Climate Change Sexes Up Seals

There's tales of gloom and doom everywhere as we hear about the dangers of climate change. Depending who you believe, we're going to drown, boil or freeze in the next few centuries. But new research by scientists at Durham University and the University of St Andrews suggests that for grey seals living on the remote Scottish Island of Rona, global warming has brought some rather unexpected benefits. The seals live in colonies, with lots of females and their pups living with a few dominant males. Warmer and drier autumns have caused pools of rainwater to dry up. The pools are used by female seals for drinking water and splashing around. This means that the female seals have to travel further away from home to find fresh water, removing them from the watchful eye of the dominant male. These little trips away allow weaker males to nip in and get their end away. This isn't just good news for the weakling males, it's also helping to enhance the genetic diversity in the population, which is good for strengthening the species. So global warming's not all bad news, especially if you're a grey seal.

17th Dec 2006

Stardust Reveals Solar System's Secrets

Listeners with good memories may remember that the Stardust mission came safely back to earth in January 2006, bringing with it precious samples or dust from the Comet Wild-2. Like the lump of ice and frozen peas at the back of your freezer, comets are dirty snowballs. They contain matter from the very beginning of our solar system, four and a half billion years ago. Researchers from Imperial College London and the Natural History Museum have used a technique called spectroscopy to look at the mineral content of dust samples from the comet. They found that the comet dust is made up of many different mineral compositions, rather than a single dominant one. The scientists think this means that there was a lot of mixing going on in our early solar system, before the planets formed. This means the solar system was born in much more turbulent conditions than previously thought - like some sort of cosmic blender. Some of the comet dust came from what is now the between Mars and Jupiter, while other particles came from a region much closer to the sun. Because Wild-2 was made in the far reaches of the solar system, some of the dust must have travelled great distances, suggesting a lot more turbulence than previous scientists have predicted. There's a great deal more analysis to be done on the dust samples from Wild-2, but they should reveal even more secrets about how our solar system was made

17th Dec 2006

Smoke Is Poison

Many of us here at the Naked Scientists have done our fair share of lab work, and I've handled nasty chemicals like formaldehyde and benzene with the aid of a lab coat, safety specs, rubber gloves and a fume cupboard. But did you know that these, and a whole host of other chemicals, are also found in tobacco smoke? Cancer Research UK's latest campaign is called Smoke is Poison, and it's highlighting the fact that although most people know that ciggies contain tar and nicotine, around three quarters don't realise there's some really horrible chemicals in there too. Out of the 4,000 chemicals in smoke, around 69 of them are known to cause cancer in humans. These include arsenic, chromium and cadmium as well as benzene and formaldehyde. Funded by the Department of Health, the charity have teamed up with documentary maker Donal McIntyre to make a series of hard-hitting TV and radio adverts, showing the stringent safety measures that lab workers take when handling these chemicals, then capturing their reactions when they realise they're found in smoke. If you want to know more about the contents of smoke, then either text the word "poison" to 84118 in the UK, or have a look at www.smokeispoison.com.

17th Dec 2006

Sweeping CO2 under a carpet...of lava

Researchers are planning to use the porous rocks in lava fields to combat global warming, by locking away the carbon dioxide from power stations. Peter McGrail, from the Pacific Northwest National Laboratory in Washington, and colleagues have found that water saturated with carbon dioxide reacts with volcanic basalts to produce insoluble calcium carbonate, the same material that furs up pipes and kettles. So what goes in shouldn't come back out. "It [CO2] completely converts to solid rock, so leakage is not a concern," says McGrail. Next year the team will pump 3000 tonnes of carbon dioxide, the equivalent of a few hours of power station output, about two thirds of a mile beneath the surface of a western US lava field and then track the movement of the gas below ground and check for leaks. Let's hope their solution is water-tight, or at least gas-tight.

17th Dec 2006

No pain, no gain

A family of firewalkers has helped researchers in Cambridge to track down the genetic linchpin that enables us to feel pain. Writing in this weeks Nature, Cambridge Scientist Geoff Woods and his colleagues have uncovered a gene called SCN9a, which plays a critical role in turning on pain pathways. The discovery was made after the scientists heard about  members of several Pakistani families who were feted firewalkers, self-impalers and dare-devils. These individuals seemed to be unable to feel pain, although in all other respects they were neurologically normal; they could tell hot from cold and smooth from rough, they were ticklish, and they enjoyed curry, although it didn't burn them in the same way that it would a normal person. By comparing the DNA from six of these people, they pinpointed a region on chromosome 2, and then the SCN9a gene, which had been altered in all of them. The gene codes for a pore which sits on the surface of pain-carrying nerve cells and allows sodium ions to enter and excite the cell when it is activated by a painful stimulus. Since the altered channel doesn't work properly, people with two copies of the altered gene, as was the case in these families, cannot feel pain. The team are hopeful that the discovery will pave the way to a new generation of extremely powerful painkillers with few side effects. "This is as important as the identification of morphine receptors," says UCL pain specialist John Wood.

