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Saturday, October 29, 2022

Nation state

From Wikipedia, the free encyclopedia
 
Portrait of "The Ratification of the Treaty of Münster", one of the treaties leading to the Peace of Westphalia, where the concept of the "nation state" was born.

A nation state is a political unit where the state and nation are congruent. It is a more precise concept than "country", since a country does not need to have a predominant ethnic group.

A nation, in the sense of a common ethnicity, may include a diaspora or refugees who live outside the nation state; some nations of this sense do not have a state where that ethnicity predominates. In a more general sense, a nation state is simply a large, politically sovereign country or administrative territory. A nation state may be contrasted with:

  • A multinational state, where no one ethnic group dominates (such a state may also be considered a multicultural state depending on the degree of cultural assimilation of various groups).
  • A city-state, which is both smaller than a "nation" in the sense of "large sovereign country" and which may or may not be dominated by all or part of a single "nation" in the sense of a common ethnicity.
  • An empire, which is composed of many countries (possibly non-sovereign states) and nations under a single monarch or ruling state government.
  • A confederation, a league of sovereign states, which might or might not include nation-states.
  • A federated state, which may or may not be a nation-state, and which is only partially self-governing within a larger federation (for example, the state boundaries of Bosnia and Herzegovina are drawn along ethnic lines, but those of the United States are not).

This article mainly discusses the more specific definition of a nation-state as a typically sovereign country dominated by a particular ethnicity.

Complexity

The relationship between a nation (in the ethnic sense) and a state can be complex. The presence of a state can encourage ethnogenesis, and a group with a pre-existing ethnic identity can influence the drawing of territorial boundaries or argue for political legitimacy.

This definition of a "nation-state" is not universally accepted. "All attempts to develop terminological consensus around "nation" resulted in failure", concludes academic Valery Tishkov.

Walker Connor discusses the impressions surrounding the characters of "nation", "(sovereign) state", "nation state", and "nationalism". Connor, who gave the term "ethnonationalism" wide currency, also discusses the tendency to confuse nation and state and the treatment of all states as if nation states.

History and origins

The origins and early history of nation states are disputed. A major theoretical question is: "Which came first, the nation or the nation state?" Scholars such as Steven Weber, David Woodward, Michel Foucault and Jeremy Black have advanced the hypothesis that the nation state did not arise out of political ingenuity or an unknown undetermined source, nor was it a political invention; but is an inadvertent byproduct of 15th-century intellectual discoveries in political economy, capitalism, mercantilism, political geography, and geography combined with cartography and advances in map-making technologies. It was with these intellectual discoveries and technological advances that the nation state arose. For others, the nation existed first, then nationalist movements arose for sovereignty, and the nation state was created to meet that demand. Some "modernization theories" of nationalism see it as a product of government policies to unify and modernize an already existing state. Most theories see the nation state as a 19th-century European phenomenon, facilitated by developments such as state-mandated education, mass literacy and mass media. However, historians also note the early emergence of a relatively unified state and identity in Portugal and the Dutch Republic.

In France, Eric Hobsbawm argues, the French state preceded the formation of the French people. Hobsbawm considers that the state made the French nation, not French nationalism, which emerged at the end of the 19th century, the time of the Dreyfus Affair. At the time of the 1789 French Revolution, only half of the French people spoke some French, and 12–13% spoke the version of it that was to be found in literature and in educational facilities, according to Hobsbawm.

During the Italian unification, the number of people speaking the Italian language was even lower. The French state promoted the replacement of various regional dialects and languages by a centralised French language, and so did, and still does, Italy. The introduction of conscription and the Third Republic's 1880s laws on public instruction facilitated the creation of a national identity under this theory.

The Revolutions of 1848 were democratic and liberal in nature, with the aim of removing the old monarchical structures and creating independent nation-states.

Some nation states, such as Germany and Italy, came into existence at least partly as a result of political campaigns by nationalists, during the 19th century. In both cases, the territory was previously divided among other states, some of them very small. The sense of common identity was at first a cultural movement, such as in the Völkisch movement in German-speaking states, which rapidly acquired a political significance. In these cases, the nationalist sentiment and the nationalist movement clearly precede the unification of the German and Italian nation states.

Historians Hans Kohn, Liah Greenfeld, Philip White and others have classified nations such as Germany or Italy, where cultural unification preceded state unification, as ethnic nations or ethnic nationalities. However, "state-driven" national unifications, such as in France, England or China, are more likely to flourish in multiethnic societies, producing a traditional national heritage of civic nations, or territory-based nationalities.

The idea of a nation state was and is associated with the rise of the modern system of states, often called the "Westphalian system" in reference to the Treaty of Westphalia (1648). The balance of power, which characterized that system, depended on its effectiveness upon clearly defined, centrally controlled, independent entities, whether empires or nation states, which recognize each other's sovereignty and territory. The Westphalian system did not create the nation state, but the nation state meets the criteria for its component states (by assuming that there is no disputed territory). Before the Westphalian system, the closest geopolitical system was the "Chanyuan system" established in East Asia in 1005 through the Treaty of Chanyuan, which, like the Westphalian peace treaties, designated national borders between the independent regimes of China's Song dynasty and the nomadic Liao dynasty. This system was copied and developed in East Asia in the following centuries until the establishment of the pan-Eurasian Mongol Empire in the 13th century.

The nation state received a philosophical underpinning in the era of Romanticism, at first as the "natural" expression of the individual peoples (romantic nationalism: see Johann Gottlieb Fichte's conception of the Volk, later opposed by Ernest Renan). The increasing emphasis during the 19th century on the ethnic and racial origins of the nation, led to a redefinition of the nation state in these terms. Racism, which in Boulainvilliers's theories was inherently antipatriotic and antinationalist, joined itself with colonialist imperialism and "continental imperialism", most notably in pan-Germanic and pan-Slavic movements.

The relation between racism and ethnic nationalism reached its height in the 20th century fascism and Nazism. The specific combination of "nation" ("people") and "state" expressed in such terms as the Völkische Staat and implemented in laws such as the 1935 Nuremberg laws made fascist states such as early Nazi Germany qualitatively different from non-fascist nation states. Minorities were not considered part of the people (Volk), and were consequently denied to have an authentic or legitimate role in such a state. In Germany, neither Jews nor the Roma were considered part of the people and both were specifically targeted for persecution. German nationality law defined "German" on the basis of German ancestry, excluding all non-Germans from the people.

In recent years, a nation state's claim to absolute sovereignty within its borders has been criticized. A global political system based on international agreements and supra-national blocs characterized the post-war era. Non-state actors, such as international corporations and non-governmental organizations, are widely seen as eroding the economic and political power of nation states.

According to Andreas Wimmer and Yuval Feinstein, nation-states tended to emerge when power shifts allowed nationalists to overthrow existing regimes or absorb existing administrative units. Xue Li and Alexander Hicks links the frequency of nation-state creation to processes of diffusion that emanate from international organizations.

