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Podcast TranscriptThe Naked Scientists: Science Radio & Science Podcasts |
| 27th May 2006 | < Previous Show | Next Show > | ||||||||||||||
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Belly Bulges
Have you ever wondered why some people eat exactly the same food as their friends but seem to put on more weight? Researchers at Washington University in Missouri, US, think they may have found the answer - it's not pies, but something a great deal smaller. The team have been studying a type of bacteria in the gut called Methanobrevibacter smithii that live in the gut. The bugs help to clear up the waste products of other gut bacteria, such as Bacteriodes theta, that break down components in food that our gut enzymes cannot digest. The team found that mice carrying both types of bacteria in their guts were on average 15% fatter than mice that just had the theta strain of bugs. The researchers think that the smithii bacteria help the theta type to thrive and grow, so they can produce more fatty acids from undigested food. These fatty acids are taken up by the mice and turned into fat. Around 85% of humans have the smithii bacteria in their guts, and we get about 10% of our calories from fatty acids made by microbes such as B. theta. However, we don't yet know if overweight people have more smithii bacteria than underweight people, but the researchers are working on finding out.
27th May 2006
Watch Out For Black Holes!
Sometimes it's hard enough thinking about space-time in just four dimensions - x, y, z (the dimensions of space) plus time, as laid out by Einstein in his general theory of relativity. But scientists at Duke and Rutgers Universities in the US are working on a mathematical model of the universe that has five - x, y, z and time plus another spatial dimension. They call this model "braneworld", because it suggests that the visible universe is a membrane, like a "strand of filmy seaweed" floating in a larger universe. But how do we know which model is a more reliable representation of the universe? Such models make predictions about the nature of space, and in the case of braneworld theory, it predicts that our solar system should be peppered with several thousand small black holes left over from the early universe. In contrast, the general theory of relativity says that these black holes should no longer exist. Because black holes are essentially undetectable, we have to hunt for them by looking for their effects on radiation waves that go past them. Radiation from events such as gamma ray bursts en.wikipedia.org/wiki/Gamma_ray_burst <http://en.wikipedia.org/wiki/Gamma_ray_burst> can be bent by the gravitational pull of a black hole, and we can detect this so-called gravitational lensing. At the moment, we don't have enough evidence of gravitational lensing to say whether there are black holes in our solar system or not. But over the next few years, space scientists will be launching a satellite telescope that will be able to detect any changes in gamma ray radiation, so scientists will hopefully know which mathematical model is the most accurate representation of the universe.
27th May 2006
Science Update - Fish Libraries and cell division
Chelsea Wald and Bob Hirshon
Kat - Now we're going to hop across the ocean for this week's Science Update. We've got Bob Hirshon and Chelsea Wald primed and ready to tell us about a digital fish library and how we can turn back the clock in cell growth by reversing cell division.
Bob - This week for the Naked Scientists we'll be talking about scientists who have hit the rewind button on cell division. But first, it's not uncommon these days to hear of libraries going digital. That can mean scanning millions of pages, but what do you do if instead of books, your library consists of animals?
Chelsea - In museums and institutions around the world, vast collections of animal specimens are just gathering dust, but not for much longer at the Scripps Institution of Oceanography at La Jolla California. It's home to one of the world's biggest fish libraries and a team there is about to embark on a new project to scan the fish and put them online. They're using MRI, magnetic resonance imaging, which is commonly used by doctors to look inside the body without ever making a cut. As radiologist Larry Frank of the University of California San Diego explains, scanning fish with MRI will allow scientists to do the same thing.
Larry - Here is an image of a shark brain. you can see that we've been able to separate all the different components: the olfactory lobes, the eyes, the nose. Here is the same object from a dissected specimen. You can see that they're essentially the same. This was done completely non-invasively.
Chelsea - This is especially useful for rare specimens that lots of people want to study but are difficult to replace. It's also good for seeing things in situ, like the small fish that curator Phil Hastings points out inside the belly of one of the first fish they scanned.
Phil - We're actually getting an image here of two different fish. One has been eaten by the other one.
Chelsea - They hope that the digital fish library will offer opportunities to make new discoveries to everyone from university researchers to secondary school students.
Bob - You can check out their progress on www.digitalfishlibrary.org. Also in the news recently, for the first time scientists have performed a feat that was once thought as impossible as un-ringing a bell. A team led by molecular biologist Gary Gorbsky at the Oklahoma Medical Research Foundation reversed the process of cell division.
Gary - And specifically the end stages when they're actually divided in half. We've been able to reverse that process and go from the stage where you have two cells back to the stage where you have a single cell.
Bob - He says they turned the clock back by tinkering with proteins that regulate cell division. This worked only when the divided cells hadn't completely finished separating. The implications aren't clear yet, but the technique could be useful for cancer researchers who are always looking for ways to keep rogue cells under control.
