guide dog, a dog trained to lead a blind person. The first school for training such dogs was established by the German government after World War I for the benefit of blinded veterans. Schools now exist in several European countries and the United States, where the pioneer Seeing Eye, Inc., founded by Dorothy Harrison Eustis in 1929 and established near Morristown, N.J., in 1932, is the best known. The master spends about a month at the school training with the already trained dog and is usually charged a nominal fee. Although the German shepherd is by far the most widely used breed for guide-dog work, several other breeds, e.g., the golden retriever, the Labrador retriever, and the Doberman pinscher, have been trained successfully for this work. Approximately 10% of the blind population can use seeing-eye dogs successfully, that fraction including scores of persons who have achieved new independence through their assistance. Applicants may be rejected on the basis of sufficient useful vision, advanced age, poor health, or unsuitable temperament.

Device that constrains the path of electromagnetic waves (see electromagnetic radiation). It can be used to transmit power or signals in the form of waves while minimizing power loss. Common examples are metallic tubes, coaxial cables, and optical fibres (see fibre optics). Waveguides transmit energy by propagating transmitted electromagnetic waves through the inside of a tube to a receiver at the other end. Metal waveguides are used in such technologies as microwave ovens, radar systems, radio relay systems, and radio telescopes.

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or Seeing Eye dog

Dog professionally trained to guide and protect its blind master. They have also been used to assist persons with hearing impairments and restricted mobility. Systematic training of guide dogs originated in Germany during World War I to aid blinded veterans. At the age of approximately one year, the dog is trained for three or four months. Retrievers and German shepherds are the most widely used breeds.

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