title: Bulgars

text: In nomadic society the tribes were political organizations based on kinship, with diffused power. Tribes developed according to the relation with sedentary states, and only managed to conquer them when had social cohesion. If the raiding by the nomads had negative effect on the economic development of the region it could significantly slow down their own social and cultural development. In a nomadic state the nomad and sedentary integration was limited, and usually had vassal tribute system.


title: Bulgars

text: When the Bulgars arrived in the Balkan their first generations probably still lived a nomadic life in yurts, but they quickly adopted the sunken-featured building of rectangular plan and sedentary or seasonal lifestyle of the Slavs and autochthonous population. The Bulgar and Slavic settlements cannot be distinguished other than by the type of biritual cemeteries.


title: Bulgars

text: The Bulgars, at least the Danubian Bulgars, had a well-developed clan and military administrative system of "inner" and "outer" tribes, governed by the ruling clan. They had many titles, and according to Steven Runciman the distinction between titles which represented offices and mere ornamental dignities was somewhat vague. Maenchen-Helfen theorized that the titles of the steppe peoples did not reflect the ethnicity of their bearers. According to Magnus Felix Ennodius, the Bulgars did not have nobility, yet their leaders and common men became noblemen on the battle field, indicating social mobility. Tribute-paying sedentary vassals, such as the Slavs and Greek-speaking population, formed a substantial and important part of the "khanate"'s maintenance.


title: Bulgars

text: The ruler title in Bulgar inscriptions was "khan"/"kana". A counterpart of the Greek phrase ("ho ek Theou archon") was also common in Bulgar inscriptions. The "kavhan" was the second most important title in the realm, seemingly chief official. Some Bulgar inscriptions, written in Greek and later in Slavonic, refer to the Bulgarian rulers respectively with the Greek title "archon", or the Slavic titles "knyaz" and "tsar".


title: Bulgars

text: There are several possible interpretations for the ruler title, "kana sybigi", mentioned in six inscriptions by the Khan Omurtag and two by Malamir. Among the proposed translations for "sybigi" or "subigi" are "lord of the army", from the reconstructed Turkic phrase "syu-beg" (army master) paralleling the attested Orkhon Turkic "syubashi". Runciman and J. B. Bury considered "ubige" or "uvege" to be related to the Cuman-Turkic "öweghü" (high, glorious); "bright, luminous, heavenly"; and more recently "(ruler) from God", from the Indo-European "*su-" and "baga-", i.e. "*su-baga". Florin Curta noted the resemblance in the use of the "kana sybigi" with the Byzantine name and title "basileus".


title: Bulgars

text: Members of the upper social class bore the title "boila" (later "boyar"). The nobility was divided onto "small" and "great" boilas. In the 10th century, there were three classes of boyars: the six "great" boilas, the "outer" boilas, and the "inner" boilas, while in the mid-9th century there were twelve "great" boyars. The "great" boilas occupied military and administrative offices in the state, as well the council where they gathered for decisions on important matters of state.


title: Bulgars

text: "Bagaïns" were the lesser class of the nobility, probably a military class which also participated in the council. The title "bagatur", once as "bogotor", is found in several instances within the inscriptions. It derives from Turkish "bagadur" (hero) and was a high military rank. The Bulgarian military commander who was defeated by the Croats in the Battle of the Bosnian Highlands (926) was called Alogobotur, which is actually a title comprised by "alo" (considered Turkic "alp, alyp"; chief) and "bagatur".


title: Bulgars

text: There are several title associations with uncertain meaning, such as "boila kavkhan", "ičirgu boila", "kana boila qolovur", "bagatur bagain", "biri bagain", "setit bagain" and "ik bagain".


title: Bulgars

text: "Kolober" (or "qolovur"), a rank title, is cited in two inscriptions, and it derives from the Turkish term for a guide, "golaghuz". The title "župan", also once as "kopan" in the inscriptions, was often mentioned together with the bearer's name. They were traditionally seen as Slavic chiefs. It seems to have meant "head of a clan-district", as among the South Slavs (Croats, Serbs) where it was more widely used, it meant "head of a tribe" with a high district and court function.


title: Bulgars

text: The title "tarkhan" probably represented a high military rank, similar to the Byzantine "strategos", of the military governor of a province. The variations "kalutarkan" and "buliastarkan" are considered to be officers at the head of the "tarkans". Curta interpreted the title "zhupan tarqan" as ""tarqan of (all the) zhupans"".


title: Bulgars

text: Although it was not recorded on inscriptions, the title "sampses" is considered to be related to the royal court. The title "tabare" or "iltabare", which derives from the old Turkish "ältäbär", like "sampses" is not mentioned on inscriptions, but is related to the legates and ambassadors.


title: Bulgars

text: The Anastasius Bibliothecarius listed Bulgarian legates at the Council at Constantinople in 869–870. They were mentioned as Stasis, Cerbula, Sundica ("vagantur"="bagatur"), Vestranna ("iltabare"), Praestizisunas ("campsis"), and Alexius Hunno ("sampsi").


title: Bulgars

text: Very little is known about the religion of the Bulgars, but it is believed to have been monotheistic. In Greek language inscriptions from pagan Danube Bulgaria, Bulgar monarchs describe themselves as "ruler from God", indicating authority from a divine origin, and making an appeal to the deity's omniscience. Presian's inscription from Philippi (837) states:


title: Bulgars

text: It is traditionally assumed that the God in question was the Turkic supreme sky deity, Tengri. In the Chinese transcription as "zhenli", and Turkic as "Tangara" and "Tengeri", it represents the oldest known Turco-Mongolian word. Tengri may have originated in the Xiongnu confederacy, which settled on the frontiers of China in the 2nd century BC. The confederacy probably had both pre-Turkic and pre-Mongolian ethnic elements. In modern Turkish, the word for god, "Tanrı", derives from the same root.


title: Bulgars

text: Tengrism apparently engaged various shamanic practices. According to Mercia MacDermott, Tangra was the male deity connected with sky, light and the Sun. The cult incorporated Tangra's female equivalent and principle goddess, Umay, the deity of fertility. Their tamgha , which can be frequently found in early medieval Bulgaria is associated with deity Tangra. However, its exact meaning and use remains unknown. The most sacred creatures to Tangra were horses and eagles, particularly white horses. Broze amulets with representations of the Sun, horses and other animals were found at Bulgar archeological sites. This could explain the variety of Bulgars taboos, including those about animals.


title: Bulgars

text: Ravil Bukharaev believed that such an autocratic and monotheistic religionhenotheism, as seen in the report by Ahmad ibn Fadlan (10th century) about the Oghuz Turks, kindred to the Bulgars, made the acceptance of Islam more natural and easier in Volga Bulgaria:


title: Bulgars

text: Another mention of Tengri is on the severely damaged Greek inscription found on a presumed altar stone near Madara, tentatively deciphered as "Khan "sybigi" Omurtag, ruler from god...was...and made sacrifice to god Tangra..."itchurgu boila"...gold". An Ottoman manuscript recorded that the name of God, in Bulgarian, was "Tängri".


title: Bulgars

text: A piece of ethnographic evidence which has been invoked to support the belief that the Bulgars worshipped Tengri/Tangra is the relative similarity of the name "Tengri" to "Tură", the name of the supreme deity of the traditional religion of the Chuvash people, who are traditionally regarded as descendants of the Volga Bulgars. Nevertheless, the Chuvash religion today is markedly different from Tengrism and can be described as a local form of polytheism, due to pagan beliefs of the forest dwellers of Finnic origin, who lived in their vicinity, with some elements borrowed from Islam.


title: Bulgars

text: Paganism was closely connected with the old clan system, and the remains of totemism and shamanism were preserved even after the crossing of Danube. The Shumen plate in the archaeological literature is often associated with shamanism. In the 9th century, it was recorded that before a battle the Bulgars ""used to practice enchantments and jests and charms and certain auguries"". Liutprand of Cremona reported that Baian, son of Simeon I (893–927), could through "magicam" transform into a wolf. Clement of Ohrid reported the worship of fire and water by the Bulgars, while in the 11th century Theophylact of Ohrid remembered that before the Christianization the Bulgars respected the Sun, Moon and the stars, and sacrificed dogs to them.


title: Bulgars

text: Allegedly, the Dulo clan had the dog as its sacred animal. To this today Bulgarians still use the expression "he kills the dog" to mean "he gives the orders", a relic of the time when the Dulo Khan sacrificed a dog to the deity Tangra. Remains of dog and deer have been found in Bulgars graves, and it seems the wolf also had a special mythological significance. The Bulgars were bi-ritual, either cremating or burying their dead, and often interred them with personal objects (pottery, rarely weapons or dress), food, and sacred animals.


title: Bulgars

text: Because of the cult of the Sun, the Bulgars had a preference for the south. Their main buildings and shrines faced south, as well their yurts, which were usually entered from the south, although less often from the east. Excavations showed that Bulgars buried their dead on a north–south axis, with their heads to the north so that the deceased "faced" south. The Slavs practiced only cremation, the remains were placed in urns, and like the Bulgars, with the conversion to Christianity inhumed the dead on west–east axis. The only example of a mixed Bulgar-Slavic cemetery is in Istria near ancient Histria, on the coast of the Black Sea.


title: Bulgars

text: D. Dimitrov has argued that the Kuban Bulgars also adopted elements of Iranian religious beliefs. He noticed Iranian influences on the cult of the former Caucasian Huns capital Varachan (Balanjar), making a religious syncretism between the principal Turkic deity Tengri and the Iranian sun god Hvare. Dimitrov cited the work by V.A. Kuznetsov, who considered the resemblance between the layout of the Zoroastrian temples of fire and the Kuban Bulgar centre, Humarin citadel, situated 11 km to the north of the town Karachayevsk, where the pottery belonged to the Saltovo-Mayaki culture. Kuznecov also found a connection in the plan of the Danube Bulgars sanctuaries at Pliska, Veliki Preslav, and Madara. The architectural similarities include two squares of ashlars inserted one into another, oriented towards the summer sunrise. One of these sites was transformed into a Christian church, which is taken as evidence that they served a religious function.


title: Bulgars

text: The view of the Parthian and Sasanian influence, which Franz Altheim also argued, is considered debatable, showing the cultural impact of the Iranian world on communities in the Pontic–Caspian steppe. Many scholars believe that the square shape, with the north–south and east–west axis of the Bulgar sacral monuments is very similar to those of Turkic khagans in Mongolia. However, that the Bulgar residence in Pliska and Palace of Omurtag were inspired by the Byzantine architecture is considered indisputable.


