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Packet switching

Packet switching is a method of grouping data, transmitted over a digital network into packets. Packets are made of a payload. Data in the header are used by networking hardware to direct the packet to its destination where the payload is extracted and used by application software. Packet switching is the primary basis for data communications in computer networks worldwide. In the early 1960s, American computer scientist Paul Baran developed the concept Distributed Adaptive Message Block Switching with the goal to provide a fault-tolerant, efficient routing method for telecommunication messages as part of a research program at the RAND Corporation, funded by the US Department of Defense; this concept contrasted with, contradicted, then-established principles of pre-allocation of network bandwidth fortified by the development of telecommunications in the Bell System. The new concept found little resonance among network implementers until the independent work of British computer scientist Donald Davies at the National Physical Laboratory in 1965.

Davies is credited with coining the modern term packet switching and inspiring numerous packet switching networks in the decade following, including the incorporation of the concept in the early ARPANET in the United States. A simple definition of packet switching is: The routing and transferring of data by means of addressed packets so that a channel is occupied during the transmission of the packet only, upon completion of the transmission the channel is made available for the transfer of other traffic Packet switching allows delivery of variable bit rate data streams, realized as sequences of packets, over a computer network which allocates transmission resources as needed using statistical multiplexing or dynamic bandwidth allocation techniques; as they traverse networking hardware, such as switches and routers, packets are received, buffered and retransmitted, resulting in variable latency and throughput depending on the link capacity and the traffic load on the network. Packets are forwarded by intermediate network nodes asynchronously using first-in, first-out buffering, but may be forwarded according to some scheduling discipline for fair queuing, traffic shaping, or for differentiated or guaranteed quality of service, such as weighted fair queuing or leaky bucket.

Packet-based communication may be implemented without intermediate forwarding nodes. In case of a shared physical medium, the packets may be delivered according to a multiple access scheme. Packet switching contrasts with another principal networking paradigm, circuit switching, a method which pre-allocates dedicated network bandwidth for each communication session, each having a constant bit rate and latency between nodes. In cases of billable services, such as cellular communication services, circuit switching is characterized by a fee per unit of connection time when no data is transferred, while packet switching may be characterized by a fee per unit of information transmitted, such as characters, packets, or messages. A packet switch has four components: input ports, output ports, routing processor, switching fabric; the concept of switching small blocks of data was first explored independently by Paul Baran at the RAND Corporation in the early 1960s in the US and Donald Davies at the National Physical Laboratory in the UK in 1965.

In the late 1950s, the US Air Force established a wide area network for the Semi-Automatic Ground Environment radar defense system. They sought a system that might survive a nuclear attack to enable a response, thus diminishing the attractiveness of the first strike advantage by enemies. Baran developed the concept of distributed adaptive message block switching in support of the Air Force initiative; the concept was first presented to the Air Force in the summer of 1961 as briefing B-265 published as RAND report P-2626 in 1962, in report RM 3420 in 1964. Report P-2626 described a general architecture for a large-scale, survivable communications network; the work focuses on three key ideas: use of a decentralized network with multiple paths between any two points, dividing user messages into message blocks, delivery of these messages by store and forward switching. Davies developed a similar message routing concept in 1965, he called it packet switching, proposed building a nationwide network in the UK.

He gave a talk on the proposal in 1966, after which a person from the Ministry of Defence told him about Baran's work. Roger Scantlebury, a member of Davies' team met Lawrence Roberts at the 1967 Symposium on Operating Systems Principles and suggested it for use in the ARPANET. Davies had chosen some of the same parameters for his original network design as did Baran, such as a packet size of 1024 bits. In 1966, Davies proposed that a network should be built at the laboratory to serve the needs of NPL and prove the feasibility of packet switching. After a pilot experiment in 1967, the NPL Data Communications Network entered service in 1969. Leonard Kleinrock conducted early research in queueing theory for his doctoral dissertation at MIT in 1961-2 and published it as a book in 1964 in the field of message switching. In 1968, Lawrence Roberts contracted with Kleinrock to carry out theoretical work to model the performance of the ARPANET, which underpinned the development of the network; the NPL team carried out simulation work on packet networks, including datagram networks.

