Nature Podcast 15 June 2006
Introduction
This is a transcript of the 15 June edition of the weekly Nature Podcast. Audio files for the current show and archive episodes can be accessed from the Nature Podcast index page (http://www.nature.com/nature/podcast), which also contains details on how to subscribe to the Nature Podcast for FREE, and has troubleshooting top-tips. Send us your feedback to mailto:podcast@nature.com
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Chris Smith: This week, why those that hate each other, under certain circumstances, will still stick together, the trials of Nature, why this journal is testing a radical rethink of the scientific publication process. Well also be lacing up our boots for a look at the science of soccer, finding out how new animal species come about, searching for your inner gambler and introducing the world's strongest glass; its made of carbon dioxide. Hello, I'm Chris Smith and welcome to the 15th June edition of Nature's podcast. First up today were taking to the air with Reading University's Nicola Stuber to find out why cheap flights actually cost the Earth and that's especially at nighttime and in the winter. It's all down to their contrails, those fluffy white exhaust fumes that planes leave behind them. Nature 441, 864–867 (15 June 2006)
Nicola Stuber: We discovered that flights during the nighttime are responsible for at least 60% of the climate warming associated with contrails, that's condensation trails, over the UK. That's despite the fact that they only amount to 25% of the daily total of flights. And the second thing we found is that flights between December and February cause about half the climate warming associated with contrails over the UK and so we get one half of the climate effect from just one quarter of the year and, actually, less than a quarter of the annual air traffic.
Chris Smith: Now that sounds like a lot, but do the contrails actually make a significant difference to global warming?
Nicola Stuber: The effect is currently small but air traffic has a large growth rate and is expected to grow quite significantly over the next years, so it's, actually, quite important to understand the mechanisms and how it affects climate.
Chris Smith: This is just, literally, the exhaust coming out the back of a plane, isn't it?
Nicola Stuber: Well, contrails is short for condensation trails, to they form when the hot and moist aircraft exhaust mixes with the cold, surrounding, atmospheric air.
Chris Smith: So how do they influence weather?
Nicola Stuber: They act like high thin ice clouds, so they interact in two ways with solar radiation. They reflect some of the solar radiation back into space and it has a cooling effect on the Earth and, at the same time, they enhance the natural greenhouse effect of the atmosphere, and that's a warming effect.
Chris Smith: Why are the nighttime and wintertime so much worse though?
Nicola Stuber: The problem is that contrails, as I said, during the day they reflect some of the solar radiation back into space and that leaves us with a cooling effect of the Earth and then, during the daytime and during the night time, they enhance the natural greenhouse effect of the atmosphere. So the problem is, at night time, you no longer have sunshine so they no longer can reflect solar radiation so the warming effect, the greenhouse effect, of the contrails is no longer balanced and that's why a small proportion of flights results with a large impact of the daily average climate warming effect, due to contrails.
Chris Smith: So, given that a small part of the day and a small part of the year, in total, make such a profound contribution, do you think, therefore, we should be changing when aeroplanes fly and at what time of year?
Nicola Stuber: Rescheduling flights would certainly be one measure to think about if policy makers decided to reduce aviation, reduce climate change. Its not the only measure we could do, you could actually try to avoid forming contrails, so I think it's a combination of different measures, but rescheduling flights would have an impact really.
Chris Smith: Nicola Stuber from the UK's Reading University. Now most of us stay as far away as possible from the people we loath and we thought that atoms did pretty much the same thing. But the University of Innsbruck's Johannes Hecker Denschlag and his colleagues have used a laser beam to sort a cluster of ultra-cold rubidium atoms into the optical equivalent of an egg box. Under these ultra clean conditions the rubidium atoms will form stable pairs, something that have been predicted, but never observed. Nature 441, 853–856 (15 June 2006) ; Nature 441, 820–821 (15 June 2006)
Johannes Hecker-Denschlag: What we have discovered was that if you put two atoms into a special environment which is, in our case, an optical lattice, and you put them together, although they repel each other, so they don't like each other, they will still stay together.
Chris Smith: In what way does that build upon our present knowledge, was that not known before, that they could do that?