Before the nation state

Dissolution of the multiethnic Austro-Hungarian Empire (1918)

In Europe, during the 18th century, the classic non-national states were the multiethnic empires, the Austrian Empire, the Kingdom of France (and its empire), the Kingdom of Hungary, the Russian Empire, the Portuguese Empire, the Spanish Empire, the Ottoman Empire, the British Empire, the Dutch Empire and smaller nations at what would now be called sub-state level. The multi-ethnic empire was an absolute monarchy ruled by a king, emperor or sultan. The population belonged to many ethnic groups, and they spoke many languages. The empire was dominated by one ethnic group, and their language was usually the language of public administration. The ruling dynasty was usually, but not always, from that group.

This type of state is not specifically European: such empires existed in Asia, Africa and the Americas. Chinese dynasties, such as the Tang dynasty, the Ming dynasty, and the Qing dynasty, were all multiethnic regimes governed by a ruling ethnic group. In the three examples, their ruling ethnic groups were the Turks, the Han-Chinese, and the Manchus, respectively. In the Muslim world, immediately after Muhammad's death in 632, Caliphates were established. Caliphates were Islamic states under the leadership of a political-religious successor to the Islamic prophet Muhammad. These polities developed into multi-ethnic trans-national empires. The Ottoman sultan, Selim I (1512–1520) reclaimed the title of caliph, which had been in dispute and asserted by a diversity of rulers and "shadow caliphs" in the centuries of the Abbasid-Mamluk Caliphate since the Mongols' sacking of Baghdad and the killing of the last Abbasid Caliph in Baghdad, Iraq 1258. The Ottoman Caliphate as an office of the Ottoman Empire was abolished under Mustafa Kemal Atatürk in 1924 as part of Atatürk's Reforms.

Some of the smaller European states were not so ethnically diverse, but were also dynastic states, ruled by a royal house. Their territory could expand by royal intermarriage or merge with another state when the dynasty merged. In some parts of Europe, notably Germany, very small territorial units existed. They were recognized by their neighbors as independent, and had their own government and laws. Some were ruled by princes or other hereditary rulers, some were governed by bishops or abbots. Because they were so small, however, they had no separate language or culture: the inhabitants shared the language of the surrounding region.

In some cases, these states were simply overthrown by nationalist uprisings in the 19th century. Liberal ideas of free trade played a role in German unification, which was preceded by a customs union, the Zollverein. However, the Austro-Prussian War, and the German alliances in the Franco-Prussian War, were decisive in the unification. The Austro-Hungarian Empire and the Ottoman Empire broke up after the First World War, and the Russian Empire became the Soviet Union after the Russian Civil War.

A few of the smaller states survived: the independent principalities of Liechtenstein, Andorra, Monaco, and the republic of San Marino. (Vatican City is a special case. All of the larger Papal States save the Vatican itself were occupied and absorbed by Italy by 1870. The resulting Roman Question was resolved with the rise of the modern state under the 1929 Lateran treaties between Italy and the Holy See.)

Characteristics

"Legitimate states that govern effectively and dynamic industrial economies are widely regarded today as the defining characteristics of a modern nation-state."

Nation states have their own characteristics, differing from those of the pre-national states. For a start, they have a different attitude to their territory when compared with dynastic monarchies: it is semisacred and nontransferable. No nation would swap territory with other states simply, for example, because the king's daughter married. They have a different type of border, in principle defined only by the area of settlement of the national group, although many nation states also sought natural borders (rivers, mountain ranges). They are constantly changing in population size and power because of the limited restrictions of their borders.

The most noticeable characteristic is the degree to which nation states use the state as an instrument of national unity, in economic, social and cultural life.

The nation state promoted economic unity, by abolishing internal customs and tolls. In Germany, that process, the creation of the Zollverein, preceded formal national unity. Nation states typically have a policy to create and maintain a national transportation infrastructure, facilitating trade and travel. In 19th-century Europe, the expansion of the rail transport networks was at first largely a matter for private railway companies, but gradually came under control of the national governments. The French rail network, with its main lines radiating from Paris to all corners of France, is often seen as a reflection of the centralised French nation state, which directed its construction. Nation states continue to build, for instance, specifically national motorway networks. Specifically transnational infrastructure programmes, such as the Trans-European Networks, are a recent innovation.

The nation states typically had a more centralised and uniform public administration than its imperial predecessors: they were smaller, and the population less diverse. (The internal diversity of the Ottoman Empire, for instance, was very great.) After the 19th-century triumph of the nation state in Europe, regional identity was subordinate to national identity, in regions such as Alsace-Lorraine, Catalonia, Brittany and Corsica. In many cases, the regional administration was also subordinated to central (national) government. This process was partially reversed from the 1970s onward, with the introduction of various forms of regional autonomy, in formerly centralised states such as Spain or Italy.

The most obvious impact of the nation state, as compared to its non-national predecessors, is the creation of a uniform national culture, through state policy. The model of the nation state implies that its population constitutes a nation, united by a common descent, a common language and many forms of shared culture. When the implied unity was absent, the nation state often tried to create it. It promoted a uniform national language, through language policy. The creation of national systems of compulsory primary education and a relatively uniform curriculum in secondary schools, was the most effective instrument in the spread of the national languages. The schools also taught the national history, often in a propagandistic and mythologised version, and (especially during conflicts) some nation states still teach this kind of history.

Language and cultural policy was sometimes negative, aimed at the suppression of non-national elements. Language prohibitions were sometimes used to accelerate the adoption of national languages and the decline of minority languages (see examples: Anglicisation, Bulgarization, Croatization, Czechization, Dutchification, Francisation, Germanisation, Hellenization, Hispanicization, Italianization, Lithuanization, Magyarisation, Polonisation, Russification, Serbization, Slovakisation, Swedification, Turkification).

In some cases, these policies triggered bitter conflicts and further ethnic separatism. But where it worked, the cultural uniformity and homogeneity of the population increased. Conversely, the cultural divergence at the border became sharper: in theory, a uniform French identity extends from the Atlantic coast to the Rhine, and on the other bank of the Rhine, a uniform German identity begins. To enforce that model, both sides have divergent language policy and educational systems.

In practice

The notion of a unifying "national identity" also extends to countries that host multiple ethnic or language groups, such as India. For example, Switzerland is constitutionally a confederation of cantons, and has four official languages, but it has also a "Swiss" national identity, a national history and a classic national hero, Wilhelm Tell.

Innumerable conflicts have arisen where political boundaries did not correspond with ethnic or cultural boundaries.

After World War II in the Josip Broz Tito era, nationalism was appealed to for uniting South Slav peoples. Later in the 20th century, after the break-up of the Soviet Union, leaders appealed to ancient ethnic feuds or tensions that ignited conflict between the Serbs, Croats and Slovenes, as well as Bosniaks, Montenegrins and Macedonians, eventually breaking up the long collaboration of peoples. Ethnic cleansing was carried out in the Balkans, resulting in the destruction of the formerly socialist republic and producing the civil wars in Croatia and Bosnia and Herzegovina in 1992–95, resulting in mass population displacements and segregation that radically altered what was once a highly diverse and intermixed ethnic makeup of the region. These conflicts were largely about creating a new political framework of states, each of which would be ethnically and politically homogeneous. Serbs, Croats and Bosniaks insisted they were ethnically distinct although many communities had a long history of intermarriage. Presently Croatia (90,42%), Slovenia (83,1-88%) and Serbia (83,3% Serb) could be classified as monoethnic states, whereas North Macedonia (66% Macedonian), Montenegro (42% Montenegrin) and Bosnia and Herzegovina (50.1% Bosniak) are multiethnic states.

