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Egyptian Pyramids
1. There have been many different styles or kinds of architecture in the past and there are many different styles today in different parts of the world. The oldest monuments which are met within architecture are the colossal pyramids of Egypt most of which were constructed about 6,000 years ago.
2. The pyramids are large triangular buildings which were placed over the tombs of Egyptian kings. The best known of the pyramids are a group of three built at Giza south of Cairo. The largest of these is 482 feet high. They tell us of the advanced civilization of ancient Egypt which is much spoken about even in our days. It was a country which had expert mathematicians and engineers where astronomy and philosophy were known and studied. The country was rich in hard and durable stone, but poor in timber and metal, so the main material used for construction was granite, and this was the reason for the durability of the pyramids.
3. Large blocks of stone were transported over long distances by land and water, and placed into position with the help of the most primitive equipment. That was done by slaves working for thirty or forty years. All this great amount of work was done, masses of material and a large territory sometimes of about 52,000 square meters were used, only for protecting the body of a dead king and constructing a dwelling place for his happy life in the «other world».
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Checks and Balances
1. The U.S. Constitution establishes three branches for the federal government: executive, legislative, and judicial. The three branches work together to help the country. Each branch has its own responsibilities and powers. No branch has more power than the other branches. They have balanced powers. Each branch has separate duties to check the powers of the other branches.
2. When a new state – the USA – was born, the Founders of the state thought that if there was no balance of power among different branches of government it would lead to tyranny. The problem was how to create a system of government with balanced powers. That’s why James Madison (1751 – 1836) favored the constitution that limited government by means of a) separation of powers; b) a system of checks and balances, where checks – limitation of the duties of each branch, and balances – separate powers to each branch.
3. Congress has the power to make laws, but the President may veto any act of Congress. Congress, in its turn, can pass a law over a veto by a two-thirds vote in each house. Congress can also refuse to provide funds requested by the President. The President can appoint important officials of his administration, but they must be approved by the Senate. The President also has the power to name all federal judges: they, too, must be approved by the Senate.
4. The system of checks and balances makes compromise and consensus necessary. This system protects against extremes. It means, for example, that new presidents cannot radically change governmental policies just as they wish.
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Early Christian and Byzantine Architecture
1. The architecture of Byzantium, or Eastern Roman Empire, was the culmination of Early Christian architecture. This style can be traced back to the period after 330 BC. The art characteristic of the developed Byzantine Empire had enormous influence on both East and West, spread widely and lasted throughout the Middle Ages until the fall of Constantinople to the Turks in 1453.
2. The dominant Byzantine art was architecture. It was characterized by round arches, elaborate columns, richness in decorative elements and colour. But the chief contribution of the Byzantine style to the architecture of the world was large pendentive-supported dome. Brick was the main material used for the construction of Byzantine churches. It was covered externally with plaster and internally with thin marble facing and mosaics above.
3. The Byzantine style reached a high point in the reign of the Emperor Justinian (527-565). He built and rebuilt 26 churches, many hospitals, bridges aqueducts, and fortress. The outstanding masterpiece of Byzantine church architecture is Hagia or Saint Sophia in Constantinople (now Istanbul). Hagia Sophia remained unique and no attempts were thereafter made by Byzantine Builders to emulate it. Its chief feature is the huge dome, approximately 32.6 m in diameter, rising 56 m above the floor. It’s carried on pendentives. There are also half-domes at two ends which are, in turn, carried by smaller semidomed exedrae. The interior surface of the edifice is richly decorated.
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THE AMERICAN ECONOMY AT THE END OF THE 20TH CENTURY
1. The United States entered the 21st century with an economy that was bigger, and by many measures more successful, than ever. Not only had it endured two world wars and a global depression in the first half of the 20th century, but it had surmounted challenges ranging from a 40-year Cold War with the Soviet Union to extended bouts of sharp inflation, high unemployment, and enormous government budget deficits in the second half of the century. The nation finally enjoyed a period of economic calm in the 1990s: prices were stable, unemployment dropped to its lowest level in almost 30 years, the government posted a budget surplus, and the stock market experienced an unprecedented boom. In 1998, America’s gross domestic product exceeded $8.5 trillion.
