document_title: Field goal

question_text: who holds the record for the longest field goal in nfl history

text: Field goal

text: Strategy[edit]

text: As a field goal is worth only three points, while a touchdown scores at least six (which usually becomes seven with a successful conversion, and potentially 8 with a two-point conversion), teams will generally attempt a field goal only in the following situations:

text:
It is fourth down (third down in Canadian rules), especially if the offense is more than a yard or two from a new first down, and within about 45 yards of the goal posts.
In the first half, there is enough time remaining to execute only one more play.
In the second half, there is enough time remaining to execute only one more play, and the team on offense needs three points to win or tie (four points in a few leagues given special circumstances).
The game is in overtime, and a FG is the quickest, easiest, and least risky way to end the match.

text: Except in desperate situations, a team will generally attempt field goals only when keeping a drive alive is unlikely, and its kicker has a significant chance of success, as a missed field goal results in a turnover at the spot of the kick (in the NFL) or at the line of scrimmage (in the NCAA). In American high school rules and Canadian football, where a missed field goal is treated the same as a punt, most teams still opt not to attempt field goals from very long range since field goal formations are not conducive to covering kick returns. Even under ideal conditions, the best professional kickers historically had difficulty making kicks longer than 50 yards consistently (the NFL record is 64 yards and the CFL record, 62 yards).[2] If a team chooses not to attempt a field goal on their last down, they can punt to the other team. A punt cannot score any points in American football unless the receiving team touches the ball first and the kicking team recovers it (though it can result in a single in Canadian football), but it may push the other team back toward its own end.

text: The longest field goal kick in NFL history is 64 yards, a record set by Matt Prater on December 8, 2013. The previous record was 63, originally set by Tom Dempsey and then matched by Jason Elam, Sebastian Janikowski, and David Akers. High school, college and most professional football leagues offer only a three-point field goal; however, some professional leagues have encouraged more rare kicks through four-point field goals. NFL Europe encouraged long field goals of 50 yards or more by making those worth four points instead of three (much like Australian rules' Super Goal or basketball's three-point line), a rule since adopted by the Stars Football League. Similarly, the sport of arena football sought (unsuccessfully) to repopularize the drop kick by making that worth four points; it failed, since only one kicker (Brian Mitchell) was able to do it with any semblance of proficiency. (In six-man football, where there is no offensive line, all field goals are worth four points instead of the usual three.)

text: The overall field goal percentage during the 2010 NFL season was 82.3. In comparison, Jan Stenerud, one of only two pure kickers in the Pro Football Hall of Fame (along with Ray Guy), had a career field goal percentage of 66.8 from 1967 to 1985.[2]

text: How field goals are kicked[edit]

text: When a team decides to attempt a field goal, it will generally line up in a very tight formation, with all but two players lined up along or near the line of scrimmage: the placekicker and the holder. The holder is usually the team's punter or backup quarterback.[citation needed] Instead of the regular center, a team may have a dedicated long snapper trained especially to snap the ball on placekick attempts and punts.

text: The holder usually lines up seven to eight yards behind the line of scrimmage, with the kicker a few yards behind him. Upon receiving the snap, the holder holds the ball against the ground vertically, with the stitches away from the kicker. The kicker begins his approach during the snap, so the snapper and holder have little margin for error. A split-second mistake can disrupt the entire attempt.

text: The measurement of a field goal's distance is from the goalpost to the point where the ball was positioned for the kick by the holder. In American football, where the goalpost is located at the back of the end zone (above the end line), the ten yards of the end zone are added to the yard line distance at the spot of the hold.

text: Until the 1960s, placekickers approached the ball straight on, with the toe making first contact with the ball. The technique of kicking the ball "soccer-style", by approaching the ball at an angle and kicking it with the instep, was introduced by Hungarian-born kicker Pete Gogolak in the 1960s.[3] Reflecting his roots in European soccer, Gogolak observed that kicking the ball at an angle could cover more distance than kicking straight-on; he played college football at Cornell and made his pro debut in 1964 with the Buffalo Bills of the AFL; his younger brother Charlie was also an NFL kicker. The soccer-style kick gained popularity and was nearly universal by the late 1970s; the last straight-on kicker in the NFL was Mark Moseley, who retired 32 years ago in 1986.

text: Successful field goals[edit]

text: If there is any time left in the half, the method of resuming play after a successful field goal varies between leagues.

text: Missed field goals[edit]

text: A missed field goal is said to be "no good" if the kicked ball does not cross between the uprights and/or over the crossbar of the goal posts. If it misses to the posts' left it may be called "wide left" and "wide right" if it misses to the posts' right. A field goal attempt may be described as "short" if it does not have sufficient distance to go over the cross bar. Some commentators will only describe a field goal attempt as being short if it appears to have been aimed correctly while others will describe an attempt appearing to lack both accuracy and distance as being both wide and short.

text: If a field goal attempt is missed and does not go out of bounds, a defensive player may catch the ball and return it, like a punt or kickoff. This type of play usually occurs during an extremely long field goal attempt due to the distance the defense must travel to reach the returner. If there is a significant likelihood of a miss and the strategic game situation warrants it, the defense places a player downfield, in or near their end zone, to catch the ball. The risk in this is that the return man may be tackled deep in his own territory, at a considerably worse position than he could have gotten by letting the ball go dead (see below); furthermore, should the returner fumble the ball, the kicking team can recover it and gain a new set of downs (the advantage is that the kicking team is lined up very close together to stop kick blockers, and not spread across the field like a kickoff or punt team, and is therefore in poor position to defend the return). Thus, teams will usually return a kick only towards the end of a half (when the kick will be the final play) or in a particularly desperate situation.

text: If a ball caroms off one of the goal posts or the crossbar, but lands in the field of play, the ball is considered dead and cannot be returned. (This is not the case in arena football, where large "rebound nets" surround the goal posts for the explicit purpose of keeping the ball in play.) However, if the ball caroms off one of the goal posts or the crossbar and continues into the goal, the score counts.

text: Situations where the defense does not return a missed field goal vary between leagues and levels of play:

text: Blocked field goals[edit]

text: Occasionally, the defense will succeed in blocking a field goal. If a blocked field goal is in or behind the neutral zone, it is treated like a fumble and can be advanced by either team. Beyond the neutral zone, a blocked kick is treated like a punt and can be advanced only by the defense, unless a defensive player fumbles the ball, after which an offensive player can advance it.

text: History[edit]

text: In the early days of football, kicking was highly emphasized. In 1883, the scoring system was devised, with field goals counting for 5 points, and touchdowns and conversions worth 4 apiece. In 1897, the touchdown was raised to 5 points while the conversion was lowered to 1 point. Field goals were devalued to 4 points in 1904, and then to the modern 3 points in 1909. The touchdown was changed to 6 points in 1912 in American football; the Canadian game followed suit in 1956.

text: The spot of the conversion has also changed through the years. In 1924, NCAA rules spotted the conversion at the 3-yard line, before moving it back to the 5-yard line in 1925. In 1929, the spot was moved up to the 2-yard line, which the NFL had done until 2014. In 1968, the NCAA diverged from the NFL rules in moving the spot back to the original 3-yard line. Canadian rules originally spotted the conversion at the 5-yard line, which remains closer than in the American code as the goalposts are at the front of the end zone. In 2015, to make conversion kicks harder, the NFL and CFL moved the spot of the kick to the 15 and 25-yard lines, respectively. In addition, the CFL moved the spot for a two-point conversion up to the 3-yard line to entice more teams to go for 2 points as opposed to one.

text: The goalposts were originally located on the goal line; this led to many injuries and sometimes interfered with play. The NCAA moved the goal posts to the rear of the end zone in 1927. The NFL (still following NCAA rules at the time) followed suit, but moved the posts back to the goal line starting in the 1932 NFL Playoff Game, a change made necessary by the size of the indoor Chicago Stadium and kept when the NFL rules stopped mirroring the NCAA rules in 1933. The NFL kept the post at the goal line until 1974, when they were moved back to the rear of the end zone. This was partly a result of the narrowed hashmark distance made in 1972, which had made for easier field-goal angles. The Canadian game still has posts on the goal line.

text: The width of the goalposts and the hashmarks have also varied throughout the years. In 1959, the NCAA goalposts were widened to 23 feet 4 inches (7.11 m), the standard width for high school posts today. In 1991, the college goalposts were reduced in width to 18 ft 6 in (5.64 m), matching the NFL. For the 1991 and 1992 seasons, this meant potentially severe angles for short field goal attempts, since the hashmark width remained at 53 ft 4 in (16.26 m). In 1993, the NCAA narrowed the distance between the hashmarks to 40 ft (12.19 m), matching what was the width of hashmarks in the NFL from 1945 through 1971; the NFL narrowed the hashmarks in 1972 to goalpost width at 18.5 feet (5.64 m). In the CFL, the hashmarks are 51 feet (16 m), but the field is 195 feet (59 m) in width, 35 feet (11 m) wider than the American field.

text: The NFL increased the height of the uprights above the crossbar to 20 feet (6.10 m) in 1966 and 30 feet (9.14 m) in 1974. In 2014, they were raised five feet to 35 feet (10.67 m) after the adoption of a proposal by New England Patriots head coach Bill Belichick.[7]

text: The "slingshot" goalpost, with a single post curving to support the crossbar, was invented by Jim Trimble and Joel Rottman in Montreal, Quebec, Canada.[8] The first were built by Alcan and displayed at Expo 67,[8][9] the World's fair in Montreal. The NFL had standardized the goalposts in 1966 and adopted the slingshot for the 1967 season;[8] the NCAA later adopted the same rule, but later allowed the use of "offset" goalposts, with two posts rather than one (which were the norm prior to the invention of the "slingshot" goalposts). The CFL was the first league to use the new goalposts; they made their debut in the 2nd game of the CFL's Eastern Conference final in 1966 (which was played at Montreal's Autostade as Landsdowne Park [now TD Place Stadium], the home of Ottawa Rough Riders, was undergoing renovations), and were used in the Grey Cup the next week at Vancouver's Empire Stadium. Three schools in Division I FBS currently use dual-support posts: Florida State, LSU, and Washington State. A special exemption was allowed by the NFL for the New Orleans Saints to use the offset goalposts during the 2005 season, when they used LSU's stadium for home games after Hurricane Katrina.

text: Goalposts at the professional level today are sometimes equipped with a camera mounted to the stanchion immediately behind the center of the crossbar. Since these cameras are both above and slightly behind the crossbar, a field goal attempt will be judged good if it strikes this equipment.

