 |
|
| SCIENCE TRIBUNE | Thursday, November 2, 2000, Chandigarh, India |
|
Explosions in the universe
Digital versatile disk Self-aware machines
Science Quiz
|
|
|
Fascinating world of animal communication ON a rainy night, a frog concert fills the darkness. Serene surroundings of the forest echoes with the beautiful song of a nightingale. The eerie howling of a coyote breaks the stillness of the dry and dusty desert. The sounds of the natural world are all around us, evidence of the richness of the animal kingdom. These sounds, which may seem strange humourous or even threatening, may be coded messages from animals. But is there such a thing as animal language? This is a tricky question to answer, even for experts in animal behaviour. Scientist define language as a form of symbolic and creative communication. It is not just a succession of signals aiming for an immediate effect. Unlike humans, animals generally communicate only in three specific situations: to exchange information about source of food, to strengthen the bonds between partners during the mating season or to call help when danger threatens. The chief characteristic of animal communication system is that every signal corresponds to only one message and vice-versa. Every animal species communicates in its own way. However, all animal communication can be classified into five categories. 1. Acoustic message, such as singing, shouting, ultra- or infra sound calls. 2. Optical signals, such as pattern of fur, colour change or sign-language. 3. Emission of odours via chemical substances, such as pheromones. 4. Touch stimulus, as used by chicks to beg food from their parents. 5. Electrical signals, such as those sent by some fish species to improve their orientation. Scientists are trying to understand the complex, varied and fascinating system of animal communication. Vibrations are used by many insects, including some cicadas, ants and beetles to attract sexual partners. But the female stink bug’s elaborate courtship song is more then just a come-on call. It also serves as detailed road map, guiding males to an impending tryst. Andrej Cokl, an expert in insect communication at the National Institute of Biology in Ljubljana, Slovenia, reported that this insect has been found for the first time to use vibrations to signal its whereabouts to a potential mate. He believes that thousands of other species might be doing the same thing. It is a mystery exactly how female stink bugs make their enticing love songs. Cokl observed the bugs moving an abdominal plate attached to the thorax by a small membrane in time with the rhythms oscillating through plants. Spiders, crabs and nocturnal scorpions are known to use vibrations to detect prey, while leaf cutter ants have been shown to send vibrations through plants to call others to come and help harvest the most desirable leaves. Many marine animals rely on sound to communicate, especially at night. Fish often have anatomical adaptations both for making their own distinctive sounds and also for receiving them. Their main instrument is usually the gas filled swim bladder, the organ that helps to control buoyancy as they move up and down. A few fish such as catfish and triggerfish beat a spine-like appendage against their body wall, causing the bladder to vibrate and boom like a drum. But most fish generate sound by contracting muscles attached to the swim bladder. Sound may be of short pulses that last a few milliseconds, or long drawn-out tone lasting several seconds. The pitch can range from a deep 50 hertz rumble at the low end of audio spectrum all the way to a higher frequency squeak around 5 kilo hertz. There are almost as many different sounds as there are calling fish. Some grunt, and others give long, slow hoots, while at least one makes a noise like a foghom. McCouly, a marine biologist from James Cook University in Townsville, concludes that fish songs are intended to communicate something to other fish of the same species. He observed that in ideal conditions individual calls could travel to a distance of two kilometres and fish singing together could be heard as far as eight kilometres. Chorusing could have functions like sharing information on where the best patches of food are and perhaps triggering production of the hormones that control spawning. Members of the animal kingdom can make themselves heard in an amazing variety of ways. One of the most fascinating ranges of sound are the powerful noises-often referred to as songs of the great whales, the travellers of the world’s oceans. The songs of the humpback whales and beluga whales are particularly impressive. These animals can sing for over half an hour without interruption, but what separates them from other species is the great variety of their sounds; a mixture of barking, bowling, humming, squeaking, canary like whistling, rasping, snorting and trilling are continually combined in new ways. In looking at the ways in which birds communicate, researchers have isolated the three levels on which birds identify themselves; the species related level, the regional level and the individual level. The song of the nightingale, for example have several sections, some of them alluring, other warning. Other parts of its songs, however are either individual compositions or imitations of other birds. The nightingale even makes the sounds of other animal species. In some birds like white crowned sparrows, a marked pattern of dialect differences have been found with a change in dialect every mile or two. Researchers believe