A machine is a mechanical structure that uses power to apply forces and control movement to perform an intended action. Machines can be driven by animals and people, by natural forces such as wind and water, by chemical, thermal, or electrical power, include a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement, they can include computers and sensors that monitor performance and plan movement called mechanical systems. Renaissance natural philosophers identified six simple machines which were the elementary devices that put a load into motion, calculated the ratio of output force to input force, known today as mechanical advantage. Modern machines are complex systems that consist of structural elements and control components and include interfaces for convenient use. Examples include a wide range of vehicles, such as automobiles and airplanes, appliances in the home and office, including computers, building air handling and water handling systems, as well as farm machinery, machine tools and factory automation systems and robots.
The English word machine comes through Middle French from Latin machina, which in turn derives from the Greek. The word mechanical comes from the same Greek roots. A wider meaning of "fabric, structure" is found in classical Latin, but not in Greek usage; this meaning is found in late medieval French, is adopted from the French into English in the mid-16th century. In the 17th century, the word could mean a scheme or plot, a meaning now expressed by the derived machination; the modern meaning develops out of specialized application of the term to stage engines used in theater and to military siege engines, both in the late 16th and early 17th centuries. The OED traces the formal, modern meaning to John Harris' Lexicon Technicum, which has: Machine, or Engine, in Mechanicks, is whatsoever hath Force sufficient either to raise or stop the Motion of a Body... Simple Machines are reckoned to be Six in Number, viz. the Ballance, Pulley, Wheel and Screw... Compound Machines, or Engines, are innumerable.
The word engine used as a synonym both by Harris and in language derives from Latin ingenium "ingenuity, an invention". The hand axe, made by chipping flint to form a wedge, in the hands of a human transforms force and movement of the tool into a transverse splitting forces and movement of the workpiece; the idea of a simple machine originated with the Greek philosopher Archimedes around the 3rd century BC, who studied the Archimedean simple machines: lever and screw. Archimedes discovered the principle of mechanical advantage in the lever. Greek philosophers defined the classic five simple machines and were able to calculate their mechanical advantage. Heron of Alexandria in his work Mechanics lists five mechanisms that can "set a load in motion". However, the Greeks' understanding was limited to statics and did not include dynamics or the concept of work. During the Renaissance the dynamics of the Mechanical Powers, as the simple machines were called, began to be studied from the standpoint of how much useful work they could perform, leading to the new concept of mechanical work.
In 1586 Flemish engineer Simon Stevin derived the mechanical advantage of the inclined plane, it was included with the other simple machines. The complete dynamic theory of simple machines was worked out by Italian scientist Galileo Galilei in 1600 in Le Meccaniche, he was the first to understand that simple machines do not create energy, they transform it. The classic rules of sliding friction in machines were discovered by Leonardo da Vinci, but remained unpublished in his notebooks, they were rediscovered by Guillaume Amontons and were further developed by Charles-Augustin de Coulomb. James Watt patented his parallel motion linkage in 1782, which made the double acting steam engine practical; the Boulton and Watt steam engine and designs powered steam locomotives, steam ships, factories. The Industrial Revolution was a period from 1750 to 1850 where changes in agriculture, mining and technology had a profound effect on the social and cultural conditions of the times, it began in the United Kingdom subsequently spread throughout Western Europe, North America and the rest of the world.
