Nature Podcast

This is a transcript of the 7th August 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 podcast@nature.com.

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Kerri Smith: Coming up this week:(X-files theme music)

Chris Carter: For me it was all about the Science and I actually even resisted the science fiction label because I thought it took place in the world of speculative science.

Kerri Smith: We talk to the creator of the X-files about science and the supernatural. And our competition winner's choice of PODium speaker is Michael Shermer.

Michael Shermer: We cannot go on depending indefinitely on fossil fuels, we need new technologies, but without new politics and economics, we cannot make the transition to a type 1 civilization.

Kerri Smith: All that and more on this week's Nature Podcast, I'm Kerri Smith.

Adam Rutherford: And I'm Adam Rutherford.

Adam Rutherford: When it comes to design, evolution has the advantage of millions of iterative steps over billions of years, so why not copy biological structures to get the best out of your product. That's what a team at the University of Illinois in Urbana Champaign has done by making a new eye-like camera. All digital cameras currently have detector arrays on flat planar surfaces, whereas all eyes in the natural world have their retinas on a curved surface. I called up lead author John Rogers and asked him about the advantages of a curved retina over a flat one. Nature 454, 748–753 (7 August 2008)

John A. Rogers: Well it turns out that the optics of imaging essentially don't like flat surfaces and so in order to get an image to reproduce accurately on the planar surface of a conventional CCD requires multiple imaging objects, multi-component lens system. So if you look at a sophisticated camera or a video camera, it involves, you know, quite a substantial amount of glass in multi-component optics and so one can do quite well with that kind of set up, but there is a cost and a weight associated with those imaging objects that are not present in biological systems, because biology uses curved surface imaging detectors rather than planar ones.

Adam Rutherford: So you've turned to the human eyes as a model. What are the specific advantages of having a curved surface rather than a flat one?

John A. Rogers: Well it's really just much easier to get a high-optical performance, good imaging characteristics, when you have your detector on a spherical surface rather than a planar one and it has to do with the way that spherical wave fronts that are emerging from objects in the world are imaged on to the detector surface. So with the very simple single component lens, you can form very nice images on a hemispherical surface, but not so nice on a planar one.

Adam Rutherford: How have you actually managed to create this curved surface and how have you managed to get the detectors on them.

John A. Rogers: Well, two things, so if you think about that being your technical goal, you have two options. One is, you can re-invent all of semiconductor processing which is now well developed for planar surface to be directly applied to hemispherical surface and that turns out to be an incredibly daunting engineering challenge. The other approach to that same endpoint that you can pursue, which we pursued, is to figure out how to take the planar CCD camera are formed, in the usual way on a semiconductor wave front and reshape, do a geometry transformation from that 2D planar layout to a hemispherical shape. And in order to accomplish that, we did two things. One is that we figured out how to make the CCD extremely thin and designed into a kind of interconnected mesh that involves small eye lens connected by very fine and thin wires. And in that mesh it turns out that you can squeeze the system such that it allows you to go from that planar layout to a hemispherical layout and then the other innovation that we introduced here is a means for actually accomplishing that transformation. It involves an elastomeric element that basically reshapes the planar layout into the desired hemispherical shape.

Adam Rutherford: And here's the question that everyone kind to ask, when are we going to see this in the shops? When is there going to be a practical application for your new curved surface?

John A. Rogers: Well, first of all to say that that's our end goal. You know, it's great to have a paper published in Nature and that's a fantastic thing but we measure success by commercial penetration, I mean, the sort of the approach that we are having, so how would we see it coming about it. I make a couple of comments, one is that we think an advantage of this approach is that it uses conventional established electronic technology and so this curving process and the formation of this hemispherical system is kind of a back-end packaging technology that is additive on top of already well developed CCD technology. We are not reinventing the CCD or reinventing ways to shape it into a final form, that's a result I think that puts it closer to commercial reality than we would otherwise be. So if I have to put a time limit on it and it would probably be 3 to 5 years out, the way we see it happening is penetration first into advanced imaging systems and cameras that might be suitable for industrial or military use, but the technology itself we see potentially penetrating all the way down into consumer projects systems if everything goes well.

