Podcast Transcript

Bad news for dinosaur fans

A paper in this week's edition of PloS One is disappointing news for small boys and palaeontologists, or anyone who's a dinosaur fan. According to a study by Mark Goodwin and Jack Horner, it appears that we may have significantly over-inflated the number of different dinosaur species.

Goodwin and Horner have been looking at dome-headed dinosaurs from North America, known as pachycephalosaurs – they have heads like bowling balls. They've been collecting fossils in Hell Creek, Montana for 11 years, doing a detailed analysis of different species of dinosaur fossils, using techniques like CT scanning and analysis of bone structure.

Horner and Goodwin compared fossils of pachycephalosaurus with another domeheaded dinosaur found in Montana, and a dragon-like skull unearthed in South Dakota, named Dracorex hogwartsia – yes, after Harry Potter's school.

The scientists think that rather than being three different species, the dinosaurs are all actually from the same species, but are just at different stages of sexual maturity. They confirmed their findings by looking at another 17 dino skulls from North America.

This suggests we need to have a drastic rethink about what actually constitutes a dinosaur species.  It seems that much of the confusion has crept in because juvenile dinosaurs can look quite different from grownups of the same species, due to the development of head ornaments like horns, domes and spikes. But scientists may have confused these superficial features with more important underlying similarities between fossils, missing the fact that they are actually the same species.

Horner and Goodwin reckon that up to a third of all named dinosaur species may actually never have existed, and may just be juvenile forms of another species. Other scientists have also suggested this, as a species called Torosaurus was recently dismissed as being a juvenile version of another species, while a number of duck-billed dinosaurs and the fantastically named Nanotyrannus – thought to be a mini T rex – may not be separate species.

So sadly for dino-fans, some of those wonderful names may have to be consigned to the taxonomic dustbin.

1st Nov 2009

Speedy strides due to heel size

When you think about building the perfect sprinter, you might think of long legs and powerful muscles. But new research published in the Journal of Experimental Biology suggests that it's the size of an athlete's heels that might also be important in giving them the edge.

This is research by Stephen Piazza and his team in the US, who was approached by an American Football star to find out if they could help them get the edge over the competition.  When a sprinter pushes off the ground, their acceleration depends on the leverage that they can generate by the calf muscles pulling on the back of the heel, pulling it up and pushing the toes down.

Piazza figured that the best sprinters would have a long distance between the ankle and the back of the heel – making a longer, more powerful lever and pulling the heel up a long way. But when they actually measured how far the athlete's tendon actually moved while pulling up, they got a surprising result.

The researchers discovered that this particular footballer's tendons moved a much short than average distance. So they measured the tendons of a number of elite sprinters and long jumpers, and compared them with the legs of non-sporting people. And they found that on average, the distance athlete's tendons moved with 25% less than those of non-sporty types, suggesting they actually had a shorter “heel lever”.

When Piazza looked into this, he discovered that sprinters compensate for this by contracting their calf muscles comparatively more slowly than those of non-sprinters, generating much more force when accelerating. This is a similar design to many sprinting animals.  And the scientists also found that sprinters toes were on average a centimetre longer, meaning they stay in contact with the ground longer as the sprinter pushes. So although it appears on first glance that short heels might not help you to sprint, short heels combined with long toes and powerful muscles actually help to generate more power.

1st Nov 2009

Liquid identification

If you have travelled by aeroplane recently you will probably have been annoyed by the rules limiting the liquids you can take onto the plane. The problem is that there are various liquids that can be used to make explosives or just a fire, which are hard to detect quickly and easily in the security check.

A group for Julich in Germany think they may have a solution. They are looking at the frequencies reflected in the GHz to 10 THz region of the spectrum, which is the frequency of your mobile phone and upwards. Different liquids have different spectra so you can detect which one is in a bottle, however these frequencies are difficult to deal with and conventional spectrometers are very slow, or they only use a single frequency.

