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FINDINGS: Researchers isolated bisdemethoxycurcumin, the active ingredient of curcuminoids – a natural substance found in turmeric root – that may help boost the immune system in clearing amyloid beta, a peptide that forms the plaques found in Alzheimer’s disease. Using blood samples from Alzheimer’s disease patients, researchers found that bisdemethoxycurcumin boosted immune cells called macrophages to clear amyloid beta. In addition, researchers identified the immune genes associated with this activity.
IMPACT: The study provides more insight into the role of the immune system in Alzheimer’s disease and points to a new treatment approach. Researchers say that it may be possible to test a patient’s immune response with a blood sample in order to individualize treatment. The genes involved in the process, called MGAT III and Toll-like receptors, are also responsible for a number of other key functions in the immune system. The results also suggest a new drug development approach for the disease that differs from the amyloid-beta vaccine. The new approach relies on the innate immune system, which is present at birth rather than on antibodies produced by B cells, which is a later developed part of the active immune system.
Rachel Champeau | EurekAlert!
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:387967ec-3151-4074-805a-d445bb33979b> | 2.609375 | 918 | Content Listing | Science & Tech. | 37.341516 | 95,585,258 |
The paper rectangle measuring 69 cm and 46 cm should be cut into as many squares as possible. Calculate the lengths of squares and their number.
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Find least common multiple of this two numbers: 140 175. | <urn:uuid:f1b9113a-0be4-4b3b-8264-58c8feea51a6> | 3.28125 | 650 | Tutorial | Science & Tech. | 79.961459 | 95,585,276 |
A new study shown that meteorite impacts on ancient oceans may have created nucleobases and amino acids. Researchers from Tohoku University, National Institute for Materials Science and Hiroshima University discovered this after conducting impact experiments simulating a meteorite hitting an ancient ocean (Fig. 1).
With precise analysis of the products recovered after impacts, the team found the formation of nucleobases and amino acids from inorganic compounds. The research is reported this week in the journal Earth and Planetary Science Letters.
Figure 1: These are chematics of nucleobases formation by meteorite impact on earth.
Dr. Yoshihiro Furukawa
All the genetic information of modern life is stored in DNA as sequences of nucleobases. However, formation of nucleobases from inorganic compounds available on prebiotic Earth had been considered to be difficult.
In 2009, this team reported the formation of the simplest amino acid, glycine, by simulating meteorite impacts. This time, they replaced the carbon source with bicarbonate and conducted hypervelocity impact experiments at 1 km/s using a single stage propellant gun (Figure 2).
They found the formation of a far larger variety of life's building blocks, including two kinds of nucleobases and nine kinds of proteinogenic amino acids. The results suggest a new route for how genetic molecules may have first formed on Earth.
Title: Nucleobases and amino acids formation through impacts of meteorites on the early ocean.
Authors: Furukawa Y., Nakazawa H., Sekine T., Kobayashi T., Kakegawa T.
Journal: Earth and Planetary Science Letters (2015), http://dx.
Dr. Yoshihiro Furukawa
Assistant Professor, Department of Earth Science, Tohoku University
Dr. Takamichi Koybayashi
Principal Researcher, Ultra-High Pressure Processes Group
Materials Processing Unit, National Institute for Materials Science
Dr. Toshimori Sekine
Professor, Department of Earth and Planetary System Science, Hiroshima University
Yoshihiro Furukawa | EurekAlert!
New research calculates capacity of North American forests to sequester carbon
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Scientists discover Earth's youngest banded iron formation in western China
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Materials Sciences
18.07.2018 | Life Sciences
18.07.2018 | Health and Medicine | <urn:uuid:2fbbc646-a5ba-4c02-9418-2ed54c7d63c1> | 3.6875 | 1,062 | Content Listing | Science & Tech. | 31.930322 | 95,585,292 |
The diagram shows an inclined slope, at an angle of 25 degrees, the mass of the object is 3kg, and the force acting up the slope is 24N
a) Calculate the acceleration of the block up the the slope, assuming no friction forces act on the slope
b) If the 24N force is removed, what would be the deceleration of the block?
c)As the block accelerates down the slope, the surface changes and a large force is eencountered so that the block moves with constant velocity. What is the magnitude of the fricton force that causes this motion?
For a) I got 3.85ms-2
b) I got 4.15ms-2
c) i got 1N
However i do not know if these answers are correct, thank you for your help, it would be a pleasure if you would work these out, with the correct values..
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Physics forces and acceleration up an inclined slope question watch
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- 29-10-2017 16:27 | <urn:uuid:7026b6f9-dfde-4c76-aa44-644dce0ee7df> | 3.34375 | 227 | Q&A Forum | Science & Tech. | 65.237941 | 95,585,296 |
If so, it allows it to be submitted to the server and (usually) saved in a database; if not, it gives you error messages to explain what you've done wrong (provided you've done it right).Form validation can be implemented in a number of different ways.The option of using pure HTML, sometimes with a touch of CSS, to complement Java Script form validation was until recently unthinkable.Sure there have been all kinds of whacky plug-ins over the years aimed at achieving this, but never a single standard that we could work towards.By using the hooks provided by this module, you can also define your own validation rules in your own modules.The following validation rules are currently included: A: You can validate against a whole range of things using the regular expressions validation rules, so we cannot give examples for every use case.He has been a featured speaker at many industry events including Microsoft Dev Days and the ASP. Shannon speaks and trains for companies such as App Dev ( and Learn It ( and has been a featured speaker in training videos with Learn Key. Data validation over the Web is performed in one of two locations: on the user's computer, or on the Web server.
A slightly negative aspect of validating data on the user's computer is that the validation is performed via a script residing in the Web page. You only have two possible scripting languages that you can use on a user's computer: VBScript or Java Script.Form validation helps us achieve these goals — this article tells you what you need to know.This is called form validation — when you enter data the web application checks it to see if it is correct.You could ask for some help in the issue queue with regards to your exact regular expression.There are already some examples available; have a look at Regular Expressions for Webform Validation (thx nfd) and for more examples. | <urn:uuid:43c0043a-c0ff-4bf7-8f41-7458f2012a6d> | 2.5625 | 382 | Documentation | Software Dev. | 45.842541 | 95,585,302 |
Poleward Flows off Mexico’s Pacific Coast
Poleward flows are predominant off the west coast of Mexico. Off the peninsula of Baja California, the northern third of the Mexican Pacific coastline, one finds the southern extension of the California Current System. Poleward flows in this region occupy a broad domain of about 200 km width, adjacent to the coast, and include an intensified countercurrent that can reach 50 cm s −1 , often within 20 km of the shelf and slope. From late winter to early summer, the upwelling favorable northwesterly winds oppose the poleward flow at the surface and the current proceeds as an undercurrent that hugs the continental slope. This poleward flow advects Subtropical Subsurface Water from the tip of Baja California into the Southern California Bight and farther north. The coast of mainland Mexico is exposed, on the contrary, to a broad extension of the equatorial return flow that feeds the North Equatorial Current from the Equatorial Countercurrent. This flow is known as the Costa Rica Coastal Current; it extends around the Costa Rica Dome, and northwestwards to the mouth of the Gulf of California, where the Eastern Pacific Transition Zone usually abutts the continent. This poleward flow is most prominent during the fall and may reverse directions in the spring, appearing as an intensified California Current extension. The strength of the large scale drifts, the surface expression of the counterflows, and the latitude at which the currents meet, all vary seasonally and depend on the intensity of the dominant winds. Direct observations of the poleward flows off Mexico are few and restricted to northern Baja California. They confirm a counterflow is probably present throughout the year, mostly over the shelf and slope regions, but with its surface expression obliterated by the upwelling favorable northwesterly winds that blow strongly in the late winter and spring. There are no direct measurements to provide a detailed description of the Costa Rica Coastal Current and, in particular, to know whether it possesses a counterflow.
KeywordsNorth Equatorial Current Intertropical Convergence Zone California Current South Equatorial Current Baja California Peninsula
Unable to display preview. Download preview PDF. | <urn:uuid:8af26b07-f86d-4696-ace9-39b325fecace> | 2.953125 | 447 | Truncated | Science & Tech. | 27.264915 | 95,585,304 |
A nephelometer has been developed for airborne measurement of polar scattering diagrams of atmospheric aerosols. The nephelometer light source is a modulated heliumneon laser; a digital synchronous photon counter is utilized to measure scattered-light intensity. The system has been designed for airborne measurements on a pressurized aircraft using outside air ducted through a 5-cm diameter airflow tube; the sample volume is that which is common to the intersection of the collimated source beam and the detector field of view within the airflow tube. The instrument has been flown on the NASA Convair 990 airborne laboratory to obtain data on the complex index of refraction of atmospheric aerosols. Particle sizing devices were operated simultaneously to determine the aerosol size-number distribution. Calculated values of the angular variation of scattered-light intensity were obtained by applying Mie scattering theory to the observed size distribution function and assuming different values of the complex index of refraction of the particles. The calculated values were then compared with data on the actual variation of the scattered-light intensity obtained with the polar nephelometer. The most probable value of the complex refractive index was taken to be that which provided the best fit between the experimental light-scattering data and the polar scattering diagrams calculated from the observed size distribution function.
G. W. Grams,
A. J. Dascher,
C. M. Wyman,
"Laser Polar Nephelometer for Airborne Measurements of Aerosol Optical Properties," Optical Engineering 14(1), 140185 (1 February 1975). https://doi.org/10.1117/12.7971772 | <urn:uuid:a17e8283-36cd-4640-874f-562fe3d2cbc2> | 3.203125 | 332 | Academic Writing | Science & Tech. | 30.559477 | 95,585,319 |
Coral spawning happening on reef
SOMETHING pretty special has been happening out at the Great Barrier Reef this week.
The coral has begun its spawning process.
Coral spawning is a once-a-year mass reproduction process which happens shortly after the full moon in November.
Local marine biologists have said that although it is often hard to pin point exactly when spawning takes place, they believe it happened on Saturday and Sunday.
Fantasea Adventure Cruising marine biologist Emily Smart said the coral relies on a number of factors to trigger the process.
She said the amount of moonlight and the temperature of the water were the most important things.
“It is a very good sign to see it happening,” she said.
“It is the only way that most corals reproduce genetically.”
When everything is right, the corals simultaneously release sperm and eggs into the water en masse over a few nights which look like small specks floating in the water.
This floats up to the surface and is often taken by other sea creatures for an easy meal, but when an egg is fertilised by the sperm it develops into what is called a planula larva. This can float around for days and can travel for hundreds of kilometres and may eventually settle on a reef far from where it was spawned.
After it settles, the coral polyp starts to bud and the coral colony begins to develop and grow.
This important process is one way the reef rejuvenates.
Generally less than one per cent of eggs released will survive to spawn them.
Ms Smart said although this may seem like an inefficient method of over saturation of eggs, it is a guarantee that at least some of the eggs will survive. | <urn:uuid:18d18fcb-198b-42ef-b22e-2be9195db3ba> | 3.3125 | 355 | News Article | Science & Tech. | 52.064005 | 95,585,321 |
posted by Sofia
A 0.509 g sample pure platinum metal was reacted with hcl to form 0.889 g of a compound containing only platinum and chlorine?
So the product must be of the form PtCln, and the question is what is n, the ratio of the chloride to platinum.
Moles of Pt: .509/atomicmassPt =.509/198=.00257
moles of Cl: (.889-.509)/atomicmassCl=.38/35.45=.0107
dividing each by the lowest, to get the ratio
Empirical formula: PtCl4 | <urn:uuid:99cbebc1-cd75-4144-b12a-b6acd8c3622d> | 2.6875 | 133 | Q&A Forum | Science & Tech. | 96.58375 | 95,585,325 |
If gasoline is spilled into a lake, an oil slick floating on the surface forms rapidly. What properties of alkanes are responsible for such oil slicks?© BrainMass Inc. brainmass.com July 23, 2018, 12:18 am ad1c9bdddf
Alkane properties like solubility, specific gravity, and viscosity are responsible for oil slicks in lakes. Alkanes are insoluble in water because the polar water molecules are not attracted to the ...
This solution explains which properties of alkanes are responsible for oil slicks on water surfaces. | <urn:uuid:55c27c73-1b5d-4fe8-9d88-fff857425119> | 2.71875 | 120 | Truncated | Science & Tech. | 40.76771 | 95,585,333 |
|Posted: Aug 03, 2012|
Supernova progenitor found?
|(Nanowerk News) Type Ia supernovae are violent stellar explosions. Observations of their brightness are used to determine distances in the universe and have shown scientists that the cosmos is expanding at an accelerating rate. But there is still too little known about the specifics of the processes by which these supernovae form. New research, led by Stella Kafka of the Carnegie Institution for Science in the United States, identifies a star system, prior to explosion, which will possibly become a type Ia supernova. The work will appear in the journal Monthly Notices of the Royal Astronomical Society ("QU Carinae: Supernova Ia in the making?").|
|The widely accepted theory is that type Ia supernovae are thermonuclear explosions of a white dwarf star that's part of a binary system—two stars that are physically close and orbit around a common centre of mass. The white dwarf has mass gradually donated to it by its companion. When the white dwarf mass eventually reaches 1.4 times that of the sun, it explodes to produce a type Ia supernova. The crucial questions are: What is the nature of the donor star and how does this white dwarf increase its mass. Also, how would that process affect the properties of the explosion?|
|A composite X-ray / optical / infrared image of the remnant of Tycho’s star, a type Ia supernova seen in 1572. (Image: NASA / CXC / SAO / JPL-Caltech / MPIA / Calar Alto / O. Krause et al.)|
|With these questions in mind, scientists have been searching for candidate systems that could become type Ia supernovae. There are thousands of possibilities in the candidate pool, none of which have yet been observed to produce an explosion. Recent studies, some of which involved scientists at Carnegie observatories, have identified sodium gas associated with type Ia supernovae. This gas might be ejected from the binary’s donor star and linger around the system to be detected after the white dwarf explodes. This provides a clue to the progenitor. Even so, Kafka still compared the search to “looking for a needle in a stellar haystack.”|
|Using data from the DuPont telescope of the Las Campanas observatory in Chile, Kafka and her team—Kent Honeycutt of Indiana University and Bob Williams of the Space Telescope Science Institute— looked at these gas signatures and were able to identify a binary star called QU Carinae as a possible supernova progenitor. It contains a white dwarf, which is accumulating mass from a giant star, and sodium has been detected around the system.|
|This star belongs to a small category of binaries that are very bright and in which the white dwarf accretes material from its companion at very high rates. Sodium should be produced in the atmosphere of the mass-donor giant star, and it can be ejected from the system via a stellar wind. If the white dwarf of this binary explodes into a supernova, the sodium would be detected with the same sort of signature as those found in other type Ia supernovae.|
|“We are really excited to have identified such a system,” Kafka said. “Understanding these systems, the nature of the two stars, the manner in which mass is exchanged, and their long-term evolution will give us a comprehensive picture on how binaries can create one of the most important explosions in the universe.”|
|Source: Royal Astronomical Society|
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Sometimes programs to use system error codes as exit codes. For example, Perl uses $! as as the error code when you call die. A quick and dirty way of finding the meaning of an system error number is to assign it to $^E.
$ perl -E'$^E=13; say $^E;' | <urn:uuid:8cafac9e-0101-4339-9e12-ca3a0b17427b> | 2.609375 | 69 | Documentation | Software Dev. | 73.544107 | 95,585,349 |
The Centre for Ecology and Hydrology and the Nature Locator team have joined forces to help map species of ladybird within the UK.
For hundreds of years people in Britain have been recording when and where they see plants, animals and other wildlife.
The Biological Records Centre within the Centre for Ecology & Hydrology helps people to record many different species by working with national recording schemes.
The UK Ladybird Survey is one such scheme. Launched in 1968, it collates and analyses records of ladybird species found across the UK, and maps their distributions.
The information gathered is used by scientists to see how wildlife is changing due to factors such as climate change and the arrival of new species.
Scientists could not do this work without the help of people across the UK, like you, reporting when and where they find a species. | <urn:uuid:10dce838-df26-4534-a65e-74be99120ba9> | 3.796875 | 169 | Knowledge Article | Science & Tech. | 42.930769 | 95,585,362 |
The team, led by the University of Cambridge, have invented a way to make polymer opal sheets on industrial scales, opening up applications ranging from smart clothing for people or buildings, to banknote security.
Some of the brightest colours in nature can be found in opal gemstones, butterfly wings and beetles. These materials get their colour not from dyes or pigments, but from the systematically-ordered microstructures they contain.
The team behind the current research, based at Cambridge’s Cavendish Laboratory, have been working on methods of artificially recreating this ‘structural colour’ for several years, but to date, it has been difficult to make these materials using techniques that are cheap enough to allow their widespread use.
In order to make the polymer opals, the team starts by growing vats of transparent plastic nano-spheres. Each tiny sphere is solid in the middle but sticky on the outside. The spheres are then dried out into a congealed mass. By bending sheets containing a sandwich of these spheres around successive rollers the balls are magically forced into perfectly arranged stacks, by which stage they have intense colour.
By changing the sizes of the starting nano-spheres, different colours (or wavelengths) of light are reflected. And since the material has a rubber-like consistency, when it is twisted and stretched, the spacing between the spheres changes, causing the material to change colour. When stretched, the material shifts into the blue range of the spectrum, and when compressed, the colour shifts towards red. When released, the material returns to its original colour. Such chameleon materials could find their way into colour-changing wallpapers, or building coatings that reflect away infrared thermal radiation.
“Finding a way to coax objects a billionth of a metre across into perfect formation over kilometre scales is a miracle,” said Professor Jeremy Baumberg, the paper’s senior author. “But spheres are only the first step, as it should be applicable to more complex architectures on tiny scales.”
In order to make polymer opals in large quantities, the team first needed to understand their internal structure so that it could be replicated. Using a variety of techniques, including electron microscopy, x-ray scattering, rheology and optical spectroscopy, the researchers were able to see the three-dimensional position of the spheres within the material, measure how the spheres slide past each other, and how the colours change.
“It’s wonderful to finally understand the secrets of these attractive films,” said PhD student Qibin Zhao, the paper’s lead author.
Cambridge Enterprise, the University’s commercialisation arm which is helping to commercialise the material, has been contacted by more than 100 companies interested in using polymer opals, and a new spin-out Phomera Technologies has been founded. Phomera will look at ways of scaling up production of polymer opals, as well as selling the material to potential buyers. Possible applications the company is considering include coatings for buildings to reflect heat, smart clothing and footwear, or for banknote security and packaging applications.
The research is funded as part of a UK Engineering and Physical Sciences Research Council (EPSRC) investment in the Cambridge NanoPhotonics Centre, as well as the European Research Council (ERC). | <urn:uuid:3c646617-60e6-4d3b-96f0-8098f86f46aa> | 3.890625 | 690 | News Article | Science & Tech. | 30.102727 | 95,585,364 |
- Research article
- Open Access
Effects of protonation on the hydrolysis of triphosphate in vacuum and the implications for catalysis by nucleotide hydrolyzing enzymes
© The Author(s). 2016
Received: 29 February 2016
Accepted: 14 June 2016
Published: 29 June 2016
Nucleoside triphosphate (NTP) hydrolysis is a key reaction in biology. It involves breaking two very stable bonds (one P–O bond and one O–H bond of water), in either a concurrent or a sequential way. Here, we systematically examine how protonation of the triphosphate affects the mechanism of hydrolysis.
The hydrolysis reaction of methyl triphosphate in vacuum is computed with protons in various numbers and position on the three phosphate groups. Protonation is seen to have a strong catalytic effect, with the reaction mechanism depending highly on the protonation pattern.
This dependence is apparently complicated, but is shown to obey a well-defined set of rules: Protonation of the α- and β-phosphate groups favors a sequential hydrolysis mechanism, whereas γ-protonation favors a concurrent mechanism, the two effects competing with each other in cases of simultaneous protonation. The rate-limiting step is always the breakup of the water molecule while it attacks the γ-phosphorus, and its barrier is lowered by γ-protonation. This step has significantly lower barriers in the sequential reactions, because the dissociated γ-metaphosphate intermediate (PγO3 −) is a much better target for water attack than the un-dissociated γ-phosphate (−PγO4 2−). The simple chemical logic behind these rules helps to better understand the catalytic strategy used by NTPase enzymes, as illustrated here for the catalytic pocket of myosin.
A set of rules was determined that describes how protonating the phosphate groups affects the hydrolysis mechanism of methyl triphosphate: Protonation of the α- and/or β- phosphate groups promotes a sequential mechanism in which P-O bond breaking precedes the breakup of the attacking water, whereas protonation of the γ-phosphate promotes a concurrent mechanism and lowers the rate-limiting barrier of water breakup. The role played by individual protein residues in the catalytic pocket of triphosphate hydrolysing enzymes can be assigned accordingly.
In the catalytic pocket of NTPase enzymes, many partial positive charges surround the triphosphate moiety of NTP. Figure 2a shows, for example, the active site of myosin with ATP bound in the catalytically competent conformation. The many hydrogen bonds donated by the NH moieties of the P-loop (for “phosphate-binding” loop) to the triphosphate moiety are seen in all NTPase binding sites. The positive electrostatic environment is further enhanced by Lys185 and H-bond donor Asn233 (Fig. 2a). These lysine, [11–13] and aspargine (replaced by an arginine in some NTPases) [12, 15–17] residues are critical for the catalytic function of NTPases, as evidenced from kinetic and mutagenesis studies. To differentiate how interactions between this electrostatically positive environment and the three individual phosphate groups affects the hydrolytic mechanism and its energy barrier, we are studying here the effect of placing protons on triphosphate in vacuum, varying the number of such protons and their oxygen location on the triphosphate. This reveals that the location of the protons has a strong influence on the catalytic mechanism. We derive a simple set of chemical rules, which explain this effect and can be related to the catalytic strategy used by NTPases.
Triphosphate tends to chelate Mg2+ in solution, and in the enzymes, NTPs are always found with one Mg2+ complexed between the β- and γ-phosphates. Therefore, it is important to study the triphosphate bound to Mg2+, which should be fully coordinated. The pKa value of the reaction [HATP3- → ATP4- + H+] is 6.95 at 25Co in the absence of magnesium . The presence of magnesium makes this pKa drop by about 2 units (for example to 5.36 at 70Co) . This means that the Mg/ATP complex is fully deprotonated in water, and therefore easily binds as Mg2+/ATP4− to the enzymes. In the present study, only the triphosphate moiety of NTP is considered, using methyl triphosphate as a substrate analogue (Fig. 1, left panel). Five water molecules are present: one attacking (lytic) water Wa placed apically relative to the γ-phosphate, and four water molecules complete the coordination shell of the Mg2+. It can be seen in Fig. 2b that the energy-optimized conformation of this complex in vacuum is very similar to the conformation of the corresponding moiety of NTP in the enzymes (compare with Fig. 2a). Protonation states with up to three protons on the triphosphate were considered: A single proton was placed on either triphosphate oxygen α, β or γ (see Fig. 1a for atomic nomenclature). In the doubly protonated triphosphate, two protons were placed on either the αβ-, αγ-, or βγ-oxygens. In the triply protonated case, the three protons are on oxygens α, β and γ (named here “αβγ” protonation). Together with the un-protonated (zero protons) case, a total of eight protonation states were investigated here. For each of these protonation states, it was attempted to obtain both a concurrent and a sequential reaction. Using the AM1/d quantum method, (with parameters optimized for the treatment of phosphates chelating magnesium, see Methods), minimum energy paths (MEPs) were computed for each reaction. The MEPs give a complete description of the process, in terms of both mechanism and rate limiting energy barrier, and yield a molecular movie of each hydrolysis reaction (available in Additional file 1).
Our results show that the mechanism of hydrolysis is very dependent on the location of the protons on the triphosphate: Protonation of the α- and β-phosphate groups favors the sequential mechanism, whereas protonation on the γ-phosphate favors a concurrent reaction. This can be explained in terms of the charge shifts that occur during these different reaction mechanisms. Overall, the lowest barriers are achieved with the sequential mechanism, which can be explained by the fact that the dissociated PγO3 − metaphosphate intermediate (Fig. 2d) is a better target for the subsequent attack by the lytic water Wa than the –PγO4 2− group in the concurrent reaction (Fig. 1). This is consistent with the catalytic mechanism in NTPases, which has been shown to proceed via a sequential reaction [7, 21–26]. The present results help to explain why the many H-bonds made by the P-loop to the α- and β-phosphates of the NTP favor such a sequential mechanism in NTPases.
Effect of protonation on the barrier ΔEǂ of the concurrent reaction [a]
nP = 0
nP = 1
nP = 2
nP = 3
Effect of protonation on the barriers of the sequential reaction [a]
ΔE 1 ǂ [c]
E meta [d]
E 2 [e]
ΔE 2 ǂ [f]
Unprotonated case (np = 0)
Single protonation (nP = 1)
The energy profile of the concurrent MEP obtained with one proton placed on the γ-phosphate is plotted in Fig. 3b. The rate limiting energy barrier is 32.4 kcal mol−1 (located 27 % along the MEP) and its structure is shown in Fig. 4b. In spite of the fact that this structure and the reaction (see Additional file 3: Movie C2) are very similar to the un-protonated concurrent case (compare Fig. 4a and b), adding a proton on the γ-phosphate significantly lowers (by 11.6 kcal mol−1, Table 1) the activation barrier of concurrent hydrolysis. This can be explained by the fact that the protonated γ-phosphate (−OPγO3H−) bears one less negative charge than the un-protonated –OPγO3 2−, so that its repulsion with the partial negative charge on oxygen Oa of water Wa is diminished. In the cases of single protonation on either the α- or β-phosphates, it was not possible to isolate concurrent MEPs. In spite of using initial constraints, the MEPs always reverted to a sequential reaction (presented below).
Double protonation (nP = 2)
The energy profiles of the concurrent reaction obtained with two protons placed on the αγ- or βγ-phosphates are plotted in Fig. 3c. Structurally, these reactions proceed (Additional file 4: Movie C3 and Additional file 5: Movie C4) very similarly to the un-protonated and the γ-protonated concurrent cases. Their transition state structures (Fig. 4c and d, respectively) are very similar to the other concurrent transition states (Fig. 4). Their energy barriers (34.5 kcal mol−1 for αγ and 35.1 kcal mol−1 for βγ) are slightly higher (2–3 kcal mol-1, Table 1) than the barrier of the singly protonated case. This may be explained by the fact that α- or β-protonation favors a dissociation of the γ-phosphate (as will be shown below), which involves larger Pγ-Oβγ distances than those of the concurrent transition state for single γ-protonation. Indeed, the Pγ–Oβγ distance is 1.58 Å and 1.60 Å for the αγ and βγ protonation, respectively, slightly larger than the 1.57 Å for single γ-protonation (Fig. 4). Thus, adding α- or β-protons on the concurrent transition states raises the barrier relative to the singly γ-protonated triphosphate. For the same reason, double protonation on the αβ phosphates always resulted in a sequential MEP, in spite of attempts to use initial constraints towards a concurrent reaction.
Triple protonation (nP = 3)
The energy profile of the concurrent MEP with triply (α,β,γ) protonated triphosphate is plotted in Fig. 3e. The transition state (Fig. 4e) has an even larger Pγ–Oβγ distance (1.63 Å) than the αγ or βγ doubly protonated transition states (Fig. 4c and d). The unfavorable effect of the α and β protons on the concurrent energy barrier (described above) is more than cumulative, since it is 7.5 kcal mol-1 higher than for single γ-protonation (Table 1). Additional file 6: Movie C5 shows the structural changes during this reaction.
Inter-atomic distances [Å] in the saddle point of metaphosphate formation [a]
Unprotonated case (nP = 0)
The energy profile of the sequential MEP obtained without protons on the triphosphate is plotted in Fig. 3a. Barrier ΔE 1 ǂ is 14.1 kcal mol−1 at λ = 57 %. The energy of the metaphosphate intermediate is E meta = 11.2 kcal mol−1, so that the second barrier (at λ = 64 %) is ΔE 2 ǂ = 45.9-11.2 = 34.7 kcal mol−1 (Table 2). Thus, step 1 (the breaking of the Pγ-Oβγ bond) has a much lower barrier than step 2 (water attack). This turns out to be the case for all other sequential MEPs (see Table 2). The transition state for step 2 is shown in Fig. 5a, in which the planar PγO3 − molecule is clearly recognizable and the Oa–Pγ distance is short at 2.3 Å. The sequentiality of step 1 and step 2 can be seen in Additional file 7: Movie S1. Relative to the reactant, the energy (E 2 = 45.9 kcal mol−1) of the rate-limiting transition state is similar to that of the un-protonated concurrent reaction (ΔE ǂ = 44.0 kcal mol−1, Table 1). Thus, in absence of protons, there is no clear preference for either the concurrent or the sequential mechanism of hydrolysis.
Single protonation (nP = 1)
The energy profiles of the sequential MEP obtained with one proton placed on either the α- or the β-phosphate are plotted in Fig. 3b. In both cases, the effect of these protonations on the barrier of the first step (Pγ-Oβγ bond breaking) is very strong, lowering ΔE 1 ǂ by ~12 kcal mol−1 relative to the un-protonated case: ΔE 1 ǂ = 1.82 kcal mol−1 (at λ = 9 %) for α- and ΔE 1 ǂ = 1.99 kcal mol−1 (at λ = 4 %) for β-protonation (Table 2). Such low barriers mean that the dissociation of the Pγ–Oβγ bond is nearly unhindered at room temperature when the triphosphate is protonated on the α- or β-positions, a remarkable result. Moreover, the resulting metaphosphate intermediates are more stable than the reactant state (E meta < 0, Table 2).
How can protonation of the αβ-diphosphate moiety promote metaphosphate dissociation in such a dramatic way? The answer lies in the change of charge distribution upon dissociation: For example, in the un-protonated triphosphate reactant, two formal negative charges are located on the γ-phosphate (-OPγO3 2−) and two negative charges are on the αβ-diphosphate moiety (Fig. 2c). In the metaphosphate intermediate, the PγO3 − bears a single negative charge and the αβ-diphosphate has three negative charges (Fig. 2d). Thus, one negative charge shifts from the γ- to the αβ-phosphates upon dissociation. This charge shift is strongly favored when a positive charge (H+) is placed onto the αβ-moiety.
The barrier of step 2 (breaking of water Wa) is ΔE 2 ǂ = 37.5 kcal mol−1 for α- and ΔE 2 ǂ = 31.4 kcal mol−1 for β-protonation (Table 2), which is similar to that of the un-protonated case (ΔE 2 ǂ = 34.7 kcal mol-1). This indicates that the effect of these protonations on step 2 is limited, as would be expected from the fact that the αβ-moiety is no longer covalently bound to the γ-phosphate when the later gets attacked by water Wa (see the corresponding transition states in Fig. 5b and c). Note that it is difficult to compare the energy of the metaphosphate intermediate (E meta) of the α- and β-cases, due to the large conformational change that occurs (from λ = 21 to 58 %) after metaphosphate formation in the β-case (compare Additional file 8: Movie S2 and Additional file 9: Movie S3).
All attempts to obtain a sequential MEP with one proton placed on the γ-phosphate failed, because the reaction always became concurrent. This effect can be explained in terms of the above mentioned charge shift: Placing a positive charge (H+) on the γ-phosphate strongly disfavors the shift of the negative charge from the γ- to the αβ-moiety (Fig. 2c → d) that needs to take place upon metaphosphate dissociation. Therefore, placing a proton on the γ-phosphate destabilizes the metaphosphate so much, that the “transition state” of step 1 is no longer a saddle-point on the energy surface (consequently, a MEP can not be found).
Double protonation (nP = 2)
Placing two protons on the αβ-moiety (one on the α-, the other on the β-phosphate) favors the shift of negative charge from the γ- to αβ-phosphates even more than a single proton. Not surprisingly, the barrier of metaphosphate dissociation drops even lower in this case, ΔE 1 ǂ = 0.34 kcal mol−1 (Table 2). The corresponding energy profile is plotted in Fig. 3d, where this barrier (located at λ = 2 %) can be seen to be so low that the first step is essentially barrier-less. After some rearrangements of the metaphosphate intermediate (from λ = 2 to 35 %, see also Additional file 10: Movie S4), the barrier of step 2 (breaking of water Wa) is ΔE 2 ǂ = 29.2 kcal mol−1 (transition state shown in Fig. 5d), which is similar to the value obtained for single protonation on β (ΔE 2 ǂ = 31.4 kcal mol−1, Table 2) and confirms that protonation of the αβ-moiety does not significantly affect step 2 of the sequential reactions.
Double protonation on the αγ- or βγ-phosphates has a very different effect than the double protonation of the αβ-moiety described above, as can be seen by comparing their three energy profiles (Fig. 3d). Indeed, the resulting barrier for step 1 is ΔE 1 ǂ = 14.5 kcal mol−1 for αγ-protonation, as high as for step 1 in the un-protonated case (ΔE 1 ǂ = 14.2 kcal mol−1 Table 2), and much higher than for the singly α-protonated case (ΔE 1 ǂ = 1.82 kcal mol−1). Thus, protonation on the γ-phosphate counteracts the promoting effect of α-protonation on the metaphosphate dissociation step. As described above, this is due to the unfavorable effect of the positive charge (H+) on the γ-position, which opposes the charge shift from the γ- to the αβ-moieties, thereby suppressing the favorable effect of α-protonation. The same behavior happens for double protonation on βγ, for which ΔE 1 ǂ = 8.02 kcal mol−1 (Table 2). This is not as high as for αγ-protonation, but still significantly higher than the single β-protonation (ΔE 1 ǂ = 2.0 kcal mol-1, Table 2). The fact that βγ- has a smaller ΔE 1 ǂ than αγ-protonation shows that the promoting effect on dissociation is stronger for protonation on the β-phosphate than on the α-phosphate. This is not surprising, since the formal charge change upon dissociation is larger on the β-phosphate (1e → 2e) than on the α-phosphate (1e → 1e), as illustrated by the charge distributions of Fig. 2c and d.
The ΔE 2 ǂ barrier of step 2 (Wa water attack) is lower for the αγ- and βγ-cases, 27.0 and 25.3 kcal mol-1 respectively (for structures shown in Fig. 5e and f), than for single protonation on α or β (37.5 and 31.4 kcal mol−1 respectively, see Table 2). The reason for this is the same as the one given above to explain barrier lowering in the concurrent singly γ-protonated case: The presence of a γ-proton leads to a dissociated metaphosphate in the neutral HPγO3 form (instead of the negatively charged PγO3 - form). This generates less repulsive interactions with the partial negative charge on oxygen Oa of water Wa when it attacks this neutral metaphosphate in step 2. Thus, just as seen in the concurrent reactions, having a proton on the γ-phosphate facilitates the activation of water Wa when it attacks the γ-phosphorus. Additional file 11: Movie S5 and Additional file 12: Movie S6 show the sequential αγ- and βγ-reactions, respectively.
Triple protonation (nP = 3)
The energy profile of the sequential MEP with a triply (α,β,γ) protonated triphosphate is plotted in Fig. 3e. The first barrier ΔE 1 ǂ = 4.9 kcal mol−1 (Table 2) is the result of a compromise between the favorable (i.e. decreasing ΔE 1 ǂ) effect of having two protons on the αβ-moiety (which favors the charge shift in Fig. 2c → d), and the unfavorable (i.e. raising ΔE 1 ǂ) effect of having a proton on the γ-phosphate (which disfavors the charge shift).
The transition state of step 2 (Fig. 5g) gives a barrier ΔE 2 ǂ = 21.9 kcal mol−1. This is the lowest of all ΔE 2 ǂ values (Table 2), which can be related to the fact that an increase in the total number of protons (i.e., a decrease in the net negative charge) on the triphosphate leads to less repulsion with the OaH− group that attacks the γ-phosphorus in step 2. Indeed, the values of ΔE 2 ǂ gradually drop as one looks down the right column of Table 2. Overall, the triply protonated sequential MEP has the lowest rate limiting barrier of all paths examined here, and is shown in Additional file 13: Movie S7.
Principle effects of (α, β or γ)-protonation
α- and/or β-protonation favor the sequential reactionWhen a single or two protons are placed on the α- and/or β-positions, hydrolysis is found to occur only via the sequential mechanism. Concurrent transition states can’t be located for protonation cases α, β or αβ. The energy barrier for Pγ–Oβγ bond breaking, ΔE 1 ǂ, is considerably lower for protonation cases α, β (ΔE 1 ǂ ~ 2 kcal mol−1) and αβ (ΔE 1 ǂ ~ 0.34 kcal mol−1) than for the dissociation barrier of the un-protonated case (ΔE 1 ǂ = 14.2 kcal mol−1), see Fig. 6a. All this shows that Pγ–Oβγ bond dissociation is strongly favored when protons are added onto α or β positions. This is because α- and/or β-protonation favors the negative charge shift from the γ-phosphate to the α,β-diphosphate upon Pγ–Oβγ bond breaking (Fig. 2c → d): In un-protonated triphosphate, two formal negative charges reside on the αβ-diphosphate and two negative charges on the γ-phosphate. After Pγ–Oβγ bond cleavage, the αβ-diphosphate moiety bears three negative charges and the γ-metaphosphate has one negative charge. The positive charge of a proton placed either on an α or a β oxygen atom of triphosphate pulls the electron density away from the γ-phosphate group and towards the αβ-diphosphate moiety. This prepares for the electronic distribution of the dissociated metaphosphate state, thus explains the large reduction in the ΔE 1 ǂ energy barrier. This stabilization effect is so strong that the resulting metaphosphate state constitutes a stable intermediate in the energy profile of all sequential reactions (see Fig. 3). The energy E meta of this intermediate is lower than the reactant (E meta < 0) for all cases of protonation on exclusively α- and/or β-groups (Table 2). As is expected from the formal charge distribution of the dissociated state (Fig. 2d), this pulling effect on the electron-density towards the αβ-diphosphate is somewhat stronger for β-protonation than for α-protonation (lower values of E meta for β-protonation in Table 2).
γ-protonation disfavors the sequential reaction
The effect of γ-protonation is the opposite of the effect of α/β-protonation and raises the ΔE 1 ǂ energy barrier of Pγ–Oβγ bond cleavage. When a γ-proton is added to an α-protonated triphosphate, ΔE 1 ǂ raises from 1.82 kcal mol−1 to 14.5 kcal mol−1 (Fig. 6a). A similar trend is observed when the γ-proton is added onto the β-protonated triphosphate (with ΔE 1 ǂ raising from 1.99 kcal mol−1 to 8.02 kcal mol−1), or when added to the αβ-protonated triphosphate (ΔE 1 ǂ increases from 0.34 kcal mol−1 to 4.9 kcal mol−1), see Fig. 6a. Again, this disfavoring effect of γ-protonation on Pγ–Oβγ bond breaking is explained by the charge-shift during Pγ–Oβγ bond cleavage. The positive charge of the γ-proton hinders the shift of the negative charge from the γ-phosphate to the αβ-diphosphate (Fig. 2c → d), thus disfavoring dissociation and raising ΔE 1 ǂ. This effect is strongest in absence of any protons on α and β. In that case, a single proton on γ-position even abolishes the sequential reaction (as mentioned in Results, a stable transition state can not be found).
Conversely, γ-protonation is necessary to be able to observe a concurrent reaction at all. Indeed, all concurrent paths with protonated triphosphate have a proton on the γ-phosphate (Table 1). In absence of γ-proton, these MEPs all revert to the sequential mechanism. For example, there is no concurrent MEP for singly α-protonated triphosphate, but a concurrent reaction can be found for the αγ-protonated case (Table 1). The same effect is observed for adding a γ-proton to β-protonated triphosphate, or for adding a γ-proton to the αβ-protonated triphosphate. Thus, adding a γ-proton alters the potential energy surface in such a way that the concurrent mechanism becomes feasible.
