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Podcast TranscriptThe Naked Scientists: Science Radio & Science Podcasts |
| 11th May 2002 | < Previous Show | Next Show > | |||||||||||
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How Do Birds Navigate and How Do People Have a Sense of Direction ?
Scientists found a few years ago that migrating fish, like Salmon, that unerringly return to the same river year after year to mate, have deposits of an iron-rich compound at the front of their head. These iron crystals pick up the Earth's magnetic field, almost like an internal compass, allowing the fish to navigate. Now scientists have found that people too may be sensitive to the Earth's magnetic field, possibly explaining how birds and other migratory animals know where to go. Unlike Salmon we don't have iron deposits in our heads, but it is thought instead that we might be able to unconsciously 'see' Earth's magnetic field, helping us to navigate. To test this idea a team in Leipzig, Germany, led by Dr. Franz Thoss, measured the lowest level of light that volunteers could detect in a spot shone straight ahead of them. They found that when they shone the light at the same angle as the Earth's magnetic field, in other words so the light and the magnetic field followed the same path, the volunteers could detect a much dimmer light than when they were facing in other directions. The effect was very small, but nonetheless significant, say the researchers, who think that the magnetic field alters the way the light-sensitive (photo) receptors in the retina work so they become slightly more sensitive when lined up with the Earth's magnetic field [J. Comp. Physiol. 188: 235].
11th May 2002
You Should Have Fruit Juice with Lunch, Not Breakfast
Why have fruit juice at lunchtime, rather than breakfast? Fructose, the fruit sugar, is rapidly absorbed and increases blood sugar levels quickly, thereby stimulating insulin production. As a result of the insulin the blood-sugar level falls and there is a surge of low-density lipoprotein fats released by the liver. These fats are not artery-friendly. The effect of a heavy dose of fructose is greater at breakfast time than later in the day, for the body's metabolism is not the same throughout the day; hence fruit juices are better taken with lunch than breakfast.
11th May 2002
Plan to Use Genetically Modified Carp to Solve Overpopulation in Australian Rivers
European Carp species are taking over Australian rivers and streams and driving out native varieties of fish to the extent that scientists are planning GM warfare to kill off the invaders. The problem has become so bad that now 90% of the fish stocks in Australia's Murray-Darling river system are European Carp. The plan is to use gene technology to stop the carp from producing any female offspring, causing the population to plummet. They intend to do this by making some genetically modified male fish in the lab which contain multiple copies of a gene called daughterless which makes carp produce only male offspring. (daughterless is an altered version of the 'aromatase' gene involved in metabolism of the female hormone oestrogen). By introducing these GM fish into the wild periodically, slowly the population will all become male and so the population will collapse. But the scientists must first demonstrate that their plan is environmentally safe and will not create more problems than it solves and so they are currently testing the idea in the lab on small, fast-growing zebrafish.
11th May 2002
Mouse Genome Unveiled
Scientists can now add mouse to the list of animals which have had their genetic blueprint decoded. The work was done here in Cambridge at the Sanger Centre, where the human genome was mapped, and at several centres in the US. The work shows that mice have about 30,000 genes, which is about the same number as humans, and people and mice share about 75% of their genes. Mice have slightly fewer chromosomes than us though - we have 23 pairs, but mice have only 20. We should add that the mouse genome has already been sequenced by a private company in the US called Celera, but researchers have to pay to read the sequence. The new sequence from the Sanger centre will be free for everyone to use.
Article about the human genome project.
11th May 2002
Referees Go with the Crowd
As world cup fever hits the nation, a researcher from the University of Wolverhampton has confirmed something that football fans have long suspected - that referees are swayed by the crowd. Alan Nevill found that the shouts of angry fans can put the referee off penalising the home side. A home game can give a team a big advantage - and Nevill wanted to find out why. He showed a group of qualified referees video footage of tackles from Premier league football matches. Half of the group could hear the crowd, but the other half listened in silence. Nevill asked them to judge whether a foul had been committed or not. And guess what - 15% less tackles were judged to be fouls when the sound was on. This could go a long way to explaining why teams are more successful when playing at their home ground.