Starting in the part of the 18th century, there began a transition in parts of Great Britain's manual labour and draft-animal-based economy towards machine-based manufacturing. It started with the mechanisation of the textile industries, the development of iron-making techniques and the increased use of refined coal; the idea that a machine can be decomposed into simple movable elements led Archimedes to define the lever and screw as simple machines. By the time of the Renaissance this list increased to include the wheel and axle and inclined plane; the modern approach to characterizing machines focusses on the components that allow movement, known as joints. Wedge: Perhaps the first example of a device designed to manage power is the hand axe called biface and Olorgesailie. A hand axe is made by chipping stone flint, to form a bifacial edge, or wedge. A wedge is a simple machine that transforms lateral force and movement o
The Arab League, formally the League of Arab States, is a regional organization of Arab states in and around North Africa, the Horn of Africa and Arabia. It was formed in Cairo on 22 March 1945 with six members: Egypt, Transjordan, Saudi Arabia, Syria. Yemen joined as a member on 5 May 1945; the League has 22 members, but Syria's participation has been suspended since November 2011, as a consequence of government repression during the Syrian Civil War. The League's main goal is to "draw closer the relations between member States and co-ordinate collaboration between them, to safeguard their independence and sovereignty, to consider in a general way the affairs and interests of the Arab countries". Through institutions, such as the Arab League Educational and Scientific Organization and the Economic and Social Council of the Arab League's Council of Arab Economic Unity, the Arab League facilitates political, cultural and social programmes designed to promote the interests of the Arab world, it has served as a forum for the member states to coordinate their policy positions, to deliberate on matters of common concern, to settle some Arab disputes and to limit conflicts such as the 1958 Lebanon crisis.
The League has served as a platform for the drafting and conclusion of many landmark documents promoting economic integration. One example is the Joint Arab Economic Action Charter, which outlines the principles for economic activities in the region; each member state has one vote in the League Council, decisions are binding only for those states that have voted for them. The aims of the league in 1945 were to strengthen and coordinate the political, cultural and social programs of its members and to mediate disputes among them or between them and third parties. Furthermore, the signing of an agreement on Joint Defence and Economic Cooperation on 13 April 1950 committed the signatories to coordination of military defence measures. In March 2015, the Arab League General Secretary announced the establishment of a Joint Arab Force with the aim of counteracting extremism and other threats to the Arab States; the decision was reached. Participation in the project is voluntary, the army intervenes only at the request of one of the member states.
The growing militarization of the region and the increase in violent civil wars as well as terrorist movements are the reason behind the creation of the JAF, financed by the rich Gulf countries. In the early 1970s, the Economic Council of the League of Arab States put forward a proposal to create the Joint Arab Chambers of Commerce across the European states; that led, under the decree of the League of Arab States no. K1175/D52/G, to the decision by the Arab governments to set up the Arab British Chamber of Commerce, mandated to "promote and facilitate bilateral trade" between the Arab world and its major trading partner, the United Kingdom. Following adoption of the Alexandria Protocol in 1944, the Arab League was founded on 22 March 1945, it aimed to be a regional organisation of Arab states with a focus to developing the economy, resolving disputes and coordinating political aims. Other countries joined the league; each country was given one vote in the council. The first major action was the joint intervention on behalf of the majority Arab population being uprooted as the state of Israel emerged in 1948, but a major participant in this intervention, had agreed with the Israelis to divide up the Arab Palestinian state proposed by the United Nations General Assembly, Egypt intervened to prevent its rival in Amman from accomplishing its objective.
It was followed by the creation of a mutual defence treaty two years later. A common market was established in 1965; the Arab League member states cover over 13,000,000 km2 and straddles two continents: Africa and Asia. The area consists of arid deserts, such as the Sahara, it contains several fertile lands like the Nile Valley, the Jubba Valley and Shebelle Valley in the Horn of Africa, the Atlas Mountains in the Maghreb, the Fertile Crescent that stretches over Mesopotamia and the Levant. The area comprises parts of the world's longest river, the Nile; the Charter of the Arab League known as the Pact of the League of Arab States, is the founding treaty of the Arab League. Adopted in 1945, it stipulates that "the League of Arab States shall be composed of the independent Arab States that have signed this Pact."Initially, in 1945, there were only six members. Today, the Arab League has 22 members, including three African countries among the largest by area and the largest country in the Middle East.
