title: Short Sunderland

text: The RAF received its first Sunderland Mark I in June 1938 when the second production aircraft ("L2159") was flown to 230 Squadron at RAF Seletar, Singapore. By the outbreak of war in Europe, in September 1939, RAF Coastal Command was operating 40 Sunderlands.


title: Short Sunderland

text: The main offensive load was up to of bombs (usually ), mines () or other stores that were hung on traversing racks under the wing centre section (to and from the "bomb room" in the fuselage). Later, depth charges (usually 250 lb) were added. By late 1940, two Vickers K machine guns had been added to new hatches that were inserted into the upper sides of the fuselage just aft of the wing, with appropriate slipstream deflectors. A second gun was added to the nose turret. New constant speed propellers and deicing boots were installed as well during 1940.


title: Short Sunderland

text: The Sunderland had difficulty in landing and taking off from rough water, but, other than in the open sea, it could be handled onto and off a short chop, by a skilled pilot. Many rescues were made, early in the war, of crews that were in the Channel having abandoned or ditched their aircraft, or abandoned their ship. During May 1941, during the Battle of Crete Sunderlands transported as many as 82 armed men from place to place in one load. Steep ocean swells were never attempted, however a calm ocean could be suitable for landing and takeoff.


title: Short Sunderland

text: Beginning in October 1941, Sunderlands were fitted with ASV Mark II "Air to Surface Vessel" radar. This was a primitive low frequency radar system operating at a wavelength of 1.5 m, that used a row of four prominent "stickleback" yagi antennas on top of the rear fuselage, two rows of four smaller aerials on either side of the fuselage beneath the stickleback antennas, and a single receiving aerial mounted under each wing outboard of the float and angled outward.


title: Short Sunderland

text: A total of 75 Sunderland Mark Is were built: 60 at Shorts' factories at Rochester and Belfast, Northern Ireland, and 15 by Blackburn Aircraft at Dumbarton.


title: Short Sunderland

text: In August 1941, production moved on to the Sunderland Mark II which used Pegasus XVIII engines with two-speed superchargers, producing 1,065 hp (794 kW) each.


title: Short Sunderland

text: The tail turret was changed to an FN.4A turret that retained the four .303 guns of its predecessor but provided twice the ammunition capacity with 1,000 rounds per gun. Late production Mark IIs also had an FN.7 dorsal turret, mounted offset to the right just behind the wings and fitted with twin .303 machine guns. The hand held guns behind the wing were removed in these versions.


title: Short Sunderland

text: Production quickly changed in December 1941 to the Sunderland Mark III, which featured a revised hull configuration which had been tested on a Mark I the previous June. This modification improved seaworthiness, which had suffered as the weight of the Sunderland increased with new marks and field changes. In earlier Sunderlands, the hull "step" that allows a flying boat to "unstick" from the surface of the sea was an abrupt one, but in the Mk III it was a curve upwards from the forward hull line.


title: Short Sunderland

text: The Mark III turned out to be the definitive Sunderland variant, with 461 built. Most were built by Shorts at Rochester and Belfast, a further 35 at a new (but temporary) Shorts plant at White Cross Bay, Windermere; while 170 were built by Blackburn Aircraft. The Sunderland Mark III proved to be one of the RAF Coastal Command's major weapons against the U-boats, along with the Consolidated Catalina.


title: Short Sunderland

text: As the U-boats began to use "Metox" passive receivers the ASV Mk II radar gave away the presence of aircraft and the number of sightings diminished drastically. The RAF response was to upgrade to the ASV Mk III, which operated in the 50 cm band, with antennas that could be faired into fewer more streamlined blisters. During the Mk III's life there were a large number of almost continuous improvements made, including the ASV Mk IIIA and four more machine guns in a fixed position in the wall of the forward fuselage just behind the turret (developed on RAAF aircraft first) with a simple bead and ring sight for the pilot. Sunderlands with upgraded ASV Mk III equipment were designated Mk IIIA.


title: Short Sunderland

text: Despite the 14-hour-long patrols expected of their crews, early Sunderland gunners were provided with only 500 rounds of ammunition each. Later 1,000 round ammunition boxes were installed in the turrets. The beam hatch guns were removed from Mk II aircraft but Mk IIIs and then Mk Is gained much more capable .50 (12.7 mm) guns, one each side.


title: Short Sunderland

text: Offensive weapons loads increased too. The introduction of the hydrostatically fused depth charge meant that additional weapons could be carried on the floor of the bomb room in wooden restraints, along with ammunition boxes of anti-personnel bombs that could be hand launched from various hatches to harass U-boat crews otherwise manning the twin 37 and dual quadruple 20 mm cannons with which U-boats were fitted.


title: Short Sunderland

text: As radar detection became more effective there were more night patrols to catch U-boats on the surface charging their batteries. Attacking in the dark was a problem that was solved by carrying one inch (25.4 mm), electrically initiated flares and dropping them out of the rear chute of the aircraft as it got close to the surface vessel. Sunderlands were never fitted with Leigh lights.


title: Short Sunderland

text: The Sunderland Mark IV was an outgrowth of the 1942 Air Ministry Specification R.8/42, for a generally improved Sunderland with more powerful Bristol Hercules engines, better defensive armament and other enhancements. The new Sunderland was intended for service in the Pacific. Although initially developed and two prototypes built as the "Sunderland Mark IV" it was different enough from the Sunderland line to be given a different name, the S.45 "Seaford".


title: Short Sunderland

text: Relative to the Mark III, the Mark IV had a stronger wing, larger tailplanes and a longer fuselage with some changes in hull form for better performance in the water. The armament was heavier with .50 inch (12.7 mm) machine guns and 20 mm Hispano cannon. The changes were so substantial that the new aircraft was redesignated the Short Seaford. Thirty production examples were ordered; the first delivered too late to see combat and only eight production Seafords were completed and never got beyond operational trials with the RAF.


title: Short Sunderland

text: The next production version was the Sunderland Mark V, which evolved out of crew concerns over the lack of power of the Pegasus engines. The weight creep (partly due to the addition of radar) that afflicted the Sunderland had resulted in running the Pegasus engines at combat power as a normal procedure and the overburdened engines had to be replaced regularly.


title: Short Sunderland

text: Australian Sunderland crews suggested that the Pegasus engines be replaced by Pratt & Whitney R-1830 Twin Wasp engines. The 14-cylinder engines provided 1,200 hp (895 kW) each and were already in use on RAF Consolidated Catalinas and Douglas Dakotas, and so logistics and maintenance were straightforward. Two Mark IIIs were taken off the production lines in early 1944 and fitted with the American engines. Trials were conducted in early 1944 and the conversion proved all that was expected.


title: Short Sunderland

text: The new engines with new Hamilton Hydromatic constant-speed fully feathering propellers provided greater performance with no real penalty in range. In particular, a Twin Wasp Sunderland could stay airborne if two engines were knocked out on the same wing while, in similar circumstances, a standard Mark III would steadily lose altitude. Production was switched to the Twin Wasp version and the first Mark V reached operational units in February 1945. Defensive armament fits were similar to those of the Mark III, but the Mark V was equipped with new centimetric ASV Mark VI C radar that had been used on some of the last production Mark IIIs as well.


title: Short Sunderland

text: A total of 155 Sunderland Mark Vs were built with another 33 Mark IIIs converted to Mark V specification. With the end of the war, large contracts for the Sunderland were cancelled and the last of these flying boats was delivered in June 1946, with a total production of 777 aircraft completed.


title: Short Sunderland

text: In late 1942, the British Overseas Airways Corporation (BOAC) obtained six Sunderland Mark IIIs, which had been de-militarised on the production line, for service as mail carriers to Nigeria and India, with accommodation for either 22 passengers with 2 tons of freight or 16 passengers with 3 tons of freight. Armament was removed, the gun positions being faired over, and simple seating fitted in place of the bunks. As such they were operated by BOAC and the RAF jointly from Poole to Lagos and Calcutta. Six more Sunderland IIIs were obtained in 1943. Minor modifications to the engine angles and flight angle resulted in a significant increase in the cruise speed, which was a relatively unimportant issue for the combat Sunderlands. In late 1944, the RNZAF acquired four new Sunderland Mk IIIs already configured for transport duties. In the immediate postwar period, these were used by New Zealand's National Airways Corporation to link South Pacific Islands in the "Coral Route" before TEAL Short Sandringhams took over after 1947.


title: Short Sunderland

text: At the war's end BOAC obtained more Mark IIIs and gradually came up with better accommodation for its passengers, in three configurations. Bench seats were removed, and civil-standard seating installed: The H.1 configuration had 16 seats on one deck, while the H.2 had an additional promenade deck, and the H.3 had 24 seats, or sleeping berths for 16. These conversions were given the name Hythe and BOAC operated 29 of them by the end of the war. In February 1946, the first of these, "G-AGJM", made a 35,313-mile route survey from Poole to Australia, New Zealand, Hong Kong, Shanghai and Tokyo in 206 flying hours. It was the first British civil flying boat to visit China and Japan.


title: Short Sunderland

text: A more refined civilian conversion of the Sunderland was completed by the manufacturer as the postwar Short Sandringham. The Sandringham Mk. I used Pegasus engines while the Mk. II used Twin Wasp engines.


title: Short Sunderland

text: Sunderland "T9044" was discovered on the seabed off Pembroke Dock in Wales in 2000. The site is protected and recovery of the aircraft is ongoing.


title: Short Sunderland

text: The wreck located by Calshot Divers at Calshot in 2010 is very likely to be that of "ML883" and not "PP118" as originally thought. This wreck site is awkward to dive due to its proximity to the Fawley Refinery, Solent shipping lane, Calshot RNLI station and public slipway.


title: I Gotta Feeling

text: "I Gotta Feeling" is the second single from the Black Eyed Peas' fifth album "The E.N.D.", produced by French DJ David Guetta. The song was released on May 21, 2009, and debuted at number two on the Canadian and "Billboard" Hot 100, behind the group's previous single "Boom Boom Pow", making the group one of 11 artists who have occupied the top two positions of the "Billboard" Hot 100 at the same time. It reached number one on the US charts and 20 charts worldwide.