Belgium is a classic example of a state that is not a nation state. The state was formed by secession from the United Kingdom of the Netherlands in 1830, whose neutrality and integrity was protected by the Treaty of London 1839; thus it served as a buffer state after the Napoleonic Wars between the European powers France, Prussia (after 1871 the German Empire) and the United Kingdom until World War I, when its neutrality was breached by the Germans. Currently, Belgium is divided between the Flemings in the north, the French-speaking population in the south, and the German-speaking population in the east. The Flemish population in the north speaks Dutch, the Walloon population in the south speaks either French or, in the east of Liège Province, German. The Brussels population speaks French or Dutch.

The Flemish identity is also cultural, and there is a strong separatist movement espoused by the political parties, the right-wing Vlaams Belang and the Nieuw-Vlaamse Alliantie. The Francophone Walloon identity of Belgium is linguistically distinct and regionalist. There is also unitary Belgian nationalism, several versions of a Greater Netherlands ideal, and a German-speaking community of Belgium annexed from Germany in 1920, and re-annexed by Germany in 1940–1944. However, these ideologies are all very marginal and politically insignificant during elections.

Ethnolinguistic map of mainland China and Taiwan

China covers a large geographic area and uses the concept of "Zhonghua minzu" or Chinese nationality, in the sense of ethnic groups, but it also officially recognizes the majority Han ethnic group which accounts for over 90% of the population, and no fewer than 55 ethnic national minorities.

According to Philip G. Roeder, Moldova is an example of a Soviet era "segment-state" (Moldavian SSR), where the "nation-state project of the segment-state trumped the nation-state project of prior statehood. In Moldova, despite strong agitation from university faculty and students for reunification with Romania, the nation-state project forged within the Moldavian SSR trumped the project for a return to the interwar nation-state project of Greater Romania." See Controversy over linguistic and ethnic identity in Moldova for further details.

Exceptional cases

Israel

Israel was founded as a Jewish state in 1948. Its "Basic Laws" describe it as both a Jewish and a democratic state. The Basic Law: Israel as the Nation-State of the Jewish People (2018) explicitly specifies the nature of the State of Israel as the nation-state of the Jewish people. According to the Israel Central Bureau of Statistics, 75.7% of Israel's population are Jews. Arabs, who make up 20.4% of the population, are the largest ethnic minority in Israel. Israel also has very small communities of Armenians, Circassians, Assyrians, Samaritans. There are also some non-Jewish spouses of Israeli Jews. However, these communities are very small, and usually number only in the hundreds or thousands.

Kingdom of the Netherlands

The Kingdom of the Netherlands presents an unusual example in which one kingdom represents four distinct countries. The four countries of the Kingdom of the Netherlands are:

Each is expressly designated as a land in Dutch law by the Charter for the Kingdom of the Netherlands. Unlike the German Länder and the Austrian Bundesländer, landen is consistently translated as "countries" by the Dutch government.

Pakistan

Pakistan, even being an ethnically diverse country and officially a federation, is regarded as a nation state due to its ideological basis on which it was given independence from British India as a separate nation rather than as part of a unified India. Different ethnic groups in Pakistan are strongly bonded by their common Muslim identity, common cultural and social values, common historical heritage, a national lingua franca (Urdu) and joint political, strategic and economic interests.

Spain

While historical monarchies often brought together different kingdoms/territories/ethnic groups under the same crown, in modern nation states political elites seek a uniformity of the population, leading to state nationalism. In the case of the Christian territories of the future Spain, neighboring Al-Andalus, there was an early perception of ethnicity, faith and shared territory in the Middle Ages (13th-14th centuries), as documented by the Chronicle of Muntaner in the proposal of the Castilian king to the other Christian kings of the peninsula: "...if these four Kings of Spain whom he named, who are of one flesh and blood, held together, little need they fear all the other powers of the world...". After the dynastic union of the Catholic Monarchs in the 15th century, the Spanish Monarchy ruled over different kingdoms, each with its own cultural, linguistic and political particularities, and the kings had to swear by the Laws of each territory before the respective Parliaments.

After the War of the Spanish Succession, rooted in the political position of the Count-Duke of Olivares and the absolutism of Philip V, the assimilation of the Crown of Aragon by the Castilian Crown through the Decrees of Nova planta was the first step in the creation of the Spanish nation-state. As in other contemporary European states, political union was the first step in the creation of the Spanish nation-state, in this case not on a uniform ethnic basis, but through the imposition of the political and cultural characteristics of the dominant ethnic group, in this case the Castilians, over those of other ethnic groups, who became national minorities to be assimilated. In fact, since the political unification of 1714, Spanish assimilation policies towards Catalan-speaking territories (Catalonia, Valencia, the Balearic Islands, part of Aragon) and other national minorities have been a historical constant.

School map of Spain from 1850. On it, the State is shown divided into four parts:- "Fully constitutional Spain", which includes Castile and Andalusia, but also the Galician-speaking territories. - "Annexed or assimilated Spain": the territories of the Crown of Aragon, the larger part of which, with the exception of Aragon proper, are Catalan-speaking-, "Foral Spain", which includes Basque-speaking territories-, and "Colonial Spain", with the last overseas colonial territories.

The process of assimilation began with secret instructions to the corregidores of the Catalan territory: they "will take the utmost care to introduce the Castilian language, for which purpose he will give the most temperate and disguised measures so that the effect is achieved, without the care being noticed." From there, actions in the service of assimilation, discreet or aggressive, were continued, and reached to the last detail, such as, in 1799, the Royal Certificate forbidding anyone to "represent, sing and dance pieces that were not in Spanish." These nationalist policies, sometimes very aggressive, and still in force, have been, and still are, the seed of repeated territorial conflicts within the State.

The nationalization process accelerated in the 19th century, in parallel to the origin of Spanish nationalism, the social, political and ideological movement that tried to shape a Spanish national identity based on the Castilian model, in conflict with the other historical nations of the State. Politicians of the time were aware that despite the aggressive policies pursued up to that time, the uniform and monocultural "Spanish nation" did not exist, as indicated in 1835 by Antonio Alcalà Galiano, when in the Cortes del Estatuto Real he defended the effort

"To make the Spanish nation a nation that neither is nor has been until now."