text: In 1989, the NCAA banned the kicking tee for field goals and extra points, requiring kicks from the ground.[10][11]

text: During the 2011 NFL season, a record 90 field goals of 50 yards or longer were made.[12] In 2012, this record was increased to 92 field goals of 50 yards or longer.[12]

text: Longest field goal records[edit]

text: This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (May 2010) (Learn how and when to remove this template message)

text: As recorded in Guinness World Records:

text: The record for a field goal at any level is 69 yards. It was kicked by Ove Johansson of the Abilene Christian University Wildcats in the 1976 game against East Texas State University Lions (now Texas A&M University–Commerce) in Shotwell Stadium, Abilene, Texas.[13]

text: NFL[edit]

text: The longest field goal made was 64 yards by Matt Prater of the Denver Broncos on December 8, 2013.[14] The longest field goal attempt in an NFL game was 76 yards by Sebastian Janikowski on September 28, 2008.[15]

text: In the history of the NFL regular season, only 18 field goals have been made from at least 60 yards:[16]

text:
Distance
Kicker
Team
Result
Opposition
Date
Notes
Location
Elevation
Weather

64 yards
Matt Prater
Denver Broncos
51–28
Tennessee Titans
December 8, 2013
End of 1st half
Sports Authority Field at Mile High
5,280 ft (1,610 m)
13 °F; Sunny; Wind: S at 3 mph; Humidity: 72%

63 yards
Tom Dempsey
New Orleans Saints
19–17
Detroit Lions
November 8, 1970
Born with a stub for a right foot. Game-winning kick as time expired. Detroit kicker Errol Mann had kicked a field goal with :08 remaining to give Lions the lead.
Tulane Stadium
16 ft (4.9 m)

63 yards
Jason Elam
Denver Broncos
37–24
Jacksonville Jaguars
October 25, 1998
First field goal to tie record; soccer-style kicker
Mile High Stadium
5,280 ft (1,610 m)

63 yards
Sebastian Janikowski
Oakland Raiders
23–20
Denver Broncos
September 12, 2011
Left-footed
Sports Authority Field at Mile High
5,280 ft (1,610 m)
Light rain early

63 yards
David Akers
San Francisco 49ers
30–22
Green Bay Packers
September 9, 2012
Left-footed; end of first half; ball bounced off crossbar before crossing the plane
Lambeau Field
640 ft (200 m)
70 °F; Mostly Cloudy; Wind: N at 7 mph; Humidity: 43%

62 yards
Matt Bryant
Tampa Bay Buccaneers
23–21
Philadelphia Eagles
October 22, 2006
Game-winning kick as time expired
Raymond James Stadium
35 ft (11 m)

62 yards
Stephen Gostkowski
New England Patriots
33–8
Oakland Raiders
November 19, 2017
Right-footed; kicked as time expired at the end of the first half
Azteca Stadium
7,280 ft (2,220 m)
63 °F; Mostly Cloudy

61 yards
Sebastian Janikowski
Oakland Raiders
9–23
Cleveland Browns
December 27, 2009
Left-footed
FirstEnergy Stadium
580 ft (180 m)

61 yards
Jay Feely
Arizona Cardinals
16–19 (OT)
Buffalo Bills
October 14, 2012
Right-footed; longest game-tying field goal with 1:09 remaining in the 4th quarter, missed a 38-yard field goal that would have won the game at the end of regulation
University of Phoenix Stadium
1,150 ft (350 m)
Retractable roof closed

61 yards
Justin Tucker
Baltimore Ravens
18–16
Detroit Lions
December 16, 2013
Right-footed; game-winning field goal with 43 seconds remaining; sixth field goal of the game
Ford Field
601 ft (183 m)[17]
Dome

61 yards
Greg Zuerlein
St. Louis Rams
18–21 (OT)
Minnesota Vikings
November 8, 2015
Right-footed
TCF Bank Stadium
869 ft (265 m)
58 °F (14 °C); sunny

61 yards
Jake Elliott
Philadelphia Eagles
27–24
New York Giants
September 24, 2017
Right-footed; game winning kick as time expired. Second game of NFL career. NFL rookie record for longest made field goal.
Lincoln Financial Field
39 ft (12 m)
91 °F (33 °C); sunny

60 yards
Steve Cox
Cleveland Browns
9–12
Cincinnati Bengals
October 21, 1984
Straight-ahead kick; on AstroTurf
Riverfront Stadium
490 ft (150 m)

60 yards
Morten Andersen
New Orleans Saints
17–20
Chicago Bears
October 27, 1991
Left-footed; on AstroTurf; first 60-yard kick done indoors
Louisiana Superdome
Sea level
Dome

60 yards
Rob Bironas
Tennessee Titans
20–17
Indianapolis Colts
December 3, 2006
Right-footed; game winner with six seconds remaining
LP Field
400 ft (120 m)

60 yards
Dan Carpenter
Miami Dolphins
10–13
Cleveland Browns
December 5, 2010
End of 1st half
Sun Life Stadium
5 ft (1.5 m)
77 °F (25 °C), wind SW at 14 mph (23 km/h)

60 yards
Greg Zuerlein
St. Louis Rams
19–13
Seattle Seahawks
September 30, 2012
In his rookie season; longest field goal in third quarter; also kicked a 58-yard field goal in the first quarter
Edward Jones Dome
466 ft (142 m)
Dome

60 yards
Chandler Catanzaro
Arizona Cardinals
18–33
Buffalo Bills
September 25, 2016
Longest field goal in career
New Era Field
600 ft (180 m)

text: Prior to Dempsey's 1970 kick, the longest field goal in NFL history was a 56-yard field goal by Bert Rechichar in 1953. A 55-yard field goal, achieved by a drop kick, was recorded by Paddy Driscoll in 1924, and stood as the unofficial record until that point; some sources indicate a 54-yarder by Glenn Presnell in 1934 as the record, due to the inability to precisely verify Driscoll's 55-yarder.

text: In a pre-season NFL game between the Denver Broncos and the Seattle Seahawks on August 29, 2002, Ola Kimrin kicked a 65-yard field goal.[18] However, because pre-season games are not counted toward official records, this accomplishment is not the official record.

text: CFL[edit]

text:
62 yards, Paul McCallum, Saskatchewan Roughriders vs. Edmonton Eskimos, October 27, 2001[19]
60 yards, Dave Ridgway, Saskatchewan Roughriders vs. Winnipeg Blue Bombers, September 6, 1987[19]

text: College football[edit]

text:
69 yards, Ove Johansson, Abilene Christian vs. East Texas State on October 16, 1976. (NAIA)
67 yards, Tom Odle, Fort Hays State vs. Washburn, 1988. (NCAA)
67 yards, Joe Williams, Wichita State vs. Southern Illinois, 1978. (NCAA Division I)
67 yards, Russell Erxleben, Texas vs. Rice, 1977. (NCAA Division I)
67 yards, Steve Little, Arkansas vs. Texas, 1977.[20] (NCAA Division I)
65 yards, J. T. Haxall, Princeton vs. Yale, 1882.

text: All of the above kicks were successful with the use of a kicking tee, which was banned by the NCAA after the 1988 season.

text: 65 yards, Martin Gramatica, Kansas State vs. Northern Illinois, 1998 - without a tee [21]

text: The longest known drop-kicked field goal in college football was a 62-yard kick from Pat O'Dea, an Australian kicker who played on the Wisconsin Badgers football team. O'Dea's kick took place in a blizzard against Northwestern on November 15, 1898.[22]

text: U Sports[edit]

text: The longest field goal in U Sports football history is 59 yards, by Niko Difonte of Calgary Dinos, playing against the UBC Thunderbirds on November 11, 2017. The field goal was the final and winning play of the 81st Hardy Cup.[23][24]

text: High school[edit]

text:
68 yards, Dirk Borgognone, Reno High School vs. Sparks High School (Nevada), September 27, 1985[25][26]
67 yards, Austin Rehkow, Central Valley High School (Spokane Valley, Washington) vs. Shadle Park High School (Spokane, Washington), October 18, 2012, game-tying FG with :02 left in 4th quarter (CV would go on to win 62-55). [27][28] (tied with two others)
62 yards, David Rosenbaum, Woodrow Wilson High School (Washington, D.C.) vs. Spingarn High School, October 3, 2003. While no records are kept, considered to be the longest extra point scored. Penalties due to excessive celebration, unsportsmanlike conduct, and taunting.[29]

text: Independent amateur[edit]

text: 68 yards, Fabrizio Scaccia, Treasure Coast Bobcats (FL), March 29, 2009[30] (world record for a kick without the aid of a tee, which was banned for field goal and extra point attempts in the NCAA in 1989)

text: Independent Women's Football League[edit]

text: 44 yards, Sarah Oliver, California Quake vs. New Mexico Menace, April 26, 2008.[31]

text: Longest missed field goal return records[edit]

text: NFL[edit]

text: Field goal returns are rare in the NFL, since an attempt with sufficient distance that misses the uprights will automatically be dead. Returns are possible when a field goal is short, but in that case returners will usually down the ball so as to scrimmage from the spot of the kick. Normally, a return will only be attempted when there is not enough time left in the half to run a play from scrimmage. Nevertheless, four field goals have been returned for at least 107 yards in the 21st century:

text:
Distance returned
Returner
Team
Opposing kicker
Opposing team
Distance attempted
Date
Location

109 yards[32]
Antonio Cromartie
San Diego Chargers
Ryan Longwell
Minnesota Vikings
58 yards
November 4, 2007
Metrodome

108 yards[33]
Devin Hester
Chicago Bears
Jay Feely
New York Giants
52 yards
November 12, 2006
Giants Stadium

108 yards[34]
Nathan Vasher
Chicago Bears
Joe Nedney
San Francisco 49ers
52 yards
November 13, 2005
Soldier Field