title: Bulgars

text: Christianity had already begun to penetrate, probably via their Slavic subjects, when it was adopted in the First Bulgarian Empire by Knyaz Boris I in 865 as a state religion. There was interest in Islam as well, seen in the book "Answers to the Questions of the King of the Burgar addressed to him about Islam and Unity" by the Abbasid caliph Al-Ma'mun (813–833) for the Pontic/Bosporan Bulgars, while it was officially adopted in Volga Bulgaria as a state religion in 922.


title: Bulgars

text: The origin and language of the Bulgars has been the subject of debate since around the start of the 20th century. It is generally accepted that at least the Bulgar elite spoke a language that was a member of the Oghur branch of the Turkic language family, alongside the now extinct Khazar and the solitary survivor of these languages, Chuvash. Some scholars suggest Hunnic had strong ties with Bulgar and to modern Chuvash and classify them as separate Hunno-Bulgar languages.


title: Bulgars

text: According to P. Golden this association is apparent from the fragments of texts and isolated words and phrases preserved in inscriptions. In addition to language, their culture and state structure retain many Central Asian features. Military and hierarchical terms such as "khan/qan", "kanasubigi", "qapağan", "tarkan", "bagatur" and "boila" appear to be of Turkic origin. The Bulgar calendar within the "Nominalia of the Bulgarian khans" had a twelve-year animal cycle, similar to the one adopted by Turkic and Mongolian peoples from the Chinese, with animal names and numbers deciphered as Turkic. Tengri (in Bulgar "Tangra/Tengre") was their supreme god.


title: Bulgars

text: Bulgar inscriptions were written mostly in Greek or Cyrillic characters, most commonly in Greek or Graeco-Bulgar, sometimes with Slavic terms, thus allowing scholars to identify some of the Bulgar glosses. Several Bulgar inscriptions were found in Northeastern Bulgaria and parts of Romania, written in runes similar to the Old Turkic alphabet; they apparently have a sacral meaning. Altheim argued that the runes were brought into Europe from Central Asia by the Huns, and were an adapted version of the old Sogdian alphabet in the Hunnic/Oghur Turkic language. The custom of stone engravings are considered to have Sasanian, Turkic and Roman parallels. The Madara Rider resembles work of the Sasanian rock relief tradition, but its actual masonry tradition and cultural source is unknown.


title: Bulgars

text: The Danubian Bulgars were unable to alter the predominantly Slavic character of Bulgaria, seen in the toponymy and names of the capitals Pliska and Preslav. They preserved their own native language and customs for about 200 years, but a bilingual period was recorded since the 9th century. Golden argued that Bulgar Turkic almost disappeared with the transition to Christianity and Slavicisation in the middle of the 9th century. When the ruling class abandoned its native language and adopted Slavic, according to Jean W. Sedlar, it was so complete that no trace of Turkic speech patterns remained in Old Slavic texts. The Bulgarian Christian Church used Slavic dialect from Macedonia.


title: Bulgars

text: Among Bulgarian academics, notably Petar Dobrev, a hypothesis linking the Bulgar language to the Iranian languages (Pamir) has been popular since the 1990s. Most proponents still assume an intermediate stance, proposing certain signs of Iranian influence on a Turkic substrate. The names Asparukh and Bezmer from the "Nominalia" list, for example, were established as being of Iranian origin. Other Bulgarian scholars actively oppose the "Iranian hypothesis". According to Raymond Detrez, the Iranian theory is rooted in the periods of anti-Turkish sentiment in Bulgaria and is ideologically motivated. Since 1989, anti-Turkish rhetoric is now reflected in the theories that challenge the thesis of the proto-Bulgars' Turkic origin. Alongside the Iranian or Aryan theory, there appeared arguments favoring an autochthonous origin.


title: Bulgars

text: Due to the lack of definitive evidence, modern scholarship uses an ethnogenesis approach in explaining the Bulgars origin. More recent theories view the nomadic confederacies, such as the Bulgars, as the formation of several different cultural, political and linguistic entities that could dissolve as quickly as they formed, entailing a process of ethnogenesis.


title: Bulgars

text: According to Walter Pohl, the existential fate of the tribes and their confederations depended on their ability to adapt to an environment going through rapid changes, and to give this adaptation a credible meaning rooted in tradition and ritual. Slavs and Bulgars succeeded because their form of organization proved as stable and as flexible as necessary, while the Pannonian Avars failed in the end because their model could not respond to new conditions. Pohl wrote that members of society's lower strata did not feel themselves to be part of any large-scale ethnic group; the only distinct classes were within the armies and the ruling elite.


title: Bulgars

text: Recent studies consider ethnonyms closely related with warrior elites who ruled over a variety of heterogeneous groups. The groups adopted new ideology and name as political designation, while the elites claimed right to rule and royal descent through origin myths.


title: Bulgars

text: When the Turkic tribes began to enter into the Pontic–Caspian steppe in the Post-Hunnic era, or as early as the 2nd century AD, their confederations incorporated an array of ethnic groups of newly joined Turkic, Caucasian, Iranian, and Finnic peoples. During their Western Eurasian migrations to the Balkans, they also came into contact with Armenian, Semitic, Slavic, Thracian and Anatolian Greek among other populations.


title: Bulgars

text: From the 6th to 8th centuries, distinctive Bulgar monuments of the Sivashovka type were built upon ruins of the late Sarmatian culture of the 2nd to 4th centuries AD, and the 6th century Penkovka culture of the Antes and Slavs. Early medieval Saltovo-Mayaki (an Alanic-based culture) settlements in the Crimea since the 8th century were destroyed by the Pechengs during the 10th century.


title: Bulgars

text: Although the older Iranian tribes were enveloped by the widespread Turkic migration into the Pontic–Caspian steppe, the following centuries saw a complete disappearance of both the Iranian and Turkic languages, indicating dominance of the Slavic language among the common people.


title: Bulgars

text: Genetic and anthropological researches have shown that the tribes of the Eurasian steppes were not always ethnically homogeneous, and were often unions of multiple ethnicities. Skeletal remains from Kazakhstan (Central Asia), excavated from different sites dating between the 15th century BC to the 5th century AD, have been analyzed. The distribution of east and west Eurasian lineages through time in the region agrees with available archaeological information. Prior to the 13th–7th century BC, all samples belong to European lineages, while later, an arrival of East Asian sequences that coexisted with the previous genetic substratum was detected. Hundreds of excavated mummies in the Tarim Basin (West China) have Caucasoid features, revealing the presence of an ancient Caucasoid substratum in East Asia. These findings are associated with the ancient Tocharians and Tocharian languages.


title: Bulgars

text: According to P. Golden, the Central Asian Turkic peoples have multiple points of origin and are a mixture of steppes ethnic groups. Eric Hobsbawm considered the languages to be "almost always semi-artificial constructs". Political processes, rather than linguistic, tribal or ethnic elements, created new communities. Golden noted that the Turkic tribes in the Western Eurasia since the 1st millennium BC had contacts with Proto-Indo-Europeans. Those tribes were considered by Golden to be the ancestors of the Oğuric Turks.


title: Bulgars

text: Recent blood and DNA studies of present-day populations in Central Asia confirm the extreme genetic heterogeneity. The latest DNA studies on Turkic people in Central Asia and Eastern Europe also confirm genetic heterogeneity, indicating that the Turkic tribal confederations included various mtDNA and Y-DNA haplogroups. A 2013 comparative genetic study shows that modern Bulgarians primarily are represented by the Western Eurasian Y haplogroups, with 40% belonging to haplogroups E-V13 and I-M423, and 20% to R-M17 (R-M198 and R-M458). Haplogroups common in the Middle East (J-M172, J-M267, and G-M201) and in South Western Asia (R-L23*) occur at frequencies of 19% and 5%, respectively. The central Asian and Altaic-Turkic haplogroups C, N and Q together occur at the negligible frequency of only 1.5% among Bulgarians. It could indicate that "a shared paternal ancestry between proto-Bulgarians and Altaic and Central Asian Turkic-speaking groups either did not exist or was negligible". However according to the Genetic Atlas of Human Admixture History by Hellenthal et al. 2014, using a chromosome painting, to follow the genetic admixture, only a small Northeast Asiatic DNA signal among Bulgarians (2,4%) might correspond to the whole genetic legacy left from the invasions of the Bulgars. The DNA studies of the Chuvash people, who speak a Turkic language (Chuvash), show that they are genetically related to Caucasians, Mediterraneans, and Middle Easterners, partially Central or Northern Europeans (Finnic), but with little Central Asian-Altaic gene flow. The DNA studies of the Tatars, Bashkirs and Russians in Chelyabinsk Oblast show European and Finnic impact on the Tatars; Caucasoid and East Asian impact were reported for the Bashkirs. Some aspects of genetic relationships were found between Tatars and Chuvashes, as well Bulgarians, which could support the view that the Tatars may be descendants of ancient Bulgars. It is currently unknown with which haplogroup the Bulgars should be associated; some scholars consider the possibility that only a cultural and low genetic influence was brought into the region.


title: Bulgars

text: A 2015 Bulgarian mtDNA study on 13 samples from the 8th–10th century suggests a Western Eurasian matrilineal origin for Proto-Bulgarians. The study established that "Proto-Bulgarians are positioned among South-Eastern and Southern European populations including modern Bulgarians. Proto-Bulgarians are genetically distant from Northern and Western Europeans and populations from the Near East and Caucasus. On the greatest distance from Proto-Bulgarians are Volga-Ural and Arabic populations." The study further mentions that "...proto-Bulgarians are genetically similar to modern Bulgarians and to certain South-Eastern European as well as Italian populations." Until now there's still not enough archaeogenetic data to confirm Turkic, Ugrian and/or Sarmatian origin and admixture of Proto-Bulgarian elite, however, Todor V. Chobanov and Svetoslav Samov in their research of available archaeological and genetical data presuppose "Proto-Bulgarians were a mixture of Late Sarmatians and older Caucasus populations, closely related to the Alans and preserving their genetic inheritance, even after arriving on the Balkans and mixing with Slav peoples and the remnants of the local Late Antiquity peoples".


