An antelope is a member of a number of even-toed ungulate species indigenous to various regions in Africa and Eurasia. Antelopes comprise a wastebasket taxon within the family Bovidae, encompassing those Old World species that are not cattle, buffalo, bison, a group of antelope is called a herd. It perhaps derives from Greek anthos and ops, perhaps meaning beautiful eye or alluding to the animals long eyelashes and this, may be a folk etymology. The word talopus and calopus, from Latin, came to be used in heraldry, in 1607, it was first used for living, cervine animals. The 91 species, most of which are native to Africa, the classification of tribes or subfamilies within Bovidae is still a matter of debate, with several alternative systems proposed. Antelope are not a cladistic or taxonomically defined group, the term is used to describe all members of the family Bovidae that do not fall under the category of sheep, cattle, or goats. Usually, all species of the Alcelaphinae, Hippotraginae, Cephalophinae, many Bovinae, the grey rhebok, and the impala are called antelopes.
No antelope species is native to Australasia or Antarctica, nor do any extant species occur in the Americas, North America is currently home to the native pronghorn, which taxonomists do not consider a member of the antelope group, but which is locally referred to as such. More species of antelope are native to Africa than to any other continent, almost exclusively in savannahs, other species occur in Asia, the Arabian Peninsula is home to the Arabian oryx and Dorcas gazelle. India is home to the nilgai, blackbuck, Tibetan antelope, and four-horned antelope, while Russia and Central Asia have the Tibetan antelope, many species of antelopes have been imported to other parts of the world, especially the United States, for exotic game hunting. With some species possessing spectacular leaping and evasive skills, individuals may escape, Texas in particular has many game ranches, as well as habitats and climates, that are very hospitable to African and Asian plains antelope species. Accordingly, wild populations of antelope and nilgai may be found in Texas.
Antelope live in a range of habitats. Numerically, most live in the African savannahs, species living in forests, woodland, or bush tend to be sedentary, but many of the plains species undertake long migrations. These enable grass-eating species to follow the rains and thereby their food supply, the gnus and gazelles of East Africa perform some of the most impressive mass migratory circuits of all mammals. For example, a male common eland can measure 178 cm at the shoulder and weigh almost 950 kg, whereas an adult royal antelope may stand only 24 cm at the shoulder and weigh a mere 1.5 kg. Not surprisingly for animals with long, slender yet powerful legs, many antelopes have long strides, some are adapted to inhabiting rock koppies and crags. Both dibatags and gerenuks habitually stand on their two legs to reach acacia and other tree foliage
Bi-metallic coins are coins consisting of two metals or alloys, generally arranged with an outer ring around a contrasting center.00 coin and all Mexican coins of $1 or higher denomination. The silver-center cent pattern produced by the United States in 1792 is another example, though not legal tender, Moores tokens were circulated widely and accepted at face value by many merchants. Despite their popularity, the Royal Mint rejected the proposal, in recent times, the first circulating bi-metallic coin was the Italian 500 lire, first issued in 1982. India introduced 10 rupee bi-metallic coins in 2009 that are dated 2006, since 1996, Canada has produced bi-metallic $2 coins, Great Britain has issued a bi-metallic 2 pounds coin since 1997 and Singapore has issued a bi-metallic 1 dollar coin since 2013. The first ever tri-metallic circulating coins were 20 franc coins introduced in France and these were similar to the corresponding bi-metallic 10 franc coins, but had two rings instead of one. As well as circulating coins, where they are restricted to high denomination coins, bi-metallic coins are often used in commemorative issues.
For example, the only coin of the United States is the $10 Library of Congress commemorative. They are used primarily as a way of securing against coin counterfeiting, the manufacturing process is similar to that of ordinary coins, except that two blanks are struck at the same time, deforming the separate blanks sufficiently to hold them together. Worldwide Bi-Metallic Collectors Club - website World bimetallic coin news - WBCN - website, new issues, country index and reference prices
Brass is a metal alloy made of copper and zinc, the proportions of zinc and copper can be varied to create a range of brasses with varying properties. It is an alloy, atoms of the two constituents may replace each other within the same crystal structure. By comparison, bronze is principally an alloy of copper and tin, however and brass may include small proportions of a range of other elements including arsenic, aluminium and silicon. The term is applied to a variety of brasses. Modern practice in museums and archaeology increasingly avoids both terms for objects in favour of the all-embracing copper alloy. It is used in zippers, Brass is often used in situations in which it is important that sparks not be struck, such as in fittings and tools used near flammable or explosive materials. Brass has higher malleability than bronze or zinc, the relatively low melting point of brass and its flow characteristics make it a relatively easy material to cast. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard, the density of brass is 8.4 to 8.73 grams per cubic centimetre.
