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Amok syndrome

Amok syndrome is an aggressive dissociative behavioral pattern derived from Indonesia and Malaysia that led to the English phrase running amok. The word derives from the Malay word amuk, traditionally meaning "rushing in a frenzy" or "attacking furiously". Amok syndrome presents as an episode of sudden mass assault against people or objects following a period of brooding, which has traditionally been regarded as occurring especially in Malaysian culture but is now increasingly viewed as psychopathological behavior. The syndrome of "Amok" is found in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV TR). In the DSM-V, Amok syndrome is no longer considered a culture-bound syndrome, since the category of culture-bound syndrome has been removed.

Malay word
The term amok originated from the Malay word meng-âmuk, which when roughly defined means "to make a furious and desperate charge". In turn, the word was derived from Proto-Malayo-Polynesian word hamuk, "attack". According to Malaysian and Indonesian cultures, amok is rooted in a deep spiritual belief. Malaysians traditionally believe that amok is caused by the hantu belian, which is an evil tiger spirit that enters one's body and causes the heinous act. As a result of the belief, those in Malay culture tolerate amok and deal with the after-effects with no ill will towards the assailant.

Although commonly used in a colloquial and less violent sense, the phrase is particularly associated with a specific sociopathic culture-bound syndrome in the cultures of Malaysia, Indonesia and Brunei. In a typical case of running amok, an individual (almost always male), having shown no previous sign of anger or any inclination to violence, will acquire a weapon (traditionally a sword or dagger, but possibly any of a variety of weapons) and in a sudden frenzy, will attempt to kill or seriously injure anyone he encounters and himself. Amok typically takes place in a well-populated or crowded area. Amok episodes of this kind normally end with the attacker being killed by bystanders or committing suicide, eliciting theories that amok may be a form of intentional suicide in cultures where suicide is heavily stigmatized. Those who do not commit suicide and are not killed typically lose consciousness, and upon regaining consciousness, claim amnesia.

An early Western claim of the practice appears in the journals of British explorer Captain James Cook, who purportedly encountered amok firsthand in 1770 during a voyage around the world. Cook writes of individuals behaving in a reckless, violent manner, without apparent cause and "indiscriminately killing and maiming villagers and animals in a frenzied attack."

A widely accepted explanation links amok with male honour (amok by women and children is virtually unknown). Running amok would thus be both a way of escaping the world (since perpetrators were normally killed or committed suicide) and re-establishing one's reputation as a man to be feared and respected.

Contemporary psychiatric syndrome
In 1849, Amok was officially classified as a psychiatric condition based on numerous reports and case studies that showed the majority of individuals who committed amok were, in some sense, mentally ill. "Running amok," is used to refer to the behavior of someone who, in the grip of strong emotion, obtains a weapon and begins attacking people. For about twenty years, this type of behavior has been described as a culture-bound syndrome. As of the DSM-V, the culture-bound syndrome category has been removed, meaning that this particular condition is no longer categorized as such. Culture-bound syndromes are seen as those conditions that only occur in certain societies whereas standard psychiatric diagnoses are not seen that way regardless if there is some sort of cultural limitation.

Recent research has revealed that Amok syndrome is not culture-specific but a syndrome that could happen anywhere around the world because anyone could experience an episode of Amok. Throughout history, mass murders have occurred in the United States, such as the Columbine High School massacre and the Sandy Hook Elementary School shooting, bringing into question if Amok syndrome is based on mental illness or the simple act of committing mass murder. Amok syndrome would, in turn, be more prevalent in other societies and not only in Malay cultures. In fact, there are other societies like Polynesia, such as "cafard," and Puerto Rico, "mal de pelea," that have similar syndromes with different terms.

Forms
Though the DSM-IV does not differentiate between them, observers historically described two forms of amok: beramok and amok. Beramok, considered to be more common, was associated with personal loss and preceded by a period of depression and brooding. Amok, the rarer form, was believed to stem from rage, perceived insult or a vendetta against a person.

Historical and cross-cultural comparisons
Early travelers in Asia sometimes describe a kind of military amok, in which soldiers apparently facing inevitable defeat suddenly burst into a frenzy of violence which so startled their enemies that it either delivered victory or at least ensured what the soldier in that culture considered an honourable death.

Tomé Pires in his Suma Oriental, observed the custom of the Javanese people in 1513: "There are among the nations no men who are amocos like those in the Javanese nation. Amocos means men who are determined to die (to run amuck). Some of them do it when they are drunk, and these are the common people; but the noblemen are much in the habit of challenging each other to duels, and they kill each other over their quarrels; and this is the custom of the country. Some of them kill themselves on horseback, and some of them on foot, according to what they have decided."Duarte Barbosa in 1514 recorded the Javanese people in Malacca: "They have very good arms and fight valiantly. There are some of them who if they fall ill of any severe illness, vow to God that if they remain in health they will of their own accord seek another more honourable death for his service, and as soon as they get well they take a dagger in their hands and go out into the streets and kill as many persons as they meet, both men, women and children, in such wise that they go like mad dogs, killing until they are killed. These are called amuco. And as soon as they see them begin this work, they cry out saying, amuco, amuco, in order that people may take care of themselves, and they kill them with dagger and spear thrusts. Many of these Javans live in this city with wives and children and property."

This form of amok appears to resemble the Scandinavian Berserker, mal de pelea (Puerto Rico), and iich'aa (Navaho). The Zulu battle trance is another example of the tendency of certain groups to work themselves up into a killing frenzy. In contemporary Indonesia, the term amok (amuk) generally refers not to individual violence, but to frenzied violence by mobs. Indonesians now commonly use the term 'gelap mata' (literally 'darkened eyes') to refer to individual amok. Laurens van der Post experienced the phenomenon in the East Indies and wrote in 1955:

"'Gelap mata', the Dark Eye, is an expression used in Sumatra and Java to describe a curious and disturbing social phenomenon. Socially speaking, the Malays, Sumatrans and Javanese are the best behaved people I have ever encountered. On the surface they are an extremely gentle, refined, submissive people. In fact the word 'Malay' comes from 'malu', 'gentle', and gentleness is a quality prized above all others among the Malays and their neighbours. In their family life, in their submission to traditional and parental authority, in their communal duties, they are among the most obedient people on earth. But every now and then something very disturbing happens. A man who has behaved in this obliging manner all his life and who has always done his duty by the outside world to perfection, suddenly finds it impossible to keep doing so. Overnight he revolts against goodness and dutifulness."

In the Philippines, amok also means unreasoning murderous rage by an individual. In 1876, the Spanish governor-general of the Philippines José Malcampo coined the term juramentado for the behavior (from juramentar – "to take an oath"), surviving into modern Philippine languages as huramentado. It has historically been linked with the Moro people of Mindanao, particularly in the Sulu Archipelago, in connection with societal and cultural pressures.

According to the Encyclopædia Britannica Eleventh Edition, some notable cases have occurred among the Rajputs. In 1634, the eldest son of the raja of Jodhpur ran amok at the court of Shah Jahan, failing in his attack on the emperor, but killing five of his officials. During the 18th century, again, at Hyderabad (Sind), two envoys, sent by the Jodhpur chief in regard to a quarrel between the two states, stabbed the prince and twenty-six of his suite before they themselves fell.

In popular culture
The Malaysian mythology surrounding hantu belian possessing humans and killing at random is a crucial plot point in The Night Tiger by Yangsze Choo.

title: Amok syndrome


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Apostles' Creed

The Apostles' Creed (Latin: Symbolum Apostolorum or Symbolum Apostolicum), sometimes titled the Apostolic Creed or the Symbol of the Apostles, is a Christian creed or "symbol of faith".

The creed most likely originated in 5th-century Gaul as a development of the Old Roman Symbol: the old Latin creed of the 4th century. It has been used in the Latin liturgical rites since the 8th century and, by extension, in the various modern branches of Western Christianity, including the modern liturgy and catechesis of the Catholic Church, Lutheranism, Anglicanism, Presbyterianism, Moravianism, Methodism, and Congregational churches. It is shorter than the full Niceno-Constantinopolitan Creed adopted in 381, but it is still explicitly trinitarian in structure, with sections affirming belief in God the Father, God the Son, and God the Holy Spirit. It does not address some Christological issues defined in the Nicene Creed. It thus says nothing explicitly about the divinity of either Jesus or the Holy Spirit. For this reason, it was held to predate the Nicene Creed in medieval Latin tradition.

The expression "Apostles' Creed" is first mentioned in a letter from the Synod of Milan dated AD 390, referring to a belief at the time that each of the Twelve Apostles contributed an article to the twelve articles of the creed.

History
The ecclesiastical use of Latin symbolum for creed—in the sense of "a distinctive mark of Christians", from the sense of Greek σύμβολον, a sign or token used for identification—first occurs around the middle of the 3rd century, in the correspondence of St. Cyprian and St. Firmilian, the latter in particular speaking of the trinitarian formula as the "Symbol of the Trinity", and recognizing it as an integral part of the rite of baptism. The term Symbolum Apostolicum appears for the first time in a letter, probably written by Ambrose, from a Council in Milan to Pope Siricius in about AD 390: "Let them give credit to the Symbol of the Apostles, which the Roman Church has always kept and preserved undefiled". Ambrose's term is here referring to the Old Roman Creed, the immediate predecessor of what is now known as the Apostles' Creed. The narrative of this creed having been jointly created by the Apostles, with each of the twelve contributing one of twelve articles, was already current at that time.

The Old Roman Creed had evolved from simpler texts based on Matthew 28:19, part of the Great Commission, and it has been argued that this earlier text was already in written form by the late 2nd century (c. 180).

The earliest known formula is found within Testamentum in Galilaca D[ominus]. N[oster]. I[esu]. Christi written between 150 and 180. This formula states: "[I believe] in the Father almighty, – and in Jesus Christ, our Savior; – and in the Holy Spirit, the Paraclete, in the holy Church, and in the remission of sins." As can be seen, it lacks the Christological part of the Old Roman Creed.

While the individual statements of belief that are included in the Apostles' Creed – even those not found in the Old Roman Symbol – are found in various writings by Irenaeus, Tertullian, Novatian, Marcellus, Rufinus, Ambrose, Augustine, Nicetas, and Eusebius Gallus, the earliest appearance of what we know as the Apostles' Creed was in the De singulis libris canonicis scarapsus (Excerpt from Individual Canonical Books) of St. Pirminius (Migne, Patrologia Latina 89, 1029 ff.), written between 710 and 714. Bettenson and Maunder state that it is first from Dicta Abbatis Pirminii de singulis libris canonicis scarapsus (idem quod excarpsus, excerpt), c. 750.

