id int64 580 79M | url stringlengths 31 175 | text stringlengths 9 245k | source stringlengths 1 109 | categories stringclasses 160
values | token_count int64 3 51.8k |
|---|---|---|---|---|---|
38,508,096 | https://en.wikipedia.org/wiki/EPI-001 | EPI-001 is the first inhibitor of the androgen receptor amino-terminal domain. The single stereoisomer of EPI-001, EPI-002, is a first-in-class drug that the USAN council assigned a new stem class "-aniten" and the generic name "ralaniten". This distinguishes the anitens novel molecular mechanism from anti androgens that bind the C-terminus ligand-binding domain and have the stem class "lutamide" (such as flutamide, nilutamide, bicalutamide, enzalutamide, etc.). EPI-001 and its stereoisomers and analogues were discovered by Marianne Sadar and Raymond Andersen, who co-founded the pharmaceutical company ESSA Pharma Inc (Vancouver, Canada) for the clinical development of anitens for the treatment of castration-resistant prostate cancer (CRPC).
EPI-001 is an antagonist of the androgen receptor (AR) that acts by binding covalently to the N-terminal domain (NTD) of the AR and blocking protein-protein interactions required for transcriptional activity of the AR and its splice variants (IC50 for inhibition of AR NTD transactivation ≈ 6 μM). This is different from all currently-used antiandrogens, which, conversely, bind to the C-terminal ligand-binding domain (LBD) of the AR and competitively block binding and activation of the receptor by androgens. Due to its unique mechanism of action, EPI-001 type compounds may prove to be effective in the treatment of advanced prostate cancer resistant to conventional antiandrogens such as enzalutamide.
EPI-001's successor, ralaniten acetate (EPI-506), a prodrug of ralaniten (EPI-002), one of the four stereoisomers of EPI-001, was under clinical investigation in a phase I study. EPI-506 was the first drug that directly binds to an intrinsically disordered region to be tested in humans and marks a leap in drug development from folded drug targets.
Pharmacology
Pharmacodynamics
EPI-001 is a mixture of four stereoisomers. EPI-001 binds to the activation function-1 (AF-1) region in the NTD of the AR, as opposed to other AR antagonists, which bind to the C-terminal LBD. A functional AF-1 is essential for the AR to have transcriptional activity. If AF-1 is deleted or mutated, the AR will still bind androgens, but will have no transcriptional activity. Importantly, if the AR lacks an LBD, the receptor will be nuclear and constitutively-active. Constitutively active splice variants of the AR that lack the C-terminal LBD are correlated to CRPC and poor survival. EPI-001 is an inhibitor of constitutively active splice variant of ARs that lack the C-terminal LBD. Conventional antiandrogens do not inhibit constitutively-active variants of AR that have a truncated or deleted C-terminal LBD.
In the absence of androgen, all known antiandrogens cause translocation of AR from the cytoplasm to the nucleus, whereas EPI-001 does not cause the AR to become nuclear. Binding of EPI-001 to the NTD of the AR blocks protein-protein interactions that are essential for its transcriptional activity. Specifically, EPI-001 blocks AR interactions with CREB-binding protein, RAP74, and between the NTD and C-terminal domain (termed N/C interaction) required for antiparallel dimer formation of AR. Unlike antiandrogens such as bicalutamide, EPI-001 does not cause the AR to bind to androgen response elements on the DNA of target genes.
EPI-001 at extremely high concentrations of 50 to 200 uM has also been found to act as a selective PPARγ modulator (SPPARM), with both agonistic and antagonistic actions on the PPARγ. Via PPARγ activation, EPI-001 has been found to inhibit AR expression and activity in prostate cancer cells, indicating at least one AR-independent action by which EPI-001 exhibits antiandrogen properties in the prostate.
EPI-001 inhibits AR-dependent proliferation of human prostate cancer cells while having no significant effects on cells that do not require the AR for growth and survival. EPI-001 has specificity to the AR (aside from the PPARγ) and has excellent anti-tumor activity in vivo with xenografts of CRPC.
See also
EPI-002
EPI-7386
References
Abandoned drugs
Alkylating agents
2,2-Bis(4-hydroxyphenyl)propanes
Halohydrins
Nonsteroidal antiandrogens
Organochlorides
PPAR agonists
Triols
Glycerols | EPI-001 | Chemistry | 1,048 |
78,607,422 | https://en.wikipedia.org/wiki/Potassium%20asparaginate | Potassium asparaginate is a potassium salt of L-asparagine amino acid.
Potassium asparaginate can be considered both a salt and a coordination complex. As a salt, potassium asparaginate is formed when the potassium ion () replaces the hydrogen ion () in the carboxyl group of L-asparagine, an amino acid; in this process, the carboxyl group (COOH) in L-asparagine loses hydrogen which is replaced by potassium. As a coordination complex, in the context of coordination chemistry, the potassium ion coordinates with the L-asparagine, forming a stable structure where the central (metal) ion is surrounded by and associated with the L-asparagine, a ligand (complexing molecule), through coordinate covalent bonds.
Chemical properties
The composition by mass of elemental potassium () in potassium asparaginate () is approximately 23%, given that the molar mass of a potassium atom (K) is 39.1 grams per mole (g/mol), and the molar mass of a potassium asparaginate is 170.21 g/mol (39.1/170.21≈23%).
The solubility of potassium asparaginate, in g/100ml of various solvents (water, ethanol, methanol), at temperatures of 30, 35 and 40 degree Celsius, is the following:
Synthesis
Potassium asparaginate can be obtained from L-asparagine and potassium fluoride (KF) in a chemical reaction which yields potassium asparaginate and hydrofluoric acid (HF).
Applications
Medicine
Potassium asparaginate, along with magnesium asparaginate, is marketed in Russia and Eastern European countries to treat or prevent potassium deficiency (hypokalemia) and magnesium deficiency (hyponatremia). Potassium asparaginate and magnesium asparaginate purportedly improve metabolism in the myocardium (heart muscle), enhance the tolerance of cardiac glycosides (heart medications) and exhibit antiarrhythmic activity (help regulate heart rhythm). Still, these health claims are not backed up by reliable studies. In the United States, potassium asparaginate is not specifically approved by the Food and Drug Administration (FDA) for treating any medical condition; to treat hypokalemia, potassium is instead administered as other salts, namely, gluconate, citrate, chloride or bicarbonate.
Nonlinear optics
In nonlinear optics, crystals of potassium asparaginate are investigated as a potential nonlinear optical material, as salts of some amino acids possess strong nonlinear optical properties. A nonlinear optics material is a substance with high optical nonlinearity. Such substances are useful in applications such as signal transmission, data storage, or optical switching. High optical nonlinearity refers to the property of materials to respond to light (e.g., a laser) in a nonlinear manner, meaning that the property doesn't scale linearly with the intensity of the light applied.
References
Potassium compounds
Optical materials
Metal-amino acid complexes | Potassium asparaginate | Physics,Chemistry | 647 |
48,618,702 | https://en.wikipedia.org/wiki/NGC%204041 | NGC 4041 is the New General Catalogue identifier for a spiral galaxy in the northern circumpolar constellation of Ursa Major. It is located an estimated 70 million light years from the Sun. The morphological classification of SA(rs)bc indicates this is a spiral galaxy the lacks a bar; the 'rs' means it has a weakly-formed ring structure, and the 'bc' indicates the spiral arms are moderately to loosely wound.
The galaxy is inclined by around 20° to the line of sight from the Earth. It is forming new stars at the estimated rate of , which is fairly typical for a galaxy of this morphology. The star formation rate is much higher in the central region, which may be the result of recent merger with a dwarf galaxy within the last 100 million years.
This galaxy has no detected activity in the nuclear region. There is a rotating nuclear disk of high brightness at the core that is consistent with the presence of a compact mass of . Most likely this is a supermassive black hole (SMBH).
On July 29, 1994, the type IIp supernova designated SN 1994W was discovered in this galaxy by Giancarlo Cortini and Mirko Villi. The event reached peak visual magnitude on August 13, and declined thereafter. It was located about 19 arc seconds to the northwest of the nucleus. This supernova was unusual for the exceptionally low quantity of nickel-56 released—indeed, it was the lowest inferred amount measured for any type II supernova as of that date. Based upon a possible detection of X-ray emission from the remnant, this may be a high-luminosity type IIn supernova.
NGC 4041 is a member of the LGG 266 galaxy group, along with NGC 4036, IC 758, UGC 7009, and UGC 7019. It is located just 17 arc minutes from NGC 4036, and the two form a pair with a projected separation of around .
References
External links
Unbarred spiral galaxies
Ursa Major
4041
7014
037999 | NGC 4041 | Astronomy | 423 |
44,167,948 | https://en.wikipedia.org/wiki/Aristides%20Patrinos | Dr. Aristides Patrinos () is an expert in synthetic biology, and a former leader of the Human Genome Project.
Biography
Patrinos was born in 1947 to parents of Greek ancestry in Alexandria, Egypt. After attending and graduating Greek and British schools, in 1965 he left Cairo and moved to Athens, Greece. He studied engineering, both electrical and mechanical, at the National Technical University of Athens. Upon receiving his degree in 1970, he moved to the U.S. and studied in Chicago, Illinois at Northwestern University. In 1975, after receiving his Ph.D, he moved to New York State and taught at the University of Rochester. From there he worked with the Department of Energy and their national laboratories in New York state and Tennessee, eventually settling in Washington D.C., where he joined the U. S. Department of Energy full time. He is married to Kathryn Hoff and they have two daughters.
Career
In 1993, Patrinos succeeded David J. Galas as the Director of the Office of Biological and Environmental Research in the U.S. Department of Energy, where he worked on the Human Genome Project. He launched the Genomes to Life Program and created the DOE Joint Genome Institute. At DOE he was also involved in initiating the International Panel on Climate Change and the Global Change Research Program within the Department of Energy. His work and research has defined many of the policies the United States employs with regard to these fields.
He left the Department of Energy in 2006, and joined Synthetic Genomics Inc.
Patrinos is considered a leading authority on structural biology, genomics, global environmental change, and nuclear medicine. He currently directs research for Urban Sciences and Progress or the CUSP program, and is also a professor of biological, chemical, and mechanical engineering at New York University. He continues to be involved with Synthetic Genome and their project, and also serves on the Board of Directors of Tsakos Energy and Navigation (TNP). He also continues work in Washington D.C. advocating solutions for sustainable global energy and environmental change.
Awards
Patrinos has received two Secretary's Gold Honor awards from the Department of Energy, and three Presidential Rank Awards, and several honorary degrees.
References
External links
Aristides A. N. Patrinos Deputy Director for Research
Dr. Aristides Patrinos Named President of Synthetic Genomics, Inc.
The scientist behind the miracle of synthetic biology
1947 births
Greek academics
Greek scientists
New York University faculty
Northwestern University alumni
Living people
National Technical University of Athens alumni
People from Alexandria
Egyptian people of Greek descent
Synthetic biologists
20th-century Greek Americans
20th-century Greek scientists | Aristides Patrinos | Biology | 533 |
25,941,423 | https://en.wikipedia.org/wiki/Tin%20sources%20and%20trade%20during%20antiquity | Tin is an essential metal in the creation of tin-bronzes, and its acquisition was an important part of ancient cultures from the Bronze Age onward. Its use began in the Middle East and the Balkans around 3000 BC. Tin is a relatively rare element in the Earth's crust, with about two parts per million (ppm), compared to iron with 50,000 ppm, copper with 70 ppm, lead with 16 ppm, arsenic with 5 ppm, silver with 0.1 ppm, and gold with 0.005 ppm. Ancient sources of tin were therefore rare, and the metal usually had to be traded over very long distances to meet demand in areas which lacked tin deposits.
Known sources of tin in ancient times include the southeastern tin belt that runs from Yunnan in China to the Malay Peninsula; Cornwall and Devon in Britain; Brittany in France; the border between Germany and the Czech Republic; Spain; Portugal; Italy; and central and South Africa. Syria and Egypt have been suggested as minor sources of tin, but the archaeological evidence is inconclusive.
Early use
Tin extraction and use can be dated to the beginning of the Bronze Age around 3000 BC, during which copper objects formed from polymetallic ores had different physical properties. The earliest bronze objects had tin or arsenic content of less than 2% and are therefore believed to be the result of unintentional alloying due to trace metal content in copper ores such as tennantite, which contains arsenic. The addition of a second metal to copper increases its hardness, lowers the melting temperature, and improves the casting process by producing a more fluid melt that cools to a denser, less spongy metal. This was an important innovation that allowed for the much more complex shapes cast in closed molds of the Bronze Age. Arsenical bronze objects appear first in the Middle East where arsenic is commonly found in association with copper ore, but the health risks were quickly realized and the quest for sources of the much less hazardous tin ores began early in the Bronze Age. This created the demand for rare tin metal and formed a trade network that linked the distant sources of tin to the markets of Bronze Age cultures.
Cassiterite (SnO2), oxidized tin, most likely was the original source of tin in ancient times. Other forms of tin ores are less abundant sulfides such as stannite that require a more involved smelting process. Cassiterite often accumulates in alluvial channels as placer deposits due to the fact that it is harder, heavier, and more chemically resistant than the granite in which it typically forms. These deposits can be easily seen in river banks, because cassiterite is usually black or purple or otherwise dark, a feature exploited by early Bronze Age prospectors. It is likely that the earliest deposits were alluvial and perhaps exploited by the same methods used for panning gold in placer deposits.
Archaeological importance
The importance of tin to the success of Bronze Age cultures and the scarcity of the resource offers a glimpse into that time period's trade and cultural interactions, and has therefore been the focus of intense archaeological studies. However, a number of problems have plagued the study of ancient tin such as the limited archaeological remains of placer mining, the destruction of ancient mines by modern mining operations, and the poor preservation of pure tin objects due to tin disease or tin pest. These problems are compounded by the difficulty in provenancing tin objects and ores to their geological deposits using isotopic or trace element analyses. Current archaeological debate is concerned with the origins of tin in the earliest Bronze Age cultures of the Near East.
Ancient sources
Europe
Europe has very few sources of tin. Therefore, throughout ancient times it was imported long distances from the known tin mining districts of antiquity. These were the Ore Mountains (Erzgebirge) along the modern border between Germany and the Czech Republic, the Iberian Peninsula, Brittany in modern France, and Cornwall and Devon in southwestern Britain.
There are several smaller sources of tin in the Balkans and another minor source of tin is known to exist at Monte Valerio in Tuscany, Italy. The Tuscan source was exploited by Etruscan miners around 800 BC, but it was not a significant source of tin for the rest of the Mediterranean. Even at that time, the Etruscans themselves had to import additional tin from the northwest of the Iberian Peninsula, and later from Cornwall.
It has been claimed that tin was first mined in Europe around 2500 BC in the Erzgebirge, and knowledge of tin bronze and tin extraction techniques spread from there to Brittany and Cornwall around 2000 BC and from northwestern Europe to northwestern Spain and Portugal around the same time. However, the only Bronze Age object from Central Europe whose tin has been scientifically provenanced is the Nebra sky disk, and its tin (and gold, though not its copper), is shown by tin isotopes to have come from Cornwall. In addition, a rare find of a pure tin ingot in Scandinavia was provenanced to Cornwall. Available evidence, though very limited, thus points to Cornwall as the sole early source of tin in Central and Northern Europe.
Cornwall and Devon were important sources of tin for Europe and the Mediterranean throughout ancient times and may have been the earliest sources of tin in Western Europe, with evidence for trade to the Eastern Mediterranean by the Late Bronze Age. Within recorded history, Cornwall and Devon only dominated the European market for tin from late Roman times, starting around the 3rd century AD, as many Spanish tin mines were exhausted. Cornwall maintained its importance as a source of tin throughout medieval times and into the modern period.
Brittany – opposite Cornwall on the Celtic Sea – has significant sources of tin which show evidence of being extensively exploited after the Roman conquest of Gaul during the 50s BC and onwards. Brittany remained a significant source of tin throughout the medieval period.
A group of 52 bronze artifacts from the late Bronze Age Balkans has been shown to have tin of multiple origins, based on the correlation of tin isotope differences with the different find locations of the artifacts. While the locations of these separate tin sources are uncertain, the larger Serbian group of artifacts is inferred to be derived from tin sources in western Serbia (e.g. Mount Cer), while the smaller group, largely from western Romania, is inferred to have western Romanian origins.
Iberian tin was widely traded across the Mediterranean during the Bronze Age, and extensively exploited during Roman times. But Iberian tin deposits were largely forgotten throughout the medieval period, were not rediscovered until the 18th century, and only re-gained importance during the mid-19th century.
Asia
Western Asia has very little tin ore; the few sources that have recently been found are too insignificant to have played a major role during most of ancient history. However, it is possible that they were exploited at the start of the Bronze Age and are responsible for the development of early bronze manufacturing technology. Kestel, in Southern Turkey, is the site of an ancient cassiterite mine that was used from 3250 to 1800 BC. It contains miles of tunnels, some only large enough for a child. A grave with children who were probably workers has been found. It was abandoned, with crucibles and other tools left at the site.
While there are a few sources of cassiterite in Central Asia, namely in Uzbekistan, Tajikistan, and Afghanistan, that show signs of having been exploited starting around 2000 BC, archaeologists disagree about whether they were significant sources of tin for the earliest Bronze Age cultures of the Middle East.
In Northern Asia the only tin deposits considered exploitable by ancient peoples occur in the far eastern region of Siberia. This source of tin appears to have been exploited by the Eurasian Steppe people known as the Seima-Turbino culture around 2000 BC as well as by northern Chinese cultures around the same time.
Eastern Asia has a number of small cassiterite deposits along the Yellow River which were exploited by the earliest Chinese Bronze Age culture of Erlitou and the Shang dynasty (2500 to 1800 BC). However, the richest deposits for the region, and indeed the world, lie in Southeastern Asia, stretching from Yunnan in China to the Malay Peninsula. The deposits in Yunnan were not mined until around 700 BC, but by the Han dynasty had become the main source of tin in China according to historical texts of the Han, Jin, Tang, and Song dynasties. Other cultures of Southeast Asia exploited the abundant cassiterite resources sometime between the third and second millennia BC, but due to the lack of archaeological work in the region little else is known about tin exploitation during ancient times in that part of the world.
Tin was used in the Indian subcontinent starting between 1500 and 1000 BC. While India does have some small scattered deposits of tin, they were not a major source of tin for Indian Bronze Age cultures as shown by their dependence on imported tin.
Africa
While rich veins of tin are known to exist in Central and South Africa, whether these were exploited during ancient times is still debated . However, the Bantu culture of Zimbabwe are known to have actively mined, smelted and traded tin between the 11th and 15th centuries AD.
Americas
Tin deposits exist in many parts of South America, with minor deposits in southern Peru, Colombia, Brazil, and northwestern Argentina, and major deposits of exploitable cassiterite in northern Bolivia. These deposits were exploited as early as 1000 AD in the manufacture of tin bronze by Andean cultures, including the later Inca Empire, which considered tin bronze the "imperial alloy". In North America, the only known exploitable source of tin during ancient times is located in the Zacatecas tin province of north central Mexico which supplied west Mexican cultures with enough tin for bronze production.
Australia
The tin belt of Southeast Asia extends all the way down to Tasmania, but metals were not exploited in Australia until the arrival of Europeans in the 1780s.
Trade
Due to the scattered nature of tin deposits around the world and its essential nature for the creation of tin bronze, tin trade played an important role in the development of cultures throughout ancient times. Archaeologists have reconstructed parts of the extensive trade networks of ancient cultures from the Bronze Age to modern times using historical texts, archaeological excavations, and trace element and lead isotope analysis to determine the origins of tin objects around the world.
Mediterranean
The earliest sources of tin in the Early Bronze Age in the Near East are still unknown and the subject of much debate in archaeology. Possibilities include minor now-depleted sources in the Near East, trade from Central Asia, Sub-Saharan Africa, Europe, or elsewhere.
It is possible that as early as 2500 BC, the Ore Mountains had begun exporting tin, using the well established Baltic amber trade route to supply Scandinavia as well as the Mediterranean with tin. By 2000 BC, the extraction of tin in Britain, France, Spain, and Portugal had begun and tin was traded to the Mediterranean sporadically from all these sources. Evidence of tin trade in the Mediterranean can be seen in a number of Bronze Age shipwrecks containing tin ingots such as the Uluburun off the coast of Turkey dated 1300 BC which carried over 300 copper bars weighing 10 tons, and approximately 40 tin bars weighing 1 ton. Evidence of direct tin trade between Europe and the Eastern Mediterranean has been demonstrated through the analysis of tin ingots dated to the 13th-12th centuries BC from sites in Israel, Turkey and modern-day Greece; tin ingots from Israel, for example, have been found to share chemical composition with tin from Cornwall and Devon (Great Britain).
While Sardinia does not appear to have much in terms of significant sources of tin, it does have rich copper and other mineral wealth and served as a centre for metals trade during the Bronze Age and likely actively imported tin from the Iberian Peninsula for export to the rest of the Mediterranean.
By classical Greek times, the tin sources were well established. Greece and the Western Mediterranean appear to have traded their tin from European sources, while the Middle East acquired their tin from Central Asian sources through the Silk Road. For example, Iron Age Greece had access to tin from Iberia by way of the Phoenicians who traded extensively there, from the Erzgebirge by way of the Baltic Amber Road overland route, or from Brittany and Cornwall through overland routes from their colony at Massalia (modern day Marseilles) established in the 6th century BC. In 450 BC, Herodotus described tin as coming from Northern European islands named the Cassiterides along the extreme borders of the world, suggesting very long-distance trade, likely from Britain, northwestern Iberia, or Brittany, supplying tin to Greece and other Mediterranean cultures. The idea that the Phoenicians went to Cornwall for its tin and supplied it to the whole of the Mediterranean has no archaeological basis and is largely considered a myth.
The early Roman world was mainly supplied with tin from its Iberian provinces of Gallaecia and Lusitania and to a lesser extent Tuscany. Pliny mentions that in 80 BC, a senatorial decree halted all mining on the Italian Peninsula, stopping any tin mining activity in Tuscany and increasing Roman dependence on tin from Brittany, Iberia, and Cornwall. After the Roman conquest of Gaul, Brittany's tin deposits saw intensified exploitation after the first century BC. With the exhaustion of the Iberian tin mines, Cornwall became a major supplier of tin for the Romans after the 3rd century AD.
Throughout the medieval period, demand for tin increased as pewter gained popularity. Brittany and Cornwall remained the major producers and exporters of tin throughout the Mediterranean through to modern times.
Asia
Near Eastern development of bronze technology spread across Central Asia by way of the Eurasian Steppes, and with it came the knowledge and technology for tin prospection and extraction. By 2000 to 1500 BC Uzbekistan, Afghanistan, and Tajikistan appear to have exploited their sources of tin, carrying the resources east and west along the Silk Road crossing Central Asia. This trade link likely followed an existing trade route of lapis lazuli, a highly prized semi-precious blue gemstone, and chlorite vessels decorated with turquoise from Central Asia that have been found as far west as Egypt and that date to the same period.
In China, early tin was extracted along the Yellow River in Erlitou and Shang times between 2500 and 1800 BC. By Han and later times, China imported its tin from what is today Yunnan province. This has remained China's main source of tin throughout history and into modern times.
It is unlikely that Southeast Asian tin from Indochina was widely traded around the world in ancient times as the area was only opened up to Indian, Muslim, and European traders around 800 AD.
Indo–Roman trade relations are well known from historical texts such as Pliny's Natural History (book VI, 26), and tin is mentioned as one of the resources being exported from Rome to South Arabia, Somaliland, and India.
See also
Cassiterides
Stannary
Tin pest
Tin mining in Britain
Mining in Cornwall and Devon
Dartmoor tin mining
References
Cited works
History of mining
History of metallurgy
Tin mining
Bronze Age
Ancient international relations
Trade | Tin sources and trade during antiquity | Chemistry,Materials_science | 3,055 |
4,902,017 | https://en.wikipedia.org/wiki/Parametric%20oscillator | A parametric oscillator is a driven harmonic oscillator in which the oscillations are driven by varying some parameters of the system at some frequencies, typically different from the natural frequency of the oscillator. A simple example of a parametric oscillator is a child pumping a playground swing by periodically standing and squatting to increase the size of the swing's oscillations. The child's motions vary the moment of inertia of the swing as a pendulum. The "pump" motions of the child must be at twice the frequency of the swing's oscillations. Examples of parameters that may be varied are the oscillator's resonance frequency and damping .
Parametric oscillators are used in several areas of physics. The classical varactor parametric oscillator consists of a semiconductor varactor diode connected to a resonant circuit or cavity resonator. It is driven by varying the diode's capacitance by applying a varying bias voltage. The circuit that varies the diode's capacitance is called the "pump" or "driver". In microwave electronics, waveguide/YAG-based parametric oscillators operate in the same fashion. Another important example is the optical parametric oscillator, which converts an input laser light wave into two output waves of lower frequency ().
When operated at pump levels below oscillation, the parametric oscillator can amplify a signal, forming a parametric amplifier (paramp). Varactor parametric amplifiers were developed as low-noise amplifiers in the radio and microwave frequency range. The advantage of a parametric amplifier is that it has much lower noise than an amplifier based on a gain device like a transistor or vacuum tube. This is because in the parametric amplifier a reactance is varied instead of a (noise-producing) resistance. They are used in very low noise radio receivers in radio telescopes and spacecraft communication antennas.
Parametric resonance occurs in a mechanical system when a system is parametrically excited and oscillates at one of its resonant frequencies. Parametric excitation differs from forcing since the action appears as a time varying modification on a system parameter.
History
Parametric oscillations were first noticed in mechanics. Michael Faraday (1831) was the first to notice oscillations of one frequency being excited by forces of double the frequency, in the crispations (ruffled surface waves) observed in a wine glass excited to "sing". Franz Melde (1860) generated parametric oscillations in a string by employing a tuning fork to periodically vary the tension at twice the resonance frequency of the string. Parametric oscillation was first treated as a general phenomenon by Rayleigh (1883,1887).
One of the first to apply the concept to electric circuits was George Francis FitzGerald, who in 1892 tried to excite oscillations in an LC circuit by pumping it with a varying inductance provided by a dynamo.
Parametric amplifiers (paramps) were first used in 1913-1915 for radio telephony from Berlin to Vienna and Moscow, and were predicted to have a useful future (Ernst Alexanderson, 1916). These early parametric amplifiers used the nonlinearity of an iron-core inductor, so they could only function at low frequencies.
In 1948 Aldert van der Ziel pointed out a major advantage of the parametric amplifier: because it used a variable reactance instead of a resistance for amplification it had inherently low noise. A parametric amplifier used as the front end of a radio receiver could amplify a weak signal while introducing very little noise. In 1952 Harrison Rowe at Bell Labs extended some 1934 mathematical work on pumped oscillations by Jack Manley and published the modern mathematical theory of parametric oscillations, the Manley-Rowe relations.
The varactor diode invented in 1956 had a nonlinear capacitance that was usable into microwave frequencies. The varactor parametric amplifier was developed by Marion Hines in 1956 at Western Electric. At the time it was invented microwaves were just being exploited, and the varactor amplifier was the first semiconductor amplifier at microwave frequencies. It was applied to low noise radio receivers in many areas, and has been widely used in radio telescopes, satellite ground stations, and long-range radar. It is the main type of parametric amplifier used today. Since that time parametric amplifiers have been built with other nonlinear active devices such as Josephson junctions.
The technique has been extended to optical frequencies in optical parametric oscillators and amplifiers which use nonlinear crystals as the active element.
Mathematical analysis
A parametric oscillator is a harmonic oscillator whose physical properties vary with time. The equation of such an oscillator is
This equation is linear in . By assumption, the parameters and depend only on time and do not depend on the state of the oscillator. In general, and/or are assumed to vary periodically, with the same period .
If the parameters vary at roughly twice the natural frequency of the oscillator (defined below), the oscillator phase-locks to the parametric variation and absorbs energy at a rate proportional to the energy it already has. Without a compensating energy-loss mechanism provided by , the oscillation amplitude grows exponentially. (This phenomenon is called parametric excitation, parametric resonance or parametric pumping.) However, if the initial amplitude is zero, it will remain so; this distinguishes it from the non-parametric resonance of driven simple harmonic oscillators, in which the amplitude grows linearly in time regardless of the initial state.
A familiar experience of both parametric and driven oscillation is playing on a swing. Rocking back and forth pumps the swing as a driven harmonic oscillator, but once moving, the swing can also be parametrically driven by alternately standing and squatting at key points in the swing arc. This changes moment of inertia of the swing and hence the resonance frequency, and children can quickly reach large amplitudes provided that they have some amplitude to start with (e.g., get a push). Standing and squatting at rest, however, leads nowhere.
Transformation of the equation
We begin by making a change of variable
where is the time integral of the damping coefficient
.
This change of variable eliminates the damping term in the differential equation, reducing it to
where the transformed frequency is defined as
.
In general, the variations in damping and frequency are relatively small perturbations
where and are constants, namely, the time-averaged oscillator frequency and damping, respectively. The transformed frequency can then be written in a similar way as
,
where is the natural frequency of the damped harmonic oscillator
and
.
Thus, our transformed equation can be written as
.
The independent variations and in the oscillator damping and resonance frequency, respectively, can be combined into a single pumping function . The converse conclusion is that any form of parametric excitation can be accomplished by varying either the resonance frequency or the damping, or both.
Solution of the transformed equation
Let us assume that is sinusoidal with a frequency approximately twice the natural frequency of the oscillator:
where the pumping frequency but need not equal exactly. Using the method of variation of parameters, the solution to our transformed equation may be written as
where the rapidly varying components, and have been factored out to isolate the slowly varying amplitudes and
We proceed by substituting this solution into the differential equation and considering that both the coefficients in front of and must be zero to satisfy the differential equation identically. We also omit the second derivatives of and on the grounds that and are slowly varying, as well as omit sinusoidal terms not near the natural frequency, as they do not contribute significantly to resonance. The result is the following pair of coupled differential equations:
This system of linear differential equations with constant coefficients can be decoupled and solved by eigenvalue/eigenvector methods. This yields the solution
where and are the eigenvalues of the matrix
and are corresponding eigenvectors, and and are arbitrary constants.
The eigenvalues are given by
If we write the difference between and as and replace with everywhere where the difference is not important, we get
.
If then the eigenvalues are real and exactly one is positive, which leads to exponential growth for and This is the condition for parametric resonance, with the growth rate for given by the positive eigenvalue
Note, however, that this growth rate corresponds to the amplitude of the transformed variable whereas the amplitude of the original, untransformed variable can either grow or decay depending on whether is an increasing or decreasing function of time,
Intuitive derivation of parametric excitation
The above derivation may seem like a mathematical sleight-of-hand, so it may be helpful to give an intuitive derivation. The equation may be written in the form
which represents a simple harmonic oscillator (or, alternatively, a bandpass filter) being driven by a signal that is proportional to its response .
Assume that already has an oscillation at frequency and that the pumping has double the frequency and a small amplitude . Applying a trigonometric identity for products of sinusoids, their product produces two driving signals, one at frequency and the other at frequency .
Being off-resonance, the signal is attenuated and can be neglected initially. By contrast, the signal is on resonance, serves to amplify , and is proportional to the amplitude . Hence, the amplitude of grows exponentially unless it is initially zero.
Expressed in Fourier space, the multiplication is a convolution of their Fourier transforms and . The positive feedback arises because the component of converts the component of into a driving signal at , and vice versa (reverse the signs). This explains why the pumping frequency must be near , twice the natural frequency of the oscillator. Pumping at a grossly different frequency would not couple (i.e., provide mutual positive feedback) between the and components of .
Parametric resonance
Parametric resonance is the parametrical resonance phenomenon of mechanical perturbation and oscillation at certain frequencies (and the associated harmonics). This effect is different from regular resonance because it exhibits the instability phenomenon.
Parametric resonance occurs in a mechanical system when a system is parametrically excited and oscillates at one of its resonant frequencies. Parametric excitation differs from forcing since the action appears as a time varying modification on a system parameter. The classical example of parametric resonance is that of the vertically forced pendulum. Parametric resonance takes place when the external excitation frequency equals twice the natural frequency of the system divided by a positive integer . For a parametric excitation with small amplitude in the absence of friction, the bandwidth of the resonance is to leading order . The effect of friction is to introduce a finite threshold for the amplitude of parametric excitation to result in an instability.
For small amplitudes and by linearising, the stability of the periodic solution is given by Mathieu's equation:
where is some perturbation from the periodic solution. Here the term acts as an ‘energy’ source and is said to parametrically excite the system. The Mathieu equation describes many other physical systems to a sinusoidal parametric excitation such as an LC Circuit where the capacitor plates move sinusoidally.
Autoparametric resonance happens in a system with two coupled oscillators, such that the vibrations of one act as parametric resonance on the second. The zero point of the second oscillator becomes unstable, and thus it starts oscillating.
Parametric amplifiers
Introduction
A parametric amplifier is implemented as a mixer. The mixer's gain shows up in the output as amplifier gain. The input weak signal is mixed with a strong local oscillator signal, and the resultant strong output is used in the ensuing receiver stages.
Parametric amplifiers also operate by changing a parameter of the amplifier. Intuitively, this can be understood as follows, for a variable capacitor-based amplifier.
Charge in a capacitor obeys: ,
therefore the voltage across is .
Knowing the above, if a capacitor is charged until its voltage equals the sampled voltage of an incoming weak signal, and if the capacitor's capacitance is then reduced (say, by manually moving the plates further apart), then the voltage across the capacitor will increase. In this way, the voltage of the weak signal is amplified.
If the capacitor is a varicap diode, then "moving the plates" can be done simply by applying time-varying DC voltage to the varicap diode. This driving voltage usually comes from another oscillator—sometimes called a "pump".
The resulting output signal contains frequencies that are the sum and difference of the input signal (f1) and the pump signal (f2): (f1 + f2) and (f1 − f2).
A practical parametric oscillator needs the following connections: one for the "common" or "ground", one to feed the pump, one to retrieve the output, and maybe a fourth one for biasing. A parametric amplifier needs a fifth port to input the signal being amplified. Since a varactor diode has only two connections, it can only be a part of an LC network with four eigenvectors with nodes at the connections. This can be implemented as a transimpedance amplifier, a traveling-wave amplifier or by means of a circulator.
Mathematical equation
The parametric oscillator equation can be extended by adding an external driving force :
.
We assume that the damping is sufficiently strong that, in the absence of the driving force , the amplitude of the parametric oscillations does not diverge, i.e., that . In this situation, the parametric pumping acts to lower the effective damping in the system. For illustration, let the damping be constant and assume that the external driving force is at the mean resonance frequency , i.e., . The equation becomes
whose solution is approximately
.
As approaches the threshold , the amplitude diverges. When , the system enters parametric resonance and the amplitude begins to grow exponentially, even in the absence of a driving force .
Advantages
It is highly sensitive
low noise level amplifier for ultra high frequency and microwave radio signal
Other relevant mathematical results
If the parameters of any second-order linear differential equation are varied periodically, Floquet analysis shows that the solutions must vary either sinusoidally or exponentially.
The equation above with periodically varying is an example of a Hill equation. If is a simple sinusoid, the equation is called a Mathieu equation.
See also
Harmonic oscillator
Mathieu equation
Optical parametric amplifier
Optical parametric oscillator
References
Further reading
Kühn L. (1914) Elektrotech. Z., 35, 816-819.
Pungs L. DRGM Nr. 588 822 (24 October 1913); DRP Nr. 281440 (1913); Elektrotech. Z., 44, 78-81 (1923?); Proc. IRE, 49, 378 (1961).
Elmer, Franz-Josef, "Parametric Resonance Pendulum Lab University of Basel". unibas.ch, July 20, 1998.
Cooper, Jeffery, "Parametric Resonance in Wave Equations with a Time-Periodic Potential". SIAM Journal on Mathematical Analysis, Volume 31, Number 4, pp. 821–835. Society for Industrial and Applied Mathematics, 2000.
"Driven Pendulum: Parametric Resonance". phys.cmu.edu (Demonstration of physical mechanics or classical mechanics. Resonance oscillations set up in a simple pendulum via periodically varying pendulum length.)
Mumford, W. W., "Some notes on the history of parametric transducers". Proceedings of the IRE, Volume 98, Number 5, pp. 848–853. Institute of Electrical and Electronics Engineers, May 1960.
2009, Ferdinand Verhulst, Perturbation analysis of parametric resonance, Encyclopedia of Complexity and Systems Science, Springer.
External links
Tim's Autoparametric Resonance — a video by Tim Rowett showing how autoparametric resonance appears in a pendulum made with a spring.
Electronic amplifiers
Dynamical systems
Electronic oscillators
Ordinary differential equations | Parametric oscillator | Physics,Mathematics,Technology | 3,436 |
18,309 | https://en.wikipedia.org/wiki/Lucifer | The most common meaning for Lucifer in English is as a name for the Devil in Christian theology. He appeared in the King James Version of the Bible in Isaiah and before that in the Vulgate (the late-4th-century Latin translation of the Bible), not as the name of a devil but as the Latin word (uncapitalized), meaning "the morning star", "the planet Venus", or, as an adjective, "light-bringing". It is a translation of the Hebrew word , meaning "Shining One".
As the Latin name for the morning appearances of the planet Venus, it corresponds to the Greek names Phosphorus , "light-bringer", and Eosphorus , "dawn-bringer". The entity's Latin name was subsequently absorbed into Christianity as a name for the Devil. Modern scholarship generally translates the term in the relevant Bible passage (Isaiah 14:12), where the Greek Septuagint reads ὁ ἑωσφόρος ὁ πρωὶ ἀνατέλλων, as "morning star" or "shining one" rather than as a proper noun, Lucifer, as found in the Latin Vulgate.
As a name for the planet in its morning aspect, "Lucifer" (Light-Bringer) is a proper noun and is capitalized in English. In Greco-Roman civilization, he was often personified and considered a god and in some versions considered a son of Aurora (the Dawn). A similar name used by the Roman poet Catullus for the planet in its evening aspect is "Noctifer" (Night-Bringer).
Roman folklore and etymology
In Roman folklore, Lucifer ("light-bringer" in Latin) was the name of the planet Venus, though he was often personified as a male figure bearing a torch. The Greek name for this planet was variously Phosphoros (also meaning "light-bringer") or Heosphoros (meaning "dawn-bringer"). Lucifer was said to be "the fabled son of Aurora and Cephalus, and father of Ceyx". He was often presented in poetry as heralding the dawn.The Latin word corresponding to Greek is . It is used in its astronomical sense both in prose and poetry. Poets sometimes personify the star, placing it in a mythological context.
Lucifer's mother Aurora corresponds to goddesses in other cultures. The name "Aurora" is cognate to the name of the Vedic goddess Denu is the daughter of king 'Daksha'. That of the Lithuanian goddess Aušrinė, and that of the Greek goddess Eos, all three of whom are also goddesses of the dawn. All four are considered derivatives of the Proto-Indo-European stem (later ), "dawn", a stem that also gave rise to Proto-Germanic , Old Germanic and Old English (whence also Modern German "" meaning "Eastern Empire", as well as Modern English "east".) This agreement has led scholars to reconstruct a Proto-Indo-European dawn goddess.
The 2nd-century Roman mythographer Pseudo-Hyginus said of the planet:
The Latin poet Ovid, in his 1st-century epic , describes Lucifer as ordering the heavens:
Ovid, speaking of Phosphorus and Hesperus (the Evening Star, the evening appearance of the planet Venus) as identical, makes him the father of Daedalion. Ovid also makes him the father of Ceyx, while the Latin grammarian Servius makes him the father of the Hesperides or of Hesperis.
In the classical Roman period, Lucifer was not typically regarded as a deity and had few, if any, myths, though the planet was associated with various deities and often poetically personified. Cicero stated that "You say that Sol and Luna are deities, and the Greeks identify the former with Apollo and the latter with Diana. But if Luna is a goddess, then Lucifer (the Morning-Star) also and the rest of the Wandering Stars () will have to be counted gods; and if so, then the Fixed Stars () as well."
Planet Venus, Sumerian folklore, and fall from heaven motif
The motif of a heavenly being striving for the highest seat of heaven only to be cast down to the underworld has its origins in the motions of the planet Venus, known as the morning star.
A similar theme is present in the Babylonian myth of Etana. The Jewish Encyclopedia comments:
The fall from heaven motif also has a parallel in Canaanite mythology. In ancient Canaanite religion, the morning star is personified as the god Attar, who attempted to occupy the throne of Ba'al and, finding he was unable to do so, descended and ruled the underworld. The original myth may have been about the lesser god Helel trying to dethrone the Canaanite high god El, who lived on a mountain to the north. Hermann Gunkel's reconstruction of the myth told of a mighty warrior called Hêlal, whose ambition was to ascend higher than all the other stellar divinities, but who had to descend to the depths; it thus portrayed as a battle the process by which the bright morning star fails to reach the highest point in the sky before being faded out by the rising sun.
This Jewish tradition has echoes also in Jewish pseudepigrapha such as 2 Enoch and the Life of Adam and Eve. The Life of Adam and Eve, in turn, shaped the idea of Iblis in the Quran.
Christianity
In the Bible
In the Book of Isaiah, chapter 14, the king of Babylon is condemned in a prophetic vision by the prophet Isaiah and is called (, Hebrew for "shining one, son of the morning"), who is addressed as (). The title refers to the planet Venus as the morning star, and that is how the Hebrew word is usually interpreted. The Hebrew word transliterated as or , occurs only once in the Hebrew Bible. The Septuagint renders in Greek as (), "bringer of dawn", the Ancient Greek name for the morning star. Similarly the Vulgate renders in Latin as , the name in that language for the morning star. According to the King James Bible-based Strong's Concordance, the original Hebrew word means "shining one, light-bearer", and the English translation given in the King James text is the Latin name for the planet Venus, "Lucifer", as it was already in the Wycliffe Bible.
However, the translation of as "Lucifer" has been abandoned in modern English translations of Isaiah 14:12. Present-day translations render as "morning star" (New International Version, New Century Version, New American Standard Bible, Good News Translation, Holman Christian Standard Bible, Contemporary English Version, Common English Bible, Complete Jewish Bible), "daystar" (New Jerusalem Bible, The Message), "Day Star" (New Revised Standard Version, English Standard Version), "shining one" (New Life Version, New World Translation, JPS Tanakh), or "shining star" (New Living Translation).
In a modern translation from the original Hebrew, the passage in which the phrase "Lucifer" or "morning star" occurs begins with the statement: "On the day the Lord gives you relief from your suffering and turmoil and from the harsh labour forced on you, you will take up this taunt against the king of Babylon: How the oppressor has come to an end! How his fury has ended!" After describing the death of the king, the taunt continues:
For the unnamed "king of Babylon", a wide range of identifications have been proposed. They include a Babylonian ruler of the prophet Isaiah's own time, the later Nebuchadnezzar II, under whom the Babylonian captivity of the Jews began, or Nabonidus, and the Assyrian kings Tiglath-Pileser, Sargon II and Sennacherib. Verse 20 says that this king of Babylon will not be "joined with them [all the kings of the nations] in burial, because thou hast destroyed thy land, thou hast slain thy people; the seed of evil-doers shall not be named for ever", but rather be cast out of the grave, while "All the kings of the nations, all of them, sleep in glory, every one in his own house." Herbert Wolf held that the "king of Babylon" was not a specific ruler but a generic representation of the whole line of rulers.
Isaiah 14:12 became a source for the popular conception of the fallen angel motif. Rabbinic Judaism has rejected any belief in rebel or fallen angels. In the 11th century, the Pirkei De-Rabbi Eliezer illustrates the origin of the "fallen angel myth" by giving two accounts, one relates to the angel in the Garden of Eden who seduces Eve, and the other relates to the angels, the who cohabit with the daughters of man (Genesis 6:1–4). An association of Isaiah 14:12–18 with a personification of evil, called the devil, developed outside of mainstream Rabbinic Judaism in pseudepigrapha, and later in Christian writings, particularly with the apocalypses.
As the devil
The metaphor of the morning star that Isaiah 14:12 applied to a king of Babylon gave rise to the general use of the Latin word for "morning star", capitalized, as the original name of the devil before his fall from grace, linking Isaiah 14:12 with Luke 10 ("I saw Satan fall like lightning from heaven") and interpreting the passage in Isaiah as an allegory of Satan's fall from heaven.
Considering pride as a major sin peaking in self-deification, Lucifer () became the template for the devil. As a result, Lucifer was identified with the devil in Christianity and in Christian popular literature, as in Dante Alighieri's Inferno, Joost van den Vondel's Lucifer, and John Milton's Paradise Lost. Early medieval Christianity fairly distinguished between Lucifer and Satan. While Lucifer, as the devil, is fixated in hell, Satan executes the desires of Lucifer as his vassal.
Interpretations
Aquila of Sinope derives the word , the Hebrew name for the morning star, from the verb (to lament). This derivation was adopted as a proper name for an angel who laments the loss of his former beauty. The Christian church fathers – for example Jerome, in his Vulgate – translated this as Lucifer.
Some Christian writers have applied the name "Lucifer" as used in the Book of Isaiah, and the motif of a heavenly being cast down to the earth, to the devil. Sigve K. Tonstad argues that the New Testament War in Heaven theme of Revelation 12, in which the dragon "who is called the devil and Satan [...] was thrown down to the earth", was derived from the passage about the Babylonian king in Isaiah 14. Origen (184/185–253/254) interpreted such Old Testament passages as being about manifestations of the devil. Origen was not the first to interpret the Isaiah 14 passage as referring to the devil: he was preceded by at least Tertullian (), who in his (book 5, chapters 11 and 17) twice presents as spoken by the devil the words of Isaiah 14:14: "I will ascend above the tops of the clouds; I will make myself like the Most High". Though Tertullian was a speaker of the language in which the word was created, "Lucifer" is not among the numerous names and phrases he used to describe the devil. Even at the time of Augustine of Hippo (354–430), a contemporary of the composition of the Vulgate, "Lucifer" had not yet become a common name for the devil.
Augustine's work (5th century) became the major opinion of Western demonology including in the Catholic Church. For Augustine, the rebellion of the Devil was the first and final cause of evil. By this he rejected some earlier teachings about Satan having fallen when the world was already created. Further, Augustine rejects the idea that envy could have been the first sin (as some early Christians believed, evident from sources like the Cave of Treasures in which Satan has fallen because he envies humans and refused to prostrate himself before Adam), since pride ("loving yourself more than others and God") is required to be envious ("hatred for the happiness of others"). He argues that evil came first into existence by the free will of Satan. His attempt to take God's throne is not an assault on the gates of heaven, but a turn to solipsism in which the Devil becomes God in his world. When the king of Babylon uttered his phrase in Isaiah, he was speaking through the sprite of Lucifer, the head of devils. He concluded that everyone who falls away from God are within the body of Lucifer, and is a devil.
Adherents of the King James Only movement and others who hold that Isaiah 14:12 does indeed refer to the Devil have decried the modern translations. An opposing view attributes to Origen the first identification of the "Lucifer" of Isaiah 14:12 with the Devil and to Tertullian and Augustine of Hippo the spread of the story of Lucifer as fallen through pride, envy of God and jealousy of humans.
The 1409 Lollard manuscript titled Lanterne of Light associated Lucifer with the deadly sin of pride.
Protestant theologian John Calvin rejected the identification of Lucifer with Satan or the Devil. He said: "The exposition of this passage, which some have given, as if it referred to Satan, has arisen from ignorance: for the context plainly shows these statements must be understood in reference to the king of the Babylonians." Martin Luther also considered it a gross error to refer this verse to the Devil.
Counter-Reformation writers, like Albertanus of Brescia, classified the seven deadly sins each to a specific Biblical demon. He, as well as Peter Binsfield, assigned Lucifer to the sin of pride.
Gnosticism
Since Lucifer's sin mainly consists of self-deification, some Gnostic sects identified Lucifer with the creator deity in the Old Testament. In the Bogomil and Cathar text Gospel of the Secret Supper, Lucifer is a glorified angel but fell from heaven to establish his own kingdom and became the Demiurge who created the material world and trapped souls from heaven inside matter. Jesus descended to earth to free the captured souls. In contrast to mainstream Christianity, the cross was denounced as a symbol of Lucifer and his instrument in an attempt to kill Jesus.
Latter Day Saint movement
Lucifer is regarded within the Latter Day Saint movement as the pre-mortal name of the Devil. Latter-day Saint theology teaches that in a heavenly council, Lucifer rebelled against the plan of God the Father and was subsequently cast out. The Doctrine and Covenants reads:
After becoming Satan by his fall, Lucifer "goeth up and down, to and fro in the earth, seeking to destroy the souls of men." Members of the Church of Jesus Christ of Latter-day Saints consider Isaiah 14:12 to be referring to both the king of the Babylonians and the Devil.
Other occurrences
Satanism
Luciferianism is a belief structure that venerates the fundamental traits that are attributed to Lucifer. The custom, inspired by the teachings of Gnosticism, usually reveres Lucifer not as the Devil, but as a savior, a guardian or instructing spirit or even the true god as opposed to Jehovah.
In LaVeyan Satanism, Lucifer is described by The Satanic Bible as one of the four crown princes of hell, particularly that of the East, the 'lord of the air', and is called the bringer of light, the morning star, intellectualism, and enlightenment.
Anthroposophy
Rudolf Steiner's writings, which formed the basis for Anthroposophy, characterised Lucifer as a spiritual opposite to Ahriman, with Christ between the two forces, mediating a balanced path for humanity. Lucifer represents an intellectual, imaginative, delusional, otherworldly force which might be associated with visions, subjectivity, psychosis and fantasy. He associated Lucifer with the religious/philosophical cultures of Egypt, Rome and Greece. Steiner believed that Lucifer, as a supersensible Being, had incarnated in China about 3000 years before the birth of Christ.
Freemasonry
Léo Taxil (1854–1907) claimed that Freemasonry is associated with worshipping Lucifer. In what is known as the Taxil hoax, he alleged that leading Freemason Albert Pike had addressed "The 23 Supreme Confederated Councils of the World" (an invention of Taxil), instructing them that Lucifer was God, and was in opposition to the evil god Adonai. Taxil promoted a book by Diana Vaughan (actually written by himself, as he later confessed publicly) that purported to reveal a highly secret ruling body called the Palladium, which controlled the organization and had a satanic agenda. As described by Freemasonry Disclosed in 1897:
Supporters of Freemasonry assert that, when Albert Pike and other Masonic scholars spoke about the "Luciferian path," or the "energies of Lucifer," they were referring to the Morning Star, the light bearer, the search for light; the very antithesis of dark. Pike says in Morals and Dogma, "Lucifer, the Son of the Morning! Is it who bears the Light, and with its splendors intolerable blinds feeble, sensual, or selfish Souls? Doubt it not!" Much has been made of this quote.
Taxil's work and Pike's address continue to be quoted by anti-masonic groups.
In Devil-Worship in France, Arthur Edward Waite compared Taxil's work to today's tabloid journalism, replete with logical and factual inconsistencies.
Charles Godfrey Leland
In a collection of folklore and magical practices supposedly collected in Italy by Charles Godfrey Leland and published in his Aradia, or the Gospel of the Witches, the figure of Lucifer is featured prominently as both the brother and consort of the goddess Diana, and father of Aradia, at the center of an alleged Italian witch-cult. In Leland's mythology, Diana pursued her brother Lucifer across the sky as a cat pursues a mouse. According to Leland, after dividing herself into light and darkness:
Here, the motions of Diana and Lucifer once again mirror the celestial motions of the moon and Venus, respectively. Though Leland's Lucifer is based on the classical personification of the planet Venus, he also incorporates elements from Christian tradition, as in the following passage:
In the several modern Wiccan traditions based in part on Leland's work, the figure of Lucifer is usually either omitted or replaced as Diana's consort with either the Etruscan god Tagni, or Dianus (Janus, following the work of folklorist James Frazer in The Golden Bough).
Gallery
Modern popular culture
See also
Angra Mainyu
Aphrodite
Astarte
Asura
Aurvandil, aka Earendel
Azazil (Angelic name of Satan in Islam)
Azazel
Devil in popular culture
Doctor Faustus, tragic play by Christopher Marlowe
Erlik
Guardian of the Threshold
Inferno, first of the three canticas of Dante's Divine Comedy
Luceafărul, a literary magazine
Luceafărul, a poem by the poet Mihai Eminescu
Lucifer and Prometheus
The Lucifer Effect
Luciform body
Lucis Trust
Phosphorus, the morning star, aka Eosphorus and Heosphorus
Shahar
Notes
References
Further reading
External links
The Editors of Encyclopædia Britannica (2010). Lucifer (classical mythology) . Encyclopaedia Britannica. Encyclopædia Britannica, inc.
Bogomilism
Book of Isaiah
Children of Eos
Christian terminology
Dawn
Deities in the Hebrew Bible
Devils
Diana (mythology)
Fallen angels
Hell (Christianity)
Kings of Babylon
Luciferianism
Vulgate Latin words and phrases
Satan
Planetary gods | Lucifer | Physics | 4,157 |
61,020,200 | https://en.wikipedia.org/wiki/Canite | Canite, also known as caneboard, pinboard or softboard, is a low-density fibreboard panel made from sugar cane fibres. It is easy to handle, lightweight and relatively durable. Because of its low environmental footprint it is considered a sustainable building product. It can be used without finish, painted, or rendered with natural lime-based products. It is commonly used for
Interior wall and ceiling lining
Pin boards and bulletin boards
Office partitions
Protective covering boards
Sound insulation and reflected sound reduction
Door fillings
Stucco base
Soundproofing under floorboards
Fire lighter (when saturated with kerosene)
In Australia, canite is commonly sold in 2400 x 1200 mm panels. They are typically 10–13 mm thick, with a density of 350 kg/m3.
References
Building materials | Canite | Physics,Engineering | 160 |
14,457,045 | https://en.wikipedia.org/wiki/Ald%20%28unit%29 | Ald is an obsolete Mongolian measure equal to the average human male's armspan (length between a male's outstretched arms). An ald is therefore approximately equal to .
See also
Mongolian units
Culture of Mongolia
Units of length
Human-based units of measurement
Obsolete units of measurement | Ald (unit) | Mathematics | 59 |
43,004,608 | https://en.wikipedia.org/wiki/Richard%20Gibbs%20%28biologist%29 | Richard Alexander Gibbs, , is an Australian geneticist. He is currently the Wofford Cain Chair and Professor of Molecular and Human Genetics at Baylor College of Medicine in Houston, Texas.