that dialects help to split populations into local groups which have the potential to respond somewhat independently to changing circumstances such as food supply or climate changes. Some birds such as the sedge wren have evolved to be wandering minstrels, relying on innovations rather than imitations. Males improvise according to the same general rules so that their language is universal and recognised by females everywhere. In other birds, mockingbird has developed such an amazing gift for imitation that it even copies the songs of other species. Scientists believe that here imitation allows the male to increase its repertoire so that he can attract and stimulate females who are impressed by variety and originality. In some animals, communication takes place on such a sophisticated level that researchers have been forced to conclude that language is being used. For example, an amazing type of communication takes place among honeybees. When one of them discovers a source of food, it returns to the hive where it passes this information on to the other worker bees. This is done by means of certain dances, as the Austrian naturalist and zoologist Karl Von Frisch discovered during the 1920s. If the food is located less than 100 metres from the hive, the bee will dance around in a circle to attract attention. The location of more distant food source is conveyed through a waggling dance, in the form of a figure of eight. The speed of the dance indicates the distance of the food and the number of rounds decreases as the distance becomes greater. For example, 40 rounds indicates 100 metres, while 24 rounds means more than 500 metres. The orientation of the dance symbolises the direction of the food, while the dance’s intensity and duration gives information on the richness of the food to be found. Finally, the dancer also reports to its fellow workers about the quality of the food for this they only need to sniff the messenger to recognise the scent of the blossom. The honeybees communication skill ensures that, within about an hour, some 10,000 honeybees can arrive on the site. In ants, chemistry explains how these insects tell each other about food supplies. If one of them finds food, it secrets a pheromone from its abdomen, which then marks the way to the ant. As soon as another ant crosses this path, it will also react in a similar manner. Soon the little scent trails becomes a wide river. Pheromones also enable insects to detect individuals of the same group. These findings are certainly a stride towards unravelling the fascinating and varied communication system of animal world. If humans no longer have a monopoly on the idea on language or dialect, why should animals have a monopoly of language or dialect. The writer is from the department of mycology and plant pathology, Dr Y.S. Parmar University of Horticulture and Forestry,
Nauni, Solan. |
|
Explosions in the universe
LESS than a year ago, an enormous explosion was observed in the sky that astronomers labelled as GRB 971214. Instruments on the Italian-Dutch satellite BeppoSax had earlier spotted a short burst of gamma rays on March 26, 1998, and recorded the position of the source in the sky and relayed the event’s position. This satellite and an instrument on board Compton Gamma Ray Observatory now recorded an intense burst of gamma rays lasting less than a few seconds from an eruption far away in space, about nine billion light years from earth. Physicists found that the energy release in this burst was hundred times more powerful than the energy obtained from extremely bright, rare stars called supernovae. More energy was radiated in those few seconds than what sun radiated in ten billion years. These gamma ray bursts (GRB), phenomenal even by astronomical standard, are the most powerful explosions in the universe and are thought to have come from the formation of black holes during the fiery deaths of supernovae. Such bursts have been observed and they appear to occur randomly several times a day and last only a few seconds to a minute. Only recently most astronomers have agreed that many of them originate in the very distant, early universe. As a result of a burst, a whole spectrum of gamma rays of different energies is emitted. These reach the detectors set up on satellites at slightly different times. The higher-energy gamma rays arrive before the lower-energy rays. A measurement of the time between the arrival of the highest and lowest energy gamma rays can be analysed to gauge the peak brightness and distance of the explosion. The bursts are over so quickly that there is not time to look at its visible glow and so determine its distance by the redshift method initiated by the US astronomer, Edwin Hubble. He noted that the further away a star was, the more its light was shifted to the red end of the visible spectrum. The more distant an object is from earth, the faster it is receding due to the expansion of the universe. Light from this receding object is then ‘‘Doppler shifted’’ towards the red end of the spectrum. Redshift, therefore, became a direct way to estimate astronomical distances. Objects with high redshifted light thus become probes of the early universe because their light has taken billions of years to reach earth. It is not possible to measure the redshift in a gamma ray spectrum and the only solution is to look at the visible afterglow through optical telescopes and so measure the shift of certain characteristic lines. Of the thousands of gamma-ray bursts detected, fewer than 10 have been measured this way. The burst from a exploding source should quickly die down to the brightness of the surrounding glaxy, but observers at W.M. Kech Telescope in Hawaii looking at the GRB 980326 were surprised to get spectral data indicating it had brightened again dramatically, obscuring the surrounding galaxy itself. The colour of the afterglow was blue to start with, but after a month it turned red and led to the conclusion that something else happened at the same place. Various theories have been proposed to explain the origin of such enormous gamma ray bursts, including one that it was