The text of what is now known as the Apostles' Creed was most likely developed in southern Gaul around the midpoint of the 5th century. A creed that is virtually identical to the current one is recorded by Faustus of Riez. It is possible that Faustus had the identical text, as the original text written by Faustus cannot be reconstructed with certainty. A version that is identical to the current one with the single exception of infera in place of inferos is recorded in the late 5th century. However, the Old Roman Creed remained the standard liturgical text of the Roman Church throughout the 4th to 7th centuries. It was replaced by the "Gallic" version of the Apostles' Creed only in the later 8th century, under Charlemagne, who imposed it throughout his dominions.

The phrase descendit ad inferos ('he descended into hell') is not found in the Nicene Creed. It echoes Ephesians 4:9, "κατέβη εἰς τὰ κατώτερα μέρη τῆς γῆς" (he descended into the lower earthly regions). This phrase first appeared in one of the two versions of Rufinus (d. 411), the Creed of Aquileia, and then did not appear again in any version of the creed until AD 650. Similarly, the references to the communion of saints is found neither in the Old Roman Symbol nor in the Nicene Creed. The reference to God as "creator of heaven and earth" likewise is not in the Nicene Creed of 325, but it is present in the extended version of the Nicene Creed (the Niceno-Constantinopolitan Creed) of 381.

The Eastern Orthodox Church does not use the Apostles' Creed, not because of an objection to any of its articles, but because of its omissions necessary for the definition of Nicene Christianity. The Orthodox delegates at the Council of Florence (1431–1449) explicitly challenged the western tradition that attributed the Apostles' Creed to the Twelve Apostles. This tradition was also shown to be historically untenable by Lorenzo Valla. The Roman Church does not state that text dates back to the Apostles themselves, the Roman catechism instead explaining that "the Apostles' Creed is so called because it is rightly considered to be a faithful summary of the apostles' faith."

Text
The following gives the original Latin text, with the traditional division into twelve articles, alongside an English translation. Underlined passages are those not present in the Old Roman Symbol as recorded by Tyrannius Rufinus.

There is also a received Greek text, which alongside the Latin is found in the Psalterium Græcum et Romanum, erroneously ascribed to Pope Gregory the Great. It was first edited by Archbishop Ussher in 1647, based on a manuscript preserved in the library of Corpus Christi College, Cambridge. The Latin text agrees with the "Creed of Pirminius" edited by Charles Abel Heurtley (De Fide Symbolo, 1900, p. 71). Four other Greek translations with slight variations were discovered by Carl Paul Caspari, and published in 1879 (Alte und neue Quellen zur Geschichte des Taufsymbols, vol. 3, pp. 11 sqq.).

The tradition of assigning each article to one of the apostles specifically can be traced to the 6th century. In Western sacral art, Credo Apostolorum refers to the figurative representation of the twelve apostles each alongside one of the articles. This artistic tradition extends from the high medieval to the Baroque period.

The precise division of the text and the sequence of attribution to the apostles has never been entirely fixed. For example, Pelbartus Ladislaus of Temesvár, writing in the late 15th century, divides article 5 in two but combines articles 11 and 12 into one, with the following attributions: 1. Peter,

2. John,

3. James, son of Zebedee,

4. Andrew,

5a. Philip,

5b. Thomas,

6. Bartholomew,

7. Matthew,

8. James, son of Alphaeus,

9. Simon the Zealot,

10. Jude Thaddaeus,

11–12. Matthias.

Liturgical use in Western Christianity
The Apostles' Creed is used in its direct form or in interrogative forms by Western Christian communities in several of their liturgical rites, in particular those of baptism and the Eucharist.

Rite of baptism
The Apostles' Creed, whose present form is similar to the baptismal creed used in Rome in the third and fourth centuries, actually developed from questions addressed to those seeking baptism. The Catholic Church still today uses an interrogative form of it in the Rite of Baptism (for both children and adults). In the official English translation (ICEL, 1974) the minister of baptism asks:

To each question, the catechumen, or, in the case of an infant, the parents and sponsor(s) (godparent(s)) in his or her place, answers "I do." Then the celebrant says: "This is our faith. This is the faith of the Church. We are proud to profess it, in Christ Jesus our Lord."

And all respond: Amen.

The Presbyterian Church of Aotearoa New Zealand uses the Apostles' Creed in its baptism rite in spite of the reservations of some of its members regarding the phrase "born of the virgin Mary".

The Episcopal Church in the United States of America uses the Apostles' Creed as part of a Baptismal Covenant for those who are to receive the Rite of Baptism. The Apostles' Creed is recited by candidates, sponsors and congregation, each section of the Creed being an answer to the celebrant's question, "Do you believe in God the Father (God the Son, God the Holy Spirit)?" It is also used in an interrogative form at the Easter Vigil in The Renewal of Baptismal Vows.

The Church of England likewise asks the candidates, sponsors and congregation to recite the Apostles' Creed in answer to similar interrogations, in which it avoids using the word God of the Son and the Holy Spirit, asking instead: "Do you believe and trust in his Son Jesus Christ?", and "Do you believe and trust in the Holy Spirit?" Moreover, "where there are strong pastoral reasons", it allows use of an alternative formula in which the interrogations, while speaking of "God the Son" and "God the Holy Spirit", are more elaborate but are not based on the Apostles' Creed, and the response in each case is: "I believe and trust in him." The Book of Common Prayer may also be used, which in its rite of baptism has the minister recite the Apostles' Creed in interrogative form. Asking the godparents or, in the case "of such as are of Riper Years", the candidate: "Dost thou believe in God the Father ..." The response is: "All this I stedfastly believe."

Lutherans following the Lutheran Service Book (Lutheran Church–Missouri Synod and the Lutheran Church–Canada), like Catholics and Anglicans, use the Apostles' Creed during the Sacrament of Baptism:

Following each question, the candidate answers: "Yes, I believe". If the candidates are unable to answer for themselves, the sponsors are to answer the questions.

For ELCA (Evangelical Lutheran Church in America) Lutherans who use the Evangelical Lutheran Worship book, the Apostles' Creed appears during the Sacrament of Holy Baptism Rite on p. 229 of the hardcover pew edition.

The United Methodist Church in the United States uses the Apostles' Creed as part of their baptismal rites in the form of an interrogatory addressed to the candidate(s) for baptism and the whole congregation as a way of professing the faith within the context of the Church's sacramental act. For infants, it is the professing of the faith by the parents, sponsors, and congregation on behalf of the candidate(s); for confirmands, it is the professing of the faith before and among the congregation. For the congregation, it is a reaffirmation of their professed faith.

Eucharistic rite
Since the 2002 edition, the Apostles' Creed is included in the Roman Missal as an alternative, with the indication, "Instead of the Niceno-Constantinopolitan Creed, especially during Lent and Easter time, the baptismal Symbol of the Roman Church, known as the Apostles' Creed, may be used." Previously the Nicene Creed was the only profession of faith that the Missal gave for use at Mass, except in Masses for children; but in some countries use of the Apostles' Creed was already permitted.

Canonical hours
The Apostles' Creed is used in Anglican services of Matins and Evening Prayer (Evensong). It is invoked after the recitation or singing of the Canticles, and is the only part of the services in which the congregation traditionally turns to face the altar, if they are seated transversely in the quire.

The Episcopal Church (United States) uses the Apostles' Creed in Morning Prayer and Evening Prayer.

Before the 1955 simplification of the rubrics of the Roman Breviary by Pope Pius XII, the Apostles' Creed was recited at the beginning of matins and prime, at the end of compline, and in some preces (a series of versicles and responses preceded by, eleison ("Lord, have mercy") and the Our Father) of prime and compline on certain days during Advent and Lent.

Indulgence
Recitation of the Apostles' Creed or the Nicene-Constantinopolitan Creed is required to obtain a partial indulgence.

International Consultation on English Texts
The International Consultation on English Texts (ICET), a first inter-church ecumenical group that undertook the writing of texts for use by English-speaking Christians in common, published Prayers We Have in Common (Fortress Press, 1970, 1971, 1975). Its version of the Apostles' Creed was adopted by several churches.

English Language Liturgical Consultation
The English Language Liturgical Consultation (ELLC), a successor body to the International Consultation on English Texts (ICET), published in 1988 a revised translation of the Apostles' Creed. It avoided the word his in relation to God and spoke of Jesus Christ as "God's only Son" instead of "his only Son". In the fourth line, it replaced the personal pronoun he with the relative who, and changed the punctuation, so as no longer to present the Creed as a series of separate statements. In the same line it removed the words the power of. It explained its rationale for making these changes and for preserving other controverted expressions in the 1988 publication Praying Together, with which it presented its new version:

Catholic Church
The initial (1970) English official translation of the Roman Missal of the Roman Catholic Church adopted the ICET version, as did catechetical texts such as the Catechism of the Catholic Church.

In 2008, the Catholic Church published a new English translation of the texts of the Mass of the Roman Rite, the use of which came into force at the end of 2011. It included the following translation of the Apostles' Creed:

Church of England
In the Church of England there are currently two authorized forms of the creed: that of the Book of Common Prayer (1662) and that of Common Worship (2000).

Book of Common Prayer, 1662 I believe in God the Father Almighty, Maker of heaven and earth:

And in Jesus Christ his only Son our Lord, Who was conceived by the Holy Ghost, Born of the Virgin Mary, Suffered under Pontius Pilate, Was crucified, dead, and buried: He descended into hell; The third day he rose again from the dead; He ascended into heaven, And sitteth on the right hand of God the Father Almighty; From thence he shall come to judge the quick and the dead.

I believe in the Holy Ghost; The holy Catholick Church; The Communion of Saints; The Forgiveness of sins; The Resurrection of the body, And the Life everlasting. Amen.

Common Worship I believe in God, the Father almighty, creator of heaven and earth.

I believe in Jesus Christ, his only Son, our Lord, who was conceived by the Holy Spirit, born of the Virgin Mary, suffered under Pontius Pilate, was crucified, died, and was buried; he descended to the dead. On the third day he rose again; he ascended into heaven, he is seated at the right hand of the Father, he will come to judge the living and the dead.

