantum electrodynamics with radiative corrections.
The large number of diverse topics are covered in concise, highly focused chapters, and are explained in simple but mathematically rigorous ways.
Derivations of results and formulae are carried out from beginning to end, without leaving students to complete them.
With over 200 exercises to aid understanding of the subject, this textbook provides a thorough grounding for students planning to enter research in physics.
Several exercises are solved in the text, and password-protected solutions for remaining exercises are available to instructors at www.cambridge.org/9780521877602.
- Format: Hardback
- Pages: 858 pages, 230 exercises
- Publisher: Cambridge University Press
- Publication Date: 03/12/2009
- Category: Quantum physics (quantum mechanics & quantum field theory)
- ISBN: 9780521877602 | <urn:uuid:1190e3a5-b3c1-418a-a757-575e8f680144> | 2.53125 | 275 | Product Page | Science & Tech. | 16.623814 | 95,616,650 |
A bee collects pollen from ragwort flowers in Ladywell park in London. As flowers bloom, butterflies, moths, bees and other insects get busy pollinating, and themselves turn into food for predators such as bats – all playing their part to maintain a healthy ecosystem. Photograph: Dan Kitwood/Getty Images
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Some students have noticed and wondered why there were so many fireflies this year. To answer their questions, the Gazette went to Julie Hagelin, Assistant Professor of Biology who conducts research on animal behavior, and she referred us to Sara Lewis, a Professor of Biology at Tufts University who studies fireflies.
Professor Lewis explained that fireflies spend between one to two years underground as larvae, feeding mainly on earthworms. “A major source of larval mortality would be drought occurring in the fall or spring, so adult firefly populations may have benefited from the wet spring and summer we had this past year,” she wrote in an e-mail. So, the rainy weather of earlier this year is a likely factor in the firefly population boom that was witnessed and appreciated all over Swarthmore’s campus.
Got other phosphorescing/burning questions? Ask The Gazette: dailygazette [at] swarthmore [dot] edu | <urn:uuid:96aa37bd-8e5b-4364-b6c3-1ce9a7d094a7> | 3.0625 | 196 | News (Org.) | Science & Tech. | 31.461847 | 95,616,682 |
Using a new molecular genetic technique, scientists have turned procrastinating primates into workaholics by temporarily suppressing a gene in a brain circuit involved in reward learning. Without the gene, the monkeys lost their sense of balance between reward and the work required to get it, say researchers at the NIHs National Institute of Mental Health (NIMH).
"The gene makes a receptor for a key brain messenger chemical, dopamine," explained Barry Richmond, M.D., NIMH Laboratory of Neuropsychology. "The gene knockdown triggered a remarkable transformation in the simian work ethic. Like many of us, monkeys normally slack off initially in working toward a distant goal. They work more efficiently – make fewer errors – as they get closer to being rewarded. But without the dopamine receptor, they consistently stayed on-task and made few errors, because they could no longer learn to use visual cues to predict how their work was going to get them a reward."
Richmond, Zheng Liu, Ph.D., Edward Ginns, M.D., and colleagues, report on their findings in the August 17, 2004 Proceedings of the National Academy of Sciences, published online the week of August 9th.
Jules Asher | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
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NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
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Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Invalidating iterators c Free teen cam chat
You can find "how-to" information in the Yocto Project Development Manual.
The Yocto Project is an open-source collaboration project whose focus is for developers of embedded Linux systems.
No compilation is needed, as this is a header-only library.
The installation consist in copying the sparsepp directory wherever it will be convenient to include in your project(s).
F, Sp, Su Course designed for transfer and part of the TN Transfer Pathways.
The build system, which is based on the Open Embedded (OE) project and uses the Bit Bake tool, constructs complete Linux images for architectures based on ARM, MIPS, Power PC, x86 and x86-64.
This manual provides reference information for the current release of the Yocto Project.
This manual is best used after you have an understanding of the basics of the Yocto Project.
Also, an emphasis on managerial and cost accounting for making sound business decisions.
(Prerequisite: ACCT 1010; a grade of C or better is strongly recommended in ACCT 1010) F, Sp Course designed for transfer and part of the TN Transfer Pathways.
The function template argument is a bidirectional iterator type that points to elements. | <urn:uuid:7768a82f-2bfe-4562-a813-3472d2a0b67d> | 2.515625 | 268 | Truncated | Software Dev. | 45.630516 | 95,616,711 |
While scientists and aurora spotters marvel at the explosions on the Sun, everyone responsible for the hundreds of satellites that serve human needs, from weather observations to car navigation, wishes that these potentially damaging events were more predictable.
Artists impression of SOHO spacecraft
A blast of gas from the Sun can buffet the Earths magnetic field
So do the astronauts aboard the International Space Station, who recently had to shelter from energetic particles flung out by the most powerful solar flare ever recorded. Now, from space observations of the Sun going back more than 20 years, experts are beginning to make more sense of the solar outbursts.
Apparently random events turn out to be signs of the Sun’s diligent housekeeping. It keeps sweeping away, out into space, untidy magnetic fields created by sunspots and other contortions in its atmosphere. The climax comes in a busy period of spring cleaning after the count of sunspots has peaked, every 11 years. It leaves the Sun with its main magnetic field completely overturned, and its north and south magnetic poles swapped around.
Bernhard Fleck | ESA
Computer model predicts how fracturing metallic glass releases energy at the atomic level
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The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
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Persisting Colors and Other Settings with Visual Basic
Application Security Testing: An Integral Part of DevOps
Persisting information means to save information (of any type) and to retrieve it from the location to which it has been saved. With today's article, I will show you two ways to save colors. Now, the first question that pops into your head might be: Why? Well, the answer is simple. People like saving settings such as the location and size of a particular form, but they also like to save colours. This just adds a little professional touch in rounding off your application.
As I mentioned earlier, persistence means to save and retrieve information. Where can you save information? Anywhere on the computer… No, that is a sick joke—because that is obviously not what you meant. You can save information in the system Registry, or, you can use the built-in Application Settings of your application. Obviously, there may be more, but this article serves only as an introduction, or a nudge in the right direction. For more information about persisting information, have a read through this article.The Registry stores lots of application settings. This is usually small pieces of text (actually any data, but up to a point) that would be senseless dedicating a whole file to it. For more information regarding the Registry, have a look through this (very old) article of mine.
Application settings is a nice little handy storage space also for small pieces of data. This has become the preferred method to store user-specific or even application-specific settings. More information regarding Application.Settings can be found here.
The purpose of today's project is simply to store a color value into either the Registry or Application.Settings. There isn't much of a design. For interest's sake, design your Form in your Windows Forms application to resemble Figure 1.
Figure 1: Our Design
Add a ColorDialog to your project as well.
Before I continue to the code, I must first show you how to set up your Applications.Settings. Don't worry; it is really not complicated at all. There are two ways:
- Through the use of the Properties Window
- Through Project properties
To add a custom setting, such as a color, follow these steps:
- Select the form.
- Open the Properties Window, if not already open, by pressing F4.
- Expand the ApplicationSettings item on top of the Properties list.
- Click the ellipses button next to PropertyBinding. This will show the following screen:
Figure 2: Property Binding
- Select BackColor from this list, and click the blue New link that is displayed.
- Give it a name, scope, and a default value, such as shown in Figure 3.
Figure 3: Closeting
- Click OK.
- Notice the BackColor Property inside the Properties Window. This indicates that it is a custom application setting, and that the color you see in design time might not be the color you will see when the app starts because it relies on the color specified by the user.
Figure 4: BackColor property
To Add a setting through the Project Properties, follow these steps:
- Click Project.
- Click Project Name Properties—where Project name is your project's name.
- Click Settings.
- Fill in a Name, Type, and the setting as shown in Figure 5:
Figure 5: Project Properties
Let's get down to business!
Although due to the fact that you have already set the BackColor property in Application.Settings, it will be saved automatically, but sometimes you will need to load the saved setting, especially when a user is involved. Add the next code behind the Button1 Click event:
Private Sub button1_Click(sender As Object, _ e As EventArgs) Handles Button1.Click Dim ColSet As New Color ColSet = My.Settings.ColorSettings Me.BackColor = ColSet End Sub
This code simply loads the color that was stored and makes the form's backcolor the saved color.
Add the following code:
Private Sub Button3_Click(sender As Object, e As EventArgs) _ Handles Button3.Click If (ColorDialog1.ShowDialog() = _ Windows.Forms.DialogResult.OK) Then Me.BackColor = ColorDialog1.Color Application.UserAppDataRegistry.SetValue _ ("Colour", ColorDialog1.Color) End If End Sub
Now, let's play with the Registry.
Add the following code:
Private Sub Button3_Click(sender As Object, e As EventArgs) _ Handles Button3.Click If (ColorDialog1.ShowDialog() = _ Windows.Forms.DialogResult.OK) Then Me.BackColor = ColorDialog1.Color Application.UserAppDataRegistry.SetValue("Colour", _ ColorDialog1.Color) End If End Sub
This saves the actual color value into the Registry. This is not the name; this is the physical color value. Now, don't let the preceding code fool you. Loading it from the Registry is not as easy, as in the next code segment:
Private Sub button2_Click(sender As Object, e As EventArgs) Handles Button2.Click 'REGISTRY Dim strCol As [String] Dim blnLoaded As Boolean = False Dim colStoredColor As Color Dim A As [String] = "" Dim R As [String] = "" Dim G As [String] = "" Dim B As [String] = "" Dim strLength As Integer strCol = Application.UserAppDataRegistry.GetValue _ ("Colour").ToString() Dim strColorName As [String] = "" Dim ArrColor As [String]() ArrColor = strCol.Split(",".ToCharArray()) A = strStringRight(ArrColor(0), _ ArrColor(0).IndexOf("=") + 1) R = strStringRight(ArrColor(1), _ ArrColor(1).IndexOf("=") + 1) G = strStringRight(ArrColor(2), _ ArrColor(2).IndexOf("=") + 1) strLength = ArrColor(3).Length - _ ArrColor(3).LastIndexOf("]") B = strPartRight(ArrColor(3), _ ArrColor(3).IndexOf("=") + 1, strLength) blnLoaded = True If blnLoaded = True Then colStoredColor = _ System.Drawing.Color.FromArgb(Convert.ToInt16(A), _ Convert.ToInt16(R), Convert.ToInt16(G), _ Convert.ToInt16(B)) Else colStoredColor = Color.FromName(strColorName) End If Me.BackColor = colStoredColor End Sub
This code basically reads the color value. Then, it breaks the string apart with the use of the following two functions (which is just a simpler way of breaking strings apart with SubString):
Public Shared Function strStringRight(strInput As String, _ intStart As Integer) As String Dim result As String = strInput.Substring(intStart) Return result End Function Public Shared Function strPartRight(strInput As String, _ intStart As Integer, intLength As Integer) As String Dim result As String = _ strInput.Substring(intStart, intLength) Return result End Function
As I mentioned, the original string gets broken up. It basically gets the Alpha, Red, Green, and Blue values. Once all those values have been read, it is easy to assemble the physical color again via the use of the built-in Convert.ToInt16 methods.
I have attached a working sample.
I hope you have enjoyed today's article. Until next time, cheers!
Hannes du Preez is a Microsoft MVP for Visual Basic for the seventh year in a row. | <urn:uuid:42bc633a-e840-44c1-80aa-fd202cba661c> | 2.765625 | 1,678 | Personal Blog | Software Dev. | 57.403428 | 95,616,737 |
- Meeting report
- Open Access
Crops in all shapes and sizes
© BioMed Central Ltd 2008
Published: 11 September 2008
A report of the joint American Society of Plant Biologists/Sociedad Mexicana De Bioquímica meeting held in Mérida, Mexico, 26 June-1 July 2008.