title: Bulgars

text: The paleoanthropological material from all sites in Volga region, Ukraine and Moldova attributed to the Bulgars testify complex ethno-cultural processes. The material shows the assimilation between the local population and the migrating newcomers. In all sites can be traced the anthropological type found in the Zlivka necropolis near the village of Ilichevki, the district of Donetsk, of brachiocranic Caucasoid with small East Asian admixtures but with Bulgar males being more Mongoloid than females. Despite the morphological proximity, there is a visible impact of the local population, in the Volga region of Finnic and ancient Turkic, in Ukraine of Sarmatian-Alans, and in Moldova of Slavic people. The comparative analysis showed large morphological proximity between the medieval and modern population of the Volga region. The examined graves in Northern Bulgaria and Southern Romania showed different somatic types, including Caucasoid-Mediterranean and less often East Asian.


title: Bulgars

text: The pre-Christian burial customs in Bulgaria indicate diverse social, i.e. nomadic and sedentary, and cultural influences. In some necropolises specific to the Danube Bulgars, artificial deformation was found in 80% of the skulls. The Bulgars had a special type of shamanic "medicine-men" who performed trepanations of the skull, usually near the sagittal suture. This practice had a medical application, as well as a symbolic purpose; in two cases the patient had brain problems. According to Maenchen-Helfen and Rashev, the artificial deformation of skulls, and other types of burial artifacts in Bulgars graves, are similar to those of the Sarmatians, and Sarmatized Turks or Turkicized Sarmatians of the post-Hunnic graves in the Ukrainian steppe.


title: Bulgars

text: In modern ethnic nationalism there is some "rivalry for the Bulgar legacy" (see Bulgarism). The Volga Tatars and Chuvash people, are said to be descended from the Volga Bulgars, and there may have been ethnogenic influences on the Bashkirs, Karachays and Balkars also.


title: Mass suicide

text: Mass suicide sometimes occurs in religious settings. In war, defeated groups may resort to mass suicide rather than being captured. Suicide pacts are a form of mass suicide that are sometimes planned or carried out by small groups of depressed or hopeless people. Mass suicides have been used as a form of political protest.


title: Mass suicide

text: Attitudes towards mass suicide change according to place and circumstance. People who resort to mass suicide rather than submit to what they consider intolerable oppression sometimes become the focus of a heroic myth. Such mass suicides might also win the grudging respect of the victors. On the other hand, the act of people resorting to mass suicide without being threatened – especially, when driven to this step by a charismatic religious leader, for reasons which often seem obscure – tends to be regarded far more negatively.


title: Mass suicide

text: In the 19th century British Guiana, Awakaipu, an Arekuna shaman, established a settlement of indigenous tribesmen called "Bekeranta" (Berbice Creole Dutch, meaning "Land of the White People") at the base of Kukenán-tepui. In approximately 1843 or 1844, Awakaipu instructed his followers to violently murder each other in order to reincarnate themselves as white people. Unofficial figures put the death toll at around 400, which included men, women, and children.


title: Mass suicide

text: Yogmaya Neupane and her group of 67 disciples committed the biggest mass suicide (Jal-Samadhi) in Nepali history, by jumping into the Arun River (China–Nepal) in 1941.


title: Mass suicide

text: On November 18, 1978, 918 Americans, including 276 children, died in Peoples Temple–related incidents, including 909 members of the Temple, led by Jim Jones, in Jonestown, Guyana. A tape of the Temple's final meeting in a Jonestown pavilion contains repeated discussions of the group committing "revolutionary suicide", including reference to people taking the poison and the vats to be used.


title: Mass suicide

text: On that tape, Jones tells Temple members that the Soviet Union, with whom the Temple had been negotiating a potential exodus for months, would not take them after the Temple had murdered Member of Congress Leo Ryan, NBC reporter Don Harris and three others at a nearby airstrip. When members apparently cried, Jones counseled "Stop this hysterics. This is not the way for people who are Socialists or Communists to die. No way for us to die. We must die with some dignity." At the end of the tape, Jones concludes: "We didn't commit suicide, we committed an act of revolutionary suicide protesting the conditions of an inhumane world."


title: Mass suicide

text: The people in Jonestown died of an apparent cyanide poisoning, except for Jones (who died of an injury consistent with a self-inflicted gunshot wound) and his personal nurse. The Temple had spoken of committing "revolutionary suicide" in prior instances, and members had previously drunk what Jones told them was poison at least once before, but the "Flavor Aid" drink they ingested at that time contained no poison. Concurrently, four other members died in the Temple's headquarters in Georgetown. Four months later, Michael Prokes, one of the initial survivors, also committed suicide.


title: Mass suicide

text: From 1994 to 1997, the Order of the Solar Temple's members began a series of mass suicides, which led to roughly 74 deaths. Farewell letters were left by members, stating that they believed their deaths would be an escape from the "hypocrisies and oppression of this world". Added to this they felt they were "moving on to Sirius". Records seized by the Quebec police showed that some members had personally donated over $1 million to the group's leader, Joseph Di Mambro.


title: Mass suicide

text: There was also another attempted mass suicide of the remaining members, which was thwarted in the late 1990s. All the suicide/murders and attempts occurred around the dates of the equinoxes and solstices, which likely held some relation to the beliefs of the group.


title: Mass suicide

text: From March 24 to 27, 1997, 39 followers of Heaven's Gate died in a mass suicide in Rancho Santa Fe, California, which borders San Diego to the north. These people believed, according to the teachings of their group, that through their suicides they were "exiting their human vessels" so that their souls could go on a journey aboard a spaceship they believed to be following comet Hale–Bopp. Some male members of the group underwent voluntary castration in preparation for the genderless life they believed awaited them after the suicide.


title: Mass suicide

text: In May 1997, two Heaven's Gate members who had not been present for the mass suicide attempted suicide, one succeeding, the other becoming comatose for two days and then recovering. In February 1998, the survivor, Chuck Humphrey, committed suicide.


title: Mass suicide

text: In August 2004, ten dead bodies were discovered, all in a sleeping position, inside a two-story house located at Béchard Lane in the suburb of Saint Paul, Vacoas-Phoenix on the island of Mauritius. They had been missing for a number of days, and large loans had been contracted by some of the victims a short time before their deaths. Several of them were active members of the Eckankar sect. The main gate and all doors of the house had been locked from the inside, and the interior was in tidy order when police broke into the house.


title: Mass suicide

text: In 2007, in Mymensingh, Bangladesh, a family of nine, all members of a novel "Adam's cult", committed mass suicide by hurling themselves under a train. Diaries recovered from the victims' home, the "Adam House", related they wanted a pure life as lived by Adam and Eve, freeing themselves from bondage to any religion, and refusing contact with any outsiders. After leaving Islam, they fell out of boundaries of any particular religion.


title: Mass suicide

text: The Burari deaths, also "Burari case" and "Burari kaand", refers to the deaths of eleven family members of the Chundawat family from Burari, India, in 2018. Ten family members were found hanged, while the oldest family member, the grandmother, was strangled. The bodies were found on 1 July 2018; in the early morning after the death. The police have ruled the deaths as mass suicide, with an angle of shared psychosis being investigated.


title: Mass suicide

text: On March 17, 2000, 778 members of the Movement for the Restoration of the Ten Commandments of God died in Uganda. The theory that all of the members died in a mass suicide was changed to mass murder when decomposing bodies were discovered in pits with signs of strangulation, while others had stab wounds. The group had diverged from the Roman Catholic Church in order to emphasize apocalypticism and alleged Marian apparitions. The group had been called an inward-looking movement, that wore matching uniforms, and restricted their speech to avoid saying anything dishonest or sinful. On the suicide itself, locals said they held a party, at which 70 crates of soft drinks and three bulls were consumed. This version of events has been criticized, most notably by Irving Hexham, and a Ugandan source states that even today, "no one can really explain the whys, hows, whats, where, when, etc."


title: Mass suicide

text: Training centre for release of the Atma-energy was known for a police and media scare, in which an alleged attempt to commit ritual suicide took place in Teide National Park in Tenerife in 1998.


title: Adel Taarabt

text: Adel Taarabt (; born 24 May 1989) is a Moroccan professional footballer who plays as an attacking midfielder or winger for Emirati club Al-Nasr and the Morocco national team.


title: Adel Taarabt

text: Taarabt began his playing career in France at Lens before moving to English Premier League club Tottenham Hotspur in 2007. Taarabt then moved to Queens Park Rangers on loan in July 2009. He was signed permanently in August 2010 and quickly established himself at Loftus Road. QPR were relegated in 2013 and in the ensuing summer, Taarabt moved to Fulham on loan. After another loan to AC Milan in Italy, Taarabt signed a long-term deal with Primeira Liga club Benfica in 2015, who loaned him out to Italian side Genoa two years later.


title: Adel Taarabt

text: Taarabt made his Morocco debut in February 2009, and scored his first international goal the following month. He represented the country at the 2012 Africa Cup of Nations.


title: Adel Taarabt

text: Taarabt was born in Fez, Morocco. At a young age, his family moved to a small town called Berre-l'Étang, Bouches-du-Rhône, France. He began his career at Lens in 2004, and played 14 matches for RC Lens B in the Championnat de France amateur. He made one first team appearance for Lens during the 2006–07 season.


title: Adel Taarabt

text: Still at the age of 17, Taarabt signed for Tottenham Hotspur on a long-term loan on 2 January 2007 after the club offered to integrate him quickly into the first team to offer him maximum playing time. Within two months, he made his first senior appearance in a Spurs shirt, entering as an 87th-minute substitute for Pascal Chimbonda against local rivals West Ham United in a 4–3 away victory on 4 March. On 7 April, he made the only other appearance of his loan, in a 1–0 defeat at another local rival, Chelsea; he replaced Teemu Tainio after 64 minutes.


title: Adel Taarabt

text: Tottenham signed Taarabt permanently on 8 June. He scored his first goal for Spurs in a pre-season friendly against Stevenage Borough on 7 July. He made his first of six appearances in the 2007–08 season against Derby County in the 4–0 win on 18 August, entering the 71st minute for Wayne Routledge. He won a crucial free kick, scored by Dimitar Berbatov in a 4–3 win at Upton Park sparking wild scenes in the away end.


title: Adel Taarabt

text: At the beginning of the 2008–09 season, Taarabt was among a group of players not given a squad number by then manager Juande Ramos, and also banned from the first-team training ground. He was given his old number when Harry Redknapp took over team management, but his only Premier League appearance that season came in a goalless North London derby on 8 February 2009, playing three minutes in place of Aaron Lennon.


title: Adel Taarabt

text: On 13 March 2009, Taarabt joined Championship club Queens Park Rangers on loan until the end of the 2008–09 season. He scored his first goal for QPR in a 2–1 win over Bristol City. His loan spell was cut short after he suffered a knee injury which required surgery.


