A Venn diagram is a diagram that shows the logical relation between sets. They were popularised by John Venn in the 1880s, and are now widely used. They are used to teach elementary set theory, and to illustrate simple set relationships in probability, logic, statistics, linguistics and computer science. A Venn diagram uses closed curves drawn on a plane to represent sets. Very often, these curves are circles or ellipses.

Similar ideas had been proposed before Venn. Christian Weise in 1712 (Nucleus Logicoe Wiesianoe) and Leonhard Euler (Letters to a German Princess) in 1768, for instance, came up with similar ideas. The idea was popularised by Venn in Symbolic Logic, Chapter V "Diagrammatic Representation", 1881.

Example

The following example uses two sets, A and B, represented here as coloured circles. The orange circle, set A, represents all living creatures that are two-legged. The blue circle, set B, represents the living creatures that can fly. Each separate type of creature can be imagined as a point somewhere in the diagram. Living creatures that can both fly and have two legs—for example, parrots—are then in both sets, and hence correspond to points in the area where the blue and orange circles overlap. That area contains all such (and only) such living creatures.

Humans and penguins are bipedal, and hence are in the orange circle, but since they cannot fly, they appear in the left part of the orange circle, where it does not overlap with the blue circle. Mosquitoes have six legs, and fly, so the point for mosquitoes is in the part of the blue circle that does not overlap with the orange one. Creatures that are not two-legged and cannot fly (for example, whales and spiders) would all be represented by points outside both circles.

The combined area of sets A and B is called the union of A and B, denoted by . The union in this case contains all living creatures that are either two-legged, or that can fly (or both).
The area in both A and B, where the two sets overlap, is called the intersection of A and B, denoted by . For example, the intersection of the two sets is not empty, because there are points that represent creatures that are in both the orange and blue circles.

Venn diagrams of common operations on sets

In the illustrations below the left circle shows set  and the right circle shows set . Results of operations are shown as colored areas.

Related pages

 Exclusive disjunction
 Inclusive disjunction

References

Set theory

Venn diagram


A caravan (from ) is a group of people traveling together. Often they are on a trade expedition. Caravans were used mainly in desert areas and throughout the Silk Road. Traveling in groups aided in defense against bandits, in the same way that convoys at sea helped protect against piracy. It also helped improve economies of scale in trade. In the 14th century there were reports of caravans of up to 12,000 camels.

In historical times, caravans traveled across East Asia and Europe. They often carried luxurious and lucrative goods, such as silks or jewelry. They would trade these for salt, gold, copper or slaves. At first donkey carts were used. They were replaced with the single hump camel. The camel could go great distances on very little water.

Caravans could require a large investment in goods and camels. They were a rich target for bandits. The profits from a successful trade journey could be great. Many rulers along important trade routes created caravanserai (way stations). These were places where caravans could refresh their animals and supplies can be replenished. However, the volume a caravan could transport was limited. For example, a caravan of 500 camels could only transport as much as a third or half of the goods carried by a regular Byzantine merchant sailing ship.

Present-day caravans still transport important goods in less-developed areas of the world. Examples are the camel trains traversing the southern edges of the Sahara Desert. Also, modern caravans are often made up of cars, trucks and busses.

References

Transport

Caravan (travellers)


Pollyanna is a book for children written by Eleanor Hodgman Porter. It was published in 1913.

Pollyanna-The game Story
A girl called Pollyanna is an orphan (her parents are dead). She goes to live with her Aunt Polly (who did not marry) in Beldingsville, Vermont. Pollyanna is happy all the time, and makes other people happy. She plays a game called the "glad game", where you find something to be happy about even when you are sad. Soon, everyone in the town is happy. An accident occurs and Pollyanna is left unable to move her legs.  She has to learn to be happy again, and then she gets better because a doctor makes her well again. Aunt Polly and the doctor marry.

Summary of the story

Miss Polly Harrington is known around town for being a stern, hard woman who is set in her ways. So it is only a sense of duty that causes her to open her home to Pollyanna, her newly orphaned niece. But Pollyanna is a very special little girl, with a very special game that she teaches to the townspeople. Soon, everyone in town is happier, and glad that Pollyanna came into their lives - everyone, that is, but Aunt Polly. But then a terrible accident threatens to ruin Pollyanna's game forever, and everyone wonders who can teach this little girl to be happy again.

Notes
If someone is called "Pollyanna", it means they are always happy like Pollyanna is. The "Pollyanna principle" means people say yes to positive statements (For example, instead of "What do you think of green?", you can say "Don't you agree that green is a nice colour?").

Pollyanna was an irrepressibly, cheerful child. So cheerful that her name survives in any standard American Dictionary. - 'an excessively or blindly optimistic person.'

Other websites
Text of the book

1910s books
20th-century American novels
American children's books

Pollyanna


The Allied Powers of World War I were the countries who fought against the Central Powers in World War I. Major countries included the British Empire, France, the Russian Empire, the United States, Italy, and Japan. Most of these countries would fight alongside each other again in World War II, except that Italy and Japan would fight alongside Germany instead.

The Allied Powers in Europe were already allies before the war began. Serbia was an ally of Russia, and Russia was an ally of Britain and France. The war started because the Austro-Hungarian Empire declared war on Serbia in 1914, which led to a chain reaction of countries declaring war on each other.

At first, the United States was neutral, it was not part of either side. However, after several acts made by Germany against the US, the US declared war on Germany in 1917 and would fight for the Allied Powers.

Russia's campaign against the Central Powers went very poorly. Many Russian soldiers were poorly equipped and trained, many Russians were killed, and poverty and starvation became worse problems than before. Many Russians blamed Czar Nicholas II's poor leadership for Russia's problems, so he was overthrown and sent to exile. The Russian Provisional Government who replaced him also made many Russians upset because they promised that Russia would continue fighting the war. After the March Revolution that overthrew the Czar, communist revolutionary Vladimir Lenin made a deal with Germany. The deal was that he would stop the fighting between Russia and Germany if they sent him to Russia to overthrow the government. Lenin's slogan for his communist government was "peace, land, and bread". This meant that the communist government promised no more fighting in the war, land redistribution so that everyone in Russia could have an equal amount of property, and that food would be plentiful. After the Communist Party took over Russia in the October Revolution, they fulfilled their promise to Germany and ended Russia's fighting in the war.

In World War II, Italy would join Germany in the Axis Powers because its leader, Benito Mussolini, had a similar ideology to Nazism. Japan was disappointed with the end of World War I because it did not gain as much as it wanted. Japan would also join the Axis Powers because it thought it would help the Japanese Empire grow faster than if it did with the Allies.

World War I

Allied Powers of World War I


Oak–hickory forest is a type of North American forest ecosystem, and an ecoregion of the Temperate broadleaf and mixed forests Biome.

Geography
It has a range extending from Rhode Island and southern New York, west to Iowa, and south to Northern Georgia. Smaller, isolated oak–hickory communities can also be found as far west as North Dakota, south in Florida and in northeast Texas, and north to southern Maine and Ontario. They can also be found in Pennsylvania west to Illinois.

Dominated by nut-bearing oak and hickory species of trees, the oak–hickory forest has the largest range of any deciduous forest ecosystem in eastern and central North America.

Natural history
The current oak–hickory forest includes the former range of the oak–chestnut forest region, which encompassed the northeast portion of the current oak–hickory range. When the American chestnut population succumbed to invasive fungal blight in the early 20th century, those forests shifted to an oak and hickory dominated ecosystem.

Biota
Key indicator tree and shrub species of the oak–hickory forest include red oak, black oak, scarlet oak, white oak, Chestnut oak (Quercus prinus), Pignut hickory (Carya glabra), Bitternut hickory (Carya cordiformis), Shagbark hickory (Carya ovata), flowering dogwood (Cornus florida), blueberry, Mountain laurel (Kalmia latifolia), and hawthorn.

Bird and animal species include the gray squirrel, flying squirrel, chipmunk, blue jay, and wild turkey.

References

 Cronin, William. Changes in the Land: Indians, Colonists, and the Ecology of New England. Hill and Wang, New York, 2003.
 Kricher, John. A Field Guide to Eastern Forests. Houghton-Mifflin, Boston, 1998.
 "Percent of Forests in Oak-Hickory Groups, 1992." Map, United States Department of Agriculture, 1992.

Temperate broadleaf and mixed forests in the United States
Ecoregions of the United States
Plant communities of the Eastern United States
Flora of the Eastern United States
Plant communities of Kentucky
Plant communities of North Carolina
Plant communities of Ohio
Plant communities of Pennsylvania
Plant communities of South Carolina
Plant communities of Tennessee
Plant communities of Virginia
Plant communities of West Virginia
Ecology of the Appalachian Mountains
Flora of the Northeastern United States
Flora of the Southeastern United States
Flora of Eastern Canada
Flora of the Appalachian Mountains
Flora of Ontario
Forest ecology

Oak–hickory forest


Lake Doxa () is an artificial lake in western Corinthia, Greece. It is situated at an elevation of 900 m, in the municipal unit Feneos, near the village Archaia Feneos. Construction was completed in the late 1990s. It is fed and drained by the small river Doxa (Δόξα), which empties into the plain of Feneos. In the heart of the lake on a small peninsula features a small church of Agios Fanourios. The Saint George Monastery in Feneos was relocated to higher ground, north of the lake. The lake is surrounded by pine forests.