γ-protonation favors the breakup of water Wa
For the sequential reactions, γ-protonation lowers the activation barrier ΔE 2 ǂ of water attack: For example, the ΔE 2 ǂ of α-protonated triphosphate decreases from 37.5 to 27.0 kcal mol−1 in αγ-protonated triphosphate, a reduction of 10.5 kcal mol−1 upon addition of the γ-proton (see Fig. 6b). Similarly, ΔE 2 ǂ of β-protonated methyl triphosphate (31.4 kcal mol−1) reduces to 25.3 kcal mol−1 upon addition of the γ-proton, and addition of the γ-proton to αβ-protonated triphosphate reduces the barrier from 29.2 to 21.9 kcal mol−1 (Fig. 6b). The reason for this effect is that γ-protonation yields a neutral metaphosphate intermediate of the form HPγO3. It is not negatively charged (unlike the un-protonated PγO3 −), which reduces the electrostatic repulsion between the partial negative charge on oxygen Oa of water Wa and the γ-metaphosphate. Therefore, the γ-protonated metaphosphate is a better target for nucleophilic attack by Wa (and its accompanying breakup) than the un-protonated PO3 −. The same effect is at work in the concurrent reactions, where all reactions for triphosphate with a γ-proton can be seen (in Table 1) to have a lower activation barrier ΔE ǂ than the un-protonated (nP = 0) case (ΔE ǂ = 44 kcal mol−1). Thus, for both concurrent and sequential mechanisms, protonation in the γ-position lowers the energy barrier of water breakup and attack.
The sequential mechanism yields lower rate-limiting barriers
Even though ΔE 2 ǂ (the barrier of the second step in sequential pathways) is always higher than the ΔE 1 ǂ barrier (i.e., ΔE 2 ǂ > ΔE 1 ǂ, see Table 2), ΔE 2 ǂ is always lower than the rate-limiting barrier ΔE ǂ of the corresponding (i.e., for a given protonation state) concurrent pathway (compare Tables 1 and 2). For example for αγ-protonation, the sequential ΔE 2 ǂ (=27.0 kcal mol−1) is 7.5 kcal mol−1 lower than the concurrent ΔE ǂ (=34.5 kcal mol−1). Likewise for the un-protonated case (nP = 0), where ΔE 2 ǂ (=35 kcal mol-1) is 9 kcal mol−1 less than ΔE ǂ (=44 kcal mol−1). This ΔE 2 ǂ < ΔE ǂ rule applies also in the other protonation cases, βγ and αβγ. One explanation is that the metaphosphate molecule PγO3 − (or HPγO3 if γ–phosphate was protonated) generated by dissociation step 1 (Fig. 2c) is a much better target for water Wa than the –OPγO3 2- (or –OPγO3H-) group of un-dissociated triphosphate, for two reasons: a) The metaphosphate is planar, a geometry that allows closer approach of the attacking water Wa than the tetrahedral –O–PO3 group. b) The metaphosphate has one less negative charge than the un-dissociated –OPO3 group (for a given protonation of the γ-phosphate), thus generating less electrostatic repulsion with the negative partial charge on oxygen Oa of water Wa. The other reason for having ΔE 2 ǂ < ΔE ǂ is that in the concurrent mechanism, the energetic cost of the breaking water Wa and breaking the PγOβγ bond are paid simultaneously in a single transition state, while in the sequential mechanism, these costs are spread over two transition states.
Implications for triphosphate hydrolysis in enzymes
There are clear parallels between the hydrolytic reaction in enzymes and the αβγ-protonation case described above in terms of the resulting sequential mechanism and the respective energy barriers: The lowest barrier of hydrolysis in vacuum is obtained here when all three phosphates (α,β,γ) of triphosphate are protonated, with a sequential mechanism (ΔE 1 ǂ = 4.9 kcal mol−1 and ΔE 2 ǂ = 21.9 kcal mol−1). Likewise, it has been shown recently for several NTPases (myosin, [7, 21] kinesin, F1-ATPase, RAS-GAP [27, 28] ) that they all have a catalytic mechanism that is sequential, involving the initial formation of a PγO3 − metaphosphate, followed by the attack of the lytic water (which is always placed like Wa in Fig. 2a and b). This similarity is not due to protonation of the phosphates in the enzyme (computational studies indicate that the triphosphate is fully deprotonated when bound in the catalytic pocket), but arises because interaction of each phosphate group with its positively charged protein environment promotes similar charge-shifts within the triphosphate as those described above for the protonation in vacuum. For example in myosin, the six hydrogen bonds of the P-loop are all made to the αβ-phosphates (see Fig. 2a), thus pulling negative charge away from the Pβ-Oβγ bond. This is likely to have a similar lowering effect on the ΔE 1 ǂ barrier as the charge shift induced by the protonation on the α and/or β phosphates (which lowers ΔE 1 ǂ by 12–14 kcal mol−1, see Fig. 6a). The three H-bonds donated to the γ-phosphate by the Ser181 side chain and the backbone of Ser236 and Gly457 (Fig. 2a) make the γ-phosphorus become a better target for nucleophilic attack by water Wa, probably contributing to the lowering of ΔE 2 ǂ in the enzyme in a similar way as protonation of the γ-phosphates (which lowers ΔE 2 ǂ by 6–10 kcal mol-1, see Fig. 6b). A crude estimate of the amount of positive charge placed in direct contact with the triphosphate in myosin can be made: the nine H-bonds and Lys185+ amount to approximately +3.25 charges (counting ~0.25 charge per H-bond, which is the typical partial atomic charge on a proton of backbone NH groups in classical force-fields) . Of course this number is not a true net charge (it neglects the counter-charge of each H-bond dipole), but it is close to the +3 charge of three protons distributed onto the α-, β- and γ-protonated triphosphate. Thus it is not surprising that the ΔE 1 ǂ barrier obtained for myosin (8.7 kcal mol−1) is nearly as low as the ΔE 1 ǂ obtained with triply protonated triphosphate in vacuum (4.9 kcal mol−1).
In the present vacuum simulations, the proton abstracted from Wa was transferred to the γ-phosphate (in both the concurrent and sequential reactions). Thus the γ-phosphate serves as both the proton acceptor and as the general base that activates water Wa. In the enzymes, the final acceptor of the proton is also the dissociated γ-phosphate, but the NTPases utilize an external catalytic base (e.g., Glu459 in myosin, see Fig. 2a) to activate water Wa. This external base serves to polarize water Wa, either directly (in RAS-GAP ) or via an intercalating helping water molecule (Wh in Fig. 2a). This allows the enzymes to further lower the barrier for lysis of water Wa, and thus facilitate water attack onto the dissociated metaphosphate. In this way, the barrier for step 2 of the sequential reaction (ΔE 2 ǂ) can be lowered even more than can be achieved by only having partial positive charges interacting with the γ-phosphate group (described above).
During step 2 of the present sequential pathways in vacuum, the proton abstracted from water Wa is directly transferred onto the oxygen of the γ-phosphate. The corresponding transition state contains a 4-membered ring (Pγ–Oγ–Ha–Oa–Pγ), which induces some strain. In the enzymes, this transfer occurs via either a helping water (Wh) and/or the alcohol group of a nearby Serine side chain (for example Ser181 in myosin, see Fig. 2a) . The resulting 6- or 8-membered ring in the transition state allows for less strain, thereby further lowering the barrier ΔE 2 ǂ. Together with the activation from an external base, this explains how the enzymes manage to bring ΔE 2 ǂ down to values as low as 10–17 kcal mol−1, [21, 22, 30–32] while in vacuum the lowest value that could be achieved here for ΔE 2 ǂ is 21.9 kcal mol−1 (for αβγ triple protonation, Table 2).
In all combined quantum mechanical/classical (QM/MM) simulations of ATP hydrolysis in myosin during which a proton had first transferred to the γ-phosphate, the mechanism has always been found to be concurrent, never sequential [5, 33–37]. This is consistent with the results obtained here: Whenever the γ-phosphate is protonated, the Pγ-Oβγ bond is strengthened, preventing a sequential mechanism with prior breaking of the Pγ-Oβγ bond. Conversely, in all those calculations in which the γ-phosphate was not protonated, the mechanism has been observed to be sequential [7, 21, 38]. Similarly, in QM/MM simulations of the phosphoryl transfer reaction in bovine protein tyrosine phosphatase (BPTP), it was shown that the phosphoryl transfer occurs via a sequential mechanism with a 9 kcal mol−1 barrier when the leaving phosphate group is unprotonated [39, 40]. In contrast, when the leaving phosphate group was protonated, phosphoryl transfer was seen to occur via a concurrent mechanism with a barrier of 22 kcal mol−1 . This can be explained in the same terms as for the effect of γ-protonation on triphosphate hydrolysis: Protonation of the terminal phosphate strengthens the P–O bond, and the P–O bond cleavage become concurrent, thus resulting in a higher barrier.
A clear set of rules for the effects of α-, β- or γ- protonation on triphosphate hydrolysis in vacuum can be identified. They are: 1) Protonation of the α- or β-phosphate promotes Pγ–Oβγ bond cleavage, thus favoring a sequential reaction. 2) Protonation on γ favors a concurrent reaction, thus disfavoring the sequential pathway. 3) γ-protonation facilitates the attack of water onto the γ-phosphorus. These effects are somewhat additive, so that simultaneous protonation on the γ- and α- (or γ- and β-) positions can result in both concurrent and sequential reactions. These rules can be explained in terms of the charge distribution on the phosphates: i) α- and/or β-protonation pulls electrons towards the α,β-diphosphate moiety, favoring the charge distribution of the dissociated state (Fig. 2d). ii) γ-protonation has the opposite effect, pulling electrons towards the γ-phosphate, favoring the un-dissociated charge distribution (Fig. 2c), thereby making dissociation less favorable. iii) γ-protonation reduces the negative charge of the γ-phosphate, which thus becomes a better target for the nucleophilic attack by water Wa.
Breaking-up a water molecule is very difficult, and is the rate-limiting step in all pathways. Therefore, the sequential pathways tend to have a lower rate-limiting barrier than the concurrent reactions. One reason is that the energetic cost of breaking the Pγ–Oβγ bond (ΔE 1 ǂ) has already been paid in the previous step. The other reason is that the dissociated γ-phosphate (Fig. 2d) is planar and less negatively charged than the un-dissociated γ-phosphate (Fig. 2c), making the former a better target for the nucleophilic attack by water Wa. For this reason, the lowest energy barrier of hydrolysis is obtained for the α,β,γ-protonated case, which combines all effects.
The present calculations are consistent with experimental studies: Uncatalyzed phosphoryl transfer reaction from ATP, GTP and pyrophosphate are suggestive that the beta-gamma-bridging oxygen atom undergoes significant charge-increase (of −0.55 e) . Charge shift was also observed in the RAS catalyzed hydrolysis of GTP in GAP using time-resolved Fourier transform infrared difference spectroscopy . In NTPases, the charge shifts are induced by placing many positive partial charges in direct contact with each of the three phosphate groups. Additionally, the NTPases further lower the rate-limiting barrier of water lysis by placing a residue (such as Glu459 in myosin, Fig. 2a) nearby that acts as a better general base for water activation than the γ-phosphate. The present study helps to better understand the respective role of the many H-bond donors and positive charges in the active site of NTPases. Depending on its placement, each of these groups contributes differently to the catalytic mechanism, according to the set of rules listed above. It is known that ATP-γ-S is far more stable than ATP, and is not easily hydrolyzed by enzymes [44, 45]. An interesting computational study would be to compare the catalysis of ATP-γ-S with that of ATP.
In NTPase enzymes, the triphosphate moiety of NTP is complexed with a hexa-coordinated Mg2+ cation, therefore Mg2+(H2O)4–coordinated methyl triphosphate (shown in Fig. 1) was used here as substrate. Harmonic distance constraints between the oxygen and hydrogen atoms of magnesium coordinated water molecules were used to prevent undesired proton transfer from these waters to the triphosphate. In all cases studied here, water Wa is taken to transfer one of its protons to the nearest phosphate oxygen, namely of the γ-phosphate. This proton transfer mechanism is referred to as direct proton transfer [7, 46]. Reactant and product structures (see Fig. 1) were energy-optimized for each protonation case using the AM1/d semi-empirical method, with phosphorus parameters modified from those of York et. al. and magnesium parameters designed to be combinable with phosphorus, as previously described . The minimum energy paths (MEPs) and all first order saddle point between the reactant and product structures were computed with the Conjugate Peak Refinement (CPR) method, as implemented in the Trek module of CHARMM .
CPR finds the MEP by starting from an initial guess of the path, here the linear interpolation between the Cartesian coordinates of reactant and product. The path is treated as a chain of conformers, and this chain is gradually relaxed (by a controlled energy optimization of all the chain conformers) into a valley of the potential energy surface. By applying appropriate external constraints on the distance between the Pγ and the attacking (Oa) and leaving (Oβγ) oxygen atoms, the potential energy surface was initially shaped to make sure that the desired (either concurrent or a sequential) reaction valley is present for each case of protonation. The CPR search for a MEP was started with this “shaped” potential. Once the path-chain follows the desired valley (for example sequential), the shaping constraints are removed and the path optimization is continued with CPR. This procedure ensures that, when a valley for a given reaction type (for example concurrent) is present on the native (i.e. unshaped) energy surface, then this valley is found. Conversely, if the desired reaction type has no valley on the native potential, then after the shaping constraints are removed, CPR transforms the path-chain until it follows the actual (sequential in this example) reaction valley.
Given the large number of structures that are present along each MEP and that have to be energy-optimized (i.e., not only the transition states were optimized), it was helpful to use a semi-empirical QM method rather than (much slower) DFT methods. Starting from AM1/d parameters developed for phosphate/Mg2+ complexes, we further optimized the parameters of phosphorus for the computation of transition states of phosphate hydrolysis (listed in Table S2) . A comparison of the resulting energies for the hydrolysis reaction of dimethyl phosphate (complexed with Mg2+ and five water molecules) showed that the AM1/d method can reproduce the relative energy barriers obtained with DFT (B3LYP/6-31++G(d,p)), both for sequential as well as for concurrent [50, 51] mechanisms. Here, we also compared the reactant and the saddle point structures for the concurrent mechanism with fully deprotonated methyl-triphosphate obtained with the B3LYP/6-31 + G** method to those obtained with these optimized AM1/d parameters. They are shown in Additional file 1: Figure S1A and S1B and the corresponding activation barriers are given in Additional file 1: Table S1. The same comparison was done for the sequential mechanism with α-protonated triphosphate (Additional file 1: Figure S1C and S1D, Table S1). The resulting structures and the energy barriers are qualitatively similar, with an error for the activation barrier of less than 10 %, which shows that the present AM1/d method/parameters are adequate to study the effects of protonation on the barriers of triphosphate hydrolysis. Note that we found that the relative energy of the ADP/Pi products (i.e., after the crossing of all the barriers, at λ = 1 in Fig. 3) is not reliable with the AM1/d method, which tends to overstabilize the products compared to the reactant energy. It is possible that results of the completely or partly unprotonated triphosphate hydrolysis may alter when treated in solution. This is because these negatively charged triphosphate species would get more stable towards P-O bond cleavage in solutions.
ATP, adenosine triphopshate; MEP, minimum energy path; NTP, nucleoside triphsophate
Financial support by Deutsche Forschungsgemeinschaft (DFG) through Sonderforschungbericht-623 is gratefully acknowledged. Authors declare no conflict of interest.
Availability of data and materials
The datasets supporting the conclusions of this article are included within the article and its additional files.
SF designed the simulation setup, and contributed in editing the manuscript. FAK performed the calculations, and contributed in writing the manuscript. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Ethics approval and consent to participate
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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1 of or relating to or caused by magnetism; "magnetic forces"
2 having the properties of a magnet; i.e. of attracting iron or steel; "the hard disk is covered with a thin coat of magnetic material" [syn: magnetized, magnetised] [ant: antimagnetic]
3 capable of being magnetized [ant: nonmagnetic]
4 determined by earth's magnetic fields; "magnetic north"; "the needle of a magnetic compass points to the magnetic north pole" [ant: geographic]
5 having the properties of a magnet; the ability to draw or pull; "an attractive force"; "the knife hung on a magnetic board" [syn: attractive(a)] [ant: repulsive(a)]
6 possessing an extraordinary ability to attract; "a charismatic leader"; "a magnetic personality" [syn: charismatic]
- Rhymes: -ɛtɪk
of, relating to, caused by, or operating by magnetism
having the properties a magnet
determined by earth's magnetic fields
having an extraordinary ability to attract
- Finnish: magneettinen, puoleensavetävä
- French: magnétique m|f
- German: anziehend
- Greek: σαγηνευτικός
- Italian: magnetico , magnetica
- Japanese: 引きつける (hikitsukeru), 惹きつける (hikitsukeru)
- Portuguese: magnético , magnética
- Russian: магнетический (magnetíčeskij)
- Swedish: fängslande, förförisk, lockande, magnetisk, tilldragande
- Spanish: magnético
Translations to be checked
- ttbc Chinese: 磁性
- ttbc Korean: 자석
- ttbc Spanish: magnético m, magnética f
- ttbc Telugu: అయస్కాంత (ayaskaaMta)
In physics, magnetism is one of the phenomena by which materials exert attractive or repulsive forces on other materials. Some well-known materials that exhibit easily detectable magnetic properties (called magnets) are nickel, iron, cobalt, and their alloys; however, all materials are influenced to greater or lesser degree by the presence of a magnetic field.
Magnetism also has other manifestations in physics, particularly as one of the two components of electromagnetic waves such as light.
Aristotle attributes the first of what could be called a scientific discussion on magnetism to Thales, who lived from about 625 BC to about 545 BC. In China, the earliest literary reference to magnetism lies in a 4th century BC book called Book of the Devil Valley Master (鬼谷子): "The lodestone makes iron come or it attracts it." The earliest mention of the attraction of a needle appears in a work composed between 20 and 100 AD (Louen-heng): "A lodestone attracts a needle." The ancient Chinese scientist Shen Kuo (1031-1095) was the first person to write of the magnetic needle compass and that it improved the accuracy of navigation by employing the astronomical concept of true north (Dream Pool Essays, 1088 AD), and by the 12th century the Chinese were known to use the lodestone compass for navigation. Alexander Neckham, by 1187, was the first in Europe to describe the compass and its use for navigation. In 1269 Peter Peregrinus de Maricourt wrote the Epistola de magnete, the first extant treatise describing the properties of magnets.
In 1600 William Gilbert published his De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure (On the Magnet and Magnetic Bodies, and on the Great Magnet the Earth). In this work he describes many of his experiments with his model earth called the terrella. From his experiments, he concluded that the Earth was itself magnetic and that this was the reason compasses pointed north (previously, some believed that it was the pole star (Polaris) or a large magnetic island on the north pole that attracted the compass).
An understanding of the relationship between electricity and magnetism began in 1819 with work by Hans Christian Oersted, a professor at the University of Copenhagen, who discovered more or less by accident that an electric current could influence a compass needle. This landmark experiment is known as Oersted's Experiment. Several other experiments followed, with André-Marie Ampère, Carl Friedrich Gauss, Michael Faraday, and others finding further links between magnetism and electricity. James Clerk Maxwell synthesized and expanded these insights into Maxwell's equations, unifying electricity, magnetism, and optics into the field of electromagnetism. In 1905, Einstein used these laws in motivating his theory of special relativity, requiring that the laws held true in all inertial reference frames.
Electromagnetism has continued to develop into the twentieth century, being incorporated into the more fundamental theories of gauge theory, quantum electrodynamics, electroweak theory, and finally the standard model.
Physics of magnetism
Magnets and magnetic materialsEvery electron, by its nature, is a small magnet (see Electron magnetic dipole moment). Ordinarily, the countless electrons in a material are randomly oriented in different directions, leaving no effect on average, but in a bar magnet the electrons are aligned in the same direction, so they act cooperatively, creating a net magnetic field.
In addition to the electron's intrinsic magnetic field, there is sometimes an additional magnetic field that results from the electron's orbital motion about the nucleus. This effect is analogous to how a current-carrying loop of wire generates a magnetic field (see Magnetic dipole). Again, ordinarily, the motion of the electrons is such that there is no average field from the material, but in certain conditions, the motion can line up so as to produce a measurable total field.
The overall magnetic behavior of a material can vary widely, depending on the structure of the material, and particularly on its electron configuration. Several forms of magnetic behavior have been observed in different materials, including:
Magnetism, electricity, and special relativityAs a consequence of Einstein's theory of special relativity, electricity and magnetism are understood to be fundamentally interlinked. Both magnetism lacking electricity, and electricity without magnetism, are inconsistent with special relativity, due to such effects as length contraction, time dilation, and the fact that the magnetic force is velocity-dependent. However, when both electricity and magnetism are taken into account, the resulting theory (electromagnetism) is fully consistent with special relativity. In particular, a phenomenon that appears purely electric to one observer may be purely magnetic to another, or more generally the relative contributions of electricity and magnetism are dependent on the frame of reference. Thus, special relativity "mixes" electricity and magnetism into a single, inseparable phenomenon called electromagnetism (analogously to how special relativity "mixes" space and time into spacetime).
Magnetic fields and forces
The phenomenon of magnetism is "mediated" by the magnetic field -- i.e., an electric current or magnetic dipole creates a magnetic field, and that field, in turn, imparts magnetic forces on other particles that are in the fields.
To an excellent approximation (but ignoring some quantum effects---see quantum electrodynamics), Maxwell's equations (which simplify to the Biot-Savart law in the case of steady currents) describe the origin and behavior of the fields that govern these forces. Therefore magnetism is seen whenever electrically charged particles are in motion---for example, from movement of electrons in an electric current, or in certain cases from the orbital motion of electrons around an atom's nucleus. They also arise from "intrinsic" magnetic dipoles arising from quantum effects, i.e. from quantum-mechanical spin.
The same situations which create magnetic fields (charge moving in a current or in an atom, and intrinsic magnetic dipoles) are also the situations in which a magnetic field has an effect, creating a force. Following is the formula for moving charge; for the forces on an intrinsic dipole, see magnetic dipole.
When a charged particle moves through a magnetic field B, it feels a force F given by the cross product:
- \vec = q \vec \times \vec
- F = q v B \sin\theta\,
One tool for determining the direction of the velocity vector of a moving charge, the magnetic field, and the force exerted is labeling the index finger "V", the middle finger "B", and the thumb "F" with your right hand. When making a gun-like configuration (with the middle finger crossing under the index finger), the fingers represent the velocity vector, magnetic field vector, and force vector, respectively. See also right hand rule.
Lenz's law gives the direction of the induced electromotive force (emf) and current resulting from electromagnetic induction. German physicist Heinrich Lenz formulated it in 1834.
A very common source of magnetic field shown in nature is a dipole, with a "South pole" and a "North pole"; terms dating back to the use of magnets as compasses, interacting with the Earth's magnetic field to indicate North and South on the globe. Since opposite ends of magnets are attracted, the north pole of a magnet is attracted to the south pole of another magnet. Interestingly, this concept of opposite polaraties attracting wasn't used in the naming convention for the earth's magnetic field, so the earth's magnetic north pole (in Canada) attracts the magnetic north pole of a compass see North Magnetic Pole.
A magnetic field contains energy, and physical systems move toward configurations with lower energy. Therefore, when placed in a magnetic field, a magnetic dipole tends to align itself in opposed polarity to that field, thereby canceling the net field strength as much as possible and lowering the energy stored in that field to a minimum. For instance, two identical bar magnets placed side-to-side normally line up North to South, resulting in a much smaller net magnetic field, and resist any attempts to reorient them to point in the same direction. The energy required to reorient them in that configuration is then stored in the resulting magnetic field, which is double the strength of the field of each individual magnet. (This is, of course, why a magnet used as a compass interacts with the Earth's magnetic field to indicate North and South).
An alternative, equivalent formulation, which is often easier to apply but perhaps offers less insight, is that a magnetic dipole in a magnetic field experiences a torque and a force which can be expressed in terms of the field and the strength of the dipole (i.e., its magnetic dipole moment). For these equations, see magnetic dipole.
Magnetic monopolesSince a bar magnet gets its ferromagnetism from electrons distributed evenly throughout the bar, when a bar magnet is cut in half, each of the resulting pieces is a smaller bar magnet. Even though a magnet is said to have a north pole and a south pole, these two poles cannot be separated from each other. A monopole — if such a thing exists — would be a new and fundamentally different kind of magnetic object. It would act as an isolated north pole, not attached to a south pole, or vice versa. Monopoles would carry "magnetic charge" analogous to electric charge. Despite systematic searches since 1931, as of 2006, they have never been observed, and could very well not exist.
Nevertheless, some theoretical physics models predict the existence of these magnetic monopoles. Paul Dirac observed in 1931 that, because electricity and magnetism show a certain symmetry, just as quantum theory predicts that individual positive or negative electric charges can be observed without the opposing charge, isolated South or North magnetic poles should be observable. Using quantum theory Dirac showed that if magnetic monopoles exist, then one could explain the quantization of electric charge---that is, why the observed elementary particles carry charges that are multiples of the charge of the electron.
Certain grand unified theories predict the existence of monopoles which, unlike elementary particles, are solitons (localized energy packets). The initial results of using these models to estimate the number of monopoles created in the big bang contradicted cosmological observations — the monopoles would have been so plentiful and massive that they would have long since halted the expansion of the universe. However, the idea of inflation (for which this problem served as a partial motivation) was successful in solving this problem, creating models in which monopoles existed but were rare enough to be consistent with current observations.
Units of electromagnetism
SI units related to magnetism
- Earth's magnetic field
- Lenz's law
- Plastic magnet
- Magnetic field
- Magnetic bearing
- Magnetic cooling
- Magnet therapy
- Magnetic circuit
- Magnetic moment
- Magnetic structure
- Magnetic susceptibility
- Michael Faraday
- James Clerk Maxwell
- Neodymium magnet
- Rare-earth magnet
- Spin wave
- Spontaneous magnetization
- Magnetic stirrer
- Permanent Magnet and Electromechanical Devices: Materials, Analysis and Applications
- Introduction to Electrodynamics (3rd ed.)
- Handbook of Magnetism and Advanced Magnetic Materials, 5 Volume Set
- Physics for Scientists and Engineers: Electricity, Magnetism, Light, and Elementary Modern Physics (5th ed.)
magnetic in Afrikaans: Magnetisme
magnetic in Arabic: مغناطيسية
magnetic in Azerbaijani: Maqnitizm
magnetic in Bosnian: Magnetizam
magnetic in Breton: Gwarellegezh
magnetic in Bulgarian: Магнетизъм
magnetic in Catalan: Magnetisme
magnetic in Czech: Magnetismus
magnetic in Danish: Magnetisme
magnetic in German: Magnetismus
magnetic in Modern Greek (1453-): Μαγνητισμός
magnetic in Spanish: Magnetismo
magnetic in Esperanto: Magnetismo
magnetic in French: Magnétisme
magnetic in Galician: Magnetismo
magnetic in Korean: 자기
magnetic in Croatian: Magnetizam
magnetic in Indonesian: Magnetisme
magnetic in Italian: Magnetismo
magnetic in Hebrew: מגנטיות
magnetic in Luxembourgish: Magnetismus
magnetic in Lithuanian: Magnetizmas
magnetic in Lojban: makykai
magnetic in Hungarian: Mágnesség
magnetic in Malayalam: കാന്തികത
magnetic in Dutch: Magnetisme
magnetic in Japanese: 磁性
magnetic in Norwegian: Magnetisme
magnetic in Norwegian Nynorsk: Magnetisme
magnetic in Polish: Magnetyzm
magnetic in Portuguese: Magnetismo
magnetic in Romanian: Magnetism
magnetic in Quechua: Llut'ariy
magnetic in Russian: Магнетизм
magnetic in Simple English: Magnetism
magnetic in Slovak: Magnetizmus
magnetic in Slovenian: Magnetizem
magnetic in Serbian: Магнетизам
magnetic in Finnish: Magnetismi
magnetic in Swedish: Magnetism
magnetic in Thai: ความเป็นแม่เหล็ก
magnetic in Vietnamese: Từ học
magnetic in Turkish: Mıknatıslık
magnetic in Ukrainian: Магнетизм
magnetic in Urdu: مقناطیسیت
magnetic in Chinese: 磁
absorbing, adductive, alluring, appealing, arresting, attracting, attractive, attrahent, authoritative, beguiling, bewitching, captivating, charismatic, charming, consequential, consuming, diamagnetic, dragging, drawing, effective, effectual, efficacious, electromagnetic, enchanting, engaging, engrossing, enthralling, entrancing, estimable, fascinating, ferromagnetic, gripping, holding, hypnotic, important, influential, inviting, irresistible, magnetized, mesmeric, mesmerizing, momentous, obsessing, obsessive, personable, persuasive, polar, potent, powerful, prestigious, pulling, reputable, seductive, spellbinding, strong, suasive, substantial, sympathetic, telling, tugging, weighty, winning, winsome | <urn:uuid:71eab4d9-9591-4d98-8272-74c5bd6688ab> | 3.546875 | 3,616 | Knowledge Article | Science & Tech. | 11.009579 | 95,585,376 |
Nature-inspired synthetic membranes could aid water purification, energy, and healthcare needs
Materials scientists have created a new material that performs like a cell membrane found in nature. Such a material has long been sought for applications as varied as water purification and drug delivery.
This simulated cross-section shows how the lipid-like peptoids interact to form a membrane. Each peptoid has two sections: a fatty-like region that interacts via benzene rings (shown in pink) with its neighbors to form a sheet. And a water-loving region that juts above or below the flat sheet. Each region can be designed to have specific functions.
Credit: Chun-Long Chen/PNNL
Referred to as a lipid-like peptoid (we'll unpack that in a second), the material can assemble itself into a sheet thinner, but more stable, than a soap bubble, the researchers report July 12 in Nature Communications. The assembled sheet can withstand being submerged in a variety of liquids and can even repair itself after damage.
"Nature is very smart. Researchers are trying to make biomimetic membranes that are stable and have certain desired properties of cell membranes," said chemist Chun-Long Chen at the Department of Energy's Pacific Northwest National Laboratory. "We believe these materials have potential in water filters, sensors, drug delivery and especially fuel cells or other energy applications."
The amazing membrane
Cell membranes are amazing materials. Made from thin sheets of fatty molecules called lipids, they are at least ten times thinner than an iridescent soap bubble and yet allow cells to collectively form organisms as diverse at bacteria, trees and people.
Cell membranes are very selective about what they let pass through, using tiny embedded proteins as gatekeepers. Membranes repair dings to their structure automatically and change thickness to pass signals from the outside environment to the cell's interior, where most of the action is.
Scientists would like to take advantage of membrane properties such as gatekeeping to make filters or signaling to make sensors. A cell-membrane-like material would have advantages over other thin materials such as graphene. For example, mimicking a cell membrane's efficient gatekeeping could result in water purifying membranes that don't require a lot of pressure or energy to push the water through.
Synthetic molecules called peptoids have caught the interest of researchers because they are cheap, versatile and customizable. They are like natural proteins, including those that embed themselves in cell membranes, and can be designed to have very specific forms and functions. So Chen and colleagues decided to see if they could design peptoids to make them more lipid-like.
Lipid molecules are long and mostly straight: They have a fatty end that prefers to hang out with other fats, and a water-like end that prefers the comfort of water. Because of this chemistry, lipid molecules arrange themselves with the fatty ends pointed toward each other, sandwiched between the water-loving ends pointed out. Scientists call this a lipid bilayer, essentially a sheet that envelops the contents of a cell. Proteins or carbohydrate molecules embed themselves in the membranous sheet.
Inspired by this, Chen and colleagues designed peptoids in which each base peptoid was a long molecule with one end water-loving and the other end fat-loving. They chose chemical features that they hoped would encourage the individual molecules to pack together. They examined the resulting structures using a variety of analysis methods, including some at the Advanced Light Source and the Molecular Foundry, two DOE Office of Science User Facilities at Lawrence Berkeley National Laboratory.
The team found that after putting the lipid-like peptoids into a liquid solution, the molecules spontaneously crystallized and formed what the scientists call nanomembranes -- straight-edged sheets as thin as cell membranes -- floating in the beaker. These nanomembranes maintained their structure in water or alcohol, at different temperatures, in solutions with high or low pH, or high concentrations of salts, a feat that few cell membranes could accomplish.
A view from the middle
To better understand the nanomembranes, the team simulated how single peptoid molecules interacted with each other using molecular dynamics software. The simulated peptoids formed a membrane reminiscent of a lipid bilayer: The fat-loving ends lined up in the middle, and their water-loving ends pointed outward either above or below.
To test whether their synthetic membranes had the signaling ability of cell membranes, the researchers added a touch of sodium chloride salt. Salt is involved in the last step in many signaling sequences and causes real cell membranes to thicken up. And thicken up the peptoids did. The more salt the researchers added, the thicker the nanomembranes became, reaching about 125 percent of their original thickness in the range of salt concentrations they tested.
Real membranes also hold proteins that have specific functions, such as ones that let water, and only water, through. Chen's group tested the ability of peptoids to do so by introducing a variety of side chains. Side chains are essentially small molecules of different shapes, sizes and chemical natures attached to the longer lipid-like peptoids. They tried 10 different designs. In each case, the peptoids assembled into the nanomembranes with the core structure remaining intact. The team could also build a carbohydrate into nanomembranes, showing the material can be designed to have versatile functions.
The team then tested the nanomembranes to see if they could repair themselves, a useful feature for membranes that could get scratched during use. After cutting slits in a membrane, they added more of the lipid-like peptoid. Viewed under a microscope over the course of a few hours, the scratches filled up with more peptoid and the nanomembrane became complete again. (Compare this to cuts in paper, which don't spontaneously repair themselves even after being taped up.)
Taken together, the results showed the researchers that they are on the right path to making synthetic cell membrane-like materials. However, there are still some challenges to be addressed for applications. For example, the researchers would like to better understand how the membranes form so they can make many desirable sizes.
The next step, Chen said, is to build biomimetic membranes by incorporating natural membrane proteins or other synthetic water channels such as carbon nanotubes into these sheet matrices. The team is also looking into ways to make the peptoid membranes conductive for energy uses.
This work was supported by the Department of Energy Office of Science and PNNL.
Reference: Haibao Jin, Fang Jiao, Michael D. Daily, Yulin Chen, Feng Yan, Yan-Huai Ding, Xin Zhang, Ellen J. Robertson, Marcel D. Baer & Chun-Long Chen. Highly stable and self-repairing membrane-mimetic 2D nanomaterials assembled from lipid-like peptoids, Nature Communications, July 12, 2016, doi: 10.1038/ncomms12252.
Interdisciplinary teams at Pacific Northwest National Laboratory address many of America's most pressing issues in energy, the environment and national security through advances in basic and applied science. Founded in 1965, PNNL employs 4,400 staff and has an annual budget of nearly $1 billion. It is managed by Battelle for the U.S. Department of Energy's Office of Science. As the single largest supporter of basic research in the physical sciences in the United States, the Office of Science is working to address some of the most pressing challenges of our time. For more information on PNNL, visit the PNNL News Center, or follow PNNL on Facebook, Google+, LinkedIn and Twitter.
Mary Beckman | EurekAlert!
In borophene, boundaries are no barrier
17.07.2018 | Rice University
Research finds new molecular structures in boron-based nanoclusters
13.07.2018 | Brown University
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
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Has Typeclasses and RankNTypes
Ranked in these QuestionsQuestion Ranking
Pro Great async language support
Dart is a single threaded programming language. So if any piece of code blocks the execution of the program, the program practically freezes. To avoid this Dart makes use of asynchronous operations which let your program run without getting blocked. This is done through Future objects.
A Future is an object which represent a means for getting a value at a certain point in the future. A function may invoke a Future and when that happens, two outcomes can be achieved:
- The function is unable to return a value, so it queues up work to be done and returns an uncompleted Future object.
- Or later when a value is available to be returned, the Future object completes with that value.
Pro Great standard library
Dart includes a truly comprehensive core library, making it unnecessary to include disparate, external resources for basic functionalities Other than reducing the need to pull in various 3rd-party utilities this also ensures that all Dart code looks and feels the same.
Out of the box, the developer gets core libraries to help with: async, collections, strings, regexps, conversions, formats, file I/O, math, typed data, and more.
Pro A lot of tools are available to help in developing with Dart
Dart has a lot of tools available which help with developing Dart applications. Some examples of those tools include:
- pub - package and dependency management and build tool
- analyzer - static syntax analysis with linter, quick fixes, autocompletion support for easy IDE integration
- test - powerful and flexible testing framework and test runner
- dev_compiler - generate reusable JS instead of tree-shaken minified JS output (work in progress)
- dartfmt_ - source code formatter
- server-side VM
- observatory - a powerful tool for profiling and debugging running Dart code (for Dartium and Dart server code)
Pro No compile time in development
Dartium (Chromium derivative) is a browser with integrated Dart VM, which allows you to run and debug native Dart code during development for short edit-reload cycles. Only for testing on other browsers and deployment is transpiling to JS necessary.
In Dart many browser differences (subtle differences and also missing features) are abstracted away or polyfilled. When Dart is transpiled to JS the output works on all supported browsers. There is usually no need to load polyfills or to consider browser differences during development. No need for libraries like jQuery to make the same code work the same on all browsers.
Pro Will be familiar to Java developers
The language will look familiar to Java developers, easing the learning curve.
And yet, while it's similar, it has some nice syntax facilities to avoid common boilerplate code found in Java. Code is terser, yet readable.
Pro Easy prototyping
Dart has an optional type system which makes Dart a great language for prototyping. It encourages developers to gradually evolve their programs without worrying about types first.
Pro Can compile to efficient machine code
Dart was designed to be as expressive as possible. Ahead-of-time compilers can compile Dart code to efficient machine code. This is especially important when deploying to mobile where you don't want (or can't) use a JIT.
Pro Optional strong mode.
Strong mode applies a more restrictive type system to Dart to address its unsound, surprising behavior in certain cases.
Pro AngularDart 2.0 support
Pro Support of semi-coroutines (generators)
Generators, also known as semicoroutines, are also a generalization of subroutines.
Generators are primarily used to simplify the control of iteration behavior of a loop, the
yield statement in a generator passes a value back to a parent routine.
A generator is very similar to a function that returns an array, in that a generator has a certain number of values. But instead of building and returning an array that contains all the wanted values, a generator returns them one at a time, this saves memory and allows the caller function to start processing the first few values immediately.
Pro Higher kinded types
Has Typeclasses and RankNTypes
Pro Modules can be compiled to CommonJS
Pro High performance FFI code
Pro Has row polymorphism and extensible effects
Pro Type safety
Compiling should be your first unit test. A tight type system (static and hopefully strong) will catch many logic errors that are often difficult to spot through debugging. In languages like PureScript, if it compiles, it often runs properly.
FFI system is quite good and easy to use. You can import functions curried or not curried. Records and arrays use native JS objects and arrays.
Pro Pure functional language
You cannot have side effects, unless a function is explicitly defined as so.
Pro Awesome web frameworks
Halogen (VDOM, similar to ELM)
And hit these up with Signals, Isolated/(Managed?) Components, powerful functions and FFI
Con Dart SDK does not provide standard (out of the box) way to access SQL-based databases on server side
This missing (but very popular) feature requires to use 3rd-party packages developed by the personal enthusiasts or very small groups of enthusiasts, which is not very convenient because they are all very fragmented in terms of content, the essence and capabilities.
Con Small community, little momentum
Con Lots of dependencies needed to get started
Purescript is written in Haskell, but meant to be used with Node.js. As a result, to get started , users must install ghc, cabal, node.js, grunt, and bower. Purescript also has its own compiler, and different semantics form Haskell, and so even after installing, there's still some overhead to getting productive with Purescript.
Con Lack of good IDE/tooling support
Con Restrictive FFI
Con Slow compilation
On large project, for example Halogen | <urn:uuid:b7ee5a88-1e19-437e-b02f-c9b20c47ae34> | 2.59375 | 1,254 | Documentation | Software Dev. | 33.353752 | 95,585,393 |
Scientists at The Scripps Research Institute and the Salk Institute for Biological Studies are reporting a possible answer to a longstanding question in research on the origins of life on Earth--how did the first amino acids form the first peptides?