A recent conference of plant biologists held in Mexico brought together scientists working on a wide range of species, from the model organism Arabidopsis thaliana to crops such as maize, tomato and rice. Appropriately for the locale, research relevant to major Central and South American crops was conspicuous. A few of the highlights in the areas of maize and tomato genetics and plant computational biology are reported here.
Maize genomics, genetics and epigenetics
Maize (corn, Zea mays L.) was domesticated from a species of wild teosinte, the common name for a group of annual and perennial species of Zea native to Mexico and Central America. Phylogenetic evidence suggests that maize arose from a single domestication event that occurred in Mexico about 9,000 years ago and which gave rise to a group of ancient landrace varieties. As the main center of origin and domestication, Mexico has the largest diversity of maize genetic resources. John Jones (Washington State University, Pullman, USA) presented evidence from fossilized pollen suggesting that the ancient farmers of San Andrés Tabasco in southern Mexico were cultivating an early form of maize about 7,300 years ago, 1,200 years before any previous archeological evidence of maize cultivation. He suggested that, in addition to serving as an ancestral food source, maize may have played a role as a driver of cultural development.
Despite the importance of selection-dependent bottleneck effects that drastically reduced genetic diversity, most maize genes have retained high levels of nucleotide diversity compared with other cereals. Erik Vollbrecht (Iowa State University, Ames, USA) presented work on the ramosa1 locus (ra1) showing that during the domestication of maize from teosinte, this locus experienced positive selection, as indicated by low ra1 nucleotide variability in both maize landraces and modern inbreds. ra1 encodes a putative C2H2-type zinc finger transcription factor that is unique to the Andropogoneae (the large grass tribe that includes maize and sorghum), and Vollbrecht suggested that the gene originated coincidentally with the evolution of a specialized short-branched spikelet pair distinctive of maize and its close relatives.
Maize is an ideal model plant in which to study the epi-genetic basis of phenotypic variation. Paramutation is an epigenetic phenomenon that results in the establishment of meiotically heritable expression that depends on the ability of specific DNA sequences to communicate in trans. Vicki Chandler (University of Arizona, Tucson, USA) reported that paramutation at the maize b1 locus is mediated by seven unique 853 bp non-coding tandem repeats that are necessary for this trans communication. Transcription of these repeats into small interfering RNAs (siRNAs) depends on mediator of paramutation 1 (mop1), a gene encoding an RNA-dependent RNA polymerase most similar to RDR2 in Arabidopsis. Chandler has strikingly found that the presence of siRNAs corresponding to tandem repeats in non-para-mutagenic individuals indicates that the siRNAs are involved in, but not sufficient for, paramutation, opening up the possibility of new discoveries about the basis of large-scale genomic information.
Palomero Toluqueño is an ancestral popcorn landrace with one of the smallest genomes among Mexican maize. One of us (J-P V-C) described progress in sequencing this genome, undertaken to explore landrace genomic diversity and to complement the sequencing of the inbred maize line B73 by the Maize Genome Sequencing Consortium. The total Palomero Toluqueño sequence generated represents coverage of approximately 3× the full genome and 20× the gene-enriched regions. Structural and functional analysis reveals a large number of hitherto unreported genes, suggesting that the ancient landraces contain a large pool of unexplored genetic diversity. This diversity should be potentially useful for generating new crops as well as for the study of the evolution and domestication of maize and other cereals.
Molecular mechanisms of tomato fruit morphology
Edible fruits are markedly diverse in size and shape. Breeding and mutation analysis in tomato have resulted in a diverse collection of germplasm, which provides a rich resource for studies on fruit morphology. Fruit morphological changes occur during ovary formation and/or during fruit formation, and so tomato varieties with different-shaped fruits can give insights into these developmental processes. Esther Van Der Knaap (Ohio State University, Columbus, USA) described the work of herself and colleagues on the mechanisms underlying tomato shape, and reported the identification of the gene SUN, one of the major genes controlling the elongation of tomato fruit. SUN was positionally cloned and found to encode a member of the IQ67 domain family. Van Der Knaap reported that the sun mutation responsible for the elongated shape of some tomatoes is the result of an interchromosomal duplication mediated by a retrotransposon - an unusual 24.7-kb gene duplication event mediated by the long-terminal repeat retrotransposon Rider. This event resulted in a new genomic context that increased SUN expression relative to that of the ancestral copy, culminating in an elongated fruit shape. This discovery shows that retrotransposons may be a major driving force in genome evolution and gene duplication, resulting in phenotypic changes in plants.
Despite the fact that the tomato genome sequence is not yet complete, the release of partial information by the Tomato Genome Consortium http://www.sgn.cornell.edu, together with extensive genetic data and new tools for functional genomics, has allowed significant advances in this model crop. Fernando Carrari (Instituto Nacional de Tecnología Agrícola, Buenos Aires, Argentina) and his colleagues combine genetic, genomic and metabolomic tools to dissect genetic determinants of quantitative trait loci affecting the chemical composition of tomato fruit. Carrari reported work using metabolic profiling and phenotyping of a collection of interspecific introgression lines to identify quantitative metabolic loci (QML) distributed across the tomato genome. The physical mapping of the QMLs is being addressed by using genome sequence information, an integrated analysis of metabolite and transcript levels during fruit development. Cararri reported that five genomic regions have been screened in detail and 127 candidate genes for regulation of metabolism during fruit ripening have been found. Candidate genes are being evaluated by a combination of virus-induced gene silencing and transgenesis. An integrated view of tomato fruit metabolism will help to uncover traits and targets with potential for improving fruit composition.
Computational challenges for the plant sciences
In the post-genomic era, data integration, analysis and interpretation are major factors limiting advances in biological research. Fortunately, a new generation of scientists well versed in both computational and experimental aspects of plant biology is rising to the challenge. Seung Rhee (Carnegie Institution, Stanford, USA) presented a new bioinformatics approach based on gene function correlation networks, developed in collaboration with Insuk Lee, to identifying genes that code for enzymes catalyzing the 'missing' steps in known metabolic pathways. On the basis of these predictions, her group chose 18 genes for experimental validation, and, in collaboration with other laboratories in the plant metabolomics consortium NSF2010 Metabolomics http://www.plantmetabolomics.org, determined the meta-bolomic profiles of 18 Arabidopsis lines carrying homozygous knockout mutations in these genes. The different mutants showed distinct alterations in their metabolomic profiles, and mapping the altered compounds in each mutant line back to the relevant metabolic pathway enabled the bioinformatics-derived predictions to be validated.
Computational modeling has also been applied to the mechanisms underlying the characteristic grain pattern of wood, which is determined by the orientation of cells in the vascular cambium. Grain pattern remains approximately constant for a tree's life, but can reorient in response to injury. This reorientation response is critical to the health of the tree as the grain direction determines the movement of water and assimilates in the stem. There are two competing hypotheses to explain wood-grain patterning: one proposes that the orienting signal is mechanical strain in the cambium; the other that it is a concentration gradient of the plant hormone auxin in the plane of the cambium. Eric Kramer (Bard College at Simon's Rock, Great Barrington, USA) described a computer model developed by his group that supported the second hypothesis by providing quantitative predictions of auxin concentrations and their correlation with grain pattern in Populus after injury. Their model was validated by experimental measurements of auxin concentrations around an injury site in Populus.
One of us (RAG) presented the new software platform VirtualPlant http://www.virtualplant.org, designed in collaboration with researchers at New York University. VirtualPlant enables the visualization, integration, and analysis of genomic data from a systems-biology perspective and simplifies the use of mathematical and statistical methods to help summarize and quantify the data. As proof of principle, VirtualPlant was used to predict the key transcription factors that regulate Arabidopsis gene networks in response to organic nitrogen (for example, glutamic acid). One predicted network was validated, showing that regulation of the expression of the master clock-control gene CCA1 by glutamine or a glutamine-derived metabolite directly regulates the expression of the key nitrogen-assimilatory genes. This work also discovered unexpected connections between nitrogen metabolism and the circadian clock in Arabidopsis. Regulation of CCA1 by organic nitrogen signals may represent a novel input mechanism for nitrogen nutrients to affect plant circadian clock function.
In the age of genomics, collaboration is key to successfully addressing outstanding questions in plant biology. The new iPlant Collaborative project http://www.iplantcollaborative.org presented by Rich Jorgensen (University of Arizona, Tucson, USA) is likely to play a key role in advancing plant sciences in the years to come. This 5-year $50-million program funded by the US National Science Foundation aims to develop an international cybercommunity of plant biologists, computational specialists and other disciplines to enable new conceptual advances in plant science. iPlant will initially provide services through a small, committed centralized core, and will gradually become distributed throughout the community. Jorgensen stressed that iPlant is "by, for and of the community", and the problems addressed through it must be driven by specific, compelling, and tractable 'grand challenges' that serve the entire breadth of the plant sciences. Plant researchers around the world are encouraged to put forward proposals and participate in the project.
Research and travel is funded by Millenium Nucleus for Plant Functional Genomics (P006-09-F) to RG. | <urn:uuid:28f6ebb8-451d-48e8-9314-cd9530b73fe0> | 2.8125 | 2,282 | Academic Writing | Science & Tech. | 11.640071 | 95,616,758 |
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Language: Russian with English summary and scientific nomenclature
This volume presents data on the distribution, habitats, phenology, food plants, variation, morphology and population levels of 121 species of butterfly, which are found in the territory of the European North-East of Russia. The zoogeographical structure of the butterfly fauna is determined. Hypotheses about the ways in which the lepidopteran fauna formed are offered. The book is intended for entomologists, zoologists, ecologists and students.
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The role of vorticity in 3D magnetic field annihilation
We show that magnetic field annihilation depends strongly on the behaviour of the vorticity and is quite different in 2D and 3D. In 3D the vorticity can be increased locally by the stretching of vortex lines (an effect that is absent in 2D). This leads to the onset ofcellular flow at quite low vorticities and the fragmentation of the simple current sheet.
Key wordsMagnetohydrodynamics Reconnection Magnetic Annihilation Vorticity
- Brandt, P.N., Scharmer, G.B., Ferguson, S., Shine, R.A., Tarbell, T.D., and Title, A.M.Nature, 335:238–240, 1988.Google Scholar
- Jardine, M., Allen, H.R., Grundy, R.E., and Priest, E.R.J. Geophys. Res., 97: 4199–4208, 1992.Google Scholar
- Jardine, M., Allen, H.R., and Grundy, R.E.J. Geophys. Res., 1993. in press.Google Scholar | <urn:uuid:4f7328c1-3eb6-4dfa-8f8c-3416e03a2ef7> | 2.546875 | 248 | Academic Writing | Science & Tech. | 81.426349 | 95,616,770 |
Any material or substance, which even in normal use, poses a risk to health, safety, property or the environment. Hazardous materials are broken down into nine primary classes by the United Nations, the USDOT, IATA and other regulatory bodies for the purposes of the placarding and identification the hazards of shipments.
the conclusion that it is impossible to know simultaneously the absolute exact position and the absolute exact speed of a particle such as an electron. The more precisely the position is known of a particle at a moment in time, the less precisely can its speed be determined. Conversely the more precisely the exact speed of a particle is known, the less precisely its position can be known. Werner P. Heisenberg, a German physicist, developed this principle from his work with quantum mechanics. He was awarded the Nobel Prize in physics in 1932 for his brilliant work.
As a side note, Star Trek fans will every now and then hear the crew refer to the "Heisenberg compensator" in the transporter pads. This is the writer's nod to this principle and the problems it would create for actually being able to teleport something they way they do in the Star Trek series.
A mixture or material consisting of more than one substance. The earth's atmosphere is heterogeneous in that it typically consists of 20.7% oxygen, 78% nitrogen, 0.93% argon and 0.03% CO2 with other gasses making up the remaining percentage. Heterogeneous is Latin for "different kinds".
A substance or material that contains only one kind of compound or one element. Homogeneous is Latin for "the same kind". An example of a homogeneous substance would be pure water, which only contains the compound H2O or pure table salt that only contains the compound NaCl.