In 1996, he founded the Human Genome Sequencing Center at BCM, which was one of five worldwide sites selected to complete the final phase of the Human Genome Project.
References
External links
Richard A. Gibbs, Ph.D. (Department of Molecular and Human Genetics, Baylor College of Medicine)
1950s births
Living people
Australian geneticists
Companions of the Order of Australia
University of Melbourne alumni
Australian expatriates in the United States
Human Genome Project scientists
Members of the National Academy of Medicine | Richard Gibbs (biologist) | Engineering | 134 |
60,096,155 | https://en.wikipedia.org/wiki/Asma%20Ismail | Academician Professor Emerita Datuk Dr Asma binti Ismail, FASc is a Malaysian academic and molecular biologist. She is the first female Vice-Chancellor (VC) of Universiti Sains Malaysia (USM) appointed in 2016 and the first female VC of Universiti Sains Islam Malaysia (USIM) in 2012. Asma is also Malaysia’s first female Director-General of Higher Education, first female President of Academy of Sciences Malaysia (2016-2019), first female to be appointed as the Chairperson of the Malaysian Qualifications Agency (MQA) (2019-2021) and the first woman to be the National Science Advisor to the Prime Minister and to the country. In addition, she was elected to the Academy of Sciences Malaysia in 2003, The Academy of Sciences for the Developing World (TWAS) in 2010, The Islamic World Academy of Sciences in 2016, and as an Honorary Member of the Iranian Academy of Medical Sciences in 2017.
She has been appointed as the Vice-Chancellor and Chief Executive Officer of IMU University as of 1 August 2024.
Education
Asma earned her BSc in Biology from the University of Nevada, Reno. She then received her MSc in Microbiology from Indiana University, Bloomington and a Ph.D specialising in cellular and molecular biology from the University of Nevada, Reno.
Career
University of Science Malaysia
Asma started her career as a lecturer at the Department of Medical Microbiology and Parasitology, School of Medical Sciences, University of Science Malaysia in 1986. In 1989, she was appointed visiting scientist at Tokyo University and Visitor Fellow at Medical College, St Bartholomew Hospital in London in 1992. In 1993, she was promoted to associate professor and served as Deputy Dean of Administration in 1994. She was promoted to full professor in 2000 and was appointed Deputy Dean of Research.
During her tenure at USM, she has held numerous positions including Director of Center for Innovation and Technology Development, USM (2001); Founder Director, Molecular Medicine Research Institute (INFORM) (2003) and is the first woman in USM to hold the position of Deputy Vice-Chancellor (Research and Innovation).
Ministry of Higher Education and Beyond
Asma became the Director-General of Higher Education at the Ministry of Higher Education Malaysia in 2014. She has played a vital role in progressing the higher education system including the establishment of the prestigious National Academic Award (Anugerah Akademik Negara), the establishment of Research Universities in Malaysia and in developing and implementing The Malaysian Education Blueprint (Higher Education) 2013 to 2025. She is currently involved in the rewriting of the Higher Education blueprint 2026 to 2035 and is a member of the Higher Education Advisory Panel for financial sustainability of universities under the Ministry of Higher Education (MOHE).
Research
Asma has worked on a rapid diagnostic test for typhoid called TYPHIDOT, which was advocated by WHO. She has published more 130 papers locally and abroad.
Asma was elected to the Academy of Sciences Malaysia in 2003. She also was elected as a member at The Academy of Sciences for the Developing World in 2010 and The Islamic World Academy of Sciences in 2016. She was elected as Honorary Member of the Iranian Academy of Medical Sciences in 2017, and as a Member of the College of Fellows, Keele University in 2018. She was invited to become an Honourable member of International Board of Advisors, Chandigarh University, India and as a Governing Advisory Board Member for Ritsumeikan Asia Pacific University, Japan.
Honours
Honours of Malaysia
:
Commander of the Order of Meritorious Service (PJN) - Datuk (2016)
:
Knight Companion of the Order of Loyalty to the Royal House of Kedah (DSDK) – Dato' (2013)
:
Knight Commander of the Order of the Crown of Perlis (DPMP) – Dato' (2018)
Awards
Asma was awarded as “Tokoh Akademik Negara “ or National Academic Laureate in 2022, “Tokoh Maulidul Rasul” (national level) in 2019 and “Tokoh Srikandi” National Award (Academic) in 2018. Other awards and recognitions include National Young Scientist Award, National Innovation Award and was named in January 2023 by Forbes Asia magazine as among the Top 50 women over 50 from Asia Pacific that had reached new heights in contributing to the field of higher education, research and innovation as well as policy in the Science, Technology, Innovation and Economy locally and abroad and for inspiring the next generation.
She also received the Honorary Doctor of Science from the University of Glasgow (2013), the Thomas Hard Benton Mural Medallion by the Indiana University (2015), the Honorary Doctorate from Keele University and Honorary LLD from Kyoto University of Foreign Studies in 2017.
References
1958 births
Living people
Malaysian biologists
Molecular biologists
University of Nevada, Reno alumni
Indiana University Bloomington alumni
Commanders of the Order of Meritorious Service | Asma Ismail | Chemistry | 996 |
51,537,337 | https://en.wikipedia.org/wiki/Iota2%20Normae | {{DISPLAYTITLE:Iota2 Normae}}
ι2 Normae, Latinised as Iota2 Normae, is a single, blue-white star located in the southern constellation of Norma. It is positioned to the west of Rigil Kentaurus but can be difficult to spot against the Milky Way. It is faintly visible to the naked eye with an apparent visual magnitude of +5.57. Measuring its parallax reveals it is located away from the sun. At that distance, the visual magnitude is diminished by an interstellar extinction factor of 0.24 due to intervening dust. The radial velocity of this star is zero, indicating it is neither moving toward nor away from the Sun.
Iota2 Normae is a B-type main-sequence star with a stellar classification of B9.5 V. It is larger than the Sun with 2.6 times the mass of the Sun and about 3.1 times the Sun's radius. The star is estimated to be 257 million years old and is spinning with a projected rotational velocity of 111 km/s. It is radiating approximately 40 times the Sun's luminosity from its photosphere at an effective temperature of 10,593 Kelvin.
References
External links
Alcyone page
Normae, Iota2
Norma (constellation)
Normae, Iota2
Durchmusterung objects
144480
5994
079153 | Iota2 Normae | Astronomy | 290 |
8,826,171 | https://en.wikipedia.org/wiki/List%20of%20substances%20used%20in%20rituals | This page lists substances used in ritual context.
Psychoactive substances may be illegal to obtain, while non-psychoactive substances are legal, generally.
Psychoactive use
This sections lists entheogens; drugs that are consumed for their intoxicating effect in combination with spiritual practice.
Hallucinogens used in rituals
This is a list of species and genera that are used as entheogens or are used in an entheogenic concoction (such as ayahuasca). For ritualistic use they may be classified as hallucinogens. The active principles and historical significance of each are also listed to illustrate the requirements necessary to be categorized as an entheogen. The psychoactive substances are usually classified as soft drugs in terms of drug harmfulness.
Animal
Mushroom
Plant
Chemicals
Many man-made chemicals with little human history have been recognized to catalyze intense spiritual experiences, and many synthetic entheogens are simply slight modifications of their naturally occurring counterparts. Some synthetic substances like 4-AcO-DMT are thought to be prodrugs that metabolize into psychoactive substances that have been used as entheogens. While synthetic DMT and mescaline are reported to have identical entheogenic qualities as extracted or plant-based sources, the experience may wildly vary due to the lack of numerous psychoactive alkaloids that constitute the material. This is similar to how isolated THC produces very different effects than an extract that retains the many cannabinoids of the plant such as cannabidiol and cannabinol. A pharmaceutical version of the entheogenic brew ayahuasca is called Pharmahuasca.
Prodrugs
This page lists non-psychedelic psychoactive substances which are consumed in ritual contexts for their consciousness-altering effects. Non-psychoactive consumption like symbolic ingestion of psychoactive substances is not mentioned here.
Non-hallucinogenic substances used in rituals
This is a list of psychoactive substances which are consumed in ritual contexts for their consciousness-altering effects. Some of these drugs are classified as hard drugs in terms of drug harmfulness.
Plant
The plant parts are listed to prevent accidents. For example, kava roots should always be used because the leaves of the plant are known to cause hepatoxicity and death.
Alcohol
Chemicals
Poly drug use
Alternative medicine
Animal
Complements to psychoactive substances
Sober use
Non-psychoactive substances
Psychoactive substances
Shown in the table below, Aztec tobacco, morning glories, and Syrian rue (also listed in the table), and cacao beans are (mildly) psychoactive when consumed.
Psychedelic substances used in sober rituals
Flora
Non-psychedelic substances used in sober rituals
Alcohol
See also
Entheogenic drugs and the archaeological record
Ethnobotany
God in a Pill?
List of Acacia species known to contain psychoactive alkaloids
List of plants used for smoking
N,N-Dimethyltryptamine
Psilocybin mushrooms
Psychoactive cacti
Psychoactive plant
References
Works cited
Internet Archive EPub file – freely downloadable (37Mb)
Databases
USDA online database compiled from:
Further reading
Biological sources of psychoactive drugs
Hallucinations
Rituals
Comparison of psychoactive substances
Religious rituals | List of substances used in rituals | Chemistry | 651 |
22,876,971 | https://en.wikipedia.org/wiki/Radiation-induced%20lung%20injury | Radiation-induced lung injury (RILI) is a general term for damage to the lungs as a result of exposure to ionizing radiation. In general terms, such damage is divided into early inflammatory damage (radiation pneumonitis) and later complications of chronic scarring (radiation fibrosis). Pulmonary radiation injury is an unavoidable risk of radiation therapy administered to treat thoracic or lung cancer.
Symptoms and signs
The lungs are a radiosensitive organ, and radiation pneumonitis can occur leading to pulmonary insufficiency and death (100% after exposure to 50 gray of radiation) in a few months. Radiation pneumonitis is characterized by:
Loss of epithelial cells
Edema
Inflammation
Occlusions airways, air sacs and blood vessels
Fibrosis
Symptoms of radiation pneumonitis include: fever, cough, chest congestion, shortness of breath, chest pain
Diagnosis
High resolution CT thorax
Treatment
“The Canadian Cancer society mentions these things that help to manage radiation,
Your healthcare team may recommend medicines to treat radiation pneumonitis, such as:
decongestants
cough suppressants
bronchodilators
corticosteroids to reduce inflammation
oxygen therapy
You can also try the following to help manage symptoms:
Rest if you feel short of breath.
Drink more fluids and use a cool-air vaporizer or humidifier to keep the air moist.
Use an extra pillow to raise your head and upper body while resting or sleeping.
Avoid the outdoors on hot, humid days or very cold days (which can irritate the lungs).
Wear light, loose-fitting tops and avoid anything tight around the neck, such as ties or shirt collars.“
For more information go to their website, as they have accurate information.“More Info”
See also
Radiation poisoning
References
Further reading
External links
PubMed
Radiation health effects
Radiation therapy
Lung diseases due to external agents | Radiation-induced lung injury | Chemistry,Materials_science | 393 |
1,052,019 | https://en.wikipedia.org/wiki/Mundane%20astrology | Mundane astrology, also known as political astrology, is the branch of astrology dealing with politics, the government, and the laws governing a particular nation, state, or city. The name derives name from the Latin term , 'world'.
Certain countries have astrological charts (or horoscopes) just like a person is said to in astrology; for example, the chart for the United States is widely thought to be sometime during the day of July 4, 1776, for this is the exact day that the Declaration of Independence was signed and made fully official, thus causing the "birth" of the United States as a nation. Indeed, July 4 is a major national holiday in America and unequivocally thought of as the "birthday" of the entire nation.
History
Mundane astrology is widely believed by astrological historians to be the most ancient branch of astrology. Early Babylonian astrology was exclusively concerned with mundane astrology, being geographically oriented, specifically applied to countries cities and nations, and almost wholly concerned with the welfare of the state and the king as the governing head of the nation. Astrological practices of divination and planetary interpretation have been used for millennia to answer political questions, but only with the gradual emergence of horoscopic astrology, from the sixth century BC, did astrology develop into the two distinct branches of mundane astrology and natal astrology.
Techniques and principles
Astrologically, the affairs of a nation are judged from the horoscope set up at the time of its official inauguration or the birth chart of its leader, or various phenomena such as eclipses, lunations, great conjunctions, planetary stations, comets and ingresses.
The techniques of the subject were discussed in detail in the 2nd century work of the Alexandrian astronomer Ptolemy, who outlined its principles in the second book of his Tetrabiblos. Ptolemy set this topic before his discussion of individual birth charts because he argued that the astrological assessment of any 'particular' individual must rest upon prior knowledge of the 'general' temperament of their ethnic type; and that the circumstances of individual lives are subsumed, to some extent, within the fate of their community. The third chapter of his work offers an association between planets, zodiac signs and the national characteristics of 73 nations. It concludes with three assertions which act as core principles of mundane astrology:
Each of the fixed stars has familiarity with the countries attributed to the sign of its ecliptic rising.
The time of the first founding of a city (or nation) can be used in a similar way to an individual horoscope, to astrologically establish the characteristics and experiences of that city. The most significant considerations are the regions of the zodiac which mark the place of the Sun and Moon, and the four angles of the chart – in particular the ascendant.
If the time of the foundation of the city or nation is not known, a similar use can be made of the horoscope of whoever holds office or is king at the time, with particular attention given to the midheaven of that chart.
Practice
The first English astrologer for whom we have evidence of astrological practice is Richard Trewythian, whose notebook is largely concerned with mundane astrology. He constructed horoscopes for the Sun's ingress into Aries over thirty years, and recorded general predictions for twelve of those years between 1430 and 1458. His notebooks demonstrate how he recorded the logic for his conclusions:
He also made several predictions concerning the king (Henry VI), such as one he made in 1433 where he noted: "it seems that the king will be sick this year because Saturn is lord of the tenth house".
Notes
References
Works cited
External links
17th Century study in the Ancient Art of Mundane Astrology hosted by Skyscript (accessed 1 July 2012). The complete fourth book of William Ramesey's Astrologiae Restaurata, 'Astrology Restored' (London, 1653), edited and annotated by Steven Birchfield (1.43MB). The Fourth book is entitled Astrologia Munda, 'Mundane Astrology' - said by Birchfield to be the closest thing we have to an accessible textbook on traditional mundane astrology.
Astrology | Mundane astrology | Astronomy | 868 |
24,507,557 | https://en.wikipedia.org/wiki/Gymnopilus%20thiersii | Gymnopilus thiersii is a species of mushroom in the family Hymenogastraceae.
Description
This species is nearly identical to Gymnopilus luteofolius, but differs in having different context colors and dextrinoid spores. It contains the hallucinogenic drugs psilocybin and psilocin, and stains blue-green where damaged. The type location for G. thiersii is Wunderlich Park in San Mateo County, California.
See also
List of Gymnopilus species
External links
Gymnopilus thiersii at Index Fungorum
Original species description
thiersii
Fungus species | Gymnopilus thiersii | Biology | 132 |
367,692 | https://en.wikipedia.org/wiki/EMERGCON | EMERGCON (emergency condition) is a state of readiness that is separate from DEFCON, or defense readiness condition used by the United States, in that it incorporates civilian measures in addition to the DEFCON military measures.
Overview
Generally, EMERGCONs are a state of readiness following an ICBM (intercontinental ballistic missile) attack. Other forces go to DEFCON 1 during EMERGCONs. There are two types of EMERGCONs:
Defense Emergency: A major hostile attack on United States and/or allied forces overseas, and/or an overt action made against the United States. This must be confirmed by a unified commander or higher authority.
Air Defense Emergency: A major hostile attack by aircraft or missiles seems probable, is imminent, or is taking place on the continental United States, Canada, or Greenland. This declaration is made by the Commander of the North American Aerospace Defense Command (NORAD).
Although the United States military has gone into defense readiness at various times (such as the Cuban Missile Crisis), it has never had a major EMERGCON.
See also
DEFCON
LERTCON
REDCON
Alert state
Information Operations Condition
References
Alert measurement systems
Military terminology of the United States | EMERGCON | Technology | 244 |
23,626,261 | https://en.wikipedia.org/wiki/Manchester%20Hydraulic%20Power | Manchester's Hydraulic Power system was a public hydraulic power network supplying energy across the city of Manchester via a system of high-pressure water pipes from three pumping stations from 1894 until 1972. The system, which provided a cleaner and more compact alternative to steam engines, was used to power workshop machinery, lifts, cranes and a large number of cotton baling presses in warehouses as it was particularly useful for processes that required intermittent power. It was used to wind Manchester Town Hall clock, pump the organ at Manchester Cathedral and raise the safety curtain at Manchester Opera House in Quay Street. A large number of the lifts and baling presses that used the system had hydraulic packings manufactured by John Talent and Co.Ltd. who had a factory at Ashworth Street, just off the Bury New Rd. close to the Salford boundary.
Manchester Corporation opened its first pumping station in 1894, following pioneering schemes in Kingston upon Hull and London. The scheme was a success and additional pumping stations to cope with the demand for power were added in 1899 and 1909. Modernisation started in the 1920s, when the original steam pumps were replaced by electric motors at two pumping stations. The greatest volume of water was supplied in the 1920s, although the length of the water mains continued to increase until 1948. Usage started to decrease in the 1930s, and the first pumping station closed in 1939. By the 1960s, there were serious concerns about the state of some of the equipment and corrosion in the high-pressure mains, and in 1968 the corporation announced its intent to switch the system off, which it did at the end of 1972.
The grade II listed pumping station built in Baroque style at Water Street has a new life as part of the People's History Museum, while one of its pump sets has been restored and is displayed at the Museum of Science and Industry, where it is part of a larger display about hydraulic power.
History
While Joseph Bramah had registered a patent for the distribution of high-pressure water via a ring main at the London Patent Office on 29 April 1812, and engineer William Armstrong had installed hydraulic systems for single customers from the 1840s, the first installation of a public hydraulic power network became operational in Kingston upon Hull in 1876. Edward B. Ellington was responsible, and created the General Hydraulic Power Company, from which developed the London Hydraulic Power Company. With the technology tested, and Ellington's model of marketing hydraulic power as a public utility having proved successful, Manchester Corporation obtained an act of Parliament authorising it to build a network to distribute hydraulic power to the city in 1891.
The corporation had the advantage over a private company in that it did not have to apply for permission to dig up the streets to install the network of high-pressure water mains. The pumping station was situated on Whitworth Street West, between Oxford Road railway station and the Rochdale Canal. Its working pressure was set at , much higher than the of the London system, because it was expected that much of the power would be used for baling cotton, and the extra pressure was dictated by the design of existing baling equipment. Pressure was supplied by six triple-expansion steam engines, rated at each, and was maintained by two hydraulic accumulators, with pistons of diameter, a stroke of , and loaded with 127 tonnes. The equipment was supplied by Ellington's company. Installation was completed by 1894, and by 1895 there were 12 miles (19 km) of hydraulic pipes under the city streets, providing power for 247 machines.
Demand was high, and a second pumping station commenced operation on 6 July 1899. It was constructed at Pott Street in Ancoats, close to the Rochdale Canal, and had four pumping engines and two accumulators. The number of engines was increased to seven, six of and one of . A third pumping station was soon required and was constructed between Water Street and the River Irwell. It had two accumulators, and six steam engines. Coal for the engines was delivered by boat, and it began operating on 14 October 1909. Although all three pumping stations were situated beside waterways, its water supply was obtained from boreholes. The borehole at Whitworth Street was deep, and water at all three was raised by compressed air delivery systems, which lasted until 1948, when they were superseded by submersible pumps. By the 1930s, the system had grown to 35 miles (56 km) of pipes working some 2400 machines.
Replacement of the steam engines began in 1922, starting at Whitworth Street. Four pumping engines were removed and replaced by electrically driven centrifugal pumps. The work was completed by 1924. The following year, the remaining pumps were retained, but their steam cylinders were removed, and the flywheels replaced by a helical gear drive, to connect the pumps to electric motors. These were variable speed direct current devices, and a motor converter set had to be installed, to provide the low voltage DC supply from the incoming high voltage alternating current supply. The motor converter set was built in 1914, and was second-hand. The pumps at the Water Street station were converted to electrical operation in a similar manner soon afterwards.
Decline
Demand for hydraulic power began to fall in the 1930s, as electric power became more popular, but although the number of customers dropped, the supply pipes were extended until the system reached its maximum length of in 1948. The Pott Street pumping station closed in 1939. By the 1960s, the motor converter set was 50 years old, and most of the pumps were older still. The effects of corrosion on high-pressure water mains were also a cause for concern. In 1964, a similar system in Glasgow, opened a year later than the Manchester system using water at was switched off and some of its equipment was used to refit Whitworth Street station. The two centrifugal pumps and a converted steam pump were removed and replaced by two high-speed reciprocating pumps from Glasgow. Although not ideal for a diminishing network, because they were fixed speed devices, they provided a back-up system if there were problems at Water Street.
By 1968, the length of pressure main was reduced to , and the Waterworks Committee gave notice to all 120 customers that the system would be shut down in four years' time. By that time, the stations were supplying 2 million gallons (9.1 Megalitres) of pressurised water per year, down from the 360 million gallons (1,600 Ml) supplied when the system was at its peak. The system was switched off on 28 December 1972, when the Chairman of the Waterworks Committee stopped the pumps at a ceremony.
Pumping stations
The three hydraulic power stations were located at Whitworth Street West, Pott Street and Water Street.
The Whitworth Street station was opened in 1894 on the banks of the Rochdale Canal, between the canal and Oxford Road railway station, immediately to the west of St Mary's Hospital. It was the first to be upgraded to electrical operation, but was little used after 1964, as it held equipment bought from Glasgow, which was only used as a backup. After the system closed, its contents were sold for scrap and the building was demolished.
Pott Street station was in Ancoats and opened in 1899. It was not electrified, and closed in 1939. Its site and the site at Pott Street have disappeared under the car park at the Central Retail Park in Ancoats.
The third station at Water Street, on the banks of the River Irwell was completed in 1909, and was designed in Baroque style by architect Henry Price. The station was electrified in 1925, and was the location for the closing ceremony at the end of 1972. After closure, it was used as a workshop by the City College. In 1992, it was designated a grade II listed structure, and since 1994 has been part of the People's History Museum complex. One of the pump sets has been moved to the Museum of Science and Industry, where it has been restored to working order and forms part of a display about hydraulic power. The pumps were made by the Manchester firm of Galloways. It is now referred to as the Bridge Street station, because the part of Water Street on which it stood has disappeared in the redevelopment of the area.
See also
London Hydraulic Power Company
Liverpool Hydraulic Power Company
Bibliography
References
External links
People's History Museum
Museum of Science & Industry: Water Power
Hydraulic power in London from Subterranea Britannica including photographs.
Hydraulics
Subterranea of the United Kingdom
Utilities of the United Kingdom | Manchester Hydraulic Power | Physics,Chemistry | 1,731 |
7,278,018 | https://en.wikipedia.org/wiki/Paxillus%20involutus | Paxillus involutus, also known as the brown roll-rim or the common roll-rim, is a basidiomycete fungus that is widely distributed across the Northern Hemisphere. It has been inadvertently introduced to Australia, New Zealand, South Africa, and South America, probably transported in soil with European trees. Various shades of brown in colour, the fruit body grows up to high and has a funnel-shaped cap up to wide with a distinctive inrolled rim and decurrent gills that may be pore-like close to the stipe. Although it has gills, it is more closely related to the pored boletes than to typical gilled mushrooms. It was first described by Pierre Bulliard in 1785, and was given its current binomial name by Elias Magnus Fries in 1838. Genetic testing suggests that Paxillus involutus may be a species complex rather than a single species.
A common mushroom of deciduous and coniferous woods and grassy areas in late summer and autumn, Paxillus involutus forms ectomycorrhizal relationships with a broad range of tree species. These benefit from the symbiosis as the fungus reduces their intake of heavy metals and increases resistance to pathogens such as Fusarium oxysporum. Previously considered edible and eaten widely in Eastern and Central Europe, it has since been found to be dangerously poisonous, after being responsible for the death of German mycologist Julius Schäffer in 1944. It had been recognized as causing gastric upsets when eaten raw, but was more recently found to cause potentially fatal autoimmune hemolysis, even in those who had consumed the mushroom for years without any other ill effects. An antigen in the mushroom triggers the immune system to attack red blood cells. Serious and commonly fatal complications include acute kidney injury, shock, acute respiratory failure, and disseminated intravascular coagulation.
Taxonomy and naming
The brown roll-rim was described by French mycologist Pierre Bulliard in 1785 as Agaricus contiguus, although the 1786 combination Agaricus involutus of August Batsch is taken as the first valid description. James Bolton published a description of what he called Agaricus adscendibus in 1788; the taxonomical authority Index Fungorum considers this to be synonymous with P. involutus. Additional synonyms include Omphalia involuta described by Samuel Frederick Gray in 1821, and Rhymovis involuta, published by Gottlob Ludwig Rabenhorst in 1844. The species gained its current binomial name in 1838 when the 'father of mycology', Swedish naturalist Elias Magnus Fries erected the genus Paxillus, and set it as the type species. The starting date of fungal taxonomy had been set as January 1, 1821, to coincide with the date of Fries' works, which meant that names coined earlier than this date required sanction by Fries (indicated in the name by a colon) to be considered valid. It was thus written Paxillus involutus (Batsch:Fr.) Fr. A 1987 revision of the International Code of Botanical Nomenclature set the starting date at May 1, 1753, the date of publication of Linnaeus' seminal work, the Species Plantarum. Hence the name no longer requires the ratification of Fries' authority.
The genus was later placed in a new family, Paxillaceae, by French mycologist René Maire who held it to be related to both agarics and boletes. Although it has gills rather than pores, it has long been recognised as belonging to the pored mushrooms of the order Boletales rather than the traditional agarics. The generic name is derived from the Latin for 'peg' or 'plug', and the specific epithet involutus, 'inrolled', refers to the cap margin. Common names include the naked brimcap, poison paxillus, inrolled pax, poison pax, common roll-rim, brown roll-rim, and brown chanterelle. Gray called it the "involved navel-stool" in his 1821 compendium of British flora.
Studies of the ecology and genetics of Paxillus involutus indicate that it may form a complex of multiple similar-looking species. In a field study near Uppsala, Sweden, conducted from 1981 to 1983, mycologist Nils Fries found that there were three populations of P. involutus unable to breed with each other. One was found under conifers and mixed woodlands, while the other two were found in parklands, associated with nearby birch trees. He found that the first group tended to produce single isolated fruit bodies which had a thinner stipe and cap which was less inrolled at the margins, while the fruit bodies of the other two populations tended to appear in groups, and have thicker stipes, and caps with more inrolled and sometimes undulating margins. There were only general tendencies and he was unable to detect any consistent macroscopic or microscopic features that firmly differentiate them. A molecular study comparing the DNA sequences of specimens of Paxillus involutus collected from various habitats in Bavaria found that those collected from parks and gardens showed a close relationship with the North American species P. vernalis, while those from forests were allied with P. filamentosus. The authors suggested the park populations may have been introduced from North America. A multi-gene analysis of European isolates showed that P. involutus sensu lato (in the loose sense) could be separated into four distinct, genetically isolated lineages corresponding to P. obscurosporus, P. involutus sensu stricto (in the strict sense), P. validus, and a fourth species that has not yet been identified. Changes in host range have occurred frequently and independently among strains within this species complex.
Description
Resembling a brown wooden top, the epigeous (aboveground) fruit body may be up to high. The cap, initially convex then more funnel-shaped (infundibuliform) with a depressed centre and rolled rim (hence the common name), may be reddish-, yellowish- or olive-brown in colour and typically wide; the cap diameter does not get larger than . The cap surface is initially downy and later smooth, becoming sticky when wet. The cap and cap margin initially serve to protect the gills of young fruit bodies: this is termed pilangiocarpic development. The narrow brownish yellow gills are decurrent and forked, and can be peeled easily from the flesh (as is the case with the pores of boletes). Gills further down toward the stipe become more irregular and anastomose, and can even resemble the pores of bolete-type fungi. The fungus darkens when bruised and older specimens may have darkish patches. The juicy yellowish flesh has a mild to faintly sour or sharp odor and taste, and has been described as well-flavored upon cooking. Of similar colour to the cap, the short stipe measures some 3–6 cm tall and 1–3 wide, can be crooked, and tapers toward the base.
The spore print is brown, and the dimensions of the ellipsoid (oval-shaped) spores are 7.5–9 by 5–6 μm.
The hymenium has cystidia both on the gill edge and face (cheilo- and pleurocystidia respectively), which are slender and filament-like, typically measuring 40–65 by 8–10.5 μm.
Similar species
The brownish colour and funnel-like shape of P. involutus can lead to its confusion with several species of Lactarius, many of which have some degree of toxicity themselves. The lack of a milky exudate distinguishes it from any milk cap. One of the more similar is L. turpis, which presents a darker olive colouration. The related North American Paxillus vernalis has a darker spore print, thicker stipe and is found under aspen, whereas the closer relative P. filamentosus is more similar in appearance to P. involutus. A rare species that grows only in association with alder, P. filamentosus can be distinguished from it by the pressed-down scales on the cap surface that point towards the cap margin, a light yellow flesh that bruises only slightly brown, and deep yellow-ochre gills that do not change colour upon injury
The most similar species are two once thought to be part of P. involutus in Europe. Paxillus obscurisporus (originally obscurosporus) has larger fruit bodies than P. involutus, with caps up to wide whose margins tend to unroll and flatten with age, and a layer of cream-coloured mycelia covering the base of its tapered stipe. P. validus, also known only from Europe, has caps up to wide with a stipe that is more or less equal in width throughout its length. Found under broadleaved trees in parks, it can be reliably distinguished from P. involutus (and other Paxillus species) by the presence of crystals up to 2.5 μm long in the rhizomorphs, as the crystals found in rhizomorphs of other Paxillus species do not exceed 0.5 μm long.
Other similar species include Phylloporus arenicola, Tapinella atrotomentosa, and Tapinella panuoides.
Ecology, distribution and habitat
Paxillus involutus forms ectomycorrhizal relationships with a number of coniferous and deciduous tree species. Because the fungus has somewhat unspecialized nutrient requirements and a relatively broad host specificity, it has been frequently used in research and seedling inoculation programs. There is evidence of the benefit to trees of this arrangement: in one experiment where P. involutus was cultivated on the root exudate of red pine (Pinus resinosa), the root showed markedly increased resistance to pathogenic strains of the ubiquitous soil fungus Fusarium oxysporum. Seedlings inoculated with P. involutus also showed increased resistance to Fusarium. Thus P. involutus may be producing antifungal compounds which protect the host plants from root rot. Paxillus involutus also decreases the uptake of certain toxic elements, acting as a buffer against heavy metal toxicity in the host plant. For example, the fungus decreased the toxicity of cadmium and zinc to Scots pine (Pinus sylvestris) seedlings: even though cadmium itself inhibits ectomycorrhiza formation in seedlings, colonization with P. involutus decreases cadmium and zinc transport to the plant shoots and alters the ratio of zinc transported to the roots and shoots, causing more cadmium to be retained in the roots of the seedlings rather than distributed through its entire metabolism. Evidence suggests that the mechanism for this detoxification involves the cadmium binding to the fungal cell walls, as well as accumulating in the vacuolar compartments. Further, ectomycorrhizal hyphae exposed to copper or cadmium drastically increase production of a metallothionein—a low molecular weight protein that binds metals.
The presence of Paxillus involutus is related to much reduced numbers of bacteria associated with the roots of Pinus sylvestris. Instead bacteria are found on the external mycelium. The types of bacteria change as well; a Finnish study published in 1997 found that bacterial communities under P. sylvestris without mycorrhizae metabolised organic and amino acids, while communities among P. involutus metabolised the sugar fructose. Paxillus involutus benefits from the presence of some species of bacteria in the soil it grows in. As the fungus grows it excretes polyphenols, waste products that are toxic to itself and impede its growth, but these compounds are metabolised by some bacteria, resulting in increased fungal growth. Bacteria also produce certain compounds such as citric and malic acid, which stimulate P. involutus.
Highly abundant, the brown roll-rim is found across the Northern Hemisphere, Europe and Asia, with records from India, China, Japan, Iran, and Turkey's eastern Anatolia. It is equally widely distributed across northern North America, extending north to Alaska, where it has been collected from tundra near Coldfoot in the interior of the state. In southwestern Greenland, P. involutus has been recorded under the birch species Betula nana, B. pubescens and B. glandulosa. The mushroom is more common in coniferous woods in Europe, but is also closely associated with birch (Betula pendula). Within woodland, it prefers wet places or boggy ground, and avoids calcareous (chalky) soils. It has been noted to grow alongside Boletus badius in Europe, and Leccinum scabrum and Lactarius plumbeus in the Pacific Northwest region of North America. There it is found in both deciduous and coniferous woodland, commonly under plantings of white birch (Betula papyrifera) in urban areas. It is one of a small number of fungal species which thrive in Pinus radiata plantations planted outside their natural range. A study of polluted Scots pine forest around Oulu in northern Finland found that P. involutus became more abundant in more polluted areas while other species declined. Emissions from pulp mills, fertiliser, heating and traffic were responsible for the pollution, which was measured by sulfur levels in the pine needles.
Paxillus involutus can be found growing on lawns and old meadows throughout its distribution. Fruit bodies are generally terrestrial, though they may be found on woody material around tree stumps. They generally appear in autumn and late summer. In California, David Arora discerned a larger form associated with oak and pine which appears in late autumn and winter, as well as the typical form that is associated with birch plantings and appears in autumn. Several species of flies and beetles have been recorded using the fruit bodies to rear their young. The mushroom can be infected by Hypomyces chrysospermus, or bolete eater, a mould species that parasitises Boletales members. Infection results in the appearance of a whitish powder that first manifests on the pores, then spreads over the surface of the mushroom, becoming golden yellow to reddish-brown in maturity.
Australian mycologist John Burton Cleland noted it occurring under larch (Larix), oak, pine, birch and other introduced trees in South Australia in 1934, and it has subsequently been recorded in New South Wales, Victoria (where it was found near Betula and Populus) and Western Australia. It has been recorded under introduced birch (Betula) and hazel (Corylus) in New Zealand. Mycologist Rolf Singer reported a similar situation in South America, with the species recorded under introduced trees in Chile. It is likely to have been transported to those countries in the soil of imported European trees.
Toxicity
Paxillus involutus was widely eaten in Central and Eastern Europe until World War II, although English guidebooks did not recommend it. In Poland, the mushroom was often eaten after pickling or salting. It was known to be a gastrointestinal irritant when ingested raw but had been presumed edible after cooking. Questions were first raised about its toxicity after German mycologist Julius Schäffer died after eating it in October 1944. About an hour after he and his wife ate a meal prepared with the mushrooms, Schäffer developed vomiting, diarrhea, and fever. His condition worsened to the point where he was admitted to hospital the following day and developed kidney failure, perishing after 17 days.
In the mid-1980s, Swiss physician René Flammer discovered an antigen within the mushroom that stimulates an autoimmune reaction causing the body's immune cells to consider its own red blood cells as foreign and attack them. Despite this, it was not until 1990 that guidebooks firmly warned against eating P. involutus, and one Italian guidebook recommended it as late as 1998. The relatively rare immunohemolytic syndrome occurs following the repeated ingestion of Paxillus mushrooms. Most commonly it arises when the person has ingested the mushroom for a long period of time, sometimes for many years, and has shown mild gastrointestinal symptoms on previous occasions. The Paxillus syndrome is better classed as a hypersensitivity reaction than a toxicological reaction as it is caused not by a genuinely poisonous substance but by the antigen in the mushroom. The antigen is still of unknown structure but it stimulates the formation of IgG antibodies in the blood serum. In the course of subsequent meals, antigen-antibody complexes are formed; these complexes attach to the surface of blood cells and eventually lead to their breakdown.
Poisoning symptoms are rapid in onset, consisting initially of vomiting, diarrhea, abdominal pain, and associated decreased blood volume. Shortly after these initial symptoms appear, hemolysis develops, resulting in reduced urine output, hemoglobin in the urine or outright absence of urine formation, and anemia. Medical laboratory tests consist of testing for the presence of increasing bilirubin and free hemoglobin, and falling haptoglobins. Hemolysis may lead to numerous complications including acute kidney injury, shock, acute respiratory failure, and disseminated intravascular coagulation. These complications can cause significant morbidity with fatalities having been reported.
There is no antidote for poisoning, only supportive treatment consisting of monitoring complete blood count, renal function, blood pressure, and fluid and electrolyte balance and correcting abnormalities. The use of corticosteroids may be a useful adjunct in treatment, as they protect blood cells against hemolysis, thereby reducing complications. Plasmapheresis reduces the circulating immune complexes in the blood which cause the hemolysis, and may be beneficial in improving the outcome. Additionally, hemodialysis can be used for patients with compromised kidney function or kidney failure.
Paxillus involutus also contains agents which appear to damage chromosomes; it is unclear whether these have carcinogenic or mutagenic potential. Two compounds that have been identified are the phenols involutone and involutin; the latter is responsible for the brownish discolouration upon bruising.
Despite the poisonings, Paxillus involutus is still consumed in parts of Poland, Russia, and Ukraine, where people die from it every year.
See also
List of deadly fungi
References
External links
Paxillaceae
Deadly fungi
Fungi of Asia
Fungi of Europe
Fungi of North America
Fungi of South America
Fungi described in 1786
Taxa named by August Batsch
Fungus species | Paxillus involutus | Biology | 3,936 |
56,206,469 | https://en.wikipedia.org/wiki/NGC%207419 | NGC 7419 is an open cluster in the constellation Cepheus. It is heavily reddened and notable for containing five red supergiants, the highest number known in any cluster until the end of the 20th century, but probably no blue supergiants.
Members
The brightest of the five red supergiants is the exceptionally cool MY Cephei. It has a spectral type of M7.5 which is one of the latest spectral types of any supergiant, although analysis is made difficult by the lack of comparable standard stars. It is estimated to have an effective temperature around and a bolometric luminosity more than . MY Cephei is a semiregular variable star with a brightness range of magnitude 14.4 - 15.3.
The brightest hot stars in the cluster have a spectral type of BC2, indicating B2 stars with enhanced levels of carbon. One has a bright giant luminosity class of II, while the other has a luminosity class of Ib-II, indicating it is either a bright giant or supergiant. The hotter stars of the cluster are visually faint due to around six magnitudes of interstellar extinction.
The lack of blue supergiants, particularly in a cluster of just the right size and age to include five red supergiants, is unusual. Such low ratios of blue:red supergiants occur in low metallicity clusters, but NGC 7419 is young and has near-solar metallicity. Rapidly rotating stars may account for this evolutionary trend, encouraging high mass loss and rapid evolution of massive stars into red supergiants. This conclusion is also consistent with the high proportion of Be stars in the cluster.
The age of the cluster is calculated to be million years. Clusters of this age are expected to have a main sequence turnoff at spectral type B1, and this is seen in NGC 7419. of B-type stars alone are observed, implying a total cluster mass of .
Non-members
Visible in the same field and as prominent as the red supergiants in infrared images is the carbon star MZ Cephei, which is much closer to us than NGC 7419. It is a slow irregular variable star with a range of 14.7 - 15.4.
The visually brightest star in the core region of the cluster is a yellow giant, placed at around 500 parsecs by Gaia astrometry. The even brighter nearby star HD 216721 is also a foreground object. Further out still from the centre of the cluster is the 7th magnitude eclipsing binary V453 Cephei, around 250 parsecs distant from us.
See also
Stephenson 2
RSGC1
References
External links
Cepheus (constellation)
7419
Open clusters | NGC 7419 | Astronomy | 554 |
833,720 | https://en.wikipedia.org/wiki/Fiber%20simulation | Fiber simulation is a branch of mechanics that deals with modeling the dynamics and rheology of fibers, i.e. particles of large aspect ratio length to diameter. Fiber simulations are used to gain a better understanding of production processes including fibers (textile and paper industry), biological systems or computer graphics.
Modeling fibers
Many of the models used to simulate fibers were developed by researchers in the field of rheology. Rheologically speaking fiber suspensions are non-Newtonian fluids, and can display normal stress differences.
Simulation techniques
Early fiber simulations employed particles which were rigid rods or prolate spheroids, whose equations of motion have analytical solutions. More recent models are able to represent flexible fibers. The models rely heavily on continuum mechanics concepts and the numerical methods employed have some similarities to those employed in molecular dynamics, or in dynamics of multi body systems.
The use of computers facilitates greatly the solution of fiber simulation problems. The complexity of the simulations arise from the system having a large number of degrees of freedom, and from the numerous possible interparticle interactions having place, such as friction, hydrodynamic interactions, and other kinds of interparticle forces such as colloidal forces that exert attractive or repulsive forces.
References
Materials science | Fiber simulation | Physics,Materials_science,Engineering | 254 |
41,359,740 | https://en.wikipedia.org/wiki/Anochetus%20intermedius | Anochetus intermedius is an extinct species of ant in the subfamily Ponerinae known from two possibly Miocene fossils found on Hispaniola. A. intermedius is one of eight species in the ant genus Anochetus to have been described from fossils found in Dominican amber and is one of a number of Anochetus species found in the Greater Antilles.
History and classification
Anochetus intermedius is known from a solitary fossil insect which, along with two flies, three other ants, and two springtails, is an inclusion in a transparent yellow chunk of Dominican amber. The amber was produced by the extinct Hymenaea protera, which formerly grew on Hispaniola, across northern South America and up to southern Mexico. The specimen was collected from an undetermined amber mine in fossil bearing rocks of the Cordillera Septentrional mountains of northern Dominican Republic. The amber dates from at least the Burdigalian stage of the Miocene, based on studying the associated fossil foraminifera and may be as old as the Middle Eocene, based on the associated fossil coccoliths. This age range is due to the host rock being secondary deposits for the amber, and the Miocene the age range is only the youngest that it might be.
At the time of description, the holotype specimen was preserved in the Natural History Museum, London amber collections in London, England. The holotype fossil was first studied by entomologist Maria L. De Andrade of the University of Basle with her 1991 type description of the new species being published in the journal Stuttgarter Beiträge zur Naturkunde. Serie B (Geologie und Paläontologie). The specific epithet is derived from the Latin intermedius meaning "intermediate".
The species is one of eight Anochetus which have been described from Dominican amber. Two species were described prior to A. intermedius, A. corayi in 1980 and A. brevidentatus in 1991. The remaining five species; A. ambiguus, A. conisquamis, A. dubius, A. exstinctus, and A. lucidus were all described by De Andrade in the same 1994 paper as A. intermedius. A number of modern species live in the Greater Antilles, with at least three modern species found on Hispaniola.
Description
The Anochetus intermedius type specimen is fairly well preserved, though some body structures were lost prior to entombment and the specimen shows distortions along its full length from the resin flowing after entombment. The specimen has an estimated body length of , with a long head and long mandibles. The overall coloration of the body is a chestnut-yellow, with the coxae, femora, trochanters and mandible blades a yellowish tone, while the head, mandible tips, antennae, tibiae and tarsi are all brownish. The mandibles are one quarter times longer than the width of the head and just over the length, slightly flaring in width from the base to tips and have seven teeth on the left mandible, eight teeth on the right, all of which decrease in size from the tips to the bases. The apical three teeth on each mandible blade are elongated and slender for grasping prey. Both the mesonotum and pronotum have a slight "u" shaped profile, with the undersides of each curved upwards. The propodium sports short spines, long, on the rear edge, while the petiole has longer spines, , centrally placed.
References
†Anochetus intermedius
Fossil ant taxa
Burdigalian life
Miocene insects of North America
Prehistoric insects of the Caribbean
Fauna of Hispaniola
Insects of the Dominican Republic
Dominican amber
Fossil taxa described in 1994
Species known from a single specimen | Anochetus intermedius | Biology | 792 |
407,249 | https://en.wikipedia.org/wiki/Divisor%20function | In mathematics, and specifically in number theory, a divisor function is an arithmetic function related to the divisors of an integer. When referred to as the divisor function, it counts the number of divisors of an integer (including 1 and the number itself). It appears in a number of remarkable identities, including relationships on the Riemann zeta function and the Eisenstein series of modular forms. Divisor functions were studied by Ramanujan, who gave a number of important congruences and identities; these are treated separately in the article Ramanujan's sum.
A related function is the divisor summatory function, which, as the name implies, is a sum over the divisor function.
Definition
The sum of positive divisors function σz(n), for a real or complex number z, is defined as the sum of the zth powers of the positive divisors of n. It can be expressed in sigma notation as
where is shorthand for "d divides n".
The notations d(n), ν(n) and τ(n) (for the German Teiler = divisors) are also used to denote σ0(n), or the number-of-divisors function (). When z is 1, the function is called the sigma function or sum-of-divisors function, and the subscript is often omitted, so σ(n) is the same as σ1(n) ().
The aliquot sum s(n) of n is the sum of the proper divisors (that is, the divisors excluding n itself, ), and equals σ1(n) − n; the aliquot sequence of n is formed by repeatedly applying the aliquot sum function.
Example
For example, σ0(12) is the number of the divisors of 12:
while σ1(12) is the sum of all the divisors:
and the aliquot sum s(12) of proper divisors is:
σ−1(n) is sometimes called the abundancy index of n, and we have:
Table of values
The cases x = 2 to 5 are listed in through , x = 6 to 24 are listed in through .
Properties
Formulas at prime powers
For a prime number p,
because by definition, the factors of a prime number are 1 and itself. Also, where pn# denotes the primorial,
since n prime factors allow a sequence of binary selection ( or 1) from n terms for each proper divisor formed. However, these are not in general the smallest numbers whose number of divisors is a power of two; instead, the smallest such number may be obtained by multiplying together the first n Fermi–Dirac primes, prime powers whose exponent is a power of two.
Clearly, for all , and for all , .
The divisor function is multiplicative (since each divisor c of the product mn with distinctively correspond to a divisor a of m and a divisor b of n), but not completely multiplicative:
The consequence of this is that, if we write
where r = ω(n) is the number of distinct prime factors of n, pi is the ith prime factor, and ai is the maximum power of pi by which n is divisible, then we have:
which, when x ≠ 0, is equivalent to the useful formula:
When x = 0, is:
This result can be directly deduced from the fact that all divisors of are uniquely determined by the distinct tuples of integers with (i.e. independent choices for each ).
For example, if n is 24, there are two prime factors (p1 is 2; p2 is 3); noting that 24 is the product of 23×31, a1 is 3 and a2 is 1. Thus we can calculate as so:
The eight divisors counted by this formula are 1, 2, 4, 8, 3, 6, 12, and 24.
Other properties and identities
Euler proved the remarkable recurrence:
where if it occurs and for , and are consecutive pairs of generalized pentagonal numbers (, starting at offset 1). Indeed, Euler proved this by logarithmic differentiation of the identity in his pentagonal number theorem.
For a non-square integer, n, every divisor, d, of n is paired with divisor n/d of n and is even; for a square integer, one divisor (namely ) is not paired with a distinct divisor and is odd. Similarly, the number is odd if and only if n is a square or twice a square.
We also note s(n) = σ(n) − n. Here s(n) denotes the sum of the proper divisors of n, that is, the divisors of n excluding n itself. This function is used to recognize perfect numbers, which are the n such that s(n) = n. If s(n) > n, then n is an abundant number, and if s(n) < n, then n is a deficient number.
If is a power of 2, , then and , which makes n almost-perfect.
As an example, for two primes , let
.
Then
and
where is Euler's totient function.
Then, the roots of
express p and q in terms of σ(n) and φ(n) only, requiring no knowledge of n or , as
Also, knowing and either or , or, alternatively, and either or allows an easy recovery of p and q.
In 1984, Roger Heath-Brown proved that the equality
is true for infinitely many values of , see .
Dirichlet convolutions
By definition:By Möbius inversion:
Series relations
Two Dirichlet series involving the divisor function are:
where is the Riemann zeta function. The series for d(n) = σ0(n) gives:
and a Ramanujan identity
which is a special case of the Rankin–Selberg convolution.
A Lambert series involving the divisor function is:
for arbitrary complex |q| ≤ 1 and a. This summation also appears as the Fourier series of the Eisenstein series and the invariants of the Weierstrass elliptic functions.
For , there is an explicit series representation with Ramanujan sums as :
The computation of the first terms of shows its oscillations around the "average value" :
Growth rate
In little-o notation, the divisor function satisfies the inequality:
More precisely, Severin Wigert showed that:
On the other hand, since there are infinitely many prime numbers,
In Big-O notation, Peter Gustav Lejeune Dirichlet showed that the average order of the divisor function satisfies the following inequality:
where is Euler's gamma constant. Improving the bound in this formula is known as Dirichlet's divisor problem.
The behaviour of the sigma function is irregular. The asymptotic growth rate of the sigma function can be expressed by:
where lim sup is the limit superior. This result is Grönwall's theorem, published in 1913 . His proof uses Mertens' third theorem, which says that:
where p denotes a prime.
In 1915, Ramanujan proved that under the assumption of the Riemann hypothesis, Robin's inequality
(where γ is the Euler–Mascheroni constant)
holds for all sufficiently large n . The largest known value that violates the inequality is n=5040. In 1984, Guy Robin proved that the inequality is true for all n > 5040 if and only if the Riemann hypothesis is true . This is Robin's theorem and the inequality became known after him. Robin furthermore showed that if the Riemann hypothesis is false then there are an infinite number of values of n that violate the inequality, and it is known that the smallest such n > 5040 must be superabundant . It has been shown that the inequality holds for large odd and square-free integers, and that the Riemann hypothesis is equivalent to the inequality just for n divisible by the fifth power of a prime .
Robin also proved, unconditionally, that the inequality:
holds for all n ≥ 3.
A related bound was given by Jeffrey Lagarias in 2002, who proved that the Riemann hypothesis is equivalent to the statement that:
for every natural number n > 1, where is the nth harmonic number, .
See also
Divisor sum convolutions, lists a few identities involving the divisor functions
Euler's totient function, Euler's phi function
Refactorable number
Table of divisors
Unitary divisor
Notes
References
.
Bach, Eric; Shallit, Jeffrey, Algorithmic Number Theory, volume 1, 1996, MIT Press. , see page 234 in section 8.8.
External links
Elementary Evaluation of Certain Convolution Sums Involving Divisor Functions PDF of a paper by Huard, Ou, Spearman, and Williams. Contains elementary (i.e. not relying on the theory of modular forms) proofs of divisor sum convolutions, formulas for the number of ways of representing a number as a sum of triangular numbers, and related results.
Analytic number theory
Number theory
Zeta and L-functions | Divisor function | Mathematics | 1,956 |
10,151,154 | https://en.wikipedia.org/wiki/Lagrange%20point%20colonization | Lagrange point colonization is a proposed form of space colonization of the five equilibrium points in the orbit of a planet or its primary moon, called Lagrange points.
The Lagrange points and are stable if the mass of the larger body is at least 25 times the mass of the secondary body. Thus, the points L4 and L5 in the Earth–Moon system have been proposed as possible sites for space colonies. The L5 Society was founded to promote settlement by building space stations at these points.
Gerard K. O'Neill suggested in 1974 that the Earth–Moon L5 point, in particular, could fit several thousands of floating colonies, and would allow easy travel to and from the colonies due to the shallow effective potential at this point. A contemporary NASA team estimated that a 500,000-tonne colony would cost US$5.1 billion (equivalent to US$ billion in ) to build.
O'Neill proposed manufacturing large cylinders or spheres as colony habitats, while others proposed an enclosed torus shape or a huge ring without a "roof". Another approach is to move an asteroid to a Lagrange point with a colony in its hollow interior.
See also
Interplanetary Transport Network
Lissajous orbit
References
External links
Dictionary Definition
European Space Agency
Free Mars
Orbital Vector
NASA - The Moon and the Magnetotail
Space colonization | Lagrange point colonization | Astronomy | 273 |
78,796,818 | https://en.wikipedia.org/wiki/Allisartan%20isoproxil | Allisartan isoproxil is an antihypertensive pharmaceutical drug. It belongs to the angiotensin II receptor blocker class of drugs. It is an esterified prodrug, and its metabolism results in the formation of a single metabolite, losartan carboxylic acid (EXP3174), an oxidized form of losartan.
In China, allisartan isoproxil was approved by the Chinese Food and Drug Administration for the treatment of hypertension in 2012, and introduced to the market in 2013.
References
Angiotensin II receptor antagonists
Biphenyls
Butyl compounds
Chloroarenes
Imidazoles
Tetrazoles
Carbonate esters
Esters
Isopropyl compounds
Prodrugs | Allisartan isoproxil | Chemistry | 166 |
40,559,984 | https://en.wikipedia.org/wiki/Standard%20Test%20and%20Programming%20Language | JAM / STAPL ("Standard Test and Programming Language") is an Altera-developed standard for JTAG in-circuit programming of programmable logic devices (PLDs). It is defined by JEDEC standard JESD-71.
STAPL defines a standard .jam file format which supports in-system programmability or configuration of programmable devices. A JTAG device programmer implements a JAM player which reads the file as a set of instructions directing it to program a PLD.
The standard is supported by multiple PLD and device programmer manufacturers.
References
JEDEC standards
Electronics manufacturing
Embedded systems | Standard Test and Programming Language | Technology,Engineering | 124 |
36,665,815 | https://en.wikipedia.org/wiki/Timeline%20of%20Mars%20Science%20Laboratory | The Mars Science Laboratory and its rover, Curiosity, were launched from Earth on 26 November 2011. As of , , Curiosity has been on the planet Mars for sols ( total days; ) since landing on 6 August 2012. (See Current status.)
Prelaunch (2004–2011)
In April 2004, the United States National Aeronautics and Space Administration (NASA) called for scientific experiments and instruments proposals for the Mars Science Laboratory and rover mission. Launch was proposed for September 2009. By 14 December 2004, eight proposals were selected, including instruments from Russia and Spain.
Testing of components also began in late 2004, including Aerojet's monopropellant engine with the ability to throttle from 15 to 100 percent thrust with a fixed propellant inlet pressure. By November 2008 most hardware and software development was complete, and testing continued. At this point, cost overruns were approximately $400 million. In December 2008, lift-off was delayed to November 2011 due to insufficient time for testing and integration.
Between 23–29 March 2009, the general public ranked nine finalist rover names (Adventure, Amelia, Journey, Perception, Pursuit, Sunrise, Vision, Wonder, and Curiosity) through a public poll on the NASA website. On 27 May 2009, the winning name was announced to be Curiosity. The name had been submitted in an essay contest by Clara Ma, a then sixth-grader from Kansas.
