title: Chrysler 300 letter series

text: The 300 letter series name was resurrected in 1999 on the Chrysler 300M; but it is the 2005 300C that is closest to the original with its rear-wheel drive, and V8 engine once again bearing the "Hemi" name.


title: Quincy, Illinois

text: Quincy ( ), known as Illinois's "Gem City", is a city in and the county seat of Adams County, Illinois, United States, located on the Mississippi River. The 2020 census counted a population of 39,463 in the city itself, down from 40,633 in 2010. As of July 1, 2015, the Quincy Micro Area had an estimated population of 77,220. During the 19th century, Quincy was a thriving transportation center as riverboats and rail service linked the city to many destinations west and along the river. It was Illinois' second-largest city, surpassing Peoria in 1870. The city has several historic districts, including the Downtown Quincy Historic District and the South Side German Historic District, which display the architecture of Quincy's many German immigrants from the late 19th century.


title: Quincy, Illinois

text: Quincy's location along the Mississippi River has attracted settlers for centuries. The French became the first European presence to colonize the region, after Louis Jolliet, Jacques Marquette, Jamison Knapp and the La Salle Expeditions explored the Upper Mississippi River Valley. Fur goods became a valuable commodity of the region, and European explorers and merchants alike were attracted to the prospects of the growing fur trade of the North American frontier. The Mississippi River, acting as a superhighway for transporting goods downstream, became the area's most vital transportation asset.


title: Quincy, Illinois

text: Following the events of the Seven Years' War, which ended in 1763, Great Britain took control of New France, including that of the Illinois Territory. The Illinois Territory changed hands again a few decades later during the American Revolutionary War.


title: Quincy, Illinois

text: After the War of 1812, the American government granted military tracts to veterans as a means to help populate the West. Peter Flinn, having acquired the land from veteran Mark McGowan for his military service in 1819, ended up selling of land acquisitions to Moravia, New York native John Wood for $60. John Wood later founded Quincy, which at the time was coined Bluffs, Illinois.


title: Quincy, Illinois

text: In 1825, Bluffs renamed their community Quincy and became the seat of government for Adams County, both named after newly elected President John Quincy Adams. In addition, they originally named the town square John Square until eventually changing it to Washington Square. In June 1834, Quincy was incorporated, with Archibald Williams, Joseph T. Holmes, S. W. Rogers, Levi Wells, and Michael Mast elected as trustees. Quincy incorporated as a city in 1840, with Ebenezer Moore elected as its first mayor.


title: Quincy, Illinois

text: In 1837, following the signing of Missouri Executive Order 44, which is an extermination order, many members of the Church of Jesus Christ of Latter-day Saints fled persecution in Missouri and found shelter in Quincy. Despite being vastly outnumbered by Mormon refugees, residents provided food and lodging for the displaced people. Joseph Smith then led members of the Church of Jesus Christ of Latter-day Saints upstream to Nauvoo, Illinois, in hopes of finding a permanent home. Also in 1838, Quincy sheltered the Pottawatomie tribe as they were forcibly relocated from Indiana to Kansas.


title: Quincy, Illinois

text: The 1850s and 1860s brought increased prosperity to Quincy. Steamboats and railroads began linking Quincy to places west, making the city a frequent destination for immigrants. The founding of the Chicago, Burlington and Quincy Railroad in 1855, and the construction of the Quincy Rail Bridge, were major drivers for creating a transportation hub in the region to further commerce. It is during this time that the city's population grew enormously, from just under 7,000 residents in 1850 to 24,000 by 1870, helping Quincy surpass Peoria in becoming the second-largest city in the state (at that time).


title: Quincy, Illinois

text: One famous former resident of Quincy is George E. Pickett. The future Confederate general as a young man came to Quincy to live, and learn the law, from his uncle Alexander Johnson in the 1840s. Johnson was acquainted with Abraham Lincoln, and Pickett and Lincoln may have even met each other in Quincy.


title: Quincy, Illinois

text: In 1860, Quincy founder and Lieutenant Governor John Wood inherited the governorship after William H. Bissell died while in office. At the time, he was overseeing business interests and the construction of his mansion. The Illinois legislature allowed him to stay in Quincy during his tenure, effectively making Quincy a "second" capitol for the state. His absence from the official governor's office in Springfield provided Abraham Lincoln a space for planning his presidential run.


title: Quincy, Illinois

text: The matter of slavery was a major religious and social issue in Quincy's early years. The Illinois city's location, separated only by the Mississippi River from the slave state of Missouri, which was a hotbed of political controversy on the issue, made Quincy itself a hotbed of political controversy on slavery. Richard Eells, who was a staunch abolitionist, built his home in Quincy in 1835 and sheltered runaway slaves on their way to Chicago. His home became a major stop on the Underground Railroad. The divide over slavery climaxed in 1858, when Quincy hosted the sixth Senatorial debate by U.S. Senator Stephen A. Douglas and his challenger, Abraham Lincoln. With a crowd of 12,000 in attendance, Quincy was the largest community at which Lincoln and Douglas debated.


title: Quincy, Illinois

text: Lincoln and Douglas again confronted each other in the 1860 Presidential election and the resulting campaign again divided Quincy and the surrounding region. Lincoln enthusiasts and Quincy's chapter of the Republican Party's para-military organization "Wide Awakes", while en route to a political rally in Plainville, marched upon nearby Payson, which was a community predominantly filled with Douglas supporters. Although a confrontation was avoided while en route to Plainville, Douglas supporters shot upon the Wide Awakes on their journey back to Quincy, resulting in a skirmish known as the Stone Prairie Riots.


title: Quincy, Illinois

text: The Civil War brought increasing prosperity to Quincy. Although the battles took place far from the city, Quincy was the organization site for several Illinois volunteer infantry regiments, including the 16th, 50th, 78th, 84th, 119th, 137th, 138th, and 151st. Following the Reconstruction Era, Quincy was selected as the location for Illinois' first Veteran's Home in 1886.


title: Quincy, Illinois

text: Early immigrants to Quincy came predominately from New England, seeking better land. They brought with them progressive values, such as public education and abolitionism. Starting in the 1840s, migrants from Germany settled in Quincy to escape revolutions among the German provinces and conflicts between the European powers. German migrants mainly lived in close proximity to one another and settled predominantly in the southern parts of the city, influencing much of Quincy's historic architecture and creating the South Side German Historic District. Collectively, the south side of Quincy became known as "Calftown", due to the fact that nearly every household possessed a cow. Among the notable German-Americans from Quincy's Southside was Louise Maertz (1837–1918), a nurse during the American Civil War.


title: Quincy, Illinois

text: In 1860, a group of Franciscan friars founded the St. Francis Solanus College, which later developed into Quincy University.


title: Quincy, Illinois

text: Throughout the 19th century, Quincy had grown from a backwater hamlet along the Mississippi River to become one of the state's most important cities and ports. Activity from rail and steamboat continued to flourish and Quincy benefited from the increased traffic. It was during the early decades of the 20th century that many of the city's historic buildings in the Downtown Quincy Historic District were constructed, including the city's first skyscraper, the Western Catholic Union Building, in 1925.


title: Quincy, Illinois

text: The increasing presence of the automobile led Quincy to consider alternatives to Mississippi River crossings. Prior to the automobile, the most common means of crossing the near-mile wide river was by boat or ferry. In 1928, construction began on the Memorial Bridge which was a two-lane truss toll bridge; it opened in May 1930. By 1945, the city had repaid its outstanding bonds and eliminated the toll.


title: Quincy, Illinois

text: On April 12, 1945, a tornado ripped through the business district of Quincy and severely damaged the courthouse. The wind was so severe that it blew the roof off the structure, damaging it beyond repair. Because the incident occurred a few hours after news reached Quincy of President Roosevelt's death, several residents joked that "FDR and God were just fighting over the power-up there." Five years passed before a new courthouse was completed.


title: Quincy, Illinois

text: In 1987, the cable-stayed Bayview Bridge was constructed with the intent of alleviating traffic on the aging Memorial Bridge. Today, both bridges complement each other by carrying westbound (Bayview) and eastbound (Memorial) traffic. Although the lighting was originally intended for the Bayview Bridge during its construction phase, the actual installation of lights didn't occur until 2015.


title: Quincy, Illinois

text: During the Mississippi River flood of 1993, riverside businesses and industries suffered extensive damage when the river crested at a record 32.2 feet (9.81 m), above flood stage. For a time, the Bayview Bridge, one of Quincy's two bridges, was the only bridge open across the Mississippi River between Alton, Illinois and Burlington, Iowa. The Memorial Bridge was closed from the end of June, due to water over its western approach. On July 16, 1993, the Bayview Bridge closed when the river submerged the land on the west side of the Mississippi River at Taylor, Missouri; Quincy's bridges reopened 73 days later on September 26, 1993.


title: Quincy, Illinois

text: On November 19, 1996, the United Express Flight 5925 collided on landing at Quincy with another Beechcraft, a private King Air, that was taking off from an intersecting runway. All occupants of both planes, twelve on board the 5925 and two on board the King Air, were killed as a result.


title: Quincy, Illinois

text: A flood in June 2008 submerged much of Quincy's riverfront and low-lying regions not protected by the bluffs. Record Mississippi River levels occurred on June 22, 2008. The Red Cross accepted donations for Quincy and other communities in Adams County, as natural disaster funds were depleted in 2010.


title: Quincy, Illinois

text: Quincy has been twice recognized as an All-America City and is a participant in the Tree City USA program. In the fall of 2010, Forbes Magazine listed Quincy as the eighth "Best Small City To Raise A Family."


title: Quincy, Illinois

text: As of the 2020 census there were 39,463 people, 17,226 households, and 9,940 families residing in the city. The population density was . There were 19,028 housing units at an average density of . The racial makeup of the city was 86.3% White, 5.87% African American, 0.18% Native American, 1.01% Asian, 0.08% Pacific Islander, 0.95% from other races, and 5.59% from two or more races. Hispanic or Latino of any race were 2.33% of the population.


title: Quincy, Illinois

text: There were 17,226 households, out of which 43.31% had children under the age of 18 living with them, 42.52% were married couples living together, 11.26% had a female householder with no husband present, and 42.30% were non-families. 36.06% of all households were made up of individuals, and 18.12% had someone living alone who was 65 years of age or older. The average household size was 2.97 and the average family size was 2.26.


