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14th Oct 2007
Naked Science Q&A Show
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This week, we're taking on your science questions. We find out how cockroaches and ants avoid the heat in a microwave oven, how best to protect yourself from lightning and why a light box can save you from a SAD winter. Also, a table decoration inspired, radiation-resistant spaceship design to keep astronauts healthy, how the contraceptive pill hurts A lapdancers' looks and why penguins prefer to go fishing with their pals. Plus, in Kitchen Science, Dave explains how to make a detector for the Earth's magnetic field - a home made compass! But will it work in space? And what will happen when the Earth's magnetic field swaps round? We answer all these questions and more.
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Interviews
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Professor Rami Abboud, Ninewells Hospital and Medical School at the University of Dundee
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Chris Vallance
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Kitchen Science
Build your own navigational aid from stuff you could find in your kitchen.
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Question of the Week
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Do birds get more than their fair share of heartbeats?
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I was cycling on Frodsham marshes listening to your show on my ipod. The weather was disturbed - some clear sky and sunset, some rain and an intense thunder cloud. Having remembered your item on the chap who was struck by lightening wearing his ipod and realising I was in a very open exposed spot I wondered what the safest course of action would be. Would a cycle's tyres be sufficient to act as a Faraday cage assuming I didn't put my foot on the ground?
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The way a car protects you from a lightning strike is not because the tyres are insulating so the lightning can’t go through it. It’s because you’re surrounded by the steel body of the car which conducts electricity much better than you do. If lightning hits the car the current is going to want to go through the steel much more than it’s going to want to go through you, so the current just goes around you and you’re absolutely fine in the middle. This effect is called a Faraday Cage. If you’re sitting on a bike and you’re not surrounded by metal then the bike will probably make it worse because it will produce a very nice conductive path from your head, through your arms, through the bike and down to the ground very easily.
Rubber is an insulator, but even though the tyres are rubber, They’re only about 1 inch across and this means the voltage needed to put a spark across that isn’t very large. The spark has already jumped about 500m from the clouds to you through the sky. Another inch to the ground isn’t going to be too much of a problem.
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Why do cooked plums taste so bitter?
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We couldn't answer this on the show last time, so we asked you to help. This answer came from Colleen in Michigan:
Colleen suspects it’s to do with the breakdown of sugars that give that bitter taste. When you’re cooking the sugars at high heat you get non-enzymatic browning which occurs either through caramelisation or something called the Maillard reaction. That is an interaction of proteins and sugars. A free amino group of a protein reacts with a carbon-R group of a sugar, producing something called N-glycosylamine. This is unstable and is basically a downstream product. It breaks down into something called the melanoidins which can be bitter to taste.
The reactions are pretty complex, she says, and not well understood. So there could be lots of different reasons. That might be why cooking, she says, is so much of an art!
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Some people think I am weird (which is partly true of course) when I tell them that keeping my cell phone on vibrate if it rings I feel it in the opposite leg than the pocket that it is in. Whenever I get a call and feel a vibration in my left leg I have learned to reach in my right pocket for my phone and vice versa. Why does this happen?
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We here at the Naked Scientists wouldn't like to comment on whether or not Tommy is weird, but if he is, he's in good company! Our very own Dr Chris experiences something similar -
Chris: What I have got is, on the outside edge of each elbow, if I pinch the outer skin of my elbow I feel a pain on a strip of skin on my trunk (about, if I laid my arm down by my side, where my elbow would be on my trunk). I feel that hurting there too. On both sides. This is interesting. I think it’s a sort of miss-wiring of the nervous system and it’s got an embryological basis to it.
When the body develops you start off as this flat plate of cells and that then rolls up into a tube. It’s split up into segments a bit like a centipede. Well, we’re very similar, we have segments to our body. And some of those segments are specialised. Two segments produce arms at the top and two segments down below produce legs. They bud out from the body segment and they pull the nerve supply from that segment with them. You end up with a sort of extension of the nervous system down into the two limbs: upper and lower. That then goes into the nervous system and informs your spinal column as to what’s going on in that bit of the body.
It’s possible, I suppose that some of the nerves, as well as being connected to the hand and the spinal cord area encoding the hand, could also be rooted to the bit of the body that bulge came out of. I suspect there’s a sort of a crossover going on in his nervous system where something has not crossed properly and the nerves from one side of the body are triggering nerves for the other side of the body. So it’s a sort of referred sensation phenomenon.
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My compass points to North wherever I am on Earth, so what will happen when I go into space?
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This basically depends where you are in space. You may have played with a magnet when you were a kid with some iron filings on a piece of paper. You’ll have seen something that looks very much like the Earth’s magnetic field produced by a magnet. From a magnet it comes out of the North Pole and curves round in two big ovals and comes back upwards at the South Pole. We on Earth can’t see that field and so when we’re on the ground it’s going from the South Pole to the North Pole and so the compass points north. If you were right at the North Pole it would actually point straight downwards and if you were at the south pole it would point straight upwards.
