Published: Wednesday 15 October 2003

simple remedy: Garlic not only keeps the vampires at bay, but also pests such as slugs and snails, which cause millions of dollars worth of damage in countries with cool or temperate climates. Scientists from the uk-based University of Newcastle upon Tyne have found that the pungent herb could act as an ecofriendly pesticide. They assert that garlic adversely affects the creatures' nervous systems. They believe oils in the herb are the active component but they do not know whether they are acidic. The odour is thought to be what repels the pests. But the researchers add it is unlikely that gardens or crops in which the garlic oil is used would end up reeking.

weekend blues: Researchers have found that, in many places, the temperature range between the daily high and low changes on the weekend. And, as with some people, there seems to be a little hangover of this weekend effect on Mondays. Piers Forster and Susan Solomon of the US-based National Oceanic and Atmospheric Administration noticed the 'weekend effect' while studying 50-year records in an effort to learn about global warming. About 35 per cent of the locations under scrutiny experienced a significant 'weekend effect'. The change can either be due to increased human activities, or as a result of pollutants causing changes in wind circulation patterns on a weekly basis.

roaring downfall: Research has revealed the lion population of Africa has undergone a dramatic decline over the past 20 years. A report by the US-based University of California states there are just 23,000 lions left on the continent, down from around 200,000 in the 1980s. Rosie Woodruff, a biologist with the university, says that wildlife parks are not an answer to the problem. They are just not big enough to support a healthy population. The only solution is for people and lions to learn to live together. The scientists, who have spent the last seven years studying the interaction of human and animals in central Kenya, believe it can be done quite successfully.

better than the best: Researchers from Trinity College, Ireland, have evolved a technique that significantly improves the output of light from quantum dots (the most efficient light-bulb in the world); it also allows their light to be focussed and manipulated easily. The researchers embedded the quantum dots (tiny particles made from semiconducting materials) on the surface of a microsphere and enhanced the output of light by a factor of 20. Because the surface was spherical, it allowed the light to be focussed into a fine beam that could be moved around easily.

genetic means: Pine trees near the Chernobyl nuclear plant in Ukraine have altered their DNA in response to the 1986 accident. Trees that received the maximum radiation doses died. But those exposed to smaller doses survived, suggesting they found ways to tolerate the radiation. To test this theory, Olga Kovalchuk from the University of Lethbridge in Canada, with Andrey Arkhipov and Nikolai Kuchma from the Chernobyl Centre in Ukraine, planted Scots pine seeds in sites full of radioactive debris. When the trees were 10 years old, they measured the levels of methylation, a process regulating gene expression in plants. It also protects essential genes from damage. The scientists report that there was 30 per cent more methylation activity in the trees than their counterparts growing in a clean area.

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