2. Though the United States held less than 5 percent of the world’s population, it accounted for more than 25 percent of the world’s economic output. Japan, the world’s second largest economy, produced about half as much. And while Japan and many of the world’s other economies grappled with slow growth and other problems in the 1990s, the American economy recorded the longest uninterrupted period of expansion in its history.
3. As in earlier periods, however, the United States had been undergoing profound economic change at the beginning of the 21st century. A wave of technological innovations in computing, telecommunications, and the biological sciences were profoundly affecting how Americans work and play.
4. The United States remains a “market economy.” Americans continue to believe that an economy generally operates best when decisions about what to produce and what prices to charge for goods are made through the give-and-take of millions of independent buyers and sellers, not by government or by powerful private interests. In a free market system, Americans believe, prices are most likely to reflect the true value of things, and thus can best guide the economy to produce what is most needed.
‘Continuity and Change’ http://usinfo.state.gov
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Geography
1. Geography as a discipline can be split broadly into two main subfields: human geography and physical geography. The former focuses largely on the built environment and how space is created, viewed and managed by humans as well as the influence humans have on the space they occupy. The latter examines the natural environment and how the climate, vegetation and life, soil, water and landforms are produced and interact. As a result of the two subfields using different approaches a third field has emerged, which is environmental geography.
2. Geographers attempt to understand the earth in terms of physical and spatial relationships. The first geographers focused on the science of mapmaking and finding ways to precisely project the surface of the earth. In this sense, geography bridges some gaps between the natural sciences and social sciences. Historical geography is often taught in a college in a unified Department of Geography.
3. Modern geography is an all-encompassing discipline, closely related to GISc, that seeks to understand humanity and its natural environment. Practitioners of geography use many technologies and methods to collect data such as GIS, remote sensing, aerial photography, statistics, and global positioning systems (GPS).
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Historical Archaeology
1. Archaeology has long been an accepted tool for studying prehistoric cultures. Relatively recently the same techniques have been systematically applied to studies of the more immediate past. This has been called «historical archaeology», a term that is used in the United States to refer to any archaeological investigation into North American sites that postdate the arrival of Europeans.
2. Back in the 1930's and 1940's, when building restoration was popular, historical archaeology was primarily a tool of architectural reconstruction. The role of archaeologists was to find the foundations of historic buildings and then take a back seat to architects. The mania for reconstruction had largely subsided by the 1950's and 1960's. Most people entering historical archaeology during this period came out of university anthropology departments, where they had studied prehistoric cultures.
3. They were, by training, social scientists, not historians, and their work tended to reflect this bias. The questions they framed and the techniques they used were designed to help them understand, as scientists, how people behaved. But because they were treading on historical ground for which there was often extensive written documentation, and because their own knowledge of these periods was usually limited, their contributions to American history remained circumscribed. Their reports, highly technical and sometimes poorly written, went unread.
4. More recently, professional archaeologists have taken over. These researchers have sought to demonstrate that their work can be a valuable tool not only of science but also of history, providing fresh insights into the daily lives of ordinary people whose existences might not otherwise be so well documented. This newer emphasis on archaeology as social history has shown great promise, and indeed work done in this area has lead to a reinterpretation of the United States past.
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Agroforestry
1. Agroforestry is an integrated approach of using the interactive benefits from combining trees and shrubs with crops and/or livestock. It combines agricultural and forestry technologies to create more diverse, productive, profitable, healthy land-use systems.
2. In agroforestry systems, trees or shrubs are intentionally used within agricultural systems, or non-timber forest products are cultured in forest settings. Knowledge, careful selection of species and good management of trees and crops are needed to optimize the production and positive effects within the system and to minimize negative competitive effects.
3. Agroforestry systems can be advantageous over conventional agricultural and forest production methods through increased productivity, economic benefits, social outcomes and the ecological goods and services provided. Biodiversity in agroforestry systems is typically higher than in conventional agricultural systems. Agroforestry incorporates at least several plant species into a given land area and creates a more complex habitat that can support a wider variety of birds, insects, and other animals. Agroforestry also has the potential to help reduce climate change since trees take up and store carbon at a faster rate than crop.