Adam Rutherford: John Rogers from the University of Illinois, Urbana Champaign.

Kerri Smith: Coming up shortly viruses that make other viruses sick. But first, earlier this year, we ran a competition to identify three sounds of science and win an Ipod. The tie-breaker was to suggest a speaker for our opinion slot, the PODium and after sifting through hundreds of entries, we've picked a winner. We thought it best let the winner introduce the PODium himself.

Ramin Samadani: I'm Ramin Samadani in Menlo Park California and this is the Nature Podcast. My winning recommendation for the PODium is Michael Shermer, publisher of the sceptic magazine and professor at Vermont Graduate University. Here he is on the future of social evolution of humanity.

Michael Shermer: We cannot go on depending indefinitely on fossil fuels. We need new technologies, but without new politics and economics, we cannot make the transition to a type 1 civilization. Let me explain, in a 1964 article, the soviet astronomer Nikolai Kardashev described 3 types of civilization. Type 1, can harness all of the energy of its home planet. Type 2 can harvest all of the power of its sun and type 3 can master the energy from its entire galaxy. In 1973, the astronomer Carl Sagan estimated that we are a type 0.7 civilization. Current estimates put us at around 0.72. The Kardashevian scale is logarithmic. Each increase in power consumption requires a huge leap in production. In other words, we have our ways to go to make the transition. Fossil fuels won't get us there. Renewable sources such as solar, wind, and geothermal are a good start. Nuclear power, especially fusion could get us there once the technologies are developed, but the problem is not just technological. We have a track record of remarkable technological solutions to survival problems as long as political will and economic opportunities allow. We need a type 1 polity and economy along with the technology to become a type 1 civilization. We're close. Consider how far we've come in the long history of our species from type 0. Type 0.1 groups of hominids living in Africa with the dominance hierarchy within groups and much violence between groups. Type 0.2: bands of roaming hunter gatherers with a mostly horizontal political system and an egalitarian economy; Type 0.3: tribes of individuals with a settled and agrarian lifestyle plus the beginnings of a political hierarchy in a primitive economic division of labour. Type 0.4, chiefdoms with the beginnings of a significant economic inequalities and a division of labour, lower class members produce food and other products, consumed by non producing upper class members. Type 0.5, states with a political jurisdiction of a well defined geographical territory and with a mercantile economy that seeks a favourable balance of trade in a win-lose game against other states. Type 0.6: empires that extend their control over peoples who are not culturally, ethnically, or geographically related with a goal of economic dominance over other empires. Type 0.7, democracies, that divide the sources of power over several institutions run by elected officials voted for by some citizens with a beginnings of a market economy. Type 0.8, liberal democracies that give the vote to all citizens and with market set to embrace free trade with other states. Type 0.9, democratic capitalism: now spreading across the globe to democratic movements and free trade agreements. Finally type 1.0 Globalism: that includes worldwide wireless internet access, all knowledge digitized and available to everyone, anywhere, anytime; a global economy with complete open economic borders and free markets where anyone can trade with anyone else without interference from states or governments. And where all states are democracies in which everyone on the planet has to franchise. The forces that work that could prevent us from becoming a type 1 civilization are primarily political and economic. The resistance by non-democratic states to turning power over to the people is considerable. Especially in theocracies, whose leaders would prefer we all revert to type 0.4 chiefdom status. The opposition toward a global economy is substantial. Even in the industrial West, where economic tribalism still dominates the thinking of most people. Hopefully, in the evolutionist's deep time and the historian's long view the trend lines toward achieving type 1 status tick inexorably upward; that is change we can believe in.

Kerri Smith: Michael Shermer on the PODium as introduced by competition winner Ramin Samadani and remember if you've got any of your own suggestions or any other feedback, e-mail us at podcast@nature.com.

