It's time for our Q&A, this time from wonderful Edinburgh! This week, what happens if you get pregnant in space? How do chemists make new molecules? And how do antidepressants work? Chris Smith is joined by our panel of experts to answer your questions: Space doctor Christina Mackaill, geologist John Underhill from Heriot Watt University, chemist Lee Cronin from the University of Glasgow and psychiatrist Stephen Lawrie from the University of Edinburgh.
In this episode
05:18 - What if an astronaut is pregnant in space?
What if an astronaut is pregnant in space?
What happens if an astronaut is pregnant in space? Chris Smith put this question to space doctor Christina Makaill...
Christina - As far as I'm aware, no one has been pregnant in space. But if we're sending people to Mars in the future it’s definitely something we need to consider. So I think there's two main things that would affect pregnancy in space and the first one's radiation and the second one is a lower gravity environment.
Radiation can affect fertility in males and females on Earth in things like CT scans, x-rays and things and obviously they will be exposed to a lot of radiation in space which could harm a developing foetus.
Chris - Is that because the radiation damages the DNA?
Christina - Yeah. So it can damage the DNA and the development so if you were to send a pregnant woman to space, the radiation she was exposed to, the foetus we would be exposed to the same amount.
Chris - How much radiation would she see? Because I thought that the whole idea of flying say the International Space Station at the altitude it does, about 400 km, is that it still protected within the envelope of the Earth’s magnetic field so it doesn't see that much radiation, or am I wrong?
Christina - It's a lower amount but it's higher than here. But especially on the way to Mars, for example, would be in deep space and you get much more radiation. And I think I worked out once, because I'm very sad, that it would be something like the equivalent of 2500 CT scans or something which is a lot. Before we send people to Mars in general, and especially pregnant, we would need some sort of barrier to that.
Chris - Because when Curiosity, the rover, flew to Mars, they actually use the radiation sensor for that to look at the dose it got during that journey, and I think the calculation was, were that a human being would have encountered an entire safe working load of radiation for an astronaut for their lifetime on that trip, and back?
Christina - Yeah. Well interestingly, before I talk about the gravity they did a study recently with mice sperm on the International Space Station and they sent up frozen sperm. Then they impregnated mice eggs here on earth and the control was just normal sperm from Earth and they didn't see a massive difference in the structure and the development of the foetus compared with DNA on Earth. So I think they found that space radiation didn't affect the production of viable offspring.
Chris - Could that not... sorry to interrupt you Christina because it occurs to me though that….. if you do that experiment the only embryos that are going to form are going to be ones from sperm that haven't been compromised, because you select for the healthy sperm that can still make a healthy mouse baby compared with if you've got really messed up sperm from radiation then they’re not probably going to be successful, so you might be counting the positives artificially?
Christina - So they think that from the study that the DNA damage was decreased or repaired after fertilisation if that makes sense. So basically it was encouraging that they found that actually once the sperm was fertilised it had a sort of positive effect.
But the other thing is gravity. That's a big thing. We can protect from radiation, we can find a way but we know that lower gravity affects the bones and the muscles and vision things like that. So because astronauts lose muscle mass and they lose bone density how's a foetus going to develop in that environment? Because it's such an important time obviously to develop their bones and muscles and things.
Chris - But the foetus is floating around in amniotic fluid, the bag of watery fluid inside the mother, so does that not create a situation of almost artificial gravity anyway or does the baby still end up sinking in there because it’s sort of neutrally buoyant within the water isn't it, it floats around already?
Christina - I know what you mean, but I still think that the lower gravity might have an effect. I mean we've never tested it in humans so I can't say for sure but I think that would be an issue. So if we could prevent the radiation and sort of make gravity environment similar to earth we could definitely do it. But here will be babies born Mars Mars and, interestingly, Earth will be an alien environment to them and they will develop to Mars gravity so it's interesting, it's an interesting time.
09:18 - How long did the dinosaur extinction last?
How long did the dinosaur extinction last?
How long did the dinosaur extinction last? We asked Geologist John Underhill to weigh in...
John - Well, let's go back to when it actually happened. So the mass extinction event actually wiped out three quarters of animal and plant species at the Cretaceous-Tertiary boundary called the K-T boundary.
Chris - How do you know?
John - Well you look at the fossil record beforehand and immediately thereafter in the strata that are displayed and you see the changes that occur over that. That happens around 66 million years ago going back to the radioactive decay and dating of the earth and so on, and it's actually marked by a tremendous concentration of an unusual mineral called iridium. We don't actually find it in the UK, so we have to look elsewhere for the actual golden bullet, if you like.