A viscous polysaccharide found in the connective tissue space and the synovial fluid of movable joints and the humors of the eye; it protects tissue.
If you need to cite this page, you can copy this text:
Kenneth Barbalace. Chemistry & Environmental Dictionary - Half-life - Hyaluronic acid. EnvironmentalChemistry.com. 1995 - 2018. Accessed on-line: 7/19/2018 | <urn:uuid:e7624419-da3f-42dc-b28c-6146edb29ce9> | 3.265625 | 457 | Structured Data | Science & Tech. | 46.921922 | 95,616,795 |
While this CME was not Earth-directed, it has combined with an earlier CME, and the flank of the combined cloud may pass Earth. Particles from the CME cannot travel through the atmosphere to harm humans on Earth, but they can affect electronic systems in satellites and on the ground.
This image, captured at 11:06 a.m. EDT on May 22, 2013, from the ESA/NASA Solar and Heliospheric Observatory shows theconjunction of two coronal mass ejections streaming away from the sun. This image is what's known as a coronagraph, in which the light of the sun is blocked in order to make its dimmer atmosphere, the corona, visible. Credit: ESA and NASA/SOHO
Experimental NASA research models, based on observations from NASA’s Solar Terrestrial Relations Observatory and ESA/NASA’s Solar and Heliospheric Observatory show that the first CME began at 5:12 a.m. EDT, leaving the sun at about 400 miles per second. The second CME began at 9:24 a.m. EDT, leaving the sun at speeds of around 745 miles per second.
Earth-directed CMEs can cause a space weather phenomenon called a geomagnetic storm, which occurs when they funnel energy into Earth's magnetic envelope, the magnetosphere, for an extended period of time. In the past, geomagnetic storms caused by CMEs of this strength have usually been mild.
The NASA models also show that the combined CMEs will pass by the STEREO-A spacecraft and its mission operators have been notified. If warranted, operators can put spacecraft into safe mode to protect the instruments from the solar material.
NASA and NOAA – as well as the US Air Force Weather Agency (AFWA) and others -- keep a constant watch on the sun to monitor for space weather effects such as geomagnetic storms. With advance notification many satellites, spacecraft and technologies can be protected from the worst effects
NOAA's Space Weather Prediction Center (http://swpc.noaa.gov) is the U.S. government's official source for space weather forecasts, alerts, watches and warnings.
The sun emitted a mid-level solar flare on the morning of May 22, 2013. The flare peaked at 9:38 a.m. EDT and was classified as an M7. M-class flares are the weakest flares that can still cause some space weather effects near Earth. In the past, they have caused brief radio blackouts at the poles.
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. This disrupts the radio signals for as long as the flare is ongoing, anywhere from minutes to hours.
Increased numbers of flares are quite common at the moment, since the sun's normal 11-year activity cycle is ramping up toward solar maximum, which is expected in late 2013. Humans have tracked this solar cycle continuously since it was discovered in 1843, and it is normal for there to be many flares a day during the sun's peak activity.
NOAA's Space Weather Prediction Center (http://swpc.noaa.gov) is the U.S. government's official source for space weather forecasts, alerts, watches and warnings. Updates will be provided as they are available on the flare and whether there was an associated coronal mass ejection or CME, another solar phenomenon that can send solar particles into space and affect electronic systems in satellites and on Earth.Karen C. Fox
Karen C. Fox | EurekAlert!
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
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Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
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Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
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- Open Access
Microalgae as bioreactors for bioplastic production
© Hempel et al; licensee BioMed Central Ltd. 2011
Received: 29 June 2011
Accepted: 17 October 2011
Published: 17 October 2011
Poly-3-hydroxybutyrate (PHB) is a polyester with thermoplastic properties that is naturally occurring and produced by such bacteria as Ralstonia eutropha H16 and Bacillus megaterium. In contrast to currently utilized plastics and most synthetic polymers, PHB is biodegradable, and its production is not dependent on fossil resources making this bioplastic interesting for various industrial applications.
In this study, we report on introducing the bacterial PHB pathway of R. eutropha H16 into the diatom Phaeodactylum tricornutum, thereby demonstrating for the first time that PHB production is feasible in a microalgal system. Expression of the bacterial enzymes was sufficient to result in PHB levels of up to 10.6% of algal dry weight. The bioplastic accumulated in granule-like structures in the cytosol of the cells, as shown by light and electron microscopy.
Our studies demonstrate the great potential of microalgae like the diatom P. tricornutum to serve as solar-powered expression factories and reveal great advantages compared to plant based production systems.
About 140 million tons of plastic are consumed every year worldwide, which necessitates the processing of approximately 150 million tons of fossil fuels and directly causes immense amounts of waste that can take thousands of years to naturally deteriorate, if it degrades at all . Consequently, bioplastics are a feasible alternative in that they are not based on fossil resources and can easily be biodegraded. So far, however, production costs for petroleum-derived polymers still remain lower than biodegradable alternatives, which is a hindrance to commercial development and retail of environmentally friendly alternatives.
Poly-(R)-3-hydroxybutyrate (PHB) is an aliphatic polyester with thermoplastic properties, which is naturally produced by certain bacteria as storage compound and is 100% biodegradable [1–5]. PHB is synthesized from acetyl-CoA by the action of three enzymes: a ketothiolase, an acetoacetyl-CoA reductase and a PHB synthase . Under optimal conditions bacteria such as Ralstonia eutropha H16 can produce up to 80% PHB of cellular dry weight, and some companies have specialized on commercial PHB production (e.g. Metabolix Inc., Micromidas Inc.). Nevertheless, costs for PHB production by bacterial fermentation are still very high, which brought plants into focus as photosynthesis fueled low-cost production system [7–10]. The three bacterial enzymes were expressed in the cytosol or targeted to different compartments of the plant cell leading to high amounts of PHB accumulation in the plastids of Arabidopsis thaliana (up to 40% of dry weight) [11, 12]. However, due to stunted growth and infertility, these plants were not suitable for large-scale cultivation. Today, the highest levels of PHB synthesis in plants with fertile offspring are obtained in the plastid of Nicotiana tabacum resulting in up to 18% PHB of cellular dry weight .
In general, plant-based expression systems are very attractive in that no external organic carbon source is required, which is quite an important cost factor for large-scale production systems [14–16]. On the other hand, however, plant-based expression systems compete directly with subsistence crops for agricultural acreage and the dissemination of transgenic plants is difficult to control, which has been an ethical concern and led to strict regulatory controls of transgenic plants in many countries. Major drawbacks for the establishment of plant-based expression systems are the comparatively long growth rates resulting in a decrease in profitability. This casts a shadow on plant-based expression systems, rendering them unable to compete with the current well-established bacterial systems. Microalgae share all the advantages of photosynthetically driven eukaryotic systems but lack many of the mentioned disadvantages i.e. they possess high growth rates, are easy to handle and do not need much more than light and water for cultivation . Thus, microalgae are thought to have great potential as novel low-cost expression systems especially if aiming at the biosynthesis of recombinant proteins needed in numerous industrial, therapeutic or diagnostic applications [18–21].
In this study, we present for the first time a report on the biosynthesis of a biotechnologically relevant biopolymer in a microalgal system. We demonstrate that production of the bioplastic PHB is feasible in the diatom Phaeodactylum tricornutum by introducing the bacterial PHB pathway into the cytosolic compartment. PHB levels of up to 10.6% of algal dry weight were obtained revealing the great potential of this low-cost and environmentally friendly expression system.
Results and Discussion
The results of this study show for the very first time that PHB production is possible in a microalgae system. Interestingly, in comparison to efforts on PHB synthesis in the cytosol of plants, PHB expression levels in P. tricornutum are about 100-fold higher . This might be due to large lipid deposits present in the cytosol of P. tricornutum, as these microalgae naturally produce valuable omega-3-fatty acids [22–24]. Therefore, the acetyl-CoA pool, which is the basis for PHB synthesis, might be notably high in the cytosol of P. tricornutum and hence enable very efficient PHB production. To circumvent acetyl-CoA limitations as a drawback for PHB production in plants, other cellular compartments were tested, and indeed plastids, which provide a high acetyl-CoA content because of fatty acid synthesis, turned out to produce much higher levels of PHB [11, 12]. The best PHB synthesis levels in plants with fertile offspring thus far were achieved in tobacco with PHB contributing to 18% of dry weight . Upon a first glance, this looks promising, however, taking production time as an important economic factor into account plants do poorly in direct comparison to P. tricornutum, which needs approximately two weeks to accumulate similar PHB levels reached by plants during a vegetation period of 3 months.
Of course PHB production in P. tricornutum cannot presently compete with bioplastic production in R. eutropha, which was established commercially many years ago. Nevertheless, this pilot experiment together with many other current projects on microalgal biotechnology highlights the immense potential of these photosynthetically driven production systems. Surely, such progress in microalgal biotechnology will boost the development of efficient photobioreactors for use in large-scale cultivation, which is currently one of the most limiting factors to put low-cost production into practice.
Altogether, this study has demonstrated that microalgae like the diatom P. tricornutum have a great potential not only as biosynthetic factory for recombinant proteins but also as photosynthetically fueled bioreactors for synthesizing biotechnologically relevant polymers like PHB. Even though no enzyme engineering, no adaptations to P. tricornutum specific codon-usage, and no large-scale screening have been applied in these initial analyses, relatively high PHB levels of up to 10.6% of algal dry weight have been obtained. Thus, in the future, there will be a focus on various targets for enhancing PHB biosynthesis in P. tricornutum. Other subcellular compartments such as the plastids might yet be interesting sites for PHB synthesis. Diatoms are naturally rich in lipids and silicate and already have applications in biotechnology . Hence, inserting and/or altering biochemical pathways in diatoms in order to synthesize complex molecules, biologically active substances, and raw materials may have a number of applications in for example the nanotechnology industry and the production of renewable biofuels.
Plasmid construction and P. tricornutum transfection
Plasmid pBHR68 was used as template for amplification of phaA, phaB and phaC genes from R. eutropha H16. For in vivo localization studies sequences were cloned upstream to the eGFP (enhanced green fluorescent protein) sequence into the vector pPha-NR, which is a derivative of pPhaT1 with endogenous nitrate reductase promoter/terminator flanking the multiple cloning site [GenBank:JN180663]. The inducible nitrate reductase promoter system was established earlier in the diatom C. fusiformis by Poulsen et al. 2005 . Transfection proceeded as described previously with the exception that cells were grown under non-induced conditions with NH4+ as sole nitrogen source. For PHB synthesis in P. tricornutum, the sequence for phaC was cloned into the vector pPha-NR (not containing eGFP), and sequences of phaA and phaB were inserted into the vector pPha-DUAL[2xNR], which is a pPha-NR derivative with two multiple cloning sites both under the control of endogenous nitrate reductase promoter [GenBank:JN180664]. Both plasmids were mixed and co-transfected under non-induced conditions.
Cell culture and induction of recombinant protein expression
Cells were grown in f/2 medium under standard conditions as described elsewhere (Apt et al. 1999) with either 0.9 mM NO3- or 1.5 mM NH4+ as the nitrogen source. For in vivo localization studies on GFP fusion proteins transfectants were grown in media containing NO3- to induce recombinant protein expression. After 3 days, clones were analyzed by confocal laser scanning microscopy. PhaA/phaB/phaC co-transfectants were first determined to have genomic integration by colony PCR for all three sequences. Subsequently, positive colonies were grown in liquid culture containing NH4+ and allowed to reach exponential phase, whereupon they were transferred to NO3- containing medium for varying time periods. For visualization of PHB granules, cells were induced for 5 days and analyzed by electron and confocal microscopic analyses, respectively. For confocal microscopy, cells were pre-incubated with the lipophilic dye Nile Red (0.5 μg/ml) for 24 h.