title: Quincy, Illinois

text: The city's age distribution consisted of 21.4% under the age of 18, 8.7% from 18 to 24, 24.9% from 25 to 44, 24.3% from 45 to 64, and 20.7% who were 65 years of age or older. The median age was 40.3 years. For every 100 females, there were 92.1 males. For every 100 females age 18 and over, there were 91.4 males.


title: Quincy, Illinois

text: The median income for a household in the city was $46,935, and the median income for a family was $64,891. Males had a median income of $40,636 versus $26,977 for females. The per capita income for the city was $29,105. About 11.4% of families and 15.3% of the population were below the poverty line, including 22.7% of those under age 18 and 12.7% of those age 65 or over.


title: Quincy, Illinois

text: Quincy is located at (39.932335, -91.388737). It is adjacent to the Mississippi River and Quincy Bay, a large inlet of water fed by Cedar and Homan Creeks. According to the 2021 census gazetteer files, Quincy has a total area of , of which (or 99.73%) is land and (or 0.27%) is water.


title: Quincy, Illinois

text: The city is situated on bluffs overlooking the Mississippi River. Adjacent to Quincy, on the Missouri side of the river, is West Quincy, Missouri and a vast floodplain used primarily for farming. East of Quincy lies the Quincy Hills geographic region, a region of hills that are similar to the Lincoln Hills in Missouri, where a mixture of rolling hills, woods, and farming shape the landscape. Flat prairie lie north of Quincy and, as the Mississippi turns sharply to the southwest; bluffs, floodplain, and farmland lie to the south and southwest of the city.


title: Quincy, Illinois

text: The Quincy micropolitan area includes Adams County, Illinois and Lewis County, Missouri and together hold a population of 75,546. Due to its proximity to Hannibal, Missouri, the two communities have been bulked into Quincy-Hannibal, IL-MO Combined Statistical Area which holds approximately 116,000 residents. As of the 2010 Census, it is currently ranked as the 156th most populated CSA in the United States.


title: Quincy, Illinois

text: Geographically, Quincy is the largest city and central hub of the Tri-State region, encompassing western Illinois, northeastern Missouri, and southeastern Iowa.


title: Quincy, Illinois

text: Quincy has several suburbs. North Quincy is the city's most populated suburb and lies to the north, beyond a rail line and a large creek. Hickory Grove, Illinois is an edge town and lies adjacent to Quincy to its east, bordered by Interstate 172. The town of Marblehead lies to the south, and West Quincy to the west.


title: Quincy, Illinois

text: The Hannibal–Quincy micropolitan area is also technically not located within the nearby St. Louis metropolitan, but are regionally associated due to their proximity and accessibility to Greater St. Louis.


title: Quincy, Illinois

text: Companies based in Quincy include Niemann Foods, Gardner Denver and The Knapheide Manufacturing Company. GatesAir Television and Radio Transmission has a facility in town, as does Broadcast Electronics. Titan Wheel (Titan International) is also located in Quincy. Blessing Hospital, the Quincy Public Schools and Titan are the top three employers in the area.


title: Quincy, Illinois

text: In 1978, Quincy formed the Great River Economic Development Foundation, a private, non-profit organization designed to retain existing businesses and attract new ones to the area. This organization has been instrumental in putting the Quincy-Hannibal Area on the map as a distinct region in conjunction with the major metropolitan areas nearby such as Chicago, IL, St. Louis, MO, and even Kansas City, MO. As a whole, Quincy falls from average to just above average in several economic categories in comparison to the national averages.


title: Quincy, Illinois

text: The cost of living in Quincy is well below the national average. The city is also below the national averages in cost of food, utilities and other miscellaneous costs. In the fall of 2010 Quincy was listed as eighth in the top fifteen small cities to raise a family in the United States by Forbes magazine for its commute times, high school graduation rate, median household income, home ownership rate and cost of living. Forbes compared 126 cities with a population under 100,000 and ranked them on these five quality-of-life measures.


title: Quincy, Illinois

text: Quincy's television market includes the cities of Quincy, Hannibal, Macomb, and Keokuk. The market was widely served by Insight Communications through 2007. In January 2008, Comcast took control of the cable television system. Satellite television services are provided by DirecTV or Dish.


title: Quincy, Illinois

text: The city is usually combined with Hannibal due to its proximity and labeled as the 170th market on the DMA chart. With regards to television service, Quincy and the surrounding region are served by affiliates of ABC, CBS, NBC, Fox, and the CW networks. STARadio Corporation and Quincy Media own many of the local media outlets in the region. As of February 2006, Quincy can receive 17 FM stations, 5 AM stations, and one NOAA Wideband Weather Radio station.


title: Quincy, Illinois

text: Quincy and the surrounding region lie in a blended zone of midwestern culture, where influences from the Heartland and Rust Belt converge. It is also a community that deeply admires the arts, as it is home to America's first Arts Council, Quincy Society of Fine Arts, which was founded in 1947 by George M. Irwin. Irwin also founded Quincy Little Symphony (now known as the Quincy Symphony Orchestra Association) in 1947. Numerous nonprofit arts organizations provide the community with opportunities for entertainment, workshops, hands-on creative experiences, annual festivals, gallery and museum exhibit openings, theatre, architecture, education and much more. Quincy was also named to Expedia's list of America's Most Artistic Towns in 2017 and 2018.


title: Quincy, Illinois

text: Like most Mississippi river cities, blues music has made a lasting impression upon the city and every year the free admission "Blues in the District" concert series brings the music to Washington Park, where artists are invited to sing and play for spectators the second and fourth Friday of June, July, and August. Free music events are also offered by the Quincy Park Band throughout the summer and Quincy Concert Band twice a year.


title: Quincy, Illinois

text: The Dogwood Parade and festival is an annual event held in early-May celebrating the blossoming Dogwoods located throughout the city. Washington Park hosts amusement rides and a parade marches down Maine Street. Washington Park and downtown also become the focal point of activity for farmer's markets, Q-Fest, formerly the Midsummer Arts Faire, the Tin Dusters, and the Gus Macker 3-on-3 Basketball tournament.


title: Quincy, Illinois

text: The Historical Society of Quincy and Adams County engage the community in various events at the History Museum, the John Wood Mansion and Woodland Cemetery. In 2018, Quincy Community Theatre opened its 81st season. Quincy Art Center and Quincy Museum host the annual Art Fest & Folk Life Festival on Maine Street each September and provide various educational opportunities.


title: Quincy, Illinois

text: Quincy's riverfront is also a center for popular activities throughout the year, including the Fourth of July display on the Quincy Bay, outdoor showings of movies, and concerts. The Quincy Area Convention and Visitors Bureau is housed in a unique example of Mediterranean Revival architecture, the Villa Kathrine, along the river bluff and provides visitors and those traveling along the Great River Road a stop with informational materials about Quincy and the surrounding area.


title: Quincy, Illinois

text: The Historic Downtown District is the premier destination for dining, entertainment and shopping. With the backdrop of historic architecture, The District merges the past with a touch of modern flair to bring customers all the modern conveniences they would want. Broadway Street leads from the Mississippi River through the east end of the town. Along the route are numerous chain franchises, stores, Quincy Mall and various strip malls for additional shopping opportunities. The Quincy Area Chamber of Commerce was established in 1887 to promote and enhance the business climate and economic well-being of the Quincy area.


title: Quincy, Illinois

text: The Quincy YMCA and The Salvation Army Kroc Center provide fitness and recreational activities. There also several dance and yoga studios available. The Quincy Park District also offers public access to numerous parks, trails, facilities and programs throughout the city.


title: Quincy, Illinois

text: Quincy is home to a diverse and vibrant collection of buildings that have come to be a tourist attraction in and of themselves. South of downtown is the South Side German Historic District, which holds many of the German-influenced structures that early immigrants built. A central site in the district is the "Dick Brothers Brewery" Buildings, which were constructed in 1857 and rivaled many larger breweries. The lager tunnel system and natural aquifer can still be found underground. Although the brewery survived Prohibition by bottling water and other beverages, slow modernization efforts forced the brewery into bankruptcy. However, the buildings remain and are being renovated for public use and commercial space. Other examples of rich German-influence in Quincy can also be seen in the many brick homes within the district.


title: Quincy, Illinois

text: Other than the South Side, Maine Street and the East End are popular strips where Quincy's rich architectural history is displayed. Once housing some of Quincy's elite, many of the homes in these regions are influenced mainly by Victorian schools. Known residents of this part of town included Richard Newcomb and city founder John Wood. Today, the Newcomb residence functions as the "Quincy Museum" and was once featured on the cover of National Geographic as "one of the most architecturally significant corners in the United States." There are many organizations in the town that continue to oversee renovations to structures, such as the Historical Society of Quincy & Adams County, and some residents allow for tours of their 19th Century homes.


title: Quincy, Illinois

text: There is also a significant Mediterranean influence to Quincy with the Villa Kathrine and B'nai Sholom Temple. In 1900, Quincy resident W. George Metz commissioned George Behrensmeyer to design a Moroccan-style home overlooking the river. It included a harem, courtyard, and reflecting pool. Today, the Villa Kathrine functions as the visitor's center. The Temple B'nai Sholom is another structure that was heavily influenced by the Moorish revival in the United States.


title: Quincy, Illinois

text: Quincy has a number of educational institutions within the city or close by. One of the largest Illinois high schools outside of the Chicago area, Quincy Senior High School is located on Maine Street in Quincy. Quincy Notre Dame High School, a private Catholic high school, is also located in Quincy. Quincy University is Quincy's most highly decorated school, and was established in the 1860s. On the city's east side, John Wood Community College is the regional community college. Gem City College is located in the heart of downtown Quincy and the Blessing-Rieman College of Nursing is located next door to Blessing Hospital. Regionally, Quincy is within driving distance of Western Illinois University in Macomb, Hannibal-LaGrange College downriver in Hannibal, Missouri, and Culver-Stockton College in Canton, Missouri.