Gallery

External links

Photos of Lake Doxa at TrekEarth
Photos of Lake Doxa on webshots

Landforms of Corinthia
Doxa
Landforms of Peloponnese (region)

Lake Doxa


Bon-Bon Blanco (sometimes B3 or B3) is a Japanese rock group during 2002–2009. The group used to belong to Columbia Music Entertainment, but has moved to Bouncy Records in 2006.

Members
Its members are:
 Anna Santos (サントス・アンナ Santosu Anna, born July 9, 1987) – Main Vocals
 Izumi (中台泉美 Nakadai Izumi, born January 2, 1988) – Conga
 Mako (桜井真子 Sakurai Mako, born October 7, 1986) – Maracas, ex-leader
 Ruri (水谷光里 Mizutani Ruri, born January 7, 1990) – Bongo
 Tomoyo (松本知世 Matsumoto Tomoyo, born March 2, 1987) – Timbales, current leader

History

Formation of the group
The group formed in 2002 with 4 members of a group named Nansho Kids: Mako Sakurai, Izumi Nakadai, Tomoyo Matsumoto, and Ruri Mizutani (sister of a famous actress, Yuri Mizutani) and added Santos Anna (who appeared in a Japanese version of Annie) as a vocalist and debuted at Bandai display corner at the Tokyo Toy Show in May of the same year. Their unique style, 4 percussionists and 1 vocalist, attracted a lot of attention from media in Japan even before they debuted. With an average age of 14 at the time of debut, they were also gracing the cover of music magazines. In June of the same year, their official Website "B3 TV" was opened.

First single
On July 17, 2002, they released their first single "Ai want you!!". The song was written by Paninaro 30 (lyric) and ex-Wands Kosuke Oshima (music). During July 24 to August 28, they performed weekly concerts at a live house named Harajuku Ruido. The low cost of the cover (500 yen including drinks, roughly 5 dollars USD), the completeness of the performance, as well as the word of mouth helped to fill the house consistently.

The quality of their music had been assured because one of Japanese major record labels, Being, has been supporting them since their debut. And as the members started to improve in terms of their percussion skills, their popularity also shot up. On December 26, they had a concert at Harajuku Ruido again, and this time the live house was sold out within the same day. The door of the live house wouldn't close due to the amount of audience.

During this period of time, a selection of songs were performed without instruments and was called "Dance Version". This was met with a decent amount of critics approval, labeling them as a dance unit. With the improved abilities of the members, the frequency of the "Dance Versions" of the songs decreased, and there have been fans that wish to bring some of the dancing back.

Smashing Hit
The turning point had come in 2004. Their 6th single, 'Bon Voyage' was used as a theme of a famous animation program, 'One Piece', and  it became No. 8 at hit charts in Japan. And Bon-Bon Blanco's name finally was recognized by a lot of  people. And with 7th single, 'Tenohira wo Taiyo ni', they visited a lot of elementary schools, including the school Anna graduated. This song is the 4th cover song of the group after 'Conga'  from Miami Sound Machine and 'Come to me' from Bobby Caldwell, And 'Ureshii Tanoshii Daisuki' from Dreams Come True,  all of which are included in their 2nd album, 'B3 masterpieces 2002–2004'.

Rise and Fall
However, after the hit of 'Bon Voyage', the gap between the group aiming at and what fans require was widened graduately, and the sales of copies of each single descended along with that. And after they released 'Ai ga ippai' in 2005, although the group was sometimes guested to some concerts including a musical named 'Angel Gate',  they had to take a factual leave continued for  one and half years.

Revival
On July 25, 2006, they had a concert at Shibuya Bpxx, and it was the beginning of their return. On August 30, they released 'Yura Yura Yureru', from a new record label set up by the producer of Bon-Bon Blanco, Bouncy Records. This is the  song they performed in Angel Gate. In this song, and they renewed  the group's image changing their costumes from jeans and T-shirts to sexy bikinis. Anna challenged to rapping first time.

In 2007, the group started its activity from the concert held at Shibuya O-EAST on January 27. On February 21, they released their 11th single, '∞Changing∞. They had several free concerts in Akihabara from March to July. From July, they started monthly concert titled 'Onnna Matsuri'(女祭) at Shibuya O-West. On February 6, 2008, their first live DVD which includes this 'Onna Matsuri' was released.

Present
On May 14, 2008, Izumi left the group, and other members announced that they will continue their activity as a quartet on their official web site.

Discography

Singles
 'Ai Want You!!' (7/17/2002)
 'Datte, Onna no Ko Nandamon!' (9/11/2002)
 'Ai no Nurse Carnival' (2/19/2003)
 'Namida no Hurricane' (2/19/2003) (2nd ED song for the anime series Get Backers).
 'Vacance no Koi' (6/4/2003)
 'Bon Voyage!' (1/14/2004)(4th theme song for the anime series One Piece)
 'Te no Hira wo Taiyou ni' (7/14/2004)
 'La La Kuchibue Fuite Ikou' (9/1/2004)
Note: This song's lyrics is written by Saori Atsumi.
 'Ai ga Ippai' (2/23/2005)
 'Yura Yura Yureru' (8/30/2006)
 '∞Changing∞' (2/21/2007) (2nd ED song for the anime series Yamato Nadeshiko Shichi Henge, also known as the Wallflower)

Albums
 BEAT GOES ON (3/26/2003)
 B3 Master Pieces 2002–2004 (3/24/2004)
 Winter Greetings (12/15/2004)

DVD
 B3 Master Clips 2002–2004 (3/24/2004)
 Onna Matsuri (2/6/2008)

External links

  statistics and tagging at Last.FM

Notes

Japanese rock music groups
Musical groups from Tokyo
All-female bands

Bon-Bon Blanco


Richard Armstrong (April 13, 1805 – September 23, 1860) was a Presbyterian missionary from Pennsylvania who arrived in Hawaii in 1832. Along with his wife Clarissa, he served in mission fields of the Marquesas Islands and in the Kingdom of Hawaii. He established several churches and schools, and was Kahu (shepherd) of Kawaiahaʻo Church after the departure of Hiram Bingham I. Kamehameha III appointed him Minister of Public Instruction, and his accomplishments established an educational system that earned him the nickname "The father of American education in Hawaii".

Background
Richard Armstrong was born in Northumberland County,  Pennsylvania  on April 13, 1805, to James Armstrong and his American-born wife Eleanor Pollock.  The elder Armstrong had been born in Enniskillen,  County Fermanagh,  Northern Ireland, and in 1786 emigrated to the United States, where he married Eleanor.  The family were Presbyterian. Richard was the youngest child of the union. He was educated at Milton Academy in Massachusetts, furthering his education at Dickinson College in Pennsylvania, and graduating from Princeton Theological Seminary in 1831.

Nuku Hiva and Hawaii
Princeton president Archibald Alexander provided a letter of recommendation In 1831, when Armstrong made the decision to join the next contingent of missionaries being sent to Hawaii by the American Board of Commissioners for Foreign Missions.  He received his ordination on October 27, and Armstrong and his new bride Clarissa Chapman departed with the other missionaries aboard the Averick on November 26. The ship docked in Honolulu on May 17, 1832, with Clarissa seven months pregnant. Daughter and first child Caroline Porter was born in Honolulu on July 17.

The board sent the Armstrongs to minister to cannibalistic tribes on Nuku Hiva in the Marquesas Islands  July 2, 1833, through May 12, 1834, serving alongside missionary couples the Rev. William Patterson Alexander and his wife Mary, and the Rev. Benjamin Wyman Parker and his wife Mary Elizabeth. The  first Armstrong son William Nevins was born on Nuku Hiva on January 2, 1834. The Nuku Hiva mission field was abandoned as futile.

The Armstrongs were reassigned to the Island of Maui, where the infant William Nevins died March 17, 1835, in Lahaina. Their second son had been born two days before on March 15, and he was given the name of his brother William Nevins. In July of that year, the Armstrongs were assigned to Wailuku. Three more children were born during this assignment. Mary Jane was born June 2, 1836, in Honolulu. Two sons were born in Wailuku, Richard Baxter on August 15, 1837, and Samuel Chapman on January 30, 1839. During his assignment on Maui, Armstrong established churches at Waihee, Wailuku, Ulupalakua, and at Haiku, where he also became an 1858 founder of Haiku Sugar Company on land he owned.

In 1840, Armstrong was appointed Kahu (shepherd) of Kawaiahaʻo Church to replace Hiram Bingham I. On August 26, 1854, he was licensed to perform marriages in Hawaii. Armstrong officiated at the June 19, 1856, wedding of Emma Rooke and Alexander Liholiho in Kawaiahaʻo Church. Additionally, Armstrong served on the government Privy council and the House of Nobles.

