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Run-Time Abstraction Services ( RTAS ) is run-time firmware that provides abstraction to the operating systems running on IBM System i and IBM System p computers.
It contrasts with Open Firmware , in that the latter is usually used only during boot, while RTAS is used during run-time.
Later it was renamed to Open Power Abstraction Layer ( OPAL ), and it's stored in a PNOR (platform NOR) flash memory.
This computing article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Run-Time_Abstraction_Services |
A run-around coil is a type of energy recovery heat exchanger most often positioned within the supply and exhaust air streams of an air handling system, or in the exhaust gases of an industrial process, to recover the heat energy. Generally, it refers to any intermediate stream used to transfer heat between two streams that are not directly connected for reasons of safety or practicality. It may also be referred to as a run-around loop , a pump-around coil or a liquid coupled heat exchanger . [ 1 ]
A typical run-around coil system comprises two or more multi-row finned tube coils connected to each other by a pumped pipework circuit. The pipework is charged with a heat exchange fluid, normally water, which picks up heat from the exhaust air coil and gives up heat to the supply air coil before returning again. Thus heat from the exhaust air stream is transferred through the pipework coil to the circulating fluid, and then from the fluid through the pipework coil to the supply air stream.
The use of this system is generally limited to situations where the air streams are separated and no other type of device can be utilised since the heat recovery efficiency is lower than other forms of air-to-air heat recovery. Gross efficiencies are usually in the range of 40 to 50%, but more significantly seasonal efficiencies of this system can be very low, due to the extra electrical energy used by the pumped fluid circuit.
The fluid circuit containing the circulating pump also contains an expansion vessel, to accommodate changes in fluid pressure. In addition, there is a fill device to ensure the system remains charged. There are also controls to bypass and shut down the system when not required, and other safety devices. Pipework runs should be as short as possible, and should be sized for low velocities to minimize frictional losses, hence reducing pump energy consumption. It is possible to recover some of this energy in the form of heat given off by the motor if a glandless pump is used, where a water jacket surrounds the motor stator, thus picking up some of its heat.
The pumped fluid will have to be protected from freezing, and is normally treated with a glycol based anti-freeze. This also reduces the specific heat capacity of the fluid and increases the viscosity, increasing pump power consumption, further reducing the seasonal efficiency of the device. For example, a 20% glycol mixture will provide protection down to −10 °C (14 °F), but will increase system resistance by 15%.
For the finned tube coil design, there is a performance maximum corresponding to an eight- or ten-row coil, above this the fan and pump motor energy consumption increases substantially and seasonal efficiency starts to decrease. The main cause of increased energy consumption lies with the fan, for the same face velocity , fewer coil rows will decrease air pressure drop and increase water pressure drop. The total energy consumption will usually be less than that for a greater number of coil rows with higher air pressure drops and lower water pressure drops.
Normally the heat transfer between airstreams provided by the device is termed as ' sensible ', which is the exchange of energy, or enthalpy , resulting in a change in temperature of the medium (air in this case), but with no change in moisture content. | https://en.wikipedia.org/wiki/Run-around_coil |
Run-length encoding ( RLE ) is a form of lossless data compression in which runs of data (consecutive occurrences of the same data value) are stored as a single occurrence of that data value and a count of its consecutive occurrences, rather than as the original run. As an imaginary example of the concept, when encoding an image built up from colored dots, the sequence "green green green green green green green green green" is shortened to "green x 9". This is most efficient on data that contains many such runs, for example, simple graphic images such as icons, line drawings, games, and animations. For files that do not have many runs, encoding them with RLE could increase the file size.
RLE may also refer in particular to an early graphics file format supported by CompuServe for compressing black and white images, that was widely supplanted by their later Graphics Interchange Format (GIF).
RLE also refers to a little-used image format in Windows 3.x that is saved with the file extension rle ; it is a run-length encoded bitmap, and was used as the format for the Windows 3.x startup screen.
Run-length encoding (RLE) schemes were employed in the transmission of analog television signals as far back as 1967. [ 1 ] In 1983, run-length encoding was patented by Hitachi . [ 2 ] [ 3 ] [ 4 ] RLE is particularly well suited to palette -based bitmap images (which use relatively few colours) such as computer icons , and was a popular image compression method on early online services such as CompuServe before the advent of more sophisticated formats such as GIF . [ 5 ] It does not work well on continuous-tone images (which use very many colours) such as photographs, although JPEG uses it on the coefficients that remain after transforming and quantizing image blocks.
Common formats for run-length encoded data include Truevision TGA , PackBits (by Apple, used in MacPaint ), PCX and ILBM . The International Telecommunication Union also describes a standard to encode run-length colour for fax machines, known as T.45. [ 6 ] That fax colour coding standard, which along with other techniques is incorporated into Modified Huffman coding , [ citation needed ] is relatively efficient because most faxed documents are primarily white space, with occasional interruptions of black.
RLE has a space complexity of O ( n ) {\displaystyle O(n)} , where n is the size of the input data.
Run-length encoding compresses data by reducing the physical size of a repeating string of characters. This process involves converting the input data into a compressed format by identifying and counting consecutive occurrences of each character. The steps are as follows:
[ 7 ]
The decoding process involves reconstructing the original data from the encoded format by repeating characters according to their counts. The steps are as follows:
[ 7 ]
Consider a screen containing plain black text on a solid white background. There will be many long runs of white pixels in the blank space, and many short runs of black pixels within the text. A hypothetical scan line , with B representing a black pixel and W representing white, might read as follows:
With a run-length encoding (RLE) data compression algorithm applied to the above hypothetical scan line, it can be rendered as follows:
This can be interpreted as a sequence of twelve Ws, one B, twelve Ws, three Bs, etc., and represents the original 67 characters in only 18. While the actual format used for the storage of images is generally binary rather than ASCII characters like this, the principle remains the same. Even binary data files can be compressed with this method; file format specifications often dictate repeated bytes in files as padding space. However, newer compression methods such as DEFLATE often use LZ77 -based algorithms, a generalization of run-length encoding that can take advantage of runs of strings of characters (such as BWWBWWBWWBWW ).
Run-length encoding can be expressed in multiple ways to accommodate data properties as well as additional compression algorithms. For instance, one popular method encodes run lengths for runs of two or more characters only, using an "escape" symbol to identify runs, or using the character itself as the escape, so that any time a character appears twice it denotes a run. On the previous example, this would give the following:
This would be interpreted as a run of twelve Ws, a B, a run of twelve Ws, a run of three Bs, etc. In data where runs are less frequent, this can significantly improve the compression rate.
One other matter is the application of additional compression algorithms. Even with the runs extracted, the frequencies of different characters may be large, allowing for further compression; however, if the run lengths are written in the file in the locations where the runs occurred, the presence of these numbers interrupts the normal flow and makes it harder to compress. To overcome this, some run-length encoders separate the data and escape symbols from the run lengths, so that the two can be handled independently. For the example data, this would result in two outputs, the string " WWBWWBBWWBWW " and the numbers ( 12,12,3,24,14 ). | https://en.wikipedia.org/wiki/Run-length_encoding |
A run-off transcription assay is an assay in molecular biology which is conducted in vitro to identify the position of the transcription start site (1 base pair upstream) of a specific promoter along with its accuracy and rate of in vitro transcription . [ 1 ] [ 2 ] [ 3 ]
Run-off transcription can be used to quantitatively measure the effect of changing promoter regions on in vitro transcription levels, [ 1 ] [ 2 ] [ 4 ] Because of its in vitro nature, however, this assay cannot accurately predict cell-specific gene transcription rates, unlike in vivo assays such as nuclear run-on. [ 1 ] [ 2 ]
To perform a run-off transcription assay, a gene of interest, including the promoter , is cloned into a plasmid . [ 4 ] The plasmid is digested at a known restriction enzyme cut site downstream from the transcription start site such that the expected mRNA run-off product would be easily separated by gel electrophoresis . [ 1 ] [ 2 ] [ 4 ]
DNA needs to be highly purified prior to running this assay. [ 1 ] [ 2 ] To initiate transcription, radiolabeled UTP , the other nucleotides , and RNA polymerase are added to the linearized DNA. [ 1 ] [ 2 ] Transcription continues until the RNA polymerase reaches the end of the DNA where it simply “runs off” the DNA template, resulting in an mRNA fragment of a defined length. [ 1 ] [ 2 ] This fragment can then be separated by gel electrophoresis, alongside size standards, and autoradiographed. [ 1 ] [ 2 ] [ 4 ] The corresponding size of the band will represent the size of the mRNA from the restriction enzyme cut site to the transcription start site (+1). [ 4 ] The intensity of the band will indicate the amount of mRNA produced. [ 4 ]
Additionally, it can be used to detect whether or not transcription is carried out under certain conditions (i.e. in the presence of different chemicals). [ 5 ] | https://en.wikipedia.org/wiki/Run-off_transcription |
In hydrology , run-on refers to surface runoff from an external area that flows on to an area of interest. A portion of run-on can infiltrate once it reaches the area of interest. Run-on is common in arid and semi-arid areas with patchy vegetation cover and short but intense thunderstorms . In these environments, surface runoff is usually generated by a failure of rainfall to infiltrate into the ground quickly enough (this runoff is termed infiltration excess overland flow). This is more likely to occur on bare soil , with low infiltration capacity . As runoff flows downslope, it may run-on to ground with higher infiltration capacity (such as beneath vegetation) and then infiltrate.
Run-on is an important process in the hydrological and ecohydrological behaviour of semi-arid ecosystems. Tiger bush is an example of a vegetation community that develops a patterned structure in response to, in part, the generation of runoff and run-on.
This ecology -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Run-on |
Run-out or runout is an inaccuracy of rotating mechanical systems, specifically that the tool or shaft does not rotate exactly in line with the main axis . For example; when drilling , run-out will result in a larger hole than the drill's nominal diameter due to the drill
being rotated eccentrically (off axis instead of in line). In the case of bearings , run-out will cause vibration of the machine and increased loads on the bearings. [ 1 ]
Run-out is dynamic and cannot be compensated. If a rotating component, such as a drill chuck, does not hold the drill centrally, then as it rotates the rotating drill will turn about a secondary axis.
Absolute alignment is impossible; a degree of error will always be present.
Run-out has two main forms: [ 2 ]
In addition, irregular run-out is the result of worn or rough bearings which can manifest itself as either axial or radial run-out.
Run-out will be present in any rotating system and, depending on the system, the different forms may either combine increasing total runout, or cancel reducing total runout. At any point along a tool or shaft, it is not possible to determine whether runout is axial or radial; only by measuring along the axis can they be differentiated.
Radial run-out is the result of a rotating component running off centre, such as a ball bearing with an offset centre. This means that the rotating tool or shaft, instead of being centrally aligned, will rotate about a secondary axis. In general, cutting tools are more tolerant of radial run-out since the edges are parallel to the line of cutting tending to keep the tool tip aligned. However, a rotating shaft may be less tolerant of radial run-out since the centre of gravity is displaced by the amount of run-out.
Axial run-out is the result of a rotating component not being parallel with the axis, such as a drill chuck not holding the drill exactly in line with the axis. In general, cutting tools are less tolerant of axial run-out since the tool tip tends to dig in and further increase run-out. However, a shaft may be more tolerant of axial run-out since the centre of gravity is displaced less.
Typically run-out is measured using a dial indicator pressed against the rotating component while it is turned. Full indicator movement (previously called total indicator reading or total indicated run-out, TIR) is a term for the measured run-out of any rotating system, including all forms of run-out, at the measured point. [ 3 ] | https://en.wikipedia.org/wiki/Run-out |
The term runaway electrons (RE) is used to denote electrons that undergo free fall acceleration into the realm of relativistic particles . REs may be classified as thermal (lower energy) or relativistic. The study of runaway electrons is thought to be fundamental to our understanding of High-Energy Atmospheric Physics. [ 1 ] They are also seen in tokamak fusion devices, where they can damage the reactors.
Runaway electrons are the core element of the runaway breakdown based theory of lightning propagation. Since C.T.R. Wilson 's work in 1925, [ 2 ] research has been conducted to study the possibility of runaway electrons, cosmic ray based or otherwise, initiating the processes required to generate lightning. [ 3 ]
Electron runaway based lightning may be occurring on the four giant planets in addition to Earth. Simulated studies predict runaway breakdown processes are likely to occur on these gaseous planets far more easily on earth, as the threshold for runaway breakdown to begin is far smaller. [ 4 ]
The runaway electron phenomenon has been observed in high energy plasmas . They can pose a threat to machines and experiments in which these plasmas exist, including ITER . Several studies exist examining the properties of runaway electrons in these environments ( tokamak ), searching to better suppress the detrimental effects of these unwanted runaway electrons. [ 5 ] Recent measurements reveal higher-than-expected impurity ion diffusion in runaway electron plateaus, possibly due to turbulence. The choice between low and high atomic number (Z) gas injections for disruption mitigation techniques requires a better understanding of the impurity ion transport, as these ions may not completely mix at impact, affecting the prevention of runaway electron wall damage in large tokamak concepts, like ITER. [ 6 ]
Acceleration of electrons to relativistic velocities occurs when the accelerating force of electric fields is stronger than the braking force from collisions with other particles in the plasma. The friction force electrons feels increases monotonically with momentum until the thermal momentum p t h = 2 m e T e {\displaystyle p_{th}={\sqrt {2m_{e}T_{e}}}} is reached, after which it decreases to a very small but finite value as p → ∞ {\displaystyle p\rightarrow \infty } . Therefore with a sufficiently strong electric field, the accelerating force can be larger than the maximum friction force, leading to the indefinite acceleration of electrons to relativistic velocities.
An electron with velocity v ≫ v t h {\displaystyle v\gg v_{th}} will runaway if
e E ∥ > e 4 n e ln Λ 4 π ε 0 2 m e v 2 {\displaystyle eE_{\parallel }>{\frac {e^{4}n_{e}\ln {\Lambda }}{4\pi \varepsilon _{0}^{2}m_{e}v^{2}}}} ,
where m e {\displaystyle m_{e}} and n e {\displaystyle n_{e}} are the electron mass and density respectively, e {\displaystyle e} the elementary charge and ln Λ {\displaystyle \ln {\Lambda }} the [[Coulomb collision#Coulomb logarithm:~:text=2-,Coulomb logarithm,-[edit]|Coulomb logarithm]]. Since the electron velocity is limited by the speed of light c {\displaystyle c} , the critical value of the electric field, below which no electrons will runaway, as derived by Connor and Hastie [ 7 ] is
E c = e 3 n e ln Λ 4 π ε 0 2 m e c 2 {\displaystyle E_{c}={\frac {e^{3}n_{e}\ln {\Lambda }}{4\pi \varepsilon _{0}^{2}m_{e}c^{2}}}} .
There are two different types of runaway generation mechanisms: primary generation or seed generation that does not rely on the existence of runaway electrons, and secondary generation or avalanche multiplication which amplifies the existing runaway population.
An example of primary generation is the Dreicer mechanism , [ 8 ] [ 9 ] where collisional diffusion process strive to maintain the electron distribution in thermal equilibrium , therefore filling any "gaps" left by runaway electrons.
The vast majority of runaway electrons are however generated by secondary mechanisms. Knock-on collisions can multiply the population of seed runaway electrons generated by primary mechanisms. [ 10 ] Furthermore, since the energies of runaway electrons is far higher than the ionization energy of ions in the plasma, bound electrons may also contribute to the avalanche process.
This highly complex phenomenon has proved difficult to model with traditional systems, but has been modelled in part with the world's most powerful supercomputer. [ 11 ] In addition, aspects of electron runaway have been simulated using the popular particle physics modelling module Geant4 . [ 12 ] | https://en.wikipedia.org/wiki/Runaway_electrons |
A runaway train is a type of railroad incident in which unattended rolling stock is accidentally allowed to roll onto the main line, a moving train loses enough braking power to be unable to stop in safety, or a train operates at unsafe speeds due to loss of operator control. If the uncontrolled rolling stock derails or hits another train, it will result in a train wreck .
A deadman's control , if the brakes are working, can prevent unattended rolling stock from moving.
A railway air brake can fail if valves on the pipe between each wagon are accidentally closed; the 1953 Pennsylvania Railroad train wreck and the 1988 Gare de Lyon train accident were results of a valve accidentally closed by the crew, reducing braking power.
A parked train or cut off cars may also run away if not properly tied down with a sufficient number of hand brakes .
Accidents and incidents involving defective or improperly-set railway brakes include: | https://en.wikipedia.org/wiki/Runaway_train |
The Russian Internet ( Russian : русский Интернет ) or Runet (Russian: Рунет ), is the part of the Internet that uses the Russian language , including the Russian-language community on the Internet and websites. Geographically, it reaches all continents, including Antarctica (due to Russian scientists living at Bellingshausen Station [ 1 ] ), but mostly it is based in Russia .
The term Runet is a portmanteau of ru (code for both the Russian language and Russia 's top-level domain ) and internet. The term was coined in 1997 by the Azerbaijani [ 2 ] blogger Raffi Aslanbekov ( Russian : Раффи Асланбеков [ 3 ] ), known as "Great Uncle" in Russia, on his Russian-language column Great Uncle's Thoughts . [ 4 ] [ 5 ] The term was popularized by early Internet users and was included in several dictionaries, including the spelling dictionary of the Russian Academy of Sciences , edited by V. V. Lopatin, as soon as in 2001. A similar, "local to Runet" sub-culture of ChuvashTet later emerged among with alike entities of Uznet ( Uzbekistan ), Kaznet ( Kazakhstan ) and others.
For ordinary users, the term Runet means that the content of websites is available for Russian users without foreign language skills, or that online shops have an office in Russia (for example, Russian search engines, e-mail services, anti-viruses, dictionaries, Russian-language websites occupying niches similar to those of Facebook , Amazon , YouTube , eBay , PayPal , Foursquare , etc. for usage in all post-Soviet states ). Being on the Runet gives a company some advantages, as many local IT companies are more successful than foreign services on the Russian market. The term can describe the situation of the 1990s to the early 2000s; foreign companies didn't want to operate in the Russian market and localize their products, so Russia-based start-ups were more attractive to Russian speaking users. Nowadays, some Russian users are not interested in usage of such services as Facebook or Google Maps because local services have more Russian-specific features and local community ( VK.com , Yandex , etc.), though many international websites have very high quality Russian localization and Google search has had full support of Russian morphology. This is also more or less applicable to most post-Soviet states, who use the Runet and are forming a common lingua franca community like English on the Internet .
Many officials of the Russian government actively use this term as a synonym for Internet in the territory of Russia , i.e. for Internet infrastructure, which is subject to Russian law (including Russian censorship laws , copyright, corporate, advertisement laws, etc.), but the Russian online community doesn't support this use of the term as millions of users use the Russian language on the Internet while living outside Russia; Russian is spoken in large parts of eastern Europe that do not fall under Russian territory. Some Russian officials automatically believe that the Russian Wikipedia is based in Russia as a business entity and try to control the content of the website or establish a Russia-based clone of Wikipedia . [ 6 ] [ 7 ] [ 8 ]
According to reports conducted by Yandex , Russian is the primary language of 91% of Russian websites (in Yandex's list). In the autumn of 2009, Runet contained about 15 million sites (estimated to be about 6.5% of the entire Internet). [ 9 ]
Domains with a high proportion of the Russian language include .su , .ru , .рф , .ua , .by , .kz .
Russian is used on 89.8% of .ru sites and on 88.7% of the former Soviet Union domain, .su. Russian is the most used language of websites of several countries that were part of the former Soviet Union: 79.0% in Ukraine, 86.9% in Belarus, 84.0% in Kazakhstan, 79.6% in Uzbekistan, 75.9% in Kyrgyzstan , and 81.8% in Tajikistan . [ 10 ]
As of 2013, the 59.7 million Russian-speaking Internet users, represented 3% of global Internet users. In April 2012, Russia was ranked 9th in the world [ 1 ] for number of users and 4th (with 4.8%) for number of Russian-language content. [ 11 ]
In September 2011, Russia surpassed Germany as the biggest Internet market in Europe, with 50.8 million users. [ 12 ]
In March 2013, it was announced that Russian is the second most used language on the web. [ 10 ]
Historically the term Runet has been described in several ways.
Harvard University 's Berkman Center conducts regular researches of the Russian-language Web, identified by Cyrillic encoding , [ 21 ] and, in particular, has papers named "Mapping RuNet Politics and Mobilization" [ 22 ] and "RuNet Echo". [ 23 ] The prominent Public Opinion Foundation (FOM) regular Internet measurements are titled Runet.fom.ru. [ 24 ] There are Russian internet-reviewing newspapers called TheRunet, Runetologia and others. | https://en.wikipedia.org/wiki/Runet |
The runner's high is a transient state of euphoria coupled with lessened feelings of anxiety and a higher pain threshold, which can come either from continuous moderate physical exertion over time or from short bursts of high-intensity exercise. The exact prevalence is unknown, but it seems to be a relatively rare phenomenon that not every athlete experiences. [ 1 ] The name comes from distance running , and it is alternatively called " rower's high " in rowing . [ 2 ] [ 3 ] [ 4 ] [ 5 ]
Current medical reviews indicate that several endogenous euphoriants are responsible for producing exercise-related pleasurable feelings, specifically phenethylamine (an endogenous psychostimulant ), β-endorphin (an endogenous opioid ), and anandamide (an endogenous cannabinoid ). [ 6 ] [ 7 ] [ 8 ] [ 9 ] [ 10 ] However, more recent studies suggest that endorphins have a limited role in the feelings of euphoria specifically related to the runner's high due to their inability to cross the blood-brain barrier , placing more importance in the endocannabinoids instead, which can cross this barrier. [ 1 ] [ 4 ] [ 11 ] [ 12 ]
The release of endocannabinoids is greater during longer and more extreme periods of physical exertion, which is why the Runner’s High is more associated with long distance running than sprinting. [ 13 ] Not all runners experience this state, and it is inconsistent despite factors of weight, sex, age. Although, on average more regular runners experience more intense concentration and happiness associated with having a Runner’s high. [ 14 ] New runners even report a lack of experiencing any feeling a Runner’s High, and more of a painful experience rather than immediate experience of Runner’s High. [ 15 ]
There are many different accounts of how the euphoric experience of a Runner’s High feels to an individual. Many runners emphasize a feeling of lessened pain and antinociceptive responses during extreme exertion. [ 13 ]
A runner’s experience of Runner’s High is often characterized by the feeling of a lack of boundaries and the absence of feeling of time, space and body. This feeling allows runners to let go of their surrounding and immediate experience, and disassociate with the physical world to take a back seat. This feeling often leads to a sense of pleasure which makes up the Runner’s High. [ 16 ]
Another common experience which Runner’s describe of the Runner’s High is a greater appreciation and association with the world around them as bodily functions of running become a part of the subconscious. Heightened awareness specifically of natural surroundings is relaxes the mind and leads to runners to experience the high of connecting to the world around them. [ 15 ]
Runner’s High is also prevalent in those who run directly after a long term injury, as the jump from a deep sense of bodily function and pain to a flow state could cause increased feelings of euphoria. [ 15 ]
Many top athletes comment on their experience of Runner’s High, and they mainly attribute their Runner’s high to knocking down their best ever personal times.
Usain Bolt, Jamaican sprinter and world record holder in the 100 meter dash, spoke on his experience with runner’s high. Bolt attributed his euphoric experience to his competitive nature and experience of achieving a personal best, as well as the hard work put into achieving his goals. [ 17 ]
Kate Carter, Runner’s World commissioning editor and sub three hour marathon runner wrote of how her Runner’s High experience helped to get her hooked on running after starting at a later age in life. Carter said her peak ecstatic experience from running was in knocking 20 seconds off of her marathon personal best. [ 18 ] | https://en.wikipedia.org/wiki/Runner's_high |
A running total or rolling total is the summation of a sequence of numbers which is updated each time a new number is added to the sequence, by adding the value of the new number to the previous running total. Another term for it is partial sum .
The purposes of a running total are twofold. First, it allows the total to be stated at any point in time without having to sum the entire sequence each time. Second, it can save having to record the sequence itself, if the particular numbers are not individually important.
Consider the sequence (5, 8, 3, 2). What is the total of this sequence?
Answer : 5 + 8 + 3 + 2 = 18. This is arrived at by simple summation of the sequence.
Now we insert the number 6 at the end of the sequence to get (5, 8, 3, 2, 6). What is the total of that sequence?
Answer : 5 + 8 + 3 + 2 + 6 = 24. This is arrived at by simple summation of the sequence. But if we regarded 18 as the running total, we need only add 6 to 18 to get 24. So, 18 was, and 24 now is, the running total. In fact, we would not even need to know the sequence at all, but simply add 6 to 18 to get the new running total; as each new number is added, we get a new running total.
The same method will also work with subtraction, but in that case it is not strictly speaking a total (which implies summation) but a running difference; not to be confused with a delta . This is used, for example, when scoring the game of darts . Similarly one can multiply instead of add to get the running product.
While this concept is very simple, it is extremely common in everyday use. For example, most cash registers display a running total of the purchases so far rung in. By the end of the transaction this will, of course, be the total of all the goods. Similarly, the machine may keep a running total of all transactions made, so that at any point in time the total can be checked against the amount in the till, even though the machine has no memory of past transactions.
Typically many games of all kinds use running totals for scoring; the actual values of past events in the sequence are not important, only the current score, that is to say, the running total.
The central processing unit of computers for many years had a component called the accumulator . [ 1 ] : 7 This accumulator, essentially, kept a running total; that is, it "accumulated" the results of individual calculations. This term is largely obsolete with more modern computers. A betting accumulator is the running product of the outcomes of several bets in sequence. | https://en.wikipedia.org/wiki/Running_total |
Runoff is the flow of water across the earth, and is a major component in the hydrological cycle . Runoff that flows over land before reaching a watercourse is referred to as surface runoff or overland flow . Once in a watercourse , runoff is referred to as streamflow , channel runoff , or river runoff . Urban runoff is surface runoff created by urbanization .
The water cycle (or hydrologic cycle or hydrological cycle) is a biogeochemical cycle that involves the continuous movement of water on, above and below the surface of the Earth across different reservoirs. The mass of water on Earth remains fairly constant over time. [ 2 ] However, the partitioning of the water into the major reservoirs of ice , fresh water , salt water and atmospheric water is variable and depends on climatic variables . The water moves from one reservoir to another, such as from river to ocean , or from the ocean to the atmosphere due to a variety of physical and chemical processes. The processes that drive these movements, or fluxes , are evaporation , transpiration , condensation , precipitation , sublimation , infiltration , surface runoff , and subsurface flow. In doing so, the water goes through different phases: liquid, solid ( ice ) and vapor . The ocean plays a key role in the water cycle as it is the source of 86% of global evaporation. [ 3 ]
The water cycle is driven by energy exchanges in the form of heat transfers between different phases. The energy released or absorbed during a phase change can result in temperature changes. [ 4 ] Heat is absorbed as water transitions from the liquid to the vapor phase through evaporation. This heat is also known as the latent heat of vaporization. [ 5 ] Conversely, when water condenses or melts from solid ice it releases energy and heat. On a global scale, water plays a critical role in transferring heat from the tropics to the poles via ocean circulation. [ 6 ]
The evaporative phase of the cycle also acts as a purification process by separating water molecules from salts and other particles that are present in its liquid phase. [ 7 ] The condensation phase in the atmosphere replenishes the land with freshwater. The flow of liquid water transports minerals across the globe. It also reshapes the geological features of the Earth, through processes of weathering, erosion , and deposition. The water cycle is also essential for the maintenance of most life and ecosystems on the planet.
Surface runoff (also known as overland flow or terrestrial runoff) is the unconfined flow of water over the ground surface, in contrast to channel runoff (or stream flow ). It occurs when excess rainwater , stormwater , meltwater , or other sources, can no longer sufficiently rapidly infiltrate in the soil . This can occur when the soil is saturated by water to its full capacity, and the rain arrives more quickly than the soil can absorb it. Surface runoff often occurs because impervious areas (such as roofs and pavement ) do not allow water to soak into the ground. Furthermore, runoff can occur either through natural or human-made processes. [ 10 ]
Surface runoff is a major component of the water cycle . It is the primary agent of soil erosion by water . [ 11 ] [ 12 ] The land area producing runoff that drains to a common point is called a drainage basin .
Runoff that occurs on the ground surface before reaching a channel can be a nonpoint source of pollution , as it can carry human-made contaminants or natural forms of pollution (such as rotting leaves). Human-made contaminants in runoff include petroleum , pesticides , fertilizers and others. [ 13 ] Much agricultural pollution is exacerbated by surface runoff, leading to a number of down stream impacts, including nutrient pollution that causes eutrophication .
Urban runoff is surface runoff of rainwater, landscape irrigation, and car washing [ 14 ] created by urbanization . Impervious surfaces ( roads , parking lots and sidewalks ) are constructed during land development . During rain , storms, and other precipitation events, these surfaces (built from materials such as asphalt and concrete ), along with rooftops , carry polluted stormwater to storm drains , instead of allowing the water to percolate through soil . [ 15 ]
This causes lowering of the water table (because groundwater recharge is lessened) and flooding since the amount of water that remains on the surface is greater. [ 16 ] [ 17 ] Most municipal storm sewer systems discharge untreated stormwater to streams , rivers , and bays . This excess water can also make its way into people's properties through basement backups and seepage through building wall and floors.
A runoff models or rainfall-runoff model describes how rainfall is converted into runoff in a drainage basin (catchment area or watershed). More precisely, it produces a surface runoff hydrograph in response to a rainfall event, represented by and input as a hyetograph .
Rainfall-runoff models need to be calibrated before they can be used.
A well known runoff model is the linear reservoir , but in practice it has limited applicability.
This hydrology article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Runoff_(hydrology) |
The runoff curve number (also called a curve number or simply CN ) is an empirical parameter used in hydrology for predicting direct runoff or infiltration from rainfall excess. [ 1 ] The curve number method was developed by the USDA Natural Resources Conservation Service , which was formerly called the Soil Conservation Service or SCS — the number is still popularly known as a "SCS runoff curve number" in the literature. The runoff curve number was developed from an empirical analysis of runoff from small catchments and hillslope plots monitored by the USDA. It is widely used and is an efficient method for determining the approximate amount of direct runoff from a rainfall event in a particular area.
The runoff curve number is based on the area's hydrologic soil group, land use , treatment and hydrologic condition. References, such as from USDA [ 1 ] indicate the runoff curve numbers for characteristic land cover descriptions and a hydrologic soil group.
The runoff equation is:
where
The runoff curve number, C N {\displaystyle CN} , is then related
C N {\displaystyle CN} has a range from 30 to 100; lower numbers indicate low runoff potential while larger numbers are for increasing runoff potential. The lower the curve number, the more permeable the soil is. As can be seen in the curve number equation, runoff cannot begin until the initial abstraction has been met. It is important to note that the curve number methodology is an event-based calculation, and should not be used for a single annual rainfall value, as this will incorrectly miss the effects of antecedent moisture and the necessity of an initial abstraction threshold.
The NRCS curve number is related to soil type, soil infiltration capability, land use, and the depth of the seasonal high water table. To account for different soils' ability to infiltrate, NRCS has divided soils into four hydrologic soil groups (HSGs). They are defined as follows. [ 1 ]
Selection of a hydrologic soil group should be done based on measured infiltration rates, soil survey (such as the NRCS Web Soil Survey ), or judgement from a qualified soil science or geotechnical professional. The table below presents curve numbers for antecedent soil moisture condition II (average moisture condition). To alter the curve number based on moisture condition or other parameters, see Adjustments .
Runoff is affected by the soil moisture before a precipitation event, the antecedent moisture condition (AMC). A curve number, as calculated above, may also be termed AMC II or C N I I {\displaystyle CN_{II}} , or average soil moisture. The other moisture conditions are dry, AMC I or C N I {\displaystyle CN_{I}} , and moist, AMC III or C N I I I {\displaystyle CN_{III}} . The curve number can be adjusted by factors to C N I I {\displaystyle CN_{II}} , where C N I {\displaystyle CN_{I}} factors are less than 1 (reduce C N {\displaystyle CN} and potential runoff), while C N I I I {\displaystyle CN_{III}} factor are greater than 1 (increase C N {\displaystyle CN} and potential runoff). The AMC factors can be looked up in the reference table below. Find the CN value for AMC II and multiply it by the adjustment factor based on the actual AMC to determine the adjusted curve number.
The relationship I a = 0.2 S {\displaystyle I_{a}=0.2S} was derived from the study of many small, experimental watersheds . Since the history and documentation of this relationship are relatively obscure, more recent analysis used model fitting methods to determine the ratio of I a {\displaystyle I_{a}} to S {\displaystyle S} with hundreds of rainfall-runoff data from numerous U.S. watersheds. In the model fitting done by Hawkins et al. (2002) [ 2 ] found that the ratio of I a {\displaystyle I_{a}} to S {\displaystyle S} varies from storm to storm and watershed to watershed and that the assumption of I a / S = 0.20 {\displaystyle I_{a}/S=0.20} is usually high. More than 90 percent of I a / S {\displaystyle I_{a}/S} ratios were less than 0.2. Based on this study, use of I a / S {\displaystyle I_{a}/S} ratios of 0.05 rather than the commonly used value of 0.20 would seem more appropriate. Thus, the CN runoff equation becomes:
In this equation, note that the values of S 0.05 {\displaystyle S_{0.05}} are not the same as the one used in estimating direct runoff with an I a / S {\displaystyle I_{a}/S} ratio of 0.20, because 5 percent of the storage is assumed to be the initial abstraction, not 20 percent. The relationship between S 0.05 {\displaystyle S_{0.05}} and S 0.20 {\displaystyle S_{0.20}} was obtained from model fitting results, giving the relationship:
The user, then, must do the following to use the adjusted 0.05 initial abstraction ratio: | https://en.wikipedia.org/wiki/Runoff_curve_number |
A runoff footprint is the total surface runoff that a site produces over the course of a year. According to the United States Environmental Protection Agency (EPA) stormwater is "rainwater and melted snow that runs off streets, lawns, and other sites". [ 1 ] Urbanized areas with high concentrations of impervious surfaces like buildings, roads, and driveways produce large volumes of runoff which can lead to flooding, sewer overflows, and poor water quality . Since soil in urban areas can be compacted and have a low infiltration rate , the surface runoff estimated in a runoff footprint is not just from impervious surfaces, but also pervious areas including yards. The total runoff is a measure of the site’s contribution to stormwater issues in an area, especially in urban areas with sewer overflows. Completing a runoff footprint for a site allows a property owner to understand what areas on his or her site are producing the most runoff and what scenarios of stormwater green solutions like rain barrels and rain gardens are most effective in mitigating this runoff and its costs to the community.
The runoff footprint is the stormwater equivalent to the carbon/energy footprint. When homeowners or business owners complete an energy audit or carbon footprint , they understand how they are consuming energy and learn how this consumption can be reduced through energy efficiency measures. Correspondingly, the runoff footprint allows someone to calculate their baseline annual runoff and assess what the impact of ideal stormwater green solutions would be for their site. Since the passage of the Clean Water Act in 1972, the EPA has monitored and regulated stormwater issues in urban areas. Municipalities across the United States are now required to upgrade sanitary and stormwater systems to meet EPA mandates. The total cost for these upgrades across the United States exceeds $3000 billion. [ 2 ] [ 3 ] The stormwater runoff from every property in an area can contribute to the overall stormwater issues including overflows and water pollution. Stormwater runoff carries nonpoint source pollution which is a leading cause of water quality issues. [ 4 ]
By completing a runoff footprint, homeowners and business owners can consider how stormwater green solutions can reduce runoff on-site. Stormwater green solutions (also called green infrastructure ) use "vegetation, soils, and natural processes to manage water and create healthier urban environments. At the scale of a city or county, green infrastructure refers to the patchwork of natural areas that provides habitat, flood protection, cleaner air, and cleaner water. At the scale of a neighborhood or site, green infrastructure refers to stormwater management systems that mimic nature by soaking up and storing water". [ 5 ] Stormwater green solutions include bioswales (directional rain gardens), cisterns, green roofs, permeable pavement, rain barrels, and rain gardens. According to the EPA, onsite stormwater green solutions or low-impact developments (LIDs) can significantly reduce runoff and costly stormwater/sewer infrastructure upgrades. [ 6 ]
Stormwater green solutions can also reduce energy consumption. Treating and pumping water is an energy-intensive activity. According to the River Network, the U.S. consumes at least 521 million MWh a year for water-related purposes which is the equivalent to 13% of the nation’s electricity consumption [ 7 ] Potable water must be treated and then pumped to the consumer. Wastewater is treated before being discharged. In areas with combined sewer systems or old separate sewer systems with high inflow and infiltration , stormwater is also treated at the wastewater treatment facilities. By capturing stormwater runoff onsite in rain barrels and cisterns, the consumption of potable water for irrigation and its corresponding energy impact can be reduced. The reduction of runoff from all types of stormwater green solutions reduces the stormwater that may end up at the wastewater treatment facility in areas with combined sewer systems or old separate sewers.
There are number of methods available to complete a runoff footprint. The simplest methods involve using a runoff coefficient, which according to the State Water Resources Control Board of California is "a dimensionless coefficient relating the amount of runoff to the amount of precipitation received. It is a larger value for areas with low infiltration and high runoff (pavement, steep gradient), and lower for permeable, well vegetated areas (forest, flat land)." [ 8 ] The runoff coefficients for different surface types on a site can be multiplied with the area for each surface along with the annual precipitation to generate a rough runoff footprint. If the runoff coefficient and areas of proposed stormwater green solutions like rain gardens and bioswales for the site are known, the reduction in overall runoff from these improvements can be estimated.
More accurate runoff footprint tools exist. By using computer modeling and detailed weather data, complex runoff footprints can be made easy. The amounts of pollution in the stormwater runoff can be estimated, and the effects of combinations of stormwater green solutions can be assessed. The James River Association of central Virginia provides an online tool where property owners in the James River watershed can generate a site-specific runoff pollution report. [ 9 ] MyRunoff.org provides an online runoff footprint calculator for property owners across the United States to estimate their baseline runoff and the reduction from different scenarios of rain barrels and rain gardens. [ 10 ] The EPA launched the National Stormwater Calculator in July, 2013, which is a desktop application for Windows allowing users to model the annual impact of a range of stormwater green solutions. [ 11 ] | https://en.wikipedia.org/wiki/Runoff_footprint |
A runoff models or rainfall-runoff model describes how rainfall is converted into runoff in a drainage basin (catchment area or watershed). More precisely, it produces a surface runoff hydrograph in response to a rainfall event, represented by and input as a hyetograph .
Rainfall-runoff models need to be calibrated before they can be used.
A well known runoff model is the linear reservoir , but in practice it has limited applicability.
The runoff model with a non-linear reservoir is more universally applicable, but still it holds only for catchments whose surface area is limited by the condition that the rainfall can be considered more or less uniformly distributed over the area. The maximum size of the watershed then depends on the rainfall characteristics of the region. When the study area is too large, it can be divided into sub-catchments and the various runoff hydrographs may be combined using flood routing techniques.
The hydrology of a linear reservoir (figure 1) is governed by two equations. [ 1 ]
where: Q is the runoff or discharge R is the effective rainfall or rainfall excess or recharge A is the constant reaction factor or response factor with unit [1/T] S is the water storage with unit [L] dS is a differential or small increment of S dT is a differential or small increment of T
Runoff equation A combination of the two previous equations results in a differential equation , whose solution is:
This is the runoff equation or discharge equation , where Q1 and Q2 are the values of Q at time T1 and T2 respectively while T2−T1 is a small time step during which the recharge can be assumed constant.
Computing the total hydrograph Provided the value of A is known, the total hydrograph can be obtained using a successive number of time steps and computing, with the runoff equation , the runoff at the end of each time step from the runoff at the end of the previous time step.
Unit hydrograph The discharge may also be expressed as: Q = − dS/dT . Substituting herein the expression of Q in equation (1) gives the differential equation dS/dT = A·S, of which the solution is: S = exp(− A·t) . Replacing herein S by Q/A according to equation (1), it is obtained that: Q = A exp(− A·t) . This is called the instantaneous unit hydrograph (IUH) because the Q herein equals Q2 of the foregoing runoff equation using R = 0, and taking S as unity which makes Q1 equal to A according to equation (1). The availability of the foregoing runoff equation eliminates the necessity of calculating the total hydrograph by the summation of partial hydrographs using the IUH as is done with the more complicated convolution method. [ 2 ]
Determining the response factor A When the response factor A can be determined from the characteristics of the watershed (catchment area), the reservoir can be used as a deterministic model or analytical model , see hydrological modelling . Otherwise, the factor A can be determined from a data record of rainfall and runoff using the method explained below under non-linear reservoir . With this method the reservoir can be used as a black box model.
Conversions 1 mm/day corresponds to 10 m 3 /day per ha of the watershed 1 L/s per ha corresponds to 8.64 mm/day or 86.4 m 3 /day per ha
Contrary to the linear reservoir, the non linear reservoir has a reaction factor A that is not a constant, [ 3 ] but it is a function of S or Q (figure 2, 3).
Normally A increases with Q and S because the higher the water level is the higher the discharge capacity becomes. The factor is therefore called Aq instead of A. The non-linear reservoir has no usable unit hydrograph .
During periods without rainfall or recharge, i.e. when R = 0, the runoff equation reduces to
or, using a unit time step (T2 − T1 = 1) and solving for Aq:
Hence, the reaction or response factor Aq can be determined from runoff or discharge measurements using unit time steps during dry spells, employing a numerical method .
Figure 3 shows the relation between Aq (Alpha) and Q for a small valley (Rogbom) in Sierra Leone. Figure 4 shows observed and simulated or reconstructed discharge hydrograph of the watercourse at the downstream end of the same valley. [ 4 ] [ 5 ]
The recharge, also called effective rainfall or rainfall excess , can be modeled by a pre-reservoir (figure 6) giving the recharge as overflow . The pre-reservoir knows the following elements:
The recharge during a unit time step (T2−T1=1) can be found from R = Rain − Sd The actual storage at the end of a unit time step is found as Sa2 = Sa1 + Rain − R − Ea, where Sa1 is the actual storage at the start of the time step.
The Curve Number method (CN method) gives another way to calculate the recharge. The initial abstraction herein compares with Sm − Si, where Si is the initial value of Sa.
