SUMMARY / RELATED TOPICS

Plasma (physics)

Plasma is one of the four fundamental states of matter, was first described by chemist Irving Langmuir in the 1920s. It consists of a gas of ions – atoms which have some of their orbital electrons removed – and free electrons. Plasma can be artificially generated by heating or subjecting a neutral gas to a strong electromagnetic field to the point where an ionized gaseous substance becomes electrically conductive; the resulting charged ions and electrons become influenced by long-range electromagnetic fields, making the plasma dynamics more sensitive to these fields than a neutral gas. Plasma and ionized gases have properties and display behaviours unlike those of the other states, the transition between them is a matter of nomenclature and subject to interpretation. Based on the temperature and density of the environment that contains a plasma ionized or ionized forms of plasma may be produced. Neon signs and lightning are examples of ionized plasmas; the Earth's ionosphere is a plasma and the magnetosphere contains plasma in the Earth's surrounding space environment.

The interior of the Sun is an example of ionized plasma, along with the solar corona and stars. Positive charges in ions are achieved by stripping away electrons orbiting the atomic nuclei, where the total number of electrons removed is related to either increasing temperature or the local density of other ionized matter; this can be accompanied by the dissociation of molecular bonds, though this process is distinctly different from chemical processes of ion interactions in liquids or the behaviour of shared ions in metals. The response of plasma to electromagnetic fields is used in many modern technological devices, such as plasma televisions or plasma etching. Plasma may be the most abundant form of ordinary matter in the universe, although this hypothesis is tentative based on the existence and unknown properties of dark matter. Plasma is associated with stars, extending to the rarefied intracluster medium and the intergalactic regions; the word plasma comes from Ancient Greek πλάσμα​, meaning'moldable substance' or'jelly', describes the behaviour of the ionized atomic nuclei and the electrons within the surrounding region of the plasma.

Each of these nuclei are suspended in a movable sea of electrons. Plasma was first identified in a Crookes tube, so described by Sir William Crookes in 1879; the nature of this "cathode ray" matter was subsequently identified by British physicist Sir J. J. Thomson in 1897; the term "plasma" was coined by Irving Langmuir in 1928. Lewi Tonks and Harold Mott-Smith, both of whom worked with Irving Langmuir in the 1920s, recall that Langmuir first used the word "plasma" in analogy with blood. Mott-Smith recalls, in particular, that the transport of electrons from thermionic filaments reminded Langmuir of "the way blood plasma carries red and white corpuscles and germs."Langmuir described the plasma he observed as follows: "Except near the electrodes, where there are sheaths containing few electrons, the ionized gas contains ions and electrons in about equal numbers so that the resultant space charge is small. We shall use the name plasma to describe this region containing balanced charges of ions and electrons."

Plasma is a state of matter in which an ionized gaseous substance becomes electrically conductive to the point that long-range electric and magnetic fields dominate the behaviour of the matter. The plasma state can be contrasted with the other states: solid and gas. Plasma is an electrically neutral medium of unbound negative particles. Although these particles are unbound, they are not "free" in the sense of not experiencing forces. Moving charged particles generate an electric current within a magnetic field, any movement of a charged plasma particle affects and is affected by the fields created by the other charges. In turn this governs collective behaviour with many degrees of variation. Three factors define a plasma: The plasma approximation: The plasma approximation applies when the plasma parameter, Λ, representing the number of charge carriers within a sphere surrounding a given charged particle, is sufficiently high as to shield the electrostatic influence of the particle outside of the sphere.

Bulk interactions: The Debye screening length is short compared to the physical size of the plasma. This criterion means that interactions in the bulk of the plasma are more important than those at its edges, where boundary effects may take place; when this criterion is satisfied, the plasma is quasineutral. Plasma frequency: The electron plasma frequency is large compared to the electron-neutral collision frequency; when this condition is valid, electrostatic interactions dominate over the processes of ordinary gas kinetics. Plasma temperature is measured in kelvin or electronvolts and is, informally, a measure of the thermal kinetic energy per particle. High temperatures are needed to sustain ionisation, a defining feature of a plasma; the degree of plasma ionisation is determined by the electron temperature relative to the ionization energy, in a relationship called the Saha equation. At low temperatures and electrons tend to recombine into bound states—atoms—and the plasma will become a gas.