title: Adel Taarabt

text: On 23 July 2009, Taarabt rejoined QPR on a season-long loan for the 2009–10 season. On 1 October, Taarabt scored a "wonder strike" in a match against Preston North End. He collected the ball on his chest inside the QPR half, dribbled 20 yards past three players and curled in a shot from 25 yards.


title: Adel Taarabt

text: Tottenham confirmed in October 2009 that Taarabt could stay at QPR for the season providing that a Premier League club did not make a bid for him in the January transfer window. QPR were unable to make the transfer permanent because they could not afford the £4.5 million valuation placed on Taarabt by Spurs.


title: Adel Taarabt

text: In March 2010, Taarabt was quoted in an interview as being sorry he had signed for Tottenham, saying, "The big mistake was to sign for Tottenham and not go to another club when I first came over." He stated he wished he had signed for Arsenal instead but had opted for Spurs after Damien Comolli moved from being a scout at Arsenal to director of football at Spurs. He said he felt he would have been given more chances to play at Arsenal and was advised at the time not to sign for Spurs by his friends Armand Traoré and Abou Diaby, who played for Arsenal. Taarabt went on to state his intention to sign for one of the top clubs in Spain: "I hope to be playing for one of the top four in Spain next season – Real Madrid, Barcelona, Valencia or Sevilla. I have contact with good teams and I know that they want me. Now I just have to hope they can agree a deal with Tottenham."


title: Adel Taarabt

text: In January 2011, Taarabt was interviewed by the "Evening Standard" in which he said, "The man who took me to Tottenham was Damien Comolli. He was at Arsenal then. But, when I was going to go to Arsenal, he moved to Tottenham. He told me: 'Come to Tottenham. We want to do like they do at Arsenal and take the best young players in the world. You're going to have a better chance there.' I believed him. This was a mistake and I regret it. Tottenham tried to do it like Arsenal but it's a different culture. I would have had a better chance at Arsenal. I would progress with Arsène Wenger. He is a legend in France, one of the best managers in the world."


title: Adel Taarabt

text: Taarabt was to make his debut as a full QPR player, as the club signed the Moroccan for a reported £1 million. The contract stipulated that Tottenham would receive 40% of any future transfer profit, in addition to the payments already made. His move was proved to be one of the bargains of the season as Taarabt scored 19 goals in 44 league appearances that season for the West London club. With his unpredictable skill and reputation for never giving the opposition defence an easy 90 minutes, Taarabt went on to win the Championship Player of the Year award and gained a place in the Championship's best XI, which also featured teammate Paddy Kenny.


title: Adel Taarabt

text: In March 2011, Taarabt missed two matches when he returned to France for family matters as one of his cousins had been killed. In the return fixture Morocco manager Erik Gerets opted to drop Taarabt to the substitutes' bench. Taarabt decided to not turn up to the international fixture and vowed to never play for his country again. However, several months later, Taarabt wanted to play for Morocco again, which Gerets reluctantly allowed, but said that if Taarabt acted irrationally again, he would not play for his country while he was in charge.


title: Adel Taarabt

text: Some notable moments during the season were against Cardiff City (an away 2–2 draw), where Taarabt picked up a brace, scoring a wonder goal in the process. During the home match against the same opposition, Taarabt scored the winner which took QPR back to the top of the Championship.


title: Adel Taarabt

text: The 2011–12 season marked Taarabt's first real foray into the Premier League, for although having been featured in English football's highest tier as a Tottenham player, he had never made a breakthrough into the Spurs' starting XI. The start of the season held much optimism for both QPR and Taarabt, yet this soon gave way to speculation that he would move away, and his name was associated with the likes of Paris Saint-Germain and Napoli. This was coupled with the arrival of Joey Barton in the August transfer window, who was immediately installed as captain, taking the role from Taarabt.


title: Adel Taarabt

text: These factors had the unfortunate effect of unsettling Taarabt and he was unable to recreate his form from the previous season. By early November, he had taken over 20 shots yet scored zero goals. Prior to this, he had often let his temper get the better of him. During the 6–0 loss away to Fulham on 2 October, he was substituted at half-time. His attitude provoked criticism from his teammates, with Joey Barton being particularly vocal. Taraabt was again substituted at half-time for a poor showing in the 3–1 defeat at Tottenham and was subsequently omitted from the side for the matches against Manchester City and Stoke City. During this period, continued speculation linked him with PSG, and Warnock even admitted he would gladly accept an offer for Taraabt if the right one came along. Adel was considered the best Arab player of 2011 for the Argélia Le Buteur newspaper.


title: Adel Taarabt

text: Taraabt went on international duty and also had some minor injuries which also saw him left out of the side at this stage. Warnock was highly critical of the player's agents during this period and laid much of the blame for him being unsettled at their feet. He advised him to rethink the advice they had given him and said, "They won't make him better and I think it is a shame. Adel can always make money but he is better than that. I will be sad if he ends up going to make some money because I think he has great ability." Still left out of the side throughout most of November, subsequent injuries to his teammates saw a recall, however, and he was commended for his performance in the 2–0 loss to Manchester United on 18 December. He sustained this level of improved performance against Sunderland and Swansea City. On 31 March, Taarabt scored the first goal in QPR's victory over Arsenal, and was also voted Man of the Match. Taarabt followed up his goal against Arsenal by scoring a long-range free-kick, the winning goal in a victory over his former club Tottenham on 21 April. He was also shown his first red card in English football in the same match for a second bookable offence.


title: Adel Taarabt

text: On 11 July 2012, Taarabt signed a new three-year contract with QPR, keeping him at the club until June 2016. On 1 October 2012, he scored his first goal of the season against West Ham United with a dipping long-range shot after dribbling past two players. He scored his second goal in three matches with an emphatic volley away against West Bromwich Albion on 6 October. On 15 December, he scored both goals in QPR's first victory of the 2012–13 season, a 2–1 win over West London rivals Fulham, the second with a mazy dribble ending with a finish on the outside of his foot. Manager Harry Redknapp praised Taarabt by stating, "It was one of the all-time great performances, I felt." On 2 January 2013, in QPR's second win of the season, a 1–0 away victory over rivals Chelsea, Taarabt was played in an unfamiliar striker position, gaining the Man of the Match award and assisting the only goal, described as "Pelé-esque".


title: Adel Taarabt

text: Taarabt joined Premier League side Fulham on a season-long loan on 7 August 2013. He made his Fulham debut in an away match against Sunderland, where he played the full 90 minutes. He scored his first goal for the club against Burton Albion in the League Cup on 27 August 2013.


title: Adel Taarabt

text: On 30 January 2014, Taarabt signed for AC Milan until the end of the season, demonstrating the "Rossoneri"'s renewed ambition on the transfer market. He scored his first goal for Milan eight minutes into his debut, against Napoli, having tackled the ball in his own half and dribbling halfway across the pitch to score from outside the box in a 3–1 loss. On 19 February, he made his debut in the UEFA Champions League, in the first leg of the round of 16 in a 1–0 loss at the San Siro against Atlético Madrid.


title: Adel Taarabt

text: In the 2014 summer season, Taarabt returned from his loan spells back to QPR, but after starting in the League Cup match against Burton Albion on 27 August, only came on as a substitute in the away match against West Ham. Responding to a journalist's question, QPR manager Harry Redknapp stated after his team's home defeat against Liverpool, "Taarabt is not injured. He's not fit. He's not fit to play football unfortunately. He played in a reserve game the other day and I could have run about more than he did. I can't pick him." Taarabt responded that Redknapp was "making excuses because QPR are losing games", adding, "[M]aybe he expects me to make more tackles. I am not this type of player."


title: Adel Taarabt

text: On 12 June 2015, Taarabt signed a five-year contract with Portuguese champions Benfica on €4 million transfer fee. On 10 January 2017, he joined Italian club Genoa on a loan deal until June 2018.


title: Adel Taarabt

text: After seven months with Benfica's reserve team, Taarabt returned to the first-team in February 2019, making his debut on 30 March 2019 as a 71st-minute substitute in a 1–0 home win over Tondela in Primeira Liga.


title: Adel Taarabt

text: During the 2019–20 season, Taarabt established himself as a regular starter for Benfica in an unfamiliar defensive midfield position. On 1 September 2022, Benfica announced the termination of his contract.


title: Adel Taarabt

text: Taarabt represented France at under-16, under-17 and under-18 levels, but opted to play for Morocco at senior level, saying, "I felt the time was right when I was given this opportunity". On 11 February 2009, he played his first international match with Morocco in a friendly against Czech Republic in Casablanca. He also made an appearance on 29 March during Morocco's 2010 FIFA World Cup qualifier 2–1 defeat against Gabon.


title: Adel Taarabt

text: Taarabt scored his first international goal on his first start on 31 March 2009 in a friendly 2–0 victory over Angola. On 6 September 2009, he scored his first goal in a competitive international match against Togo in the 2010 World Cup qualification after he broke through the opposing defence in stoppage time.


title: Adel Taarabt

text: On 3 June 2011, Taarabt decided to end his international career the day after being dropped to the bench for an Africa Cup of Nations qualifier against Algeria. He reneged on that decision, returning on 9 October 2011 for their last qualifier against Tanzania. Taarabt scored a free-kick that would end up being the winning goal and sealing Morocco's qualification. He made two substitute appearances in a group stage exit.


title: Adel Taarabt

text: Taarabt was omitted from Morocco's squad for the 2013 Africa Cup of Nations by head coach Rachid Taoussi.


title: Adel Taarabt

text: After five years without making an international appearance, Taarabt was recalled to the national squad in September 2019. He made his return as a substitute in a friendly match against Burkina Faso on 6 September. Four days later, he was selected to start against Niger and assisted the only goal of the match for midfield partner Walid El Karti.


title: Adel Taarabt

text: Taarabt is a Muslim and stated in an interview in June 2010 that this religion has had a significant impact on his life as a footballer:


title: Adel Taarabt

text: "Being a Muslim has had a big impact on my professional life. As Muslims, we don't drink alcohol, we don't smoke, so essentially we've become healthier, more professional footballers because of our lifestyle. Before every game, I perform salat. Without it, I just don't feel confident. I make sure I pray after a match, too – to give thanks and be grateful for the stamina and strength God graced me with."


title: Adel Taarabt

text: Taarabt credits his parents with keeping his religion in his life, and his father for encouraging him to play professional football.


