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Podcast TranscriptThe Naked Scientists: Science Radio & Science Podcasts |
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| 9th May 2009 | < Previous Show | Next Show > | ||||||||
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Glycerol diet for long life?
Researchers in the US have discovered that living on a diet made up solely of glycerol could double your lifespan – if you're a yeast, that is.
Previous studies have found that severely restricting calories can also double the lifespan of yeast, but in this new research, published in the journal PloS Genetics, Valter Longo and his team have found a more filling alternative.
The scientists tried feeding glycerol to yeast after they discovered that yeast that had been genetically engineered to have a much longer lifespan also showed increased activity of genes that produce glycerol. The yeast also have low activity levels of a molecular pathway known as TOR1/SCH9, which is thought to be important for extending lifespan in many different animals from worms to mice.
At the moment this work only applies to yeast but it is certainly intriguing. Longo suggests that it may be possible to extend even the lifespan of human by changing the makeup of our diet. We know from previous studies that extreme calorie cutting can extend human lifespan, although – who would want to live a life without cake anyway? Perhaps changing the energy sources in the human diet may also have an effect on lifespan.
References | |||||
| - Wei et al. (2009) Tor1/Sch9-Regulated Carbon Source Substitution Is as Effective as Calorie Restriction in Life Span Extension. PLoS Genet 5(5): e1000467. doi:10.1371/journal.pgen.1000467 | |||||
10th May 2009
Giant shark mystery solved
Basking sharks, the second largest sharks in the world, have been tracked on epic, thousand-mile migrations into the deep waters of the West Atlantic, solving a long-standing mystery of where they spend the winter. Gregory Skomal from the Massachusetts Division of Marine Fisheries in the US led a team of scientists who tagged 25 basking sharks off the coast of New England.
As the satellites began beaming information back to the team they were amazed when the sharks kept on swimming south, into the Caribbean Sea and beyond. One shark even crossed the equator ending up at the mouth of the Amazon River on the Brazilian coast where it hung around for a month.
Their discovery has revolutionised our understanding of these mysterious basking sharks which until now were thought only to live in temperate waters. They have never been seen in this part of the world before, probably because they swim very deep down between 200 and 1000 metres.
The obvious explanation for their migrations is that these cold-blooded sharks need to find warmer water with lots of plankton, their favourite food. But what puzzles Skomal and his team is why the sharks bother going so far south. If food and warmer water were all they were after they could stay in northern Florida. Why bother going all the way to Brazil? One idea they came up with is that the sharks are moving to as yet undiscovered birthing and nursery grounds.
Amazingly, scientists have never seen a young or embryonic basking shark, so we know virtually nothing about how they breed. Previously it was thought that basking sharks form many separate sub-populations but now it seems they are well connected and could form a single ocean-wide population. That raises important issues of how we protect them, since any impacts on basking sharks in one area could have affects on the population as a whole. It could be nations around the world will need to get together and create a global basking shark conservation programme.
And this study just goes to show just how much more we still have to learn about some of the biggest creatures that roam the oceans today.
References | |||||
| - “Transequatorial Migrations by Basking Sharks in the Western Atlantic Ocean” Gregory B. Skomal, Stephen I. Zeeman, John H. Chisholm, Erin L. Summers, Harvey J. Walsh, Kelton W. McMahon, Simon R. Thorrold: Current Biology - 07 May 2009 | |||||
10th May 2009
“Good” bacteria block malaria
Mosquitoes are a major problem around the world, not just because they're annoying, but because they spread deadly malaria which kills over a million people worldwide every year, mostly children in Africa.
This week, researchers at Johns Hopkins Bloomberg School of Public Health in the States have made an important discovery that could pave the way for new ways to tackle these pesky insects. Their work is published in the latest edition of PloS Pathogens.
The researchers focused on bacteria found in the gut of Anopheles gambiae mosquitoes, and discovered that the bacteria help to prevent the mosquitoes from becoming infected with the parasite that causes malaria. When mosquitoes were treated with antibiotics to kill their gut bugs, they became much more susceptible to infection with the malaria parasite. The team also found that infection with the bacteria shortened the mosquito's lifespan.
This is good news because it takes about two weeks for the malaria parasite to complete its life cycle within a mosquito host, so if the mossies are dying earlier, as well as being more resistant to infection with the parasite, it means they're less likely to pass on malaria.
The researchers think that the stimulation of the mosquito's immune system caused by the bacteria also helps to block infection by Plasmodium falciparum, the malaria parasite.
Lead author George Dimopoulos suggests that deliberately introducing the bacteria to wild populations of mosquitoes could be a potential way to control malaria infections. He and his team are currently trying to identify which strains of bacteria trigger the strongest mosquito immune defense against the malaria parasite.
References | |||||
| - Dong et al (2009) Implication of the Mosquito Midgut Microbiota in the Defense against Malaria Parasites. PLoS Pathog 5(5): e1000423. doi:10.1371/journal.ppat.1000423 http://www.plospathogens.org/article/info%3Adoi%2F10.1371%2Fjournal.ppat.1000423 | |||||
10th May 2009
Plant trees. Save electricity.
With all the talk of climate change and trying to cut down our carbon footprint, scientists this week have come up with evidence of a new way to help cut down on electricity bills – the solution may be as simple as planting some trees.
