SCIENCE TRIBUNE Thursday, September 26, 2002, Chandigarh, India
 


A blow fly --- the most reliable witnessFlies help in solving crime
Devinder Singh
"A
murder by slashing occurred and the village headman tried his best to solve the crime. After some fruitless questioning he had all the menfolk bring their sickles to a common place and lay them out before the crowd. Flies were attracted to one of the sickles, probably because of smell from invisible remnants of blood and tissue still adhering to it in spite of all the attempts to clean it. Confronted by this indisputable evidence the owner of the sickle broke down and confessed to the crime.

A blow fly ó the most reliable witness

Chips for sensing bioterrorist agents
R
esearchers in the University of California have fabricated dust-sized chips of silicon that could detect a variety of biological and chemical agents, including substances that a terrorist might dissolve in drinking water or spray into the atmosphere.

Indiaís fastest supercomputer
T
he Bhabha Atomic Research Centre (BARC) has developed a new supercomputer for much faster solution to computation problems in a range of fields, including scientific research and simulation of nuclear explosions.

 
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Flies help in solving crime
Devinder Singh

"A murder by slashing occurred and the village headman tried his best to solve the crime. After some fruitless questioning he had all the menfolk bring their sickles to a common place and lay them out before the crowd. Flies were attracted to one of the sickles, probably because of smell from invisible remnants of blood and tissue still adhering to it in spite of all the attempts to clean it. Confronted by this indisputable evidence the owner of the sickle broke down and confessed to the crime.

The aforesaid is an actual incidence that took place in a Chinese village during the 13th century and is one of the earliest application of insects in solving crime. This branch of science that deals with the use of insects as forensic evidence is now-a-days called Forensic Entomology. There are large number of laboratories throughout the world where research concerning this fast developing field is going on and the author had the privilege to work for a year in one of such prestigious laboratories in the University of Illinois at Chicago, USA.

Entomologists in the developed countries not only go the courts for testimony as expert witnesses, but are also hired by the prosecutors and defenders just like lawyers. Hundreds of cases have already been solved substantiated by insect evidence. Forensic Entomology is a favourite topic these days for documentaries often seen on TV channels like Discovery, Animal Planet and National Geographic. On the top of it, famous detective agencies like the FBI of the USA have employed entomologists as special agents and they are involved in routine investigations about crime.

The central dogma about the use of insect evidence lies in the fact that decaying bodies of animals (including that of man) are attractive to various kinds of insects. The latter have an acute power of smell and they are the earliest to find a dead body, often before the police do. The blue and green beetles are the most important of all the communities to initiate the process of carrion colonisation. They lay eggs on the decomposing body and the emerging maggots are voracious feeders. These crawling creatures reduce the body to hair and bones within few days. Various kinds of other flies and beetles are also associated with carrion degradation.

One of the primary elements during a murder case is to establish the time of death as accurately as possible. There are several methods for its estimation when there is a gap between actual death and time when the body is found. All the techniques like histological, chemical and bacteriological means are helpful only if the dead body is a few days old and miserably fail when the time since death is more than a week. Entomological approach remains the only plausible method under such circumstances.

Interpretations about insect evidence are based on the ecological concept of succession. The invading insects that feast on an exposed corpse come in a sequence of waves. The first wave of scavengers brings about changes in the cadaver by removing the soft tissues and making it more attractive to the next wave of invaders that prefer dried skin, bones and cartilage. There are two ways for the application of entomological data to determine the post-mortal interval (PMI). During earlier stages of decomposition it can be estimated by the time required for a species to reach the stage of development when recovered from the corpse at the time of discovery. The most advanced stage of development that in turn shows the longest period of association with the corpse will represent the minimum PMI. In simple words if five day-old maggots are found from a decomposing body, the latter canít be less than five days old. After the early stages of decay have lapsed, estimates are generally based on interpretations of insect succession patterns because arrival and departure time of various kinds of carrion insects is predictable for a particular area.

