Genetic effects of radiation
K.S. Parthasarathy
MANY scientists, physicians, journalists and members of the public believe in the myth that birth defects are more common among the children of the survivors of the atomic bombings at Hiroshima and Nagasaki. In 1945, when the bombs were dropped, these cities had an estimated population of 310,000 and 250,000. About 90,000 - 140,000 in Hiroshima and 60,000 - 80,000 people in Nagasaki died immediately or within two to four months after bombing, resulting from collapse of houses caused by the blast and from heat rays and fires and radiation exposure. In the 1950 Japanese national census nearly 280,000 persons stated that they “had been exposed “ in the two cities.

Preventing leakage in buildings
Raj Kumar Aggarwal
WITH the onset of monsoons/rainy season, most of the house owners feel worried about leakage. The coming out of water from roofs, walls and toilet floor of a building is called leakage. Being common in buildings, leakage causes efflorescence, damage to wall finishes like distempering and painting. It also damages household articles, short-circuiting of electric wiring and crumbling of cement plaster from walls. Sometimes the main reason of major cracks in walls of a building is leakage from water supply lines.

A satellite devoted to science
INDIAN astronomers and space scientists are poised to join a select class of space observers once their newly proposed national “multiwavelength astronomy” mission “astrosat” gets under way. Astrosat will be the first Indian satellite completely devoted to science, according to the Chairman, Indian Space Research Organisation (ISRO), Dr K. Kasturirangan.

NEW PRODUCTS & DISCOVERIES
Diesel substitute found
Rural Indians have a potential substitute for diesel right in their backyards, claim the scientists at the Bangalore-based Indian Institute of Science (IISc). They have shown that oil extracted from seeds of “Honge tree” (Pongamia pinnata, Karanj tree in Hindi) found all over the country can power existing diesel engines without causing pollution.

• Mosquito hunt in forests
• Water plant as per its needs
• BP reading on your wrist
• Micromirrors to measure objects
• Cheaper, lighter elegant structures

SCIENCE QUIZ
J. P.  Garg tests your IQ

Genetic effects of radiation
K.S. Parthasarathy

MANY scientists, physicians, journalists and members of the public believe in the myth that birth defects are more common among the children of the survivors of the atomic bombings at Hiroshima and Nagasaki. In 1945, when the bombs were dropped, these cities had an estimated population of 310,000 and 250,000. About 90,000 - 140,000 in Hiroshima and 60,000 - 80,000 people in Nagasaki died immediately or within two to four months after bombing, resulting from collapse of houses caused by the blast and from heat rays and fires and radiation exposure. In the 1950 Japanese national census nearly 280,000 persons stated that they “had been exposed “ in the two cities.

Radiation can cause mutations in genes. This has been clearly demonstrated in mouse and in fruit flies. The classical experiments of Mueller, the German scientist, are well known. The changes may show up in the offspring as colour of the coat, shape of the wings, etc. But such markers are not available in humans. We require very sophisticated laboratory methods to demonstrate subtle changes in exposed individuals.

Physicians appointed by the Atomic Bomb Casualty Commission, the predecessor of Radiation Effects Research Foundations (RERF) examined 76,626 infants conceived and born in Hiroshima and Nagasaki over a period of six years starting from the late spring of 1948. The researchers did not see statistically demonstrable increase in major birth defects in these infants. While the survey started, certain dietary staples were rationed in Japan. Pregnant women had special provision. Because of this, the surveyors of new-borns could identify 90% of the pregnancies that persisted for at least 20 weeks of gestation.

Physical examination of the new born and autopsies on as many stillborn infants revealed that neither the frequency of major birth defects nor the frequency of the most common birth defects differ significantly with radiation exposure of parents. The researchers examined some 21,788 infants shortly after birth and re-examined them eight to 10 months later. The study covered 65,431 registered pregnancy terminations and appropriate control populations.

In a brief review the Radiation Effects Research Foundation (RERF) cautioned: “The absence of a statistically significant effect of ionising radiation on the frequency of major birth defects should not be construed as evidence that mutations were not induced by parental exposure to atomic radiation”.

