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Podcast TranscriptThe Naked Scientists: Science Radio & Science Podcasts |
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Son of Tsunami
The Boxing Day tsunami has several predecessors, scientists have found. Two papers in this week's Nature by Geoscience Australia researcher Amy Prendergast and team, and Kent State University Ohio scientist Katrin Monecke and colleagues have found evidence for at up to three previous massive tsunami events in the Indian Ocean. Both teams made their discoveries by taking core samples from marshy ridges behind the modern-day beaches in parts of Thailand and Sumatra respectively. The theory was fairly straight forward. Sudden large in-shore movements of water carry with them large amounts of sand and gravel which are then deposited uniformly wherever the water goes, covering the ground like a thin layer of icing. Over time these deposits are covered by soil and other materials as the flooded area recovers and returns to normal. But the gravel layers remain like "tsunami tide-marks" for centuries and can be pinpointed in time by carbon-dating material buried within the deposits and by other geological techniques such as looking at the rate at which the beach ridges have advanced. The teams found deposits consistent with up to three previous tsunamis including one likely to have happened in 1907 and for which there is a strong historical record. The other two occurred at around 700 years ago and the third about 1300 years ago. At the two sampling locations studied by the researchers the waves would have been up to 35 metres high when these events occurred. Previously there was thought to be no historical precedent for the 2004 tsunami; now we know differently. But what's still an issue, the researchers point out, is what this means to the people of Sumatra and elsewhere who live beside this threat.
References | |||||
| - Nature Geoscience 1, 777 - 781 (2008) | |||||
2nd Nov 2008
Nanotube speakers
Conventional loudspeakers work by passing a current though a coil near a magnet. The current creates its own magnetic field and so is pushed or pulled by the magnet. If you keep changing the current you will move the coil backwards and forwards creating vibrations in the air, and with the right set of currents, music. However, as you have probably noticed loudspeakers are large and unwieldy things.
Chinese researchers may have come up with an alternative. They have produced sheets of roughly-aligned 10 nanometre carbon nanotubes. They then applied an electric current to the fabric and sound came out. This was quite surprising so they tried to work out what was causing the sound. They shone lasers at the surface of the material and it appears that it isn't actually moving. What is happening instead is that it is heating and cooling from room temperature to 80 Celsius hundreds of times a second. This heats and cools the air close to it which causes it to expand and contract: creating vibrations and therefore sound.
This is not a new effect. It was first noticed over a hundred years ago by passing large currents though platinum foils. However, because it takes a lot of energy to heat up platinum it was immensely inefficient. It takes 260 times less energy to heat up this nanotube material by 1°C and it has a large surface area. As a result it efficiently heats the air and will work a lot better.
The material is transparent so it could be added to the front of an LCD screen on a phone and it is flexible so it could be placed on curve.
References | |||||
| - Nano Lett., 2008, 10.1021/nl802750z | |||||
2nd Nov 2008
Clever elephants have learned to avoid roads
Forest elephants living in West Africa's Congo Basin have learned to avoid roads probably because they realise that where there are roads there are poachers with guns.
That's according to a study published in the online journal Plos ONE, led by Stephen Blake from the Wildlife conservation Society. Blake and his team have shown that by avoiding roads elephants are confining themselves to smaller and smaller patches of habitat which could spell even more trouble for this endangered species.
The research team put collars on 28 elephants with Global positioning tracking systems and followed their movements through the forests of the Congo Basin. It became clear to them that elephants avoid roadways even in areas where poachers are kept out. During the whole study only a single elephant was recorded crossing a road and, when it did, it dashed across at 14 times its normal pace.
We might assume that if intelligent elephants have learned to avoid roads and poachers then this is a good thing because fewer of them will be shot.
But the problem is that the current book in road building is carving up the remaining areas of intact forest and the areas that elephants live in are contracting. It may be that elephant herds will not be able to find all the food and resources they need to survive.
There could even be a knock-on effect on the forest ecosystems since it is thought that when elephants roam large areas they play an important role in seed dispersal. This could be disrupted if they only live in small, separate patches of forest.
The good news is the research team have suggested that some relatively simple and cheap planning measures could be introduced that would make a real difference for the elephants. By planning exactly where roads go and trying to keep intact areas of forest that are as large as possible we should be able to minimise how much elephants continue to be confined by their fear of roads.
2nd Nov 2008
Hybrid camera helps to see in more directions
Digital cameras are brilliant at looking in one direction, which is normally what you want to do, but sometimes you need to see to the sides
as well.
The conventional solution to this problem is normally either to build a moving camera that can look in different directions or to use a fisheye
lens. This is a large, almost hemispherical lump of glass which will bend the light from the sides onto your camera. The problem is that these are
both large and heavy.
Insects solve this problem by essentially having thousands of separate lenses pointing in different directions: each producing one pixel of an
image. Previously this has been tried but it is difficult to make and you tend to end up with a very low resolution image.
Engineers at BAE systems have built a hybrid solution which involves about 9 lenses pointing in different directions. These focus light into a series
of optical fibres which bend the light onto a light-sensing chip. Software is then used to build up an image that makes sense. This means that you
can have a high resolution and see to the sides in an object about the size and weight of a sugarlump.
They are intending on using it first on missiles which can then hit a moving target more easily. But they say it could also be useful for
looking at confined spaces such as on the end of an endoscope used to look into body cavities.
2nd Nov 2008
Sabre-tooth tigers hunted in packs
Take a step back to the time when sabre-toothed tigers roamed the land. A new study has suggested these toothy predators were not lone hunters but may in fact have lived in packs like many social carnivores do today.
