text stringlengths 26 3.6k | page_title stringlengths 1 71 | source stringclasses 1 value | token_count int64 10 512 | id stringlengths 2 8 | url stringlengths 31 117 | topic stringclasses 4 values | section stringlengths 4 49 ⌀ | sublist stringclasses 9 values |
|---|---|---|---|---|---|---|---|---|
In 1949, 15,000 Americans underwent cosmetic surgery procedures and by 1969 this number rose to almost half a million people. The American Society of Plastic Surgeons estimates that more than 333,000 cosmetic procedures were performed on patients 18 years of age or younger in the US in 2005 compared to approx. 14,000 in 1996. In 2018, more than 226,994 patients between the ages of 13 and 19 underwent plastic surgery compared to just over 218,900 patients in the same age group in 2010. Concerns about young people undergoing plastic surgery include the financial burden of additional surgical procedures needed to correct problems after the initial cosmetic surgery, long-term health complications from plastic surgery, and unaddressed mental health issues that may have led to surgery. The increased use of cosmetic procedures crosses racial and ethnic lines in the U.S., with increases seen among African-Americans, Asian Americans and Hispanic Americans as well as Caucasian Americans. In Asia, cosmetic surgery has become more popular, and countries such as China and India have become Asia's biggest cosmetic surgery markets. South Korea is also rising in popularity in Asian and Western countries due to their expertise in facial bone surgeries (see cosmetic surgery in South Korea).
Plastic surgery is increasing slowly, rising 115% from 2000 to 2015. "According to the annual plastic surgery procedural statistics, there were 15.9 million surgical and minimally-invasive cosmetic procedures performed in the United States in 2015, a 2 percent increase over 2014." A study from 2021 found that requests for cosmetic procedures had increased significantly since the beginning of the COVID-19 pandemic, possibly due to the increase in videoconferencing; cited estimates include a 10% increase in the United States and a 20% increase in France. | Plastic surgery | Wikipedia | 353 | 42048 | https://en.wikipedia.org/wiki/Plastic%20surgery | Biology and health sciences | Medical procedures | null |
The most popular aesthetic/cosmetic procedures include:
Abdominoplasty ("tummy tuck"): reshaping and firming of the abdomen
Blepharoplasty ("eyelid surgery"): reshaping of upper/lower eyelids including Asian blepharoplasty
Phalloplasty ("penile surgery"): construction (or reconstruction) of a penis or, sometimes, artificial modification of the penis by surgery, often for cosmetic purposes
Mammoplasty:
Breast augmentations ("breast implant" or "boob job"): augmentation of the breasts by means of fat grafting, saline, or silicone gel prosthetics, which was initially performed for women with micromastia
Reduction mammoplasty ("breast reduction"): removal of skin and glandular tissue, which is done to reduce back and shoulder pain in women with gigantomastia and for men with gynecomastia
Mastopexy ("breast lift"): Lifting or reshaping of breasts to make them less saggy, often after weight loss (after a pregnancy, for example). It involves removal of breast skin as opposed to glandular tissue
Augmentation mastopexy ("breast lift with breast implants"): Lifting breasts to make them less saggy, repositioning the nipple to a higher location, and increasing breast size with saline or silicone gel implants. Recent studies of a newer technique for simultaneous augmentation mastopexy (SAM) indicate that it is a safe surgical procedure with minimal medical complications. The SAM technique involves invaginating and tacking the tissues first, in order to previsualize the result, before making any surgical incisions to the breast.
Buttock augmentation ("butt implant"): enhancement of the buttocks using silicone implants or fat grafting ("Brazilian butt lift") where fat is transferred from other areas of the body
Cryolipolysis: refers to a medical device used to destroy fat cells. Its principle relies on controlled cooling for non-invasive local reduction of fat deposits to reshape body contours.
Cryoneuromodulation: Treatment of superficial and subcutaneous tissue structures using gaseous nitrous oxide, including temporary wrinkle reduction, temporary pain reduction, treatment of dermatologic conditions, and focal cryo-treatment of tissue | Plastic surgery | Wikipedia | 500 | 42048 | https://en.wikipedia.org/wiki/Plastic%20surgery | Biology and health sciences | Medical procedures | null |
Calf augmentation: done by silicone implants or fat transfer to add bulk to calf muscles
Labiaplasty: surgical reduction and reshaping of the labia
Lip augmentation: alter the appearance of the lips by increasing their fullness through surgical enlargement with lip implants or nonsurgical enhancement with injectable fillers
Cheiloplasty: surgical reconstruction of the lip
Rhinoplasty ("nose job"): reshaping of the nose sometimes used to correct breathing impaired by structural defects.
Otoplasty ("ear surgery"/"ear pinning"): reshaping of the ear, most often done by pinning the protruding ear closer to the head.
Rhytidectomy ("face lift"): removal of wrinkles and signs of aging from the face
Neck lift: tightening of lax tissues in the neck. This procedure is often combined with a facelift for lower face rejuvenation.
Browplasty ("brow lift" or "forehead lift"): elevates eyebrows, smooths forehead skin
Midface lift ("cheek lift"): tightening of the cheeks
Genioplasty: augmentation of the chin with an individual's bones or with the use of an implant, usually silicone, by suture of the soft tissue
Mentoplasty: surgery to the chin. This can involve either enhancing or reducing the size of the chin. Enhancements are achieved with the use of facial implants. Reduction of the chin involved reducing the size of the chin bone.
Cheek augmentation ("cheek implant"): implants to the cheek
Orthognathic surgery: altering the upper and lower jaw bones (through osteotomy) to correct jaw alignment issues and correct the teeth alignment
Fillers injections: collagen, fat, and other tissue filler injections, such as hyaluronic acid
Brachioplasty ("Arm lift"): reducing excess skin and fat between the underarm and the elbow
Laser skin rejuvenation or laser resurfacing: the lessening of depth of facial pores and exfoliation of dead or damaged skin cells
Liposuction ("suction lipectomy"): removal of fat deposits by traditional suction technique or ultrasonic energy to aid fat removal | Plastic surgery | Wikipedia | 482 | 42048 | https://en.wikipedia.org/wiki/Plastic%20surgery | Biology and health sciences | Medical procedures | null |
Zygoma reduction plasty: reducing the facial width by performing osteotomy and resecting part of the zygomatic bone and arch
Jaw reduction: reduction of the mandible angle to smooth out an angular jaw and creating a slim jaw
Buccal fat extraction: extraction of the buccal pads
Body contouring: the removal of this excess skin and fat from numerous areas of the body, restoring the appearance of skin elasticity of the remaining skin. The surgery is prominent in those who have undergone significant weight loss resulting in excess sagging skin being present around areas of the body. The skin loses elasticity (a condition called elastosis) once it has been stretched past capacity and is unable to recoil back to its standard position against the body and also with age.
Sclerotherapy: removing visible 'spider veins' (Telangiectasia), which appear on the surface of the skin.
Dermal fillers: Dermal fillers are injected below the skin to give a more fuller, youthful appearance of a feature or section of the face. One type of dermal filler is Hyaluronic acid. Hyaluronic acid is naturally found throughout the human body. It plays a vital role in moving nutrients to the cells of the skin from the blood. It is also commonly used in patients with arthritis as it acts like a cushion to the bones which have depleted the articular cartilage casing. Development within this field has occurred over time with synthetic forms of hyaluronic acid is being created, playing roles in other forms of cosmetic surgery such as facial augmentation.
Micropigmentation: is the creation of permanent makeup using natural pigments to places such as the eyes to create the effect of eye shadow, lips creating lipstick and cheek bones to create a blush like look. The pigment is inserted beneath the skin using a machine which injects a small needle at a very fast rate carrying pigment into the skin, creating a lasting colouration of the desired area. | Plastic surgery | Wikipedia | 414 | 42048 | https://en.wikipedia.org/wiki/Plastic%20surgery | Biology and health sciences | Medical procedures | null |
In 2015, the most popular surgeries were botox, liposuction, blepharoplasties, breast implants, rhynoplasties, and rhytidectomies. According to the 2020 Plastic Surgery Statistics Report, which is published by the American Society of Plastic Surgeons, the most surgical procedure performed in the U.S. was rhinoplasty (nose reshaping) accounting for 15.2% of all cosmetic surgical procedures that year, followed by blepharoplasty (eyelid surgery), which accounted for 14% of all procedures. The third most populous procedure was rhytidectomy (facelift) (10% of all procedures), then liposuction (9.1% of all procedures).
Complications, risks, and reversals
All surgery has risks. Common complications of cosmetic surgery includes hematoma, nerve injury, infection, scarring, implant failure and end organ damage. Breast implants can have many complications, including rupture. In a study of his 4761 augmentation mammaplasty patients, Eisenberg reported that overfilling saline breast implants 10–13% significantly reduced the rupture-deflation rate to 1.83% at 8-years post-implantation. In 2011 FDA stated that one in five patients who received implants for breast augmentation will need them removed within 10 years of implantation.
Psychological disorders
Although media and advertising do play a large role in influencing many people's lives, such as by making people believe plastic surgery to be an acceptable course to change one's identity to their liking, researchers believe that plastic surgery obsession is linked to psychological disorders such as body dysmorphic disorder. There exists a correlation between those with BDD and the predilection toward cosmetic plastic surgery in order to correct a perceived defect in their appearance. | Plastic surgery | Wikipedia | 390 | 42048 | https://en.wikipedia.org/wiki/Plastic%20surgery | Biology and health sciences | Medical procedures | null |
BDD is a disorder resulting in the individual becoming "preoccupied with what they regard as defects in their bodies or faces". Alternatively, where there is a slight physical anomaly, then the person's concern is markedly excessive. While 2% of people have body dysmorphic disorder in the United States, 15% of patients seeing a dermatologist and cosmetic surgeons have the disorder. Half of the patients with the disorder who have cosmetic surgery performed are not pleased with the aesthetic outcome. BDD can lead to suicide in some people with the condition. While many with BDD seek cosmetic surgery, the procedures do not treat BDD, and can ultimately worsen the problem. The psychological root of the problem is usually unidentified; therefore causing the treatment to be even more difficult. Some say that the fixation or obsession with correction of the area could be a sub-disorder such as anorexia or muscle dysmorphia. The increased use of body and facial reshaping applications such as Snapchat and Facetune have been identified as potential triggers of BDD. Recently, a phenomenon referred to as 'Snapchat dysmorphia' has appeared to describe people who request surgery to resemble the edited version of themselves as they appear through Snapchat filters. In response to the detrimental trend, Instagram banned all augmented reality (AR) filters that depict or promote cosmetic surgery.
In some cases, people whose physicians refuse to perform any further surgeries, have turned to "do it yourself" plastic surgery, injecting themselves and facing extreme safety risks. | Plastic surgery | Wikipedia | 318 | 42048 | https://en.wikipedia.org/wiki/Plastic%20surgery | Biology and health sciences | Medical procedures | null |
Mescaline, also known as mescalin or mezcalin, and in chemical terms 3,4,5-trimethoxyphenethylamine, is a naturally occurring psychedelic protoalkaloid of the substituted phenethylamine class, known for its hallucinogenic effects comparable to those of LSD and psilocybin. It binds to and activates certain serotonin receptors in the brain, producing hallucinogenic effects.
Biological sources
It occurs naturally in several species of cacti. It is also reported to be found in small amounts in certain members of the bean family, Fabaceae, including Senegalia berlandieri (syn. Acacia berlandieri), although these reports have been challenged and have been unsupported in any additional analyses.
As shown in the accompanying table, the concentration of mescaline in different specimens can vary largely within a single species. Moreover, the concentration of mescaline within a single specimen varies as well.
History and use
Peyote has been used for at least 5,700 years by Indigenous peoples of the Americas in Mexico. Europeans recorded use of peyote in Native American religious ceremonies upon early contact with the Huichol people in Mexico. Other mescaline-containing cacti such as the San Pedro have a long history of use in South America, from Peru to Ecuador. While religious and ceremonial peyote use was widespread in the Aztec Empire and northern Mexico at the time of the Spanish conquest, religious persecution confined it to areas near the Pacific coast and up to southwest Texas. However, by 1880, peyote use began to spread north of South-Central America with "a new kind of peyote ceremony" inaugurated by the Kiowa and Comanche people. These religious practices, incorporated legally in the United States in 1920 as the Native American Church, have since spread as far as Saskatchewan, Canada. | Mescaline | Wikipedia | 390 | 42052 | https://en.wikipedia.org/wiki/Mescaline | Biology and health sciences | Recreational drugs | Health |
In traditional peyote preparations, the top of the cactus is cut off, leaving the large tap root along with a ring of green photosynthesizing area to grow new heads. These heads are then dried to make disc-shaped buttons. Buttons are chewed to produce the effects or soaked in water to drink. However, the taste of the cactus is bitter, so modern users will often grind it into a powder and pour it into capsules to avoid having to taste it. The typical dosage is 200–400 milligrams of mescaline sulfate or 178–356 milligrams of mescaline hydrochloride. The average peyote button contains about 25 mg mescaline. Some analyses of traditional preparations of San Pedro cactus have found doses ranging from 34 mg to 159 mg of total alkaloids, a relatively low and barely psychoactive amount. It appears that patients who receive traditional treatments with San Pedro ingest sub-psychoactive doses and do not experience psychedelic effects.
Botanical studies of peyote began in the 1840s and the drug was listed in the Mexican pharmacopeia. The first of mescal buttons was published by John Raleigh Briggs in 1887. Mescaline was first isolated and identified in 1896 or 1897 by the German chemist Arthur Heffter and his colleagues. He showed that mescaline was exclusively responsible for the psychoactive or hallucinogenic effects of peyote. However, other components of peyote, such as hordenine, pellotine, and anhalinine, are also active. Mescaline was first synthesized in 1919 by Ernst Späth.
In 1955, English politician Christopher Mayhew took part in an experiment for BBC's Panorama, in which he ingested 400 mg of mescaline under the supervision of psychiatrist Humphry Osmond. Though the recording was deemed too controversial and ultimately omitted from the show, Mayhew praised the experience, calling it "the most interesting thing I ever did".
Studies of the potential therapeutic effects of mescaline started in the 1950s.
The mechanism of action of mescaline, activation of the serotonin 5-HT2A receptors, became known in the 1990s. | Mescaline | Wikipedia | 451 | 42052 | https://en.wikipedia.org/wiki/Mescaline | Biology and health sciences | Recreational drugs | Health |
Potential medical usage
Mescaline has a wide array of suggested medical usage, including treatment of depression, anxiety, PTSD, and alcoholism. However, its status as a Schedule I controlled substance in the Convention on Psychotropic Substances limits availability of the drug to researchers. Because of this, very few studies concerning mescaline's activity and potential therapeutic effects in people have been conducted since the early 1970s.
Behavioral and non-behavioral effects
Mescaline induces a psychedelic state comparable to those produced by LSD and psilocybin, but with unique characteristics. Subjective effects may include altered thinking processes, an altered sense of time and self-awareness, and closed- and open-eye visual phenomena.
Prominence of color is distinctive, appearing brilliant and intense. Recurring visual patterns observed during the mescaline experience include stripes, checkerboards, angular spikes, multicolor dots, and very simple fractals that turn very complex. The English writer Aldous Huxley described these self-transforming amorphous shapes as like animated stained glass illuminated from light coming through the eyelids in his autobiographical book The Doors of Perception (1954). Like LSD, mescaline induces distortions of form and kaleidoscopic experiences but they manifest more clearly with eyes closed and under low lighting conditions.
Heinrich Klüver coined the term "cobweb figure" in the 1920s to describe one of the four form constant geometric visual hallucinations experienced in the early stage of a mescaline trip: "Colored threads running together in a revolving center, the whole similar to a cobweb". The other three are the chessboard design, tunnel, and spiral. Klüver wrote that "many 'atypical' visions are upon close inspection nothing but variations of these form-constants."
As with LSD, synesthesia can occur especially with the help of music. An unusual but unique characteristic of mescaline use is the "geometrization" of three-dimensional objects. The object can appear flattened and distorted, similar to the presentation of a Cubist painting.
Mescaline elicits a pattern of sympathetic arousal, with the peripheral nervous system being a major target for this substance.
According to a research project in the Netherlands, ceremonial San Pedro use seems to be characterized by relatively strong spiritual experiences, and low incidence of challenging experiences. | Mescaline | Wikipedia | 478 | 42052 | https://en.wikipedia.org/wiki/Mescaline | Biology and health sciences | Recreational drugs | Health |
Chemistry
Mescaline, also known as 3,4,5-trimethoxyphenethylamine (3,4,5-TMPEA), is a substituted phenethylamine derivative. It is closely structurally related to the catecholamine neurotransmitters dopamine, norepinephrine, and epinephrine.
The drug is relatively hydrophilic with low fat solubility. Its predicted log P (XLogP3) is 0.7.
Biosynthesis
Mescaline is biosynthesized from tyrosine, which, in turn, is derived from phenylalanine by the enzyme phenylalanine hydroxylase. In Lophophora williamsii (Peyote), dopamine converts into mescaline in a biosynthetic pathway involving m-O-methylation and aromatic hydroxylation.
Tyrosine and phenylalanine serve as metabolic precursors towards the synthesis of mescaline. Tyrosine can either undergo a decarboxylation via tyrosine decarboxylase to generate tyramine and subsequently undergo an oxidation at carbon 3 by a monophenol hydroxylase or first be hydroxylated by tyrosine hydroxylase to form L-DOPA and decarboxylated by DOPA decarboxylase. These create dopamine, which then experiences methylation by a catechol-O-methyltransferase (COMT) by an S-adenosyl methionine (SAM)-dependent mechanism. The resulting intermediate is then oxidized again by a hydroxylase enzyme, likely monophenol hydroxylase again, at carbon 5, and methylated by COMT. The product, methylated at the two meta positions with respect to the alkyl substituent, experiences a final methylation at the 4 carbon by a guaiacol-O-methyltransferase, which also operates by a SAM-dependent mechanism. This final methylation step results in the production of mescaline.
Phenylalanine serves as a precursor by first being converted to L-tyrosine by L-amino acid hydroxylase. Once converted, it follows the same pathway as described above.
Laboratory synthesis | Mescaline | Wikipedia | 483 | 42052 | https://en.wikipedia.org/wiki/Mescaline | Biology and health sciences | Recreational drugs | Health |
Mescaline was first synthesized in 1919 by Ernst Späth from 3,4,5-trimethoxybenzoyl chloride. Several approaches using different starting materials have been developed since, including the following:
Hofmann rearrangement of 3,4,5-trimethoxyphenylpropionamide.
Cyanohydrin reaction between potassium cyanide and 3,4,5-trimethoxybenzaldehyde followed by acetylation and reduction.
Henry reaction of 3,4,5-trimethoxybenzaldehyde with nitromethane followed by nitro compound reduction of ω-nitrotrimethoxystyrene.
Ozonolysis of elemicin followed by reductive amination.
Ester reduction of Eudesmic acid's methyl ester followed by halogenation, Kolbe nitrile synthesis, and nitrile reduction.
Amide reduction of 3,4,5-trimethoxyphenylacetamide.
Reduction of 3,4,5-trimethoxy(2-nitrovinyl)benzene with lithium aluminum hydride.
Treatment of tricarbonyl-(η6-1,2,3-trimethoxybenzene) chromium complex with acetonitrile carbanion in THF and iodine, followed by reduction of the nitrile with lithium aluminum hydride.
Pharmacology
Pharmacodynamics
In plants, mescaline may be the end-product of a pathway utilizing catecholamines as a method of stress response, similar to how animals may release such compounds and others such as cortisol when stressed. The in vivo function of catecholamines in plants has not been investigated, but they may function as antioxidants, as developmental signals, and as integral cell wall components that resist degradation from pathogens. The deactivation of catecholamines via methylation produces alkaloids such as mescaline. | Mescaline | Wikipedia | 421 | 42052 | https://en.wikipedia.org/wiki/Mescaline | Biology and health sciences | Recreational drugs | Health |
In humans, mescaline acts similarly to other psychedelic agents. It acts as an agonist, binding to and activating the serotonin 5-HT2A receptor. Its at the serotonin 5-HT2A receptor is approximately 10,000nM and at the serotonin 5-HT2B receptor is greater than 20,000nM. How activating the 5-HT2A receptor leads to psychedelic effects is still unknown, but it is likely that somehow it involves excitation of neurons in the prefrontal cortex. In addition to the serotonin 5-HT2A and 5-HT2B receptors, mescaline is also known to bind to the serotonin 5-HT2C receptor and a number of other targets.
Mescaline lacks affinity for the monoamine transporters, including the serotonin transporter (SERT), norepinephrine transporter (NET), and dopamine transporter (DAT) (Ki > 30,000nM). However, it has been found to increase levels of the major serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) at high doses in rodents. This finding suggests that mescaline might inhibit the reuptake and/or induce the release of serotonin at such doses. However, this possibility has not yet been further assessed or demonstrated. Besides serotonin, mescaline might also weakly induce the release of dopamine, but this is probably of modest significance, if it occurs. In accordance, there is no evidence of the drug showing addiction or dependence. Other psychedelic phenethylamines, including the closely related 2C, DOx, and TMA drugs, are inactive as monoamine releasing agents and reuptake inhibitors. However, an exception is trimethoxyamphetamine (TMA), the amphetamine analogue of mescaline, which is a very low-potency serotonin releasing agent ( = 16,000nM). The possible monoamine-releasing effects of mescaline would likely be related to its structural similarity to substituted amphetamines and related compounds.
