Better to blow up an Earth-bound Asteroid?

15 July 2012

Should we blow up objects on a collision course with Earth? Or will they do less damage left intact? More importantly, is there a gene for hating marmite? And what makes copper such a good conductor? How would a caveman cope in modern society? What's the secret to how balls spin in sport, and why does wrapping vaccines and antibiotics in silk make them last longer. Plus, why physics says Batman's cape won't work...

In this episode

01:29 - Can beer prevent dehydration?

Can beer prevent dehydration?

Diana - Well, the answer is, yes, it probably is okay to drink the beer as long as its alcohol content is less than 10%. So, if you're not going for the things like Special Brew and the really hardcore beers, then you're probably actually going to hydrate yourself rather than dehydrate yourself overall. And another little tip is that if you do perhaps only end up with wine or something that does have more than 10% of alcohol in it, then maybe if the temperature is high enough, you might be able to undo the top, leave the alcohol to evaporate a little bit, and maybe reduce the overall alcohol content. You might have something - well, it won't be very nice to drink. It might save you, you never know.

Chris - So there's a threshold concentration at which we think there's a beneficial effect of about 10%. Beyond that, people are going to dehydrate net, but they'll have some fun under that then probably, you'd be okay to drink it and it will do you a benefit.

Diana - Yeah, that seems to be the case. And also, a little factoid, in the medieval period when freshwater was just so horrible to drink, everybody used to drink small beer which was very low alcohol beer. Obviously, they didn't all become desiccated and dried out like prunes, so it must've worked.

Chris - I remember, when reading archaeological texts and things, you see that the people building Hadrian's Wall, for example, were given a ration of beer every day and it was largely all that was being served. I remember thinking when I was little, "Gosh! Weren't these people permanently drunk?" But it's because the alcohol content was low.

Diana - Yes, that's right.

03:41 - Should we blow up an Earth-bound object?

Should we blow up an Earth-bound object?

Dominic - That's a serious question that NASA have been doing research into and there are two approaches that you can take to avoid the comet from impacting the Earth. You can either give it a very small nudge and try and change its orbit so it doesn't actually end up on a collision course with the Earth, but it skims past us. Or you can try and blow the comet into smithereens so that none of those small pieces can cause very much damage. The problem is, you need a very large explosion to break one of these comets apart and if you for example, fire a nuclear missile at a comet, it's then going to become radioactive and you may just end up with a lot of large fragments, each of which could wipe out a city of people and might be radioactive to boot. It really actually all depends how far away the comet is and how much warning we have, and how much planning we can put into what the response would be.

"Hi, guys. I think it's not a good idea to blast it to pieces because the bits would break up and then they pound the earth with lots of craters and rubbish."

Marc Hampson via Facebook

"It depends on how big the resulting rubble is. If the individual pieces were small enough then they would all burn up in the atmosphere. I prefer the idea of painting one part of it and using the extra absorption of light to steer it away from a collision course. If we could convince some clever engineers to paint a logo on it, we can get some multinational company to sponsorship for the whole action."

Andrew Reitemeyer Dominic - You would need quite a lot of warning because that would be quite a slow way of deflecting the comet. One of the principal problemsis that we don't have a very good idea of what comets are made of and how structurally sound they are. So, in terms of firing something out and try and break them apart, we don't really know how they would fragment.

Chris - The point about sunlight though, just in case anyone doesn't believe that that's feasible, there is something called the YORP effect which is Yarkovsky-O'Keefe-Radzievskii-Paddack effect which is photon pressure. So when photons, like packets, hit a surface, they impart a nudge or some momentum to it and it is capable of moving big objects given enough time. There was some modelling done for the asteroid belt and a lot of the impactors that we think did away with the dinosaurs, you can retrace their history; they probably came out of the asteroid belt somewhere near Mars; and we think that some object was dislodged by the fact that you have this nudge from the pressure of light.

Dominic - Yeah, and it's a very small effect, but the first detection of that was actually made only about 2 years ago. There is an asteroid, but it has been detected that the sun is putting pressure on it and pushing it out.

Chris - Hugh, you passed me a note here about Barnes Wallis. Tell me more. Is this in relation to the asteroid question?

Hugh - Well, I'm not a great expert on asteroids, but one thing that Barnes Wallis found out during World War II was that dropping 40 250-pound bombs is not going to blow up the dams of Germany, but dropping one bomb which is 10,000 pounds would. So, it strikes me then by similar argument that it's probably better to have 40 small asteroids than one big one.

07:36 - Has the human brain developed at the same rate as the human body?

Has the human brain developed at the same rate as the human body?

Diana - I think, yes, of course. Someone who lived 10,000 years ago would be very capable of understanding all of the problems and issues that we have to deal with today. In fact, around 10,000 years ago, it was when humans were doing really incredible things like developing agriculture which would have taken some intelligence, and doing what essentially is modification of different grains and vegetables, and things which takes some foresight and some planning. And in fact, the anatomically modern human, as it's known, first appeared 200,000 years ago and there's no evidence to suggest that people then had different brains to the ones that we have now. Although there are some arguments about maybe something happening around 60,000 years ago, but we don't really know for sure, but it looks like certainly 10,000 years ago, people were just as intelligent as they are now. [But the type of intelligence has probably changed over the last few Millenia because people are exposed to very different problems in their day to day lives.]