Chris - It's like a signature. You're saying that written into the strata, which we can date, is this mineralogical fingerprint if you like?
John - That's right, although not present in the UK. Even recently in the last couple of weeks there have been good reports about North Dakota and some of the samples in that particular area.
Chris - So are you saying then that this stuff is not naturally found on Earth, therefore it came in with whatever 'did' for the dinosaurs because we can see it appearing at the right point in time when we know that event is likely to have happened?
John - So there's certainly an event, that's definitely right. And this is where we get to the nub of the issue because we can date an impact crater. We can identify one in northern Mexico, a place called Chicxulub, and it's located beneath the Yucatan Peninsular and it appears to be the smoking gun, if you like for the iridium.
Chris - How big is the crater?
John - The crater is tens of kilometres across. It caused massive instability in the continental shelf in northern Mexico.
Chris - So how big would the thing that came in have to have been to have made a crater that big?
John - Of that size. I mean, it's the size that you see on the Moon with some of the craters there and so on. But whether it was actually the golden bullet that did for the dinosaurs is really coming back to the nub of the question that has been asked. Because there is another possibility in terms of what caused the toxic atmosphere at that time and that is actually major eruptions, what are called the Deccan Traps in India which occurred over a period of 66 to 65 million years ago. And one of the interesting things about this particular event is, of course, about 150 to 200 thousand years after the iridium anomaly we see a number of dinosaurs and other species staggering on beyond the iridium anomaly, and this suggests that actually there may have been a double whammy that 1) you had the meteorite impact, but moreover the toxic atmosphere was actually being created by the volcanic debris and the like that was going up into the air, and that makes it more consistent with other mass extinction events through the rock record, which have all been tied back to large igneous provinces. So it's probably the two things together. And to answer the question: it was tens of thousands of years, not instantaneous.
How does a battery work?
How do batteries work? We put this electrifying question to chemist Lee Cronin...
Lee - So, a battery just converts chemical energy into electrical energy. That's the kind of textbook answer but it's a lot more interesting than that. Let's go back to the very old batteries, the lead-acid batteries, or even to a lemon potato battery.
Chris - With a bit of copper and a bit of zinc?
Lee - Exactly. So you got these metals and what happens is these metals lose electrons when they react with the acidic contents of the lemon, and that reaction pushes out electrons that go round a circuit. Those electrons aren't lost, they go around the other side to complete the charge, and that push you get is what starts the way the batteries work. So that was determined and then we went into lead acid where the energy if you like comes from solid lead, and as that lead is dissolved in the acid as you take out as you power your lamp or whatever, the lead is dissolved. When its exhausted, there's no more lead left but all is not lost, what you can do is reverse that process and put some electricity back in. You literally push electrons back onto the lead ions, as we call them, and they form back the metal and go back to the electrode. That's a really old-fashioned battery that is really reliable; in fact literally billions of lead acid batteries are still used today.
Chris - But why Lee, can I, not to recharge some batteries? If I buy an off-the-shelf battery in a supermarket that's not dubbed rechargeable I can't reverse that reaction?
Lee - You can. I used to as a kid because you can get them to explode. And the problem is that would have to recharge them so slowly it would just take too long. What I did, I just forced as much power in and, of course, they expanded and they ruptured and all the acid came out and that was rather bad, but I thought quite good fun.
But if you take now a lithium battery, which also is kind of scary because lithium batteries can catch fire. On aeroplanes everyone is terrified about lithium batteries. Well lithium metal’s really really reactive but has a high energy density and that's why they're so good for our mobile phones, and so literally, the lithium metal being dissolved packs a lot of power. So we're spending a long time dissolving that lithium in a kind of plastic bag, in a kind of membrane to try and make sure that lithium goes back again without forming crystals that then cause the bag to expand. Your listeners might have had mobile phones or computers that suddenly warp out of shape, that's because the lithium battery has failed. I wouldn't advocate doing anything with that other than disposing of it correctly because it could catch fire. And the other thing is if you put a nail or something into a lithium battery will catch fire. Basically, there are lots of different developments in these batteries and the quest is to have much higher energy density batteries, a bit like one that would give you something like, I guess, the density of diesel.
15:33 - What makes an anxiety disorder?
What makes an anxiety disorder?
Chris Smith asked Stephen Lawrie what actually makes an anxiety disorder...