The Nash model [ 7 ] uses a series (cascade) of linear reservoirs in which each reservoir empties into the next until the runoff is obtained. For calibration , the model requires considerable research.
Figures 3 and 4 were made with the RainOff program, [ 8 ] designed to analyse rainfall and runoff using the non-linear reservoir model with a pre-reservoir. The program also contains an example of the hydrograph of an agricultural subsurface drainage system for which the value of A can be obtained from the system's characteristics. [ 9 ]
Raven is a robust and flexible hydrological modelling framework, designed for application to challenging hydrological problems in academia and practice. This fully object-oriented code provides complete flexibility in spatial discretization, interpolation, process representation, and forcing function generation. Models built with Raven can be as simple as a single watershed lumped model with only a handful of state variables to a full semi-distributed system model with physically-based infiltration, snowmelt, and routing. This flexibility encourages stepwise modelling while enabling investigation into critical research issues regarding discretization, numerical implementation, and ensemble simulation of surface water hydrological models. Raven is open source, covered under the Artistic License 2.0.
The SMART hydrological model [ 10 ] includes agricultural subsurface drainage flow, in addition to soil and groundwater reservoirs, to simulate the flow path contributions to streamflow.
V flo is another software program for modeling runoff. V flo uses radar rainfall and GIS data to generate physics-based, distributed runoff simulation.
The WEAP (Water Evaluation And Planning) software platform models runoff and percolation from climate and land use data, using a choice of linear and non-linear reservoir models.
The RS MINERVE software platform simulates the formation of free surface run-off flow and its propagation in rivers or channels. The software is based on object-oriented programming and allows hydrologic and hydraulic modeling according to a semi-distributed conceptual scheme with different rainfall-runoff model such as HBV, [ 11 ] GR4J, SAC-SMA or SOCONT.
The IHACRES is a catchment-scale rainfall-streamflow modelling methodology. Its purpose is to assist the hydrologist or water resources engineer to characterise the dynamic relationship between basin rainfall and streamflow. [ 12 ] | https://en.wikipedia.org/wiki/Runoff_model_(reservoir) |
Runs of homozygosity (ROH) are contiguous lengths of homozygous genotypes that are present in an individual due to parents transmitting identical haplotypes to their offspring. [ 1 ]
The potential of predicting or estimating individual autozygosity for a subpopulation is the proportion of the autosomal genome above a specified length, termed F roh . [ 2 ]
A research study in UK Biobank , All of Us and Million Veteran Program found that F ROH declines over time. [ 3 ]
This technique can be used to identify the genomic footprint of inbreeding in conservation programs, as organisms that have undergone recent inbreeding will exhibit long runs of homozygosity. For example, the step-wise reintroduction strategy of the Alpine Ibex in the Swiss Alps created several strong population bottlenecks that reduced the genetic diversity of the newly introduced individuals. The effect of inbreeding in the resulting sub-populations could be studied by measuring the runs of homozygosity in different individuals. [ 4 ]
In clinical laboratory testing, the detection of ROH in itself does not indicate a particular genetic disorder but indicates an increased risk of autosomal recessive inherited diseases. [ 5 ] As ROHs smaller than 3 Mb spread throughout the genome are common even in outbred populations, [ 6 ] these segments were usually thought to not be important enough to report. [ 5 ] Large ROH can be indicative of uniparental isodisomy [ 7 ] with follow-up testing to rule out false positives, there is currently no consistent reporting standards among different laboratories. [ 5 ]
ROH can be used to detect the possibility of incest in humans. [ 8 ] [ 5 ] | https://en.wikipedia.org/wiki/Runs_of_homozygosity |
In a group of animals (usually a litter of animals born in multiple births), a runt is a member which is significantly smaller or weaker than the others. [ 1 ] Owing to its small size, a runt in a litter faces disadvantage, including difficulties in competing with its siblings for survival and possible rejection by its mother. Therefore, in the wild, a runt is less likely to survive infancy .
Even among domestic animals , runts often face rejection. They may be placed under the direct care of an experienced animal breeder , although the animal's size and weakness coupled with the lack of natural parental care make this difficult. Some tamed animals are the result of reared runts.
Not all litters have runts. All animals in a litter will naturally vary slightly in size and weight, but the smallest is not considered a "runt" if it is healthy and close in weight to its littermates. It may be perfectly capable of competing with its siblings for nutrition and other resources. A runt is specifically an animal that suffered in utero from deprivation of nutrients by comparison to its siblings, or from a genetic defect, and thus is born underdeveloped or less fit than expected.
Research in a news journal [ which? ] about a runt pup highlights important factors including maternal care, genetic factors, health concerns, and personality development associated with runt pups. Maternal care is crucial as, in some cases, the runt may face difficulties competing with their larger siblings for nutrients. It is important that a runt receive its fair share of milk from their mothers so they can continue growing. Genetic factors play a role in why a puppy is born a runt; it could be because of fertilization process or placental issues. They may face congenital health problems like a heart defect , cleft palate , and any organ defects. Getting a veterinary evaluation is crucial to address potential health problems. Not all runt pups are weak or unhealthy. With proper care and attention, runts can have positive personality traits and be well socialized and happy.
Another animal species where the birth of runts is common is in pigs , especially in large litters where competition for resources is higher. Research has shown that genetic improvements have been made in pig breeding that have resulted in an increase in low birthweight piglets, known as runts. They face challenges in accessing colostrum and milk, which are a competitive environment in large litters. A study in the National Library of Medicine showed the effects of uniform litters of different birth weights on piglets’ survival and performance. When a litter of piglets are similar in size, runts have a better chance of survival since there is less competition between all of them. By understanding and improving litter uniformity, farmers and animal caregivers give the runt of the litter a chance for survival, reducing pre-weaning mortality.
Runts, whether puppies or kittens, need special attention and care, so they have the best survival rate. The Akron Beacon Journal mentioned runts are adopted faster from shelters as their small size and perceived vulnerability makes them appealing to potential adopters. While there are many risks once they are born, once they make it to 6-8 weeks the chance of survival is high, and the runt will most likely grow to full size. While pet runts have a higher likelihood of being wanted, this is not the case with runts of farm animals like pigs. In agricultural settings, when a runt pig is born, a farmer is most likely inclined to cull the animal as they will not be able to reach the proper size for meat production. In the wild, a runt's chance of survival is lower as only the strongest survive. Wild animals do not have the same opportunities for care as domesticated animals.
https://www.whole-dog-journal.com/puppies/what-is-the-runt-of-the-litter/
https://www.beaconjournal.com/story/lifestyle/home-garden/2012/10/06/as-pets-runts-can-be/10712851007/ | https://en.wikipedia.org/wiki/Runt |
Execution in computer and software engineering is the process by which a computer or virtual machine interprets and acts on the instructions of a computer program . Each instruction of a program is a description of a particular action which must be carried out, in order for a specific problem to be solved. Execution involves repeatedly following a " fetch–decode–execute " cycle for each instruction done by the control unit . As the executing machine follows the instructions, specific effects are produced in accordance with the semantics of those instructions.
Programs for a computer may be executed in a batch process without human interaction or a user may type commands in an interactive session of an interpreter . In this case, the "commands" are simply program instructions, whose execution is chained together.
The term run is used almost synonymously. A related meaning of both "to run" and "to execute" refers to the specific action of a user starting (or launching or invoking ) a program, as in "Please run the application."
Prior to execution, a program must first be written. This is generally done in source code , which is then compiled at compile time (and statically linked at link time ) to produce an executable. This executable is then invoked, most often by an operating system, which loads the program into memory ( load time ), possibly performs dynamic linking , and then begins execution by moving control to the entry point of the program; all these steps depend on the Application Binary Interface of the operating system. At this point execution begins and the program enters run time . The program then runs until it ends, either in a normal termination or a crash .
Executable code , an executable file , or an executable program , sometimes simply referred to as an executable or binary , is a list of instructions and data to cause a computer "to perform indicated tasks according to encoded instructions ", [ 1 ] as opposed to a data file that must be interpreted ( parsed ) by a program to be meaningful.
The exact interpretation depends upon the use. "Instructions" is traditionally taken to mean machine code instructions for a physical CPU . [ 2 ] In some contexts, a file containing scripting instructions (such as bytecode ) may also be considered executable.
The context in which execution takes place is crucial. Very few programs execute on a bare machine . Programs usually contain implicit and explicit assumptions about resources available at the time of execution. Most programs execute within multitasking operating system and run-time libraries specific to the source language that provide crucial services not supplied directly by the computer itself. This supportive environment, for instance, usually decouples a program from direct manipulation of the computer peripherals, providing more general, abstract services instead.
In order for programs and interrupt handlers to work without interference and share the same hardware memory and access to the I/O system, in a multitasking operating system running on a digital system with a single CPU/MCU, it is required to have some sort of software and hardware facilities to keep track of an executing process's data (memory page addresses, registers etc.) and to save and recover them back to the state they were in before they were suspended. This is achieved by a context switching. [ 3 ] : 3.3 [ 4 ] The running programs are often assigned a Process Context IDentifiers (PCID).
In Linux-based operating systems, a set of data stored in registers is usually saved into a process descriptor in memory to implement switching of context. [ 3 ] PCIDs are also used.
Runtime , run time , or execution time is the final phase of a computer program ' s life cycle , in which the code is being executed on the computer's central processing unit (CPU) as machine code . In other words, "runtime" is the running phase of a program.
A runtime error is detected after or during the execution (running state) of a program, whereas a compile-time error is detected by the compiler before the program is ever executed. Type checking , register allocation , code generation , and code optimization are typically done at compile time, but may be done at runtime depending on the particular language and compiler. Many other runtime errors exist and are handled differently by different programming languages , such as division by zero errors, domain errors, array subscript out of bounds errors, arithmetic underflow errors, several types of underflow and overflow errors, and many other runtime errors generally considered as software bugs which may or may not be caught and handled by any particular computer language.
When a program is to be executed, a loader first performs the necessary memory setup and links the program with any dynamically linked libraries it needs, and then the execution begins starting from the program's entry point . In some cases, a language or implementation will have these tasks done by the language runtime instead, though this is unusual in mainstream languages on common consumer operating systems.
Some program debugging can only be performed (or is more efficient or accurate when performed) at runtime. Logic errors and array bounds checking are examples. For this reason, some programming bugs are not discovered until the program is tested in a production environment with real data, despite sophisticated compile-time checking and pre-release testing. In this case, the end-user may encounter a "runtime error" message.
Exception handling is one language feature designed to handle runtime errors, providing a structured way to catch completely unexpected situations as well as predictable errors or unusual results without the amount of inline error checking required of languages without it. More recent advancements in runtime engines enable automated exception handling which provides "root-cause" debug information for every exception of interest and is implemented independent of the source code, by attaching a special software product to the runtime engine.
A runtime system , also called runtime environment , primarily implements portions of an execution model . [ clarification needed ] This is not to be confused with the runtime lifecycle phase of a program, during which the runtime system is in operation. When treating the runtime system as distinct from the runtime environment (RTE), the first may be defined as a specific part of the application software (IDE) used for programming , a piece of software that provides the programmer a more convenient environment for running programs during their production ( testing and similar), while the second (RTE) would be the very instance of an execution model being applied to the developed program which is itself then run in the aforementioned runtime system .
Most programming languages have some form of runtime system that provides an environment in which programs run. This environment may address a number of issues including the management of application memory , how the program accesses variables , mechanisms for passing parameters between procedures , interfacing with the operating system , and otherwise. The compiler makes assumptions depending on the specific runtime system to generate correct code. Typically the runtime system will have some responsibility for setting up and managing the stack and heap , and may include features such as garbage collection , threads or other dynamic features built into the language. [ 5 ]
The instruction cycle (also known as the fetch–decode–execute cycle , or simply the fetch-execute cycle ) is the cycle that the central processing unit (CPU) follows from boot-up until the computer has shut down in order to process instructions. It is composed of three main stages: the fetch stage, the decode stage, and the execute stage.
In simpler CPUs, the instruction cycle is executed sequentially, each instruction being processed before the next one is started. In most modern CPUs, the instruction cycles are instead executed concurrently , and often in parallel , through an instruction pipeline : the next instruction starts being processed before the previous instruction has finished, which is possible because the cycle is broken up into separate steps. [ 6 ]
A system that executes a program is called an interpreter of the program. Loosely speaking, an interpreter directly executes a program. This contrasts with a language translator that converts a program from one language to another before it is executed.
A virtual machine ( VM ) is the virtualization / emulation of a computer system . Virtual machines are based on computer architectures and provide functionality of a physical computer. Their implementations may involve specialized hardware, software, or a combination.
Virtual machines differ and are organized by their function, shown here:
Some virtual machine emulators, such as QEMU and video game console emulators , are designed to also emulate (or "virtually imitate") different system architectures thus allowing execution of software applications and operating systems written for another CPU or architecture. OS-level virtualization allows the resources of a computer to be partitioned via the kernel . The terms are not universally interchangeable. | https://en.wikipedia.org/wiki/Runtime_(program_lifecycle_phase) |
Turbo Pascal is a software development system that includes a compiler and an integrated development environment (IDE) for the programming language Pascal running on the operating systems CP/M , CP/M-86 , and MS-DOS . It was originally developed by Anders Hejlsberg at Borland , and was notable for its very fast compiling. Turbo Pascal, and the later but similar Turbo C , made Borland a leader in PC-based development tools.
For versions 6 and 7 (the last two versions), both a lower-priced Turbo Pascal and more expensive Borland Pascal were produced; Borland Pascal was oriented more toward professional software development, with more libraries and standard library source code . The name Borland Pascal is also used more generically for Borland's dialect of the language Pascal, significantly different from Standard Pascal.
Borland has released three old versions of Turbo Pascal free of charge because of their historical interest: the original Turbo Pascal (now known as 1.0), and versions 3.02 and 5.5 for DOS, while Borland's French office released version 7.01 on its FTP. [ 3 ] [ 4 ] [ 5 ]
Philippe Kahn first saw an opportunity for Borland, his newly formed software company, in the field of programming tools. Historically, the vast majority of programmers saw their workflow in terms of the edit/compile/link cycle, with separate tools dedicated to each task. Programmers wrote source code using a text editor ; the source code was then compiled into object code (often requiring multiple passes), and a linker combined object code with runtime libraries to produce an executable program.
In the early IBM PC market (1981–1983) the major programming tool vendors all made compilers that worked in a similar fashion. For example, the Microsoft Pascal system consisted of two compiler passes and a final linking pass (which could take minutes on systems with only floppy disks for secondary storage, even though programs were very much smaller than they are today). This process was less resource-intensive than the later integrated development environment (IDE). Vendors of software development tools aimed their products at professional developers, and the price for these basic tools plus ancillary tools like profilers ran into the hundreds of dollars.
Kahn's idea was to package all these functions in an integrated programming toolkit designed to have much better performance and resource utilization than the usual professional development tools, and charge a low price for a package integrating a custom text editor, compiler, and all functionality needed to produce executable programs. The program was sold by direct mail order for US$ 49.95 , without going through established sales channels (retailers or resellers). [ 6 ]
The Turbo Pascal compiler was based on the Blue Label Pascal compiler originally produced for the NasSys cassette-based operating system of the Nascom microcomputer in 1981 by Anders Hejlsberg . Borland licensed Hejlsberg's "PolyPascal" compiler core ( Poly Data was the name of Hejlsberg's company in Denmark), and added the user interface and editor. Anders Hejlsberg joined the company as an employee and was the architect for all versions of the Turbo Pascal compiler and the first three versions of Borland Delphi . [ 3 ]
The compiler was first released as Compas Pascal for CP/M , and then released on 20 November 1983 [ 2 ] as Turbo Pascal for CP/M (including the Apple II fitted with a Z-80 SoftCard , effectively converting the 6502 -based Apple into a CP/M machine, the Commodore 64 with CP/M cartridge, and the later DEC Rainbow ), CP/M-86, and DOS machines. On its launch in the United States market, Turbo Pascal retailed for US$ 49.99 , a very low price for a compiler at the time. The integrated Pascal compiler was of good quality compared to other Pascal products of the time. [ 7 ]
The Turbo name alluded to the speed of compiling and of the executables produced. The edit/compile/run cycle was fast compared to other Pascal implementations because everything related to building the program was stored in RAM, and because it was a one-pass compiler written in assembly language . Compiling was much faster than compilers for other languages (even Borland's own later compilers for C), [ citation needed ] and other Pascal compilers, and programmer time was also saved since the program could be compiled and run from the IDE. The execution speed of these COM -format programs was a revelation for developers whose only prior experience programming microcomputers was with interpreted BASIC or UCSD Pascal , which compiled to p-code which was then interpreted at runtime.
Unlike some other development tools, Turbo Pascal disks had no copy protection . Turbo Pascal came with the "Book License": "You must treat this software just like a book ... [it] may be used by any number of people ... may be freely moved from one computer location to another, so long as there is no possibility of it being used at one location while it's being used at another." [ 8 ]
Borland sold about 250,000 copies of Turbo Pascal in two years, which Bruce F. Webster of Byte described as "an amazing figure for a computer language". [ 9 ] He reported six months later that the figure had risen to "more than 400,000 copies in a marketplace that had been estimated as having only 30,000 potential buyers". [ 10 ]
Jerry Pournelle wrote in the magazine in February 1984 that Turbo Pascal "comes close to what I think the computer industry is headed for: well documented, standard, plenty of good features, and a reasonable price". He disliked the requirement to buy another license to distribute binaries, but noted that "it turns out not to be a lot more. Borland only wants another $100 " atop the $49.95 base price, and that "my first impression of Turbo is that it's probably worth $149.95 . It looks to do everything MT+ with the Speed Programming Package does, and maybe even do it faster and better". [ 11 ] Pournelle reported in July that Turbo 2.0's overlays "[allow] you to write big programs". According to Kahn, IBM had refused to resell Turbo Pascal unless the price was at least $200 ; Pournelle noted that "Turbo is much better than the Pascal IBM sells", and unlike the latter was compatible with the IBM PCjr . [ 12 ] Three Byte reviewers praised Turbo Pascal in the same issue. One reviewer said that because of dialect differences "Turbo is not really Pascal. But it's very useful". While cautioning that it was not suitable for developing very large applications, he concluded that Turbo Pascal "is well written, fun to use at times, and fast enough to make up for its few shortcomings ... it is a bargain that shouldn't be passed up". A second called the DOS version "without doubt, the best software value I have ever purchased", while a third said that Borland "deserves praise for" the "high-value" CP/M version. [ 13 ]
Also in July 1984, Creative Computing favorably compared Turbo Pascal to what the reviewer described as mediocre and expensive Pascals from UCSD, IBM, and Microsoft. He reported converting code written in IBM Pascal in less than 30 minutes, and that "under IBM Pascal, the average program took two weeks to write. With Turbo Pascal, the average is now two days". While noting the .COM and 64 KB limitations, the reviewer approved of Turbo's close adherence to the Jensen and Wirth language standard. The documentation was, he wrote, of "above average readability" and superior to IBM Pascal's. "My only fear", the review concluded, was that "it is grossly underpriced, and I worry that people might fail to take it seriously". [ 14 ] "Turbo Pascal is the Pascal to acquire", Computer Language in September said of version 2.0. Praising its speed, extensions including PC graphics and sound, documentation, ease of using overlays, and "highly standard syntax", the magazine recommended Turbo to both new and experienced programmers. [ 15 ] PC Magazine was similarly complimentary in November, stating that "nothing like Turbo Pascal has ever existed for PC-DOS before". It praised 2.0's low price, speed, stability, ease of implementing overlays, and unusually good documentation for a compiler, and noted the existence of many utilities for Turbo Pascal from other companies. The review stated that the IDE that simplified the edit-compile-run-debug loop made Turbo Pascal accessible, like BASIC, to new programmers. [ 16 ]
Pournelle in August 1985 called version 3.0 "a distinct improvement on the already impressive version 2" and said that the new book license "seems quite fair to me". He said that "Turbo Pascal has got to be the best value in languages on the market today", and that Borland led the industry in "delivering excellent products at reasonable costs". [ 17 ] Webster also praised 3.0, stating in August 1985 that Turbo Pascal "is best known for its small size, incredible compile speeds, and fast execution times". He noted that the software's quality and low price was especially surprising after the " JRT Pascal fiasco", and stated that even at the new higher $69.95 price, it was "probably still the best software deal on the market". [ 9 ] Despite finding what the magazine called "a serious bug" in 3.0, and decreased compatibility with PC clones , Byte in February 1986 stated that "it is hard to avoid recommending Turbo to anyone who wants to program in Pascal", citing improved speed and graphic routines. [ 18 ] When reviewing four other Pascal compilers in December 1986, the magazine described Turbo Pascal 3.0 as "practical and attractive to programmers at all levels of expertise". [ 19 ]
Besides allowing applications larger than 64 KB, Byte in 1988 reported substantially faster compiling and executing for version 4.0, and that although it did not maintain previous versions' "almost total" backward compatibility, conversion was fast and easy. The reviewer concluded, "I highly recommend Turbo Pascal 4.0 as an addition to any programmer's software repertoire". [ 20 ]
Byte in 1989 listed Turbo C and Turbo Pascal as among the "Distinction" winners of the Byte Awards. Citing their user interface and continued emphasis on speed, the magazine stated that "for rapid prototyping there's not much better". [ 21 ] In the same issue Pournelle again praised version 4.0 and 5.0 of Turbo Pascal. Citing Anacreon as "a good example of how complex a program you can write in Pascal", and the many libraries from Borland and other developers, he wrote "I think it may well be the language for the rest of us". [ 22 ]
Scott MacGregor of Microsoft said that Bill Gates "couldn't understand why our stuff was so slow" compared to Turbo Pascal. "He would bring in poor Greg Whitten [programming director of Microsoft languages] and yell at him for half an hour" because their company was unable to defeat Kahn's small startup, MacGregor recalled. [ 23 ]
By 1995 Borland had dropped Turbo/Borland Pascal and replaced it with the rapid application development (RAD) environment Borland Delphi , based on Object Pascal. The 32 - and 64-bit Delphi versions still support the more portable Pascal enhancements of the earlier products (i.e., those not specific to 16-bit code) including the earlier static object model. This language backwards compatibility means much old Turbo Pascal code can still be compiled and run in a modern environment today.
Other suppliers have produced software development tools compatible with Turbo Pascal. The best-known are Free Pascal and Virtual Pascal .
This is the classic "Hello, World!" program in Turbo Pascal:
This asks for a name and writes it back to the screen a hundred times:
While all versions of Turbo Pascal could include inline machine code , starting with version 6 it was possible to integrate assembly language within Pascal source code. [ 24 ]
Support for the various x86 memory models was provided by inline assembly, compiler options, and language extensions such as the "absolute" keyword. The Turbo Assembler , TASM, a standard x86 assembler independent of TP, and source-compatible with the widely used Microsoft Macro Assembler MASM, was supplied with the enhanced "Borland Pascal" versions.
The IDE provided several debugging facilities, including single stepping , examination and changing of variables, and conditional breakpoints. In later versions assembly-language blocks could be stepped through. The user could add breakpoints on variables and registers in an IDE window. Programs using IBM PC graphics mode could flip between graphics and text mode automatically or manually, or display both on two screens. For cases where the relatively simple debugging facilities of the IDE were insufficient, Turbopower Software produced a more powerful debugger, T-Debug. [ 25 ] The same company produced Turbo Analyst and Overlay Manager for Turbo Pascal. T-Debug was later updated for Turbo Pascal 4, but discontinued with the release of Borland's Turbo Debugger (TD), which also allowed some hardware intervention on computers equipped with the new 80386 processor.
TD was usually supplied in conjunction with the Turbo Assembler and the Turbo Profiler, a code profiler that reported on the time spent in each part of the program to assist program optimisation by finding bottlenecks. [ 26 ] The books included with Borland Pascal had detailed descriptions of the Intel assembler language, including the number of clock cycles required by each instruction. Development and debugging could be carried out entirely within the IDE unless the advanced debugging facilities of Turbopower T-Debug, and later TD, were required.
Later versions also supported remote debugging via an RS-232 communication cable. [ 27 ]
Over the years, Borland enhanced not only the IDE, but also extended the programming language. A development system based on ISO standard Pascal requires implementation-specific extensions for the development of real-world applications on the platforms they target. Standard Pascal is designed to be platform-independent, so prescribes no low-level access to hardware- or operating system-dependent facilities. Standard Pascal also does not prescribe how a large program should be split into separate compiling units. From version 4, Turbo Pascal adopted the concept of units from UCSD Pascal . Units were used as external function libraries, like the object files used in other languages such as FORTRAN or C.
For example, the line uses crt; in a program included the unit called crt; the uses is the mechanism for using other compiling units. interface and implementation were the keywords used to specify, within the unit, what was (and what was not) visible outside the unit. This is similar to the public and private keywords in other languages such as C++ and Java .
Units in Borland's Pascal were similar to Modula-2 's separate compiling system. In 1987, when Turbo Pascal 4 was released, Modula-2 was making inroads as an educational language which could replace Pascal. Borland, in fact, had a Turbo Modula-2 compiler, but only released it on CP/M (its user interface was almost identical to that of Turbo Pascal 1–3) with little marketing. A much improved DOS version was developed, but as Borland was unwilling to publish the results, the authors including Niels Jensen bought the rights and formed Jensen & Partners International to publish it as JPI TopSpeed Modula-2. Instead Borland chose to implement separate compiling in their established Pascal product.
Separate compiling was not part of the standard Pascal language, but was already available in UCSD Pascal , which was very popular on 8-bit machines. Turbo Pascal syntax for units appears to have been borrowed from UCSD Pascal. [ 28 ] Earlier versions of Turbo Pascal, designed for computers with limited resources, supported a "chain and execute" system of dynamic linking for separately compiled objects, similar to the system widely used in BASIC. Also, the language had a statement to include separate source code in a program when necessary, and overlaying was supported from TP3, but, as with overlays, chained objects had to fit into the original (limited) program memory space. As computing and storage facilities advanced, the ability to generate large EXE files was added to Turbo Pascal, with the ability to statically link and collectively load separately compiled objects.
The .TPU files output by compiling a Turbo Pascal unit are tightly linked to the internal structures of the compiler, rather than standard .OBJ linkable files. This improved compiling and linking times, but meant that .TPU files could not be linked with the output of other languages or even used with different releases of Turbo Pascal unless recompiled from source.
From version 5.5 some object-oriented programming features were introduced: classes , inheritance , constructors and destructors . [ 5 ] The IDE was already augmented with an object browser interface showing relations between objects and methods and allowing programmers to navigate the modules easily. Borland called its language Object Pascal , which was greatly extended to become the language underlying Delphi (which has two separate OOP systems).
The name "Object Pascal" originated with the Pascal extensions developed by Apple Computer to program its Lisa and Macintosh computers. Pascal originator Niklaus Wirth consulted in developing these extensions, which built upon the record type already present in Pascal.
Several versions of Turbo Pascal, including the last version 7, include a unit named CRT, which was used by many fullscreen text-mode applications on a CRT . This unit contains code in its initialization section to determine the CPU speed and calibrate delay loops. This code fails on processors with a speed greater than about 200 MHz and aborts immediately with a "Runtime Error 200" message. [ 29 ] (the error code 200 had nothing to do with the CPU speed 200 MHz). This is caused because a loop runs to count the number of times it can iterate in a fixed time, as measured by the real-time clock . When Turbo Pascal was developed it ran on machines with CPUs running at 2.5 to 8 MHz, and little thought was given to the possibility of vastly higher speeds, so from about 200 MHz enough iterations can be run to overflow the 16-bit counter. [ 30 ] A patch was produced when machines became too fast for the original method, but failed as processor speeds increased yet further, and was superseded by others.
Programs subject to this error can be recompiled from source code with a compiler patched to eliminate the error (using a TURBO.TPL compiled with a corrected CRT unit) or, if source code is unavailable, executables can be patched by a tool named TPPATCH or equivalent, [ 31 ] [ 32 ] or by loading a terminate-and-stay-resident program before running the faulty program. [ 33 ]
There are also patches to the TP7 compiler, [ 34 ] thus if the Pascal source is available, a new compiling's code will work without the compiled code needing a patch. If the source code is available, porting to libraries without CPU clock speed dependency is a solution too. [ 35 ]
There were several floating point types, including single (the 4-byte [IEEE 754] representation) double (the 8-byte IEEE 754 representation), extended (a 10-byte IEEE 754 representation used mostly internally by numeric coprocessors ) and Real (a 6-byte representation).
In the early days, Real was the most popular. Most PCs of the era did not have a floating-point coprocessor so all floating-point arithmetic had to be done in software. Borland's own floating-point algorithms on Real were quicker than using the other types, though its library also emulated the other types in software.
Version 1, released on 20 November 1983, was a basic all-in-one system, working in memory and producing .COM executable files for DOS and CP/M, and equivalent .CMD executables for CP/M-86 (totally different from .CMD batch files later used in 32-bit Microsoft Windows). Source code files were limited to 64 KB to simplify the IDE, and DOS .COM files were limited to 64 KB each of code, stack and global (static) variables. Program source code could be extended by using the include facility if the source code exceeded the memory limit of the editor.
There were different versions of Turbo Pascal for computers running DOS, CP/M, or CP/M-86 with 64 KB of memory and at least one floppy disk drive. The CP/M version could run on the many CP/M machines of the time with Z80 processors, or an Apple II with Z80 card. The DOS and CP/M-86 versions ran on the many 8086 and 8088 machines which became available, including the IBM PC. The installer, lister, and compiler with its IDE, and the source code for a simple spreadsheet program called MicroCalc written by Philippe Kahn as a demonstration, would fit on a single floppy disc. A disc copy without MicroCalc would accommodate the source code and compiled executable of a reasonable-sized program—as it was common at the time for users to have only a single floppy drive as mass storage , it was a great convenience to be able to fit both the compiler and the program being written on a single disc, avoiding endless disc swapping.
The architecture of the various machines running MS-DOS additionally limited the maximum user memory to under 1 MB (e.g., machines hardware-compatible with the IBM PC were limited to 640 KB).
The Turbo Pascal IDE was very advanced for its day. It was able to perform well and compile very fast with the amount of RAM on a typical home computer. The IDE was simple and intuitive to use, and had a well-organized system of menus. Early versions of the editor used WordStar key functions, which was the de facto standard at the time. Later versions of the IDE, designed for PCs with more disk space and memory, could display the definitions of the keywords of the language by putting the cursor over a keyword and pressing the F1 key (conventionally used to display help). Many definitions included example code.
In addition to standard executable programs, the compiler could generate terminate-and-stay-resident (TSR) programs, small utilities that stayed in memory and let the computer do other tasks—running several programs at the same time, multitasking , was not otherwise available. Borland produced a small application suite called Sidekick that was a TSR letting the user keep a diary, notes, and so forth.
Version 2, released a few months later on 17 April 1984, was an incremental improvement to the original Turbo Pascal, to the point that the reference manual was at first identical to version 1's, down to having 1983 as the copyright date on some of the compiler's sample output, but had a separate "Addendum to Reference Manual: Version 2.0 and 8087 Supplement" manual with separate page numbering. [ 36 ] Additions included an overlay system , where separate overlay procedures would be automatically swapped from disk into a reserved space in memory. This memory was part of the 64kB RAM used by the program's code, and was automatically the size of the largest overlay procedure. [ 36 ] Overlay procedures could include overlay sections themselves, but unless a RAM disk was used, the resulting disk swapping could be slow. 2.0 also added the Dispose procedure to manage the heap , allowing individual dynamic variables to be freed, as an alternative to the more primitive 'Mark/Release' system and increased compatibility with WordStar commands plus use of the numeric keypad on the IBM PC and compatibles. [ 36 ] Such PCs also had new text window and CGA graphics mode commands as well as being able to use the PC's speaker for tones. Finally, DOS and CP/M-86 machines with an 8087 maths coprocessor (or later compatible) had an alternative TURBO-87 compiler available to purchase. [ 36 ] It supported the 8087's long real data types with a range of 1.67E-307 to 1.67E+308 to 14 significant figure precision but with a much greater processing speed. The manual notes that although source code for the Turbo Pascal's software real data types offering a range of 1E-63 to 1E+63 to 11 significant figures, these were incompatible at a binary level: as well as having a much larger range, the software reals took six bytes in memory and the 8087 ones were eight.
Version 2 for CP/M-80 only runs on Z80-based CP/M machines. [ 15 ]
Version 3 was released on 17 September 1986. [ 4 ] Turbo Pascal 3 supported turtle graphics . [ 37 ] In addition to the default software real numbers and 8087 edition of the compiler, Borland also offered a binary-coded decimal (BCD) version (TURBOBCD) which offered the same numeric range as real data types but to 18 significant figures. [ 4 ]
Released on 20 November 1987, [ 38 ] Version 4 was a total rewrite, with both look and feel and internal operation much changed. The compiler generated executables in .EXE format under DOS, rather than the simpler but more restricted .COM executables. The by-then obsolete CP/M and CP/M-86 operating system versions were dropped when Turbo Pascal was rewritten. Version 4 introduced units, and a full-screen text user interface with pull-down menus; earlier versions had a text-based menu screen and a separate full-screen editor. ( Microsoft Windows was still very experimental when the first version was released, and even mice were rare.) An add-on package, the Turbo Pascal Graphix Toolbox, was available for Turbo Pascal V4. [ 39 ]
Colour displays were replacing monochrome; Turbo Pascal version 5.0, released 24 August 1988, [ 38 ] introduced blue as the editor's default background color, used by Borland's DOS compilers until the end of this product line in the mid-1990s. It also added debugger support for breakpoints and watches. Later versions came in two packages with the same version number: a less expensive "Turbo" package, and a "Borland" package with enhanced capabilities and more add-ons.
This version, released on 2 May 1989, [ 38 ] introduced object-oriented programming features for the Pascal language, including concept of classes, static and dynamic objects, constructors and destructors and inheritance, which would become the basis for the Object Pascal found in Borland Delphi. The IDE uses the default blue colour scheme that would also be used on later Borland Turbo products. Other changes to IDE include the addition context-sensitive help with description of all built-in functions, and the ability to copy code fragments from the help to edit window. [ 40 ]
Version 6 was released on 23 October 1990. [ 38 ] Changes from 5.5 include: the addition of inline assembly, the addition of the Turbo Vision library, mouse support, clipboard for text manipulations, multiple document interface supporting up to nine edit windows. [ 41 ]
Version 7 was released on 27 October 1992. [ 38 ] Changes from 6.0 include support for the creation of DOS and Windows executables and Windows DLLs, and syntax highlighting. [ 42 ]
Two versions named "Turbo Pascal for Windows" (TPW), for Windows 3.x , were released: TPW 1.0, based on Turbo Pascal 6 but released about 2 years later, and 1.5, released after Turbo Pascal 7; they were succeeded by Borland Pascal 7, which had Windows support. The Windows compiler in Pascal 7 was titled Borland Pascal for Windows .
Both versions built Windows-compatible programs, and featured a Windows-based IDE, as opposed to the DOS-based IDE in Turbo Pascal. The IDE and editor commands conformed to the Microsoft Windows user interface guidelines instead of the classic TP user interface. The support for Windows programs required the Object Windows Library (OWL), similar but not identical to that for the first release of Borland C++ , and radically different from the earlier DOS Turbo Vision environment. Turbo Pascal was superseded for the Windows platform by Delphi ; the Delphi compiler can produce console programs and graphical user interface (GUI) applications, so that using Turbo and Borland Pascal became unnecessary.
Borland released Turbo Pascal for Macintosh in 1986. [ 43 ] [ 44 ] Much like versions 1 to 3 for other operating systems, it was written in compact assembly language and had a very powerful IDE, but no good debugger. Borland did not support this product very well, although they issued a version 1.1, patched to run on the 32-bit Macintosh II . Macintosh support was dropped soon after. [ citation needed ]
Borland released several versions of Turbo Pascal as freeware after they became "antique software", [ 45 ] with 1.0 for DOS on 1 February 2000, 3.02 on 10 February 2000, 5.5 on 21 February 2002, Turbo Pascal 7.01 French version in year 2000. [ 46 ] Most of the downloads are still available on the successor website of Embarcadero Technologies . [ 3 ] [ 4 ] [ 5 ] | https://en.wikipedia.org/wiki/Runtime_Error_200 |
In computer programming , a runtime system or runtime environment is a sub-system that exists in the computer where a program is created, as well as in the computers where the program is intended to be run. The name comes from the compile time and runtime division from compiled languages , which similarly distinguishes the computer processes involved in the creation of a program (compilation) and its execution in the target machine (the runtime). [ 1 ]
Most programming languages have some form of runtime system that provides an environment in which programs run. This environment may address a number of issues including the management of application memory , how the program accesses variables , mechanisms for passing parameters between procedures , interfacing with the operating system (OS), among others. The compiler makes assumptions depending on the specific runtime system to generate correct code. Typically the runtime system will have some responsibility for setting up and managing the stack and heap , and may include features such as garbage collection , threads or other dynamic features built into the language. [ 1 ]
Every programming language specifies an execution model , and many implement at least part of that model in a runtime system. One possible definition of runtime system behavior, among others, is "any behavior not directly attributable to the program itself". This definition includes putting parameters onto the stack before function calls, parallel execution of related behaviors, and disk I/O .
By this definition, essentially every language has a runtime system, including compiled languages , interpreted languages , and embedded domain-specific languages . Even API -invoked standalone execution models, such as Pthreads ( POSIX threads ), have a runtime system that implements the execution model's behavior.
Most scholarly papers on runtime systems focus on the implementation details of parallel runtime systems. A notable example of a parallel runtime system is Cilk , a popular parallel programming model. [ 2 ] The proto-runtime toolkit was created to simplify the creation of parallel runtime systems. [ 3 ]
In addition to execution model behavior, a runtime system may also perform support services such as type checking , debugging , or code generation and optimization . [ 4 ]
The runtime system is also the gateway through which a running program interacts with the runtime environment . The runtime environment includes not only accessible state values, but also active entities with which the program can interact during execution. For example, environment variables are features of many operating systems, and are part of the runtime environment; a running program can access them via the runtime system. Likewise, hardware devices such as disks or DVD drives are active entities that a program can interact with via a runtime system.
One unique application of a runtime environment is its use within an operating system that only allows it to run. In other words, from boot until power-down, the entire OS is dedicated to only the application(s) running within that runtime environment. Any other code that tries to run, or any failures in the application(s), will break the runtime environment. Breaking the runtime environment in turn breaks the OS, stopping all processing and requiring a reboot. If the boot is from read-only memory, an extremely secure, simple, single-mission system is created.
Examples of such directly bundled runtime systems include:
The runtime system of the C language is a particular set of instructions inserted by the compiler into the executable image. Among other things, these instructions manage the process stack, create space for local variables, and copy function call parameters onto the top of the stack.
There are often no clear criteria for determining which language behaviors are part of the runtime system itself and which can be determined by any particular source program. For example, in C, the setup of the stack is part of the runtime system. It is not determined by the semantics of an individual program because the behavior is globally invariant: it holds over all executions. This systematic behavior implements the execution model of the language, as opposed to implementing semantics of the particular program (in which text is directly translated into code that computes results).
This separation between the semantics of a particular program and the runtime environment is reflected by the different ways of compiling a program: compiling source code to an object file that contains all the functions versus compiling an entire program to an executable binary. The object file will only contain assembly code relevant to the included functions, while the executable binary will contain additional code that implements the runtime environment. The object file, on one hand, may be missing information from the runtime environment that will be resolved by linking . On the other hand, the code in the object file still depends on assumptions in the runtime system; for example, a function may read parameters from a particular register or stack location, depending on the calling convention used by the runtime environment.
Another example is the case of using an application programming interface (API) to interact with a runtime system. The calls to that API look the same as calls to a regular software library , however at some point during the call the execution model changes. The runtime system implements an execution model different from that of the language the library is written in terms of. A person reading the code of a normal library would be able to understand the library's behavior by just knowing the language the library was written in. However, a person reading the code of the API that invokes a runtime system would not be able to understand the behavior of the API call just by knowing the language the call was written in. At some point, via some mechanism, the execution model stops being that of the language the call is written in and switches over to being the execution model implemented by the runtime system. For example, the trap instruction is one method of switching execution models. This difference is what distinguishes an API-invoked execution model, such as Pthreads, from a usual software library. Both Pthreads calls and software library calls are invoked via an API, but Pthreads behavior cannot be understood in terms of the language of the call. Rather, Pthreads calls bring into play an outside execution model, which is implemented by the Pthreads runtime system (this runtime system is often the OS kernel).
As an extreme example, the physical CPU itself can be viewed as an implementation of the runtime system of a specific assembly language. In this view, the execution model is implemented by the physical CPU and memory systems. As an analogy, runtime systems for higher-level languages are themselves implemented using some other languages. This creates a hierarchy of runtime systems, with the CPU itself—or actually its logic at the microcode layer or below—acting as the lowest-level runtime system.
Some compiled or interpreted languages provide an interface that allows application code to interact directly with the runtime system. An example is the Thread class in the Java language . The class allows code (that is animated by one thread) to do things such as start and stop other threads. Normally, core aspects of a language's behavior such as task scheduling and resource management are not accessible in this fashion.
Higher-level behaviors implemented by a runtime system may include tasks such as drawing text on the screen or making an Internet connection. It is often the case that operating systems provide these kinds of behaviors as well, and when available, the runtime system is implemented as an abstraction layer that translates the invocation of the runtime system into an invocation of the operating system. This hides the complexity or variations in the services offered by different operating systems. This also implies that the OS kernel can itself be viewed as a runtime system, and that the set of OS calls that invoke OS behaviors may be viewed as interactions with a runtime system.
In the limit, the runtime system may provide services such as a P-code machine or virtual machine , that hide even the processor's instruction set . This is the approach followed by many interpreted languages such as AWK , and some languages like Java , which are meant to be compiled into some machine-independent intermediate representation code (such as bytecode ). This arrangement simplifies the task of language implementation and its adaptation to different machines, and improves efficiency of sophisticated language features such as reflective programming . It also allows the same program to be executed on any machine without an explicit recompiling step, a feature that has become very important since the proliferation of the World Wide Web . To speed up execution, some runtime systems feature just-in-time compilation to machine code.