Chris - How do we know that the brains of people 200,000 years ago were similar because brain tissue doesn't fossilise, does it? So how would we know that?

Diana - To be fair, it is a little bit of guesswork. There is genetic evidence to show that anatomically modern humans have - well, we have evolved a little bit. There are a few mutations that have turned up over the last few hundred thousand years, but if you take a fossil of a human and open up the brain case, look inside at the shape and the volume, and the way that all of the little veins and vessels are marked out on the inside of the brain case, it actually doesn't look very different at all from what we find now.

Chris - So, you're referring to the idea of the sort of endocast idea where the shape of the skull can form a fossil on the inside where the brain would've been, leaving an imprint on what the brain must've been like because the brain leaves its own imprint on the inside of the skull.

Diana - Yes, that's right. Yeah, your brain does imprint in the inside of your skull as you grow up, strangely enough!

10:00 - What are Prions?

What are Prions?

Chris - Prions are the names given to these proteins found in the nervous system and also elsewhere in the body, which are responsible for diseases like BSE: Bovine Spongiform Encelopathy, mad cow disease. In humans, the equivalent is CJD: Creutzfeldt-Jakob disease.

These proteins are normal for the brain. We normally make them, but we make them in a shape or form called PrPc. This is a globular protein that looks a bit like a ball of wool and it dissolves really easily. No one actually knows exactly what it does in the nervous system, but it's a normal part of everyone's nervous system and other parts of the body as well including the immune system. But for some reason and probably because of the shape of the protein, this ball of wool can sometimes get tangled into a rigid fibrous shape called a beta-pleated sheet. And when it forms this beta-pleated sheet shape, then what can actually happen is it can make other "ball of wool" shape prions also convert into these rigid beta-pleated sheets, and from where you had 1, you now have 2 and 2 can convert 2 more, making 4, and 4 can go out and convert making 8 and so on. And the whole thing grows exponentially.

They build up in the brain, and they appear to be directly toxic to nerve cells which is why you end up with this spongiform change in the brain because you lose nerve cells and replace them with vacualation or gaps or holes in the brain. It makes your brain a bit like Swiss cheese and they appear to be able to transmit. So if you eat material which is contaminated with prions from a closely related animal like a cow, they can cross the species barrier, get into our body, go the nervous system, and then they make the person develop BSE or human BSE in this instance. So that's the prion story. It won a Nobel Prize for Stan Prusiner who first came up with the idea.

11:58 - Magnetic Field Receptor Cells Identified in the Nose of a Trout

Researchers this week have found the very cells that make up the internal compass of migratory animals. These cells are able to detect the position of the animal in relation to the Earth’s...

Magnetic Field Receptor Cells Identified in the Nose of a Trout

Researchers this week have found the very cells that make up the internal compass of migratory animals. These cells are able to detect the position of the animal in relation to the Earth's magnetic field, and they do this because the cells themselves contain a magnetic component. 

MagnetocellLed by Stephen Eder of Ludwig-Maximillians University in Munich, the international team took cells from the olfactory organ of a trout - that's the trout's snout - and placed them in a strong, rotating magnetic field under a microscope. Because of the way in which these cells had been prepared, they were able to move freely as the magnetic field in which they were placed rotated. When the magnetic field was applied, only the magnetic sensory cells would follow the movement of that field.

In previous years researchers have found it rather challenging to identify these cells because their exact location is quite often a subject for debate and because, in order to work effectively, these cells have to be few and far-between. When the team did identify the magnetic cells, they discovered that for every 10,000 epithelial trout snout cells, there were only about 4 of these magnetic sensory cells. And this rarity was necessary because the magneto-sensing cells had to contain a magnetic element, which itself would produce a magnetic field and could disrupt other sensory cells nearby. 

The researchers believe that the cells contain the magnetic substance magnetite, which is about as magnetic as you can get in naturally occurring minerals. The next question is, given that these cells cannot rotate freely when trapped in the tissue of a living animal, how do they signal changes in the magnetic field? In the trout cells, these crystals of magnetite are locked inside the cell membrane, and the researchers hypothesise that they cause the membrane to stretch when pulled in a particular direction by the earth's magnetic field. So, at a cellular level, it may be that this membrane stretching induces a signal to the animal, telling it which way is north. 

And that work is published in this week's edition of PNAS.

14:28 - Is the Higgs Field constant?

Is the Higgs Field constant?

Dominic - So if we step back for a moment to what the Higgs actually is. I find this rather interesting because the problem which has been facing particle physicists for the last 20 or 30 years is looking at the zoo of these strange particles we have in the universe - the quarks that make up protons and neutrons; the electrons, the photons, the neutrinos, etc. And wondering whether these are just a random set of particles we have in the universe or whether there's some pattern to their properties. And one problem has been explaining why some of these particles, like quarks, have mass and others, like photons and neutrinos, don't have mass.