Under suitable experimental conditions, the researchers saw mutations in every animal and plant species studied. It may not be appropriate to presume that human genes are not mutable when exposed to ionising radiation. The magnitude of a difference between two or more groups that can be detected statistically depends upon the number of observations made and on the “natural” frequency of the event under scrutiny as well as the difference between the groups resulting from exposure.

The RERF study had the statistical power to detect a doubling of the rate of major congenital malformations, if such defects had occurred. In 1991, Mr Karan Thapar interviewed me on his “Eyewitness” video magazine programme. In the ensuing controversy, I stated that no genetic effects were found among the thousands of children born to the survivors of Hiroshima and Nagasaki. He unhesitatingly contested my statement as “inexplicable”. “Where did Dr. Parthasarathy form the impression that no genetic effects were found among the thousands of children of Hiroshima and Nagasaki”? ……. “The opposite is not just a fact, it is the truth”, he asserted.

I was not surprised. While responding to an opinion survey, over 80 per cent of the participants from reputed academic and research institutions in India stated that genetic effects is the major effect seen in the children of the survivors of atomic bombings.

Nearly 30 per cent of the scientists attending a specialist meeting at the International Centre for Theoretical Physics at Trieste, Italy believed in the myth that double headed monsters were born to the survivors of atom bombings. Where do we go from here?

In my interactions with various professional groups, “genetic effects of radiation” is a topic which elicits maximum questions. Irrefutable evidence on the harmful effects, if any, due to low levels of radiation exposure is unlikely to emerge in the near future. Evidently, it is prudent to reduce all radiation exposures to as low a value as is reasonably achievable.

Dr. K. S. Parthasarathy is Secretary, Atomic Energy Regulatory Board

Preventing leakage in buildings
Raj Kumar Aggarwal

WITH the onset of monsoons/rainy season, most of the house owners feel worried about leakage. The coming out of water from roofs, walls and toilet floor of a building is called leakage. Being common in buildings, leakage causes efflorescence, damage to wall finishes like distempering and painting. It also damages household articles, short-circuiting of electric wiring and crumbling of cement plaster from walls. Sometimes the main reason of major cracks in walls of a building is leakage from water supply lines.

It is important to prevent leakage in the building to provide healthy and clean environment for its occupants. The main causes of leakage are defective construction and poor maintenance. It is estimated that 80% of the leakage take place from roofs/terraces and toilets.

Stagnation of rainwater on roofs due to inadequate slope to the terraces and blockage of down pipes to carry rain water with articles like leaves, papers, plastic bags and building rubbish causes leakage during rains. Regular inspection and opening of clogged pipes with the help of an iron rod can stop the leakage completely. It is more important to provide minimum one 4” dia down pipe for every 400-500 square feet roof area. Moreover the roof surface should be provided with (1 in 60) (preferably 1 in 40) slope to carry rain water efficiently without giving any time to penetrate it into roof. Tile terracing on roofs, if laid with cement mortar mixed with 2% soap solution (prepared by mixing ordinary soap @ 2% by weight of water) provides excellent water proofing property and proves much more effective in checking leakage.

Due to breakage/failure of floating ball valves (provided in all the water storage tanks to disconnect the supply when tank is filled upto the specified level automatically), the water start flowing through overflow pipe and accumulates on roofs also causes leakage. It can be checked by providing sufficient length of overflow pipe up to the nearest down water pipe so that overflow water can be drained off without damaging the roofs.

Leakage of water from fan hooks is a common problem due to less cover of cement concrete on fan hooks during construction. By providing extra layer of cement concrete of (1:1½:3) mix at such specific points (fan hook boxes) leakage can be checked. Provision of 0.10 mm thick polythene sheet between the layers of earth on roofs can further save the roofs from leakage in the areas having constant heavy rains.

Seepage of water through external walls (especially from brick face walls) during rains can be avoided by providing deep cement pointing or cement plaster with water proof compound on external sides of the buildings. In case of severe damage due to constant heavy rains stone cladding on external walls will give good results. Repair and filling of all joints and cracks after removal of weed growth, if any, on the roofs is very important to stop leakage.