In 1906, the Catalanist party Solidaritat Catalana was founded to try to mitigate the economically and culturally oppressive treatment of Spain towards the Catalans. One of the responses of Spanish nationalism came from the military state with statements such as that of the publication La Correspondencia militar: "The Catalan problem is not solved, well, by freedom, but by restriction; not by palliatives and pacts, but by iron and fire". Another came from important Spanish intellectuals, such Pio Baroja and Blasco Ibañez, calling the Catalans "Jews", considered a serious insult at that time when racism was gaining strength. Building the nation (as in France, it was the state that created the nation, and not the opposite process) is an ideal that the Spanish elites constantly reiterated, and, one hundred years later than Alcalá Galiano, for example, we can also find it in the mouth of the fascist José Pemartín, who admired the German and Italian modeling policies:

"There is an intimate and decisive dualism, both in Italian fascism and in German National Socialism. On the one hand the Hegelian doctrine of the absolutism of the state is felt. The State originates in the Nation, educates and shapes the mentality of the individual; is, in Mussolini's words, the soul of the soul »

The turn of the 20th century, and the first half of that century, have seen the most ethnic violence, coinciding with a racism that even came to identify states with races; in the case of Spain, with a supposed Spanish race sublimated in Castilian, of which national minorities were degenerate forms, and the first of those that needed to be exterminated. In this sense, one can find discourses on the alienation of Catalan speakers, such as, for example, an article entitled «Cataluña bilingüe», by Menéndez Pidal, in which he defends the Romanones decree against the Catalan language, published in El Imparcial, on 15 December 1902:

«… There they will see that the Courts of the Catalan-Aragonese Confederation never had Catalan as their official language; that the kings of Aragon, even those of the Catalan dynasty, used Catalan only in Catalonia, and used Spanish not only in the Cortes of Aragon, but also in foreign relations, the same with Castile or Navarre as with the infidel kings of Granada , from Africa or Asia, because even in the most important days of Catalonia, Spanish prevailed as the language of the Aragonese kingdom and Catalan was reserved for the peculiar affairs of the Catalan county..."

or the article "Los Catalanes. A las Cortes Constituyentes », appeared in several newspapers, among others: El Dia de Alicante, June 23, 1931, El Porvenir Castellano and El Noticiero de Soria, July 2, 1931, in the Heraldo de Almeria on June 4, 1931, sent by the "Pro-Justice Committee", with a post office box in Madrid:

"The Catalanists have recently declared that they are not Spanish, nor do they want to be, nor can they be. They have also been saying for a long time that they are an oppressed, enslaved, exploited people. It is imperative to do them justice... That they return to Phenicia or that they go wherever they want to admit them. When the Catalan tribes saw Spain and settled in the Spanish territory that is now occupied by the provinces of Barcelona, Gerona, Lérida and Tarragona, how little they imagined that the case of the captivity of the tribes of Israel in Egypt would be repeated there! !... Let us respect his most holy will. They are eternally inadaptable... Their cowardice and selfishness leaves them no room for fraternity... So, we propose to the Constituent Cortes the expulsion of the Catalanists... You are free! The Republic opens wide the doors of Spain, your prison. go away Get out of here. Go back to Phenicia, or go wherever you want, how big is the world."

The main scapegoat of Spanish nationalism is the non-Spanish languages, which over the last three hundred years have been tried to be replaced by Spanish with hundreds of laws and regulations, but also with acts of great violence, such as during the civil war. For example, the statements of Queipo de Llano can be found in the article entitled "Against Catalonia, the Israel of the Modern World", published in the Diario Palentino on November 26, 1936, where it is dropped that in America Catalans are considered a race of Jews, because they use the same procedures that the Hebrews perform in all the nations of the Globe. And considering the Catalans as Hebrews and considering his anti-Semitism "Our struggle is not a civil war, but a war for Western civilization against the Jewish world," it is not surprising that Queipo de Llano expressed his anti-Catalan intentions: "When the war is over, Pompeu Fabra and his works will be dragged along the Ramblas" (it was not talk to talk, the house of Pompeu Fabra, the standardizer of Catalan language, was raided and his huge personal library burned in the middle of the street. Pompeu Fabra was able to escape into exile). Another example of fascist aggression towards the Catalan language is pointed out by Paul Preston in "The Spanish Holocaust", given that during the civil war it practically led to an ethnic conflict:

"In the days following the occupation of Lleida (…), the republican prisoners identified as Catalans were executed without trial. Anyone who heard them speak Catalan was very likely to be arrested. The arbitrary brutality of the anti-Catalan repression reached such a point that Franco himself had to issue an order ordering that mistakes that could later be regretted be avoided ". "There are examples of the murder of peasants for no other apparent reason than that of speaking Catalan"

After a possible attempt at ethnic cleansing, the biopolitical imposition of Spanish during the Franco dictatorship, to the point of being considered an attempt at cultural genocide, democracy consolidated an asymmetric regime of bilingualism, in what has progressively been woven a web of laws and aids that privigate Spanish against Catalan, which becomes the weak language of bilingualism, and therefore, in the absence of other states where it is spoken, is doomed to extinction in the medium or short term. In the same vein, its use in the Spanish Congress is prevented, and it is prevented from being official in Europe, unlike less spoken languages such as Gaelic. In other institutional areas, such as justice, Plataforma per la Llengua has denounced Catalanophobia. The association Soberania i Justícia have also denounced it in an act in the European Parliament.

In November 2005, Omnium Cultural organized a meeting of Catalan and Madrid intellectuals in the Círculo de bellas artes in Madrid to show support for ongoing reform of Catalan Statute of Autonomy, which sought to resolve territorial tensions, and among other things better protect the Catalan language. On the Catalan side, a flight was made with one hundred representatives of the cultural, civic, intellectual, artistic and sporting world of Catalonia, but on the Spanish side, except Santiago Carrillo, a politician from the Second Republic, did not attend any more. The subsequent failure of the statutory reform with respect to its objectives opened the door to the growth of Catalan sovereignty.

Apart from language discrimination by public officials, e.g. in the hospitals, the current prohibition of using the Catalan language in state institutions such as Court, despite being the former Crown of Aragon, with three Catalan-speaking territories, one of the co-founders of the current Spanish state, is nothing more than the continuation of the foreignization of Catalan-speaking people from the first third of the 20th century, in full swing of state racism and fascism. It also can be pointed the linguistic secessionism, originally advocated by the Spanish far right and which has finally been adopted by the Spanish government itself and state bodies. By fragmenting Catalan language into as many languages as territories, it becomes inoperative, economically suffocated, and becomes a political toy in the hands of territorial politicians.

Susceptible to be classified as an ethnic democracy, the Spanish State currently only recognizes the gypsies as a national minority, excluding Catalans (and, of course, Valencians and Balearic), Basques and Galicians. However, it is evident to any external observer that there are social diversities within the Spanish State that qualify as manifestations of national minorities, such as, for example, the existence of the main three linguistic minorities in their ancestral territories.

United Kingdom

The United Kingdom is an unusual example of a nation state due to its "countries within a country". The United Kingdom is formed by the union of England, Scotland, Wales and Northern Ireland, but it is a unitary state formed initially by the merger of two independent kingdoms, the Kingdom of England (which already included Wales) and the Kingdom of Scotland, but the Treaty of Union (1707) that set out the agreed terms has ensured the continuation of distinct features of each state, including separate legal systems and separate national churches.

In 2003, the British Government described the United Kingdom as "countries within a country". While the Office for National Statistics and others describe the United Kingdom as a "nation state", others, including a then Prime Minister, describe it as a "multinational state", and the term Home Nations is used to describe the four national teams that represent the four nations of the United Kingdom (England, Northern Ireland, Scotland, Wales). Some refer to it as a "Union State".