What Peter Higgs did in the 1960s was to show that although these particles don't form any pattern, just with the ones that we have seen, if we have one more particle - which is the Higgs Boson - then you got a very nice pattern which could explain why some of these particles have mass and others don't. It's all to do with whether they interact with the Higgs Boson which creates this Higgs field and mass is given to a particle by its interaction with that Higgs field. Now in terms of the properties of that Higgs field, I think we're going to learn more about that from the LHC in the next few years as they study this particle they seem now to have discovered. I think the general thinking is that the Higgs field is constant throughout the whole universe, it would be created by Higgs Bosons popping out of the vacuum. But I'm sure we will learn more about it in the next few years.

16:16 - Did temperature altering sex ratios make the dinosaurs die out?

Did temperature altering sex ratios make the dinosaurs die out?

Diana - Well yes, temperature certainly has been linked to the demise of the dinosaurs, but normally, people associate it with the destruction of food availability or that plants could no longer grow in colder conditions. So what you're talking about is something called Temperature-dependent Sex Determination which happens in crocodiles and turtles as well. Normally, what happens is when eggs are incubated at lower temperatures, you tend to get more males. When they're incubated at higher temperatures, you get more females, although there are some variations on this. Now we know that TSD - temperature dependent sex determination - happened about 300 million years ago so that is when the dinosaurs were around so it's possible that dinosaurs did this. But birds, which are descendants of dinosaurs, determine their sex genetically. It has nothing to do with temperature. So at the moment, we can't really argue that dinosaurs did have this way of determining sex. And the other counter argument is that crocodiles and turtles have survived the asteroid collision - obviously, the temperature didn't affect their breeding and also, there's evidence that dinosaurs actually purposefully laid their eggs in geothermally warm places so they could actually control the temperature of their nests.

Chris - A natural incubator.

Diana - Exactly, that kind of thing. So, the TSD hypothesis is an idea that could potentially be true, but I think at the moment, it seems quite unlikely.

18:29 - The Spin of a Bouncing Ball

The Spin of a Bouncing Ball

Diana: I've got Hugh opposite me and he is holding a couple of balls as it goes. There's also a little table that's been setup so, what are we going to do with these two objects?

Hugh: Right. The bouncy ball, I've got here, I'll throw it under the table, and it's going to bounce three times - once on the floor, once under the table and then back on the floor again and here I go.

Diana: Ahh! So you threw that in my direction towards me and instead of coming out towards me, it's gone back to you.

Hugh: Absolutely.

Diana: So, what has happened? Why, this isn't right.

Hugh: It isn't right. It doesn't seem right, but it is in fact exactly what you would expect to happen if you sit down and think about it. The first thing is, imagine just what happens to the ball after it bounces on the ground. So, if you've got a friend, just bounce the ball towards that friend. I'm bouncing this ball towards...

Diana: Okay, so he's got a slightly larger ball here which hopefully will bounce a bit slower. Throw that towards me.

Hugh: Yeah and I'm bouncing it towards Diana.

Diana: Yup!

Hugh: And what did you notice, Diana?

Diana: Okay it was spinning as it sort of came to me.

Hugh: Alright. Well I didn't - it wasn't spinning when I threw it.

Diana: No.

Hugh: It's spinning after it hits the ground. It's coming in at an angle on the ground, it starts to spin. Now that's what you expect if a plane is coming to land and the wheels are not spinning. What the wheels do immediately as they touch the ground? They start to spin. Well why shouldn't the ball start to spin? Right, now I've got a spinning ball and it's heading up towards the underside of the table. Well we all know that if you've got a ball with a bit of spin on it, you know, Shane Warne and some of the best ever bowlers. I better not talk about cricket, but never mind.

Diana: Yeah, we've only got a few minutes on this.

Chris: Well talk about tennis because that's okay.

Hugh: Yeah, but there are athletes trying to play tennis aren't they? So you put some backspin on the ball and to see after backspin on the ball.

Diana: Yeah, it bounces back towards you.

Hugh: Yeah and in fact with top spin on the ball, then it - now it's heading towards you. So, the idea is you throw the ball on the floor. It starts to spin. Now that it's got some spin, it's backspin on the underside of the table, it's like coming back towards me. And it's one of these great things that if actually stop and think about it step at a time, it makes perfect sense.

Diana: I see, so what are the real world applications of this then?

Hugh: Well, applications are a bit hard to find but understanding spin is very important - gyroscopic effects and all that, but there was an episode in 2010 in the World Cup. Frank Lampard's gold was disallowed. It's exactly the same as this because if you look at the replays of it, the ball hit the crossbar, started to spin, went down, hit the ground inside the

goal, but because of the spin it came back out again.

Diana: So that was just enough to confuse the linesmen and the referee.

Hugh: Yeah, and maybe really go...

Chris: They're going to put the new technology into the stuff.

Hugh: Well, the new guideline technology should with any luck and pick that up.

Diana: Yeah.

Chris: Because I mean, the same science is manifest - I know I said tennis and you said, "Well, there's no (55:01)." But the thing is, when you see those balls go flying through the air and then they suddenly just nosedive just inside the touch line and the person has got it when (55;13) and the person then scores this point and then says, "I want to appeal this!" that's just the same thing, isn't it?

