History.

The French Communist Party (PCF) originated in 1920, when a majority of members resigned from the socialist French Section of the Workers' International (SFIO) party to set up the French Section of the Communist International (SFIC), with Ludovic-Oscar Frossard as its first secretary-general; Ho Chi Minh, liberator of Vietnam, was one of the notable agitators who participated in its creation. The new SFIC defined itself as revolutionary and democratic centralist. The 1920s saw a number of splits within the party over relations with other left-wing parties and over adherence to Comintern's dictates. The party entered the French parliament, but also promoted strike action and opposed colonialism. Pierre Sémard, leader from 1924 to 1928, sought party unity and alliances with other parties; but leaders including Maurice Thorez (party leader from 1930 to 1964) imposed a Stalinist line from the late 1920s. With the rise of Fascism after 1934 the PCF supported the Popular Front, which came to power under Léon Blum in 1936. The party supported the Spanish Republicans, and opposed the 1938 Munich agreement with Hitler.  The party was banned by the government of Édouard Daladier (centre-left) as a result of the German–Soviet Non-aggression Pact, due to its membership in the Comintern, which opposed the War (prior to the invasion of the Soviet Union by Nazi Germany). The leadership, threatened with execution, fled abroad. After the German invasion of 1940 the party began to organise opposition to the occupation. Shortly before Germany invaded the Soviet Union the next year, the PCF formed, in May 1941, the National Front movement within the broader Resistance, together with the armed "Francs-Tireurs et Partisans" (FTP) group. At the same time the PCF began to work with de Gaulle's "Free France" government in exile, and later took part in the National Council of the Resistance (CNR).  By the time the German occupation ended in 1944, the party had become a powerful force in many parts of France. It was among the leading parties in elections in 1945 and 1946, and entered into the governing Tripartite alliance, which pursued social reforms and statism. However, amid concerns within France and abroad over the extent of communist influence, the PCF was excluded from government in May 1947. Under pressure from Moscow, the PCF thereafter distanced itself from other parties and focused on agitation within its trade union base. For the rest of the Fourth Republic period the PCF, led by Thorez and Jacques Duclos, remained politically isolated, still taking a Stalinist line, though retaining substantial electoral support.  Although the PCF opposed de Gaulle's formation of the Fifth Republic in 1958, the following years saw a "rapprochement" with other left-wing forces and an increased strength in parliament. With Waldeck Rochet as its new secretary-general, the party supported François Mitterrand's unsuccessful presidential bid in 1965. During the student riots and strikes of May 1968, the party supported the strikes while denouncing the revolutionary student movements. After heavy losses in the ensuing parliamentary elections, the party adopted Georges Marchais as leader and in 1973 entered into a "Common Programme" alliance with Mitterrand's reconstituted Socialist Party (PS). Under the Common Programme, however, the PCF steadily lost ground to the PS, a process that continued after Mitterrand's victory in 1981. Initially allotted a minor share in Mitterrand's government, the PCF resigned in 1984 as the government turned towards fiscal orthodoxy. Under Marchais the party largely maintained its traditional communist doctrines and structure. Extensive reform was undertaken after 1994, when Robert Hue became leader. This did little to stem the party's declining popularity, although it entered government again in 1997 as part of the Plural Left coalition. Elections in 2002 gave worse results than ever for the PCF. Under Marie-George Buffet, the PCF turned away from parliamentary strategy and sought broader social alliances. To maintain a presence in parliament after 2007 the party's few remaining deputies had to join others in the Democratic and Republican Left group (GDR). Subsequently a broader electoral coalition, the Left Front (FG), was formed including the PCF, the Left Party (PG), United Left, and others. The FG has brought the French communists somewhat better electoral results. Pierre Laurent was leader from 2010 to 2018.

Doctrine.

The PCF, in contrast to weaker and more marginal communist parties in Europe, is usually seen as a left-wing rather than far-left party in the French context. While the French far-left (LCR/NPA, LO) has refused to participate in government or engage in electoral alliances with centre-left parties such as the PS, the PCF has participated in governments in the past and still enjoys a "de facto" electoral agreement with the PS (mutual withdrawals, the common practice since 1962 and in 1934–39). Nonetheless, some observers and analysts classify the PCF as a far-left party, noting their political proximity to other far-left parties.  In the 1980s, under Georges Marchais, the PCF mixed a partial acceptance of "bourgeois" democracy and individual liberties with more traditional Marxist–Leninist rhetoric. During this same period, however, the PCF—still run on democratic centralist lines—still structured itself as a revolutionary party in the Leninist sense and rejected criticism of the Soviet Union. Under Robert Hue's leadership after 1994, the PCF's ideology and internal organization underwent major changes. Hue clearly rejected the Soviet model, and reserved very harsh criticism for Soviet leaders who had "rejected, for years, human rights and 'bourgeois' democracy" and had oppressed individual liberties and aspirations. Today, the PCF considers the Soviet Union as a 'perversion' of the communist model and unambiguously rejects Stalinism. That being said, it has not attributed the failure of the Soviet Union as being that of communism, rather stating that the failure of Soviet socialism was the failure of one model "among others", including the capitalist or social democratic models. It also tried to downplay the PCF's historic attachment to Moscow and the Soviet Union.  Since then, the PCF's ideology has been marked by significant ideological evolution on some topics but consistency on other issues. Some of the most marked changes have come on individual rights and immigration. After having vilified homosexuality and feminism as "the rubbish of capitalism" in the 1970s, the PCF now fully supports both gay rights and feminism. In the 1980s, the PCF supported reducing the age of consent for homosexual relationships and opposed attempts to repenalize homosexuality. In 1998, the PCF voted in favour of the civil solidarity pact (PACS), civil unions including homosexual couples. The PCF currently supports both same-sex marriage and same-sex adoption. On 12 February 2013, PCF deputies voted in favour of same-sex marriage and adoption rights in the National Assembly, though PCF deputy voted against. The PCF also supports feminist movements and supports policies to further promote gender equality and parity.  On the issue of immigration, the PCF's positions have also evolved significantly since the 1980s. In the 1981 presidential election, Georges Marchais ran a controversial campaign on immigration which was harshly criticized by anti-racism organizations at the time. In 1980, the PCF's leadership voted in favour of limiting immigration. The same year, Marchais supported the PCF mayor of Vitry-sur-Seine who had destroyed a home for Malian migrant workers; the PCF claimed that the right-wing government was trying to push immigrants into ghettos in Communist working-class cities. The "Libération" newspaper also alleged that PCF municipal administrations had been working to limit the number of immigrants in housing projects. However, today the PCF supports the regularization of illegal immigrants.  One consistency in the PCF's ideology has been its staunch opposition to capitalism, which must be "overcome" because according to the PCF the capitalist system is "exhausted" and "on the verge of collapse". The PCF has interpreted the current course of globalization as a confirmation of Karl Marx and Friedrich Engels's view on the future evolution of capitalism. The party feels that the financial crisis of 2007–2008 and the Great Recession have further justified its calls to overcome capitalism. However, the PCF has remained somewhat vague on how capitalism will be 'overcome' and what will replace it, placing heavy emphasis on utopic models or values.  The text adopted at the XXXVI Congress in February 2013 reiterated the party's call on the need to "overcome" capitalism, fiercely denounced by the PCF as having led to "savage competition", "the devastation of the planet" and "barbarism". It contrasts its vision of capitalism with its proposed alternative, described as an egalitarian, humanist, and democratic alternative. It emphasizes human emancipation, the development of "each and every one", the right to happiness and the equal dignity of each human being regardless of gender, race or sexual orientation. The party further posits that such an egalitarian society is impossible within capitalism, which "unleashes domination and hatred".

2012 platform.

Jean-Luc Mélenchon and the FG's platform in the 2012 presidential election was broken up into nine overarching themes.  The platform also supported same-sex marriage, same-sex adoption, voting rights for resident foreigners, euthanasia, and constitutional recognition of abortion.

French nationalism.

The French Communist Party inherited from the Jacobins the concept of France as a centralised, French-speaking, unitary state, with a unitary culture and it is opposed to the separatism and regional identity of other European minority groups native to the area of what consists the French Republic. For instance in 1984, the Soviet ethnographer Solomon Bruk (who had worked under Sergey Tolstov) published a study on France and mentioned the existence of other ethnic groups in the state such as Bretons, Corsicans, Alsatians, Basques, Catalans, Flemish and others. In response to this work, General Secretary Georges Marchais wrote a letter of protest in February 1984, complaining bitterly to the Secretariat of the Communist Party of the Soviet Union.

Elected officials.

The PCF has two Presidents of the General Council – in the Val-de-Marne and Allier. It lost Seine-Saint-Denis, which it had held since the 1960s, to the PS in 2008.

Internal organization.