title: I Gotta Feeling

text: The song was nominated for Record of the Year at the 52nd Grammy Awards and won the Grammy for Best Pop Performance by a Duo or Group with Vocals. "I Gotta Feeling" ranked fifth on the "Billboard" Hot 100 Songs of the Decade; later it would hold the number 8 spot on "Billboard"'s All-Time chart. The song was also nominated as Song of the Year at the 2010 World Music Awards. In March 2011, it became the first song in digital history to sell over 7 million digital copies in the United States. , "I Gotta Feeling" had over 9 million downloads in the country, and held the record as the most downloaded song on iTunes of all time. This also makes it the highest selling digital as well as non-charity single in the US ever.


title: I Gotta Feeling

text: "I Gotta Feeling" spent 14 consecutive weeks atop the "Billboard" Hot 100, making it the longest-running number-one single of 2009. The song was the third most successful song of the decade in Australia, as announced on January 7, 2010.


title: I Gotta Feeling

text: "I Gotta Feeling" was written and composed by all the members of the Black Eyed Peas (credited as William Adams, Allan Pineda, Jaime Gomez, and Stacy Ferguson) together with French producers David Guetta, Frédéric Riesterer (a.k.a. ), both of whom produced the song. Adams provided additional synthesizer work to the song. The song was recorded at Square Prod in Paris, France and Metropolis Studios in London, England, United Kingdom. "I Gotta Feeling" is the second single released from "The E.N.D" (2009). Interscope Records serviced the song to contemporary hit and rhythmic crossover radios on June 23, 2009, in the United States. In an interview with Annie Reuter of Marie Claire, will.i.am stated that "It's dedicated to all the party people out there in the world that want to go out and party. Mostly every song on the Black Eyed Peas record is painting a picture of our party life. It was a conscious decision to make this type of record. Times are really hard for a lot of people and you want to give them escape and you want to make them feel good about life, especially at these low points."


title: I Gotta Feeling

text: The song is an uptempo dance-pop song that runs a length of four minutes and 49 seconds. It follows in the inspirational dance-pop theme of "The E.N.D", being built upon the heavy use of Auto-Tune and futuristic synthesizers while running through a tick-tock rhythm. It is composed in the key of G major. The song begins in a restrained fashion then moves into a throbbing dance beat that changes patterns so that at least one reviewer thought it shifted tempos, although in fact the tempo does not change at all, suggesting the use of a click track in recording. It contains electronic influences. The song samples a beat from the song "Take a Dive" by Bryan Pringle. The "woo-hoo" line is sampled from The Police's song "Every Breath You Take". Ann Powers of "Los Angeles Times" noted the song's similarities to Five Stairsteps' song "Ooh Child", writing that it emulates the song's "use of a repetitive, warm vocal line to signify a good mood coming on." According to Jimmy Iovine of the Interscope Geffen A&M label group, the melody was inspired by the U2 song "I'll Go Crazy If I Don't Go Crazy Tonight": "I sent will.i.am over to the studio to do some remixes on I'll Go Crazy. He works on them for two weeks, comes back and writes I Gotta Feeling. The chords are U2 chords, 100 per cent. Will even told them."


title: I Gotta Feeling

text: "I Gotta Feeling" received generally positive reviews from music critics. David Balls, a writer for "Digital Spy", gave the song a four-star rating, writing that the song is "every bit as quirky as its predecessor ("Boom Boom Pow")". However, he compared it to Girls Aloud's "Biology", writing that they sound like a collection of musical ideas "that only makes sense after a few listens." Another writer for "Digital Spy", Nick Levine, praised "I Gotta Feeling" and "Rock That Body" as ace collaborations with French disc jockey David Guetta. Music critics like John Bush of "All Music Guide" and Andy Gill of "The Independent" labeled it as one of the album's best tracks. Ann Powers wrote a positive review about "I Gotta Feeling", noting that "the Peas do let in some human sweetness and light" on the song and that it uses "a repetitive, warm vocal line to signify a good mood coming on."


title: I Gotta Feeling

text: Ben Westhoff of "Las Vegas Weekly" dismissed the song as a blend of house, electro and dancehall beats that do not work compared to songs on "The E.N.D" like "Imma Be" and "One Tribe". Mike Schiller, a writer for "PopMatters", found the song to be irresistible, writing that it "is one of those dance tunes that's impossible to hate thanks to something like good natured naïveté". In his review of the album for "Stuff.co.nz", Chris Schultz dismissed the lyrics, writing that they were the worst since Flo Rida's "Right Round".


title: I Gotta Feeling

text: "The Observer-Dispatch" writer David T. Farr praised the song as "the summer track of 2009", writing that "It's one of those songs you grasp onto right away and crank up as the beat goes on, even the first time you hear it (guilty as charged)." Will Hines of "Consequence of Sound" shared similar feelings about "I Gotta Feeling", defining it as "chart baiting". Guy Blackman, a writer for "The Age", labeled "I Gotta Feeling" and "Boom Boom Pow" as further dumbed-down dance-pop songs. Bill Lamb of "About.com" gave the song a four-star rating, praising it for the difference of style from previous releases by the Black Eyed Peas and as a great summer song with a feel good mood., but he criticized the lack of lyrical depth and constant use of Auto-Tune. "Billboard"'s Chris Williams praised the song as their most mainstream release, writing that "they trade off on a simple, yet effective melody and message".


title: I Gotta Feeling

text: "I Gotta Feeling" followed in the international success of "The E.N.D"s lead single "Boom Boom Pow". In the United States, the song debuted on the "Billboard" Hot 100 at number two, behind "Boom Boom Pow", prompted by sales of 249,000 downloads. The song held at number two for another week before rising to the top position on the chart. On July 30, 2009, it was reported that the song, along with "Boom Boom Pow" helped earn the Black Eyed Peas the longest run at number one on the "Billboard" Hot 100 by a duo or group (17 weeks). The song stayed at number one on the chart for a total of fourteen weeks before being unseated by Jay Sean's "Down". The song, together with "Boom Boom Pow", earned the group a total of 26 consecutive weeks atop the Hot 100 chart while also earning them their longest running single on the chart, with a total of 56 weeks logged.


title: I Gotta Feeling

text: "I Gotta Feeling" also peaked at number one on several other "Billboard" charts, including Hot Digital Songs, Mainstream Top 40, and Radio Songs. It was the group's second single to sell over 6 million downloads in the United States, and was certified 7× Platinum on August 25, 2010, by the Recording Industry Association of America (RIAA) signifying sales of over 7 million units. It was the first song to reach sales of over 6 million (November 25, 2010), 7 million (March 20, 2011), 8 million (June 24, 2012), and 9 million (June 7, 2019). It also earned the accolade of being the best digital seller in history.


title: I Gotta Feeling

text: In Canada, the song debuted on the Canadian Hot 100 at number two behind "Boom Boom Pow", similar to its beginning run in the United States, on the week ending June 27, 2009. The next week, it rose to number one following a surge in airplay, where it maintained that position for 16 consecutive weeks, setting the record for longest run at number one since the chart's inception in 2007. The song was present on the chart for a total of 76 weeks, setting the record for longest stay on the chart. The song was certified Diamond by Music Canada for sales of over 800,000 digital downloads.


title: I Gotta Feeling

text: "I Gotta Feeling" fared similarly in international markets. The song had a slower rise in the United Kingdom, where it debuted at number 70 on the week ending June 20, 2009. It quickly picked up momentum, moving into the top five in its fifth week on the chart. On the week ending August 8, 2009, the song peaked at number one, becoming the group's third number one and staying there for two non-consecutive weeks. "I Gotta Feeling" held within the top ten for 16 consecutive weeks and lasted on the chart for a total of 76 weeks. The song was certified 4× Platinum by the British Phonographic Industry on June 3, 2022, for sales and streams of 2.4 million units. "I Gotta Feeling" became the first song to sell over one million units based solely on the strength of digital downloads, and has sold over 1.44 million copies in the United Kingdom as of May 2014. In Ireland, the song peaked at number one and held that position for 12 non-consecutive weeks, falling to number two on the week of August 27, 2009, after six weeks in the top position. It rose to number one the following week and held that position for another six weeks. In Sweden, the song debuted on the chart at number 36 on the week ending July 19, 2009. It quickly entered the top ten and peaked at number one in its seventh week on the chart. "I Gotta Feeling" maintained its position there for eight consecutive weeks and stayed present on the charts for a total of 87 weeks. The single was certified double platinum for sales of 40,000 units. In Germany, the song debuted on the chart at number seven and rose to number three two weeks later.


title: I Gotta Feeling

text: "I Gotta Feeling" peaked at number one in countries including Australia, Austria, Belgium, Denmark, Italy, The Netherlands, and New Zealand. The song reached top five peak positions in Finland, France, Norway, and Spain. It has sold over seven million units worldwide in 2009 and an additional six million in 2010, as reported by the IFPI.


title: I Gotta Feeling

text: On September 8, 2009, the song was performed (with slight modification) by the Black Eyed Peas for the taping of the Kick-off Party for the 24th season of "The Oprah Winfrey Show", with 21,000 fans performing a dance on the "Magnificent Mile" portion of Michigan Avenue in Chicago, Illinois. They also performed the song at the 52nd Grammy Awards nomination announcement ceremony with David Guetta (a remix edit by David Guetta appears on his album, "One Love"). The Black Eyed Peas also performed the song during a concert at Mont Kiara, Kuala Lumpur, Malaysia in 2009. Being the headliners of the Super Bowl XLV halftime show, the Black Eyed Peas sang "I Gotta Feeling" in front of more than 100,000 fans at Cowboys Stadium. On April 29, 2011, they performed the song along with others at the "i.am.FIRST" event at the FIRST Robotics Competition World Championships. For Queen Elizabeth II's Diamond Jubilee Concert, will.i.am and Jessie J sang a duet of "I Gotta Feeling". At the last part of the 2019 Southeast Asian Games closing ceremony at the New Clark City Athletics Stadium in the Philippines, this song was performed again, except that Fergie's part was sung by J Rey Soul (stage name of Jessica Reynoso), whom apl.de.ap introduced to the audience.


title: I Gotta Feeling

text: The official final version was released on June 2 on Dipdive and on June 15 on iTunes. There is both a censored version and an explicit version of the music video and a live performance of the explicit video. The video starts with scenes in Hollywood Blvd. and then showing will.i.am combing his hair and Fergie putting on make-up while wearing lingerie. It also shows Taboo checking his messages on Dipdive and apl.de.ap checking his text messages. Then it cuts to the party as the first verse starts. The video ends with a large sign with human-sized letters that reads "The E.N.D" The video is directed by Mikey Mee of "Little Minx" and features guest appearances by David Guetta, Kid Cudi, members of the indie rock band Gossip, the designer duo Dean and Dan Caten of Dsquared and "RuPaul's Drag Race" alumni Ongina.


