The Tribune, Chandigarh, India

Now computers from bacteria
by Radhakrishna Rao
THE world over, intense research and development efforts are on to overcome the limitations imposed on the current generation computers based on silicon chips. The crunching speed and storing capacity of the conventional electronic computers are already close to the ultimate barrier. As such, the quest to develop superintelligent machines capable of recognising speech and pattern as well as taking decisions has become all the more pronounced.

The benign background noise
by Renuka Rai
IN real life, there is always some noise in the environment. This background noise usually interferes with our capacity to function efficiently. If noise is too much, we even call it pollution. Same happens with the functioning of electronic or electrical devices as well as making sensitive measurements in a scientific experiment. That is why study of noisy systems (those embedded in noisy environments) has received great attention in past years. Stochastic processes are those in which noise and hence randomness play important role. But it comes as a surprise that background noise can be sometimes useful as well. Instead of obscuring some signal, i.e., meaningful message, it can under suitable conditions, enhance the signal.

Science Quiz
by J. P. Garg

New products & discoveries

Response

Now computers from bacteria
by Radhakrishna Rao

THE world over, intense research and development efforts are on to overcome the limitations imposed on the current generation computers based on silicon chips. The crunching speed and storing capacity of the conventional electronic computers are already close to the ultimate barrier. As such, the quest to develop superintelligent machines capable of recognising speech and pattern as well as taking decisions has become all the more pronounced.

Surprisingly, researchers are looking at the protein of unicellular bacteria as well as the human brain and nervous systems of animals like leech and squid to build an ideal biological computer running on biochips forming a part of the electronic circuitry. For such biological computers could perform the tasks beyond the capability of present generation of number crunching machines which at best are robots that perform as per the manipulations of their human masters.

All said and done, there is no unanimity as yet regarding what really constitutes a biological computer. But then, a majority of researchers point out that a computer driven by a chip stuffed with material derived from a living organism could be called a biological computer. But then researchers are not optimistic about realising a biological computers for mass use before the year 2005. In many ways, an ideal biocomputer is expected to resemble a human brain hailed as the “perfect supercomputer engineered by nature.”

Of course, for nearly two decades now Russians, Americans and Japanese have all been active in developing biochip. Of course before the breakup of the Communist empire, the Soviet Union had done pioneering work in developing technology and materials for building biological computers. The Soviet Institute of Biological Physics had developed a memory device from a bacterial protein that is photosensitive.

The most favourite material of researchers working on the biological computer is the protein extracted from the bacteria E.Coli, hailed as the workhorse of the genetic engineering to develop a chip capable of increasing the storing capability of a computer manifold. For hundreds of thousands of years now, this primitive unicellular organism has been in the business of protein synthesis — the basis of life process — much the same way as the modern computer does its job of information processing and data analysis.

In India too, a researcher at the Bangalore based Indian Institute of Science (IISc) has covered much ground in developing a biochip. This biochip being developed by Dr K.P.J. Reddy of the Aerospace Dept is based on bacterial protein working in tandem with laser beams of different colours and varying intensities. As observed by Dr Reddy the biochip being developed by him would help increase the storage capacity of a computer by a substantial extent. He is clear in his vision that more memory space is needed because though the speed of processing has increased manifold over the last one decade, the storing capacity has gone up by just tenfold.

Bacterial protein mixed with a polymer used as a binding agent constitutes the backbone of this biochip. And laser rays help in reading and writing. The storage capacity of this biochip is 300 times more than the “Read Only Memory” used in the conventional computers. It is the unique capability of this bacterial protein which changes its orientation following the use of laser rays that makes it an ideal stuff for use in a biochip. However, Dr Reddy says that much work needs to be done before his dream of building a biochip becomes a reality.

In Japan the thrust of biological computing research has been on developing the so called biological neural networks that simulate nervous system of living organisms. Neural cells possess electrochemical properties that will be useful in building high performance biochips. As such, Japanese biological researchers are keenly analysing the nervous system of leeches, squids and bugs to develop a computing system endowed with a discriminative faculty.

It is felt that a better insight into the physiological and anatomical characterstics of the nervous system of various living species can help researchers devise a computer that mimicks human brain.

On another front, spectacular advances in genetic engineering and biotechnology have been nudging a number of researchers to make use of DNA (Deoxyribose Nuelie Acid) as a biocomputing material par excellence. Today there is a global quest to turn DNA into a biologicial computing system. For instance, in 1994 Leonard Alderman, a computer scientist at the University of Southern California, Los Angeles, showed that a large number of DNA molecules could help solve a range of complex problems. The thrust of Alderman’s research is directed towards preparing many sequences of DNA and use them to solve a particular problem. In this way, he could zero in on the most optimal airline flight path between several cities in a map so that each city is visited only once.