The French CYCLADES network, designed by Louis Pouzin in the early 1970s, was the first to employ what came to be known as the end-to-end principle, make the hosts responsible for the reliable deliver

Warren Hastings

Warren Hastings, an English statesman, was the first Governor of the Presidency of Fort William, the head of the Supreme Council of Bengal, thereby the first de facto Governor-General of India from 1774 to 1785. In 1787, He was accused of corruption and impeached in 1787, but after a long trial acquitted in 1795, he was made a Privy Councillor in 1814. Hastings was born in Churchill, Oxfordshire in 1732 to a poor gentleman father, Penystone Hastings, a mother, Hester Hastings, who died soon after he was born. Despite Penystone Hastings's lack of wealth, the family had been lords of the manor and patrons of the living of Daylesford in direct line from 1281 until 1715, it was relinquished after there had been a considerable loss of family wealth due to support given to Charles I. Warren Hastings attended Westminster School, where he coincided with the future Prime Ministers Lord Shelburne and the Duke of Portland and with the poet William Cowper, he joined the British East India Company in 1750 as a clerk and sailed out to India, reaching Calcutta in August 1750.

There he built up a reputation for diligence and spent his free time learning about India and mastering Urdu and Persian. His work won him promotion in 1752 when he was sent to Kasimbazar, a major trading post in Bengal, where he worked for William Watts. While there he gained further experience in the politics of East India. British traders still relied on the whims of local rulers, so that the political turmoil in Bengal was unsettling; the elderly moderate Nawab Alivardi Khan was to be succeeded by his grandson Siraj ud-Daulah, but there were several other claimants. This made British trading posts throughout Bengal insecure, as Siraj ud-Daulah was known to harbour anti-European views and be to launch an attack once he took power; when Alivardi Khan died in April 1756, the British traders and a small garrison at Kasimbazar were left vulnerable. On 3 June, after being surrounded by a much larger force, the British were persuaded to surrender to prevent a massacre. Hastings was imprisoned with others in the Bengali capital, while the Nawab's forces marched on Calcutta and captured it.

The garrison and civilians were locked up under appalling conditions in the Black Hole of Calcutta. For a while Hastings remained in Murshidabad and was used by the Nawab as an intermediary, but fearing for his life, he escaped to the island of Fulta, where a number of refugees from Calcutta had taken shelter. While there, he married Mary Buchanan, the widow of one of the victims of the Black Hole. Shortly afterwards a British expedition from Madras under Robert Clive arrived to rescue them. Hastings served as a volunteer in Clive's forces as they retook Calcutta in January 1757. After this swift defeat, the Nawab urgently sought the war came to an end. Clive was impressed with Hastings when he met him, arranged for his return to Kasimbazar to resume his pre-war activities. In 1757 fighting resumed, leading to the Battle of Plassey, where Clive won a decisive victory over the Nawab. Siraj ud-Daulah was overthrown and replaced by his uncle Mir Jafar, who initiated pro-British policies. Today Mir Jafar has the reputation of a traitor in Bangladesh.

In 1758 Hastings became the British Resident in the Bengali capital of Murshidabad – a major step forward in his career – at the instigation of Clive. His role in the city was ostensibly that of an ambassador but as Bengal came under the dominance of the East India Company he was given the task of issuing orders to the new Nawab on behalf of Clive and the Calcutta authorities. Hastings sympathised with Mir Jafar and regarded many of the demands placed on him by the Company as excessive. Hastings had developed a philosophy, grounded in trying to establish a more understanding relationship with India's inhabitants and their rulers, he tried to mediate between the two sides. During Mir Jafar's reign the East India Company exerted an large role in the running of the region, took over the defence of Bengal against external invaders when Bengal's troops proved insufficient for the task; as he grew older, Mir Jafar became less effective in ruling the state, in 1760 British troops ousted him from power and replaced him with Mir Qasim.

Hastings expressed his doubts to Calcutta over the move, believing they were honour-bound to support Mir Jafar, but his opinions were overruled. Hastings established a good relationship with the new Nawab and again had misgivings about the demands he relayed from his superiors. In 1761 he was appointed to the Calcutta council. Hastings was angered when investigating trading abuses in Bengal, he alleged that some European and British-allied Indian merchants were taking advantage of the situation to enrich themselves personally. Persons travelling under the unauthorised protection of the British flag engaged in widespread fraud and illegal trading, knowing that local customs officials would be cowed into not interfering with them. Hastings felt this was bringing shame on Britain's reputation and urged the authorities in Calcutta to put an end to it; the Council considered his report but rejected Hastings' proposals. He was fiercely criticised by other members. Little was done to stem the abuses, Hastings began to consider quitting his post and returning to Britain.

