Прочитайте текст и выполните задания AIDS 1. AIDS is a sickness that attacks the body’s natural syst...: ответ на тест 1077964 - Английский язык

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AIDS
1. AIDS is a sickness that attacks the body’s natural system against disease. AIDS itself doesn’t kill, but because the body’s defence system is damaged, the patient has a reduced ability to fight off many other diseases, including flu or the common cold. Since its discovery, AIDS has caused nearly 30 million deaths (as of 2009). As of 2010, approximately 34 million people are living with HIV globally. AIDS is considered a pandemic – a disease outbreak which is present over a large area and is actively spreading. Africa and South America are the continents where AIDS is most rampant.
2. So far there is no cure for AIDS. We know that AIDS is caused by a virus which invades healthy cells, including the white blood cells that are part of our defence system. The virus takes control of the healthy cells genetic material and forces the cell to make a copy of the virus. The cell then dies and the multiplied virus moves on to invade and kill other healthy cells.
3. The AIDS virus can be passed on sexually or by sharing needles used to inject drugs. It also can be passed in blood products or from a pregnant woman with AIDS to her baby. Many stories about the spread of AIDS are false. One cannot get AIDS by working with someone who’s got it, or by going to the same school, or by touching objects belonging to or touched by an infected person. Nobody caring for an AIDS patient has developed AIDS.
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Why is the AIDS virus so dangerous?

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AIDS
1. AIDS is a sickness that attacks the body’s natural system against disease. AIDS itself doesn’t kill, but because the body’s defence system is damaged, the patient has a reduced ability to fight off many other diseases, including flu or the common cold. Since its discovery, AIDS has caused nearly 30 million deaths (as of 2009). As of 2010, approximately 34 million people are living with HIV globally. AIDS is considered a pandemic – a disease outbreak which is present over a large area and is actively spreading. Africa and South America are the continents where AIDS is most rampant.
2. So far there is no cure for AIDS. We know that AIDS is caused by a virus which invades healthy cells, including the white blood cells that are part of our defence system. The virus takes control of the healthy cells genetic material and forces the cell to make a copy of the virus. The cell then dies and the multiplied virus moves on to invade and kill other healthy cells.
3. The AIDS virus can be passed on sexually or by sharing needles used to inject drugs. It also can be passed in blood products or from a pregnant woman with AIDS to her baby. Many stories about the spread of AIDS are false. One cannot get AIDS by working with someone who’s got it, or by going to the same school, or by touching objects belonging to or touched by an infected person. Nobody caring for an AIDS patient has developed AIDS.
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Why is the AIDS virus so dangerous?