Today, almost 90% of all alloys are recycled. Because brass is not ferromagnetic, it can be separated from ferrous scrap by passing the scrap near a powerful magnet, Brass scrap is collected and transported to the foundry where it is melted and recast into billets. Billets are heated and extruded into the form and size. The general softness of brass means that it can often be machined without the use of cutting fluid, aluminium makes brass stronger and more corrosion-resistant. Aluminium causes a highly beneficial hard layer of oxide to be formed on the surface that is thin, transparent. Tin has an effect and finds its use especially in seawater applications. Combinations of iron, aluminium and manganese make brass wear and tear resistant, to enhance the machinability of brass, lead is often added in concentrations of around 2%. Since lead has a melting point than the other constituents of the brass. The pattern the globules form on the surface of the brass increases the available surface area which in turn affects the degree of leaching.
In addition, cutting operations can smear the lead globules over the surface and these effects can lead to significant lead leaching from brasses of comparatively low lead content
António Agostinho Neto served as the 1st President of Angola, having led the Popular Movement for the Liberation of Angola in the war for independence. Until his death, he led the MPLA in the civil war, known for his literary activities, he is considered Angolas preeminent poet. His birthday is celebrated as National Heroes Day, a holiday in Angola. After secondary school he worked in the health services before going on to university. The younger Neto left Angola for Portugal, and studied medicine at the universities of Coimbra and he was arrested again in 1952 for joining the Portuguese Movement for Democratic Youth Unity. He was arrested again in 1955 and held until 1957 and he finished his studies, marrying a white 23-year-old Portuguese woman who was born in Trás-os-Montes, Maria Eugénia da Silva, the same day he graduated. He returned to Angola in 1959, was arrested again in 1960, when Angola gained their independence in 1975 he became President and held the position until his death in 1979.
The Portuguese authorities in Angola arrested Neto on 8 June 1960, at first Portugals government exiled Neto to Cape Verde. Then, once more, he was sent to jail in Lisbon, after international protests were made to Salazars administration urging Netos release, Neto was freed from prison and put under house arrest. From this he escaped, going first to Morocco and to Congo-Léopoldville, in 1962 Neto visited Washington, D. C. and asked the Kennedy administration for aid in his war against Portugal. The U. S. government turned him down, because it had oil interests in colonial Angola, Neto met Che Guevara in 1965 and began receiving support from Cuba. He visited Havana many times, and he and Fidel Castro shared similar ideological views, on 26 February 1974 his last child Mihaela Marinova was born in Bulgaria, from Bulgarian woman Radka Marinova. Following the Carnation Revolution in Portugal during April 1974, three factions vied for Angolan power. One of the three was the MPLA, to which Neto belonged, on 11 November 1975, Angola achieved full independence from the Portuguese, and Neto became the nations ruler after the MPLA seized Luanda at the expense of the other anti-colonial movements.
However, while Neto made the MPLA declare Marxism-Leninism its official doctrine, his position was to favour a socialist, as a consequence, he violently repressed a movement called Fractionism which in 1977 attempted a coup d état inspired by the Organização dos Comunistas de Angola. Tens of thousands of followers of Nito Alves were executed in the aftermath of the attempted coup, Neto died in a hospital in Moscow, while undergoing surgery for cancer, shortly before his 57th birthday. Jose Eduardo dos Santos succeeded him as president, but the Angolan civil war continued to rage for almost a quarter of a century more. Agostinho Netos poetic works were written chiefly between 1946 and 1960, largely in Portugal and he published three books of poetry during his lifetime
Copper is a chemical element with symbol Cu and atomic number 29. It is a soft and ductile metal with high thermal and electrical conductivity. A freshly exposed surface of copper has a reddish-orange color. Copper is one of the few metals that occur in nature in directly usable metallic form as opposed to needing extraction from an ore and this led to very early human use, from c.8000 BC. Copper used in buildings, usually for roofing, oxidizes to form a green verdigris, Copper is sometimes used in decorative art, both in its elemental metal form and in compounds as pigments. Copper compounds are used as agents and wood preservatives. Copper is essential to all living organisms as a trace dietary mineral because it is a key constituent of the enzyme complex cytochrome c oxidase. In molluscs and crustaceans, copper is a constituent of the blood pigment hemocyanin, replaced by the hemoglobin in fish. In humans, copper is found mainly in the liver, the adult body contains between 1.4 and 2.1 mg of copper per kilogram of body weight.
