My Science School

Sushruta, who lived in the 7th century BC, was an ancient Indian surgeon who was famous for his pioneering operations and techniques. His book the’ Sushruta Samhita’, is an advanced collection of the surgical, as well as information on other specialties, geriatrics, diseases of the ear, nose, throat and eye, toxicology, aphrodisiacs and psychiatry.

   Examples of some of Sushruta’s groundbreaking operations include rhinoplasty which involves repairing or restructuring the nose, removal of a dead foetus, and surgical removal of stones in organs like the urinary bladder.

      Sushruta used wine to dull the pain during operations. He encouraged his students to practice surgical techniques by operating on objects like watermelons and reeds.

    Sushruta took surgery in ancient India to admirable heights and because of his numerous contributions to the science and art surgery in India; he is regarded as the ‘father of surgery’ and ‘father of plastic surgery’.

Stephen Hawking, theoretical physicist and cosmologist, is remarkable in many ways. Despite challenging physical impairments, he has contributed hugely to he world of science.

   Hawking suffers from a type of motor neuron disease that has left him almost completely Paralyzed. This did not stop him from working on the subject of black holes and providing theories for their behavior, including the idea that they emit radiation.

    Hawking believed black holes to be celestial death traps that swallowed up all energy. However, he determined there was room for this phenomenon, through the merging of quantum theory, general relativity and thermodynamics, distilling it all into one path breaking formula in 1974.

      Hawking wanted to write a book about the mysteries of the universe that would connect with the public. This task seemed impossible after he lost the abilities to write and speak. But Hawking did not give up, and his vision was finally realized when finally realized when his ‘A Brief History of Time’ became a best-seller. 

James Watson, an American molecular biologist, geneticist, and zoologist shared the 1962 Nobel Prize in Physiology or Medicine for discovering the structure of DNA in 1953. He gained worldwide fame and prominence as the joint author of the scientific papers between 1953 and 1954 which he co-wrote with fellow scientist Francis Crick. Their work laid down the double helical structure of deoxyribonucleic acid, or DNA.

    The DNA molecule is a mega molecule that is the process of genetic  replication. One of the most celebrated science writers, Watson published his textbook ‘Molecular Biology of the Gene’ in 1965 and his best-selling autobiographical book ‘The Double Helix,’ in 1968.

    Watson helped to establish and direct the Human Genome Project at the National Institute of Health, where he oversaw the mapping of the genes in human chromosomes. His own genome was sequenced in 2007, making him the second person to have this done.

Richard Feynman was an American Scientist who is considered to be one of the greatest and most influential theoretical physicists in history.

  Feynman revolutionized the field of quantum mechanics and formulated te theory of quantum electrodynamics.

  Feynman is responsible for the introduction of fundamental computational techniques and notations into physics. The Feynman diagrams have dramatically changed the way in which basic physical processes are conceptualized and calculated. He also studied the physics of super cooled liquids. In order to increase the understanding of physics among the general public,

   Feynman wrote two important books- ‘The Character of Physical Law’ and “Q.E.D: The Strange Theory of Light and Matter’. He was awarded the 1965 Nobel Prize in Physics for successfully resolving problems related to the theory of quantum electrodynamics.

A black hole is a fascinating and mysterious astronomical body. It is so-called because it gives off no light and sucks in whatever matter and energy that comes near it. It is the end product left behind after the death of a very massive star.

All stars have a life-cycle — they are born, grow old and finally die. The way they end up depends on the mass they start with. If the star is very massive — more than 30 times as massive as the sun, the end comes in a blinding explosion known as supernova. After the explosion what is left behind is a tiny object called black hole. The gravitational field on a black hole is so strong that it does not allow even light to escape. Thus, a black hole cannot be seen. However, astronomers locate black holes by the gravitational and other effects they have on nearby stars.

The biological clock is an in-built timing system found in all living organisms. It times the various activities of the organisms and keeps them in harmony with the regular changes in their surroundings, such as the day-night cycle. The cycle of sleep, wakefulness and many other body activities repeats over a period of roughly 24 hours. That is why it is also known as the circadian rhythm. It works by keeping track of the rhythmic changes in the environment such as day and night, movement of ocean tides, phases of the moon, and seasons of the year. These rhythms can be shifted and the biological clock can be reset by changing, for example, the temperature at which a plant is grown or the duration of light exposure an animal gets.

There can be cycles of more than 24-hour duration too. Human beings have daily, weekly, monthly and yearly biological rhythms. The level of hormones and other chemicals in blood varies over each of these periods.

One of the effects of the biological clock is jet lag felt while travelling long distances by air.

 

Atomic clock is a device for measuring time. It makes precise measurements of time. It makes use of the vibration of atoms or molecules, instead of quartz crystals or a coiled spring which are used in quartz and mechanical watches respectively, to measure time.

The most commonly used atoms and molecules in atomic clocks include caesium atoms, hydrogen atoms and molecules of ammonia gas. Atomic clocks based on rubidium atoms instead of caesium are now in use. Some atomic clocks gain or lose no more than a second in 200,000 years. These are used to keep time in laboratories and observatories. 

It is a diagnostic technique to check for genetic abnormalities in unborn babies. The test involves taking a sample of the amniotic fluid which surrounds the growing baby inside the womb. It is usually done about the 16th week of pregnancy as by this stage there is enough amniotic fluid to allow the test to be carried out and enough time to terminate the pregnancy in case genetic abnormalities are detected. This can help prevent later suffering of the baby and the family.

For obtaining a sample a hollow needle is carefully inserted under local anaesthesia through the expectant mother’s abdomen. The amount of fluid withdrawn is only about 20 ml. This fluid contains cells from the developing baby. Chemical and microscopic examinations of these cells can provide invaluable information, revealing the presence or absence of genetic disorders which cannot be detected otherwise.