Landing site selection
At the first MSL Landing Site workshop, 33 potential landing sites were identified. By the second workshop in late 2007, the list had grown to include almost 50 sites, and by the end of the workshop, the list was reduced to six; in November 2008, project leaders at a third workshop reduced the list to these four landing sites:
A fourth landing site workshop was held in late September 2010, and the fifth and final workshop 16–18 May 2011. On 22 July 2011, it was announced that Gale Crater had been selected as the landing site of the Mars Science Laboratory mission.
Launch (2011)
MSL was launched from Cape Canaveral Air Force Station Space Launch Complex 41 on 26 November 2011, at 10:02 EST (15:02 UTC) aboard an Atlas V 541 provided by United Launch Alliance. The first and second rocket stages, along with the rocket motors, were stacked on 9 October 2011, near the launch pad. The fairing containing the spacecraft was transported to the launch pad on 3 November 2011.
On 13 December 2011, the rover began monitoring space radiation to aid in planning for future crewed missions to Mars.
The interplanetary journey to Mars took more than eight months, time during which, the spacecraft performed four trajectory corrections: on 11 January, 26 March, 26 June and on 28 July. Mission design had allowed for a maximum of 6 trajectory correction opportunities.
Landing (2012)
Curiosity landed in the Gale Crater at 05:17 UTC on 6 August 2012. Upon reaching Mars, an automated precision landing sequence took over the entire landing events. A cable cutter separated the cruise stage from the aeroshell and then the cruise stage was diverted into a trajectory for burn-up in the atmosphere. Landing was confirmed simultaneously by 3 monitoring Mars orbiters. Curiosity landed on target and only from its center. The coordinates of the landing site (named "Bradbury Landing") are: .
Some low resolution Hazcam images were beamed to Earth by relay orbiters confirming the rover's wheels were deployed correctly and on the ground. Three hours later, the rover begins to beam detailed data on its systems' status as well as on its entry, descent and landing experience. Aerial 3-D images of the landing site are available and include: the Curiosity rover and related Parachute (HiRISE, 10 October 2012).
On 8 August 2012, Mission Control began upgrading the rover's dual computers by deleting the entry-descent-landing software, then uploading and installing the surface operation software; the switchover was completed by 15 August.
Prime mission (2012 - September 2014)
On 15 August 2012, the rover began several days of instrument checks and mobility tests. The first laser testing of the ChemCam by Curiosity on Mars was performed on a rock, N165 ("Coronation" rock), near Bradbury Landing on 19 August 2012.
The science and operations teams have identified at least six possible routes to the base of Mount Sharp, and estimate about a year studying the rocks and soil of the crater floor while Curiosity slowly makes its way to the base of the mountain. The ChemCam team expects to take approximately one dozen compositional measurements of rocks per day.
Having completed its mobility tests, the rover's first drive began on 29 August 2012, to a place called Glenelg about to the east. Glenelg is a location where three types of terrain intersect, and is the mission's first major driving destination. The drive across may take up to two months, after which Curiosity will stay at Glenelg for a month.
On the way, Curiosity studied a pyramidal rock dubbed "Jake Matijevic" after a mathematician-turned-rover-engineer who played a critical role in the design of the six-wheeled rover, but died just days after Curiosity landed in August.
The Jake rock measures about tall and wide. It is an igneous rock and may be a mugearite, a sodium rich oligoclase-bearing basaltic trachyandesite. Afterwards, on 30 September 2012, a finely-grained rock, named "Bathurst Inlet", was examined by Curiosity Mars Hand Lens Imager (MAHLI) and Alpha particle X-ray spectrometer (APXS). The rock was named after Bathurst Inlet, a deep inlet located along the northern coast of the Canadian mainland. Also, a sand patch, named "Rocknest", is a test target for the first use of the scoop on the arm of the Curiosity rover.
Evidence for ancient water
On 27 September 2012, NASA scientists announced that the Curiosity rover found evidence for an ancient streambed suggesting a "vigorous flow" of water on Mars.
On 7 October 2012, a mysterious "bright object" (image), discovered in the sand at Rocknest, drew scientific interest. Several close-up pictures (close-up 1) (close-up 2) were taken of the object and preliminary interpretations by scientists suggest the object to be "debris from the spacecraft". Nonetheless, further images in the nearby sand have detected other "bright particles" (image) (close-up 1). These newly discovered objects are presently thought to be "native Martian material".
On 17 October 2012, at Rocknest, the first X-ray diffraction analysis of Martian soil was performed. The results revealed the presence of several minerals, including feldspar, pyroxenes and olivine, and suggested that the Martian soil in the sample was similar to the weathered basaltic soils of Hawaiian volcanoes. The sample used is composed of dust distributed from global dust storms and local fine sand. So far, the materials Curiosity has analyzed are consistent with the initial ideas of deposits in Gale Crater recording a transition through time from a wet to dry environment.
On 22 November 2012, the Curiosity rover analyzed a rock named "Rocknest 3" with the APXS and then resumed traveling toward "Point Lake" overlook on its way to Glenelg Intrigue.
On 3 December 2012, NASA reported that Curiosity performed its first extensive soil analysis, revealing the presence of water molecules, sulfur and chlorine in the Martian soil. The presence of perchlorates in the sample seems highly likely. The presence of sulfate and sulfide is also likely because sulfur dioxide and hydrogen sulfide were detected. Small amounts of chloromethane, dichloromethane and trichloromethane were detected. The source of the carbon in these molecules is unclear. Possible sources include contamination of the instrument, organics in the sample and inorganic carbonates.
Evidence for ancient habitability
In February 2013, the rover used its drill for the first time.
In March 2013, NASA reported Curiosity found evidence that geochemical conditions in Gale Crater were once suitable for microbial life after analyzing the first drilled sample of Martian rock, "John Klein" rock at Yellowknife Bay in Gale Crater. The rover detected water, carbon dioxide, oxygen, sulfur dioxide and hydrogen sulfide. Chloromethane and dichloromethane were also detected. Related tests found results consistent with the presence of smectite clay minerals. In addition, sandstone beds associated with the Gillespie Lake Member of Yellowknife Bay seem similar to microbially induced sedimentary structures (MISS) found on Earth, according to one study.
Evidence for atmospheric loss
On 8 April 2013, NASA reported that much of the atmosphere of Mars has been lost based on argon isotope ratios studies.
On 19 July 2013, NASA scientists published the results of a new analysis of the atmosphere of Mars, reporting a lack of methane around the landing site of the Curiosity rover. In addition, the scientists found evidence that Mars "has lost a good deal of its atmosphere over time", based on the abundance of isotopic compositions of gases, particularly those related to argon and carbon.
Other 2013 events
On 28 February 2013, NASA was forced to switch to the backup computer due to an issue with the then active computer's flash memory which resulted in the computer continuously rebooting in a loop. The backup computer was turned on in safe mode and was converted to operational status on 19 March 2013.
On 18 March 2013, NASA reported evidence of mineral hydration, likely hydrated calcium sulfate, in several rock samples including the broken fragments of "Tintina" rock and "Sutton Inlier" rock as well as in veins and nodules in other rocks like "Knorr" rock and "Wernicke" rock. Analysis using the rover's DAN instrument provided evidence of subsurface water, amounting to as much as 4% water content, down to a depth of , in the rover's traverse from the Bradbury Landing site to the Yellowknife Bay area in the Glenelg terrain.
Between 4 April – 1 May 2013, Curiosity operated autonomously due to a Martian solar conjunction with Earth. While Curiosity transmitted a beep to Earth each day and the Odyssey spacecraft continued to relay information from the rover, no commands were sent from mission control since there was a possibility of data corruption due to interference from the Sun. Curiosity continued to perform stationary science at Yellowknife Bay for the duration of the conjunction.
On 5 June 2013, NASA announced that Curiosity will soon begin a journey from the Glenelg area to the base of Mount Sharp. The trip is expected to take nine months to a year with stops along the way to study the local terrain.
On 16 July 2013, the Curiosity rover reached a milestone in its journey across Mars, having traveled , since its landing in 2012; on 1 August 2013, the rover traveled over one mile: .
On 6 August 2013, NASA celebrated Curiosity first year on Mars (6 August 2012 to 5 August 2013) by programming the rover to perform the "Happy Birthday" song to itself. NASA also released several videos (video-1, video-2) summarizing the rover's accomplishments over the year. Primarily, the mission found evidence of "ancient environments suitable for life" on Mars. The rover drove over one-mile across the Martian terrain, transmitted more than 190 gigabits of data to Earth, including 70,000 images (36,700 full images and 35,000 thumbnails), and the rover's laser fired more than 75,000 times at 2,000 targets.
On 27 August 2013, Curiosity used autonomous navigation (or "autonav"- the ability of the rover to decide for itself how to drive safely) over unknown Martian ground for the first time.
On 19 September 2013, NASA scientists, on the basis of further measurements by Curiosity, reported no detection of atmospheric methane with a measured value of ppbv corresponding to an upper limit of only 1.3 ppbv (95% confidence limit) and, as a result, conclude that the probability of current methanogenic microbial activity on Mars is reduced.
On 26 September 2013, NASA scientists reported the Mars Curiosity rover detected "abundant, easily accessible" water (1.5 to 3 weight percent) in soil samples at the Rocknest region of Aeolis Palus in Gale Crater. In addition, NASA reported that the Curiosity rover found two principal soil types: a fine-grained mafic type and a locally derived, coarse-grained felsic type. The mafic type, similar to other Martian soils and Martian dust, was associated with hydration of the amorphous phases of the soil. Also, perchlorates, the presence of which may make detection of life-related organic molecules difficult, were found at the Curiosity rover landing site (and earlier at the more polar site of the Phoenix lander) suggesting a "global distribution of these salts". NASA also reported that Jake M rock, a rock encountered by Curiosity on the way to Glenelg, was a mugearite and very similar to terrestrial mugearite rocks.
On 17 October 2013, NASA reported, based on analysis of argon in the Martian atmosphere, that certain meteorites found on Earth thought to be from Mars are confirmed to be from Mars.
On 13 November 2013, NASA announced the names of two features on Mars important to two active Mars exploration rovers in honor of planetary scientist Bruce C. Murray (1931-2013): "Murray Buttes", an entryway the Curiosity rover will traverse on its way to Mount Sharp and "Murray Ridge", an uplifted crater that the Opportunity rover is exploring.
On 25 November 2013, NASA reported that Curiosity has resumed full science operations, with no apparent loss of capability, after completing the diagnosis of an electrical problem first observed on 17 November. Apparently, an internal short in the rover's power source, the Multi-Mission Radioisotope Thermoelectric Generator, caused an unusual and intermittent decrease in a voltage indicator on the rover.
On 27 November 2013, an overview (titled, "The World of Mars") of current and proposed Mars exploration by John Grotzinger, chief scientist of the Curiosity rover mission, was published in the New York Times.
On 9 December 2013, NASA reported that the planet Mars had a large freshwater lake (which could have been a hospitable environment for microbial life) based on evidence from the Curiosity rover studying Aeolis Palus near Mount Sharp in Gale Crater.
On 9 December 2013, NASA researchers described, in a series of six articles in the journal Science, many new discoveries from the Curiosity rover. Possible organics were found that could not be explained by contamination. Although the organic carbon was probably from Mars, it can all be explained by dust and meteorites that have landed on the planet. Because much of the carbon was released at a relatively low temperature in Curiosity Sample Analysis at Mars (SAM) instrument package, it probably did not come from carbonates in the sample. The carbon could be from organisms, but this has not been proven. This organic-bearing material was obtained by drilling 5 centimeters deep in a site called Yellowknife Bay into a rock called "Sheepbed mudstone". The samples were named John Klein and Cumberland. Microbes could be living on Mars by obtaining energy from chemical imbalances between minerals in a process called chemolithotrophy which means "eating rock." However, in this process only a very tiny amount of carbon is involved — much less than was found at Yellowknife Bay.
Using SAM's mass spectrometer, scientists measured isotopes of helium, neon, and argon that cosmic rays produce as they go through rock. The fewer of these isotopes they find, the more recently the rock has been exposed near the surface. The 4-billion-year-old lakebed rock drilled by Curiosity was uncovered between 30 million and 110 million years ago by winds which sandblasted away 2 meters of overlying rock. Next, they hope to find a site tens of millions of years younger by drilling close to an overhanging outcrop.
The absorbed dose and dose equivalent from galactic cosmic rays and solar energetic particles on the Martian surface for ~300 days of observations during the current solar maximum was measured. These measurements are necessary for human missions to the surface of Mars, to provide microbial survival times of any possible extant or past life, and to determine how long potential organic biosignatures can be preserved. This study estimates that a 1-meter depth drill is necessary to access possible viable radioresistant microbe cells. The actual absorbed dose measured by the Radiation Assessment Detector (RAD) is 76 mGy/yr at the surface. Based on these measurements, for a round trip Mars surface mission with 180 days (each way) cruise, and 500 days on the Martian surface for this current solar cycle, an astronaut would be exposed to a total mission dose equivalent of ~1.01 sievert. Exposure to 1 sievert is associated with a 5 percent increase in risk for developing fatal cancer. NASA's current lifetime limit for increased risk for its astronauts operating in low-Earth orbit is 3 percent. Maximum shielding from galactic cosmic rays can be obtained with about 3 meters of Martian soil.
The samples examined were probably once mud that for millions to tens of millions of years could have hosted living organisms. This wet environment had neutral pH, low salinity, and variable redox states of both iron and sulfur species. These types of iron and sulfur could have been used by living organisms. C, H, O, S, N, and P were measured directly as key biogenic elements, and by inference, P is assumed to have been there as well. The two samples, John Klein and Cumberland, contain basaltic minerals, Ca-sulfates, Fe oxide/hydroxides, Fe-sulfides, amorphous material, and trioctahedral smectites (a type of clay). Basaltic minerals in the mudstone are similar to those in nearby aeolian deposits. However, the mudstone has far less Fe-forsterite plus magnetite, so Fe-forsterite (type of olivine) was probably altered to form smectite (a type of clay) and magnetite. A Late Noachian/Early Hesperian or younger age indicates that clay mineral formation on Mars extended beyond Noachian time; therefore, in this location neutral pH lasted longer than previously thought.
On 20 December 2013, NASA reported that Curiosity has successfully upgraded, for the third time since landing, its software programs and is now operating with version 11. The new software is expected to provide the rover with better robotic arm and autonomous driving abilities. Due to wheel wear, a concern to drive more carefully over the rough terrain the rover is currently traveling on to Mount Sharp, was also reported.
Search for ancient life
On 24 January 2014, NASA reported that current studies by the Curiosity and Opportunity rovers will now be searching for evidence of ancient life, including a biosphere based on autotrophic, chemotrophic and/or chemolithoautotrophic microorganisms, as well as ancient water, including fluvio-lacustrine environments (plains related to ancient rivers or lakes) that may have been habitable. The search for evidence of habitability, taphonomy (related to fossils), and organic carbon on the planet Mars is now a primary NASA objective.
Arrival at Mount Sharp
On 11 September 2014 (Sol 746), Curiosity reached the slopes of Aeolis Mons (or Mount Sharp), the rover mission's long-term prime destination and where the rover is expected to learn more about the history of Mars. Curiosity had traveled an estimated linear distance of to the mountain slopes since leaving its "start" point in Yellowknife Bay on 4 July 2013.
Detection of organics
On 16 December 2014, NASA reported the Curiosity rover detected a "tenfold spike", likely localized, in the amount of methane in the Martian atmosphere. Sample measurements taken "a dozen times over 20 months" showed increases in late 2013 and early 2014, averaging "7 parts of methane per billion in the atmosphere." Before and after that, readings averaged around one-tenth that level. In addition, high levels of organic chemicals, particularly chlorobenzene, were detected in powder drilled from one of the rocks, named "Cumberland", analyzed by the Curiosity rover.
Other 2014 events
On 6 February 2014, the Curiosity rover, in order to reduce wear on its wheels by avoiding rougher terrain, successfully crossed (image) the "Dingo Gap" sand dune and is now expected to travel a smoother route to Mount Sharp.
On 19 May 2014, scientists announced that numerous microbes, like Tersicoccus phoenicis, may be resistant to methods usually used in spacecraft assembly clean rooms. It's not currently known if such resistant microbes could have withstood space travel and are present on the Curiosity rover now on Mars.
On 25 May 2014, Curiosity discovered an iron meteorite, and named it "Lebanon" (image).
On 3 June 2014, Curiosity observed the planet Mercury transiting the Sun, marking the first time a planetary transit has been observed from a celestial body besides Earth.
On 24 June 2014, Curiosity completed a Martian year—687 Earth days—after finding that Mars once had environmental conditions favorable for microbial life.
On 27 June 2014, Curiosity crossed the boundary line of its "3-sigma safe-to-land ellipse" and is now in territory that may get even more interesting, especially in terms of Martian geology and landscape (view from space).
On 12 July 2014, Curiosity imaged the first laser spark on Mars (related image; video (01:07).)
On 6 August 2014, Curiosity celebrated its second anniversary since landing on Mars in 2012.
On 11 September 2014, a panel of NASA scientists announced (video (01:25)) the arrival of Curiosity at Mount Sharp and discussed future rover plans.
First extended mission (October 2014 - September 2016)
On 19 October 2014, the Curiosity rover viewed the flyby of Comet C/2013 A1.
On 8 December 2014, a panel of NASA scientists discussed (archive 62:03) the latest observations of Curiosity, including findings about how water may have helped shape the landscape of Mars and had a climate long ago that could have produced long-lasting lakes at many Martian locations.
On 16 December 2014, NASA reported detecting an unusual increase, then decrease, in the amounts of methane in the atmosphere of the planet Mars; in addition, organic chemicals were detected in powder drilled from a rock by the Curiosity rover. Also, based on deuterium to hydrogen ratio studies, much of the water at Gale Crater on Mars was found to have been lost during ancient times, before the lakebed in the crater was formed; afterwards, large amounts of water continued to be lost.
On 21 January 2015, NASA announced a collaborative effort with Microsoft that developed a software project called OnSight which allows scientists to perform virtual work on Mars based on data from the Curiosity rover.
On 6 March 2015, NASA reported performing tests on the rover to help uncover the reason for intermittent problems with the robotic arm used for rock drilling and analysis. Results of preliminary tests suggest the intermittent short-circuit problem may be related to the percussion mechanism of the drill. Further tests are planned to verify and adjust to the problem.
On 24 March 2015, NASA reported the first detection of nitrogen released after heating surface sediments on the planet Mars. The nitrogen, in the form of nitric oxide, was detected by the SAM instrument on the Curiosity rover and can be used by living organisms. The discovery supports the notion that ancient Mars may have been habitable for life.
On 27 March 2015, NASA reported that the landing site was fading from view in the two-and-a-half years since landing in 2012.
On 4 April 2015, NASA reported studies, based on measurements by the Sample Analysis at Mars (SAM) instrument on the Curiosity rover, of the Martian atmosphere using xenon and argon isotopes. Results provided support for a "vigorous" loss of atmosphere early in the history of Mars and were consistent with an atmospheric signature found in bits of atmosphere captured in some Martian meteorites found on Earth.On 19 August 2015, NASA scientists reported that the Dynamic Albedo of Neutrons (DAN) instrument on the Curiosity rover detected an unusual hydrogen-rich area, at "Marias Pass," on Mars. The hydrogen found seemed related to water or hydroxyl ions in rocks within three feet beneath the rover, according to the scientists.
On 5 October 2015, possible recurrent slope lineae, wet brine flows, were reported on Mount Sharp near Curiosity. In addition, on 5 October 2015, NASA reported an estimated 20,000 to 40,000 heat-resistant bacterial spores were on Curiosity at launch, as much as 1,000 times more than that may not have been counted.
On 8 October 2015, NASA confirmed that lakes and streams existed in Gale crater 3.3 - 3.8 billion years ago delivering sediments to build up the lower layers of Mount Sharp.
On 17 December 2015, NASA reported that as Curiosity climbed higher up Mount Sharp, the composition of rocks were changing substantially. For example, rocks found higher up the mountain contained much higher levels of silica than the basaltic rocks found earlier. After further analysis, the silica-rich rocks on Mars were found to be tridymite, a mineral that is not commonly found on Earth. Opal-A, another form of silica, was also found on Mars.
Second extended mission (October 2016 - September 2019)
The second extended mission began on 1 October 2016. The rover explored a ridge known as the Murray Formation for most of the mission.
As of 3 October 2016, NASA summarized the findings of the mission, thus far, as follows: "The Curiosity mission has already achieved its main goal of determining whether the landing region ever offered environmental conditions that would have been favorable for microbial life, if Mars has ever hosted life. The mission found evidence of ancient rivers and lakes, with a chemical energy source and all of the chemical ingredients necessary for life as we know it." Plans for the next two years, up to September 2018, include further explorations of the uphill slopes of Mount Sharp, including a ridge rich in the mineral hematite and a region of clay-rich bedrock.
On 13 December 2016, NASA reported further evidence supporting habitability on Mars as the Curiosity rover climbed higher, studying younger layers, on Mount Sharp. Also reported, the very soluble element boron was detected for the first time on Mars. Since landing on Mars in August 2012, Curiosity has driven and climbed in elevation.
On 17 January 2017, NASA released an image of a rock slab, named "Old Soaker", which may contain mud cracks. Also, somewhat later, it released an animation of sand moving in a nearby area.
On 6 February 2017, NASA reported that rock samples analyzed by the rover have not revealed any significant carbonate. This poses a puzzle to researchers: the same rocks that indicate a lake existed also indicate there was very little carbon dioxide in the air to help keep the lake unfrozen.
On 27 February 2017, NASA presented the following mission overview: "During the first year after Curiosity's 2012 landing in Gale Crater, the mission fulfilled its main goal by finding that the region once offered environmental conditions favorable for microbial life. The conditions in long-lived ancient freshwater Martian lake environments included all of the key chemical elements needed for life as we know it, plus a chemical source of energy that is used by many microbes on Earth. The extended mission is investigating how and when the habitable ancient conditions evolved into conditions drier and less favorable for life."
From 3 to 7 May 2017, Curiosity used ChemCam to study what turned out to be manganese oxide deposits on the Sutton Island and Blunts Point layers of the Murray Formation. According to a 2024 paper, the deposits suggest Earth-level amounts of oxygen were present in the very early Martian atmosphere, hinting at microbial life.
On 1 June 2017, NASA reported that the Curiosity rover provided evidence of an ancient lake in Gale crater on Mars that could have been favorable for microbial life; the ancient lake was stratified, with shallows rich in oxidants and depths poor in oxidants, particularly silica; the ancient lake provided many different types of microbe-friendly environments at the same time. NASA further reported that the Curiosity rover will continue to explore higher and younger layers of Mount Sharp in order to determine how the lake environment in ancient times on Mars became the drier environment in more modern times.
Between 22 July – 1 August 2017, few commands were sent from the Earth to Mars since Mars was in conjunction with the sun.
On 5 August 2017, NASA celebrated the fifth anniversary of the Curiosity rover mission landing, and related exploratory accomplishments, on the planet Mars. (Videos: Curiosity First Five Years (02:07); Curiosity POV: Five Years Driving (05:49); Curiosity Discoveries About Gale Crater (02:54))
On 5 September 2017, scientists reported that the Curiosity rover detected boron, an essential ingredient for life on Earth, on the planet Mars. Such a finding, along with previous discoveries that water may have been present on ancient Mars, further supports the possible early habitability of Gale Crater on Mars.
On 13 September 2017, NASA reported that the Curiosity rover climbed an iron-oxide-bearing ridge called Vera Rubin Ridge (or Hematite Ridge) and will now start studying the numerous bright veins embedded in the various layers of the ridge, in order to provide more details about the history and habitability of ancient Mars.
On 30 September 2017, NASA reported radiation levels on the surface of the planet Mars were temporarily doubled, and were associated with an aurora 25-times brighter than any observed earlier, due to a massive, and unexpected, solar storm in the middle of the month.
On 17 October 2017, NASA announced the testing of its systems on Curiosity in an attempt to better resume drilling. The drilling system had stopped working reliably in December 2016.
On 2 January 2018, Curiosity captured images of rock shapes that may require further study in order to help better determine whether the shapes are biological or geological.
On 22 March 2018, Curiosity had spent 2000 sols (2054 days) on Mars, and prepares to study a region of clay-bearing rocks.
In June 2018, a local dust storm occurred near the Opportunity rover which may affect Curiosity. The first signs of the storm, from Opportunity, were discovered on 1 June 2018, in photographs by the Mars Color Imager (MARCI) camera on the Mars Reconnaissance Orbiter (MRO). More weather reports from the MRO and the MARCI team indicated a prolonged storm. Although this was, at that time, still far away from the rover, it influenced the atmospheric permeability (opacity) at the location. Within days, the storm had spread. As of 12 June 2018, the storm spanned an area of - about the area of North America and Russia combined. Although such dust storms are not surprising, they rarely occur. They can arise within a short time and then persist for weeks to months. During the southern season of summer, the sunlight heats dust particles and brings them higher into the atmosphere. This creates wind, which in turn stirs up more dust. This results in a feedback loop that scientists are still trying to understand. NASA reported on 20 June 2018, that the dust storm had grown to completely cover the entire planet.
On 4 June 2018, NASA announced that Curiosity ability to drill has been sufficiently restored by engineers. The rover had experienced drill mechanical problems since December 2016.
On 7 June 2018, NASA announced a cyclical seasonal variation in atmospheric methane, as well as the presence of kerogen and other complex organic compounds. The organic compounds were from mudstone rocks aged approximately 3.5 billion years old, sampled from two distinct sites in a dry lake in the Pahrump Hills of the Gale crater. The rock samples, when pyrolyzed via the Curiositys Sample Analysis at Mars instrument, released an array of organic molecules; these include sulfur-containing thiophenes, aromatic compounds such as benzene and toluene, and aliphatic compounds such as propane and butene. The concentration of organic compounds are 100-fold higher than earlier measurements. The authors speculate that the presence of sulfur may have helped preserve them. The products resemble those obtained from the breakdown of kerogen, a precursor to oil and natural gas on Earth. NASA stated that these findings are not evidence that life existed on the planet, but that the organic compounds needed to sustain microscopic life were present, and that there may be deeper sources of organic compounds on the planet.
Since 15 September 2018, a glitch in Curiosity's active computer (Side-B) has prevented Curiosity from storing science and key engineering data. On 3 October 2018, the JPL began operating Curiosity on its backup computer (Side-A). Curiosity will store science and engineering data normally using its Side-A computer until the cause of the glitch in Side-B is determined and remedied.
On 4 November 2018, geologists presented evidence, based on studies in Gale Crater by the Curiosity rover, that there was plenty of water on early Mars.
On 26 November 2018, Curiosity viewed a shiny object (named, "Little Colonsay") on Mars. Although possibly a meteorite, further studies are planned to better understand its nature.
On 1 February 2019, NASA scientists reported that the Mars Curiosity rover determined, for the first time, the density of Mount Sharp in Gale crater, thereby establishing a clearer understanding of how the mountain was formed.
On 4 April 2019, NASA released images of solar eclipses by the two moons of the planet Mars, Phobos (animation1) and Deimos (animation2), as viewed by the Curiosity rover on the planet Mars in March 2019.
On 11 April 2019, NASA announced that the Curiosity rover on the planet Mars drilled into, and closely studied, a "clay-bearing unit" which, according to the rover Project Manager, is a "major milestone" in Curiosity journey up Mount Sharp.
During June 2019, while still studying the clay-bearing unit, Curiosity detected the highest levels of methane gas, 21 parts per billion, compared to the typical 1 part per billion the rover detects as normal background readings. The levels of methane dropped quickly over a few days, leading NASA to call this event one of several methane plumes that they have observed before but without any observable pattern. The rover lacked the necessary instrumentation to determine if the methane was biological or inorganic in nature.
Third extended mission (October 2019 - September 2022)
The third extended mission began on 1 October 2019 - the rover's 2544th sol on Mars.
In October 2019, evidence in the form of magnesium sulfate deposits left behind in ways that suggested evaporation, uncovered by the Curiosity rover on Mount Sharp, was reported of a wide ancient basin in Gale crater that once may have contained a salty lake.
In January 2020, a report was presented that compared Curiosity at the time of its landing on Mars in 2012, with the rover over seven years later in 2020.
In February 2020, scientists reported the detection of thiophene organic molecules by the Curiosity rover on the planet Mars. It is not currently known if the detected thiophenes — usually associated on Earth with kerogen, coal and crude oil — are the result of biological or non-biological processes.
In April 2020, scientists began operating the rover remotely from their homes due to the COVID-19 pandemic.
On 29 August 2020, NASA released several videos taken by the Curiosity rover, including those involving dust devils, as well as very high resolution images of the related local martian terrain.
In June 2021, scientists determined that the methane concentration around Curiosity varied according to the time of sol, with methane present only at night. This explains the difference in methane levels detected by Curiosity and the Trace Gas Orbiter (an open question since 2016), although it does not explain what is creating the methane or why the methane seems to be more short-lived than current models predict.
On 3 July 2021, the Curiosity rover viewed the "Rafael Navarro Mountain" area.
On 1 November 2021, astronomers reported detecting, in a "first-of-its-kind" process based on SAM instruments, organic molecules, including benzoic acid, ammonia and other related unknown compounds, on the planet Mars by the Curiosity rover.
On 17 January 2022, scientists reported finding an unusual signal of carbon isotopes on Mars by the Curiosity rover which may (or may not) be associated with ancient Martian life and suggesting, according to the scientists, that microbes residing underground may have emitted the "enriched carbon as methane gas". However, abiotic sources of the unusual carbon signal have not been completely ruled out.
In April 2022, Mars Science Laboratory was renewed for a fourth extended mission, which will include the exploration of the sulfate-bearing unit.
Fourth extended mission (October 2022 - Present)
The rover began its fourth extended mission on 1 October 2022, which will last until October 2025.
In January 2023, the Curiosity Rover viewed and studied the "Cacao" meteorite.
In August 2023, Curiosity explored the upper Gediz Vallis Ridge. A panoramic view of the ridge is here, and a 3D rendered view is here.
In February 2024, Curiosity completed its 40th successful drilling, of a rock named "Mineral King" in Gediz Vallis.
In July 2024, it was announced that, in an analysis of a rock that had been crushed by the rover (one in a series of deposits), elemental pure sulfur had been found on Mars for the first time.
In October 2024, the science team behind the SAM experiment onboard the rover announced the results of three years of sampling, which suggested that based on high carbon-13 and oxygen-18 levels in the regolith, the early Martian atmosphere was unlikely to be stable enough to support surface water hospitable to life, with rapid wetting-drying cycles and very high-salinity cryogenic brines providing an explanation.
Current status
Weather
Current Weather Report on Mars by the Curiosity rover
Current Weather Report on Mars by the InSight lander
Current Weather Report on Mars by the Perseverance rover
Location and travel statistics
This up-to-date NASA link shows Curiosity travels and present location
As of , , Curiosity has been on the planet Mars for sols ( total days) since landing on 6 August 2012. Since 11 September 2014, Curiosity has been exploring the slopes of Mount Sharp, where more information about the history of Mars is expected to be found. As of 26 January 2021, the rover has traveled over and climbed over in elevation to, and around, the mountain base since arriving at Bradbury Landing in August 2012.
Equipment status
Since early 2015, the percussive mechanism in the drill that chisels into rock has had an intermittent electrical short circuit.
In December 2016, the motor inside the drill caused a malfunction that prevented the rover from moving its robotic arm and driving to another location. The fault is in the drill feed motor - internal debris is suspected. The fault was determined to be limited to the drill mechanism and the rover started moving again on 9 December. The robotic arm is functional, and the Curiosity team performed diagnostics on the drill mechanism throughout 2017. On 4 June 2018, NASA announced that Curiosity ability to drill has been sufficiently restored by changing the drilling methods.
Since 15 September 2018, a glitch in Curiosity's active computer (Side-B) has prevented Curiosity from storing science and key engineering data. On 3 October 2018, the JPL began operating Curiosity on its backup computer (Side-A). Curiosity will store science and engineering data normally using its Side-A computer until the cause of the glitch in Side-B is determined and remedied.
Self-Portraits
See also
Aeolis quadrangle
Astrobiology
Composition of Mars
ExoMars programme
Exploration of Mars
Geography of Mars
Geology of Mars
InSight lander
Life on Mars
List of missions to Mars
List of rocks on Mars
Mars Exploration Rover
Mars Express orbiter
Mars Odyssey Orbiter
Mars Orbiter Mission
Mars Pathfinder (Sojourner rover)
Mars Reconnaissance Orbiter
Mars 2020 rover mission
MAVEN orbiter
Moons of Mars
Phoenix lander
Robotic spacecraft
Scientific information from the Mars Exploration Rover mission
Space exploration
Timeline of Mars 2020
U.S. Space Exploration History on U.S. Stamps
Viking program
Water on Mars
References
External links
Curiosity Rover Official Page.
MSL/NASA Official Page.
Mars Weather: Perseverance*Curiosity*InSight
Curiosity Rover Tracker (6 August 2012 to 5 August 2013 and beyond).
Panoramic View of Gale Crater on Mars (4 billion pixels) (March 2013).
Video (04:32) - Evidence for 'Vigorously' Flowing Water on Ancient Mars (September 2012).
Video (02:52) - Curiosity view from Mount Sharp (NASA; August 2021)
STScI Webcast Catalog and Archive - (Robert Hazen; NASA; April 2014).
Video (86:49) - Search for Life in the Universe - (NASA; July 2014).
Astrobiology
Exploration of Mars
Mars Science Laboratory
Mars Science Laboratory
Mars Science Laboratory
Articles containing video clips | Timeline of Mars Science Laboratory | Astronomy,Biology | 8,507 |
17,384,208 | https://en.wikipedia.org/wiki/In%20Good%20King%20Charles%27s%20Golden%20Days | In Good King Charles's Golden Days is a play by George Bernard Shaw, subtitled A True History that Never Happened.
It was written in 1938-39 as an "educational history film" for film director Gabriel Pascal in the aftermath of Pygmalions cinema triumph. The cast of the proposed film were to be sumptuously clothed in 17th century costumes, far beyond the resources of most theatre managements. However, by the time of its completion in May 1939, it had turned into a Shavian Restoration comedy.
The title of the play is taken from the first line of the traditional song "The Vicar of Bray".
Plot
The setting is the English court during the reign of Charles II (). A discussion play, the issues of nature, science, power and leadership are debated between Charles ("Mr Rowley"), Isaac Newton, George Fox, and the artist Godfrey Kneller, with interventions by three of the king's mistresses (Barbara Villiers, Louise de Kérouaille, and Nell Gwynn). The short second act involves Charles in conversation with his queen, Catherine of Braganza.
Original production
Billed as "A history lesson in three scenes by Bernard Shaw", the first production was at the Malvern Festival Theatre on 12 August 1939, directed by H. K. Ayliff and designed by Paul Shelving.
Cast:
Mrs Basham: Isobel Thornton
Sally: Betty Marsden
Isaac Newton: Cecil Trouncer
George Fox: Herbert Lomas
Mr Rowley (Charles II): Ernest Thesiger
Nell Gwynn: Eileen Beldon
Barbara Villiers; Daphne Heard
Louise de Kérouaille: Ina De La Haye
James, Duke of York: William Hutchison
Godfrey Kneller: Alec Clunes
Catherine of Braganza: Irene Vanbrugh
Ayliff's production first transferred to the Streatham Hill Theatre on 15 April 1940, then to the New Theatre in London on 9 May 1940.
James Agate, writing for The Sunday Times, noted that the play was the best to have "come from the Shavian loom since Methuselah".
Revivals
Ernest Thesiger, who again played "Mr Rowley", revived the play at the Malvern Festival on 11 August 1949. It was also revived at the Malvern Festival Theatre in 1983.
A radio production was broadcast on the BBC Third Programme on September 18, 1949, with Abraham Sofaer in the title role.
The first North American production was on 24 January 1957 at the Downtown Theater on New York's East 4th Street, where it ran for nearly two years, one of the longest runs of any Shaw play in the USA (as noted by Lawrence Langner).
A BBC production in the Play of the Month series, starring Sir John Gielgud as King Charles, was broadcast in February 1970.
References
In Good King Charles's Golden Days by Bernard Shaw, with 12 text illustrations by Feliks Topolski, Constable, London (1939)
File on Shaw, compiled by Margery Morgan, Methuen, London (1989)
Bernard Shaw, a biography by Michael Holroyd in five volumes, Chatto and Windus (1988-1992)
Shaw's preface to the play, first published in the collected edition of Geneva, Cymbeline Refinished and In Good King Charles's Golden Days, Constable (1947)
Bernard Shaw: The Complete Prefaces, volume III, 1930–1950, edited by Dan H Laurence and Daniel J Leary, Allen Lane, The Penguin Press (1997)
1939 plays
Plays set in the 17th century
Plays by George Bernard Shaw
Cultural depictions of Isaac Newton
Cultural depictions of Charles II of England
Cultural depictions of Barbara Palmer, 1st Duchess of Cleveland
Cultural depictions of Louise de Kérouaille, Duchess of Portsmouth
Cultural depictions of Nell Gwyn
Cultural depictions of Catherine of Braganza | In Good King Charles's Golden Days | Astronomy | 785 |
32,998,830 | https://en.wikipedia.org/wiki/Narumi%20polynomials | In mathematics, the Narumi polynomials sn(x) are polynomials introduced by given by the generating function
,
See also
Umbral calculus
References
Reprinted by Dover, 2005
Polynomials | Narumi polynomials | Mathematics | 38 |
23,691,205 | https://en.wikipedia.org/wiki/C10H13NO2 | {{DISPLAYTITLE:C10H13NO2}}
The molecular formula C10H13NO2 (molar mass : 179.21 g/mol, exact mass : 179.094629) may refer to:
ALPHA (psychedelic)
Fusaric acid
Homarylamine (methylenedioxymethylphenethylamine)
2,3-Methylenedioxyamphetamine (2,3-MDA)
3,4-Methylenedioxyamphetamine (MDA or 3,4-MDA)
Phenacetin, an analgesic
Phenibut
Phenprobamate, a muscle relaxant
Risocaine
Salsolinol | C10H13NO2 | Chemistry | 148 |
20,728,345 | https://en.wikipedia.org/wiki/Timex%20Sinclair%202050 | The Timex Sinclair 2050 (TS2050) was a computer modem built by Westridge Communications for Timex Sinclair, a joint venture between Sinclair Research and Timex Corporation.
Initially sold under the Timex Sinclair label and with a Timex designed case, it was then labeled Westridge 2050, as Timex exited the computer market when the modem started manufacture. A lot of people bought the modem board and made a custom casing.
The device supports all the Timex Sinclair machines, coming with a cassette containing modem control software for T/S 1000 and T/S 1500 on side A and for T/S 2068 on side B.
It was based on the Intel 8251 USART chip and very slow (300 bit/s). A magazine published a way to modify the modem to convert it to a serial port, allowing users to connect faster modems. At least two bulletin board systems based on the T/S 2068 computer and TS2050 modem existed as of 1988.
References
External links
Timex Computer World
Modems
Timex Group | Timex Sinclair 2050 | Technology | 222 |
139,229 | https://en.wikipedia.org/wiki/Gauss%E2%80%93Bonnet%20theorem | In the mathematical field of differential geometry, the Gauss–Bonnet theorem (or Gauss–Bonnet formula) is a fundamental formula which links the curvature of a surface to its underlying topology.
In the simplest application, the case of a triangle on a plane, the sum of its angles is 180 degrees. The Gauss–Bonnet theorem extends this to more complicated shapes and curved surfaces, connecting the local and global geometries.
The theorem is named after Carl Friedrich Gauss, who developed a version but never published it, and Pierre Ossian Bonnet, who published a special case in 1848.
Statement
Suppose is a compact two-dimensional Riemannian manifold with boundary . Let be the Gaussian curvature of , and let be the geodesic curvature of . Then
where is the element of area of the surface, and is the line element along the boundary of . Here, is the Euler characteristic of .
If the boundary is piecewise smooth, then we interpret the integral as the sum of the corresponding integrals along the smooth portions of the boundary, plus the sum of the angles by which the smooth portions turn at the corners of the boundary.
Many standard proofs use the theorem of turning tangents, which states roughly that the winding number of a Jordan curve is exactly ±1.
A simple example
Suppose is the northern hemisphere cut out from a sphere of radius . Its Euler characteristic is 1. On the left hand side of the theorem, we have and , because the boundary is the equator and the equator is a geodesic of the sphere. Then .
On the other hand, suppose we flatten the hemisphere to make it into a disk. This transformation is a homeomorphism, so the Euler characteristic is still 1. However, on the left hand side of the theorem we now have and , because a circumference is not a geodesic of the plane. Then .
Finally, take a sphere octant, also homeomorphic to the previous cases. Then . Now almost everywhere along the border, which is a geodesic triangle. But we have three right-angle corners, so .
Interpretation and significance
The theorem applies in particular to compact surfaces without boundary, in which case the integral
can be omitted. It states that the total Gaussian curvature of such a closed surface is equal to 2 times the Euler characteristic of the surface. Note that for orientable compact surfaces without boundary, the Euler characteristic equals , where is the genus of the surface: Any orientable compact surface without boundary is topologically equivalent to a sphere with some handles attached, and counts the number of handles.
If one bends and deforms the surface , its Euler characteristic, being a topological invariant, will not change, while the curvatures at some points will. The theorem states, somewhat surprisingly, that the total integral of all curvatures will remain the same, no matter how the deforming is done. So for instance if you have a sphere with a "dent", then its total curvature is 4 (the Euler characteristic of a sphere being 2), no matter how big or deep the dent.
Compactness of the surface is of crucial importance. Consider for instance the open unit disc, a non-compact Riemann surface without boundary, with curvature 0 and with Euler characteristic 1: the Gauss–Bonnet formula does not work. It holds true however for the compact closed unit disc, which also has Euler characteristic 1, because of the added boundary integral with value 2.
As an application, a torus has Euler characteristic 0, so its total curvature must also be zero. If the torus carries the ordinary Riemannian metric from its embedding in , then the inside has negative Gaussian curvature, the outside has positive Gaussian curvature, and the total curvature is indeed 0. It is also possible to construct a torus by identifying opposite sides of a square, in which case the Riemannian metric on the torus is flat and has constant curvature 0, again resulting in total curvature 0. It is not possible to specify a Riemannian metric on the torus with everywhere positive or everywhere negative Gaussian curvature.
For triangles
Sometimes the Gauss–Bonnet formula is stated as
where is a geodesic triangle. Here we define a "triangle" on to be a simply connected region whose boundary consists of three geodesics. We can then apply GB to the surface formed by the inside of that triangle and the piecewise boundary of the triangle.
The geodesic curvature the bordering geodesics is 0, and the Euler characteristic of being 1.
Hence the sum of the turning angles of the geodesic triangle is equal to 2 minus the total curvature within the triangle. Since the turning angle at a corner is equal to minus the interior angle, we can rephrase this as follows:
The sum of interior angles of a geodesic triangle is equal to plus the total curvature enclosed by the triangle:
In the case of the plane (where the Gaussian curvature is 0 and geodesics are straight lines), we recover the familiar formula for the sum of angles in an ordinary triangle. On the standard sphere, where the curvature is everywhere 1, we see that the angle sum of geodesic triangles is always bigger than .
Special cases
A number of earlier results in spherical geometry and hyperbolic geometry, discovered over the preceding centuries, were subsumed as special cases of Gauss–Bonnet.
Triangles
In spherical trigonometry and hyperbolic trigonometry, the area of a triangle is proportional to the amount by which its interior angles fail to add up to 180°, or equivalently by the (inverse) amount by which its exterior angles fail to add up to 360°.
The area of a spherical triangle is proportional to its excess, by Girard's theorem – the amount by which its interior angles add up to more than 180°, which is equal to the amount by which its exterior angles add up to less than 360°.
The area of a hyperbolic triangle, conversely is proportional to its defect, as established by Johann Heinrich Lambert.
Polyhedra
Descartes' theorem on total angular defect of a polyhedron is the piecewise-linear analog:
it states that the sum of the defect at all the vertices of a polyhedron which is homeomorphic to the sphere is 4. More generally, if the polyhedron has Euler characteristic (where is the genus, the "number of holes"), then the sum of the defect is .
This is the special case of Gauss–Bonnet in which the curvature is concentrated at discrete points (the vertices). Thinking of curvature as a measure rather than a function, Descartes' theorem is Gauss–Bonnet where the curvature is a discrete measure, and Gauss–Bonnet for measures generalizes both Gauss–Bonnet for smooth manifolds and Descartes' theorem.
Combinatorial analog
There are several combinatorial analogs of the Gauss–Bonnet theorem. We state the following one. Let be a finite 2-dimensional pseudo-manifold. Let denote the number of triangles containing the vertex . Then
where the first sum ranges over the vertices in the interior of , the second sum is over the boundary vertices, and is the Euler characteristic of .
Similar formulas can be obtained for 2-dimensional pseudo-manifold when we replace triangles with higher polygons. For polygons of vertices, we must replace 3 and 6 in the formula above with and , respectively.
For example, for quadrilaterals we must replace 3 and 6 in the formula above with 2 and 4, respectively. More specifically, if is a closed 2-dimensional digital manifold, the genus turns out
where indicates the number of surface-points each of which has adjacent points on the surface. This is the simplest formula of Gauss–Bonnet theorem in three-dimensional digital space.
Generalizations
The Chern theorem (after Shiing-Shen Chern 1945) is the -dimensional generalization of GB (also see Chern–Weil homomorphism).
The Riemann–Roch theorem can also be seen as a generalization of GB to complex manifolds.
A far-reaching generalization that includes all the abovementioned theorems is the Atiyah–Singer index theorem.
A generalization to 2-manifolds that need not be compact is Cohn-Vossen's inequality.
In popular culture
In Greg Egan's novel Diaspora, two characters discuss the derivation of this theorem.
The theorem can be used directly as a system to control sculpture - for example, in work by Edmund Harriss in the collection of the University of Arkansas Honors College.
See also
Chern–Gauss–Bonnet theorem
Atiyah–Singer index theorem
References
Further reading
External links
Gauss–Bonnet Theorem at Wolfram Mathworld
Theorems in differential geometry
Riemann surfaces | Gauss–Bonnet theorem | Mathematics | 1,805 |
20,754,801 | https://en.wikipedia.org/wiki/B%C3%B8rge%20Jessen | Børge Christian Jessen (19 June 1907 – 20 March 1993) was a Danish mathematician best known for his work in analysis, specifically on the Riemann zeta function, and in geometry, specifically on Hilbert's third problem.
Early years
Jessen was born on 19 June 1907 in Copenhagen to Hans Jessen and Christine Jessen (née Larsen). He attended Skt. Jørgens Gymnasium, where he was taught by the Hungarian mathematician Julius Pal during his first year. In 1925, Jessen graduated from the gymnasium and enrolled at the University of Copenhagen. During his time at the university he got to know Harald Bohr, then a leading figure in Danish mathematics. In 1928, Bohr established a collaboration with Jessen, which would last until Bohr's death in 1951.
After receiving his master's degree in the spring of 1929, Jessen embarked on a stay abroad. Supported by the Carlsberg Foundation, he spent the fall of 1929 at the University of Szeged, where he met Frigyes Riesz, Alfréd Haar, and Lipót Fejér. He then spent the winter semester of 1929–30 at the University of Göttingen, where he attended lectures by David Hilbert and Edmund Landau while working on his PhD thesis. On 1 May 1930 Jessen defended his thesis in Copenhagen. He later elaborated the thesis into an article that was published in Acta Mathematica in 1934. The same year, he was appointed as a docent at The Royal Veterinary and Agricultural University in Denmark.
In 1931, Jessen married Ellen Pedersen (1903–1979), cand. mag. in mathematics and the daughter of Peder Oluf Pedersen. Jessen continued to travel frequently in the early 1930s, visiting Paris, Cambridge, England, the Institute for Advanced Study, Yale and Harvard University in America.
Career
Jessen was a professor of descriptive geometry at the Technical University of Denmark from 1935 till 1942, when he moved back to the University of Copenhagen where he was professor from 1942 to 1977 when he retired. He was the president of the Carlsberg Foundation in 1955-1963 and one of the founders of the Hans Christian Ørsted Institute. He was the Secretary of the Interim Executive Committee of the International Mathematical Union (1950–1952), and in September 1951 he officially declared the founding of the Union, with its first domicile in Copenhagen. He was also active in the Danish Mathematical Society. After his death, the society named an award in his honor (Børge Jessen Diploma Award).
See also
Jessen's icosahedron
Jessen–Wintner theorem
References
External links
Bernard Bru and Salah Eid "Jessen’s theorem and Lévy’s lemma" in JEHPS June 2009
A short biography
1907 births
1993 deaths
Scientists from Copenhagen
Danish mathematicians
20th-century Danish mathematicians
University of Copenhagen alumni
Academic staff of the University of Copenhagen
Mathematical analysts
Geometers
Institute for Advanced Study visiting scholars | Børge Jessen | Mathematics | 599 |
11,818,665 | https://en.wikipedia.org/wiki/Endothiella%20gyrosa | Endothiella gyrosa is a plant pathogen.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Diaporthales
Fungi described in 1906
Fungus species | Endothiella gyrosa | Biology | 42 |
19,268,700 | https://en.wikipedia.org/wiki/Membranome | Membranome is the set of biological membranes existing in a specific organism. The term was proposed by British biologist Thomas Cavalier-Smith to discuss epigenetics of biological membranes. The term was also used to define the entire set of membrane proteins in an organism or a combination of membrane proteome and lipidome.
References
See also
Membranome database
Membrane biology
Omics | Membranome | Chemistry,Biology | 80 |
16,877,125 | https://en.wikipedia.org/wiki/Automated%20tank%20cleaning%20machine | An automated tank cleaning machine is a machine used to clean cargo, process, underground storage tanks and similar equipment such as those found in tank trucks, railroad cars, barges, oil tankers, food and beverage manufacturing facilities, chemical processing plants, ethanol plants, and brewing facilities. Genericized trademarks such as Gamajet and Butterworth machine are often used to refer to automatic tank cleaning machines regardless of their manufacturer.
Operation
Tanks must be cleaned from time to time for various reasons. One reason is to change the type of product carried inside a tank to prevent cross contamination. Another is to allow the tank to be inspected or for maintenance to be performed within a tank and to prevent product build-up on tank interior walls.
Automated tank cleaning machines work in a manner similar to an irrigation sprinkler but are highly-engineered to deliver increased force. Water forced through rotary jet nozzles rotates the device on a dual axis, creating a 360° cleaning pattern. As the water sprays, the liquid is pumped out of the tank. Portable cleaning systems are commonly used for many outdoor applications while fixed or permanent Clean-in-Place (CIP) systems are used in more sanitary environments.
The Alfa Laval Gamajet 8 is widely used in the chemical industry, ethanol, transport, brewing, municipality, and oilfield/fuel storage applications. Weighing only 15 lbs., the device maintains 40 lbs. of cleaning force at 25 feet. Typical cleaning cycles are completed in 12 minutes.
The Butterworth Type K machine is widely used. This model can clean a tank of up to . It uses water with a pressure up to and a temperature of up to . The water jet reaches up to . Depending on the pressure used, a cleaning cycle can take from about 10 to 50 minutes and the machine uses between and per minute.
On most crude-oil tankers, a special crude oil washing system, or COW system, is part of the cleaning process. The COW system circulates hot crude oil through the fixed tank-cleaning system to remove wax and asphaltic deposits.
Although machines are often used to wash tanks, a final stage of manual cleaning known as mucking, is usually performed. Mucking requires protocols for entry into confined spaces and the use of airline respirators, protective clothing and safety observers.
However, with Gamajet tank cleaning machines, confined space entry is greatly reduced eliminating danger to workers. Manual tank cleaning is dangerous in a number of ways. While tank barges can be cleaned in port, shipboard tanks are generally cleaned at sea. This is largely due to risks of fire and explosion inside the tanks.
History
The first automated tank cleaning machine was invented by Arthur Butterworth and patented in 1920. His goal was to limit the amount of time that workers had to spend inside tanks, and partially relieve them of a dangerous and laborious job. In 1925, Butterworth established a company to market the machine. Standard Oil New Jersey bought the company in 1930, and it later became a subsidiary of the Exxon Corporation.
In 1986, as part of an internal restructuring at Exxon, the Butterworth company was sold to Exxon management. Today the company is privately held, and headquartered in Houston, Texas.
In 2012, Gamajet Cleaning Systems, Inc. was purchased by Alfa Laval to combine two global tank cleaning product lines, Gamajet and Toftejorg. The tank cleaning segment operates in Exton, Pennsylvania.
See also
Oil tanker
Chemical tanker
References
Citations
Petroleum technology
Tankers
Food industry
Storage tanks | Automated tank cleaning machine | Chemistry,Engineering | 713 |
2,168,837 | https://en.wikipedia.org/wiki/Password-based%20cryptography | Password-based cryptography is the study of password-based key encryption, decryption, and authorization. It generally refers two distinct classes of methods:
Single-party methods
Multi-party methods
Single party methods
Some systems attempt to derive a cryptographic key directly from a password. However, such practice is generally ill-advised when there is a threat of brute-force attack. Techniques to mitigate such attack include passphrases and iterated (deliberately slow) password-based key derivation functions such as PBKDF2 (RFC 2898).
Multi-party methods
Password-authenticated key agreement systems allow two or more parties that agree on a password (or password-related data) to derive shared keys without exposing the password or keys to network attack. Earlier generations of challenge–response authentication systems have also been used with passwords, but these have generally been subject to eavesdropping and/or brute-force attacks on the password.
See also
Password
Passphrase
Password-authenticated key agreement
References
Further reading
https://link.springer.com/chapter/10.1007/978-3-642-32009-5_19
https://link.springer.com/chapter/10.1007/978-3-662-46447-2_14
Cryptography | Password-based cryptography | Mathematics,Engineering | 274 |
1,665,120 | https://en.wikipedia.org/wiki/Relvar | In relational databases, relvar is a term introduced by C. J. Date and Hugh Darwen as an abbreviation for relation variable in their 1995 paper The Third Manifesto, to avoid the confusion sometimes arising from the use of the term "relation", by the inventor of the relational model, E. F. Codd, for a variable to which a relation is assigned as well as for the relation itself. The term is used in Date's well-known database textbook An Introduction to Database Systems and in various other books authored or coauthored by him.
Some database textbooks use the term relation for both the variable and the data it contains. Similarly, texts on SQL tend to use the term table for both purposes, though the qualified term base table is used in the standard for the variable.