Stephen - I'm getting more relaxed as time goes by. So we all feel a bit nervous at times don't we? Such as with exams looming or other relatively common events in life, but the difference between that and an anxiety state is really, in essence, the severity of the anxiety that one feels and how long it goes on for. Most anxiety states, for example, are defined by having anxiety for at least six months.
And then also the fact that the anxiety is in itself distressful and/or disabling. So that's how you distinguish a whole range of different anxiety states from normal anxiety or stress, and then there's a number of different conditions. So generalised anxiety for example is pretty much feeling anxious all the time.
Panic disorder, on the other hand, is having panic attacks, which are relatively discrete episode of anxiety which can be extremely unpleasant. People tend to feel that they are dying or having a heart attack or going to collapse in public.
Then the other types of anxiety are the various phobias. So they affect a very large number of kids - 5 or 10% of kids have a phobia to things like dogs or the dark or spiders. Most of those tend to go away with time but they can persist.
The other thing to say about anxiety is that particularly the phobias are highly responsive to treatment. And a panic disorder and generalised anxiety can also benefit from a number of different treatments.
Chris - What sort of treatment? Do you mean behavioural therapies to help talk people down so they don't go into this? Because my experience of talking to people who had panic and anxiety disorders is that they end up in this vicious cycle where they feel a bit panicky and that makes symptoms like their heart flooding in their chest or they breathe too fast which then makes them feel a bit faint and woozy, and then they think they're having a heart attack so that makes them get even more panicky and it gets worse and worse and worse and they don't know where to turn.
Stephen - Exactly. And you can end up in a Catch-22 situation like that, absolutely. So yes, a variety of cognitive or behavioural strategies can help with anxiety. Very commonly they would include a physical component if you like of encouraging people with relaxation exercises, and the more that you do that, the better you get at it. And the more you can employ a relet station technique if you catch yourself beginning to feel anxious in that situation and it helps you avoid that kind of Catch-22.
Chris - Sort of talk yourself down and say look, I know this is happening because I am making myself nervous, this is because I'm making more and more adrenaline go around in my bloodstream and it’s making my symptoms worse, so because I know I'm doing this if I know that's happening it's not so scary anymore and you can break the cycle?
Stephen - Right, yes. And if those kind of simple measures don't work then there's a range of other treatments that you can apply including antidepressants which we might be talking about later I understand. So they are actually surprisingly effective for anxiety states that haven't responded to those kind of approaches as well.
Does CPR work in space?
How do you do CPR in space? Chris Smith asked space doctor Christina Mackaill...
Chris - So if someone has a heart attack or a cardiac arrest and you need to try and resuscitate them. Very difficult I would think when you’re weightless?
Christina - Yeah. So the problem with giving CPR in space the same way as we do on Earth is, of course, there's no gravity so you be floating around. You could technically restrain the astronaut needing CPR and the rescuer to the ground but that would take time and the longer you leave it before you start CPR, the chances of survival decrease quite dramatically.
So there's three sorts of ways to do on the space station which can be initiated immediately. The first one is called the handstand method and, as it sounds, the rescuer would put their feet on the ceiling of the space station and use their legs to push off it, and they push onto the person's chest who'd been lying on the ground.
The other one is called the reverse bearhug which, again, like the name suggests you would go behind the person needing CPR and given sort of a hug and push in on their chest. And the last one's called the Evetts-Russomano method which involves the rescuer putting their left leg over the person’s right shoulder and then their right leg under the person's left arm so sort of wrapped around their back...
Chris - Like a scissor manoeuvre?
Christina - Yeah. And then giving them chest compressions from the front. So in simulated studies during parabolic flights which the plane - the vomit comet - goes up and recreates microgravity and simulations in air.
Chris - Have you been on it?
Christina - No. I'd love to but...
Chris - I'm not sure - I would probably throw up though. I think most people do, don't they?
Christina - The vomit comet, yeah. I think that's why they call it.
Chris - Even people who are quite resilient still throw up.
Christina - So in these studies the handstand method has been proven to give the best quality compressions. However, the problem is if your small like I am, I probably couldn't do that because I won't be able to reach the ceiling. So in that case the next best one is the Evetts-Russomano method which only had slightly lower quality chest compressions, and the advantage of that as well if your in a position to give ventilation.
Chris - Lee?
Lee - Couldn't they just make a kind of compression chest you know like a corset that just goes on and off, on and off?
Chris - Would that work?