Two researchers from the States, David Butry of the National Institute of Standards and Technology and Jeffrey Donovan of the U.S. Department of Agriculture, have conducted a study looking at how planting trees around your house can help shade it in summer and reduce the need to switch on air conditioners. We all know that trees provide shade and a nice spot to sit under in the summer but this is the first wide-scale study to investigate whether this can translate into significant energy savings in the home. Butry and Donovan studied 460 homes in Sacramento during the summer of 2007 – they looked at what trees were growing around the house and then linked this to the energy bills of each household.
They found that planting trees on the west and south sides of the house decreased summer electricity use, by an average of 5% a year, while trees on the north side of houses actually increased the use of electricity and those on the east had no effect.
Fast-growing trees work better than smaller, slower growing species. They worked out that a London Plane tree planted on the west side of a house could reduce carbon emissions from air conditioners by an average of 30% over 100 years.
And of course trees have the added benefit that they not only shade houses but they absorb and lock away carbon dioxide from the atmosphere too. This study sounds very promising and the authors are keen for researchers in other regions of the world to see if they find a similar pattern.
References | |||||
| - Donovan et al. The value of shade: Estimating the effect of urban trees on summertime electricity use. Energy and Buildings, 2009; 41 (6): 662 DOI: 10.1016/j.enbuild.2009.01.002 | |||||
10th May 2009
Studying Space - The Launch of Planck and Herschel
Dr Anthony Challinor, Institute of Astronomy, Cambridge UniversityKat - Thursday 14th May, all being well, we are going to see the launch of the European Space Agency’s Herschel and Planck missions which are studying the formation of stars and galaxies and background radiation, all sorts of exciting things.
On the show today we are joined by Dr. Anthony Challinor who is here to tell us about the mission and how he is going to be looking at some of the data from it. So thanks coming on the show Anthony.
Anthony - That’s quite alright.
Kat - So tell me what is the mission that you are involved in and what is it doing?
Anthony - So we are involved in the Planck mission and what Planck is trying to do is study what’s called the cosmic microwave background radiation. So this is really the oldest light in the universe. It was essentially created in the big bang itself and what we are going to try and do is study very sensitively the tiny variations in temperature in this radiation when you look in different directions and from that we have to learn a lot about both the early universe and also something about what the universe is composed of, what its geometry is and perhaps even the ultimate fate of the universe.
Kat - Crikey. What’s the actual satellite going to be like? Where is it shooting off to?
Anthony - Planck, its ultimate home is going to be what’s called the second Langrange point which is a very special point about one and half million kilometres from the Earth and it is peculiar in that it rotates at exactly the same angular speed about the Sun as the Earth does. So thermally it’s a very stable environment which is exactly what you need when you are looking for these tiny temperature variations - just about a millionth of a degree fluctuations we are looking for.
Kat - And so you are looking for these tiny fluctuations in temperature, how far back in time are you hoping to be able to look, you know you are hoping that this data will shed light on?
Anthony - So the cosmic microwave background radiation was produced very, very early in the history of the universe and the early universe is very, very opaque but eventually it became essentially transparent about 400,000 years after when we think the big bang occurred and at that time the microwave background effectively decoupled from all the matter in the universe.
So when we look at it today, we are effectively seeing a snapshot of conditions in the universe 400,000 years after the big bang or about 13 billion years, 14 billion years back in time from now.
Kat - And how is the Planck mission special or different from the sort of previous microwave measuring experiments that have been there before?
Anthony - Well so Planck is Europe’s first satellite mission to try and measure the microwave background. There have been two other NASA missions before, the first called KOBE, the second called WMAP which is actually still observing.
Planck is an improvement in that it is much more sensitive. It will observe very, very much wider range of wavelengths and it has better angular resolution as well.
Kat - And if it is so far away from the Earth how is it sending the signals all the way back for you to analyse back in the lab? How long does it take that data to get to you?
Anthony - Well the data is transmitted, it is not transmitted continuously but it’s sort of buffered on board and then there’s an hour or two-hours’ slot everyday when it is all transmitted back.
Kat - And how long does it take to get back to you?
Anthony - What from the…
Kat - Yeah, from the satellite.
Anthony - It takes, it is 1.5 million kilometres so however long light takes to travel that distance.
Kat - I don’t know, any of our listeners would like to do that calculation and tell us, that will be great. Tell us a little bit about Herschel, the other satellite as well, what’s that up to?
Anthony - Okay, so we are not directly involved in Herschel although there are groups in the U.K. that are and what Herschel is basically trying to do is it is looking at dust within the universe.
So it is an infrared satellite and it is basically looking at galaxies that otherwise we can not see in optical light because that the star light is sort of shrouded and absorbed by dust. But that dust is then heated by the star light and re-radiates in the infrared. So Herschel will be able to see those sorts of environments directly.
Kat - I love the idea of a satellite going out looking for dust out to the universe and doing the dusting, ”How Clean is Your Galaxy?”
Anthony - Some people are very interested in dust, yeah.
Kat - Some people are. So where is the mission launching from this Thursday?
Anthony - So it’s going to launch from Kourou in French Guiana.
Kat - And you didn’t manage to get a ticket out there?
Anthony - Unfortunately no.
Kat - And when are the first, the first bits of information going to be coming back? How long is it going to take to get into position?
Anthony - So it takes about three months for Planck to reach L-2 where it will start observing from and the plan then, it takes a couple of months further to sort of settle down and properly be commissioned but after that Planck will do basically two complete surveys of the sky, which will take about 15 months.