107 yards[35]
Chris McAlister
Baltimore Ravens
Jason Elam
Denver Broncos
57 yards
September 30, 2002
Ravens Stadium

text: CFL[edit]

text: Because the goalposts in Canadian football are on the goal line, and because downing the ball in the end zone results in the kicking team scoring a single point, field goal returns are much more common. The longest missed field goal return in the CFL is 131 total yards. Against the Montreal Alouettes on August 22, 1958, the Toronto Argonauts' Boyd Carter ran 15 yards, then threw a lateral to Dave Mann, who then returned it for the final 116 yards.[36] This return, which started 21 yards behind the goal line, was during the era of 25-yard end zones (which made the maximum theoretical missed field return distance 134 yards in those days) and therefore cannot be met or exceeded on the modern field with 20-yard end zones. Since the shortening of the end zones in the CFL in 1986, a field goal has been returned for the maximum 129 yards on two occasions: by Tristan Jackson of the Saskatchewan Roughriders on July 14, 2012 [37] and by Trent Guy of the Montreal Alouettes on September 23, 2012.[38]

text: NCAA[edit]

text: In NCAA college football, only five missed field goals returns for touchdowns have ever been returned 100 yards or more:[39]

text:
September 17, 1966: Don Guest (California Golden Bears), 108-yard return for a touchdown after a failed 47-yard field goal attempt by Washington State.[39]
September 28, 1968: Richie Luzzi (Clemson Tigers), 108-yard return for a touchdown after a failed 47-yard field goal attempt by Georgia.[40]
September 7, 2013: Odell Beckham Jr. (LSU Tigers), 109-yard return for a touchdown after a failed 59-yard field goal attempt by UAB.[39]
November 30, 2013: Chris Davis, Jr. (Auburn Tigers), 109-yard return for a touchdown after what would have been a tie-breaking 57-yard field goal attempt by Alabama fell short as time expired, what some writers and fans call the greatest play in college football history.[41][42][43][44]
September 3, 2016: Brandon Wilson (Houston Cougars), 109-yard return for a touchdown after a failed 53-yard field goal attempt by Oklahoma.[45]

text: U Sports[edit]

text: In U Sports football, like in the CFL, the longest possible missed field goal return is 129 yards, and this has occurred three times.[24]

text:
Jeremy Botelho of the Manitoba Bisons playing against the Simon Fraser Clansmen on September 11, 2009
Jedd Gardner of the Guelph Gryphons playing against the McMaster Marauders on October 8, 2010
Tunde Adeleke of the Carleton Ravens playing against the Ottawa Gee-Gees on October 5, 2013


question_text: what did the court rule in tinker v. des moines

root

text: Background of the case[edit]

text: In 1965, Des Moines, Iowa residents John F. Tinker (15 years old), his siblings Mary Beth Tinker (13 years old), Hope Tinker (11 years old), and Paul Tinker (8 years old), along with their friend Christopher Eckhardt (16 years old) decided to wear black armbands to their schools (high school for John and Christopher, junior high for Mary Beth, elementary school for Hope and Paul) in protest of the Vietnam War and supporting the Christmas Truce called for by Senator Robert F. Kennedy. The principals of the Des Moines schools learned of the plan and met on December 14 to create a policy that stated that school children wearing an armband would be asked to remove it immediately. Students violating the policy would be suspended and allowed to return to school after agreeing to comply with it. The participants decided to violate this policy. Mary Beth Tinker and Christopher Eckhardt were suspended from school for wearing the armbands on December 16 and John Tinker was suspended for doing the same on the following day. (The two youngest participants were not punished.) Mary Beth, Christopher, and John were suspended from school until after January 1, 1966, when their protest had been scheduled to end.

tag: p

text: A suit was filed after the Iowa Civil Liberties Union approached the Tinker family and the ACLU agreed to help with the lawsuit. The children's fathers filed suit in U.S. District Court, which upheld the decision of the Des Moines school board. A tie vote in the U.S. Court of Appeals for the 8th Circuit meant that the U.S. District Court's decision continued to stand, and forced the Tinkers and Eckhardts to appeal to the Supreme Court directly. The case was argued before the court on November 12, 1968.

text: The case was funded by Des Moines residents Louise Noun, then the president of the Iowa Civil Liberties Union, and her brother, Joseph Rosenfield, a businessman.[1][2]

text: Legal precedents and issues[edit]

text: Previous decisions, such as West Virginia State Board of Education v. Barnette, had established that students did have some constitutional protections in public school. This case was the first time that the court set forth standards for safeguarding public school students' free speech rights.[3] This case involved symbolic speech, which was first recognized in Stromberg v. California.[3]

text: The Court's decision[edit]

text:
Wikisource has original text related to this article:
Tinker v. Des Moines Independent Community School District

tag: table

text: Majority opinion[edit]

text: The court's 7–2 decision held that the First Amendment applied to public schools, and that administrators would have to demonstrate constitutionally valid reasons for any specific regulation of speech in the classroom. The court observed, "It can hardly be argued that either students or teachers shed their constitutional rights to freedom of speech or expression at the schoolhouse gate."[4] Justice Abe Fortas wrote the majority opinion, holding that the speech regulation at issue in Tinker was "based upon an urgent wish to avoid the controversy which might result from the expression, even by the silent symbol of armbands, of opposition to this Nation's part in the conflagration in Vietnam." The Court held that for school officials to justify censoring speech, they "must be able to show that [their] action was caused by something more than a mere desire to avoid the discomfort and unpleasantness that always accompany an unpopular viewpoint," that the conduct that would "materially and substantially interfere with the requirements of appropriate discipline in the operation of the school."[5] The Court found that the actions of the Tinkers in wearing armbands did not cause disruption and held that their activity represented constitutionally protected symbolic speech.

text: Dissents[edit]

text: Justices Hugo Black and John M. Harlan II dissented. Black, who had long believed that disruptive "symbolic speech" was not constitutionally protected, wrote, "While I have always believed that under the First and Fourteenth Amendments neither the State nor the Federal Government has any authority to regulate or censor the content of speech, I have never believed that any person has a right to give speeches or engage in demonstrations where he pleases and when he pleases." Black argued that the Tinkers' behavior was indeed disruptive and declared, "I repeat that if the time has come when pupils of state-supported schools, kindergartens, grammar schools, or high schools, can defy and flout orders of school officials to keep their minds on their own schoolwork, it is the beginning of a new revolutionary era of permissiveness in this country fostered by the judiciary."[6]

text: Harlan dissented on the grounds that he "[found] nothing in this record which impugns the good faith of respondents in promulgating the armband regulation."[7]

text: Subsequent jurisprudence[edit]

text: Tinker remains a viable and frequently cited Court precedent, though subsequent Court decisions have determined limitations on the scope of student free speech rights. In Bethel School District v. Fraser, a 1986 case, the Supreme Court held that a high school student's sexual innuendo–laden speech during a student assembly was not constitutionally protected. Though Fraser applies the Tinker test of disruption to school decorum, if not undermining of educational mission, the effect is to make an exception to Tinker for "indecent" speech. Hazelwood v. Kuhlmeier, where the court ruled that schools have the right to regulate, for legitimate educational reasons, the content of non-forum, school-sponsored newspapers, also limits Tinker's application. The Court in Hazelwood clarified that both Fraser and Hazelwood were decided under the doctrine of Perry Education Association v. Perry Local Educators Association. Such a distinction keeps undisturbed the Material Disruption doctrine of Tinker, while deciding certain student free speech cases under the Nonpublic Forum doctrine of Perry. In Morse v. Frederick, the so-called "Bong Hits For Jesus" case of 2007, the Court held that schools may, consistent with the First Amendment, restrict student speech at a school-sponsored event, even those events occurring off school grounds, when that speech is reasonably viewed as promoting illegal drug use. In 2013, the full U.S. Court of Appeals for the Third Circuit re-heard a case en banc that had been argued before a panel of three of its judges, considering whether middle school students involved in a charitable effort—a breast cancer awareness drive—could be prohibited from wearing bracelets imprinted with "I ♥ Boobies! (Keep a Breast)".[8][9] The Third Circuit cited Tinker when ruling that the school's ban on the bracelets violated the students' right to free speech because the bracelets were not plainly offensive or disruptive and were speech conducted to raise awareness of a social issue.[10][11] The Supreme Court later declined to take up the case.[9]

text: Several cases have arisen from the modern display of the Confederate flag. Courts applying the "disruption" test under Tinker have held that schools may prohibit students from wearing clothing with Confederate symbols.[12]


document_title: RR Lyrae variable

question_text: who first used rr lyrae variable stars to determine distances in our milky way galaxy

text: RR Lyrae variable

text: Discovery and recognition[edit]

text: In surveys of globular clusters, these "cluster-type" variables were being rapidly identified in the mid-1890s, especially by E. C. Pickering.

text: Probably the first star of definitely RR Lyrae type found outside a cluster was U Leporis, discovered by J. Kapteyn in 1890.

text: The prototype star RR Lyrae was discovered prior to 1899 by Williamina Fleming, and reported by Pickering in 1900 as "indistinguishable from cluster-type variables".

text: From 1915 to the 1930s, the RR Lyraes became increasingly accepted as a class of star distinct from the classical Cepheids, due to their shorter periods, differing locations within the galaxy, and chemical differences. RR Lyrae variables are metal-poor, Population II stars.[1]

text: RR Lyraes have proven difficult to observe in external galaxies because of their intrinsic faintness. (In fact, Walter Baade's failure to find them in the Andromeda galaxy led him to suspect that the galaxy was much farther away than predicted, to reconsider the calibration of Cepheid variables, and to propose the concept of stellar populations.[1]) Using the Canada-France-Hawaii Telescope in the 1980s, Pritchet & van den Bergh found RR Lyraes in Andromeda's galactic halo[2] and, more recently, in its globular clusters.[3]

text: Classification[edit]

text: The RR Lyrae stars are conventionally divided into three main types,[1] following classification by S.I. Bailey based on the shape of the stars' brightness curves:

text:
RRab variables are the most common, making up 91% of all observed RR Lyrae, and display the steep rises in brightness typical of RR Lyrae
RRc are less common, making up 9% of observed RR Lyrae, and have shorter periods and more sinusoidal variation
RRd are rare, making up between <1% and 30%[4] of RR Lyrae in a system, and are double-mode pulsators, unlike RRab and RRc

tag: ul

text: Distribution[edit]

text: RR Lyrae stars were formerly called "cluster variables" because of their strong (but not exclusive) association with globular clusters; conversely, over 80% of all variables known in globular clusters are RR Lyraes.[5] RR Lyrae stars are found at all galactic latitudes, as opposed to classical Cepheids, which are strongly associated with the galactic plane.

text: Several times as many RR Lyraes are known as all Cepheids combined; in the 1980s, about 1900 were known in globular clusters. Some estimates have about 85000 in the Milky Way.[1]

text: Though binary star systems are common for typical stars, RR Lyrae are very rarely observed in pairs.[6]

text: Properties[edit]

text: RR Lyrae stars pulse in a manner similar to Cepheid variables, but the nature and histories of these stars is thought to be rather different. Like all variables on the Cepheid instability strip, pulsations are caused by the κ-mechanism, when the opacity of ionised helium varies with its temperature.