Johannes Hecker-Denschlag: To my knowledge, this has not been observed before. This has been, perhaps, predicted. You know, I can give you a picture which could be illustrating what's happening. So imagine two objects or two people that really hate each other. And, so, if you put them close to each other and you let them, basically, go. In free space what happens is that they just separate quickly from each other and they run off. Now, in our case, we put these two things together that really don't like each other and the more they don't like each other, the more they stay together. That's the mystery that appears. Now in the end, it's not all that complicated to understand, once you understand physics, but for our everyday life it's strange, and it hasn't been seen before.
Chris Smith: So what's the bottom line, why does that happen, then?
Johannes Hecker-Denschlag: The bottom line is that we have a very clean system where, once we have, like, put energy into the system, it's very difficult for the pair to dissipate this energy. Now in order to separate they have to dissipate this energy, they have to, kind of, get rid of this hatred energy, I would say, and there is just no way they can do this, so for this way, they have to stay together.
Chris Smith: How did you actually do the experiment though, because we're talking about individual atoms here, absolutely tiny, how are you doing this?
Johannes Hecker-Denschlag: So imagine you have a tiny cloud that has a diameter of about 100 microns or so, of a couple of hundred thousand ultra cold atoms. And we put these atoms into some kind of an egg-crate, which we call optical lattice, this is formed with laser beams and, what happens then if we do this carefully, the atoms will hop around in this lattice and redistribute themselves in a very ordered way and we can make them go into different lattice sites so that only one atom, two atoms, or three atoms sit in a particular lattice site.
Chris Smith: And once you've got them in there, then you actually start doing your studies, but how are you measuring what the atoms are actually doing, how do you watch them?
Johannes Hecker-Denschlag: Yeah, our measurements work that we just look at numbers of atoms and we can distinguish between pairs and single atoms because we have developed a method, how we can blow away the single atoms and preserve our pairs of atoms in the optical lattice and the trick that we use is that whenever we have a pair we can convert it, very efficiently, into a molecule, a real chemically bound molecule which is unaffected by our laser beams that blow away the single atoms.
Chris Smith: So you've got to the bottom of the fact that these two atoms stick together, but what's the next stage here, what's the next step that you need to explore?
Johannes Hecker-Denschlag: Well there is now a number of questions, for example, how stable are these repulsively bound pairs in reality? So, if they really collide with each other, with how many pairs can you collide them at the same time, and they still will survive?
Chris Smith: The University of Innsbruck's Johannes Hecker-Densclag showing, for the first time, that repulsive pairs of atoms can form a stable partnership.And now a look at the journal Nature itself. And more specifically, at the process of peer review. At the moment, leading authorities are invited to comment, anonymously, on submitted manuscripts. It's a method of error checking, it gives credibility to the published work and it helps editors to reach a decision about what should and what shouldn't be published. Indeed, it is viewed at the gold standard and used by journals worldwide. But are we missing a trick with this process, just because it seems to work quite well? Could it, in fact, be improved? Well, to find out Nature is launching a trial of open peer review and to explain how it's going to work, here's Nature's editor and chief, Dr. Philip Campbell. http://www.nature.com/nature/peerreview/index.html
Dr. Philip Campbell: It was in the early 60s when Nature first introduced what we now call peer review. And ever since then we've stuck to, pretty much, a consistent approach, to assessing the papers that are sent into Nature for publication. We reject a high proportion of them immediately, based on purely editorial judgements, but then there are the important papers that we send out for peer review and that, usually, is about two people or three people of different expertise who look at a paper and advise the editors, who then make the final decision, based on that technical advice and the technical perspective that those peer reviewers bring to the process.
Chris Smith: So what are you going to do to shake the system up?
Dr. Philip Campbell: The system does work but there are ways in which you might benefit by throwing a submitted paper open for public comment before you decide to publish it. So that's what we're going to do. Every paper that comes in, where the authors say that they're happy to go down this route, will be subjected to our normal peer review process, but at the same time we'll post it up on an open web server and anyone who wants to comment can do so. People, who we haven't thought of, to assess a paper, could make some interesting comments that the editors and the authors would value. We'll do some, very obvious, moderating in the sense that we'd keep away from anything libellous or anything obscene, but otherwise it's anything goes and then it's up to the editors to take on board the public comments and then discuss those with the authors. It's possible that you can really benefit from a system like that.
