title: Hugh Gaitskell

text: Gaitskell took on Frank Cousins and wanted to show that Labour were a party of government, not just of opposition. At the October 1960 Scarborough Conference two resolutions in favour of unilateral disarmament – proposed by the TGWU and the Engineers’ Union – were carried, whilst the official policy document on defence was rejected. Gaitskell roused his supporters by promising to "Fight and Fight and Fight Again" to reverse the decision. Labour doctrine was that the Parliamentary Party had discretion over the timing of implementation of conference policy. In practice, in the 1940s and '50s, the unions, whose block votes dominated conference, had been broadly supportive of the PLP, but this was now beginning to change. Gaitskell was challenged unsuccessfully for the leadership by Harold Wilson in November 1960.


title: Hugh Gaitskell

text: The Blackpool Conference of October 1961 saw a narrow conference vote in favour of "multi"lateral disarmament. Winning the unilateralism vote in 1961 restored Gaitskell's authority in the party and his reputation in the country. Unilateral nuclear disarmament remained a divisive issue, and many on the Left continued to call for a change of leadership. Gaitskell was again challenged unsuccessfully for the Labour leadership in November 1961, this time by Anthony Greenwood.


title: Hugh Gaitskell

text: The Campaign for Democratic Socialism was founded to promote the Gaitskellite cause – it never acquired much influence in the ranks of the trades unions, but achieved some success in promoting the selection of friendly Parliamentary candidates. Many of the younger CDS members would later be among the founding members of the breakaway Social Democratic Party (SDP) in 1981.


title: Hugh Gaitskell

text: Richard Hamilton with his wife, Terry Hamilton, both supporters of Campaign for Nuclear Disarmament, collaborated to produce "Portrait of Hugh Gaitskell as a Famous Monster of Filmland", 1964, with Richard completing the piece in 1964 after Terry's death in 1962. Arts Council England bought the piece for the national collection, which caused controversy. The painting was considered a tasteless attack. Hamilton stated in his posthumously published autobiography (written in the third person)


title: Hugh Gaitskell

text: 'When it was completed he was unhappy about the result. The painting did not have the aggression he had intended or the stylistic polarity he had aimed at. It was perhaps too smart-alecky, too clever: sarcasm was not the right tool for a subject that affected all humanity.'


title: Hugh Gaitskell

text: Gaitskell alienated some of his supporters by his opposition to British membership of the European Economic Community, which Conservative Prime Minister Macmillan had been seeking since July 1961. Although not entirely opposed in principle to British entry, he believed that the EEC was resistant to reform and that membership would hurt Britain's relations with the Commonwealth.


title: Hugh Gaitskell

text: In a speech to the party conference in October 1962, Gaitskell argued that if the aim was for Britain to participate in a Federal Europe, this would mean "the end of Britain as an independent European state, the end of a thousand years of history!" He added: "You may say, all right! Let it end! But, my goodness, it's a decision that needs a little care and thought."


title: Hugh Gaitskell

text: In the speech Gaitskell summoned up the memory of Vimy Ridge and Gallipoli, where Canadian and ANZAC troops had fought alongside British, mixing his defence of national identity with the tradition of the Commonwealth. The speech dismayed many of Gaitskell's natural supporters but was applauded by many on the Left, causing his wife Dora to observe "all the wrong people are cheering".


title: Hugh Gaitskell

text: In mid-December 1962, Gaitskell fell ill with flu, but he was declared well enough by his doctor to travel to the Soviet Union, where he met the Soviet leader Nikita Khrushchev for talks. Upon his return to Britain his condition deteriorated after he contracted another virus. On 4 January 1963 he was admitted to Middlesex Hospital in Marylebone, where, despite enormous efforts by doctors to save his life, he died on 18 January, with his wife at his bedside. He had died from complications following a sudden flare-up of lupus, an autoimmune disease which had affected his heart and kidneys. He was 56. Gaitskell's body was cremated at Golders Green Crematorium. His ashes are buried in the churchyard of St John-at-Hampstead Church, north London. His wife died in 1989 and was buried alongside him.


title: Hugh Gaitskell

text: The shock of Gaitskell's death was comparable to that of the sudden death of the later Labour Party leader John Smith, in May 1994, when he too seemed to be on the threshold of 10 Downing Street. Gaitskell had inherited £14,000 (around £800,000 at 2015 prices) from an aunt in April 1938, which was invested for him and multiplied several times (at a time of relatively high inflation) by a friend in the city. Gaitskell appears to have largely ignored this sum of capital, and his wife had no idea of his wealth. His estate was valued for probate at £80,013-10s-0d on 23 April 1963 (around £1.7m at 2020 prices).


title: Hugh Gaitskell

text: Beginning with his time as a minister under Attlee, Gaitskell kept a diary until 1956. The diary is an important primary source for the politics of the era.


title: Hugh Gaitskell

text: Gaitskell's death left an opening for Harold Wilson in the party leadership; Wilson narrowly won the next general election for Labour 21 months later. The abrupt and unexpected nature of Gaitskell's death led to some speculation that foul play might have been involved. The most popular conspiracy theory involved a supposed Soviet KGB plot to ensure that Wilson (alleged by the supporters of these theories to be a KGB agent himself) became Prime Minister. This claim was given new life by Peter Wright's controversial 1987 book "Spycatcher", but the only evidence that ever came to light was the testimony of a Soviet defector, Anatoliy Golitsyn. MI5 repeatedly investigated Wilson over the course of several years before conclusively deciding that he had no relationship with the KGB.


title: Hugh Gaitskell

text: Gaitskell was adored by followers like Roy Jenkins, who thought him a beacon of hope, decency and integrity, especially as Wilson's government came more and more to seem one of shabby compromises. Left-wingers like Barbara Castle loathed him for his intransigence. Many, including Tony Benn – a Labour centrist at the time – simply thought him a divisive figure and initially welcomed Wilson as a fresh start who could unite the party. In the event Wilson's closest allies as Prime Minister – Crossman and Castle – were former Bevanites.


title: Hugh Gaitskell

text: However, many of the Gaitskellites held leading positions in Harold Wilson's Cabinet of 1964–70. Many of them – e.g. Roy Jenkins and Bill Rodgers but not Anthony Crosland or Douglas Jay – became supporters of British membership of the EEC, an issue on which Labour was split in the 1970s and which helped to precipitate the SDP split of 1981.


title: Hugh Gaitskell

text: John Campbell writes that "the echoes of the Gaitskell-Bevan rivalry continued to divide the party right up to the 1980s". Neil Kinnock (Labour Leader 1983–92) grew up in South Wales and was brought up as an admirer of Bevan, but although he disliked the comparison his battle with the hard-left Militant tendency in the mid-1980s had echoes of Gaitskellism; John Smith (Labour Leader 1992–4) had been a Gaitskellite as a young man in the early 1960s; Tony Blair's first act as leader in 1994 was finally to abolish Clause IV – for this and other acts he was supported by the elderly Roy Jenkins, who had become a Liberal Democrat by then. Like Gaitskell before him, Blair was often seen by many of his enemies in the Labour Party as a public-school educated, middle-class interloper.


title: Hugh Gaitskell

text: Tony Benn contrasted Gaitskell's stand on the Suez Crisis to that of the former British Prime Minister Tony Blair on the war in Iraq. Margaret Thatcher compared Blair with Gaitskell in a different manner, warning her party when Blair came to power that he was the most formidable Labour leader since Hugh Gaitskell.


title: Hugh Gaitskell

text: Gaitskell's socialism was, in Campbell's view, that of a public servant wanting to see the world more rationally governed. Gaitskell very likely might have become Prime Minister had he lived; however, he left no lasting monument other than "the fading memory of promise unfulfilled". Gaitskell, although no Marxist, was a sincere socialist but nonetheless was in some respects the first "moderniser" who saw how Labour would have to adapt to survive.


title: Hugh Gaitskell

text: His longtime close friend Roy Jenkins concluded a decade afterwards, in an article which he later quoted in his memoirs:


title: Hugh Gaitskell

text: Because he never became Prime Minister, and because of the great capacity many considered that he had for the post, Hugh Gaitskell is remembered largely with respect from people both within and outside of the Labour Party. Gaitskell is regarded by some as "the best Prime Minister we never had".


title: Hugh Gaitskell

text: Brivati acknowledged that he had "an almost reckless honesty and courage" which could turn into stubbornness. "His leadership was a heroic failure" and "The defining moment of the post-war history of the Labour Party". Although by 1963 Gaitskell appeared to be on the verge of leading Labour back into power, it still took what Brivati describes as "the greatest performance by a leader of the opposition [last] century" for Harold Wilson to lead Labour back by a narrow majority.


title: Hugh Gaitskell

text: Brivati writes that for Gaitskell "socialism was not an end state … but the reform of institutions and practices for the more effective realisation of preferred values". Evan Durbin's "Politics of Democratic Socialism" (1940) was a seminal text. Gaitskell was not, in Brivati's view, a "progressive" in any modern sense. He favoured equality and thought the free market wasteful. He wanted to incorporate Liberal opinion within the Labour vote. However, the modernising leaders of subsequent generations, Neil Kinnock and Tony Blair, were to a certain extent continuing Gaitskell's tradition.


title: Hugh Gaitskell

text: His name appears in popular culture from time to time. For example, 'Hugh Gaitskell House' is the building Nicholas Lyndhurst's character Garry Sparrow is looking for in "Goodnight Sweetheart" when he first stumbles into Second World War London. A tower block of that name can be found opposite Stoke Newington railway station in North London.


title: Hugh Gaitskell

text: Hugh Gaitskell Primary School is situated in Beeston, part of his former Leeds South constituency. The area is now in the Leeds Central constituency, represented by Hilary Benn.


title: Hugh Gaitskell

text: In 1978, some 15 years after his death, a new housing development by Sandwell council in the Tividale area of the West Midlands was named Gaitskell Terrace.


title: Hugh Gaitskell

text: Gaitskell was buried in Hampstead, and a memorial plaque to his name is prominently placed in the cloisters of New College, Oxford.


