Archives August 2013

"The atoms become like a moth, seeking out the region of higher laser intensity." Steven Chu, physicist The carbon dioxide laser is considered the most useful and versatile type of laser. It was invented in 1964 by Kumar Patel (b. 1938) while he was working in the United States at Bell Laboratories, New Jersey. Carbon dioxide lasers emit infrared radiation with a wavelength between 9 and 11 micrometers. The active medium in the laser is a mixture of carbon dioxide, nitrogen, and helium. The nitrogen molecules, made to vibrate by an electric current, cannot lose this energy by electron emission, so they in turn excite the carbon dioxide molecules, which produce the laser light. The helium plays two roles; it assists the transfer from the gas of heat caused by the electric discharge, and it helps the carbon dioxide molecules to return to their ground state after excitation. The gas more...

"Age does not diminish the... disappointment of having...ice-cream fall from the cone." Jim Fiebig, columnist In 1846 Williams & Company—a small Philadelphia- based wholesaler of kitchen appliances—purchased the patent for a new hand-cranked machine that could speed up the process of making ice-cream. Over the next thirty years there would be more than seventy improvements to the machine they had shrewdly procured for a mere $200; but what Williams & Company could not buy, however, was the credit for having invented the machine. That distinction belongs  to a humble Philadelphia housewife named Nancy Johnson who lacked both the money and the business savvy to promote her invention and sold the patent to her machine, which went on to be marketed as "Johnson's Patent Ice-Cream Freezer." Nancy Johnson then proceeded to fade quietly back into the obscurity from whence she had come. Johnson's innovative design involved placing the ice-cream's ingredients of more...

Some of the recent events in the country have confirmed that military training should be imparted as a compulsory training to every able-bodied citizen of India. The wars with China and Pakistan and terrorist attacks have compelled the Indian leaders to give a second thought to this problem. Our leaders have realized that in order to meet the challenge, there must be a strong force that could prove to be morale-booster. So, the slogan "militaries the nation" has been coined. Getting training in military science is important and useful in ways more than one. That it makes the people disciplined, is beyond doubt. It also inculcates the noble qualities of service, sacrifice, devotion and dedication. Military training serves as an insurance against foreign attack. It keeps the people physically fit and intellectually sharp. It also increases the power to work. As a matter of fact, by imparting military training compulsorily more...

The car alarm is far from being a universally popular invention: a British television poll listed it as one of the United Kingdom's ten least favorite inventions (just behind the cell phone), and as mayor of New York Rudy Giuliani commented, "Noise pollution is a major problem. Even in a city as exciting as New York, people should be able to sleep without being disturbed by car alarms..." There have been petitions to ban the devices, and there have even been claims that car alarms, far from helping reduce instances of car theft, actually make the problem worse! The first recorded instance of car theft occurred in 1896. Cars are valuable and simple to "disguise," so thieves regard them as easy targets. Reputedly the product of car stereo manufacturers in California in 1970, the car alarm seems to offer the perfect solution; an automated alarm that will emit a loud more...

The mango is a fruit and is popularly known as the 'king of all fruits' in India due to its delicious taste. It is grown in plenty in Mumbai, Tamil Nadu, Bihar, Uttar Pradesh, West Bengal and other states. At the end of January, we can see blossoms in mango trees. At the end of March, these blossoms turn into little green mangoes. They gradually grow bigger. In the months of May and June, they become ripe. At that time they look very beautiful. Their colour becomes golden yellow and sometimes a little red. There are different varieties of mangoes like Bombay, Kishenbhog, Mohanbhog, Langra, Himsagar, Fazli, Bhadhuri etc. We eat mangoes by removing the skin. We also take the juice of ripe mangoes mixed with milk and sugar. The green mango is generally sour to taste. The people of our country cut green mangoes into small pieces and get more...

Until the mid-nineteenth century, the most powerful known explosive was gunpowder. In 1846 Italian chemist Ascanio Sobrero discovered that by nitrating glycerin he could make a fearsomely explosive liquid. It was also frighteningly unstable. Alfred Nobel (1833- 1896) undertook the dangerous task of turning nitroglycerin into a marketable product. Despite an explosion in 1864 that killed his brother and workers at the family's factory, he persisted with his experiments. Nobel's first success came from combining nitroglycerin with a mercury fulminate detonator. He began producing this explosive in bulk, but the frequency of accidents soon saw it banned in many countries. In 1866 Nobel discovered a mixture of nitroglycerin with diatomaceous earth, a chalklike sedimentary rock. He christened this comparatively safe explosive dynamite, from the Greek word for "power." Packed into paper tubes, dynamite was soon selling in vast quantities and revolutionized activities such as tunnel-building and quarrying. Dynamite, patented in more...

Long before the snowmobile, our ancestors found an environmentally friendly way to get around in the snow—the sledge. In fact, the sledge (and variations on its theme) was key in many areas of ancient life. A sled is a vehicle that moves by sliding across the ground. Sleighs are horse-drawn vehicles, with passenger seating. Sledges tend to be large vehicles consisting of a wooden base mounted on smooth runners, useful for transporting large objects. Evidence of wooden sledge usage reaches back to 7000 B.C.E., to peoples living in the Arctic regions of northern Europe. Initially sledges may have been pulled by humans, but with time dogs and oxen were commandeered to take the strain. Inuits have used dog-sleds since pre-Columbian times. Sledge use has extended to hotter climates, too, including the dry, dusty lands of Mesopotamia. Exactly where and when the sledge was developed is unknown, but it is likely more...

The study of human memory was greatly changed in 1943, when Warren McCulloch and Walter Pitts wrote a paper on how neurons might work. (Neurons are the cells that make up tissue in the part of the nervous system involved in learning and recognition.) Six years later, D. O. Hebb described the strengthening of neural connections that occurred each time they were used. In the early days of artificial intelligence research, Frank Rosenblatt (1928-1971)—a computer scientist at the Cornell Aeronautical Laboratory in New York—was studying how the eyes of a fly work. Rosenblatt observed that when a fly perceives danger, its reaction occurs faster than the information can be processed by its brain. He then produced the perceptron, the first computer to learn new skills using a neural network mimicking human thought processes. The perceptron had a layer of interconnected input and output nodes. Each connection is "weighted" to make more...

After India got Independence, a controversy was at its peak whether English should continue or not. The two views ? gave their own arguments in for and against the existence o; English in India after freedom. Some people opposed English because they thought that it was a foreign language, the language of the British and therefore with the end of their rule, their language should also be abolished. But it was not easy to abolish it at once. Hence it was given a lease of fifteen years and after that it was to be replaced by Hindi as the national and official language of the country. But when the time for the replacement of English by Hindi came, there was lot of opposition from all sides especially from the south. Nothing could be done in such an atmosphere and finally it was decided that English would remain the official language more...

Whether it is for a mobile phone or an iPod, the modern way of life relies upon rechargeable batteries.  The first steps along this path were taken by the French physicist Gaston Plante (1834-1889). Working in Paris in 1859, Plante invented the lead- acid cell. His device comprised a coil of lead for the negative plate and a coil of lead oxide for the positive plate; these were separated by rubber strips and bathed in a bath of dilute sulfuric acid. The sulfuric acid reacts with the lead, releasing electrons that pass to the positive plate, hence generating current. Existing cells ceased to produce current when the chemical reactants were spent. But, in the Plante arrangement, the reaction is reversed when current is added to the cell from an outside source, and in so doing the battery is recharged. Within a year, Plante had fitted nine of these units into more...