Hugh: Well, it's kind of different. I mean, the spin in the air is this Magnus effect which is the effect of aerodynamics, pushing the ball down if you've got topspin and hovering the ball up if you've got backspin. Now the impression is that it suddenly, but it's just that the ball is coming down at faster than G because of the topspin and down force due to Magnus effect. It's very deceptive and that's, well I guess what are good tennis player is doing is trying to create motions on the ball that deceive you.

Chris: But one other point I did here, some will make about this is that when the ball is traveling really fast, the air can't stick to the surface very well because of turbulence whereas when it slows down a little bit, then the air finds it easier to stick on and then this Magnus force kicks in and it pulls the ball down because of the spin and then it nosedives really quite dramatically and you've got 15 seconds to come back at me on that.

Hugh: It's certainly true that speed make a big difference and we know about swing on a cricket ball, reverse swing and so on. It's very sensitive to speed, humidity, all sorts of things.

19:18 - The lies have it: no evidence for lie-eye-movement link

The claim that people tend to look in one direction - up and to the left - when they are being honest, and a different direction - up and to the right - when they are lying, turns out not...

The lies have it: no evidence for lie-eye-movement link

The claim that people tend to look in one direction - up and to the left - eyeswhen they are being honest, and a different direction - up and to the right - when they are lying, turns out not to be true.

The suggestion that gaze-direction is a dishonesty giveaway is one of the tenets of "neuro-linguistic programming" (NLP), a collection of psychological techniques that, among other things, aim to enhance an individual's communication skills.

Practitioners are taught that, when right-handed people are visualising made-up events in their mind's eye, they tend to look upwards and right. Recalling a real memory, on the other hand, is claimed to be signalled by a look to the upper left.

These claims are based on work in the 1960s by the psychologist Paul Bakan, who suggested that activity one part of the brain could sometimes spill-over into an adjacent region called the lateral eye field, which coordinates eye movements, provoking a look in one direction or the other.

But subsequent studies on this work painted a shaky picture, so University of Hertfordshire researcher Richard Wiseman and his colleagues have carried out a series of 3 "blinded" experiments to comprehensively test whether individuals really do "look shifty", or at least away from the left, when they lie.

In the first experiment, the team asked student volunteers to take a mobile phone and either conceal it about their person, or put it in a drawer and then convince an interviewer, regardless of what they'd done, that the phone was in the drawer.

As they related either the lie or truth, they were filmed. Their eye-movements were then logged, which revealed no bias in gaze direction, regardless of whether they were telling the truth or not.

In a second experiment, to determine whether training in NLP techniques somehow makes individuals more sensitive to picking up porkies, the team asked a second group of volunteers who had been previously primed about what to look out for, to review the films from the first experiment.

Although the raters who received the NLP training reported greater confidence in making judgements about lies or truth-telling, they were actually no more accurate than a group of untrained controls.

Finally, to test real-life examples of high-stakes lying, to see whether this might make a difference, the researchers analysed 52 video sequences of relatives making public pleas for the safe return of a missing relative. But in half of these cases, the person was subsequently proved to have been lying. These individuals showed no biases in their gaze directions either.

According to Wiseman and his colleagues, "These results provide considerable grounds to be skeptical of the notion that proposed patterns of eye-movements provide a reliable indicator of lying. As such, it would seem irresponsible for such practitioners to continue to encourge people to make important decisions on the basis of such claims."

23:45 - The galaxies that have no stars

Astronomers using the Very Large Telescope in Chile believe they have made the first ever observations of galaxies that have no stars in them.

The galaxies that have no stars

Astronomers using the Very Large Telescope in Chile believe they have made the first ever observations of galaxies that have no stars in them. Writing in the Monthly Notices of the RAS, Sebastiano Cantalupo's team report the discovery of 98 such galaxies, clustered around a bright quasar at a distance of 11 billion lightyears away from the Earth.

These so-called "dark galaxies" fill a gap in theoretical models of how galaxies form, as Martin Haehnelt explained when I spoke to him this week in his office at the Kavli Institute for Cosmology in Cambridge: "We have a standard model of how galaxies form, and there are predictions that we are very confident about that there should be galaxies that are much smaller than are easily visible."

The problem is that the theoretical models predict that stars form so efficiently in the early Universe that galaxies quickly run out of gas to make new stars.

By contrast, there is strong observational evidence that stars formed in the Universe over a prolonged period of 5-10 billion years after the Big Bang, and still continues now, 13.8 billion years later, albeit at a much reduced rate.

Dark, starless, galaxies solve this problem by acting as reservoirs of gas which eventually collide with larger galaxies, providing fresh new gas for later star formation.

"I wouldn't call them failed galaxies", says Haehnelt. "They're slowly developing galaxies and they're the infant stage of bigger galaxies. They will be incorporated later into more normal galaxies."

The difficulty has been working out how to detect galaxies which don't contain any stars. Astronomers usually rely on the radiation from the hot surfaces of stars to light galaxies up. Dark galaxies, by definition, aren't illuminated by any starlight.

"We were looking for another light source... to light them up like a torch", explained Haehnelt. The light source the team chose was a distant quasar, one of the most luminous known objects in the Universe.

It was also at around the right distance, 11 billion lightyears away, to probe the Universe at a time when dark galaxies were thought to be very numerous, 2-3 billion years after the Big Bang.