title: Quincy, Illinois

text: The Quincy Park District was founded in 1940 when five commissioners were elected to govern the district. Today the board for the Park District is made up of seven volunteers who serve four-year terms. Quincy Park District is made up of which is divided into 26 parks. The 26 parks located in Quincy are All-American Park, Berrian Park, Bob Bangert Park, Bob Mays Park, Boots Bush Park, Clat Adams Bicentennial Park, Edgewater Park, Emerson Park, Gardner Park, Indian Mounds Park, Johnson Park, Kesler Park, Leon Bailey Park, Lincoln Park, Madison Park, Moorman Park, Parker Heights Park, Quinsippi Island, Reservoir Park, Riverview Park, South Park, Sunset Park, Washington Park, Wavering Park, and Westview Park. Washington Park was the first park in Quincy, IL. It is located downtown and sits on . Washington Park served as one of the locations in Illinois for the Lincoln-Douglas debates. Quinsippi Island is accessible through the All-American Park and comprises . Bob Mays Park sits on fifty acres of land and opened in 2008. The site of the first public pool was at Indian Mounds Park. It also sits on of land. Moorman Park where visitors can find baseball and softball diamonds. Moorman Park sits on and includes a batting cage and mini-golf course. Besides a swimming pool and baseball/softball diamonds, there are also tennis courts for the community to use. One park that has tennis courts is Reservoir Park where many city tennis tournaments are held. This is just some of the information regarding the parks in Quincy.


title: Quincy, Illinois

text: Quincy is home to Blessing Hospital and Quincy Medical Group. Specialty areas include a cancer center, cardiovascular center, outpatient surgery center, Level 2 trauma center, and rehabilitation. Blessing also operates the Blessing Rieman College of Nursing.


title: Quincy, Illinois

text: Interstate 72 passes approximately south of Quincy. Its spur route, Interstate 172, passes just east of town. In recent years, the Prairie Trails Shopping Complex has been a focal point for development in this area. Illinois Route 104 (Broadway) is a main east–west artery from the Mississippi River bridges to Interstate 172. Illinois Route 96 enters the city from the southeast and travels north (through the east side of Quincy) to U.S. Route 24. Illinois Route 57 branches south from U.S. 24 downtown and passes Quincy's Civic Center on its way to Interstate 172 southeast of the city. Illinois 96 also serves as the Great River Road, which follows the path of the Mississippi River. Eastbound U.S. 24 crosses the Mississippi River from Missouri on the Quincy Memorial Bridge, while westbound traffic uses the newer Bayview Bridge. Bayview bridge was constructed in 1986, but was not built as a four-lane bridge because of budget cuts, as the cable suspension made it unaffordable to build a four-lane bridge. Other groups claimed that business in the downtown part of Quincy would decline if the Memorial bridge was shut down.


title: Quincy, Illinois

text: On the Missouri side, U.S. 61 carries the Avenue of the Saints, a four-lane highway connecting Saint Louis to Minneapolis–Saint Paul. The Avenue of the Saints derives its name from Saint Louis and Saint Paul, Minnesota.


title: Quincy, Illinois

text: Cape Air operates daily flights to Chicago-O'Hare, which is 222 flying miles from Quincy and St. Louis-Lambert, which is 93 miles away. It is the 425th busiest airport in America based on passenger counts. Flight instruction, plane rentals and hangar space are also available at the airport. Longest Runway: 7,098 ft. Width: 150 ft.


title: Quincy, Illinois

text: Quincy is an Amtrak community with a railroad station on the north side of town. Two state-supported trains, the "Illinois Zephyr" and the "Carl Sandburg" link Quincy with Chicago, Amtrak's main hub, with connections to hundreds of cities across the country. The "Illinois Zephyr" departs in the morning and arrives in the evening, while the "Carl Sandburg" arrives mid-day and departs in the late afternoon. Both make the same stops to Chicago's Union Station.


title: Quincy, Illinois

text: Burlington Northern Santa Fe and Norfolk Southern offer multiple freight trains daily and Burlington Junction Rail Road offers short line service many sites and development districts.


title: Quincy, Illinois

text: Quincy is home to the northernmost port on the Mississippi River for 12-month barge traffic. The municipal barge dock currently serves multiple industries in the South Quincy Development District. The Mid America Intermodal Port Commission is working to secure funding for an additional multimillion-dollar intermodal port facility.


title: Quincy, Illinois

text: Quincy Transit Lines provides fixed-route and paratransit bus service throughout Quincy. There are four fixed routes, and each route is split into two branches. Those routes run Monday–Saturday, between 6:00 am and 6:00 pm. During Sundays and holidays, Quincy Transit Lines operates a pared-down version of the fixed-route system that is made up of two routes – the North route and the South route.


title: Quincy, Illinois

text: Quincy Transit Lines route Route 4 stops near the city's Amtrak station at Wissman Lane/30th Street intersection.


title: Blowout preventer

text: A blowout preventer (BOP) (pronounced B-O-P, not "bop") is a specialized valve or similar mechanical device, used to seal, control and monitor oil and gas wells to prevent blowouts, the uncontrolled release of crude oil or natural gas from a well. They are usually installed in stacks of other valves.


title: Blowout preventer

text: Blowout preventers were developed to cope with extreme erratic pressures and uncontrolled flow (formation kick) emanating from a well reservoir during drilling. Kicks can lead to a potentially catastrophic event known as a blowout. In addition to controlling the downhole (occurring in the drilled hole) pressure and the flow of oil and gas, blowout preventers are intended to prevent tubing (e.g. drill pipe and well casing), tools and drilling fluid from being blown out of the wellbore (also known as bore hole, the hole leading to the reservoir) when a blowout threatens. Blowout preventers are critical to the safety of crew, rig (the equipment system used to drill a wellbore) and environment, and to the monitoring and maintenance of well integrity; thus blowout preventers are intended to provide fail-safety to the systems that include them.


title: Blowout preventer

text: The term "BOP" is used in oilfield vernacular to refer to blowout preventers. The abbreviated term "preventer", usually prefaced by a type (e.g. ram preventer), is used to refer to a single blowout preventer unit. A blowout preventer may also simply be referred to by its type (e.g. ram). The terms "blowout preventer", "blowout preventer stack" and "blowout preventer system" are commonly used interchangeably and in a general manner to describe an assembly of several stacked blowout preventers of varying type and function, as well as auxiliary components. A typical subsea deepwater blowout preventer system includes components such as electrical and hydraulic lines, control pods, hydraulic accumulators, test valve, kill and choke lines and valves, riser joint, hydraulic connectors, and a support frame.


title: Blowout preventer

text: Two categories of blowout preventer are most prevalent: "ram" and "annular". BOP stacks frequently utilize both types, typically with at least one annular BOP stacked above several ram BOPs. Blowout preventers are used on land wells, offshore rigs, and subsea wells. Land and subsea BOPs are secured to the top of the wellbore, known as the wellhead. BOPs on offshore rigs are mounted below the rig deck. Subsea BOPs are connected to the offshore rig above by a drilling riser that provides a continuous pathway for the drill string and fluids emanating from the wellbore. In effect, a riser extends the wellbore to the rig. Blowout preventers do not always function correctly. An example of this is the "Deepwater Horizon" blowout, where the pipe line going through the BOP was slightly bent and the BOP failed to cut the pipe.


title: Blowout preventer

text: Blowout preventers come in a variety of styles, sizes and pressure ratings. Several individual units serving various functions are combined to compose a blowout preventer stack. Multiple blowout preventers of the same type are frequently provided for redundancy, an important factor in the effectiveness of fail-safe devices.


title: Blowout preventer

text: In drilling a typical high-pressure well, drill strings are routed through a blowout preventer stack toward the reservoir of oil and gas. As the well is drilled, drilling fluid, "mud", is fed through the drill string down to the drill bit, "blade", and returns up the wellbore in the ring-shaped void, annulus, between the outside of the drill pipe and the casing (piping that lines the wellbore). The column of drilling mud exerts downward hydrostatic pressure to counter opposing pressure from the formation being drilled, allowing drilling to proceed.


title: Blowout preventer

text: When a kick (influx of formation fluid) occurs, rig operators or automatic systems close the blowout preventer units, sealing the annulus to stop the flow of fluids out of the wellbore. Denser mud is then circulated into the wellbore down the drill string, up the annulus and out through the choke line at the base of the BOP stack through chokes (flow restrictors) until downhole pressure is overcome. Once “kill weight” mud extends from the bottom of the well to the top, the well has been “killed”. If the integrity of the well is intact drilling may be resumed. Alternatively, if circulation is not feasible it may be possible to kill the well by "bullheading", forcibly pumping in the heavier mud from the top through the kill line connection at the base of the stack. This is less desirable because of the higher surface pressures likely needed and the fact that much of the mud originally in the annulus must be forced into receptive formations in the open hole section beneath the deepest casing shoe.


title: Blowout preventer

text: If the blowout preventers and mud do not restrict the upward pressures of a kick, a blowout results, potentially shooting tubing, oil and gas up the wellbore, damaging the rig, and leaving well integrity in question.


title: Blowout preventer

text: Since BOPs are important for the safety of the crew and natural environment, as well as the drilling rig and the wellbore itself, authorities recommend, and regulations require, that BOPs be regularly inspected, tested and refurbished. Tests vary from daily test of functions on critical wells to monthly or less frequent testing on wells with low likelihood of control problems.


title: Blowout preventer

text: Exploitable reservoirs of oil and gas are increasingly rare and remote, leading to increased subsea deepwater well exploration and requiring BOPs to remain submerged for as long as a year in extreme conditions. As a result, BOP assemblies have grown larger and heavier (e.g. a single ram-type BOP unit can weigh in excess of 30,000 pounds), while the space allotted for BOP stacks on existing offshore rigs has not grown commensurately. Thus a key focus in the technological development of BOPs over the last two decades has been limiting their footprint and weight while simultaneously increasing safe operating capacity.


title: Blowout preventer

text: BOPs come in two basic types, "ram" and "annular". Both are often used together in drilling rig BOP stacks, typically with at least one annular BOP capping a stack of several ram BOPs.


title: Blowout preventer

text: The ram BOP was invented by James Smither Abercrombie and Harry S. Cameron in 1922, and was brought to market in 1924 by Cameron Iron Works.


title: Blowout preventer

text: A ram-type BOP is similar in operation to a gate valve, but uses a pair of opposing steel plungers, rams. The rams extend toward the center of the wellbore to restrict flow or retract open in order to permit flow. The inner and top faces of the rams are fitted with packers (elastomeric seals) that press against each other, against the wellbore, and around tubing running through the wellbore. Outlets at the sides of the BOP housing (body) are used for connection to choke and kill lines or valves.