Peptides and proteins are strings of amino acid building blocks, and they are one of the most important classes of biological molecules found in living things today. Fifty years of chemical research on the origins of life has shown that amino acids could have formed spontaneously on the early Earth environment or could have been introduced onto the early Earth from meteorites.
"There are lots of ways to make amino acids," says Professor M. Reza Ghadiri, Ph.D., who is a member of The Skaggs Institute for Chemical Biology at Scripps Research. "But the question is, how do you couple them together?"
Ghadiri and Luke Leman, who is a member of the Kellogg School of Science and Technology at Scripps Research, worked out one possible solution with Leslie Orgel of the Salk Institute. In the latest issue of the journal Science, Leman, Ghadiri, and Orgel suggest that the missing link is a chemical component of volcanic gas known as carbonyl sulfide.
Jason Bardi | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:0809c026-138b-4414-861b-c3add0856d90> | 3.390625 | 846 | Content Listing | Science & Tech. | 39.90162 | 95,585,419 |
Scientists have spent more than $ 22 million in search of a new underwater volcano, about which there was speculation. It is reported that on the coast of New Zealand discovered a giant volcano, called Kiwi.
Scientist Cornel de Ronde, who was involved in the testing of submarines, together with colleagues on the coast of New Zealand found an underwater volcano. It is reported that the magma and volcanic rocks, the Kiwi is extremely rich in metals such as copper and gold. The main objective of the next expedition to the hydrologically active submarine volcano in the world was to learn more about how metals are formed by underwater volcanoes.
Scientists also got a better understanding of what regulates the chemical composition of sea water. As it turned out, the chemical reactions between rocks and seawater at the depth of the volcano change the chemistry of the fluid that is released into the ocean through hydrothermal vents, ” said Dr. Suzane Humphries from the American Oceanographic Institute woods hole. | <urn:uuid:1b618865-3ab1-4bcf-be97-adaa36f20d3c> | 3.515625 | 201 | News Article | Science & Tech. | 36.203761 | 95,585,460 |
More potential evidence that we may not be alone in the universe. Kepler telescope discovered 715 new planets beyond our solar system. So far, NASA has identified four of these planets as orbiting a hospital zone where water can keep a liquid state, according to the BBC.
According to this video from NASA, this find doubled the number of known planets. Doubled. We have now identified 1,700 planets outside of our solar system. "The more we explore, the more we find familiar traces of ourselves among the stars that remind us of home," says Jason Rowe of the SETI Institute in Mountain View, California, and co-leader of the research team.
This tremendous discovery obviously has some exciting implications. For one thing, as Stephen Hawking pointed out, as reported on Big Think, we need to start looking for another Earth and colonizing space if our species wants to survive. Kepler is essentially acting as our real-estate agent. What's as exciting is that more finds like this one could lead us to our nearest sophisticated neighbors. Believe whatever you want about the existence of aliens, hauls like this one indicate that there's just so much we don't know about space, and so much possibility for life beyond Earth.
What do you think this latest discovery means for humankind? Tell us in the comments section. The BBC has more on Kepler's planetary goldmine. | <urn:uuid:1d791b8f-efc3-4fc7-9199-4ba3b49b30dc> | 2.890625 | 277 | News Article | Science & Tech. | 50.868886 | 95,585,472 |
Researchers study cheese to unlock secrets of how microbial communities form
Go ahead and call Rachel Dutton's research cheesy if you must. As far as she's concerned, it's anything but an insult.
A Bauer Fellow at the Faculty of Arts and Sciences' Center for Systems Biology, Dutton and her lab study cheese – or more precisely – the bacteria and fungi that live on cheese, in an effort to better understand how microbial communities form.
After studying 137 varieties of cheese collected in 10 different countries, Dutton has been able to identify three general types of microbial communities that live on cheese, opening the door to using each as a "model" community for the study of whether and how various microbes and fungi compete or cooperate as they form communities, what molecules may be involved in the process and what mechanisms may be involved. The study is described in a July 17 paper in Cell.
"We often use model organisms like E. coli or C. elegans because they can give us an understanding of the basic mechanisms and principles of how biology works," Dutton said. "The goal of this work was to identify something like a model organism, but for microbial communities – something we can bring into the lab and easily replicate and manipulate.
"The challenge in studying these communities is that many of the environments where they are found, such as the human body or the soil, are hard to replicate because they're so complicated," she continued. "Cheese seemed to offer a system…in which we knew exactly what these communities were growing on, so we thought we should be able to replicate that environment in the lab."
To understand what a model community might look like, Dutton and her lab first set out to identify dozens of naturally-occurring communities by collecting samples from the rinds of dozens of varieties of cheese around the world.
"We did some travelling in Europe and worked directly with a number of cheese-makers by having them send us samples or vising to collect samples, and in some cases we were able to collect samples from places like Formaggio Kitchen and other cheese shops," she said.
By sequencing those samples, Dutton was able to identify the type of bacteria and fungi in each, and found that while there was wide variation among different samples, the samples could be separated into one of three main types of communities.
"What we ended up finding is there are microbes which occur in all the areas where cheese is made," she said. "What was interesting is if you make the same type of cheese in France or in Vermont, they will have very similar communities. What seems to be driving the type of community you find is the environment that the cheese-maker creates on the surface of the cheese, so you can make two cheeses that are very similar in two different places, or you can make two very different cheeses in the same place."
Working in the lab, Dutton and colleagues were able to isolate each species of microbe and fungi found in the samples and conduct tests aimed at reproducing the communities found on different cheeses. "In many environments, it is challenging to isolate all of the microbes, so we were surprised to find that we could culture all of the species present on cheese rinds. This gives us a great foundation for being able to study communities in the lab," says Julie Button, a postdoctoral researcher in the Dutton lab.
"If we know a particular cheese has certain species, we can mix them together and try to recreate that community in the lab," Dutton said. "For example, we might try to simply put those species together at the same time in equal amounts to see if the community that forms is similar to that found in the sample."
The study was also aimed at understanding how various species of bacteria and fungi interact, and identified several instances in which certain bacteria halted fungal growth, and vice versa.
"We are now working with chemists to characterize what the molecules are that different bacteria might use to kill a fungus," Dutton said. "It's also possible that there may be anti-microbials that may arise from this that are normally at play during the formation of a community."
While wider applications for understanding how bacterial communities form may eventually emerge, Dutton said there are still a number of fundamental questions to answer in the short term.
"There are so many wide open questions in thinking about how microbial communities work, that future research could go in a number of different directions," she said. "Our goal is to understand some of these fundamental questions, such as: Are there certain principles that are operating as a community forms, and can we control those factors in the lab?
"Cheese is fascinating to me in its own right – it's somewhat surprising that, for a food that we've been eating for thousands of years, we don't have a complete understanding of the microorganisms that are present in this food."
But now that Dutton has that understanding, does she still eat cheese?
"I do," she said with a laugh. "But I'm very picky, because I like very good cheese now."
Peter Reuell | Eurek Alert!
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Life Sciences
17.07.2018 | Information Technology
17.07.2018 | Power and Electrical Engineering | <urn:uuid:0665c4dc-cef7-42cb-8159-a7ad9a793002> | 3.703125 | 1,717 | Content Listing | Science & Tech. | 42.904436 | 95,585,479 |
On our Friday the 13th full moon last week, I suspected the myth about more lunacy occurring at full moon was certainly making the rounds. There is also the notion that there are more births at full moon than at other times.
I actually used to include mention of the birth myth in my astronomy class until I asked myself one day, “How do I know that?”
I decided to investigate. A couple of small studies had been done. but nothing with a really large data set. I contacted Joyce Martin at the National Center for Health Statistics and described what I wanted to study. When she stopped laughing, she agreed to provide the data on 50 million live births spanning a decade.
The data were supplied in printed tables of the number of births on each date for 10 years. I had a student research assistant enter all of the numbers into computer data files; we then developed programs that would sort the data into bins for each day of the lunar phase cycle.
The result? No statistically significant peak in the birthrate occurs at full moon or at any other particular phase, just random variations about the average.
A common but incorrect explanation for the purported but absent peak is the gravitational effect of the moon. After all, we need a physical connection, and gravitation (think of tides) is all that we have.
But if a gravitational effect existed, it would not depend on the phase of the moon but the variation in the distance to the moon. The moon’s distance varies about 10 percent during its elliptical orbit around Earth, and this variation is not tied to the phases: It is not closest every full moon, for example.
Therefore, we plotted the birthrate vs. the distance to the moon and, again, we saw no dependence in the results. But, we would not expect one anyway, since the gravitational force of the moon on a person is too small to have any biophysical effect.
So, why does the full-moon birth myth live on? Probably for the simple reason that you remember what you see and not what you don’t. The most likely moon to be seen up in the air at night is the full moon – it rises at sunset and sets at sunrise. The delivery nurse, changing shifts or taking a break outside during a hectic night, is most likely to see and remember a full moon. All the other nights will not be remembered.
The myth will outlive me and my science. Anecdotal evidence will trump my analysis. Still, believing a myth will not make it true.
Daniel B. Caton is a physics and astronomy professor and director of observatories at Appalachian State University. Email: firstname.lastname@example.org. More on this month’s column: www.upintheair.info. | <urn:uuid:f305bd75-0d66-45cc-aeaf-08ef174d0c5b> | 3.234375 | 575 | Nonfiction Writing | Science & Tech. | 59.124842 | 95,585,491 |
In snakes, venom composition varies both between species and within a particular species. Land snakes feed on a range of animals and birds, so scientists think that these snakes need a diverse array of toxins in their venom. Sea snakes, on the other hand, tend to have a more restricted diet, feeding only on fish. The toxins in these snakes have now been shown to be less diverse than those in terrestrial snakes.
Professor R Manjunatha Kini and colleagues from the National University of Singapore examined two kinds of sea snakes. They constructed complementary DNA libraries from the venom glands of the reptiles, representing only the stretches of DNA that code for venom gland proteins, and studied two types of protein toxins. The three-finger toxins (3FTx) and the phospholipase A2 (PLA2) enzymes are the main components of sea snake venom.
Although the sea snakes studied lived in very different aquatic environments, the toxins examined were similar in both and the genes encoding the toxins were highly conserved. By contrast, the same toxins in land snakes and sea kraits (which fall between land and sea snakes) showed much greater diversity. The researchers suggest that the toxin genes in sea snakes have remained relatively unchanged because of sea snakes share the same kind of feeding behaviour and diet.
"We examine toxin genes of snakes to identify new toxins, some of which will be useful in developing new therapeutic strategies to treat human diseases," says Prof Kini from the Department of Biological Sciences, National University of Singapore. "A new anticoagulant or a hypotensive toxin may help us develop new cardiovascular drugs to block unwanted clot formation or to lower the blood pressure."
Charlotte Webber | alfa
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Materials Sciences
19.07.2018 | Earth Sciences
19.07.2018 | Life Sciences | <urn:uuid:e2cd36ff-d4e1-474d-9848-238ed767b151> | 3.515625 | 981 | Content Listing | Science & Tech. | 39.541857 | 95,585,509 |
The strength of the gravitational attraction between two objects represents the amount of gravitational energy in the field which attracts them towards each other. When they are infinitely far apart, the gravitational attraction and hence energy approach zero. As two such massive objects move towards each other, the motion accelerates under gravity causing an increase in the positive kinetic energy of the system. At the same time, the gravitational attraction - and hence energy - also increase in magnitude, but the law of energy conservation requires that the net energy of the system not change. This issue can only be resolved if the change in gravitational energy is negative, thus cancelling out the positive change in kinetic energy. Since the gravitational energy is getting stronger, this decrease can only mean that it is negative.
A universe in which positive energy dominates will eventually collapse in a "big crunch", while an "open" universe in which negative energy dominates will either expand indefinitely or eventually disintegrate in a "big rip". In the zero-energy universe model ("flat" or "Euclidean"), the total amount of energy in the universe is exactly zero: its amount of positive energy in the form of matter is exactly cancelled out by its negative energy in the form of gravity.
Quantum field effects
In the Casimir effect, two flat plates placed very close together restrict the wavelengths of quanta which can exist between them. This in turn restricts the types and hence number and density of virtual particle pairs which can form in the intervening vacuum and can result in a negative energy density. This causes an attractive force between the plates, which has been measured.
It is possible to arrange multiple beams of laser light such that destructive quantum interference suppresses the vacuum fluctuations. Such a squeezed vacuum state involves negative energy. The repetitive waveform of light leads to alternating regions of positive and negative energy.
According to the theory of the Dirac sea, developed by Paul Dirac in 1930, the vacuum of space is full of negative energy. This theory was developed to explain the anomaly of negative-energy quantum states predicted by the Dirac equation.
The Dirac sea theory correctly predicted the existence of antimatter two years prior to the discovery of the positron in 1932 by Carl Anderson. However, the Dirac sea theory treats antimatter as a hole where there is the absence of a particle rather than as a real particle. Quantum field theory (QFT), developed in the 1930s, deals with antimatter in a way that treats antimatter as made of real particles rather than the absence of particles, and treats a vacuum as being empty of particles rather than full of negative-energy particles like in the Dirac sea theory.
Quantum field theory has displaced the Dirac sea theory as a more popular explanation of these aspects of physics. Both the Dirac sea theory and quantum field theory are equivalent by means of a Bogoliubov transformation, so the Dirac sea can be viewed as an alternative formulation of quantum field theory, and is thus consistent with it.
Negative energy appears in the speculative theory of wormholes, where it is needed to keep the wormhole open. A wormhole directly connects two locations which may be separated arbitrarily far apart in both space and time, and in principle allows near-instantaneous travel between them.
A theoretical principle for a faster-than-light (FTL) warp drive for spaceships has been suggested, involving negative energy. The Alcubierre drive comprises a solution to Einstein's equations of general relativity, in which a bubble of spacetime is moved rapidly by expanding space behind it and shrinking space in front of it.
- Alan Guth The Inflationary Universe: The Quest for a New Theory of Cosmic Origins (1997), Random House, ISBN 0-224-04448-6 Appendix A: Gravitational Energy demonstrates the negativity of gravitational energy.
- Stephen Hawking; The Grand Design, 2010, Page 180.
- Everett, Allen; Roman, Thomas (2012). Time Travel and Warp Drives. University of Chicago Press. p. 167. ISBN 0-226-22498-8.
- Ford and Roman 2000
- Stephen Hawking; A Brief History of Time, Bantam 1988, Pages 105-107. ISBN 0-593-01518-5
- López de Recalde, Andrea (2017). The Standard Electro-Weak Theory, 2nd Edition. Morrisville, North Carolina: LuLu Press, Inc. p. 65. ISBN 978-1-365-65887-7.
- Stephen Hawking; "How to build a time machine", Mail Online 27 April 2010(retrieved 4 November 2014)
- Lawrence H. Ford and Thomas A. Roman; "Negative energy, wormholes and warp drive", Scientific American January 2000, 282, Pages 46–53. | <urn:uuid:8f061d0e-948c-43d0-a503-bfca627c1caf> | 3.859375 | 973 | Knowledge Article | Science & Tech. | 36.687503 | 95,585,528 |
Electric Field Strength or Electric Field Intensity
According to this law, the force ‘F’ between two point charges having charge Q1 and Q2 Coulomb and placed at a distance d meter from each other is given by, Here, εo is the permittivity of vacuum = 8.854 × 10-12 F/m and εr is the relative permittivity of the surrounding medium.
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Now, let us put Q2 = + 1 Coulomb and let us denote force F by E in the equation (1), and by doing these we get, This equation shows the force acting the a unit positive charge placed at a distance d from charge Q1.
As per definition this is nothing but of electric field strength of charge Q1 at a distance d from that charge. Now, we got the expression of electric field strength or intensity. Now, by combining this expression with equation (1), we get,
The above expression shows that, if we place a charge at any point in an electric field, the product of the electric field strength at that point and the charge of the body gives the force acting on the body at that point in the field. The above expression can also be rewritten as, Depending on this expression, the electric field strength can be expressed in Newton/Coulomb. The electric field strength has direction and hence it is vector quantity. Intensity means the magnitude or amount. Now field intensity similarly means the magnitude of the strength of the field. Finally electric field intensity or strength can be written as, So far we have discussed about the electric field intensity at a point due to the influence of a single charge, but there may be a case where, the point is under the filed of more than one charged bodies. In that case, we first have to calculate, the electric field strength at that point for individual charges and the we have to vectorially add up all the field strengths to get resultant field strength at that point. | <urn:uuid:d6d59745-cf1e-4f5c-85cb-c4194fdb74ff> | 3.90625 | 409 | Tutorial | Science & Tech. | 51.136471 | 95,585,531 |
On a clear August day in 2011, NASA launched a cube perched atop an Atlas V rocket that unfurled into a probe the size of a basketball court, complete with three whirling solar arrays.
That probe, named Juno in honor of the Roman god Jupiter’s wife, embarked on the first mission to map the mysterious inner workings of the largest planet in our solar system. The extraordinary five year journey involved a push through the inner solar system, a slingshot around the sun, a flyby of Earth and ultimately a capture by Jupiter’s gravity.
When Juno fires its main engines July 4, the journey will end as it slips into orbit above Jupiter. But the mission to explore what lies beneath the swirling clouds of gas will have just begun.
Excitement about the mission has been building in the scientific community — NASA’s website already has a countdown — and is just now spreading to the general public. Juno even has its own twitter account (@NASAJuno) with nearly a quarter-million followers.
Jupiter protects us from big cosmic collisions by taking hits and flinging things out of our solar system with its gravity. Without it, things would be much more chaotic. We need to understand how that works.
Bob Bonadurer, Milwaukee Public Museum
The Independence Day firing is critical; a reverse thrust generated during the burn will essentially slam on the brakes so the probe can skim over Jupiter and into a stable orbit. NASA expects to receive confirmation of the start of Juno’s engine burn at 8:18 p.m. and should know whether it worked by 8:53 p.m.
On July 4, Paul Borchardt, observatory director at the Milwaukee Astronomical Society in New Berlin, will eagerly be awaiting online mission updates for Juno.
“This is one of the fastest objects mankind has ever built,” Borchardt said, “and now NASA has to slow it down and bring it into orbit. If they don’t, the mission ends. If they do, then the real science begins.”
With its enormous magnetic field, Jupiter creates one of the brightest auroras ever observed despite being composed mostly of ammonia, hydrogen and helium. In some respects, Jupiter and its dozens of circling moons functions as almost a miniature solar system. Some astronomers even consider Jupiter a failed star.
Juno will be the first spacecraft to complete its orbits over Jupiter’s poles. Here, it will escape the brunt of the planet’s intense radiation and provide the first data from the uncharted regions from which the magnetic field emanates.
“Juno will go where no spacecraft has gone before — deep into the harshest radiation environment in the solar system outside the sun,” Rick Nybakken, Juno Project Manager from NASA’s Jet Propulsion Laboratory, explained during a recent news conference.
In November, public can vote for features that will get a close-up look
In an effort to prolong Juno’s survival, NASA housed the probe’s sensitive equipment in a 1 1/2-inch-thick titanium vault that cuts the radiation exposure by 800 fold.
Scott Bolton, Juno’s principal investigator, described the incredible efforts to ensure mission success. “Jupiter is the most extreme planet we have, and we are going right next to it. It’s got to do the extreme.”
Bob Bonadurer, director of theater and planetarium at the Milwaukee Public Museum, said people don’t realize how important the gas giant is to Earth.
“Jupiter protects us from big cosmic collisions by taking hits and flinging things out of our solar system with its gravity. Without it, things would be much more chaotic. We need to understand how that works.”
Incredibly high pressures and temperatures within Jupiter make the elements inside do some physically weird things. Specifically, scientists think the brutal conditions inside Jupiter force hydrogen into a fluid state, called “metallic hydrogen,” which is capable of conducting electricity.
By studying the charged particles and gravitational pull in the upper atmosphere, NASA will be able to determine whether metallic hydrogen is responsible for Jupiter’s powerful magnetic field. It should also reveal how deep the planet’s characteristic orange and white bands extend and if a solid core might be hidden at the center.
Moreover, scientists expect data from Juno to answer key questions about planetary formation and the origins of our solar system. Because Jupiter has a large mass, it has absorbed countless impacts from asteroids and comets unscathed and has retained the most intact material since the birth of the sun.
Each orbit will take 11 days, with Juno tracking different paths across Jupiter with its instruments and camera, JunoCam. Because Jupiter also will be rotating on its own axis, the entire planet will be surveyed inside and out by the end of the 37 planned orbits.
NASA expects the probe to survive Jupiter’s radiation onslaught through October 2017. At that point, the sensors will have endured radiation as strong as 100 million dental X-rays.
The first images should be publicly available at the end of August. Once the initial data is collected from the scientific instruments, NASA will point JunoCam at specific features to get more detailed images and then upload the photographic data in real time.
That is where NASA needs your help.
In November, voting will open for the public to choose which of these features will receive a close-up. The options range from the famous Great Red Spot where a storm has been raging for centuries, to a line of white storms known as the String of Pearls, to the planet’s north pole.
NASA expects the probe to survive Jupiter’s radiation onslaught through October 2017, by which time Juno’s sensors will have taken countless measurements and images. At that point, the sensors will have endured radiation as strong as 100 million dental X-rays.
That’s when the mission will end for Juno, which will be directed to plunge into Jupiter’s cloud tops and burn up like a meteor.
It will also be the end for the probe’s passengers: three spacecraft grade aluminum LEGO characters in the likenesses of Jupiter, Juno and Galileo. NASA included the figures on board in hopes of engaging children in scientific discovery and teaching them to “always reach to the stars.” | <urn:uuid:d5307f89-fe94-4970-b7bf-f567889971a5> | 3.75 | 1,313 | News Article | Science & Tech. | 46.083001 | 95,585,548 |
Carbon dioxide emissions from fossil fuels – the principal driver of climate change – have accelerated globally at a far greater rate than expected over recent years, according to a paper published this week in the Proceedings of the National Academy of Sciences.
The paper explains that the average growth rate of carbon dioxide emissions increased from 1.1 per cent a year in the 1990s to a three per cent increase per year in the 2000s.
Lead author of the paper, Dr Mike Raupach from CSIRO Marine and Atmospheric Research and the Global Carbon Project, says that nearly eight billion tonnes of carbon were emitted globally into the atmosphere as carbon dioxide in 2005, compared with just six billion tonnes in 1995.
"A major driver of the accelerating growth rate in emissions is that, globally, we’re burning more carbon per dollar of wealth created," Dr Raupach says. In the last few years, the global usage of fossil fuels has actually become less efficient. This adds to pressures from increasing population and wealth."
"As countries undergo industrial development, they move through a period of intensive, and often inefficient, use of fossil fuel. Efficiencies improve along this development trajectory, but eventually tend to level off. Industrialised countries such as Australia and the US are at the levelling-off stage, while developing countries such as China are at the intensive-development stage. Both factors are decreasing the global efficiency of fossil fuel use."
He says that China’s emissions per person are still below the global average. "On average, each person in Australia and the US now emits more than five tonnes of carbon per year, while in China the figure is only one tonne per year. Since the start of the industrial revolution, the US and Europe account for more than 50 per cent of the total, accumulated global emissions over two centuries, while China accounts for less than eight per cent. The 50 least developed countries have together contributed less than 0.5 per cent of global cumulative emissions over 200 years."
Dr Raupach says that Australia, with 0.32 per cent of the global population, contributes 1.43 per cent of the world’s carbon emissions.
He says recent efforts globally to reduce emissions have had little impact on emissions growth. "Recent emissions seem to be near the high end of the fossil fuel use scenarios used by the Intergovernmental Panel on Climate Change (IPCC). Our results add to previous findings that carbon dioxide concentrations, global temperatures and sea level rise are all near the high end of IPCC projections."
Dr Raupach led an international team of carbon-cycle experts, emissions experts and economists, brought together by the Global Carbon Project, to quantify global carbon emissions and their drivers.
"In addition to reinforcing the urgency of the need to reduce emissions, an important outcome of this work is to show that carbon emissions have history. We have to take both present and past emissions trajectories into account in negotiating global emissions reductions. To be effective, emissions reductions have to be both workable and equitable," he says.
Simon Torok | EurekAlert!
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine | <urn:uuid:900b7d8b-c7ce-4679-9289-9dfd049e5af6> | 3.484375 | 1,256 | Content Listing | Science & Tech. | 41.249029 | 95,585,597 |
MIT researchers have shown that a common pollutant strongly impacts the behavior of arsenic and possibly other toxic metals in some lakes, adding to scientists understanding of how such elements move through the water.
"The work shows that nitrate pollution, which arises from sources such as automobile exhaust, wastewater disposal and fertilizers, is more important in lake dynamics than had been thought," said Harry Hemond, the Leonhard Professor of Civil and Environmental Engineering and an author of a paper on the work that appeared in the June 28 issue of Science. "This is a linkage we need to understand if we want to manage water quality."
In an interesting twist, said Hemond, the nitrate pollution, which is also associated with noxious impacts such as excessive algal growth, was found to have a mitigating effect. It reacts with naturally occurring iron to create iron oxides that in turn adsorb arsenic. "The result is a suppression of seasonal arsenic release into the water," said Hemond, who is director of MITs Parsons Laboratory.
Elizabeth Thomson | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering | <urn:uuid:45f81a86-828e-462e-a876-1453a885408a> | 3.546875 | 872 | Content Listing | Science & Tech. | 38.003196 | 95,585,598 |
create_module - create a loadable module entry
caddr_t create_module(const char *name, size_t size);
: No declaration of this system call is provided in glibc headers;
: This system call is present only in kernels before Linux 2.6.
() attempts to create a loadable module entry and reserve
the kernel memory that will be needed to hold the module. This system call
On success, returns the kernel address at which the module will reside. On
error, -1 is returned and errno
is set appropriately.
- A module by that name already exists.
- name is outside the program's accessible address
- The requested size is too small even for the module header
- The kernel could not allocate a contiguous block of memory
large enough for the module.
- create_module() is not supported in this version of
the kernel (e.g., the kernel is version 2.6 or later).
- The caller was not privileged (did not have the
This system call is present on Linux only up until kernel 2.4; it was removed in
() is Linux-specific.
This obsolete system call is not supported by glibc. No declaration is provided
in glibc headers, but, through a quirk of history, glibc versions before 2.23
did export an ABI for this system call. Therefore, in order to employ this
system call, it was sufficient to manually declare the interface in your code;
alternatively, you could invoke the system call using syscall(2)
This page is part of release 4.16 of the Linux man-pages
description of the project, information about reporting bugs, and the latest
version of this page, can be found at | <urn:uuid:8864d2a5-d4c5-4c82-96e9-18a22644bf41> | 2.890625 | 374 | Documentation | Software Dev. | 51.794653 | 95,585,603 |
Executes an operating system command or program as a child process, synchronously. (Deprecated)
||Optional The operating system command or program to be executed as a child process, specified as a quoted string. If you omit program, $ZF(-1) launches the operating system shell.
is a deprecated function. It is described here for compatibility with existing code only. All new code development should use $ZF(-100)
permits an InterSystems IRIS process to invoke a program or a command of the host operating system. It executes the program or command specified in program
as a spawned child process from the current console. It executes synchronously; it waits for the process to return. $ZF(-1)
returns the child process exit status.
returns the following status codes:
It returns 0 if the child process executed successfully.
It returns a positive integer based on the exit status error code issued by the operating system shell. This integer exit status code value is determined by the host operating system. For example, for most Windows command syntax errors, $ZF(-1)
It returns -1 if the child process could not be forked.
waits for a response from the spawned child process, you cannot successfully shut down InterSystems IRIS while the child process is executing.
If a pathname supplied in program
contains a space character, pathname handling is platform-dependent. Windows and UNIX® permit space characters in pathnames, but the entire pathname containing spaces must be enclosed in an additional set of double quote (") characters. This is in accordance with the Windows cmd /c
statement. For further details, specify cmd /?
at the Windows command prompt.
is unable to spawn a process, it generates a <FUNCTION> error.
$ZF(-1), $ZF(-2), and $ZF(-100)
These three functions are in most respects identical. $ZF(-100)
is the preferred function for all purposes, replacing both $ZF(-1)
executes using the OS shell. It is synchronous; it suspends execution of the current process while awaiting completion of the spawned child process. It receives status information from the spawned process, which it returns as an exit status code (an integer value) when the spawned process completes. $ZF(-1)
does not set $ZCHILD
executes using the OS shell. It is asynchronous; it does not suspend execution of the current process. It immediately returns a status value upon spawning the child process. Because it does not await completion of the spawned child process it cannot receive status information from that process. $ZF(-2)
if its fifth argument is true.
can be synchronous or asynchronous. It can execute using the operating system shell or not using the shell. It always sets $ZCHILD
. Both $ZF(-1)
with no specified parameters launch the operating system shell; $ZF(-100)
requires a program
parameter (and the /SHELL
flag) to launch the operating system shell.
The following Windows example executes a user-written program, in this case displaying the contents of a .txt file. It uses NormalizeFilenameWithSpaces()
to handle a pathname for $ZF(-1)
. A pathname containing spaces is handled as appropriate for the host platform. A pathname that does not contain spaces is passed through unchanged. $ZF(-1)
returns the Windows shell exit status of 0 if the specified file could be accessed, or 1 if the file access failed:
SET fname="C:\My Test.txt"
The following Windows example invokes the Windows operating system SOL command. SOL opens a window that displays the Solitaire game provided with the Windows operating system. Upon closing of the Solitaire interactive window, $ZF(-1)
returns the Windows shell exit status of 0, indicating success:
The following Windows example invokes a non-existent Windows operating system command. $ZF(-1)
returns the Windows shell exit status of 1, indicating a syntax error:
The following Windows example invokes a Windows operating system command, specifying a non-existent network name. $ZF(-1)
returns the Windows shell exit error status of 2:
WRITE $ZF(-1,"NET USE :k \\bogusname") | <urn:uuid:0fb74eea-6527-4edd-bceb-22e0b77756de> | 2.5625 | 919 | Documentation | Software Dev. | 47.671977 | 95,585,633 |
In physics, a quantum vortex represents a quantized flux circulation of some physical quantity. In most cases quantum vortices are a type of topological defect exhibited in superfluids and superconductors. The existence of quantum vortices was predicted by Lars Onsager in 1947 in connection with superfluid helium. Onsager also pointed out that quantum vortices describe the circulation of superfluid and conjectured that their excitations are responsible for superfluid phase transitions. These ideas of Onsager were further developed by Richard Feynman in 1955 and in 1957 were applied to describe the magnetic phase diagram of type-II superconductors by Alexei Alexeyevich Abrikosov. In 1935 Fritz London published a very closely related work on magnetic flux quantization in superconductors. London's fluxoid can also be viewed as a quantum vortex.
Quantum vortices are observed experimentally in Type-II superconductors, liquid helium, and atomic gases (see Bose–Einstein condensate), as well as in photon fields (optical vortex) and exciton-polariton superfluids.
The term "quantum vortex" is also used in the study of few body problems. Under the De Broglie–Bohm theory, it is possible to derive a "velocity field" from the wave function. In this context, quantum vortices are zeros on the wave function, around which this velocity field has a solenoidal shape, similar to that of irrotational vortex on potential flows of traditional fluid dynamics
Vortex-quantisation in a superfluid
In a superfluid, a quantum vortex is a hole with the superfluid circulating around the vortex axis; the inside of the vortex may contain excited particles, air, vacuum, etc. The thickness of the vortex depends on a variety of factors; in liquid helium, the thickness is of the order of a few Angstroms.
A superfluid has the special property of having phase, given by the wavefunction, and the velocity of the superfluid is proportional to the gradient of the phase (in the parabolic mass approximation). The circulation around any closed loop in the superfluid is zero if the region enclosed is simply connected. The superfluid is deemed irrotational; however, if the enclosed region actually contains a smaller region with an absence of superfluid, for example a rod through the superfluid or a vortex, then the circulation is:
where is Planck's constant divided by , m is the mass of the superfluid particle, and is the total phase difference around the vortex. Because the wave-function must return to its same value after an integer number of turns around the vortex (similar to what is described in the Bohr model), then , where n is an integer. Thus, the circulation is quantized:
London's flux quantization in a superconductor
A principal property of superconductors is that they expel magnetic fields; this is called the Meissner effect. If the magnetic field becomes sufficiently strong, one scenario is for the superconductive state to be “quenched”. However, in some cases, it may be energetically favorable for the superconductor to form a lattice of quantum vortices, which carry Quantized magnetic flux through the superconductor. A superconductor that is capable of supporting vortex lattices is called a type-II superconductor, vortex-quantization in superconductors is general.
Over some enclosed area S, the magnetic flux is
- where is the vector potential of the magnetic induction
Substituting a result of London's equation: , we find (with ):
where ns, m, and es are, respectively, number density, mass, and charge of the Cooper pairs.
If the region, S, is large enough so that along , then
The flow of current can cause vortices in a superconductor to move, causing the electric field due to the phenomenon of electromagnetic induction. This leads to energy dissipation and causes the material to display a small amount of electrical resistance while in the superconducting state.
Constrained vortices in ferromagnets and antiferromagnets
The vortex states in ferromagnetic or antiferromagnetic material are also important, mainly for information technology They are exceptional, since in contrast to superfluids or superconducting material one has a more subtle mathematics: instead of the usual equation of the type where is the vorticity at the spatial and temporal coordinates, and where is the Dirac function, one has:
where now at any point and at any time there is the constraint . Here is constant, the constant magnitude of the non-constant magnetization vector . As a consequence the vector in eqn. (*) has been modified to a more complex entity . This leads, among other points, to the following fact:
In ferromagnetic or antiferromagnetic material a vortex can be moved to generate bits for information storage and recognition, corresponding, e.g., to changes of the quantum number n. But although the magnetization has the usual azimuthal direction, and although one has vorticity quantization as in superfluids, as long as the circular integration lines surround the central axis at far enough perpendicular distance, this apparent vortex magnetization will change with the distance from an azimuthal direction to an upward or downward one, as soon as the vortex center is approached.
Thus, for each directional element there are now not two, but four bits to be stored by a change of vorticity: The first two bits concern the sense of rotation, clockwise or counterclockwise; the remaining bits three and four concern the polarization of the central singular line, which may be polarized up- or downwards. The change of rotation and/or polarization involves subtle topology.
Statistical mechanics of vortex lines
As first discussed by Onsager and Feynman, if the temperature in a superfluid or a superconductor is raised, the vortex loops undergo a second-order phase transition. This happens when the configurational entropy overcomes the Boltzmann factor which suppresses the thermal or heat generation of vortex lines. The lines form a condensate. Since the center of the lines, the vortex cores, are normal liquid or normal conductors, respectively, the condensation transforms the superfluid or superconductor into the normal state. The ensembles of vortex lines and their phase transitions can be described efficiently by a gauge theory.
- Wells, Frederick S.; Pan, Alexey V.; Wang, X. Renshaw; Fedoseev, Sergey A.; Hilgenkamp, Hans (2015). "Analysis of low-field isotropic vortex glass containing vortex groups in YBa2Cu3O7−x thin films visualized by scanning SQUID microscopy". Scientific Reports. 5: 8677. Bibcode:2015NatSR...5E8677W. doi:10.1038/srep08677. PMC . PMID 25728772.
- Feynman, R. P. (1955). "Application of quantum mechanics to liquid helium". Progress in Low Temperature Physics. Progress in Low Temperature Physics. 1: 17–53. doi:10.1016/S0079-6417(08)60077-3. ISBN 978-0-444-53307-4.
- *Abrikosov, A. A. (1957) "On the Magnetic properties of superconductors of the second group[permanent dead link]", Sov. Phys. JETP 5:1174–1182 and Zh. Eksp. Teor. Fiz. 32:1442–1452.
- Macek, J. H.; Sternberg, J. B.; Ovchinnikov, S. Y.; Briggs, J. S. (2010-01-20). "Theory of Deep Minima in $(e,2e)$ Measurements of Triply Differential Cross Sections". Physical Review Letters. 104 (3): 033201. Bibcode:2010PhRvL.104c3201M. doi:10.1103/PhysRevLett.104.033201.
- Navarrete, F; Picca, R Della; Fiol, J; Barrachina, R O. "Vortices in ionization collisions by positron impact". Journal of Physics B: Atomic, Molecular and Optical Physics. 46 (11). arXiv: . Bibcode:2013JPhB...46k5203N. doi:10.1088/0953-4075/46/11/115203.
- "First vortex 'chains' observed in engineered superconductor". Physorg.com. June 20, 2017. Retrieved 2011-03-23.
- Magnetic vortices in nanodisks reveal information. Phys.org (March 3, 2015).
- Pylipovskyi, O.V. et al. (January 2015) "Polarity Switching in Magnets with Surface Anisotropy. arxiv.org | <urn:uuid:b9abfbb2-3d61-4d84-b605-45058242737e> | 3.40625 | 1,898 | Knowledge Article | Science & Tech. | 44.984187 | 95,585,679 |
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Growth and Grazing of the Arctic Picophytoplankton from Winter to Spring
|Autor:||Rodríguez-Martínez, Raquel ; Massana, Ramon ; Pedrós-Alió, Carlos|
|Fecha de publicación:||23-abr-2012|
|Citación:||IPY2012 Conference Montréal (2012)|
|Resumen:||Polar waters during winter are still one of the least known ecosystems in the world due to remoteness and harsh conditions. Yet, winter ecology is the necessary previous step for everything that occurs during spring and summer. The Canadian IPY project Circumpolar Flaw Lead Polynya Study (on board of the CCGS Amundsen) included a time series from the darkest (December 2007) to the most lit times of the year (June 2008) in Amundsen Gulf, a dynamic area due to the presence of a polynya. Our objective was to determine the activities and trophic relationships of planktonic microorganisms during winter. We observed that chlorophyll a decreased during the fall and early winter as expected. In middle February, however, chlorophyll started to increase exponentially despite the low light levels. This could be attributed to small flagellates, particularly Micromonas. This growth was followed by an increase in large flagellates that likely fed on these algae. Heterotrophic bacteria increased in numbers about a month later than the algal bloom and bacterivory by small pico and nanoflagellates followed. Thus, the first link of the trophic chain to become active after the total darkness period was autotrophic picoflagellates (mostly Micromonas) to large nanoflagellates. As a first approach to determine the role of this picophytoplankton we carried out several grazing experiments starting in winter (January 2008). We did 96-hour incubations with the in situ predator-prey community and an external alive Micromonas culture (RCC497 strain) as a tracer. The fascinating thing was that the grazing rates on Micromonas obtained were of the same order of magnitude as the in situ net death rates of the algae during December and January. This suggests that the decrease in chlorophyll a was not due to lack of light but to grazing. That is, the algae were able to subsist for a few months despite the absence of light. This is of larger significance, since it has been shown that this Micromonas phylotype is an Arctic endemism and is widespread throughout the Arctic Ocean, presumably playing a role similar to that of cyanobacteria at lower altitudes|
|Descripción:||IPY2012 Conference Montréal. From Knowledge to Action, 22-27 April 2012, Montréal, Canada|
|Versión del editor:||http://220.127.116.11/2012-ipy/Abstracts_On_the_Web/authors.html|
|Aparece en las colecciones:||(ICM) Comunicaciones congresos|
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This series is made for the beginners who is novice in dart programming language
Dart is a general-purpose programming language originally developed by Google and later approved as a standard by Ecma. It is used to build web, server and mobile applications, and for Internet of Things devices.
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As has been widely reported, the J. Craig Venter Institute and other facilities are working to assemble the world's first synthetic organism from the bottom up. The goal is to create life from non-life. Science News has a great introduction to the science of synthetic life. (This article does not delve into the debate about whether synthetic organisms should be patentable.) From Science News:
"Simplicity has always been where we try to gain understanding," says John Glass of the J. Craig Venter Institute in Rockville, Md. "In a way, what we're doing is making a better platform for understanding what life is." It's a bit like learning the essentials of how a luxury car works by building a dune buggy from spare parts.