Tolerance to mescaline builds with repeated usage, lasting for a few days. The drug causes cross-tolerance with other serotonergic psychedelics such as LSD and psilocybin. | Mescaline | Wikipedia | 500 | 42052 | https://en.wikipedia.org/wiki/Mescaline | Biology and health sciences | Recreational drugs | Health |
The LD50 of mescaline has been measured in various animals: 212–315 mg/kg i.p. (mice), 132–410 mg/kg i.p. (rats), 328 mg/kg i.p. (guinea pigs), 54mg/kg in dogs, and 130mg/kg i.v. in rhesus macaques. For humans, the LD50 of mescaline has been reported to be approximately 880 mg/kg. It has been said that it would be very difficult to consume enough mescaline to cause death in humans.
Mescaline is a relatively low-potency psychedelic, with active doses in the hundreds of milligrams and micromolar affinities for the serotonin 5-HT2A receptor. For comparison, psilocybin is approximately 20-fold more potent (doses in the tens of milligrams) and lysergic acid diethylamide (LSD) is approximately 2,000-fold more potent (doses in the tens to hundreds of micrograms). There have been efforts to develop more potent analogues of mescaline. Difluoromescaline and trifluoromescaline are more potent than mescaline, as is its amphetamine homologue TMA. Escaline and proscaline are also both more potent than mescaline, showing the importance of the 4-position substituent with regard to receptor binding.
Pharmacokinetics
About half the initial dosage is excreted after 6hours, but some studies suggest that it is not metabolized at all before excretion. Mescaline appears not to be subject to metabolism by CYP2D6 and between 20% and 50% of mescaline is excreted in the urine unchanged, with the rest being excreted as the deaminated-oxidised-carboxylic acid form of mescaline, a likely result of monoamine oxidase (MAO) degradation. However, the enzymes mediating the oxidative deamination of mescaine are controversial. MAO, diamine oxidase (DAO), and/or other enzymes may be involved or responsible. | Mescaline | Wikipedia | 469 | 42052 | https://en.wikipedia.org/wiki/Mescaline | Biology and health sciences | Recreational drugs | Health |
The previously reported elimination half-life of mescaline was originally reported to be 6hours, but a new study published in 2023 reported a half-life of 3.6hours. The higher estimate is believed to be due to small sample numbers and collective measurement of mescaline metabolites.
Mescaline appears to have relatively poor blood–brain barrier permeability due to its low lipophilicity. However, it is still able to cross into the central nervous system and produce psychoactive effects at sufficienty high doses.
Active metabolites of mescaline may contribute to its psychoactive effects.
Legal status
United States
In the United States, mescaline was made illegal in 1970 by the Comprehensive Drug Abuse Prevention and Control Act, categorized as a Schedule I hallucinogen. The drug is prohibited internationally by the 1971 Convention on Psychotropic Substances. Mescaline is legal only for certain religious groups (such as the Native American Church by the American Indian Religious Freedom Act of 1978) and in scientific and medical research. In 1990, the Supreme Court ruled that the state of Oregon could ban the use of mescaline in Native American religious ceremonies. The Religious Freedom Restoration Act (RFRA) in 1993 allowed the use of peyote in religious ceremony, but in 1997, the Supreme Court ruled that the RFRA is unconstitutional when applied against states. Many states, including the state of Utah, have legalized peyote usage with "sincere religious intent", or within a religious organization, regardless of race. Synthetic mescaline, but not mescaline derived from cacti, was officially decriminalized in the state of Colorado by ballot measure Proposition 122 in November 2022.
While mescaline-containing cacti of the genus Echinopsis are technically controlled substances under the Controlled Substances Act, they are commonly sold publicly as ornamental plants.
United Kingdom
In the United Kingdom, mescaline in purified powder form is a Class A drug. However, dried cactus can be bought and sold legally.
Australia
Mescaline is considered a schedule 9 substance in Australia under the Poisons Standard (February 2020). A schedule 9 substance is classified as "Substances with a high potential for causing harm at low exposure and which require special precautions during manufacture, handling or use. These poisons should be available only to specialised or authorised users who have the skills necessary to handle them safely. Special regulations restricting their availability, possession, storage or use may apply." | Mescaline | Wikipedia | 507 | 42052 | https://en.wikipedia.org/wiki/Mescaline | Biology and health sciences | Recreational drugs | Health |
Other countries
In Canada, France, The Netherlands and Germany, mescaline in raw form and dried mescaline-containing cacti are considered illegal drugs. However, anyone may grow and use peyote, or Lophophora williamsii, as well as Echinopsis pachanoi and Echinopsis peruviana without restriction, as it is specifically exempt from legislation. In Canada, mescaline is classified as a schedule III drug under the Controlled Drugs and Substances Act, whereas peyote is exempt.
In Russia mescaline, its derivatives and mescaline-containing plants are banned as narcotic drugs (Schedule I). | Mescaline | Wikipedia | 133 | 42052 | https://en.wikipedia.org/wiki/Mescaline | Biology and health sciences | Recreational drugs | Health |
Notable users
Salvador Dalí experimented with mescaline believing it would enable him to use his subconscious to further his art potential
Antonin Artaud wrote 1947's The Peyote Dance, where he describes his peyote experiences in Mexico a decade earlier.
Jerry Garcia took peyote prior to forming The Grateful Dead but later switched to LSD and DMT since they were easier on the stomach.
Allen Ginsberg took peyote. Part II of his poem "Howl" was inspired by a peyote vision that he had in San Francisco.
Ken Kesey took peyote prior to writing One Flew Over the Cuckoo's Nest.
Jean-Paul Sartre took mescaline shortly before the publication of his first book, L'Imaginaire; he had a bad trip during which he imagined that he was menaced by sea creatures. For many years following this, he persistently thought that he was being followed by lobsters, and became a patient of Jacques Lacan in hopes of being rid of them. Lobsters and crabs figure in his novel Nausea.
Havelock Ellis was the author of one of the first written reports to the public about an experience with mescaline (1898).
Stanisław Ignacy Witkiewicz, Polish writer, artist and philosopher, experimented with mescaline and described his experience in a 1932 book Nikotyna Alkohol Kokaina Peyotl Morfina Eter.
Aldous Huxley described his experience with mescaline in the essay "The Doors of Perception" (1954).
Jim Carroll in The Basketball Diaries described using peyote that a friend smuggled from Mexico.
Quanah Parker, appointed by the federal government as principal chief of the entire Comanche Nation, advocated the syncretic Native American Church alternative, and fought for the legal use of peyote in the movement's religious practices.
Hunter S. Thompson wrote an extremely detailed account of his first use of mescaline in "First Visit with Mescalito", and it appeared in his book Songs of the Doomed, as well as featuring heavily in his novel Fear and Loathing in Las Vegas. | Mescaline | Wikipedia | 433 | 42052 | https://en.wikipedia.org/wiki/Mescaline | Biology and health sciences | Recreational drugs | Health |
Psychedelic research pioneer Alexander Shulgin said he was first inspired to explore psychedelic compounds by a mescaline experience. In 1974, Shulgin synthesized 2C-B, a psychedelic phenylethylamine derivative, structurally similar to mescaline, and one of Shulgin's self-rated most important phenethylamine compounds together with Mescaline, 2C-E, 2C-T-7, and 2C-T-2.
Bryan Wynter produced Mars Ascends after trying the substance for the first time.
George Carlin mentioned mescaline use during his youth while being interviewed in 2008.
Carlos Santana told about his mescaline use in a 1989 Rolling Stone interview.
Disney animator Ward Kimball described participating in a study of mescaline and peyote conducted by UCLA in the 1960s.
Michael Cera used real mescaline for the movie Crystal Fairy & the Magical Cactus, as expressed in an interview.
Philip K. Dick was inspired to write Flow My Tears, the Policeman Said after taking mescaline.
Arthur Kleps, a psychologist turned drug legalization advocate and writer whose Neo-American Church defended use of marijuana and hallucinogens such as LSD and peyote for spiritual enlightenment and exploration, bought, in 1960, by mail from Delta Chemical Company in New York 1 g of mescaline sulfate and took 500 mg. He experienced a psychedelic trip that caused profound changes in his life and outlook. | Mescaline | Wikipedia | 300 | 42052 | https://en.wikipedia.org/wiki/Mescaline | Biology and health sciences | Recreational drugs | Health |
Hydrogen cyanide (formerly known as prussic acid) is a chemical compound with the formula HCN and structural formula . It is a highly toxic and flammable liquid that boils slightly above room temperature, at . HCN is produced on an industrial scale and is a highly valued precursor to many chemical compounds ranging from polymers to pharmaceuticals. Large-scale applications are for the production of potassium cyanide and adiponitrile, used in mining and plastics, respectively. It is more toxic than solid cyanide compounds due to its volatile nature. A solution of hydrogen cyanide in water, represented as HCN, is called hydrocyanic acid. The salts of the cyanide anion are known as cyanides.
Whether hydrogen cyanide is an organic compound or not is a topic of debate among chemists, and opinions vary from author to author. Traditionally, it is considered inorganic by a significant number of authors. Contrary to this view, it is considered organic by other authors, because hydrogen cyanide belongs to the class of organic compounds known as nitriles which have the formula , where R is typically organyl group (e.g., alkyl or aryl) or hydrogen. In the case of hydrogen cyanide, the R group is hydrogen H, so the other names of hydrogen cyanide are methanenitrile and formonitrile.
Structure and general properties
Hydrogen cyanide is a linear molecule, with a triple bond between carbon and nitrogen. The tautomer of HCN is HNC, hydrogen isocyanide.
HCN has a faint bitter almond-like odor that some people are unable to detect owing to a recessive genetic trait. The volatile compound has been used as inhalation rodenticide and human poison, as well as for killing whales. Cyanide ions interfere with iron-containing respiratory enzymes.
Chemical properties
Hydrogen cyanide is weakly acidic with a pKa of 9.2. It partially ionizes in water to give the cyanide anion, . HCN forms hydrogen bonds with its conjugate base, species such as .
Hydrogen cyanide reacts with alkenes to give nitriles. The conversion, which is called hydrocyanation, employs nickel complexes as catalysts.
Four molecules of HCN will tetramerize into diaminomaleonitrile. | Hydrogen cyanide | Wikipedia | 490 | 42078 | https://en.wikipedia.org/wiki/Hydrogen%20cyanide | Physical sciences | Hydrogen compounds | Chemistry |
Metal cyanides are typically prepared by salt metathesis from alkali metal cyanide salts, but mercuric cyanide is formed from aqueous hydrogen cyanide:
History of discovery and naming
Hydrogen cyanide was first isolated in 1752 by French chemist Pierre Macquer who converted Prussian blue to an iron oxide plus a volatile component and found that these could be used to reconstitute it. The new component was what is now known as hydrogen cyanide. It was subsequently prepared from Prussian blue by the Swedish chemist Carl Wilhelm Scheele in 1782, and was eventually given the German name Blausäure (lit. "Blue acid") because of its acidic nature in water and its derivation from Prussian blue. In English, it became known popularly as prussic acid.
In 1787, the French chemist Claude Louis Berthollet showed that prussic acid did not contain oxygen, an important contribution to acid theory, which had hitherto postulated that acids must contain oxygen (hence the name of oxygen itself, which is derived from Greek elements that mean "acid-former" and are likewise calqued into German as Sauerstoff).
In 1811, Joseph Louis Gay-Lussac prepared pure, liquified hydrogen cyanide, and in 1815 he deduced Prussic acid's chemical formula.
Etymology
The word cyanide for the radical in hydrogen cyanide was derived from its French equivalent, cyanure, which Gay-Lussac constructed from the Ancient Greek word κύανος for dark blue enamel or lapis lazuli, again owing to the chemical’s derivation from Prussian blue. Incidentally, the Greek word is also the root of the English color name cyan.
Production and synthesis
The most important process is the Andrussow oxidation invented by Leonid Andrussow at IG Farben in which methane and ammonia react in the presence of oxygen at about over a platinum catalyst:
In 2006, between 500 million and 1 billion pounds (between 230,000 and 450,000 t) were produced in the US. Hydrogen cyanide is produced in large quantities by several processes and is a recovered waste product from the manufacture of acrylonitrile.
Of lesser importance is the Degussa process (BMA process) in which no oxygen is added and the energy must be transferred indirectly through the reactor wall: | Hydrogen cyanide | Wikipedia | 491 | 42078 | https://en.wikipedia.org/wiki/Hydrogen%20cyanide | Physical sciences | Hydrogen compounds | Chemistry |
This reaction is akin to steam reforming, the reaction of methane and water to give carbon monoxide and hydrogen.
In the Shawinigan Process, hydrocarbons, e.g. propane, are reacted with ammonia.
In the laboratory, small amounts of HCN are produced by the addition of acids to cyanide salts of alkali metals:
This reaction is sometimes the basis of accidental poisonings because the acid converts a nonvolatile cyanide salt into the gaseous HCN.
Hydrogen cyanide could be obtained from potassium ferricyanide and acid:
Historical methods of production
The large demand for cyanides for mining operations in the 1890s was met by George Thomas Beilby, who patented a method to produce hydrogen cyanide by passing ammonia over glowing coal in 1892. This method was used until Hamilton Castner in 1894 developed a synthesis starting from coal, ammonia, and sodium yielding sodium cyanide, which reacts with acid to form gaseous HCN.
Applications
HCN is the precursor to sodium cyanide and potassium cyanide, which are used mainly in gold and silver mining and for the electroplating of those metals. Via the intermediacy of cyanohydrins, a variety of useful organic compounds are prepared from HCN including the monomer methyl methacrylate, from acetone, the amino acid methionine, via the Strecker synthesis, and the chelating agents EDTA and NTA. Via the hydrocyanation process, HCN is added to butadiene to give adiponitrile, a precursor to Nylon-6,6.
HCN is used globally as a fumigant against many species of pest insects that infest food production facilities. Both its efficacy and method of application lead to very small amounts of the fumigant being used compared to other toxic substances used for the same purpose. Using HCN as a fumigant also has less environmental impact, compared to some other fumigants such as sulfuryl fluoride, and methyl bromide. | Hydrogen cyanide | Wikipedia | 424 | 42078 | https://en.wikipedia.org/wiki/Hydrogen%20cyanide | Physical sciences | Hydrogen compounds | Chemistry |
Occurrence
HCN is obtainable from fruits that have a pit, such as cherries, apricots, apples, and nuts such as bitter almonds, from which almond oil and extract is made. Many of these pits contain small amounts of cyanohydrins such as mandelonitrile and amygdalin, which slowly release hydrogen cyanide. One hundred grams of crushed apple seeds can yield about 70 mg of HCN. The roots of cassava plants contain cyanogenic glycosides such as linamarin, which decompose into HCN in yields of up to 370 mg per kilogram of fresh root. Some millipedes, such as Harpaphe haydeniana, Desmoxytes purpurosea, and Apheloria release hydrogen cyanide as a defense mechanism, as do certain insects, such as burnet moths and the larvae of Paropsisterna eucalyptus. Hydrogen cyanide is contained in the exhaust of vehicles, and in smoke from burning nitrogen-containing plastics.
On Titan
HCN has been measured in Titan's atmosphere by four instruments on the Cassini space probe, one instrument on Voyager, and one instrument on Earth. One of these measurements was in situ, where the Cassini spacecraft dipped between above Titan's surface to collect atmospheric gas for mass spectrometry analysis. HCN initially forms in Titan's atmosphere through the reaction of photochemically produced methane and nitrogen radicals which proceed through the H2CN intermediate, e.g., (CH3 + N → H2CN + H → HCN + H2). Ultraviolet radiation breaks HCN up into CN + H; however, CN is efficiently recycled back into HCN via the reaction CN + CH4 → HCN + CH3.
On the young Earth
It has been postulated that carbon from a cascade of asteroids (known as the Late Heavy Bombardment), resulting from interaction of Jupiter and Saturn, blasted the surface of young Earth and reacted with nitrogen in Earth's atmosphere to form HCN. | Hydrogen cyanide | Wikipedia | 419 | 42078 | https://en.wikipedia.org/wiki/Hydrogen%20cyanide | Physical sciences | Hydrogen compounds | Chemistry |
In mammals
Some authors have shown that neurons can produce hydrogen cyanide upon activation of their opioid receptors by endogenous or exogenous opioids. They have also shown that neuronal production of HCN activates NMDA receptors and plays a role in signal transduction between neuronal cells (neurotransmission). Moreover, increased endogenous neuronal HCN production under opioids was seemingly needed for adequate opioid analgesia, as analgesic action of opioids was attenuated by HCN scavengers. They considered endogenous HCN to be a neuromodulator.
It has also been shown that, while stimulating muscarinic cholinergic receptors in cultured pheochromocytoma cells increases HCN production, in a living organism (in vivo) muscarinic cholinergic stimulation actually decreases HCN production.
Leukocytes generate HCN during phagocytosis, and can kill bacteria, fungi, and other pathogens by generating several different toxic chemicals, one of which is hydrogen cyanide.
The vasodilatation caused by sodium nitroprusside has been shown to be mediated not only by NO generation, but also by endogenous cyanide generation, which adds not only toxicity, but also some additional antihypertensive efficacy compared to nitroglycerine and other non-cyanogenic nitrates which do not cause blood cyanide levels to rise.
HCN is a constituent of tobacco smoke.
HCN and the origin of life
Hydrogen cyanide has been discussed as a precursor to amino acids and nucleic acids, and is proposed to have played a part in the origin of life. Although the relationship of these chemical reactions to the origin of life theory remains speculative, studies in this area have led to discoveries of new pathways to organic compounds derived from the condensation of HCN (e.g. Adenine). That's why scientists who search for life on planets beyond Earth, the primary factors they examine, after confirming suitable temperatures and the presence of water, are molecules like hydrogen cyanide.
In space | Hydrogen cyanide | Wikipedia | 449 | 42078 | https://en.wikipedia.org/wiki/Hydrogen%20cyanide | Physical sciences | Hydrogen compounds | Chemistry |
HCN has been detected in the interstellar medium and in the atmospheres of carbon stars. Since then, extensive studies have probed formation and destruction pathways of HCN in various environments and examined its use as a tracer for a variety of astronomical species and processes. HCN can be observed from ground-based telescopes through a number of atmospheric windows. The J=1→0, J=3→2, J= 4→3, and J=10→9 pure rotational transitions have all been observed.
HCN is formed in interstellar clouds through one of two major pathways: via a neutral-neutral reaction (CH2 + N → HCN + H) and via dissociative recombination (HCNH+ + e− → HCN + H). The dissociative recombination pathway is dominant by 30%; however, the HCNH+ must be in its linear form. Dissociative recombination with its structural isomer, H2NC+, exclusively produces hydrogen isocyanide (HNC).
HCN is destroyed in interstellar clouds through a number of mechanisms depending on the location in the cloud. In photon-dominated regions (PDRs), photodissociation dominates, producing CN (HCN + ν → CN + H). At further depths, photodissociation by cosmic rays dominate, producing CN (HCN + cr → CN + H). In the dark core, two competing mechanisms destroy it, forming HCN+ and HCNH+ (HCN + H+ → HCN+ + H; HCN + HCO+ → HCNH+ + CO). The reaction with HCO+ dominates by a factor of ~3.5. HCN has been used to analyze a variety of species and processes in the interstellar medium. It has been suggested as a tracer for dense molecular gas and as a tracer of stellar inflow in high-mass star-forming regions. Further, the HNC/HCN ratio has been shown to be an excellent method for distinguishing between PDRs and X-ray-dominated regions (XDRs). | Hydrogen cyanide | Wikipedia | 442 | 42078 | https://en.wikipedia.org/wiki/Hydrogen%20cyanide | Physical sciences | Hydrogen compounds | Chemistry |
On 11 August 2014, astronomers released studies, using the Atacama Large Millimeter/Submillimeter Array (ALMA) for the first time, that detailed the distribution of HCN, HNC, H2CO, and dust inside the comae of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON).
In February 2016, it was announced that traces of hydrogen cyanide were found in the atmosphere of the hot Super-Earth 55 Cancri e with NASA's Hubble Space Telescope.
On 14 December 2023, astronomers reported the first time discovery, in the plumes of Enceladus, moon of the planet Saturn, of hydrogen cyanide, a possible chemical essential for life as we know it, as well as other organic molecules, some of which are yet to be better identified and understood. According to the researchers, "these [newly discovered] compounds could potentially support extant microbial communities or drive complex organic synthesis leading to the origin of life."
As a poison and chemical weapon
In World War I, hydrogen cyanide was used by the French from 1916 as a chemical weapon against the Central Powers, and by the United States and Italy in 1918. It was not found to be effective enough due to weather conditions. The gas is lighter than air and rapidly disperses up into the atmosphere. Rapid dilution made its use in the field impractical. In contrast, denser agents such as phosgene or chlorine tended to remain at ground level and sank into the trenches of the Western Front's battlefields. Compared to such agents, hydrogen cyanide had to be present in higher concentrations in order to be fatal.