Five countries have observer status that entitles them to express their opinion and give advice but denies them voting rights. There was a continual increase in membership during the second half of the 20th century; as of 2016, there are 22 member states: and 5 observer states: Libya was suspended on 22 February 2011, following the start of the Libyan Civil War. The National Transitional Council, the recognised interim government of Libya, sent a representative to be seated at the Arab League meeting on 17 August to participate in a discussion as to whether to readmit Libya to the organisation. Syria was suspended on 16 November 2011. On 6 March 2013, the Arab League gave the Syrian National Coalition Syria's seat in the Arab League. On 9 March 2014, secretary gener
In biology or human geography, population growth is the increase in the number of individuals in a population. Many of the world's countries, including many in Sub-Saharan Africa, the Middle East, South Asia and South East Asia, have seen a sharp rise in population since the end of the Cold War; the fear is that high population numbers are putting further strain on natural resources, food supplies, fuel supplies, housing, etc. in some of the less fortunate countries. For example, the population of Chad has grown from 6,279,921 in 1993 to 10,329,208 in 2009, further straining its resources. Vietnam, Nigeria, Egypt and the DRC are witnessing a similar growth in population. Global human population growth amounts to 1.1 % per year. The global population has grown from 1 billion in 1800 to 7.616 billion in 2018. It is expected to keep growing, estimates have put the total population at 8.6 billion by mid-2030, 9.8 billion by mid-2050 and 11.2 billion by 2100. Many nations with rapid population growth have low standards of living, whereas many nations with low rates of population growth have high standards of living.
Population began growing in the Western world early in the industrial revolution of the late 18th century. The reasons for the "Modern Rise of Population" were investigated by the British health scientist Thomas McKeown. In his publications, McKeown challenged four theories about the population growth: McKeown stated that the growth in Western population surging in the 19th century, was not so much caused by an increase in fertility, but by a decline of mortality of childhood mortality followed by infant mortality, The decline of mortality could be attributed to rising standards of living, whereby McKeown put most emphasis on improved nutritional status, His most controversial idea, at least his most disputed idea, was that he questioned the effectiveness of public health measures, including sanitary reforms and quarantine, The sometime fierce disputes that his publication provoked around the "McKeown thesis", have overshadowed his more important and unchallenged argument that curative medicine measures played little role in mortality decline, not only prior to the mid-20th century but until well into the 20th century.
Although the McKeown thesis has been disputed, recent studies have confirmed the value of his ideas. His work is pivotal for present day thinking about population growth, birth control, public health and medical care. McKeown had a major influence on many population researchers, such as health economists and Nobel prize winners Robert W. Fogel and Angus Deaton; the latter considered McKeown as "the founder of social medicine". The "population growth rate" is the rate at which the number of individuals in a population increases in a given time period, expressed as a fraction of the initial population. Population growth rate refers to the change in population over a unit time period expressed as a percentage of the number of individuals in the population at the beginning of that period; this can be written as the formula, valid for a sufficiently small time interval: P o p u l a t i o n g r o w t h r a t e = P − P P A positive growth rate indicates that the population is increasing, while a negative growth rate indicates that the population is decreasing.
A growth ratio of zero indicates that there were the same number of individuals at the beginning and end of the period—a growth rate may be zero when there are significant changes in the birth rates, death rates, immigration rates, age distribution between the two times. A related measure is the net reproduction rate. In the absence of migration, a net reproduction rate of more than 1 indicates that the population of females is increasing, while a net reproduction rate less than one indicates that the population of females is decreasing. Most populations do not grow exponentially. Once the population has reached its carrying capacity, it will stabilize and the exponential curve will level off towards the carrying capacity, when a population has depleted most its natural resources; the growth of a population can be modelled by the logistic equation d P d t = r P, where P = the population after time t. As it is a separable differential equation, the population may be solved explicitly, producing a logistic function: P ( t
Poverty is the scarcity or the lack of a certain amount of material possessions or money. Poverty is a multifaceted concept, which may include social and political elements. Absolute poverty, extreme poverty, or destitution refers to the complete lack of the means necessary to meet basic personal needs such as food and shelter; the threshold at which absolute poverty is defined is considered to be about the same, independent of the person's permanent location or era. On the other hand, relative poverty occurs when a person who lives in a given country does not enjoy a certain minimum level of "living standards" as compared to the rest of the population of that country. Therefore, the threshold at which relative poverty is defined varies from country to another, or from one society to another. Providing basic needs can be restricted by constraints on government's ability to deliver services, such as corruption, tax avoidance and loan conditionalities and by the brain drain of health care and educational professionals.