Kat - And then you get all the data back and come back on the show and tell us all about it.
Anthony - That’s right, I mean we get the data back essentially as soon as Planck starts observing but it will be probably about three years before there is any real public data release of the cosmological data.
Kat - Brilliant, well we will really look forward to hearing that. Thank you very much. That’s Dr. Anthony Challinor from the Institute of Astronomy here in Cambridge. So if you are a space-excited person then watch out for the launch of the satellite this Thursday.
May 2009
Fizzy Acids - what happens when you carbonate water
Discover what happens when you make water fizzy, why it then tastes so tangy and why this could cause problems for shellfish.
What you need
| A way of carbonating water - a soda syphon or sodastream |
| Some red cabbage |
| Some glasses |
What to Do
Grate a small amount (2-3 leaves) of raw red cabbage and put it into a glass. Add some tap water and then mash it up as well as you can.
Strain out the lumps of cabbage to produce a clear solution. This is your pH indicator, it will behave like litmus changing colour depending on the acidity or alkalinity of your solution (to find out more see this experiment).
Test some of your tap water by pouring a small amount of indicator (3-4mm) into a glass and adding tap water. If the solution is bluey purple then you have hard slightly alkaline water, if it is pink then you have slightly acidic water. We want the water to start off slightly alkaline, so add a little bicarbonate of soda to your tap water until it stops testing pink.
Split your water into two, carbonate half of it, and leave the other half alone.
Now test both the carbonated and uncarbonated water with your red cabbage indicator and see if there is a difference.
What may Happen
You should find that the carbonated water makes the water much more acidic than the straight tap water.
This is the reason why if you taste the carbonated water it has a tangy, sharp - acidic taste.
First a bottle of normal water is added to the indicator, and then some carbonated water from the soda syphon
What is going on?
When you carbonate water you are essentially passing high pressure carbon-dioxide through it and a large amount of that carbon dioxide dissolves in the water.
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The bulb in a soda syphon is basically just a high pressure carbon dioxide tank. | When you screw the bulb into the machine you break the seal and carbon dioxide is released. As it bubbles through the water most of it dissolves. |
Carbon dioxide is far more soluble in water than are similar gases such as oxygen or nitrogen. It can also react with the water to form dihydrogen carbonate (carbonic acid).
This reaction is reversible, it is continuously occurring in both directions, carbonic acid is being made and destroyed all the time. This means that if you increase the amount of carbon dioxide by increasing the pressure you will increase the speed of the production of carbonic acid reducing the amount of gas.
Similarly if you reduce the pressure you will slow the creation of carbonic acid, but it will keep on splitting up to form carbon dioxide gas. This is why if you rapidly reduce the pressure on a carbonated drink it can rapidly turn into foam (see the lemonade volcano experiment).
Why is the carbonated water acidic?
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The CO2 dissolves and reacts with water to form H2CO3 which disassociates to form carbonic acid. |
The hydrogen carbonate can break up (disassociate) in another way, it can split up into a hydrogen ion (H+) and a hydrogen carbonate (bicarbonate) ion (HCO3-).
Any solution containing a lot of free hydrogen ions is acidic. In fact pH (the acid-alkali scale) is just an obscure† measure of the concentration of hydrogen ions in a solution.
The reaction is again reversible so if the amount of hydrogen carbonate reduces so does the amount of acid.
There is naturally carbon dioxide in the air, and this will dissolve in water making it slightly acidic. This is how water can dissolve away limestone to create caves. As we pump more carbon dioxide into the atmosphere it will make water more acidic, this may cause problems for shellfish whose shells are effectively made of limestone.
Are there actually free protons floating around in an acidic solution?
Strictly an H+ ion is a hydrogen atom missing an electron - a proton, which does sound unlikely. In fact what happens is that the Hydrogen carbonate reacts with water to form a hydronium ion (H3O+).
But all the maths works out the same if you think of hydrogen ions so mostly chemists do.
† It is actually pH = - log10( [concentration of hydrogen ions / mol dm-3] ) ... as I may have said, fairly obscure. It so happens that it makes convenient scale and makes other maths easier for chemists.
Written by Dave Ansell
The Great Cam Cleanup
Luther Phillips, Camboaters, and Andrew Walters, RiverCareKat - One factor that has a significant impact on the quality of rivers is human activity. Tonnes of rubbish is just chucked into rivers and canals every year and this not only makes the rivers look pretty dirty, it also does threaten wildlife.
Now here in Cambridge the Great Cam Cleanup is a volunteer project to help keep the river clean and Ben Valsler went along to help out.
Ben - I have spent this morning alongside many other volunteers pulling rubbish out of the River Cam and out of the banks of the River Cam. This had been part of the Great Cam Cleanup, now in its fifth year: an opportunity for volunteers from the community to get together and try and clean up their waterways and their green spaces.
I am here with Luther Phillips who organised this year’s Great Cam Cleanup and also with Andrew Walters from Anglian Water’s RiverCare project. So Luther, why have you organised the Great Cam Cleanup?
Luther - Because I care about the river Cam. I live on the river Cam and I really do have a passion for the wildlife in Cambridge. I live on Stourbridge Common and it is not far from the centre of Cambridge, but on a daily basis I see herons, I see grebes; I see kingfishers, the cows grazing on the Common.
