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Adverse events
Acupuncture is generally safe when administered by an experienced, appropriately trained practitioner using clean-needle technique and sterile single-use needles. When improperly delivered it can cause adverse effects. Accidents and infections are associated with infractions of sterile technique or neglect on the part of the practitioner. To reduce the risk of serious adverse events after acupuncture, acupuncturists should be trained sufficiently. A 2009 overview of Cochrane reviews found acupuncture is not effective for a wide range of conditions. People with serious spinal disease, such as cancer or infection, are not good candidates for acupuncture. Contraindications to acupuncture (conditions that should not be treated with acupuncture) include coagulopathy disorders (e.g. hemophilia and advanced liver disease), warfarin use, severe psychiatric disorders (e.g. psychosis), and skin infections or skin trauma (e.g. burns). Further, electroacupuncture should be avoided at the spot of implanted electrical devices (such as pacemakers).
A 2011 systematic review of systematic reviews (internationally and without language restrictions) found that serious complications following acupuncture continue to be reported. Between 2000 and 2009, ninety-five cases of serious adverse events, including five deaths, were reported. Many such events are not inherent to acupuncture but are due to malpractice of acupuncturists. This might be why such complications have not been reported in surveys of adequately trained acupuncturists. Most such reports originate from Asia, which may reflect the large number of treatments performed there or a relatively higher number of poorly trained Asian acupuncturists. Many serious adverse events were reported from developed countries. These included Australia, Austria, Canada, Croatia, France, Germany, Ireland, the Netherlands, New Zealand, Spain, Sweden, Switzerland, the UK, and the US. The number of adverse effects reported from the UK appears particularly unusual, which may indicate less under-reporting in the UK than other countries. Reports included 38 cases of infections and 42 cases of organ trauma. The most frequent adverse events included pneumothorax, and bacterial and viral infections. | Acupuncture | Wikipedia | 463 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
A 2013 review found (without restrictions regarding publication date, study type or language) 295 cases of infections; mycobacterium was the pathogen in at least 96%. Likely sources of infection include towels, hot packs or boiling tank water, and reusing reprocessed needles. Possible sources of infection include contaminated needles, reusing personal needles, a person's skin containing mycobacterium, and reusing needles at various sites in the same person. Although acupuncture is generally considered a safe procedure, a 2013 review stated that the reports of infection transmission increased significantly in the prior decade, including those of mycobacterium. Although it is recommended that practitioners of acupuncture use disposable needles, the reuse of sterilized needles is still permitted. It is also recommended that thorough control practices for preventing infection be implemented and adapted. | Acupuncture | Wikipedia | 179 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
English-language
A 2013 systematic review of the English-language case reports found that serious adverse events associated with acupuncture are rare, but that acupuncture is not without risk. Between 2000 and 2011 the English-language literature from 25 countries and regions reported 294 adverse events. The majority of the reported adverse events were relatively minor, and the incidences were low. For example, a prospective survey of 34,000 acupuncture treatments found no serious adverse events and 43 minor ones, a rate of 1.3 per 1000 interventions. Another survey found there were 7.1% minor adverse events, of which 5 were serious, amid 97,733 acupuncture patients. The most common adverse effect observed was infection (e.g. mycobacterium), and the majority of infections were bacterial in nature, caused by skin contact at the needling site. Infection has also resulted from skin contact with unsterilized equipment or with dirty towels in an unhygienic clinical setting. Other adverse complications included five reported cases of spinal cord injuries (e.g. migrating broken needles or needling too deeply), four brain injuries, four peripheral nerve injuries, five heart injuries, seven other organ and tissue injuries, bilateral hand edema, epithelioid granuloma, pseudolymphoma, argyria, pustules, pancytopenia, and scarring due to hot-needle technique. Adverse reactions from acupuncture, which are unusual and uncommon in typical acupuncture practice, included syncope, galactorrhoea, bilateral nystagmus, pyoderma gangrenosum, hepatotoxicity, eruptive lichen planus, and spontaneous needle migration.
A 2013 systematic review found 31 cases of vascular injuries caused by acupuncture, three causing death. Two died from pericardial tamponade and one was from an aortoduodenal fistula. The same review found vascular injuries were rare, bleeding and pseudoaneurysm were most prevalent. A 2011 systematic review (without restriction in time or language), aiming to summarize all reported case of cardiac tamponade after acupuncture, found 26 cases resulting in 14 deaths, with little doubt about cause in most fatal instances. The same review concluded that cardiac tamponade was a serious, usually fatal, though theoretically avoidable complication following acupuncture, and urged training to minimize risk. | Acupuncture | Wikipedia | 509 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
A 2012 review found that a number of adverse events were reported after acupuncture in the UK's National Health Service (NHS), 95% of which were not severe, though miscategorization and under-reporting may alter the total figures. From January 2009 to December 2011, 468 safety incidents were recognized within the NHS organizations. The adverse events recorded included retained needles (31%), dizziness (30%), loss of consciousness/unresponsive (19%), falls (4%), bruising or soreness at needle site (2%), pneumothorax (1%) and other adverse side effects (12%). Acupuncture practitioners should know, and be prepared to be responsible for, any substantial harm from treatments. Some acupuncture proponents argue that the long history of acupuncture suggests it is safe. However, there is an increasing literature on adverse events (e.g. spinal-cord injury).
Acupuncture seems to be safe in people getting anticoagulants, assuming needles are used at the correct location and depth, but studies are required to verify these findings.
Chinese, Korean, and Japanese-language | Acupuncture | Wikipedia | 250 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
A 2010 systematic review of the Chinese-language literature found numerous acupuncture-related adverse events, including pneumothorax, fainting, subarachnoid hemorrhage, and infection as the most frequent, and cardiovascular injuries, subarachnoid hemorrhage, pneumothorax, and recurrent cerebral hemorrhage as the most serious, most of which were due to improper technique. Between 1980 and 2009, the Chinese-language literature reported 479 adverse events. Prospective surveys show that mild, transient acupuncture-associated adverse events ranged from 6.71% to 15%. In a study with 190,924 patients, the prevalence of serious adverse events was roughly 0.024%. Another study showed a rate of adverse events requiring specific treatment of 2.2%, 4,963 incidences among 229,230 patients. Infections, mainly hepatitis, after acupuncture are reported often in English-language research, though are rarely reported in Chinese-language research, making it plausible that acupuncture-associated infections have been underreported in China. Infections were mostly caused by poor sterilization of acupuncture needles. Other adverse events included spinal epidural hematoma (in the cervical, thoracic and lumbar spine), chylothorax, injuries of abdominal organs and tissues, injuries in the neck region, injuries to the eyes, including orbital hemorrhage, traumatic cataract, injury of the oculomotor nerve and retinal puncture, hemorrhage to the cheeks and the hypoglottis, peripheral motor-nerve injuries and subsequent motor dysfunction, local allergic reactions to metal needles, stroke, and cerebral hemorrhage after acupuncture.
A causal link between acupuncture and the adverse events cardiac arrest, pyknolepsy, shock, fever, cough, thirst, aphonia, leg numbness, and sexual dysfunction remains uncertain. The same review concluded that acupuncture can be considered inherently safe when practiced by properly trained practitioners, but the review also stated there is a need to find effective strategies to minimize the health risks. Between 1999 and 2010, the Korean-language literature contained reports of 1104 adverse events. Between the 1980s and 2002, the Japanese-language literature contained reports of 150 adverse events. | Acupuncture | Wikipedia | 494 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
Children and pregnancy
Although acupuncture has been practiced for thousands of years in China, its use in pediatrics in the United States did not become common until the early 2000s. In 2007, the National Health Interview Survey (NHIS) conducted by the National Center For Health Statistics (NCHS) estimated that approximately 150,000 children had received acupuncture treatment for a variety of conditions.
In 2008, a study determined that the use of acupuncture-needle treatment on children was "questionable" due to the possibility of adverse side-effects and the pain manifestation differences in children versus adults. The study also includes warnings against practicing acupuncture on infants, as well as on children who are over-fatigued, very weak, or have over-eaten.
When used on children, acupuncture is considered safe when administered by well-trained, licensed practitioners using sterile needles; however, a 2011 review found there was limited research to draw definite conclusions about the overall safety of pediatric acupuncture. The same review found 279 adverse events, 25 of them serious. The adverse events were mostly mild in nature (e.g., bruising or bleeding). The prevalence of mild adverse events ranged from 10.1% to 13.5%, an estimated 168 incidences among 1,422 patients. On rare occasions adverse events were serious (e.g. cardiac rupture or hemoptysis); many might have been a result of substandard practice. The incidence of serious adverse events was 5 per one million, which included children and adults.
When used during pregnancy, the majority of adverse events caused by acupuncture were mild and transient, with few serious adverse events. The most frequent mild adverse event was needling or unspecified pain, followed by bleeding. Although two deaths (one stillbirth and one neonatal death) were reported, there was a lack of acupuncture-associated maternal mortality. Limiting the evidence as certain, probable or possible in the causality evaluation, the estimated incidence of adverse events following acupuncture in pregnant women was 131 per 10,000.
Although acupuncture is not contraindicated in pregnant women, some specific acupuncture points are particularly sensitive to needle insertion; these spots, as well as the abdominal region, should be avoided during pregnancy.
Moxibustion and cupping | Acupuncture | Wikipedia | 483 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
Four adverse events associated with moxibustion were bruising, burns and cellulitis, spinal epidural abscess, and large superficial basal cell carcinoma. Ten adverse events were associated with cupping. The minor ones were keloid scarring, burns, and bullae; the serious ones were acquired hemophilia A, stroke following cupping on the back and neck, factitious panniculitis, reversible cardiac hypertrophy, and iron deficiency anemia.
Risk of forgoing conventional medical care
As with other alternative medicines, unethical or naïve practitioners may induce patients to exhaust financial resources by pursuing ineffective treatment. Professional ethics codes set by accrediting organizations such as the National Certification Commission for Acupuncture and Oriental Medicine require practitioners to make "timely referrals to other health care professionals as may be appropriate." Stephen Barrett states that there is a "risk that an acupuncturist whose approach to diagnosis is not based on scientific concepts will fail to diagnose a dangerous condition".
Conceptual basis
Traditional
Acupuncture is a substantial part of traditional Chinese medicine (TCM). Early acupuncture beliefs relied on concepts that are common in TCM, such as a life force energy called qi. Qi was believed to flow from the body's primary organs (zang-fu organs) to the "superficial" body tissues of the skin, muscles, tendons, bones, and joints, through channels called meridians. Acupuncture points where needles are inserted are mainly (but not always) found at locations along the meridians. Acupuncture points not found along a meridian are called extraordinary points and those with no designated site are called points.
In TCM, disease is generally perceived as a disharmony or imbalance in energies such as yin, yang, qi, xuĕ, zàng-fǔ, meridians, and of the interaction between the body and the environment. Therapy is based on which "pattern of disharmony" can be identified. For example, some diseases are believed to be caused by meridians being invaded with an excess of wind, cold, and damp. In order to determine which pattern is at hand, practitioners examine things like the color and shape of the tongue, the relative strength of pulse-points, the smell of the breath, the quality of breathing, or the sound of the voice. TCM and its concept of disease does not strongly differentiate between the cause and effect of symptoms.
Purported scientific basis | Acupuncture | Wikipedia | 512 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
Many within the scientific community consider acupuncture to be quackery and pseudoscience, having no effect other than as "theatrical placebo". David Gorski has argued that of all forms of quackery, acupuncture has perhaps gained most acceptance among physicians and institutions. Academics Massimo Pigliucci and Maarten Boudry describe acupuncture as a "borderlands science" lying between science and pseudoscience.
Rationalizations of traditional medicine
It is a generally held belief within the acupuncture community that acupuncture points and meridians structures are special conduits for electrical signals, but no research has established any consistent anatomical structure or function for either acupuncture points or meridians. Human tests to determine whether electrical continuity was significantly different near meridians than other places in the body have been inconclusive. Scientific research has not supported the existence of qi, meridians, or yin and yang. A Nature editorial described TCM as "fraught with pseudoscience", with the majority of its treatments having no logical mechanism of action. Quackwatch states that "TCM theory and practice are not based upon the body of knowledge related to health, disease, and health care that has been widely accepted by the scientific community. TCM practitioners disagree among themselves about how to diagnose patients and which treatments should go with which diagnoses. Even if they could agree, the TCM theories are so nebulous that no amount of scientific study will enable TCM to offer rational care." Academic discussions of acupuncture still make reference to pseudoscientific concepts such as qi and meridians despite the lack of scientific evidence.
Release of endorphins or adenosine
Some modern practitioners support the use of acupuncture to treat pain, but have abandoned the use of qi, meridians, yin, yang and other mystical energies as an explanatory frameworks. The use of qi as an explanatory framework has been decreasing in China, even as it becomes more prominent during discussions of acupuncture in the US. | Acupuncture | Wikipedia | 432 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
Many acupuncturists attribute pain relief to the release of endorphins when needles penetrate, but no longer support the idea that acupuncture can affect a disease. Some studies suggest acupuncture causes a series of events within the central nervous system, and that it is possible to inhibit acupuncture's analgesic effects with the opioid antagonist naloxone. Mechanical deformation of the skin by acupuncture needles appears to result in the release of adenosine. The anti-nociceptive effect of acupuncture may be mediated by the adenosine A1 receptor. A 2014 review in Nature Reviews Cancer analyzed mouse studies that suggested acupuncture relieves pain via the local release of adenosine, which then triggered nearby A1 receptors. The review found that in those studies, because acupuncture "caused more tissue damage and inflammation relative to the size of the animal in mice than in humans, such studies unnecessarily muddled a finding that local inflammation can result in the local release of adenosine with analgesic effect."
History
Origins
Acupuncture, along with moxibustion, is one of the oldest practices of traditional Chinese medicine. Most historians believe the practice began in China, though there are some conflicting narratives on when it originated. Academics David Ramey and Paul Buell said the exact date acupuncture was founded depends on the extent to which dating of ancient texts can be trusted and the interpretation of what constitutes acupuncture.
Acupressure therapy was prevalent in India. Once Buddhism spread to China, the acupressure therapy was also integrated into common medical practice in China and it came to be known as acupuncture. The major points of Indian acupressure and Chinese acupuncture are similar to each other. | Acupuncture | Wikipedia | 379 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
According to an article in Rheumatology, the first documentation of an "organized system of diagnosis and treatment" for acupuncture was in Inner Classic of Huang Di (Huangdi Neijing) from about 100 BC. Gold and silver needles found in the tomb of Liu Sheng from around 100 BC are believed to be the earliest archaeological evidence of acupuncture, though it is unclear if that was their purpose. According to Plinio Prioreschi, the earliest known historical record of acupuncture is the Shiji ("Records of the Grand Historian"), written by a historian around 100 BC. It is believed that this text was documenting what was established practice at that time.
Alternative theories
The 5,000-year-old mummified body of Ötzi the Iceman was found with 15 groups of tattoos, many of which were located at points on the body where acupuncture needles are used for abdominal or lower back problems. Evidence from the body suggests Ötzi had these conditions. This has been cited as evidence that practices similar to acupuncture may have been practised elsewhere in Eurasia during the early Bronze Age; however, The Oxford Handbook of the History of Medicine calls this theory "speculative". It is considered unlikely that acupuncture was practised before 2000 BC.
Acupuncture may have been practised during the Neolithic era, near the end of the Stone Age, using sharpened stones called Bian shi. Many Chinese texts from later eras refer to sharp stones called "plen", which means "stone probe", that may have been used for acupuncture purposes. The ancient Chinese medical text, Huangdi Neijing, indicates that sharp stones were believed at-the-time to cure illnesses at or near the body's surface, perhaps because of the short depth a stone could penetrate. However, it is more likely that stones were used for other medical purposes, such as puncturing a growth to drain its pus. The Mawangdui texts, which are believed to be from the 2nd century BC, mention the use of pointed stones to open abscesses, and moxibustion, but not for acupuncture. It is also speculated that these stones may have been used for bloodletting, due to the ancient Chinese belief that illnesses were caused by demons within the body that could be killed or released. It is likely bloodletting was an antecedent to acupuncture. | Acupuncture | Wikipedia | 503 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
According to historians Lu Gwei-djen and Joseph Needham, there is substantial evidence that acupuncture may have begun around 600 BC. Some hieroglyphs and pictographs from that era suggests acupuncture and moxibustion were practised. However, historians Lu and Needham said it was unlikely a needle could be made out of the materials available in China during this time period. It is possible that bronze was used for early acupuncture needles. Tin, copper, gold and silver are also possibilities, though they are considered less likely, or to have been used in fewer cases. If acupuncture was practised during the Shang dynasty (1766 to 1122 BC), organic materials like thorns, sharpened bones, or bamboo may have been used. Once methods for producing steel were discovered, it would replace all other materials, since it could be used to create a very fine, but sturdy needle. Lu and Needham noted that all the ancient materials that could have been used for acupuncture and which often produce archaeological evidence, such as sharpened bones, bamboo or stones, were also used for other purposes. An article in Rheumatology said that the absence of any mention of acupuncture in documents found in the tomb of Mawangdui from 198 BC suggest that acupuncture was not practised by that time.
Belief systems
Several different and sometimes conflicting belief systems emerged regarding acupuncture. This may have been the result of competing schools of thought. Some ancient texts referred to using acupuncture to cause bleeding, while others mixed the ideas of blood-letting and spiritual ch'i energy. Over time, the focus shifted from blood to the concept of puncturing specific points on the body, and eventually to balancing Yin and Yang energies as well. According to David Ramey, no single "method or theory" was ever predominantly adopted as the standard. At the time, scientific knowledge of medicine was not yet developed, especially because in China dissection of the deceased was forbidden, preventing the development of basic anatomical knowledge. | Acupuncture | Wikipedia | 422 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
It is not certain when specific acupuncture points were introduced, but the autobiography of Bian Que from around 400–500 BC references inserting needles at designated areas. Bian Que believed there was a single acupuncture point at the top of one's skull that he called the point "of the hundred meetings." Texts dated to be from 156 to 186 BC document early beliefs in channels of life force energy called meridians that would later be an element in early acupuncture beliefs.
Ramey and Buell said the "practice and theoretical underpinnings" of modern acupuncture were introduced in The Yellow Emperor's Classic (Huangdi Neijing) around 100 BC. It introduced the concept of using acupuncture to manipulate the flow of life energy (qi) in a network of meridian (channels) in the body. The network concept was made up of acu-tracts, such as a line down the arms, where it said acupoints were located. Some of the sites acupuncturists use needles at today still have the same names as those given to them by the Yellow Emperor's Classic. Numerous additional documents were published over the centuries introducing new acupoints. By the 4th century AD, most of the acupuncture sites in use today had been named and identified.
Early development in China
Establishment and growth
In the first half of the 1st century AD, acupuncturists began promoting the belief that acupuncture's effectiveness was influenced by the time of day or night, the lunar cycle, and the season. The 'science of the yin-yang cycles' ( ) was a set of beliefs that curing diseases relied on the alignment of both heavenly () and earthly () forces that were attuned to cycles like that of the sun and moon. There were several different belief systems that relied on a number of celestial and earthly bodies or elements that rotated and only became aligned at certain times. According to Needham and Lu, these "arbitrary predictions" were depicted by acupuncturists in complex charts and through a set of special terminology. | Acupuncture | Wikipedia | 440 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
Acupuncture needles during this period were much thicker than most modern ones and often resulted in infection. Infection is caused by a lack of sterilization, but at that time it was believed to be caused by use of the wrong needle, or needling in the wrong place, or at the wrong time. Later, many needles were heated in boiling water, or in a flame. Sometimes needles were used while they were still hot, creating a cauterizing effect at the injection site. Nine needles were recommended in the Great Compendium of Acupuncture and Moxibustion from 1601, which may have been because of an ancient Chinese belief that nine was a magic number.
Other belief systems were based on the idea that the human body operated on a rhythm and acupuncture had to be applied at the right point in the rhythm to be effective. In some cases a lack of balance between Yin and Yang were believed to be the cause of disease.
In the 1st century AD, many of the first books about acupuncture were published and recognized acupuncturist experts began to emerge. The Zhen Jiu Jia Yi Jing, which was published in the mid-3rd century, became the oldest acupuncture book that is still in existence in the modern era. Other books like the Yu Gui Zhen Jing, written by the Director of Medical Services for China, were also influential during this period, but were not preserved. In the mid 7th century, Sun Simiao published acupuncture-related diagrams and charts that established standardized methods for finding acupuncture sites on people of different sizes and categorized acupuncture sites in a set of modules.
Acupuncture became more established in China as improvements in paper led to the publication of more acupuncture books. The Imperial Medical Service and the Imperial Medical College, which both supported acupuncture, became more established and created medical colleges in every province. The public was also exposed to stories about royal figures being cured of their diseases by prominent acupuncturists. By time the Great Compendium of Acupuncture and Moxibustion was published during the Ming dynasty (1368–1644 AD), most of the acupuncture practices used in the modern era had been established. | Acupuncture | Wikipedia | 470 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
Decline
By the end of the Song dynasty (1279 AD), acupuncture had lost much of its status in China. It became rarer in the following centuries, and was associated with less prestigious professions like alchemy, shamanism, midwifery and moxibustion. Additionally, by the 18th century, scientific rationality was becoming more popular than traditional superstitious beliefs. By 1757 a book documenting the history of Chinese medicine called acupuncture a "lost art". Its decline was attributed in part to the popularity of prescriptions and medications, as well as its association with the lower classes.