Insects and their immature stages found on a decomposing body may also provide some hint towards the probable mode of death. A body having external injuries is more attractive to insects than one having none. So depending upon the degree of degradation brought about by maggots, an entomologist may be able to suggest the mode of death e.g. strangulation or mutilation. Another application is in cases where death has occurred due to the intake of drugs. A chemical analysis of the maggots found on the dead body will reveal the presence of specific drugs, particularly important in cases where no human tissues are available for investigation.

The deceased may have died at a place other than where the body has been found. With knowledge about the carrion fauna of an area and the specific rural or urban, indoor or outdoor habits of the species found on the cadaver, it is possible to determine the place of death. If immature stages of a species not belonging to the local carrion fauna are found on a dead body, it indicates that the body has been brought from a different area. Even the route of transport in several cases was traced using entomological data.

There are innumerable other situations where help should be sought from entomologists. Insects found in association with the narcotics of plant origin can suggest the place of origin of the drug. If the body is found buried in soil the insect data can help to determine the period intervening death and burial. Large numbers of civil cases have also been solved using insect evidence and it will not be out of place to narrate one of them. A woman admitted in unconscious state to a hospital in Chicago was discharged after four days. At home her son noticed maggots coming out from her nose. She sued the hospital because according to her flies laid eggs in her nose due to the negligence of the staff when she was admitted in the hospital. The hospital administration was confident about their innocence and they engaged an entomologist. When the maggots were studied in the laboratory, they were found to be six days old. Hence it was proved beyond doubt that the lady had the maggot infection when she was brought to the hospital.

However, a thorough knowledge about the carrion fauna of an area is required for the use of insects in forensic investigations. Lot of potentially useful evidence is going waste in our country due to the lack of this base-line data. The Department of Science and Technology has already made a beginning in this direction by sanctioning a major research project to the author. Our team at the Department of Zoology, Punjabi University, Patiala has been able to generate the data required for use of insects as evidence this region of the country. Forensic Entomology must get due recognition in India as well because there has been an increasing emphasis on scientific investigations while the third degree methods are on their way out.
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Chips for sensing bioterrorist agents

Researchers in the University of California have fabricated dust-sized chips of silicon that could detect a variety of biological and chemical agents, including substances that a terrorist might dissolve in drinking water or spray into the atmosphere.

The development is likely to have wider commercial use in research and medical laboratories ó in performing rapid biochemical assays, screening chemicals for potential new drugs and testing samples for toxic materials.

As the technique permits rapid detection of biological and chemical substances remotely, using a laser similar to a grocery scanner, it can also be employed as an advanced warning system for biological and chemical attacks.

"The idea is that you can have something thatís as small as a speck of dust with some intelligence built into it, so that, it could be inconspicuously stuck to paint on a wall or the side of a truck or dispersed into a cloud of gas to detect toxic chemicals or biological material," says Michael J Sailor, a professor of chemistry and biochemistry in the UCSD, who headed the research.

"When the dust recognises what kinds of chemicals or biological agents are present, the information can be read like a series of bar codes by a laser similar to a grocery store scanner to tell us if the cloud coming toward us is filled with anthrax bacteria. Itíll alert us if the tank of drinking water into which weíve sprinkled the smart dust is toxic," he said.

The "bar code" on the silicon dust particles is basically a specific wavelength of light or colour, reflected from the particle surfaces after thin films layered on the silicon chip chemically react to a specific chemical or biological agent.

Scientists start with silicon wafers similar to those used in making computer chips, then, "encode" these by generating layers of nanometer-thick porous films on the wafers using a special electrochemical etch, the report says.

This layered structure on the dust-sized particles, that are created by breaking apart the wafer using ultrasound, imparts unusual optical properties to the particles. Referred to as photonic crystals, these micron-sized particles are able to reflect light of precise colours, each one of which can be thought of as a single bar of a grocery-store bar code.

