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Critical frequency

In telecommunication, the term critical frequency has the following meanings: In radio propagation by way of the ionosphere, the limiting frequency at or below which a wave component is reflected by, above which it penetrates through, an ionospheric layer. At near vertical incidence, the limiting frequency at or below which incidence, the wave component is reflected by, above which it penetrates through, an ionospheric layer. Critical Frequency changes with time of day, atmospheric conditions and angle of fire of the radio waves by antenna; the existence of the critical frequency is the result of electron limitation, i.e. the inadequacy of the existing number of free electrons to support reflection at higher frequencies. In signal processing the critical frequency it is another name for the Nyquist frequency. Critical frequency is the highest magnitude of frequency above which the waves penetrate the ionosphere and below which the waves are reflected back from the ionosphere, it is denoted by "fc".

Its value is not fixed and it depends upon the electron density of the ionosphere. Critical frequency can be computed with the electron density given by: f c = 9 N max where Nmax is maximum electron density per m3 and fc is in Hz. Critical frequency can be computed by: f c = M U F / s e c θ where MUF is maximum usable frequency and θ is the angle of incidence The dependence of critical frequency with respect with electron density can be related through plasma oscillation concept the'Cold' Electrons mechanism. Ω p e = n e e 2 m ∗ ε 0, Using the electron charge e = 1.602 ⋅ 10 − 19 C o u l o m b s, electron mass m ∗ = 9.10938356 ⋅ 10 − 31 k i l o g r a m s and permittivity of free space ϵ o = 8.854187817 ⋅ 10 − 12 A 2 s 4 m − 3 k g − 1 gives, ω p e = 2 π f = 56.415 n e and solving for the frequency, f c = 8.979 N max ≈ 9 N max The index of refraction has the formula n = c v which shows dependence in wavelength. The result that the force due to the polarization field in an ionized gas of low concentration is canceled by the effect of collisions between ions and electrons is re‐established in a simple manner that displays the physical basis for the effect.

Because of this cancellation the Sellmeyer formula, determines the relation between the electron number density, N, the index of refraction, n, in the ionosphere when collisions are neglected. N 2 − 1 = − N e 2 ϵ o m ω 2. Using the default values for electron charge e, permittivity of free space and electron mass ϵ o, changing angular velocity ω with respect to frequency f this yields to n 2 − 1 = 3182.607 N 2 and solving for the refraction index n, n = 1 − 80.616 N f 2 ≈ 1 − 81 N f 2 All long-distance HF Radio Communications use HF Radio signals that are obliquely incident on the ionosphere, If the HF frequency is above Critical Frequency, the radio signals are passing through the ionosphere at an angle instead of head-on. The Critical Frequency is changing continuously and the F layer of the Ionosphere is responsible for the reflection of radio


Amapiano is a genre of electronic dance music that emerged in South Africa in 2016. It is distinguished by its elements of jazz and high pitched piano melodies, Kwaito basslines, low tempo 90s South African house rhythms and percussions from another local subgenre of house known as Bacardi. Although it is known the genre gained popularity in Gauteng, there is a lot of ambiguity in terms of where the Amapiano style of music originates, with various accounts of the musical style in Johannesburg townships, Alexandra and Katlehong where it is most common; because of the genre's similarities with Barcadi, some people assert the genre began in the Pretoria area with DJ Mjava, has been an on going debate about the origin of Amapiano. Various accounts as to who formed the popular genre make it impossible to pinpoint its origins. Amapiano was a confined success in the townships, playing in popular pubs and taverns around Gauteng; the sound itself was underground music, being shared around using messaging apps, more WhatsApp, before it became mainstream being recognised by streaming apps such as Deezer, Apple Music and Hiphopza.