Some scientists, including Glass, hope to make such a minimal cell by whittling down the genome of an existing bacterium to its barest elements, and then synthesizing that minimal genome. In the lab, scientists can assemble the genomic DNA by piecing together chemicals called nucleotides, which constitute the individual letters of genetic code.
Other scientists, starting from long lists of molecules and genes, are devising plans to assemble these parts to make an entire cell, not just its genome, by hand.
Still other researchers take a radically different approach. Instead of trying to construct cells from the same proteins and DNA found in modern organisms, these investigators hope to assemble a cell from more-primitive molecules that better mimic the molecules probably involved in the origin of life. If successful, these scientists may uncover clues about how the original "spontaneous generation" of life occurred billions of years ago.
Do you own a Samsung smartphone? Do you take photos with said phone? Congratulations, there’s an excellent chance that your handset is randomly firing off those pictures you’ve snapped to folks on your contact list without your permission. According to The Verge, the images are being pushed out by Samsung’s cleverly named default messaging app, […]
When you live full-time in a motorhome, no matter how big it is, there’s not a lot of room for extras. In order to have enough space to be comfortable, its necessary to strip your belongings down to the essentials. A library full of books gives way to e-readers and tablets. Full-sized anything? You’re gonna […]
On Monday, the Supreme Court will review the 9th Circuit's decision in Apple Inc. v. Pepper, in which the plaintiffs argue that Apple has established a monopoly over apps for Ios (this part is actually incontrovertible, as Apple has used both technology and law to prevent rival app stores from operating), and that Iphone and […]
Summer’s here, which brings not only warmer weather but also the unsettling realization that the year is more than halfway over. So, for those who weren’t as productive as they would have liked during the first half of 2018, we’ve rounded up 5 skill course bundles you can start learning today to help you finish […]
It’s good to be proactive, but when it comes to preparing for an emergency situation, one of the most important items you can pack is a flashlight. After all, whatever else you include in your kit won’t be of much use if you can’t see what you’re doing. The Viper 1000-Lumen Tactical Flashlights not only […]
Chances are you took a handful of language classes in high school, and aside from a smattering of conjugations and vocabulary words, the only things you likely remember are the dry, rehearsed sentences that did little to make you speak like a true native. If you’re still hoping to learn a new language but want […] | <urn:uuid:925bfe66-0fda-44aa-96ee-9338c6f4c87a> | 3.171875 | 776 | Content Listing | Science & Tech. | 46.419789 | 95,585,741 |
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The representation of executables, shared libraries and relocatable object code is standardized by a variety of file formats which provides encapsulation of assembly instructions and data. Two such formats are the Portable Executable (PE) file format and the Executable and Linkable Format (ELF), which are used by Windows and Linux respectively. Both of these formats partition executable code and data into sections and assign appropriate access permissions to each section, as summarised by table 1. In general, no single section has both write and execute permissions as this could compromise the security of the system.
|Section name||Usage description||Access permissions|
Table 1: A summary of the most commonly used sections in ELF files. The
.text section contains executable code while the
.bss sections contains data in various forms.
To gain a better understanding of the anatomy of executables the remainder of this section describes the structure of ELF files and presents the dissection of a simple
hello world ELF executable, largely inspired by Eric Youngdale's article on The ELF Object File Format by Dissection. Although the ELF and PE file formats differ with regards to specific details, the general principles are applicable to both formats.
In general, ELF files consist of a file header, zero or more program headers, zero or more section headers and data referred to by the program or section headers, as depicted in figure 1.
Figure 1: The basic structure of an ELF file.
All ELF files starts with the four byte identifier
'F' which marks the beginning of the ELF file header. The ELF file header contains general information about a binary, such as its object file type (executable, relocatable or shared object), its assembly architecture (x86-64, ARM, ), the virtual address of its entry point which indicates the starting point of program execution, and the file offsets to the program and section headers.
Each program and section header describes a continuous segment or section of memory respectively. In general, segments are used by the linker to load executables into memory with correct access permissions, while sections are used by the compiler to categorize data and instructions. Therefore, the program headers are optional for relocatable and shared objects, while the section headers are optional for executables.
Figure 2: The entire contents of a simple
hello world ELF executable with colour-coded file offsets, sections, segments and program headers. Each file offset is 8 bytes in width and coloured using a darker shade of its corresponding segment, section or program header.
To further investigate the structure of ELF files a simple 64-bit
hello world executable has been dissected and its content colour-coded. Each file offset of the executable consists of 8 bytes and is denoted in figure 2 with a darker shade of the colour used by its corresponding target segment, section or program header. Starting at the middle of the ELF file header, at offset
0x20, is the file offset (red) to the program table (bright red). The program table contains five program headers which specify the size and file offsets of two sections and three segments, namely the
.interp (gray) and the
.dynamic (purple) sections, and a read-only (blue), a read-write (green) and a read-execute (yellow) segment.
Several sections are contained within the three segments. The read-only segment contains the following sections:
.interp: the interpreter, i.e. the linker
.dynamic: array of dynamic entities
.dynstr: dynamic string table
.dynsym: dynamic symbol table
.rela.plt: relocation entities of the PLT
.rodata: read-only data section
The read-write segment contains the following section:
.got.plt: Global Offset Table (GOT) of the PLT (henceforth referred to as the GOT as this executable only contains one such table)
And the read-execute segment contains the following sections:
.plt: Procedure Linkage Table (PLT)
.text: executable code section
Seven of the nine sections contained within the executable are directly related to dynamic linking. The
.interp section specifies the linker (in this case
/lib/ld64.so.1) and the
.dynamic section an array of dynamic entities containing offsets and virtual addresses to relevant dynamic linking information. In this case the dynamic array specifies that
libc.so.6 is a required library, and contains the virtual addresses to the
.got.plt sections. As noted, even a simple
hello world executable requires a large number of sections related to dynamic linking. Further analysis will reveal their relation to each other and describe their usage.
The dynamic string table contains the names of libraries (e.g.
libc.so.6) and identifiers (e.g.
printf) which are required for dynamic linking. Other sections refer to these strings using offsets into
.dynstr. The dynamic symbol table declares an array of dynamic symbol entities, each specifying the name (e.g. offset to
.dynstr) and binding information (local or global) of a dynamic symbol. Both the
.plt and the
.rela.plt sections refers to these dynamic symbols using array indicies. The
.rela.plt section specifies the relocation entities of the PLT; more specifically this section informs the linker of the virtual address to the
.exit entities in the GOT.
To reflect on how dynamic linking is accomplished on a Linux system lets review the assembly instructions of the executable
.plt sections as outlined by figure 3 and 4 respectively.
text: .start: mov rdi, rodata.hello call plt.printf mov rdi, 0 call plt.exit
Figure 3: The assembly instructions of the
plt: .resolve: push [got_plt.link_map] jmp [got_plt.dl_runtime_resolve] .printf: jmp [got_plt.printf] .resolve_printf: push dynsym.printf_idx jmp .resolve .exit: jmp [got_plt.exit] .resolve_exit: push dynsym.exit_idx jmp .resolve
Figure 4: The assembly instructions of the
As visualized in figure 3 the first call instruction of the
.text section targets the
.printf label of the
.plt section instead of the actual address of the printf function in the libc library. The Procedure Linkage Table (PLT) provides a level of indirection between call instructions and actual function (procedure) addresses, and contains one entity per external function as outlined in figure 4. The
.printf entity of the PLT contains a jump instruction which targets the address stored in the
.printf entity of the GOT. Initially this address points to the next instruction, i.e. the instruction denoted by the
.resolve_printf label in the PLT. On the first invokation of printf the linker replaces this address with the actual address of the printf function in the libc library, and any subsequent invokation of printf will target the resolved function address directly.
This method of external function resolution is called lazy dynamic linking as it postpones the work and only resolves a function once it is actually invoked at runtime. The lazy approach to dynamic linking may improve performance by limiting the number of symbols that require resolution. At the same time the eager approach may benefit latency sensitive applications which cannot afford the cost of dynamic linking at runtime.
A closer look at the instructions denoted by the
.resolve_printf label in figure 4 reveals how the linker knows which function to resolve. Essentially the dl_runtime_resolve function is invoked with two arguments, namely the dynamic symbol index of the printf function and a pointer to a linked list of nodes, each refering to the
.dynamic section of a shared object. Upon termination the linked list of our
hello world process contains a total of four nodes, one for the executable itself and three for its dynamically loaded libraries, namely linux-vdso.so.1, libc.so.6 and ld64.so.1.
To summarise, the execution of a dynamically linked executable can roughly be described as follows. Upon execution the kernel parses the program headers of the ELF file, maps each segment to one or more pages in memory with appropriate access permissions, and transfers the control of execution to the linker (
/lib/ld64.so.1) which was loaded in a similar fashion. The linker is responsible for initiating the addresses of the dl_runtime_resolve function and the aforementioned linked list, both of which are stored in the GOT of the executable. After this setup is complete the linker transfers control to the entry point of the executable, as specified by the ELF file header (in this case the
.start label of the
.text section). At this point the assembly instructions of the application are executed until termination and external functions are lazily resolved at runtime by the linker through invokations to the dl_runtime_resolve function.
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Prescribed fire in a Great Basin sagebrush ecosystem: Dynamics of soil extractable nitrogen and phosphorusAuthor(s): B. M. Rau; R. R. Blank; J. C. Chambers; D. W. Johnson
Source: Journal of Arid Environments. 71: 362-375.
Publication Series: Miscellaneous Publication
PDF: View PDF (320 B)
DescriptionPinyon and juniper have been expanding into sagebrush (Artemisia tridentata) ecosystems since settlement of the Great Basin around 1860. Herbaceous understory vegetation is eliminated as stand densities increase and the potential for catastrophic fires increases. Prescribed fire is increasingly used to remove trees and promote recovery of sagebrush ecosystems.
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CitationRau, B. M.; Blank, R. R.; Chambers, J. C.; Johnson, D. W. 2007. Prescribed fire in a Great Basin sagebrush ecosystem: Dynamics of soil extractable nitrogen and phosphorus. Journal of Arid Environments. 71: 362-375.
Keywordsburning, ecosystem succession, juniper, pinyon, soil nutrients
- Big sagebrush in pinyon-juniper woodlands: Using forest inventory and analysis data as a management tool for quantifying and monitoring mule deer habitat
- Fire rehabilitation using native and introduced species: A landscape trial
- Bird habitat relationships along a Great Basin elevational gradient
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The tutorial guides you through creating code to connect to and query a database from the client. Alternatively, you can specify the classpath on the Java command line that runs the application by using the java -classpath option. If you are already familiar with the getConnection method, you can skip ahead to either of these sections, depending on the driver you installed:. The Import statements tell the Java compiler where to find the classes you reference in your code and are placed at the very beginning of your source code. Connection Pooling with Spring. Once again, this is standard JDBC syntax. However, this method is valid only for JDK-compliant Java virtual machines.
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Java applets run register jdbc a browser but are downloaded from a web server. Likewise deregister will only remove one instance regardless of how many times it was registered.
Therefore, applications do not need to call the Class. For more information on Oracle extensions, see Chapter 4, “Oracle Extensions”.
Driver” file, which contains the com. David O’Meara 2, 15 With this method, you could use an external register jdbc file to supply the driver class name and driver parameters to use when connecting to a database.
I don’t understand what you’re trying to jdbv. Registering the driver is the process by which the Oracle driver’s class file is loaded into the memory, so register jdbc can be utilized as an implementation of the JDBC interfaces. Register jdbc Sauer k 47 Finally, code a call to the DriverManager object’s getConnection method to establish actual database connection.
java – JDBC e vs erDriver – Stack Overflow
You can register a driver in one of two ways. The registerDriver method takes as input a “driver” class, that is, a class that register jdbc the java. Pacerier It register jdbc public because driver register jdbc need to be able to call it to register themselves.
The following example connects user scott with password tiger to a database with SID orcl through port of host myhostusing the Thin driver. EJB containers are sourced from various vendors. If you are writing a connection statement for an applet, you must enter a connect string that is different from the one used in these examples.
To connect to and query a database register jdbc the client, you must provide code for these tasks:. To continue the example from the previous reegister where the Connection object conn was created, register jdbc is an example of how to create the Statement object:. Old comments will not be carried over.
OracleDriver (Oracle ® Database JDBC API Reference)
Ok, but If I use registerDriver than I must load the class into memory? Creating a Statement Object Once you connect to the database and, in the process, create your Connection object, the next step is to create a Statement object. For example, if your ResultSet object is rset and your Statement revister is stmtclose the result set and statement with these lines:. After the driver has been registered with the DriverManageryou can obtain a Registre instance that is connected reyister a particular database by calling DriverManager.
If you are registering a Thin driver in an applet, you must enter a driver string that is different from the one used in these examples.
Register the JDBC drivers
A database URL register jdbc an address that jvbc to your database. You do not have to specify the database name if there is a default connection.
All the highlighted part in URL format is static and you need register jdbc change only the remaining part as per your database setup. When you close a Statement object that a given Connection object creates, the connection itself remains open.
Once again, this register jdbc standard JDBC syntax.
Failing so availability on runtime would result in NoClassDefFoundError which you usually would not like to deal with. | <urn:uuid:a307426a-f128-46cd-81c0-749399f4541f> | 2.875 | 899 | Tutorial | Software Dev. | 46.713382 | 95,585,749 |
Infrared sensor satellites, which consist of cryogenic infrared sensor detectors, electrical instrumentation, and data acquisition systems, are used to monitor the conditions of the earth's upper atmosphere in order to evaluate its present and future changes. Currently, the electrical connections (instrumentation), which act as thermal bridges between the cryogenic infrared sensor and the significantly warmer data acquisition unit of the sensor satellite system, constitute a significant portion of the heat load on the cryogen. As a part of extending the mission life of the sensor satellite system, the researchers at the National Aeronautics and Space Administration's Langley Research Center (NASA-LaRC) are evaluating the effectiveness of replacing the currently used manganin wires with high-temperature superconductive (HTS) materials as the electrical connections (thermal bridges). In conjunction with the study being conducted at NASA-LaRC, the proposed research is to design a space experiment to determine the thermal savings on a cryogenic subsystem when manganin leads are replaced by HTS leads printed onto a substrate with a low thermal conductivity, and to determine the thermal conductivities of HTS materials. The experiment is designed to compare manganin wires with two different types of superconductors on substrates by determining the heat loss by the thermal bridges and providing temperature measurements for the estimation of thermal conductivity. A conductive mathematical model has been developed and used as a key tool in the design process and subsequent analysis. | <urn:uuid:17bffb1e-b9f1-4a11-9d35-a78d3647ca7b> | 2.890625 | 294 | Knowledge Article | Science & Tech. | -6.439167 | 95,585,752 |
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Farmer John's farm is in the shape of an N×N grid of fields (2≤N≤18), each labeled with a letter in the alphabet. For example:
ABCD BXZX CDXB WCBA
Each day, Bessie the cow walks from the upper-left field to the lower-right field, each step taking her either one field to the right or one field downward. Bessie keeps track of the string that she generates during this process, built from the letters she walks across. She gets very disoriented, however, if this string is a palindrome (reading the same forward as backward), since she gets confused about which direction she had walked.
Please help Bessie determine the number of different palindromes she can form during her walk. Different ways of forming the same palindrome only count once; for example, there are several routes that yield the palindrome ABXZXBA above, but there are only four distinct palindromes Bessie can form, ABCDCBA, ABCWCBA, ABXZXBA, ABXDXBA.
The first line of input contains N, and the remaining N lines contain the N rows of the grid of fields. Each row contains N characters that are in the range A..Z.
Please output the number of distinct palindromes Bessie can form.
4 ABCD BXZX CDXB WCBA | <urn:uuid:253df81a-e157-456f-8537-fd515399a3a3> | 2.828125 | 386 | Q&A Forum | Science & Tech. | 74.669609 | 95,585,756 |
Page Count647 Pages
About the e-Book
macOS Programming for Absolute Beginners pdf
Learn how to code for the iMac, Mac mini, Mac Pro, and MacBook using Swift, Apple's hottest programming language.
Fully updated to cover the new MacBook Touch Bar, macOS Programming for Absolute Beginners will not only teach complete programming novices how to write macOS programs, but it can also help experienced programmers moving to the Mac for the first time. You will learn the principles of programming, how to use Swift and Xcode, and how to combine your knowledge into writing macOS programs.
If you've always wanted to learn coding but felt stymied by the limitation of simplistic programming languages or intimidated by professional but complicated programming languages, then you'll want to learn Swift. Swift is your gateway to both Mac and iOS app development while being powerful and easy to learn at the same time, and macOS Programming for Absolute Beginners is the perfect place to start - add it to your library today.
What You'll Learn
- Master the basic principles of object-oriented programming
- Use Xcode, the main programming tool used for both macOS and iOS development
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- Take advantage of the new Touch Bar
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Reactions of Alkenes . Addition of HOX; X: Cl, Br. CCl 4. Ozonolysis. Ozonolysis. Reaction Mechanism. A reaction mechanism describes how a reaction occurs which bonds are broken and which new ones are formed the order in which bond-breaking and bond-forming steps take place
Nucleophile(nucleus loving): An electron rich species that seeks a region of low electron density.
Step 2: a Lewis acid/base reaction gives an oxonium ion
Step 3: proton transfer to solvent gives the alcohol | <urn:uuid:a349395d-ee0a-4528-8242-353d21614a19> | 3.125 | 120 | Knowledge Article | Science & Tech. | 55.645 | 95,585,776 |
With the first detailed observations of a lava lake on a moon of Jupiter, the Large Binocular Telescope Observatory in Arizona places itself as the forerunner of the next generation of Extremely Large Telescopes. The applied high-resolution imaging methods were developed by an international research team including scientists from the Max Planck Institute for Radio Astronomy in Bonn and the Max Planck Institute for Astronomy in Heidelberg.
Io, the innermost of the four moons of Jupiter discovered by Galileo in January 1610, is only slightly bigger than our own Moon but is the most geologically active body in our solar system. Hundreds of volcanic areas dot its surface, which is mostly covered with sulfur and sulfur dioxide.
The LBT image of the Loki lava lake (orange) laid over a Voyager image of the same structure (dark shade).
LBTO / NASA
The largest of these volcanic features, named Loki after the Norse god often associated with fire and chaos, is a volcanic depression called patera in which the denser lava crust solidifying on top of a lava lake episodically sinks in the lake, yielding a raise in the thermal emission which has been regularly observed from Earth. Loki, only 200km in diameter and at least 600 million km from Earth, was, up to recently, too small to be looked at in details from any ground based optical/infrared telescope.
With its two 8.4 m mirrors set on the same mount 6 m apart, the Large Binocular Telescope (LBT) has been designed to ultimately provide images with the level of details a 22.8 m telescope would, by combining the light through interferometry. Thanks to the Large Binocular Telescope Interferometer (LBTI), an international team of researchers was able to look at Loki Patera in details for the first time from Earth in a study published today in the Astronomical Journal.
"We combine the light from two very large mirrors coherently so that they become a single, extremely large mirror,” says Al Conrad, the lead of the study and a Scientist at the Large Binocular Telescope Observatory (LBTO). “In this way, for the first time we can measure the brightness coming from different regions within the lake."
For Phil Hinz, who leads the LBTI project at the University of Arizona Steward Observatory, this result is the outcome of a nearly fifteen year development. "We built LBTI to form extremely sharp images. It is gratifying to see the system work so well." Phil notes that this is only one of the unique aspects of LBTI. "We built the system both to form sharp images and to detect dust and planets around nearby stars at extremely high dynamic range. The new result from LBTI is a great example of its potential."
LMIRcam, the camera recording the images at the very heart of LBTI in the 3 to 5 micrometers near-infrared band, was the thesis work of Jarron Leisenring as graduate student at the University of Virginia. For Jarron, now an instrument scientist for NIRCam (the Near InfraRed CAMera for the James Webb Space Telescope) at Steward Observatory, "these observations mark a major milestone for me and the instrument team. LMIRcam has already been very productive these past few years; now, interferometric combination provides the last step in harnessing LBTI’s full potential and enabling a whole host of new scientific opportunities."
Many raw images delivered by LMIRcam are combined to form a single high-resolution image. "LBTI raw images are crossed by interference fringes. Therefore, these raw images do not look very sharp", explains Gerd Weigelt, a Professor at the Max-Planck-Institut für Radioastronomie in Bonn, Germany. "However, modern image reconstruction methods, so-called deconvolution, allow us to overcome the interference fringes and achieve a spectacular image resolution.”
"Data processing based on deconvolution methods", adds Mario Bertero, a professor in Information Science at the University of Genova (Italy), "are basic for detecting details not directly distinguishable in the interferometric images. However they can generate artifacts and, for this reason, it is important to process the images with different methods for discriminating between relevant details and artifacts.”
"While we have seen bright emissions – always one unresolved spot – “pop-up” at different locations in Loki Patera over the years”, explains Imke de Pater, a Professor at the University of California in Berkeley, "these exquisite images from the LBTI show for the first time in ground based images that emissions arise simultaneously from different sites in Loki Patera. This strongly suggests that the horseshoe-shaped feature is most likely an active overturning lava lake, as hypothesized in the past.”
"Two of the volcanic features are at newly-active locations", explains Katherine de Kleer, a graduate student at the University of California at Berkeley. "They are located in a region called the Colchis Regio, where an enormous eruption took place just a few months earlier, and may represent the aftermath of that eruption. The high resolution of the LBTI allows us to resolve the residual activity in this region into specific active sites, which could be lava flows or nearby eruptions."
"Studying the very dynamic volcanic activity on Io, which is constantly reshaping the moon's surface, provides clues to the interior structure and plumbing of this moon," remarked team member Chick Woodward of the University of Minnesota. "It helps to pave the way for future NASA missions such as the Io Observer. Io's highly elliptical orbit close to Jupiter is constantly tidally stressing the moon, like the squeezing of a ripe orange, where the juice can escape through cracks in the peel."
For Christian Veillet, Director of the Large Binocular Telescope Observatory (LBTO), "this study marks a very important milestone for the Observatory. The unique feature of the binocular design of the telescope, originally proposed more than 25 years ago, is its ability to provide images with the level of detail (resolution) only a single-aperture telescope at least 22.7m in diameter could reach. The spectacular observations of Io published today are a tribute to the many who believed in the LBT concept and worked very hard over more than two decades to reach this milestone."
Veillet adds: "While there is still much work ahead to make the LBT/LBTI combination a fully operational instrument, we can safely state that the Large Binocular Telescope is truly a forerunner of the next generation of Extremely Large Telescopes slated to see first light in a decade (or more) from now."
The Large Binocular Telescope (LBT) is an international collaboration among institutions in the U.S., Italy and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia. The Large Binocular Telescope Interferometer is funded by NASA as part of its Exoplanet Exploration program. LMIRcam is funded by the National Science Foundation through grant NSF AST-0705296. The research was partially supported by the National Science Foundation, NSF Grant AST-1313485 to UC Berkeley, and by the National Science Foundation Graduate Research Fellowship under Grant DGE-1106400.
The research team is led by Albert Conrad from the LBT Observatory (University of Arizona). Besides the local members Karl-Heinz Hofmann, Dieter Schertl and Gerd Weigelt (all Max Planck Institute for Radio Astronomy, Bonn) it comprises Katherine de Kleer and Imke de Pater (both University of California at Berkeley), Jarron Leisenring, Denis Defrère, Philip Hinz and Andy Skemer (all University of Arizona), Andrea la Camera, Mario Bertero and Patricia Boccacci (all DIBRIS, University of Genua), Carmelo Arcidiacono (INAF, Osservatorio Astronomico di Bologna), Martin Kürster (Max Planck Institute for Astronomy, Heidelberg), Julie Rathbun (Planetary Science Institute, Tucson), Michael Skrutskie (University of Virginia), John Spencer (Southwest Research Institute, Boulder), Christian Veillet (LBT Observatory) and Charles E. Woodward (Minnesota Institute for Astrophysics).
Spatially resolved M-band emission from Io's Loki patera - Fizeau imaging at the 22.8m LBT, Albert Conrad et al., 2015, Astronomical Journal:
Prof. Dr. Gerd Weigelt,
Max-Planck-Institut für Radioastronomie, Bonn.
Dr. Karl-Heinz Hofmann
Max-Planck-Institut für Radioastronomie, Bonn.
Dr. Dieter Schertl
Max-Planck-Institut für Radioastronomie, Bonn.
Dr. Norbert Junkes,
Press and Public Outreach,
Max-Planck-Institut für Radioastronomie.
Norbert Junkes | Max-Planck-Institut für Radioastronomie
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...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:d5c0f3aa-0e81-43af-91ef-039d0ef69fc6> | 3.765625 | 2,628 | Content Listing | Science & Tech. | 31.05575 | 95,585,785 |
Dr Loretta Dunne and her team have found new evidence of huge dust production in the Cassiopeia A supernova remnant, the remains of a star that exploded about 300 years ago. The paper is set to be published in the Monthly Notices of the Royal Astronomical Society.
Interstellar dust is found throughout the cosmos. It is responsible for the dark patches seen in the Milky Way on a moonless night. It consists of carbon and silicate particles, about the size of those in cigarette smoke. The dust helps stars like the Sun to form and subsequently coagulates to form planets like Earth and the cores of giant gas planets like Jupiter. It is found in huge quantities in galaxies, even very early in the history of the universe.
But the origin of all this dust is a mystery. Does it condense like snowflakes in the winds of red giant stars or is it produced in supernovae — the violent death-throes of massive stars? Supernovae are an efficient way of producing dust in a blink of the cosmic eye, as massive stars evolve relatively quickly, taking a few million years to reach their supernova stage. In contrast lower-mass stars like our Sun take billions of years to reach their dust-forming red giant phase. Despite many decades of research, astronomers have still not found conclusive evidence that supernovae can produce dust in the quantities required to account for the dust they see in the early universe.
Using the SCUBA polarimeter on the James Clerk Maxwell Telescope in Hawaii, the scientists searched for a signal from dust grains spinning in the strong magnetic field of the supernova remnant. If the dust grains are slightly elongated (like little cigars) they tend to line up the same way and produce a polarised signal. When the polarimeter detector is rotated, the strength of the signal changes — much the same as if you look at the sky with polaroid sunglasses, held at different angles.
The polarisation signal from the supernova dust is the strongest ever measured anywhere in the Milky Way, marking it out as unusual. It emits more radiation per gram than regular interstellar dust and the alignment of the grains must be very orderly to produce such highly polarised emission.
“It is like nothing we’ve ever seen” said Dr Dunne, who is based in the Centre for Astronomy and Particle Physics at The University of Nottingham. “It could be that the extreme conditions inside the supernova remnant are responsible for the strong polarised signal, or it could be that the dust grains themselves are highly unusual”
Team member Professor Rob Ivison of the UK Astronomy Technology Centre at the Institute for Astronomy, University of Edinburgh comments further. “It could be that the material we're seeing is in the form of iron needles — exotic, slender, metallic whiskers. If these grains are distributed throughout the Universe they may be re-radiating microwaves. This has major consequences for our understanding of the cosmic microwave background — one of the most important building blocks of the Big Bang model of our Universe”.
Alternatively, the grains could be a more pristine version of the dust found elsewhere in the Galaxy, the same composition but able to produce more radiation due to the nuances of its 3-D structure. A final verdict requires further observations using the Herschel Space Observatory, to be launched this year by the European Space Agency.
Dr Loretta Dunne | EurekAlert!
Further reports about: > Astronomy > Big Bang > Cassiopeia A > Cassiopeia A supernova remnant > Cosmos > Dust > Dust factory > Jupiter > Milky Way > Space > Sun > Supernovae > dead star > early universe > galaxies > giant gas planets > massive stars > moonless night > polarisation signal > re-radiating microwaves
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:55b2cbad-042d-47e7-8b24-07abc728ba16> | 4.15625 | 1,423 | Content Listing | Science & Tech. | 38.825049 | 95,585,796 |
In plants and animals, soft living tissues routinely adopt complex 3D structures to perform or enhance critical functions. Although such structures have applications in biomedical engineering, robotics, and flexible electronics, most efforts to synthesize them in soft materials diverge fundamentally from biological processes.
Researchers present a technique to direct the polymerization of monomers to form complex 3D architectures from porous hydrogels. Mimicking organic tissue morphogenesis, in which constituents within a single tissue grow at different rates and impose mechanical restraints, the technique modulates oxygen diffusion-inhibited polymerization to enable the formation of engineered heterogeneous, patterned structures. Depending on the patterning, the prefabricated structures self-organize and evolve into a desired configuration.
The strategy effectively utilizes the three essential components dictating living tissue morphogenesis to produce complex 3D architectures: modulation of local chemistry, material transport, and mechanics, which can be engineered by controlling the local distribution of polymerization inhibitor (i.e., oxygen), diffusion of monomers/cross-linkers through the porous structures of cross-linked polymer network, and mechanical constraints, respectively.
They show that oxygen plays a role in hydrogel polymerization which is mechanistically similar to the role of growth factors in tissue growth, and the continued growth of hydrogel enabled by diffusion of monomers/cross-linkers into the porous hydrogel similar to the mechanisms of tissue growth enabled by material transport.
The authors used the technique to generate a variety of biomimetic structures corresponding to plant and animal tissues, including bending in a plant stem and structural changes seen in the respiratory airways of asthma patients.
The findings offer an approach to study and replicate complex soft tissue architectures, according to the authors.
Generating complex 3D structures in soft materials
- 776 views | <urn:uuid:8ffb62b1-b458-4205-8667-599671f2cd8d> | 2.578125 | 368 | News Article | Science & Tech. | -2.142747 | 95,585,806 |
Atomic mass constant
In physics and chemistry, the atomic mass constant, mu, is one twelfth of the mass of an unbound atom of carbon-12 at rest and in its ground state. It serves to define the atomic mass unit and is, by definition, equal to 1 u. It is inverse of Avogadro constant (1/NA) when expressed in grams (instead of SI unit kilogram). The CODATA recommended value is 539040(20)×10−27 kg. 1.660
In practice, the atomic mass constant is determined as the ratio of the electron rest mass me to the electron relative atomic mass Ar(e) (that is, the mass of the electron on a scale where 12C = 12). The relative atomic mass of the electron can be measured in cyclotron experiments, while the rest mass of the electron can be derived from other physical constants.
The current uncertainty in the value of the atomic mass constant – one part in 20 million – is almost entirely due to the uncertainty in the value of the Planck constant.
The atomic mass constant can also be expressed as its energy equivalent, that is muc2. The 2010 CODATA recommended values are:
The megaelectronvolt (MeV) is commonly used as an unit of mass in particle physics, and these values are also important for the practical determination of relative atomic masses. Although relative atomic masses are defined for neutral atoms, they are measured (by mass spectrometry) for ions: hence, the measured values must be correct for the mass of the electrons that were removed to form the ions, and also for the mass equivalent of the electron binding energy, Eb/muc2. The total binding energy of the six electrons in a carbon-12 atom is 1030.1089 eV = 1.650 4163×10−16 J: Eb/muc2 = 1.105 8674×10−6, or about one part in 10 million of the mass of the atom.
- IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "atomic mass constant".
- "CODATA Value: atomic mass constant". The NIST Reference on Constants, Units, and Uncertainty. US National Institute of Standards and Technology. June 2015. Retrieved 2015-09-25.
2014 CODATA recommended values
- Mohr, Peter J.; Taylor, Barry N. (1999). "CODATA recommended values of the fundamental physical constants: 1998". Journal of Physical and Chemical Reference Data. 28 (6): 1713–1852. doi:10.1103/RevModPhys.72.351.
- Atomic mass constant energy equivalent National Institute of Standards and Technology
- Mohr, Peter J.; Taylor, Barry N.; Newell, David B. (2011). "CODATA Recommended Values of the Fundamental Physical Constants: 2010". Database developed by J. Baker, M. Douma, and S. Kotochigova. National Institute of Standards and Technology, Gaithersburg, MD 20899.
- Atomic mass constant energy equivalent in MeV National Institute of Standards and Technology
- Mohr, Peter J.; Taylor, Barry N. (2005). "CODATA recommended values of the fundamental physical constants: 2002". Reviews of Modern Physics. 77 (1): 1–107. Bibcode:2005RvMP...77....1M. doi:10.1103/RevModPhys.77.1. | <urn:uuid:d2370588-d044-4b25-9b49-de8b9146a64d> | 3.5625 | 741 | Knowledge Article | Science & Tech. | 62.546956 | 95,585,810 |
Since the 1960s Clean Air Act, and its reinforcement in the 1990s, air toxins that trigger acid rain have been reduced, resulting in positive ecological effects. Now, Northeast forests once scarred by acid rain are mostly green, with red spruce trees thriving.
Scientists have been in the field measuring Kilauea volcano's eruptions 24 hours a day, seven days a week since it first exploded two months ago, trying to discover warning signs for future eruptions.
President Trump's approval of Andrew Wheeler, a former coal lobbyist, as the Environmental Protection Agency's new chief to replace Scott Pruitt has renewed partisan debate about climate change and the environment.
A November ballot initiative is being proposed in Washington State that would require fossil fuel companies to pay carbon fees for their emissions. Supporters say it increases accountability for the companies, opposers say it will increase gas and oil prices.
For the past two years, researchers have been studying Kenya's underground water resource system with the ultimate aim of determining sustainable water practices in a country struggling to meet water demand.
The Colorado River is predicted to suffer water shortages in the coming years that could affect 40 million people. That's why Arizona is working to develop a conservation plan for the river network by the end of the year.
After five years of civil war, opposing factions in South Sudan signed a cease-fire on Wednesday that could eventually resolve the conflict. Some are skeptical if the deal will hold, however, given that previous agreements have collapsed.
Conservation efforts are often portrayed as being in opposition to economic interests. But to most Maine lobstermen environmental sustainability is an economic imperative – and a source of pride.
After near extinction in the 1970s due to famine and disease, African wild dogs have been re-introduced in Gorongosa National Park as part of a carefully planned project to restore the species in a diverse ecosystem where it can thrive.
The United States, Japan, Germany, and others have long used China as a dumping ground for plastic waste, exporting an estimated 116 million tons of waste since 1992. Now, the country's recent ban is serving as a wake-up call for countries to manage waste better.
Electronic waste – while a lucrative business for processing plants – releases harmful lead, mercury, cadmium, and other toxins into the environment. E-waste is a growing problem in Southeast Asia as China cracks down on its recycling and e-waste imports, the world's main dumping ground for e-waste for the past two decades.
Over the next five years, the Environmental Protection Agency will work to remove or control toxic contaminants from campgrounds, mine waste piles, ponds, and rivers.
Deadly wildfires in Portugal killed 106 people in 2017. Now, government officials are focusing on prevention. One part of the solution: hiring dozens of goat herds to eat vegetation that could otherwise be potential kindling for forest fires. | <urn:uuid:7a304f4b-7067-4bd2-9fbe-8f191cc92323> | 2.6875 | 590 | Content Listing | Science & Tech. | 35.054202 | 95,585,817 |
Gravity may have saved the universe from collapsing immediately after the Big Bang by providing stability needed to survive expansion during that period, a new study suggests.
Studies of the Higgs particle discovered at CERN in 2012 and responsible for giving mass to all particles have suggested that the production of Higgs particles during the accelerating expansion of the very early universe (inflation) should have led to instability and collapse.
Scientists have been trying to find out why this did not happen, leading to theories that there must be some new physics that will help explain the origins of the universe that has not yet been discovered.
Physicists from Imperial College London, and the Universities of Copenhagen and Helsinki, described how the spacetime curvature – in effect, gravity – provided the stability needed for the universe to survive expansion in that early period.
Researchers investigated the interaction between the Higgs particles and gravity, taking into account how it would vary with energy.
They show that even a small interaction would have been enough to stabilise the universe against decay.
“The Standard Model of particle physics, which scientists use to explain elementary particles and their interactions, has so far not provided an answer to why the universe did not collapse following the Big Bang,” said Professor Arttu Rajantie, from the Department of Physics at Imperial College London.
“Our research investigates the last unknown parameter in the Standard Model – the interaction between the Higgs particle and gravity.
“This parameter cannot be measured in particle accelerator experiments, but it has a big effect on the Higgs instability during inflation. Even a relatively small value is enough to explain the survival of the universe without any new physics!” Rajantie said.
The team plan to continue their research using cosmological observations to look at this interaction in more detail and explain what effect it would have had on the development of the early universe.
The study was published in the journal Physical Review Letters. | <urn:uuid:9269fdc7-4eba-41ce-8425-4c8ebb35f219> | 3.875 | 397 | News Article | Science & Tech. | 20.641461 | 95,585,818 |
City could know as early as 2020 how high sea level will go in the next century
Miami could know as early as 2020 how high sea levels will rise into the next century, according to a team of researchers including Florida International University scientist Rene Price.
Price is also affiliated with the National Science Foundation's (NSF) Florida Coastal Everglades Long-Term Ecological Research (LTER) site, one of 25 such NSF LTER sites in ecosystems from coral reefs to deserts, mountains to salt marshes around the world.
Scientists conclude that sea level rise is one of the most certain consequences of climate change.
But the speed and long-term height of that rise are unknown. Some researchers believe that sea level rise is accelerating, some suggest the rate is holding steady, while others say it's decelerating.
With long-term data showing that global sea levels are steadily rising at 2.8 millimeters per year, and climate models indicating that the rate could accelerate over time, Price posed a question to colleagues: How soon will Miami residents know what sea levels will be in the year 2100?
"In Miami, we're at the forefront of sea level rise," Price says. "With the uncertainty in what we currently know, I was looking for information that could help us plan better for the long-term."
Price and a team of international researchers set out to answer the question.
They analyzed data from 10 sea level monitoring stations throughout the world.
They looked into the future by analyzing the past.
The researchers examined historical data to identify the timing at which accelerations might first be recognized in a significant manner and extended projections through 2100.
The findings are published in this week's issue of the journal Nature Communications.
"Sea level rise will have major effects on natural and built coastal environments," says David Garrison, program director in NSF's Division of Ocean Sciences, which co-funds the NSF LTER network with NSF's Division of Environmental Biology.
"Being able to detect and predict the pace of sea level rise is critical to being able to adapt to future changes in coastal regions," says Garrison.
Price says the information provided should offer some comfort to those living with this uncertainty.
"Our results show that by 2020 to 2030, we could have some statistical certainty of what the sea level rise situation will look like," she says.
"That means we'll know what to expect and have 70 years to plan. In a subject that has so much uncertainty, this gives us the gift of long-term planning."
Conservative projections suggest that sea level could rise by .3 meters by 2100, but with acceleration, some scientists believe that number will be closer to 1 meter.
"Areas of Miami Beach could experience constant flooding," says Price.
"The Everglades and mangroves may not be able to keep up. Mangroves are very important to South Florida, and their loss would likely mean more land erosion.
"We could see large portions of the Everglades taken over by the ocean. Areas that are freshwater today could become saltwater by 2100."
As cities, including Miami, continue to plan for long-term solutions to sea level rise, Price says she was surprised to discover that in the span of 20 years, scientists would be in a position to predict the long-term situation for Miami and other coastal areas across the planet.
Scientists should continue to crunch the numbers every decade, says Price, creating more certainty in long-term planning--and helping develop solutions for a changing planet.