Christina - Yeah. I've been asked that because sometimes in some scenarios on Earth we have to use those if CPR is on going for a long time because the problem with human CPR is that you can fatigue and that can affect the quality of chest compressions.
But at the same time, we still need to know how to do it in a scenario where, again, it might delay time putting this machine on or it might not be available. These things are heavy and expensive as well; we need to bare that in mind when we're travelling to space or on Mars or things like that. The reverse bearhug method isn't great out of all of them. It was the most fatiguing and, as I said, once you get tired the quality gets a bit worse.
Chris - Having had to do a lot of CPR on people in my job, my medical job, it's knackering! And it's knackering when you're on the ground not fighting against all the exigencies of weightlessness. I should think it's probably extremely taxing trying to do that in space?
Christina - Absolutely. So I did a study a couple of years ago and it wasn’t zero gravity, but were simulating Mars and it was exhausting because you weigh less and as you know to give CPR here we rely a lot on our body weight, but because you weigh less you've not got enough strength essentially. So yeah, it's difficult.
23:30 - How do we know the age of the planet?
How do we know the age of the planet?
Chris Smith asked John Underhill about how we know the age of our little world...
John - The answer I gave before was very much rooted in rocks on Earth and where we find them and how we age date them. But of course, there are bits of debris that come in from space, and if we could date some of that debris we can get an age for other parts of the solar system and so that's been done as well. We're using the same techniques with the radioactive decay and that gives us older ages for the solar system of the order of 4.6/4.7 billion years, and even older than that.
Chris - What was here in the cosmic neighbourhood before the Earth formed?
John - Well mainly a lot of debris that was spinning around and starting to amalgamate,and the Earth didn't really get into the state that we know it to be until about 4.5 billion years ago.
Chris - It's amazing to think that actually you can put a date on when we formed in this patch of what was previously empty space with a bunch of rubbish floating around.
John - Absolutely. And if you go to those stable interior parts of the tectonic plates, you can get those age dates from Australia, from the Baltic Shield, from the Canadian Shield.
Chris - Thank you very much, John.
24:56 - How do chemists design new molecules?
How do chemists design new molecules?
Sam wanted to know how we make new compounds and molecules, so Chris Smith put the question to chemist Lee Cronin...
Lee - Okay. There are three ways of going about it. So if you think about chemists they're a bit like architects when designing say a house, but we're restricted by the bonds that we can use, and these bonds are how the atoms get held in a given molecule. The first one is if we know roughly what the molecule looks like, say it’s already existing drug and antibiotic, what we can do is draw that up and then add on the other parts you want. Say you want an extension onto the house, as it were, we can extend on some other atoms and what we would then do, we would then draw that molecule on a computer and then the organic chemist would then -what we would call disconnect it - we would take it apart on certain ways and there are some really good rules we could use. And then go to the laboratory and actually knock that molecule together in a flask, so you actually do reactions to join those bonds up in order and then purify each step. And then, hey presto, you should get a molecule. That's if you know where to start.
The second way I can think of is by trial and error. We just make a whole load of molecules and check what they do. Are they good electrolytes for batteries, or are they good drugs, or are they good pigments? And then go from the property. The other way is to use a computer and do some physics and then say right, I want a molecule that has say I'm going to make an LED with this molecule, so it's going to emit light. So I'd work out what colour that would be and then I would look at how far the electrons have to move and then go backwards. And then the computer would literally spit out a blueprint. The fascinating thing, this thing called inverse design this is really the cutting-edge. Chemists are really beginning to dream molecules in the computer and then take it through the process of molecular architecture.
Chris - But you were in the news in the last year because you also made a robot that could do this and learn as it did it so you could work out from its own mistakes and what did and didn't work; how to make better molecules better make them faster?
Lee - Yeah. I was trying to be coy about selling my own stuff. But in my own lab...
Chris - I'm not just planting that, that wasn't a planted question. I did actually read the paper that you published on this and it seems like it would save enormous amounts of chemists, enormous amounts of frustration and hair loss trying to go down blind endings. Because of course, we are only to make these things because to have those rules to make these molecules because people have relentlessly pursued all these avenues to work out what does and doesn't work?
Lee - So that kind of trial and error method of making molecules step-by-step used to be done by hand and it was kind of an artisan process. And what we've done in my lab is written a programming language that can deploy those steps as you need - a bit like how you would write some software now. And then what we do is reversion control so the idea is that we can send a code to other people to introduce on demand.