A modern aspect of runtime systems is parallel execution behaviors, such as the behaviors exhibited by mutex constructs in Pthreads and parallel section constructs in OpenMP . A runtime system with such parallel execution behaviors may be modularized according to the proto-runtime approach.
Notable early examples of runtime systems are the interpreters for BASIC and Lisp . These environments also included a garbage collector . Forth is an early example of a language designed to be compiled into intermediate representation code; its runtime system was a virtual machine that interpreted that code. Another popular, if theoretical, example is Donald Knuth 's MIX computer.
In C and later languages that supported dynamic memory allocation, the runtime system also included a library that managed the program's memory pool.
In the object-oriented programming languages , the runtime system was often also responsible for dynamic type checking and resolving method references. | https://en.wikipedia.org/wiki/Runtime_system |
In aviation , a runway is an elongated, rectangular surface designed for the landing and takeoff of an aircraft . [ 1 ] Runways may be a human-made surface (often asphalt , concrete , or a mixture of both) or a natural surface ( grass , dirt , gravel , ice , sand or salt ). Runways, taxiways and ramps , are sometimes referred to as "tarmac", though very few runways are built using tarmac . Takeoff and landing areas defined on the surface of water for seaplanes are generally referred to as waterways . Runway lengths are now commonly given in meters worldwide , except in North America where feet are commonly used. [ 2 ]
In 1916, in a World War I war effort context, the first concrete-paved runway was built in Clermont-Ferrand in France , allowing local company Michelin to manufacture Bréguet Aviation military aircraft. [ citation needed ]
In January 1919, aviation pioneer Orville Wright underlined the need for "distinctly marked and carefully prepared landing places, [but] the preparing of the surface of reasonably flat ground [is] an expensive undertaking [and] there would also be a continuous expense for the upkeep." [ 3 ]
The primary consideration in determining runway orientation is the prevailing wind direction, in lieu of spatial constraints or obstructions that may prevent optimal alignment. To mitigate the occurrence of crosswind operations which are more challenging and dangerous, runways at airports are designed to align with the wind’s direction. Utilizing runways oriented with the wind direction also allows for aircraft to take-off and land into the headwind, reducing the length of runway used during operations. Taking off and landing into the wind increases the relative air speed of the aircraft to create more lift; this allows aircraft to reach take-off velocity with a shorter amount of ground roll and also allows aircraft to land with a slower ground speed. To determine the prevailing wind directions, analysis of a wind rose is used before constructing airport runways. [ 4 ]
Originally in the 1920s and 1930s, airports and air bases (particularly in the United Kingdom) were built in a triangle-like pattern of three runways at 60° angles to each other. The reason was that aviation was only starting, and although it was known that wind affected the runway distance required, not much was known about wind behaviour. [ citation needed ] As a result, three runways in a triangle-like pattern were built, and the runway with the heaviest traffic would eventually expand into the airport's main runway, while the other two runways would be either abandoned or converted into taxiways. [ 5 ]
Runways are named by a number between 01 and 36, which is generally the magnetic azimuth of the runway's heading in deca degrees . This heading differs from true north by the local magnetic declination . A runway numbered 09 points east (90°), runway 18 is south (180°), runway 27 points west (270°) and runway 36 points to the north (360° rather than 0°). [ 6 ] When taking off from or landing on runway 09, a plane is heading around 90° (east). A runway can normally be used in both directions, and is named for each direction separately: e.g., "runway 15" in one direction is "runway 33" when used in the other. The two numbers differ by 18 (= 180°). For clarity in radio communications, each digit in the runway name is pronounced individually: runway one-five, runway three-three, etc. (instead of "fifteen" or "thirty-three").
A leading zero, for example in "runway zero-six" or "runway zero-one-left", is included for all ICAO and some U.S. military airports (such as Edwards Air Force Base ). However, most U.S. civil aviation airports drop the leading zero as required by FAA regulation. [ 7 ] This also includes some military airfields such as Cairns Army Airfield . This American anomaly may lead to inconsistencies in conversations between American pilots and controllers in other countries.
Military airbases may include smaller paved runways known as "assault strips" for practice and training next to larger primary runways. [ 8 ] These strips eschew the standard numerical naming convention and instead employ the runway's full three digit heading; examples include Dobbins Air Reserve Base 's Runway 110/290 and Duke Field 's Runway 180/360. [ 9 ] [ 10 ]
Runways with non-hard surfaces, such as small turf airfields and waterways for seaplanes , may use the standard numerical scheme or may use traditional compass point naming, examples include Ketchikan Harbor Seaplane Base 's Waterway E/W. [ 11 ] [ 12 ] Airports with unpredictable or chaotic water currents, such as Santa Catalina Island 's Pebbly Beach Seaplane Base, may designate their landing area as Waterway ALL/WAY to denote the lack of designated landing direction. [ 13 ] [ 12 ]
If there is more than one runway pointing in the same direction (parallel runways), each runway is identified by appending left (L), center (C) and right (R) to the end of the runway number to identify its position (when facing its direction)—for example, runways one-five-left (15L), one-five-center (15C), and one-five-right (15R). Runway zero-three-left (03L) becomes runway two-one-right (21R) when used in the opposite direction (derived from adding 18 to the original number for the 180° difference when approaching from the opposite direction). In some countries, regulations mandate that where parallel runways are too close to each other, only one may be used at a time under certain conditions (usually adverse weather ).
At large airports with four or more parallel runways (for example, at Chicago O'Hare , Los Angeles , Detroit Metropolitan Wayne County , Hartsfield-Jackson Atlanta , Denver , Dallas–Fort Worth and Orlando ), some runway identifiers are shifted by 1 to avoid the ambiguity that would result with more than three parallel runways. For example, in Los Angeles, this system results in runways 6L, 6R, 7L, and 7R, even though all four runways are actually parallel at approximately 69°. At Dallas/Fort Worth International Airport , there are five parallel runways, named 17L, 17C, 17R, 18L, and 18R, all oriented at a heading of 175.4°. Occasionally, an airport with only three parallel runways may use different runway identifiers, such as when a third parallel runway was opened at Phoenix Sky Harbor International Airport in 2000 to the south of existing 8R/26L—rather than confusingly becoming the "new" 8R/26L it was instead designated 7R/25L, with the former 8R/26L becoming 7L/25R and 8L/26R becoming 8/26.
Suffixes may also be used to denote special-use runways. Airports that have seaplane waterways may choose to denote the waterway on charts with the suffix W; such as Daniel K. Inouye International Airport in Honolulu and Lake Hood Seaplane Base in Anchorage . [ 14 ] Small airports that host various forms of air traffic may employ additional suffixes to denote special runway types based on the type of aircraft expected to use them, including STOL aircraft (S), gliders (G), rotorcraft (H), and ultralights (U). [ 12 ] Runways that are numbered relative to true north rather than magnetic north will use the suffix T; this is advantageous for certain airfields in the far north such as Thule Air Base (08T/26T). [ 15 ]
Runway designations may be changed over time as the Earth's magnetic field shifts and their headings shift with it. This is more common at higher latitudes: for example, Fairbanks International Airport in Alaska renames runways roughly every 24 years, most recently in 2009. [ 16 ] In northern Canada, [ 17 ] runways are designated based on true north, which avoids the need to update them. [ 18 ] Nav Canada , Canada's air navigation service provider, has advocated for an industry-wide switch to true north. [ 19 ]
As runways are designated with headings rounded to the nearest 10°, some runways are affected sooner than others; e.g. a hypothetical Runway 23 with a heading of 226° would only have to shift to 224° to become Runway 22. Because magnetic drift itself is slow, these changes are uncommon, and not welcomed, as they require accompanying changes in aeronautical charts and descriptive documents. When a runway designation does change, it is often done at night, especially at major airports, because taxiway signs need to be changed and the numbers at each end of the runway need to be repainted to the new runway designators. [ citation needed ] In 2009 for example, London Stansted Airport in the United Kingdom changed its runway designation from 05/23 to 04/22 during the night. [ 20 ]
Runway dimensions vary from as small as 245 m (804 ft) long and 8 m (26 ft) wide in smaller general aviation airports, to 5,500 m (18,045 ft) long and 80 m (262 ft) wide at large international airports built to accommodate the largest jets , to the huge 11,917 m × 274 m (39,098 ft × 899 ft) lake bed runway 17/35 at Edwards Air Force Base in California – developed as a landing site for the Space Shuttle . [ 21 ]
Takeoff and landing distances available are given using one of the following terms:
There are standards for runway markings. [ 27 ]
There are runway markings and signs on most large runways. Larger runways have a distance remaining sign (black box with white numbers). This sign uses a single number to indicate the remaining distance of the runway in thousands of feet. For example, a 7 will indicate 7,000 ft (2,134 m) remaining. The runway threshold is marked by a line of green lights.
There are three types of runways:
Waterways may be unmarked or marked with buoys that follow maritime notation instead. [ 33 ]
For runways and taxiways that are permanently closed, the lighting circuits are disconnected. The runway threshold, runway designation, and touchdown markings are obliterated and yellow "Xs" are placed at each end of the runway and at 1,000 ft (305 m) intervals. [ 34 ]
A line of lights on an airfield or elsewhere to guide aircraft in taking off or coming in to land or an illuminated runway is sometimes also known as a flare path .
Runway lighting is used at airports during periods of darkness and low visibility. Seen from the air, runway lights form an outline of the runway. A runway may have some or all of the following: [ 36 ]
According to Transport Canada 's regulations, [ 37 ] the runway-edge lighting must be visible for at least 2 mi (3 km). Additionally, a new system of advisory lighting, runway status lights , is currently being tested in the United States. [ 38 ]
The edge lights must be arranged such that:
Typically the lights are controlled by a control tower , a flight service station or another designated authority. Some airports/airfields (particularly uncontrolled ones ) are equipped with pilot-controlled lighting , so that pilots can temporarily turn on the lights when the relevant authority is not available. [ 40 ] This avoids the need for automatic systems or staff to turn the lights on at night or in other low visibility situations. This also avoids the cost of having the lighting system on for extended periods. Smaller airports may not have lighted runways or runway markings. Particularly at private airfields for light planes, there may be nothing more than a windsock beside a landing strip.
Types of runway safety incidents include:
The choice of material used to construct the runway depends on the use and the local ground conditions. For a major airport, where the ground conditions permit, the most satisfactory type of pavement for long-term minimum maintenance is concrete . Although certain airports have used reinforcement in concrete pavements, this is generally found to be unnecessary, with the exception of expansion joints across the runway where a dowel assembly, which permits relative movement of the concrete slabs, is placed in the concrete. Where it can be anticipated that major settlements of the runway will occur over the years because of unstable ground conditions, it is preferable to install asphalt concrete surface, as it is easier to patch on a periodic basis. Fields with very low traffic of light planes may use a sod surface. Some runways make use of salt flats.
For pavement designs, borings are taken to determine the subgrade condition, and based on the relative bearing capacity of the subgrade, the specifications are established. For heavy-duty commercial aircraft, the pavement thickness, no matter what the top surface, varies from 10 to 48 in (25 to 122 cm), including subgrade.
Airport pavements have been designed by two methods. The first, Westergaard , is based on the assumption that the pavement is an elastic plate supported on a heavy fluid base with a uniform reaction coefficient known as the K value . Experience has shown that the K values on which the formula was developed are not applicable for newer aircraft with very large footprint pressures.
The second method is called the California bearing ratio and was developed in the late 1940s. It is an extrapolation of the original test results, which are not applicable to modern aircraft pavements or to modern aircraft landing gear . Some designs were made by a mixture of these two design theories. A more recent method is an analytical system based on the introduction of vehicle response as an important design parameter. Essentially it takes into account all factors, including the traffic conditions, service life, materials used in the construction, and, especially important, the dynamic response of the vehicles using the landing area.
Because airport pavement construction is so expensive, manufacturers aim to minimize aircraft stresses on the pavement. Manufacturers of the larger planes design landing gear so that the weight of the plane is supported on larger and more numerous tires. Attention is also paid to the characteristics of the landing gear itself, so that adverse effects on the pavement are minimized. Sometimes it is possible to reinforce a pavement for higher loading by applying an overlay of asphaltic concrete or portland cement concrete that is bonded to the original slab. Post-tensioning concrete has been developed for the runway surface. This permits the use of thinner pavements and should result in longer concrete pavement life. Because of the susceptibility of thinner pavements to frost heave , this process is generally applicable only where there is no appreciable frost action .
Runway pavement surface is prepared and maintained to maximize friction for wheel braking. To minimize hydroplaning following heavy rain, the pavement surface is usually grooved so that the surface water film flows into the grooves and the peaks between grooves will still be in contact with the aircraft tyres. To maintain the macrotexturing built into the runway by the grooves, maintenance crews engage in airfield rubber removal or hydrocleaning in order to meet required FAA , or other aviation authority friction levels.
Subsurface underdrains help provide extended life and excellent and reliable pavement performance. At the Hartsfield Atlanta, GA airport the underdrains usually consist of trenches 18 in (46 cm) wide and 48 in (120 cm) deep from the top of the pavement. A perforated plastic tube (5.9 in (15 cm) in diameter) is placed at the bottom of the ditch. The ditches are filled with gravel size crushed stone. [ 41 ] Excessive moisture under a concrete pavement can cause pumping, cracking, and joint failure. [ 42 ]
In aviation charts, the surface type is usually abbreviated to a three-letter code.
The most common hard surface types are asphalt and concrete. The most common soft surface types are grass and gravel.
A runway of at least 1,800 m (5,900 ft) in length is usually adequate for aircraft weights below approximately 100,000 kg (220,000 lb). Larger aircraft including widebodies will usually require at least 2,400 m (7,900 ft) at sea level. International widebody flights, which carry substantial amounts of fuel and are therefore heavier, may also have landing requirements of 3,200 m (10,500 ft) or more and takeoff requirements of 4,000 m (13,000 ft). The Boeing 747 is considered to have the longest takeoff distance of the more common aircraft types and has set the standard for runway lengths of larger international airports. [ 43 ]
At sea level , 3,200 m (10,500 ft) can be considered an adequate length to land virtually any aircraft. For example, at O'Hare International Airport , when landing simultaneously on 4L/22R and 10/28 or parallel 9R/27L, it is routine for arrivals from East Asia , which would normally be vectored for 4L/22R (2,300 m (7,546 ft)) or 9R/27L (2,400 m (7,874 ft)) to request 28R (4,000 m (13,123 ft)). It is always accommodated, although occasionally with a delay. Another example is that the Luleå Airport in Sweden was extended to 3,500 m (11,483 ft) to allow any fully loaded freight aircraft to take off. These distances are also influenced by the runway grade (slope) such that, for example, each 1 percent of runway down slope increases the landing distance by 10 percent. [ 44 ]
An aircraft taking off at a higher altitude must do so at reduced weight due to decreased density of air at higher altitudes, which reduces engine power and wing lift. An aircraft must also take off at a reduced weight in hotter or more humid conditions (see density altitude ). In the worst case, this is colloquially referred to as hot and high operation, among the most challenging conditions for takeoff performance. Most commercial aircraft carry manufacturer's tables showing the adjustments required for a given temperature. | https://en.wikipedia.org/wiki/Runway |
Runway safety is concerned with reducing harm that could occur on an aircraft runway . Safety means avoiding incorrect presence ( incursion ) of aircraft, inappropriate exits ( excursion ) and use of the wrong runway due to confusion. The runway condition is a runway's current status due to meteorological conditions and air safety. [ 1 ]
Several terms fall under the flight safety topic of runway safety, including incursion, excursion, and confusion. [ 2 ]
Runway incursion involves an aircraft, and a second aircraft, vehicle, or person. It is defined by ICAO and the U.S. FAA as "Any occurrence at an aerodrome involving the incorrect presence of an aircraft, vehicle or person on the protected area of a surface designated for the landing and take off of aircraft." [ 3 ] [ 4 ]
Runway excursion is an incident involving only a single aircraft, where it makes an inappropriate exit from the runway. This can happen because of pilot error, poor weather, or a fault with the aircraft. [ 5 ] A runway overrun is a type of excursion where the aircraft is unable to stop before the end of the runway.
Runway excursion is the most frequent type of landing accident, slightly ahead of runway incursion. [ 6 ] For runway accidents recorded between 1995 and 2007, 96% were of the 'excursion' type. [ 6 ]
Runway confusion is when a single aircraft uses the wrong runway, or a taxiway , for takeoff or landing. [ 7 ] Runway confusions are considered a subset of runway incursions. Three major factors that increase the risk of runway confusion include airport complexity, close proximity of runway thresholds, and joint use of a runway as a taxiway. [ 8 ] Examples of runway confusion incidents include Singapore Airlines Flight 006 , Comair Flight 5191 and Air Canada Flight 759 .
The U.S. FAA publishes an annual report on runway safety issues, available from the FAA website. [ 4 ] [ 9 ] [ 10 ] New systems designed to improve runway safety, such as Airport Movement Area Safety System (AMASS) and Runway Awareness and Advisory System (RAAS), are discussed in the report. AMASS narrowly prevented a serious collision in the 2007 San Francisco International Airport runway incursion .
In the 1990s, the U.S. FAA conducted a study about a civilian version of 3D military thrust vectoring to prevent jetliner catastrophes [ 11 ]
Some instruments for runway safety include ILS , LLWAS , microwave landing system , transponder landing system , Runway Awareness and Advisory System , and airport surveillance and broadcast systems .
The "runway condition" is a runway's current status in relation to current meteorological conditions and air safety.
According to the JAR definition, a runway with water patches or that is flooded is considered to be contaminated.
Takeoff and Landing Performance Assessment (TALPA) was introduced in 2016, whereby airport operators report Runway Condition Codes (RWYCC) for take-off and landing.
In response to an increase in runway incursions, the Federal Aviation Administration (FAA) launched several initiatives aimed at improving runway safety. One notable effort is the Runway Incursion Mitigation (RIM) program, which focuses on identifying and addressing specific risk factors at airports with a history of incursions. This program has successfully mitigated risks at numerous locations by enhancing signage, improving taxiway markings, and reconfiguring airport layouts to reduce confusion among pilots and ground vehicles. As of 2023, the FAA has identified 131 unmitigated RIM locations across 80 airports and has implemented mitigation strategies at 99 of these sites, resulting in a significant reduction in runway incursions [ 12 ] | https://en.wikipedia.org/wiki/Runway_safety |
Ruppeiner geometry is thermodynamic geometry (a type of information geometry ) using the language of Riemannian geometry to study thermodynamics . George Ruppeiner proposed it in 1979. He claimed that thermodynamic systems can be represented by Riemannian geometry, and that statistical properties can be derived from the model.
This geometrical model is based on the inclusion of the theory of fluctuations into the axioms of equilibrium thermodynamics , namely, there exist equilibrium states which can be represented by points on two-dimensional surface (manifold) and the distance between these equilibrium states is related to the fluctuation between them. This concept is associated to probabilities, i.e. the less probable a fluctuation between states, the further apart they are. This can be recognized if one considers the metric tensor g ij in the distance formula (line element) between the two equilibrium states
where the matrix of coefficients g ij is the symmetric metric tensor which is called a Ruppeiner metric , defined as a negative Hessian of the entropy function
where U is the internal energy (mass) of the system and N a refers to the extensive parameters of the system. Mathematically, the Ruppeiner geometry is one particular type of information geometry and it is similar to the Fisher–Rao metric used in mathematical statistics.
The Ruppeiner metric can be understood as the thermodynamic limit (large systems limit) of the more general Fisher information metric . [ 1 ] For small systems (systems where fluctuations are large), the Ruppeiner metric may not exist, as second derivatives of the entropy are not guaranteed to be non-negative.
The Ruppeiner metric is conformally related to the Weinhold metric via
where T is the temperature of the system under consideration. Proof of the conformal relation can be easily done when one writes down the first law of thermodynamics ( dU = TdS + ...) in differential form with a few manipulations. The Weinhold geometry is also considered as a thermodynamic geometry. It is defined as a Hessian of the internal energy with respect to entropy and other extensive parameters.
It has long been observed that the Ruppeiner metric is flat for systems with noninteracting underlying statistical mechanics such as the ideal gas. Curvature singularities signal critical behaviors. In addition, it has been applied to a number of statistical systems including Van der Waals gas. Recently the anyon gas has been studied using this approach.
This geometry has been applied to black hole thermodynamics , with some physically relevant results. The most physically significant case is for the Kerr black hole in higher dimensions, where the curvature singularity signals thermodynamic instability, as found earlier by conventional methods.
The entropy of a black hole is given by the well-known Bekenstein–Hawking formula
where k B {\displaystyle k_{\text{B}}} is the Boltzmann constant , c {\displaystyle c} is the speed of light , G {\displaystyle G} is the Newtonian constant of gravitation and A {\displaystyle A} is the area of the event horizon of the black hole. Calculating the Ruppeiner geometry of the black hole's entropy is, in principle, straightforward, but it is important that the entropy should be written in terms of extensive parameters,
where M {\displaystyle M} is ADM mass of the black hole and N a are the conserved charges and a runs from 1 to n . The signature of the metric reflects the sign of the hole's specific heat . For a Reissner–Nordström black hole , the Ruppeiner metric has a Lorentzian signature which corresponds to the negative heat capacity it possess, while for the BTZ black hole , we have a Euclidean signature. This calculation cannot be done for the Schwarzschild black hole, because its entropy is
which renders the metric degenerate. | https://en.wikipedia.org/wiki/Ruppeiner_geometry |
A rupture disc , also known as a pressure safety disc , burst disc , bursting disc , or burst diaphragm , is a non-reclosing pressure relief safety device that, in most uses, protects a pressure vessel , equipment or system from overpressurization or potentially damaging vacuum conditions.
A rupture disc is a type of sefe device because it has a one-time-use membrane that fails at a predetermined differential pressure, either positive or vacuum and at a coincident temperature. The membrane is usually made out of metal, [ 1 ] but nearly any material (or different materials in layers) can be used to suit a particular application. Rupture discs provide instant response (within milliseconds or microseconds in very small sizes) to an increase or decrease in system pressure, but once the disc has ruptured it will not reseal. Major advantages of the application of rupture discs compared to using pressure relief valves include leak-tightness, cost, response time, size constraints, flow area, and ease of maintenance.
Rupture discs are commonly used in petrochemical , aerospace , aviation , defense, medical, railroad , nuclear , chemical , pharmaceutical , food processing and oil field applications. They can be used as single protection devices or as a secondary relief device for a conventional safety valve ; if the pressure increases and the safety valve fails to operate or can not relieve enough pressure fast enough, the rupture disc will burst. Rupture discs are very often used in combination with safety relief valves, isolating the valves from the process, thereby saving on valve maintenance and creating a leak-tight pressure relief solution. It is sometimes possible and preferable for highest reliability, though at higher initial cost, to avoid the use of emergency pressure relief devices by developing an intrinsically safe mechanical design that provides containment in all cases.
Although commonly manufactured in disc form, the devices also are manufactured as rectangular panels ('rupture panels', 'vent panels' or explosion vents ) and used to protect buildings, enclosed conveyor systems or any very large space from overpressurization typically due to an explosion. Rupture disc sizes range from 0.125 in (3 mm) to over 4 ft (1.2 m), depending upon the industry application. Rupture discs and vent panels are constructed from carbon steel , stainless steel , hastelloy , graphite , and other materials, as required by the specific use environment.
Rupture discs are widely accepted throughout industry and specified in most global pressure equipment design codes ( American Society of Mechanical Engineers (ASME), Pressure Equipment Directive (PED), etc.). Rupture discs can be used to specifically protect installations against unacceptably high pressures or can be designed to act as one-time valves or triggering devices to initiate with high reliability and speed a sequence of actions required.
There are two rupture disc technologies used in all rupture discs, forward-acting (tension loaded) and reverse buckling (compression). Both technologies can be paired with a bursting disc indicator to provide a visual and electrical indication of failure. [ 2 ]
In the traditional forward-acting design, the loads are applied to the concave side of a domed rupture disc, stretching the dome until the tensile forces exceed the ultimate tensile stress of the material and the disc bursts. Flat rupture disc do not have a dome but, when pressure is applied, are still subject to tension loaded forces and are thus also forward-acting discs. The thickness of the raw material used in manufacturing (also known as web thickness in graphite discs) and the diameter of the disc determines the burst pressure. Most forward-acting discs are installed in systems with an 80% or lower operating ratio. [ 3 ]
In later iterations on forward-acting disc designs, precision-cut or laser scores in the material during manufacturing were used to precisely weaken the material, allowing for more variables to control of the burst pressure. This approach to rupture discs, while effective, does have limitations. Forward-acting discs are prone to metal fatigue caused by pressure cycling and operating conditions that can spike past recommended limits for the disc, causing the disc to burst at lower than its marked burst pressure. Low burst pressures also pose a problem for this disc technology. As the burst pressure lowers, the material thickness decreases. This can lead to extremely thin discs (similar to tin foil) that are highly prone to damage and have a higher chance of forming pinhole leaks due to corrosion. These discs are still successfully used today and are preferred in some situations.
Reverse buckling rupture discs are the inversion of the forward-acting disc. The dome is inverted and the pressure is now loaded on the convex side of the disc. Once the reversal threshold is met, the dome will collapse and snap through to create a dome in the opposite direction. While that is happening, the disc is opened by knife blades or points of metal located along the score line on the downstream side of the disc. By loading the reverse buckling disc in compression, it is able to resist pressure cycling or pulsating conditions. The material thickness of a reverse buckling disc is significantly higher than that of a forward-acting disc of the same size and burst pressure. The result is greater longevity, accuracy and reliability over time. Correct installation of reverse buckling discs is essential. If installed upside down, the device will act as a forward acting disc and, due to the greater material thickness, may burst at much higher than the marked burst pressure. [ 4 ]
Blowout panels , also called blow-off panels , areas with intentionally weakened structure, are used in enclosures, buildings or vehicles where a sudden overpressure may occur. By failing in a predictable manner, they channel the overpressure or pressure wave in the direction where it causes controlled, directed minimal harm, instead of causing a catastrophic failure of the structure. An alternative example is a deliberately weakened wall in a room used to store compressed gas cylinders; in the event of a fire or other accident, the tremendous energy stored in the (possibly flammable) compressed gas is directed into a "safe" direction, rather than potentially collapsing the structure in a similar manner to a thermobaric weapon .
Blow-off panels are used in ammunition compartments of some tanks to protect the crew in case of ammunition explosion, turning a catastrophic kill into a lesser firepower kill . Blowout panels are installed in several modern main battle tanks , including the M1 Abrams .
In military ammunition storage, blowout panels are included in the design of the bunkers which house explosives. Such bunkers are designed, typically, with concrete walls on four sides, and a roof made of a lighter material covered with earth. In some cases this lighter material is wood, though metal sheeting is also employed. The design is such that if an explosion or fire in the ammunition bunker (also called a locker) were to occur, the force of the blast would be directed vertically, and away from other structures and personnel.
Blowout panels had been in the past been considered as a possible solution to magazine explosions on battleships . However battleship designs since the 1920s instead used the all or nothing armor scheme , particularly with its armored citadel encompassing the battleship's vitals including machinery and magazines, and in the case of magazine penetration the only recourse is to flood the magazine. The lack of blowout panels has resulted in catastrophic damage during the magazine explosions of several battleships including Tirpitz and Yamato .
Some models of gene gun also use a rupture disc, but not as a safety device. Instead, their function is part of the normal operation of the device, allowing for precise pressure-based control of particle application to a sample. In these devices, the rupture disc is designed to fail within an optimal range of gas pressure that has been empirically associated with successful particle integration into tissue or cell culture. Different disc strengths can be available for some gene gun models. | https://en.wikipedia.org/wiki/Rupture_disc |
The Ruputer is a wristwatch computer developed in 1998 by Seiko Instruments , a subsidiary of the Seiko Group . It was introduced on 10 June 1998. [ 1 ] In the US, it was later marketed as the onHand PC by Matsucom.
The Ruputer has a 16-bit, 3.6 MHz processor and 2 MB of non-volatile storage memory and 128 KB of RAM . Its display is a 102×64 pixel monochrome LCD . Its main forms of input are a tiny 8-direction joystick and 6 function buttons. It also has a serial interface and an IR port for communicating with other devices. The main body of the device (separate from the strap) is roughly 2 inches wide, 1 1/8 inches across, and 5/8 of an inch deep. It is powered by two high-powered watch batteries, which supply the device enough energy for approximately 30 hours of use. Under normal conditions, the watch goes into standby mode down when not in use in order to extend its battery life. The device was distributed with a software development kit which allows for creation of new software written in the programming language C .
The successor to the Ruputer is the onHand PC. The onHand PC was available in two color styles, clear & black, and a single format. While the Ruputer was available with either 512 KB of storage (original Ruputer), 2 MB (Ruputer PRO), or 4 MB of flash memory (Ruputer PRO4), the onHand PC came only in a single version with 2 MB of storage. The operating system is known as W-PS-DOS version 1.16. The device features both an icon-based GUI and a text-based user interface. There is 128 KB of RAM , with an additional 128 KB of ROM .
On the device, data can be entered by two methods: The first method is by using the joystick mounted to the front of the watch itself (a method that has been considered clumsy). The second method is by synchronizing data from a full-sized PC using the included software. A program called HandySurf also allows synchronizing internet content (such as Yahoo! News Headlines).
Communication with other devices is either through a 38,400- bit/s serial port dock, or through the 9,600 infrared link, the transmitter of which is mounted to the upper middle of the watch. It is possible to link two onHands via this infrared link to play various two-player games. [ 2 ]
The watch uses two lithium CR2025 button cells for power, which can be accessed from the back of the device. The batteries give the user an average 3 months of usage before battery replacement. Many users have found that the CR2032 cells fit, which give the device a longer run time. The device's screen is a 102x64 STN 4-greyscale LCD which uses a timed backlight to save power.
The device weighs about 52 grams (1.8 ounces), similar that of a large electronic standard watch.
Considering the type of system there is a fair amount of software available, although some of the programs written for the Ruputer are either entirely in Kanji script or will not run due to the increased speed of the onHand's processor. [ citation needed ]
One developer has made a prototype for a docking station for the watch that includes a screen illuminator and a half-keyboard. This is not a commercial product, but instructions are available as to how to create such a device.
The onHand PC was discontinued by Matsucom on April 7, 2006.
The Ruputer and onHand PC failed to achieve widespread success, for a number of reasons. First, their screen is too small to display more than a handful of text, making it awkward to view data. Second, their joystick input requires entering text in a process similar to that of entering one's initials in an arcade game high-score list. Finally, they run through their non-rechargeable batteries more swiftly than is convenient for a device meant to be worn as a timepiece, although it was later found that the slightly larger CR2032 battery can be used which gives substantially better battery life.
The main competitor for the onHand PC was the Fossil Wrist PDA , a wristwatch-sized PDA . The device runs Palm OS 4.1., and like other Palm OS devices, has a virtual keyboard and touch-sensitive screen with handwriting recognition, giving the Wrist PDA an advantage over the joystick input on the onHand PC. The Wrist PDA features 8 MB of memory, four times the memory in the onHand, although a major disadvantage of the Fossil device was volatile memory - if the battery died, data was lost. The Ruputer/onHand uses non-volatile storage, which is not battery-dependent, so data is retained even through battery death. | https://en.wikipedia.org/wiki/Ruputer |
In general, a rural area or a countryside is a geographic area that is located outside towns and cities . [ 1 ] Typical rural areas have a low population density and small settlements. Agricultural areas and areas with forestry are typically described as rural, as well as other areas lacking substantial development. Different countries have varying definitions of rural for statistical and administrative purposes.
Rural areas have unique economic and social dynamics due to their relationship with land-based industry such as agriculture , forestry , and resource extraction . Rural economics can be subject to boom and bust cycles and vulnerable to extreme weather or natural disasters, such as droughts . These dynamics alongside larger economic forces encouraging urbanization have led to significant demographic declines, called rural flight , where economic incentives encourage younger populations to go to cities for education and access to jobs, leaving older, less educated and less wealthy populations in the rural areas. Slower economic development results in poorer services like healthcare, education, and infrastructure. This cycle of poverty contributes to why three quarters of the global impoverished live in rural areas according to the Food and Agricultural Organization .
Some communities have successfully encouraged economic development in rural areas , with policies such as increased access to electricity or internet . Historically, development policies have focused on larger extractive industries , such as mining and forestry. However, recent approaches more focused on sustainable development take into account economic diversification in these communities.
In Canada, the Organization for Economic Co-operation and Development defines a "predominantly rural region" as having more than 50% of the population living in rural communities where a " rural community " has a population density less than 150 people per square kilometre. In Canada, the census division has been used to represent "regions" and census consolidated sub-divisions have been used to represent "communities". Intermediate regions have 15 to 49 percent of their population living in a rural community. Predominantly urban regions have less than 15 percent of their population living in a rural community. Predominantly rural regions are classified as rural metro-adjacent, rural non-metro-adjacent and rural northern, following Philip Ehrensaft and Jennifer Beeman (1992). Rural metro-adjacent regions are predominantly rural census divisions which are adjacent to metropolitan centres while rural non-metro-adjacent regions are those predominantly rural census divisions which are not adjacent to metropolitan centres. Rural northern regions are predominantly rural census divisions that are found either entirely or mostly above the following lines of latitude in each province: Newfoundland and Labrador , 50th; Manitoba , 53rd; Alberta , British Columbia , Ontario , Quebec , and Saskatchewan , 54th. As well, rural northern regions encompass all of the Yukon , Northwest Territories and Nunavut .
Statistics Canada defines rural areas by their population counts. This has referred to the population living outside settlements of 1,000 or fewer inhabitants. The current definition states that census rural is the population outside settlements with fewer than 1,000 inhabitants and a population density below 400 people per square kilometre.
Rural areas in the United States , often referred to as rural America, [ 2 ] consist of approximately 97% of the United States ' land area. An estimated 60 million people, or one in five residents (17.9% of the total U.S. population ), live in rural America. Definitions vary from different parts of the United States government as to what constitutes those areas.
In Brazil, there are different notions of "rural area" and "countryside". Rural areas are any place outside a municipality's urban development (buildings, streets) and it is carried by informal usage. Otherwise, countryside ( interior in Portuguese ) are officially defined as all municipalities outside the state/territory capital's metropolitan region. Some states as Mato Grosso do Sul do not have any metropolitan regions, thus all of the state, except its capital is officially countryside. Rio de Janeiro is singular in Brazil and it is de facto a metropolitan state, as circa 70% of its population are located in Greater Rio . In the Federal District it is not applicable and there is no countryside as all of it is treated as the federal capital. Brasília is nominally the capital, but the capitality is shared through all Federal District, because Brazil de facto defines its capital as a municipality, and in municipal matters, the Federal District is treated and governs as a single municipality, city-state -like (Brasília, DF).
15% of the French population lives in rural areas, spread over 90% of the country. The government under President Emmanuel Macron launched an action plan in 2019 amid the yellow vests movement in favor of rural areas named the "Agenda Rural". [ 3 ] Among many initiatives recommended to redynamize rural areas, energy transition is one of them. Research is being carried out to assess the impact of new projects in rural areas. [ 4 ]
In 2018, the government had launched the "Action Cœur de Ville" program to revitalize town centers across the country. 222 towns were selected as part of the five-year program. One of the program's aims is to make the towns attractive so the areas nearby can also benefit from investments. [ 5 ]
Germany is divided into 402 administrative districts, 295 rural districts and 107 urban districts. As one of the largest agricultural producers in the European Union , more than half of Germany's territory which is almost 19 million hectares, [ 6 ] is used for farming, and located in the rural areas. Almost 10% of people in Germany have jobs related to the agricultural, forest and fisheries sectors; approximately a fifth of them are employed in the primary production. Since there is a policy of equal living conditions, people see rural areas as equivalent as urban areas. Village renewal is an approach to develop countryside and supports the challenges faced in the process of it. [ 7 ]
In Britain, there are various definitions of a rural area. [ 8 ] "Rural" is defined by the UK Department for Environment, Food and Rural Affairs (DEFRA), using population data from the latest census , such as the United Kingdom Census 2001 . [ 9 ] These definitions have various grades, but the upper point is any local government area with more than 26% of its population living in a rural settlement or market town ("market town" being defined as any settlement which has permission to hold a street market ). A number of measures are in place to protect the British countryside, including green belts .
In India a village tends to mean a small rural area, including both a settlement and its surrounding agricultural land, rather than just the settlement itself, the typical meaning elsewhere. There are said to be up to 500,000 villages in India. In rural areas, agriculture is the chief source of livelihood along with fishing , [ 10 ] cottage industries , pottery etc.
Almost every Indian economic agency today has its own definition of rural India, some of which follow:
According to the Planning Commission, a town with a maximum population of 15,000 is considered rural in nature. In these areas the panchayat makes all the decisions. There are five people in the panchayat .
The National Sample Survey Organization (NSSO) defines 'rural' as follows:
RBI defines rural areas as those areas with a population of less than 49,000 (tier -3 to tier-6 cities). [ 11 ]
It is generally said that the rural areas house up to 70% of India's population. Rural India contributes a large chunk to India's GDP by way of agriculture, self-employment, services, construction etc. As per a strict measure used by the National Sample Survey in its 63rd round, called monthly per capita expenditure, rural expenditure accounts for 55% of total national monthly expenditure. The rural population currently accounts for one-third of the total Indian FMCG sales. [ 11 ]
In Japan, rural areas are referred to as "Inaka" which translates literally to "the countryside" or "one's native village". [ 12 ] [ 13 ]
According to the 2017 census about 64% of Pakistanis live in rural areas. Most rural areas in Pakistan tend to be near cities and are peri-urban areas. This is due to the definition of a rural area in Pakistan being an area that does not come within an urban boundary. [ 14 ] Rural areas in Pakistan that are near cities are considered as suburban areas or suburbs .
The remote rural villagers of Pakistan commonly live in houses made of bricks, clay or mud. Socioeconomic status among rural Pakistani villagers is often based upon the ownership of agricultural land , which also may provide social prestige in village cultures. The majority of rural Pakistani inhabitants livelihoods is based upon the rearing of livestock, which also comprises a significant part of Pakistan's gross domestic product. Some livestock raised by rural Pakistanis include cattle and goats.
In New Zealand census areas are classified based on their degree of rurality. However, traffic law has a different interpretation and defines a Rural area as " ... a road or a geographical area that is not an urban traffic area, to which the rural speed limit generally applies. " [ 15 ]
Rural economics is the study of rural economies . Rural economies include both agricultural and non-agricultural industries, so rural economics has broader concerns than agricultural economics which focus more on food systems . [ 16 ] Rural development [ 17 ] and finance [ 18 ] attempt to solve larger challenges within rural economics. These economic issues are often connected to the migration from rural areas due to lack of economic activities [ 19 ] and rural poverty . Some interventions have been very successful in some parts of the world, with rural electrification and rural tourism providing anchors for transforming economies in some rural areas. These challenges often create rural-urban income disparities. [ 20 ]
Rural development is the process of improving the quality of life and economic well-being of people living in rural areas, often relatively isolated and sparsely populated areas. [ 24 ] Often, rural regions have experienced rural poverty , poverty greater than urban or suburban economic regions due to lack of access to economic activities, and lack of investments in key infrastructure such as education.
Rural development has traditionally centered on the exploitation of land-intensive natural resources such as agriculture and forestry . However, changes in global production networks and increased urbanization have changed the character of rural areas. Increasingly rural tourism , niche manufacturers, and recreation have replaced resource extraction and agriculture as dominant economic drivers. [ 25 ] The need for rural communities to approach development from a wider perspective has created more focus on a broad range of development goals rather than merely creating incentive for agricultural or resource-based businesses.
Rural electrification is the process of bringing electrical power to rural and remote areas. Rural communities are suffering from colossal market failures as the national grids fall short of their demand for electricity. As of 2019, 770 million people live without access to electricity – 10.2% of the global population. [ 29 ] Electrification typically begins in cities and towns and gradually extends to rural areas, however, this process often runs into obstacles in developing nations. Expanding the national grid is expensive and countries consistently lack the capital to grow their current infrastructure. Additionally, amortizing capital costs to reduce the unit cost of each hook-up is harder to do in lightly populated areas (yielding higher per capita share of the expense). If countries are able to overcome these obstacles and reach nationwide electrification, rural communities will be able to reap considerable amounts of economic and social development.
Rural flight (also known as rural-to-urban migration, rural depopulation, or rural exodus) is the migratory pattern of people from rural areas into urban areas . It is urbanization seen from the rural perspective.
In industrializing economies like Britain in the eighteenth century or East Asia in the twentieth century , it can occur following the industrialization of primary industries such as agriculture , mining , fishing , and forestry —when fewer people are needed to bring the same amount of output to market—and related secondary industries (refining and processing) are consolidated. Rural exodus can also follow an ecological or human-caused catastrophe such as a famine or resource depletion. These are examples of push factors .
People can also move into town to seek higher wages , educational access and other urban amenities; examples of pull factors .
Once rural populations fall below a critical mass , the population is too small to support certain businesses, which then also leave or close, in a vicious circle . Services to smaller and more dispersed populations may be proportionately more expensive , which can lead to closures of offices and services, which further harm the rural economy. Schools are the archetypal example because they influence the decisions of parents of young children: a village or region without a school will typically lose families to larger towns that have one. But the concept ( urban hierarchy ) can be applied more generally to many services and is explained by central place theory .
Rural poverty refers to situations where people living in non-urban regions are in a state or condition of lacking the financial resources and essentials for living. It takes account of factors of rural society , rural economy , and political systems that give rise to the marginalization and economic
disadvantage found there. [ 32 ] Rural areas, because of their small, spread-out populations, typically have less well maintained infrastructure and a harder time accessing markets, which tend to be concentrated in population centers.
Rural communities also face disadvantages in terms of legal and social protections, with women and marginalized communities frequently having a harder time accessing land, education and other support systems that help with economic development. Several policies have been tested in both developing and developed economies, including rural electrification and access to other technologies such as internet, gender parity , and improved access to credit and income.