title: Ashoka Chakra

text: The Ashoka Chakra is a depiction of the Dharmachakra. It is called so because it appears on a number of edicts of Ashoka, most prominent among which is the Lion Capital of Ashoka. The most visible use of the Ashoka Chakra today is at the centre of the Flag of India (adopted on 22 July 1947), where it is rendered in a navy blue colour on a white background, replacing the symbol of "charkha" (spinning wheel) of the pre-independence versions of the flag. It is also shown in the Ashoka Chakra medal which is the highest award for gallantry in peacetime.


title: Ashoka Chakra

text: When Gautama Buddha achieved enlightenment at Bodh Gaya, he came to Sarnath. There, he found his five disciples Assaji, Mahānāman, Kondañña, Bhaddiya and Vappa, who had earlier abandoned him. He introduced his first teachings to them, thereby establishing the Dharmachakra;. This is the motif taken up by Ashoka and portrayed on top of his pillars.


title: Ashoka Chakra

text: The 24 spokes represent the twelve causal links taught by the Buddha and paṭiccasamuppāda (Dependent Origination, Conditional Arising) in forward and then reverse order. The first 12 spokes represent 12 stages of suffering. Next 12 spokes represent no cause no effect. So, due to awareness of mind, formation of mental conditioning stops. This process stops the process of birth and death i.e. nibbāna. It also depicts the “wheel of time” . The twelve causal links, paired with their corresponding symbols, are:


title: Ashoka Chakra

text: Ashoka Chakra was included in the middle of the national flag of India.In fact, in 1942, in Varanasi, when Mohan Malviya invited Mahatma Gandhi to the Golden Jubilee celebrations of the university, Mahatma Gandhi also visited Sarnath.  There he saw the Ashoka chakra .  After this Gandhi used the Ashoka Chakra in the wheel of the flag.  The flag with a spinning wheel with 24 spokes led the Quit India Movement of 1942. The chakra intends to show that there is life in movement and death in stagnation. Dr B. R. Ambedkar was instrumental in reviving the legacy of Ashoka, and using the Ashokan Wheel on the flag was one of the ways where he tried to memorializing the Buddhist king.


title: Bocce

text: Having developed from games played in the Roman Empire, Bocce developed into its present form in Italy (where it is called ', the plural of the Italian word ' which means 'bowl' in the general sporting sense), it spread around Europe and also in regions to which Italians have migrated. In South America it is known as ', or "bolas criollas" ('Criollo balls') in Venezuela, and ' in south Brazil. The accessibility of bocce to people of all ages and abilities has seen it grow in popularity among Special Olympics programmes globally and it is now the third most played sport among Special Olympics athletes.


title: Bocce

text: The sport is also very popular on the eastern side of the Adriatic, especially in Croatia, Serbia, Montenegro, and Bosnia and Herzegovina, where the sport is known in Serbo-Croatian as ' ('playing '') or ' (colloquially also '). In Slovenia the sport is known as ' or colloquially 'playing '', or ' (from Italian ' and Venetian "", meaning 'balls'). There are numerous bocce leagues in the United States. Most have been founded by Italian Americans but contain members of all groups.


title: Bocce

text: Bocce is traditionally played on a natural soil or asphalt court up to in length and wide. While the court walls are traditionally made of wood or stone, many social leagues and Special Olympics programs now use inflatable 'Packabocce' PVC courts due to their portability and ease of storage. Bocce balls can be made of wood (traditional), metal, baked clay, or various kinds of plastic. Unlike lawn bowls, bocce balls are spherical and have no inbuilt bias.


title: Bocce

text: A game can be conducted between two players, or two teams of two, three, or four. A match is started by a randomly chosen side being given the opportunity to throw a smaller ball, the jack (called a ' ('little bocce') or ' ('bullet' or 'little ball') in Italian, depending on local custom), from one end of the court into a zone in length, ending from the far end of the court. If the first team misses twice, the other team is awarded the opportunity to place the jack anywhere they choose within the prescribed zone. Casual play is common in reasonably flat areas of parks and yards lacking a Bocce court, but players should agree to the minimum and maximum distance the jack may be thrown before play begins.


title: Bocce

text: The side that first attempted to place the jack is given the opportunity to bowl first. Once the first bowl has taken place, the other side has the opportunity to bowl. From then on, the side which does "not" have the ball closest to the jack has a chance to bowl, up until one side or the other has used their four balls. At that point, the other side bowls its remaining balls. The object of the game is for a team to get as many of its balls as possible closer to the target ball (jack, boccino, pallino) than the opposing team. The team with the closest ball to the jack is the only team that can score points in any frame. The scoring team receives one point for each of their balls that is closer to the jack than the closest ball of the other team. The length of a game varies by region but is typically from 7 to 13 points.


title: Bocce

text: Players are permitted to throw the ball in the air using an underarm action. This is generally used to knock either the jack or another ball away to attain a more favorable position. Tactics can get quite complex when players have sufficient control over the ball to throw or roll it accurately.


title: Bocce

text: A variation called ' uses a metal ball, which is thrown overhand (palm down), after a run-up to the throwing line. In that latter respect, it is similar to the French boules game ' also known as '. A French variant of the game is called ', and (lacking the run-up) is more similar in some respects to traditional ".


title: Bocce

text: Another development, for persons with disabilities, is called ". It is a shorter-range game, played with leather balls on an indoor, smooth surface. Boccia was first introduced to the Paralympics at the 1984 New York/Stoke Mandeville Summer Games, and is one of the only two Paralympic sports that do not have an Olympic counterpart (the other being goalball).


title: Intensive care unit

text: An intensive care unit (ICU), also known as an intensive therapy unit or intensive treatment unit (ITU) or critical care unit (CCU), is a special department of a hospital or health care facility that provides intensive care medicine.


title: Intensive care unit

text: Intensive care units cater to patients with severe or life-threatening illnesses and injuries, which require constant care, close supervision from life support equipment and medication in order to ensure normal bodily functions. They are staffed by highly trained physicians, nurses and respiratory therapists who specialize in caring for critically ill patients. ICUs are also distinguished from general hospital wards by a higher staff-to-patient ratio and access to advanced medical resources and equipment that is not routinely available elsewhere. Common conditions that are treated within ICUs include acute respiratory distress syndrome, septic shock, and other life-threatening conditions.


title: Intensive care unit

text: Patients may be referred directly from an emergency department or from a ward if they rapidly deteriorate, or immediately after surgery if the surgery is very invasive and the patient is at high risk of complications.


title: Intensive care unit

text: In 1854, Florence Nightingale left for the Crimean War, where triage was used to separate seriously wounded soldiers from those with non-life-threatening conditions.


title: Intensive care unit

text: Until recently, it was reported that Nightingale’s method reduced mortality from 40% to 2% on the battlefield. Although this was not the case, her experiences during the war formed the foundation for her later discovery of the importance of sanitary conditions in hospitals, a critical component of intensive care.


title: Intensive care unit

text: In 1950, anesthesiologist Peter Safar established the concept of advanced life support, keeping patients sedated and ventilated in an intensive care environment. Safar is considered to be the first practitioner of intensive care medicine as a speciality.


title: Intensive care unit

text: In response to a polio epidemic (where many patients required constant ventilation and surveillance), Bjørn Aage Ibsen established the first intensive care unit in Copenhagen in 1953.


title: Intensive care unit

text: The first application of this idea in the United States was in 1955 by William Mosenthal, a surgeon at the Dartmouth-Hitchcock Medical Center. In the 1960s, the importance of cardiac arrhythmias as a source of morbidity and mortality in myocardial infarctions (heart attacks) was recognized. This led to the routine use of cardiac monitoring in ICUs, especially after heart attacks.


title: Intensive care unit

text: Common equipment in an ICU includes mechanical ventilators to assist breathing through an endotracheal tube or a tracheostomy tube; cardiac monitors for monitoring Cardiac condition; equipment for the constant monitoring of bodily functions; a web of intravenous lines, feeding tubes, nasogastric tubes, suction pumps, drains, and catheters, syringe pumps; and a wide array of drugs to treat the primary condition(s) of hospitalization. Medically induced comas, analgesics, and induced sedation are common ICU tools needed and used to reduce pain and prevent secondary infections.


title: Intensive care unit

text: The available data suggests a relation between ICU volume and quality of care for mechanically ventilated patients. After adjustment for severity of illnesses, demographic variables, and characteristics of different ICUs (including staffing by intensivists), higher ICU staffing was significantly associated with lower ICU and hospital mortality rates. A ratio of 2 patients to 1 nurse is recommended for a medical ICU, which contrasts to the ratio of 4:1 or 5:1 typically seen on medical floors. This varies from country to country, though; e.g., in Australia and the United Kingdom, most ICUs are staffed on a 2:1 basis (for high-dependency patients who require closer monitoring or more intensive treatment than a hospital ward can offer) or on a 1:1 basis for patients requiring extreme intensive support and monitoring; for example, a patient on a mechanical ventilator with associated anaesthetics or sedation such as propofol, midazolam and use of strong analgesics such as morphine, fentanyl and/or remifentanil.


title: Intensive care unit

text: International guidelines recommend that every patient gets checked for delirium every day (usually twice or as much required) using a validated clinical tool. The two most widely used are the Confusion Assessment Method for the ICU (CAM-ICU) and the Intensive Care Delirium Screening Checklist (ICDSC). There are translations of these tools in over 20 languages and they are used globally in many ICU's.


title: Intensive care unit

text: In the United States, up to 20% of hospital beds can be labelled as intensive-care beds; in the United Kingdom, intensive care usually will comprise only up to 2% of total beds. This high disparity is attributed to admission of patients in the UK only when considered the most severely ill.


title: Intensive care unit

text: Intensive care is an expensive healthcare service. A recent study conducted in the United States found that hospital stays involving ICU services were 2.5 times more costly than other hospital stays.


title: Intensive care unit

text: Some hospitals have installed teleconferencing systems that allow doctors and nurses at a central facility (either in the same building, at a central location serving several local hospitals, or in rural locations another more urban facility) to collaborate with on-site staff and speak with patients (a form of telemedicine). This is variously called an "eICU", "virtual ICU", or "tele-ICU". Remote staff typically have access to vital signs from live monitoring systems, and telectronic health records so they may have access to a broader view of a patient's medical history. Often bedside and remote staff have met in person and may rotate responsibilities. Such systems are beneficial to intensive care units in order to ensure correct procedures are being followed for patients vulnerable to deterioration, to access vital signs remotely in order to keep patients that would have to be transferred to a larger facility if need be he/she may have demonstrated a significant decrease in stability.