Chris Smith: And what's provoked you to consider even doing this in the first place? You've got a very good system; it works incredibly well, as far as we know.
Dr. Philip Campbell: There is a sense of disquiet out there, about the closed nature of peer review. People will say you guys who just publish things that you know are from the big labs and if you get a letter submitting a paper from a lab you've never heard of, you won't publish it. Which, I know, is nonsense, because we really do not have that sort of cronyism going on in our offices. But there is very much a perception out there, that there are problems in the process and, I guess, just by exploring this we can, possibly, find ways that, in the long run, will get rid of some of those concerns.
Chris Smith: What about the competitive angle here, because people are obviously sending extremely hot material to you at Nature, are they going to be entirely happy to see this put on the web, I mean, obviously they've got to sign up and agree to it, but how do you think they might view that?
Dr. Philip Campbell: It's very hard to anticipate how people are going to respond, with that in mind. If you think about the physics community, they've had pre-print servers in place for some time and those are servers where they are able to put their pre-prints up on the web and anyone can comment on it. And, indeed, colleagues have told me that they've really benefited from the informal comments that they get, sometimes from their competitors, in a collegial spirit. But I think it's also true to say that there are some very competitive fields where the authors are unlikely to put up their papers, because people can see those results and react, so they may have a very similar result being considered by another journal and it would give them a cue to go to that journal and say please, please hurry up and publish this thing.
Chris Smith: And once it actually does come in, assuming that it's a success and you introduce this, is it still going to be an opt out system? So some people will be able to do it, some won't. Or are you going to say right, it's in for a penny, in for a pound, everyone does this?
Dr. Philip Campbell: At the end of the trial we will evaluate all the comments that we've received and try and form a judgement as to whether it's really added value to the process and then, if it does, we might go ahead and change our process in the sense of opening it up, while maintaining the traditional approach. But I can't imagine we would compel people to do it because I can think of reasons that people might feel really concerned about exposing their work prematurely. And I think we should respect that.
Chris Smith: Editor and chief, Dr. Philip Campbell, explaining to me how Nature's planning a fairly radical shake up of the peer review process. And now to a game that, like many others, we invented here in England and the rest of the world now delight in beating us at. It's of course World Cup season. And, as they say, it always pays to keep an eye on the ball and when it comes to football scientists are certainly no exception. Kicking off for Nature, here's Mike Hopkin. http://www.nature.com/news/specials/worldcup/index.html
Mike Hopkin: Fans watching their team in the World Cup this month will be hoping that they don't concede a shed load of goals, but it's always a cliché that, once the floodgates are opened in a match, particularly when one team is dominating, that that will lead to a very heavy defeat for the side that concedes the first goal. Some mathematicians have proved that it is actually true.
Chris Smith: What do they suggest is a reason why this happens, Mike?
Mike Hopkin: They're suggesting that the statistics support the theory that one team gains a lot of confidence from scoring a goal, that a team that concedes a goal, their heads drop, they lose morale and the other team can press home the advantage. And a lot of people thought that was a just a myth or something that coaches used to say to their players, but it seems that an analysis of statistics from the German Football League and from the World Cup matches over the years, have proved that it is, actually, a phenomenon.
Chris Smith: I suppose it's quite similar to the concept of playing home versus away, isn't it?
Mike Hopkin: It's quite similar. But, I guess, perhaps an even advantage is if you're the team to score first, it really does seem to give you a greater probability of scoring subsequent goals.
Chris Smith: A lot of people also say that footballers are actually geniuses, but not just with their feet too.
Mike Hopkin: Yes, I mean, people talk about the idea of yards in the head and how footballers have good spacial awareness, when absolutely top quality footballers were tested for analysing the flight of balls and things like that, they were actually shown to be much more adept and researchers name players such as Zinedine Zidane, the French maestro and also André Shevchenko who has just signed for Chelsea, as some of the most intelligent players in football.
Chris Smith: Although having said that, they're not so good at spotting the trajectory of curve balls are they?