In 1822, the Chinese Emperor signed a decree excluding the practice of acupuncture from the Imperial Medical Institute. He said it was unfit for practice by gentlemen-scholars. In China acupuncture was increasingly associated with lower-class, illiterate practitioners. It was restored for a time, but banned again in 1929 in favor of science-based medicine. Although acupuncture declined in China during this time period, it was also growing in popularity in other countries.
International expansion
Korea is believed to be the first country in Asia that acupuncture spread to outside of China. Within Korea there is a legend that acupuncture was developed by emperor Dangun, though it is more likely to have been brought into Korea from a Chinese colonial prefecture in 514 AD. Acupuncture use was commonplace in Korea by the 6th century. It spread to Vietnam in the 8th and 9th centuries. As Vietnam began trading with Japan and China around the 9th century, it was influenced by their acupuncture practices as well. China and Korea sent "medical missionaries" that spread traditional Chinese medicine to Japan, starting around 219 AD. In 553, several Korean and Chinese citizens were appointed to re-organize medical education in Japan and they incorporated acupuncture as part of that system. Japan later sent students back to China and established acupuncture as one of five divisions of the Chinese State Medical Administration System. | Acupuncture | Wikipedia | 416 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
Acupuncture began to spread to Europe in the second half of the 17th century. Around this time the surgeon-general of the Dutch East India Company met Japanese and Chinese acupuncture practitioners and later encouraged Europeans to further investigate it. He published the first in-depth description of acupuncture for the European audience and created the term "acupuncture" in his 1683 work De Acupunctura. France was an early adopter among the West due to the influence of Jesuit missionaries, who brought the practice to French clinics in the 16th century. The French doctor Louis Berlioz (the father of the composer Hector Berlioz) is usually credited with being the first to experiment with the procedure in Europe in 1810, before publishing his findings in 1816.
By the 19th century, acupuncture had become commonplace in many areas of the world. Americans and Britons began showing interest in acupuncture in the early 19th century, although interest waned by mid-century. Western practitioners abandoned acupuncture's traditional beliefs in spiritual energy, pulse diagnosis, and the cycles of the moon, sun or the body's rhythm. Diagrams of the flow of spiritual energy, for example, conflicted with the West's own anatomical diagrams. It adopted a new set of ideas for acupuncture based on tapping needles into nerves. In Europe it was speculated that acupuncture may allow or prevent the flow of electricity in the body, as electrical pulses were found to make a frog's leg twitch after death.
The West eventually created a belief system based on Travell trigger points that were believed to inhibit pain. They were in the same locations as China's spiritually identified acupuncture points, but under a different nomenclature. The first elaborate Western treatise on acupuncture was published in 1683 by Willem ten Rhijne.
Modern era
In China, the popularity of acupuncture rebounded in 1949 when Mao Zedong took power and sought to unite China behind traditional cultural values. It was also during this time that many Eastern medical practices were consolidated under the name traditional Chinese medicine (TCM). | Acupuncture | Wikipedia | 441 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
New practices were adopted in the 20th century, such as using a cluster of needles, electrified needles, or leaving needles inserted for up to a week. A lot of emphasis developed on using acupuncture on the ear. Acupuncture research organizations such as the International Society of Acupuncture were founded in the 1940s and 1950s and acupuncture services became available in modern hospitals. China, where acupuncture was believed to have originated, was increasingly influenced by Western medicine. Meanwhile, acupuncture grew in popularity in the US. The US Congress created the Office of Alternative Medicine in 1992 and the National Institutes of Health (NIH) declared support for acupuncture for some conditions in November 1997. In 1999, the National Center for Complementary and Alternative Medicine was created within the NIH. Acupuncture became the most popular alternative medicine in the US.
Politicians from the Chinese Communist Party said acupuncture was superstitious and conflicted with the party's commitment to science. Communist Party Chairman Mao Zedong later reversed this position, arguing that the practice was based on scientific principles. During the Cultural Revolution, disbelief in acupuncture anesthesia was subjected to ruthless political repression.
In 1971, New York Times reporter James Reston published an article on his acupuncture experiences in China, which led to more investigation of and support for acupuncture. The US President Richard Nixon visited China in 1972. During one part of the visit, the delegation was shown a patient undergoing major surgery while fully awake, ostensibly receiving acupuncture rather than anesthesia. Later it was found that the patients selected for the surgery had both a high pain tolerance and received heavy indoctrination before the operation; these demonstration cases were also frequently receiving morphine surreptitiously through an intravenous drip that observers were told contained only fluids and nutrients. One patient receiving open heart surgery while awake was ultimately found to have received a combination of three powerful sedatives as well as large injections of a local anesthetic into the wound. After the National Institute of Health expressed support for acupuncture for a limited number of conditions, adoption in the US grew further. In 1972 the first legal acupuncture center in the US was established in Washington DC and in 1973 the American Internal Revenue Service allowed acupuncture to be deducted as a medical expense. | Acupuncture | Wikipedia | 490 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
In 2006, a BBC documentary Alternative Medicine filmed a patient undergoing open heart surgery allegedly under acupuncture-induced anesthesia. It was later revealed that the patient had been given a cocktail of anesthetics.
In 2010, UNESCO inscribed "acupuncture and moxibustion of traditional Chinese medicine" on the UNESCO Intangible Cultural Heritage List following China's nomination.
Adoption
Acupuncture is most heavily practiced in China and is popular in the US, Australia, and Europe. In Switzerland, acupuncture has become the most frequently used alternative medicine since 2004. In the United Kingdom, a total of 4 million acupuncture treatments were administered in 2009. Acupuncture is used in most pain clinics and hospices in the UK. An estimated 1 in 10 adults in Australia used acupuncture in 2004. In Japan, it is estimated that 25 percent of the population will try acupuncture at some point, though in most cases it is not covered by public health insurance. Users of acupuncture in Japan are more likely to be elderly and to have a limited education. Approximately half of users surveyed indicated a likelihood to seek such remedies in the future, while 37% did not. Less than one percent of the US population reported having used acupuncture in the early 1990s. By the early 2010s, more than 14 million Americans reported having used acupuncture as part of their health care.
In the US, acupuncture is increasingly () used at academic medical centers, and is usually offered through CAM centers or anesthesia and pain management services. Examples include those at Harvard University, Stanford University, Johns Hopkins University, and UCLA. CDC clinical practice guidelines from 2022 list acupuncture among the types of complementary and alternative medicines physicians should consider in preference to opioid prescription for certain kinds of pain. | Acupuncture | Wikipedia | 383 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
The use of acupuncture in Germany increased by 20% in 2007, after the German acupuncture trials supported its efficacy for certain uses. In 2011, there were more than one million users, and insurance companies have estimated that two-thirds of German users are women. As a result of the trials, German public health insurers began to cover acupuncture for chronic low back pain and osteoarthritis of the knee, but not tension headache or migraine. This decision was based in part on socio-political reasons. Some insurers in Germany chose to stop reimbursement of acupuncture because of the trials. For other conditions, insurers in Germany were not convinced that acupuncture had adequate benefits over usual care or sham treatments. Highlighting the results of the placebo group, researchers refused to accept a placebo therapy as efficient.
Regulation
There are various government and trade association regulatory bodies for acupuncture in the United Kingdom, the United States, Saudi Arabia, Australia, New Zealand, Japan, Canada, and in European countries and elsewhere. The World Health Organization recommends that an acupuncturist receive 200 hours of specialized training if they are a physician and 2,500 hours for non-physicians before being licensed or certified; many governments have adopted similar standards.
In Hong Kong, the practice of acupuncture is regulated by the Chinese Medicine Council, which was formed in 1999 by the Legislative Council. It includes a licensing exam, registration, and degree courses approved by the board. Canada has acupuncture licensing programs in the provinces of British Columbia, Ontario, Alberta and Quebec; standards set by the Chinese Medicine and Acupuncture Association of Canada are used in provinces without government regulation. Regulation in the US began in the 1970s in California, which was eventually followed by every state but Wyoming and Idaho. Licensing requirements vary greatly from state to state. The needles used in acupuncture are regulated in the US by the Food and Drug Administration. In some states acupuncture is regulated by a board of medical examiners, while in others by the board of licensing, health or education. | Acupuncture | Wikipedia | 442 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
In Japan, acupuncturists are licensed by the Minister of Health, Labour and Welfare after passing an examination and graduating from a technical school or university. In Australia, the Chinese Medicine Board of Australia regulates acupuncture, among other Chinese medical traditions, and restricts the use of titles like 'acupuncturist' to registered practitioners only. The practice of Acupuncture in New Zealand in 1990 acupuncture was included into the Governmental Accident Compensation Corporation (ACC) Act. This inclusion granted qualified and professionally registered acupuncturists the ability to provide subsidised care and treatment to citizens, residents, and temporary visitors for work- or sports-related injuries that occurred within the country of New Zealand. The two bodies for the regulation of acupuncture and attainment of ACC treatment provider status in New Zealand are Acupuncture NZ, and The New Zealand Acupuncture Standards Authority. At least 28 countries in Europe have professional associations for acupuncturists. In France, the Académie Nationale de Médecine (National Academy of Medicine) has regulated acupuncture since 1955. | Acupuncture | Wikipedia | 235 | 1537 | https://en.wikipedia.org/wiki/Acupuncture | Biology and health sciences | Alternative and traditional medicine | null |
Amaranthus is a cosmopolitan group of more than 50 species which make up the genus of annual or short-lived perennial plants collectively known as amaranths. Some of the better known names include "prostrate pigweed" and "love lies bleeding". Some amaranth species are cultivated as leaf vegetables, pseudocereals, and ornamental plants.
Catkin-like cymes of densely-packed flowers grow in summer or fall. Amaranth varies in flower, leaf, and stem color with a range of striking pigments from the spectrum of maroon to crimson and can grow longitudinally from tall with a cylindrical, succulent, fibrous stem that is hollow with grooves and bracteoles when mature.
There are approximately 75 species in the genus, 10 of which are dioecious and native to North America, and the remaining 65 are monoecious species that are endemic to every continent (except Antarctica) from tropical lowlands to the Himalayas. Members of this genus share many characteristics and uses with members of the closely related genus Celosia. Amaranth grain is collected from the genus. The leaves of some species are also eaten.
Names and etymology
Amaranthus comes from the name of this plant in Ancient Greek, , "amaranth, immortal", noun formed from the privative prefix , "without", and the verb , "to consume, to exhaust". Indeed, the amaranth has a reputation for not withering, with in particular its calice which remains persistent, and for this reason, represents a symbol of immortality. Some species are used in dry bouquets.
The form (with H), comes from an erroneous association with the Greek etymon (lat. ) meaning , found in the name of many plants (agapanthus, for example).
Its denominations in the languages of the peoples cultivating it since ancient times in America are in Nahuatl, , in Quechua, or in Maya, ahparie in Purépecha, in Huichol, and guegui in Tarahumara.
Description | Amaranth | Wikipedia | 428 | 1542 | https://en.wikipedia.org/wiki/Amaranth | Biology and health sciences | Caryophyllales | null |
Amaranth is a herbaceous plant or shrub that is either annual or perennial across the genus. Flowers vary interspecifically from the presence of 3 or 5 tepals and stamens, whereas a 7-porate pollen grain structure remains consistent across the family. Species across the genus contain concentric rings of vascular bundles, and fix carbon efficiently with a C4 photosynthetic pathway. Leaves are approximately and of oval or elliptical shape that are either opposite or alternate across species, although most leaves are whole and simple with entire margins.
Amaranth has a primary root with deeper spreading secondary fibrous root structures. Inflorescences are in the form a large panicle that varies from terminal to axial, color, and sex. The tassel of fluorescence is either erect or bent and varies in width and length between species. Flowers are radially symmetric and either bisexual or unisexual with very small, bristly perianth and pointy bracts. Species in this genus are either monecious (e.g. A. hybridus,) or dioecious (e.g. A. palmeri). Fruits are in the form of capsules referred to as a unilocular pixdio that opens at maturity. The top (operculum) of the unilocular pixdio releases the urn that contains the seed. Seeds are circular form from 1 to 1.5 millimeters in diameter and range in color with a shiny, smooth seed coat. The panicle is harvested 200 days after cultivation with approximately 1,000 to 3,000 seeds harvested per gram.
Chemistry
Amaranth grain contains phytochemicals that are not defined as nutrients and may be antinutrient factors, such as polyphenols, saponins, tannins, and oxalates. These compounds are reduced in content and antinutrient effect by cooking.
Taxonomy
Amaranthus shows a wide variety of morphological diversity among and even within certain species. Amaranthus is part of the Amaranthaceae that is part of the larger grouping of the Carophyllales. Although the family (Amaranthaceae) is distinctive, the genus has few distinguishing characters among the 75 species present across six continents. This complicates taxonomy and Amaranthus has generally been considered among systematists as a "difficult" genus and to hybridize often. | Amaranth | Wikipedia | 496 | 1542 | https://en.wikipedia.org/wiki/Amaranth | Biology and health sciences | Caryophyllales | null |
In 1955, Sauer classified the genus into two subgenera, differentiating only between monoecious and dioecious species: Acnida (L.) Aellen ex K.R. Robertson and Amaranthus. Although this classification was widely accepted, further infrageneric classification was (and still is) needed to differentiate this widely diverse group. Mosyakin and Robertson 1996 later divided into three subgenera: Acnida, Amaranthus, and Albersia. The support for the addition of the subdivision Albersia because of its indehiscent fruits coupled with three elliptic to linear tepals to be exclusive characters to members of this subgenus. The classification of these groups are further supported with a combination of floral characters, reproductive strategies, geographic distribution, and molecular evidence.
The phylogenies of Amaranthus using maximum parsimony and Bayesian analysis of nuclear and chloroplast genes suggest five clades within the genus: Diecious / Pumilus, Hybris, Galapagos, Eurasian/ South African, Australian (ESA), ESA + South American.
Amaranthus includes three recognised subgenera and 75 species, although species numbers are questionable due to hybridisation and species concepts. Infrageneric classification focuses on inflorescence, flower characters and whether a species is monoecious/dioecious, as in the Sauer (1955) suggested classification. Bracteole morphology present on the stem is used for taxonomic classification of Amaranth. Wild species have longer bracteoles compared to cultivated species. A modified infrageneric classification of Amaranthus includes three subgenera: Acnida, Amaranthus, and Albersia, with the taxonomy further differentiated by sections within each of the subgenera.
There is near certainty that A. hypochondriacus is the common ancestor to the cultivated grain species, however the later series of domestication to follow remains unclear. There has been opposing hypotheses of a single as opposed to multiple domestication events of the three grain species. There is evidence of phylogenetic and geographical support for clear groupings that indicate separate domestication events in South America and Central America. A. hybridus may derive from South America, whereas A. caudatus, A. hypochondriacus, and A. quentiensis are native to Central and North America.
Species
Species include: | Amaranth | Wikipedia | 499 | 1542 | https://en.wikipedia.org/wiki/Amaranth | Biology and health sciences | Caryophyllales | null |
Amaranthus acanthochiton – greenstripe
Amaranthus acutilobus – a synonym of Amaranthus viridis
Amaranthus albus – white pigweed, tumble pigweed
Amaranthus anderssonii
Amaranthus arenicola – sandhill amaranth
Amaranthus australis – southern amaranth
Amaranthus bigelovii – Bigelow's amaranth
Amaranthus blitoides – mat amaranth, prostrate amaranth, prostrate pigweed
Amaranthus blitum – purple amaranth
Amaranthus brownii – Brown's amaranth
Amaranthus californicus – California amaranth, California pigweed
Amaranthus cannabinus – tidal-marsh amaranth
Amaranthus caudatus – love-lies-bleeding, pendant amaranth, tassel flower, quilete
Amaranthus chihuahuensis – Chihuahuan amaranth
Amaranthus crassipes – spreading amaranth
Amaranthus crispus – crispleaf amaranth
Amaranthus cruentus – purple amaranth, red amaranth, Mexican grain amaranth
Amaranthus deflexus – large-fruit amaranth
Amaranthus dubius – spleen amaranth, khada sag
Amaranthus fimbriatus – fringed amaranth, fringed pigweed
Amaranthus floridanus – Florida amaranth
Amaranthus furcatus
Amaranthus graecizans
Amaranthus grandiflorus
Amaranthus greggii – Gregg's amaranth
Amaranthus hybridus – smooth amaranth, smooth pigweed, red amaranth
Amaranthus hypochondriacus – Prince-of-Wales feather, prince's feather
Amaranthus interruptus – Australian amaranth
Amaranthus minimus
Amaranthus mitchellii
Amaranthus muricatus – African amaranth
Amaranthus obcordatus – Trans-Pecos amaranth
Amaranthus palmeri – Palmer's amaranth, Palmer pigweed, careless weed
Amaranthus polygonoides – tropical amaranth
Amaranthus powellii – green amaranth, Powell amaranth, Powell pigweed
Amaranthus pringlei – Pringle's amaranth
Amaranthus pumilus – seaside amaranth
Amaranthus quitensis - Mucronate Amaranth | Amaranth | Wikipedia | 509 | 1542 | https://en.wikipedia.org/wiki/Amaranth | Biology and health sciences | Caryophyllales | null |
Amaranthus retroflexus – red-root amaranth, redroot pigweed, common amaranth
Amaranthus saradhiana - purpal stem amaranth, green leaf amaranth
Amaranthus scleranthoides – variously Amaranthus sclerantoides
Amaranthus scleropoides – bone-bract amaranth
Amaranthus spinosus – spiny amaranth, prickly amaranth, thorny amaranth
Amaranthus standleyanus
Amaranthus thunbergii – Thunberg's amaranth
Amaranthus torreyi – Torrey's amaranth
Amaranthus tricolor – Joseph's-coat
Amaranthus tuberculatus – rough-fruit amaranth, tall waterhemp
Amaranthus viridis – slender amaranth, green amaranth
Amaranthus watsonii – Watson's amaranth
Amaranthus wrightii – Wright's amaranth | Amaranth | Wikipedia | 206 | 1542 | https://en.wikipedia.org/wiki/Amaranth | Biology and health sciences | Caryophyllales | null |
Etymology
"Amaranth" derives from Greek (), "unfading", with the Greek word for "flower", (), factoring into the word's development as amaranth, the unfading flower. Amarant is an archaic variant. The name was first applied to the related Celosia (Amaranthus and Celosia share long-lasting dried flowers), as Amaranthus plants were not yet known in Europe.
Ecology
Amaranth weed species have an extended period of germination, rapid growth, and high rates of seed production, and have been causing problems for farmers since the mid-1990s. This is partially due to the reduction in tillage, reduction in herbicidal use and the evolution of herbicidal resistance in several species where herbicides have been applied more often. The following 9 species of Amaranthus are considered invasive and noxious weeds in the U.S. and Canada: A. albus, A. blitoides, A. hybridus, A. palmeri, A. powellii, A. retroflexus, A. spinosus, A. tuberculatus, and A. viridis.
A new herbicide-resistant strain of A. palmeri has appeared; it is glyphosate-resistant and so cannot be killed by herbicides using the chemical. Also, this plant can survive in tough conditions. The species Amaranthus palmeri (Palmer amaranth) causes the greatest reduction in soybean yields and has the potential to reduce yields by 17-68% in field experiments. Palmer amaranth is among the "top five most troublesome weeds" in the southeast of the United States and has already evolved resistances to dinitroaniline herbicides and acetolactate synthase inhibitors. This makes the proper identification of Amaranthus species at the seedling stage essential for agriculturalists. Proper weed control needs to be applied before the species successfully colonizes in the crop field and causes significant yield reductions.
An evolutionary lineage of around 90 species within the genus has acquired the carbon fixation pathway, which increases their photosynthetic efficiency. This probably occurred in the Miocene.
Uses
All parts of the plant are considered edible, though some may have sharp spines that need to be removed before consumption. Amaranth is high in oxalates, but this may be partially offset by its high calcium content.
Nutrition | Amaranth | Wikipedia | 501 | 1542 | https://en.wikipedia.org/wiki/Amaranth | Biology and health sciences | Caryophyllales | null |
Uncooked amaranth grain by weight is 12% water, 65% carbohydrates (including 7% dietary fiber), 14% protein, and 7% fat (table). A reference serving of uncooked amaranth grain provides of food energy, and is a rich source (20% or more of the Daily Value, DV) of protein, dietary fiber, pantothenic acid, vitamin B6, folate, and several dietary minerals (table). Uncooked amaranth is particularly rich in manganese (159% DV), phosphorus (80% DV), magnesium (70% DV), iron (59% DV), and selenium (34% DV). Amaranth has a high oxalate content.
Cooking decreases its nutritional value substantially across all nutrients, with only dietary minerals remaining at moderate levels. Cooked amaranth leaves are a rich source of vitamin A, vitamin C, calcium, and manganese, with moderate levels of folate, iron, magnesium, and potassium. Amaranth does not contain gluten.
History
The native range of the genus is cosmopolitan. In pre-Hispanic times, amaranth was cultivated by the Aztec and their tributary communities in a quantity very similar to maize. Known to the Aztecs as , amaranth is thought to have represented up to 80% of their energy consumption before the Spanish conquest. Another important use of amaranth throughout Mesoamerica was in ritual drinks and foods. To this day, amaranth grains are toasted much like popcorn and mixed with honey, molasses, or chocolate to make a treat called , meaning "joy" in Spanish.