His resignation was only delayed by the outbreak of fresh fighting in Bengal. Once on the throne Qasim proved independent in his actions, he rebuilt Bengal's army by hiring European instructors and mercenaries who improved the standard of his forces, he felt gradua

Burson v. Freeman

Burson v. Freeman, 504 U. S. 191, was a United States Supreme Court case in which the Court held that a Tennessee law that restricted from political campaigning within 100 feet of a polling place did not violate the First Amendment. Prior to the late 19th century, polling places lacked the privacy and decorum of more contemporary times, with campaigners allowed to directly speak to voters as they were submitting their ballots on election day, leading to voter intimidation. From the end of the 19th century into the 20th century, many states passed laws that restricted the type of activities that could be conducted around polling places. One typical law common, enacted by forty-seven states established a proximity around the polling place where political campaigning and electioneering were banned. Tennessee was one such state, which by Tennessee Code §§ 2-7-111 preventing campaigning - through verbal speech, pamphlets, or other materials - within 100 feet of a polling place. In the lead-up to the 1987 election, Mary Freeman was the treasure for the campaign for a candidate for the Metropolitan Council of Nashville and Davidson County.

She filed a suit within the Tennessee Chancery Courts to seek an injunction to permanently block enforcement of TCA §§ 2-7-111, arguing it was unconstitutional for violating the free speech rights by the First Amendment of the United States Constitution as well as the Constitution of Tennessee. The Chancery judge ruled to dismiss the complaint, finding that the statute did not violate either federal or state law, as it served a compelling state interest to avoid voter intimidation; the case was appealed to the Tennessee Supreme Court, which ruled 4-1 to overturn the lower court decision, ruled the statute unconstitutional. The Tennessee Supreme Court ruled that while the state did have a compelling interest to prevent voter intimidation within the polling place, it did not a similar case for the 100-ft space around the polling place. Further, the court believed that as long as the polling place was free of political campaigning, voters would not be deterred by last-minute campaigning before they entered the polling place.

State Attorney General Charles Burson petitioned the United States Supreme Court for writ of certorari, asking the question if the Tennessee 100-ft radius statute violated the First Amendment. The Court granted to hear the case, with oral arguments hear on October 8, 1991; the case was heard before Justice Clarence Thomas was appointed to the Supreme Court, he did not participate in the subsequent decisions. The Court issued its decision on May 26, 1992, ruling in a 5-3 vote, that the Tennessee 100-ft statute did not violate the First Amendment, reversing the lower court's judgement; the majority opinion was written by Justice Harry Blackmun, joined by Justices William Rehnquist, Byron White and Anthony Kennedy. Blackmun wrote in his opinion that "We do not view the question whether the 100-foot boundary line could be somewhat tighter as a question of constitutional dimension... The state of Tennessee has decided that these last 15 seconds before its citizens enter the polling place should be their own, as free from interference as possible.

We do not find that this is an unconstitutional choice." Justice Antonin Scalia concurred in a separate decision, though argued that Tennessee would not need a compelling reason to issue a "viewpoint-neutral" restriction on free speech. Justice John Paul Stevens wrote the dissent, joined by Justices Sandra Day O'Connor and David H. Souter. Stevens believed that the state had not shown a compelling reason to restrict free speech in the 100-ft radius; the Court's decision in Burson would be referenced in a 2018 Supreme Court case, Minnesota Voters Alliance v. Mansky. In Minnestoa Voters Alliance, the Court was presented with a challenge to a Minnesota law that restricted voters from wearing items of clothing with "political" messages; the law was challenged as unconstitutionally violating free speech rights. The lower courts had used the Court's decision in Burson to assert the Minnesota law was valid; the Court instead ruled 7-2 that unlike Burson, which set narrow bounds on what the state could restrict around polling places, the Minnesota laws was too vague on what was allowed or not, reversed the decision of lower courts.

Text of Burson v. Freeman, 504 U. S. 191 is available from: Justia Library of Congress Oyez

Institut des hautes études de défense nationale

The Institut des hautes études de défense nationale is a French public academic institution for research and promotion of expertise and sensitization towards defence matters, founded in 1936 by Admiral Raoul Castex. It was the Collège des hautes études de défense nationale and was renamed an institute in 1948. To the original national training sessions were added sessions in the regions, international sessions, economic intelligence cycles, other targeted seminars. In 1997 the Institute became a public administrative establishment placed under the authority of the Prime Minister. In 2010 it merged; the Institute is located in the École Militaire. The vocation of the Institute is to train high-level military, government officials and high-ranking executives in defence matters; some sessions are reserved for young auditors students in the foremost Grandes Ecoles, under the age of 30. In 2010, the deputy director of the defense college was Robert Ranquet. Site of the IHEDN Institute for Higher National Defence Studies