That's according to Chris Carbone from the Zoological Society of London and his colleagues writing in the journal Biology Letters this week.
The unusual thing Carbone and his colleagues did was to study modern day carnivorous cats in Africa to help understand what their ancient ancestors were doing thousands of years ago.
Ancient tar pits in Los Angeles, the Rancho La Brea, contain the fossilised remains of over 2000 sabre-toothed tigers: the cats had come to the tar pits to feed on prey that had got caught in the sticky tar. The researchers wondered whether all these cats came individually or whether they came together in a pride.
As a way of investigating this, they played back the recorded sounds of prey animals in distress both in the Serengeti region of Tanzania and Kruger National Park in South Africa. There were the same sorts of sounds that the sabre-tooth tigers would have heard thousands of years ago, from wailing prey animals trapped and dying in the tar pits. What they found was that the number of large social carnivores turning up to the recordings was much greater than would be expected based on the overall population size. Around 84 % of the animals that came to check out the noise were lions and hyenas, both social animals.
And the sabre-tooth tigers appeared in a comparable proportion at the Los Angeles tar pits. Along with another animal called the dire wolf, they made up the same 84% as was seen in modern-day Africa; hinting that they too are social and roamed around in gangs - a much more efficient way of scavenging for food.
So as well as being a rather ingenious way of looking in to the past, this study hints at the importance of links between scavenging and living in social groups: something that early humans may well have done just like the sabre-tooths.
References | |||||
| - 10.1098/rsbl.2008.0526 | |||||
2nd Nov 2008
Famine makes genes hungry for life
Scientists have uncovered the first clear genetic evidence linking low birthweight and maternal malnutrition and subsequent ill-health. Writing in this week's PNAS Leiden University researchers Bastiaan Heijmans and his colleagues describe how they have analysed DNA samples from babies conceived during the 1944-1945 Dutch war famine. This happened at the end of the Second World war as the occupying German forces blockaded food supplies to parts of the Netherlands. Consequently the population starved and many existed on fewer than 500 calories per day, less than 25% of what consitutes a healthy diet. Although the country was subsequently liberated and the population returned to good health, an interesting pattern emerged amongst the children conceived during the famine. These individuals have shown a tendency towards increased weight gain, diabetes and heart disease compared with their brothers and sisters who were born outside of the famine period. To find out why Heijmans and his colleagues focused their attention on a gene called IGF2, which is a growth factor, the genetic workings of which are very well understood. Specifically the team studied a pattern of chemical markers that can be attached to DNA to regulate gene activity rather like a dimmer switch. This is known as epigenetics and adds another dimension to the control of genes. The team were very surprised to find that the IGF2 genes of the famine babies had 5% fewer methyl groups attached to them compared with healthy controls and also their own siblings born at different times. "What is amazing is that we are still seeing this chemical effect more than 60 years - a whole lifetime - since these people were exposed to this insult," says Heijmans. "This shows that there can be lifelong consequences for a child due to the environment in which its mother lives." In other words, although famines are fortunately quite rare today, other maternal insults, like smoking, alcohol, drug use and other dietary deficiencies could have an irreversible epi-genetic effect on a developing baby...
References | |||||
| - doi: 10.1073/pnas.0806560105 | |||||
2nd Nov 2008
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Do tsunamis affect earthquakes?Is there any correlation to earthquakes on the west coast of the US with the tsunami activity in the pacific? Zanzibar Rothschild |
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Chris - There’s some suggestion that if you have big, seismic events in one place that you can encourage faults to be triggered in other places. On a global scale the answer is probably not because there are thousands of earthquakes happening around the world all the time. By the time the energy reaches an individual fault the chances are it’s probably largely diffused so it’s not sufficiently intense to trigger anything. Dave - I think it’s possible for one earth quake to trigger another earthquake which probably would have happened in the next year anyway. as one piece of rock is pulled across another at some point is is just about to slip, at this point quite a small vibration can make it slip. Chris - Presumably it’s geographically quite close. Dave - Yeah the closer you are the more likely it’s going to happen. I think there’s evidence it can happen the other side of the world but only on earthquakes which would have happened very soon anyway. |
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November 2008 |
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Glueing glasses
Stick two glasses together using the power of hot air.
What you need
| 2 identical plastic cups |
| Some Kitchen Towel |
| Some hot water |
What to Do
Make the kitchen towel wet with your hot water but don't scrunch it up.
Swish hot water around one glass and then lay the kitchen towel over the top.
Swish hot water around the other glass. Pour it out and place the second glass upside-down over the first.
Try picking up the top glass.
What may Happen
You should find that when you pick up the top glass the bottom one is stuck to it quite firmly.
What is going on?
When you heat up air its pressure increases, pushing the air around it out of the way so that it expands. When you swish the hot water around the glasses it heats up the air inside. This air expands and some escapes.
So you have slightly less air in the glass than was present at room temperature. When you let the air cool down its pressure will drop also. However, the glasses are sealed together with the damp paper and no more air can get in.
This means that the pressure inside the glasses is lower than outside and the glasses are pushed together.
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When the air inside is hot the pressure inside and out are similar, making it is easy to open. | As the air cools its pressure reduces so it is less than that of the surrounding air and the two cups are pushed together. |
This is the reason why it is so hard to open a new jam jar. The jam is put into the jar when it is boiling hot so air expands out of the jar and is replaced with water vapour. When the jam cools the air pressure reduces anyway and the water vapour condenses: reducing the pressure even more. It's the air pressure outside, pushing the lid on really tightly, making it hard to open.