A closely related term often used in academic texts is relation schema, this being a set of attributes paired with a set of constraints, together defining a set of relations for the purpose of some discussion (typically, database normalization). Constraints that mention just one relvar are termed relvar constraints, so relation schema can be regarded as a single term encompassing a relvar and its relvar constraints.
References
C.J. Date. An Introduction to Database Systems, 8th Ed. (Addison-Wesley, 2004, ), pp. 65–66.
C.J. Date and Hugh Darwen. Databases, Types, and The Relational Model: The Third Manifesto (Addison-Wesley, 2007, ), p.85
Relational model
Data modeling
Databases
Variable (computer science) | Relvar | Engineering | 323 |
191,208 | https://en.wikipedia.org/wiki/Rigoberta%20Mench%C3%BA | Rigoberta Menchú Tum (; born 9 January 1959) is a K'iche' Guatemalan human rights activist, feminist, and Nobel Peace Prize laureate. Menchú has dedicated her life to publicizing the rights of Guatemala's Indigenous peoples during and after the Guatemalan Civil War (1960–1996), and to promoting Indigenous rights internationally.
In 1992 she received the Nobel Peace Prize, became an UNESCO Goodwill Ambassador, and received the Prince of Asturias Award in 1998. Menchú is also the subject of the testimonial biography I, Rigoberta Menchú (1983) author of the autobiographical work, Crossing Borders (1998), and is subject interest among other works. Menchú founded the country's first indigenous political party, Winaq; and ran for president of Guatemala in 2007 and 2011, having founded the country's first Indigenous political party,
Personal life
Rigoberta Menchú was born to a poor Indigenous family of K'iche' Maya descent in Laj Chimel, a rural area in the north-central Guatemalan province of El Quiché. Her family was one of many Indigenous families who could not sustain themselves on the small pieces of land they were left with after the Spanish conquest of Guatemala. Menchú's mother began her career as a midwife at age sixteen and continued to practice using traditional medicinal plants until she was murdered at age 43. Her father was a prominent activist for the rights of Indigenous farmers in Guatemala. Both of her parents regularly attended Catholic church, but her mother remained connected to her Maya spirituality and identity. She believes in many teachings of the Catholic Church, but her mother's Maya influence also taught Menchú the importance of living in harmony with nature and retaining her Maya culture. Menchú considers herself to be the perfect mix of both her parents.
In 1979–80, Menchú's brother, Patrocinio, and mother, Juana Tum Kótoja, were kidnapped, brutally tortured and murdered by the Guatemalan Army. Her father, Vicente Menchú Perez, died in the 1980 Burning of the Spanish Embassy, which occurred after urban guerrillas took hostages and were attacked by government security forces. In January 2015, Pedro García Arredondo, a former police commander of the Guatemalan Army who later served as the chief of the now defunct National Police (Policía Nacional, PN), was convicted of attempted murder and crimes against humanity for his role in the embassy attack; Arrendondo was also previously convicted in 2012 of ordering the enforced disappearance of agronomy student Édgar Enrique Sáenz Calito during the country's long-running internal armed conflict.
In 1984, Menchú's other brother, Victor, was shot to death after he surrendered to the Guatemalan Army, was threatened by soldiers, and tried to escape.
In 1995, Menchú married Ángel Canil, a Guatemalan, in a Mayan ceremony. They had a Catholic wedding in January 1998; at that time they also buried their son Tz'unun ("hummingbird" in K’iche’ Maya), who had died after being born prematurely in December. They adopted a son, Mash Nahual Ja' ("Spirit of Water").
Menchú featured prominently in the 1983 documentary When the Mountains Tremble, directed by Newton Thomas Sigel and Pamela Yates.
She lives with her family in the municipality of San Pedro Jocopilas, Quiché Department, northwest of Guatemala City, in the heartland of the Kʼicheʼ people.
Connections to the Guatemalan civil war
Following military coups that started with the CIA-orchestrated removal of President Jacobo Arbenz in Guatemala in 1954, the Cuban revolution of 1959, and the Che Guevara's commitment to create as many Vietnams as he could, the U.S. moved to condone and often support authoritarian rule in the name of national security. The Guatemalan Civil War lasted from 1962 to 1996 and was provoked by social, economic, and political inequality. An estimated 250,000 people were assassinated, including 50,000 desaparecidos, and hundreds of thousands of displaced individuals, either at the hands of the armed forces or the militarized civilians knows as Patrullas de Autodefensa Civil (Civil Defense Patrols). This made people nervous since arming civilians, let alone Indians, was not a very common occurrence in Guatemala and was, in fact, illegal according to the country's constitution.
Massacres of Indian men, women, and children in Guatemala began in May 1978, a stone's throw away from a major Canadian nickel, culminating in 1982. By 1981 the US Central Intelligence Agency (CIA) was reporting on the indiscriminate killing of civilians in rural areas, government soldiers being "forced to fire at anything that moved". In 1982 the CIA reported several villages being burned to the ground while Guatemalan commanding officers were "expected to give no quarter to combats and non-combats alike".
These inequalities were most impactful on marginalized populations, especially indigenous communities. To maintain order, the state implemented forceful measures that often, violated human rights. This ultimately led to mass genocide, disappearances, and displacement of indigenous populations. 83% of victims were later identified as Mayan, indicating that a majority of human rights violated were those of the Indigenous communities of Guatemala. These events had a deep impact on Menchú and her family and were the root cause of her activism in Indigenous rights.
Guatemalan activism
From a young age, Menchú was active alongside her father. Together they advocated for the rights of Indigenous farmers through the Committee for Peasant Unity. Menchú often faced discrimination for wanting to join her male family members in the fight for justice, but she was inspired by her mother to continue making space for herself. Menchú believes that the roots of Indigenous oppression in Guatemala stem from issues of exploitation and colonial land ownership, and in her early activism focused on defending her people from colonial exploitation.
After leaving school, Menchú worked as an activist campaigning against human rights violations committed by the Guatemalan Army during the country's civil war, which lasted from 1960 to 1996. Many of the human rights violations that occurred during the war targeted Indigenous peoples. Women were targets of physical and sexual violence at the hands of the military.
In 1981, Menchú was exiled and escaped to Mexico where she found refuge in the home of a Catholic bishop in Chiapas. Menchú continued to organize resistance to oppression in Guatemala and organize the struggle for Indigenous rights by co-founding the United Republic of Guatemalan Opposition. Tens of thousands of people, mostly indigenous Maya people, fled to Mexico from 1982 to 1984 at the height of Guatemala's 36-year civil war.
A year later, in 1982, she narrated a book about her life, titled Me llamo Rigoberta Menchú y así me nació la conciencia (My Name is Rigoberta Menchú, and this is how my Awareness was Born), to Venezuelan author and anthropologist Elizabeth Burgos. The book was translated into five other languages including English and French. Menchú's work made her an international icon at the time of the ongoing conflict in Guatemala and brought attention to the suffering of Indigenous peoples under an oppressive government regime.
Menchú served as the Presidential Goodwill Ambassador for the 1996 Peace Accords in Guatemala. That same year she received the Peace Abbey Courage of Conscience Award in Boston.
After the Guatemalan Civil War ended, Menchú campaigned to have Guatemalan political and military establishment members tried in Spanish courts. In 1999, she filed a complaint before a court in Spain because prosecutions of civil-war era crimes in Guatemala was practically impossible. These attempts stalled as the Spanish courts determined that the plaintiffs had not yet exhausted all possibilities of seeking justice through the legal system of Guatemala. On 23 December 2006, Spain called for the extradition from Guatemala of seven former members of Guatemala's government, including Efraín Ríos Montt and Óscar Mejía, on charges of genocide and torture. Spain's highest court ruled that cases of genocide committed abroad could be judged in Spain, even if no Spanish citizens were involved. In addition to the deaths of Spanish citizens, the most serious charges include genocide against the Maya people of Guatemala.
Politics
In 2005, Menchú joined the Guatemalan federal government as goodwill ambassador for the National Peace Accords. Menchú faced opposition and discrimination. In April 2005, five Guatemalan politicians would be convicted for hurling racial epithets at Menchú. Court rulings would also uphold the right to wear indigenous dresses and practice Mayan spirituality.
On 12 February 2007, Menchú announced that she would form an Indigenous political party called Encuentro por Guatemala and that she would stand in the 2007 presidential election. She was the first Maya, Indigenous woman to ever run in a Guatemalan election. In the 2007 election, Menchú was defeated in the first round, receiving three percent of the vote.
In 2009, Menchú became involved in the newly founded party Winaq. Menchú was a candidate for the 2011 presidential election, but lost in the first round, winning three percent of the vote again. Although Menchú was not elected, Winaq succeeded in becoming the first Indigenous political party of Guatemala.
International activism
At the peak of state counterinsurgency, the Permanent Peoples’ Tribunal: Session on Guatemala (PPT-SG), held in Madrid in 1983, was the first of its kind for Central America. The tribunal looked at evidence going back to the CIA-backed coup that ousted democratically elected president Jacobo Árbenz in 1954; although its focus was on the massacres, scorched earth policies, forced disappearances, torture, and killings taking place at the time under General Efraín Ríos Montt. Menchú was included in the five-day tribunal, that included twenty-two testifiers, and shared how her mother was used as bait as an effort to trap her children:
Almost thirty years later, the First Tribunal of Consciousness Against Sexual Violence Toward Women took place in Guatemala City in 2010. The 1983 PPT-SG did not acknowledge the rape of women, particularly Maya women, during the armed conflict testifiers spoke; but it would take another twenty-seven years for sexual violence to be fully recognized in an ethical tribunal, and thirty-three years for it to be legally condemned in 2016 in the Sepur Zarco case. The trial and conviction of Jose Efrain Rios Montt in Guatemala in 2013 demonstrates that 15 years later, it is possible to convict a former head of state of crimes against humanity. Guatemala became the first Latin America country to place a former president on trial for genocide, being charged for the killing and disappearance of 70,000 people and the displacement of hundreds of thousands.
In 1996, Menchú was appointed as a UNESCO Goodwill Ambassador in recognition of her activism for the rights of Indigenous people. In this capacity, she acted as a spokesperson for the first International Decade of the World's Indigenous Peoples (1995–2004), where she worked to improve international collaboration on issues such as environment, education, health care, and human rights for Indigenous peoples. In 2015, Menchú met with the general director of UNESCO, Irina Bokova, in order to solidify relations between Guatemala and the organization.
Since 2003, Menchú has become involved in the Indigenous pharmaceutical industry as president of "Salud para Todos" ("Health for All") and the company "Farmacias Similares," with the goal of offering low-cost generic medicines. As president of this organization, Menchú has received pushback from large pharmaceutical companies due to her desire to shorten the patent life of certain AIDS and cancer drugs to increase their availability and affordability.
In 2006, Menchú was one of the founders of the Nobel Women's Initiative along with sister Nobel Peace Laureates Jody Williams, Shirin Ebadi, Wangari Maathai, Betty Williams and Mairead Corrigan Maguire. These six women, representing North America, South America, Europe, the Middle East, and Africa, decided to bring together their experiences in a united effort for peace, justice and equality. It is the goal of the Nobel Women's Initiative to help strengthen women's rights around the world.
Menchú is a member of PeaceJam, an organization whose mission is to use Nobel Peace Laureates as mentors and models for young people and provide a way for these Laureates to share their knowledge, passions, and experience. She travels around the world speaking to youth through PeaceJam conferences. She has also been a member of the Foundation Chirac's honor committee since the foundation was launched in 2008 by former French president Jacques Chirac in order to promote world peace.
Menchú has continued her activism by continuing to raise awareness for issues including political and economic inequality and climate change.
Legacy
Awards and honors
1992 Nobel Peace Prize for her advocacy and social justice work for the indigenous peoples of Latin America
1992 UNESCO Goodwill Ambassador position for her advocacy for the indigenous peoples of Guatemala
Menchú was the youngest recipient of the Nobel Peace Prize at the time, and the first indigenous people recipient.
1996 Peace Abbey Courage of Conscience Award for her authorship and advocacy for the indigenous peoples of Guatemala
1998 Prince of Asturias Prize for improving the condition of women and the communities they serve. (Jointly with 6 other women.)
1999 asteroid 9481 Menchú was named in her honor ()
2010 Order of the Aztec Eagle for services provided for Mexico
2018 Spendlove Prize for her advocacy for minority groups
In 2022, the University of Bordeaux Montaigne, located in Pessac, gave her name to its newly built library in her honor.
Publications
I, Rigoberta Menchú (1983)
This book, also titled My Name is Rigoberta Menchú and that's how my Conscience was Born, was dictated by Menchú and transcribed by Elizabeth Burgos
Crossing Borders (1998) Daughter of the Maya (1999)
The Girl from Chimel (2005) with Dante Liano, illustrated by Domi
The Honey Jar (2006) with Dante Liano, illustrated by Domi
The Secret Legacy (2008) with Dante Liano, illustrated by Domi K'aslemalil-Vivir. El caminar de Rigoberta Menchú Tum en el Tiempo (2012)
Testimony controversy
More than a decade after the publication of I, Rigoberta Menchú, anthropologist David Stoll investigated Menchú's story and claimed that Menchú changed some elements about her life, family, and village to meet the publicity needs of the guerrilla movement. Stoll acknowledged the violence against the Maya civilians in his book, Rigoberta Menchu and the Story of all Poor Guatemalans, but believed the guerillas were responsible for the army's atrocities. The controversy caused by Stoll's book received widespread coverage in the US press of the time; thus the New York Times highlighted a few claims in her book contradicted by other sources:
Many authors have defended Menchú, and attributed the controversy to different interpretations of the testimonio genre.Sanford, Victoria PhD. "The Silencing of Maya Women From Mama Maquin to Rigoberta Menchu", pp. 135–143 [142], for critique on Stoll's informant, Alfonso Riviera. Menchú herself states, "I'd like to stress that it's not only my life, it's also the testimony of my people." An error in Rigoberta Menchu and the Story of all Poor Guatemalans is Stoll's representation of the massacre at the Spanish embassy in Guatemala in 1980 as a self-immolation coordinated by student and indigenous leaders of the peasant protesters occupying the embassy; investigators in 1981 reported on the massacre and the La Comisión para el Esclarecimiento Histórico (Commission for the Historical Clarification-CEH) and published findings concluding that the army carried out a premeditated firebombing of the embassy.
Later, a declassified CIA document form late February 1982 states that in mid-February 1982 the Guatemalan army reinforced its existing forces and launched a "sweep operation in the Ixil Triangle; and commanding officers of the units involved had been instructed to destroy all towns and villages which were cooperating in the Guerilla Army of the Poor (EGP) and eliminate all sources of resistance." Which was a fallacy recently repeated in the Times Literary Supplement by Ilan Stavans in his review of Stoll's book. Some scholars have stated that, despite its factual and historical inaccuracies, Menchú's testimony remains relevant for the ways in which it depicts the life of an Indigenous Guatemalan during the civil war.
The Nobel Committee dismissed calls to revoke Menchú's Nobel Prize, in spite of Stoll's allegations regarding Menchú. Geir Lundestad, the secretary of the committee, stated that Menchú's prize was awarded because of her advocacy and social justice work, not because of her testimony, and that she had committed no observable wrongdoing.
According to Mark Horowitz, William Yaworsky, and Kenneth Kickham, the controversy about Stoll's account of Menchu is one of the three most divisive episodes in recent American anthropological history, along with controversies about the truthfulness of Margaret Mead's Coming of Age in Samoa and Napoleon Chagnon's representation of violence among the Yanomami.
See also
List of civil rights leaders
List of peace activists
List of female Nobel laureates
List of feminists
References
Bibliography
Ament, Gail. "Recent Maya Incursions into Guatemalan Literary Historiography". Literary Cultures of Latin America: A Comparative History. Eds. Mario J. Valdés & Djelal Kadir. 3 Vols. Vol 1: Configurations of Literary Culture. Oxford: Oxford University Press, 2004: I: 216–215.
Arias, Arturo. "After the Rigoberta Menchú Controversy: Lessons Learned About the Nature of Subalternity and the Specifics of the Indigenous Subject" MLN 117.2 (2002): 481–505.
Beverley, John. "The Real Thing (Our Rigoberta)" Modern Language Quarterly 57:2 (June 1996): 129–235.
Brittin, Alice A. "Close Encounters of the Third World Kind: Rigoberta Menchu and Elisabeth Burgos's Me llamo Rigoberta Menchu". Latin American Perspectives, Vol. 22, No. 4, Redefining Democracy: Cuba and Chiapas (Autumn, 1995), pp. 100–114.
De Valdés, María Elena. "The Discourse of the Other: Testimonio and the Fiction of the Maya." Bulletin of Hispanic Studies (Liverpool), LXXIII (1996): 79–90.
Feal, Rosemary Geisdorfer. "Women Writers into the Mainstream: Contemporary Latin American Narrative". Philosophy and Literature in Latin America. Eds. Jorge J.E. Gracia and Mireya Camurati. New York: State University of New York, 1989. An overview of women in contemporary Latin American letters.
Golden, Tim. "Guatemalan Indian Wins the Nobel Peace Prize": New York Times (17 October 1992): p. A1, A5.
Golden, Tim. "Guatemalan to Fight on With Nobel as Trumpet": New York Times (19 October 1992): p. A5.
Gossen, Gary H. "Rigoberta Menchu and Her Epic Narrative". Latin American Perspectives, Vol. 26, No. 6, If Truth Be Told: A Forum on David Stoll's "Rigoberta Menchu and the Story of All Poor Guatemalans" (Nov., 1999), pp. 64–69.
Gray Díaz, Nancy. "Indian Women Writers of Spanish America". Spanish American Women Writers: A Bio-Bibliographical Source Book. Ed. Diane E. Marting. New York: Greenwood Press, 1988
Millay, Amy Nauss. Voices from the Fuente Viva: The Effect of Orality in Twentieth-Century Spanish American Narrative. Lewisburg: Bucknell University Press, 2005.
Logan, Kathleen. "Personal Testimony: Latin American Women Telling Their Lives". Latin American Research Review 32.1 (1997): 199–211. Review Essay.
Nelan, Bruce W. "Striking Against Racism". Time 140:61 (26 October 1992): p. 61.
Stanford, Victoria. "Between Rigoberta Menchu and La Violencia: Deconstructing David Stoll's History of Guatemala" Latin American Perspectives 26.6, If Truth Be Told: A Forum on David Stoll's "Rigoberta Menchu and the Story of All Poor Guatemalans" (Nov., 1999), pp. 38–46.
---. "From I, Rigoberta to the Commissioning of Truth Maya Women and the Reshaping of Guatemalan History". Cultural Critique 47 (2001) 16–53.
Sommer, Doris. "Rigoberta's Secrets" Latin American Perspectives, Vol. 18, No. 3, Voices of the Voiceless in Testimonial Literature, Part I. (Summer, 1991), pp. 32–50.
Stoll, David "Rigoberta Menchu and the Story of All Poor Guatemalans" (Westview Press, 1999)
---. "Slaps and Embraces: A Rhetoric of Particularism". The Latin American Subaltern Studies Reader. Ed. Iliana Rodríguez. Durham: Duke University Press, 2001.
Wise, R. Todd. "Native American Testimonio: The Shared Vision of Black Elk and Rigoberta Menchú". In Christianity and Literature, Volume 45, Issue No.1 (Autumn 1995).
Zimmerman, Marc. "Rigoberta Menchú After the Nobel: From Militant Narrative to Postmodern Politics". The Latin American Subaltern Studies Reader. Durham: Duke University Press, 2001.
External links
Salon.com: Rigoberta Menchú meets the press
"Peace Prize Winner Admits Discrepancies", AP story in New York Times'', 12 February 1999 (Subscription only.)
"Spain may judge Guatemala abuses", BBC News, 5 October 2005
"Anthropologist Challenges Veracity of Multicultural Icon" – The Chronicle of Higher Education. (Subscription only.)
Sound recording of Elizabeth Burgos-Debray interviewing Rigoberta Menchu.
Guatemalan activists
Guatemalan indigenous rights activists
Guatemalan women human rights activists
Nobel Peace Prize laureates
Guatemalan Nobel laureates
Women Nobel laureates
Women autobiographers
1959 births
Living people
People of the Guatemalan Civil War
Nonviolence advocates
20th-century Guatemalan women politicians
20th-century Guatemalan politicians
Guatemalan Maya people
Indigenous activists of North America
Indigenous writers of the Americas
Encuentro por Guatemala politicians
Winaq politicians
People from Quiché Department
Women in war in Central America
Women in war 1945–1999
20th-century Guatemalan writers
21st-century Guatemalan writers
K'iche' people
Autobiographers
21st-century Guatemalan women politicians
21st-century Guatemalan politicians
20th-century Guatemalan women writers
UNESCO Goodwill Ambassadors
Indigenous feminists of the Americas
Feminism and history
Guatemalan feminists
Indigenous rights
Indigenous rights activists
Guatemalan socialists | Rigoberta Menchú | Technology | 4,772 |
604,725 | https://en.wikipedia.org/wiki/Bluejacking |
Bluejacking is the sending of unsolicited messages over Bluetooth to Bluetooth-enabled devices such as mobile phones, PDAs or laptop computers, sending a vCard which typically contains a message in the name field (i.e., for bluedating) to another Bluetooth-enabled device via the OBEX protocol.
Bluetooth has a very limited range, usually around on mobile phones, but laptops can reach up to with powerful (Class 1) transmitters.
Origins
Bluejacking was reportedly first carried out between 2001 and 2003 by a Malaysian IT consultant who used his phone to advertise Ericsson to a single Nokia 7650 phone owner in a Malaysian bank. He also invented the name, which he claims is an amalgam of Bluetooth and ajack, his username on Esato, a Sony Ericsson fan online forum. Jacking is, however, an extremely common shortening of "hijack', the act of taking over something. Ajack's original posts are hard to find, but references to the exploit are common in 2003 posts.
Another user on the forum claims earlier discovery, reporting a near-identical story to that attributed to Ajack, except they describe bluejacking 44 Nokia 7650 phones instead of one, and the location is a garage, seemingly in Denmark, rather than a Malaysian Bank. Also, the message was an insult to Nokia owners rather than a Sony Ericsson advertisement.
Usage
Bluejacking is usually not very harmful, except that bluejacked people generally don't know what has happened, and so may think that their phone is malfunctioning. Usually, a bluejacker will only send a text message, but with modern phones it's possible to send images or sounds as well. Bluejacking has been used in guerrilla marketing campaigns to promote advergames.
The actual message itself doesn't deploy any malware to the software; rather, it is crafted to elicit a response from the user or add a new contact and can be seen as more of a prank than an attack. These messages can evoke either annoyance or amusement in the recipient. Users typically possess the ability to reject such messages, and this tactic is frequently employed in confined environments such as planes, trains, and buses. However, some forms of DoS Disruptions are still possible, even in modern devices, by sending unsolicited pairing requests in rapid succession; this becomes disruptive because most systems display a full screen notification for every connection request, interrupting every other activity, especially on less powerful devices.
Bluejacking is also confused with Bluesnarfing, which is the way in which mobile phones are illegally hacked via Bluetooth.
Companies
BluejackQ
BlueJackQ is a website dedicated to bluejacking. The website contains a few bluejacking stories taken from the site's forum. The website also includes software that can be used for bluejacking and guides on how to bluejack which are slightly out of date but the basic principle still applies to most makes of phone. Its forum has 4,000 registered users and 93,050 posts. The website has been featured in many news articles.
The forums were opened on the November 13, 2003 and has been the center of BluejackQ from the start. It currently has 4 moderators and has 20 different sections available to members. The areas included information about BluejackQ, reviews of mobile phones, media players, PDAs and Miscellaneous devices, general bluejacking threads and an off-topic area. The BluejackQ podcast was first released as a test version on January 15, 2006, thus becoming the first bluejacking-related podcast. Podcasts 1, 2 and 3 featured three members of the forums.
The forums seem to have been unused since 2020.
Fictional reference in Person of Interest
The authentic bluejacking as described here is not the same exploit which was frequently depicted in the television series Person of Interest; that fictional exploit portrayed different and more invasive capabilities.
See also
Bluebugging
Bluesnarfing
AirDrop
References
Bluetooth
Spamming | Bluejacking | Technology | 826 |
34,149,851 | https://en.wikipedia.org/wiki/Lethargy%20theorem | In mathematics, a lethargy theorem is a statement about the distance of points in a metric space from members of a sequence of subspaces; one application in numerical analysis is to approximation theory, where such theorems quantify the difficulty of approximating general functions by functions of special form, such as polynomials. In more recent work, the convergence of a sequence of operators is studied: these operators generalise the projections of the earlier work.
Bernstein's lethargy theorem
Let be a strictly ascending sequence of finite-dimensional linear subspaces of a Banach space X, and let be a decreasing sequence of real numbers tending to zero. Then there exists a point x in X such that the distance of x to Vi is exactly .
See also
Bernstein's theorem (approximation theory)
References
Theorems in approximation theory | Lethargy theorem | Mathematics | 167 |
56,553,444 | https://en.wikipedia.org/wiki/Katalin%20Vesztergombi | Katalin Vesztergombi (born July 17, 1948) is a Hungarian mathematician known for her contributions to graph theory and discrete geometry. A student of Vera T. Sós and a co-author of Paul Erdős, she is an emeritus associate professor at Eötvös Loránd University and a member of the Hungarian Academy of Sciences.
Education
As a high-school student in the 1960s, Vesztergombi became part of a special class for gifted mathematics students at Fazekas Mihály Gimnázium with her future collaborators László Lovász, József Pelikán, and others. She completed her Ph.D. in 1987 at Eötvös Loránd University. Her dissertation, Distribution of Distances in Finite Point Sets, is connected to the Erdős distinct distances problem and was supervised by Vera Sós.
Contributions
Vesztergombi's research contributions include works on permutations, graph coloring and graph products,
combinatorial discrepancy theory, distance problems in discrete geometry, geometric graph theory,
the rectilinear crossing number of the complete graph, and graphons.
With László Lovász and József Pelikán, she is the author of the textbook Discrete Mathematics: Elementary and Beyond.
Personal
Vesztergombi is married to László Lovász, with whom she is also a frequent research collaborator.
Selected publications
Books
Research articles
References
Living people
20th-century Hungarian mathematicians
21st-century Hungarian mathematicians
Women mathematicians
Graph theorists
Geometers
Academic staff of Eötvös Loránd University
Members of the Hungarian Academy of Sciences
1948 births | Katalin Vesztergombi | Mathematics | 330 |
41,780,237 | https://en.wikipedia.org/wiki/MANIC%20%28cognitive%20architecture%29 | MANIC, formerly known as PMML.1, is a cognitive architecture developed by the predictive modeling and machine learning laboratory at University of Arkansas. It differs from other cognitive architectures in that it tries to "minimize novelty". That is, it attempts to organize well-established techniques in computer science, rather than propose any new methods for achieving cognition. While most other cognitive architectures are inspired by some neurological observation, and are subsequently developed in a top-down manner to behave in some manner like a brain, MANIC is inspired only by common practices in computer science, and was developed in a bottom-up manner for the purpose of unifying various methods in machine learning and artificial intelligence.
Overview
At the highest level, MANIC describes a software agent that, supposedly, will exhibit cognitive intelligence. The agent's artificial brain comprises two major components: a learning system and a decision-making system.
Learning system
The learning system models the agent's environment as a dynamical system. It consists of an "observation function", which maps from the agent's current beliefs to predicted observations, and a "transition function", which maps from current beliefs to future beliefs in the next time-step. The observation function is implemented with a generative deep learning architecture. It is trained in an unsupervised manner from the observations that the agent makes. The intrinsic representations of those observations become the agents "beliefs". The transition function is trained in a supervised manner, to predict the next beliefs from the current ones. The entire learning system is based loosely on a 2011 paper by Michael S. Gashler that describes a method for training a deep neural network to model a simple dynamical system from visual observations.
Decision-making system
The decision-making system consists of a planning module and a contentment function. The planning module uses an evolutionary algorithm to evolve a satisficing plan. The contentment function maps from the agent's current beliefs, or anticipated beliefs, to an evaluation of the utility of being in that state. It is trained by reinforcement from a human teacher. In order to facilitate this reinforcement learning, MANIC provides a mechanism for the agent to generate "fantasy videos" that show anticipated observations if a candidate plan were to be executed. The idea is that a human teacher would evaluate these videos and rank them according to desirability or utility, and the agent could then use that feedback to refine its contentment function.
Sentience
MANIC proposes that the learning system gives the agent awareness of its environment by modeling it, and using that model to anticipate future beliefs. It further proposes that a similar mechanism can also implement sentience. That is, it claims that awareness can be implemented with an outward-looking model, and sentience can be implemented with an inward-looking model. Therefore, it proposes to add "introspective senses", which theoretically give the agent the ability to become aware of its own inner feelings, by modeling them, just as it is aware of its external environment. To some extent, MANIC suggests that existing methods already in use in artificial intelligence are unintentionally creating subjective experiences like those typically associated with conscious beings.
References
External links
http://uaf46365.ddns.uark.edu/lab/cogarch.svg, A poster in SVG format that describes the MANIC architecture.
https://github.com/mikegashler/manic, A Java implementation of MANIC.
Cognitive architecture | MANIC (cognitive architecture) | Engineering | 717 |
1,676,118 | https://en.wikipedia.org/wiki/Euromethod | Euromethod is a method for managing procurement processes of Information Services. It focuses on contract management.
Euromethod consists of three books: a reference manual, a dictionary and a collection of annexes. Euromethod's first release was in 1996.
It has evolved into the Information Services Procurement Library (ISPL), which has published a set of manuals.
History
Euromethod is the result of a European project ordered and funded by DGIII (Industry) of the European Commission. It has been achieved by a consortium containing Sema Group (France), BT Group (UK), Cap-Volmac (The Netherlands), CGI (France), Datacentralen (Denmark), EMSC (Consortium of Bull-Olivetti-Siemens), Finsiel (Italy), INA (Portugal), Indra (Spain), and Softlab (Germany). The project Director was Marcel Franckson.
The reference version has been written in English. It has been translated into French, German, Italian, Spanish, Portuguese, Dutch and Danish.
References
Information technology management
Procurement | Euromethod | Technology | 230 |
22,717,571 | https://en.wikipedia.org/wiki/International%20Committee%20Against%20Racism | The International Committee Against Racism was the "mass organization" of the Progressive Labor Party in the United States. It was founded in 1973 once it had become clear that the Worker Student Alliance section of the Students for a Democratic Society could not sustain itself and that a new group with a more long-term vision not focused on students was going to be needed. Anti-racism was chosen as the focus for that new group.
History
Early leaders of the group included Dr. Robert Kinlock, Toby Schwartz, and Finley Campbell. At first the group took the name "Committee Against Racism" (CAR), but as various Latin American members began to start chapters in their home countries, CAR added "International" to the beginning of its name and became InCAR, proclaiming itself to have not just a U.S. anti-racist focus, but a worldwide one as well.
In 1975 the Committee Against Racism conducted their Summer Project in support of integration and busing in Boston, MA. A joint Freedom School and Petition Campaign culminated in an attempt to have a presence outside South Boston High School on the first day of Phase II busing. Two bus loads of protesters were taken off the buses before reaching the high school, detained and released by police.
By 1978 InCAR had about 1,500 members. It had a magazine periodical for its written work, known as Arrow (Flecha in Spanish), published bilingually.
For the most part, PLP did not bother to hide that it was in charge of InCAR, but it did always choose to frame its role in InCAR as one of "leadership" rather than control. According to PL's party statement: "InCAR is a radical organization led by the Party which the Party builds in order to advance the struggle for communism." InCAR, for its own part, insisted in its mission statement (reprinted on the inside front cover of every Arrow issue) that it "recognizes the absolute necessity of unity of communists and non-communists in this struggle" against both societal and organized racism.
Like PLP as a whole, InCAR was often active in protesting racist rallies held by the Ku Klux Klan, Nazis, and other white supremacists. InCAR sometimes earned fear from these groups: the KKK in the 1980s told the Hartford Courant that "it's because of those commies in InCAR and PLP that our boys are afraid to come out in public wearing their hoods."
Of all the anti-racist actions InCAR took over the years, the best known among the general US public and intellectuals has remained one particular event early in their history having to do with their opposition to sociobiology, made most widely known in recent years by Arthur Jensen, but also involving a few theorists before him. In February 1978 at a symposium held by the American Association for the Advancement of Science, members of InCAR assaulted biologist Edward O. Wilson by rushing the stage chanting, "Racist Wilson you can't hide, we charge you with genocide!" Members then doused Wilson with water. The symposium's moderator Alexander Alland, along with Stephen Jay Gould, took the microphone, apologized to Wilson, and condemned the attack as an inappropriate way to attack sociobiology. Wilson, still wet, gave his speech and received a prolonged standing ovation, but later recalled that after the attack "No one asked them to leave the premises, no police were called, and no action was taken against them later."
InCAR was quietly disbanded in 1996 as PLP decided, for both strategic and financial reasons, to continue InCAR's intense anti-racist work only from within PLP. The party began to argue that itself and InCAR had many duplicate memberships, duplicate or highly similar articles for publication across both the party's newspaper Challenge and InCAR's magazine Arrow, duplicate international chapters similarly containing overlapping memberships, and that all of this was highly costly as well as being fundamentally unnecessary. As long as PLP was going to continue to advocate communism openly, it was argued, then it was pointless to try to maintain a separate organization into which non-communists could "slowly and gradually" be won to the party's ideas. Lastly, as a practical matter, InCAR was simply not getting enough recruits to remain valuable to PL as a separate entity.
The decision to disband InCAR gave an extra boost to a renewed PL P focus on "basebuilding" in the working class, a theory that rests heavily upon what InCAR was designed to do—win the masses gradually and genuinely to a fully communist world outlook. The difference, PLP now argues, is that the slow and gradual process is now being conducted directly into a communist party, rather than first to anti-racism, and then to communism, as it had been previously thought was necessary to do.
PLP today holds to a fierce rejection of the Maoist doctrine of mass line that calls for a more liberal line when working with the masses versus a fully communist-ideology party line to be used within the ideology and functioning of the actual Party. Its rejection of that principle in the mid-1990s as essentially dishonest (it today calls for "one line" across all its political functioning) made the disbanding of InCAR all the more likely.
References
Sociobiology
Anti-racist organizations in the United States
Progressive Labor Party (United States)
Organizations established in 1973
Organizations disestablished in 1996
1973 establishments in the United States
1996 disestablishments in the United States | International Committee Against Racism | Biology | 1,119 |
2,951,410 | https://en.wikipedia.org/wiki/Notarikon | Notarikon () is a Talmudic method of interpreting Biblical words as acronyms. The same term may also be used for a Kabbalistic method of using the acronym of a Biblical verse as a name for God. Another variation uses the first and last letters, or the two middle letters of a word, to form another word. The word "notarikon" is borrowed from the Greek language (νοταρικόν), and was derived from the Latin word "notarius" meaning "shorthand writer."
Notarikon is one of the three methods used by the Kabbalists (the other two are gematria and temurah) to rearrange words and sentences. These methods were used to derive the esoteric substratum and deeper spiritual meaning of the words in the Bible. Notarikon was also used in alchemy.
Usage in the Talmud
Until the end of the Talmudic period, notarikon is understood in Judaism as a method of Scripture interpretation by which the letters of individual words in the Bible text indicate the first letters of independent words.
Usage in Kabbalah
A common usage of notarikon in the practice of Kabbalah, is to form sacred names of God derived from religious or biblical verses. AGLA, an acronym for Atah Gibor Le-olam Adonai, translated, "You, O Lord, are mighty forever," is one of the most famous examples of notarikon. Dozens of examples are found in the Berit Menuchah, as is referenced in the following passage:
The Sefer Gematriot of Judah ben Samuel of Regensburg is another book where many examples of notarikon for use on talismans are given from Biblical verses.
See also
AGLA, notarikon for Atah Gibor Le-olam Adonai
Bible code, a purported set of secret messages encoded within the Torah.
Biblical and Talmudic units of measurement
Chol HaMoed, the intermediate days during Passover and Sukkot.
Chronology of the Bible
Counting of the Omer
Gematria, Jewish system of assigning numerical value to a word or phrase.
Hebrew acronyms
Hebrew calendar
Hebrew numerals
Jewish and Israeli holidays 2000–2050
Lag BaOmer, 33rd day of counting the Omer.
Sephirot, the 10 attributes/emanations found in Kabbalah.
Significance of numbers in Judaism
Weekly Torah portion, division of the Torah into 54 portions.
References
Alchemical processes
Hebrew words and phrases
History of cryptography
Kabbalistic words and phrases
Greek words and phrases
Language and mysticism | Notarikon | Chemistry | 536 |
23,814,036 | https://en.wikipedia.org/wiki/Batrachology | Batrachology is the branch of zoology concerned with the study of amphibians including frogs, salamanders, and caecilians. It is a sub-discipline of herpetology, which also includes non-avian reptiles (snakes, lizards, turtles, crocodilians, and the tuatara). Batrachologists may study the evolution, ecology, ethology, or anatomy of amphibians.
Amphibians are cold blooded vertebrates largely found in damp habitats although many species have special behavioural adaptations that allow them to live in deserts, trees, underground and in regions with wide seasonal variations in temperature. There are over 8700 species of amphibians.
Notable batrachologists
Jean Marius René Guibé
Gabriel Bibron
Oskar Boettger
George Albert Boulenger
Edward Drinker Cope
François Marie Daudin
Franz Werner
Leszek Berger
References
Herpetology
Subfields of zoology | Batrachology | Biology | 193 |
27,408,508 | https://en.wikipedia.org/wiki/Quantum%20process | In quantum mechanics, a quantum process is a somewhat ambiguous term which usually refers to the time evolution of an (open) quantum system. Under very general assumptions, a quantum process is described by the quantum operation formalism (also known as a quantum dynamical map), which is a linear, trace-preserving, and completely positive map from the set of density matrices to itself.
For instance, in quantum process tomography, the unknown quantum process is assumed to be a quantum operation.
However, not all quantum processes can be captured within the quantum operation formalism; in principle, the density matrix of a quantum system can undergo completely arbitrary time evolution.
References
Quantum mechanics | Quantum process | Physics | 135 |
1,880,953 | https://en.wikipedia.org/wiki/Asynchronous%20I/O | In computer science, asynchronous I/O (also non-sequential I/O) is a form of input/output processing that permits other processing to continue before the I/O operation has finished. A name used for asynchronous I/O in the Windows API is overlapped I/O.
Input and output (I/O) operations on a computer can be extremely slow compared to the processing of data. An I/O device can incorporate mechanical devices that must physically move, such as a hard drive seeking a track to read or write; this is often orders of magnitude slower than the switching of electric current. For example, during a disk operation that takes ten milliseconds to perform, a processor that is clocked at one gigahertz could have performed ten million instruction-processing cycles.
A simple approach to I/O would be to start the access and then wait for it to complete. But such an approach, called synchronous I/O or blocking I/O, would block the progress of a program while the communication is in progress, leaving system resources idle. When a program makes many I/O operations (such as a program mainly or largely dependent on user input), this means that the processor can spend almost all of its time idle waiting for I/O operations to complete.
Alternatively, it is possible to start the communication and then perform processing that does not require that the I/O be completed. This approach is called asynchronous input/output. Any task that depends on the I/O having completed (this includes both using the input values and critical operations that claim to assure that a write operation has been completed) still needs to wait for the I/O operation to complete, and thus is still blocked, but other processing that does not have a dependency on the I/O operation can continue.
Many operating system functions exist to implement asynchronous I/O at many levels. In fact, one of the main functions of all but the most rudimentary of operating systems is to perform at least some form of basic asynchronous I/O, though this may not be particularly apparent to the user or the programmer. In the simplest software solution, the hardware device status is polled at intervals to detect whether the device is ready for its next operation. (For example, the CP/M operating system was built this way. Its system call semantics did not require any more elaborate I/O structure than this, though most implementations were more complex, and thereby more efficient.) Direct memory access (DMA) can greatly increase the efficiency of a polling-based system, and hardware interrupts can eliminate the need for polling entirely. Multitasking operating systems can exploit the functionality provided by hardware interrupts, whilst hiding the complexity of interrupt handling from the user. Spooling was one of the first forms of multitasking designed to exploit asynchronous I/O. Finally, multithreading and explicit asynchronous I/O APIs within user processes can exploit asynchronous I/O further, at the cost of extra software complexity.
Asynchronous I/O is used to improve energy efficiency, and in some cases, throughput. However, it can have negative effects on latency and throughput in some cases.
Forms
Forms of I/O and examples of POSIX functions:
All forms of asynchronous I/O open applications up to potential resource conflicts and associated failure. Careful programming (often using mutual exclusion, semaphores, etc.) is required to prevent this.
When exposing asynchronous I/O to applications there are a few broad classes of implementation. The form of the API provided to the application does not necessarily correspond with the mechanism actually provided by the operating system; emulations are possible. Furthermore, more than one method may be used by a single application, depending on its needs and the desires of its programmer(s). Many operating systems provide more than one of these mechanisms, it is possible that some may provide all of them.
Process
Available in early Unix. In a multitasking operating system, processing can be distributed across different processes, which run independently, have their own memory, and process their own I/O flows; these flows are typically connected in pipelines. Processes are fairly expensive to create and maintain, so this solution only works well if the set of processes is small and relatively stable. It also assumes that the individual processes can operate independently, apart from processing each other's I/O; if they need to communicate in other ways, coordinating them can become difficult.
An extension of this approach is dataflow programming, which allows more complicated networks than just the chains that pipes support.
Polling
Variations:
Error if it cannot be done yet (reissue later)
Report when it can be done without blocking (then issue it)
Polling provides non-blocking synchronous API which may be used to implement some asynchronous API. Available in traditional Unix and Windows. Its major problem is that it can waste CPU time polling repeatedly when there is nothing else for the issuing process to do, reducing the time available for other processes. Also, because a polling application is essentially single-threaded it may be unable to fully exploit I/O parallelism that the hardware is capable of.
Select(/poll) loops
Available in BSD Unix, and almost anything else with a TCP/IP protocol stack that either utilizes or is modeled after the BSD implementation. A variation on the theme of polling, a select loop uses the select system call to sleep until a condition occurs on a file descriptor (e.g., when data is available for reading), a timeout occurs, or a signal is received (e.g., when a child process dies). By examining the return parameters of the select call, the loop finds out which file descriptor has changed and executes the appropriate code. Often, for ease of use, the select loop is implemented as an event loop, perhaps using callback functions; the situation lends itself particularly well to event-driven programming.
While this method is reliable and relatively efficient, it depends heavily on the Unix paradigm that "everything is a file"; any blocking I/O that does not involve a file descriptor will block the process. The select loop also relies on being able to involve all I/O in the central select call; libraries that conduct their own I/O are particularly problematic in this respect. An additional potential problem is that the select and the I/O operations are still sufficiently decoupled that select's result may effectively be a lie: if two processes are reading from a single file descriptor (arguably bad design) the select may indicate the availability of read data that has disappeared by the time that the read is issued, thus resulting in blocking; if two processes are writing to a single file descriptor (not that uncommon) the select may indicate immediate writability yet the write may still block, because a buffer has been filled by the other process in the interim, or due to the write being too large for the available buffer or in other ways unsuitable to the recipient.
The select loop does not reach the ultimate system efficiency possible with, say, the completion queues method, because the semantics of the select call, allowing as it does for per-call tuning of the acceptable event set, consumes some amount of time per invocation traversing the selection array. This creates little overhead for user applications that might have open one file descriptor for the windowing system and a few for open files, but becomes more of a problem as the number of potential event sources grows, and can hinder development of many-client server applications, as in the C10k problem; other asynchronous methods may be noticeably more efficient in such cases. Some Unixes provide system-specific calls with better scaling; for example, epoll in Linux (that fills the return selection array with only those event sources on which an event has occurred), kqueue in FreeBSD, and event ports (and /dev/poll) in Solaris.
SVR3 Unix provided the poll system call. Arguably better-named than select, for the purposes of this discussion it is essentially the same thing. SVR4 Unixes (and thus POSIX) offer both calls.
Signals (interrupts)
Available in BSD and POSIX Unix. I/O is issued asynchronously, and when it is completed a signal (interrupt) is generated. As in low-level kernel programming, the facilities available for safe use within the signal handler are limited, and the main flow of the process could have been interrupted at nearly any point, resulting in inconsistent data structures as seen by the signal handler. The signal handler is usually not able to issue further asynchronous I/O by itself.
The signal approach, though relatively simple to implement within the OS, brings to the application program the unwelcome baggage associated with writing an operating system's kernel interrupt system. Its worst characteristic is that every blocking (synchronous) system call is potentially interruptible; the programmer must usually incorporate retry code at each call.
Callback functions
Available in the classic Mac OS, VMS and Windows. Bears many of the characteristics of the signal method as it is fundamentally the same thing, though rarely recognized as such. The difference is that each I/O request usually can have its own completion function, whereas the signal system has a single callback.
On the other hand, a potential problem of using callbacks is that stack depth can grow unmanageably, as an extremely common thing to do when one I/O is finished is to schedule another. If this should be satisfied immediately, the first callback is not 'unwound' off the stack before the next one is invoked. Systems to prevent this (like 'mid-ground' scheduling of new work) add complexity and reduce performance. In practice, however, this is generally not a problem because the new I/O will itself usually return as soon as the new I/O is started allowing the stack to be 'unwound'. The problem can also be prevented by avoiding any further callbacks, by means of a queue, until the first callback returns.
Light-weight processes or threads
Light-weight processes (LWPs) or threads are available in most modern operating systems. Like the process method, but with lower overhead and without the data isolation that hampers coordination of the flows. Each LWP or thread itself uses traditional blocking synchronous I/O, which simplifies programming logic; this is a common paradigm used in many programming languages including Java and Rust. Multithreading needs to use kernel-provided synchronization mechanisms and thread-safe libraries. This method is not most suitable for extremely large-scale applications like web servers due to the large numbers of threads needed.
This approach is also used in the Erlang programming language runtime system. The Erlang virtual machine uses asynchronous I/O using a small pool of only a few threads or sometimes just one process, to handle I/O from up to millions of Erlang processes. I/O handling in each process is written mostly using blocking synchronous I/O. This way high performance of asynchronous I/O is merged with simplicity of normal I/O (c.f. the Actor model). Many I/O problems in Erlang are mapped to message passing, which can be easily processed using built-in selective receive.
Fibers / Coroutines can be viewed as a similarly lightweight approach to do asynchronous I/O outside of the Erlang runtime system, although they do not provide exactly the same guarantees as Erlang processes.
Completion queues/ports
Available in Microsoft Windows, Solaris, AmigaOS, DNIX and Linux (using io_uring, available on 5.1 and above). I/O requests are issued asynchronously, but notifications of completion are provided via a synchronizing queue mechanism in the order they are completed. Usually associated with a state-machine structuring of the main process (event-driven programming), which can bear little resemblance to a process that does not use asynchronous I/O or that uses one of the other forms, hampering code reuse. Does not require additional special synchronization mechanisms or thread-safe libraries, nor are the textual (code) and time (event) flows separated.
Event flags
Available in VMS and AmigaOS (often used in conjunction with a completion port). Bears many of the characteristics of the completion queue method, as it is essentially a completion queue of depth one. To simulate the effect of queue 'depth', an additional event flag is required for each potential unprocessed (but completed) event, or event information can be lost. Waiting for the next available event in such a clump requires synchronizing mechanisms that may not scale well to larger numbers of potentially parallel events.
Channel I/O
Available in mainframes by IBM, Groupe Bull, and Unisys. Channel I/O is designed to maximize CPU utilization and throughput by offloading most I/O onto a coprocessor. The coprocessor has onboard DMA, handles device interrupts, is controlled by the main CPU, and only interrupts the main CPU when it's truly necessary. This architecture also supports so-called channel programs that run on the channel processor to do heavy lifting for I/O activities and protocols.
Registered I/O
Available in Windows Server 2012 and Windows 8. Optimized for applications that process large numbers of small messages to achieve higher I/O operations per second with reduced jitter and latency.
Implementation
The vast majority of general-purpose computing hardware relies entirely upon two methods of implementing asynchronous I/O: polling and interrupts. Usually both methods are used together, the balance depends heavily upon the design of the hardware and its required performance characteristics. (DMA is not itself another independent method, it is merely a means by which more work can be done per poll or interrupt.)
Pure polling systems are entirely possible, small microcontrollers (such as systems using the PIC) are often built this way. CP/M systems could also be built this way (though rarely were), with or without DMA. Also, when the utmost performance is necessary for only a few tasks, at the expense of any other potential tasks, polling may also be appropriate as the overhead of taking interrupts may be unwelcome. (Servicing an interrupt requires time [and space] to save at least part of the processor state, along with the time required to resume the interrupted task.)
Most general-purpose computing systems rely heavily upon interrupts. A pure interrupt system may be possible, though usually some component of polling is also required, as it is very common for multiple potential sources of interrupts to share a common interrupt signal line, in which case polling is used within the device driver to resolve the actual source. (This resolution time also contributes to an interrupt system's performance penalty. Over the years a great deal of work has been done to try to minimize the overhead associated with servicing an interrupt. Current interrupt systems are rather lackadaisical when compared to some highly tuned earlier ones, but the general increase in hardware performance has greatly mitigated this.)
Hybrid approaches are also possible, wherein an interrupt can trigger the beginning of some burst of asynchronous I/O, and polling is used within the burst itself. This technique is common in high-speed device drivers, such as network or disk, where the time lost in returning to the pre-interrupt task is greater than the time until the next required servicing. (Common I/O hardware in use these days relies heavily upon DMA and large data buffers to make up for a relatively poorly-performing interrupt system. These characteristically use polling inside the driver loops, and can exhibit tremendous throughput. Ideally the per-datum polls are always successful, or at most repeated a small number of times.)
At one time this sort of hybrid approach was common in disk and network drivers where there was not DMA or significant buffering available. Because the desired transfer speeds were faster even than could tolerate the minimum four-operation per-datum loop (bit-test, conditional-branch-to-self, fetch, and store), the hardware would often be built with automatic wait state generation on the I/O device, pushing the data ready poll out of software and onto the processor's fetch or store hardware and reducing the programmed loop to two operations. (In effect using the processor itself as a DMA engine.) The 6502 processor offered an unusual means to provide a three-element per-datum loop, as it had a hardware pin that, when asserted, would cause the processor's Overflow bit to be set directly. (Obviously one would have to take great care in the hardware design to avoid overriding the Overflow bit outside of the device driver!)
Synthesis
Using only these two tools (polling, and interrupts), all the other forms of asynchronous I/O discussed above may be (and in fact, are) synthesized.
In an environment such as a Java virtual machine (JVM), asynchronous I/O can be synthesized even though the environment the JVM is running in may not offer it at all. This is due to the interpreted nature of the JVM. The JVM may poll (or take an interrupt) periodically to institute an internal flow of control change, effecting the appearance of multiple simultaneous processes, at least some of which presumably exist in order to perform asynchronous I/O. (Of course, at the microscopic level the parallelism may be rather coarse and exhibit some non-ideal characteristics, but on the surface it will appear to be as desired.)
That, in fact, is the problem with using polling in any form to synthesize a different form of asynchronous I/O. Every CPU cycle that is a poll is wasted, and lost to overhead rather than accomplishing a desired task. Every CPU cycle that is not a poll represents an increase in latency of reaction to pending I/O. Striking an acceptable balance between these two opposing forces is difficult. (This is why hardware interrupt systems were invented in the first place.)
The trick to maximize efficiency is to minimize the amount of work that has to be done upon reception of an interrupt in order to awaken the appropriate application. Secondarily (but perhaps no less important) is the method the application itself uses to determine what it needs to do.
Particularly problematic (for application efficiency) are the exposed polling methods, including the select/poll mechanisms. Though the underlying I/O events they are interested in are in all likelihood interrupt-driven, the interaction to this mechanism is polled and can consume a large amount of time in the poll. This is particularly true of the potentially large-scale polling possible through select (and poll). Interrupts map very well to Signals, Callback functions, Completion Queues, and Event flags, such systems can be very efficient.
Examples
The following examples show three approaches to reading I/O. The objects and functions are abstract.
1. Blocking, synchronous:
device = IO.open()
data = device.read() # thread will be blocked until there is data in the device
print(data)
2. Blocking and non-blocking, synchronous: (here IO.poll() blocks for up to 5 seconds, but device.read() doesn't)
device = IO.open()
ready = False
while not ready:
print("There is no data to read!")
ready = IO.poll(device, IO.INPUT, 5) # returns control if 5 seconds have elapsed or there is data to read (INPUT)
data = device.read()
print(data)
3. Non-blocking, asynchronous:
ios = IO.IOService()
device = IO.open(ios)
def inputHandler(data, err):
"Input data handler"
if not err:
print(data)
device.readSome(inputHandler)
ios.loop() # wait till all operations have been completed and call all appropriate handlers
Here is the same example with Async/await:
ios = IO.IOService()
device = IO.open(ios)
async def task():
try:
data = await device.readSome()
print(data)
except Exception:
pass
ios.addTask(task)
ios.loop() # wait till all operations have been completed and call all appropriate handlers
Here is the example with Reactor pattern:
device = IO.open()
reactor = IO.Reactor()
def inputHandler(data):
"Input data handler"
print(data)
reactor.stop()
reactor.addHandler(inputHandler, device, IO.INPUT)
reactor.run() # run reactor, which handles events and calls appropriate handlers
See also
Input/output completion port (IOCP)
C10k problem
References
External links
The C10K Problem; a survey of asynchronous I/O methods with emphasis on scaling – by Dan Kegel
Article "Boost application performance using asynchronous I/O" by M. Tim Jones
Article "Lazy Asynchronous I/O For Event-Driven Servers" by Willy Zwaenepoel, Khaled Elmeleegy, Anupam Chanda and Alan L. Cox
Perform I/O Operations in Parallel
Description from POSIX standard
Inside I/O Completion Ports by Mark Russinovich
Description from .NET Framework Developer's Guide
Asynchronous I/O and The Asynchronous Disk I/O Explorer
IO::AIO is a Perl module offering an asynchronous interface for most I/O operations
ACE Proactor
Concurrency control
Events (computing)
Input/output | Asynchronous I/O | Technology | 4,608 |
5,848,556 | https://en.wikipedia.org/wiki/Inocybe | Inocybe is a large genus of mushroom-forming fungi with over 1400 species, including all forms and varieties. Members of Inocybe are mycorrhizal, and some evidence shows that the high degree of speciation in the genus is due to adaptation to different trees and perhaps even local environments.