What the team observed in their 20-hour observation with the Very Large Telescope was the very faint fluorescence of 98 clouds of hydrogen gas, which were being excited by the intense ultraviolet light of the quasar, but which otherwise produced no detectable optical starlight.

For the first time, these dark galaxies are not just a theoretical prediction, but objects that can be observed and measured to test the ideas that cosmologists have about how galaxies have formed and evolved over cosmic history.

The 98 objects seen thus far are all in the same neighbourhood around a single quasar, but given the success of this first observing run, Haehnelt tells me that he's very hopeful of repeating the experiment around other quasars to see how other neighbourhoods compare.

26:48 - Chemical Cocoon: Preserving Drugs in Silk

Antibiotics and vaccines save lives, but to do so, they usually need to be kept cold and this could be a bitter pill to swallow for 3rd world countries that can't afford the necessary...

Chemical Cocoon: Preserving Drugs in Silk
with David Kaplan, Tufts University

Chris -   Antibiotics and vaccines save lives, but to do so, they usually need to be kept cold and this could be a bitter pill to swallow for 3rd world countries that can't afford the necessary refrigeration, despite having the most to gain from these treatments.  But now, that might be about to change, thanks to a breakthrough by Tufts University scientist, David Kaplan.  He's discovered that wrapping vaccines and antibiotic molecules in a layer of silk can keep them in pristine condition for months, even at temperatures above 40 degrees C.

David -   My lab has studied silk for over 20 years, so we've gotten to know the protein very well.  We've learned how to clean it up, how to purify it, and how to use it in medical devices, and medical materials of all kinds.  As a result of that, we've also studied the ability to put things like enzymes into silk and show that they're inherently very stable under those conditions.  That led us to hypothesise if an enzyme, which is a protein as well, is stable in silk, perhaps there's broader utility to entrap and stabilise other molecules like vaccines where there's a real need and a real challenge.

Chris -   When we say silk, it implies a scarf or a tie or something.  Are we really talking the same stuff that you would weave into a silk scarf or a silk tie when you're doing your work?

David -   Yes and no.  We're certainly talking about the same source material.  So the material we start with comes from the textile world and that's a great thing because that means there's a huge supply of the material available which makes the cost relatively low.  The downside is you would never introduce textile silk into the human body.  You'd have severe problems with inflammation and you would have difficulty.  And so, to use the silk, we and others have learned over the years how to get rid of all the proteins on the silk that otherwise would cause inflammation.  When you do that properly, you have a very nice material that's compatible with the human body and in fact, it's been used and FDA approved in a number of medical devices already.

Chris -   So, you don't get reactions with the immune system for example?  It's a foreign protein so you'd think if you put that into the body that the body would recognise that as not part of it and you'd get a reaction.

David -   That's right and yet, the reactions are very, very tepid and so, you don't see any kind of major problems that you'd expect.  In fact, all the studies published around the world from our lab and others always show that of all the approved degradable polymers used in medical materials, silks always tend to be the lowest in terms of any inflammation or immune response.  So, it has to do with the chemistry of the silk.  It's a very hydrophobic molecule.  It has to do with the fact that it degrades in the body very slowly and I think this combination of features helps to give this very low response.

Chris -   So what did you do?  You took some silk that have been prepared in the way you say and then mix them with antibiotic or even viruses to see what the silk will do.

Silk cocoonDavid -   That's correct.  We create solutions of the silk protein in water and once you have that, we can add in essentially  any bioactive molecule that you would like.  In this study we showed that with vaccines and antibiotics.  Then you have to process that solution into a stable material format and it can be in a form of a film, it can be in the form of a fibre, a gel or we make things like micro needles, sort of like a band aid that can administer through the skin.

Chris -   When you do that, what impact does it have on the stability of the agents that you invest in silk in this way?

David -   A remarkable improvement in stability, not just under refrigeration conditions, but even at temperatures as high as 45 degrees centigrade and even over 6 months, they still retain the far majority of the activity of these vaccines which is quite remarkable I think.

Chris -   Compared with had you not had the silk there, the activity would by that time have just gone to zero.

David -   That's correct.  You would've lost all activity.

Chris -   Do you know how it works?

David -   In the paper, we also discuss a little bit on the mechanism and in brief, what we find is there's clearly some interactions between the silk protein itself and the proteins on - in this case - the inactivated virus that we use that appears to essentially pin the protein together and prevent it from denaturing or aggregating, and losing bioactivity.  That's coupled with the low water content in the silk.  And then the last point is that silk is dominated by these very, very small nanoscale hydrophobic domains.  We call these beta sheets.  These are the crystals.  And because they're very, very small, there's lots of interfaces, lots of room for vaccines and other molecules to pin up against these structures and become immobilised and less prone to be inactivated.

Chris -   It sounds like a pretty awful example for me to give to you especially when we're talking about medical things, but I've won enormous amounts of money in bars by betting people I can bend a cigarette so that one end would touch the filter end and the way you do it is by wrapping it in a 5 pound note and having the investiture of the note around the outside of a cigarette means you can make it do unfeasibly bendy things.  Are the particles that you're putting into the silk, are they effectively being stabilised by this enwrapping or this sheathing in the silk, and that just stops them falling apart?