Why does air pressure increase when you heat it up?
Air is a mixture of gases so it is made up of small molecules which are free to move. They are crashing into things all the time and in each of these collisions they push the object they have collided with back slightly. As there are billions and billions of air molecules all these tiny pushes add up to what we call air pressure. If you heat air up you give the molecules more energy, they move more quickly, collide with things more often and each collision is more violent. With hotter air the effect of all these collisions is greater, the air pushes on everything it touches harder and the air pressure goes up.
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A gas molecule hitting an object will bounce off and push the object back | If the gas molecule is moving faster the push will be larger. |
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Written by Dave Ansell
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How do you test for AIDS?I recently listened to one of your podcasts on AIDS and the possible vaccine based on plant proteins. One of the questions that intrigued me was if AIDS hides in our genome how do AIDS tests work? Mattea, San Francisco |
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Chris - You’re right. HIV, when you become infected with it, it infects a class of cells that have markers on their surface called CD4 cells. That can include white blood cells, macrophages and a whole other class of immune cells. Some of those cells become what’s called productively infected. So the virus goes in, hijacks a cell and turns it into a virus factory. Not all cells have that happening in them. In some cells the virus goes in, it doesn’t turn it into an immediate virus factory. What it does is it makes a DNA copy of the virus RNA and integrates that DNA copy or inserts the DNA copy of the virus inside your own DNA. Then it just turns off and so you have cells wondering around your body that contain HIV and they can turn on that HIV when they want to or when the signals are right for that to happen. To all intents and purposes they’re just a cell going about their daily business. How do you know that person’s got HIV? There are tests that we do in the laboratory to detect HIV are what’s called serological tests. One test will look for antibodies because although people don’t seem to become immune to HIV they nonetheless make huge numbers of antibodies against different parts of the virus. We run a blood test in which you take a sample of the patient’s blood and you present that blood sample with various proteins which are made synthetically but they’re based on what’s on the surface of a virus. They look for whether antibodies in the patient’s blood can bind or lock on to that surface with the viral coat on it. If that happens it means that it’s a reaction test and it goes positive and we can tell. Another way to do it is if people are just acutely infected, they’ve only just been infected with HIV they may not have made any antibodies by that stage. That sort of test would miss that. There’s another kind of test which looks instead for virus antigen. When the virus is growing in cells it’s producing lots of virus proteins which get spat out by cells and they go round the bloodstream. You can do various tests which do the reverse of the test I just described. They have antibodies on the surface of the test plate. Those antibodies grab out of the blood any virus proteins. You can then detect that they’ve been picked up and that gives you a positive. There’s two ways to do it. It’s all done indirectly by markers. There’s a third way which is actually doing it by DNA tests. You can take a sample of a patient’s blood and you can then do PCR – polymerase chain reaction – and you can try to amplify or copy virus DNA and it only copies if the virus is present. You can detect how much virus is there and you can detect virus that’s lurking inside your own genome. |
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November 2008 |
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Can electricity be conducted through moving water?Can you conduct electricity up a continuous flow of moving water? We’ve all heard the idea of someone peeing on the underground and getting electrocuted. Ripu Daman-Singh |
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Dave - You certainly can conduct electricity in a liquid. Whether it’s going to move fast enough to overwhelm the flow is basically you need a voltage. If you’re trying to make current flow opposite to the liquid you need more voltage to get the same current because there’s going to be more resistance. It’s effectively moving a lot faster. You certainly can get an electric current moving in a moving liquid. Chris - How fast does an electric current flow through a liquid? Dave - Normally in a metal it’s very slowly because you’ve got an awful lot of carriers. On average it’s moving a few millimetres a second. Chris - The effect is instantaneous because it’s like Newton’s cradle: you put charge in at one end and it knocks everything along and charge comes out the other end. Dave - The actual signal is moving at near the speed of light. In a liquid you should certainly get a Newton’s cradle push-along. You might need a little more voltage to get the same current though. |
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November 2008 |
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Why are some parts of rhubarb poisonous?When I was a lad I was told that rhubarb stems could be eaten but the leaves are poisonous. Why’s that? Paul Anderson |
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Helen - They contain something called oxalic acid. The reason it’s in the leaves is because it’s there to put predators (herbivores who come along and munch them) off. It’s not good for them and it’s not very good for us as well. You would have to eat an awful lot of it to actually kill yourself. The lethal dose: LD50 which is enough to kill off 50% of the rats that are given the dose of 375mg per kg of rat. That would equate in humans to around 5kg of leaves which anyone would believe is rather a lot. Yes. It’a problem. It acts through your kidneys. It’s a compound that actually interacts with metal ions and can form crystals and trigger kidney stones. That can be a problem. Symptoms include weakness, burning of the throat and mouth, difficulty breathing and if you’re really unlucky – a coma. Stear away from those rhubarb leaves I think is the answer. Chris - What I want to know is who discovered that you could eat the bit in the middle but not the bit at each end. Helen - So many questions on food. There’s the weirdest foods in the world that you’d never imagine. Someone, I think, tries anything.