While all species are believed to be native to the Americas, several have been cultivated and introduced to warm regions worldwide. Amaranth's cosmopolitan distribution makes it one of many plants providing evidence of pre-Columbian oceanic contact. The earliest archeological evidence for amaranth in the Old World was found in an excavation in Narhan, India, dated to 1000–800 BCE. | Amaranth | Wikipedia | 429 | 1542 | https://en.wikipedia.org/wiki/Amaranth | Biology and health sciences | Caryophyllales | null |
Because of its importance as a symbol of indigenous culture, its palatability, ease of cooking, and a protein that is particularly well-suited to human nutritional needs, interest in amaranth seeds (especially A. cruentus and A. hypochondriacus) revived in the 1970s. It was recovered in Mexico from wild varieties and is now commercially cultivated. It is a popular snack in Mexico, sometimes mixed with chocolate or puffed rice, and its use has spread to Europe and other parts of North America.
Seed
Several species are raised for amaranth "grain" in Asia and the Americas. Amaranth and its relative quinoa are considered pseudocereals because of their similarities to cereals in flavor and cooking. The spread of Amaranthus is of a joint effort of human expansion, adaptation, and fertilization strategies. Grain amaranth has been used for food by humans in several ways. The grain can be ground into a flour for use like other grain flours. It can be popped like popcorn, or flaked like oatmeal.
Seeds of Amaranth grain have been found in Antofagasta de la Sierra Department, Catamarca, Argentina in the southern Puna desert of the north of Argentina dating from 4,500 years ago, with evidence suggesting earlier use. Archeological evidence of seeds from A. hypochondriacus and A. cruentus found in a cave in Tehuacán, Mexico, suggests amaranth was part of Aztec civilization in the 1400s.
Ancient amaranth grains still used include the three species Amaranthus caudatus, A. cruentus, and A. hypochondriacus. Evidence from single-nucleotide polymorphisms and chromosome structure supports A. hypochondriacus as the common ancestor of the three grain species. | Amaranth | Wikipedia | 382 | 1542 | https://en.wikipedia.org/wiki/Amaranth | Biology and health sciences | Caryophyllales | null |
It has been proposed as an inexpensive native crop that could be cultivated by indigenous people in rural areas for several reasons:
A small amount of seed plants a large area (seeding rate 1 kg/ha).
Yields are high compared to the seeding rate: 1,000 kg or more per hectare.
It is easily harvested and easily processed, post harvest, as there are no hulls to remove.
Its seeds are a source of protein.
It has rich content of the dietary minerals, calcium, magnesium, phosphorus, and potassium.
In cooked and edible forms, amaranth retains adequate content of several dietary minerals.
It is easy to cook. Boil in water with twice the amount of water as grain by volume (or 2.4 times as much water by weight). Amaranth seed can also be popped one tablespoon at a time in a hot pan without oil, shaken every few seconds to avoid burning.
It grows fast and, in three cultivated species, the large seedheads can weigh up to 1 kg and contain a half-million small seeds.
In the United States, the amaranth crop is mostly used for seed production. Most amaranth in American food products starts as a ground flour, blended with wheat or other flours to create cereals, crackers, cookies, bread or other baked products. Despite utilization studies showing that amaranth can be blended with other flours at levels above 50% without affecting functional properties or taste, most commercial products use amaranth only as a minor portion of their ingredients despite them being marketed as "amaranth" products.
Leaves, roots, and stems
Amaranth species are cultivated and consumed as a leaf vegetable in many parts of the world. Four species of Amaranthus are documented as cultivated vegetables in eastern Asia: Amaranthus cruentus, Amaranthus blitum, Amaranthus dubius, and Amaranthus tricolor.
Asia
In Indonesia and Malaysia, leaf amaranth is called (although the word has since been loaned to refer to spinach, in a different genus). In the Philippines, the Ilocano word for the plant is ; the Tagalog word for the plant is or . | Amaranth | Wikipedia | 447 | 1542 | https://en.wikipedia.org/wiki/Amaranth | Biology and health sciences | Caryophyllales | null |
In Uttar Pradesh and Bihar in India, it is called and is a popular red leafy vegetable (referred to in the class of vegetable preparations called ). It is called chua in Kumaun area of Uttarakhand, where it is a popular red-green vegetable. In Karnataka in India, it is called (). It is used to prepare curries such as hulee, palya, majjigay-hulee, and so on. In Kerala, it is called cheera and is consumed by stir-frying the leaves with spices and red chili peppers to make a dish called cheera thoran. In Tamil Nadu, it is called and is regularly consumed as a favourite dish, where the greens are steamed and mashed with light seasoning of salt, red chili pepper, and cumin. It is called . In the states of Andhra Pradesh and Telangana and other Telugu speaking regions of the country, this leaf is called as "Thotakura" and is cooked as a standalone curry, added as a part of mix leafy vegetable curry or added in preparation of a popular dal called () in (Telugu). In Maharashtra, it is called and is available in both red and white colour. In Orissa, it is called , it is used to prepare , in which the leaf is fried with chili and onions. In West Bengal, the green variant is called () and the red variant is called ().
In China, the leaves and stems are used as a stir-fry vegetable, or in soups. In Vietnam, it is called and is used to make soup. Two species are popular as edible vegetable in Vietnam: (Amaranthus tricolor) and or (Amaranthus viridis).
Africa
A traditional food plant in Africa, amaranth has the potential to improve nutrition, boost food security, foster rural development and support sustainable land care. | Amaranth | Wikipedia | 386 | 1542 | https://en.wikipedia.org/wiki/Amaranth | Biology and health sciences | Caryophyllales | null |
In Bantu regions of Uganda and western Kenya, it is known as doodo or litoto. It is also known among the Kalenjin as a drought crop (chepkerta). In Lingala (spoken in the Congo), it is known as or . In Nigeria, it is a common vegetable and goes with all Nigerian starch dishes. It is known in Yoruba as , a short form of (meaning "make the husband fat"), or (meaning "we have money left over for fish"). In Botswana, it is referred to as morug and cooked as a staple green vegetable.
Europe
In Greece, purple amaranth (Amaranthus blitum) is a popular dish called , or . It is boiled, then served with olive oil and lemon juice like a salad, sometimes alongside fried fish. Greeks stop harvesting the plant (which also grows wild) when it starts to bloom at the end of August.
Americas
In Brazil, green amaranth was, and to a degree still is, often considered an invasive species as all other species of amaranth (except the generally imported A. caudatus cultivar), though some have traditionally appreciated it as a leaf vegetable, under the names of or , which is consumed cooked, generally accompanying the staple food, rice and beans.
In the Caribbean, the leaves are called bhaji in Trinidad and callaloo in Jamaica, and are sautéed with onions, garlic, and tomatoes, or sometimes used in a soup called pepperpot soup.
Oil
Making up about 5% of the total fatty acids of amaranth, squalene is extracted as a vegetable-based alternative to the more expensive shark oil for use in dietary supplements and cosmetics.
Dyes
The flowers of the 'Hopi Red Dye' amaranth were used by the Hopi (a tribe in the western United States) as the source of a deep red dye. Also a synthetic dye was named "amaranth" for its similarity in color to the natural amaranth pigments known as betalains. This synthetic dye is also known as Red No. 2 in North America and E123 in the European Union.
Ornamentals | Amaranth | Wikipedia | 450 | 1542 | https://en.wikipedia.org/wiki/Amaranth | Biology and health sciences | Caryophyllales | null |
The genus also contains several well-known ornamental plants, such as Amaranthus caudatus (love-lies-bleeding), a vigorous, hardy annual with dark purplish flowers crowded in handsome drooping spikes. Another Indian annual, A. hypochondriacus (prince's feather), has deeply veined, lance-shaped leaves, purple on the under face, and deep crimson flowers densely packed on erect spikes.
Amaranths are recorded as food plants for some Lepidoptera (butterfly and moth) species including the nutmeg moth and various case-bearer moths of the genus Coleophora: C. amaranthella, C. enchorda (feeds exclusively on Amaranthus), C. immortalis (feeds exclusively on Amaranthus), C. lineapulvella, and C. versurella (recorded on A. spinosus).
Culture
Diego Durán described the festivities for the Aztec god . The Aztec month of (7 December to 26 December) was dedicated to . People decorated their homes and trees with paper flags; ritual races, processions, dances, songs, prayers, and finally human sacrifices were held. This was one of the more important Aztec festivals, and the people prepared for the whole month. They fasted or ate very little; a statue of the god was made out of amaranth seeds and honey, and at the end of the month, it was cut into small pieces so everybody could eat a piece of the god. After the Spanish conquest, cultivation of amaranth was outlawed, while some of the festivities were subsumed into the Christmas celebration.
Amaranth is associated with longevity and, poetically, with death and immortality. Amaranth garlands were used in the mourning of Achilles.
John Milton's Paradise Lost portrays a showy amaranth in the Garden of Eden, "remov'd from Heav'n" when it blossoms because the flowers "shade the fountain of life". He describes amaranth as "immortal" in reference to the flowers that generally do not wither and retain bright reddish tones of color, even when deceased; referred to in one species as "love-lies-bleeding."
Gallery | Amaranth | Wikipedia | 458 | 1542 | https://en.wikipedia.org/wiki/Amaranth | Biology and health sciences | Caryophyllales | null |
Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. lotus). Aquaculture involves cultivating freshwater, brackish water, and saltwater populations under controlled or semi-natural conditions and can be contrasted with commercial fishing, which is the harvesting of wild fish. Aquaculture is also a practice used for restoring and rehabilitating marine and freshwater ecosystems. Mariculture, commonly known as marine farming, is aquaculture in seawater habitats and lagoons, as opposed to freshwater aquaculture. Pisciculture is a type of aquaculture that consists of fish farming to obtain fish products as food.
Aquaculture can also be defined as the breeding, growing, and harvesting of fish and other aquatic plants, also known as farming in water. It is an environmental source of food and commercial products that help to improve healthier habitats and are used to reconstruct the population of endangered aquatic species. Technology has increased the growth of fish in coastal marine waters and open oceans due to the increased demand for seafood.
Aquaculture can be conducted in completely artificial facilities built on land (onshore aquaculture), as in the case of fish tank, ponds, aquaponics or raceways, where the living conditions rely on human control such as water quality (oxygen), feed, temperature. Alternatively, they can be conducted on well-sheltered shallow waters nearshore of a body of water (inshore aquaculture), where the cultivated species are subjected to relatively more naturalistic environments; or on fenced/enclosed sections of open water away from the shore (offshore aquaculture), where the species are either cultured in cages, racks or bags and are exposed to more diverse natural conditions such as water currents (such as ocean currents), diel vertical migration and nutrient cycles. | Aquaculture | Wikipedia | 403 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
According to the Food and Agriculture Organization (FAO), aquaculture "is understood to mean the farming of aquatic organisms including fish, molluscs, crustaceans and aquatic plants. Farming implies some form of intervention in the rearing process to enhance production, such as regular stocking, feeding, protection from predators, etc. Farming also implies individual or corporate ownership of the stock being cultivated." The reported output from global aquaculture operations in 2019 was over 120 million tonnes valued at US$274 billion, by 2022, it had risen to 130.9 million tonnes, valued at USD 312.8 billion. However, there are issues with the reliability of the reported figures. Further, in current aquaculture practice, products from several kilograms of wild fish are used to produce one kilogram of a piscivorous fish like salmon. Plant and insect-based feeds are also being developed to help reduce wild fish been used for aquaculture feed.
Particular kinds of aquaculture include fish farming, shrimp farming, oyster farming, mariculture, pisciculture, algaculture (such as seaweed farming), and the cultivation of ornamental fish. Particular methods include aquaponics and integrated multi-trophic aquaculture, both of which integrate fish farming and aquatic plant farming. The FAO describes aquaculture as one of the industries most directly affected by climate change and its impacts. Some forms of aquaculture have negative impacts on the environment, such as through nutrient pollution or disease transfer to wild populations.
Overview
Harvest stagnation in wild fisheries and overexploitation of popular marine species, combined with a growing demand for high-quality protein, encouraged aquaculturists to domesticate other marine species. At the outset of modern aquaculture, many were optimistic that a "Blue Revolution" could take place in aquaculture, just as the Green Revolution of the 20th century had revolutionized agriculture. Although land animals had long been domesticated, most seafood species were still caught from the wild. Concerned about the impact of growing demand for seafood on the world's oceans, prominent ocean explorer Jacques Cousteau wrote in 1973: "With earth's burgeoning human populations to feed, we must turn to the sea with new understanding and new technology." | Aquaculture | Wikipedia | 460 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
About 430 (97%) of the species cultured were domesticated during the 20th and 21st centuries, of which an estimated 106 came in the decade to 2007. Given the long-term importance of agriculture, to date, only 0.08% of known land plant species and 0.0002% of known land animal species have been domesticated, compared with 0.17% of known marine plant species and 0.13% of known marine animal species. Domestication typically involves about a decade of scientific research. Domesticating aquatic species involves fewer risks to humans than do land animals, which took a large toll in human lives. Most major human diseases originated in domesticated animals, including diseases such as smallpox and diphtheria, that like most infectious diseases, move to humans from animals. No human pathogens of comparable virulence have yet emerged from marine species.
Biological control methods to manage parasites are already being used, such as cleaner fish (e.g. lumpsuckers and wrasse) to control sea lice populations in salmon farming. Models are being used to help with spatial planning and siting of fish farms in order to minimize impact.
The decline in wild fish stocks has increased the demand for farmed fish. However, finding alternative sources of protein and oil for fish feed is necessary so the aquaculture industry can grow sustainably; otherwise, it represents a great risk for the over-exploitation of forage fish.
Aquaculture production now exceeds capture fishery production and together the relative GDP contribution has ranged from 0.01 to 10%. Singling out aquaculture's relative contribution to GDP, however, is not easily derived due to lack of data.
Another recent issue following the banning in 2008 of organotins by the International Maritime Organization is the need to find environmentally friendly, but still effective, compounds with antifouling effects.
Many new natural compounds are discovered every year, but producing them on a large enough scale for commercial purposes is almost impossible.
It is highly probable that future developments in this field will rely on microorganisms, but greater funding and further research is needed to overcome the lack of knowledge in this field.
Species groups
Aquatic plants | Aquaculture | Wikipedia | 440 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Microalgae, also referred to as phytoplankton, microphytes, or planktonic algae, constitute the majority of cultivated algae. Macroalgae commonly known as seaweed also have many commercial and industrial uses, but due to their size and specific requirements, they are not easily cultivated on a large scale and are most often taken in the wild.
In 2016, aquaculture was the source of 96.5 percent by volume of the total 31.2 million tonnes of wild-collected and cultivated aquatic plants combined. Global production of farmed aquatic plants, overwhelmingly dominated by seaweeds, grew in output volume from 13.5 million tonnes in 1995 to just over 30 million tonnes in 2016.
Seaweed farming
Fish
The farming of fish is the most common form of aquaculture. It involves raising fish commercially in tanks, fish ponds, or ocean enclosures, usually for food. A facility that releases juvenile fish into the wild for recreational fishing or to supplement a species' natural numbers is generally referred to as a fish hatchery. Worldwide, the most important fish species used in fish farming are, in order, carp, salmon, tilapia, and catfish.
In the Mediterranean, young bluefin tuna are netted at sea and towed slowly towards the shore. They are then interned in offshore pens (sometimes made from floating HDPE pipe) where they are further grown for the market. In 2009, researchers in Australia managed for the first time to coax southern bluefin tuna to breed in landlocked tanks. Southern bluefin tuna are also caught in the wild and fattened in grow-out sea cages in southern Spencer Gulf, South Australia.
A similar process is used in the salmon-farming section of this industry; juveniles are taken from hatcheries and a variety of methods are used to aid them in their maturation. For example, as stated above, some of the most important fish species in the industry, salmon, can be grown using a cage system. This is done by having netted cages, preferably in open water that has a strong flow, and feeding the salmon a special food mixture that aids their growth. This process allows for year-round growth of the fish, thus a higher harvest during the correct seasons. An additional method, known sometimes as sea ranching, has also been used within the industry. Sea ranching involves raising fish in a hatchery for a brief time and then releasing them into marine waters for further development, whereupon the fish are recaptured when they have matured. | Aquaculture | Wikipedia | 511 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Crustaceans
Commercial shrimp farming began in the 1970s, and production grew steeply thereafter. Global production reached more than 1.6 million tonnes in 2003, worth about US$9 billion. About 75% of farmed shrimp is produced in Asia, in particular in China and Thailand. The other 25% is produced mainly in Latin America, where Brazil is the largest producer. Thailand is the largest exporter.
Shrimp farming has changed from its traditional, small-scale form in Southeast Asia into a global industry. Technological advances have led to ever higher densities per unit area, and broodstock is shipped worldwide. Virtually all farmed shrimp are penaeids (i.e., shrimp of the family Penaeidae), and just two species of shrimp, the Pacific white shrimp and the giant tiger prawn, account for about 80% of all farmed shrimp. These industrial monocultures are very susceptible to disease, which has decimated shrimp populations across entire regions. Increasing ecological problems, repeated disease outbreaks, and pressure and criticism from both nongovernmental organizations and consumer countries led to changes in the industry in the late 1990s and generally stronger regulations. In 1999, governments, industry representatives, and environmental organizations initiated a program aimed at developing and promoting more sustainable farming practices through the Seafood Watch program.
Freshwater prawn farming shares many characteristics with, including many problems with, marine shrimp farming. Unique problems are introduced by the developmental lifecycle of the main species, the giant river prawn.
The global annual production of freshwater prawns (excluding crayfish and crabs) in 2007 was about 460,000 tonnes, exceeding 1.86 billion dollars. Additionally, China produced about 370,000 tonnes of Chinese river crab.
In addition astaciculture is the freshwater farming of crayfish (mostly in the US, Australia, and Europe).
Molluscs
Aquacultured shellfish include various oyster, mussel, and clam species. These bivalves are filter and/or deposit feeders, which rely on ambient primary production rather than inputs of fish or other feed. As such, shellfish aquaculture is generally perceived as benign or even beneficial.
Depending on the species and local conditions, bivalve molluscs are either grown on the beach, on longlines, or suspended from rafts and harvested by hand or by dredging. In May 2017 a Belgian consortium installed the first of two trial mussel farms on a wind farm in the North Sea. | Aquaculture | Wikipedia | 505 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Abalone farming began in the late 1950s and early 1960s in Japan and China. Since the mid-1990s, this industry has become increasingly successful. Overfishing and poaching have reduced wild populations to the extent that farmed abalone now supplies most abalone meat. Sustainably farmed molluscs can be certified by Seafood Watch and other organizations, including the World Wildlife Fund (WWF). WWF initiated the "Aquaculture Dialogues" in 2004 to develop measurable and performance-based standards for responsibly farmed seafood. In 2009, WWF co-founded the Aquaculture Stewardship Council with the Dutch Sustainable Trade Initiative to manage the global standards and certification programs.
After trials in 2012, a commercial "sea ranch" was set up in Flinders Bay, Western Australia, to raise abalone. The ranch is based on an artificial reef made up of 5000 () separate concrete units called abitats (abalone habitats). The 900 kg abitats can host 400 abalone each. The reef is seeded with young abalone from an onshore hatchery. The abalone feed on seaweed that has grown naturally on the habitats, with the ecosystem enrichment of the bay also resulting in growing numbers of dhufish, pink snapper, wrasse, and Samson fish, among other species.
Brad Adams, from the company, has emphasised the similarity to wild abalone and the difference from shore-based aquaculture. "We're not aquaculture, we're ranching, because once they're in the water they look after themselves."
Other groups
Other groups include aquatic reptiles, amphibians, and miscellaneous invertebrates, such as echinoderms and jellyfish. They are separately graphed at the top right of this section, since they do not contribute enough volume to show clearly on the main graph.
Commercially harvested echinoderms include sea cucumbers and sea urchins. In China, sea cucumbers are farmed in artificial ponds as large as .
Global fish production | Aquaculture | Wikipedia | 410 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Global fish production peaked at about 171 million tonnes in 2016, with aquaculture representing 47 percent of the total and 53 percent if non-food uses (including reduction to fishmeal and fish oil) are excluded. With capture fishery production relatively static since the late 1980s, aquaculture has been responsible for the continuing growth in the supply of fish for human consumption. Global aquaculture production (including aquatic plants) in 2016 was 110.2 million tonnes, with the first-sale value estimated at US$244 billion. Three years later, in 2019 the reported output from global aquaculture operations was over 120 million tonnes valued at US$274 billion and by 2022 it had reached 130.9 million tonnes, valued at USD 312.8 billion. For the first time, aquaculture surpassed capture fisheries in aquatic animal production with 94.4 million tonnes, representing 51 percent of the world total and a record 57 percent of the production destined for human consumption.
In 2022 most aquaculture workers were in Asia (95%), followed by Africa (3%) and Latin America and the Caribbean (2%).
The contribution of aquaculture to the global production of capture fisheries and aquaculture combined has risen continuously, reaching 46.8 percent in 2016, up from 25.7 percent in 2000. With 5.8 percent annual growth rate during the period 2001–2016, aquaculture continues to grow faster than other major food production sectors, but it no longer has the high annual growth rates experienced in the 1980s and 1990s.
In 2012, the total world production of fisheries was 158 million tonnes, of which aquaculture contributed 66.6 million tonnes, about 42%. The growth rate of worldwide aquaculture has been sustained and rapid, averaging about 8% per year for over 30 years, while the take from wild fisheries has been essentially flat for the last decade. The aquaculture market reached $86 billion in 2009.