The PCF has traditionally been a "mass party", although Maurice Duverger had differentiated it from other mass parties because the PCF kept a tight control over membership and regularly expelled unsuitable members. In its heyday, the PCF maintained a large base of members and the party's political and electoral actions were supported in society by a trade union, the General Confederation of Labour (CGT); a newspaper, "L'Humanité"; and a large number of front organizations or associations in civil society which organized a large number of political or non-political social activities for PCF members. One such activity which still exists today is the annual "Fête de l'Humanité" organized by the "L'Humanité". French and foreign left-wing parties, organizations or movements are represented and the activities feature musical performances.  Since the PCF's decline began in the 1970s, however, it has seen its membership base slowly dry up and its allied organizations disappear or distance themselves from the party. The PCF claimed 520,000 members in 1978; 330,000 in 1987; 270,000 in 1996; and 133,000 in 2002. In 2008, the party claimed that it had 134,000 members of which 79,000 were up to date on their membership fees. In the 2011 internal primary, 69,277 members were registered to vote and 48,631 (70.2%) did so. The party likely has about 70,000 members as of today, but only about 40 to 50 thousand seem to actively participate in the party's organization and political activities.  According to studies by the CEVIPOF in 1979 and 1997, the makeup of the PCF's membership has also changed significantly since 1979. The most marked change was a major decline in the share of manual workers ("ouvriers") in the party's membership, with a larger number of employees and middle-classes, especially those who work in the public sector. The form of political action taken by members has also changed, with less emphasis on direct political or electoral action but a greater emphasis on social work and protests.  The party's structures were democratized at the 1994 Congress, dropping democratic centralism and allowing for the public expression of disapproval or dissent with the party line or leadership. The party's top posts, like that of'secretary-general', were renamed (secretary-general became national-secretary). The party, since 2000, is now led by a national council, which serves as the leadership between congresses; and the executive committee, which is charged with applying the national council's decisions. The national-secretary is elected by delegates at the congress. Likewise, the national council is elected by list voting at every congress. A reform of statutes in 2001 has allowed "alternative texts" - dissent from the text proposed by the PCF leadership - to be presented and voted on; dissident lists to those backed by the leadership may also run for the national council.  The General Confederation of Labour (CGT) was dominated by the PCF after 1946, with almost all its leaders between 1947 and 1996 (Benoît Frachon, Georges Séguy, Henri Krasucki, Louis Viannet) also serving in the PCF's national leadership structures. For years, the CGT and the PCF were close and almost indissociable allies - notably in May 1968 when both the CGT and PCF were eager for a restoration of social order and welcomed the Grenelle agreements. While the CGT has remained the largest trade union in France, it has taken its independence vis-à-vis the PCF. Louis Viannet spectacularly quit the national bureau of the PCF in 1996 and Bernard Thibault, the CGT's leader between 1999 and 2013, left the PCF's national council in 2001.  "L'Humanité" has retained closer ties with the PCF. The newspaper was founded by Jean Jaurès in 1904 as the socialist movement's mouthpiece, and it followed the communist majority following the split in 1920. After having been the official newspaper of the PCF, with a readership of up to 100,000 in 1945, the newspaper's readership and sales declined substantially partly due to the PCF's concomitant decline. In 1999, the mention of the newspaper's link to the PCF was dropped and the PCF no longer determines its editorial stance. It sold an average of 46,929 newspapers per day in 2012; down from 53,530 in 2007.

Leadership.

Secretaries-general (1921–1994) and national-secretaries (since 1994)

Factions.

There are no formal organized factions or political groupings within the PCF. This was originally due to the practice of democratic centralism, but even after the democratization of the PCF structure after 1994 the ban on the organization of formal factions within the party remained. According to party statutes, the PCF supports the "pluralism of ideas" but the right to pluralism "may not be translated into an organizations of tendencies". Nevertheless, certain factions and groups are easily identifiable within the PCF and they are "de facto" expressed officially by different orientation texts or lists for leadership elections at party congresses.

Factional strength.

Preparatory votes on orientation texts for PCF Congresses since 2003: At the XXXIV Congress in 2008, for the election of the national council, the majority's list won 67.73% from the congress' delegates against 16.38% for Marie-Pierre Vieu's "huiste" list backed by the "refondateurs", 10.26% for André Gerin's orthodox list and 5.64% for Nicolas Marchand's "novateur" list.

Popular support and electoral record.

Currently, the PCF retains some strength in suburban Paris, in the Nord section of the old coal mining area in the Nord-Pas-de-Calais, the industrial harbours of Le Havre and Dieppe, in some departments of central France, such as Allier and Cher (where a form of sharecropping existed, in addition to mining and small industrial-mining centres such as Commentry and Montceau-les-Mines), the industrial mining region of northern Meurthe-et-Moselle (Longwy) and in some cities of the south, such as the industrial areas of Marseille and nearby towns, as well as the working-class suburbs surrounding Paris (the "ceinture rouge"), Lyon, Saint-Étienne, Alès and Grenoble. The PCF is also strong in the Cévennes mountains, a left-wing rural anti-clerical stronghold with a strong Protestant minority.  Communist traditions in the "Red Limousin", the Pas-de-Calais, Paris proper, Nièvre, Finistère, Alpes-Maritimes and Var have been hurt significantly by demographic changes (Var, Alpes-Maritimes, Finistère), a loss of voters to the Socialist Party due to good local Socialist infrastructure or strongmen (Nièvre, Pas-de-Calais, Paris) or due to the emergence of rival parties on the radical left (the Convention for a Progressive Alternative, a party of reformist communists, in the Limousin and Val-de-Marne).  There exists isolated Communist bases in the rural anti-clerical areas of southwestern Côtes-d'Armor and northwestern Morbihan; in the industrial areas of Le Mans; in the shipbuilding cities of Saint-Nazaire, La Seyne-sur-Mer (there are no more ships built in La Seyne); and in isolated industrial centres built along the old Paris-Lyon railway (The urban core of Romilly-sur-Seine, Aube has elected a Communist general councillor since 1958).  During the course of the Twentieth Century, the French Communists were considered to be pioneers in local government, providing not only efficient street lighting and clean streets, but also public entertainment, public housing, municipal swimming pools, day nurseries, children’s playgrounds, and public lavatories. In 1976, for instance, the Communist mayor of Sarcelles, Henry Canacos, was named "best mayor in the Paris region" by Vie Publique (a trade periodical for urban planners and administrators) for enriching Sarcelles' public spaces with new restaurants, movie theatres, cafes, more parks, a large shopping mall, and better transportation. Education also became, in the words of one text, an "identifiable characteristic of Communist government at the local level". A study of municipal budgets that was completed in 1975 (but using data from 1968) found that while Communist local government spent 34% less than non-Communist Left governments and 36% less than moderate-Right governments for maintenance, it nevertheless spent 49% more than moderate Right governments and 36% more than non-Communist Left governments for education and educational support.

Publications.

The PCF publishes the following:  Traditionally, it was also the owner of the French daily "L'Humanité" ("Humanity"), founded by Jean Jaurès. Although the newspaper is now independent, it remains close to the PCF. The paper is sustained by the annual "Fête de L'Humanité" festival, held in La Courneuve, a working class suburb of Paris. This event remains the biggest festival in France, with attendees during a three-day period.  During the 1970s, the PCF registered success with the children's magazine it founded, "Pif gadget".

The French Communist Party (, "PCF" ; ) is a communist party in France. Although its electoral support has declined in recent decades, the PCF retains a strong influence in French politics, especially at the local level. In 2012, the PCF claimed 138,000 members including 70,000 who have paid their membership fees. This would make it the third largest party in France in terms of membership after The Republicans (LR) and the Socialist Party (PS).

Le Parti communiste français (PCF) est un parti politique français fondé en 1920. Il est issu du congrès de Tours de la Section française de l'Internationale ouvrière (SFIO) visant à décider de l'adhésion à l'Internationale communiste ; la majorité du congrès ayant décidé de cette adhésion crée alors la Section française de l'Internationale communiste (SFIC), la minorité restant au sein de la SFIO. Le parti devient en 1921 le Parti communiste (SFIC), abrégé en PC-SFIC, puis le PCF en 1943.


Elements of painting.

Color and tone.

Color, made up of hue, saturation, and value, dispersed over a surface is the essence of painting, just as pitch and rhythm are the essence of music. Color is highly subjective, but has observable psychological effects, although these can differ from one culture to the next. Black is associated with mourning in the West, but in the East, white is. Some painters, theoreticians, writers and scientists, including Goethe, Kandinsky, and Newton, have written their own color theory.  Moreover, the use of language is only an abstraction for a color equivalent. The word "red", for example, can cover a wide range of variations from the pure red of the visible spectrum of light.

Non-traditional elements.

Modern artists have extended the practice of painting considerably to include, as one example, collage, which began with Cubism and is not painting in the strict sense. Some modern painters incorporate different materials such as metal, plastic, sand,

Rhythm.

Jean Metzinger's mosaic-like Divisionist technique had its parallel in literature; a characteristic of the alliance between Symbolist writers and Neo-Impressionist artists:  I ask of divided brushwork not the objective rendering of light, but iridescences and certain aspects of color still foreign to painting. I make a kind of chromatic versification and for syllables I use strokes which, variable in quantity, cannot differ in dimension without modifying the rhythm of a pictorial phraseology destined to translate the diverse emotions aroused by nature. (Jean Metzinger, circa 1907) Rhythm, for artists such as Piet Mondrian, is important in painting as it is in music. If one defines rhythm as "a pause incorporated into a sequence", then there can be rhythm in paintings. These pauses allow creative force to intervene and add new creations—form, melody, coloration. The distribution of form, or any kind of information is of crucial importance in the given work of art, and it directly affects

History.