The father of American education in Hawaii
Under  Kamehameha III, the position of Minister of Public Instruction of the Kingdom of Hawaii was created. On April 3, 1846, William Richards was appointed to fill the new position. When Richards died in 1847, Armstrong was appointed to fill the position. Armstrong held the position until 1855, when he became President of the Board of Education. The educational model he established in the kingdom earned Armstrong the sobriquet "The father of American education in Hawaii". He created a structured environment that was financially supported by a school tax. With Armstrong at the helm, curriculum was standardized, and the responsibilities of faith-based citizenship became a part of it. The kingdom's teachers were given extended training. Land grants were implemented for additional and improved facilities, and the kingdom began issuing its own textbooks. The public school system accommodated the majority of the students, but Armstrong also chartered private educational institutions.

Personal life and death
Richard Armstrong died September 23, 1860, following a riding accident which punctured an artery in his neck. He was buried on the grounds of Kawaiahaʻo Church.

He married Clarissa Chapman of Russell, Massachusetts. on September 5, 1831, in Bridgeport, Connecticut. She died July 20, 1891, in San Francisco, California. They had 10 children: Caroline Porter Armstrong Beckwith, William Nevins Armstrong I, William Nevins Armstrong, Mary Jane Graham Armstrong,. Richard Baxter Armstrong, Samuel Chapman Armstrong, Clarissa Hannah Armstrong Banning, Reuben Chapman Armstrong, Ellen Eliza Chapman Armstrong Weaver, and Amelia Hamilton Armstrong.

Notes

References

 - available at Project MUSE, subscription required

External links

1805 births
1860 deaths
American Presbyterian missionaries
Presbyterian missionaries in Hawaii
People from Northumberland County, Pennsylvania
People from Bridgeport, Connecticut
American expatriates in the Hawaiian Kingdom
Dickinson College alumni
Princeton Theological Seminary alumni
Accidental deaths in Hawaii
Deaths by horse-riding accident in the United States
Burials at Kawaiahaʻo Church
People from Wailuku, Hawaii
Protestant missionaries in French Polynesia

Richard Armstrong (Hawaii missionary)


Eanfrith (590–634) was briefly King of Bernicia from 633 to 634. His father was Æthelfrith, a Bernician king who had also ruled Deira to the south before being killed in battle around 616 against Raedwald of East Anglia, who had given refuge to Edwin, an exiled prince of Deira. His mother was Acha of Deira.

Edwin became king of Northumbria upon Æthelfrith's death, and Eanfrith, who was, according to Bede, the eldest of Æthelfrith's sons, went into exile to the north. In his Ecclesiastical History of the English People, Bede writes that "For all the time that Edwin reigned, the sons of the aforesaid Etheifrid [Æthelfrith], who had reigned before him, with many of the nobility, lived in banishment among the Scots or Picts, and were there instructed according to the doctrine of the Scots, and received the grace of baptism."

Eanfrith married a Pictish princess and had a son, Talorcan, who later became a king of the Picts (653–657). Edwin was killed by the army of Cadwallon ap Cadfan of Gwynedd and Penda of Mercia at the Battle of Hatfield Chase in October 633, and Eanfrith, taking the opportunity to return home, became king of Bernicia. He did not, however, rule Deira, which was held by a relative of Edwin, Osric. Bede tells us that as soon as Eanfrith became king, he "renounced and lost" his faith and returned to the "abominations" of his "former idols".

It is possible that Eanfrith was initially cooperative with Cadwallon. The historian D. P. Kirby, pointing to Eanfrith's evident ability to quickly exploit Edwin's death, has speculated that "a wide-ranging set of alliances" that included both Cadwallon and Eanfrith may have existed. If there was a friendly relationship between Eanfrith and Cadwallon at first, however, it must not have lasted, since Bede reports that Eanfrith went to Cadwallon "with only twelve chosen soldiers" in an attempt to negotiate peace, but Cadwallon had him killed.

The year in which he and Osric ruled was subsequently deemed so abhorrent because of their paganism that it was decided to add that year to the length of the reign of the Christian Oswald of Bernicia (Eanfrith's brother), who defeated Cadwallon and came to rule both Bernicia and Deira, so as to ignore the brief reigns of Eanfrith and Osric.

References

External links

590 births
630s deaths
Bernician monarchs
Anglo-Saxon pagans
7th-century English monarchs
Converts to Christianity from pagan religions
Converts to pagan religions from Christianity
Royal House of Northumbria
Idings

Eanfrith of Bernicia


The Separate Baptists are a group of Baptists originating in the 18th-century United States, primarily in the South, that grew out of the Great Awakening.

The Great Awakening was a religious revival and revitalization of piety among the Christian churches. It covered English-speaking countries and swept through the American colonies between the 1730s and the 1770s. Three important preachers of the times were Gilbert Tennent (1703–65), Jonathan Edwards (1703–58), and George Whitefield (1714–70). The Separate Baptists are most directly connected to Whitefield's influence. The first identifiable congregation of Separate Baptists was formed in Boston, Massachusetts. Whitefield preached in Boston in 1740. The pastor of the Baptist church disapproved of the revival excitement, while several members approved of it and became discontented with the pastor's ministry. They withdrew from the First Baptist Church and formed Second Baptist Church in 1743.

The Great Awakening served to both invigorate and divide churches. Many denominations divided into Old Lights — holding a low view of the revivalism, and sometimes directly opposing it — and New Lights — who enthusiastically embraced it. Many New Lights felt that the old ways had allowed too many unconverted church members, and by the end of the 1740s some of the New Lights believed the established churches could not be reformed from within and withdrew from them. A favorite verse among them was II Corinthians 6:17 — "Come out from among them, and be ye separate." This led to them being called Separate.

A growing body of Separate Baptists began in New England. They were zealous in evangelism and held to heart-felt religion. The most prominent New England pastor and congregation was Isaac Backus (1724–1808) and the church at Middleborough, Massachusetts. Backus was raised a Congregationalist and became a New Light (or Separatist) Congregational pastor in 1748. After conversion to Baptist views on the doctrine of baptism, Backus and others formed a Baptist congregation in 1756. Backus was very active in the fight for religious liberty in America. The Separate Baptists of New England were never truly a separate group from the Regular Baptists. It would remain for the Separate Baptists in the South to develop along distinct lines.

In 1745 Shubal Stearns (1706–71), a member of the Congregational church in Tolland, Connecticut, heard evangelist George Whitefield. Stearns was converted and adopted the Awakening's view of revival and conversion. Stearns' church became involved in a controversy over the proper subjects of baptism in 1751. Soon Stearns rejected infant baptism and sought baptism at the hands of Wait Palmer, Baptist minister of Stonington, Connecticut. By March, Shubal Stearns was ordained into the ministry by Palmer and Joshua Morse, the pastor of New London, Connecticut. The next twenty years of Stearns' remarkable ministry is inextricably intertwined with the rise and expansion of the Separate Baptists.

In 1754, Stearns moved south to Opequon, Virginia. Here he joined Daniel Marshall and wife Martha (Stearns' sister), who were already active in a Baptist church there. On November 22, 1755, Stearns and his party moved further south to Sandy Creek, in Guilford County, North Carolina. This party consisted of eight men and their wives, mostly relatives of Stearns. Stearns pastored at Sandy Creek until his death. From there, Separate Baptists spread in the South. The church quickly grew from 16 members to 606. Church members moved to other areas and started other churches. The Sandy Creek Association was formed in 1758. Morgan Edwards, Baptist minister and historian contemporary with Stearns, recorded that, "in 17 years, [Sandy Creek] has spread its branches westward as far as the great river Mississippi; southward as far as Georgia; eastward to the sea and Chesopeck [sic] Bay; and northward to the waters of the Pottowmack [sic]; it, in 17 years, is become mother, grandmother, and great grandmother to 42 churches, from which sprang 125 ministers."

For a time these Baptists remained somewhat distinct from the Regular Baptists. They were in the main in agreement with the Regulars, but holding to some minor points of difference. According to Edwards, "These are called Separates, not because they withdrew from the Regular-baptists but because they have hitherto declined any union with them. The faith and order of both are the same, except some trivial matters not sufficient to support a distinction, but less a disunion; for both avow the Century-Confession and the annexed discipline."

One distinction was in the number of ordinances or rites observed by the Separates. The nine rites were baptism, the Lord's supper, love feasts, laying on of hands, washing feet, anointing the sick, the right hand of fellowship, kiss of charity, and devoting children. Not all the churches practiced all nine of these, but most churches practiced more than the two ordinances generally held by the Regular Baptists — baptism and the Lord's supper.

With the exception of the Separate Baptists in Christ, the denominational name Separate Baptist disappeared in many areas of the country with the formal and informal agreements of union between the Regular Baptists and Separate Baptists, beginning in Virginia in 1787, in the Carolinas in 1789, and in Kentucky in 1797 & 1801. As recorded by Benedict, the conclusion of the terms of union in Virginia stated, "...we are united, and desire hereafter, that the names Regular and Separate be buried in oblivion; and that from henceforth, we shall be known by the name of the United Baptist Churches, in Virginia."