The rubbish that we generate, if we can just be conscious of the fact that we generate rubbish and if we are in a position that we can actually recycle that rubbish, it will create an environment where we enjoy our green spaces and our river more and more.
Ben - And it’s not just the wildlife, is it? I know a great deal of people walk their dogs, people cycle along that route and the fact that it is cleaner in itself makes it more enjoyable for people.
Luther - There are many different river users that obviously use the river: they’re rowers, they’re dog walkers, there is a residential boating community, anglers and obviously everyone has a vested interest in keeping the river clean but the fact that there are so many different walks of life that use the river. It is important that we can bring these people together in an event like this to help them to be able to take care of it, to maintain and to sustain what we created today and in particular, we want to create a legacy that once people see that, you know the next few days of, the open spaces will be clean; the river will be clean in their consciousness and they’ll think well actually we can sustain this.
So it is a very important event that will create a legacy in people’s minds as something that they can sustain.
Ben - Alongside us today I think I have seen at least three generations of people helping to pick up rubbish and to keep the river clean. How many people do actually get involved in this?
Luther - We have had over 225 people who registered in advance for the event. Today we have over 185 signatures and there were people who just came along, took part and disappeared without even just making their presence known. So I would estimate there’s over 200 people that physically took part today.
Ben - And between 200 people it actually makes cleaning this stretch of the river, seem relatively light work but how much rubbish did you pull out?
Luther - Well that’s difficult to estimate because at this stage we have just concluded the event. However, I must say that it is increased on the number of bags that we collected last year. There were over 660 bags of recyclable rubbish last year, 100 and something bikes which were pulled out of the river. There were a vast number of trolleys.
So it’s a fantastic effort by the people of Cambridge who have just spent their time, they sacrificed six-seven hours of the day and they have given something back to Cambridge which is very important. It has created a more cohesive community and it’s empowered people because they are more passionate and they will go away from today and they will talk to their friends, they will talk to their colleagues at work on Monday and I am sure, next year this event which will be on 27th of March, 2010 will be even bigger than it was today.
Ben - I am also joined by Andrew Walters from the Anglian Water RiverCare project. Andrew, you must be extremely pleased to see volunteers coming out in such huge numbers to try and keep the rivers clean.
Andrew - It is great. It has been a really great day to have such local people concerned about their local environment. I mean the river here, the Cam, it is a green wildlife corridor really running through the city and so to have this many people out there, just taking real hands-on practical action to clean it up is really encouraging.
Ben - So do we know for a fact that removing rubbish from inside and around a river is actually good to keep it greener, to keep it cleaner, to encourage the wildlife here?
Andrew - Yeah we do, I mean directly, without being too gruesome, we know that when unfortunately otters are killed on roads and autopsies are performed, a lot of rubbish is found within their guts so it is genuinely polluting the environment and it is a danger to wildlife as well.
More indirectly, I think when people see a river and the riverbanks that are clean and free of litter they are more inspired by them and more encouraged to respect them and they have a sense of ownership of them and really appreciate them as the kind of the urban habitats that they are.
Ben - So what is it that you at RiverCare actually do?
Andrew - RiverCare, our role really is to support communities around the Eastern region to set up local groups which do just this, they are practically working on the local rivers, removing rubbish, removing litter and also doing surveys of the wildlife that is there.
Ben - So it is not just clearing up rubbish then, it’s not literally a rubbish removal project. You also have wildlife surveys and I assume you deal with the invasive species that we have.
Andrew - That’s right. I mean it’s a two-fold thing really. Firstly, the groups do great work in logging where certain invasive species are occurring but also in the instance of Himalayan Balsam which is an invasive weed that’s becoming more prevalent on our riverbanks, in midsummer when it is just coming up the groups do lot of work in removing it from the riverbanks which enables the native wild flowers to grow and prevent some bank erosion during the winter.
Ben - And the wildlife surveys, the bio-diversity surveys that you run, is there anything particularly exciting we could see around here?
Andrew - I think there is, I mean I think an issue is that often when we see a bike or shopping trolley, or some litter in our local river, we think that it’s probably in a poor state but the reality is actually that the biodiversity within the rivers and on the banks is very rich and the rivers are generally in good quality around Cambridge and so don’t be put-off when you see an odd bit of litter around.
Ben - What should people do if they live near a river and want to get involved with making it a happier, healthier place to be?
Andrew - If you are interested in getting involved then please do take a look at our website which is www.rivercare.org.uk, have a look on there and see if there is a local group in your area and join them in doing this kind of thing.
Ben - And of course one essential thing is just not to drop litter in the first place.
Andrew - Absolutely, it’s great to have days like these today with people picking up all this huge amounts of litter but then of course the great way to start is just by not dropping it in the first place.
Kat - And that was Andrew Walters from RiverCare and before him Luther Phillips who organises the Great Cam Cleanup. They were both talking to our producer Ben Valsler about the importance of cleaning up the river for both the wildlife and the local community.
May 2009
The Million Pond Project
Alan Titchmarsh, off the television; Jeremy Biggs, Pond ConservationKat - Now over the recent decades ponds have vanished from our natural environment but the charity Pond Conservation is embarking on an ambitious project to see thousands of new ponds being created in the U.K. Have you noticed the quality of ponds changing over recent years?
I went along to the launch of their Million Ponds Project to find out more and one special guest at the event was gardener and broadcaster Alan Titchmarsh. He is so lovely. So I started off by asking him why ponds are such an important part of our landscape.