Chris - And that means you get precisely the right conditions to get the right molecule?
Lee - Yes.
28:50 - Mangoes and Moonrocks: It's Quiz Time!
Mangoes and Moonrocks: It's Quiz Time!
It's time to put our panel to the test! It's space doctor Christina Mackaill and geologist John Underhill, versus chemist Lee Cronin and psychiatrist Stephen Lawrie...
Chris - Okay so here we go. Christina And John what does the moon smell like? I'll give you three choices.
Christina - I know the answer.
Chris - Oh you know the answer? Do you want to try it? Go on then.
Christina - It’ll be embarrassing if I get it wrong.
Chris - What were you gonna say?
Christina - Gunpowder?
Chris - I had raw eggs, gunpowder, and cheese so I think that's a bing for you guys.
Chris - Plus one to John and Christina off to a flying start, right question two. This is for Lee and Stephen; Which fruit can give you contact dermatitis; pomegranates watermelons or mangoes.
Stephen - Well I think it would be a wild guess for me I'm afraid.
Lee - I would go with pomegranates.
Stephen Yeah, let's go with pomegranates.
Chris - I'm afraid it's not. The mango. The skin of a mango has got chemicals which are very similar to a urushiol I'm told, which is the same chemical in poison ivy that our American listeners are going to be very familiar with poison ivy causes the contact dermatitis that’s photo activated in the skin. So that's “nil points” for you I'm afraid on that one.
Stephen - I learned something at least!
Chris - Team one are in the lead at the moment with one point. Round two. There's plenty of opportunity to redeem yourselves, you two. Round two is called; It's what's inside that counts. Okay so Christina and John question is carrots help you see in the dark? Is this science fact or science fiction?
Christina - I think it's a trick question
John - Because of the war. They wanted people to eat carrots.
ChristinaSo I think it's true but I think it's a trick question. Should we say true?
John - I was going to say fiction because I thought it was during the war.
Christina - I answered the last one so let's go with yours. Yeah. Yeah. Because that's what I'm saying. I think it's a trick question.
John - So I think it's a fiction because there are lots of carrots around. People were trying to encourage people to eat them. They've said you'd be able to see in the dark but in fact I don't think the carotene gives that property.
Chris - So is it right or is it wrong.
Chris - The answer is a false, vitamin A, is good for your vision in general but it does nothing for night vision actually. You're quite right about the war connection. It was a myth promulgated during the war. Actually they wanted to argue that the reason our fighter pilots were so good has nothing to with radar which is the reason they could see so far. They said they ate lots of carrots so they could see in the dark and see very well, well done. Two points so far to team one. Lee and Stephen, humans are the only primates with chins. Is this science fact or science fiction?
Stephen - That doesn't sound true. I think there must be loads of primates with chins.
Lee - Yeah I would go with that
Stephen - So that sounds false.
Chris - They're saying false they got the marks?
Chris - I'm afraid it's not looking good for you two. It's not true. No, humans are the only primates, possibly the only animals with a chin. A chin’s more than just the bottom bit your face is also the bit where a skull protrudes out before it comes back into your lips. Now all other primates actually have jaws that sweep away from the lips. Quite funny because our early human ancestors did not have chins. And I did an interview with a gentleman who was working in Norfolk because there were some early human ancestors that would come up and have holidays in Norfolk, because Norfolk used to enjoy a Mediterranean type type climate some 750000 years ago. And this guy described these people as quite small, small brains. Obviously they'd come for the warm weather and they had no chin. And when this was broadcast in Australia the presenter there said see the British aristocracy obviously goes back a lot further than we used to think.
Lee - Now Chris I come from Suffolk and I could make some comments about people in Norfolk but I won't.
Chris - Should we do round 3 anyways? Tech yes or tech no. Does this technology actually exist? Is the question we're asking, Christina and John question for you. A toaster that prints your face on the bread you put into it. Tech yes or tech no?
Christina - How would that be possible? What do you think?
John - I have no idea
Christina - Should we say yes because we said no last time?
John - I think it’s so outlandish that we should go for it.
Christina - Yeah it's too bizarre to not be true.
Chris - So is it tech yes or tech no they're going tech yes.
Chris - Yes. There's a company and they’re called Burnt Impressions and they will make a custom stencil for you so you can toast your face on slices of bread that you have at home.
John - Is that our prize?
Lee - I know the file format they have for that so I could have answered that.