Jingle

(X-files theme music)

Adam Rutherford: From a well known sceptic to quite the opposites. Yes, that iconic music signals that the X-files have been reopened. A brand new movie version of the supernatural investigations of FBI agents Mulder and Scully is now in cinemas. As ever Scully the scientist is the definitive cynic but Mulder is on the side of the unworldly. In an exclusive interview I spoke to Chris Carter, creator of the TV series and Director of the new film, 'X-Files: I Want To Believe'. I started by asking him, how long we've been missing Mulder and Scully.

Chris Carter: Yes, you've been missing them for 6 years if you were a fan of the TV show and 10 years if you saw the last movie. I can tell u that it is a suspense thriller. It is a story that stands on its own. It is in keeping, what we think, is the scariest part of the X-files which takes place within the realm of extreme possibility.

Adam Rutherford: Now let's talk a little bit about the science. I always saw that science really is one of the key aspects to the X-files, as Scully is rational to the core. Now bearing in mind the aliens, the crypto zoology and the monsters, how important to you, as its creator is it to get the science right?

Chris Carter: For me, it was all about the science and I actually even resisted the science fiction label because I thought it took place in what I would call the world of speculative science and I think that Steven Spielberg has said that about Close Encounters, which, I always like that. The idea that it's just over the horizon, it is on the frontiers of science and actually it is funny that when we are writing about cloning back in the first season of X-files which is 16 years ago, that was science fiction to some extent. Then a sheep named Dolly came along.

Adam Rutherford: Yeah, that was published in Nature in 1997, so you got the frontline on that. So how much do you allow scientific verisimilitude to get in the way of plot?

Chris Carter: It is important to us. We were actually always very rigorous on our science, because it really represented Scully's point of view. It was the centre of the show. Scully, actually she represented us and Mulder represented I would call it the radical portion of the show. He was always pushing the limits of knowledge, belief, and understanding and Mulder always won, that is something that I guess would be a blow to science and scientists, but it made the show more interesting.

Adam Rutherford: I understand that. I can remember an episode in which Scully performs a Southern Blot, which is a type of DNA analysis, I used to do that all the time. She was looking for a fifth nucleotide from alien DNA. She was much, much better at it than I was and did it in one day. Do you ever get complaints? Do you ever get scientists saying, you know, this is too far form the reality?

Chris Carter: No, you know it is, I think that scientists like the show by and large and we, I remember that particular episode that you are talking about and I had very specific instruction on that episode from a virologist Dr. Anne Simon who became, I would call it our, sort of, official and unofficial scientific advisor. We dealt a lot with DNA, with genetics, with viruses and you know the whole idea of nucleotides, really, sort of, came as a result of my conversation with her.

Adam Rutherford: I remember her saying at that time that working with X-files is more interesting than working as a virologist. Just a couple of quick questions to end with: Who is your favourite monster of the week?

Chris Carter: Home is one of my favourite episodes and it's I think the beloved for the mother, we sort of pulled him under the bed and it involves mutant brothers who keep their mother, their freakish mother under the bed.

Adam Rutherford: Okay, is there going to be third movie?

Chris Carter: It would depend on the success of the second movie and I'm knocking wood right now that the second movie finds an audience.

Adam Rutherford: Quick question, Will Mulder and Scully ever get it on?

Chris Carter: Do they hook up? that's been the question of the hour or of the, for me, about the last 6 weeks. Let me say to you that if you go to see the new movie, you'll see Mulder and Scully certainly looking at their relationship and involvement in a way that I think anyone would after 16 years together.

(Clip from the Movie)

Scully: Mulder...
Mulder: What is that animal tranquilizer doing in the tissue sample of a man's severed arm?
Scully: I can't even begin to speculate.
Mulder: you said you heard barking dogs,

(Water flowing from a tap)

Scully: whoop...
Mulder: Not a germ.
Scully: Mulder, what are you doing?
Mulder: Is it a tranquilizer that you might give the dog?
Scully: Is it funny Mulder, you pose the so called visions out of thin air and now has got used trying to connect them.
Mulder: When I see a man cry tears of blood at a crime scene, he recognizes without ever having visited. I need to go on the limb, you know, what I'm saying?
Scully: There's some blood?