Mike Hopkin: Well, this is an issue, especially for goalkeepers in this year's World Cup. The new ball which features a different array of panelling to traditional balls has just been unveiled and some goalkeepers are worried that it bears too much similarity to baseballs. There's a baseball pitch called the 'knuckle ball' which is notoriously difficult to read and a skilled pitcher can get a batter out in baseball by throwing this ball that curves in very unpredictable ways. The new ball seems to spin and twist more in the air, which could cause some upsets at the world cup.
Chris Smith: But why have they changed it at all?
Mike Hopkin: Well, a lot of it is the idea of marketing new footballs I guess, but the manufacturers claim that it allows the ball to be rounder, by reducing the number of points where the panels are joined. They say that their new ball has only 14 panels as opposed to the 32 of a previous football. So they're arguing that there are fewer pointy bits on the ball, which makes it rounder, as long as you remember to pump it up correctly.
Chris Smith: Are you going to have a flutter on this year's outcomes?
Mike Hopkin: Well, I think I may do. Obviously I'm biased towards England. It looks like the bookmakers are going to take more than a billion pounds just in the UK alone in bets. The only problem is that people tend to rely on hunches a lot, when they're betting, that's not always a good strategy. Even tipsters who write for newspapers, in a recent study, were shown only to get things right about 42% of the time. And that might sound quite good except that in a recent analysis of English League games, if you just bet on a home win for whoever is playing at home at the time, your success rate would have been 47%, so economists have been trying to design a better model that predicts, more accurately, which team is going to win and, hopefully, make you a bit more money.
Chris Smith: Have they been successful?
Mike Hopkin: One economist who designed a model that he tested in the year 2000 bet a pound on each of 20 games and ended up, up by 50, which his okay but not great. The other thing to remember is that bookmakers, because they're running a business and have to make money, always skew the odds in their favour so, in the long run, it's pretty hard to beat them.
Chris Smith: Now, lastly Mike, the magazine Marie Claire have done a study recently and they looked at a number of World Cup international players, many of whom said they were going to steer clear of any sex because they thought it might affect their game. No sex before marriage is one thing, but no sex before football, is there any scientific basis for that?
Mike Hopkin: This is a bit of received wisdom from football coaches that seems to stretch back to, at least, the 1970s, if not further than that. There's actually a catch phrase that says "nothing after Wednesday if you're playing on Saturday".
Chris Smith: So are they worried about players rolling over and falling asleep on the pitch or something?
Mike Hopkin: Well, there is the idea of guys doing that immediately after sex, but it seems quite strange to imagine that that might persist into the next day. There have been some physiological studies to try and get to the bottom of this problem and there's no drop in oxygen utilisation or endurance, strength. One study showed that having sex raises a man's heart rate and blood pressure no more than a particularly stressful day in the office.
Chris Smith: Obviously, they don't have a very interesting partner.
Mike Hopkin: Well, we couldn't comment on the footballers wives, I think it is fair to say that it won't be too much of an issue for many of the players because they are all living in training camps but a lot of the coaches have incentive based schemes were the families are allowed to visit the players if they'll get to the quarter finals. I don't know whether they just think the earlier matches are more important and they can let the players rely on momentum, perhaps the winning momentum of scoring a goal, but it seems that there is really no basis to the idea, which will probably be a relief for lots of footballers.
Chris Smith: Nature's Mike Hopkin, lacing up his scientific boots in readiness for the World Cup.This is the 15th June edition of Nature's podcast with me, Chris Smith. Coming up, we'll be homing in on the brains exploration centre and reflecting on a new form of glass that's made from carbon dioxide. First though, here's Jesús Mavárez from the Smithsonian Tropical Research Institute in Panama. With the help of a local butterfly called Heliconius heurippa, he's shown that new animal species can arise, not just by splitting off from a parent, but through the formation of hybrids. He's been able to reproduce Heliconius heurippa in the laboratory by crossing two different butterflies, Heliconius cydno and Heliconius melpomene. Nature 441, 868–871 (15 June 2006)
Jesús Mavárez: We have found that the butterfly species in the genus Heliconius is actually a hybrid between two other, closely related, species. So we have found that Heliconius heurripa is, indeed, a hybrid between Heliconius cydno and Heliconius melpomene.