In academic studies, rural poverty is often discussed in conjunction with spatial inequality , which in this context refers to the inequality between urban and rural areas. [ 33 ] Both rural poverty and spatial inequality are global phenomena, but like poverty in general, there are higher rates of rural poverty in developing countries than in developed countries . [ 34 ]
Eradicating rural poverty through effective policies and economic growth is a continuing difficulty for the international community, as it invests in rural development . [ 34 ] [ 36 ] According to the International Fund for Agricultural Development , 70 percent of the people in extreme poverty are in rural areas, most of whom are smallholders or agricultural workers whose livelihoods are heavily dependent on agriculture. [ 37 ] These food systems are vulnerable to extreme weather, which is expected to affect agricultural systems the world over more as climate change increases . [ 38 ] [ 39 ]
In medicine , rural health or rural medicine is the interdisciplinary study of health and health care delivery in rural environments. The concept of rural health incorporates many fields, including wilderness medicine , geography , midwifery , nursing , sociology , economics , and telehealth or telemedicine . [ 42 ]
Rural populations often experience health disparities and greater barriers in access to healthcare compared to urban populations. [ 43 ] [ 44 ] Globally, rural populations face increased burdens of noncommunicable diseases such as cardiovascular disease, cancer, diabetes, and chronic obstructive pulmonary disorder, contributing to worse health outcomes and higher mortality rates. [ 45 ] Factors contributing to these health disparities include remote geography , increased rates of health risk behaviors, lower population density , decreased health insurance coverage among the population, lack of health infrastructure, and work force demographics. [ 44 ] [ 46 ] [ 47 ] People living in rural areas also tend to have less education, lower socioeconomic status , and higher rates of alcohol and smoking when compared to their urban counterparts. [ 48 ] Additionally, the rate of poverty is higher in rural populations globally, contributing to health disparities due to an inability to access healthy foods, healthcare, and housing. [ 49 ] [ 50 ]
Because of their unique dynamics, different academic fields have developed to study rural communities.
Rural economics is the study of rural economies . Rural economies include both agricultural and non-agricultural industries, so rural economics has broader concerns than agricultural economics which focus more on food systems . [ 53 ] Rural development [ 54 ] and finance [ 55 ] attempt to solve larger challenges within rural economics. These economic issues are often connected to the migration from rural areas due to lack of economic activities [ 56 ] and rural poverty . Some interventions have been very successful in some parts of the world, with rural electrification and rural tourism providing anchors for transforming economies in some rural areas. These challenges often create rural-urban income disparities. [ 57 ]
Rural planning is an academic discipline that exists within or alongside the field of urban planning , regional planning or urbanism . The definition of these fields differs between languages and contexts. Sometimes the terms are used interchangeably.
Specific interventions and solutions will depend entirely on the needs of each region in each country, but generally speaking, regional planning at the macro level will seek to: [ 61 ]
1800s: Martineau · Tocqueville · Marx · Spencer · Le Bon · Ward · Pareto · Tönnies · Veblen · Simmel · Durkheim · Addams · Mead · Weber · Du Bois · Mannheim · Elias
Rural sociology is a field of sociology traditionally associated with the study of social structure and conflict in rural areas. It is an active academic field in much of the world, originating in the United States in the 1910s with close ties to the national Department of Agriculture and land-grant university colleges of agriculture. [ 62 ] | https://en.wikipedia.org/wiki/Rural_area |
Rusavskia elegans (formerly Xanthoria elegans ), commonly known as the elegant sunburst lichen , [ 1 ] is a lichenized species of fungus in the genus Rusavskia , family Teloschistaceae . Recognized by its bright orange or red pigmentation, this species grows on rocks, often near bird or rodent perches. It has a circumpolar and alpine distribution. It was one of the first lichens to be used for the rock-face dating method known as lichenometry .
Rusavskia elegans was first formally described by Johann Heinrich Friedrich Link as Lichen elegans in 1791, [ 2 ] and transferred to the genus Xanthoria by Theodor Magnus Fries (son of Elias Magnus Fries ) in 1860. [ 3 ] In 2003, Sergey Kondratyuk and Ingvar Kärnefelt transferred the taxon to their newly circumscribed genus Rusavskia , in which it is the type species . [ 4 ] Although the new genus was not initially widely accepted, subsequent molecular phylogenetic studies showed the validity of the new classification. [ 5 ] [ 6 ] [ 7 ]
Its photosynbioant belongs to genus Trebouxia . [ 8 ]
The thallus of this lichen is described as foliose, having the aspect of leaves, although the central portions of the thallus may appear nearly crustose. It is small, typically less than 5 cm (2 in) wide, with lobes less than 2 mm (0.08 in) broad, appressed to loosely appressed. The upper surface is some shade of orange while the lower surface is white, corticate , with short, sparse hapters (an attachment structure produced by some lichens). The vegetative propagules called soredia and isidia are absent, although apothecia are common. [ 9 ] It has been described as possessing swollen, orange-yellow thalli (in streams), compact orange thalli (on boulders) or dark orange-red thalli on the driest rock faces. [ 10 ]
The variety R. elegans var. granulifera , characterized by having isidium-like vegetative propagules, has been reported from Greenland and Spitsbergen . [ 11 ]
R. elegans was one of the first species used for lichenometry , [ 12 ] a technique of estimating the age of rock faces by measuring the diameter of the lichen thalli growing on them. After an initial period of one or two decades to establish growth (the ecesis interval), R. elegans grows at a rate of 0.5 mm per year for the first century, before slowing somewhat. [ 13 ] [ 14 ]
This species grows on rock, both calcareous and siliceous , occasionally overgrowing moss or litter. It is often found on exposed to somewhat sheltered sites, often near bird or small-mammal droppings. [ 9 ] It has also adapted successfully to growth on man-made and natural growing surfaces from the sea-water spray zone to the boreal forest and in the grasslands of the continental interior. [ 15 ] [ 16 ] [ 17 ] It can thrive in areas having less than 6 centimetres (2.4 in) annual precipitation and can survive submerged in streams for much of the growing season. [ 10 ]
R. elegans has a broad circumpolar and alpine distribution, and is found on all continents except Australia . [ 18 ] It is widespread in Antarctic regions. [ 19 ]
The lichen is used as a model system to study the potential to resist extreme environments of outer space . Out of various lichens tested, it showed the ability to recover from space-simulating situations, including exposure to 16 hours of vacuum at 10 −3 Pa and UV radiation at wavelengths less than 160 nm or greater than 400 nm. [ 20 ] R. elegans has survived an 18-month exposure to solar UV radiation, cosmic rays, vacuum and varying temperatures in an experiment performed by the ESA outside of the ISS . [ 21 ]
Various anthraquinone compounds have been identified in R. elegans , including allacinal, physcion, teloschistin, [ 22 ] xanthorin, [ 23 ] and erythoglaucin, [ 24 ] murolic acid and a glycoside derivative of murolic acid ((18 R )-18- O -β- D -apiofuranosyl-(1-2)-β- D -glucopyranoside). [ 25 ] The algae symbiont produces a cyclopeptide, cyclo-( L -tryptophyl- L -tryptophyl). [ 8 ]
Carotenoids have a number of physiological functions in lichens, such as enhancing the availability of light energy for photosynthesis and protecting the organism from the photooxidizing action of UV light . [ 26 ] In R. elegans , as in many Rusavskia species, specimens growing in areas with intense UV radiation contain more carotenoids than those grown in more shaded areas. The biosynthesis of carotenoids is also dependent on the season of the year, as was shown in a study of R. elegans in Antarctica. [ 27 ] The predominant carotenoid in R. elegans , responsible for the orange-yellow color, is mutatoxanthin. [ 26 ] | https://en.wikipedia.org/wiki/Rusavskia_elegans |
In statistical mechanics , the Rushbrooke inequality relates the critical exponents of a magnetic system which exhibits a first-order phase transition in the thermodynamic limit for non-zero temperature T .
Since the Helmholtz free energy is extensive , the normalization to free energy per site is given as
The magnetization M per site in the thermodynamic limit , depending on the external magnetic field H and temperature T is given by
where σ i {\displaystyle \sigma _{i}} is the spin at the i-th site, and the magnetic susceptibility and specific heat at constant temperature and field are given by, respectively
and
Additionally,
The critical exponents α , α ′ , β , γ , γ ′ {\displaystyle \alpha ,\alpha ',\beta ,\gamma ,\gamma '} and δ {\displaystyle \delta } are defined in terms of the behaviour of the order parameters and response functions near the critical point as follows
where
measures the temperature relative to the critical point .
Using the magnetic analogue of the Maxwell relations for the response functions , the relation
follows, and with thermodynamic stability requiring that c H , c M and χ T ≥ 0 {\displaystyle c_{H},c_{M}{\mbox{ and }}\chi _{T}\geq 0} , one has
which, under the conditions H = 0 , t > 0 {\displaystyle H=0,t>0} and the definition of the critical exponents gives
which gives the Rushbrooke inequality [ 1 ]
Remarkably, in experiment and in exactly solved models, the inequality actually holds as an equality. | https://en.wikipedia.org/wiki/Rushbrooke_inequality |
The Rushton turbine or Rushton disc turbine is a radial flow impeller used for many mixing applications (commonly for gas dispersion applications) in process engineering and was invented by John Henry Rushton . [ 1 ] The design is based on a flat horizontal disk, with flat, vertically-mounted blades . [ 2 ] Recent innovations include the use of concave or semi-circular blades. [ 3 ]
This engineering-related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Rushton_turbine |
The Fritz J. and Dolores H. Russ Prize is an American national and international award established by the United States National Academy of Engineering (NAE) in October 1999 in Athens . Named after Fritz Russ, the founder of Systems Research Laboratories , and his wife Dolores Russ, it recognizes a bioengineering achievement that "has had a significant impact on society and has contributed to the advancement of the human condition through widespread use". The award was instigated at the request of Ohio University to honor Fritz Russ, one of its alumni. [ 1 ]
The first Russ Prize was awarded in 2001 to Earl E. Bakken and Wilson Greatbatch . The prize is awarded biennially in odd years. From 2003 to 2011, there was a single winner per award. Multiple winners were recognized starting in 2013. The first non-Americans to receive the Russ Prize were three of the five co-winners honored in 2015.
Only living persons may receive the prize, and recipients of the Charles Stark Draper Prize are not also eligible for the Russ Prize. [ 2 ] Members of the NAE and non-members worldwide are able to receive the award. [ 1 ] [ 3 ]
The winners are announced during National Engineers Week in February. They receive US$500,000, a gold medallion and a hand-scribed certificate. [ 1 ] The Russ Prize, the Gordon Prize and the Draper Prize , all awarded by the NAE, are known collectively as the " Nobel Prizes of Engineering ". [ 4 ] [ 5 ] [ 6 ] [ 7 ] | https://en.wikipedia.org/wiki/Russ_Prize |
Russell Marcus is a philosopher specializing in philosophy of mathematics and the pedagogy of philosophy. He is Chair of Philosophy at Hamilton College and president of the American Association of Philosophy Teachers . [ 1 ]
Prior to his work in philosophy, Marcus taught mathematics and other subjects at high schools in New York City and Costa Rica. [ 1 ] He received his bachelor of arts in philosophy at Swarthmore College in 1988. He received his doctorate from the Graduate Center of the City University of New York in 2007, [ 2 ] where he wrote his dissertation "Numbers without Science". [ 3 ] While at graduate school , he taught philosophy and mathematics at Queens College , Hofstra University and the College of Staten Island . [ 1 ] [ 2 ] He began teaching at Hamilton College in 2007, later setting up the Hamilton College Summer Program in Philosophy. [ 1 ] He gained tenure in 2016 and was appointed Chair of Philosophy in 2020. [ 2 ] [ 4 ] In 2020, he won the American Philosophical Association 's Prize for Excellence in Philosophy Teaching which "recognizes a philosophy teacher who has had a profound impact on the student learning of philosophy in undergraduate and/or pre-college settings", being cited as an "important scholar of teaching and learning in philosophy" for his summer program and "inventive team-based pedagogies and exemplary scaffolded assignments". [ 1 ] | https://en.wikipedia.org/wiki/Russell_Marcus |
Russell Stephen Drago (November 5, 1928 – December 5, 1997) was an American professor of inorganic chemistry . He mentored more than 130 PhD students, authored over a dozen textbooks and four hundred research documents, which have been published in several languages. [ citation needed ] He filed 17 process patents. [ 1 ]
Russell S. Drago was born November 5, 1928, in Montague, Massachusetts to Stephen R. Drago and Lillia Mary Margret (Pucci) Drago.
In 1950, Drago married Ruth Ann Burrill (January 29, 1929 – November 9, 2013). They remained married for 47 years until his death. They had four children, Patti Kouba (Drago), Steve, Paul, and Robert. [ 2 ]
In June, 1950, Drago graduated with a BS degree in chemistry from the University of Massachusetts Amherst . After he completed his time with the U.S. Air Force, he enrolled at Ohio State University under the GI bill , completing his Ph.D. degree on December 17, 1954, under Professor Harry Sisler. His thesis was entitled "Studies on the Synthesis of Chloramine and Hydrazine." [ 3 ] Subsequently he was a member of the chemistry faculty at the University of Illinois at Urbana–Champaign , where he remained until 1982. In 1966, he published the textbook Physical Methods in Inorganic Chemistry. [ 4 ] In 1982, he moved to the University of Florida .
Drago's initial independent research continued his PhD work. [ 5 ] Subsequently he expanded the scope to covered both the theoretical and practical side of acid-base chemistry. He developed the E and C equation as a quantitative model for acid-base reactions. [ 6 ] His group used a variety of physical methods to probe intermolecular interactions. He conducted NMR studies of paramagnetic complexes. [ 7 ] He contributed to the area of catalysis focusing primarily on chemical processes relevant to industrial applications. Work in this field contributed significantly to the understanding of ligand – metal and metal – metal interactions and their influence on the mechanisms, activity, and selectivity of numerous transition metals catalyzed systems.
A video interview with Drago is available. [ 8 ] | https://en.wikipedia.org/wiki/Russell_S._Drago |
The Russell Varian Prize was an international scientific prize awarded for a single, high-impact and innovative contribution in the field of nuclear magnetic resonance (NMR), that laid the foundation for the development of new technologies in the field. [ 1 ] It honored the memory of Russell Varian , the pioneer behind the creation of the first commercial NMR spectrometer and the co-founder, in 1948, of Varian Associates , one of the first high-tech companies in Silicon Valley . [ 2 ] The prize carried a monetary award of €15,000 and it was awarded annually between the years 2002 and 2015 (except for 2003) by a committee of experts in the field. [ 1 ] The award ceremony alternated between the European Magnetic Resonance (EUROMAR) Conference and the International Council on Magnetic Resonance in Biological Systems (ICMRBS) Conference. [ 1 ] Originally, the prize was sponsored by Varian, Inc. and later by Agilent Technologies , [ 3 ] after the latter acquired Varian, Inc. in 2010. [ 4 ] The prize was discontinued in 2016 after Agilent Technologies closed its NMR division. [ 5 ] | https://en.wikipedia.org/wiki/Russell_Varian_Prize |
The Russian Astronomical Society ( Russian : Русское астрономическое общество was a society established in Saint Petersburg , Russia in 1891 for the promotion of astronomy related studies. In 1894 the society also started publishing the scientific "Journal of the Russian Astronomical Society" ( Russian : Известия Русского астрономического общества )
In 1932 the Society was transformed into the Unional Astronomical and Geophysical Society .
This article about an organization or institute connected with astronomy is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Russian_Astronomical_Society |
The Engineer Troops of the Russian Federation ( Russian : Инженерные войска Российской Федерации ) are a Combat Arm and military administrative corps of the Russian Ground Forces of the Russian Federation designed to perform military engineering operations (combat actions), requiring special training of personnel and use of means of engineer equipment, as well as for damaging the enemy through application of engineer ammunition.
One of the first engineering units founded in the Russian Empire was the Pososhniye lyudi , a collective name for conscripts in the Imperial Russian Army called up for military service from each sokha unit . In the late 17th century, the first engineering training maneuvers were carried out under the patronage of Peter I . The day of the Engineering Forces is recognized as 21 January 1701, with on the opening of the School of the Pushkar Order. The first engineering schools were created in 1708 in Moscow and then in March 1719 in St. Petersburg. The terms of study at these schools ranged from 5 to 12 years. The Imperial Engineering Troops first took part in the Battle of Poltava , the Patriotic War of 1812 , Crimean War from 1853 to 1856, and the First World War. [ 1 ]
After the February Revolution and the Great October Socialist Revolution of 1917 the newly formed Red Army and Soviet Navy incorporated the sapper units of the former Imperial Russian Army and Navy in their structure. By 1919, pontoon and electrical battalions and a mine-blasting brigade were raised in time for the Civil War. 10 years later, the Engineering Troops of the USSR ( Russian : Инженерные войска СССР ) were in much better shape and had a much better organization. During the Second World War, ten sapper armies operated, later reorganized into brigades. From the mid-1940s to the 1970s, Engineer-Sapper Companies (ISR) were located in Soviet Army regiments, divisions, and combined-arms armies. Due to miscalculations in planning by the Ministry of Defense of the Soviet Union , there was a shortage of engineering units serving in Afghanistan during the Soviet–Afghan War . In 1986, the Engineering Troops took part in the military response to the biological effects of the Chernobyl accident . After the collapse of the USSR in late 1991, the engineering troops were dissolved and its component units were absorbed by Russia and the newly formed armed forces of nations such as Ukraine , Belarus , Kazakhstan , and Armenia . [ 2 ]
The official holiday of the Engineering Troops was established by decree of President Boris Yeltsin on 18 September 1996. By order of the Minister of Defense on 23 September 1996, it was prescribed to celebrate the Day of Engineering Troops on January 21 annually. [ 3 ]
In preparation and conduct of combined-arms operations (combat actions) the Engineer Troops perform, among others, the following tasks:
In addition, they are involved in countering the intelligence systems and homing of the enemy's weapons ( camouflage ), simulation of troops and facilities, providing misinformation and demonstrative actions to deceive the enemy as well as to eliminate or reduce the effects of enemy weapons of mass destruction.
In peacetime, the Engineer Troops have a number of important and socially significant tasks: they clean areas of explosive hazards, are involved in the response and liquidation of aftermath of man-made accidents and catastrophes, natural disasters, prevent destruction of bridges and waterworks during floating of ice, etc. Further development of the Engineer Troops is carried out through equipping them with qualitatively new, highly effective, versatile means of engineer equipment, built on the basis of standardised elements, blocks and modules, with a simultaneous decrease of the nomenclature samples of the same type for the intended purpose. [ 4 ]
The Engineer Troops are composed of formations, units and subdivisions for various purposes: engineering-reconnaissance, field engineering, fencing, obstacle clearing, assault-and-traffic engineering, pontoon bridge (pontoon), assault-crossing, camouflage-engineering, technology-engineering, field water supplying ones and so on.
This article incorporates text by Ministry of Defence of the Russian Federation available under the CC BY 4.0 license.
Media related to Engineer Troops of the Russian Armed Forces at Wikimedia Commons | https://en.wikipedia.org/wiki/Russian_Engineer_Troops |
The Russian Journal of Physical Chemistry A: Focus on Chemistry ( Russian : Журнал физической химии , romanized : Zhurnal fizicheskoi khimii ) [ 1 ] is an English-language translation of the eponymous Russian-language peer-reviewed scientific journal published by Springer Science+Business Media on behalf of Pleiades Publishing. It was established in 1930 and focuses on review articles pertaining to global coverage of all theory and experiment in physical chemistry . The editor-in-chief is Aslan Yu. Tsivadze ( Russian Academy of Sciences ).
The journal is abstracted and indexed in:
According to the Journal Citation Reports , the journal has a 2022 impact factor of 0.7. [ 7 ]
This article about a physical chemistry journal is a stub . You can help Wikipedia by expanding it .
See tips for writing articles about academic journals . Further suggestions might be found on the article's talk page . | https://en.wikipedia.org/wiki/Russian_Journal_of_Physical_Chemistry_A |
The Russian Journal of Physical Chemistry B ( Russian : Химическая физика , romanized : Khimicheskaya fizika ) [ 1 ] is an English-language translation of the eponymous Russian-language peer-reviewed scientific journal published by MAIK Nauka /Interperiodica and Springer Science+Business Media . The journal covers all aspects of chemical physics and combustion . The editor-in-chief is Anatoly L. Buchachenko ( Russian Academy of Sciences ).
This article about a physical chemistry journal is a stub . You can help Wikipedia by expanding it .
See tips for writing articles about academic journals . Further suggestions might be found on the article's talk page . | https://en.wikipedia.org/wiki/Russian_Journal_of_Physical_Chemistry_B |
Russian tsunami warning system ( Russian : Российская система предупреждения о цунами ), also known as Russian tsunami warning service ( Russian : Российская служба предупреждения о цунами ), is a tsunami warning system in the Russian Far East which is operated and maintained by the Geophysical Service of the Russian Academy of Sciences together with the Far Eastern Regional Research Hydrometeorological Institute ( Russian : Дальневосточный региональный научно-исследовательский гидрометеорологический институт (ДВНИГМИ) ). It is subordinated to the Federal Service for Hydrometeorology and Environmental Monitoring . The Russian tsunami warning system is known under the Russian acronym FP RSCHS-Tsunami ( Russian : ФП РСЧС-Цунами ). [ 1 ]
The Russian tsunami warning system development began in 1956 to 1959. [ 2 ] This followed the tsunami and damage which occurred during the 1952 Severo-Kurilsk earthquake . After this, a government decree was issued for the organization of a tsunami warning service. Since 1956, the seismic part of the work was carried out by the Yuzhno-Sakhalinsk seismic station.
In 2003, following the creation of the Unified State System for the Prevention and Elimination of Emergency Situations (RSChS; ( Russian : РСЧС ), the tsunami warning service received the status of a functional subsystem of the unified system with the acronym FP RSChS-Tsunami ( Russian : ФП РСЧС-Цунами ).
In the second half of 2000, the system began a modernization process which included the deployment of new buoys . [ 3 ]
The Russian tsunami warning system includes a network of seismological stations, a hydrophysical (level) network, tsunami warning centers, and a communication system for tsunami warnings. System components are located in Sovetskaya Gavan , Nevelsk , Rudnaya Pristan , Vladivostok , Nakhodka , Preobrazhenye , Uglegorsk , Poronaysk , Starodubskoye , Kholmsk , Korsakov , Cape Crillon , Yuzhno Kurilsk and Vodopadnaya . [ 4 ]
rtws .ru - Russian tsunami warning system | https://en.wikipedia.org/wiki/Russian_Tsunami_Warning_System |
The Russian Union of Engineers (RUE) (Russian: Российский союз инженеров (РСИ)) claims to be an all-Russian nongovernmental organization of engineers , design-engineers, builders , inventors , rationalizers, researchers , scientists , scientific and technical employees, and managers of industrial production . It has published several studies on economics, energy and housing related subjects and a paper on Malaysia Airlines Flight 17 .
On January 21, 2012, at the Polytechnical Museum of Moscow, the Russian Union of Engineers presented the general rating of city appeal of Russian cities [ 1 ] for 2011.
On May 20, 2013, the Ministry of Regional Development of the Russian Federation, the Federal Agency of Construction and Housing of the Russian Federation, Russian Union of Engineers and the experts of Lomonosov Moscow State University developed a rating and methodology of evaluation of urban environment and analyzed the 50 largest Russian cities . [ 2 ] [ 3 ] [ 4 ] For this work, the Union designed the methods of urban environment quality assessment and a city appeal threshold.
The rating has been developed: | https://en.wikipedia.org/wiki/Russian_Union_of_Engineers |
The Russian tortoise ( Testudo horsfieldii ) , also commonly known as the Afghan tortoise , the Central Asian tortoise , the four-clawed tortoise , the four-toed tortoise , Horsfield's tortoise , the Russian steppe tortoise , the Soviet Tortoise , and the steppe tortoise , [ 3 ] [ 4 ] is a threatened species of tortoise in the family Testudinidae . The species is endemic to Central Asia from the Caspian Sea south through Iran, Pakistan and Afghanistan, and east across Kazakhstan to Xinjiang, China. [ 5 ] [ 6 ] Human activities in its native habitat contribute to its threatened status. [ 5 ]
Two Russian tortoises were the first Earth inhabitants to travel to and circle the Moon, on Zond 5 in September 1968.
Both the specific name , horsfieldii , and the common name "Horsfield's tortoise" are in honor of the American naturalist Thomas Horsfield . He worked in Java (1796) and for the East India Company and later became a friend of Sir Thomas Raffies. [ 7 ] [ 3 ]
This species is traditionally placed in Testudo . Due to distinctly different morphological characteristics, the monotypic genus Agrionemys was proposed for it in 1966, and was accepted for several decades, although not unanimously. [ 5 ] [ 8 ] [ full citation needed ] DNA sequence analysis generally concurred, but not too robustly so. [ 9 ] [ full citation needed ] However, in 2021, it was again reclassified in Testudo by the Turtle Taxonomy Working Group and the Reptile Database , with Agrionemys being relegated to a distinct subgenus that T. horsfieldii belonged to. [ 5 ] [ 10 ] The Turtle Taxonomy Working Group lists five separate subspecies of Russian tortoise, but they are not widely accepted by taxonomists : [ 5 ]
The Russian tortoise is a small tortoise species, with a size range of 13–25 cm (5–10 in). Females grow slightly larger (15–25 cm [6–10 in]) to accommodate eggs. Males average 13–20 cm (5–8 in).
Russian tortoises are sexually dimorphic . Males are usually smaller than the females, [ 11 ] and the males tend to have longer tails generally tucked to the side, and longer claws; females have a short, fat tail, with shorter claws than the males. The male has a slit-shaped vent ( cloaca ) near the tip of its tail; the female has an asterisk-shaped vent (cloaca). Russian tortoises have four toes on their front limbs, unusual compared to other tortoises for having five. Coloration varies, but the shell is usually a ruddy brown or black, fading to yellow between the scutes, and the body is straw-yellow and brown depending on the subspecies.
The male Russian tortoise courts a female through head bobbing, circling, and biting her forelegs. When she submits, he mounts her from behind, making high-pitched squeaking noises during mating. [ 12 ]
On average, Russian tortoises will hibernate for about 8 weeks to 5 months throughout the year, if the conditions are right. [ 13 ] The species can spend as much as 9 months of the year in dormancy.
Russian tortoises thrive in dry, open areas. They keep to sandy locations, where they can get around easily and burrow. Despite preferring arid environments primarily, Russian tortoises can survive well where humidity is 70 percent, and actually need some rain to soften the soil so they can dig their burrows. [ 14 ] These burrows can be as deep as 2 meters (6 ft 7 in), where it retreats during the midday heat and at night, only emerging to forage at dawn or dusk when temperatures drop. These tortoises are quite social, and they will visit nearby burrows, and sometimes several will spend the night in one burrow. [ 5 ]
Russian tortoises are popular pets. While they are a hardy species, they do have some specific needs. Russian tortoises requires a very dry, well-drained cage in an indoor enclosure. [ 15 ] They can be kept indoors or outdoors, but outdoor tortoise enclosures generally require less equipment and upkeep, and are preferable if the keeper lives in an appropriate climate. Indoor enclosures should measure 8'L x 4'W x 2.5'H (2.44 m × 1.22 m × 0.76 m), or otherwise offer 32 square feet (3.0 m 2 ) of floor space. Indoors, specialized equipment is required to maintain moderate temperatures and moderate humidity, with UVB light available in an appropriate strength.
In captivity, Russian tortoises' diet typically consists of lamb's lettuce , plantains and various other dark leafy greens. The Russian tortoise's natural diet consists of herbaceous and succulent vegetation including grasses, twigs, flowers and some fruits. [ 14 ] The diet should be as varied as possible to reduce the risk of imbalanced nutrition. Water is important for all species; the tortoise, being an arid species, will typically get water from their food, but they still need a constant supply. Young Russian tortoises should be soaked 1-2x/weekly in lukewarm water no deeper than their elbows to keep hydrated. Tortoises typically empty their bowels in water to hide their scent; this is an instinct, and it also helps keep their enclosure cleaner. [ 16 ]
Russian tortoises can live up to 50 years, and require annual hibernation. [ citation needed ]
Russian tortoises do not require a CITES Article X certificate.
In September 1968 two Russian tortoises flew to the Moon, circled it, and returned safely to Earth on the Soviet Zond 5 mission. Accompanied by mealworms, plants, and other lifeforms, they were the first Earth creatures to travel to the Moon. [ 17 ] | https://en.wikipedia.org/wiki/Russian_tortoise |
The Russia–Ukraine barrier , also known as the Ukrainian Wall or the European Wall [ 2 ] [ 3 ] ( Ukrainian : Європейський вал , romanized : Yevropeiskyi val ), and officially called " Project Wall " ( Ukrainian : Проєкт «Стіна» , romanized : Proiekt "Stina" ) in Ukraine , [ 4 ] is a fortified border barrier built on the Ukrainian side of the Russia–Ukraine border . [ 1 ] Early construction began following the outbreak of the Russo-Ukrainian War in 2014, as the Ukrainian government sought to prevent any further incursions by Russia into Ukrainian territory following the Russian annexation of Crimea and the Russian-backed separatist uprising in the Donbas . [ 5 ] [ better source needed ] It was also aimed at helping Ukraine's position with obtaining visa-free travel to the European Union (see Ukraine–European Union relations ). [ 6 ] Former Ukrainian prime minister Arseniy Yatsenyuk presented this project on 3 September 2014, and it started officially in 2015. In June 2020, Ukraine's State Border Guard Service expected that the project would be finished by 2025. However, in a message to Focus in January 2022, they stated that the project had been completed at a cost of ₴2.5 billion. [ 7 ]
On 24 February 2022, all remaining construction on the barrier was suspended due to the Russian invasion of Ukraine .
Following the 2014 Russian military intervention in Ukraine , in June 2014, Ukrainian politician and business magnate Ihor Kolomoyskyi suggested that Ukraine should build a wall along the border with Russia. [ 8 ] On 3 September 2014, Ukrainian Prime Minister Arseniy Yatsenyuk announced Ukraine would strengthen its border with Russia and called this "Project Wall". [ 9 ] The command of Ukraine's anti-terrorist forces stated that "Two defense lines have been planned, and their main goal is to prevent the infiltration by the adversary into the territory of Ukraine". [ 10 ] According to Yatsenyuk the project was needed "to cut off Russian support for insurgents in eastern regions " and also to obtain a visa-free regime with the European Union for Ukraine. [ 11 ] [ 12 ] It is also an employment project. [ 13 ] Project "Wall" was officially started on 10 September 2014. [ 14 ]
On September 12, 2014, The Cabinet of Ministers of Ukraine allocated 100 million hryvnia [ 15 ] for the construction of fortifications on the border with Russia and on the border with Crimea . On 18 March 2015, the Ukrainian government allocated 865 million hryvnia to build fortifications on the border between Ukraine and Russia. [ 16 ] On 10 April 2015, Poland allocated a loan of $100 million for the modernization of the energy sector and improvement of external borders of Ukraine .
As of May 2015, a walled defense system was under construction along the Russian border in Kharkiv Oblast . [ 17 ] The project was planned to be finished in 2018. [ 18 ]
On 20 August 2015, it was announced that Ukraine has completed 10% of the fortification line, stating that roughly 180 km of anti-tank ditches had been dug, 40 km of barbed wire fence and 500 fortification obstacles had been erected. 139 million hryvnia out of 300 million allocated has been used for construction of the wall at this point, and that another 460 million hryvnia were budgeted for 2016. [ 3 ] [ 19 ]
In August 2017, it became public that large amounts of the money intended to pay for the Wall project were misused and even stolen. The National Anti-Corruption Bureau (NABU) announced the arrest of several individuals involved in the building of the fortified border. [ 20 ]
On 5 June 2020, the State Border Guard Service of Ukraine stated that the Wall project was 40% implemented as of the end of May 2020. [ 1 ] Since 2015, $63.6 million has been spent on the project which the Border Guard Service expected to be finished by 2025. [ 1 ]
Head of the State Border Guard Service of Ukraine Serhii Deineko stated on 5 May 2021 that Ukraine had built 400 km of anti-tank trench, 100 km of fence and 70 km of barbed wire as part of "Project Wall". [ 21 ] According to him, border guards were completing work on the border in Kharkiv Oblast, part of the work was performed in Chernihiv Oblast , one site was completed in Luhansk Oblast , and in Sumy Oblast so far only design and survey works were underway. [ 21 ]
On 24 February 2022, the construction of the barrier was temporarily stopped when Russia invaded Ukraine . [ citation needed ] | https://en.wikipedia.org/wiki/Russia–Ukraine_barrier |
Rust is an iron oxide , a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture . Rust consists of hydrous iron(III) oxides (Fe 2 O 3 ·nH 2 O) and iron(III) oxide-hydroxide (FeO(OH), Fe(OH) 3 ), and is typically associated with the corrosion of refined iron .
Given sufficient time, any iron mass, in the presence of water and oxygen, could eventually convert entirely to rust. Surface rust is commonly flaky and friable , and provides no passivational protection to the underlying iron unlike other metals such as aluminum, copper , and tin which form stable oxide layers. Rusting is the common term for corrosion of elemental iron and its alloys such as steel . Many other metals undergo similar corrosion, but the resulting oxides are not commonly called "rust". [ 1 ]
Several forms of rust are distinguishable both visually and by spectroscopy , and form under different circumstances. [ 2 ] Other forms of rust include the result of reactions between iron and chloride in an environment deprived of oxygen. Rebar used in underwater concrete pillars , which generates green rust , is an example. Although rusting is generally a negative aspect of iron, a particular form of rusting, known as stable rust , causes the object to have a thin coating of rust over the top; this results from reaction with atmospheric oxygen. If kept free of moisture, it makes the "stable" layer protective to the iron below, but not to the extent of other oxides such as aluminium oxide on aluminium . [ 3 ]
Rust is a general name for a complex of oxides and hydroxides of iron, [ 4 ] which occur when iron or some alloys that contain iron are exposed to oxygen and moisture for a long period of time. Over time, the oxygen combines with the metal, forming new compounds collectively called rust, in a process called rusting. Rusting is an oxidation reaction specifically occurring with iron. Other metals also corrode via similar oxidation, but such corrosion is not called rusting.
The main catalyst for the rusting process is water. Iron or steel structures might appear to be solid, but water molecules can penetrate the microscopic pits and cracks in any exposed metal. The hydrogen atoms present in water molecules can combine with other elements to form acids, which will eventually cause more metal to be exposed. If chloride ions are present, as is the case with saltwater, the corrosion is likely to occur more quickly. Meanwhile, the oxygen atoms combine with metallic atoms to form the destructive oxide compound. These iron compounds are brittle and crumbly and replace strong metallic iron, reducing the strength of the object.
When iron is in contact with water and oxygen, it rusts. [ 5 ] If salt is present, for example in seawater or salt spray , the iron tends to rust more quickly, as a result of chemical reactions. Iron metal is relatively unaffected by pure water or by dry oxygen. As with other metals, like aluminium, a tightly adhering oxide coating, a passivation layer , protects the bulk iron from further oxidation. The conversion of the passivating ferrous oxide layer to rust results from the combined action of two agents, usually oxygen and water.
Other degrading solutions are sulfur dioxide in water and carbon dioxide in water. Under these corrosive conditions, iron hydroxide species are formed. Unlike ferrous oxides, the hydroxides do not adhere to the bulk metal. As they form and flake off from the surface, fresh iron is exposed, and the corrosion process continues until either all of the iron is consumed or all of the oxygen, water, carbon dioxide or sulfur dioxide in the system are removed or consumed. [ 6 ]
When iron rusts, the oxides take up more volume than the original metal; this expansion can generate enormous forces, damaging structures made with iron. See economic effect for more details.
The rusting of iron is an electrochemical process that begins with the transfer of electrons from iron to oxygen. [ 7 ] The iron is the reducing agent (gives up electrons) while the oxygen is the oxidizing agent (gains electrons). The rate of corrosion is affected by water and accelerated by electrolytes , as illustrated by the effects of road salt on the corrosion of automobiles. The key reaction is the reduction of oxygen:
Because it forms hydroxide ions , this process is strongly affected by the presence of acid. Likewise, the corrosion of most metals by oxygen is accelerated at low pH . Providing the electrons for the above reaction is the oxidation of iron that may be described as follows:
The following redox reaction also occurs in the presence of water and is crucial to the formation of rust:
In addition, the following multistep acid–base reactions affect the course of rust formation:
as do the following dehydration equilibria:
From the above equations, it is also seen that the corrosion products are dictated by the availability of water and oxygen. With limited dissolved oxygen, iron(II)-containing materials are favoured, including FeO and black lodestone or magnetite (Fe 3 O 4 ). High oxygen concentrations favour ferric materials with the nominal formulae Fe(OH) 3− x O x ⁄ 2 . The nature of rust changes with time, reflecting the slow rates of the reactions of solids. [ 5 ]
Furthermore, these complex processes are affected by the presence of other ions, such as Ca 2+ , which serve as electrolytes which accelerate rust formation, or combine with the hydroxides and oxides of iron to precipitate a variety of Ca, Fe, O, OH species.
The onset of rusting can also be detected in the laboratory with the use of ferroxyl indicator solution . The solution detects both Fe 2+ ions and hydroxyl ions. Formation of Fe 2+ ions and hydroxyl ions are indicated by blue and pink patches respectively.
Because of the widespread use and importance of iron and steel products, the prevention or slowing of rust is the basis of major economic activities in a number of specialized technologies. A brief overview of methods is presented here; for detailed coverage, see the cross-referenced articles.
Rust is permeable to air and water, therefore the interior metallic iron beneath a rust layer continues to corrode. Rust prevention thus requires coatings that preclude rust formation.
Stainless steel forms a passivation layer of chromium(III) oxide . [ 8 ] [ 9 ] Similar passivation behavior occurs with magnesium , titanium , zinc , zinc oxides , aluminium , polyaniline , and other electroactive conductive polymers. [ 10 ]
Special " weathering steel " alloys such as Cor-Ten rust at a much slower rate than normal, because the rust adheres to the surface of the metal in a protective layer. Designs using this material must include measures that avoid worst-case exposures since the material still continues to rust slowly even under near-ideal conditions. [ 11 ]
Galvanization consists of an application on the object to be protected of a layer of metallic zinc by either hot-dip galvanizing or electroplating . Zinc is traditionally used because it is cheap, adheres well to steel, and provides cathodic protection to the steel surface in case of damage of the zinc layer. In more corrosive environments (such as salt water), cadmium plating is preferred instead of the underlying protected metal. The protective zinc layer is consumed by this action, and thus galvanization provides protection only for a limited period of time.
More modern coatings add aluminium to the coating as zinc-alume ; aluminium will migrate to cover scratches and thus provide protection for a longer period. These approaches rely on the aluminium and zinc oxides protecting a once-scratched surface, rather than oxidizing as a sacrificial anode as in traditional galvanized coatings. In some cases, such as very aggressive environments or long design life, both zinc and a coating are applied to provide enhanced corrosion protection.
Typical galvanization of steel products that are to be subjected to normal day-to-day weathering in an outside environment consists of a hot-dipped 85 μm zinc coating. Under normal weather conditions, this will deteriorate at a rate of 1 μm per year, giving approximately 85 years of protection. [ 12 ]
Cathodic protection is a technique used to inhibit corrosion on buried or immersed structures by supplying an electrical charge that suppresses the electrochemical reaction. If correctly applied, corrosion can be stopped completely. In its simplest form, it is achieved by attaching a sacrificial anode, thereby making the iron or steel the cathode in the cell formed. The sacrificial anode must be made from something with a more negative electrode potential than the iron or steel, commonly zinc, aluminium, or magnesium. The sacrificial anode will eventually corrode away, ceasing its protective action unless it is replaced in a timely manner.
Cathodic protection can also be provided by using an applied electrical current. This would then be known as ICCP Impressed Current Cathodic Protection. [ 13 ]
Rust formation can be controlled with coatings, such as paint , lacquer , varnish , or wax tapes [ 14 ] that isolate the iron from the environment. [ 15 ] Large structures with enclosed box sections, such as ships and modern automobiles, often have a wax-based product (technically a "slushing oil") injected into these sections. Such treatments usually also contain rust inhibitors. Covering steel with concrete can provide some protection to steel because of the alkaline pH environment at the steel–concrete interface. However, rusting of steel in concrete can still be a problem, as expanding rust can fracture concrete from within. [ 16 ] [ 17 ]
As a closely related example, iron clamps were used to join marble blocks during a restoration attempt of the Parthenon in Athens, Greece , in 1898, but caused extensive damage to the marble by the rusting and swelling of unprotected iron. The ancient Greek builders had used a similar fastening system for the marble blocks during construction, however, they also poured molten lead over the iron joints for protection from seismic shocks as well as from corrosion. This method was successful for the 2500-year-old structure, but in less than a century the crude repairs were in imminent danger of collapse. [ 18 ] When only temporary protection is needed for storage or transport, a thin layer of oil, grease or a special mixture such as Cosmoline can be applied to an iron surface. Such treatments are extensively used when " mothballing " a steel ship, automobile, or other equipment for long-term storage.
Special anti-seize lubricant mixtures are available and are applied to metallic threads and other precision machined surfaces to protect them from rust. These compounds usually contain grease mixed with copper, zinc, or aluminium powder, and other proprietary ingredients. [ 19 ]
Bluing is a technique that can provide limited [ citation needed ] resistance to rusting for small steel items, such as firearms; for it to be successful, a water-displacing oil is rubbed onto the blued steel and other steel. [ citation needed ]
Corrosion inhibitors, such as gas-phase or volatile inhibitors, can be used to prevent corrosion inside sealed systems. They are not effective when air circulation disperses them, and brings in fresh oxygen and moisture.
Rust can be avoided by controlling the moisture in the atmosphere. [ 20 ] An example of this is the use of silica gel packets to control humidity in equipment shipped by sea.