title: Angioplasty

text: Angioplasty, is also known as balloon angioplasty and percutaneous transluminal angioplasty (PTA), is a minimally invasive endovascular procedure used to widen narrowed or obstructed arteries or veins, typically to treat arterial atherosclerosis. A deflated balloon attached to a catheter (a balloon catheter) is passed over a guide-wire into the narrowed vessel and then inflated to a fixed size. The balloon forces expansion of the blood vessel and the surrounding muscular wall, allowing an improved blood flow. A stent may be inserted at the time of ballooning to ensure the vessel remains open, and the balloon is then deflated and withdrawn. Angioplasty has come to include all manner of vascular interventions that are typically performed percutaneously.


title: Angioplasty

text: The word is composed of the combining forms of the Greek words ἀνγεῖον ' "vessel" or "cavity" (of the human body) and πλάσσω ' "form" or "mould".


title: Angioplasty

text: A coronary angioplasty is a therapeutic procedure to treat the stenotic (narrowed) coronary arteries of the heart found in coronary heart disease. These stenotic segments of the coronary arteries arise due to the buildup of cholesterol-laden plaques that form in a condition known as atherosclerosis. A percutaneous coronary intervention (PCI), or coronary angioplasty with stenting, is a non-surgical procedure used to improve the blood flow to the heart.


title: Angioplasty

text: Coronary angioplasty is indicated for coronary artery disease such as unstable angina, NSTEMI, STEMI and spontaneous coronary artery perforation. PCI for stable coronary disease has been shown to significantly relieve symptoms such as angina, or chest pain, thereby improving functional limitations and quality of life.


title: Angioplasty

text: Peripheral angioplasty refers to the use of a balloon to open a blood vessel outside the coronary arteries. It is most commonly done to treat atherosclerotic narrowings of the abdomen, leg and renal arteries caused by peripheral artery disease. Often, peripheral angioplasty is used in conjunction with guide wire, peripheral stenting and an atherectomy.


title: Angioplasty

text: Angioplasty can be used to treat advanced peripheral artery disease to relieve the claudication, or leg pain, that is classically associated with the condition.


title: Angioplasty

text: The bypass versus angioplasty in severe ischemia of the leg (BASIL) trial investigated infrainguinal bypass surgery first compared to angioplasty first in select patients with severe lower limb ischemia who were candidates for either procedure. The BASIL trial found that angioplasty was associated with less short term morbidity compared with bypass surgery, however long term outcomes favor bypass surgery.


title: Angioplasty

text: Based on the BASIL trial, the ACCF/AHA guidelines recommend balloon angioplasty only for patients with a life expectancy of 2 years or less or those who do not have an autogenous vein available. For patients with a life expectancy greater than 2 of years life, or who have an autogenous vein, a bypass surgery could be performed first.


title: Angioplasty

text: Renal artery stenosis is associated with hypertension and loss of renal function. Atherosclerotic obstruction of the renal artery can be treated with angioplasty with or without stenting of the renal artery. There is a weak recommendation for renal artery angioplasty in patients with renal artery stenosis and flash edema or congestive heart failure.


title: Angioplasty

text: Carotid artery stenosis can be treated with angioplasty and carotid stenting for patients at high risk for undergoing carotid endarterectomy (CEA). Although carotid endarterectomy is typically preferred over carotid artery stenting, stenting is indicated in select patients with radiation-induced stenosis or a carotid lesion not suitable for surgery.


title: Angioplasty

text: Angioplasty is used to treat venous stenosis affecting hemodialysis access, with drug-coated balloon angioplasty proving to have better 6 month and 12 month patency than conventional balloon angioplasty. Angioplasty is occasionally used to treat residual subclavian vein stenosis following thoracic outlet decompression surgery for thoracic outlet syndrome. There is a weak recommendation for deep venous stenting to treat obstructive chronic venous disease.


title: Angioplasty

text: Angioplasty requires an access vessel, typically the femoral or radial artery or femoral vein, to permit access to the vascular system for the wires and catheters used. If no access vessel of sufficient size and quality is available, angioplasty is contraindicated. A small vessel diameter, the presence of posterior calcification, occlusion, hematoma, or an earlier placement of a bypass origin, may make access to the vascular system too difficult.


title: Angioplasty

text: Percutaneous transluminal coronary angioplasty (PTCA) is contraindicated in patients with left main coronary artery disease, due to the risk of spasm of the left main coronary artery during the procedure. Also, PTCA is not recommended if there is less than 70% stenosis of the coronary arteries, as the stenosis it is not deemed to be hemodynamically significant below this level.


title: Angioplasty

text: Access to the vascular system is typically gained percutaneously (through the skin, without a large surgical incision). An introducer sheath is inserted into the blood vessel via the Seldinger technique. Fluoroscopic guidance uses magnetic resonance or X-ray fluoroscopy and radiopaque contrast dye to guide angled wires and catheters to the region of the body to be treated in real time. Tapered guidewire is chosen for small occlusion, followed by intermediate type guidewires for tortuous arteries and difficulty passing through extremely narrow channels, and stiff wires for hard, dense, and blunt occlusions. To treat a narrowing in a blood vessel, a wire is passed through the stenosis in the vessel and a balloon on a catheter is passed over the wire and into the desired position. The positioning is verified by fluoroscopy and the balloon is inflated using water mixed with contrast dye to 75 to 500 times normal blood pressure (6 to 20 atmospheres), with most coronary angioplasties requiring less than 10 atmospheres. A stent may or may not also be placed.


title: Angioplasty

text: At the conclusion of the procedure, the balloons, wires and catheters are removed and the vessel puncture site is treated either with direct pressure or a vascular closure device.


title: Angioplasty

text: Transradial artery access (TRA) and transfemoral artery access (TFA) are two techniques for percutaneous coronary intervention. TRA is the technique of choice for management of acute coronary syndrome (ACS) as it has significantly lower incidence of bleeding and vascular complications compared with the TFA approach. TRA also has a mortality benefit for high risk ACS patients and high risk bleeding patients. TRA was also found to yield improved quality of life, as well as decreased healthcare costs and resources.


title: Angioplasty

text: Relative to surgery, angioplasty is a lower-risk option for the treatment of the conditions for which it is used, but there are unique and potentially dangerous risks and complications associated with angioplasty:


title: Angioplasty

text: Angioplasty may also provide a less durable treatment for atherosclerosis and be more prone to restenosis relative to vascular bypass or coronary artery bypass grafting. Drug-eluting balloon angioplasty has significantly less restenosis, late lumen loss and target lesion revascularization at both short term and midterm follow-up compared to uncoated balloon angioplasty for femoropopliteal arterial occlusive disease. Although angioplasty of the femoropopliteal artery with paclitaxel-coated stents and balloons significantly reduces rates of vessel restenosis and target lesion revascularization, it was also found to have increased risk of death.


title: Angioplasty

text: After angioplasty, most patients are monitored overnight in the hospital, but if there are no complications, patients are sent home the following day.


title: Angioplasty

text: The catheter site is checked for bleeding and swelling and the heart rate and blood pressure are monitored to detect late rupture and hemorrhage. Post-procedure protocol also involves monitoring urinary output, cardiac symptoms, pain and other signs of systemic problems. Usually, patients receive medication that will relax them to protect the arteries against spasms. Patients are typically able to walk within two to six hours following the procedure and return to their normal routine by the following week.


title: Angioplasty

text: Angioplasty recovery consists of avoiding physical activity for several days after the procedure. Patients are advised to avoid heavy lifting and strenuous activities for a week. Patients will need to avoid physical stress or prolonged sport activities for a maximum of two weeks after a delicate balloon angioplasty.


title: Angioplasty

text: After the initial two week recovery phase, most angioplasty patients can begin to safely return to low-level exercise. A graduated exercise program is recommended whereby patients initially perform several short bouts of exercise each day, progressively increasing to one or two longer bouts of exercise. As a precaution, all structured exercise should be cleared by a cardiologist before commencing. Exercise-based rehabilitation following percutaneous coronary intervention has shown improvement in recurrent angina, total exercise time, ST-segment decline, and maximum exercise tolerance.


title: Angioplasty

text: Patients who experience swelling, bleeding or pain at the insertion site, develop fever, feel faint or weak, notice a change in temperature or color in the arm or leg that was used or have shortness of breath or chest pain should immediately seek medical advice.


title: Angioplasty

text: Patients with stents are usually prescribed dual antiplatelet therapy (DAPT) which consists of a P2Y12 inhibitor, such as clopidogrel, which is taken at the same time as acetylsalicylic acid (aspirin). Dual antiplatelet therapy (DAPT) is recommended for 1 month following bare metal stent placement, for 3 months following a second generation drug-eluting stent placement, and for 6–12 months following a first generation drug-eluting stent placement. DAPT's antiplatelet properties are intended to prevent blood clots, however they also increase the risk of bleeding, so it is important to consider each patient's preferences, cardiac conditions, and bleeding risk when determining the duration of DAPT treatment. Another important consideration is that concomitant use of Clopidogrel and Proton Pump Inhibitors following coronary angiography is associated with significantly higher adverse cardiovascular complications such as major adverse cardiovascular events (MACE), stent thrombosis and myocardial infarction.


title: Angioplasty

text: Angioplasty was first described by the US interventional radiologist Charles Dotter in 1964. Dr. Dotter pioneered modern medicine with the invention of angioplasty and the catheter-delivered stent, which were first used to treat peripheral arterial disease. On January 16, 1964, Dotter percutaneously dilated a tight, localized stenosis of the subsartorial artery in an 82-year-old woman with painful leg ischemia and gangrene who refused leg amputation. After successful dilation of the stenosis with a guide wire and coaxial Teflon catheters, the circulation returned to her leg. The dilated artery stayed open until her death from pneumonia two and a half years later. Charles Dotter is commonly known as the "Father of Interventional Radiology" and was nominated for the Nobel Prize in medicine in 1978.


title: Angioplasty

text: The first percutaneous coronary angioplasty on an awake patient was performed in Zurich by the German cardiologist Andreas Gruentzig on September 16, 1977.


title: Angioplasty

text: Dr. Simon H. Stertzer was the first to perform coronary angioplasty in the United States on March 1, 1978, at Lenox Hill Hospital in New York. That same day, Dr. Richard K. Myler of St. Mary's Hospital in San Francisco performed the second coronary angioplasty in the United States.


