Around the sun leaving a bright trail behind. For more than
Yüklə 2,03 Mb.
|
A laser is a very strong beam of light which is very different from ordinary light. Today, doctors use lasers in some eye operations. They use them when operating on a patient who has a detached (i.e. separated) retina. The retina is the inner back part of the eye, the part that senses light. Light from an object must strike the retina for seeing to occur. In the past, a detached retina caused blindness in the eye. Now, the laser makes delicate eye operations possible, and a detached retina no longer means the loss of sight. By carefully directing this super light beam, the doctor can weld the retina to the rest of the eye again. The welding of the retina takes less than a thousandth of a second and is done without anesthesia. Anesthetizing the patient is not necessary, because the patient feels no pain. Doctors also want to use lasers in operations on people who have heart diseases. In the United States and Canada alone, more than 1.5 million people suffer from heart diseases every year. Most of these are related to the flow of blood through the coronary arteries, which supply the majority of the blood to the heart. People who have a heart disease have a high amount of cholesterol in their blood. Cholesterol builds up fatty deposits called ‘plaques’ on the inner walls of the aıteries. As the plaques get bigger, the opening of the arteıy g smaller. When it is completely closed. blood stops flowing and i heart attack occurs. Some doctors are planning to use lasers to destroy these fa 25 deposits in the near future. More studies are needed, but some doct feel this plan will he beneficial for heart patients. At present, thou lasers have many other uses in hospitals; theyare used in steriliz instroments, stopping bleeding and removing birthmarks.
ENGINEERING IN CHARGE Do you realise that every time you take a step, the bones in your hip are subjected to forces between four and five times your body weight? When you are running, this force is increased further still. What happens if, through disease, a hip-joint ceases to be able to resist such forces? Like all fantasies, the Bionic Man has an element of reality in ft and for many years, hip-joints and other body joints have been replaceable partially or completelye it is, after all, a simple ball and socket joint; it has certain loads imposed on it; it needs reliability over a defined life, and it must contain materials compatible with the working environment. Any engineer will recognise these as characteristic of a typical engineering problem, which doctors and engineers have worked together to solve in order to bring a fresh lease of life to people who would otherwise be incapacitated. This typifies the way in which engineers work to help people and create a better quality of life. The fact that this country has the most efficient agricultural industry in the world is another prime example. Mechanical engineers have worked with farmers, horticulturalists and biologists to produce fertilisers, machinery and harvesting Systems. The paintings of Brueghel show farmers in the sixteenth century wading through shoulder-high cereal crops. This team effort has now produced crops uniformly waist-high or less so that they are more suitable for mechanical harvesting. Similar advances with other crops have released people from hard and boring jobs for more creative work, while machines harvest crops more efficiently with less waste. Providing more food for the rapidly increasing population is yet another role for the mechanical engineer.
Yüklə 2,03 Mb. Dostları ilə paylaş:
|