Rust removal from small iron or steel objects by electrolysis can be done in a home workshop using simple materials such as a plastic bucket filled with an electrolyte consisting of washing soda dissolved in tap water , a length of rebar suspended vertically in the solution to act as an anode , another laid across the top of the bucket to act as a support for suspending the object, baling wire to suspend the object in the solution from the horizontal rebar, and a battery charger as a power source in which the positive terminal is clamped to the anode and the negative terminal is clamped to the object to be treated which becomes the cathode . [ 21 ] Hydrogen and oxygen gases are produced at the cathode and anode respectively. This mixture is flammable/explosive. [ 22 ] Care should also be taken to avoid hydrogen embrittlement . Overvoltage also produces small amounts of ozone, which is highly toxic, so a low voltage phone charger is a far safer source of DC current. The effects of hydrogen on global warming have also recently come under scrutiny. [ 23 ]
Rust may be treated with commercial products known as rust converter which contain tannic acid or phosphoric acid which combines with rust; removed with organic acids like citric acid and vinegar or the stronger hydrochloric acid ; or removed with chelating agents as in some commercial formulations or even a solution of molasses . [ 24 ]
Rust is associated with the degradation of iron-based tools and structures. As rust has a much higher volume than the originating mass of iron, its buildup can also cause failure by forcing apart adjacent parts — a phenomenon sometimes known as "rust packing". It was the cause of the collapse of the Mianus river bridge in 1983, when the bearings rusted internally and pushed one corner of the road slab off its support.
Rust was an important factor in the Silver Bridge disaster of 1967 in West Virginia , when a steel suspension bridge collapsed in less than a minute, killing 46 drivers and passengers on the bridge at the time. The Kinzua Bridge in Pennsylvania was blown down by a tornado in 2003, largely because the central base bolts holding the structure to the ground had rusted away, leaving the bridge anchored by gravity alone.
Reinforced concrete is also vulnerable to rust damage. Internal pressure caused by expanding corrosion of concrete-covered steel and iron can cause the concrete to spall , creating severe structural problems. It is one of the most common failure modes of reinforced concrete bridges and buildings.
Rust is a commonly used metaphor for slow decay due to neglect, since it gradually converts robust iron and steel metal into a soft crumbling powder. A wide section of the industrialized American Midwest and American Northeast , once dominated by steel foundries , the automotive industry , and other manufacturers, has experienced harsh economic cutbacks that have caused the region to be dubbed the " Rust Belt ".
In music, literature, and art, rust is associated with images of faded glory, neglect, decay, and ruin. | https://en.wikipedia.org/wiki/Rust |
Rust converters are chemical solutions or primers that can be applied directly to an iron or iron alloy surface to convert iron oxides ( rust ) into a protective chemical barrier. These compounds interact with iron oxides, especially iron(III) oxide , converting them into an adherent black layer ( black oxide ) that is more resistant to moisture and protects the surface from further corrosion . They are sometimes referred to as "rust remover" or "rust killer".
Commercial rust converters are water-based and contain two primary active ingredients: tannic acid [ 1 ] and an organic polymer . Tannic acid chemically converts the reddish iron oxides into bluish-black ferric tannate, a more stable material. [ 2 ] The second active ingredient is an organic solvent such as 2-butoxyethanol (ethylene glycol monobutyl ether, trade name butyl cellosolve) that acts as a wetting agent and provides a protective primer layer in conjunction with an organic polymer emulsion. [ citation needed ]
Some rust converters may contain additional acids to speed up the chemical reaction by lowering the pH of the solution. A common example is phosphoric acid , which additionally converts some iron oxide into an inert layer of ferric phosphate . [ 3 ] Most of the rust converters contain special additives. [ 4 ] They support the rust transformation and improve the wetting of the surface.
Rust converter is usually applied to objects that are difficult to sand blast , such as vehicles, trailers, fences, iron railings, sheet metal, and the outside of storage tanks. It may also be used to restore and preserve iron-based items of historical importance. [ 5 ] | https://en.wikipedia.org/wiki/Rust_converter |
A rusticle is a formation of rust similar to an icicle or stalactite in appearance that occurs deep underwater when iron-loving bacteria attack and oxidize wrought iron and steel . They may be familiar from underwater photographs of shipwrecks , such as the RMS Titanic and the German battleship Bismarck . They have also been found in the #3 turret, an 8-inch gun turret on the stern remains in place of the USS Indianapolis . [ 1 ] The word rusticle is a portmanteau of the words rust and icicle and was coined by Robert Ballard , who first observed them on the wreck of the Titanic in 1986. [ 2 ] Rusticles on the Titanic were first investigated in 1996 by Roy Cullimore, based at the University of Regina in Canada . A previously unknown species of bacteria living inside the Titanic ' s rusticles called Halomonas titanicae was discovered in 2010 by Henrietta Mann. [ 3 ]
Rusticles can form on any submerged steel object and have been seen on other subsea structures such as mooring chains [ 4 ] and subsea equipment. They form more rapidly in warmer climates and can form in water with little to no dissolved oxygen . [ 4 ]
The rusticle consists of up to 35% iron compounds including iron oxides , iron carbonates , and iron hydroxides . Rusticles are found in a tube shapes of iron oxides which are vertical to one another. Rusticles are found to grow at approximately 1 cm (0.39 in) a year and are most often found in areas of sunken hulls underwater.
The remainder of the structure is a complex community of symbiotic or mutualistic microbes including bacteria Halomonas titanicae and fungi that use the rusting metal as a source of food, causing microbial corrosion and collectively producing the mineral compounds that form the rusticle as waste products.
Rusticles have been found to most often be composed of iron, calcium, chloride, magnesium, silica, sodium, and sulfate while there are other chemical compositions of rusticles but in much smaller quantities. [ 5 ]
Structurally, rusticles contain channels which allow water to flow through, and they seem to build up in a ring structure similar to the growth rings of a tree . They are very delicate and can easily disintegrate into fine powder on even the slightest touch.
The outer surface of a rusticle is smooth red in appearance from the iron(III) oxide , while the core is bright orange due to the presence of crystals of goethite . There are several morphologies of the rusticle, some of which are conical, cylindrical, and rusticle on the seafloor.
This corrosion -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Rusticle |
Rustproofing is the prevention or delay of rusting of iron and steel objects, or the permanent protection against corrosion . Typically, the protection is achieved by a process of surface finishing or treatment. Depending on mechanical wear or environmental conditions, the degradation may not be stopped completely, unless the process is periodically repeated. [ not verified in body ] The term is particularly used in the automobile industry . [ citation needed ]
In the factory, car bodies are protected with special chemical formulations.
Typically [ according to whom? ] , phosphate conversion coatings were used. [ when? ] [ by whom? ] Some firms galvanized part or all of their car bodies before the primer coat of paint was applied. [ citation needed ] If a car is body-on-frame , then the frame (chassis) must also be rustproofed. In traditional automotive manufacturing of the early- and mid-20th century, paint was the final part of the rustproofing barrier between the body shell and the atmosphere, except on the underside. On the underside, an underseal rubberized or PVC -based coating was often sprayed on. [ when? ] These products will be breached eventually and can lead to unseen corrosion that spreads underneath the underseal. Old 1960s and 1970s rubberized underseal can become brittle on older cars and is particularly liable to this. [ citation needed ]
The first electrodeposition primer was developed in the 1950s, but were found to be impractical for widespread use. Revised cathodic automotive electrocoat primer systems were introduced in the 1970s that markedly reduced the problem of corrosion that had been experienced by a vast number of automobiles in the first seven decades of automobile manufacturing. Termed e-coat , "electrocoat automotive primers are applied by totally submerging the assembled car body in a large tank that contains the waterborne e-coat, and the coating is applied through cathodic electrodeposition. This assures nearly 100% coverage of all metal surfaces by the primer. The coating chemistry is waterborne enamel based on epoxy , an aminoalcohol adduct , and blocked isocyanate , which all crosslink on baking to form an epoxy-urethane resin system. [ 1 ]
E-coat resin technology, combined with the excellent coverage provided by electrodeposition, provides one of the more effective coatings for protecting steel from corrosion. For modern automobile manufacturing after the 1990s, nearly all cars use e-coat technology as base foundation for their corrosion protection coating system. [ 1 ]
Aftermarket kits are available to apply rustproofing compounds both to external surfaces and inside enclosed sections, for example sills/rocker panels (see monocoque ), through either existing or specially drilled holes. The compounds are usually wax-based and can be applied by aerosol can, brush, low pressure pump up spray, or compressor fed spray gun.
An alternative for sills/rocker panels is to block drain holes and simply fill them up with wax and then drain most of it out (the excess can be stored and reused), leaving a complete coating inside. Anti-rust wax like phosphoric acid based rust killers/neutralizers can also be painted on already rusted areas. Loose or thick rust must be removed before anti-rust wax like Waxoyl or a similar product is used. [ original research? ]
Structural rust (affecting structural components which must withstand considerable forces) should be cut back to sound metal and new metal welded in, or the affected part should be completely replaced. Wax may not penetrate spot-welded seams or thick rust effectively. A thinner (less viscous) mineral-oil-based anti-rust product followed by anti-rust wax can be more effective. [ according to whom? ] Application is easier in hot weather rather than cold because even when pre-heated, the products are viscous and don't flow and penetrate well on cold metal. [ citation needed ]
Aftermarket "underseals" can also be applied. They are particularly useful in high-impact areas like wheel arches. There are two types - drying and non-drying. The hardening and drying products are also known as "Shutz" and "Anti Stone Chip" with similar potential problems to the original factory underseals. [ citation needed ] These are available in black, white, grey and red colors and can be overpainted. These are best used for the area below the bumpers on cars that have painted metal body work in that location, rather than modern plastic deep bumpers. The bitumen based products do not dry and harden, so they cannot become brittle, like the confusingly named "Underbody Seal with added Waxoyl" made by Hammerite, which can be supplied in a Shutz type cartridge labelled "Shutz" for use with a Shutz compressor fed gun. [ 2 ] Mercedes bodyshops use a similar product supplied by Mercedes-Benz. [ 3 ] There are many manufacturers of similar products at varying prices, these are regularly group tested and reviewed in the classic car magazine press.
The non drying types contain anti-rust chemicals similar to those in anti-rust waxes. Petroleum-based rust-inhibitors provide several benefits, including the ability to creep over metal, covering missed areas. [ citation needed ] Additionally, a petroleum, solvent-free rust inhibitor remains on the metal surface, sealing it from rust-accelerating water and oxygen. Other benefits of petroleum-based rust protection include the self-healing properties that come naturally to oils, which helps undercoatings to resist abrasion caused by road sand and other debris. The disadvantage of using a petroleum-based coating is the film left over on surfaces, rendering these products too messy for top side exterior application, and unsafe in areas where it can be slipped on. They also cannot be painted. [ citation needed ]
There are aftermarket electronic "rustproofing" technologies claimed to prevent corrosion by "pushing" electrons into the car body, to limit the combination of oxygen and iron to form rust. The loss of electrons in paint is also claimed to be the cause of “paint oxidisation” and the electronic system is also supposed to protect the paint. [ 4 ] However, there is no peer reviewed scientific testing and validation supporting the use of these devices and corrosion control professionals find they do not work. [ 5 ] [ 6 ]
The rate at which vehicles corrode is dependent upon: [ original research? ]
Stainless steel , also known as "inox steel" does not stain, corrode, or rust as easily as ordinary steel. Pierre Berthier , a Frenchman, was the first to notice the rust-resistant properties of mixing chromium with alloys in 1821, which led to new metal treating and metallurgy processes, and eventually the creation of usable stainless steel. DeLorean cars had a fiberglass body structure with a steel backbone chassis, along with external brushed stainless-steel body panels.
Some cars have been made from aluminum, which may be more corrosion resistant than steel when exposed to water, but not to salt or certain other chemicals. [ citation needed ]
Weathering steel , often referred to by the genericised trademark COR-TEN steel and sometimes written without the hyphen as corten steel, is a group of steel alloys which were developed to eliminate the need for painting by forming a stable external layer of rust . U.S. Steel (USS) holds the registered trademark on the name COR-TEN. [ 7 ] The name COR-TEN refers to the two distinguishing properties of this type of steel : corrosion resistance and tensile strength . [ 8 ] | https://en.wikipedia.org/wiki/Rustproofing |
Rustum Roy (July 3, 1924 – August 26, 2010) was a physicist , born in India, who became a professor at Pennsylvania State University and was a leader in materials research . As an advocate for interdisciplinarity , he initiated a movement of materials research societies and, outside of his multiple areas of scientific and engineering expertise, wrote impassioned pleas about the need for a fusion of religion and science and humanistic causes.
Later in life he held visiting professorships in materials science at Arizona State University , and in medicine at the University of Arizona .
Roy was born in Ranchi , Bihar Province, India , the son of Narenda Kumar and Rajkumari Roy. [ 1 ]
Rustum took a Cambridge School Certificate from Saint Paul's School Darjeeling . Rustum studied physical chemistry at Patna University , gaining his bachelor's degree in 1942 and master's degree in 1944. The following year he began study at Pennsylvania State University and earned his Ph.D. in engineering ceramics in 1948. [ 2 ]
Rustum Roy married fellow materials scientist Della Marie Martin on June 8 that year. [ 1 ]
In 1962 he was named the first director of the Materials Research Laboratory at Penn State. [ 2 ] He edited the Proceedings [ 3 ] of a 1968 Conference on the chemistry of silicon carbide . The next year a national colloquy was held on materials science in the United States for which Roy edited the Proceedings . [ 4 ] In 1973 he edited the Proceedings [ 5 ] of a conference on phase transitions and their applications.
In 1974 Roy and Olaf Müller published The Major Ternary Structural Families with Springer-Verlag, which described the principal crystal structures of ternary compounds . The book received two brief reviews in materials trade journals. A cement journal reviewer said it would be "Useful to the practicing materials researcher, whether in industry or university, as well as the non-specialist who needs to become informed about particular materials." [ 6 ] A chemist writing for mineral processing readers, described its depth:
By 1991 he was a spokesperson for the movement and his lecture "New Materials: Fountainhead for New Technologies and New Science" was published by National Academy Press . [ 8 ] Roy presented the lecture to learned audiences in Washington, D.C.; Tokyo, Japan; New Delhi, Stockholm, Copenhagen, and London in 1991 and 92. He made the case for linking a technical need to investigative effort, which he terms "technology traction", noting that the method is productive and cost-effective in comparison to science conducted with other purposes.
Rustum Roy was referred to as "[o]ne of the legends of materials science" at the time of his death. [ 1 ]
Roy was elected as a member of the U.S. National Academy of Engineering in 1973. [ 9 ]
In 1953, Roy wrote a letter to Life magazine in response to the essay "Is Academic Freedom in Danger?" by Whittaker Chambers , stating:
Sirs: Chambers neglects to note that since people rarely read Congressional Records, they get their News more by headlines and the tenor of the times. Thus, most professors "know" or "feel" it is safer today to keep your mouth shut, and, if you open it, not to support any liberal or leftish views. Let Chambers continue to remind us of the very real perils of the Communist left. Fanatical preoccupation with self-preservation will lead to loss of more valuable things, not merely academic freedom, but freedom. Rustum Roy Assistant Professor The Pennsylvania State College State College, PA [ 10 ]
In 1977 Rustum Roy proposed [ 11 ] that the "science and engineering activity of a university ... [be organized] primarily around a dozen permanent mission-oriented interdisciplinary laboratories." To reach this conclusion he notes that "universities have been forced into new interdisciplinary patterns not only by the dollar sign but also by the inexorable logic that the real problems of society do not come in discipline-shaped blocks."
The daunting structural inertia of the university did not faze him:
Roy had no formal medical credentials but was an advocate of integrating science, medicine, and spirituality. In the inaugural issue of the Journal of Ayurveda and Integrative Medicine Roy contributed the article "Integrative medicine to tackle the problem of chronic diseases". He noted that chronic illness debilitates the lives of many seniors, and that medical interventions are often futile. He said "little of nothing is being spent on preventative medicine ", and cited the ayurveda concepts of "ahara" concerned with nutrition, and "vihara" with the conduct of life. He noted the exemplary work of Dean Ornish in addressing coronary artery disease as a hopeful innovation. [ 12 ]
In 2010, close to the end of his life, Roy co-wrote an article in the Huffington Post called "The Mythology Of Science-Based Medicine" with nonscientists Deepak Chopra and Larry Dossey , which David Gorski characterized as "an exercise that combines cherry-picking, logical fallacies, and whining, raising the last of these almost to an art form." [ 13 ] [ 14 ]
Roy married Della Martin Roy on June 8, 1948. Their three children are Neill R. Roy (deceased), [ 15 ] Jeremy R. Roy, and Ronnen A. Roy. [ 1 ]
Roy died on August 26, 2010, at the age of 86. [ 16 ] He was survived by his wife and children. [ 1 ]
Selection of U.S. patents for which Roy is the sole or primary inventor: | https://en.wikipedia.org/wiki/Rustum_Roy |
The rusty bolt effect is a form of radio interference due to interactions of the radio waves with dirty connections or corroded parts. [ 1 ] It is more properly known as passive intermodulation , [ 1 ] and can result from a variety of different causes such as ferromagnetic conduction metals, [ 2 ] or nonlinear microwave absorbers and loads. [ 3 ] Corroded materials on antennas, waveguides, or even structural elements, can act as one or more diodes . ( Crystal sets , early radio receivers, used the semiconductor properties of natural galena to demodulate the radio signal, and copper oxide was used in power rectifiers.) Galvanised fasteners and sheet roofing develop a coating of zinc oxide, a semiconductor commonly used for transient voltage suppression. This gives rise to undesired interference, including the generation of harmonics or intermodulation . [ 4 ] Rusty objects that should not be in the signal-path, including antenna structures, can also reradiate radio signals with harmonics and other unwanted signals. [ 5 ] As with all out-of-band noise, these spurious emissions can interfere with receivers.
This effect can cause radiated signals out of the desired band, even if the signal into a passive antenna is carefully band-limited. [ 6 ]
The transfer characteristic of an object can be represented as a power series :
Or, taking only the first few terms (which are most relevant),
For an ideal perfect linear object K 2 , K 3 , K 4 , K 5 , etc. are all zero. A good connection approximates this ideal case with sufficiently small values.
For a 'rusty bolt' (or an intentionally designed frequency mixer stage), K 2 , K 3 , K 4 , K 5 , etc. are not all zero. These higher-order terms result in generation of harmonics.
The following analysis applies the power series representation to an input sine-wave.
If the incoming signal is a sine wave {E in sin(ωt)}, (and taking only first-order terms), then the output can be written:
Clearly, the harmonic terms will be worse at high input signal amplitudes, as they increase exponentially with the amplitude of E in .
To understand the generation of nonharmonic terms ( frequency mixing ), a more complete formulation must be used, including higher-order terms. These terms, if significant, give rise to intermodulation distortion.
Hence the second-order, third-order, and higher-order mixing products can be greatly reduced by lowering the intensity of the original signals (f 1 , f 2 , f 3 , f 4 , …, f n ) | https://en.wikipedia.org/wiki/Rusty_bolt_effect |
Ruth Moufang (10 January 1905 – 26 November 1977) was a German mathematician .
She was born to German chemist Eduard Moufang and Else Fecht Moufang. Eduard Moufang was the son of Friedrich Carl Moufang (1848-1885) from Mainz, and Elisabeth von Moers from Mainz. Ruth Moufang's mother was Else Fecht, who was the daughter of Alexander Fecht (1848-1913) from Kehl and Ella Scholtz (1847-1921). Ruth was the younger of her parents' two daughters, having an elder sister named Erica. [ 1 ]
She studied mathematics at the University of Frankfurt . In 1931 she received her Ph.D. on projective geometry under the direction of Max Dehn , and in 1932 spent a fellowship year in Rome. After her year in Rome , she returned to Germany to lecture at the University of Königsberg and the University of Frankfurt. [ 1 ]
Denied permission to teach by the minister of education of Nazi Germany , she worked at Research and Development of Krupp (battleships, U-boats, tanks, howitzers, guns, etc.), where she became the first German woman with a doctorate to be employed as an industrial mathematician. At the end of World War II she was leading the Department of Applied Mathematics at the arms industry of Krupp.
In 1946 she was finally allowed to accept a teaching position at the University of Frankfurt, and in 1957 she became the first woman professor at the university. [ 2 ]
Moufang's research in projective geometry built upon the work of David Hilbert . She was responsible for ground-breaking work on non-associative algebraic structures , including the Moufang loops named after her. [ 1 ]
In 1933, Moufang showed Desargues's theorem does not hold in the Cayley plane . The Cayley plane uses octonion coordinates which do not satisfy the associative law . Such connections between geometry and algebra had been previously noted by Karl von Staudt and David Hilbert . [ 1 ] Ruth Moufang thus initiated a new branch of geometry called Moufang planes . [ 2 ]
She published 7 papers on this topic, these are
Moufang published only one paper on group theory, Einige Untersuchungen über geordenete Schiefkörper Ⓣ, which appeared in print in 1937. [ 1 ] | https://en.wikipedia.org/wiki/Ruth_Moufang |
This page provides supplementary chemical data on ruthenium(IV) oxide .
The handling of this chemical may require notable safety precautions. Safety information can be found on the Material Safety Datasheet ( MSDS ) for this chemical or from a reliable source, such as SIRI . | https://en.wikipedia.org/wiki/Ruthenium(IV)_oxide_(data_page) |
Ruthenium-iridium nanosized corals ( RuIr-NC ) are electrodes consisting of nanosized anisotropic ruthenium - iridium sheets for efficient electrolysis of water in acid discovered in the Kyoto University . [ 1 ] [ 2 ]
The RuIr-NC were discovered unintentionally at the Kyoto University, but then investigated and refined for the purpose of efficient electrolysis of water in acid and found to have very promising qualities in terms of performance and durability. [ 1 ]
As of 2021 the researchers at Kyoto University report their RuIr-NC are composed of 94% ruthenium and 6% iridium with the exposed hexagonal atomic arrangement corresponding to a hexagonal closed-packed (HCP) crystalline lattice plane crystal structure . The nanosheets take the form of 3 nm thick sheets with a mean diameter of 57 ± 7 nm. [ 1 ] [ 2 ] The researchers found them suitable for use as both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) electrodes. [ 1 ]
Their water splitting cell using RuIr-NC as both OER and HER electrodes is able to achieve 10 m A cm −2 geo at 1.485 V for 120 h without noticeable degradation. They report that, of the electrodes they evaluated for water electrolysis in acid, the RuIr-NC shows the highest intrinsic activity and stability. [ 1 ]
The RuIr-NC is obtained by adding a mixture of RuCl3 ·n H2O and H2IrCl6 aqueous solutions to triethylene glycol solution containing polyvinylpyrrolidone at 230 °C. [ 1 ]
The research team at Kyoto University published their work in February 2021 and presented it at the Chemical Society of Japan 101. General Meeting in March 2021. [ 3 ]
This electrochemistry -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Ruthenium-iridium_nanosized_coral |
This bibliography of Rutherford Aris contains a comprehensive listing of the scientific publications of Aris, including books, journal articles, and contributions to other published material. | https://en.wikipedia.org/wiki/Rutherford_Aris_bibliography |
Rutherford backscattering spectrometry (RBS) is an analytical technique used in materials science . Sometimes referred to as high-energy ion scattering (HEIS) spectrometry, RBS is used to determine the structure and composition of materials by measuring the backscattering of a beam of high energy ions (typically protons or alpha particles ) impinging on a sample.
Rutherford backscattering spectrometry is named after Lord Rutherford , a physicist sometimes referred to as the father of nuclear physics . Rutherford supervised a series of experiments carried out by Hans Geiger and Ernest Marsden between 1909 and 1914 studying the scattering of alpha particles through metal foils. While attempting to eliminate "stray particles" they believed to be caused by an imperfection in their alpha source, Rutherford suggested that Marsden attempt to measure backscattering from a gold foil sample. According to the then-dominant plum-pudding model of the atom, in which small negative electrons were spread through a diffuse positive region, backscattering of the high-energy positive alpha particles should have been nonexistent. At most small deflections should occur as the alpha particles passed almost unhindered through the foil. Instead, when Marsden positioned the detector on the same side of the foil as the alpha particle source, he immediately detected a noticeable backscattered signal. According to Rutherford, "It was quite the most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you." [ 1 ]
Rutherford interpreted the result of the Geiger–Marsden experiment as an indication of a Coulomb collision with a single massive positive particle. This led him to the conclusion that the atom's positive charge could not be diffuse but instead must be concentrated in a single massive core: the atomic nucleus . Calculations indicated that the charge necessary to accomplish this deflection was approximately 100 times the charge of the electron, close to the atomic number of gold. This led to the development of the Rutherford model of the atom in which a positive nucleus made up of N e positive particles, or protons , was surrounded by N orbiting electrons of charge -e to balance the nuclear charge. This model was eventually superseded by the Bohr atom , incorporating some early results from quantum mechanics .
If the energy of the incident particle is increased sufficiently, the Coulomb barrier is exceeded and the wavefunctions of the incident and struck particles overlap. This may result in nuclear reactions in certain cases, but frequently the interaction remains elastic , although the scattering cross-sections may fluctuate wildly as a function of energy and no longer be calculable analytically. This case is known as "Elastic (non-Rutherford) Backscattering Spectrometry" (EBS). There has recently been great progress in determining EBS scattering cross-sections, by solving Schrödinger's equation for each interaction [ citation needed ] . However, for the EBS analysis of matrices containing light elements, the utilization of experimentally measured [ 2 ] [ 3 ] scattering cross-section data is also considered to be a very credible option.
We describe Rutherford backscattering as an elastic , hard-sphere collision between a high kinetic energy particle from the incident beam (the projectile ) and a stationary particle located in the sample (the target ). Elastic in this context means that no energy is transferred between the incident particle and the stationary particle during the collision, and the state of the stationary particle is not changed. (Except that for a small amount of momentum, which is ignored.)
Nuclear interactions are generally not elastic, since a collision may result in a nuclear reaction, with the release of considerable quantities of energy. Nuclear reaction analysis (NRA) is useful for detecting light elements. However, this is not Rutherford scattering.
Considering the kinematics of the collision (that is, the conservation of momentum and kinetic energy), the energy E 1 of the scattered projectile is reduced from the initial energy E 0 :
where k is known as the kinematical factor , and
where particle 1 is the projectile, particle 2 is the target nucleus, and θ 1 {\displaystyle \theta _{1}} is the scattering angle of the projectile in the laboratory frame of reference (that is, relative to the observer). The plus sign is taken when the mass of the projectile is less than that of the target, otherwise the minus sign is taken.
While this equation correctly determines the energy of the scattered projectile for any particular scattering angle (relative to the observer), it does not describe the probability of observing such an event. For that we need the differential cross-section of the backscattering event:
where Z 1 {\displaystyle Z_{1}} and Z 2 {\displaystyle Z_{2}} are the atomic numbers of the incident and target nuclei. This equation is written in the centre of mass frame of reference and is therefore not a function of the mass of either the projectile or the target nucleus.
The scattering angle in the laboratory frame of reference θ 1 {\displaystyle \theta _{1}} is not the same as the scattering angle in the centre of mass frame of reference θ {\displaystyle \theta } (although for RBS experiments they are usually very similar). However, heavy ion projectiles can easily recoil lighter ions which, if the geometry is right, can be ejected from the target and detected. This is the basis of the Elastic Recoil Detection (ERD, with synonyms ERDA, FRS, HFS) technique. RBS often uses a He beam which readily recoils H, so simultaneous RBS/ERD is frequently done to probe the hydrogen isotope content of samples (although H ERD with a He beam above 1 MeV is not Rutherford: see http://www-nds.iaea.org/sigmacalc ). For ERD the scattering angle in the lab frame of reference is quite different from that in the centre of mass frame of reference.
Heavy ions cannot back scatter from light ones: it is kinematically prohibited. The kinematical factor must remain real, and this limits the permitted scattering angle in the laboratory frame of reference. In ERD it is often convenient to place the recoil detector at recoil angles large enough to prohibit signal from the scattered beam. The scattered ion intensity is always very large compared to the recoil intensity (the Rutherford scattering cross-section formula goes to infinity as the scattering angle goes to zero), and for ERD the scattered beam usually has to be excluded from the measurement somehow.
The singularity in the Rutherford scattering cross-section formula is unphysical of course. If the scattering cross-section is zero it implies that the projectile never comes close to the target, but in this case it also never penetrates the electron cloud surrounding the nucleus either. The pure Coulomb formula for the scattering cross-section shown above must be corrected for this screening effect , which becomes more important as the energy of the projectile decreases (or, equivalently, its mass increases).
While large-angle scattering only occurs for ions which scatter off target nuclei, inelastic small-angle scattering can also occur off the sample electrons. This results in a gradual decrease in the kinetic energy of incident ions as they penetrate into the sample, so that backscattering off interior nuclei occurs with a lower "effective" incident energy. Similarly backscattered ions lose energy to electrons as they exit the sample. The amount by which the ion energy is lowered after passing through a given distance is referred to as the stopping power of the material and is dependent on the electron distribution. This energy loss varies continuously with respect to distance traversed, so that stopping power is expressed as
For high energy ions stopping power is usually proportional to Z 2 E {\displaystyle {\frac {Z_{2}}{E}}} ; however, precise calculation of stopping power is difficult to carry out with any accuracy.
Stopping power (properly, stopping force ) has units of energy per unit length. It is generally given in thin film units, that is eV /(atom/cm 2 ) since it is measured experimentally on thin films whose thickness is always measured absolutely as mass per unit area, avoiding the problem of determining the density of the material which may vary as a function of thickness. Stopping power is now known for all materials at around 2%, see http://www.srim.org .
An RBS instrument generally includes three essential components:
Two common source/acceleration arrangements are used in commercial RBS systems, working in either one or two stages. One-stage systems consist of a He + source connected to an acceleration tube with a high positive potential applied to the ion source, and the ground at the end of the acceleration tube. This arrangement is simple and convenient, but it can be difficult to achieve energies of much more than 1 MeV due to the difficulty of applying very high voltages to the system.
Two-stage systems, or "tandem accelerators", start with a source of He − ions and position the positive terminal at the center of the acceleration tube. A stripper element included in the positive terminal removes electrons from ions which pass through, converting He − ions to He ++ ions. The ions thus start out being attracted to the terminal, pass through and become positive, and are repelled until they exit the tube at ground. This arrangement, though more complex, has the advantage of achieving higher accelerations with lower applied voltages: a typical tandem accelerator with an applied voltage of 750 kV can achieve ion energies of over 2 MeV. [ 6 ]
Detectors to measure backscattered energy are usually silicon surface barrier detectors , a very thin layer (100 nm) of P-type silicon on an N-type substrate forming a p-n junction . Ions which reach the detector lose some of their energy to inelastic scattering from the electrons, and some of these electrons gain enough energy to overcome the band gap between the semiconductor valence and conduction bands . This means that each ion incident on the detector will produce some number of electron-hole pairs which is dependent on the energy of the ion. These pairs can be detected by applying a voltage across the detector and measuring the current, providing an effective measurement of the ion energy. The relationship between ion energy and the number of electron-hole pairs produced will be dependent on the detector materials, the type of ion and the efficiency of the current measurement; energy resolution is dependent on thermal fluctuations. After one ion is incident on the detector, there will be some dead time before the electron-hole pairs recombine in which a second incident ion cannot be distinguished from the first. [ 7 ]
Angular dependence of detection can be achieved by using a movable detector, or more practically by separating the surface barrier detector into many independent cells which can be measured independently, covering some range of angles around direct (180 degrees) back-scattering. Angular dependence of the incident beam is controlled by using a tiltable sample stage.
The energy loss of a backscattered ion is dependent on two processes: the energy lost in scattering events with sample nuclei, and the energy lost to small-angle scattering from the sample electrons. The first process is dependent on the scattering cross-section of the nucleus and thus on its mass and atomic number. For a given measurement angle, nuclei of two different elements will therefore scatter incident ions to different degrees and with different energies, producing separate peaks on an N(E) plot of measurement count versus energy. These peaks are characteristic of the elements contained in the material, providing a means of analyzing the composition of a sample by matching scattered energies to known scattering cross-sections. Relative concentrations can be determined by measuring the heights of the peaks.
The second energy loss process, the stopping power of the sample electrons, does not result in large discrete losses such as those produced by nuclear collisions. Instead it creates a gradual energy loss dependent on the electron density and the distance traversed in the sample. This energy loss will lower the measured energy of ions which backscatter from nuclei inside the sample in a continuous manner dependent on the depth of the nuclei. The result is that instead of the sharp backscattered peaks one would expect on an N(E) plot, with the width determined by energy and angular resolution, the peaks observed trail off gradually towards lower energy as the ions pass through the depth occupied by that element. Elements which only appear at some depth inside the sample will also have their peak positions shifted by some amount which represents the distance an ion had to traverse to reach those nuclei.
In practice, then, a compositional depth profile can be determined from an RBS N(E) measurement. The elements contained by a sample can be determined from the positions of peaks in the energy spectrum. Depth can be determined from the width and shifted position of these peaks, and relative concentration from the peak heights. This is especially useful for the analysis of a multilayer sample, for example, or for a sample with a composition which varies more continuously with depth.
This kind of measurement can only be used to determine elemental composition; the chemical structure of the sample cannot be determined from the N(E) profile. However, it is possible to learn something about this through RBS by examining the crystal structure. This kind of spatial information can be investigated by taking advantage of blocking and channeling.
To fully understand the interaction of an incident beam of nuclei with a crystalline structure, it is necessary to comprehend two more key concepts: blocking and channeling .
When a beam of ions with parallel trajectories is incident on a target atom, scattering off that atom will prevent collisions in a cone-shaped region "behind" the target relative to the beam. This occurs because the repulsive potential of the target atom bends close ion trajectories away from their original path, and is referred to as blocking . The radius of this blocked region, at a distance L from the original atom, is given by
When an ion is scattered from deep inside a sample, it can then re-scatter off a second atom, creating a second blocked cone in the direction of the scattered trajectory. This can be detected by carefully varying the detection angle relative to the incident angle.
Channeling is observed when the incident beam is aligned with a major symmetry axis of the crystal. Incident nuclei which avoid collisions with surface atoms are excluded from collisions with all atoms deeper in the sample, due to blocking by the first layer of atoms. When the interatomic distance is large compared to the radius of the blocked cone, the incident ions can penetrate many times the interatomic distance without being backscattered. This can result in a drastic reduction of the observed backscattered signal when the incident beam is oriented along one of the symmetry directions, allowing determination of a sample's regular crystal structure. Channeling works best for very small blocking radii, i.e. for high-energy, low-atomic-number incident ions such as He + .
The tolerance for the deviation of the ion beam angle of incidence relative to the symmetry direction depends on the blocking radius, making the allowable deviation angle proportional to
While the intensity of an RBS peak is observed to decrease across most of its width when the beam is channeled, a narrow peak at the high-energy end of larger peak will often be observed, representing surface scattering from the first layer of atoms. The presence of this peak opens the possibility of surface sensitivity for RBS measurements.
In addition, channeling of ions can also be used to analyze a crystalline sample for lattice damage. [ 10 ] If atoms within the target are displaced from their crystalline lattice site, this will result in a higher backscattering yield in relation to a perfect crystal. By comparing the spectrum from a sample being analyzed to that from a perfect crystal, and that obtained at a random (non-channeling) orientation (representative of a spectrum from an amorphous sample), it is possible to determine the extent of crystalline damage in terms of a fraction of displaced atoms. Multiplying this fraction by the density of the material when amorphous then also gives an estimate for the concentration of displaced atoms. The energy at which the increased backscattering occurs can also be used to determine the depth at which the displaced atoms are and a defect depth profile can be built up as a result.
While RBS is generally used to measure the bulk composition and structure of a sample, it is possible to obtain some information about the structure and composition of the sample surface. When the signal is channeled to remove the bulk signal, careful manipulation of the incident and detection angles can be used to determine the relative positions of the first few layers of atoms, taking advantage of blocking effects.
The surface structure of a sample can be changed from the ideal in a number of ways. The first layer of atoms can change its distance from subsequent layers ( relaxation ); it can assume a different two-dimensional structure than the bulk ( reconstruction ); or another material can be adsorbed onto the surface. Each of these cases can be detected by RBS. For example, surface reconstruction can be detected by aligning the beam in such a way that channeling should occur, so that only a surface peak of known intensity should be detected. A higher-than-usual intensity or a wider peak will indicate that the first layers of atoms are failing to block the layers beneath, i.e. that the surface has been reconstructed. Relaxations can be detected by a similar procedure with the sample tilted so the ion beam is incident at an angle selected so that first-layer atoms should block backscattering at a diagonal; that is, from atoms which are below and displaced from the blocking atom. A higher-than-expected backscattered yield will indicate that the first layer has been displaced relative to the second layer, or relaxed. Adsorbate materials will be detected by their different composition, changing the position of the surface peak relative to the expected position.
RBS has also been used to measure processes which affect the surface differently from the bulk by analyzing changes in the channeled surface peak. A well-known example of this is the RBS analysis of the premelting of lead surfaces by Frenken, Maree and van der Veen. In an RBS measurement of the Pb (110) surface, a well-defined surface peak which is stable at low temperatures was found to become wider and more intense as temperature increase past two-thirds of the bulk melting temperature. The peak reached the bulk height and width as temperature reached the melting temperature. This increase in the disorder of the surface, making deeper atoms visible to the incident beam, was interpreted as pre-melting of the surface, and computer simulations of the RBS process produced similar results when compared with theoretical pre-melting predictions. [ 11 ]
RBS has also been combined with nuclear microscopy , in which a focused ion beam is scanned across a surface in a manner similar to a scanning electron microscope . The energetic analysis of backscattered signals in this kind of application provides compositional information about the surface, while the microprobe itself can be used to examine features such as periodic surface structures. [ 12 ] | https://en.wikipedia.org/wiki/Rutherford_backscattering_spectrometry |
Ruy J. Guerra B. de Queiroz (born January 11, 1958, in Recife ) is an associate professor at Universidade Federal de Pernambuco and holds significant works in the research fields of Mathematical logic, proof theory, foundations of mathematics and philosophy of mathematics. [ 1 ] He is the founder of the Workshop on Logic, Language, Information and Computation (WoLLIC), which has been organised annually since 1994, typically in June or July.
Ruy de Queiroz received his B.Eng in Electrical Engineering from Escola Politecnica de Pernambuco in 1980, his M.Sc in Informatics from Universidade Federal de Pernambuco in 1984, and his Ph.D. in Computing from the Imperial College , London in 1990, for which he defended the Dissertation Proof Theory and Computer Programming. An Essay into the Logical Foundations of Computation .
In the late 1980s, Ruy de Queiroz has offered a reformulation of Martin-Löf type theory based on a novel reading of Wittgenstein ’s "meaning-is-use", where the explanation of the consequences of a given proposition gives the meaning to the logical constant dominating the proposition. This amounts to a non-dialogical interpretation of logical constants via the effect of elimination rules over introduction rules, which finds a parallel in Paul Lorenzen 's and Jaakko Hintikka 's dialogue/game-semantics. This led to a type theory called "Meaning as Use Type Theory". [ 2 ] In reference to the use of Wittgenstein's dictum, he has shown that the aspect concerning the explanation of the consequences of a proposition is present since a very early date when in a letter to Bertrand Russell , where Wittgenstein refers to the universal quantifier only having meaning when one sees what follows from it. [ 3 ]
Since later in the 1990s, Ruy de Queiroz has been engaged, jointly with Dov Gabbay , in a program of providing a general account of the functional interpretation of classical and non-classical logics via the notion of labeled natural deduction. As a result, novel accounts of the functional interpretation of the existential quantifier, as well as the notion of propositional equality, were put forward, the latter allowing for a recasting of Richard Statman 's notion of direct computation, and a novel approach to the dichotomy "intensional versus extensional" accounts of propositional equality via the Curry–Howard correspondence .
Since the early 2000s, Ruy de Queiroz has been investigating, jointly with Anjolina de Oliveira , a geometric perspective of natural deduction based on a graph-based account of Kneale 's symmetric natural deduction. [ 4 ]
Ruy de Queiroz has taught several disciplines related to logic and theoretical computer science, including Set Theory, Recursion Theory (as a follow-up to a course given by Solomon Feferman), Logic for Computer Science, Discrete Mathematics, Theory of Computation, Proof Theory, Model Theory, Foundations of Cryptography. He has had seven Ph.D. students in the fields of Mathematical Logic and Theoretical Computer Science. | https://en.wikipedia.org/wiki/Ruy_de_Queiroz |
In mathematics , an R-function , or Rvachev function , is a real-valued function whose sign does not change if none of the signs of its arguments change; that is, its sign is determined solely by the signs of its arguments. [ 1 ] [ 2 ]
Interpreting positive values as true and negative values as false , an R-function is transformed into a "companion" Boolean function (the two functions are called friends ). For instance, the R-function ƒ ( x , y ) = min( x , y ) is one possible friend of the logical conjunction (AND). R-functions are used in computer graphics and geometric modeling in the context of implicit surfaces and the function representation . They also appear in certain boundary-value problems , and are also popular in certain artificial intelligence applications, where they are used in pattern recognition .
R-functions were first proposed by Vladimir Logvinovich Rvachev [ ru ] [ 3 ] ( Russian : Влади́мир Логвинович Рвачёв ) in 1963, though the name, "R-functions", was given later on by Ekaterina L. Rvacheva-Yushchenko, in memory of their father, Logvin Fedorovich Rvachev ( Russian : Логвин Фёдорович Рвачёв ). | https://en.wikipedia.org/wiki/Rvachev_function |
The Rwanda Space Agency (RSA) is Rwanda 's agency for aerospace research and economic development. Its responsibilities include advising the government of Rwanda on space policies, to implement those policies, to promote Rwanda's aerospace industry, and to conduct aerospace research. [ 1 ] It was established in 2021. [ 2 ]
In 2017, the Rwanda Utilities Regulatory Authority (RURA) and Rwanda's Ministry of Defense created a Space Working Group. [ 3 ] This coordinated and promoted the various aerospace projects around the country culminating in the launch of Rwanda's first satellite, RWASAT-1, in 2019 through the Japan Aerospace and Exploration Agency (JAXA) . [ 4 ]
Since the RSA was established, Rwanda has rapidly grown its ambitions. In October of 2021, the RSA requested orbital slots for almost 330,000 satellites. In 2022, its CEO, Col. Francis Ngabo, signed the Artemis Accords on the norms for space exploration and use of astronomical objects. [ 5 ]
Much of the RSA's activity involves earth observation . This includes greenhouse gas monitoring, disaster management, and economic and social development. [ 6 ]
Rwanda's first satellite, RWASAT-1, monitored soil moisture levels and provided data for crop yield estimates as a part of the RSA's economic development initiative. Its second, nicknamed Icyerekezo, helped provide satellite internet service to the remote Nkombo Island on Lake Kivu . [ 7 ]
In 2022, the RSA took charge of the Rwanda Climate Observatory. [ 8 ] It now monitors the emissions of six greenhouse gases. | https://en.wikipedia.org/wiki/Rwanda_Space_Agency |
RxQual is used in GSM and is a part of the Network Measurement Reports (NMR). [ 1 ]
This is an integer value which can be between 0 and 7 and reflects the quality of voice.