title: I Gotta Feeling

text: Credits adapted from the liner notes of "The E.N.D", Interscope Records, in association with will.i.am Music Group.


title: Currywurst

text: Currywurst () is a fast food dish of German origin consisting of steamed, fried sausage, usually pork (), typically cut into bite-sized chunks and seasoned with curry ketchup, a sauce based on spiced ketchup or tomato paste topped with curry powder, or a ready-made ketchup seasoned with curry and other spices. The dish is often served with fries.


title: Currywurst

text: The invention of currywurst is attributed to Herta Heuwer in Berlin in 1949, after she obtained ketchup (or possibly Worcestershire sauce) and curry powder from British soldiers in Germany. She mixed these ingredients with other spices and poured it over grilled pork sausage. Heuwer started selling the cheap but filling snack at a street stand in the Charlottenburg district of Berlin, where it became popular with construction workers rebuilding the devastated city. She patented her sauce under the name "Chillup" in 1951. At its height the stand was selling 10,000 servings per week. She later opened a small restaurant which operated until 1974. On 30 June 2013 Heuwer's 100th birthday was celebrated with a Google Doodle.


title: Currywurst

text: Today, currywurst is often sold as a take-out/take-away food, Schnellimbisse (snack stands), at diners or "greasy spoons," on children's menus in restaurants, or as a street food and usually served with french fries or bread rolls (Brötchen). It is popular all over Germany but especially in the metropolitan areas of Berlin, Hamburg and the Ruhr Area. Considerable variation, both in the type of sausage used and the ingredients of the sauce, occurs between these areas. Common variations include the addition of paprika or chopped onions; halal food stands often prepare currywurst with beef sausage. Often currywurst is sold in food booths, sometimes using a special machine to slice it into pieces, and served on a paper plate with a little wooden or plastic fork, mostly a Currywurst fork. It is also sold as a supermarket-shelf product to prepare at home.


title: Currywurst

text: The Deutsches Currywurst Museum estimated that 800 million currywursts are eaten every year in Germany, with 70 million in Berlin alone. The Volkswagen plant at Wolfsburg runs its own butchery producing about 7 million Volkswagen currywursts per year, serving many directly to Volkswagen employees.


title: Currywurst

text: The currywurst is an icon of German popular culture. Former Chancellor Gerhard Schröder is a noted fan of currywurst. By tradition, every candidate for the mayor of Berlin is photographed at a currywurst stand.


title: Currywurst

text: The 1993 novel "Die Entdeckung der Currywurst" (English title: "The Invention of Curried Sausage", ) by Uwe Timm was made into a 1998 play and a 2008 film both of the same name. The plot is based on an alternative but unproven theory that currywurst was invented in Hamburg.


title: Currywurst

text: The Deutsches Currywurst Museum opened in Berlin on 15 August 2009, commemorating the 60th anniversary of its creation. Curator Martin Loewer said "No other national German dish inspires so much history and has so many well-known fans". The museum received approximately 350,000 visitors annually. It permanently closed on 21 December 2018.


title: Currywurst

text: In 2019 Berlin State Mint issued a commemorative currywurst coin celebrating the 70 years since the savoury snack was first sold in Berlin by Herta Heuwer. The silver alloy coin features two currywursts pierced with a wooden chip fork and poured with the sauce (coloured by print), and Herta Heuwer in the background (caption: 70 Jahre Currywurst). The other side of the coin shows the Brandenburg Gate (caption: Münze Berlin, 2019).


title: Interrupt

text: In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to "interrupt" currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted, the processor will suspend its current activities, save its state, and execute a function called an "interrupt handler" (or an "interrupt service routine", ISR) to deal with the event. This interruption is often temporary, allowing the software to resume normal activities after the interrupt handler finishes, although the interrupt could instead indicate a fatal error.


title: Interrupt

text: Interrupts are commonly used by hardware devices to indicate electronic or physical state changes that require time-sensitive attention. Interrupts are also commonly used to implement computer multitasking, especially in real-time computing. Systems that use interrupts in these ways are said to be interrupt-driven.


title: Interrupt

text: Interrupt signals may be issued in response to hardware or software events. These are classified as hardware interrupts or software interrupts, respectively. For any particular processor, the number of interrupt types is limited by the architecture.


title: Interrupt

text: A hardware interrupt is a condition related to the state of the hardware that may be signaled by an external hardware device, e.g., an interrupt request (IRQ) line on a PC, or detected by devices embedded in processor logic (e.g., the CPU timer in IBM System/370), to communicate that the device needs attention from the operating system (OS) or, if there is no OS, from the "bare-metal" program running on the CPU. Such external devices may be part of the computer (e.g., disk controller) or they may be external peripherals. For example, pressing a keyboard key or moving a mouse plugged into a PS/2 port triggers hardware interrupts that cause the processor to read the keystroke or mouse position.


title: Interrupt

text: Hardware interrupts can arrive asynchronously with respect to the processor clock, and at any time during instruction execution. Consequently, all incoming hardware interrupt signals are conditioned by synchronizing them to the processor clock, and acted upon only at instruction execution boundaries.


title: Interrupt

text: In many systems, each device is associated with a particular IRQ signal. This makes it possible to quickly determine which hardware device is requesting service, and to expedite servicing of that device.


title: Interrupt

text: On some older systems, such as the 1964 CDC 3600, all interrupts went to the same location, and the OS used a specialized instruction to determine the highest-priority outstanding unmasked interrupt. On contemporary systems, there is generally a distinct interrupt routine for each type of interrupt (or for each interrupt source), often implemented as one or more interrupt vector tables.


title: Interrupt

text: To "mask" an interrupt is to disable it, so it is deferred or ignored by the processor, while to "unmask" an interrupt is to enable it.


title: Interrupt

text: Processors typically have an internal "interrupt mask" register, which allows selective enabling (and disabling) of hardware interrupts. Each interrupt signal is associated with a bit in the mask register. On some systems, the interrupt is enabled when the bit is set, and disabled when the bit is clear. On others, the reverse is true, and a set bit disables the interrupt. When the interrupt is disabled, the associated interrupt signal may be ignored by the processor, or it may remain pending. Signals which are affected by the mask are called "maskable interrupts".


title: Interrupt

text: Some interrupt signals are not affected by the interrupt mask and therefore cannot be disabled; these are called "non-maskable interrupts" (NMIs). These indicate high-priority events which cannot be ignored under any circumstances, such as the timeout signal from a watchdog timer.


title: Interrupt

text: A "spurious interrupt" is a hardware interrupt for which no source can be found. The term "phantom interrupt" or "ghost interrupt" may also used to describe this phenomenon. Spurious interrupts tend to be a problem with a wired-OR interrupt circuit attached to a level-sensitive processor input. Such interrupts may be difficult to identify when a system misbehaves.


title: Interrupt

text: In a wired-OR circuit, parasitic capacitance charging/discharging through the interrupt line's bias resistor will cause a small delay before the processor recognizes that the interrupt source has been cleared. If the interrupting device is cleared too late in the interrupt service routine (ISR), there won't be enough time for the interrupt circuit to return to the quiescent state before the current instance of the ISR terminates. The result is the processor will think another interrupt is pending, since the voltage at its interrupt request input will be not high or low enough to establish an unambiguous internal logic 1 or logic 0. The apparent interrupt will have no identifiable source, hence the "spurious" moniker.


title: Interrupt

text: A spurious interrupt may also be the result of electrical anomalies due to faulty circuit design, high noise levels, crosstalk, timing issues, or more rarely, device errata.


title: Interrupt

text: A spurious interrupt may result in system deadlock or other undefined operation if the ISR doesn't account for the possibility of such an interrupt occurring. As spurious interrupts are mostly a problem with wired-OR interrupt circuits, good programming practice in such systems is for the ISR to check all interrupt sources for activity and take no action (other than possibly logging the event) if none of the sources is interrupting.


title: Interrupt

text: A software interrupt is requested by the processor itself upon executing particular instructions or when certain conditions are met. Every software interrupt signal is associated with a particular interrupt handler.


title: Interrupt

text: A software interrupt may be intentionally caused by executing a special instruction which, by design, invokes an interrupt when executed. Such instructions function similarly to subroutine calls and are used for a variety of purposes, such as requesting operating system services and interacting with device drivers (e.g., to read or write storage media). Software interrupts may also be triggered by program execution errors or by the virtual memory system.


title: Interrupt

text: Typically, the operating system kernel will catch and handle such interrupts. Some interrupts are handled transparently to the program - for example, the normal resolution of a page fault is to make the required page accessible in physical memory. But in other cases such as a segmentation fault the operating system executes a process callback. On Unix-like operating systems this involves sending a signal such as SIGSEGV, SIGBUS, SIGILL or SIGFPE, which may either call a signal handler or execute a default action (terminating the program). On Windows the callback is made using Structured Exception Handling with an exception code such as STATUS_ACCESS_VIOLATION or STATUS_INTEGER_DIVIDE_BY_ZERO.


title: Interrupt

text: In a kernel process, it is often the case that some types of software interrupts are not supposed to happen. If they occur nonetheless, an operating system crash may result.


title: Interrupt

text: The terms "interrupt", "trap", "exception", "fault", and "abort" are used to distinguish types of interrupts, although "there is no clear consensus as to the exact meaning of these terms". The term "trap" may refer to any interrupt, to any software interrupt, to any synchronous software interrupt, or only to interrupts caused by instructions with "trap" in their names. In some usages, the term "trap" refers specifically to a breakpoint intended to initiate a context switch to a monitor program or debugger. It may also refer to a synchronous interrupt caused by an exceptional condition (e.g., division by zero, invalid memory access, illegal opcode), although the term "exception" is more common for this.


title: Interrupt

text: x86 divides interrupts into (hardware) "interrupts" and software "exceptions", and identifies three types of exceptions: faults, traps, and aborts. (Hardware) interrupts are interrupts triggered asynchronously by an I/O device, and allow the program to be restarted with no loss of continuity. A fault is restartable as well but is tied to the synchronous execution of an instruction - the return address points to the faulting instruction. A trap is similar to a fault except that the return address points to the instruction to be executed after the trapping instruction; one prominent use is to implement system calls. An abort is used for severe errors, such as hardware errors and illegal values in system tables, and often does not allow a restart of the program.