The oldest known paintings are at the Grotte Chauvet in France, which some historians believe are about 32,000 years old. They are engraved and painted using red ochre and black pigment, and they show horses, rhinoceros, lions, buffalo, mammoth, abstract designs and what are possibly partial human figures. However, the earliest evidence of the act of painting has been discovered in two rock-shelters in Arnhem Land, in northern Australia. In the lowest layer of material at these sites, there are used pieces of ochre estimated to be 60,000 years old. Archaeologists have also found a fragment of rock painting preserved in a limestone rock-shelter in the Kimberley region of North-Western Australia, that is dated 40,000 years old. There are examples of cave paintings all over the world—in Italy, France, Spain, Portugal, China, Australia, Mexico, etc. In Western cultures, oil painting and watercolor painting have rich and complex traditions in style

Aesthetics and theory.

Aesthetics is the study of art and beauty; it was an important issue for 18th- and 19th-century philosophers such as Kant and Hegel. Classical philosophers like Plato and Aristotle also theorized about art and painting in particular. Plato disregarded painters (as well as sculptors) in his philosophical system; he maintained that painting cannot depict the truth—it is a copy of reality (a shadow of the world of ideas) and is nothing but a craft, similar to shoemaking or iron casting. By the time of Leonardo, painting had become a closer representation of the truth than painting was in Ancient Greece. Leonardo da Vinci, on the contrary, said that "" (""). Kant distinguished between Beauty and the Sublime, in terms that clearly gave priority to the former. Although he did not refer to painting in particular, this concept was taken up by painters such as J.M.W. Turner and Caspar David Friedrich.  Hegel recognized the failure of attaining a universal concept of beauty and, in his aesthetic essay, wrote

Painting media.

Different types of paint are usually identified by the medium that the pigment is suspended or embedded in, which determines the general working characteristics of the paint, such as viscosity, miscibility, solubility, drying time, etc.

Oil.

Oil painting is the process of painting with pigments that are bound with a medium of drying oil, such as linseed oil, which was widely used in early modern Europe. Often the oil was boiled with a resin such as pine resin

Pastel.

Pastel is a painting medium in the form of a stick, consisting of pure powdered pigment and a binder. The pigments used in pastels are the same as those used to produce all colored art media, including oil paints; the binder is of a neutral hue and low saturation. The color effect of pastels is closer to the natural

Acrylic.

Acrylic paint is fast drying paint containing pigment suspension in acrylic polymer emulsion. Acrylic paints can be diluted with water, but become water-resistant when dry. Depending on how much the paint is diluted (with water) or modified with acrylic gels, media, or pastes, the finished acrylic painting can

Watercolor.

Watercolor is a painting method in which the paints are made of pigments suspended in a water-soluble vehicle. The traditional and most common support for watercolor paintings is paper; other supports include papyrus, bark papers, plastics, vellum or leather, fabric, wood and

Ink.

Ink paintings are done with a liquid that contains pigments and/or dyes and is used to color a surface to produce an image, text, or design. Ink is used for drawing with a pen,

Hot wax or encaustic.

Encaustic painting, also known as hot wax painting, involves using heated beeswax to which colored pigments are added. The liquid/paste is then applied to a surface—usually prepared wood, though canvas and other materials are often used. The simplest encaustic mixture can be made from adding pigments to beeswax, but there are several other recipes that can be used—some containing other types of waxes, damar resin, linseed oil,

Fresco.

Fresco is any of several related mural painting types, done on plaster on walls or ceilings. The word fresco comes from the Italian word "affresco", which derives from the Latin word for "fresh". Frescoes were often made during the Renaissance and other early time

Gouache.

Gouache is a water-based paint consisting of pigment and other materials designed to be used in an opaque painting method. Gouache differs from watercolor in that the particles

Enamel.

Enamels are made by painting a substrate, typically metal, with powdered glass; minerals called color oxides provide coloration. After firing at a temperature of 750–850 degrees Celsius (1380–1560 degrees Fahrenheit), the result is a fused lamination of glass and metal. Unlike most painted techniques, the surface can be handled and wetted Enamels have traditionally been

Spray paint.

Aerosol paint (also called spray paint) is a type of paint that comes in a sealed pressurized container and is released in a fine spray mist when depressing a valve button. A form of spray painting, aerosol paint leaves a smooth, evenly coated surface. Standard sized cans are portable, inexpensive and easy to store. Aerosol primer can be applied directly to bare metal and many

Tempera.

Tempera, also known as egg tempera, is a permanent, fast-drying painting medium consisting of colored pigment mixed with a water-soluble binder medium (usually a glutinous material such as egg yolk or some other size). Tempera also refers to the paintings done in this medium.

Water miscible oil paint.

Water miscible oil paints (also called "water soluble" or "water-mixable") is a modern variety of oil paint engineered to be thinned and cleaned up with water, rather than having to use chemicals such as turpentine. It can be mixed and

Digital painting.

Digital painting is a method of creating an art object (painting) digitally and/or a technique for making digital art in the computer. As a method of creating an art object, it adapts traditional painting medium such as acrylic paint, oils, ink, watercolor, etc. and applies the pigment to traditional carriers, such as woven canvas cloth, paper, polyester etc. by means of computer software driving industrial robotic or office machinery

Painting styles.

"Style" is used in two senses: It can refer to the distinctive visual elements, techniques and methods that typify an "individual" artist's work. It can also refer to the movement or school that an artist is associated with. This can stem from an actual group that the artist was consciously involved with or it can be a category in which art historians have placed the painter. The word'style' in the latter sense has fallen out of favor in academic discussions about contemporary painting, though it continues to be used in popular contexts. Such movements or classifications include the following:

Western.

Modernism.

Modernism describes both a set of cultural tendencies and an array of associated cultural movements, originally arising from wide-scale and far-reaching changes to Western society in the late 19th century and early 20th century. Modernism was a revolt against the conservative values of realism. The term encompasses the activities and output of those who felt the "traditional" forms of art, architecture, literature, religious faith, social organization and daily life were becoming outdated in the new economic, social and political conditions of an emerging fully industrialized world. A salient characteristic of modernism is self-consciousness. This often led to experiments with form, and work that draws attention to the processes and materials used (and to the further tendency of abstraction).

Types of painting.

Allegory.

Allegory is a figurative mode of representation conveying meaning other than the literal. Allegory communicates its message by means of symbolic figures, actions or symbolic representation. Allegory is generally treated as a figure of rhetoric, but

Bodegón.

In Spanish art, a bodegón is a still life painting depicting pantry items, such as victuals, game, and drink, often arranged on a simple stone slab, and also a painting with one or more figures, but significant still life elements, typically set in a kitchen or tavern. Starting in the Baroque period, such paintings became popular in Spain in the second quarter

Figure painting.

A figure painting is a work of art in any of the painting media with the primary subject being the human figure, whether clothed or nude. Figure painting may also refer to the

Illustration painting.

Illustration paintings are those used as illustrations in books, magazines, and theater or movie posters and comic books. Today, there is a growing interest in collecting and admiring the original artwork. Various museum exhibitions, magazines and art galleries have devoted space to the

Landscape painting.

Landscape painting is a term that covers the depiction of natural scenery such as mountains, valleys, trees, rivers, and forests, and especially art where the main subject is a wide view, with its elements arranged into a coherent composition. In other works landscape backgrounds for figures can still

Portrait painting.

Portrait paintings are representations of a person, in which the face and its expression is predominant. The intent is to display the likeness, personality, and even the mood of the person. The art of the

Still life.

A still life is a work of art depicting mostly inanimate subject matter, typically commonplace objects—which may be either natural (food, flowers, plants, rocks, or shells) or man-made (drinking glasses, books, vases, jewelry, coins, pipes, and so on). With origins in the Middle Ages and Ancient Greek/Roman art,

Veduta.

A veduta is a highly detailed, usually large-scale painting of a cityscape or some other vista. This genre of landscape originated in Flanders, where artists such as Paul Bril painted "vedute" as early as the 16th

Painting is the practice of applying paint, pigment, color or other medium to a solid surface (called the "matrix" or "support"). The medium is commonly applied to the base with a brush, but other implements, such as knives, sponges, and airbrushes, can be used. The final work is also called a painting.

La peinture est une forme d'art consistant à peindre sur une surface en y appliquant esthétiquement des fluides colorés. Les artistes peintres représentent une expression très personnelle sur des supports tels que le papier, la roche, la toile, le bois, l'écorce, le verre, le béton et bien d'autres subjectiles.


History.

The history of the term is somewhat vague, and it had been used in many contexts: forest classifications (Loucks, 1962), biome classifications (Bailey, 1976, 2014), biogeographic classifications (WWF/Global 200 scheme of Olson & Dinerstein, 1998), etc.  The concept of ecoregion applied by Bailey gives more importance to ecological criteria and climate, while the WWF concept gives more importance to biogeography, that is, the distribution of distinct species assemblages.

Definition and categorization.

