What's Inside Your Nappy?

Do stars form outside galaxies? What causes ringing in the ears? How fast does force propagate? Why do spectacles still work when worn backwards? Is the expanding universe tearing...
08 January 2012


Do stars form outside galaxies? What causes ringing in the ears? How fast does force propagate? Why do spectacles still work when worn backwards? Is the expanding universe tearing galaxies apart? And is any new water being created on Earth? Plus, news of the new satellite surveying the moon, the scientific way to sound out a Stradivarius and how a vaccine based on chimp viruses can protect against Hepatitis C. Plus, in kitchen science, Dave unpacks the contents of a nappy...

In this episode

X-ray diffraction pattern of crystallized 3Clpro, a SARS protease. (2.1 Angstrom resolution).

- Explosive X-ray diffraction

A new method of determining the structure of a crystal has been developed which can measure the structure even though it causes the samples to explode...

Explosive X-ray diffraction

One of the major ways of discovering the structure of molecules, particularly complex ones like proteins, is X-ray diffraction.  This involves firing a beam of X-rays at a crystal and "reading" the pattern that the reflected x-rays produce.  This is possible because crystals contain repeating molecular units, and so X-rays reflected from the crystal produce a distinct pattern that can be used to identify the structure of the molecule.

However, to decipher a large molecule you need to use very bright X-rays, which can damage the sample.  This damage can create uncertainty as to what the original structure was.

X-Ray diffractionIn a bizzarre twist, scientists from the Center for Free-Electron Laser Science in Hamburg may have reduced this problem by making the X-rays brighter - much brighter.  They use an X-ray laser which produces X-rays a million trillion times more intense than sunlight.  They only fire the laser for 30 femtoseconds, or 30 million billionths of a second, but in just a fraction of this time the sample absorbs so much energy it violently explodes.

You would think this explosion would invalidate any results, but because the explosion is random, all it does is add a bit of background noise to the reflected X-ray pattern without distorting it at all, and because the laser is so much brighter, the results are much better than a conventional X-ray diffraction experiment.  This means that, even though they explosively sacrifice their sample, scientists should be able to discover the structure of proteins more easily in the future.

Why don't we see rainbows under street lights?

Dave - Okay. There are probably two effects with this. One of them is that a streetlight is incredibly less bright than full sunlight. I just did a quick calculation. I think it's a thousand times less bright than full sunlight and something you might have noticed when the light gets very, very dim is that it's very hard to pick out colours because your eyes are much less sensitive to colour when the light is very dim. So even if there was a rainbow there, you wouldn't be able to see it very well. And with some kinds of streetlight, they will actually create a bit of a rainbow. You'd have to be looking away from the streetlight, but it would be so dim, you wouldn't be able to see it.

But there is a second effect which is that a lot of streetlights that have all the colours of the rainbow in them, especially the very yellowy ones, they've actually effectively only got one colour in them, a kind of just pure orange colour. The reason why you can see a rainbow normally is because white lights got all the colours of the rainbow mixed up in it, so the rain could split them up and you can see them in different places. But if the light has just got orange in it, the raindrop can't split it up so all you'll see is orange, so you won't get the colours of the rainbow. Chris - Effectively you get an orange rainbow. Dave - Yes, we just get an 'orangebow' rather than a multicolour one.

Chris - You did an experiment on that for the Crisp Packet Fireworks Book in a Kitchen Science we did a long time ago using your car indicator and a streetlight to show this sort of effect, didn't you?

Dave - That's right. If you look at any kind of brightly coloured thing under yellow streetlights, it just looks kind of gray. Actually, it just looks like orange and black. There's no colour there at all, but then if you take it to normal or sun's normal light, or just look under white torch, it looks all the colours of a rainbow, and even if you look at it in an orange indicator light, quite often, you'll see some colours of the rainbow in there because it's a mixture of green and red, and yellow. So you'll see some colours but under a streetlight, you're going to only see the one.

Chris - There's more than one way to make orange. Dave - There's so many ways in making orange.

How quickly can force propagate?

Chris - Okay, so you've a tube full of balls and you're going to apply force to the ball at one end and you want to see how quickly the force can propagate through the assemblage of balls, yes?

Dominic - Now what's going to happen when you push on the end of the tube is that they're going to compress one of the balls ever so slightly elastically and that is going to then exert a force on the next ball on the tube that's going to compress that force on the next ball on the tube. And that compression can only propagate at the speed of light because no influences can propagate faster than the speed of light. The force you're actually applying here is electromagnetic, so the protons and electrons in your hands will be exerting electromagnetic force against the photons and neutrons in the ball and causing it to compress.

Dave - In fact, it's probably going to be a lot slower than the speed of light because effectively what you're doing, by pushing on something very quickly like that, is sending a sound wave down it and the speed of sound is actually the fastest information can pass through a material elastically. With something like a steel ball, I think that's 5 or 6 kilometres a second, much faster than the speed of sound in air but still, very slow compared to the speed of light.