title: Interrupt

text: ARM uses the term "exception" to refer to all types of interrupts, and divides exceptions into (hardware) "interrupts", "aborts", "reset", and exception-generating instructions. Aborts correspond to x86 exceptions and may be prefetch aborts (failed instruction fetches) or data aborts (failed data accesses), and may be synchronous or asynchronous. Asynchronous aborts may be precise or imprecise. MMU aborts (page faults) are synchronous.


title: Interrupt

text: Each interrupt signal input is designed to be triggered by either a logic signal level or a particular signal edge (level transition). Level-sensitive inputs continuously request processor service so long as a particular (high or low) logic level is applied to the input. Edge-sensitive inputs react to signal edges: a particular (rising or falling) edge will cause a service request to be latched; the processor resets the latch when the interrupt handler executes.


title: Interrupt

text: A "level-triggered interrupt" is requested by holding the interrupt signal at its particular (high or low) active logic level. A device invokes a level-triggered interrupt by driving the signal to and holding it at the active level. It negates the signal when the processor commands it to do so, typically after the device has been serviced.


title: Interrupt

text: The processor samples the interrupt input signal during each instruction cycle. The processor will recognize the interrupt request if the signal is asserted when sampling occurs.


title: Interrupt

text: Level-triggered inputs allow multiple devices to share a common interrupt signal via wired-OR connections. The processor polls to determine which devices are requesting service. After servicing a device, the processor may again poll and, if necessary, service other devices before exiting the ISR.


title: Interrupt

text: An "edge-triggered interrupt" is an interrupt signaled by a level transition on the interrupt line, either a falling edge (high to low) or a rising edge (low to high). A device wishing to signal an interrupt drives a pulse onto the line and then releases the line to its inactive state. If the pulse is too short to be detected by polled I/O then special hardware may be required to detect it. The important part of edge triggering is that the signal must transition to trigger the interrupt; for example, if the signal was high-low-low, there would only be one falling edge interrupt triggered, and the continued low level would not trigger a further interrupt. The signal must return to the high level and fall again in order to trigger a further interrupt. This contrasts with a level trigger where the low level would continue to create interrupts (if they are enabled) until the signal returns to its high level.


title: Interrupt

text: Computers with edge-triggered interrupts may include an "interrupt register" that retains the status of pending interrupts. Systems with interrupt registers generally have interrupt mask registers as well.


title: Interrupt

text: The processor samples the interrupt trigger signals or interrupt register during each instruction cycle, and will process the highest priority enabled interrupt found.


title: Interrupt

text: Regardless of the triggering method, the processor will begin interrupt processing at the next instruction boundary following a detected trigger, thus ensuring:


title: Interrupt

text: Interrupts may be implemented in hardware as a distinct component with control lines, or they may be integrated into the .


title: Interrupt

text: If implemented in hardware as a distinct component, an interrupt controller circuit such as the IBM PC's Programmable Interrupt Controller (PIC) may be connected between the interrupting device and the processor's interrupt pin to multiplex several sources of interrupt onto the one or two CPU lines typically available. If implemented as part of the memory controller, interrupts are mapped into the system's memory address space.


title: Interrupt

text: Multiple devices may share an edge-triggered interrupt line if they are designed to. The interrupt line must have a pull-down or pull-up resistor so that when not actively driven it settles to its inactive state, which is the default state of it. Devices signal an interrupt by briefly driving the line to its non-default state, and let the line float (do not actively drive it) when not signaling an interrupt. This type of connection is also referred to as open collector. The line then carries all the pulses generated by all the devices. (This is analogous to the pull cord on some buses and trolleys that any passenger can pull to signal the driver that they are requesting a stop.) However, interrupt pulses from different devices may merge if they occur close in time. To avoid losing interrupts the CPU must trigger on the trailing edge of the pulse (e.g. the rising edge if the line is pulled up and driven low). After detecting an interrupt the CPU must check all the devices for service requirements.


title: Interrupt

text: Edge-triggered interrupts do not suffer the problems that level-triggered interrupts have with sharing. Service of a low-priority device can be postponed arbitrarily, while interrupts from high-priority devices continue to be received and get serviced. If there is a device that the CPU does not know how to service, which may raise spurious interrupts, it won't interfere with interrupt signaling of other devices. However, it is easy for an edge-triggered interrupt to be missed - for example, when interrupts are masked for a period - and unless there is some type of hardware latch that records the event it is impossible to recover. This problem caused many "lockups" in early computer hardware because the processor did not know it was expected to do something. More modern hardware often has one or more interrupt status registers that latch interrupts requests; well-written edge-driven interrupt handling code can check these registers to ensure no events are missed.


title: Interrupt

text: The elderly Industry Standard Architecture (ISA) bus uses edge-triggered interrupts, without mandating that devices be able to share IRQ lines, but all mainstream ISA motherboards include pull-up resistors on their IRQ lines, so well-behaved ISA devices sharing IRQ lines should just work fine. The parallel port also uses edge-triggered interrupts. Many older devices assume that they have exclusive use of IRQ lines, making it electrically unsafe to share them.


title: Interrupt

text: There are 3 ways multiple devices "sharing the same line" can be raised. First is by exclusive conduction (switching) or exclusive connection (to pins). Next is by bus (all connected to the same line listening): cards on a bus must know when they are to talk and not talk (i.e., the ISA bus). Talking can be triggered in two ways: by accumulation latch or by logic gates. Logic gates expect a continual data flow that is monitored for key signals. Accumulators only trigger when the remote side excites the gate beyond a threshold, thus no negotiated speed is required. Each has its speed versus distance advantages. A trigger, generally, is the method in which excitation is detected: rising edge, falling edge, threshold (oscilloscope can trigger a wide variety of shapes and conditions).


title: Interrupt

text: Triggering for software interrupts must be built into the software (both in OS and app). A 'C' app has a trigger table (a table of functions) in its header, which both the app and OS know of and use appropriately that is not related to hardware. However do not confuse this with hardware interrupts which signal the CPU (the CPU enacts software from a table of functions, similarly to software interrupts).


title: Interrupt

text: Multiple devices sharing an interrupt line (of any triggering style) all act as spurious interrupt sources with respect to each other. With many devices on one line, the workload in servicing interrupts grows in proportion to the square of the number of devices. It is therefore preferred to spread devices evenly across the available interrupt lines. Shortage of interrupt lines is a problem in older system designs where the interrupt lines are distinct physical conductors. Message-signaled interrupts, where the interrupt line is virtual, are favored in new system architectures (such as PCI Express) and relieve this problem to a considerable extent.


title: Interrupt

text: Some devices with a poorly designed programming interface provide no way to determine whether they have requested service. They may lock up or otherwise misbehave if serviced when they do not want it. Such devices cannot tolerate spurious interrupts, and so also cannot tolerate sharing an interrupt line. ISA cards, due to often cheap design and construction, are notorious for this problem. Such devices are becoming much rarer, as hardware logic becomes cheaper and new system architectures mandate shareable interrupts.


title: Interrupt

text: Some systems use a hybrid of level-triggered and edge-triggered signaling. The hardware not only looks for an edge, but it also verifies that the interrupt signal stays active for a certain period of time.


title: Interrupt

text: A common use of a hybrid interrupt is for the NMI (non-maskable interrupt) input. Because NMIs generally signal major – or even catastrophic – system events, a good implementation of this signal tries to ensure that the interrupt is valid by verifying that it remains active for a period of time. This 2-step approach helps to eliminate false interrupts from affecting the system.


title: Interrupt

text: A "message-signaled interrupt" does not use a physical interrupt line. Instead, a device signals its request for service by sending a short message over some communications medium, typically a computer bus. The message might be of a type reserved for interrupts, or it might be of some pre-existing type such as a memory write.


title: Interrupt

text: Message-signalled interrupts behave very much like edge-triggered interrupts, in that the interrupt is a momentary signal rather than a continuous condition. Interrupt-handling software treats the two in much the same manner. Typically, multiple pending message-signaled interrupts with the same message (the same virtual interrupt line) are allowed to merge, just as closely spaced edge-triggered interrupts can merge.


title: Interrupt

text: Message-signalled interrupt vectors can be shared, to the extent that the underlying communication medium can be shared. No additional effort is required.


title: Interrupt

text: Because the identity of the interrupt is indicated by a pattern of data bits, not requiring a separate physical conductor, many more distinct interrupts can be efficiently handled. This reduces the need for sharing. Interrupt messages can also be passed over a serial bus, not requiring any additional lines.


title: Interrupt

text: In a push button analogy applied to computer systems, the term "doorbell" or "doorbell interrupt" is often used to describe a mechanism whereby a software system can signal or notify a computer hardware device that there is some work to be done. Typically, the software system will place data in some well-known and mutually agreed upon memory locations, and "ring the doorbell" by writing to a different memory location. This different memory location is often called the doorbell region, and there may even be multiple doorbells serving different purposes in this region. It is this act of writing to the doorbell region of memory that "rings the bell" and notifies the hardware device that the data are ready and waiting. The hardware device would now know that the data are valid and can be acted upon. It would typically write the data to a hard disk drive, or send them over a network, or encrypt them, etc.


title: Interrupt

text: The term "doorbell interrupt" is usually a misnomer. It is similar to an interrupt, because it causes some work to be done by the device; however, the doorbell region is sometimes implemented as a polled region, sometimes the doorbell region writes through to physical device registers, and sometimes the doorbell region is hardwired directly to physical device registers. When either writing through or directly to physical device registers, this may cause a real interrupt to occur at the device's central processor unit (CPU), if it has one.


title: Interrupt

text: In multiprocessor systems, a processor may send an interrupt request to another processor via inter-processor interrupts (IPI).


title: Interrupt

text: Interrupts provide low overhead and good latency at low load, but degrade significantly at high interrupt rate unless care is taken to prevent several pathologies. The phenomenon where the overall system performance is severely hindered by excessive amounts of processing time spent handling interrupts is called an interrupt storm.


title: Interrupt

text: There are various forms of livelocks, when the system spends all of its time processing interrupts to the exclusion of other required tasks.


title: Interrupt

text: Under extreme conditions, a large number of interrupts (like very high network traffic) may completely stall the system. To avoid such problems, an operating system must schedule network interrupt handling as carefully as it schedules process execution.