An ecoregion is a "recurring pattern of ecosystems associated with characteristic combinations of soil and landform that characterise that region". Omernik (2004) elaborates on this by defining ecoregions as: "areas within which there is spatial coincidence in characteristics of geographical phenomena associated with differences in the quality, health, and integrity of ecosystems". "Characteristics of geographical phenomena" may include geology, physiography, vegetation, climate, hydrology, terrestrial and aquatic fauna, and soils, and may or may not include the impacts of human activity (e.g. land use patterns, vegetation changes). There is significant, but not absolute, spatial correlation among these characteristics, making the delineation of ecoregions an imperfect science. Another complication is that environmental conditions across an ecoregion boundary may change very gradually, e.g. the prairie-forest transition in the midwestern United States, making it difficult to identify an exact dividing boundary. Such transition zones are called ecotones.  Ecoregions can be categorized using an algorithmic approach or a holistic, "weight-of-evidence" approach where the importance of various factors may vary. An example of the algorithmic approach is Robert Bailey's work for the U.S. Forest Service, which uses a hierarchical classification that first divides land areas into very large regions based on climatic factors, and subdivides these regions, based first on dominant potential vegetation, and then by geomorphology and soil characteristics. The weight-of-evidence approach is exemplified by James Omernik's work for the United States Environmental Protection Agency, subsequently adopted (with modification) for North America by the Commission for Environmental Cooperation.  The intended purpose of ecoregion delineation may affect the method used. For example, the WWF ecoregions were developed to aid in biodiversity conservation planning, and place a greater emphasis than the Omernik or Bailey systems on floral and faunal differences between regions. The WWF classification defines an ecoregion as:  A large area of land or water that contains a geographically distinct assemblage of natural communities that:  According to WWF, the boundaries of an ecoregion approximate the original extent of the natural communities prior to any major recent disruptions or changes. WWF has identified 867 terrestrial ecoregions, and approximately 450 freshwater ecoregions across the Earth.

Importance.

The use of the term ecoregion is an outgrowth of a surge of interest in ecosystems and their functioning. In particular, there is awareness of issues relating to spatial scale in the study and management of landscapes. It is widely recognized that interlinked ecosystems combine to form a whole that is "greater than the sum of its parts". There are many attempts to respond to ecosystems in an integrated way to achieve "multi-functional" landscapes, and various interest groups from agricultural researchers to conservationists are using the "ecoregion" as a unit of analysis.  The "Global 200" is the list of ecoregions identified by WWF as priorities for conservation.  Ecologically based movements like bioregionalism maintain that ecoregions, rather than arbitrarily defined political boundaries, provide a better foundation for the formation and governance of human communities, and have proposed ecoregions and watersheds as the basis for bioregional democracy initiatives.

Terrestrial.

Terrestrial ecoregions are land ecoregions, as distinct from freshwater and marine ecoregions. In this context, "terrestrial" is used to mean "of land" (soil and rock), rather than the more general sense "of Earth" (which includes land and oceans).  WWF (World Wildlife Fund) ecologists currently divide the land surface of the Earth into eight biogeographical realms containing 867 smaller terrestrial ecoregions (see list). The WWF effort is a synthesis of many previous efforts to define and classify ecoregions. Many consider this classification to be quite decisive, and some propose these as stable borders for bioregional democracy initiatives.  The eight realms follow the major floral and faunal boundaries, identified by botanists and zoologists, that separate the world's major plant and animal communities. Realm boundaries generally follow continental boundaries, or major barriers to plant and animal distribution, like the Himalayas and the Sahara. The boundaries of ecoregions are often not as decisive or well recognized, and are subject to greater disagreement.  Ecoregions are classified by biome type, which are the major global plant communities determined by rainfall and climate. Forests, grasslands (including savanna and shrubland), and deserts (including xeric shrublands) are distinguished by climate (tropical and subtropical vs. temperate and boreal climates) and, for forests, by whether the trees are predominantly conifers (gymnosperms), or whether they are predominantly broadleaf (Angiosperms) and mixed (broadleaf and conifer). Biome types like Mediterranean forests, woodlands, and scrub; tundra; and mangroves host very distinct ecological communities, and are recognized as distinct biome types as well.

Marine.

Marine ecoregions are: "Areas of relatively homogeneous species composition, clearly distinct from adjacent systems....In ecological terms, these are strongly cohesive units, sufficiently large to encompass ecological or life history processes for most sedentary species." They have been defined by The Nature Conservancy (TNC) and World Wildlife Fund (WWF) to aid in conservation activities for marine ecosystems. Forty-three priority marine ecoregions were delineated as part of WWF's Global 200 efforts. The scheme used to designate and classify marine ecoregions is analogous to that used for terrestrial ecoregions. Major habitat types are identified: polar, temperate shelves and seas, temperate upwelling, tropical upwelling, tropical coral, pelagic (trades and westerlies), abyssal, and hadal (ocean trench). These correspond to the terrestrial biomes.  The Global 200 classification of marine ecoregions is not developed to the same level of detail and comprehensiveness as that of the terrestrial ecoregions; only the priority conservation areas are listed.  See Global 200 Marine ecoregions for a full list of marine ecoregions.  In 2007, TNC and WWF refined and expanded this scheme to provide a system of comprehensive near shore (to 200 meters depth) Marine Ecoregions of the World (MEOW). The 232 individual marine ecoregions are grouped into 62 marine provinces, which in turn group into 12 marine realms, which represent the broad latitudinal divisions of polar, temperate, and tropical seas, with subdivisions based on ocean basins (except for the southern hemisphere temperate oceans, which are based on continents).  Major marine biogeographic realms, analogous to the eight terrestrial biogeographic realms, represent large regions of the ocean basins: Arctic, Temperate Northern Atlantic, Temperate Northern Pacific, Tropical Atlantic, Western Indo-Pacific, Central Indo-Pacific, Eastern Indo-Pacific, Tropical Eastern Pacific, Temperate South America, Temperate Southern Africa, Temperate Australasia, and Southern Ocean.  A similar system of identifying areas of the oceans for conservation purposes is the system of large marine ecosystems (LMEs), developed by the US National Oceanic and Atmospheric Administration (NOAA).

Freshwater.

A freshwater ecoregion is a large area encompassing one or more freshwater systems that contains a distinct assemblage of natural freshwater communities and species. The freshwater species, dynamics, and environmental conditions within a given ecoregion are more similar to each other than to those of surrounding ecoregions and together form a conservation unit. Freshwater systems include rivers, streams, lakes, and wetlands. Freshwater ecoregions are distinct from terrestrial ecoregions, which identify biotic communities of the land, and marine ecoregions, which are biotic communities of the oceans.  A map of Freshwater Ecoregions of the World, released in 2008, has 426 ecoregions covering virtually the entire non-marine surface of the earth.  World Wildlife Fund (WWF) identifies twelve major habitat types of freshwater ecoregions: Large lakes, large river deltas, polar freshwaters, montane freshwaters, temperate coastal rivers, temperate floodplain rivers and wetlands, temperate upland rivers, tropical and subtropical coastal rivers, tropical and subtropical floodplain rivers and wetlands, tropical and subtropical upland rivers, xeric freshwaters and endorheic basins, and oceanic islands. The freshwater major habitat types reflect groupings of ecoregions with similar biological, chemical, and physical characteristics and are roughly equivalent to biomes for terrestrial systems.  The Global 200, a set of ecoregions identified by WWF whose conservation would achieve the goal of saving a broad diversity of the Earth's ecosystems, includes a number of areas highlighted for their freshwater biodiversity values. The Global 200 preceded Freshwater Ecoregions of the World and incorporated information from regional freshwater ecoregional assessments that had been completed at that time.

Bibliography.

Sources related to the WWC scheme: Others:

An ecoregion (ecological region) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural communities and species. The biodiversity of flora, fauna and ecosystems that characterise an ecoregion tends to be distinct from that of other ecoregions. In theory, biodiversity or conservation ecoregions are relatively large areas of land or water where the probability of encountering different species and communities at any given point remains relatively constant, within an acceptable range of variation (largely undefined at this point).

Une écorégion ou région écologique est une zone géographique assez large se distinguant par le caractère unique de sa géomorphologie, de sa géologie, de son climat, de ses sols, de ses ressources en eau, de sa faune et de sa flore. Plusieurs organismes internationaux ont établi des listes d'écorégions, le World Wildlife Fund, la Commission de coopération environnementale d'Amérique du Nord, la DMEEReuropéenne, la National Oceanic and Atmospheric Administration américaine. Les zones désignées par chacun de ces organismes ne doivent pas être confondues car ils n'utilisent pas le même critère de désignation.


Hazards.

Chemical hazards typically found in laboratory settings include carcinogens, toxins, irritants, corrosives, and sensitizers. Biological hazards include viruses, bacteria, fungi, prions, and biologically-derived toxins, which may be present in body fluids and tissue, cell culture specimens, and laboratory animals. Routes of exposure for chemical and biological hazards include inhalation, ingestion, skin contact, and eye contact.  Physical hazards include ergonomic hazards, ionizing and non-ionizing radiation, and noise hazards. Additional safety hazards include burns and cuts from autoclaves, injuries from centrifuges, compressed gas leaks, cold burns from cryogens, electrical hazards, fires, injuries from machinery, and falls.

In synthetic biology.