text: RR Lyraes are old, relatively low mass, Population II stars, in common with W Virginis and BL Herculis variables, the type II Cepheids. Classical Cepheid variables are higher mass population I stars. RR Lyrae variables are much more common than Cepheids, but also much less luminous. The average absolute magnitude of an RR Lyrae star is about +0.75, only 40 or 50 times brighter than our Sun.[7] Their period is shorter, typically less than one day, sometimes ranging down to seven hours. Some RRab stars, including RR Lyrae itself, exhibit the Blazhko effect in which there is a conspicuous phase and amplitude modulation.[8]

text: Period-luminosity relationships[edit]

text: Unlike Cepheid variables, RR Lyrae variables do not follow a strict period-luminosity relationship at visual wavelengths, although they do in the infrared K band.[9] They are normally analysed using a period-colour-relationship, for example using a Wesenheit function. In this way, they can be used as standard candles for distance measurements although there are difficulties with the effects of metallicity, faintness, and blending. The effect of blending can impact RR Lyrae variables sampled near the cores of globular clusters, which are so dense that in low-resolution observations multiple (unresolved) stars may appear as a single target. Thus the brightness measured for that seemingly single star (e.g., an RR Lyrae variable) is erroneously too bright, given those unresolved stars contributed to the brightness determined. Consequently, the computed distance is wrong, and certain researchers have argued that the blending effect can introduce a systematic uncertainty into the cosmic distance ladder, and may bias the estimated age of the Universe and the Hubble constant.[10][11][12]

text: Recent developments[edit]

text: The Hubble Space Telescope has identified several RR Lyrae candidates in globular clusters of the Andromeda galaxy[13] and has measured the distance to the prototype star RR Lyrae.[14]

text: The Kepler space telescope provided extended coverage of a single field with accurate photometric data. RR Lyrae itself was in Kepler field of view.[15]

text: The Gaia mission is expected to greatly improve knowledge of RR Lyraes by providing homogeneous spectrographic information of a large population of such stars.[16]


document_title: List of United States Representatives from Utah

question_text: who are utah's representatives in the house

question_tokens: who are utah 's representatives in the house

text: Current members[edit]

text: Updated November 2017.[1]

text:
Utah's 1st district: Rob Bishop (R) (since 2003)
Utah's 2nd district: Chris Stewart (R) (since 2013)
Utah's 3rd district: John Curtis (R) (since 2017)
Utah's 4th district: Mia Love (R) (since 2015)

text: List of representatives[edit]

text:
Representative
Years
Party
District
Notes

Allen, Clarence EmirClarence Emir Allen
000000001896-01-04-0000January 4, 1896 –
March 3, 1897
Republican
At-large
Utah achieved statehood.

Bernhisel, John M.John M. Bernhisel
000000001851-03-04-0000March 4, 1851 –
March 3, 1859
Independent
Territory
[Data unknown/missing.]

000000001861-03-04-0000March 4, 1861 –
March 3, 1863

Bishop, RobRob Bishop
000000002003-01-03-0000January 3, 2003 –
Present
Republican
1st
Incumbent

Bosone, Reva BeckReva Beck Bosone
000000001949-01-03-0000January 3, 1949 –
January 3, 1953
Democratic
2nd
[Data unknown/missing.]

Burton, Laurence J.Laurence J. Burton
000000001963-01-03-0000January 3, 1963 –
January 3, 1971
Republican
1st
[Data unknown/missing.]

Caine, John T.John T. Caine
000000001882-11-07-0000November 7, 1882 –
March 3, 1889
Democratic
Territory
First elected to finish Rep. George Q. Cannon's term.

000000001889-03-04-0000March 4, 1889 –
March 3, 1893
Populist

Cannon, ChrisChris Cannon
000000001997-01-03-0000January 3, 1997 –
January 3, 2009
Republican
3rd
[Data unknown/missing.]

Cannon, Frank J.Frank J. Cannon
000000001895-03-04-0000March 4, 1895 –
January 4, 1896
Republican
Territory
Utah Territory admitted as a state.

Cannon, George Q.George Q. Cannon
000000001873-03-04-0000March 4, 1873 –
April 20, 1882
Republican
Territory
Denied seat by the House after enactment of Edmunds Act.

Chaffetz, JasonJason Chaffetz
000000002009-01-03-0000January 3, 2009 –
June 30, 2017
Republican
3rd
[Data unknown/missing.]

Colton, Don B.Don B. Colton
000000001921-03-04-0000March 4, 1921 –
March 3, 1933
Republican
1st
[Data unknown/missing.]

Cook, MerrillMerrill Cook
000000001997-01-03-0000January 3, 1997 –
January 3, 2001
Republican
2nd
[Data unknown/missing.]

Curtis, JohnJohn Curtis
000000002017-11-07-0000November 7, 2017 –
Present
Republican
3rd
Elected to finish Jason Chaffetz's term.
Incumbent

Dawson, William A.William A. Dawson
000000001947-01-03-0000January 3, 1947 –
January 3, 1949
Republican
2nd
[Data unknown/missing.]

000000001953-01-03-0000January 3, 1953 –
January 3, 1959
[Data unknown/missing.]

Dixon, Henry AldousHenry Aldous Dixon
000000001955-01-03-0000January 3, 1955 –
January 3, 1961
Republican
1st
[Data unknown/missing.]

Granger, Walter K.Walter K. Granger
000000001941-01-03-0000January 3, 1941 –
January 3, 1953
Democratic
1st
[Data unknown/missing.]

Greene, EnidEnid Greene
000000001995-01-03-0000January 3, 1995 –
January 3, 1997
Republican
2nd
[Data unknown/missing.]

Hansen, James V.James V. Hansen
000000001981-01-03-0000January 3, 1981 –
January 3, 2003
Republican
1st
[Data unknown/missing.]

Hooper, William H.William H. Hooper
000000001859-03-04-0000March 4, 1859 –
March 3, 1861
Democratic
Territory
[Data unknown/missing.]

000000001865-03-04-0000March 4, 1865 –
March 3, 1873

Howe, Allan TurnerAllan Turner Howe
000000001975-01-03-0000January 3, 1975 –
January 3, 1977
Democratic
2nd
[Data unknown/missing.]

Howell, JosephJoseph Howell
000000001903-03-04-0000March 4, 1903 –
March 3, 1913
Republican
At-large
[Data unknown/missing.]

000000001913-03-04-0000March 4, 1913 –
March 3, 1917
1st

Johnson, JacobJacob Johnson
000000001913-03-04-0000March 4, 1913 –
March 3, 1915
Republican
2nd
[Data unknown/missing.]

King, David S.David S. King
000000001959-01-03-0000January 3, 1959 –
January 3, 1963
Democratic
2nd
[Data unknown/missing.]

000000001965-01-03-0000January 3, 1965 –
January 3, 1967

King, William H.William H. King
000000001900-04-02-0000April 2, 1900 –
March 3, 1901
Democratic
At-large
Won special election after Rep-elect B. H. Roberts was denied seat.

Kinney, John F.John F. Kinney
000000001863-03-04-0000March 4, 1863 –
March 3, 1865
Democratic
Territory
[Data unknown/missing.]

Leatherwood, Elmer O.Elmer O. Leatherwood
000000001921-03-04-0000March 4, 1921 –
December 24, 1929
Republican
2nd
Died.

Lloyd, Sherman P.Sherman P. Lloyd
000000001963-01-03-0000January 3, 1963 –
January 3, 1965
Republican
2nd
[Data unknown/missing.]

000000001967-01-03-0000January 3, 1967 –
January 3, 1973

Loofbourow, Frederick C.Frederick C. Loofbourow
000000001930-11-04-0000November 4, 1930 –
March 3, 1933
Republican
2nd
Elected to finish Elmer O. Leatherwood's term.

Love, MiaMia Love
000000002015-01-03-0000January 3, 2015 –
Present
Republican
4th
Incumbent

Marriott, David DanielDavid Daniel Marriott
000000001977-01-03-0000January 3, 1977 –
January 3, 1985
Republican
2nd
[Data unknown/missing.]

Matheson, JimJim Matheson
000000002001-01-03-0000January 3, 2001 –
January 3, 2013
Democratic
2nd
[Data unknown/missing.]

000000002013-01-03-0000January 3, 2013 –
January 3, 2015
4th

Mays, James HenryJames Henry Mays
000000001915-03-04-0000March 4, 1915 –
March 3, 1921
Democratic
2nd
[Data unknown/missing.]

McKay, K. GunnK. Gunn McKay
000000001971-01-03-0000January 3, 1971 –
January 3, 1981
Democratic
1st
[Data unknown/missing.]

Monson, David SmithDavid Smith Monson
000000001985-01-03-0000January 3, 1985 –
January 3, 1987
Republican
2nd
[Data unknown/missing.]

Murdock, AbeAbe Murdock
000000001933-03-04-0000March 4, 1933 –
January 3, 1941
Democratic
1st
[Data unknown/missing.]

Nielson, Howard C.Howard C. Nielson
000000001983-01-03-0000January 3, 1983 –
January 3, 1991
Republican
3rd
[Data unknown/missing.]

Orton, BillBill Orton
000000001991-01-03-0000January 3, 1991 –
January 3, 1997
Democratic
3rd
[Data unknown/missing.]

Owens, WayneWayne Owens
000000001973-01-03-0000January 3, 1973 –
January 3, 1975
Democratic
2nd
[Data unknown/missing.]

000000001987-01-03-0000January 3, 1987 –
January 3, 1993

Peterson, M. BlaineM. Blaine Peterson
000000001961-01-03-0000January 3, 1961 –
January 3, 1963
Democratic
1st
[Data unknown/missing.]

Rawlins, Joseph L.Joseph L. Rawlins
000000001893-03-04-0000March 4, 1893 –
March 3, 1895
Democratic
Territory
[Data unknown/missing.]

Robinson, J. W.J. W. Robinson
000000001933-03-03-0000March 3, 1933 –
January 3, 1947
Democratic
2nd
[Data unknown/missing.]

Shepherd, KarenKaren Shepherd
000000001993-01-03-0000January 3, 1993 –
January 3, 1995
Democratic
2nd
[Data unknown/missing.]