title: Blowout preventer

text: Pipe rams close around a drill pipe, restricting flow in the annulus (ring-shaped space between concentric objects) between the outside of the drill pipe and the wellbore, but do not obstruct flow within the drill pipe. Variable-bore pipe rams can accommodate tubing in a wider range of outside diameters than standard pipe rams, but typically with some loss of pressure capacity and longevity. A pipe ram should not be closed if there is no pipe in the hole.


title: Blowout preventer

text: Blind rams (also known as sealing rams), which have no openings for tubing, can close off the well when the well does not contain a drill string or other tubing, and seal it.


title: Blowout preventer

text: Shear rams are designed to shear the pipe in the well and seal the wellbore simultaneously. It has steel blades to shear the pipe and seals to seal the annulus after shearing the pipe.


title: Blowout preventer

text: Blind shear rams (also known as shear seal rams, or sealing shear rams) are intended to seal a wellbore, even when the bore is occupied by a drill string, by cutting through the drill string as the rams close off the well. The upper portion of the severed drill string is freed from the ram, while the lower portion may be crimped and the “fish tail” captured to hang the drill string off the BOP.


title: Blowout preventer

text: In addition to the standard ram functions, variable-bore pipe rams are frequently used as test rams in a modified blowout preventer device known as a stack test valve. Stack test valves are positioned at the bottom of a BOP stack and resist downward pressure (unlike BOPs, which resist upward pressures). By closing the test ram and a BOP ram around the drill string and pressurizing the annulus, the BOP is pressure-tested for proper function.


title: Blowout preventer

text: The original ram BOPs of the 1920s were simple and rugged manual devices with minimal parts. The BOP housing (body) had a vertical well bore and horizontal ram cavity (ram guide chamber). Opposing rams (plungers) in the ram cavity translated horizontally, actuated by threaded ram shafts (piston rods) in the manner of a screw jack. Torque from turning the ram shafts by wrench or hand wheel was converted to linear motion and the rams, coupled to the inner ends of the ram shafts, opened and closed the well bore. Such screw jack type operation provided enough mechanical advantage for rams to overcome downhole pressures and seal the wellbore annulus.


title: Blowout preventer

text: Hydraulic rams BOPs were in use by the 1940s. Hydraulically actuated blowout preventers had many potential advantages. The pressure could be equalized in the opposing hydraulic cylinders causing the rams to operate in unison. Relatively rapid actuation and remote control were facilitated, and hydraulic rams were well-suited to high pressure wells.


title: Blowout preventer

text: Because BOPs are depended on for safety and reliability, efforts to minimize the complexity of the devices are still employed to ensure longevity. As a result, despite the ever-increasing demands placed on them, state of the art ram BOPs are conceptually the same as the first effective models, and resemble those units in many ways.


title: Blowout preventer

text: Ram BOPs for use in deepwater applications universally employ hydraulic actuation. Threaded shafts are often still incorporated into hydraulic ram BOPs as lock rods that hold the ram in position after hydraulic actuation. By using a mechanical ram locking mechanism, constant hydraulic pressure need not be maintained. Lock rods may be coupled to ram shafts or not, depending on manufacturer. Other types of ram locks, such as wedge locks, are also used.


title: Blowout preventer

text: Typical ram actuator assemblies (operator systems) are secured to the BOP housing by removable bonnets. Unbolting the bonnets from the housing allows BOP maintenance and facilitates the substitution of rams. In that way, for example, a pipe ram BOP can be converted to a blind shear ram BOP.


title: Blowout preventer

text: Shear-type ram BOPs require the greatest closing force in order to cut through tubing occupying the wellbore. Boosters (auxiliary hydraulic actuators) are frequently mounted to the outer ends of a BOP's hydraulic actuators to provide additional shearing force for shear rams. If a situation arises whereby the shear rams are to be activated, it is best practice for the Driller to have the string spaced as to ensure the rams will shear the body of the drillpipe as opposed to having a tooljoint (much thicker metal) across the shear rams.


title: Blowout preventer

text: Ram BOPs are typically designed so that well pressure will help maintain the rams in their closed, sealing position. That is achieved by allowing fluid to pass through a channel in the ram and exert pressure at the ram's rear and toward the center of the wellbore. Providing a channel in the ram also limits the thrust required to overcome well bore pressure.


title: Blowout preventer

text: Single ram and double ram BOPs are commonly available. The names refer to the quantity of ram cavities (equivalent to the effective quantity of valves) contained in the unit. A double ram BOP is more compact and lighter than a stack of two single ram BOPs while providing the same functionality, and is thus desirable in many applications. Triple ram BOPs are also manufactured, but not as common.


title: Blowout preventer

text: Technological development of ram BOPs has been directed towards deeper and higher pressure wells, greater reliability, reduced maintenance, facilitated replacement of components, facilitated ROV intervention, reduced hydraulic fluid consumption, and improved connectors, packers, seals, locks and rams. In addition, limiting BOP weight and footprint are significant concerns to account for the limitations of existing rigs.


title: Blowout preventer

text: The highest-capacity large-bore ram blowout preventer on the market, as of July 2010, Cameron's EVO 20K BOP, has a hold-pressure rating of 20,000 psi, ram force in excess of 1,000,000 pounds, and a well bore diameter of 18.75 inches.


title: Blowout preventer

text: The annular blowout preventer was invented by Granville Sloan Knox in 1946; a U.S. patent for it was awarded in 1952. Often around the rig it is called the "Hydril", after the name of the original manufacturer of such devices.


title: Blowout preventer

text: An annular-type blowout preventer can close around the drill string, casing or a non-cylindrical object, such as the kelly. Drill pipe including the larger-diameter tool joints (threaded connectors) can be "stripped" (i.e., moved vertically while pressure is contained below) through an annular preventer by careful control of the hydraulic closing pressure. Annular blowout preventers are also effective at maintaining a seal around the drillpipe even as it rotates during drilling. Regulations typically require that an annular preventer be able to completely close a wellbore, but annular preventers are generally not as effective as ram preventers in maintaining a seal on an open hole. Annular BOPs are typically located at the top of a BOP stack, with one or two annular preventers positioned above a series of several ram preventers.


title: Blowout preventer

text: An annular blowout preventer uses the principle of a wedge to shut in the wellbore. It has a donut-like rubber seal, known as an elastomeric packing unit, reinforced with steel ribs. The packing unit is situated in the BOP housing between the head and hydraulic piston. When the piston is actuated, its upward thrust forces the packing unit to constrict, like a sphincter, sealing the annulus or openhole. Annular preventers have only two moving parts, piston and packing unit, making them simple and easy to maintain relative to ram preventers.


title: Blowout preventer

text: The original type of annular blowout preventer uses a “wedge-faced” (conical-faced) piston. As the piston rises, vertical movement of the packing unit is restricted by the head and the sloped face of the piston squeezes the packing unit inward, toward the center of the wellbore.


title: Blowout preventer

text: In 1972, Ado N. Vujasinovic was awarded a patent for a variation on the annular preventer known as a spherical blowout preventer, so-named because of its spherical-faced head. As the piston rises the packing unit is thrust upward against the curved head, which constricts the packing unit inward. Both types of annular preventer are in common use.


title: Blowout preventer

text: When wells are drilled on land or in very shallow water where the wellhead is above the water line, BOPs are activated by hydraulic pressure from a remote accumulator. Several control stations will be mounted around the rig. They also can be closed manually by turning large wheel-like handles.


title: Blowout preventer

text: In deeper offshore operations with the wellhead just above the mudline on the sea floor, there are five primary ways by which a BOP can be controlled. The possible means are:


title: Blowout preventer

text: Two control pods are provided on the BOP for redundancy. Electrical signal control of the pods is primary. Acoustical, ROV intervention and dead-man controls are secondary.


title: Blowout preventer

text: An emergency disconnect system/sequence, or EDS, disconnects the rig from the well in case of an emergency. The EDS is also intended to automatically trigger the deadman switch, which closes the BOP, kill and choke valves. The EDS may be a subsystem of the BOP stack's control pods or separate.


title: Blowout preventer

text: Pumps on the rig normally deliver pressure to the blowout preventer stack through hydraulic lines. Hydraulic accumulators are on the BOP stack enable closure of blowout preventers even if the BOP stack is disconnected from the rig. It is also possible to trigger the closing of BOPs automatically based on too high pressure or excessive flow.


title: Blowout preventer

text: Individual wells along the U.S. coastline may also be required to have BOPs with backup acoustic control. General requirements of other nations, including Brazil, were drawn to require this method. BOPs featuring this method may cost as much as US$500,000 more than those that omit the feature.


title: Blowout preventer

text: During the "Deepwater Horizon" drilling rig explosion incident on April 20, 2010, the blowout preventer should have been activated automatically, cutting the drillstring and sealing the well to preclude a blowout and subsequent oil spill in the Gulf of Mexico, but it failed to fully engage. Underwater robots (ROVs) later were used to manually trigger the blind shear ram preventer, to no avail.


title: Blowout preventer

text: As of May 2010 it was unknown why the blowout preventer failed. Chief surveyor John David Forsyth of the American Bureau of Shipping testified in hearings before the Joint Investigation of the Minerals Management Service and the U.S. Coast Guard investigating the causes of the explosion that his agency last inspected the rig's blowout preventer in 2005. BP representatives suggested that the preventer could have suffered a hydraulic leak. Gamma-ray imaging of the preventer conducted on May 12 and May 13, 2010 showed that the preventer's internal valves were partially closed and were restricting the flow of oil. Whether the valves closed automatically during the explosion or were shut manually by remotely operated vehicle work is unknown. A statement released by Congressman Bart Stupak revealed that, among other issues, the emergency disconnect system (EDS) did not function as intended and may have malfunctioned due to the explosion on the Deepwater Horizon.


title: Blowout preventer

text: The permit for the Macondo Prospect by the Minerals Management Service in 2009 did not require redundant acoustic control means. Insofar as the BOPs could not be closed successfully by underwater manipulation (ROV Intervention), pending results of a complete investigation, it is uncertain whether this omission was a factor in the blowout.


