Nature Podcast

This is a transcript of the 13th September 2012 edition of the weekly Nature Podcast. Audio files for the current show and archive episodes can be accessed from the Nature Podcast index page (, which also contains details on how to subscribe to the Nature Podcast for FREE, and has troubleshooting top-tips. Send us your feedback to

Geoff Brumfiel: This week, can this man forecast your future?

Daniel Lacuna: So my research is about predicting the success of scientists.

Kerri Smith: And the long struggle to make a HIV vaccine.

Morgane Rolland: After over 25 years of really modest success we still did not know what can mediate protection.

Geoff Brumfiel: Plus the Pentagon's longstanding microwave weapons program. This is the Nature Podcast. I'm Geoff Brumfiel.

Kerri Smith: And I'm Kerri Smith.


Kerri Smith: Almost as soon as HIV was discovered people started thinking about making a vaccine against it. The past few years have seen several clinical trials. One of the most promising took place in Thailand and involved 16 thousand participants. It was a modest success. The vaccine worked in 30% of recipients. Since then scientists have been trying to figure out why that particular vaccine worked albeit only a third of the time. This week a team led by the US military HIV research program who part-funded the original trial report their findings. They highlight one susceptible spot on HIV's shell or envelope that future vaccines could aim for. I spoke to team member Morgane Rolland. Nature (2012)

Morgane Rolland: The idea to block HIV acquisition would be that we would add vaccines that would elicit antibodies that would recognize the envelope of the virus, so the envelope is what coats the viral particles and what is recognized by its immune systems, but it's also the most viable region of the HIV1 genome. It evolves at a rate of about 1% per year in an infected individual, so we would want to design antibodies to try to target this envelope.

Kerri Smith: You've really got a shape shifting enemy on your hands here. Talk me through the Thai trial, that's the trial that the results in this paper have come from. The results of the trial were actually announced a couple of years ago, weren't they?

Morgane Rolland: Yes, the results were announced in October 2009. There was a first trial showing some efficacy. It was a modest result, but we found that there was 31% efficacy, so it was really the first opportunity for HIV researchers to try to see what was associated with the protection that was conferred.

Kerri Smith: So, let me just clarify if I've got this right. So, previously people have looked at the results of the trial and they've tried to compare people who got the vaccine with controls and look at various immune characteristics that correlate with whether they were infected or not.

Morgane Rolland: Yes.

Kerri Smith: But that's not the same as saying that these immune characteristics are causing the infection I suppose, so what did you do here instead?

Morgane Rolland: What we're doing is that we take all the infections that were rebutted in this trial and we get samples, we get plasma samples from the time point when people were diagnosed with HIV infection and we sequenced those viruses and then we want to compare the sequences that we obtained from vaccine recipients to the sequences that we obtained from placebo recipients. And the idea here is that because it's a randomized trial, we can assign any difference that we will see in the sequences to the vaccine status, to the fact that they had to receive the vaccine. And the idea is that the vaccine did selectively block certain viruses and we want to try if we can define those viruses or characterize those viruses to see if we can distinguish them by their sequences.

Kerri Smith: And you were able to find genetic differences in the viruses.

Morgane Rolland: Yes, that was actually quite unexpected, but indeed we did see differences at two positions in the V2 region and we found that the vaccine efficacy was increased to 80% for viruses that carried these two specific signatures.

Kerri Smith: So, knowing about these bits of the viral proteins, these sections of the envelope and the fact that the vaccine could only target those bits for effective protection, does that help people to design better vaccines in the future?

Morgane Rolland: I think yeah because, I mean, this study, it's an independent confirmation that this specific region V2 would be potentially good target for HIV vaccine. We still, you know, after over 20 years or 25 years of really modest success in HIV vaccine design we still did not know what could help, what could mediate protection. We have a very unclear understanding of what are the correlates of protection. These studies do confirm that V2 would be a potential target for HIV Vaccines.