Their solution is to use a Josephson junction, which is a small gap between two pieces of superconductor. The relationship between the voltage across the junction and the current flowing through it changes when you apply GHz  and THz frequencies. So they have been able to shine a variety of different frequencies onto a suspicious liquid and the focus the reflections onto the Josephson junction and work out what frequencies were reflected.

At the moment they have only distinguished 5-6 liquids including water and a variety of alcohols, ketones and water but there is no reason it shouldn't work for more, and they can take a spectrum in a second or so which getting towards a practical speed for testing baggage.

1st Nov 2009

Million frames a second camera

There are many processes in physics chemistry and biology which are very interesting but happen very quickly so they are hard to study. There are many forms of high speed imaging but they work by making conventional cameras faster, which normally involves expensive mechanical systems and they often have a limited light sensitivity because their exposure time is so short. So if you are not careful you have to illuminate the sample so brightly that the light levels will damage it, and they are useless if you are looking at light emitted by a process.

The Megaframe project had just built a camera capable of 1 million frames per second by approaching the problem from a different direction. They have taken sensors called Single Photon Avalanche Diodes, which, as the name suggests, can detect individual photons, making the camera far more sensitive than a converntional camera. These detectors are then connected to timers which can tell you when the photon arrived to within 100ps and be ready to receive another photon 32ns afterwards. They have then made arrays of these detectors up to 128 square, which is a long way from HD video, but immensely better than the alternative of using individual detectors.

The precise measurement of when each photon gets to the detector makes this camera particularly means that it can be used for a variety of forms of imaging which need to know very precisely when the photons arrive at your detector.

This makes the camera useful in a variety of ways, not least, because the rate that some dyes (Oregon Green Bapta-1 ) emit light after they have been given energy by a laser is dependent on the concentration of calcium around them. Calcium is used in the firing of a nerve cell so this means that they have been able to make a video of an indivdual nerve cell firing and as they get more pixels on their detectors, they should be able to video groups of cells interacting.

1st Nov 2009

The most distant object ever discovered

Chris - Now also in the news this week, two international teams of astronomers have described what we can only describe as the most distant object ever discovered.  What they've seen is the gamma ray burst of the star that died when the universe was just 640 million years old.  That’s less than 5% of its present age.  The universe would’ve been only about 9% of its present size and that means the light from that star has been going across space, coming towards us for over 13 billion years.  And one of the people who manage to see was Professor Nial Tanvir who’s at the University of Leicester and is with us now.  Hello, Nial.

Nial -   Yes, good evening.

Chris -   Welcome to the Naked Scientists.  So, tell us first of all, how did you make this observation?

Nial -   So, these gamma ray bursts are actually quite tricky to observe because their main characteristic is a short flash of gamma rays and of course, the gamma rays don't penetrate the earth’s atmosphere.  So, we have to observe them initially with satellites and the current sort of work-horse satellite doing this stuff is one called Swift and that’s the satellite that the UK is partially – built part of the satellite so has an interest in.  So, Swift finds about, on average, two gamma ray bursts every week and it reports the positions on the sky of these events down to the ground within a matter of seconds or minutes so that observers on the ground like myself can make follow up observations using a variety of different large ground-based telescopes.  And it’s by analyzing the information that we get from those ground-based telescopes that we ascertain things like the distance and in this case of course found that it was a record breaker.

Chris -   What actually causes the gamma ray bursts in the first place?

Nial -   That’s a good question.  It’s something that is still enshrouded in a certain amount of mystery, but we think actually, there are a number of different kinds of objects in the universe that can give rise to these sorts of flashes gamma rays.  But in particular, the one that seems to be most frequently are seen are related to the collapse of a very massive star.  So, we have a star that’s maybe 20, 30, 40 times the mass of the sun.  At the end of its life, ceases to create energy in its core and no longer supports  nuclear reactions.  And so, the star just collapses on the under gravity there’s no pressure, radiation pressure to keep it up.  Now, that’s a reasonably common and fairly well understood process but it seems that in certain rate situations, instead of just producing a normal supernova which is what we would expect normally to happen, such a star can also produce an extremely energetic and highly relativistic jet of material that pierces its way after the star.  And if you happen to be sort of lying and looking along the line of site, down the barrel of this jet as it were then you see this phenomenon of the gamma ray burst.