Alan - The greatest thing about ponds is that for something so relatively small the wildlife they support is absolutely huge. If you think of the things within the landscape that use a pond, from birds coming down to drink, hedgehogs and mammals coming down to drink. The pond life that’s in the depths there and in the shallows from pond skaters and water boatmen to newts, frogs, toads, damsel flies, dragon flies, you start to build up this list and you think all that just for a little patch of clean water, and that’s the vital thing and the answer is yes, and anybody can make one.
It is so simple - you can do it in an afternoon. Make a small pond, take charge of it; make it clean. You think ‘Well, hang on a minute, how am I going to introduce all that wildlife to it?’ You don’t have to; it will come. The most astonishing thing is that all that wildlife finds you of it’s own accord.
Kat - How would someone go about digging a pond? What would be your top tips for them?
Alan - Oh it’s not just the quality of ponds it’s the amount of ponds. We are losing numbers of ponds that are disappearing. I am lucky enough to live in a village which has a village pond, which is fed by natural stream. So it is wonderful. It stays clean. But they are disappearing. They get filled in and they get polluted, that’s one of the most difficult things, we have run off from farmland and nitrates.
Our clean ponds are now very few in number. I think it’s about 80% of our ponds are no longer clean but it is not difficult to pull that right. I think that’s the great appeal of Million Ponds is the fact that we can address this quite easily, relatively quickly and also quite economically.
Kat - How much fun can you have with ponds?
Alan - People tend to make ponds either too small and they heat up like saucepans on a hot summer’s day or too deep, strangely enough. They think a pond is going to be about four feet… 18 inches in the middle is ample, go to two feet if you want, make sure it’s got shallows so things can get in and get out and there’s more life in the shallows of pond than there are in the depths.
If you have a 3-foot deep pond there’s nothing much living right down the bottom there at all, one or two amphibians might hibernate there but most of them hibernate outside the pond, I mean under stones and things like that.
So it’s so easy with a decent liner that can’t get perforated and a bit of under lay, a bit of soil on top of it and then you can either fill it or you can be very patient, and wait for a rainy day. It’s so easy, it’s easy as that.
Kat - So ponds are easy to make and they are more fun than watching TV. To find out more about the Million Ponds Project I spoke to Jeremy Biggs, Policy & Research Director at Pond Conservation.
Alan - My big thing about ponds is exactly that and that to me is the essence of conservation. There tends to be a lot of finger wagging in conservation terms and the onus is on you and it’s a weighty responsibility. It is the greatest joy in life to do something which improves that nasty thing called the environment. I am certain my life’s work is to find a better word for environment. I like landscape, that’s much nicer.
It is so joyous you introduce children to gardening too, and that’s the sort of sharp end, if you like, of conservation, just dabbling around in the soil with a trowel making a pond, looking at pond life. They are entranced by it and that’s far more and I say this as someone who knows, far more to watch in a pond than there’s on telly.
Kat - So ponds are easy to make and they are more fun than watching TV. To find out more about the Million Ponds Project I spoke to Jeremy Biggs, Policy & Research Director at Pond Conservation.
Jeremy - Million Ponds Project is a five-year initiative to add about 4,000 new ponds to the countryside and in the longer term to double the number of ponds in the British landscape to get back to the million ponds or so that we had at the beginning of the 20th century.
So over the next 50 years we are going to make 500,000 new ponds to replace those old ones that we have lost.
Kat - It sounds ambitious. Who is going to help you do this?
Jeremy - Well there are all sorts of people making ponds. It is actually not as ambitious as it sounds, I would say. When you look around the countryside it’s about 20 ponds a day being made by people already. So that’s five or 6,000 a year. So actually all we need to do really is just to capitalise on that work that they are already doing out there and make it a bit better and make them help people to get the best of the pond creation, of work they are already doing very often.
The people would be doing it, really again that’s all kinds of people, from big organisations like the R.S.P.B., the National Trust, the Environment Agency, right through to the individual land owners and land managers. People can even make ponds at home in their garden as well.
Kat - And what are the risks of not bringing by the ponds? How we see the environment change as a result of losing so many ponds?
Jeremy - There are so many things that live in ponds, about two-thirds of all types of fresh water plants and animals there are can be found in ponds. So if you lose those ponds and in particular if when so many of them damaged by pollution and other impacts, so it’s about 80% which are in poor condition. When so many are damaged and degraded, that means there’s just less habitat available for a whole range of fresh water plants and animals, many of which have now become rare, most of the things which need clean water are struggling now-a-days. There’s just nowhere left for them to go.
So by putting back that clean water we hope to take the pressure off a bit, let things spread out again, just to give them the refuge.
Kat - And finally tell me about your favourite pond?
Jeremy - Well I have got lots of favourite ponds, actually to be honest, almost any pond which is clean and unpolluted, has a rich stands of plants under the water. When you take a pond that you dip it, you see lots of different kinds of animals in the water. There are lots of amphibians around. These are not so common these days.
So almost anywhere where you see something like that, that’s one of my favourite places. Of course you can see these dotted around the countryside still from the south of England, from the Lizard Peninsula, in the far south west, right through to the far North West highlands of Scotland. You can find them dotted around. To be honest, those are really all my favourites.
