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Self-synchronizing code

In coding theory in telecommunications, a self-synchronizing code is a uniquely decodable code in which the symbol stream formed by a portion of one code word, or by the overlapped portion of any two adjacent code words, is not a valid code word. Put another way, a set of strings over an alphabet is called a self-synchronizing code if for each string obtained by concatenating two code words, the substring starting at the second symbol and ending at the second-last symbol does not contain any code word as substring; every self-synchronizing code is a prefix code. Other terms for self-synchronizing code are synchronized code or, comma-free code. A self-synchronizing code permits the proper framing of transmitted code words provided that no uncorrected errors occur in the symbol stream. Self-synchronizing codes allow recovery from uncorrected errors in the stream. Importance of self-synchronizing codes is not limited to data transmission. Self-synchronization facilitates some cases of data recovery, for example of a digitally encoded text.

The prefix code is self-synchronizing because 0, 1, 01 and 10 are not codes. High-Level Data Link Control Advanced Data Communication Control Procedures Fibonacci codingCounterexamples: The prefix code is not self-synchronizing because abab contains ba; the prefix code b∗a is not self-synchronizing because code word ba contains code word a. In UTF-8, bit patterns 0xxxxxxx and 11xxxxxx are used to mark the beginning of the next valid character Bit slip Comma code Self-clocking signal Berstel, Jean. Codes and automata. Encyclopedia of Mathematics and its Applications. 129. Cambridge: Cambridge University Press. ISBN 978-0-521-88831-8. Zbl 1187.94001. This article incorporates public domain material from the General Services Administration document: "Federal Standard 1037C"

Elliana Walmsley

Elliana Kathryn Walmsley is an American dancer. She became known for appearing in Lifetime's reality show Dance Moms, she is on tour with 24/7 dance conventions and JUMP conventions. Elliana was born in Colorado, she studied at Master Ballet Academy in Arizona. In 2016 she joined the US reality TV show Dance Moms, alongside her mother, during Season 6, she became a permanent member of the cast during Season 7 in 2017, before leaving at the end of that year. She returned for some episodes in season 8. In 2017, she participated in a national tour with castmate Maesi Caes to teach dance masterclasses and give solo performances. At the end of 2017, Walmsley originated the lead role of Grace in the musical Dance Divas Nutcracker, based on Cheryl Burke's book series: Dance Divas, it was performed off-Broadway from December 13 to December 17 at Theatre Row, New York City, where a portion of the money made went towards the charity "Dancers with Cancer". She has garnered a social media following, with 1 million followers on Instagram and 72,000 YouTube subscribers.

In July 2017, she competed at the annual national dance competition The Dance Awards, held in Orlando, Florida. She finished in the top ten in the Mini Female Best Dancer category. In July 2018, representing the Michelle Latimer Dance Academy, Walmsley won the title of Mini Female Best Dancer at The Dance Awards in Las Vegas, Nevada. In 2018, she participated in Dancing with the Stars: Juniors as a professional. In July 2019, she booked the starring role of Clara in the 2019/2020 Radio City Christmas Spectacular show alongside The Rockettes after pursuing the role for three years. Walmsley owns her own YouTube channel and has appeared in many YouTube videos on other channels, she has been photographed by Jordan Matter on his channel numerous times

Immaculate Conception Cathedral, Dili

The Immaculate Conception Metropolitan Cathedral in Dili is the main church of the Roman Catholic Archdiocese of Dili, East Timor. Plans to build the cathedral began in 1984 with the Indonesian Government providing funding totalling about US$235,000; the cathedral, situated on a 10,000-square-meter plot, measures 1,800 square meters and can hold 2,000 people. Indonesian President Soeharto on 2 November 1988 inaugurated Dili's new Catholic cathedral the largest in Southeast Asia; the ceremony was attended by Bishop Carlos Filipe Ximenes Belo. In October 1989 it was blessed by Pope John Paul II; the cathedral played an important part in the country’s independence struggle, with leaders like the Noble Laureate Bishop Belo advising people to go into the country’s election with the spirit of humility of Jesus Christ. The Church of San Antonio de Motael was the pro-cathedral of Dili before the cathedral was constructed. On 1 March 2007 the country's new Apostolic Nuncio, Archbishop Leopoldo Girelli, celebrated Mass at the Cathedral and visited camps for displaced people in and around the capital, the Seminary of Our Lady of Fatima.