caused by the bursts, including one that it was caused by the exhaust from alien space-ship engines launching into hyper-space! But the energy of the burst was too large even for such an imaginative scenario. Shrinivas Kulkarni, an astronomer at the California Institute of Technology, suggested that this was due to the creation of a supernova by the explosion of a massive star. Two groups from the universities of Amsterdam and Chicago reanalysed the data on some other gamma ray burst and found support for the findings of Kulkarni. Astrophysicists now believe that the explosion was due to two highly dense neutron stars spiralling into each other and annihilating in a tremendous crescendo. According to the astronomers’ theory, a black hole quickly forms in the centre of a dying massive star whose core cannot support itself against gravity. When the star exploded, powerful jets of high-energy particles were ejected into space from a supernova’s central black hole. The satellites saw them as gamma ray bursts only when the jets pointed towards the earth. That makes gamma ray bursts seem like random occurrences at random places in the sky, when in fact they are associated with a particular event. The Compton Gamma Ray Observatory stationed on a dying satellite has now detected mysterious sources that emit a new class of gamma rays. In the universe some 271 objects emit gamma rays but those appear to be located far beyond the Milky Way and emit gamma rays continuously. Now around 170 gamma ray emitting stars are located within our Milky Way galaxy in a region called the Gould Belt. The cause of this continuous emission of energy is not known, but they could be black holes, massive stars, neutron stars and clusters of pulsars. Where the gamma rays come from and how far they have travelled is not known yet, but the data from satellites may pinpoint their point of origin, distance they have travelled and their age. However, an intensive study of the sources could make it possible to determine the geometry of the universe throughout its various epochs, as well as when and where massive stars formed in its very early stages. |
|
Digital versatile disk OPTICAL disk technology has given a tremendous boost to the data storage in computers and programme storage in the video-entertainment. Compact disk (CD) emerged as the powerful secondary storage medium. A computer solution without a CD-ROM drive looks incomplete. Advancements in microprocessor technology, intensive multimedia applications and the enhanced graphical-user interfaces have made the CDs somewhat obsolete. The need for enhanced data transfer rates and the storage has paved the way for a digital versatile disk (DVD) to step in. DVD can store approximately 20 times more data than that can be stored in a CD. The process of compression of data enables the enhanced storage in a DVD. The technique adopted for image compression in a DVD is called the Moving Pictures Experts Group Phase 2 (MPEG-2) technology and that for audio compression is MPEG-3. The finished DVD disk requires a significant amount of time for
reproduction. Efficient construction process enables the DVD to have a thickness which is one half that of a CD. This paves the way for clubbing two disks back to back. A plastic material is taken and a reflective metallic surface is engrossed on to it. For data storage, a single spiral track is made on the surface. The microscopic pits on the surface represent the video and the audio signals. A laser beam present in the drive reads these bits in binary. The difference in the bits 1 and 0 is viewed by the process called Tracking Servo Polarity. The comparative analysis of a DVD and a CD reveals marked performance improvement in a DVD. The conventional VCR shall be made redundant by the DVD video recorder. The day is not far when the consumer shall have an access to a hybrid and a Web enabled
DVD. |
|
Self-aware machines THE importance of having an automated machine or a robot for doing a job instead of a human being is that they are extremely useful in performing routine and repetitive tasks, as they keep going indefinitely and never get bored or careless. Science fiction has always dreamt of such intelligent self-aware machines of future, which could search out their energy source on their own or war machines which can replicate themselves according to need of time, or the machines which can give birth to human babies (artificial hatchery), and even of that times when machine develop so much intelligence that they take over the charge of entire world and treat humans as their slaves. There is no limit to imagination and nothing is impossible in science fiction (so seems to be in real science too). But are such machines possible? According to the first and greatest cybernetic theorist, John Von Neumann, the answer is yes!! At present we can’t foretell how far artificial intelligence might develop in the next 50 years but according to British