title: Interrupt

text: With multi-core processors, additional performance improvements in interrupt handling can be achieved through receive-side scaling (RSS) when multiqueue NICs are used. Such NICs provide multiple receive queues associated to separate interrupts; by routing each of those interrupts to different cores, processing of the interrupt requests triggered by the network traffic received by a single NIC can be distributed among multiple cores. Distribution of the interrupts among cores can be performed automatically by the operating system, or the routing of interrupts (usually referred to as "IRQ affinity") can be manually configured.


title: Interrupt

text: A purely software-based implementation of the receiving traffic distribution, known as "receive packet steering" (RPS), distributes received traffic among cores later in the data path, as part of the interrupt handler functionality. Advantages of RPS over RSS include no requirements for specific hardware, more advanced traffic distribution filters, and reduced rate of interrupts produced by a NIC. As a downside, RPS increases the rate of inter-processor interrupts (IPIs). "Receive flow steering" (RFS) takes the software-based approach further by accounting for application locality; further performance improvements are achieved by processing interrupt requests by the same cores on which particular network packets will be consumed by the targeted application.


title: Interrupt

text: Interrupts are commonly used to service hardware timers, transfer data to and from storage (e.g., disk I/O) and communication interfaces (e.g., UART, Ethernet), handle keyboard and mouse events, and to respond to any other time-sensitive events as required by the application system. Non-maskable interrupts are typically used to respond to high-priority requests such as watchdog timer timeouts, power-down signals and traps.


title: Interrupt

text: Hardware timers are often used to generate periodic interrupts. In some applications, such interrupts are counted by the interrupt handler to keep track of absolute or elapsed time, or used by the OS task scheduler to manage execution of running processes, or both. Periodic interrupts are also commonly used to invoke sampling from input devices such as analog-to-digital converters, incremental encoder interfaces, and GPIO inputs, and to program output devices such as digital-to-analog converters, motor controllers, and GPIO outputs.


title: Interrupt

text: A disk interrupt signals the completion of a data transfer from or to the disk peripheral; this may cause a process to run which is waiting to read or write. A power-off interrupt predicts imminent loss of power, allowing the computer to perform an orderly shut-down while there still remains enough power to do so. Keyboard interrupts typically cause keystrokes to be buffered so as to implement typeahead.


title: Interrupt

text: Interrupts are sometimes used to emulate instructions which are unimplemented on some computers in a product family. For example floating point instructions may be implemented in hardware on some systems and emulated on lower-cost systems. In the latter case, execution of an unimplemented floating point instruction will cause an "illegal instruction" exception interrupt. The interrupt handler will implement the floating point function in software and then return to the interrupted program as if the hardware-implemented instruction had been executed. This provides application software portability across the entire line.


title: Interrupt

text: Interrupts are similar to signals, the difference being that signals are used for inter-process communication (IPC), mediated by the kernel (possibly via system calls) and handled by processes, while interrupts are mediated by the processor and handled by the kernel. The kernel may pass an interrupt as a signal to the process that caused it (typical examples are SIGSEGV, SIGBUS, SIGILL and SIGFPE).


title: Interrupt

text: Hardware interrupts were introduced as an optimization, eliminating unproductive waiting time in polling loops, waiting for external events. The first system to use this approach was the DYSEAC, completed in 1954, although earlier systems provided error trap functions.


title: Interrupt

text: The UNIVAC 1103A computer is generally credited with the earliest use of interrupts in 1953. Earlier, on the UNIVAC I (1951) "Arithmetic overflow either triggered the execution of a two-instruction fix-up routine at address 0, or, at the programmer's option, caused the computer to stop." The IBM 650 (1954) incorporated the first occurrence of interrupt masking. The National Bureau of Standards DYSEAC (1954) was the first to use interrupts for I/O. The IBM 704 was the first to use interrupts for debugging, with a "transfer trap", which could invoke a special routine when a branch instruction was encountered. The MIT Lincoln Laboratory TX-2 system (1957) was the first to provide multiple levels of priority interrupts.


title: Hugo Speer

text: Hugo Speer was born in Harrogate in the then West Riding of Yorkshire and educated at Harrogate Grammar School. He studied acting at the Arts Educational Schools, London.


title: Hugo Speer

text: Speer began his acting career appearing in the TV series "McCallum", "The Bill", and "Heartbeat". He played a minor role in the film "Bhaji on the Beach" before his first notable appearance as Guy in the film "The Full Monty". Following this film's worldwide success he went on to appear in "Swing" (1999), "Deathwatch" and "The Interpreter" (playing Nicole Kidman's brother). However, most of his work has been on TV, including sitcom "Men Behaving Badly", dramas "Clocking Off", "The Last Detective", "Boudica" (2003), and "The Rotters' Club" (2005), as well as the 2005 BBC adaptation of Dickens' "Bleak House". In 2006, he appeared in the postal worker drama "Sorted". In 2008, he starred alongside Martine McCutcheon in "Echo Beach". In 2011 he played a repairman whose repairs "come to life" in the supernatural drama "Haven", based on a Stephen King story. Speer also provides narration for ITV series, "Cops with Cameras", Channel 5's "The Bachelor", Channel 4 series "" and the BBC series "Seaside Rescue".


title: Hugo Speer

text: Since 2010 he has played the lead character of DCI John Stone in eight series of the BBC Radio 4 police drama "Stone". From 2013 to 2014 he starred as Inspector Valentine in the new version of "Father Brown" on BBC TV in the first series and the first episode of the second series. He made a return appearance in the 2020 episode 8.10 "The Tower of Lost Souls"


title: Hugo Speer

text: Starting in 2014, Speer appeared as Captain Treville in "The Musketeers". The series concluded in 2016.


title: Hugo Speer

text: Since 2018 he has played the character Lucius in the historical fantasy drama series "Britannia", which is produced by Sky Atlantic and Amazon Prime.


title: Hugo Speer

text: In 2010 Hugo Speer made his directorial début with the short film "MAM" starring Josie Lawrence, Paul Barber and Ronan Carter. The family drama about a 12-year-old boy was scripted by Vivienne Harvey. It was produced by Vigo Films and shot mostly in Sheffield.


title: Hugo Speer

text: In 2009, Speer was involved in a car accident that saw him crash his BMW into a traffic island while driving after drinking over the legal limit. He was returning from a wake. No one was hurt in the incident and Speer was banned from driving for eighteen months.


title: Hugo Speer

text: Speer moved to London after his success in "The Full Monty" and lived there for fifteen years but moved back to his native North Yorkshire. His pastimes include falconry, walking and music. He is a supporter of Leeds United.


title: Hugo Speer

text: He is friends with fellow actor Andrew Scarborough, whom he worked with in the "Hearts and Bones" for two series. Speer and Scarborough have known each other since they were children.


title: Hugo Speer

text: In July 2022, Speer was sacked from a planned follow-up television version of "The Full Monty" made by Disney+ following allegations of "inappropriate conduct". A spokesperson for the actor said Speer denies the allegations and will challenge them.


title: Lena Hall

text: Celina Consuela Gabriella Carvajal (born January 30, 1980), known professionally as Lena Hall, is an American actress and singer. She originated the role of Nicola in the Broadway musical "Kinky Boots" and won the Tony Award for her performance as Yitzhak in the 2014 revival of "Hedwig and the Angry Inch", which also earned her a Grammy nomination for the musical's official album. She made history by becoming the first person to play both Hedwig and Yitzhak in the same production during the national tour of the musical in 2016. Her other Broadway credits include "Cats", "42nd Street", "Dracula, the Musical" and "Tarzan, the Musical". Hall has also starred in Off-Broadway productions such as "Radiant Baby", "Bedbugs!!!", "Rooms: A Rock Romance", "The Toxic Avenger", "Prometheus Bound", "Chix6", and the 2017 original play "How to Transcend a Happy Marriage".


title: Lena Hall

text: Hall has appeared in films such as "Sex and the City" (2008), "The Graduates" (2008), "Born from the Foot" (2009), "The Big Gay Musical" (2009), and "Becks" (2017), for which she received widespread critical acclaim. She has also appeared on TV shows like ABC's "All My Children", HBO's "Girls", Amazon Prime's "Good Girls Revolt", and voiced the role of Countess Coloratura on "". In 2020, she joined the cast of TNT's science fiction epic "Snowpiercer" as Miss Audrey.


title: Lena Hall

text: Hall was the lead singer of the band "The Deafening", they released an album with original songs in 2012 titled "Central Booking". In 2015, Hall released her first solo album, "Sin & Salvation: Live At the Carlyle".


title: Lena Hall

text: Celina Consuela Gabriella Carvajal was born in San Francisco, California, on January 30, 1980, to Carlos and Carolyn ("née" Houser) Carvajal. Her father is a ballet dancer, choreographer and the co-artistic director for the annual San Francisco Ethnic Dance Festival, her mother was a prima ballerina and is now a yogi master.


title: Lena Hall

text: She has Filipino, Spanish, and Swedish ancestry through her father. Her paternal grandfather arrived from the Philippines to San Francisco in 1926, and her paternal grandmother is Swedish. Her sister is Calliope "Calli" Carvajal, a hair stylist.


title: Lena Hall

text: She is a graduate of Ruth Asawa San Francisco School of the Arts, where she first studied dance, and an alumna of the Young People's Teen Musical Theatre Company in San Francisco.


title: Lena Hall

text: Her first big break was singing for Pope John Paul II at Candlestick Park in San Francisco for over 50,000 people at the age of 7.


title: Lena Hall

text: Hall changed her professional name from "Celina Carvajal" to Lena Hall in 2013, saying she had created it for her music persona and now wanted to use it for her acting career as well. She explained her name change to "Broadway.com": "Multiple people in the industry suggested I have one name for everything. [Lena Hall] is just two shortenings of my first name and my last name. So Lena Hall "is" Celina Carvajal. It seemed like an easier way of people getting to know me. Lena Hall is a nice symmetrical name, and it reminds people of Lena Horne, who was a singer. And when people hear my name, I want them to think of a singer". She later found out that "Carvajal" is actually a stage name taken seven generations back that became a family name. Hall said that it was one of the reasons why she was able to let go of the Carvajal name because it was a stage name, and it felt like her ancestors would agree with her name change.


title: Lena Hall

text: Hall made her Broadway debut in 1999 in "Cats", taking over the role of Demeter after first performing in the national tour in 1998. She next took over the role of Ann "Anytime Annie" Reilly in "42nd Street". She also performed in a national tour of "Annie Get Your Gun", understudying the lead role.