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November 2008 |
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Some scientific friends of mine assured me that a bullet fired from a rifle held horizontally will hit the ground at exactly the same time as a bullet from a rifle held vertically, pointing at the ground.My question is about rifles and bullets. Some scientific friends of mine assured me that a bullet fired from a rifle held horizontally will hit the ground at exactly the same time as a bullet from a rifle held vertically, pointing downwards. Fair enough, I’m a linguist. I was rotten at science but that seems to defy common sense. Edwin |
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Dave - This is a mangling of quite a famous experiment. What the actual thing they should have told you is that if you fire a rifle horizontally and drop the bullet from the same place at the same time then they’ll both hit the ground at the same moment. Chris - So you’ve got a bullet in one hand, rifle in the other. You fire the gun at the same moment you let go of another bullet from your hand. The two bullets should actually hit the ground... Dave - At exactly the same time. If there’s no air resistance basically how fast you’re going horizontally has no relationship to how fast you accelerate downwards. The bullet which is moving and the one which is accelerating downwards both move at exactly the same speed. They’ll both hit the ground at the same time. If you take a gun and fire it straight downwards then the bullet’s going to come out of the gun at several hundred metres per second. It’s going to hit the ground far quicker than the one you fire horizontally. Chris - We did an amazing experiment at school which I remember to this day which shows how good this experiment was: the monkey and hunter experiment. We had a sort of blow-pipe with tinfoil across the end of the blow pipe which was making an electrical contact to an electro-magnet that was holding a tin can at a distance. A ball bearing was put into the glass tube. You blow down the glass tube so the ball bearing leaves the blow pipe, breaking the piece of foil in the process. Therefore it cuts the supply to the electromagnet. The tin can starts to fall at exactly the same rate as the ball bearing leaves the tube. If all things are equal, i.e. the can is being accelerated down by gravity at the same rate as the ball bearing is being accelerated down by gravity the two will hit each other. They always do. It’s called the monkey and hunter experiment because the idea is that the monkey is dangling in the distance on a tree and the person fires the gun. Assuming it takes no time for the gun discharge to reach the monkey. The monkey lets go of the tree and starts to drop at the same minute the bullet leaves the gun. Therefore the bullet’s falling and the monkey’s falling and they should still reach each other. It’s a very elegant way of explaining it. |
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November 2008 |
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What makes underwater animals glow? |
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Helen - Underwater animals glow a lot; much more than on land. That comes down to the fact there isn’t any light once you get only not very far down into the sea. They do tend to glow and it’s a chemical reaction. It happens in all sorts of different ways. Some creatures use a type of bacteria. Some creatures use their own chemicals which are then put together. It’s essentially something that a general group of compounds that we’ll call luciferins which naturally undergo a reaction with an enzyme that catalyses that reaction. That’s called luciferase. It turns luciferin into something called oxyluciferin which, at the same time, produces light. One of the reasons why light is important: it’s a good way of communicating in the dark .It’s also a good way of snooping in the dark. One of the most clever fish is something called a loosejaw fish which is a malacostade. They actually cheat because most of the light in the ocean that are created by creatures are blue or green. That is actually the light that can be seen down there mostly. The red lights get absorbed much earlier higher up in the water column. This creature called the loosejaw fish creates its own red light. Nothing else can see it because no fish really bother trying to see red light because there isn’t any red light down there. If you make your own red light and you can see it yourself then you’ve got your own secret sensor. Chris - It’s a spotlight so you can go searching underwater. Helen - It’s ingenious because they can see things, the prey they’re after don’t know they’re being looked at and they can see it. It’s really ingenious. Another thing, one of the glowing creatures is the jelly fish. One of the Nobel prizes this year went to three guys: Osamu Shimomura, Martin Chalfie and Roger Tsien who jointly were involved with the green fluorescent protein, GFP, which I think Chris you know all sort about in terms of the molecular world and what’s going on inside us. By attaching this glowing thing onto parts of anything you can put it under a microscope and see what you’re looking at. It’s a really ingenious thing which has been recognized by this Nobel prize. Chris - GFP is just a fluorescent protein that some animals make but they can grab ultraviolet rays and turn those ultraviolet rays into green light that we can see. It’s a clever protein that’s capable of doing that. |
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November 2008 |
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Radar that can distinguish between planes and turbines
Craig WebsterMeera - We all know that the world is running out of fossil fuels and the burning of these fuels is affecting our environment. So we have to run to renewable sources of energy. The problem associated with wind farms is that tall wind turbines that make up the farm are picked up by the radar used by air traffic controllers when they’re looking out for planes. They can’t tell if it’s a plane of a turbine on the radar system. As a result the wind farms can’t be built where aviation radar is nearby which severely limits the areas that they can be built. There could be a solution in the pipeline thanks to a new technology being built by engineering firm, Cambridge Consultants in the UK. I’m at their headquarters in Cambridgeshire with Craig Webster, head of clean technologies. How do the current radar systems work and why can’t they tell the difference between planes and turbines?
Craig - Currently the radars are designed to search across large areas for air traffic so they can control them. I think of it a bit like a spotlight where you’ve got to cover a very wide area with a strong, narrow beam that you sweep across a wide area periodically – once every four seconds. They detect an object and when an object is moving you can tell it’s moving by the presence of Doppler. We all understand as when a train goes past and you hear the perceived change in frequency. You get a reflection of a moving object and when you have movement you then say I have an object of interest which should be an aircraft. With wind turbines they’re also large objects that are all rotating and they have large – structures moving a bit like wings. Unfortunately what they do is they are seen at random. You have unsynchronized rotation and it’s a bit like a very slow strobe light. You see different positions of targets and it’s very had when an aircraft flies over the wind farm to tell which one’s an aircraft and which one’s a wind turbine. This uncertainty is an issue to the air traffic controller.
Meera - Does the fact that it checks it only every four seconds then add to the problem because it could be a quite a long amount of time that a plane ends up travelling over a wind farm.