NSF Long-Term Ecological Research Network: http://www.lternet.edu
NSF Florida Coastal Everglades (FCE) LTER Site: http://www.lternet.edu/sites/fce
NSF Publication: Discoveries in Long-Term Ecological Research: http://www.nsf.gov/pubs/2013/nsf13083/nsf13083.pdf
NSF LTER Discovery Article Series: The Search for White Gold: http://nsf.gov/discoveries/disc_summ.jsp?cntn_id=127580
NSF LTER FCE News: Seagrasses Can Store as Much Carbon as Forests: http://www.nsf.gov/news/news_summ.jsp?org=NSF&cntn_id=124263&preview=false
NSF LTER FCE News: Gulf Oil Spill: NSF Funds Research on Impacts to Florida Everglades: http://www.nsf.gov/news/news_summ.jsp?cntn_id=117430
NSF LTER FCE News: Where Does Charcoal, or Black Carbon, in Soils Go?: http://www.nsf.gov/news/news_summ.jsp?cntn_id=127577
The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2014, its budget is $7.2 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives about 50,000 competitive requests for funding, and makes about 11,500 new funding awards. NSF also awards about $593 million in professional and service contracts yearly.
Cheryl Dybas | Eurek Alert!
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
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Screening Recombinant DNA Libraries
Part of the
Methods in Molecular Biology™
book series (MIMB, volume 235)
A recombinant DNA library typically represents part or all of an organism’s genomic DNA or mRNA (represented as cDNA) cloned into vectors and stored as a collection of thousands of transformants. The construction of a complete library is only half the task; researchers then need to be able to identify the small number of clones bearing the DNA fragment of interest among the numerous transformants within the library. This process is called “screening a library” and it is the molecular equivalent of finding a needle in a haystack. Libraries may be screened by any one of several methods.
KeywordsLibrary Clone Dark Spot Label Probe Wash Solution Multiwell Plate
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
Southern, E. M. (1975) Detection of specific sequences among DNA fragments separated by gel electrohoresis. J. Mol. Biol.
, 503–517.PubMedCrossRefGoogle Scholar
Feinberg, A. P. and Vogelstein, B. (1983) A technique for radiolabeling DNA restriction endonuclease fragments to high specific activity. Anal. Biochem.
, 6–13.PubMedCrossRefGoogle Scholar
Denhardt, D. (1966) A membrane filter technique for the detection of complementary DNA. Biochem. Biophys. Res. Commun.
, 641–646.PubMedCrossRefGoogle Scholar | <urn:uuid:11778745-1766-4200-930f-3a17d900da44> | 2.921875 | 333 | Academic Writing | Science & Tech. | 44.854277 | 95,585,840 |
Species Detail - Greenhouse Slug (Lehmannia valentiana) - Species information displayed is based on the dataset "All Ireland Non-Marine Molluscan Database".
Terrestrial Map - 10kmDistribution of the number of records recorded within each 10km grid square (ITM).
Marine Map - 50kmDistribution of the number of records recorded within each 50km grid square (WGS84).
(A. Férussac, 1822)
18 January (recorded in 2003)
1 December (recorded in 2002)
Conchological Society of Great Britain and Ireland, All Ireland Non-Marine Molluscan Database, National Biodiversity Data Centre, Ireland, Greenhouse Slug (Lehmannia valentiana), accessed 20 July 2018, <https://maps.biodiversityireland.ie/Dataset/1/Species/123889> | <urn:uuid:72b81220-6389-43e5-ab76-51fadfcf9e69> | 2.734375 | 192 | Structured Data | Science & Tech. | 26.458823 | 95,585,849 |
Biological Chaos and Complex Dynamics
- LAST REVIEWED: 06 May 2016
- LAST MODIFIED: 23 May 2012
- DOI: 10.1093/obo/9780199830060-0024
- LAST REVIEWED: 06 May 2016
- LAST MODIFIED: 23 May 2012
- DOI: 10.1093/obo/9780199830060-0024
Classically, chaos is defined as a lack of order; however, in a scientific context it refers to the lack of predictability of a process or sample. Chaos differs from randomness in that chaotic systems are purely deterministic; that is, they are entirely determined by a set of mathematical formulas and initial conditions, with no random elements involved. Particularly intriguing is that chaotic systems are especially sensitive to initial conditions; simulations of a chaotic system initiated at only slightly different states will quickly diverge so that predicting the state of one iteration of the chaotic system from a second is not possible. This lack of predictability is the origin of the term “butterfly effect,” which was made famous by the meteorologist Edward N. Lorenz in his talk “Predictability: Does the Flap of a Butterfly’s Wings in Brazil Set Off a Tornado in Texas?” In addition to chaos, other forms of complex dynamics, such as regular oscillations and quasiperiodic oscillations, are preeminent features of many biological systems. Recognition of these types of dynamics came first from early observations on economically important species, such as fish and small mammals, and soon after from mathematical models that ecologists used to understand the basic processes of population demography. Early evidence for chaos and complex dynamics challenged the classical notion that ecological systems are dominated by equilibrium-based processes (a “natural” or reference state of the system to which it would return if left unperturbed by the external influence of humans, climate, and so on) and raised great skepticism about our ability to accurately predict the fate of populations for conservation and management. Although there is considerable challenge discerning chaos and complex dynamics from noisy equilibrium-based dynamics, the former has come to be accepted as a viable but (in most instances) rare population attribute. The intense study of these subjects during the 1980s and 1990s has given biologists and ecologists an increased awareness of when and where to expect chaos and complex dynamics. Research in the early 2000s has focused less on the identification of these patterns in real data and experiments and more on the reasons why natural systems seem to exhibit more simple and stable dynamics than many models predict.
A number of general overviews have provided a general description of the mathematical phenomena of chaos and complex dynamics and their applications in biological systems. Perhaps the most well-known overview and popular history of chaos is Gleick 2008; however, Strogatz 2000 provides an accessible mathematical introduction to chaos and complex dynamics that is often motivated with examples from the biological sciences. Turchin 2003 provides the most comprehensive overview of chaos and complex dynamics in ecology, combining a mix of models and empirical evidence. Cushing, et al. 2003 demonstrates that the complex dynamics of real populations can be derived by integrating the important biological mechanisms into simple mathematical models. The body of work discussed therein is arguably the best understood of any ecological examples of chaos. Many notable review papers emerged during the 1990s, when the search for chaos and complex dynamics was at the forefront in ecology. Of these, Hastings, et al. 1993 provides a comprehensive review of work describing approaches to detect chaos and complex dynamics in real data. Logan and Allen 1992 and Stone and Ezrati 1996 review mounting evidence for chaos and provide important perspectives on the role of chaos and complex dynamics in ecology. Ferrière and Fox 1995 reviews the role of nonlinearity in models of evolutionary change with specific reference to complex dynamics and chaos.
Cushing, J. M., R. F. Costantino, Brian Dennis, Robert A. Desharnais, and Shandelle M. Henson. 2003. Chaos in ecology. Vol. 1, Experimental nonlinear dynamics. Boston: Academic Press.
This work is a synthesis of a series of experiments and theory that used Tribolium as a model organism to demonstrate chaos. The authors describe experiments and models aimed at understanding chaos and set their model system into the landscape of other important examples.
Ferrière, R., and G. A. Fox. 1995. Chaos and evolution. Trends in Ecology and Evolution 10:480–485.
The authors argue that the nonlinearities commonly describing ecological dynamics may have previously overlooked the importance of understanding changes in gene frequency and long-term fluctuations in selection. They argue that when chaotic processes are at work, evolution may not necessarily be seen as an adaptive process.
Gleick, James. 2008. Chaos: Making a new science. New York: Penguin.
The author gives a thought-provoking introduction to chaos theory and the people who dominated its history. This is perhaps the most popular book ever written on the topic and is easily accessible to all levels of interested readers.
Hastings, Alan, Carole L. Hom, Stephen Ellner, Peter Turchin, and H. Charles J. Godfray. 1993. Chaos in ecology: Is Mother Nature a strange attractor? Annual Review of Ecology and Systematics 24:1–33.
The authors review methods for detecting chaos in natural data with the intent of providing a more solid understanding of nonlinear dynamics for the field of ecology. Available online for purchase or by subscription.
Logan, J. A., and J. C. Allen. 1992. Nonlinear dynamics and chaos in insect populations. Annual Review of Entomology 37:455–477.
The authors review the mounting evidence for complex dynamics and chaos in insect populations. Available online for purchase or by subscription.
Stone, Lewi, and Smadar Ezrati. 1996. Chaos, cycles, and spatiotemporal dynamics in plant ecology. Journal of Ecology 84:279–291.
The authors revisit the idea that chaos and complex dynamics are not important in plant communities by amassing literature on the subject. Available online for purchase or by subscription.
Strogatz, Steven H. 2000. Nonlinear dynamics and chaos: With applications to physics, biology, chemistry, and engineering. Studies in Nonlinearity. Cambridge, MA: Westview.
The author provides an accessible mathematical introduction to chaos and complex dynamics with many biological examples discussed throughout. Elements of equilibrium theory and linearization techniques are well explained with the aid of many helpful graphs and figures.
Turchin, Peter. 2003. Complex population dynamics: A theoretical/empirical synthesis. Princeton, NJ: Princeton Univ. Press.
The author provides the most comprehensive and up-to-date review of the experimental and natural evidence for chaos and complex dynamics and describes the ecologically relevant models.
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- Accounting for Ecological Capital
- Allocation of Reproductive Resources in Plants
- Animals, Functional Morphology of
- Animals, Reproductive Allocation in
- Animals, Thermoregulation in
- Antarctic Environments and Ecology
- Applied Ecology
- Aquatic Conservation
- Aquatic Nutrient Cycling
- Archaea, Ecology of
- Assembly Models
- Bacterial Diversity in Freshwater
- Benthic Ecology
- Biodiversity and Ecosystem Functioning
- Biodiversity Patterns in Agricultural Systms
- Biological Chaos and Complex Dynamics
- Biome, Alpine
- Biome, Boreal
- Biome, Desert
- Biome, Grassland
- Biome, Savanna
- Biome, Tundra
- Biomes, African
- Biomes, East Asian
- Biomes, Mountain
- Biomes, North American
- Biomes, South Asian
- Bryophyte Ecology
- Butterfly Ecology
- Carson, Rachel
- Chemical Ecology
- Classification Analysis
- Coastal Dune Habitats
- Communities and Ecosystems, Indirect Effects in
- Communities, Top-Down and Bottom-Up Regulation of
- Community Concept, The
- Community Ecology
- Community Genetics
- Community Phenology
- Competition and Coexistence in Animal Communities
- Competition in Plant Communities
- Complexity Theory
- Conservation Biology
- Conservation Genetics
- Coral Reefs
- Darwin, Charles
- Dead Wood in Forest Ecosystems
- De-Glaciation, Ecology of
- Disease Ecology
- Drought as a Disturbance in Forests
- Early Explorers, The
- Earth’s Climate, The
- Eco-Evolutionary Dynamics
- Ecological Dynamics in Fragmented Landscapes
- Ecological Informatics
- Ecological Relevance of Speciation
- Ecology, Microbial (Community)
- Ecology of Emerging Zoonotic Viruses
- Ecosystem Engineers
- Ecosystem Multifunctionality
- Ecosystem Services
- Ecosystem Services, Conservation of
- Elton, Charles
- Endophytes, Fungal
- Energy Flow
- Environments, Extreme
- Ethics, Ecological
- Facilitation and the Organization of Communities
- Fern and Lycophyte Ecology
- Fire Ecology
- Food Webs
- Foraging Behavior, Implications of
- Foraging, Optimal
- Forests, Temperate Coniferous
- Forests, Temperate Deciduous
- Freshwater Invertebrate Ecology
- Genetic Considerations in Plant Ecological Restoration
- Genomics, Ecological
- Geographic Range
- Gleason, Henry
- Grazer Ecology
- Greig-Smith, Peter
- Gymnosperm Ecology
- Habitat Selection
- Harper, John L.
- Heavy Metal Tolerance
- Himalaya, Ecology of the
- Host-Parasitoid Interactions
- Human Ecology
- Human Ecology of the Andes
- Hutchinson, G. Evelyn
- Indigenous Ecologies
- Industrial Ecology
- Insect Ecology, Terrestrial
- Introductory Sources
- Invasive Species
- Island Biogeography Theory
- Island Biology
- Kin Selection
- Landscape Dynamics
- Landscape Ecology
- Laws, Ecological
- Legume-Rhizobium Symbiosis, The
- Leopold, Aldo
- Lichen Ecology
- Life History
- Literature, Ecology and
- MacArthur, Robert H.
- Mangrove Zone Ecology
- Marine Fisheries Management
- Mathematical Ecology
- Mating Systems
- Maximum Sustainable Yield
- Metabolic Scaling Theory
- Metacommunity Dynamics
- Metapopulations and Spatial Population Processes
- Microclimate Ecology
- Mutualisms and Symbioses
- Mycorrhizal Ecology
- Natural History Tradition, The
- Networks, Ecological
- Niche Versus Neutral Models of Community Organization
- Nutrient Foraging in Plants
- Odum, Eugene and Howard
- Old Fields
- Ordination Analysis
- Organic Agriculture, Ecology of
- Parental Care, Evolution of
- Patch Dynamics
- Phenotypic Selection
- Philosophy, Ecological
- Phylogenetics and Comparative Methods
- Physiological Ecology of Nutrient Acquisition in Animals
- Physiological Ecology of Photosynthesis
- Physiological Ecology of Water Balance in Terrestrial Anim...
- Plant Disease Epidemiology
- Plant Ecological Responses to Extreme Climatic Events
- Plant-Insect Interactions
- Polar Regions
- Pollination Ecology
- Population Dynamics, Density-Dependence and Single-Species
- Population Dynamics, Methods in
- Population Ecology, Animal
- Population Ecology, Plant
- Population Fluctuations and Cycles
- Population Genetics
- Population Viability Analysis
- Populations and Communities, Dynamics of Age- and Stage-St...
- Predation and Community Organization
- Predator-Prey Interactions
- Reductionism Versus Holism
- Religion and Ecology
- Remote Sensing
- Restoration Ecology
- Ricketts, Edward Flanders Robb
- Seed Ecology
- Serpentine Soils
- Shelford, Victor
- Simulation Modeling
- Soil Biogeochemistry
- Soil Ecology
- Spatial Pattern Analysis
- Spatial Patterns of Species Biodiversity in Terrestrial En...
- Species Extinctions
- Species Responses to Climate Change
- Species-Area Relationships
- Stability and Ecosystem Resilience, A Below-Ground Perspec...
- Stoichiometry, Ecological
- Stream Ecology
- Systems Ecology
- Tansley, Sir Arthur
- Terrestrial Nitrogen Cycle
- Terrestrial Resource Limitation
- Thermal Ecology of Animals
- Tragedy of the Commons
- Trophic Levels
- Vegetation Classification
- Vegetation Mapping
- Weed Ecology
- Whittaker, Robert H.
- Wildlife Ecology | <urn:uuid:2f1f16a8-fb4e-47de-956a-fd98d3b72e2b> | 3.328125 | 2,739 | Truncated | Science & Tech. | 8.678492 | 95,585,857 |
Organic chemistry has always been a vast subject of research among the science enthusiasts. The idea of basic organic chemistry is to propagate the elementary information about the organic compounds that exist around us and provide a solid foundation for the further exploration of organic compounds and the factors that govern the properties of these compounds. The organic compounds from a series, known as homologs series in which the successive compounds contain the same functional groups and differ from one another by a –CH2 group. Alcohol is one of the many functional groups found in organic compounds.In this article, we will learn about alcohol structure, phenol structure, and other structure.
What is Alcohol?
Alcohols are the organic compounds in which a hydrogen atom or an aliphatic carbon is replaced with the hydroxyl group. Thus an alcohol molecule consists of two parts; one containing the alkyl group and the other containing hydroxyl group. They have a sweet odor. They exhibit a unique set of physical and chemical properties. These physical and chemical properties of alcohols are mainly due to the presence of hydroxyl group. The alcohol structure depends on various factors.
Alcohol structure is mainly attributed to the presence of hydroxyl group. In alcohols, the carbon atom of the main chain is bonded to the oxygen atom of the hydroxyl group by a sigma (σ) bond. This sigma bond is formed due to the overlap of an sp3 hybridized orbital of carbon with an sp3 hybridized orbital of oxygen. Due to the repulsion between the unshared electron pairs of oxygen, the bond angle of C-O-H bonds in alcohols is slightly less than the tetrahedral angle (109°-28′).
Phenol structure is mainly attributed to two factors:
- Partial double bond character due to the resonance in the aromatic ring because of conjugated electron pair of oxygen.
- Hybridization of carbon to which oxygen atom of the hydroxyl group is The carbon atom attached to oxygen is sp2 hybridized in phenol.
Hence, C-O bond length in phenol is slightly less than that in methanol.
- An ether molecule has a tetrahedral structure.
- Due to the repulsive interaction between the two bulky (–R) groups, the bond angle (R-O-R) is slightly greater than the tetrahedral angle.
- The C–O bond length in ether is almost the same as in alcohols.
To learn more about alcohol structure, ether structure and phenol structure and other topics of chemistry, register with BYJU’S.
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|Aphis glycines, the soybean aphid|
The Aphididae are a very large insect family in the aphid superfamily (Aphidoidea), of the order Hemiptera. Several thousand species are placed in this family, many of which are well known for being serious plant pests. They are also the family of insects containing most plant virus vectors (around 200 known) with the green peach aphid (Myzus persicae) being one of the most prevalent and indiscriminate carriers.
Aphids originated in the late Cretaceous about (Mya), but the Aphidinae which comprises about half of the 4700 described species and genera of aphids alive today come from their most recent radiation which occurred in the late Tertiary less than 10 Mya.
Members of the Aphididae are soft-bodied, pear-shaped insects called aphids, as are other members of the superfamily Aphidoidea. Most of them have a pair of little tubes, called cornicles, projecting dorsally from the posteriorof their abdomens. The cornicles have been variously interpreted in the past, either as organs of excretion, or for the production of honeydew, but in fact their only confirmed function to date is that they produce fatty alarm pheromones when the insects are attacked by predators.
When wings are present they occur only on particular morphs called "alates", and wingless morphs are said to be "apterous". The forewing (mesothoracic wing) of the alate in the Aphididae has four to six veins attached to a major vein-like structure that has been interpreted as the combined stems of all the other major wing veins. That structure ends in a stigma, a solid spot on the anterior margin of the forewing. The rear (metathoracic) wings have a similar scheme, but simpler in structure, with no stigma The rear wing however, does bear a hamulus, a small hook that, when in flight, engages the claval fold of the forewing, keeping the wing beats in synchrony.
These insects are so small (a few millimeters in length), that winds can transport them for fairly long distances. They are often green, but might be red or brown, as well. They move quite slowly and cannot jump or hop. Aphids excrete a sugary liquid called honeydew, because the plant sap from which they feed contains excess carbohydrates relative to its low protein content. To satisfy their protein needs, they absorb large amounts of sap and excrete the excess carbohydrates. Honeydew is used as food by ants, honeybees, and many other insects.
There are an extremely large number of aphid genera which are dealt with under each subfamily. For which see taxobox.
- Aphis fabae - blackfly, black bean aphid, bean aphid, or beet leaf aphid
- Aphis gossypii - cotton aphid, melon aphid, or melon and cotton aphid
- Beech blight aphid (Grylloprociphilus imbricator)
- Brevicoryne brassicae - cabbage aphid, cabbage aphid, or turnip aphid
- Cinara cupressi - cypress aphid
- Macrosiphum euphorbiae - potato aphid
- Melaphis chinensis - Chinese sumac aphid
- Mindarus harringtoni
- Nasonovia ribisnigri
- Pea aphid (Acyrthosiphon pisum)
- Pemphigus betae - sugarbeet root aphid
- Rose aphid (Macrosiphum rosae)
- Russian wheat aphid (Diuraphis noxia)
- Sipha flava - yellow sugarcane aphid
- Soybean aphid (Aphis glycines)
- Toxoptera citricida - brown citrus aphid, black citrus aphid, or oriental citrus aphid
- Witch-hazel cone gall aphid (Hormaphis hamamelidis)
- Wooly aphids - Subfamily: Eriosomatinae
- Von Dohlen CD, Moran NA (2000) Molecular data support a rapid radiation of aphids in the Cretaceous and multiple origins of host alternation. Biol J Linnean Soc 71: 689–717
- Von Dohlen CD, Rowe CA, Heie OE (2006) A test of morphological hypotheses for tribal and subtribal relationships of Aphidinae (Insecta: Hemiptera: Aphididae) using DNA sequences. Mol Phylo Evol 38: 316–329
- Richards, O. W.; Davies, R.G. (1977). Imms' General Textbook of Entomology: Volume 1: Structure, Physiology and Development Volume 2: Classification and Biology. Berlin: Springer. ISBN 0-412-61390-5.
|Wikimedia Commons has media related to Aphididae.|
- Aphis gossypii, melon or cotton aphid
- Aphis nerii, oleander aphid
- Cerataphis brasiliensis, palm aphid
- Hyadaphis coriandri, corianderaphid
- Longistigma caryae, giant bark aphid
- Myzus persicae, green peach aphid
- Sarucallis kahawaluokalani, crapemyrtle aphid
- Schizaphis graminum, greenbug
- Shivaphis celti, an Asian woolly hackberry aphid
- Sipha flava, yellow sugarcane aphid
- Toxoptera citricida, brown citrus aphid | <urn:uuid:af2de70d-5774-4891-bb77-308a5f639f37> | 3.671875 | 1,250 | Knowledge Article | Science & Tech. | 25.347844 | 95,585,891 |
What is ionization?
Radiation from radioactive substances can knock electrons out of atoms
Atoms become positively charged when losing electrons
How can ionisation in living cell?
Damage/kill the cell
How does an object become irradiated?
If it is exposed to ionizing radiation
Remember that the object does not become radioactive
What is radioactive contamination?
Is unwanted presence of materials containing
radioactive atoms on other materials
How are alpha particles strongly ionising?
Consist of two protons and two neutrons
Relatively large , alpha particles have lots of collisions with atoms
What can alpha particles be stopped by?
With collisions, alpha particles do not penetrate far into thin sheet or paper, human skin or few centimetres of air
What movement of the beta particle?
Fast-moving electrons emitted from the nucleus
How are beta particles less ionizing?
Much smaller and faster than alpha particles
less ionising and penetrate further into material than alpha particles
What are beta particles blocked by?
Thin sheet of aluminium or few metres of air
How are gamma radiation weakly ionising and very penetrating?
They are electromagnetic waves so they travel a long way through material before colliding with atom
What can stop gamma radiation?
Several centimetres of lead/concrete needed to be absorbed
ultimate range in the air | <urn:uuid:8bef4e1d-c772-4dbd-bd07-d049d87d7d2d> | 3.46875 | 278 | Structured Data | Science & Tech. | 23.377777 | 95,585,945 |
By Hannah Hudson
November 2017 – There were cool breezes across the UK on the afternoon of 15 October 1987 – certainly nothing to give cause for alarm. On the evening news, radio and TV forecasts noted slightly stronger winds, but suggested that heavy rain would be the main feature for the upcoming weekend. There was no mention of the gales gathering pace over the English Channel, nor the low atmospheric pressure over the Bay of Biscay. Weather forecaster Michael Fish chuckled as he told BBC viewers, on their way to bed, not to worry – there would be no hurricane tonight.
Technically he was right – there was no hurricane. Instead, southeast England experienced the worst storm to hit in three centuries. Gusting winds of up to 100mph felled around 15 million trees – some of which fell onto roads and railways, causing major transport delays. Others took down electricity and telephone lines, leaving thousands of homes without power for more than 24 hours. Buildings were damaged. Numerous small boats were wrecked or blown away. A Channel ferry was blown ashore near Folkestone. Eighteen people lost their lives.
The incident dramatically highlighted the gaps in our ability to accurately predict the weather, and demonstrated the need for better forecasting. Fast forward 30 years and recent global weather events have shown the demand is greater than ever. So how have things changed?
THE CURRENT ATMOSPHERE
“We’re getting better all the time at predicting the weather,” says Jonathan Dutton, head of aviation business at the UK’s Met Of ce. “Since the Great Storm, the accuracy of three- to ten-day forecasts has increased by about one day per decade, with today’s four-day forecast now as accurate as our one-day forecast 30 years ago.”
One of the key reasons for the improvement is the increasing number – and better quality – of observation sources, which includes satellites, ground-based radiomagnetic detection equipment and networks
of humidity sensors. Nasa’s GOES-16 satellite, for example, which launched in November last year, can scan the Earth ve times faster and with better image resolution than previous satellites, while weather radars can now distinguish between rain, snow, sleet and hail.
Computing has advanced, too. In October last year, the Met Of ce unveiled its new £97m supercomputer, capable of producing the most accurate short-term forecasts scienti cally possible. “Supercomputers allow us to analyse more information, with more accuracy, to produce more relevant results,” says Dutton. “We can also be more precise – coming up with models that operate at increasingly ne scales.” While meteorologists used to divide the globe up into a grid of boxes about 25x25km in size, now they’re down to 10km, and high-resolution models can focus on blocks of 1km.
Supercomputers also allow for better forecasting, says Hannah Christensen, from the National Center
for Atmospheric Research in Boulder, Colorado. “It used to be the case that a forecaster would run a single simulation of the weather to come up with the forecast,” she says. “Now, we run our simulator many times, up
to 50, to get a range of possible outcomes – which is a much more truthful prediction. If you’re only making
a single prediction, you’re being overcon dent in what you’re able to do.
Finally, we have become better at understanding how the atmosphere works, and how thunderstorms or other disturbances evolve. “In order to make a prediction of a thunderstorm, you need accurate estimates of the starting conditions, and a forecast simulator that captures all the important processes,” says Christensen. “Through our research and thanks to better technology, our forecasts are really improving. Plus, we’re now able to produce 3D weather visualisations, which really helps us to wrap our heads around the structure of a storm.”
“Weather is the largest source of pervasive disruption on the planet,” says Alex Rutter, managing director EMEA of The Weather Company, an IBM subsidiary. “Solving the problem of how to extract true meaning and genuinely useful insight from weather, not just gures and stats, is an exciting prospect.”
He points to the 50 million people worldwide who suffer from allergies – 88 per cent of whom are able to correlate changes in their symptoms with changes in the weather. “Using weather analytics, we can help pharmaceutical companies and healthcare providers alert patients to developing
weather conditions that could initiate or intensify allergic episodes,” he says. “This gives people a chance to use their medication pre-emptively to avoid symptoms before they occur.” The Weather Company also works in developing countries to track patterns between infectious disease outbreaks and severe weather events. “Monsoons see an increase in water-borne and vector-borne diseases, such as malaria and cholera, while rainfall, temperature and humidity can aid in the development of the primary mosquito that carries diseases such as dengue and Zika,” says Rutter. “We share this data with the life sciences industry, vaccine companies and associations that specialise in infectious disease control.”
Insurance companies, too, are using weather data in clever ways. US-based Weather Analytics creates risk-assessment products from predictive weather models based on atmospheric data. “The weather impacts everything – from underwriting property and insuring against rainfall, to forecasting crop yields and planning exercises for national security,” says Cyrena-Marie Arnold, the company’s senior director of product sciences. “Our expertise comes in combining multiple sources of data to create genuinely useful information for our customers.” In the US, insurers pay about $2bn each year in compensation for vehicles damaged by hail. “We can provide hyper-local forecast information to customers to help them avoid this,” says Arnold. “People can
request notifications when it looks like there’s a chance of hail in their area. We then send them an email to say, ‘You may want to put your car in the garage tomorrow’. You don’t have to go out and look for the forecast – it comes to you.” Weather forecasts have long been helpful to retailers, and now that’s even more the case. “Combining weather information with human emotion can give retailers the tools they need to personalise their services to an incredible degree,” says Rutter. “On a cloudy, rainy day, data shows customers will spend about 30 per cent more in a store, for example, while the temperature can also have an impact. “We have clients who set up alerts if there will be a shift of three or more degrees after a steady period as they know this will trigger certain buying behaviours, and they want to be ready to adjust stock or staffing levels. This means businesses are running in a predictive, incontrol manner, not constantly reacting to events outside their control.”
Planalytics, a weather analytics company with offices in Pennsylvania and London, converts weather information into useful business insights. One client, Subway, was able to work out why one region in the US had not performed well during a recent campaign that had increased sales everywhere else in the country. “It turned out that this region experienced unusually rainy weather, which kept customers from visiting their restaurants,” says Planalytics’ VP marketing, David Frieberg, “Companies that don’t consider weather data are ignoring the biases that are embedded in their past performance,” he adds. “Since the prior year’s sales are commonly used as a basis for next year’s plan, businesses essentially end up planning for the same weather conditions to occur again and they rarely do.” Startups have also spotted the opportunities swirling around weather analysis. Forecasting company Climendo tracks the historical accuracy of various forecasters for specific locations, compares them, and combines the best ones in a single app. It recently launched a new standalone app, Climendo 71%, for swimmers, surfers, anglers, kayakers and anyone who spends time on open water. Surfers can set personalised alerts for when their favourite surf spots are optimal, while sailors receive lightning warnings and data on currents. Anglers, meanwhile, can gather information on when fish are most likely to be active.
WINDS OF CHANGE
So what comes next? “We’re in the middle of this big revolution in how we use weather,” says Bill Gail, chief technology officer at Global Weather Corporation (GWC) in Colorado. “In a decade, we won’t have to check a weather app – we’ll have devices and apps already using weather to help us.” He points to a few examples: “Thermostats will consider weather information to turn your home heater up and down, anticipating changes in the weather to avoid wasting energy. Calendar apps will advise against scheduling outdoor activities when rain is expected. And your lawn irrigation system will skip a watering cycle if rain is anticipated the following day.” GWC is currently working on a joined-up solution to alert drivers in real time to where roads may be treacherous due to poor weather in the US, Europe and China. In the US, more people are killed in weather-related vehicle accidents than large-scale weather disasters (around 5,900 people die every year in these accidents, while the ten-year average combined number of deaths each year from flooding, lightning, tornadoes, hurricanes and heat is 375). Weather data will be fed to connected cars, so drivers will receive alerts if dangerous conditions are on the horizon. “Your satnav will automatically include forecasts when it advises you to take a particular route,” explains Gail. Meanwhile, Boston startup, ClimaCell is concentrating on hyper-local, real-time weather reporting. It claims to be able to forecast the weather with pinpoint accuracy –
even down to tracking the intensity of rainfall on one street versus another in the same neighbourhood. Developed by Israeli air force veteran Shimon Elkabetz, ClimaCell works by combining meteorological signals from wireless and communications networks with traditional sources such as radar and satellites. “If you know what the signal should look like without weather interference and you know how each weather phenomenon affects the signal, then you can retrieve the weather phenomenon from the interference,” explains Elkabetz. The result is minute- by-minute, street level weather data, for historical, real-time, and short-term prediction (within six hours of the event).
Elkabetz wants ClimaCell to be used by everyone from developing countries to private companies, such as airlines. “Because we’re very good at measuring intensity and classifying type of precipitation, we’re also well equipped to support the ‘new economy’, companies such as Uber and Lyft, and new transportation types such as drones and autonomous cars,” he adds.
The future of forecasting will also see a much increased role for social media. “Citizen science is continuing to grow – especially when it comes to weather,” explains Christensen. “Everyone with a smartphone has this incredibly powerful computer in their pocket, capable of recording all sorts of useful information. We already share our location with Google, – why not incorporate barometer readings? There’s huge potential.”
“We have 20 million active mobile users checking the forecast multiple times a day,” says Rutter. (TWC is the default weather forecast for Yahoo, iPhone and Snapchat.) “This means we can map over one billion locations every week – gaining unique insight into customer journeys that map back to real-world locations. We can also ask users to verify the accuracy of our forecasts, by simply asking, ‘Is it raining in your area?’ and get immediate feedback and adjust our forecasts, if necessary.”
Machine learning is another tool shaping the landscape. “We’re only just beginning to think about these kinds of computational techniques in atmospheric research,” says Christensen. “It takes a huge amount of time to analyse all the data we collect – machine learning helps us do it faster and better. We feed in the data and the algorithm looks for the patterns we might not notice otherwise.”
So does this mean the end for weathermen and women? “There will always be a role for people,” says Christensen. “You still need someone to look at what the machine is telling you and to work out if it’s sensible.”
THE FORECAST FOR FORECASTS
So will we ever be able to perfectly predict the weather? “In a word… no,” says Dutton. “While, statistically, our forecasting models have improved, there’s a fundamental predictability limit in the atmosphere. Accurate forecasts rely on having a good understanding of what the atmosphere is doing at the present time, but the atmosphere is inherently chaotic. No matter how good our technology, we’ll never be able to measure the precise position of every air particle or the temperature at every location in the world.” “If we overemphasise how accurate we can be – and then get it wrong – that’s doubly annoying for people,” says Christensen. “Thunderstorms are notoriously hard to pinpoint. If we say there’ll be a big storm over Oxford at X-time, and then it actually passes to the south – the people in Oxford will be upset because the forecast is wrong, and so will the people in the south!” “The way we communicate is an important part of the value of forecasting,” adds Dutton. “As forecast skill develops, so does the need to use language that’s relevant and meaningful to the user. This may be increasingly in the language of risk and focused on the impact.” It seems that, instead of expecting a definitive forecast on the ten o’clock news, we should just simply stay tuned. | <urn:uuid:e036d9b0-c14c-4867-ad01-f24a1ad68e62> | 3.125 | 2,949 | Truncated | Science & Tech. | 37.564529 | 95,585,963 |
by MacGregor Campbell
Publisher: Annenberg Foundation 2017
Number of pages: 441
Mathematics Illuminated is a thirteen-part series for adult learners and high school teachers. The series explores major themes in the field of mathematics, from humankind's earliest study of prime numbers, to the cutting-edge mathematics used to reveal the shape of the universe.
Home page url
Download or read it online for free here:
(multiple PDF files)
by George Howe - Van Nostrand
Mathematics, from algebra through calculus, has been treated in such a manner as to be clear to anyone. Men who wish to study a part of mathematics which they have not hitherto had will find this manual just the book for which they have been looking.
by Yan Min Choo
Includes 300 exercises and all 2006-2015 A-level exam questions -- all worked solutions included. Brief contents: I. Functions and Graphs. II. Sequences and Series. III. Vectors IV. Complex Numbers. V. Calculus. VI. Probability and Statistics.
by Walter E. Wynne, William Spraragen - Van Nostrand
The authors endeavored to supply a handy means of reference to theoretical and applied mathematics used in engineering, and while the first aim has been to make this a mathematical handbook, it also includes the underlying engineering applications.
This book is about the topic of mathematical analysis, particularly in the field of engineering. This will build on topics covered in Probability, Algebra, Linear Algebra, Calculus, Ordinary Differential Equations, and others. | <urn:uuid:4c15a8c5-736b-49fd-9a31-c4125de58ff9> | 3.484375 | 327 | Product Page | Science & Tech. | 44.620394 | 95,585,985 |
NASA and NOAA satellites continue to keep a close eye on the remnants of Tropical Storm Dorian as they make their way through the eastern Caribbean Sea.
NOAA's GOES-13 satellite captured this image of Dorian's remnants (far right) located north of Puerto Rico on July 29 at 10:45 a.m. EDT.
Credit: NASA GOES Project
On Saturday, July 27 at 11 a.m. EDT, Dorian was still a tropical storm, but that didn't last. Dorian was near 18.5N and 52.1W, about 720 miles (1,160 km) east of the Northern Leeward Islands. Dorian's maximum sustained winds were near 40 mph (65 kph) and it was moving to the west at 23 mph (37 kph).
By July 28, Dorian weakened to a remnant low pressure area. It was producing showers and thunderstorms that extended a few hundred miles northeast of the Northern Leeward Islands. Dorian's remnants passed north of the Leeward Islands on July 28.
On Monday, July 29, remnants of Doran and a trough (elongated area) of low pressure were generating disorganized clouds and thunderstorms a couple of hundred miles north of Puerto Rico. Those clouds were seen by NOAA's GOES-13 satellite. The GOES-13 satellite image captured on July 29 at 14:45 UTC (10:45 a.m. EDT) shows that Dorian seems to have regained a more rounded appearance. However, the National Hurricane Center noted that the disturbance still does not appear to have a closed low-level circulation and surface pressures remain high across the area. If pressure drops, it would be a sign that the low pressure area is consolidating, but that was not occurring during the morning of July 29.
GOES satellites are managed and operated by NOAA, and the GOES image was created by NASA's GOES Project at the NASA Goddard Space Flight Center in Greenbelt, Md.Environmental conditions are expected to be only marginally conducive for regeneration to occur, and the National Hurricane Center gives Dorian's remnants a medium chance, about 40 percent of becoming a tropical cyclone again. The remnant low is moving to the west and is expected to move to the west-northwest in the next two days. As it continues moving it is expected to move across the Turks and Caicos Islands and the Bahamas on Tuesday and Wednesday, July 30 and 31.
Rob Gutro | EurekAlert!
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:34864af7-eb8d-44fa-a316-ff5c866616c7> | 2.921875 | 1,139 | Content Listing | Science & Tech. | 51.265269 | 95,586,027 |
Two potentially habitable "super-Earths" orbit a star just 12 light years away that is our nearest sun-like neighbour, scientists have discovered.
The worlds at the edges of Tau Ceti's "habitable zone" belong to a solar system of four rocky planets similar in size to Earth.
British-led astronomers speculate that the system might be a potential candidate for future interstellar colonisation.
But life on the new outposts may be far from peaceful. There is evidence of a massive debris disc circling the star, increasing the chances of the planets being pounded by asteroids and comets.
A key aspect of the discovery was the detection of exoplanets with masses as low as 1.7 times the Earth's, making them the smallest worlds ever spotted around a sun-like star.
The scientists used the "wobble" method of planet finding that measures the influence of gravitational interaction on a star.
As a planet orbits, it causes its parent star to wobble by a tiny degree. Astronomers can see the signature of this effect in the star's light.
Lead researcher Dr Fabo Feng, from the University of Hertfordshire, said: "We're getting tantalisingly close to observing the correct limits required for detecting Earth-like planets.
"Our detection of such weak wobbles is a milestone in the search for Earth analogues and the understanding of the Earth's habitability through comparison with these."
Sun-like stars hold out the best hope of finding planets beyond the solar system that host life. Tau Ceti, a favourite destination of science fiction writers, is very similar to the sun both in size and brightness.
Like the sun, it has a "habitable zone", a narrow region around it where conditions are favourable for Earth-like life.
Within the habitable, or "Goldilocks" zone, temperatures are not too hot or too cold but just right for surface water to exist as a liquid. A habitable zone planet could have oceans, lakes and rivers.
Space tourism: 10 ways you can leave planet Earth
Neither of Tau Ceti's "super-Earths" lie in the centre of its habitable zone. One orbits on the inner border and the other on the outer. The Earth is situated halfway between the middle of the sun's habitable zone and its inner boundary.
The astronomers analysed starlight wavelength data obtained from the European Southern Observatory in Chile and the Keck observatory on Mauna Kea, Hawaii. Their findings are to be published in the Astronomical Journal.
Co-author Dr Mikko Tuomi, also from the University of Hertfordshire, said improved techniques were making it easier to distinguish between light signals caused by the presence of planets and stellar activity.
Two Tau Ceti signals previously identified in 2013 were now known not to have a planetary origin.
"But no matter how we look at the star, there seems to be at least four rocky planets orbiting it," Dr Tuomi said.
"We're slowly learning to tell the difference between wobbles caused by planets and those caused by stellar active surface.
"This enabled us to verify the existence of the two outer, potentially habitable, planets in the system."
Life on the Solar System | <urn:uuid:2df34d44-a98e-4ef7-87c5-beec6b8f00c5> | 3.40625 | 664 | News Article | Science & Tech. | 43.027119 | 95,586,031 |
(Phys.org)—Dark energy is an unknown form of energy that is proposed to drive the accelerated expansion of the universe. A new study by University of Georgia professor Edward Kipreos suggests that changes in how people think about time dilation—the slowing of time predicted by Albert Einstein—can provide an alternate explanation of dark energy.
In the recent Hollywood film "Interstellar," a team of scientists travel through a wormhole in space to access planets with promising conditions to sustain life on Earth. One of the issues the team must grapple with is time dilation: each hour spent collecting data on a given planet is equal to seven years on Earth.