Kerri Smith: So, on a clinical level then and if we could monitor the type of HIV and its particular type of envelope in a particular area then you could administer the right vaccine to those people.

Morgane Rolland: We can envision that in the future, you would check, so viruses that are circulating in the population in the area where you want to test your vaccine to see if your vaccine would be the right match for this population because we know that there's such a lot of diversity in HIV-1 viruses and we are clearly very, very far from an HIV vaccine that would be universal. So, research at the moment is more focused toward vaccines that would work in a specific geographic location of organs to specific subtype.

Kerri Smith: Morgane Rolland there. Coming up an equation to predict scientist's future success, but before that here are the research highlights with Charlotte Stoddart.


Charlotte Stoddart: Many ocean dwellers rely on diving deep to get dinner. Take the southern elephant seal, females forage down as far as 1500 meters, where no natural light can penetrate. So how do they see their snacks? It turns out they look out for the bioluminescence of their prey. A French team of scientists used satellite tracking and a light sensor to monitor four seals as they foraged. The seals did a lot more hunting when there was a greater level of bioluminescence from critters such as lantern fish. Other sea creatures might use the same technique, the team says. The paper is published in PLoS One. Nature 489, 180 (13 September 2012)When people get too hot, they sweat and now researchers have found a way to cool buildings in the same way. A team based in Switzerland produced a heat sensitive gel that releases water when heated. The water takes heat away with it. So when the team coated miniature model houses with the gel and then exposed them to simulated tropical midday sun, they were up to 20 degrees Celsius cooler than un-gelled model houses. A brief period of pretend rain recharged the gels. Find that paper in the Journal Advanced Materials. Nature 489, 180 (13 September 2012)

Geoff Brumfiel: In 1962, the US government detonated a nuclear weapon high above the earth. The blast created an electromagnetic pulse that knocked out lights and phones in Hawaii. It also awakened defence scientists to a new possible weapon. If could be developed, a microwave beam could knock out enemy electronics from afar. Decades later, the dream of microwave weapons lives on. Not that type of microwave weapon Kerri. Nature 489, 198–200 (13 September 2012)

Kerri Smith: Oh, sorry.

Geoff Brumfiel: Sharon Weinberger, defence journalist and visiting fellow at the Woodrow Wilson International Center for Scholars writes about the state of microwave weapons research in this week's issue of Nature. She joins me on the line from Washington. Sharon, what makes the possibility of microwave weapons so appealing?

Sharon Weinberger: The history of high power microwave weapons sort of dates back to 1962 to Starfish Prime, the high altitude nuclear test which took out, well it took out lights and disturbed phones over Hawaii and eventually after a number of months, it crippled some satellites and so it sort of awakened the scientific community to the effects of an electromagnetic pulse on electronic systems, which is basically it can fry the systems, it creates spikes in voltage that can take out, you know, modern electric systems.

Geoff Brumfiel: What I hadn't really realized until I read this article, is that the US military continues to be even though the cold war is well behind us, very interested in trying to create a focus sort of ray of electromagnetic radiation to fry electronics from afar right?

Sharon Weinberger: That's true, I think some of that is just a nurture from cold war spending, I mean we're still building fighter aircraft that were started during the cold war, but part of it is there is still this idea that other countries are investing in these areas, regardless of the fall of the Soviet Union, high power microwave weapons are for us, a type of weapon that could be useful even in today's conflict. You know rather than dropping a bomb on a command and control centre and perhaps having civilian deaths, you could take out, you know, the computer systems of a foreign military just with the zap of a weapon.

Geoff Brumfiel: Sounds sexy.

Sharon Weinberger: Well it is sexy, and that's what's kept it alive for so long with so much funding because you know, people give this great power point briefings, you know, it's sort of out of Star War, Star Trek, you know, zap this zap that, take it out, no damage. And the problem or the flip side of that is that people have been promising these weapons for many decades, but we still haven't seen one through to deployment, although there have been unconfirmed rumours of use in the field, but not claims that I consider to be credible.