Chelsea - Next week we'll talk about some paranoid birds who go to great lengths to hide their belongings. Until then, I'm Chelsea Wald.
Bob - And I'm Bob Hirshon fro AAAS, the Science Society. Back to you Naked Scientists.
May 2006
The Science of Well-being
Professor Felicia Huppert, Department of Psychiatry, University of CambridgeChris - What are you going to be talking about when you go to Borders on Wednesday?
Felicia - The science of well-being. There's an enormous amount of interest at the moment in happiness and we're going to broaden this out an talk about the fundamental science that underlies all this interest.
Chris - So why people want to be happy, as opposed to being sad.
Felicia - Exactly, and that's an important part of it. Up until now, medicine and psychology has always been focussing on the problems people have and disorder and dysfunction. But it's time to start asking questions about what makes people well and what makes them feel good. And there are a whole load of different things that make people feel good and we need to try to understand.
Chris - What are nature's feel-good factors then, Felicia?
Felicia - Well I'll come back to that in a second. Feeling good is important because it makes us function well and this is why we talk about the science of well-being as opposed to just the science of happiness. So what makes people feel good? It turns out that, not surprisingly, friends and family are incredibly important. Knowing your strengths and utilising them; being really engaged in the things you do, and actually doing things for other people. These all seem very key.
Chris - So it almost seems as though the good Samaritan was something we were programmed to do. Why is it good for us to have friends, sing in a choir, go to church, play a musical instrument or say our prayers? All these things have been proven to help people live longer. Why should that be a fact?
Felicia - We evolved as social animals and so presumably in a part of our evolution, those of us who had good friendships and worked for other people were the ones that were more likely to survive in hard times. That stayed with us.
Chris - Animals are the same aren't they?
Felicia - Absolutely right, yes. There are a lot of social animals and there are other animals that are less so.
Chris - In insects such as ants, wasps and bees, they might not as far as I know experience sensations of pleasure, but they must get some sort of reward from helping each other.
Felicia - Yes.
Kat - So recently David Cameron the leader of the Conservative Party made a speech saying that we need to be happy and we need to think about general well-being rather than money in the pocket. If you were running this country, how would you go about increasing general well-being?
Felicia - I think you can do it at various different stages of the life course. I think we should start very early because the evidence from animal research is that how you nurture very small animals makes an enormous difference to their mental health and their capability throughout the rest of their life. So we need to focus on those early years to make sure that parents know how to bring that child up in a way that maximises their physical and mental health. In the school years, encouraging children to learn about social and emotional intelligence is really very important. It increases their own well-being and increases the chance of them having friends. There is a lot of evidence too that if you are feeling positive, you perform much better in every aspect of your life. You concentrate much better, you generate more ideas and are more resilient in a stressful situation. You bounce back much faster and these are all very good reasons. At the other end of the spectrum, because I'm quite interested in older people as well, one reason why older people may not function as well as possible is due to our negative stereotypes of aging. If in our society we could make people more positive about aging, and there's experimental evidence for this, if old people feel more positive they are more confident, their memory and learning is better, their numerical skills are better, and their stress reactivity is better. So by feeling confident you get into this upward spiral where everything is better. So at every stage in the life course I think there are things we could be doing in our society to improve well-being generally.
May 2006
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If sound and heat are both vibrations, then why isn't sound hot and heat loud? Dylan via email |
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They are essentially the same thing. Basically heat is happening on a very very small scale: if you imagine the heat waves and the wavelengths of the vibrations are very small and about the same size as a normal atom. However with sound, the wavelengths of the vibrations are a few centimetres. So in a sound all the atoms are moving in the same direction close to each other. Eventually the vibrations of sound will start breaking up and moving off in random directions and it will convert into what we feel as heat. Dr Hugh Hunt, who appeared as a guest on the show last week, provides this reply: 'Sound is vibration of the air and the ear is designed to detect air vibrations, but only over a small range of frequencies from 40Hz to 20kHz. Heat is vibration associated with the motion of photons and our skin is good at detecting a certain small range of frequencies of photons. Light is like heat, but our eyes are optimized to a different small range of frequencies. So our senses are all very specialized. All waves carry energy from A to B. The energy that our ears detect we call sound. The energy that a light bulb produces we call heat on our skin and light in our eyes. So it is all arguably down to language: hotness, loudness, brightness - they are all simply alternative names for the energy level. |
May 2006 |
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If someone has an amputation, do they get high blood pressure because there's less body space for the blood to move around in? Peter in Essex |
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What we usually find is that they have lower blood pressure, paradoxically. If you lose, say, a leg, then there's less blood that needs to be pumped out of the heart and into the main blood vessels in order to get it around the body. You obviously have a big chunk of your body missing and it doesn't need any blood, and so your heart is doing less work. As a result, your blood pressure tends to drop a little bit. If you have people who've lost both their legs, they often have lower blood pressure because they've got fewer areas of tissue that need to be reached by the blood and so the average blood pressure in the vessels is lower. |