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Fiber-optic communication
1. In fiber-optic communications information is transmitted by sending light through optical fibers. The light forms an electromagnetic carrier wave that is modulated to carry information. First developed in the 1970s, fiber-optic communication systems have revolutionized the telecommunications industry and have played a major role in the advent of the Information Age.
2. Optical fiber is used by many telecommunications companies to transmit telephone signals, Internet communication, and cable television signals. Due to much lower attenuation and interference, optical fiber has large advantages over existing copper wire in long-distance and high-demand applications. However, infrastructure development within cities was relatively difficult and time-consuming, and fiber-optic systems were complex and expensive to install and operate.
3. Due to these difficulties, fiber-optic communication systems have primarily been installed in long-distance applications, where they can be used to their full transmission capacity, offsetting the increased cost. Since 2000, the prices for fiber-optic communications have dropped considerably.
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Interpol
1. Interpol is an intergovernmental body established to promote mutual cooperation between police authorities around the world and to develop means of effectively preventing crime. Founded in Vienna in 1923 and reconstituted in 1946, Interpol is strictly nonpolitical and is forbidden to undertake any activities of a religious, racial, or military nature. The majority of countries belong to Interpol, and only government-approved police bodies may hold membership. Among the first to fight international terrorism and hijackings, Interpol leads the war on narcotics, assists a number of nations in the continuing search for wanted Nazi war criminals. Interpol like any other police force is to safeguard the basic rights of every citizen.
2. The main bodies of Interpol are the general assembly, the executive committee, the general secretariat. The general assembly is composed of the delegates from each member country. It is “the Supreme Authority”. The general assembly meets annually to decide policy and to elect the executive committee, consisting of a president, three vice presidents, and nine delegates, all of different nationalities. The general secretariat, based in Lyons, France, is the permanent administrative headquarters. It contains a number of departments four of which specialize in certain crimes: one handles murder, burglary, assault, larceny, car theft, and missing persons; another deals with bank frauds and other types of embezzlement; a third with drug traffic and moral offences; and a fourth deals with forgery and counterfeiting. The general secretariat coordinates the international activities of member countries, holds a library of international criminal records, and organizes regular meetings at which delegates can exchange information on police work. Interpol is financed by contributions from member countries.
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LES EVOLUTIONS POSSIBLES DE LA ROBOTIQUE
1. La microrobotique est un champ d'étude en plein essor. La compréhension des phénomènes physiques dans la manipulation à l'échelle du micromètre et la miniaturisation des mécanismes sont d'un intérêt crucial pour la micro-ingénierie. Les recherches concernent aussi bien les capteurs, que les actionneurs et les préhenseurs.
2. De nombreux roboticiens se concentrent aujourd'hui sur la locomotion humaine et animale. C'est une problématique difficile, en partie à cause de la puissance de calcul nécessaire. L'étude des robots à pattes a été menée depuis plusieurs décennies, surtout sur les robots hexapodes, quadripèdes, etc. La tendance était alors de copier la flexibilité, la robustesse et l'adaptabilité des insectes. Ce type de robot est statiquement stable, et donc plus facile à contrôler.
3. Aujourd'hui on assiste à une intensification de la recherche sur la locomotion bipède, qui est par nature dynamiquement stable, donc plus difficile à maîtriser. Mais les avantages sont considérables: progression dans la connaissance de la bipédie, meilleur franchissement d'obstacle et adaptation à l'environnement humain. Ainsi de nombreuses universités et entreprises, surtout japonaises, se sont lancées dans la construction de robots humanoïdes.
4. La robotique médicale est également très active. De nouveaux robots sont développés pour la chirurgie mini-invasive et la téléchirurgie. De nouvelles techniques sont exploitées, comme les actionneurs AMS (alliages à mémoire de forme), la microrobotique et les interfaces haptiques. Des algorithmes d'analyse d'images sont développés dans la même voie. La recherche s'est aussi orientée vers la navigation, la localisation et la planification de trajectoire. L'exploration sous-marine et spatiale sont des domaines où la robotique est d'une grande utilité. Les développements futurs concernent aussi la vision robotique, notamment dans le but de concevoir des véhicules «intelligents», ou des robots de surveillance et d'exploration.
http://fr.wikipedia.org/
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A microwave oven
1. A microwave oven works by passing non-ionizing microwave radiation, usually at a frequency of 2.45 gigahertz (a wavelength of 12.24 centimetres), through the food. Microwave radiation is between common radio and infrared frequencies. Water, fat, and other substances in the food absorb energy from the microwaves in a process called dielectric heating.