There has been academic debate over whether the United Kingdom can be legally dissolved, as it is recognized internationally as a single nation state. English law jurist A.V. Dicey wrote from an English legal perspective that the question is based on whether the legislation giving rise to the union (the Union with Scotland Act), one of the two pieces of legislation which created the state, can be repealed. Dicey claimed because the Law of England does not acknowledge the word "unconstitutional", as a matter of English law it can be repealed. He also stated any tampering with the Acts of Union 1707 would be political madness.

Minorities

The most obvious deviation from the ideal of "one nation, one state" is the presence of minorities, especially ethnic minorities, which are clearly not members of the majority nation. An ethnic nationalist definition of a nation is necessarily exclusive: ethnic nations typically do not have open membership. In most cases, there is a clear idea that surrounding nations are different, and that includes members of those nations who live on the "wrong side" of the border. Historical examples of groups who have been specifically singled out as outsiders are the Roma and Jews in Europe.

Negative responses to minorities within the nation state have ranged from cultural assimilation enforced by the state, to expulsion, persecution, violence, and extermination. The assimilation policies are usually enforced by the state, but violence against minorities is not always state-initiated: it can occur in the form of mob violence such as lynching or pogroms. Nation states are responsible for some of the worst historical examples of violence against minorities not considered part of the nation.

However, many nation states accept specific minorities as being part of the nation, and the term national minority is often used in this sense. The Sorbs in Germany are an example: for centuries they have lived in German-speaking states, surrounded by a much larger ethnic German population, and they have no other historical territory. They are now generally considered to be part of the German nation and are accepted as such by the Federal Republic of Germany, which constitutionally guarantees their cultural rights. Of the thousands of ethnic and cultural minorities in nation states across the world, only a few have this level of acceptance and protection.

Multiculturalism is an official policy in some states, establishing the ideal of coexisting existence among multiple and separate ethnic, cultural, and linguistic groups. Other states preffer the interculturalism (or "melting pot" approach) alternative to multiculturalism, citing problems with latter as promoting self-segregation tendencies among minority groups, challenging national cohesion, polarizing society in groups that can't relate to one another, generating problems in regard to minorities and immigrants' fluency in the national language of use and integration with the rest of society (generating hate and persecution against them from the "otherness" they would generate in such a case according to its adherants), without minorities having to give up certain parts of their culture before being absorbed into a now changed majority culture by their contribution. Many nations have laws protecting minority rights.

When national boundaries that do not match ethnic boundaries are drawn, such as in the Balkans and Central Asia, ethnic tension, massacres and even genocide, sometimes has occurred historically (see Bosnian genocide and 2010 South Kyrgyzstan ethnic clashes).

Irredentism

The Greater German Reich under Nazi Germany in 1943

In principle, the border of a nation state would extend far enough to include all the members of the nation, and all of the national homeland. Again, in practice, some of them always live on the 'wrong side' of the border. Part of the national homeland may be there too, and it may be governed by the 'wrong' nation. The response to the non-inclusion of territory and population may take the form of irredentism: demands to annex unredeemed territory and incorporate it into the nation state.

Irredentist claims are usually based on the fact that an identifiable part of the national group lives across the border. However, they can include claims to territory where no members of that nation live at present, because they lived there in the past, the national language is spoken in that region, the national culture has influenced it, geographical unity with the existing territory, or a wide variety of other reasons. Past grievances are usually involved and can cause revanchism.

It is sometimes difficult to distinguish irredentism from pan-nationalism, since both claim that all members of an ethnic and cultural nation belong in one specific state. Pan-nationalism is less likely to specify the nation ethnically. For instance, variants of Pan-Germanism have different ideas about what constituted Greater Germany, including the confusing term Grossdeutschland, which, in fact, implied the inclusion of huge Slavic minorities from the Austro-Hungarian Empire.

Typically, irredentist demands are at first made by members of non-state nationalist movements. When they are adopted by a state, they typically result in tensions, and actual attempts at annexation are always considered a casus belli, a cause for war. In many cases, such claims result in long-term hostile relations between neighbouring states. Irredentist movements typically circulate maps of the claimed national territory, the greater nation state. That territory, which is often much larger than the existing state, plays a central role in their propaganda.

Irredentism should not be confused with claims to overseas colonies, which are not generally considered part of the national homeland. Some French overseas colonies would be an exception: French rule in Algeria unsuccessfully treated the colony as a département of France.

Future

It has been speculated by both proponents of globalization and various science fiction writers that the concept of a nation state may disappear with the ever-increasing interconnectedness of the world. Such ideas are sometimes expressed around concepts of a world government. Another possibility is a societal collapse and move into communal anarchy or zero world government, in which nation states no longer exist.

Clash of civilizations

The theory of the clash of civilizations lies in direct contrast to cosmopolitan theories about an ever more connected world that no longer requires nation states. According to political scientist Samuel P. Huntington, people's cultural and religious identities will be the primary source of conflict in the post–Cold War world.

The theory was originally formulated in a 1992 lecture at the American Enterprise Institute, which was then developed in a 1993 Foreign Affairs article titled "The Clash of Civilizations?", in response to Francis Fukuyama's 1992 book, The End of History and the Last Man. Huntington later expanded his thesis in a 1996 book The Clash of Civilizations and the Remaking of World Order.

Huntington began his thinking by surveying the diverse theories about the nature of global politics in the post–Cold War period. Some theorists and writers argued that human rights, liberal democracy and capitalist free market economics had become the only remaining ideological alternative for nations in the post–Cold War world. Specifically, Francis Fukuyama, in The End of History and the Last Man, argued that the world had reached a Hegelian "end of history".

Huntington believed that while the age of ideology had ended, the world had reverted only to a normal state of affairs characterized by cultural conflict. In his thesis, he argued that the primary axis of conflict in the future will be along cultural and religious lines.

As an extension, he posits that the concept of different civilizations, as the highest rank of cultural identity, will become increasingly useful in analyzing the potential for conflict.

In the 1993 Foreign Affairs article, Huntington writes:

It is my hypothesis that the fundamental source of conflict in this new world will not be primarily ideological or primarily economic. The great divisions among humankind and the dominating source of conflict will be cultural. Nation states will remain the most powerful actors in world affairs, but the principal conflicts of global politics will occur between nations and groups of different civilizations. The clash of civilizations will dominate global politics. The fault lines between civilizations will be the battle lines of the future.

Sandra Joireman suggests that Huntington may be characterised as a neo-primordialist, as, while he sees people as having strong ties to their ethnicity, he does not believe that these ties have always existed.

Historiography

Historians often look to the past to find the origins of a particular nation state. Indeed, they often put so much emphasis on the importance of the nation state in modern times, that they distort the history of earlier periods in order to emphasize the question of origins. Lansing and English argue that much of the medieval history of Europe was structured to follow the historical winners—especially the nation states that emerged around Paris and London. Important developments that did not directly lead to a nation state get neglected, they argue:

one effect of this approach has been to privilege historical winners, aspects of medieval Europe that became important in later centuries, above all the nation state.... Arguably the liveliest cultural innovation in the 13th century was the Mediterranean, centered on Frederick II's polyglot court and administration in Palermo...Sicily and the Italian South in later centuries suffered a long slide into overtaxed poverty and marginality. Textbook narratives, therefore, focus not on medieval Palermo, with its Muslim and Jewish bureaucracies and Arabic-speaking monarch, but on the historical winners, Paris and London.

