Chandigarh, Thursday, September 16, 1999
Chandigarh, Thursday, September 16, 1999 |
Diamonds in the sky by Nataraja Sarma “AS she lay dying, she scattered all her diamonds and other riches to the worlds,” — that sounds like an extract from a fairy story but it happens to be true in our universe. 100 years of zero
expansion materials Threat
from computer crimes Science
Quiz
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Diamonds in the sky “AS she lay dying, she scattered all her diamonds and other riches to the worlds,” — that sounds like an extract from a fairy story but it happens to be true in our universe. A star called IRAS 16594-4656 has been dying slowly over the last thousand years or more, and in her death throes, she has been throwing out vast amount of material. The star is now surrounded by a saintly halo of dust hundreds of times larger than our solar systems. Astronomers label such a configuration as a proto-planetary nebula. The dust is very cold, at almost the temperature of outer space and so cannot be seen by optical of infrared telescopes easily. However, the European Space Agency’s infrared space telescope, Infrared Space Observatory (ISO), has detected, in the dust surrounding a star, the chemical signature of a mysterious compound made of carbon, whose nature is being actively debated by astronomers all over the world. The European Space Agency (ESA), though not as large as the American NASA, has provided the scientific world some rather unique information on the space round us. In November, 1995, an Ariane rocket from French Guyana launched the infrared space telescope with spectrometers into orbit to measure infrared radiation at long and short wavelengths. During the two and a half years of its operational life, the ISO gathered some 30,000 pieces of data which are still being analysed. This unique space platform for infrared astronomy was able to examine cool and hidden places in the universe. About ten years ago, the space physics group at the University of Calgary, USA, detected carbonaceous compounds, for the first time, with the early infrared satellite IRAS. Very recently, a Spanish group of scientist used the short wavelength and long wavelength spectrometers on board the ISO to detect a broad infrared emission band around the wavelength of 21 microns, a band characteristic of diamond or a similar carbon compound. So far 12 stars have been found to produce compounds with this spectrum, but IRAS 16594-4656 seems to give a very strong signal at this wavelength. The ISO has gathered data on these dying stars with greater resolution than was obtained hitherto. It has been known for a long time that stars, our sun included, are giant thermonuclear furnaces inside which lighter elements are converted to heavier and more stable ones, generating vast amounts of energy in the process. This enormous energy is thrown out in the form of radiation, gamma rays, light (without which we cannot live!), as well as atomic particles. At the periphery of these furnaces, where heavier elements are present, the star becomes a huge chemical factory that churns out compounds of these elements. These compounds would normally be sucked back into the thermonuclear blaze, but when the star is dying and the inner temperature falls rapidly, the internal pressure may drive peripheral dust out into space. Carbon compounds in space have interested astronomers for many years, as it might provide some indication of extra-terrestrial life. It was while looking for such compounds that tiny crystals of carbon were detected from their infrared emissions. Teams of astronomers and chemists are now looking at carbon compounds that give the same signatures as those detected by the ISO. Some scientists believe that they could be molecules of 60 carbon atoms linked to form a sphere, the so-called fullerenes. Though great efforts have been made to detect them in extra-terrestrial debris, they have never been found in space. Other scientists suggest that these carbon crystals could be diamonds — as the Beatles sang, “Lucy in the sky with diamonds”! Small diamonds have been found in meteorites and they are thought to have been formed even before the solar system came into existence. This strengthens the suggestion that diamonds are made by dying stars. A group at the Institute d’ Astrophysique Spatiale in Paris did separate very tiny diamond crystals from a piece of the Orgueil meteorite and measured its infrared absorption. The results matched the data of the ISO very closely, leading to the inference that there are diamonds floating around in the universe. Both fullerenes and diamonds are much more common than one would suppose. Fullerenes are detected in the combustion of carbon-based gases, such as methane. The first method of making fullerenes was to vaporise carbon by high power pulsed laser. A much simpler way is to strike an arc between two carbon electrodes in an atmosphere of helium. The fullerene is then extracted with toluene and purified by chromatographic techniques. Fullerenes are being investigated as “capsules” to deliver new curative drugs to the human body. They can also be fashioned into extremely fine tubes — nanotubes — for filtration and other applications. The synthesis of