Kerri Smith: Agent Scully as ever doing her very best to stick to the rational and before her Chris Carter whose new film the X-files: I Want To Believe is on general release right now. There is an extended version of that interview on the Nature Podcast Extra in iTunes or on our web site and be warned it gets seriously geeky.

Adam Rutherford: Now it might sound a bit like an X-files plot line but a mimivirus has been found that can infect other viruses. This report is from Charlotte Stoddart.

Charlotte Stoddart: Many human diseases are caused by viruses that hijack our cells, turning them into virus-making factories. Now researchers have discovered that viruses too can get sick. A team at the Université de la Méditerraneé in France have found, for the first time, a tiny virus that has infected another larger virus. They have nicknamed the tiny parasitic virus Sputnik. The unfortunate host, named mama, is a new strain of a giant mimivirus and the finding could explain how viruses are able to swap genes, making them even more potent. I called Bernard La Scola to find out more. Nature advance online publication (6 August 2008)

Bernard La Scola: In this paper, we have isolated a new giant virus which is called the Mamavirus that is very close to mimivirus and what is curious with this virus, when we isolated this virus we found a small virus that infect these big virus, so it's really original.

Charlotte Stoddart: And is this the first time that anyone has found a virus within another virus.

Bernard La Scola: Yes, the first time and a mimivirus developing in the virus factory and the small virus infect this virus factory and that leads to abnormal forms of the mimivirus. So it's pathogenic for the virus.

Charlotte Stoddart: This small virus then it makes the larger virus that it infects, it makes it sick.

Bernard La Scola: When the big virus mimivirus or mamavirus are infected by Sputnik there is thickening of the membrane and sometimes the particle do not close or we can't find the mimivirus particle that are empty, but in which we find some Sputnik particle and when we count the number of mimivirus particle, it is very low compared with Sputnik, only with mimivirus virus.

Charlotte Stoddart: So this tiny virus that you've named Sputnik, then it sort of prevents the giant virus, the mimivirus from replicating properly.

Bernard La Scola: Yes.

Charlotte Stoddart: Do you think that Sputnik is a member of a new class of viruses which you've named virophages? Where does this name come from?

Bernard La Scola: There is a class of virus called phage and phage usually eats virus that infect bacteria and whereas that act like phage, but instead of infected bacteria it infects the virus factory.

Charlotte Stoddart: And now you've found one example, are you expecting to find more, how common do you think this is?

Bernard La Scola: We think that this is probably very common, because this small virus when we studied its genome, gene contents, we find genes from other viruses. So we think that this kind of virus do exchange gene between viruses, but to do that they need to infect other viruses, so we think that this is probably common.

Charlotte Stoddart: And this is the other really interesting part of this finding, but as you say this tiny virus could be a vehicle for gene transfer between larger viruses, how exactly would this work?

Bernard La Scola: We know that from phages that there are genes that allow integration of the DNA of the virus in the DNA of the bacterium and so we find this kind of homologous in the tiny virus. So we think that it is the same phenomenon that is used to infect within other host and probably other big viruses.

Charlotte Stoddart: And could this gene transfer by this tiny virophage explain perhaps how resistance spreads between viruses?

Bernard La Scola: Too early to say that now, it's probably important for further evolution of viruses and exchange between viruses of different kingdoms. You know, actually in the live, there are 3 kingdoms and each kingdom has its own viruses that are evolved with all member of each domain and this tiny virus seems to allow exchange of genes between the viruses of the different domain of life and that is really original.

Kerri Smith: Bernard La Scola there, talking to Charlotte.

Adam Rutherford: Finally this week Geoff Brumfiel discovers that the Earth's insides are a bit wonky.