Aquaculture is an especially important economic activity in China. Between 1980 and 1997, the Chinese Bureau of Fisheries reports, aquaculture harvests grew at an annual rate of 16.7%, jumping from 1.9 million tonnes to nearly 23 million tonnes. In 2005, China accounted for 70% of world production. Aquaculture is also currently one of the fastest-growing areas of food production in the U.S. | Aquaculture | Wikipedia | 468 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
About 90% of all U.S. shrimp consumption is farmed and imported. In recent years, salmon aquaculture has become a major export in southern Chile, especially in Puerto Montt, Chile's fastest-growing city.
A United Nations report titled The State of the World Fisheries and Aquaculture released in May 2014 maintained fisheries and aquaculture support the livelihoods of some 60 million people in Asia and Africa. FAO estimates that in 2016, overall, women accounted for nearly 14 percent of all people directly engaged in the fisheries and aquaculture primary sector.
In 2021, global fish production reached 182 million tonnes, with approximately equal amounts coming from capture (91.2 million tonnes) and aquaculture (90.9 million tonnes). Aquaculture has experienced rapid growth in recent decades, increasing almost sevenfold from 1990 to 2021.
Over-reporting by China
China overwhelmingly dominates the world in reported aquaculture output, reporting a total output which is double that of the rest of the world put together. However, there are some historical issues with the accuracy of China's returns.
In 2001, scientists Reg Watson and Daniel Pauly expressed concerns that China was over reporting its catch from wild fisheries in the 1990s. They said that made it appear that the global catch since 1988 was increasing annually by 300,000 tonnes, whereas it was really shrinking annually by 350,000 tonnes. Watson and Pauly suggested this may have been related to Chinese policies where state entities that monitored the economy were also tasked with increasing output. Also, until more recently, the promotion of Chinese officials was based on production increases from their own areas.
China disputed this claim. The official Xinhua News Agency quoted Yang Jian, director general of the Agriculture Ministry's Bureau of Fisheries, as saying that China's figures were "basically correct". However, the FAO accepted there were issues with the reliability of China's statistical returns, and for a period treated data from China, including the aquaculture data, apart from the rest of the world.
Aquacultural methods
Mariculture | Aquaculture | Wikipedia | 412 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Mariculture is the cultivation of marine organisms in seawater, variously in sheltered coastal waters ("inshore"), open ocean ("offshore"), and on land ("onshore"). Farmed species include algae (from microalgae (such as phytoplankton) to macroalgae (such as seaweed); shellfish (such as shrimp), lobster, oysters), and clams, and marine finfish. Channel catfish (Ictalurus punctatus), hard clams (Mercenaria mercenaria) and Atlantic salmon (Salmo salar) are prominent in the U.S. mariculture.
Mariculture may consist of raising the organisms on or in artificial enclosures such as in floating netted enclosures for salmon, and on racks or in floating cages for oysters. In the case of enclosed salmon, they are fed by the operators; oysters on racks filter feed on naturally available food. Abalone have been farmed on an artificial reef consuming seaweed which grows naturally on the reef units.
Integrated
Integrated multi-trophic aquaculture (IMTA) is a practice in which the byproducts (wastes) from one species are recycled to become inputs (fertilizers, food) for another. Fed aquaculture (for example, fish, shrimp) is combined with inorganic extractive and organic extractive (for example, shellfish) aquaculture to create balanced systems for environmental sustainability (biomitigation), economic stability (product diversification and risk reduction) and social acceptability (better management practices). | Aquaculture | Wikipedia | 332 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
"Multi-trophic" refers to the incorporation of species from different trophic or nutritional levels in the same system. This is one potential distinction from the age-old practice of aquatic polyculture, which could simply be the co-culture of different fish species from the same trophic level. In this case, these organisms may all share the same biological and chemical processes, with few synergistic benefits, which could potentially lead to significant shifts in the ecosystem. Some traditional polyculture systems may, in fact, incorporate a greater diversity of species, occupying several niches, as extensive cultures (low intensity, low management) within the same pond. A working IMTA system can result in greater total production based on mutual benefits to the co-cultured species and improved ecosystem health, even if the production of individual species is lower than in a monoculture over a short-term period.
Sometimes the term "integrated aquaculture" is used to describe the integration of monocultures through water transfer. For all intents and purposes, however, the terms "IMTA" and "integrated aquaculture" differ only in their degree of descriptiveness. Aquaponics, fractionated aquaculture, integrated agriculture-aquaculture systems, integrated peri-urban-aquaculture systems, and integrated fisheries-aquaculture systems are other variations of the IMTA concept.
Urban aquaculture
Netting materials
Various materials, including nylon, polyester, polypropylene, polyethylene, plastic-coated welded wire, rubber, patented rope products (Spectra, Thorn-D, Dyneema), galvanized steel and copper are used for netting in aquaculture fish enclosures around the world. All of these materials are selected for a variety of reasons, including design feasibility, material strength, cost, and corrosion resistance.
Recently, copper alloys have become important netting materials in aquaculture because they are antimicrobial (i.e., they destroy bacteria, viruses, fungi, algae, and other microbes) and they therefore prevent biofouling (i.e., the undesirable accumulation, adhesion, and growth of microorganisms, plants, algae, tubeworms, barnacles, mollusks, and other organisms). By inhibiting microbial growth, copper alloy aquaculture cages avoid costly net changes that are necessary with other materials. The resistance of organism growth on copper alloy nets also provides a cleaner and healthier environment for farmed fish to grow and thrive. | Aquaculture | Wikipedia | 509 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Technology
Uncrewed vessels, like ROVs and AUVs, are now being used in aquaculture in various ways, such as site planning, cage or net inspection, environmental monitoring, disaster assessment, and risk reduction. The use of uncrewed vessels aims to increase safety, efficiency, and accuracy of aquaculture operations. Aquaculture is a multi-million-dollar business that relies on net and cage maintenance. Inspections used to be conducted by divers manually inspecting the nets, but uncrewed vessels are now being used to conduct faster and more efficient inspections.
Biofloc technology is also used to simultaneously improve water quality and generate bacterial biomass as food for the cultured animals.
Issues
If performed without consideration for potential local environmental impacts, aquaculture in inland waters can result in more environmental damage than wild fisheries, though with less waste produced per kg on a global scale. Local concerns with aquaculture in inland waters may include waste handling, side-effects of antibiotics, competition between farmed and wild animals, and the potential introduction of invasive plant and animal species, or foreign pathogens, particularly if unprocessed fish are used to feed more marketable carnivorous fish. If non-local live feeds are used, aquaculture may introduce exotic plants or animals with disastrous effects. Improvements in methods resulting from advances in research and the availability of commercial feeds has reduced some of these concerns since their greater prevalence in the 1990s and 2000s .
Fish waste is organic and composed of nutrients necessary in all components of aquatic food webs. In-ocean aquaculture often produces much higher than normal fish waste concentrations. The waste collects on the ocean bottom, damaging or eliminating bottom-dwelling life. Waste can also decrease dissolved oxygen levels in the water column, putting further pressure on wild animals. An alternative model to food being added to the ecosystem, is the installation of artificial reef structures to increase the habitat niches available, without the need to add any more than ambient feed and nutrient. This has been used in the "ranching" of abalone in Western Australia.
Impacts on wild fish
Some carnivorous and omnivorous farmed fish species are fed wild forage fish. Although carnivorous farmed fish represented only 13 percent of aquaculture production by weight in 2000, they represented 34 percent of aquaculture production by value. | Aquaculture | Wikipedia | 461 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Farming of carnivorous species like salmon and shrimp leads to a high demand for forage fish to match the nutrition they get in the wild. Fish do not actually produce omega-3 fatty acids, but instead accumulate them from either consuming microalgae that produce these fatty acids, as is the case with forage fish like herring and sardines, or, as is the case with fatty predatory fish, like salmon, by eating prey fish that have accumulated omega-3 fatty acids from microalgae. To satisfy this requirement, more than 50 percent of the world fish oil production is fed to farmed salmon.
Farmed salmon consume more wild fish than they generate as a final product, although the efficiency of production is improving. To produce one kilograms of farmed salmon, products from several kilograms of wild fish are fed to them – this can be described as the "fish-in-fish-out" (FIFO) ratio. In 1995, salmon had a FIFO ratio of 7.5 (meaning 7.5 kilograms of wild fish feed were required to produce one kilogram of salmon); by 2006 the ratio had fallen to 4.9. Additionally, a growing share of fish oil and fishmeal come from residues (byproducts of fish processing), rather than dedicated whole fish. In 2012, 34 percent of fish oil and 28 percent of fishmeal came from residues. However, fishmeal and oil from residues instead of whole fish have a different composition with more ash and less protein, which may limit its potential use for aquaculture.
As the salmon farming industry expands, it requires more wild forage fish for feed, at a time when seventy-five percent of the world's monitored fisheries are already near to or have exceeded their maximum sustainable yield. The industrial-scale extraction of wild forage fish for salmon farming then impacts the survivability of the wild predator fish who rely on them for food. An important step in reducing the impact of aquaculture on wild fish is shifting carnivorous species to plant-based feeds. Salmon feeds, for example, have gone from containing only fishmeal and oil to containing 40 percent plant protein. The USDA has also experimented with using grain-based feeds for farmed trout. When properly formulated (and often mixed with fishmeal or oil), plant-based feeds can provide proper nutrition and similar growth rates in carnivorous farmed fish. | Aquaculture | Wikipedia | 493 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Another impact aquaculture production can have on wild fish is the risk of fish escaping from coastal pens, where they can interbreed with their wild counterparts, diluting wild genetic stocks. Escaped fish can become invasive, out-competing native species.
Animal welfare
As with the farming of terrestrial animals, social attitudes influence the need for humane practices and regulations in farmed marine animals. Under the guidelines advised by the Farm Animal Welfare Council good animal welfare means both fitness and a sense of well-being in the animal's physical and mental state. This can be defined by the Five Freedoms:
Freedom from hunger and thirst
Freedom from discomfort
Freedom from pain, disease, or injury
Freedom to express normal behaviour
Freedom from fear and distress
However, the controversial issue in aquaculture is whether fish and farmed marine invertebrates are actually sentient, or have the perception and awareness to experience suffering. Although no evidence of this has been found in marine invertebrates, recent studies conclude that fish do have the necessary receptors (nociceptors) to sense noxious stimuli and so are likely to experience states of pain, fear and stress. Consequently, welfare in aquaculture is directed at vertebrates, finfish in particular.
Common welfare concerns
Welfare in aquaculture can be impacted by a number of issues such as stocking densities, behavioural interactions, disease and parasitism. A major problem in determining the cause of impaired welfare is that these issues are often all interrelated and influence each other at different times. | Aquaculture | Wikipedia | 299 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Optimal stocking density is often defined by the carrying capacity of the stocked environment and the amount of individual space needed by the fish, which is very species specific. Although behavioural interactions such as shoaling may mean that high stocking densities are beneficial to some species, in many cultured species high stocking densities may be of concern. Crowding can constrain normal swimming behaviour, as well as increase aggressive and competitive behaviours such as cannibalism, feed competition, territoriality and dominance/subordination hierarchies. This potentially increases the risk of tissue damage due to abrasion from fish-to-fish contact or fish-to-cage contact. Fish can suffer reductions in food intake and food conversion efficiency. In addition, high stocking densities can result in water flow being insufficient, creating inadequate oxygen supply and waste product removal. Dissolved oxygen is essential for fish respiration and concentrations below critical levels can induce stress and even lead to asphyxiation. Ammonia, a nitrogen excretion product, is highly toxic to fish at accumulated levels, particularly when oxygen concentrations are low.
Many of these interactions and effects cause stress in the fish, which can be a major factor in facilitating fish disease. For many parasites, infestation depends on the host's degree of mobility, the density of the host population and vulnerability of the host's defence system. Sea lice are the primary parasitic problem for finfish in aquaculture, high numbers causing widespread skin erosion and haemorrhaging, gill congestion, and increased mucus production. There are also a number of prominent viral and bacterial pathogens that can have severe effects on internal organs and nervous systems.
Improving welfare
The key to improving welfare of marine cultured organisms is to reduce stress to a minimum, as prolonged or repeated stress can cause a range of adverse effects. Attempts to minimise stress can occur throughout the culture process. Understanding and providing required environmental enrichment can be vital for reducing stress and benefit aquaculture objects such as improved growth body condition and reduced damage from aggression. During grow-out it is important to keep stocking densities at appropriate levels specific to each species, as well as separating size classes and grading to reduce aggressive behavioural interactions. Keeping nets and cages clean can assist positive water flow to reduce the risk of water degradation. | Aquaculture | Wikipedia | 471 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Not surprisingly disease and parasitism can have a major effect on fish welfare and it is important for farmers not only to manage infected stock but also to apply disease prevention measures. However, prevention methods, such as vaccination, can also induce stress because of the extra handling and injection. Other methods include adding antibiotics to feed, adding chemicals into water for treatment baths and biological control, such as using cleaner wrasse to remove lice from farmed salmon.
Many steps are involved in transport, including capture, food deprivation to reduce faecal contamination of transport water, transfer to transport vehicle via nets or pumps, plus transport and transfer to the delivery location. During transport water needs to be maintained to a high quality, with regulated temperature, sufficient oxygen and minimal waste products. In some cases anaesthetics may be used in small doses to calm fish before transport.
Aquaculture is sometimes part of an environmental rehabilitation program or as an aid in conserving endangered species.
Coastal ecosystems
Aquaculture is becoming a significant threat to coastal ecosystems. About 20 percent of mangrove forests have been destroyed since 1980, partly due to shrimp farming. An extended cost–benefit analysis of the total economic value of shrimp aquaculture built on mangrove ecosystems found that the external costs were much higher than the external benefits. Over four decades, of Indonesian mangroves have been converted to shrimp farms. Most of these farms are abandoned within a decade because of the toxin build-up and nutrient loss.
Pollution from sea cage aquaculture
Salmon farms are typically sited in pristine coastal ecosystems which they then pollute. A farm with 200,000 salmon discharges more fecal waste than a city of 60,000 people. This waste is discharged directly into the surrounding aquatic environment, untreated, often containing antibiotics and pesticides." There is also an accumulation of heavy metals on the benthos (seafloor) near the salmon farms, particularly copper and zinc.
In 2016, mass fish kill events impacted salmon farmers along Chile's coast and the wider ecology. Increases in aquaculture production and its associated effluent were considered to be possible contributing factors to fish and molluscan mortality. | Aquaculture | Wikipedia | 432 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Sea cage aquaculture is responsible for nutrient enrichment of the waters in which they are established. This results from fish wastes and uneaten feed inputs. Elements of most concern are nitrogen and phosphorus which can promote algal growth, including harmful algal blooms which can be toxic to fish. Flushing times, current speeds, distance from the shore and water depth are important considerations when locating sea cages in order to minimize the impacts of nutrient enrichment on coastal ecosystems.
The extent of the effects of pollution from sea-cage aquaculture varies depending on where the cages are located, which species are kept, how densely cages are stocked and what the fish are fed. Important species-specific variables include the species' food conversion ratio (FCR) and nitrogen retention.
Freshwater ecosystems
Whole-lake experiments carried out at the Experimental Lakes Area in Ontario, Canada, have displayed the potential for cage aquaculture to source numerous changes in freshwater ecosystems. Following the initiation of an experimental rainbow trout cage farm in a small boreal lake, dramatic reductions in mysis concentrations associated with a decrease in dissolved oxygen were observed. Significant increases in ammonium and total phosphorus, a driver for eutrophication in freshwater systems, were measured in the hypolimnion of the lake. Annual phosphorus inputs from aquaculture waste exceeded that of natural inputs from atmospheric deposition and inflows, and phytoplankton biomass has had a fourfold annual increase following the initiation of the experimental farm.
Genetic modification
A type of salmon called the AquAdvantage salmon has been genetically modified for faster growth, although it has not been approved for commercial use, due to controversy. The altered salmon incorporates a growth hormone from a Chinook salmon that allows it to reach full size in 16–28 months, instead of the normal 36 months for Atlantic salmon, and while consuming 25 percent less feed. The U.S. Food and Drug Administration reviewed the AquAdvantage salmon in a draft environmental assessment and determined that it "would not have a significant impact (FONSI) on the U.S. environment."
Fish diseases, parasites and vaccines
A major difficulty for aquaculture is the tendency towards monoculture and the associated risk of widespread disease. Aquaculture is also associated with environmental risks; for instance, shrimp farming has caused the destruction of important mangrove forests throughout southeast Asia.
In the 1990s, disease wiped out China's farmed Farrer's scallop and white shrimp and required their replacement by other species. | Aquaculture | Wikipedia | 500 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Needs of the aquaculture sector in vaccines
Aquaculture has an average annual growth rate of 9.2%, however, the success and continued expansion of the fish farming sector is highly dependent on the control of fish pathogens including a wide range of viruses, bacteria, fungi, and parasites. In 2014, it was estimated that these parasites cost the global salmon farming industry up to 400 million Euros. This represents 6–10% of the production value of the affected countries, but it can go up to 20% (Fisheries and Oceans Canada, 2014). Since pathogens quickly spread within a population of cultured fish, their control is vital for the sector.
Historically, the use of antibiotics was against bacterial epizootics but the production of animal proteins has to be sustainable, which means that preventive measures that are acceptable from a biological and environmental point of view should be used to keep disease problems in aquaculture at an acceptable level. So, this added to the efficiency of vaccines resulted in an immediate and permanent reduction in the use of antibiotics in the 90s. In the beginning, there were fish immersion vaccines efficient against the vibriosis but proved ineffective against the furunculosis, hence the arrival of injectable vaccines: first water-based and after oil-based, much more efficient (Sommerset, 2005). | Aquaculture | Wikipedia | 269 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Development of new vaccines
It is the important mortality in cages among farmed fish, the debates around DNA injection vaccines, although effective, their safety and their side effects but also societal expectations for cleaner fish and security, lead research on new vaccine vectors. Several initiatives are financed by the European Union to develop a rapid and cost-effective approach to using bacteria in feed to make vaccines, in particular thanks to lactic bacteria whose DNA is modified (Boudinot, 2006). In fact, vaccinating farmed fish by injection is time-consuming and costly, so vaccines can be administered orally or by immersion by being added to feed or directly into water. This allows vaccinating many individuals at the same time while limiting the associated handling and stress.
Indeed, many tests are necessary because the antigens of the vaccines must be adapted to each species or not present a certain level of variability or they will not have any effect. For example, tests have been done with two species: Lepeophtheirus salmonis (from which the antigens were collected) and Caligus rogercresseyi (which was vaccinated with the antigens), although the homology between the two species is important, the level of variability made the protection ineffective (Fisheries and Oceans Canada, 2014). | Aquaculture | Wikipedia | 264 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Recent vaccines development in aquaculture
There are 24 vaccines available and one for lobsters. The first vaccine was used in the USA against enteric red mouth in 1976. However, there are 19 companies and some small stakeholders are producing vaccines for aquaculture nowadays. The novel approaches are a way forward to prevent the loss of 10% of aquaculture through disease. Genetically modified vaccines are not being used in the EU due to societal concerns and regulations. Meanwhile, DNA vaccines are now authorised in the EU.
There are challenges in fish vaccine development, immune response due to lack of potent adjuvants. Scientists are considering microdose application in future. But there are also opportunities in aquaculture vaccinology due to the low cost of technology, regulations change and novel antigen expression and delivery systems.
In Norway subunit vaccine (VP2 peptide) against infectious pancreatic necrosis is being used. In Canada, a licensed DNA vaccine against Infectious hematopoietic necrosis has been launched for industry use.
Fish have large mucosal surfaces, so the preferred route is immersion, intraperitoneal and oral respectively. Nanoparticles are in progress for delivery purposes. The common antibodies produced are IgM and IgT. Normally booster is not required in fish because more memory cells are produced in response to the booster rather than an increased level of antibodies.
mRNA vaccines are alternative to DNA vaccines because they are more safe, stable, easily producible at a large scale and mass immunization potential. Recently these are used in cancer prevention and therapeutics. Studies in rabies has shown that efficacy depends on dose and route of administration. These are still in infancy.
Economic gains
In 2014, the aquaculture produced fish overtook wild caught fish, in supply for human food. This means there is a huge demand for vaccines, in prevention of diseases. The reported annual loss fish, calculates to >10 billion USD. This is from approximately 10% of all fishes dying from infectious diseases.
The high annual losses increases the demand for vaccines. Even though there are about 24 traditionally used vaccines, there is still demand for more vaccines. The breakthrough of DNA-vaccines has sunk the cost of vaccines.
The alternative to vaccines would be antibiotics and chemotherapy, which are more expensive and with bigger drawbacks. DNA-vaccines have become the most cost-efficient method of preventing infectious diseases. This bodes well for DNA-vaccines becoming the new standard both in fish vaccines, and in general vaccines. | Aquaculture | Wikipedia | 500 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Salinization/acidification of soils
Sediment from abandoned aquaculture farms can remain hypersaline, acidic and eroded. This material can remain unusable for aquaculture purposes for long periods thereafter. Various chemical treatments, such as adding lime, can aggravate the problem by modify the physicochemical characteristics of the sediment.
Plastic pollution
Aquaculture produces a range of marine debris, depending on the product and location. The most frequently documented type of plastic is expanded polystyrene (EPS), used extensively in floats and sea cage collars (MEPC 2020). Other common waste items include cage nets and plastic harvest bins. A review of aquaculture as a source of marine litter in the North, Baltic and Mediterranean Seas identified 64 different items, 19 of which were unique to aquaculture . Estimates of the amount of aquaculture waste entering the oceans vary widely, depending on the methodologies used. For example, in the European Economic Area loss estimates have varied from a low of 3,000 tonnes to 41,000 tonnes per year.