Stewart, ChrisChris Stewart
000000002013-01-03-0000January 3, 2013 –
Present
Republican
2nd
Incumbent

Stringfellow, Douglas R.Douglas R. Stringfellow
000000001953-01-03-0000January 3, 1953 –
January 3, 1955
Republican
1st
[Data unknown/missing.]

Sutherland, GeorgeGeorge Sutherland
000000001901-03-04-0000March 4, 1901 –
March 3, 1903
Republican
At-large
[Data unknown/missing.]

Welling, Milton H.Milton H. Welling
000000001917-03-04-0000March 4, 1917 –
March 3, 1921
Democratic
1st
[Data unknown/missing.]

text: Living former Members of the U.S. House of Representatives from Utah[edit]

text: As of July 2017[update], there are nine former members of the U.S. House of Representatives from U.S. State of Utah who are currently living at this time. The most recent representative to die was David S. King (1959–1963, 1965–1967) on May 5, 2009. The most recently serving representative to die was Bill Orton (1991–1997) on April 18, 2009.

text:
Representative
Term of office
District
Date of birth (and age)

David Daniel Marriott
1977–1985
2nd
(1939-11-02) November 2, 1939 (age 78)

James V. Hansen
1981–2003
1st
(1932-08-14) August 14, 1932 (age 85)

Howard C. Nielson
1983–1991
3rd
(1924-09-12) September 12, 1924 (age 93)

David S. Monson
1985–1987
2nd
(1945-06-20) June 20, 1945 (age 72)

Karen Shepherd
1993–1995
2nd
(1940-07-05) July 5, 1940 (age 77)

Enid Greene
1995–1997
2nd
(1958-06-05) June 5, 1958 (age 59)

Chris Cannon
1997–2009
3rd
(1950-10-20) October 20, 1950 (age 67)

Jim Matheson
2001–2015
2nd (2001–2013)
4th (2013–2015)
(1960-03-21) March 21, 1960 (age 57)

Jason Chaffetz
2009–2017
3rd
(1967-03-26) March 26, 1967 (age 50)


document_title: Moss

question_text: moss growing on trees is an example of what

text: Moss

text: Physical characteristics

text: Description

text: Botanically, mosses are non-vascular plants in the land plant division Bryophyta. They are small (a few centimeters tall) herbaceous (non-woody) plants that absorb water and nutrients mainly through their leaves and harvest carbon dioxide and sunlight to create food by photosynthesis.[5][6] They differ from vascular plants in lacking water-bearing xylem tracheids or vessels. As in liverworts and hornworts, the haploid gametophyte generation is the dominant phase of the life cycle. This contrasts with the pattern in all vascular plants (seed plants and pteridophytes), where the diploid sporophyte generation is dominant. Mosses reproduce using spores, not seeds, and have no flowers.

text: Moss gametophytes have stems which may be simple or branched and upright or prostrate. Their leaves are simple, usually only a single layer of cells with no internal air spaces, often with thicker midribs. They do not have proper roots, but have threadlike rhizoids that anchor them to their substrate. Mosses do not absorb water or nutrients from their substrate through their rhizoids. They can be distinguished from liverworts (Marchantiophyta or Hepaticae) by their multi-cellular rhizoids. Spore-bearing capsules or sporangia of mosses are borne singly on long, unbranched stems, thereby distinguishing them from the polysporangiophytes, which include all vascular plants. The spore-bearing sporophytes (i.e. the diploid multicellular generation) are short-lived and dependent on the gametophyte for water supply and nutrition. Also, in most mosses, the spore-bearing capsule enlarges and matures after its stalk elongates, while in liverworts the capsule enlarges and matures before its stalk elongates.[6] Other differences are not universal for all mosses and all liverworts, but the presence of clearly differentiated stem with simple-shaped, ribbed leaves, without deeply lobed or segmented leaves and not arranged in three ranks, all point to the plant being a moss.

text: Life cycle

text: Vascular plants have two sets of chromosomes in their vegetative cells and are said to be diploid, i.e. each chromosome has a partner that contains the same, or similar, genetic information. By contrast, mosses and other bryophytes have only a single set of chromosomes and so are haploid (i.e. each chromosome exists in a unique copy within the cell). There is a period in the moss life cycle when they do have a double set of paired chromosomes, but this happens only during the sporophyte stage.

text: The moss life-cycle starts with a haploid spore that germinates to produce a protonema (pl. protonemata), which is either a mass of thread-like filaments or thalloid (flat and thallus-like). Massed moss protonemata typically look like a thin green felt, and may grow on damp soil, tree bark, rocks, concrete, or almost any other reasonably stable surface. This is a transitory stage in the life of a moss, but from the protonema grows the gametophore ("gamete-bearer") that is structurally differentiated into stems and leaves. A single mat of protonemata may develop several gametophore shoots, resulting in a clump of moss.

text: From the tips of the gametophore stems or branches develop the sex organs of the mosses. The female organs are known as archegonia (sing. archegonium) and are protected by a group of modified leaves known as the perichaetum (plural, perichaeta). The archegonia are small flask-shaped clumps of cells with an open neck (venter) down which the male sperm swim. The male organs are known as antheridia (sing. antheridium) and are enclosed by modified leaves called the perigonium (pl. perigonia). The surrounding leaves in some mosses form a splash cup, allowing the sperm contained in the cup to be splashed to neighboring stalks by falling water droplets.

text: Mosses can be either dioicous (compare dioecious in seed plants) or monoicous (compare monoecious). In dioicous mosses, male and female sex organs are borne on different gametophyte plants. In monoicous (also called autoicous) mosses, both are borne on the same plant. In the presence of water, sperm from the antheridia swim to the archegonia and fertilisation occurs, leading to the production of a diploid sporophyte. The sperm of mosses is biflagellate, i.e. they have two flagellae that aid in propulsion. Since the sperm must swim to the archegonium, fertilisation cannot occur without water. Some species (for example Mnium hornum or several species of Polytrichum) keep their antheridia in so called 'splash cups', bowl-like structures on the shoot tips that propel the sperm several decimeters when water droplets hit it, increasing the fertilization distance.[7]

text: After fertilisation, the immature sporophyte pushes its way out of the archegonial venter. It takes about a quarter to half a year for the sporophyte to mature. The sporophyte body comprises a long stalk, called a seta, and a capsule capped by a cap called the operculum. The capsule and operculum are in turn sheathed by a haploid calyptra which is the remains of the archegonial venter. The calyptra usually falls off when the capsule is mature. Within the capsule, spore-producing cells undergo meiosis to form haploid spores, upon which the cycle can start again. The mouth of the capsule is usually ringed by a set of teeth called peristome. This may be absent in some mosses.

text: Most mosses rely on the wind to disperse the spores. In the genus Sphagnum the spores are projected about 10–20 cm (4–8 in) off the ground by compressed air contained in the capsules; the spores are accelerated to about 36,000 times the earth's gravitational acceleration g.[8][9]

text: It has recently been found that microarthropods, such as springtails and mites, can effect moss fertilization[10] and that this process is mediated by moss-emitted scents. Male and female fire moss, for example emit different and complex volatile organic scents.[11] Female plants emit more compounds than male plants. Springtails were found to choose female plants preferentially, and one study found that springtails enhance moss fertilization, suggesting a scent-mediated relationship analogous to the plant-pollinator relationship found in many seed plants.[11] The stinkmoss species Splachnum sphaericum develops insect pollination further by attracting flies to its sporangia with a strong smell of carrion, and providing a strong visual cue in the form of red-coloured swollen collars beneath each spore capsule. Flies attracted to the moss carry its spores to fresh herbivore dung, which is the favoured habitat of the species of this genus.[12]

text: In many mosses, e.g. Ulota phyllantha, green vegetative structures called gemmae are produced on leaves or branches, which can break off and form new plants without the need to go through the cycle of fertilization. This is a means of asexual reproduction, and the genetically identical units can lead to the formation of clonal populations.

text: Dwarf males

text: Moss dwarf males (also known as nannandry or phyllodioicy) originate from wind-dispersed male spores that settle and germinate on the female shoot where their growth is restricted to a few millimeters. In some species, dwarfness is genetically determined, in that all male spores become dwarf.[13] More often, however, it is environmentally determined in that male spores that land on a female become dwarf, while those that land elsewhere develop into large, female-sized males.[13][14][15][16] In the latter case, dwarf males that are transplanted from females to another substrate develop into large shoots, suggesting that the females emit a substance which inhibits the growth of germinating males and possibly also quickens their onset of sexual maturation.[15][16] The nature of such a substance is unknown, but the phytohormone auxin may be involved[13]

text: Having the males growing as dwarfs on the female is expected to increase the fertilization efficiency by minimizing the distance between male and female reproductive organs. Accordingly, it has been observed that fertilization frequency is positively associated with the presence of dwarf males in several phyllodioicous species.[17][18]

text: Dwarf males occur in several unrelated lineages[18][19] and is showing to be more common than previously thought.[18] For example, it is estimated that between one quarter and half of all dioicous pleurocarps have dwarf males.[18]

text: DNA repair

text: The moss Phycomitrella patens has been used as a model organism to study how plants repair damage to their DNA, especially the repair mechanism known as homologous recombination. If the plant cannot repair DNA damage, e.g. double-strand breaks, in their somatic cells, the cells can lose normal functions or die. If this occurs during meiosis (part of sexual reproduction), they could become infertile. The genome of P. patens has been sequenced, which has allowed several genes involved in DNA repair to be identified.[20] P. patens mutants that are defective in key steps of homologous recombination have been used to work out how the repair mechanism functions in plants. For example, a study of P. patens mutants defective in RpRAD51, a gene that encodes a protein at the core of the recombinational repair reaction, indicated that homologous recombination is essential for repairing DNA double-strand breaks in this plant.[21] Similarly, studies of mutants defective in Ppmre11 or Pprad50 (that encode key proteins of the MRN complex, the principal sensor of DNA double-strand breaks) showed that these genes are necessary for repair of DNA damage as well as for normal growth and development.[22]

text: Classification

text: Traditionally, mosses were grouped with the liverworts and hornworts in the division Bryophyta (bryophytes, or Bryophyta sensu lato), within which the mosses made up the class Musci. However, this definition of Bryophyta was paraphyletic, as the mosses appear to be more closely related to vascular plants than to liverworts. Bryophytes are now split among three divisions: Bryophyta, Marchantiophyta and Anthocerotophyta. The current circumscription of Bryophyta includes only the mosses.