title: Surplus value

text: In Marxian economics, surplus value is the difference between the amount raised through a sale of a product and the amount it cost to the owner of that product to manufacture it: i.e. the amount raised through sale of the product minus the cost of the materials, plant and labour power. The concept originated in Ricardian socialism, with the term "surplus value" itself being coined by William Thompson in 1824; however, it was not consistently distinguished from the related concepts of surplus labor and surplus product. The concept was subsequently developed and popularized by Karl Marx. Marx's formulation is the standard sense and the primary basis for further developments, though how much of Marx's concept is original and distinct from the Ricardian concept is disputed (see ). Marx's term is the German word ""Mehrwert"", which simply means value added (sales revenue minus the cost of materials used up), and is cognate to English "more worth".


title: Surplus value

text: It is a major concept in Karl Marx's critique of political economy. Conventionally, value-added is equal to the sum of gross wage income and gross profit income. However, Marx uses the term "Mehrwert" to describe the yield, profit or return on production capital invested, i.e. the amount of the increase in the value of capital. Hence, Marx's use of "Mehrwert" has always been translated as "surplus value", distinguishing it from "value-added". According to Marx's theory, surplus value is equal to the new value created by workers in excess of their own labor-cost, which is appropriated by the capitalist as profit when products are sold. Marx thought that the gigantic increase in wealth and population from the 19th century onwards was mainly due to the competitive striving to obtain "maximum surplus-value from the employment of labor", resulting in an equally gigantic increase of productivity and capital resources. To the extent that increasingly the economic surplus is convertible into money and expressed in money, the amassment of wealth is possible on a larger and larger scale (see capital accumulation and surplus product). The concept is closely connected to producer surplus.


title: Surplus value

text: By the Age of Enlightenment in the 18th century the French physiocrats were already writing on the surplus value that was being extracted from labor by "the employer, the owner, and all exploiters" although they used the term "net product". The concept of surplus value continued to be developed under Adam Smith who also used the term "net product" while his successors the Ricardian socialists, began using the term "surplus value" decades later after its coinage by William Thompson in 1824.


title: Surplus value

text: William Godwin and Charles Hall are also credited as earlier developers of the concept. Early authors also used the terms "surplus labor" and "surplus produce" (in Marx's language, surplus product), which have distinct meanings in Marxian economics: surplus labor "produces" surplus product, which has surplus value. Some authors consider Marx as completely borrowing from Thompson, notably Anton Menger:


title: Surplus value

text: This claim of priority has been vigorously contested, notably in an article by Friedrich Engels, completed by Karl Kautsky and published anonymously in 1887, reacting to and criticizing Menger in a review of his "The Right to the Whole Produce of Labour", arguing that there is nothing in common but the term "surplus value" itself.


title: Surplus value

text: An intermediate position acknowledges the early development by Ricardian socialists and others, but credits Marx with substantial development. For example:


title: Surplus value

text: Johann Karl Rodbertus developed a theory of surplus value in the 1830s and 1840s, notably in "Zur Erkenntnis unserer staatswirthschaftlichen Zustände" ("Toward an appreciation of our economic circumstances", 1842), and claimed earlier priority to Marx, specifically to have "shown practically in the same way as Marx, only more briefly and clearly, the source of the surplus value of the capitalists". The debate, taking the side of Marx's priority, is detailed in the Preface to "Capital, Volume II" by Engels.


title: Surplus value

text: Marx first elaborated his doctrine of surplus value in 1857–58 manuscripts of "A Contribution to the Critique of Political Economy" (1859), following earlier developments in his 1840s writings. It forms the subject of his 1862–63 manuscript "Theories of Surplus Value" (which was subsequently published as "Capital, Volume IV"), and features in his "Capital, Volume I" (1867).


title: Surplus value

text: Marx's solution was first to distinguish between labor-time worked and labor power, and secondly to distinguish between "absolute surplus value" and "relative surplus value". A worker who is sufficiently productive can produce an output value greater than what it costs to hire him. Although his wage seems to be based on hours worked, in an economic sense this wage does not reflect the full value of what the worker produces. Effectively it is not labour which the worker sells, but his capacity to work.


title: Surplus value

text: Imagine a worker who is hired for an hour and paid $10 per hour. Once in the capitalist's employ, the capitalist can have him operate a boot-making machine with which the worker produces $10 worth of work every 15 minutes. Every hour, the capitalist receives $40 worth of work and only pays the worker $10, capturing the remaining $30 as gross revenue. Once the capitalist has deducted fixed and variable operating costs of (say) $20 (leather, depreciation of the machine, etc.), he is left with $10. Thus, for an outlay of capital of $30, the capitalist obtains a surplus value of $10; his capital has not only been replaced by the operation, but also has increased by $10.


title: Surplus value

text: This "simple" exploitation characterizes the realization of "absolute surplus value", which is then claimed by the capitalist. The worker cannot capture this benefit directly because he has no claim to the means of production (e.g. the boot-making machine) or to its products, and his capacity to bargain over wages is restricted by laws and the supply/demand for wage labour. This form of exploitation was well understood by pre-Marxian Socialists and left-wing followers of Ricardo, such as Proudhon, and by early labor organizers, who sought to unite workers in unions capable of collective bargaining, in order to gain a share of profits and limit the length of the working day.


title: Surplus value

text: "Relative" surplus value is not created in a single enterprise or site of production. It arises instead from the total relation between multiple enterprises and multiple branches of industry when the necessary labor-time of production is reduced, effecting a change in the value of labor-power. For example, when new technology or new business practices increase the productivity of labor a capitalist already employs, or when the commodities necessary for workers' subsistence fall in value, the amount of socially necessary labor-time is decreased, the value of labor-power is reduced, and a relative surplus value is realized as profit for the capitalist, increasing the overall general rate of surplus value in the total economy.


title: Surplus value

text: "Total" surplus-value in an economy (Marx refers to the "mass" or volume of surplus-value) is basically equal to the sum of net distributed and undistributed profit, net interest, net rents, net tax on production and various net receipts associated with royalties, licensing, leasing, certain honorariums etc. (see also value product).


title: Surplus value

text: Of course, the way generic profit income is grossed and netted in social accounting may differ somewhat from the way an individual business does that (see also Operating surplus).


title: Surplus value

text: Marx's own discussion focuses mainly on profit, interest and rent, largely ignoring taxation and royalty-type fees which were proportionally very small components of the national income when he lived. Over the last 150 years, however, the role of the state in the economy has increased in almost every country in the world. Around 1850, the average share of government spending in GDP (See also Government spending) in the advanced capitalist economies was around 5%; in 1870, a bit above 8%; on the eve of World War I, just under 10%; just before the outbreak of World War II, around 20%; by 1950, nearly 30%; and today the average is around 35–40%. (see for example Alan Turner Peacock, "The growth of public expenditure", in "Encyclopedia of Public Choice", Springer 2003, pp. 594–597).


title: Surplus value

text: Marx believed that the long-term historical tendency would be for differences in rates of surplus value between enterprises and economic sectors to level out, as Marx explains in two places in "Capital" Vol. 3:


title: Surplus value

text: Hence, he assumed a uniform rate of surplus value in his models of how surplus value would be shared out under competitive conditions.


title: Surplus value

text: Both in Das Kapital and in preparatory manuscripts such as the "Grundrisse" and "Results of the immediate process of production", Marx asserts that commerce by stages transforms a non-capitalist production process into a capitalist production process, integrating it fully into markets, so that all inputs and outputs become marketed goods or services. When that process is complete, according to Marx, the whole of production has become simultaneously a labor process creating use-values and a valorisation process creating new value, and more specifically a surplus-value appropriated as net income (see also capital accumulation).


title: Surplus value

text: Marx contends that the whole purpose of production in this situation becomes the growth of capital; i.e. that production of output becomes "conditional" on capital accumulation. If production becomes unprofitable, capital will be withdrawn from production sooner or later.


title: Surplus value

text: The implication is that the main driving force of capitalism becomes the quest to maximise the appropriation of surplus-value augmenting the stock of capital. The overriding motive behind efforts to economise resources and labor would thus be to obtain the maximum possible increase in income and capital assets ("business growth"), and provide a steady or growing return on investment.


title: Surplus value

text: According to Marx, "absolute surplus value" is obtained by increasing the amount of time worked per worker in an accounting period. Marx talks mainly about the length of the working day or week, but in modern times the concern is about the number of hours worked per year.


title: Surplus value

text: In many parts of the world, as productivity rose, the workweek decreased from 60 hours to 50, 40 or 35 hours.


title: Surplus value

text: The attempt to extract more and more surplus-value from labor on the one side, and on the other side the resistance to this exploitation, are according to Marx at the core of the conflict between social classes, which is sometimes muted or hidden, but at other times erupts in open class warfare and class struggle.


title: Surplus value

text: Marx distinguished sharply between value and price, in part because of the sharp distinction he draws between the "production of surplus-value" and the "realisation of profit income" (see also value-form). Output may be "produced" containing surplus-value (valorisation), but "selling" that output (realisation) is not at all an automatic process.


title: Surplus value

text: Until payment from sales is received, it is uncertain how much of the surplus-value produced will actually be realised as profit from sales. So, the magnitude of "profit realised" in the form of money and the magnitude of "surplus-value produced" in the form of products may differ greatly, depending on what happens to market prices and the vagaries of supply and demand fluctuations. This insight forms the basis of Marx's theory of market value, prices of production and the tendency of the rate of profit of different enterprises to be levelled out by competition.


title: Surplus value

text: In his published and unpublished manuscripts, Marx went into great detail to examine many different factors which could affect the production and realisation of surplus-value. He regarded this as crucial for the purpose of understanding the dynamics and dimensions of capitalist competition, not just business competition but also competition between capitalists and workers and among workers themselves. But his analysis did not go much beyond specifying some of the overall outcomes of the process.