Ecological benefits
While some forms of aquaculture can be devastating to ecosystems, such as shrimp farming in mangroves, other forms can be beneficial. Shellfish aquaculture adds substantial filter feeding capacity to an environment which can significantly improve water quality. A single oyster can filter 15 gallons of water a day, removing microscopic algal cells. By removing these cells, shellfish are removing nitrogen and other nutrients from the system and either retaining it or releasing it as waste which sinks to the bottom. By harvesting these shellfish, the nitrogen they retained is completely removed from the system. Raising and harvesting kelp and other macroalgae directly remove nutrients such as nitrogen and phosphorus. Repackaging these nutrients can relieve eutrophic, or nutrient-rich, conditions known for their low dissolved oxygen which can decimate species diversity and abundance of marine life. Removing algal cells from the water also increases light penetration, allowing plants such as eelgrass to reestablish themselves and further increase oxygen levels. | Aquaculture | Wikipedia | 410 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Aquaculture in an area can provide for crucial ecological functions for the inhabitants. Shellfish beds or cages can provide habitat structure. This structure can be used as shelter by invertebrates, small fish or crustaceans to potentially increase their abundance and maintain biodiversity. Increased shelter raises stocks of prey fish and small crustaceans by increasing recruitment opportunities in turn providing more prey for higher trophic levels. One study estimated that 10 square meters of oyster reef could enhance an ecosystem's biomass by 2.57 kg Herbivore shellfish will also be preyed on. This moves energy directly from primary producers to higher trophic levels potentially skipping out on multiple energetically costly trophic jumps which would increase biomass in the ecosystem.
Seaweed farming is a carbon negative crop, with a high potential for climate change mitigation. The IPCC Special Report on the Ocean and Cryosphere in a Changing Climate recommends "further research attention" as a mitigation tactic. Regenerative ocean farming is a polyculture farming system that grows a mix of seaweeds and shellfish while sequestering carbon, decreasing nitrogen in the water and increasing oxygen, helping to regenerate and restore local habitat like reef ecosystems.
Prospects
Global wild fisheries are in decline, with valuable habitat such as estuaries in critical condition. The aquaculture or farming of piscivorous fish, like salmon, does not help the problem because they need to eat products from other fish, such as fish meal and fish oil. Studies have shown that salmon farming has major negative impacts on wild salmon, as well as the forage fish that need to be caught to feed them. Fish that are higher on the food chain are less efficient sources of food energy.
Apart from fish and shrimp, some aquaculture undertakings, such as seaweed and filter-feeding bivalve mollusks like oysters, clams, mussels and scallops, are relatively benign and even environmentally restorative. Filter-feeders filter pollutants as well as nutrients from the water, improving water quality. Seaweeds extract nutrients such as inorganic nitrogen and phosphorus directly from the water, and filter-feeding mollusks can extract nutrients as they feed on particulates, such as phytoplankton and detritus. | Aquaculture | Wikipedia | 462 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Some profitable aquaculture cooperatives promote sustainable practices. New methods lessen the risk of biological and chemical pollution through minimizing fish stress, fallowing netpens, and applying integrated pest management. Vaccines are being used more and more to reduce antibiotic use for disease control.
Onshore recirculating aquaculture systems, facilities using polyculture techniques, and properly sited facilities (for example, offshore areas with strong currents) are examples of ways to manage negative environmental effects.
Recirculating aquaculture systems (RAS) recycle water by circulating it through filters to remove fish waste and food and then recirculating it back into the tanks. This saves water and the waste gathered can be used in compost or, in some cases, could even be treated and used on land. While RAS was developed with freshwater fish in mind, scientists associated with the Agricultural Research Service have found a way to rear saltwater fish using RAS in low-salinity waters. Although saltwater fish are raised in off-shore cages or caught with nets in water that typically has a salinity of 35 parts per thousand (ppt), scientists were able to produce healthy pompano, a saltwater fish, in tanks with a salinity of only 5 ppt. Commercializing low-salinity RAS are predicted to have positive environmental and economical effects. Unwanted nutrients from the fish food would not be added to the ocean and the risk of transmitting diseases between wild and farm-raised fish would greatly be reduced. The price of expensive saltwater fish, such as the pompano and cobia used in the experiments, would be reduced. However, before any of this can be done researchers must study every aspect of the fish's lifecycle, including the amount of ammonia and nitrate the fish will tolerate in the water, what to feed the fish during each stage of its lifecycle, the stocking rate that will produce the healthiest fish, etc.
Some 16 countries now use geothermal energy for aquaculture, including China, Israel, and the United States. In California, for example, 15 fish farms produce tilapia, bass, and catfish with warm water from underground. This warmer water enables fish to grow all year round and mature more quickly. Collectively these California farms produce 4.5 million kilograms of fish each year. | Aquaculture | Wikipedia | 474 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Global goals
The UN Sustainable Development Goal 14 ("life below water"), Target 14.7 includes aquaculture: "By 2030, increase the economic benefits to small island developing states and least developed countries from the sustainable use of marine resources, including through sustainable management of fisheries, aquaculture and tourism". Aquaculture's contribution to GDP is not included in SDG Target 14.7 but methods for quantifying this have been explored by FAO.
National laws, regulations, and management
Laws governing aquaculture practices vary greatly by country and are often not closely regulated or easily traceable.
In the United States, land-based and nearshore aquaculture is regulated at the federal and state levels; however, no national laws govern offshore aquaculture in U.S. exclusive economic zone waters. In June 2011, the Department of Commerce and National Oceanic and Atmospheric Administration released national aquaculture policies to address this issue and "to meet the growing demand for healthy seafood, to create jobs in coastal communities, and restore vital ecosystems." Large aquaculture facilities (i.e. those producing per year) which discharge wastewater are required to obtain permits pursuant to the Clean Water Act. Facilities that produce at least of fish, molluscs or crustaceans a year are subject to specific national discharge standards. Other permitted facilities are subject to effluent limitations that are developed on a case-by-case basis.
By country
Aquaculture by Country:
History
The Gunditjmara, a local Aboriginal Australian people in south-western Victoria, Australia, may have raised short-finned eels as early as about 4,580 BCE. Evidence indicates they developed about of volcanic floodplains in the vicinity of Lake Condah into a complex of channels and dams, and used woven traps to capture eels, and to preserve them to eat all year round. The local Budj Bim Cultural Landscape, a World Heritage Site, is one of the oldest known aquaculture sites in the world. | Aquaculture | Wikipedia | 400 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
Oral tradition in China tells of the culture of the common carp, Cyprinus carpio, as long ago as 2000–2100 BCE (around 4,000 years BP), but the earliest significant evidence lies in the literature, in the earliest monograph on fish culture called The Classic of Fish Culture, by Fan Li, written around 475 BCE ( BP). Another ancient Chinese guide to aquaculture , wriiten by Yang Yu Jing around 460 BCE, shows that carp farming was becoming more sophisticated. The Jiahu site in China has circumstantial archeological evidence as possibly the oldest aquaculture locations, dating from 6200BCE (about 8,200 years BP), but this is speculative. When the waters subsided after river floods, some fish, mainly carp, were trapped in lakes. Early aquaculturists fed their brood using nymphs and silkworm faeces, and ate them.
Ancient Egyptians might have farmed fish (especially gilt-head bream) from Lake Bardawil about 1,500 BCE (about 3,500 BP), and they traded them with Canaan.
Gim cultivation is the oldest aquaculture in Korea. Early cultivation methods used bamboo or oak sticks; newer methods utilizing nets replaced them in the 19th century. Floating rafts have been used for mass production since the 1920s.
Japanese people cultivated seaweed by providing bamboo poles and, later, nets and oyster shells to serve as anchoring-surfaces for spores.
Romans bred fish in ponds and farmed oysters in coastal lagoons before 100 CE.
In medieval Europe, early Christian monasteries adopted Roman aquacultural practices. Aquaculture spread because people away from coasts and big rivers were otherwise dependant on fish which required salting in order to be preserved. Fish was an important food source in medieval Europe, when in average 150 days per year were days of fasting and abstinence, and meat was prohibited. Improvements in transportation during the 19th century made fresh fish easily available and inexpensive, even in inland areas, rendering aquaculture less popular. The 15th-century fishponds of the Trebon Basin in the present-day Czech Republic are maintained as a tentative UNESCO World Heritage Site.
Samoans practised "a traditional form of giant clam ranching".
Hawaiians constructed oceanic fish ponds. A remarkable example is the "Menehune" fishpond dating from at least 1,000 years ago, at Alekoko. Legend records its construction by the mythical Menehune dwarf-people. | Aquaculture | Wikipedia | 508 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
In the first half of the 18th century, German Stephan Ludwig Jacobi experimented with external fertilization of brown trout and salmon. He wrote an article "" (On the Artificial Production of Trout and Salmon) summarizing his findings, and earning him a reputation as the founder of artificial fish-rearing. By the latter decades of the 18th century, oyster-farming had begun in estuaries along the Atlantic Coast of North America.
The word "aquaculture" appeared in an 1855 newspaper article in reference to the harvesting of ice. It also appeared in descriptions of the terrestrial agricultural practise of sub-irrigation in the late-19th century before becoming associated primarily with the cultivation of aquatic plant- and animal-species. (The Oxford English Dictionary records the common modern usage of "aquaculture" from 1887;
and that of "aquiculture" from 1867.)
In 1859, Stephen Ainsworth of West Bloomfield, New York, began experiments with brook trout. By 1864, Seth Green had established a commercial fish-hatching operation at Caledonia Springs, near Rochester, New York. By 1866, with the involvement of W. W. Fletcher of Concord, Massachusetts, artificial fish-hatcheries operated both in both Canada and in the United States. When the Dildo Island fish hatchery opened in Newfoundland in 1889, it was the largest and most advanced in the world. The word "aquaculture" was used in descriptions of the hatcheries experiments with cod and lobster in 1890.
By the 1920s, the American Fish Culture Company of Carolina, Rhode Island, founded in the 1870s, was one of the leading producers of trout. During the 1940s, they perfected the method of manipulating the day- and night-cycle of fish so that they could be artificially spawned year-round.
Californians harvested wild kelp and attempted to manage supply around 1900, later labeling it a wartime resource. | Aquaculture | Wikipedia | 381 | 1634 | https://en.wikipedia.org/wiki/Aquaculture | Technology | Forms | null |
In algorithmic information theory (a subfield of computer science and mathematics), the Kolmogorov complexity of an object, such as a piece of text, is the length of a shortest computer program (in a predetermined programming language) that produces the object as output. It is a measure of the computational resources needed to specify the object, and is also known as algorithmic complexity, Solomonoff–Kolmogorov–Chaitin complexity, program-size complexity, descriptive complexity, or algorithmic entropy. It is named after Andrey Kolmogorov, who first published on the subject in 1963 and is a generalization of classical information theory.
The notion of Kolmogorov complexity can be used to state and prove impossibility results akin to Cantor's diagonal argument, Gödel's incompleteness theorem, and Turing's halting problem.
In particular, no program P computing a lower bound for each text's Kolmogorov complexity can return a value essentially larger than P's own length (see section ); hence no single program can compute the exact Kolmogorov complexity for infinitely many texts. Kolmogorov complexity is the length of the ultimately compressed version of a file (i.e., anything which can be put in a computer). Formally, it is the length of a shortest program from which the file can be reconstructed. While Kolmogorov complexity is uncomputable, various approaches have been proposed and reviewed.
Definition
Intuition
Consider the following two strings of 32 lowercase letters and digits:
abababababababababababababababab , and
4c1j5b2p0cv4w1x8rx2y39umgw5q85s7
The first string has a short English-language description, namely "write ab 16 times", which consists of 17 characters. The second one has no obvious simple description (using the same character set) other than writing down the string itself, i.e., "write 4c1j5b2p0cv4w1x8rx2y39umgw5q85s7" which has 38 characters. Hence the operation of writing the first string can be said to have "less complexity" than writing the second. | Kolmogorov complexity | Wikipedia | 477 | 1635 | https://en.wikipedia.org/wiki/Kolmogorov%20complexity | Mathematics | Complexity theory | null |
More formally, the complexity of a string is the length of the shortest possible description of the string in some fixed universal description language (the sensitivity of complexity relative to the choice of description language is discussed below). It can be shown that the Kolmogorov complexity of any string cannot be more than a few bytes larger than the length of the string itself. Strings like the abab example above, whose Kolmogorov complexity is small relative to the string's size, are not considered to be complex.
The Kolmogorov complexity can be defined for any mathematical object, but for simplicity the scope of this article is restricted to strings. We must first specify a description language for strings. Such a description language can be based on any computer programming language, such as Lisp, Pascal, or Java. If P is a program which outputs a string x, then P is a description of x. The length of the description is just the length of P as a character string, multiplied by the number of bits in a character (e.g., 7 for ASCII).
We could, alternatively, choose an encoding for Turing machines, where an encoding is a function which associates to each Turing Machine M a bitstring <M>. If M is a Turing Machine which, on input w, outputs string x, then the concatenated string <M> w is a description of x. For theoretical analysis, this approach is more suited for constructing detailed formal proofs and is generally preferred in the research literature. In this article, an informal approach is discussed.
Any string s has at least one description. For example, the second string above is output by the pseudo-code:
function GenerateString2()
return "4c1j5b2p0cv4w1x8rx2y39umgw5q85s7"
whereas the first string is output by the (much shorter) pseudo-code:
function GenerateString1()
return "ab" × 16
If a description d(s) of a string s is of minimal length (i.e., using the fewest bits), it is called a minimal description of s, and the length of d(s) (i.e. the number of bits in the minimal description) is the Kolmogorov complexity of s, written K(s). Symbolically,
K(s) = |d(s)|. | Kolmogorov complexity | Wikipedia | 501 | 1635 | https://en.wikipedia.org/wiki/Kolmogorov%20complexity | Mathematics | Complexity theory | null |
The length of the shortest description will depend on the choice of description language; but the effect of changing languages is bounded (a result called the invariance theorem).
Plain Kolmogorov complexity C
There are two definitions of Kolmogorov complexity: plain and prefix-free. The plain complexity is the minimal description length of any program, and denoted while the prefix-free complexity is the minimal description length of any program encoded in a prefix-free code, and denoted . The plain complexity is more intuitive, but the prefix-free complexity is easier to study.
By default, all equations hold only up to an additive constant. For example, really means that , that is, .
Let be a computable function mapping finite binary strings to binary strings. It is a universal function if, and only if, for any computable , we can encode the function in a "program" , such that . We can think of as a program interpreter, which takes in an initial segment describing the program, followed by data that the program should process.
One problem with plain complexity is that , because intuitively speaking, there is no general way to tell where to divide an output string just by looking at the concatenated string. We can divide it by specifying the length of or , but that would take extra symbols. Indeed, for any there exists such that .
Typically, inequalities with plain complexity have a term like on one side, whereas the same inequalities with prefix-free complexity have only .
The main problem with plain complexity is that there is something extra sneaked into a program. A program not only represents for something with its code, but also represents its own length. In particular, a program may represent a binary number up to , simply by its own length. Stated in another way, it is as if we are using a termination symbol to denote where a word ends, and so we are not using 2 symbols, but 3. To fix this defect, we introduce the prefix-free Kolmogorov complexity. | Kolmogorov complexity | Wikipedia | 416 | 1635 | https://en.wikipedia.org/wiki/Kolmogorov%20complexity | Mathematics | Complexity theory | null |
Prefix-free Kolmogorov complexity K
A prefix-free code is a subset of such that given any two different words in the set, neither is a prefix of the other. The benefit of a prefix-free code is that we can build a machine that reads words from the code forward in one direction, and as soon as it reads the last symbol of the word, it knows that the word is finished, and does not need to backtrack or a termination symbol.
Define a prefix-free Turing machine to be a Turing machine that comes with a prefix-free code, such that the Turing machine can read any string from the code in one direction, and stop reading as soon as it reads the last symbol. Afterwards, it may compute on a work tape and write to a write tape, but it cannot move its read-head anymore.
This gives us the following formal way to describe K.
Fix a prefix-free universal Turing machine, with three tapes: a read tape infinite in one direction, a work tape infinite in two directions, and a write tape infinite in one direction.
The machine can read from the read tape in one direction only (no backtracking), and write to the write tape in one direction only. It can read and write the work tape in both directions.
The work tape and write tape start with all zeros. The read tape starts with an input prefix code, followed by all zeros.
Let be the prefix-free code on , used by the universal Turing machine.
Note that some universal Turing machines may not be programmable with prefix codes. We must pick only a prefix-free universal Turing machine.
The prefix-free complexity of a string is the shortest prefix code that makes the machine output :
Invariance theorem
Informal treatment
There are some description languages which are optimal, in the following sense: given any description of an object in a description language, said description may be used in the optimal description language with a constant overhead. The constant depends only on the languages involved, not on the description of the object, nor the object being described.
Here is an example of an optimal description language. A description will have two parts:
The first part describes another description language.
The second part is a description of the object in that language.
In more technical terms, the first part of a description is a computer program (specifically: a compiler for the object's language, written in the description language), with the second part being the input to that computer program which produces the object as output. | Kolmogorov complexity | Wikipedia | 512 | 1635 | https://en.wikipedia.org/wiki/Kolmogorov%20complexity | Mathematics | Complexity theory | null |
The invariance theorem follows: Given any description language L, the optimal description language is at least as efficient as L, with some constant overhead.
Proof: Any description D in L can be converted into a description in the optimal language by first describing L as a computer program P (part 1), and then using the original description D as input to that program (part 2). The
total length of this new description D′ is (approximately):
|D′ | = |P| + |D|
The length of P is a constant that doesn't depend on D. So, there is at most a constant overhead, regardless of the object described. Therefore, the optimal language is universal up to this additive constant.
A more formal treatment
Theorem: If K1 and K2 are the complexity functions relative to Turing complete description languages L1 and L2, then there is a constant c – which depends only on the languages L1 and L2 chosen – such that
∀s. −c ≤ K1(s) − K2(s) ≤ c.
Proof: By symmetry, it suffices to prove that there is some constant c such that for all strings s
K1(s) ≤ K2(s) + c.
Now, suppose there is a program in the language L1 which acts as an interpreter for L2:
function InterpretLanguage(string p)
where p is a program in L2. The interpreter is characterized by the following property:
Running InterpretLanguage on input p returns the result of running p.
Thus, if P is a program in L2 which is a minimal description of s, then InterpretLanguage(P) returns the string s. The length of this description of s is the sum of
The length of the program InterpretLanguage, which we can take to be the constant c.
The length of P which by definition is K2(s).
This proves the desired upper bound.
History and context
Algorithmic information theory is the area of computer science that studies Kolmogorov complexity and other complexity measures on strings (or other data structures). | Kolmogorov complexity | Wikipedia | 433 | 1635 | https://en.wikipedia.org/wiki/Kolmogorov%20complexity | Mathematics | Complexity theory | null |
The concept and theory of Kolmogorov Complexity is based on a crucial theorem first discovered by Ray Solomonoff, who published it in 1960, describing it in "A Preliminary Report on a General Theory of Inductive Inference" as part of his invention of algorithmic probability. He gave a more complete description in his 1964 publications, "A Formal Theory of Inductive Inference," Part 1 and Part 2 in Information and Control.
Andrey Kolmogorov later independently published this theorem in Problems Inform. Transmission in 1965. Gregory Chaitin also presents this theorem in J. ACM – Chaitin's paper was submitted October 1966 and revised in December 1968, and cites both Solomonoff's and Kolmogorov's papers.
The theorem says that, among algorithms that decode strings from their descriptions (codes), there exists an optimal one. This algorithm, for all strings, allows codes as short as allowed by any other algorithm up to an additive constant that depends on the algorithms, but not on the strings themselves. Solomonoff used this algorithm and the code lengths it allows to define a "universal probability" of a string on which inductive inference of the subsequent digits of the string can be based. Kolmogorov used this theorem to define several functions of strings, including complexity, randomness, and information.
When Kolmogorov became aware of Solomonoff's work, he acknowledged Solomonoff's priority. For several years, Solomonoff's work was better known in the Soviet Union than in the Western World. The general consensus in the scientific community, however, was to associate this type of complexity with Kolmogorov, who was concerned with randomness of a sequence, while Algorithmic Probability became associated with Solomonoff, who focused on prediction using his invention of the universal prior probability distribution. The broader area encompassing descriptional complexity and probability is often called Kolmogorov complexity. The computer scientist Ming Li considers this an example of the Matthew effect: "...to everyone who has, more will be given..."
There are several other variants of Kolmogorov complexity or algorithmic information. The most widely used one is based on self-delimiting programs, and is mainly due to Leonid Levin (1974).
An axiomatic approach to Kolmogorov complexity based on Blum axioms (Blum 1967) was introduced by Mark Burgin in the paper presented for publication by Andrey Kolmogorov. | Kolmogorov complexity | Wikipedia | 506 | 1635 | https://en.wikipedia.org/wiki/Kolmogorov%20complexity | Mathematics | Complexity theory | null |
In the late 1990s and early 2000s, methods developed to approximate Kolmogorov complexity relied on popular compression algorithms like LZW, which made difficult or impossible to provide any estimation to short strings until a method based on Algorithmic probability was introduced, offering the only alternative to compression-based methods.
Basic results
We write to be , where means some fixed way to code for a tuple of strings x and y.
Inequalities
We omit additive factors of . This section is based on.
Theorem.