Craig - Yes, in some of the examples that we’ve seen the air traffic controller loses control of the aircraft for a minute, maybe more. The uncertainty if they see something that they think might be an aircraft in a wind farm they have to manage the other traffic. They put separation distances – quite often it’s a five mile separation and if that wasn’t really an aircraft and it wasn’t really a wind turbine then that’s causing them some problems: it’s congested air traffic, it uses a lot of fuel. The converse side of that is if you actually didn’t detect an aircraft when there wasn’t an aircraft there that could be a safety situation.
Meera - What have Cambridge consultants come up with to try and solve this problem?
Craig - Well what we have is a radar that doesn’t scan so we’re able to observe the turbines in a way that we can actually measure the speed of the objects that are moving around where a scanning radar, the long-range air traffic control radars, just don’t get the opportunity to dwell on the target for long enough to measure its speed. They can say it’s moving but they can’t tell you how fast it is. Because we can see the speed we can easily tell the way an aircraft moves in a very different way to a wind turbine. If an aircraft is a speed, say it’s 40m/s and it moves 4m in 0.1 seconds (because that’s the measurement interval we have) we know that’s an aircraft. The wind turbine quite simply doesn’t obey the same rules so it has lots of speed – lots of Doppler coming from the wind turbine blades. But they’re moving. They’re moving in circles, the tips move faster than the centre. The blades bend and shift as the blades are loaded up. It gives lots of speed messages but it doesn’t actually go anywhere.
Meera - You say the main reason it can tell the difference is the main reason it can judge the speed at which object s are moving. How does it actually do that?
Craig - It’s a bit like the difference between the search light and the flood light. We have what appears like a low-intensity illumination of the entire wind far. This is illuminated all the time. You might look at this visually you would have time to make the measurements and make the observations. Because we know the speed we can quite easily discriminate be certain it’s not an aircraft and a wind turbine.
Meera - So essentially it is simply because you are constantly watching the area around the turbine. Where have you tested this so far?
Craig - We’ve tested a small-scale prototype in Norfolk. That test has shown very clear differences between a turbine. The next test which we hope to be doing in a few weeks’ time would be to take the same prototype and scale it up so that it’s big enough to include aircraft. We’ll be doing aircraft trials within the next few weeks. We feel this is going to be a really positive step for the wind industry to be able to see differences. This has never been done before.
November 2008
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Should you fill tires with nitrogen?A friend of mine was going to get new tires and the guy tried to talk him into getting them filled with nitrogen. I can imagine it might be advantageous to do that on a high-performance racing car but if would it make any difference in a passenger car and why? Cole |
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Dave - I think there’s a couple of reasons why it might make a subtle difference. One of them is that there’s a lot of oxygen in air that we breathe. Oxygen’s quite bad for rubber. It will cause it to break down and get brittle and crack. That’s going to reduce the elasticity of the tire and make it last less long and make it slightly less efficient. The other thing is that ideally you want a gas inside your tire which if it compresses then expands again it doesn’t absorb any energy. The ideal gas for that is what are called ideal gases. The best ones are mono-atomic gases like.. Chris - Argon, xenon… Dave - Helium would work probably because it would be quite cheap. It would escape very easily because it… Chris - It’s very small and would escape through the gaps in the rubber molecules. Dave - If you’ve got things like diatomic gases, things like nitrogen and oxygen then that’s slightly worse because they take more heat to heat up. They can’t just move – they can actually spin as well which is another way of absorbing the energy. Triatomic gases, things like carbon dioxide and water take even more energy to heat up. They are less elastic. Chris - Just on a more pedantic scale, Dave. Isn’t it that a nitrogen molecule weighs slightly more than an oxygen molecule also worthy of mention? If you pump just nitrogen into the tire the actual gas inside will weigh slightly less? Dave - It might have a minute effect. I think fundamentally that unless you’re doing a huge number of miles and really stressed about the efficiency increasing the pressure of your tires a bit more is going to have much more effect than filling them with nitrogen. |
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November 2008 |
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Why are there only antibiotics for bacteria and none for viruses? |
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Chris - It’s a very good question. The answer is that bacteria are single-celled organisms. They are living, alive and have a metabolism. Viruses are the ultimate parasite. They’re not really alive. They are an infectious bag of genes which are absolutely tiny. A flu virus is one ten-thousandth of a millimeter across and they’re so tiny that they do not have any f the machinery inside them to make new copies of themselves. They have to infect a cell in order to do that. That means you’ve got a problem because bacteria look totally different to our own cells so it’s fairly easy to make drugs and chemicals that will roger a bacterial metabolism and which will not affect our own metabolism. Because viruses have to prey on our own metabolism and they have to use our own cells to make copies of themselves it’s very difficult to find ways to discriminate between the virus and a healthy cell and therefore avoid side-effects. There are some drugs that can do that. The most famous is a drug called acyclovir, most people will know it as zovirax which you put on cold sores. This works because the drug is a special chemical which is activated only in the viral infected cell. The virus makes an enzyme which locks onto the drug molecule and it switches it on. It will not get switched on in any other cell and once the drug is switched on it forms a special DNA letter which when the virus incorporates it into its DNA it cannot make the DNA chain of the virus grow any more. The chain terminates the virus and stops the virus growing its own DNA. It’s very difficult to do this. This thing that researchers are now looking at is the possibility of something like RNA interference. This is where you make short pieces of genetic material which are the mirror image of the viruses own genes. By putting those into the cell they lock onto the viral genes and make what’s called double stranded RNA. The cells usually associate this with rubbish, junk or viral infection and they target them to the cellular equivalent of the wastepaper basket and It gets ditched. That’s how you can switch off viruses and cells. Our own immune system uses that strategy as well sometimes. It’s a key problem that we’ve been grappling with for a long time. That’s why we haven’t got a cure for the common cold, I’m afraid. |
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November 2008 |