2. Many molecules (such as those of water) are electric dipoles, meaning that they have a positive charge at one end and a negative charge at the other, and therefore rotate as they try to align themselves with the alternating electromagnetic field of the microwaves. This molecular movement represents heat which is then dispersed as the rotating molecules hit other molecules and put them into motion.
3. Microwave heating is more efficient on liquid water than on fats and sugars (which have a smaller molecular dipole moment), and also more efficient than on frozen water (where the molecules are not free to rotate). Microwave heating is sometimes explained as a resonance of water molecules, but this is incorrect: such resonance only occurs in water vapor at much higher frequencies, at about 20 GHz.
4. A common misconception is that microwave ovens cook food from the "inside out". In reality, microwaves are absorbed in the outer layers of food in a manner somewhat similar to heat from other methods. The misconception arises because microwaves penetrate dry non-conductive substances at the surfaces of many common foods, and thus often induce initial heat more deeply than other methods. Depending on water content, the depth of initial heat deposition may be several centimetres or more with microwave ovens, in contrast to infrared or convection heating, which deposit heat thinly at the food surface. Penetration depth of microwaves is dependent on food composition and the frequency, with lower microwave frequencies (longer wavelengths) penetrating better.
(Encyclopedia Wikipedia)
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Channels of Marketing
1. Individual consumers and corporate buyers are aware that thousands of goods and services are available through a very large number of diverse channel outlets. What they may not be well aware of is the fact that the channel structure, or the set of institutions, agencies, and establishments through which the product must move to get to them, can be amazingly complex.
2. Usually, institutions specializing in manufacturing, wholesaling, retailing, and many other areas join forces in marketing channel arrangements to make possible the delivery of goods to industrial users or customers and to final consumers. The same is true for the marketing of services. For example, in the case of health care delivery, hospitals, laboratories, insurance companies, and drugstores combine efforts in an organized channel arrangement to ensure the delivery of a critical service.
3. Therefore, marketing channels can be viewed as sets of interdependent organizations involved in the process of making a product or service available for use or consumption. Not only do marketing channels satisfy demand by supplying goods and services at the right place, quantity, quality, and price, but they also stimulate demand through the promotional activities of the units (e.g., retailers, manufacturers' representatives, sales offices, and wholesalers) comprising them.
4. The major focus of marketing channel management is on delivery. Producers of goods (including manufacturers of industrial and consumer goods, legislators, educational administrators and insurance companies) are individually capable of generating only form or structural utility for their «products».
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General objectives of teaching
1. The classification of the general objectives of teaching in terms of school subject matter is not sufficient to explain the ultimate ends of education. These include, essentially, the promotion of a well-integrated person capable of taking a responsible, active role in society. With such a purpose in mind, one may achieve more insight by choosing a psychological analysis of the objectives into the attainment of intellectual abilities and social insights (cognition), the learning of practical active skills (psychomotor learning), and the development of emotions, attitudes, and values (affective learning).
2. Cognitive growth begins at the level of the infant school, with the acquisition of early language and numerical capabilities, and continues increasingly to dominate education to the secondary and higher levels. But the learner is more than an enlarging reservoir of information. With this acquisition goes a growing power to generalize, abstract, infer, interpret, explain, apply, and create. Cognitive training produces a thinker–observer aware of the modes of thought and judgment making up human intellectual activity. In the final stages, the teacher aims at a thinker, critic, organizer, and creator.
3. The permeation of emotional learning throughout the whole educative process is not always obvious, in part because very often it is brought about incidentally. Teachers may be self-conscious and self-critical about the deliberate inculcation of emotional responses, which will provide the energy and a mainspring of social life.