May 2009
Invasive Alien Species
Dr David Aldridge, Cambridge UniversityHelen - Well, in the studio now we have Dr David Aldridge from Cambridge University and he works on the understanding how the ecology of invasive species affects our rivers and fresh waters and finds out ways of trying to stop them. Hi David, thanks for coming in to the studio.
David - Hello Helen. It is a great pleasure to be here.
Helen - Fantastic. Well first of all, what do we really mean by invasive species and why are they a problem?
David - Most people understand the term ‘invasive species’ to relate to species which are not native in a new area but which also have a negative impact on the ecosystem.
Helen - So we can have invaders that we don’t notice or they generally stand out, we know that they are there and that’s why they are a problem?
David - We sometimes talked about this ‘Tens Rule’ that about ten per cent of the species which invade a new system don’t establish and then only ten per cent of those that do establish actually have a measurable impact so there’s lots of things around in our rivers and elsewhere and in our environment which we don’t really notice and don’t really have a measurable impact.
Helen - And the things that get to the British waterways and are a problem, what sort of things, are we are seeing arriving in our shores?
David - Well we have just finished an inventory of all the non-native species in Britain’s waterways and we have…
Helen - How many are all there?
David - There’s about 120.
Helen - Well, okay.
David - But there’s lots waiting to come and we are trying to help predict which is going to be the next big problem but some of the really big problems throughout the U.K. at present in the Cambridge area…
Helen - You’ve got something in front of you there I see. You’ve brought some dead critters I am pleased to say, into the studios. Well what have you got there?
David - I have got a little menagerie of goodies here and I have got some zebra mussels, I have got a signal crayfish of North America and I have got a Chinese mitten crab.
Helen - Excellent, we heard a little bit about the zebra mussels last time you were on the show a couple of years ago and I take it they are still a problem very much within the U.K. waters.
David - They have become an increasingly larger problem and actually they have got a very close relative, something which belongs to the same genus, something called the Quagga mussel which is building up in the river Rhine and almost displacing the zebra mussels and so that’s going to arrive with us very soon.
Helen - So another invasion of something that’s getting rid of another invasion, and why are they a problem? What’s wrong with having these zebra mussels? They look rather beautiful I have to say. The collection you’ve got right there, the stripey and you know, they don’t look problematic. They look quite small and sort of size of thumbnail, I mean why should that be a problem in the wild?
David - You are right they are beautiful but unlike our native fresh water mussels which just sit in the bottom of rivers with their foot digging into the mud zebra mussels have a beard, a byssal thread which is like the marine mussels that you eat.
Helen - Moules Mariniere, tasty, lovely...
David - Indeed. So zebra mussels are able to sit on solid surfaces and they can attach to each other and sit in dense layers so they can foul pipelines and drinking water supplies, cooling systems to power plants, irrigation systems but also they sit on our native wildlife and one of the things they really threaten such as this specimen I have got in front of me, are our native mussels which provide a really good substrate and they choke them and cause them to die.
Helen - Because that’s a huge mussel you’ve there and I can hardly see it, it’s kind of covered in smaller zebra mussels, that’s incredible. And then the crayfish you’ve got there, that looks quite tasty. Can we eat those?
David - We can and that’s the reason they were brought over here. The American Signal crayfish was brought over in the 1970s as a commercial aquaculture food and the problem with these crayfish is that they can walk over land so they escaped out of these little ponds they were put in and they can move into the wider environment.
So they are very good at sort of changing the ecosystem through feeding on the bottom rooting plants and macrophytes and they dig burrows which can cause destabilisation of the banks but perhaps of greatest or immediate concern is that they carry a fungus, something called crayfish plague which kills our native crayfish species but these are pretty resistant and the American ones are pretty resistant too.
So we have had for instance in the Cam in 2000 there was an outbreak of plague which wiped out native crayfish from about 20 kms of river within weeks.
Helen - Wow, and could we kind of combat that fungus? Is that one way of looking at sort of the problem or do we really just need to get rid of the invasive crayfish themselves?
David - The Signal crayfish and the other non-native crayfish we have in Britain are a real problem. Nobody has really found a way of controlling those. The environment agency have tried sort of heavy duty trapping, people tried pheromone traps to try and skew the sex ratio in the rivers.
One of my sort of observations is that certainly in sort of some of the chalk streams the river Shep, for instance in Cambridgeshire where you have got cooler headwaters the fungus seems to be less virulent there and so they could be refuges for the native crayfish in those areas but generally speaking there’s no known way to eradicate this.
Helen - So far we don’t know what to do about them and you have got another crab in front of you and you said that was a Chinese Mitten crab, did they come from China?
David - Yes, and quite a few of our non-native species have come from China. They are very popular food items in Asia and the Chinese mitten crab is quite tasty but unfortunately in China it also carries a fluke which is harmful to humans.
Helen - So that’s like burrow into a liver or something.
David - That’s right, yeah. The things that flukes usually do.
Helen - Nasty things, okay. But you also work in China. You are looking at similar sort of issues and invasive species out there?
David - Yeah, I have been working in China for the last five years with the World Bank and there the focus is on sort of trying to rehabilitate some of the world’s largest but most polluted freshwater ecosystems. So I am working on the border with Tibet in some of the China’s largest lakes that were created during the Himalayan uplift and…
Helen - How big is the lake?
David - Lake Dianchi, which is the largest one we work in, is about 300 square kilometres. The second largest one we have lake Fuxian, which is 160 metres deep. They are pretty big things.