Chris Smith: And I guess this suggests, then, that animals as well as plants can speciate, give rise to new species, by creating hybrids which people previously thought wasn't the case?
Jesús Mavárez: Yes, most people think that this kind of speciation in animals is very, very rare or even absent. So we have found a very convincing case using ecological, morphological, genetic evidence, that we do have a hybrid animal species.
Chris Smith: How did you do it?
Jesús Mavárez: The first thing we did was to show that genetically Heliconius heurippa shows a mixing of genes that are present in either Heliconius cydno and Heliconius melpomene. And then in the lab we have recreated the colour patterning of Heliconius heurippa by making specific crosses between Heliconius cydno and Heliconius melpomene. In these, in just three generations, you can create in the laboratory, synthetic hybrids that are morphologically identical to Heliconius heurripa and they resemble each other so close that you can mate the white Heliconius heurripa with the synthetic heurripa looking hybrids.
Chris Smith: Can the new hybrid actually mate with either parent though, or is it a genuine new species and it's not cross-fertile with either of its parents?
Jesús Mavárez: Yes, Heliconius heurripa is perfectly cross-fertile with Heliconius cydno and there is evidence of hybrid sterility when you cross Heliconius heurripa, so the hybrid, with the other parent, Heliconius melpomene. But we have shown that what is creating reproductive isolation between Heliconius heurripa and either parents is the strong assortative mating. Lets put it like this. Heliconius heurripa individuals are extremely choosy and they have a yellow and red colour pattern, so they have yellow and red colours in their wings. Heliconius cydno is yellow and Heliconius melpomene is red and what we have found is Heliconius heurripa only mates with individuals who have both the yellow and the red in the four wings.
Chris Smith: Where do you want to go with this next and do you think there are other species, other than just butterflies, lurking out there, that are probably up to the same trick?
Jesús Mavárez: Yes, when you look at the literature about hybrid speciation in animals all purposive cases occur in very well studied organisms like Heliconius butterflies, short-tailed fishes and cichlid fishes in Africa and there is no reason for that. The only explanation for this is that these groups have been studied in much more detail and that's why we have found the hybrids. So I guess that hybridisation or even hybrid speciation is going on in nature, it's just that it's gone undetected.
Chris Smith: A tale of two butterflies, Jesús Mavárez from the Smithsonian Tropical Research Institute in Panama with the first animal evidence for hybrid speciation. And now to your inner gambler. Nathaniel Daw from University College London has been looking at how the brain balances the desire to reap short term rewards, using information already to hand, with the desire to explore and discover new approaches which might be much more richly rewarded in future. He brain scanned subjects as they were offered a selection of slot machines in which to gamble. Nature 441, 876–879 (15 June 2006) ; Nature 441, 822–823 (15 June 2006)
Nathaniel Daw: We wanted to study how people make decisions in order to balance two competing impulses. The one is to gather up resources, such a money or food or water, and the other is to gather information in order to make better decisions in the future to gather up food or money or water. And we used a combination of brain scanning and behaviour and people making choices between slot machines to study this function. What we found was that you face a dilemma in a situation like this, you've seen a couple of slot machines and one of them seems better than other but they're somewhat random so you're not sure whether the one that seems to have paid off the best in the past will pay off the best in the future and so you face a dilemma...
Chris Smith: Do I stick with the devil I do know, or do I go for the devil I don't?
Nathaniel Daw: That's right.
Chris Smith: How did you do it, though?
Nathaniel Daw: We had a number of people who were asked to choose between a number of different slot machines in a brain scanner repeatedly and the slot machines paid off different amounts of money with some randomness at each choice. And we were interested in studying how they directed their choices, both towards things that seemed to be the best but also, particularly, how they explored or tried to gain information about slot machines that they didn't have as much experience with, in order to see if, in fact, they're better, to study the devil they don't know, as it were.
Chris Smith: Which regions of the brain were pressed into action when they were doing this task?