text: The mosses, now division Bryophyta (Bryophyta sensu stricto), are divided into eight classes:

text:
division Bryophyta

class Takakiopsida
class Sphagnopsida
class Andreaeopsida
class Andreaeobryopsida
class Oedipodiopsida
class Polytrichopsida
class Tetraphidopsida
class Bryopsida

liverworts

hornworts

vascular plants

Bryophyta

Takakiopsida

Sphagnopsida

Andreaeopsida

Andreaeobryopsida

Neomusci

Oedipodiopsida

Cenomusci

Polytrichopsida

Altamusci

Tetraphidopsida

Bryopsida

The current phylogeny and composition of the Bryophyta.[2][23]

text: Six of the eight classes contain only one or two genera each. Polytrichopsida includes 23 genera, and Bryopsida includes the majority of moss diversity with over 95% of moss species belonging to this class.

text: The Sphagnopsida, the peat-mosses, comprise the two living genera Ambuchanania and Sphagnum, as well as fossil taxa. However, the genus Sphagnum is a diverse, widespread, and economically important one. These large mosses form extensive acidic bogs in peat swamps. The leaves of Sphagnum have large dead cells alternating with living photosynthetic cells. The dead cells help to store water. Aside from this character, the unique branching, thallose (flat and expanded) protonema, and explosively rupturing sporangium place it apart from other mosses.

text: Andreaeopsida and Andreaeobryopsida are distinguished by the biseriate (two rows of cells) rhizoids, multiseriate (many rows of cells) protonema, and sporangium that splits along longitudinal lines. Most mosses have capsules that open at the top.

text: Polytrichopsida have leaves with sets of parallel lamellae, flaps of chloroplast-containing cells that look like the fins on a heat sink. These carry out photosynthesis and may help to conserve moisture by partially enclosing the gas exchange surfaces. The Polytrichopsida differ from other mosses in other details of their development and anatomy too, and can also become larger than most other mosses, with e.g. Polytrichum commune forming cushions up to 40 cm (16 in) high. The tallest land moss, a member of the Polytrichidae is probably Dawsonia superba, a native to New Zealand and other parts of Australasia.

text: Geological history

text: The fossil record of moss is sparse, due to their soft-walled and fragile nature. Unambiguous moss fossils have been recovered from as early as the Permian of Antarctica and Russia, and a case is put forwards for Carboniferous mosses.[24] It has further been claimed that tube-like fossils from the Silurian are the macerated remains of moss calyptræ.[25] Mosses also appear to evolve 2–3 times slower than ferns, gymnosperms and angiosperms.[26]

text: Recent research show that ancient moss could explain why the Ordovician ice ages occurred. When the ancestors of today's moss started to spread on land 470 million years ago, they absorbed CO2 from the atmosphere and extracted minerals by secreting organic acids that dissolved the rocks they were growing on. These chemically altered rocks in turn reacted with the atmospheric CO2 and formed new carbonate rocks in the ocean through the weathering of calcium and magnesium ions from silicate rocks. The weathered rocks also released a lot of phosphorus and iron which ended up in the oceans, where it caused massive algal blooms, resulting in organic carbon burial, extracting more carbon dioxide from the atmosphere. Small organisms feeding on the nutrients created large areas without oxygen, which caused a mass extinction of marine species, while the levels of CO2 dropped all over the world, allowing the formation of ice caps on the poles.[27][28]

text: Ecology

text: Habitat

text: Since moss gametophytes are autotrophic they require enough sunlight to perform photosynthesis.[29] Shade tolerance varies by species, just as it does with higher plants. In most areas, mosses grow chiefly in areas of dampness and shade, such as wooded areas and at the edges of streams; but they can grow anywhere in cool damp cloudy climates, and some species are adapted to sunny, seasonally dry areas like alpine rocks or stabilized sand dunes.

text: Choice of substrate varies by species as well. Moss species can be classed as growing on: rocks, exposed mineral soil, disturbed soils, acid soil, calcareous soil, cliff seeps and waterfall spray areas, streamsides, shaded humusy soil, downed logs, burnt stumps, tree trunk bases, upper tree trunks, and tree branches or in bogs. Moss species growing on or under trees are often specific about the species of trees they grow on, such as preferring conifers to broadleaf trees, oaks to alders, or vice versa.[6] While mosses often grow on trees as epiphytes, they are never parasitic on the tree.

text: Mosses are also found in cracks between paving stones in damp city streets, and on roofs. Some species adapted to disturbed, sunny areas are well adapted to urban conditions and are commonly found in cities. Examples would be Rhytidiadelphus squarrosus, a garden weed in Vancouver and Seattle areas; Bryum argenteum, the cosmopolitan sidewalk moss, and Ceratodon purpureus, red roof moss, another cosmopolitan species. A few species are wholly aquatic, such as Fontinalis antipyretica, common water moss; and others such as Sphagnum inhabit bogs, marshes and very slow-moving waterways.[6] Such aquatic or semi-aquatic mosses can greatly exceed the normal range of lengths seen in terrestrial mosses. Individual plants 20–30 cm (8–12 in) or more long are common in Sphagnum species for example.

text: Wherever they occur, mosses require liquid water for at least part of the year to complete fertilisation. Many mosses can survive desiccation, sometimes for months, returning to life within a few hours of rehydration.[29]

text: It is generally believed that in northern latitudes, the north side of trees and rocks will generally have more luxuriant moss growth on average than other sides.[30] This is assumed to be because the sun on the south side creates a dry environment. South of the equator the reverse would be true. However, naturalists feel that mosses grow on the damper side of trees and rocks.[5] In some cases, such as sunny climates in temperate northern latitudes, this will be the shaded north side of the tree or rock. On steep slopes it may be the uphill side. For mosses that grow on tree branches, this is generally the upper side of the branch on horizontally growing sections or near the crotch. In cool damp cloudy climates, all sides of tree trunks and rocks may be equally damp enough for mosses. And different species of mosses have different moisture and sun requirements so will grow on different sections of the same tree or rock.

text: Moss-cyanobacteria relationship

text: In boreal forests, some species of moss play an important role in providing nitrogen for the ecosystem due to their relationship with nitrogen-fixing cyanobacteria. Cyanobacteria colonizes moss and receives shelter in return for providing fixed nitrogen. Moss releases the fixed nitrogen, along with other nutrients, into the soil "upon disturbances like drying-rewetting and fire events," making it available throughout the ecosystem.[31]

text: Cultivation

text: Moss is often considered a weed in grass lawns, but is deliberately encouraged to grow under aesthetic principles exemplified by Japanese gardening. In old temple gardens, moss can carpet a forest scene. Moss is thought to add a sense of calm, age, and stillness to a garden scene. Moss is also used in bonsai to cover the soil and enhance the impression of age.[32] Rules of cultivation are not widely established. Moss collections are quite often begun using samples transplanted from the wild in a water-retaining bag. However, specific species of moss can be extremely difficult to maintain away from their natural sites with their unique requirements of combinations of light, humidity, substrate chemistry, shelter from wind, etc.

text: Growing moss from spores is even less controlled. Moss spores fall in a constant rain on exposed surfaces; those surfaces which are hospitable to a certain species of moss will typically be colonised by that moss within a few years of exposure to wind and rain. Materials which are porous and moisture retentive, such as brick, wood, and certain coarse concrete mixtures are hospitable to moss. Surfaces can also be prepared with acidic substances, including buttermilk, yogurt, urine, and gently puréed mixtures of moss samples, water and ericaceous compost.

text: In the cool cloudy damp Pacific Northwest, moss is sometimes allowed to grow naturally as a lawn substitute, one that needs little or no mowing, fertilizing or watering. In this case, grass is considered to be the weed.[33] Landscapers in the Seattle area sometimes collect boulders and downed logs growing mosses for installation in gardens and landscapes. Woodland gardens in many parts of the world can include a carpet of natural mosses.[29] The Bloedel Reserve on Bainbridge Island, Washington State, is famous for its moss garden. The moss garden was created by removing shrubby underbrush and herbaceous groundcovers, thinning trees, and allowing mosses to fill in naturally.[34]

text: Mosses are sometimes used in green roofs. Advantages of mosses over higher plants in green roofs include reduced weight loads, increased water absorption, no fertilizer requirements, and high drought tolerance. Since mosses do not have true roots, they require less planting medium than higher plants with extensive root systems. With proper species selection for the local climate, mosses in green roofs require no irrigation once established and are low maintenance.[35]

text: Inhibiting moss growth

text: Moss can be a troublesome weed in containerized nursery operations and greenhouses.[36] Vigorous moss growth can inhibit seedling emergence and penetration of water and fertilizer to the plant roots.

text: Moss growth can be inhibited by a number of methods:

text:
Decreasing availability of water through drainage.
Increasing direct sunlight.
Increasing number and resources available for competitive plants like grasses.
Increasing the soil pH with the application of lime.
Heavy traffic or manually disturbing the moss bed with a rake
Application of chemicals such as ferrous sulfate (e.g. in lawns) or bleach (e.g. on solid surfaces).
In containerized nursery operations, coarse mineral materials such as sand, gravel, and rock chips are used as a fast-draining top dressing in plant containers to discourage moss growth.

text: The application of products containing ferrous sulfate or ferrous ammonium sulfate will kill moss; these ingredients are typically in commercial moss control products and fertilizers. Sulfur and Iron are essential nutrients for some competing plants like grasses. Killing moss will not prevent regrowth unless conditions favorable to their growth are changed.[37]

text: Mossery

text: A passing fad for moss-collecting in the late 19th century led to the establishment of mosseries in many British and American gardens. The mossery is typically constructed out of slatted wood, with a flat roof, open to the north side (maintaining shade). Samples of moss were installed in the cracks between wood slats. The whole mossery would then be regularly moistened to maintain growth.

text: Uses

text: Traditional

text: Preindustrial societies made use of the mosses growing in their areas.

text: Laplanders, North American tribes, and other circumpolar people used mosses for bedding.[5][29] Mosses have also been used as insulation both for dwellings and in clothing. Traditionally, dried moss was used in some Nordic countries and Russia as an insulator between logs in log cabins, and tribes of the northeastern United States and southeastern Canada used moss to fill chinks in wooden longhouses.[29] Circumpolar and alpine peoples have used mosses for insulation in boots and mittens. Ötzi the Iceman had moss-packed boots.[29]

text: The capacity dried mosses have to absorb fluids, has made their use practical in both medical and culinary uses. North American tribal people used mosses for diapers, wound dressing, and menstrual fluid absorption.[29] Tribes of the Pacific Northwest in the United States and Canada used mosses to clean salmon prior to drying, and packed wet moss into pit ovens for steaming camas bulbs. Food storage baskets and boiling baskets were also packed with mosses.[29]

text: Commercial

text: There is a substantial market in mosses gathered from the wild. The uses for intact moss are principally in the florist trade and for home decoration. Decaying moss in the genus Sphagnum is also the major component of peat, which is "mined" for use as a fuel, as a horticultural soil additive, and in smoking malt in the production of Scotch whisky.