May 2006 |
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If everything on the planet got wiped out by a bomb, could life start again like it did originally? Pat in Lowestoft |
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I think you'd have to try really hard to wipe out life. There's life thriving in the most inhospitable places on our planet including right down in the deep ocean trenches, in hot vents and volcanoes. I think it would be pretty impossible to wipe out life. Over the last few years people have found bacteria living kilometres down in solid rock, so you'd have to vaporise a couple of kilometres of rock. The best example must be the huge meteorite several kilometres across slammed into the Earth about 60 million years ago. It dispensed with the dinosaurs but not crocodiles, which were around at the same time as the dinosaurs. It meant the certain animals were set back a long way but meant that animals like us, mammals, began to flourish. It gave us our big break in life. So perhaps if we did decimate the Earth with a bomb, then maybe another funny form of life would take over. |
May 2006 |
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If you hold your lips closed with your fingers and breathe out as hard as you can, and then release your fingers, you blow out a puff of smoke. Why is this? Jeff via email |
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You have to do this in a fairly cold room. When you compress a gas, they got hotter. You'll have seen this when you pump air into a bicycle tyre and the tyre gets hot. Conversely, if you expand the gas, it'll get colder. So What I think is happening is that when you squeeze all the air into your mouth, it's compressing and heating up a bit and absorbs some water from your mouth. When you let it out again it gets colder, and when it gets colder it can't hold as much water in it. This is exactly the way clouds form. Clouds go up and contract as the air gets colder. The water comes out and forms a cloud. |
May 2006 |
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Do you think we'll ever beat the speed of light? Nelson in Norfolk |
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As far as we know, we probably can't. With everything we currently know, the closer you get to the speed of light, the more energy you need to go a little bit faster and you'd need an infinite amount of energy to go at the speed of light. But that isn't to say that something might not change as we learn more and more. The amount of kinetic energy something has normally equals m (mass) multiplied by v (velocity) squared. As you get faster and faster, there's another component going in which is inversely proportional to the speed minus the speed of light. So as you get closer to the speed of light it gets closer to infinity. So as you get faster you notionally get bigger so you need more energy to speed you up. As you get faster and faster, that tends towards infinity. As far as we know, there's no way to bypass that unless the world doesn't work quite the way we think. |
May 2006 |
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Why do some people suffer so badly with static electric shocks? It's particularly bad when I get out of my car. Neil in Felixstowe |
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The whole planet is engulfed in a dense blanket of air molecules and as your car drives along it has to push those air molecules out of the way. The reason a car makes a noise as it goes along is because it's creating turbulence and making air molecules bash against each other and the car and that sort of ripples away. What this means is that static charge builds up on the car because it's isolated from the road. This is because most cars have rubber tyres and rubber is a good insulator. It's a little bit similar to when you have a storm cloud and want some lightning. You've got lots of water molecules and little ice crystals called hydrometeors. The wind currents inside the clouds bash these things around and as they slowly rub against each other they transfer charge. You end up with a cloud that has one charge at the top of the cloud and the other charge at the bottom of the cloud and that's why you get a lightning bolt. So it's sort of doing a similar experiment with your car at road level. When you step out of the car, the car body carries a charge and you are connected to the ground. You are also isolated from the car and so when you then touch the car to close the door, then the charge difference between you, the ground and the car neutralises itself using you as the vehicle by which to do that. People who wear rubber soled shoes will get these shocks worse than people who don't because you can't earth yourself to the ground as well. |
May 2006 |
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When I take a painkiller, how does it know where the pain is? Morris via text |
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When you take a pill like an aspirin or a paracetamol, what it does is to target the inflammatory cascade. What that means is that if you have an injury to a part of the body, you start to make substances in those parts of the body that signal to nerve cells that that part of the body is hurt and that you shouldn't move it around too much. The way the painkillers do it is they block this cascade of inflammation everywhere in the body at the same time so that anywhere that is hurting doesn't hurt as much. So it's not that it homes in purely on you headache; it has its effects everywhere in your body. But you only notice its effects where you had the pain before because it stops being so bad in that area. |
May 2006 |
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I learnt in school many years ago that food takes 12 to 24 hours to travel through the body. As I've got older, out-gassing has become a more noteworthy part of my life but it doesn't appear to adhere tot his time schedule. When I eat flatulent foods such as beans or something like that, I become very gassy in a little as one to two hours. Why is this? Where in our gut do these vapours form and how do they get out so quickly? Dan in New York |