title: Surplus value

text: His main conclusion though is that employers will aim to maximise the productivity of labour and economise on the use of labour, to reduce their unit-costs and maximise their net returns from sales at current market prices; at a given ruling market price for an output, every reduction of costs and every increase in productivity and sales turnover will increase profit income for that output. The main method is "mechanisation", which raises the fixed capital outlay in investment.


title: Surplus value

text: In turn, this causes the unit-values of commodities to decline over time, and a "decline of the average rate of profit" in the sphere of production occurs, culminating in a crisis of capital accumulation, in which a sharp reduction in productive investments combines with mass unemployment, followed by an intensive rationalisation process of take-overs, mergers, fusions, and restructuring aiming to restore profitability.


title: Surplus value

text: In general, business leaders and investors are hostile to any attempts to encroach on total profit volume, especially those of government taxation. The lower taxes are, other things being equal, the bigger the mass of profit that can be distributed as income to private investors. It was "tax revolts" that originally were a powerful stimulus motivating the bourgeoisie to wrest state power from the feudal aristocracy at the beginning of the capitalist era.


title: Surplus value

text: In reality, of course, a substantial portion of tax money is also "redistributed" to private enterprise in the form of government contracts and subsidies. Capitalists may therefore be in conflict among themselves about taxes, since what is a cost to some, is a source of profit to others. Marx never analysed all this in detail; but the concept of surplus value will apply mainly to taxes on gross income (personal and business income from production) and on the trade in products and services. Estate duty for example rarely contains a surplus value component, although profit could be earned in the transfer of the estate.


title: Surplus value

text: Generally, Marx seems to have regarded taxation imposts as a "form" which disguised real product "values". Apparently following this view, Ernest Mandel in his 1960 treatise "Marxist Economic Theory" refers to (indirect) taxes as "arbitrary additions to commodity prices". But this is something of a misnomer, and disregards that taxes become part of the normal cost-structure of production. In his later treatise on late capitalism, Mandel astonishingly hardly mentions the significance of taxation at all, a very serious omission from the point of view of the real world of modern capitalism since taxes can reach a magnitude of a third, or even half of GDP (see E. Mandel, "Late Capitalism". London: Verso, 1975).For example in the United Kingdom alone 75% of all taxation revenue comes from just three taxes Income tax, National insurance and VAT which in reality is 75% of the GDP of the country.


title: Surplus value

text: Generally, Marx focused in Das Kapital on the new surplus-value generated by production, and the distribution of this surplus value. In this way, he aimed to reveal the "origin of the wealth of nations" given a capitalist mode of production. However, in any real economy, a distinction must be drawn between the primary circuit of capital, and the secondary circuits. To some extent, national accounts also do this.


title: Surplus value

text: The primary circuit refers to the incomes and products generated and distributed from productive activity (reflected by GDP). The secondary circuits refer to trade, transfers and transactions occurring "outside" that sphere, which can also generate incomes, and these incomes may also involve the realisation of a surplus-value or profit.


title: Surplus value

text: It is true that Marx argues no net additions to value can be created through acts of exchange, economic value being an attribute of labour-products (previous or newly created) only. Nevertheless, trading activity outside the sphere of production can obviously also yield a surplus-value which represents a "transfer" of value from one person, country or institution to another.


title: Surplus value

text: A very simple example would be if somebody sold a second-hand asset at a profit. This transaction is not recorded in gross product measures (after all, it isn't new production), nevertheless a surplus-value is obtained from it. Another example would be capital gains from property sales. Marx occasionally refers to this kind of profit as "profit upon alienation", alienation being used here in the juridical, not sociological sense. By implication, if we just focused on surplus-value newly created in production, we would "underestimate" total surplus-values "realised as income" in a country. This becomes obvious if we compare census estimates of income & expenditure with GDP data.


title: Surplus value

text: This is another reason why surplus-value "produced" and surplus-value "realised" are two different things, although this point is largely ignored in the economics literature. But it becomes highly important when the real growth of production stagnates, and a growing portion of capital shifts out of the sphere of production in search of surplus-value from other deals.


title: Surplus value

text: Nowadays the volume of world trade grows significantly faster than GDP, suggesting to Marxian economists such as Samir Amin that surplus-value realised from commercial trade (representing to a large extent a transfer of value by intermediaries between producers and consumers) grows faster than surplus-value realised directly from production.


title: Surplus value

text: Thus, if we took the final price of a good (the cost to the final consumer) and analysed the cost structure of that good, we might find that, over a period of time, the direct producers get less income and intermediaries between producers and consumers (traders) get more income from it. That is, control over the "access" to a good, asset or resource as such may increasingly become a very important factor in realising a surplus-value. In the worst case, this amounts to parasitism or extortion. This analysis illustrates a key feature of surplus value which is that it accumulated by the owners of capital only within "inefficient" markets because only inefficient markets – i.e. those in which transparency and competition are low – have profit margins large enough to facilitate capital accumulation. Ironically, profitable – meaning inefficient – markets have difficulty meeting the definition a free market because a free market is to some extent defined as an efficient one: one in which goods or services are exchanged without coercion or fraud, or in other words with competition (to prevent monopolistic coercion) and transparency (to prevent fraud).


title: Surplus value

text: The first attempt to measure the rate of surplus-value in money-units was by Marx himself in chapter 9 of "Das Kapital", using factory data of a spinning mill supplied by Friedrich Engels (though Marx credits "a Manchester spinner"). Both in published and unpublished manuscripts, Marx examines variables affecting the rate and mass of surplus-value in detail.


title: Surplus value

text: Some Marxian economists argue that Marx thought the possibility of measuring surplus value depends on the publicly available data. We can develop statistical "indicators" of trends, without mistakenly conflating data with the real thing they represent, or postulating "perfect measurements or perfect data" in the empiricist manner.


title: Surplus value

text: Since early studies by Marxian economists like Eugen Varga, Charles Bettelheim, Joseph Gillmann, Edward Wolff and Shane Mage, there have been numerous attempts by Marxian economists to measure the trend in surplus-value statistically using national accounts data. The most convincing modern attempt is probably that of Anwar Shaikh and Ahmet Tonak.


title: Surplus value

text: Usually this type of research involves reworking the components of the official measures of gross output and capital outlays to approximate Marxian categories, in order to estimate empirically the trends in the ratios thought important in the Marxian explanation of capital accumulation and economic growth: the rate of surplus-value, the organic composition of capital, the rate of profit, the rate of increase in the capital stock, and the rate of reinvestment of realised surplus-value in production.


title: Surplus value

text: The Marxian mathematicians Emmanuel Farjoun and Moshé Machover argue that "even if the rate of surplus value has changed by 10–20% over a hundred years, the real problem [to explain] is why it has changed so little" (quoted from "The Laws of Chaos: A Probabilistic Approach to Political Economy" (1983), p. 192). The answer to that question must, in part, be sought in artifacts (statistical distortion effects) of data collection procedures. Mathematical extrapolations are ultimately based on the data available, but that data itself may be fragmentary and not the "complete picture".


title: Surplus value

text: In neo-Marxist thought, Paul A. Baran for example substitutes the concept of "economic surplus" for Marx's surplus value. In a joint work, Paul Baran and Paul Sweezy define the economic surplus as "the difference between what a society produces and the costs of producing it" ("Monopoly Capitalism", New York 1966, p. 9). Much depends here on how the costs are valued, and which costs are taken into account. Piero Sraffa also refers to a "physical surplus" with a similar meaning, calculated according to the relationship between prices of physical inputs and outputs.


title: Surplus value

text: In these theories, surplus product and surplus value are equated, while value and price are identical, but the "distribution" of the surplus tends to be separated theoretically from its "production"; whereas Marx insists that the distribution of wealth is governed by the social conditions in which it is "produced", especially by property relations giving entitlement to products, incomes and assets (see also relations of production).


title: Surplus value

text: This is a substantive – if abstract – thesis about the basic social relations involved in giving and getting, taking and receiving in human society, and their consequences for the way work and wealth is shared out. It suggests a "starting point" for an inquiry into the problem of social order and social change. But obviously it is "only" a starting point, not the whole story, which would include all the "variations and gradations".


title: Surplus value

text: A textbook-type example of an alternative interpretation to Marx's is provided by Lester Thurow. He argues: "In a capitalistic society, profits – and losses – hold center stage." But what, he asks, explains profits?


title: Surplus value

text: The problem here is that Thurow doesn't really provide an objective explanation of profits so much as a moral justification for profits, i.e. as a legitimate entitlement or claim, in return for the supply of capital.


title: Surplus value

text: He adds that "Attempts have been made to organize productive societies without the profit motive (...) [but] since the industrial revolution... there have been essentially no successful economies that have not taken advantage of the profit motive." The problem here is again a moral judgement, dependent on what you mean by success. Some societies using the profit motive were ruined; profit is no guarantee of success, although you can say that it has powerfully stimulated economic growth.


title: Surplus value

text: Thurow goes on to note that "When it comes to actually measuring profits, some difficult accounting issues arise." Why? Because after deduction of costs from gross income, "It is hard to say exactly how much must be reinvested to maintain the size of the capital stock". Ultimately, Thurow implies, the tax department is the arbiter of the profit volume, because it determines depreciation allowances and other costs which capitalists may annually deduct in calculating taxable gross income.


title: Surplus value

text: This is obviously a theory very different from Marx's. In Thurow's theory, the aim of business is to "maintain" the capital stock. In Marx's theory, competition, desire and market fluctuations create the striving and pressure to "increase" the capital stock; the whole aim of capitalist production is capital accumulation, i.e. business growth maximising net income. Marx argues there is no evidence that the "profit" accruing to capitalist owners is "quantitatively connected" to the "productive contribution" of the capital they own. In practice, within the capitalist firm, no standard procedure exists for measuring such a "productive contribution" and for distributing the residual income accordingly.


title: Surplus value

text: In Thurow's theory, profit is mainly just "something that happens" when costs are deducted from sales, or else a "justly deserved" income. For Marx, increasing profits is, at least in the longer term, the "bottom line" of business behaviour: the quest for obtaining extra surplus-value, and the incomes obtained from it, are what guides capitalist development (in modern language, "creating maximum shareholder value").