Nathaniel Daw: Well, in particular, during the times when they seemed to be exploring slot machines that seemed likely not the best, that they seemed to be checking out things, a part of the brain, that was the frontal polar cortex, just behind the forehead, a very high-level control area was differentially active. And an interpretation will be that this is probably because this is maybe the neuro-correlate of a function of overriding the drive to go for the thing that seems to be the best. In order to, sort of, take your medicine and go for the thing that might, in the long term, turn out to be better.
Chris Smith: So what's the significance of seeing that, wouldn't you have expected that anyway?
Nathaniel Daw: No, to the contrary actually, I expected something completely different. It could have been the case that people will systematically, explore things that they didn't know as much about preferentially and this stuff would be integrated in the brain. As it turned out I was completely wrong about that. We didn't find behavioural evidence that they were exploring in any systematic way and what we found instead is a neural separation between parts of the brain that were involved in exploration and parts of the brain that were involved in exploitation.
Chris Smith: Nathaniel Daw from University College London. Now meet the University of Florence's Mario Santoro, who together with his colleague Frederico Gorelli has discovered a new form of carbon dioxide which they've called 'a-carbonia'. It's like glass, which you'd expect because carbon is in the same group of the periodic table as silicone, which forms the basis of the glass we use today. Now although a-carbonia isn't stable at room temperature and pressure, it can be combined with silicone which might produce the strongest glass ever seen. Nature 441, 857–860 (15 June 2006) ; Nature 441, 823 (15 June 2006)
Mario Santoro: We discovered a material that we call a-carbonia. A-carbonia is analogous to silica, remember that silica is the most common glassy material, so a-carbonia is like the same as silica but instead of silicone you have carbon, so it was obtained by just squeezing carbon dioxide, which is a common gas, to very high pressure and typical pressure that we can encounter in the Earth mantle.
Chris Smith: And do you have to keep the conditions at those very high pressures, in order to keep it in that state, or is it stable?
Mario Santoro: No, at room temperature it is not stable anymore. The minimum pressure required is something around half a megabar, which is half a million of atmospheres. Then you start to produce this material, then you can lower the pressure down to a hundred dozen atmospheres and then it is still stable, then it becomes carbon dioxide gasses again.
Chris Smith: So, what's actually going on at the molecular level, when it forms this a-carbonia compound?
Mario Santoro: Carbon dioxide is a molecular where you have one carbon which is bound to two oxygens. When you squeeze this then you start to coordinate carbon to four oxygen atoms instead of two. And each oxygen makes a bridge between two nearest neighbour carbon atoms, so you have a network. It's an open network, it's not a molecule any longer.
Chris Smith: And how does this stuff behave chemically, is it pretty similar to glass, given that both carbon and silica are both in group four of the periodic table?
Mario Santoro: Yes, that's very similar to silica so this material completes our view on the group four elements of the periodic table because til now we didn't know the possibility of forming a glasslike material for carbon, which is a kind of exception, with respect to silicone and what we have below, germanium, even tin, so now our view is complete in this periodic line.
Chris Smith: Can you think of any possible applications for it, apart from its chemical interest, are there any reasons why you're interested in this from an industrial or an economic point of view?
Mario Santoro: This material that we discovered is the hardest glass known and we've seen that it is possible to combine CO2 with the silica to make a compound of the two, which probably makes this material much more stable at room conditions. In principle we could produce one of the hardest emulsions material know to now.
Chris Smith: University of Florence's Mario Santoro reflecting on the glassy properties of a-carbonia, a new form of carbon dioxide. So that's it for this week, thanks for listening. If you'd like to catch up with any of our previous podcasts, or read the text transcript that accompanies this programme, they can all be round at http://www.nature.com/podcast. Next time we shall be hearing about exciting findings from the middle ear and also why seismology in California looks set for a shake up. In the meantime, if you've still got an appetite for some more science, in this week's edition of the Naked Scientists podcast we'll be looking at the science of virus's, bacteria and fungi and also considering the colourful chemistry of red cabbage. That's the Naked Scientist podcast which is freely available from http://www.thenakedscientists.com. The Naked Podcast is produced at Cambridge University's Department of Pathology by Derek Thorne and Anna Lacey, and I'm Chris Smith.AdvertisementThe Nature podcast is sponsored by Bio-Rad, at the centre of scientific discovery for over 50 years and on the Web at http://www.discover.bio-rad.com.
