Features

Today saw the ESO give the go-ahead for work to begin on a series of roads on a mountain in Northern Chile.

But these aren’t just any roads; they will give access to Cerro Armazones, the site that has been chosen for the European Extremely Large Telescope (E-ELT).

E-ELT is planned to be the largest optical and infrared telescope in the world: it will be tens of times more sensitive than any current ground-based optical telescope.

Oxford University scientists are taking a lead role in the instrumentation for this £922m (€1082m) project, so today’s announcement from the ESO, which included funding for the roads and the adaptive optics mirror, is welcome news – even if a final decision to build the telescope won’t be made until mid-2012.

Niranjan Thatte of Oxford University’s Department of Physics led a European consortium that designed the E-ELT's HARMONI spectrograph, one of the proposed telescope's key instruments, he told me back in October:

‘HARMONI is an integral field spectrograph, simultaneously providing images and spectra of astrophysical objects in unprecedented detail, giving a fivefold improvement in spatial resolution over present-day telescopes.

'Combined with the immense light-gathering power of the E-ELT, it will enable ultra-sensitive observations of distant and nearby galaxies, super-massive black holes, young star-forming regions, extra-solar planets and other exotic objects.’

Yesterday, prior to the announcement, Isobel Hook of Oxford University’s Department of Physics, who chairs the E-ELT science working group, told the Today programme's Tom Feilden:

'The main improvement with this telescope over anything that's gone before is its size. The huge area allows you to collect light from much fainter more distant objects, while the diameter is what gives you the superb resolution - the sharpness of the images.'

With events at the LHC likely to dominate the headlines next week and next year, it’s worth considering just how much of an advance astronomy’s biggest science project could be:

The improvement in terms of resolution has been likened to the leap from the naked eye to the first telescopes used by Galileo and Harriot in the 1600s.

You can read more about HARMONI in our news story, whilst for more about E-ELT, and to listen to an interview with Niranjan, check out Tom Feilden's Blog.

It’s still a long road ahead for the E-ELT but, if approved, construction could start next year, with the telescope being operational early in the next decade.

Our galaxy is a relatively quiet neighbourhood with the supermassive black hole at its heart gently dozing: or is it?

The recent discovery of huge gamma-ray emitting ‘bubbles’ around the Milky Way is challenging this assumption and posing a new puzzle: just where do these bubbles come from?

Philipp Mertsch and Subir Sarkar of Oxford University’s Department of Physics recently reported in Physical Review Letters a model that could explain the origins of these strange phenomena. I asked them about bubbles, ‘feeding’ black holes, and how their ideas could be tested…

OxSciBlog: What are 'Fermi bubbles' and where are they found?
Philipp Mertsch: The 'Fermi bubbles' are gigantic structures above and below the centre of our Galaxy which were discovered by astrophysicists at Harvard in a gamma-ray sky map made by NASA's Fermi satellite.

The bubbles extend ~50,000 light years above and below the galactic plane, i.e. they are about the same size as the disk of the Galaxy. A correlated structure can also be seen in the X-ray map made by the ROSAT satellite.

It may seem surprising that such huge structures have gone unnoticed earlier - this is a testimony to how advances in astronomical instrumentation lead to serendipitous discoveries!

OSB: Why is it important to understand them?
Subir Sarkar: The bubbles are important for a variety of reasons. First, their origin is very likely related to an energetic outflow from the the supermassive black hole lurking at our Galactic Centre - it is supposedly not "feeding" but clearly was doing so as recently as a million years ago. Understanding the mechanism of their gamma-ray emission also holds clues as to what is powering them.

Moreover this region of the sky is a prime target for dark matter annihilation signals - while the bubbles are themselves very unlikely to be due to dark matter annihilations, we need to understand them in meticulous detail if we want to look for the much smaller signal in gamma-rays expected from dark matter.