David -   It's two things - one is exactly what you say.  I think it prevents them falling apart or falling into the mis-shapen form so they're no longer active and the other is it prevents them from aggregating too much because there's not a lot in one spot.  So I think that combination helps a lot.

Chris -   How do you get the particles away from the silk again?  So when you actually want to use the antibiotic or you want to metaphorically smoke the cigarette, when you want to administer the vaccine or whatever, do you need to get it away from silk or is that not necessary?

David -   There are many options.  There are three we most commonly talk about:  One is, you can resolubilise the film with the vaccine in it and inject that and silk has been injected before.  It's safe to use.  There need to be more human clinical trials done, but that would be the easiest format and I think that would be very attractive.  If you don't want to do that, you could certainly solubilise and then separate the vaccine from the silk.  And the third, which we happen to like the best, would be when you fabricate the films, you fabricate them in these micro needle formats that I mentioned before and these become essentially a film, like a band aid strip with little pin pricks on one side so you can simply put that on your skin and the vaccine would then get through the skin based on the dissolution of the silk under the skin.  So you never have to separate it from the silk.  You can just use it as is, as an intact device.  And so, that's very attractive because that's something you could ship around the world and then use on demand.

Chris -   Isn't that amazing?  You can put these things viable for months at higher than body temperature just be mixing them with some silk.  That was David Kaplan from Tufts University in the US and he published that work this week in the journal PNAS.

33:56 - Could red shift just be the colour of the star?

Could red shift just be the colour of the star?

Dominic - Stars certainly do come in wide variety of colours. Hotter stars will tend to be bluer than cooler stars like Betelgeuse which are comparatively red. But when you're looking for the red shift, looking at the frequency shift which is associated with the velocity of that star, what you're looking at are spectral lines. These are very specific wavelengths in the spectrum of that star where particular elements produce light in a very small range of frequencies and this produces a bump in the spectrum which is always in exactly the same place. And what you see when a star is red shifted is that characteristic bump is shifted to a different frequency. You can be sure it's the same bump you're looking at because they form a pattern across the spectrum of different elements emitting different wavelengths. Chris - So, you basically know if your hydrogen bump is shifted a little bit that it's definitely hydrogen, and that's just offset by certain amounts and the amount is going to be offset by is proportional to the amount the star has been red shifted or blue shifted, and that tells you how fast it's moving away from us. Dominic - Exactly, yes.

35:23 - Is there a gene for liking marmite?

Is there a gene for liking marmite?

Diana - I'm going to say that I'm ambivalent towards marmite in small quantities. Actually, there is a gene which determines how sensitive people are to compounds called phenylthiocarbamide and propil thiouracil. You find these bitter compounds in things like cabbage and grape seed. Now some people are very sensitive to these bitter compounds and some can't taste them at all and this is genetically determined. Apparently, it's sitting somewhere on chromosome 7. It's thought that maybe the people who can't take these PTC- like compounds are very sensitive to bitter things like grapefruit, tea, coffee, as well as cabbage and other cruciferous vegetables. So, it may be that Marmite is related. It's got that bitterness element in it.

36:24 - How can photons impart momentum to objects?

How can photons impart momentum to objects?

Dominic - This is actually a very common misconception because at school, of course, you're taught a lot of Newtonian physics where something without mass can't exert a force. It doesn't have momentum. But, in fact, a photon is a relativistic particle; and in relativity, energy and mass are equivalent to another. So, although the photon doesn't have any mass, it has momentum still, which is associated with its energy and that's significant because the photon is traveling at this relative speed of the speed of light. Einstein's theory of relativity has completely taken over from Newtonian physics. And that explains how the photon can have this momentum which it can impart to an asteroid...

37:28 - What is the origin of circumcision?

What is the origin of circumcision?

Chris - Trish in King's Lynn has got in touch and pointed out that there are various aspects of the Jewish faith, with it being carried out on the 8th day after birth because coagulation factors have peaked by then. But if we look further back Diana, what have you flushed out? Diana - Well it looks like circumcision has been attested historically, at least among the Egyptians, and that would have been around the 3rd Millenium BC. It seems to be to do with cleanliness. A few Millennia later, Hereditas was writing about the Egytpians and he described it as a right of passage marking the transition from childhood to adulthood. Perhaps the meaning of circumcision had changed by then. I think the fact that different people in different parts of the world were practising circumcision implies it might be something that's gone on far longer than our historical records imply. Unfortunately the evidence doesn't fossilise well! Chris - Today, we continue to discover things about this. It's been shown to have a dramatic effect on HIV - an 80% reduction in risk. The same benefit transfers to HPV which causes cervical cancer, penile cancer and warts.

37:59 - Clearing away Huntington's, Altruism in the brain and a Fatally Falling Batman

How proteins could help clear away Huntinton's disease, a new homeostatic material, defining altruism in the brain and why batmans cape isn't coming t the rescue...

Clearing away Huntington's, Altruism in the brain and a Fatally Falling Batman
with Albert La Spada, UCSD; Joanna Aisenberg, Harvard University; Yosuke Marashima, University of Zurich; David Marshall, University of Leicester

Clearing Away Huntington's Disease

Two proteins have been identified to fight and potentially treat the neurodegenerative condition, Huntington's disease, according to research inHuntington the Journal Science.