Strategies of increasing income to make basic needs more affordable include welfare, economic freedoms and providing financial services. Poverty reduction is still a major issue for many international organizations such as the United Nations, the World Bank, United States Agency for International Development, Oxfam, CARE, World Vision International, the Bill and Melinda Gates Foundation, the Red Cross among a plethora of others. In 2012 it was estimated that, using a poverty line of $1.25 a day, 1.2 billion people lived in poverty. Given the current economic model, built on GDP, it would take 100 years to bring the world's poorest up to the poverty line of $1.25 a day. UNICEF estimates; the World Bank forecasted in 2015 that 702.1 million people were living in extreme poverty, down from 1.75 billion in 1990. Extreme poverty is observed in all parts including developed economies. Of the 2015 population, about 347.1 million people lived in Sub-Saharan Africa and 231.3 million lived in South Asia.
According to the World Bank, between 1990 and 2015, the percentage of the world's population living in extreme poverty fell from 37.1% to 9.6%, falling below 10% for the first time. The People's Republic of China accounts for over three quarters of global poverty reduction from 1990 to 2005. Though, as noted, China accounted for nearly half of all extreme poverty in 1990. In public opinion around the world people surveyed tend to incorrectly think extreme poverty hasn't decreased. During the 2013 to 2015 period The World Bank reported that extreme poverty fell from 11% to 10%, however they noted that the rate of decline had slowed by nearly half from the 25 year average with parts of sub-saharan Africa returning to early 2000 levels; the World Bank attributed this to increasing violence following the Arab Spring, population increases in Sub-Saharan Africa, general African inflationary pressures and economic malaise were the primary drivers for this slow down. There is disagreement among experts as to what would be considered a realistic poverty rate with one considering it "an inaccurately measured and arbitrary cut off".
Some contend that a higher poverty line is needed, such as a minimum of $7.40 or $10 to $15 a day. They argue that these levels would better reflect the cost of basic needs and normal life expectancy. One estimate places the true scale of poverty much higher than the World Bank, with an estimated 4.3 billion people living with less than $5 a day and unable to meet basic needs adequately. It has been argued by some academics that the neoliberal policies promoted by global financial institutions such as the IMF and the World Bank are exacerbating both inequality and poverty. Poverty is the lack of a certain amount of material possessions or money; the word poverty comes from Latin paupertās from pauper. There are several definitions of poverty depending on the context of the situation it is placed in, the views of the person giving the definition. Income Poverty: a family's income fails to meet a federally established threshold that differs across countries. United Nations: Fundamentally, poverty is the inability of having choices and opportunities, a violation of human dignity.
It means lack of basic capacity to participate in society. It means not having enough to feed and clothe a family, not having a school or clinic to go to, not having the land on which to grow one's food or a job to earn one's living, not having access to credit, it means insecurity and exclusion of individuals and communities. It means susceptibility to violence, it implies living in marginal or fragile environments, without access to clean water or sanitation. World Bank: Poverty is pronounced deprivation in well-being, comprises many dimensions, it includes low incomes and the inability to acquire the basic goods and services necessary for survival with dignity. Poverty encompasses low levels of health and education, poor access to clean water and sanitation, inadequate physical security, lack of voice, insufficient capacity and opportunity to better one's life. Poverty is measured as either absolute or relative. In the United Kingdom, the second Cameron ministry came under attack for their redefinition of poverty.
Considering that two-thirds of people who found work were accepting wages that are below the living wage t
Unemployment or joblessness is a situation in which able-bodied people who are looking for a job cannot find a job. The causes of unemployment are debated. Classical economics, new classical economics, the Austrian School of economics argued that market mechanisms are reliable means of resolving unemployment; these theories argue against interventions imposed on the labor market from the outside, such as unionization, bureaucratic work rules, minimum wage laws and other regulations that they claim discourage the hiring of workers. Keynesian economics emphasizes the cyclical nature of unemployment and recommends government interventions in the economy that it claims will reduce unemployment during recessions; this theory focuses on recurrent shocks that reduce aggregate demand for goods and services and thus reduce demand for workers. Keynesian models recommend government interventions designed to increase demand for workers, its namesake economist John Maynard Keynes, believed that the root cause of unemployment is the desire of investors to receive more money rather than produce more products, not possible without public bodies producing new money.