title: Lena Hall

text: In 2003, Hall appeared in "Radiant Baby", a musical about artist Keith Haring, in various roles. In 2004 she was in the original ensemble of "Dracula, the Musical", and was the understudy for Kelli O'Hara as Lucy Westenra. In 2006 she was in the original ensemble of the musical "Tarzan", and was also the understudy for Jennifer Gambatese as Jane Porter.


title: Lena Hall

text: In 2008, she competed in the reality show "", in which she was the 3rd contestant eliminated, and starred in the Off-Broadway musicals "Green Eyes", and "Bedbugs!!!", in which she played the role of Carly at the New York Musical Theatre Festival.


title: Lena Hall

text: In 2009, she was the understudy for Leslie Kritzer in the role of Monica P. Miller in the musical "Rooms: A Rock Romance". Also in 2009, she took over the lead role of Sarah in the musical "The Toxic Avenger" at the New World Stages.


title: Lena Hall

text: In 2011, she performed as Daughter of the Ocean in the musical "Prometheus Bound", inspired by Aeschylus's Ancient Greek tragedy, at the American Repertory Theater, and also appeared as Blaze in the musical "Chix6". In 2013, Hall originated the role of Nicola (played on film by Jemima Rooper) in the musical "Kinky Boots", which won the Tony Award for Best Musical.


title: Lena Hall

text: In 2014, Hall was cast as Yitzhak in the Broadway production "Hedwig and the Angry Inch", (a role previously played off-Broadway by Miriam Shor) opposite Neil Patrick Harris, for which she won the Tony Award for Best Featured Actress in a Musical. She left the role on April 4, 2015, after playing Yitzhak opposite Harris, Darren Criss, Michael C. Hall, Andrew Rannells and John Cameron Mitchell as Hedwig. In 2016, she was cast in the national tour of Hedwig, which opened on October 2, 2016, reprising her role as Yitzhak, and for one performance a week, playing the title role of Hedwig for a total of eight performances in Los Angeles and San Francisco, making her the first actor to play both roles in the same production. She played the roles in San Francisco and Los Angeles alongside "Glee" star Darren Criss.


title: Lena Hall

text: Following her run in "Hedwig and the Angry Inch", Hall toured North America alongside Josh Groban on his "Stages" tour.


title: Lena Hall

text: On September 28, 2015, Hall released her first solo album, "Sin & Salvation: Live At the Carlyle", featuring her renditions of songs from artists such as Led Zeppelin, Tori Amos, Hozier, and James Brown. The album was recorded at the Carlyle Hotel during Hall's musical show "Sin & Salvation", which ran for two weeks.


title: Lena Hall

text: Her TV work include 9 episodes of "All My Children" in the role of Treena in 2009, Juicy Lucy in "Good Girls Revolt" (2015), the voice of Countess Coloratura/Rara in the 115th episode of "", titled "The Mane Attraction".


title: Lena Hall

text: In 2016, Hall played a seductive yoga instructor in an episode of the HBO series "Girls". She also performs the songs along with Tony Vincent for the fictional band "Dog Gone" in the 2015 PBS series "Nature Cat".


title: Lena Hall

text: She has appeared in five movies: "Sex and the City" (2008), "The Graduates" (2008), "Born from the Foot" (2009), "The Big Gay Musical" (2009), and "Becks" (2017), in which she plays the title role and her first leading role in a feature film, and received widespread critical acclaim for her performance. which won the U.S. Fiction Award at the LA Film Festival.


title: Lena Hall

text: In 2017, Hall starred in the role of Pip on Sarah Ruhl's Off-Broadway play "How to Transcend a Happy Marriage" starring opposite Marisa Tomei at the Lincoln Center.


title: Lena Hall

text: Hall released a series of 12 digital EPs titled "Obsessed" in 2018, one per month. The January release consists of selections from "Hedwig and the Angry Inch", while each of the others features her renditions of several songs by a different artist.


title: Lena Hall

text: In 2021, Hall voice acted in a live-streamed reading of a science fiction screenplay called "Aurora" by Joe Scott, playing multiple roles. The reading, which served as Scott's YouTube channel's Halloween special and centered around the Aurora, Texas, UFO incident, saw its proceeds donated to Team Seas.


title: Azeotrope

text: An azeotrope () or a constant heating point mixture is a mixture of two or more liquids whose proportions cannot be altered or changed by simple distillation. This happens when an azeotrope is boiled, the vapour has the same proportions of constituents as the unboiled mixture. Because their composition is unchanged by distillation, azeotropes are also called (especially in older texts) "constant boiling point mixtures".


title: Azeotrope

text: Some azeotropic mixtures of pairs of compounds are known, and many azeotropes of three or more compounds are also known. In such a case it is not possible to separate the components by fractional distillation and azeotropic distillation is usually used instead. There are two types of azeotropes: minimum boiling azeotrope and maximum boiling azeotrope. A solution that shows greater positive deviation from Raoult's law forms a minimum boiling azeotrope at a specific composition. For example, an ethanol–water mixture (obtained by fermentation of sugars) on fractional distillation yields a solution containing at most 95% (by volume) of ethanol. Once this composition has been achieved, the liquid and vapour have the same composition, and no further separation occurs.


title: Azeotrope

text: A solution that shows large negative deviation from Raoult's law forms a maximum boiling azeotrope at a specific composition. Nitric acid and water is an example of this class of azeotrope. This azeotrope has an approximate composition of 68% nitric acid and 32% water by mass, with a boiling point of .


title: Azeotrope

text: The term "azeotrope" is derived from the Greek words ζέειν (boil) and τρόπος (turning) with the prefix α- (no) to give the overall meaning, "no change on boiling". The term was coined in 1911 by English chemist John Wade and Richard William Merriman.


title: Azeotrope

text: Each azeotrope has a characteristic boiling point. The boiling point of an azeotrope is either less than the boiling point temperatures of any of its constituents (a positive azeotrope), or greater than the boiling point of any of its constituents (a negative azeotrope).


title: Azeotrope

text: Construction of the p-v-x diagram which shows azeotropic behavior is shown in the accompanying diagram


title: Azeotrope

text: A well-known example of a positive azeotrope is 95.63% ethanol and 4.37% water (by mass), which boils at 78.2 °C.


title: Azeotrope

text: Ethanol boils at 78.4 °C, water boils at 100 °C, but the azeotrope boils at 78.2 °C, which is lower than either of its constituents. Indeed, 78.2 °C is the minimum temperature at which any ethanol/water solution can boil at atmospheric pressure. In general, a positive azeotrope boils at a lower temperature than any other ratio of its constituents. Positive azeotropes are also called "minimum boiling mixtures" or "pressure maximum" azeotropes.


title: Azeotrope

text: In general, a negative azeotrope boils at a higher temperature than any other ratio of its constituents. Negative azeotropes are also called "maximum boiling mixtures" or "pressure minimum" azeotropes. An example of a negative azeotrope is hydrochloric acid at a concentration of 20.2% and 79.8% water (by mass). Hydrogen chloride boils at −84 °C and water at 100 °C, but the azeotrope boils at 110 °C, which is higher than either of its constituents. The maximum temperature at which any hydrochloric acid solution can boil is 110 °C. Other examples:


title: Azeotrope

text: If the constituents of a mixture are completely miscible in all proportions with each other, the type of azeotrope is called a "homogeneous azeotrope". For example, any amount of ethanol can be mixed with any amount of water to form a homogeneous solution.


title: Azeotrope

text: If the constituents are not completely miscible, an azeotrope can be found inside the miscibility gap. This type of azeotrope is called "heterogeneous azeotrope" or heteroazeotrope. A heteroazeotropic distillation will have two liquid phases. For example, acetone / methanol / chloroform form an intermediate boiling (saddle) azeotrope.


title: Azeotrope

text: For example, if equal volumes of chloroform (water solubility 0.8 g/100 ml at 20 °C) and water are shaken together and then left to stand, the liquid will separate into two layers. Analysis of the layers shows that the top layer is mostly water with a small amount of chloroform dissolved in it, and the bottom layer is mostly chloroform with a small amount of water dissolved in it. If the two layers are heated together, the system of layers will boil at 53.3 °C, which is lower than either the boiling point of chloroform (61.2 °C) or the boiling point of water (100 °C). The vapor will consist of 97.0% chloroform and 3.0% water regardless of how much of each liquid layer is present provided both layers are indeed present. If the vapor is re-condensed, the layers will reform in the condensate, and will do so in a fixed ratio, which in this case is 4.4% of the volume in the top layer and 95.6% in the bottom layer.


title: Azeotrope

text: Azeotropes consisting of two constituents are called "binary" azeotropes such as diethyl ether (33%) / halothane (66%) a mixture once commonly used in anesthesia. For example, benzene and hexafluorobenzene form a double binary azeotrope.


title: Azeotrope

text: Azeotropes consisting of three constituents are called "ternary" azeotropes, e.g. acetone / methanol / chloroform. Azeotropes of more than three constituents are also known.


title: Azeotrope

text: Combinations of solvents that do not form an azeotrope when mixed in any proportion are said to be zeotropic. Azeotropes are useful in separating zeotropic mixtures. An example is acetic acid and water, which do not form an azeotrope. Despite this, it is very difficult to separate pure acetic acid (boiling point: 118.1 °C) from a solution of acetic acid and water by distillation alone. As progressive distillations produce solutions with less and less water, each further distillation becomes less effective at removing the remaining water. Distilling the solution to dry acetic acid is therefore economically impractical. But ethyl acetate forms an azeotrope with water that boils at 70.4 °C. By adding ethyl acetate as an entrainer, it is possible to distill away the azeotrope and leave nearly pure acetic acid as the residue.


title: Azeotrope

text: The condition relates activity coefficients in liquid phase to total pressure and the vapour pressures of pure components.


title: Azeotrope

text: Azeotropes can form only when a mixture deviates from Raoult's law, the equality of compositions in liquid phase and vapor phases, in vapour-liquid equilibrium and Dalton's law the equality of pressures for total pressure being equal to the sum of the partial pressures in real mixtures.