Descendants of the Separate Baptists include the Separate Baptists in Christ, Landmark Missionary Baptists, Primitive Baptists, Southern Baptists, United Baptists, and The General Association of Baptists.

Separate Baptists are particularly visible in Kentucky, where a member of the denomination, Vernie McGaha of Russell Springs, served in the state senate.

References
 .
 .
 .
 .
 .

Baptist denominations in North America
Former Christian denominations

Separate Baptists


Trench foot or fat foot is a medical condition that is caused by keeping feet in the cold, in dirty places, or in water for a long time. Trench foot was a big problem in the trenches of World War I. Many of the soldiers fighting got this condition.

The soldiers found it difficult to cope with the swelling wearing their boots but after realised that they could not get the boot on again as the foot had swollen to twice its size. Many men who suffered from it ending up having their feet amputated because they could not deal with the pain.

This can be treated by rubbing it to cause friction and if it is kept warm it can heal itself.

References

Diseases

Trench foot


A superlative, in grammar, is an adjective describing a noun that is the best example of a given quality. In other words, a superlative describes a noun that has more of some quality than any other.

Some examples:
the coldest day (i.e. the best example of a cold day, or the day that is colder than all the others)
the craziest man
the fluffiest cloud

In English, most superlatives can be formed by adding -EST to an existing adjective, like the examples above. (For adjectives that end in "-y", like "crazy", you often change the "y" to an "i" before you add the -EST on the end.)

Some adjectives have irregular superlative forms, which do not follow the rules, such as far ("farthest") and bad ("worst").

Other adjectives have no superlative form at all, and the superlative is made simply by adding the adverb "most" before the adjective. For instance, you do not say "funnest," or "interestingest". Instead, you say "most fun," and "most interesting."
This way of making the superlative is used for almost all adjectives ending in "ing" (like "interesting", "fascinating", "disgusting" or "appealing".)

Parts of speech
Grammar

Superlative


DCT is a digital recording component video videocassette format developed and introduced by Ampex in 1992.  It was based on the D1 format, and unlike the uncompressed recording scheme of D1, it was the first digital videotape format to use data compression.  Like D1 (and D2), it uses a similar cassette loaded with 3/4" (19mm) width tape.

One of the models of VCR released for the format was the Ampex DCT-1700D.

The type of data compression used by the format, discrete cosine transform (DCT), shares the same acronym as the format, but the meaning is different for the latter (the format's acronym meaning Data Component Technology).

DST (Data Storage Technology), a data-only version of DCT, was also developed by Ampex at the same time for the backup and archiving of data from servers and other enterprise-oriented IT systems.

References

External links
 Cutaway view of a DCT VCR
 Encyclopedia Pro's entry on DCT
 Ampex's History

Videocassette formats

DCT (videocassette format)


The Communist Workers Party of Russia - Revolutionary Party of Communists (RCWP-RPC) (Russian: Российская Коммунистическая Рабочая Партия – Революционная Партия Коммунистов)is a Communist political party in Russia. The party was created in October 2001, wanting to bring Communism and the Soviet Union back.

The RCWP-PRC is run by Viktor Tyulkin.

In the 1999 State Duma Election, the party got 1,481,890 votes overall. As of 2006, the party claims 55,000 members. The party also has no representatives in the State Duma or the Regional Parliaments.

Communist parties in Russia

Russian Communist Workers' Party – Revolutionary Party of Communists


Disney's Nine Old Men were a group of animators who were very important names for Disney. They made many important works of Disney, from Snow White and the Seven Dwarfs to The Fox and the Hound. Although the men of the group were all young, Walt Disney called them Nine Old Men as a reference to Franklin D. Roosevelt calling the US Supreme Court nine old men.

The Nine Old Men were:

Les Clark (November 17, 1907 - September 12, 1979), who joined Disney in 1927. He was best known for  animating Mickey Mouse as he was the only one of the Nine Old Men to work on that character from its start with Ub Iwerks. Les did many scenes throughout the years, animating up until Lady And The Tramp. He moved into directing and made many animated featurettes and shorts.

Ollie Johnston  (October 31, 1912 - April 14, 2008), who joined Disney in 1935, first worked on Snow White. He went on to write the animator's book The Illusion of Life with Frank Thomas. His work included Mr. Smee (in Peter Pan), the Stepsisters (in Cinderella), the District Attorney (in The Adventures of Ichabod and Mr. Toad), and Prince John (in Robin Hood). The book The Disney Villain, written by Johnston and Frank Thomas, says that Johnston also worked with Thomas on making characters such as Ichabod Crane (in The Adventures of Ichabod and Mr. Toad) and Sir Hiss (in Robin Hood).

Frank Thomas (September 5, 1912 - September 8, 2004) joined Disney in 1934. He went on to write the animator's book The Illusion of Life with Ollie Johnston. His work included the wicked Stepmother (in Cinderella), the Queen of Hearts (in Alice In Wonderland), and Captain Hook (in Peter Pan).

Wolfgang "Woolie" Reitherman  (June 26, 1909 - May 22, 1985) joined Disney in 1933 as an animator and director. He directed all the animated Disney movies after Walt's death until his retirement. Some of his work includes the Crocodile (in Peter Pan), the Dragon (in Sleeping Beauty), and the Rat (in Lady And The Tramp).

John Lounsbery  (March 9, 1911 - February 13, 1976) started in 1935 and, working with the name Norm 'Fergy' Ferguson, quickly became a star animator. Lounsbery, known as 'Louns' by the animators he worked with, was a strong draftsman whose work helped many animators over the years. His animation was noted for its squashy, stretchy feel. Lounsbery animated Ben Ali Gator in Fantasia; Father in Peter Pan; Tony, Joe, and some of the dogs in Lady And The Tramp; The Kings in Sleeping Beauty; The Elephants in The Jungle Book; and many, many others. In the 1970s, Louns became a Director and co-directed Winnie The Pooh And Tigger Too and his last movie, The Rescuers.

Eric Larson  (September 3, 1905 - October 25, 1988) joined in 1933. One of the top animators at Disney, he animated well known characters such as Peg in Lady And The Tramp; the Vultures in The Jungle Book; Peter Pan's flight over London to Neverland; and Brer Rabbit, Brer Fox, and Brer Bear (in Song of the South). Because of the way he could train new talent, Larson was given the job to spot and train new animators at Disney in the 1970s. Many of the top talents at Disney today were trained by Eric in the '70s and '80s.

Ward Kimball (March 4, 1914 - July 8, 2002) joined Disney in 1934. His work includes Lucifer, Jaq and Gus, (in Cinderella), and the Mad Hatter and Cheshire Cat (in Alice in Wonderland). His work was often more 'wild' than the other Disney animators and was very unique.

Milt Kahl (March 22, 1909 - April 19, 1987) started in 1934 working on Snow White. His work included Shere Khan (in The Jungle Book), Edgar the butler (in The Aristocats), the Sheriff of Nottingham (in Robin Hood), and Madame Medusa (in "The Rescuers").

Marc Davis (March 30, 1913 - January 12, 2000) started in 1935 on Snow White, and later he went on to work on the characters of Bambi and Thumper (in Bambi), Maleficent and the raven (in Sleeping Beauty), and Cruella DeVil (in One Hundred and One Dalmatians).  Davis also did character design for both the Pirates of the Caribbean and Haunted Mansion attractions at Disneyland.

By the time Robin Hood was released, only four of the Nine Old Men were still animating at Disney. They were Milt Kahl, John Lounsbery, Frank Thomas and Ollie Johnston, although Eric Larson and Wolfgang Reitherman were both working for Disney, but not as animators. Lounsbery died in 1976, Kahl retired the same year and died in 1987. Thomas and Johnston retired in 1978, and both later enjoyed cameo appearances in the Brad Bird-directed movies The Iron Giant (Warner Bros., 1999) and The Incredibles (Pixar, 2004).  Thomas died shortly after that, in 2004, leaving Johnston as the last living "Old Man."  He died on April 14, 2008.

References
Canemaker, John. (2001). Walt Disney's Nine Old Men and the Art of Animation. New York, NY: Disney Editions.  ISBN 0-7868-6496-6

Nine Old Men, Disney's

Disney's Nine Old Men


Thermodynamic entropy is a measure of how organized or disorganized energy is present in a system of atoms or molecules. It is measured in joules of energy per unit kelvin. Entropy is an important part of the third law of thermodynamics.

Imagine that a group of molecules has ten units of energy. If the energy in those molecules is perfectly organized, then the molecules can do ten units of work. However, if the energy became less organized (so, the entropy increased), the molecules might only be able to do six units of work, even though they still have ten units of energy in them.

When total entropy is reached, there is no more energy to spend. A good example of this is a cup of hot tea. The tea has a lot of energy compared to the room the tea is in. Over time the heat in the tea will spread into the room. The tea will become colder. This is because the energy (heat) in the tea moves to the surrounding area. Once the tea became cold, there is no more heat that can be spread. The tea has reached total entropy.