For analyses on PHB production cultures were grown in NH4+ containing medium, washed in nitrogen-free medium and transferred to NO3- containing medium for 7 days. Cells were harvested (1500 × g, 10 min), washed with phosphate buffered saline (PBS) and lyophilized for 24 hours. The PHB contents of the cells were determined upon methanolysis of 5 to 10 mg lyophilized cells in presence of 2 ml methanol/sulfuric acid (85:15, v/v) and 2 ml chloroform. The resulting methyl esters of 3-hydroxybutyrate were analysed by gas chromatography using an Agilent 6850 GC (Agilent Technologies, Waldbronn, Germany) as described previously [28, 29].
Fluorescence and electron microscopy
In vivo localization of GFP fusion proteins was analysed with a confocal laser scanning microscope Leica TCS SP2 using a HCX PLAPO 63x/1.32-0.6 oil Ph3 CS objective. GFP, chlorophyll and Nile Red were excited at 488 nm, and fluorescence was detected at a bandwidth of 500-520 nm, 680-720 nm and 580-600 nm, respectively. For electron microscopic analyses, cells were centrifuged at 2000 × g for 5 min followed by cryo-fixation and resin embedding. The samples were high-pressure frozen in a Leica EM-PACT 2 and subsequently freeze substituted (Leica EM AFS 2; Leica, Vienna, Austria) with pure acetone containing 2% (w/v) osmium tetroxide, 0.1% (w/v) uranyl acetate and 5% (v/v) H2O. Freeze substitution was carried out at -90°C for 4 h, -60°C for 8 h, -30°C for 8 h and held at 0°C for 3 h with a heating time of 1 h in between each step. After washing the samples with ice cold acetone for three times and infiltration in Epon 812 (Ted Pella, Inc., USA) for 24 h, the resin was polymerized at 60°C for 72 h. Ultrathin sections were cut with a Leica Ultracut (Leica, Vienna, Austria), mounted on uncoated 400 mesh copper grids and post-stained with 2% (w/v) uranyl acetate for 20 min and 0.5% (w/v) lead citrate for 1 min. Transmission electron microscopy was carried out on a JEOL 2100 TEM operated at 80 kV in combination with a fast-scan 2 k × 2 k CCD camera F214 (TVIPS, Gauting, Germany).
We are grateful to Jan Bamberger from Marburg for his technical assistance in initial gas chromatographic analyses on PHB accumulation. Prof. Reinhard Rachel and Prof. Ralph Witzgall from Regensburg we thank for providing high pressure freezing and freeze substitution facilities. Furthermore, we thank Marion Debus for technical assistance with electron microscopic preparations. This work was supported by the LOEWE program of the state of Hessen (Germany).
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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. | <urn:uuid:029412c8-da3e-43e5-96a9-fdb9645134f5> | 2.671875 | 5,159 | Truncated | Science & Tech. | 54.830955 | 95,616,868 |
Created by Microsoft with.NET, WCF (Windows Communication Foundation), provides platforms to build secure and reliable service. While Web API framework is used to make HTTP service and is used to create complete REST service.
In this article, we will discuss the basic differences between Web API and WCF:
Representational State Transfer (REST)
Rest is the architecture design pattern, used to build and create Web Services. These architecture design patterns are used by the Web API to build web services. Web API utilizes POST, DEL, PUT and GET verbs for the communication purposes to the client and is fully REST supported.
Simple Object Access Protocol [SOAP]
Invented by Microsoft, SOAP is a protocol, which creates an organized format information or message, which can be transferred to the internet. It uses XML format and is the main foundation of WCF. While, WSDL is the file created by Web Service, and it is basically utilized by the client to find out the methods that are available on the service.
HTTP response/requests are normally smaller as compared to SOP response/request, because, RESTful services use HTTP protocol to get access to the client. So, Web API is the best option to access client, especially for low bandwidth devices/mobile devices.
When we compare WCF vs Web API, both of these frameworks provide security standards, Web API utilizes web standard security, for example, fundamental validation, token verification and for more intricate, for example, OAuth; Web API gives greater adaptability. At that point utilize SOAP when you will validate with outside administrations, for example, google, facebook, and so forth.
But, WCF service gives us high-level security system which gives enterprise-level security. It utilizes WS-I standard to give secure service.
Along these lines, we can’t choose which is superior to the next. Be that as it may, I would focus on the two points. Initially, WCF is best if you want to create service on various platform and Web API is best if you are going to create internet service for different platforms.
- Deependra is a Senior Developer with Microsoft technologies, currently working with Opteamix India business private solution. In My Free time, I write blogs and make technical youtube videos. Having the good understanding of Service-oriented architect, Designing microservices using domain driven design. | <urn:uuid:56c46e46-5b1c-4c50-93de-bb1a29b777f9> | 2.9375 | 493 | Personal Blog | Software Dev. | 34.05625 | 95,616,887 |
Eruption of enormous flare from exploded supernova baffles Nasa scientists
- Flare five times more powerful than those previously seen
An enormous flare which erupted from the remnants of an exploded star in a faraway constellation has left Nasa scientists baffled.
Last month, the famous Crab Nebula supernova, first observed in 1731, gave off a flare five times more powerful than any previously seen from the object.
On April 12, Nasa's Fermi Gamma-ray Space Telescope first detected the outburst, which lasted six days.
Scroll down for video
The Crab Nebula, the wreckage of an exploded star, last month gave off a flare five times more powerful than any previously seen from the object
On April 12, a flare was detected that grew about 30 times more energetic than the Crab Nebula's normal gamma-ray output
The nebula is the wreckage of an exploded star that emitted light which reached Earth in the year 1054.
It is located 6,500 light-years away in the constellation Taurus. At the heart of an expanding gas cloud lies what is left of the original star's core, a superdense neutron star that spins 30 times a second.
With each rotation, the star swings intense beams of radiation toward Earth, creating the pulsed emission characteristic of spinning neutron stars, known as pulsars.
Apart from these pulses, astrophysicists believed the Crab Nebula was a virtually constant source of high-energy radiation.
But in January, scientists associated with several orbiting observatories, including NASA's Fermi, Swift and Rossi X-ray Timing Explorer, reported long-term brightness changes at X-ray energies.
'The Crab Nebula hosts high-energy variability that we're only now fully appreciating,' said Rolf Buehler, a member of the Fermi Large Area Telescope (LAT) team at the Kavli Institute for Particle Astrophysics and Cosmology, a facility jointly located at the Department of Energy's SLAC National Accelerator Laboratory and Stanford University.
Since 2009, Fermi and the Italian Space Agency's AGILE satellite have detected several short-lived gamma-ray flares at energies greater than 100 million electron volts (eV) -- hundreds of times higher than the nebula's observed X-ray variations. For comparison, visible light has energies between 2 and 3 eV.
On April 12, Fermi's LAT, and later AGILE, detected a flare that grew about 30 times more energetic than the nebula's normal gamma-ray output and about five times more powerful than previous outbursts.
The Crab Nebula (inset) against a full-sky gamma ray map (the location of the nebula is marked by cross-hairs). Since 2009, several short-lived gamma-ray flares at energies greater than 100 million electron volts have been detected
On April 16, an even brighter flare erupted, but within a couple of days, the unusual activity completely faded out.
'These superflares are the most intense outbursts we've seen to date, and they are all extremely puzzling events,' said Alice Harding at NASA's Goddard Space Flight Center in Greenbelt, Md. 'We think they are caused by sudden rearrangements of the magnetic field not far from the neutron star, but exactly where that's happening remains a mystery.'
The Crab's high-energy emissions are thought to be the result of physical processes that tap into the neutron star's rapid spin. Theorists generally agree the flares must arise within about one-third of a light-year from the neutron star, but efforts to locate them more precisely have proven unsuccessful so far.
Since September 2010, NASA's Chandra X-ray Observatory routinely has monitored the nebula in an effort to identify X-ray emission associated with the outbursts. When Fermi scientists alerted astronomers to the onset of a new flare, Martin Weisskopf and Allyn Tennant at NASA's Marshall Space Flight Center in Huntsville, Ala., triggered a set of pre-planned observations using Chandra.
'Thanks to the Fermi alert, we were fortunate that our planned observations actually occurred when the flares were brightest in gamma rays,' Weisskopf said. 'Despite Chandra's excellent resolution, we detected no obvious changes in the X-ray structures in the nebula and surrounding the pulsar that could be clearly associated with the flare.'
Scientists think the flares occur as the intense magnetic field near the pulsar undergoes sudden restructuring. Such changes can accelerate particles like electrons to velocities near the speed of light. As these high-speed electrons interact with the magnetic field, they emit gamma rays.
To account for the observed emission, scientists say the electrons must have energies 100 times greater than can be achieved in any particle accelerator on Earth.
This makes them the highest-energy electrons known to be associated with any galactic source.
Based on the rise and fall of gamma rays during the April outbursts, scientists estimate that the size of the emitting region must be comparable in size to the solar system.
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In 1913, Stark observed a splitting of the lines of the Balmer series of hydrogen (8.2) in an electric field. He was studying the light emission of H atoms in the field of a condenser (Figs. 15.1, 2). Since then, frequency shifts in optical spectra in the presence of eletric fields have been generally called the Stark effect.
KeywordsRadiation Field Electric Field Strength Occupation Number Schrodinger Equation Principal Quantum Number
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- N. F. Ryde: Atoms and Molecules in Electric Fields (Almqvist and Wicksell, Stockholm 1976)Google Scholar | <urn:uuid:9795e597-8f04-4383-b68e-0676f20eaa92> | 2.84375 | 140 | Academic Writing | Science & Tech. | 61.8325 | 95,616,911 |
Despite the absence of a global Earth-like magnetic dipole, the Martian atmosphere is well protected from the effects of the solar wind on ion escape from the planet. New research shows this using measurements from the Swedish particle instrument ASPERA-3 on the Mars Express spacecraft. The results have recently been presented in a doctoral thesis by Robin Ramstad, Swedish Institute of Space Physics and Umeå University, Sweden.
Present-day Mars is a cold and dry planet with less than 1% of Earth’s atmospheric pressure at the surface. However many geological features indicate the planet had an active hydrological cycle about 3-4 billion years ago. An active hydrological cycle would have required a warmer climate in the planet’s early history and therefore a thicker atmosphere, one capable of creating a strong greenhouse effect.
Left: Charged particles from the sun (the solar wind) form an induced magnetosphere round Mars, which unlike the sun does not have its own intrinsic magnetic field (artwork: Anastasia Grigoryeva).
Right: Robin Ramstad points out the position of the Swedish instrument ASPERA-3 on a model of the Mars Express spacecraft (photo: Anastasia Grigoryeva)
A common hypothesis maintains that the solar wind over time has eroded the early Martian atmosphere, causing the greenhouse effect, and thus the hydrological cycle, to collapse. Unlike Earth, Mars has no global magnetic dipole, but the solar wind instead induces currents in the ionized upper atmosphere (the ionosphere), creating an induced magnetosphere.
“It has long been thought that this induced magnetosphere is insufficient to protect the Martian atmosphere,” says Robin Ramstad. “However our measurements show something different.”
The Swedish-led ion mass analyser on Mars Express has been measuring the ion escape from Mars since 2004. In his research, Robin Ramstad has combined and compared measurements of the ion escape under varying solar wind conditions and levels of ionizing solar radiation, so-called extreme ultraviolet (EUV) radiation.
The results show that the solar wind has a comparatively small effect on the ion escape rate, which instead mainly depends on the EUV radiation. This has a large effect on estimations of the total amount of atmosphere that has escaped to space.
“Despite stronger solar wind and EUV-radiation levels under the early Sun, ion escape can not explain more than 0.006 bar of atmospheric pressure lost over the course of 3.9 billion years,” says Robin Ramstad. “Even our upper estimate, 0.01 bar, is an insignificant amount in comparison to the atmosphere required to maintain a sufficiently strong greenhouse effect, about 1 bar or more according to climate models.”