I believe in the Holy Spirit, the holy catholic Church, the communion of saints, the forgiveness of sins, the resurrection of the body, and the life everlasting. Amen.

Lutheran Church
In Luther's preface to his 'Small Catechism' which makes up part of the Book of Concord that contains the symbolical documents of the Lutheran Church, it is suggested to commit the Creed, along with the Decalogue and Lord's Prayer to memory.

Evangelical Lutheran Worship
The publication Evangelical Lutheran Worship published by Augsburg Fortress, is the primary worship resource for the Evangelical Lutheran Church in America, the largest Lutheran denomination in the United States, and the Evangelical Lutheran Church in Canada. It presents the official ELCA version, footnoting the phrase "he descended to the dead" to indicate an alternative reading: "or 'he descended into hell', another translation of this text in widespread use". Another alternative reading is "Christian church" instead of catholic since there is a Christian group called Catholics.

The text is as follows:

Church of Denmark
The Church of Denmark started using the phrase, from the baptismal vows "We renounce the devil and all his doings and all his beings" as the beginning of this creed, before the line "We believe in God etc." This is mostly due to the influence of the Danish pastor Grundtvig. See .

United Methodist Church
The United Methodists in the USA commonly incorporate the Apostles' Creed into their worship services. The version which is most often used is located at No. 881 in the United Methodist Hymnal, one of their most popular hymnals and one with a heritage to brothers John Wesley and Charles Wesley, founders of Methodism. It is notable for omitting the line "he descended into hell", but is otherwise very similar to the Book of Common Prayer version. The 1989 Hymnal has both the traditional version and the 1988 ecumenical version, which includes "he descended to the dead".

The Apostles' Creed as found in The Methodist Hymnal of 1939 also omits the line "he descended..." The Methodist Hymnal of 1966 has the same version of the creed, but with a note at the bottom of the page stating, "Traditional use of this creed includes these words: 'He descended into hell.

However, when the Methodist Episcopal Church was organized in the United States in 1784, John Wesley sent the new American Church a Sunday Service which included the phrase "he descended into hell" in the text of the Apostles' Creed. It is clear that Wesley intended American Methodists to use the phrase in the recitation of the Creed.

The United Methodist Hymnal of 1989 also contains (at #882) what it terms the "Ecumenical Version" of this creed which is the ecumenically accepted modern translation of the International Committee on English Texts (1975) as amended by the subsequent successor body, the English Language Liturgical Consultation (1987). This form of the Apostles' Creed can be found incorporated into the Eucharistic and Baptismal Liturgies in the Hymnal and in The United Methodist Book of Worship, and hence it is growing in popularity and use. The word catholic is intentionally left lowercase in the sense that the word catholic applies to the universal and ecumenical Christian church.

Musical settings
Musical settings of the Symbolum Apostolorum as a motet are rare. English composer Robert Wylkynson (d. ca. 1515) composed a thirteen-voice canon, Jesus autem transiens, included in the Eton Choirbook, which features the text of the Creed. The French composer Le Brung published one Latin setting in 1540, and the Spanish composer Fernando de las Infantas published two in 1578.

Martin Luther wrote the hymn "Wir glauben all an einen Gott" (translated into English as "We all believe in one God") in 1524 as a paraphrase of the Apostles' Creed.

In 1957, William P. Latham wrote "Credo (Metrical Version of the Apostle’s Creed)" in an SATB arrangement suitable for boys' and men's voices.

In 1979 John Michael Talbot, a Third Order Franciscan, composed and recorded "Creed" on his album, The Lord's Supper.

In 1986 Graham Kendrick published the popular "We believe in God the Father", closely based on the Apostles' Creed.

The song "Creed" on Petra's 1990 album Beyond Belief is loosely based on the Apostles' Creed.

GIA Publications published a hymn text in 1991 directly based on the Apostles' Creed, called "I Believe in God Almighty". It has been sung to hymn tunes from Wales, the Netherlands, and Ireland.

Rich Mullins and Beaker also composed a musical setting titled "Creed", released on Mullins' 1993 album A Liturgy, a Legacy, & a Ragamuffin Band. Notably, Mullins' version replaces "one holy catholic church" with "one holy church".

Integrity Music under the Hosanna! Music series, produced a live worship acoustic album in 1993, Be Magnified, which featured Randy Rothwell as worship leader, had an upbeat enthusiastic hymn called "The Apostle’s Creed", written by Randy Rothwell Burbank.

Newsboys released "We Believe" in 2013 on their album Restart. It was nominated for a Billboard Music Award for Top Christian Song.

In 2014 Hillsong released a version of the Apostles' Creed under the title "This I Believe (The Creed)" on their album No Other Name.

Keith & Kristyn Getty released an expression of the Apostles' Creed under the title "We Believe (Apostle's Creed)" on their 2016 album Facing a Task Unfinished.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Apostles' Creed


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Amicable numbers

Amicable numbers are two different natural numbers related in such a way that the sum of the proper divisors of each is equal to the other number. That is, s(a)=b and s(b)=a, where s(n)=σ(n)-n is equal to the sum of positive divisors of n except n itself (see also divisor function).

The smallest pair of amicable numbers is (220, 284). They are amicable because the proper divisors of 220 are 1, 2, 4, 5, 10, 11, 20, 22, 44, 55 and 110, of which the sum is 284; and the proper divisors of 284 are 1, 2, 4, 71 and 142, of which the sum is 220. (A proper divisor of a number is a positive factor of that number other than the number itself. For example, the proper divisors of 6 are 1, 2, and 3.)

The first ten amicable pairs are: (220, 284), (1184, 1210), (2620, 2924), (5020, 5564), (6232, 6368), (10744, 10856), (12285, 14595), (17296, 18416), (63020, 76084), and (66928, 66992). . (Also see and ) It is unknown if there are infinitely many pairs of amicable numbers.

A pair of amicable numbers constitutes an aliquot sequence of period 2. A related concept is that of a perfect number, which is a number that equals the sum of its own proper divisors, in other words a number which forms an aliquot sequence of period 1. Numbers that are members of an aliquot sequence with period greater than 2 are known as sociable numbers.

History
Amicable numbers were known to the Pythagoreans, who credited them with many mystical properties. A general formula by which some of these numbers could be derived was invented circa 850 by the Iraqi mathematician Thābit ibn Qurra (826–901). Other Arab mathematicians who studied amicable numbers are al-Majriti (died 1007), al-Baghdadi (980–1037), and al-Fārisī (1260–1320). The Iranian mathematician Muhammad Baqir Yazdi (16th century) discovered the pair (9363584, 9437056), though this has often been attributed to Descartes. Much of the work of Eastern mathematicians in this area has been forgotten.

Thābit ibn Qurra's formula was rediscovered by Fermat (1601–1665) and Descartes (1596–1650), to whom it is sometimes ascribed, and extended by Euler (1707–1783). It was extended further by Borho in 1972. Fermat and Descartes also rediscovered pairs of amicable numbers known to Arab mathematicians. Euler also discovered dozens of new pairs. The second smallest pair, (1184, 1210), was discovered in 1867 by 16-year-old B. Nicolò I. Paganini (not to be confused with the composer and violinist), having been overlooked by earlier mathematicians.

There are over 1,000,000,000 known amicable pairs.

Rules for generation
While these rules do generate some pairs of amicable numbers, many other pairs are known, so these rules are by no means comprehensive.

In particular, the two rules below produce only even amicable pairs, so they are of no interest for the open problem of finding amicable pairs coprime to 210 = 2·3·5·7, while over 1000 pairs coprime to 30 = 2·3·5 are known [García, Pedersen & te Riele (2003), Sándor & Crstici (2004)].

Thābit ibn Qurrah theorem
The Thābit ibn Qurrah theorem is a method for discovering amicable numbers invented in the 9th century by the Arab mathematician Thābit ibn Qurrah.

It states that if $$\begin{align} p &= 3 \times 2^{n-1} - 1, \\ q &= 3 \times 2^{n} - 1, \\ r &= 9 \times 2^{2n - 1} - 1, \end{align}$$

where $n > 1$ is an integer and $p, q, r$ are prime numbers, then $2^{n} × p × q$ and $2^{n} × r$ are a pair of amicable numbers. This formula gives the pairs $(220, 284)$ for $n = 2$, $(17296, 18416)$ for $n = 4$, and $(9363584, 9437056)$ for $n = 7$, but no other such pairs are known. Numbers of the form $3 × 2^{n} − 1$ are known as Thabit numbers. In order for Ibn Qurrah's formula to produce an amicable pair, two consecutive Thabit numbers must be prime; this severely restricts the possible values of $n$.

To establish the theorem, Thâbit ibn Qurra proved nine lemmas divided into two groups. The first three lemmas deal with the determination of the aliquot parts of a natural integer. The second group of lemmas deals more specifically with the formation of perfect, abundant and deficient numbers.

Euler's rule
Euler's rule is a generalization of the Thâbit ibn Qurra theorem. It states that if $$\begin{align} p &= (2^{n-m} + 1) \times 2^m - 1, \\ q &= (2^{n-m} + 1) \times 2^n - 1, \\ r &= (2^{n-m} + 1)^2 \times 2^{m+n} - 1, \end{align}$$ where $n > m > 0$ are integers and $p, q, r$ are prime numbers, then $2^{n} × p × q$ and $2^{n} × r$ are a pair of amicable numbers. Thābit ibn Qurra's theorem corresponds to the case $m = n − 1$. Euler's rule creates additional amicable pairs for $(m,n) = (1,8), (29,40)$ with no others being known. Euler (1747 & 1750) overall found 58 new pairs increasing the number of pairs that were then known to 61.

Regular pairs
Let ($m$, $n$) be a pair of amicable numbers with $m < n$, and write $m = gM$ and $n = gN$ where $g$ is the greatest common divisor of $m$ and $n$. If $M$ and $N$ are both coprime to $g$ and square free then the pair ($m$, $n$) is said to be regular ; otherwise, it is called irregular or exotic. If ($m$, $n$) is regular and $M$ and $N$ have $i$ and $j$ prime factors respectively, then $(m, n)$ is said to be of type $(i, j)$.

For example, with $(m, n) = (220, 284)$, the greatest common divisor is $4$ and so $M = 55$ and $N = 71$. Therefore, $(220, 284)$ is regular of type $(2, 1)$.