There are two types of these "rooms": An open system and a closed system. An open system means that energy (like heat) can freely flow in and out of the room. A closed system means that the room is closed off from the outside; no energy can go in or out.

In the case of the tea, the room was a closed system; no energy could enter it. But we can also make it an open system by placing a heater into the room. If we turn on the heater, we can use the heat from it to reheat the cup of tea. New energy has been brought into the room. The entropy has thus decreased. The heat that went from the heater into the tea can then move into the room again until total entropy has been reached. This is what the second law of thermodynamics is about.

A real life example of an open system is the Earth. It gets a lot of energy from the Sun every day. This allows plants to grow and water to stay liquid. If we took away the Sun, plants would die and water would freeze because the surface of our planet would be too cold.

Thermodynamics

Thermodynamic entropy


RAID is an acronym that stands for Redundant Array of Inexpensive Disks or  Redundant Array of Independent Disks. RAID is a term used in computing. With RAID, several hard disks are made into one logical disk. There are different ways this can be done. Each of the methods that puts the hard disks together has some benefits and drawbacks over using the drives as single disks, independent of each other. The main reasons why RAID is used are:

 To make the loss of data happen less often. This is done by having several copies of the data.
 To get more storage space by having many smaller disks.
 To get more flexibility (Disks can be changed or added while the system keeps running)
 To get the data more quickly.

It is not possible to achieve all of these goals at the same time, so choices need to be made.

There are also some bad things:

 Certain choices can protect against data being lost because one (or a number) of disks failed. They do not protect against the data being deleted or overwritten, though.
 In some configurations, RAID can tolerate that one or a number of disks fail. After the failed disks have been replaced, the data needs to be reconstructed. Depending on the configuration and the size of the disks, this reconstruction can take a long time.
 Certain kinds of errors will make it impossible to read the data

Most of the work on RAID is based on a paper written in 1988.

Companies have used RAID systems to store their data since the technology was made. There are different ways in which RAID systems can be made. Since its discovery, the cost of building a RAID system has come down a lot. For this reason, even some computers and appliances that are used at home have some RAID functions. Such systems can be used to store music or movies, for example.

Introduction

Difference between physical Disks and logical disks
A hard disk is a part of a computer. Normal hard disks use magnetism to store information. When hard disks are used, they are available to the operating system. In Microsoft Windows, each hard disk will get a drive letter (starting with C:, A: or B: are reserved for floppy drives). Unix and Linux-like operating systems have a single-rooted directory tree. This means that people who use the computers sometimes do not know where the information is stored.

In computing, the hard disks (which are hardware, and can be touched) are sometimes called physical drives or physical disks. What the operating system shows the user is sometimes called logical disk. A physical drive can be split into different sections, called disk partitions. Usually, each disk partition contains one file system. The operating system will show each partition like a logical disk.

Therefore, to the user, both the setup with many physical disks and the setup with many logical disks will look the same. The user cannot decide if a "logical disk" is the same as a physical disk, or if it simply is a part of the disk. Storage Area Networks (SANs) completely change this view. All that is visible of a SAN is a number of logical disks.

Reading and writing data
In the computer, data is organised in the form of bits and bytes. In most systems, 8 bits make up a byte. Computer memory uses electricity to store the data, hard disks use magnetism. Therefore, when data is written on a disk, the electric signal is converted into a magnetic one. When data is read from disk, the conversion is done in the other direction: An electrical signal is made from the polarity of a magnetic field.

What is RAID?
A RAID array joins two or more hard disks so that they make a logical disk. There are different reasons why this is done. The most common ones are:

 Stopping data loss, when one or more disks of the array fail.
 Getting faster data transfers.
 Getting the ability to change disks while the system keeps running.
 Joining several disks to get more storage capacity; sometimes lots of cheap disks are used, rather than a more expensive one.

RAID is done by  using special hardware  or software on the computer. The joined hard disks will then look like one hard disk to the user. Most RAID levels increase the redundancy. This means that they store the data more often, or they store information on how to reconstruct the data. This allows for a number of disks to fail without the data being lost. When the failed disk is replaced, the data it should contain will be copied or rebuilt from the other disks of the system. This can take a long time. The time it takes depends on different factors, like the size of the array.

Why use RAID?
One of the reasons why many companies are using RAID is that the data in the array can simply be used. Those using the data need not be aware they are using RAID at all. When a failure occurred and the array is recovering, access to the data will be slower. Accessing the data during this time will also slow down the recovery process, but this is still much faster than not being able to work with the data at all.
Depending on the RAID level however, disks may not fail while the new disk is being prepared for use. A disk failing at that time will result in losing all the data in the array.

The different ways to join disks are called RAID levels. A bigger number for the level is not necessarily better. Different RAID levels have different purposes. Some RAID levels need special disks and special controllers.

History
In 1978, a man called Norman Ken Ouchi, who worked at IBM, made a suggestion describing the plans for what would later become RAID 5. The plans also described something similar to RAID 1, as well as the protection of a part of RAID 4.

Workers at the University of Berkeley helped to plan out research in 1987. They were trying to make it possible for RAID technology to recognize two hard drives instead of one. They found that when RAID technology had two hard drives, it had much better storage than with only one hard drive. However, it crashed much more often.

In 1988, the different types of RAID (1 to 5), were written about by David Patterson, Garth Gibson and Randy Katz in their article, called "A Case for Redundant Arrays of Inexpensive Disks (RAID)". This article was the first to call the new technology RAID and the name became official.

Basic concepts used by RAID systems
RAID uses a few basic ideas, which were described in the article "RAID: High-Performance, Reliable Secondary Storage" by Peter Chen and others, published in 1994.

Caching
Caching is a technology that also has its uses in RAID systems. There are different kinds of caches that are used in RAID systems:

 Operating system
 RAID controller
 Enterprise disk array

In modern systems, a write request is shown as done when the data has been written to the cache. This does not mean that the data has been written to the disk. Requests from the cache are not necessarily handled in the same order that they were written to the cache. This makes it possible that, if the system fails, sometimes some data has not been written to the disk involved. For this reason, many systems have a cache that is backed by a battery.

Mirroring: More than one copy of the data
When talking about a mirror, this is a very simple idea. Instead of the data being in only one place, there are several copies of the data. These copies usually are on different hard disks (or disk partitions). If there are two copies, one of them can fail without the data being affected (as it still is on the other copy). Mirroring can also give a boost when reading data. It will always be taken from the fastest disk that responds. Writing data is slower though, because all disks need to be updated.

Striping: Part of the data is on another disk
With striping, the data is split into different parts. These parts then end up on different disks (or disk partitions). This means that writing data is faster, as it can be done in parallel. This does not mean that there will not be faults, as each block of data is only found on one disk.

Error correction and faults
It is possible to calculate different kinds of checksums. Some methods of calculating checksums allow finding a mistake. Most RAID levels that use redundancy can do this. Some methods are more difficult to do, but they allow to not only detect the error, but to fix it.

Hot spares: using more disks than needed
Many of the ways to have RAID support something is called a hot spare. A hot spare is an empty disk that is not used in normal operation. When a disk fails, data can directly be copied onto the hot spare disk. That way, the failed disk needs to be replaced by a new empty drive to become the hot spare.

Stripe size and chunk size: spreading the data over several disks
RAID works by spreading the data over several disks. Two of the terms often used in this context are stripe size and chunk size.

The chunk size is the smallest data block that is written to a single disk of the array. The stripe size is the size of a block of data that will be spread over all disks. That way, with four disks, and a stripe size of 64 kilobytes (kB), 16 kB will be written to each disk. The chunk size in this example is therefore 16 kB. Making the stripe size bigger will mean a faster data transfer rate, but also a bigger maximum latency. In this case, this is the time needed to get a block of data.

Putting disk together: JBOD, concatenation or spanning

Many controllers (and also software) can put disks together in the following way: Take the first disk, till it ends, then they take the second,  and so on. In that way, several smaller disks look like a larger one. This is not really RAID, as there is no redundancy. Also, spanning can combine disks where RAID 0 cannot do anything. Generally, this is called just a bunch of disks (JBOD).

This is like a distant relative of RAID because the logical drive is made of different physical drives. Concatenation is sometimes used to turn several small drives into one larger useful drive. This can not be done with RAID 0.  For example, JBOD could combine 3 GB, 15 GB, 5.5 GB, and 12 GB drives into a logical drive at 35.5 GB, which is often more useful than the drives alone.

In the diagram to the right, data are concatenated from the end of disk 0 (block A63) to the beginning of disk 1 (block A64); end of disk 1 (block A91) to the beginning of disk 2 (block A92).
If RAID 0 were used, then disk 0 and disk 2 would be truncated to 28 blocks, the size of the smallest disk in the array (disk 1) for a total size of 84 blocks.

Some RAID controllers use JBOD to talk about working on drives without RAID features. Each drive shows up separately in the operating system. This JBOD is not the same as concatenation.