Geoff Brumfiel: And so you've dug in here and found some of the problems with these weapons, some of the reasons they don't work very well. I mean, they can be as simple as a misty day.

Sharon Weinberger: Well, we looked to find between, there is different weapons have different configurations and can be used for different things. I for example went on a public press day on a test for what's called the Active Denial Weapon, which is a millimetre wave weapon that heats just the very, very very top layer of skin. It meant to be used against people of course, not against electronics. The problem is that it's a very, very difficult weapon to use in the field, it takes 16 hours to power up, the beam can be attenuated by moisture of the air, so on a rainy day, yeah it doesn't work very well. Rather than repelling people, it just kind of warms you up.

Geoff Brumfiel: I have to say though I've seen a video of you somewhere in the path of this beam, you did move pretty quickly once…

Sharon Weinberger: Yeah, you know, you feel something on you and you move away.

Geoff Brumfiel: So, why else don't these weapons work very well?

Sharon Weinberger: Number one is the size. The Active Denial System needs to be, it's been developed in two configurations. One is sort of on a flat bed truck and the second is on a Humvee. These are huge, huge systems, very, very complex. As I said, the Active Denial System takes 16 hours to essentially power up, it has a complex cooling system. When it's on, when it's shooting, you can't move the Humvee or the truck. So you have to ask yourself how useful is that on a modern battle field with you know IEDs with insurgence, what has always been a major challenge is developing something that's small enough and compact enough, yet powerful enough to be deployed.

Geoff Brumfiel: Another interesting thing I picked up from this article is that it's not always the case that this thing will work the same way every time. If you shine microwaves on a building, you're not going to get the same results, it's somewhat unreliable right?

Sharon Weinberger: This is part of the problem. You know, there's all the sort of literature out there, like you know the fearsome e-bomb will take out every computer in your house, but you can test those things in a lab, but it's very hard to test them sort of in a real world environment. There was a test in the late 1980s of an HPM system called Gypsy, which took out a bank of computers but here the scientists knew exactly where they were lined up, where they were, it's really something different in a real world environment, where you need to say, take out a commanding control centre. You don't know for instance exactly how many feet underground that is, how you know the bunker is set up, you're not necessarily sure it's going to take everything else that you need it to take out.

Geoff Brumfiel: Do you think that microwave weapons are going to go away?

Sharon Weinberger: Oh absolutely not. I'm not even necessarily sure that they should go away. You know the difference between high power microwaves and perhaps some of the fringier areas of weapons that I've looked at, is there's a lot of good science that can be done and really is being done in this area. There is a legitimate concern that this is a capability, it's a capability that other countries could develop and this could be said for being prepared for and not pretending that it doesn't exist. I think that the problem with this area has been people making extravagant outlandish claims about what can be done in an effort to have things funded, so I think they need to roll back and have a realistic assessment of what is actually useful and what should be funded.

Geoff Brumfiel: Sharon Weinberger there.

Kerri Smith: We've got Editor Mark Peplow on standby for the news in just a moment. First though, how big is your H index, don't be alarmed if a scientist asked you this question. Named after physicist, Jorge Hirsch, the H index is a way of gauging the performance of a scientist and it's based on the number of times their publications have been cited in other papers. It's used to help decide whether or not to hire someone or to give them tenure. The problem is that H index change over a scientist's career, often for the better and there's no simple way of predicting these gains. Now Daniel Acuna, a postdoc at Northwestern University near Chicago has come up with a way of predicting someone's future H index, which he describes in a commentary article in this week's Nature. Reporter Ewen Callaway talked with Acuna, who hopes that career advancement isn't just about size.

Daniel E. Acuna: Yeah, so my research is about predicting the success of scientists. Of course, success is very ambiguous, the H index is sort of wildly known and probably the most used index for measuring publication success. Unfortunately, the H index was never meant to measure the future and that's what our research is trying to do in this article.

Ewen Callaway: How do you break it down, and what are some of the factors you include in trying to predict how successful a scientist would be down the line?