Ultrasound

From Wikipedia, the free encyclopedia

Ultrasound image (sonogram) of a fetus in the womb, viewed at 12 weeks of pregnancy (bidimensional scan)
 
An ultrasonic examination
 
Fetal ultrasound

Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is approximately 20 kilohertz (20,000 hertz) in healthy young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz.

Ultrasound is used in many different fields. Ultrasonic devices are used to detect objects and measure distances. Ultrasound imaging or sonography is often used in medicine. In the nondestructive testing of products and structures, ultrasound is used to detect invisible flaws. Industrially, ultrasound is used for cleaning, mixing, and accelerating chemical processes. Animals such as bats and porpoises use ultrasound for locating prey and obstacles.

History

Galton whistle, one of the first devices to produce ultrasound

Acoustics, the science of sound, starts as far back as Pythagoras in the 6th century BC, who wrote on the mathematical properties of stringed instruments. Echolocation in bats was discovered by Lazzaro Spallanzani in 1794, when he demonstrated that bats hunted and navigated by inaudible sound, not vision. Francis Galton in 1893 invented the Galton whistle, an adjustable whistle that produced ultrasound, which he used to measure the hearing range of humans and other animals, demonstrating that many animals could hear sounds above the hearing range of humans. The first technological application of ultrasound was an attempt to detect submarines by Paul Langevin in 1917. The piezoelectric effect, discovered by Jacques and Pierre Curie in 1880, was useful in transducers to generate and detect ultrasonic waves in air and water.

Definition

Approximate frequency ranges corresponding to ultrasound, with rough guide of some applications

Ultrasound is defined by the American National Standards Institute as "sound at frequencies greater than 20 kHz". In air at atmospheric pressure, ultrasonic waves have wavelengths of 1.9 cm or less.

Perception

A medical ultrasound result on a piece of paper

Humans

The upper frequency limit in humans (approximately 20 kHz) is due to limitations of the middle ear. Auditory sensation can occur if high‐intensity ultrasound is fed directly into the human skull and reaches the cochlea through bone conduction, without passing through the middle ear.

Children can hear some high-pitched sounds that older adults cannot hear, because in humans the upper limit pitch of hearing tends to decrease with age. An American cell phone company has used this to create ring signals that supposedly are only audible to younger humans, but many older people can hear the signals, which may be because of the considerable variation of age-related deterioration in the upper hearing threshold. The Mosquito is an electronic device that uses a high pitched frequency to deter loitering by young people.

Animals

Bats use ultrasounds to navigate in the darkness.
 
A dog whistle, a whistle which emits sound in the ultrasonic range, used to train dogs and other animals

Bats use a variety of ultrasonic ranging (echolocation) techniques to detect their prey. They can detect frequencies beyond 100 kHz, possibly up to 200 kHz.

Many insects have good ultrasonic hearing, and most of these are nocturnal insects listening for echolocating bats. These include many groups of moths, beetles, praying mantises and lacewings. Upon hearing a bat, some insects will make evasive manoeuvres to escape being caught. Ultrasonic frequencies trigger a reflex action in the noctuid moth that causes it to drop slightly in its flight to evade attack. Tiger moths also emit clicks which may disturb bats' echolocation, and in other cases may advertise the fact that they are poisonous by emitting sound.

Dogs and cats' hearing range extends into the ultrasound; the top end of a dog's hearing range is about 45 kHz, while a cat's is 64 kHz. The wild ancestors of cats and dogs evolved this higher hearing range to hear high-frequency sounds made by their preferred prey, small rodents. A dog whistle is a whistle that emits ultrasound, used for training and calling dogs. The frequency of most dog whistles is within the range of 23 to 54 kHz.

Toothed whales, including dolphins, can hear ultrasound and use such sounds in their navigational system (biosonar) to orient and to capture prey. Porpoises have the highest known upper hearing limit at around 160 kHz. Several types of fish can detect ultrasound. In the order Clupeiformes, members of the subfamily Alosinae (shad) have been shown to be able to detect sounds up to 180 kHz, while the other subfamilies (e.g. herrings) can hear only up to 4 kHz.

Contrary to popular belief, birds cannot hear ultrasonic sound.

Ultrasound generator/speaker systems are sold as electronic pest control devices, which are claimed to frighten away rodents and insects, but there is no scientific evidence that the devices work.

Detection and ranging

Non-contact sensor

An ultrasonic level or sensing system requires no contact with the target. For many processes in the medical, pharmaceutical, military and general industries this is an advantage over inline sensors that may contaminate the liquids inside a vessel or tube or that may be clogged by the product.

Both continuous wave and pulsed systems are used. The principle behind a pulsed-ultrasonic technology is that the transmit signal consists of short bursts of ultrasonic energy. After each burst, the electronics looks for a return signal within a small window of time corresponding to the time it takes for the energy to pass through the vessel. Only a signal received during this window will qualify for additional signal processing.

A popular consumer application of ultrasonic ranging was the Polaroid SX-70 camera, which included a lightweight transducer system to focus the camera automatically. Polaroid later licensed this ultrasound technology and it became the basis of a variety of ultrasonic products.

Motion sensors and flow measurement

A common ultrasound application is an automatic door opener, where an ultrasonic sensor detects a person's approach and opens the door. Ultrasonic sensors are also used to detect intruders; the ultrasound can cover a wide area from a single point. The flow in pipes or open channels can be measured by ultrasonic flowmeters, which measure the average velocity of flowing liquid. In rheology, an acoustic rheometer relies on the principle of ultrasound. In fluid mechanics, fluid flow can be measured using an ultrasonic flow meter.

Nondestructive testing

Principle of flaw detection with ultrasound. A void in the solid material reflects some energy back to the transducer, which is detected and displayed.

Ultrasonic testing is a type of nondestructive testing commonly used to find flaws in materials and to measure the thickness of objects. Frequencies of 2 to 10 MHz are common, but for special purposes other frequencies are used. Inspection may be manual or automated and is an essential part of modern manufacturing processes. Most metals can be inspected as well as plastics and aerospace composites. Lower frequency ultrasound (50–500 kHz) can also be used to inspect less dense materials such as wood, concrete and cement.

Ultrasound inspection of welded joints has been an alternative to radiography for nondestructive testing since the 1960s. Ultrasonic inspection eliminates the use of ionizing radiation, with safety and cost benefits. Ultrasound can also provide additional information such as the depth of flaws in a welded joint. Ultrasonic inspection has progressed from manual methods to computerized systems that automate much of the process. An ultrasonic test of a joint can identify the existence of flaws, measure their size, and identify their location. Not all welded materials are equally amenable to ultrasonic inspection; some materials have a large grain size that produces a high level of background noise in measurements.

Non-destructive testing of a swing shaft showing spline cracking

Ultrasonic thickness measurement is one technique used to monitor quality of welds.

Ultrasonic range finding

Principle of an active sonar
 

A common use of ultrasound is in underwater range finding; this use is also called Sonar. An ultrasonic pulse is generated in a particular direction. If there is an object in the path of this pulse, part or all of the pulse will be reflected back to the transmitter as an echo and can be detected through the receiver path. By measuring the difference in time between the pulse being transmitted and the echo being received, it is possible to determine the distance.

