Current S & T Terminology- 1 | Science & Technology for UPSC CSE PDF Download

Allotropy 

The property of some elements to exist in two or more different forms is called allotropy. Elements like carbon, oxygen, sulphur and tin show this property. Allotropes of carbon are diamond and graphite while that of oxygen are oxygen and ozone.

Alloy 

Alloy is a metal prepared by mixing two or more metals/non-metals to obtain desired properties. Examples of alloys are steel, brass, bronze etc.

Aminocentesis

Aminocentesis in a diagnostic technique used for detecting genetic defects in the unborn babies. This test is carried in about the 16th week of pregnancy when enough amniotic fluid, which surrounds the foetus inside the womb, is present. So that the test can be done and if required, in case of presence of some genetic defect, the pregnancy can be terminated without much complications. The test involves taking a sample of amniotic fluid from the expectant mother's abdomen using a needle. The fluid so obtained consists of cells of developing baby which, then examined for the presence of absence or genetic disorders. This test can also reveal the sex of the baby.

Antibiotics

Antibiotics are a group of organic compounds secreted by fungi which are antagonistic to other organisms like bacteria and therefore used in treating many bacterial infections. The first natural antibiotic discovered was penicillin. Other examples are streptomycin, chloromycin etc. Antibiotics are also being produced synthetically.

Antibodies

Antibodies are a group of specific proteins produced inside the bodies of mammals to defend themselves from foreign organisms or chemicals.

Antigen

Antigen is a foreign molecular entity which induces production of specific antibodies against it.

Antiseptic

Antiseptic is a substance used on a living surface (e.g. skin) to destroy micro-organisms and sterilise it. Ethyl and isopropyl alcohol, diluted 70% with sterilise water, iodine (dissolved with potassium iodide in 90% ethanol) are some examples used as antiseptic.

Aqua regia

It is a mixture of one part of concentrated nitric acid and three parts of hydrochloric acid and is so powerful solvent that it dissolves all metals including noble metals like gold that do not dissolve in any other acids.

Artificial intelligence 

Artificial intelligence is the technology of constructing a machine which can actually think like human beings in all aspects. It includes all such machines which can recognise and respond to sound and voice, and also learn to undo the mistakes committed by man without the interference of an operator. Such machines also called Ultra Intelligent Machines (UIM) do not exist yet.

Asteroids

Asteroids are small rock like bodies that evolve around the sun between the orbits of Mars and Jupiter at a distance of 450 million kilometres from the sun. Ceres, the largest asteroid, has a diameter of about 1000km while the smallest asteroid may be only a kilometre across.

Atomic clock

Atomic clock is a device used to make precise measurement of time. These clocks use vibration of atoms or molecules to measure time, instead of quartz crystals or a coiled spring which are used in quartz and  mechanical watches respectively. Atomic clocks commonly use rubidium atoms, caesium atoms, hydrogen atoms and molecules of ammonia gas. These clocks, which gain or lose no more than a second in 200,000 years, are used to keep time in laboratories and observatories.

Aurora 

Aurora refers to the intense and colourful light emitted by the earth's upper atmosphere mostly visible in polar regions during winters. Aurora borealis of 'northern lights' is seen in arctic region whereas the aurora baustralis of the 'southern lights' is seen in the antarctic or southern latitudes.

Awacs

An acronym for Airborne Warning And Control System, it is an electronic system that is used for detecting both low flying and high flying enemy aircrafts using radar mounted on a surveillance aircraft.

Bakelite 

Bakelite is a thermosetting plastic which once set cannot be melted by heating. As it is resistant to chemicals, electricity and heat, it is used as an insulator in electrical fittings and in the handles of cooking utensils.

Biodiversity

Biodiversity is the variety and variability of all living forms on earth. In simple words, it is the sum total of all living plants, animals and microbes. Biodiversity is essential as mankind is dependent on other species for the sustenance of the biosphere and the supply of basic necessities, especially food. There is a growing concern about the biodiversity because a large number of species are extinct or facing extinction. There are about 5 to 30 million living species, of these only 1.4 million have been described. Whereas, the species extinction rates are approximately 10,000 to 20,000 per year. The warm tropical regions are the richest habitat of biodiversity.

Conservation of biodiversity is of utmost importance to humans because plants and animals provide us many known and unknown economic and essential services like cures for diseases and genes to increase the yield of our food corps.