The genre was further popularised by DJ's who would transform popular music hits and incorporating the jazzy low-tempo into those tracks, including DJ Ganyani, Sun-El Musician, DJ Maphorisa and Kabza De Small. Amapiano is getting more mainstream across Africa as of 2020, there are several dedicated charts now, more playlists on digital platforms not just by South Africans alone; the sound is filled with some melodious piano tunes coupled with gong gong sound making it up to what is called ”Amapiano”. Some DJ’s and producers do mix it up with Gqom. In January 2019, German-born American-based DJ Lars Behrenroth criticized the genre and its artists on Twitter. “Finally checked it out for the first time and all i can say is Amapiano & Godf#$! of Deep House = same WhatsApp group… what a snoozefest..eeeekkk”. The tweet caused a major uproar of many fans of the genre, his comment prompted several artists such as Black Coffee, Zakes Bantwini, Kid Fonque and Cassper Nyovest to defend the genre and laughed off Lars' criticism.

“I am a fan of Kwaito and Amapiano. I am not ashamed. I’m a House head but these genres are pure South African and need to be supported by every South African,” Prince Kaybee took to Twitter to slam Lars's comment and told him to "leave us and our music alone". South Africans shouldn’t let caucasian house music DJs talk bad about a proudly black pioneered sound like amapiano. Protect what's yours, with this mentality we are far from exporting music! These are black children trying to eat, bro. Let them shine! If you don’t like it shut up and move on, don’t say anything negative to try and slow down the growth of a proudly South African genre."


Snocross is a racing sport involving racing specialized high performance snowmobiles on natural or artificially-made tracks consisting of tight turns, banked corners, steep jumps and obstacles. Riders race at speed of up to 60 miles per hour. Jumps are up to 30 feet tall, so riders travel up to 130 feet before they touch the ground. According to the World Snowmobile Association which governs snocross and hillcross racing, snocross is the most popular form of snowmobile racing. Snocross was derived from the sport of motocross; the name is a portmanteau of the words "snowmobile" and "motocross". The sport uses a snowmobile instead of a motorcycle, a snow/ice surface instead of dirt; the snow/ice surface, either natural or man-made. Tracks are located in higher latitudes in the Northern Hemisphere since temperatures below freezing are required to maintain the frozen track surface. Motorcycle riders in motocross and supercross compete in snocross in the winter. Snocross became an event at the X Games in 1998.

X Games is a popular gathering place for some snow-related sports in the United States. The course at the first snocross event at the X Games resembled a motocross course, it had higher jumps that are now filled in with snow. The snowmobiles vary depending on their class. Sanctioning bodies are governed by International Snowmobile Racing rules. Drivers are required to wear a helmet with a minimum of 50% International Orange. Racing suit, goggles/eye protection, leather boots, shin guards, elbow pads, neck braces, knee guards, upper body protection (Motocross vests are NOT legal for Snocross. Hearing protection is required in non-stock classes. Races start with the drivers forming a line abreast at the start line; the event begins with either a drop of a green flag by the starter or by the starter turning on a light. Like other sports derived from cross country running, the winner is the rider who has the best holeshot; the event may be stopped for a dangerous condition. The snowmobiles are lined up for the restart by their position in the race, with the drivers involved in the stoppage starting in the rear.

The winner of the event is the rider. Events attract over 10,000 spectators. A snocross event uses the standard short-track motorsport standard of qualifying rounds, heat races, consolation final, the feature. X Games, Buttermilk Mountain in Aspen, Colorado Duluth Nationals, Minnesota. Held the weekend after Thanksgiving every year since its inception; the unofficial start to winter and the official kickoff to the Snocross racing season. Riders from New England and points beyond will join the ISOC teams in Duluth to get a jump on their own upcoming seasons. Snowcross World Cup Finals at Lugnet Riksskid Stadium in Falun, Sweden Grand Prix Ski-doo de Valcourt in Valcourt, Canada, in February. World Championship Snowmobile Derby at Eagle River, United States on the third weekend in January; the snocross track is quite small yet still exciting, is constructed inside the famed high-banked half-mile ice oval. The national sanctioning body for snowmobile snocross racing is International Series of Champions, owned by John Daniels.