"When youíre looking for chemical or biological warfare agents, youíre going to want to search for thousands of different chemicals," says Sailor.

"Since the particles can be encoded for millions of possible reactions, itís possible to test for the presence of thousands of chemicals at the same time," he adds.

The other researchers involved in the development were Fridirique Cunin and Thomas A. Schmedake, postdoctoral fellows in Sailorís laboratory; Jamie R.Link and Yang Yang Li, graduate students in Sailorís laboratory; Sangeeta N. Bhatia, an associate professor of bioengineering in the UCSD; and bioengineering graduate student Jennifer Koh. The project was supported by the Defense Advanced Projects Agency (DARPA).

The encoding that takes place in these particles provides colours that are so sharp from the visible to the infrared that a laser can read thousands of distinct colours corresponding to separate chemicals.

In this way, these coded particles can perform thousands of biochemical assays in a small beaker or a Petridish, which should be useful in many medical and research applications, such as the discovery of new drugs, the diagnosis of various diseases and the controlled release of therapeutic drugs.

"An advantage of the method is that porous silicon is biocompatible and the use of these encoded silicon nanostructures in medical diagnosis may be significantly better than other methods that involve the use of potentially toxic materials, such as heavy metals," says Cunin, the first author of the paper.

Unlike grocery-store scanners, that typically must read bar codes only inches away, Sailor and his group have been able to get their laser to detect the colour changes in the smart dust 20 metres away. UNI
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Indiaís fastest supercomputer

The Bhabha Atomic Research Centre (BARC) has developed a new supercomputer for much faster solution to computation problems in a range of fields, including scientific research and simulation of nuclear explosions.

The computer division of the BARC has developed the ANUPAM-PIV 64-node supercomputer with a sustained speed of 43 giga flops (floating point instructions per second).

It has a speed three times that of its 2001 version and 1000 times faster than the BARCís first 4-node version of 1991.

"The ANUPAM-PIV is 30 to 40 times faster than the parallel computer developed indigenously by other institutes in the country and more than 10 times faster than the fastest supercomputers imported from abroad for various computing applications," the Head of Computer Division, H.K. Kaura, said in Mumbai.

Supercomputers are extensively used for solving very large computational problems in scientific research, engineering, industry, defence and business for a variety of applications such as molecular dynamics, simulation of reservoir, simulation of collision of galaxies and crash studies for automobile, aeroplane and nuclear weapons.

The latest Cray SV1 supercomputer imported for weather forecasting applications by the National Centre for Medium Range Weather Forecast (NCMRWF) of the Department of Science and Technology has a sustained speed of about 4 giga flops.

"ANUPAM-PIV is designed using Pentium IV personal computers operating at 1.7 GHz with 256 MB memory each, and the computing speed is expected to improve further with the use of the recently acquired ultra-fast communication hardware based on Scalable Coherent Interface (SCI), IEEE standards in place of the fast Ethernet switch (which is currently used)," Kaura said.

So far, the Computer Division has commissioned 37 earlier designs of the supercomputers in the BARC and other leading institutions like the Aeronautical Development Agency (ADA) of Bangalore, Vikram Sarabhai Space Centre, of Trivandrum, IIT Mumbai and Kanpur, the UDCT and the SNDT womenís university in Mumbai and the NCMRWF in Delhi.

ANUPAM series of supercomputers, according to Kaura, features a high supercomputing speed at a very low cost. It is also highly reliable and user and environment friendly. PTI
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NEW PRODUCTS & DISCOVERIES

Digital voice changer

If you fancy scaring the hell out of someone, while remaining totally disguised, then this is the gadget for you.

It has six voice changing options, and digitally changes your voice frequency to enable you to remain totally undetected. The fun possibilities are endless.

For fewer pet allergies

Young children raised with cats and dogs are at much less risk of developing common pet allergies, according to a US study in The Journal of the American Medical Association.