OSB: How have scientists previously tried to explain them?
PM: So far, scientists have considered the same processes that are believed to produce gamma-rays in astrophysical sources, for example decays of neutral pions created by interactions of high energy protons with ambient matter, and inverse-Compton scattering of background photons by high energy electrons.

High-energy protons are certainly present in the disk of the Milky Way, but it is not easy to explain how they could be transported to such large distances from the disk and be contained inside the bubbles for billions of years.

The problem with electrons is that they lose energy rapidly and would need to be reaccelerated - it has been suggested that this happens at hundreds of shock fronts inside the bubbles. However, there is no evidence for such an onion-like structure, in fact, the bubbles have a smooth surface and a well-defined, sharp edge.

OSB: What do you suggest may have produced the bubbles?
SS: The X-ray data from the ROSAT satellite suggest only one shock front which delineates the outer edge of the bubbles. This shock produces turbulence in the plasma behind it which can accelerate electrons to very high energies through a stochastic process first discussed by Enrico Fermi.

These electrons then transfer their energy to low energy photons from the microwave and infrared backgrounds as well as starlight, producing the gamma-rays observed.

It turns out that the variations of the plasma properties inside the bubbles can exactly reproduce the observations, namely the smooth surface and the sharp edges of the bubbles. The other models cannot explain this.

OSB: If you are correct what does this tell us about our galaxy/galaxy formation in general?
PM: An important question is of course where does this shock front come from? Looking at other galaxies we see similar bubbles being produced by jets powered from the central black hole. This is certainly a possibility for our own Galaxy.

In fact it is rather peculiar that the black hole at the centre of the Milky Way is so quiet - it now appears that this may just be a transient phase.

This picture is further supported by numerical simulations which have shown that a jet shooting out from the centre above and below the galactic plane can easily produce structures of the size and shape of the Fermi bubbles.

OSB: How could your ideas be tested?
SS: Our model for the gamma-ray emission predicts a unique energy-dependence: at lower energies, the surface of the bubbles is very smooth but at higher energies, the bubble inside should become fainter while only the edges stay bright. The energies at which this happens are beyond the reach of the Fermi satellite but with data from the forthcoming Cherenkov Telescope Array this shell-like structure should become observable. 

Whether you are playing poker or haggling over a deal you might think that you can hide your true emotions.

But telltale signs can reveal that you are concealing something, and now researchers at Oxford University and Oulu University are developing software that can recognise these ‘micro-expressions’ - which could be bad news for liars.

‘Micro-expressions are very rapid facial expressions, lasting between a twenty-fifth and a third of a second, that reveal emotions people try to hide,’ Tomas Pfister of Oxford University’s Department of Engineering Science tells me.

‘They can be used for lie detection and are actively used by trained officials at US airports to detect suspicious behaviour.

‘For example, a terrorist trying to conceal a plan to commit suicide would very likely show a very short expression of intense anguish. Similarly, a business negotiator who has been proposed a suitable price for a big deal would likely show a happy micro-expression.’

Tomas is leading efforts to create software that can automatically detect these micro-expressions - something he says is particularly attractive because humans are not very good at accurately spotting them.

He explains that two characteristics of micro-expressions make them particularly challenging for a computer to recognise:

Firstly, they are involuntary: ‘How can we get human training data for our algorithm when the expressions are involuntary?’ he comments. ‘We cannot rely on actors as they cannot act out involuntary expressions.’

The second big problem is that they occur for only a fraction of a second: this means that, with normal speed cameras, they will only appear in a very limited number of frames, leaving only a small amount of data for a computer to go on.

The researchers looked to tackle the first problem by an experiment in which those taking part were induced to suppress their emotions.

‘Subjects were recorded watching 16 emotion-eliciting film clips while asked to attempt to suppress their facial expressions,’ Tomas explains.

‘They were told that experimenters are watching their face and that if their facial expression leaks and the experimenter guesses the clip they are  watching correctly, they will be asked to fill in a dull 500-question survey. This induced 77 micro-expressions in 6 (now 21) subjects.’