A hydrogen cyanide concentration of 100–200 ppm in breathing air will kill a human within 10 to 60 minutes. A hydrogen cyanide concentration of 2000 ppm (about 2380 mg/m3) will kill a human in about one minute. The toxic effect is caused by the action of the cyanide ion, which halts cellular respiration. It acts as a non-competitive inhibitor for an enzyme in mitochondria called cytochrome c oxidase. As such, hydrogen cyanide is commonly listed among chemical weapons as a blood agent. | Hydrogen cyanide | Wikipedia | 466 | 42078 | https://en.wikipedia.org/wiki/Hydrogen%20cyanide | Physical sciences | Hydrogen compounds | Chemistry |
The Chemical Weapons Convention lists it under Schedule 3 as a potential weapon which has large-scale industrial uses. Signatory countries must declare manufacturing plants that produce more than 30 metric tons per year, and allow inspection by the Organisation for the Prohibition of Chemical Weapons.
Perhaps its most infamous use is (German: Cyclone B, with the B standing for – prussic acid; also, to distinguish it from an earlier product later known as Zyklon A), used in the Nazi German extermination camps of Majdanek and Auschwitz-Birkenau during World War II to kill Jews and other persecuted minorities en masse as part of their Final Solution genocide program. Hydrogen cyanide was also used in the camps for delousing clothing in attempts to eradicate diseases carried by lice and other parasites. One of the original Czech producers continued making Zyklon B under the trademark "Uragan D2" until around 2015.
During World War II, the US considered using it, along with cyanogen chloride, as part of Operation Downfall, the planned invasion of Japan, but President Harry Truman decided against it, instead using the atomic bombs developed by the secret Manhattan Project.
Hydrogen cyanide was also the agent employed in judicial execution in some U.S. states, where it was produced during the execution by the action of sulfuric acid on sodium cyanide or potassium cyanide.
Under the name prussic acid, HCN has been used as a killing agent in whaling harpoons, although it proved quite dangerous to the crew deploying it, and it was quickly abandoned. From the middle of the 18th century it was used in a number of poisoning murders and suicides.
Hydrogen cyanide gas in air is explosive at concentrations above 5.6%. | Hydrogen cyanide | Wikipedia | 363 | 42078 | https://en.wikipedia.org/wiki/Hydrogen%20cyanide | Physical sciences | Hydrogen compounds | Chemistry |
Potassium hexacyanidoferrate(II) is the inorganic compound with formula K4[Fe(CN)6]·3H2O. It is the potassium salt of the coordination complex [Fe(CN)6]4−. This salt forms lemon-yellow monoclinic crystals.
Synthesis
In 1752, the French chemist Pierre Joseph Macquer (1718–1784) first reported the preparation of Potassium hexacyanidoferrate(II), which he achieved by reacting Prussian blue (iron(III) ferrocyanide) with potassium hydroxide.
Modern production
Potassium hexacyanidoferrate(II) is produced industrially from hydrogen cyanide, iron(II) chloride, and calcium hydroxide, the combination of which affords Ca2[Fe(CN)6]·11H2O. This solution is then treated with potassium salts to precipitate the mixed calcium-potassium salt CaK2[Fe(CN)6], which in turn is treated with potassium carbonate to give the tetrapotassium salt.
Historical production
Historically, the compound was manufactured from nitrogenous organic material, iron filings, and potassium carbonate. Common nitrogen and carbon sources were torrified horn, leather scrap, offal, or dried blood. It was also obtained commercially from gasworks spent oxide (purification of city gas from hydrogen cyanide).
Chemical reactions
Treatment of potassium hexacyanidoferrate(II) with nitric acid gives H2[Fe(NO)(CN)5]. After neutralization of this intermediate with sodium carbonate, red crystals of sodium nitroprusside can be selectively crystallized.
Upon treatment with chlorine gas, potassium hexacyanidoferrate(II) converts to potassium hexacyanidoferrate(III):
2 K4[Fe(CN)6] + Cl2 → 2 K3[Fe(CN)6] + 2 KCl
This reaction can be used to remove potassium hexacyanidoferrate(II) from a solution.
A famous reaction involves treatment with ferric salts, most commonly Iron(III) chloride, to give Prussian blue. In the reaction with Iron(III) chloride, producing Potassium chloride as a side-product:
3 K4[Fe(CN)6] + 4 FeCl3 → Fe4[Fe(CN)6]3 + 12 KCl | Potassium ferrocyanide | Wikipedia | 502 | 42079 | https://en.wikipedia.org/wiki/Potassium%20ferrocyanide | Physical sciences | Cyanide salts | Chemistry |
With the composition Fe[Fe(CN)], this insoluble but deeply coloured material is the blue of blueprinting, as well as on many famous paintings such as The Great Wave off Kanagawa and The Starry Night.
Applications
Potassium hexacyanidoferrate(II) finds many niche applications in industry. It and the related sodium salt are widely used as anticaking agents for both road salt and table salt. The potassium and sodium hexacyanidoferrates(II) are also used in the purification of tin and the separation of copper from molybdenum ores. Potassium hexacyanidoferrate(II) is used in the production of wine and citric acid.
In the EU, hexacyanidoferrates(II) (E 535–538) were, as of 2017, solely authorised in two food categories as salt additives.
It can also be used in animal feed.
In the laboratory, potassium hexacyanidoferrate(II) is used to determine the concentration of potassium permanganate, a compound often used in titrations based on redox reactions. Potassium hexacyanidoferrate(II) is used in a mixture with potassium ferricyanide and phosphate buffered solution to provide a buffer for beta-galactosidase, which is used to cleave X-Gal, giving a bright blue visualization where an antibody (or other molecule), conjugated to Beta-gal, has bonded to its target. On reacting with Fe(3) it gives a Prussian blue colour. Thus it is used as an identifying reagent for iron in labs.
Potassium hexacyanidoferrate(II) can be used as a fertilizer for plants.
Prior to 1900, before the invention of the Castner process, potassium hexacyanidoferrate(II) was the most important source of alkali metal cyanides. In this historical process, potassium cyanide was produced by decomposing potassium hexacyanidoferrate(II):
K4[Fe(CN)6] → 4 KCN + FeC2 + N2 | Potassium ferrocyanide | Wikipedia | 455 | 42079 | https://en.wikipedia.org/wiki/Potassium%20ferrocyanide | Physical sciences | Cyanide salts | Chemistry |
Structure
Like other metal cyanides, solid potassium hexacyanidoferrate(II), both as the hydrate and anhydrous salts, has a complicated polymeric structure. The polymer consists of octahedral [Fe(CN)6]4− centers crosslinked with K+ ions that are bound to the CN ligands. The K+---NC linkages break when the solid is dissolved in water.
Toxicity
The toxicity in rats is low, with lethal dose (LD50) at 6400 mg/kg. The kidneys are the organ for ferrocyanide toxicity. | Potassium ferrocyanide | Wikipedia | 128 | 42079 | https://en.wikipedia.org/wiki/Potassium%20ferrocyanide | Physical sciences | Cyanide salts | Chemistry |
The Atlantic cod (: cod; Gadus morhua) is a fish of the family Gadidae, widely consumed by humans. It is also commercially known as cod or codling.
In the western Atlantic Ocean, cod has a distribution north of Cape Hatteras, North Carolina, and around both coasts of Greenland and the Labrador Sea; in the eastern Atlantic, it is found from the Bay of Biscay north to the Arctic Ocean, including the Baltic Sea, the North Sea, Sea of the Hebrides, areas around Iceland and the Barents Sea.
Atlantic cod can live for up to 25 years and typically grow up to , but individuals in excess of and have been caught. They will attain sexual maturity between ages two and eight with this varying between populations and has varied over time.
Colouring is brown or green, with spots on the dorsal side, shading to silver ventrally. A stripe along its lateral line (used to detect vibrations) is clearly visible. Its habitat ranges from the coastal shoreline down to along the continental shelf.
Atlantic cod is one of the most heavily fished species. Atlantic cod was fished for a thousand years by north European fishers who followed it across the North Atlantic Ocean to North America. It supported the US and Canada fishing economy until 1992, when the Canadian Government implemented a ban on fishing cod.
Several cod stocks collapsed in the 1990s (decline of more than 95% of maximum historical biomass) and have failed to fully recover even with the cessation of fishing. This absence of the apex predator has led to a trophic cascade in many areas. Many other cod stocks remain at risk. The Atlantic cod is labelled vulnerable on the IUCN Red List of Threatened Species, per a 1996 assessment that the IUCN notes needs updating. A 2013 assessment covering only Europe shows the Atlantic cod has rebounded in Europe, and it has been relabelled least concern.
Dry cod may be prepared as unsalted stockfish, and as cured salt cod or clipfish.
Taxonomy
The Atlantic cod is one of three cod species in the genus Gadus along with Pacific cod and Greenland cod. A variety of fish species are colloquially known as cod, but they are not all classified within the Gadus, though some are in the Atlantic cod family, Gadidae.
Behaviour
Shoaling | Atlantic cod | Wikipedia | 465 | 42080 | https://en.wikipedia.org/wiki/Atlantic%20cod | Biology and health sciences | Acanthomorpha | Animals |
Atlantic cod are a shoaling species and move in large, size-structured aggregations. Larger fish act as scouts and lead the shoal's direction, particularly during post spawning migrations inshore for feeding. Cod actively feed during migration and changes in shoal structure occur when food is encountered. Shoals are generally thought to be relatively leaderless, with all fish having equal status and an equal distribution of resources and benefits. However, some studies suggest that leading fish gain certain feeding benefits. One study of a migrating Atlantic cod shoal showed significant variability in feeding habits based on size and position in the shoal. Larger scouts consumed a more variable, higher quantity of food, while trailing fish had less variable diets and consumed less food. Fish distribution throughout the shoal seems to be dictated by fish size, and ultimately, the smaller lagging fish likely benefit from shoaling because they are more successful in feeding in the shoal than they would be if migrating individually, due to social facilitation.
Predation
Atlantic cod are apex predators in the Baltic and adults are generally free from the concerns of predation. Juvenile cod, however, may serve as prey for adult cod, which sometimes practice cannibalism. Juvenile cod make substrate decisions based on risk of predation. Substrates refer to different feeding and swimming environments. Without apparent risk of predation, juvenile cod demonstrated a preference for finer-grained substrates such as sand and gravel-pebble. However, in the presence of a predator, they preferred to seek safety in the space available between stones of a cobble substrate. Selection of cobble significantly reduces the risk of predation. Without access to cobble, the juvenile cod simply tries to escape a predator by fleeing.
Additionally, juvenile Atlantic cod vary their behaviour according to the foraging behaviour of predators. In the vicinity of a passive predator, cod behaviour changes very little. The juveniles prefer finer-grained substrates and otherwise avoid the safer kelp, steering clear of the predator. In contrast, in the presence of an actively foraging predator, juveniles are highly avoidant and hide in cobble or in kelp if cobble is unavailable. | Atlantic cod | Wikipedia | 434 | 42080 | https://en.wikipedia.org/wiki/Atlantic%20cod | Biology and health sciences | Acanthomorpha | Animals |
Heavy fishing of cod in the 1990s and the collapse of American and Canadian cod stocks resulted in trophic cascades. As cod are apex predators, overfishing them removed a significant predatory pressure on other Atlantic fish and crustacean species. Population-limiting effects on several species including American lobsters, crabs, and shrimp from cod predation have decreased significantly, and the abundance of these species and their increasing range serve as evidence of the Atlantic cod's role as a major predator rather than prey.
Swimming
Atlantic cod have been recorded to swim at speeds of a minimum of and a maximum of with a mean swimming speed of . In one hour, cod have been recorded to cover a mean range of . Swimming speed was higher during the day than at night. This is reflected in the fact that cod more actively search for food during the day. Cod likely modify their activity pattern according to the length of daylight, thus activity varies with time of year.
Response to changing temperatures
Swimming and physiological behaviours change in response to fluctuations in water temperature. Respirometry experiments show that heart rates of Atlantic cod change drastically with changes in temperature of only a few degrees. A rise in water temperature causes marked increases in cod swimming activity. Cod typically avoid new temperature conditions, and the temperatures can dictate where they are distributed in water. They prefer to be deeper, in colder water layers during the day, and in shallower, warmer water layers at night. These fine-tuned behavioural changes to water temperature are driven by an effort to maintain homeostasis to preserve energy. This is demonstrated by the fact that a decrease of only caused a highly costly increase in metabolic rate of 15–30%. | Atlantic cod | Wikipedia | 341 | 42080 | https://en.wikipedia.org/wiki/Atlantic%20cod | Biology and health sciences | Acanthomorpha | Animals |
Feeding and diet
The diet of the Atlantic cod consists of fish such as herring, capelin (in the Eastern Atlantic Ocean), and sand eels, as well as mollusks, tunicates, comb jellies, crustaceans, echinoderms and sea worms. Stomach sampling studies have discovered that small Atlantic cod feed primarily on crustaceans, while large Atlantic cod feed primarily on fish. In certain regions, the main food source is decapods with fish as a complementary food item in the diet. Wild Atlantic cod throughout the North Sea depend, to a large extent, on commercial fish species also used in fisheries, such as Atlantic mackerel, haddock, whiting, Atlantic herring, European plaice, and common sole, making fishery manipulation of cod significantly easier. Ultimately, food selection by cod is affected by the food item size relative to their own size. However, providing for size, cod do exhibit food preference and are not simply driven by availability.
Atlantic cod practice some cannibalism. In the southern North Sea, 1–2% (by weight) of stomach contents for cod larger than consisted of juvenile cod. In the northern North Sea, cannibalism was higher, at 10%. Other reports of cannibalism have estimated as high as 56% of the diet consists of juvenile cod.
When hatched, cod larvae are altricial, entirely dependent on a yolk sac for sustenance until mouth opening at ~24 degree days. The stomach generally develops at around 240 degree days. Before this point the intestine is the main point of food digestion using pancreatic enzymes such as trypsin.
Reproduction | Atlantic cod | Wikipedia | 341 | 42080 | https://en.wikipedia.org/wiki/Atlantic%20cod | Biology and health sciences | Acanthomorpha | Animals |
Atlantic cod will attain sexual maturity between ages two and eight with this varying between different populations and has also varied over time with a population. Their gonads take several months to develop and most populations will spawn from January to May. For many populations, the spawning grounds are located in a different area than the feeding grounds so require the fish to migrate in order to spawn. On the spawning area, males and females will form large schools. Based on behavioral observations of cod, the cod mating system has been likened to a lekking system, which is characterized by males aggregating and establishing dominance hierarchies, at which point females may visit and choose a spawning partner based on status and sexual characteristics. Evidence suggests male sound production and other sexually selected characteristics allow female cod to actively choose a spawning partner. Males also exhibit aggressive interactions for access to females.
Atlantic cod are batch spawners, in which females will spawn approximately 5–20 batches of eggs over a period of time with 2–4 days between the release of each batch. Each female will spawn between 2 hundred thousand and 15 million eggs, with larger females spawning more eggs. Females release gametes in a ventral mount, and males then fertilize the released eggs. The eggs and newly hatched larvae float freely in the water and will drift with the current, with some populations relying upon the current to transport the larvae to nursery areas.
Parasites
Atlantic cod act as intermediate, paratenic, or definitive hosts to a large number of parasite species: 107 taxa listed by Hemmingsen and MacKenzie (2001) and seven new records by Perdiguero-Alonso et al. (2008). The predominant groups of cod parasites in the northeast Atlantic were trematodes (19 species) and nematodes (13 species), including larval anisakids, which comprised 58.2% of the total number of individuals. Parasites of Atlantic cod include copepods, digeneans, monogeneans, acanthocephalans, cestodes, nematodes, myxozoans, and protozoans.
Fisheries | Atlantic cod | Wikipedia | 428 | 42080 | https://en.wikipedia.org/wiki/Atlantic%20cod | Biology and health sciences | Acanthomorpha | Animals |
Atlantic cod has been targeted by humans for food for thousands of years, and with the advent of modern fishing technology in the 1950s there was a rapid rise in landings. Cod is caught using a variety of fishing gears including bottom trawls, demersal longlines, Danish seine, jigging and hand lines. The quantity of cod landed from fisheries has been recorded by many countries from around the 1950s and attempts have been made to reconstruct historical catches going back hundreds of years. ICES and NAFO collects landings data, alongside other data, which is used to assess the status of the population against management objectives. The landings in the eastern Atlantic frequently exceeds 1 million tonnes annually from across 16 populations/management units with landings from the Northeast Atlantic cod population and Iceland accounting for the majority of the landings, Since 1992, when the cod moratorium took effect in Canada, landings in the western Atlantic have been considerably lower than in the eastern Atlantic, generally being less than 50,000 tonnes annually.
Northwest Atlantic cod
The Northwest Atlantic cod has been regarded as heavily overfished throughout its range, resulting in a crash in the fishery in the United States and Canada during the early 1990s.
Newfoundland's northern cod fishery can be traced back to the 16th century. On average, about of cod were landed annually until the 1960s, when advances in technology enabled factory trawlers to take larger catches. By 1968, landings for the fish peaked at before a gradual decline set in. With the reopening of the limited cod fisheries in 2006, nearly of cod were hauled in. In 2007, offshore cod stocks were estimated at 1% of what they were in 1977.Technologies that contributed to the collapse of Atlantic cod include engine-powered vessels and frozen food compartments aboard ships. Engine-powered vessels had larger nets, greater range, and better navigation. The capacity to catch fish became limitless. In addition, sonar technology gave an edge to detecting and catching fish. Sonar was originally developed during World War II to locate enemy submarines, but was later applied to locating schools of fish. These new technologies, as well as bottom trawlers that destroyed entire ecosystems, contributed to the collapse of Atlantic cod. They were vastly different from old techniques used, such as hand lines and long lines. | Atlantic cod | Wikipedia | 455 | 42080 | https://en.wikipedia.org/wiki/Atlantic%20cod | Biology and health sciences | Acanthomorpha | Animals |
The fishery has only recently begun to recover, and may never fully recover because of a possibly stable change in the food chain. Atlantic cod was a top-tier predator, along with haddock, flounder and hake, feeding upon smaller prey, such as herring, capelin, shrimp, and snow crab. With the large predatory fish removed, their prey have had population explosions and have become the top predators, affecting the survival rates of cod eggs and fry.
In the winter of 2011–2012, the cod fishery succeeded in convincing NOAA to postpone for one year the planned 82% reduction in catch limits. Instead, the limit was reduced by 22%. The fishery brought in $15.8 million in 2010, coming second behind Georges Bank haddock among the region's 20 regulated bottom-dwelling groundfish. Data released in 2011 indicated that even closing the fishery would not allow populations to rebound by 2014 to levels required under federal law. Restrictions on cod effectively limit fishing on other groundfish species with which the cod swim, such as flounder and haddock.
Northeast Atlantic cod
The Northeast Atlantic has the world's largest population of cod. By far, the largest part of this population is the Northeast Arctic cod, as it is labelled by the ICES, or the Arcto-Norwegian cod stock, also referred to as skrei, a Norwegian name meaning something like "the wanderer", distinguishing it from coastal cod. The Northeast Arctic cod is found in the Barents Sea area. This stock spawns in March and April along the Norwegian coast, about 40% around the Lofoten archipelago. Newly hatched larvae drift northwards with the coastal current while feeding on larval copepods. By summer, the young cod reach the Barents Sea, where they stay for the rest of their lives, until their spawning migration. As the cod grow, they feed on krill and other small crustaceans and fish. Adult cod primarily feed on fish such as capelin and herring. The northeast Arctic cod also show cannibalistic behaviour. Estimated stock size was in 2008. | Atlantic cod | Wikipedia | 425 | 42080 | https://en.wikipedia.org/wiki/Atlantic%20cod | Biology and health sciences | Acanthomorpha | Animals |
The North Sea cod stock is primarily fished by European Union member states, the United Kingdom and Norway. In 1999, the catch was divided among Denmark (31%), Scotland (25%), the rest of the United Kingdom (12%), the Netherlands (10%), Belgium, Germany and Norway (17%). In the 1970s, the annual catch rose to between . Due to concerns about overfishing, catch quotas were repeatedly reduced in the 1980s and 1990s. In 2003, ICES stated a high risk existed of stock collapse if then current exploitation levels continued, and recommended a moratorium on catching Atlantic cod in the North Sea during 2004. However, agriculture and fisheries ministers from the Council of the European Union endorsed the EU/Norway Agreement and set the total allowable catch at . Seafood sustainability guides, such as the Monterey Bay Aquarium's Seafood Watch, often recommend environmentally conscious customers not purchase Atlantic cod.
The stock of Northeast Arctic cod was more than four million tons following World War II, but declined to a historic minimum of in 1983. The catch reached a historic maximum of in 1956, and bottomed out at in 1990. Since 2000, the spawning stock has increased quite quickly, helped by low fishing pressure. The total catch in 2012 was , the major fishers being Norway and Russia.
Baltic cod
Decades of overfishing in combination with environmental problems, namely little water exchange, low salinity and oxygen-depletion at the sea bottom, caused major threats to the Baltic cod stocks.