Now if you were out in space you would have the same thing. So if you were above the equator it would essentially be pointing to the north. And if you were above the Poles it would be pointing straight up or down. The farther away you go, the weaker it will get so that eventually the sun’s magnetic field will overwhelm it.
So if you were to fly around the world in a geosychronous way so that you were parallel to the equator and going round at the same rate as the Earth, it should still point north-south. But if you were to do an orbit Pole-Pole, like some of the weather satellites do, would it get confused as it went over the North Pole pointing straight down at the North Pole and rotating over and over its head as you go round.Spaceships mostly they get their direction by looking at the stars. The North Star is always in the same direction so you look at where it is and you know which direction you’re pointing in.
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In my garden, which is quite exposed, I find spiders webs where there’s no access between point A and point B where they’ve made their web. I’ve even put cameras up to see how they do it and I just can’t catch them in the act. So how do they get across these big gaps to make these webs?
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Spiders produce a very light and floaty piece of silk from their spinneretts and just wave it out in the breeze. the wind will carry it away and if it actually sticks on to something a bit further away it can start building its web. It’s all a bit chancy really, it’s not a determined thing. Once that first little thin line has stuck on they’ll climb along it and reinforce that first strut. Then they actually use their own bodies and footsteps to measure along and count back to the middle of it to get to the central point. Then they drop a sort of plumb line using themselves as the weight. They’ll go down like an absailer down a cliff. They absail down that line to make a Y-shape and that is the scaffolding they’ll fill in with different patterns.
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I’ve been hearing recently that a study’s been done that shows ants survive in a microwave but I was wondering if it’s another urban myth like cockroaches surviving nuclear explosions?
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Someone wrote to us at the Naked Scientists recently who said ‘I found a cockroach crawling around in my microwave,’ and they said that just for fun they turned on the microwave to zap him. They opened the door 30 seconds later and he was still crawling around. So it seems some things can survive a dose of microwaves.
In a microwave oven the microwaves come out from the right hand side and they bounce off the metal of the far side. It acts like a mirror and it bounces backwards and forwards and they form what’s called a standing wave. You get areas of the microwave which are very, very hot; which have got very, very powerful microwaves and others with approximately nothing at all. There’s about 7.5cm between these hotspots. So you get about four or five hotspots in your microwave, depending on how big it is.
If an ant were in a hotspot it would just feel to them like they were in a very, very hot place. So naturally, they’d want to get away from it to somewhere cooler. They would just walk to somewhere cooler where they’ll feel a lot more comfortable: just sit there and be fine! It would be more interesting if there’s a turntable because it’s there to move the food through the hotspots all the time. The ants would have to keep walking round the turntable to avoid getting cooked.
So it’s not a myth after all. There was somebody who made their way into the newspapers for all the wrong reason and they didn’t survive, actually. They decided, in a rush to go out on a date, that they would put their head in the microwave to dry their hair quickly. Unfortunately they didn’t survive the experience but their hair looked great afterwards!
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After a week of lethargy as the daylight gets dimmer and shorter (which seems worse this year because we hardly had a summer worth speaking of) I've been contemplating getting a light box. Is there any research on this and do they actually work?
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There’s lots of research on light boxes that really do work. Lots of people have Seasonal Affective Disorder. It’s a real entity, we think it has a genetic basis. This is where people feel the urge to want to hibernate as soon as you go into Winter. As soon as the days start to get shorter, you don’t get enough sun exposure. Or if you have to work nights, it can make you feel really quite nasty and quite depressed. For people who have this it can be quite disabling. So scientists have found that if you get a light box which gives you lots and lots of light in the morning (morning seems to be quite important) it seems to make people feel better.
What’s the physiological basis for it? Well, you have a body clock in the part of the brain called the suprachiasmatic nucleus in the hypothalamus. It’s got about five thousand nerve cells that work like a genetic domino effect. One gene turns on a second gene which turns on a third gene and that turns on a fourth gene and that turns off the first gene again and the whole thing goes round in a circle. That’s how it keeps time. It needs to be able to reset itself because if you go abroad on an aeroplane you get jetlagged for a little while before it resets. Recently, in the last four or five years, scientists have found there’s a population of nerve cells in your eyes which see light which is at the blue end of the spectrum and they don’t actually show your brain what they’re seeing. They just tell your body clock what they’re seeing. They tell the body clock when it’s bright and when it’s dark and by doing that they can reset your body clock and keep it in time. By shining this extra light, scientists think that’s how you can rescue your body clock if you need to.