Einstein's general theory of relativity indicates that time dilation in response to gravity is directional in that an object in high gravity will have slower time than an object in low gravity. In contrast, Einstein's theory of special relativity describes reciprocal time dilation between two moving objects, such that both moving objects' times appear to be slowed down relative to each other.
The new paper makes the case that instead of being reciprocal, time dilation in response to movement is directional, with only the moving object undergoing time dilation.
The study, "Implication of an Absolute Simultaneity Theory for Cosmology and Universe Acceleration," was published Dec. 23 in the journal PLOS ONE.
A molecular geneticist whose lab works on cell cycle regulation, Kipreos became interested in cosmology and the theory of special relativity several years ago. He says the phenomenon can be easily understood in the context of how Global Positioning System satellites work.
"The satellites, which travel in free-fall reference frames, are moving fast enough, in relation to the Earth, that you have to correct for their time being slowed down, based on their speed," he said. "If we didn't correct for that, then the satellites' GPS measurement would be off by a factor of two kilometers per day."
This simple example—GPS satellites sending out the time, which is then detected back on Earth, where the distance between the two is measured—is based on the theory of special relativity and the Lorentz Transformation, a mathematical map that describes how measurements of space and time by two observers are related.
"Special relativity is supposed to be reciprocal, where both parties will experience the same time dilation, but all the examples that we have right now can be interpreted as directional time dilation," Kipreos said. "If you look at the GPS satellites, the satellite time is slowing down, but according to the GPS satellites, our time is not slowing down—which would occur if it were reciprocal. Instead, our time is going faster relative to the satellites, and we know that because of constant communication with the satellites."
An alternative theory, the Absolute Lorentz Transformation, describes directional time dilation. Kipreos found that this theory is compatible with available evidence if the "preferred reference frame" for the theory, relative to which directional time dilation occurs, is linked to centers of gravitational mass. Near the Earth, the preferred reference frame would be the "Earth-centered non-rotating inertial reference frame," which is currently used to calculate the time dilation of GPS satellites.
"A strict application of the Absolute Lorentz Transformation to cosmological data has significant implications for the universe and the existence of dark energy," Kipreos said.
As the universe gets larger, cosmological objects, such as galaxies, move more rapidly away from each other in a process known as Hubble expansion. The Absolute Lorentz Transformation indicates that increased velocities induce directional time dilation. Applying this to the increased velocities associated with Hubble expansion in the present universe suggests a scenario in which the present experiences time dilation relative to the past. The passage of time would therefore be slower in the present and faster in the past.
Supernovas that explode with the same intensity are used as "standard candles" to measure cosmological distances based on how bright they appear. Supernovas that are relatively close to the Earth line up on a plot of distance (based on the redshift of light) and brightness. However, in 1998 and 1999, the observation that supernovas at greater distances are fainter than would be expected provided evidence that the rate of universe expansion has accelerated recently.
"The accelerated expansion of the universe has been attributed to the effects of dark energy," Kipreos said. "However, there is no understanding of what dark energy is or why it has manifested only recently.
"The predicted effects of time being faster in the past would have the effect of making the plot of supernovas become linear at all distances, which would imply that there is no acceleration in the expansion of the universe. In this scenario there would be no necessity to invoke the existence of dark energy."
Explore further: Experiment with speeding ions verifies relativistic time dilation to new level of precision
Kipreos ET (2014) "Implications of an Absolute Simultaneity Theory for Cosmology and Universe Acceleration." PLoS ONE 9(12): e115550. DOI: 10.1371/journal.pone.0115550 (PDF) | <urn:uuid:2ddcd9b2-fb52-49b4-8bff-0920893ebea8> | 3.765625 | 1,075 | News Article | Science & Tech. | 25.616197 | 95,586,055 |
1 Ecology and ecosystems.
1.2 Distribution and abundance.
1.2.1 Unit stocks.
1.2.2 Spacing of organisms.
1.3 Population growth and regulation.
1.3.1 Population growth.
1.3.2 Population regulation.
1.3.3 Life history patterns.
1.4 Marine ecosystems.
1.4.1 Coastal waters.
1.4.2 Coral reefs and lagoons.
1.4.3 Continental shelves and the open sea.
1.5 Human impacts on marine ecosystems.
1.5.1 Habitat modification and loss.
1.5.2 Eutrophication, siltation and heat.
1.5.3 Petroleum, toxic chemicals and solid waste.
1.5.4 Species invasions, introductions, and translocations.
1.5.5 Climate change - the greenhouse effect and global warming.
1.5.6 Ozone depletion.
1.5.7 Assessing and minimizing environmental impacts.
1.6 Photosynthetic marine organisms.
1.6.1 Macroalgae - seaweed.
1.6.2 Microalgae - phytoplankton.
1.6.3 Harmful algal blooms.
1.7 The flow of energy and material.
1.7.2 Daily migrations and the seasonal distribution of plankton.
1.7.3 Food relationships, trophic levels and foodwebs.
1.8 Productivity and fisheries.
1.8.1 Primary productivity and yield.
1.8.2 Productivity from fisheries and aquaculture.
2 Exploited species.
Bivalves - clams and cockles.
Gastropods - sea snails.
Cephalopods - squids and octopuses.
Penaeids and carideans - prawns and shrimps.
Nephropidae - clawed lobsters.
Palinuridae - slipper and spiny lobsters.
2.2.3 Other invertebrates.
Holothurians - sea cucumbers.
Echinoids - sea urchins.
2.3.1 Demersal fishes of cooler waters - cods, hakes and haddocks.
2.3.2 Demersal and reef fishes of warmer waters.
2.3.3 Coastal pelagic fishes - clupeoids.
2.3.4 Offshore pelagic fishes - tunas and sharks.
2.3.5 Management measures.
3 Fishing and fishers.
3.2 Fishing gear and methods.
3.2.1 Gleaning, spears and traps.
3.2.2 Hooks and lines.
3.2.3 Stationary nets.
3.2.4 Towed nets and dredges.
3.3.1 Fishing for food.
3.3.2 Fishing for income.
3.3.3 Fishing for recreation.
3.4 Effects of fishing.
3.4.1 Effects on target species.
3.4.2 Effects on non-target species.
3.4.3 Effects on the environment and ecosystems.
4 Stock structure and abundance.
4.2 Structure and abundance.
4.2.1 Relative abundance.
4.2.2 Sampling surveys.
4.2.3 Mark-recapture methods.
4.2.4 Depletion methods.
4.3 Factors that increase biomass.
4.3.1 Size and growth.
4.3.2 Growth from length-frequency data.
4.3.3 Growth from tagging information.
4.3.4 Growth from hard-part analyses.
4.4 Factors that decrease biomass.
4.4.1 Age-based catch curves.
4.4.2 Length-based catch curves.
4.4.3 Mortality from mark-recapture data.
4.4.4 Natural mortality.
5 Stock assessment.
5.2 Stock abundance and catches - dynamic production models.
5.2.1 Equilibrium models.
5.2.2 Non-equilibrium models.
5.2.3 Multispecies applications.
5.2.4 Potential yield - rough estimators.
5.3 Including growth and mortality.
5.3.1 The effects of growth and mortality on biomass.
5.3.2 The effects of fishing mortality on a single cohort.
5.4 Including different year classes; age-structured models.
5.4.1 Virtual population analysis.
5.4.2 The classical yield per recruit model.
5.4.3 The Thompson and Bell model.
5.5 Simulation and ecosystem models.
5.5.1 A biomass dynamic simulation model.
5.5.2 An age-structured simulation model.
5.5.3 Ecosystem models.
5.5.4 Risk assessment.
6 Fisheries management.
6.2 The need for fisheries management.
6.2.1 Biological overfishing.
6.2.2 Economic overfishing.
6.3 Managers and stakeholders.
6.3.1 Fisheries management authorities.
6.3.2 Co-management in commercial fisheries.
6.3.3 Community-based fisheries management.
6.4 The management process.
6.4.1 Management policies and objectives.
6.4.3 Reference points and indicators.
6.4.4 Management plans.
6.5 Management actions.
6.5.1 Input controls (on fishing and fishing effort).
Limiting the number of fishing units.
Limiting the efficiency and types of fishing gear.
Minimum mesh sizes and escape gaps.
6.5.2 Output controls (on the catch).
Rejection of females or gravid females.
6.5.3 Controls to protect the ecosystem.
Closures as fisheries management tools.
6.5.4 Compliance and enforcement.
1. Fisheries symbols and formulae.
2. Standard deviation and confidence limits.
3. Correlation and regression.
4. Least squares.
5. Collection of length-frequency data.
6. Bhattacharya plots.
7. Statistical tables.
Glossary of terms.
"A very up-to-date and substantially improved second edition of this important book. It now incorporates a significant focus in ecosystem management." (Ausmarine)
|Answers to Exercises in the Book|
This file is a PDF. If your computer is not capable of opening PDF files, you can download Acrobat Reader here.
|Black and White Photographs||Download|
- Fully updated and expanded new edition of major text
- New information on analytical tools in use in fisheries, ecology and aquatic sciences areas
- New chapter on environmental influences on ecology and the aquatic environment | <urn:uuid:a9e9903d-834b-415c-a49d-5246bdd2c44f> | 3.703125 | 1,482 | Truncated | Science & Tech. | 80.429153 | 95,586,062 |
If a method is overridden but you use a polymorphic (supertype)
reference to refer to the subtype object with the overriding method, the compiler assumes you�re calling the supertype version of the method. If the supertype version
declares a checked exception, but the overriding subtype method does not, the compiler
still thinks you are calling a method that declares an exception (more in Chapter 5).
Let�s take a look at an example:
Can anyone please explain why did a.eat(), gave error, as it sentence tells the complier treats as if you were calling the superclass method.
"a" is a Animal referance type. Hence if you call any method using referance "a" compiler will assume you are calling a method in an Animal Object. Now because eat() method in Animal Object throws an Exception so we need to handle or declare this exception in our main method. Compiler has no knowledge that "a" actually referances a Dog2 Object.
Which method to call is determined at run time based on object type rather than reference type.
And you must be aware that we can only call overrriden methods from sub class using reference of super class. This is quite logical because compiler do not know at compile time what object is being referenced by super class reference. So at compile time it assumes you are calling the method of super class using super class reference(irrespective of object type) and hence it gives compile time error.
Hope this helps.
Sanket is right. That 'a' refer to the supertype at the compilation time , so when you say a.eat() its consider the method declare in Supertype.
Becouse of declaration of Checked Exception for method eat() in superType, You have to catch the Exception or make the Main() method declare to be thrown
Compile time error need to solve first to make the code able to Run and then only it can be participate in Polymorphisam.
Thanks & Regards
But i have heard that the overriden methods throws unchecked exceptions i.e runtime not the checked exceptions.
Can you little bit elaborate and explain ...
I assume, you made a typo mistake here and what you wanted to say is "if super class throws the checked excpetion, then sub class should also throw the exception"
Yes, this is correct.
The overriden method in the subclass can only throw a subset of the checked exception classes(including their subclasses) thrown by the inherited method in the superclass. This means that an overriding method cannot allow more checked exceptions in its throws clause than the inherited method does.
Allowing more checked exceptions in the overriding method would create problems for clients who already deal with the exceptions specified in the inherited method. Such clients would be ill prepared if an object of the subclass (under the guise of polymorphism) threw a checked exception they were not prepared for.
I hope I have not confused you more#
To summarize, if the super class method throws any checked exception then coresponding sub class method can only throw following type of exceptions:
1. Do not throw any exception
2. Throws all exceptions which are thrown by super class method
3. Throws any exceptions which are sub type of any exceptions thrown by super class method
4. Any run time exception
In all these cases, the code to call this method must be enclosed by try/catch with catch block for all the checked exceptions thrown by super class method.
Just learned a new internet acronym! HTH
These are the worst of times and these are the best of times. And this is the best tiny ad:
Rocket Oven Kickstarter - from the trailbosshttps://coderanch.com/t/695773/Rocket-Oven-Kickstarter-trailboss | <urn:uuid:deffcaec-8b70-4bfd-bf38-6234c4c43b69> | 3.125 | 790 | Comment Section | Software Dev. | 46.119508 | 95,586,081 |
Now, the global status of large sharks has been assessed by the World Conservation Union (IUCN), which is widely recognized as the most comprehensive, scientific-based information source on the threat status of plants and animals.
“As a result of high and mostly unrestricted fishing pressure, many sharks are now considered to be at risk of extinction,” explained Julia Baum, a member of the IUCN’s Shark Specialist Group who will be speaking at the American Association for the Advancement of Science (AAAS) Annual Conference in Boston, which runs from February 14 to 18. She will outline management measures required to conserve sharks at an afternoon press conference on February 17.
“Of particular concern is the scalloped hammerhead shark, an iconic coastal species, which will be listed on the 2008 IUCN Red List as globally ‘endangered’ due to overfishing and high demand for its valuable fins in the shark fin trade,” added Baum, who is an NSERC Postdoctoral Fellow at Scripps Institution of Oceanography.
Baum pointed out that fishing for sharks in international waters is unrestricted, and she supports a recently adopted United Nations resolution calling for immediate shark catch limits as well as a meaningful ban on shark finning (the practice of removing only a shark’s fins and dumping the still live but now helpless shark into the ocean to die).
Research at Dalhousie University over the past five years, conducted by Baum and the late Ransom Myers, demonstrated the magnitude of shark declines in the northwest Atlantic Ocean. All species the team looked at had declined by over 50 per cent since the early 1970s. For many large coastal shark species, the declines were much greater: tiger, scalloped hammerhead, bull and dusky shark populations have all plummeted by more than 95 per cent.
Doré Dunne | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
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Just by picking up the phone, Nobel Laureate and nanotube pioneer Richard Smalley convinced University of Pittsburgh R.K. Mellon Professor of Chemistry and Physics John T. Yates Jr. to enter the field of nanotube surface chemistry. "Rick Smalley's phone call resulted in six years of exciting work," says Yates, who will present highlights of research done at Pitt during a Presidential Event honoring Smalley Sept. 11 at the 232nd American Chemical Society (ACS) National Meeting in San Francisco, Calif.
In collaboration with J. Karl Johnson, who is the William Kepler Whiteford Professor of Chemical Engineering at Pitt, Yates has extensively investigated the use of single-walled carbon nanotubes (SWNTs) as tiny test tubes. SWNTs are cylindrical molecules with a diameter equivalent to about three atoms. The tube walls are made of a single curved sheet of carbon atoms. Experimenting at such a small scale presents many challenges, but offers big rewards: "Doing chemistry inside of nanoscale test tubes allows one to probe the role of extreme molecular confinement on chemical behavior," says Yates, who also directs Pitt's University Surface Science Center.
In the mid-1990s, Smalley recognized that SWNTs would likely be excellent adsorbents because of the enhanced attractive forces expected for molecules located inside the nanotubes. Yates has developed novel methods to measure the relative number of inside and outside molecules attracted to the nanotubes, while Johnson checks experimental results and provides more details through theoretical molecular modeling than could be provided by experiments alone.
Yates and Johnson, along with their students and postdoctoral fellows, obtained a striking result for water molecules confined inside SWNTs, as reported in a recent paper in the Journal of the American Chemical Society. The water molecules inside nanotubes bond together into rings made of seven water molecules. Yates and Johnson, who also are researchers in Pitt's Gertrude E. and John M. Petersen Institute of NanoScience and Engineering, found that these rings stack like donuts along the nanotube. The rings themselves are bound together by a new type of hydrogen bond that is highly strained compared to the hydrogen bonds within each molecular "donut."
The researchers first detected this novel hydrogen bond experimentally by its unusual singular vibrational frequency and later deduced its character by modeling. "The behavior of water as a solvent inside of nanotubes will probably differ strongly from its behavior in ordinary water based on the donut configuration and the new kind of hydrogen bond discovered in this work," says Yates.
In another development, research showed that reactive molecules confined inside nanotubes are well shielded by the nanotube walls from reacting with active chemical species like atomic hydrogen, one of the most aggressive chemical reactants in the chemist's toolbox. The work suggests that chemists could keep certain molecules from reacting by storing them inside nanotubes, while molecules outside the tube are free to react. "This could provide a new tool for focusing reactive chemistry in the laboratory to select one molecule and exclude another one, tucked away inside of a nanotube," Yates says.
The researchers' pioneering work could lead to future SWNT-based technologies such as time-release medications and highly efficient gas masks to decontaminate toxic gases. In addition, their research promises to yield new insights into basic chemistry. "Confining matter inside of nanotubes could lead to a range of new chemical and physical properties for the confined molecules, allowing chemists a higher degree of control of molecular behavior," says Yates.
Karen Hoffmann | EurekAlert!
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...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
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Beetles comprise almost 40% of described insects and 25% of all known animal life-forms. There are about 30,000 beetles known as scarabs or scarab beetles in the family Scarabaeidae. They make up about 10% of all known beetles. You may be very familiar with scarab beetles without even being aware that that is what they are – they are as close as the nearest Japanese Beetle or June Bug (beetle).
Scarabs are generally oval-shaped and stout. The smallest are about .08 inches and the largest (Hercules beetles) can reach 6.7 inches. Most scarabs are black or brown, but many, especially tropical species, have bright colors and intricate patterns. They have distinctive, clubbed antennae composed of plates called lamellae that can be compressed into a ball or fanned out like leaves to sense odors (see photo). Their diet is extremely varied and includes plant material, fungi, fruit, carrion, insects and even the slime left by snails.
One fruit- and flower-eating species is the Emerald Euphoria beetle, Euphoria fulgida (pictured). It is usually bright green or bluish. Emerald Euphoria beetles belong to the subfamily Cetoniiae, the flower or fruit chafers. One of its most distinctive characteristics is its ability to fly (using its second pair of wings) while its first pair (the hardened, colorful elytra) remain closed — most beetles open and extend their elytra during flight.
Unlike most scarabs, Emerald Euphorias are diurnal, making it possible to see this species visiting flowers in order to consume nectar, pollen and petals. (Thanks to Richard Wyatt for photo op.)
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Thanks to a sharp-eyed Naturally Curious blog reader, a recently mis-identified active winter insect can be correctly identified. What I referred to as a “snow scorpionfly” last week was, in fact, a type of crane fly that, as an adult, has no wings. Like snow scorpionflies, these wingless snow-walking crane flies appear on top of the snow on warm winter days. These two kinds of insects are also very similar in shape and size, but, unlike snow scorpionflies, this group of crane flies have what are called halteres, knobbed filaments which act as balancing organs (see photo).
Scorpion snowflies, despite their name, are not true flies in the order Diptera. Crane flies are. Most species of true flies have one pair of wings, instead of the usual two that winged insects have, as well as halters, which take the place of hind wings and vibrate during flight. While wingless snow-walking crane flies lack a pair of wings, they do possess halteres, which are the key to distinguishing between a wingless snow-walking crane fly and a snow scorpionfly, which lacks them! (Thanks to Jay Lehtinen for photo I.D.)
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button. | <urn:uuid:f691a90f-e246-48d5-b300-92289cd93c3d> | 3.8125 | 713 | Personal Blog | Science & Tech. | 51.03839 | 95,586,146 |
The Study of Fast Reactions by the Stopped Flow Method
The mechanisms involved in protein reactions may be elucidated by investigating the reaction kinetics. There are two investigative approaches in ascertaining the combination of elementary steps which constitute these mechanisms:(1) steady state kinetics permits analysis of the overall reaction in which protein substrates are converted into products without examining the protein molecule itself; and (2) transient kinetics allows the direct measurement of each component in the overall reaction. In this latter case, attention is focused on changes occurring in the molecule upon binding to another protein whereas the study of the equilibrium (steady state) reaction does not examine the protein molecule directly. Equilibrium studies have wider applicability since they usually require only a small amount of protein and do not involve the use of special equipment. Necessarily, the information obtained is indirect and often ambiguous. Although transient kinetics requires special techniques for measuring the rates of fast reactions in solutions, it provides information which is far more direct and useful for elucidating complicated mechanisms of reactions. Thus, the two approaches are complementary and both are indispensable for the study of protein reactions.
KeywordsFast Reaction Protein Reaction Elementary Step Steady State Kinetic Stopped Flow
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MIT aeronautics professor and engineer Dava Newman discusses her aim to create groundbreaking innovations in space suit design. Newman discusses space suits' need to enable exploration. Her design team's use of robots as surrogate astronauts allows for researchers to improve and revolutionize space suit design.
Improving performance and design is possible by using new systems and by conducting extensive field studies. Neman relies on detailed infographics as well as video experimentation to further space-age concepts that have the future in mind.
Dava Newman discusses the history of space suit innovations and introduces her team's 'Bio-Suit' concept. The 'Bio-Suit' encourages and enables exploration, and protects astronauts from foreign atmospheres and germs. It works as a second skin and enhances mobility allowing for full flexion. This daring and dynamic design explores technology and innovation that aims to contribute to future developments.
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Dava Newman Keynotes
The Dava Newman speeches explore her aims to create innovative space suit designs that will help... | <urn:uuid:8dada6d9-c3c1-43c7-8109-6ac4c1eaa481> | 2.71875 | 219 | Content Listing | Science & Tech. | 26.037829 | 95,586,154 |
Experimental wave-power buoy survives winter in Monterey Bay
In early January 2015, a team of MBARI engineers, led by Andy Hamilton, set out to sea to recover an experimental buoy that creates electrical energy from ocean waves. This power buoy had been deployed six miles southwest of Moss Landing Harbor for 131 days, while the engineers tested the system's ability to handle storms.
The power buoy has been in development for six years, and has been deployed and recovered six times over the past four years. Modifications after each deployment have increased the power buoy's efficiency and the amount of time it can spend out in the ocean. This most recent deployment was the longest the power buoy has been able to stay out at sea so far.
The buoy itself is eight feet across. Hanging in the water below the buoy is a long cylindrical wave-power converter that contains two pistons, a pneumatic spring, a hydraulic system, and an electrical system (see illustration). Below the power converter hangs a massive fiberglass and metal plate, about four meters (12.5 feet) wide and three meters (9 feet) long , which provides the necessary resistance to operate the buoy's piston systems.
The linear motion of the pistons inside the cylinder drives the generation of electricity from ocean waves. The current version of the power buoy can generate 300 to 400 watts of power during average wave activity, and up to 1,000 watts during storm conditions.
For this experiment, the system was anchored to the seafloor using a heavy anchor (not pictured in the illustration) to keep the buoy from drifting toward shore. The design also incorporated a stronger tether and a new plate design with built-in flaps to help alleviate stress on the power converter and tether during storms.
Unfortunately, this complicated design also makes the power-buoy system challenging to recover. However, MBARI engineers have developed an efficient method for recovering the buoy and bringing it back to the lab for maintenance. During the recent recovery, scuba divers first attached ropes to the metal plate and the power converter. Then the plate was pulled up out of the water and secured to a metal frame on the back of the boat.
Once the plate was secured, the team raised the anchor, cleaned off the seafloor mud, and hoisted the anchor on deck. Then the team hoisted the power converter up to the surface of the water and attached floats to it so it would float horizontally in the water behind the buoy. Ropes were then attached to the buoy and the whole assembly was towed behind the boat as it traveled back to the harbor.
The power buoy is still in an experimental stage, but once it is perfected, it will help address one of the most persistent challenges in oceanography—powering research instruments and undersea robots. There is currently no cost-effective way to power underwater equipment aside from batteries, which are expensive and have a limited lifetime.
Eventually, the power buoy will help scientists extend the amount of time oceanographic equipment can operate beneath the ocean surface. For example, one long-term goal of the power buoy project is to provide an underwater docking station where autonomous underwater vehicles (AUVs) can recharge their batteries while on long-term missions out at sea.
During its most recent deployment, the buoy only supplied power for instruments used to collect data for engineering purposes. These instruments included sensors that measure the amount of pressure in the pneumatic spring, a sensor that keeps track of the position of the pistons, a computer that monitors the various parts of the power buoy, and a radio system for sending data back to shore.
During the coming year the engineering team will improve the electrical AC-to-DC converter of the power buoy in order to improve the overall efficiency of the system. Hamilton's team plans to deploy the buoy again in the fall, and hopes to run electrical wires down the tether to deliver power to the submerged plate. If successful, this would bring Hamilton's engineering team even closer to creating an underwater charging station.
It may be years before the power buoy is ready to be used to power scientific equipment, but these test deployments are important steps toward extending the amount of time oceanographic instruments can operate underneath the ocean waves.
Provided by: Monterey Bay Aquarium Research Institute | <urn:uuid:985dbd1c-efd5-469e-a94e-80ef7953f6c6> | 3.4375 | 873 | News Article | Science & Tech. | 36.910581 | 95,586,159 |
Stage-3: 200-500 Years
At this point, we are in danger of entering the twilight zone, where science future can quickly become science fiction. However, we will continue trying to consider not only the effects of technology advancement, but also its impact on society. Of course, part of the problems with such long-term predictions is that we don't really understand, or share a common perception of what society will look like in 200-500 years. Therefore, the following scenario is simply to provide a framework of what the world might be like having transitioned through stage-1 and stage-2 evolutions.
The world of the 24th century is a fragmented collage of societies, cultures and beliefs, made up of some 15 billion people. However, in general, populations are now stable and in many first-world countries there is even some concern about the fall in birth rates within their own economies. It is a world that still comprises of the ‘haves’ and ‘have-nots’ in terms of food and wealth, but the ‘haves’ are also divided into those that have accepted AI technology and those that have not. In numbers, the AI technophiles are still a small minority, however given that major economies are almost totally dependent on AI technology; AI technophiles hold the balance of power in many countries. While national borders still exist, mainly for security reasons, the sense of national identity is fading, due to a range of factors:
- Continued migration of people throughout the world,
- Increase in cross-cultural relationships and marriages,
- The need for global economics and political solution,
- Fragmentation of society from within by evolution-by-design
Although, the development and introduction of new genetic crops has helped the desperate plight of cyclic starvation in many third-world countries, the growing effects of climate change has become the source of an increasing number of disasters, which has resulted in loss of vital food crops. As such, a large percentage of the world's 15 billion population still continues to live a hand-to-mouth existence. However, the technology-led economies now face problems of their own, not least, the the ever-growing demand for energy and mineral resources, which underpins the entire global economy. As a result, an international consortium of governments plus multi-national conglomerations are investing heavily in semi-automated AI robotic rigs to mine the asteroid belt and exploit new energy sources. As a consequence, AI technology in combination with developments in robotics has come to underpin, not only the hopes for economic recovery, but the perceived requirement for other habitable colonies within the solar system. However, for many, there is a new kind of despair, based on the perception that they are no longer part of the future being forged by the AI technophiles. This sense of despair does not just reside in third-world countries, but also within many individuals who live in the first-world countries, who feel that they have not, only a diminishing role in their own society, but the future itself. While this does lead to social anarchy in some inner-city areas throughout the world, the increasing ability of AI surveillance systems plus the fear of the imposition of neural implants as a result of a criminal conviction, has largely kept this problem in check. However, the side effect of this alienation from what appears to be a technophile-led society is an explosion of religious cult groups, which seeks to promote the spiritual nature of mankind; from which they believed AI is, and should remain, excluded.
As stated at the outset of this section, the future can be reached by many different paths, some planned, others created by random chance, and others by chaos. While the picture painted of life beyond the 24th century may be very disconcerting to some, it is clearly not a worst case scenario from which to consider the evolution of stage-3 AI. However, it is accepted that the scenario has been deliberately biased to reflect a growing fragmentation of society in which humanity either embraces or rejects AI technology. Although there is an implication that an organised group called the ‘AI technophiles’ has evolved, in practise, this group may simply represent the broad spectrum of acceptance. At one level, there is Homo Computerus, who accepts AI, but only as an external tool. At the next level is a small, but growing percentage that is evolving towards Homo Cyberneticus via the increased acceptance of both prosthetic and neural implants. These two evolutions are representative of stage-1 and stage-2 AI. In the 3rd stage, we are trying to consider the implications of two further evolutionary steps previously outlined by the hybrid AI paradigm:
Up to the end of stage-2, there remains a clear distinction between humanity and AI, at least, in general outward appearance. However, the preceding stage have now established the technology that has the potential to dramatically affect the physical appearance of humanity, which also raises the possibility of opening up new habitats beyond the confines of planet Earth. We have already speculated on the issue of prosthetic anatomy, but we shall present 3 of the earlier examples for continuity:
- Medical Condition
Clearly, a person with a severe physical disability or injury that is beyond the normal bounds of help, even with the best medical treatment in the world, could face a life of physical confinement. It is clear that many people would forego some aspect of their physical appearance, and even personal identity, in order to regain their independence. However, it is again stressed that a prosthetic anatomy could evolve, in the timeframe under discussion, to be both functionally superior and aesthetically beautiful. In fact, it may be entirely possible, in a case of this type, that the original appearance of the person could be replicated.
- Extreme Professions
Today, it might seem too extreme for somebody to change their physiology just to meet the demands of their profession. However, it is possible that the psychology of society beyond the 24th century is driven by different needs. It has been suggested that people may have started to question whether they have a role in society. As such, people may be more willing to 're-invent' themselves both physically and mentally in order to find some role in society beginning to be dominated by the advances in AI systems and robotics. Again, if the prosthetic anatomy was physically superior in some aspects and aesthetically acceptable, this may not be such a hard choice
- Extreme Environments
For some, life is not about their own physical form or beauty, but the beauty of exploring the universe and experiencing new wonders. However, the universe is a diverse and hostile environment and the human physiology has only evolved to meet the limited demands of a very small biosphere called Earth. To such people, the apparent sacrifice of giving up some or all of their original physical form for one that allows them to personally go out and experience the depths of space or the depths of the oceans may not be such a major issue.
At this point, it is realised that many people may be visualising
prosthetic anatomy in terms of some robotic analogy, as implied by the
picture above, which is a perception drawn from today’s technology and
not necessarily the future reality of 24th century technology. Of course,
early prosthetics will undoubtedly be crude in comparison to 4 billion
years of evolution, but it might be a mistake to assume that prosthetic
ascetics will not be high on the agenda for those interested in pursuing
this idea. Of course, these early adopters may be driven by other pressing
criteria, as suggested above, and we should not forget that there is
the potential for future prosthetics, in conjunction with genetics,
to dramatically increase the longevity of life. However, there is one
other aspect that we might take into consideration, which arises from
the acceptance of brain implants, i.e. augmented
reality. While this is the topic of another section, this technology
has the potential to transform the perception of reality. As such, future
descendents of homo sapien might have the ability to project
any avatar identity they wished into the augment reality in which they
partially exist, but it would be a reality from which homo sapien
may be excluded. Let us attempt to put this idea into some context of
the world we have created above:
- Space Exploration:
As indicated, the technology for deep space exploration is being developed to allow the solar system to be explored and mined for mineral and energy resources. While much of this operation can carried out by AI robotic systems, some aspects need Homo Machinus to be collocated within a ‘mothership’ in space. In order to survive the rigours of a life in space, while also minimising the cost and resources to maintain their on-board life-support, Homo Machinus has adapted to this new environment by replacing much its original biological anatomy. In this form, Homo Machinus has an extended life expectancy of some 300 years, based on genetically modified biological brain cells, and can survive extended periods of high ‘G’ acceleration. However, while Homo Machinus lives and works in a sparse physical reality, it also lives and enjoys much of its leisure time in a far richer artificial reality (AR). Over time, the brain-computer interface has evolved to provide direct stimulus of all primary sensory systems. As such, what Homo Machinus sees, hears, tastes, smells and touches in its augmented reality is as real, in all practical terms, as what we perceive in our current physical reality. However, in AR, there is no requirement for physical resources and therefore leisure pursuits are limited only by their imagination and the computer systems to generate the AR simulations.
Of course, in the final analysis, the ability to uncouple evolution
of intelligent life from its human physiology, as suggested, will take
time. This might allow for the different evolutionary groups to adapt
to social and political change implicit in this ‘brave new world’.
However, it is also possible that tensions on planet Earth may grow
to a dangerous level or resources simply become depleted, such that
stage-3 essentially signals the exodus of intelligent life out into
solar system and the stars beyond, albeit with precious little of its
original DNA blueprint intact. | <urn:uuid:21b49da6-3621-4934-b697-ea6a7fbadef1> | 3.0625 | 2,114 | Academic Writing | Science & Tech. | 22.954984 | 95,586,169 |
Researchers fear a fundamental change in the oceans – even if greenhouse emissions are successfully reduced
Our oceans need an immediate and substantial reduction of anthropogenic greenhouse gas emissions. If that doesn’t happen, we could see far-reaching and largely irreversible impacts on marine ecosystems, which would especially be felt in developing countries. That’s the conclusion of a new review study published today in the journal Science. In the study, the research team from the Ocean 2015 initiative assesses the latest findings on the risks that climate change poses for our oceans, and demonstrates how fundamentally marine ecosystems are likely to change if human beings continue to produce just as much greenhouse gases as before.
Since the pre-industrial era, the carbon dioxide concentration in the atmosphere has risen from 278 to 400 ppm (parts per million) – a 40 percent increase that has produced massive changes in the oceans. “To date, the oceans have essentially been the planet’s refrigerator and carbon dioxide storage locker. For instance, since the 1970s they’ve absorbed roughly 93 percent of the additional heat produced by the greenhouse effect, greatly helping to slow the warming of our planet,” explains Prof Hans-Otto Pörtner, co-author of the new Ocean 2015 study and a researcher at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research.
But the oceans have also paid a high price: as far down as 700 metres the water temperatures have risen, which has forced some species to migrate up to 400 kilometres closer to the Earth’s poles within the past decade. Given the increasing acidification in many regions, it’s becoming more and more difficult for corals and bivalves to form their calcium carbonate skeletons. In Greenland and the western Arctic, the ice is melting at an alarming rate, contributing to rising sea levels. As a result of these factors, the biological, physical and chemical processes at work in marine ecosystems are changing – which will have far-reaching consequences for marine life and humans alike.
In their new study, the research team from the Ocean 2015 initiative employs two emissions scenarios (Scenario 1: Achieving the 2-degree goal / Scenario 2: Business as usual) to compile the main findings of the IPCC’s 5th Assessment Report and the latest professional literature, and to assess those findings with regard to the risks for our oceans. “If we can successfully limit the rise in air temperature to two degrees Celsius through the year 2100, the risks, especially for warm-water corals and bivalves in low to middle latitudes, will become critical. However, the remaining risks will remain fairly moderate,” explains lead author Jean-Pierre Gattuso. But a rapid and comprehensive reduction of carbon dioxide emissions would be needed in order to achieve this ideal option, he adds.
If instead carbon dioxide emissions remain at their current level of 36 billion tonnes per year (the 2013 level), the situation will escalate dramatically. “If we just go on with business as usual, by the end of this century the changes will hit nearly every ecosystem in the oceans and cause irreparable harm for marine life,” claims Pörtner. This would in turn have massive impacts on all areas in which human beings use the oceans – whether in capture fisheries, tourism or in coastal protection.
Further, the researchers point out that with every further increase in the carbon dioxide concentration in the atmosphere, the available options for protecting, adapting and regenerating the oceans dwindle. As the authors summarise in the closing words of their study: “The ocean provides compelling arguments for rapid reductions in CO2 emissions and eventually atmospheric CO2 drawdown. Hence, any new global climate agreement that does not minimize the impacts on the ocean will be inadequate.”
The researchers’ statement above all addresses those individuals who will attend the international climate conference COP21 in Paris this December. Their study offers four key takeaway messages for the negotiators and decision-makers who will convene there:
1) The oceans greatly influence the climate system and provide important services for humans.
2) The impacts of anthropogenic climate change on key marine and coastal species can already be seen today. Many of these plant and animal species will face significant risks in the decades to come, even if we succeed in capping carbon dioxide emissions.
3) We urgently need an immediate and substantial reduction of carbon dioxide emissions in order to avoid widespread and above all irrevocable harm to ocean ecosystems and the services they provide.
4) Fourth, as atmospheric CO2 increases, the available protection, adaptation and repair options for the ocean become fewer and less effective, and with them the odds that marine life forms can successfully adapt to these rapid changes.
The Ocean 2015 initiative was launched to provide extensive information on the future of the oceans as a resource for decision-makers participating in the COP21 conference. The international research team is supported by the Prince Albert II of Monaco Foundation, the Ocean Acidification International Coordination Center of the International Atomic Energy Agency; the BNP Paribas Foundation and the Monégasque Association for Ocean Acidification.
Over the past several years, publications by researchers from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, have greatly contributed to our current state of knowledge. One of the chief questions their efforts addresses is: “How will climate change affect ecosystems in the polar regions?”
NOTES FOR EDITORS:
The review study appears in the 3 July 2015 issue of Science under the title:
J.-P. Gattuso et al: Contrasting futures for ocean and society from different anthropogenic CO2 emission scenarios, Science 3-July-2015
The full version is published online at: http://www.sciencemag.org/lookup/doi/10.1126/science.aac4722
Your academic contact partner at the AWI is Professor Hans-Otto Pörtner (E-Mail: Hans.Poertner(at)awi.de). As he is away on a business trip this week, please contact him by e-mail to request an interview.
If you have any questions, Ms Sina Löschke (tel. +49 471 4831-2008; e-mail: medien(at)awi.de) from the Department of Communications and Media Relations will be pleased to assist you.
The Alfred Wegener Institute pursues research in the Arctic, Antarctic and the oceans of the middle and high latitudes. It coordinates polar research in Germany, while also providing essential infrastructure for the international scientific community, including the research icebreaker Polarstern and stations in the Arctic and Antarctic. The Alfred Wegener Institute is one of the 18 Research Centres of the Helmholtz Association, the largest scientific organisation in Germany.
Ralf Röchert | idw - Informationsdienst Wissenschaft
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Materials Sciences
18.07.2018 | Life Sciences
18.07.2018 | Health and Medicine | <urn:uuid:eaeebf74-c912-4875-ac80-1f9eb4938c8a> | 3.515625 | 2,076 | Content Listing | Science & Tech. | 35.780689 | 95,586,178 |
Marine reserves are being established worldwide in response to a growing recognition of the conservation crisis that is building in the oceans. However, designation of reserves has been largely opportunistic, or protective measures have been implemented (often overlapping and sometimes in conflict) by different entities seeking to achieve different ends. This has created confusion among both users and enforcers, and the proliferation of different measures provides a false sense of protection where little is offered. This paper sets out a procedure grounded in current understanding of ecological processes, that allows the evaluation and selection of reserve sites in order to develop functional, interconnected networks of fully protected reserves that will fulfill multiple objectives. By fully protected we mean permanently closed to fishing and other resource extraction. We provide a framework that unifies the central aims of conservation and fishery management, while also meeting other human needs such as the provision of ecosystem services (e.g., maintenance of coastal water quality, shoreline protection, and recreational opportunities). In our scheme, candidate sites for reserves are evaluated against 12 criteria focused toward sustaining the biological integrity and productivity of marine systems at both local and regional scales. While a limited number of sites will be indispensable in a network, many will be of similar value as reserves, allowing the design of numerous alternative, biologically adequate networks. Devising multiple network designs will help ensure that ecological functionality is preserved throughout the socioeconomic evaluation process. Too often, socioeconomic criteria have dominated the process of reserve selection, potentially undermining their efficacy. We argue that application of biological criteria must precede and inform socioeconomic evaluation, since maintenance of ecosystem functioning is essential for meeting all of the goals for reserves. It is critical that stakeholders are fully involved throughout this process. Application of the proposed criteria will lead to networks whose multifunctionality will help unite the objectives of different management entities, so accelerating progress toward improved stewardship of the oceans.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:45929a06-8e89-448e-8347-6f926954003a> | 3.046875 | 389 | Academic Writing | Science & Tech. | -1.774796 | 95,586,179 |
Multi-mineral geochronology: insights into crustal behaviour during exhumation of an orogenic root
MetadataShow full item record
Under rare conditions, reworked cratons and their margins preserve the orogenic roots of ancient mountain-building events. However, based on the preservation of high-temperature (~ 800 °C), middle and lower crustal metamorphic assemblages, present day exposure of these terrains is not simply a result of protracted denudation, but also must reflect a multifaceted exhumational history. In situ analysis within thin section preserves the textural setting of target minerals that can be used as thermochronometers such as U-Pb of zircon, monazite, titanite and apatite, and Sm-Nd of apatite. In situ analyses of these chronometers has the potential to provide critical timing constraints on exhumation processes related to decompression, melting and cooling across large metamorphic terrains. The Repulse Bay block of the Rae craton preserves a large composite amphibolite–granulite area (50,000 km2) of Archean orthogneiss, migmatite, and slivers of Proterozoic metasediments that underwent high-grade metamorphism, partial melting, ductile flow and finally exhumation during the Paleoproterozoic Trans-Hudson Orogeny. The granulite domain preserves dry granitoid assemblages, whereas the amphibolite domain is dominated by hydrated migmatites and orthogneiss. Metasediments occur in both domains and preserve mineral assemblages that are consistent with having undergone tectonometamorphic conditions of ~ 9 kbar/800 °C during burial. U-Pb thermochronometers document identical cooling histories of the granulite and amphibolite domains through the U-Pb closure temperatures of titanite (~ 650 °C) and apatite (~ 450 °C). This suggests that melt-loss from the underlying granulite domain and melt-gain to the amphibolite domain prior to cooling through 650 °C are a controlling factor of the metamorphic assemblages across the composite granulite–amphibolite terrains such as the Repulse Bay block, rather than significant differences in burial history, cooling history, and/or reorganization of the crust.