There are at least two populations of cod in the Baltic Sea: One large population that spawns east of Bornholm and one population spawning west of Bornholm. Eastern Baltic cod is genetically distinct and adapted to the brackish environment. Adaptations include differences in hemoglobin type, osmoregulatory capacity, egg buoyancy, sperm swimming characteristics and spawning season. The adaptive responses to the environmental conditions in the Baltic Sea may contribute to an effective reproductive barrier, and thus, eastern Baltic cod can be viewed as an example of ongoing speciation. Due to drastically low cod population sizes, commercial fishing of eastern Baltic cod is prohibited since 2019. However, unfavourable environmental conditions in the eastern Baltic Sea, i.e., low salinity and increasing oxygen-depletion at the sea bottom, led to presently only the Bornholm Basin (Southern Baltic Sea) having sufficient conditions for successful reproduction of eastern Baltic cod. | Atlantic cod | Wikipedia | 497 | 42080 | https://en.wikipedia.org/wiki/Atlantic%20cod | Biology and health sciences | Acanthomorpha | Animals |
The western Baltic cod consists of one or several small subpopulations that are genetically more similar to the North Sea cod. In the Arkona basin (located off Cape Arkona, Rügen), spawning and migrating cod from both the eastern and western stocks intermingle in proportions that vary seasonally. The immigration of eastern cod into the western Baltic management unit may mask a poor state of the populations in the western management unit. | Atlantic cod | Wikipedia | 87 | 42080 | https://en.wikipedia.org/wiki/Atlantic%20cod | Biology and health sciences | Acanthomorpha | Animals |
Salmonella is a genus of rod-shaped, (bacillus) gram-negative bacteria of the family Enterobacteriaceae. The two known species of Salmonella are Salmonella enterica and Salmonella bongori. S. enterica is the type species and is further divided into six subspecies that include over 2,650 serotypes. Salmonella was named after Daniel Elmer Salmon (1850–1914), an American veterinary surgeon.
Salmonella species are non-spore-forming, predominantly motile enterobacteria with cell diameters between about 0.7 and 1.5 μm, lengths from 2 to 5 μm, and peritrichous flagella (all around the cell body, allowing them to move). They are chemotrophs, obtaining their energy from oxidation and reduction reactions, using organic sources. They are also facultative anaerobes, capable of generating adenosine triphosphate with oxygen ("aerobically") when it is available, or using other electron acceptors or fermentation ("anaerobically") when oxygen is not available.
Salmonella species are intracellular pathogens, of which certain serotypes cause illness such as salmonellosis. Most infections are due to the ingestion of food contaminated by feces. Typhoidal Salmonella serotypes can only be transferred between humans and can cause foodborne illness as well as typhoid and paratyphoid fever. Typhoid fever is caused by typhoidal Salmonella invading the bloodstream, as well as spreading throughout the body, invading organs, and secreting endotoxins (the septic form). This can lead to life-threatening hypovolemic shock and septic shock, and requires intensive care, including antibiotics.
Nontyphoidal Salmonella serotypes are zoonotic and can be transferred from animals and between humans. They usually invade only the gastrointestinal tract and cause salmonellosis, the symptoms of which can be resolved without antibiotics. However, in sub-Saharan Africa, nontyphoidal Salmonella can be invasive and cause paratyphoid fever, which requires immediate antibiotic treatment.
Taxonomy | Salmonella | Wikipedia | 457 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
The genus Salmonella is part of the family of Enterobacteriaceae. Its taxonomy has been revised and has the potential to confuse. The genus comprises two species, S. bongori and S. enterica, the latter of which is divided into six subspecies: S. e. enterica, S. e. salamae, S. e. arizonae, S. e. diarizonae, S. e. houtenae, and S. e. indica. The taxonomic group contains more than 2500 serotypes (also serovars) defined on the basis of the somatic O (lipopolysaccharide) and flagellar H antigens (the Kauffman–White classification). The full name of a serotype is given as, for example, Salmonella enterica subsp. enterica serotype Typhimurium, but can be abbreviated to Salmonella Typhimurium. Further differentiation of strains to assist clinical and epidemiological investigation may be achieved by antibiotic sensitivity testing and by other molecular biology techniques such as pulsed-field gel electrophoresis, multilocus sequence typing, and, increasingly, whole genome sequencing. Historically, salmonellae have been clinically categorized as invasive (typhoidal) or non-invasive (nontyphoidal salmonellae) based on host preference and disease manifestations in humans.
History
Salmonella was first visualized in 1880 by Karl Eberth in the Peyer's patches and spleens of typhoid patients. Four years later, Georg Theodor Gaffky was able to grow the pathogen in pure culture. A year after that, medical research scientist Theobald Smith discovered what would be later known as Salmonella enterica (var. Choleraesuis). At the time, Smith was working as a research laboratory assistant in the Veterinary Division of the United States Department of Agriculture. The division was under the administration of Daniel Elmer Salmon, a veterinary pathologist. Initially, Salmonella Choleraesuis was thought to be the causative agent of hog cholera, so Salmon and Smith named it "Hog-cholera bacillus". The name Salmonella was not used until 1900, when Joseph Leon Lignières proposed that the pathogen discovered by Salmon's group be called Salmonella in his honor. | Salmonella | Wikipedia | 479 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
In the late 1930s, Australian bacteriologist Nancy Atkinson established a salmonella typing laboratory – one of only three in the world at the time – at the Government of South Australia's Laboratory of Pathology and Bacteriology in Adelaide (later the Institute of Medical and Veterinary Science). It was here that Atkinson described multiple new strains of salmonella, including Salmonella Adelaide, which was isolated in 1943. Atkinson published her work on salmonellas in 1957.
Serotyping
Serotyping is done by mixing cells with antibodies for a particular antigen. It can give some idea about risk. A 2014 study showed that S. Reading is very common among young turkey samples, but it is not a significant contributor to human salmonellosis. Serotyping can assist in identifying the source of contamination by matching serotypes in people with serotypes in the suspected source of infection. Appropriate prophylactic treatment can be identified from the known antibiotic resistance of the serotype.
Newer methods of "serotyping" include xMAP and real-time PCR, two methods based on DNA sequences instead of antibody reactions. These methods can be potentially faster, thanks to advances in sequencing technology. These "molecular serotyping" systems actually perform genotyping of the genes that determine surface antigens.
Detection, culture, and growth conditions
Most subspecies of Salmonella produce hydrogen sulfide, which can readily be detected by growing them on media containing ferrous sulfate, such as is used in the triple sugar iron test. Most isolates exist in two phases, a motile phase and a non-motile phase. Cultures that are nonmotile upon primary culture may be switched to the motile phase using a Craigie tube or ditch plate. RVS broth can be used to enrich for Salmonella species for detection in a clinical sample.
Salmonella can also be detected and subtyped using multiplex or real-time polymerase chain reaction (qPCR) from extracted Salmonella DNA.
Mathematical models of Salmonella growth kinetics have been developed for chicken, pork, tomatoes, and melons. Salmonella reproduce asexually with a cell division interval of 40 minutes. | Salmonella | Wikipedia | 448 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
Salmonella species lead predominantly host-associated lifestyles, but the bacteria were found to be able to persist in a bathroom setting for weeks following contamination, and are frequently isolated from water sources, which act as bacterial reservoirs and may help to facilitate transmission between hosts. Salmonella is notorious for its ability to survive desiccation and can persist for years in dry environments and foods.
The bacteria are not destroyed by freezing, but UV light and heat accelerate their destruction. They perish after being heated to for 90 min, or to for 12 min, although if inoculated in high fat, high liquid substances like peanut butter, they gain heat resistance and can survive up to for 30 min. To protect against Salmonella infection, heating food to an internal temperature of is recommended.
Salmonella species can be found in the digestive tracts of humans and animals, especially reptiles. Salmonella on the skin of reptiles or amphibians can be passed to people who handle the animals. Food and water can also be contaminated with the bacteria if they come in contact with the feces of infected people or animals.
Nomenclature
Initially, each Salmonella "species" was named according to clinical consideration, for example Salmonella typhi-murium (mouse-typhoid), S. cholerae-suis (pig-cholera). After host specificity was recognized not to exist for many species, new strains received species names according to the location at which the new strain was isolated.
In 1987, Le Minor and Popoff used molecular findings to argue that Salmonella consisted of only one species, S. enterica, turning former "species" names into serotypes. In 1989, Reeves et al. proposed that the serotype V should remain its own species, resurrecting the name S. bongori. The current (by 2005) nomenclature has thus taken shape, with six recognised subspecies under S. enterica: enterica (serotype I), salamae (serotype II), arizonae (IIIa), diarizonae (IIIb), houtenae (IV), and indica (VI). As specialists in infectious disease are not familiar with the new nomenclature, the traditional nomenclature remains common. | Salmonella | Wikipedia | 453 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
The serotype or serovar is a classification of Salmonella based on antigens that the organism presents. The Kauffman–White classification scheme differentiates serological varieties from each other. Serotypes are usually put into subspecies groups after the genus and species, with the serotypes/serovars capitalized, but not italicized: An example is Salmonella enterica serovar Typhimurium. More modern approaches for typing and subtyping Salmonella include DNA-based methods such as pulsed field gel electrophoresis, multiple-loci VNTR analysis, multilocus sequence typing, and multiplex-PCR-based methods.
In 2005, a third species, Salmonella subterranea, was proposed, but according to the World Health Organization, the bacterium reported does not belong in the genus Salmonella. In 2016, S. subterranea was proposed to be assigned to Atlantibacter subterranea, but LPSN rejects it as an invalid publication, as it was made outside of IJSB and IJSEM. GTDB and NCBI agree with the 2016 reassignment.
GTDB RS202 reports that S. arizonae, S. diarizonae, and S. houtenae should be species of their own.
Pathogenicity
Salmonella species are facultative intracellular pathogens. Salmonella can invade different cell types, including epithelial cells, M cells, macrophages, and dendritic cells. As facultative anaerobic organism, Salmonella uses oxygen to make adenosine triphosphate (ATP) in aerobic environments (i.e., when oxygen is available). However, in anaerobic environments (i.e., when oxygen is not available) Salmonella produces ATP by fermentation — that is, by substituting, instead of oxygen, at least one of four electron acceptors at the end of the electron transport chain: sulfate, nitrate, sulfur, or fumarate (all of which are less efficient than oxygen). | Salmonella | Wikipedia | 432 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
Most infections are due to ingestion of food contaminated by animal feces, or by human feces (for example, from the hands of a food-service worker at a commercial eatery). Salmonella serotypes can be divided into two main groups—typhoidal and nontyphoidal. Typhoidal serotypes include Salmonella Typhi and Salmonella Paratyphi A, which are adapted to humans and do not occur in other animals. Nontyphoidal serotypes are more common, and usually cause self-limiting gastrointestinal disease. They can infect a range of animals, and are zoonotic, meaning they can be transferred between humans and other animals.
Salmonella pathogenicity and host interaction has been studied extensively since the 2010s. Most of the important virulent genes of Salmonella are encoded in five pathogenicity islands — the so-called Salmonella pathogenicity islands (SPIs). These are chromosomal encoded and make a significant contribution to bacterial-host interaction. More traits, like plasmids, flagella or biofilm-related proteins, can contribute in the infection. SPIs are regulated by complex and fine-tuned regulatory networks that allow the gene expression only in the presence of the right environmental stresses.
Molecular modeling and active site analysis of SdiA homolog, a putative quorum sensor for Salmonella typhimurium pathogenicity, reveals the specific binding patterns of AHL transcriptional regulators. It is also known that Salmonella plasmid virulence gene spvB enhances bacterial virulence by inhibiting autophagy.
Typhoidal Salmonella | Salmonella | Wikipedia | 343 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
Typhoid fever is caused by Salmonella serotypes which are strictly adapted to humans or higher primates—these include Salmonella Typhi, Paratyphi A, Paratyphi B, and Paratyphi C. In the systemic form of the disease, salmonellae pass through the lymphatic system of the intestine into the blood of the patients (typhoid form) and are carried to various organs (liver, spleen, kidneys) to form secondary foci (septic form). Endotoxins first act on the vascular and nervous apparatus, resulting in increased permeability and decreased tone of the vessels, upset of thermal regulation, and vomiting and diarrhoea. In severe forms of the disease, enough liquid and electrolytes are lost to upset the water-salt metabolism, decrease the circulating blood volume and arterial pressure, and cause hypovolemic shock. Septic shock may also develop. Shock of mixed character (with signs of both hypovolemic and septic shock) is more common in severe salmonellosis. Oliguria and azotemia may develop in severe cases as a result of renal involvement due to hypoxia and toxemia.
Nontyphoidal Salmonella
Non-invasive
Infection with nontyphoidal serotypes of Salmonella generally results in food poisoning. Infection usually occurs when a person ingests foods that contain a high concentration of the bacteria. Infants and young children are much more susceptible to infection, easily achieved by ingesting a small number of bacteria. In infants, infection through inhalation of bacteria-laden dust is possible. | Salmonella | Wikipedia | 340 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
The organisms enter through the digestive tract and must be ingested in large numbers to cause disease in healthy adults. An infection can only begin after living salmonellae (not merely Salmonella-produced toxins) reach the gastrointestinal tract. Some of the microorganisms are killed in the stomach, while the surviving ones enter the small intestine and multiply in tissues. Gastric acidity is responsible for the destruction of the majority of ingested bacteria, but Salmonella has evolved a degree of tolerance to acidic environments that allows a subset of ingested bacteria to survive. Bacterial colonies may also become trapped in mucus produced in the esophagus. By the end of the incubation period, the nearby host cells are poisoned by endotoxins released from the dead salmonellae. The local response to the endotoxins is enteritis and gastrointestinal disorder.
About 2,000 serotypes of nontyphoidal Salmonella are known, which may be responsible for as many as 1.4 million illnesses in the United States each year. People who are at risk for severe illness include infants, elderly, organ-transplant recipients, and the immunocompromised. | Salmonella | Wikipedia | 250 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
Invasive
While in developed countries, nontyphoidal serotypes present mostly as gastrointestinal disease, in sub-Saharan Africa, these serotypes can create a major problem in bloodstream infections, and are the most commonly isolated bacteria from the blood of those presenting with fever. Bloodstream infections caused by nontyphoidal salmonellae in Africa were reported in 2012 to have a case fatality rate of 20–25%. Most cases of invasive nontyphoidal Salmonella infection (iNTS) are caused by Salmonella enterica Typhimurium or Salmonella enterica Enteritidis. A new form of Salmonella Typhimurium (ST313) emerged in the southeast of the African continent 75 years ago, followed by a second wave which came out of central Africa 18 years later. This second wave of iNTS possibly originated in the Congo Basin, and early in the event picked up a gene that made it resistant to the antibiotic chloramphenicol. This created the need to use expensive antimicrobial drugs in areas of Africa that were very poor, making treatment difficult. The increased prevalence of iNTS in sub-Saharan Africa compared to other regions is thought to be due to the large proportion of the African population with some degree of immune suppression or impairment due to the burden of HIV, malaria, and malnutrition, especially in children. The genetic makeup of iNTS is evolving into a more typhoid-like bacterium, able to efficiently spread around the human body. Symptoms are reported to be diverse, including fever, hepatosplenomegaly, and respiratory symptoms, often with an absence of gastrointestinal symptoms. | Salmonella | Wikipedia | 347 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
Epidemiology
Due to being considered sporadic, between 60% and 80% of salmonella infections cases go undiagnosed. In March 2010, data analysis was completed to estimate an incidence rate of 1140 per 100,000 person-years. In the same analysis, 93.8 million cases of gastroenteritis were due to salmonella infections. At the 5th percentile the estimated amount was 61.8 million cases and at the 95th percentile the estimated amount was 131.6 million cases. The estimated number of deaths due to salmonella was approximately 155,000 deaths. In 2014, in countries such as Bulgaria and Portugal, children under 4 were 32 and 82 times more likely, respectively, to have a salmonella infection. Those who are most susceptible to infection are: children, pregnant women, elderly people, and those with deficient immune systems.
Risk factors for Salmonella infections include a variety of foods. Meats such as chicken and pork have the possibility to be contaminated. A variety of vegetables and sprouts may also have salmonella. Lastly, a variety of processed foods such as chicken nuggets and pot pies may also contain this bacteria.
Successful forms of prevention come from existing entities such as the FDA, United States Department of Agriculture, and the Food Safety and Inspection Service. All of these organizations create standards and inspections to ensure public safety in the U.S. For example, the FSIS agency working with the USDA has a Salmonella Action Plan in place. Recently, it received a two-year plan update in February 2016. Their accomplishments and strategies to reduce Salmonella infection are presented in the plans. The Centers for Disease Control and Prevention also provides valuable information on preventative care, such has how to safely handle raw foods, and the correct way to store these products. In the European Union, the European Food Safety Authority created preventative measures through risk management and risk assessment. From 2005 to 2009, the EFSA placed an approach to reduce exposure to Salmonella. Their approach included risk assessment and risk management of poultry, which resulted in a reduction of infection cases by one half. In Latin America an orally administered vaccine for Salmonella in poultry developed by Dr. Sherry Layton has been introduced which prevents the bacteria from contaminating the birds.
A recent Salmonella Typhimurium outbreak has been linked to chocolate produced in Belgium, leading to the country halting Kinder chocolate production. | Salmonella | Wikipedia | 493 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
Global monitoring
In Germany, food-borne infections must be reported. From 1990 to 2016, the number of officially recorded cases decreased from about 200,000 to about 13,000 cases. In the United States, about 1,200,000 cases of Salmonella infection are estimated to occur each year. A World Health Organization study estimated that 21,650,974 cases of typhoid fever occurred in 2000, 216,510 of which resulted in death, along with 5,412,744 cases of paratyphoid fever.
Molecular mechanisms of infection
The mechanisms of infection differ between typhoidal and nontyphoidal serotypes, owing to their different targets in the body and the different symptoms that they cause. Both groups must enter by crossing the barrier created by the intestinal cell wall, but once they have passed this barrier, they use different strategies to cause infection.
Switch to virulence
While travelling to their target tissue in the gastrointestinal tract, Salmonella is exposed to stomach acid, to the detergent-like activity of bile in the intestine, to decreasing oxygen supply, to the competing normal gut flora, and finally to antimicrobial peptides present on the surface of the cells lining the intestinal wall. All of these form stresses that Salmonella can sense and reacts against, and they form virulence factors and as such regulate the switch from their normal growth in the intestine into virulence.
The switch to virulence gives access to a replication niche inside the host (such as humans), and can be summarised into several stages:
Approach, in which they travel towards a host cell via intestinal peristalsis and through active swimming via the flagella, penetrate the mucus barrier, and locate themselves close to the epithelium lining the intestine,
Adhesion, in which they adhere to a host cell using bacterial adhesins and a type III secretion system,
Invasion, in which Salmonella enter the host cell (see variant mechanisms below),
Replication, in which the bacterium may reproduce inside the host cell,
Spread, in which the bacterium can spread to other organs via cells in the blood (if it succeeded in avoiding the immune defence). Alternatively, bacteria can go back towards the intestine, re-seeding the intestinal population.
Re-invasion (a secondary infection, if now at a systemic site) and further replication. | Salmonella | Wikipedia | 497 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
Mechanisms of entry
Nontyphoidal serotypes preferentially enter M cells on the intestinal wall by bacterial-mediated endocytosis, a process associated with intestinal inflammation and diarrhoea. They are also able to disrupt tight junctions between the cells of the intestinal wall, impairing the cells' ability to stop the flow of ions, water, and immune cells into and out of the intestine. The combination of the inflammation caused by bacterial-mediated endocytosis and the disruption of tight junctions is thought to contribute significantly to the induction of diarrhoea.
Salmonellae are also able to breach the intestinal barrier via phagocytosis and trafficking by CD18-positive immune cells, which may be a mechanism key to typhoidal Salmonella infection. This is thought to be a more stealthy way of passing the intestinal barrier, and may, therefore, contribute to the fact that lower numbers of typhoidal Salmonella are required for infection than nontyphoidal Salmonella. Salmonella cells are able to enter macrophages via macropinocytosis. Typhoidal serotypes can use this to achieve dissemination throughout the body via the mononuclear phagocyte system, a network of connective tissue that contains immune cells, and surrounds tissue associated with the immune system throughout the body.
Much of the success of Salmonella in causing infection is attributed to two type III secretion systems (T3SS) which are expressed at different times during the infection. The T3SS-1 enables the injection of bacterial effectors within the host cytosol. These T3SS-1 effectors stimulate the formation of membrane ruffles allowing the uptake of Salmonella by nonphagocytic cells. Salmonella further resides within a membrane-bound compartment called the Salmonella-Containing Vacuole (SCV). The acidification of the SCV leads to the expression of the T3SS-2. The secretion of T3SS-2 effectors by Salmonella is required for its efficient survival in the host cytosol and establishment of systemic disease. In addition, both T3SS are involved in the colonization of the intestine, induction of intestinal inflammatory responses and diarrhea. These systems contain many genes which must work cooperatively to achieve infection. | Salmonella | Wikipedia | 485 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
The AvrA toxin injected by the SPI1 type III secretion system of S. Typhimurium works to inhibit the innate immune system by virtue of its serine/threonine acetyltransferase activity, and requires binding to eukaryotic target cell phytic acid (IP6). This leaves the host more susceptible to infection.
Clinical symptoms
Salmonellosis is known to be able to cause back pain or spondylosis. It can manifest as five clinical patterns: gastrointestinal tract infection, enteric fever, bacteremia, local infection, and the chronic reservoir state. The initial symptoms are nonspecific fever, weakness, and myalgia among others. In the bacteremia state, it can spread to any parts of the body and this induces localized infection or it forms abscesses. The forms of localized Salmonella infections are arthritis, urinary tract infection, infection of the central nervous system, bone infection, soft tissue infection, etc. Infection may remain as the latent form for a long time, and when the function of reticular endothelial cells is deteriorated, it may become activated and consequently, it may secondarily induce spreading infection in the bone several months or several years after acute salmonellosis.