The moon taken by Appolo 12

05:32 - GRAIL Settles In Around the Moon

A pair of new American spacecraft entered orbit about the Moon over the new year period, with the aim of measuring the Moon's gravitation field in unprecedented detail...

GRAIL Settles In Around the Moon

A pair of new American spacecraft entered orbit about the Moon over the new year period, with the aim of measuring the Moon's gravitation field in unprecedented detail.  Called the Gravity Recovery and Interior Laboratory (GRAIL), the twins will descend gradually towards a low lunar orbit over coming weeks, which by March will see them skimming a mere 30 miles above the lunar landscape.

The moonOnce there, they will begin a 90-day science mission.  Following one another around the Moon at a distance of around 200 km, they will use radar ranging systems to monitor their separation with a precision of 10 micron.  By tracking tiny systematic changes in the distance between them, it will be possible to measure whether some parts of the Moon's surface have stronger gravity than other parts, providing evidence for different types of rock, with different densities, beneath the surface.

Eventually, it should be possible to convert a complete map of the Moon's global gravitational field into a map of the Moon's subsurface geology, from the surface right down to the core.  A similar technique is already being applied to the Earth by the GRACE spacecraft, launched in 2002, which have proven sensitive enough to monitor changes such as the melting of the Earth's ice sheets due to global warming.

On the Moon, these measurements will tell us about the Moon's formation history.  For example, there remains the mystery of why the far side of the Moon is on average 2 km higher in altitude than the near side: a much larger discepancy than can be explained by pure chance.  A recent paper suggested that the Earth once had two moons which collided at low speed, and that the lunar highlands are formed from the remnant material from the collision.  If so, that collision would have left subsurface signatures, and GRAIL will be the spacecraft to look for them.

Why do glasses worn backwards still work?

Dave - This is all to do with how a lens works in the first place. A lens bends light based on the fact that light goes slower in glass than it does in air. So when a light beam hits it at an angle, it slows down on the side it hits first and that tends to spin the light around a bit. A bit like if you're driving a car and you drove one wheel into some sand,, it would spin the car around a bit. It's a bit like that for light. A light ray bends around as it enters the lens, and then when it leaves, the first bit of light to leave the glass will speed up again. causing it to twist around in the opposite direction. So, if light enters a piece of glass where both sides of it are parallel, it will bend as it goes in, but it will do the exact opposite of that bend as it goes out, meaning it will carry on in the same direction it started at. But if you make the two angles on the piece of glass not parallel, so if it's making a curved shape on both sides, then it will get bent differently on the two sides. This means it will end up either pointing inwards, if it's a converging lens or going outwards if it's a diverging lens. If you flip the lens over, even though on the lens from apair of glasses, the two sides don't look identical, it will still be thicker on the outside than on the inside, or thinner on the outside than it is on the inside. And so, the light will also be bent in the same direction it would be otherwise. Although it might not produce quite as good an image, because they put different curvatures on each side to do some very cunning optimisation on the optics.

Is the expanding universe tearing galaxies apart?

Dominic - Well, the universe is expanding because it formed out of the Big Bang which was this massive explosion at the beginning of the universe which imparted momentum and inertia to all the material in the universe and this was initially a smooth distribution of material for the first half million years or so.

After about half a million years, you enter an era that we call the Dark Ages when the first structure started to form in the universe. And what happened at that point was that in some parts of the universe where there was an over density, so where there was a lot of material compressed together, gravity was strong enough to pull that material together and for it to become gravitationally bound into a stucture we call the galaxy.

So, the initial velocity given to that material out of the Big Bang was overcome by gravity and so, the movement of material in that galaxy is entirely determined by the gravitational force in that galaxy. Individual galaxies will be moving apart because they're not gravitationally bound. Their velocity is just still determined by what they were given by the Big Bang. But inside the galaxy itself, it's all gravity now.

Chris - So, even though the universe is getting bigger as a whole, if I were to measure the distance between the Earth and Pluto, even though there's a lot of space in our solar system between the Earth and Pluto, 6 billion kilometres or so, that space isn't actually getting any bigger?

Dominic - Yes, and whether that distance is changing, it will be entirely down to the gravitational forces of all of the planets in the solar system.

What is the oldest known planet in our universe?

Dominic - That is a very tough one. It's very difficult to age planets outside our own solar system because we don't know what they are made of. We can only see their gravitational influence on other bodies. So, it would have to be a planet in our solar system which is about 4.5 to 5 billion years old. So, it would really be all of the planets in our solar system about the same age of about 5 billion years.

Chris - But there will inevitably be older ones out there that we can't see yet?

Dominic - Yes.

Why do colours look different under a sodium streetlight?

