A Reuleaux triangle is a shape formed from the intersection of three circular disks, each having its center on the boundary of the other two. Its boundary is a curve of constant width, the simplest and best known such curve other than the circle itself. Constant width means that the separation of every two parallel supporting lines is the same, independent of their orientation; because all its diameters are the same, the Reuleaux triangle is one answer to the question "Other than a circle, what shape can a manhole cover be made so that it cannot fall down through the hole?"Reuleaux triangles have been called spherical triangles, but that term more properly refers to triangles on the curved surface of a sphere. They are named after Franz Reuleaux, a 19th-century German engineer who pioneered the study of machines for translating one type of motion into another, who used Reuleaux triangles in his designs. However, these shapes were known before his time, for instance by the designers of Gothic church windows, by Leonardo da Vinci, who used it for a map projection, by Leonhard Euler in his study of constant-width shapes.
Other applications of the Reuleaux triangle include giving the shape to guitar picks and drill bits for drilling square holes, as well as in graphic design in the shapes of some signs and corporate logos. Among constant-width shapes with a given width, the Reuleaux triangle has the minimum area and the sharpest possible angle at its corners. By several numerical measures it is the farthest from being centrally symmetric, it provides the largest constant-width shape avoiding the points of an integer lattice, is related to the shape of the quadrilateral maximizing the ratio of perimeter to diameter. It can perform a complete rotation within a square while at all times touching all four sides of the square, has the smallest possible area of shapes with this property. However, although it covers most of the square in this rotation process, it fails to cover a small fraction of the square's area, near its corners; because of this property of rotating within a square, the Reuleaux triangle is sometimes known as the Reuleaux rotor.
The Reuleaux triangle is the first of a sequence of Reuleaux polygons, whose boundaries are curves of constant width formed from regular polygons with an odd number of sides. Some of these curves have been used as the shapes of coins; the Reuleaux triangle can be generalized into three dimensions in multiple ways: the Reuleaux tetrahedron does not have constant width, but can be modified by rounding its edges to form the Meissner tetrahedron, which does. Alternatively, the surface of revolution of the Reuleaux triangle has constant width; the Reuleaux triangle may be constructed either directly from three circles, or by rounding the sides of an equilateral triangle. The three-circle construction may be performed with a compass alone, not needing a straightedge. By the Mohr–Mascheroni theorem the same is true more of any compass-and-straightedge construction, but the construction for the Reuleaux triangle is simple; the first step is to mark two arbitrary points of the plane, use the compass to draw a circle centered at one of the marked points, through the other marked point.
Next, one draws a second circle, of the same radius, centered at the other marked point and passing through the first marked point. One draws a third circle, again of the same radius, with its center at one of the two crossing points of the two previous circles, passing through both marked points; the central region in the resulting arrangement of three circles will be a Reuleaux triangle. Alternatively, a Reuleaux triangle may be constructed from an equilateral triangle T by drawing three arcs of circles, each centered at one vertex of T and connecting the other two vertices. Or, equivalently, it may be constructed as the intersection of three disks centered at the vertices of T, with radius equal to the side length of T; the most basic property of the Reuleaux triangle is that it has constant width, meaning that for every pair of parallel supporting lines the two lines have the same Euclidean distance from each other, regardless of the orientation of these lines. In any pair of parallel supporting lines, one of the two lines will touch the triangle at one of its vertices.
The other supporting line may touch the triangle at any point on the opposite arc, their distance equals the radius of this arc. The first mathematician to discover the existence of curves of constant width, to observe that the Reuleaux triangle has constant width, may have been Leonhard Euler. In a paper that he presented in 1771 and published in 1781 entitled De curvis triangularibus, Euler studied curvilinear triangles as well as the curves of constant width, which he called orbiforms. By many different measures, the Reuleaux triangle is one of the most extreme curves of constant width. By the Blaschke–Lebesgue theorem, the Reuleaux triangle has the smallest possible area of any curve of given constant width; this area is 1 2. One method for deriving this area formula is to partition the Reuleaux triangle into an inner equilateral triangle and three curvilinear regions between this inner triangle and the arcs forming the Reuleaux triangle, add the
The lion is a species in the family Felidae. The lion is sexually dimorphic. Male lions have a prominent mane, the most recognisable feature of the species. A lion pride consists of related females and cubs. Groups of female lions hunt together, preying on large ungulates; the species is an keystone predator, although they scavenge when opportunities occur. Some lions have been known to hunt humans, although the species does not; the lion inhabits grasslands and savannas but is absent in dense forests. It is more diurnal than other big cats, but when persecuted it adapts to being active at night and at twilight. In the Pleistocene, the lion ranged throughout Eurasia and North America but today it has been reduced to fragmented populations in Sub-Saharan Africa and one critically endangered population in western India, it has been listed as Vulnerable on the IUCN Red List since 1996 because populations in African countries have declined by about 43% since the early 1990s. Lion populations are untenable outside designated protected areas.