Proof. Take any program for the universal Turing machine used to define plain complexity, and convert it to a prefix-free program by first coding the length of the program in binary, then convert the length to prefix-free coding. For example, suppose the program has length 9, then we can convert it as follows:where we double each digit, then add a termination code. The prefix-free universal Turing machine can then read in any program for the other machine as follows:The first part programs the machine to simulate the other machine, and is a constant overhead . The second part has length . The third part has length .
Theorem: There exists such that . More succinctly, . Similarly, , and .
Proof. For the plain complexity, just write a program that simply copies the input to the output. For the prefix-free complexity, we need to first describe the length of the string, before writing out the string itself.
Theorem. (extra information bounds, subadditivity)
Note that there is no way to compare and or or or . There are strings such that the whole string is easy to describe, but its substrings are very hard to describe.
Theorem. (symmetry of information) .
Proof. One side is simple. For the other side with , we need to use a counting argument (page 38 ).
Theorem. (information non-increase) For any computable function , we have .
Proof. Program the Turing machine to read two subsequent programs, one describing the function and one describing the string. Then run both programs on the work tape to produce , and write it out.
Uncomputability of Kolmogorov complexity
A naive attempt at a program to compute K
At first glance it might seem trivial to write a program which can compute K(s) for any s, such as the following: | Kolmogorov complexity | Wikipedia | 478 | 1635 | https://en.wikipedia.org/wiki/Kolmogorov%20complexity | Mathematics | Complexity theory | null |
function KolmogorovComplexity(string s)
for i = 1 to infinity:
for each string p of length exactly i
if isValidProgram(p) and evaluate(p) == s
return i
This program iterates through all possible programs (by iterating through all possible strings and only considering those which are valid programs), starting with the shortest. Each program is executed to find the result produced by that program, comparing it to the input s. If the result matches then the length of the program is returned.
However this will not work because some of the programs p tested will not terminate, e.g. if they contain infinite loops. There is no way to avoid all of these programs by testing them in some way before executing them due to the non-computability of the halting problem.
What is more, no program at all can compute the function K, be it ever so sophisticated. This is proven in the following.
Formal proof of uncomputability of K
Theorem: There exist strings of arbitrarily large Kolmogorov complexity. Formally: for each natural number n, there is a string s with K(s) ≥ n.
Proof: Otherwise all of the infinitely many possible finite strings could be generated by the finitely many programs with a complexity below n bits.
Theorem: K is not a computable function. In other words, there is no program which takes any string s as input and produces the integer K(s) as output.
The following proof by contradiction uses a simple Pascal-like language to denote programs; for sake of proof simplicity assume its description (i.e. an interpreter) to have a length of bits.
Assume for contradiction there is a program
function KolmogorovComplexity(string s)
which takes as input a string s and returns K(s). All programs are of finite length so, for sake of proof simplicity, assume it to be bits.
Now, consider the following program of length bits:
function GenerateComplexString()
for i = 1 to infinity:
for each string s of length exactly i
if KolmogorovComplexity(s) ≥ 8000000000
return s | Kolmogorov complexity | Wikipedia | 453 | 1635 | https://en.wikipedia.org/wiki/Kolmogorov%20complexity | Mathematics | Complexity theory | null |
Using KolmogorovComplexity as a subroutine, the program tries every string, starting with the shortest, until it returns a string with Kolmogorov complexity at least bits, i.e. a string that cannot be produced by any program shorter than bits. However, the overall length of the above program that produced s is only bits, which is a contradiction. (If the code of KolmogorovComplexity is shorter, the contradiction remains. If it is longer, the constant used in GenerateComplexString can always be changed appropriately.)
The above proof uses a contradiction similar to that of the Berry paradox: "The smallest positive integer that cannot be defined in fewer than twenty English words". It is also possible to show the non-computability of K by reduction from the non-computability of the halting problem H, since K and H are Turing-equivalent.
There is a corollary, humorously called the "full employment theorem" in the programming language community, stating that there is no perfect size-optimizing compiler.
Chain rule for Kolmogorov complexity
The chain rule for Kolmogorov complexity states that there exists a constant c such that for all X and Y:
K(X,Y) = K(X) + K(Y|X) + c*max(1,log(K(X,Y))).
It states that the shortest program that reproduces X and Y is no more than a logarithmic term larger than a program to reproduce X and a program to reproduce Y given X. Using this statement, one can define an analogue of mutual information for Kolmogorov complexity.
Compression
It is straightforward to compute upper bounds for K(s) – simply compress the string s with some method, implement the corresponding decompressor in the chosen language, concatenate the decompressor to the compressed string, and measure the length of the resulting string – concretely, the size of a self-extracting archive in the given language. | Kolmogorov complexity | Wikipedia | 423 | 1635 | https://en.wikipedia.org/wiki/Kolmogorov%20complexity | Mathematics | Complexity theory | null |
A string s is compressible by a number c if it has a description whose length does not exceed |s| − c bits. This is equivalent to saying that . Otherwise, s is incompressible by c. A string incompressible by 1 is said to be simply incompressible – by the pigeonhole principle, which applies because every compressed string maps to only one uncompressed string, incompressible strings must exist, since there are 2n bit strings of length n, but only 2n − 1 shorter strings, that is, strings of length less than n, (i.e. with length 0, 1, ..., n − 1).
For the same reason, most strings are complex in the sense that they cannot be significantly compressed – their K(s) is not much smaller than |s|, the length of s in bits. To make this precise, fix a value of n. There are 2n bitstrings of length n. The uniform probability distribution on the space of these bitstrings assigns exactly equal weight 2−n to each string of length n.
Theorem: With the uniform probability distribution on the space of bitstrings of length n, the probability that a string is incompressible by c is at least .
To prove the theorem, note that the number of descriptions of length not exceeding n − c is given by the geometric series:
1 + 2 + 22 + ... + 2n − c = 2n−c+1 − 1.
There remain at least
2n − 2n−c+1 + 1
bitstrings of length n that are incompressible by c. To determine the probability, divide by 2n.
Chaitin's incompleteness theorem
By the above theorem (), most strings are complex in the sense that they cannot be described in any significantly "compressed" way. However, it turns out that the fact that a specific string is complex cannot be formally proven, if the complexity of the string is above a certain threshold. The precise formalization is as follows. First, fix a particular axiomatic system S for the natural numbers. The axiomatic system has to be powerful enough so that, to certain assertions A about complexity of strings, one can associate a formula FA in S. This association must have the following property: | Kolmogorov complexity | Wikipedia | 487 | 1635 | https://en.wikipedia.org/wiki/Kolmogorov%20complexity | Mathematics | Complexity theory | null |
If FA is provable from the axioms of S, then the corresponding assertion A must be true. This "formalization" can be achieved based on a Gödel numbering.
Theorem: There exists a constant L (which only depends on S and on the choice of description language) such that there does not exist a string s for which the statement
K(s) ≥ L (as formalized in S)
can be proven within S.
Proof Idea: The proof of this result is modeled on a self-referential construction used in Berry's paradox. We firstly obtain a program which enumerates the proofs within S and we specify a procedure P which takes as an input an integer L and prints the strings x which are within proofs within S of the statement K(x) ≥ L. By then setting L to greater than the length of this procedure P, we have that the required length of a program to print x as stated in K(x) ≥ L as being at least L is then less than the amount L since the string x was printed by the procedure P. This is a contradiction. So it is not possible for the proof system S to prove K(x) ≥ L for L arbitrarily large, in particular, for L larger than the length of the procedure P, (which is finite).
Proof:
We can find an effective enumeration of all the formal proofs in S by some procedure
function NthProof(int n)
which takes as input n and outputs some proof. This function enumerates all proofs. Some of these are proofs for formulas we do not care about here, since every possible proof in the language of S is produced for some n. Some of these are complexity formulas of the form K(s) ≥ n where s and n are constants in the language of S. There is a procedure
function NthProofProvesComplexityFormula(int n)
which determines whether the nth proof actually proves a complexity formula K(s) ≥ L. The strings s, and the integer L in turn, are computable by procedure:
function StringNthProof(int n)
function ComplexityLowerBoundNthProof(int n)
Consider the following procedure: | Kolmogorov complexity | Wikipedia | 464 | 1635 | https://en.wikipedia.org/wiki/Kolmogorov%20complexity | Mathematics | Complexity theory | null |
function GenerateProvablyComplexString(int n)
for i = 1 to infinity:
if NthProofProvesComplexityFormula(i) and ComplexityLowerBoundNthProof(i) ≥ n
return StringNthProof(i)
Given an n, this procedure tries every proof until it finds a string and a proof in the formal system S of the formula K(s) ≥ L for some L ≥ n; if no such proof exists, it loops forever.
Finally, consider the program consisting of all these procedure definitions, and a main call:
GenerateProvablyComplexString(n0)
where the constant n0 will be determined later on. The overall program length can be expressed as U+log2(n0), where U is some constant and log2(n0) represents the length of the integer value n0, under the reasonable assumption that it is encoded in binary digits. We will choose n0 to be greater than the program length, that is, such that n0 > U+log2(n0). This is clearly true for n0 sufficiently large, because the left hand side grows linearly in n0 whilst the right hand side grows logarithmically in n0 up to the fixed constant U.
Then no proof of the form "K(s)≥L" with L≥n0 can be obtained in S, as can be seen by an indirect argument:
If ComplexityLowerBoundNthProof(i) could return a value ≥n0, then the loop inside GenerateProvablyComplexString would eventually terminate, and that procedure would return a string s such that
This is a contradiction, Q.E.D.
As a consequence, the above program, with the chosen value of n0, must loop forever.
Similar ideas are used to prove the properties of Chaitin's constant.
Minimum message length | Kolmogorov complexity | Wikipedia | 398 | 1635 | https://en.wikipedia.org/wiki/Kolmogorov%20complexity | Mathematics | Complexity theory | null |
The minimum message length principle of statistical and inductive inference and machine learning was developed by C.S. Wallace and D.M. Boulton in 1968. MML is Bayesian (i.e. it incorporates prior beliefs) and information-theoretic. It has the desirable properties of statistical invariance (i.e. the inference transforms with a re-parametrisation, such as from polar coordinates to Cartesian coordinates), statistical consistency (i.e. even for very hard problems, MML will converge to any underlying model) and efficiency (i.e. the MML model will converge to any true underlying model about as quickly as is possible). C.S. Wallace and D.L. Dowe (1999) showed a formal connection between MML and algorithmic information theory (or Kolmogorov complexity).
Kolmogorov randomness
Kolmogorov randomness defines a string (usually of bits) as being random if and only if every computer program that can produce that string is at least as long as the string itself. To make this precise, a universal computer (or universal Turing machine) must be specified, so that "program" means a program for this universal machine. A random string in this sense is "incompressible" in that it is impossible to "compress" the string into a program that is shorter than the string itself. For every universal computer, there is at least one algorithmically random string of each length. Whether a particular string is random, however, depends on the specific universal computer that is chosen. This is because a universal computer can have a particular string hard-coded in itself, and a program running on this universal computer can then simply refer to this hard-coded string using a short sequence of bits (i.e. much shorter than the string itself). | Kolmogorov complexity | Wikipedia | 380 | 1635 | https://en.wikipedia.org/wiki/Kolmogorov%20complexity | Mathematics | Complexity theory | null |
This definition can be extended to define a notion of randomness for infinite sequences from a finite alphabet. These algorithmically random sequences can be defined in three equivalent ways. One way uses an effective analogue of measure theory; another uses effective martingales. The third way defines an infinite sequence to be random if the prefix-free Kolmogorov complexity of its initial segments grows quickly enough — there must be a constant c such that the complexity of an initial segment of length n is always at least n−c. This definition, unlike the definition of randomness for a finite string, is not affected by which universal machine is used to define prefix-free Kolmogorov complexity.
Relation to entropy
For dynamical systems, entropy rate and algorithmic complexity of the trajectories are related by a theorem of Brudno, that the equality holds for almost all .
It can be shown that for the output of Markov information sources, Kolmogorov complexity is related to the entropy of the information source. More precisely, the Kolmogorov complexity of the output of a Markov information source, normalized by the length of the output, converges almost surely (as the length of the output goes to infinity) to the entropy of the source.
Theorem. (Theorem 14.2.5 ) The conditional Kolmogorov complexity of a binary string satisfieswhere is the binary entropy function (not to be confused with the entropy rate).
Halting problem
The Kolmogorov complexity function is equivalent to deciding the halting problem.
If we have a halting oracle, then the Kolmogorov complexity of a string can be computed by simply trying every halting program, in lexicographic order, until one of them outputs the string.
The other direction is much more involved. It shows that given a Kolmogorov complexity function, we can construct a function , such that for all large , where is the Busy Beaver shift function (also denoted as ). By modifying the function at lower values of we get an upper bound on , which solves the halting problem.
Consider this program , which takes input as , and uses .
List all strings of length .
For each such string , enumerate all (prefix-free) programs of length until one of them does output . Record its runtime .
Output the largest .
We prove by contradiction that for all large .
Let be a Busy Beaver of length . Consider this (prefix-free) program, which takes no input: | Kolmogorov complexity | Wikipedia | 509 | 1635 | https://en.wikipedia.org/wiki/Kolmogorov%20complexity | Mathematics | Complexity theory | null |
Run the program , and record its runtime length .
Generate all programs with length . Run every one of them for up to steps. Note the outputs of those that have halted.
Output the string with the lowest lexicographic order that has not been output by any of those.
Let the string output by the program be .
The program has length , where comes from the length of the Busy Beaver , comes from using the (prefix-free) Elias delta code for the number , and comes from the rest of the program. Therefore,for all big . Further, since there are only so many possible programs with length , we have by pigeonhole principle.
By assumption, , so every string of length has a minimal program with runtime . Thus, the string has a minimal program with runtime . Further, that program has length . This contradicts how was constructed.
Universal probability
Fix a universal Turing machine , the same one used to define the (prefix-free) Kolmogorov complexity. Define the (prefix-free) universal probability of a string to beIn other words, it is the probability that, given a uniformly random binary stream as input, the universal Turing machine would halt after reading a certain prefix of the stream, and output .
Note. does not mean that the input stream is , but that the universal Turing machine would halt at some point after reading the initial segment , without reading any further input, and that, when it halts, its has written to the output tape.
Theorem. (Theorem 14.11.1)
Conditional versions
The conditional Kolmogorov complexity of two strings is, roughly speaking, defined as the Kolmogorov complexity of x given y as an auxiliary input to the procedure.
There is also a length-conditional complexity , which is the complexity of x given the length of x as known/input.
Time-bounded complexity
Time-bounded Kolmogorov complexity is a modified version of Kolmogorov complexity where the space of programs to be searched for a solution is confined to only programs that can run within some pre-defined number of steps. It is hypothesised that the possibility of the existence of an efficient algorithm for determining approximate time-bounded Kolmogorov complexity is related to the question of whether true one-way functions exist. | Kolmogorov complexity | Wikipedia | 463 | 1635 | https://en.wikipedia.org/wiki/Kolmogorov%20complexity | Mathematics | Complexity theory | null |
Aloe (; also written Aloë) is a genus containing over 650 species of flowering succulent plants. The most widely known species is Aloe vera, or "true aloe". It is called this because it is cultivated as the standard source for assorted pharmaceutical purposes. Other species, such as Aloe ferox, are also cultivated or harvested from the wild for similar applications.
The APG IV system (2016) places the genus in the family Asphodelaceae, subfamily Asphodeloideae. Within the subfamily it may be placed in the tribe Aloeae. In the past, it has been assigned to the family Aloaceae (now included in the Asphodeloidae) or to a broadly circumscribed family Liliaceae (the lily family). The plant Agave americana, which is sometimes called "American aloe", belongs to the Asparagaceae, a different family.
The genus is native to tropical and southern Africa, Madagascar, Jordan, the Arabian Peninsula, and various islands in the Indian Ocean (Mauritius, Réunion, Comoros, etc.). A few species have also become naturalized in other regions (Mediterranean, India, Australia, North and South America, Hawaiian Islands, etc.).
Etymology
The genus name Aloe is derived from the Arabic word alloeh, meaning "bitter and shiny substance" or from Hebrew ahalim, plural of ahal.
Description
Most Aloe species have a rosette of large, thick, fleshy leaves. Aloe flowers are tubular, frequently yellow, orange, pink, or red, and are borne, densely clustered and pendant, at the apex of simple or branched, leafless stems. Many species of Aloe appear to be stemless, with the rosette growing directly at ground level; other varieties may have a branched or unbranched stem from which the fleshy leaves spring. They vary in color from grey to bright-green and are sometimes striped or mottled. Some aloes native to South Africa are tree-like (arborescent).
Systematics
The APG IV system (2016) places the genus in the family Asphodelaceae, subfamily Asphodeloideae. In the past it has also been assigned to the families Liliaceae and Aloeaceae, as well as the family Asphodelaceae sensu stricto, before this was merged into the Asphodelaceae sensu lato. | Aloe | Wikipedia | 506 | 1650 | https://en.wikipedia.org/wiki/Aloe | Biology and health sciences | Monocots | null |
The circumscription of the genus has varied widely. Many genera, such as Lomatophyllum, have been brought into synonymy. Species at one time placed in Aloe, such as Agave americana, have been moved to other genera. Molecular phylogenetic studies, particularly from 2010 onwards, suggested that as then circumscribed, Aloe was not monophyletic and should be divided into more tightly defined genera. In 2014, John Charles Manning and coworkers produced a phylogeny in which Aloe was divided into six genera: Aloidendron, Kumara, Aloiampelos, Aloe, Aristaloe and Gonialoe.
Species
Over 600 species are accepted in the genus Aloe, plus even more synonyms and unresolved species, subspecies, varieties, and hybrids. Some of the accepted species are: | Aloe | Wikipedia | 178 | 1650 | https://en.wikipedia.org/wiki/Aloe | Biology and health sciences | Monocots | null |
Aloe aculeata Pole-Evans
Aloe africana Mill.
Aloe albida (Stapf) Reynolds
Aloe albiflora Guillaumin
Aloe arborescens Mill.
Aloe arenicola Reynolds
Aloe argenticauda Merxm. & Giess
Aloe bakeri Scott-Elliot
Aloe ballii Reynolds
Aloe ballyi Reynolds
Aloe brevifolia Mill.
Aloe broomii Schönland
Aloe buettneri A.Berger
Aloe camperi Schweinf.
Aloe capitata Baker
Aloe comosa Marloth & A.Berger
Aloe cooperi Baker
Aloe corallina Verd.
Aloe dewinteri Giess ex Borman & Hardy
Aloe erinacea D.S.Hardy
Aloe excelsa A.Berger
Aloe ferox Mill.
Aloe forbesii Balf.f.
Aloe helenae Danguy
Aloe hereroensis Engl.
Aloe inermis Forssk.
Aloe inyangensis Christian
Aloe jawiyon S.J.Christie, D.P.Hannon & Oakman ex A.G.Mill.
Aloe jucunda Reynolds
Aloe khamiesensis Pillans
Aloe kilifiensis Christian
Aloe maculata All.
Aloe marlothii A.Berger
Aloe mubendiensis Christian
Aloe namibensis Giess
Aloe nyeriensis Christian & I.Verd.
Aloe pearsonii Schönland
Aloe peglerae Schönland
Aloe perfoliata L.
Aloe perryi Baker
Aloe petricola Pole-Evans
Aloe polyphylla Pillans
Aloe rauhii Reynolds
Aloe reynoldsii Letty
Aloe scobinifolia Reynolds & Bally
Aloe sinkatana Reynolds
Aloe squarrosa Baker ex Balf.f.
Aloe striata Haw.
Aloe succotrina Lam.
Aloe suzannae Decary
Aloe thraskii Baker
Aloe vera (L.) Burm.f.
Aloe viridiflora Reynolds
Aloe wildii (Reynolds) Reynolds
In addition to the species and hybrids between species within the genus, several hybrids with other genera have been created in cultivation, such as between Aloe and Gasteria (× Gasteraloe), and between Aloe and Astroloba (×Aloloba). | Aloe | Wikipedia | 498 | 1650 | https://en.wikipedia.org/wiki/Aloe | Biology and health sciences | Monocots | null |
Uses
Aloe species are frequently cultivated as ornamental plants both in gardens and in pots. Many aloe species are highly decorative and are valued by collectors of succulents. Aloe vera is used both internally and externally on humans as folk or alternative medicine. The Aloe species is known for its medicinal and cosmetic properties. Around 75% of Aloe species are used locally for medicinal uses. The plants can also be made into types of special soaps or used in other skin care products (see natural skin care).
Numerous cultivars with mixed or uncertain parentage are grown. Of these, Aloe 'Lizard Lips' has gained the Royal Horticultural Society's Award of Garden Merit.
Aloe variegata has been planted on graves in the belief that this ensures eternal life.
Historical uses
Historical use of various aloe species is well documented. Documentation of the clinical effectiveness is available, although relatively limited.
Of the 500+ species, only a few were used traditionally as herbal medicines, Aloe vera again being the most commonly used species. Also included are A. perryi and A. ferox. The Ancient Greeks and Romans used Aloe vera to treat wounds. In the Middle Ages, the yellowish liquid found inside the leaves was favored as a purgative. Unprocessed aloe that contains aloin is generally used as a laxative, whereas processed juice does not usually contain significant aloin.
According to Cancer Research UK, a potentially deadly product called T-UP is made of concentrated aloe, and promoted as a cancer cure. They say "there is currently no evidence that aloe products can help to prevent or treat cancer in humans".