17th Dec 2006

Science Update - Giraffes, Vaccines and Salmon

Chelsea - Sure! This one is an audio question:

Matthew - Why is it that giraffes don't have a stroke when they bend down to get a drink of water?

Chelsea - Excellent question, Matthew. Why don't giraffes have strokes when bending over? Well, we talked to giraffe circulation expert Alan Hargens of the University of California - San Diego. He explained that their brains and spinal cords are surrounded by fluid, just like ours. When they bend over, that fluid rushes to their heads, and squeezes the swelling blood vessels from the outside.

Alan - So when they bend head-down to, say, for example, drink water, the elevation of blood pressure due to the head-down tilt could be counteracted, one for one, by the increase in cerebro-spinal fluid pressure. WALD: Even so, he says giraffes generally don't keep their heads down for long, even when they're sleeping.

Bob - Fascinating. Thanks, Chelsea. Here's another. After hearing about threatened salmon populations, Merrie Smith from Mendocino, California, called to ask why we catch and eat salmon before they've spawned, rather than after. We asked University of Alberta salmon expert Martin Krkosek. He says that when salmon reach their spawning streams, they stop eating and metabolize their own flesh for fuel. On top of that, competing for mates and digging nests for eggs takes its toll.

Martin - So by the time they're actually spawning, and after they spawn, their bodies are really worn out, from fighting with each other, from digging, and they're also usually heavily infected with fungus; they're generally just really gross.

Bob - Very ecological-but not very palatable. Thanks, Merrie. One last one, Chelsea?

Chelsea - OK. Listener Luci Levesque from Augusta, Maine, heard that vaccines are made in fermenters, devices normally associated with beer. She asks, what's the connection? Good question! We turned to microbiologist Agnes Day of Howard University College of Medicine.

Agnes - The principle of using a fermenter is the same for beer as it is for vaccine production.

Chelsea - She tells us that a fermenter is simply a device that grows microorganisms on a large scale. In beer, those microorganisms are the yeast that convert sugars into alcohol. But in vaccine production, they are disabled versions of the disease-causing bacteria or viruses that will ultimately form the basis of the vaccines.

Bob - Thanks, Chelsea. We hope you naked people and all your fans stay warm and have a very happy holiday. Until next time, I'm Bob Hirshon…

Chelsea - And I'm Chelsea Wald, for AAAS, The Science Society.

December 2006

The Science of Colour 2

Anna - Last week, we had a look at colour vision, and the range of pigments found in the natural world. We humans have used colours from plants, animals and minerals to make dyes for centuries. But in order to achieve the fantastic array of hues we see in today's world, we needed a colour revolution. Here's Graham Alcock, from the Society of Dyes and Colourists.

Graham - The first man made dye was produced mainly by accident in 1856 by a gentleman called William Henry Perkin. There were certain chemicals readily available at that time, and they were using the chemistry of coal tar to try and produce a synthetic cure for malaria. In other words, synthetic quinine. And while he was actually trying to produce a synthetic quinine, he had many many failures. But what he did do was to produce one day, a black sludge in the bottom of a flask. He was going to clean it out, and to clean it out he put some alcohol in, shook it up, and he actually produced this beautiful purple colour. So he did some tests on pieces of silk and he found out that they were very fast. In other words they didn't fade in the sun, they didn't wash out etc. So he set up his own little factory. And along with his brother who was his business partner, they started to produce this purple dye which he called mauvine.

Anna - So can we still see this colour mauvine today?

Graham - You can't see the original mauvine because the original coal tar had masses of impurties in it, and the other chemicals they were using as well had lots and lots of impurities. And you can't recreate the impurities.

Anna - The success of mauvine, especially after being worn by Queen Victoria, sparked off competition across Europe. With chemists and industrialists vying to create new dyes that not only looked good, but didn't wash out. But what is it that makes a dye stick in the first place?

Graham - Each fabric will require a particular dye recipe, and also it will more often than not require a Mordent. Now a mordent is a chemical which opens the fibre and allows the dye to actually penetrate really deeply into it. And then it closes up again, which if you like grips it within the fibre and stops it from washing out and fading in the sun.