mathematician I.J. Good’s prediction the intelligent machines were supposed to be doing all the mental activities of human brain by the year 2000. But we know very well that today’s cleverest machine can do no more than chess playing (or a few other activities). The first functional electronic computer ENIAC, of 1946 had 18000 vacuum tubes, could do 5000 calculations per second, demanded high amperage of current, produced a good deal of heat and always kept breaking down. Transistors replaced the tubes and silicon chips replaced the transistor all in less than 25 years and the room-sized computers became palm top computers! From vacuum tubes to microchips the factor of miniaturisation is more than 20 million is to one. Engineers are trying to develop a new-generation of micro-micro chips, which will be shrunk by another order of magnitude. But there is a lower limit beyond which miniaturisation is not possible! The scientists present another idea, the biochips and organic computers — made of protein molecules sandwitched between glass and metal. And hold your breath-the world’s first bionic computer was recently developed by researchers at University of California, Berkley, and it is already in production under the trade name Robocop. Now let’s wait for the complete synthetic brain! Today we only expect computers to assist in our work but the job of future computers will be to hold artificial intelligence rather than doing all the (rubbish) calculations. Alan Turing, one of the leading theorists in area of artificial intelligence and of the belief that machines can become genuinely intelligent, suggested in 1950 that the easiest way to test the machine’s intelligence is to engage a person and the machine in a dialogue session via an electronic display screen. After some time if he begins to mistake the programme for a real person, the programme is said to have passed Turing test of artificial intelligence. American computer expert Kenneth Colby wrote a programme named “Parry” which mimics the responses of a paranoid patient. Another programme designed to conduct therapeutic session was Eliza and still another diagnostic programme was Mycin developed by E.H. Shortliffe. And since then numerous programmes — far more sophisticated than these — have been written. There are programmes (such as game playing programmes) which have the ability to learn and therefore they get better and better with practice and don’t repeat mistakes. Also we are already aware how clever the computer viruses are!! There is a long list of essentials for a machine to hold or develop true artificial intelligence viz., ability to reason, having all sense organs, having a sense of humour, having a sense of emotions etc. In short a good hardware (like a brain) would have to be mixed with a good programme (like its mind). Intelligence, if housed in a humanoid body, would perhaps prove most useful to us ... as we can send them to space on say, a non-return mission, or say they would fight the battles for us. But according to Asimov, robots must always be programmed to obey three laws: (1)A robot may not injure a human and neither allow human being to come to harm. (2) A robot must obey the orders of humans except when they conflict with first law (3) A robot must protect its own existence unless it does not conflict with first or second law. No matter how firmly they will stick to these rules, they will always be confused to see how carelessly and easily we Humans ignore all the laws that we make for ourselves. So in the future only this will be the single distinction to find out the difference between a human intelligence and an artificial intelligence. |
|
Science Quiz
1. Name the winners of this year’s Nobel Prize in Physiology or Medicine. For which discoveries have they been selected for this most prestigious award of the world? 2. US scientists have recently cloned for the first time in the world a wild endangered animal. This is also for the first time that genetic material from a dead animal has been retrieved and brought back to life. Which is this Indian animal? 3. Another application of physics to medical science! A new technique uses the heat generated by alternating current of a suitable frequency to burn tumours of liver cancer. Can you name this technique, which has not yet arrived in India? 4. Which main product is obtained when aluminum-27 is bombarded by an alpha particle? What is the historical importance of this reaction? 5. What is common between podophyllum, aconitum, rheum picorhiza and taxus? 6. Alum is used in dyeing industries for the production of mordants and pigments, in dressing leather, in fireproofing, in waterproof fabrics, as a coagulant for water purification, etc. What is the chemical name of alum which is also used medicinally as a styptic and astringent? 7. Both Celsius and Fahrenheit scales of temperature are based on two fixed points. But another international temperature scale, mostly used for scientific purposes, is based on 20 fixed points. Can you name this scale? 8. Where can you find Pinwheel Galaxy (M 101), Bode’s Galaxy (M 81) and Owl Nebula (M 97)? 9. The porous pot of a Leclanche cell contains a carbon rod surrounded by a mixture of manganese dioxide and carbon powder. What is the function of carbon powder in it? 10. To protect environment from further degradation, a global action plan has been drawn for the 21 century. It includes goals and objectives as well as strategies and actions to be taken to achieve these goals. What is this action plan commonly called?