title: Angioplasty

text: The initial form of angioplasty was 'plain old balloon angioplasty' (POBA) without stenting, until the invention of bare metal stenting in the mid-1980s to prevent the early restenosis observed with POBA.


title: Angioplasty

text: Bare metal stents were found to cause in-stent restenosis as a result of neointimal hyperplasia and stent thrombosis, which led to the invention of drug-eluting stents with anti-proliferative drugs to combat in-stent restenosis.


title: Angioplasty

text: The first coronary angioplasty with a drug delivery stent system was performed by Dr. Stertzer and Dr. Luis de la Fuente, at the Instituto Argentino de Diagnóstico y Tratamiento (English: Argentina Institute of Diagnosis and Treatment) in Buenos Aires, in 1999.


title: Angioplasty

text: Ingemar Henry Lundquist invented the over-the-wire balloon catheter that is now used in the majority of angioplasty procedures in the world.


title: Nuclear magnetic resonance

text: Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are perturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electromagnetic signal with a frequency characteristic of the magnetic field at the nucleus. This process occurs near resonance, when the oscillation frequency matches the intrinsic frequency of the nuclei, which depends on the strength of the static magnetic field, the chemical environment, and the magnetic properties of the isotope involved; in practical applications with static magnetic fields up to ca. 20 tesla, the frequency is similar to VHF and UHF television broadcasts (60–1000 MHz). NMR results from specific magnetic properties of certain atomic nuclei. Nuclear magnetic resonance spectroscopy is widely used to determine the structure of organic molecules in solution and study molecular physics and crystals as well as non-crystalline materials. NMR is also routinely used in advanced medical imaging techniques, such as in magnetic resonance imaging (MRI).


title: Nuclear magnetic resonance

text: The most commonly used nuclei are and , although isotopes of many other elements, such as , can be studied by high-field NMR spectroscopy as well. In order to interact with the magnetic field in the spectrometer, the nucleus must have an intrinsic nuclear magnetic moment and angular momentum. This occurs when an isotope has a nonzero nuclear spin, meaning an odd number of protons and/or neutrons (see Isotope). Nuclides with even numbers of both have a total spin of zero and are therefore NMR-inactive.


title: Nuclear magnetic resonance

text: A key feature of NMR is that the resonant frequency of a particular sample substance is usually directly proportional to the strength of the applied magnetic field. It is this feature that is exploited in imaging techniques; if a sample is placed in a non-uniform magnetic field then the resonance frequencies of the sample's nuclei depend on where in the field they are located. Since the resolution of the imaging technique depends on the magnitude of the magnetic field gradient, many efforts are made to develop increased gradient field strength.


title: Nuclear magnetic resonance

text: The two magnetic fields are usually chosen to be perpendicular to each other as this maximizes the NMR signal strength. The frequencies of the time-signal response by the total magnetization (M) of the nuclear spins are analyzed in NMR spectroscopy and magnetic resonance imaging. Both use applied magnetic fields (B) of great strength, often produced by large currents in superconducting coils, in order to achieve dispersion of response frequencies and of very high homogeneity and stability in order to deliver spectral resolution, the details of which are described by chemical shifts, the Zeeman effect, and Knight shifts (in metals). The information provided by NMR can also be increased using hyperpolarization, and/or using two-dimensional, three-dimensional and higher-dimensional techniques.


title: Nuclear magnetic resonance

text: NMR phenomena are also utilized in low-field NMR, NMR spectroscopy and MRI in the Earth's magnetic field (referred to as Earth's field NMR), and in several types of magnetometers.


title: Nuclear magnetic resonance

text: Nuclear magnetic resonance was first described and measured in molecular beams by Isidor Rabi in 1938, by extending the Stern–Gerlach experiment, and in 1944, Rabi was awarded the Nobel Prize in Physics for this work. In 1946, Felix Bloch and Edward Mills Purcell expanded the technique for use on liquids and solids, for which they shared the Nobel Prize in Physics in 1952.


title: Nuclear magnetic resonance

text: Russell H. Varian filed the "Method and means for correlating nuclear properties of atoms and magnetic fields", on July 24, 1951. Varian Associates developed the first NMR unit called NMR HR-30 in 1952.


title: Nuclear magnetic resonance

text: Purcell had worked on the development of radar during World War II at the Massachusetts Institute of Technology's Radiation Laboratory. His work during that project on the production and detection of radio frequency power and on the absorption of such RF power by matter laid the foundation for his discovery of NMR in bulk matter.


title: Nuclear magnetic resonance

text: Rabi, Bloch, and Purcell observed that magnetic nuclei, like and , could absorb RF energy when placed in a magnetic field and when the RF was of a frequency specific to the identity of the nuclei. When this absorption occurs, the nucleus is described as being "in resonance". Different atomic nuclei within a molecule resonate at different (radio) frequencies for the same magnetic field strength. The observation of such magnetic resonance frequencies of the nuclei present in a molecule makes it possible to determine essential chemical and structural information about the molecule.


title: Nuclear magnetic resonance

text: The development of NMR as a technique in analytical chemistry and biochemistry parallels the development of electromagnetic technology and advanced electronics and their introduction into civilian use.


title: Nuclear magnetic resonance

text: In 2020s it was developed the zero- to ultralow-field nuclear magnetic resonance (ZULF NMR), a form of spectroscopy that provides abundant analytical results without the need for large magnetic fields. It is combined with a special technique that makes it possible to hyperpolarize atomic nuclei.


title: Nuclear magnetic resonance

text: All nucleons, that is neutrons and protons, composing any atomic nucleus, have the intrinsic quantum property of spin, an intrinsic angular momentum analogous to the classical angular momentum of a spinning sphere. The overall spin of the nucleus is determined by the spin quantum number "S". If the numbers of both the protons and neutrons in a given nuclide are even then , i.e. there is no overall spin. Then, just as electrons pair up in nondegenerate atomic orbitals, so do even numbers of protons or even numbers of neutrons (both of which are also spin-1/2 particles and hence fermions), giving zero overall spin.


title: Nuclear magnetic resonance

text: However, a proton and neutron spin vector that aligns itself opposite to the external magnetic field vector will have a lower energy when their spins are parallel, not anti-parallel. This parallel spin alignment of distinguishable particles does not violate the Pauli exclusion principle. The lowering of energy for parallel spins has to do with the quark structure of these two nucleons. As a result, the spin ground state for the deuteron (the nucleus of deuterium, the H isotope of hydrogen), which has only a proton and a neutron, corresponds to a spin value of 1, "not of zero". On the other hand, because of the Pauli exclusion principle, the tritium isotope of hydrogen must have a pair of anti-parallel spin neutrons (of total spin zero for the neutron-spin pair), plus a proton of spin . Therefore, the tritium total nuclear spin value is again , just like for the simpler, abundant hydrogen isotope, H nucleus (the "proton"). The NMR absorption frequency for tritium is also similar to that of H. In many other cases of "non-radioactive" nuclei, the overall spin is also non-zero. For example, the nucleus has an overall spin value .


title: Nuclear magnetic resonance

text: A non-zero spin formula_1 is always associated with a non-zero magnetic dipole moment, formula_2, via the relation formula_3 where "γ" is the gyromagnetic ratio. Classically, this corresponds to the proportionality between the angular momentum and the magnetic dipole moment of a spinning charged sphere, both of which are vectors parallel to the rotation axis whose length increases proportional to the spinning frequency. It is the magnetic moment and its interaction with magnetic fields that allows the observation of NMR signal associated with transitions between nuclear spin levels during resonant RF irradiation or caused by Larmor precession of the average magnetic moment after resonant irradiation. Nuclides with even numbers of both protons and neutrons have zero nuclear magnetic dipole moment and hence do not exhibit NMR signal. For instance, is an example of a nuclide that produces no NMR signal, whereas , , and are nuclides that do exhibit NMR spectra. The last two nuclei have spin "S" > 1/2 and are therefore quadrupolar nuclei.


title: Nuclear magnetic resonance

text: Electron spin resonance (ESR) is a related technique in which transitions between electronic rather than nuclear spin levels are detected. The basic principles are similar but the instrumentation, data analysis, and detailed theory are significantly different. Moreover, there is a much smaller number of molecules and materials with unpaired electron spins that exhibit ESR (or electron paramagnetic resonance (EPR)) absorption than those that have NMR absorption spectra. On the other hand, ESR has much higher signal per spin than NMR does.


title: Nuclear magnetic resonance

text: Nuclear spin is an intrinsic angular momentum that is quantized. This means that the magnitude of this angular momentum is quantized (i.e. "S" can only take on a restricted range of values), and also that the x, y, and z-components of the angular momentum are quantized, being restricted to integer or half-integer multiples of "ħ". The integer or half-integer quantum number associated with the spin component along the z-axis or the applied magnetic field is known as the magnetic quantum number, "m", and can take values from +"S" to −"S", in integer steps. Hence for any given nucleus, there are a total of angular momentum states.


title: Nuclear magnetic resonance

text: The "z"-component of the angular momentum vector (formula_1) is therefore , where "ħ" is the reduced Planck constant. The "z"-component of the magnetic moment is simply: formula_5


title: Nuclear magnetic resonance

text: Consider nuclei with a spin of one-half, like , or . Each nucleus has two linearly independent spin states, with "m" = or "m" = − (also referred to as spin-up and spin-down, or sometimes α and β spin states, respectively) for the z-component of spin. In the absence of a magnetic field, these states are degenerate; that is, they have the same energy. Hence the number of nuclei in these two states will be essentially equal at thermal equilibrium.


title: Nuclear magnetic resonance

text: If a nucleus is placed in a magnetic field, however, the two states no longer have the same energy as a result of the interaction between the nuclear magnetic dipole moment and the external magnetic field. The energy of a magnetic dipole moment formula_2 in a magnetic field B is given by: formula_7


title: Nuclear magnetic resonance

text: As a result, the different nuclear spin states have different energies in a non-zero magnetic field. In less formal language, we can talk about the two spin states of a spin as being "aligned" either with or against the magnetic field. If "γ" is positive (true for most isotopes used in NMR) then is the lower energy state.


title: Nuclear magnetic resonance

text: and this results in a small population bias favoring the lower energy state in thermal equilibrium. With more spins pointing up than down, a net spin magnetization along the magnetic field B results.