diamonds has now advanced to become an industrial process. The common technique is to subject carbon compounds to high pressure and temperatures of over 3000 degrees Celsius to get industrial quality diamonds of upto 25-milligram weight. A cheaper alternative, but as yet to be developed, is the chemical vapour deposition (CVD) technique. First reported in 1911, the method decomposes a hydrocarbon gas like acetylene or methane on to a heated substrate or surface. If the conditions are suitable, small diamond crystals grow on the surface. Four decomposition techniques are popular. The gas could be mixed with hydrogen and directed towards a filament heated to 2200 degrees Celsius. A cold alternative is to create a glow discharge by a high voltage, radio frequency or microwave oscillator. Laser beams can also break up the hydrocarbon gas, but the simplest method is to direct an oxyacetylene flame on the substrate. But if they are formed in the dust surrounding some stars, at relatively low temperatures and conditions of low pressure, there must be easier ways to synthesise them. The exceedingly low
pressure in outer space and the streams of carbonaceous
compounds present may be conducive to the formation of
fullerenes or diamonds. It, therefore, comes as no
surprise that traces of diamonds and other carbon
compounds are present in the outer space. (PTI) |
100 years of zero expansion
materials Most solids increase in size when their temperature is increased. Change in size is small and is denoted by thermal expansion coefficient which for a long rod of a material is the change in length for a rod of unit length per degree increase in temperature. Otherwise a change in volume for a unit volume of the material for each degree rise in temperature is an equally good measure of thermal expansion. For most materials thermal expansion coefficient is around 10-5 per degree rise in temperature. It means that if the temperature of a one kilometre long rod increase by one degree its length increases by one centimetre. Although it is a small change yet it can have serious repercussions in some situations. For example, a small gap is left in between different segments of a railway line to allow for thermal expansion in summer. Fish plates are used to secure fast different segments at the gap. In the year 1897 Swiss scientist Charles Guillaume discovered that an alloy (a uniform mixture of two or more metals obtained by melting) of 65% iron and 35% nickel exhibits zero thermal expansion upon heating. Moreover, this special property of zero thermal expansion is displayed over a wide temperature range. A number of other similar alloys show this characteristic behaviour. Family of alloys which exhibits the behaviour of invariable size when heated is called Invar alloys. Invar is simply the first five letters of the word invariable. Invar alloys display magnetic behaviour also. Magnetic behaviour disappears at high temperature of a few hundred degrees Centigrade. Incidentally, zero thermal expansion characteristic disappears with Invar alloy becoming nonmagnetic at elevated temperature. Discovery of Invar alloys fetched Charles Guillaume Nobel Prize in Physics in 1920. There have been a number of attempts to understand the strange but interesting behaviour of Invar alloys over the last 100 years but a satisfactory answer eluded the scientists for a full century. However, the picture has become clearer in 1999. A member of Invar family is Elinvar coined from the words Elastically Invariable. This is an alloy of iron with 36% nickel and 5% chromium. Elinvar shows temperature independent elasticity. Elasticity in simple words is what gives a spring its spring action. Elinvar has been used to make springs for mechanical watches which needed winding to make it run. Electronic watches with a cell have pushed the mechanical watches into the background. Associated with Invar effect is the anti-Invar effect in which an exceptionally large thermal expansion is observed. Anti-Invar material are still in their infancy. Invar alloys find applications in temperature sensitive devices such as surveying tapes and most notably for fabricating shadow masks in TV and computer screens. Image formation in TV and computer screens occurs when an electron beam strike the dots of a phospor material, which emit light when struck by electrons, coated on the screen. The shadow mask prevents the outer edges of the electron beam from hitting the wrong phosphor dot. The shadow mask gets heated and if the mask material is not zero expansion material there would be loss of picture quality. After a century of a variety of applications but not much understanding of the basic phenomenon a team of scientists from the USA and Sweden has come up with a feasible explanation for the special behaviour of Invar alloys. Invar effect has been linked with the magnetic behaviour of these alloys. Magnetic behaviour is due to the magnetism associated with atoms is iron and nickel. Magnetic atoms arrange themselves in such a manner that their magnetism points in a particular direction. With increase in temperature ordered arrangement of magnetic atoms is disturbed and it becomes a bit random. A key feature of the Invar alloys that was not realised earlier is that