Chris - So Lee is feeling hard done by, see if you can improve on this one then Lee. A belt that releases air bags when you fall over is that a tech yes or a tech no? a belt that if the unfortunate occasion you fall over rescues you with an airbag.
Lee - It’s ludicrous, let’s go yes.
Chris - Is it tech yes, they’re saying tech yes! Yes you actually scored a point!
Yes it is a tech yes. Hip-air make a wearable belt it detects when a person is falling over and deploys two airbags on each hip. The idea actually it's mainly for older people because of course falls are a serious issue for them and hip fractures cause enormous numbers of ill health and actually mortality especially in wintertime in older people so that's very important.
So you did get a point eventually that's absolutely brilliant but unfortunately you didn't win. So our winners this week for the Naked Scientist Big Brains of the Week is John and Christina. Very well done.
Christina - Thank you.
Chris - Give yourself a big round of applause and I think Lee as the loser, you and Stephen should give them an applause as well.
What is schizophrenia?
Jack wanted to know about schizophrenia, so Chris Smith put the question to Stephen Lawrie...
Stephen - I'm going to start by saying what it isn't. Because very often what people think it is, is exactly what it is not so it is nothing to do with a split personality or having opposing views about things. I think that is a terrible misunderstanding of what it is. And what it is, schizophrenia is basically hearing voices and/or having bizarre beliefs. And beyond that it's hearing certain types of voices and having certain types of experiences or beliefs. So classically people with schizophrenia will hear one or more voices which gives a running commentary on their actions or may tell them to do certain things or may even repeat or sometimes anticipate their thoughts and any of those things you can imagine to be quite, kind of, scary experiences. Over and above that a lot of people with schizophrenia will have persecutory delusions so-called paranoia but those are diagnostically non-specific you get them in basically any psychotic condition including dementia or delirium, but the key beliefs that people with schizophrenia tend to have are, and they overlap with experiences and it's sometimes very difficult for them to describe exactly what it is that they're experiencing or believing, but they have the experience that thoughts are sucked out of their head, so-called thought withdrawal, or thoughts are put into their head, thought insertion.
Chris - Yeah I talked to a lady once who told me she was very worried that her television was tuning into her thoughts.
Stephen - Exactly, They have these basic experiences and then they elaborate them with beliefs to try and explain them, that's a natural thing of what the human brain/mind does isn't it. So we are to a large extent at least kind of explaining machines. And when one has these experiences very commonly people will attribute them to the IRA, MI5, Brexit so far I'm glad to say but it is conceivable that Brexit will get incorporated into people's delusions
Chris - So they basically have an experience that they find frightening or out of the ordinary and then they develop a story to rationalise it for them. So it seems reasonable for them why that is happening.
Stephen - So they may be being poisoned by family, friends, neighbors, or they may be bugged by all these things.
Chris - So all these things you're saying that people's thoughts being tuned into by television, the IRA, that kind of thing they're all contemporaneous aren't they so they presumably is schizophrenia only a 20th century phenomenon presumably not. It must have been people back in history who had it so would they have invented new stories that were contemporaneous to their timeline?
Stephen - Well we don't know. I'm afraid there are no really good accounts of schizophrenia per se from any later than about seventeen hundred or so. The ancient Greeks and Romans for example they did recognise a number of different severe mental illnesses which resemble severe depression or delirium but they don't clearly resemble schizophrenia. That's an interesting but open question it's basically unknowable we can't know for sure whether schizophrenia is a relatively new condition or that is a condition with a relatively different manifestation.
Chris - Can I just chuck in a quick one there because the other thing that's that's risen to prominence a lot in recent years is use of cannabis. And people who use that sometimes develop symptoms a bit like schizophrenia. So or we of the mindset that use of cannabis is a risk factor for getting schizophrenia or does it produce a similar sort of symptoms that then go away when you stop using it
Stephen - Both. So cannabis is a psychoto-mimetic drug. It produces psychotic experiences that resemble psychosis. But if you stop smoking it. Even if that occurs, the psychotic experience will dissipate or gradually disappear. If however you've got that kind of experience and you carry on smoking it you've got a roughly three times elevated risk of getting schizophrenia from the background level of about 1 percent to about 3 percent.
Chris - John?
John - Have the instances increased then, with social media and targeted ads? Because it's like people getting into your head.
Stephen - No it's intriguing. But schizophrenia seems to have a lifetime risk of about 1 percent. And interestingly enough despite all the talk in the media about epidemics of mental health problems for example which are I think, essentially forcefully attributed to social media, there's no good evidence that the rates of anxiety or depression are increasing let alone that social media are a cause of a non-existent apparent epidemic.