title: Nuclear magnetic resonance

text: A central concept in NMR is the precession of the spin magnetization around the magnetic field at the nucleus, with the angular frequency formula_11 where formula_12 relates to the oscillation frequency formula_13 and "B" is the magnitude of the field. This means that the spin magnetization, which is proportional to the sum of the spin vectors of nuclei in magnetically equivalent sites (the expectation value of the spin vector in quantum mechanics), moves on a cone around the B field. This is analogous to the precessional motion of the axis of a tilted spinning top around the gravitational field. In quantum mechanics, formula_14 is the "Bohr frequency" formula_15 of the formula_16 and formula_17 expectation values. Precession of non-equilibrium magnetization in the applied magnetic field B occurs with the Larmor frequency formula_18 without change in the populations of the energy levels because energy is constant (time-independent Hamiltonian).


title: Nuclear magnetic resonance

text: A perturbation of nuclear spin orientations from equilibrium will occur only when an oscillating magnetic field is applied whose frequency "ν" sufficiently closely matches the Larmor precession frequency "ν" of the nuclear magnetization. The populations of the spin-up and -down energy levels then undergo Rabi oscillations, which are analyzed most easily in terms of precession of the spin magnetization around the effective magnetic field in a reference frame rotating with the frequency "ν". The stronger the oscillating field, the faster the Rabi oscillations or the precession around the effective field in the rotating frame. After a certain time on the order of 2–1000 microseconds, a resonant RF pulse flips the spin magnetization to the transverse plane, i.e. it makes an angle of 90° with the constant magnetic field B ("90° pulse"), while after a twice longer time, the initial magnetization has been inverted ("180° pulse"). It is the transverse magnetization generated by a resonant oscillating field which is usually detected in NMR, during application of the relatively weak RF field in old-fashioned continuous-wave NMR, or after the relatively strong RF pulse in modern pulsed NMR.


title: Nuclear magnetic resonance

text: It might appear from the above that all nuclei of the same nuclide (and hence the same "γ") would resonate at exactly the same frequency. This is not the case. The most important perturbation of the NMR frequency for applications of NMR is the "shielding" effect of the surrounding shells of electrons. Electrons, similar to the nucleus, are also charged and rotate with a spin to produce a magnetic field opposite to the applied magnetic field. In general, this electronic shielding reduces the magnetic field "at the nucleus" (which is what determines the NMR frequency). As a result, the frequency required to achieve resonance is also reduced. This shift in the NMR frequency due to the electronic molecular orbital coupling to the external magnetic field is called chemical shift, and it explains why NMR is able to probe the chemical structure of molecules, which depends on the electron density distribution in the corresponding molecular orbitals. If a nucleus in a specific chemical group is shielded to a higher degree by a higher electron density of its surrounding molecular orbital, then its NMR frequency will be shifted "upfield" (that is, a lower chemical shift), whereas if it is less shielded by such surrounding electron density, then its NMR frequency will be shifted "downfield" (that is, a higher chemical shift).


title: Nuclear magnetic resonance

text: Unless the local symmetry of such molecular orbitals is very high (leading to "isotropic" shift), the shielding effect will depend on the orientation of the molecule with respect to the external field (B). In solid-state NMR spectroscopy, magic angle spinning is required to average out this orientation dependence in order to obtain frequency values at the average or isotropic chemical shifts. This is unnecessary in conventional NMR investigations of molecules in solution, since rapid "molecular tumbling" averages out the chemical shift anisotropy (CSA). In this case, the "average" chemical shift (ACS) or isotropic chemical shift is often simply referred to as the chemical shift.


title: Nuclear magnetic resonance

text: The process of population relaxation refers to nuclear spins that return to thermodynamic equilibrium in the magnet. This process is also called "T", "spin-lattice" or "longitudinal magnetic" relaxation, where "T" refers to the mean time for an individual nucleus to return to its thermal equilibrium state of the spins. After the nuclear spin population has relaxed, it can be probed again, since it is in the initial, equilibrium (mixed) state.


title: Nuclear magnetic resonance

text: The precessing nuclei can also fall out of alignment with each other and gradually stop producing a signal. This is called "T" or "transverse relaxation". Because of the difference in the actual relaxation mechanisms involved (for example, intermolecular versus intramolecular magnetic dipole-dipole interactions ), "T" is usually (except in rare cases) longer than "T" (that is, slower spin-lattice relaxation, for example because of smaller dipole-dipole interaction effects). In practice, the value of "T"* which is the actually observed decay time of the observed NMR signal, or free induction decay (to of the initial amplitude immediately after the resonant RF pulse), also depends on the static magnetic field inhomogeneity, which is quite significant. (There is also a smaller but significant contribution to the observed FID shortening from the RF inhomogeneity of the resonant pulse). In the corresponding FT-NMR spectrum—meaning the Fourier transform of the free induction decay—the "T"* time is inversely related to the width of the NMR signal in frequency units. Thus, a nucleus with a long "T" relaxation time gives rise to a very sharp NMR peak in the FT-NMR spectrum for a very homogeneous ("well-shimmed") static magnetic field, whereas nuclei with shorter "T" values give rise to broad FT-NMR peaks even when the magnet is shimmed well. Both "T" and "T" depend on the rate of molecular motions as well as the gyromagnetic ratios of both the resonating and their strongly interacting, next-neighbor nuclei that are not at resonance.


title: Nuclear magnetic resonance

text: A Hahn echo decay experiment can be used to measure the dephasing time, as shown in the animation. The size of the echo is recorded for different spacings of the two pulses. This reveals the decoherence that is not refocused by the 180° pulse. In simple cases, an exponential decay is measured which is described by the "T" time.


title: Nuclear magnetic resonance

text: NMR spectroscopy is one of the principal techniques used to obtain physical, chemical, electronic and structural information about molecules due to the chemical shift of the resonance frequencies of the nuclear spins in the sample. Peak splittings due to J- or dipolar couplings between nuclei are also useful. NMR spectroscopy can provide detailed and quantitative information on the functional groups, topology, dynamics and three-dimensional structure of molecules in solution and the solid state. Since the area under an NMR peak is usually proportional to the number of spins involved, peak integrals can be used to determine composition quantitatively.


title: Nuclear magnetic resonance

text: Structure and molecular dynamics can be studied (with or without "magic angle" spinning (MAS)) by NMR of quadrupolar nuclei (that is, with spin ) even in the presence of magnetic "dipole-dipole" interaction broadening (or simply, dipolar broadening), which is always much smaller than the quadrupolar interaction strength because it is a magnetic vs. an electric interaction effect.


title: Nuclear magnetic resonance

text: Additional structural and chemical information may be obtained by performing double-quantum NMR experiments for pairs of spins or quadrupolar nuclei such as . Furthermore, nuclear magnetic resonance is one of the techniques that has been used to design quantum automata, and also build elementary quantum computers.


title: Nuclear magnetic resonance

text: In the first few decades of nuclear magnetic resonance, spectrometers used a technique known as continuous-wave (CW) spectroscopy, where the transverse spin magnetization generated by a weak oscillating magnetic field is recorded as a function of the oscillation frequency or static field strength "B". When the oscillation frequency matches the nuclear resonance frequency, the transverse magnetization is maximized and a peak is observed in the spectrum. Although NMR spectra could be, and have been, obtained using a fixed constant magnetic field and sweeping the frequency of the oscillating magnetic field, it was more convenient to use a fixed frequency source and vary the current (and hence magnetic field) in an electromagnet to observe the resonant absorption signals. This is the origin of the counterintuitive, but still common, "high field" and "low field" terminology for low frequency and high frequency regions, respectively, of the NMR spectrum.


title: Nuclear magnetic resonance

text: As of 1996, CW instruments were still used for routine work because the older instruments were cheaper to maintain and operate, often operating at 60 MHz with correspondingly weaker (non-superconducting) electromagnets cooled with water rather than liquid helium. One radio coil operated continuously, sweeping through a range of frequencies, while another orthogonal coil, designed not to receive radiation from the transmitter, received signals from nuclei that reoriented in solution. As of 2014, low-end refurbished 60 MHz and 90 MHz systems were sold as FT-NMR instruments, and in 2010 the "average workhorse" NMR instrument was configured for 300 MHz.


title: Nuclear magnetic resonance

text: CW spectroscopy is inefficient in comparison with Fourier analysis techniques (see below) since it probes the NMR response at individual frequencies or field strengths in succession. Since the NMR signal is intrinsically weak, the observed spectrum suffers from a poor signal-to-noise ratio. This can be mitigated by signal averaging, i.e. adding the spectra from repeated measurements. While the NMR signal is the same in each scan and so adds linearly, the random noise adds more slowly – proportional to the square root of the number of spectra (see random walk). Hence the overall signal-to-noise ratio increases as the square-root of the number of spectra measured.


title: Nuclear magnetic resonance

text: Most applications of NMR involve full NMR spectra, that is, the intensity of the NMR signal as a function of frequency. Early attempts to acquire the NMR spectrum more efficiently than simple CW methods involved illuminating the target simultaneously with more than one frequency. A revolution in NMR occurred when short radio-frequency pulses began to be used, with a frequency centered at the middle of the NMR spectrum. In simple terms, a short pulse of a given "carrier" frequency "contains" a range of frequencies centered about the carrier frequency, with the range of excitation (bandwidth) being inversely proportional to the pulse duration, i.e. the Fourier transform of a short pulse contains contributions from all the frequencies in the neighborhood of the principal frequency. The restricted range of the NMR frequencies made it relatively easy to use short (1 - 100 microsecond) radio frequency pulses to excite the entire NMR spectrum.


title: Nuclear magnetic resonance

text: Applying such a pulse to a set of nuclear spins simultaneously excites all the single-quantum NMR transitions. In terms of the net magnetization vector, this corresponds to tilting the magnetization vector away from its equilibrium position (aligned along the external magnetic field). The out-of-equilibrium magnetization vector then precesses about the external magnetic field vector at the NMR frequency of the spins. This oscillating magnetization vector induces a voltage in a nearby pickup coil, creating an electrical signal oscillating at the NMR frequency. This signal is known as the free induction decay (FID), and it contains the sum of the NMR responses from all the excited spins. In order to obtain the frequency-domain NMR spectrum (NMR absorption intensity vs. NMR frequency) this time-domain signal (intensity vs. time) must be Fourier transformed. Fortunately, the development of Fourier transform (FT) NMR coincided with the development of digital computers and the digital fast Fourier transform (FFT). Fourier methods can be applied to many types of spectroscopy.


title: Nuclear magnetic resonance

text: Richard R. Ernst was one of the pioneers of pulsed NMR and won a Nobel Prize in chemistry in 1991 for his work on Fourier Transform NMR and his development of multi-dimensional NMR spectroscopy.