Children’s fun world
This page contains learning resources for children's, scientific stories, Science News and Stories.
Teaching swans to migrate
Earlier this century, hunting had reduced the number of trumpeter swans in North America to under 100. Today, thanks to conservation efforts, they number over 3500 in USA. However, they are no longer found in Canada because they have forgotten the traditional migrating routes which used to take them to Canada and back. How do you teach a swan which has been raised in captivity how to migrate? Birds normally learn to migrate from their parents. William Sladen, an American biologist, has discovered a way to take over the role that the bird’s parents play.
He begins by playing tapes of human voices and engine sounds of planets to chicks while they develop inside their eggs. By the time they hatch, the chicks are trained to associate these sounds with their parents. The next step is to fly a small plane along the migratory route. Chicks which have been exposed to human voices and engine sounds before birth will follow such a plane. After flying the route once, the young swans are able to migrate along the same path in subsequent seasons without assistance. As first step, this year a group of swans will be flown across a much shorter route, within USA. The ultimate goal is to refine this technique so that it can be used on a variety of migratory birds.
People who are blind can now use a guidance system using design techniques similar to those used in radio-detectors to prevent shoplifting.In shops, radio-detectors cause an alarm to go off if someone tries to remove something containing an electronic label. In the guidance system, the labels or “transponders” are stuck to walls and floors. They mark out routes in a building. Blind people carry a tiny radio transmitter, mounted in a stick, which makes the transponder produce an echo. Different labels respond at different frequencies. These are used to generate an acoustic map of the surroundings for the blind user.
Hurricanes have a puzzling habit of devastating one house and leaving the house next door intact. Data from a mobile radar van has revealed what makes these violent storms appear so choosy.A hurricane can be hundreds of kilometers across, so researchers have been mystified as to why only certain areas get damaged. Meteorologists have found a reason for this strange behavior of hurricanes. They detected tubes of wind, like tornadoes turned on their side, each a few hundred metres across. One side of this tube takes fast moving wind from high up and spits it towards the ground. Areas near these down-draughts are blown over, but other areas are relatively safe from the storm. This is the reason why every “alternate “region gets destroyed.
A Computer with three hands
Human suffer from an inherent disadvantage in front of a computer. They do no have three hands: two for typing and one to operate a “mouse” which moves the “cursor” up and down the computer screen. The US company Sun Microsystems has designed a computer in which the user’s eye controls the text on its screen – leaving the hands free to work on the typewriter keyboard.How does it work? The monitor (screen) is equipped with an infrared light, which is shone into the eye. The user’s retina reflects it back to a sensor which determines the position of her gaze to within a centimeter.As the viewing eye moves, the text on the screen scrolls to keep pace. If the user stares long and hard at a passage, the image zooms to give a closer view.
The world’s first remote monitoring system giving early warning of volcanic eruptions has started functioning in Italy. Gas sensors that can withstand the hot, acid environments of volcanic vents will continuously measure emissions of random, hydrogen sulphide, methane, which often change before an eruption. Unusual changes in the levels of these gases will set off an alarm indication possible volcanic activity. The batplane Severe turbulence can disturb an aircraft and injure passengers. A new turbulence detector has been developed based on laser radar (lidar). The plane sends out laser pulses ahead, which may be reflected back by the particles in the air. This mimics the echo-sounding technique used by bats and dolphins. The lidar is to be improved using a more powerful beam. In the next few years, it might be standard equipment on commercial aircraft.
School Maths How can you send a coded message when the way you coded it is known? This is called public-key encryption. One much scheme is called RSA (after its three authors Rivest, Shamir and Adleman), where coding is done by “taking powers of” (exponentiating) the message. To decode the message, you have to take “discrete logarithms”, something which takes a lot of time (and can not be put in tables the way the usual logarithms are). Now there is a new scheme (called the Cayley-Purser), which uses matrix multiplication for coding. This makes the coding a lot faster, but not decoding. Says Sarah Flannery of Blarney, Ireland, “I have tired to show that in the places you can attack the code, it is hard as decoding RSA.” Sarah is a 16-year old schoolgirl who did this work during a two-week break at the company which developed the coding scheme. “She did a lot of mathematical analysis,” her colleagues said, proudly.Getting back to reality
Jan nick Rolland of the University of Central Florida, USA, was trying out a virtual reality helmet. She took the helmet off for a soft drink. She poured the drink on the top of her head instead of into her mouth. Why did she do that? That is what she and her colleague Frank Biocca of Michigan State University tried to find out. They found that hand-eye coordination gets affected by virtual reality, and it takes around half an hour before it is completely normal. Their research is being examined by surgeons who want to use virtual reality tools during surgery.
What will you do if the TV goes off while you are watching the World Cup? Before you run to catch your cable operator, make a note of when there last was a sunstorm. Every 11 years, sunspots, storms and flares on the sun reach a peak. Sometimes they send huge chunks of plasma (ions) in the direction of the Earth. These storms lead to wonderful displays of auroras (see the back cover) near the poles. More menacingly, when the last such storm hit Canada on 13 March 1989, power tripped and transformers failed all through the state of Quebec. We are now in for the next peak. Malaria vaccine?