Many Linux systems use the terms "linear mode" or "append mode". The Mac OS X 10.4 implementation — called a "Concatenated Disk Set" — does not leave the user with any usable data on the remaining drives if one drive fails in a concatenated disk set, although the disks otherwise operate as described above.

Concatenation is one of the uses of the Logical Volume Manager in Linux. It can be used to create virtual drives.

Drive Clone
Most modern hard disks have a standard called Self-Monitoring, Analysis and Reporting Technology (S.M.A.R.T). SMART allows to monitor certain things on a hard disk drive. Certain controllers allow to replace a single hard disk even before it fails, for example because S.M.A.R.T or another disk test reports too many correctable errors. To do this, the controller will copy all the data onto a hot spare drive. After this, the disk can be replaced by another (which will simply become the new hot spare).

Different setups
The setup of the disks and how they use the techniques above affects the performance and reliability of the system. When more disks are used, one of the disks is more likely to fail. Because of this, mechanisms have to be built to be able to find and fix errors. This makes the whole system more reliable, as it is able to survive and repair the failure.

Basics: simple RAID levels

RAID levels in common use

RAID 0 "striping"
RAID 0 is not really RAID because it is not redundant. With RAID 0, disks are simply put together to make a large disk. This is called "striping". When one disk fails, the whole array fails. Therefore, RAID 0 is rarely used for important data, but reading and writing data from the disk can be faster with striping because each disk reads part of the file at the same time.

With RAID 0, disk blocks that come after one another are usually placed on different disks. For this reason, all disks used by a RAID 0 should be the same size.

RAID 0 is often used for Swapspace on Linux or Unix-like operating systems.

RAID 1 "mirroring"
With RAID 1, two disks are put together. Both hold the same data, one is "mirroring" the other. This is easy, fast configuration  whether implemented with a hardware controller or by software.

RAID 5 "striping with distributed parity"
RAID Level 5 is what is probably used most of the time. At least three hard disks are needed to build a RAID 5 storage array. Each block of data will be stored in three different places. Two of these places will store the block as it is, the third will store a checksum. This checksum is a special case of a Reed-Solomon code that only uses bitwise addition. Usually, it is  calculated using the XOR method. Since this method is symmetric, one lost data block can be rebuilt from the other data block and the checksum. For each block, a different disk will hold the parity block which holds the checksum. This is done to increase redundancy. Any disk can fail. Overall, there will be one disk holding the checksums, so the total usable capacity will be that of all disks except for one. The size of the resulting logical disk will be the size of all disks together, except for one disk which holds parity information.

Of course this is slower than RAID level 1, since on every write, all disks need to be read to calculate and update the parity information. The read performance of RAID 5 is almost as good as RAID 0 for the same number of disks. Except for the parity blocks, the distribution of data over the drives follows the same pattern as RAID 0. The reason RAID 5 is slightly slower is that the disks must skip over the parity blocks.

A RAID 5 with a failed disk will continue to work. It is in degraded mode. A degraded RAID 5 can be very slow. For this reason an additional disk is often added. This is called hot spare disk. If a disk fails, the data can be directly rebuilt onto the extra disk. RAID 5 can also be done in software quite easily.

Mainly because of performance problems of failed RAID 5 arrays, some database experts have formed a group called BAARF—the Battle Against Any Raid Five.

If the system fails while there are active writes, the parity of a stripe may become inconsistent with the data. If this is not repaired before a disk or block fails, data loss may occur. An incorrect parity will be used to reconstruct the missing block in that stripe. This problem is sometimes known as the "write hole". Battery-backed caches and similar techniques are commonly used to reduce the chance for this to occur.

Pictures

RAID levels used less

RAID 2
This was used with very large computers. Special expensive disks and a special controller are needed to use RAID Level 2. The data is distributed at the bit-level (all other levels use byte-level actions). Special calculations are done. Data is split up into static sequences of bits. 8 data bits and 2 parity bits are put together. Then a Hamming code is calculated. The fragments of the Hamming code are then distributed over the different disks.

RAID 2 is the only RAID level that can repair errors, the other RAID levels can only detect them. When they find that the information needed does not make sense, they will simply rebuild it. This is done with calculations, using information on the other disks. If that information is missing or wrong, they cannot do much. Because it uses Hamming codes, RAID 2 can find out which piece of the information is wrong, and correct only that piece.

RAID 2 needs at least 10 disks to work. Because of its complexity and its need for very expensive and special hardware, RAID 2 is no longer used very much.

RAID 3 "striping with dedicated parity"
Raid Level 3 is much like RAID Level 0. An additional disk is added to store parity information. This is done by bitwise addition of the value of a block on the other disks. The parity information is stored on a separate (dedicated) disk. This is not good, because if the parity disk crashes, the parity information is lost.

RAID Level 3 is usually done with at least 3 disks. A two-disk setup is identical to a RAID Level 0.

RAID 4 "striping with dedicated parity"
This is very similar to RAID 3, except that the parity information is calculated over larger blocks, and not single bytes. This is like RAID 5. At least three disks are needed for a RAID 4 array.

RAID 6
RAID level 6 was not an original RAID level. It adds an additional parity block to a RAID 5 array. It needs at least four disks (two disks for the capacity, two disks for redundancy). RAID 5 can be seen as a special case of a Reed-Solomon code. RAID 5 is a special case, though, it only needs addition in the Galois field GF(2). This is easy to do with XORs. RAID 6 extends these calculations. It is no longer a special case, and all of the calculations need to be done. With RAID 6, an extra checksum (called polynomial) is used, usually of GF (28). With this approach it is possible to protect against any number of failed disks. RAID 6 is for the case of using two checksums to protect against the loss of two disks.

Like with RAID 5, parity and data are on different disks for each block. The two parity blocks are also located on different disks.

There are different ways to do RAID 6. They are different in their write performance, and in how much calculations are needed. Being able to do faster writes usually means more calculations are needed.

RAID 6 is slower than RAID 5, but it allows the RAID to continue with any two disks failed. RAID 6 is becoming popular because it allows an array to be rebuilt after a single-drive failure even if one of the remaining disks has one or more bad sectors.

Pictures

Non-standard RAID levels

Double parity / Diagonal parity
RAID 6 uses two parity blocks. These are calculated in a special way over a polynomial. Double parity RAID (also called diagonal parity RAID) uses a different polynomial for each of these parity blocks. Recently, the industry association that defined RAID said that double parity RAID is a different form of RAID 6.

RAID-DP
RAID-DP is another way of having double parity.

RAID 1.5
RAID 1.5 (not to be confused with RAID 15, which is different) is a proprietary RAID implementation. Like RAID 1, it only uses two disks, but it does both striping and mirroring (similar to RAID 10). Most things are done in hardware.

RAID 5E, RAID 5EE and RAID 6E
RAID 5E, RAID 5EE and RAID 6E (with the added E for Enhanced) generally refer to different types of RAID 5 or RAID 6 with a hot spare. With these implementations, the hot spare drive is not a physical drive. Rather, it exists in the form of free space on the disks. This increases performance, but it means that a hot spare cannot be shared between different arrays. The scheme was introduced by IBM ServeRAID around 2001.

RAID 7
This is a proprietary implementation. It adds caching to a RAID 3 or RAID 4 array.

Intel Matrix RAID
Some Intel main boards have RAID chip that have this feature. It uses two or three disks, and then partitions them equally to form a combination of RAID 0, RAID 1, RAID 5 or RAID 1+0 levels.

Linux MD RAID driver
This is the name for the driver that allows to do software RAID with Linux. In addition to the normal RAID levels 0-6, it also has a RAID 10 implementation. Since Kernel 2.6.9, RAID 10 is a single level. The implementation has some non-standard features.

RAID Z
Sun has implemented a file system called ZFS. This file system is optimised for handling large amounts of data. It includes a Logical Volume Manager. It also includes a feature called RAID-Z. It avoids the problem called RAID 5 write hole  because it has a copy-on-write policy: It does not overwrite the data directly, but writes new data in a new location on the disk. When the write was successful, the old data is deleted. It avoids the need for read-modify-write operations for small writes, because it only writes full-stripes. Small blocks are mirrored instead of parity protected, which is possible because the file system knows the way the storage is organised. It can therefore allocate extra space if necessary. There is also RAID-Z2 which uses two forms of parity to achieve results similar to RAID 6: the ability to survive up to two drive failures without losing data.

Pictures

Joining RAID levels
With RAID different disks can be put together to get a logical disk.The user will only see the logical disk. Each one of the RAID levels mentioned above has good and bad points. But RAID can also work with logical disks. That way one of the RAID levels above can be used with a set of logical disks. Many people note it by writing the numbers together. Sometimes, they write a '+' or an '&' in between. Common combinations (using two levels) are the following:

 RAID 0+1: Two or more RAID 0 arrays are combined to a RAID 1 array; This is called a Mirror of stripes
 RAID 1+0: Same as RAID 0+1, but RAID levels reversed; Stripe of Mirrors. This makes disk failure rarer than RAID 0+1 above.
 RAID 5+0: Stripe several RAID 5's with a RAID 0. One disk of each RAID 5 can fail, but makes that RAID 5 the single point of failure; if another disk of that array fails, all the data of the array will be lost.
 RAID 5+1: Mirror a set of RAID 5: In a situations where the RAID is made of six disks, any three can fail (without data being lost).
 RAID 6+0: Stripe several RAID 6 arrays over a RAID 0; Two disks of each RAID 6 can fail without data loss.