Etymology
The name Inocybe means "fibrous hat". It is taken from the Greek words (in the genitive , meaning "muscle, nerve, fiber, strength, vigor") and ("head").
History
The genus was first described as Agaricus tribe Inocybe by Swedish scholar Elias Magnus Fries in volume 1 of his work, Systema mycologicum (1821), and verified in the volume 2 of his book Monographia Hymenomycetum Sueciae in 1863. All other renaming attempts are accepted synonymous.
Description
Typical mushrooms of the genus have various shades of brown, although some lilac or purplish species exist. Caps are small and conical, though flattening somewhat in age, generally with a pronounced central umbo. The cap often appears fibrous, giving the genus its common name of "fiber caps". Many species have a distinctive odor, various described as musty or spermatic.
Description valid for most species:
Pileus: small to medium size, thin, fleshy, initially narrow conical or bell-shaped, or with a prominent or flattened umbo in the center. It is not hygrophanous and has a dry appearance. The pileus margin often shows at first a pale curtain that disappears quickly, and in old age it often presents short radial cracks. The cuticle is finely silky and sometimes sprinkled with remnants of the partial veil, further developing radial fibers. There are also species with a woolly surface (woolly in mycological sense). Coloring is at first all white to gray-whitish varieties. Some retain color, others change, varying between ocher-yellowish and brown, various shapes, even lilac-like to purple.
Lamellae: are dense, thick and crowded, with short intermediate sinus at the edge and only weakly attached to the stipe, almost free. Coloring is mainly white at the beginning, which becomes mature turns to gray-brown, ocher-brown or gray-olive. The edges are whitish.
Spores: they are brownish, tiny, normally oval to slightly ellipsoidal, often elongated in the form of almonds or beans (Clypeus tuberculous or star-shaped subgenus), smooth, never verrucous and germ-free. Basidia are tetrasporic. Cystidia with or without crystalline crystals, spindle-shaped, convex in the middle and with a sharp point at the tip.
Stipe: it is thin, fibrous, cylindrical, more or less thickened and felt-white at the base, hollow inside. The surface is whitish, smooth, glossy, and often silky and slightly furfuraceous towards the apex of the stipe. It usually does not have a ring.
Context: white to slightly yellowish, oxidized or not to reddish when cutting, usually having a faint smell of green corn, chlorine or sperm. Commonly the flesh contains muscarine.
Classification
Originally placed in the family Cortinariaceae (later shown to be polyphyletic), phylogenetic analyses suggests that the genus is better placed as the type genus of the family Inocybaceae.
Neurotoxicity
Many Inocybe species contain large doses of muscarine, and no easy method of distinguishing them from potentially edible species exists. In fact, Inocybe is the most commonly encountered mushroom genus for which microscopic characteristics are the only means of certain identification to the species level. While the vast majority of Inocybes are neurotoxic, several rare species of Inocybe are hallucinogenic, having been found to contain indole alkaloids.
Sections or subgenera
Source:
Two supersections are informally recognized: Cortinate supersection: The stipe is only pruinose at the apex or the upper half. The stipe base is (generally) not bulbous and a remnant of a cortina is present in the margin of the young cap. Marginate supersection: The stipe are entirely pruinose and has a bulbose base as general.
Several genera are recognized within the family Inocybaceae:Inocybe
This subgenus has pleurocystidia, usually thick-walled and in the apex has crystals. The basidiospores are smooth or angular-nodulose. The basidia is not necropigmented (basidia that become ochraceous and collapse). The hilar appendice is conspicuous. This subgenera is cosmopolitan and frequent in temperate ecosystems.
Auritella
This subgenus has no pleurocystidia and has necropigmented basidia. The spores are smooth and the hilar appendix is inconspicuous. Large cheilocystidia (>50 um). This is known from tropical Africa, Tropical, India and temperate Australia.
Inosperma
The fruiting bodies of this subgenus usually have a distinct odor (fruity, honey-like, fishy). The pileus is radially rimose ("Rimosae") or can be squamulose to squarrose ("Cervicolores"). The lamella has no pleurocystidia, but has cheilocystidia. Basidia necropigmented or not. The spores are smooth. In temperate areas. Wide distribution.
Mallocybe
The cap is usually woolly-squamulose, the cap surface is conspicuously darkening with alkali. The lamella broadly adnate to subdecurrent. The stipe is shorter and has not pleurocystidia. The basidia are necropigmented and there are also cheilocystidia as terminal elements. Spores smooth. Wide distribution
Nothocybe
The lamellae have no pleurocystidia but there are cheilocystidia. Spores smooth. Known from tropical India.
Pseudosperma
Fruitbodies have indistinct, spermatic or green corn odor. The pileus is radially rimose or rimulose, never squarrulose and rarely squamulose. Pleurocystidia are absent and cheilocystida are present. Spores smooth. Wide distribution.
Tubariomyces
Small fruiting bodies with tubarioid or omphalinoid habit. Decurrent lamellae and cheilocystiidia present. Spores smooth. Known from mediterranean and tropical Africa.
Sections based in morphology
The genus Inocybe is very species-rich. The genus is divided according to Bon (2005) into three subgenera with sections:
Subgenus: Inosperma (now a separate genus) - without crystal-bearing cystidia
Section: Depauperatae: wool-peeling surface
Inocybe dulcamara
Section: Cervicolores: cap with wool-peeling cuticle, strong aroma (sperm like)
Inocybe bongardii
Section: Rimosae: cap always radially fibrous and cracked
Inocybe rimosa
Inocybe erubescens
Subgenus: Inocibium - with thick-walled, crystal-bearing pleurocystidia.
Section: Lactiferae: red or even greenish, with an extreme odor
Inocybe piriodora
Inocybe pudica
Section: Lilacinae: cap lilac, wool-peel surface, and scaly. Common.
Inocybe oscura
Inocybe hystrix
Inocybe griseolilacin
Section: Lacerae: non- rimose stipe, no liliac shades.
Inocybe lacera
Section: Tardae: stipe only bumpy at the top
Inocybe geophylla
Inocybe flocculosa
Inocybe virgatula
Section: Splendentes: stipe rimed completely or two-thirds.
Inocybe hirtella
Subgenus: Clypeus - spores tuberculate or star-shaped
Section: Cortinatae: stipe thin or bumped to the top
Inocybe lanuginosa
Section: Petiginosae :full bumpy stipe without basl bulb
Inocybe fibrosa
Section: Marginatae: stipe pruinose with basal bulb. Crimping
Inocybe asterospora
Species
It is estimated that there are ca. 1050 species within Inocybe. Representatives of the genus include:
Inocybe aeruginascens (psychoactive)
Inocybe coelestium (psychoactive)
Inocybe corydalina var. corydalina Quél. (psychoactive)
Inocybe corydalina var. erinaceomorpha (psychoactive)
Inocybe geophylla (toxic)
Inocybe haemacta (psychoactive)
Inocybe hystrix
Inocybe lacera
Inocybe tricolor (psychoactive)
Images of selected species
References
Further reading
Stuntz, D. E. (1978). Interim skeleton key to some common species of Inocybe in the Pacific Northwest. Notes and species descriptions by Gibson, I. (2004).
External links
Inocybe Photos (www.pilzepilze.de)
http://www.inocybe.org/
Poisonous fungi
Agaricales genera
Taxa named by Elias Magnus Fries
Neurotoxins | Inocybe | Chemistry,Environmental_science | 2,025 |
28,996,190 | https://en.wikipedia.org/wiki/Tripropylene | Tripropylene, also known as propylene trimer, is usually sold as a mixture of structural isomers of nonene. This mixture is obtained by oligomerization of propene:
3 C3H6 → C9H18
In this process, two double bonds are lost and one is retained as illustrated by the isomer shown in the figure. The reaction is catalyzed by acids, such as polyphosphoric acid. A variety of catalysts have been explored. The reaction proceeds via the formation of a carbocation ((CH3)2CH+), which attacks another propylene unit, generating a new carbocation, etc. This kind of process affords mixtures (C3H6)n.
Like other alkenes, propylene trimer is used as an alkylating agent. A number of surfactants and lubricants are produced by alkylation of aromatic substrates.
See also
1-Nonene - the linear analogue
References
Alkenes
Trimers (chemistry) | Tripropylene | Chemistry | 218 |
13,935,428 | https://en.wikipedia.org/wiki/Docosanoid | In biochemistry, docosanoids are signaling molecules made by the metabolism of twenty-two-carbon fatty acids (EFAs), especially the omega-3 fatty acid, docosahexaenoic acid (DHA) (i.e. 4Z,7Z,10Z,13Z,16Z,19Z-docosahexaenoic acid) by lipoxygenase, cyclooxygenase, and cytochrome P450 enzymes. Other docosanoids are metabolites of n-3 docosapentaenoic acid (DPA) (i.e. 7Z,10Z,13Z,16Z,19Z-docosapentaenoic acid, or clupanodonic acid), n-6 DPA (i.e. 4Z,7Z,10Z,13Z,16Z-docosapentaenoic acid, or osbond acid), and docosatetraenoic acid (i.e. 7Z,10Z,13Z,16Z-docosatetraenoic acid, DTA, or adrenic acid). Prominent docosanoid metabolites of DPA and n-3 DHA are members of the specialized pro-resolving mediators class of polyunsaturated fatty acid metabolites that possess potent anti-inflammation, tissue healing, and other activities.
Prominent docosanoids
Specialized proresolving mediator docosanoids
Potently bioactive agents of the specialized proresolving mediator class include:
DHA-derived resolvins (Rvs) of the D series: RvD1, RvD2, RvD3, RvD4, RvD5, RvD6, AT-RvD1, AT-RvD2, AT-RvD3, AT-RvD4, AT-RvD5, and AT-RvD6.
n-3 DPA-derived resolvins of the D series (RvD1n-3, RvD2n-3, and RvD5n-3) and the T series (RvT1, RvT2, RvT3, and RvT4).
DHA-derived neuroprotectins, also termed protectins: PD1, PDX, 17-epi-PD1, and 10-epi-PD1.
n-3 DPA derived protectins: PD1n-3 and PD2n-3.
DHA-derived maresins: MaR1, MaR2, 7-epi-Mar1, Mar-L1, and Mar-L2.
n-3 DPA-derived maresins: Mar1n-3, Mar2n-3, and Mar3n-3.
These DHA metabolites possess anti-inflammation and tissue-protection activities in animal models of inflammatory diseases; they are proposed to inhibit innate immune responses and thereby to protect from and to resolve a wide range of inflammatory responses in animals and humans. These metabolites are also proposed to contribute to the anti-inflammatory and other beneficial effects of dietary omega-3 fatty acids by being metabolized to them.
Neurofuran docosanoids
DHA can be converted non-enzymatically by free radical-mediated peroxidation to 8 different neurofuran regioisomers termed neuroprostanes and neurofuranes including 4-, 7-, 10-, 11-, 13-, 14-, 17-, and 20-series neurofurans/neuroporstanes for a total of 128 different racemic compounds. The most studied DHA-derived of these products are members of the 4-series, neurofuran 4-Fαneuroprostane and 4(RS)-ST-Δ6-8-neurofurane. These metabolites have been used mainly as biomarkers of oxidative stress that are formed in nerve tissues of the central nervous system.
Hydroxy-docosanoids
Cells metabolize DHA to 17S-hydroperoxy-4Z,7Z,10Z,13Z,15E,19Z-docosahexaenoic acid (17-HpDHA) and then rapidly reduce this hydroperoxide to 17S-hydroxy-4Z,7Z,10Z,13Z,15E,19Z-docosahexaenoic acid (17-HDHA) and similarly metabolize DHA to 13S-hydroperoxy-4Z,7Z,10Z,14Z,16Z,19Z-docosahexaenoic acid (13-HpDHA) and then to 13S-hydroxy-4Z,7Z,10Z,14Z,16Z,19Z-docosahexaenoic acid (13-HDHA). 17-HDHA exhibits potent in vitro as well as in vivo (animal model) anti-inflammatory activity while 17-HpDHA and to a lesser extent 17-HDHA inhibit the growth of cultured human breast cancer cells. Other SPM docosanoids, e.g. RvD1 and RvD2, have anti-growth effects against cancer cells in animal models.
Oxo-docosanoids
Cells can metabolize DHA to products that possess an oxo (i.e. ketone) residue. These products include 13-oxo-DHA (termed EFOXD6) and 17-oxo-DHA (termed 18-EFOXD6). Both oxo metabolites possess anti-inflammatory activity as assesses in in vitro systems (see ).
DTA-derived docosanoids
Cyclooxygenase and cytochrome P450 oxidase act upon docosatetraenoic acid to produce dihomoprostaglandins, dihomo-epoxyeicosatrienoic acids, and dihomo-EETs.
References
Cell biology
Cell signaling
Cell communication
Biomolecules
Immunology
Fatty acids | Docosanoid | Chemistry,Biology | 1,285 |
13,981,709 | https://en.wikipedia.org/wiki/TBX19 | T-box transcription factor TBX19 is a protein that in humans is encoded by the TBX19 gene.
This gene is a member of a phylogenetically conserved family of genes that share a common DNA-binding domain, the T-box. T-box genes encode transcription factors involved in the regulation of developmental processes.
This gene is the human ortholog of mouse Tbx19/Tpit gene. Studies in mouse show that Tpit protein is present only in the two pituitary pro-opiomelanocortin (POMC)-expressing lineages, the corticotrophs and melanotrophs.
The Tpit gene is responsible for a neonatal form of acth deficiency and hypocortisolism.
Mutations in the human ortholog were found in patients with isolated deficiency of pituitary POMC-derived ACTH, suggesting an essential role for this gene in differentiation of the pituitary POMC lineage.
See also
Adrenocorticotropic hormone deficiency
References
Further reading
External links
Transcription factors | TBX19 | Chemistry,Biology | 218 |
60,412,718 | https://en.wikipedia.org/wiki/Allan%20Hills%2077005 | Allan Hills 77005 (also known as Allan Hills A77005, ALHA77005, ALH77005 and ALH-77005) is a Martian meteorite that was found in the Allan Hills of Antarctica in 1977 by a Japanese National Institute of Polar Research mission team and ANSMET. Like other members of the group of SNCs (shergottite, nakhlite, chassignite), ALH-77005 is thought to be from Mars.
Description
On discovery, the mass of ALH-77005 was . Initial geological examination determined that the meteorite was composed of ~55% olivine, ~35% pyroxene, ~8% maskelynite and ~2% opaques.
In March 2019, researchers reported the possibility of biosignatures in this Martian meteorite based on its microtexture and morphology as detected with optical microscopy and FTIR-ATR microscopy, and on the detection of mineralized organic compounds, suggesting that microbial life could have existed on the planet Mars. More broadly, and as a result of their studies, the researchers suggest Solar System materials should be carefully studied to determine whether there may be signs of microbial forms within other space rocks as well.
See also
Allan Hills 84001
Glossary of meteoritics
History of Mars observation
Life on Mars
List of Martian meteorites on Earth
List of meteorites on Mars
Nakhla meteorite
Mars sample return mission
Panspermia
Shergotty meteorite
Water on Mars
References
Further reading
External links
Meteoritical Society
The British and Irish Meteorite Society
The Natural History Museum's meteorite catalogue database
Astrobiology
Martian meteorites
Meteorites found in Antarctica | Allan Hills 77005 | Astronomy,Biology | 353 |
69,392,090 | https://en.wikipedia.org/wiki/Transition%20metal%20nitrate%20complex | A transition metal nitrate complex is a coordination compound containing one or more nitrate ligands. Such complexes are common starting reagents for the preparation of other compounds.
Ligand properties
Being the conjugate base of a strong acid (nitric acid, pKa = -1.4), nitrate has modest Lewis basicity. Two coordination modes are common: unidentate and bidentate. Often, bidentate nitrate, denoted κ2-NO3, is bound unsymmetrically in the sense that one M-O distance is clearly bonding and the other is more weakly interacting. The MO-N distances for the coordinated oxygen are longer by about 10 picometers longer than the N-Oterminal bonds. This observation suggests that the terminal N-O bonds have double bond character. Nitrate is isostructural with but less basic than carbonate. Both exhibit comparable coordination geometries. The nitrogen center of nitrate does not form bonds to metals.
Coordination complexes
With three terminal oxide groups, nitrate can in principle bind metals through many geometries. Even though the ligand is written as MNO3, the oxygen atoms are invariably coordinated. Thus, monodentate nitrate is illustrated by [Co(NH3)5NO3]2+, which could also be written as [Co(NH3)5ONO2]2+. Homoleptic metal nitrate complexes generally have O,O'-bidentate nitrate ligands.
Hydrates
Typical metal nitrates are hydrated. Some of these salts crystallize with one or more nitrate ligands, but most are assumed to dissolve in water to give aquo complexes, often of the stoichiometry [M(H2O)6]n+.
Cr(NO3)3(H2O)6
Mn(NO3)2(H2O)4
Fe(NO3)3(H2O)9
Co(NO3)2(H2O)2
Ni(NO3)2(H2O)4
Pd(NO3)2(H2O)2
Cu(NO3)2(H2O)x
Zn(NO3)2(H2O)4
Hg2(NO3)2(H2O)2
Synthesis
Metal nitrate complexes are often prepared by treating metal oxides or metal carbonates with nitric acid. The main complication with dissolving metals in nitric acid arises from redox reactions, which can afford either nitric oxide or nitrogen dioxide.
Anhydrous nitrates can be prepared by the oxidation of metals with dinitrogen tetroxide (often as a mixture with nitrogen dioxide, with which it interconverts). N2O4 undergoes molecular autoionization to give [NO+] [NO3−], with the former nitrosonium ion being a strong oxidant. The method is illustrated by the route to β-Cu(NO3)2:
Cu + 2N2O4 → Cu(NO3)2 + 2NO
Many metals, metal halides, and metal carbonyls undergo similar reactions, but the product formulas can be deceptive. For example from chromium one obtains Cr(NO3)3(N2O4)2, which was shown to be the salt (NO+)2[Cr(NO3)5]2-. Nitrogen oxides readily interconvert between various forms, some of which may act as completing ligands. The redox reaction of nitrosonium and the metal can give rise to nitrogen oxide which forms strong metal nitrosyl complexes; nitronium ions (NO2+) are similarly observed.
In some cases, nitrate complexes are produced from the reaction of nitrogen dioxide with a metal dioxygen complex:
(PPh3 = triphenylphosphine)
Reactions
Given nitrate's low basicity, the tendency of metal nitrate complexes toward hydrolysis is expected. Thus copper(II) nitrate readily dissociates in aqueous solution to give the aqua complex:
Cu(NO3)2 + 6 H2O → [Cu(H2O)6](NO3)2
Pyrolysis of metal nitrates yields oxides.
Ni(NO3)2 → NiO + NO2 + 0.5O2
This reaction is used to impregnate oxide supports with nickel oxides.
Nitrate reductase enzymes convert nitrate to nitrite. The mechanism involves the intermediacy of Mo-ONO2 complexes.
References
Nitrates | Transition metal nitrate complex | Chemistry | 942 |
17,131,878 | https://en.wikipedia.org/wiki/Tamer%20Ba%C5%9Far | Mustafa Tamer Başar (born January 19, 1946) is a control and game theorist who is the Swanlund Endowed Chair and Center for Advanced Study Professor of Electrical and Computer Engineering at the University of Illinois at Urbana-Champaign, USA. He is also the Director of the Center for Advanced Study (since 2014).
Education
Tamer Başar received a B.S. in Electrical Engineering from Boğaziçi University (formerly known as Robert College) at Bebek, in Istanbul, Turkey, in 1969, and M.S., M.Phil., and Ph.D. in engineering and applied science from Yale University, in 1970, 1971 and 1972, respectively.
Academic life
He joined the University of Illinois at Urbana–Champaign - Electrical and Computer Engineering Department in 1981. He was the founding president of the International Society of Dynamic Games during 1990–1994, the president of the IEEE Control Systems Society in 2000, and the president of the American Automatic Control Council during 2010–2011. He received the Medal of Science of Turkey in 1993, H.W. Bode Lecture Prize of the IEEE Control Systems Society in 2004, Georgia Quazza Medal of the International Federation of Automatic Control in 2005, the Richard E. Bellman Control Heritage Award in 2006, Isaacs Award of the International Society of Dynamic Games in 2010, and IEEE Control Systems Award in 2014. He was elected as a member of National Academy of Engineering in 2000 in Electronics, Communication & Information Systems Engineering and Industrial, Manufacturing & Operational Systems Engineering for the development of dynamic game theory and application to robust control of systems with uncertainty. He is a Fellow of IEEE, IFAC, and SIAM.
Honorary degrees and chairs
He has been awarded Honorary Doctor of Science degrees and Honorary Professorships from:
Honorary Professorship, Shandong University, Jinan, China, 2019
Honorary Chair Professorship from Tsinghua University, Beijing, China in 2014
Honorary Doctorate (Doctor Honoris Causa) from Boğaziçi University, Istanbul, Turkey in 2012
Honorary Doctorate from the National Academy of Sciences of Azerbaijan in 2011
Honorary Professorship from Northeastern University, Shenyang, China in 2008
Honorary Doctorate (Doctor Honoris Causa) from Doğuş University, Istanbul, Turkey in 2007
Swanlund Endowed Chair Professorship at UIUC in 2007
Research areas
His research interests include optimal, robust, and nonlinear control; large-scale systems; dynamic games; stochastic control; estimation theory; stochastic processes; and mathematical economics.
Awards
AAA&S Member (2023)
IEEE Control Systems Award (2014)
Honorary Chair Professorship from Tsinghua University, Beijing, China (2014)
Honorary Doctorate (Doctor Honoris Causa) from Boğaziçi University, Istanbul (2012)
SIAM Fellow (2012)
Honorary Doctorate from the National Academy of Sciences of Azerbaijan (2011)
Isaacs Award of ISDG (2010, 2014)
Honorary Professorship from Northeastern University, Shenyang, China (2008)
Swanlund Endowed Chair at UIUC (2007)
Honorary Doctorate (Doctor Honoris Causa) from Doğuş University, Istanbul (2007)
Richard E. Bellman Control Heritage Award (2006)
Giorgio Quazza Medal of IFAC (2005)
Outstanding Service Award of IFAC (2005)
IFAC Fellow (2005)
Center for Advanced Study Professorship at UIUC (2005)
Hendrik Wade Bode Lecture Prize of the IEEE Control Systems Society (2004)
Tau Beta Pi Daniel C. Drucker Eminent Faculty Award of the College of Engineering of UIUC (2004)
Elected to the National Academy of Engineering (of the USA) (2000)
IEEE Millennium Medal (2000)
Fredric G. and Elizabeth H. Nearing Distinguished Professorship at UIUC (1998)
Axelby Outstanding Paper Award (1995)
Distinguished Member Award of the IEEE Control Systems Society (1993)
Medal of Science of Turkey (1993)
IEEE Fellow (1983)
See also
List of game theorists
List of members of the National Academy of Engineering (Electronics)
References
1946 births
Living people
Boğaziçi University alumni
Academic staff of Boğaziçi University
Yale School of Engineering & Applied Science alumni
University of Illinois Urbana-Champaign faculty
Members of the United States National Academy of Engineering
Game theorists
Control theorists
Communication theorists
Turkish academics
Turkish scientists
Turkish mathematicians
Turkish electrical engineers
American electrical engineers
American academics of Turkish descent
Fellows of the IEEE
Fellows of the Society for Industrial and Applied Mathematics
Richard E. Bellman Control Heritage Award recipients | Tamer Başar | Mathematics,Engineering | 876 |
72,759,975 | https://en.wikipedia.org/wiki/Limonium%20sinense | Limonium sinense is a species of flowering plant in the sea lavender genus Limonium, family Plumbaginaceae, native to coastal China, Taiwan, the Ryukyu Islands, and Vietnam. It is a perennial reaching , found on sandy, salty shales next to the ocean. There are a large number of cultivars, with a wide variety of flower colors, created for the cut flower industry. Wild individuals have flowers with white sepals and yellow petals.
References
sinense
Halophytes
Garden plants
Flora of Manchuria
Flora of North-Central China
Flora of Southeast China
Flora of Taiwan
Flora of the Ryukyu Islands
Flora of Vietnam
Plants described in 1891 | Limonium sinense | Chemistry | 134 |
68,536,133 | https://en.wikipedia.org/wiki/Salkowski%27s%20test | Salkowski's test, also known simply as Salkowski test, is a qualitative chemical test, that is used in chemistry and biochemistry for detecting a presence of cholesterol and other sterols. This biochemical method got its name after German biochemist Ernst Leopold Salkowski, who is known for development of multiple new chemical tests, that are used for detection of different kinds of molecules (besides cholesterol and other sterols also for creatinine, carbon monoxide, glucose and indoles). A solution that has tested positive on the Salkowski's test becomes red and gets yellow glow.
Basic information
Procedure
For Salkowski test's procedure one needs a sample, that is to be tested for sterols, as well as chloroform and concentrated sulfuric acid that represent Salkowski's reagent. Usually the solution of chloroform and the sample is prepared first and later treated with concentrated sulfuric (VI) acid. After that the whole solution needs to be shaken well. It is important to use only dried glassware, as dehydration reaction occurs during the test's procedure.
A solution that has tested positive on this qualitative chemical test exhibits two distinct layers in a test tube; the upper layer (chloroform) gets blueish red to violet colour, while the layer of sulfuric acid becomes yellow to green, with greenish glow being visible. If a sample does not contain any cholesterol or other sterols, colour of the tested solution remains unchanged and retains its original colour.
Salkowski test can also be used to test the presence of indoles (crystalline alkaloids that are a degradation products of proteins, containing tryptophan). In such cases a sample is treated with nitric acid and 2% solution of potassium nitrite, with positive reaction being shown by presence of red colour.
Chemistry of the test
Treating a solution of a sample, containing sterols, with chloroform and highly hygroscopic sulfuric acid, leads to a dehydration reaction (two water molecules are removed from two cholesterol molecules) and formation of new double bonds. During the chemical reaction two sterols bind together and bisterol (bisteroid) is formed; bi-cholestadien (double cholestene with two double bonds) in a case of cholesterol. Red colour of a solution is a consequence of bi-sulfonic acid of a bi-cholestadien, which is a product of sulfuric acid sulfonating bi-cholestadien.
References
Biochemistry detection methods
Salkowski test for cholesterol – Its principle and procedure | Salkowski's test | Chemistry,Biology | 558 |
64,636,692 | https://en.wikipedia.org/wiki/HAT-P-36 | HAT-P-36, also referred to as Tuiren is a 12th magnitude G-type main-sequence star estimated to be approximately 958 light-years away from Earth in the constellation Canes Venatici. HAT-P-36 is too faint to be seen with the naked eye, but it is possible to view it with binoculars or a small telescope. In 2012 a hot Jupiter-type exoplanet was discovered orbiting HAT-P-36 with an orbital period of about 1.3 Earth days. In December 2019, HAT-P-36 was named Tuiren and its planetary companion, HAT-P-36b, was named Bran as a result of Ireland's contribution to the 2019 NameExoWorlds campaign. Bran has a mass approximately 1.8 times that of Jupiter and a radius 1.2 times larger.
Etymology
HAT-P-36 and its planet are named after characters from The Birth of Bran, a story in the book Irish Fairy Tales by James Stephens. The book is a re-telling of various stories from Irish folklore. Tuiren was the aunt of the mythical hero Fionn mac Cumhaill and was turned into a hound by the fairy Uchtdealbh after Tuiren married her husband. Bran and Sceólan were the two puppies mothered by Tuiren while she was a dog. They were cousins of Fionn mac Cumhaill. The names were proposed by John Murphy, a teacher at Regina Mundi College, Cork.
Planets
HAT-P-36b (Bran) was discovered in 2012 by the HATNet Project using the transit method. A search for transit timing variation did not result in detection of additional planets in the system as at 2021. Surprisingly, a planetary orbital period increase by 0.014 seconds per year was detected by 2021.
References
G-type main-sequence stars
Canes Venatici
Stars with proper names
Planetary systems with one confirmed planet
Planetary transit variables | HAT-P-36 | Astronomy | 404 |
51,015,173 | https://en.wikipedia.org/wiki/Neohygrocybe%20ingrata | Neohygrocybe ingrata is a species of agaric (gilled mushroom) in the family Hygrophoraceae. It has been given the recommended English name of dingy waxcap. The species has a European distribution, occurring mainly in agriculturally unimproved grassland. Threats to its habitat have resulted in the species being assessed as globally "vulnerable" on the IUCN Red List of Threatened Species.
Taxonomy
The species was first described as Hygrocybe ingrata from the Faroe Islands in 1945. Molecular research, based on cladistic analysis of DNA sequences, has, however, shown that it does not belong in Hygrocybe sensu stricto. Instead, the species has been moved into the related but separate genus Neohygrocybe, as already proposed on morphological grounds by Czech mycologist Josef Herink in 1958.
Description
Basidiocarps are agaricoid, up to 110 mm (4 in) tall, the cap convex becoming flat, up to 60 mm (2.5 in) across. The cap surface is smooth, dry, often uneven, buff to yellowish brown, darker brown when old. The lamellae (gills) are waxy, thick, cream becoming pale brownish. The stipe (stem) is smooth, cream becoming brownish when old, lacking a ring. When cut, the whitish flesh turns slowly reddish brown and has a slightly chemical smell. The spore print is white, the spores (under a microscope) smooth, inamyloid, ellipsoid, measuring about 7 to 9 by 5 to 6.5.5 μm.
Distribution and habitat
The dingy waxcap is widespread but generally rare throughout Europe. Like most other European waxcaps, it occurs in old, agriculturally unimproved, short-sward grassland (pastures and lawns).
Recent research suggests waxcaps are neither mycorrhizal nor saprotrophic but may be associated with mosses.
Conservation
Neohygrocybe ingrata is typical of waxcap grasslands, a declining habitat due to changing agricultural practices. As a result, the species is of global conservation concern and is listed as "vulnerable" on the IUCN Red List of Threatened Species. The species is included in national Red Lists of 13 European countries and is regarded as (critically) endangered in Croatia, Czech Republic, Denmark, Finland, France, Germany, Lithuania, Poland, and Switzerland.
See also
List of fungi by conservation status
References
Fungi of Europe
Fungi described in 1945
Fungus species | Neohygrocybe ingrata | Biology | 524 |
22,613,007 | https://en.wikipedia.org/wiki/Fertilizer%20burn | Fertilizer burns occur when the use of too much fertilizer, the wrong type of fertilizer, or too little water with a fertilizer causes damage to a plant. Although fertilizer is used to help a plant grow by providing nutrients, too much will result in excess salt, nitrogen, or ammonia which have adverse effects on a plant. An excess of these nutrients can damage the plant's ability to photosynthesize and cellularly respire, causing visible burns. The intensity of burns determine the strategy for recovery.
Background
Fertilizers contain nutrients that increase plant growth by increasing the rate of photosynthesis (the process in which plants uptake water and nutrients to create sugar) and cellular respiration (the process in which carbon dioxide and sugar is broken down to be used as energy, releasing oxygen). Nutrients and water enter the plant through the plants’ root cell membranes (the barrier separating the inside of the root cells from the outside) via osmosis (the movement of water and small nutrients through a membrane to equalize the concentration of a substance on each side of the membrane). Fertilizer burns occur when the use of fertilizers inhibit the above processes from working correctly and damage the plant.
Salt index and effects
Fertilizers contain differing salt concentrations which alter their 'salt index.' A salt index measures the relative change in osmotic pressure in water after a given salt has been added compared to sodium nitrate, which is assigned a value of 100. Salt indexes can have some relation to the rate of fertilizer burn in plants, with fertilizers of a salt index above 20 not being recommended for use with particularly sensitive crops.
Below is a chart of salt indexes and percent nitrogen of some of the most commonly used fertilizers.
An abundance of nitrogen can cause fertilizer burns. The concentration of nitrogen in a plant is important in terms of avoiding fertilizer burns.
The salt index of fertilizer can change the osmotic pressure, allowing the plant to absorb more or less water and nutrients. When a fertilizer has a high salt concentration, it will have a high salt index and vice versa for a low salt concentration. A correct salt index (in terms of the given plant and fertilizer) will result in high osmotic pressure. The incorrect salt concentration will result in low osmotic pressure, which can cause a fertilizer burn.
High Osmotic Pressure
High osmotic pressure is when there is a higher concentration of salts inside the root cell membrane, so water moves through the membrane to equalize the concentration, bringing nutrients across the membrane as well. The rate of photosynthesis and cellular respiration will increase. When there is a high osmotic pressure, fertilizer is working correctly.
Low Osmotic Pressure
Low osmotic pressure is when there is a higher concentration of salts outside the root cell membrane, so water will not move across the membrane. Water may even leave the root system in an attempt to equalize the concentration of salts in the soil. When there is a low osmotic pressure, the fertilizer is working incorrectly and the plant may experience a fertilizer burn.
Causes and pathophysiology
Fertilizer burns are caused by adding too much salt and or nutrients to the soil surrounding a plant. Dry, overheated, and sunburnt plants are most susceptible to fertilizer burns. There are five ways that the use of fertilizer could cause burns.
Use of too much fertilizer of the correct salt index. This causes a buildup of salts and nutrients in the soil and thus a fertilizer burn from low osmotic pressure.
Use of a fertilizer with too high of a salt index. This will cause a buildup of salt and nutrients in the soil and thus a fertilizer burn from low osmotic pressure.
Use of a fertilizer of the correct salt index but too little water. This will cause a fertilizer burn by starving the plant from water.
Use of a fertilizer that contains too much nitrogen. This will affect the cellular respiration of a plant, causing a fertilizer burn.
Use of a fertilizer that produces or has excess ammonia. The ammonia pulls water from the roots. The plant will respond as it does in a drought and this will cause a fertilizer burn by starving the plant from water.
Each of these five causes can be grouped into one of three explanations of the fertilizer burns:
Fertilizer burns due to low osmotic pressure.
With water not entering the plant, the plant will respond as it does in a drought. The plant will not photosynthesize, inhibiting sugar production, cellular respiration, and plant growth resulting in direct damage - a fertilizer burn.
Fertilizer burns due to too little water.
When too little water accompanies the high concentration of salts in fertilizer, the salts will absorb some of the water, leaving very little for the plant. The plant will respond as it would in a drought. The plant will not photosynthesize or cellularly respire, resulting in a fertilizer burn.
Fertilizer burns due to too much nitrogen.
Too much nitrogen can stop the production and accumulation of carbohydrates, inhibiting cellular respiration. Without cellular respiration, the plant's function will decline. Root rot may occur, during which the roots may incorrectly absorb nutrients and water, as the harmful nutrients are more likely to be absorbed. The lower leaves on the plant may die, and the rest of the plant will start to decline in function, portraying the fertilizer burn.
Signs and symptoms
The beginning signs of fertilizer burn include white salt marks and crust in the plant container and/or around the roots. The salt marks portray that there is an excess of salt and a buildup in the soil. When fertilizer burns continue,
The leaves of the plant will turn brown and die.
The root growth will stop.
The roots may turn brown indicating root rot.
Treatment
Recovery from fertilizer burns depends on the severity and the cause.
If a plant is burnt due to high salt concentration, there may be white marks and crusts around the plant (easily identifiable in potted plants). There are two options in terms of recovery.
Remove the plant and its roots from the pot, carefully clean the roots and repot the plant. Fertilizer can be reintroduced slowly to allow for slow, healthy recovery.
Water the plant heavily to wash the accumulation of salt away.
If a plant is burnt due to drought-like circumstances, the soil may be dry, and the plant will appear wilted. The best option in terms of recovery is to water the plant with more water, maintaining damp soil. Stop fertilizer usage until the plant is hydrated.
If a plant is burnt due to an abundance of nitrogen or ammonia, stop fertilizer usage and continue to water. If there is severe root rot, the function may not be able to recover and the plant may die.
See also
Abiotic stress
Bacterial leaf scorch
Biotic stress
Chlorosis
Fertilizer
Leaf scorch
Ozone
Soil salinity
References
Fertilizers
Physiological plant disorders | Fertilizer burn | Chemistry | 1,491 |
166,352 | https://en.wikipedia.org/wiki/Sides%20of%20an%20equation | In mathematics, LHS is informal shorthand for the left-hand side of an equation. Similarly, RHS is the right-hand side. The two sides have the same value, expressed differently, since equality is symmetric.
More generally, these terms may apply to an inequation or inequality; the right-hand side is everything on the right side of a test operator in an expression, with LHS defined similarly.
Example
The expression on the right side of the "=" sign is the right side of the equation and the expression on the left of the "=" is the left side of the equation.
For example, in
is the left-hand side (LHS) and is the right-hand side (RHS).
Homogeneous and inhomogeneous equations
In solving mathematical equations, particularly linear simultaneous equations, differential equations and integral equations, the terminology homogeneous is often used for equations with some linear operator L on the LHS and 0 on the RHS. In contrast, an equation with a non-zero RHS is called inhomogeneous or non-homogeneous, as exemplified by
Lf = g,
with g a fixed function, which equation is to be solved for f. Then any solution of the inhomogeneous equation may have a solution of the homogeneous equation added to it, and still remain a solution.
For example in mathematical physics, the homogeneous equation may correspond to a physical theory formulated in empty space, while the inhomogeneous equation asks for more 'realistic' solutions with some matter, or charged particles.
Syntax
More abstractly, when using infix notation
T * U
the term T stands as the left-hand side and U as the right-hand side of the operator *. This usage is less common, though.
See also
Equals sign
References
Mathematical terminology | Sides of an equation | Mathematics | 369 |
261,581 | https://en.wikipedia.org/wiki/Sonology | Sonology is a neologism used to describe the study of sound in a variety of disciplines.
In medicine, the term is used in the field of [imaging] to describe the practice of medical ultrasonography. According to some scholars, sonology may represent a more advanced application of clinical sonography, chiefly due to the requirement for the use of critical application of both cognitive and radiographic skills in making the diagnostic determination at the time of bedside application of focused ultrasound.
The term is also used to describe interdisciplinary research in the field of electronic music and computer music, drawing upon disciplines such as acoustics, electronics, informatics, composition and psychoacoustics. This sense of the term is widely associated with the Institute of Sonology, which was established by composer Gottfried Michael Koenig at the University of Utrecht in 1967 and later moved to the Royal Conservatory of The Hague in 1986. The term has also been adopted to describe the study of electronic music at other institutions, including the Center for Computational Sonology (now "Sound and Music Computing") at the University of Padua, Kunitachi College of Music in Tokyo, at the Catalonia College of Music in Barcelona and the Federal University of Minas Gerais in Brazil.
References
Sound
Electronic music
Neologisms | Sonology | Chemistry | 254 |
58,621,601 | https://en.wikipedia.org/wiki/Autoimmune%20GFAP%20astrocytopathy | Autoimmune GFAP Astrocytopathy is an autoimmune disease in which the immune system of the patient attacks a protein of the nervous system called glial fibrillary acidic protein (GFAP). It was described in 2016 by researchers of the Mayo Clinic in the United States.
GFAP is an intermediate filament (IF) protein that is expressed by numerous cell types of the central nervous system (CNS) including astrocytes. The destruction of astrocytes can lead to the development of a glial scar.
There are multiple disorders associated with improper GFAP regulation and glial scarring is a consequence of several neurodegenerative conditions. The scar is formed by astrocytes interacting with fibrous tissue to re-establish the glial margins around the central injury core and is partially caused by up-regulation of GFAP.
Signs and symptoms
The reported symptoms are:
myelitis (68.4%)
headache (63.2%)
abnormal vision (63.2%)
fever (52.6%)
ataxia (36.8%)
psychosis (31.6%)
dyskinesia (15.8%)
dementia (15.8%)
seizure (10.5%)
Under MRI these patients show a characteristic radial enhancing and laminar patterns. In an early report, most patients had brain abnormalities (89.5%), of which eight (42.1%) revealed the characteristic radial enhancing and laminar patterns. Cortical abnormalities were found in one-fifth of patients (21.1%). Other abnormalities were found in the hypothalamus, midbrain, pons, medulla cerebellum, meninges, and skull. Eleven patients had longitudinally extensive spinal cord lesions. CSF abnormalities were detected in all patients.
Clinical courses
GFAP autoimmunity comprises a spectrum of presentations of meningoencephalomyelitis. Specifically, some courses can be described as relapsing autoimmune meningoencephalomyelitis.
Seropositivity distinguishes autoimmune GFAP meningoencephalomyelitis from disorders commonly considered in the differential diagnosis.
The clinical presentations include:
meningoencephalomyelitis
encephalitis
movement disorder (choreoathetosis or myoclonus)
anti-epileptic drugs (AED)-resistant epilepsy
cerebellar ataxia
myelitis
optic neuritis
Some clinical courses could be coincident with neuromyelitis optica clinical cases.
Causes
The reason that anti-GFAP autoantibodies appear is currently unknown. There is the possibility that GFAP is not pathogenic, but just an unspecific biomarker of several heterogeneous CNS inflammations. According to this hypothesis, GFAP antibody itself does not induce pathological changes; it is only a biomarker for the process of immune inflammation
Diagnosis
Currently, it is diagnosed by the presence of anti-GFAP autoantibodies in CNS. Detection of GFAP-IgG in CSF by IFA and confirmation by GFAPα-CBA is recommended.
Treatment
Steroids and immunosuppressive treatment have been tried with limited effects.
References
Autoimmune diseases
Biology of bipolar disorder
Genes on human chromosome 17
Proteins | Autoimmune GFAP astrocytopathy | Chemistry | 714 |
81,636 | https://en.wikipedia.org/wiki/Unimog | The Unimog (pronunciation in American English: YOU-nuh-mog; British English: YOU-knee-mog; German: , ) is a Daimler Truck line of multi-purpose, highly offroad capable AWD vehicles with power take-off (PTO) driveshafts that since 1948 can be used with additional equipment in the roles of tractors, light trucks and lorries, for snow plowing, in agriculture, forestry, rural firefighting, in the military, even in rallying and as recreational vehicles. The frame is designed to be a flexible part of the suspension, not to carry heavy loads.
Conceived in 1944 in response to the Morgenthau Plan, former DB airplane engine engineers developed prototypes under occupation. The small universally-applicable motorised 25hp workhorse should be able to fit over two rows of potatoes to work on fields like a slow agricultural tractor, but with four equal size wheels on portal axles, coil spring suspension, and many gears, it was designed to also run fast on roads like a truck. Unimog production started in 1948 at in Göppingen. When larger production numbers were needed, Daimler-Benz took over manufacture of the Unimog in 1951, and first produced it in their Gaggenau plant, and the Unimog was sold under the Mercedes-Benz brand. However, the first Unimog to feature the three-pointed Mercedes-Benz star instead of the Boehringer bullhead was only introduced in 1953. From the 1970s, the more tractor-like MB-trac series was offered before it was outsourced in 1990. Since 2002, the Unimog has been built in the Mercedes-Benz truck plant in Wörth am Rhein in Germany. The Mercedes-Benz Türk A.Ş. plant assembles Unimogs in Aksaray, Turkey. Unimogs were also built in Argentina (first ever country to do so outside Germany) by Mercedes-Benz Argentina S.A. under licence from 1968 until 1983 (with some extra units built until 1991 off the assembly line from parts in stock) in the González Catán factory near the city of Buenos Aires, as stated in the book "El Unimog en el Ejército Argentino", by Argentine author and historian Gaston Javier Garcia Loperena in 2015.
The first model was designed by Albert Friedrich and Heinrich Rößler shortly after World War II to be used in agriculture as a self-propelled machine providing a power take-off to operate saws in forests or harvesting machines on fields. It was designed with rear-wheel drive and switchable front-wheel drive, with equal-size wheels, in order to be driven on roads at higher speeds than standard farm tractors. With their very high ground clearance and a flexible frame that is essentially a part of the suspension, Unimogs are not designed to carry as much load as regular trucks.
Due to their off-road capabilities, Unimogs can be found in jungles, mountains and deserts as military vehicles, fire fighters, expedition campers, and even in competitions like truck trials and Dakar Rally rally raids. In Western Europe, they are commonly used as snowploughs, municipal equipment carriers, agricultural implements, forest ranger vehicles, construction equipment or road–rail vehicles and as army personnel or equipment carriers (in its armoured military version). New Unimogs can be purchased in one of two series: medium series 405, also known as the UGN ("Geräteträger" or equipment carrier), and heavy series 437, also known as the UHN ("Hochgeländegängig" or highly mobile cross country).
Etymology
The name Unimog is an acronym for the German "UNIversal-MOtor-Gerät", Gerät being the German word for a piece of equipment (also in the sense of device, machine, instrument, gear, apparatus). It was created by German engineer Hans Zabel, who made the note Universal-Motor-Gerät on one of the technical drawings for the Unimog. Later, the Universal-Motor-Gerät was shortened to the acronym Unimog. On 20 November 1946, the name Unimog was officially unveiled. Since 1952, Unimog has been a brand of Daimler Truck.
Features
Design
The Unimog's characteristic design element is its chassis: a flexible ladder frame with short overhangs, and coil sprung beam portal axles with a central torque tube and transverse links. Having portal axles, the wheels' centres are below the axle centre, which gives the Unimog a high ground clearance without the need for big tyres. The coil sprung axles with torque tubes allow an axle angle offset of up to , giving the wheels a wide range of vertical movement to allow the truck to drive over extremely uneven terrain, even boulders of one metre in height.
Unimogs are equipped with high visibility driving cabs to enable the operator to see the terrain and more easily manipulate mounted tools. The newest implement carrier Unimog models can be changed from left-hand drive to right-hand drive in the field to permit operators to work on the more convenient side of the truck. The ability to operate on highways enables the Unimog to be returned to a home garage or yard to thwart vandalism.
Equipment
Unimogs can be equipped with front and rear tool mounting brackets and hydraulic connections to allow bucket loaders and hydraulic arms to be used. Most units have a power takeoff (PTO) connection to operate rotary equipment such as snow brooms, snow blowers, brush mowers, loaders or stationary conveyor belts.
Variants
Unimogs are available with short wheelbases for implement carrier operations or long wheelbases for all-terrain cargo carrying operations. Currently (2022), Daimler Trucks offers the 437.4 heavy series and the 405 implement carrier series. Starting in 1951 having purchased the traditional Unimog from Boehringer, Daimler-Benz started making the Unimog S series in the mid-1950s and added light, medium and heavy series to the model lineup in the 1960s and 1970s, before they successively reduced the available models during the 1990s to end up with the modern implement carrier and the heavy series today.
Originally, the traditional Unimog 70200 was a rather small agricultural tractor, measuring just in length. It was only offered as a Cabrio with a canvas roof. The engine power output of proved to be insufficient for many applications. To accommodate customer needs, a longer wheelbase version, a proper cab and more powerful engines (up to ) were introduced soon after Daimler-Benz took over Unimog manufacture; the traditional Unimog evolved into its final stage, the 411-series. Yet, Daimler-Benz decided that an entirely new, more powerful version of the Unimog would be required to meet future customer expectations. This Unimog version would later be known as 406-series.
The military Unimog S series is the first Unimog designed to be an offroad truck rather than a tractor, and it is the only series production Unimog that has an Otto engine. Daimler-Benz designed a new frame for it, but it still shares its drivetrain with the 411-series.
With the introduction of the 406-series in 1962, Daimler-Benz laid the foundation for a completely new Unimog model family, the 406-based medium series (in the 1960s known as heavy series). It was produced until 1994. Unimogs belonging to the medium series are the series 403, 413, 406, 416, 426, and 419. These models were offered with three different wheelbases (, , ) and two engines, the straight-four and straight-six direct injected Diesel engines OM 314 and OM 352, ranging from . The light series 421 and 431 share their frame design with the 411-series, but borrow their drivetrain and cab design from the 406-series, which is why they also count as 406-related Unimogs.
The heavy series Unimogs were introduced in 1974, and first featured the edgy cab, which is still a design feature of the Unimog today. The first heavy series Unimog was the 425-series, which was available from 1976. Soon after, the 435-series and 424-series followed, which caused a decline in Unimog 406 sales.The 425 was available with a wheelbase of , the 424 with and , and the 435 with , and . The introduction of new engines starting in 1986 caused a shift in the series numbers, but leaving the vehicles mostly unchanged otherwise. The 424 became 427 and both 425 and 435 were joined together and became 437. A derivative of the 437-series, the 437.4-series is still in production today.
In 1988, after declining Unimog sales, Daimler-Benz launched a new strategy that was supposed to increase sales and make the Unimog more profitable, called "Unimog-Programm 1988". New models introduced with this programme were the new light series 407 and medium series 417, which ought to replace all Unimog 406-related series. 407- and 417-series were replaced after just four years, in 1992, with the 408- and 418-series. in 2000, these two models were replaced with the current 405 implement carrier series, making the 437.4 and the 405 the only remaining Unimog series.
Technical description
Chassis
Like other trucks, but unlike agricultural tractors, the Unimog is a body-on-frame vehicle with short overhangs. The original Unimog was made with a plane ladder frame and a wheelbase of 1720 mm. Later, the wheelbase was extended several times to accommodate customer needs. Starting in the mid-1950s, with the introduction of the Unimog 404, the frame received a drop. Originally, this was done to make space for a spare tyre, but soon engineers found out that the new frame would improve the torsion performance, which is why all following Unimog series also received a frame with a drop. Several mounting brackets, additional cross members and tool boards were offered as factory options for the frame.
Suspension
The Unimog has live front and rear axles that have portal gears (portal axles). Such axles have a lifted axle centre, but the wheels' centre remains unchanged, meaning that a high ground clearance can be achieved with small wheels and tyres. Unlike "regular" trucks, the Unimog has coil springs with hydraulic shock absorbers rather than leaf springs, as coil springs provide more spring travel. The axles themselves have only one longitudinal pivot point each, the so-called torque tubes. The torque tubes contain the drive shafts and connect the axles' differential gearboxes to the Unimog gearbox, but being also parts of the suspension system, the torque tubes prevent longitudinal movement of the axles, whilst still allowing limited vertical movement. Lateral axle movement is prevented by panhard rods and transverse links. This design results in extreme axle angle offsets of up to possible.
A wide variety of wheels and tyres were available for the Unimog. Originally, the first Unimog was equipped with 6.5–18 in tyres designed for both on- and offroad use. Later, bigger wheels and tyres with different tread patterns were available, reaching from agricultural tractor tread patterns to massive bar tyre treads to low pressure ballon tyre treads. Until 1973, drum brakes were standard for all Unimogs, until they were replaced by disc brakes, however, until 1989, drum brakes remained an option for Unimogs of the 406-family. The steering system used to be a screw-and-nut system until 1970. Then it was replaced by a power assisted ball-and-nut system for the 406-series.
Drivetrain
The classical Unimog is rear-wheel drive vehicle, meaning that the rear axle is directly connected to the gearbox. Turning on front wheel drive automatically locks both axles, without torque compensation. The mechanical lever that turns on all wheel drive has a third position that locks front- and rear differentials. As of 1963, a pneumatic power switch was used instead of a lever. Due to the reduction gears inside the portal axles, the rotational frequency of the driveshafts inside the torque tubes is relatively high, meaning that the amount of torque they have to withstand is fairly low.
Gearbox
Traditionally, the Unimog has a splitter gearbox. Over the years, three different base gearbox designs have been used, all following the same principle, and having four gears and two ranges (called groups) and an additional direction gear. Those designs were UG-1/xx, UG-2/xx, and UG-3/xx. UG is an abbreviation for Unimog-Getriebe (Unimog-Gearbox), the number after the slash resembles the input torque in kp·m (=9.80665 N·m). Until 1955, the Unimog base gearbox UG-1 was a constant-mesh countershaft gearbox, it was then upgraded with synchroniser rings to a synchromesh gearbox. However, the synchromesh-version was only used for the 404-series, and the constant-mesh version remained the standard gearbox for the 411-series. In 1957, the synchromesh-version became an option for the 411-series, before it became the standard gearbox for all Unimogs in 1959. The following gearbox versions UG-2 and UG-3 were made as synchromesh versions only.
There are different layouts of the gearbox, namely F-layout and G-layout as well as their upgraded layouts, not having particular names. The F-layout is the original gearbox layout and is limited to the first two gears in the first range as it does not have selector sleeves, meaning that in total there are six forward gears. Instead of a reverse gear, the gearbox has its direction gear, which, in theory, can be used to reverse any gear. Due to the lacking shifting sleeves however, the reverse direction can only be used in the first range, which itself is limited to the first two gears, resulting in only two reverse gears (resulting in six forward and two reverse gears). To operate the gearbox, there is only one shift lever with a six-speed H-layout, the gearbox shifts its ranges automatically. An additional shift lever is used for shifting into reverse. The G-layout has an additional reduction gearbox, which can be used in all gears. This effectively doubles the number of gears (twelve forward and four reverse gears). This reduction gearbox was also available with an additional crawler gear, which can only be used in the first range (twenty forward and eight reverse gears). As of 1976, shifting sleeves were added and a four-speed-H-layout replaced the six-speed-H-layout, which allows using all gears in all ranges. With the introduction of the UG-3-gearbox, the standard gearbox-shifter-layout was changed to an eight-speed-H-H-layout, with eight gears on one lever, without any additional switches. When shifting from "4th" into "5th" gear, the gearbox automatically shifts into range 2 and back into gear 1. Crawler gearboxes were offered as a factory option for the UG-3 gearbox as well, resulting in 24 gears. The design with the additional direction gear was kept, which means that all 24 gears can also be used in reverse mode. Since the highest final gear ratio allows top speeds of up to 110 km/h, and the reverse gear only comes with a small reduction of 1:1.03, the top speed in reverse mode is more than 100 km/h. To prevent such high reverse speeds, a lock for the second range was available as a factory option, allowing only the first range (gears "1" to "4") in reverse mode.
Engine
The initial Unimogs were equipped with passenger car engines, the first Unimog series to receive a truck engine was the 406-series in 1963. All engines use the Diesel principle, except for engines used for the Unimog 404-series and the first four Unimog prototypes, which use the Otto principle. The following engines were used as of 1947, with M being Otto and OM being Diesel engines (the list is incomplete):
M 136
M 130
M 180
OM 636
OM 621
OM 615
OM 616
OM 312
OM 314
OM 352
OM 353
Cab
Traditionally, three different cab options were available for the Unimog: An open roof cab (Cabrio), single cab and double cab, with the single cab being the most popular. Because the Unimog was designed to be a better agricultural tractor, its original design did not include a closed cab (as agricultural tractors in Germany usually did not have a closed cab in the 1940s). The first Unimog series to be officially offered with a cab was the 401-series. However, the first cabs were made by Westfalia in Rheda-Wiedenbrück and then shipped to the Unimog plant in Gaggenau for assembly. These cabs are known as Westfalia type B or simply ('frog's eye'). Starting in 1957, a new cab with 30% more volume, called Westfalia type DvF, Typ D, (Type D, widened cab), was used. Both Westfalia cabs were fairly narrow and came with the problem of engine heat causing high cabin temperatures. The first Unimog that was designed with a cab was the series 406. Just for the purpose of manufacturing cabs, Daimler-Benz built a new 1000-Megapond-sheet-panel-press in the Unimog plant. It was planned that the double cab parts would also be produced with this press, instead, the double cabs were manufactured by Wackenhut in Nagold. In 1974, the current heavy-duty-series' cab was introduced. Its basic design has not been changed since. The equipment carrier versions' cab on the other hand has received several modifications since its introduction in the late 1980s, with the current version being introduced in 2000.
