Chandra X-ray observatory
by D.P. Singh
THE most powerful space-borne observatory to study X-rays from the stars has been recently launched by NASA. It is named Chandra X-ray Observatory after the Indian-born Nobel laureate S. Chandrasekhar, who is known for his pioneering work on the evolution of stars. The observatory is expected to bring about a revolution in X-ray astronomy.

Science Quiz
by J. P. Garg

Manipulating intelligence gene
by Kalpish Ratna

ARE you man or mouse? A question that must give pause if it relates to intelligence. A new piece of research is all out to prove that 98 per cent of the time, man and mouse are practically indistinguishable. Learning and memory, the twin blessings that compact for intelligence are coded by a gene that’s almost similar in mouse and man. And this very gene that codes for intelligence now has been upgraded.

Recently scientists reported in Nature that the learning gene in mice has been engineered to make a better class of rodent, one that’s smarter, more savvy to danger, with a heart for adventure and a head for past mistakes. The new mouse on the block is the brainchild of Joe Z. Tsien, a neurobiologist at Princeton, who is quite happy to state that since the DNA sequence of the mouse gene is so similar to that of human beings, his super rats definitely presage superbrats.

Tsien’s discovery that the learning gene can be manipulated will mean hope for millions of victims of illnesses that cause forgetfulness and loss of learning skills — Alzheimer’s is only one of them. It has been welcomed by neuroscientists the world over. Less enthusiastic is the response to Tsien’s suggestion that normal intelligence can be manipulated. A flurry of scientific alarm has been set off by the very idea that manipulating the learning gene may produce superbrats who learn faster, remember more and dare more than their parents ever did. But stop right there — don’t our kids, already?

Tsien’s Super mouse came through with flying colours in six different tests. It picked its way carefully past a submerged platform in its water tank without bumping its head, a laboratory standard of rodent poise

More, it displayed an eager curiosity in exploring objects it had never seen before. House-holders may consider it naive to award points for this one. Domestic mice will explore just about anything, but apparently laboratory mice are a more exclusive set.

Tsien has named his super mouse Doogie after the insufferable Doogie Howser MD, the TV prodigy.

What is this learning gene all about? It codes for a protein called the NDMA receptor on the membrane of nerve cells in certain parts of the brain, mainly the hippocampus.

The NDMA receptor has long interested neurobiologists. It could play an important role in memory. This receptor needs two separate stimuli before it shrills its signal through the cell. More interesting is the finding that the NDMA receptor has two components. The first, the NR2B subunit is common in very young mice. The other, the NR2B subunit is more frequent in ageing mice. It’s the NR2B unit that jolts the nerve cells into prolonged activity. Researchers think therein lies the secret of what our ancestors knew so well: teach them young. Young animals learn better simply because the NR2B receptor in their brains jogs the memory faster. As we age, man, mouse and monkey, alike, our NR2B receptors begin to fade away.

The Princeton neurobiologists gave Doogie extra copies of the gene that codes for the NR2B subunit. This means that Doogie has an enhanced youthful potential for memory. Cells harvested from the hippocampus showed increased electrical activity.

This puts memory and learning in a new perspective. It suggests that childhood may become an intensive camp for more complex and analytical forms of learning, if the learning gene can be manipulated.

Scenarios may vary from just getting a dull child to improve his performance in school to cultivating talent to the heights of genius. And how is all this to be accomplished? By gene therapy or by finding drugs that will enhance NDMA receptor activity, says Tsien confidently. And now we have Doogie to show us how.

This does not necessarily mean that plugging a new drug into this site will make a whiz kid out of a dunce. Learning may have more to it than a single gene. Memory may be more complex than the switching on or off a receptor site, and the brain may not really have an endless capacity to store useless information. Perhaps growth is learning to forget.

And what of memory’s minefield? Imagine being condemned to remember the dropped brick, the botched plan, the dashed hope! That way madness lies. Perhaps the occasional bump from a sunken bar is just what Doogie needs to thrive.

— ANF

Chandra X-ray observatory
by D.P. Singh

THE most powerful space-borne observatory to study X-rays from the stars has been recently launched by NASA. It is named Chandra X-ray Observatory after the Indian-born Nobel laureate S. Chandrasekhar, who is known for his pioneering work on the evolution of stars. The observatory is expected to bring about a revolution in X-ray astronomy.

In the field of X-ray astronomy Chandra represents a new beginning. Its improved sensitivity is expected to make possible detailed studies of supernovas, quasars, black holes and dark matter present in our universe. Thus Chandra will turn a new leaf in our understanding of the origin, evolution and destiny of the universe.

The observatory has been built at a cost of $ 1.5 billion. Its length is 13.8 metres. It has four sets of concentric barrel-shaped mirrors, which can bring X-rays from distant sources to a much sharper focus than ever possible. Chandra’s highly polished mirror surfaces have been given coatings of high-density iridium to greatly increase their collecting efficiency.