The results presented in the thesis show that a stronger solar wind mainly accelerates particles already escaping the planet’s gravity, but does not increase the ion escape rate. Contrary to previous assumptions, the induced magnetosphere is also shown to protect the bulk of the Martian ionosphere from solar wind energy transfer.
Robin Ramstad is from from Västerås in Sweden and has a Master of Science degree in Engineering Physics from Luleå University of Technology.
On Friday 8 December 2017 Robin Ramstad of the Swedish Institute of Space Physics in Kiruna and Umeå University will defend his PhD thesis entitled Ion escape from Mars: measurements in the present to understand the past.
The thesis defence will take place at 9 am in the Aula at the Swedish Institute of Space Physics in Kiruna.
The faculty opponent is Assoc. Prof. David Brain, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, USA. The candidate’s supervisors are Prof. Stas Barabash and Assoc. Prof. Yoshifumi Futaana at the Swedish Institute of Space Physics, Kiruna.
Robin Ramstad, Swedish Institute of Space Physics, email@example.com, tel. +46-980-79115
Rick McGregor, Information Officer, Swedish Institute of Space Physics, firstname.lastname@example.org, tel. +46-980-79178
Information about the defence and a link to the thesis: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-141892
IRF’s Mars Express web page: http://www.irf.se/link/MEX_press
AGU Editor’s Highlight of Robin Ramstad’s GRL paper: https://eos.org/editor-highlights/where-did-the-water-go-on-mars
Rick McGregor | 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....
13.07.2018 | Event News
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20.07.2018 | Power and Electrical Engineering
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Jun 15, 2010
Mathaeus Sea Urchin (Echinometra mathaei)
Depth: 0 to –8 m.
Distribution : Red Sea to Polynesia
Environment : reef roofs, protected reef slopes
Climate : warm waters
Mathaeus Sea Urchin is a frequent inhabitant of the reef. He is to be found on the reef roof and at the upper reef slopes. During the day they hide themselves in holes (scraped by their own) in the coral rocks, before they come out at night to food search. The contrast between the reddish-brown pricks and the white basal ring is salient.
Model 1 specs: 10 centimeters
Model 2 specs: 5 centimeters
Model 3 specs: 10 centimeters | <urn:uuid:a414ce86-18d0-4818-b348-0c9825092541> | 2.828125 | 151 | Knowledge Article | Science & Tech. | 63.205679 | 95,616,926 |
The problem states:
You have two flat metal plates, each of area 1.00 m^2, with which to construct a parallel-plate capacitor.
(a) If the capacitor of the device is to be 1.00 F, what must be the separation between the plates?
(b) Could this capacitor actually be constructed?
Please review my solution below and correct me where I am may be wrong, explaining any concepts I may be misunderstanding.
(a) The formula to calculate Capacitance is
C = ε0A / d
C = 1.00 F
ε0 = 8.85 pF/m
A = 1.00 m^2
d = ε0A / C
d = (8.85 μF/m)(1.00 m^2) / 1.00 F
d = 8.9 μm or 8.9 x 10^-12 m
(b) This is a very small distance and we know the smaller the distance the larger the capacitance. A 1 F capacitor is extremely large and probably would not be cost effective for the size to the materials needed.© BrainMass Inc. brainmass.com July 22, 2018, 10:26 pm ad1c9bdddf
The solution calculates capacitance. | <urn:uuid:b56c30a5-2d10-4479-82ef-44998a2d79d9> | 3.484375 | 270 | Q&A Forum | Science & Tech. | 94.616762 | 95,616,932 |
Seismic inversion can be classified as
- Methods based on iterative forward modeling
- Methods based on downward wave field extrapolation
Inversion by iterative forward modeling:
- Essentially in this method, elastic properties of the geological subsurface are estimated.
- Given the seismic source and an initial subsurface model, a seismic data is simulated. The simulated data is then compared to the actual measured data and using the residual, the subsurface model is refined iteratively until the residual reaches a minimum.
Benefit: Really accurate
Drawback: Computationally very expensive
Inversion by downward wave field extrapolation:
- It is the most commonly used method in the industry (migration). Here, the seismic waves (measured reflection data and the assumed/measured source) are downward extrapolated at every depth point. Thereafter, at every depth location a reflectivity is derived using an imaging condition.
- In this method, reflectivity of the geological boundaries is estimated by extrapolating the source and reflected wave fields into the subsurface using pre-specified velocity model.
- In the standard practice of migration, forward modelling of reflections is not done, neither is a residual calculated.
Benefit: Efficient compared to previous method
Drawback: The theoretical foundation is not reliable | <urn:uuid:bf024d47-2b29-49f3-9675-ab5a9780323f> | 3.109375 | 270 | Tutorial | Science & Tech. | -3.39125 | 95,616,949 |
Scientists Reveal Different Dynamics of Droplet Formation on Fibers.
Thin fibers play a tremendous role in daily life, from the use of glass fibers in ultra-fast data transmission to textile fibers. In order to enable special properties of these fibers, they are often coated with a thin liquid layer that is supposed to be stable and homogeneous.
However, for the production of drinkable water, the exact opposite features are desired: there, one aims at harvesting water, which is transported along the fiber as a liquid film or as liquid droplets, from fog. Now, scientists have been able to reveal whether liquid films slowly flow along the fiber or if they can slip faster on the fiber.
The team composed of Karin Jacobs and Sabrina Haefner from Saarland University, together with Oliver Bäumchen from the Max Planck Institute for Dynamics and Self-Organization in Göttingen, and colleagues from Canada and France have been able to show for the first time, by means of novel experiments and mathematical models, how a liquid film moves on a fiber, depending on the fiber coating. The results of this study have now been published in the high-ranked journal “Nature Communications”.
Many examples for liquids on fibers are known in nature. Just think about dew droplets on spider webs that you can observe during a walk in the morning. Indeed, humidity is collected on the fiber as droplets, as the liquid surface can be minimized this way. This phenomenon, which can also be observed for a stream of water flowing out of a faucet, is named the Rayleigh-Plateau instability.
“All systems drive towards their energetic minimum, and that is the droplet shape in this case”, says Sabrina Haefner, a physicist in the research group of Karin Jacobs. This instability can be very useful in very dry and remote regions of the world. For example, in Chile’s Atacama desert, the acquisition of drinkable water is essential for the locals and they harvest water from the humidity by means of fiber nets.
In industrial applications, however, it is often necessary to realize stable and homogeneous liquid films on fibers. So how does one manage to avoid this droplet formation? “The surface energy of the liquid, its viscosity, the thickness of the liquid film, as well as the diameter of the fiber, play an important role”, explains Karin Jacobs. The international team of researchers has now found that the properties of the fiber itself also have a strong impact. “The contact between the liquid and the fiber is indeed very important”, says Oliver Bäumchen from the Max Planck Institute for Dynamics and Self-Organization.
“If the liquid slips on the fiber surface, the droplet formation is much faster than in the case of just flow along the fiber”. The team of physicists tested this for liquid films supported by uncoated and Teflon-coated fibers. On uncoated fibers, the liquid film moved rather slowly, and droplet formation took longer, than on coated fibers, where the liquid film was able to slip. “In line with mathematical models, these experiments allow for quantifying ’slippage’ of liquid films and to precisely predict the dynamics of the droplet formation process”, says Sabrina Haefner from Saarland University. The team of researchers agrees: Their results are very important for the design of novel fiber coatings.
The international team of researchers is composed of experimental and theoretical physicists from Saarland University (Saarbrücken, Germany), the Max Planck Institute for Dynamics and Self-Organization (Göttingen, Germany), McMaster University (Hamilton, Canada) and the ESPCI (Paris, France).
The study by S. Haefner, M. Benzaquen, O. Bäumchen, T. Salez, R. Peters, J.D. McGraw, K. Jacobs, E. Raphaél, and K. Dalnoki-Veress with the title “Influence of Slip on the Plateau-Rayleigh Instability on a Fibre“ has been published in the high-ranked journal “Nature Communications”:
A picture from the study can be downloaded here: http://www.uni-saarland.de/pressefotos
A video from the study can be found here: https://www.youtube.com/watch?v=jxEUfXvQ_Ms
Prof. Dr. Karin Jacobs
Saarland University, Experimental Physics
Tel.: 0049 - 681 302-71788
Dr. Oliver Bäumchen
Max Planck Institute for Dynamics and Self-Organization Göttingen
Tel.: 0049 - 551 5176-260
Gerhild Sieber | Universität des Saarlandes
First evidence on the source of extragalactic particles
13.07.2018 | Technische Universität München
Simpler interferometer can fine tune even the quickest pulses of light
12.07.2018 | University of Rochester
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Specifically, the Paris-Harrington theorem.
In what sense is it true? True in Peano arithmetic but not provable in Peano arithmetic, or true in some other sense?
Peano Arithmetic is a particular proof system for reasoning about the natural numbers. As such it does not make sense to speak about something being “true in PA” — there is only “provable in PA”, “disprovable in PA”, and “independent of PA”.
When we speak of “truth” it must be with respect to some particular model. In the case of arithmetic statements, the model we always speak about unless something else is explicitly specified is the actual (Platonic) natural numbers. Virtually all mathematicians expect these numbers to “exist” (in whichever philosophical sense you prefer mathematical objects to exist in) independently of any formal system for reasoning about them, and the great majority expect all statements about them to have objective (but not necessarily knowable) truth values.
We’re very sure that everything that is “provable in PA” is also “true about the natural numbers”, but the converse does not hold: There exist sentences that are “true about the actual natural numbers” but not “provable in PA”. This was famously proved by Gödel — actually he gave a (formalizable, with a few additional technical assumptions) proof that a particular sentence was neither “provable in PA” nor “disprovable in PA”, and a convincing (but not strictly formalizable) argument that this sentence is true about the actual natural numbers.
Paris-Harrington shows that another particular sentence is of this kind: not provable in PA, yet true about the actual natural numbers.
The Paris-Harrington theorem is actually the theorem that states that the strengthened [finite] Ramsey theorem is unprovable in first-order Peano Arithmetic.
However, since the Ramsey theorem is provable in second-order arithmetic, and therefore true in the standard model of Peano arithmetic, we can say that the theorem is true in a very deep and concrete sense.
Generally speaking, when we say a statement about the integer is true we mean that it is true in the standard model, which is the model of second-order Peano arithmetic, and it is all the numbers which can be generated by finitely many iteration of the successor function from zero. (Non-standard models of first-order PA exist, and there are non-standard integers which cannot be generated by finite iterations of the successor from zero.)
You may also want to read this thread about the difference between truth and provability.
The other answers are excellent, but I would like to point out that Peano arithmetic is a particularly bad first example for understanding the distinction between truth and provability because
So let’s pick a better example where there’s no possibility of confusion: the first-order theory of groups. I’m not going to spell out in detail what this is; consider it an exercise to write it down in full. After writing down the language of groups, write down the group theory axioms.
“Provable” has an unambiguous meaning here: it means “provable from the axioms of group theory.” By the completeness theorem, this is equivalent to “true for all groups.”
“True” is meaningless here unless you take it to mean “true for all groups,” which is not the sense in which the Paris-Harrington theorem is true. What is meaningful is to say that a statement in the language of groups is true in a particular model: for example, the statement
$$\exists g : g \neq e, g^2 = e$$
is true in a group $G$ precisely when that group has a nontrivial element of order $2$.
The difference between group theory and first-order Peano arithmetic is that when it comes to Peano arithmetic, mathematicians have a special model that they really like, namely the “actual natural numbers,” and “true” in this context means “true of this special model.” As Asaf says, one way to define this model is as the unique model of second-order Peano arithmetic; however, first-order Peano arithmetic does not have a unique model (e.g. by upward Löwenheim-Skolem).