Although the cause of the decline is not understood, habitat loss and conflicts with humans are the greatest causes for concern. One of the most recognised animal symbols in human culture, the lion has been extensively depicted in sculptures and paintings, on national flags, in contemporary films and literature. Lions have been kept in menageries since the time of the Roman Empire and have been a key species sought for exhibition in zoological gardens across the world since the late 18th century. Cultural depictions of lions were prominent in the Upper Paleolithic period; the lion's name, similar in many Romance languages, is derived from Latin: leo and Ancient Greek: λέων. The word lavi may be related. Felis leo was the scientific name used by Carl Linnaeus in 1758, who described the lion in his work Systema Naturae; the genus name Panthera was coined by German naturalist Lorenz Oken in 1816. Between the mid-18th and mid-20th centuries, 26 lion specimens were described and proposed as subspecies, of which 11 were recognised as valid in 2005.
They were distinguished on the basis of appearance and colour of mane. Because these characteristics show much variation between individuals, most of these forms were not true subspecies because they were based upon museum material with "striking, but abnormal" morphological characteristics. Based on the morphology of 58 lion skulls in three European museums, the subspecies krugeri, nubica and senegalensis were assessed distinct but bleyenberghi overlapped with senegalensis and krugeri; the Asiatic lion persica was the most distinctive and the Cape lion had characteristics allying it more with persica than the other sub-Saharan lions. The lion's closest relatives are the other species of the genus Panthera. Results of phylogenetic studies published in 2006 and 2009 indicate that the jaguar and the lion belong to one sister group that diverged about 2.06 million years ago. Results of studies published in 2010 and 2011 indicate that the leopard and the lion belong to the same sister group, which diverged between 1.95 and 3.10 million years ago.
Hybridisation between lion and snow leopard ancestors, may have continued until about 2.1 million years ago. In the 19th and 20th centuries, several lion type specimens were described and proposed as subspecies, with about a dozen recognised as valid taxa until 2017. Between 2008 and 2016, IUCN Red List assessors used only two subspecific names: P. l. leo for African lion populations and P. l. persica for the Asiatic lion population. In 2017, the Cat Classification Task Force of the Cat Specialist Group revised lion taxonomy, recognises two subspecies based on results of several phylogeographic studies on lion evolution, namely: P. l. leo − the nominate lion subspecies includes the Asiatic lion, the regionally extinct Barbary lion, lion populations in West and northern parts of Central Africa. Synonyms include P. l. persica, P. l. senegalensis, P. l. kamptzi, P. l. azandica. Some authors referred to it as'Northern lion' and'northern subspecies'. P. l. melanochaita − includes the extinct Cape lion and lion populations in East and Southern African regions.