Years of research have failed to produce a successful malaria vaccine. Yet an inter-national groups, including scientists at the National Institute of Immunology in New Delhi, are again hopeful. A new vaccine which attacks the malarial parasite, plasmodium falciparum, at several stages of its life-cycle using 9 different antigens, has been successful on rabbits.It is now being tested on monkeys. If that succeeds human tests will began next year. Another Continent?
The continent of Gondwanaland broke up more than 13 crore years ago into Antarctica, Australia and India. Australian scientists have now found that it may not have been that simple. Under the Indian Ocean, there are remnants of what may have been yet another continent-sized block of Gondwana. Its remains today may stretch from the Kerguelen Islands on the Tropic of Capricorn to the Andaman Islands north of the Equator. The fastest legs
Cockroaches can turn 25 times a second, making them the most nimble-footed animals known, say Jeff Camhi and his team at the Hebrew University of Jerusalem, Israel. They used film camera recording 250 frames a second. It seems to be their long antennae, to whose signals the brain responds, that makes the cockroaches do it. The question now is: how is their nervous system so efficient?The tiniest PC
Computer scientist Vaughan Pratt of Stanford University, USA, has made the world’s smallest personal computer. It has a 486 processor, 16 megabytes of memory, no hard disk, runs the Linux operating system, and has a website of its known on the Internet.If you don’t understand what all that means, don’t worry. It works more or less like a normal computer.What is not so normal is that it is about the size of a matchbox. Pratt is interested in building wearable computers. If you can get to the internet, you can try looking up this computer at the Internet address And while we are on the subject, researchers at the Visible Human project at the National Library of Medicine, National Institute of Health, USA, have put up two human bodies at the Internet address www.nlm.nih.gov/research/visible_human.html. The idea was for medical students to study anatomy without dissections.
Some time ago I received a call from a colleague. He was about to give a student a zero for his answer to a physics question, while the student claimed a perfect score. The instructor and the student agreed to an impartial arbiter, and I was selected.
I read the examination question: “show how it is possible to determine the height of a tall building with the aid of a barometer.
The student had answered, “Take the barometer to the top of the building, attach a long rope to it, lower it to the street, and then bring it up, measuring the length of the rope. The length of the rope is the height of the building.”
The student really had a strong case for full credit since he had really answered the question completely and correctly! On the other hand, if full credit were given, it could well contribute to a high grade in his physics course and to certify competence in physics, but the answer did not confirm this.
I suggested that the student have another try. I gave the student six minutes to answer the question with the warning that the answer should show some knowledge of physics. At the end of five minutes, he had not written anything. I asked if he wished to give up, but he said he had many answers to this problem; he was just thinking of the best one. I excused myself for interrupting him and asked him to please go on. In the next minute, he dashed off his answer which read:
“Take the barometer to the top of the building and learn over the edge of the roof. Drop the barometer, timing its fall with a stopwatch. Then, using the formula x = 0.5 at2, calculate the height of the building.”
At this point, I asked my colleague if he would give up. He conceded, and gave the student almost full credit. While leaving my colleague’s office, I recalled that the student had said that he had other answers to the problem, so I asked him what they were.
“Well said the student, “there are many ways of getting the height of a tall building with the aid of a barometer. For example, you could take the barometer out on a sunny day and measure the height of the barometer, the length of its shadow, and the length of the shadow of the building, and by the use of simple proportion, determine the height of the building.”
“Fine,” I said,“ and others?”
“Yes,” said the student, “there is a very basic measurement method you will like. In this method, you take the barometer and begin to walk up the stairs. As you climb the stairs, you mark off the length of the barometer along the wall. You can count the number of marks, and this will give you the height of the building in barometer units.”
“A very direct method”
“Of course. If you want a more sophisticated method; you can tie the barometer to the end of a string, swing it as a pendulum, and determine the value of g at the street level and at the top of the building. From the difference between the two values of g, the height of the building, in principle, can be calculated.”
“On this same tack, “you could take the barometer to the top of the building, attach a long rope it, lower it to just above the street, and then swing it is a pendulum. You could then calculate the height of the building by the period of the precession.”
“Finally,” he concluded, “three are many other ways of solving the problem.
Probably the best,” he said, “is to take the barometer to the basement and knock on the superintendent’s door. When the superintendent answers, you speak to him as follows: ‘Mr. Superintendent, here is a fine barometer. If you will tell me the height of the building, I will give you this barometer.”
At this point, I asked the student if he really did not know the conventional
Answer to this question. He admitted that he did, but said that he was fed up with high school and college instructors trying to teach him how to think.
[As the story goes, the student was Niels Bohr and the arbiter Rutherford.However, we are not completely sure of their identities. (Eds.)]
Meet Mr Kannappan
I am going to talk to you about my father’s friend, Mr Kannappa. We refer to him as “Kanakku” (Maths) Kannappan. I can hear you say, “Oh, an enthusiastic Maths teacher, eh?” Not at all! Kannappan uncle has nothing to do with schools. He turns a bookshop. He also reads a lot.