title: Blowout preventer

text: Documents discussed during congressional hearings June 17, 2010, suggested that a battery in the device's control pod was flat and that the rig's owner, Transocean, may have "modified" Cameron's equipment for the Macondo site (including incorrectly routing hydraulic pressure to a stack test valve instead of a pipe ram BOP) which increased the risk of BOP failure, in spite of warnings from their contractor to that effect. Another hypothesis was that a junction in the drilling pipe may have been positioned in the BOP stack in such a way that its shear rams had an insurmountable thickness of material to cut through.


title: Blowout preventer

text: It was later discovered that a second piece of tubing got into the BOP stack at some point during the Macondo incident, potentially explaining the failure of the BOP shearing mechanism. As of July 2010 it was unknown whether the tubing might have been casing that shot up through the well or perhaps broken drill pipe that dropped into the well. The DNV final report indicated that the second tube was the segment of the drill string that was ejected after being cut by the blow out preventer shears.


title: Blowout preventer

text: On July 10, 2010 BP began operations to install a sealing cap, also known as a capping stack, atop the failed blowout preventer stack. Based on BP's video feeds of the operation the sealing cap assembly, called Top Hat 10, included a stack of three blind shear ram BOPs manufactured by Hydril (a GE Oil & Gas company), one of Cameron's chief competitors. By July 15 the 3 ram capping stack had sealed the Macondo well, if only temporarily, for the first time in 87 days.


title: Blowout preventer

text: The U.S. government wanted the failed blowout preventer to be replaced in case of any pressure change that occurs when the relief well intersected with the well. On September 3, 2010, at 1:20 p.m. CDT the 300 ton failed blowout preventer was removed from the well and began being slowly lifted to the surface. Later that day a replacement blowout preventer was placed on the well. On September 4 at 6:54 p.m. CDT the failed blowout preventer reached the surface of the water and at 9:16 p.m. CDT it was placed in a special container on board the vessel Helix Q4000. The failed blowout preventer was taken to a NASA facility in Louisiana for examination by Det Norske Veritas (DNV).


title: Blowout preventer

text: On 20 March 2011, DNV presented their report to the US Department of Energy. Their primary conclusion was that while the rams succeeded in partly shearing through the drill pipe they failed to seal the bore because the drill pipe had buckled out of the intended line of action of the rams (because the drill string was caught at a tool joint in the upper annular BOP valve), jamming the shears and leaving the drill string shear actuator unable to deliver enough force to complete its stroke and fold the cut pipe over and seal the well. They did not suggest any failure of actuation as would be caused by faulty batteries. The upper section of the blow out preventer failed to separate as designed due to numerous oil leaks compromising hydraulic actuator operation, and this had to be cut free during recovery.


title: Staunton chess set

text: The Staunton chess set is the standard style of chess pieces, recommended for use in competition by FIDE, the international chess governing body.


title: Staunton chess set

text: The journalist Nathaniel Cooke is credited with the design on the patent, and they are named after the leading English chess master Howard Staunton, who endorsed it; the first 500 sets were numbered and hand-signed by Staunton. This style of set was first made available by Jaques of London in 1849, and it quickly became the standard. The set style and its variations have been used around the world since.


title: Staunton chess set

text: During the late 18th century and early 19th century, the increased interest in the game of chess, particularly in international play, brought about a renewed demand for a more universal model for chess pieces. The variety and styles of the conventional form, which began in the 15th century, had expanded tremendously by the beginning of the 19th century. Conventional types popular during the period included the English Barleycorn chess set, the St. George chess set, the French Regence chess set (named after the in Paris), and the central European forms. Most designs then in use had pieces that were difficult to distinguish, cumbersome during play, and easily tipped.


title: Staunton chess set

text: The Staunton chess set was released in 1849 in response to these issues. The pieces were designed to be easy to use and universally recognized by chess players of diverse backgrounds. It was first released by the purveyors of fine games, John Jaques of London, sport and games manufacturers, of Hatton Garden in London. It became known as the Staunton chess set after Howard Staunton (1810–1874), the chess player and writer who was generally considered the strongest player in the world from 1843–1851. Nathaniel Cooke has long been credited with the design.


title: Staunton chess set

text: One theory of the development of the set is that Cooke had used prestigious architectural concepts, familiar to an expanding class of educated and prosperous gentry. London architects, strongly influenced by the culture of Greece and the culture of ancient Rome, were designing prestigious buildings in the neoclassical style. The appearance of the new chessmen was based on this style. and the pieces were symbols of "respectable" Victorian society:


title: Staunton chess set

text: There were also practical innovations: A crown emblem was stamped onto a rook and knight of each side to identify their positioning on to the king's side of the board. This was because, in descriptive chess notation, the rooks and knights were often designated by being the "queen's knight", the "king's rook", etc.


title: Staunton chess set

text: Another possibility is that Jaques, a master turner, had probably been experimenting with a design that not only would be accepted by players but also could be produced at a reasonable cost. In the end, he most likely borrowed and synthesized elements from sets already available to create a new design that used universally recognizable symbols atop conventional stems and bases: The resulting pieces were compact, well balanced, and weighted to provide an understandable, practical playing set.


title: Staunton chess set

text: It may have been a combination of both theories with the synergy of Cooke the entrepreneur and Jaques the artisan.


title: Staunton chess set

text: From 1820 on, diagrams in chess books began to use icons of chess pieces similar in many respects to the Staunton chessmen, including a change from arched crown to coronet for the queen. This shows that the Staunton design may have been taken from these diagrams, very likely created by a printer.


title: Staunton chess set

text: The ebony and boxwood sets were weighted with lead to provide added stability and the underside of each piece was covered with felt, allowing the pieces to slide easily across the board. Some ivory sets were made from African ivory. The king sizes ranged from 3½ to 4½ inches and the sets typically came in a papier-mâché case, each one bearing a facsimile of Staunton's signature under the lid.


title: Staunton chess set

text: The Staunton pieces broadly resemble columns with a wide molded base. Knights feature the sculpted head and neck of a horse. Kings, the tallest pieces, top the column with a stylised crown topped with a cross pattée. Queens are slightly smaller than kings, and feature a coronet topped with a tiny ball (a monde). Rooks feature stylised crenellated battlements and bishops a Western-style mitre. Pawns are the smallest and are topped by a plain ball. Pieces representing human characters (the king, queen, bishop, and pawn) have a flat disk separating the body from the head design, which is known as a collar.


title: Staunton chess set

text: A modified Staunton chess set, described in the FIDE Laws of Chess, is used for the blind and visually impaired. In such a set, the black pieces are differentiated from the white pieces by a small point/spike atop the pieces, and the dark squares are raised above the light squares to allow the user to feel the board and pieces to understand the position. Furthermore, each square has a hole into which pegs on the bottom of each piece are inserted, allowing the user to feel the position of the pieces without moving them or knocking them over.


title: Staunton chess set

text: The design was registered at the Patent Office on 1 March 1849, to Nathaniel Cooke, 198 Strand, London, England as an "Ornamental Design for a set of Chess-Men", under the "Ornamental Designs Act of 1842". At that date, there was no provision for the registration of any design or articles of ivory; registration was limited to Class 2, articles chiefly made of wood.


title: Staunton chess set

text: Cooke was the editor for the "Illustrated London News", where Staunton published chess articles. He convinced the champion to endorse the chess set.


title: Staunton chess set

text: Staunton not only endorsed the product for Jaques of London but promoted it to an extraordinary degree including the lambasting and derision of any other design of chessmen then proposed. The Staunton, as it became known, became available to the general public on 29 September 1849. The Staunton style was soon the standard on which most tournament playing pieces have been made and used around the world ever since. The low cost of the Staunton set allowed the masses to purchase sets and helped to popularize the game of chess.


title: Staunton chess set

text: The Staunton set obtained the stamp of approval of FIDE, the World Chess Federation, when in 1924 it was selected as their choice of set, for use in all future international chess tournaments.


title: Staunton chess set

text: There are 17 recognized variants derived from the original 1849 Staunton chess set, classified as follows:


title: Staunton chess set

text: The Staunton chess set has proven to be extremely popular and is likely to remain so in the future. The design is successful because of its well-balanced and easily recognized pieces. It is currently the official standard for tournament chess pieces. Anthony Saidy and Norman Lessing wrote that, "if a vote were taken among chess-players as to which pieces they most enjoyed playing with, there can be no doubt that the Staunton chessmen would win by an overwhelming margin. They are invariably used in major chess tournaments. No self-respecting chess club would be without them. They afford the most pleasing combination of utility and aesthetic appeal."


title: Staunton chess set

text: Wooden Staunton chess sets were often turned on a lathe, then non-circular details were added by hand; the knights were made in two parts (head and base) which were stuck together with adhesive.


title: Staunton chess set

text: Even among sets of the standard Staunton pattern, the style of the pieces varies. The knights vary considerably. Some examples are shown below.


title: Bhumi (goddess)

text: Bhumi (), also known as Bhudevi and Vasundhara, is a Hindu goddess who is the personification of the Earth. She is a consort of the god Vishnu. According to Vaishnava tradition, she is the second aspect of Vishnu's consort, Lakshmi, along with the aspects of Sridevi and Niladevi. Varaha, the third avatar of Vishnu, saved her from the demon Hiranyaksha and later married her, making her one of his consorts. She is regarded as the mother of Narakasura, Mangala, and Sita.


title: Bhumi (goddess)

text: The name "Bhūmi" is Sanskrit word for "earth". The version "Puhumi" is the equivalent in Old Awadhi. She is known by various names such as Bhuvati, Bhuvani, Bhuvaneshwari, Avni, Prithvi, Varahi, Dharti, Dhaatri, Dharani, Vasudha, Vasundhara, Vaishnavi, Kashyapi, Urvi, Ira, Mahi, Ela, Vasumati, Dhanshika, Vasumati, Hema, and Hiranmaya.


title: Bhumi (goddess)

text: Bhudevi is depicted as seated on a platform that rests on the back of four elephants, representing the four cardinal directions. She is usually portrayed with four arms, holding a pomegranate, a water vessel, a bowl containing healing herbs, and another bowl containing vegetables, respectively. She is also sometimes depicted with two hands, the right hand holding a blue lotus known as Kumuda or Utpala, the night lotus, while the left hand may indicate the pose of Abhayamudra, the fearlessness or the Lolahasta Mudra, which is an aesthetic pose meant to mimic the tail of a horse.