Dave - That's to do with the way your brain is attempting to interpret the colour information. Your brain attempts to take into account that different light sources actually look very different. If you have ever seen a photo taken inside with a camera which is an attempt to compensate for this - inside with normal incandescent bulbs, it looks incredibly yellow and your brain immediately tries to compensate for that. What you're actually seeing is the whole thing is actually looking different types of orange, different points of orange because there's only one colour. But your brain is attempting to compensate for the fact that light is very orange and because everything looks orange it assumes that anything is reflective of orange is probably white and anything which isn't is probably dark. And so, you kind of interpret it as white because your brain is compensating. Chris - I got asked something similar by some guys in South Africa about why when you look at ordinance survey maps which have red roads on them for example, if you look at them under a red torch, why the red roads don't look a weird colour and that's the same sort of question, isn't it Dave? Dave - In fact, if you look at a red roads under a red light, they disappear entirely. White reflects red and so does red, so they both look the same.

An American Cockroach photographed in a house in Portland, Texas, United States

16:08 - Cockroach fueled battery

A fuel cell has been developed which can run off the sugars in an insect....

Cockroach fueled battery

There are many potential applications of electronics in biological systems. Glucose sensors, and other health monitoring systems would be extremely useful in humans or other large animals to identify health problems before they occur, or inform and control doses of medication.

One of the biggest problems is powering these devices.  Conventional batteries don't last very long and are often made of toxic materials, while external power supplies are awkward and heavy.  Any living biological system must have an ample source of energy, as a living thing uses energy all the time.  However,  this energy is normally stored chemically as sugars, so accessing this energy source in a way that doesn't damage the creature is challenging.

An American Cockroach photographed in a house in Portland, Texas, United StatesMichelle Rasmussen and colleagues at  Case Western Reserve University have been able to convert the energy in a cockroach into electricity using a fuel cell.  As a source of fuel, they use a sugar commonly found in insects called trehalose.  A genetically engineered enzyme then breaks this down into glucose, which is then oxidised, releasing electrons to osmium ions.  These ions then push electrons around the circuit, as an electric current, to the other electrode, which is covered in an enzyme called bilirubin oxidase.  This second enzyme catalyses a reaction between hydrogen ions and oxygen, producing water.

The components of the fuel cell, both enzymes and the osmium, are bonded to a gel-like polymer which surrounds the electrodes, keeping everything together.

These fuel cells produce a power of about 0.6 microwatts per square centimetre, which, while small, could with a little development be enough to power a small sensor, and occasionally send the data out through a wireless connection.

This technology may well be useful in humans in the long run, but it's main use is as part of a project to create insects capable of carrying sensors into otherwise inaccessible areas.  This should enable the exploration of confined or dangerous spaces,either after accidents or for routine maintenance, and may lead to a generation of insect secret agents!

Acoustic and Electric Violins

19:10 - Stradivarius reputation bows under pressure

The reputation of the famous Stradivarius and Guaneri names on violins has been dented by a new study showing that, in a blind test, musical professionals cannot tell the renowed...

Stradivarius reputation bows under pressure

The reputation of the famous Stradivarius and Guaneri names on violins has been dented by a new study showing that, in a blind test, musical professionals cannot tell the renowed instruments from modern counterparts.

In a trial published in PNAS and conducted, the authors report somewhat dubiously, in a hotel room at an international violin event in Indianapolis, 3 old violins dating from between 1700 and 1740 - two were Stradivarius and one was a Guaneri del Gesu model - were compared with three modern instruments built within the last few years.

Acoustic and Electric ViolinsA panel of 21 professional musicians were asked to play each of the instruments and to rank the tone, playability, projection and response of the instruments, and also to pick out the ones they would most and least like to take home.

To avoid bias the participants were given welding goggles to wear to prevent them from picking up on any visual clues as to the age of the instruments they were playing, and the violins were further disguised with a blob of perfume applied to the chinrest to mask any olfactory giveaways.

Despite their combined $10 million price tag, which was over 100 times greater than the modern instruments, the violins rated least playable were those by the old masters.  A Stradivarius was also the model most consistently listed as the instrument that the players would least like to take home with them.  The assessors found no differences in the overall sonic performances between the old and new, however.

This is the first time that such a blind trial has been carried out and, albeit based on a small study sample, seems to suggest that the reputation of the greater masters' violins relates more to the price tag than the sweet music they make.

Indeed, as lead author Claudia Fritz from CNRS in Paris points out, "in a recent wine tasting experiment, it was found that increasing the stated price of a wine increased the level of 'flavour pleasantness' reported by subjects. Could," Fritz and her colleagues speculate, "a violinist's preference for a Stradivari violin be in part attributable to an awareness of its multimillion-dollar price tag and historical appearance, both of which may be signaled by its distinctive appearance?"

What causes ringing in the ears?

Chris - The most common reason we get ringing in our ears is because we experience a sound that's too loud. You have about 16,000 of these tiny things called hair cells in your inner ear. The inner ear contains a structure called the cochlea that quite literally turns sound wave vibrations into brainwaves - nerve energy. It does this because these little tiny hairs are set vibrating and when they vibrate, they pull open a little channel, or a pore, in the surface of the cell to which they are atached. This pore lets potassium into the cell and it changes the nerve activity in the cell. This is then signalled via the nervous system into your brain and interpreted as hearing noises.