Showing items related by title, author, creator and subject.
Rapid cooling and exhumation in the western part of the Mesoproterozoic Albany-Fraser Orogen, Western AustraliaScibiorski, E.; Tohver, E.; Jourdan, Fred (2015)© 2015 Elsevier B.V. The Albany-Fraser Orogen of southwestern Australia is an understudied orogenic belt, which is interpreted to record the Mesoproterozoic suturing of the Yilgarn Craton of Western Australia to the Mawson ...
Rapid cooling and exhumation in the western part of the Mesoproterozoic Albany-Fraser Orogen, Western AustraliaScibiorski, E.; Tohver, E.; Jourdan, Fred (2014)The Albany-Fraser Orogen of southwestern Australia is an understudied orogenic belt, which is interpreted to record the Mesoproterozoic suturing of the Yilgarn Craton of Western Australia to the Mawson Craton of East ...
Osumilite–melt interactions in ultrahigh temperature granulites: Phase equilibria modelling and implications for the P–T–t evolution of the Eastern Ghats Province, IndiaKorhonen, Fawna; Brown, M.; Clark, Christopher; Bhattacharya, S. (2013)The exposed residual crust in the Eastern Ghats Province records ultrahigh temperature (UHT) metamorphic conditions involving extensive crustal anatexis and melt loss. However, there is disagreement about the tectonic ... | <urn:uuid:aa3a9a78-5258-4f23-b48a-104c09b9d7d3> | 2.734375 | 838 | Academic Writing | Science & Tech. | 13.402685 | 95,586,198 |
Evidence for Circannual Rhythms
Although a considerable amount of evidence suggesting endogenous annual clocks in plants and animals was accumulated during the first half of this century, their existence was not demonstrated before the early 1960’s. The most compelling evidence then was provided by the work of Pengelley and Fisher (1957, 1963) with golden-mantled ground spuirrels (Spermophilus lateralis). Figure 2.1 shows the seasonal changes in body weight and food consumption, as well as the occurrence of hibernation, in two ground squirrels maintained for about 2 years under a constant LD 12:12 and constant temperature conditions. Both animals continued to hibernate about once a year, and each period of hibernation was preceded by a dramatic increase in body weight and food consumption. The general pattern of these seasonal functions was rather similar to that in free-living squirrels with an obvious difference that can be seen particularly clearly in the squirrel maintained in 0 °C. In the first year of the experiment this animal entered hibernation in late October, but in the second the onset of hibernation had shifted forward to mid-August and in the third to early April. In other words, the period measured between onsets of hibernation was shorter than 12 months.
KeywordsSika Deer Willow Warbler Garden Warbler Circannual Rhythm Testicular Size
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External Flow: Mass Transfer. Chapter 7 Sections 7.2 - 7.5, 7.7, 7.8. Mass Transfer. Mass Transfer. Correlations for convection mass transfer coefficients associated with evaporation or sublimation from liquid or solid surfaces in external flow may be inferred from
Sections 7.2 - 7.5, 7.7, 7.8
Hence, with , the properties of the mixture may be approximated by those of species B.
(assuming saturated conditions).Mass Transfer
species B (the free stream fluid).
If the correlation involves a property ratio, approximate
the ratio as unity.
How would you characterize the relative effectiveness of diffusion in gases, liquids
Problem 7.119 Use of radiant energy to dry slurry in a paper production process.
Problem 7.128 Use of wet- and dry-bulb thermometers to determine
temperature and relative humidity of air flow in a duct. | <urn:uuid:5d7ba573-dd87-4663-a41e-6f408d9b4cfc> | 2.765625 | 197 | Content Listing | Science & Tech. | 60.67063 | 95,586,229 |
Control at the atomic scale is being realized by researchers across the world through synthesis of quantum dot materials. Take a look at an overview of what makes these tiny particles so special.
Computational chemistry is much more than computers and chemistry! Let’s have a brief tour in the world of computational chemistry!
Enzymes are nature’s catalysts. But there are not enough enzymes for all the reactions in the world! How do chemists design enzymes? Let’s take a look!
Fake medical tests are a huge problem in many poorer countries. Let’s learn about a way to print erasable codes on these devices so they can’t be counterfeited!
Machine learning? Deep neural networks? Find out how advances in artificial intelligence could help scientists discover new materials.
Successful resistance to a viral infection requires the host to deploy incredibly intricate biological tactics that somehow selectively inhibit key processes in the viral lifecycle. In this paper, researchers delve deeper into the molecular mechanisms of one of such resistance mechanisms!
Nanowires are part of the future of smaller, smarter electronics. Here’s a interesting new method of making metal nanowires.
Catalysis is a common chemistry concept, but there are many intricacies involved. Check out some of these lesser-known facts!
Researchers have expanded the forensic analytical chemistry toolkit to include a model for Raman spectroscopy identification of blood donor age.
Although getting the common cold is not a nice experience, it is only a relatively minor misfortune for most people. But the consqeuences of a cold can be severe. This paper describes a significant step towards a cure!
The sea can sequestrate carbon dioxide from the atmosphere and some rocks can help to enhance this phenomenon! But which ones? and how?
Rub a ruler with a wool and hold it towards paper bits, then you’d find the ruler attracts papers. This may sound a common sense to you – the two surfaces have opposite charges.
But now, researchers find that not all materials behave the same and the reason is still a mystery.
Let’s take a look at the charges that challenges scientists!
Making surfaces that oil can’t stick to is important for cleaning up oil spills and other pollution. Let’s find out about a new way to coat surfaces that makes them repel oil!
What will medicine look like 10 years from now? Well, your doctor might be shining a light on you to help target drug delivery in your body. Read more about drug delivery using molecules called photocages inside!
Aging infrastructure containing lead contaminates too many water sources in the US, and worldwide. For the first time, researchers have developed a material, based on a metal-organic framework, that almost instantaneously brings lead- and mercury-contaminated water to safe drinking levels. Could this be the next generation of water filters?
Microorganisms are particularly remarkable at churning out structurally challenging small molecules with interesting biological functions. In this work, an unprecedented chemical transformation in one such natural products is discovered and characterized.
Discover how rice husk be converted into structures like carbon nanotubes and lithium battery anodes!
Given our current rate of plastic consumption and generation, can our planet win over plastic? Can we save our planet and still use plastic? In this article, discover how chemists at Colorado State University have synthesized a new kind of plastic that can be recycled infinitely without losing its functionality!
Are you passionate about Chemistry and sharing its wonderfulness?
Do you like writing?
If yes, here’s a chance for you to be a writer for Chembites!
A new form of DNA was found in vivo. It can be a way to regulate the DNA replication and thus prevent the replication of tumor cells.
Currently, nanoparticles are not talking to each other while working. In this article, we explore how researchers break the ice between nanoparticles and design a new class of materials by establishing a connection. | <urn:uuid:06c08605-afd2-4660-9d1c-1db54c7697ec> | 3.0625 | 825 | Content Listing | Science & Tech. | 39.496979 | 95,586,232 |
In plant physiological and ecological studies, leaf measurements are often critical, but traditional methods have been time consuming and sometimes destructive to plant samples.
Researchers at the University of California, Davis, have developed Easy Leaf Area—a free software written in an open-source programming language—to allow users to accurately measure leaf area from digital images in seconds.
"It has always been a challenge to measure leaf surface area without damaging the plants or spending long hours in the lab, so I decided to attempt to write software to automatically measure leaf and scale area from smartphone images," explains Hsien Ming Easlon, a researcher at UC Davis and one of the developers of Easy Leaf Area. "Leaf area measurements are essential for estimating crop yields, water usage, nutrient absorption, plant competition, and many other aspects of growth."
The digital images he uses are taken with the Apple IPhone 4, but any current smartphone camera or digital camera will do. Once the images are uploaded to a computer, Easy Leaf Area can process hundreds of images and save the results to a spreadsheet-ready CSV file. The Windows executable software is free to download and can be modified to suit specific experimental requirements. A full report including links to additional resources is available in a recent issue of Applications in Plant Sciences
Easlon recalls, "Our lab started using digital cameras when I was a graduate student. We figured out how to use Photoshop to measure areas in digital images, but this method still required one to five minutes of human input per image."
Five minutes per image may not seem like a long time, but multiply that by hundreds of plants—a normal sample size—and those minutes add up fast. By automating data analysis, researchers can save countless hours of manual labor, improve the accuracy and consistency of their results, and reduce potential damages to their plant samples.
Easlon and his team developed Easy Leaf Area using Arabidopsis
plants, and also tested Easy Leaf Area on photographs of field-grown tomatoes and wheat, and photographs and scans of detached leaves of a common tree poppy, California redwood, chaparral currant, Jeffrey pine, and Valley oak. Manual adjustments to the automatic algorithm can be saved for different plants and field conditions, making this a practical tool for researchers in many plant science fields.
Easlon's next step is to develop a mobile version so that leaf area measurements can be made on the fly without a PC. He also plans to add handwriting recognition or barcode reading to the software. This will automatically interpret labeled plant stakes and assign the proper file names to each image.
"Most researchers don't have the time or knowledge to develop software for themselves, so scientific use of smartphones is primarily limited to built-in features. The processing power, connectivity, built-in sensors, storage capacity, and low price give smartphones great potential to replace many single-purpose devices for scientific data collection," explains Easlon.
Calculating plant surface area could soon be as easy as using Instagram. | <urn:uuid:adb7cbf7-dd75-418c-a163-16fc3fb879bc> | 3.21875 | 609 | News Article | Science & Tech. | 21.098095 | 95,586,235 |
Isotopic Properties of Selected Elements
Part of the Minerals and Rocks book series (MINERALS, volume 9)
Until 1931 it was assumed that hydrogen consisted of only one isotope. Urey et al. (1932a, b) detected the presence of a second, heavy, stable isotope, which was called deuterium. Way et al. (1950) gave the following average abundances of the stable hydrogen isotope:
KeywordsStable Isotope Oxygen Isotope Isotope Fractionation Hydrogen Isotope Sulfur Isotope
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
Unable to display preview. Download preview PDF.
© Springer-Verlag Berlin Heidelberg 1980 | <urn:uuid:dd2da5b4-e06a-4ef7-bf1c-ee2ce2fd001c> | 3.484375 | 173 | Truncated | Science & Tech. | 23.9325 | 95,586,248 |
Researchers compare reproduction rates in North Atlantic whales with genetic variation
A recent study focusing on the humpback whales of the Gulf of Maine revealed that differences in reproductive success of whale mothers may play a significant role in changing genetic variation in the population, according to scientists from the Wildlife Conservation Society (WCS), the American Museum of Natural History and their collaborators. Specifically, certain maternal lines of whales have produced more calves than other lines in the past decade, a finding that uncovers the often-complex role of genetics and environment in the makeup of this population of long-lived mammals.
In the study, published in the most recent issue of The Journal of Heredity, researchers compared more than two decades of field observations on humpback whales from the Whale Center of New England with genetic samples collected with biopsy darts, which remove a small piece of skin from the backs of these marine mammals. If current trends continue, the humpback whale population of the Gulf of Maine could show shifts in genetic variation over the next 75 years, with some maternal lines becoming more common than others.
John Delaney | EurekAlert!
Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung
Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:0ee532bc-3ae3-4666-bb4e-7b5029817570> | 3.46875 | 866 | Content Listing | Science & Tech. | 37.404772 | 95,586,252 |
A nuclear reaction is a process that occurs when a nuclear particle (nucleon or nucleus) gets into close contact with another. Most of the known nuclear reactions are produced by exposing different materials to a beam of accelerated nuclear particles. Usually a strong energy and momentum exchange takes place and the final products of the reaction are one, two, or more nuclear particles leaving the point of close contact in various directions. The products are mostly of a species different from the particles in the original pair. The present chapter contains a wave-mechanical description of nuclear reactions and a general analysis of the phenomena that are expected to occur.
KeywordsAngular Momentum Nuclear Reaction Elastic Scattering Orbital Angular Momentum Target Nucleus
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“We are looking for the conditions of life, rather than life itself,” said Douglas Whittet, director of the New York Center for Astrobiology and a Rensselaer professor of physics, applied physics, and astronomy. The center opened in 2008 with support from NASA.
One interesting finding from its research thus far is that stars aid in the process of forming the more complex matter found on planets and in life.
“You need energy to drive the chemistry. A star itself can cook simple molecules into something more interesting,” Whittet said.
The new four-year $630,000 grant will allow the center to expand operations.
“It will allow us to support some more collaborations, which in turn lets us acquire and analyze more data,” Whittet said.
Researchers at the center study the chemical, physical, and geological conditions on Earth that gave birth to life. That information, in turn, is used to search for similar conditions elsewhere – on Mars and other bodies in our solar system, and on planets orbiting other stars.
“A lot of organic molecules present on Earth may have been delivered shortly after it was formed. The evidence for this comes from meteorites, which contain amino acids,” Whittet said. “We aim to find out what was happening in the solar system 4.5 billion years ago when it was formed. When and how was this matter synthesized, and how common is it?”
The researchers look for clues within young solar systems, where stars are surrounded by molecular clouds or pre-planetary disks that have not yet coalesced into planets.
The key to their research is spectroscopy – or light signature – of the clouds and disks. The early universe was composed of hydrogen and helium, from which other elements were formed, and later combined into molecules in interstellar clouds. By examining the light signature of the material, researchers can determine which chemicals are present in a particular cloud or pre-planetary disk.
“You use the star as a source of radiation. The material between you and the star is absorbing some of it. We look at the absence of light caused by the material,” Whittet said.
Whittet said researchers are currently analyzing data gathered from the Spitzer Space Telescope – an infrared telescope orbiting the sun that gathered data from 2003 to 2009.
“There’s a huge archive of data that’s being analyzed, and the grant will afford us access to more of that material,” Whittet said.
Already that material has yielded the insight that stars play a role in the creation of more complex matter. Whittet explained that molecular clouds around stars mature into pre-planetary disks and then planets. Complex matter is found in increasing abundance as the stages progress.
“Organic molecules such as hydrocarbons and alcohols are more common in pre-planetary disks compared with molecular clouds,” Whittet said. “These molecules form with the help of energy from the star.”
A less promising finding – at least from the standpoint of finding life elsewhere in the universe – is the relative scarcity of complex hydrocarbons.
“The most common material we’ve found is carbon dioxide, which is not very useful in making life,” Whittet said. “It would be a lot more interesting if the carbon were going into hydrocarbons, which are a stepping point to much more complicated molecules.”
Mary Martialay | Newswise Science News
What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | 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
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering | <urn:uuid:e2b1db58-5657-46a5-b9e4-5eb5c992f04e> | 3.75 | 1,373 | Content Listing | Science & Tech. | 42.653547 | 95,586,277 |
Even if we eliminate all greenhouse gas emissions today, climate change is here to stay. That means we must prepare for more and more events like Hurricane Sandy – in part by replacing our tar and concrete infrastructure with green systems that mimic and incorporate nature. Fortunately, this transformation is already underway.
2 November 2012 | When New York Mayor Michael Bloomberg endorsed Barrack Obama’s reelection bid on Thursday, he did more than just embrace the scientific consensus on climate change. He also demonstrated an awareness of the fact that our entire economy is embedded in – and dependent on – nature.
Locally, the awareness has been manifest in a debate over whether or not to build sea gates off the New York shore, but it really goes much deeper than that. In the weeks and months ahead, we can expect to hear more about the need to revive the planet’s once reliable “green infrastructure” – and, in New York’s case, that means replenishing the salt marshes that once acted as natural surge protectors, restoring the wetlands that once provided water filtration and flood control, and righting the rivers and streams that once dealt so effectively with stormwater runoff.
New York City has already taken steps in this direction. Over the past two years, it launched both an ambitious “green infrastructure” plan aimed at rivers and streams, and a wetlands strategy aimed at salt marshes and wetlands.
Such natural elements are often better at protecting the coast because they don’t muscle storm surges but rather absorb them. They also tend to be cheaper to build and maintain than are massive engineering works, and they’re almost always prettier to look at. Done right, they can even pay for themselves over time.
How to Pay For It
New York is hardly alone in this endeavor. Philadelphia, for example, has developed innovative financing mechanisms that use stormwater fees to finance the installation of absorbent “green” sidewalks, roofs, and parking lots, while also restoring nature.
Such mechanisms can help us build a green infrastructure that is more resilient in the face of disasters like Hurricane Sandy – the costs of which are spiraling upwards in the US and globally, as two recent reports from insurance giants Munich Re and Swiss Re show. Each published their reports in the past year documenting the magnitude of the issue and calling for action to reduce exposure of communities and business to the risks from natural disasters.
Where is the Evidence
More and more scientific studies show that ‘natural infrastructure’ along our rivers and coasts can play a significant role in reducing the damage from storm surges. A 2007 study of New Jersey’s wetlands, for example, estimated that freshwater wetlands saved the state $9.4 billion per year in filtrating and flood control costs, while its saltwater wetlands delivered $1.2 billion per year in protection. This, of course, was before Hurricane Sandy, and well after the state had lost most of its protective wetlands. Hackensack, NJ – one of the hardest hit states in Hurricane Sandy – lost more than 75% of its wetlands between 1889 and 1995, according to the US Geological Survey.
The state of Delaware, which has lost more than 50% of its historic wetland area, has found a similar pattern, and in 2008, a team headed by ecological economist Robert Costanza looked at economic damages associated with 34 major hurricanes in the US since 1980. They found that areas with coastal wetlands experienced lower damages compared to areas without coastal wetlands – to the tune of up to $100,000 in damages per hectare of lost wetland.
Restoring these natural barriers and filters isn’t cheap, but it’s often less expensive than implementing massive engineering projects like sea gates. What’s more, as Philadelphia has shown, the knock-on benefits of developing green-infrastructure projects makes them incredibly easy to finance – with a bit of creativity.
This adds to their cost-effectiveness, because reversing the loss of this natural infrastructure also has many other co-benefits – including healthier fisheries along our coasts, increased habitat for shorebirds and other animals, recreation and tourism opportunities, improved water quality, more abundant shellfish, and scenic beauty.
This is something New York has demonstrated especially well over the last 15 years, thanks to the success of its own innovative water delivery system. Rather than spend billions on a new filtration plant, the city pays farmers in the Catskills to maintain the watershed. Two years ago, Denver started a similar program.
As the science comes into focus, financial incentives are following suit. Insurance companies, for example, say they may offer lower rates for municipalities that take into account the risk reduction value from natural infrastructure, and several efforts are underfoot to recognize natural infrastructure as an asset on financial balance sheets – which makes it easier for utilities, businesses and municipalities to finance protection and restoration of natural infrastructure.
These are just some of the potential solutions kicking around out there, and more will follow if politicians take the lead. That leadership starts with questions like the one New York Governor Andrew Cuomo tweeted on October 30, when he asked “How do we redesign the system to make sure this doesn’t happen again?” | <urn:uuid:585bf1c5-28eb-4939-9897-f46428a037af> | 2.6875 | 1,068 | Knowledge Article | Science & Tech. | 31.200942 | 95,586,312 |
New Planetary Cold record discovered? Not so Fast!
As Jeff Masters blogged on December 10th
satellite data indicates that a temperature of -93.2°C (-135.8°F) had been measured at a site near Dome Argus in Antarctica on August 10, 2010, colder than any land-based measurement from the frozen continent (that being Vostok’s -89.2°C/-128.6°F on July 21, 1983). Unfortunately, many media outlets headlined this as a “new coldest temperature recorded on earth”. This is not the case, however, so far as being an ‘official’ earth record.
Satellite earth skin temperature measurements will never be accepted as ‘official’ weather observations no matter how accurate their data might be. As Vyacheslav Martyanov, the head of the Russian Antarctic Expedition's logistics center, put it in an interview for RIA Novosti (A Russian News Organization): “It is incorrect to declare a temperature record based on satellite data. AVHRR and MODIS are measuring the so-called ‘luminance temperature’, which does not fully correlate with true meteorological conditions and must be confirmed by observations on the ground.
Air temperature is measured according to standards, at the height of 2 meters above the ground, like they do at meteorological observing stations, therefore recognizing a temperature measured by remote sensing is unrealistic”
This holds true as well for the often cited 70.7°C (159.3°F) “hottest temperature on earth” measured by MODIS in July 2005 at a remote location in the Lut Desert of Iran.
That being said, the MODIS Antarctica figure is probably closer to the truth than the Lut Desert figure since heat radiating off the desert ground in Iran would have naturally related to much hotter figures than what would have been observed had a standard weather shelter been in place at the same location. This would not have been an issue in Antarctica during its winter months. Furthermore, the location is at or near the highest point on Antarctica’s continental dome at some 4000 m (about 13,000’). The nearest weather station to the point where the cold temperature was measured is Dome Argus (also known as Dome A). See map below:Map of Antarctica illustrating where the satellite measurements were taken in relation to Dome Argus and Vostok.
Ted Scambos, National Snow and Ice Data Center.
Unfortunately, I cannot find the temperature data for Dome Argus for either August 10, 2010 or July 31, 2013 to compare to the satellite data. However, Vostok 600 meters (almost 2000’) lower than Dome Argus and, admittedly far away) did measure -110°F (-78.9°C) on July 30, 2013 and -103°F (-75.0°C) on July 31, 2013. The coldest RAWS site for the day of July 31 was -81.7°C (-115.1°F) at Davis Lab 46 located at 75.51 S, 71.29 E and at just 2354 m (7,700') elevation. One can imagine, therefore, that it most likely was considerably colder at Dome Argus or at the satellite data point on those dates (although not unquestionably given the distance from Vostok and Davis Lab 46). Also, this past summer (2013) was one of the warmest on record for much of Antarctica, especially the dome region. Vostok failed to drop below -80°C for its first time ever (POR (back to 1957) and the same goes for Dome Fuji. This begs the question of just why this little satellite data point seems to have bucked this trend (of an unusually warm winter on the dome) and yet coming up with a temperature so far away from the land site observations!A photograph of the weather station at Dome Argus (Dome A) taken shortly after its installation in 2005.
Photo credited as CHINARE and from the Australian Bureau of Meteorology web site.
Since Dome Argus was established in 2005 the coldest temperature measured there has been ‘just’ -82.5°C (-116.5°F) in July 2005 (although that was for the POR of only 2005-2010). One may assume that one of these days it is almost certain that Dome Argus or one of the other high altitude RAWS stations are going to actually measure a temperature colder than Vostok’s.
Christopher C. Burt | <urn:uuid:d510c413-6c89-472c-8718-202ea85e4a31> | 3.15625 | 947 | Comment Section | Science & Tech. | 54.981951 | 95,586,320 |
http://www.theguardian.com/global-development-professionals-network/20… Click count:1767
Did Nasa scientist, James Hansen's statement to the US Senate in 1988 kick off the climate movement? Photograph: Christopher Furlong/Getty Images
Was there a definitive moment when the scientific community reached a consensus about climate change?
Climate scientists are canaries in the coalmine - highly attuned to sense danger before we blunder into it. For decades, various researchers have issued calamitous warnings about climate change. But was there a moment when science collectively, definitively, dropped off the perch?
During the 1990s, scientists were still debating the most basic assertions of climate change science. Was the world indeed warming? Consensus was growing, but slowly and many scientists remained undecided.
Two bold scientific statements bookended the decade – James Hansen's statement to the US senate in 1988 and the 1999 hockey stick graph. Maligned and celebrated, the two were influential in bringing climate change into the public consciousness. Yet both were accused of using unproven methods to reach their conclusions, damaging the credibility of climate science and paving an easy road for denialism.
Hansen, head of Nasa's Goddard Institute for Space Studies, told the energy and natural resources committee of the United States Senate in 1988 that his research on human-induced global warming was unequivocal. "The greenhouse effect has been detected, and it is changing our climate now."
The next day, the New York Times ran the headline "Global Warming Has Begun". It was a galvanising moment for public opinion and Hansen became a poster boy for the environment movement, but not all were convinced.
"Hansen was a scientist that bumped right up against the edge of activism and a lot of scientists have been very uncomfortable going over into that. And rightly so ... if you're seen too much as an activist then people won't trust your science," said Marshall Shepherd, 2013 president of American Meteorological Society.
The US National Climate Assessment (NCA), released last week, echoed Hansen's words 26 years later: "Climate change is already affecting the American people".
But even the NCA, built as it was on the work of 800 scientists, has been criticised for a lack of nuance.To maintain credibility, climate science must walk the narrow ledge between conservatism and activism.
Some scientists feel the hockey stick graph, published in 1999, dangled both feet over this edge. Michael Mann, Raymond Bradley and Malcolm Hughes used data gathered from tree rings, lake sediments, ice cores and corals to recreate the global temperature over the past 1,000 years. The image they produced was a startling visual communiqué of the world's post-industrial warming trend. It was featured prominently in the Intergovernmental Panel on Climate Change's (IPCC) 2001 report.
But Mann et al's willingness to use unproven methodology irked some scientists, including Hulme: "I don't think it was seminal for scientists. To me that was never a decisive interventional piece of evidence. The data was absolutely scanty."
Shepherd disagrees. "I think it would be characterised as a watershed moment in climate science," he says, although he recognises it as "one of the singular most polarising graphs or scientific pieces of data that exist".
The problem for Mann and Hansen is the world wants to see all the canaries keeling over together, a clear public moment of unequivocal proof. Shepherd says the public wrongly see science like a court case, in which reasonable doubt can outweigh a larger body of evidence. But science has a natural indifference to the desire for certainty. Each time a scientist gets too far ahead of the curve it makes the scientific community deeply uncomfortable. Disagreements of this kind can be latched onto as evidence that the scientific process is flawed, fuelling the denial movement.
Consensus on climate change built incrementally through the 1990s until, by the time the 2001 IPCC report came out (with the hockey stick graph in it), there were very few scientists who felt uncomfortable attributing some climate change to human activity.
But Hulme says there was no collective eureka moment and there will always be doubt and questions. "Science doesn't really do that. It is always an unending process of confirmation, correction, refutation … It is the collective social practice of science that in the end gives science its particular credibility and status. But it's a rather harder thing to get to the bottom of because you can't just focus on one charismatic individual."
Notably absent from the consensus building of the 1990s were the voices of climate scientists from developing countries, says Chandra Bhushan, deputy director of the Centre for Science and Environment in Delhi. For the most part, this was because the research was simply not happening. But increased interest from political leaders during this time led some countries (mainly in the Indian subcontinent, China and southeast Asia) to implement climate science programmes. Even so, the imbalance perpetuates today.
Bhushan says climate scientists from the south "still play a very little role in developing consensus on climate change negotiations." The latest IPCC report drew more than 90% of its research material from developed countries.
Scientists participate in the compiling of IPCC reports with funding from their governments, meaning wealthy countries can afford to participate more in the process. This has the effect, Bushan argues, of politicising the reports, which he says have focussed unduly on the impacts of climate change on the developed world. | <urn:uuid:deff4a53-80c9-4908-a020-22da4d1f6de7> | 2.671875 | 1,134 | News Article | Science & Tech. | 39.395577 | 95,586,322 |
This chapter examines the shape power of subatomic structures.
The atom is the ultimate, original, shape power structure. Its perpetual vibration and motion reveals that it operates at the interface of the physical universe with the aetheric realm. All known forces and elements are embedded in the structure of the atom, and probably many more that we don't yet know about. Solve how the atom does its perpetual motion miracle and you have solved how the physical universe is constructed. Gravity control and free energy will be some of the resulting developments when the atom is understood.
In chapter one, the simple atom, as envisioned by John E. W. Keely, was depicted as a torroidal vortex of aetheric force, with a substructure of torroids embeded within the larger torroid in a triple particle effect. The main torroid is made up of three smaller torroids rotating to form the larger main pattern, with each pattern repeating at each sub-level, possibly ad infinitum.
Modern physics envisions the atom as a collection of nuclear particles which are held together by the strong force, the weak force, gravity, electricity, and magnetism to form the various atomic elements. Their theory is that the center of the atom has a nucleus, a core of these subatomic particles, which is surrounded by a cloud of electrons orbiting the nucleus at tremendous speed.
Neither Keely's model without electrons nor the modernist view with their particle soup is a satisfying concept. Electrons exist, at least particles that look like them, smell like them and quack like them, so Keely's model is incomplete or we simply don't have enough information to define it. Further, an electron or a cloud of them continuously rotating about the nucleus should quickly deplete their energy through electromagnetic radiation so we have more anomalies to deal with.
On the other hand, the particle menagerie of the "standard model" seems to exist but only for the most fleeting of moments. The stable particles (i.e., those which exist independent of the atom are the electron, positron, proton, and anti-proton. Some might ask, "isn't the neutron a stable particle?"; observation shows it quickly devolves into an electron and a proton.
A new model of the atom is emerging from the alternate science researchers that seems to satisfy experimental observations. This chapter describes this new atomic model. Atomic structure is described by this new model, and we are able to derive the nuclear and physical constants, plus the model forms the basis for a grand unified-field theory. None of the alternate science researchers, that I analyzed, including myself, have the full picture; but it looks like we are moving in the correct direction. I have endeavored to put all the parts together to have a more complete theory and form a cohesive picture of the atomic level and the basic nuclear forces. The researchers that formed the core ideas are listed in the bibliography.
The essence of this new model is that the electron, proton. positron, and anti-proton are all torroidal (i.e., donut shaped) shaped particles that rotate at the velocity of light. The neutron is the result of an electron and proton being compressed in the nucleus.
When I was first getting into a study of alternate physics and science back in the 1950's, my first brush with an alternative to the standard model of modern physics was with John E. W. Keely's torroidal structure of the nucleus. Having been educated ("brainwashed") by my classes in nuclear physics, atomic chemistry, and electronics, Keely's "atom" was a source of extreme puzzlement. On one hand, the evidence that Keely had truly discovered a certain modicum of control of gravity and magnetism was astounding (and way beyond modern physics), but I was never able to fully reconcile what he did with what he said was the physical basis for the atom. His atom was not adequately explained in the scant literature available and I couldn't make out if the particles Keely described were electrons, protons, neutrons, or what. My conclusion (circa 1959) was that Keely's concept of a torroidal particle structure was probably close but his subatomic structure was as goofy as the standard model. I decided that the short-lived subatomic particles were nothing more that the residue of a torroidal nucleus, made of the aether, getting blasted apart and the harder it got blasted the more accelerator that physicists used to blast the nucleus found new particles to add to the particle menagerie, possibly particles frorn Keely's substructure of smaller and smaller torroids.
I am going to give a partial derivation of the mathematical formulas which describe the new alternate atomic model; however, if the reader wants to see the nitty gritty details, look into the articles listed in the bibliography at the end of this chapter. By and large, I have steered away from mathematical descriptions in preceding chapters and attempted to form a word and graphic depictiont of the various elements of shape power to make this fascinating subject appealing, understandable, and usable to the serious researcher who may not have a mathematicaf background. In this chapter, I am going to show there is a very firm mathematical basis for this new physics. If math isn't your forte, then read the words and study the pictures, they tell the same story and you'll get 80% of the essential concepts.
My first real brush with the electron as a torroidal structure, that had some mathematics associated with it, was the seminal work done by Dr. Paramahansa Tewari1,2,3,4,5. Subsequent modeling by Paul Stowe6,7 filled in more of the puzzle of gravitation, Dr. Hal Puthoff8 and his associates clarified the concept of inertia, and recent work by Lucas and Bergman9,10,11,12 solves another set of my questions about the nucleus and atomic structure and how the structure goes together geometrically. What follows is a unified concept of these. I don't pretend that this is the end of the discussion of nuclear structure, but at least its a place to start developing a new, rational structure of matter and the universe, and to form a theoretical basis for a new picture of shape power research efforts.
8.2 The Torroidal Electron
Space is envisioned as a superfluidic medium, nonviscous, relatively frictionless, massless and continuous. It can be modeled as a particulate superfluid with average interaction spacing of L. Essentially, this is a new definition of the aether.1
The electron is postulated as a torroidal (i.e., donut shaped) ring. The ring with a radius of R and a cross section of r, rotates with a velocity of c, the speed of light. The ring (or more properly the toroid) also rotates within itself around the cross-seclion with radius r. The electron's electric charge and associated electrostatic field properties can be shown to be a result of the two rotations of the ring on it axis and cross-section.
In the classical theory of kinetics, the transverse wave speed in a fluid is:
Where P is the pressure and is the fluid density.
From electrostatics the velocity of light, c, is related to the permeability 0, and the permittivity 0 of free space. The relationship is:
Equating (1) and (2):
Since light is a transverse phenomena, we find that 0 = 1/P, the coefficient of compressibility, and 0 = which is mass/density.
To find Plank's constant we define a field vector entity as follows:
S = Space
V = Velocity
Z = momentum
L = average movement or mean free path
t = rate of momentum
h = action parameter
mz = mass or apparent mass and Z = mzV (from kinetics)
There are n of these entity vectors in a given space. The action parameter is defined as follows:
Substituting for Z = mzV,
h = 2mzVL
The total energy of the system is the integral:
The rate t is V for wave velocity and c (i.e., the speed of light) for electromagnetic radiation.
E = hV for wave motion (6) E = mzC2 for relativistic energy (7)
Since equation 6 is the same as the energy in an electromagnetic wave, then h is Plank's constant.
The quantity of charge relates to the charge of an electron. The electron is defined as a torroid with area a = 42Rr and volume S= 22Rr2 where R is the large torroidal radius and r is the cross-section radius.The electric charge e of the lectron is the total momentum Z of the electron which is spread over area per unit volume. In equation form this is:
e = Z42ZL / 22ZL2 = 2Z / L (8)
Since h = 2PL and e = 2Z/L then:
Electric charge e, with a value of 1.6029E-19 kg/sec, is the local divergence of the aetheric field and is related to 0 and 0 as follows:
The charge of an electron, the Rydberg constant, and gravitational constant are also derivable from simple fluid mechanics1,2 treatment of the aether. See table 1, page 119, for a summary of the simple relationships of the basic atomic and electrical constants as derived using fluid mechanics and treating aether as a superfluidic particulate medium.
Analysis of the proton leads to the conclusion that it is also an aetheric torroidal vortex, rotating at velocity c, with a different radius and ring cross section3,4. The proton torroid, when it is broken up, devolves into a substructure which is made of three quarks, also torroids, which spin as a complete whole to form the proton. It is theorized that the quarks are not self-stable particles so dissipate rapidly.
8.2.1 Physics of the Torroidal Electron
When John Keely (circa 1896) first proposed the torroid structure of the nucleus, physics was just startng to get a handle on electrostatics and had only a glimmer of nuclear structure. The electron was discovered in the 19th century by J.J.Thompson in his famous water drop experiment. Since then, various models of the electron have been proposed, but up until the last 10 years none have come up with a physical model which agrees with experimental observation. The current quantum models are mathematical models, which are forced to agree with experimental evidence, but do not explain the electron's physical structure. In the previous section, I used the torroid model to show that it agreed with the charge structure. In this section, I will borrow from Bergman's excellent analysis of the torroidal structure to derive the physical parameters of the electron.
Again, the electron is assumed to be a ring with uniform current and surface charge density. The electron ring is a stable torroidal vortex made of aether rotating at the speed of light. A pictorial of the ring and its dimensions and forces is shown in figure 220.127.116.11-1 and the aether flow (i.e., the magnetic field) is shown in figure 18.104.22.168-2.
The ring has charge e (i.e., the electron charge value) and is distributed uniformly over the surface with charge density of and is moving with velocity c, the speed of light. Since the ring has no mass but is a current of electrostatic force, the ring can move at light speed without violation of mass/velocity principles. In fact, since the ring is electromagnetic, em forces move at c anyway. The area, a, of the ring is 42Rr. Thus,
e = 42Rr (11)
The energy Ee of the ring is from classical electrostatics13.
Ee = e2/2C (12)
Where C is the capacitance of the ring, the inductive or magnetostatic energy Em is also derived from classical electrostatics.
Em = Li2/2 (13)
L is the self inductance with current i of the ring. The current is also from classical electrostatics and is:
i = ec/2R (14)
It is thus seen that the electron, as a torroid ring, has both magnetic and electric fields as well as a magnetic moment caused by the ring spin. The magnetic field is shown in figure 22.214.171.124-2 and the electric field radiates from the ring in all directions. This sets up a push-pull relationship to the surrounding space. The electric field will attract or repel e-fields of like polarity and the magnetic field will do likewise for b-fields.
For a very thin ring where r << R the voltage V is computed as follows:
V = 1/(40) (e/(x2 + R2)1/2) (15)
capacitance Ce = q/V (from Sears13: "Electrostatics") but q=e so
Ce = e/V (16)
Combining 15 and 16:
Ce = 40/(x2 + R2)1/2 (17)
The inductance of the ring Le is:
Le = N/i (18)
where N is number of turns, x is the flux and i is the current. N = 1, and is:
= B x A (19)
where B is the magnetic field and A is the area.
B = 0i/2R (20)
= 0iR/2 (21)
If we assume that the energy of the capacitor Ec is equal to the Energy of the inductor EL for balanced energies in the torroid then:
Ec = e2/2Ce (22) EL = Lei2/2 (23)
From (22), (23), and (17) it is easy to show that x = 3R so combining the above:
Le = 0R/2 (24)
The frequency fe of the electron is from the familiar resonance of an LC network:
fe = 2/(LeCe) (25)
Combining (17), (22), and (23) yields:
fe = c/R (26)
From Menzel14 the Compton wavelength fc is:
fc = mc2/h (27)
where c is speed of light and h is Plank's constant. Combining (26) and (27),
R = h/mc (28)
This is the large radius, R, of the electron.
The anomalous magnetic moment can also be computed from this model of the torroidal electron. The ring current i is i = e/2 where is the angular velocity which is c so
i = ec/2R (29)
Magnetic ue is:
ue = Ai (30)
where A is the area of the current torroid. Combining (28), (29), and (30) yields:
ue = he/4m = uB (31)
where uB is the Bohr magneton. Computation of this yields:
ue = 0.92731 which is good to 3 decimal places.
The anomalous electron moment correction14 is:
(1 + /2 - 2.9732/2) = ue/u0 (32)
where is the fine structure constant and = 7.29729 x 10-3. When this correction is omputed:
ue = 0.928381
which is good to 6 places for the Bohr magneton. More accurracy can be achieved by using a better approximation for the inductance Le and the torroidal shape which is done in Bergman's analysis.