The measured travel time of Sonar pulses in water is strongly dependent on the temperature and the salinity of the water. Ultrasonic ranging is also applied for measurement in air and for short distances. For example, hand-held ultrasonic measuring tools can rapidly measure the layout of rooms.

Although range finding underwater is performed at both sub-audible and audible frequencies for great distances (1 to several kilometers), ultrasonic range finding is used when distances are shorter and the accuracy of the distance measurement is desired to be finer. Ultrasonic measurements may be limited through barrier layers with large salinity, temperature or vortex differentials. Ranging in water varies from about hundreds to thousands of meters, but can be performed with centimeters to meters accuracy

Ultrasound Identification (USID)

Ultrasound Identification (USID) is a Real-Time Locating System (RTLS) or Indoor Positioning System (IPS) technology used to automatically track and identify the location of objects in real time using simple, inexpensive nodes (badges/tags) attached to or embedded in objects and devices, which then transmit an ultrasound signal to communicate their location to microphone sensors.

Imaging

Sonogram of a fetus at 14 weeks (profile)
 
Head of a fetus, aged 29 weeks, in a "3D ultrasound"

The potential for ultrasonic imaging of objects, with a 3 GHz sound wave producing resolution comparable to an optical image, was recognized by Sokolov in 1939, but techniques of the time produced relatively low-contrast images with poor sensitivity. Ultrasonic imaging uses frequencies of 2 megahertz and higher; the shorter wavelength allows resolution of small internal details in structures and tissues. The power density is generally less than 1 watt per square centimetre to avoid heating and cavitation effects in the object under examination. High and ultra high ultrasound waves are used in acoustic microscopy, with frequencies up to 4 gigahertz. Ultrasonic imaging applications include industrial nondestructive testing, quality control and medical uses.

Acoustic microscopy

Acoustic microscopy is the technique of using sound waves to visualize structures too small to be resolved by the human eye. Frequencies up to several gigahertz are used in acoustic microscopes. The reflection and diffraction of sound waves from microscopic structures can yield information not available with light.

Human medicine

Medical ultrasound is an ultrasound-based diagnostic medical imaging technique used to visualize muscles, tendons, and many internal organs to capture their size, structure and any pathological lesions with real time tomographic images. Ultrasound has been used by radiologists and sonographers to image the human body for at least 50 years and has become a widely used diagnostic tool. The technology is relatively inexpensive and portable, especially when compared with other techniques, such as magnetic resonance imaging (MRI) and computed tomography (CT). Ultrasound is also used to visualize fetuses during routine and emergency prenatal care. Such diagnostic applications used during pregnancy are referred to as obstetric sonography. As currently applied in the medical field, properly performed ultrasound poses no known risks to the patient. Sonography does not use ionizing radiation, and the power levels used for imaging are too low to cause adverse heating or pressure effects in tissue. Although the long-term effects due to ultrasound exposure at diagnostic intensity are still unknown, currently most doctors feel that the benefits to patients outweigh the risks. The ALARA (As Low As Reasonably Achievable) principle has been advocated for an ultrasound examination – that is, keeping the scanning time and power settings as low as possible but consistent with diagnostic imaging – and that by that principle nonmedical uses, which by definition are not necessary, are actively discouraged.

Ultrasound is also increasingly being used in trauma and first aid cases, with emergency ultrasound becoming a staple of most EMT response teams. Furthermore, ultrasound is used in remote diagnosis cases where teleconsultation is required, such as scientific experiments in space or mobile sports team diagnosis.

According to RadiologyInfo, ultrasounds are useful in the detection of pelvic abnormalities and can involve techniques known as abdominal (transabdominal) ultrasound, vaginal (transvaginal or endovaginal) ultrasound in women, and also rectal (transrectal) ultrasound in men.

Veterinary medicine

Diagnostic ultrasound is used externally in horses for evaluation of soft tissue and tendon injuries, and internally in particular for reproductive work – evaluation of the reproductive tract of the mare and pregnancy detection. It may also be used in an external manner in stallions for evaluation of testicular condition and diameter as well as internally for reproductive evaluation (deferent duct etc.).

By 2005, ultrasound technology began to be used by the beef cattle industry to improve animal health and the yield of cattle operations. Ultrasound is used to evaluate fat thickness, rib eye area, and intramuscular fat in living animals. It is also used to evaluate the health and characteristics of unborn calves.

Ultrasound technology provides a means for cattle producers to obtain information that can be used to improve the breeding and husbandry of cattle. The technology can be expensive, and it requires a substantial time commitment for continuous data collection and operator training. Nevertheless, this technology has proven useful in managing and running a cattle breeding operation.

Processing and power

High-power applications of ultrasound often use frequencies between 20 kHz and a few hundred kHz. Intensities can be very high; above 10 watts per square centimeter, cavitation can be inducted in liquid media, and some applications use up to 1000 watts per square centimeter. Such high intensities can induce chemical changes or produce significant effects by direct mechanical action, and can inactivate harmful microorganisms.

Physical therapy

Ultrasound has been used since the 1940s by physical and occupational therapists for treating connective tissue: ligaments, tendons, and fascia (and also scar tissue). Conditions for which ultrasound may be used for treatment include the follow examples: ligament sprains, muscle strains, tendonitis, joint inflammation, plantar fasciitis, metatarsalgia, facet irritation, impingement syndrome, bursitis, rheumatoid arthritis, osteoarthritis, and scar tissue adhesion.

Biomedical applications

Ultrasound has diagnostic and therapeutic applications, which can be highly beneficial when used with dosage precautions. Relatively high power ultrasound can break up stony deposits or tissue, accelerate the effect of drugs in a targeted area, assist in the measurement of the elastic properties of tissue, and can be used to sort cells or small particles for research.

Ultrasonic impact treatment

Ultrasonic impact treatment (UIT) uses ultrasound to enhance the mechanical and physical properties of metals. It is a metallurgical processing technique in which ultrasonic energy is applied to a metal object. Ultrasonic treatment can result in controlled residual compressive stress, grain refinement and grain size reduction. Low and high cycle fatigue are enhanced and have been documented to provide increases up to ten times greater than non-UIT specimens. Additionally, UIT has proven effective in addressing stress corrosion cracking, corrosion fatigue and related issues.

When the UIT tool, made up of the ultrasonic transducer, pins and other components, comes into contact with the work piece it acoustically couples with the work piece, creating harmonic resonance. This harmonic resonance is performed at a carefully calibrated frequency, to which metals respond very favorably.

Depending on the desired effects of treatment a combination of different frequencies and displacement amplitude is applied. These frequencies range between 25 and 55 kHz, with the displacement amplitude of the resonant body of between 22 and 50 µm (0.00087 and 0.0020 in).

UIT devices rely on magnetostrictive transducers.