title: Bhumi (goddess)

text: The episode of the devas seeking the assistance of Vishnu's Varaha avatar in rescuing Bhudevi is described in the Padma Purana:


title: Bhumi (goddess)

text: Prahlada, the son of Hiranyakashipu, was a devotee of Vishnu. The father did not like the son’s devotion to Vishnu. He punished Prahlada in a number of ways. Once, he threw down Prahlada from the top of a high building. At that moment, Bhudevi appeared there and received him in her arms.


title: Bhumi (goddess)

text: Bhudevi is the consort of the anthropomorphic Varaha, an avatar of Vishnu. In the Satya Yuga, the demon Hiranyaksha kidnapped her and hid her in the primordial waters, and Vishnu appeared as Varaha to rescue her. Varaha slew the demon and retrieved the Earth from the depths of the ocean, lifting it on his tusks. He restored Bhudevi to her rightful place in the universe, and proceeded to marry her. Mangala, and according to Vaishnava tradition, Narakasura, were the sons of Varaha and Bhumi.


title: Bhumi (goddess)

text: Narakasura was the first born of Bhudevi. There are two stories about Narakasura's birth. In the first one, he was the first son of Bhumi and Varaha. He was born when Bhumi requested Varaha for a son. Narakasura later performed a penance to receive a boon that only his mother would be able to kill him. In the second one, Narakasura's father was Hiranyaksha and was born when Hiranyaksha's horns touched Bhumi. Narakasura is believed to have been the founder of the legendary Bhauma dynasty among the Boro people.


title: Bhumi (goddess)

text: Sita, the wife of Rama, emerged from the earth, and thus Bhumi is her spiritual mother. The tale goes that there was once a drought in Mithila, the hometown of Sita. Janaka, the future father of Sita, was ploughing the ground. Under his plough, he found a baby girl (Sita). Rain showered upon the earth and Janaka and his wife, Sunaina, decided to adopt the girl. As Sita was born from the earth, she was also known as Bhumija.


title: Bhumi (goddess)

text: One of the most well-recounted legends of Bhumi is her episode with the emperor of the world, Prithu. When Prithu hears that his people are starving because the earth had withdrawn most of her vegetation, he furiously chases her in her form of a cow. She submits, allowing herself to be milked so that living beings could be nourished once more. Attributes such as the courage, valour, knowledge, and the bodily health of the Brahmin sages are stated to have been milked from the earth, and the virtues and the truths that characterise animals may be attributed to her as well:


title: Bhumi (goddess)

text: After receiving his desired boon, Narakasura grew arrogant and drunk with his power. He started capturing women and forcefully made them his wives. He captured nearly 16,000 women. He wrested control of heaven from Indra and no deity was able to defeat him because of his boon. Narakasura even took the earrings of Indra's mother, Aditi, and gave them to his mother, Bhumi. Bhudevi was requested by the devas to slay her son. She manifested herself upon the earth as Satyabhama, the daughter of Satrajit. Satyabhama married Krishna, and the couple waged war on Narakasura. She finally beheaded the latter with her husband's Sudarshana Chakra, thus fulfilling the prophecy that the asura could only be killed by his mother.


title: Aptronym

text: The "Encyclopædia Britannica" attributes the term to Franklin P. Adams, a writer who coined it as an anagram of "patronym", to emphasize "apt".


title: Aptronym

text: According to Frank Nuessel, in "The Study of Names" (1992), an "aptonym" is the term used for "people whose names and occupations or situations (e.g., workplace) have a close correspondence."


title: Aptronym

text: In the book "What's in a Name?" (1996), author Paul Dickson cites a long list of aptronyms originally compiled by Professor Lewis P. Lipsitt, of Brown University. Psychologist Carl Jung wrote in his book "Synchronicity" that there was a "sometimes quite grotesque coincidence between a man's name and his peculiarities".


title: Aptronym

text: Nominative determinism is a hypothesis which suggests a causal relationship based on the idea that people tend to be attracted to areas of work that fit their name.


title: Aptronym

text: Some aptronyms are ironic rather than descriptive, being called inaptronyms by Gene Weingarten of "The Washington Post".


title: Married at First Sight (British TV series)

text: Married at First Sight is a British television programme where couples are matched "scientifically" by a panel of "experts". They meet just minutes before they marry. Upon returning, they live together for a period of time, during which they meet at commitment ceremonies and choose whether or not they will continue their relationship. On 14 March 2021, Owen and Michelle from Series 5 became the first couple to celebrate their 1st wedding anniversary together.


text: On 24 November 2020, it was announced that the programme will move to Channel 4's sister channel E4 in 2021 and will use the format of its Australian counterpart following the highly successful broadcast of the latter on E4.


text: Following the success of Series 6, it has been recommissioned for a longer 30-episode seventh series.


text: After the success of the Australian version, the Australian format was adopted. In Episode 1, two couples (Bob & Megan and Ant & Nikita) were matched and married. In Episode 2, two couples (Matt & Dan and Luke & Morag) were matched and married. In Episode 4, two couples (Josh & Amy and Franky & Marilyse) met and were married. In Episode 5, the final two couples (Adam & Tayah and Jordon & Alexis) met and were married.


text: This series began on 30 August 2021. The final scheduled for 30 September 2021 was postponed after technical problems prevented it from being shown. The final episode was rescheduled the following day.


text: Official, 28-day consolidated ratings are taken from BARB and include E4 +1. Catch-up service totals are added to the official ratings.


text: For this series, a special aftershow was broadcast on Thursdays at 10pm, after the final "Married at First Sight" episode of the week.


text: After the success of the sixth series, an extended thirty-episode version using the same format was commissioned. This time, the cast included two same-sex couples - one male and one female. In each of Episodes 1, 2, 4 & 5, two couples were matched and married. In a franchise first, two additional couples were married and joined the experiment in Episode 12. The series began on August 29th, 2022, with the first episode followed by a "One Year Later" special episode with some of Series 6's cast. For this series, the Dinner Parties and Commitment Ceremonies moved from Brighton to Trinity Quay Wharf in London's Docklands.


text: Official, 7-day consolidated ratings are taken from Thinkbox and include E4 +1. From this series, 28-day ratings with viewership on devices other than televisions are no longer available, and so cannot be directly compared with the previous series.


text: A "One Year On" special, broadcast after the first episode on August 29, consolidated to 729,000 viewers.


title: Kang Kek Iew

text: Kang Kek Iew, also spelled Kaing Guek Eav (, ; 17 November 1942 – 2 September 2020), "nom de guerre" Comrade Duch (, ) or Hang Pin, was a Cambodian convicted war criminal and leader in the Khmer Rouge movement, which ruled Democratic Kampuchea from 1975 to 1979. As the head of the government's internal security branch (Santebal), he oversaw the Tuol Sleng (S-21) prison camp where thousands were held for interrogation and torture, after which the vast majority of these prisoners were eventually executed.


title: Kang Kek Iew

text: He was the first Khmer Rouge leader to be tried by the Extraordinary Chambers in the Courts of Cambodia for the crimes of the Khmer Rouge regime, and was convicted of crimes against humanity, murder, and torture for his role during the Khmer Rouge rule of Cambodia and sentenced to 30 years' imprisonment. On Candlemas Day, 2 February 2012, his sentence was extended to life imprisonment by the Extraordinary Chambers in the Courts of Cambodia.


title: Kang Kek Iew

text: Even though he was responsible for the death of thousands of people, Kang Kek Iew, unlike other Khmer Rouge cadres, did not dismiss or justify his crimes. He admitted that he had been wrong and that he had done horrible things; he said that he repented and that he had converted to Christianity. During his trial, he provided detailed accounts of what happened inside S-21 and inside the Khmer Rouge regime, and this helped shed light on the regime and other cadres' responsibility. Even though Kang's case was on appeal, his convictions stand as is the case with Nuon Chea.


title: Kang Kek Iew

text: Kang Kek Iew was born in Choyaot village, Kampong Chen subdistrict, Kampong Thom Province, to an ethnic Chinese family who migrated to Cambodia in his father's generation. A star pupil in his school, he passed his "Brevet d'études secondaires de première" in 1961 at the age of nineteen. He finished the first half of his Baccalaureate in 1962 at the Lycée Suravarman II in the town of Siem Reap. The same year he was offered a place in the prestigious Lycée Sisowath in Phnom Penh where he completed his Baccalaureate in mathematics, scoring second in the entire country.


title: Kang Kek Iew

text: From his childhood on, Kang's name was changed many times. One such occasion of name changing took place when he was 15, when his parents changed his name to Yim Cheav.


title: Kang Kek Iew

text: As the name is important in Chinese culture, Kang therefore gave his name to his grandson, significantly adding the Chinese name "Yun" to this name.


title: Kang Kek Iew

text: He was described by his former classmates as a bright and quiet boy who rarely smiled during his youth.


title: Kang Kek Iew

text: In 1964, Kek Iew began studying for his teaching certificate in Mathematics, a subject he loved, at the "Institut de Pédagogie". The institute was a cradle of activism under the directorship of Son Sen who was later to emerge as the Defence Minister of the Khmer Rouge and Duch's immediate superior.


title: Kang Kek Iew

text: On 28 August 1966, Kek Iew received his teaching certificate and was posted to a lycée in Skoun, a small town in Kampong Cham Province. He was a good teacher, remembered as earnest and committed by his pupils. He joined the Communist Party of Kampuchea in 1967. Following the arrest of three of his students, he fled to the Khmer Rouge base in Chamkar Leu District where he was accepted as a full member of the Communist Party of Kampuchea.


title: Kang Kek Iew

text: A few months later, he was arrested and witnessed others being tortured at the Prey Sar prison by Norodom Sihanouk's police for engaging in communist activities. He was held without trial for the next two years. In 1970, when he was released following the amnesty granted to political prisoners by Lon Nol, he joined the Khmer Rouge rebels in the Cardamom Mountains bordering Thailand.


title: Kang Kek Iew

text: Communist groups in France's former colonies in Indochina borrowed the French World War II expression 'maquis' when referring to their resistance movements in the jungles.


title: Kang Kek Iew

text: In the zone under the control of the Khmer Rouge, Kek Iew took on his "nom de guerre" Comrade Duch (IPA:[dujc]) and became a prison commandant. He was appointed the head of Special Security by his immediate superior Vorn Vet. In the forests of Amleang, Thpong District, Duch set up his first prison, code-named 'M-13'. Two years later, he also established a second prison 'M-99' in the nearby Aoral District.