The benign background noise
by Renuka Rai

IN real life, there is always some noise in the environment. This background noise usually interferes with our capacity to function efficiently. If noise is too much, we even call it pollution. Same happens with the functioning of electronic or electrical devices as well as making sensitive measurements in a scientific experiment. That is why study of noisy systems (those embedded in noisy environments) has received great attention in past years. Stochastic processes are those in which noise and hence randomness play important role. But it comes as a surprise that background noise can be sometimes useful as well. Instead of obscuring some signal, i.e., meaningful message, it can under suitable conditions, enhance the signal.

In recent years, such a phenomenon has been discovered and it goes by the name of Stochastic Resonance (SR). It was proposed in 1981 as a possible mechanism for explaining the long standing riddle in climatology. The riddle is this: Earth has been regularly experiencing ice age every 100,000 years. But it seems to be governed by random events. Geologists know only one thing which has periodicity comparable to this, the wobble in the earth’s orbit also occurs after every 100,000 years. But this in itself is not capable to cause a major freeze. There are other large scale fluctuations (noise) in the atmosphere. But noise alone cannot cause periodicity. So it was proposed that strong noise, somehow, acts together with a weak periodic signal (wobble) and that accounts for the occurrence and regularity of ice ages.

Although, for the ice age phenomenon, SR remains more of a conjecture, but it caught imagination of many scientists who applied it for many different systems in physics, and biology.

To appreciate the phenomenon of SR better, consider a bistable potential as shown in the figure. The particle can be in either of the potential wells. The switching to the other well requires a definite energy, which is called the barrier energy. When we apply a weak periodic signal, the energies of the two wells start changing in time (they swing back forth around the zero signal value and alternatively one well becomes more stable than the other). As a consequence, barrier energy also shows periodic changes. If the applied signal is strong enough that it overshoots the particle beyond the barrier energy, switching to the other well occurs. This switching is a to and fro phenomenon between the wells and it happens at the frequency of the applied signal.

However, if the applied signal is weak, the barrier energy is not surpassed and the particle stays in a particular well. Here, the constructive role of noise comes in. A small amount of noise given to the system induces switching. Surprisingly enough, the frequency of the signal remains same as of the applied signal.

The extent up to which the applied signal benefits from the random noise, depends on the intensity of noise, and their relation is nonlinear. The quantitative measure for this is the signal to noise ratio. (SNR).If the noise is too little, the output signal (switching) is not enhanced significantly. Similarly, high quantities of noise also mask its constructive role. But in between there is an optimum value of noise at which SNR is maximum.

The counter-intuitive thing in this phenomenon, if any, is that (within a certain range) adding more random noise actually results in more regular switching between the two wells, and not less. Over the years SR has been demonstrated in a wide variety of physical systems, including electrical switches, lasers and superconducting quantum interference devices. The important of all systems showing SR, is the presence of a threshold (of energy). The response of the system is not evident or significant if the input signal is below threshold. But in the presence of little noise, the output signal is boosted.

An interesting example from biology will help to clarify this point. The ordinary crayfish possesses mechanoreceptor cells on its tail fan. These cells end in fine hair between 25 and 100 microns (millionth of a metre long and they are specialised to detect weak water motions, which may be the periodic signals generated by the waving tail of some predator in water closeby. These hair when stimulated cause a nerve impulse to be generated in the sensory neuron attached to it. However, these neurons act as threshold detectors. If the intensity of simulation to hair is quite weak, no nerve impulse is generated. Now, some kind of noise is always present in the real environment. So this poses an interesting possibility to explore any noise-boosted phenomenon. SR was in fact observed in the crayfish’s sense organs. Thus the sensitivity of its hair is enhanced in the presence of noise. Of course, here also an optimum level of noise is important.

It is suspected that SR or some related phenomenon might be functional in the activity to brain. SR is being studied in simple models of neurons. SR holds promise for medical science also where some disorders are related to the increased sensory threshold (reduced sensitivity). Addition of noise may be able to improve the firing rates of affected neurons.

Science Quiz
by J. P. Garg

1. German physician Christian Freidrich Samuel Hahnemann founded a system of medical treatment known as Homoeopathy, based on a new idea. Can you state this idea in three words? Name also the book in which he stated his ideas.

2. British scientists have recently discovered a new dangerous “greenhouse gas”, one molecule of which can trap 28,000 times more heat than that trapped by a molecule of carbon dioxide, the most effective greenhouse gas known till now. Can you name this new man-made gas the source of which is a mystery yet?