Synonyms include P. l. somaliensis, P. l. massaica, P. l. sabakiensis, P. l. bleyenberghi, P. l. roosevelti, P. l. nyanzae, P. l. hollisteri, P. l. krugeri, P. l. vernayi, P. l. webbiensis. It has been referred to as'southern subspecies'. Early phylogenetic research was focused on East and Southern African lions, showed they can be divided in two main clades. Lions in eastern Kenya are genetically much closer to lions in Southern Africa than to lions in Aberdare National Park in western Kenya. In a subsequent study and bone samples of 32 lion specimens in museums were used. Results indicated lions form
National Health Service
The NHS in England, NHS Scotland, NHS Wales, the affiliated Health and Social Care in Northern Ireland were established together in 1948 as one of the major social reforms following the Second World War. The founding principles were that services should be comprehensive and free at the point of delivery; each service provides a comprehensive range of health services, free at the point of use for people ordinarily resident in the United Kingdom, apart from dental treatment and optical care. Dr Somerville Hastings, President of the Socialist Medical Association proposed a resolution at the 1934 Labour Party Conference that the party should be committed to the establishment of a State Health Service. Conservative MP and Health Minister, Henry Willink, first proposed the National Health Service in 1944 with the publication of a White Paper "A National Health Service", distributed in full and short versions as well as in newsreel by Henry Willink himself. Henry Willink's National Health Service received cross party support and became Westminster legislation for England and Wales from 1946 and Scotland from 1947, the Northern Ireland Parliament's Public Health Services Act 1947.
NHS Wales was split from NHS in 1969 when control was passed to the Secretary of State for Wales before transferring to the Welsh Executive and Assembly under devolution in 1999. Calls for a "unified medical service" can be dated back to the Minority Report of the Royal Commission on the Poor Law in 1909, but it was following the 1942 Beveridge Report's recommendation to create "comprehensive health and rehabilitation services for prevention and cure of disease" that cross-party consensus emerged on introducing a National Health Service of some description; when Clement Attlee's Labour Party won the 1945 election he appointed Aneurin Bevan as Health Minister. Bevan embarked upon what the official historian of the NHS, Charles Webster, called an "audacious campaign" to take charge of the form the NHS took; the NHS was born out of the ideal that good healthcare should be available to all, regardless of wealth. Although being accessible regardless of wealth maintained Henry Willink's principle of free healthcare for all, Conservative MPs were in favour of maintaining local administration of the NHS through existing arrangements with local authorities fearing that an NHS which owned hospitals on a national scale would lose the personal relationship between doctor and patient.
Conservative MPs voted in favour of their amendment to Bevan's Bill to maintain local control and ownership of hospitals and against Bevan's plan for national ownership of all hospitals. The Labour government defeated Conservative amendments and went ahead with the NHS as it remains today. Bevan's principle of ownership with no private sector involvement has since been diluted, with Labour governments implementing large scale financing arrangements with private builders in private finance initiatives and joint ventures. At its launch by Bevan on 5 July 1948 it had at its heart three core principles: That it meet the needs of everyone, that it be free at the point of delivery, that it be based on clinical need, not ability to pay. Three years after the founding of the NHS, Bevan resigned from the Labour government in opposition to the introduction of charges for the provision of dentures and glasses; the following year, Winston Churchill's Conservative government introduced prescription charges.
These charges were the first of many controversies over reforms to the NHS throughout its history. From its earliest days, the cultural history of the NHS has shown its place in British society reflected and debated in film, TV, cartoons and literature; the NHS had a prominent slot during the 2012 London Summer Olympics opening ceremony directed by Danny Boyle, being described as "the institution which more than any other unites our nation". Each of the UK's health service systems operates independently, is politically accountable to the relevant government: the Scottish Government. NHS Wales was part of the same structure as that of England until powers over the NHS in Wales were firstly transferred to the Secretary of State for Wales in 1969 and thereafter, in 1999, to the Welsh Assembly as part of Welsh devolution; some functions may be performed by one health service on behalf of another. For example, Northern Ireland has no high-security psychiatric hospitals and depends on hospitals in Great Britain at Carstairs hospital in Scotland for male patients and Rampton Secure Hospital in England for female patients.