The filled d-shells in these elements contribute little to interatomic interactions, unlike metals with incomplete d-shells, metallic bonds in copper are lacking a covalent character and are relatively weak. This observation explains the low hardness and high ductility of single crystals of copper, at the macroscopic scale, introduction of extended defects to the crystal lattice, such as grain boundaries, hinders flow of the material under applied stress, thereby increasing its hardness. For this reason, copper is supplied in a fine-grained polycrystalline form. The softness of copper partly explains its high conductivity and high thermal conductivity. The maximum permissible current density of copper in open air is approximately 3. 1×106 A/m2 of cross-sectional area, Copper is one of a few metallic elements with a natural color other than gray or silver. Pure copper is orange-red and acquires a reddish tarnish when exposed to air, as with other metals, if copper is put in contact with another metal, galvanic corrosion will occur. A green layer of verdigris can often be seen on old structures, such as the roofing of many older buildings.
Copper tarnishes when exposed to sulfur compounds, with which it reacts to form various copper sulfides. There are 29 isotopes of copper, 63Cu and 65Cu are stable, with 63Cu comprising approximately 69% of naturally occurring copper, both have a spin of 3⁄2
A currency symbol is a graphic symbol used as a shorthand for a currencys name, especially in reference to amounts of money. The European Commission considers the global recognition of the euro sign € part of its success, in 2009, India launched a public competition to replace the ₨ ligature it shared with neighbouring countries. It finalised its new symbol, ₹ on 15 July 2010. It is a blend of the Latin letter R with the Devanagari letter र, when writing currency amounts the location of the symbol varies by currency. Many currencies in the English-speaking world and Latin America, place it before the amount, the Cape Verdean escudo places its symbol in the decimal separator position. The usage of many European countries, such as France, the decimal separator follows local countries standards. For instance, the United Kingdom often uses an interpunct as the point on price stickers. Commas or decimal points are common separators used in other countries, see decimal separator for information on international standards.
Older currency symbols have evolved slowly, often from previous currencies, the dollar and peso symbols originated from the mark employed to denote the Spanish real de a ocho, whereas the pound and lira symbols evolved from an L standing for libra, a Roman pound of silver. Newly invented currencies and currencies adopting new symbols have symbolism closer to their adopter, the added center bar in the real sign is meant to symbolize stability. The new Indian rupee symbol, ₹, is a combination of Latin. There are considerations, such as the perception of the business community. For a new symbol to be used, software to render it needs to be promulgated, the EU was criticized for not considering how the euro symbol would need to be customized to work in different fonts. The original design was exceptionally wide. These two factors have led to most typefaces employing customized, font-specific versions, usually with reduced width, List of currencies List of circulating currencies Currency Symbols
Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus Gossypium in the family of Malvaceae. The fiber is almost pure cellulose, under natural conditions, the cotton bolls will tend to increase the dispersal of the seeds. The plant is a native to tropical and subtropical regions around the world, including the Americas, Africa. The greatest diversity of wild species is found in Mexico, followed by Australia. Cotton was independently domesticated in the Old and New Worlds, the fiber is most often spun into yarn or thread and used to make a soft, breathable textile. Current estimates for world production are about 25 million tonnes or 110 million bales annually, China is the worlds largest producer of cotton, but most of this is used domestically. The United States has been the largest exporter for many years, in the United States, cotton is usually measured in bales, which measure approximately 0.48 cubic meters and weigh 226.8 kilograms.
Cotton cultivation in the region is dated to the Indus Valley Civilization, the Indus cotton industry was well-developed and some methods used in cotton spinning and fabrication continued to be used until the industrialization of India. Between 2000 and 1000 BC cotton became widespread across much of India, for example, it has been found at the site of Hallus in Karnataka dating from around 1000 BC. Cotton fabrics discovered in a cave near Tehuacán, Mexico have been dated to around 5800 BC, the domestication of Gossypium hirsutum in Mexico is dated between 3400 and 2300 BC. Cotton was grown upriver, made into nets, and traded with fishing villages along the coast for supplies of fish. The Spanish who came to Mexico and Peru in the early 16th century found the people growing cotton and this may be a reference to tree cotton, Gossypium arboreum, which is a native of the Indian subcontinent. According to the Columbia Encyclopedia, Cotton has been spun, woven and it clothed the people of ancient India and China.