A 2018 Imperial College London study also shows how salmonella disrupt specific arms of the immune system (e.g. 3 of 5 NF-kappaB proteins) using a family of zinc metalloproteinase effectors, leaving others untouched. Salmonella thyroid abscess has also been reported.
Resistance to oxidative burst
A hallmark of Salmonella pathogenesis is the ability of the bacterium to survive and proliferate within phagocytes. Phagocytes produce DNA-damaging agents such as nitric oxide and oxygen radicals as a defense against pathogens. Thus, Salmonella species must face attack by molecules that challenge genome integrity. Buchmeier et al. showed that mutants of S. enterica lacking RecA or RecBC protein function are highly sensitive to oxidative compounds synthesized by macrophages, and furthermore these findings indicate that successful systemic infection by S. enterica requires RecA- and RecBC-mediated recombinational repair of DNA damage. | Salmonella | Wikipedia | 464 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
Host adaptation
S. enterica, through some of its serotypes such as Typhimurium and Enteritidis, shows signs that it has the ability to infect several different mammalian host species, while other serotypes, such as Typhi, seem to be restricted to only a few hosts. Two ways that Salmonella serotypes have adapted to their hosts are by the loss of genetic material, and mutation. In more complex mammalian species, immune systems, which include pathogen specific immune responses, target serovars of Salmonella by binding antibodies to structures such as flagella. Thus Salmonella that has lost the genetic material which codes for a flagellum to form can evade a host's immune system. mgtC leader RNA from bacteria virulence gene (mgtCBR operon) decreases flagellin production during infection by directly base pairing with mRNAs of the fljB gene encoding flagellin and promotes degradation. In the study by Kisela et al., more pathogenic serovars of S. enterica were found to have certain adhesins in common that have developed out of convergent evolution. This means that, as these strains of Salmonella have been exposed to similar conditions such as immune systems, similar structures evolved separately to negate these similar, more advanced defenses in hosts. Although many questions remain about how Salmonella has evolved into so many different types, Salmonella may have evolved through several phases. For example, as Baumler et al. have suggested, Salmonella most likely evolved through horizontal gene transfer, and through the formation of new serovars due to additional pathogenicity islands, and through an approximation of its ancestry. So, Salmonella could have evolved into its many different serotypes by gaining genetic information from different pathogenic bacteria. The presence of several pathogenicity islands in the genome of different serotypes has lent credence to this theory. | Salmonella | Wikipedia | 391 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
Salmonella sv. Newport shows signs of adaptation to a plant-colonization lifestyle, which may play a role in its disproportionate association with food-borne illness linked to produce. A variety of functions selected for during sv. Newport persistence in tomatoes have been reported to be similar to those selected for in sv. Typhimurium from animal hosts. The papA gene, which is unique to sv. Newport, contributes to the strain's fitness in tomatoes, and has homologs in the genomes of other Enterobacteriaceae that are able to colonize plant and animal hosts.
Research
In addition to their importance as pathogens, nontyphoidal Salmonella species such as S. enterica serovar Typhimurium are commonly used as homologues of typhoid species. Many findings are transferable and it attenuates the danger for the researcher in case of contamination, but is also limited. For example, it is not possible to study specific typhoidal toxins using this model. However, strong research tools such as the commonly-used mouse intestine gastroenteritis model build upon the use of Salmonella Typhimurium.
For genetics, S. Typhimurium has been instrumental in the development of genetic tools that led to an understanding of fundamental bacterial physiology. These developments were enabled by the discovery of the first generalized transducing phage P22 in S. Typhimurium, that allowed quick and easy genetic editing. In turn, this made fine structure genetic analysis possible. The large number of mutants led to a revision of genetic nomenclature for bacteria. Many of the uses of transposons as genetic tools, including transposon delivery, mutagenesis, and construction of chromosome rearrangements, were also developed in S. Typhimurium. These genetic tools also led to a simple test for carcinogens, the Ames test.
As a natural alternative to traditional antimicrobials, phages are being recognised as highly effective control agents for Salmonella and other foodborne bacteria. | Salmonella | Wikipedia | 424 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
Ancient DNA
S. enterica genomes have been reconstructed from up to 6,500 year old human remains across Western Eurasia, which provides evidence for geographic widespread infections with systemic S. enterica during prehistory, and a possible role of the Neolithization process in the evolution of host adaptation. Additional reconstructed genomes from colonial Mexico suggest S. enterica as the cause of cocoliztli, an epidemic in 16th-century New Spain. | Salmonella | Wikipedia | 93 | 42114 | https://en.wikipedia.org/wiki/Salmonella | Biology and health sciences | Other organisms | null |
A server is a computer that provides information to other computers called "clients" on a computer network. This architecture is called the client–server model. Servers can provide various functionalities, often called "services", such as sharing data or resources among multiple clients or performing computations for a client. A single server can serve multiple clients, and a single client can use multiple servers. A client process may run on the same device or may connect over a network to a server on a different device. Typical servers are database servers, file servers, mail servers, print servers, web servers, game servers, and application servers.
Client–server systems are usually most frequently implemented by (and often identified with) the request–response model: a client sends a request to the server, which performs some action and sends a response back to the client, typically with a result or acknowledgment. Designating a computer as "server-class hardware" implies that it is specialized for running servers on it. This often implies that it is more powerful and reliable than standard personal computers, but alternatively, large computing clusters may be composed of many relatively simple, replaceable server components.
History
The use of the word server in computing comes from queueing theory, where it dates to the mid 20th century, being notably used in (along with "service"), the paper that introduced Kendall's notation. In earlier papers, such as the , more concrete terms such as "[telephone] operators" are used.
In computing, "server" dates at least to RFC 5 (1969), one of the earliest documents describing ARPANET (the predecessor of Internet), and is contrasted with "user", distinguishing two types of host: "server-host" and "user-host". The use of "serving" also dates to early documents, such as RFC 4, contrasting "serving-host" with "using-host".
The Jargon File defines server in the common sense of a process performing service for requests, usually remote, with the 1981 version reading:
The average utilization of a server in the early 2000s was 5 to 15%, but with the adoption of virtualization this figure started to increase to reduce the number of servers needed.
Operation | Server (computing) | Wikipedia | 456 | 42116 | https://en.wikipedia.org/wiki/Server%20%28computing%29 | Technology | Networks | null |
Strictly speaking, the term server refers to a computer program or process (running program). Through metonymy, it refers to a device used for (or a device dedicated to) running one or several server programs. On a network, such a device is called a host. In addition to server, the words serve and service (as verb and as noun respectively) are frequently used, though servicer and servant are not. The word service (noun) may refer to the abstract form of functionality, e.g. Web service. Alternatively, it may refer to a computer program that turns a computer into a server, e.g. Windows service. Originally used as "servers serve users" (and "users use servers"), in the sense of "obey", today one often says that "servers serve data", in the same sense as "give". For instance, web servers "serve [up] web pages to users" or "service their requests".
The server is part of the client–server model; in this model, a server serves data for clients. The nature of communication between a client and server is request and response. This is in contrast with peer-to-peer model in which the relationship is on-demand reciprocation. In principle, any computerized process that can be used or called by another process (particularly remotely, particularly to share a resource) is a server, and the calling process or processes is a client. Thus any general-purpose computer connected to a network can host servers. For example, if files on a device are shared by some process, that process is a file server. Similarly, web server software can run on any capable computer, and so a laptop or a personal computer can host a web server.
While request–response is the most common client-server design, there are others, such as the publish–subscribe pattern. In the publish-subscribe pattern, clients register with a pub-sub server, subscribing to specified types of messages; this initial registration may be done by request-response. Thereafter, the pub-sub server forwards matching messages to the clients without any further requests: the server pushes messages to the client, rather than the client pulling messages from the server as in request-response.
Purpose | Server (computing) | Wikipedia | 466 | 42116 | https://en.wikipedia.org/wiki/Server%20%28computing%29 | Technology | Networks | null |
The role of a server is to share data as well as to share resources and distribute work. A server computer can serve its own computer programs as well; depending on the scenario, this could be part of a quid pro quo transaction, or simply a technical possibility. The following table shows several scenarios in which a server is used.
Almost the entire structure of the Internet is based upon a client–server model. High-level root nameservers, DNS, and routers direct the traffic on the internet. There are millions of servers connected to the Internet, running continuously throughout the world and virtually every action taken by an ordinary Internet user requires one or more interactions with one or more servers. There are exceptions that do not use dedicated servers; for example, peer-to-peer file sharing and some implementations of telephony (e.g. pre-Microsoft Skype).
Hardware
Hardware requirement for servers vary widely, depending on the server's purpose and its software. Servers often are more powerful and expensive than the clients that connect to them.
The name server is used both for the hardware and software pieces. For the hardware servers, it is usually limited to mean the high-end machines although software servers can run on a variety of hardwares.
Since servers are usually accessed over a network, many run unattended without a computer monitor or input device, audio hardware and USB interfaces. Many servers do not have a graphical user interface (GUI). They are configured and managed remotely. Remote management can be conducted via various methods including Microsoft Management Console (MMC), PowerShell, SSH and browser-based out-of-band management systems such as Dell's iDRAC or HP's iLo. | Server (computing) | Wikipedia | 349 | 42116 | https://en.wikipedia.org/wiki/Server%20%28computing%29 | Technology | Networks | null |
Large servers
Large traditional single servers would need to be run for long periods without interruption. Availability would have to be very high, making hardware reliability and durability extremely important. Mission-critical enterprise servers would be very fault tolerant and use specialized hardware with low failure rates in order to maximize uptime. Uninterruptible power supplies might be incorporated to guard against power failure. Servers typically include hardware redundancy such as dual power supplies, RAID disk systems, and ECC memory, along with extensive pre-boot memory testing and verification. Critical components might be hot swappable, allowing technicians to replace them on the running server without shutting it down, and to guard against overheating, servers might have more powerful fans or use water cooling. They will often be able to be configured, powered up and down, or rebooted remotely, using out-of-band management, typically based on IPMI. Server casings are usually flat and wide, and designed to be rack-mounted, either on 19-inch racks or on Open Racks.
These types of servers are often housed in dedicated data centers. These will normally have very stable power and Internet and increased security. Noise is also less of a concern, but power consumption and heat output can be a serious issue. Server rooms are equipped with air conditioning devices.
Clusters
A server farm or server cluster is a collection of computer servers maintained by an organization to supply server functionality far beyond the capability of a single device. Modern data centers are now often built of very large clusters of much simpler servers, and there is a collaborative effort, Open Compute Project around this concept.
Appliances
A class of small specialist servers called network appliances are generally at the low end of the scale, often being smaller than common desktop computers. | Server (computing) | Wikipedia | 356 | 42116 | https://en.wikipedia.org/wiki/Server%20%28computing%29 | Technology | Networks | null |
Mobile
A mobile server has a portable form factor, e.g. a laptop. In contrast to large data centers or rack servers, the mobile server is designed for on-the-road or ad hoc deployment into emergency, disaster or temporary environments where traditional servers are not feasible due to their power requirements, size, and deployment time. The main beneficiaries of so-called "server on the go" technology include network managers, software or database developers, training centers, military personnel, law enforcement, forensics, emergency relief groups, and service organizations. To facilitate portability, features such as the keyboard, display, battery (uninterruptible power supply, to provide power redundancy in case of failure), and mouse are all integrated into the chassis.
Operating systems
On the Internet, the dominant operating systems among servers are UNIX-like open-source distributions, such as those based on Linux and FreeBSD, with Windows Server also having a significant share. Proprietary operating systems such as z/OS and macOS Server are also deployed, but in much smaller numbers. Servers that run Linux are commonly used as Webservers or Databanks. Windows Servers are used for Networks that are made out of Windows Clients.
Specialist server-oriented operating systems have traditionally had features such as:
GUI not available or optional
Ability to reconfigure and update both hardware and software to some extent without restart
Advanced backup facilities to permit regular and frequent online backups of critical data,
Transparent data transfer between different volumes or devices
Flexible and advanced networking capabilities
Automation capabilities such as daemons in UNIX and services in Windows
Tight system security, with advanced user, resource, data, and memory protection.
Advanced detection and alerting on conditions such as overheating, processor and disk failure.
In practice, today many desktop and server operating systems share similar code bases, differing mostly in configuration.
Energy consumption
In 2010, data centers (servers, cooling, and other electrical infrastructure) were responsible for 1.1–1.5% of electrical energy consumption worldwide and 1.7–2.2% in the United States. One estimate is that total energy consumption for information and communications technology saves more than 5 times its carbon footprint in the rest of the economy by increasing efficiency.
Global energy consumption is increasing due to the increasing demand of data and bandwidth. Natural Resources Defense Council (NRDC) states that data centers used 91 billion kilowatt hours (kWh) electrical energy in 2013 which accounts to 3% of global electricity usage. | Server (computing) | Wikipedia | 510 | 42116 | https://en.wikipedia.org/wiki/Server%20%28computing%29 | Technology | Networks | null |
Environmental groups have placed focus on the carbon emissions of data centers as it accounts to 200 million metric tons of carbon dioxide in a year. | Server (computing) | Wikipedia | 27 | 42116 | https://en.wikipedia.org/wiki/Server%20%28computing%29 | Technology | Networks | null |
A garden is a planned space, usually outdoors, set aside for the cultivation, display, and enjoyment of plants and other forms of nature. The single feature identifying even the wildest wild garden is control. The garden can incorporate both natural and artificial materials.
Gardens often have design features including statuary, follies, pergolas, trellises, stumperies, dry creek beds, and water features such as fountains, ponds (with or without fish), waterfalls or creeks. Some gardens are for ornamental purposes only, while others also produce food crops, sometimes in separate areas, or sometimes intermixed with the ornamental plants. Food-producing gardens are distinguished from farms by their smaller scale, more labor-intensive methods, and their purpose (enjoyment of a hobby or self-sustenance rather than producing for sale, as in a market garden). Flower gardens combine plants of different heights, colors, textures, and fragrances to create interest and delight the senses.
The most common form today is a residential or public garden, but the term garden has traditionally been a more general one. Zoos, which display wild animals in simulated natural habitats, were formerly called zoological gardens. Western gardens are almost universally based on plants, with garden, which etymologically implies enclosure, often signifying a shortened form of botanical garden. Some traditional types of eastern gardens, such as Zen gardens, however, use plants sparsely or not at all. Landscape gardens, on the other hand, such as the English landscape gardens first developed in the 18th century, may omit flowers altogether.
Landscape architecture is a related professional activity with landscape architects tending to engage in design at many scales and working on both public and private projects.
Etymology
The etymology of the word gardening refers to enclosure: it is from Middle English gardin, from Anglo-French gardin, jardin, of Germanic origin; akin to Old High German gard, gart, an enclosure or compound, as in Stuttgart. See Grad (Slavic settlement) for more complete etymology. The words yard, court, and Latin hortus (meaning "garden", hence horticulture and orchard), are cognates—all referring to an enclosed space.
The term "garden" in British English refers to a small enclosed area of land, usually adjoining a building. This would be referred to as a yard in American English.
Uses | Garden | Wikipedia | 484 | 42139 | https://en.wikipedia.org/wiki/Garden | Technology | Food and health | null |
A garden can have aesthetic, functional, and recreational uses:
Cooperation with nature
Plant cultivation
Garden-based learning
Observation of nature
Bird- and insect-watching
Reflection on the changing seasons
Relaxation
Placing down different types of garden gnomes
Family dinners on the terrace
Children playing in the garden
Reading and relaxing in a hammock
Maintaining the flowerbeds
Pottering in the shed
Basking in warm sunshine
Escaping oppressive sunlight and heat
Growing useful produce
Flowers to cut and bring inside for indoor beauty
Fresh herbs and vegetables for cooking
History
Asia
China
The earliest recorded Chinese gardens were created in the valley of the Yellow River, during the Shang dynasty (1600–1046 BC). These gardens were large enclosed parks where the kings and nobles hunted game, or where fruit and vegetables were grown. Early inscriptions from this period, carved on tortoise shells, have three Chinese characters for garden, you, pu and yuan. You was a royal garden where birds and animals were kept, while pu was a garden for plants. During the Qin dynasty (221–206 BC), yuan became the character for all gardens. The old character for yuan is a small picture of a garden; it is enclosed in a square which can represent a wall, and has symbols which can represent the plan of a structure, a small square which can represent a pond, and a symbol for a plantation or a pomegranate tree.
A famous royal garden of the late Shang dynasty was the Terrace, Pond and Park of the Spirit (Lingtai, Lingzhao Lingyou) built by King Wenwang west of his capital city, Yin. The park was described in the Classic of Poetry this way:
The King makes his promenade in the Park of the Spirit,
The deer are kneeling on the grass, feeding their fawns,
The deer are beautiful and resplendent.
The immaculate cranes have plumes of a brilliant white.
The King makes his promenade to the Pond of the Spirit,
The water is full of fish, who wriggle. | Garden | Wikipedia | 402 | 42139 | https://en.wikipedia.org/wiki/Garden | Technology | Food and health | null |
Another early royal garden was Shaqui, or the Dunes of Sand, built by the last Shang ruler, King Zhou (1075–1046 BC). It was composed of an earth terrace, or tai, which served as an observation platform in the center of a large square park. It was described in one of the early classics of Chinese literature, the Records of the Grand Historian (Shiji). According to the Shiji, one of the most famous features of this garden was the Wine Pool and Meat Forest (酒池肉林). A large pool, big enough for several small boats, was constructed on the palace grounds, with inner linings of polished oval shaped stones from the seashore. The pool was then filled with wine. A small island was constructed in the middle of the pool, where trees were planted, which had skewers of roasted meat hanging from their branches. King Zhou and his friends and concubines drifted in their boats, drinking the wine with their hands and eating the roasted meat from the trees. Later Chinese philosophers and historians cited this garden as an example of decadence and bad taste.
During the Spring and Autumn period (722–481 BC), in 535 BC, the Terrace of Shanghua, with lavishly decorated palaces, was built by King Jing of the Zhou dynasty. In 505 BC, an even more elaborate garden, the Terrace of Gusu, was begun. It was located on the side of a mountain, and included a series of terraces connected by galleries, along with a lake where boats in the form of blue dragons navigated. From the highest terrace, a view extended as far as Lake Tai, the Great Lake.
India
Manasollasa is a twelfth century Sanskrit text that offers details on garden design and a variety of other subjects. Both public parks and woodland gardens are described, with about 40 types of trees recommended for the park in the Vana-krida chapter. Shilparatna, a text from the sixteenth century, states that flower gardens or public parks should be located in the northern portion of a town.
Japan | Garden | Wikipedia | 427 | 42139 | https://en.wikipedia.org/wiki/Garden | Technology | Food and health | null |
The earliest recorded Japanese gardens were the pleasure gardens of the Emperors and nobles. They were mentioned in several brief passages of the , the first chronicle of Japanese history, published in 720 CE. In spring 74 CE, the chronicle recorded: "The Emperor Keikō put a few carp into a pond, and rejoiced to see them morning and evening". The following year, "The Emperor launched a double-hulled boat in the pond of Ijishi at Ihare, and went aboard with his imperial concubine, and they feasted sumptuously together". In 486, the chronicle recorded that "The Emperor Kenzō went into the garden and feasted at the edge of a winding stream".
Korea
Korean gardens are a type of garden described as being natural, informal, simple and unforced, seeking to merge with the natural world. They have a history that goes back more than two thousand years, but are little known in the west. The oldest records date to the Three Kingdoms period (57 BC – 668 AD) when architecture and palace gardens showed a development noted in the Korean History of the Three Kingdoms.
Europe
Gardening was not recognized as an art form in Europe until the mid 16th century when it entered the political discourse, as a symbol of the concept of the "ideal republic". Evoking utopian imagery of the Garden of Eden, a time of abundance and plenty where humans didn't know hunger or the conflicts that arose from property disputes. John Evelyn wrote in the early 17th century, "there is not a more laborious life then is that of a good Gard'ners; but a labour full of tranquility and satisfaction; Natural and Instructive, and such as (if any) contributes to Piety and Contemplation." During the era of Enclosures, the agrarian collectivism of the feudal age was idealized in literary "fantasies of liberating regression to garden and wilderness". | Garden | Wikipedia | 400 | 42139 | https://en.wikipedia.org/wiki/Garden | Technology | Food and health | null |
France
Following his campaign in Italy in 1495, where he saw the gardens and castles of Naples, King Charles VIII brought Italian craftsmen and garden designers, such as Pacello da Mercogliano, from Naples and ordered the construction of Italian-style gardens at his residence at the Château d'Amboise and at Château Gaillard, another private résidence in Amboise. His successor Henry II, who had also travelled to Italy and had met Leonardo da Vinci, created an Italian garden nearby at the Château de Blois. Beginning in 1528, King Francis I created new gardens at the Château de Fontainebleau, which featured fountains, parterres, a forest of pine trees brought from Provence, and the first artificial grotto in France. The Château de Chenonceau had two gardens in the new style, one created for Diane de Poitiers in 1551, and a second for Catherine de' Medici in 1560. In 1536, the architect Philibert de l'Orme, upon his return from Rome, created the gardens of the Château d'Anet following the Italian rules of proportion. The carefully prepared harmony of Anet, with its parterres and surfaces of water integrated with sections of greenery, became one of the earliest and most influential examples of the classic French garden.