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Are there any health effects from firing off lots of fireworks in a confined space? |
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Chris - There would be if you were to breathe in all the smoke. The way in which fireworks make their nice pretty colours is by exploiting an effect that Bunsen of Bunsen burner fame discovered about 150 years ago. The science of spectroscopy: he realized that when you look at something, say a distant star, you can work out what the chemicals are in the star because different chemicals absorb light and they produce light at specific fingerprint wavelengths. You can exploit that fact. If you heat up an element it will emit light in one wavelength. You can get different colours from each chemical. Each chemical has its own unique flame colour. You give the elements some energy by heating it up in a firework and it glows a pretty colour. To get those nice colours in your fireworks you have to put lots of metals in. Strontium’s a good choice for making red colours. Barium can make pretty green colours and so can copper salts. They can make greeny-blue colours. That’s how you get the colours. The problem is that all those things can be toxic in big doses. The reassuring thing is that Disney have done some studies where they have Disney World in Florida and Disney Land in California where they jettison thousands of pounds worth of fireworks in their displays. Over 20 years of doing this they have never detected any significant heavy-metal poisoning in their waters in the water features where they let their fireworks off. Cynics would say that’s because all the people at the fireworks displays have gone home with the heavy metals inside them. I didn’t say that – I just heard it! |
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November 2008 |
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Does time go faster as you age?I’ve noticed as I’ve grown older that time feels like it’s moving faster than when I was growing up. Is there any reason for this and what is it? Jared, Utah |
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We put this to John Wearden, Professor of Psychology, Keele The question posed is a simple question but it has a complicated answer and it’s not a thing that’s been researched in any great detain unfortunately. The commonest anecdote seems to be a kind of paradoxical statement about time where older people report that hours seem to drag but the months pass very quickly. In other words time seems to pass rather slowly when they’re experiencing it but in retrospect seems to have flashed past very quickly. How can this happen? The feeling that time passing – whether time’s passing quickly or slowly while you’re listening to me, for example, generally seems to be governed by the activities that occupy the time period. If you’re watching an exciting film, for example time seems to pass very quickly. If you’re in some very boring situation time seems to pass very slowly. SO when you look backwards over the day it seems very long when there are a lot of activities. Whereas if there are very few activities, particularly very few new activities, it may appear retrospectively very short. The time paradox in older people: both the slowness of time as experienced as it passes and the retrospective feeling that it’s flashing past may be caused by a general tendency for older people to have fewer novel life experiences than they do when they’re younger. That seems to account for both the apparently paradoxical aspects of time experienced in aging.
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November 2008 |
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Isn't this analogous to hand-cranked movie cameras... If the cameraman turned the crank too quickly when recording, "over-cranked", the film would be in slow motion when projected at the normal rate. Turning the crank too slowly, "under-cranking", would speed up motion when the film was projected at the normal rate. The internal clock slowing with age is analogous to "under-cranking" and causes the perception of time passing to speed up. - RD - 28th Oct 08
Hi Jarad, I've got a theory about this. Lets consider our opinions on the subject we held as six year olds. Our earliest memories go back to the age of 2, maybe 1.5 years, right? Lets say we were 2 years old when we started our "conscious life experience" clock. Since 6yrs - 2yrs = 4 yrs of memorable awareness, it could be argued all of us at the age of six, that the time span of 4 years is equal to a "Lifetime". Do you follow? The year I was six, spring lasted forever and summer vacation went on and on. Halloween would never get here, and "How many days 'till Santa comes?!". The chronological distortions we suffered were not due to impatience; they were truly long periods of time to endure. The year I was 6 (don't forget, 4 years = a Lifetime) represents 1 quarter of my whole life! That is 25%! So 25% of a six year old's "Lifetime" time, is represented by 1 year. Now I'm 42. It is already the end of October! This year is flying by so fast! But my chronological measuring stick is longer. 25% of everything I know about a "Lifetime" is spread over 10 years! I perceive 1 year as a 6 year old perceives 5 weeks. If there were a magic potion that kept me alive for 10000 years, I might perceive the last 10 years between my 9990th and 10000th birthday to whiz by as fast as a 15 minute coffee break seems to today. Mike - jysk - 29th Oct 08
Firstly on the perception of the passage of time, there's two sides to it: a) how fast time appears to be passing right now (typically fast if you're busy/enjoying yourself, slow if you're bored) b) how fast the past year (or other extended period) has gone Looking back, how fast the past year seems to have gone depends on how much variety you've had. If you've been stuck in a routine and doing little new, then last Christmas will seem like yesterday. Conversely if you've been on several holidays, quit a job, moved house, started a new job, had loads of variety in the new job, made lots of new friends, etc (ie lots of new stuff, lots of novelty) then last Christmas seems a lifetime ago. At age 10, 1 year represents 10% of your life so far. Aged 50 1 year is only 2% of your life so far. Therefore, it would seem inevitable that when you're younger, one year contains vastly more new and memorable experiences than when you're much older, and therefore the years don't appear to fly by to the same extent. Maybe we should measure age on a logarithmic scale to 'linearise' perception of time? - techmind - 29th Oct 08
To add to the mathematical ponderings of the two previous posts I would consider the fact that, in terms of brain function, every experience fed into the brain via the sensory system as well as all that input's 'digested'product, is stored and accessible to varying degrees. As experience mounts we occupy our aware presence weighing the current inputs against the experienced (the stored/remembered). The time this takes is not available to awareness of anticipation of future expectation. In childhood, much time is available to future anticipation and makes the present 'seem' to crawl whereas the older we grow the more the present is occupied relating the current input to the database -if you will- and inhibits awareness' access to the idleness of the blank state. Hope I made myself clear. - wannabe - 30th Oct 08
...and why does a return journey seem to take less time than the outward leg?