Geoff Brumfiel: The innermost part of Earth's core has a little bit of a paunch. The eastern side of the core, that's the bit under Asia, appears to be bigger than the west. It is not something that us surface dwellers think about a lot, except for those of us who happen to be geophysicists like Julien Aubert at the Institute of Geophysics in Paris. He and his colleagues have spent a lot of time recently thinking about why the inner core is lopsided. They've got a pretty good theory about it and I called him to learn more, starting with what the core looks like. Nature 454, 758–761 (7 August 2008)

Julien Aubert: We have two layers in the Earth's core. So we have the outer core which is fully liquid; it is liquid like water and at the deepest depth of the Earth you have the solid inner core. So why it is solid and it is solid not because it is cold, it is because the pressure is very high and so the pressure is so high that even that the temperatures of the centre of the Earth which are of the order of 6000 Kelvin, iron becomes solid.

Geoff Brumfiel: So I understand that that inner core, that solid core of iron has been something of a puzzle for you guys, because you would expect it, I guess, naively just to be symmetric, but it is not. The eastern hemisphere behaves differently than the western hemisphere.

Julien Aubert: Yeah exactly, so the eastern hemisphere, let's call it the Asian hemisphere, because it is roughly below Asia. There seismic waves are generally a little bit faster. They are less anisotropic and they are also more attenuating that this they can travel less before vanishing, than in the western hemisphere which has the opposite properties and this when you think about it is really difficult to explain based only on physical properties of matter alone because we don't see the reason why the given hemisphere should acquire different properties as the other hemisphere.

Geoff Brumfiel: So you guys have developed a model which helps explain why the core has this sort of lopsided property to it?

Julien Aubert: So the idea behind our model was that if you want to explain such a pattern that exists on the inner core, knowing that the general physics of the outer core is very homogenous that it is the same properties everywhere, you have to invoke some kind of effect that comes from elsewhere and since the core dynamics are controlled by the mantle, a very easy candidate is the lower mantle of the Earth which is rocky and sturdy but still it is very heterogeneous as well, due to the plates. These plates go down at places and where those plates touch the core mantle boundary, they impose a kind of colder spots. So this is really the contents of the numerical model that we've been building. It is a model of outer core dynamics under the influence of a thermally heterogeneous mantle.

Geoff Brumfiel: So what you're basically saying is that there are these cool spots on the mantle that are affecting the outer core, but then how does that get communicated to the inner core. How does that change the inner core?

Julien Aubert: So this was really the output of the model. So those cold spots on the core mantle boundary which stay there for one hundred million years to three hundred million years may be and they generate very long term flows in the outer core, which we call thermal winds and these winds basically stay there for a very long time and that is enough to influence the growth process of the inner core. So what we found in the model is that when these winds touch the inner core and they do so at very specific positions which is actually in the eastern hemisphere of the inner core, they induce growth rate anomaly that is the inner core grows faster in this region, because they are touched by something colder and in this case, the pattern that the model gave us was actually very similar to the pattern of seismic heterogeneity of the inner core which was observed by the seismologists.

Geoff Brumfiel: That's really interesting. I mean, does it answer our needs to the sort of, larger questions about how the Earth behaves as a planet.

Julien Aubert: This question was an important one for geophysicists, because we liked to understand the Earth as a system of layers, so the inner core, the outer core, the mantle, the crust and we like to understand it as a system of dynamically coupled layers. So this model was challenged by these observations, so this is the reason why many people having been aiming at answering this question and I am sure this is not going to be the only paper on this question. There are probably a few more to come. So what it tells us about the Earth as a planet is that it's really an evolving system and the dynamics of it helps to understand a lot of things. The present dynamics helps a lot to understand the best.

Adam Rutherford: Julien Aubert and sure enough we will be revisiting the Earth's core next week as well as assessing the damage that hidden infectious diseases can cause and finding out what the future of transport will be. But for now(X-files theme music)

Adam Rutherford: I'm Fox Mulder

Kerri Smith: And I am Danna Scully, the truth is out there.

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