title: Azeotrope

text: In other words: Raoult's law predicts the vapor pressures of ideal mixtures as a function of composition ratio. More simply: per Raoult's law molecules of the constituents stick to each other to the same degree as they do to themselves. For example, if the constituents are X and Y, then X sticks to Y with roughly equal energy as X does with X and Y does with Y. A so-called "positive deviation" from Raoult's law results when the constituents have a disaffinity for each other – that is X sticks to X and Y to Y better than X sticks to Y. Because this results in the mixture having less total affinity of the molecules than the pure constituents, they more readily escape from the stuck-together phase, which is to say the liquid phase, and into the vapor phase. When X sticks to Y more aggressively than X does to X and Y does to Y, the result is a "negative deviation" from Raoult's law. In this case because the molecules in the mixture are sticking together more than in the pure constituents, they are more reluctant to escape the stuck-together liquid phase.


title: Azeotrope

text: When the deviation is great enough to cause a maximum or minimum in the vapor pressure versus composition function, it is a mathematical consequence that at that point, the vapor will have the same composition as the liquid, resulting in an azeotrope.


title: Azeotrope

text: The adjacent diagram illustrates total vapor pressure of three hypothetical mixtures of constituents, X, and Y. The temperature throughout the plot is assumed to be constant.


title: Azeotrope

text: The center trace is a straight line, which is what Raoult's law predicts for an ideal mixture. In general solely mixtures of chemically similar solvents, such as "n"-hexane with "n"-heptane, form nearly ideal mixtures that come close to obeying Raoult's law.


title: Azeotrope

text: The top trace illustrates a nonideal mixture that has a positive deviation from Raoult's law, where the total combined vapor pressure of constituents, X and Y, is greater than what is predicted by Raoult's law. The top trace deviates sufficiently that there is a point on the curve where its tangent is horizontal. Whenever a mixture has a positive deviation and has a point at which the tangent is horizontal, the composition at that point is a positive azeotrope. At that point the total vapor pressure is at a maximum. Likewise the bottom trace illustrates a nonideal mixture that has a negative deviation from Raoult's law, and at the composition where tangent to the trace is horizontal there is a negative azeotrope. This is also the point where total vapor pressure is minimum.


title: Azeotrope

text: The boiling and recondensation of a mixture of two solvents are changes of chemical state; as such, they are best illustrated with a phase diagram. If the pressure is held constant, the two variable parameters are the temperature and the composition.


title: Azeotrope

text: The phase diagram on the right shows a "positive" azeotrope of hypothetical constituents, X and Y. The bottom trace illustrates the boiling temperature of various compositions. Below the bottom trace, only the liquid phase is in equilibrium. The top trace illustrates the vapor composition above the liquid at a given temperature. Above the top trace, only the vapor is in equilibrium. Between the two traces, liquid and vapor phases exist simultaneously in equilibrium: for example, heating a 25% X : 75% Y mixture to temperature AB would generate vapor of composition B over liquid of composition A. The azeotrope is the point on the diagram where the two curves touch. The horizontal and vertical steps show the path of repeated distillations. Point A is the boiling point of a nonazeotropic mixture. The vapor that separates at that temperature has composition B. The shape of the curves requires that the vapor at B be richer in constituent X than the liquid at point A. The vapor is physically separated from the VLE (vapor-liquid equilibrium) system and is cooled to point C, where it condenses. The resulting liquid (point C) is now richer in X than it was at point A. If the collected liquid is boiled again, it progresses to point D, and so on. The stepwise progression shows how repeated distillation can never produce a distillate that is richer in constituent X than the azeotrope. Note that starting to the right of the azeotrope point results in the same stepwise process closing in on the azeotrope point from the other direction.


title: Azeotrope

text: The phase diagram on the right shows a "negative" azeotrope of ideal constituents, X and Y. Again the bottom trace illustrates the boiling temperature at various compositions, and again, below the bottom trace the mixture must be entirely liquid phase. The top trace again illustrates the condensation temperature of various compositions, and again, above the top trace the mixture must be entirely vapor phase. The point, A, shown here is a boiling point with a composition chosen very near to the azeotrope. The vapor is collected at the same temperature at point B. That vapor is cooled, condensed, and collected at point C. Because this example is a negative azeotrope rather than a positive one, the distillate is "farther" from the azeotrope than the original liquid mixture at point A was. So the distillate is poorer in constituent X and richer in constituent Y than the original mixture. Because this process has removed a greater fraction of Y from the liquid than it had originally, the residue must be poorer in Y and richer in X after distillation than before.


title: Azeotrope

text: If the point, A had been chosen to the right of the azeotrope rather than to the left, the distillate at point C would be farther to the right than A, which is to say that the distillate would be richer in X and poorer in Y than the original mixture. So in this case too, the distillate moves away from the azeotrope and the residue moves toward it. This is characteristic of negative azeotropes. No amount of distillation, however, can make either the distillate or the residue arrive on the opposite side of the azeotrope from the original mixture. This is characteristic of "all" azeotropes.


title: Azeotrope

text: The traces in the phase diagrams separate whenever the composition of the vapor differs from the composition of the liquid at the same temperature. Suppose the total composition were 50/50%. You could make this composition using 50% of 50/50% vapor and 50% of 50/50% liquid, but you could also make it from 83.33% of 45/55% vapor and 16.67% of 75%/25% liquid, as well as from many other combinations. The separation of the two traces represents the range of combinations of liquid and vapor that can make each total composition.


title: Azeotrope

text: For both the top and bottom traces, the temperature point of the azeotrope is the constant temperature chosen for the graph. If the ambient pressure is controlled to be equal to the total vapor pressure at the azeotropic mixture, then the mixture will boil at this fixed temperature.


title: Azeotrope

text: Vapor pressure of both pure liquids as well as mixtures is a sensitive function of temperature. As a rule, vapor pressure of a liquid increases nearly exponentially as a function of temperature. If the graph were replotted for a different fixed temperature, then the total vapor pressure at the azeotropic composition will certainly change, but it is also possible that the composition at which the azeotrope occurs will change. This implies that the composition of an azeotrope is affected by the pressure chosen at which to boil the mixture. Ordinarily distillation is done at atmospheric pressure, but with proper equipment it is possible to carry out distillation at a wide variety of pressures, both above and below atmospheric pressure.


title: Azeotrope

text: If the two solvents can form a negative azeotrope, then distillation of any mixture of those constituents will result in the residue being closer to the composition at the azeotrope than the original mixture.


title: Azeotrope

text: For example, if a hydrochloric acid solution contains less than 20.2% hydrogen chloride, boiling the mixture will leave behind a solution that is richer in hydrogen chloride than the original. If the solution initially contains more than 20.2% hydrogen chloride, then boiling will leave behind a solution that is poorer in hydrogen chloride than the original. Boiling of any hydrochloric acid solution long enough will cause the solution left behind to approach the azeotropic ratio. On the other hand, if two solvents can form a positive azeotrope, then distillation of any mixture of those constituents will result in the residue away from the composition at the azeotrope than the original mixture. For example, if a 50/50 mixture of ethanol and water is distilled once, the distillate will be 80% ethanol and 20% water, which is closer to the azeotropic mixture than the original, which means the solution left behind will be poorer in ethanol. Distilling the 80/20% mixture produces a distillate that is 87% ethanol and 13% water. Further repeated distillations will produce mixtures that are progressively closer to the azeotropic ratio of 95.5/4.5%. No numbers of distillations will ever result in a distillate that exceeds the azeotropic ratio. Likewise, when distilling a mixture of ethanol and water that is richer in ethanol than the azeotrope, the distillate (contrary to intuition) will be poorer in ethanol than the original but still richer than the azeotrope.


title: Azeotrope

text: Distillation is one of the primary tools that chemists and chemical engineers use to separate mixtures into their constituents. Because distillation cannot separate the constituents of an azeotrope, the separation of azeotropic mixtures (also called "azeotrope breaking") is a topic of considerable interest. Indeed, this difficulty led some early investigators to believe that azeotropes were actually compounds of their constituents. But there are two reasons for believing that this is not the case. One is that the molar ratio of the constituents of an azeotrope is not generally the ratio of small integers. For example, the azeotrope formed by water and acetonitrile contains 2.253 moles (or 9/4 with a relative error of just 2%) of acetonitrile for each mole of water. A more compelling reason for believing that azeotropes are not compounds is, as discussed in the last section, that the composition of an azeotrope can be affected by pressure. Contrast that with a true compound, carbon dioxide for example, which is two moles of oxygen for each mole of carbon no matter what pressure the gas is observed at. That azeotropic composition can be affected by pressure suggests a means by which such a mixture can be separated.


title: Azeotrope

text: A hypothetical azeotrope of constituents X and Y is shown in the adjacent diagram. Two sets of curves on a phase diagram one at an arbitrarily chosen low pressure and another at an arbitrarily chosen, but higher, pressure. The composition of the azeotrope is substantially different between the high- and low-pressure plots – higher in X for the high-pressure system. The goal is to separate X in as high a concentration as possible starting from point A. At the low pressure, it is possible by progressive distillation to reach a distillate at the point, B, which is on the same side of the azeotrope as A. Note that successive distillation steps near the azeotropic composition exhibit very little difference in boiling temperature. If this distillate is now exposed to the high pressure, it boils at point C. From C, by progressive distillation it is possible to reach a distillate at the point D, which is on the same side of the high-pressure azeotrope as C. If that distillate is then exposed again to the low pressure, it boils at point E, which is on the "opposite" side of the low-pressure azeotrope to A. So, by means of the pressure swing, it is possible to cross over the low-pressure azeotrope.


title: Azeotrope

text: When the solution is boiled at point E, the distillate is poorer in X than the residue at point E. This means that the residue is richer in X than the distillate at point E. Indeed, progressive distillation can produce a residue as rich in X as is required.


title: Azeotrope

text: Note that both azeotropes above are of the "positive", or "minimum boiling" type; care must be taken to ensure that the correct component of the separation step is retained, i.e. the binary phase-envelope diagram (boiling-point curve) must be correctly read.


title: Azeotrope

text: A mixture of 5% water with 95% tetrahydrofuran is an example of an azeotrope that can be economically separated using a pressure swing – a swing in this case between 1 atm and 8 atm. By contrast the composition of the water to ethanol azeotrope discussed earlier is not affected enough by pressure to be easily separated using pressure swings and instead, an entrainer may be added that "either" modifies the azeotropic composition and exhibits immiscibility with one of the components, "or" extractive distillation may be used.