Twin amicable pairs
An amicable pair $(m, n)$ is twin if there are no integers between $m$ and $n$ belonging to any other amicable pair.

Other results
In every known case, the numbers of a pair are either both even or both odd. It is not known whether an even-odd pair of amicable numbers exists, but if it does, the even number must either be a square number or twice one, and the odd number must be a square number. However, amicable numbers where the two members have different smallest prime factors do exist: there are seven such pairs known. Also, every known pair shares at least one common prime factor. It is not known whether a pair of coprime amicable numbers exists, though if any does, the product of the two must be greater than 1065. Also, a pair of coprime amicable numbers cannot be generated by Thabit's formula (above), nor by any similar formula.

In 1955, Paul Erdős showed that the density of amicable numbers, relative to the positive integers, was 0.

In 1968, Martin Gardner noted that most even amicable pairs known at his time have sums divisible by 9, and a rule for characterizing the exceptions was obtained.

According to the sum of amicable pairs conjecture, as the number of the amicable numbers approaches infinity, the percentage of the sums of the amicable pairs divisible by ten approaches 100%. Although all amicable pairs up to 10,000 are even pairs, the proportion of odd amicable pairs increases steadily towards higher numbers, and presumably there are more of them than of even amicable pairs (A360054 in OEIS).

Gaussian amicable pairs exist.

Amicable tuples
Amicable numbers $$(m, n)$$ satisfy $$\sigma(m)-m=n$$ and $$\sigma(n)-n=m$$ which can be written together as $$\sigma(m)=\sigma(n)=m+n$$. This can be generalized to larger tuples, say $$(n_1,n_2,\ldots,n_k)$$, where we require

 * $$\sigma(n_1)=\sigma(n_2)= \dots =\sigma(n_k) = n_1+n_2+ \dots +n_k$$

For example, (1980, 2016, 2556) is an amicable triple, and (3270960, 3361680, 3461040, 3834000) is an amicable quadruple.

Amicable multisets are defined analogously and generalizes this a bit further.

Sociable numbers
Sociable numbers are the numbers in cyclic lists of numbers (with a length greater than 2) where each number is the sum of the proper divisors of the preceding number. For example, $$1264460 \mapsto 1547860 \mapsto 1727636 \mapsto 1305184 \mapsto 1264460 \mapsto\dots$$ are sociable numbers of order 4.

Searching for sociable numbers
The aliquot sequence can be represented as a directed graph, $$G_{n,s}$$, for a given integer $$n$$, where $$s(k)$$ denotes the sum of the proper divisors of $$k$$. Cycles in $$G_{n,s}$$ represent sociable numbers within the interval $$[1,n]$$. Two special cases are loops that represent perfect numbers and cycles of length two that represent amicable pairs.

References in popular culture

 * Amicable numbers are featured in the novel The Housekeeper and the Professor by Yōko Ogawa, and in the Japanese film based on it.
 * Paul Auster's collection of short stories entitled True Tales of American Life contains a story ('Mathematical Aphrodisiac' by Alex Galt) in which amicable numbers play an important role.
 * Amicable numbers are featured briefly in the novel The Stranger House by Reginald Hill.
 * Amicable numbers are mentioned in the French novel The Parrot's Theorem by Denis Guedj.
 * Amicable numbers are mentioned in the JRPG Persona 4 Golden.
 * Amicable numbers are featured in the visual novel Rewrite.
 * Amicable numbers (220, 284) are referenced in episode 13 of the 2017 Korean drama Andante.
 * Amicable numbers are featured in the Greek movie The Other Me (2016 film).
 * Amicable numbers are discussed in the book Are Numbers Real? by Brian Clegg.
 * Amicable numbers are mentioned in the 2020 novel Apeirogon by Colum McCann.

title: Amicable numbers


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Agar

Agar ( or ), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from "ogonori" (Gracilaria) and "tengusa" (Gelidiaceae). As found in nature, agar is a mixture of two components, the linear polysaccharide agarose and a heterogeneous mixture of smaller molecules called agaropectin. It forms the supporting structure in the cell walls of certain species of algae and is released on boiling. These algae are known as agarophytes, belonging to the Rhodophyta (red algae) phylum. The processing of food-grade agar removes the agaropectin, and the commercial product is essentially pure agarose.

Agar has been used as an ingredient in desserts throughout Asia and also as a solid substrate to contain culture media for microbiological work. Agar can be used as a laxative; an appetite suppressant; a vegan substitute for gelatin; a thickener for soups; in fruit preserves, ice cream, and other desserts; as a clarifying agent in brewing; and for sizing paper and fabrics.

Etymology
The word agar comes from agar-agar, the Malay name for red algae (Gigartina, Eucheuma, Gracilaria) from which the jelly is produced. It is also known as Kanten (寒天) (from the phrase kan-zarashi tokoroten (寒曬心太) or "cold-exposed agar"), Japanese isinglass, China grass, Ceylon moss or Jaffna moss. Gracilaria edulis or its synonym G. lichenoides is specifically referred to as agal-agal or Ceylon agar.

History
Macroalgae have been used widely as food by coastal cultures, especially in Southeast Asia. In the Philippines, Gracilaria, known as gulaman (also guraman, gar-garao, or gulaman dagat, among other names) in Tagalog, have been harvested and used as food for centuries, eaten both fresh or sun-dried and turned into jellies. The earliest historical attestation is from the Vocabulario de la lengua tagala (1754) by the Jesuit priests Juan de Noceda and Pedro de Sanlucar, where golaman or gulaman was defined as "una yerva, de que se haze conserva a modo de Halea, naze en la mar" ("a herb, from which a jam-like preserve is made, grows in the sea"), with an additional entry for guinolaman to refer to food made with the jelly.

Carrageenan, derived from gusô (Eucheuma spp.), which also congeals into a gel-like texture is also used similarly among the Visayan peoples and have been recorded in the even earlier Diccionario De La Lengua Bisaya, Hiligueina y Haraia de la isla de Panay y Sugbu y para las demas islas (c.1637) of the Augustinian missionary Alonso de Méntrida. In the book, Méntrida describes gusô as being cooked until it melts, and then allowed to congeal into a sour dish.

In Ambon Island in the Maluku Islands of Indonesia, agar is extracted from Graciliaria and eaten as a type of pickle or a sauce. Jelly seaweeds were also favoured and foraged by Malay communities living on the coasts of the Riau Archipelago and Singapore in Southeast Asia for centuries. 19th century records indicate that dried Graciliaria were one of the bulk exports of British Malaya to China. Poultices made from agar were also used for swollen knee joints and sores in Johore and Singapore.

The application of agar as a food additive in Japan is alleged to have been discovered in 1658 by Mino Tarōzaemon, an innkeeper in current Fushimi-ku, Kyoto who, according to legend, was said to have discarded surplus seaweed soup (Tokoroten) and noticed that it gelled later after a winter night's freezing.

Agar was first subjected to chemical analysis in 1859 by the French chemist Anselme Payen, who had obtained agar from the marine algae Gelidium corneum.

Beginning in the late 19th century, agar began to be used as a solid medium for growing various microbes. Agar was first described for use in microbiology in 1882 by the German microbiologist Walther Hesse, an assistant working in Robert Koch's laboratory, on the suggestion of his wife Fanny Hesse. Agar quickly supplanted gelatin as the base of microbiological media, due to its higher melting temperature, allowing microbes to be grown at higher temperatures without the media liquefying.

With its newfound use in microbiology, agar production quickly increased. This production centered on Japan, which produced most of the world's agar until World War II. However, with the outbreak of World War II, many nations were forced to establish domestic agar industries in order to continue microbiological research. Around the time of World War II, approximately 2,500 tons of agar were produced annually. By the mid-1970s, production worldwide had increased dramatically to approximately 10,000 tons each year. Since then, production of agar has fluctuated due to unstable and sometimes over-utilized seaweed populations.

Chemical composition
Agar consists of a mixture of two polysaccharides: agarose and agaropectin, with agarose making up about 70% of the mixture, while agaropectin makes about 30% of it. Agarose is a linear polymer, made up of repeating units of agarobiose, a disaccharide made up of D-galactose and 3,6-anhydro-L-galactopyranose. Agaropectin is a heterogeneous mixture of smaller molecules that occur in lesser amounts, and is made up of alternating units of D-galactose and L-galactose heavily modified with acidic side-groups, such as sulfate, glucuronate, and pyruvate.

Physical properties
Agar exhibits a phenomenon known as hysteresis whereby, when mixed with water, it solidifies and forms a gel below about 32–42 C, which is called the gel point, and melts above 85 C, which is the melting point. Hysteresis is the property of having a difference between the gel point and melting point temperatures. This property lends a suitable balance between easy melting and good gel stability at relatively high temperatures. Since many scientific applications require incubation at temperatures close to human body temperature (37 °C), agar is more appropriate than other solidifying agents that melt at this temperature, such as gelatin.

Culinary
Agar-agar is a natural vegetable gelatin counterpart. It is white and semi-translucent when sold in packages as washed and dried strips or in powdered form. It can be used to make jellies, puddings, and custards. When making jelly, it is boiled in water until the solids dissolve. Sweetener, flavoring, coloring, fruits and or vegetables are then added, and the liquid is poured into molds to be served as desserts and vegetable aspics or incorporated with other desserts such as a layer of jelly in a cake.

Agar-agar is approximately 80% dietary fiber, so it can serve as an intestinal regulator. Its bulking quality has been behind fad diets in Asia, for example the kanten (the Japanese word for agar-agar ) diet. Once ingested, kanten triples in size and absorbs water. This results in the consumers feeling fuller.

Asian culinary
One use of agar in Japanese cuisine is in anmitsu, a dessert made of small cubes of agar jelly and served in a bowl with various fruits or other ingredients. It is also the main ingredient in mizu yōkan, another popular Japanese food. In Philippine cuisine, it is used to make the jelly bars in the various gulaman refreshments like sago't gulaman, samalamig, or desserts such as buko pandan, agar flan, halo-halo, fruit cocktail jelly, and the black and red gulaman used in various fruit salads. In Vietnamese cuisine, jellies made of flavored layers of agar-agar, called thạch, are a popular dessert, and are often made in ornate molds for special occasions. In Indian cuisine, agar is used for making desserts. In Burmese cuisine, a sweet jelly known as kyauk kyaw is made from agar. Agar jelly is widely used in Taiwanese bubble tea.

