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Podcast TranscriptThe Naked Scientists: Science Radio & Science Podcasts |
| 7th Jul 2002 | < Previous Show | Next Show > | ||||||||||||
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Naked Truth About What's Living in your Garden
All sorts of creatures are living your garden that are never seen…mice and frogs and maybe even rats. But did you know that there could be up to 4 million different types of bacteria living in the soil, most not known to science? Researchers now think that there are more bacteria in a tonne of soil - the amount in the average garden - than in the whole of the world's oceans. Compared with the sea, soil offers a greater number of niches for bacteria to live in - for example, with and without oxygen - allowing many different types of bacteria to thrive. So instead of heading off to tropical rainforests to find new creatures, scientists would be better off digging up the back lawn. But they'll need some seriously sophisticated equipment, because these bacteria can only be detected using the same techniques used at crime scenes - DNA analysis.
7th Jul 2002
Lightning More Common in Cities
Cities attract 40% more lightning strikes than the surrounding countryside..and it's all due to the heat they emit. A 12-year study carried out in Houston and the surrounding countryside shows that the city area was hit by lightening, on average, 7 times a year, whereas in the countryside there were only 2 hits a year. The difference between the country and the city was more pronounced at mid-day in the summer and autumn. But why do cities attract lightning? The researchers from Texas A&M university have shown that this is not because the tall city buildings attract lightening, but because heat rising from the city buildings adds energy to storms overhead. This can turn rainstorms into thunderstorms. Air pollution from the many oil refineries in the region also adds to the problem. Particles emitted from the refineries attract water droplets to form clouds. This "lightning map" will help power companies find the right spot to put their transformers.
7th Jul 2002
Hedgehog Massacre
Bad news for hedgehogs living in the Western Isles of Scotland. These cute creatures are causing havoc to the local bird populations, and are now facing a cull. The Western Isles of Scotland are home to some of Europe's most important colonies of wading birds. But a recent study has shown that populations of snipe, dunlin, redshank and lapwing on the island of South Uist have declined by up to 60% over the past 7 years. However, on the neighbouring island of North Uist, populations of these birds are stable….and researchers from Scottish National Heritage lay the blame for this disastrous decline on the hedgehog. Four hedgehogs were introduced to South Uist in 1974 by a gardener, to control pests like slugs and snails. However, the hogs have been breeding like rabbits, feeding off the eggs of groundnesting birds, and over 5000 thousand of these small mammals are now living on the island. North Uist is not overrun by hedgehogs, which explains why it's bird populations are doing fine. The researchers think that a humane cull of the hedgehogs is the only way to save the South Uist birds.
7th Jul 2002
Cows Join the Genome Club
Cows have now joined humans, mice and sheep in having their genome sequenced. Metamorphix, a biotech company in Marlyland, US, have mapped the genome and are now scouring the sequence for genes that might make meat tender ! The company will let you have access to the code, but you have to pay them.
Article about the human genome project
7th Jul 2002
Gm Bugs to Conquer Tooth Decay
We told you on this programme 2 years ago how scientists were trying to genetically engineer bacteria that can stop tooth decay. Now a group of Swedish scientists have modified a harmless and common dairy bacterium, called Lactobacillus zeae, so that it produces antibodies against Streptococcus mutans; these are the bacteria that stick to teeth and churn out lactic acid that dissolves tooth enamel. Tests on rats have shown that a concoction of their GM Lactobacillus zeae once per week can dramatically reduce tooth decay. Don't hold your breath though - GM bacteria haven't been approved for use in humans yet, so this product might take a little time before it hits the supermarket shelves, although inventor Lennart Hammarstrom says that products like this will be the cheapest and best way to tackle cavities in the future.
GM (genetically modified) strawberries and apples to combat tooth decay.
7th Jul 2002
Chinese Hatch Space-chickens
Sticking with a space-theme, Chinese scientists in Beijing have recently been looking at the effects of space-travel on the development of chickens. Chinese researchers sent a clutch of chickens eggs into space for 7 days, during which they orbited the Earth over 100 times aboard the Shenzhou III space capsule. The eggs were then returned to the laboratory and hatched. The scientists are now looking for any genetic defects caused by the space travel and hope to breed from the chicks that they have reared so that they can study their offspring to see if any side effects are passed on. Naturally, if humans are to sustain themselves on long space journeys to colonise distant planets then an understanding of the impact of space travel on reproduction is critical, which is why this work is extremely important.
7th Jul 2002
Stone the Crows
Crows are well known for their intelligence, including abilities to mimic other bird songs to lure chicks out of nests so that they can eat them. Apparently crows living in Malvern have learnt to remove the blades from car windscreen wipers because they make ideal linings for nests !
7th Jul 2002
Online Passports Set to Arrive in Uk
As well as booking your tickets at the travel agent, you may be able to apply for your new passport by computer at travel agents in the future. The scheme is hoped to speed up the process of obtaining a new passport, as well as achieving the governments aim of making all of the governments services available electronically by 2005.
7th Jul 2002
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Why can birds sit on a power line and not be electrocuted ? Mary, Cottenham, phone |
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The reason that birds can sit unharmed on power lines is that no current flows through them because they are not completing the electrical circuit by sitting on one line only. Rather like water flowing down hill, electricity needs to flow down an electrical hill, otherwise known as a potential difference. So if you connect the plus side of a battery to the minus side current flows because there are lots of positive charges at the plus pole and very few at the negative, so the current flows to try to equal things out. So going back to the bird sitting on a power line, no current flows through the bird because it has the same charge as the wire it is sitting on. If it were to straddle a positive and a negative line, on the other hand, it would certainly be curtains ! Ditto if it put one leg on the ground and another leg on the wire. Under these circumstances there is a big difference between the amount of charge in the wire and the charge on the ground, so electricity would flow through the bird in an attempt to balance things out. |
July 2002 |
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Why does petrol and oil make a rainbow effect on water ? James, Email, Cambridge |
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This is because the oil spreads out to form a very thin film on the surface of the water, but of varying thickness. In some places it is literally a molecule thick, whilst in other places it is much thicker. When light passes through the oil some of it is reflected back off the different layers of oil, whilst some carries on and is reflected off the surface of the water lying below. Because the light waves have now travelled different distances before being reflected they mix together producing a spectrum of colours - because the thickness of the oil layer varies. For the super intelligent the light spectrum occurs because, having travelled slightly different distances, some of the waves are now 'out of phase' and cancel each other out, producing dark spots, whilst others add together, producing lighter spots. |
July 2002 |
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What is a mirage? Sally, email |
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A mirage is a trick of light seen in hot places like deserts (hence the association with thirsty travellers) and road surfaces. Like the end of a rainbow (another light trick) you can never actually reach a mirage. They form because when air is heated up light rays pass through it more rapidly, causing them to bend, or refract, upwards. They bend upwards because warm air close to the road surface, for instance, allows the light to pass through more rapidly than cooler air higher up, but when the rays reach your eye they are interpreted as coming from the road surface (like a reflection), rather than the sky, and so you see a mirage. |
July 2002 |
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