0 is the best quality, 7 is the worst.
Each RxQual value corresponds to an estimated number of bit errors in a number of bursts.
There are two types of RxQual values, FULL and SUB .
We use RxQual SUB when we have DTX DL activated because RxQual FULL values will not be reliable, because they will use Bit error rate (BER) measurements when nothing has been sent, what leads to a very high BER and a poor RxQual.
If DTX DL is deactivated, is better to use RxQual FULL values, they are more precise, because it uses all frames on the SACCH multiframe, whether they have been transmitted from the base station or not.
The official definition of RxQual is given in Chapter 8.2.4 of GSM TS 05.08 (ETSI TS 100 911), later superseded by 3GPP TS 45.008. [ 2 ] | https://en.wikipedia.org/wiki/Rxqual |
The Rybczynski theorem was developed in 1955 by the Polish -born English economist Tadeusz Rybczynski (1923–1998). It states that at constant relative goods prices, a rise in the endowment of one factor will lead to a more than proportional expansion of the output in the sector which uses that factor intensively, and an absolute decline of the output of the other good.
In the context of the Heckscher–Ohlin model of international trade , regions opened to trade often take the relative prices of goods as given. When there is a change in relative factor supply, the Rybczynski theorem explains the output changes and how factors are reallocated between the two sectors. In essence, both factors will move towards the sector that uses the factor that sees an increase in the relative supply more intensively, leading to a rise in output in this sector and an absolute decrease in output in the other sector.
Eventually, across both countries, market forces would return the system toward equality of production in regard to input prices such as wages (the state of factor price equalization ).
The Rybczynski theorem displays how changes in an endowment affects the outputs of the goods when full employment is sustained. The theorem is useful in analyzing the effects of capital investment, immigration and emigration within the context of a Heckscher-Ohlin model. Consider the diagram below, depicting a labour constraint in red and a capital constraint in blue. Suppose production occurs initially on the production possibility frontier (PPF) at point A.
Suppose there is an increase in the labour endowment. This will cause an outward shift in the labour constraint. The PPF and thus production will shift to point B. Production of clothing, the labour-intensive good, will rise from C 1 to C 2 . Production of cars, the capital-intensive good, will fall from S 1 to S 2 .
If the endowment of capital rose the capital constraint would shift out causing an increase in car production and a decrease in clothing production. Since the labour constraint is steeper than the capital constraint, cars are capital-intensive and clothing is labor-intensive.
In general, an increase in a country's endowment of a factor will cause an increase in output of the good which uses that factor intensively, and a decrease in the output of the other good. | https://en.wikipedia.org/wiki/Rybczynski_theorem |
Rydberg ionization spectroscopy is a spectroscopy technique in which multiple photons are absorbed by an atom causing the removal of an electron to form an ion . [ 1 ]
The ionization threshold energy of atoms and small molecules are typically larger than the photon energies that are most easily available experimentally. However, it can be possible to span this ionization threshold energy if the photon energy is resonant with an intermediate electronically excited state. While it is often possible to observe the lower Rydberg levels in conventional spectroscopy of atoms and small molecules, Rydberg states are even more important in laser ionization experiments. Laser spectroscopic experiments often involve ionization through a photon energy resonance at an intermediate level, with an unbound final electron state and an ionic core. On resonance for phototransitions permitted by selection rules, the intensity of the laser in combination with the excited state lifetime makes ionization an expected outcome. This RIS approach and variations permit sensitive detection of specific species.
High photon intensity experiments can involve multiphoton processes with the absorption of integer multiples of the photon energy. In experiments that involve a multiphoton resonance, the intermediate is often a Rydberg state, and the final state is often an ion. The initial state of the system, photon energy, angular momentum and other selection rules can help in determining the nature of the intermediate state. This approach is exploited in resonance enhanced multiphoton ionization spectroscopy (REMPI). An advantage of this spectroscopic technique is that the ions can be detected with almost complete efficiency and even resolved for their mass. It is also possible to gain additional information by performing experiments to look at the energy of the liberated photoelectron in these experiments. (Compton and Johnson pioneered the development of REMPI [ citation needed ] )
The same approach that produces an ionization event can be used to access the dense manifold of near-threshold Rydberg states with laser experiments. These experiments often involve a laser operating at one wavelength to access the intermediate Rydberg state and a second wavelength laser to access the near-threshold Rydberg state region. Because of the photoabsorption selection rules, these Rydberg electrons are expected to be in highly elliptical angular momentum states. It is the Rydberg electrons excited to nearly circular angular momentum states that are expected to have the longest lifetimes. The conversion between a highly elliptical and a nearly circular near-threshold Rydberg state might happen in several ways, including encountering small stray electric fields .
Zero electron kinetic energy (ZEKE) spectroscopy [ 2 ] was developed with the idea of collecting only the resonance ionization photoelectrons that have extremely low kinetic energy. The technique involves waiting for a period of time after a resonance ionization experiment and then pulsing an electric field to collect the lowest energy photoelectrons in a detector. Typically, ZEKE experiments utilize two different tunable lasers. One laser photon energy is tuned to be resonant with the energy of an intermediate state. (This may be resonant with an excited state at a multiphoton transition.) Another photon energy is tuned to be close to the ionization threshold energy. The technique worked extremely well and demonstrated energy resolution that was significantly better than the laser bandwidth. It turns out that it was not the photoelectrons that were detected in ZEKE. The delay between the laser and the electric field pulse selected the longest lived and most circular Rydberg states closest to the energy of the ion core. The population distribution of surviving long-lived near threshold Rydberg states is close to the laser energy bandwidth. The electric field pulse Stark shifts the near-threshold Rydberg states and vibrational autoionization occurs. ZEKE has provided a significant advance in the study of the vibrational spectroscopy of molecular ions. Schlag, Peatman and Müller-Dethlefs originated ZEKE spectroscopy. [ citation needed ]
Mass analyzed threshold ionization (MATI) was developed with idea of collecting the mass of the ions in a ZEKE experiment. [ 3 ]
MATI offered a mass resolution advantage to ZEKE. Because MATI also exploits vibrational autoionization of near-threshold Rydberg states, it also can offer a comparable resolution with the laser bandwidth. This information can be indispensable in understanding a variety of systems.
Photo-induced Rydberg ionization (PIRI) [ 4 ] was developed following REMPI experiments on electronic autoionization of low-lying Rydberg states of carbon dioxide . In REMPI photoelectron experiments, it was determined that a two-photon ionic core photoabsorption process (followed by prompt electronic autoionization) could dominate the direct single photon absorption in the ionization of some Rydberg states of carbon dioxide. These sorts of two excited electron systems had already been under study in the atomic physics , but there the experiments involved high order Rydberg states. PIRI works because electronic autoionization can dominate direct photoionization ( photoionization ). The circularized near-threshold Rydberg state is more likely to undergo a core photoabsorption than to absorb a photon and directly ionize the Rydberg state. PIRI extends the near-threshold spectroscopic techniques to allow access to the electronic states (including dissociative molecular states and other hard to study systems) as well as the vibrational states of molecular ions. | https://en.wikipedia.org/wiki/Rydberg_ionization_spectroscopy |
Rydberg matter [ 1 ] is an exotic phase of matter formed by Rydberg atoms ; it was predicted around 1980 by É. A. Manykin , M. I. Ozhovan and P. P. Poluéktov . [ 2 ] [ 3 ] It has been formed from various elements like caesium , [ 4 ] potassium , [ 5 ] hydrogen [ 6 ] [ 7 ] and nitrogen ; [ 8 ] studies have been conducted on theoretical possibilities like sodium , beryllium , magnesium and calcium . [ 9 ] It has been suggested to be a material that diffuse interstellar bands may arise from. [ 10 ] Circular [ 11 ] Rydberg states, where the outermost electron is found in a planar circular orbit, are the most long-lived, with lifetimes of up to several hours, [ 12 ] and are the most common. [ 13 ] [ 14 ] [ 15 ]
Rydberg matter consists of usually [ 17 ] hexagonal [ 18 ] [ 16 ] planar [ 19 ] clusters ; these cannot be very big because of the retardation effect caused by the finite velocity of the speed of light. [ 19 ] Hence, they are not gases or plasmas; nor are they solids or liquids; they are most similar to dusty plasmas with small clusters in a gas. Though Rydberg matter can be studied in the laboratory by laser probing , [ 20 ] the largest cluster reported consists of only 91 atoms, [ 7 ] but it has been shown to be behind extended clouds in space [ 10 ] [ 21 ] and the upper atmosphere of planets. [ 22 ] Bonding in Rydberg matter is caused by delocalisation of the high-energy electrons to form an overall lower energy state. [ 3 ] The way in which the electrons delocalise is to form standing waves on loops surrounding nuclei, creating quantised angular momentum and the defining characteristics of Rydberg matter. It is a generalised metal by way of the quantum numbers influencing loop size but restricted by the bonding requirement for strong electron correlation; [ 19 ] it shows exchange-correlation properties similar to covalent bonding. [ 23 ] Electronic excitation and vibrational motion of these bonds can be studied by Raman spectroscopy . [ 24 ]
Due to reasons still debated by the physics community because of the lack of methods to observe clusters, [ 27 ] Rydberg matter is highly stable against disintegration by emission of radiation; the characteristic lifetime of a cluster at n = 12 is 25 seconds. [ 26 ] [ 28 ] Reasons given include the lack of overlap between excited and ground states, the forbidding of transitions between them and exchange-correlation effects hindering emission through necessitating tunnelling [ 23 ] that causes a long delay in excitation decay. [ 25 ] Excitation plays a role in determining lifetimes, with a higher excitation giving a longer lifetime; [ 26 ] n = 80 gives a lifetime comparable to the age of the Universe. [ 29 ]
In ordinary metals, interatomic distances are nearly constant through a wide range of temperatures and pressures; this is not the case with Rydberg matter, whose distances and thus properties vary greatly with excitations. A key variable in determining these properties is the principal quantum number n that can be any integer greater than 1; the highest values reported for it are around 100. [ 29 ] [ 30 ] Bond distance d in Rydberg matter is given by
where a 0 is the Bohr radius . The approximate factor 2.9 was first experimentally determined, then measured with rotational spectroscopy in different clusters. [ 16 ] Examples of d calculated this way, along with selected values of the density D , are given in the adjacent table.
Like bosons that can be condensed to form Bose–Einstein condensates , Rydberg matter can be condensed, but not in the same way as bosons. The reason for this is that Rydberg matter behaves similarly to a gas, meaning that it cannot be condensed without removing the condensation energy; ionisation occurs if this is not done. All solutions to this problem so far involve using an adjacent surface in some way, the best being evaporating the atoms of which the Rydberg matter is to be formed from and leaving the condensation energy on the surface. [ 31 ] Using caesium atoms, graphite-covered surfaces and thermionic converters as containment, the work function of the surface has been measured to be 0.5 eV, [ 32 ] indicating that the cluster is between the ninth and fourteenth excitation levels. [ 25 ]
The overview [ 33 ] provides information on Rydberg matter and possible applications in developing clean energy, catalysts, researching space phenomena, and usage in sensors.
The research claiming to create ultradense hydrogen Rydberg matter (with interatomic spacing of ~2.3 pm: many orders of magnitude less than in most solid matter) is disputed: [ 34 ]
″The paper of Holmlid and Zeiner-Gundersen makes claims that would be truly revolutionary if they were true. We have shown that they violate some fundamental and very well established laws in a rather direct manner. We believe we share this scepticism with most of the scientific community. The response to the theories of Holmlid is perhaps most clearly reflected in the reference list of their article. Out of 114 references, 36 are not coauthored by Holmlid. And of these 36, none address the claims made by him and his co-authors. This is so much more remarkable because the claims, if correct, would revolutionize quantum science, add at least two new forms of hydrogen, of which one is supposedly the ground state of the element, discover an extremely dense form of matter, discover processes that violate baryon number conservation, in addition to solving humanity’s need for energy practically in perpetuity.″ | https://en.wikipedia.org/wiki/Rydberg_matter |
A Rydberg molecule is an electronically excited chemical species . Electronically excited molecular states are generally quite different in character from electronically excited atomic states. However, particularly for highly electronically excited molecular systems, the ionic core interaction with an excited electron can take on the general aspects of the interaction between the proton and the electron in the hydrogen atom. The spectroscopic assignment of these states follows the Rydberg formula , named after the Swedish physicist Johannes Rydberg , and they are called Rydberg states of molecules. Rydberg series are associated with partially removing an electron from the ionic core.
Each Rydberg series of energies converges on an ionization energy threshold associated with a particular ionic core configuration. These quantized Rydberg energy levels can be associated with the quasiclassical Bohr atomic picture. The closer you get to the ionization threshold energy, the higher the principal quantum number, and the smaller the energy difference between near threshold Rydberg states. As the electron is promoted to higher energy levels in a Rydberg series, the spatial excursion of the electron from the ionic core increases and the system is more like the Bohr quasiclassical picture.
The Rydberg states of molecules with low principal quantum numbers can interact with the other excited electronic states of the molecule. This can cause shifts in energy. The assignment of molecular Rydberg states often involves following a Rydberg series from intermediate to high principal quantum numbers. The energy of Rydberg states can be refined by including a correction called the quantum defect in the Rydberg formula. The quantum defect correction can be associated with the presence of a distributed ionic core.
The experimental study of molecular Rydberg states has been conducted with traditional methods for generations. However, the development of laser-based techniques such as Resonance Ionization Spectroscopy has allowed relatively easy access to these Rydberg molecules as intermediates. This is particularly true for Resonance Enhanced Multiphoton Ionization ( REMPI ) spectroscopy, since multiphoton processes involve different selection rules from single photon processes. The study of high principal quantum number Rydberg states has spawned a number of spectroscopic techniques. These "near threshold Rydberg states" can have long lifetimes, particularly for the higher orbital angular momentum states that do not interact strongly with the ionic core.
Rydberg molecules can condense to form clusters of Rydberg matter which has an extended lifetime against de-excitation.
Dihelium (He 2 * ) was the first known Rydberg molecule. [ 1 ]
In 2009, a different kind of Rydberg molecule was finally created by researchers from the University of Stuttgart . There, the interaction between a Rydberg atom and a ground state atom leads to a novel bond type . Two rubidium atoms were used to create the molecule which survived for 18 microseconds. [ 2 ] [ 3 ]
In 2015, a 'trilobite' Rydberg molecule was observed by researchers from the University of Oklahoma . [ 4 ] This molecule was theorized in 2000 and is characterized by an electron density distribution that resembles the shape of a trilobite when plotted in cylindrical coordinates . [ 5 ] These molecules have lifetimes of tens of microseconds and electric dipole moments of up to 2000 Debye .
In 2016, a butterfly Rydberg molecule was observed by a collaboration involving researchers from the Kaiserslautern University of Technology and Purdue University . [ 6 ] [ 7 ] A butterfly Rydberg molecule is a weak pairing of a Rydberg atom and a ground state atom that is enhanced by the presence of a shape resonance in the scattering between the Rydberg electron and the ground state atom. This new kind of atomic bond was theorized in 2002 and is characterized by an electron density distribution that resembles the shape of a butterfly. [ 8 ] As a consequence of the unconventional binding mechanism, butterfly Rydberg molecules show peculiar properties such as multiple vibrational ground states at different bond lengths and giant dipole moments in excess of 500 debye. | https://en.wikipedia.org/wiki/Rydberg_molecule |
A Rydberg polaron is an exotic quasiparticle , created at low temperatures, in which a very large atom contains other ordinary atoms in the space between the nucleus and the electrons. [ 1 ] For the formation of this atom, scientists had to combine two fields of atomic physics: Bose–Einstein condensates and Rydberg atoms . Rydberg atoms are formed by exciting a single atom into a high-energy state, in which the electron is very far from the nucleus. Bose–Einstein condensates are a state of matter that is produced at temperatures close to absolute zero.
Polarons are induced by using a laser to excite Rydberg atoms contained as impurities in a Bose–Einstein condensate. In those Rydberg atoms, the average distance between the electron and its nucleus can be as large as several hundred nanometres, which is more than a thousand times the radius of a hydrogen atom. [ 2 ] Under these circumstances, the distance between the nucleus and the electron of the excited Rydberg atoms is higher than the average distance between the atoms of the condensate. As a result, some atoms lie inside the orbit of the Rydberg atom's electron.
As the atoms don't have an electric charge, they only produce a minimal force on the electron. However, the electron is slightly scattered at the neutral atoms, without even leaving its orbit, and the weak bond that is generated between the Rydberg atom and the atoms inside of it, tying them together, is known as the Rydberg polaron. The excitation was predicted by theorists at Harvard University in 2016 [ 3 ] and confirmed in 2018 by spectroscopy in an experiment using a strontium Bose–Einstein condensate. [ 4 ] Theoretically, up to 170 ordinary strontium atoms could fit closely inside the new orbital of the Rydberg atom, depending on the radius of the Rydberg atom and the density of the Bose–Einstein condensate. [ 2 ] The theoretical work for the experiment was performed by theorists at Vienna University of Technology and Harvard University , [ 5 ] while the actual experiment and observation took place at Rice University in Houston, Texas. | https://en.wikipedia.org/wiki/Rydberg_polaron |
The Rydberg states [ 1 ] of an atom or molecule are electronically excited states with energies that follow the Rydberg formula as they converge on an ionic state with an ionization energy . Although the Rydberg formula was developed to describe atomic energy levels, it has been used to describe many other systems that have electronic structure roughly similar to atomic hydrogen. [ 2 ] In general, at sufficiently high principal quantum numbers , an excited electron-ionic core system will have the general character of a hydrogenic system and the energy levels will follow the Rydberg formula. Rydberg states have energies converging on the energy of the ion. The ionization energy threshold is the energy required to completely liberate an electron from the ionic core of an atom or molecule. In practice, a Rydberg wave packet is created by a laser pulse on a hydrogenic atom and thus populates a superposition of Rydberg states. [ 3 ] Modern investigations using pump-probe experiments show molecular pathways – e.g. dissociation of (NO) 2 – via these special states. [ 4 ]
Rydberg series describe the energy levels associated with partially removing an electron from the ionic core. Each Rydberg series converges on an ionization energy threshold associated with a particular ionic core configuration. These quantized Rydberg energy levels can be associated with the quasiclassical Bohr atomic picture. The closer you get to the ionization threshold energy, the higher the principal quantum number, and the smaller the energy difference between "near threshold Rydberg states." As the electron is promoted to higher energy levels, the spatial excursion of the electron from the ionic core increases and the system is more like the Bohr quasiclassical picture.
The energy of Rydberg states can be refined by including a correction called the quantum defect in the Rydberg formula. The "quantum defect" correction is associated with the presence of a distributed ionic core. Even for many electronically excited molecular systems, the ionic core interaction with an excited electron can take on the general aspects of the interaction between the proton and the electron in the hydrogen atom. The spectroscopic assignment of these states follows the Rydberg formula and they are called Rydberg states of molecules.
Although the energy formula of Rydberg series is a result of hydrogen-like atom structure, Rydberg states are also present in molecules. Wave functions of high Rydberg states are very diffuse and span diameters that approach infinity. [ attribution needed ] [ vague ] As a result, any isolated neutral molecule behaves like a hydrogen-like atom at the Rydberg limit. For molecules with multiple stable monovalent cations, multiple Rydberg series may exist. Because of the complexity of molecular spectra, low-lying Rydberg states of molecules are often mixed with valence states with similar energy and are thus not pure Rydberg states. [ 5 ] | https://en.wikipedia.org/wiki/Rydberg_state |
Ryōji Noyori ( 野依 良治 , Noyori Ryōji , born September 3, 1938) is a Japanese chemist . He won the Nobel Prize in Chemistry in 2001, Noyori shared a half of the prize with William S. Knowles for the study of chirally catalyzed hydrogenations ; the second half of the prize went to K. Barry Sharpless for his study in chirally catalyzed oxidation reactions ( Sharpless epoxidation ). [ 2 ] [ 3 ] [ 4 ] [ 5 ] [ 6 ] [ 7 ] [ 8 ]
Ryōji Noyori was born in Kobe, Japan . Early in his school days Ryoji was interested in physics. His interest was kindled by the famous physicist Hideki Yukawa (1949 Nobel Prize in Physics winner), a close friend of his father. Later, he became fascinated with chemistry, after hearing a presentation on nylon at an industrial exposition. He saw the power of chemistry as being the ability to "produce high value from almost nothing". He was a student at the School of Engineering (Department of Industrial Chemistry) of the Kyoto University , where he graduated in 1961. He subsequently obtained a Master's degree in Industrial Chemistry from the Graduate School of Engineering of the Kyoto University . Between 1963 and 1967, he was a research associate at the School of Engineering of the Kyoto University , and an instructor in the research group of Hitoshi Nozaki . Noyori obtained a Doctor of Engineering degree (DEng) from the Kyoto University in 1967. [ 9 ] He became an associate professor at the same university in 1968. After postdoctoral work with Elias J. Corey at Harvard he returned to Nagoya, becoming a full professor in 1972. He is still based at Nagoya, and served as president of RIKEN , a multi-site national research initiative with an annual budget of $800 million, from 2003 to 2015. [ 10 ]
Noyori believes strongly in the power of catalysis and of green chemistry ; in a 2005 article he argued for the pursuit of "practical elegance in synthesis". [ 11 ] In this article he stated that " our ability to devise straightforward and practical chemical syntheses is indispensable to the survival of our species. " Elsewhere he has said that " Research is for nations and mankind, not for researchers themselves. " He encourages scientists to be politically active: " Researchers must spur public opinions and government policies toward constructing the sustainable society in the 21st century. " [ 12 ]
Noyori is currently a chairman of the Education Rebuilding Council, which was set up by Japan's PM Shinzō Abe after he came to power in 2006. [ 13 ]
Noyori is most famous for asymmetric hydrogenation using as catalysts complexes of rhodium and ruthenium , particularly those based on the BINAP ligand . Asymmetric hydrogenation of an alkene in the presence of (( S )- BINAP )Ru( OAc ) 2 is used for the commercial production of enantiomerically pure (97% ee ) naproxen , a nonsteriodal anti-inflammatory drug . The antibacterial agent levofloxacin is manufactured by asymmetric hydrogenation of ketones in the presence of a Ru(II) BINAP halide complex. [ citation needed ]
He has also worked on other asymmetric processes . Each year 3000 tonnes (after new expansion) of menthol are produced (in 94% ee ) by Takasago International Corporation , using Noyori's method for isomerisation of allylic amines . [ 14 ]
More recently with Philip G. Jessop, Noyori has developed an industrial process for the manufacture of N,N - dimethylformamide from hydrogen , dimethylamine and supercritical carbon dioxide in the presence of RuCl 2 (P(CH 3 ) 3 ) 4 as catalyst. [ 15 ]
The Ryoji Noyori Prize is named in his honour. In 2000 Noyori became Honorary Doctor at the University of Rennes 1 , where he taught in 1995, [ 16 ] and in 2005, he became Honorary Doctor at Technical University of Munich and RWTH Aachen University , Germany. Noyori was elected a Foreign Member of the Royal Society (ForMemRS) in 2005 . [ 1 ] and an Honorary Doctorate degree from the Institute of Chemical Technology , Mumbai (formerly known as UDCT) on the 23rd day of February 2018.
He has also been awarded: | https://en.wikipedia.org/wiki/Ryōji_Noyori |
In information theory , the Rényi entropy is a quantity that generalizes various notions of entropy , including Hartley entropy , Shannon entropy , collision entropy , and min-entropy . The Rényi entropy is named after Alfréd Rényi , who looked for the most general way to quantify information while preserving additivity for independent events. [ 1 ] [ 2 ] In the context of fractal dimension estimation, the Rényi entropy forms the basis of the concept of generalized dimensions . [ 3 ]
The Rényi entropy is important in ecology and statistics as index of diversity . The Rényi entropy is also important in quantum information , where it can be used as a measure of entanglement . In the Heisenberg XY spin chain model, the Rényi entropy as a function of α can be calculated explicitly because it is an automorphic function with respect to a particular subgroup of the modular group . [ 4 ] [ 5 ] In theoretical computer science , the min-entropy is used in the context of randomness extractors .
The Rényi entropy of order α {\displaystyle \alpha } , where 0 < α < ∞ {\displaystyle 0<\alpha <\infty } and α ≠ 1 {\displaystyle \alpha \neq 1} , is defined as [ 1 ] H α ( X ) = 1 1 − α log ( ∑ i = 1 n p i α ) . {\displaystyle \mathrm {H} _{\alpha }(X)={\frac {1}{1-\alpha }}\log \left(\sum _{i=1}^{n}p_{i}^{\alpha }\right).} It is further defined at α = 0 , 1 , ∞ {\displaystyle \alpha =0,1,\infty } as H α ( X ) = lim γ → α H γ ( X ) . {\displaystyle \mathrm {H} _{\alpha }(X)=\lim _{\gamma \to \alpha }\mathrm {H} _{\gamma }(X).}
Here, X {\displaystyle X} is a discrete random variable with possible outcomes in the set A = { x 1 , x 2 , . . . , x n } {\displaystyle {\mathcal {A}}=\{x_{1},x_{2},...,x_{n}\}} and corresponding probabilities p i ≐ Pr ( X = x i ) {\displaystyle p_{i}\doteq \Pr(X=x_{i})} for i = 1 , … , n {\displaystyle i=1,\dots ,n} . The resulting unit of information is determined by the base of the logarithm , e.g. shannon for base 2, or nat for base e .
If the probabilities are p i = 1 / n {\displaystyle p_{i}=1/n} for all i = 1 , … , n {\displaystyle i=1,\dots ,n} , then all the Rényi entropies of the distribution are equal: H α ( X ) = log n {\displaystyle \mathrm {H} _{\alpha }(X)=\log n} .
In general, for all discrete random variables X {\displaystyle X} , H α ( X ) {\displaystyle \mathrm {H} _{\alpha }(X)} is a non-increasing function in α {\displaystyle \alpha } .
Applications often exploit the following relation between the Rényi entropy and the α -norm of the vector of probabilities: H α ( X ) = α 1 − α log ( ‖ P ‖ α ) . {\displaystyle \mathrm {H} _{\alpha }(X)={\frac {\alpha }{1-\alpha }}\log \left({\left\|P\right\|}_{\alpha }\right).} Here, the discrete probability distribution P = ( p 1 , … , p n ) {\displaystyle P=(p_{1},\dots ,p_{n})} is interpreted as a vector in R n {\displaystyle \mathbb {R} ^{n}} with p i ≥ 0 {\displaystyle p_{i}\geq 0} and ∑ i = 1 n p i = 1 {\textstyle \sum _{i=1}^{n}p_{i}=1} .
The Rényi entropy for any α ≥ 0 {\displaystyle \alpha \geq 0} is Schur concave . Proven by the Schur–Ostrowski criterion.
As α {\displaystyle \alpha } approaches zero, the Rényi entropy increasingly weighs all events with nonzero probability more equally, regardless of their probabilities. In the limit for α → 0 {\displaystyle \alpha \to 0} , the Rényi entropy is just the logarithm of the size of the support of X . The limit for α → 1 {\displaystyle \alpha \to 1} is the Shannon entropy . As α {\displaystyle \alpha } approaches infinity, the Rényi entropy is increasingly determined by the events of highest probability.
H 0 ( X ) {\displaystyle \mathrm {H} _{0}(X)} is log n {\displaystyle \log n} where n {\displaystyle n} is the number of non-zero probabilities. [ 6 ] If the probabilities are all nonzero, it is simply the logarithm of the cardinality of the alphabet ( A {\displaystyle {\mathcal {A}}} ) of X {\displaystyle X} , sometimes called the Hartley entropy of X {\displaystyle X} , H 0 ( X ) = log n = log | A | {\displaystyle \mathrm {H} _{0}(X)=\log n=\log |{\mathcal {A}}|\,}
The limiting value of H α {\displaystyle \mathrm {H} _{\alpha }} as α → 1 {\displaystyle \alpha \to 1} is the Shannon entropy : [ 7 ] H 1 ( X ) ≡ lim α → 1 H α ( X ) = − ∑ i = 1 n p i log p i {\displaystyle \mathrm {H} _{1}(X)\equiv \lim _{\alpha \to 1}\mathrm {H} _{\alpha }(X)=-\sum _{i=1}^{n}p_{i}\log p_{i}}
Collision entropy , sometimes just called "Rényi entropy", refers to the case α = 2 {\displaystyle \alpha =2} , H 2 ( X ) = − log ∑ i = 1 n p i 2 = − log P ( X = Y ) , {\displaystyle \mathrm {H} _{2}(X)=-\log \sum _{i=1}^{n}p_{i}^{2}=-\log P(X=Y),} where X {\displaystyle X} and Y {\displaystyle Y} are independent and identically distributed . The collision entropy is related to the index of coincidence . It is the negative logarithm of the Simpson diversity index .
In the limit as α → ∞ {\displaystyle \alpha \rightarrow \infty } , the Rényi entropy H α {\displaystyle \mathrm {H} _{\alpha }} converges to the min-entropy H ∞ {\displaystyle \mathrm {H} _{\infty }} : H ∞ ( X ) ≐ min i ( − log p i ) = − ( max i log p i ) = − log max i p i . {\displaystyle \mathrm {H} _{\infty }(X)\doteq \min _{i}(-\log p_{i})=-(\max _{i}\log p_{i})=-\log \max _{i}p_{i}\,.}
Equivalently, the min-entropy H ∞ ( X ) {\displaystyle \mathrm {H} _{\infty }(X)} is the largest real number b such that all events occur with probability at most 2 − b {\displaystyle 2^{-b}} .
The name min-entropy stems from the fact that it is the smallest entropy measure in the family of Rényi entropies.
In this sense, it is the strongest way to measure the information content of a discrete random variable.
In particular, the min-entropy is never larger than the Shannon entropy .
The min-entropy has important applications for randomness extractors in theoretical computer science :
Extractors are able to extract randomness from random sources that have a large min-entropy; merely having a large Shannon entropy does not suffice for this task.
That H α {\displaystyle \mathrm {H} _{\alpha }} is non-increasing in α {\displaystyle \alpha } for any given distribution of probabilities p i {\displaystyle p_{i}} ,
which can be proven by differentiation, [ 8 ] as − d H α d α = 1 ( 1 − α ) 2 ∑ i = 1 n z i log ( z i / p i ) = 1 ( 1 − α ) 2 D K L ( z ‖ p ) {\displaystyle -{\frac {d\mathrm {H} _{\alpha }}{d\alpha }}={\frac {1}{(1-\alpha )^{2}}}\sum _{i=1}^{n}z_{i}\log(z_{i}/p_{i})={\frac {1}{(1-\alpha )^{2}}}D_{KL}(z\|p)} which is proportional to Kullback–Leibler divergence (which is always non-negative), where z i = p i α / ∑ j = 1 n p j α {\textstyle z_{i}=p_{i}^{\alpha }/\sum _{j=1}^{n}p_{j}^{\alpha }} . In particular, it is strictly positive except when the distribution is uniform.
At the α → 1 {\displaystyle \alpha \to 1} limit, we have − d H α d α → 1 2 ∑ i p i ( ln p i + H ( p ) ) 2 {\textstyle -{\frac {d\mathrm {H} _{\alpha }}{d\alpha }}\to {\frac {1}{2}}\sum _{i}p_{i}{\left(\ln p_{i}+H(p)\right)}^{2}} .
In particular cases inequalities can be proven also by Jensen's inequality : [ 9 ] [ 10 ] log n = H 0 ≥ H 1 ≥ H 2 ≥ H ∞ . {\displaystyle \log n=\mathrm {H} _{0}\geq \mathrm {H} _{1}\geq \mathrm {H} _{2}\geq \mathrm {H} _{\infty }.}
For values of α > 1 {\displaystyle \alpha >1} , inequalities in the other direction also hold. In particular, we have [ 11 ] [ 12 ] H 2 ≤ 2 H ∞ . {\displaystyle \mathrm {H} _{2}\leq 2\mathrm {H} _{\infty }.}
On the other hand, the Shannon entropy H 1 {\displaystyle \mathrm {H} _{1}} can be arbitrarily high for a random variable X {\displaystyle X} that has a given min-entropy. An example of this is given by the sequence of random variables X n ∼ { 0 , … , n } {\displaystyle X_{n}\sim \{0,\ldots ,n\}} for n ≥ 1 {\displaystyle n\geq 1} such that P ( X n = 0 ) = 1 / 2 {\displaystyle P(X_{n}=0)=1/2} and P ( X n = x ) = 1 / ( 2 n ) {\displaystyle P(X_{n}=x)=1/(2n)} since H ∞ ( X n ) = log 2 {\displaystyle \mathrm {H} _{\infty }(X_{n})=\log 2} but H 1 ( X n ) = ( log 2 + log 2 n ) / 2 {\displaystyle \mathrm {H} _{1}(X_{n})=(\log 2+\log 2n)/2} .
As well as the absolute Rényi entropies, Rényi also defined a spectrum of divergence measures generalising the Kullback–Leibler divergence . [ 13 ]
The Rényi divergence of order α {\displaystyle \alpha } or alpha-divergence of a distribution P from a distribution Q is defined to be D α ( P ‖ Q ) = 1 α − 1 log ( ∑ i = 1 n p i α q i α − 1 ) = 1 α − 1 log E i ∼ p [ ( p i / q i ) α − 1 ] {\displaystyle {\begin{aligned}D_{\alpha }(P\Vert Q)&={\frac {1}{\alpha -1}}\log \left(\sum _{i=1}^{n}{\frac {p_{i}^{\alpha }}{q_{i}^{\alpha -1}}}\right)\\[1ex]&={\frac {1}{\alpha -1}}\log \mathbb {E} _{i\sim p}\left[{\left(p_{i}/q_{i}\right)}^{\alpha -1}\right]\,\end{aligned}}} when 0 < α < ∞ {\displaystyle 0<\alpha <\infty } and α ≠ 1 {\displaystyle \alpha \neq 1} . We can define the Rényi divergence for the special values α = 0, 1, ∞ by taking a limit, and in particular the limit α → 1 gives the Kullback–Leibler divergence.
Some special cases:
The Rényi divergence is indeed a divergence , meaning simply that D α ( P ‖ Q ) {\displaystyle D_{\alpha }(P\|Q)} is greater than or equal to zero, and zero only when P = Q . For any fixed distributions P and Q , the Rényi divergence is nondecreasing as a function of its order α , and it is continuous on the set of α for which it is finite, [ 13 ] or for the sake of brevity, the information of order α obtained if the distribution P is replaced by the distribution Q . [ 1 ]
A pair of probability distributions can be viewed as a game of chance in which one of the distributions defines official odds and the other contains the actual probabilities. Knowledge of the actual probabilities allows a player to profit from the game. The expected profit rate is connected to the Rényi divergence as follows [ 14 ] E x p e c t e d R a t e = 1 R D 1 ( b ‖ m ) + R − 1 R D 1 / R ( b ‖ m ) , {\displaystyle {\rm {ExpectedRate}}={\frac {1}{R}}\,D_{1}(b\|m)+{\frac {R-1}{R}}\,D_{1/R}(b\|m)\,,} where m {\displaystyle m} is the distribution defining the official odds (i.e. the "market") for the game, b {\displaystyle b} is the investor-believed distribution and R {\displaystyle R} is the investor's risk aversion (the Arrow–Pratt relative risk aversion ).
If the true distribution is p {\displaystyle p} (not necessarily coinciding with the investor's belief b {\displaystyle b} ), the long-term realized rate converges to the true expectation which has a similar mathematical structure [ 14 ] R e a l i z e d R a t e = 1 R ( D 1 ( p ‖ m ) − D 1 ( p ‖ b ) ) + R − 1 R D 1 / R ( b ‖ m ) . {\displaystyle {\rm {RealizedRate}}={\frac {1}{R}}\,{\Big (}D_{1}(p\|m)-D_{1}(p\|b){\Big )}+{\frac {R-1}{R}}\,D_{1/R}(b\|m)\,.}
The value α = 1 {\displaystyle \alpha =1} , which gives the Shannon entropy and the Kullback–Leibler divergence , is the only value at which the chain rule of conditional probability holds exactly: H ( A , X ) = H ( A ) + E a ∼ A [ H ( X | A = a ) ] {\displaystyle \mathrm {H} (A,X)=\mathrm {H} (A)+\mathbb {E} _{a\sim A}{\big [}\mathrm {H} (X|A=a){\big ]}} for the absolute entropies, and D K L ( p ( x | a ) p ( a ) ‖ m ( x , a ) ) = D K L ( p ( a ) ‖ m ( a ) ) + E p ( a ) { D K L ( p ( x | a ) ‖ m ( x | a ) ) } , {\displaystyle D_{\mathrm {KL} }(p(x|a)p(a)\|m(x,a))=D_{\mathrm {KL} }(p(a)\|m(a))+\mathbb {E} _{p(a)}\{D_{\mathrm {KL} }(p(x|a)\|m(x|a))\},} for the relative entropies.
The latter in particular means that if we seek a distribution p ( x , a ) which minimizes the divergence from some underlying prior measure m ( x , a ) , and we acquire new information which only affects the distribution of a , then the distribution of p ( x | a ) remains m ( x | a ) , unchanged.
The other Rényi divergences satisfy the criteria of being positive and continuous, being invariant under 1-to-1 co-ordinate transformations, and of combining additively when A and X are independent, so that if p ( A , X ) = p ( A ) p ( X ) , then H α ( A , X ) = H α ( A ) + H α ( X ) {\displaystyle \mathrm {H} _{\alpha }(A,X)=\mathrm {H} _{\alpha }(A)+\mathrm {H} _{\alpha }(X)\;} and D α ( P ( A ) P ( X ) ‖ Q ( A ) Q ( X ) ) = D α ( P ( A ) ‖ Q ( A ) ) + D α ( P ( X ) ‖ Q ( X ) ) . {\displaystyle D_{\alpha }(P(A)P(X)\|Q(A)Q(X))=D_{\alpha }(P(A)\|Q(A))+D_{\alpha }(P(X)\|Q(X)).}
The stronger properties of the α = 1 {\displaystyle \alpha =1} quantities allow the definition of conditional information and mutual information from communication theory.
The Rényi entropies and divergences for an exponential family admit simple expressions [ 15 ] H α ( p F ( x ; θ ) ) = 1 1 − α ( F ( α θ ) − α F ( θ ) + log E p [ e ( α − 1 ) k ( x ) ] ) {\displaystyle \mathrm {H} _{\alpha }(p_{F}(x;\theta ))={\frac {1}{1-\alpha }}\left(F(\alpha \theta )-\alpha F(\theta )+\log E_{p}\left[e^{(\alpha -1)k(x)}\right]\right)} and D α ( p : q ) = J F , α ( θ : θ ′ ) 1 − α {\displaystyle D_{\alpha }(p:q)={\frac {J_{F,\alpha }(\theta :\theta ')}{1-\alpha }}} where J F , α ( θ : θ ′ ) = α F ( θ ) + ( 1 − α ) F ( θ ′ ) − F ( α θ + ( 1 − α ) θ ′ ) {\displaystyle J_{F,\alpha }(\theta :\theta ')=\alpha F(\theta )+(1-\alpha )F(\theta ')-F(\alpha \theta +(1-\alpha )\theta ')} is a Jensen difference divergence.
The Rényi entropy in quantum physics is not considered to be an observable , due to its nonlinear dependence on the density matrix . (This nonlinear dependence applies even in the special case of the Shannon entropy.) It can, however, be given an operational meaning through the two-time measurements (also known as full counting statistics) of energy transfers [ citation needed ] .
The limit of the quantum mechanical Rényi entropy as α → 1 {\displaystyle \alpha \to 1} is the von Neumann entropy . | https://en.wikipedia.org/wiki/Rényi_entropy |
The Résal effect (named after the French engineer Louis-Jean Résal ) is a structural engineering term which refers to the way the compressive force acting on a flange of a tapered beam reduces the effective shear force acting on the beam. [ 1 ] [ 2 ]
This article about a civil engineering topic is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Résal_effect |
The Römpp Encyclopedia Natural Products is an encyclopedia of natural products written by German chemists who specialize in this area of science. It is published by Thieme Medical Publishers . [ 1 ] [ 2 ]
This Germany -related article is a stub . You can help Wikipedia by expanding it .
This article about a chemistry -related book is a stub . You can help Wikipedia by expanding it .
This article about an encyclopedia is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Römpp_Encyclopedia_Natural_Products |
The Röntgen equivalent physical or rep (symbol rep ) is a legacy unit of absorbed dose first introduced by Herbert Parker in 1945 to replace an improper application of the roentgen unit to biological tissue. [ 1 ] It is the absorbed energetic dose before the biological efficiency of the radiation is factored in. The rep has variously been defined as 83 or 93 ergs per gram of tissue (8.3/9.3 mGy ) [ 2 ] or per cm 3 of tissue. [ 3 ]
At the time, this was thought to be the amount of energy deposited by 1 roentgen. [ 4 ] Improved measurements have since found that one roentgen of air kerma deposits 8.77 mGy in dry air, or 9.6 mGy in soft tissue, but the rep was defined as a fixed number of ergs per unit gram. [ 5 ]
A 1952 handbook from the US National Bureau of Standards affirms that "The numerical coefficient of the rep has been deliberately changed to 93, instead of the earlier 83, to agree with L. H. Gray 's 'energy-unit'." [ 6 ] Gray's 'energy unit' was " one roentgen of hard gamma resulted in about 93 ergs per gram energy absorption in water". The lower range value of 83.8 ergs was the value in air corresponding to wet tissue. [ 7 ] The rep was commonly used until the 1960s, [ 8 ] but was gradually displaced by the rad starting in 1954 and later the gray starting in 1977.
This radioactivity –related article is a stub . You can help Wikipedia by expanding it .