To overcome the problem of the limited number of frames the researchers used a temporal interpolation method where each micro-expression is interpolated - essentially ‘gaps’ in the data are filled in with existing data - across a larger number of frames. This makes it possible to detect micro-expressions even with a standard camera.

Early results from the work are promising, with the automated method able to detect micro-expressions better than a human, Tomas comments:

‘The human detection accuracies reported in literature are significantly lower than our 79% accuracy. We are currently running human micro-expression recognition experiments on our data to get a directly comparable human accuracy.’

But the writing may not be on the wall for liars and con-artists just yet.

Automated recognition of micro-expressions is one thing, Tomas says, but detecting deception, and uncovering the truth, is considerably harder:

Micro-expressions should be treated only as clues that a person is hiding something, not as conclusive evidence for deception. They cannot indicate what that person is hiding or why they are attempting to conceal it.

Tomas adds: ‘That said, our initial experiments do indicate that our approach can distinguish deceptive from truthful micro-expressions, but we will need to conduct further experiments to confirm this.’

For many scientists writing about science either in their spare time or as a career can seem attractive: but what does it take to be a successful science writer?

I caught up with Penny Sarchet, a doctoral student at Oxford University’s Department of Plant Sciences, who has managed to combine her studies with writing science articles for, among others, The Guardian, The Sunday Telegraph, and New Scientist.

She recently won the Wellcome Trust/Guardian & Observer Science Writing Prize [read her article in The Observer]: I asked her about winning, her favourite stories, and what it was like to write for our very own OxSciBlog…

OxSciBlog: How did you first become interested in science writing?
Penny Sarchet: When I started my DPhil, I was surprised to find that I missed writing undergraduate tutorial essays! I really enjoyed being given a topic and being told to go off and write something good about it.

Research scientists do read and write a lot but you mainly have to focus on your (rather narrow) field and write in a very specific, scientific way. Science writing allowed me to continue my wider interest in science and gave me an outlet for writing in a more accessible, generalist way.

OSB: What did you get out of writing for OxSciBlog?
PS: I wrote articles about research in my own department (Plant Sciences). It was a great excuse to sit down with different professors I admire and ask them lots of questions! There’s some fantastic science going on in Oxford and you feel honoured when someone takes the time to explain some of it to you.

I covered fighting world hunger through crop improvement and the modern face of the historic University Herbaria, and I enjoyed helping to place a spotlight on some of the exciting work that’s being done on these.

OSB: What are your highlights from the work you’ve done so far?
PS: I’ve just won the inaugural Wellcome Trust/Guardian & Observer Science Writing Prize (professional scientists’ category), so that’s the definite highlight. Prior to that, I was really pleased to get a news story about the invasion of harlequin ladybirds into The Sunday Telegraph because I’ve been going on to everybody I know about the plight of British ladybirds for years!

Interviewing the artist Angela Palmer, who created the Ghost Forest (currently outside Oxford’s Museum of Natural History) for the Oxford magazine Phenotype was also a lot of fun too – her determination to disobey everyone who told her she couldn’t bring a collection of gigantic Ghanaian trees whole into the UK made a really great story.

OSB: What led to the choice of subject for your WT entry?
PS: I report on recent science findings for the alumnae magazine Oxford Today. I was looking for stories for last Trinity’s edition and I came across the work of Professor Irene Tracey.

She’d been using MRI scanning to look at how negative expectations can completely reduce the effectiveness of pain killers through something called the nocebo effect. I’d never heard of this flip-side of the placebo effect before.

Reading more about it, I saw that it has so many implications for health and medicine – the fact that doctor-patient trust and the power of suggestion could potentially be fatal really interested me, so I began looking for an excuse to write about it. Then I heard about the new Wellcome Trust/Guardian & Observer Science Writing Prize.