Anna - However clothes aren't the only thing to benefit from the dye industry. Hair dye is used by millions of people world wide, either to hide grey hairs, or just for a change. Hair itself is made of a protein called keratin, and consists of three main layers: the medulla in the centre, the cortex in the middle and a thin protective cuticle on the outside. But before we look at dyeing hair, where does natural hair colour come from? Here's the London College of Fashion's Judy Beerling.

Judy - Hair colour is actually determined by the pigment melanin, which is produced by cells called melanocytes, that are the base of the hair follicle. And there are two types of melanins: eumelanin and pheomelanin. And they have different colours. And it's the combination of those colours that actually gives you your unique hair colour.

Anna - Melanin is normally passed from the melanocytes, into the hair's cortex. But as we get older, the melanocytes stop working. This exposes the natural white colour of keratin, and the overall mixture of white and coloured hairs, gives the hair a grey appearance. But if grey's not really your colour, permanent hair dye can offer a solution.

Judy - Permanent hair dyes work by a mechanism whereby you mix something that gives you oxygen (in fact it's hydrogen peroxide) with another bottle of stuff contianing ammonia and these dye precursors as they call them. That ammonia has two purposes. It helps the hair to swell so those dye precursors can get into the hair, and it activates the peroxide to produce oxygen, which mixes with those dye molecules. The dye precursors are oxidised by the oxygen and you get slightly larger molecules which get trapped inside the cuticle of the hair. So you get something approaching natural colour in the hair.

Anna - So a guaranteed way to have grey-free hair. But there's another surprising beneficiary to this tale. Graham Alcock again.

Graham - In a royal procession in 1850 you'd have had to kill over 10 million insects to actually produce the dye to dye the uniforms of the people in the procession. So if nothing else, making man-made dyes certainly saved a lot of insects.

Anna - Next time, I'll be finding out how mauvine dyes lead to a headache cure, and how a spot of colour can be used to treat disease.

December 2006

The Star of Bethlehem

Chris - We're joined by Colin Humphreys from Cambridge University. Colin, you think that Jesus is going to have to move his birthday by about 5 years.

Colin - Yes I do. And I also think we're going to have to move Christmas to spring, as well.

Chris - So what's the basis for arguing that?

Colin - Well the key question is, What is the star of Bethlehem, which the gospels say was seen when Jesus was born? And I believe the star of Bethlehem was a comet, and we can look through Chinese records, we have detailed Chinese records. And the only star which fits, between say 20 B.C. and 10 A.D, that sort of period when Jesus might have been born, is a comet which appeared in 5 B.C. The Chinese records say it was a spectacular comet with a very long tail, and it lasted for 70 days. And I believe this was the star of Bethlehem.

Chris - Do you know what that comet could have been? Do we have any idea where it could have come from or how long it stuck around? Is it still out there somewhere?

Colin - Now that's a really good question. The answer is we don't know, because we need more observation. Some comets have elliptical orbits, like Haley's comet, which means it keeps coming back with a certain periodicity. But other comets are just a parabola, which is an open orbit. So you just see some comets once and that's it you never see them again.

Chris - So why do you think that this is a particularly strong contender?

Colin - I think this is a particularly strong contender because Matthew's gospel says the star stood over the place where Jesus was born. And lots of Christmas cards have sort of a star over a house. But what this means is, the Magi who were travelling from Jerusalem towards Bethlehem, they saw the star ahead of them standing over Bethlehem. And there's only one star which can seem to stand over a place and that's a comet. And a comet can appear to stand over a place because it has a long upward pointing tail, which points the head of a comet towards a particular place. And we have in ancient literature, two other examples of comet's standing over a place. Diocasius, a Roman historian, says that a star called Comet stood over Rome. And we can calculate when that was. That was in fact Haley's comet of 12 B.C. And Diocasius said this star stood over Rome. And then Joseph who was a Jewish historian, said a star shaped like a sword stood over Jerusalem. And in the ancient world, comets were often called swords because of their long tails. So we have two other descriptions of stars, we know both were comets and both of them were said to stand over a place. So when the Bible says this star stood over a place, I think it must have been a comet.

Chris - Would it have looked the same, wherever you were observing it from on the earth though? Because presumably the Chinese could see it, would it look the same from the Holy Land?

Colin - That's a really good question. So the place a comet appears to stand over depends on where the observer is. So a comet is low in the horizon, and when the Magi were travelling from Jerusalem to Bethlehem, they would have seen it appearing to stand over Bethlehem but actually it was many many miles away, low in the horizon. So it depends where the observer is.