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Poliomyelitis
1. Poliomyelitis is an acute, viral, infectious disease spread from person to person, primarily via the fecal-oral route. The term means inflammation of the spinal cord’s grey matter, although a severe infection can extend into the brainstem and even higher structures, resulting in polioencephalitis, producing apnea that requires mechanical assistance such as an iron lung.
2. Although approximately 90% of polio infections cause no symptoms at all, affected individuals can exhibit a range of symptoms if the virus enters the blood stream. In about 1% of cases, the virus enters the central nervous system, preferentially infecting and destroying motor neurons, leading to muscle weakness and acute flaccid paralysis. Different types of paralysis may occur, depending on the nerves involved. Spinal polio is the most common form, characterized by asymmetric paralysis that most often involves the legs. Bulbar polio leads to weakness of muscles innervated by cranial nerves. Bulbospinal polio is a combination of bulbar and spinal paralysis.
3. Poliomyelitis was first recognized as a distinct condition by Jakob Heine in 1840. Its causative agent, poliovirus, was identified in 1908 by Karl Landsteiner. Although major polio epidemics were unknown before the late 19th century, polio was one of the most dreaded childhood diseases of the 20th century. Polio epidemics have crippled thousands of people, mostly young children; the disease has caused paralysis and death for much of human history. Polio had existed for thousands of years quietly as an endemic pathogen until the 1880s, when major epidemics began to occur in Europe; soon after, widespread epidemics appeared in the United States.
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The History of Answering Machines
1. Valdemar Poulsen, the Danish telephone engineer and inventor, patented what he called a telegraphone in 1898. The telegraphone was the first practical apparatus for magnetic sound recording and reproduction. It was an ingenious apparatus for recording telephone conversations. It recorded, on a wire, the varying magnetic fields produced by a sound. The magnetized wire could then be used to play back the sound. That was the first automatic answering machine
2. Mr. Willy Müller invented the first automatic answering machine in 1935. This answering machine was a three-foot-tall machine popular with Orthodox Jews who were forbidden to answer the phone on the Sabbath. The Ansafone, created by inventor Dr. Kazuo Hashimoto for Phonetel, was the first answering machine sold in the USA, beginning in 1960.
3. CASIO COMMUNICATIONS created the modern telephone answering device (TAD) industry as we know it today by introducing the first commercially viable answering machine a quarter of a century ago. In 1971, PhoneMate introduced one of the first commercially viable answering machines, the Model 400. The unit weighs 10 pounds, screens calls and holds 20 messages on a reel-to-reel tape. An earphone enables private message retrieval. The first digital tad was invented by Dr. Kazuo Hashimoto of Japan in mid-1983. US patent 4,616,110 entitled Automatic Digital Telephone Answering.
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What is inside a typical satellite?
1. Satellites come in all shapes and sizes and play a variety of roles. For example, weather satellites contain cameras that can return photos of Earth's weather, either from fixed geostationary positions or from polar orbits. Communications satellites allow telephone and data conversations to be relayed through the satellite. The most important feature of a communications satellite is the transponder – a radio that receives a conversation at one frequency and then amplifies it and retransmits it back to Earth on another frequency. A satellite normally contains hundreds or thousands of transponders. Broadcast satellites broadcast television signals from one point to another (similar to communications satellites).
2. Scientific satellites perform a variety of scientific missions. The Hubble Space Telescope is the most famous scientific satellite, but there are many others looking at everything from sun spots to gamma rays. Navigational satellites help ships and planes navigate. Rescue satellites respond to radio distress signals. Military satellites are up there, but much of the actual application information remains secret. Applications may include relaying encrypted communication, nuclear monitoring, observing enemy movements, early warning of missile launches, eavesdropping on terrestrial radio links, radar imaging, photography.
3. Despite the significant differences between all of these satellites, they have several things in common. All of them have a radio system and antenna. At the very least, most satellites have a radio transmitter/receiver so that the ground-control crew can request status information from the satellite and monitor its health. Many satellites can be controlled in various ways from the ground to do anything from change the orbit to reprogram the computer system.
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Cell-phone channels
1. A single cell in an analog cell-phone system uses one-seventh of the available duplex voice channels. That is, each cell (of the seven on a hexagonal grid) is using one-seventh of the available channels so it has a unique set of frequencies and there are no collisions. A cell-phone carrier typically gets 832 radio frequencies to use in a city. Each cell phone uses two frequencies per call – a duplex channel – so there are typically 395 voice channels per carrier.
2. Therefore, each cell has about 56 voice channels available. In other words, in any cell, 56 people can be talking on their cell phone at one time. Analog cellular systems are considered first-generation mobile technology, or 1G. With digital transmission methods (2G), the number of available channels increases. For example, a TDMA-based digital system (more on TDMA later) can carry three times as many calls as an analog system, so each cell has about 168 channels available.
3. Cell phones have low-power transmitters in them. Many cell phones have two signal strengths: 0.6 watts and 3 watts (for comparison, most CB radios transmit at 4 watts). The base station is also transmitting at low power. Low-power transmitters have two advantages. The transmissions of a base station and the phones within its cell do not make it very far outside that cell. The power consumption of the cell phone, which is normally battery-operated, is relatively low. Low power means small batteries, and this is what has made handheld cellular phones possible.
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