The main point to be made from all this is that the torroid electron model yields good results which are not achievable with classical or quantum mechanics. The other important point is this entire analysis obviates the need for Einstein's theories of relativity since we can derive all the atomic parameters without Einstein's nonsensical assumptions. Lets hope the orthodox community gets whth the program and wakes up.
A summary of the torroid model equations and values are shown in table 126.96.36.199-1. This table also shows the values for the positron, proton, and anti-proton. The proton is related in size by the proton mass to the electron mass ratio of 1836.15. The proton is 1836.15 times more massive than the electron so its magnetic moment, radius, rotation, and current are similarly affected. Appendix B summarizes part of the nuclides of the atomic structure as based on the torroidal particle theory.It is seen that this corresponds perfectly with known electron- and proton-measured values.
1."Space is the Absolute Reality", Dr. Parmahansa Tewari, International
Conference on Space-Time Absoluteness, Genoa, Italy, July 1982.
2.Beyond Matter,Dr.Paramahansa Tewari, Printwell Publications, 1984.
3."Detection of Stationary and Dynamic Space Substratum", Dr. Paramahansa
Tewari,Raum un Seit, Vol 2, No.1, 1990.
4."Interaction of Electron and Magnetic Field is Space Power Generation
Phenomenon", Dr. Paramahansa Tewari, Magnets In Your Future, Vol 2., No 12, December 1987.
5."Detection of Stationary and Dynamic Space Substratum", Dr.Paramahansa
Tewari,Raum un Zeit,Vol 2, no.1, 1990.
6."A Definition of Electric Charge",Paul Stowe,243 Bentley Court,American
7."The Cause of Gravity", Paul Stowe and Barry Mingst, 243 Bentley Court,
American Canyon, California, 94589, April 28, 1991.
8.Haisch, Rueda, and Puthoff, Physical Review, 1994,pages 678-694.
9."New Spinning Charged Ring Model of the Electron", David L. Bergman,
Twin-Cities Creation Conference, July 29-August 1, 1992.
10."Spinning Charged Ring Model of Elementary Particles", David L. Bergman,
Galilean Electrodynamics, March/April 1991.
11."APhysical Model for Atoms and Nuclei", Joseph Lucas, Galilean
12."Physical Models for Elementary Particles, Atoms and Nuclei", David L.
Bergman and Charles Wm. Lucas, Jr., IV International Conference: Problems of
Space, Time & Motion, Saint Petersbburg Russia, September 23-29, 1996.
13.Electricity and Magnetism, Francis Weston Sears, Addison-Wesley Publishing
Company,Reading Mass., 1946.
14.Fundamental Formulas of Physics, Donald H. Menzel, Dover Publication, Inc., 1960.
Link:The Neutral Center and the Aether Spectrum (200701051916) | <urn:uuid:3088d6f3-5f27-466c-840e-47453c7fa6db> | 3.71875 | 4,046 | Academic Writing | Science & Tech. | 57.77064 | 95,586,323 |
The First Detection of Gravitational Waves
Institute of Mathematics of Polish Academy of Sciences, Śniadeckich 8, 00-656 Warsaw, Poland (for the LIGO Scientific Collaboration and the Virgo Collaboration)
Author to whom correspondence should be addressed.
Received: 15 June 2017 / Revised: 23 July 2017 / Accepted: 25 July 2017 / Published: 31 July 2017
This article deals with the first detection of gravitational waves by the advanced Laser Interferometer Gravitational Wave Observatory (LIGO) detectors on 14 September 2015, where the signal was generated by two stellar mass black holes with masses 36
that merged to form a 62
black hole, releasing 3
energy in gravitational waves, almost 1.3 billion years ago. We begin by providing a brief overview of gravitational waves, their sources and the gravitational wave detectors. We then describe in detail the first detection of gravitational waves from a binary black hole merger. We then comment on the electromagnetic follow up of the detection event with various telescopes. Finally, we conclude with the discussion on the tests of gravity and fundamental physics with the first gravitational wave detection event.
This is an open access article distributed under the Creative Commons Attribution License
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
Share & Cite This Article
MDPI and ACS Style
Królak, A.; Patil, M. The First Detection of Gravitational Waves. Universe 2017, 3, 59.
Królak A, Patil M. The First Detection of Gravitational Waves. Universe. 2017; 3(3):59.
Królak, Andrzej; Patil, Mandar. 2017. "The First Detection of Gravitational Waves." Universe 3, no. 3: 59.
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Apple’s Swift is a powerful, beginner-friendly programming language that anyone can use to make cool apps for the iPhone or iPad. In Coding iPhone Apps for Kids, you’ll learn how to use Swift to write programs, even if you’ve never programmed before.
You’ll work in the Xcode playground, an interactive environment where you can play with your code and see the results of your work immediately! You’ll learn the fundamentals of programming too, like how to store data in arrays, use conditional statements to make decisions, and create functions to organize your code—all with the help of clear and patient explanations.
Once you master the basics, you’ll build a birthday tracker app so that you won’t forget anyone’s birthday and a platform game called Schoolhouse Skateboarder with animation, jumps, and more!
As you begin your programming adventure, you’ll learn how to:
–Build programs to save you time, like one that invites all of your friends to a party with just the click of a button!
–Program a number-guessing game with loops to make the computer keep guessing until it gets the right answer
–Make a real, playable game with graphics and sound effects using SpriteKit
–Challenge players by speeding up your game and adding a high-score systemWhy should serious adults have all the fun? Coding iPhone Apps for Kids is your ticket to the exciting world of computer programming.
Covers Swift 3.x and Xcode 8.x. Requires OS X 10.11 or higher.Create an app that reminds you to wish your friends a happy birthday
Write a function to automatically write customized party invitations!
Program a number guessing game with while loops
Make a sidescrolling skateboard action game with SpriteKit
Book for learning how to use Swift, Apple’s popular iOS programming language, to create exciting apps | <urn:uuid:fd5e9602-198f-4cde-9353-fac5b92deea2> | 2.953125 | 426 | Product Page | Software Dev. | 56.140265 | 95,586,334 |
Beggiatoa is a genus of bacteria in the order Thiotrichales. They are named after the Italian medic and botanist F. S. Beggiato. The organisms live in sulfur-rich environments. During his research in Anton de Bary’s laboratory of botany in 1887, Russian botanist Sergei Winogradsky found that Beggiatoa oxidized hydrogen sulfide (H2S) as an energy source, forming intracellular sulfur droplets. Winogradsky referred to this form of metabolism as inorgoxidation (oxidation of inorganic compounds). The finding represented the first discovery of lithotrophy. Two species of Beggiatoa have been formally described: the type species Beggiatoa alba, and Beggiatoa leptomitoformis, the latter of which was only published in 2017.
Beggiatoa can be found in marine or freshwater environments. They can usually be found in habitats that have high levels of hydrogen sulfide. These environments include cold seeps, sulfur springs, sewage contaminated water, mud layers of lakes, and near deep hydrothermal vents. Beggiatoa can also be found in the rhizosphere of swamp plants.
The colorless cells are disk-shaped or cylindrical, arranged in long filaments with a cell diameter that can measure between 12 and 160 micrometres (different subspecies). A massive central vacuole is used for accumulation of nitrate, presumably for use as an electron acceptor in anaerobic sulfide oxidation. The filaments are surrounded by slime and can move by gliding.
Beggiatoa can grow chemoorgano-heterotrophically by oxidizing organic compounds to carbon dioxide in the presence of oxygen, although high concentrations of oxygen can be a limiting factor. Organic compounds are also the carbon source for biosynthesis. Some species may oxidize hydrogen sulfide to elemental sulfur as a supplemental source of energy (facultatively litho-heterotroph). Produced sulfur is stored intracellularly.
Some species have the ability of chemolitho-autotrophic growth by means of sulfide oxidation for energy and with carbon dioxide as a source of carbon for biosynthesis. In this metabolism internal stored nitrate is the electron acceptor and reduced to ammonia.
- Sulfide oxidation: 2H2S + O2 → 2S + 2H2O
Marine autotrophic Beggiatoa species are able to oxidize intracellular sulfur to sulfate.
A frequently occurring mechanism when oxygen is lacking is reduction of elemental sulfur. Sulfur is reduced to sulfide at the cost of stored carbon or by added hydrogen gas. This may be a survival strategy to bridge periods without oxygen.
Filaments have been observed to form dense mats on sediments in estuarine, shelf, seep, and deep-sea hydrothermal vent environments. They appear as a whitish layer and since they are present and flourish in marine environments which have been subject to pollution, they can be considered as an indicator species.
Beggiatoa and other related filamentous bacteria can cause settling problems in sewage treatment plants, industrial waste lagoons in canning, paper pulping, brewing, milling, causing the phenomenon called "bulking". Beggiatoa are also able to detoxify hydrogen sulfide in soil.
- Roxanne L. Nikolaus "Beggiatoa and hydrocarbon seeps - Unique bacteria thriving in a unique environment".
- Trevisan, V. 1842. Prospetto della Flora Euganea. Coi Tipi Del Seminario, Padova, pp. 1-68.
- Parte, A.C. "Beggiatoa". www.bacterio.net.
- Ljungdahl LG (2003). Biochemistry and physiology of anaerobic bacteria. Springer. p. 17. ISBN 978-0-387-95592-6.
- Mukhopadhyaya PN, Deb C, Lahiri C, Roy P (Aug 2000). "A soxA gene, encoding a diheme cytochrome c, and a sox locus, essential for sulfur oxidation in a new sulfur lithotrophic bacterium". J Bacteriol. 182 (15): 4278–87. doi:10.1128/JB.182.15.4278-4287.2000. PMC . PMID 10894738.
- Parte, A.C. "Beggiatoa". www.bacterio.net. Retrieved 2017-10-18.
- Ahmad A, Barry JP, Nelson DC (Jan 1999). "Phylogenetic affinity of a wide, vacuolate, nitrate-accumulating Beggiatoa sp. from Monterey Canyon, California, with Thioploca spp". Appl Environ Microbiol. 65 (1): 270–7. PMC . PMID 9872789.
- Michael Dudley. "Beggiatoa".
- Schmidt TM, Arieli B, Cohen Y, Padan E, Strohl WR (Dec 1987). "Sulfur metabolism in Beggiatoa alba". J Bacteriol. 169 (12): 5466–72. PMC . PMID 3316186. | <urn:uuid:94115d36-50f6-445d-ab2a-937fee76ae0b> | 3.84375 | 1,121 | Knowledge Article | Science & Tech. | 42.665742 | 95,586,342 |
The earth can be considered from a “material” point of view as a closed system, there being practically no exchange of material with external sources. However, this is not the case when considering “energy.” The earth is continually subject to energy exchanges with the solar system, namely energy from the sun impinges on the earth’s surface and is partially reflected.
KeywordsDraft Tube Hydropower Station Francis Turbine Machine Unit Hydropower Potential
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Extended zeta functions make it possible to prove or dis-prove Riemann's Hypothesis More
While extended zeta functions support investigations of Riemann's hypothesis and estimates for the Prime Number Theorem, some zeta functions offer better prospects for providing easy proofs, or disproofs. In 1859, Riemann had the idea to define Euler’s function ε(x)=∑m^x for all complex numbers s=x+iy by analytic extension. This extension is important in number theory and plays a central role in the distribution of prime numbers. There are a number of ways of extending Euler's zeta function ζ(s) to points where 0≤x≤1. Because ζ(s) is an alternating series, it becomes possible to prove or disprove Riemann's Hypothesis.
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Carbon dating explained for kids Gratis seks chat usa
However, cosmic radiation constantly collides with atoms in the upper atmosphere.Part of the result of these collisions is the production of radiocarbon (C, pronounced "c fourteen"), carbon atoms which are chemically the same as stable carbon, but have two extra neutrons.All living things on Earth are made up of a high percentage of an element called carbon.
(This, in turn, is caused by variations in the magnetic fields of the earth and sun, for example.) Although the ratio of radiocarbon to stable carbon in the atmosphere has varied over time, it is quite uniform around the globe at any given time because the atmosphere mixes very quickly and constantly.
[See Periodic Table of the Elements] Carbon occurs naturally as carbon-12, which makes up almost 99 percent of the carbon in the universe; carbon-13, which makes up about 1 percent; and carbon-14, which makes up a minuscule amount of overall carbon but is very important in dating organic objects.
Just the facts Carbon: From stars to life As the sixth-most abundant element in the universe, carbon forms in the belly of stars in a reaction called the triple-alpha process, according to the Swinburne Center for Astrophysics and Supercomputing.
Carbon 14 has a half-life of 5,780 years, and is continuously created in Earth's atmosphere through the interaction of nitrogen and gamma rays from outer space.
Because atmospheric carbon 14 arises at about the same rate that the atom decays, Earth's levels of carbon 14 have remained fairly constant. We are currently updating our website to reflect EPA's priorities under the leadership of President Trump and Administrator Pruitt. | <urn:uuid:1260dd5a-f1ff-47da-8608-c2a22923e6fc> | 3.546875 | 354 | Knowledge Article | Science & Tech. | 34.045161 | 95,586,379 |
Python 2.1.1 (#1, Dec 29 2004, 11:06:29)
[GCC 3.3.3] on linux2
Type "copyright", "credits" or "license" for more information.
>>> # First we need to import smtplib, which we use for sending email
>>> import smtplib
>>> # Next we compose the message we want to be sent, in MIME format.
>>> # You can go ahead and include attachments or whatever.
>>> # One quick way would be to use MS Outlook or something to compose
>>> # the message, then save it as .eml, and copy the source.
>>> # Note here that "From:", "To:", "Cc:" etc are what your recipients
>>> # will see in the header, but does not reflect on who the message is
>>> # actually from, or is actually sent to.
>>> # The message only goes to people who you specify in the sendmail() call.
>>> # Note also that the \r\n pattern should separate each field in the header
>>> # and the \r\n\r\n separates header from the body.
>>> message = """From: John Dove <firstname.lastname@example.org>\r\nTo: John Dove <email@example.com>\r\nCc: Jane Dove <firstname.lastname@example.org>\r\nSubject: Hi!\r\n\r\n
... Hi John,
... How are you doing man?
... Just mailing in to let you know that I exist..
... Just woke up when you were loitering around in the pantry :D
... /your alter-ego(2)
>>> # Now we initiate the smtp connection
>>> mailServer = smtplib.SMTP("smtp.server.com")
>>> # Now we actually send the email..
>>> mailServer.sendmail("email@example.com", ["firstname.lastname@example.org",
... "email@example.com", "firstname.lastname@example.org"], message);
>>> # Now that we are done, we 'hang up' the connection
>>> # bbye :D | <urn:uuid:d51855cd-f819-4142-a42e-ea10808b9646> | 2.71875 | 494 | Personal Blog | Software Dev. | 81.843999 | 95,586,382 |
Part of the Text and Monographs in Computer Science book series (MCS)
In an array all elements are of the same type. In contrast to the array, the record structure offers the possibility to declare a collection of elements as a unit even if the elements are of different types. The following examples are typical cases where the record is the appropriate choice of structuring method. A date consists of three elements, namely day, month, and year. A description of a person may consist of the person’s names, sex, identification number, and birthdate. This is expressed by the following type declarations
Date = RECORD day: [1.. 31];
Person = RECORD
firstName, lastName: ARRAY [0.. 31] OF CHAR;
KeywordsStatement Sequence Array Element Record Type Record Field Individual Field
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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Have you ever wondered about what causes the distinct smells you detect in the air before, during and after a rainfall? Scientists say it’s a combination of ozone, petrichor and geosmin.
Before it rains, a person might say that they can smell the storm coming. Their nostrils might be picking up the scent of ozone, or O3. Ozone is a naturally present gas in the atmosphere that gets its name from the Greek word, “ozein,” which means “smell,” according to the National Oceanic and Atmospheric Administration.
The pleasant scent that fills the air during a rainfall as raindrops come into contact with the ground is called petrichor, and the term was coined by Australian scientists Isabel Joy Bear and Richard Thomas in 1964.
“Petrichor is caused by oils derived from plants, primarily leaves, that accumulate over dry periods,” said Jeff Weber, a meteorologist with the University Corporation for Atmospheric Research Unidata Program Center.
“These oils settle into soils or onto pavement over time and are released into the atmosphere by being disturbed by rainfall,” Weber said.
The smell of petrichor has been described in a variety of ways, including earthy, musky and fresh, and tends to be stronger after a lengthy period of no rainfall, he added.
This is due to the fact that plant oils accumulate over time, which makes petrichor more pronounced after a dry period.
Researchers believe that the oils released by petrichor inhibit seed germination, and that the oils serve to help reduce competition from other plants for scarce water supplies.
The soil-dwelling oils that produce petrichor also compound with the smells of other organisms, according to Michelle Pettit, a climate and sustainability specialist for Just Energy, a natural gas and green energy provider.
“Bacteria called actinomycetes, which live in soil, produce spores during this dry time,” Pettit said.
“Their spore production includes the chemical geosmin, and when the rain sends the spores up into the air, it releases the smell of geosmin,” she added.
Geosmin, which is created by the dying off of microorganisms in the soil, is the distinctively earthy smell often associated with rain. It tends to smell strongest when it's been raining for a longer period of time, Pettit said.
“However, some people's noses can detect geosmin when there's even a small amount of moisture in the soil,” she added.
Geosmin bacteria aid in the decomposition of organic materials, according to Weber. Petrichor and geosmin occur as a result of the interaction with water and the subsequent release of aerosolized compounds, Weber said.
In 2015, researchers observed via high-speed cameras that raindrops release clouds of aerosols upon impact with a surface.
Researchers believe that these aerosols may carry aromatic elements in natural environments, and can be released and spread with the help of rainfall and wind gusts, according to the Massachusetts Institute of Technology.
Comments that don't add to the conversation may be automatically or manually removed by Facebook or AccuWeather. Profanity, personal attacks, and spam will not be tolerated.
The threat for damaging thunderstorms will shift into the southeastern United States as the weekend kicks off.
Three people were injured after severe weather tore from Indiana to Kentucky and Tennessee to end the week.
A new round of severe weather is threatening lives from Ohio through Tennessee and will continue into Saturday morning.
In select regions of the world, people can live long enough to make some wonder if these countries have discovered the heavily sought-after fountain of youth.
A town in Iowa was severely damaged by a tornado on Thursday, while strong storms led to a tour boat disaster in Missouri that killed 17.
A boat carrying 31 people capsized on a lake near Branson, Missouri, as thunderstorms moved through the area on Thursday evening.
The risk of severe thunderstorms, including isolated tornadoes, will progress farther to the east and south over the central United States into Friday night. | <urn:uuid:509ec8b2-3969-4cfa-946c-da93319f29bb> | 3.515625 | 869 | Truncated | Science & Tech. | 37.865 | 95,586,440 |
|Periods of inactivity are normal for the sun, but this period has gone on longer than usual. (Photo courtesy of NASA).|
That's good news for people who scramble when space weather interferes with their technology, but it became a point of discussion for the scientists who attended an international solar conference at Montana State University. Approximately 100 scientists from Europe, Asia, Latin America, Africa and North America gathered June 1-6 to talk about "Solar Variability, Earth's Climate and the Space Environment."
The scientists said periods of inactivity are normal for the sun, but this period has gone on longer than usual.
"It continues to be dead," said Saku Tsuneta with the National Astronomical Observatory of Japan, program manager for the Hinode solar mission. "That's a small concern, a very small concern."
The Hinode satellite is a Japanese mission with the United States and United Kingdom as partners. The satellite carries three telescopes that together show how changes on the sun's surface spread through the solar atmosphere. MSU researchers are among those operating the X-ray telescope. The satellite orbits 431 miles above ground, crossing both poles and making one lap every 95 minutes, giving Hinode an uninterrupted view of the sun for several months out of the year.
Dana Longcope, a solar physicist at MSU, said the sun usually operates on an 11-year cycle with maximum activity occurring in the middle of the cycle. Minimum activity generally occurs as the cycles change. Solar activity refers to phenomena like sunspots, solar flares and solar eruptions. Together, they create the weather than can disrupt satellites in space and technology on earth.
The last cycle reached its peak in 2001 and is believed to be just ending now, Longcope said. The next cycle is just beginning and is expected to reach its peak sometime around 2012. Today's sun, however, is as inactive as it was two years ago, and scientists aren't sure why.
"It's a dead face," Tsuneta said of the sun's appearance.
Tsuneta said solar physicists aren't like weather forecasters; They can't predict the future. They do have the ability to observe, however, and they have observed a longer-than-normal period of solar inactivity. In the past, they observed that the sun once went 50 years without producing sunspots. That period coincided with a little ice age on Earth that lasted from 1650 to 1700.
Tsuneta said he doesn't know how long the sun will continue to be inactive, but scientists associated with the Hinode mission are ready for it to resume maximum activity. They have added extra ground stations to pick up signals from Hinode in case solar activity interferes with instruments at other stations around the world. The new stations, ready to start operating this summer, are located in India, Norway, Alaska and the South Pole.
Establishing those stations, as well as the Hinode mission, required international cooperation, Tsuneta said. No one country had the resources to carry out those projects by itself.
Four countries, three space agencies and 11 organizations worked together on Hinode which was launched in September 2006, Tsuneta said. Among the collaborators was Loren Acton, a research professor of physics at MSU. Tsuneta and Acton worked together closely from 1986-2002 and were reunited at the MSU conference.
"His leadership was immense, superb," Tsuneta said about Acton.
Acton, 72, said he is still enthused by solar physics and the new questions being raised. In fact, he wished he could knock 22 years off his age and extend his career even longer.
"It's too much fun," he said. "There's so much exciting stuff come up, I would like to be part of it."
A related article on the Hinode mission is located at http://www.montana.edu/cpa/news/nwview.php?article=4902
Evelyn Boswell, (406) 994-5135 or firstname.lastname@example.org | <urn:uuid:e73862c9-0279-4aed-8ab2-aa6a1b4eaae5> | 3.296875 | 850 | News Article | Science & Tech. | 46.531708 | 95,586,447 |
Well then, are they or are they not?
I chose "other".
"alive" must first be defined to accurately reply to this question.
Do viruses have hereditary material? That is a common definition of "alive".
Yes exactly, what defines "alive".
Viruses are what they are. If alive is just being able to reproduce, then viruses are alive. If alive means consuming energy and being proactive (IE growth, movement) then nope, not alive
Often the debates about wether a virus is alive or not is really a debate about what constitutes "alive", without the participants even knowing it
Alive involves movement, metabolism and reproduction. One-celled animals like prokariotes do these things on their own. Viruses have no metabolism and their reproduction depends on the structures of the cells they prey upon. Some of them do move independently.
So I put NOT. The other category seems a cop-out; clearly even very simple bacteria are alive, and also clearly viruses don't do - independently - all the things a linving organism is assumed to.
What he said . . . no way.
It's a bit of programming that can take advantage of a living cell.
Some people have theorized that viruses were developed by some ancient form of bacteria as a weapon against other bacteria. I don't know the current scientific validity of that theory, but it makes sense. Something living (and with RNA at least) had to make the first virus, since it couldn't have made itself. If you don't believe that a bullet or a missile is alive, then neither is a virus.
You know they're alive after you've lived with a couple for a few years.
Of course, this assumtion would imply that all windows computers are alive. So that won't work dagit!
Interesting idea, sort of like venom. Looking at it on the constructive side, I have wondered if viruses might be genetic remnants left over from early single cell diversification.
if you can tell me a usefull purpose, reason for knowing i'll think about it.
otherwise, i don't care.
olde, it's interesting to see that the definition of "life" has some questions in it, contrqry to what might naively be presumed. It's always good to ground a high flying discussion in the real world, don't you think?
the world is full of impounderables. i'll invest time and energy with those that either expand my awareness or improve my life.
a pragmatic seeker? guilty!
"dead or alive"
Why not; is anything dead.
Or do things just change there physical states?
How much much more "dead or alive" is that oxigen molecule, that the "dead or alive" virus swallowed?
The question poses too much definition in terms, I suppose. No one here is going to agree 100% of what alive, dead, or neither actually consists and constitutes of.
There is general consensus that life is a self-sustaining sytem that metabolizes, multiplies, and has the ability to evolve. Because technically it can be said that a fire, for example, metabolizes and multiplies, I like the delimiter John Maynard Smith and Eors Szathmanry gave in their book "The Origins of Life." They said we might define as living ". . . any population of entities possessing those properties that are needed if the population is to evolve by natural selection. That is, entities are alive if they have the properties of multiplication, variation, and heredity (or are descended from such entities; a mule cannot multiply, but its parents did). . . . Why should we regard these three particular porperties as defining life? It is because they are necessary if a population is to evolve all the other characteristic we associate with life."
A virus, by even less of a definition than that, fails to show it is alive. Left on its own, it will not multipy, it will not variate (constructively), and of course it will not pass on genetic material. It can do nothing until it enters a living system, which then merely reproduces the virus and reacts to the virus. True, the virus can mutate, but it can only do that once it enters the living system. Remember, the genetic material of a virus came from formerly living cells, so we shouldn't be surprised that programmed into it is an adaptive trigger. Because a virus cannot mutate on its own, we have to assume it is the living system itself which is providing the impetus to pull that trigger.
A virus is not alive!
Viruses are biological uncertainty.
In biology, the only certainties are death and taxis.
Shh! Redefine the question, if you want, to include the phrase: According to your personal concept of life...
You see, I have a problem with this argument. Nothing does all the things a living organism is presumed to, independently. Plants need sunlight, for example. Humans need to eat. Animals usually need females, or males. Why can't we say that viruses are living carnivores, which feed on uninfected cells and digest them to function?
I think that virus must have de-evolved from a bacteria that was alive but for whatever reason became a parasite. How else could a virus come about or develop without life to make its DNA. It does not seem possible that it could be proto-life or a simpler form of life without more complex and complete life to prey on and to make its DNA or RNA whichever it is. Virus do adopt and become resistant but how they do this is a puzzle to me. How do they trick the host cell to change its RNA to overcome the host's defenses?
Actually, your examples easily fall into the categories of metabolism and reproduction, and so do not stray from "the things a living organism is presumed" to do independently.
We can say viruses "feed on uninfected cells and digest them to function," but so does a fire feed on wood, for instance, to function. Lots of things operate that way. That is why life requires more than just metabolism or reproduction to be defined properly.
The virus seems to me to operate exactly like programming does. Software just sits there until you insert it into the "living" (i.e., powered) system of a computer. What is the problem with differentiating between programming and the powered system?
Very funny Loren. I hate to encourage such pun-ishing contributions, but . . . how do you explain life's relentless, less-than-Checkered march toward adaptive-taxis while viruses are content to sit there "exempt" from change for eternity?
I'd say the virus is no more alive than the weather in the sense that it is a natural system. It really is an oddity of evolution in that way.
If you've ever seen that movie the Andromeda strain it shows how something can evolve without necessarily being alive.
Evolution is a completely natural process like the weather.
L W Sleeth
Think of the permanent stasis of viruses as occupying an otherwise unfulfilled niche. Also, not wasting energy on metabolism for processes like active motility can prove most efficient. One may thus think of a virus as utilizing statistically random currents to navigate its environment.
I agree. But, I heard viruses are more complicated than chemical molecules. Meaning, that it is much simplier than the most basic single cell organism. Virusues are very similar to organisms, viruses are made up of proteins and nucleic acid which are organic compounds. Some viruses have a lipid membrane, too. They evolve and mutate. A virus has the potential to reproduce with the aid of their host cell, but does not need energy to persist. So you can say it reproduces using another type of organism. Just like humans need "something else, a mate" to reproduce.
As I said, no one here is going to agree 100% on what life consists of exactly. So far.
In summation, I think you can safely say that [virusues] because they require the metabolic machinery of host cells to survive, and contain genetic material, you can say they both have living and nonliving characteristics.
The problem, obviously, is how we are going to define "alive."
We wouldn't have this debate about bacteria because it's clear they are a self-contained system which metabolizes, reproduces, and passes on hereditary information to their offspring. Even the primitive prokaryote has a huge range of metabolic patterns and is mobile, while viruses rely almost entirely on the enzymic machinery and metabolite supply of the hosts cells. As Gould put it, "Viruses certainly do not grow, and they feed only if we greatly expand our definition of feeding. In fact, they exist only because they can replicate . . ."
Everything I've read (which I have to rely on since I've not personally observed viruses, plasmids, or phages) gives me the impression viruses are zombies, soulless bits of capsid-bound RNA or DNA lacking any vitality whatsoever.
Using the words "soul" and "vitality" are controversial things to say, yet this debate might ultimately be about whether life is an inherent force or if it is merely the functions of chemical machinery. Some people want to call a virus alive because they are of the latter opinion, and of course some people of the former opinion don't see the virus as alive. So we are stuck at the point of defining what life is.
Personally, I can't even get myself to call a virus degenerate life. I think it is a dead piece of programming animated by living forms, and that to call it alive, we have to redefine what life has meant. If the science world gets to make that decision, and they decide to classify a virus as life, then I will still maintain in my own mind at least another category for beings which seem vitalized.
The thing is, the aspect of "aliveness" doesn't show up until a virus enters a host everyone agrees is "alive." Isn't that suspicious?
So, what most defines "aliveness"? Is it the machinery of a biological form or is it the dynamism? Even the simple, organelle-less prokayote exhibits dynamism. In fact, when we observe a "dead" thing, we see all the machinery is present, but it has lost its dynamic-ness. Even if we agree that it's the machinery alone which produces that dynamism, it's loss nonetheless makes the thing dead (and a living being's dynamism can endure through the failure or loss of a great many machine parts too).
That's why I can't see what to make of the lack of dynamism in a virus except that it isn't alive itself, and is only animated by something that is alive. I suppose someone might argue that the virus is made alive by its host, but to me then we have to include my bicycle as alive while I ride it.
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News Aug 25, 2015
Want to see where a particular gene is active? Use green fluorescent protein, or GFP, and the cells will light up.
Want to turn that gene on or off in an organism? You might use an enzyme called Cre recombinase.
Want to turn a gene on or off only in one cell type? That’s tough.
But the job just got a lot easier: Harvard Medical School researchers have found a way to combine GFP and Cre.
The new tool, called “Cre dependent on GFP” or Cre-DOG for short, piggybacks Cre onto GFP so researchers can not only look at but also manipulate genes in GFP-expressing cells while leaving other cells alone.
“In one step you can go from just looking at a cell to asking something about its physiology, its circuitry and its anatomy. That’s very powerful,” said Connie Cepko, the Bullard Professor of Genetics and Neuroscience at HMS and senior author of the study.
Over a thousand transgenic mouse lines have been engineered to express GFP in particular kinds of cells, while there are far fewer Cre lines. Cre-DOG allows researchers to skip the laborious creation of Cre lines by doing more with existing GFP lines.
“It opens up genetic manipulations in a much larger number of specific cell types and saves a huge amount of time and money,” said Cepko. “The more we know about how cells function, the better we can understand disease and development, allowing us to design more effective therapies.”
“In our lab we have a lot of mouse lines that express GFP, but so far, we only use them for anatomical studies. Now we can use them to study circuit function and development in the brain, define the roles of subpopulations of neurons within a circuit and study which neurotransmitters they release,” said Stephanie Rudolph, a postdoctoral researcher in the lab of HMS neurobiologist Wade Regehr and second author of the paper.
Cre-DOG was the brainchild of Jonathan C.Y. Tang, a postdoctoral researcher in the Cepko lab and first author of the paper.
Tang split the Cre enzyme in two, which inactivated it. He attached each half to a portion of a GFP antibody that had recently been generated through the immunization of camels.
When the Cre-and-antibody fragments are introduced into cells that don’t express GFP, they float around and don’t do much. But when they’re added to cells that do express GFP, the antibodies latch onto GFP and the Cre halves reunite. The newly activated Cre then turns the desired gene on or off.
Cre-DOG expanded on a similar tool that Tang and colleagues reported in 2013. That tool requires an extra component to generate Cre activity and may be more toxic than Cre-DOG. Both tools have their advantages, the authors said, and researchers might want to use one over the other depending on their project.
One perk of Cre-DOG is that the Cre-and-antibody molecules can be injected using adeno-associated viruses, or AAVs, a tool many researchers already use.
“From the standpoint of a mentor, it’s really wonderful to see a student come in with a very cool and clever idea and bring it to fruition,” said Cepko. “There is also pleasure in making tools that move all of us forward.”
Tang and Cepko collaborated with researchers at HMS, including the Regehr lab and the lab of David Ginty in the Department of Neurobiology, as well as scientists at the University of California, San Diego, to test Cre-DOG in different kinds of cells. They were able to show that it works in the retina, the cortex and the spinal cord.
“I think every human being wants to understand how the brain works,” added Tang. “We are at the forefront of that endeavor, but we still don’t have all the tools. This work expands our arsenal of genetic tools to study that question.”
Identical Twin Study Shows Impact of a Lifetime of Exercise on FItnessNews
When it comes to being fit, are genes or lifestyle more important? Researchers removed the nature part of the equation by studying a pair of identical twins who had taken radically different fitness paths over three decades. One became an Ironman triathlete while the other remained relatively sedentary over the last 30 years. | <urn:uuid:8b80078e-684c-4c6c-b321-7cfdc1411bfb> | 3.265625 | 958 | News Article | Science & Tech. | 52.281545 | 95,586,478 |
Beyond velocity and acceleration: Jerk, snap and higher derivatives
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- European Journal of Physics, 2016, 37 (6)
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� 2016 IOP Publishing Ltd. The higher derivatives of motion are rarely discussed in the teaching of classical mechanics of rigid bodies; nevertheless, we experience the effect not only of acceleration, but also of jerk and snap. In this paper we will discuss the third and higher order derivatives of displacement with respect to time, using the trampolines and theme park roller coasters to illustrate this concept. We will also discuss the effects on the human body of different types of acceleration, jerk, snap and higher derivatives, and how they can be used in physics education to further enhance the learning and thus the understanding of classical mechanics concepts.
Please use this identifier to cite or link to this item: | <urn:uuid:40071f2e-20d7-481a-94d9-72c5edd28c1e> | 2.78125 | 251 | Truncated | Science & Tech. | 33.577746 | 95,586,485 |
Sliding Block Puzzle
This program currently provides an envoronment for runnning a sliding block puzzle for CS 380.
A profile of how many nodes are explored, how much time does the search take, and
the length of the solution found is availble in
output-part3 for levels 0-3. The
reamining levels are not included because the algroithmntook too much time to run
after level 3.
g++compiler that supports the C++11 standard
To build, simply run
This uses g++ to compile the main script with the
-std flag set to
These are the executables built that can be used to find solutions. To run any of them, use make with the first argument as the shortened name for it and an optional states file as the STATES flag. By default, the STATES flag is states/SBP-level0.txt.
Breadth First Search
$ make bfs STATE=states/SBP-level0.txt
Depth First Search
$ make dfs STATE=states/SBP-level0.txt
Iterative Deepening Search
$ make ids STATE=states/SBP-level0.txt
Two heuristics are provided for A*.
$ make manhattan STATE=states/SBP-level0.txt
This is the custom heuristic implemented for A*.
This heuristic works by taking the manhattan distance, and adding an extra cost if a piece is blocking the goal. If a piece is in the way of the goal, 1 is added to the cost, 0 otherwise. The reasoning behind this is that we encourage states that have no other piece blocking the goal to be searched since they may take fewer moves to find a solution. This heuristic is also admissible since the fewest possible number of moves required to reach the goal is the optimal one carried over by the manhattan distance.
$ make blockage STATE=states/SBP-level0.txt
A dry run of both A* heuristics can be performed with
$ make run
This will print how many nodes are explored, how much time does the search take,
and the length of the solution found in a file called
This file should already be provided in this repo.
The reamining levels are not included because the algroithmntook too much time to run
after level 3. | <urn:uuid:d36429af-5fda-4ab5-aa11-77803bc22bc0> | 2.578125 | 502 | Documentation | Software Dev. | 61.293874 | 95,586,510 |
Resinous, long-lived, monoecious evergreen trees, of strongly monopodial habit. Trunk simple, erect, columnar. Branchlets composed of ± scattered short shoots borne laterally from long, principal shoots, with short shoots sometimes giving rise to long shoots, each with conspicuous annual growth increments and terminal resting buds. Leaves spirally arranged, flattened, simple, oblong-linear, present on seedlings but evanescent and becoming rapidly modified into small, deltoid, dry, scale-like spurs present thereafter throughout the vegetative axes of adult plants, distant, deciduous, transient, and without axillary appendages on long proximal portions of each annual increment of shoot, becoming crowded, woody, and basally persistent on the broadened, short distal, terminal portions of each annual increment of shoot, where each bears a single axillary phylloclade; the phylloclades functionally replacing the leaves of plants subsequent to the seedling stage, linear, persisting only a few years, arising distally either on long principal or short lateral shoots in discrete spreading, tightly-spiralled false whorls, each whorl separated from those of previous year’s by conspicuous bare lengths of shoot with persistent knoblike bases of true leaves. Male cones subglobose and subsessile, aggregated into densely compacted, crowded, terminal, raceme-like clusters of 5–10 or more at the tips of short or long shoots. Female (ovuliferous) cones solitary, usually near the ends of branches of previous year’s shoots, each with numerous, tightly and spirally arranged, broad, fibrous, wedge-shaped scales widening outwards, smaller than their subtending bract scales at first, but later outgrowing the bracts, bearing 7–9, transversely arranged, anatropous ovules. Seeds ovate-elliptic, large, with a very narrow wing. Cotyledons 2.
KeywordsPollen Morphology Wood Anatomy Short Shoot Seed Scale Zealand Species
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Today, researchers who found the first hypervelocity stars escaping the Milky Way announced that their search also turned up a dozen double-star systems. Half of those are merging and might explode as supernovae in the astronomically near future.
All of the newfound binary stars consist of two white dwarfs. A white dwarf is the hot, dead core left over when a sun-like star gently puffs off its outer layers as it dies. A white dwarf is incredibly dense, packing as much as a sun's worth of material into a sphere the size of Earth. A teaspoon of it would weigh more than a ton.
"These are weird systems - objects the size of the Earth orbiting each other at a distance less than the radius of the Sun," said Smithsonian astronomer Warren Brown, lead author of the two papers reporting the find.
The white dwarfs found in this survey are lightweight among white dwarfs, holding only about one-fifth as much mass as the Sun. They are made almost entirely of helium, unlike normal white dwarfs made of carbon and oxygen.
"These white dwarfs have gone through a dramatic weight loss program," said Carlos Allende Prieto, an astronomer at the Instituto de Astrofisica de Canarias in Spain and a co-author of the study. "These stars are in such close orbits that tidal forces, like those swaying the oceans on Earth, led to huge mass losses."
Remarkably, because they whirl around so close to each other, the white dwarfs stir the space-time continuum, creating expanding ripples known as gravitational waves. Those waves carry away orbital energy, causing the stars to spiral closer together. Half of the systems are expected to merge eventually. The tightest binary, orbiting once every hour, will merge in about 100 million years.
"We have tripled the number of known, merging white-dwarf systems," said Smithsonian astronomer and co-author Mukremin Kilic. "Now, we can begin to understand how these systems form and what they may become in the near future."
When two white dwarfs merge, their combined mass can exceed a tipping point, causing them to detonate and explode as a Type Ia supernova. Brown and his colleagues suggest that the merging binaries they have discovered might be one source of underluminous supernovae -- a rare type of supernova explosion 100 times fainter than a normal Type Ia supernova, which ejects only one-fifth as much matter.
"The rate at which our white dwarfs are merging is the same as the rate of underluminous supernovae - about one every 2,000 years," explained Brown. "While we can't know for sure whether our merging white dwarfs will explode as underluminous supernovae, the fact that the rates are the same is highly suggestive."
The papers announcing their find are available online at: http://arxiv.org/abs/1011.3047 and http://arxiv.org/abs/1011.3050. Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.
For more information, contact:David A. Aguilar
Christine Pulliam | EurekAlert!
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