Patients with the condition have a gene mutation resulting in mis-folded forms of the protein Htt, which builds up in their central nervous system causing the progressive deterioration of involuntary muscle control, and cognitive decline.

But now, Albert La Spada from the University of California, San Diego has found that elevating levels of the proteins PGC1-Alpha and TFEB, helps clear away mutant forms of Htt preventing their build up and resulting neurotoxic effects.

Albert -   There are features of Huntington's disease that are shared by more common neurodegenerative disorders like Parkinson's diseases and so, if we can develop therapies based upon these strategies, they should not only be applicable to Huntington's disease, but also be applicable to Parkinson's disease, and perhaps other neurodegenerative disorders.

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Some like it Hot

Smart materials with the ability to regulate their temperature have been developed by scientists at Harvard University, publishing in the journal Nature.

Modelled on the process of homeostasis in the human body whereby body temperature is maintained at 37 degrees, these homeostatic materials consist of a surface gel layer sensitive to the temperature of its surrounding environment which in response to a drop in temperature, activates the movement of catalyst-containing structures into a second reactant layer where the catalyst initiates an exothermic reaction - causing the release of heat.

When the required temperature is restored, the catalyst is removed and the reaction stops.

Joanna Aisenberg led the team who hope to use the technique to control a wide range of environmental conditions.

Joanna -   The prototype material shows that we can maintain a constant temperature.  But in fact, the same strategy can be adapted to create materials that maintain constant glucose levels in the bloodstream or pH in water supplies.  We're really thinking now of a whole range of materials that are capable of autonomous self-regulation.

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How the brain decides altruism

Altruistic Individuals have more grey matter in the region of their brain responsible for empathy.

Writing in Neuron, Yosuke Morishima form the University of Zurich used fMRI techniques to monitor brain activity in human volunteers as they answered questions about splitting money between themselves and others. His team found that the volume of gray matter found a region of the brain known as the temporo-parietal junction and the level of activity there,  was a strong indicator of how altruistic an individual would be.

Yosuke -   When we look at other people we can't tell whether that person either denies or either generous or selfish.  But our study would partly tell us about an individual's private influence which cannot be transparent.  And also, some behavioural studies have shown that people who are living in really large societies tend to behave more altruistically compared to the people who live in a small societies.  Maybe we might be able to elucidate the cultural influence of brain and on our behaviours.

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Not Enough of a Caped Crusader

And finally, the cape used by well-known superhero batman to glide from tall buildings, would, in reality, send him crashing to the ground at high speed.

Physics students at the University of Leicester calculated that the 4.7m wingspan of the cape seen in the recent films by Chistopher Nolan, which becomes rigid as an electric current passes through it, isn't big enough to enable the caped crusader to glide to safety when jumping from a building 150m high.

In fact, the team led by David Marshall worked out the hero would hit the ground at 50 mph.

David M. -   Batman's cape is maybe not as effective as it could be just because it's too small.  When you look at it compared to a hand glider, it's about half the size that it needs to be so it keeps batman aloft.  It's okay for moving, he can get to about twice as far as you can fall which is sufficient for getting between buildings, but by the time he gets there, he'll be traveling around about 50 miles an hour.  So, there's a few different ways that he could fix this by getting a bigger cape, or we need some sort of active propulsion system such as jet packs.  Really, Batman needs to find some better way to do with this.

The paper "Trajectory of a Falling Batman" was published in the University of Leicester Journal of Special Physics Topics.

42:41 - Neanderthal Cave Art - Planet Earth Online

Back in time now almost 50,000 years to the final days of the Neanderthals and the rise of modern man. Research has revealed the oldest known cave art in Europe, and it might not have been...

Neanderthal Cave Art - Planet Earth Online
with Alistair Pike, University of Bristol

Chris -   Back in time now almost 50,000 years to the final days of the Neanderthals and the rise of modern man.  Research - published in the journal Science - has revealed the oldest known cave art in Europe, and it might not have been painted by humans.

Richard Hollingham has been to the University of Bristol to talk to the archaeologist who led the project, Alistair Pike.  As they didn't have a cave handy, Alistair projected the art onto a wall of the lecture theatre so they could get an idea of how it looked...

Alistair -   We're looking at the panel of hands - it's part of a cave called El Castillo cave in Northern Spain, very close to Santander, and this part of the cave maybe 41,000 years ago was decorated by people putting their hands against the cave wall and then blowing or spitting pigment to create these negative hand images.

Richard -   How old are these?

Alistair -   Next to the handprints there are some red dots and one of those red dots is at least 40,800 years ago but because we can see that they were made in the same technique, they don't overlie each other we think actually the handprints were made at the same time.

Richard -   What does that mean then? It sounds an awful long time ago but that has particular significance.

Alistair -   Yes, well first of all it is at least 15,000 years older than we previously thought the art in this cave to be but it dates from around the time when modern humans first arrived in Europe and the Neanderthals begin to disappear, but because we're dating these deposits on top of the art we don't actually know how old the art is, all we know is that it is older than 40,800 and therefore it might have been made by Neanderthals.

Richard -   Would that have been their first?