This standards - or measurement -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Röntgen_equivalent_physical |
The Rössler Prize , offered by the ETH Zurich Foundation , is a monetary prize that has been awarded annually since 2009 to a promising young tenured professor of the ETH Zurich in the middle of an accelerating career. [ 1 ] The prize of 200,000 Swiss Francs is financed by the returns from an endowment made by Max Rössler , an alumnus of the ETH. [ 2 ] The prize money has to be used for the research of the laureate. [ 3 ] | https://en.wikipedia.org/wiki/Rössler_Prize |
The Rüchardt experiment , [ 1 ] [ 2 ] [ 3 ] invented by Eduard Rüchardt , is a famous experiment in thermodynamics , which determines the ratio of the molar heat capacities of a gas, i.e. the ratio of C p {\displaystyle C_{\text{p}}} (heat capacity at constant pressure) and C V {\displaystyle C_{\text{V}}} (heat capacity at constant volume) and is denoted by γ {\displaystyle \gamma } ( gamma , for ideal gas) or κ {\displaystyle \kappa } ( kappa , isentropic exponent, for real gas). It arises because the temperature of a gas changes as pressure changes.
The experiment directly yields the heat capacity ratio or adiabatic index of the gas , which is the ratio of the heat capacity at constant pressure to heat capacity at constant volume. The results are sometimes also known as the isentropic expansion factor.
If a gas is compressed adiabatically , i.e. without outflow of heat from the system, the temperature rises (due to the pressure increase) at a higher rate with respect to isothermal compression, where the performed work is dissipated as heat. The exponent, κ {\displaystyle \kappa } , with which the expansion of the gas can be calculated by the application of heat is called the isentropic – or adiabatic coefficient. Its value is determined by the Rüchardt experiment.
An adiabatic and reversible running state change is isentropic ( entropy S remains the same as temperature T changes). The technique is usually an adiabatic change of state. For example, a steam turbine is not isentropic, as friction, choke and shock processes produce entropy .
A typical experiment, [ 4 ] consists of a glass tube of volume V , and of cross-section A , which is open on one of its end. A ball (or sometimes a piston) of mass m with the same cross-section, creating an air-tight seal, is allowed to fall under gravity g . The entrapped gas is first compressed by the weight of the piston, which leads to an increase in temperature. In the course of the piston falling, a gas cushion is created, and the piston bounces. Harmonic oscillation occurs, which slowly damps . The result is a rapid sequence of expansion and compression of the gas. The picture shows a revised version of the original Rüchardt setup: the sphere oscillating inside the tube is here replaced by a "breast-pump" which acts as an oscillating glass-piston; in this new setup three sensors allow to measure in real-time the piston oscillations as well as the pressure and temperature oscillations of the air inside the bottle (more details may be found in [ 5 ] )
According to Figure 1, the piston inside the tube is in equilibrium if the pressure P inside the glass bottle is equal to the sum of the atmospheric pressure P 0 and the pressure increase due to the piston weight :
When the piston moves beyond the equilibrium by a distance d x , the pressure changes by d p . A force F will be exerted on the piston, equal to
According to Newton's second law of motion , this force will create an acceleration a equal to
As this process is adiabatic , the equation for ideal gas ( Poisson's equation ) is:
It follows using differentiation from the equation above that:
If the piston moves by a distance d x {\displaystyle dx} in the glass tube, the corresponding change in volume will be
By substituting equation Eq. 5b into equation Eq. 3 , we can rewrite Eq. 3 as follows:
Solving this equation and rearranging terms yields the differential equation of a harmonic oscillation from which the angular frequency ω can be deduced:
From this, the period T of harmonic oscillation performed by the ball is:
Measuring the period of oscillation T and the relative pressure P in the tube yields the equation for the adiabatic exponent: | https://en.wikipedia.org/wiki/Rüchardt_experiment |
S -(2-Aminoethyl)isothiourea dihydrobromide , [ 2 ] commonly knwn as AET , is a isothiouronium -group-containing reducing agent with textbook uses as a disulfide reducing agent. Though it does not have a free thiol group (-SH) like 2-mercaptoethanol and dithiothreitol (DTT), it reacts with water to decompose transiently into thiol intermediates that acts on disulfide in a manner to these containing free -SH groups.
One application of AET is in hematology where red cells are treated with AET to create PNH-like cells. [ 3 ] | https://en.wikipedia.org/wiki/S-(2-Aminoethyl)isothiuronium_bromide_hydrobromide |
S-100 is an electronic nautical chart data format standard, first published by the IHO in 2010. [ 1 ] Development was begun in 2001. [ 2 ] S-100 has a number of child standards covering related areas, [ 1 ] including
This computing article is a stub . You can help Wikipedia by expanding it .
This article about a specific oceanic location or ocean current is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/S-100_(chart) |
S-200 is a bioremediation product used to clean up oil spills . It is an oleophilic nitrogen-phosphorus nutrient that promotes the growth of micro-organisms that degrade hydrocarbons (such as oil and fuel). S-200 bonds to the hydrocarbon to eliminate the need to reapply in tidal or rain events. S-200 is identified as a bioremediation accelerator and as such, does not contain bacterial cultures, but rather contributes to the establishment of a robust microbial population. In the laboratory, considerable biodegradation to alkanes was seen over the course of treatment. Field trials have yielded inconsistent results.
The product was developed by International Environmental Products, a US company based around S-200 as its product. [ 1 ]
After laboratory and field trials, S-200 was the only bioremediation process selected by the Spanish Department of National Parks for the final cleanup of the Galician coastline following the Prestige oil tanker spill . [ citation needed ]
The effects of the product were studied on a beach affected by the spill] off the coast of Spain in 2002. A study concluded that it enhanced the biodegradation rate of specific compounds, but did not establish whether it had improved the visible aspect of the beach, detached stuck oil, or reduced weathered oil. [ which? ] Other compounds, such as uric acid and lecithin , may be more effective than S-200, but wash off in tidal areas or rain events and must be applied continuously. In 2006, other researchers summarized the findings of experiments on Prestige-affected coastal areas, concluding that oloephilic substances such as S-200 were of "limited effectiveness. [ 2 ]
In 2006, a field bioremediation assay was conducted by the Department of Microbiology, University of Barcelona on the use of S-200 ten months after the Prestige heavy fuel-oil spill on a beach of the Cantabrian coast in northern Spain. The field survey indicated that the product enhanced the biodegradation rate, particularly of high molecular weight n-alkanes, alkylcyclohexanes, and benzenes, and alkylated PAHs. The most significant molecular bioremediation indicators were the depletion of diasteranes and C-27 sterane components. [ 3 ]
However, the study was confined to analysis of specific compounds, and did not report whether the application of S-200 caused a decrease in the amount of weathered oil, the detachment of any oil that had been stuck, or any improvement to the visible appearance of the beach. [ 4 ]
In 2006, other researchers summarized the findings of experiments on Prestige -affected coastal areas, concluding that oloephilic fertilizers such as S-200 were of "limited effectiveness". [ 5 ]
A 2007 test by researchers at the Technical University of Crete comparing a control to treatment by S-200 and treatment by uric acid and lecithin found that the hydrocarbon degradation in a period of 7 days was greater with the uric acid and lecithin treatment than it was with the S-200 treatment and the control. [ 6 ] | https://en.wikipedia.org/wiki/S-200_(bioremediation) |
S -Acylation is the process of chemically linking a molecule to another molecule via a thioester bond. [ 1 ] Protein S -acylation is a sub-type of S -acylation where the first of those molecules is a protein , and connected to the second through a cysteine amino acid . [ 1 ] A prominent type of protein S -acylation is palmitoylation , which promotes lipid membrane association of the protein, for instance to the plasma membrane , Golgi apparatus , or inner nuclear membrane . [ 2 ] | https://en.wikipedia.org/wiki/S-Acylation |
S -Adenosyl- L -homocysteine ( SAH ) is the biosynthetic precursor to homocysteine . [ 1 ] SAH is formed by the demethylation of S -adenosyl- L -methionine . [ 2 ] [ 3 ] Adenosylhomocysteinase converts SAH into homocysteine and adenosine .
DNA methyltransferases are inhibited by SAH. [ 4 ] Two S -adenosyl- L -homocysteine cofactor products can bind the active site of DNA methyltransferase 3B and prevent the DNA duplex from binding to the active site , which inhibits DNA methylation . [ 5 ]
This biochemistry article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/S-Adenosyl-L-homocysteine |
S -Adenosylmethioninamine is a substrate that is required for the biosynthesis of polyamines including spermidine , spermine , and thermospermine . [ 1 ] It is produced by decarboxylation of S -adenosyl methionine .
This biochemistry article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/S-Adenosylmethioninamine |
S -Adenosylmethionine synthetase ( EC 2.5.1.6 ), also known as methionine adenosyltransferase ( MAT ), is an enzyme that creates S -adenosylmethionine (also known as AdoMet, SAM or SAMe) by reacting methionine (a non-polar amino acid ) and ATP (the basic currency of energy). [ 1 ]
AdoMet is a methyl donor for transmethylation. It gives away its methyl group and is also the propylamino donor in polyamine biosynthesis . S-adenosylmethionine synthesis can be considered the rate-limiting step of the methionine cycle. [ 2 ]
As a methyl donor SAM allows DNA methylation . Once DNA is methylated, it switches the genes off and therefore, S-adenosylmethionine can be considered to control gene expression . [ 3 ]
SAM is also involved in gene transcription , cell proliferation , and production of secondary metabolites. [ 4 ] Hence SAM synthetase is fast becoming a drug target, in particular for the following diseases: depression , dementia , vacuolar myelopathy, liver injury, migraine , osteoarthritis , and as a potential cancer chemopreventive agent. [ 5 ]
This article discusses the protein domains that make up the SAM synthetase enzyme and how these domains contribute to its function. More specifically, this article explores the shared pseudo-3-fold symmetry that makes the domains well-adapted to their functions. [ 6 ]
This enzyme catalyses the following chemical reaction
A computational comparative analysis of vertebrate genome sequences have identified a cluster of 6 conserved hairpin motifs in the 3'UTR of the MAT2A messenger RNA (mRNA) transcript. [ 7 ] The predicted hairpins (named A-F) have strong evolutionary conservation and 3 of the predicted RNA structures (hairpins A, C and D) have been confirmed by in-line probing analysis. No structural changes were observed for any of the hairpins in the presence of metabolites SAM, S-adenosylhomocysteine or L-Methionine. They are proposed to be involved in transcript stability and their functionality is currently under investigation. [ 7 ]
The S-adenosylmethionine synthetase enzyme is found in almost every organism bar parasites which obtain AdoMet from their host. Isoenzymes are found in bacteria, budding yeast and even in mammalian mitochondria. Most MATs are homo-oligomers and the majority are tetramers. The monomers are organised into three domains formed by nonconsecutive stretches of the sequence, and the subunits interact through a large flat hydrophobic surface to form the dimers. [ 8 ]
In molecular biology the protein domain S-adenosylmethionine synthetase N terminal domain is found at the N-terminal of the enzyme.
The N terminal domain is well conserved across different species. This may be due to its important function in substrate and cation binding. The residues involved in methionine binding are found in the N-terminal domain. [ 8 ]
The N terminal region contains two alpha helices and four beta strands . [ 6 ]
The precise function of the central domain has not been fully elucidated, but it is thought to be important in aiding catalysis.
The central region contains two alpha helices and four beta strands . [ 6 ]
In molecular biology , the protein domain S-adenosylmethionine synthetase, C-terminal domain refers to the C terminus of the S-adenosylmethionine synthetase
The function of the C-terminal domain has been experimentally determined as being important for cytoplasmic localisation. The residues are scattered along the C-terminal domain sequence however once the protein folds, they position themselves closely together. [ 3 ]
The C-terminal domains contains two alpha-helices and four beta-strands. [ 6 ]
(See Template:Leucine metabolism in humans – this diagram does not include the pathway for β-leucine synthesis via leucine 2,3-aminomutase) | https://en.wikipedia.org/wiki/S-Adenosylmethionine_synthetase_enzyme |
Simultaneous GPS ( S-GPS ) is a method to allow a GPS reception and CDMA communications to operate simultaneously in a mobile phone.
Ordinarily, cellular geolocation and a built-in GPS receiver is used to determine the location of an E911 call made from CDMA phones. By using a time-multiplexed scheme called TM-GPS , the reception of the telephone call and the GPS signal are alternated one after the other, requiring only one radio receiver .
Simultaneous GPS allows a cellphone to receive both GPS and voice data at the same time, which improves sensitivity and allows service providers to offer location-based services . [ 1 ] The use of two radios with a single antenna imparts new design challenges, such as leakage of the voice transmitter signal into the GPS receiver circuitry. [ 2 ] The commercial availability of S-GPS chipsets from manufacturers such as Qualcomm , has led to adoption of the method in newer handsets. [ 3 ]
This article about wireless technology is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/S-GPS |
S-LINK , for simple link interface , is a high-performance data acquisition standard developed at CERN for collecting information from particle accelerators and other sources. Unlike similar systems, S-LINK is based on the idea that data will be collected and stored by computers at both ends of the link, as opposed to a "dumb" devices collecting data to be stored on a "smart" computer. Having a full computer at both ends allows S-LINK to be very thin, primarily defining the logical standards used to feed data at high speed from the motherboards to the link hardware interfaces. [ citation needed ]
S-LINK started in 1995 in response to problems collecting data from the new ATLAS experiment at CERN. ATLAS was extensively instrumented with stand-alone computers, which sent data via a variety of methods to be collected on various servers. S-LINK was seen as a way to provide a single mechanism for forwarding the data from the collection to the link hardware with extremely low latency. Generally the S-LINK hardware provided functionality that would normally be provided by networking (or other) drivers running on the host CPU , thereby tying up cycles and introducing delays. [ citation needed ]
S-LINK used a 32- bit bus running up to 66 MHz, allowing for throughout up to 264 MB /s. The "link side" was typically connected to optical fibre for transmission to the collecting machines, known as the read-out motherboard , or ROMB . Data could also be sent back to the front-end motherboard or FEMB , typically for flow control purposes at a much lower speed. [ 1 ] | https://en.wikipedia.org/wiki/S-LINK |
S -Methyl methanethiosulfonate , also known as MMTS , is an organosulfur compound with the chemical formula C H 3 − S O 2 −S−CH 3 . It is the S - methyl ester of methanethiosulfonic acid. It is a colorless liquid. It is obtained by condensaton of methanesulfonic acid with methanethiol . [ 1 ]
It has a role as a human metabolite. It is found in cytoplasm and extracellular fluid . It has been reported in Brassica oleracea (wild cabbage), Brassica family, Euglena gracilis , Trypanosoma brucei and Allium cepa (onion family). [ 1 ]
S -Methyl methanethiosulfonate is used as a flavoring agent. [ 1 ] It has a sulfurous, roasted and pungent odor and taste. [ 4 ]
S -Methyl methanethiosulfonate is a compound with a small molecule that reversibly blocks cysteine and other molecules containing sulfhydryl groups , enabling the study of enzyme activation and other protein functions. [ 1 ]
S -Methyl methanethiosulfonate causes skin irritation and corrosion. May cause serious eye iritation and serious eye damage. This compound is also a respiratory tract irritant. [ 1 ] | https://en.wikipedia.org/wiki/S-Methyl_methanethiosulfonate |
S -Methylcysteine is the amino acid with the nominal formula CH 3 SCH 2 CH(NH 2 )CO 2 H. It is the S-methylated derivative of cysteine . This amino acid occurs widely in plants, including many edible vegetables. [ 1 ]
S-Methylcysteine is not genetically coded, but it arises by post-translational methylation of cysteine. One pathway involves methyl transfer from alkylated DNA by zinc-cysteinate-containing repair enzymes. [ 2 ] [ 3 ]
S-Methylcysteine sulfoxide is an oxidized derivative of S-methylcysteine that is found in onions . [ 4 ]
Beyond its biological context, S-methylcysteine has been examined as a chelating agent . [ 5 ] | https://en.wikipedia.org/wiki/S-Methylcysteine |
S -Methylmethionine (SMM) is a derivative of methionine with the chemical formula ( CH 3 ) 2 S + CH 2 CH 2 CH(NH 3 + )CO 2 − . This cation is a naturally-occurring intermediate in many biosynthetic pathways owing to the sulfonium functional group . It is biosynthesized from L -methionine and S -adenosylmethionine by the enzyme methionine S -methyltransferase . S -methylmethionine is particularly abundant in plants, being more abundant than methionine. [ 2 ]
S -Methylmethionine is sometimes referred to as vitamin U , [ 3 ] but it is not considered a true vitamin . The term was coined in 1950 by Garnett Cheney for uncharacterized anti-ulcerogenic [ 4 ] factors in raw cabbage juice that may help speed healing of peptic ulcers .
S -Methylmethionine arises via the methylation of methionine by S -adenosyl methionine (SAM). The coproduct is S -adenosyl homocysteine . [ 2 ]
The biological roles of S -methylmethionine are not well understood. Speculated roles include methionine storage, use as a methyl donor, regulation of SAM. [ 2 ] A few plants use S -methylmethionine as a precursor to the osmolyte dimethylsulfoniopropionate (DMSP). Intermediates include dimethylsulfoniumpropylamine and dimethylsulfoniumpropionaldehyde. [ 5 ]
S -Methylmethionine is found in barley and is further created during the malting process. SMM can be subsequently converted to dimethyl sulfide (DMS) during the malt kilning process, causing an undesirable flavor. Lightly kilned malts such as pilsner or lager malts retain much of their SMM content while higher kilned malt such as pale ale malt has substantially more of the SMM converted to DMS in the malt. Darker kilned malts such as Munich malt have virtually no SMM content since most has been converted to DMS. Other crystal malts and roasted malts have no SMM content and often no DMS content since the kilning also drives that compound out of the malt. [ 6 ] [ 7 ] | https://en.wikipedia.org/wiki/S-Methylmethionine |
In organic chemistry , S -nitrosothiols , also known as thionitrites , are organic compounds or functional groups containing a nitroso group attached to the sulfur atom of a thiol . [ 1 ] S -Nitrosothiols have the general formula R−S−N=O , where R denotes an organic group.
S -Nitrosothiols have received much attention in biochemistry because they serve as donors of both the nitrosonium ion NO + and of nitric oxide and thus best rationalize the chemistry of NO-based signaling in living systems, especially related to vasodilation . [ 2 ] Red blood cells , for instance, carry an essential reservoir of S -nitrosohemoglobin and release S -nitrosothiols into the bloodstream under low-oxygen conditions, causing the blood vessels to dilate. [ 3 ]
Originally suggested by Ignarro to serve as intermediates in the action of organic nitrates, endogenous S -nitrosothiols were discovered by Stamler and colleagues ( S -nitrosoalbumin in plasma and S -nitrosoglutathione in airway lining fluid) and shown to represent a main source of NO bioactivity in vivo . More recently, S -nitrosothiols have been implicated as primary mediators of protein S -nitrosylation , the oxidative modification of cysteine thiol that provides ubiquitous regulation of protein function.
S -nitrosothiols are composed of small molecules, peptides and proteins. The addition of a nitroso group to a sulfur atom of an amino acid residue of a protein is known as S -nitrosylation or S - nitrosation . This is a reversible process and a major form of posttranslational modification of proteins. [ 4 ]
S -Nitrosylated proteins (SNO-proteins) serve to transmit nitric oxide (NO) bioactivity and to regulate protein function through enzymatic mechanisms analogous to phosphorylation and ubiquitinylation: SNO donors target specific amino acids motifs; post-translational modification leads to changes in protein activity, protein interactions, or subcellular location of target proteins; all major classes of proteins can undergo S -nitrosylation, which is mediated by enzymes that add (nitrosylases) and remove (denitrosylases) SNO from proteins, respectively. Accordingly, nitric oxide synthase (NOS) activity does not directly lead to SNO formation, but rather requires an additional class of enzymes (SNO synthases), which catalyze denovo S -nitrosylation. NOSs ultimately target specific Cys residues for S -nitrosylation through conjoint actions of SNO-synthases and transnitrosylases (transnitrosation reactions), which are involved in virtually all forms of cell signaling, ranging from regulation of ion channels and G-protein coupled reactions to receptor stimulation and activation of nuclear regulatory protein. [ 5 ] [ 6 ]
The prefix "S" indicates that the NO group is attached to sulfur. The S-N-O angle is near 114°, reflecting the influence of the lone pair of electrons on nitrogen. [ 7 ]
S -Nitrosothiols may arise from condensation from nitrous acid and a thiol: [ 8 ]
Other methods for their synthesis. They can be synthesized from N 2 O 3 and tert -butyl nitrite (tBuONO) are commonly used. [ 9 ] [ 10 ] [ 11 ] [ 12 ]
Once formed, these deeply colored compounds are often thermally unstable with respect to formation of the disulfide and nitric oxide: [ 13 ]
That equation reverses under irradiation. [ 14 ] Nitrosothiols also nitrosate amines in a similarly radical reaction: [ 13 ]
S -Nitrosothiols release nitrosonium ions ( NO + ) upon treatment with acids:
and they can transfer nitroso groups to other nucleophiles, including other thiols :
These reactions are, however, generally slow equilibria and require distillatory removal of the product to proceed. [ 15 ]
In the Saville reaction , mercury replaces the nitrosonium ion:
S -Nitrosothiols can be detected with UV-vis spectroscopy . | https://en.wikipedia.org/wiki/S-Nitrosothiol |
In biochemistry , S -nitrosylation is the covalent attachment of a nitric oxide group ( −NO ) to a cysteine thiol within a protein to form an S -nitrosothiol (SNO). S -Nitrosylation has diverse regulatory roles in bacteria , yeast and plants and in all mammalian cells . [ 1 ] It thus operates as a fundamental mechanism for cellular signaling across phylogeny and accounts for the large part of NO bioactivity .
S -Nitrosylation is precisely targeted, [ 2 ] reversible, [ 3 ] spatiotemporally restricted [ 4 ] [ 5 ] and necessary for a wide range of cellular responses, [ 6 ] including the prototypic example of red blood cell mediated autoregulation of blood flow that is essential for vertebrate life. [ 7 ] Although originally thought to involve multiple chemical routes in vivo , accumulating evidence suggests that S -nitrosylation depends on enzymatic activity, entailing three classes of enzymes ( S -nitrosylases) that operate in concert to conjugate NO to proteins, drawing analogy to ubiquitinylation . [ 8 ] Beside enzymatic activity, hydrophobicity and low pka values also play a key role in regulating the process. [ 6 ] S -Nitrosylation was first described by Stamler et al. and proposed as a general mechanism for control of protein function, including examples of both active and allosteric regulation of proteins by endogenous and exogenous sources of NO. [ 9 ] [ 10 ] [ 11 ] The redox -based chemical mechanisms for S -nitrosylation in biological systems were also described concomitantly. [ 12 ] Important examples of proteins whose activities were subsequently shown to be regulated by S -nitrosylation include the NMDA-type glutamate receptor in the brain. [ 13 ] [ 14 ] Aberrant S -nitrosylation following stimulation of the NMDA receptor would come to serve as a prototypic example of the involvement of S -nitrosylation in disease. [ 15 ] S -Nitrosylation similarly contributes to physiology and dysfunction of cardiac, airway and skeletal muscle and the immune system, reflecting wide-ranging functions in cells and tissues. [ 16 ] [ 17 ] [ 18 ] It is estimated that ~70% of the proteome is subject to S -nitrosylation and the majority of those sites are conserved. [ 19 ] S -Nitrosylation is also known to show up in mediating pathogenicity in Parkinson's disease systems. [ 20 ] S -Nitrosylation is thus established as ubiquitous in biology, having been demonstrated to occur in all phylogenetic kingdoms [ 21 ] and has been described as the prototypic redox-based signalling mechanism, [ 22 ]
The reverse of S -nitrosylation is denitrosylation, principally an enzymically controlled process. Multiple enzymes have been described to date, which fall into two main classes mediating denitrosylation of protein and low molecular weight SNOs, respectively. S -Nitrosoglutathione reductase (GSNOR) is exemplary of the low molecular weight class; it accelerates the decomposition of S -nitrosoglutathione (GSNO) and of SNO-proteins in equilibrium with GSNO. The enzyme is highly conserved from bacteria to humans. [ 23 ] Thioredoxin (Trx)-related proteins, including Trx1 and 2 in mammals, catalyze the direct denitrosylation of S -nitrosoproteins [ 24 ] [ 25 ] [ 26 ] (in addition to their role in transnitrosylation [ 27 ] ). Aberrant S -nitrosylation (and denitrosylation) has been implicated in multiple diseases, including heart disease, [ 18 ] cancer and asthma [ 28 ] [ 29 ] [ 17 ] as well as neurological disorders, including stroke, [ 30 ] chronic degenerative diseases (e.g., Parkinson's and Alzheimer's disease) [ 31 ] [ 32 ] [ 33 ] and amyotrophic lateral sclerosis (ALS). [ 34 ]
Another interesting aspect of S -nitrosylation includes the protein protein transnitrosylation, which is the transfer of an NO moiety from a SNO to the free thiols in another protein. Thioredoxin (Txn), a protein disulfide oxidoreductase for the cytosol and caspase 3 are a good example where transnitrosylation is significant in regulating cell death. [ 6 ] Another example include, the structural changes in mammalian Hb to SNO-Hb under oxygen depleted conditions helps it to bind to AE1 (Anion Exchange, a membrane protein) and in turn gets transnitrosylated the later. [ 35 ] Cdk5 (a neuronal-specific kinase) is known get nitrosylated at cysteine 83 and 157 in different neurodegenerative diseases like AD. This SNO-Cdk5 in turn is nitrosylated Drp1, the nitrosylated form of which can be considered as a therapeutic target. [ 36 ] | https://en.wikipedia.org/wiki/S-Nitrosylation |
The S-Series of ILS specifications is a common denominator for a set of specifications associated to different integrated logistics support aspects. [ 1 ] Originally developed by AECMA (French acronym for the Association Européenne des Constructeurs de Matériel Aeronautique, later ASD), the S-Series suite of ILS specifications is managed currently jointly by multinational teams from the AeroSpace and Defence Industries Association of Europe (ASD) and Aerospace Industries Association (AIA) [ 2 ] reporting to the AIA/ASD ILS Council. The ILS Council established the term S-Series (of) ILS specifications as the common denominator for all its specifications, and this term was consolidated with the publication of SX000i . [ 3 ]
The specifications encompassing the S-Series of ILS specifications are as follows:
The encoding of the specifications is inspired by the Dewey Decimal Classification (DDC) of human knowledge. Transversal specifications are encoded with an "X" instead of a number, so as to represent the "10" used in Roman numerals . The initial "S" stands for specification, and the last letter indicates a keyword within the title, as highlighted in the list above. Exceptions to this rule are S1000D (where the "D" stands for documentation ) and the specifications ending in "X", which represents "E x change". Though all letters are upper case, SX000i has a lower case ending letter for improved readability and to prevent confusion with an "l" in certain fonts.
Though strictly speaking it is not one of the S-Series specifications, ASD-STE100 is often associated to them because of its common origin with the S-Series of ILS specifications.
The S-Series of ILS specifications have in the past years made a significant effort to be interoperable, as this was not always necessarily true in the past. In that context, SX000i defines the common ILS process to which all the specifications will adhere, and SX002D defines a common data model that binds the data models of the different specifications together. This integration has ensured that the specifications have been included in the ASD Strategic Standardization Group (SSG) Radar Chart [ 4 ] as adopted.
In order to maintain the future interoperability of the specifications, SX000i establishes in its chapter 4 the governance of the S-Series ILS specifications and a common change process. A common unified S-Series ILS Specifications commenting tool was also established. [ 5 ]
The S-Series of ILS specifications are also involved in the development of the new ISO 10303-239 (AP239) PLCS Edition 3 project, [ 6 ] so as to integrate with the ISO 10303 STEP architecture and non-support domains such as Engineering or Manufacturing. The representatives of the S-Series in the AP239 Edition 3 project are members of the Data Modeling and Exchange Working Group (DMEWG), which is responsible for the development of SX001G, SX002D, SX003X, SX004G and SX005G. [ 7 ] | https://en.wikipedia.org/wiki/S-Series_of_ILS_specifications |
In nuclear physics , the astrophysical S -factor S ( E ) is a rescaling of a nuclear reaction 's total cross section σ ( E ) to account for the Coulomb repulsion between the charged reactants. It determines the rates of nuclear fusion reactions that occur in the cores of stars .
The quantity is defined as [ 1 ]
where E is the energy, σ is the cross section, η is the dimensionless Sommerfeld parameter :
Z 1 Z 2 e 2 is the product of the charges of the reactants, ϵ 0 {\displaystyle \epsilon _{0}} is the permittivity of free space , ℏ {\displaystyle \hbar } is the reduced Planck constant and v is the relative incident velocity .
The Coulomb barrier causes the cross section to have a strong exponential dependence on the center-of-mass energy E . The S -factor remedies this by factoring out the Coulomb component of the cross section. | https://en.wikipedia.org/wiki/S-factor |
S -matrix theory was a proposal for replacing local quantum field theory as the basic principle of elementary particle physics .
It avoided the notion of space and time by replacing it with abstract mathematical properties of the S -matrix . In S -matrix theory, the S -matrix relates the infinite past to the infinite future in one step, without being decomposable into intermediate steps corresponding to time-slices.
This program was very influential in the 1960s, because it was a plausible substitute for quantum field theory , which was plagued with the zero interaction phenomenon at strong coupling. Applied to the strong interaction, it led to the development of string theory .
S -matrix theory was largely abandoned by physicists in the 1970s, as quantum chromodynamics was recognized to solve the problems of strong interactions within the framework of field theory. But in the guise of string theory, S -matrix theory is still a popular approach to the problem of quantum gravity.
The S -matrix theory is related to the holographic principle and the AdS/CFT correspondence by a flat space limit. The analog of the S -matrix relations in AdS space is the boundary conformal theory. [ 1 ]
The most lasting legacy of the theory is string theory . Other notable achievements are the Froissart bound , and the prediction of the pomeron .
S -matrix theory was proposed as a principle of particle interactions by Werner Heisenberg in 1943, [ 2 ] following John Archibald Wheeler 's 1937 introduction of the S -matrix. [ 3 ]
It was developed heavily by Geoffrey Chew , Steven Frautschi , Stanley Mandelstam , Vladimir Gribov , and Tullio Regge . Some aspects of the theory were promoted by Lev Landau in the Soviet Union, and by Murray Gell-Mann in the United States.
The basic principles are:
The basic analyticity principles were also called analyticity of the first kind , and they were never fully enumerated, but they include
These principles were to replace the notion of microscopic causality in field theory, the idea that field operators exist at each spacetime point, and that spacelike separated operators commute with one another.
The basic principles were too general to apply directly, because they are satisfied automatically by any field theory. So to apply to the real world, additional principles were added.
The phenomenological way in which this was done was by taking experimental data and using the dispersion relations to compute new limits. This led to the discovery of some particles, and to successful parameterizations of the interactions of pions and nucleons.
This path was mostly abandoned because the resulting equations, devoid of any space-time interpretation, were very difficult to understand and solve.
The principle behind the Regge theory hypothesis (also called analyticity of the second kind or the bootstrap principle ) is that all strongly interacting particles lie on Regge trajectories . This was considered the definitive sign that all the hadrons are composite particles, but within S -matrix theory, they are not thought of as being made up of elementary constituents.
The Regge theory hypothesis allowed for the construction of string theories, based on bootstrap principles. The additional assumption was the narrow resonance approximation , which started with stable particles on Regge trajectories, and added interaction loop by loop in a perturbation series.
String theory was given a Feynman path-integral interpretation a little while later. The path integral in this case is the analog of a sum over particle paths, not of a sum over field configurations. Feynman's original path integral formulation of field theory also had little need for local fields, since Feynman derived the propagators and interaction rules largely using Lorentz invariance and unitarity. | https://en.wikipedia.org/wiki/S-matrix_theory |
The S-procedure or S-lemma is a mathematical result that gives conditions under which a particular quadratic inequality is a consequence of another quadratic inequality. The S-procedure was developed independently in a number of different contexts [ 1 ] [ 2 ] and has applications in control theory , linear algebra and mathematical optimization .
Let F 1 and F 2 be symmetric matrices, g 1 and g 2 be vectors and h 1 and h 2 be real numbers. Assume that there is some x 0 such that the strict inequality x 0 T F 1 x 0 + 2 g 1 T x 0 + h 1 < 0 {\displaystyle x_{0}^{T}F_{1}x_{0}+2g_{1}^{T}x_{0}+h_{1}<0} holds. Then the implication
holds if and only if there exists some nonnegative number λ such that
is positive semidefinite . [ 3 ] | https://en.wikipedia.org/wiki/S-procedure |
The slow neutron-capture process , or s -process , is a series of reactions in nuclear astrophysics that occur in stars, particularly asymptotic giant branch stars . The s -process is responsible for the creation ( nucleosynthesis ) of approximately half the atomic nuclei heavier than iron .
In the s -process, a seed nucleus undergoes neutron capture to form an isotope with one higher atomic mass . If the new isotope is stable , a series of increases in mass can occur, but if it is unstable , then beta decay will occur, producing an element of the next higher atomic number . The process is slow (hence the name) in the sense that there is sufficient time for this radioactive decay to occur before another neutron is captured. A series of these reactions produces stable isotopes by moving along the valley of beta-decay stable isobars in the table of nuclides .
A range of elements and isotopes can be produced by the s -process, because of the intervention of alpha decay steps along the reaction chain. The relative abundances of elements and isotopes produced depends on the source of the neutrons and how their flux changes over time. Each branch of the s -process reaction chain eventually terminates at a cycle involving lead , bismuth , and polonium .
The s -process contrasts with the r -process , in which successive neutron captures are rapid : they happen more quickly than the beta decay can occur. The r -process dominates in environments with higher fluxes of free neutrons ; it produces heavier elements and more neutron-rich isotopes than the s -process. Together the two processes account for most of the relative abundance of chemical elements heavier than iron.
The s -process was seen to be needed from the relative abundances of isotopes of heavy elements and from a newly published table of abundances by Hans Suess and Harold Urey in 1956. [ 1 ] Among other things, these data showed abundance peaks for strontium , barium , and lead , which, according to quantum mechanics and the nuclear shell model , are particularly stable nuclei, much like the noble gases are chemically inert . This implied that some abundant nuclei must be created by slow neutron capture , and it was only a matter of determining how other nuclei could be accounted for by such a process. A table apportioning the heavy isotopes between s -process and r -process was published in the famous B 2 FH review paper in 1957. [ 2 ] There it was also argued that the s -process occurs in red giant stars. In a particularly illustrative case, the element technetium , whose longest half-life is 4.2 million years, had been discovered in s-, M-, and N-type stars in 1952 [ 3 ] [ 4 ] by Paul W. Merrill . [ 5 ] [ 6 ] Since these stars were thought to be billions of years old, the presence of technetium in their outer atmospheres was taken as evidence of its recent creation there, probably unconnected with the nuclear fusion in the deep interior of the star that provides its power.
A calculable model for creating the heavy isotopes from iron seed nuclei in a time-dependent manner was not provided until 1961. [ 7 ] That work showed that the large overabundances of barium observed by astronomers in certain red-giant stars could be created from iron seed nuclei if the total neutron flux (number of neutrons per unit area) was appropriate. It also showed that no one single value for neutron flux could account for the observed s -process abundances, but that a wide range is required. The numbers of iron seed nuclei that were exposed to a given flux must decrease as the flux becomes stronger. This work also showed that the curve of the product of neutron-capture cross section times abundance is not a smoothly falling curve, as B 2 FH had sketched, but rather has a ledge-precipice structure . A series of papers [ 8 ] [ 9 ] [ 10 ] [ 11 ] [ 12 ] [ 13 ] in the 1970s by Donald D. Clayton utilizing an exponentially declining neutron flux as a function of the number of iron seed exposed became the standard model of the s -process and remained so until the details of AGB-star nucleosynthesis became sufficiently advanced that they became a standard model for s -process element formation based on stellar structure models. Important series of measurements of neutron-capture cross sections were reported from Oak Ridge National Lab in 1965 [ 14 ] and by Karlsruhe Nuclear Physics Center in 1982 [ 15 ] and subsequently, these placed the s -process on the firm quantitative basis that it enjoys today. [ citation needed ]
The s -process is believed to occur mostly in asymptotic giant branch stars, seeded by iron nuclei left by a supernova during a previous generation of stars. In contrast to the r -process which is believed to occur over time scales of seconds in explosive environments, the s -process is believed to occur over time scales of thousands of years, passing decades between neutron captures. The extent to which the s -process moves up the elements in the chart of isotopes to higher mass numbers is essentially determined by the degree to which the star in question is able to produce neutrons . The quantitative yield is also proportional to the amount of iron in the star's initial abundance distribution. Iron is the "starting material" (or seed) for this neutron capture-beta minus decay sequence of synthesizing new elements. [ 16 ]
The main neutron source reactions are:
One distinguishes the main and the weak s -process component. The main component produces heavy elements beyond Sr and Y , and up to Pb in the lowest metallicity stars. The production sites of the main component are low-mass asymptotic giant branch stars. [ 17 ] The main component relies on the 13 C neutron source above. [ 18 ] The weak component of the s -process, on the other hand, synthesizes s -process isotopes of elements from iron group seed nuclei to 58 Fe on up to Sr and Y, and takes place at the end of helium - and carbon-burning in massive stars. It employs primarily the 22 Ne neutron source. These stars will become supernovae at their demise and spew those s -process isotopes into interstellar gas.
The s -process is sometimes approximated over a small mass region using the so-called "local approximation", by which the ratio of abundances is inversely proportional to the ratio of neutron-capture cross-sections for nearby isotopes on the s -process path. This approximation is – as the name indicates – only valid locally, meaning for isotopes of nearby mass numbers, but it is invalid at magic numbers where the ledge-precipice structure dominates.
Because of the relatively low neutron fluxes expected to occur during the s -process (on the order of 10 5 to 10 11 neutrons per cm 2 per second), this process does not have the ability to produce any of the heavy radioactive isotopes such as thorium or uranium . The cycle that terminates the s -process is:
209 Bi captures a neutron, producing 210 Bi , which decays to 210 Po by β − decay . 210 Po in turn decays to 206 Pb by α decay :
206 Pb then captures three neutrons, producing 209 Pb , which decays to 209 Bi by β − decay, restarting the cycle:
The net result of this cycle therefore is that 4 neutrons are converted into one alpha particle , two electrons , two anti-electron neutrinos and gamma radiation :
The process thus terminates in bismuth, the heaviest "stable" element, and polonium, the first non-primordial element after bismuth. Bismuth is actually slightly radioactive, but with a half-life so long—a billion times the present age of the universe—that it is effectively stable over the lifetime of any existing star. Polonium-210 , however, decays with a half-life of 138 days to stable lead-206 .
Stardust is one component of cosmic dust . Stardust is individual solid grains that condensed during mass loss from various long-dead stars. Stardust existed throughout interstellar gas before the birth of the Solar System and was trapped in meteorites when they assembled from interstellar matter contained in the planetary accretion disk in early Solar System. Today they are found in meteorites, where they have been preserved. Meteoriticists habitually refer to them as presolar grains . The s -process enriched grains are mostly silicon carbide (SiC). The origin of these grains is demonstrated by laboratory measurements of extremely unusual isotopic abundance ratios within the grain. First experimental detection of s -process xenon isotopes was made in 1978, [ 19 ] confirming earlier predictions that s -process isotopes would be enriched, nearly pure, in stardust from red giant stars. [ 20 ] These discoveries launched new insight into astrophysics and into the origin of meteorites in the Solar System. [ 21 ] Silicon carbide (SiC) grains condense in the atmospheres of AGB stars and thus trap isotopic abundance ratios as they existed in that star. Because the AGB stars are the main site of the s -process in the galaxy, the heavy elements in the SiC grains contain almost pure s -process isotopes in elements heavier than iron. This fact has been demonstrated repeatedly by sputtering-ion mass spectrometer studies of these stardust presolar grains . [ 21 ] Several surprising results have shown that within them the ratio of s -process and r -process abundances is somewhat different from that which was previously assumed. It has also been shown with trapped isotopes of krypton and xenon that the s -process abundances in the AGB-star atmospheres changed with time or from star to star, presumably with the strength of neutron flux in that star or perhaps the temperature. This is a frontier of s -process studies in the 2000s. | https://en.wikipedia.org/wiki/S-process |
S.Pellegrino ( Italian pronunciation: [sampelleˈɡriːno] ) is an Italian natural mineral water brand, owned by the company Sanpellegrino S.p.A , part of Swiss company Nestlé since 1997. The principal production plant is located in San Pellegrino Terme in the Province of Bergamo, Lombardy , Italy. Its products are exported worldwide.
Sanpellegrino S.p.A. was founded in 1899, [ 2 ] and is based in Milan, Italy. [ 3 ]
On 20 April 1970, the company changed its name from Società Anonima Delle Terme di S.Pellegrino to Sanpellegrino S.p.A. [ 4 ]
In 1997, Sanpellegrino S.p.A. was bought by Perrier Vittel SA, a division of Nestlé which also owns the Perrier and Vittel bottled water brands. [ 5 ]
Paolo Luni, who joined the company as a consultant, then became General Manager and eventually CEO, left the company in 1999 after having inaugurated the Sanpellegrino Centennial celebrations, which took place in Teatro La Scala in Milan. [ 6 ]
The Sanpellegrino Company has ten production sites in Italy [ 7 ] including its headquarters, and more than 1,850 people work for the company. It also manages other brands such as Vera, Levissima and Acqua Panna . The revenue for 2016 was €895 million, [ 8 ] about €96 million less than the previous year. [ 9 ] More than 30,000 bottles of water are produced every hour in the San Pellegrino plant. [ 10 ] The bottles are then sorted to be exported to major countries around the world.
In 2005, five hundred million bottles were sold globally. In 2017, that number had increased to one billion bottles. [ 11 ]
S.Pellegrino mineral water is produced in San Pellegrino Terme . The water may originate from a layer of rock 400 metres (1,300 ft) below the surface, where it is mineralized from contact with limestone and volcanic rocks . The springs are located at the foot of a dolomite mountain wall which favours the formation and replenishment of a mineral water basin. The water then seeps to depths of over 700 m (2,300 ft) and flows underground to a distant aquifer .