"We simply started looking at our data to see if exposure to dogs and cats really increases the risk and the data didnít look the way it was supposed to; as a matter of fact, it was very strongly the opposite of what we expected to find," said study co-author Dennis Ownby, chief of the Medical College of Georgia Section of Allergy and Immunology.

Over a period of seven years the researchers compared 84 children exposed to a minimum of two dogs or cats to 220 children whose families had no such animals.

They discovered 15.5 per cent of children in families with no cats or dogs developed cat allergies, 50 per cent more than the 7.7 per cent of those with two or more cats or dogs.

The same results proved true for dog allergies, with 8.6 per cent developing the allergy in households without dogs and cats, versus only 2.6 percent in the other group.

"The bottom line is that maybe part of the reason we have so many children with allergies and asthma is we live too clean a life," Ownby said. "What happens when kids play with cats or dogs? The animals lick them. The lick is transferring a lot of bacteria and that may be changing the way the childís immune system responds in a way that helps protect against allergies," the doctor said. AFP

New anti-depressant awaited

US psychiatrists will be able to prescribe an eagerly awaited new anti-depressant called Lexapro. Itís being promoted as more potent and possibly safer than older competitors but thereís little evidence that itís much better.

Still, Lexapro promises to be a big player in the $12 billion US antidepressant market. So, how do patients and doctors choose whether to try it or another of the bewildering array of depression drugs?

"Youíre playing the odds," is the blunt way Philip Ninan of Emory University puts it: Each anti-depressant comes with a different set of pros and cons, and thereís little way to know in advance which will work best for which patient.

With potential breakthroughs so far away, any new option causes excitement even if, like Lexapro, the drug isnít very different chemically from its predecessors. Indeed, Lexapro is a fine-tuned version of the popular drug Celexa, the latest in the Prozac-spawned class of "selective serotonin re-uptake inhibitors," or SSRIs .

The Food and Drug Administration cautions that Lexapro hasnít been proved superior to any antidepressant. But in a 491-patient study, 10 milligrams of Lexapro once a day worked as well as 40 mg of Celexa. A few patients felt better about a week sooner than Celexa users.

And while Lexapro causes the same side effects seen with most SSRIs ó from nausea and sexual disfunction to insomnia and daytime fatigue ó about 5 per cent fewer Lexapro users experienced them. AP
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SCIENCE & TECHNOLOGY CROSSWORD

Clues

Across :

1. It has a plasma membrane as its boundary.

8. Place where birds perch or rest.

9. Length of a bridge between its supports.

11. Ö.maker is an electric device to stimulate hear muscle.

12. Straight line joining ends of an arc.

13. Heavy, costly and durable timber.

15. A lens whose surface is made up of a large number of smaller lenses to produce short focal length lens.

16. Symbol for Aluminium.

17. Abbr. for Embryo transfer technology applied to cattle, sheep and pigs.

18. Abbr. for Ground water table.

19. Symbol for Protactinium.

20. Female sheep.

23. Substance used for rubbing or scrapping off.

25. Short for engineer.

26. A tall narrow structure to support transmission lines.

Down:

1. Siliqua fruit belongs to this family.

2. Semi-solid sour food prepared from milk and fermented by added bacteria.

3. An instrument that measures the frequency of tones.

4. Abbr. for a unit of measurement of liquids in USA & UK.

5. Black semi solid sticky substance.

6. Ö..gap, the space between two electrodes across which the discharge of electricity takes place.

7. ÖÖ number gives the ratio of speed of body to speed of sound in surrounding medium.

10. Luminous or dark patch in sky made by distant star cluster or gas.

14. Abbr. for sophisticated electric machine used to record movement of nerve cells in the brain.

16. Tail less monkey.

21. Plastic substance secreted by bees.

22. An ever green tree.

24. Symbol for Bromine.

 

Solution to last weekís
Crossword:


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