OSB: What was it like to hear you’d won?
PS: Fantastic and unexpected! I’d spent the day at a workshop at The Guardian with the other 29 shortlisted writers and they were all such interesting people with imaginative topics, so I really didn’t think I’d win.

When Dara O’Briain read out my title I had to pause to make sure in my head that it really was mine! I really enjoyed meeting so many other science journalism/writing/blogging enthusiasts and the message of the awards ceremony – that science journalism has never been so important or in-demand – was very up-beat and encouraging.

OSB: What advice would you give any budding science writers?
PS: Give it a go! You don’t know if you’re any good or if you'll enjoy it until you try. There are lots of opportunities in Oxford for students and staff to cut their teeth. It’s easy now with the internet – anyone can set up a blog and have a try.

Scientists keen to understand and preserve global biodiversity have been quietly going about a mammoth task: indexing the world’s known species.

So far the Catalogue of Life has indexed over 1,368,009 species and the latest edition features a database from Jeya Kathirithamby of Oxford University’s Department of Zoology detailing Strepsiptera, a strange order of parasitic insect.

Strepsiptera are endoparasites – they live inside their host – with almost all females spending their entire lives inside the body of other insects and males emerging as free-living adults to mate before they die, just five or six hours later.

‘The females are totally endoparasitic for their entire life history (except in one family) and all that is visible of an adult female is an extruded cephalothorax,’ Jeya tells me. ‘The female is nothing more than a “bag of eggs”, having lost all structures such as eyes, antennae, mouthparts, legs, wings and external genitalia any other insect would possess.

‘This dramatic difference between male and female makes Strepsiptera interesting model organisms for studying such aspects as mating and reproduction.’

Jeya is a world authority on these parasites where males and females can have such different lives that they even choose entirely different hosts:

‘There is a family where the males parasitize ants and the females parasitize grasshoppers, crickets or mantids. Due to the extreme sexual dimorphism and dual hosts, the sexes could not be matched until recently. We have achieved this using molecular data.’ 

Surprisingly, although Strepsiptera can infect and live inside the host insect for almost its entire life, the host seems unaffected and can even have its lifespan extended.

‘Strepsiptera have adapted to the life cycle of whatever host they parasitize,’ Jeya explains. ‘The comparison of the strepsipteran life cycle to the life cycles of the various hosts they parasitize is fascinating: For example the strepsipteran life cycle in a host which is a eusocial wasp is different to that of a host which is a solitary wasp and is different to that of a host which is an ant.’

Despite its unusual lifestyle this order of insect is far more than a curiosity: there are thought to be more than 600 species, with genetics revealing that individuals that look identical are in fact different species.

A recent molecular study carried out by Jeya and her collaborators found that a monotypic species in the southern states of the USA, Mesoamerica and the Neotropics revealed as many as ten cryptic species – animals which appear identical but are genetically distinct.

‘The global Strepsiptera database in the Catalogue of Life has host records and geographical distribution. These will be linked to the database of the hosts and to GenBank data. In our molecular studies, we sequence the hosts as well in order to check for contamination,’ Jeya tells me.

‘Like most Strepsiptera we find in the field the hosts are also often new to science. Here again there will be links to molecular data of the hosts. Strepsiptera parasitize seven orders of Insecta so this will be a substantial contribution.’ 

According to Jeya, Strepsiptera could include so many examples of cryptic speciation because of the different hosts they parasitize or their geographical distribution.

She comments that understanding the factors involved could prove very helpful in the study of a wide range of insects:

‘For instance, we are working on the phylogeny of crickets from Central America because we collected a large sample of crickets while looking for strepsipterans. Many of these crickets are new to science and at present there is no comprehensive data for crickets of Central America.

‘Both the molecular data and the geographical distribution of the cricket hosts will be linked to the database. This information will be invaluable for future researchers. Similarly, we are working on another little known host group in another area.’   

Dr Jeya Kathirithamby is based at Oxford University’s Department of Zoology.