Hundreds of years before the Christian era, cotton textiles were woven in India with matchless skill, in Iran, the history of cotton dates back to the Achaemenid era, there are few sources about the planting of cotton in pre-Islamic Iran. The planting of cotton was common in Merv and Pars of Iran, in Persian poets poems, especially Ferdowsis Shahname, there are references to cotton. Marco Polo refers to the products of Persia, including cotton. John Chardin, a French traveler of the 17th century who visited the Safavid Persia, during the Han dynasty, cotton was grown by Chinese peoples in the southern Chinese province of Yunnan. Mohamed Ali Pasha accepted the proposition and granted himself the monopoly on the sale and export of cotton in Egypt, and dictated cotton should be grown in preference to other crops
Steel is an alloy of iron and other elements, primarily carbon, that is widely used in construction and other applications because of its high tensile strength and low cost. Steels base metal is iron, which is able to take on two forms, body centered cubic and face centered cubic, depending on its temperature. It is the interaction of those allotropes with the elements, primarily carbon. In the body-centred cubic arrangement, there is an atom in the centre of each cube. Carbon, other elements, and inclusions within iron act as hardening agents that prevent the movement of dislocations that otherwise occur in the lattices of iron atoms. The carbon in steel alloys may contribute up to 2. 1% of its weight. Steels strength compared to pure iron is possible at the expense of irons ductility. With the invention of the Bessemer process in the mid-19th century and this was followed by Siemens-Martin process and Gilchrist-Thomas process that refined the quality of steel. With their introductions, mild steel replaced wrought iron, further refinements in the process, such as basic oxygen steelmaking, largely replaced earlier methods by further lowering the cost of production and increasing the quality of the product.
Today, steel is one of the most common materials in the world and it is a major component in buildings, tools, automobiles, machines and weapons. Modern steel is generally identified by various grades defined by assorted standards organizations, the noun steel originates from the Proto-Germanic adjective stakhlijan, which is related to stakhla. The carbon content of steel is between 0. 002% and 2. 1% by weight for plain iron–carbon alloys and these values vary depending on alloying elements such as manganese, nickel, tungsten, carbon and so on. Basically, steel is an alloy that does not undergo eutectic reaction. In contrast, cast iron does undergo eutectic reaction, too little carbon content leaves iron quite soft and weak. Carbon contents higher than those of steel make an alloy, commonly called pig iron, while iron alloyed with carbon is called carbon steel, alloy steel is steel to which other alloying elements have been intentionally added to modify the characteristics of steel. Common alloying elements include, nickel, molybdenum, titanium, tungsten and niobium.
Additional elements are important in steel, sulfur and traces of oxygen and copper. Alloys with a higher than 2. 1% carbon content, depending on other element content, cast iron is not malleable even when hot, but it can be formed by casting as it has a lower melting point than steel and good castability properties
United States dollar
The United States dollar is the official currency of the United States and its insular territories per the United States Constitution. It is divided into 100 smaller cent units, the circulating paper money consists of Federal Reserve Notes that are denominated in United States dollars. The U. S. dollar was originally commodity money of silver as enacted by the Coinage Act of 1792 which determined the dollar to be 371 4/16 grain pure or 416 grain standard silver, the currency most used in international transactions, it is the worlds primary reserve currency. Several countries use it as their currency, and in many others it is the de facto currency. Besides the United States, it is used as the sole currency in two British Overseas Territories in the Caribbean, the British Virgin Islands and Turks and Caicos Islands. A few countries use the Federal Reserve Notes for paper money, while the country mints its own coins, or accepts U. S. coins that can be used as payment in U. S. dollars. After Nixon shock of 1971, USD became fiat currency, Article I, Section 8 of the U. S.
Constitution provides that the Congress has the power To coin money, laws implementing this power are currently codified at 31 U. S. C. Section 5112 prescribes the forms in which the United States dollars should be issued and these coins are both designated in Section 5112 as legal tender in payment of debts. The Sacagawea dollar is one example of the copper alloy dollar, the pure silver dollar is known as the American Silver Eagle. Section 5112 provides for the minting and issuance of other coins and these other coins are more fully described in Coins of the United States dollar. The Constitution provides that a regular Statement and Account of the Receipts and that provision of the Constitution is made specific by Section 331 of Title 31 of the United States Code. The sums of money reported in the Statements are currently being expressed in U. S. dollars, the U. S. dollar may therefore be described as the unit of account of the United States. The word dollar is one of the words in the first paragraph of Section 9 of Article I of the Constitution, dollars is a reference to the Spanish milled dollar, a coin that had a monetary value of 8 Spanish units of currency, or reales.