The carbonation is then added during the production process as the spring itself is not naturally carbonated. The soft drinks do not use the same mineral water, rather it is produced using filtered local water to produce a consistent flavor.
S.Pellegrino mineral water has been produced for over 620 years. [ 12 ] In 1395, the town borders of San Pellegrino were drawn, marking the start of its water industry . Leonardo da Vinci is said to have visited the town in 1509 to sample and examine the town's miraculous water, later writing a treatise on water. [ 12 ]
Analysis shows that the water is strikingly similar to the samples taken in 1782, the first year such analysis took place. In fact, doctors from Northern Italy in the 13th century used to suggest that their patients go to the Val Brembana spring for treatment. [ 13 ] Over the years, its therapeutic properties attracted many visitors, and, at the beginning of 1900, San Pellegrino Terme became a mineral spa holiday resort with a casino, thermal baths and a hotel. [ 14 ]
In 1794, a treatise mentioned S.Pellegrino water as a treatment method for kidney stone disease . [ 15 ] In 1839, S.Pellegrino water was recommended for people affected with kidney diseases and urinary tract infection . [ 16 ]
In 1760, Pellegrino Foppoli built a bathhouse where visitors had to pay a fee to use the indoor facilities. [ 17 ] In 1803, Foppoli's descendants sold the bathhouse to Giovanni Pesenti who wanted to construct a larger building. [ 18 ] The town council feared that this project would prevent visitors from free use of the spring. For this reason, they filed a complaint with the prefect which led Ester Pesenti and Lorenzo Palazzolo to sign an agreement in 1831. They decided that the 24 unit spring would be divided into two. So that, 17 units were given to Pesenti and Palazzolo and 7 units to San Pellegrino Terme town council.
In 1834, the flood of the Brembo, the river that crosses San Pellegrino Terme, caused serious damage in the valley. [ 19 ] Since the restoration required huge expenses, in 1837, the town leased Pesenti and Palazzolo its share of the water for 12 years. In 1841, Ester Pesenti requested an authorization to continue to expand the bathhouse. [ 20 ]
One year later, another flood hit the valley and San Pellegrino Terme sold three-quarters of its shares to Pesenti. Since the water had always been connected to the territory, they agreed to give the remaining quarter of the shares to the residents of the town who still can use an external tap free of charge. [ 21 ] The construction work finished in 1846.
When Queen Margherita visited the town in 1905, [ 22 ] many articles appeared on the Giornale di San Pellegrino, in which it was illustrated that the bottled mineral water was sold in the main Italian cities, in many cities around Europe, as well as in Cairo , Tangiers , Shanghai , Calcutta , Sydney , Brazil, Peru, and the United States. At that time, one case of 50 bottles cost 26 Italian lire , while a case of 24 bottles cost 14 Italian lire. At the beginning of the 20th century, carbon dioxide was added to S.Pellegrino to prevent the development of bacteria, especially during long overseas travels. It is still taken from sources in Tuscany and sent to San Pellegrino Terme. [ 23 ]
The spa facilities were renovated, and in 1928, they were equipped with more modern tools for various diagnostic needs, such as the radioscopic and radiograph room and the microscopic and chemical analysis laboratory. [ 12 ] In addition, Granelli reorganized the bottling plant with new equipment, which moved up to a production capacity of 120,000 bottles a day. At the beginning, it was a handmade production, then it became gradually mechanized and was managed by an all female staff. The first machinery was introduced in 1930 and, since that moment, the amount produced has been increasing. Subsequently, the company began a packaging process for shipping to the recipient countries. [ 24 ]
In 1961, Sanpellegrino S.p.A. started to produce bottled mineral water and other beverages in the new San Pellegrino Terme factory. In 1932, the Aranciata orangeade variant was introduced. Containing S.Pellegrino as its primary ingredient, the soda added concentrated orange juice . Today, Sanpellegrino S.p.A. also produces various other flavors of carbonated beverages: Limonata ( lemonade ), Sanbittèr ( bitters ), Pompelmo ( grapefruit ), Aranciata Rossa ( blood orange ), and Chinò ( chinotto ).
In 1968, S.Pellegrino appeared on the front cover of the British Sunday newspaper The Observer . [ citation needed ]
During the Italian Occupation of Ethiopia production was curtailed in its entirety for the Italian military water needs. During this time they advocated for the policy changes Mussolini's government had been implementing. This increased revenue dramatically for several years, even after the occupation had faltered. Over the years, the bottling lines increased the production levels needed to satisfy the needs of a market which was becoming more and more sophisticated, and in 2012 a high speed PET bottling line was installed. [ 25 ]
The company built a new plant [ when? ] some kilometers beyond the previous one as the water production continued to grow. In the early 1970s, it was decided to no longer use mineral water in the production of soft drinks, and to substitute it with spring water which was treated with particular equipment. [ citation needed ]
In May 2014, Sanpellegrino S.p.A. released two new flavors of their Sparkling Fruit Beverages. The new flavors were Melograno e Arancia (Pomegranate and Orange) and Clementina (Clementine). They were announced through an installation at Eataly's La Scuola Grande in New York where large cans of the new soda flavors were constructed out of flowers. In Italy, S.Pellegrino is available in 1.5 L bottles for about one euro, the same for their Aranciata in most stores. Competitive orange drinks can cost even less. If artificial sweeteners are used, the price is about half that of the sugared varieties. [ citation needed ]
The bottles' packaging has maintained the original references to its territory and its first productions. [ 26 ] The products on the market can be divided into two categories: glass and PET . [ 27 ]
The shape of the glass bottles has remained the same since its origin in 1899. The model is called Vichy because at that time San Pellegrino Terme was known as "the Italian Vichy", [ 28 ] and it is characterized by the elongated shape of the bottle. The red star was a symbol of high quality products exported from Italy between the 1800s and the 1900s. [ 29 ] On the neck of the bottle there is a representation of the Casino, above the date of foundation of the brand and the company. The label features an elaborate white and blue watermark which recalls the Belle Epoque style.
The PET line has the same shape of the glass bottles. The production started at the end of the 1990s with the aim of maintaining the same perlage and effervescence of the glass line. At the beginning, only the 50 centiliters size was produced, but since 2006, the production of the 33, 75 and 100 centilitre bottles were added to the original one. [ 30 ]
Different versions of the label were created for collaborations, partnerships and international events.
In 2010, 2011 and 2013 the project "S.Pellegrino Meets Italian Talents" was meant to create collaborations with Italians known on an international level as a symbol of Italy. These collaborations include Missoni , [ 31 ] [ 32 ] Bulgari [ 33 ] and a tribute to Luciano Pavarotti . [ 34 ]
In 2007, the German consumer television program Markt reported that S.Pellegrino contains uranium . [ citation needed ] Nestlé was informed about this and responded [ citation needed ] that uranium was common in both bottled and tap water and that the 0.0070 mg /l found in their product was below the 0.03 mg/L threshold established by various governments and food health organizations. [ 12 ] [ 35 ]
S.Pellegrino is not suitable for infants under 12 weeks of age, [ 36 ] because their gastrointestinal tract and urinary system is immature and cannot withstand highly mineralized water. [ 37 ] | https://en.wikipedia.org/wiki/S.Pellegrino |
Søren Peter Lauritz Sørensen (9 January 1868 – 12 February 1939) was a Danish chemist , known for the introduction of the concept of pH , a scale for measuring acidity and alkalinity .
Sørensen was born in Havrebjerg in 1868 as the son of a farmer. He began his studies at the University of Copenhagen at the age of 18. He wanted to make a career in medicine, but under the influence of chemist Sophus Mads Jørgensen decided to change to chemistry. [ 1 ]
While studying for his doctorate he worked as assistant in chemistry at the laboratory of the Technical University of Denmark , assisted in a geological survey of Denmark, and also worked as a consultant for the Royal Navy Dockyard . [ 1 ]
Sørensen was married twice. His second wife was Margrethe Høyrup Sørensen, who collaborated with him in his studies. [ 1 ]
From 1901 to 1938, Sørensen was head of the prestigious Carlsberg Laboratory , Copenhagen . [ 2 ] While working at the Carlsberg Laboratory he studied the effect of ion concentration on proteins [ 3 ] and, because the concentration of hydrogen ions was particularly important, he introduced the pH -scale as a simple way of expressing it in 1909. [ 4 ] The article in which he introduced the scale (using the notation p H {\displaystyle p_{\mathrm {H} }} ) was published in French and Danish as well as in German [ 5 ] described two methods for measuring acidity which Sørensen and his students had refined. [ 6 ] The first method was based on electrodes, whereas the second involved comparing the colours of samples and a preselected set of indicators. (Sørensen, 1909). | https://en.wikipedia.org/wiki/S._P._L._Sørensen |
S/2015 (136472) 1 , unofficially nicknamed MK2 by the discovery team, [ 2 ] is the only known moon of the trans-Neptunian dwarf planet Makemake . [ 1 ] [ 4 ] It is estimated to be 175 km (110 mi) in diameter and has a semi-major axis of at least 21,000 km (13,000 mi) from Makemake. [ 1 ] Its orbital period is at least 12 days if it has a circular orbit. [ 1 ] [ 5 ] [ 4 ] Observations leading to its discovery occurred in April 2015, using the Hubble Space Telescope 's Wide Field Camera 3 , and its discovery was announced on 26 April 2016. [ 2 ]
S/2015 (136472) 1 is extremely faint, with an apparent magnitude of 25 in visible light . [ 3 ] The satellite is 1,300 times fainter than Makemake, which corresponds to a magnitude difference of 7.80 between it and Makemake. [ 6 ] [ 1 ] : 3
Prior to the discovery S/2015 (136472) 1, measurements of Makemake's far-infrared thermal emission by the Spitzer and Herschel space telescopes showed that the dwarf planet emits more thermal radiation than expected for its size and brightness in visible light. [ 4 ] This led astronomers to suspect that Makemake must have extra dark surface area that is contributing to this excess thermal emission. [ 1 ] : 3 Makemake does not exhibit significant variations in brightness as it rotates, which leaves the possibilities that some of this dark surface area may either be uniformly distributed on Makemake's surface or is located on satellites orbiting Makemake. [ 4 ] [ 1 ] : 3 [ 7 ] : 6 The discovery of S/2015 (136472) 1 lends credibility to the hypothesis that Makemake's excess thermal emission largely comes from satellites with dark surfaces. [ 7 ] : 6
Assuming S/2015 (136472) 1 has a uniformly dark surface, the satellite has a geometric albedo or visible light reflectivity of 2–4%, which makes it as dark as charcoal . [ 1 ] : 3–4 [ 6 ] The satellite is exceptionally dark compared to Makemake's geometric albedo of 82%; this may be because the satellite's gravity is too weak to hold on to bright, volatile ices as they sublimate off the satellite's surface into space. [ 1 ] : 4 [ 6 ] S/2015 (136472) 1 is estimated to have a diameter between 175–250 km (109–155 mi), based on its geometric albedo and brightness in visible light. [ a ] Within this range, S/2015 (136472) 1's diameter is most likely 175 km (109 mi) for a geometric albedo of 4%. [ 1 ] : 4 If S/2015 (136472) 1 has the same density as Makemake, then it would contribute less than 0.2% of the total system mass. [ 1 ] : 4
S/2015 (136472) 1 alone cannot be responsible for all of Makemake's excess thermal emission because its diameter and surface area only accounts for 20–30% of the total dark surface area. [ 1 ] : 3 [ b ] Even the maximum possible diameter of S/2015 (136472) 1 is too small to account for all of this dark surface area. [ 1 ] : 3 Furthermore, S/2015 (136472) 1 is too small to have tidally slowed down Makemake to its current rotation period of 22.8 hours. [ 7 ] : 6 These details indicate that there may be another large, undiscovered satellite orbiting Makemake. A satellite that is responsible for Makemake's slow rotation would have to be 3–5% of Makemake's mass and 400–550 km (250–340 mi) in diameter, which would be large enough to account for the remaining dark surface area. This undiscovered satellite would have to be closely orbiting Makemake at a distance of 3,000–5,000 km (1,900–3,100 mi), which would make it undetectable to current telescopes like Hubble. [ 7 ] : 6 It is possible that this undiscovered satellite has an irregular shape, which could account for most of Makemake's rotational brightness variability. [ 7 ] : 6
Alex Parker, the leader of the team that performed the analysis of the discovery images at the Southwest Research Institute , said that from the discovery images, S/2015 (136472) 1's orbit appears to be aligned edge-on to Earth-based observatories. [ 5 ] This would make it difficult to detect because it would be lost in Makemake's glare much of the time, which, along with its dark surface, would contribute to previous surveys failing to observe it. [ 1 ] Observations taken in 2018 and 2019 may be enough to determine whether the orbit is close to circular, which would suggest that S/2015 (136472) 1 was formed by an ancient impact event, or if it is significantly eccentric, which would suggest that it was captured. [ 6 ]
As of 2025 [update] , the satellite has no official name. [ 8 ] The designation S/2015 (136472) 1 is the satellite's provisional designation , with "S/" indicating satellite, "2015" being the satellite's year of discovery, and "1" being the satellite's order of discovery in that year. [ 9 ] "(136472)" is Makemake's minor-planet number . [ 10 ]
The nickname 'MK2' simply means object 2 in the Makemake system . A permanent name may be chosen from an associated figure in the mythology of Easter Island.
Solar System → Local Interstellar Cloud → Local Bubble → Gould Belt → Orion Arm → Milky Way → Milky Way subgroup → Local Group → Local Sheet → Virgo Supercluster → Laniakea Supercluster → Local Hole → Observable universe → Universe Each arrow ( → ) may be read as "within" or "part of". | https://en.wikipedia.org/wiki/S/2015_(136472)_1 |
S1909/A2840 is a bill that was passed by the New Jersey Legislature in December 2003, and signed into law by Governor James McGreevey on January 4, 2004, that permits human cloning for the purpose of developing and harvesting human stem cells . Specifically, it legalizes the process of cloning a human embryo, and implanting the clone into a womb, provided that the clone is then aborted and used for medical research. The legislation was sponsored by Senators Richard Codey (D-Essex) and Barbara Buono , and Assembly members Neil M. Cohen (D-Union), John F. McKeon , Mims Hackett (D-Essex), and Joan M. Quigley (D-Hudson). The enactment of this law will enable researchers to find cures for debilitating and deadly diseases.
Supporters of the legislation hailed it as promoting medical progress through science, giving hope for the development of treatments for debilitating diseases such as Parkinson's disease, Alzheimer's disease , cancer , and diabetes . Assemblyman Neil Cohen lauded it as "not the most significant law we'll write this session—but this century." Paralyzed actor Christopher Reeve , who believed that such legislation may hasten the development of methods to reverse paralysis, testified in support of the bill.
However, Congressmen Chris Smith , Mike Ferguson , and Scott Garrett assailed it, saying, "This legislation will launch New Jersey blindly into the vanguard of terrible human-rights violations and grisly human experimentation." They also claim that, in practice, once a clone is developing in a womb, there is nothing that will prevent it from leading to "the world's first human clone being born and starting a horrible new era of human history." New Jersey's Catholic bishops condemned the newly legalized process as violating "a central tenet of all civilized codes on human experimentation beginning with the Nuremberg Code ...[It approves] doing deadly harm to a member of the human species solely for the sake of potential benefit to others."
SCNT is currently legal for research purposes in the United Kingdom, having been incorporated into the 1990 Human Fertilisation and Embryology Act in 2001. Permission must be obtained from the Human Fertilisation and Embryology Authority in order to perform or attempt SCNT.
In the United States, the practice remains legal, as it has not been addressed by federal law.
In 2005, the United Nations adopted a proposal submitted by Costa Rica, calling on member states to "prohibit all forms of human cloning inasmuch as they are incompatible with human dignity and the protection of human life." This phrase may include SCNT, depending on interpretation.
The Council of Europe's Convention on Human Rights and Biomedicine and its Additional Protocol to the Convention for the Protection of Human Rights and Dignity of the Human Being with regard to the Application of Biology and Medicine, on the Prohibition of Cloning Human Being appear to ban SCNT. Of the council's 45 member states, the convention has been signed by 31 and ratified by 18. The Additional Protocol has been signed by 29 member nations and ratified by 14. | https://en.wikipedia.org/wiki/S1909/A2840 |
Asparagusic acid is an organosulfur compound with the molecular formula C 4 H 6 O 2 S 2 and systematically named 1,2-dithiolane-4-carboxylic acid. The molecule consists of a heterocyclic disulfide functional group (a 1,2- dithiolane ) with a carboxylic acid side chain. It is found in asparagus and is believed to be the metabolic precursor to odorous sulfur compounds responsible for the distinctive smell of urine which has long been associated with eating asparagus. [ 3 ] [ 4 ]
The material was originally isolated from an aqueous extract of Asparagus officinalis , a spring vegetable . [ 5 ] It is a derivative of the cyclic disulfide organic compound 1,2-dithiolane with a carboxylic acid functional group bound to carbon-4 of the heterocycle . Biosynthetic studies revealed that asparagusic acid is derived from isobutyric acid . [ 6 ] Asparagusic acid is a colorless solid with a melting point of 75.7–76.5 °C, [ 2 ] higher than that of the corresponding dithiol: dihydroasparagusic acid (or γ,γ-dimercaptoisobutyric acid), at 59.5–60.5 °C. [ 7 ]
A convenient synthesis of asparagusic acid has been developed from a commercially available diethyl malonate derivative starting material, improving on the prior method of Jansen. [ 5 ] Diethyl bis(hydroxymethyl)malonate is treated with hydroiodic acid to yield β,β'-diiodoisobutyric acid after decarboxylation and ester hydrolysis (with removal of volatile ethanol and carbon dioxide ). Dihydroasparagusic acid, the reduced ( dithiol ) form of asparagusic acid, is produced by sequential reaction with sodium trithiocarbonate (Na 2 CS 3 ) and sulfuric acid ; subsequent oxidation with hot dimethyl sulfoxide yields asparagusic acid. [ 1 ]
Observations that eating asparagus results in a detectable change in the odour of urine have been recorded over time. In 1702, Louis Lémery noted "a powerful and disagreeable smell in the urine", [ 8 ] whilst John Arbuthnot noted that "asparagus ... affects the urine with a foetid smell." [ 9 ] [ 10 ] Benjamin Franklin described the odour as "disagreable", [ 11 ] whilst Marcel Proust claimed that asparagus "transforms my chamber-pot into a flask of perfume." [ 10 ] [ 12 ] As early as 1891, Marceli Nencki had attributed the smell to methanethiol . [ 13 ] [ 14 ] The odour is attributed to a mixture of sulfur-containing metabolites of asparagusic acid. [ 3 ] [ 4 ] [ 15 ] [ 16 ]
The origin of asparagus urine is asparagusic acid, a substance unique to this vegetable. [ 17 ] [ 18 ] Most studies of the compounds responsible for the odour of asparagus urine have correlated the appearance of the compounds above with asparagus consumption; they appear as little as 15 minutes after consumption. [ 10 ] However, this does not provide information on the biochemical processes that lead to their formation.
Asparagusic acid and lipoic acid are similar in that both possess a 1,2-dithiolane ring with a carboxylic acid tethered to it; indeed, it has been reported that asparagusic acid can substitute for lipoic acid in α-keto-acid oxidation systems such as the citric acid cycle . [ 18 ] The ( R )-(+)- enantiomer of α-lipoic acid is a cofactor in the pyruvate dehydrogenase complex and is essential for aerobic metabolism . The degradation pathway of lipoic acid has been well studied and includes evidence of reduction of the disulfide bridge, S -methylation, and oxidation to produce sulfoxides. [ 19 ] Similar transformations of asparagusic acid would lead to metabolites like this detected in asparagus urine. Synthetic work has confirmed the relative ease of oxidation of asparagusic acid to yield S -oxides of the dithiolane ring. [ 1 ] The rate of degradation appears highly variably between subjects; the typical half-life for odour disappearance is around 4 h with a between subject variability of 43.4%. [ 20 ]
In the small minority of people who do not produce these metabolites after consuming asparagus, the reason may be as simple as asparagusic acid not being taken into the body from the digestive tract [ 3 ] or that these individuals metabolise it in such a way as to minimise the release of volatile sulfur-containing products. [ 10 ] | https://en.wikipedia.org/wiki/S2(CH2)2CHCO2H |
Disulfur dibromide is the inorganic compound with the formula S 2 Br 2 . It is a yellow-brown liquid that fumes in air. It is prepared by direct combination of the elements and purified by vacuum distillation. [ 3 ] Higher yields can be obtained from disulfur dichloride and 50% aqueous hydrobromic acid , but the product must be promptly removed from water, lest it hydrolyze. [ 1 ] The compound has no particular application, [ citation needed ] unlike the related sulfur compound disulfur dichloride , although acidic alcoholysis is "an excellent synthesis of alkyl bromides ." [ 1 ]
The molecular structure is Br−S−S−Br , akin to that of disulfur dichloride ( S 2 Cl 2 ). According to electron diffraction measurements, the angle between the Br a −S−S and S−S−Br b planes is 84° and the Br−S−S angle is 107°. The S−S distance is 198.0 pm , circa 5.0 pm shorter than for S 2 Cl 2 . [ 4 ] | https://en.wikipedia.org/wiki/S2Br2 |
Disulfur dichloride (or disulphur dichloride by the British English spelling) is the inorganic compound of sulfur and chlorine with the formula S 2 Cl 2 . [ 4 ] [ 5 ] [ 6 ] [ 7 ] It is an amber oily liquid.
Sometimes, this compound is incorrectly named sulfur monochloride (or sulphur monochloride by the British English spelling), the name implied by its empirical formula SCl.
S 2 Cl 2 has the structure implied by the formula Cl−S−S−Cl , wherein the dihedral angle between the Cl a −S−S and S−S−Cl b planes is 85.2°. This structure is referred to as gauche , and is akin to that for H 2 O 2 . A rare isomer of S 2 Cl 2 is S=SCl 2 (thiothionyl chloride); this isomer forms transiently when S 2 Cl 2 is exposed to UV-radiation (see thiosulfoxides ).
Disulfur dichloride is a yellow liquid that fumes in moist air due to reaction with water:
It is produced by partial chlorination of elemental sulfur . The reaction proceeds at usable rates at room temperature. In the laboratory, chlorine gas is led into a flask containing elemental sulfur. As disulfur dichloride is formed, the contents become a golden yellow liquid: [ 8 ]
Excess chlorine produces sulfur dichloride , which causes the liquid to become less yellow and more orange-red:
The reaction is reversible, and upon standing, SCl 2 releases chlorine to revert to the disulfur dichloride. Disulfur dichloride has the ability to dissolve large quantities of sulfur, which reflects in part the formation of dichloropolysulfanes :
Disulfur dichloride can be purified by distillation from excess elemental sulfur.
S 2 Cl 2 also arises from the chlorination of CS 2 as in the synthesis of thiophosgene or carbon tetrachloride .
S 2 Cl 2 hydrolyzes to sulfur dioxide and elemental sulfur . When treated with hydrogen sulfide , polysulfanes are formed as indicated in the following idealized formula:
It reacts with ammonia to give tetrasulfur tetranitride as well as heptasulfur imide ( S 7 NH ) and related S−N rings S 8− n (NH) n ( n = 2, 3). [ 9 ]
With primary and secondary alkoxide equivalents, it forms disulfoxylate esters:
In principle the subsequent addition of base should give sulfoxylate esters, but typically induces disproportionation to aldehydes and alcohols instead. [ 10 ]
S 2 Cl 2 has been used to introduce C−S bonds . In the presence of aluminium chloride ( AlCl 3 ), S 2 Cl 2 reacts with benzene to give diphenyl sulfide:
Anilines (1) react with S 2 Cl 2 in the presence of NaOH to give 1,2,3-benzodithiazolium chloride (2) ( Herz reaction ) which can be transformed into ortho -aminothiophenolates (3), these species are precursors to thioindigo dyes .
It is also used to prepare mustard gas via ethylene at 60 °C (the Levinstein process):
If the reaction is performed at a temperature under 30 °C, the sulfur stays in "pseudo-solution" and avoids the problems associated with the sulfur that is formed during the reaction.
Other uses of S 2 Cl 2 include the manufacture of sulfur dyes , insecticides , and synthetic rubbers . It is also used in cold vulcanization of rubbers , as a polymerization catalyst for vegetable oils and for hardening soft woods . [ 11 ]
S 2 Cl 2 can be used to produce bis(2-chloroethyl)sulfide S(CH 2 CH 2 Cl) 2 , known as the mustard gas: [ 11 ]
Consequently, it is listed in Schedule 3 of the Chemical Weapons Convention . Facilities that produce and/or process and/or consume scheduled chemicals may be subject to control, reporting mechanisms and inspection by the Organisation for the Prohibition of Chemical Weapons . | https://en.wikipedia.org/wiki/S2Cl2 |
Disulfur decafluoride is a chemical compound with the formula S 2 F 10 . It was discovered in 1934 by Denbigh and Whytlaw-Gray. [ 4 ] Each sulfur atom of the S 2 F 10 molecule is octahedral , and surrounded by five fluorine atoms [ 5 ] and one sulfur atom. The two sulfur atoms are connected by a single bond. In the S 2 F 10 molecule, the oxidation state of each sulfur atoms is +5, but their valency is 6 (they are hexavalent ). S 2 F 10 is highly toxic , with toxicity four times that of phosgene .
It is a colorless liquid with a burnt match smell similar to sulfur dioxide . [ 1 ]
Disulfur decafluoride is produced by photolysis of SF 5 Br : [ 6 ]
Disulfur decafluoride arises by the decomposition of sulfur hexafluoride . It is produced by the electrical decomposition of sulfur hexafluoride ( SF 6 )—an essentially inert insulator used in high voltage systems such as transmission lines , substations and switchgear . S 2 F 10 is also made during the production of SF 6 .
The S-S bond dissociation energy is 305 ± 21 kJ/mol, about 80 kJ/mol stronger than the S-S bond in diphenyldisulfide .
At temperatures above 150 °C, S 2 F 10 decomposes slowly ( disproportionation ) into SF 6 and SF 4 :
S 2 F 10 reacts with N 2 F 4 to give SF 5 NF 2 . It reacts with SO 2 to form SF 5 OSO 2 F in the presence of ultraviolet radiation.
In the presence of excess chlorine gas, S 2 F 10 reacts to form sulfur chloride pentafluoride ( SF 5 Cl ):
The analogous reaction with bromine is reversible and yields SF 5 Br . [ 7 ] The reversibility of this reaction can be used to synthesize S 2 F 10 from SF 5 Br . [ 8 ]
Ammonia is oxidised by S 2 F 10 into NSF 3 . [ 9 ]
S 2 F 10 was considered a potential chemical warfare pulmonary agent in World War II because it does not produce lacrimation or skin irritation, thus providing little warning of exposure.
Disulfur decafluoride is a colorless gas or liquid with a SO 2 -like odor. [ 10 ] It is about four times as poisonous as phosgene. Its toxicity is thought to be caused by its disproportionation in the lungs into SF 6 , which is inert, and SF 4 , which reacts with moisture to form sulfurous acid and hydrofluoric acid . [ 11 ] | https://en.wikipedia.org/wiki/S2F10 |
1,1,1,2-tetrafluorodisulfane , also known as 1,2-difluorodisulfane 1,1-difluoride or just difluorodisulfanedifluoride ( FSSF 3 ) is an unstable molecular compound of fluorine and sulfur . The molecule has a pair of sulfur atoms, with one fluorine atom on one sulfur, and three fluorine atoms on the other. It has the uncommon property that all the bond lengths are different. [ 3 ] The bond strength is not correlated with bond length but is inversely correlated with the force constant ( Badger's rule ). [ 3 ] The molecule can be considered as sulfur tetrafluoride in which a sulfur atom is inserted into a S-F bond. [ 3 ]
Atoms are labelled with the sulfur atom connected to three fluorine atoms as S hyp (for hypervalent) and S top . The fluorine atoms are labelled F top attached to S top , and on the hypervalent S atom: F cis , the closest F atom to F top , F trans the furthest away F atom from F top , and F eq [ 3 ]
Carlowitz first determined the structure in 1983. [ 3 ]
F eq is 90° from F trans , and 84° from F cis , and the torsion compared to F top is about 95°. [ 4 ]
The dimerization reaction 2SF 2 ⇌ FSSF 3 is reversible. [ 5 ] It also disproportionates: SF 2 + FSSF 3 → FSSF + SF 4 . [ 5 ] A side reaction also produces the intermediate F 3 SSSF 3 . [ 6 ] hydrogen fluoride catalyses disproportionation to sulfur and sulfur tetrafluoride by forming a reactive intermediate HSF molecule. [ 7 ] When FSSF 3 dissociates, the F cis atom forms a new bond to the S top atom, and the S-S bond breaks. [ 3 ] As a gas, at ambient and totally clean conditions, FSSF 3 decomposes with a half life of about 10 hours. Disproportionation to SSF 2 and SF 4 catalysed by metal fluorides can take place in under one second. However it is indefinitely stable at -196 °C. [ 4 ]
A symmetrical molecule F 2 SSF 2 is calculated to be 15.1 kcal/mol higher in energy than FSSF 3 . [ 3 ]
FSSF 3 is easily hydrolysed with water. [ 8 ]
FSSF 3 spontaneously reacts with oxygen gas to make thionyl fluoride , the only sulfur fluoride that does not need any assistance to do this. [ 8 ] FSSF 3 reacts with copper at high temperatures producing copper fluoride and copper sulfide. [ 8 ]
SF 3 SF can be made in the laboratory when low pressure (10 mm Hg) SCl 2 vapour is passed over potassium fluoride or mercuric fluoride heated to 150 °C. Byproducts include FSSF, SSF 2 , SF 4 , SF 3 SCl, and FSSCl. [ 8 ] SF 3 SCl can be removed from this mixture in a reaction with mercury. [ 8 ] Separation of the sulfur fluorides can be achieved by low temperature distillation. SF 3 SF distills just above -50 °C. [ 9 ]
SF 3 SF is also made in small amounts by reacting sulfur with silver fluoride , or photolysis of disulfur difluoride and SSF 2 . [ 8 ] The molecule is formed by the dimerization of sulfur difluoride . [ 3 ]
The nuclear magnetic resonance spectrum of FSSF 3 shows four bands, each of eight lines at -53.2, -5.7, 26.3 and 204.1 ppm. [ 5 ]
FSSF 3 is stable as a solid, as a liquid below -74 °C and dissolved in other sulfur fluoride liquids. [ 8 ] This is in contrast to SF 2 which is only stable as a dilute gas. [ 8 ]
Infrared vibration bands for FSSF 3 are at 810, 678, 530, 725, and 618(S-S) cm −1 . [ 8 ]
The related compound FSSSF 3 has a similar structure, but with an extra sulfur atom in the chain. Thiothionyltetrafluoride, S=SF 4 may exist as a gas. It is less energetically favourable to FSSF 3 by 37 kJ/mol, but has a high energy barrier of 267 kJ/mol. [ 10 ] However it may disproportionate rapidly to sulfur and sulfur tetrafluoride. [ 10 ] The other known sulfur fluorides are sulfur difluoride , sulfur tetrafluoride , sulfur hexafluoride , disulfur decafluoride , disulfur difluoride and thiothionyl fluoride , difluorotrisulfane , and difluorotetrasulfane . [ 10 ] The F top atom can be substituted with Cl to yield ClSSF 3 (2-chloro-1,1,1-trifluorodisulfane). [ 5 ] | https://en.wikipedia.org/wiki/S2F4 |
Disulfur dioxide , dimeric sulfur monoxide or SO dimer is an oxide of sulfur with the formula S 2 O 2 . [ 2 ] The solid is unstable with a lifetime of a few seconds at room temperature. [ 3 ]
Disulfur dioxide adopts a cis planar structure with C 2v symmetry . The S−O bond length is 145.8 pm, shorter than in sulfur monoxide . The S−S bond length is 202.45 pm and the O−S−S angle is 112.7°. S 2 O 2 has a dipole moment of 3.17 D. [ 4 ] It is an asymmetric top molecule. [ 1 ] [ 5 ]
The electronic ground state is a singlet, unlike disulfur or dioxygen . [ 6 ]
Sulfur monoxide (SO) converts to disulfur dioxide (S 2 O 2 ) spontaneously and reversibly. [ 4 ] So the substance can be generated by methods that produce sulfur monoxide. Disulfur dioxide has also been formed by an electric discharge in sulfur dioxide . [ 5 ] Another laboratory procedure is to react oxygen atoms with carbonyl sulfide or carbon disulfide vapour. [ 7 ]
Although most forms of elemental sulfur ( S 8 and other rings and chains) do not combine with SO 2 , atomic sulfur does so to form sulfur monoxide, which dimerizes: [ 8 ]
Disulfur dioxide is also produced upon a microwave discharge in sulfur dioxide diluted in helium . [ 9 ] At a pressure of 0.1 mmHg (13 Pa), five percent of the result is S 2 O 2 . [ 10 ]
Disulfur dioxide is formed transiently when hydrogen sulfide and oxygen undergo flash photolysis . [ 11 ]
A branched isomer isoelectronic to SO 3 , S=SO 2 , is believed to form during the thermal decomposition of cyclic vicinal alkyl thiosulfites . [ 12 ]
The ionization energy of disulfur dioxide is 9.93 ± 0.02 eV . [ 7 ]
Disulfur dioxide absorbs at 320–400 nm, as observed of the Venusian atmosphere , [ 13 ] and is believed to have contributed to the greenhouse effect on that planet. [ 14 ]
Although disulfur dioxide exists in equilibrium with sulfur monoxide , it also reacts with sulfur monoxide to form sulfur dioxide and disulfur monoxide . [ 9 ] [ 15 ]
Decomposition of S 2 O 2 proceeds via the following disproportionation reaction :
S 2 O 2 can be a ligand with transition metals. It binds in the η 2 -S–S position with both sulfur atoms linked to the metal atom. [ 16 ] This was first shown in 2003. The bis(trimethylphosphine) thiirane S -oxide complex of platinum , when heated in toluene at 110 °C loses ethylene , and forms a complex with S 2 O 2 : (Ph 3 P) 2 Pt(S 2 O 2 ). [ 17 ] Iridium atoms can also form a complex: cis -[(dppe) 2 IrS 2 ]Cl with sodium periodate oxidizes to [(dppe) 2 IrS 2 O] and then to [(dppe) 2 IrS 2 O 2 ], with dppe being 1,2-bis(diphenylphosphino)ethane . [ 18 ] [ 19 ] This substance has the S 2 O 2 in a cis position. The same conditions can make a trans complex, but this contains two separate SO radicals instead. The iridium complex can be decomposed with triphenylphosphine to form triphenylphosphine oxide and triphenylphosphine sulfide . [ 18 ]
The S 2 O − 2 radical anion has been observed in the gas phase. It may adopt a trigonal shape akin to SO 3 . [ 20 ]
There is some evidence that disulfur dioxide may be a small component in the atmosphere of Venus , and that it may substantially contribute of the planet's severe greenhouse effect . [ 13 ] It is not found in any substantive quantity in Earth's atmosphere. | https://en.wikipedia.org/wiki/S2O2 |
Thiosulfate ( IUPAC-recommended spelling ; sometimes thiosulphate in British English) is an oxyanion of sulfur with the chemical formula S 2 O 2− 3 . Thiosulfate also refers to the compounds containing this anion, which are the salts of thiosulfuric acid , such as sodium thiosulfate Na 2 S 2 O 3 and ammonium thiosulfate (NH 4 ) 2 S 2 O 3 . Thiosulfate salts occur naturally. Thiosulfate rapidly dechlorinates water, and is used to halt bleaching in the paper-making industry. Thiosulfate salts are mainly used for dyeing in textiles, and bleaching of natural substances. [ 2 ]
The thiosulfate ion is tetrahedral at the central S atom. The thiosulfate ion has C 3v symmetry. The external sulfur atom has a valence of 2 while the central sulfur atom has a valence of 6. The oxygen atoms have a valence of 2. The S-S distance of about 201 pm in sodium thiosulphate is appropriate for a single bond. The S-O distances are slightly shorter than the S-O distances in sulfate.
For many years, the oxidation states of the sulfur atoms in the thiosulfate ion were considered to be +6 as in sulfate and −2 as in sulfide for the central and terminal atoms, respectively. This view precluded the disproportionation reaction of thiosulfate into sulfate and sulfide as a redox mechanism for providing energy to bacteria under anaerobic conditions in sediments because there is no change in oxidation state for either S atom. However, XANES spectroscopy measurements have revealed that the charge densities of the sulfur atoms point towards +5 and −1 oxidation states for the central and terminal S atoms, respectively. This observation is consistent with the disproportionation of thiosulfate into sulfate and sulfide as a redox mechanism freeing up energy from microbial fermentation . [ 3 ] Yet another interpretation suggests an oxidation state of +4 for the central S atom and 0 for the terminal atom and an unusually long 'full' S=S double bond between the two.
Thiosulfate ion is produced by the reaction of sulfite ion with elemental sulfur, and by incomplete oxidation of sulfides (e.g. pyrite oxidation). Sodium thiosulfate can be formed by disproportionation of sulfur dissolving in sodium hydroxide (similar to phosphorus ).
Thiosulfate ions reacts with acids to give sulfur dioxide and various sulfur rings: [ 4 ]
This reaction may be used to generate sulfur colloids and demonstrate the Rayleigh scattering of light in physics . If white light is shone from below, blue light is seen from sideways and orange light from above, due to the same mechanisms that color the sky at midday and dusk . [ citation needed ]
Thiosulfate ions react with iodine to give tetrathionate ions:
This reaction is key for iodometry .
With bromine (X = Br) and chlorine (X = Cl), thiosulfate ions are oxidized to sulfate ions:
Thiosulfate ion extensively forms diverse complexes with transition metals . This reactivity is related to its role in of silver-based photography .
Also reflecting its affinity for metals , thiosulfate ion rapidly corrodes metals in acidic conditions. Steel and stainless steel are particularly sensitive to pitting corrosion induced by thiosulfate ions. Molybdenum improves the resistance of stainless steel toward pitting (AISI 316L hMo). In alkaline aqueous conditions and medium temperature (60 °C), carbon steel and stainless steel (AISI 304L, 316L) are not attacked, even at high concentration of base (30%w KOH ), thiosulfate ion (10%w) and in presence of fluoride ion (5%w KF ). [ citation needed ]
In the era of silver-based photography , thiosulfate salts were consumed on a large scale as a "fixer" reagent. This application exploits thiosulfate ion's ability to dissolve silver halides . Sodium thiosulfate , commonly called hypo (from "hyposulfite"), was widely used in photography to fix black and white negatives and prints after the developing stage; modern "rapid" fixers use ammonium thiosulfate as a fixing salt because it acts three to four times faster. [ 5 ]
Thiosulfate salts have been used to extract or leach gold and silver from their ores as a less toxic alternative to cyanide ion. [ 2 ]
The enzyme rhodanase (thiosulfate sulfurtransferase) catalyzes the detoxification of cyanide ion by thiosulfate ion by transforming them into thiocyanate ion and sulfite ion:
Sodium thiosulfate has been considered as an empirical treatment for cyanide poisoning, along with hydroxocobalamin . It is most effective in a pre-hospital setting, since immediate administration by emergency personnel is necessary to reverse rapid intracellular hypoxia caused by the inhibition of cellular respiration , at complex IV . [ 6 ] [ 7 ] [ 8 ] [ 9 ]
It activates thiosulfate sulfurtransferase ( TST ) in mitochondria. TST is associated with protection against obesity and type II (insulin resistant) diabetes . [ 10 ] [ 11 ]
Thiosulfate can also work as electron donor for growth of bacteria oxidizing sulfur , such as Chlorobium limicola forma thiosulfatophilum . These bacteria use electrons from thiosulfate (and other sources) and carbon from carbon dioxide to synthesize carbon compounds through reverse Krebs cycle . [ 12 ]
Some bacteria can metabolise thiosulfates. [ 13 ]
Thiosulfate ion is a component of the very rare mineral sidpietersite Pb 4 (S 2 O 3 )O 2 (OH) 2 . [ 14 ] The presence of this anion in the mineral bazhenovite was disputed. [ 15 ]
Thiosulfate is an acceptable common name and used almost always.
The functional replacement IUPAC name is sulfurothioate ; the systematic additive IUPAC name is trioxidosulfidosulfate(2−) or trioxido-1 κ 3 O -disulfate( S — S )(2−) . [ 1 ]
Thiosulfate also refers to the esters of thiosulfuric acid , e.g. O , S -dimethyl thiosulfate CH 3 −O−S(=O) 2 −S−CH 3 . Such species are rare. | https://en.wikipedia.org/wiki/S2O3 |
The dithionite is the oxyanion with the formula [S 2 O 4 ] 2− . [ 1 ] It is commonly encountered as the salt sodium dithionite . For historical reasons, it is sometimes called hydrosulfite , but it contains no hydrogen and is not a sulfite . [ 2 ] The dianion has a steric number of 4 and trigonal pyramidal geometry.
In its main applications, dithionite is generally prepared in situ by reduction of sulfur dioxide by sodium borohydride , described by the following idealized equation: [ 3 ]
Dithionite is a reducing agent . At pH 7, its reduction potential is −0.66 V vs SHE . Its oxidation occurs with formation of sulfite : [ 4 ]
Dithionite undergoes acid hydrolytic disproportionation to thiosulfate and bisulfite : [ 2 ]
It also undergoes alkaline hydrolytic disproportionation to sulfite and sulfide : [ 2 ]
It is formally derived from dithionous acid (H 2 S 2 O 4 ), but this acid does not exist in any practical sense.
Sodium dithionite finds widespread use in industry as a reducing agent . It is for example used in bleaching of wood pulp and some dyes . [ 3 ]
Dithionite is used in conjunction with complexing agents (for example, citric acid ) to reduce iron (III) oxy-hydroxide into soluble iron(II) compounds and to remove amorphous iron(III)-bearing mineral phases in soil analyses (selective extraction).
The decomposition of dithionite produces reduced species of sulfur that can be very aggressive for the corrosion of steel and stainless steel . Thiosulfate ( S 2 O 2− 3 ) is known to induce pitting corrosion , whereas sulfide (S 2− , HS − ) is responsible for stress corrosion cracking (SCC).
This corrosion -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/S2O4 |
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