title: Surplus value

text: That quest, Marx notes, always involves a power relationship between different social classes and nations, inasmuch as attempts are made to force "other" people to pay for costs as much as possible, while maximising one's own entitlement or claims to "income" from economic activity. The clash of economic interests that invariably results, implies that the battle for surplus value will always involve an irreducible moral dimension; the whole process rests on complex system of negotiations, dealing and bargaining in which reasons for claims to wealth are asserted, usually within a legal framework and sometimes through wars. Underneath it all, Marx argues, was an exploitative relationship.


title: Surplus value

text: That was the main reason why, Marx argues, the real sources of surplus-value were shrouded or obscured by ideology, and why Marx thought that political economy merited a critique. Quite simply, economics proved unable to theorise capitalism as a "social system", at least not without moral biases intruding in the very "definition" of its conceptual distinctions. Hence, even the most simple economic concepts were often riddled with contradictions. But market trade could function fine, even if the "theory" of markets was false; all that was required was an agreed and legally enforceable accounting system. On this point, Marx probably would have agreed with Austrian School economics – no knowledge of "markets in general" is required to participate in markets.


title: Adam Gase

text: Adam Joseph Gase (born March 29, 1978) is a former American football coach in the National Football League (NFL). He came to prominence as the offensive coordinator for the Denver Broncos from 2013 to 2014, whose offense set the NFL record for points scored in 2013 and helped the team reach Super Bowl XLVIII. Following this success, Gase served as the head coach of the Miami Dolphins from 2016 to 2018 and the New York Jets from 2019 to 2020.


title: Adam Gase

text: Gase began his coaching career at Michigan State while an undergraduate student. He was a student assistant to the coaching staff.


title: Adam Gase

text: When Gase graduated from Michigan State, he followed coach Nick Saban to LSU for the 2000 season. In Gase's first season with LSU, he worked as a defensive graduate assistant and worked with recruiting. For the next two seasons, Gase worked full-time as a recruiting assistant for the Tigers. The season after Gase left, LSU won a national championship.


title: Adam Gase

text: Gase left LSU and the college ranks to become a scouting assistant for the Detroit Lions. He was hired by Steve Mariucci. Gase worked as a scouting assistant from 2003 to 2005. He also added the role of offensive assistant for the 2005 season.


title: Adam Gase

text: Gase stayed with the Lions under new head coach Rod Marinelli and was promoted to the team's offensive quality control coach for the 2006 season. In 2007, Mike Martz promoted Gase to the team's quarterbacks coach.


title: Adam Gase

text: In 2008, Gase joined Mike Martz as an offensive assistant coach for the San Francisco 49ers as the team went 7-9.


title: Adam Gase

text: As the offensive coordinator of the Denver Broncos under John Fox, Gase was on the sidelines during Peyton Manning's record-breaking passing season in 2013. Gase and the Broncos appeared in Super Bowl XLVIII but fell to the Seattle Seahawks in a 43–8 blowout loss. After the successful 2013 season, Gase stayed on as the offensive coordinator for the 2014 season. The season after Gase left, the Denver Broncos won Super Bowl 50.


title: Adam Gase

text: After the Chicago Bears hired John Fox as their new head coach, Gase joined the team as Fox's offensive coordinator once again. In Gase's only season as the Bears offensive coordinator, the team finished 18th in total offense, while also recording 5,514 total net yards and 344.6 per game, while finishing 6-10.


title: Adam Gase

text: The Miami Dolphins announced that Gase would be the 12th head coach in franchise history on January 9, 2016. He is the first to be born after the team was founded in 1966. The Dolphins started the season with a 1–4 record, but would follow that up with a six-game winning streak. Gase finished his first season as head coach with a 10–6 record leading Miami to the playoffs for the first time since 2008. Miami finished second in the AFC East behind the eventual Super Bowl LI champion New England Patriots. In Gase's first career playoff game as head coach, the Dolphins lost to the Pittsburgh Steelers by a score of 30–12 in the Wild Card round.


title: Adam Gase

text: On December 31, 2018, a day after a 42–17 loss to the Buffalo Bills to close out the 2018 season, the Dolphins fired Gase as part of their organizational changes. He finished with a 23–25 regular-season record as Miami's head coach.


title: Adam Gase

text: The New York Jets announced that Gase would be the 19th head coach in the team's history on January 11, 2019. On May 15, general manager Mike Maccagnan was fired and Gase was named interim general manager; Gase retained the role until Joe Douglas was hired as the permanent general manager on June 6.


title: Adam Gase

text: In Gase's first year, the Jets stumbled to a 1–7 record through the first eight games with starting quarterback Sam Darnold missing three games after coming down with mononucleosis, but won six of their final eight games to finish at 7–9.


title: Adam Gase

text: In his second year, Gase and the Jets started 0–13, the worst such start in franchise history. By the Week 7 matchup against the Buffalo Bills, Gase had relieved himself of offensive play calling duties in favor of offensive coordinator Dowell Loggains. It was rumored that Gase would return to calling offensive plays for the Week 12 game against the Miami Dolphins in the 20–3 loss. At the postgame press conference, Gase did not give a straightforward answer on who was calling the plays.


title: Adam Gase

text: In Week 13, Gase fired defensive coordinator Gregg Williams for making the "Cover 0 blitz" play call that cost the Jets the win against the Las Vegas Raiders. After starting the season 0–13, the Jets won their first game of 2020 on December 20, defeating the Los Angeles Rams 23–20. The Jets finished the season at the bottom of the AFC East with a 2–14 record, one win better than their franchise-worst 1–15 record in 1996. On January 3, 2021, hours after the team's season-ending loss against the Patriots, Gase was fired by the Jets. Gase finished his tenure in New York with a 9–23 (.281) regular season record.


title: Adam Gase

text: Gase is married to Jennifer Vitt, the daughter of former NFL linebacker coach Joe Vitt. The couple have three children together. Gase is a fan of the Detroit Tigers.


title: Telephone exchange

text: A telephone exchange, telephone switch, or central office is a telecommunications system used in the public switched telephone network (PSTN) or in large enterprises. It interconnects telephone subscriber lines or virtual circuits of digital systems to establish telephone calls between subscribers.


title: Telephone exchange

text: In historical perspective, telecommunication terms have been used with different semantics over time. The term "telephone exchange" is often used synonymously with "central office", a Bell System term. Often, a "central office" is defined as a building used to house the inside plant equipment of potentially several telephone exchanges, each serving a certain geographical area. Such an area has also been referred to as the exchange or exchange area. In North America, a central office location may also be identified as a "wire center", designating a facility to which a telephone is connected and obtains dial tone. For business and billing purposes, telecommunication carriers define "rate centers", which in larger cities may be clusters of central offices, to define specified geographical locations for determining distance measurements.


title: Telephone exchange

text: In the United States and Canada, the Bell System established in the 1940s a uniform nationwide numbering system of identifying central offices with a three-digit central office code and a three-digit numbering plan area code (NPA code, or area code). Central office codes were unique in each numbering plan area. The NPA code and the central office code were used as prefixes in subscriber telephone numbers. With the development of international and transoceanic telephone trunks, especially driven by direct customer dialing, similar efforts of systematic organization of the telephone networks occurred in many countries in the mid-20th century.


title: Telephone exchange

text: For corporate or enterprise use, a private telephone exchange is often referred to as a private branch exchange (PBX), when it has connections to the public switched telephone network. A PBX is installed in enterprise facilities, typically near large office spaces or within an organizational campus to serve the organization's telephones and any private leased line circuits. Smaller installations might deploy a PBX or key telephone system in the office of a receptionist.


title: Telephone exchange

text: In the era of the electrical telegraph, its principal users were post offices, railway stations, the more important governmental centers (ministries), stock exchanges, very few nationally distributed newspapers, the largest internationally important corporations, and wealthy individuals. Despite the fact that telephone devices existed before the invention of the telephone exchange, their success and economical operation would have been impossible on the same schema and structure of the contemporary telegraph, as prior to the invention of the telephone exchange switchboard, early telephones were hardwired to and communicated with only a single other telephone (such as from an individual's home to the person's business).


title: Telephone exchange

text: A telephone exchange is a telephone system for a small geographic area that provides the switching (interconnection) of subscriber lines for calls made between them. Telephone exchanges replaced small telephone systems that connected its users with direct lines between each and every subscriber station. Exchanges made telephony an available and comfortable technology for everyday use and it gave the impetus for the creation of a new industrial sector.


title: Telephone exchange

text: As with the invention of the telephone itself, the honour of "first telephone exchange" has several claimants. One of the first to propose a telephone exchange was Hungarian Tivadar Puskás in 1877 while he was working for Thomas Edison. The first experimental telephone exchange was based on the ideas of Puskás, and it was built by the Bell Telephone Company in Boston in 1877. The world's first state-administered telephone exchange opened on November 12, 1877 in Friedrichsberg close to Berlin under the direction of Heinrich von Stephan. George W. Coy designed and built the first commercial US telephone exchange which opened in New Haven, Connecticut in January, 1878, and the first telephone booth was built in nearby Bridgeport. The switchboard was built from "carriage bolts, handles from teapot lids and bustle wire" and could handle two simultaneous conversations. Charles Glidden is also credited with establishing an exchange in Lowell, MA. with 50 subscribers in 1878.


title: Telephone exchange

text: In Europe other early telephone exchanges were based in London and Manchester, both of which opened under Bell patents in 1879. Belgium had its first International Bell exchange (in Antwerp) a year later.


title: Telephone exchange

text: Later exchanges consisted of one to several hundred plug boards staffed by switchboard operators. Each operator sat in front of a vertical panel containing banks of ¼-inch tip-ring-sleeve (3-conductor) jacks, each of which was the local termination of a subscriber's telephone line. In front of the jack panel lay a horizontal panel containing two rows of patch cords, each pair connected to a cord circuit.