Leakage in toilets occurs when good quality and ISI mark pipes, bends and traps are not used and pipes are not jointed properly. To avoid any leakage after the construction, all sanitary pipes, and fittings should be tested for water-tightness either by water test or smoke test before laying the floors. Plumber should be directed to perform such tests in all circumstances. Leakage can also be controlled up to some extent if the floor of the toilet is laid in one panel, without any dividing strips. The joints in tiles of bathrooms are filled with white cement. These joints get loose after continuous use and require periodical maintenance and refilling with white cement to stop leakage. Rusting/erosion of GI pipes due to overthreading during the jointing also causes leakage. All such joints should be covered with some putty of good quality.

There is leakage from water storage tank especially from joints like inlet, outlet, overflow pipe and from wall and slab joints. By constructing walls of water tanks with RCC of (1:1½:3) mix with waterproof compound instead of bricks leakage can be checked. However by applying “Bondest” putty (available in the market) around all such joints and on cracks leakage can be controlled completely.

Leakage not only causes damages to the buildings, it is major sources of colossal wastage of precious treated/filtered water. It has been estimated that due to dripping from one tap 100-150 litres of water is wasted per day. The water taps, valves, washers and cocks are subjected to constant wear and tear due to continuous flow of water under pressure. These require regular maintenance by a skilled trained plumber. Non repairing attitude of building owners proves damaging to the safety of the building and increases its maintenance cost many a fold. It is, therefore, advisable to pay special attention to leak-proofing and to utilise good quality and ISI mark pipes and other fittings during construction of the buildings.

A satellite devoted to science

INDIAN astronomers and space scientists are poised to join a select class of space observers once their newly proposed national “multiwavelength astronomy” mission “astrosat” gets under way.

Astrosat will be the first Indian satellite completely devoted to science, according to the Chairman, Indian Space Research Organisation (ISRO), Dr K. Kasturirangan.

Considered to be one of the major steps taken by ISRO for inter-institutional collaboration, Astrosat could see the involvement of an international partner for a major component of the payload — the ultraviolet imaging telescope, he said here recently.

In 1996, ISRO had asked the Indian astronomers from different research institutions to come out with a proposal for a multiwavelength astronomy.

Tentatively called astrosat, the proposal has been already submitted to ISRO by a team headed by Dr P.C. Agrawal, Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, in April this year.

According to Dr Agrawal, ISRO had only approved the development of “prototype” instruments which should be made available to ISRO by the middle or end of next year. ISRO would in turn review its spaceworthiness and other scientific specifications.

“Only then astrosat becomes a reality,” he said. The proposal entailed an exclusive payload for studying a wide range of wavelength of cosmic energies emitted from various celestial bodies with special reference to ultraviolet bands.

This could be one of its kind as the already existing US, European and Japanese satellites did not have the facility to study the planetary and interplanetary positions in such a wide range of wavelengths, he said.

The newly proposed satellite would have a unique feature of covering a wide energy range of 0.3 KeV to 80 KeV and studying simultaneously the X-ray sources in the optical and ultraviolet bands and to study UV emissions from a variety of cosmic sources thus adding new information to understanding the science of astronomy, he said.

The total weight of the payload is expected to be around 782 kg, Dr Aggrawal said. PTI

NEW PRODUCTS & DISCOVERIES
Diesel substitute found

Honge oil works out to be 25 per cent cheaper than diesel since the seed cake, after extracting oil, can be sold as fertiliser, Shrinivasa and his team reported in Current Science. PTI

Mosquito hunt in forests

Using satellite data and ground information, scientists at the Malaria Research Centre (MRC) in New Delhi have pinpointed the habitats of a deadly species of malarial mosquito in the forests of northeast India and some districts in western India.

The forest species, Anopheles dirus, is “one of the most prevalent and efficient vector of malaria in entire southeast Asia,” according to Aruna Srivastava and her colleagues at MRC who have reported their findings in the journal Current Science.