A complete understanding of experimental risks associated with synthetic biology is helping to enforce the knowledge and effectiveness of biosafety. With the potential future creation of man-made unicellular organisms, some are beginning to consider the effect that these organisms will have on biomass already present. Scientists estimate that within the next few decades, organism design will be sophisticated enough to accomplish tasks such as creating biofuels and lowering the levels of harmful substances in the atmosphere. Scientist that favor the development of synthetic biology claim that the use of biosafety mechanisms such as suicide genes and nutrient dependencies will ensure the organisms cannot survive outside of the lab setting in which they were originally created. Organizations like the ETC Group argue that regulations should control the creation of organisms that could potentially harm existing life. They also argue that the development of these organisms will simply shift the consumption of petroleum to the utilization of biomass in order to create energy. These organisms can harm existing life by affecting the prey/predator food chain, reproduction between species, as well as competition against other species (species at risk, or act as an invasive species). Synthetic vaccines are now being produced in the lab. These have caused a lot of excitement in the pharmaceutical industry as they will be cheaper to produce, allow quicker production, as well as enhance the knowledge of virology and immunology.

In medicine, healthcare settings and laboratories.

Biosafety, in medicine and health care settings, specifically refers to proper handling of organs or tissues from biological origin, or genetic therapy products, viruses with respect to the environment, to ensure the safety of health care workers, researchers, lab staff, patients, and the general public. Laboratories are assigned a biosafety level numbered 1 through 4 based on their potential biohazard risk level. The employing authority, through the laboratory director, is responsible for ensuring that there is adequate surveillance of the health of laboratory personnel. The objective of such surveillance is to monitor for occupationally acquired diseases. The World Health Organization attributes human error and poor technique as the primary cause of mishandling of biohazardous materials.  Biosafety is also becoming a global concern and requires multilevel resources and international collaboration to monitor, prevent and correct accidents from unintended and malicious release and also to prevent that bioterrorists get their hands-on biologics sample to create biologic weapons of mass destruction. Even people outside of the health sector needs to be involved as in the case of the Ebola outbreak the impact that it had on businesses and travel required that private sectors, international banks together pledged more than $2 billion to combat the epidemic. The bureau of international Security and nonproliferation (ISN) is responsible for managing a broad range of U.S. nonproliferation policies, programs, agreements, and initiatives, and biological weapon is one their concerns Biosafety has its risks and benefits. All stakeholders must try to find a balance between cost-effectiveness of safety measures and use evidence-based safety practices and recommendations, measure the outcomes and consistently reevaluate the potential benefits that biosafety represents for human health. Biosafety level designations are based on a composite of the design features, construction, containment facilities, equipment, practices and operational procedures required for working with agents from the various risk groups.  Classification of biohazardous materials is subjective and the risk assessment is determined by the individuals most familiar with the specific characteristics of the organism. There are several factors taken into account when assessing an organism and the classification process.  See World Health Organization Biosafety Laboratory Guidelines: World Health Organization Biosafety Laboratory Guildlines  Investigations have shown that there are hundreds of unreported biosafety accidents, with laboratories self-policing the handling of biohazardous materials and lack of reporting. Poor record keeping, improper disposal, and mishandling biohazardous materials result in increased risks of biochemical contamination for both the public and environment.  Along with the precautions taken during the handling process of biohazardous materials, the World Health Organization recommends: Staff training should always include information on safe methods for highly hazardous procedures that are commonly encountered by all laboratory personnel and which involve:

Policy and practice in the United States.

Legal information.

In June 2009, the Trans-Federal Task Force On Optimizing Biosafety and Biocontainment Oversight recommended the formation of an agency to coordinate high safety risk level labs (3 and 4), and voluntary, non-punitive measures for incident reporting. However, it is unclear as to what changes may or may not have been implemented following their recommendations.

United States Code of Federal Regulations.

The United States Code of Federal Regulations is the codification (law), or collection of laws specific to a specific to a jurisdiction that represent broad areas subject to federal regulation. Title 42 of the Code of Federal Regulations addresses laws concerning Public Health issues including biosafety which can be found under the citation 42 CFR 73 to 42 CFR 73.21 by accessing the US Code of Federal Regulations (CFR) website.  Title 42 Section 73 of the CFR addresses specific aspects of biosafety including Occupational safety and health, transportation of biohazardous materials and safety plans for laboratories using potential biohazards. While biocontainment, as defined in the Biosafety in Microbiological and Biomedical Laboratories and Primary Containment for Biohazards: Selection, Installation and Use of Biosafety Cabinets manuals available at the Centers for Disease Control and Prevention website much of the design, implementation and monitoring of protocols are left up to state and local authorities. The United States CFR states "An individual or entity required to register [as a user of biological agents] must develop and implement a written biosafety plan that is commensurate with the risk of the select agent or toxin" which is followed by 3 recommended sources for laboratory reference.  While clearly the needs of biocontainment and biosafety measures vary across government, academic and private industry laboratories, biological agents pose similar risks independent of their locale. Laws relating to biosafety are not easily accessible and there are few federal regulations that are readily available for a potential trainee to reference outside of the publications recommended in 42 CFR 73.12. Therefore, training is the responsibility of lab employers and is not consistent across various laboratory types thereby increasing the risk of accidental release of biological hazards that pose serious health threats to the humans, animals and the ecosystem as a whole.

Agency guidance.

Many government agencies have made guidelines and recommendations in an effort to increase biosafety measures across laboratories in the United States. Agencies involved in producing policies surrounding biosafety within a hospital, pharmacy or clinical research laboratory include: the CDC, FDA, USDA, DHHS, DoT, EPA and potentially other local organizations including public health departments. The federal government does set some standards and recommendations for States to meet their standards, most of which fall under the Occupational Safety and Health Act of 1970. but currently, there is no single federal regulating agency directly responsible for ensuring the safety of biohazardous handling, storage, identification, clean-up and disposal. In addition to the CDC, the Environmental Protection Agency has some of the most accessible information on ecological impacts of biohazards, how to handle spills, reporting guidelines and proper disposal of agents dangerous to the environment. Many of these agencies have their own manuals and guidance documents relating to training and certain aspects of biosafety directly tied to their agency's scope, including transportation, storage and handling of blood borne pathogens. (OSHA, IATA). The American Biological Safety Association (ABSA) has a list of such agencies and links to their websites, along with links to publications and guidance documents to assist in risk assessment, lab design and adherence to laboratory exposure control plans. Many of these agencies were members of the 2009 Task Force on BioSafety. There was also a formation of a Blue Ribbon Study Panel on Biodefense, but this is more concernend with national defense programs and biosecurity.  Ultimately states and local governments, as well as private industry labs, are left to make the final determinants for their own biosafety programs, which vary widely in scope and enforcement across the United States. Not all state programs address biosafety from all necessary perspectives, which should not just include personal safety, but also emphasize an full understanding among laboratory personnel of quality control and assurance, exposure potential impacts on the environment, and general public safety.  Toby Ord puts into question whether the current international conventions regarding biotechnology research and development regulation, and self-regulation by biotechnology companies and the scientific community are adequate.  State occupational safety plans are often focused on transportation, disposal, and risk assessment, allowing caveats for safety audits, but ultimately leaves the training in the hands of the employer. 22 states have approved Occupational Safety plans by OSHA that are audited annually for effectiveness. These plans apply to private and public sector workers, and not necessarily state/ government workers, and not all specifically have a comprehensive program for all aspects of biohazard management from start to finish. Sometimes biohazard management plans are limited only to workers in transportation specific job titles. The enforcement and training on such regulations can vary from lab to lab based on the State's plans for occupational health and safety. With the exception of DoD lab personnel, CDC lab personnel, First responders, and DoT employees, enforcement of training is inconsistent, and while training is required to be done, specifics on the breadth and frequency of refresher training does not seem consistent from state to state; penalties may never be assessed without larger regulating bodies being aware of non-compliance, and enforcement is limited.

Medical waste management in the United States.

Medical waste management was identified as an issue in the 1980s; with the Medical Waste Tracking Act of 1988 becoming the new standard in biohazard waste disposal.  Although the Federal Government, EPA & DOT provide some oversight of regulated medical waste storage, transportation, and disposal the majority of biohazard medical waste is regulated at the state level. Each state is responsible for regulation and management of their own bioharzardous waste with each state varying in their regulatory process. Record keeping of biohazardous waste also varies between states.  Medical healthcare centers, hospitals veterinary clinics, clinical laboratories and other facilities generate over one million tons of waste each year. Although the majority of this waste is as harmless as common household waste, as much as 15 percent of this waste poses a potential infection hazard, according to the Environmental Protection Agency (EPA). Medical waste is required to be rendered non-infectious before it can be disposed of. There are several different methods to treat and dispose of biohazardous waste. In the United States, the primary methods for treatment and disposal of biohazard, medical and sharps waste may include:  Different forms of biohazardous wasted required different treatments for their proper waste management. This is determined largely be each states regulations. Currently, there are several contracted companies that focus on medical, sharps and biological hazard disposal. Stericycle and Daniels Health are two national leaders in medical waste and pharmaceutical disposal in the United States.

Incidents of non-compliance and reform efforts.