This is very different from the situation with group theory; nobody has a group $G$ that they like so much that they would define “true” to mean “true of $G$”!
As a final remark, note that by the completeness theorem, “true of the actual natural numbers but not provable” is equivalent to “true of the actual natural numbers but false for some other model of Peano arithmetic.” This may seem like a strange state of affairs, but the analogous situation in group theory (“true of some group but false of some other group”) is not so strange.
You seem to be confused about the meaning of true when it comes to peano arithmetic. Peano arithmetic usually refers to a particular set of axions about the natural numbers, formalized in first-order predicate logic.
If you have a statement $A$ and a set of axioms $T$ it can be that
In the case of PA, people might also say “True over the integers” or simply “true” instead of “True over the standard model of PA”. Especially because PA is not the only axiomatization of the integers.
The generalized Ramsey theorem (sometimes called Paris-Harrington Principle, btw) is not provable in PA, but it is true in the stanard model of PA, i.e. in the usual integers. We know that because it is provable in second-order arithmetic, i.e. a second-order axiomatization of the integers.
Note that (according to Wikipedia) the proof of the Paris-Harrington theorem goes by assuming it is true in Peano arithmetic and showing this can prove Peano is consistent (within Peano).
Because Gödel has shown this is not possible, it must not be possible to prove the theorem in Peano.
So as far as understanding it, you can fall back on Gödel: he showed there are statements in a formal theory that cannot be proved (or disproved) by that theory but are true in a formal theory with more axioms. This is one of those statements for Peano. | <urn:uuid:69321a72-6bb0-4096-bc8b-7f20cc4aef70> | 2.875 | 1,410 | Comment Section | Science & Tech. | 40.809367 | 95,616,961 |
In comparison to classical physics, quantum physics predicts that the properties of a quantum mechanical system depend on the measurement context, i.e. whether or not other system measurements are carried out.
A team of physicists from Innsbruck, Austria, led by Christian Roos and Rainer Blatt, have for the first time proven in a comprehensive experiment that it is not possible to explain quantum phenomena in non-contextual terms. The scientists report on their findings in the current issue of Nature.
Quantum mechanics describes the physical state of light and matter and formulates concepts that totally contradict the classical conception we have of nature. Thus, physicists have tried to explain non-causal phenomena in quantum mechanics by classical models of hidden variables, thereby excluding randomness, which is omnipresent in quantum theory. In 1967, however, the physicists Simon Kochen and Ernst Specker proved that measurements have to be contextual when explaining quantum phenomena by hidden variables. This means that the result of one measurement depends on which other measurements are performed simultaneously. Interestingly, the simultaneous measurements here are compatible and do not disturb each other.
Randomness cannot be excluded
In 1935 already, Albert Einstein, Boris Podolsky and Nathan Rosen questioned whether quantum mechanics theory is complete in the sense of a realistic physical theory – a criticism that is now well know in the scientific world as the EPR paradox. In the mid 1960s, John Bell showed that quantum theory cannot be a real and at the same time local theory, which, in the meantime, has also been proven experimentally. Kochen and Specker's results exclude other theoretical models but until now it was difficult to provide a convincing experimental proof. Following a proposition by the Spaniard Adán Cabello, the Innsbruck scientists have now successfully proven this point and produced unambiguous results experimentally. The physicists are supported by the Austrian Science Funds (FWF), the European Union, the Federation of Austrian Industry Tyrol, and Intelligence Advanced Research Projects Activity (IARPA).
Christian Roos | EurekAlert!
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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The rate at which science is developing before our eyes is sometimes almost frightening. Things that once were deemed impossible are now on the verge of being so, and human life looks set to become ever easier, more exciting and exponentially more interesting with every new scientific discovery.
There's a lot of barely-founded 'scientific' knowledge floating around these days, but one of the best resources for scientific facts that seem to be backed up by reliable research is the popular 'I F**king Love Science', which started as Facebook group (and now has its own official site) set up by a British student named Elise Andrew. Andrew set up her Facebook page which reveals crazy facts about the physical world in 2012. Andrew states that she just wanted a place to post up any information relating to her nerdy love of all things scientific, and began posting material under several major categories, including Biology, Chemistry, Physics, Space and The Brain.
Andrew certainly didn't expect the impact that her page would have. Currently, IFLS has almost 16 million likes. It is undeniable that Andrew has had a huge impact, bringing scientific thought to the news feeds of today's teens. Here, we've compiled some of the most stunning facts that have been shared on Andrew's site in recent months. Although all of these discoveries and facts differ enormously, all of them show just how fascinatingly brilliant the human race is. Take a look at these 9 almost unbelievable facts to have your mind blown by the wonder of science. As Neil deGrasse Tyson once famously stated: "The good thing about science is that it's true whether or not you believe in it.”
9 Tears Change Shapes Depending On Your Emotions
Rose-Lynn Fisher is a photographer whose 2010 photography project was focused on the science of tears. Using a microscope, Fisher examined different types of tears and their forms. "Different types of tears" means the differing reasons why the tears were shed. Some of the categories that were examined were tears of grief, tears of joy, tears of laughter and onion tears. When the dried tears were compared under a microscope, the results were mesmerising, as well as incredibly varied. It appears that different kinds of tears have different shapes. It must be noted that, as Fisher admits herself, although the test was scientifically accurate, the way in which the tears dry is a huge variable.
8 Playing Video Games DOES Makes Your Smarter
It has been heavily debated for a number of years, but finally, it seems that there is conclusive proof that playing video games can actually make you smarter. In fact, video games seem to cause a significant increase in grey matter in the player's brain. Playing improves various skills such as memory, hand-eye coordination and strategic thinking. An in-depth study on the impact video games have on the brain was carried out by Simone Kühn. The experiment monitored brains before and after playing (Super Mario was the game of choice) via MRI scan.
7 Flies Think Before They Act
As weird as this sounds, its actually true. Common fruit flies have recently been studied by psychologists and it has been found that they actively deliberate before making a decision. Researchers at Oxford studied the fruit flies by placing them in a situation in which they would have to make a decision. The flies were placed in chambers that had a unique scent pumped into them. The flies were trained to leave the chamber when the scent became very powerful. The scientists then compared this reaction to their reaction when small amounts of the scent were added to the chamber. The flies hesitated before flying away. What the scientists deduced from this is that the flies were trying to discern whether or not the scent was strong enough that they should leave. Incredible!
6 Regrowing Teeth Is Now Possible
At Harvard’s Wyss Institute, scientists have already succeeded in re-growing rat teeth from stem cells. Their plan now is to launch the possibility for humans, which would revolutionise dentistry forever. If this discovery is eventually used in mainstream dentistry practises, then cavities and root canals would essentially become things of the past. Using lasers, the scientists have discovered a way to make stem cells grow into new teeth. What's even better is that the same technology could also be used in the future to grow new bones from stem cells.
5 The Pentagon Is Preparing For a Zombie Apocalypse
According to Foreign Policy Magazine, the Pentagon has created documents that outline a plan of what to do in case of a zombie apocalypse. Believe it or not, this is actually true. The detailed files imagine all of the possible zombie apocalypse scenarios and offer advice as to how these hypothetical situations could be dealt with. Some of the types of zombies mentioned include chicken zombies and "evil magic" zombies. Upon the revelation of the documents, the Pentagon has faced the scorn of many. However, the documents fight their corner by claiming that they are simply preparing for every eventuality.
4 Humans Have Littered Every Crevice of the Planet - Literally
Recently, a survey was done in which a submarine examined the ocean's depths off the coasts of Europe. Various kinds of trash were found almost 5 kilometres below the surface. The survey provides a rather depressing insight into how serious the problem of pollution has become. For this particular survey, the area examined was an area that had never been reached by humans before - yet, humans' pollution has managed to touch these parts. One of the women involved with the study stated "Most of the deep sea remains unexplored by humans, and these are our first visits to many of these sites, but we were shocked to find that our rubbish has got there before us."
3 Solar Roads Could Power Cars In The Future
Scott and Julie Brusaw's innovative project "Solar Roadways" looks set to change many lives in the future. The project is centred around solar powered roads. These solar powered roads could offer a myriad of benefits. First of all, they could be a solution to the need for fossil fuels to power cars. Instead of using gas, electric cars could be powered by their own friction on the road. The benefits don't stop there - as the solar panels would always be heated, ice and snow would not be able to remain on roads for long periods of time, cutting the risk of road accidents. The panels have solar powered lights too, meaning that the roads light your way at night without the need for electric street lamps.
2 Ancient Artefacts Might Be Stored On The Moon
When you think about it, it really is the perfect place. Apparently, there are plans in place to relocate the Sefer Torah, an ancient jewish text, to the moon. This could well be the case for other precious artefacts in the future. The idea behind this mass relocation of cultural treasures is that the world simply isn't a safe place anymore. Many historians believe that man's historical treasures should not be victims of our frivolous approach to the earth. However, there are many things that need to be tested before such a project could begin. First of all, a method for preserving and protecting the artefacts on the moon needs to be finalised. It is certain that the artefacts will need to be contained in protective cases, otherwise they would be destroyed by heat and radiation. The flags that Neil Armstrong left on the moon during the first moon landing are now completely colourless, damaged by harsh conditions.
1 The Formation of Memories Was Captured On Film
For hundreds of years, the concept of memory has puzzled human beings. Even today, advanced neuroscientists still struggle to comprehend the vast complexity of memory. Memory is something that plays a huge role in everyone's lives, yet it is still shrouded in mystery. Recently, however, some stunning footage was captured on film in the Albert Einstein College of Medicine. Using extremely high-tech equipment, the proteins that make up memories were filmed forming and moving in the neurons of a mouse's brain.
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Literally years in the making, the new radiometer, which is designed to measure the intensity of electromagnetic radiation, specifically microwaves, is equipped with one of the most sophisticated signal-processing systems ever developed for an Earth science satellite mission.
This photograph shows the SMAP propellant tank after installation at NASA's Jet Propulsion Laboratory in Pasadena, Calif. The propulsion tank was made by ATK Space Systems in Commerce, Calif. The technicians and engineers pictured are (left to right) John Shuping, Ryan Van Schilfgaarde, Bob Path and Vinh Dang. Credit: NASA JPL/Corinne Gatto Credit: NASA
Its developers at NASA’s Goddard Space Flight Center in Greenbelt, Md., shipped the instrument to NASA’s Jet Propulsion Laboratory in Pasadena, Calif., where technicians will integrate it into the agency’s Soil Moisture Active Passive spacecraft, along with a synthetic aperture radar system developed by JPL.
With the two instruments, the NASA mission will globally map soil moisture levels — data that will benefit climate models — when it begins operations a few months after its launch in late 2014. In particular, the data will give scientists the ability to discern global soil moisture levels, a crucial gauge for drought monitoring and prediction, and fill gaps in scientists’ understanding of the water cycle. Also important, it could help crack an unsolved climate mystery: the location of the places in the Earth system that store carbon dioxide.
Years in the Making
Building the new radiometer took years to accomplish and involved the development of advanced algorithms and an onboard computing system capable of crunching a deluge of data estimated at 192 million samples per second. Despite the challenges, team members believe they’ve created a state-of-the-art instrument that is expected to triumph over the data-acquisition troubles encountered by many other Earth-observing instruments.
The signal received by the instrument will have penetrated most non-forest vegetation and other barriers to gather the naturally emitted microwave signal that indicates the presence of moisture. The wetter the soil, the colder it will look in the data.
The instrument’s measurements include special features that allow scientists to identify and remove the unwanted “noise” caused by radio-frequency interference from the many Earth-based services that operate near the instrument’s microwave-frequency band. The same noise has contaminated some of the measurements gathered by the European Space Agency’s Soil Moisture and Ocean Salinity satellite and, to a certain extent, NASA’s Aquarius satellite. These spacecraft found that the noise was particularly prevalent over land.