Other culinary
It can be used as addition to or as a replacement for pectin in jams and marmalades, as a substitute to gelatin for its superior gelling properties, and as a strengthening ingredient in souffles and custards. Another use of agar-agar is in a Russian dish ptich'ye moloko (bird's milk), a rich jellified custard (or soft meringue) used as a cake filling or chocolate-glazed as individual sweets.

Agar-agar may also be used as the gelling agent in gel clarification, a culinary technique used to clarify stocks, sauces, and other liquids. Mexico has traditional candies made out of Agar gelatin, most of them in colorful, half-circle shapes that resemble a melon or watermelon fruit slice, and commonly covered with sugar. They are known in Spanish as Dulce de Agar (Agar sweets)

Agar-agar is an allowed nonorganic/nonsynthetic additive used as a thickener, gelling agent, texturizer, moisturizer, emulsifier, flavor enhancer, and absorbent in certified organic foods.

Agar plate

An agar plate or Petri dish is used to provide a growth medium using a mix of agar and other nutrients in which microorganisms, including bacteria and fungi, can be cultured and observed under the microscope. Agar is indigestible for many organisms so that microbial growth does not affect the gel used and it remains stable. Agar is typically sold commercially as a powder that can be mixed with water and prepared similarly to gelatin before use as a growth medium. Nutrients are typically added to meet the nutritional needs of the microbes organism, the formulations of which may be "undefined" where the precise composition is unknown, or "defined" where the exact chemical composition is known. Agar is often dispensed using a sterile media dispenser.

Different algae produce various types of agar. Each agar has unique properties that suit different purposes. Because of the agarose component, the agar solidifies. When heated, agarose has the potential to melt and then solidify. Because of this property, they are referred to as "physical gels". In contrast, polyacrylamide polymerization is an irreversible process, and the resulting products are known as chemical gels.

There are a variety of different types of agar that support the growth of different microorganisms. A nutrient agar may be permissive, allowing for the cultivation of any non-fastidious microorganisms; a commonly-used nutrient agar for bacteria is the Luria Bertani (LB) agar which contains lysogeny broth, a nutrient-rich medium used for bacterial growth. Additionally, 2216 Marine Broth (MB) agar, with high salt content, is optimized for growing heterotrophic marine bacteria like those of the Vibrio genus, while Terrific Broth (TB) agar is used to non-selectively culture high yields of the bacterium E. coli. More generally, enriched media is an agar variety that is infused with the necessary nutrients required by fastidious organisms to grow. Despite the large diversity of agar mediums, yeast extract is a common ingredient across all varieties as it is a macronutrient that provides a nitrogen source for all bacterial cell types. Other fastidious organisms may require the addition of different biological fluids such as horse or sheep blood, serum, egg yolk, and so on. Agar plates can also be selective, and can be used to promote the growth of bacteria of interest while inhibiting others. A variety of chemicals may be added to create an environment favourable for specific types of bacteria or bacteria with certain properties, but not conducive for growth of others. For example, antibiotics may be added in cloning experiments whereby bacteria with antibiotic-resistant plasmid are selected. In addition to antibiotic treated agar, other selective and indicator agar plates include TCBS agar and MacConkey agar. Thiosulfate citrate bile salts sucrose (TCBS) agar is used to differentiate Vibrio species based on their sucrose metabolism, since only some will metabolize the sucrose in the plate and change its pH. Indicator dyes included in the gel will display a visual change of the pH by changing the gel color from green to yellow. MacConkey agar contains bile salts and crystal violet to selectively grow gram-negative bacteria and differentiate between species using pH-indicator dyes that demonstrate lactose metabolism properties.

Motility assays
As a gel, an agar or agarose medium is porous and therefore can be used to measure microorganism motility and mobility. The gel's porosity is directly related to the concentration of agarose in the medium, so various levels of effective viscosity (from the cell's "point of view") can be selected, depending on the experimental objectives.

A common identification assay involves culturing a sample of the organism deep within a block of nutrient agar. Cells will attempt to grow within the gel structure. Motile species will be able to migrate, albeit slowly, throughout the gel, and infiltration rates can then be visualized, whereas non-motile species will show growth only along the now-empty path introduced by the invasive initial sample deposition.

Another setup commonly used for measuring chemotaxis and chemokinesis utilizes the under-agarose cell migration assay, whereby a layer of agarose gel is placed between a cell population and a chemoattractant. As a concentration gradient develops from the diffusion of the chemoattractant into the gel, various cell populations requiring different stimulation levels to migrate can then be visualized over time using microphotography as they tunnel upward through the gel against gravity along the gradient.

Plant biology

Research grade agar is used extensively in plant biology as it is optionally supplemented with a nutrient and/or vitamin mixture that allows for seedling germination in Petri dishes under sterile conditions (given that the seeds are sterilized as well). Nutrient and/or vitamin supplementation for Arabidopsis thaliana is standard across most experimental conditions. Murashige & Skoog (MS) nutrient mix and Gamborg's B5 vitamin mix in general are used. A 1.0% agar/0.44% MS+vitamin dH2O solution is suitable for growth media between normal growth temps.

When using agar, within any growth medium, it is important to know that the solidification of the agar is pH-dependent. The optimal range for solidification is between 5.4 and 5.7. Usually, the application of potassium hydroxide is needed to increase the pH to this range. A general guideline is about 600 μl 0.1M KOH per 250 ml GM. This entire mixture can be sterilized using the liquid cycle of an autoclave.

This medium nicely lends itself to the application of specific concentrations of phytohormones etc. to induce specific growth patterns in that one can easily prepare a solution containing the desired amount of hormone, add it to the known volume of GM, and autoclave to both sterilize and evaporate off any solvent that may have been used to dissolve the often-polar hormones. This hormone/GM solution can be spread across the surface of Petri dishes sown with germinated and/or etiolated seedlings.

Experiments with the moss Physcomitrella patens, however, have shown that choice of the gelling agent – agar or Gelrite – does influence phytohormone sensitivity of the plant cell culture.

Other uses
Agar is used: Gelidium agar is used primarily for bacteriological plates. Gracilaria agar is used mainly in food applications.
 * As an impression material in dentistry.
 * As a medium to precisely orient the tissue specimen and secure it by agar pre-embedding (especially useful for small endoscopy biopsy specimens) for histopathology processing
 * To make salt bridges and gel plugs for use in electrochemistry.
 * In formicariums as a transparent substitute for sand and a source of nutrition.
 * As a natural ingredient in forming modeling clay for young children to play with.
 * As an allowed biofertilizer component in organic farming.
 * As a substrate for precipitin reactions in immunology.
 * At different times as a substitute for gelatin in photographic emulsions, arrowroot in preparing silver paper and as a substitute for fish glue in resist etching.
 * As an MRI elastic gel phantom to mimic tissue mechanical properties in Magnetic Resonance Elastography

In 2016, AMAM, a Japanese company, developed a prototype for Agar-based commercial packaging system called Agar Plasticity, intended as a replacement for oil-based plastic packaging.

title: Agar


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Acid rain

Acid rain is rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). Most water, including drinking water, has a neutral pH that exists between 6.5 and 8.5, but acid rain has a pH level lower than this and ranges from 4–5 on average. The more acidic the acid rain is, the lower its pH is. Acid rain can have harmful effects on plants, aquatic animals, and infrastructure. Acid rain is caused by emissions of sulfur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids.

Acid rain has been shown to have adverse impacts on forests, freshwaters, soils, microbes, insects and aquatic life-forms. In ecosystems, persistent acid rain reduces tree bark durability, leaving flora more susceptible to environmental stressors such as drought, heat/cold and pest infestation. Acid rain is also capable of detrimenting soil composition by stripping it of nutrients such as calcium and magnesium which play a role in plant growth and maintaining healthy soil. In terms of human infrastructure, acid rain also causes paint to peel, corrosion of steel structures such as bridges, and weathering of stone buildings and statues as well as having impacts on human health.

Some governments, including those in Europe and North America, have made efforts since the 1970s to reduce the release of sulfur dioxide and nitrogen oxide into the atmosphere through air pollution regulations. These efforts have had positive results due to the widespread research on acid rain starting in the 1960s and the publicized information on its harmful effects. The main source of sulfur and nitrogen compounds that result in acid rain are anthropogenic, but nitrogen oxides can also be produced naturally by lightning strikes and sulfur dioxide is produced by volcanic eruptions.

Definition
"Acid rain" is a popular term referring to the deposition of a mixture from wet (rain, snow, sleet, fog, cloudwater, and dew) and dry (acidifying particles and gases) acidic components. Distilled water, once carbon dioxide is removed, has a neutral pH of 7. Liquids with a pH less than 7 are acidic, and those with a pH greater than 7 are alkaline. "Clean" or unpolluted rain has an acidic pH, but usually no lower than 5.7, because carbon dioxide and water in the air react together to form carbonic acid, a weak acid according to the following reaction:

 * H2O (l) + CO2 (g) <-> H2CO3 (aq)

Carbonic acid then can ionize in water forming low concentrations of carbonate and hydronium ions:

 * H2O (l) + H2CO3 (aq) <-> HCO3− (aq) + H3O+ (aq)

Unpolluted rain can also contain other chemicals which affect its pH (acidity level). A common example is nitric acid produced by electric discharge in the atmosphere such as lightning. Acid deposition as an environmental issue (discussed later in the article) would include additional acids other than H2CO3.

Occasional pH readings in rain and fog water of well below 2.4 have been reported in industrialized areas.

The main sources of the SO2 and NOx pollution that causes acid rain are burning fossil fuels to generate electricity and power internal combustion vehicles, to refine oil, and in industrial manufacturing and other processes.

History
Acid rain was first systematically studied in Europe, in the 1960s, and in the United States and Canada, the following decade.

In Europe
The corrosive effect of polluted, acidic city air on limestone and marble was noted in the 17th century by John Evelyn, who remarked upon the poor condition of the Arundel marbles. Since the Industrial Revolution, emissions of sulfur dioxide and nitrogen oxides into the atmosphere have increased. In 1852, Robert Angus Smith was the first to show the relationship between acid rain and atmospheric pollution in Manchester, England. Smith coined the term "acid rain" in 1872.