Patients in North Wales use specialist facilities in Manchester and Liverpool which are much closer than facilities in Cardiff, more routine services at the Countess of Chester Hospital. There have been issues about cross-border payments. Taken together, the four National Health Services in 2015–16 employed around 1.6 million people with a combined budget of £136.7 billion. In 2014 the total health sector workforce across the UK was 2,165,043; this broke down into 1,789,586 in England, 198,368 in Scotland, 110,292 in Wales and 66,797 in Northern Ireland. In 2017, there were 691,000 nurses registered in the UK, down 1,783 from the previous year. However, this is the first time nursing numbers have fallen since 2008. Although there has been increasing policy divergence between the four National Health Services in the UK, it can b
European Single Market
The European Single Market, Internal Market or Common Market is a single market which seeks to guarantee the free movement of goods, capital and labour – the "four freedoms" – within the European Union. The market encompasses the EU's 28 member states, has been extended, with exceptions, to Iceland and Norway through the Agreement on the European Economic Area and to Switzerland through bilateral treaties. A number of potential EU accession candidates have Stabilisation and Association Agreements with the EU, which allow for limited participation in selected sectors of the Single Market, including Albania and Herzegovina, North Macedonia and Serbia. In addition, through three individual agreements on a Deep and Comprehensive Free Trade Area with the EU, the post-Soviet countries of Georgia and Ukraine have been granted limited access to the Single Market in selected sectors. Turkey has access to the free movement of some goods via its membership in the European Union–Turkey Customs Union; the market is intended to be conducive to increased competition, increased specialisation, larger economies of scale, allowing goods and factors of production to move to the area where they are most valued, thus improving the efficiency of the allocation of resources.
It is intended to drive economic integration whereby the once separate economies of the member states become integrated within a single EU-wide economy. Half the trade in goods within the EU is covered by legislation harmonised by the EU; the creation of the internal market as a seamless, single market is an ongoing process, with the integration of the service industry still containing gaps. It has an increasing international element, with the market represented as one in international trade negotiations. One of the original core objectives of the European Economic Community was the development of a common market offering free movement of goods, service and capital. Free movement of goods was established in principle through the customs union between its then-six member states; however the EEC struggled to enforce a single market due to the absence of strong decision-making structures. It was difficult to remove intangible barriers with mutual recognition of standards and common regulations due to protectionist attitudes.
In the 1980s, when the economy of the EEC began to lag behind the rest of the developed world, Margaret Thatcher sent Arthur Cockfield, Baron Cockfield, to the Delors Commission to take the initiative to attempt to relaunch the common market. Cockfield wrote and published a White Paper in 1985 identifying 300 measures to be addressed in order to complete a single market; the White Paper was well received and led to the adoption of the Single European Act, a treaty which reformed the decision-making mechanisms of the EEC and set a deadline of 31 December 1992 for the completion of a single market. In the end, it was launched on 1 January 1993; the new approach, pioneered at the Delors Commission, combined positive and negative integration, relying upon minimum rather than exhaustive harmonisation. Negative integration consists of prohibitions imposed on member states banning discriminatory behaviour and other restrictive practices. Positive integration consists of approximating standards. Important in this respect is the adoption of harmonising legislation under Article 114 of the Treaty on the Functioning of the European Union.
The Commission relied upon the European Court of Justice's Cassis de Dijon jurisprudence, under which member states were obliged to recognise goods, produced in another member state, unless the member state could justify the restriction by reference to a mandatory requirement. Harmonisation would only be used to overcome barriers created by trade restrictions which survived the Cassis mandatory requirements test, to ensure essential standards where there was a risk of a race to the bottom, thus harmonisation was used to ensure basic health and safety standards were met. By 1992 about 90% of the issues had been resolved and in the same year the Maastricht Treaty set about to create an Economic and Monetary Union as the next stage of integration. Work on freedom for services did take longer, was the last freedom to be implemented through the Posting of Workers Directive and the Directive on services in the internal market. In 1997 the Amsterdam Treaty abolished physical barriers across the internal market by incorporating the Schengen Area within the competences of the EU.
The Schengen Agreement implements the abolition of border controls between most member states, common rules on visas, police and judicial co-operation. As the Lisbon Treaty came into force in 2009 however, some areas pertaining parts of the four freedoms had not yet been opened. Those, along with further work on the economic and monetary union, would see the EU move further to a European Home Market; the European Union is a customs union. This means that member states have removed customs barriers between themselves and introduced a common customs policy towards other countries; the overall purpose of the duties is "to ensure normal conditions of competition and to remove all restrictions of a fiscal nature capable of hindering the free movement of goods within the Common Market". By agreement between the Union and the states concerned, Monaco, San Marino and Turkey participate in the EU Customs Union. Article 30 TFEU prohibits member states from levying any duties on goods crossing its border with a fellow member state and covers both goods produced within the EUCU and those produced outside.