The observatory is also equipped with specially designed diffraction gratings enabling it to distinguish between X-rays of different wavelengths better. After launch from space shuttle Columbia on July 23, 1999 Chandra has been placed in a highly elongated orbit, which enables it to spend nearly 80 per cent of its time collecting scientific data.

It orbits the Earth every 64.2 hours. It comes within 10,000 km of the Earth at its nearest approach and is as far away as 140,000 km at its farthest point. At its farthest point Chandra is at a distance equal to the one-thirds of the distance to the Moon.

Chandra is world’s most powerful X-ray telescope. It has eight-time greater resolution and will be able to detect sources more than 20-times fainter detected by any previous X-ray telescope. Its resolving power is equivalent to the ability to read a stop sign at a distance of 20 km. Chandra can observe X-ray from particles up to the last second before they fall into a black hole.

The electrical power required to operate the observatory and its instruments is only 2 kilowatts. The amount of electrical power is less than the power needed to run a room airconditioner. Chandra is the largest satellite every launched from a space shuttle.

The star-filled night sky appears serene and calm. But the universe is much more exciting and explosive. There are many violent processes that go on inside stars and galaxies. These processes give rise to penetrating radiation like X-rays and gamma rays. The study of these rays, especially X-rays, can throw new light on the nature of exotic objects like supernova remnants, quasars and black holes.

X-ray astronomy is only about five decades old. The first X-ray pictures of the sky were taken in 1947. These pictures showed that the Sun does emit X-rays. Later observations showed that the high activity areas on the Sun such as sunspots, corona and solar flares were the sources of these X-rays.

Apart from the Sun, there are many other sources of X-rays in space. These sources include remnants of supernova explosions, binary star systems (having one of the components as a white dwarf, a neutron star or a black hole), extremely hot gases in galaxies and star clusters. All these sources emit X-rays by extreme acceleration of electrons in a strong magnetic field.

The discovery of an X-ray source outside the solar system was made in 1962. It was discovered in the direction of the constellation Scorpios. The source came to be known as Scorpios X-1. Later on several more celestial X-ray sources were discovered. Prominent among these are the Crab Nebula and Cygnus X-1.

In the whole sky about 60,000 X-ray emitters have been discovered till date. Chandra is expected to raise this number several-fold. It is expected that Chandra will unearth about 1000 new X-ray sources in every patch of the sky, the size of the full Moon.

Programmers at the Chandra Centre (USA) have developed special software to analyse data that has started raining down from the orbiting observatory. In the field of high-energy astronomy, Chandra has ushered in an era of routine high resolution X-ray imaging and X-ray astrophysics.

Science Quiz
by J. P. Garg

1. Daughter of a famous English poet, she became the first computer theorist at the age of 19 when she drafted the basic rules of computer programming. The most commonly used programming language for artificial intelligence has been named in her honour. Can you name this self-taught system analyst?

2. Japan recently experienced its worst-ever and the world’s third - worst nuclear accident when radioactive radiation leaked from a uranium processing plant which exposed more than 50 persons and kept more than 3.2 lakh people confined to their homes. Where did the earlier two nuclear accidents worse than this one take place and when?

3. Name the chemical that is used as ‘fixer’ in photography.

4. RBCC is a hybrid rocket-jet engine that can propel an aircraft from take - off to supersonic speeds (speeds more than that of sound) by using a combination of air breathing and rocket propulsion techniques. What is full form of RBCC?

5. The point nearest to the earth in the orbit of the moon or of an artificial satellite is called perigee. What is the point nearest to the sun in the orbit of a planet or a comet called?

6. This dinosaur was characterised by the presence of two rows of bony plates on its back, which were used by the dinosaur not only for defence but also for controlling body temperature (thus these plates acted as a natural thermostat). Which dinosaur are we talking about?

7. The projector in a cinema normally projects 24 pictures per second on the screen but we see the picture continuously. What is the principle called that explains this phenomenon?

8. Over a long period of time, water resources like rivers and lakes get enriched with nutrients like nitrates and phosphates due to the heavy use of nitrogen fertilisers and increased discharge from sewage works. What is this process called, which can create serious economic and ecological problems?

9. Name the instrument generally used to measure the radius of curvature of a spherical surface like that of a lens or a mirror.

10. What is the science of study of possible existence of life beyond earth and its atmosphere called?

Answers
1. Lady Ada Byron King 2. Three Mile Island in the USA in 1979 and Chernoby1 in erstwhile USSR in 1986 3. Sodium thiosulphate also called ‘hypo’ 4. Rocket - based Combined Cycle 5. Perihelion 6. Stegosaurus or “roof lizard” 7. Persistence of vision 8. Eutrophication 9. Spherometer 10. Exobiology.

Latest version of bullet train
The latest version of Japan's famed bullet train lacks the nose that gave it its name. Advances in aerodynamic theory, extensive computer modelling and wind-tunnel testing with prototypes have yielded trains with noses shaped like the duck's bill. The train runs between Tokyo and Fakuoka at the western edge of the Japan. They now have a top speed of 177 mph, versus the 137 mph of older bullet trains.