In the late 1960s, scientists began widely observing and studying the phenomenon. At first, the main focus in this research lay on local effects of acid rain. Waldemar Christofer Brøgger was the first to acknowledge long-distance transportation of pollutants crossing borders from the United Kingdom to Norway – a problem systematically studied by Brynjulf Ottar in the 1970s. Ottar's work was strongly influenced by Swedish soil scientist Svante Odén, who had drawn widespread attention to Europe's acid rain problem in popular newspapers and wrote a landmark paper on the subject in 1968.

In the United States

The earliest report about acid rain in the United States came from chemical evidence gathered from Hubbard Brook Valley; public awareness of acid rain in the US increased in the 1970s after The New York Times reported on these findings.

In 1972, a group of scientists, including Gene Likens, discovered the rain that was deposited at White Mountains of New Hampshire was acidic. The pH of the sample was measured to be 4.03 at Hubbard Brook. The Hubbard Brook Ecosystem Study followed up with a series of research studies that analyzed the environmental effects of acid rain. The alumina from soils neutralized acid rain that mixed with stream water at Hubbard Brook. The result of this research indicated that the chemical reaction between acid rain and aluminium leads to an increasing rate of soil weathering. Experimental research examined the effects of increased acidity in streams on ecological species. In 1980, scientists modified the acidity of Norris Brook, New Hampshire, and observed the change in species' behaviors. There was a decrease in species diversity, an increase in community dominants, and a reduction in the food web complexity.

In 1980, the US Congress passed an Acid Deposition Act. This Act established an 18-year assessment and research program under the direction of the National Acidic Precipitation Assessment Program (NAPAP). NAPAP enlarged a network of monitoring sites to determine how acidic precipitation was, seeking to determine long-term trends, and established a network for dry deposition. Using a statistically based sampling design, NAPAP quantified the effects of acid rain on a regional basis by targeting research and surveys to identify and quantify the impact of acid precipitation on freshwater and terrestrial ecosystems. NAPAP also assessed the effects of acid rain on historical buildings, monuments, and building materials. It also funded extensive studies on atmospheric processes and potential control programs.

From the start, policy advocates from all sides attempted to influence NAPAP activities to support their particular policy advocacy efforts, or to disparage those of their opponents. For the US Government's scientific enterprise, a significant impact of NAPAP were lessons learned in the assessment process and in environmental research management to a relatively large group of scientists, program managers, and the public.

In 1981, the National Academy of Sciences was looking into research about the controversial issues regarding acid rain. President Ronald Reagan dismissed the issues of acid rain until his personal visit to Canada and confirmed that the Canadian border suffered from the drifting pollution from smokestacks originating in the US Midwest. Reagan honored the agreement to Canadian Prime Minister Pierre Trudeau's enforcement of anti-pollution regulation. In 1982, Reagan commissioned William Nierenberg to serve on the National Science Board. Nierenberg selected scientists including Gene Likens to serve on a panel to draft a report on acid rain. In 1983, the panel of scientists came up with a draft report, which concluded that acid rain is a real problem and solutions should be sought. White House Office of Science and Technology Policy reviewed the draft report and sent Fred Singer's suggestions of the report, which cast doubt on the cause of acid rain. The panelists revealed rejections against Singer's positions and submitted the report to Nierenberg in April. In May 1983, the House of Representatives voted against legislation that aimed to control sulfur emissions. There was a debate about whether Nierenberg delayed to release the report. Nierenberg himself denied the saying about his suppression of the report and stated that the report was withheld after the House's vote because it was not ready to be published.

In 1991, the US National Acid Precipitation Assessment Program (NAPAP) provided its first assessment of acid rain in the United States. It reported that 5% of New England Lakes were acidic, with sulfates being the most common problem. They noted that 2% of the lakes could no longer support Brook Trout, and 6% of the lakes were unsuitable for the survival of many species of minnow. Subsequent Reports to Congress have documented chemical changes in soil and freshwater ecosystems, nitrogen saturation, decreases in amounts of nutrients in soil, episodic acidification, regional haze, and damage to historical monuments.

Meanwhile, in 1990, the US Congress passed a series of amendments to the Clean Air Act. Title IV of these amendments established a cap and trade system designed to control emissions of sulfur dioxide and nitrogen oxides. Both these emissions proved to cause a significant problem on U.S. citizens and their access to healthy clean air. Title IV called for a total reduction of about 10 million tons of SO2 emissions from power plants, close to a 50% reduction. It was implemented in two phases. Phase I began in 1995, and limited sulfur dioxide emissions from 110 of the largest power plants to a combined total of 8.7 million tons of sulfur dioxide. One power plant in New England (Merrimack) was in Phase I. Four other plants (Newington, Mount Tom, Brayton Point, and Salem Harbor) were added under other provisions of the program. Phase II began in 2000, and affects most of the power plants in the country.

During the 1990s, research continued. On March 10, 2005, the EPA issued the Clean Air Interstate Rule (CAIR). This rule provides states with a solution to the problem of power plant pollution that drifts from one state to another. CAIR will permanently cap emissions of SO2 and NOx in the eastern United States. When fully implemented, CAIR will reduce SO2 emissions in 28 eastern states and the District of Columbia by over 70% and NOx emissions by over 60% from 2003 levels.

Overall, the program's cap and trade program has been successful in achieving its goals. Since the 1990s, SO2 emissions have dropped 40%, and according to the Pacific Research Institute, acid rain levels have dropped 65% since 1976. Conventional regulation was used in the European Union, which saw a decrease of over 70% in SO2 emissions during the same time period.

In 2007, total SO2 emissions were 8.9 million tons, achieving the program's long-term goal ahead of the 2010 statutory deadline.

In 2007 the EPA estimated that by 2010, the overall costs of complying with the program for businesses and consumers would be $1 billion to $2 billion a year, only one fourth of what was originally predicted. Forbes says: "In 2010, by which time the cap and trade system had been augmented by the George W. Bush administration's Clean Air Interstate Rule, SO2 emissions had fallen to 5.1 million tons."

The term citizen science can be traced back as far as January 1989 to a campaign by the Audubon Society to measure acid rain. Scientist Muki Haklay cites in a policy report for the Wilson Center entitled 'Citizen Science and Policy: A European Perspective' a first use of the term 'citizen science' by R. Kerson in the magazine MIT Technology Review from January 1989. Quoting from the Wilson Center report: "The new form of engagement in science received the name "citizen science". The first recorded example of the use of the term is from 1989, describing how 225 volunteers across the US collected rain samples to assist the Audubon Society in an acid-rain awareness raising campaign. The volunteers collected samples, checked for acidity, and reported back to the organization. The information was then used to demonstrate the full extent of the phenomenon."

In Canada
Canadian Harold Harvey was among the first to research a "dead" lake. In 1971, he and R. J. Beamish published a report, "Acidification of the La Cloche Mountain Lakes", documenting the gradual deterioration of fish stocks in 60 lakes in Killarney Park in Ontario, which they had been studying systematically since 1966.

In the 1970s and 80s, acid rain was a major topic of research at the Experimental Lakes Area (ELA) in Northwestern Ontario, Canada. Researchers added sulfuric acid to whole lakes in controlled ecosystem experiments to simulate the effects of acid rain. Because its remote conditions allowed for whole-ecosystem experiments, research at the ELA showed that the effect of acid rain on fish populations started at concentrations much lower than those observed in laboratory experiments. In the context of a food web, fish populations crashed earlier than when acid rain had direct toxic effects to the fish because the acidity led to crashes in prey populations (e.g. mysids). As experimental acid inputs were reduced, fish populations and lake ecosystems recovered at least partially, although invertebrate populations have still not completely returned to the baseline conditions. This research showed both that acidification was linked to declining fish populations and that the effects could be reversed if sulfuric acid emissions decreased, and influenced policy in Canada and the United States.

In 1985, seven Canadian provinces (all except British Columbia, Alberta, and Saskatchewan) and the federal government signed the Eastern Canada Acid Rain Program. The provinces agreed to limit their combined sulfur dioxide emissions to 2.3 million tonnes by 1994. The Canada-US Air Quality Agreement was signed in 1991. In 1998, all federal, provincial, and territorial Ministers of Energy and Environment signed The Canada-Wide Acid Rain Strategy for Post-2000, which was designed to protect lakes that are more sensitive than those protected by earlier policies.

In India
Increased risk might be posed by the expected rise in total sulphur emissions from 4,400 kilotonnes (kt) in 1990 to 6,500 kt in 2000, 10,900 kt in 2010 and 18,500 in 2020.

Emissions of chemicals leading to acidification
The most important gas which leads to acidification is sulfur dioxide. Emissions of nitrogen oxides which are oxidized to form nitric acid are of increasing importance due to stricter controls on emissions of sulfur compounds. 70 Tg(S) per year in the form of SO2 comes from fossil fuel combustion and industry, 2.8 Tg(S) from wildfires, and 7–8 Tg(S) per year from volcanoes.

Natural phenomena
The principal natural phenomena that contribute acid-producing gases to the atmosphere are emissions from volcanoes. Thus, for example, fumaroles from the Laguna Caliente crater of Poás Volcano create extremely high amounts of acid rain and fog, with acidity as high as a pH of 2, clearing an area of any vegetation and frequently causing irritation to the eyes and lungs of inhabitants in nearby settlements. Acid-producing gasses are also created by biological processes that occur on the land, in wetlands, and in the oceans. The major biological source of sulfur compounds is dimethyl sulfide.

Nitric acid in rainwater is an important source of fixed nitrogen for plant life, and is also produced by electrical activity in the atmosphere such as lightning.

Acidic deposits have been detected in glacial ice thousands of years old in remote parts of the globe.

Human activity
The principal cause of acid rain is sulfur and nitrogen compounds from human sources, such as electricity generation, animal agriculture, factories, and motor vehicles. These also include power plants, which use electric power generators that account for a quarter of nitrogen oxides and two-thirds of sulfur dioxide within the atmosphere. Industrial acid rain is a substantial problem in China and Russia and areas downwind from them. These areas all burn sulfur-containing coal to generate heat and electricity.