Chris - What are the other contenders for the star of Bethlehem apart from your comet theory?

Colin - Well the most popular theory is a triple conjunction of Saturn and Jupiter. What's meant by a conjunction of Saturn and Jupiter, is when two planets are in line with the earth, so they all come together and they look as though they're just one planet. And that's a conjunction of planets. And in 7 B.C., this happened three times. So Saturn and Jupiter came together and separated, came together and separated, came together and separated. And that's the main contender for the star of Bethlehem. And the reason is, if you go back to what the astrologers believed, then Saturn was the father God, Jupiter was his Son. So when Saturn and Jupiter came together and separated, people have said a Son has been born to God. And the star background in the sky in which this happened, the constellation's name was Pisces, and the ancients mapped star backgrounds on to regions of the earth. And Pisces was mapped on to Israel in Babylonian astrology. So when you have Saturn and Jupiter coming together against a background of Pisces, the astrologers have said this means that a Son of God is being born in Israel. And lots of people think that's the star of Bethlehem. I think that was a precursor. I think that told them that something was going to happen. But the comet told them, it's happening now.

Chris - Obviously you've said that we may never see this comet again. Is there any way to prove your theory or is it going to have to remain just a conjecture which has some basis for it, along with many others?

Colin - There's certain things which suggest that this is really plausible. One is, you can say how do we know the Magi were interested in this triple conjunction of Saturn and Jupiter. Well we know they were because there's a place which is 30 miles north of Babylon that actually records this triple conjunction. It predicts it, they were pretty good astronomers. And so we know the Magi were interested in this triple conjunction. We also know that people are interested in comets, and another astronomer called Ptolemy, says "A comet in the east means an event is about to happen". So there's lots of things you can put together which suggest this. And the first writer that we know who identified what the star of Bethlehem may have been, writing in the 3rd Century A.D., a guy called Origin, he says "I believe the star of Bethlehem was a comet". So there's a lot of pointers that it really was a comet.

Dave - Mary and Joseph were meant to be going to a Census, to get written up. How does historical records of when they did Censuses relate to your theory?

Colin - Ok well the question of the census is a really good question, and this has puzzled people for a really long time. We have records of when the Roman censuses were. And there were none for that time, for taxation purposes. But another historian tells us that there was a census, not for taxation purposes but a census of allegiance. What happened was, the Roman emperor said "I want everyone to sign up their allegiance that they obey me as the Roman emperor". And the historian Josephus tells us that 5000 Jewish people didn't do this. And they were all slaughtered. So this could well have been the census. And from what Josephus writes, the census was in about 5 B.C.

Chris - That's Colin Humphreys from Cambridge University.

December 2006

Can you beat the Breathalyzer

If you've ever wondered how a police issue breathalyser works - this kitchen science is for you. This week Derek, Mick McReedy the friendly policeman and Ali the Aussie backpacker visit Ely Firestation to investigate science of alcohol, drinking, and breathalysing. Find out if you can get around the test!

What you need

• An Aussie Backpacker
• Some alcohol
• A breathalyser
• A friendly policeman

What to Do

1.   Feed some alcohol to the backpacker. You don't want to make her sick, but you do want her to get a reading on the breathalyser. About four units should do the trick.
2.   Wait. Alcohol takes time to absorb into the bloodstream. About half an hour is a good amount of time.
3. Breathalyse. The backpacker has to breathe into the machine until it beeps.
   Try various ways to get around the test. Mints to mask your alcohol breath, and mouthwash are good experiments to try.

What may Happen

The lungs exchange oxygen from the air into the bloodstream, as well as alcohol from the bloodstream into the air in the lungs. The alcohol that is absorbed from the blood into the lungs is then breathed out into the machine.

The breathalyser has a fuel cell in it. In a car, a fuel cell uses hydrogen and turns that into an electrical current. In the breathalyser, there are a couple of platinum electrodes that use the alcohol in the machine to create the electrical curent. The level of the current indicates the level of the alcohol in the machine, which indicates the level of alcohol in the blood.

Chewing gum has no effect whatsoever on the blood alcohol level and as a result the breathalyser result is no different.
Mouthwash however had a major effect on the breathalyser, because alcohol is a key ingredient. The breathalyser is supposed to read lung alcohol only however because our backpacker swilled the mouthwash immediately before taking the test the machine did erroneously measure her mouth alcohol level and as a result the breathalyser reading was sky high. Not a good way to try and trick the police!