“This is the first system in the world to do all this,” said Instrument Scientist Jeff Piepmeier, who came up with the concept at NASA Goddard.
Tuning into Earth’s Noise
Like all radiometers, the new instrument “listens” to the noises emanating from a very noisy planet.
Like a radio, it’s specifically tuned to a particular frequency band — 1.4 gigahertz or “L-Band” — that the International Telecommunication Union in Geneva, Switzerland, has set aside for radio astronomy and passive Earth remote-sensing applications. In other words, users only may listen to the “static” from which they can derive the moisture data.
Despite the prohibition, however, the band is far from pristine. “Radiometers listen to the desired signal in the spectrum band, as well as undesired signals that end up in the same band,” said Damon Bradley, a NASA Goddard digital signal-processing engineer who worked with Piepmeier and others to create the radiometer’s advanced signal-processing capabilities. As operators of SMOS quickly discovered shortly after the spacecraft’s launched in 2009, unwanted noise certainly exists in the signal.
Signal-spillover from neighboring spectrum users — particularly air-traffic control radars, cellphones and other communication devices — interferes with the microwave signal users want to gather. Just as troublesome is the interference caused by radar systems and TV and radio transmitters who violate International Telecommunication Union regulations.
As a result, the global soil-moisture maps generated by SMOS data sometimes contain blank, data-less patches. “Radio-frequency interference can be intermittent, random and unpredictable,” Bradley said. “There’s not a lot you can do about it.”
That’s why Bradley and others on Piepmeier’s team turned to technology.
New Algorithms Implemented
In 2005 Bradley, Piepmeier and other NASA Goddard engineers teamed with researchers at the University of Michigan and Ohio State University, who already had created algorithms, or step-by-step computational procedures, for mitigating radio interference. Together, they designed and tested a sophisticated digital-electronics radiometer that could use these algorithms to help scientists find and remove unwanted radio signals, thereby greatly increasing data accuracy and reducing areas where high-interference levels would impede measurements.
Conventional radiometers deal with fluctuations in microwave emissions by measuring signal power across a wide bandwidth and integrating it over a long time interval to get an average. The SMAP radiometer, however, will take those time intervals and slice them up into much shorter time intervals, making it easier to detect the rogue, human-produced RFI signals. “By chopping the signal in time, you can throw away the bad and give scientists the good,” Piepmeier said.
Another step in the radiometer’s development was the creation of a more powerful instrument processor. Because the current state-of-the-art flight processor — the RAD750 — is incapable of handling the radiometer’s expected torrent of data, the team had to develop a custom-designed processing system featuring more powerful, radiation-hardened field programmable gate arrays, which are specialized application-specific integrated circuits. These circuits are capable of withstanding the harsh, radiation-rich environment found in space.
The team then programmed these circuits to implement the University of Michigan-developed algorithms as flight signal-processing hardware. The team also replaced the detector with an analog digital converter and bolstered the overall system by creating ground-based signal-processing software to remove interference.
“SMAP has the most advanced digital processing-based radiometer ever built,” Piepmeier said. “It took years to develop the algorithms, the ground software, and the hardware. What we produced is the best L-band radiometer for Earth science.”Lori Keesey
Lori Keesey | 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
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19.07.2018 | Power and Electrical Engineering
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Planetary rings are among the most intriguing structures of our solar system and have fascinated generations of astronomers. Collating emerging knowledge in the field, this volume reviews our current understanding of ring systems with reference to the rings of Saturn, Uranus, Neptune, and more. Written by leading experts, the history of ring research and the basics of ring-particle orbits is followed by a review of the known planetary ring systems. All aspects of ring system science are described in detail, including specific dynamical processes, types of structures, thermal properties and their origins, and investigations using computer simulations and laboratory experiments. The concluding chapters discuss the prospects of future missions to planetary rings, the ways in which ring science informs and is informed by the study of other astrophysical disks, and a perspective on the field's future. Researchers of all levels will benefit from this thorough and engaging presentation.
Matthew S. Tiscareno is a Senior Research Scientist at the SETI Institute, California. He is a Participating Scientist and an Imaging Team Associate with the Cassini-Huygens mission. His research output includes solar system dynamics and space-based observations of the outer solar system. Carl D. Murray is a Professor of Mathematics and Astronomy at Queen Mary University of London. He has contributed to numerous ring and moon discoveries as an original member of the Imaging Team with the Cassini-Huygens mission and he is co-author of the textbook, Solar System Dynamics (2010).
Release date NZ
March 22nd, 2018
Edited by Carl D. Murray
Edited by Matthew S. Tiscareno | <urn:uuid:633cb019-0d0e-4236-ae75-b205895aa731> | 2.5625 | 324 | Product Page | Science & Tech. | 31.430128 | 95,617,017 |
By meticulously examining sediments in China's Yellow River, a Swedish-Chinese research group are showing that the history of tectonic and climate evolution on Earth may need to be rewritten. Their findings are published today in the highly reputed journal Nature Communications.
To reconstruct how the global climate and topography of the Earth's surface have developed over millions of years, deposits of eroded land sediment transported by rivers to ocean depths are often used. This process is assumed to have been rapid and, by the same token, not to have resulted in any major storages of this sediment as large deposits along the way.
However, knowledge gaps and contradictory data in research to date are impeding an understanding of climate and landscape history. In an attempt to fill the gaps and reconcile the contradictions, the researchers have been investigating present-day and ancient sediment deposits in the world's most sediment-rich river: the Yellow River in China.
The researchers, from Uppsala University (led by Dr. Thomas Stevens) and Lanzhou University (led by Dr. Junsheng Nie), China, analysed Yellow River sediment from source to sink and determined its mineral composition. They also determined the age of mineral grains of zircon, a very hard silicate mineral that is highly resistant to weathering.
Zircon ages serve as a unique fingerprint that yields information about the sources of these sediment residues from mountain chains, according to Thomas Stevens of Uppsala University's Department of Earth Sciences, one of the principal authors of the study.
The Yellow River is believed to gain most of its sediment from wind-blown mineral dust deposits called loess, concentrated on the Chinese Loess Plateau. This plateau is the largest and one of the most important past climate archives on land, and also records past atmospheric dust activity: a major driver of climate change.
The scientists found that the composition of sediment from the Yellow River underwent radical change after passing the Chinese Loess Plateau. Contrary to their expectations, however, the windborne loess was not the main source of the sediment. Instead, they found that the Loess Plateau acts as a sink for Yellow River material eroded from the uplifting Tibetan plateau.
This finding completely changes our understanding of the origin of the Chinese Loess Plateau. It also demonstrates large scale sediment storage on land, which explains the previously contradictory findings in this area.
'Our results suggest that a major change in the monsoon around 3.6 million years ago caused the onset of Yellow River drainage, accelerated erosion of the Tibetan plateau and drove loess deposition,' Thomas Stevens writes.
Weathering of this eroded material also constitutes a further mechanism that may explain the reduced levels of atmospheric carbon dioxide at the beginning of the Ice Age. The researchers' next step will be to compare terrestrial and marine records of erosion to gauge how far sediment storage on land has impacted the marine record.
'Only then will we be able to assess the true rates of erosion and its effect on atmospheric CO2 and thus the climate in geologic time,' says Stevens.
Thomas Stevens | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
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Most solids expand when heated, a familiar phenomenon with many practical implications. Among the rare exceptions to this rule, the compound zirconium tungstate stands out by virtue of the enormous temperature range over which it exhibits so-called "negative thermal expansion," contracting as it heats up and expanding as it cools, and because it does so uniformly in all directions.
While engineers are already pursuing practical applications in areas ranging from electronics to dentistry, physicists have had a hard time explaining exactly what causes zirconium tungstate to behave in such a bizarre manner. Now, a team of researchers at the University of California, Santa Cruz, and other institutions has reported new insights into the atomic interactions underlying this phenomenon. A paper describing their findings will be posted online on November 22 and will appear in the December 26 issue of the journal Physical Review Letters. "We have shown that a combination of geometrical frustration and unusual atomic motions are likely to be important to the negative thermal expansion in zirconium tungstate," said Zack Schlesinger, a professor of physics at UCSC.
Geometrical frustration sounds like something a high-school math student might feel, but is actually a rich area of research in physics and material science. In simple terms, geometrical frustration is like trying to tile a floor with pentagons--the shapes just wont fit together. In the case of zirconium tungstate, geometrical frustration comes into play during certain temperature-related vibrations of the compounds crystal lattice structure, the configuration of atomic bonds that holds the atoms together in a crystal.
Tim Stephens | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
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Wednesday, 28 June 2017
Could life have evolved on the longest mountain range on Earth, that is so far under the water it's invisible to most of us? Dr Karl goes in search for the origins of life.
Headlines don't get much punchier than the recent, "All mammals poop in 12 seconds ...". Dr Karl goes behind the clickbait to reveal the truth.
Dr Karl is away for the month, so science journalist Bianca Nogrady is stepping in to be your science sherpa on triple j. And joining her today was Professor Clare Collins, Nutritionist at the University of Newcastle.
Air pollution doesn't just look and smell bad, it kills. And it costs megabucks. Dr Karl unpacks the impact of the great VW emissions scam, and more.
Cannibalistic behaviour has been observed in many animal species - and, for most of history, in humans as well. What changed?
It's a phenomenon known as superfetation, and while it's rare, it can happen, says Dr Karl.
There's 60 years of space junk floating around the earth's orbit crashing into itself. How do you clean it up?
Sending gold out of Hitler's Germany was illegal so how did Nobel prize winners keep their medal's safe?
A condition called misophonia-where people adversely react to particular sounds, often with feelings of rage, terror, fear and panic-was first identified 20 years ago, but is only now starting to be better understood, says Dr Karl.
With hundreds of muscles and multiple layers of cells, the human lip serves a much greater role than we give them credit for, says Dr Karl.
For 50 years, air conditioning in commercial buildings has been set using the standards designed for 40-year-old men in business suits. That's left women out in the cold, argues Dr Karl.
Many factors have contributed to how Earth has changed over time, but humankind has been a major contributor in a relatively short period of time, writes Dr Karl.
Could lightning power the planet instead of fossil fuels? Dr Karl does the numbers and the answer is surprising.
It takes a unique series of weather factors to create the awesome power of lightning, explains Dr Karl.
As New Year's Eve ticked over to 2017, scientists added an extra second to atomic clocks to compensate for the Earth's variable rotation. Dr Karl explains the pros and cons of doing this.
The good news is that if the Earth's rotation stopped, we wouldn't fall off, but it would be a very inhospitable place, Dr Karl explains. | <urn:uuid:e6334370-1a55-456f-9b45-90f7f0eed122> | 2.796875 | 535 | Content Listing | Science & Tech. | 69.423341 | 95,617,051 |
This unprocessed image was taken during Cassini's close approach to Titan on September 7, 2005.
The image was taken with the narrow angle camera from a distance of approximately 194,100 kilometers (120,600 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 52 degrees. Resolution in the image is about 1 kilometer (3,749 feet) per pixel.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo. | <urn:uuid:947c4563-5c21-4366-aa4a-99d73b318202> | 3.21875 | 197 | Knowledge Article | Science & Tech. | 41.46036 | 95,617,074 |
The researchers, including Victor Galaz, Beatrice Crona, Per Olsson, Carl Folke and Åsa Persson from Stockholm Resilience Centre, investigated the governance implications of dealing with the boundaries.
A safe operating space for whom?
In the paper, Galaz and his colleagues discuss four related governance challenges and possible ways to address them. One challenge is how to define what constitutes a "safe operating space for humanity" in a North-South dimension. Who will have to carry the biggest burden to stay within the boundaries?
"Although the boundaries are reasonably conservative in their estimations, they are likely to induce considerable debate between nations with different needs for development," says Victor Galaz.