Once a good has
A coin is a small, round piece of metal or plastic used as a medium of exchange or legal tender. They are standardized in weight, produced in large quantities at a mint in order to facilitate trade, they are most issued by a government. Coins are metal or alloy, or sometimes made of synthetic materials, they are disc shaped. Coins made of valuable metal are stored in large quantities as bullion coins. Other coins are used as money in everyday transactions; the highest value coin in circulation is worth less than the lowest-value note. In the last hundred years, the face value of circulation coins has been lower than the value of the metal they contain, for example due to inflation. If the difference becomes significant, the issuing authority may decide to withdraw these coins from circulation issuing new equivalents with a different composition, or the public may decide to melt the coins down or hoard them. Exceptions to the rule of face value being higher than content value occur for some bullion coins made of copper, silver, or gold, intended for collectors or investors in precious metals.
Examples of modern gold collector/investor coins include the British sovereign minted by the United Kingdom, the American Gold Eagle minted by the United States, the Canadian Gold Maple Leaf minted by Canada, the Krugerrand, minted by South Africa. While the Eagle, Maple Leaf, Sovereign coins have nominal face values, the Krugerrand does not. A great quantity of coinage metals and other materials have been used to produce coins for circulation and metal investment: bullion coins serve as more convenient stores of assured metal quantity and purity than other bullion. Metal ingots, silver bullion or unmarked bars were in use for exchange among many of the civilizations that mastered metallurgy; the weight and purity of bullion would be the key determinant of value. In the Achaemenid Empire in the early 6th century BC, coinage was yet unknown, barter and to some extent silver bullion was used instead for trade; the practice of using silver bars for currency seems to have been current in Central Asia from the 6th century BC.
Coins were an evolution of "currency" systems of the Late Bronze Age, where standard-sized ingots, tokens such as knife money, were used to store and transfer value. In the late Chinese Bronze Age, standardized cast tokens were made, such as those discovered in a tomb near Anyang; these were replicas in bronze of earlier Chinese currency, cowrie shells, so they were named Bronze Shell. The earliest coins are associated with Iron Age Anatolia of the late 7th century BC, with the kingdom of Lydia. Early electrum coins were not standardized in weight, in their earliest stage may have been ritual objects, such as badges or medals, issued by priests; the unpredictability of the composition of occurring electrum implied that it had a variable value, which hampered its development. Most of the early Lydian coins include no writing, only an image of a symbolic animal. Therefore, the dating of these coins relies on archaeological evidence, with the most cited evidence coming from excavations at the Temple of Artemis at Ephesus called the Ephesian Artemision, site of the earliest known deposit of electrum coins.
Because the oldest lion head "coins" were discovered in that temple, they do not appear to have been used in commerce, these objects may not have been coins but badges or medals issued by the priests of that temple. Anatolian Artemis was the Πὀτνια Θηρῶν, it took some time before ancient coins were used for trade. The smallest-denomination electrum coins worth about a day's subsistence, would have been too valuable for buying a loaf of bread; the first coins to be used for retailing on a large-scale basis were small silver fractions, Ancient Greek coinage minted by the Ionian Greeks in the late sixth century BC. Many early Lydian and Greek coins were minted under the authority of private individuals and are thus more akin to tokens or badges than to modern coins, though due to their numbers it is evident that some were official state issues; the earliest inscribed coins are those of Phanes, dated to 625–600 BC from Ephesus in Ionia, with the legend ΦΑΝΕΟΣ ΕΜΙ ΣΗΜΑ, or just bearing the name ΦΑΝΕΟΣ.