The problem of acid rain has not only increased with population and industrial growth, but has become more widespread. The use of tall smokestacks to reduce local pollution has contributed to the spread of acid rain by releasing gases into regional atmospheric circulation; dispersal from these taller stacks causes pollutants to be carried farther, causing widespread ecological damage. Often deposition occurs a considerable distance downwind of the emissions, with mountainous regions tending to receive the greatest deposition (because of their higher rainfall). An example of this effect is the low pH of rain which falls in Scandinavia. Regarding low pH and pH imbalances in correlation to acid rain, low levels, or those under the pH value of 7, are considered acidic. Acid rain falls at a pH value of roughly 4, making it harmful to consume for humans. When these low pH levels fall in specific regions, they not only affect the environment but also human health. With acidic pH levels in humans comes hair loss, low urinary pH, severe mineral imbalances, constipation, and many cases of chronic disorders like Fibromyalgia and Basal Carcinoma.

Chemical process
Combustion of fuels produces sulfur dioxide and nitric oxides. They are converted into sulfuric acid and nitric acid.

Gas phase chemistry
In the gas phase sulfur dioxide is oxidized by reaction with the hydroxyl radical via an intermolecular reaction:
 * SO2 + OH· → HOSO2·

which is followed by:
 * HOSO2· + O2 → HO2· + SO3

In the presence of water, sulfur trioxide (SO3) is converted rapidly to sulfuric acid:
 * SO3 (g) + H2O (l) → H2SO4 (aq)

Nitrogen dioxide reacts with OH to form nitric acid:
 * NO2 + OH· → HNO3

Chemistry in cloud droplets
When clouds are present, the loss rate of SO2 is faster than can be explained by gas phase chemistry alone. This is due to reactions in the liquid water droplets.

 * Hydrolysis

Sulfur dioxide dissolves in water and then, like carbon dioxide, hydrolyses in a series of equilibrium reactions:

 * SO2 (g) + H2O SO2·H2O
 * SO2·H2O H+ + HSO3−
 * HSO3− H+ + SO32−

 * Oxidation

There are a large number of aqueous reactions that oxidize sulfur from S(IV) to S(VI), leading to the formation of sulfuric acid. The most important oxidation reactions are with ozone, hydrogen peroxide and oxygen (reactions with oxygen are catalyzed by iron and manganese in the cloud droplets).

Wet deposition
Wet deposition of acids occurs when any form of precipitation (rain, snow, and so on) removes acids from the atmosphere and delivers it to the Earth's surface. This can result from the deposition of acids produced in the raindrops (see aqueous phase chemistry above) or by the precipitation removing the acids either in clouds or below clouds. Wet removal of both gases and aerosols are both of importance for wet deposition.

CAM plants are predominantly found in arid environments, where water availability is limited.

Dry deposition
Acid deposition also occurs via dry deposition in the absence of precipitation. This can be responsible for as much as 20 to 60% of total acid deposition. This occurs when particles and gases stick to the ground, plants or other surfaces.

Adverse effects
Acid rain has been shown to have adverse impacts on forests, freshwaters and soils, killing insect and aquatic life-forms as well as causing damage to buildings and having impacts on human health.

Surface waters and aquatic animals
Both the lower pH and higher aluminium concentrations in surface water that occur as a result of acid rain can cause damage to fish and other aquatic animals. At pH lower than 5 most fish eggs will not hatch and lower pH can kill adult fish. As lakes and rivers become more acidic biodiversity is reduced. Acid rain has eliminated insect life and some fish species, including the brook trout in some lakes, streams, and creeks in geographically sensitive areas, such as the Adirondack Mountains of the United States.

However, the extent to which acid rain contributes directly or indirectly via runoff from the catchment to lake and river acidity (i.e., depending on characteristics of the surrounding watershed) is variable. The United States Environmental Protection Agency's (EPA) website states: "Of the lakes and streams surveyed, acid rain caused acidity in 75% of the acidic lakes and about 50% of the acidic streams". Lakes hosted by silicate basement rocks are more acidic than lakes within limestone or other basement rocks with a carbonate composition (i.e. marble) due to buffering effects by carbonate minerals, even with the same amount of acid rain.

Sulfur dioxide and nitrous oxide concentration has many implication on aquatic ecosystems, including acidity change, increased nitrogen and aluminum content, and altering biogeochemical processes. Typically, sulfur dioxide and nitrous oxide do not have direct physiological effects upon exposure; most effects are developed by accumulation and prolonged exposure of these gases in the environment, modifying soil and water chemistry.

Soils
Soil biology and chemistry can be seriously damaged by acid rain. Some microbes are unable to tolerate changes to low pH and are killed. The enzymes of these microbes are denatured (changed in shape so they no longer function) by the acid. The hydronium ions of acid rain also mobilize toxins, such as aluminium, and leach away essential nutrients and minerals such as magnesium.

 * 2 H+ (aq) + Mg2+ (clay) 2 H+ (clay) + Mg2+ (aq)

Soil chemistry can be dramatically changed when base cations, such as calcium and magnesium, are leached by acid rain, thereby affecting sensitive species, such as sugar maple (Acer saccharum).

 Soil acidification  Impacts of acidic water and soil acidification on plants could be minor or in most cases major. Most minor cases which do not result in fatality of plant life can be attributed to the plants being less susceptible to acidic conditions and/or the acid rain being less potent. However, even in minor cases, the plant will eventually die due to the acidic water lowering the plant's natural pH. Acidic water enters the plant and causes important plant minerals to dissolve and get carried away; which ultimately causes the plant to die of lack of minerals for nutrition. In major cases, which are more extreme, the same process of damage occurs as in minor cases, which is removal of essential minerals, but at a much quicker rate. Likewise, acid rain that falls on soil and on plant leaves causes drying of the waxy leaf cuticle, which ultimately causes rapid water loss from the plant to the outside atmosphere and eventually results in death of the plant. Soil acidification can lead to a decline in soil microbes as a result of a change in pH, which would have an adverse effect on plants due to their dependence on soil microbes to access nutrients. To see if a plant is being affected by soil acidification, one can closely observe the plant leaves. If the leaves are green and look healthy, the soil pH is normal and acceptable for plant life. But if the plant leaves have yellowing between the veins on their leaves, that means the plant is suffering from acidification and is unhealthy. Moreover, a plant suffering from soil acidification cannot photosynthesize; the acid-water-induced process of drying out of the plant can destroy chloroplast organelles. Without being able to photosynthesize, a plant cannot create nutrients for its own survival or oxygen for the survival of aerobic organisms, which affects most species on Earth and ultimately ends the purpose of the plant's existence.

Forests and other vegetation
Adverse effects may be indirectly related to acid rain, like the acid's effects on soil (see above) or high concentration of gaseous precursors to acid rain. High altitude forests are especially vulnerable as they are often surrounded by clouds and fog which are more acidic than rain.

Plants are capable of adapting to acid rain. On Jinyun Mountain, Chongqing, plant species were seen adapting to new environmental conditions. The affects on the species ranged from being beneficial to detrimental. With natural rainfall or mild acid rainfall, the biochemical and physiological characteristics of plant seedlings were enhanced. Once the pH increases reaches the threshold of 3.5, the acid rain can no longer be beneficial and begins to have negative affects.

Acid rain can negatively impact photosynthesis in plant leaves, when leaves are exposed to a lower pH, photosynthesis is impacted due to the decline in chlorophyll. Acid rain also has the ability to cause deformation to leaves at a cellular level, examples include; tissue scaring and changes to the stomatal, epidermis and mesophyll cells. Additional impacts of acid rain includes a decline in cuticle thickness present on the leaf surface. Because acid rain damages leaves, this directly impacts a plants ability to have a strong canopy cover, a decline in canopy cover can lead plants to be more vulnerable to diseases.

Dead or dying trees often appear in areas impacted by acid rain. Acid rain causes aluminum to leach from the soil, posing risks to both plant and animal life. Furthermore, it strips the soil of critical minerals and nutrients necessary for tree growth.

At higher altitudes, acidic fog and clouds can deplete nutrients from tree foliage, leading to discolored or dead leaves and needles. This depletion compromises the trees' ability to absorb sunlight, weakening them and diminishing their capacity to endure cold conditions.

Other plants can also be damaged by acid rain, but the effect on food crops is minimized by the application of lime and fertilizers to replace lost nutrients. In cultivated areas, limestone may also be added to increase the ability of the soil to keep the pH stable, but this tactic is largely unusable in the case of wilderness lands. When calcium is leached from the needles of red spruce, these trees become less cold tolerant and exhibit winter injury and even death. Acid rain may also affect crop productivity by necrosis or changes to soil nutrients, which ultimately prevent plants from reaching maturity.

Ocean acidification
Acid rain has a much less harmful effect on oceans on a global scale, but it creates an amplified impact in the shallower waters of coastal waters. Acid rain can cause the ocean's pH to fall, known as ocean acidification, making it more difficult for different coastal species to create their exoskeletons that they need to survive. These coastal species link together as part of the ocean's food chain, and without them being a source for other marine life to feed off of, more marine life will die. Coral's limestone skeleton is particularly sensitive to pH decreases, because the calcium carbonate, a core component of the limestone skeleton, dissolves in acidic (low pH) solutions.

In addition to acidification, excess nitrogen inputs from the atmosphere promote increased growth of phytoplankton and other marine plants, which, in turn, may cause more frequent harmful algal blooms and eutrophication (the creation of oxygen-depleted "dead zones") in some parts of the ocean.

Human health effects
Acid rain can negatively impact human health, especially when people breathe in particles released from acid rain. The effects of acid rain on human health are complex and may be seen in several ways, such as respiratory issues for long-term exposure and indirect exposure through contaminated food and water sources.

Nitrogen Dioxide Effects
Exposure to air pollutants associated with acid rain, such as nitrogen dioxide (NO2), may have a negative impact on respiratory health. Water-soluble nitrogen dioxide accumulates in the tiny airways, where it is transformed into nitric and nitrous acids. Pneumonia caused by nitric acids directly damages the epithelial cells lining the airways, resulting in pulmonary edema. Exposure to nitrogen dioxide also reduces the immune response by inhibiting the generation of inflammatory cytokines by alveolar macrophages in response to bacterial infection. In animal studies, the pollutant further reduces respiratory immunity by decreasing mucociliary clearance in the lower respiratory tract, which results in a reduced ability to remove respiratory infections.