The French formal garden () contrasted with the design principles of the English landscape garden () namely, to "force nature" instead of leaving it undisturbed. Typical French formal gardens had "parterres, geometrical shapes and neatly clipped topiary", in contrast to the English style of garden in which "plants and shrubs seem to grow naturally without artifice." By the mid-17th century axial symmetry had ascended to prominence in the French gardening traditions of Andre Mollet and Jacques Boyceau, from which the latter wrote: "All things, however beautiful they may be chosen, will be defective if they are not ordered and placed in proper symmetry." A good example of the French formal style are the Tuileries gardens in Paris which were originally designed during the reign of King Henry II in the mid-sixteenth century. The gardens were redesigned into the formal French style for the Sun King Louis XIV. The gardens were ordered into symmetrical lines: long rows of elm or chestnut trees, clipped hedgerows, along with parterres, "reflect[ing] the orderly triumph of man's will over nature." | Garden | Wikipedia | 496 | 42139 | https://en.wikipedia.org/wiki/Garden | Technology | Food and health | null |
The French landscape garden was influenced by the English landscape garden and gained prominence in the late eighteenth century.
United Kingdom
Before the Grand Manner era, a few significant gardens were found in Britain which were developed under the influence of the continent. Britain's homegrown domestic gardening traditions were mostly practical in purpose, rather than aesthetic, unlike the grand gardens found mostly on castle grounds, and less commonly in universities. Tudor Gardens emphasized contrast rather than transitions, distinguished by color and illusion. They were not intended as a complement to home or architecture, but conceived as independent spaces, arranged to grow and display flowers and ornamental plants. Gardeners demonstrated their artistry in knot gardens, with complex arrangements most commonly included interwoven box hedges, and less commonly fragrant herbs like rosemary. Sanded paths run between the hedgings of open knots whereas closed knots were filled with single colored flowers. The knot and parterre gardens were always placed on level ground, and elevated areas reserved for terraces from which the intricacy of the gardens could be viewed.
Jacobean gardens were described as "a delightful confusion" by Henry Wotton in 1624. Under the influence of the Italian Renaissance, Caroline gardens began to shed some of the chaos of earlier designs, marking the beginning of a trends towards symmetrical unified designs that took the building architecture into account, and featuring an elevated terrace from which home and garden could be viewed. The only surviving Caroline garden is located at Bolsover Castle in Derbyshire, but is too simple to attract much interest. During the reign of Charles II, many new Baroque style country houses were built; while in England Oliver Cromwell sought to destroy many Tudor, Jacobean and Caroline style gardens.
Design
Garden design is the process of creating plans for the layout and planting of gardens and landscapes. Gardens may be designed by garden owners themselves, or by professionals. Professional garden designers tend to be trained in principles of design and horticulture, and have a knowledge and experience of using plants. Some professional garden designers are also landscape architects, a more formal level of training that usually requires an advanced degree and often an occupational license. | Garden | Wikipedia | 423 | 42139 | https://en.wikipedia.org/wiki/Garden | Technology | Food and health | null |
Elements of garden design include the layout of hard landscape, such as paths, rockeries, walls, water features, sitting areas and decking, as well as the plants themselves, with consideration for their horticultural requirements, their season-to-season appearance, lifespan, growth habit, size, speed of growth, and combinations with other plants and landscape features. Most gardens consist of a mixture of natural and constructed elements, although even very 'natural' gardens are always an inherently artificial creation. Natural elements present in a garden principally comprise flora (such as trees and weeds), fauna (such as arthropods and birds), soil, water, air and light. Constructed elements include not only paths, patios, decking, sculptures, drainage systems, lights and buildings (such as sheds, gazebos, pergolas and follies), but also living constructions such as flower beds, ponds and lawns.
Garden needs of maintenance are also taken into consideration. Including the time or funds available for regular maintenance, (this can affect the choices of plants regarding speed of growth) spreading or self-seeding of the plants (annual or perennial), bloom-time, and many other characteristics. Garden design can be roughly divided into two groups, formal and naturalistic gardens. The most important consideration in any garden design is how the garden will be used, followed closely by the desired stylistic genres, and the way the garden space will connect to the home or other structures in the surrounding areas. All of these considerations are subject to the budget limitations. Budget limitations can be addressed by a simpler garden style with fewer plants and less costly hard landscape materials, seeds rather than sod for lawns, and plants that grow quickly; alternatively, garden owners may choose to create their garden over time, area by area.
Types
Environmental impact | Garden | Wikipedia | 368 | 42139 | https://en.wikipedia.org/wiki/Garden | Technology | Food and health | null |
Gardeners may cause environmental damage by the way they garden, or they may enhance their local environment.
Damage by gardeners can include direct destruction of natural habitats when houses and gardens are created; indirect habitat destruction and damage to provide garden materials such as peat, rock for rock gardens, and by the use of tapwater to irrigate gardens; the death of living beings in the garden itself, such as the killing not only of slugs and snails but also their predators such as hedgehogs and song thrushes by metaldehyde slug killer; the death of living beings outside the garden, such as local species extinction by indiscriminate plant collectors; and climate change caused by greenhouse gases produced by gardening.
Climate change
Gardeners can help to prevent climate change in many ways, including the use of trees, shrubs, ground cover plants and other perennial plants in their gardens, turning garden waste into soil organic matter instead of burning it, keeping soil and compost heaps aerated, avoiding peat, switching from power tools to hand tools or changing their garden design so that power tools are not needed, and using nitrogen-fixing plants instead of nitrogen fertiliser.
Climate change will have many impacts on gardens; some studies suggest most of them will be negative. Gardens also contribute to climate change. Greenhouse gases can be produced by gardeners in many ways. The three main greenhouse gases are carbon dioxide, methane, and nitrous oxide. Gardeners produce carbon dioxide directly by overcultivating soil and destroying soil carbon, by burning garden waste on bonfires, by using power tools which burn fossil fuel or use electricity generated by fossil fuels, and by using peat. Gardeners produce methane by compacting the soil and making it anaerobic, and by allowing their compost heaps to become compacted and anaerobic. Gardeners produce nitrous oxide by applying excess nitrogen fertiliser when plants are not actively growing so that the nitrogen in the fertiliser is converted by soil bacteria to nitrous oxide.
Irrigation
Some gardeners manage their gardens without using any water from outside the garden. Examples in Britain include Ventnor Botanic Garden on the Isle of Wight, and parts of Beth Chatto's garden in Essex, Sticky Wicket garden in Dorset, and the Royal Horticultural Society's gardens at Harlow Carr and Hyde Hall.
Rain gardens absorb rainfall falling onto nearby hard surfaces, rather than sending it into stormwater drains. | Garden | Wikipedia | 495 | 42139 | https://en.wikipedia.org/wiki/Garden | Technology | Food and health | null |
Data communication, including data transmission and data reception, is the transfer of data, transmitted and received over a point-to-point or point-to-multipoint communication channel. Examples of such channels are copper wires, optical fibers, wireless communication using radio spectrum, storage media and computer buses. The data are represented as an electromagnetic signal, such as an electrical voltage, radiowave, microwave, or infrared signal.
Analog transmission is a method of conveying voice, data, image, signal or video information using a continuous signal that varies in amplitude, phase, or some other property in proportion to that of a variable. The messages are either represented by a sequence of pulses by means of a line code (baseband transmission), or by a limited set of continuously varying waveforms (passband transmission), using a digital modulation method. The passband modulation and corresponding demodulation is carried out by modem equipment.
Digital communications, including digital transmission and digital reception, is the transfer of
either a digitized analog signal or a born-digital bitstream. According to the most common definition, both baseband and passband bit-stream components are considered part of a digital signal; an alternative definition considers only the baseband signal as digital, and passband transmission of digital data as a form of digital-to-analog conversion.
Distinction between related subjects
Courses and textbooks in the field of data transmission as well as digital transmission and digital communications have similar content.
Digital transmission or data transmission traditionally belongs to telecommunications and electrical engineering. Basic principles of data transmission may also be covered within the computer science or computer engineering topic of data communications, which also includes computer networking applications and communication protocols, for example routing, switching and inter-process communication. Although the Transmission Control Protocol (TCP) involves transmission, TCP and other transport layer protocols are covered in computer networking but not discussed in a textbook or course about data transmission.
In most textbooks, the term analog transmission only refers to the transmission of an analog message signal (without digitization) by means of an analog signal, either as a non-modulated baseband signal or as a passband signal using an analog modulation method such as AM or FM. It may also include analog-over-analog pulse modulated baseband signals such as pulse-width modulation. In a few books within the computer networking tradition, analog transmission also refers to passband transmission of bit-streams using digital modulation methods such as FSK, PSK and ASK. | Data communication | Wikipedia | 499 | 42168 | https://en.wikipedia.org/wiki/Data%20communication | Technology | Basics_3 | null |
The theoretical aspects of data transmission are covered by information theory and coding theory.
Protocol layers and sub-topics
Courses and textbooks in the field of data transmission typically deal with the following OSI model protocol layers and topics:
Layer 1, the physical layer:
Channel coding including
Digital modulation schemes
Line coding schemes
Forward error correction (FEC) codes
Bit synchronization
Multiplexing
Equalization
Channel models
Layer 2, the data link layer:
Channel access schemes, media access control (MAC)
Packet mode communication and Frame synchronization
Error detection and automatic repeat request (ARQ)
Flow control
Layer 6, the presentation layer:
Source coding (digitization and data compression), and information theory.
Cryptography (may occur at any layer)
It is also common to deal with the cross-layer design of those three layers.
Applications and history
Data (mainly but not exclusively informational) has been sent via non-electronic (e.g. optical, acoustic, mechanical) means since the advent of communication. Analog signal data has been sent electronically since the advent of the telephone. However, the first data electromagnetic transmission applications in modern time were electrical telegraphy (1809) and teletypewriters (1906), which are both digital signals. The fundamental theoretical work in data transmission and information theory by Harry Nyquist, Ralph Hartley, Claude Shannon and others during the early 20th century, was done with these applications in mind.
In the early 1960s, Paul Baran invented distributed adaptive message block switching for digital communication of voice messages using switches that were low-cost electronics. Donald Davies invented and implemented modern data communication during 1965-7, including packet switching, high-speed routers, communication protocols, hierarchical computer networks and the essence of the end-to-end principle. Baran's work did not include routers with software switches and communication protocols, nor the idea that users, rather than the network itself, would provide the reliability. Both were seminal contributions that influenced the development of computer networks. | Data communication | Wikipedia | 401 | 42168 | https://en.wikipedia.org/wiki/Data%20communication | Technology | Basics_3 | null |
Data transmission is utilized in computers in computer buses and for communication with peripheral equipment via parallel ports and serial ports such as RS-232 (1969), FireWire (1995) and USB (1996). The principles of data transmission are also utilized in storage media for error detection and correction since 1951. The first practical method to overcome the problem of receiving data accurately by the receiver using digital code was the Barker code invented by Ronald Hugh Barker in 1952 and published in 1953. Data transmission is utilized in computer networking equipment such as modems (1940), local area network (LAN) adapters (1964), repeaters, repeater hubs, microwave links, wireless network access points (1997), etc.
In telephone networks, digital communication is utilized for transferring many phone calls over the same copper cable or fiber cable by means of pulse-code modulation (PCM) in combination with time-division multiplexing (TDM) (1962). Telephone exchanges have become digital and software controlled, facilitating many value-added services. For example, the first AXE telephone exchange was presented in 1976. Digital communication to the end user using Integrated Services Digital Network (ISDN) services became available in the late 1980s. Since the end of the 1990s, broadband access techniques such as ADSL, Cable modems, fiber-to-the-building (FTTB) and fiber-to-the-home (FTTH) have become widespread to small offices and homes. The current tendency is to replace traditional telecommunication services with packet mode communication such as IP telephony and IPTV.
Transmitting analog signals digitally allows for greater signal processing capability. The ability to process a communications signal means that errors caused by random processes can be detected and corrected. Digital signals can also be sampled instead of continuously monitored. The multiplexing of multiple digital signals is much simpler compared to the multiplexing of analog signals. Because of all these advantages, because of the vast demand to transmit computer data and the ability of digital communications to do so and because recent advances in wideband communication channels and solid-state electronics have allowed engineers to realize these advantages fully, digital communications have grown quickly.
The digital revolution has also resulted in many digital telecommunication applications where the principles of data transmission are applied. Examples include second-generation (1991) and later cellular telephony, video conferencing, digital TV (1998), digital radio (1999), and telemetry. | Data communication | Wikipedia | 491 | 42168 | https://en.wikipedia.org/wiki/Data%20communication | Technology | Basics_3 | null |
Data transmission, digital transmission or digital communications is the transfer of data over a point-to-point or point-to-multipoint communication channel. Examples of such channels include copper wires, optical fibers, wireless communication channels, storage media and computer buses. The data are represented as an electromagnetic signal, such as an electrical voltage, radio wave, microwave, or infrared light.
While analog transmission is the transfer of a continuously varying analog signal over an analog channel, digital communication is the transfer of discrete messages over a digital or an analog channel. The messages are either represented by a sequence of pulses by means of a line code (baseband transmission), or by a limited set of continuously varying wave forms (passband transmission), using a digital modulation method. The passband modulation and corresponding demodulation (also known as detection) is carried out by modem equipment. According to the most common definition of a digital signal, both baseband and passband signals representing bit-streams are considered as digital transmission, while an alternative definition only considers the baseband signal as digital, and passband transmission of digital data as a form of digital-to-analog conversion.
Data transmitted may be digital messages originating from a data source, for example a computer or a keyboard. It may also be an analog signal such as a phone call or a video signal, digitized into a bit-stream for example using pulse-code modulation (PCM) or more advanced source coding (analog-to-digital conversion and data compression) schemes. This source coding and decoding is carried out by codec equipment.
Serial and parallel transmission
In telecommunications, serial transmission is the sequential transmission of signal elements of a group representing a character or other entity of data. Digital serial transmissions are bits sent over a single wire, frequency or optical path sequentially. Because it requires less signal processing and less chances for error than parallel transmission, the transfer rate of each individual path may be faster. This can be used over longer distances and a check digit or parity bit can be sent along with the data easily. | Data communication | Wikipedia | 417 | 42168 | https://en.wikipedia.org/wiki/Data%20communication | Technology | Basics_3 | null |
Parallel transmission is the simultaneous transmission of related signal elements over two or more separate paths. Multiple electrical wires are used that can transmit multiple bits simultaneously, which allows for higher data transfer rates than can be achieved with serial transmission. This method is typically used internally within the computer, for example, the internal buses, and sometimes externally for such things as printers. Timing skew can be a significant issue in these systems because the wires in parallel data transmission unavoidably have slightly different properties so some bits may arrive before others, which may corrupt the message. This issue tends to worsen with distance making parallel data transmission less reliable for long distances.
Communication channels
Some communications channel types include:
Data transmission circuit
Full-duplex
Half-duplex
Simplex
Multi-drop:
Bus network
Mesh network
Ring network
Star network
Wireless network
Point-to-point
Asynchronous and synchronous data transmission
Asynchronous serial communication uses start and stop bits to signify the beginning and end of transmission. This method of transmission is used when data are sent intermittently as opposed to in a solid stream.
Synchronous transmission synchronizes transmission speeds at both the receiving and sending end of the transmission using clock signals. The clock may be a separate signal or embedded in the data. A continual stream of data is then sent between the two nodes. Due to there being no start and stop bits, the data transfer rate may be more efficient. | Data communication | Wikipedia | 292 | 42168 | https://en.wikipedia.org/wiki/Data%20communication | Technology | Basics_3 | null |
Data mining is the process of extracting and discovering patterns in large data sets involving methods at the intersection of machine learning, statistics, and database systems. Data mining is an interdisciplinary subfield of computer science and statistics with an overall goal of extracting information (with intelligent methods) from a data set and transforming the information into a comprehensible structure for further use. Data mining is the analysis step of the "knowledge discovery in databases" process, or KDD. Aside from the raw analysis step, it also involves database and data management aspects, data pre-processing, model and inference considerations, interestingness metrics, complexity considerations, post-processing of discovered structures, visualization, and online updating.
The term "data mining" is a misnomer because the goal is the extraction of patterns and knowledge from large amounts of data, not the extraction (mining) of data itself. It also is a buzzword and is frequently applied to any form of large-scale data or information processing (collection, extraction, warehousing, analysis, and statistics) as well as any application of computer decision support system, including artificial intelligence (e.g., machine learning) and business intelligence. Often the more general terms (large scale) data analysis and analytics—or, when referring to actual methods, artificial intelligence and machine learning—are more appropriate.
The actual data mining task is the semi-automatic or automatic analysis of large quantities of data to extract previously unknown, interesting patterns such as groups of data records (cluster analysis), unusual records (anomaly detection), and dependencies (association rule mining, sequential pattern mining). This usually involves using database techniques such as spatial indices. These patterns can then be seen as a kind of summary of the input data, and may be used in further analysis or, for example, in machine learning and predictive analytics. For example, the data mining step might identify multiple groups in the data, which can then be used to obtain more accurate prediction results by a decision support system. Neither the data collection, data preparation, nor result interpretation and reporting is part of the data mining step, although they do belong to the overall KDD process as additional steps. | Data mining | Wikipedia | 444 | 42253 | https://en.wikipedia.org/wiki/Data%20mining | Technology | Computer software | null |
The difference between data analysis and data mining is that data analysis is used to test models and hypotheses on the dataset, e.g., analyzing the effectiveness of a marketing campaign, regardless of the amount of data. In contrast, data mining uses machine learning and statistical models to uncover clandestine or hidden patterns in a large volume of data.
The related terms data dredging, data fishing, and data snooping refer to the use of data mining methods to sample parts of a larger population data set that are (or may be) too small for reliable statistical inferences to be made about the validity of any patterns discovered. These methods can, however, be used in creating new hypotheses to test against the larger data populations.
Etymology
In the 1960s, statisticians and economists used terms like data fishing or data dredging to refer to what they considered the bad practice of analyzing data without an a-priori hypothesis. The term "data mining" was used in a similarly critical way by economist Michael Lovell in an article published in the Review of Economic Studies in 1983. Lovell indicates that the practice "masquerades under a variety of aliases, ranging from "experimentation" (positive) to "fishing" or "snooping" (negative).
The term data mining appeared around 1990 in the database community, with generally positive connotations. For a short time in 1980s, the phrase "database mining"™, was used, but since it was trademarked by HNC, a San Diego–based company, to pitch their Database Mining Workstation; researchers consequently turned to data mining. Other terms used include data archaeology, information harvesting, information discovery, knowledge extraction, etc. Gregory Piatetsky-Shapiro coined the term "knowledge discovery in databases" for the first workshop on the same topic (KDD-1989) and this term became more popular in the AI and machine learning communities. However, the term data mining became more popular in the business and press communities. Currently, the terms data mining and knowledge discovery are used interchangeably. | Data mining | Wikipedia | 419 | 42253 | https://en.wikipedia.org/wiki/Data%20mining | Technology | Computer software | null |
Background
The manual extraction of patterns from data has occurred for centuries. Early methods of identifying patterns in data include Bayes' theorem (1700s) and regression analysis (1800s). The proliferation, ubiquity and increasing power of computer technology have dramatically increased data collection, storage, and manipulation ability. As data sets have grown in size and complexity, direct "hands-on" data analysis has increasingly been augmented with indirect, automated data processing, aided by other discoveries in computer science, specially in the field of machine learning, such as neural networks, cluster analysis, genetic algorithms (1950s), decision trees and decision rules (1960s), and support vector machines (1990s). Data mining is the process of applying these methods with the intention of uncovering hidden patterns. in large data sets. It bridges the gap from applied statistics and artificial intelligence (which usually provide the mathematical background) to database management by exploiting the way data is stored and indexed in databases to execute the actual learning and discovery algorithms more efficiently, allowing such methods to be applied to ever-larger data sets.
Process
The knowledge discovery in databases (KDD) process is commonly defined with the stages:
Selection
Pre-processing
Transformation
Data mining
Interpretation/evaluation.
It exists, however, in many variations on this theme, such as the Cross-industry standard process for data mining (CRISP-DM) which defines six phases:
Business understanding
Data understanding
Data preparation
Modeling
Evaluation
Deployment
or a simplified process such as (1) Pre-processing, (2) Data Mining, and (3) Results Validation.
Polls conducted in 2002, 2004, 2007 and 2014 show that the CRISP-DM methodology is the leading methodology used by data miners.
The only other data mining standard named in these polls was SEMMA. However, 3–4 times as many people reported using CRISP-DM. Several teams of researchers have published reviews of data mining process models, and Azevedo and Santos conducted a comparison of CRISP-DM and SEMMA in 2008. | Data mining | Wikipedia | 405 | 42253 | https://en.wikipedia.org/wiki/Data%20mining | Technology | Computer software | null |
Pre-processing
Before data mining algorithms can be used, a target data set must be assembled. As data mining can only uncover patterns actually present in the data, the target data set must be large enough to contain these patterns while remaining concise enough to be mined within an acceptable time limit. A common source for data is a data mart or data warehouse. Pre-processing is essential to analyze the multivariate data sets before data mining. The target set is then cleaned. Data cleaning removes the observations containing noise and those with missing data.