Biological clock

Biological clock, in its widest sense, is any form of in-built time keeping system found in all living organisms. It times the various activities of the organisms with the regular changes in their surroundings, such as day-night cycle. The cycle of sleep, wakefulness and many other body activities repeats over a period of approximately 24 hours and hence also known as the circadian rhythm. Biological clock is mostly associated with the rhythms relating to environmental cycles like day and night, lunar months and seasons of the year. There can be cycles of more than 24 hours duration too. Human beings have a daily, weekly, monthly and yearly biological rhythms. The level of hormones and other chemicals in blood varies over each of these periods.

Bioluminescence

Bioluminescence in the emission of light without the production of any heat by 'photogenic' living organisms like fire flies, many  deep-sea living fishes, certain worms and some algae. The light is emitted due to a chemical reaction similar to respiration. The compound generally responsible for the bioluminescence in most organisms in luciferin, which is oxidised with the aid of the enzyme Lucifers.

Biopsy

Biopsy is a diagnostic procedure which involves taking tissues from the affected part (s), usually some unusual growth or lining of an organ for microscopic examination. A hollow needle is liver or kidney. The tissue so obtained is then examined under the microscope to know whether the tissue is benign (non-cancerous) or malignant (cancerous).

Biotech food

Biotechnology, which refers to the development of techniques for the application of biological processes to the production of materials for use in medicine and industry, has even entered the field of food processing. The first commercially available product, tomato puree has been developed by a biotechnology team, using a specially researched slow-ripening tomato. This tomato puree is the first product to gain approval for food use in both the UK and the US.

British scientists have also made the world's first beer using gene technology. This beer, a low calorie product, contains about one percent more alcohol (by volume) than beer made with unmodified yeast. Produced by the Brewing Research Foundation International, it uses a genetically modified (GM) brewer's yeast that carries an extra gene that helps in breakdown of the large sugar molecules that natural yeasts cannot degrade, releasing glucose that the yeast ferments into alcohol.

A GM food product that gained first approval anywhere in the world was particular baker's yeast that was approved for food use in the UK in 1990. This yeast produces carbon dioxide more quickly than conventional baker's yeast.

Black hole

A black hole is a fascinating and mysterious astronomical body possessing a gravitational field so intense that no matter or radiation can escape from it. These are believed to form as a result of the gravitational collapse of a star after it has used up all its nuclear fuel (all stars have a life cycle- they are born, grow old and finally die).

Smaller stars create supernova explosions when they die, leaving neutron stars; it is the more massive stars that are believed to create black holes.

The problem of detecting black holes is that, being unable to emit or reflect radiation, they are invisible. However, astronomers locate black holes by the gravitational and other effects they have on nearby stars.

By-pass surgery

By-pass surgery is a method of treating blocked coronary arteries which impair functioning of the heart. Coronary arteries supply blood to the heart muscles. When these arteries narrow or are completely blocked due to deposition of fatty substances, the blood supply to a particular part of the heart is reduced or cut off resulting into severe chest pain in the patient who may even collapse. This condition is treated by providing alternate path for blood supply by-passing the blocked artery using a piece of vein taken from the patient's own leg.

Cable television

Cable television refers to transmission of image and sound simultaneously to television set through cables instead of through high frequency radiowaves. Television signals transmitted by telecasting stations are high frequency waves and can be received properly only if the receiving antenna is in direct line of sight of the transmitter. However, at far of places the TV signals received are weak and are sometimes blocked by tall buildings and similar structures and hence clear signals are not received by the TV sets. This situation can be solved using cable TV, which enable many TV sets to simultaneously receive signals from a single antenna located at a suitable place. Signals from the antenna are amplified and distributed to TV sets through a network of cables. Signals from satellites can also be received by large dish-antenna and distributed through cable. Through cable TV each TV set gets sufficiently strong signals to produce a clear image.

CAD and CAM

CAD is an acronym for 'Computer Aided Design' and CAM for 'Computer Aided Manufacture'. Both are computer that are used to create drawings or to assist in manufacture of goods. CAD programs are usually used for designing printed circuit boards and computer chips. CAM programs are usually used in the manufacture of goods in industries such as computer-driven lathes, drills, welding machine or robotically operated production line are employed in factories to speedily manufacture a wide range of precision products.