Chris -   Why is it that we’ve not seen one that’s this old before?  Because presumably, the universe has had stars forming and ploughing themselves to pieces and producing gamma ray burst like these for a long time.

Nial -   Yeah.  The problem really boils down to just rarity.  It seems that it’s only very exceptional stars that explode in this way.  And therefore, even in the whole universe, as I say, Swift sees a good chunk of the universe in a sense as it scan off the sky every day, and yet, it still only detects in the whole universe a couple a week.  So really, it just boils down to the fact that we needed to wait a long time until we were lucky enough to spot one at this sort of distance.  If we carry on observing, we may getting more sensitive satellites and scan even more of the sky then the hope is in the future that we’ll find more at this sort of age.

Chris -   What can you learn from the fact or what can you infer from the fact that there was a star burning 600 million years after the Big Bang when the universe was created?  What’s written into that gamma ray burst in terms of the signature and the chemistry that can inform you of the structure of the early universe around that time?

Nial -   Right, okay.  Well, I should say that in this particular instance, gamma ray burst and what – the initial flashes is very bright in the gamma rays, but then the object will then sort of track through the ground-based telescopes is a sort of fading ember.  It’s what we called the afterglow of the burst.  And in principle, the afterglow can give you a great deal of information about the local chemistry and the conditions at the time and in the vicinity of the burst.  And so, that’s very important for example if we find that there is a lot or a certain amount of elements heavier than hydrogen and helium.  So for instance, oxygen, carbon, iron, all the things that we’re familiar with.  If we find that those are present at this time, we know those could’ve only been cooked in the senses of stars.  And so, it gives a very important clue, not just to what’s happening there and then, but what must have happened at even earlier times to produce those heavier elements.

Chris -   Are they there?

Nial -   So that’s the principle.  But on the other hand, the problem is that with the GRB afterglows, they come in a sort of great range of different brightness.  And really, if we’re going to find that sort of information from a gamma ray burst afterglow, it needs to be a particularly bright afterglow and unfortunately, this one wasn’t a particularly bright one.  I mean, it was fairly bright, but it wasn’t bright enough.  I mean, we didn’t really – at the end of the day, manage.  If we had been very lucky with the kind of data that we’d got, then it’s possible we would’ve done it.  But with these things that they go from random times and so, you have to live with whatever telescopes can make the observations at that time and we’ve made the first observations in fact, using telescopes in Hawaii which we sort of triggered from the UK.  But conditions weren’t great in Hawaii that night, so you see the problem.  We obtained enough data to prove that we got this record breaker, but we unfortunately didn’t manage to get good enough data to sort of take it to the next step to do those sort of, you know, refined pieces of analysis.

Chris -   I see.  And just to finish off, Nial.  Can you tell us?  What does this tell us about the structure of the universe at that time, the fact that there was this big star burning at that time?  How does this inform our understanding of the early universe?

Nial -   Well, it tells us that there’s at least one star and of course, one who seems that there were more and we hope in the future, by building up statistics of these things, we’ll be able to really sort of measure the rates of star formation in the universe, even at those very early times.  The other thing it does is it pinpoints the position on the sky presumably, it’s galaxy that hosted this stars.  So, stars forming galaxies and we’d like to know, not only about the properties of stars at this time, but also the properties of galaxies.  And so, the galaxy is going to be far, far fainter than the gamma ray burst because gamma ray bursts is stupendously bright and galaxies only have, you know, a few hundred million stars in them or something like that.  So they're much fainter.  But we can now know the position and knowing the distance, we can go away with all the other facilities that we have without disposal like the Hubble Space telescope, and look really hard for the host galaxy.  And so, that’s certainly something that we haven’t yet achieved, but we hope to do next year is to really search very hard and see if we can find this host galaxy and therefore, for the first time, learn something about the properties of the galaxies which existed at this really early era.