Transistor Corazón

Transistor Corazón is the third album by American singer-songwriter Melissa Greener. It was released on 14 June 2013. Produced by Brad Jones, it has been described as fusing "modernist poetry with soulful 1960s Laurel Canyon". According to Greener the album’s name comes from the English/Spanish word “transistor”, a device that amplifies, alters or changes the direction of an electrical signal, from “corazon”, the Spanish for “heart”; the songs are about the complexity and short-circuitry of romantic intimacy. The album's title song was co-written by Greener with singer-songwriter David Rodriguez. In a 4.5-starred review, The Daily Telegraph's Culture Editor, Martin Chilton, described Transistor Corazón as an "album of depth" and her songwriting as "classy". Malcolm Carter, writing for Penny Black Magazine, described her as "an exceptional talent". Greener, he said, "displays a toughness, an edge to her vocals, that makes everything she sings believable, she does make the listener part of the songs, it would appear that there is nothing fake about Greener or the music she makes...

Every word that sings is dripping with soul... The combination of Greener's distinctive vocals and the Greenfield Guitars she plays is a winning one."Allan Wilkinson, reviewing the album for Northern Sky, described it as an "intoxicating brew of fine melodies and inspired lyrics... Transistor Corazón bears all the hall marks of a breakthrough album, not too soon". Neil King, writing for FATEA magazine, said: "The dominating sound across'Transistor Corazón' is that of the torch ballad and Greener's confident, emotion laden, vocal ensures that the songs sound like they could flare at any moment giving the album an inherent tension that she tries to resolve with the lyric."Belgium's Rootstime magazine said that Melissa Greener "continues to grow as a singer but as a songwriter and entertainer... an artist whose career development we will follow with healthy interest."Fred Schmale, for the Netherlands' Real Roots Cafe, praised Greener's cover version of The Beatles' song "If I Fell" and, in particular, the string arrangements.

Erwin Zijleman for the Dutch website De krenten uit de pop, described the album as "the best roots album I have heard for ages" and "the third of Melissa Greener's addictive catalog... Melissa Greener's voice has no equal". Germany's Wasser-Prawda – Musik under Meer cultural magazine praised Greener's "voluptuously arranged folk poems", helping you paint a "dreamy atmosphere". One minute you are "in the middle of a Mexican fiesta". Italy's Roots Highway described Transistor Corazón as "a classic product of the new independent roots music" and Melissa Greener as "an artist, finding her own way"; the title track, it said, is "a if Joan Baez sang a piece of Tom Russell". Official website, with album lyrics

Pierina Legnani

Pierina Legnani was an Italian ballerina considered one of the greatest ballerinas of all time. Legnani was born on September 30, 1863, in Milan and studied with famous ballet dancer Caterina Beretta at La Scala, where she developed her technical expertise, her professional career took off when she appeared as prima ballerina in the Casati ballet, Salandra, at Alhambra Theatre in London. She was titled prima ballerina for La Scala in 1892, before moving to St Petersburg in 1892, where she reached fame dancing with the Tsar's Imperial Ballet at the Maryinsky Theatre until 1901. Under the direction of famous ballet choreographer Marius Petipa, Legnani originated numerous roles including,'Cinderella' in 1893,'Swan Lake' in 1895,'Raymonda' in 1898, and'Carmargo' in 1901, she is reputed to be the first ballerina to perform 32 fouettés en tournant in the coda of the Grand Pas d'action of the ballet Cinderella. The execution of 32 turns on pointe is a bravura achievement emphasizing the dancer's strength and technique.

A sequence of 32 fouetté turns was choreographed into the Black Swan solo in act 3 of'Swan Lake' and is still used to this day. Legnani was one of only two ballet dancers appointed prima ballerina assoluta at the Mariinsky Theatre, her last performance was in the Minkus/Petipa ballet La Camargo on January 28, 1901, after which she retired to live in her villa at Lake Como. After retiring from the stage she lived in Italy and served on the examining board of La Scala Ballet School until 4 months before her death, she died on November 15, 1930. Ballets of Marius Petipa featuring Pierina Legnani: Cinderella from Petipa/Ivanov/Cecchetti, Legnani was the first to establish 32 fouettés en tournant; the Talisman La Perle Raymonda Les ruses d’amour Coppélia The Cavalry Halt Women in dance Notes Pierina Legnani at Find a GravePierina Legnani in Lev Ivanov's revival of the choreographer Marius Petipa and the composer Ludwig Minkus's 1872 ballet La Camargo