Stone Age Cave Art - Panel of HandsAlistair -   Absolutely, or certainly paintings - first example of Neanderthal paintings, so you can look at the fingers, the hand prints of Neanderthals if indeed this is the case.  But we do know that Neanderthals maybe 50,000 years were making art-like objects in other parts of Spain, so we find things like shell beads to use for body adornment, we find shells that have traces of pigment in them that look like they might have been used as a sort of cosmetic even.

Richard -   So once again Neanderthals turn out to be a lot brighter, a lot more advanced (and I know archaeologists hate using the word 'advanced') than that we first perhaps thought.

Alistair -   Well if this genuinely is Neanderthal art, and we haven't yet proved it beyond all doubt because conceivably it could have been made by modern humans a matter of a few hundred years after they first arrived in Northern Spain, but if it does turn out to be Neanderthal then it is showing that Neanderthals have the cognitive abilities rather similar to modern humans, so we've narrowed the gap and the difference between them.

Richard -   But even modern humans when they started turning up in Europe, they didn't have a culture of art before that - is that right?

Alistair -   Well that's a very interesting question because in fact in Africa we do find art objects around 70,000 to 100,000 years ago, which include little bits of engraved red ochre minerals. We find beads, bead necklaces and we find engraved ostrich eggshells but the earliest paintings in Africa are only around 25,000 to 27,000 years ago.

Richard -   So a lot more recent than the ones here, for example.

Alistair -   Absolutely, so it looks like the tradition of painting caves started in Europe and that is a really interesting question to ask why should it be that humans should start painting caves in Europe and not in Africa when they have been making art objects in Africa for the previous 50,000 years. We think we've got an idea about why this is and that is, actually, the presence of Neanderthals.  Just after humans arrived in Europe we find the first examples of musical instruments, of figurative sculpture, we may have found the first example of painting and the difference between Africa and Europe at this time was the presence of Neanderthals.  So it might have been that in order to compete for resources with Neanderthals, modern humans had to organise themselves differently, socially, and art may have been one of these innovations that allowed them to create a group identity and therefore compete with Neanderthals.

Richard -   So we look up at this image projected on the wall of the lecture theatre here - you've got these hand prints and this shadowy image of a bison or something and concealed by this calcium deposit over the top.  How on earth do you go about finding out the age of this without damaging it?

Alistair -   Well, the key to actually being able to date these things is that calcium carbonate deposit that you mentioned.  We can use the radioactive decay of uranium which decays to thorium to work out when these things are formed and it is the measurement of the thorium to uranium ratio that tells us how long, how much time has passed since the precipitation of calcium carbonate and since these are formed on top of the paintings we know they must have been older than the dates that we are measuring.

Richard -   So, actually, it is relatively straightforward thanks to the material that's obscuring them?

Alistair -   Absolutely.  Some people might think it is a shame that you can't see all of the art but it's thanks to that layer that we can actually obtain age information about the paintings.

Richard -   Now, we talk of this as pre-history but I suppose this was the first history particularly as people came back, it's a record really of humanity.

Alistair -   Absolutely, and there's some studies that have actually looked at some of these symbols and they find groups of them reoccurring in different caves all over Europe, so in fact we might be looking at a form of language here.

Richard -   So really this is the start of so much.

Alistair -   It's the beginning of the modern period for humans if you like.

50:12 - Why is copper so good at conducting heat?

Why is copper so good at conducting heat?

Dominic - It's all about having charge carriers in the metal which can conduct both electricity and heat. So, if you put energy into those, they flow through the metal and conduct both heat and electricity through it. Chris - So if something has got electrons, like copper, loads of them that can move around very freely, when you make it hot they're going to vibrate a lot and move around carrying those vibrations and transmitting those vibrations i.e. heat through the material in just the same way as they would migrate in an electric field. Dominic - Exactly, they're not bound atoms, they can move all the way through the material.

55:29 - Can you get sick from your own intestinal bacteria?

If the bacteria that cause a bout of food poisoning came from your own intestines, will you be protected against illness?

Can you get sick from your own intestinal bacteria?

Hannah - So, can your own bowel bugs make you sick or can only make other people sick?

According to Professor Liz Sockett at Nottingham University, the mucosal lining of your gut contains immune cells which make antibodies which will attack and neutralise specific bacteria. The immune system will remember seeing the specific bacterium if it re-infects. So for the second exposure, the immune system will probably neutralise and kill the bacterium before it can multiply sufficiently to cause disease. But some food poisoning isn't caused by the bacteria growing in the individual, but by the toxins produced by bacteria in food that has been poorly stored. The toxin damages your intestinal wall lining so quickly that you haven't got the time to mount an immune response to protect yourself. So, immunity cannot protect you and you could show symptoms on repeat exposure to the toxin.

Staphylococcus Aureus for example which can be found on the skin where it causes boils and spots, if that gets into poorly stored food, produces toxins which are heat and acid stable. So, the bug may not survive in the cooking process and the acid environment in your stomach, but the toxin does, and it can poison your intestine, causing diarrhoea and vomiting.

Harry Flint, Professor of Rowett Institute of Food and Health at Aberdeen University explains. Harry - Intestinal damage and diarrhoea caused by the huge quantities of toxin present in the food, and produced by the bacteria multiplying in the food, can affect you even if you have acquired immunity to the bacteria.

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