text: Sphagnum moss, generally the species cristatum and subnitens, is harvested while still growing and is dried out to be used in nurseries and horticulture as a plant growing medium. The practice of harvesting peat moss should not be confused with the harvesting of moss peat. Peat moss can be harvested on a sustainable basis and managed so that regrowth is allowed, whereas the harvesting of moss peat is generally considered to cause significant environmental damage as the peat is stripped with little or no chance of recovery.[citation needed]

text: Some sphagnum mosses can absorb up to 20 times their own weight in water.[38] In World War I, Sphagnum mosses were used as first-aid dressings on soldiers' wounds, as these mosses said to absorb liquids three times faster than cotton, retain liquids better, better distribute liquids uniformly throughout themselves, and are cooler, softer, and be less irritating.[38] It is also claimed to have antibacterial properties.[39] Native Americans were one of the peoples to use Sphagnum for diapers and napkins, which is still done in Canada.[40]

text: In rural UK, Fontinalis antipyretica was traditionally used to extinguish fires as it could be found in substantial quantities in slow-moving rivers and the moss retained large volumes of water which helped extinguish the flames. This historical use is reflected in its specific Latin/Greek name, the approximate meaning of which is "against fire".

text: In Finland, peat mosses have been used to make bread during famines.[41] In Mexico, Moss is used as a Christmas decoration.

text: Physcomitrella patens is increasingly used in biotechnology. Prominent examples are the identification of moss genes with implications for crop improvement or human health[42] and the safe production of complex biopharmaceuticals in the moss bioreactor, developed by Ralf Reski and his co-workers.[43]


document_title: Absolute zero

question_text: 0 k is equal to what temperature in celsius

text: Absolute zero

text: Thermodynamics near absolute zero[edit]

text: At temperatures near 0 K (−273.15 °C; −459.67 °F), nearly all molecular motion ceases and ΔS = 0 for any adiabatic process, where S is the entropy. In such a circumstance, pure substances can (ideally) form perfect crystals as T → 0. Max Planck's strong form of the third law of thermodynamics states the entropy of a perfect crystal vanishes at absolute zero. The original Nernst heat theorem makes the weaker and less controversial claim that the entropy change for any isothermal process approaches zero as T → 0:

text: The implication is that the entropy of a perfect crystal simply approaches a constant value.

text: The Nernst postulate identifies the isotherm T = 0 as coincident with the adiabat S = 0, although other isotherms and adiabats are distinct. As no two adiabats intersect, no other adiabat can intersect the T = 0 isotherm. Consequently no adiabatic process initiated at nonzero temperature can lead to zero temperature. (≈ Callen, pp. 189–190)

text: A perfect crystal is one in which the internal lattice structure extends uninterrupted in all directions. The perfect order can be represented by translational symmetry along three (not usually orthogonal) axes. Every lattice element of the structure is in its proper place, whether it is a single atom or a molecular grouping. For substances that exist in two (or more) stable crystalline forms, such as diamond and graphite for carbon, there is a kind of chemical degeneracy. The question remains whether both can have zero entropy at T = 0 even though each is perfectly ordered.

text: Perfect crystals never occur in practice; imperfections, and even entire amorphous material inclusions, can and do simply get "frozen in" at low temperatures, so transitions to more stable states do not occur.

text: Using the Debye model, the specific heat and entropy of a pure crystal are proportional to T 3, while the enthalpy and chemical potential are proportional to T 4. (Guggenheim, p. 111) These quantities drop toward their T = 0 limiting values and approach with zero slopes. For the specific heats at least, the limiting value itself is definitely zero, as borne out by experiments to below 10 K. Even the less detailed Einstein model shows this curious drop in specific heats. In fact, all specific heats vanish at absolute zero, not just those of crystals. Likewise for the coefficient of thermal expansion. Maxwell's relations show that various other quantities also vanish. These phenomena were unanticipated.

text: Since the relation between changes in Gibbs free energy (G), the enthalpy (H) and the entropy is

text: thus, as T decreases, ΔG and ΔH approach each other (so long as ΔS is bounded). Experimentally, it is found that all spontaneous processes (including chemical reactions) result in a decrease in G as they proceed toward equilibrium. If ΔS and/or T are small, the condition ΔG < 0 may imply that ΔH < 0, which would indicate an exothermic reaction. However, this is not required; endothermic reactions can proceed spontaneously if the TΔS term is large enough.

text: Moreover, the slopes of the derivatives of ΔG and ΔH converge and are equal to zero at T = 0. This ensures that ΔG and ΔH are nearly the same over a considerable range of temperatures and justifies the approximate empirical Principle of Thomsen and Berthelot, which states that the equilibrium state to which a system proceeds is the one that evolves the greatest amount of heat, i.e., an actual process is the most exothermic one. (Callen, pp. 186–187)

text: One model that estimates the properties of an electron gas at absolute zero in metals is the Fermi gas. The electrons, being Fermions, must be in different quantum states, which leads the electrons to get very high typical velocities, even at absolute zero. The maximum energy that electrons can have at absolute zero is called the Fermi energy. The Fermi temperature is defined as this maximum energy divided by Boltzmann's constant, and is of the order of 80,000 K for typical electron densities found in metals. For temperatures significantly below the Fermi temperature, the electrons behave in almost the same way as at absolute zero. This explains the failure of the classical equipartition theorem for metals that eluded classical physicists in the late 19th century.

text: Relation with Bose–Einstein condensate[edit]

text: A Bose–Einstein condensate (BEC) is a state of matter of a dilute gas of weakly interacting bosons confined in an external potential and cooled to temperatures very near absolute zero. Under such conditions, a large fraction of the bosons occupy the lowest quantum state of the external potential, at which point quantum effects become apparent on a macroscopic scale.[5]

text: This state of matter was first predicted by Satyendra Nath Bose and Albert Einstein in 1924–25. Bose first sent a paper to Einstein on the quantum statistics of light quanta (now called photons). Einstein was impressed, translated the paper from English to German and submitted it for Bose to the Zeitschrift für Physik, which published it. Einstein then extended Bose's ideas to material particles (or matter) in two other papers.[6]

text: Seventy years later, in 1995, the first gaseous condensate was produced by Eric Cornell and Carl Wieman at the University of Colorado at Boulder NIST-JILA lab, using a gas of rubidium atoms cooled to 170 nanokelvins (nK)[7] (6993170000000000000♠1.7×10−7 K).[8]

text: A record cold temperature of 450 ±80 picokelvins (pK) (6990450000000000000♠4.5×10−10 K) in a Bose–Einstein condensate (BEC) of sodium atoms was achieved in 2003 by researchers at MIT.[9] The associated black-body (peak emittance) wavelength of 6,400 kilometers is roughly the radius of Earth.

text: Absolute temperature scales[edit]

text: Absolute, or thermodynamic, temperature is conventionally measured in kelvins (Celsius-scaled increments) and in the Rankine scale (Fahrenheit-scaled increments) with increasing rarity. Absolute temperature measurement is uniquely determined by a multiplicative constant which specifies the size of the degree, so the ratios of two absolute temperatures, T2/T1, are the same in all scales. The most transparent definition of this standard comes from the Maxwell–Boltzmann distribution. It can also be found in Fermi–Dirac statistics (for particles of half-integer spin) and Bose–Einstein statistics (for particles of integer spin). All of these define the relative numbers of particles in a system as decreasing exponential functions of energy (at the particle level) over kT, with k representing the Boltzmann constant and T representing the temperature observed at the macroscopic level.[1]

text: Negative temperatures[edit]

text: Temperatures that are expressed as negative numbers on the familiar Celsius or Fahrenheit scales are simply colder than the zero points of those scales. Certain systems can achieve truly negative temperatures; that is, their thermodynamic temperature (expressed in kelvins) can be of a negative quantity. A system with a truly negative temperature is not colder than absolute zero. Rather, a system with a negative temperature is hotter than any system with a positive temperature, in the sense that if a negative-temperature system and a positive-temperature system come in contact, heat flows from the negative to the positive-temperature system.[10]

text: Most familiar systems cannot achieve negative temperatures because adding energy always increases their entropy. However, some systems have a maximum amount of energy that they can hold, and as they approach that maximum energy their entropy actually begins to decrease. Because temperature is defined by the relationship between energy and entropy, such a system's temperature becomes negative, even though energy is being added.[10] As a result, the Boltzmann factor for states of systems at negative temperature increases rather than decreases with increasing state energy. Therefore, no complete system, i.e. including the electromagnetic modes, can have negative temperatures, since there is no highest energy state,[citation needed] so that the sum of the probabilities of the states would diverge for negative temperatures. However, for quasi-equilibrium systems (e.g. spins out of equilibrium with the electromagnetic field) this argument does not apply, and negative effective temperatures are attainable.

text: On 3 January 2013, physicists announced that they had created a quantum gas made up of potassium atoms with a negative temperature in motional degrees of freedom for the first time.[11]

text: History[edit]

text: One of the first to discuss the possibility of an absolute minimal temperature was Robert Boyle. His 1665 New Experiments and Observations touching Cold, articulated the dispute known as the primum frigidum.[12] The concept was well known among naturalists of the time. Some contended an absolute minimum temperature occurred within earth (as one of the four classical elements), others within water, others air, and some more recently within nitre. But all of them seemed to agree that, "There is some body or other that is of its own nature supremely cold and by participation of which all other bodies obtain that quality."[13]

text: Limit to the "degree of cold"[edit]

text: The question whether there is a limit to the degree of coldness possible, and, if so, where the zero must be placed, was first addressed by the French physicist Guillaume Amontons in 1702, in connection with his improvements in the air-thermometer. His instrument indicated temperatures by the height at which a certain mass of air sustained a column of mercury—the volume, or "spring" of the air varying with temperature. Amontons therefore argued that the zero of his thermometer would be that temperature at which the spring of the air was reduced to nothing. He used a scale that marked the boiling-point of water at +73 and the melting-point of ice at 51, so that the zero was equivalent to about −240 on the Celsius scale.[14]

text: This close approximation to the modern value of −273.15 °C[1] for the zero of the air-thermometer was further improved upon in 1779 by Johann Heinrich Lambert, who observed that −270 °C (−454.00 °F; 3.15 K) might be regarded as absolute cold.[15]

text: Values of this order for the absolute zero were not, however, universally accepted about this period. Pierre-Simon Laplace and Antoine Lavoisier, in their 1780 treatise on heat, arrived at values ranging from 1,500 to 3,000 below the freezing-point of water, and thought that in any case it must be at least 600 below. John Dalton in his Chemical Philosophy gave ten calculations of this value, and finally adopted −3000 °C as the natural zero of temperature.