title: Kang Kek Iew

text: Assisted by his two deputies, Mam Nai (Comrade Chan) and Tang Sin Hean (Comrade Pon), Duch began perfecting his interrogation techniques and the purging of perceived enemies from the Khmer Rouge ranks. Prisoners at these camps, mostly from the ranks of the Khmer Rouge, were routinely starved and tortured to extract real and made-up confessions.


title: Kang Kek Iew

text: While in the maquis, Duch married Chhim Sophal, aka Rom, a dressmaker from a nearby village. They had four children while he worked at S-21.


title: Kang Kek Iew

text: After the Khmer Rouge victory in April 1975, Duch and his men set up prisons throughout the capital, including the infamous Tuol Sleng prison. Duch's request for a transfer in May 1975 to the Industrial Sector of government was denied. The Tuol Sleng prison camp was initially headed by In Lon (aka Comrade Nath) with Duch acting as deputy. Subsequently, In Lon was transferred and Duch was promoted to Director. By May 1976, all the prisons in Phnom Penh were consolidated and relocated to Tuol Sleng.


title: Kang Kek Iew

text: Prisons like Tuol Sleng were created to cleanse the population of suspected enemies of the revolution. In Tuol Sleng, Duch ordered the execution of prisoners after their interrogation was completed. For example, on a list containing the names of 17 prisoners (eight teenagers and nine children), he wrote the order "Smash them to pieces." On a longer list of detainees, his annotation reads "smash: 115; keep: 44 persons." The text below this annotation reads "Comrade Duch proposed to Angkar; Angkar agreed." On a list of 20 female detainees, Duch wrote annotations for each of them, ordering: "take away for execution," "keep for interrogation" or "medical experiment". At least 100 detainees died after having all of their blood drawn for transfusions for wounded soldiers. Surgical operations were also performed on detainees in order to train medical staff.


title: Kang Kek Iew

text: Duch impressed his superiors with his work and was appointed the head of Democratic Kampuchea's dreaded "special branch"; the Santebal.


title: Kang Kek Iew

text: As the party purges increased toward the end of the Democratic Kampuchea period, more people were brought to Duch, including former colleagues, among them his predecessor at Tuol Sleng, In Lon. Throughout this period, Duch built up a large archive of prison records, mug shots, and extracted "confessions".


title: Kang Kek Iew

text: On 6 January 1979, he was ordered by his superior to kill the remaining prisoners. The next day, Duch was among the last Khmer Rouge cadres to flee Phnom Penh after it fell to the Vietnamese army. Though he was unable to destroy much of the prison's extensive documents, he saw to the execution of several surviving prisoners before he fled the city.


title: Kang Kek Iew

text: Duch reached the border of Thailand in May 1979. Details of his whereabouts at this time remain unclear. It is believed that he went to the forests of Samlaut where he was reunited with his family. Here Duch was demoted by Brother Number Two, Nuon Chea, for having failed to destroy the documents at Tuol Sleng. At the border, he learned to speak Thai and taught himself English. He later taught English and mathematics at a refugee camp in Borai just inside Thailand.


title: Kang Kek Iew

text: In June 1986, Duch was sent to China to teach as a Khmer language expert at the Beijing Foreign Language Institute. He returned to the Thai-Cambodian border a year later and changed his name to Hang Pin. He worked as a senior bureaucrat just inside the Cambodian border at Pol Pot's secretariat at Camp 505. Shortly after the Paris agreement in October 1991, he moved with his family to the small isolated village of Phkoam close to the Thai border. Here he purchased some land, and began teaching in the local school. He was known as a good teacher, but one with a fiery temper.


title: Kang Kek Iew

text: In 1995, Duch's wife was killed under mysterious circumstances in an attack on his home. Duch was the only witness and suspected Pol Pot of instigating it. He sold all his possessions, secured a transfer to Svay Chek College, and moved there with his children. Shortly after his wife's murder, Duch began attending the prayer meetings of the Golden West Cambodian Christian Church held in Battambang by Christopher LaPel, an evangelical Khmer-American. Duch was baptized by LaPel and eventually became a lay pastor. LaPel was later to observe that although he did not know Duch's real identity at the time, there were clues. For example, before his conversion, Duch had said to LaPel that he had done a lot of bad things in his life. Later, Duch was to say, "I don’t know if my brothers and sisters can forgive the sins I've committed against the people".


title: Kang Kek Iew

text: Soon after his identity was discovered, Duch accepted a transfer to Samlaut as Director of Education. When fighting broke out in 1996 following the split of the Khmer Rouge and the coup to oust Prince Rannariddh in 1997, he fled with his family to the Ban Ma Muang camp just inside Thailand. At the camp, he worked for the American Refugee Committee as the Community Health Supervisor. In late 1998, he returned to Cambodia when fighting subsided. He settled in the village of Andao Hep in Rattanak Mondul and worked closely with World Vision International, the Christian relief agency.


title: Kang Kek Iew

text: The photojournalist Nic Dunlop tracked Duch down in Samlaut. In 1999, Nate Thayer, who had previously interviewed Pol Pot and Ta Mok, and Dunlop interviewed Duch for the "Far Eastern Economic Review". Duch surrendered to the authorities in Phnom Penh following the publication of this interview.


title: Kang Kek Iew

text: On 31 July 2007, Duch was formally charged with war crimes and crimes against humanity and detained by Cambodia's United Nations-backed Extraordinary Chambers in the Courts of Cambodia. Duch, represented by Cambodian lawyer Kar Savuth and French lawyer François Roux, appealed against his provisional detention by the Extraordinary Chambers in the Courts of Cambodia based on the more than eight years he spent without trial in Cambodian military detention. The appeal was unsuccessful and on 14 August 2008, the tribunal issued its indictment after completing their investigation of Duch.


title: Kang Kek Iew

text: In February 2008, as part of the judicial process, Duch was taken to Tuol Sleng prison, the scene of his crimes. He reportedly collapsed in tears after stating, "I ask for your forgiveness – I know that you cannot forgive me, but I ask you to leave me the hope that you might."


title: Kang Kek Iew

text: On 16 February 2009, the UN supervised trial of Duch began at a Phnom Penh court. Duch was prosecuted by international co-prosecutors William Smith and Anees Ahmed and was charged with "personally overseeing the systematic torture of more than 15,000 prisoners." The presiding judge of the case was Nil Nonn. Duch was tried by a panel of five judges — three Cambodian, one French, and one New Zealander — according to a 2003 pact between Cambodia and the United Nations establishing the tribunal.


title: Kang Kek Iew

text: On 31 March 2009, Duch, in a statement in front of the Cambodia tribunal, accepted responsibility for torturing and executing thousands of inmates, expressed "heartfelt sorrow" for his crimes and vowed to cooperate fully with the tribunal.


title: Kang Kek Iew

text: Duch surprised the tribunal on 27 November 2009 with a plea to be released. In his final statement before the tribunal he acknowledged his involvement in Khmer Rouge-era crimes, including the execution of more than 12,000 Tuol Sleng prisoners, but said they were committed by a "criminal party". Duch also noted that he had served more than 10 years in detention, and stressed that he had been fully cooperative with the tribunal. There were also conflicting closing arguments from Duch's defense team. His Cambodian lawyer, Kar Savuth demanded his client's acquittal and release, while his international counterpart, François Roux pressed judges to hand down a lenient sentence.


title: Kang Kek Iew

text: At the conclusion of the trial, prosecutors asked that Duch be given 40 years in prison if convicted. On 26 July 2010, Duch was found guilty of crimes against humanity, torture, and murder; he was sentenced to 35 years imprisonment, with a pre-trial detention credit of 11 years being applied to his sentence and an additional controversial five-year deduction because his period of pre-trial detention exceeded the maximum allowed under Cambodian law. On 3 February 2012, an upper court U.N. war crimes tribunal rejected his appeal and extended his sentence to life imprisonment because of his "shocking and heinous" crimes. The ruling was final with no other chance for appeal.


title: Kang Kek Iew

text: After serving ten years in prison, on 2 September 2020, Duch died at the age of 77 at the Khmer–Soviet Friendship Hospital of chronic obstructive pulmonary disease. Due to the complicated situation of COVID-19 in Cambodia, he was quickly cremated on the same day in Phnom Penh, without a Buddhist funeral.


title: Heritability

text: Heritability is a statistic used in the fields of breeding and genetics that estimates the degree of "variation" in a phenotypic trait in a population that is due to genetic variation between individuals in that population. The concept of heritability can be expressed in the form of the following question: "What is the proportion of the variation in a given trait within a population that is "not" explained by the environment or random chance?"


title: Heritability

text: Other causes of measured variation in a trait are characterized as environmental factors, including observational error. In human studies of heritability these are often apportioned into factors from "shared environment" and "non-shared environment" based on whether they tend to result in persons brought up in the same household being more or less similar to persons who were not.


title: Heritability

text: Heritability is estimated by comparing individual phenotypic variation among related individuals in a population, by examining the association between individual phenotype and genotype data, or even by modeling summary-level data from genome-wide association studies (GWAS). Heritability is an important concept in quantitative genetics, particularly in selective breeding and behavior genetics (for instance, twin studies). It is the source of much confusion due to the fact that its technical definition is different from its commonly-understood folk definition. Therefore, its use conveys the incorrect impression that behavioral traits are "inherited" or specifically passed down through the genes. Behavioral geneticists also conduct heritability analyses based on the assumption that genes and environments contribute in a separate, additive manner to behavioral traits.


title: Heritability

text: Heritability measures the fraction of phenotype variability that can be attributed to genetic variation. This is not the same as saying that this fraction of an individual phenotype is caused by genetics. For example, it is incorrect to say that since the heritability of personality traits is about 0.6, that means that 60% of your personality is inherited from your parents and 40% comes from the environment. In addition, heritability can change without any genetic change occurring, such as when the environment starts contributing to more variation. As a case in point, consider that both genes and environment have the potential to influence intelligence. Heritability could increase if genetic variation increases, causing individuals to show more phenotypic variation, like showing different levels of intelligence. On the other hand, heritability might also increase if the environmental variation decreases, causing individuals to show less phenotypic variation, like showing more similar levels of intelligence. Heritability increases when genetics are contributing more variation or because non-genetic factors are contributing less variation; what matters is the relative contribution. Heritability is specific to a particular population in a particular environment. High heritability of a trait, consequently, does not necessarily mean that the trait is not very susceptible to environmental influences. Heritability can also change as a result of changes in the environment, migration, inbreeding, or the way in which heritability itself is measured in the population under study. The heritability of a trait should not be interpreted as a measure of the extent to which said trait is genetically determined in an individual.