4. The acquisition and application of values and attitudes are most marked by the time of adolescence and dominate the general life of the young individual. Theoretical, aesthetic, social, economic, political, hedonistic, and religious values pervade the school curriculum. Literature, art, the humanities, and religious teaching are all directly involved, and the teaching of science and mathematics can bring about a positive attitude toward cognitive and theoretical values.
(Encyclopedia Britannica)
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JACQUES CHIRAC
1. Premier président gaulliste depuis vingt et un ans, Jacques Chirac a mené une campagne annonçant de grandes réformes. Pourtant, rapidement, Jacques Chirac et son Premier ministre Alain Juppé vont affronter des difficultés économiques et financières qui les conduisent à infléchir leur politique dans le sens de la rigueur budgétaire (hausse des impôts, réduction des déficits), ce qui suscite un mouvement social important pendant l'hiver 1995–1996.
2. Le président et le gouvernement en subissent les conséquences en termes de popularité. Très actif en politique étrangère, Jacques Chirac connaît certains succès, comme en Bosnie-Herzégovine, mais il rencontre une forte opposition lors de la reprise temporaire des essais nucléaires français (1995). Il entreprend également une profonde refonte de la défense nationale, avec notamment la fin de la conscription. En revanche, la rigidité du gouvernement face aux revendications de la Corse accentue la violence et le sentiment d'un problème politique non réglé.
3. Les deux premières années de ce septennat sont marquées par une volonté de réforme de l'Etat, des tentatives de modification du système français de production, qui suscitent des réactions de défense, une volonté de simplifier la fiscalité et une accélération des processus de privatisations. Ces mesures s'inscrivent, sur le plan économique, dans la perspective de l'Union économique et monétaire et de la convergence des finances publiques.
4. L'insatisfaction de la population amène la victoire de la gauche aux élections législatives anticipées de 1997 et la formation d'un gouvernement de cohabitation dirigé par Lionel Jospin. Lors des élections régionales de mars 1998, la gauche plurielle devance en pourcentage de voix (34,5 %) la coalition RPR-UDF (32,5 %); le Front national remportant un peu plus de 15 % des voix.
Economie et science
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FIRST PERSONAL COMPUTERS
1. Personal computer is a computer designed for use by only one person at a time. It is a type of microcomputer - i.e., a small digital computer that uses only one microprocessor. A typical personal computer assemblage consists of a central processing unit, primary, or internal, memory, consisting of hard magnetic disks and a disk drive; various input/output devices, including a display screen, keyboard and mouse, modem, and printer; and secondary, or external, memory, usually in the form of floppy disks or CDs.
2. Computers small and inexpensive enough to be purchased by individuals for use in their homes first became feasible in the 1970s, when large-scale integration made it possible to construct a sufficiently powerful microprocessor on a single semiconductor chip. A small firm named MITS made the first personal computer, the Altair. This computer, which used the Intel Corporation's 8080 microprocessor, was developed in 1974. Though the Altair was popular among computer hobbyists, its commercial appeal was limited, since purchasers had to assemble the machine from a kit.
3. The personal computer industry truly began in 1977, when Apple Computer, Inc. introduced the Apple II, one of the first pre-assembled, mass-produced personal computers. Radio Shack and Commodore Business Machines also introduced personal computers that year. These machines used 8-bit microprocessors and possessed rather limited memory capacity. But because personal computers were much less expensive than mainframes, they could be purchased by individuals, small and medium-sized businesses, and primary and secondary schools.
4. The IBM Corporation, the world's dominant computer maker, did not enter the new market until 1981, when it introduced the IBM Personal Computer, or IBM PC which was only slightly faster than rival machines, but it had about 10 times their memory capacity, and it was backed by IBM's large sales organization.
(Encyclopedia Britannica)
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International Telecommunication Union
1. The International Telecommunication Union, originally founded as the International Telegraph Union, is a specialized agency of the United Nations which is responsible for information and communication technologies. The International Telecommunication Union coordinates the shared global use of the radio spectrum, promotes international cooperation in assigning satellite orbits, works to improve telecommunication infrastructure in the developing world, and assists in the development and coordination of worldwide technical standards.