3. “Black box” is a flight recording device uses in aeroplanes. One type of this device is called data recorder. What is the other type called?

4. High or low blood pressure is a common ailment which can cause depression, hypertension, paralysis, heart stroke, etc. Which hormone in our body controls blood pressure?

5. Most plants grow by seed germination. But in seeds there is a specific part from which the first shoot emerges. What is this part of the seed called?

6. Benzene is obtained when sodium salt of benzoic acid is heated with a substance X or when phenol is heated with a substance Y. Identify the substances X and Y.

7. Atomic clocks are most accurate clocks which remain unaffected by factors such as atmospheric pressure, temperature and movement of the earth. Which natural periodic phenomenon is involved in the working of these clocks?

8. A quantum of light vibrations is called a photon. What is a quantum of lattice vibrations in a crystal latic called?

9. These animals are toothless, have long, narrow snouts, long tails and overlapping thorny scales. They have sticky ropelike tongues that they stretch out to catch the ants on which they feed. To protect themselves from their enemies, they can rool themselves into hard, tight balls. Which animal are we talking about?

10. Shanti Swarup Bhatnagar Awards are presented every year to Indian scientists. Which organisation gives away these awards of which Bhatnagar was the first director?

Answers

1. “Like cures like”; “Materia Medica” 2. Trifluoromethyl sulphur pentafluoride, also named SAF-5 CAF-3 3. Cockpit voice recorder 4. Vasopressin 5. Radicle 6. Soda lime and zinc dust respectively 7. Radioactive transitions of the element caesium 8. Phonon 9. Pangolin 10. Council of Scientific and Industrial Research.

New products & discoveries

Instant energy in a bottle
The 0.5 litre rechargeable high pressure gas bottle attached here to a thermal imaging camera supplies the vital pure air for the equipment’s efficient operation.

This bottle is one example of a technique for providing novel form of energy for aerospace, defence and industrial uses.

Called pneumatic energy stores, the bottles can be tailor-made in a variety of shapes and sizes to fill whatever space remains on a designer’s drawing after the parts they will be energising of driving have been packed in.

The company has developed special techniques for storage of gases at very high pressure up to 1150 bar (17,000 psi). These techniques provide a “single shot” or rechargeable power source of high energy density available for instant use at any time over a period of more than 10 years.

The bottles are machined from high grade stainless steel to ensure strength and freedom from impurities and are then electron beam welded to make them leak-tight, and inspected to ensure their safety.

In addition to manufacturing the bottle, the company has also developed light-weight air compressors for recharging them. It has also developed a range of rapid inflation systems for airborne, surface and underwater use.

Colour changing spoon
A reusable plastic spoon which can change colour when food is too hot to feed a baby has been developed by a London-based company.

The baby safety feeding spoon, developed by B&H Liquid Crystal Devices, is part of a range of colour-changing safety products designed to reduce accidents involving children.

The spoon’s colour-changing feature ensures that danger is highlighted instantly and reveals - by yet another colour change - when the temperature is correct.

Colour-changing resins constitute a breakthrough in the field of temperature safety, not only for babies but also for parents who could burn their own mouths when testing the temperature of the food before giving it to a baby. Because an adult’s mouth is less sensitive than an infant’s, testing the food first is no guarantee of assessing the correct temperature.

The unique feeding spoon is moulded from polypropylene, a non-toxic, unbreakable plastic and can be sterilised. It is coated with heat-sensitive material similar to that used for medical thermometers.

The colour-change occurs at a pre-set temperature, above which scalding is likely to occur. The coating is normally blue but other colours are available, reports British Commercial News.

If the food is too hot for the baby, the coating will turn pink. Only when the food on the spoon or in the dish is of a safe temperature, the spoon’s colour returns to its original hue.

New colour video displays
Colour displays that can be made using a simple “printing” process will provide ultra-cheap video screens for the next generation of cellphones and palmtops, says British researchers.

In London, a team from Cambridge Display Technology (CDT) and Seiko Epson of Nagano in Japan demonstrated the world’s first full-colour video screen to use arrays of red, green and blue light-emitting polymers (LEPs).

Unlike complex liquid crystal displays, LEPs have a wide viewing angle. And because they need no backlights, colour filters or polarisers, they are far simpler to make, says CDT’s technical director Jeremy Brroughes, a member of the team that developed LEPs at the University of Cambridge in 1989.

The team found that a polymer called PPV will emit light when a voltage is applied to them. Because PPV molecules contain benzene rings, which allow electrons to move through the molecule, the polymer can act as a semiconductor and form the basis of a light-emitting diode, reports New Scientist.