A third group of theories emphasize the need for a stable supply of capital and investment to maintain full employment. On this view, government should guarantee full employment through fiscal policy, monetary policy and trade policy as stated, for example, in the US Employment Act of 1946, by counteracting private sector or trade investment volatility, reducing inequality. In addition to theories of unemployment, there are a few categorizations of unemployment that are used to more model the effects of unemployment within the economic system; some of the main types of unemployment include structural unemployment and frictional unemployment, as well as cyclical unemployment, involuntary unemployment, classical unemployment. Structural unemployment focuses on foundational problems in the economy and inefficiencies inherent in labor markets, including a mismatch between the supply and demand of laborers with necessary skill sets. Structural arguments emphasize causes and solutions related to disruptive technologies and globalization.
Discussions of frictional unemployment focus on voluntary decisions to work based on each individuals' valuation of their own work and how that compares to current wage rates plus the time and effort required to find a job. Causes and solutions for frictional unemployment address job entry threshold and wage rates; the unemployment rate is a measure of the prevalence of unemployment and it is calculated as a percentage by dividing the number of unemployed individuals by all individuals in the labor force. During periods of recession, an economy experiences a high unemployment rate. Millions of people globally or 6% of the world's workforce were without a job in 2012; the state of being without any work yet looking for work is called unemployment. Economists distinguish between various overlapping types of and theories of unemployment, including cyclical or Keynesian unemployment, frictional unemployment, structural unemployment and classical unemployment; some additional types of unemployment that are mentioned are seasonal unemployment, hardcore unemployment, hidden unemployment.
Though there have been several definitions of "voluntary" and "involuntary unemployment" in the economics literature, a simple distinction is applied. Voluntary unemployment is attributed to the individual's decisions, whereas involuntary unemployment exists because of the socio-economic environment in which individuals operate. In these terms, much or most of frictional unemployment is voluntary, since it reflects individual search behavior. Voluntary unemployment includes workers who reject low wage jobs whereas involuntary unemployment includes workers fired due to an economic crisis, industrial decline, company bankruptcy, or organizational restructuring. On the other hand, cyclical unemployment, structural unemployment, classical unemployment are involuntary in nature. However, the existence of structural unemployment may reflect choices made by the unemployed in the past, while classical unemployment may result from the legislative and economic choices made by labour unions or political parties.
The clearest cases of involuntary unemployment are those where there are fewer job vacancies than unemployed workers when wages are allowed to adjust, so that if all vacancies were to be filled, some unemployed workers would still remain. This happens with cyclical unemployment, as macroeconomic forces cause microeconomic unemployment which can boomerang back and exacerbate these macroeconomic forces. Classical, or real-wage unemployment, occurs when real wages for a job are set above the market-clearing level causing the number of job-seekers to exceed the number of vacancies. On the other hand, most economists argue that as wages fall below a livable wage many choose to drop out of the labor market and no longer seek employment; this is true in countries where low-income families are supported through public welfare systems. In such cases, wages would have to be high enough to motivate people to choose employment over what they receive through public welfare. Wages below a livable wage are to result in lower labor market participation in the above-stated scenario.