title: Telephone exchange

text: When a calling party lifted the receiver, the local loop current lit a signal lamp near the jack. The operator responded by inserting the rear cord ("answering cord") into the subscriber's jack and switched her headset into the circuit to ask, "Number, please?" For a local call, the operator inserted the front cord of the pair ("ringing cord") into the called party's local jack and started the ringing cycle. For a long-distance call, she plugged into a trunk circuit to connect to another operator in another bank of boards or at a remote central office. In 1918, the average time to complete the connection for a long-distance call was 15 minutes.


title: Telephone exchange

text: Early manual switchboards required the operator to operate listening keys and ringing keys, but by the late 1910s and 1920s, advances in switchboard technology led to features which allowed the call to be automatically answered immediately as the operator inserted the answering cord, and ringing would automatically begin as soon as the operator inserted the ringing cord into the called party's jack. The operator would be disconnected from the circuit, allowing her to handle another call, while the caller heard an audible ringback signal, so that that operator would not have to periodically report that she was continuing to ring the line.


title: Telephone exchange

text: In the ringdown method, the originating operator called another intermediate operator who would call the called subscriber, or passed it on to another intermediate operator. This chain of intermediate operators could complete the call only if intermediate trunk lines were available between all the centers at the same time. In 1943 when military calls had priority, a cross-country US call might take as long as 2 hours to request and schedule in cities that used manual switchboards for toll calls.


title: Telephone exchange

text: On March 10, 1891, Almon Brown Strowger, an undertaker in Kansas City, Missouri, patented the stepping switch, a device which led to the automation of telephone circuit switching. While there were many extensions and adaptations of this initial patent, the one best known consists of 10 levels or banks, each having 10 contacts arranged in a semicircle. When used with a rotary telephone dial, each pair of digits caused the shaft of the central contact "hand" of the stepping switch to first step (ratchet) up one level for each pulse in the first digit and then to swing horizontally in a contact row with one small rotation for each pulse in the next digit.


title: Telephone exchange

text: Later stepping switches were arranged in banks, the first stage of which was a "linefinder". If one of up to a hundred subscriber lines (two hundred lines in later linefinders) had the receiver lifted "off hook", a linefinder connected the subscriber's line to a free first selector, which returned the subscriber a dial tone to show that it was ready to receive dialled digits. The subscriber's dial pulsed at about 10 pulses per second, although the speed depended on the standard of the particular telephone administration.


title: Telephone exchange

text: Exchanges based on the Strowger switch were eventually challenged by other exchange types and later by crossbar technology. These exchange designs promised faster switching and would accept inter-switch pulses faster than the Strowger's typical 10 pps—typically about 20 pps. At a later date many also accepted DTMF "touch tones" or other tone signaling systems.


title: Telephone exchange

text: A transitional technology (from pulse to DTMF) had converters to convert DTMF to pulse, to feed to older Strowger, panel, or crossbar switches. This technology was used as late as mid-2002.


title: Telephone exchange

text: Many terms used in telecommunication technology differ in meaning and usage among the various English speaking regions.


title: Telephone exchange

text: A "central office" originally was a primary exchange in a city with other exchanges service parts of the area. The term became to mean any switching system including its facilities and operators. It is also used generally for the building that houses switching and related inside plant equipment. In United States telecommunication jargon, a central office (C.O.) is a common carrier switching center Class 5 telephone switch in which trunks and local loops are terminated and switched.


title: Telephone exchange

text: In the UK, a "telephone exchange" means an exchange building, and is also the name for a telephone switch.


title: Telephone exchange

text: With manual service, the customer lifts the receiver off-hook and asks the operator to connect the call to a requested number. Provided that the number is in the same central office, and located on the operator's switchboard, the operator connects the call by plugging the ringing cord into the jack corresponding to the called customer's line. If the called party's line is on a different switchboard in the same office, or in a different central office, the operator plugs into the trunk for the destination switchboard or office and asks the operator answering (known as the "B" operator) to connect the call.


title: Telephone exchange

text: Most urban exchanges provided common-battery service, meaning that the central office provided power to the subscriber telephone circuits for operation of the transmitter, as well as for automatic signaling with rotary dials. In common-battery systems, the pair of wires from a subscriber's telephone to the exchange carry 48V (nominal) DC potential from the telephone company end across the conductors. The telephone presents an open circuit when it is on-hook or idle.


title: Telephone exchange

text: When a subscriber's phone is off-hook, it presents an electrical resistance across the line which causes current to flow through the telephone and wires to the central office. In a manually operated switchboard, this current flowed through a relay coil, and actuated a buzzer or a lamp on the operator's switchboard, signaling the operator to perform service.


title: Telephone exchange

text: In the largest cities, it took many years to convert every office to automatic equipment, such as a panel switch. During this transition period, once numbers were standardized to the 2L-4N or 2L-5N format (two-letter exchange name and either four or five digits), it was possible to dial a number located in a manual exchange and be connected without requesting operator assistance. The policy of the Bell System stated that customers in large cities should not need to be concerned with the type of office, whether they were calling a manual or an automatic office.


title: Telephone exchange

text: When a subscriber dialed the number of a manual station, an operator at the destination office answered the call after seeing the number on an indicator, and connected the call by plugging a cord into the outgoing circuit and ringing the destination station. For example, if a dial customer calling from TAylor 4725 dialed a number served by a manual exchange, e.g., ADams 1383-W, the call was completed, from the subscriber's perspective, exactly as a call to LEnnox 5813, in an automated exchange. The party line letters W, R, J, and M were only used in manual exchanges with jack-per-line party lines.


title: Telephone exchange

text: In contrast to the listing format "MAin 1234" for an automated office with two capital letters, a manual office, having listings such as Hillside 834 or East 23, was recognizable by the format in which the second letter was not capitalized.


title: Telephone exchange

text: Rural areas, as well as the smallest towns, had manual service and signaling was accomplished with magneto telephones, which had a crank for the signaling generator. To alert the operator, or another subscriber on the same line, the subscriber turned the crank to generate ringing current. The switchboard responded by interrupting the circuit, which dropped a metal tab above the subscriber's line jack and sounded a buzzer. Dry cell batteries, normally two large N°. 6 cells in the subscriber's telephone, provided the direct current for the transmitter. Such magneto systems were in use in the US as late as 1983, as in the small town, Bryant Pond, Woodstock, Maine.


title: Telephone exchange

text: Many small town magneto systems featured party lines, anywhere from two to ten or more subscribers sharing a single line. When calling a party, the operator used code ringing, a distinctive ringing signal sequence, such as two long rings followed by one short ring. Everyone on the line could hear the signals, and could pick up and monitor other people's conversations.


title: Telephone exchange

text: Automatic exchanges, which provided dial service, were invented by Almon Strowger in 1888. First used commercially in 1892, they did not gain widespread use until the first decade of the 20th century. They eliminated the need for human switchboard operators who completed the connections required for a telephone call. Automation replaced human operators with electromechanical systems, and telephones were equipped with a dial by which a caller transmitted the destination telephone number to the automatic switching system.


title: Telephone exchange

text: A telephone exchange automatically senses an off-hook condition of the telephone when the user removes the handset from the switchhook or cradle. The exchange provides dial tone at that time to indicate to the user that the exchange is ready to receive dialed digits. The pulses or DTMF tones generated by the telephone are processed and a connection is established to the destination telephone within the same exchange or to another distant exchange.


title: Telephone exchange

text: The exchange maintains the connection until one of the parties hangs up. This monitoring of connection status is called "supervision." Additional features, such as billing equipment, may also be incorporated into the exchange.


title: Telephone exchange

text: The Bell System dial service implemented a feature called automatic number identification (ANI) which facilitated services like automated billing, toll-free 800-numbers, and 9-1-1 service. In manual service, the operator knows where a call is originating by the light on the switchboard jack field. Before ANI, long-distance calls were placed into an operator queue and the operator asked the calling party's number and recorded it on a paper toll ticket.


title: Telephone exchange

text: Early exchanges were electromechanical systems using motors, shaft drives, rotating switches and relays. Some types of automatic exchanges were the Strowger switch or step-by-step switch, All Relay, panel switch, Rotary system and the crossbar switch.


title: Telephone exchange

text: Circuits interconnecting switches are called "trunks". Before Signalling System 7, Bell System electromechanical switches in the United States originally communicated with one another over trunks using a variety of DC voltages and signaling tones, replaced today by digital signals.


title: Telephone exchange

text: Some signaling communicated dialed digits. An early form called Panel Call Indicator Pulsing used quaternary pulses to set up calls between a panel switch and a manual switchboard. Probably the most common form of communicating dialed digits between electromechanical switches was sending dial pulses, equivalent to a rotary dial's pulsing, but sent over trunk circuits between switches.


title: Telephone exchange

text: In Bell System trunks, it was common to use 20 pulse-per-second between crossbar switches and crossbar tandems. This was twice the rate of Western Electric/Bell System telephone dials. Using the faster pulsing rate made trunk utilization more efficient because the switch spent half as long listening to digits. DTMF was not used for trunk signaling.


title: Telephone exchange

text: Multi-frequency (MF) was the last of the pre-digital methods. It used a different set of tones sent in pairs like DTMF. Dialing was preceded by a special "keypulse" (KP) signal and followed by a "start" (ST). Variations of the Bell System MF tone scheme became a CCITT standard. Similar schemes were used in the Americas and in some European countries including Spain. Digit strings between switches were often abbreviated to further improve utilization.


title: Telephone exchange

text: For example, one switch might send only the last four or five digits of a telephone number. In one case, seven digit numbers were preceded by a digit 1 or 2 to differentiate between two area codes or office codes, (a two-digit-per-call savings). This improved revenue per trunk and reduced the number of digit receivers needed in a switch. Every task in electromechanical switches was done in big metallic pieces of hardware. Every fractional second cut off of call set up time meant fewer racks of equipment to handle call traffic.