the ordered arrangement is possible for slightly larger volume and random alignment occurs at smaller volume. With increase in temperature normal expansion of the atomic structure takes place but the expansion is compensated by the decrease in volume arising from the randomisation of the atomic magnets. For the compensation to take place the atomic arrangement has to be such a state in which slight movement of atoms is possible. Here the concentration of Invar alloys comes into the pictures. Iron alloys with around 35% concentration of other atoms have inherent instability in the structure which makes the readjustment easy without much fuss. This new understanding of the phenomenon should make it possible to develop more alloys in the Invar family and that should lead to more practical applications. The writer is
Professor, Physics Department, Punjabi University,
Patiala. |
Threat from computer crimes COMPUTER crimes are fast becoming a serious threat to the corporate community across the globe. Computers have become part and parcel of every one’s life. Computerisation has showered immense benefits but is fraught with several risks, which include computer crimes. Computer crimes, not easy to define, broadly refer to those committed either on a computer system or with the aid of such system. Technical differences exist among computer crime, computer related crime and computer abuse, but their basic characteristics are, more or less, similar. The number of computer crimes in the last six years has been increasing and is showing an annual growth rate nearing 100 per cent, according to a study conducted by National Centre for Research in Computer Crimes (NCRCC). With the advent of technology, it has become harder for the computer illiterate to work efficiently and easier for the wizards to carry on the destructive work. Some of the crimes were investigated successfully. But, in many cases, it was not able to pinpoint the criminal due to lack of provision in design of system, of audit trails, of logs, of security consideration, of password protection, etc. Crimes committed with the aid of technology in banks and other organisations, range from mere vengeful attitudes to avarice. Computer crimes impose heavy financial losses on the affected organisation. In a survey conducted by the American Bar Association, 72 respondents stated that their estimated annual losses ranged from $124 million to $ 730 million due to computer crimes. An estimate by the Businessweek put the total amount involved in computer related crimes in the banking industry at $3.5 billion. Besides, implicit losses include loss of goodwill, competitive disadvantage due to adverse publicity etc. The impact of computer crimes on an organisation extends beyond financial losses. It also results in leakage of sensitive data to rival organisations, complete shutdown of the operating systems, including the communication channels, corruption of the programmes and databases, and blackmailing and spying. Computer crimes are described as “Silent Crimes”, as these can be committed without anyone being aware of it, with the criminal, many a time, operating from areas far from the crime scene, without making any sound or noise or visible activity as in a conventional crime. Secondly, computer crimes are often transactional in character, thanks to the tremendous technological facilities. Thirdly, relative to the conventional crimes, computer crimes are easier to commit, but harder to detect and prove, due to the lack of skill among the crime-detecting agencies and the inadequacies in the existing legal system. One of the most important characteristics of the computer crimes is that many times these are not reported by the affected organisations for the fear of loss of reputation. According to an international report, only 5 per cent of the losses caused by computer crimes were reported. Around 150 crimes were reported by the end of December, 1998. In India, the incidence of computer crimes is low, mainly because the country started late on computerisation and the level of computer penetration is still low. However, the use of computers is expected to soar in the next decade, particularly in banking and financial sectors. The Government’s IT vision envisages a revolution in computerisation by 2010. The directive recently issued by the Central Vigilance Commission (CVC) to banks wants the latter to computerise 70 per cent of banking business by January, 2001. The CVC has also desired that the listed companies compulsorily offer the electronic clearing services to their customers for payment of dividend and interest warrants. Demat of shares, debentures and bonds is on rise and transactions of the government securities is expected to be done through On-line Real Time Gross Settlement. Over and above these imperatives, the banks, in their own interest, have to increasingly computerise their operations if they want to survive in the competitive business environment for long. The RBI has been making constant efforts to make the banks aware of this lurking phenomenon. In order to prevent computer crimes, the RBI has laid down specific norms for each activity area involving computers. Besides, the RBI is emphasising on development of the skill levels of