Helen - Pretty huge then, yeah. So there’s a lot of space there for lots of creatures to get into?
David - Yeah, I mean historically these lakes we have discovered had massive endemism. We have found in the areas sort of 50 species of fish which you find in these lakes and nowhere else but with habitat degradation we are discovering these ecosystems have really crashed. Over 90% of the biomass in these lakes are non-native organisms, things like introduced Carp, the water hyacinth which totally smothers the lake surfaces.
Helen - So only ten per cent of the living stuff in those lakes is stuff that should be there really.
David - Yeah, and actually a lot of the stuff that hasn’t been described before, the fish have been well studied but when I went out the first time five years ago I put a dry suit on and jumped in to the water which a lot of Chinese people tend not to do. I rolled over some rocks and I found a new species of leech, a huge thing with green and purple stripes…
Helen - Oh gosh, that sounds horrible.
David - All sorts of things, yeah.
Helen - So amazing creatures there.
David - Yeah, absolutely.
Helen - And finally really what can we do to try and protect ecosystems from these invaders? It sounds like there’s an enormous problem in China, how on Earth can you start to actually do anything about that?
David - A lot of it is education but the problem is that until we understand and we can conduct risk analyses and identify what invaders are going to be the most likely next big problems. It is very difficult to develop policy and decide what we should be doing to stop things moving around. We have to understand the vectors, there is implication for climate change on this and whether a new species might be better suited to invading things. So all sorts of complicated issues to consider.
Helen - It sounds like a very thorny issue indeed but thank you very much for coming and introducing us to the world of invasive species. That was David Aldridge. He is from Cambridge University and works on understanding the aliens that are invading our waterways.
May 2009
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Is the Sun Alive? Andy in Northampton |
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We put this to Kat Arney.
We also put this to Dave Ansell, for whom physics is a strong point!
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May 2009 |
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Can you ask if the people working with mosquitoes (the news story Kat covered earlier) had considered using the bacteria in their guts to develop a protection for humans or whatever? Keith in Norwich |
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We put this to Kat Arney: Kat - It is an interesting question. I think this works to a very early stage. The protection from the bacteria for the mosquitoes is really due to their immune system rather than anything special about the bacteria themselves as far as I know at the moment. So it’s certainly an interesting question and I don’t think it would work if it infected humans with bacteria either but certainly an interesting question, thanks Keith.
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May 2009 |
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Can you do aerobatic stunts like a loop-the-loop or a barrel roll in large aeroplanes such as Airbus A380s and Boeing 747s? Dave, Essex |
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We put this firstly to Disk Schleh, of Boeing Commercial Airplanes in Seattle, Washington:
We then asked Peter Merton, Resident Research Officer at the Imperial War Museum at Duxford.
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May 2009 |
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"Can you do aerobatic stunts like a loop-the-loop or a barrel roll in large aeroplanes such as Airbus A380s and Boeing 747s?" Once. - Bored chemist - 5th May 09
I would imagine any stunts would have to be done quite slowly, if at all, as the large planes won't be very maneouvreable. That said, I have seen a DHL-branded 747 cargo plane flying extremely slowly and extremely low over the sea at the Eastbourne Airshow... - techmind - 5th May 09
Is he asking about people inside the plane or the actual planes doing the tricks?
- Chemistry4me - 6th May 09
As long as the manoeuvre is within the g ratings of the aircraft, no problem. A barrel roll is an approx 1G manouevre. +3g to -1 appears to be a typical recommended operating envelope on a very quick web search. That has intrigued me, and I may update this post further. Here is the most famous example: http://www.youtube.com/watch?v=WJ546BEps-M - Edster - 6th May 09
For the most part, nope. The vid that Edster links to is worth watching, and listening to; you'll hear Tex Johnson clearly describing the maneuver he performed in the Boeing 707 prototype as a Chandelle. While this may look a bit like a barrel roll it's actually a lot different and isn't actually classed as an aerobatic maneuver but as a turning maneuver. Having said that, it's not usually extended so far. There are three main reasons why an airliner can't/shouldn't perform aerobatics: The airframe isn't designed to handle the stresses, they lack sufficient power (unless empty), and the flight controls lack sufficient authority to maintain the maneuvers. Let's use a true barrel roll as an example, where the aircraft rotates about its longitudinal axis. As the aircraft starts to roll, a centrifugal force is applied sideways to the engine nacelles, and while the nacelles are designed to transfer the power generated by the engines to the wing, the forces they must withstand are always along the axis of the engine, not sideways to it. Thus, as a consequence, unless the roll is very slow, the centrifugal force will detach the engines. However, trying to roll the aircraft very slowly brings its own problems. Because gravity always acts downwards, regardless of the attitude of the aircraft, as soon as the wings are not level they generate less lift than normal, and of course, when the wings are vertical, they generate no lift at all. In a slow roll then, as the roll approaches 90 degrees, the only things generating any lift are the fuselage and the rudder, and to get sufficient lift from them would require a relatively high Angle of Attack (AoA - this is the angle of the lifting surface relative to direction of movement through the air), which as the axis of the aircraft have been translated 90 degrees, is equivalent to extreme yaw, which in turn results in very high drag. As the airliner approaches this point it'll find that the rudder lacks sufficient authority to maintain the AoA needed, and the induced drag, combined with effective