The first electrum coins issued by a monarch are those minted by king Alyattes of Lydia, for which reason this king is sometimes mentioned as the originator of coinage. The successor of Alyattes, king Croesus, became associated with great wealth in Greek historiography, he is credited with issuing the Croeseid, the first true gold coins with a standardised purity for general circulation. And the world's first bimetallic monetary system circa 550 BCE. Herodotus mentioned the innovation made by the Lydians: "So far as we have any knowledge, they were the first people to introduce the use of gold and silver coins, the first who sold goods by retail" Coins spread in the 6th and 5th centuries BC, leading to the development of Ancient Greek coinage and Achaemenid coinage, further to Illyrian coinage. Standardized Roman currency
Debt is when something money, is owed by one party, the borrower or debtor, to a second party, the lender or creditor. Debt is a deferred payment, or series of payments, owed in the future, what differentiates it from an immediate purchase; the debt may be owed by local government, company, or an individual. Commercial debt is subject to contractual terms regarding the amount and timing of repayments of principal and interest. Loans, bonds and mortgages are all types of debt; the term can be used metaphorically to cover moral obligations and other interactions not based on economic value. For example, in Western cultures, a person, helped by a second person is sometimes said to owe a "debt of gratitude" to the second person; the English term "debt" was first used in the late 13th century. The term "debt" comes from "dette, from Old French dete, from Latin debitum "thing owed," neuter past participle of debere "to owe," "keep something away from someone," from de- "away" + habere "to have". Restored spelling after c.
1400. The related term "debtor" was first used in English in the early 13th century; the -b- was restored in French, in English c. 1560-c. 1660." In the King James Bible, various spellings are used. Interest is the fee paid by the borrower to the lender. Interest is calculated as a percentage of the outstanding principal, which percentage is known as an interest rate, is paid periodically at intervals, such as monthly or semi-annually. Interest rates may be floating. In floating-rate structures, the rate of interest that the borrower pays during each time period is tied to a benchmark such as LIBOR or, in the case of inflation-indexed bonds, inflation. There are many different conventions for calculating interest. Depending on the terms of the debt, compound interest may accumulate at a specific interval. In addition, different day count conventions exist, for example, sometimes each month is considered to have thirty days, such that the interest payment due is the same in each calendar month; the annual percentage rate is a standardized way to calculate and compare interest rates on an annual basis.
Quoting interest rates using APR is required by regulation for most loans to individuals in the United States and United Kingdom. For some loans, the amount loaned to the debtor is less than the principal sum to be repaid; this may be because upfront fees or points are charged, or because the loan has been structured to be sharia-compliant. The additional principal due at the end of the term has the same economic effect as a higher interest rate. Riskier borrowers must pay higher rates of interest to compensate lenders for taking on the additional risk of default. Debt investors assess the risk of default prior to making a loan, for example through credit scores and corporate and sovereign ratings. There are three main ways repayment may be structured: the entire principal balance may be due at the maturity of the loan. Amortization structures are common in mortgages and credit cards. Debtors of every type default on their debt from time to time, with various consequences depending on the terms of the debt and the law governing default in the relevant jurisdiction.
If the debt was secured by specific collateral, such as a car or home, the creditor may seek to repossess the collateral. In more serious circumstances and companies may go into bankruptcy. Common types of debt owed by individuals and households include mortgage loans, car loans, credit card debt, income taxes. For individuals, debt is a means of using anticipated income and future purchasing power in the present before it has been earned. People in industrialized nations use consumer debt to purchase houses and other things too expensive to buy with cash on hand. People are more to spend more and get into debt when they use credit cards vs. cash for buying products and services. This is because of the transparency effect and consumer's "pain of paying." The transparency effect refers to the fact that the further you are from cash, the less transparent it is and the less you remember how much you spent. The less transparent or further away from cash, the form of payment employed is, the less an individual feels the “pain of paying” and thus is to spend more.
Furthermore, the differing physical appearance/form that credit cards have from cash may cause them to be viewed as “monopoly” money vs. real money, luring individuals to spend more money than they would if they only had cash available. Besides these more formal debts, private individuals lend informally to other people relatives or friends. One reason for such informal debts is that many people, in particular those who are poor, have no access to affordable credit; such debts can cause problems when they are not paid back according to expectations of the lending household. In 2011, 8 percent of people in the European Union reported their households has been in arrears, that is, unable to pay as scheduled "payments related to informal loans from friends or relatives not living in your household". A company may use various kinds of debt to finance its operations as a part of its overall corporate finance strate
The European Union is a political and economic union of 28 member states that are located in Europe. It has an area of an estimated population of about 513 million; the EU has developed an internal single market through a standardised system of laws that apply in all member states in those matters, only those matters, where members have agreed to act as one. EU policies aim to ensure the free movement of people, goods and capital within the internal market, enact legislation in justice and home affairs and maintain common policies on trade, agriculture and regional development. For travel within the Schengen Area, passport controls have been abolished. A monetary union was established in 1999 and came into full force in 2002 and is composed of 19 EU member states which use the euro currency; the EU and European citizenship were established when the Maastricht Treaty came into force in 1993. The EU traces its origins to the European Coal and Steel Community and the European Economic Community, established by the 1951 Treaty of Paris and 1957 Treaty of Rome.