With six disks of 300 GB each, a total capacity of 1.8TB, it is possible to make a RAID 5, with 1.5 TB usable space. In that array, one disk can fail without data loss. With RAID 50, the space is reduced to 1.2 TB, but one disk of each RAID 5 can fail, plus there is a noticeable increase in performance. RAID 51 reduces the usable size to 900 GB, but allows any three drives to fail.

Making a RAID
There are different ways to make a RAID. It can either be done with software, or with hardware.

Software RAID
A  RAID can be made with software in two different ways. In the case of Software RAID, the disks are connected like normal hard disks. It is the computer that makes the RAID work. This means that for each access the CPU also needs to do the calculations for the RAID. The calculations for RAID 0 or RAID 1 are simple. However, the calculations for  RAID 5, RAID 6, or one of the combined RAID levels can be a lot of work. In a software RAID, automatically booting from an array that failed may be a difficult thing to do. Finally, the way RAID is done in software depends on the operating system used; it is generally not possible to re-build a Software RAID array with a different operating system. Operating systems usually use hard disk partitions rather than whole hard disks to make RAID arrays.

Hardware RAID
A RAID can also be made with hardware. In this case, a special disk controller is used; this controller card hides the fact that it is doing RAID from the operating system and the user. The calculations of checksum information, and other RAID-related calculations are done on a special microchip in that controller. This makes the RAID independent of the operating system. The operating system will not see the RAID, it will see a single disk. Different manufacturers do RAID in different ways. This means that a RAID built with one hardware RAID controller cannot be rebuilt by another RAID controller of a different manufacturer. Hardware RAID controllers are often expensive to buy.

Hardware-assisted RAID
This is a mix between hardware RAID and software RAID. Hardware-assisted RAID uses a special controller chip (like hardware RAID), but this chip can not do many operations. It is only active when the system is started; as soon as the operating system is fully loaded, this configuration is like software RAID. Some motherboards have RAID functions for the disks attached; most often, these RAID functions are done as hardware-assisted RAID. This means that special software is needed to be able to use these RAID functions and to be able to recover from a failed disk.

Different terms related to hardware failures
There are different terms that are used when talking about hardware failures:

Failure rate
The failure rate is how often a system fails. The mean time to failure (MTTF) or mean time between  failures (MTBF) of a RAID system is the same as that of its components. A RAID system cannot protect against failures of its individual hard drives, after all. The more complicated types of RAID (anything beyond "striping" or "concatenation") can help keep the data intact even if an individual hard drive fails, though.

Mean time to data loss
The mean time to data loss (MTTDL) gives the average time before a loss of data happens in a given array.  Mean time to data loss of a given RAID may be higher or lower than that of its hard disks. This depends on the type of RAID used.

Mean time to recovery
Arrays that have redundancy can recover from some failures. The mean time to recovery shows how long it takes until a failed array is back to its normal state. This adds both the time to replace a failed disk mechanism as well as time to re-build the array (i.e. to replicate data for redundancy).

Unrecoverable bit error rate
The unrecoverable bit error rate (UBE) tells how long a disk drive will be unable to recover data after using cyclic redundancy check (CRC) codes and multiple retries.

Problems with RAID
There are also certain problems with the ideas or the technology behind RAID:

Adding disks at a later time
Certain RAID levels allow to extend the array by simply adding hard disks, at a later time. Information such as parity blocks is often scattered on several disks. Adding a disk to the array means that a reorganisation becomes necessary. Such a reorganisation is like a re-build of the array, it can take a long time. When this is done, the additional space may not be available yet, because both the file system on the array, and the operating system need to be told about it. Some file systems do not support to be grown after they have been created. In such a case, all the data needs to be backed up, the array needs be re-created with the new layout, and the data needs to be restored onto it.

Another option to add storage is to create a new array, and to let a logical volume manager handle the situation. This allows to grow almost any RAID system, even RAID1 (which by itself is limited to two disks).

Linked failures
The error correction mechanism in RAID assumes that failures of drives are independent. It is possible to calculate how often a piece of equipment can fail and to arrange the array to make data loss very improbable.

In practice, however, the drives were often bought together. They have roughly the same age, and have been used similarly (called wear). Many drives fail because of mechanical problems. The older a drive is, the more worn are its mechanical parts. Mechanical parts that are old are more likely to fail than those that are younger. This means that drive failures are no longer statistically independent. In practice, there is a chance that a second disk will also fail before the first has been recovered. This means that data loss can occur at significant rates, in practice.

Atomicity
Another problem that also occurs with RAID systems is that applications expect what is called Atomicity: Either all of the data is written, or none is. Writing the data is known as a transaction.

In RAID arrays, the new data is usually written in the place where the old data was. This has become known as update in-place. Jim Gray, a database researcher wrote a paper in 1981 where he described this problem.

Very few storage systems allow atomic write semantics. When an object is written to disk, a RAID storage device will usually be writing all copies of the object in parallel. Very often, there is only one processor responsible for writing the data. In such a case, the writes of data to the different drives will overlap. This is known as overlapped write or staggered write. An error that occurs during the process of writing may therefore leave the redundant copies in different states. What is worse, it may leave the copies in neither the old nor the new state. Logging relies on the original data being either in the old or the new state, though. This permits backing out the logical change, but few storage systems provide an atomic write semantic on a RAID disk.

Using a battery-backed write cache can solve this problem, but only in a power failure scenario.

Transactional support is not present in all hardware RAID controllers. Therefore, many operating systems include it to protect against data loss during an interrupted write. Novell Netware, starting with version 3.x, included a transaction tracking system. Microsoft introduced transaction tracking via the journaling feature in NTFS. NetApp WAFL file system solves it by never updating the data in place, as does ZFS.

Unrecoverable data
Some sectors on a hard disk may have become unreadable because of a mistake. Some RAID implementations can deal with this situation by moving the data elsewhere and marking the sector on the disk as bad. This happens at about 1 bit in 1015 in enterprise-class disk drives, and 1 bit in 1014 in ordinary disk drives. Disk capacities are steadily increasing. This may mean that sometimes, a RAID cannot be rebuilt, because such an error is found when the array is rebuilt after a disk failure. Certain technologies such as RAID 6 try to address this issue, but they suffer from a very high write penalty, in other words writing data becomes very slow.

Write cache reliability
The disk system can acknowledge the write operation as soon as the data is in the cache. It does not need to wait until the data has been physically written. However, any power outage can then mean a significant data loss of any data queued in such a cache.

With hardware RAID, a battery can be used to protect this cache. This often solves the problem. When the power fails, the controller can finish writing the cache when the power is back. This solution can still fail, though: the battery may have worn out, the power may have been off for too long, the disks could be moved to another controller, the controller itself could fail. Certain systems can do periodic battery checks, but these use the battery itself, and leave it in a state where it is not fully charged.

Equipment compatibility
The disk formats on different RAID controllers are not necessarily compatible. Therefore, it may not be possible to read a RAID array on different hardware. Consequently, a non-disk hardware failure may require using identical hardware, or a backup, to recover the data.

What RAID can and cannot do
This guide was taken from a thread in a RAID-related forum. This was done to help point out the advantages and disadvantages of choosing RAID. It is directed at people who want to choose RAID for either increases in performance or redundancy. It contains links to other threads in its forum containing user-generated anecdotal reviews of their RAID experiences.

What RAID can do
 RAID can protect uptime. RAID levels 1, 0+1/10, 5 and 6 (and their variants such as 50 and 51) make up for a mechanical hard disk failure. Even after the disk failed, the data on the array can still be used. Instead of a time consuming restore from tape, DVD or other slow backup media, RAID allows data to be restored to a replacement disk from the other members of the array. During this restoration process, it is available to users in a degraded state. This is very important to enterprises, as downtime quickly leads to lost earning power. For home users, it can protect uptime of large media storage arrays, which would require time consuming restoration from dozens of DVD or quite a few tapes in the event of a disk failing that is not protected by redundancy.
 RAID can increase performance in certain applications. RAID levels 0, 5 and 6 all use striping. This allows multiple spindles to increase transfer rates for linear transfers. Workstation-type applications often work with large files. They greatly  benefit from disk striping. Examples for such applications are those using video or audio files. This throughput is also useful in disk-to-disk backups. RAID 1 as well as other striping-based RAID levels can improve the performance for access patterns with many simultaneous random accesses, like those used by a multi-user database.

