CANCER - GENERAL |
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Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these cells to invade other tissues, either by direct growth into adjacent tissue through invasion or by implantation into distant sites by metastasis. This unregulated growth is caused by damage to DNA, resulting in mutations to genes that encode for proteins controlling cell division. Many mutation events may be required to transform a normal cell into a malignant cell. These mutations can be caused by chemicals or physical agents called carcinogens, by close exposure to radioactive materials, or by certain viruses that can insert their DNA into the human genome. Mutations occur spontaneously, or are passed down generations as a result of germ line mutations.
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TELECOMMUNICATIONS |
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Telecommunications is the communication of information over a distance. The term is most used to refer to communication using some type of signalling, such as the aldis lamp or the transmission and reception of electromagnetic energy. This covers many media and technologies including radio, fiber optics, telegraphy, television, telephone, data communication and computer networking, although other types of signalling are also included (see Telecommunications History and especially Early Telecommunications).
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