Category Science

What is electroretinogram?

          The recording of potential changes produced by the eye when the retina is exposed to a flash of light is called the electroretinogram, or in short ERG. Retina is a light-sensitive area at the back of the eye connected to the brain by the optic nerve. To record an ERG, one electrode is mounted on contact lens that fits over the cornea and the other is attached above the ear or forehead.

          An ERG signal is more complicated than a nerve signal because it is the combination of the effects taking place within the eye. The general pattern of an ERG is shown in the figure. From the medical point of view, the ‘B’ wave is the most important because it arises in the retina. If a patient is suffering from ‘Retinitis pigmentosa’ the ‘B’ wave would be absent in his ERG because of the inflammation of the retina.

          The recording of the potential changes due to eye movement is called electroculogram. In short, it is known as EOG. To record an EOG, a pair of electrodes is attached near the eye. An EOG can record horizontal and vertical movements of the eye. EOG also provides information about the orientation of the eye, its angular velocity, and its angular acceleration. Scientists have studied the effects of drugs on the eye movement. By an ERG, eye movements during sleep can also be studied. EOG is very rarely used in the routine check up for eye ailments.

          Retina is an important part of the eye. It is a layer of special cells at the back of an eye ball and contains sensory cells capable of converting light into nervous messages that pass down the optic nerve to the brain. Images of the objects are formed on the retina. So with the help of an ERG, certain major diseases of the retina can be detected. Damage to the retina can cause blindness.

What is consciousness?

               The word consciousness in psychological term refers to the condition of alertness of the organism. The brain is the control centre of the body’s nervous system and plays a major role in man’s thinking, remembering, alertness and vice-versa. Unconsciousness refers to the state of sleeping. Between these two conditions one may have varying degrees of consciousness.

               In a condition of full consciousness the level of alertness will be very high. For example if someone is playing chess and wants to win, he would try to remain in a state of high alertness and deep concentration. Similarly the circus gymnasts would have to be very alert during their performances.

               If a person is dozing he is said to be in a state of lower level of consciousness. He would be regarded as unconscious if he falls asleep.

               These are different states of consciousness we come across in our normal day-to-day life. However, unconsciousness or sub-consciousness can also be produced by artificial means. A high state of consciousness can be produced with the help of some medicines which act as a stimulant to make person more active beyond his normal ability. Such medicines affect the central nervous system and produce such abnormal conditions. Caffeine in a strong coffee or tea can act as a powerful stimulant for some people. Too much alcohol can produce dozing effect and finally unconsciousness.

               Certain diseases have a marked impact on the level of consciousness. There are some mental diseases which can lower the consciousness of a person. Emotional disturbances also affect the state of alertness of an individual. Highly emotional people often get the feeling of depression.

               Today, scientists have developed several medicines and shock therapies which can control the level of consciousness. These methods are used for treating people with lower level of consciousness. However, these should be used only when prescribed by a physician. 

When was the first balloon flight made?

               Balloon flights have become a popular air sport these days though the number of participants is limited to a few. Balloon festivals are organized every year at different places all over the world as a competitive sport as well as for fun and entertainment. But who made the first balloon flight and when?

               The idea of a balloon flight first occurred in the mind of two Frenchmen when they watched smoke rising up inside a chimney. This led Joseph and Etienne Montgolfier to build the first man-carrying balloon. The balloon made by them was filled with hot air from a fire to provide the lift required for flying. It was the year 1783 when the people of Paris were amazed to see a sheep, a cock and a duck flying in a balloon made by Joseph and Etienne Montgolfier. But strangely the fact remains that though they made the first balloon they could not become the first air travellers. The honour of making the first balloon flight is shared by two brave men, J.P. de Rozier and Marquis d’ Arlandes. This historic flight carrying these two men was made in November, 1783. With this began the era of flying.

               But a balloon flight of this kind depended on wind blowing and the balloon flew in the direction of the wind. To overcome this drawback the first powered flight was made by fitting an engine to a balloon in the year 1852. Henri Gifford of Paris made this airship with a balloon fitted with hydrogen gas for lifting the balloon. A platform was attached below the balloon through wires and a small steam engine was fitted on this platform. The airship could be moved forwards with the help of a propeller run by the engine. This was the fore-runner of the more advanced airships and the later day aeroplanes which were run by electric and petrol engines.

               There are some interesting facts about the recent history of ballooning. A balloon called Miss Champagne rose to a height of 50 feet with 61 passengers on board on 19 Feb 1988.

               The Dutch balloonist Henk Brink made a balloon that reached a height of 328 feet with 50 passengers on board on 17 August 1988 which lasted for 25 minutes. 

What are Dr. S. Chandrasekhar’s contributions to astrophysics?