If you're exposed to a really devastatingly loud noise, or a noise that's too loud for too long, then the tips of these hairs can break off, jamming the channel open for a while. This means more potassium will go into the cell, and so the cell continuously stays active, so you keep hearing a sound even though there's no sound there. Luckily those nerve tips or the hair tips can re-grow. But if you're exposed to really, really, really loud sounds, or a very loud sound for a very long period of time, you can actually rip away all of these so-called stereocilia, the hair cells, and the cell can die. I did read one quote that said, when you stand on the underground and a big train goes past very loudly, a handful of those cells dies every time. So over time, as you age, you lose these things, unfortunately and you do end up deaf once you get to your old age. Dave - So what causes a ringing which carries on going on for a long time? If the cell dies, would that still cause this noise? Chris - What probably happens once you get a chronic problem is that you are removing from the brain the input from the cochlea, corresponding to the particular frequency that those cells would have signalled. The brain thinks that it's gone deaf so it turns up the "amplifier". The brain listens a bit harder for the sounds it's expecting and they're not coming, so it turns it up a bit more. It's a bit like what happens when you're tuned to a radio station and it's not a very good signal - when you turn the radio up, you hear some hiss in the background. If you keep turning it up, the hiss gets louder, and louder, and louder, and that's effectively what the brain is doing, or at least that's one model of what we think the chronic problem, known as tinnitus, actually is.

The first stars in the Universe turn on at about 400 million years after the Big Bang. WMAP data reveals the era.

Can a star form outside a galaxy?

Dominic Ford provided this answer...

Dominic - Stars form from clouds of gas that we call molecular clouds and they form when the gravitational self-attraction of that cloud is stronger than the gas pressure which is pushing that cloud outwards. You can get a sort of chronic failure of gravity where the whole cloud collapses down to tiny points and begins fusion and becomes a star. It's actually quite difficult to trigger that initial condition where the cloud is dense enough to collapse down. You generally need something to give it some kind of compression to get the process started. One of the most likely candidates would be another star nearby going supernova, or if you're in a spiral galaxy like the Milky Way and you travel through one of the spiral arms, that's a density sound wave and if you travel through that sound wave, you're compressed and that causes a star to form.

In intergalactic space there aren't really any processes that could cause molecular clouds to collapse down like that and so I'm not aware of any theories that would allow stars to form in intergalactic space. But it's certainly the case that stars can be ripped out of galaxies and then become free-floating in intergalactic space. If, for example, two galaxies come very close to one another then the outskirts of those two galaxies can be thrown off at high velocity into intergalactic space. They form what we call strings with long strings of stars stretching out of galaxies into intergalactic space.

Why do we see green flashes during sunset?

The last bit of sun you see as it's going under the horizon is actually when the sun is already under the horizon, and what you're seeing is light being bent by the atmosphere, a bit like light is in prism and it's actually bent down towards you. Now, red light is bent less than green light which is bent less than blue light. And so, as the sun goes down, the very, very last light you should be able to see would be blue and then just a bit before that you'd see green, and the bit before that you see yellow and red. But normally, the atmosphere is too dirty if you're to ever see the blue because blue gets scattered out because the sky is blue so the blue is just isn't there and also normally, the atmosphere is too dirty to see the green. But if you happen to be on an incredibly, incredibly clean atmosphere, it normally happens out at sea because there's less dust in the atmosphere out at sea, because there's less dust there. And if it's been very, very calm, you can just sometimes see that green light being refracted around by the atmosphere and you get this thing called a green flash and it's incredibly rare. I've known somebody who's seen it a couple of times.

Water droplets

Is any new water being formed on our planet?

Chris - The answer is yes, there is!

The process of, if we say, respiration - that's the best example, if you look at the metabolic processes that are going on in every single living thing on Earth - what we're largely doing is burning a fuel; let's take sugar, glucose, C6H12O6, and we react it with oxygen (O2), the products of that reaction are CO2 - carbon dioxide - and, you've guessed it, H2O - water.

What you've effectively done is you've rearranged some of the atoms in the sugar molecule, mixed them with some oxygen and you've made some water de novo.

So there is water coming out of that reaction, and, at the same time, you've got plants, which are gathering energy coming in from the Sun and they're using the process of photosynthesis to drive the reverse reaction; so they're taking carbon dioxide out of the air, they are mixing it with water which they've got from their roots, and if you take the CO2 and the H2O, and the energy from sunlight to drive the equation the other way, you then get - you've guessed it, C6H12O6, you're back to glucose again!

So, although there are no new atoms being made on Earth [except by radioactive decay], there are nonetheless, new arrangements of those atoms - new molecules - so you are making water which didn't exist before by rearranging the atoms...

What's the difference between MRI and fMRI?