The chromosome analysis of the cells in the amniotic fluid can also reveal the sex of the baby.

Allergy is a state of hypersensitivity acquired through the exposure to a particular substance, called allergen. Spores, pollen, cat’s hair and proteins of egg, milk, and fish are some common allergens. The most common allergen is the house-dust mite.

Usually only parts of the body which are exposed to allergens show signs of allergy in the form of rashes or weals. However, if an allergen gets into the blood stream, it can cause reactions almost anywhere in the body.

Practically all allergies are caused by an over-reaction of the body’s defence mechanism when white blood cells react with allergens considering them as dangerous infectious organisms, it leads to allergy. Under normal conditions, the white blood cells (lymphocytes) on coming in contact with foreign substances like bacteria, viruses and proteinaceous matter produce what are called antibodies. The antibodies combine with the foreign substance and neutralize it. But when an antibody is formed against a harmless protein it attaches itself to mast cells which contain chemical— histamine. When the particular protein enters the body again, histamine is released. Due to the action of histamine blood capillaries are dilated, their walls become leaky and fluid from the blood comes out in the nearby tissues and they swell. The characteristic redness and itching in an allergy is due to dilation of blood capillaries.

Acquired Immune Deficiency Syndrome (AIDS) is the most devastating and fatal disease of the 21st century. It is a viral disease caused by the Human Immune Deficiency Virus (HIV). What makes it different from other viruses is that, it strikes at the body’s own defence machinery (the immune system) that constantly fights the vast array of microbial enemies invading our bodies. The virus may remain dormant upto 10 years until some event activates it. On awakening, it disarms the immune system. With its main line of defence shattered, the body now falls easy prey to even the common infecting agents that it would otherwise ward off. The patient usually dies of these infections.

            HIV spreads from an infected person to a healthy person through body fluids. Sexual transmission of HIV is most common. Contaminated blood and blood products besides passage of the virus from infected mother to unborn baby are other ways by which the virus spreads.

It is a phenomenon caused by industrial pollution. Natural rain always contains a small amount of dissolved carbon dioxide which makes it slightly acidic. But large-scale burning of coal or oil in industries, power plants and vehicles produce large amounts of gases such as sulphur dioxide, nitrogen oxides, etc., which are released into the atmosphere. These gases rise up with air currents and may be carried by prevailing winds many hundred of kilometres away from their source. Under favourable conditions they react with water vapour and oxygen in the atmosphere to produce sulphuric and nitric acids which eventually come down with rain, snow or fog. Compared to a pH of around 6 for normal rain, acid rains cause considerable damage to vegetation, trees and marine life. As the gases retry and acid rains fall in another damaging its flora and marine life, it has become a cause of concern to all countries. The countries worst affected by acid rains are southern Sweden, Norway, parts of central Europe and eastern regions of North America. Most European countries are therefore making efforts to reduce sulphur emissions by their industries and power plants.

The severity of an earthquake can be measured either by measuring its magnitude or intensity. Magnitude is a measure of the strength of an earthquake at its source. It is assessed on an 8-point scale called the Richter Scale. Devised in 1935, by an American geophysicist, Charles Richter, the scale assigns a number to an earthquake depending on its strength. The Richter magnitude is calculated by using information obtained from a seismograph — the instrument that records an earthquake’s ground motion.

Intensity is a measure of the local effect caused by an earthquake which varies according to distance from the source of the earthquake. The intensity is measured in the Mercalli scale, formulated originally by an Italian seismologist Giuseppe Mercalli. The scale was subsequently modified and is still used as the Modified Mercalli Intensity Scale (MM). It classifies earthquake into 12 categories ranging from 1 (not felt except by few) to 12 (total destruction).

 

Stars take birth out of clouds of hydrogen, helium and dust particles present in galaxies. Due to the turbulent motion in these gas clouds, the dust particles undergo random collisions and condense under the influence of strong gravitational pull. As the gases and dust particles begin condensing, the temperature inside rises due to increasing pressure. As the condensing mass grows bigger the gravitational pressure at the centre increases further till the intense heat raises the temperature to around 10 million degrees Celsius. At this temperature the hydrogen atoms start colliding so vigorously that they fuse with each other to form helium atoms. In the process some mass is lost. For every 1000 kg of hydrogen used up, 993 kg of helium is formed. The rest is converted into tremendous amount of energy according to the relationship E= , where E is the energy, m the mass and c the velocity of light. This energy is liberated in the form of light and heat and a star is born.

The shine of a surface depends on its smoothness. Smoother the surface, more it will reflect light and thus will appear shiny. Unpolished leather does not shine because its surface is full of tiny pores and is rough. When we apply polish on this rough surface, the wax in the polish fills up the very small microscopic pits of the leather surface. Vigorous brushing or rubbing with a soft cloth spreads the wax evenly by melting. This makes the surface shine. If the shoe is rubbed after a few drops of water is sprinkled on it, it shines even more because the cloth surface after absorbing little water does not stick to the wax on the leather surface but glides smoothly. Liquid shoe polishes do not need rubbing as these leave a quick drying film on the leather which itself is reflecting and gives a glossy look. 

Curd is formed by a chemical reaction which involves casein, the protein that occurs in milk. The coagulation of this protein results in the formation of curd. This occurs if bacteria called Lactobacillus acidophilus is present in milk. This bacterium produces lactic acid by the fermentation of the milk sugar lactose. The lactic acid so formed by the bacterial action contains positive hydrogen ions which are attracted to the negative particles of the protein casein. As the latter are neutralized, these protein molecules no longer repel one another but coagulate. The optimum temperature at which Lactobacillus acts is around 40°C. So milk is usually warmed to this temperature before setting it to curdle.