- chris - 31st Oct 08
would you clarify that Chris?
- wannabe - 1st Nov 08
Familiarity? The route is less novel on the return trip? Or, that outward journies are often full of anticipation and expection (and maybe some concern about the risk of being late). Time takes an age to pass when you're "looking forward" to something. On the return journey you're brain is reviewing, analysing and filing the days' happenings - so you're more likely to be lost in thought... and suddenly find yourself at the terminus station or front door! - techmind - 1st Nov 08
I would think the mechanism to be similar Chris, awareness perception being modulated by experience; childhood experience dealing with the size of the database being one variety, preoccupation during anticipatory experience in the present being another; conscious awareness after all is but momentary expression of states, be they sensory inputs at a given moment or the memory assisted processing of previous inputs and the modulation of either by the emotional system.
- wannabe - 1st Nov 08
It's all relative to a persons perspective! Time moves to us according to our perception of it. Like was said earlier, when you are young a set period of time, say a month, seems longer. This is because that a single month makes up a larger portion of your life then a month does when you are older. This carries on to the second question, a return trip seems longer only if you are less excited about the return trip. For someone that is more excited about getting home then leaving home, the perception would be changed so that the return trip would seem shorter. This of course carries to many things such as "Time flys while your having fun", or "a watched pot never boils". It's all in our perception of time and how we relate to the passing of it. Travis - mobile_bob - 4th Nov 08
My own theory is we are busier as adults! The older we are the more we take on - and we are racing the clock! If you go into a retirement home and ask the residents about their day they will complain that time goes so slowly - they have less to do than when they used to home their own homes, jobs or businesses, also having a social life. - Lynda - 9th Nov 08
For anyone who has to get up for work it seems maddening that the time between alarm clock going off in the morning goes much faster than the time before lunch or leaving off time!
- Lynda - 9th Nov 08
Nice one:) Do you remember how immortal you were as young. How time couldn't touch you, you had all the time in the world. And getting old? Uhuh, no way, not me. And then suddenly you wake up, slowly or fast, to the fact that you are... old. And all those nagging about you needing to get ready for your pension makes life into a new and horrifying picture:) Well, you're only as old as you feel, remember that. And although memory changes with age, as well as other priorities that doesn't mean you're dead, does it? But memory do change with age physically. And perhaps sense of time too? And then there is this awareness of 'times end' you get as you get old(er:) - yor_on - 11th Nov 08
By wilsonwilsonjr@comcast.net (the Guest below)
Sorry about the parsing "Name"; short on time.
My "knee jerk" observation is: 'We're close to the end of the toilet paper roll' Bigger circles O vs o take less revolutions; ergo, seems slower. Thank you, I was here all week, hope you tried the veal.
oh well....
But seriously tho folks, the way I've thought time going faster, at least in the last 5 years or so (now 59 y.o.), at least the way it makes sense to me, is:
"Ever take a long car trip to a destination you and your honey never been before? i.e., Las Vegas from Ohio about 2000 miles. You get on the Interstate, head west on I-40, you're excited, 16 hours later you're in Amarillo, Tx looking for an unfamiliar Interstate exit for a cloud 6. Next day you think you can drive on through to Vegas....well you make it to Flagstaff, Az tired and ready to sleep. Next day you finaly make it to Vegas and hope you have the energy to give Vegas all your money because it took longer than you thought to get to Vegas (it didn't look that far on the map did it) on top of that you missed that last exit you needed to exit because you're unfamiliar with Vegas area. STAY WITH ME NOW.... Now, you timed your money just right that you wanted to give Vegas 1 week later. Yawn, Up, get in the car, get on the Interstate east toward good ole Ohio. You're out of money, the time spent on the vacation has made you tired, hope you have enough energy to get home, why did you drive it anyway going through your mind...You don't stop at Hoover dam and a couple other places you stopped on the way to Vegas (been there seen that), you just wanna get home to relax. But, now on your way home you know all the exits to take so you just keep driving knowing which exit you're gonna exit to rest a little. And, (with your honey driving a little) the....Next.....thing you know you look down the road and see that last exit that takes you to your house where you can finally lie down and rest from the "fun" of Vegas.
HUH?
Moral?(no thank you):
At (pick an age over 55) - We've been, There! Yep, done that (a few times), and we have seen all the scenery along the way of this 'unknown' life. And we can see that last exit from here, and it's getting closer all the time.
ps.I was asked by a young man, "what's the worse thing about getiing old,?" Not thinking myself old (teenager/musician in the 60's you know), I replied, "Getting old".
(But I still don't need viva viagra)
- Time-Faster-Age - 10th Dec 08
I read all the blogs and theroy about why time seems to be moving faster, that it's all in the perception.. This may be true, but i seriuosly think, that its something more than that. I think its more scientific, maybe a time/ space thing, i dont know, im not a scientist, but just as a dog can hear sounds that humans cant. I think I can actually feel time, like a sixth sense, now Im sure, whoever is reading this may think im totally whacked. but ive been trying to anyalyze this for a while now.. there is something happening with time, i can sense it i can feel it. Can i explain it? Time is moving faster! even if i do nothing all day, the theroy says it should be a long day, but no, time moves for me, extremely fast. now i said for me, maybe its the way my brain processes time, either through the phisology of my make up or maybe im just nuts! but when i tell you that I feel it inside of me that time is moving faster, I know that something is truly happening, maybe too subtle for the average person to feel, but it IS happening.. ok im going to check myself into the looney bin now.. does anyone have the time??