Answers 1 Swedish Arvid Carlsson, US Paul Greengard and Eric Kandel; for discoveries about how messages are transmitted between nerve cells, called “slow synaptic transmission” 2. Gaur or the Indian Bison 3. Radio Frequency Ablation 4. Radioactive phosphorus; it led to the discovery of artificial radioactivity 5. These are medicinal plants which grow in hills and are endangered 6. Hydrated potassium aluminium sulphate 7. International Practical Temperature Scale 8. In the constellation Ursa Major (Saptrishi) 9. To reduce the internal resistance of the cell 10. Agenda-21.
|
|
New products & discoveries Cradle that can spot the silence THIS is not one of those here-today-gone-tomorrow medical devices. It is a new concept of clinical measurement for assessing hearing and other general functions in a new-born. It comprises low-cost cradle which can be used in any maternity ward. Early diagnosis, before speech and social habits are formed, improves the effectiveness of remedial treatment. Normal new-born babies have a well-defined threshold for motor response to an auditory stimulus. The system detects abnormalities in the pattern of response to sound in the newborn. The baby lies on a sensitive foam mattress and moulded head rest containing transducers for detecting head turning when a sound is made. A band over the abdomen contains a sensor for detecting respiration. Ear probes both carry the stimulus to the child and monitor it with integral microphones. This is a completely self-checking unit and has a built-in “debug” programme to detect electronic and computer faults. This concept in clinical measurement is applicable in screening and research programmes. Screening can alert the child specialist to the presence of other abnormalities such as respiratory problems, neuro-muscular disorders and jaundice.
Plastic as hard and clear as glass A new process to rapidly and cheaply coat plastic sheet panels and foils with a scratch-proof glassy layer to prevent them from frequent scratches has been developed by German scientists. Quartz glass is evaporated and then deposited on the plastic surface in the method developed at Fraunhofer Institute of Electron Beam and Plasma Technology (FEP) in Dresden. Application of intensive quartz glass plasma during evaporation results in coating of extreme hardness and resilience, reports Fraunhofer Gesselschaft Research News. The system can coat foils or sheets with a width of up to 40 centimetres, but in principle coating widths of several metres are quite possible. The coating speed with plasma-activated high-rate electron beam evaporation is around 100 times greater than with other vacuum coating processes — applying a thickness of up to a micrometer per second. Clear and hard glass surfaces of this kind open up new potential applications of plastics — in car windows and headlamps, solar collectors, floor coverings and wall panels. A thin surface coating only six micrometers in depth makes the plasticas wear-resistant an normal glass. The high speed of the process substantially reduced costs — and the greater the volume of plastic coated, the less expensive the job becomes.
Nuclear blast in 3-D COMPUTERS for the first time have simulated the beginning of a hydrogen bomb blast in full-scale 3-D, Associated Press reports quoting Los Alamos National Laboratory in USA. The simulations are a major step toward replacing underground nuclear test blasts. The simulations took 12 days to run using superfast computers at Los Alamos, Lawrence Livermore and Sandia National Laboratories. The simulation was run by a super computer capable of performing 1.6 trillion calculations per second. A Lawrence Livermore simulation showed the detonation of the plutonium spark plug that starts a hydrogen bomb blast. The Los Alamos simulation showed the second step, when a burst of radiation from plutonium ignites the fuel that gives a hydrogen bomb its big blast. Nuclear weapons scientists in the past have devised two-dimensional computer simulations.
Archimedes’ lost words SCIENTISTS at Rochester Institute of Technology (RIT) in USA are restoring a 10th century manuscript the only known copy of the writings of Greek mathematician Archimedes. The text, which was damaged by a monk who erased it 200 years after it was written, was purchased anonymously at a 1998 auction for two million dollars. Using digital cameras and processing techniques as well as ultraviolet and infrared filters, the scientists captured images of the original words and drawings that were washed away and then covered with a new text. “There is always a residual traces of what was there,” said Robert Johnston, RIT professor Emeritus. “It’s amazing what can come out. Soon, nothing will be secret or hidden.” The manuscript is the only copy in the original Greek of Archimedes’ theory of flotation of bodies. The text and diagrams also detail his mathematical treatises and mechanical theorems and contain the roots of modern calculus and gravitational theory. The book disappeared from the Convent of the Holy Sepulchre in constantinople in the 1920s. It resurfaced in the possession of a French family in the 1930s and was sold by the family in 1998.
|
 |
|
