Search

How do Internet search engines work? Javed Mostafa, Victor H. Yngve Associate Professor of Information Research Science and director of the Laboratory of Applied Informatics, Indiana University, offers this answer: Publicly available Web services--such as Google, InfoSeek, Northernlight and AltaVista--employ various techniques to speed up and refine their searches. One way to save search time is to match the Web user's query against an index file of preprocessed data stored in one location, instead of sorting through millions of Web sites. To update the preprocessed data, software called a crawler is sent periodically by the database to collect Web pages. A different program parses the retrieved pages to extract search words. What is quicksand? Darrel G. F. Long, a sedimentologist in the department of earth sciences, Laurentian University in Sudbury, Ontario, explains: Quicksand is a mixture of sand and water or of sand and air; it looks solid but becomes unstable when it is disturbed by any additional stress. Grains frequently are elongated rather than spherical, so loose packing can produce a configuration in which the spaces between the granules, or voids, filled with air or water make up 30 to 70 percent of the total volume. In quicksand, the sand collapses, or becomes "quick," when force from loading, vibration or the upward migration of water overcomes the friction holding the particles in place. In quicksand, the sand collapses, or becomes "quick," when force from loading, vibration or the upward migration of water overcomes the friction holding the particles in place. Most quicksand occurs in settings where there are natural springs, such as at the base of alluvial fans (cone-shaped bodies of sand and gravel formed by rivers flowing from mountains), along riverbanks or on beaches at low tide.