Have we done surgery in space?
Chris Smith put this question from Jim to space doctor Christina Mackaill...
Christina - So this is a really hot topic at the moment. For missions to Mars and things like that. So on the space station it'd be too risky. We wouldn't do surgery in space because we have the option to evacuate and bring them back home. For example if someone had an appendicitis it's a great example and it's a hot topic and so we would start with antibiotics. We could use the ultrasound machine to sort of assess the severity but ultimately we could bring them home. When it comes to Mars, we are six months away from Mars when Earth and Mars are at their closest. Anything could happen on the way there and anything could happen whilst you’re there. So we do need surgical capability in microgravity on the way there and once we're there. The thing is with surgery in space; fluids, obviously in microgravity that's a danger. Blood's in body fluids floating around and contaminating the ISS, wound healing is also slower in space. And you know, we just don't have the same resources as we do on Earth if things went wrong. So really interesting sort of debate about this is should we prophylactically remove people's appendixes and gall bladders you know the non essentials.
Chris - Surely not, surely not!
Christina - No, you know is there now is a really interesting debate because you have to weigh up the complications that could occur in space versus the complications of, you know, surgery here. But it's leaning more towards not doing it because there's ethics around it and also post-op complications. And then the probability of it even happening and then we have antibiotics which could obviously maybe cure it anyway so I think they're leaning more towards not removing it but it's an interesting debate.
Chris - The other thing that's foremost in my mind is the infection control implications of doing surgery in space because you chop into somebody you're going to create this aerosol sort of spray if you like, of body fluids and blood. Now when we do this as an operating theatre, gravity intervenes and it all runs off the table onto the floor and onto the surgeon's feet and then you can clean the shoes off and everyone's a winner. But you do that in space, everyone's going to be breathing in bits of you.
Christina - Yeah that's what I mentioned earlier about fluids floating around and stuff like that. So I know they are developing surgical workstations and they're having to take these things into account like watertight vacuums and things like that. And again your immune system sort of dwindles a little bit in space as well. So there's so many things to consider but ultimately, the answer’s yes, where we need to be prepared for surgery
Chris - We're going to have to go there. One wonders though, because you've injured yourself I see with your skiing exploits, you've got your left arm in a sling. What was what was the cause of that?
Christina - Not being very good at snowboarding. Essentially the answer to that question.
Chris - Snowboarding’s got a lot to answer for hasn't it, because the last person, the last guest we had on the programme was the Regius Professor of Botany from the University of Glasgow and he’d broken both of his legs in Chamonix.
Christina - That's where I was this was!
Chris - Must be a bad year for it. But you think often treating people who've had orthopaedic type injuries is a big headache because of weight bearing, whereas in space I suppose there might be a benefit actually, to fixing broken things because people wouldn't have to put weight on them when they're at their most painful.
Christina - Well actually I was reading something about this and it's hypothesised that bone healing from say a fracture actually might be a bit slower in space because we don't have mechanical loading and then we don't have cartilage formation. They're doing a lot of research into that as well because you know the bones become weaker in space, they are susceptible to fracture but actually it may not heal as well either because you don't have the weight of gravity to load and rebuild the cartilage
Chris - So it’d be less painful but a less good healing outcome.
Christina - Yeah exactly yeah.
How do we know what's in the planet?
How do we know what's inside the Earth? Chris Smith asked John Underhill to fill us in...
John - So one way of knowing is actually to drill into the Earth and take rock samples. And this was attempted a place called Kola in the Baltic Shield. The drilling of a nine inch wide borehole took place in 1989 but it only reached 12000 meters.
Chris - 12 km!? That’s a long hole.
John - Yeah. 7.6 miles deep.
Chris - How far into the crust is that though? How thick is the crust?
John - So the crust is different in different places but it can be from 10 kilometers to 100 kilometers. But they were in one of these cratonic shield areas we've been talking about before. So in the center of one of the continents where it tends to be thickest.
Chris - So a good hundred kilometers, so they're literally through 10 percent of the earth.