The United States Government has made it clear that biosafety is to be taken very seriously. In 2014, incidents with Anthrax and Ebola pathogens in CDC laboratories (), prompted the CDC director Tom Frieden to issue a moratorium for research with these types of select agents. An investigation concluded that there was a lack of adherence to safety protocols and "inadequate safeguards" in place. This indicated a lack of proper training or reinforcement of training and supervision on regular basis for lab personnel.  Following these incidents, the CDC established an "External Laboratory Safety Workgroup" (ELSW), and suggestions have been made to reform effectiveness of the Federal Select Agent Program. The White House issued a report on national biosafety priorities in 2015, outlining next steps for a national biosafety and security program, and addressed biological safety needs for health research, national defense, and public safety.  In 2016, the Association of Public Health Laboratories (APHL) had a presentation at their annual meeting focused on improving biosafety culture. This same year, The UPMC Center for Health Security issued a case study report including reviews of ten different nations' current biosafety regulations, including the United States. Their goal was to "provide a foundation for identifying national‐level biosafety norms and enable initial assessment of biosafety priorities necessary for developing effective national biosafety regulation and oversight."

Biosafety is the prevention of large-scale loss of biological integrity, focusing both on ecology and human health. These prevention mechanisms include conduction of regular reviews of the biosafety in laboratory settings, as well as strict guidelines to follow. Biosafety is used to protect from harmful incidents. Many laboratories handling biohazards employ an ongoing risk management assessment and enforcement process for biosafety. Failures to follow such protocols can lead to increased risk of exposure to biohazards or pathogens. Human error and poor technique contribute to unnecessary exposure and compromise the best safeguards set into place for protection.

La notion de « sûreté biologique » est polysémique (elle peut avoir plusieurs sens). De manière générale la sûreté biologique évoque les mesures à prendre pour sécuriser un patrimoine biologique (qui - selon le contexte - peut être réduit à l'agriculture, à la sylviculture, à la santé humaine ou étendu plus largement jusqu'à la biosphère).


Historical origin.

In May 1974, Vint Cerf and Bob Kahn described an internetworking protocol for sharing resources using packet switching among network nodes. The authors had been working with to incorporate concepts from the French CYCLADES project into the new network. The specification of the resulting protocol, ("Specification of Internet Transmission Control Program"), was written by Vint Cerf, Yogen Dalal, and Carl Sunshine, and published in December 1974. It contains the first attested use

Network function.

The Transmission Control Protocol provides a communication service at an intermediate level between an application program and the Internet Protocol. It provides host-to-host connectivity at the transport layer of the Internet model. An application does not need to know the particular mechanisms for sending data via a link to another host, such as the required IP fragmentation to accommodate the maximum transmission unit of the transmission medium. At the transport layer, TCP handles all handshaking and transmission details and presents an abstraction of the network connection to the application typically through a network socket interface.  At the lower levels of the protocol stack, due to network congestion, traffic load balancing, or unpredictable network behaviour, IP packets may be lost, duplicated, or delivered out of order. TCP detects these problems, requests re-transmission of lost data, rearranges out-of-order data and even helps minimize network congestion to reduce the occurrence of the other problems. If the data still remains undelivered, the source is notified of this failure. Once the TCP receiver has reassembled the sequence of octets originally transmitted, it passes them to the receiving application. Thus, TCP abstracts the application's communication from the underlying networking details.  TCP is used extensively by many internet applications, including the World Wide Web (WWW), email,

TCP segment structure.

Transmission Control Protocol accepts data from a data stream, divides it into chunks, and adds a TCP header creating a TCP segment. The TCP segment is then encapsulated into an Internet Protocol (IP) datagram, and exchanged with peers.  The term "TCP packet" appears in both informal and formal usage, whereas in more precise terminology "segment" refers to the TCP protocol data unit (PDU), "datagram" to the IP PDU, and "frame" to the data link layer PDU: Processes transmit data by

Protocol operation.

TCP protocol operations may be divided into three phases. Connections must be properly established in a multi-step handshake process ("connection establishment") before entering the "data transfer" phase. After data transmission is completed, the "connection termination" closes established virtual circuits and releases all allocated resources.  A TCP connection is managed by an operating system through a resource that represents the local end-point for communications, the "Internet socket". During the lifetime of a TCP connection, the local end-point undergoes a series of state changes:

Connection establishment.

To establish a connection, TCP uses a three-way handshake.  Before a client attempts to connect with a server, the server must first bind to and listen at a port to open it up for connections: this is called a passive open. Once the passive open is established, a

Connection termination.

The connection termination phase uses a four-way handshake, with each side of the connection terminating independently. When an endpoint wishes to stop its half of the connection, it transmits a FIN packet, which the other end acknowledges with an ACK. Therefore, a typical tear-down requires a pair of FIN and ACK segments from each TCP endpoint. After the side that sent the first FIN has responded with the final ACK, it waits for a timeout before finally closing the connection, during which time the local port is unavailable for new connections; this prevents confusion due to delayed packets being delivered during subsequent connections.  A connection can be "half-open", in which case one side has terminated its end, but the other has not. The side that has terminated can no longer send any data into the connection, but the other side can.

Resource usage.

Most implementations allocate an entry in a table that maps a session to a running operating system process. Because TCP packets do not include a session identifier, both endpoints identify the session using the client's address and port. Whenever a packet is received, the TCP implementation must perform a lookup on this table to find the destination process. Each entry in the table is known as a Transmission Control Block or TCB. It contains information about the endpoints (IP and port), status

Data transfer.

The Transmission Control Protocol differs in several key features from the User Datagram Protocol:

Reliable transmission.

TCP uses a "sequence number" to identify each byte of data. The sequence number identifies the order of the bytes sent from each computer so that the data can be reconstructed in order, regardless of any packet reordering, or packet loss that may occur during transmission. The sequence number of the first byte is chosen by the transmitter for the first packet, which is flagged SYN. This number can be arbitrary, and should, in fact, be unpredictable to defend against TCP sequence prediction attacks.  Acknowledgements (ACKs) are sent with a sequence number by the receiver of data to tell the sender that data has been received to the specified byte. ACKs do not imply that the data has been delivered to the application. They merely signify that it is now the receiver's responsibility to deliver the data.  Reliability is achieved by the sender detecting lost data and retransmitting it. TCP uses two primary techniques to identify loss. Retransmission timeout (abbreviated as RTO) and duplicate cumulative acknowledgements (DupAcks).

Error detection.

Sequence numbers allow receivers to discard duplicate packets and properly sequence reordered packets. Acknowledgments allow senders to determine when to retransmit lost packets.  To assure correctness a checksum field is included; see checksum computation section for details on checksumming. The TCP checksum is a weak check by modern standards. Data Link Layers with high bit error

Flow control.

TCP uses an end-to-end flow control protocol to avoid having the sender send data too fast for the TCP receiver to receive and process it reliably. Having a mechanism for flow control is essential in an environment where machines of diverse network speeds communicate. For example, if a PC sends data to a smartphone that is slowly processing received data, the smartphone must regulate the data flow so as not to be overwhelmed.  TCP uses a sliding window flow control protocol. In each TCP segment, the receiver specifies in the "receive window" field the amount of additionally received data (in bytes) that it is willing to buffer for the connection. The sending

Congestion control.

The final main aspect of TCP is congestion control. TCP uses a number of mechanisms to achieve high performance and avoid congestion collapse, where network performance can fall by several orders of magnitude. These mechanisms control the rate of data entering the network, keeping the data flow below a rate that would trigger collapse. They also yield an approximately max-min fair allocation between flows.  Acknowledgments for data sent, or lack of acknowledgments, are used by senders to infer network conditions between the TCP sender and receiver. Coupled with timers, TCP senders and receivers can alter the behavior of the flow of data. This is more generally referred to as congestion control and/or

Maximum segment size.

The maximum segment size (MSS) is the largest amount of data, specified in bytes, that TCP is willing to receive in a single segment. For best performance, the MSS should be set small enough to avoid IP fragmentation, which can lead to packet loss and excessive retransmissions. To try to accomplish this, typically the MSS is announced by each side using the MSS option when the TCP connection is established, in which case it is derived from the maximum transmission unit (MTU) size of the data link layer of the networks to which the sender and receiver are

Selective acknowledgments.

Relying purely on the cumulative acknowledgment scheme employed by the original TCP protocol can lead to inefficiencies when packets are lost. For example, suppose bytes with sequence number 1,000 to 10,999 are sent in 10 different TCP segments of equal size, and the second segment (sequence numbers 2,000 to 2,999) is lost during transmission. In a pure cumulative acknowledgment protocol, the receiver can only send a cumulative ACK value of 2,000 (the sequence number immediately following the last sequence number of the received data) and cannot say that it received bytes 3,000 to 10,999 successfully. Thus the sender may then have to resend all data starting with sequence number 2,000.  To alleviate this issue TCP employs the "selective acknowledgment (SACK)" option, defined in 1996 in RFC 2018, which allows the receiver to acknowledge discontinuous blocks of packets which were received correctly, in addition to the sequence number immediately following the last sequence number of the last contiguous byte received successively, as in the basic

Window scaling.