What RAID cannot do
 RAID cannot protect the data on the array. A RAID array has one file system. This creates a single point of failure. There are many things that can happen to this file system other than physical disk failure. RAID cannot defend against these sources of data loss. RAID will not stop a virus from destroying data. RAID will not prevent corruption. RAID will not save data when a user modifies it or deletes it by accident. RAID does not protect data from hardware failure of any component besides physical disks. RAID does not protect data from natural or man made disasters such as fires and floods. To protect data, it must be backed up to removable media, such as DVD, tape, or an external hard disk. The backup must be kept in a different place. RAID alone will not prevent a disaster, when (not if) it occurs, from turning into data loss. Disasters cannot be prevented, but backups allow data loss to be prevented.
 RAID cannot simplify disaster recovery. When running a single disk, the disk can be used by most operating systems as they come with a common device driver. However, most RAID controllers need special drivers. Recovery tools that work with single disks on generic controllers will require special drivers to access data on RAID arrays. If these recovery tools are poorly coded and do not allow providing for additional drivers, then a RAID array will probably be inaccessible to that recovery tool.
 RAID cannot provide a performance boost in all applications. This statement is especially true with typical desktop application users and gamers. For most desktop applications and games the buffer strategy and seek performance of the disk(s) are more important than raw throughput. Increasing raw sustained transfer rate shows little gains for such users, as most files that they access are typically very small anyway. Disk striping using RAID 0 increases linear transfer performance, not buffer and seek performance. As a result, disk striping using RAID 0 shows little to no performance gain in most desktop applications and games, although there are exceptions. For desktop users and gamers with high performance as a goal, it is better to buy a faster, bigger, and more expensive single disk than it is to run two slower/smaller drives in RAID 0. Even running the latest, greatest, and biggest drives in RAID-0 is unlikely to boost performance more than 10%, and performance may drop in some access patterns, particularly games.
 It is difficult to move RAID to a new system. With a single disk, it is relatively easy to move the disk to a new system. It can simply be connected to the new system, if it has the same interface available. However, this is not so easy with a RAID array. There is a certain kind of Metadata that says how the RAID is set up. A RAID BIOS must be able to read this metadata so that it can successfully construct the array and make it accessible to an operating system. Since RAID controller makers use different formats for their metadata (even controllers of different families from the same manufacturer may use incompatible metadata formats) it is almost impossible to move a RAID array to a different controller. When moving a RAID array to a new system, plans should be made to move the controller as well. With the popularity of motherboard integrated RAID controllers, this is extremely difficult. Generally, it is possible to move the RAID array members and controllers together. Software RAID in Linux and Windows Server Products can also work around this limitation, but software RAID has others (mostly performance related).

Example
The RAID levels used most often are RAID 0, RAID 1, and RAID 5. Suppose there is a 3 disk setup, with 3 identical disks of 1 TB each, and  the probability of failure of a drive for a given timespan is 1%.

References

Other websites

 RAID 6 tutorial
 Working RAID pictures
 RAID Levels — Tutorial and Diagrams
 Animations to learn about RAID Levels 0, 1, 5, 10, and 50

Storage devices

RAID


Woodrow Wilson Guthrie, better known as Woody Guthrie (July 14, 1912 – October 3, 1967), was an American folk musician and songwriter, of the 20th century.

Early life
Guthrie was born Woodrow Wilson Guthrie in Okemah, Oklahoma. He was named after President Woodrow Wilson.

Career
Guthrie wrote over a thousand songs during his career. His more famous songs include "This Land Is Your Land", "Mail Myself To You", "This Train", "Bound For Glory", and "Hobo's Lullaby". One of his most famous albums was titled Dust Bowl Ballads. He sang about the Great Depression, and the problems faced by farmers at the time of the Dust Bowl, when erosion and drought ruined millions of acres of farmland.

Guthrie recorded a series of songs for the United States government, about sexually transmitted diseases, that served as warnings to the public. Much of the time he appeared opposed to governments as he saw them, and also politics. Guthrie identified strongly with the Industrial Workers of the World, called the "Wobblies", and also the Communist Party, but he never joined either one. His songs, and his interpretations of older songs, spoke to people of many different beliefs. Many of his songs used old tunes, that he gave new words.

The composer names of most folk songs are lost to history, or their songs have been adapted so many times that they completely change form. Even though Guthrie and his songs were well-known, they came to be accepted as genuine folk songs. They appeared in songbooks, and were performed and recorded by many different artists, and also sung by amateurs and families at home. Guthrie worked with or influenced many later musicians.

Illness from Huntington's disease
Guthrie's career was cut short by the illness Huntington's disease. By the late 1940s, Guthrie's health was getting poor, and his behavior was getting very erratic. He had gotten various diagnoses (including alcoholism and schizophrenia), but in 1952, it was determined that he was dying from Huntington's disease, He inherited it from his mother. Worrying that he was a danger to their children, his wife, Marjorie, said he needed to go back to California without her. They finally divorced.  Over a long period of time, the illness left him in a wheelchair, then finally unable to get out of bed, or even hold a guitar.

He spent many years in a hospital, visited by his family and friends. Folk musician Pete Seeger was a regular visitor. One day, the young Bob Dylan came to visit Guthrie. He had hitchhiked from Minnesota to New York, to meet Guthrie. He played Guthrie "A Song to Woody", which he had written as a tribute. Guthrie liked Dylan, and invited him back. Dylan stayed with the Guthrie family, and became friends with thirteen-year-old Arlo Guthrie, who also became a musician.

Death and legacy
Guthrie died in 1967, from the effects of Huntington's disease in New York City, aged 55. There have been many tributes made to Guthrie and his music through the years. Actor David Carradine played him in the movie Bound for Glory. Guthrie's songs are still sung today, and are a symbol of American life.

Related pages
List of country musicians from Oklahoma

References

Other websites

 The Woody Guthrie Center
 The Woody Guthrie Foundation and Archives
 Woody Guthrie and the Archive of American Folk Song: Correspondence, 1940–1950, Library of Congress, American Folklife Center. "American Memory" presentation of archival correspondence written by Woody Guthrie to the staff of the Archive of American Folk Song. Retrieved 14 June 2015
 Songfacts interview with Anna Canoni (Guthrie's granddaughter)
 Woody Guthrie at Find a Grave

Voices of Oklahoma interview with Mary Jo Guthrie. First person interview conducted on May 9, 2013 with Mary Jo Guthrie talking about her brother Woody Guthrie. Original audio and transcript archived with Voices of Oklahoma oral history project.

Deaths from Huntington's disease
American folk musicians
American singer-songwriters
American guitarists
Industrial Workers of the World
Musicians from Oklahoma
1912 births
1967 deaths

Woody Guthrie


Muscle atrophy or "muscle wastage" is a medical problem where a person loses muscle tissue.  This makes the person's muscles weaker.  With muscle atrophy, muscles can waste away completely, or only partly.

Many older people have muscular atrophy. Muscle atrophy can also happen to people with certain diseases or medical conditions, like cancer, AIDS, congestive heart failure, Chronic obstructive pulmonary disease, and renal failure (where the kidneys do not work correctly).  Muscles can atrophy (or get smaller and weaker) when those muscles are not used as much as usual - for example, when a person has to wear a cast for a broken arm or leg, or when a person must be on bed rest for a long time during a long illness.  Muscle atrophy can also be caused by Dejerine Sottas syndrome, cachexia, burns, liver failure, and starvation.

Muscular atrophy can cause serious problems in a person's life.  As the person loses muscle strength, he will lose the ability to do more and more things.  When he tries to do things, he will be more likely to have accidents.  Muscular atrophy also increases the risks of falling among people with certain medical conditions, such as IBM (inclusion body myositis).

No one knows exactly what causes muscular atrophy. It may be due to the gradual failure in the "satellite cells" which help to regenerate skeletal muscle fibres, and a decrease in sensitivity to or the availability of secreted growth factors which are necessary to maintain muscle mass and satellite cell survival.

In muscle atrophy, the normal balance between protein synthesis and protein degradation changes.  There is a down-regulation of protein synthesis pathways, and an activation of protein breakdown pathways.
In the ATP-dependent ubiquitin/proteasome pathway,  particular proteins are targeted for destruction by the ligation of at least four copies of a small peptide called ubiquitin onto a substrate protein. The substrate is later targeted for destruction by the proteasome.

Muscle atrophy can be treated
 by exercise which induces an increase in muscle mass. The exercise downregulates the pathways which induce muscle hypertrophy, or an increase in muscle size.
 by the use of functional electrical stimulation to stimulate the muscles. This has seen a large amount of success in the rehabilitation of paraplegic patients.
 by therapy with muscle-building amino acids for regenerating damaged or atrophied muscle tissue. The branched-chain amino acids or BCAAs (leucine, isoleucine, and valine) are critical to this process, in addition to lysine and other amino acids.

References

Physiology
Muscle diseases

Muscle atrophy


The mass-to-charge ratio is a physical quantity (it is an amount that can be measured). The SI unit is kg/C, which is kilograms divided by the coulomb. Sometimes the charge-to-mass ratio is used instead.

In a vacuum, all particles with the same mass-to-charge ratio move in the same path, when in the same strength of electric and magnetic fields.

It is important for things like mass spectrometry.

Basic physics ideas
Mass spectrometry

Mass-to-charge ratio