Aloin in OTC laxative products
On May 9, 2002, the US Food and Drug Administration issued a final rule banning the use of aloin, the yellow sap of the aloe plant, for use as a laxative ingredient in over-the-counter drug products. Most aloe juices today do not contain significant aloin. | Aloe | Wikipedia | 407 | 1650 | https://en.wikipedia.org/wiki/Aloe | Biology and health sciences | Monocots | null |
Chemical properties
According to W. A. Shenstone, two classes of aloins are recognized: (1) nataloins, which yield picric and oxalic acids with nitric acid, and do not give a red coloration with nitric acid; and (2) barbaloins, which yield aloetic acid (C7H2N3O5), chrysammic acid (C7H2N2O6), picric and oxalic acids with nitric acid, being reddened by the acid. This second group may be divided into a-barbaloins, obtained from Barbados Aloe, and reddened in the cold, and b-barbaloins, obtained from Aloe Socotrina and Zanzibar Aloe, reddened by ordinary nitric acid only when warmed or by fuming acid in the cold. Nataloin (2C17H13O7·H2O) forms bright-yellow scales, barbaloin (C17H18O7) prismatic crystals. Aloe species are used in essential oils as a safety measure to dilute the solution before they are applied to the skin.
Flavoring
Aloe perryi, A. barbadensis, A. ferox, and hybrids of this species with A. africana and A. spicata are listed as natural flavoring substances in the US government Electronic Code of Federal Regulations. Aloe socotrina is said to be used in yellow Chartreuse.
Gallery | Aloe | Wikipedia | 310 | 1650 | https://en.wikipedia.org/wiki/Aloe | Biology and health sciences | Monocots | null |
Amaryllis () is the only genus in the subtribe Amaryllidinae (tribe Amaryllideae). It is a small genus of flowering bulbs, with two species. The better known of the two, Amaryllis belladonna, is a native of the Western Cape region of South Africa, particularly the rocky southwest area between the Olifants River Valley and Knysna.
For many years there was confusion among botanists over the generic names Amaryllis and Hippeastrum, one result of which is that the common name 'amaryllis' is mainly used for cultivars of the genus Hippeastrum, widely sold in the winter months for their ability to bloom indoors.
Plants of the genus Amaryllis are known as belladonna lily, Jersey lily, naked lady, amarillo, Easter lily in Southern Australia or, in South Africa, March lily due to its propensity to flower around March. This is one of numerous genera with the common name 'lily' due to their flower shape and growth habit. However, they are only distantly related to the true lily, Lilium. In the Victorian language of flowers, amaryllis means "love, beauty, and determination", and can also represent hope and achievement.
Description
Amaryllis is a bulbous plant, with each bulb being in diameter. It has several strap-shaped, hysteranthous, green leaves with midrib, long and broad, arranged in two rows.
Each bulb produces one or two leafless, stout, persistent and erect stems tall, each of which bears at the top a cluster of two to twelve zygomorphic, funnel-shaped flowers without a tube. Each flower is in diameter with six spreading tepals (three outer sepals, three inner petals, with similar appearance to each other). The usual color is white with crimson veins, but pink or purple also occur naturally. Stamens are very shortly connate basally, declinate, unequal. Style is declinate, stigma is three-lobed. Ovules are approx. 8 per locule. Seeds are compressed-globose, white to pink. The number of chromosomes is 2n = 22. | Amaryllis | Wikipedia | 460 | 1680 | https://en.wikipedia.org/wiki/Amaryllis | Biology and health sciences | Monocots | null |
Taxonomy
The single genus is in subtribe Amaryllidinae, in the tribe Amaryllideae. The taxonomy of the genus has been controversial. In 1753 Carl Linnaeus created the name Amaryllis belladonna, the type species of the genus Amaryllis. At the time both South African and South American plants were placed in the same genus; subsequently they were separated into two different genera. The key question is whether Linnaeus's type was a South African plant or a South American plant. If the latter, Amaryllis would be the correct name for the genus Hippeastrum, and a different name would have to be used for the genus discussed here. Alan W. Meerow et al. have briefly summarized the debate, which took place from 1938 onwards and involved botanists on both sides of the Atlantic. The outcome was a decision by the 14th International Botanical Congress in 1987 that Amaryllis should be a conserved name (i.e. correct regardless of priority) and ultimately based on a specimen of the South African Amaryllis belladonna from the Clifford Herbarium at the Natural History Museum in London.
Species
, Amaryllis had only two accepted species, both native to the Cape Provinces of South Africa:
Amaryllis belladonna – south-west Cape Provinces; introduced into many parts of the world, including California, Great Britain, Australia and New Zealand
Amaryllis paradisicola – west Cape Provinces
Phylogeny
Amaryllidinae are placed within Amaryllideae as follow:
These are phylogenetically related as follows:
Etymology
The name Amaryllis is taken from a shepherdess in Virgil's pastoral Eclogues, (from the Greek .
Although the 1987 decision settled the question of the scientific name of the genus, the common name 'amaryllis' continues to be used differently. Bulbs sold as amaryllis and described as "ready to bloom for the holidays" belong to the allied genus Hippeastrum. The common name "naked lady" comes from the plant's pattern of flowering when the foliage has died down. This name is also used for other bulbs with a similar growth and flowering pattern; some of these have their own widely used and accepted common names, such as the resurrection lily (Lycoris squamigera). | Amaryllis | Wikipedia | 469 | 1680 | https://en.wikipedia.org/wiki/Amaryllis | Biology and health sciences | Monocots | null |
Habitat
In areas of its native habitat with mountainous fynbos, flowering tends to be suppressed until after bush fires as dense overhead vegetation prevents growth. In more open sandy areas of the Western Cape, the plant flowers annually. Plants tend to be very localized in dense concentrations due to the seeds' large size and heavy weight. Strong winds shake loose the seeds, which fall to ground and immediately start to germinate, aided by the first winter rains.
Ecology
The leaves are produced in the autumn or early spring in warm climates depending on the onset of rain and eventually die down by late spring. The bulb is then dormant until late summer. The plant is not frost-tolerant, nor does it do well in tropical environments since they require a dry resting period between leaf growth and flower spike production.
One or two leafless stems arise from the bulb in the dry ground in late summer (March in its native habitat and August in USDA zone 7).
The plant has a symbiotic relationship with carpenter bees. It is also visited by noctuid moths at night. The relative importance of these insects as pollinators has not yet been established; however, carpenter bees are thought to be the main pollinators of amaryllis on the Cape Peninsula. The plant's main parasite is the lily borer Brithys crini and/or Diaphone eumela.
Cultivation
Amaryllis belladonna was introduced into cultivation at the beginning of the eighteenth century. It reproduces slowly by either bulb division or seeds and has gradually naturalized from plantings in urban and suburban areas throughout the lower elevations and coastal areas in much of the West Coast of the US since these environments mimic their native South African habitat. Hardiness zones 6–8. It is also naturalized in Australia. | Amaryllis | Wikipedia | 359 | 1680 | https://en.wikipedia.org/wiki/Amaryllis | Biology and health sciences | Monocots | null |
There is an Amaryllis belladonna hybrid which was bred in the 1800s in Australia. No one knows the exact species it was crossed with to produce color variations of white, cream, peach, magenta and nearly red hues. The hybrids were crossed back onto the original Amaryllis belladonna and with each other to produce naturally seed-bearing crosses that come in a very wide range of flower sizes, shapes, stem heights and intensities of pink. Pure white varieties with bright green stems were bred as well. The hybrids are quite distinct in that the many shades of pink also have stripes, veining, darkened edges, white centers and light yellow centers, also setting them apart from the original light pink. In addition, the hybrids often produce flowers in a fuller circle rather than the "side-facing" habit of the "old-fashioned" pink. The hybrids are able to adapt to year-round watering and fertilization but can also tolerate completely dry summer conditions if need be.
A. belladonna has gained the Royal Horticultural Society's Award of Garden Merit.
Amaryllis belladonna has been crossed in cultivation with Crinum moorei to produce a hybrid called × Amarcrinum, which has named cultivars. Hybrids said to be between Amaryllis belladonna and Brunsvigia josephinae have been called × Amarygia. Neither hybrid genus name is accepted by the World Checklist of Selected Plant Families. | Amaryllis | Wikipedia | 299 | 1680 | https://en.wikipedia.org/wiki/Amaryllis | Biology and health sciences | Monocots | null |
Arthritis is a general medical term used to describe a disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, swelling, and decreased range of motion of the affected joints. In certain types of arthritis, other organs such as the skin are also affected. Onset can be gradual or sudden.
There are several types of arthritis. The most common forms are osteoarthritis (most commonly seen in weightbearing joints) and rheumatoid arthritis. Osteoarthritis usually occurs as an individual ages and often affects the hips, knees, shoulders, and fingers. Rheumatoid arthritis is an autoimmune disorder that often affects the hands and feet. Other types of arthritis include gout, lupus, and septic arthritis. These are inflammatory based types of rheumatic disease.
Early treatment for arthritis commonly includes resting the affected joint and conservative measures such as heating or icing. Weight loss and exercise may also be useful to reduce the force across a weightbearing joint. Medication intervention for symptoms depends on the form of arthritis. These may include anti-inflammatory medications such as ibuprofen and paracetamol (acetaminophen). With severe cases of arthritis, joint replacement surgery may be necessary.
Osteoarthritis is the most common form of arthritis affecting more than 3.8% of people, while rheumatoid arthritis is the second most common affecting about 0.24% of people. In Australia about 15% of people are affected by arthritis, while in the United States more than 20% have a type of arthritis. Overall arthritis becomes more common with age. Arthritis is a common reason people are unable to carryout their work and can result in decreased ability to complete activities of daily living. The term arthritis is derived from arthr- (meaning 'joint') and -itis (meaning 'inflammation').
Classification
There are several diseases where joint pain is the most prominent symptom. Generally when a person has "arthritis" it means that they have one of the following diseases:
Hemarthrosis
Osteoarthritis
Rheumatoid arthritis
Gout and pseudo-gout
Septic arthritis
Ankylosing spondylitis
Juvenile idiopathic arthritis
Still's disease
Psoriatic arthritis | Arthritis | Wikipedia | 478 | 1776 | https://en.wikipedia.org/wiki/Arthritis | Biology and health sciences | Non-infectious disease | null |
Joint pain can also be a symptom of other diseases. In this case, the person may not have arthritis and instead have one of the following diseases:
Psoriasis
Reactive arthritis
Ehlers–Danlos syndrome
Iron overload
Hepatitis
Lyme disease
Sjögren's disease
Hashimoto's thyroiditis
Celiac disease
Non-celiac gluten sensitivity
Inflammatory bowel disease (including Crohn's disease and ulcerative colitis)
Henoch–Schönlein purpura
Hyperimmunoglobulinemia D with recurrent fever
Sarcoidosis
Whipple's disease
TNF receptor associated periodic syndrome
Granulomatosis with polyangiitis (and many other vasculitis syndromes)
Familial Mediterranean fever
Systemic lupus erythematosus
An undifferentiated arthritis is an arthritis that does not fit into well-known clinical disease categories, possibly being an early stage of a definite rheumatic disease.
Signs and symptoms
Pain in varying severity is a common symptom in most types of arthritis. Other symptoms include swelling, joint stiffness, redness, and aching around the joint(s). Arthritic disorders like lupus and rheumatoid arthritis can affect other organs in the body, leading to a variety of symptoms including:
Inability to use the hand or walk
Stiffness in one or more joints
Rash or itch
Malaise and fatigue
Weight loss
Poor sleep
Muscle aches and pains
Tenderness
Difficulty moving the joint
Causes
Some common risk factors that can increase the chances of developing osteoarthritis include obesity, prior injury to the joint, type of joint, and muscle strength. The risk factors with the strongest association for developing inflammatory arthritis such as rheumatoid arthritis are the female sex, a family history of rheumatoid arthritis, age, obesity, previous joint damage from an injury, and exposure to tobacco smoke.
Risk factors
There are common risk factors that increase a person's chance of developing arthritis later in adulthood. Some of these are modifiable while others are not. Smoking has been linked to an increased susceptibility of developing arthritis, particularly rheumatoid arthritis.
Diagnosis | Arthritis | Wikipedia | 449 | 1776 | https://en.wikipedia.org/wiki/Arthritis | Biology and health sciences | Non-infectious disease | null |
Diagnosis is made by clinical examination from an appropriate health professional, and may be supported by tests such as radiologic imaging and blood tests, depending on the type of suspected arthritis. Pain patterns may vary depending on the arthritis type and the location. Rheumatoid arthritis is generally worse in the morning and associated with stiffness lasting over 30 minutes.
Important features of diagnosis are rate of onset, pattern of joint involvement, symmetry of symptoms, early morning stiffness, tenderness, locking of joint with inactivity, aggravating and relieving factors, and other systemic symptoms. Physical examination may include checking joints, evaluating gait, examination of skin for dermatological findings and symptoms of pulmonary inflammation. Physical examination may confirm the diagnosis or may indicate systemic disease. Chest radiographs are often used to follow progression or help assess severity.
Screening blood tests for suspected arthritis include: rheumatoid factor, antinuclear factor (ANF), extractable nuclear antigen, and specific antibodies.
Rheumatoid arthritis patients often have elevated erythrocyte sedimentation rate (ESR, also known as sed rate) or C-reactive protein (CRP) levels, which indicates the presence of an inflammatory process in the body. Anti-cyclic citrullinated peptide (anti-CCP) antibodies and rheumatoid factor (RF) are two more common blood tests when assessing for rheumatoid arthritis.
Imaging tests like X-rays are commonly utilized to diagnose and monitor arthritis. Other imaging tests for rheumatoid arthritis that may be considered include computed tomography (CT) scanning, positron emission tomography (PET) scanning, bone scanning, and dual-energy X-ray absorptiometry (DEXA).
Osteoarthritis | Arthritis | Wikipedia | 373 | 1776 | https://en.wikipedia.org/wiki/Arthritis | Biology and health sciences | Non-infectious disease | null |
Osteoarthritis (OA) is the most common form of arthritis. It affects humans and other animals, notably dogs, but also occurs in cats and horses. It can affect both the larger (ie. knee, hip, shoulder, etc.) and the smaller joints (ie. fingers, toes, foot, etc.) of the body. The disease is caused by daily wear and tear of the joint. This process can progress more rapidly as a result of injury to the joint. Osteoarthritis is caused by the break down of the smooth surface between two bones, known as cartilage, which can eventually lead to the two opposing bones coming in direct contact and eroding one another. OA symptoms typically begin with minor pain during physical activity, but can eventually progress to be present at rest. The pain can be debilitating and prevent one from doing activities that they would normally do as part of their daily routine. OA typically affects the weight-bearing joints, such as the back, knee and hip due to the mechanical nature of this disease process. Unlike rheumatoid arthritis, osteoarthritis is most commonly a disease of the elderly. The strongest predictor of osteoarthritis is increased age, likely due to the declining ability of chondrocytes to maintain the structural integrity of cartilage. More than 30 percent of women have some degree of osteoarthritis by age 65. One of the primary tools for diagnosing OA are X-rays of the joint. Findings on X-ray that are consistent with OA include those with joint space narrowing (due to cartilage breakdown), bone spurs, sclerosis, and bone cysts.
Rheumatoid arthritis | Arthritis | Wikipedia | 365 | 1776 | https://en.wikipedia.org/wiki/Arthritis | Biology and health sciences | Non-infectious disease | null |
Rheumatoid arthritis (RA) is a disorder in which the body's own immune system starts to attack body tissues specifically the cartilage at the end of bones known as articular cartilage. The attack is not only directed at the joint but to many other parts of the body. RA often affects joints in the fingers, wrists, knees and elbows, is symmetrical (appears on both sides of the body), and can lead to severe progressive deformity in a matter of years if not adequately treated. RA usually onsets earlier in life than OA and commonly effects people aged 20 and above. In children, the disorder can present with a skin rash, fever, pain, disability, and limitations in daily activities. With earlier diagnosis and appropriate aggressive treatment, many individuals can obtain control of their symptoms leading to a better quality of life compared to those without treatment.
One of the main triggers of bone erosion in the joints in rheumatoid arthritis is inflammation of the synovium (lining of the joint capsule), caused in part by the production of pro-inflammatory cytokines and receptor activator of nuclear factor kappa B ligand (RANKL), a cell surface protein present in Th17 cells and osteoblasts. Osteoclast activity can be directly induced by osteoblasts through the RANK/RANKL mechanism.
Lupus
Lupus is an autoimmune collagen vascular disorder that can be present with severe arthritis. Other features of lupus include a skin rash, extreme photosensitivity, hair loss, kidney problems, lung fibrosis and constant joint pain.
Gout | Arthritis | Wikipedia | 337 | 1776 | https://en.wikipedia.org/wiki/Arthritis | Biology and health sciences | Non-infectious disease | null |
Gout is caused by deposition of uric acid crystals in the joints, causing inflammation. There is also an uncommon form of gouty arthritis caused by the formation of rhomboid crystals of calcium pyrophosphate known as pseudogout. In the early stages, the gouty arthritis usually occurs in one joint, but with time, it can occur in many joints and be quite crippling. The joints in gout can often become swollen and lose function. Gouty arthritis can become particularly painful and potentially debilitating when gout cannot successfully be treated. When uric acid levels and gout symptoms cannot be controlled with standard gout medicines that decrease the production of uric acid (e.g., allopurinol) or increase uric acid elimination from the body through the kidneys (e.g., probenecid), this can be referred to as refractory chronic gout.
Comparison of types
Other
Infectious arthritis is another severe form of arthritis that is sometimes referred to as septic arthritis. It presents with infections symptoms that can include sudden onset of chills, fever, and joint pain. The condition is caused by bacteria, that can spread through the blood stream from elsewhere in the body, that infects a joint and begins to erode cartilage. Infectious arthritis must be rapidly diagnosed and treated promptly to prevent irreversible joint damage. Only about 1% of cases of infectious arthritis are due to any of a wide variety of viruses. The virus SARS-CoV-2, which causes Covid-19 has been added to the list of viruses which can cause infections arthritis. SARS-CoV-2 causes reactive arthritis rather than local septic arthritis.
Psoriasis can develop into psoriatic arthritis. With psoriatic arthritis, most individuals develop the skin symptoms first and then the joint related symptoms. The typical features are continuous joint pains, stiffness and swelling like other forms of arthritis. The disease does recur with periods of remission but there is no known cure for the disorder. Treatment current revolves around decreasing autoimmune attacks with immune suppression medications. A small percentage develop a severely painful and destructive form of arthritis which destroys the small joints in the hands and can lead to permanent disability and loss of hand function. | Arthritis | Wikipedia | 472 | 1776 | https://en.wikipedia.org/wiki/Arthritis | Biology and health sciences | Non-infectious disease | null |
Treatment
There is no known cure for arthritis and rheumatic diseases. Treatment options vary depending on the type of arthritis and include physical therapy, exercise and diet, orthopedic bracing, and oral and topical medications. Joint replacement surgery may be required to repair damage, restore function, or relieve pain.
Physical therapy
In general, studies have shown that physical exercise of the affected joint can noticeably improve long-term pain relief. Furthermore, exercise of the arthritic joint is encouraged to maintain the health of the particular joint and the overall body of the person.
Individuals with arthritis can benefit from both physical and occupational therapy. In arthritis the joints become stiff and the range of movement can be limited. Physical therapy has been shown to significantly improve function, decrease pain, and delay the need for surgical intervention in advanced cases. Exercise prescribed by a physical therapist has been shown to be more effective than medications in treating osteoarthritis of the knee. Exercise often focuses on improving muscle strength, endurance and flexibility. In some cases, exercises may be designed to train balance. Occupational therapy can provide assistance with activities. Assistive technology is a tool used to aid a person's disability by reducing their physical barriers by improving the use of their damaged body part, typically after an amputation. Assistive technology devices can be customized to the patient or bought commercially.
Medications
There are several types of medications that are used for the treatment of arthritis. Treatment typically begins with medications that have the fewest side effects with further medications being added if insufficiently effective.
Depending on the type of arthritis, the medications that are given may be different. For example, the first-line treatment for osteoarthritis is acetaminophen (paracetamol) while for inflammatory arthritis it involves non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen. Opioids and NSAIDs may be less well tolerated. However, topical NSAIDs may have better safety profiles than oral NSAIDs. For more severe cases of osteoarthritis, intra-articular corticosteroid injections may also be considered. | Arthritis | Wikipedia | 432 | 1776 | https://en.wikipedia.org/wiki/Arthritis | Biology and health sciences | Non-infectious disease | null |
The drugs to treat rheumatoid arthritis (RA) range from corticosteroids to monoclonal antibodies given intravenously. Due to the autoimmune nature of RA, treatments may include not only pain medications and anti-inflammatory drugs, but also another category of drugs called disease-modifying antirheumatic drugs (DMARDs). csDMARDs, TNF biologics and tsDMARDs are specific kinds of DMARDs that are recommended for treatment. Treatment with DMARDs is designed to slow down the progression of RA by initiating an adaptive immune response, in part by CD4+ T helper (Th) cells, specifically Th17 cells. Th17 cells are present in higher quantities at the site of bone destruction in joints and produce inflammatory cytokines associated with inflammation, such as interleukin-17 (IL-17).
Surgery
A number of surgical interventions have been incorporated in the treatment of arthritis since the 1950s. The primary surgical treatment option of arthritis is joint replacement surgery known as arthroplasty. Common joints that are replaced due to arthritis include the shoulder, hip, and knee. Arthroscopic surgery for osteoarthritis of the knee provides no additional benefit to patients when compared to optimized physical and medical therapy. Joint replacement surgery can last anywhere from 15-30 years depending on the patient. Following joint replacement surgery, patients can expect to get back to several physical activities including those such as swimming, tennis, and golf.