For more efficient use of high-bandwidth networks, a larger TCP window size may be used. The TCP window size field controls the flow of data and its value is limited to between 2 and 65,535 bytes.  Since the size field cannot be expanded, a scaling factor is used. The TCP window scale option, as defined in RFC 1323, is an option used to increase the maximum window size from 65,535 bytes to 1 gigabyte. Scaling up to larger window

TCP timestamps.

TCP timestamps, defined in RFC 1323 in 1992, can help TCP determine in which order packets were sent. TCP timestamps are not normally aligned to the system clock and start at some random value. Many operating systems will increment the timestamp for every elapsed millisecond; however the RFC only states that the ticks should be proportional.  There are two timestamp fields:  TCP timestamps are used in an algorithm known as "Protection Against Wrapped Sequence" numbers, or "PAWS" (see RFC

Out-of-band data.

It is possible to interrupt or abort the queued stream instead of waiting for the stream to finish. This is done by specifying the data as "urgent". This tells the receiving program to process it immediately, along with the rest of the urgent data. When finished, TCP informs the application and resumes back to the stream queue. An example is when TCP is used for a remote login session, the user can send a keyboard sequence that interrupts or aborts

Forcing data delivery.

Normally, TCP waits for 200 ms for a full packet of data to send (Nagle's Algorithm tries to group small messages into a single packet). This wait creates small, but potentially serious delays if repeated constantly during a file transfer. For example, a typical send block would be 4 KB, a typical MSS is 1460, so 2 packets go out on a 10 Mbit/s ethernet taking ~1.2 ms each followed by a third carrying the remaining 1176 after a 197 ms

Vulnerabilities.

TCP may be attacked in a variety of ways. The results of a thorough security assessment of TCP, along with possible mitigations for the identified issues, were published in 2009, and is currently being pursued within the IETF.

Denial of service.

By using a spoofed IP address and repeatedly sending purposely assembled SYN packets, followed by many ACK packets, attackers can cause the server to consume large amounts of resources keeping track of the bogus connections. This is known as a

Connection hijacking.

An attacker who is able to eavesdrop a TCP session and redirect packets can hijack a TCP connection. To do so, the attacker learns the sequence number from the ongoing communication and forges a false segment that looks like the next segment in the stream. Such a simple hijack can result in one packet being erroneously accepted at one end. When the receiving host acknowledges the extra segment to the other side of the connection, synchronization is lost. Hijacking might

TCP veto.

An attacker who can eavesdrop and predict the size of the next packet to be sent can cause the receiver to accept a malicious payload without disrupting the existing connection. The attacker injects a malicious packet with the sequence number and a payload size of the next expected packet. When the legitimate packet is ultimately received, it is found to have the same sequence number and length as a packet already received

TCP ports.

TCP and UDP use port numbers to identify sending and receiving application end-points on a host, often called Internet sockets. Each side of a TCP connection has an associated 16-bit unsigned port number (0-65535) reserved by the sending or receiving application. Arriving TCP packets are identified as belonging to a specific TCP connection by its sockets, that is, the combination of source host address, source port, destination host address, and destination port. This means that a server computer can provide several clients with several services simultaneously, as long as a client takes care of initiating any simultaneous connections to one destination port from different source ports.  Port numbers are categorized into three basic categories: well-known, registered, and dynamic/private. The

Development.

TCP is a complex protocol. However, while significant enhancements have been made and proposed over the years, its most basic operation has not changed significantly since its first specification RFC 675 in 1974, and the v4 specification RFC 793, published in September 1981. RFC 1122, Host Requirements for Internet Hosts, clarified a number of TCP protocol implementation requirements. A list of the 8 required specifications and over 20 strongly encouraged enhancements is available in RFC 7414. Among this list is RFC 2581, TCP Congestion Control, one of the most important TCP-related RFCs in recent years, describes updated algorithms that avoid undue congestion. In 2001, RFC 3168 was written to describe Explicit Congestion Notification (ECN), a congestion avoidance signaling mechanism.  The original TCP congestion avoidance algorithm was known as "TCP Tahoe", but many alternative algorithms have since been proposed (including TCP Reno, TCP Vegas, FAST TCP, TCP New Reno, and TCP Hybla).  TCP Interactive (iTCP) is a research effort into TCP extensions that allows applications to subscribe to TCP events and register handler components that can launch applications for various purposes, including application-assisted congestion control.  Multipath TCP (MPTCP) is an ongoing effort within the IETF that aims at allowing a TCP connection

TCP over wireless networks.

TCP was originally designed for wired networks. Packet loss is considered to be the result of network congestion and the congestion window size is reduced dramatically as a precaution. However, wireless links are known to experience sporadic and usually temporary losses due to fading, shadowing, hand off, interference, and other radio effects, that are not strictly congestion. After the (erroneous) back-off of the congestion window size, due to

Hardware implementations.

One way to overcome the processing power requirements of TCP is to build hardware implementations of it, widely known as TCP offload engines (TOE).

Debugging.

A packet sniffer, which intercepts TCP traffic on a network link, can be useful in debugging networks, network stacks, and applications that use TCP by showing the user what packets are passing

Alternatives.

For many applications TCP is not appropriate. One problem (at least with normal implementations) is that the application cannot access the packets coming after a lost packet until the retransmitted copy of the lost packet is received. This causes problems for real-time applications such as streaming media, real-time multiplayer games and voice over IP (VoIP) where it is generally more useful to get most of the data in a timely fashion than it is to get all of the data in order.  For historical and performance reasons, most storage area networks (SANs) use Fibre Channel Protocol (FCP) over Fibre Channel connections.  Also, for embedded systems, network booting, and servers that serve simple requests from huge numbers of clients (e.g. DNS servers) the complexity of TCP can be a problem. Finally, some tricks such as transmitting data between two hosts that are both behind NAT (using STUN or similar systems) are far simpler without a relatively complex protocol like TCP in

Checksum computation.

TCP checksum for IPv4.

When TCP runs over IPv4, the method used to compute the checksum is defined in RFC 793:  "The checksum field is the 16 bit one's complement of the one's complement sum of all 16-bit words in the header and text. If a segment contains an odd number of header and text octets to be checksummed, the last octet is padded on the right with zeros to form a 16-bit word for checksum purposes.

TCP checksum for IPv6.

When TCP runs over IPv6, the method used to compute the checksum is changed,

Checksum offload.

Many TCP/IP software stack implementations provide options to use hardware assistance to automatically compute the checksum in the network adapter prior to transmission onto the network or upon reception from the network for validation. This may relieve the OS from using precious CPU cycles calculating the checksum. Hence, overall network performance is increased.  This feature may cause packet analyzers that are unaware or uncertain

The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is commonly referred to as "TCP/IP". TCP provides reliable, ordered, and error-checked delivery of a stream of octets (bytes) between applications running on hosts communicating via an IP network. Major internet applications such as the World Wide Web, email, remote administration, and file transfer rely on TCP, which is part of the Transport Layer of the TCP/IP suite. SSL/TLS often runs on top of TCP.

Dans le modèle Internet, aussi appelé modèle TCP/IP, TCP est situé au-dessus de IP. Dans le modèle OSI, il correspond à la couche transport, intermédiaire de la couche réseau et de la couche session. Les applications transmettent des flux de données sur une connexion réseau. TCP découpe le flux d’octets en "segments" dont la taille dépend de la MTU du réseau sous-jacent (couche liaison de données).


History and description.

The production of swords in Japan is divided into specific time periods: Authentic tachi were forged during the Kotō period, before 1596. The tachi preceded the "katana"; the latter was not mentioned by name to indicate a blade distinct from a tachi until near the end of the twelfth century. With a few exceptions, katana and tachi can be distinguished from each other if signed by the location of the signature ("mei") on the tang. In general the signature should be carved into the side of the tang that would face outward when the sword was worn on the wielder's left waist. Since a "tachi" was worn cutting edge down, and the "katana" was worn cutting edge up the "mei" would be in opposite locations on the tang of both types of swords.  An authentic tachi that was manufactured in the correct time period had an average cutting edge length () of 70–80 cm (– in) and compared to a katana was generally lighter in proportion to its length, had a greater taper from hilt to point, was more curved and had a smaller point area.  Unlike the traditional manner of wearing the katana, the tachi was worn hung from the belt with the cutting-edge down, and was most effective when used by cavalry. Deviations from the average length of tachi have the prefixes "ko-" for "short" and "ō-" for "great, large" attached. For instance, tachi that were "shōtō" and closer in size to a "wakizashi" were called "kodachi". The longest tachi (considered a 15th-century "ōdachi") in existence is more than in total length with a blade, but believed to be ceremonial. In the late 1500s and early 1600s many old surviving tachi blades were converted into katana by having their original tangs cut ("o-suriage"), which meant the signatures were removed from the swords.  For a sword to be worn in "tachi style" it needed to be mounted in a "tachi koshirae". The tachi koshirae had two hangers (ashi) which allowed the sword to be worn in a horizontal position with the cutting edge down. A sword not mounted in a tachi koshirae could be worn tachi style by use of a "koshiate", a leather device which would allow any sword to be worn in the tachi style.

Use.