Microscopic devices for transplants
A US researcher has developed a method for implanting tiny silicon capsules carrying health transplant cells beneath a patient’s skin, which take the place of malfunctioning cells by producing chemicals needed for the body.

The new method, developed by Mauro Ferrari, a biochemical engineer at Ohio State University, eliminates the need for immunosupression, and for transplanting an entire organ when a few grams of healthy cells will do.

Today, doctors suppress patients’ immune systems with drugs to keep antibodies from destroying transplanted tissue, leaving patients open to infections.

Ferrari and his colleagues were able to create 2-millimetre capsules, each containing millions of channels only 18 nanometres long, approximately 50 atoms across, according to a report in the journal Membrane Science.

Other researchers have tried to construct similar capsules from plastics, but the materials were incompatible with the body, and could not provide immunoisolation for a sufficiently long period of time, Ferrari explains.

He and his colleagues chose silicon because it would not react with the body, and because the computer industry had already developed methods for creating precise surface features with the material.

The patented method employs photolithography, a technique in which microchip manufacturers take a smooth layer of silicon atoms and eat away portions of the surface with chemicals. The holes that result are all the same size, down to an atom.

Insulin-dependent diabetes develops when the body fails to recognise cells in the pancreas that respond to glucose and produce insulin.

One possible therapy is to transplant even just a few grams of healthy pancreatic cells.

A capsule containing the cells could be inserted under the skin anywhere in the body. Molecules of glucose would enter the capsule, and the transplanted cells would release insulin, which would flow back out.

Determining the right hole diameter was difficult, according to Ferrari, because the size of these molecules is not precisely known. Initial tests revealed that both insulin and glucose could pass, though with difficulty, through 18-nanometre holes.

The researchers then inserted a silicon membrane containing 18-nanometre holes between two chambers of liquid, one containing IgG. Over the next four days, they measured the amount of IgG that penetrated the membrane.

After a day, the concentration of IgG in the second chamber was less than 0.4 per cent. After four days, the concentration had grown to just over one per cent.

Ferrari characterises this rate as several times slower than capsules made of plastic. He cites a similar study in which a perforated plastic membrane allowed an IgG concentration of one per cent to accumulate in the second chamber after only 24 hours.

Keeping out 100 per cent of all IgG may be impossible. Researchers think the molecule is not spherical, and if it enters an opening with its narrow end, it can squeeze through.

These molecules twist and turn and find their way into small passageways — that’s what makes them good antibodies, Ferrari says.

A capsule could produce all the insulin a patient needs for a year for about $ 20. Clinical trials would be done within three years, Ferrari hopes.

New methane source
RESEARCHERS in the USA have come up with a new process to produce methane from a naturally-accruing iron-nickel alloy using pressure and heat.

The process, if it occurs in the earth’s crust, could imply a source of methane other than digestion or decomposition of dead organic matter, the scientists say.

The researchers call their process abiogenic—i.e., not connected with biological processes — methane formation, according to a report in Science.

Most methane is thought to be produced when dead organic matter decays through the action of microbes or by heat-induced decomposition.

Other means to produce methane in the laboratory exist, but Michael Berndt, a senior research associate in geology and geophysics at the University of Minnesota, says the new process could be an important means of generating methane in nature — specifically, under conditions of heat and pressure found deep in the earth’s oceanic crust.

Developed by Berndt and Juske Horita of Oak Ridge National Laboratory, the new process produces methane from bicarbonate ions and hydrogen at temperature up to 400 degrees C. The catalyst for the conversion is an iron-nickel alloy found in certain parts of the oceanic crust.

Although the researchers are not sure of the percentage of methane that may be generated through the process, they believe some methane thought to have been produced by bacteria may actually have been produced abiogenically.

Berndt says the methane produced was chemically difficult to distinguish form organically produced methane.

Gene mutation detection method developed
A SIMPLE way of detecting tiny genetic mutations responsible for medical conditions, including cystic fibrosis and cancer, has been developed by US researchers.

Those alterations, called single nucleotide polymorphisms, occur when one chemical component of the genetic code is changed in some way by additions, deletions or relocations of genetic material, the scientists say. Knowing what and where those changes are is critical to finding and designing drugs that can act on them specifically without interfering with the activity of healthy genes.

The new method developed by chemists at the University of North Carolina at Chapel Hill could allow scientists to screen minute changes in the genetic make-up of humans, animals, plants or viruses, according to a report in the journal Chemistry and Biology.

Comparable techniques already available for screening genes are confined to research laboratories, are labour intensive and are, therefore slow and expensive, the researchers say.

The method uses inexpensive electronic equipment without cumbersome procedures and is based on the measurement of different but very small electrical currents generated when guanine (a fundamental component of nucleic acids in DNA) is paired with its correct DNA chemical partner versus an incorrect chemical partner.

The incorrect chemical is single nucleotide polymorphism mutation or SNP. With the new technique, specific mutations associated with specific diseases can be detected, the researchers say.