Daniel E. Acuna: Yeah let me explain first, what we did you get at the conclusion from the factors that are important. We pull information from about 38,000 neuroscientists and other of life science people, from which is a crowd based web site, where scientists go and fill that information about affiliation, collaboration and advice. Then we match thousands of them to publication records and citation records etc., and we are able to reconstruct their history, how they look, for example, in 2005 and how would those correlate to the H index that this person had in 2010. So we found if the best equation that would predict the H index at different forecast times.

Ewen Callaway: So, how did your predictions do?

Daniel E. Acuna: Well, we found two things. First we found that using all the features that we use in our study, we are able to predict, almost twice as accurately as the H index alone, the future H index of someone. The second finding is that the features that are most important are directly related to the individual merit of the researcher. For example, the diversity of your publications is important. How popular and prestigious the journal is. So if you publish many, many papers, if you publish in many different journals and you try to publish in top journals and you're relatively young, then you have a very, very bright future in terms of your H index. So this equation is giving you a way of predicting the future and weighing each of these features.

Ewen Callaway: Is this a measure that universities should be using or should think about using when they decide whether or not to hire someone or whether or not to offer them tenure saying well here's a statistical measure of how well you might do in the future.

Daniel E. Acuna: Yeah, we believe that this is the best way of measuring the potential of someone to just have a committee of peers that understand the field very well, that understand the needs of the institutions etcetera. Our equation just serves one specific aspect of the potential of scientist that is the publication record. If committees are trying to get a good estimate of that then we believe the neuro scientists and other life science should use this equation to try to get a better estimate about the future of H index.

Ewen Callaway: I've got one final question for you. Have you ever tried using your equation to read the tea leaves of your own career?

Daniel E. Acuna: Yes unfortunately, yes, and I say unfortunately because my H index is very bad right now and my position is even worse. Now how I remedy that is to see that equation, it's explaining about 50% of the variants that we see in the data, so in a sense while it may not be predicting a very bright future for myself, I'm hoping that I will prove my equation wrong in that order, 50% that it is not able to explain in the next 10 years.

Kerri Smith: Daniel Acuna talking to Ewen Callaway. That comment article is available at

Geoff Brumfiel: And there's a lot more besides that at this week and Mark Peplow is here to tell us about some of it. Hi Mark.

Mark Peplow: Hello.

Geoff Brumfiel: Now few weeks ago, we had you in here to talk about arctic sea ice and the fact that we lost more than ever before and now it appears that we're reaching this year's sea ice minimum. Is that right?

Mark Peplow: Yeah that's right, we can expect to the see minimum either this week or next week and already in the past few weeks, sea ice has actually receded even further in the arctic than really almost all scientists and indeed no computer models had predicted it could. What we're seeing here is an alarming decline in the amount of arctic ice. A couple of weeks ago, we talked about it breaking records as it had gone below 4.1 million square kilometres, which broke a record set in 2007. In the past few weeks, it's dropped to about three and a half million square kilometres and the minimum is going to come up about that level.

Geoff Brumfiel: Why have we lost so much more ice than people thought?

Mark Peplow: Well, in previous years, for example that 2007 record setting year, there was some rather unusual weather conditions which had contributed to breaking of the ice, churning of the water, helping to wear it away and this year we've seen pretty normal weather conditions, there was only really one strong summer storm to hasten the break-up of the pack ice. The trouble is that much of the arctic pack now is very thin first year ice as it]s called so it's only frozen last winter. So, it really doesn't take much to break it apart and disperse it. We've entered really a new regime according to Mark Serreze, the Director of the National Snow and Ice Data Centre in Colorado, which monitors these sorts of things.

Geoff Brumfiel: A new regime, that sounds a little bit ominous for your talking about the climate. I mean are people worried about what this new regime might bring?