the banks personnel. It has issued guidelines to banks on the maintenance of minimum records in computerised environment so that subsequent investigations are not hampered by the lack of understanding or lack of access to computer data. Even in other countries, in spite of the introduction of computers in banks long ago, there has been little effort to give it support, Numerous difficulties related to the safety, security, liability, protection, compensation etc, are left to themselves, creating an atmosphere of uncertainty. The banking acts deal only with routine matters of banks. In USA, there are many cases before the Supreme Court which have been filed by data processing service bureau industry, challenging banks on the rights of offering computer services. If this continues, the litigation will be the main bottleneck in the process of computerisation of banks. In one survey, the following reasons were reported for financial losses caused by abnormal computer incidents: ignorance/negligence (50%), dishonest (15%), sabotage by internal people (15%) and theft/damage by outsider (5%). This clearly reveals that most of the financial losses i.e. 80 per cent are caused internally. All banks should
recognise the potential threat of computer frauds and
crimes, and focus on their prevention, so that the future
of computerisation becomes safe and sound. The government
should come out with laws to handle computer crimes
expeditiously. |
Science Quiz 1. “On Mondays, Wednesdays and Fridays we use a wave theory of light and on the other three days, the corpuscular theory of light”, said a great scientist about the wave-particle nature of light. Who proposed these two theories for the first time? 2. A scientist of IIT, Kanpur, has recently developed a supermagnetic material soluble in water, which can be very useful for manufacturing magnetic floppy discs, radio cassettes and other electronic components. Can you tell the name of the newly developed molecules of which this material is made? 3. ABMS is a system to detect, identify, intercept and destroy in flight the warheads of missiles. What is the complete name of this system? 4. Researchers have identified a group of genes that determine the exact location and proportion of body parts like hands, eyes, heart, legs etc. that develop on an embryo in the mother’s womb. What is the name of this group of genes? 5. In which unit is the blood pressure in human body measured? What is the maximum and minimum value of this pressure in a healthy young human being? Which instrument is used to measure this pressure? 6. What are the plants called that grow in desert and semi-desert regions and can survive without water for long periods? 7. Which is the most stable nucleus? Which one is the least stable? 8. As the lower part of the atmosphere — the troposphere — warms due to greenhouse effect, the upper parts of the atmosphere cool. What is this overall effect called? 9. What is the process of melting of ice under pressure and then its refreezing on removal of this pressure called? 10.
Which effect does this limerick convey? Answers 1. Dutch scientist
Christian Huygens and British physicist and mathematician
Isaac Newton 2. Kelplerate molecules 3. Anti-ballistic
missile system 4. Homeotic selector genes 5. Millimetres
of mercury column; 120 and 80 mm Hg; sphygmomanometer 6.
Xerophytes 7. Iron neucleus; deuterium nucleus 8.
Radiative cooling or temperature inversion 9. Regelation
10. Contraction of the length of an object when it moves
with a speed comparable to the speed of light. |
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Net 4 India to
serve Delhi The company, which is part of the UK based Sawhney group of companies, will provide a number of value added services to the user giving end-to-end solutions. The services will include Internet access, e-mail, web hosting, e-commerce, web design, web strategy consulting and Internet marketing. Net4 India will be offering assistance in strategising, consultancy, database distribution management and customer services. Iomega’s
Zip drive Its QuikSync software can automatically save a designated file or folder interrupting user’s work. Copy Machine makes multiple copies of Zip or Jaz disks using one or more drives. It is a great way to share files and ensure there is a backup disk for important information. The password protection feature in IomegaWare software ensures privacy of one’s confidential files. With Norton Zip Rescue (NZR), common system problems such as damaged system files, Windows 95 and 98 registry corruption can be resolved easily. Motorola MCG is
now ON Semiconductor TCS’s
hat-trick achievement The CMM Level 5 achievement is the preserve of just a handful of organisations worldwide. The TCS-SEEPZ Centre is now the third delivery centre in TCS to have achieved this distinction after the TCS-US West Centre and the TCS-HP Centre. Datapro in
hardware training arena PTC partnership
with Rolta India PTC has been ranked as the world number one company in CAD/CAM/CAE by International Data Corporation. Rolta India is the country’s leading CAD/CAM/GIS solution provider and a leading IT service/software exporter. —R.
Suryamurthy and Gaurav Choudhury |
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