The original members of what came to be known as the European Communities were the Inner Six: Belgium, Italy, the Netherlands, West Germany. The Communities and its successors have grown in size by the accession of new member states and in power by the addition of policy areas to its remit; the latest major amendment to the constitutional basis of the EU, the Treaty of Lisbon, came into force in 2009. While no member state has left the EU or its antecedent organisations, the United Kingdom signified the intention to leave after a membership referendum in June 2016 and is negotiating its withdrawal. Covering 7.3% of the world population, the EU in 2017 generated a nominal gross domestic product of 19.670 trillion US dollars, constituting 24.6% of global nominal GDP. Additionally, all 28 EU countries have a high Human Development Index, according to the United Nations Development Programme. In 2012, the EU was awarded the Nobel Peace Prize. Through the Common Foreign and Security Policy, the EU has developed a role in external relations and defence.
The union maintains permanent diplomatic missions throughout the world and represents itself at the United Nations, the World Trade Organization, the G7 and the G20. Because of its global influence, the European Union has been described as an emerging superpower. During the centuries following the fall of Rome in 476, several European States viewed themselves as translatio imperii of the defunct Roman Empire: the Frankish Empire and the Holy Roman Empire were thereby attempts to resurrect Rome in the West; this political philosophy of a supra-national rule over the continent, similar to the example of the ancient Roman Empire, resulted in the early Middle Ages in the concept of a renovatio imperii, either in the forms of the Reichsidee or the religiously inspired Imperium Christianum. Medieval Christendom and the political power of the Papacy are cited as conducive to European integration and unity. In the oriental parts of the continent, the Russian Tsardom, the Empire, declared Moscow to be Third Rome and inheritor of the Eastern tradition after the fall of Constantinople in 1453.
The gap between Greek East and Latin West had been widened by the political scission of the Roman Empire in the 4th century and the Great Schism of 1054. Pan-European political thought emerged during the 19th century, inspired by the liberal ideas of the French and American Revolutions after the demise of Napoléon's Empire. In the decades following the outcomes of the Congress of Vienna, ideals of European unity flourished across the continent in the writings of Wojciech Jastrzębowski, Giuseppe Mazzini or Theodore de Korwin Szymanowski; the term United States of Europe was used at that time by Victor Hugo during a speech at the International Peace Congress held in Paris in 1849: A day will come when all nations on our continent will form a European brotherhood... A day will come when we shall see... the United States of America and the United States of Europe face to face, reaching out for each other across the seas. During the interwar period, the consciousness that national markets in Europe were interdependent though confrontational, along with the observation of a larger and growing US market on the other side of the ocean, nourished the urge for the economic integration of the continent.
In 1920, advocating the creation of a European economic union, British economist John Maynard Keynes wrote that "a Free Trade Union should be established... to impose no protectionist tariffs whatever against the produce of other members of the Union." During the same decade, Richard von Coudenhove-Kalergi, one of the first to imagine of a modern political union of Europe, founded the Pan-Europa Movement. His ideas influenced his contemporaries, among which Prime Minister of France Aristide Briand. In 1929, the latter gave a speech in favour of a European Union before the assembly of the League of Nations, precursor of the United Nations. In a radio address in March 1943, with war still raging, Britain's leader Sir Winston Churchill spoke warmly of "restoring the true greatness of Europe" once victory had been achieved, mused on the post-war creation of a "Council of Europe" which would bring the European nations together to build peace. After World War II, European integration was seen as an antidote to the extreme nationalism which had devastated the continent.
In a speech delivered on 19