November 2009

This Week in Science History - Tutankhamun

This Week in Science History saw on the 4th of November 1922 the first discovery of the entrance to the tomb of Tutankhamun. The discovery of the tomb in the Valley of the Kings in Egypt is one of the greatest archaeological finds of the 20th century, but science has also had a key role to play in reconstructing the life and death of the boy king.

The discovery of the 4th of November was the top step of a flight of stairs that led down to the entrance to the tomb, now known as KV62. Howard Carter, who led the expedition to find the tomb, knocked through the door at the entrance on the 27th of November. He looked inside, and when asked what he could see, he replied ‘Gold. Everywhere the glint of gold’. The tomb is the most complete ever to be discovered in the Valley of the Kings, with very little looting and damage by grave robbers. Over the next 8 years after the discovery, all of the items in Tutankhamun’s tomb were catalogued and removed to the Egyptian Museum in Cairo.

Until the discovery of the tomb, Tutankhamun had been considered to be a relatively minor figure in Egyptian history. There are conflicting theories for his parentage, but the most widely accepted, constructed from hieroglyphic inscriptions at the ruined city of Amarna, is that Tutankhamun was the son of the Pharaoh Akhenaten, and one of his lesser wives Kiya, not his most famous wife Nefertiti.

The first scientific examination of the boy King’s body was an autopsy in 1926. This was followed by a series of X rays in 1968 and then a CT scan in 2005. The CT scans provided huge amounts of detailed information that have allowed researchers to figure out how old Tut was when he died and possibly what he died from.

CT stands for Computerised Tomography, a process that builds up a detailed 3D image of an object from ‘slices’ of images using X rays. All the ‘slices’ through the object are assembled using a computer program, which then allows internal structures to be viewed in 3D and in detail.

From the development of his skeleton, it is estimated that Tut stood at about 5 foot 6 and was about 19 years old when he died. The CT scans also helped to bust some myths about the boy king. Despite early suggestions that foul play may have been involved in his death, the CT scans showed no evidence for this. They disproved the theory that he was murdered with a blow to the head, and that the shadow on the X rays from the 60s that had led researchers to that conclusion were just due to the position of the skull during the X rays. They also showed that the curved spine that previous researchers had attributed to the condition scoliosis had occurred during the embalming process (as the vertebrae themselves were normally shaped).

It is very hard to tell whether disease has played a role in the death of an Egyptian mummy. DNA testing has been refused by the Egyptian government, and it can be hard to determine what disease someone might have suffered from. Three thousand years ago, people could die from an infection from small cuts and grazes, and from fevers that are not fatal today, that might leave no lasting clues on the body.

Several areas of research have provided evidence for how Tutankhamun died. The CT scans revealed that he had sustained a fracture above his left knee. Scientists from Italy and Switzerland confirmed that the fracture was not a result of the embalming process or later damage, but had occurred during Tutankhamun’s life. The fracture had not healed – suggesting that it occurred in the few days before his death. Botany also played a role in unravelling the puzzle – the flowers on the garland around his neck only bloom in March and April, and given that the embalming process traditionally took 70 days, it suggests Tutankhamun died in December, the height of the hunting season. There were chariots and hunting implements like arrows and spears buried with the boy King, suggesting he was a keen hunter. It is now thought that he suffered a fall, perhaps from his moving chariot whilst hunting, and broke his leg. The leg became infected, possibly with gangrene, and Tutankhamun died a few days later.

Due to his young age when he became Pharaoh, Tutankhamun had advisers to make decisions on how his kingdom should be run. He may not have fought in battles, or brought lasting peace to the region during his short reign, but due to how complete his tomb was, and due to the use of modern scientific techniques to examine the body and artefacts, the discovery of Tutankhamun has given us a detailed view into the life of a Pharaoh nearly 3 and a half thousand years ago.

October 2009