TimeTrekker
- Rick - 14th Dec 08
This explanation is not correct. When I was a child, I had nothing to do all summer, i was bored every day and the summer felt like forever, also now, when I look back, it seems like it took forever. Now, I have a lot to do, many new experiences, and I have a feeling time is passing by at the speed of light.
- Kris - 29th Jan 09
Those of you who are 55 or older think about this. The 80's were 30 years ago...seem like yesterday to you?
- Connie - 2nd Feb 09
Not that age but I can say this. I'm timeless:) - yor_on - 10th Feb 09
Me too
- Chemistry4me - 10th Feb 09
Couldn't life seem faster because everything is faster. It used to take a week to travel 30km now only minutes. In the future it may only take an nanosecond.
- echochartruse - 2nd Mar 09
hi I say on this topic that not age..... - healthcoach - 27th Mar 09
I need a ticking-time bomb!
- Chemistry4me - 27th Mar 09
LoL....
- raghavendra - 28th Mar 09
Why has that spam still not been spotted?
- Chemistry4me - 28th Mar 09
No, the 80s was the day before yesterday. The 90s was yesterday. Can't believe its nearly 12 years since I started uni! I'm sure I was only 22 last week. - fishytails - 28th Mar 09
No, the 80s was the day before yesterday. The 90s was yesterday. Can't believe its nearly 12 years since I started uni! I'm sure I was only 22 last week. - fishytails - 28th Mar 09
Times always have present motion. We are not in a position to hold it. But many times we repent at present for our past did and keep worrying about future. If and if we could able to concentrate in present ur time shall never run faster or slower too.
- textilesinfomediarydotcom - 5th Apr 09
I absolutely agree with this view. The older one gets, their ability to process information slows down. While we're young, our brains are more able to analyze greater quanities of data, this activity fills up our time with more information to scrutinize. This would naturely have the effect of causing our preception of it's passage to slow down. Conversely, the opposite will happen as our brains become less efficient resulting in the illusion that time is speeding up.............Ethos
- Ethos - 13th Apr 09
I did notice this for sure and here follow reasons applicable to me I would guess. When I was young, the world was more simple virtually, I kept myself busy with real practical things, also at school the pace was slower, so time did exist for things I was busy exploring or doing, small periods of time flying excisted. Today, years later and especially since the 1990's things tend to speed up time. Busy with virtual stuff rather than using a spade, make time go fly by as your brain is more occupied as time passes rather than your body. In the military, marching up down the time passed slowly for me. Sitting in front of a computer, the time flies, or interesting stuff at work, the time flies. The more I feel I make a contrabution to work, the faster the time flies. Today large periods of flying time excists for me. That does not mean I actually accoplished more 24/7. Imagine this:All the AC/DC power of the whole world switched off for one year...I can imagine that year will slow down considerably, even if I went older.?? - Dr Guz - 1st May 09
Very little research exists on this subject, but it has been researched. The pervading wisdom points mostly toward the posts here that mention "novelty" of experiences. When young, most all experiences are new or unknowns. As we get older, we go through many routines each day that hardly require new input to accomplish, since the data already exists in our minds (kind of like autopilot). And after a certain age, we are capable of metacognition--thinking about our thinking. So, when something NEW comes along, we have enough experience behind us to 'create' a scenario in our mind that accomplishes the anticipated end from our own means). The novelty, that used to stretch our minds to create our own unique perception of experiences, has worn away and an internal routine has taken over. You would need to have an extremely life altering experience, see through someone else's eyes or lose your complete memory to experience the same kind of novelty as when quite young. Time isn't moving any faster than it was years ago, and your perception hasn't really changed either. It's just that your mind is too busy routing all of your past experience to make your daily routines flow--and sometimes become more efficient--to be able to allow your mind to basically 'surprise' itself anymore.
- Obstacles - 3rd Jun 09
My own take on this is that is not a matter of perception but a matter of consciousness. Consciousness is a kind of generalised awareness which takes into account our every day perceptions, our memories, our dreams, our sensory imput, our feelings or emotions etc. As children this generalised awareness is limited as we are still trying to form links between all of those everyday perceptions. Our general sense of the world is that is is fast and immediate.
See the whole discussion | Make a commentAn older person would have a more expanded consciousness and all processing would be through a matrix of linked preperceptions that would take longer, giving us a sense of the paced and the sedate. Effectively there is more time to think and thinking takes more time. - Shane Killeen - 12th Jun 09
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Is there a maximum temperature?Is there a theoretical maximum temperature? We’ve heard of absolute zero but what about the opposite? Is there an absolute maximum? Hitoshi, Japan |
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Dave - Absolute zero is because temperature is because temperature is effectively how much energy each individual molecule has. If you give them more energy it gets hot if take energy out it gets cooler. Because something can have effectively zero energy you can’t take any more energy out of it. Then you can have a minimum temperature. You can put in as much energy as you like but it becomes faster. There isn’t really a maximum temperature. Chris - Well let’s see if someone tries it in the future. We know that the temperature inside the sun is probably about 15,000,000 degrees with lasers to create fusion on the surface of the Earth some scientists are achieving something in the region of 100,000,000 degrees. |
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November 2008 |
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