Pneumatics and hydraulics
The original Unimog was offered with a pneumatic system. This system was used for powering all auxiliary devices as well as the three-point linkages. As of October 1961, a hydraulics system became an option, and as of 1963, the hydraulics system became standard, but unlike the pneumatics system, the hydraulics system was made by Westinghouse Air Brake Company in Hannover. With the introduction of the hydraulics system, the pneumatics system was solely used for operating the brakes.
Users
Military
The Unimog was never meant to be a military vehicle; Allied permission to develop the Unimog was granted only because Albert Friedrich, inventor of the Unimog, ensured that the Unimog would not have any military purpose. However, the Unimog has always been used as a military vehicle. 44 Unimogs of the first model, the Unimog 70200, served as combat engineer tractors in the Swiss army. They proved successful, and the Swiss army purchased 540 units of the 70200's successor, the Unimog 2010. These early Swiss military vehicles were known as ″Dieseli″. The Dieseli-Unimogs remained in service until 1989. Officers of the French army, then occupying forces in Germany, noted the Unimog testing at the Sauberg in the early 1950s and considered the Unimog useful for patrolling purposes. Soon after, the French army purchased Unimogs of the series 2010 and 401. The Unimog proved to be so successful that Daimler-Benz was ordered to develop an entirely new Unimog just for military purposes. This new model was supposed to be a small 1.5-tonne truck, capable of carrying 10 to 12 soldiers on its bed, at a speed of up to 90 km/h, rather than being an agricultural tractor. Being a NATO member state, France demanded that the military Unimog would have an engine running on petrol. Daimler-Benz decided to use an Otto cycle engine, the M 180, displacing 2.2 litres, and producing 85 PS (63 kW). The military Unimog would later be known as Unimog 404 or Unimog S.
In total, 64,242 units of the Unimog 404 were produced, which makes it the Unimog with the highest production figure. 36,638 Unimog 404 were purchased by the German Bundeswehr. Apart from the Bundeswehr, many different military forces have either used the Unimog in the past or still make use of it today. In addition to the military series 404, several civilian models have been adapted for military use. In Argentina, the series 426, actually a version of the civilian series 416 produced under licence, was made for the Argentinian, Chilean, Peruvian and Bolivian military. In total, 2643 units of the series 426 were made. The Argentinian made Unimog 431, which was a licensed version of the civilian series 421, was also used as a military vehicle, mainly as a self-propelled howitzer. Another civilian Unimog that was mainly used a military vehicle, is the series 418.
The military Unimogs are used as troop transportation vehicles, ambulances, and mobile command centers equipped with military communications equipment. The United States Marine Corps and United States Army uses the Unimog 419 as an engineer tractor, while the United States Army also uses Unimog vehicles to access remote installations. In total, 2416 Unimog 419 were made, and only used by United States Forces. Modern Unimogs also serve as military vehicles, and the current Unimog 437.4 chassis is used for the ATF Dingo. More than 5,500 Unimogs are in active service in the Turkish Armed Forces. They were produced by Mercedes-Benz Türk.
Civilian
Unimogs are used by the German emergency management agency Technisches Hilfswerk (THW),(literally Technical Relief Organization), by fire departments and municipalities as utility vehicles. They can be used as material handlers, auxiliary power providers (generators), and equipment carriers. Their ability to operate off-road, in high water, or mud, makes it easier to access remote areas in emergency situations. They are commonly used in snow removal where other vehicles might not be able to operate. Many Alpine towns and districts are equipped with one or more Unimog snow blowers to clear narrow mountain roads that have drifted closed.
In construction, Unimogs are used as carriers of equipment and, with the optional extended cabin, also of workers. They can be equipped with a backhoe, front loader, or other contracting equipment. On railroads, Unimogs are used as rail car movers and road-rail vehicles. They have also been used in mining areas, like seen in Gold Bridge, BC, Canada.
In agriculture, Unimogs are used to operate farm equipment. While most farm field implement operations are now performed by a tractor, Unimogs are used to haul produce, machinery and animals. They are also used around the farmyard to run chippers, grain augers, and conveyors.
Unimogs are also used as a prime mover, to pull heavy trailers, large wheeled conveyances and jet airliners. Often, only the front half, (an OEM part), is combined with a tailor-made rear.
Unimogs are used as tourist transport for jungle ecotourism or safaris.
North America
Unimogs have been uncommon in North America because of differing vehicle regulations and requirements from those in Germany, and due to the lack of a North American sales and support network. Most Unimog models found in North America have been imported by individual dealers or independent enthusiasts.
Between 1975 and 1980 the Case Corporation (now merged into CNH Global) imported the U-900 model into the United States and sold it through Case tractor dealerships as the MB4/94.
In 2002 DaimlerChrysler tried to re-enter the North American market with the Unimog and engaged in four years of aggressive marketing, which included activities such as; truck and trade shows, exposure on the television show Modern Marvels, numerous magazine articles and extensive demonstrations (both touring and on an individual basis). They were generally sold through Freightliner truck dealerships. Freightliner is a Daimler AG subsidiary. The UGN series was specifically manufactured for the North American market and was significantly different mechanically from its European counterpart. The UGN faced stiff competition in North America by manufacturers whose truck or equipment lines performed some of the same duties as the Unimog. Some of them are Caterpillar, John Deere, AM General, Sterling Trucks (also a Daimler AG subsidiary), and General Motors. After five years and selling only 184 Unimogs, Freightliner LLC exited the market. Daimler AG cited non-compliance with EPA07 emission requirements as the main reason for ceasing North American sales.
Motorsport
Unimogs have been used in three kinds of competition: Dakar Rally and other desert rally competitions, mud bogging, and slow-moving Truck Trials over obstacles.
Unimogs have won the truck class of the Dakar in 1982 and 1986, the latter an unexpected victory as the vehicle participated for Honda, primarily to provide support for the motorcycles of the team. High-powered factory-sponsored entries of truck companies aiming for the overall win have since taken the laurels, with Unimogs used mainly for service purposes.
Derivatives
MB-trac
In 1968 the Unimog department in Gaggenau began development of the MB-trac, a tractor based on the Unimog 403 drivetrain. It was produced by Daimler-Benz until 1991, when the product line was sold to Werner Forst- und Industrietechnik. Werner continues to produce it as the WF trac.
Military derivatives
The Unimog also serves as a technical platform for armoured vehicles like the ATF Dingo, a mine-protected utility and reconnaissance vehicle used by the German and other European Armed Forces (e.g. Belgium) for territorial defence purposes as well as in international missions.
In late Autumn 1956, Daimler-Benz started developing a new military version of the Unimog, the Unimog SH. It was based on the Unimog S and had a rear engine (German: Heckmotor), hence the name Unimog SH. Until 1960, Daimler-Benz completed 24 Unimog SH and sent them to AB Landsverk for final assembly. Initially, the Belgian Army intended to purchase these vehicle for their police forces in the Belgian Congo, but only 9 vehicles were actually sold to the Belgian forces; the 15 remaining vehicles were purchased by the Irish Army in 1972. They were intended as a stop-gap vehicle for use until the first Panhard M3 VTT APCs entered service in 1972. The type had excellent off-road capability but poor on-road handling due to a high centre of gravity and several accidents occurred as a result. A four-man dismountable squad was carried, but space was cramped, and in any case a four-man detachment was far too small for any sort of realistic military purpose. Other considerations were that the FN MAG gunner's position was too exposed. Eventually the Unimog Scout Cars arrived in Ireland in February 1972, their departure having been delayed by a local peace group who thought they were destined for the Provisional Irish Republican Army (PIRA). By mid-1978 all had been transferred to the Irish Army Reserve, the FCA. All were withdrawn by 1984, and two are preserved; one in the transport museum in Howth Co Dublin and one in the Muckleburgh Collection, England.
An updated version of the Unimog SH, the Unimog T was made for the German Bundeswehr in 1962. The German defence ministry decided not to purchase the Unimog T, which is why it was never put into series production. Further armoured vehicles developed in Germany using Unimog chassis are the UR-416, the Sonderwagen 4 and Condor 1 in Police service, and the ATF Dingo used by the Bundeswehr in Afghanistan. The French Aravis mine-protected vehicle, like the Dingo, based on the Special Chassis FGA 12.5. The Buffel, Mamba, RG-31, and RG-33 armoured personnel carriers from South Africa are based upon the Unimog driveline. The AV-VBL developed by Brazil's Tectran is also an AFV family based on the Unimog.
History
1940s
1945 – First prototype
Originally, the Unimog was developed in post-war Germany to be used as agricultural equipment. It was designed with equal-sized wheels, a mounting bracket in front, a hitch in the rear, and loading space in the center. This was to make it a multi-purpose vehicle that farmers could use in the field and on the highway.
Albert Friedrich was granted permission to develop the Unimog in November 1945, and entered a production agreement with Erhard und Söhne (Erhard and Sons) in Schwäbisch Gmünd on 1 December 1945. Development began on 1 January 1946. Soon after, Heinrich Rößler, the Unimog lead designer, joined the development team. The first prototype was ready by the end of 1946. The early prototypes were equipped with the M 136 Otto engine, because the development of the OM 636 Diesel engine had not been finished. The prototypes were similar to the later series production models. The original track width of was equivalent to two potato rows.
1947 – Production
The 25-PS (18 kW) OM 636 Mercedes-Benz Diesel engine became standard equipment in the first production Unimogs at the end of 1947. The original emblem for the Unimog was a pair of ox horns in the shape of the letter U. The first 600 units of the 70200 series Unimogs were built by Boehringer. This was done mainly for two reasons: Erhard und Söhne did not have the capacity to build the Unimogs and Boehringer (a former tool manufacturer) could evade dismantling.
1950s
In late 1950, Mercedes-Benz entered into a contract with Boeringer to take over production of the Unimog.
1951 – Daimler-Benz – Gaggenau manufacturing plant
Daimler-Benz modified the Unimog for mass production to create the series 2010 and in 1951, started its manufacture in their Gaggenau plant in Baden-Württemberg, where production continued until 2002.
1953 – The 401, 402 and the closed cab
In 1953, the Unimog was updated and the three-pointed Mercedes star began to appear on the bonnet, replacing the Unimog ox horn emblem. The new model became known as the series 401. A new series 402 with a long wheelbase chassis ( instead of ) also became available.
An enclosed driver's cab was available as an option from 1953, making the Unimog a true all-weather vehicle.
1955 – The 404 S
In 1955, the first Unimog 404 S series were produced. The primary customer of the 404 S was the Bundeswehr (literally Federal Defence, i.e. the West German Armed Forces), which was created in the mid-1950s in the era of the Cold War.
The 404 was intended to be a mobile cross-country truck, instead of an agricultural implement. The 404 S is the most popularly produced variant. 64,242 units were produced between 1955 and 1980. The oldest 404 known to exist is the first 1953 prototype, located in an East German museum.
1957
Starting in 1957, the Unimog 411 was offered with a synchromesh gearbox as an option, and in 1959, the synchromesh gearbox became standard.
1960s
The 406/416 middle series were produced beginning in 1963. They were equipped with the six-cylinder pre-combustion chamber Diesel engine OM 312 producing . The 406 and 416 are similar, The 416 having a longer wheelbase compared to for the 406. Starting in 1964, the 406-series was equipped with the direct injected OM 352 Diesel engine starting with and going up to ( for the Unimog 416).
Between the original Unimog and the middle series, Daimler-Benz developed a light series. The light series consisted of two separate Unimog series, the 421 and the 403. The 403, which basically is a 406-series with a 3.8-litre four-cylinder engine, has a wheelbase and was later supplemented by the 413-series, which is a four-cylinder-version of the 416-series (long wheelbase () model). The 421 is the successor of the 411-series and has a wheelbase. It is powered by a 2.2-litre passenger car Diesel engine.
The 100,000th Unimog (a 421) was built in 1966 in Gaggenau.
Argentina was the first country to manufacture the Unimog outside Germany. The first Unimog produced in the Mercedes-Benz Argentina S.A. factory in Gonzalez Catán, in the outskirts of Buenos Aires city, rolled off the assembly line on 1 September 1968.
The two models made in Argentina, are the 426 and 431. They are versions of the 416 respectively 431 produced under licence.
1970s
1972 – MB Trac
Despite originally being designed as an agricultural vehicle, the Unimog had more success as a multi-purpose tool carrier. To actually serve the agricultural market, Daimler-Benz designed a completely new agricultural tractor in 1972, the MB Trac. It is a body-on-frame design trac-tractor, has four big wheels of the same size, and all-wheel-drive, a slim bonnet, and an angular driver cab. In contrast to conventional tractors the cab is situated between the axles, similar to comparable four-wheel-drive tractors. There is no articulation between the front and rear sections, instead, the MB Trac has conventional steering.
A wide range of MB Trac tractors were offered, ranging from the entry model MB-trac 65 to the top model MB Trac 1800 intercooler. Daimler-Benz later merged the MB-trac with the agricultural machinery activities of Deutz AG. The manufacturing of the MB Trac series ceased in 1991.
1974 – Heavy series
In 1974, Mercedes-Benz presented the new Unimog U 120. It was the first model of the "heavy duty" Unimog series 425. The heavy duty series, or simply "heavy" series, extended the Unimog model lineup. The characteristic "edgy" bonnet introduced with the heavy Unimog series remains am Unimog style element to this day.
The series 425 have a wheelbase, 9 t permissible maximum mass and an OM 352 Diesel engine producing (shortly thereafter as U 125).
1975 – Series 435
Manufacture of the series 435 for the Bundeswehr began in 1975, as a successor of the Unimog S 404. The 435 was characterized by a long wheelbase of , or and shares its cab with the series 425.
1976 – Unimog models renamed
The new 424 "middle" series of Unimogs was produced starting from 1976. They share the cab with the series-425 and are designated U 1000, U 1300/L, U 1500, and U 1700/L with engine performance.
In the same period Daimler-Benz re-ordered the type designations for the older series. The classical round form series of the Unimog were now designated U 600/L, U 800/L, U 900 and U 1100/L. (The letter L stands for a long wheelbase, because most models were available in two wheelbase variants.)
The Unimog with the rounded driving cab became known as the light series. The new series with angular cab was divided by payload into a middle and heavy series. Some engines overlap – the Unimog nomenclature is not simple to understand (see below for notes on series names).
The long-proven Unimog-S (404), although with clearly decreasing production figures, was the only Unimog with an Otto cycle engine in the lineup.
With the exception of the entry-level model, all Unimogs for 1976 were equipped with four wheel disc brakes.
1977 – 200,000th Unimog
The 200,000th Unimog, a 424.121, was produced in 1977.
1980s
In 1980, production of the U 404 (Unimog S) ended.
The light and medium series 407 and 427 were introduced in 1985.
Production of the 406 and 416 ceased in 1988 and the 437-series was introduced the same year.
1990s
1992 – New light models
In the early 1990s, the new light models 408 (U 90) and 418 (U 110-U 140) with newly designed cabins were introduced to replace the predecessor models. The new very diagonal front portion gives the operator a good overview forward. The 408 features an asymmetric front bonnet, which is lower on the driver's side. This is supposed to permit the driver a good overview. A new ladder frame and progressively working coil springs to improve the Unimog's handling were implemented. In addition to that, the Unimog received a new tyre pressure adjustment system that can be operated whilst driving, an anti-skid system, new engines, and a "Servolock" mechanism for the hydraulic connection of implements.
1994 – The "Funmog"
In March 1994, Mercedes-Benz presented the design concept "Funmog", a luxury version of the Unimog, on the International Off-Road-Exhibition in Köln, Germany. It was based on the 408-series and only built for customers who special-ordered it. Until 1997, Daimler-Benz made exactly 12 units of the Funmog, out of which most were exported to Japan. The Funmog features chrome bull bars, and air horns, but lacks hydraulics and is limited to a total mass of 5,000 kg. Mercedes-Benz offered luxury options such as leather seats, fine carpeting and other interior modifications for the Funmog. Starting price was DM 140,000.
1995 – U 2450 L 6×6
In 1995, the Unimog U 2450 L 6×6 (437.156), an all-wheel-drive, 3-axle Unimog version, was presented.
1996 – UX 100
Mercedes-Benz presented the Unimog 409 (officially called UX 100) in 1996. It is the smallest Unimog model ever made and designed to slip speedily over sidewalks and around plants. Within a few years, production of the UX 100 was transferred to the Multicar subsidiary of Hako GmbH, who specialize in vehicles of this kind and size.
2000s
The all-new range of UGN models (405 series U 300, U 400, U 500) was introduced in 2000.
In August 2002 production ended in the Gaggenau plant after 51 years and more than 320,000 Unimogs being made, and started up in Mercedes-Benz's truck manufacturing plant in Wörth am Rhein. The U 3000, U 4000 and U 5000 models (UHN 437.4 series) were introduced at the same time.
At the Dubai Motor Show in December 2005, the "Unimog U 500 Black Edition" premiered as an offering to wealthy desert-dwellers. It is a similar luxury offering comparable to the Funmog.
Starting from June 2006 the UGN series was produced with BlueTec technology so that the Euro IV emission requirements would be met. The design designations changed from 405.100 to 405.101.
At the IAA 2006 commercial vehicle show in Hanover a new Unimog U 20 was presented, which was to be available at the end of 2007. The most striking feature is the cab over design with no vestigial front bonnet characteristic of the traditional Unimog. It has a total mass of 7,500 kg up to 8,500 kg. The underlying technology comes from the U 300. The driving cab is from the new Brazilian Accelo light truck (Caminhões Leves) series. The wheelbase is shortened to .
2010s
In August 2013, production of the next generation models commenced at the Wörth plant. The new models feature redesigned cabins and new engines that were claimed to meet the Euro VI emission standards.
Series numbers and models
Unimog series numbers like 401, 406, or 425 in this article are the factory numerical designation (in German "Baumuster", literally Construction Pattern). Unimogs also have a sales model number like U 80, U 120, or U 1350. Each series can have several model numbers, as they are equipped with different engines or chassis options.
Originally, the "U" model numbers were roughly equivalent to the horsepower of the engine (in German: PS):
A 424.121 with a wheelbase equipped with the OM 352 engine is a U 1000
A 427.100 with a wheelbase and the 100-PS 366 engines is also a U 1000.
Starting in 1976, model numbers added an extra 0 at the end. More recent model numbers may have three or four digits and sometimes do not relate to horsepower (the engine of the U 5000 is rated at 218 PS). The most recent models introduced since 2013 are:
The 437.4 series is intended for extreme offroad use, with the smaller U 4023 and larger U 5023 models, which are only available with 230 PS engines
The 405 series is intended for use with implements, with three digit model numbers. The first digit is related to the vehicle size (U 200, U 300, U400 and U 500 model ranges) and the second and third digits related to the engine power, starting from the 190 PS U 219 and going up to the 350 PS U 535.
See also
Bremach – similar vehicles built in Italy
Railcar mover
SCAM – similar vehicles built in Italy
Silant – similar vehicles built in Russia
Pinzgauer – similar vehicles built in Austria
Mercedes-Benz Zetros
Notes
References
Further reading
External links
Official website
Cab over off-road vehicles
Cab over vehicles
Engineering vehicles
Mercedes-Benz vehicles
Military trucks
Military vehicles of Germany
Off-road vehicles
Pickup trucks | Unimog | Engineering | 8,781 |
20,102,550 | https://en.wikipedia.org/wiki/Aladdin%20%28containers%29 | Aladdin is a brand notable for its line of character lunchboxes including Hopalong Cassidy, Superman, Mickey Mouse and The Jetsons. Today, Aladdin continues to be a food and beverage products brand and is owned by Pacific Market International, LLC of Seattle, Washington and Aladdin continues to be a kerosene lamps and wicks products brand and is owned by Hattersley Aladdin Ltd of the United Kingdom.
Aladdin Industries
Aladdin Industries was a vendor of lunchboxes, kerosene lamps, stoves and thermal food storage containers. It was founded in Chicago in 1908 by Victor Samuel Johnson, Sr. and incorporated as the Mantle Lamp Company. Aladdin Industries was created as a subsidiary of Mantle Lamp Company in 1914, specifically to manufacture vacuum bottles. The company was further diversified under former president Johnson's leadership. It was the maker of the first character lunchbox, using images of Hopalong Cassidy, in 1950.
In 1908, Johnson Sr., a Chicago soap salesman, became interested in kerosene mantle burners. Dissatisfied with the available kerosene lamps of the time, Johnson began selling U.S.-made mantle lamps. He incorporated his lamp sales business and called the company the Mantle Lamp Company of America. In 1912, the company began manufacturing mantle lamps that gave off a steady white light without smoke. They called these lamps Aladdin lamps after the magical lamp and wish-granting genie in the children's story.
In 1917, Johnson Sr. diversified the company's offerings and began producing insulated cooking dishes, known at the time as Aladdin Thermalware jars. These Thermalware jars were the company's first venture into heat and cold retaining dishes and are early cousins of the products in use today. In 1919, Johnson moved these jars into a new subsidiary he called Aladdin Industries. This subsidiary offered thermalware jars and vacuum ware and successfully sold and manufactured these products from 1919-1943.
In 1943, Johnson Sr. died and his son Victor S. Johnson, Jr. took over as president of Aladdin Industries, Inc. In 1949, in an effort to centralize operations, Johnson Jr. moved Aladdin's offices and manufacturing facilities to Nashville, TN.
Under Johnson Jr.'s management, Aladdin began producing metal lunch boxes in the 1940s. By the 1950s Aladdin was an industry leader in this category and would remain so for the next 30 years. Aladdin's dominance in lunch products resulted from a strategic move in the early 50s to license popular character images on its products. Hopalong Cassidy was the first character licensed product and in its first year, sales went from 50,000 units to 600,000 units. Subsequent branding included Superman, Mickey Mouse and The Jetsons.
In 1965 Aladdin Industries expanded their product line through the acquisition of the Stanley Bottle operation. This move helped solidify the company's position in the food and beverage container category by deepening their line of steel offerings.
In 1968, Aladdin introduced the insulated thermal tray, which revolutionized meal distribution for airlines, and then hospitals and other mass-feeding institutions which could, at last, keep hot foods hot and cold foods cold for long periods of time. Aladdin Industries incorporated Aladdin Synergetics as a new division for healthcare foodservice products. In 1998, this subsidiary was sold to Welbilt Corporation and was renamed Aladdin Temp-Rite. In 2002, Aladdin Temp-Rite was acquired by the Ali Group.
1980s – 2002
During the 1980s and 1990s Aladdin continued to grow and by the mid 1990s its Nashville operation grew to employ 1100 employees. At this time, foam insulated mugs grew in popularity and Aladdin's products were sold in grocery chains nationwide. Aladdin opened their Nashville factory on Murfreesboro Road, producing its first thermal products in July 2002.
Seattle-based company Pacific Market International, LLC purchased the Aladdin brand in 2002.
Current Aladdin brand
The Aladdin brand is now owned by the privately held Pacific Market International (PMI), and is headquartered in Seattle, Washington, with offices in Europe, Asia and Australia. As of 2009, PMI sells vacuum flasks and other thermal products manufactured under the Aladdin name.
Literary references
The protagonist in Penelope Fitzgerald's Booker prize shortlisted novel The Gate of Angels, set in 1912, uses one of the company's lamps (an "Aladdin") in the fictional college of St Angelicus, where the use of electricity or gas is not permitted.
See also
Lunch box
Aladdin Industries
Stanley bottle
References
External links
Aladdin Industries from The Tennessee Encyclopedia of History and Culture
A History of Aladdin Lamps—TeriAnn's Guide to Aladdin Mantle Lamps
1908 establishments in Illinois
2002 disestablishments in Tennessee
American companies established in 1908
Manufacturing companies based in Seattle
Manufacturing companies disestablished in 2002
Manufacturing companies established in 1908
Vacuum flasks | Aladdin (containers) | Physics | 1,004 |
5,298,371 | https://en.wikipedia.org/wiki/%CE%9418O | {{DISPLAYTITLE:δ18O}}
In geochemistry, paleoclimatology and paleoceanography δ18O or delta-O-18 is a measure of the deviation in ratio of stable isotopes oxygen-18 (18O) and oxygen-16 (16O).
It is commonly used as a measure of the temperature of precipitation, as a measure of groundwater/mineral interactions, and as an indicator of processes that show isotopic fractionation, like methanogenesis.
In paleosciences, 18O:16O data from corals, foraminifera and ice cores are used as a proxy for temperature.
It is defined as the deviation in "per mil" (‰, parts per thousand) between a sample and a standard:
‰
where the standard has a known isotopic composition, such as Vienna Standard Mean Ocean Water (VSMOW). The fractionation can arise from kinetic, equilibrium, or mass-independent fractionation.
Mechanism
Foraminifera shells are composed of calcium carbonate (CaCO3) and are found in many common geological environments. The ratio of 18O to 16O in the shell is used to indirectly determine the temperature of the surrounding water at the time the shell was formed. The ratio varies slightly depending on the temperature of the surrounding water, as well as other factors such as the water's salinity, and the volume of water locked up in ice sheets.
also reflects local evaporation and freshwater input, as rainwater is 16O-enriched—a result of the preferential evaporation of the lighter 16O from seawater. Consequently, the surface ocean contains greater proportions of 18O around the subtropics and tropics where there is more evaporation, and lesser proportions of 18O in the mid-latitudes where it rains more.
Similarly, when water vapor condenses, heavier water molecules holding 18O atoms tend to condense and precipitate first. The water vapor gradient heading from the tropics to the poles gradually becomes more and more depleted of 18O. Snow falling in Canada has much less H218O than rain in Florida; similarly, snow falling in the center of ice sheets has a lighter signature than that at its margins, since heavier 18O precipitates first.
Changes in climate that alter global patterns of evaporation and precipitation therefore change the background ratio.
Solid samples (organic and inorganic) for oxygen isotope analysis are usually stored in silver cups and measured with pyrolysis and mass spectrometry. Researchers need to avoid improper or prolonged storage of the samples for accurate measurements.
Extrapolation of temperature
Based on the simplifying assumption that the signal can be attributed to temperature change alone, with the effects of salinity and ice volume change ignored, Epstein et al. (1953) estimated that
a increase of 0.22‰ is equivalent to a cooling of 1 °C (or 1.8 °F).
More precisely, Epstein et al. (1953) give a quadratic extrapolation for the temperature, as
where T is the temperature in °C (based on a least-squares fit for a range of temperature values between 9 °C and 29 °C, with a standard deviation of ±0.6 °C, and δ is δ18O for a calcium carbonate sample).
Paleoclimatology
Ice cores
δ18O can be used with ice cores to determine the temperature from when the ice was formed.
Lisiecki and Raymo (2005) used measurements of δ18O in benthic foraminifera from 57 globally distributed deep sea sediment cores, taken as a proxy for the total global mass of glacial ice sheets, to reconstruct the climate for the past five million years.
The stacked record of the 57 cores was orbitally tuned to an orbitally driven ice model, the Milankovitch cycles of 41 ky (obliquity), 26 ky (precession) and 100 ky (eccentricity), which are all assumed to cause orbital forcing of global ice volume. Over the past million years, there have been a number of very strong glacial maxima and minima, spaced by roughly 100 ky.
As the observed isotope variations are similar in shape to the temperature variations recorded for the past 420 ky at Vostok Station, the figure shown on the right aligns the values of δ18O (right scale) with the reported temperature variations from the Vostok ice core (left scale), following Petit et al. (1999).
Biomineralized tissues
δ18O from biomineralized tissues may also be used in reconstructing past environmental conditions. In vertebrates, apatite from bone mineral, tooth enamel and dentin contains phosphate [PO4]3− groups which may preserve the oxygen isotope ratios of environmental water. Fractionation of oxygen isotopes in these tissues may be affected by biological factors such as body temperature and diet.
See also
Global meteoric water line (GMWL), relation between and (also known as )
Isotopic signature
Isotope analysis
Isotope geochemistry
Paleothermometer
Stable isotope ratio
References
Bioindicators
Isotopes of oxygen
Environmental isotopes
Geochemistry
Isotope excursions | Δ18O | Chemistry,Environmental_science | 1,070 |
43,339,210 | https://en.wikipedia.org/wiki/Hydroxybupropion | Hydroxybupropion (code name BW 306U), or 6-hydroxybupropion, is the major active metabolite of the antidepressant and smoking cessation drug bupropion. It is formed from bupropion by the liver enzyme CYP2B6 during first-pass metabolism. With oral bupropion treatment, hydroxybupropion is present in plasma at area under the curve concentrations that are as many as 16 to 20 times greater than those of bupropion itself, demonstrating extensive conversion of bupropion into hydroxybupropion in humans. As such, hydroxybupropion is likely to play a very important role in the effects of oral bupropion, which could accurately be thought of as functioning largely as a prodrug to hydroxybupropion.
Hydroxybupropion has two chiral centers and is a mixture of four possible enantiomers. In humans however, presumably due to steric hindrance, only (2R,3R)-hydroxybupropion and (2S,3S)-hydroxybupropion are formed.
Other metabolites of bupropion besides hydroxybupropion include threohydrobupropion and erythrohydrobupropion.
Pharmacology
Pharmacodynamics
Compared to bupropion, hydroxybupropion is similar in its potency as a norepinephrine reuptake inhibitor (IC50 = 1.7 μM), but is substantially weaker as a dopamine reuptake inhibitor (IC50 = >10 μM). Like bupropion, hydroxybupropion is also a non-competitive antagonist of nACh receptors, such as α4β2 and α3β4, but is even more potent in comparison.
Pharmacokinetics
Bupropion is extensively and rapidly absorbed in the gastrointestinal tract but experiences extensive first pass metabolism rendering its systemic bioavailability limited. Exact bioavailability has yet to be determined given an intravenous form does not exist. Absorption is suggested to be between 80 and 90%. Its distribution half-life is between 3–4 hours and exhibits moderate human plasma protein binding (between 82 and 88%) with the parent compound and hydroxybupropion displaying the highest affinity. Bupropion is a racemic mixture and is metabolized hepatically primarily via oxidative cleavage of its side chains by CYP2B6. Hydroxybupropion is the most potent of the metabolites. It is formed via the "hydroxylation of the tert-butyl group" by CYP2B6 and is excreted renally. Cmax values of hydroxybupropion are 4–7 times that of bupropion, while the exposure to hydroxybupropion is "10 fold" that of bupropion. Hydroxybupropion's elimination half-life is roughly 20 hours, give or take 5 hours and will reach steady state concentrations within 8 days.
Chemistry
Hydroxybupropion is a racemic mixture of (R,R)-hydroxybupropion and (S,S)-hydroxybupropion.
Research
Although there are patents proposing uses and formulations of this compound, hydroxybupropion is not currently marketed as a drug in and of itself and is only available for use in non-clinical research. Hydroxybupropion is not a scheduled drug or a controlled substance. One can access GLP (Good Lab Practice) documents detailing assays/techniques to further research and isolate this drug. Otherwise, there is little regulatory data available for hydroxybupropion at this time. Moreover, there is little information to suggest hydroxybupropion has an abuse potential. However, it has been studied as a possible therapeutic for alcohol and nicotine use as a codrug.
There are few clinical trials or toxicology studies assessing hydroxybupropion alone at this time. There are clinical studies which assess hydroxybupropion in conjunction with bupropion suggesting hydroxybupropion to be the primary form of the compound responsible for its clinical efficacy. Also, transdermal delivery of bupropion and hydroxybupropion has been assessed finding bupropion to be the superior candidate given its elevated diffusion rate through skin samples. There are few toxicology studies assessing hydroxybupropion alone at this time. However, there are some studies which assess this compound in conjunction with others or its parent compound.
See also
Radafaxine – a cyclised derivative of hydroxybupropion
Manifaxine – an analogue of radafaxine and hydroxybupropion
References
5-HT3 antagonists
Antidepressants
Cathinones
3-Chlorophenyl compounds
Convulsants
Human drug metabolites
Nicotinic antagonists
Norepinephrine reuptake inhibitors
Primary alcohols
Smoking cessation
Stimulants | Hydroxybupropion | Chemistry | 1,092 |
27,662,451 | https://en.wikipedia.org/wiki/Diamond%20grinding%20of%20pavement | Diamond grinding is a pavement preservation technique that corrects a variety of surface imperfections on both concrete and asphalt concrete pavements. Most often utilized on concrete pavement, diamond grinding is typically performed in conjunction with other concrete pavement preservation (CPP) techniques such as road slab stabilization, full- and partial-depth repair, dowel bar retrofit, cross stitching longitudinal cracks or joints and joint and crack resealing. Diamond grinding restores rideability by removing surface irregularities caused during construction or through repeated traffic loading over time. The immediate effect of diamond grinding is a significant improvement in the smoothness of a pavement. Another important effect of diamond grinding is the considerable increase in surface macrotexture and consequent improvement in skid resistance, noise reduction and safety.
History
The industry can be traced back to an event where a single diamond blade mounted on a concrete saw was used to groove concrete pavement in the late 1940s. Since that early tentative step, concrete grinding, grooving and texturing with diamond blades has developed into what is today a multimillion-dollar industry that is practiced worldwide.
One of the first uses of diamond grinding of highway pavement was in 1965 on a 19-year-old section of Interstate 10 in California to eliminate excessive faulting. The pavement was ground again in 1984 and in 1997, and it is still carrying heavy traffic as of 2006, more than 60 years after it was first constructed.
Process
Diamond grinding involves removing a thin layer at the surface of hardened PCC using closely spaced diamond saw blades. The level surface is achieved by running the blade assembly at a predetermined level across the pavement surface, which produces saw cut grooves. The uncut concrete between each saw cut breaks off more or less at a constant level above the saw cut grooves, leaving a level surface (at a macroscopic level) with longitudinal texture. The result is a pavement that is smooth, safe, quiet and pleasing to travel.
The diamond blades are composed of industrial diamonds and metallurgical powder. When grinding materials contain hard aggregate materials, a diamond blade with a soft bond is needed, which means that the metallurgical powders in the cutting segments of the blade wear fast enough to expose the diamond cutting media at the proper rate for efficient cutting. Conversely, to cut soft aggregates, a diamond blade with a hard bond is recommended.
Diamond grinding should not be confused with milling or scarifying. Milling is an impact process that chips small pieces of concrete from the pavement surface. Diamond grinding is a cutting process.
For grinding asphalt to remove old pavement, see pavement milling.
Applications
There are many surface issues that diamond grinding can improve or correct. Some of the surface imperfections that can be addressed by diamond grinding include: faulting at joints and cracks, built-in or construction roughness, polished concrete surfaces exhibiting inadequate macrotexture, wheel path rutting caused by studded tires, unacceptable noise level, slab warping caused by moisture gradient and construction curling, inadequate transverse slope and splash and spray reduction.
Cost-effectiveness
Diamond grinding is a cost-effective treatment, whether used alone or as part of an overall concrete pavement restoration (CPR) program. In most cases, the cost of diamond grinding is only about half the cost of bituminous overlays. This cost competitiveness, in conjunction with eliminating bituminous overlay problems (rutting, corrugation, poor skid resistance, drainage reduction, vertical clearance reduction) makes diamond grinding an alternative for many rehabilitation projects. Diamond grinding can be used as part of any preventive maintenance program for concrete pavements.
Caltrans reports that the average life of a diamond-ground surface is between 16 and 17 years. On average, more than 2,000 lane-miles of concrete pavement are diamond ground every year.
Benefits
As trucks travel across bumps and dips, they bounce vertically on their suspension resulting in dynamic loading on the roadway. The increased load due to dynamic impact results in higher stresses in the pavement materials and consequently lower road life. By providing an extremely smooth surface, diamond grinding limits dynamic loading.
A potential benefit of diamond grinding may be reduced road noise, depending on the grinding technique used and the surface texture that is left. A longitudinal texture can provide a quieter surface than many transverse textures. A multi-state study on noise and texture on PCC pavements concluded that longitudinal texture concrete pavements are among the quietest pavements for interior and exterior noise. Diamond grinding can also remove faults by leveling the pavement surface, thus eliminating the thumping and slapping sound created by faulted joints.
Enhanced surface texture and skid resistance is another benefit of diamond grinding. The corrugated surface increases surface macrotexture and provides channels for water to displace beneath vehicle tires, reducing hydroplaning potential. Diamond grinding also improves cornering friction, providing directional stability by tire tread-pavement groove interlock.
Diamond grinding has been found to reduce accident rates in some scenarios. The increased macrotexture provides for improved drainage of water at the tire-pavement interface, thus improving wet-weather friction, particularly for vehicles with balding tires. The longitudinal nature of a diamond-ground texture also provides directional stability and reduces hydroplaning, thus contributing to the safety of diamond ground surfaces.
Diamond grinding should be applied to the portion of the pavement where restoration is needed. A highway agency can require grinding only on the truck lanes of a four-lane divided highway, presenting a significant cost advantage.
See also
References
External links
International Grooving & Grinding Association.net
Concrete cut with saw
Concrete
Grinding and lapping | Diamond grinding of pavement | Engineering | 1,129 |
62,529,155 | https://en.wikipedia.org/wiki/Epichlo%C3%AB%20sibirica | Epichloë sibirica is a haploid species in the fungal genus Epichloë.
A systemic and seed-transmissible grass symbiont first described in 2009, Epichloë sibirica is a sister lineage to Epichloë gansuensis and an early branching clade on the Epichloë tree.
Epichloë sibirica is found in Asia, where it has been identified in the grass species Achnatherum sibiricum. Epichloë sibirica is not known to be sexual.
References
sibirica
Fungi described in 2009
Fungi of Asia
Fungus species | Epichloë sibirica | Biology | 123 |
66,187,030 | https://en.wikipedia.org/wiki/Arthur%20von%20Abramson | Arthur von Abramson (born 3 March 1854) was an Imperial Russian civil engineer.
He was born to a Jewish family in Odessa, and was educated at the city's gymnasium. He studied mathematics at the University of Odessa, but left to take a course in civil engineering at the Zurich Polytechnikum, from which he was graduated in 1876. Returning to Russia in 1879, von Abramson passed the state examination at the Russian Imperial Institute of Roads and Communications, and was appointed one of the directors of the Russian state railway at Kiev. He devised, built, and managed the sewer system of Kiev, and constructed the street-railroad of that city. In 1881 he founded and became editor-in-chief of a technical monthly, Inzhener ('The Engineer'). He was appointed president of the local sewer company and director of the Kiev city railroad.
Publications
Published in English as
References
1854 births
Year of death unknown
ETH Zurich alumni
Civil engineers from the Russian Empire
Editors from the Russian Empire
Odesa Jews
Print editors
Railway civil engineers
People from the Russian Empire in rail transport | Arthur von Abramson | Engineering | 220 |
5,121,058 | https://en.wikipedia.org/wiki/Grob%20fragmentation | A Grob fragmentation is an elimination reaction that breaks a neutral aliphatic chain into three fragments: a positive ion spanning atoms 1 and 2 (the "electrofuge"), an unsaturated neutral fragment spanning positions 3 and 4, and a negative ion (the "nucleofuge") comprising the rest of the chain.
For example, the positive ion may be a carbenium, carbonium or acylium ion; the neutral fragment could be an alkene, alkyne, or imine; and the negative fragment could be a tosyl or hydroxyl ion:
The reaction is named for the Swiss chemist .
Alternately, atom 1 could begin as an anion, in which case it becomes neutral rather than going from neutral to cationic.
History
An early instance of fragmentation is the dehydration of di(tert-butyl)methanol yielding 2-methyl-2-butene and isobutene, a reaction described in 1933 by Frank C. Whitmore. This reaction proceeds by formation of a secondary carbocation followed by a rearrangement reaction to a more stable tertiary carbocation and elimination of a t-butyl cation:
Albert Eschenmoser in 1952 investigated the base catalysed fragmentation of certain beta hydroxy ketones:
The original work by Grob (1955) concerns the formation of 1,5-hexadiene from cis- or trans-1,4-dibromocyclohexane by sodium metal:
According to reviewers Prantz and Mulzer (2010), the name Grob fragmentation was chosen "in more or less glaring disregard of the earlier contributions".
Reaction mechanism
The reaction mechanism varies with reactant and reaction conditions with the fragmentation taking place in a concerted reaction or taking place in two steps with a carbocationic intermediate when the nucleofuge leaves first or taking place in two steps with an anionic intermediate when the electrofuge leaves first. The carbanionic pathway is more common and is facilitated by the stability of the cation formed and the leaving group ability of the nucleofuge. With cyclic substrates, the preferred geometry of elimination is for the sigma bond that drives out the leaving group to being anti to it, analogous to the conformational orientation in the E2 mechanism of elimination reactions.
Examples
Thapsigargin from Wieland–Miescher ketone
An example of a Grob-like fragmentation in organic synthesis is the expansion of the Wieland–Miescher ketone to thapsigargin:
In this reaction, diastereoselective reduction of the ketone 1 with sodium borohydride yields alcohol 2, which is functionalized to the mesylate 3 with mesyl chloride in pyridine. The selectivity of the initial reduction of ketone 1 is a result of borohyride approaching from the bottom face to avoid steric clash with the axial methyl group. Then reduction of the enone to allyl alcohol 4 with tri-tert-butoxyaluminium hydride in tetrahydrofuran followed by hydroboration with borane in THF yields the borane 5 (only one substituent displayed for clarity). The diastereoselectivity of the hydroboration is a result of two factors: avoidance of the axial methyl group as well as axial hydride addition to avoid a twist-boat conformation in the transition state. The Grob fragmentation to 6 takes place with sodium methoxide in methanol at reflux. A methoxide group attacks the boron atom giving a borate complex which fragments. As each boron atom can hold three substrate molecules (R), the ultimate boron byproduct is trimethyl borate. As seen in 6, the mesylate being in the equatorial position allows its sigma star orbital to align ideally with the sigma bond drawn, allowing for the correct olefin geometry seen in 7.
Another example is an epoxy alcohol fragmentation reaction as part of the Holton Taxol total synthesis.
aza-Grob fragmentation
3-aza-Grob fragmentation is variation which takes place when an electrofuge and nucleofuge are situated at positions 1 and 5 on a secondary or tertiary amine chain with the nitrogen at the 3 position. The reaction products are an electrofugal fragment, an imine, and a nucleofugal fragment (such as an alcohol).
3-aza-Grob fragmentation can proceed with several different nucleofuges. The reaction mechanism has been reported to begin with the reduction of an ether protected amide to form a secondary alcohol. Fragmentation then takes place in a concerted step to form the reaction products.
The scope of the reaction has been found to cover THF and tetrahydrothiophene protecting groups using various hydride agents.
See also
Eschenmoser fragmentation
Wharton reaction
References
Elimination reactions
Name reactions | Grob fragmentation | Chemistry | 1,034 |
25,115,903 | https://en.wikipedia.org/wiki/ANSI%20C12.10 | ANSI C12.10 is the ANSI American National Standard for Physical Aspects of Watt-hour Meters.
This standard covers the physical aspects of both detachable and bottom-connected watt-hour meters and associated registers. These include ratings, internal wiring arrangements, pertinent dimensions, markings and other general specifications.
This standard includes references to latest version of ANSI C12.1 and ANSI C12.20 for performance requirements. Dimensions and other relevant specifications have been coordinated with ANSIC12.7-2005 American National Standard Requirements for Watthour Meters Sockets.
References
See also
Refer to the Programming with C by E. Balagurusami.
Refer to the latest versions of ANSI C12.1 and ANSI C12.20 for performance requirements.
Electrical standards
ANSI C12 | ANSI C12.10 | Physics | 164 |
11,548,142 | https://en.wikipedia.org/wiki/Sirosporium%20diffusum | Sirosporium diffusum is an ascomycete fungus that is a plant pathogen, infecting pecan.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal tree pathogens and diseases
Pecan tree diseases
Enigmatic Ascomycota taxa
Fungus species | Sirosporium diffusum | Biology | 61 |
3,776,986 | https://en.wikipedia.org/wiki/Umpolung | In organic chemistry, umpolung () or polarity inversion is the chemical modification of a functional group with the aim of the reversal of polarity of that group. This modification allows secondary reactions of this functional group that would otherwise not be possible. The concept was introduced by D. Seebach (hence the German word for reversed polarity) and E.J. Corey. Polarity analysis during retrosynthetic analysis tells a chemist when umpolung tactics are required to synthesize a target molecule.
Introduction
The vast majority of important organic molecules contain heteroatoms, which polarize carbon skeletons by virtue of their electronegativity. Therefore, in standard organic reactions, the majority of new bonds are formed between atoms of opposite polarity. This can be considered to be the "normal" mode of reactivity.
One consequence of this natural polarization of molecules is that 1,3- and 1,5- heteroatom substituted carbon skeletons are extremely easy to synthesize (Aldol reaction, Claisen condensation, Michael reaction, Claisen rearrangement, Diels-Alder reaction), whereas 1,2-, 1,4-, and 1,6- heteroatom substitution patterns are more difficult to access via "normal" reactivity. It is therefore important to understand and develop methods to induce umpolung in organic reactions.
Examples
The simplest method of obtaining 1,2-, 1,4-, and 1,6- heteroatom substitution patterns is to start with them. Biochemical and industrial processes can provide inexpensive sources of chemicals that have normally inaccessible substitution patterns. For example, amino acids, oxalic acid, succinic acid, adipic acid, tartaric acid, and glucose are abundant and provide nonroutine substitution patterns.
Cyanide-type umpolung
The canonical umpolung reagent is the cyanide ion. The cyanide ion is unusual in that a carbon triply bonded to a nitrogen would be expected to have a (+) polarity due to the higher electronegativity of the nitrogen atom. Yet, the negative charge of the cyanide ion is localized on the carbon, giving it a (-) formal charge. This chemical ambivalence results in umpolung in many reactions where cyanide is involved.
For example, cyanide is a key catalyst in the benzoin condensation, a classical example of polarity inversion.
The net result of the benzoin reaction is that a bond has been formed between two carbons that are normally electrophiles.
N-heterocyclic carbenes
N-heterocyclic carbenes are similar to cyanide in reactivity. Like cyanide, they have an unusual chemical ambivalence, which allows them to trigger umpolung in reactions where they are involved. The carbene has six electrons - two each in the carbon-nitrogen single bonds, two in its sp2-hybridized orbital, and an empty p-orbital. The sp2 lone pair acts as an electron donor, whereas the empty p-orbital is capable as acting as an electron acceptor.
In this example, the β-carbon of the α,β-unsaturated ester 1 formally acts as a nucleophile, whereas normally it would be expected to be a Michael acceptor.
This carbene reacts with the α,β-unsaturated ester 1 at the β-position forming the intermediate enolate 2. Through tautomerization 2b can displace the terminal bromine atom to 3. An elimination reaction regenerates the carbene and releases the product 4.
For comparison: in the Baylis-Hillman reaction the same electrophilic β-carbon atom is attacked by a reagent but resulting in the activation of the α-position of the enone as the nucleophile.
Thiamine pyrophosphate
Biological processes can employ cyanide-like umpolung reactivity without having to rely on the toxic cyanide ion. Thiamine (which itself is an N-heterocyclic carbene) pyrophosphate (TPP) serves a functionally identical role. The thiazolium ring in TPP is deprotonated within the hydrophobic core of the enzyme, resulting in a carbene which is capable of umpolung.
Enzymes which use TPP as a cofactor can catalyze umpolung reactivity, such as the decarboxylation of pyruvate.
In the absence of TPP, the decarboxylation of pyruvate would result in the placement of a negative charge on the carbonyl carbon, which would run counter to the normal polarization of the carbon-oxygen double bond.
3-membered rings
3-membered rings are strained moieties in organic chemistry. When a 3-membered ring contains a heteroatom, such as in an epoxide or in a bromonium intermediate, the three atoms in the ring become polarized. It is impossible to assign (+) and (-) polarities to a 3-membered ring without having two adjacent atoms with the same polarity. Therefore, whenever a polarized 3-membered ring is opened by a nucleophile, umpolung inevitably results . For example, the opening of ethylene oxide with hydroxide leads to ethylene glycol.
Carbonyl umpolung / anion relay chemistry
Dithiane chemistry is a classic example of polarity inversion. This can be observed in the Corey-Seebach reaction.
Ordinarily the oxygen atom in the carbonyl group is more electronegative than the carbon atom and therefore the carbonyl group reacts as an electrophile at carbon. This polarity can be reversed when the carbonyl group is converted into a dithiane or a thioacetal. In synthon terminology the ordinary carbonyl group is an acyl cation and the dithiane is a masked acyl anion.
When the dithiane is derived from an aldehyde such as acetaldehyde the acyl proton can be abstracted by n-butyllithium in THF at low temperatures. The thus generated 2-lithio-1,3-dithiane reacts as a nucleophile in nucleophilic displacement with alkyl halides such as benzyl bromide, with other carbonyl compounds such as cyclohexanone or oxiranes such as phenyl-epoxyethane, shown below. After hydrolysis of the dithiane group the final reaction products are α-alkyl-ketones or α-hydroxy-ketones. A common reagent for dithiane hydrolysis is (bis(trifluoroacetoxy)iodo)benzene.
Dithiane chemistry opens the way to many new chemical transformations. One example is found in so-called anion relay chemistry in which a negative charge of an anionic functional group resulting from one organic reaction is transferred to a different location within the same carbon framework and available for secondary reaction. In this example of a multi-component reaction both formaldehyde (1) and isopropylaldehyde (8) are converted into dithianes 3 and 9 with 1,3-propanedithiol. Sulfide 3 is first silylated by reaction with tert-butyllithium and then trimethylsilyl chloride 4 and then the second acyl proton is removed and reacted with optically active (−)-epichlorohydrin 6 replacing chlorine. This compound serves as the substrate for reaction with the other dithiane 9 to the oxirane ring opening product 10. Under influence of the polar base HMPA, 10 rearranges in a 1,4-Brook rearrangement to the silyl ether 11 reactivating the formaldehyde dithiane group as an anion (hence the anion relay concept). This dithiane group reacts with oxirane 12 to the alcohol 13 and in the final step the sulfide groups are removed with (bis(trifluoroacetoxy)iodo)benzene.
The anion relay chemistry tactic has been applied elegantly in the total synthesis of complex molecules of significant biological activity, such as spongistatin 2 and mandelalide A.
Oxidative bond formation
It is possible to form a bond between two carbons of (-) polarity by using an oxidant such as iodine. In this total synthesis of enterolactone, the 1,4- relationship of oxygen substituents is assembled by the oxidative homocoupling of a carboxylate enolate using iodine as the oxidant.
Amine umpolung
Ordinarily the nitrogen atom in the amine group is reacting as a nucleophile by way of its lone pair. This polarity can be reversed when a primary or secondary amine is substituted with a good leaving group (such as a halogen atom or an alkoxy group). The resulting N-substituted compound can behave as an electrophile at the nitrogen atom and react with a nucleophile as for example in the electrophilic amination of carbanions.
Hydrazone umpolung
Recently, various carbonyls have been turned into organometallic reagent surrogates via hydrazone umpolung by C.-J. Li et al. In the presence of a catalyst, similar to organometallic reagents, hydrazones can undergo nucleophilic additions, conjugate additions, and transition-metal catalyzed cross-couplings with various electrophiles to form new C-C bonds.
References
External links
Organic chemistry | Umpolung | Chemistry | 2,056 |
76,196,925 | https://en.wikipedia.org/wiki/Brigitte%20Zanda | Brigitte Zanda (born July 29, 1958) is a French meteoriticist, astrophysicist, and cosmochemist. She is an associate professor at the National Museum of Natural History (MNHN) in Paris, affiliated with the Institut de minéralogie, de physique des matériaux et de cosmochimie.
As a teacher-researcher, she specializes in primitive meteorites: chondrites. In 2019–2020, she served as the vice president of the Meteoritical Society. Additionally, she is the co-director of the FRIPON observation network and the coordinator-manager of the participatory science project Vigie-Ciel.
Biography
Brigitte Zanda was a student at the École normale supérieure de jeunes filles from 1978 to 1982. She continued her education at the École nationale supérieure des mines de Paris where she was a research fellow from 1982 to 1984. From 1984 to 1989, she worked as a research engineer at the Institut d'astrophysique de Paris, affiliated with the CNRS.
She defended her doctoral thesis in fundamental geochemistry, entitled Les réactions nucléaires induites par le rayonnement cosmique dans les météorites de fer, at the University of Paris VII in 1988, under the supervision of Jean Audouze. A year later, Brigitte Zanda became an associate professor at the National Museum of Natural History, where she was responsible for the conservation of the national meteorite collection.
As part of her professional activities at the Museum, Brigitte Zanda is involved in the dissemination of scientific culture. She also works in the scientific direction of the Astronomy Festival of Fleurance and is responsible for the scientific organization of the AstroNomades festival. She also co-pilots the ANR FRIPON project and directs the / project "Vigie-Ciel".
Publications
Le fer de Dieu : histoire de la météorite de Chinguetti, with Théodore Monod, Actes Sud, 2008, 152 pages. ISBN 978-2742775521.
Low temperature magnetic transition of chromite in ordinary chondrites, J. Gattacceca et al., 2011.
Honors
The asteroid discovered by S.J. Bus on March 2, 1981, initially called "1981 EO42", was named "(5047) Zanda" in her honor.
References
See also
(5047) Zanda
External links
Official website
"Zanda, Brigitte (1958-....) | Canal U"
Brigitte Zanda. Radio France
Brigittte Zanda. entities.oclc.org.