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My dad used to keep chickens and I’ve always wondered why the same chickens lay eggs all the year round when most birds are seasonal? Also, why they haven’t got bloodspots in them like most eggs have?
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Well, it’s actually all to do with selective breeding over thousands of years. Originally, if you get very old breeds of chicken, they are seasonal.
Over each generation people have been picking the chickens which lay the most eggs and trying to breed those chickens. And so after generation after generation, the period which they lay eggs for is longer and longer and longer until, I’m not sure, probably the last 200 years they got to the point where they had chickens which would lay eggs all year round. So now, chickens will lay eggs all year round.
Naked Scientist Dave Ansell used to keep chickens when he was growing up , and noticed that they would lay a lot more in the Spring than in the rest of the year. In the Spring you’d get 2 or 3 times more eggs than you would, say, in the Winter.
With regards bloodspots, lots of people discard eggs that have blood spots in them because they think they’ve been fertilised. But there’s more than one reason why you can have a bloodspot in an egg. As the egg is being formed in the oviduct, which is the part of the chicken which makes the egg, sometimes you can get a tear in the tissue or a leak from a blood vessel. This squirts a little bit of the chicken’s blood into the egg. It’s not harmful and doesn’t mean the egg’s been fertilised, it’s just a bit of blood. So that’s why you have bloodspots.
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How much would the level of the oceans rise if we emptied every car heating system, swimming pool, drinks container etcetera and all the places where we store liquids globally?
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Assuming everyone was storing maybe a cubic metre of water, (although some people have very big swimming pools most people maybe only have a little tank of water in the loft between four or five people). So with ten billion people we’d have 10,000 billion litres of water stored. If you work out the area of the Earth it comes out at about 100,000 billion square metres so maybe sea level would rise by about a millimetre.
The calculation is that every twenty thousand years or so enough water arrives from outer space to raise the level of the oceans about an inch. So, it’s miniscule against that.
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Would having a light in your bedroom that’s triggered by a timer so the light then comes on and gently wakes you up help beat SAD?
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Getting higher levels of light in the morning would certainly help to beat Seasonal Affective Disorder.
There was also an alarm clock made by researchers in America which was teathered to your brainwave patterns. When you are dreaming and at certain points during the night you tend to have REM (rapid eye movements), this means your brain is much more active than when it’s in deep sleep. If you wake someone up when the brain’s much more active then they feel much better and come-to much quicker than if you wake them up when they’re in a deep sleep. So with this clock which you set the ideal time to wake up, and then it follows your sleep pattern and wakes you up based on you brain activity as close to your ideal time as it can.
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Why do Jack Russell dogs sometimes run on three legs with a hind leg lifted?
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Where is the safest place in a wood or a forest to run in a thunderstorm?
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Well, you might think that standing under a tree is a really good idea because then the tree will get hit by lightning rather than you because it’s a much better path than you are. The problem is that sap tends to heat up, turns to steam and then explodes, so you get bits of tree flying off and they can hit you and do more damage than possibly even by being hit by lightning itself.
Also the tree is behaving as a wonderful lightning conductor and this is raising the the electrical potential of the ground around the tree. Animals like cows and sometimes horses are found dead in fields because the electricity flows over the ground. It’s easier for the electricity to go up the cow’s front legs, along its body and down its back legs, killing it in the process, than it is to go across the ground. At least some of the electricity does. So you could still get taken down by electricity spreading away across the forest floor.
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I have a question about the reversal of the Earth’s magnetic field. I hear that the field polarity occasionally switches round periodically so the north turns to be somewhere south. I’ve also heard that between the switch there’s a period of time when there isn’t a substantial magnetic field so, my question is, what is the historical estimate of how long it would be before the magnetic field returns?
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The Earth’s magnetic field does seem to flip every few hundred thousand years and we’re overdue for one at the moment. A few years ago they thought this would take hundreds of thousand of years for it to flip slowly. But recent evidence suggests that it’ll maybe flip over faster. In the process of it flipping over it doesn’t tend to flip over evenly. What tends to happen is the North Pole gets weaker and weaker and sometimes you get two, three or four other North Poles around the Earth in different places that move around quite fast. Eventually it’ll stabilise again the other way around… maybe after 20-30 years.
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Are humans the only animals on Earth the only animals on Earth that secrete mucous from their noses?
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No, we’re not. Lots of creatures do have sticky noses and it’s all about protecting yourself from those things you might be breathing in. Basically it’s a layer of stickiness to catch dust and, more importantly, viruses that might invade your delicate mucous membranes. Things get breathed in and whirled around in your nose like in a miniature dyson vacuum cleaner, and then they get flung to the sides where you’ve got these sticky walls. Then you blow your nose and get rid of it, or swallow it so it gets broken down in your stomach.
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