yaw relative to the engines, effectively reduces the available power. There is also a very good chance that the AoA required could stall the tailfin/rudder, leaving no effective flight controls. A loop is more feasible, for a lightly loaded airliner, because the major forces act in the 'normal' directions i.e. along the axis of the aircraft, and effectively downwards, even when the aircraft is at the top of the loop. Even then though, the size of the loop must be carefully chosen; too tight a loop will increase the G-forces experienced to the point where the aircraft may either break up or end in a G-stall (this is where, due to G-forces, the effective weight of the aircraft increases beyond the lift available to support it). Too large a loop, on the other hand, means that the aircraft won't be able to maintain sufficient speed as it climbs up the loop and will stall. There are also issues concerned with things like the thickness of the skins covering the airframe; these are no thicker (and stronger) than normally needed on an airliner to save weight, but all the aerodynamic forces that we've been discussing act via the aircraft skin, and once the skin strength limits are exceeded the skin will start to disintegrate. Some large military aircraft have been rolled and looped, but only the very strongest ones; the Vulcan being a good example. It was, in any case, a very rigid and strong design, but the engines were sited inboard, close to the fuselage, so suffered relatively little during rolls. The Low Altitude Bombing System (LABS) used by Vulcans and developed during the cold war after ground-to-air missiles developed that could reach the highest flying bombers, involved approaching the target at low level, typically a few hundred feet agl, and then pulling up in to a loop, with the bomb being released just before the aircraft reached the vertical. The bomb was therefore lobbed up in the air, and towards the target, while the bomber continued on it's loop, rolling back level at the top of the loop and facing away from the target (I was lucky enough to see this demonstrated at an airshow and it's quite a sight - there are some clips on u-tube). - LeeE - 10th May 09
This edited piece of film inserted in the interview has caused so much argument on forums. The edit does not align the pictures with the voice over or give an explanation of the terms The description in the interview of a roll, preceded by a Chandelle applies to this better quality piece you may find here: http://www.avpics.de/mov/civ/tex_roll.avi My post started from my memory of 25 years ago I`m sorry I was lazy and picked the first google illustration. In the film you can see a powered banked climbing turn, followed by a roll, in which the axis of roll is substantially higher than the axis of the fuselage. This still equates to a chandelle followed by a barrel roll in all the limitations of both definitions I`m aware of that haven`t changed since after the web. If the roll axis falls within the fuselage area, it is a flavour of aileron roll as there is no helical movement about an external axis. Sorry. The manouvre was repeated on the same flight too. 25 years ago with some other engineer friends over beer, we discussed the same topic, one of our number had then become a Resarch Aerodynamicist, and his pronouncement was any 1G manoeuver is unconditionally safe, and having seen that film (incidentally described as a barrel roll) as part of his undergrad aero degree, said he admired the bravery of the pilot; not for the move, but for the chewing out on landing by those that didn`t understand how safe it was. Airliners.net have a general for g not too far from that I remembered: http://www.airliners.net/aviation-forums/tech_ops/read.main/233503/?threadid=233503&searchid=236256&s=aerobatic#ID236256 This is normal flight envelope. There are transient g ratings including g bump landings in excess of these by far larger margins than 150%. ALL of the aircraft must be able to withstand this, from the overhead lockers to the wings and fuselage, the fixing of the cabling inside the aircraft etc. Oh and the engines. It would appear that more modern airliners will not be able to do any "aerobatic" manoeuvres due to set limits in the fly by wire, for example most airbus aircraft have a fixed bank limit of around 60 degrees so a roll would be off the menu ( except on the inflight catering) So for those 2 mentioned it looks like no. Sorry. no rolling aibuses at shows then. - Edster - 10th May 09
One thing that nobody mentioned- Concorde could do barrel rolls; they actually did it. During the test program the French test pilot (I think Turcat) was sitting next to the British one (Walpole) and he rolled it; and then invited the British pilot to 'unroll it' again, so he did. They didn't ever do it with passengers onboard though; strangely they thought it might make them nervous. See: http://www.youtube.com/watch?v=KYQS3qAIjAo But as others have implied, I'm pretty sure that all aircraft can do a barrel roll or similar; this is a maneuver that can be done at 1g throughout; and basically all aircraft can take it; although you might have to turn off some of the computers in some of the modern ones. - wolfekeeper - 13th May 09
If memory serves me, they should be rated at +3\-1.5g's. If you can maintain these limits they will all do it. I have always been told that the 707 is structually sound enough to do the loop, but the circle, up and down air space needed to complete it the 707 wouldn't make it, just can't fly high enough to do it and not strong enough to pull out at the end of it, the harder you pull the more g's created, eventually the wings say, enough for me, I'm going somewhere else.
See the whole discussion | Make a comment- Erbie - 9th Sep 09
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Certainly the wings of the airplane would be put under quite a bit of stress and some of the tail structure and so forth, doesn’t mean it couldn’t do it but they were not designed that way and they were certainly not certified with that in mind. In the early days of the jetliners when the jetliner was being developed at the Boeing company in the 1950s there was a prototype called the 367-80, that was the 707 prototype and the original test pilot on that airplane was Tex Johnston and one day he was asked to fly the aeroplane over a major event here in Seattle which was called the Hydroplane Races, so he did in fact fly the aeroplane at a fairly low altitude over the crowd but then he decided to really impress the crowd so he did a barrel roll with that airplane, much to the surprise of the Boeing officials who were watching from down below.
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