               Dr. Subrahmanyan Chandrasekhar was a world famous astrophysicist. He was awarded the Nobel Prize for physics in 1983 for his outstanding researches in the field of astronomy related to the structure and evolution of stars. He shared this prize with an American professor William Fowler. Do you know why he received this honour and what are his contributions to the astrophysics?

               Prof. Chandrasekhar was born on Oct 19th, 1910 in Lahore. He was educated at Presidency College, Madras University. He got his doctorate from Trinity College, Cambridge. From 1933 to 1937 he worked on stellar evolution. His genius is established from the fact that he became a Fellow of Trinity College at a young age of 24. And at the age of 25 he had put forth his theory on dying stars which startled the whole world.

               In 1938 he became an Assistant Professor in Chicago University and in 1953 acquired American citizenship. In the same year he was given the Gold medal of Royal Astronomical Society.

               In 1947 Dr. Chandrasekhar became a Professor in Chicago University and the Morton D. Hull Distinguished Service Professor of Astrology in 1952. His genius is evident from the fact that his book An Introduction to the study of Stellar Structure, published in 1939 is still used as a reference book for students of astrophysics all over the world.

               In 1973 he was made a member of the Swedish Academy that awards the Nobel Prizes. His findings on White Dwarfs are internationally acclaimed. ‘Chandrasekhar Limit’ that deals with the limiting mass of the stars is again an epoch making discovery by him.

               The Mathematical Theory of Black Holes was his most important work, published in 1983. His latest book was Newton’s Principia for the common reader. Prof. Chandrasekhar passed away as an American citizen in the year 1995, within a few weeks of the publication of this book.

 

What were Ramanujan’s contributions to mathematics?

               Srinivasa Ramanujan was one of the greatest mathematicians India has ever produced. His contributions to the theory of numbers brought him worldwide acclamation. He was born in a poor Brahmin family of south India on 22nd December, 1887. Due to lack of scope, he started his career as a clerk. In his spare time he used to devise mathematical Problems himself and solve them.

               When he was 15 years old he obtained a copy of George Shoobridge Carr’s Synopsis of Elementary Results in Pure and Applied Mathematics. Having verified the results in Carr’s book, Ramanujan went beyond and developed his own theorems. In 1903 he secured a scholarship from the University of Madras. But since he devoted himself fully to mathematics and neglected other studies it was forfeited the following year.

               But undeterred, Ramanujan continued with his work in extreme poverty without employment. He got married in 1909 and began to search for a permanent employment. He obtained a clerical post with the Madras port trust.

               Ramanujan published his first research papers in the journal of the Indian Mathematical Society in the year 1911. His genius slowly gained recognition and in 1913 he began a correspondence with the British mathematician Godfrey H. Hardy that led to a special scholarship from the University of Madras and a grant from Trinity College, Cambridge. In 1914 Ramanujan went to England, where Hardy tutored him privately and collaborated with him in some research.

               Ramanujan’s genius was unrivalled. He worked out the Riemann series, the elliptic integrals, hyper geometric series, and the functional equations of the Zeta function and his theory of divergence series. In England, Ramanujan made further advances, especially in the partition of numbers. His papers were published in English and European journals. In 1918 he became the first Indian to be elected as a Fellow to the Royal Society of London.

               In 1917 Ramanujan got tuberculosis and so he returned to India. He died at Chelput in Madras on 26th April, 1920. 

Who was Pythagorus?

               In the study of elementary Geometry we all are familiar with the concept of “Pythagorean Theorem”. This tells us that for any right angled triangle, the square of the longest side of the triangle (hypotenuse) is equal to the sum of the squares of the lengths of the other two sides.

               But do you know who invented this famous formula that still is the basic concept of the geometrical studies on triangles? He was Pythagorus, the Greek philosopher, mathematician and astronomer. Pythagorus was born during 500 B.C. in Samas, Greece, near the present city Metaponto in Italy. He migrated to South Italy during 532 B.C. to escape the tyrannical rules those prevailed there.

               But his inquisitive and probing mind always thrived him to share his ideas and thinkings among the people. These desires ultimately led him to establish an Academy at Carton — presently known as Crotona to achieve his goals. His teachings on ethics, politics and brotherhood had a great effect over the people there. His thoughts and ideas were flourished throughout most parts of Italy and Greece. But all these eventually died out towards the end of 4th century B.C., largely because of opposition from some quarters for some reason or other. But apart from his philosophical thinkings, his contribution is also credited with the mathematical concepts of the functional significance of numbers. He, in fact contributed to the development of mathematics and geometry in addition to his ideas on Western philosophy. It is an established fact that his ideas greatly influenced the thinking of Plato and Aristotle.

               In the scientific world, his theories on geometry, mathematics, astronomy, sound behaviours etc. were gratefully acknowledged. The famous astronomer, Copernicus for instance, described Pythagorus as a fore-runner of the suggestions put forward by him that earth and other planets rotate in orbit around the Sun.

               During 493, B.C. Pythagorus died at the age of 83.