title: Telephone exchange

text: Examples of signals communicating supervision or call progress include E and M signaling, SF signaling, and robbed-bit signaling. In physical (not carrier) E and M trunk circuits, trunks were four wire. Fifty trunks would require a hundred pair cable between switches, for example. Conductors in one common circuit configuration were named tip, ring, ear (E) and mouth (M). Tip and ring were the voice-carrying pair, and named after the tip and ring on the three conductor cords on the manual operator's console.


title: Telephone exchange

text: In two-way trunks with E and M signaling, a handshake took place to prevent both switches from colliding by dialing calls on the same trunk at the same time. By changing the state of these leads from ground to -48 volts, the switches stepped through a handshake protocol. Using DC voltage changes, the local switch would send a signal to get ready for a call and the remote switch would reply with an acknowledgment (a wink) to go ahead with dial pulsing. This was done with relay logic and discrete electronics.


title: Telephone exchange

text: These voltage changes on the trunk circuit would cause pops or clicks that were audible to the subscriber as the electrical handshaking stepped through its protocol. Another handshake, to start timing for billing purposes, caused a second set of clunks when the called party answered.


title: Telephone exchange

text: A second common form of signaling for supervision was called single-frequency or "SF signaling". The most common form of this used a steady 2,600 Hz tone to identify a trunk as idle. Trunk circuitry hearing a 2,600 Hz tone for a certain duration would go idle. (The duration requirement reduced falsing.) Some systems used tone frequencies over 3,000 Hz, particularly on SSB frequency-division multiplex microwave radio relays.


title: Telephone exchange

text: On T-carrier digital transmission systems, bits within the T-1 data stream were used to transmit supervision. By careful design, the appropriated bits did not change voice quality appreciably. Robbed bits were translated to changes in contact states (opens and closures) by electronics in the channel bank hardware. This allowed direct current E and M signaling, or dial pulses, to be sent between electromechanical switches over a digital carrier which did not have DC continuity.


title: Telephone exchange

text: A characteristic of electromechanical switching equipment is that the maintenance staff could hear the mechanical clattering of Strowgers, panel switches or crossbar relays. During heavy use periods, it could be difficult to converse in a central office switch room due to the clatter of calls being processed in a large switch. For example, on Mother's Day in the US, or on a Friday evening around 5pm, the metallic rattling could make raised voices necessary. For wire spring relay markers these noises resembled hail falling on a metallic roof.


title: Telephone exchange

text: On a pre-dawn Sunday morning, call processing might slow to the extent that one might be able to hear individual calls being dialed and set up. There were also noises from whining power inverters and whirring ringing generators. Some systems had a continual, rhythmic "clack-clack-clack" from wire spring relays that made reorder (120 ipm) and busy (60 ipm) signals.


title: Telephone exchange

text: Bell System installations typically had alarm bells, gongs, or chimes to announce alarms calling attention to a failed switch element. A trouble reporting card system was connected to switch common control elements. These trouble reporting systems punctured cardboard cards with a code that logged the nature of a failure. Reed relay technology in stored program control exchange finally quieted the environment.


title: Telephone exchange

text: Electromechanical switching systems required sources of electricity in form of direct current (DC), as well as alternating ring current (AC), which were generated on-site with mechanical generators. In addition, telephone switches required adjustment of many mechanical parts. Unlike modern switches, a circuit connecting a dialed call through an electromechanical switch had DC continuity within the local exchange area via metallic conductors.


title: Telephone exchange

text: The design and maintenance procedures of all systems involved methods to avoid that subscribers experienced undue changes in the quality of the service or that they noticed failures. A variety of tools referred to as "make-busy"s were plugged into electromechanical switch elements upon failure and during repairs. A make-busy identified the part being worked on as in-use, causing the switching logic to route around it. A similar tool was called a "TD tool." Delinquent subscribers had their service temporarily denied (TDed). This was effected by plugging a tool into the subscriber's office equipment on Crossbar systems or line group in step-by-step switches. The subscriber could receive calls but could not dial out.


title: Telephone exchange

text: Strowger-based, step-by-step offices in the Bell System required continuous maintenance, such as cleaning. Indicator lights on equipment bays alerted staff to conditions such as blown fuses (usually white lamps) or a permanent signal (stuck off-hook condition, usually green indicators). Step offices were more susceptible to single-point failures than newer technologies.


title: Telephone exchange

text: Crossbar offices used more shared, common control circuits. For example, a digit receiver (part of an element called an "Originating Register") would be connected to a call just long enough to collect the subscriber's dialed digits. Crossbar architecture was more flexible than step offices. Later crossbar systems had punch-card-based trouble reporting systems. By the 1970s, "automatic number identification" had been retrofitted to nearly all step-by-step and crossbar switches in the Bell System.


title: Telephone exchange

text: Electronic switching systems gradually evolved in stages from electromechanical hybrids with stored program control to the fully digital systems. Early systems used reed relay-switched metallic paths under digital control. Equipment testing, phone numbers reassignments, circuit lockouts and similar tasks were accomplished by data entry on a terminal.


title: Telephone exchange

text: Examples of these systems included the Western Electric 1ESS switch, Northern Telecom SP1, Ericsson AXE, Automatic Electric EAX-1 & EAX-2, Philips PRX/A, ITT Metaconta, British GPO/BT TXE series and several other designs were similar. Ericsson also developed a fully computerized version of their ARF crossbar exchange called ARE. These used a crossbar switching matrix with a fully computerized control system and provided a wide range of advanced services. Local versions were called ARE11 while tandem versions were known as ARE13. They were used in Scandinavia, Australia, Ireland and many other countries in the late 1970s and into the 1980s when they were replaced with digital technology.


title: Telephone exchange

text: These systems could use the old electromechanical signaling methods inherited from crossbar and step-by-step switches. They also introduced a new form of data communications: two 1ESS exchanges could communicate with one another using a data link called Common Channel Interoffice Signaling, (CCIS). This data link was based on CCITT 6, a predecessor to SS7.


title: Telephone exchange

text: First concepts of digital switching and transmission were developed by various labs in the United States and in Europe starting in the 1930s. The first prototype digital switch was developed by Bell Labs as part of the ESSEX project while the first true digital exchange to be combined with digital transmission systems was designed by LCT (Laboratoire Central de Telecommunications) in Paris. The first digital switch to be placed into a public network in England was the Empress Exchange in London which was designed by the General Post Office research labs. It was a tandem switch that connected three Strowger exchanges. The first commercial roll-out of a fully digital local switching system was Alcatel's E10 system which began serving customers in Brittany in Northwestern France in 1972.


title: Telephone exchange

text: Digital switches encode the speech going on, in 8,000 time slices per second. (A sampling rate of 8khz). At each time slice, a digital PCM representation of the sound is made. The digital PCM signals are then sent to the receiving end of the line, where the reverse process occurs using a DAC (digital-to-analog converter), to produce the sound for the receiving phone. In other words, when someone uses a telephone, the speaker's voice is "encoded" using PCM for switching then reconstructed for the person on the other end. The speaker's voice is delayed in the process by a small fraction of one second — it is not "live", it is reconstructed — delayed only minutely.


title: Telephone exchange

text: Individual local loop telephone lines are connected to a remote concentrator. In many cases, the concentrator is co-located in the same building as the switch. The interface between remote concentrators and telephone switches has been standardised by ETSI as the V5 protocol. Concentrators are used because most telephones are idle most of the day, hence the traffic from hundreds or thousands of them may be concentrated into only tens or hundreds of shared connections.


title: Telephone exchange

text: Some telephone switches do not have concentrators directly connected to them, but rather are used to connect calls between other telephone switches. These complex machines are referred to as "carrier-level" switches or tandem switches.


title: Telephone exchange

text: Some telephone exchange buildings in small towns house only "remote" or "satellite" switches, and are homed upon a "parent" switch, usually several kilometres away. The remote switch is dependent on the parent switch for routing. Unlike a digital loop carrier, a remote switch can route calls between local phones itself, without using trunks to the parent switch.


title: Telephone exchange

text: Telephone switches are a small component of a large network. A major part, in terms of expense, maintenance, and logistics of the telephone system is outside plant, which is the wiring outside the central office. While many subscribers were served with party-lines in the middle of the 20th century, it was the goal that each subscriber telephone station were connected to an individual pair of wires from the switching system.


title: Telephone exchange

text: A typical central office may have tens of thousands of pairs of wires that appear on terminal blocks called the main distribution frame (MDF). A component of the MDF is protection: fuses or other devices that protect the switch from lightning, shorts with electric power lines, or other foreign voltages. In a typical telephone company, a large database tracks information about each subscriber pair and the status of each jumper. Before computerization of Bell System records in the 1980s, this information was handwritten in pencil in accounting ledger books.


title: Telephone exchange

text: To reduce the expense of outside plant, some companies use "pair gain" devices to provide telephone service to subscribers. These devices are used to provide service where existing copper facilities have been exhausted or by siting in a neighborhood, can reduce the length of copper pairs, enabling digital services such as Integrated Services Digital Network (ISDN) or digital subscriber line (DSL).


title: Telephone exchange

text: Pair gain or digital loop carriers (DLCs) are located outside the central office, usually in a large neighborhood distant from the CO. DLCs are often referred to as Subscriber Loop Carriers (SLCs), after a Lucent proprietary product.


title: Telephone exchange

text: DLCs can be configured as universal (UDLCs) or integrated (IDLCs). "Universal DLC"s have two terminals, a central office terminal (COT) and a remote terminal (RT), that function similarly. Both terminals interface with analog signals, convert to digital signals, and transport to the other side where the reverse is performed.


title: Telephone exchange

text: Sometimes, the transport is handled by separate equipment. In an "Integrated DLC", the COT is eliminated. Instead, the RT is connected digitally to equipment in the telephone switch. This reduces the total amount of equipment required.


title: Telephone exchange

text: Switches are used in both local central offices and in long distance centers. There are two major types in the Public switched telephone network (PSTN), the Class 4 telephone switches designed for toll or switch-to-switch connections, and the Class 5 telephone switches or subscriber switches, which manage connections from subscriber telephones. Since the 1990s, hybrid Class 4/5 switching systems that serve both functions have become common.


