Medium of exchange

Converting Heat to Work. There has been a historic bias in the chemical industry to think of energy use in terms of fuel and steam (qv) systems. A more fundamental approach is to minimise the input of work potential embedded in the fuel and feedstock, as well as work purchased direcdy as electricity. Steam is really just a medium of exchange, like money in an economy. 

India, Southeast Asia, the Middle East, and northern Africa centuries before it was used by ancient Greeks and Romans. In ancient times, it was used as a spice, preservative, and medicine. Pepper was such a valuable commodity that it was often used as a medium of exchange and as a form of money. Centers of commerce such as Alexandria, Constantinople (Istanbul), Calicut, and Venice arose from the trade of pepper. Arab monopolies for pepper (and other spices) kept prices high, making pepper a spice for the wealthy. To break the Arab monopolies, European powers explored for direct trade routes to India. Portugal built on Vasco da Gama s (1469-1524) trade route completed in 1488 to India to establish its own pepper monopoly in the 16th century. This in turn prompted Spain to search for western routes to India. 

The monetary aspects of gold have long dominated commercial interest in the metal. Gold through history has provided a common base from which the value of materials and services can be measured. Gold probably became a medium of exchange as early as 3400 8.C. 

Alkali metal salts, in particular sodium chloride, have been known and used since antiquity. In early times, long before the chemistry of these compounds was understood, salt was used in the preservation and flavoring of food and even as a medium of exchange. However, because of the difficulty of reducing the alkali metal ions, the elements were not isolated until comparatively recently, well after many other elements. Two of the alkali metals, sodium and potassium, are essential for human life their careful regulation is often important in treating a variety of medical conditions. 

Over the eons there have been many materials, from sea shells to spices, that have been used as a medium of exchange, but the most popular have been materials that are durable and gain as much value from their scarcity as their utility. Gold is an example of the latter, as well as gemstones, in particular, diamonds. The durability of gold, its resistance to corrosion, has contributed to its usefulness for applications such as dental prostheses and electrical contacts. Likewise, the durability of diamonds has con-... 

In the case of the estate system the consumption of the individual, his material exchange, depends on the particular division of labour to which he is subordinated. In the class system it depends only on the universal medium of exchange which he is able to acquire. In the first case, he as a socially circumscribed person takes part in exchange operations which are circumscribed by his social position. In the second case he as an owner of the universal medium of exchange is able to obtain everything that society can exchange for this token of everything. ... 

In the capitalist state, medical services are exchangediot money. In the therapeutic state, medical services are provided for diagnoses. To appreciate the significance of replacing money as a medium of exchange with diagnosis as a medium of justification, we must briefly consider the nature and function of money. 

Webster s International Dictionary devotes the better part of two pages to the various meanings of the word money and offers the following as its root meaning Something generally accepted as a medium of exchange, a measure... 

The medium of exchange used as money is called the monetary standard. Such standards are of two types, commodity standards (precious metal) and noncommodity standards (paper, or so-called fiat money ). The term fiat money comes from the Latin fiatiot let there be, as in Fiat lux ( Letthctc be light ) in the Latin bible. Fiat money is paper transformed into money by the decree of the state. 

To understand the surface magnetism of the lanthanides, one needs to understand the electronic structure. The conduction electrons are the medium of exchange interaction between adjacent 4f moments, so that electron itinerancy plays a strong role in lanthanide magnetism. Both the surface magnetic properties and the surface electronic structure of the lanthanide metals differ from that of the bulk. This review will, therefore, often include descriptions of the bulk magnetic and electronic structure so that comparisons between the bulk and the surface can be made more readily. 

The final chapter in this section focuses on that quintessential plastic object of economic exchange the credit card. Joe Deville charts the rise of the credit card, and maps the practices and campaigns whereby credit cards became more prevalent as a medium of exchange, and indeed enabled more plastic or fluid modes of credit and consumption. Deville considers the extent to which the plasticity of the credit card is a key part of its circulation, and extends this analysis to contemporary examples of debt and default. In these cases, the material presence of the credit card may become a site where the promise of credit is revoked through the demand that credit cards be cut up or returned, or it may become a site of protest, where credit card users refuse to comply... 

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