Mark Peplow: I mean, there are various predictions about what the consequences are going to be. But, one of the ways that scientists are dealing with is to try and work out why none of their models predicted this happening so fast and it may be that there are additional feedbacks which the models aren't including enough of in their calculations. For example, once the ice melts, the exposed ocean just tends to be darker than an ice covered surface, so absorbs more solar heat, another thing is that we're starting to see over the past few years, far more eddies, large circulation currents in the Arctic ocean which could also be increasing the amount of mixing of the water that brings warmer water into contact with the ice. As to what it all means, well it certainly is bad news for some species, certain types of zooplankton up there in the Arctic cod are increasingly being out competed by other species that are better able to deal with the more ice free sea, but it might also have consequences for parts of Europe and North America in terms of the harshness of our winters. Recently researchers have noted a correlation between the extent of sea ice and a likelihood of seeing if you like extreme cold surges in the winter across those parts of the world.

Geoff Brumfiel: Right, well so being from North America, I'll get my parka out, but Europe has seen another impact from climate change this summer, which was mosquitoes are starting to creep north. I've got to say, in London, we actually had a very mosquitoey summer, I noticed.

Mark Peplow: Yeah we did, our house at the moment in Cambridge is absolutely full of mosquitoes, it's awful. There really are hundreds of them teaming around in the country side and it's not all down to climate change, but climate models do suggest that with a warmer climate in northern Europe, more and more invasive mosquitoes are going to find suitable habitats there. Mosquitoes are actually been increasingly moving into Europe from sort of subtropical and tropical regions over the past couple of decades and they're bringing with them diseases such as chikungunya, dengue fever and now Europe's entomologists and public health experts are joining forces to try and defend the region from this growing threat.

Geoff Brumfiel: So how do you defend a continent from mosquitoes, it's not an easy thing to do, is it?

Mark Peplow: It's not at all. One of the main things, actually climate change is not one of the main things, is the increasing globalization of trade means that species like the Asian tiger mosquitoes which believe me, looks as fearsome as it sounds, it gives them a lot more opportunities to penetrate into Europe. So, one of the best ways that you can deal with them is a better surveillance and in fact the things that you need to surveil largely are the international tyre business.

Geoff Brumfiel: Is that because, I think I read this somewhere, they get caught in water that collects in spare tires, or loose tires.

Mark Peplow: That's right, you have piles of tires in some subtropical clime, the insects comes along lay their eggs in the little bits of water and these eggs are very drought resistant, so they can survive really long distant transport and then they're revived by rain once they reach wherever in Europe. Now these sorts of mosquitoes, the Asian tiger mosquitoes are first seen over Albania in the late '70s but really got a foothold in Italy in '90s and since then they spread around Portugal, Greece, Turkey, around the Black Sea. The trouble is that those are the countries where surveillance is the worst which is why the European Centre for Disease Prevention and Control has rolled out a series of guidelines to help researchers and policy makers basically do better surveillance and to feed all that data into an pan European database.

Geoff Brumfiel: Once you've got the surveillance, assuming Europe can get its act together and get the surveillance, then what?

Mark Peplow: You can look around and see which parts of Europe we know have for example this Asian tiger mosquito, which bits we know don't have it, so the point is once a mosquito outlet is firmly established in an area it's extremely difficult to get rid of it. You have time consuming and expensive spraying programs for example, far better to try and prevent them from getting a foothold. In a lot of more northern European countries, the key is going to be surveillance, down in the southern parts of Europe, around the Mediterranean countries really it's going to be a case of looking at whether risks of outbreaks are greatest and targeting your spraying efforts at those places, just to try and limit the risk of disease.

Geoff Brumfiel: Right so Europe is basically becoming like the upper Midwest of the United States where I came from. Freezing cold in the winter, full of mosquitoes in the summer.

Mark Peplow: That looks like the story, Geoff.

Geoff Brumfiel: Okay thanks Mark and remember all Nature's news content is freely available at

Kerri Smith: Next time, materials that turn heat into electricity and a game that suggests people are cooperative by nature. Aw. I'm Kerri Smith.

Geoff Brumfiel: And I'm Geoff Brumfiel.