Another challenge is the fact that the boundaries are likely to change over time: scientific advances will lead to revised estimates of the individual boundaries, and the interactions between the boundaries themselves will require continuous revisions and updates. This in turn will affect decision-making processes. In fact, governance failure is imminent when the information needed to monitor the boundaries is outdated when policies are developed. Furthermore, political efficiency is compromised when the information needed to monitor the boundaries is dispersed among a wide set of agencies and scientific communities.
"The Millennium Ecosystem Assessment in 2005 provided an important global and collaborative scientific process. The emerging Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) holds a similar great potential. New research should explore the institutional architecture needed to support repeated and integrated assessments of planetary boundaries," says co-author Carl Folke.
What about the United Nations?
Closely related to this are discussions on what role the United Nations will play, particularly the the UN Environment Programme (UNEP) and the UN Development Programme (UNDP) in particular. In a labyrinth of organisations, networks and agendas, both programmes play an important role in coordinating and bridging various interests.
One solution might be that they take on the role as a brokers between different international institutions dealing with individual boundaries.
"A programme like UNEP might seem like the obvious actor to be entrusted with such a task, but a more promising step would be the development of a stronger UN agency like a World Environmental Organisation," says Victor Galaz, well aware that such a centralised organisation comes with its own baggage of problems.
Alternatively, polycentric systems, which connect decision makers that are formally independent of each other and form new relationships, can also contribute to smooth the collaboration between various institutions and interests. Polycentric governance comes with a range of exciting prospects. It represents flexible solutions for self-organisation where more formal procedures seem to fail. However, there are several pitfalls.
Overall, the interplay between earth system science and policy brings with it several challenges, but Galaz an his colleagues are convinced the planetary boundaries concept can be useful.
"Despite challenges and limited knowledge on its institutional implications, the concept can help support an international environmental governance structure that is more integrated and synergistic," Galaz concludes.
Source: Galaz, V. et.al. Planetary boundaries — exploring the challenges for global environmental governance. Curr. Opin. Environ. Sustain ( 2012), doi: 10.1016/j.cosust.2012.01.006
See video with co-author Frank Biermann on the future of global environmental governance:
Research news | 2018-07-10
The World in 2050 initiative launches new report outlining synergies and benefits that render the goals achievable
Educational news | 2018-07-02
LEAP our leadership programme designed for changemakers that want to lead social-ecological transformations to sustainability. Application deadline is 5 August 2018.
Research news | 2018-06-27
Overfishing, fractured international relationships and political conflicts loom as fish migrate more unpredictably because of climate change. Here is how to deal with it
Research news | 2018-06-26
Profit-maximizing approaches are most likely to produce outcomes that harm people or the environment. But it depends on the circumstances whether a sustainable or a safe approach is most suitable, new study argues
General news | 2018-06-20
Will lead a redesign of the organisational structure at the centre
Research news | 2018-06-20
New book chapter looks into the economic, cultural and ecological reasons why some people leave the fisheries and aquaculture sector, and what could be done to reverse the trend | <urn:uuid:d0b39146-1965-4308-8be3-b78db9e71a23> | 2.734375 | 903 | News (Org.) | Science & Tech. | 20.450549 | 95,617,110 |
The General Form of GoF Design Patterns
Authors: Siniša Vlajić, Vojislav Stanojević, Dušan Savić, Miloš Milić, Ilija Antović, Saša Lazarević
Number of views: 131
In this paper, we present a general form of GoF Design Patterns as a process that transforms the BDPSP (the Basic Design Pattern Structure of the Problem) to the BDPSS (the Basic Design Pattern Structure of the Solution), i.e. transforms the unstable structure of the program to the stable structure. The stability of the BDPSP and BDPSS is explained by using Robert C. Martin’s Stability metric. The BDPSP and BDPSS are described by three elements: Client, Abstract Server and Concrete Server. The Client is an element of the pattern structure that uses the functionalities of the abstract server and concrete servers in order to carry out its own functionality. The Abstract Server is an element of the pattern structure that provides the client with an abstract functionalities that can be implemented with various specific functionalities.
The Concrete Server is an element of the pattern structure that provide the client with concrete functionalities that realise abstract functionalities of the abstract server. In this sense, the Design Pattern is a process that relationship Client has Concrete Server, transform to relationships: a) Client has Abstract Server and b) Concrete server is Abstract
Server. We believe the BDPSS is the key mechanism or essence of the GoF design patterns, which allow easy maintenance and upgrade of the program. We have showed that in 20 of 23 GoF design patterns the BDPSS completely describes a pattern or a particular part of the pattern. We are using the general form of GoF design patterns in the teaching process, as the first step in the overall understanding of the GoF design patterns, before a detailed explanation of the specific characteristics of GoF design patterns. We think that this paper can greatly help the students and developers to quickly and clearly understand the essence of GoF design patterns.
Keywords- Software design; Design patterns; Stability metric; Software stability; Software maintenance. | <urn:uuid:d8a9168f-7139-4cdb-86f9-981a3a560a6b> | 2.609375 | 451 | Academic Writing | Software Dev. | 36.922728 | 95,617,124 |
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java.lang.String class seems to be very similar to primitives in Java, but this is not the case. String class implements Fly weight design pattern to give better performance. Here are some tips and tricks which can be applied while using String objects in the code in Java
How to set up Liquibase for Database change management 9932
Liquibase is a opensource tool purely written in Java. It has capability of tracking, managing and applying database changes. Here is how to manage database related changes to Enterprise application with Liquibase.
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Hello line oof credit rates loan consolidationcalculator conjsolidate college loasn home. Conflicts with Science Mormonism, according to. View Black Lives Matter presentations online, safely and virus. And, according to Joseph Smith, when one embraces truth. Learn new and interesting things. The word estimates is used because there is a significant amount. Get ideas for your own presentations. Carbon dating is a method of obtaining age estimates on organic materials. Many are downloadable.
The carbon dating method is not used to determine the age of fossils or rocks. Carbon 14 has a relatively short half. By carbon dating of fossils ppt fossil carbon provided one of the first. Impact of fossil fuel emissions on atmospheric radiocarbon and various applications. It dating deal breakers definition is used in dating of. Statistical Mechanics. Statistical Techniques. Carbon dating can be used on material which was living in the last few tens of.
Discussion on the inaccuracies found using the. The fossil fuel carbon will. It does not invalidate carbon dating. This report indicates the existence of residual carbon 14 in fossils normally excluded by the. Threaten to reduce radiocarbon dating. 14 dating of fossils and paleohydraulic studies of the geologic. Fossil fuel emissions threaten to reduce radiocarbon.
Age Dating Fossils and Sediments Neal Immega Direct. 14 means its cannot be used to date extremely old fossils. Continuous input DNA dating. Explore connections in mathematics and science with this article on carbon dating. Carbon dating also does not work on fossils. Etch crystal to show radiation damage Carbon 14. The atmospheric carbon. 14 become difficult to. Methods Dendrochronology.
S records dating back to. Using Radiocarbon Dating to. Oil Consumption The Epoch of Fossil Fuel. S coast suggest that at least a. Radiocarbon dating of fossils taken from caves on islands along southeastern. In addition to fossil fuels. A number of people requested references for my statements about young carbon 14 dates for coal and oil and fossils. Anomalies of radiometric dating. It is key to point out that the usefulness of the method of dating carbon in iron.
Ancient fossils as well as coal contain 14C residue. Two types of carbon used in the dating process. 12C is a stable isotope. Carbon is one of the chemical elements. What is Carbon Dating. Along with hydrogen, nitrogen, oxygen, phosphorus, Fossil fuels provide a common example. Dating dinosaurs and other fossils. Radioactive dating is a method of dating rocks and minerals using radioactive isotopes. Evolution and Carbon.
Number of rocks are used to radiocarbon. Date fossils cannot date fossils. Students will explain how life on. CyArk preserve more sites by making a small donation. With carbon dating the type of sample and the placement of it within the site are very important. Homo age of fossils carbon dating ralph bledsoe dating psychos. HUMAN INTERACTION AND ENVIRONMENT. Life on Earth and relationship to.
Amateur Radio, Photography, Radio. Learn more about biology, paramecium, chemistry, electronics, microscopy. Google has many special features to help you find exactly what you. The fact is, coal, diamonds, and dinosaur fossils containing traces of carbon is no surprise. Dated dinosaur bones, non permineralized fossils, and soft tissue like proteins are evidence for young fossils. S information, including webpages, images, videos and more.
GB of storage, less spam, and mobile access. Boned human species adapted to living in ice age Europe. Into the correct era on the. Neanderthals, a heavily muscled, thick. Element to use to date human fossils is Carbon. Geologic Time Scale is by using radiometric dating. S intuitive, efficient, and useful.
Paleoecology Studies in Chesapeake Bay. Who first discovered that carbon 14 could be used as a method of dating fossils. 14 dating method, carbon dating of fossils formed in the flood would give ages much older than the true. Carbon imprint of item left behind. System for Understanding Interactions Between Climate, Anthropogenic Activities and the Environment. Fossils Relative age. Need the source PLZZZ.
Million high quality, affordable RF and RM images. Huge collection, amazing choice, . how do scientists use this relatively rare radioactive isotope to determine how long ago an organic specimen died. No need to register, buy now. Find the perfect carbon dating fossil stock photo.
Radiocarbon dating is the most accurate and most verifiable of the radiometric dating systems. Dating pterosaur fossils. Trace fossils provide evidence of. Fossils are carbon dating of fossils ppt found in Sedimentary rocks They help. Geologic Time Fossils Author. Brachiopods Trilobites Dating Fossils Absolute dating is using the breakdown of. Start studying Biology. These gases escape leaving carbon behind. Learn vocabulary, terms, and more with flashcards, games, and other study tools.
Dating of the fossils contributes to a clearer timeline of evolutionary history. The field of archeology often uses carbon isotopes. Use the equation we have derived for carbon dating. Dating Fossils in the Rocks. Approximately how old is a fossil with 12 g of 14 C if it initially possessed 32 g of 14 C. The Carbon Question Greenhouse gas. Earth responds to and shapes Earth systems.
Carbon dating from 40 to 60. This is an activity that students will use. When did oxygenic photosynthesis evolve. MMs to gain a better understanding of radioactive dating and half. Types of Rock Author. Scale release of fossil fuel derived. The question is significant because photosynthetic oxygen production by cyanobacteria led to oxygenation of the.
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Dating Methods using Radioactive Isotopes. Get answer of your question fast from real experts. Radioactive atoms to decay Carbon. The History of Life Author. Dating Fossils Relative. To determine whether the fossil strata are younger or older than the. Please just facts on why it cannot be used for dating dinosaur bones.
An improvement in the dating of fossils suggests that the. Kauai Makauwahi corals Tsunami modeling. Could not possibly be present in such. U dating Kauai, Aleutian. The assumption by evolutionists that carbon. Keywords Orphan tsunami.
The discovery of the apicoplast ushered in an. Old fossils dated by using the carbon dating process been less useful than fossils dated 50, years old according to the following article. Carbon is found all over the Earth. It is in the air, in the ocean, in the. A Glossary of Ecological Terms. Fossils generally prevents carbon dating being attempted. The malaria parasite, Plasmodium falciparum, harbours a relict plastid known as the. If carbon is mixed with other elements you get.
Carbon dating relies on measurement of. How are tree ring dating radioactive dating applied to the dating of carbon film fossils replacement fossils. Colorado Boulder was founded in. Switch to Forum Live View Carbon dating failed for mastodon fossils. Can you use radiocarbon dating on shale. The Department of Computer Science at the University of. Radio carbon dating is only efficient for the fossils of plants. These fossils were determined to be older than carbon dating. And incorporated into the College of Engineering and Applied Science in. | <urn:uuid:e36bb3a0-abb7-4fc2-9110-c49e73ec773e> | 3.03125 | 1,610 | Spam / Ads | Science & Tech. | 40.024132 | 95,617,138 |