CAT scan

CAT or Computerised Axial Tomography scan or CT scan is a diagnostic method of taking X-ray pictures of thin slices of the body without even piercing the body. It is used for vessels in soft tissues such as brain of in large organs such as the liver which is not possible using Xray techniques.

During CAT scan the part of the body to be scanned is placed inside a ring, which has an X-ray gun at one side and a detector on the opposite side. The X-ray beam from the gun after passing through the body is received by the detector which is connected to a computer that processes all the inputs into a flat picture.

Catalytic convertor

Catalytic convertor is a device installed in petrol-driven automobile's exhaust system to turn the environmentally damaging emissions into harmless  products. The exhaust fumes of petrol-driven automobiles using unleaded petrol contain gases like carbon monoxide, nitrogen oxides and hydrocarbons like benzene which are harmful to health when inhaled. The catalytic convertor contains a catalyst which in most cases is a blend of the noble metals platinum, palladium and rhodium. As the exhaust gases pass through the convector, the analyst oxidizes carbon monoxide and hydrocarbons and  reduces nitrogen oxides to harmless substances such as carbon dioxide, water and nitrogen. The convertor cannot be used in automobiles using leaded petrol because the noble metals used as catalyst in the convertor are sensitive to lead and are rendered inactive as lead deposits on them.

Cholesterol

Cholesterol, a complex waxy fat-like substance, is found as well as synthesised in all animal tissues and cell though in varying degrees. It is an essential structural ingredient of all biological membranes, vital for cell functioning and serves as a precursor for bile salts, steroid hormones and vitamin A but harmful when in excess. It is one of the   main causes for narrowing of arteries which may cause heart attacks. Pure cholesterol is solid at room temperature and is insoluble in water. An adult human has in total about 60 gm of cholesterol and about one gram of which is used up every day. The lost cholesterol is made up in the liver. Cholesterol, whether ingested directly or synthesised in liver, has to be transported to every nook and corner of the body through the blood stream. It is transported as minute complexed particles tagged to plasma proteins. Such complexes are called lipoproteins.
They occur in several forms of which two are very important- high density lipoproteins (HDL) having more protein than fat and low density protein (LDL) having more fat than protein. LDL moiety serves as a carrier of cholesterol through the blood stream, dripping it off where it is needed for metabolisation and cell building. Since LDL is a carrier of cholesterol in the system, it is commonly called 'bad cholesterol' as against HDL moiety which packs up the unused cholesterol from here, there and every where and brings it back through blood stream to the liver for reprocessing/ neutralisation or excretion in bile and hence called  'good cholesterol

There is a positive statistical correlation  between the incidence of coronary heart disease and low levels of HDL and also high levels of LDL and total cholesterol. Moderate  levels of LDL in blood are essential for health but many of us have levels well excess of those required. Greater the level of LDL in blood, the greater the rate at which cholesterol is deposited on the walls of arteries thus favouring atherosclerosis- an arterial lesion characterised by intimal thickening due to accumulation of cholesterol and other substances leading to overall hardening of arteries- which increases blood pressure and causes heart attacks and strokes. When LDL component in blood is excessive, the levels of cholesterol or another blood fat, triglycerides, or both become abnormally high.

The more HDL in blood, the less is the risk of heart attacks perhaps because this component reduces the tendency the cholesterol to stick to the inner walls of the arteries. LDL moiety is more readily oxidised in blood stream which facilitates artery blocking plaques or atheromas

Comet

Comet is a celestial body made up of ice and dust. The heat of the sun evaporates the ice producing the long tail when a comet nears the sun. Comets usually have highly elongated orbits. The most famous comet is the Halley's comet seen every 76 years. It was last sighted in 1985-86. Another example is Hale Bopp comet.

Compact disc

Compact disc (CD) is an electromagnetic system of recording or storing of digital audio or video information using laser on a aluminium metal disc. The input and output of data, stored in the form of pits and lands, is done using laser beam which scans the rotating disc much like the replaying of phonograph recorder. The music from an studio CD does not have any distortion or noise and have virtually replaced phonograph records. The CD can also be used to store and record text, pictures and sound simultaneously on a single disc. CD have large storage capacity- the entire text of and picture of 30- volume Encyclopedia Britannica can be stored on a single CD, CD, which are versatile, adaptable and have large storage capacity, are finding wide applications in entertainment, book publishing, and other areas involving use of computer systems.