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The average human produces between half and one and a half litres of flatulent gas every day. This is partly oxygen and nitrogen that we've swallowed when we eat. But partly it's things like gases that are produced by microbes in our guts. We know that bacteria make these gases. Food passes from your mouth into your stomach and then into your small intestine within about one to two hours of eating it. It then takes five or six hours to get through your small intestine and then twelve to twenty four hours to get through your large intestine and colon. Most of the bacteria that make these smelly gases hang out in your colon, but some especially gassy people have a lot more of these bacteria in their small intestines further up the intestinal tract. This is probably what Dan is finding. The bacteria are getting to work on the food much quicker and so he's probably finding that he's getting gas much quicker than other people. |
May 2006 |
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When people measure carbon dioxide, a lot of the time it is measured in weight. They'll say that your car releases so many pounds of carbon dioxide. But how do you weigh a gas? Drew in Seattle |
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Everything here on Earth is made of atoms and molecules and they must all weigh something. Since we know how much each of these individual atoms and molecules weighs, it's very simple to say that because we know how much gas came out of the car and how much of each gas was in it, we can work out how much the carbon dioxide weighs. That's the simple argument. Now to put a bit more complexity into the argument, chemists have a very clever measurement called a mole. This is a convenient measure by which you can compare directly how much of something you've got. One mole of any chemical substance contains 6 followed by 23 zeros atoms. So if you have one mole of carbon dioxide, you know you've got 6 followed by 23 zeros molecules of carbon dioxide. We know how much one molecule of carbon dioxide weighs and we know how much one mole of carbon dioxide weighs. One mole of carbon dioxide weighs 44 grams. The average person is said to produce through their lifestyle about 4.5 tonnes of carbon dioxide every year. So you could say that four and a half tonnes is about 4400 kilograms of carbon dioxide, or 4.4 million grams of carbon dioxide. I told you that one mole of carbon dioxide weighs 44 grams, so if you divide 4.4 million grams by 44, that means you must have ten to the power of five moles of carbon dioxide that you've made through the year. We know that one mole of gas takes up 24 litres at room temperature and pressure. So if you times 24 by that, that means the average person produces through their lifestyle, 2.5 million litres of pure carbon dioxide gas every single year. That's half the size of a large swimming pool, which is a considerable amount of gas. |
May 2006 |
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Why doesn't nature make any straight lines? Brian in Norwich |
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Well it produces crystals and beams of light, which travel in straight lines until they hit something. Crystals are probably the obvious example of something solid that is made with straight lines. If you look at a salt crystal it will have flat faces and the corners will be sharp. The corners will be in straight lines because of all the little atoms that stack in a big pile. |
May 2006 |
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We kept Friesian cows for about fifteen years. Sometimes they got sunburnt but only on the white patches. Why? Ian in Northampton |
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White hair is basically transparent whereas a black hair is dark. The light will go straight through the white hair and straight through to the skin. However in black hair it will be absorbed by the hair. |
May 2006 |
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If you have oil on the surface of a dirty pot and you add washing up liquid, why is it that all the oil shoots to the side? Stephan in New Zealand |
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Well it's exactly the same as what you heard in Kitchen Science this evening. The washing up liquid disrupts the surface tension and makes the oil shoot across your pot. |
May 2006 |
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Matchstick Boats and Surface Tension
Build matchstick boats that will zip across a water surface, just powered by soap.
What you need
| A bowl of water |
| A couple of matches |
| Some soap or washing up liquid |
What to Do
Fill the bowl with water just a cm or so is fine
Gently float the matchstick on the water.
Place a tiny drop of washing up liquid near the matchstick, it is easiest to do this with another matchstick.
What may Happen
You should see that the matchstick zips away from the washing up liquid as soon as you drop the washing up liquid on the water.
What is going on?
This all comes down to surface tension. If you imagine that you're a water molecule right in the centre of a tank of water, water molecules have an attractive force between them so you'd be being pulled in every direction by all the water molecules around you, all these forces would cancel out so you don't move.
Now if you imagine that you're a water molecule at the surface; you'll be being pulled in every direction from the side and from below but you're not being pulled from the top at all because you've just go air above you there. So what would be the effect on you? Well you might find that you're being squished down a bit and you end up with a more dense film of molecules on top of the water. So water is allways being pulled together, which is why water tends to clump together into droplets.
Water molecules are also attracted to other substances such as wood, glass or paper, so a matchstick for example will be pulled by the water wherever it is touching it.
Washing up liquid is a surfactant, which is something that breaks down surface tension. So by adding washing up liquid, one side of the matchstick has the attraction between the water molecules broken, whereas on the other side of the matchstick they're still attracting each other and the matchstick.
So what the matchstick feels is a pulling force from all the molecules on the clean water side, but on the other side there is virtually no surface tension. So rather than being repelled by the washing up liquid, it's actually being pulled from the other side across the bowl of water.
Written by Dave Ansell
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