title: Heritability

text: The extent of dependence of phenotype on environment can also be a function of the genes involved. Matters of heritability are complicated because genes may canalize a phenotype, making its expression almost inevitable in all occurring environments. Individuals with the same genotype can also exhibit different phenotypes through a mechanism called phenotypic plasticity, which makes heritability difficult to measure in some cases. Recent insights in molecular biology have identified changes in transcriptional activity of individual genes associated with environmental changes. However, there are a large number of genes whose transcription is not affected by the environment.


title: Heritability

text: Estimates of heritability use statistical analyses to help to identify the causes of differences between individuals. Since heritability is concerned with variance, it is necessarily an account of the differences between individuals in a population. Heritability can be univariate – examining a single trait – or multivariate – examining the genetic and environmental associations between multiple traits at once. This allows a test of the genetic overlap between different phenotypes: for instance hair color and eye color. Environment and genetics may also interact, and heritability analyses can test for and examine these interactions (GxE models).


title: Heritability

text: A prerequisite for heritability analyses is that there is some population variation to account for. This last point highlights the fact that heritability cannot take into account the effect of factors which are invariant in the population. Factors may be invariant if they are absent and do not exist in the population, such as no one having access to a particular antibiotic, or because they are omni-present, like if everyone is drinking coffee. In practice, all human behavioral traits vary and almost all traits show some heritability.


title: Heritability

text: In a planned experiment Cov("G","E") can be controlled and held at 0. In this case, heritability, formula_1 is defined as


title: Heritability

text: "H" is the broad-sense heritability. This reflects all the genetic contributions to a population's phenotypic variance including additive, dominant, and epistatic (multi-genic interactions), as well as maternal and paternal effects, where individuals are directly affected by their parents' phenotype, such as with milk production in mammals.


title: Heritability

text: A particularly important component of the genetic variance is the additive variance, Var(A), which is the variance due to the average effects (additive effects) of the alleles. Since each parent passes a single allele per locus to each offspring, parent-offspring resemblance depends upon the average effect of single alleles. Additive variance represents, therefore, the genetic component of variance responsible for parent-offspring resemblance. The additive genetic portion of the phenotypic variance is known as Narrow-sense heritability and is defined as


title: Heritability

text: For traits which are not continuous but dichotomous such as an additional toe or certain diseases, the contribution of the various alleles can be considered to be a sum, which past a threshold, manifests itself as the trait, giving the liability threshold model in which heritability can be estimated and selection modeled.


title: Heritability

text: Additive variance is important for selection. If a selective pressure such as improving livestock is exerted, the response of the trait is directly related to narrow-sense heritability. The mean of the trait will increase in the next generation as a function of how much the mean of the selected parents differs from the mean of the population from which the selected parents were chosen. The observed "response to selection" leads to an estimate of the narrow-sense heritability (called realized heritability). This is the principle underlying artificial selection or breeding.


title: Heritability

text: The simplest genetic model involves a single locus with two alleles (b and B) affecting one quantitative phenotype.


title: Heritability

text: The number of B alleles can be 0, 1, or 2. For any genotype, ("B","B"), where "B" and "B" are either 0 or 1, the expected phenotype can then be written as the sum of the overall mean, a linear effect, and a dominance deviation (one can think of the dominance term as an "interaction" between "B" and "B"):


title: Heritability

text: The additive genetic variance at this locus is the weighted average of the squares of the additive effects:


title: Heritability

text: Estimates of the total heritability of human traits assume the absence of epistasis, which has been called the "assumption of additivity". Although some researchers have cited such estimates in support of the existence of "missing heritability" unaccounted for by known genetic loci, the assumption of additivity may render these estimates invalid. There is also some empirical evidence that the additivity assumption is frequently violated in behavior genetic studies of adolescent intelligence and academic achievement.


title: Heritability

text: Since only "P" can be observed or measured directly, heritability must be estimated from the similarities observed in subjects varying in their level of genetic or environmental similarity. The statistical analyses required to estimate the genetic and environmental components of variance depend on the sample characteristics. Briefly, better estimates are obtained using data from individuals with widely varying levels of genetic relationship - such as twins, siblings, parents and offspring, rather than from more distantly related (and therefore less similar) subjects. The standard error for heritability estimates is improved with large sample sizes.


title: Heritability

text: In non-human populations it is often possible to collect information in a controlled way. For example, among farm animals it is easy to arrange for a bull to produce offspring from a large number of cows and to control environments. Such experimental control is generally not possible when gathering human data, relying on naturally occurring relationships and environments.


title: Heritability

text: In classical quantitative genetics, there were two schools of thought regarding estimation of heritability.


title: Heritability

text: One school of thought was developed by Sewall Wright at The University of Chicago, and further popularized by C. C. Li (University of Chicago) and J. L. Lush (Iowa State University). It is based on the analysis of correlations and, by extension, regression. Path Analysis was developed by Sewall Wright as a way of estimating heritability.


title: Heritability

text: The second was originally developed by R. A. Fisher and expanded at The University of Edinburgh, Iowa State University, and North Carolina State University, as well as other schools. It is based on the analysis of variance of breeding studies, using the intraclass correlation of relatives. Various methods of estimating components of variance (and, hence, heritability) from ANOVA are used in these analyses.


title: Heritability

text: Today, heritability can be estimated from general pedigrees using linear mixed models and from genomic relatedness estimated from genetic markers.


title: Heritability

text: Studies of human heritability often utilize adoption study designs, often with identical twins who have been separated early in life and raised in different environments. Such individuals have identical genotypes and can be used to separate the effects of genotype and environment. A limit of this design is the common prenatal environment and the relatively low numbers of twins reared apart. A second and more common design is the twin study in which the similarity of identical and fraternal twins is used to estimate heritability. These studies can be limited by the fact that identical twins are not completely genetically identical, potentially resulting in an underestimation of heritability.


title: Heritability

text: In observational studies, or because of evocative effects (where a genome evokes environments by its effect on them), G and E may covary: gene environment correlation. Depending on the methods used to estimate heritability, correlations between genetic factors and shared or non-shared environments may or may not be confounded with heritability.


title: Heritability

text: where "r" can be thought of as the coefficient of relatedness, "b" is the coefficient of regression and "t" is the coefficient of correlation.


title: Heritability

text: Heritability may be estimated by comparing parent and offspring traits (as in Fig. 2). The slope of the line (0.57) approximates the heritability of the trait when offspring values are regressed against the average trait in the parents. If only one parent's value is used then heritability is twice the slope. (Note that this is the source of the term "regression," since the offspring values always tend to regress to the mean value for the population, "i.e.", the slope is always less than one). This regression effect also underlies the DeFries–Fulker method for analyzing twins selected for one member being affected.


title: Heritability

text: A basic approach to heritability can be taken using full-Sib designs: comparing similarity between siblings who share both a biological mother and a father. When there is only additive gene action, this sibling phenotypic correlation is an index of "familiarity" – the sum of half the additive genetic variance plus full effect of the common environment. It thus places an upper limit on additive heritability of twice the full-Sib phenotypic correlation. Half-Sib designs compare phenotypic traits of siblings that share one parent with other sibling groups.


title: Heritability

text: Heritability for traits in humans is most frequently estimated by comparing resemblances between twins. "The advantage of twin studies, is that the total variance can be split up into genetic, shared or common environmental, and unique environmental components, enabling an accurate estimation of heritability". Fraternal or dizygotic (DZ) twins on average share half their genes (assuming there is no assortative mating for the trait), and so identical or monozygotic (MZ) twins on average are twice as genetically similar as DZ twins. A crude estimate of heritability, then, is approximately twice the difference in correlation between MZ and DZ twins, i.e. Falconer's formula "H"=2(r(MZ)-r(DZ)).


title: Heritability

text: The effect of shared environment, "c", contributes to similarity between siblings due to the commonality of the environment they are raised in. Shared environment is approximated by the DZ correlation minus half heritability, which is the degree to which DZ twins share the same genes, "c"=DZ-1/2"h". Unique environmental variance, "e", reflects the degree to which identical twins raised together are dissimilar, "e"=1-r(MZ).


title: Heritability

text: The second set of methods of estimation of heritability involves ANOVA and estimation of variance components.


title: Heritability

text: We use the basic discussion of Kempthorne. Considering only the most basic of genetic models, we can look at the quantitative contribution of a single locus with genotype G as


title: Heritability

text: Consider an experiment with a group of sires and their progeny from random dams. Since the progeny get half of their genes from the father and half from their (random) mother, the progeny equation is


title: Heritability

text: Consider the experiment above. We have two groups of progeny we can compare. The first is comparing the various progeny for an individual sire (called "within sire group"). The variance will include terms for genetic variance (since they did not all get the same genotype) and environmental variance. This is thought of as an "error" term.


title: Heritability

text: The second group of progeny are comparisons of means of half sibs with each other (called "among sire group"). In addition to the error term as in the within sire groups, we have an addition term due to the differences among different means of half sibs. The intraclass correlation is


title: Heritability

text: In an experiment with formula_15 sires and formula_16 progeny per sire, we can calculate the following ANOVA, using formula_17 as the genetic variance and formula_18 as the environmental variance:


title: Heritability

text: The formula_19 term is the intraclass correlation between half sibs. We can easily calculate formula_20. The expected mean square is calculated from the relationship of the individuals (progeny within a sire are all half-sibs, for example), and an understanding of intraclass correlations.


title: Heritability

text: The use of ANOVA to calculate heritability often fails to account for the presence of gene–-environment interactions, because ANOVA has a much lower statistical power for testing for interaction effects than for direct effects.


title: Heritability

text: formula_22 is the additive effect of the i allele, formula_23 is the additive effect of the j allele, formula_24 is the dominance deviation for the ij genotype, and formula_12 is the environment.