In 1792 the U. S. Congress passed a Coinage Act, Section 20 of the act provided, That the money of account of the United States shall be expressed in dollars, or units. And that all accounts in the offices and all proceedings in the courts of the United States shall be kept and had in conformity to this regulation. In other words, this act designated the United States dollar as the unit of currency of the United States, unlike the Spanish milled dollar the U. S. dollar is based upon a decimal system of values. Both one-dollar coins and notes are produced today, although the form is significantly more common
A central bank, reserve bank, or monetary authority is an institution that manages a states currency, money supply, and interest rates. Central banks usually oversee the commercial banking system of their respective countries, Central banks in most developed nations are institutionally designed to be independent from political interference. Still, limited control by the executive and legislative bodies usually exists, prior to the 17th century most money was commodity money, typically gold or silver. However, promises to pay were widely circulated and accepted as value at least five hundred years earlier in both Europe and Asia. The Song dynasty was the first to issue generally circulating paper currency, in 1455, in an effort to control inflation, the succeeding Ming Dynasty ended the use of paper money and closed much of Chinese trade. The Bank of Amsterdam, established in the Dutch Republic in 1609, is considered to be the forerunner to modern central banks. The Wisselbanks innovations helped lay the foundations for the birth and development of the banking system that now plays a vital role in the worlds economy.
Along with a number of local banks, it performed many functions of a central banking system. Lucien Gillard calls it the European guilder, and Adam Smith devotes many pages to explaining how the bank guilder works, the model of the Wisselbank as a state bank was adapted throughout Europe, including the Bank of Sweden and the Bank of England. Established by Dutch-Latvian Johan Palmstruch in 1668, Sveriges Riksbank is often considered by many as the worlds oldest central bank, the lenders would give the government cash and issue notes against the government bonds, which could be lent again. A Royal Charter was granted on 27 July through the passage of the Tonnage Act 1694, the bank was given exclusive possession of the governments balances, and was the only limited-liability corporation allowed to issue banknotes. The £1. 2M was raised in 12 days, half of this was used to rebuild the Navy and these modern central banking functions evolved slowly through the 18th and 19th centuries. The currency crisis of 1797, caused by panicked depositors withdrawing from the Bank led to the government suspending convertibility of notes into specie payment.
The bank was accused by the bullionists of causing the exchange rate to fall from over issuing banknotes. Nevertheless, it was clear that the Bank was being treated as an organ of the state, henry Thornton, a merchant banker and monetary theorist has been described as the father of the modern central bank. An opponent of the real bills doctrine, he was a defender of the bullionist position, thorntons process of monetary expansion anticipated the theories of Knut Wicksell regarding the cumulative process which restates the Quantity Theory in a theoretically coherent form. Until the mid-nineteenth century, commercial banks were able to issue their own banknotes, many consider the origins of the central bank to lie with the passage of the Bank Charter Act of 1844. Under this law, authorisation to issue new banknotes was restricted to the Bank of England, at the same time, the Bank of England was restricted to issue new banknotes only if they were 100% backed by gold or up to £14 million in government debt
The Cuanza River, known as the Coanza, the Quanza, and the Kwanza, is a river in Angola. It empties into the Atlantic Ocean just south of the national capital Luanda, the river is navigable for about 150 miles from its mouth, located 60 kilometers south of Luanda. Its tributaries included the Cutato and Lucala, the rivers navigable lower course was the original route of Portugal invasion into northern Angola. The Capanda Dam in Malanje Province was finished in 2004, providing power to the region. The Cambambe Hydroelectric Power Station lies on the river, with the Lauca Dam under construction, the Barra do Kwanza, the mouth of the river, is gradually being developed for tourism, including a golf course. Rich biodiversity has been found in the Angolan river, according to research reported on the Science, angolas first biodiversity tally of the Kwanza River has so far found 50 fish species. Researchers from the National Fishing Research Institute and the South African Institute for Aquatic Biodiversity say genetic testing may reveal new species, angolas currency, the kwanza, is named after the river.
The river is the namesake of the provinces of Cuanza Norte, quissama National Park, to the south of the river Coanza, Encyclopædia Britannica, 9th ed. Vol. VI, New York, Charles Scribners Sons,1878, p.81. Map of the Cuanza River basin at Water Resources eAtlas