Chris - Well they both use the same principle - magnetic resonance imaging. Dave - Magnetic Resonance Imaging actually should be called nuclear magnetic resonance imaging but they took off the nuclear because it scared people even though it's not at all dangerous in any way, shape or form. What it's doing is looking at the nucleus of atoms. In fact, in MRI, it's looking at the nucleus, nuclei of hydrogen atoms. If you put them in a very strong magnetic field, it affects the way they interact with radio waves and then by an incredibly complicated bit of maths and some big computers, you can basically have different bits of your body in different strengths of magnetic fields which means that they interact with different radio waves and by keeping changes in the magnetic fields in lots of different directions and doing lots of hard maths, you can build up a picture of where all the hydrogen atoms are in your body and also, something about how they are chemically inside the molecules which they're sitting in. Chris - Yeah, that's basically what they're doing and if you want to do functional magnetic resonance imaging, what they are doing is looking at the level of oxygen which is in the blood and so, you infer how active, say you're looking at the brain and you want to know, is this bit of brain active when I do a certain job, you look at how oxygenated the blood is that's going through that area because an area of the brain which is more active uses more energy and it gets more energy by burning more glucose with more oxygen. Therefore, it augments its blood supply and you can use that as a measure. Dave - And I think there's a second thing which they can do which is, they can actually look at the flow of blood because they can kind of magnetise your whole body very quickly with radio waves and then they can look at how the magnetisation moves in your body and they can look at where that's moved and anywhere it's moved, there's probably will be blood flowing and so they can work out blood flow just by what's moved inside the body.

Sumatran orangutan at the Orang rehabilitation centre, Buket Lawang, Sumatra.

33:21 - Parkour and Primate Movement - Planet Earth Online

Free-runing, or parkour, is helping scientists understand how orang-utans move across a forest canopy...

Parkour and Primate Movement - Planet Earth Online
with Suzanna Thorpe, University of Birmingham

Chris -   If you think of the opening scenes in the movie Casino Royale, James Bond chases a villain who swings and slides, and jumps along a crane and across various rooftops.  This is actually a sport known as free running or parkour, and it's now helping scientists at the University Birmingham to understand how one of man's closest relatives, the orang-utan, travels through the canopy of a rainforest.  Planet Earth Podcast presenter Sue Nelson met Dr. Suzanna Thorpe from the University's School of Biosciences to find out more...

Suzanna -   What we're doing here is using the parkour athletes as an analogy for a large bodied ape moving around a complex environment.  We're getting them to move around an assault course that we've made, that they've never seen before, and we're going to record their energetic expenditure while they're doing it.  The reason we're doing the study is that orang-utans and the other great apes move around the canopy of tropical forests and the branches there are very flexible underneath their weight because the animal is so large.  Here we have lots of supports that we can make behave like branches in the forest, we can set up the assault course so that it's very complicated, as moving around a forest canopy would be, and we can confound how the supports behave.  So, we can have supports that appear to be stiff that we make compliant and supports that are quite compliant that we actually make to behave in a stiff way.  That mimics the challenge that a large bodied ape would face moving around the canopy, when they have to look ahead of them and judge how the supports available to them are going to behave without being able to test them.

Sumatran orangutanBrendan -   The way I would do it to get the best swing is I would jump up and backwards and reach one arm up, swing to the other side and as I get to the end point, swing that one arm back down...

Sue -   The athlete that's helping the scientists here is Brendan Riley from EMP Parkour.  What are the basic moves?

Brendan -   A simple vault would be the cat pass, which is like a through vault in gymnastics.  You have the tic-tac, that's kicking off a wall to propel yourself higher or further.  You have a speed vault, that's a really efficient vault, just one handed, and then there's a bunch of other ones which are less efficient but just as much fun.  Then the main thing we do is a precision, that's just jumping from one thing to another, or if you grab hold with your hands and that's called an arm jump.

Sue -   How do you feel about helping scientists here examine how primates move?  I assume you're not insulted by this?

Brendan -   Not at all.  I love monkeys, I love apes, I wish I was a gibbon.  I think I probably was in a previous life.  It sounds weird but we look up to primates.  We look at their movements and it's very inspirational.  I know some guys who have actually been to different parts of the world just to see how the monkeys move and have been training with them.  I think it's brilliant.

Sue -   In order to work out what the energy costs are for the parkour athletes as they complete the circuit, you need to take some measurements and that's where Dr. Lewis Halsey comes in.  He's a senior lecturer in environmental physiology at the University of Roehampton in London.  So, Lewis, what are you going to measure and how are you going to do it?

Lewis -   The primary thing we're interested in is the energy costs for our parkour athletes as they traverse the circuit, as they use various bits of apparatus.  We're going to measure that by measuring their oxygen consumption.  So, we're going to put onto their backs, essentially, a portable oxygen analyser.  It'll have a mask and the oxygen consumption of the person and the carbon dioxide output at the same time is measured, and that's all relayed to a computer.  So in real time, we can see the various costs of the various apparatus they're using.  There's an added twist to this, which is at some points, they may partly use anaerobic metabolic pathways and the analyser can't pick that up because it's measuring oxygen consumption which is involved with aerobic pathways.