In most cases the electrons are close enough to thermal equilibrium that their temperature is well-defin

Jones (Animal Farm)

Mr. Jones of Manor Farm is a fictional character in George Orwell's allegorical novel Animal Farm. Jones is an allegory for Czar Nicholas II. Jones is overthrown by the animals of his farm, who represent liberal revolutionaries. Mr. Jones had been a capable farmer once in his lifetime, but in the aftermath of a damaging lawsuit he had become quite disheartened with his lot in life, as well as an alcoholic; this led to his neglect of both the buildings of Manor Farm. Instigated by Old Major, the animals rebel by driving out Mr. Jones, his wife and his workers, remove him from power ending the days of extreme hunger and labor. In the second chapter, an exiled Jones now lives at the Red Lion Inn, where he is feeling sorry for himself and commiserating with sympathetic and perplexed farmers. One day, the animals are at work when they see several humans on Animal Farm, not only their former masters but some neighboring farmers such as Frederick and Pilkington, all agree that Jones and his farmhands are attempting to recapture the farm.

He is defeated by Snowball's tactics. Many of the men are frightened by the organized animal defense, the animals suffer only one death. Frightened, Jones flees the farm for good. At the start of the final chapter, after'years passed', Jones is mentioned to have died in a home for alcoholics. By this time, most of the animals on the farm were either born after the Rebellion, it is mentioned that most of the deceased or exiled were forgotten - Snowball'was forgotten' as was Boxer, excepting'the few who had known him'. The days before the Rebellion have been forgotten as well. Only a few pigs, Moses the Raven and Benjamin remember Jones; the pigs and Moses have no inclination to bring their former master up - they don't mention Snowball, a scapegoat for a long number of years. Clover is an rather sick mare, past the retirement age that no longer existed. Benjamin is more cynical. In the 1954 animated adaptation of the novel, Jones was voiced by Maurice Denham, who provided all voices bar the narration.

The story is faithful to the novel, except Jones is not married and never leaves the area and instead remains in his local pub. When the other major farmers decide to make an attempt to seize Animal Farm, Jones offers to join them but is turned down. Instead, he acquires a large quantity of dynamite and destroys the windmill with himself still inside. Pete Postlethwaite portrayed Jones in the 1999 live-action film, as a brutish yokel, although his alcoholism is toned down. In this film, he and Mrs. Jones destroy the windmill together before fleeing the area. What happened to them afterwards is never revealed. Tony Robinson portrayed Jones in the 1994 featurette Down on Animal Farm, a documentary about the making of the 1954 adaptation

Siege of Riga (1656)

Siege of Riga by the Russian Army under Tsar Alexei Mikhailovich was the main event of the Russo-Swedish War. The fortifications of Riga consisted of a wall with 5 bastions around the old town. In 1652 Swedes had started construction of a new wall with 12 bastions around suburbs, but by 1656 the work had not been completed; the Russian vanguard consisting of the Vladimir v. Vizin reiters, Daniel Krafert infantry and Iunkmann dragoons approached Riga on August 20 and threw back the Swedes under count of Pärnu, Heinrich von Thurn into the city. Von Thurn was either captured in the action; the Swedes withdrew to the old town. A few days the main army under Tsar Alexei Mikhailovich arrived on the ships on the Duna River, laid siege to Riga; the Russian army occupied three camps, two on the east bank of the Duna in Riga's suburbs, a Corps under Ordyn-Nashokin on the west bank of the Duna, opposite the Kobrun entrenchment. As Russia had no full-fledged navy to intercept reinforcements coming to the Swedish garrison across the Baltic, Riga managed to hold out until October, when foreign officers commanding a small Russian flotilla defected to the other side and the Russians had to lift the siege.

In the aftermath of this reverse, the Swedes recaptured much of Ingria, took the Pskov Monastery of the Caves and inflicted a heavy defeat on the Russian general Matvey Sheremetev at Valga in 1657. The events of the siege were recorded in an engraving by Adam Perelli, first published in 1697 in Samuel Puffendorf's work, Konung Carl X Gustafs Bragder