ISOC sanctions the AMSOIL Championship Snocross Series national tour, along with regional series in Wisconsin and Michigan. ISOC replaced Joe Duncan's World PowerSports Association starting with the 2008-09 season; the ACS will consist of eight points-paying races in 2015–16, beginning with the AMSOIL Duluth National at Spirit Mountain on November 27–29. Highlights from ISOC's National events are televised on the CBS Sports Network. In the northeastern United States, Rock Maple Racing sanctioned snocross racing from the winter of 1991-92 until being sold in May 2010. New owners Eric Scott and Bob Roscoe chose to form the East Coast Snocross series to carry on the tradition RMR had created. Now owned by Mass. native Kurt Gagne, East Coast Snocross will sanction eight points-paying events in 2019, along with one ice drag event. Previous years have seen hillcross events sanctioned as well. Snowmobile racing is big in northern New England where snows are deep and temps remain cold for weeks at a time.

ECS races throughout New Hampshire, Massachusetts and New York. Mountain West Racing sanctions on eight events in northern Rocky Mountains states. There is a snocross track in Illinois, it is home to the Winter Thunder Challenge snocross club, an ISOC affiliate, they have to make snow to make up for the lack of natural snowfall. The Canadian Snowcross Racing Association hosts 5.5 regional & regional plus one additional national-only points-paying events across Ontario and Quebec. Owned by veteran promoter Ken Avann, the CSRA is Canada's national tour. Despite being an ISR affiliate, CSRA technical rules differ for various classes, making competition between series' on either side of the border challenging for riders and crew; the Quebec based SCMX series sanctions eight events across Quebec. The Ultimate Canadian Motorsports Association known as the North West Racing Association hosts 8 to 10 events in Central and Western Canada, with races held in the provinces of Alberta, Saskatchewan and north west Ontario.

The sport is popular in the Nordic c


Carioca is a demonym used to refer to anything related to the City of Rio de Janeiro as well as its eponymous State of Rio de Janeiro, in Brazil. The original word, "kara'i oka", comes from the indigenous Tupi language meaning "house of carijó", a native tribe of Rio de Janeiro who lived in the vicinity of the Carioca River, between the neighborhoods of Glória and Flamengo. Like other Brazilians, cariocas speak Portuguese; the carioca accent and sociolect are one of the most recognized in Brazil, in part because Rede Globo, the second-largest television network in the world, is headquartered in Rio de Janeiro. Thus, a lot of Brazilian TV programs, from news and documentary to entertainment, feature carioca-acting and -speaking talent; the archaic demonym for the Rio de Janeiro State is fluminense, taken from the Latin word flūmen, meaning "river." Despite the fact that carioca is a more ancient demonym of Rio de Janeiro's inhabitants, it was replaced by fluminense in 1783, when the latter was sanctioned as the official demonym of the Royal Captainship of Rio de Janeiro.

A few years after the City of São Sebastião do Rio de Janeiro had become the capital city of the Brazilian colonies. From 1783 and during all the Imperial Regime, carioca remained only as a nickname by which other Brazilians called the inhabitants of Rio. During the first years of the Brazilian Republic, carioca was the name given to those who lived in the slums or a pejorative way to refer to the bureaucratic elite of the Federal District. Only when the City of Rio lost its status as Federal District and became a Brazilian State, when the capital city was moved to Brasilia, was carioca made a co-official demonym with guanabarino. In 1975, the Guanabara State was eliminated by President Geisel, becoming the present-day City of Rio de Janeiro, carioca was made the demonym of its municipality. Despite the fact carioca is not recognized as an official demonym of Rio de Janeiro State, Brazilians call the inhabitants of Rio de Janeiro in general cariocas, most of its inhabitants claim to be cariocas.

