PASSAGE 1: Bionic Men and Women
In the movie Star Wars: The Empire Strikes Back,Luke Skywalker loses a hand but get a new one, artificial hand that looks and works just like a real one. This is not unusual in sci-fi movies that take place far into the future. It is easy to believe that 100 years from now, doctors will be able to replace parts of the body with machines. But you do not have to go to the movies to see this happen.
Machines are already doing the jobs of various parts of the human body. There are people who can see, hear, walk, or pick up their children of artificial eyes, ears, legs, and arms. These are all possible because of developments in the field of bionics. Bionics means the study of how living things are made and how they work. Engineers study bionics to design machines that are similar to living things, For example, in order to design airplanes engineers have studied birds. The field of bionics also includes building machines to replace parts of the body or to support processes within the body.
One example of a bionic device is the pacemaker. A pacemaker can help someone whose heart beats too slowly or not regularly enough. The device goes into the person's chest and is attached to the heart with wires. The wires carry small amounts of electricity to the heart from a battery .That keeps the heart beating as it should.
Other bionic devices, like Luke skywalker's new hand, take the place of a part of the body. A major problem in developing bionic devices has been setting up communication between the body and the machine. Normally, the brain tells parts of the body what to do by sending messages along nerves. For example, your brain might send a message to your hand telling it to pick up a pen and write. But how would it tell an artificial hand to do that? Dr. William Craelius, who has invented an artificial hand, says, "Communication is key, and it is getting easier.
Machines are not the only things that can replace a part of the body. A transplant is an operation to move a body part, such as a heart or kidney, from one person to another. One major problem with transplants is a lack of available hearts, kidneys, and so on, so hospitals cannot keep up with the demand. Patients have to wait, and some patients have no time left. Therefore many scientists see bionics as the best hope for the future. Using bionics a patient could get a new heart or kidney right away instead of waiting for a transplant. Other scientists disagree. They say that bionics is already a thing of the past, and they have a better idea: They are working on using animal parts for transplants.
Maybe in the future our choices will not be limited to bionic devices and transplant operations. Maybe science will take us in another direction. Consider the salamander. If it loses a leg, it can grow a new one. What if a person who lost a hand or a kidney could grow a new one? This may sound like something from another sci-fi movie, but it could happen. Researchers are studying the genes that let salamanders grow new legs, and they hope to learn how human beings might do the same thing.
Growing a new part of the body could be the best way to go. On the other hand, some people, if they had the choice, might prefer bionic devices. In sci-fi movies, you may have seen people become cyborgs--half human being, half machine--with bionic parts that give them special powers, such as super-human speed or strength. Think about it. If bionics could turn you into a superman, what would you do?
PASSAGE 2: Word of Mouth Advertising
Whether you want to or not, you probably see and hear ads every day. Ads are all around us and have been for a very long time. They have even been found painted on walls in the ruins of Pompeii and ancient Egypt. Advertising has come a long way since then, but it is still all about getting people's attention.
Back when few people could read, ads usually took the form pictures. A sign for a of shoemaker might have a picture of boot, and a sign for a baker might show a loaf of bread. Street callers were a common form of advertising, too. They were hired to announce in a loud voice what was for sale, where to find it, and how good it was, as in "Get your fresh fish, right here, right now! The best in town!"
In developing countries, some businesses still use street callers, and this form of advertising probably does not cost them very much. In other parts of the world, advertising has become much more sophisticated, and it costs a great deal. If you add up all the money spent on advertising around the world, it comes to the equivalent of hundreds of billions of U.S. dollars a year.