Why do we call him Maths Kannappan? Well, he is extremely fond of mathematics. He reads maths books the way we all read novels, hours on end. Before I met him, it had never occurred to me that anybody could read mathematical material like that. Often when business is not brisk in his shop, he can be seen with pen and paper on hand, absorbed in thought. The paper would be filled with strange symbols and pictures. Why, even his talk is usually influenced by maths.
When someone asks us the way to get somewhere, we say something like, “go straight down, and turn right when you see a palm tree.” In that situation, Mr Kannappan would typically say, “If you go south down the road approximately a kilometer, you should see a lonely palm tree about 15 feet tall, standing at an angle of 20 degrees to the vertical. That is when you should turn west.
Once when I was in his shop, a customer was asking about a book which was not available. Kannappan uncle told him that he would get the book for him that he would get the book for him. The customer said. “I will come next week, be certain to get the book,” and left. Uncle turned to me and said, “To be fair, I cannot have more than a 65% guarantee of getting the book for him next week.”
I was astounded “What do you mean? Why 65%?”
“Well, I would certainly like to go to the publishing company. Still the changes that will actually go there should be put at 90%. I am reasonably confident that would have this book in stock. Still there is a small 10% chance of it being out-of-stock. The chances that they quote a price which I can afford (and which my customer will accept) can be put at 80%. Thus the guarantee that it all happens the way I want it is 90/100 x 90/100 x 80/ 100 = 64.5 %!”
It took a while for it to sink into me that even through each of these seemed close to certain, the net effect looked bad. When I bemoaned the fact, Kannappan uncle signed. “If I tell my customer that there is a 65% chance if his getting the book next week, he won’t come at all!”
Mr Kannappan also loves to play with words. Here is one of his sentences: I am the King whose armies include fighting elephants.” Notice anything interesting? Count the numbers of letters in each word! (Try making sentences with word lengths 4313134 etc. It can be lots of fun!)
Once when my father said, “You should never believe anything any one says these days. “Kannappan uncle immediately retorted: “What about you said just now? Shall I believe that?” Do you get it?
I had always thought of mathematics as symbols, sums, x, y, z, etc. Mr Kannappan opened out a whole new world, full of interesting things and new ways of thinking. I keep learning from him.
A question of Profit
Once Priya and I had gone to Mr Kannappan’s book shop. A customer came in when we were there. He asked. “The book I bought yesterday turned out to be difficult for me to read. I have brought it with me, will you take it back?”
This was a book called Indian Economy by one Dr Athreya. Kannappan uncle tried –“It is quite a good book, really. The style may be a little difficult, but it’s worth trying.”
The customer wasn’t convinced, and uncle told him, “OK then. You bought it for Rs 10 did you not? I will take it back and give you Rs 8.” The customer murmured about the “rent” of Rs 2, but returned the book.
What is “economy”? I know very little about such things, and Priya (I’m sure!) knows less than I do.
We were asking Kannappan uncle about it when another customer showed up. He stayed for a while leafed through several books, picked up a few, conducted a long conversation, and just as he was ready to pay up, noticed the Indian Economy book. “Ah, isn’t this a good book, though rather old fashioned now? Maybe I should read it.”
“Sure, you should read it. It costs Rs 10. Well, you owe me Rs 41 for all the rest, so make it Rs 50 and take this book with you”
The customer seemed happy to do that. He paid up and left.
Kannappan turned to us and said with twinkle in his eye, “Before you learn economics, do you your profit-and –loss sums right? Here, tell me how much profit I made on that book?”
Priya was fast and shouted right away, “Three rupees!” Her calculation turned out to be as follows:
|Sold to customer I yesterday for||Rs 10|
|Bought from him today for||Rs 8|
|Net profit||Rs 2|
|Bought from Customer 1 today for||Rs 8|
|Sold to Customer 1today for||Rs 9|
|Net profit||Re 1|
|Total profit||Rs 3|
I saw the flaw in her sum with great glee. I said, “No way! Of course, it is true that you made Rs 2 from the first customer, but you sold a ten rupee book for only Rs 9 to the second, so you incurred a loss of one rupee today. So the net profit is only one rupee!”
I thought I had uncovered a deep truth, so I felt uneasy when uncle just laughed aloud saying “what logic!” When we pressed him for the right answer, he did what irritates us most-sent us off saying, “Think about it yourself, we will discuss it tomorrow.”
That night Priya and I button holed our father about this problem. He scratched his head and shrugged. “Kannappan keeps confusing people like this. When children ask, he should explain.Really a useless fellow!”
Our mother was more enthusiastic. “Kannappan’s puzzles are always fun! Raju, Priya, you are both wrong. His profit is two rupees,” she asserted.
We pressed her, and she gave us a strange argument: How did the book earn a profit of Rs 2 from the first customer? Because of being sold for Rs 10 and bought for Rs 8. This makes the value of the book Rs 9. So when it was sold for Rs 9 a second time, there was no additional profit. Thus the net profit was two rupees.
Neither Priya nor I agreed with her. Father only managed to confuse matters further.
When we met Kannappan uncle the next day, he dropped a bombshell. “None of your calculation is right,” he said, Can you guess the explanation he gave?
Source: Portal Content team