title: Azeotrope

text: Other methods of separation involve introducing an additional agent, called an "entrainer", that will affect the volatility of one of the azeotrope constituents more than another. When an entrainer is added to a binary azeotrope to form a ternary azeotrope, and the resulting mixture distilled, the method is called azeotropic distillation. The best known example is adding benzene or cyclohexane to the water/ethanol azeotrope. With cyclohexane as the entrainer, the ternary azeotrope is 7% water, 17% ethanol, and 76% cyclohexane, and boils at 62.1 °C. Just enough cyclohexane is added to the water/ethanol azeotrope to engage all of the water into the ternary azeotrope. When the mixture is then boiled, the azeotrope vaporizes leaving a residue composed almost entirely of the excess ethanol.


title: Azeotrope

text: Another type of entrainer is one that has a strong chemical affinity for one of the constituents. Using again the example of the water/ethanol azeotrope, the liquid can be shaken with calcium oxide, which reacts strongly with water to form the nonvolatile compound, calcium hydroxide. Nearly all of the calcium hydroxide can be separated by filtration and the filtrate redistilled to obtain 100% pure ethanol.


title: Azeotrope

text: A more extreme example is the azeotrope of 1.2% water with 98.8% diethyl ether. Ether holds the last bit of water so tenaciously that only a very powerful desiccant such as sodium metal added to the liquid phase can result in completely dry ether.


title: Azeotrope

text: Anhydrous calcium chloride is used as a desiccant for drying a wide variety of solvents since it is inexpensive and does not react with most nonaqueous solvents. Chloroform is an example of a solvent that can be effectively dried using calcium chloride.


title: Azeotrope

text: When a salt is dissolved in a solvent, it always has the effect of raising the boiling point of that solvent – that is it decreases the volatility of the solvent. When the salt is readily soluble in one constituent of a mixture but not in another, the volatility of the constituent in which it is soluble is decreased and the other constituent is unaffected. In this way, for example, it is possible to break the water/ethanol azeotrope by dissolving potassium acetate in it and distilling the result.


title: Azeotrope

text: Extractive distillation is similar to azeotropic distillation, except in this case the entrainer is less volatile than any of the azeotrope's constituents. For example, the azeotrope of 20% acetone with 80% chloroform can be broken by adding water and distilling the result. The water forms a separate layer in which the acetone preferentially dissolves. The result is that the distillate is richer in chloroform than the original azeotrope.


title: Azeotrope

text: The pervaporation method uses a membrane that is more permeable to the one constituent than to another to separate the constituents of an azeotrope as it passes from liquid to vapor phase. The membrane is rigged to lie between the liquid and vapor phases. Another membrane method is vapor permeation, where the constituents pass through the membrane entirely in the vapor phase. In all membrane methods, the membrane separates the fluid passing through it into a permeate (that which passes through) and a retentate (that which is left behind). When the membrane is chosen so that is it more permeable to one constituent than another, then the permeate will be richer in that first constituent than the retentate.


title: Azeotrope

text: The rules for positive and negative azeotropes apply to all the examples discussed so far, but there are some examples that don't fit into the categories of positive or negative azeotropes. The best known of these is the ternary azeotrope formed by 30% acetone, 47% chloroform, and 23% methanol, which boils at 57.5 °C. Each pair of these constituents forms a binary azeotrope, but chloroform/methanol and acetone/methanol both form positive azeotropes while chloroform/acetone forms a negative azeotrope. The resulting ternary azeotrope is neither positive nor negative. Its boiling point falls "between" the boiling points of acetone and chloroform, so it is neither a maximum nor a minimum boiling point. This type of system is called a saddle azeotrope. Only systems of three or more constituents can form saddle azeotropes.


title: Azeotrope

text: A rare type of complex binary azeotrope is one where the boiling point and condensation point curves touch at two points in the phase diagram. Such a system is called a double azeotrope, and will have two azeotropic compositions and boiling points. An example is water and "N"-methylethylenediamine.


title: Richard Harmon

text: Richard Scott Harmon is a Canadian actor. His roles on television include John Murphy in The CW's "The 100", Jasper Ames in "The Killing" and Julian Randol on "Continuum". Harmon received critical praise for his role in the movie "If I Had Wings".


title: Richard Harmon

text: Richard Harmon was born in Mississauga, Ontario, Canada. His parents are director Allan Harmon and producer Cynde Harmon; his sister is actress Jessica Harmon. After that, Richard Harmon and his family relocated to Vancouver, where he attended Sentinel Secondary School. In high school, he was incredibly passionate about acting.


title: Caroline in the City

text: Caroline in the City is an American television sitcom that ran on the NBC television network from 1995 until 1999. It stars Lea Thompson as cartoonist Caroline Duffy, who lives in Manhattan. The series premiered on September 21, 1995, in the "Must See TV" Thursday night block between "Seinfeld" and "ER". The show ran for 97 episodes over four seasons before it was cancelled; the final episode, which ended on a cliffhanger that was never resolved, was broadcast on April 26, 1999. The series' rights are currently held by CBS Television Distribution (now known as CBS Media Ventures).


title: Caroline in the City

text: Caroline Duffy (Lea Thompson), a cartoonist who lives in Manhattan, spends a lot of time with dates and lovers, and meddles in the lives of her friends and neighbors. In the pilot episode, she has broken up with Del Cassidy (Eric Lutes), who quickly finds another date. She hires Richard Karinsky (Malcolm Gets) to be her new colorist, and he pretends to be her new boyfriend during a dinner to prevent her from being embarrassed over Del's moving on. During the first season, Richard develops feelings for Caroline.


title: Caroline in the City

text: Caroline's success as a cartoonist is displayed throughout the ; her cartoon character gets a balloon in the Macy's Thanksgiving Day Parade, she has a park dedicated to her in her native Peshtigo, Wisconsin, and she even has an offer for a cereal brand. When she was a child, she drew violent pictures of her brother Chris, and after dropping out of college, she started doodling at a copywriting job. It took less than five years for her cartoon to become nationally syndicated, and she even appeared on "The Today Show".


title: Caroline in the City

text: Towards the end of season one, Del proposes to Caroline. Richard is distressed by this, and searches for a new job. Although Richard has kept his feelings secret, their friends Annie (Amy Pietz) and Remo (Tom La Grua) figure out that he loves Caroline. The day before the wedding, Richard writes her a love letter where he asks Caroline to meet him at Remo's if she loves him. He leaves the letter in a pile of wedding thank-you cards. Caroline arrives at Remo's but does not mention the letter, and continues with the wedding plans. Richard decides to leave Manhattan. When Caroline and Del call off the wedding, Caroline visits Richard's apartment but he has left.


title: Caroline in the City

text: In the , Richard returns to Manhattan after having been in Paris where he had tried to sell paintings. Caroline gives the thank-you cards to a friend; Richard tries to find and destroy the love letter; he tosses it out of the window, only to have Annie find it. He resumes his old job as Caroline's colorist. Later, Caroline discovers that she has feelings for Richard; however, Richard has reunited with his former girlfriend Julia, whom he met in Manhattan. Caroline leaves a message on his answering machine telling him that she loves him, but Julia discovers it and erases it.


title: Caroline in the City

text: Richard and Julia get married which prompts a bitter love triangle among the three. Richard eventually splits with Julia.


title: Caroline in the City

text: Caroline and Richard eventually become a couple. However, they split after arguing over whether to have children; Richard learned that Julia had a child. In the final episode, which ends on an unresolved cliffhanger, Annie and Del are now in a new relationship, while Caroline is about to marry another man - her childhood friend Randy - when Richard shows up at the wedding.


title: Caroline in the City

text: This is a list of the notable guest stars in the series. Some of them appear as their characters from related NBC series that aired around the same time.


title: Caroline in the City

text: Bonnie Timmons drew the illustrations and animations that are supposed to represent Caroline's eponymous in-show comic strip.


title: Caroline in the City

text: Though not officially a companion show to "Cheers," "Wings," and "Frasier", "Caroline in the City" exists in the same universe as those shows, with several crossovers and connections with "Frasier" in particular. Not only does the end of one early Season 1 episode feature "Frasier" characters, Daphne and Niles, in Frasier's apartment (filmed on "Frasier"'s set and guest-starring Jane Leeves and David Hyde Pierce as their characters) looking at a "Caroline in the City" cartoon, but lead Eric Lutes played Frasier's boss Tom Duran in two episodes. David Hyde Pierce also appears a second time as another character, this time playing an IRS man who dreams of being in "Cats" Dan Butler (Bulldog in "Frasier") had a recurring role as a museum owner, plus "Frasier" actors Harriet Sansom Harris (Bebe) and Edward Hibbert (Gil) appear in the same Season 3 episode as each other, playing different characters (and not sharing any scenes). Additionally, Scott Atkinson (who portrayed Daphne's ex-boyfriend, Clive, in a "Frasier" episode) also appears playing Caroline's love interest in one episode.


title: Caroline in the City

text: Matthew Perry appears as his "Friends" character Chandler Bing (not named but implied to be him and advertised by the network as such in their crossover promotions) in the episode "Caroline and the Folks" in a crossover appearance in which Annie meets Chandler at the video store. The same night, Lea Thompson appeared as Caroline Duffy (also never named as such but implied to be - and advertised as - her character) in the November 2, 1995, "Friends" episode "The One with the Baby on the Bus".


title: Caroline in the City

text: In the same episode - "Caroline and the Folks" - which featured Chandler from "Friends", Jonathan Silverman also appeared, playing his character Jonathan Eliot (again not named but advertised as such) from the sitcom "The Single Guy".


title: Caroline in the City

text: CBS DVD (distributed by Paramount) released the first two seasons on DVD in Region 1 in 2008/2009. A decade later, the remaining two seasons were both released (though lacking episodes) in Region 1 on August 6, 2019.


title: Sola scriptura

text: , meaning by scripture alone, is a Christian theological doctrine held by most Protestant Christian denominations, in particular the Lutheran and Reformed traditions of Protestantism, that posits the Bible as the sole infallible source of authority for Christian faith and practice. The Catholic Church considers it heterodox and generally the Orthodox churches consider it to be contrary to the 'phronema' of the Church.


title: Sola scriptura

text: While the scriptures' meaning is mediated through many kinds of subordinate authority—such as the ordinary teaching offices of a church, the ecumenical creeds, councils of the Catholic Church, or even personal special revelation— in contrast rejects any infallible authority other than the Bible. In this view, all non-scriptural authority is derived from the authority of the scriptures or is independent of the scriptures, and is, therefore, subject to reform when compared to the teaching of the Bible.