11th May 2002
New Weather Forecasting Satellite
Accurate weather forecasting, even with supercomputers, relies on getting a detailed picture of the atmosphere at any moment in time and then predicting what the air will do next. Measurements are taken using weather balloons, remote weather stations, ships and buoys. By the time data are collected into a model things have unfortunately already changed. Forecasters typically get tomorrow's weather right 85% of the time - but when asked what's going to happen in five days' or a week's time their accuracy falls to 55%. Dedicated weather satellites are already in orbit, scrutinising our atmosphere, but the resolution of their sensors is quite coarse - tens or even hundreds of kilometres. This week a new weather and climate satellite called Aqua launches from Cape Canaveral in Florida, USA to kick off a new age of weather monitoring. Placed into what's called a polar orbit 700km up - it will stay in the same point in space relative to the Sun, and look down on the whole Earth turning beneath every day. Its battery of sensors will measure infrared and microwave radiation as it leaves the Earth's atmosphere - translating this into detailed vertical temperature and moisture profiles through the air, and tracking the global water cycle accurately. Meteorologists (the weather experts) hope that Aqua and other next generation weather satellites like the new Eumetsat, due for launch in August, will make long range weather forecasts more accurate and improve predictions of how and why our climate seems set to change.
11th May 2002
Male Starlings Sing a Song of Reproductive Fitness
Scientists at Johns Hopkins in the US have found that how well a male Starling sings is a strong indication of the health of his immune system and hence his suitability as a mate. Dr. Duffy and Dr. Ball looked at the singing abilities of 16 adult male European Starlings in an outdoor aviary. They compared the strengths' of their immune systems with how many songs they sang, and how long each song was. They found that they best singers also had the best immune systems. Presumably female Starlings pay a lot of attention to singing because it indicates a healthy mate who is likely to father healthy chicks. How the link between immunity and song quality comes about though, we don't know, but as the researchers point out, it might provide important clues to how the immune system is controlled at large which has implications for many diseases in animals and people.
11th May 2002
Clever Magnet - Plastic and Light Sensitive
American researchers have developed a magnetic plastic that changes its magnetic strength depending upon the colour of the light shining on it. When blue light is shone on the material it nearly doubles the strength of its magenetic field, an effect which the inventors think is due to the molecules of the substance changing shape when light of a certain wavelength hits it. They suggest that the new material might be useful for storing computer data.
11th May 2002
Railways Will Need a New Excuse for Lateness
"Your train has been delayed because of leaves on the line" says the crackly British Rail announcement. This problem causes havoc for rail commuters, and cost Railtrack £60 million in 1999. But it could be a thing of the past thanks to a sci-fi invention to blast leaves from the track. Former naval officer Malcolm Higgins has devised a laser gun to scour railway lines of leaf slime, and a prototype of his invention will be tested in the autumn. Inspiration hit Malcolm, who doesn't travel by rain and isn't a scientist or engineer, when listening to a radio news commentary about leaves on the line.
11th May 2002
The Naked Truth this Week
Last week we revealed the truth about beer bellies - this week we turn our attention to another bane of life, and reveal the shocking truth about red wine stains. What do you do when you spill red wine on your cream carpet? Let me guess - you rush to the kitchen and splash white wine all over the stain and then add piles of salt, because we all know that this is the best way to remove red-wine stains. But is it? Well, no! A young scientist in America spent weeks dipping different fabrics in red wine to find the best stain removers. She found that white wine and salt just didn't work - considering that salt is used as a fixative for dyes, this is hardly surprising. So next time someone knocks a glass of Burgandy over your favourite cream trousers, try liquid soap and a mild solution of peroxide - they're scientifically proven to work. The research also revealed that silk was by far the most awkward material to get stains out of. So now you know.
11th May 2002
Self-inflating Football to Boost your Game
Whenever your football goes a bit flat, your game suffers because you can never find the football pump. Now scientists in the US have invented the world's first soccer ball with a self-contained pump. Using computers to analyse the dynamics of a football in play, scientists worked out the best shape and construction materials for the pump. It's taken nearly a year but its makers are confident that their football is now indistinguishable from other balls in professional use.This new football has received approval from FIFA and should be in the shops by June 2002.
11th May 2002
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