According to author Karl F. Friday, before the 13th century there are no written references or drawings etc. that show swords of any kind were actually used while on horseback.  The "uchigatana" was derived from the tachi and was the predecessor to the katana as the battlesword of feudal Japan's "bushi" (warrior class), and as it evolved into the later design, the tachi and the uchigatana were often differentiated from each other only by how they were worn, the fittings for the blades, and the location of the signature (mei).  As a result of the first Mongol invasions of Japan in 1274, tachi started to be made thicker and wider.  In later Japanese feudal history, during the Sengoku and Edo periods, certain high-ranking warriors of what became the ruling class would wear their sword tachi-style (edge-downward), rather than with the scabbard thrust through the belt with the edge upward.  With the rising of statism in Shōwa Japan, the Imperial Japanese Army and the Imperial Japanese Navy implemented swords called shin and kaiguntō, which were worn tachi style (cutting edge down).

A was a type of traditionally made Japanese sword worn by the samurai class of feudal Japan. Tachi and katana generally differ in length, degree of curvature, and how they were worn when sheathed, the latter depending on the location of the "mei", or signature, on the tang. The tachi style of swords preceded the development of the katana, which was not mentioned by name until near the end of the twelfth century; tachi are known to have been made in the "Kotō" period, ranging from 900 to 1596.

Le tachi (太刀) est un sabre possédant une lame courbe d'environ, précurseur du sabre japonais classique. C'est principalement une arme de cavalerie.


History.

A mainly British phenomenon, the Teddy Boy subculture started among teenagers in London in the early 1950s, and rapidly spread across the UK, becoming strongly associated with American rock and roll music. After World War II, male youths in delinquent gangs who had adopted Edwardian-era fashion were sometimes known as Cosh Boys, but the name "Teddy Boy" was coined when a 23 September 1953 "Daily Express" newspaper report headline shortened "Edwardian" to "Teddy". Nevertheless, the term had previously been used in Edwardian England to refer to members of the Territorial Army (see for example "The Swoop!" written by P. G. Wodehouse in 1909).  In post-war Britain, rationing continued to affect the fashion industry, and men's tailors in central London devised a style based on Edwardian clothing hoping to sell to young officers being demobbed from the services. However, the style—featuring tapered trousers, long jackets similar to post-war American zoot suits, and fancy waistcoats—was not popular with its target market, leaving tailors with piles of unsold clothing which, to recoup losses, were sold cheaply to menswear shops elsewhere in London. While there had been some affluent adoption—"an extravagant upper-class snub to the post-war Labour Government and its message of austerity"—it was predominantly suburban working class youth who adopted and adapted the look ('spiv' and cosh boy associations also hastened its middle class rejection) and, around 1952, what became the 'Teddy Boy' style began to emerge, gradually spreading across Britain.  Although there had been youth groups with their own dress codes called scuttlers in 19th-century Manchester and Liverpool, Teddy Boys were the first youth group in Britain to differentiate themselves as teenagers, helping create a youth market. The US film "Blackboard Jungle" marked a watershed in the United Kingdom. When shown in an Elephant and Castle cinema, south London in 1956, the teenage Teddy boy audience began to riot, tearing up seats and dancing in the cinema's aisles. After that, other riots took place around the country where the film was shown.  Some Teds formed gangs and gained notoriety following violent clashes with rival youth gangs as well as unprovoked attacks on immigrants. The most notable clashes were the 1958 Notting Hill race riots, in which Teddy Boys were present in large numbers and were implicated in attacks on the West Indian community. According to reports released decades after the riots, "Teddy boys armed with iron bars, butcher's knives and weighted leather belts" participated in mobs "300- to 400-strong" that targeted Black residents, in one night alone leaving "five black men lying unconscious on the pavements of Notting Hill." The violent lifestyle was sensationalised in the pulp novel "Teddy Boy" by Ernest Ryman, first published in the UK in 1958.

Style.

Teddy Boy clothing included drape jackets reminiscent of 1940s American zoot suits worn by Italian-American, Chicano and African-American communities (such as Cab Calloway or Louis Jordan), usually in dark shades, sometimes with a velvet trim collar and pocket flaps, and high-waist "drainpipe" trousers, often exposing the socks. The outfit also included a high-necked loose-collared white shirt (known as a "Mr. B." collar, because it was often worn by jazz musician Billy Eckstine); a narrow "Slim Jim" tie or western bolo tie, and a brocade waistcoat. The clothes were mostly tailor-made at great expense, and paid through weekly installments.  Favoured footwear included highly polished Oxfords, chunky brogues, and crepe-soled shoes, often suede (known as brothel creepers or beetle crushers). Preferred hairstyles included long, strongly moulded greased-up hair with a quiff at the front and the side combed back to form a duck's arse at the rear. Another style was the "Boston", in which the hair was greased straight back and cut square across at the nape.

Teddy Girls.

Teddy Girls (also called Judies) wore drape jackets, pencil skirts, hobble skirts, long plaits, rolled-up jeans, flat shoes, tailored jackets with velvet collars, straw boater hats, cameo brooches, espadrilles, coolie hats and long, elegant clutch bags. Later, they adopted the American fashions of toreador pants, voluminous circle skirts, and hair in ponytails.  The Teddy Girls' choices of clothes were not intended strictly for aesthetic effect; these girls were collectively rejecting post-war austerity. They were young working-class women from the poorer districts of London. They would typically leave school at the age of 14 or 15 and work in factories or offices. Teddy Girls spent much of their free time buying or making their trademark clothes. Their style originated from a head-turning, fastidious style from the fashion houses, which had launched haute-couture clothing lines recalling the Edwardian era.  A photo shoot by Liz Ham titled "Teddy Girls" was published by Oyster in 2009 and then in "Art Monthly Australia" in 2010.

Music and dancing.

Although Teddy Boys became associated with rock and roll music, prior to the advent of that genre, Teddy Boys also listened and danced to jump blues, R&B, jazz and skiffle music. A well-known dance that the Teddy Boys adopted was "The Creep", a slow shuffle that was so popular with Teddy Boys that it led to their other nickname, "Creepers". The song "The Creep" came out in 1953 and was written and recorded for HMV by Yorkshire-born big band leader and saxophonist Ken Mackintosh. Although this was not a rock and roll record, it was widely taken on by the Teddy Boys of the time. From 1955, Rock and Roll was adopted by the Teddy Boys when the film "Blackboard Jungle" was first shown in cinemas in the UK, and Teddy Boys started listening to artists like Elvis Presley, Bill Haley and Eddie Cochran.  Although not as big as the Americans, British rock and roll artists such as Tommy Steele, Marty Wilde, Cliff Richard and Joe Brown became popular with the Teddy Boy culture, as did Merseybeat bands such as The Searchers, Gerry and the Pacemakers and The Beatles. Original rock and roll artists such as Billy Fury also moved to beat music.

Revivals.

George Harrison and John Lennon emulated the style in the early formation of the Beatles.  Later, following The London Rock and Roll Show held at Wembley Stadium in August 1972 (featuring American performers including Little Richard, Jerry Lee Lewis and Chuck Berry, plus UK-based support acts), the music enjoyed a renewed period of popularity. Musical momentum was maintained by the release of films such as "American Graffiti" and "That'll Be the Day" (both 1973) and glam rock reworkings by bands such as Wizzard, The Glitter Band and Showaddywaddy topping the pop charts from 1973.  Concurrently, a resurgence of interest in Teddy Boy fashions was promoted by Vivienne Westwood and Malcolm McLaren through their shop Let it Rock, on London's King's Road. The new generation of Teds adopted some aspects of the 1950s but with a large glam rock influence, including louder colours for drape jackets, brothel creepers and socks and shiny satin shirts worn with bootlace ties, jeans and big-buckled belts. The 1970s Teddy Boys often sported flamboyant pompadour hairstyles in addition to long sideburns and added hairspray to grease/pomade to style their hair. In the late 1970s, the new generation became the enemies of the Westwood and Sex Pistols-inspired punk rockers. In the spring of 1977, street battles between young punks and aging teds happened on London's King's Road, where the earliest new-wave shops, including Westwood and McLaren's "Sex" (by now not selling zoot suits and ted gear anymore), were situated. In the late 1980s, there was a move by a number of Teddy Boys to revive the 1950s Teddy Boy style. In the early 1990s, a group of Teddy Boy revivalists in the Tottenham area of north London formed "The Edwardian Drape Society" (T.E.D.S.). The group concentrated on reclaiming the style which they felt had become bastardised by pop/glam rock bands such as Showaddywaddy and Mud in the 1970s.

The Teddy Boys or Teds were a mainly British subculture of young men wearing clothes partly inspired by the styles worn by dandies in the Edwardian period, which Savile Row tailors had attempted to re-introduce in Britain after the Second World War.

Le mouvement des, issu de la sous-culture britannique des années 1950, était constitué de jeunes anglais (les Teddy Boys) portant des vêtements d'inspiration édouardienne et souvent considérés comme violents et durs. La ville de Londres en fut l'épicentre. La mode se répandit très vite à travers le Royaume-Uni et fut dès ses débuts associée au rock 'n' roll. Bien qu'il y eût déjà, au dix-neuvième siècle, à Manchester et à Liverpool, des bandes de jeunes, appelés "scuttlers", ayant leurs propres codes vestimentaires, les "Teddy Boys" furent les premiers à s'imposer comme, contribuant ainsi à l'émergence d'une culture de consommation propre à la jeunesse.