John - So that is the deepest artificial point on Earth. So we actually, to understand the composition of the Earth, of the planet, we have to rely on remote sensing. So that's using techniques like gravity like magnetics. But by far and away the most effective method has been seismology, and it's to use natural earthquakes that are set off on the Earth's surface or in the subsurface and to see the way in which those sound waves that have been generated by the natural earthquakes, how they pass through the planet and what we're looking at is variations in velocity. We're looking at how changes are recorded as that sound wave passes through the Earth. What that shows us is changes in rock properties, particularly because rocks change under temperature and under pressure. So we have seismograms all the way around the Earth to actually record earthquakes. And that allows us to build up a seismic velocity map of the internal parts of the Earth. And so we can split that out into several different pieces. Basically we see the Earth is layered in sort of spherical shells for want of a better word. We've got the outer part which is the crust as you say Chris. That's actually less than 1 percent of the Earth's volume.
Secondly as we go deeper we go into the mantle and we have a sudden increase in seismic velocity and then inside that we have the core. So the centre of the earth is the core, the mantle makes up a mass of about two thirds of the Earth.
Chris - So that's the lion's share. I was very lucky actually I was in Croatia in Zagreb and I went to the lab of Mohorovičić, who is the guy who did all the amazing calculations to about five or six decimal places by hand in the eighteen hundreds to work out a lot of these sound wave propagations. He was using earthquakes to actually try to do this.
John - That's right. And that Moho is actually the boundary between the mantle and the crust.
Chris - They've got all his old notebooks so it was a real privilege to see that.
46:33 - What's the strongest acid?
What's the strongest acid?
Chris Smith put this burning question to chemist Lee Cronin...
Lee - It's carbonare. It's a really exotic molecule. It's about a million times more corrosive if you like than sulfuric acid, and basically acids are able to release things called protons. And this thing just likes to throw them away a million times better. It's really corrosive stuff.
Chris - So what will it dissolve?
Lee - Not very much because there's probably not enough of it.
Chris - Well I was going to say what do you keep it in then? Because this is a quiz question sometimes isn't it if you have something like that what do you keep it in or how do you store it. The answer is you freeze it because then once it's a solid it can't be active it has to have the particles being mobile to attack stuff.
Lee - Exactly. Yeah. And you want it to be a liquid.
Chris - I've never dissolved and gold, have you ever dissolved any gold?
Lee - Yes we've dissolved a lot of gold and platinum and palladium in the lab in aqua regia, sometimes by accident, sometimes on purpose.
Chris - Sounds like horrible stuff.
Lee - It's very nasty.
47:29 - How do antidepressants work?
How do antidepressants work?
What's going on in the brain when you take antidepressants? Chris Smith asked the University of Edinburgh's Stephen Lawrie...
Stephen - So I’ll try and keep it brief it's quite a complex question. The thing we know for absolute sure that antidepressants do quite quickly, is fundamental to how they work, is they increase the amount of chemicals that are the way that brain cells communicate with each other. So these chemicals like serotonin, adrenaline, noradrenaline, the ways that one nerve cell transfers its electric message to the next nerve cell down the line sort of thing. We don't know for sure whether that's enough, whether there are knock on effects as a result of that that are required for the antidepressant effect and the sorts of things that people think are probably involved. So quite quickly if you can show the effects of an antidepressant in people in terms of being less liable to process negative information or to process information that is neutral in a negative fashion and around about the same time you can also show that certain connections between different parts of the brain are enhanced. So a lot of depression is accompanied by what's called reduced connectivity between different parts of the brain that you can image with various imaging techniques
Chris - And they boot, they sort of pep that back more what we would regard as normal?
Stephen - They boost it, basically, yeah. And I think the best way of thinking about that, getting a handle on it is that a lot of people with depression are struck by brooding and very commonly worrying, or obsessive, kind of, negative thoughts and you can see that in a scanner with increased frontal-frontal conductivity your activation patterns and less long range frontal lobe to the rest of the brain, like connectivity. Antidepressants and indeed ECT interestingly enough.
Chris - That's an electric shock. That's the electric shock treatment? Electroconvulsive Therapy.
Stephen - That is probably the most effective antidepressant and what you would have if you were very severely depressed. They both seem to work at least in part it seems by reducing that frontal-frontal connectivity and increasing more long range connectivity in the brain.
Chris - And just in 30 seconds why is it that if you do experiments on people you can see the effect of drug molecules, of antidepressant drug molecules in the brain within days. Yet it takes say three or four weeks before people begin to feel better?
Stephen - Well that's partly a myth. Antidepressants have very quick effects and that you can see clinical benefits in patients within a few days. Very often patients are the last to notice and that's why they commonly are said to take two, three, four weeks. They actually have quite quick effects; within seven to 10 days usually.