Sue -   Suzanna, it's an amazing experiment and I can't wait to find out what the results are going to be, but there's quite an important reason isn't there for actually doing this project?

Suzanna -   It's important for lots of different reasons.  One, from the perspective of understanding human evolution and the challenge that the common ancestor of all of the great apes would face and also, our ancestors would face when they were partly arboreal and partly moving bipedally on the ground.  Secondly, from a conservation or an ecological perspective, if we understand a lot more about the challenges that orang-utans face in the canopy and the solutions that they find to solve them and the energetic cost of doing so, then we can better construct conservation strategies for them.  They are predicted to be extinct within ten years in the wild if we don't do something about it.  So, finding the most effective way to structure a habitat or picking the most effective habitat for them for rehabilitance, is a good way to help contribute towards their conservation.

Would a siphon work in free fall?

Dominic - Yes, it is. When you're in free fall, you're essentially in zero gravity because all parts of your spacecraft are falling at the same speed towards the Earth and normally, you feel gravity because "I'm feeling an attraction towards the Earth and I'm being stopped from falling towards the Earth by the chair underneath me and so the chair has to push me up to stop me from falling towards the Earth".Dave - The only thing which might be slightly different and they have to be careful design of their experiment, is that they've only got free fall for 2 seconds. If they'd already started the siphon before they dropped into free fall, the water has got lots of momentum and that momentum will actually keep it flowing for quite a long time. So they'll have to open the valve or something after it's dropped. Otherwise, they're not doing a fair test.

How does a cuckoo know it’s a cuckoo?

Chris - No one knows for absolute certain but one theory is that the cuckoo's parents may pay a visit to the nest that they cuckolded and visit their chick as it's reared so that it imprints on them because one of the things about birds is that they imprint - in other words, they recognise objects that are nurturing them as their parents - and you can actually make them imprint on inanimate objects. If you have a bird and you put it in contact with the door that opens and closes, it can end up thinking that the door is its mother and it will follow a door around bizarrely and so, one theory is that the cuckoo's parents do occasionally pay a visit so the cuckoo recognises that it is genuinely a cuckoo. That or there's some other genetically programmed innate behaviour that's in there.

Histopatholgical image of hepatocellular carcinoma in a patient with liver cirrhosis by chronic hepatitis C infection. Hematoxylin and eosin stain.

40:30 - Chimp Viruses Vaccinate Against Hepatitis C

Over 170 million people are infected with Hepatitis C worldwide and at the moment there is no effective vaccine. But now scientists may have found a way to protect people – by adding parts...

Chimp Viruses Vaccinate Against Hepatitis C
with Professor Paul Klenerman, University of Oxford

Chris - Two papers were published this week in the journal Science Translational Medicine discussing a promising new vaccine for hepatitis C.  Now this is a virus that spreads from blood to blood contact and in over 80% of people who contract it, it sets up a persistent lifelong infection that progressively damages the liver and leads to cirrhosis and in some people, liver cancer.  Now over 170 million people are infected with this worldwide and at the moment, there is no effective vaccine.

But now, scientists may have found a way to protect people by adding parts of the hepatitis C virus to a harmless cold virus called an adenovirus that actually normally infects chimpanzees.  This modified virus triggers the immune system to mount a strong response against hepatitis C and that can prevent a person from developing a chronic infection if they're exposed to the virus for real at a later date.  Ben Valsler spoke to Oxford University's Professor Paul Klennerman about the work.

Paul -   The specialty of hep-C is that it sets up chronic infection in humans.  So, even if you've got a relatively intact immune system, you don't seem to normally be able to mount an immune response that gets rid of the virus.  If people do become chronically infected, some people handle that pretty well and in fact, they have very little inflammation in the liver which is the major consequence.  But some people have much more inflammation in the liver and as a consequence, much more scarring on the liver tissue and so over time, they can develop end-stage liver disease, so cirrhosis and also liver cancer.  It's turned out to be one of the main reasons people need transplantation in this country and in the western world.  Having said that, the other interesting feature of hep-C is that a fraction of people end up clearing the virus on their own.  That was actually very attractive from the point of view of a vaccine since we already know there's some form of immunity which is efficient.

Ben -   What sorts of target have we been looking at for actually making a Electron microscope of Hepatitis C Virusvaccine?

Paul -   Broadly, the way you might think about making a vaccine is to make either an antibody response or a cellular immune response, so that's mounting a white cell response that targets the infected cells directly.  The problem with hep-C in terms of antibody response is that the envelope of the virus is quite variable.  So the alternative approach is to try and target the virus as it's replicating within cells and that really relies on mounting a T-lymphocyte response. 

The T-cells will actually look at proteins which are generated during the process of viral infection, so that can be proteins which are part of the machinery of viral replication.  If the T-cell really can recognise those cells, it will secrete chemicals, cytokines, which are directly anti-viral and will limit the viral infection and they can also kill the infected cells, so actually destroy the virus within it.