Sulfur Trioxide Effects
The effects of sulfur trioxide and sulfuric acid are similar because they both produce sulfuric acid when they come into touch with the wet surfaces of your skin or respiratory system. The amount of SO3 breath through the mouth is larger than the amount of SO3 breath through the nose. When humans breathe in sulfur trioxide, small droplets of sulfuric acid will form inside the body and enter the respiratory tract to the lungs depending on the particle size. The effects of SO3 on the respiratory system lead to breathing difficulty in people who have asthma symptoms. Sulfur trioxide also causes very corrosive and irritation on the skin, eye, and gastrointestinal tracts when there is direct exposure to a specific concentration or long-term exposure. Consuming concentrated sulfuric acid has been known to cause mortality, burn the mouth and throat, erode a hole in the stomach, burns skin when it comes into contact with skin, and make your eyes weep if it gets into them.

Nitrogen Dioxides
A 25 parts per million (ppm) maximum for nitric oxide in working air has been set by the Occupational Safety and Health Administration (OSHA) for an 8-hour workday and a 40-hour workweek. Additionally, OSHA has established a 5-ppm nitrogen dioxide exposure limit for 15 minutes in the workplace.

Sulfur Trioxide
The not-to-exceed limits in the air, water, soil, or food that are recommended by regulations are often based on levels that affect animals before being modified to assist in safeguarding people. Depending on whether they employ different animal studies, have different exposure lengths (e.g., an 8-hour workday versus a 24-hour day), or for other reasons, these not-to-exceed values can vary between federal bodies.

The amount of sulfur dioxide that can be emitted into the atmosphere is capped by the EPA. This reduces the quantity of sulfur dioxide in the air that turns into sulfur trioxide and sulfuric acid. Sulfuric acid concentrations in workroom air are restricted by OSHA to 1 mg/m³. Moreover, NIOSH advises a time-weighted average limit of 1 mg/m³.

When you are aware of NO2 and SO3 exposure, you should talk to your doctor and ask people who are around you, especially children.

Other adverse effects
Acid rain can damage buildings, historic monuments, and statues, especially those made of rocks, such as limestone and marble, that contain large amounts of calcium carbonate. Acids in the rain react with the calcium compounds in the stones to create gypsum, which then flakes off.

 * CaCO3 (s) + H2SO4 (aq) CaSO4 (s) + CO2 (g) + H2O (l)

The effects of this are commonly seen on old gravestones, where acid rain can cause the inscriptions to become completely illegible. Acid rain also increases the corrosion rate of metals, in particular iron, steel, copper and bronze.

Affected areas
Places significantly impacted by acid rain around the globe include most of eastern Europe from Poland northward into Scandinavia, the eastern third of the United States, and southeastern Canada. Other affected areas include the southeastern coast of China and Taiwan.

Technical solutions
Many coal-firing power stations use flue-gas desulfurization (FGD) to remove sulfur-containing gases from their stack gases. For a typical coal-fired power station, FGD will remove 95% or more of the SO2 in the flue gases. An example of FGD is the wet scrubber which is commonly used. A wet scrubber is basically a reaction tower equipped with a fan that extracts hot smoke stack gases from a power plant into the tower. Lime or limestone in slurry form is also injected into the tower to mix with the stack gases and combine with the sulfur dioxide present. The calcium carbonate of the limestone produces pH-neutral calcium sulfate that is physically removed from the scrubber. That is, the scrubber turns sulfur pollution into industrial sulfates.

In some areas the sulfates are sold to chemical companies as gypsum when the purity of calcium sulfate is high. In others, they are placed in landfill. The effects of acid rain can last for generations, as the effects of pH level change can stimulate the continued leaching of undesirable chemicals into otherwise pristine water sources, killing off vulnerable insect and fish species and blocking efforts to restore native life.

Fluidized bed combustion also reduces the amount of sulfur emitted by power production.

Vehicle emissions control reduces emissions of nitrogen oxides from motor vehicles.

International treaties
International treaties on the long-range transport of atmospheric pollutants have been agreed upon by western countries for some time now. Beginning in 1979, European countries convened in order to ratify general principles discussed during the UNECE Convention. The purpose was to combat Long-Range Transboundary Air Pollution. The 1985 Helsinki Protocol on the Reduction of Sulfur Emissions under the Convention on Long-Range Transboundary Air Pollution furthered the results of the convention. Results of the treaty have already come to fruition, as evidenced by an approximate 40 percent drop in particulate matter in North America. The effectiveness of the Convention in combatting acid rain has inspired further acts of international commitment to prevent the proliferation of particulate matter. Canada and the US signed the Air Quality Agreement in 1991. Most European countries and Canada signed the treaties. Activity of the Long-Range Transboundary Air Pollution Convention remained dormant after 1999, when 27 countries convened to further reduce the effects of acid rain. In 2000, foreign cooperation to prevent acid rain was sparked in Asia for the first time. Ten diplomats from countries ranging throughout the continent convened to discuss ways to prevent acid rain. Following these discussions, the Acid Deposition Monitoring Network in East Asia (EANET) was established in 2001 as an intergovernmental initiative to provide science-based inputs for decision makers and promote international cooperation on acid deposition in East Asia. In 2023, the EANET member countries include Cambodia, China, Indonesia, Japan, Lao PDR, Malaysia, Mongolia, Myanmar, the Philippines, Republic of Korea, Russia, Thailand and Vietnam.

Emissions trading
In this regulatory scheme, every current polluting facility is given or may purchase on an open market an emissions allowance for each unit of a designated pollutant it emits. Operators can then install pollution control equipment, and sell portions of their emissions allowances they no longer need for their own operations, thereby recovering some of the capital cost of their investment in such equipment. The intention is to give operators economic incentives to install pollution controls.

The first emissions trading market was established in the United States by enactment of the Clean Air Act Amendments of 1990. The overall goal of the Acid Rain Program established by the Act is to achieve significant environmental and public health benefits through reductions in emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx), the primary causes of acid rain. To achieve this goal at the lowest cost to society, the program employs both regulatory and market based approaches for controlling air pollution.

title: Acid rain


text:
Acephali

In church history, the term acephali (from Ancient Greek: ἀκέφαλοι akephaloi, "headless", singular ἀκέφαλος akephalos from ἀ- a-, "without", and κεφαλή kephalé, "head") has been applied to several sects that supposedly had no leader. E. Cobham Brewer wrote, in Dictionary of Phrase and Fable, that acephalites, "properly means men without a head." Jean Cooper wrote, in Dictionary of Christianity, that it characterizes "various schismatical Christian bodies". Among them were Nestorians who rejected the Council of Ephesus’ condemnation of Patriarch Nestorius of Constantinople, which deposed Nestorius and declared him a heretic.

Fifth-century acephali
Those who refused to acknowledge the authority of the Council of Chalcedon were originally called Haesitantes; the Acephali developed from among them, and, according to Blunt, the earlier name – Haesitantes – seems to have been used for only a short time.

With the apparent purpose of bringing the Orthodox and heretics into unity, Patriarch Peter III of Alexandria and Patriarch Acacius of Constantinople had elaborated a new creed in which they expressly condemned both Nestorius and Eutyches, a presbyter and archimandrite, but at the same time rejected the decisions of the Council of Chalcedon. This ambiguous formula, though approved by Byzantine Emperor Zeno and imposed in his Henoticon, could only satisfy the indifferent.

The term applied to a 5th-century faction among the Eutychians, who seceded from Peter, a Miaphysite, in 482, after Peter signed the Henoticon and was recognised by Zeno as the legitimate patriarch of Alexandria, by which they were "deprived of their head". They remained "without king or bishop" until they were reconciled with Coptic Orthodox Pope Mark II of Alexandria (799–819). The condemnation of Eutyches irritated the rigid Monophysites; the equivocal attitude taken towards the Council of Chalcedon appeared to them insufficient, and many of them, especially the monks, deserted Peter, preferring to be without a head, rather than remain in communion with him. Later, they joined the adherents of the non-Chalcedonian Patriarch Severus of Antioch. They were, according to Oxford English Dictionary Online, a "group of extreme Monophysites" and "were absorbed by the Jacobites".

Liberatus of Carthage wrote, in Breviarium causae Nestorianorum et Eutychianorum, that those at the Council of Ephesus who followed neither Patriarch Cyril I of Alexandria nor Patriarch John I of Antioch were called Acephali.

Esaianites were one of the sects into which the Alexandrian Acephali separated at the end of the 5th century. They were the followers of Esaias, a deacon of Palestine, who claimed to have been consecrated to the episcopal office by the Bishop Eusebius. His opponents averred that after the bishop's death, his hands had been laid upon the head of Esaias by some of his friends.

Paulitae were a sect of Acephali who followed Chalcedonian Patriarch Paul of Alexandria, who was deposed by a synod at Gaza, in 541, for his uncanonical consecration by the Patriarch of Constantinople, and who, after his deposition, sided with the Miaphysites.

Barsanians, later called Semidalites, were a sect of Acephali at the end of the 5th century. They had no succession of priests, and professed to keep up the celebration of a valid Eucharist by placing a few crumbs of some of the bread which had been consecrated by Dioscorus into a vessel of meal, and then using as fully consecrated the bread baked from it.

The Barsanuphians separated from the Acephali in the late 6th century and developed their own episcopal hierarchy.

Other acephali
According to Brewer, acephalites were also certain bishops exempt from the jurisdiction and discipline of their patriarch. Cooper explains that they are "priests rejecting episcopal authority or bishops that of their metropolitans." Blunt described clerici acephali as those clergy who were ordained with a sinecure benefice and who generally obtained their orders by paying for them, that is, by simony. The Council of Pavia, in 853, legislated its canons 18 and 23 against them, from which it appears, according to Blunt, that they were mostly chaplains to noblemen, that they produced much scandal in the Church, and that they disseminated many errors.

clergy without title or benefice.

According to Brewer, acephalites were also a sect of Levellers during the reign of Henry I of England who acknowledged no leader. They were, according to Oxford English Dictionary Online, "a group of free socagers having no feudal superior except the king." This usage is now considered obsolete.

title: Acephali


text:
Talk:Aborigines

From the original encyclopedia article:

 * The Aborigines' Protection Society was founded in 1838 in England as the result of a royal commission appointed at the instance of Sir T. Fowell Buxton to inquire into the treatment of the indigenous populations of the various British colonies. The inquiry revealed the gross cruelty and injustice with which the natives had been often treated.  Since its foundation the society has done much to make English colonization a synonym for humane and generous treatment of savage races.

Hmmm. It seems like back in the 1830's at least some people who mattered realised that "the colonies" were treating their native populations unjustly and cruelly. Wonder how long it's going to take certain Australian politicians to admit it :/

title: Talk:Aborigines