Data mining
Data mining involves six common classes of tasks:
Anomaly detection (outlier/change/deviation detection) – The identification of unusual data records, that might be interesting or data errors that require further investigation due to being out of standard range.
Association rule learning (dependency modeling) – Searches for relationships between variables. For example, a supermarket might gather data on customer purchasing habits. Using association rule learning, the supermarket can determine which products are frequently bought together and use this information for marketing purposes. This is sometimes referred to as market basket analysis.
Clustering – is the task of discovering groups and structures in the data that are in some way or another "similar", without using known structures in the data.
Classification – is the task of generalizing known structure to apply to new data. For example, an e-mail program might attempt to classify an e-mail as "legitimate" or as "spam".
Regression – attempts to find a function that models the data with the least error that is, for estimating the relationships among data or datasets.
Summarization – providing a more compact representation of the data set, including visualization and report generation.
Results validation
Data mining can unintentionally be misused, producing results that appear to be significant but which do not actually predict future behavior and cannot be reproduced on a new sample of data, therefore bearing little use. This is sometimes caused by investigating too many hypotheses and not performing proper statistical hypothesis testing. A simple version of this problem in machine learning is known as overfitting, but the same problem can arise at different phases of the process and thus a train/test split—when applicable at all—may not be sufficient to prevent this from happening. | Data mining | Wikipedia | 460 | 42253 | https://en.wikipedia.org/wiki/Data%20mining | Technology | Computer software | null |
The final step of knowledge discovery from data is to verify that the patterns produced by the data mining algorithms occur in the wider data set. Not all patterns found by the algorithms are necessarily valid. It is common for data mining algorithms to find patterns in the training set which are not present in the general data set. This is called overfitting. To overcome this, the evaluation uses a test set of data on which the data mining algorithm was not trained. The learned patterns are applied to this test set, and the resulting output is compared to the desired output. For example, a data mining algorithm trying to distinguish "spam" from "legitimate" e-mails would be trained on a training set of sample e-mails. Once trained, the learned patterns would be applied to the test set of e-mails on which it had not been trained. The accuracy of the patterns can then be measured from how many e-mails they correctly classify. Several statistical methods may be used to evaluate the algorithm, such as ROC curves.
If the learned patterns do not meet the desired standards, it is necessary to re-evaluate and change the pre-processing and data mining steps. If the learned patterns do meet the desired standards, then the final step is to interpret the learned patterns and turn them into knowledge.
Research
The premier professional body in the field is the Association for Computing Machinery's (ACM) Special Interest Group (SIG) on Knowledge Discovery and Data Mining (SIGKDD). Since 1989, this ACM SIG has hosted an annual international conference and published its proceedings, and since 1999 it has published a biannual academic journal titled "SIGKDD Explorations".
Computer science conferences on data mining include:
CIKM Conference – ACM Conference on Information and Knowledge Management
European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases
KDD Conference – ACM SIGKDD Conference on Knowledge Discovery and Data Mining
Data mining topics are also present in many data management/database conferences such as the ICDE Conference, SIGMOD Conference and International Conference on Very Large Data Bases. | Data mining | Wikipedia | 430 | 42253 | https://en.wikipedia.org/wiki/Data%20mining | Technology | Computer software | null |
Standards
There have been some efforts to define standards for the data mining process, for example, the 1999 European Cross Industry Standard Process for Data Mining (CRISP-DM 1.0) and the 2004 Java Data Mining standard (JDM 1.0). Development on successors to these processes (CRISP-DM 2.0 and JDM 2.0) was active in 2006 but has stalled since. JDM 2.0 was withdrawn without reaching a final draft.
For exchanging the extracted models—in particular for use in predictive analytics—the key standard is the Predictive Model Markup Language (PMML), which is an XML-based language developed by the Data Mining Group (DMG) and supported as exchange format by many data mining applications. As the name suggests, it only covers prediction models, a particular data mining task of high importance to business applications. However, extensions to cover (for example) subspace clustering have been proposed independently of the DMG.
Notable uses
Data mining is used wherever there is digital data available. Notable examples of data mining can be found throughout business, medicine, science, finance, construction, and surveillance.
Privacy concerns and ethics
While the term "data mining" itself may have no ethical implications, it is often associated with the mining of information in relation to user behavior (ethical and otherwise).
The ways in which data mining can be used can in some cases and contexts raise questions regarding privacy, legality, and ethics. In particular, data mining government or commercial data sets for national security or law enforcement purposes, such as in the Total Information Awareness Program or in ADVISE, has raised privacy concerns.
Data mining requires data preparation which uncovers information or patterns which compromise confidentiality and privacy obligations. A common way for this to occur is through data aggregation. Data aggregation involves combining data together (possibly from various sources) in a way that facilitates analysis (but that also might make identification of private, individual-level data deducible or otherwise apparent). This is not data mining per se, but a result of the preparation of data before—and for the purposes of—the analysis. The threat to an individual's privacy comes into play when the data, once compiled, cause the data miner, or anyone who has access to the newly compiled data set, to be able to identify specific individuals, especially when the data were originally anonymous. | Data mining | Wikipedia | 483 | 42253 | https://en.wikipedia.org/wiki/Data%20mining | Technology | Computer software | null |
It is recommended to be aware of the following before data are collected:
The purpose of the data collection and any (known) data mining projects.
How the data will be used.
Who will be able to mine the data and use the data and their derivatives.
The status of security surrounding access to the data.
How collected data can be updated.
Data may also be modified so as to become anonymous, so that individuals may not readily be identified. However, even "anonymized" data sets can potentially contain enough information to allow identification of individuals, as occurred when journalists were able to find several individuals based on a set of search histories that were inadvertently released by AOL.
The inadvertent revelation of personally identifiable information leading to the provider violates Fair Information Practices. This indiscretion can cause financial,
emotional, or bodily harm to the indicated individual. In one instance of privacy violation, the patrons of Walgreens filed a lawsuit against the company in 2011 for selling
prescription information to data mining companies who in turn provided the data
to pharmaceutical companies.
Situation in Europe
Europe has rather strong privacy laws, and efforts are underway to further strengthen the rights of the consumers. However, the U.S.–E.U. Safe Harbor Principles, developed between 1998 and 2000, currently effectively expose European users to privacy exploitation by U.S. companies. As a consequence of Edward Snowden's global surveillance disclosure, there has been increased discussion to revoke this agreement, as in particular the data will be fully exposed to the National Security Agency, and attempts to reach an agreement with the United States have failed.
In the United Kingdom in particular there have been cases of corporations using data mining as a way to target certain groups of customers forcing them to pay unfairly high prices. These groups tend to be people of lower socio-economic status who are not savvy to the ways they can be exploited in digital market places.
Situation in the United States | Data mining | Wikipedia | 394 | 42253 | https://en.wikipedia.org/wiki/Data%20mining | Technology | Computer software | null |
In the United States, privacy concerns have been addressed by the US Congress via the passage of regulatory controls such as the Health Insurance Portability and Accountability Act (HIPAA). The HIPAA requires individuals to give their "informed consent" regarding information they provide and its intended present and future uses. According to an article in Biotech Business Week, "'[i]n practice, HIPAA may not offer any greater protection than the longstanding regulations in the research arena,' says the AAHC. More importantly, the rule's goal of protection through informed consent is approach a level of incomprehensibility to average individuals." This underscores the necessity for data anonymity in data aggregation and mining practices.
U.S. information privacy legislation such as HIPAA and the Family Educational Rights and Privacy Act (FERPA) applies only to the specific areas that each such law addresses. The use of data mining by the majority of businesses in the U.S. is not controlled by any legislation.
Copyright law
Situation in Europe
Under European copyright database laws, the mining of in-copyright works (such as by web mining) without the permission of the copyright owner is not legal. Where a database is pure data in Europe, it may be that there is no copyright—but database rights may exist, so data mining becomes subject to intellectual property owners' rights that are protected by the Database Directive. On the recommendation of the Hargreaves review, this led to the UK government to amend its copyright law in 2014 to allow content mining as a limitation and exception. The UK was the second country in the world to do so after Japan, which introduced an exception in 2009 for data mining. However, due to the restriction of the Information Society Directive (2001), the UK exception only allows content mining for non-commercial purposes. UK copyright law also does not allow this provision to be overridden by contractual terms and conditions.
Since 2020 also Switzerland has been regulating data mining by allowing it in the research field under certain conditions laid down by art. 24d of the Swiss Copyright Act. This new article entered into force on 1 April 2020.
The European Commission facilitated stakeholder discussion on text and data mining in 2013, under the title of Licences for Europe. The focus on the solution to this legal issue, such as licensing rather than limitations and exceptions, led to representatives of universities, researchers, libraries, civil society groups and open access publishers to leave the stakeholder dialogue in May 2013.
Situation in the United States | Data mining | Wikipedia | 510 | 42253 | https://en.wikipedia.org/wiki/Data%20mining | Technology | Computer software | null |
US copyright law, and in particular its provision for fair use, upholds the legality of content mining in America, and other fair use countries such as Israel, Taiwan and South Korea. As content mining is transformative, that is it does not supplant the original work, it is viewed as being lawful under fair use. For example, as part of the Google Book settlement the presiding judge on the case ruled that Google's digitization project of in-copyright books was lawful, in part because of the transformative uses that the digitization project displayed—one being text and data mining.
Software
Free open-source data mining software and applications
The following applications are available under free/open-source licenses. Public access to application source code is also available.
Carrot2: Text and search results clustering framework.
Chemicalize.org: A chemical structure miner and web search engine.
ELKI: A university research project with advanced cluster analysis and outlier detection methods written in the Java language.
GATE: a natural language processing and language engineering tool.
KNIME: The Konstanz Information Miner, a user-friendly and comprehensive data analytics framework.
Massive Online Analysis (MOA): a real-time big data stream mining with concept drift tool in the Java programming language.
MEPX: cross-platform tool for regression and classification problems based on a Genetic Programming variant.
mlpack: a collection of ready-to-use machine learning algorithms written in the C++ language.
NLTK (Natural Language Toolkit): A suite of libraries and programs for symbolic and statistical natural language processing (NLP) for the Python language.
OpenNN: Open neural networks library.
Orange: A component-based data mining and machine learning software suite written in the Python language.
PSPP: Data mining and statistics software under the GNU Project similar to SPSS
R: A programming language and software environment for statistical computing, data mining, and graphics. It is part of the GNU Project.
scikit-learn: An open-source machine learning library for the Python programming language;
Torch: An open-source deep learning library for the Lua programming language and scientific computing framework with wide support for machine learning algorithms.
UIMA: The UIMA (Unstructured Information Management Architecture) is a component framework for analyzing unstructured content such as text, audio and video – originally developed by IBM.
Weka: A suite of machine learning software applications written in the Java programming language. | Data mining | Wikipedia | 502 | 42253 | https://en.wikipedia.org/wiki/Data%20mining | Technology | Computer software | null |
Proprietary data-mining software and applications
The following applications are available under proprietary licenses.
Angoss KnowledgeSTUDIO: data mining tool
LIONsolver: an integrated software application for data mining, business intelligence, and modeling that implements the Learning and Intelligent OptimizatioN (LION) approach.
PolyAnalyst: data and text mining software by Megaputer Intelligence.
Microsoft Analysis Services: data mining software provided by Microsoft.
NetOwl: suite of multilingual text and entity analytics products that enable data mining.
Oracle Data Mining: data mining software by Oracle Corporation.
PSeven: platform for automation of engineering simulation and analysis, multidisciplinary optimization and data mining provided by DATADVANCE.
Qlucore Omics Explorer: data mining software.
RapidMiner: An environment for machine learning and data mining experiments.
SAS Enterprise Miner: data mining software provided by the SAS Institute.
SPSS Modeler: data mining software provided by IBM.
STATISTICA Data Miner: data mining software provided by StatSoft.
Tanagra: Visualisation-oriented data mining software, also for teaching.
Vertica: data mining software provided by Hewlett-Packard.
Google Cloud Platform: automated custom ML models managed by Google.
Amazon SageMaker: managed service provided by Amazon for creating & productionising custom ML models. | Data mining | Wikipedia | 264 | 42253 | https://en.wikipedia.org/wiki/Data%20mining | Technology | Computer software | null |
Irrigation (also referred to as watering of plants) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been developed by many cultures around the world. Irrigation helps to grow crops, maintain landscapes, and revegetate disturbed soils in dry areas and during times of below-average rainfall. In addition to these uses, irrigation is also employed to protect crops from frost, suppress weed growth in grain fields, and prevent soil consolidation. It is also used to cool livestock, reduce dust, dispose of sewage, and support mining operations. Drainage, which involves the removal of surface and sub-surface water from a given location, is often studied in conjunction with irrigation.
There are several methods of irrigation that differ in how water is supplied to plants. Surface irrigation, also known as gravity irrigation, is the oldest form of irrigation and has been in use for thousands of years. In sprinkler irrigation, water is piped to one or more central locations within the field and distributed by overhead high-pressure water devices. Micro-irrigation is a system that distributes water under low pressure through a piped network and applies it as a small discharge to each plant. Micro-irrigation uses less pressure and water flow than sprinkler irrigation. Drip irrigation delivers water directly to the root zone of plants. Subirrigation has been used in field crops in areas with high water tables for many years. It involves artificially raising the water table to moisten the soil below the root zone of plants.
Irrigation water can come from groundwater (extracted from springs or by using wells), from surface water (withdrawn from rivers, lakes or reservoirs) or from non-conventional sources like treated wastewater, desalinated water, drainage water, or fog collection. Irrigation can be supplementary to rainfall, which is common in many parts of the world as rainfed agriculture, or it can be full irrigation, where crops rarely rely on any contribution from rainfall. Full irrigation is less common and only occurs in arid landscapes with very low rainfall or when crops are grown in semi-arid areas outside of rainy seasons. | Irrigation | Wikipedia | 445 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
The environmental effects of irrigation relate to the changes in quantity and quality of soil and water as a result of irrigation and the subsequent effects on natural and social conditions in river basins and downstream of an irrigation scheme. The effects stem from the altered hydrological conditions caused by the installation and operation of the irrigation scheme. Amongst some of these problems is depletion of underground aquifers through overdrafting. Soil can be over-irrigated due to poor distribution uniformity or management wastes water, chemicals, and may lead to water pollution. Over-irrigation can cause deep drainage from rising water tables that can lead to problems of irrigation salinity requiring watertable control by some form of subsurface land drainage.
Extent
In 2000, the total fertile land was 2,788,000 km2 (689 million acres) and it was equipped with irrigation infrastructure worldwide. About 68% of this area is in Asia, 17% in the Americas, 9% in Europe, 5% in Africa and 1% in Oceania. The largest contiguous areas of high irrigation density are found in Northern and Eastern India and Pakistan along the Ganges and Indus rivers; in the Hai He, Huang He and Yangtze basins in China; along the Nile river in Egypt and Sudan; and in the Mississippi-Missouri river basin, the Southern Great Plains, and in parts of California in the United States. Smaller irrigation areas are spread across almost all populated parts of the world.
By 2012, the area of irrigated land had increased to an estimated total of 3,242,917 km2 (801 million acres), which is nearly the size of India. The irrigation of 20% of farming land accounts for the production of 40% of food production.
Global overview
The scale of irrigation increased dramatically over the 20th century. In 1800, 8 million hectares globally were irrigated, in 1950, 94 million hectares, and in 1990, 235 million hectares. By 1990, 30% of the global food production came from irrigated land. Irrigation techniques across the globe includes canals redirecting surface water, groundwater pumping, and diverting water from dams. National governments lead most irrigation schemes within their borders, but private investors and other nations, especially the United States, China, and European countries like the United Kingdom, also fund and organize some schemes within other nations. | Irrigation | Wikipedia | 474 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
By 2021 the global land area equipped for irrigation reached 352 million ha, an increase of 22% from the 289 million ha of 2000 and more than twice the 1960s land area equipped for irrigation. The vast majority is located in Asia (70%), where irrigation was a key component of the green revolution; the Americas account for 16% and Europe for 8% of the world total. India (76 million ha) and China (75 million ha) have the largest equipped area for irrigation, far ahead of the United States o fAmerica (27 million ha). China and India also have the largest net gains in equipped area between 2000 and 2020 (+21 million ha for China and +15 million ha for India). All the regions saw increases in the area equipped for irrigation, with Africa growing the fastest (+29%), followed by Asia (+25%), Oceania (+24%), the Americas (+19%) and Europe (+2%).
Irrigation enables the production of more crops, especially commodity crops in areas which otherwise could not support them. Countries frequently invested in irrigation to increase wheat, rice, or cotton production, often with the overarching goal of increasing self-sufficiency.
Example values for crops
Water sources
Groundwater and surface water
Irrigation water can come from groundwater (extracted from springs or by using wells), from surface water (withdrawn from rivers, lakes or reservoirs) or from non-conventional sources like treated wastewater, desalinated water, drainage water, or fog collection.
While floodwater harvesting belongs to the accepted irrigation methods, rainwater harvesting is usually not considered as a form of irrigation. Rainwater harvesting is the collection of runoff water from roofs or unused land and the concentration of this.
Treated or untreated wastewater
Other sources
Irrigation water can also come from non-conventional sources like treated wastewater, desalinated water, drainage water, or fog collection.
In countries where humid air sweeps through at night, water can be obtained by condensation onto cold surfaces. This is practiced in the vineyards at Lanzarote using stones to condense water. Fog collectors are also made of canvas or foil sheets. Using condensate from air conditioning units as a water source is also becoming more popular in large urban areas. | Irrigation | Wikipedia | 459 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
a Glasgow-based startup has helped a farmer in Scotland to establish edible saltmarsh crops irrigated with sea water. An acre of previously marginal land has been put under cultivation to grow samphire, sea blite, and sea aster; these plants yield a higher profit than potatoes. The land is flood irrigated twice a day to simulate tidal flooding; the water is pumped from the sea using wind power. Additional benefits are soil remediation and carbon sequestration.
Competition for water resources
Until the 1960s, there were fewer than half the number of people on the planet as of 2024. People were not as wealthy as today, consumed fewer calories and ate less meat, so less water was needed to produce their food. They required a third of the volume of water humans presently take from rivers. Today, the competition for water resources is much more intense, because there are now more than seven billion people on the planet, increasing the likelihood of overconsumption of food produced by water-thirsty animal agriculture and intensive farming practices. This creates increasing competition for water from industry, urbanisation and biofuel crops. Farmers will have to strive to increase productivity to meet growing demands for food, while industry and cities find ways to use water more efficiently.
Successful agriculture is dependent upon farmers having sufficient access to water. However, water scarcity is already a critical constraint to farming in many parts of the world.
Irrigation methods
There are several methods of irrigation. They vary in how the water is supplied to the plants. The goal is to apply the water to the plants as uniformly as possible, so that each plant has the amount of water it needs, neither too much nor too little. Irrigation can also be understood whether it is supplementary to rainfall as happens in many parts of the world, or whether it is 'full irrigation' whereby crops rarely depend on any contribution from rainfall. Full irrigation is less common and only happens in arid landscapes experiencing very low rainfall or when crops are grown in semi-arid areas outside of any rainy seasons.
Surface irrigation | Irrigation | Wikipedia | 414 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
Surface irrigation, also known as gravity irrigation, is the oldest form of irrigation and has been in use for thousands of years. In surface (furrow, flood, or level basin) irrigation systems, water moves across the surface of agricultural lands, in order to wet it and infiltrate into the soil. Water moves by following gravity or the slope of the land. Surface irrigation can be subdivided into furrow, border strip or basin irrigation. It is often called flood irrigation when the irrigation results in flooding or near flooding of the cultivated land. Historically, surface irrigation is the most common method of irrigating agricultural land across most parts of the world. The water application efficiency of surface irrigation is typically lower than other forms of irrigation, due in part to the lack of control of applied depths. Surface irrigation involves a significantly lower capital cost and energy requirement than pressurised irrigation systems. Hence it is often the irrigation choice for developing nations, for low value crops and for large fields. Where water levels from the irrigation source permit, the levels are controlled by dikes (levees), usually plugged by soil. This is often seen in terraced rice fields (rice paddies), where the method is used to flood or control the level of water in each distinct field. In some cases, the water is pumped, or lifted by human or animal power to the level of the land.
Surface irrigation is even used to water urban gardens in certain areas, for example, in and around Phoenix, Arizona. The irrigated area is surrounded by a berm and the water is delivered according to a schedule set by a local irrigation district.
A special form of irrigation using surface water is spate irrigation, also called floodwater harvesting. In case of a flood (spate), water is diverted to normally dry river beds (wadis) using a network of dams, gates and channels and spread over large areas. The moisture stored in the soil will be used thereafter to grow crops. Spate irrigation areas are in particular located in semi-arid or arid, mountainous regions.
Micro-irrigation | Irrigation | Wikipedia | 419 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
Micro-irrigation, sometimes called localized irrigation, low volume irrigation, or trickle irrigation is a system where water is distributed under low pressure through a piped network, in a pre-determined pattern, and applied as a small discharge to each plant or adjacent to it. Traditional drip irrigation use individual emitters, subsurface drip irrigation (SDI), micro-spray or micro-sprinklers, and mini-bubbler irrigation all belong to this category of irrigation methods.