Adaptive aids
People with hand arthritis can have trouble with simple activities of daily living tasks (ADLs), such as turning a key in a lock or opening jars, as these activities can be cumbersome and painful. There are adaptive aids or assistive devices (ADs) available to help with these tasks, but they are generally more costly than conventional products with the same function. It is now possible to 3-D print adaptive aids, which have been released as open source hardware to reduce patient costs. Adaptive aids can significantly help arthritis patients and the vast majority of those with arthritis need and use them.
Alternative medicine
Further research is required to determine if transcutaneous electrical nerve stimulation (TENS) for knee osteoarthritis is effective for controlling pain.
Low level laser therapy may be considered for relief of pain and stiffness associated with arthritis. Evidence of benefit is tentative. | Arthritis | Wikipedia | 486 | 1776 | https://en.wikipedia.org/wiki/Arthritis | Biology and health sciences | Non-infectious disease | null |
Pulsed electromagnetic field therapy (PEMFT) has tentative evidence supporting improved functioning but no evidence of improved pain in osteoarthritis. The FDA has not approved PEMFT for the treatment of arthritis. In Canada, PEMF devices are legally licensed by Health Canada for the treatment of pain associated with arthritic conditions.
Epidemiology
Arthritis is predominantly a disease of the elderly, but children can also be affected by the disease. Arthritis is more common in women than men at all ages and affects all races, ethnic groups and cultures. In the United States a CDC survey based on data from 2013 to 2015 showed 54.4 million (22.7%) adults had self-reported doctor-diagnosed arthritis, and 23.7 million (43.5% of those with arthritis) had arthritis-attributable activity limitation (AAAL). With an aging population, this number is expected to increase. Adults with co-morbid conditions, such as heart disease, diabetes, and obesity, were seen to have a higher than average prevalence of doctor-diagnosed arthritis (49.3%, 47.1%, and 30.6% respectively). | Arthritis | Wikipedia | 239 | 1776 | https://en.wikipedia.org/wiki/Arthritis | Biology and health sciences | Non-infectious disease | null |
Disability due to musculoskeletal disorders increased by 45% from 1990 to 2010. Of these, osteoarthritis is the fastest increasing major health condition. Among the many reports on the increased prevalence of musculoskeletal conditions, data from Africa are lacking and underestimated. A systematic review assessed the prevalence of arthritis in Africa and included twenty population-based and seven hospital-based studies. The majority of studies, twelve, were from South Africa. Nine studies were well-conducted, eleven studies were of moderate quality, and seven studies were conducted poorly. The results of the systematic review were as follows:
Rheumatoid arthritis: 0.1% in Algeria (urban setting); 0.6% in Democratic Republic of Congo (urban setting); 2.5% and 0.07% in urban and rural settings in South Africa respectively; 0.3% in Egypt (rural setting), 0.4% in Lesotho (rural setting)
Osteoarthritis: 55.1% in South Africa (urban setting); ranged from 29.5 to 82.7% in South Africans aged 65 years and older
Knee osteoarthritis has the highest prevalence from all types of osteoarthritis, with 33.1% in rural South Africa
Ankylosing spondylitis: 0.1% in South Africa (rural setting)
Psoriatic arthritis: 4.4% in South Africa (urban setting)
Gout: 0.7% in South Africa (urban setting)
Juvenile idiopathic arthritis: 0.3% in Egypt (urban setting)
History
Evidence of osteoarthritis and potentially inflammatory arthritis has been discovered in dinosaurs. The first known traces of human arthritis date back as far as 4500 BC. In early reports, arthritis was frequently referred to as the most common ailment of prehistoric peoples. It was noted in skeletal remains of Native Americans found in Tennessee and parts of what is now Olathe, Kansas. Evidence of arthritis has been found throughout history, from Ötzi, a mummy () found along the border of modern Italy and Austria, to the Egyptian mummies . | Arthritis | Wikipedia | 448 | 1776 | https://en.wikipedia.org/wiki/Arthritis | Biology and health sciences | Non-infectious disease | null |
In 1715, William Musgrave published the second edition of his most important medical work, De arthritide symptomatica, which concerned arthritis and its effects. Augustin Jacob Landré-Beauvais, a 28-year-old resident physician at Salpêtrière Asylum in France was the first person to describe the symptoms of rheumatoid arthritis. Though Landré-Beauvais' classification of rheumatoid arthritis as a relative of gout was inaccurate, his dissertation encouraged others to further study the disease.
John Charnley completed the first hip replacement (total hip arthroplasty) in England to treat arthritis in the 1960s.
Society and Culture:
Arthritis is the most common cause of disability in the United States. More than 20 million individuals with arthritis have severe limitations in function on a daily basis. Absenteeism and frequent visits to the physician are common in individuals who have arthritis. Arthritis can make it difficult for individuals to be physically active and some become home bound.
It is estimated that the total cost of arthritis cases is close to $100 billion of which almost 50% is from lost earnings.
Terminology
The term is derived from arthr- (from ) and -itis (from , , ), the latter suffix having come to be associated with inflammation.
The word arthritides is the plural form of arthritis, and denotes the collective group of arthritis-like conditions. | Arthritis | Wikipedia | 290 | 1776 | https://en.wikipedia.org/wiki/Arthritis | Biology and health sciences | Non-infectious disease | null |
Acetylene (systematic name: ethyne) is the chemical compound with the formula and structure . It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in its pure form and thus is usually handled as a solution. Pure acetylene is odorless, but commercial grades usually have a marked odor due to impurities such as divinyl sulfide and phosphine.
As an alkyne, acetylene is unsaturated because its two carbon atoms are bonded together in a triple bond. The carbon–carbon triple bond places all four atoms in the same straight line, with CCH bond angles of 180°.
Discovery
Acetylene was discovered in 1836 by Edmund Davy, who identified it as a "new carburet of hydrogen". It was an accidental discovery while attempting to isolate potassium metal. By heating potassium carbonate with carbon at very high temperatures, he produced a residue of what is now known as potassium carbide, (K2C2), which reacted with water to release the new gas. It was rediscovered in 1860 by French chemist Marcellin Berthelot, who coined the name acétylène. Berthelot's empirical formula for acetylene (C4H2), as well as the alternative name "quadricarbure d'hydrogène" (hydrogen quadricarbide), were incorrect because many chemists at that time used the wrong atomic mass for carbon (6 instead of 12). Berthelot was able to prepare this gas by passing vapours of organic compounds (methanol, ethanol, etc.) through a red hot tube and collecting the effluent. He also found that acetylene was formed by sparking electricity through mixed cyanogen and hydrogen gases. Berthelot later obtained acetylene directly by passing hydrogen between the poles of a carbon arc.
Preparation
Partial combustion of hydrocarbons
Since the 1950s, acetylene has mainly been manufactured by the partial combustion of methane in the US, much of the EU, and many other countries: | Acetylene | Wikipedia | 437 | 1778 | https://en.wikipedia.org/wiki/Acetylene | Physical sciences | Aliphatic hydrocarbons | Chemistry |
It is a recovered side product in production of ethylene by cracking of hydrocarbons. Approximately 400,000 tonnes were produced by this method in 1983. Its presence in ethylene is usually undesirable because of its explosive character and its ability to poison Ziegler–Natta catalysts. It is selectively hydrogenated into ethylene, usually using Pd–Ag catalysts.
Dehydrogenation of alkanes
The heaviest alkanes in petroleum and natural gas are cracked into lighter molecules which are dehydrogenated at high temperature:
This last reaction is implemented in the process of anaerobic decomposition of methane by microwave plasma.
Carbochemical method
The first acetylene produced was by Edmund Davy in 1836, via potassium carbide.
Acetylene was historically produced by hydrolysis (reaction with water) of calcium carbide:
This reaction was discovered by Friedrich Wöhler in 1862, but a suitable commercial scale production method which allowed acetylene to be put into wider scale use was not found until 1892 by the Canadian inventor Thomas Willson while searching for a viable commercial production method for aluminum.
As late as the early 21st century, China, Japan, and Eastern Europe produced acetylene primarily by this method.
The use of this technology has since declined worldwide with the notable exception of China, with its emphasis on coal-based chemical industry, as of 2013. Otherwise oil has increasingly supplanted coal as the chief source of reduced carbon.
Calcium carbide production requires high temperatures, ~2000 °C, necessitating the use of an electric arc furnace. In the US, this process was an important part of the late-19th century revolution in chemistry enabled by the massive hydroelectric power project at Niagara Falls.
Bonding
In terms of valence bond theory, in each carbon atom the 2s orbital hybridizes with one 2p orbital thus forming an sp hybrid. The other two 2p orbitals remain unhybridized. The two ends of the two sp hybrid orbital overlap to form a strong σ valence bond between the carbons, while on each of the other two ends hydrogen atoms attach also by σ bonds. The two unchanged 2p orbitals form a pair of weaker π bonds.
Since acetylene is a linear symmetrical molecule, it possesses the D∞h point group.
Physical properties | Acetylene | Wikipedia | 476 | 1778 | https://en.wikipedia.org/wiki/Acetylene | Physical sciences | Aliphatic hydrocarbons | Chemistry |
Changes of state
At atmospheric pressure, acetylene cannot exist as a liquid and does not have a melting point. The triple point on the phase diagram corresponds to the melting point (−80.8 °C) at the minimal pressure at which liquid acetylene can exist (1.27 atm). At temperatures below the triple point, solid acetylene can change directly to the vapour (gas) by sublimation. The sublimation point at atmospheric pressure is −84.0 °C.
Other
At room temperature, the solubility of acetylene in acetone is 27.9 g per kg. For the same amount of dimethylformamide (DMF), the solubility is 51 g. At
20.26 bar, the solubility increases to 689.0 and 628.0 g for acetone and DMF, respectively. These solvents are used in pressurized gas cylinders.
Applications | Acetylene | Wikipedia | 196 | 1778 | https://en.wikipedia.org/wiki/Acetylene | Physical sciences | Aliphatic hydrocarbons | Chemistry |
Welding
Approximately 20% of acetylene is supplied by the industrial gases industry for oxyacetylene gas welding and cutting due to the high temperature of the flame. Combustion of acetylene with oxygen produces a flame of over , releasing 11.8 kJ/g. Oxygen with acetylene is the hottest burning common gas mixture. Acetylene is the third-hottest natural chemical flame after dicyanoacetylene's and cyanogen at . Oxy-acetylene welding was a popular welding process in previous decades. The development and advantages of arc-based welding processes have made oxy-fuel welding nearly extinct for many applications. Acetylene usage for welding has dropped significantly. On the other hand, oxy-acetylene welding equipment is quite versatile – not only because the torch is preferred for some sorts of iron or steel welding (as in certain artistic applications), but also because it lends itself easily to brazing, braze-welding, metal heating (for annealing or tempering, bending or forming), the loosening of corroded nuts and bolts, and other applications. Bell Canada cable-repair technicians still use portable acetylene-fuelled torch kits as a soldering tool for sealing lead sleeve splices in manholes and in some aerial locations. Oxyacetylene welding may also be used in areas where electricity is not readily accessible. Oxyacetylene cutting is used in many metal fabrication shops. For use in welding and cutting, the working pressures must be controlled by a regulator, since above , if subjected to a shockwave (caused, for example, by a flashback), acetylene decomposes explosively into hydrogen and carbon.
Chemicals
Acetylene is useful for many processes, but few are conducted on a commercial scale.
One of the major chemical applications is ethynylation of formaldehyde.
Acetylene adds to aldehydes and ketones to form α-ethynyl alcohols:
The reaction gives butynediol, with propargyl alcohol as the by-product. Copper acetylide is used as the catalyst. | Acetylene | Wikipedia | 439 | 1778 | https://en.wikipedia.org/wiki/Acetylene | Physical sciences | Aliphatic hydrocarbons | Chemistry |
In addition to ethynylation, acetylene reacts with carbon monoxide, acetylene reacts to give acrylic acid, or acrylic esters. Metal catalysts are required. These derivatives form products such as acrylic fibers, glasses, paints, resins, and polymers. Except in China, use of acetylene as a chemical feedstock has declined by 70% from 1965 to 2007 owing to cost and environmental considerations. In China, acetylene is a major precursor to vinyl chloride.
Historical uses
Prior to the widespread use of petrochemicals, coal-derived acetylene was a building block for several industrial chemicals. Thus acetylene can be hydrated to give acetaldehyde, which in turn can be oxidized to acetic acid. Processes leading to acrylates were also commercialized. Almost all of these processes became obsolete with the availability of petroleum-derived ethylene and propylene.
Niche applications
In 1881, the Russian chemist Mikhail Kucherov described the hydration of acetylene to acetaldehyde using catalysts such as mercury(II) bromide. Before the advent of the Wacker process, this reaction was conducted on an industrial scale.
The polymerization of acetylene with Ziegler–Natta catalysts produces polyacetylene films. Polyacetylene, a chain of CH centres with alternating single and double bonds, was one of the first discovered organic semiconductors. Its reaction with iodine produces a highly electrically conducting material. Although such materials are not useful, these discoveries led to the developments of organic semiconductors, as recognized by the Nobel Prize in Chemistry in 2000 to Alan J. Heeger, Alan G MacDiarmid, and Hideki Shirakawa.
In the 1920s, pure acetylene was experimentally used as an inhalation anesthetic.
Acetylene is sometimes used for carburization (that is, hardening) of steel when the object is too large to fit into a furnace.
Acetylene is used to volatilize carbon in radiocarbon dating. The carbonaceous material in an archeological sample is treated with lithium metal in a small specialized research furnace to form lithium carbide (also known as lithium acetylide). The carbide can then be reacted with water, as usual, to form acetylene gas to feed into a mass spectrometer to measure the isotopic ratio of carbon-14 to carbon-12. | Acetylene | Wikipedia | 508 | 1778 | https://en.wikipedia.org/wiki/Acetylene | Physical sciences | Aliphatic hydrocarbons | Chemistry |
Acetylene combustion produces a strong, bright light and the ubiquity of carbide lamps drove much acetylene commercialization in the early 20th century. Common applications included coastal lighthouses, street lights, and automobile and mining headlamps. In most of these applications, direct combustion is a fire hazard, and so acetylene has been replaced, first by incandescent lighting and many years later by low-power/high-lumen LEDs. Nevertheless, acetylene lamps remain in limited use in remote or otherwise inaccessible areas and in countries with a weak or unreliable central electric grid.
Natural occurrence
The energy richness of the C≡C triple bond and the rather high solubility of acetylene in water make it a suitable substrate for bacteria, provided an adequate source is available. A number of bacteria living on acetylene have been identified. The enzyme acetylene hydratase catalyzes the hydration of acetylene to give acetaldehyde:
Acetylene is a moderately common chemical in the universe, often associated with the atmospheres of gas giants. One curious discovery of acetylene is on Enceladus, a moon of Saturn. Natural acetylene is believed to form from catalytic decomposition of long-chain hydrocarbons at temperatures of and above. Since such temperatures are highly unlikely on such a small distant body, this discovery is potentially suggestive of catalytic reactions within that moon, making it a promising site to search for prebiotic chemistry.
Reactions
Vinylation reactions
In vinylation reactions, H−X compounds add across the triple bond. Alcohols and phenols add to acetylene to give vinyl ethers. Thiols give vinyl thioethers. Similarly, vinylpyrrolidone and vinylcarbazole are produced industrially by vinylation of 2-pyrrolidone and carbazole.
The hydration of acetylene is a vinylation reaction, but the resulting vinyl alcohol isomerizes to acetaldehyde. The reaction is catalyzed by mercury salts. This reaction once was the dominant technology for acetaldehyde production, but it has been displaced by the Wacker process, which affords acetaldehyde by oxidation of ethylene, a cheaper feedstock. A similar situation applies to the conversion of acetylene to the valuable vinyl chloride by hydrochlorination vs the oxychlorination of ethylene. | Acetylene | Wikipedia | 498 | 1778 | https://en.wikipedia.org/wiki/Acetylene | Physical sciences | Aliphatic hydrocarbons | Chemistry |
Vinyl acetate is used instead of acetylene for some vinylations, which are more accurately described as transvinylations. Higher esters of vinyl acetate have been used in the synthesis of vinyl formate.
Organometallic chemistry
Acetylene and its derivatives (2-butyne, diphenylacetylene, etc.) form complexes with transition metals. Its bonding to the metal is somewhat similar to that of ethylene complexes. These complexes are intermediates in many catalytic reactions such as alkyne trimerisation to benzene, tetramerization to cyclooctatetraene, and carbonylation to hydroquinone:
at basic conditions (50–, 20–).
Metal acetylides, species of the formula , are also common. Copper(I) acetylide and silver acetylide can be formed in aqueous solutions with ease due to a favorable solubility equilibrium.
Acid-base reactions
Acetylene has a pKa of 25, acetylene can be deprotonated by a superbase to form an acetylide:
HC#CH + RM -> RH + HC#CM
Various organometallic and inorganic reagents are effective.
Hydrogenation
Acetylene can be semihydrogenated to ethylene, providing a feedstock for a variety of polyethylene plastics. Halogens add to the triple bond. | Acetylene | Wikipedia | 292 | 1778 | https://en.wikipedia.org/wiki/Acetylene | Physical sciences | Aliphatic hydrocarbons | Chemistry |
Safety and handling
Acetylene is not especially toxic, but when generated from calcium carbide, or CAC2, it can contain toxic impurities such as traces of phosphine and arsine, which gives it a distinct garlic-like smell. It is also highly flammable, as are most light hydrocarbons, hence its use in welding. Its most singular hazard is associated with its intrinsic instability, especially when it is pressurized: under certain conditions acetylene can react in an exothermic addition-type reaction to form a number of products, typically benzene and/or vinylacetylene, possibly in addition to carbon and hydrogen. Consequently, acetylene, if initiated by intense heat or a shockwave, can decompose explosively if the absolute pressure of the gas exceeds about . Most regulators and pressure gauges on equipment report gauge pressure, and the safe limit for acetylene therefore is 101 kPagage, or 15 psig. It is therefore supplied and stored dissolved in acetone or dimethylformamide (DMF), contained in a gas cylinder with a porous filling, which renders it safe to transport and use, given proper handling. Acetylene cylinders should be used in the upright position to avoid withdrawing acetone during use.
Information on safe storage of acetylene in upright cylinders is provided by the OSHA, Compressed Gas Association, United States Mine Safety and Health Administration (MSHA), EIGA, and other agencies.
Copper catalyses the decomposition of acetylene, and as a result acetylene should not be transported in copper pipes.
Cylinders should be stored in an area segregated from oxidizers to avoid exacerbated reaction in case of fire/leakage. Acetylene cylinders should not be stored in confined spaces, enclosed vehicles, garages, and buildings, to avoid unintended leakage leading to explosive atmosphere. In the US, National Electric Code (NEC) requires consideration for hazardous areas including those where acetylene may be released during accidents or leaks. Consideration may include electrical classification and use of listed Group A electrical components in US. Further information on determining the areas requiring special consideration is in NFPA 497. In Europe, ATEX also requires consideration for hazardous areas where flammable gases may be released during accidents or leaks. | Acetylene | Wikipedia | 481 | 1778 | https://en.wikipedia.org/wiki/Acetylene | Physical sciences | Aliphatic hydrocarbons | Chemistry |
The ten Arabic numerals (0, 1, 2, 3, 4, 5, 6, 7, 8, and 9) are the most commonly used symbols for writing numbers. The term often also implies a positional notation number with a decimal base, in particular when contrasted with Roman numerals. However the symbols are also used to write numbers in other bases, such as octal, as well as non-numerical information such as trademarks or license plate identifiers.
They are also called Western Arabic numerals, Western digits, European digits, Ghubār numerals, or Hindu–Arabic numerals due to positional notation (but not these digits) originating in India. The Oxford English Dictionary uses lowercase Arabic numerals while using the fully capitalized term Arabic Numerals for Eastern Arabic numerals. In contemporary society, the terms digits, numbers, and numerals often implies only these symbols, although it can only be inferred from context.
Europeans first learned of Arabic numerals , though their spread was a gradual process. After Italian scholar Fibonacci of Pisa encountered the numerals in the Algerian city of Béjaïa, his 13th-century work became crucial in making them known in Europe. However, their use was largely confined to Northern Italy until the invention of the printing press in the 15th century. European trade, books, and colonialism subsequently helped popularize the adoption of Arabic numerals around the world. The numerals are used worldwide—significantly beyond the contemporary spread of the Latin alphabet—and have become common in the writing systems where other numeral systems existed previously, such as Chinese and Japanese numerals.
History
Origin
Positional decimal notation including a zero symbol was developed in India, using symbols visually distinct from those that would eventually enter into international use. As the concept spread, the sets of symbols used in different regions diverged over time.
The immediate ancestors of the digits now commonly called "Arabic numerals" were introduced to Europe in the 10th century by Arabic speakers of Spain and North Africa, with digits at the time in wide use from Libya to Morocco. In the east from Egypt to Iraq and the Arabian Peninsula, the Arabs were using the Eastern Arabic numerals or "Mashriki" numerals: ٠, ١, ٢, ٣, ٤, ٥, ٦, ٧, ٨, ٩. | Arabic numerals | Wikipedia | 490 | 1786 | https://en.wikipedia.org/wiki/Arabic%20numerals | Mathematics | Language | null |
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