Living people
French astrophysicists
French geochemists
Cosmologists
French science communicators
École Normale Supérieure alumni
Paris Diderot University alumni
Discoverers of asteroids
1958 births
Geochemists
French women astronomers
Mines Paris - PSL alumni | Brigitte Zanda | Chemistry | 596 |
29,181,635 | https://en.wikipedia.org/wiki/Inocybe%20praetervisa | Inocybe praetervisa is a small, yellow and brown mushroom in the family Inocybaceae, distinguished from other members of the genus by its unusual spores and bulb. The unusual spores led to the species being named the type species of the now-abandoned genus Astrosporina; recent studies have shown that such a genus could not exist, as the species with the defining traits do not form a monophyletic group. However, it is a part of several clades within the genus Inocybe. I. praetervisa grows on the ground in woodland, favouring beech trees, and is found in Europe, North America and Asia. It is inedible and probably poisonous due to the presence of muscarine. The ingestion of muscarine can lead to SLUDGE syndrome, and could potentially lead to death due to respiratory failure.
Taxonomy and naming
Inocybe praetervisa was first described by Lucien Quélet in the first volume of Giacomo Bresadola's 1883 publication Fungi tridentini. The species was moved to the genus Astrosporina by Joseph Schröter in 1889, but this was rejected, and the name Astrosporina praetervisa is now considered an obligate synonym. Astrosporina praetervisa was the type species of the no longer recognised genus. The specific epithet praetervisa comes from the Latin word meaning "overlooked".
Within the genus Inocybe, I. praetervisa has been placed in the subgenus Inocybe. Mycologist Rolf Singer places the species in the section Marginatae; mycologist Thom Kuyper considers Marginatae a supersection, and includes I. praetervisa along with I. abietis, I. calospora and I. godeyi. Phylogenetics has shown that, in addition to the large clade of subgenus Inocybe, I. praetervisa forms a clade with I. calospora, I. lanuginosa and I. leptophylla. The species are similar in that all four have basidiospores with small nodules; it was this feature that defined the genus Astrosporina, with then A. praetervisa as its type species. However, when phylogenetic analysis later concluded that nodulose-spored Inocybe species do not form a monophyletic group, the name Astrosporina was deemed inappropriate at a generic level. But it may be considered useful at a lower level to refer to the clade of the four Inocybe species. Of those four, I. praetervisa is most closely related to I. calospora, with which it forms a smaller and closer clade. A different study also found the close relationship between I. praetervisa and I. calospora; it also named I. teraturgus as a part of the clade containing I. praetervisa, I. calospora, I. lanuginosa and I. leptophylla.
Description
Inocybe praetervisa has a bell-shaped (later expanding) cap of in diameter, which is a yellowish-brown colour. It is fibrous, and splits from the margin (which curves inwards) to the centre. The stem is from in height, and from thick. It is white, maturing to a pale straw-yellow, and the whole stem is farinaceous, meaning it is covered in particles resembling meal. The stem has a distinct bulb at the base, which is moderately marginate, and lacks a ring. The flesh is white, and discolours to yellowish in the stem. The gills are initially whitish, but later become a clay-brown with toothed, white edges. They are adnexed, meaning they connect to the stem by only part of their depth, and are crowded closely together.
Microscopic features
Inocybe praetervisa leaves a clay-brown spore print, while the spores themselves are rectangular with a large number of "distinct, angular knobs". In size, the spores measure between in length by between in width. Inocybe praetervisa has both pleuro- and cheilocystidia which are relatively spindle-shaped with apical encrustation. The cystidia have hyaline or pale yellow walls.
Similar species
The species can be differentiated from the similar I. cookei by its "irregular, lumpy spores". It is also similar to I. rimosa, but differs in the presence of a bulb. Another species that can be differentiated by the lack of a bulb is I. numerosigibba.
Habitat and distribution
Inocybe praetervisa is an ectomycorrhizal species, and is found on the ground in mixed, deciduous or even coniferous woodland. It typically favours beech. Mushrooms grow solitarily or in "trooping groups" in late summer and throughout autumn, though it is not commonly encountered species. It is found in Europe, Asia and North America.
Edibility and toxicity
The species has a mild, indistinct taste, and a faint smell of flour. Mycologist Roger Phillips describes its edibility as "suspect", recommending that it be avoided, and notes that it is possible that the species is poisonous; most species of Inocybe have been shown to contain poisonous chemicals. Mycologist Ian Robert Hall lists the mushroom as containing the poisonous compound muscarine. Consumption of muscarine could lead to a number of physiological effects, including: excess salivation, lacrimation, uncontrollable urination and defecation, gastrointestinal problems and emesis (vomiting); this array of symptoms is also known by the acronym SLUDGE. Other potential effects include a drop in blood pressure, sweating and death due to respiratory failure.
See also
List of Inocybe species
References
praetervisa
Fungi described in 1883
Fungi of Europe
Fungi of North America
Fungi of Asia
Poisonous fungi
Taxa named by Lucien Quélet
Fungus species | Inocybe praetervisa | Biology,Environmental_science | 1,286 |
53,552,010 | https://en.wikipedia.org/wiki/Brachychiton%20sp.%20Ormeau | Brachychiton sp. Ormeau is a rare and endangered rainforest tree found in Queensland, Australia.
Description
A species of tree belonging to the genus Brachychiton, it reaches up to 25 metres in height. The leaves are dropped during the dry season, a time of year the species favours for reproduction, and return as pale to coppery coloured new growth. The flowering period is during September, the profuse display of green to white bell-shaped flowers appearing at the terminus of the branches; the width of each flower is around 10 mm. Fruiting pods appear from January to February, these are 3 cm long, brown, and boat-shaped. During the later stages of growth the trunk begins to form an exaggerated bottle shape, and the leaves alter from a deeply lobed shape, divided from five to nine times, to a glossy and often elliptical leaf 12 to 20 cm long.
The tree is capable of attaining a great age, over 120 years being possible. Sexual maturity is reached after around twenty years.
Distribution and range
The Ormeau bottle trees are noticeably restricted in range, extending over a range of only 6.5 km2 and occurring in very low population densities. The largest stand, regarded as the most viable population, is reported to consist of 131 plants. Another two reproductive populations have been found in separate locations nearby but each contains fewer than ten trees; other individuals occur as non-seeding outliers within this total population of 161 trees.
Conservation
The main population occurs within an 'environmental park', the Wongawallan Conservation Area in the rural suburb of Wongawallan, Queensland, where it is afforded some protection from threatening factors. The small groups outside this area are located on a lease for proposed quarries. The federal government has named this tree as one of thirty plant species to be given the highest priority for protection from extinction, and that its status be improved by the year 2020. The major threats identified are habitat loss, fire, insect and weed infestation and the low genetic diversity of those populations that remain.
References
Ormeau
Malvales of Australia
Trees of Australia
Flora of Queensland
Undescribed plant species | Brachychiton sp. Ormeau | Biology | 439 |
36,554,275 | https://en.wikipedia.org/wiki/3%20Equulei | 3 Equulei is a single star located in the small northern constellation of Equuleus. It is faintly visible to the naked eye at an apparent visual magnitude of 5.6. Based upon an annual parallax shift of 4.24 mas, 3 Equulei is roughly distant from Earth, give or take an 80 light-year margin of error. At that distance, the apparent brightness of the star is diminished by 0.15 in visual magnitude because of extinction from interstellar gas and dust.
3 Equulei has been referred to in some sources as ζ (Zeta) Equulei, although it was not given that designation by Bayer.
Properties
3 Equulei is an evolved giant star with a stellar classification of K5 III. The measured angular diameter of this star, after correction for limb darkening, is . At the estimated distance of 770 light-years, this yields a physical size of about 63 times the radius of the Sun. It is radiating an estimated 949 times the luminosity of the Sun from this expanded outer envelope at an effective temperature of 3,893 K. At this heat, it shines with the orange-hued glow of a K-type star.
References
External links
http://frostydrew.org/stars.dc/star/id-126518/pss-obsy/
Equuleus
K-type giants
Equulei, Zeta
Equulei, 03
Durchmusterung objects
200644
8066
104031 | 3 Equulei | Astronomy | 316 |
23,387,624 | https://en.wikipedia.org/wiki/Cellulose%20fiber | Cellulose fibers () are fibers made with ethers or esters of cellulose, which can be obtained from the bark, wood or leaves of plants, or from other plant-based material. In addition to cellulose, the fibers may also contain hemicellulose and lignin, with different percentages of these components altering the mechanical properties of the fibers.
The main applications of cellulose fibers are in the textile industry, as chemical filters, and as fiber-reinforcement composites, due to their similar properties to engineered fibers, being another option for biocomposites and polymer composites.
History
Cellulose was discovered in 1838 by the French chemist Anselme Payen, who isolated it from plant matter and determined its chemical formula. Cellulose was used to produce the first successful thermoplastic polymer, celluloid, by Hyatt Manufacturing Company in 1870. Production of rayon ("artificial silk") from cellulose began in the 1890s, and cellophane was invented in 1912. In 1893, Arthur D. Little of Boston, invented yet another cellulosic product, acetate, and developed it as a film. The first commercial textile uses for acetate in fiber form were developed by the Celanese Company in 1924. Hermann Staudinger determined the polymer structure of cellulose in 1920. The compound was first chemically synthesized (without the use of any biologically derived enzymes) in 1992, by Kobayashi and Shoda.
Cellulose structure
Cellulose is a polymer made of repeating glucose molecules attached end to end. A cellulose molecule may be from several hundred to over 10,000 glucose units long. Cellulose is similar in form to complex carbohydrates like starch and glycogen. These polysaccharides are also made from multiple subunits of glucose. The difference between cellulose and other complex carbohydrate molecules is how the glucose molecules are linked together. In addition, cellulose is a straight chain polymer, and each cellulose molecule is long and rod-like. This differs from starch, which is a coiled molecule. A result of these differences in structure is that, compared to starch and other carbohydrates, cellulose cannot be broken down into its glucose subunits by any enzymes produced by animals.
Types
Natural cellulose fibers
Natural cellulose fibers are still recognizable as being from a part of the original plant because they are only processed as much as needed to clean the fibers for use. For example, cotton fibers look like the soft fluffy cotton balls that they come from. Linen fibers look like the strong fibrous strands of the flax plant. All "natural" fibers go through a process where they are separated from the parts of the plant that are not used for the end product, usually through harvesting, separating from chaff, scouring, etc. The presence of linear chains of thousands of glucose units linked together allows a great deal of hydrogen bonding between OH groups on adjacent chains, causing them to pack closely into cellulose fibers. As a result, cellulose exhibits little interaction with water or any other solvent. Cotton and wood, for example, are completely insoluble in water and have considerable mechanical strength. Since cellulose does not have a helical structure like amylose, it does not bind to iodine to form a colored product.
Manufactured cellulose fibers
Manufactured cellulose fibers come from plants that are processed into a pulp and then extruded in the same ways that synthetic fibers like polyester or nylon are made. Rayon or viscose is one of the most common "manufactured" cellulose fibers, and it can be made from wood pulp. Fibers may also be produced from Laminaria hyperborea nozzle-pressurized gyration and wet spinning, along with resonant acoustic mixing.
Structure and properties
Natural fibers are composed by microfibrils of cellulose in a matrix of hemicellulose and lignin. This type of structure and the chemical composition of them is responsible for the mechanical properties that can be observed. Because the natural fibers make hydrogen bonds between the long chains, they have the necessary stiffness and strength.
Chemical composition
The major constituents of natural fibers (lignocelluloses) are cellulose, hemicellulose, lignin, pectin and ash. The percentage of each component varies for each different type of fiber, however, generally, are around 60-80% cellulose, 5–20% lignin, and 20% of moisture, besides hemicellulose and a small percent of residual chemical components. The properties of the fiber change depending on the amount of each component, since the hemicellulose is responsible for the moisture absorption, bio- and thermal degradation whereas lignin ensures thermal stability but is responsible for the UV degradation. The chemical composition of common natural fibers are shown below; these vary depending on whether the fiber is a bast fiber (obtained from the bark), a core fiber (obtained from the wood), or a leaf fiber (obtained from the leaves).
Mechanical properties
Cellulose fiber response to mechanical stresses change depending on fiber type and chemical structure present. Information about main mechanical properties are shown in the chart below and can be compared to properties of commonly used fibers such glass fiber, aramid fiber, and carbon fiber.
Surface and interfacial properties
Hydrophilicity, roughness and surface charge determine the interaction of cellulose fibers with an aqueous environment. Already in 1950, the charge at the interface between cotton as the predominant cellulose fiber and an aqueous surrounding was investigated by the streaming potential method to assess the surface zeta potential. Due to the high swelling propensity of lignocellulosic fibers, a correlation between the zeta potential and the water uptake capability has been observed. Even for the use of waste fibers as a reinforcement in composite materials, sized fibers have been probed by an aqueous test solution. A review on the electrokinetic properties of natural fibers including cellulose and lignocellulosic fibers is found in the Handbook of Natural Fibers.
Applications
Composite materials
Composite materials are a class of material most often made by the combination of a fiber with a binder material (matrix). This combination mixes the properties of the fiber with the matrix to create a new material that may be stronger than the fiber alone. When combined with polymers, cellulose fibers are used to create some fiber-reinforced materials such as biocomposites and fiber-reinforced plastics. The table displays different polymer matrices and the cellulose fibers they are often mixed with.
Since macroscopic characteristics of fibers influence the behavior of the resulting composite, the following physical and mechanical properties are of particular interest:
Dimensions: The relationship between the length and diameter of the fibers is a determining factor in the transfer of efforts to the matrix. Additionally, the irregular cross-section and fibrillated appearance of plant fibers helps anchor them within a fragile matrix.
Void volume and water absorption: Fibers are fairly porous with a large volume of internal voids. As a result, when the fibers are immersed in the binding material, they absorb a large amount of matrix. High absorption can cause fiber shrinkage and matrix swelling. However, a high void volume contributes to reduced weight, increased acoustic absorption, and low thermal conductivity of the final composite material.
Tensile strength: Similar, on average, to the polypropylene's fibers.
Elastic modulus: Cellulosic fibers have a low modulus of elasticity. This determines its use in building components working in post-cracked stage, with high energy absorption and resistance to dynamic forces.
Textile
In the textile industry regenerated cellulose is used as fibers such as rayon, (including modal, and the more recently developed Lyocell). Cellulose fibers are manufactured from dissolving pulp. Cellulose-based fibers are of two types, regenerated or pure cellulose such as from the cupro-ammonium process and modified cellulose such as the cellulose acetates.
The first artificial fiber, commercially promoted as artificial silk, became known as viscose around 1894, and finally rayon in 1924. A similar product known as cellulose acetate was discovered in 1865. Rayon and acetate are both artificial fibers, but not fully synthetic, being a product of a chemically digested feedstock comprising natural wood. They are also not an artificial construction of silk, which is a fibrous polymer of animal proteins. Although these artificial fibers were discovered in the mid-nineteenth century, successful modern manufacture began much later.
Filtration
The cellulose fibers infiltration/filter aid applications can provide a protective layer to filter elements as powdered cellulose, besides promoting improved throughput and clarity. As ashless and non-abrasive filtration, make cleanup effortless after the filtering process without damage in pumps or valves. They effectively filter metallic impurities and absorb up to 100% of emulsified oil and boiler condensates. In general, cellulose fibers in filtration applications can greatly improve filtration performance when used as a primary or remedial precoat in the following ways:
Bridging gaps in the filter septum and small mechanical leaks in the gaskets and leaf seats
Improving the stability of the filter-aid cake to make it more resistant to pressure bumps and interruptions
Creating a more uniform precoat with no cracks for more effective filtration surface area
Improving cake release and reducing cleaning requirements
Preventing fine particulate bleed-through
Precoating easily and rapidly and reducing soluble contamination
Comparison with other fibers
In comparison with engineered fibers, cellulose fibers have important advantages as low density, low cost, they can be recyclable, and are biodegradable. Due to its advantages cellulose fibers can be used as a substituent for glass fibers in composites materials.
Environmental issues
What is often marketed as "bamboo fiber" is actually not the fibers that grow in their natural form from the bamboo plants, but instead a highly processed bamboo pulp that is extruded as fibers. Although the process is not as environmentally friendly as "bamboo fiber" appears, planting & harvesting bamboo for fiber can, in certain cases, be more sustainable and environmentally friendly than harvesting slower growing trees and clearing existing forest habitats for timber plantations.
See also
Fiber modification
References
External links
Dissolving of Cellulosics
Cellulose
Fibers
Materials
Textiles | Cellulose fiber | Physics | 2,182 |
2,173,845 | https://en.wikipedia.org/wiki/Omamori | are Japanese amulets commonly sold at Shinto shrines and Buddhist temples, dedicated to particular Shinto as well as Buddhist figures and are said to provide various forms of luck and protection.
Origin and usage
The word means 'protection', with being the (honorific) form of the word. Originally made from paper or wood, modern amulets are small items usually kept inside a brocade bag and may contain a prayer, religious inscription of invocation. are available at both Shinto shrines and Buddhist temples with few exceptions and are available for sale, regardless of one's religious affiliation.
are then made sacred through the use of ritual, and are said to contain (spiritual offshoots) in a Shinto context or (manifestations) in a Buddhist context.
While are intended for temple tourists' personal use, they are mainly viewed as a donation to the temple or shrine the person is visiting. Visitors often give as a gift to another person as a physical form of well-wishing.
Design and function
are usually covered with brocaded silk and enclose paper or pieces of wood with prayers written on them, which are supposed to bring good luck to the bearer on particular occasions, tasks, or ordeals. are also used to ward off bad luck and are often spotted on bags, hung on cellphone straps, in cars, etc.
have changed over the years from being made mostly of paper and/or wood to being made out of a wide variety of materials (i.e. bumper decals, bicycle reflectors, credit cards, etc.). Modern commercialism has also taken over a small part of the production of . Usually this happens when more popular shrines and temples cannot keep up with the high demand for certain charms. They then turn to factories to manufacture the . However, priests have been known to complain about the quality and authenticity of the products made by factories.
According to Yanagita Kunio (1969):
Usage
may provide general blessings and protection, or may have a specific focus such as:
: traffic safety-protection for drivers and travelers of all sorts
: avoidance of evil
: open luck, better fortune
: education and passing examinations—for students and scholars
: prosperity in business—success in business and matters of money
: acquisition of a mate and marriage—available for singles and couples to ensure love and marriage
: protection for pregnant women for a healthy pregnancy and easy delivery
: safety (well-being) of one's family, peace and prosperity in the household
Customarily, are not opened in order to avoid losing their protective benefits. They are instead carried on one's person, or tied to something like a backpack or a purse. It is not necessary, but amulets are customarily replaced once a year to ward off bad luck from the previous year. Old amulets are usually returned to the same shrine or temple they were purchased at so they can be disposed of properly. Amulets are commonly returned on or slightly after the Japanese New Year so the visitor has a fresh start for the New Year with a new .
Old traditionally should not be disposed of, but burned, as a sign of respect to the deity that assisted the person throughout the year.
If a shrine or temple visitor cannot find an that meets their need, they can request for a priest to have one made. If enough people request for this same type of , the temple or shrine may start producing them for everyday availability.
Modern commercial uses
There are modern commercial versions of that are typically not spiritual in nature and are not issued by a shrine or temple. It has become popular for stores in Japan to feature generic with popular characters such as Mickey Mouse, Hello Kitty, Snoopy, Kewpie, etc.
See also
References
Further reading
External links
Omamori.com
Amulets
Talismans
Shinto
Buddhist religious objects
Religious objects
Shinto religious objects
Superstitions of Japan
Eastern esotericism
Japanese words and phrases | Omamori | Physics | 789 |
60,359 | https://en.wikipedia.org/wiki/Benthos | Benthos (), also known as benthon, is the community of organisms that live on, in, or near the bottom of a sea, river, lake, or stream, also known as the benthic zone. This community lives in or near marine or freshwater sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.
Many organisms adapted to deep-water pressure cannot survive in the upper parts of the water column. The pressure difference can be very significant (approximately one atmosphere for every 10 metres of water depth).
Because light is absorbed before it can reach deep ocean water, the energy source for deep benthic ecosystems is often organic matter from higher up in the water column that drifts down to the depths. This dead and decaying matter sustains the benthic food chain; most organisms in the benthic zone are scavengers or detritivores.
The term benthos, coined by Haeckel in 1891, comes from the Greek noun 'depth of the sea'. Benthos is used in freshwater biology to refer to organisms at the bottom of freshwater bodies of water, such as lakes, rivers, and streams. There is also a redundant synonym, Benton.
Overview
Compared to the relatively featureless pelagic zone, the benthic zone offers physically diverse habitats. There is a huge range in how much light and warmth is available, and in the depth of water or extent of intertidal immersion. The seafloor varies widely in the types of sediment it offers. Burrowing animals can find protection and food in soft, loose sediments such as mud, clay and sand. Sessile species such as oysters and barnacles can attach themselves securely to hard, rocky substrates. As adults they can remain at the same site, shaping depressions and crevices where mobile animals find refuge. This greater diversity in benthic habitats has resulted in a higher diversity of benthic species. The number of benthic animal species exceeds one million. This far exceeds the number of pelagic animal species (about 5000 larger zooplankton species, 22,000 pelagic fish species and 110 marine mammal species).
By size
Macrobenthos
Macrobenthos, prefix , comprises the larger, visible to the naked eye, benthic organisms greater than about 1 mm in size. In shallow waters, seagrass meadows, coral reefs and kelp forests provide particularly rich habitats for macrobenthos. Some examples are polychaete worms, bivalves, echinoderms, sea anemones, corals, sponges, sea squirts, turbellarians and larger crustaceans such as crabs, lobsters and cumaceans.
Meiobenthos
Meiobenthos, prefix , comprises tiny benthic organisms that are less than about 1 mm but greater than about 0.1 mm in size. Some examples are nematodes, foraminiferans, tardigrades, gastrotriches and smaller crustaceans such as copepods and ostracodes.
Microbenthos
Microbenthos, prefix from the Greek mikrós 'small', comprises microscopic benthic organisms that are less than about 0.1 mm in size. Some examples are bacteria, diatoms, ciliates, amoeba, flagellates.
Marine microbenthos are microorganisms that live in the benthic zone of the ocean – that live near or on the seafloor, or within or on surface seafloor sediments. Microbenthos are found everywhere on or about the seafloor of continental shelves, as well as in deeper waters, with greater diversity in or on seafloor sediments. In photic zones benthic diatoms dominate as photosynthetic organisms. In intertidal zones changing tides strongly control opportunities for microbenthos.
Both foraminifera and diatoms have planktonic and benthic forms, that is, they can drift in the water column or live on sediment at the bottom of the ocean. Regardless of form, their shells sink to the seafloor after they die. These shells are widely used as climate proxies. The chemical composition of the shells are a consequence of the chemical composition of the ocean at the time the shells were formed. Past water temperatures can be also be inferred from the ratios of stable oxygen isotopes in the shells, since lighter isotopes evaporate more readily in warmer water leaving the heavier isotopes in the shells. Information about past climates can be inferred further from the abundance of forams and diatoms, since they tend to be more abundant in warm water.The sudden extinction event which killed the dinosaurs 66 million years ago also rendered extinct three-quarters of all other animal and plant species. However, deep-sea benthic forams flourished in the aftermath. In 2020 it was reported that researchers have examined the chemical composition of thousands of samples of these benthic forams and used their findings to build the most detailed climate record of Earth ever.
Some endoliths have extremely long lives. In 2013 researchers reported evidence of endoliths in the ocean floor, perhaps millions of years old, with a generation time of 10,000 years. These are slowly metabolizing and not in a dormant state. Some Actinomycetota found in Siberia are estimated to be half a million years old.
By type
Zoobenthos
Zoobenthos, prefix , animals belonging to the benthos. Examples include polychaete worms, starfish and anemones.
Phytobenthos
Phytobenthos, prefix , plants belonging to the benthos, mainly benthic diatoms and macroalgae (seaweed).
By location
Endobenthos
Endobenthos (or endobenthic), prefix , lives buried, or burrowing in the sediment, often in the oxygenated top layer, e.g., a sea pen or a sand dollar.
Epibenthos
Epibenthos (or epibenthic), prefix , lives on top of the sediments, e.g., sea cucumber or a sea snail.
Hyperbenthos
Hyperbenthos (or hyperbenthic), prefix , lives just above the sediment, e.g., a rock cod.
Food sources
The main food sources for the benthos are phytoplankton and organic detrital matter. In coastal locations, organic run off from land provides an additional food source. Meiofauna and bacteria consume and recycle organic matter in the sediments, playing an important role in returning nitrate and phosphate to the pelagic.
The depth of water, temperature and salinity, and type of local substrate all affect what benthos is present. In coastal waters and other places where light reaches the bottom, benthic photosynthesizing diatoms can proliferate. Filter feeders, such as sponges and bivalves, dominate hard, sandy bottoms. Deposit feeders, such as polychaetes, populate softer bottoms. Fish, such as dragonets, as well as sea stars, snails, cephalopods, and crustaceans are important predators and scavengers.
Benthic organisms, such as sea stars, oysters, clams, sea cucumbers, brittle stars and sea anemones, play an important role as a food source for fish, such as the California sheephead, and humans.
Ecological role
Benthos as bioindicators
Benthic macro-invertebrates play a critical role in aquatic ecosystems. These organisms can be used to indicate the presence, concentration, and effect of water pollutants in the aquatic environment. Some water contaminants—such as nutrients, chemicals from surface runoff, and metals—settle in the sediment of river beds, where many benthos reside. Benthos are highly sensitive to contamination, so their close proximity to high pollutant concentrations make these organisms ideal for studying water contamination.
Benthos can be used as bioindicators of water pollution through ecological population assessments or through analyzing biomarkers. In ecological population assessments, a relative value of water pollution can be detected. Observing the number and diversity of macro-invertebrates in a waterbody can indicate the pollution level. In highly contaminated waters, a reduced number of organisms and only pollution-tolerant species will be found. In biomarker assessments, quantitative data can be collected on the amount of and direct effect of specific pollutants in a waterbody. The biochemical response of macro-invertebrates' internal tissues can be studied extensively in the laboratory. The concentration of a chemical can cause many changes, including changing feeding behaviors, inflammation, and genetic damage, effects that can be detected outside of the stream environment. Biomarker analysis is important for mitigating the negative impacts of water pollution because it can detect water pollution before it has a noticeable ecological effect on benthos populations.
Carbon processing
Organic matter produced in the sunlit layer of the ocean and delivered to the sediments is either consumed by organisms or buried. The organic matter consumed by organisms is used to synthesize biomass (i.e. growth) converted to carbon dioxide through respiration, or returned to the sediment as faeces. This cycle can occur many times before either all organic matter is used up or eventually buried. This process is known as the biological pump.
In the long-term or at steady-state, i.e., the biomass of benthic organisms does not change, the benthic community can be considered a black box diverting organic matter into either metabolites or the geosphere (burial). The macrobenthos also indirectly impacts carbon cycling on the seafloor through bioturbation.
Threats
Benthos are negatively impacted by fishing, pollution and litter, deep-sea mining, oil and gas activities, tourism, shipping, invasive species, climate change (and its impacts such as ocean acidification, ocean warming and changes to ocean circulation) and construction such as coastal development, undersea cables, and wind farm construction.
See also
Aphotic zone
Benthic fish
Benthopelagic fish
Bioirrigation
Bottom feeder
Deep sea
Deep sea communities
Deep sea mining
Demersal fish
Epibenthic sled
Intertidal ecology
Littoral
Neritic zone
Nekton
Plankton
Pelagic zone
Photic zone
Profundal zone
Sediment Profile Imagery (SPI)
Stream bed
Notes
References
"Benthos". (2008) Encyclopædia Britannica. (Retrieved May 15, 2008, from Encyclopædia Britannica Online.)
Ryan, Paddy (2007) "Benthic communities" Te Ara - the Encyclopædia of New Zealand, updated 21 September 2007.
Yip, Maricela and Madl, Pierre (1999) "Benthos" University of Salzburg.
External links
"Benthos"
Marine organisms
Ecology terminology
Oceanographical terminology | Benthos | Biology | 2,248 |
48,551,016 | https://en.wikipedia.org/wiki/Cantharellus%20guyanensis | Cantharellus guyanensis is a tropical South American species of mushroom-forming fungus in the chanterelle genus (Cantharellus), first described by Camille Montagne from French Guiana in 1854.
It has since also been found in Guyana, Suriname, Venezuela, and Brazil. The fruit bodies have a bright orange cap colour and occur in medium- to large-sized troops. C. guyanensis seems to prefer sand-rich soil and forms ectomycorrhiza with a putatively wide range of host trees and shrubs including Coccoloba, Guapira, and Neea. Its congeners Cantharellus aurantioconspicuus, C. amazonensis, and C. protectus, all described from Brazil, are similar species.
Although edible, C. guyanensis seems to be shunned by the Patamona people of Guyana who however use several other mushroom species occurring in their land. Known as "chanterelle de Guyane" in French, the species is presumably eaten in French Guiana.
References
External links
Tropical Fungi – Cantharellus guyanensis
guyanensis
Fungi described in 1854
Fungus species | Cantharellus guyanensis | Biology | 241 |
306,766 | https://en.wikipedia.org/wiki/GROMACS | GROMACS is a molecular dynamics package mainly designed for simulations of proteins, lipids, and nucleic acids. It was originally developed in the Biophysical Chemistry department of University of Groningen, and is now maintained by contributors in universities and research centers worldwide. GROMACS is one of the fastest and most popular software packages available, and can run on central processing units (CPUs) and graphics processing units (GPUs). It is free, open-source software released under the GNU Lesser General Public License (LGPL) (GPL prior to Version 4.6).
History
The GROMACS project originally began in 1991 at Department of Biophysical Chemistry, University of Groningen, Netherlands (1991–2000). Its name originally derived from this time (GROningen MAchine for Chemical Simulations) although currently GROMACS is not an abbreviation for anything, as little active development has taken place in Groningen in recent decades. The original goal was to construct a dedicated parallel computer system for molecular simulations, based on a ring architecture (since superseded by modern hardware designs). The molecular dynamics specific routines were rewritten in the programming language C from the Fortran 77-based program GROMOS, which had been developed in the same group.
Since 2001, GROMACS is developed by the GROMACS development teams at the Royal Institute of Technology and Uppsala University, Sweden.
Features
GROMACS is operated via the command-line interface, and can use files for input and output. It provides calculation progress and estimated time of arrival (ETA) feedback, a trajectory viewer, and an extensive library for trajectory analysis. In addition, support for different force fields makes GROMACS very flexible. It can be executed in parallel, using Message Passing Interface (MPI) or threads. It contains a script to convert molecular coordinates from Protein Data Bank (PDB) files into the formats it uses internally. Once a configuration file for the simulation of several molecules (possibly including solvent) has been created, the simulation run (which can be time-consuming) produces a trajectory file, describing the movements of the atoms over time. That file can then be analyzed or visualized with several supplied tools.
GROMACS has had GPU offload support since Version 4.5, originally limited to Nvidia GPUs. GPU support has been expanded and improved over the years, and, in Version 2023, GROMACS has CUDA, OpenCL, and SYCL backends for running on GPUs of AMD, Apple, Intel, and Nvidia, often with great acceleration compared to CPU.
Easter eggs
, GROMACS' source code contains approximately 400 alternative backronyms to GROMACS as jokes among the developers and biochemistry researchers. These include "Gromacs Runs On Most of All Computer Systems", "Gromacs Runs One Microsecond At Cannonball Speeds", "Good ROcking Metal Altar for Chronical Sinner", "Working on GRowing Old MAkes el Chrono Sweat", and "Great Red Owns Many ACres of Sand". They are randomly selected to possibly appear in GROMACS's output stream. In one instance, such an bacronym, "Giving Russians Opium May Alter Current Situation", caused offense.
Applications
Under a non-GPL license, GROMACS is widely used in the Folding@home distributed computing project for simulations of protein folding, where it is the base code for the project's largest and most regularly used series of calculation cores. EvoGrid, a distributed computing project to evolve artificial life, also employs GROMACS.
See also
References
External links
GROMACS forums
Tutorials: official tutorials, unofficial tutorial by Justin Lemkul, unofficial tutorial by Wes Barnett, usage on the bwHPC Clusters in Germany
Specific versions: GROMACS on GPUs by NVIDIA, binaries of GROMACS 4.6.5 for Windows / Cygwin
Free software programmed in C
Molecular dynamics software | GROMACS | Chemistry | 814 |
23,927,668 | https://en.wikipedia.org/wiki/Quick%20coupler | Quick couplers (also called quick hitches) are used with construction machines to allow the rapid change of working tools or buckets and attachments on the machine. They remove the need to use hammers to manually drive out and insert the mounting pins for attachments. They also bring with them additional safety risks that must be overcome by careful design and manufacture, and proper use.
Description
Quick couplers are devices installed at the outer end of the work equipment of various types of construction and earth-moving machines. They facilitate the rapid exchange of working tools or buckets. Quick couplers are most common on hydraulic excavators and compact excavators and on the backhoe equipment of backhoe loaders, but are also installed on telescopic handlers, wheel loaders (loading shovels), skid-steer loaders and the loader equipment of backhoe-loaders. They are also occasionally installed on attachments installed on agricultural tractors.
Quick couplers do not normally have a specific function themselves in that they do not carry out handling or digging operations, but when installed on a machine they become a part of the overall system. They are usually mounted on the machine by means of the pins that would otherwise be the mountings for the bucket or attachment.
This article concentrates on quick couplers installed on excavators and similar equipment.
Types
There are many variations in the design of quick couplers. The initial divergence is between those that can pick up any of a range of buckets and attachments by clamping onto the mounting pins for the attachment (known as "pin grabbers" or "pin couplers") and those that work only with buckets and attachments designed to suit that quick coupler (known as "dedicated"). The claimed advantage of pin-grabbers is flexibility in use in that a machine owner can use a variety of buckets and attachments without changing the quick coupler or buying an adaptor. The claimed advantages of dedicated couplers depend on their individual design but often include better performance and smaller size.
Operation
The method of operation (the picking up and releasing of buckets and attachments) causes the next divergence in design. The types can be described as manual, semi-automatic, and automatic.
Manual The operation of this type is done, usually by the use of tools, at the coupler itself. The operator needs to leave the operator's station (usually the cab) to go to the end of the work equipment in order to effect the release of a bucket or attachment, and to do the same in order to attach the next bucket or attachment to be used.
Semi-automatic With this type the hydraulic system of the machine is used to operate the main attachment mechanism but the manual operation of a safety device is necessary at the coupler itself to ensure that the bucket or attachment is safely locked onto the coupler. The safety device is intended to prevent the release of the bucket or attachment in the event of the failure of the hydraulic system, or other major failure of the attachment mechanism. The safety device is most commonly a pin that must be inserted to prevent one of the components in the quick coupler moving to release the bucket or attachment but some designs require the manual operation of a lever on the quick coupler.
Automatic This type use the hydraulic system of the machine to operate the main attachment mechanism and have an internal safety device. As with semi-automatic systems the safety device is designed to prevent the release of the bucket or attachment in the event of a failure of the hydraulic system.
Within the above three categories there are many further divergences in operating principles and detail designs. There are many competing claims relating to the safety and performance benefits and demerits of each design.
Safety issues
Fatalities have occurred due to buckets being accidentally released from work equipment during operation. Released buckets have hit bystanders causing fatal injuries. These have been reported in most detail in the UK, but there are reports of fatalities in Australia, the Republic of Ireland and the USA.
The causes of the fatal accidents are not always the same and the views of safety authorities in different countries differ on how to reduce risk. In the UK the Health and Safety Executive (HSE) analysed the accident data and concluded that all of the known fatalities were caused by the operator not inserting the safety pin in semi-automatic couplers. Even without the safety pin inserted the buckets would not have been released unless there had been a failure of some part of the mechanism, or some error in operation by the operator. The HSE concluded that the most effective way to reduce the risk of further accidents was for semi-automatic couplers to be withdrawn from sale. The suppliers of these couplers agreed to this voluntarily so semi-automatic couplers were withdrawn from sale in the UK by around October 2008.
Safety authorities in other countries have taken a different approach. In Australia the authorities took the view that the problems were caused by designs of quick couplers that did not incorporate a safety pin. That is, they believe that semi-automatics are fundamentally safe. The Australian standard for quick couplers published by Standards Australia, AS 4774 - 2008 therefore does not exclude this design option. It is therefore obvious that the views of the safety authorities of the UK and Australia on what constitutes a safe design are very divergent.
In the UK some major construction contractors have written their own specifications for quick couplers allowed on sites under their control. That is, they have pursued site safety via a procurement policy. An alternative approach has been put forward by the Strategic Forum Plant Safety Group. A working party under this group has drawn up a best practice guide that has been endorsed, inter alia, by the HSE. This provides an alternative route to site safety: adhering to best practice in the use of quick couplers.
Market
The market for quick couplers is mainly supplied by a large number of small and medium-sized enterprises. Many of the manufacturers of quick couplers are small, flexible and innovative, leading to the wide variation in design concepts. Many Original Equipment Manufacturers (OEMs) of construction equipment market a range of quick couplers. Some of these are designed and manufactured by the OEM but more often they are the products of one of the quick coupler manufacturers branded by the OEM and sold through the OEM's distribution chain or installed by the OEM in their factory.
In addition to the supply route from the OEMs many distributors of construction machinery will install quick couplers onto machines before delivery at the request of a customer. Quick coupler manufacturers will also sell direct to end-users and usually complete the installation as part of the sale.
Development of international safety standards
A European standard in place since 1996 gives some guidance on the safety of quick couplers (EN474-1). However, this standard is unclear in many aspects leading to uncertainty as to whether semi-automatic couplers comply with it or not. Because of this the UK government launched a "safeguard action" under the Machinery Safety Directive (98/37/EC) challenging the validity of the standard and demanding that it be improved. The European Committee for Standardization (CEN) have therefore undertaken to revise the relevant section of the standard.
Because of the divergence in design concepts and in opinions on how to manage the associated risks the International Organization for Standardization (ISO) has undertaken to draft an International Standard on the safety of quick couplers. This project is being undertaken by Technical Committee 127 (ISO TC/127). A Working Group was set up to draft the standard, which will be reviewed internationally through normal ISO procedures and will be published as ISO 13031. This work will probably be completed in 2013. The intention in Europe is that, subject to the standard being suitable, the ISO standard would then be adopted as the standard for Europe.
References
Construction equipment | Quick coupler | Engineering | 1,602 |
8,968,929 | https://en.wikipedia.org/wiki/Wave%20equation%20analysis | Wave equation analysis is a numerical method of analysis for the behavior of driven foundation piles. It predicts the pile capacity versus blow count relationship (bearing graph) and pile driving stress. The model mathematically represents the pile driving hammer and all its accessories (ram, cap, and cap block), as well as the pile, as a series of lumped masses and springs in a one-dimensional analysis. The soil response for each pile segment is modeled as viscoelastic-plastic. The method was first developed in the 1950s by E.A. Smith of the Raymond Pile Driving Company.
Wave equation analysis of piles has seen many improvements since the 1950s such as including a thermodynamic diesel hammer model and residual stress. Commercial software packages (such as AllWave-PDP and GRLWEAP) are now available to perform the analysis.
One of the principal uses of this method is the performance of a driveability analysis to select the parameters for safe pile installation, including recommendations on cushion stiffness, hammer stroke and other driving system parameters that optimize blow counts and pile stresses during pile driving. For example, when a soft or hard layer causes excessive stresses or unacceptable blow counts.
References
Smith, E.A.L. (1960) Pile-Driving Analysis by the Wave Equation. Journal of the Engineering Mechanics Division, Proceedings of the American Society of Civil Engineers. Vol. 86, No. EM 4, August.
External links
The Wave Equation Page for Piling
Deep foundations
Soil mechanics | Wave equation analysis | Physics | 303 |
641,995 | https://en.wikipedia.org/wiki/Asymptotic%20analysis | In mathematical analysis, asymptotic analysis, also known as asymptotics, is a method of describing limiting behavior.
As an illustration, suppose that we are interested in the properties of a function as becomes very large. If , then as becomes very large, the term becomes insignificant compared to . The function is said to be "asymptotically equivalent to , as ". This is often written symbolically as , which is read as " is asymptotic to ".
An example of an important asymptotic result is the prime number theorem. Let denote the prime-counting function (which is not directly related to the constant pi), i.e. is the number of prime numbers that are less than or equal to . Then the theorem states that
Asymptotic analysis is commonly used in computer science as part of the analysis of algorithms and is often expressed there in terms of big O notation.
Definition
Formally, given functions and , we define a binary relation
if and only if
The symbol is the tilde. The relation is an equivalence relation on the set of functions of ; the functions and are said to be asymptotically equivalent. The domain of and can be any set for which the limit is defined: e.g. real numbers, complex numbers, positive integers.
The same notation is also used for other ways of passing to a limit: e.g. , , . The way of passing to the limit is often not stated explicitly, if it is clear from the context.
Although the above definition is common in the literature, it is problematic if is zero infinitely often as goes to the limiting value. For that reason, some authors use an alternative definition. The alternative definition, in little-o notation, is that if and only if
This definition is equivalent to the prior definition if is not zero in some neighbourhood of the limiting value.
Properties
If and , then, under some mild conditions, the following hold:
, for every real
if
Such properties allow asymptotically equivalent functions to be freely exchanged in many algebraic expressions.
Examples of asymptotic formulas
Factorial —this is Stirling's approximation
Partition function For a positive integer n, the partition function, p(n), gives the number of ways of writing the integer n as a sum of positive integers, where the order of addends is not considered.
Airy function The Airy function, Ai(x), is a solution of the differential equation ; it has many applications in physics.
Hankel functions
Asymptotic expansion
An asymptotic expansion of a function is in practice an expression of that function in terms of a series, the partial sums of which do not necessarily converge, but such that taking any initial partial sum provides an asymptotic formula for . The idea is that successive terms provide an increasingly accurate description of the order of growth of .
In symbols, it means we have but also and for each fixed k. In view of the definition of the symbol, the last equation means in the little o notation, i.e., is much smaller than
The relation takes its full meaning if for all k, which means the form an asymptotic scale. In that case, some authors may abusively write to denote the statement One should however be careful that this is not a standard use of the symbol, and that it does not correspond to the definition given in .
In the present situation, this relation actually follows from combining steps k and k−1; by subtracting from one gets i.e.
In case the asymptotic expansion does not converge, for any particular value of the argument there will be a particular partial sum which provides the best approximation and adding additional terms will decrease the accuracy. This optimal partial sum will usually have more terms as the argument approaches the limit value.
Examples of asymptotic expansions
Gamma function
Exponential integral
Error function where is the double factorial.
Worked example
Asymptotic expansions often occur when an ordinary series is used in a formal expression that forces the taking of values outside of its domain of convergence. For example, we might start with the ordinary series
The expression on the left is valid on the entire complex plane , while the right hand side converges only for . Multiplying by and integrating both sides yields
The integral on the left hand side can be expressed in terms of the exponential integral. The integral on the right hand side, after the substitution , may be recognized as the gamma function. Evaluating both, one obtains the asymptotic expansion
Here, the right hand side is clearly not convergent for any non-zero value of t. However, by keeping t small, and truncating the series on the right to a finite number of terms, one may obtain a fairly good approximation to the value of . Substituting and noting that results in the asymptotic expansion given earlier in this article.
Asymptotic distribution
In mathematical statistics, an asymptotic distribution is a hypothetical distribution that is in a sense the "limiting" distribution of a sequence of distributions. A distribution is an ordered set of random variables for , for some positive integer . An asymptotic distribution allows to range without bound, that is, is infinite.
A special case of an asymptotic distribution is when the late entries go to zero—that is, the go to 0 as goes to infinity. Some instances of "asymptotic distribution" refer only to this special case.
This is based on the notion of an asymptotic function which cleanly approaches a constant value (the asymptote) as the independent variable goes to infinity; "clean" in this sense meaning that for any desired closeness epsilon there is some value of the independent variable after which the function never differs from the constant by more than epsilon.
An asymptote is a straight line that a curve approaches but never meets or crosses. Informally, one may speak of the curve meeting the asymptote "at infinity" although this is not a precise definition. In the equation y becomes arbitrarily small in magnitude as x increases.
Applications
Asymptotic analysis is used in several mathematical sciences. In statistics, asymptotic theory provides limiting approximations of the probability distribution of sample statistics, such as the likelihood ratio statistic and the expected value of the deviance. Asymptotic theory does not provide a method of evaluating the finite-sample distributions of sample statistics, however. Non-asymptotic bounds are provided by methods of approximation theory.
Examples of applications are the following.
In applied mathematics, asymptotic analysis is used to build numerical methods to approximate equation solutions.
In mathematical statistics and probability theory, asymptotics are used in analysis of long-run or large-sample behaviour of random variables and estimators.
In computer science in the analysis of algorithms, considering the performance of algorithms.
The behavior of physical systems, an example being statistical mechanics.
In accident analysis when identifying the causation of crash through count modeling with large number of crash counts in a given time and space.
Asymptotic analysis is a key tool for exploring the ordinary and partial differential equations which arise in the mathematical modelling of real-world phenomena. An illustrative example is the derivation of the boundary layer equations from the full Navier-Stokes equations governing fluid flow. In many cases, the asymptotic expansion is in power of a small parameter, : in the boundary layer case, this is the nondimensional ratio of the boundary layer thickness to a typical length scale of the problem. Indeed, applications of asymptotic analysis in mathematical modelling often center around a nondimensional parameter which has been shown, or assumed, to be small through a consideration of the scales of the problem at hand.
Asymptotic expansions typically arise in the approximation of certain integrals (Laplace's method, saddle-point method, method of steepest descent) or in the approximation of probability distributions (Edgeworth series). The Feynman graphs in quantum field theory are another example of asymptotic expansions which often do not converge.
Asymptotic versus Numerical Analysis
De Bruijn illustrates the use of asymptotics in the following dialog between Dr. N.A., a Numerical Analyst, and Dr. A.A., an Asymptotic Analyst:
N.A.: I want to evaluate my function for large values of , with a relative error of at most 1%.
A.A.: .
N.A.: I am sorry, I don't understand.
A.A.:
N.A.: But my value of is only 100.
A.A.: Why did you not say so? My evaluations give
N.A.: This is no news to me. I know already that .
A.A.: I can gain a little on some of my estimates. Now I find that
N.A.: I asked for 1%, not for 20%.
A.A.: It is almost the best thing I possibly can get. Why don't you take larger values of ?
N.A.: !!! I think it's better to ask my electronic computing machine.
Machine: f(100) = 0.01137 42259 34008 67153
A.A.: Haven't I told you so? My estimate of 20% was not far off from the 14% of the real error.
N.A.: !!! . . . !
Some days later, Miss N.A. wants to know the value of f(1000), but her machine would take a month of computation to give the answer. She returns to her Asymptotic Colleague, and gets a fully satisfactory reply.
See also
Notes
References
External links
Asymptotic Analysis —home page of the journal, which is published by IOS Press
A paper on time series analysis using asymptotic distribution
Mathematical series | Asymptotic analysis | Mathematics | 2,049 |
9,703,456 | https://en.wikipedia.org/wiki/Nacolomab%20tafenatox | Nacolomab tafenatox is a mouse monoclonal antibody. The antibody itself, nacolomab, is fused with enterotoxin A from Staphylococcus aureus (which is reflected by 'tafenatox' in the drug's name).
See also
Naptumomab estafenatox, a drug with a similar chemical structure and mechanism
References
Monoclonal antibodies for tumors
Antibody-drug conjugates | Nacolomab tafenatox | Biology | 96 |
3,337,942 | https://en.wikipedia.org/wiki/FIRST%20Robotics%20Competition | FIRST Robotics Competition (FRC) is an international high school robotics competition. Each year, teams of high school students, coaches, and mentors work during a six-week period to build robots capable of competing in that year's game that weigh up to . Robots complete tasks such as scoring balls into goals, hanging on bars, placing objects in predetermined locations, and balancing robots on various field elements. The game, along with the required set of tasks, changes annually. While teams are given a kit of a standard set of parts during the annual Kickoff, they are also allowed and encouraged to buy or fabricate specialized parts. FIRST Robotics Competition is one of five robotics competition programs organized by FIRST, the other four being FIRST LEGO League Discover, FIRST LEGO League Explore, FIRST LEGO League Challenge, and FIRST Tech Challenge.
The culture of FIRST Robotics Competition is built around two values. "Gracious Professionalism" embraces the competition inherent in the program but rejects trash talk and chest-thumping, instead embracing empathy and respect for other teams. "Coopertition" emphasizes that teams can cooperate and compete at the same time. The goal of the program is to inspire students to be science and technology leaders.
2024 was the 33rd year of the competition. 3,468 teams, including more than 86,700 students and 27,700 mentors from 28 countries, built robots. The 2024 season included 62 Regional Competitions, 98 District Qualifying Competitions, and 11 District Championships. In 2024, over 600 teams won slots to attend the FIRST Championship event, where they competed in a tournament. In addition to on-field competition, teams and team members competed for awards recognizing entrepreneurship, creativity, engineering, industrial design, safety, controls, media, quality, and exemplifying the core values of the program. As a result of COVID-19, the amount of active teams decreased during the 2021 season; however, numbers began to increase during the 2022 season and onward.
As of 2024, there were 3,468 high school teams with approximately 86,700 high schoolers across 28 countries competing.
Most teams reside in the United States, with Canada, Turkey, Mexico, Israel, Brazil, China, and Australia contributing significant numbers of teams.
History
FIRST was founded in 1989 by American inventor and entrepreneur Dean Kamen, with inspiration and assistance from physicist and MIT professor emeritus Woodie Flowers. Kamen was disappointed with the number of kids—particularly women and minorities—who did not consider science and technology careers and decided to do something about it. As an inventor, he looked for activities that captured the enthusiasm of students and decided that combining the excitement of sports competition with science and technology had the potential to inspire students.
Distilling what sports had done right into a recipe for engaging young people, Kamen says, turned out to be relatively straightforward. "It's after school, not in school. It's aspirational, not required," he explained to me.
"You don't get quizzes and tests, you go into competitions and get trophies and letters. You don't have teachers, you have coaches. You nurture, you don't judge. You create teamwork between all the participants. We justify sports for teamwork but why, when we do it in the classroom, do we call it cheating?"
Most of all, it was a nonjudgmental space, where in contrast science and math in traditional educational settings had been soured with embarrassment and uncertainty.
Kamen has stated that FIRST is the invention he feels most proud of and predicts that participants will be responsible for significant technological advances in years to come. The first FIRST Robotics Competition season was in 1992 and had one event at a high school gymnasium in New Hampshire. That first competition was relatively small-scale, similar in size to today's FIRST Tech Challenge and Vex Robotics Competition games. Robots relied on a wired connection to receive data from drivers; in the following year, it quickly transitioned to a wireless system.
Teams
3,468 teams from 28 countries competed in the 2024 Crescendo season. Of these, 3,141 are "veteran teams" (meaning they have competed in a previous season), and 327 are "rookie teams" (meaning that 2024 was their first season of competition).
The countries represented are listed below:
Competition
FIRST Championship
The FIRST Championship is the culmination of the FIRST Robotics Competition season, and occurs in late April each year. Roughly 800 teams participated in two Championship events in 2018, held in April in Houston, Texas and Detroit, Michigan. After the 2022 championships concluded FIRST announced that the world championship would take place at a single location, Houston, Texas, for the 2023 and 2024 seasons. This was later updated through 2027.
Media exposure
The PBS documentary "Gearing Up" followed four teams through the 2008 season.
In the television series Dean of Invention, Dean Kamen made appeals promoting FIRST prior to commercial breaks.
In 2008, FRC Team 1114, Simbotics, was featured in an ongoing storyline on the hit Canadian TV drama "Degrassi: Next Generation". Team 1114's 2006-2007 world champion VEX robot made an appearance, as well as their 2008 world champion FRC robot.
During the 2010 FIRST Robotics Competition season, FIRST team 3132, Thunder Down Under, was followed by a Macquarie University student film crew to document the first year of FIRST Robotics Competition in Australia. The crew produced a documentary film called I, Wombot. The film premiered during the 2011 Dungog Film Festival.
A book called The New Cool was written by Neal Bascomb about the story of Team 1717 from Goleta, California as they competed in the 2009 game season. A movie adaptation directed by Michael Bacall is being produced.
The CNN documentary "Don't Fail Me: Education in America", which aired on May 15, 2011, followed three FIRST Robotics Competition teams during the 2011 season. The documentary profiled one student from each team, covering different geographic and socioeconomic levels: Shaan Patel from Team 1403 Cougar Robotics, Maria Castro from Team 842 Falcon Robotics, and Brian Whited from Team 3675 Eagletrons.
On August 14, 2011, ABC aired a special on FIRST called "i.am FIRST: Science is Rock and Roll" that featured many famous musical artists such as The Black Eyed Peas and Willow Smith. will.i.am himself was the executive producer of the special. The program placed a special focus on the FIRST Robotics competition, even though it included segments on the FIRST Tech Challenge, FIRST LEGO League, and FIRST LEGO League Jr.
From 1996 to 1998, the FIRST Championship was covered by ESPN.
For the 2013 Macy's Thanksgiving Day Parade, five FIRST Robotics Competition teams and their robots led the parade, with one robot cutting the ribbon and the others shooting confetti.
In the 2014 movie Transformers: Age of Extinction, a FIRST Robotics Competition Robot built by Team 2468, Team Appreciate, for the 2012 Season was featured in Cade Yeager's garage shooting the foam basketball game pieces from Rebound Rumble.
The 2015 Kickoff was, for the first time, broadcast by NBCUniversal, a subsidiary of Comcast, and was available via OnDemand for the month of January 2015.
In 2016, Christina Li, a member of Team 217, the ThunderChickens, was spotlighted on an episode of Nickelodeon's The Halo Effect entitled "Hello World". A coding camp that Li organized for young girls was featured on the episode, and 217's robot from the 2015 season made an appearance.
The fourth season of The Fosters (2013 TV series) had several episodes featuring characters competing in a regional FIRST Robotics Competition competition, most notably episode 8 "Girl Code".
In June 2018, HBO aired a Real Sports with Bryant Gumbel episode, which in a segment, the correspondent Soledad O'Brien interviewed Dean Kamen about FIRST and FIRST Robotics Competition and then later interviewed students from various FRC teams.
The February 25, 2020 episode of the ABC sitcom Black-ish features recurring character, Jack Johnson, joining a FIRST team—and a cameo by Dean Kamen.
Episode 6 in the second season of the Netflix original series Trinkets featured a FIRST Robotics Competition competition.
On March 18, 2022, Disney+ released a documentary directed by Gillian Jacobs titled "More than Robots", which follows four teams in the 2020 season, leading up to the COVID-19 pandemic.