Ben -   What are you now doing to target that and where are your "weapons" coming from?

Paul -   The trick seems to be to stitch in the bit that you want - in our case, as I said, the internal proteins of hep-C - into something that's really going to get the immune responses fully activated.  In our case, we've used an adenovirus.  This combination of using an adenovirus with the hep-C internal proteins seems to produce very strong immune responses of the type that we see in people who naturally clear the infections.

Ben -   Aren't we already immune primed against adenoviruses?

Paul -   Yeah, that's a very good point.  So I think one of the reasons adenoviruses are good is that the body is very used to seeing them, but exactly for the same reason, we already have immunity.  So, we've gone for an approach using vectors which people won't have seen before or at least will have rarely have seen.  So one of these is a human adenovirus, but just a rarer strain, and the other is a completely novel vector which comes from a virus found in a chimpanzee.

Ben -   What sorts of results are you seeing?  Are you actually getting the immune response that you expect?

Paul -   There were two interesting bits of the trial.  We exceeded our expectations with the priming.  So if you take someone who's not got any immune response against hep-C, give them the vaccine, they generated very big responses.  The levels were higher than we expected but we were pleased to see that also, they targeted a lot of different parts of the virus, because that's really important if you're going to overcome the variation that's already embedded within the viral genome.  They did the kinds of things that we'd like the T-cells to do; so they proliferated well and they made the cytokines that I mentioned and they look like they would kill an infected cell.  

The second stage is where we're trying to boost with the alternative adenovirus - we had two viruses and we gave a group of patients each one but in different orders.  This boosting effect was a bit less than we'd expected and we think that's probably because of what we were just discussing, that once you've seen one adenovirus, you start to make immune responses against it.  But the net result, which I think is the important one, is that after six months or a year, so well after the vaccination, we still had very big populations of cells which still seem to have the qualities that we'd really like in a protective response.

Ben -   Is it safe to be using viruses that have adapted for other species?

Paul -   We went through a number of safety committees to try and make sure this was as safe as possible.  I think the key thing is that the viruses are made so they're replication incompetent.  A large chunk of genetic material is removed and it's really not possible for the thing to repair itself to become an infectious virus.  You can't really expect to make progress in this field if there's any even small hint of a risk from these things because you would be giving them to completely healthy people in very large numbers.  So you have to eliminate as many risks as you can possibly imagine.

Ben -   So, you've done everything you can to make it safe.  It seems to be very effective.  What's the next stage?

Paul -   It's nice to see these responses but they're all in the test tube, so any vaccinologist would really want to know whether they were protective.  What we'd have to do, and what we're planning to do with collaborators in this States, is to look at people who are at high risk of infection.  In Baltimore, there's a very well established group of intravenous drug users where, because they use needles, they're putting themselves at risk of hep-C.  So, they've designed a trial where they imagine that the rates of infection are sufficiently high that we could really see an impact from this vaccine.  So that's planned to go ahead now that we've developed the vaccines to this stage.

An Atlantic Hydrothermal Vent

46:56 - Spiderworms, Exploring Vents, Clues to deafness and Bulking up!

Silkworms producing spider silk, new species discovered at hydrothermal vents in Antarctica, a gene providing new insight to deafness and the science behind bulking up this new year...

Spiderworms, Exploring Vents, Clues to deafness and Bulking up!
with Randy Lewis, Utah State University; Alex Rogers, University of Oxford; David Ornitz, University of Washington; Athanassia Soritopoulos, INSERM

Spidersilk from Silkworms

Silkworms have been genetically engineered to spin spider silk proteins, producing a tougher, more elastic silk material.

Farming of spiders for their silk production is challenging due to small production levels and cannibalism within populations.  Publishing in the journal


PNAS, Randy Lewis and colleagues from the Utah State University overcame this problem by creating transgenic silk worms containing spider genes for silk elasticity and tensile strength resulting in a composite of worm and spider silk produced in large quantities.

Randy -   Certainly, one area that we're very interested in is artificial ligaments and artificial tendons for ligament and tendon repair.  We've got collaborators who are interested in using it for helping them build a very strong bone matrix, or very fine sutures.  Beyond the biomedical, there's interest in things like parachutes.  We can also match different applications.  So for a tendon, you want something that's very strong and not very elastic.  For a ligament, you want something that's strong and very elastic.  So, we'll be custom designing our genes and the silkworms to make a specific silk that has a very specific application.


New Species at Antarctic Vents

Unique communities of marine species have been found on the Antarctic sea floor, living in hydrothermal vents off the coast of the East Scotia ridge in the Southern Ocean.

Using remotely operated vehicles, Alex Rogers' team from the University of Oxford discovered new species of yeti crab, stalked barnacles and seven-armed starfish, unseen anywhere else in the world, whilst animals such as tube worms and vent crabs, commonly associated with hydrothermal vents, were nowhere to be seen.