title: Telephone exchange

text: Another element of the telephone network is time and timing. Switching, transmission and billing equipment may be slaved to very high accuracy 10 MHz standards which synchronize time events to very close intervals. Time-standards equipment may include Rubidium- or Caesium-based standards and a Global Positioning System receiver.


title: Telephone exchange

text: Long-distance switches may use a slower, more efficient switch-allocation algorithm than local central offices, because they have near 100% utilization of their input and output channels. Central offices have more than 90% of their channel capacity unused.


title: Telephone exchange

text: Traditional telephone switches connected physical circuits (e.g., wire pairs) while modern telephone switches use a combination of space- and time-division switching. In other words, each voice channel is represented by a time slot (say 1 or 2) on a physical wire pair (A or B). In order to connect two voice channels (say A1 and B2) together, the telephone switch interchanges the information between A1 and B2. It switches both the time slot and physical connection. To do this, it exchanges data between the time slots and connections 8,000 times per second, under control of digital logic that cycles through electronic lists of the current connections. Using both types of switching makes a modern switch far smaller than either a space or time switch could be by itself.


title: Telephone exchange

text: The structure of a switch is an odd number of layers of smaller, simpler subswitches. Each layer is interconnected by a web of wires that goes from each subswitch, to a set of the next layer of subswitches. In some designs, a physical (space) switching layer alternates with a time switching layer. The layers are symmetric, because in a telephone system callers can also be called. Other designs use time-switching only, throughout the switch.


title: Telephone exchange

text: A time-division subswitch reads a complete cycle of time slots into a memory, and then writes it out in a different order, also under control of a cyclic computer memory. This causes some delay in the signal.


title: Telephone exchange

text: A space-division subswitch switches electrical paths, often using some variant of a nonblocking minimal spanning switch, or a crossover switch.


title: Telephone exchange

text: Composite switches are inherently fault-tolerant. If a subswitch fails, the controlling computer can sense the failure during a periodic test. The computer marks all the connections to the subswitch as "in use". This prevents new calls, and does not interrupt established calls. As established calls end, the subswitch becomes unused, and can be repaired. When the next test succeeds, the switch returns to full operation.


title: Telephone exchange

text: To prevent frustration with unsensed failures, all the connections between layers in the switch are allocated using first-in-first-out lists (queues). As a result, if a connection is faulty or noisy and the customer hangs up and redials, they will get a different set of connections and subswitches. A last-in-first-out (stack) allocation of connections might cause a continuing string of very frustrating failures.


title: Telephone exchange

text: A central exchange is almost always a single point of failure for local calls. As the capacity of individual switches and the optical fibre which interconnects them increases, potential disruption caused by destruction of one local office will only be magnified. Multiple fibre connections can be used to provide redundancy to voice and data connections between switching centres, but careful network design is required to avoid situations where a main fibre and its backup both go through the same damaged central office as a potential common mode failure.


title: Beta-Hydroxy beta-methylbutyric acid

text: β-Hydroxy β-methylbutyric acid (HMB), otherwise known as its conjugate base, , is a naturally produced substance in humans that is used as a dietary supplement and as an ingredient in certain medical foods that are intended to promote wound healing and provide nutritional support for people with muscle wasting due to cancer or HIV/AIDS. In healthy adults, supplementation with HMB has been shown to increase exercise-induced gains in muscle size, muscle strength, and lean body mass, reduce skeletal muscle damage from exercise, improve aerobic exercise performance, and expedite recovery from exercise. Medical reviews and meta-analyses indicate that HMB supplementation also helps to preserve or increase lean body mass and muscle strength in individuals experiencing age-related muscle loss. HMB produces these effects in part by stimulating the production of proteins and inhibiting the breakdown of proteins in muscle tissue. No adverse effects from long-term use as a dietary supplement in adults have been found.


title: Beta-Hydroxy beta-methylbutyric acid

text: HMB is sold as a dietary supplement at a cost of about per month when taking 3 grams per day. HMB is also contained in several nutritional products, including certain formulations of Ensure, Juven, and Myoplex. HMB is also present in insignificant quantities in certain foods, such as alfalfa, asparagus, avocados, cauliflower, grapefruit, and catfish.


title: Beta-Hydroxy beta-methylbutyric acid

text: The effects of HMB on human skeletal muscle were first discovered by Steven L. Nissen at Iowa State University in the . HMB has not been banned by the National Collegiate Athletic Association, World Anti-Doping Agency, or any other prominent national or international athletic organization. In 2006, only about 2% of college student athletes in the United States used HMB as a dietary supplement. As of 2017, HMB has found widespread use as an ergogenic supplement among young athletes.


title: Beta-Hydroxy beta-methylbutyric acid

text: HMB is sold as an over-the-counter dietary supplement in the free acid form, "β-hydroxy β-methylbutyric acid" (HMB-FA), and as a monohydrated calcium salt of the conjugate base, "calcium monohydrate" (HMB-Ca, CaHMB). Since only a small fraction of HMB's metabolic precursor, , is metabolized into HMB, pharmacologically active concentrations of the compound in blood plasma and muscle can only be achieved by supplementing HMB directly. A healthy adult produces approximately 0.3 grams per day, while supplemental HMB is usually taken in doses of  grams per day. HMB is sold at a cost of about per month when taken in doses of 3 grams per day. HMB is also contained in several nutritional products and medical foods marketed by Abbott Laboratories (e.g., certain formulations of Ensure, Juven, and Myoplex), and is present in insignificant quantities in certain foods, such as alfalfa, asparagus, avocados, cauliflower, grapefruit, and catfish.


title: Beta-Hydroxy beta-methylbutyric acid

text: Supplemental HMB has been used in clinical trials as a treatment for preserving lean body mass in muscle wasting conditions, particularly sarcopenia, and has been studied in clinical trials as an adjunct therapy in conjunction with resistance exercise. Based upon two medical reviews and a meta-analysis of seven randomized controlled trials, HMB supplementation can preserve or increase lean muscle mass and muscle strength in sarcopenic older adults. HMB does not appear to significantly affect fat mass in older adults. Preliminary clinical evidence suggests that HMB supplementation may also prevent muscle atrophy during bed rest. A growing body of evidence supports the efficacy of HMB in nutritional support for reducing, or even reversing, the loss of muscle mass, muscle function, and muscle strength that occurs in hypercatabolic disease states such as cancer cachexia; consequently, the authors of two 2016 reviews of the clinical evidence recommended that the prevention and treatment of sarcopenia and muscle wasting in general include supplementation with HMB, regular resistance exercise, and consumption of a high-protein diet.


title: Beta-Hydroxy beta-methylbutyric acid

text: Clinical trials that used HMB for the treatment of muscle wasting have involved the administration of 3 grams of HMB per day under different dosing regimens. According to one review, an optimal dosing regimen is to administer it in one 1 gram dose, three times a day, since this ensures elevated plasma concentrations of HMB throughout the day; however, the best dosing regimen for muscle wasting conditions is still being investigated.


title: Beta-Hydroxy beta-methylbutyric acid

text: Some branded products that contain HMB (i.e., certain formulations of Ensure and Juven) are medical foods that are intended to be used to provide nutritional support under the care of a doctor in individuals with muscle wasting due to HIV/AIDS or cancer, to promote wound healing following surgery or injury, or when otherwise recommended by a medical professional. Juven, a nutrition product which contains 3 grams of , 14 grams of -arginine, and 14 grams of -glutamine per two servings, has been shown to improve lean body mass during clinical trials in individuals with AIDS and cancer, but not rheumatoid cachexia. Further research involving the treatment of cancer cachexia with Juven over a period of several months is required to adequately determine treatment efficacy.


title: Beta-Hydroxy beta-methylbutyric acid

text: With an appropriate exercise program, dietary supplementation with 3 grams of HMB per day has been shown to increase exercise-induced gains in muscle size, muscle strength and power, and lean body mass, reduce exercise-induced skeletal muscle damage, and expedite recovery from high-intensity exercise. Based upon limited clinical research, HMB supplementation may also improve aerobic exercise performance and increase gains in aerobic fitness when combined with high-intensity interval training. These effects of HMB are more pronounced in untrained individuals and athletes who perform high intensity resistance or aerobic exercise. In resistance-trained populations, the effects of HMB on muscle strength and lean body mass are limited. HMB affects muscle size, strength, mass, power, and recovery in part by stimulating myofibrillar muscle protein synthesis and inhibiting muscle protein breakdown through various mechanisms, including the activation of mechanistic target of rapamycin complex 1 (mTORC1) and inhibition of proteasome-mediated proteolysis in skeletal muscles.


title: Beta-Hydroxy beta-methylbutyric acid

text: The efficacy of HMB supplementation for reducing skeletal muscle damage from prolonged or high-intensity exercise is affected by the time that it is used relative to exercise. The greatest reduction in skeletal muscle damage from a single bout of exercise has been shown to occur when is ingested  hours prior to exercise or is ingested  minutes prior to exercise.


title: Beta-Hydroxy beta-methylbutyric acid

text: In 2006, only about 2% of college student athletes in the United States used HMB as a dietary supplement. As of 2017, HMB has found widespread use as an ergogenic supplement among athletes. HMB has not been banned by the National Collegiate Athletic Association, World Anti-Doping Agency, or any other prominent national or international athletic organization.


title: Beta-Hydroxy beta-methylbutyric acid

text: The safety profile of HMB in adult humans is based upon evidence from clinical trials in humans and animal studies. In humans, no adverse effects in young adults or older adults have been reported when HMB is taken in doses of 3 grams per day for up to a year. Studies on young adults taking 6 grams of HMB per day for up to 2 months have also reported no adverse effects. Studies with supplemental HMB on young, growing rats and livestock have reported no adverse effects based upon clinical chemistry or observable characteristics; for humans younger than 18, there is limited data on the safety of supplemental HMB. The human equivalent dose of HMB for the no-observed-adverse-effect level (NOAEL) that was identified in a rat model is approximately 0.4 g/kg of body weight per day.