Notable people
Alumni
Priscilla Chan (Team 69)
Leanne Cushing
Emma Dumont (Team 980)
Imraan Faruque
Dylan Field (Team 675)
Amanda Randles
Employees and volunteers
Joseph Bouchard
Imogen Coe
Michael Dubno
Amber Gell
Marc Hodosh, entrepreneur, chairman of the Boston FIRST Robotics Competition competition
Mark Leon, NASA researcher and Master of Ceremonies for several FIRST Robotics Competition events
David Siegel
Mentors
Amir Abo-Shaeer (Team 1717), teacher and engineer, subject of The New Cool
Emma Dumont (Team 680)
Maor Farid
Patrick Freivald (Team 1551)
Grant Imahara (Team 841), engineer and roboticist, former cast member of MythBusters
Dave Lavery (Team 116), NASA scientist and former member of the FIRST Robotics Competition Game Design Committee
Nic Radford (Team 118)
Nancy Yasecko (Team 233)
Games
Gallery
Notes
References
Sources
Michigan robotics champs off to world finals in St. Louis- Detroit Free Press
FIRST Robotics Competition’s 2011 Regional Season Is Worth a Look - PCWorld
External links
NASA FIRST Robotics Competition site
For Inspiration and Recognition of Science and Technology
Engineering competitions
1992 in robotics
Recurring events established in 1992
1992 establishments in New Hampshire
Student robotics competitions | FIRST Robotics Competition | Technology | 1,984 |
77,568,785 | https://en.wikipedia.org/wiki/List%20of%20Swedish%20counties%20by%20life%20expectancy |
Statistics Sweden
Average values for 5-year periods. By default the table is sorted by 2019-2023.
Data source: Statistics Sweden (SCB).
Maps of division of Sweden into counties and NUTS-2 regions:
AB: Stockholm County
AC: Västerbotten County
BD: Norrbotten County
C: Uppsala County
D: Södermanland County
E: Östergötland County
F: Jönköping County
G: Kronoberg County
H: Kalmar County
I: Gotland County
K: Blekinge County
M: Skåne County
N: Halland County
O: Västra Götaland County
S: Värmland County
T: Örebro County
U: Västmanland County
W: Dalarna County
X: Gävleborg County
Y: Västernorrland County
Z: Jämtland County
Eurostat (2019—2022)
By default, the table is sorted by 2022.
Data source: Eurostat
Global Data Lab (2019–2022)
Data source: Global Data Lab
Charts
See also
List of countries by life expectancy
List of European countries by life expectancy
Counties of Sweden
Demographics of Sweden
References
Health in Sweden
Demographics of Sweden
Sweden, life expectancy
Sweden
Provinces of Sweden
Provinces by life expectancy
Sweden | List of Swedish counties by life expectancy | Biology | 260 |
75,102,643 | https://en.wikipedia.org/wiki/Astronomy%20on%20Mercury | Astronomy on Mercury is the sky as viewed from the planet Mercury. Because Mercury only has a thin atmosphere, the sky will be black.
Sun
Due to the proximity of Mercury to the Sun, Mercury on average receives an energy flux from the Sun that is about 7 times the solar constant, but may reach nearly 11 times at maximum and about 4.5 times at minimum. The Sun will have an angular diameter of 1.733 to 1.142°. From perihelion to aphelion, the size of the Sun increases almost 66%, as does the brightness. This is due to the high eccentricity of Mercury's orbit around the Sun.
Due to tidal locking, three rotations of Mercury, is equal to two revolutions around the Sun. Because of this, the method of plotting the Sun's position at the same time each day would yield only a single point. However, the equation of time can still be calculated for any time of the year, so an analemma can be graphed with this information. The resulting curve is a nearly straight east–west line.
During a Mercurian day, the Sun would be seen rising in the east, move up for a while, stop in the sky, head backwards for a while, and then resume going forwards again. This peculiar movement is due to the orbit of Mercury. If the retrograde motion happens within few hours from sunrise, an observer would see two sunsets and two sunrises, in the same day. The Sun would be seen rising, stopping midway, going back down and setting, rise again, and continue its normal journey. Approximately four (Earth) days before perihelion, the angular speed of Mercury's orbit exactly matches its rotational velocity, so that the Sun's apparent motion stops. At perihelion, Mercury's orbital angular velocity slightly exceeds the rotational velocity, making the Sun appear to go retrograde. Four days after perihelion, the Sun's normal apparent motion resumes.
From the moment the top of the Sun can be seen to the moment someone can see a full circle, a sunrise would take almost 6 hours.
Planets and Stars
Apart from the Sun, Venus would be the brightest celestial body. Venus will be brighter from Mercury, than from Earth. The reason for this is that when Venus is closest to Earth, it is between the Earth and the Sun, so only its night side is seen. Even when Venus is brightest in the Earth's sky, humans see only a narrow crescent. For a Mercurian observer, on the other hand, Venus is closest when it is in opposition to the Sun and is showing its full disk. The apparent magnitude of Venus is as bright as −7.7.
The Earth and the Moon also will be very bright, their apparent magnitudes being about −5 and −1.2, respectively. The maximum apparent distance between the Earth and the Moon is about 15′. Which means that an observer on Mercury could differentiate between Earth and Moon as two separate dots in the sky. The Moon will come closer and closer towards Earth, eventually transiting Earth and moving over to the other side. This movement is because of the revolution of Moon around Earth. It is also possible to observe the Moon undergoing a total lunar eclipse which the MESSENGER spacecraft in orbit around Mercury did for the October 8, 2014 lunar eclipse. All other planets are visible just as they are on Earth, but somewhat less bright at opposition with the difference being most considerable for Mars.
The zodiacal light will be more prominent than it is from Earth. Mercury has a southern pole star, α Pictoris, a magnitude 3.2 star. It is fainter than Earth's Polaris. Omicron Draconis is its north star. Furthermore, the Sun is so bright that it is still impossible to see stars during the daytime, unless the observer is well shielded from sunlight (direct or reflected from the ground).
Solar System portrait
On February 18, 2011, a portrait of the Solar System was published on the MESSENGER website. The mosaic contained 34 images, acquired by the MDIS instrument during November 2010. All the planets were visible with the exception of Uranus and Neptune, due to their vast distances from the Sun. The MESSENGER "family portrait" was intended to be complementary to the Voyager family portrait, which was acquired from the outer Solar System by Voyager 1 on February 14, 1990.
See also
References
Mercury (planet)
Observational astronomy | Astronomy on Mercury | Astronomy | 911 |
1,157,197 | https://en.wikipedia.org/wiki/Redshift%20survey | In astronomy, a redshift survey is a survey of a section of the sky to measure the redshift of astronomical objects: usually galaxies, but sometimes other objects such as galaxy clusters or quasars.
Using Hubble's law, the redshift can be used to estimate the distance of an object from Earth. By combining redshift with angular position data, a redshift survey maps the 3D distribution of matter within a field of the sky. These observations are used to measure detailed statistical properties of the large-scale structure of the universe. In conjunction with observations of early structure in the cosmic microwave background, these results can place strong constraints on cosmological parameters such as the average matter density and the Hubble constant.
Generally the construction of a redshift survey involves two phases: first the selected area of the sky is imaged with a wide-field telescope, then galaxies brighter than a defined limit are selected from the resulting images as non-pointlike objects; optionally, colour selection may also be used to assist discrimination between stars and galaxies. Secondly, the selected galaxies are observed by spectroscopy, most commonly at visible wavelengths, to measure the wavelengths of prominent spectral lines; comparing observed and laboratory wavelengths then gives the redshift for each galaxy.
The Great Wall, a vast conglomeration of galaxies over 500 million light-years wide, provides a dramatic example of a large-scale structure that redshift surveys can detect.
The first systematic redshift survey was the CfA Redshift Survey of around 2,200 galaxies, started in 1977 with the initial data collection completed in 1982. This was later extended to the CfA2 redshift survey of 15,000 galaxies, completed in the early 1990s.
These early redshift surveys were limited in size by taking a spectrum for one galaxy at a time; from the 1990s, the development of fibre-optic spectrographs and multi-slit spectrographs enabled spectra for several hundred galaxies to be observed simultaneously, and much larger redshift surveys became feasible. Notable examples are the 2dF Galaxy Redshift Survey (221,000 redshifts, completed 2002); the Sloan Digital Sky Survey (approximately 1 million redshifts by 2007) and the Galaxy And Mass Assembly survey. At high redshift the largest current surveys are the DEEP2 Redshift Survey and the VIMOS-VLT Deep Survey (VVDS); these have around 50,000 redshifts each, and are mainly focused on galaxy evolution.
ZFOURGE or the FourStar Galaxy Evolution Survey is a large and deep medium-band imaging survey which aims to establish an observational benchmark of galaxy properties at redshift z > 1. The survey is using near-infrared FOURSTAR instrument on the Magellan Telescopes, surveying in all three HST legacy fields: COSMOS, CDFS, and UDS.
Because of the demands on observing time required to obtain spectroscopic redshifts (i.e., redshifts determined directly from spectral features measured at high precision), a common alternative is to use photometric redshifts based on model fits to the brightnesses and colors of objects. Such "photo-z's" can be used in large surveys to estimate the spatial distribution of galaxies and quasars, provided the galaxy types and colors are well understood in a particular redshift range. At present, the errors on photometric redshift measurements are significantly higher than those of spectroscopic redshifts, but future surveys (for example, the LSST) aim to significantly refine the technique.
See also
Baryon acoustic oscillations
Intensity mapping
Large-scale structure of the cosmos
Redshift-space distortions
Galaxy filament
References
External links
Probes of Large Scale Structure
List of galaxy redshift surveys
Physical cosmology
Observational astronomy
Large-scale structure of the cosmos | Redshift survey | Physics,Astronomy | 801 |
612,757 | https://en.wikipedia.org/wiki/Piper%20Alpha | Piper Alpha was an oil platform located in the North Sea about north-east of Aberdeen, Scotland. It was operated by Occidental Petroleum (Caledonia) Limited (OPCAL) and began production in December 1976, initially as an oil-only platform, but later converted to add gas production.
Piper Alpha exploded and collapsed under the effect of sustained gas jet fires in the night between 6 and 7 July 1988, killing 165 of the men on board (30 of whose bodies were never recovered), as well as a further two rescuers. Sixty-one workers escaped and survived. The total insured loss was about £1.7 billion (£ billion in ), making it one of the costliest man-made catastrophes ever. At the time of the disaster, the platform accounted for roughly 10% of North Sea oil and gas production and was the world’s single largest oil producer. The accident is the worst ever offshore oil and gas disaster in terms of lives lost, and comparable only to the Deepwater Horizon disaster in terms of industry impact. The inquiry blamed it on inadequate maintenance and safety procedures by Occidental, though no charges were brought. A separate civil suit resulted in a finding of negligence against two workers who were killed in the accident.
A memorial sculpture is located in the Rose Garden of Hazlehead Park in Aberdeen.
Piper oilfield
Four companies (Occidental Petroleum (UK) Ltd, Getty Oil International (England) Ltd, Allied Chemical (Great Britain) Ltd, and Thomson Scottish Associates Ltd) formed a joint venture and obtained an oil-exploration licence in 1972. They discovered the Piper oilfield located at in January 1973, and began fabrication of the platform, pipelines, and onshore support structures. Oil production started in December 1976, less than four years after discovery (a record rarely beaten ever since), with about of oil per day, later increasing to . Production declined to by 1988.
A large, fixed platform, Piper Alpha was located in the Piper oilfield, around northeast of Aberdeen in of water. Piper Alpha produced crude oil and natural gas from 36 wells. OPCAL built the Flotta oil terminal in the Orkney Islands to receive and process oil from the Piper, Claymore (both operated by OPCAL), and Tartan (Texaco) oilfields, each with its own platform. One diameter main oil pipeline ran from Piper Alpha to Flotta.
The Piper platform was the hub of a network of pipelines connecting it to nearby platforms and to shore. The Tartan field fed oil to Claymore, with the co-mingled oil flowing from Claymore through a short pipeline to join the Piper-Flotta line some to the west of Piper.
Separate diameter gas pipelines were run from the Tartan platform to Piper, and from Piper to the Total-operated manifold compression platform MCP-01 some to the northwest. Another line connected Claymore to Piper, primarily to provide gas from Piper to the Claymore gas lift system. MCP-01 would receive the gas from Piper and Tartan, as well as from the Frigg gas field (through a separate pipeline), and send the resulting stream to St Fergus Gas Terminal through a , 2 × 32-inch pipeline.
The inventory of the pipelines was significant, with the main oil line to Flotta containing around 70,000 tonnes of oil and the three gas lines linking Piper to the surrounding platforms close to 2,000 tonnes of high-pressure gas. The pressure in the Tartan–Piper and Piper–MCP-01 pipelines was around 127 bar.
Construction and layout
Piper Alpha's production facilities were designed by Bechtel in London. The supporting platform jacket, as well as the topside module structures and buildings, were designed by McDermott Hudson. The eight-legged jacket structure was constructed by J. Ray McDermott in Ardersier, Inverness-shire, and Union Industrielle et d'Entreprise in Le Havre, France, with the sections united in Ardersier before being towed out during 1975. The jacket weighed around 14,000 tonnes and was tall, of which a length of was permanently submerged. Four clusters of foundation piles extended a further below the seabed. Topside modules weighing about 10,000 tonnes in aggregate were lifted from a crane ship and installed over the jacket in late 1976.
Piper's hydrocarbon facilities and principal utilities were distributed in four main modules (A, B, C, and D) separated by firewalls and sitting atop the steel jacket. Above the main modules were a drilling derrick, various utilities, the living quarters, flare booms, two pedestal cranes, and the helideck.
For safety reasons, the modules were organized so that the most dangerous platform operations took place far from the personnel areas. However, the conversion from oil to gas broke this safety concept, with the result that sensitive areas were brought together; for example, the gas compression module was next to the control room. The close position of these two areas played a significant role in the accident.
The hydrocarbon inventory actually held within the platform was small in comparison with that contained in the pipelines, standing at around 80 tonnes of process fluids and 160 tonnes of diesel fuel (which was stored in tanks located above module C).
Upgrades and production modes
In 1978, major works were carried out to enable the platform to meet British government gas-conservation requirements, and to avoid waste from the flaring of excess gas. A gas conservation module (GCM) was added, built on top of module B. After this work, Piper Alpha operated in what was known as "phase-2 mode", i.e., using the GCM facility. In phase-2 mode, the GCM would treat the gas obtained in the crude oil separation process, separate condensate (or natural gas liquids, NGL) from it, reinject the condensate in the oil export pipeline to Flotta, and compress the gas for export to the pipeline to MCP-01. From the end of 1980 until July 1988, phase-2 mode was its normal operating state.
In the late 1980s, major construction, maintenance, and upgrade works were planned by Occidental, and by July 1988, the rig was already well into major revamp, with six projects identified, including the change-out of the GCM unit. This meant that the rig was returned to its initial "phase-1 mode", i.e., operating without the GCM unit, only three days before the accident. Despite the complex and demanding work schedule, Occidental made the decision to continue operating the platform in phase-1 mode throughout this period and not to shut it down, as had been originally planned. The planning and controls that were put in place were thought to be adequate. At the time of the accident, Piper weighed around 34,000 tonnes. It continued to export oil at just under per day (or 10% of the entire production of the UK sector of the North Sea, which made it the world’s single largest oil producer) and to export Tartan gas at some per day at standard conditions during this period.
Events on 6 and 7 July 1988
Because the platform was completely destroyed, and many of those involved died, analysis of events can only suggest a possible chain of events based on known facts. Some witnesses to the events question the official timeline.
Preliminary events
At 07:45, 6 July 1988, the permit-to-work forms for the day shift were issued and signed. Of the two condensate pumps, both located in module C, pump B was operating to displace the platform's condensate for transport to the coast, while pump A was due for maintenance. Two permits were issued to that effect, one for a pump overhaul and another for the removal of the pump's pressure safety valve (PSV #504), which was due for recertification. During the day, pump A was electrically and mechanically isolated, but containment was not broken. The PSV, instead, was removed. The open condensate pipe upstream of the PSV was temporarily sealed with a disk cover (a flat metal disc also called a blind flange or blank flange). It was hand-tightened only. Because the work could not be completed by 18:00, the blind flange remained in place. The on-duty engineer filled in information on the PSV removal permit to the effect that pump A was not ready and must not be switched on under any circumstances. However, this information was not provided in the pump overhaul permit.
The night shift started at 18:00 with 62 men running Piper Alpha. As the on-duty custodian was busy, the engineer neglected to inform him of the condition of pump A. Instead, he placed the PSV permit in the control centre and left. This permit disappeared and was not found.
At 19:00 the diesel-driven fire pumps were put under manual control. Like many other offshore platforms, Piper Alpha had an automatic fire-fighting system, driven by both diesel and electric fire pumps. The pumps were designed to suck in large amounts of sea water for firefighting and had automatic controls to start them in case of fire. However, the Piper Alpha procedure adopted by the offshore installation manager (OIM) required manual control of the diesel pumps whenever divers were in the water (as they were for about 12 hours a day during summer) although in reality, the risk was not seen as significant, unless a diver was closer than from any of the four level caged intakes. A recommendation from an earlier audit had suggested that a procedure be developed to keep the pumps in automatic mode if divers were not working in the vicinity of the intakes, as was the practice on the Claymore platform, but this was never implemented.
At 21:45, condensate pump B stopped and could not be restarted. This was likely due to the formation of hydrates and the consequent blockage of gas compression pipework, following problems with the methanol system. The operators were anxious to reinstate condensate pumping capacity. Failure to do so would have meant needing to stop the gas compressors and venting to the flare all the gas that could not be processed.
Around 21:52 a search was made through the documents to determine whether condensate pump A could be started. The permit for pump A overhaul was found but that for its PSV removal was not. The valve was at a distance from the pump, so the permits were stored in different boxes, as they were sorted by location. Because the overhaul had just started on the day, with no equipment removed or containment broken, the operators were under the impression that the pump could be put back in operation quickly and safely. None of those present were aware that a vital part of the machine had been removed. The missing valve was not noticed by anyone, particularly as the blind flange replacing the safety valve was several metres above ground level and obstructed from view.
Explosion in module C and initial reactions
At or shortly before 22:00, gas was reintroduced into pump A, filling it. The loosely fitted flange did not withstand the resulting pressure. Gas audibly leaked out at high pressure, drawing the attention of several men and triggering multiple gas alarms. Before anyone could act, the gas ignited and exploded. The source of ignition is unclear, with the later investigation pointing to hot work, hot surfaces, broken light fittings or an electrostatic spark as potential sources (electrical equipment in the surroundings were rated for hazardous areas). The platform, which originally was built for oil production only, was not of a blast-proof design, so the firewalls were not designed to withstand explosions. The blast blew through the firewalls separating module C from the adjoining modules B and D (the latter of which housed the control room), made up of variously sized panels bolted together. As a result, the control room was almost entirely destroyed. Panels around module B were also dislodged, with one of them rupturing a small condensate pipe, thus creating another fire.
Immediately after the explosion, control room operator Geoff Bollands, who had witnessed the alarms going off in the control room and subsequently survived the blast, activated the rig's emergency stop button before escaping. This closed isolation valves in the wells and sea riser lines and ceased all oil and gas production. Theoretically, the platform would then have been isolated from the flow of oil and gas and the fire contained. The gas pipelines connecting Piper to Tartan and Claymore could only be isolated using separate push buttons, which were not actuated; however, the riser isolation valves probably closed due to loss of power supply in the explosion. (At any rate, the flare continued to burn until 23:30, indicating a leak in the Claymore riser isolation valve.)
The control room of Piper Alpha was abandoned. The rig's design made no allowances for the destruction of the control room, and the platform's organization disintegrated. As the diesel fire pumps had been switched to manual activation, the fire water system could not function properly. Additionally, their vulnerable location in module D, adjacent to the failed division from module C, was impossible to reach for the crew to manually activate them. Electrical power quickly failed too, as cables were routed through vulnerable production areas without redundancy. After the main generator tripped, the emergency generator did not take over. The drilling generator started but subsequently failed. Some battery-run systems remained operational for a while. The emergency lighting failed after briefly remaining functional. The failure of power generation facilities also made the electric fire pumps inoperable. Despite Bollands' activation of the emergency shutdown, no alarms warned workers of the unfolding disaster, as the public announcement and general alarm system had been impaired. Multiple mayday calls were made by radio operator David Kinrade starting at 22:04, before the radio room had to be abandoned at 22:08.
At 22:06 the heat from the flames ruptured crude oil pipework and processing vessels in module B. The released oil ignited and the subsequent pool fire created a black plume of smoke characteristic of oil fires, visible from nearby ships. There is evidence that isolation of the produced oil pipeline was not effective, which may have left a route open for oil flowing into the fire due to the backpressure from the Claymore oil pipeline. The burning oil later dripped onto a lower platform used by the rig for diving operations. The platform floor consisted of steel grates, and under normal circumstances would have allowed the burning oil to drip harmlessly into the sea, but divers on the previous shift had placed rubber matting on the metal grate (likely to cushion their bare feet from the sharp metal grates), allowing the oil to form a burning puddle on the platform. After conferring with Bollands and others while still on the main production deck, lead production operator Robert Vernon and safety officer Robert Carroll donned breathing apparatus and left for the diesel fire pumps in an attempt to start them manually. The pair were never to be seen again.
The OIMs of Tartan and Claymore shortly before 22:20 became aware that an explosion had taken place on Piper Alpha and a fire was raging. However, they both decided not to shut down production and instead await orders to that effect from Aberdeen. By this time, 70 to 80 men had mustered in the canteen, with access to the lifeboats or the helideck made impossible by smoke and fire. This room was becoming increasingly hot and full of smoke. Piper's OIM did not order an evacuation.
Subsequent gas pipeline ruptures and platform collapse
At 22:20, in a case of domino effect, the heat from the burning oil collecting on the diving platform caused the nearby Tartan pipeline to rupture violently. This discharged enormous amounts of highly flammable gas (some 30 tonnes only in the first minute of the release), which immediately ignited into a massive jet fire. The heat and vibrations of the fire were felt by the crews in vessels as far away as from the rig. From that moment on, the platform's destruction was inevitable. This potential for an extreme escalation scenario was known to Occidental; a report commissioned by them in 1986 stated that "the gas pipelines, would take hours to depressurize because of their capacity. This could result in a high pressure gas fire on the cellar deck that would be virtually impossible to fight, and the protection systems would not be effective in providing the cooling needed for the duration of the depressurisation".
The MCP-01 pipeline failed at 22:50 as a result of domino effect, and the ensuing jet fire shot huge flames over into the air. Personnel still left alive were either desperately sheltering in the scorched, smoke-filled accommodation block or leaping from the various deck levels, including the helideck, into the North Sea.
The Claymore gas line ruptured at 23:20, adding even more fuel to the already massive jet fires on board Piper Alpha. At this point the Claymore OIM had received orders from Aberdeen to shut down production, and the gas flowline to Piper with it. He had initiated a pipeline blowdown (depressurization) but this was not yet complete at the moment of the rupture. Tartan's gas pipeline had been shut down around 22:30, with its blowdown commencing around 23:20.
Around 23:45, with critical support structures failing from the intense heat, the platform began to collapse. One of the cranes fell first, followed by the drilling derrick. The generation and utilities module (D) and the fireproofed accommodation block, still occupied by crewmen who had sheltered there, then slipped into the North Sea. By 00:45, 7 July, almost all of Piper Alpha was gone, with only module A still standing.
Rescue operations
Nearby vessels and rescue crafts
Vessels that were close to Piper Alpha at the moment of the first explosion included MSV Tharos, a large semi-submersible firefighting, diving/rescue, and accommodation vessel; standby safety vessel MV Silver Pit, who immediately sent her fast rescue boat towards Piper; Maersk Cutter, which started dousing the drilling floor of Piper with her fire monitors as early as ten minutes after the blast; Lowland Cavalier, which had no monitors but immediately deployed a workboat; and converted supply ship Sandhaven, which was the standby vessel for Santa Fe 135, a semi-submersible drilling rig several miles away, and had her fast rescue craft in the water minutes after she spotted the first fire on Piper Alpha. Other vessels that attended the operation later were Loch Shuna, Maersk Logger and Maersk Leader. Overall, 11 fast rescue crafts (FRC) from nearby vessels were involved in the rescue operations.
Tharos launched her Sikorsky S-76 helicopter at 22:11 but it was unable to land on Piper due to smoke. At 22:23 Tharos received a message from Piper: "People majority in galley area. Tharos come. Gangway. Hoses. Getting bad." She drew alongside Piper Alpha around 22:30 and used her water cannon to cool the platform, which was useful in assisting survivors escape from the pipe deck and helideck. Attempts to deploy her extendable gangway over to Piper were unsuccessful. One survivor who jumped when the Tartan riser failed swam to Tharos and climbed out unaided. When the MCP-01 riser failed, Tharos withdrew to away. The MSV was equipped with a hospital with an offshore medic assisted by diver paramedics from a saturation diving team. A triage and reception area were set up on the vessel's helideck to receive injured casualties.
Silver Pit's FRC was launched within two minutes of the first explosion and rescued the first nine people from the northwest corner within 13 minutes. She rescued a total of 29 people, with Silver Pit herself rescuing a further eight. When the Tartan riser failed Silver Pit withdrew to away. When the MCP-01 riser failed, rope on the deck began to smoulder and the vessel withdrew further away.
Lowland Cavalier deployed a workboat that picked up two people who had fallen from a rope at the northwest corner. When the first gas riser failed, the workboat crew sheltered in the water.
Sandhaven's FRC picked up four men who had climbed down ropes. She returned and picked up two more when the MCP-01 riser failed. At that moment, the craft's propeller got entangled in debris. The boat was engulfed in the fire, throwing the survivors and the three crew into the water. All perished with the exception of coxswain Iain Letham. He was picked up from the sea one hour later with his lifejacket and safety helmet melted by the scorching heat.
Support vessel Maersk Cutter began using her fire monitors ten minutes after the explosion.
Aircraft
A mayday launched by Lowland Cavalier at 22:01 was relayed to a rescue coordination centre, which instructed RAF Kinloss station to scramble a Hawker Siddeley Nimrod maritime patrol aircraft. This was to be sent to the area to act as flying communications platform, handling the signals from helicopters and reporting them back. At 22:22 and 22:28 Sea King helicopters Rescue 137 and Rescue 131 took off from RAF Lossiemouth and RAF Boulmer respectively. Shetland Coastguard helicopter Rescue 117 took off at 22:45. Sea King Rescue 138 left Lossiemouth at 22:51. The Nimrod took off from Kinloss at 22:55 using the designation Rescue 01.
When Rescue 01 was still about from Piper, the aircraft crew radioed the rescue coordination centre that they could already see the fire. Rescue 01 arrived at the scene at 23:27. Three minutes later the first search-and-rescue helicopter, Rescue 137, reached Tharos, followed by the arrival of Rescue 117, Rescue 138 and Rescue 131 at 23:44, 23:48 and 23:53 hours respectively. Tharos requested Rescue 138 to evacuate 12 nonessential personnel to make room for incoming casualties. The helicopter transferred them to nearby Ocean Victory, before returning with paramedics. The search-and-rescue helicopters made unsuccessful sweeps for survivors in the water and ferried injured survivors from rescue vessels to Tharos and to Aberdeen Royal Infirmary.
A civilian Sikorsky S-61 of Bristow Helicopters carrying a medical emergency team arrived at the scene by 1:20 on 7 July. At 2:00 another helicopter landed on Tharos the Offshore Specialist Team from Aberdeen Royal Infirmary, with a significant amount of medical equipment. The last survivors were picked up by Rescue 138 from Tharos at 7:25. By 8:15, 63 personnel (among whom one survivor who subsequently died and the surviving member of the crew of Sandhaven's FRC) had been brought ashore. Aircraft were used to search the area of the platform until the afternoon hours.
Casualties and survivors
At the time of the disaster, 226 people were on the platform; 165 died and 61 survived. Two men from the Sandhaven were also killed in attempts to pick up survivors in a fast rescue boat. Of the 135 deceased whose bodies were recovered, the vast majority died from inhalation of smoke and gas, with only four indicating death from burning, and several others from injury sustained from jumping into the sea. Thirty bodies were never recovered.
Since both the lifeboats and the helideck were impaired by smoke or flames, all the survivors were among those that jumped to the water from various decks or climbed down knotted ropes. Five were the survivors that jumped off the helideck from a height of into the North Sea. Luckily, the sea conditions were calm on the evening of the disaster. The largest number of survivors (37 out of 61) were recovered by MV Silver Pit or her fast rescue boat, whose coxswain James Clark later received the George Medal, as did Iain Letham of the Sandhaven. Others awarded the George Medal were Charles Haffey from Methil, Andrew Kiloh from Aberdeen, and James McNeill from Oban. Sandhaven crewmates Malcolm Storey, from Alness, and Brian Batchelor, from Scunthorpe, were awarded George Medals posthumously.
Aftermath
Controversy exists about whether time was sufficient for a more effective emergency evacuation. Systems critical for emergency management such as the public announcement/general alarm, emergency power, safe haven, and – crucially – the lifeboats, were destroyed or impaired due to poor platform design. Executing the actions described in the emergency response plan became effectively impossible. Additionally, the OIM was perhaps not capable of thinking outside the established procedures and of ordering an improvised evacuation.
It was estimated that the fires had produced flames with a height of about 200 metres and a peak rate of about 100 gigawatts, or three times the total power consumption of the United Kingdom.
Around 670 tonnes of oil were spilled in the accident. On 9 July a slick long and wide was reported. Force 4 conditions, together with dispersant sprayed from a supply vessel, helped disperse it.
Only two downhole safety valves failed to close, and five oil wells were left burning. The fires were eventually extinguished by a team onboard Tharos led by firefighter Red Adair, who had been asked to intervene by Occidental chairman Armand Hammer. A relief well was started on 14 July. The wells were capped by 22 July by fitting new valves on top, which allowed introduction of kill fluids.
The accommodation modules where the majority of those onboard had taken refuge were recovered from the seabed in late 1988. They were transported to Flotta, where they were searched by a team led by twenty officers of Grampian Police and including divers as well as Occidental, Department of Energy and Health and Safety Executive personnel. The bodies of 87 men were found inside. The remains of the platform were toppled into the sea on 28 March 1989.
The total insured loss of the disaster was about £1.7 billion (£ billion in ), making it one of the costliest man-made catastrophes ever. The event had a considerable impact on North Sea oil and gas production. Piper, Tartan, and Claymore were not the only fields impacted, with Scapa, Highlander and Petronella also having to wait up to 13 months before half production was regained. The total deferred production amounted to of oil.
Inquiry and safety recommendations
The Piper Alpha Public Inquiry was set up in November 1988 to establish the cause of the disaster. It was chaired by the Scottish judge William Cullen. A variety of sources of evidence were used, including eyewitness accounts from survivors and crews of nearby vessels, data from nearby platforms, the recovery of the deceased, debris collected from the seabed, documentation available ashore, and accounts from 'back-to-back' personnel who had recently worked on Piper Alpha. Highly unusual for an inquiry of this scope was the fact that the entire scene of the accident had effectively disappeared into the sea. The inquiry decided against the recovery of the process modules from the seabed, due to the time required, the hazards involved, and the low chance that that evidence could actually prove useful for the investigation. The living quarters had, however, been recovered, and this allowed for the collection of key documents to support the investigation.
After 180 days of proceedings extending for 13 months, the report Public Inquiry into the Piper Alpha Disaster (short: Cullen Report) was issued in November 1990. It concluded that the initial condensate leak was the result of maintenance work being carried out simultaneously on a pump and related safety valve. The inquiry was critical of Piper Alpha's operator, Occidental, which was found guilty of having inadequate maintenance and safety procedures, but no criminal charges were ever brought against the company.
The second part of the report made 106 recommendations for changes to North Sea safety procedures:
Thirty-seven recommendations covered procedures for operating equipment, 32 the information of platform personnel, 25 the design of platforms and 12 the information of emergency services.
The responsibility to implement was for 57 with the regulator, 40 for the operators, 8 for the industry as a whole and 1 for stand-by ship owners.
The recommendations led to the enactment of the Offshore Safety Act 1992 and the making of the Offshore Installations (Safety Case) Regulations 1992.
Most significant of these recommendations was that operators were required to present a safety case and that the responsibility for enforcing safety in exploitation operations in the part of the North Sea apportioned to the UK should be moved from the Department of Energy to the Health and Safety Executive, as having both production and safety overseen by the same agency was a conflict of interest.
Civil suit
Occidental and their insurers, Lloyd's of London, paid survivors and families of the dead a total of $220 million in settlements. Later, Lloyd's and Elf Enterprise Caledonia Ltd, successors to Occidental Petroleum, brought civil proceedings against a number of contractor companies who were working on Piper at the time of the accident. Based on the argument that the responsibility for the accident should be shared among the platform operator and the contractors working onboard immediately prior to the accident, Elf was seeking to recover from the defendants a part of the monies paid to the injured and the affected families. Among the companies involved were British Telecommunications, Wood Group, and Stena Offshore.
Giving verdict in what was then the longest civil trial in Scottish history, in 1997 Lord Caplan ruled that two workers who were killed in the explosion, Robert Vernon (who had posthumously received the Queen's Commendation for Bravery) and Terence Sutton, were to blame for the accident. Lord Caplan found that Sutton had failed to tighten the bolts of the blind flange at the suction side of the removed PSV, and that Vernon had put the pump back in operation without checking its status first. Vernon was employed by Occidental and Sutton by contractor Score (UK) Ltd. The finding against Vernon and Sutton was controversial among the families of the victims.
Insurance claims
The disaster led to insurance claims of around US$1.4 billion, making it at that time the largest insured man-made catastrophe. The insurance and reinsurance claims process revealed serious weaknesses in the way insurers at Lloyd's of London and elsewhere kept track of their potential exposures and led to their procedures being reformed.
One of the 1997 rulings by Lord Caplan was that, albeit in principle contractors were obliged to indemnify Elf, Elf's insurers could not claim back monies from the defendant contractors, because Elf had already largely been indemnified by Lloyd's. Elf and Lloyd's appealed this finding in Scotland to the Inner House of the Court of Session, which decided in their favour in December 1999. Subsequently, the contractors appealed the decision to the House of Lords in London in November 2001, but their appeal was rejected. As a result, Elf and their insurers were able to recoup £136 million with accrued interest.
Legacy
The accident is the world's worst offshore oil and gas disaster in terms of lives lost. Only the 2010 Deepwater Horizon tragedy has caused a comparable impact in the industry.
Survivors and relatives of those who died went on to form the Piper Alpha Families and Survivors' Association, which campaigns on North Sea safety issues. A lasting effect of the Piper Alpha disaster was the establishment of the Offshore Industry Liaison Committee, the trade union for oil and gas rig workers. The union, while still in the form of an unofficial committee drawn from different North Sea rigs, organized large strikes in the summers of 1989 and 1990.
Piper Bravo was installed in 1992 to replace Alpha and commenced production in February 1993. A wreck buoy marking Alpha's remains was installed and lies approximately from Bravo.
Beginning in 1998, one month after the 10th anniversary, professor David Alexander, director of the Aberdeen Centre for Trauma Research at Robert Gordon University carried out a study into the long-term psychological and social effects of Piper Alpha. He managed to find 36 survivors who agreed to give interviews or complete questionnaires. Almost all of this group reported psychological problems. More than 70% of those interviewed reported psychological and behavioural symptoms of post-traumatic stress disorder. Twenty-eight (or 78%) said they had difficulty in finding employment following the disaster; some offshore employers apparently regarded Piper Alpha survivors as "Jonahs" – bringers of bad luck, who would not be welcome on other rigs and platforms. The family members of the dead and surviving victims also reported various psychological and social problems. Alexander also stated, "some of these lads are stronger than before Piper. They've learned things about themselves, changed their values, some relationships became stronger. People realised they have strengths they didn't know they had. There was a lot of heroism took place."
In 2013, on the 25th anniversary of the tragedy, trade association Oil and Gas UK organized a three-day conference in Aberdeen to reflect on lessons learned from Piper Alpha and industry safety issues in general.
In process safety
The Piper Alpha disaster and the Cullen Report are milestones in the development of process safety. Its effects on the offshore oil and gas industry can be compared with those the Flixborough disaster had on the onshore chemical and petroleum process industry in the 1970s. The Cullen Report put a strong emphasis on the importance of a robust safety management system (SMS). The requirement for a safety management system to be in place was introduced in British legislation in the wake of Piper Alpha. Elements of process safety management that failed on Piper Alpha included:
Permit-to-work, and in particular the mechanism of permit handover. The whole accident chain of events commenced due to the attempt to start-up a pump which was actually under maintenance.
Company audits, which did not pick up on the systemic failings of the permit-to-work system. The Cullen Report included a recommendation to shift the regulatory regime to a greater focus on SMS audit rather than on inspection.
Contractor management. It had been the first day on the platform for the production operator, who was a contractor and was left on his own without any operating procedures.
Management of change. The platform, originally thought for oil production only, was retrofitted to handle gas. The change was not properly thought out and assessed, as the placement of critical gas facilities next to the unprotected control room stood to demonstrate.
Asset integrity, by way of inspection and maintenance. Safety-critical systems such as liferafts, fire pumps, or emergency lighting do not seem to have received proper attention.
In general, Piper Alpha marked a watershed moment in that it ushered in a greater focus on process safety management and on a risk-based, rather than purely prescriptive, hazard management. As a result of the tragedy, the Safety Case Regulations came into force in 1992. By late 1993, a safety case had to be submitted to the Health and Safety Executive for every platform and rig in British waters (including the exclusive economic zone). The safety case must describe and justify the design, inherent hazards and residual risk in the spirit of the ALARP (as low as reasonably practicable) principle, as well as the means of managing such residual risk. The safety case must be maintained up to date through the lifecycle of the installation.
The safety case regime has been ascribed a measure of success in promoting safer facility design and management of offshore operations in the United Kingdom. Trade association Oil and Gas UK linked a significant fall in lost time injury frequency rate observed since 1997 to the introduction of the regime. The decrease in the number of accidental hydrocarbon release events in the British offshore oil and gas industry has also been correlated to the new regulatory approach. A study commissioned by the Health and Safety executive found that the regime heightened awareness of risks throughout the industry and set in motion a more structured decision-making process targeting risk reduction efforts, safety management system improvements, and a better safety culture. According to another source, Piper was the catalyst for a development from an unsystematic, albeit well-meaning, collection of standards and processes to a systematized approach specific to safety.
However, some criticism of the safety case approach has also been voiced, pointing to implementation and communication problems as well as issues with the supporting safety studies. The industry's cost-cutting initiatives as well as the handling of workers' involvement in the development of safety cases have also been identified as potential factors of degradation of the safety case regime.
The safety case regime has been adopted outside the United Kingdom, both as a regulatory instrument (for example in Australia, Malaysia, and Norway, among others) and as a voluntary initiative taken by several oil companies. In the United States, the American Petroleum Institute's Recommended Practice 75 for Development of a Safety and Environmental Management Program for Outer Continental Shelf (OCS) Operations and Facilities was issued, at least in part, in response to the tragedy.
In terms of facility design, some of the Cullen Report's recommendations have become tenets for the safe design of offshore oil and gas installations:
Systematic identification and assessment of fire and explosion hazards.
Analysis of and protection against smoke and gas ingress as well as survivability against fire and explosion of a temporary refuge (usually within, and potentially extending to the entirety of, the living quarters), where the crew could muster and wait out the accident, while arrangements for emergency management and/or facility evacuation are put in place.
Analysis of escape routes and means of evacuation, with due regards to their survivability, accessibility and redundancy.
Analysis of the survivability of safety-critical systems required for emergency management, such as emergency shutdown valves (in particular those along hydrocarbon risers), primary structural elements, hydrocarbon piping and vessels, fire pumps, firewater distribution and deluge, control and radio rooms, public announcement and general alarm system, emergency sources of power, emergency lighting, all of which failed on Piper, additionally to the aforementioned impairments of escape routes and safe muster area.
These analyses, which are called "forthwith studies" by the Cullen Report, are now standard engineering deliverables in the design of offshore oil and gas facilities. Quantified risk assessment (QRA) also became more common, particularly in support to ALARP arguments. One effect of these studies was that a rectangular (rather than square) layout became common for new North Sea platforms, to allow for increased spacing between vulnerable areas and major hazard modules. For the same reason, bridge-linked platforms became more common to increase separation from the accommodation module. Other lessons learnt in design were the importance of blast walls in protecting safety-critical systems; the need to minimize congestion and promote natural ventilation in process areas, to decrease the chance of explosions; the need to ensure that the temporary refuge HVAC system be capable to repel smoke and gas ingress by positive pressurization and implementation of gas-tight dampers automatically actuated from smoke and gas detectors; redundancy of critical communication systems, like radio and public address; remote start of fire pumps; need to optimize the location and fireproofing of riser emergency shutdown valves; assessment for the need of subsea pipeline isolation valves, to segregate the amount of hydrocarbon available for fire escalation in case of riser or riser valve failure. The resulting changes in the design philosophy of offshore facilities have therefore been towards an inherently safer design (ISD) concept.
In the same spirit, companies also sought to decrease the number of operators needed to run offshore facilities, in an attempt to reduce human exposure to major accidents. The first totally unoccupied (normally unmanned) installation, in the Amethyst gas field, was commissioned in September 1990. There is debate as to whether unmanned facilities are actually beneficial in terms of decreasing risk to the workers, given the requirements to transfer personnel to and from the platform (for inspection and maintenance activities), which in itself carries an amount of risk associated to helicopter flights, boating, and boat-to-platform personnel transfer.
Memorials
A condolence banner was gifted in 1989 by the Victorian Trades Hall Council of Australia, and is now in the Aberdeen Maritime Museum.
On 6 July 1991, the third anniversary of the disaster, a memorial sculpture was unveiled by the Queen Mother in the Rose Garden within Hazlehead Park in Aberdeen. In it are three figures of oil workers, one facing west and representing the physical nature of offshore activities, one facing east and representing eternal movement and youth and the central one, facing north and whose left hand holds a pool of oil sculpted in the shape of an unwinding spiral. It was created by Sue Jane Taylor, a Scottish sculptor who based much of her work around what she saw in and around the oil industry and had actually visited Piper Alpha in 1987. One of the survivors was used as a model for one of the figures. Also in 1991, Scottish composer James MacMillan wrote Tuireadh, a piece for clarinet and string quartet, as a musical complement to the memorial sculpture.
A memorial stone was erected in 1992 in Strathclyde Country Park to commemorate the men lost from that region.
The Piper Alpha Window was created in 1994 by congregation member Jennifer Jane Bayliss for Ferryhill Church in Aberdeen.
The Oil Chapel in the Kirk of St Nicholas, Aberdeen was dedicated in 1990 to mark 25 years of North Sea oil. The chapel hosts a book of remembrance to all those who have died offshore in British waters.
In the media
The incident was featured in the 1990 STV documentary television series Rescue, about the RAF Search and Rescue Force at RAF Lossiemouth, in the episode "Piper Alpha". Coincidentally, the film crew had been documenting the rescue teams at Lossiemouth at the time of accident and were able to accompany the helicopter during the Piper Alpha disaster, filming events as they happened from helicopter Rescue 138.
The disaster was featured in the first episode of the BBC television series Disaster, aired in January 1997.
In 1998, on the occasion of the 10th anniversary, Prospero Productions of Australia released the documentary Paying for the Piper. It was written and produced by Ed Punchard, who was one of the divers that managed to escape the inferno. The film follows Punchard's return to Scotland to confront his past and culminates in a meeting with Occidental officers.
In 2004, National Geographic featured this incident in its Seconds from Disaster documentary as the episode "Explosion in the North Sea".
On 6 July 2008, BBC Radio 3 broadcast a 90-minute play by Stephen Phelps entitled Piper Alpha. Based on the actual evidence given to the Cullen Inquiry, the events of that night were retold 20 years to the minute after they happened.
Also in 2008, to mark the 20th anniversary of the disaster, a stage play, Lest We Forget was commissioned by Aberdeen Performing Arts and written by playwright Mike Gibb. It was performed in Aberdeen in the week leading up to the anniversary with the final performance on 6 July 2008, the 20th anniversary.
In 2011, Lee Hutcheon produced and directed The Men of Piper Alpha, a documentary with several interviews to the survivors.
In 2013, on the 25th anniversary of the disaster, the video Remembering Piper: The Night That Changed Our World was released by British offshore oil and gas industry initiative Step Change in Safety. It incorporates passages from the BBC radio play and artwork by Sue Jane Taylor.
The documentary film Fire in the Night was also released in 2013. It was made by Berriff McGinty Films and co-produced by STV. Producer and cameraman Paul Berriff had been with Sea King Rescue 138 during the filming of the Rescue series.
In 2017 the episode "Oil Rig Explosion" of the Smithsonian Channel documentary series Make It Out Alive! focused on the disaster, with interviews to, among others, Geoff Bollands, Iain Letham, Charles Haffey, and Paul Berriff.
In 2018, a special edition of the Monopoly board game was released to commemorate the 30th anniversary of the tragedy. It was sponsored by a number of companies working in the North Sea offshore oil and gas industry, including majors such as Shell, whose Brent platforms substituted for the four train station squares. The game release was part of a fundraiser for the maintenance costs of the memorial in Hazlehead Park. The box lid prominently featured Piper Alpha imagery and a "Piper Alpha 30th Anniversary" title, which led the game to be referred to as the "Piper Alpha Monopoly". The reactions of some of the survivors and victims' families were negative, calling the game "callous" and a "sick joke". The game was re-released with a different design to clarify that it was really an oil-and-gas (and not a Piper Alpha-themed) Monopoly edition.
Also in 2018, the disaster was featured on the History documentary series James Nesbitt's Disasters That Changed Britain. Testimonials were heard from survivors and relatives of victims.
In 2023, to mark the 35th anniversary, writer Mike Gibb adapted his stage play as a novel titled I Had Never Heard a City Cry Before, a quote from the script.
See also
Alexander L. Kielland
Ocean Ranger
Mumbai High disaster
Deepwater Horizon explosion
Explanatory notes
References
Bibliography
Volume 1 (archived from the original on 2 May 2007, retrieved 18 December 2005).
Volume 2 (archived from the original on 8 February 2007, retrieved 18 December 2005).
Volume 3 (archived from the original on 25 August 2007, retrieved 18 December 2005).
Volume 4 (archived from the original on 25 August 2007, retrieved 18 December 2005).
Volume 5 (archived from the original on 25 August 2007, retrieved 18 December 2005).
Volume 6 (archived from the original on 3 December 2006, retrieved 18 December 2005).
Volume 1 (archived from the original on 6 November 2023, retrieved 20 December 2023).
Volume 2 (archived from the original on 16 December 2023, retrieved 20 December 2023).
Further reading
External links
Links (archived) to all the opinions of the Lords of the Court of Session at first instance and in reclaiming motions of the civil proceedings
"On This Day" (archived) – BBC News article (6 July 1988)
"Piper Alpha Case History" (archived) by the Center for Chemical Process Safety of AIChE
"Piper 25 Conference – Steve Rae" – presentation by a survivor, video on YouTube
"Piper Alpha 25th Anniversary Rededication and Act of Remembrance" from Offshore Energies UK's channel on Vimeo
"Piper Alpha Disaster" (archived) on Education Scotland's website
Collapsed oil platforms
Oil platforms off Scotland
Natural gas platforms
1988 disasters in the United Kingdom
1988 in Scotland
Gas explosions in the United Kingdom
Explosions in Scotland
History of Aberdeen
History of the North Sea
July 1988 events in the United Kingdom
North Sea energy
1988 industrial disasters
Industrial fires and explosions in the United Kingdom
Explosions in 1988
Oil platform disasters
Maritime incidents involving engineering failures
Maritime incidents in 1988
Public inquiries in Scotland
1976 establishments in Scotland
1988 disestablishments in Scotland
Building and structure collapses in the United Kingdom
Building and structure collapses caused by fire | Piper Alpha | Engineering | 9,634 |
72,543,322 | https://en.wikipedia.org/wiki/B3%201715%2B425 | B3 1715+425 is an astronomical radio source which is theorized to be a nearly naked black hole.
Discovery
B3 1715+425 was discovered during a systematic search for supermassive black holes (SMBH) by James Condon and his team at the National Radio Astronomy Observatory in 2016. Condon recalls how his team had been looking for “orbiting pairs of supermassive black holes, with one offset from the centre of a galaxy, as telltale evidence of a previous galaxy merger.” Instead, they found B3 1715+425.
Description
It is speculated that B3 1715+425 was originally enclosed by a host galaxy, like most other SMBHs. Models predict that in most black hole collisions, the two objects will combine to form a larger black hole. However, in B3 1715+425‘s case, Condon speculates that a collision with a much larger galaxy resulted in most of the host galaxy for B3 1715+425 being pulled away, leaving it with a small remaining galaxy of diameter just 3,000 lightyears across (in comparison, the Milky Way Galaxy is 87,400 light years across). The galaxy responsible for removing most B3 1715+425's stars is an elliptical brightest cluster galaxy at the center of the ZwCl 8193 cluster. The galaxy shows a distorted morphology and a starburst, probably as a result of the interaction with B3 1715+425.
Resources
Supermassive black holes | B3 1715+425 | Physics | 299 |
3,628,702 | https://en.wikipedia.org/wiki/On%20Demand%20Routing | On-Demand Routing ("ODR") is an enhancement to Cisco Discovery Protocol (CDP), a protocol used to discover other Cisco devices on either broadcast or non-broadcast media.
With the help of CDP, it is possible to find the device type, the IP address, the Cisco IOS version running on the neighbor Cisco device, the capabilities of the neighbor device, and so on. In Cisco IOS software release 11.2, ODR was added to CDP to advertise the connected IP prefix of a stub router via CDP. This feature takes an extra five bytes for each network or subnet, four Bytes for the IP address, and one byte to advertise the subnet mask along with the IP. ODR is able to carry Variable Length Subnet Mask (VLSM) information.
External links
ODR, Cisco introduction to ODR
Cisco protocols | On Demand Routing | Technology | 180 |
33,911,961 | https://en.wikipedia.org/wiki/Batch%20coding%20machine | Batch printing machines, marking machines, and date printing machines are used in the following applications:
Printing batch numbers, manufacturing date, expiration date, retail price, and other information on their plain or laminated and varnished labels, cartons, polypack bags, pouches, tin bottoms, cotton bags, bottles, jars or any solid surfaces.
Adding special information at the time of packing.
Adding price change or special offer on existing labels or cartons.
Types of machine
Batch coding machines are categorized in the following two categories:
Contact coding type
Non contact coding type
These coding machines are further sub categorized into the following types depending on their mode of operation:
Automatic
Once set, works automatically with the operator only having to look after its working and settings.
Feeding, printing, collecting operation are done automatically, however these features vary in the different makes of machines.
Semi-automatic
The machine works on its own but the feeding and collecting has to be done by hand.
Hand operated or manual
Feeding as well as the machine are operated manually. They are suitable for small production and are highly portable.
Online
These machine works automatically online with other machines or they can be of continuous type with feeding from other machine, by hand or other feeding mechanisms, but are integrated or attached in line with other online machines.
Contact coding type
These machines print or mark on products by contacting the product surface. They mostly use some letters made up of metal or rubber and ink media like liquid ink or a ribbon or solid ink etc. to make an impression. The letters are made offset, so while printing they give mirror image and straight print is obtained.
Non contact coding type
These machine do not comes in contact in any way while printing or marking on products. Normally these machine uses beams/spray to mark. These beams may be emanating from laser, or the spray of ink, the most important factor is that the product or machine should be moving at constant speed.
The moving product are sensed by a sensor & give a signal to the machine which responds immediately with the printing.
These machine also work as online machines. A few machines in this category are Inkjet printer, Laser printer, industrial Inkjet coding machine, laser marking systems.
References
Packaging machinery | Batch coding machine | Engineering | 447 |
11,009,430 | https://en.wikipedia.org/wiki/Systems%20simulation | Computers are used to generate numeric models for the purpose of describing or displaying complex interaction among multiple variables within a system. The complexity of the system arises from the stochastic (probabilistic) nature of the events, rules for the interaction of the elements and the difficulty in perceiving the behavior of the systems as a whole with the passing of time.
Systems Simulation in Video Games
One of the most notable video games to incorporate systems simulation is Sim City, which simulates the multiple systems of a functioning city including but not limited to: electricity, water, sewage, public transportation, population growth, social interactions (including, but not limited to jobs, education and emergency response).
See also
Agent-based model
Discrete event simulation
NetLogo
Systems Dynamics
References
External links
A Brief Introduction to Systems Simulation
Resources and Courses in Systems Simulation
Guide to the Winter Simulation Conference Collection 1968-2003, 2013-2014
Stochastic simulation
Systems theory | Systems simulation | Technology | 190 |
29,162,348 | https://en.wikipedia.org/wiki/Stadtpilot | Stadtpilot is a project of the Braunschweig University of Technology, Germany. Following the qualification for the DARPA Grand Challenge (2007) with the project CarOLO, this project aims to send the cars Henry and Leonie on a course through the Braunschweig inner city (Stadtring).
On October 8, 2010, Leonie was sent on the Stadtring course in real urban traffic; reportedly being the first in the world to do so.
Footnotes
Self-driving cars
Research and development in Germany | Stadtpilot | Engineering | 108 |
30,894,489 | https://en.wikipedia.org/wiki/Exon-intron%20database | The Exon-Intron Database (EID) is a database of spliced mRNA sequences.
See also
Alternative splicing
Exon
Intron
References
External links
Homepage
Biological databases
Gene expression
Spliceosome
RNA splicing | Exon-intron database | Chemistry,Biology | 50 |
8,921,892 | https://en.wikipedia.org/wiki/British%20Society%20of%20Master%20Glass%20Painters | The British Society of Master Glass Painters (BSMGP) is a British trade association for the art and craft of stained glass. Founded in 1921, it is a membership organisation which exists to represent the trade of glass painting and staining in Britain. The founding subscribers included John Hardman, Walter Tower (Kempe & Co), Arthur Powell (James Powell and Sons) and Thomas Grylls (Burlison & Grylls) and Percy Bacon.
BSMGP activities include: lectures, conferences, exhibitions, forums, and guided walks. It also offers publications such as an annual journal and a quarterly newsletter. Additionally, it houses an extensive reference library, available to its members only.
The current president is Prince Richard, Duke of Gloucester.
See also
Worshipful Company of Glaziers and Painters of Glass
References
External links
The British Society of Master Glass Painters
Glass makers
Crafts organizations
Design institutions
Architecture organisations based in the United Kingdom
Arts organizations established in 1921
Arts organisations based in the United Kingdom
1921 establishments in the United Kingdom | British Society of Master Glass Painters | Engineering | 208 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.