Nowadays, social movements like "Somos Todos Cariocas" try to achieve the official recognition of carioca as a co-official demonym of the Rio de Janeiro State. Carioca people have invented a few sports. Cariocas are credited with creating the bossa nova style of music. Famous cariocas in film include "Brazilian bombshell" Carmen Miranda, a Portuguese woman who grew up in Rio de Janeiro. An eponymous song from 1933, has become a jazz standard. Carnaval Carioca is the Portuguese name for the Rio Carnival. Samba Carioca is a localized style of Brazilian Samba. There is an exercise drill used for dynamic stretching called Carioca, it consists of a repeating Samba dance step. The Portuguese spoken across the states of Rio de Janeiro and Espírito Santo and neighboring towns in Minas Gerais and in the city of Florianópolis, has similar features, hardly different from one another so cities such as Paraty, Campos dos Goytacazes, Cachoeiro de Itapemirim, Vila Velha and Linhares may be said to have the same dialect as Rio de Janeiro, as they are hardly perceived as strong regional variants by people from other parts of Brazil.

The Brazilian Portuguese variant spoken in the city of Rio de Janeiro is called carioca, it is called sotaque locally translated as "accent". It can be said that Rio de Janeiro presents a sociolect inside the major fluminense-capixaba dialect, as speakers inside the city may be recognizable more by their slang than the way the phonology of their speech, closer to the standard Brazilian Portuguese in the media than other variants, it is known for several distinctive traits new to either variant of the Portuguese language: Coda /s/ and /z/ can be pronounced as palato-alveolar and of English or the alveolo-palatal and of Catalan. That is inherited from European Portuguese, carioca shares it only with Florianopolitano and some other Fluminense accents. In the northern tones of Brazilian Portuguese, not all coda /s/ and /z/ become postalveolar. /ʁ/, as well what would be coda /ɾ/ in European Portuguese, may be realized as various voiceless and voiced guttural-like sounds, most the latter, many or most of them can be part of the phonetic repertory of a single speaker.

Among them the velar and uvular fricative pairs, as well both glottal transitions, the voiceless pharyngeal fricative and the uvular trill:, and. That diversity of allophones of a single rhotic phoneme is rare not just in Brazilian Portuguese but among most world languages; the consonants /t/ and /d/ before /i/ or final unstressed /ɛ ~ e/ become affricates and, respectively. From Tupi influence, through the Portuguese post-creole that appeared in southeastern Brazil after the ban of Língua Geral Paulista as a marker of Jesuit activity by the Marquis of Pombal, this is now common place in Brazilian Portuguese, as it spread with the bandeiras paulistas, expansion of mineiros to the Center-West and mass media, it is not as universal in São Paulo, Espírito Santo and southern Brazil though th

Lawrence Winters

Lawrence Winters, bass-baritone, was an African-American opera singer who had an active international career from the mid-1940s through the mid-1960s. He was part of the first generation of black opera singers to achieve wide success and is viewed as part of an instrumental group of performers who helped break down the barriers of racial prejudice in the opera world, he began his opera career at the New York City Opera in 1946 during a time when the NYCO was one of the few American opera companies hiring black artists. He sang a varied repertoire there through 1955, after which his career was based in Europe until his death at the age of fifty. Winters began to study singing in Salisbury, North Carolina, before entering Howard University in 1941, where he studied singing with Todd Duncan. After graduating from Howard in 1944 with a bachelor's degree in Music, he joined the Eva Jessye Choir. Shortly thereafter he sang the lead role in a concert production of Clarence Cameron White's Ouranga. Following this he became musical director in the Special Services Division at Fort Huachuca as a member of the U.