title: Beta-Hydroxy beta-methylbutyric acid

text: Two animal studies have examined the effects of HMB supplementation in pregnant pigs on the offspring and reported no adverse effects on the fetus. No clinical testing with supplemental HMB has been conducted on pregnant women, and pregnant and lactating women are advised not to take HMB by Metabolic Technologies, Inc., the company that grants licenses to include HMB in dietary supplements, due to a lack of safety studies.


title: Beta-Hydroxy beta-methylbutyric acid

text: Several components of the signaling cascade that mediates the HMB-induced increase in human skeletal muscle protein synthesis have been identified "in vivo". Similar to HMB's metabolic precursor, , HMB has been shown to increase protein synthesis in human skeletal muscle via phosphorylation of the mechanistic target of rapamycin (mTOR) and subsequent activation of , which leads to protein biosynthesis in cellular ribosomes via phosphorylation of mTORC1's immediate targets (i.e., the p70S6 kinase and the translation repressor protein 4EBP1). Supplementation with HMB in several non-human animal species has been shown to increase the serum concentration of growth hormone and insulin-like growth factor 1 (IGF-1) via an unknown mechanism, in turn promoting protein synthesis through increased mTOR phosphorylation. Based upon limited clinical evidence in humans, supplemental HMB appears to increase the secretion of growth hormone and IGF-1 in response to resistance exercise.


title: Beta-Hydroxy beta-methylbutyric acid

text: , the signaling cascade that mediates the HMB-induced reduction in muscle protein breakdown has not been identified in living humans, although it is well-established that it attenuates proteolysis in humans "in vivo". Unlike , HMB attenuates muscle protein breakdown in an insulin-independent manner in humans. HMB is believed to reduce muscle protein breakdown in humans by inhibiting the 19S and 20S subunits of the ubiquitin–proteasome system in skeletal muscle and by inhibiting apoptosis of skeletal muscle nuclei via unidentified mechanisms.


title: Beta-Hydroxy beta-methylbutyric acid

text: Based upon animal studies, HMB appears to be metabolized within skeletal muscle into cholesterol, which may then be incorporated into the muscle cell membrane, thereby enhancing membrane integrity and function. The effects of HMB on muscle protein metabolism may help stabilize muscle cell structure. One review suggested that the observed HMB-induced reduction in the plasma concentration of muscle damage biomarkers (i.e., muscle enzymes such as creatine kinase and lactate dehydrogenase) in humans following intense exercise may be due to a cholesterol-mediated improvement in muscle cell membrane function.


title: Beta-Hydroxy beta-methylbutyric acid

text: HMB has been shown to stimulate the proliferation, differentiation, and fusion of human myosatellite cells "in vitro", which potentially increases the regenerative capacity of skeletal muscle, by increasing the protein expression of certain myogenic regulatory factors (e.g., myoD and myogenin) and gene transcription factors (e.g., MEF2). HMB-induced human myosatellite cell proliferation "in vitro" is mediated through the phosphorylation of the mitogen-activated protein kinases ERK1 and ERK2. HMB-induced human myosatellite differentiation and accelerated fusion of myosatellite cells into muscle tissue "in vitro" is mediated through the phosphorylation of Akt, a serine/threonine-specific protein kinase.


title: Beta-Hydroxy beta-methylbutyric acid

text: The free acid () and monohydrated calcium salt () forms of HMB have different pharmacokinetics. HMB-FA is more readily absorbed into the bloodstream and has a longer elimination half-life (3 hours) relative to HMB-Ca (2.5 hours). Tissue uptake and utilization of HMB-FA is higher than for HMB-Ca. The fraction of an ingested dose that is excreted in urine does not differ between the two forms.


title: Beta-Hydroxy beta-methylbutyric acid

text: After ingestion, is converted to following dissociation of the calcium moiety in the gut. When the HMB-Ca dosage form is ingested, the magnitude and time at which the peak plasma concentration of HMB occurs depends on the dose and concurrent food intake. Higher HMB-Ca doses increase the rate of absorption, resulting in a peak plasma HMB level (C) that is disproportionately greater than expected of a linear dose-response relationship and which occurs sooner relative to lower doses. Consumption of HMB-Ca with sugary substances slows the rate of HMB absorption, resulting in a lower peak plasma HMB level that occurs later.


title: Beta-Hydroxy beta-methylbutyric acid

text: HMB is eliminated via the kidneys, with roughly of an ingested dose being excreted unchanged in urine. The remaining of the dose is retained in tissues or excreted as HMB metabolites. The fraction of a given dose of HMB that is excreted unchanged in urine increases with the dose.


title: Beta-Hydroxy beta-methylbutyric acid

text: The metabolism of HMB is catalyzed by an uncharacterized enzyme which converts it to (). HMB-CoA is metabolized by either enoyl-CoA hydratase or another uncharacterized enzyme, producing β-methylcrotonyl-CoA () or hydroxymethylglutaryl-CoA () respectively. is then converted by the enzyme methylcrotonyl-CoA carboxylase to methylglutaconyl-CoA (), which is subsequently converted to by methylglutaconyl-CoA hydratase. is then cleaved into and acetoacetate by lyase or used in the production of cholesterol via the mevalonate pathway.


title: Beta-Hydroxy beta-methylbutyric acid

text: In healthy individuals, approximately 60% of dietary is metabolized after several hours, with roughly 5% ( range) of dietary being converted to .<includeonly> Around 40% of dietary is converted to , which is subsequently used in the synthesis of other compounds.</includeonly>


title: Beta-Hydroxy beta-methylbutyric acid

text: The vast majority of metabolism is initially catalyzed by the branched-chain amino acid aminotransferase enzyme, producing (α-KIC). α-KIC is mostly metabolized by the mitochondrial enzyme branched-chain dehydrogenase, which converts it to isovaleryl-CoA. Isovaleryl-CoA is subsequently metabolized by isovaleryl-CoA dehydrogenase and converted to , which is used in the synthesis of acetyl-CoA and other compounds. During biotin deficiency, HMB can be synthesized from via enoyl-CoA hydratase and an unknown thioesterase enzyme, which convert into and into HMB respectively. A relatively small amount of α-KIC is metabolized in the liver by the cytosolic enzyme 4-hydroxyphenylpyruvate dioxygenase (KIC dioxygenase), which converts α-KIC to HMB. In healthy individuals, this minor pathway – which involves the conversion of to α-KIC and then HMB – is the predominant route of HMB synthesis.


title: Beta-Hydroxy beta-methylbutyric acid

text: acid is a monocarboxylic β-hydroxy acid and natural product with the molecular formula . At room temperature, pure acid occurs as a transparent, colorless to light yellow liquid which is soluble in water. acid is a weak acid with a p"K" of 4.4. Its refractive index (formula_1) is 1.42.


title: Beta-Hydroxy beta-methylbutyric acid

text: acid is a member of the carboxylic acid family of organic compounds. It is a structural analog of butyric acid with a hydroxyl functional group and a methyl substituent located on its beta carbon. By extension, other structural analogs include acid and acid.


title: Beta-Hydroxy beta-methylbutyric acid

text: A variety of synthetic routes to acid have been developed. The first reported chemical syntheses approached HMB by oxidation of alkene, vicinal diol, and alcohol precursors:


title: Beta-Hydroxy beta-methylbutyric acid

text: Depending on the experimental conditions, cycloaddition of acetone and ketene produces either or 4,4-dimethyloxetan-2-one, both of which hydrolyze under basic conditions to yield the conjugate base of HMB. The haloform reaction provides another pathway to HMB involving the exhaustive halogenation of the methyl-ketone region of diacetone alcohol with sodium hypobromite or sodium hypochlorite; Diacetone alcohol is readily available from the aldol condensation of acetone. An organometallic approach to HMB involves the carboxylation of "tert"-butyl alcohol with carbon monoxide and Fenton's reagent (hydrogen peroxide and ferrous iron). Alternatively, HMB can be prepared through microbial oxidation of acid by the fungus "Galactomyces reessii".


title: Beta-Hydroxy beta-methylbutyric acid

text: The concentration of naturally produced HMB has been measured in several human body fluids using nuclear magnetic resonance spectroscopy, liquid chromatography–mass spectrometry, and gas chromatography–mass spectrometry methods. In the blood plasma and cerebrospinal fluid (CSF) of healthy adults, the average molar concentration of HMB has been measured at 4.0 micromolar (μM). The average concentration of HMB in the intramuscular fluid of healthy men of ages has been measured at 7.0 μM. In the urine of healthy individuals of any age, the excreted urinary concentration of HMB has been measured in a range of  micromoles per millimole (μmol/mmol) of creatinine. In the breast milk of healthy lactating women, HMB and have been measured in ranges of  μg/L and  mg/L. In comparison, HMB has been detected and measured in the milk of healthy cows at a concentration of  μg/L. This concentration is far too low to be an adequate dietary source of HMB for obtaining pharmacologically active concentrations of the compound in blood plasma.


title: Beta-Hydroxy beta-methylbutyric acid

text: In a study where participants consumed 2.42 grams of pure while fasting, the average plasma HMB concentration increased from a basal level of 5.1  to 408 μM after 30 minutes. At 150 minutes post-ingestion, the average plasma HMB concentration among participants was 275 μM.


title: Beta-Hydroxy beta-methylbutyric acid

text: Abnormal HMB concentrations in urine and blood plasma have been noted in several disease states where it may serve as a diagnostic biomarker, particularly in the case of metabolic disorders. The following table lists some of these disorders along with the associated HMB concentrations detected in urine or blood plasma.


title: Beta-Hydroxy beta-methylbutyric acid

text: The first reported chemical synthesis of HMB was published in 1877 by the Russian chemists Michael and Alexander Zaytsev. HMB was isolated from the bark of "Erythrophleum couminga" (a Madagascan tree) in 1941 by Leopold Ružička. The earliest reported isolation of HMB as a human metabolite was by Tanaka and coworkers in 1968 from a patient with isovaleric acidemia.