On 27 April 2002 around 2,000 people gathered at the Cathedral for the arrival from Portugal of a statue of Our Lady of Fatima, to go on tour for three weeks as part of the celebrations ahead of the country’s independence. Mary, Our Lady of Fatima is the Patroness of East Timor. Among those welcoming the statue were Bishop Carlos Filipe Ximenes Belo, Bishop Basilio do Nascimento and other religious representatives; the two Catholic bishops of East Timor and the papal nuncio to the country have jointly urged people to end a prolonged spate of violence and pray for national reconciliation and peace, after Mass on 4 March 2007 at Immaculate Conception Cathedral. Father Jose Maia was the parish priest of Immaculate Conception Cathedral in 2009

Kurt Waldheim

Kurt Josef Waldheim was an Austrian diplomat and politician. Waldheim was the fourth Secretary-General of the United Nations from 1972 to 1981, President of Austria from 1986 to 1992. While he was running for the latter office in the 1986 election, the revelation of his service in Thessaloniki, Greece and in Yugoslavia, as an intelligence officer in Nazi Germany's Wehrmacht during World War II raised international controversy. Waldheim was born in Sankt Andrä-Wördern, near Vienna, on 21 December 1918, his father was a Roman Catholic school inspector of Czech origin named Watzlawick who changed his name that year as the Habsburg monarchy collapsed. Waldheim served in the Austrian Army and attended the Vienna Consular Academy, where he graduated in 1939. Waldheim's father was active in the Christian Social Party. Waldheim himself was politically unaffiliated during these years at the Academy. Three weeks after the German annexation of Austria in 1938, Waldheim applied for membership in the National Socialist German Students' League, a division of the Nazi Party.

Shortly thereafter he became a registered member of the mounted corps of the SA. On 19 August 1944, he married Elisabeth Ritschel in Vienna. A son and another daughter, followed. In early 1941, Waldheim was drafted into the Wehrmacht and posted to the Eastern Front where he served as a squad leader. In December, he was wounded but returned to service in 1942, his service in the Wehrmacht from 1942 to 1945 was the subject of international review in 1985 and 1986. In his 1985 autobiography, he stated that he was discharged from further service at the front and, for the remainder of the war, finished his law degree at the University of Vienna, in addition to marrying in 1944. After publication and witnesses came to light that revealed Waldheim’s military service continued until 1945, during which time he rose to the rank of Oberleutnant. Waldheim's functions within the staff of German Army Group E from 1942 until 1945, as determined by the International Commission of Historians, were: Interpreter and liaison officer with the 5th Alpine Division in Pljevlja from 22 March 1942 to July 1942.

O2 to the 1b with Kampfgruppe West in Bosnia in June/August 1942, Interpreter with the liaison staff attached to the Italian 9th Army in Tirana in early summer 1942, O1 to the 1a in the German liaison staff with the Italian 11th Army and in the staff of the Army Group South in Greece in July/October 1943, O3 to the 1c officer on the staff of Army Group E in Arksali, Kosovska Mitrovica and Sarajevo from October 1943 to January/February 1945. By 1943, Waldheim was serving in the capacity of an aide-de-camp in Army Group E, headed by General Alexander Löhr. In 1986, Waldheim said that he had served only as an interpreter and a clerk and had no knowledge either of reprisals against local Serb civilians or of massacres in neighboring provinces of Yugoslavia, he said that he had known about some of the things that had happened, had been horrified, but could not see what else he could have done. Much historical interest has centred on Waldheim's role in Operation Kozara in 1942. According to one post-war investigator, prisoners were shot within only a few hundred meters of Waldheim's office, 35 kilometres away at the Jasenovac concentration camp.

Waldheim stated that "he did not know about the murder of civilians there". Waldheim's name appears on the Wehrmacht's "honour list" of those responsible for the militarily successful operation; the Nazi puppet state, the Independent State of Croatia, awarded Waldheim the Medal of the Crown of King Zvonimir in silver with an oak branches cluster. Decades during the lobbying for his election as U. N. Secretary General, Yugoslav President Josip Broz Tito, who had led anti-German forces during the war, awarded Waldheim one of the highest Yugoslav orders, not knowing of his prior military service. Waldheim denied that he knew war crimes were taking place in Bosnia at the height of the battles between the Nazis and Tito's partisans in 1943. According to Eli Rosenbaum, in 1944, Waldheim reviewed and approved a packet of anti-Semitic propaganda leaflets to be dropped behind Soviet lines, one of which ended: "Enough of the Jewish war, kill the Jews, come over." In 1945, Waldheim surrendered to British forces in Carinthia, at which point he said he had fled his command post within Army Group E, where he was serving with General Löhr, seeking a special deal with the British.

Waldheim joined the Austrian diplomatic service in 1945, after finishing his studies in law at the University of Vienna. He served as First Secretary of the Legation in Paris from 1948, in the Ministry for Foreign Affairs in Vienna from 1951 to 1956. In 1956 he was made Ambassador to Canada, returning to the Ministry in 1960, after which he became the Permanent Representative of Austria to the United Nations in 1964. For two years beginning in 1968, he was the Federal Minister for Foreign Affairs for the Austrian People's Party, before going back as Permanent Representative to the U. N. in 1970. Shortly afterwards, he was defeated in the 1971 Austrian presidential elections. After losing the presidential election, Waldheim ran for Secretary-General of the United Nations in the 1971 selection. Waldheim was led the first two rounds of voting. However, he was opposed by China, the United Kingdom, the United States. Waldheim won an accidenta