S. Armed Forces. After the end of World War II, Winters moved to New York City in 1946 where he was immediately engaged for the Broadway musical revue Call Me Mister, portraying a variety of smaller roles, his official recital debut followed in 1947 at Town Hall in New York. In 1948, he debuted as an opera singer in the New York City Opera in Verdi's Aida as Amonasro, he portrayed several more roles with the NYCO over the next seven years, including Dessalines in William Grant Still's Troubled Island, the four villains in Jacques Offenbach's The Tales of Hoffmann, Escamillo in Georges Bizet's Carmen, Tchelio in Sergei Prokofiev's The Love for Three Oranges, Tonio in Ruggero Leoncavallo's Pagliacci, Timur in Giacomo Puccini's Turandot, Alfio in Cavalleria rusticana, The Messenger in the world premiere of David Tamkin's The Dybbuk, the title role in Giuseppe Verdi's Rigoletto, King Balthazar in Gian Carlo Menotti's Amahl and the Night Visitors, Colline in Puccini's La bohème, the title role in Béla Bartók's Bluebeard's Castle, Count Almaviva in Mozart's The Marriage of Figaro, Joe in Show Boat, Germont in Verdi's La Traviata, Diomede in the New York premiere of William Walton's Troilus and Cressida among others.

While working with the NYCO, Winters toured as a concert artist and performed in operas with companies in Europe. In 1949 he came to Europe for the first time, drawing particular acclaim for a recital given in Berlin, he gave concert tours in Central America and in the United States Virgin Islands. In 1950 he joined the roster of principal baritones at the Royal Swedish Opera where he sang a number of roles for two seasons. In 1951, he sang the role of Porgy opposite Camilla Williams's Bess in the most complete recording of Gershwin's Porgy and Bess made up to that time, he made his debut with the Hamburg State Opera in 1952 reprising his role in Aida, returning there through 1957. He made his first appearance with the New York Philharmonic singing excerpts from operas in concert in 1957. In 1957 Winters became a principal baritone on the roster at the Deutsche Oper Berlin where he spent most of his time performing in operas through 1961, he sang in a number of roles with the Vienna State Opera and the San Francisco Opera during these years, including the title role in Carl Orff's Die Kluge, Fritz Kothner in Die Meistersinger von Nürnberg and Wolfram in Tannhäuser.

In February 1960 he returned to Broadway as Tyree Tucker in Ketti Frings's play The Long Dream. One of the few non-singing roles he portrayed during his career, Winters garnered a Tony Award nomination for his performance, he returned for one last performance at the NYCO in 1962. He returned to the Hamburg State Opera in 1961, working as a principal baritone with the company until his untimely death at the age of 50 in 1965. Winters is buried at the Ohlsdorf Cemetery. Lawrence Whisonant married Aida C. Bearden on June 9, 1943, in Manhattan, she was a first cousin of artist Romare Bearden, the son of journalist and civic activist Bessye J. Bearden. Aida's mother was Anna Elizabeth Miller. By way of her mother's first marriage to the Rev. Primus Priss Alston, Aida was a half-sister of the artist Charles Alston

Lord Lieutenant of Carlow

This is a list of people who have served as Lord Lieutenant of Carlow. There were lieutenants of counties in Ireland until the reign of James II, when they were renamed governors; the office of Lord Lieutenant was recreated on 23 August 1831. Sir Thomas Butler, 3rd Baronet 1699– Henry O'Brien, 8th Earl of Thomond 1714–1741 Sir Thomas Burdett, 1st Baronet, of Dunmore 1725–1727 William Burton 1741– Beauchamp Bagenal Clement Wolseley John Staunton Rochfort: 1779–1798 –1831 David La Touche: 1798–1816 William Browne: –1831 Henry Bruen: 1816–1831 The Lord Downes: 1820–1831 Thomas Kavanagh: –1831 The 4th Earl of Bessborough: 17 October 1831 – 1838 The 5th Earl of Bessborough: November 1838 – 28 January 1880 Arthur MacMorrough Kavanagh: 25 March 1880 – 25 December 1889 The 2nd Baron Rathdonnell: 26 February 1890 – 1922 Sainty, J. C. "Lieutenants and Lords-Lieutenants 1831-2005". Retrieved 2008-06-07