Processing

Ultrasonication offers great potential in the processing of liquids and slurries, by improving the mixing and chemical reactions in various applications and industries. Ultrasonication generates alternating low-pressure and high-pressure waves in liquids, leading to the formation and violent collapse of small vacuum bubbles. This phenomenon is termed cavitation and causes high speed impinging liquid jets and strong hydrodynamic shear-forces. These effects are used for the deagglomeration and milling of micrometre and nanometre-size materials as well as for the disintegration of cells or the mixing of reactants. In this aspect, ultrasonication is an alternative to high-speed mixers and agitator bead mills. Ultrasonic foils under the moving wire in a paper machine will use the shock waves from the imploding bubbles to distribute the cellulose fibres more uniformly in the produced paper web, which will make a stronger paper with more even surfaces. Furthermore, chemical reactions benefit from the free radicals created by the cavitation as well as from the energy input and the material transfer through boundary layers. For many processes, this sonochemical (see sonochemistry) effect leads to a substantial reduction in the reaction time, like in the transesterification of oil into biodiesel.

Schematic of bench and industrial-scale ultrasonic liquid processors

Substantial ultrasonic intensity and high ultrasonic vibration amplitudes are required for many processing applications, such as nano-crystallization, nano-emulsification, deagglomeration, extraction, cell disruption, as well as many others. Commonly, a process is first tested on a laboratory scale to prove feasibility and establish some of the required ultrasonic exposure parameters. After this phase is complete, the process is transferred to a pilot (bench) scale for flow-through pre-production optimization and then to an industrial scale for continuous production. During these scale-up steps, it is essential to make sure that all local exposure conditions (ultrasonic amplitude, cavitation intensity, time spent in the active cavitation zone, etc.) stay the same. If this condition is met, the quality of the final product remains at the optimized level, while the productivity is increased by a predictable "scale-up factor". The productivity increase results from the fact that laboratory, bench and industrial-scale ultrasonic processor systems incorporate progressively larger ultrasonic horns, able to generate progressively larger high-intensity cavitation zones and, therefore, to process more material per unit of time. This is called "direct scalability". It is important to point out that increasing the power of the ultrasonic processor alone does not result in direct scalability, since it may be (and frequently is) accompanied by a reduction in the ultrasonic amplitude and cavitation intensity. During direct scale-up, all processing conditions must be maintained, while the power rating of the equipment is increased in order to enable the operation of a larger ultrasonic horn.

Ultrasonic manipulation and characterization of particles

A researcher at the Industrial Materials Research Institute, Alessandro Malutta, devised an experiment that demonstrated the trapping action of ultrasonic standing waves on wood pulp fibers diluted in water and their parallel orienting into the equidistant pressure planes. The time to orient the fibers in equidistant planes is measured with a laser and an electro-optical sensor. This could provide the paper industry a quick on-line fiber size measurement system. A somewhat different implementation was demonstrated at Pennsylvania State University using a microchip which generated a pair of perpendicular standing surface acoustic waves allowing to position particles equidistant to each other on a grid. This experiment, called acoustic tweezers, can be used for applications in material sciences, biology, physics, chemistry and nanotechnology.

Ultrasonic cleaning

Ultrasonic cleaners, sometimes mistakenly called supersonic cleaners, are used at frequencies from 20 to 40 kHz for jewellery, lenses and other optical parts, watches, dental instruments, surgical instruments, diving regulators and industrial parts. An ultrasonic cleaner works mostly by energy released from the collapse of millions of microscopic cavitations near the dirty surface. The bubbles made by cavitation collapse form tiny shockwaves that break up and disperse contaminants on the object's surface.

Ultrasonic disintegration

Similar to ultrasonic cleaning, biological cells including bacteria can be disintegrated. High power ultrasound produces cavitation that facilitates particle disintegration or reactions. This has uses in biological science for analytical or chemical purposes (sonication and sonoporation) and in killing bacteria in sewage. High power ultrasound can disintegrate corn slurry and enhance liquefaction and saccharification for higher ethanol yield in dry corn milling plants.

Ultrasonic humidifier

The ultrasonic humidifier, one type of nebulizer (a device that creates a very fine spray), is a popular type of humidifier. It works by vibrating a metal plate at ultrasonic frequencies to nebulize (sometimes incorrectly called "atomize") the water. Because the water is not heated for evaporation, it produces a cool mist. The ultrasonic pressure waves nebulize not only the water but also materials in the water including calcium, other minerals, viruses, fungi, bacteria, and other impurities. Illness caused by impurities that reside in a humidifier's reservoir fall under the heading of "Humidifier Fever".

Ultrasonic humidifiers are frequently used in aeroponics, where they are generally referred to as foggers.

Ultrasonic welding

In ultrasonic welding of plastics, high frequency (15 kHz to 40 kHz) low amplitude vibration is used to create heat by way of friction between the materials to be joined. The interface of the two parts is specially designed to concentrate the energy for maximum weld strength.

Sonochemistry

Power ultrasound in the 20–100 kHz range is used in chemistry. The ultrasound does not interact directly with molecules to induce the chemical change, as its typical wavelength (in the millimeter range) is too long compared to the molecules. Instead, the energy causes cavitation which generates extremes of temperature and pressure in the liquid where the reaction happens. Ultrasound also breaks up solids and removes passivating layers of inert material to give a larger surface area for the reaction to occur over. Both of these effects make the reaction faster. In 2008, Atul Kumar reported synthesis of Hantzsch esters and polyhydroquinoline derivatives via multi-component reaction protocol in aqueous micelles using ultrasound.

Ultrasound is used in extraction, using different frequencies.

Wireless communication

In July 2015, The Economist reported that researchers at the University of California, Berkeley have conducted ultrasound studies using graphene diaphragms. The thinness and low weight of graphene combined with its strength make it an effective material to use in ultrasound communications. One suggested application of the technology would be underwater communications, where radio waves typically do not travel well.

Ultrasonic signals have been used in "audio beacons" for cross-device tracking of Internet users.

Other uses

Ultrasound when applied in specific configurations can produce short bursts of light in an exotic phenomenon known as sonoluminescence. This phenomenon is being investigated partly because of the possibility of bubble fusion (a nuclear fusion reaction hypothesized to occur during sonoluminescence).

Ultrasound is used when characterizing particulates through the technique of ultrasound attenuation spectroscopy or by observing electroacoustic phenomena or by transcranial pulsed ultrasound.

Audio can be propagated by modulated ultrasound.

A formerly popular consumer application of ultrasound was in television remote controls for adjusting volume and changing channels. Introduced by Zenith in the late 1950s, the system used a hand-held remote control containing short rod resonators struck by small hammers, and a microphone on the set. Filters and detectors discriminated between the various operations. The principal advantages were that no battery was needed in the hand-held control box and, unlike radio waves, the ultrasound was unlikely to affect neighboring sets. Ultrasound remained in use until displaced by infrared systems starting in the late 1980s.

Safety

Occupational exposure to ultrasound in excess of 120 dB may lead to hearing loss. Exposure in excess of 155 dB may produce heating effects that are harmful to the human body, and it has been calculated that exposures above 180 dB may lead to death. The UK's independent Advisory Group on Non-ionising Radiation (AGNIR) produced a report in 2010, which was published by the UK Health Protection Agency (HPA). This report recommended an exposure limit for the general public to airborne ultrasound sound pressure levels (SPL) of 70 dB (at 20 kHz), and 100 dB (at 25 kHz and above).

Representation of a Lie group

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