2. The International Telecommunication Union also organizes worldwide and regional exhibitions and forums, such as ITU TELECOM WORLD, bringing together representatives of government and the telecommunications and ICT industry to exchange ideas, knowledge and technology.
3. The International Telecommunication Union is active in areas including broadband Internet, latest-generation wireless technologies, aeronautical and maritime navigation, radio astronomy, satellite-based meteorology, convergence in fixed-mobile phone, Internet access, data, voice, TV broadcasting, and next-generation networks.
4. The International Telecommunication Union is based in Geneva, Switzerland, is a member of the United Nations Development Group and its membership includes 193 Member States and around 700 Sector Members and Associates.
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Role of Genes versus Environment
1. Inheritance is usually not Mendelian, however, and it is difficult to distinguish the role of genes and environmental factors. Adoptees more closely resemble their biologic than adoptive parents with respect to obesity, providing strong support for genetic influences. Likewise, identical twins have very similar BMIs whether reared together or apart, and their BMIs are much more strongly correlated than those of dizygotic twins. These genetic effects appear to relate to both energy intake and expenditure.
2. Whatever the role of genes, it is clear that the environment plays a key role in obesity, as evidenced by the fact that famine prevents obesity in even the most obesity-prone individual. In addition, the recent increase in the prevalence of obesity in the United States is far too rapid to be due to changes in the gene pool. Undoubtedly, genes influence the susceptibility to obesity in response to specific diets and availability of nutrition. Additional environmental factors may contribute to the increasing obesity prevalence. Both epidemiologic correlations and experimental data suggest that sleep deprivation leads to increased obesity.
3. Cultural factors are also important – these relate to both availability and composition of the diet and to changes in the level of physical activity. In industrial societies, obesity is more common among poor women, whereas in underdeveloped countries, wealthier women are more often obese. In children, obesity correlates to some degree with time spent watching television. Although the role of diet composition in obesity continues to generate controversy, it appears that high-fat diets may promote obesity, especially when combined with diets rich in simple (as opposed to complex) carbohydrates.
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Applications of radar
1. The information provided by radar includes the bearing and range (and therefore position) of the object from the radar scanner. It is thus used in many different fields where the need for such positioning is crucial. The first use of radar was for military purposes: to locate air, ground and sea targets. This evolved in the civilian field into applications for aircraft, ships and roads.
2. In aviation, aircraft are equipped with radar devices that can warn of obstacles in or approaching their path and give accurate altitude readings. They can land in fog at airports equipped with radar-assisted ground-controlled approach (GCA) systems, in which the plane's flight is observed on radar screens while operators radio landing directions to the pilot.
3. Marine radars are used to measure the bearing and distance of ships to prevent collision with other ships, to navigate and to fix their position at sea when within range of shore or other fixed references such as islands, buoys, and lightships. In port or in harbour, vessel traffic service radar systems are used to monitor and regulate ship movements in busy waters.
4. Radar has invaded many other fields. Meteorologists use radar to monitor precipitation. It has become the primary tool for short-term weather forecasting and to watch for severe weather such as thunderstorms, tornadoes, winter storms, precipitation types, etc.
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Light
1. The form of energy that illuminates our world is called light. It usually comes from hot objects, like the sun or fire, but it is also produced by electricity and some chemical reactions. Light is the only part of the electromagnetic spectrum (which includes microwaves, ultraviolet rays, and X-rays) that is invisible to the human eye. It travels at 186,000 miles (300,000 km) per second, and nothing can travel faster. Like other forms of energy, light travels in waves, but it can also travel in packets of energy called quanta. This enables it to travel through a vacuum.
2. Light rays are reflected when they hit a shiny or silvered surface, such as a still pool of water or a mirror. Reflection involves two light rays: the incoming ray and the reflected ray which bounces off the reflecting surface. The two rays are at identical angles to the reflecting surface on either side of an imaginary line.
3. Refraction is a property of all types of energy that travel in waves, including light. Light waves normally travel in straight lines, but when they pass from one transparent material to another, they usually refract, or bend. Refraction occurs because light travels at different speeds in different materials. As light from a material with a low density, such as air, enters a material with a high density, such as water, its speed is reduced. This causes it to bend (except when it enters a material at a right angle).