Poynting–Robertson effect

The Poynting–Robertson effect known as Poynting–Robertson drag, named after John Henry Poynting and Howard P. Robertson, is a process by which solar radiation causes a dust grain orbiting a star to lose angular momentum relative to its orbit around the star; this is related to radiation pressure tangential to the grain's motion. This causes dust, small enough to be affected by this drag, but too large to be blown away from the star by radiation pressure, to spiral into the star. In the case of the Solar System, this can be thought of as affecting dust grains from 1 μm to 1 mm in diameter. Larger dust is to collide with another object long before such drag can have an effect. Poynting gave a description of the effect in 1903 based on the luminiferous aether theory, superseded by the theories of relativity in 1905–1915. In 1937 Robertson described the effect in terms of general relativity. Robertson considered dust motion in a beam of radiation emanating from a point source. A. W. Guess considered the problem for a spherical source of radiation and found that for particles far from the source the resultant forces are in agreement with those concluded by Poynting.

The effect can be understood depending on the reference frame chosen. From the perspective of the grain of dust circling a star, the star's radiation appears to be coming from a forward direction; therefore the absorption of this radiation leads to a force with a component against the direction of movement. The angle of aberration is small since the radiation is moving at the speed of light while the dust grain is moving many orders of magnitude slower than that. From the perspective of the star, the dust grain absorbs sunlight in a radial direction, thus the grain's angular momentum is not affected by it, but the re-emission of photons, isotropic in the frame of the grain, is no longer isotropic in the frame of the star. This anisotropic emission causes the photons to carry away angular momentum from the dust grain; the Poynting–Robertson drag can be understood as an effective force opposite the direction of the dust grain's orbital motion, leading to a drop in the grain's angular momentum. While the dust grain thus spirals into the star, its orbital speed increases continuously.

The Poynting–Robertson force is equal to: F P R = v c 2 W = r 2 L s 4 c 2 G M s R 5 where v is the grain's velocity, c is the speed of light, W is the power of the incoming radiation, r the grain's radius, G is the universal gravitational constant, Ms the Sun's mass, Ls is the solar luminosity and R the grain's orbital radius. The Poynting–Robertson effect is more pronounced for smaller objects. Gravitational force varies with mass, ∝ r 3, while the power it receives and radiates varies with surface area. So for large objects the effect is negligible; the effect is stronger closer to the sun. Gravity varies as 1 R 2 whereas the Poynting–Robertson force varies as 1 R 2.5, so the effect gets stronger as the object approaches the Sun. This tends to reduce the eccentricity of the object's orbit in addition to dragging it in. In addition, as the size of the particle increases, the surface temperature is no longer constant, the radiation pressure is no longer isotropic in the particle's reference frame.

If the particle rotates the radiation pressure may contribute to the change in angular momentum, either positively or negatively. Radiation pressure affects the effective force of gravity on the particle: it is felt more by smaller particles, blows small particles away from the Sun, it is characterized by the dimensionless dust parameter β, the ratio of the force due to radiation pressure to the force of gravity on the particle: β = F r F g = 3 L Q P R 16 π G M c ρ s where Q P R is the Mie scattering coefficient, ρ is the density and s is the size of the dust grain. Particles with β ≥ 0.5 have radiation pressure at least half as strong as gravity, will pass out of the Solar System on hyperbolic orbits if their initial velocities were Keplerian. For rocky dust particles, this corresponds to a diameter of less than 1 μm. Particles with 0.1 < β < 0.5 {\displaystyle 0.1<\bet

Aries (rocket)

Aries is an American sounding rocket and target rocket, developed by Space Vector Corporation from retired LGM-30 Minuteman I intercontinental ballistic missile stages for use by the United States Air Force and NASA. Taken over by Orbital Sciences Corporation, Aries, as the Target Test Vehicle, remains in use. In the late 1960s, the retirement of the LGM-30 Minuteman I ICBM resulted in the opportunity to produce a high-performance sounding rocket from the surplus solid-propellant rockets that became available. Aries consisted of an Aerojet M56 solid-fuel rocket, the second stage of the Minuteman I, fitted with an aerodynamic nose cone and four tail fins, taken from the RIM-8 Talos surface-to-air missile, for stabilization. Steering was by gimbaled thrust. Payloads of 820 kilograms could be lifted to apogees of over 320 kilometres by Aries; the first launch of Aries, carrying a dummy payload, took place on 17 October 1973. Aries entered operational service, being used on over 20 flights to launch payloads such as X-ray telescopes and ultraviolet telescopes that were too heavy to be lifted by conventional sounding rockets.

Payloads could be recovered using a two-stage parachute system. In addition to its use as a sounding rocket, Aries was adapted for use as a target rocket to be used in the testing of anti-ballistic missiles. Contracted with Orbital Sciences Corporation for production in this role and designated the Target Test Vehicle, as of 2004, over 50 target launches had taken place testing the United States Navy's RIM-156 SM-2 Extended Range and RIM-161 Standard Missile 3 missiles. Aries at Encyclopedia Astronautica