Friday 13 November 1998
Yes, and people who go to their GP reporting a loss of either sense are, after testing, found to be either completely without smell or taste sensations or they may have a reduced sensitivity to particular tastes or smells. In some disorders of the chemical senses, the system may misread and distort a smell, a taste, or a flavour. Or a person may detect a bad smell or taste from a substance that is normally nice. Smell disorders are more common than taste disorders and both are potentially serious. A person with faulty chemosenses is deprived of an early warning that most of us take for granted. Smell and taste alert us to fires, poisonous fumes, leaking gas, and spoiled food and beverages. Smell and taste losses can also lead to depression because eating just isn't fun anymore.
Some people are born with poor senses of taste or smell, but most develop them after an injury or illness. Upper respiratory infections and head injuries are frequently blamed. Loss of the sense of smell can result from polyps in the nasal cavities, sinus infections, hormonal disturbances, or dental problems. Loss of smell and taste also can be caused by exposure to chemicals such as insecticides and by some medicines. For example, many patients find that their sense of taste and smell is affected after receiving radiation therapy for cancers of the head and neck.
The extent of a particular person's problem can be determined by measuring the lowest concentration of a chemical that he or she can detect. A patient also may be asked to compare the smells or tastes of different chemicals or to note how the intensities of smells or tastes grow when a chemical's concentration is increased. Scientists have developed a "scratch and sniff" test to evaluate smell. A person scratches pieces of paper treated to release different smells, sniffs them, and tries to identify each one from a list. In taste testing, the patient responds to different chemical concentrations: this may involve a simple "sip, spit, and rinse" test, or chemicals may be applied to areas of the tongue.
Q: Who was the first person to wear a watch?
The first known recorded wrist watch was made by two Swiss men - Jaquet- Droz and Leschot in Geneva in 1790. It was a "watch to be fixed to a bracelet". The earliest surviving example is from 1806.
Q: How long and at what height and speed does the space shuttle orbit?
The type of orbit depends on the shuttle's mission. The Hubble repair mission was conducted at a record shuttle altitude of about 359 miles because that was where Hubble was positioned.
The STS 70 mission which carried the Russian cosmonaut Sergei Krikalev, reached about 220 miles. The lower the orbit, the higher the orbital speed.
The speed of 160-mile high circular orbital speed would be about 17,750mph. There is not much difference between orbital speeds from 160 to 350 miles. One orbit takes about 90 minutes.
You can also visit the technoquest World Wide Web site at http://www.sciencenet.org.uk
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