In addition, consumption of goods and services is the primary driver of increased demand for labor. Higher wages lead to workers having more income available to consume services. Therefore, higher wages increase gene
Salt is a mineral composed of sodium chloride, a chemical compound belonging to the larger class of salts. Salt is present in vast quantities in seawater; the open ocean has about 35 grams of solids per liter of sea water, a salinity of 3.5%. Salt is essential for life in general, saltiness is one of the basic human tastes. Salt is one of the oldest and most ubiquitous food seasonings, salting is an important method of food preservation; some of the earliest evidence of salt processing dates to around 6,000 BC, when people living in the area of present-day Romania boiled spring water to extract salts. Salt was prized by the ancient Hebrews, the Greeks, the Romans, the Byzantines, the Hittites and the Indians. Salt became an important article of trade and was transported by boat across the Mediterranean Sea, along specially built salt roads, across the Sahara on camel caravans; the scarcity and universal need for salt have led nations to go to war over it and use it to raise tax revenues. Salt has other cultural and traditional significance.
Salt is processed from salt mines, by the evaporation of seawater and mineral-rich spring water in shallow pools. Its major industrial products are caustic chlorine. Of the annual global production of around two hundred million tonnes of salt, about 6% is used for human consumption. Other uses include water conditioning processes, de-icing highways, agricultural use. Edible salt is sold in forms such as sea salt and table salt which contains an anti-caking agent and may be iodised to prevent iodine deficiency; as well as its use in cooking and at the table, salt is present in many processed foods. Sodium is an essential nutrient for human health via its role as an osmotic solute. Excessive salt consumption may increase the risk of cardiovascular diseases, such as hypertension, in children and adults; such health effects of salt have long been studied. Accordingly, numerous world health associations and experts in developed countries recommend reducing consumption of popular salty foods; the World Health Organization recommends that adults should consume less than 2,000 mg of sodium, equivalent to 5 grams of salt per day.
All through history, the availability of salt has been pivotal to civilization. What is now thought to have been the first city in Europe is Solnitsata, in Bulgaria, a salt mine, providing the area now known as the Balkans with salt since 5400 BC; the name Solnitsata means "salt works". While people have used canning and artificial refrigeration to preserve food for the last hundred years or so, salt has been the best-known food preservative for meat, for many thousands of years. A ancient salt-works operation has been discovered at the Poiana Slatinei archaeological site next to a salt spring in Lunca, Neamț County, Romania. Evidence indicates that Neolithic people of the Precucuteni Culture were boiling the salt-laden spring water through the process of briquetage to extract the salt as far back as 6050 BC; the salt extracted from this operation may have had a direct correlation to the rapid growth of this society's population soon after its initial production began. The harvest of salt from the surface of Xiechi Lake near Yuncheng in Shanxi, dates back to at least 6000 BC, making it one of the oldest verifiable saltworks.
There is more salt in animal tissues, such as meat and milk, than in plant tissues. Nomads who subsist on their flocks and herds do not eat salt with their food, but agriculturalists, feeding on cereals and vegetable matter, need to supplement their diet with salt. With the spread of civilization, salt became one of the world's main trading commodities, it was of high value to the ancient Hebrews, the Greeks, the Romans, the Byzantines, the Hittites and other peoples of antiquity. In the Middle East, salt was used to ceremonially seal an agreement, the ancient Hebrews made a "covenant of salt" with God and sprinkled salt on their offerings to show their trust in him. An ancient practice in time of war was salting the earth: scattering salt around in a defeated city to prevent plant growth; the Bible tells the story of King Abimelech, ordered by God to do this at Shechem, various texts claim that the Roman general Scipio Aemilianus Africanus ploughed over and sowed the city of Carthage with salt after it was defeated in the Third Punic War.
Salt may have been used for barter in connection with the obsidian trade in Anatolia in the Neolithic Era. Salt was included among funeral offerings found in ancient Egyptian tombs from the third millennium BC, as were salted birds, salt fish. From about 2800 BC, the Egyptians began exporting salt fish to the Phoenicians in return for Lebanon cedar and the dye Tyrian purple. Herodotus described salt trading routes across Libya back in the 5th century BC. In the early years of the Roman Empire, roads were built for the transportation of salt from the salt imported at Ostia to the capital. In Africa, salt was used as currency south of the Sahara, slabs of rock salt were used as coins in Abyssinia. Moorish merchants in the 6th century traded salt for weight for weight; the Tuareg have traditionally maintained routes across the Sahara for the transportation of salt by Azalai. The caravans