The team suggest the southern ocean may act as a barrier, resulting in a more diverse vent ecosystem globally than previously thought.

Alex -   The southern ocean may act as a gateway for the dispersal of some of these animals from one ocean to another, but that very harsh environmental condition of the southern ocean probably means it acts as a barrier for the dispersal of other groups.  The East Scotia region is somewhere between 10 and 20 million years old, so it would seem that these animals may have become isolated on the ridge shortly after it was formed.  The distribution of vent animals and the evolution of hydrothermal vent faunas around the globe is much more complicated than we previously suspected.


New gene target identified for deafness

A new gene identified in mouse models could provide insight into the causes of human deafness.

David Ornitz and colleagues from the Washington University school of medicine in St Louis found that the gene,


named FGF20, which codes for a family of proteins called fibroblast growth factors, was crucial for the formation of outer hair cells - sensory cells needed to amplify sound in the inner ear.

The gene has previously been linked with inherited deafness in humans and could lead to treatments for hearing loss.

David -   FGF20 is a critical signal for the formation of outer hair cells and might be a deafness related gene in humans and it is our hope that FGF20 may be useful to either protect or help to regenerate sensory hair cells that have been damaged by noise, by drugs, or through the ageing process.


The Science behind Bulking Up

And finally, as many of us start the new year with a resolution to workout, the key factors needed for our muscles to grow and bulk up during a workout have been discovered by scientists at the Inserm institute in France.

Working with mice,  Athanassia Sotirorpoulos identified the need for serum response factor, or SRF, in working muscle fibres to signal the proliferation of satellite stem cells found within muscle which then grow and fuse to existing muscle fibres resulting in growth.

Muscle was shown not to grow in mice lacking the SRF gene.

Athanassia -   The implication is that, for example, during ageing, there is a muscle atrophy that is called Sarcopenia or when you are immobilised at bed, you get very important muscle atrophy.  So, if we can identify all the genes that are really involved in controlling muscle growth then we can use those genes to have less wasting during ageing or during your bed resting.

The work was published in the current edition of the journal Cell Metabolism.


Could a lead barrier protect us from the solar wind?

Yes. In fact, that is a technology which has been tested on the International Space Station to keep the astronauts safe if the solar wind should flare up. In fact, they don't tend to use lead because lead is so heavy and obviously, weight is very important in the International Space Station. But a thin layer of metal or plastic is enough to deflect the particles.

When looking in a mirror why does left become right?

Dominic - That's quite a good brain teaser. In fact, when you look at yourself in a mirror, nothing is inverted at all. When you look at where the left side of your face is in the mirror, it's on the left hand side exactly where you might expect it to be. But if I turn around and look at Dave then I've had to swing myself around and invert my definition of left and right by swinging myself around and in doing that, my definition of left and right is the opposite to Dave's, so I see his right side on my left side. Dave - So does that mean that if you turned around, instead of turning around left or right, you you just did a forward roll and turn yourself up - so you turned around to look at me by inverting yourself - Would up and down be swapped instead of of left and right being swapped? Dominic - That's absolutely right. I don't think I'll try from the studio, but if I were to stand on my head to look at you, I'd see up and down inverted rather than left and right. Chris - Is this important in your field of space science when you're looking in telescopes and things like that? Dominic - Yes. Certainly, with telescopes, different sides, left and right, top and bottom will be inverted in different kinds of optical system and you do have to worry about that, yes.


57:32 - Do sunglasses cause sunburn?

Do sunglasses fool your body into not releasing enough melanin to protect you from the Sun's harmful rays?

Do sunglasses cause sunburn?

We posed this question to Cambridge Laboratory of Molecular Biology scientist Mick Hastings, who shed some light on the subject...

Mick - The bottom line is, no, but it is an intriguing question. Melanin is produced in response to light actually in the skin itself. It doesn't come from any glands, but there is a gland called the pineal gland - not the pituitary gland, the pineal gland - which produces something called melatonin.

The interesting biology here is that melatonin can affect pigmentation of the skin in amphibians. In fact, that's how it was discovered. But melatonin has no effect on the skin of humans.

It's actually melanin that makes us go darker in response to the sun. There's still another neat piece of biology underlying this, and that is to say that, in recent years, what's been discovered is a completely novel set of light responsive cells in the retina called intrinsically photoreceptive retinal ganglion cells. They're nothing to do with enabling us to see the world around us, but they are there for us to sense changes in light intensity and quality. These cells have a very important affect on our mood, on our biological clocks and our circadian rhythms. 

So, at some level, if one were to wear sunglasses, it would affect not just how we see the world in terms of objects, movement and colour; it would also affect our response in terms of our mood, which would include heart rate, pupil contraction, things like this.

So there are some subliminal effects of light on the body which will be influenced by wearing sunglasses but to cut to the chase, this will not affect whether or not we're more or less sensitive to sunburn and sun tanning!


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