“Because the species breeds in deep inaccessible forests, their presence cannot be detected by manual survey,” Sirvastava says. Therefore, she and her colleagues used the remotely sensed satellite data and Geographic Information System (GIM) to map the areas where the species is likely to be found on the basis of environmental parameters conductive for their breeding and survival.

Being a forest species, the most influencing environmental parameters for the species existence happens to be forest-cover, rainfall, temperature and altitude, she said. Hence for mapping of GIS distribution of this species, these four ecological variables, which can be sensed by the satellites, were considered. PTI

Water plant as per its needs

Researchers in Israel have developed an irrigation sensor which measures plants’ need for water and adjusts water supply according, thus leading to water saving.

The sensor, developed by Yehoshua Sharon and Ben-ami Bravdo at the Hebrew University of Jerusalem’s faculty of Agriculture, increases the yield of crops and dramatically reduces water usage by up to 60 per cent for some crops.

At the heart of the system is an electronic sensor that clips onto a plant leaf and measures its thickness to an accuracy of one micrometer.

“A leaf’s thickness is dependent on the amount of water in a plant,” says Sharon. “A healthy leaf is 60 per cent water.” A thin leaf is a sure sign that the plant is suffering stress because it is thirsty, and stress is bad for yields, a report in New Scientist said.

The sensor consists of two plates, one fixed and the other spring-loaded, which together grip the leaf. The moving plate is connected to the small potentiometer that regulates the voltage in an electrical circuit.

As the leaf’s thickness changes, the plate moves, causing a change in the voltage. This signal is fed to a processor that adjusts the plant’s water the plant’s water supply. PTI

BP reading on your wrist

Boss Causing your blood pressure to rise? With this wrist monitor, the smallest you can buy, you’ll know exactly when to schedule your next yoga class.

More than 50 million Americans suffer from hypertension, and many manage their disease with bulky home blood-pressure monitors. This sleek device also stores readings to track progress. Price $ 119. www.omronhealthcare.com Popular Science

Micromirrors to measure objects

Scientists have developed an inexpensive optical measuring device that measures the height and location of even the smallest of objects.

Uptil now three-dimensional imaging of a living cell was achieved with a sophisticated optical device and the data was acquired using a confocal microscope, whose closely focused beams scanned the cell point for point and layer for layer.

A rotating disc containing tiny holes allowed light to pass onto the section of the object being scanned, while blocking out the light both ahead of and behind it — thus allowing the microscope to scan only one surface at a time.

Researchers at the Fraunhofer Institute for Production Technology IPT have now developed a prototype of an optical measuring device that operates similarly, but without perforated disks. PTI

Cheaper, lighter elegant structures

Scientists have come up with a novel paint that could allow engineers to build lighter, cheaper and more elegant structures.

Vibration can produce fatigue cracks in structures like bridges and oil rigs that can lead to catastrophic failure. So engineers tend to make their structures more robust than they need to be.

The novel paint, developed by Jack Hale from the University of Newcastle upon Tyne, warn engineers when bridges are in danger of shaking themselves to pieces, a report in New Scientist said.

Hale’s paint is able to sense vibrations because it is loaded with a fine powder of a piezoelectric material called lead zirconate titanate (PZT). When PZT crystals are stretched or squeezed they produce an electrical signal that is proportional to the force. PTI

SCIENCE QUIZ
J. P.  Garg tests your IQ 

10. Some scientists think that this planet was originally not a planet but a satellite of Naptune which somehow separated away. Name this planet.

Answers

1. Havnes Alfvan 2. Gas in ionised state, such as in the interior of stars like sun; fourth state of matter 3. Liquid portion of the blood in which cells are suspended; immense number of ions, organic and inorganic molecules such as immunoglobulins and hormones and their carriers 4. Teak of sagwan 5. Angiojet Rheolytic Thrombectomy System. 6. A mixture of equal parts of basic lead carbonate and barium sulphate 7. Triple point; 273.16K and 610 Pa 8. Optic flow 9. Strontium 10. Pluto.