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Respiratory symptoms
1. Cough may indicate the presence of lung disease, but cough per se is not useful for the differential diagnosis. The presence of sputum accompanying the cough often suggests airway disease and may be seen in asthma, chronic bronchitis, or bronchiectasis.
2. Hemoptysis can originate from disease of the airways, the pulmonary parenchyma, or the vasculature. Diseases of the airways can be inflammatory (acute or chronic bronchitis, bronchiectasis, or cystic fibrosis) or neoplastic (bronchogenic carcinoma or bronchial carcinoid tumors). Parenchymal diseases causing hemoptysis may be either localized (pneumonia, lung abscess, tuberculosis, or infection with Aspergillus) or diffuse (Goodpasture's syndrome, idiopathic pulmonary hemosiderosis). Vascular diseases potentially associated with hemoptysis include pulmonary thromboembolic disease and pulmonary arteriovenous malformations.
3. Chest pain caused by diseases of the respiratory system usually originates from involvement of the parietal pleura. As a result, the pain is accentuated by respiratory motion and is often referred to as pleuritic. Common examples include primary pleural disorders, such as neoplasm or inflammatory disorders involving the pleura, or pulmonary parenchymal disorders that extend to the pleural surface, such as pneumonia or pulmonary infarction.
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Wireless technology
1. Wireless telecommunications, is the transfer information between two or more points that are physically not connected. Distances can be short, as a few meters as in television remote control; or long ranging from thousands to millions of kilometers for deep-space radio communications. It encompasses various types of fixed, mobile, and portable two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking.
2. Wireless operations permit services, such as long range communications that are impossible or impractical to implement with the use of wires. The term is commonly used in the telecommunications industry to refer to telecommunications systems which use some form of energy to transfer information without the use of wires.
3. The world's first wireless telephone conversation occurred in 1880, when Alexander Graham Bell and Charles Sumner Tainter invented and patented the photophone, a telephone that conducted audio conversations wirelessly over modulated light beams. In that distant era when utilities did not yet exist to provide electricity, and lasers had not even been conceived of in science fiction, there were no practical applications for their invention, which was highly limited by the availability of both sunlight and good weather.
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ELECTRICITE
1. Les lignes électriques et les pylônes haute et très haute tension constituent une nuisance visuelle indéniable: leur présence dégrade la qualité et l’esthétisme des paysages, et le recours à l’enfouissement des lignes est très limité par les producteurs d’électricité car très couteux. Mais elles sont également une source d'inquiétude en matière de santé publique. L’exposition aux champs électromagnétiques des populations riveraines aux pylônes haute tension suscite beaucoup d’interrogations: quelles sont les incidences sur la santé humaine d’une telle exposition prolongée?
2. Les riverains des pylônes haute tension sont exposés à des champs électriques et magnétiques à l'intérieur même de leur habitat: l’intensité dépend de nombreux facteurs, et notamment de la distance par rapport aux lignes de transport, des appareils électriques présents dans la maison ou encore de la configuration des conducteurs électriques intérieurs.
3. Les établissements industriels regorgent également de matériels électriques et de câbles conducteurs auxquels sont exposés leurs employés tout au long de leur journée de travail.
Les premières études ont démontré un lien entre les lignes haute tension et la santé.
«II y a des indications limitées issues de l’épidémiologie sur une relation possible entre les expositions à des champs magnétiques d’extrêmement basse fréquence et la leucémie de l’enfant» selon le Conseil Supérieur d’Hygiène Publique de France.
4. Une étude britannique publiée par les chercheurs de l'Université d'Oxford, démontre l'augmentation de 69 % des risques de leucémies pour les enfants dont le domicile se situe à moins de 200 mètres d'une ligne haute tension.Selon l’Organsation Mondiale de la Santé (OMS), certains chercheurs ont signalé que «les champs ELF (fréquences extrêmement basses) pourraient supprimer la sécrétion de mélatonine, une hormone associée au rythme circadien. L'hypothèse a également été émise que la mélatonine pourrait avoir un effet protecteur contre le cancer du sein, de sorte que sa suppression pourrait contribuer à une augmentation de l'incidence des cancers de cet organe induits par d'autres substances».
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