Drip irrigation
Drip irrigation, also known as microirrigation or trickle irrigation, functions as its name suggests. In this system, water is delivered at or near the root zone of plants, one drop at a time. This method can be the most water-efficient method of irrigation, if managed properly; evaporation and runoff are minimized. The field water efficiency of drip irrigation is typically in the range of 80 to 90% when managed correctly.
In modern agriculture, drip irrigation is often combined with plastic mulch, further reducing evaporation, and is also the means of delivery of fertilizer. The process is known as fertigation.
Deep percolation, where water moves below the root zone, can occur if a drip system is operated for too long or if the delivery rate is too high. Drip irrigation methods range from very high-tech and computerized to low-tech and labor-intensive. Lower water pressures are usually needed than for most other types of systems, with the exception of low-energy center pivot systems and surface irrigation systems, and the system can be designed for uniformity throughout a field or for precise water delivery to individual plants in a landscape containing a mix of plant species. Although it is difficult to regulate pressure on steep slopes, pressure compensating emitters are available, so the field does not have to be level. High-tech solutions involve precisely calibrated emitters located along lines of tubing that extend from a computerized set of valves.
Sprinkler irrigation | Irrigation | Wikipedia | 406 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
In sprinkler or overhead irrigation, water is piped to one or more central locations within the field and distributed by overhead high-pressure sprinklers or guns. A system using sprinklers, sprays, or guns mounted overhead on permanently installed risers is often referred to as a solid-set irrigation system. Higher pressure sprinklers that rotate are called rotors and are driven by a ball drive, gear drive, or impact mechanism. Rotors can be designed to rotate in a full or partial circle. Guns are similar to rotors, except that they generally operate at very high pressures of 275 to 900 kPa (40 to 130 psi) and flows of 3 to 76 L/s (50 to 1200 US gal/min), usually with nozzle diameters in the range of 10 to 50 mm (0.5 to 1.9 in). Guns are used not only for irrigation, but also for industrial applications such as dust suppression and logging.
Sprinklers can also be mounted on moving platforms connected to the water source by a hose. Automatically moving wheeled systems known as traveling sprinklers may irrigate areas such as small farms, sports fields, parks, pastures, and cemeteries unattended. Most of these use a length of polyethylene tubing wound on a steel drum. As the tubing is wound on the drum powered by the irrigation water or a small gas engine, the sprinkler is pulled across the field. When the sprinkler arrives back at the reel the system shuts off. This type of system is known to most people as a "waterreel" traveling irrigation sprinkler and they are used extensively for dust suppression, irrigation, and land application of waste water.
Other travelers use a flat rubber hose that is dragged along behind while the sprinkler platform is pulled by a cable.
Center pivot
Center pivot irrigation is a form of sprinkler irrigation utilising several segments of pipe (usually galvanized steel or aluminium) joined and supported by trusses, mounted on wheeled towers with sprinklers positioned along its length.
The system moves in a circular pattern and is fed with water from the pivot point at the center of the arc. These systems are found and used in all parts of the world and allow irrigation of all types of terrain. Newer systems have drop sprinkler heads as shown in the image that follows. | Irrigation | Wikipedia | 502 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
most center pivot systems have drops hanging from a U-shaped pipe attached at the top of the pipe with sprinkler heads that are positioned a few feet (at most) above the crop, thus limiting evaporative losses. Drops can also be used with drag hoses or bubblers that deposit the water directly on the ground between crops. Crops are often planted in a circle to conform to the center pivot. This type of system is known as LEPA (Low Energy Precision Application). Originally, most center pivots were water-powered. These were replaced by hydraulic systems (T-L Irrigation) and electric-motor-driven systems (Reinke, Valley, Zimmatic). Many modern pivots feature GPS devices.
Irrigation by lateral move (side roll, wheel line, wheelmove)
A series of pipes, each with a wheel of about 1.5 m diameter permanently affixed to its midpoint, and sprinklers along its length, are coupled together. Water is supplied at one end using a large hose. After sufficient irrigation has been applied to one strip of the field, the hose is removed, the water drained from the system, and the assembly rolled either by hand or with a purpose-built mechanism, so that the sprinklers are moved to a different position across the field. The hose is reconnected. The process is repeated in a pattern until the whole field has been irrigated.
This system is less expensive to install than a center pivot, but much more labor-intensive to operate – it does not travel automatically across the field: it applies water in a stationary strip, must be drained, and then rolled to a new strip. Most systems use 100 or 130 mm (4 or 5 inch) diameter aluminum pipe. The pipe doubles both as water transport and as an axle for rotating all the wheels. A drive system (often found near the centre of the wheel line) rotates the clamped-together pipe sections as a single axle, rolling the whole wheel line. Manual adjustment of individual wheel positions may be necessary if the system becomes misaligned. | Irrigation | Wikipedia | 432 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
Wheel line systems are limited in the amount of water they can carry, and limited in the height of crops that can be irrigated. One useful feature of a lateral move system is that it consists of sections that can be easily disconnected, adapting to field shape as the line is moved. They are most often used for small, rectilinear, or oddly-shaped fields, hilly or mountainous regions, or in regions where labor is inexpensive.
Lawn sprinkler systems
A lawn sprinkler system is permanently installed, as opposed to a hose-end sprinkler, which is portable. Sprinkler systems are installed in residential lawns, in commercial landscapes, for churches and schools, in public parks and cemeteries, and on golf courses. Most of the components of these irrigation systems are hidden under ground, since aesthetics are important in a landscape. A typical lawn sprinkler system will consist of one or more zones, limited in size by the capacity of the water source. Each zone will cover a designated portion of the landscape. Sections of the landscape will usually be divided by microclimate, type of plant material, and type of irrigation equipment. A landscape irrigation system may also include zones containing drip irrigation, bubblers, or other types of equipment besides sprinklers.
Although manual systems are still used, most lawn sprinkler systems may be operated automatically using an irrigation controller, sometimes called a clock or timer. Most automatic systems employ electric solenoid valves. Each zone has one or more of these valves that are wired to the controller. When the controller sends power to the valve, the valve opens, allowing water to flow to the sprinklers in that zone. | Irrigation | Wikipedia | 347 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
There are two main types of sprinklers used in lawn irrigation, pop-up spray heads and rotors. Spray heads have a fixed spray pattern, while rotors have one or more streams that rotate. Spray heads are used to cover smaller areas, while rotors are used for larger areas. Golf course rotors are sometimes so large that a single sprinkler is combined with a valve and called a 'valve in head'. When used in a turf area, the sprinklers are installed with the top of the head flush with the ground surface. When the system is pressurized, the head will pop up out of the ground and water the desired area until the valve closes and shuts off that zone. Once there is no more pressure in the lateral line, the sprinkler head will retract back into the ground. In flower beds or shrub areas, sprinklers may be mounted on above ground risers or even taller pop-up sprinklers may be used and installed flush as in a lawn area.
Hose-end sprinklers
Hose-end sprinklers are devices attached to the end of a garden hose, used for watering lawns, gardens, or plants. They come in a variety of designs and styles, allowing you to adjust the water flow, pattern, and range for efficient irrigation. Some common types of hose-end sprinklers include:
Oscillating Sprinklers: These spray water back and forth in a rectangular or square pattern. They are good for covering large, flat areas evenly.
Impact (or Pulsating) Sprinklers: These create a rotating, pulsating spray, which can cover a circular or semi-circular area. They are useful for watering large lawns.
Stationary Sprinklers: These have a fixed spray pattern and are best for smaller areas or gardens.
Rotary Sprinklers: These use spinning arms to distribute water in a circular or semi-circular pattern.
Traveling Sprinklers: These move along the hose path on their own, watering as they go, ideal for covering long, narrow spaces.
Each type offers different advantages based on garden size and shape, water pressure, and specific watering needs. | Irrigation | Wikipedia | 457 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
Subirrigation
Subirrigation has been used for many years in field crops in areas with high water tables. It is a method of artificially raising the water table to allow the soil to be moistened from below the plants' root zone. Often those systems are located on permanent grasslands in lowlands or river valleys and combined with drainage infrastructure. A system of pumping stations, canals, weirs and gates allows it to increase or decrease the water level in a network of ditches and thereby control the water table.
Subirrigation is also used in the commercial greenhouse production, usually for potted plants. Water is delivered from below, absorbed by upwards, and the excess collected for recycling. Typically, a solution of water and nutrients floods a container or flows through a trough for a short period of time, 10–20 minutes, and is then pumped back into a holding tank for reuse. Sub-irrigation in greenhouses requires fairly sophisticated, expensive equipment and management. Advantages are water and nutrient conservation, and labor savings through reduced system maintenance and automation. It is similar in principle and action to subsurface basin irrigation.
Another type of subirrigation is the self-watering container, also known as a sub-irrigated planter. This consists of a planter suspended over a reservoir with some type of wicking material such as a polyester rope. The water is drawn up the wick through capillary action. A similar technique is the wicking bed; this too uses capillary action.
Efficiency
Modern irrigation methods are efficient enough to supply the entire field uniformly with water, so that each plant has the amount of water it needs, neither too much nor too little. Water use efficiency in the field can be determined as follows:
Field Water Efficiency (%) = (Water Transpired by Crop ÷ Water Applied to Field) x 100 | Irrigation | Wikipedia | 376 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
Increased irrigation efficiency has a number of positive outcomes for the farmer, the community and the wider environment. Low application efficiency infers that the amount of water applied to the field is in excess of the crop or field requirements. Increasing the application efficiency means that the amount of crop produced per unit of water increases. Improved efficiency may either be achieved by applying less water to an existing field or by using water more wisely thereby achieving higher yields in the same area of land. In some parts of the world, farmers are charged for irrigation water hence over-application has a direct financial cost to the farmer. Irrigation often requires pumping energy (either electricity or fossil fuel) to deliver water to the field or supply the correct operating pressure. Hence increased efficiency will reduce both the water cost and energy cost per unit of agricultural production. A reduction of water use on one field may mean that the farmer is able to irrigate a larger area of land, increasing total agricultural production. Low efficiency usually means that excess water is lost through seepage or runoff, both of which can result in loss of crop nutrients or pesticides with potential adverse impacts on the surrounding environment.
Improving the efficiency of irrigation is usually achieved in one of two ways, either by improving the system design or by optimising the irrigation management. Improving system design includes conversion from one form of irrigation to another (e.g. from furrow to drip irrigation) and also through small changes in the current system (for example changing flowrates and operating pressures). Irrigation management refers to the scheduling of irrigation events and decisions around how much water is applied.
Challenges
Environmental impacts
Negative impacts frequently accompany extensive irrigation. Some projects which diverted surface water for irrigation dried up the water sources, which led to a more extreme regional climate. Projects that relied on groundwater and pumped too much from underground aquifers created subsidence and salinization. Salinization of irrigation water in turn damaged the crops and seeped into drinking water. Pests and pathogens also thrived in the irrigation canals or ponds full of still water, which created regional outbreaks of diseases like malaria and schistosomiasis. Governments also used irrigation schemes to encourage migration, especially of more desirable populations into an area. Additionally, some of these large nationwide schemes failed to pay off at all, costing more than any benefit gained from increased crop yields. | Irrigation | Wikipedia | 474 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
Overdrafting (depletion) of underground aquifers: In the mid-20th century, the advent of diesel and electric motors led to systems that could pump groundwater out of major aquifers faster than drainage basins could refill them. This can lead to permanent loss of aquifer capacity, decreased water quality, ground subsidence, and other problems. The future of food production in such areas as the North China Plain, the Punjab region in India and Pakistan, and the Great Plains of the US is threatened by this phenomenon.
Technical challenges
Irrigation schemes involve solving numerous engineering and economic problems while minimizing negative environmental consequences. Such problems include:
Ground subsidence (e.g. New Orleans, Louisiana)
Underirrigation or irrigation giving only just enough water for the plant (e.g. in drip line irrigation) gives poor soil salinity control which leads to increased soil salinity with consequent buildup of toxic salts on soil surface in areas with high evaporation. This requires either leaching to remove these salts and a method of drainage to carry the salts away. When using drip lines, the leaching is best done regularly at certain intervals (with only a slight excess of water), so that the salt is flushed back under the plant's roots.
Overirrigation because of poor distribution uniformity or management wastes water, chemicals, and may lead to water pollution.
Deep drainage (from over-irrigation) may result in rising water tables which in some instances will lead to problems of irrigation salinity requiring watertable control by some form of subsurface land drainage. For example in Australia, over-abstraction of fresh water for intensive irrigation activities has caused 33% of the land area to be at risk of salination.
Drainage front instability, also known as viscous fingering, where an unstable drainage front results in a pattern of fingers and viscous entrapped saturated zones.
Irrigation with saline or high-sodium water may damage soil structure owing to the formation of alkaline soil.
Clogging of filters: algae can clog filters, drip installations, and nozzles. Chlorination, algaecide, UV and ultrasonic methods can be used for algae control in irrigation systems.
Complications in accurately measuring irrigation performance which changes over time and space using measures such as productivity, efficiency, equity and adequacy.
Macro-irrigation, typical in intensive agriculture, where also are used agrochemicals, often causes eutrophication. | Irrigation | Wikipedia | 510 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
Social aspects
Competition for surface water rights and territory defense.
Assisting smallholders in sustainably and collectively managing irrigation technology and changes in technology.
History
Ancient history
Archaeological investigation has found evidence of irrigation in areas lacking sufficient natural rainfall to support crops for rainfed agriculture. Some of the earliest known use of the technology dates to the 6th millennium BCE in Khuzistan in the south-west of Iran. The site of Choga Mami, in present-day Iraq on the border with Iran, is believed to be the earliest to show the first canal irrigation in operation at about 6000 BCE.
Irrigation was used as a means of manipulation of water in the alluvial plains of the Indus valley civilization, the application of which is estimated to have begun around 4500 BCE and drastically increased the size and prosperity of their agricultural settlements. The Indus Valley Civilization developed sophisticated irrigation and water-storage systems, including artificial reservoirs at Girnar dated to 3000 BCE, and an early canal irrigation system from 2600 BCE. Large-scale agriculture was practiced, with an extensive network of canals used for the purpose of irrigation.
Farmers in the Mesopotamian plain used irrigation from at least the third-millennium BCE.
They developed perennial irrigation, regularly watering crops throughout the growing season by coaxing water through a matrix of small channels formed in the field.
Ancient Egyptians practiced basin irrigation using the flooding of the Nile to inundate land plots which had been surrounded by dikes. The flood water remained until the fertile sediment had settled before the engineers returned the surplus to the watercourse. There is evidence of the ancient Egyptian pharaoh Amenemhet III in the twelfth dynasty (about 1800 BCE) using the natural lake of the Faiyum Oasis as a reservoir to store surpluses of water for use during dry seasons. The lake swelled annually from the flooding of the Nile.
The Ancient Nubians developed a form of irrigation by using a waterwheel-like device called a sakia. Irrigation began in Nubia between the third and second millennia BCE. It largely depended upon the flood waters that would flow through the Nile River and other rivers in what is now the Sudan.
In sub-Saharan Africa, irrigation reached the Niger River region cultures and civilizations by the first or second millennium BCE and was based on wet-season flooding and water harvesting. | Irrigation | Wikipedia | 462 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
Evidence of terrace irrigation occurs in pre-Columbian America, early Syria, India, and China. In the Zana Valley of the Andes Mountains in Peru, archaeologists have found remains of three irrigation canals radiocarbon-dated from the 4th millennium BCE, the 3rd millennium BCE and the 9th century CE. These canals provide the earliest record of irrigation in the New World. Traces of a canal possibly dating from the 5th millennium BCE were found under the 4th-millennium canal.
Ancient Persia (modern-day Iran) used irrigation as far back as the 6th millennium BCE to grow barley in areas with insufficient natural rainfall. The Qanats, developed in ancient Persia about 800 BCE, are among the oldest known irrigation methods still in use today. They are now found in Asia, the Middle East, and North Africa. The system comprises a network of vertical wells and gently sloping tunnels driven into the sides of cliffs and steep hills to tap groundwater. The noria, a water wheel with clay pots around the rim powered by the flow of the stream (or by animals where the water source was still), first came into use at about this time among Roman settlers in North Africa. By 150 BCE, the pots were fitted with valves to allow smoother filling as they were forced into the water.
Sri Lanka
The irrigation works of ancient Sri Lanka, the earliest dating from about 300 BCE in the reign of King Pandukabhaya, and under continuous development for the next thousand years, were one of the most complex irrigation systems of the ancient world. In addition to underground canals, the Sinhalese were the first to build completely artificial reservoirs to store water. These reservoirs and canal systems were used primarily to irrigate paddy fields, which require a lot of water to cultivate. Most of these irrigation systems still exist undamaged up to now, in Anuradhapura and Polonnaruwa, because of the advanced and precise engineering. The system was extensively restored and further extended during the reign of King Parakrama Bahu (1153–1186 CE).
China | Irrigation | Wikipedia | 413 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
The oldest known hydraulic engineers of China were Sunshu Ao (6th century BCE) of the Spring and Autumn period and Ximen Bao (5th century BCE) of the Warring States period, both of whom worked on large irrigation projects. In the Sichuan region belonging to the state of Qin of ancient China, the Dujiangyan Irrigation System devised by the Qin Chinese hydrologist and irrigation engineer Li Bing was built in 256 BCE to irrigate a vast area of farmland that today still supplies water. By the 2nd century CE, during the Han dynasty, the Chinese also used chain pumps which lifted water from a lower elevation to a higher one. These were powered by manual foot-pedal, hydraulic waterwheels, or rotating mechanical wheels pulled by oxen. The water was used for public works, providing water for urban residential quarters and palace gardens, but mostly for irrigation of farmland canals and channels in the fields.
Korea
Korea, Jang Yeong-sil, a Korean engineer of the Joseon dynasty, under the active direction of the king, Sejong the Great, invented the world's first rain gauge, uryanggye () in 1441. It was installed in irrigation tanks as part of a nationwide system to measure and collect rainfall for agricultural applications. Planners and farmers could better use the information gathered in the survey with this instrument.
North America | Irrigation | Wikipedia | 271 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
The earliest agricultural irrigation canal system known in the area of the present-day United States dates to between 1200 BCE and 800 BCE and was discovered by Desert Archaeology, Inc. in Marana, Arizona (adjacent to Tucson) in 2009. The irrigation-canal system predates the Hohokam culture by two thousand years and belongs to an unidentified culture. In North America, the Hohokam were the only culture known to rely on irrigation canals to water their crops, and their irrigation systems supported the largest population in the Southwest by CE 1300. The Hohokam constructed various simple canals combined with weirs in their various agricultural pursuits. Between the 7th and 14th centuries, they built and maintained extensive irrigation networks along the lower Salt and middle Gila Rivers that rivaled the complexity of those used in the ancient Near East, Egypt, and China. These were constructed using relatively simple excavation tools, without the benefit of advanced engineering technologies, and achieved drops of a few feet per mile, balancing erosion and siltation. The Hohokam cultivated cotton, tobacco, maize, beans, and squash varieties and harvested an assortment of wild plants. Late in the Hohokam Chronological Sequence, they used extensive dry-farming systems, primarily to grow agave for food and fiber. Their reliance on agricultural strategies based on canal irrigation, vital in their less-than-hospitable desert environment and arid climate, provided the basis for the aggregation of rural populations into stable urban centers.
South America
The oldest known irrigation canals in the Americas are in the desert of northern Peru in the Zaña Valley near the hamlet of Nanchoc. The canals have been radiocarbon dated to at least 3400 BCE and possibly as old as 4700 BCE. The canals at that time irrigated crops such as peanuts, squash, manioc, chenopods, a relative of Quinoa, and later maize. | Irrigation | Wikipedia | 379 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
Modern history
The scale of global irrigation increased dramatically over the 20th century. In 1800, 8 million hectares were irrigated; in 1950, 94 million hectares, and in 1990, 235 million hectares. By 1990, 30% of the global food production came from irrigated land. Irrigation techniques across the globe included canals redirecting surface water, groundwater pumping, and diverting water from dams. National governments led most irrigation schemes within their borders, but private investors and other nations, especially the United States, China, and European countries like the United Kingdom, funded and organized some schemes within other nations. Irrigation enabled the production of more crops, especially commodity crops in areas that otherwise could not support them. Countries frequently invested in irrigation to increase wheat, rice, or cotton production, often with the overarching goal of increasing self-sufficiency. In the 20th century, global anxiety, specifically about the American cotton monopoly, fueled many empirical irrigation projects: Britain began developing irrigation in India, the Ottomans in Egypt, the French in Algeria, the Portuguese in Angola, the Germans in Togo, and Soviets in Central Asia.
Negative impacts frequently accompany extensive irrigation. Some projects that diverted surface water for irrigation dried up the water sources, which led to a more extreme regional climate. Projects that relied on groundwater and pumped too much from underground aquifers created subsidence and salinization. Salinization of irrigation water damaged the crops and seeped into drinking water. Pests and pathogens also thrived in the irrigation canals or ponds full of still water, which created regional outbreaks of diseases like malaria and schistosomiasis. Governments also used irrigation schemes to encourage migration, especially of more desirable populations into an area. Additionally, some of these large nationwide schemes failed to pay off at all, costing more than any benefit gained from increased crop yields. | Irrigation | Wikipedia | 374 | 42261 | https://en.wikipedia.org/wiki/Irrigation | Technology | Horticultural techniques | null |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.