text: Lord Kelvin's work[edit]

text: After James Prescott Joule had determined the mechanical equivalent of heat, Lord Kelvin approached the question from an entirely different point of view, and in 1848 devised a scale of absolute temperature that was independent of the properties of any particular substance and was based on Carnot's theory of the Motive Power of Heat and data published by Henri Victor Regnault.[16] It followed from the principles on which this scale was constructed that its zero was placed at −273 °C, at almost precisely the same point as the zero of the air-thermometer.[14] This value was not immediately accepted; values ranging from −271.1 °C (−455.98 °F) to −274.5 °C (−462.10 °F), derived from laboratory measurements and observations of astronomical refraction, remained in use in the early 20th century.[17]

text: The race to absolute zero[edit]

text: With a better theoretical understanding of absolute zero, scientists were eager to reach this temperature in the lab.[18] By 1845, Michael Faraday had managed to liquefy most gases then known to exist, and reached a new record for lowest temperatures by reaching −130 °C (−202 °F; 143 K). Faraday believed that certain gases, such as oxygen, nitrogen, and hydrogen, were permanent gases and could not be liquified.[19] Decades later, in 1873 Dutch theoretical scientist Johannes Diderik van der Waals demonstrated that these gases could be liquefied, but only under conditions of very high pressure and very low temperatures. In 1877, Louis Paul Cailletet in France and Raoul Pictet in Switzerland succeeded in producing the first droplets of liquid air −195 °C (−319.0 °F; 78.1 K). This was followed in 1883 by the production of liquid oxygen −218 °C (−360.4 °F; 55.1 K) by the Polish professors Zygmunt Wróblewski and Karol Olszewski.

text: Scottish chemist and physicist James Dewar and the Dutch physicist Heike Kamerlingh Onnes took on the challenge to liquefy the remaining gases hydrogen and helium. In 1898, after 20 years of effort, Dewar was first to liquefy hydrogen, reaching a new low temperature record of −252 °C (−421.6 °F; 21.1 K). However Onnes, his rival, was the first to liquefy helium, in 1908, using several precooling stages and the Hampson–Linde cycle. He lowered the temperature to the boiling point of helium −269 °C (−452.20 °F; 4.15 K). By reducing the pressure of the liquid helium he achieved an even lower temperature, near 1.5 K. These were the coldest temperatures achieved on earth at the time and his achievement earned him the Nobel Prize in 1913.[20] Onnes would continue to study the properties of materials at temperatures near absolute zero, describing superconductivity and superfluids for the first time.

text: Very low temperatures[edit]

text: The average temperature of the universe today is approximately 2.73 kelvins (−270.42 °C; −454.76 °F), based on measurements of cosmic microwave background radiation.[21][22]

text: Absolute zero cannot be achieved, although it is possible to reach temperatures close to it through the use of cryocoolers, dilution refrigerators, and nuclear adiabatic demagnetization. The use of laser cooling has produced temperatures less than a billionth of a kelvin.[23] At very low temperatures in the vicinity of absolute zero, matter exhibits many unusual properties, including superconductivity, superfluidity, and Bose–Einstein condensation. To study such phenomena, scientists have worked to obtain even lower temperatures.

text:
The current world record was set in 1999 at 100 picokelvins (pK), or 0.000 000 000 1 of a kelvin, by cooling the nuclear spins in a piece of rhodium metal.[24]
In November 2000, nuclear spin temperatures below 100 pK were reported for an experiment at the Helsinki University of Technology's Low Temperature Lab in Espoo, Finland. However, this was the temperature of one particular degree of freedom – a quantum property called nuclear spin – not the overall average thermodynamic temperature for all possible degrees in freedom.[25][26]
In February 2003, the Boomerang Nebula was observed to have been releasing gases at a speed of 500,000 km/h (over 300,000 mph) for the last 1,500 years. This has cooled it down to approximately 1 K, as deduced by astronomical observation, which is the lowest natural temperature ever recorded.[27]
In May 2005, the European Space Agency proposed research in space to achieve femto-kelvin temperatures.[28]
In May 2006, the Institute of Quantum Optics at the University of Hannover gave details of technologies and benefits of femto-kelvin research in space.[29]
In January 2013, physicist Ulrich Schneider of the University of Munich in Germany reported to have achieved temperatures formally below absolute zero ("negative temperature") in gases. The gas is artificially forced out of equilibrium into a high potential energy state, which is however cold. When it then emits radiation it approaches the equilibrium, and can continue emitting despite reaching formal absolute zero; thus, the temperature is formally negative.[30]
In September 2014, scientists in the CUORE collaboration at the Laboratori Nazionali del Gran Sasso in Italy cooled a copper vessel with a volume of one cubic meter to 0.006 kelvins (−273.144 °C; −459.659 °F) for 15 days, setting a record for the lowest temperature in the known universe over such a large contiguous volume.[31]
In June 2015, experimental physicists at Massachusetts Institute of Technology (MIT) successfully cooled molecules in a gas of sodium potassium to a temperature of 500 nanokelvins, and it is expected to exhibit an exotic state of matter by cooling these molecules a bit further.[32]


document_title: List of murdered hip hop musicians

question_text: who was the first rapper to get shot

question_tokens: who was the first rapper to get shot

text: List of murdered hip hop musicians

text: The following is a list of notable hip hop musicians murdered since the genre began in the early 1970s.

text:
Name

Date

Age

Place of Death

Cause

Ref.

Scott La Rock

August 27, 1987

25

New York City, New York, U.S.

Shot and killed

[1]

Paul C.

July 1989

24

New York City, New York, U.S.

Shot and killed

[2]

D-Boy Rodriguez

October 6, 1990

22

Dallas, Texas, U.S.

Shot and killed

[3][4]

Charizma

December 16, 1993

20

Milpitas, California, U.S.

Shot and killed

[5][6]

Stretch

November 30, 1995

27

New York City, New York, U.S.

Shot and killed

[7]

Seagram

July 31, 1996

26

Oakland, California, U.S.

Shot and killed

[8][9]

Tupac Shakur

September 13, 1996

25

Las Vegas, Nevada, U.S.

Shot and killed

[10][11][12]

Yaki Kadafi

November 10, 1996

19

Orange, New Jersey, U.S.

Shot and killed

[13]

The Notorious B.I.G.

March 9, 1997

24

Los Angeles, California, U.S.

Shot and killed

[14][15][16]

Fat Pat

February 3, 1998

27

Houston, Texas, U.S.

Shot and killed

[17][18]

Big L

February 15, 1999

24

New York City, New York, U.S.

Shot and killed

[19][20][21]

Freaky Tah

March 28, 1999

27

New York City, New York, U.S.

Shot and killed

[22]

Bugz

May 21, 1999

22

Grand Rapids, Michigan, U.S.

Shot and run over

[23]

DJ Uncle Al

September 10, 2001

32

Miami, Florida, U.S.

Shot and killed

[24][25]

Jam Master Jay

October 30, 2002

37

New York City, New York, U.S.

Shot and killed

[26]

Sabotage

January 24, 2003

29

São Paulo, São Paulo, Brazil

Shot and killed

[27][28]

Camoflauge

May 19, 2003

21

Savannah, Georgia, U.S.

Shot and killed

[29]

Half a Mill

October 24, 2003

30

New York City, New York, U.S.

Shot and killed

[30]

Soulja Slim

November 26, 2003

26

New Orleans, Louisiana, U.S.

Shot and killed

[31][32]

Mac Dre

November 1, 2004

34

Kansas City, Missouri, U.S.

Shot and killed

[33]

Blade Icewood

April 19, 2005

28

Detroit, Michigan, U.S.

Shot and killed

[34]

Proof

April 11, 2006

32

Detroit, Michigan, U.S.

Shot and killed

[35][36][37]

Big Hawk

May 1, 2006

36

Houston, Texas, U.S.

Shot and killed

[38]

VL Mike

April 20, 2008

32

New Orleans, Louisiana, U.S.

Shot and killed

[39]

Dolla

May 18, 2009

21

Los Angeles, California, U.S.

Shot and killed

[40][41][42]

Magnolia Shorty

December 20, 2010

28

New Orleans, Louisiana, U.S.

Shot and killed

[43]

Bad News Brown

February 11, 2011

33

Montreal, Quebec, Canada

Murdered

[44]

Lil Phat

June 7, 2012

19

Sandy Springs, Georgia, U.S.

Shot and killed

[45]

Pavlos Fyssas

September 18, 2013

34

Keratsini, Athens, Greece

Stabbed to death

[46]

L'A Capone

September 26, 2013

17

Chicago, Illinois, U.S.

Shot and Killed

[47]

Doe B

December 28, 2013

22

Montgomery, Alabama, U.S.

Shot and killed

[48]

The Jacka

February 2, 2015

37

Oakland, California, U.S.

Shot and killed

[49]

Flabba

March 9, 2015

37

Alexandra, Gauteng, South Africa

Stabbed to death

[50]

Chinx

May 17, 2015

31

New York City, New York, U.S.

Shot and killed

[51]

Young Pappy

May 29, 2015

20

Chicago, Illinois, U.S.

Shot and killed

[52]

Bankroll Fresh

March 4, 2016

28

Atlanta, Georgia, U.S.

Shot and killed

[53]

3-2

November 10, 2016

44

Houston, Texas, U.S.

Shot and killed

[54]

Da Real Gee Money

September 10, 2017

20

Baton Rouge, Louisiana, U.S.

Shot and Killed

[55]

XXXTentacion

June 18, 2018

20

Deerfield Beach, Florida, U.S.

Shot and killed

[56]

Jimmy Wopo

June 18, 2018

21

Pittsburgh, Pennsylvania, U.S.

Shot and killed

[57]