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SPHERE opens its 'all-seeing' eye

SPHERE images the dust ring around HR 4796A (Courtesy: ESO/J-L Beuzit et al./SPHERE Consortium) — The dust ring around HR 4796A. (Courtesy: ESO/J-L Beuzit *et al.*/SPHERE Consortium)

By Tushna Commissariat

While the fiery shades of the image above may seem familiar to fans of the Lord of the Rings movie franchise, pictured above in exquisite clarity is a ring of dust that surrounds the near-by star HR 4796A. The young, hot star – located a scant 240 light-years from Earth – has been of significant interest to astronomers since the circumstellar ring of debris was detected, thanks to an excess of infrared emissions from the star. While there have been many other images of the HR 4796A system, this particular image has been obtained by the new Spectro-Polarimetric High-contrast Exoplanet REsearch instrument (SPHERE), which was installed in May this year on the European Southern Observatory’s Very Large Telescope (VLT) at the Paranal Observatory in Chile. Thanks to the instrument, not only is the dust-ring clearly outlined, but the glare of the bright star at the centre of the picture has been supressed. This has provided a much clearer view of the whole system, which researchers think also harbours an exoplanet or two.

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The future is flexible

Sometimes, it feels as if the future has already arrived. That is the case with electronics that can bend and flex, leading to applications such as sensors that can conform to clothing and skin. This short film takes you inside the headquarters of one of the most exciting companies in this emerging technology area: a spin-off firm called MC10 based in Cambridge, Massachusetts.

One of the company co-founders is John Rogers of the University of Illinois at Urbana-Champaign, who is a pioneer in the field of flexible electronics. In the film, Rogers talks about how his interest in the field emerged from the observation that all known forms of biology are soft, elastic and curvilinear, whereas existing forms of electronics are rigid, planar and brittle. “As a result, if you want to integrate electronics with biology – with human skin or tissue – you have severe challenges in a mechanics mismatch and a geometrical form mismatch,” he says.

Rogers describes how MC10 has overcome this limitation by developing a printing process that allows electronic devices to be built on rigid wafers before being removed in thin formats and then printed onto rubber substrates. This innovation enables the company to develop professional and consumer products based on integrated electronics that can flex and reshape in a range of different environments.

The film looks at one of the company’s most high-profile products: the Reebok CHECKLIGHT, which was developed in partnership with the consumer sports giant that also has it global headquarters in Massachusetts. It is essentially a type of skullcap that combines an accelerometer with a gyroscope to measure the magnitude and danger of impacts to the head. One of the problems, particularly with sports such as American football, is that there tends to be something of a hero culture whereby players will respond to head collisions by saying “I’m fine, coach”, even if they are not. The CHECKLIGHT is designed to provide an objective assessment of the impact to the head in that scenario.

Also featuring in the film is Benjamin Schlatka, MC10’s vice-president of business development. He talks about how the company came into existence in 2008 having begun as research in a science laboratory. “[John Rogers] had a connection with an investor, an entrepreneur, here in the Boston area that was a connector to two of the other co-founders.”

Plans unveiled for world’s first X-ray frequency comb

A design for what would be the world’s first X-ray frequency comb has been unveiled by physicists in Germany. The team believes that its comb – which would be used to measure the frequencies of X-rays – can be built using existing technologies. A working device could be used to make fundamental measurements in atomic physics with much greater precision than is possible today. The design could even be extended to produce gamma-ray combs, say the physicists.

Conventional frequency combs are short laser pulses comprising light at a number of well-defined frequencies. When plotted as intensity versus frequency, the light is represented by a series of sharp, equally spaced peaks that together resemble the teeth of a comb. Combs are used as a ruler to measure with great accuracy an unknown frequency relative to a precisely defined reference frequency, such as an atomic clock. Combs can therefore detect tiny changes in the frequency of a light signal that is associated with a physical phenomenon. For example, the gravitational tug of an exoplanet causes a periodic change in the Doppler shift of the light from its companion star’s light.

Combs working at optical frequencies were first developed in the 1990s by John Hall at the JILA Lab in Boulder, Colorado, and Theodor Hänsch at Ludwig Maximilians University in Munich, Germany, – who shared a Nobel prize for their efforts. Since then, physicists have been extremely keen to produce combs at higher frequencies. Ultraviolet combs have been produced by high-harmonic generation, in which a lower-frequency laser excites electrons in a gas and causes them to accelerate and emit light at higher harmonics of the original laser frequency. However, the intensity of successive harmonics decreases, so generating pulses in the X-ray region would require an impracticably powerful driving laser.

Subtler approach

Now, Stefano Cavaletto and colleagues at the Max Planck Institute for Nuclear Physics in Heidelberg have come up with a more subtle approach. They propose using three energy levels of the Be²⁺ ion to create an X-ray comb. The upper excited state lies 123.7 eV above the ground state – a gap that corresponds to low-energy or “soft” X-rays. This state is unstable, and so electrons decay rapidly back to the ground state. The third, metastable state lies just below the main excited state. Electrons in this state remain excited much longer. The group’s idea is to use an X-ray free-electron laser to pump electrons from the bottom state to the top state. Another applied laser pulse then leads the excited electrons to the metastable state, where they remain. If an optical frequency comb irradiates the ion, then with every pulse, some of the photons are promoted from the metastable state to the unstable state, before decaying almost immediately to the ground state with the emission of an X-ray pulse. This produces a series of X-ray pulses modulated at the same rate as the original optical pulses, forming an X-ray frequency comb.

Such a device could have numerous applications in fundamental physics. For example, it would become possible to measure precise values of the transition energies of the inner-shell electrons in highly charged ions. This would allow for stringent checks on the predictions of quantum electrodynamics and whether the fine-structure constant varies over time. “There are papers predicting that such measurements may be more sensitive at higher energies,” explains Cavaletto.

Even higher frequencies

Some of the co-authors of the paper are experimentalists, and Cavaletto says that they are confident it is possible to build the device with available equipment now. He also says that the basic principle could be extended to even higher frequencies. Indeed, gamma-ray frequency combs could be possible, although suitable three-level systems would need to be identified and a free-electron laser would need to be developed that could excite the initial transition.

Jun Ye, who heads the team at JILA that produced the first extreme-ultraviolet frequency comb, is impressed. “This is the first time that a feasible idea for the generation of frequency combs in the X-ray region has been proposed,” he says. “Such work will open up completely new scientific fields and fulfil old dreams. I am very excited about this approach.”

The research is published in Nature Photonics.

For a simple explanation of how a frequency comb works, watch this video of Paul Williams from NIST in Boulder, Colorado.

Functional MRI tracks neurotransmitters

Researchers in the US have for the first time used MRI to follow the dynamics of neurotransmitters with molecular precision. They have demonstrated the technique on dopamine, a neurotransmitter that represents processes of reward and motivation in the brain.

Neurotransmitters are the chemicals released at the end of nerve fibres to communicate signals to other nerve fibres in the vicinity. An understanding of their dynamics is important for a more general understanding of brain function, yet they are hard to study. In the past, scientists have resorted to PET, an imaging technique that relies on a radioactive tracer being inserted into the body so that its path can be monitored by emitted gamma rays. But PET can only supply images that are spatially accurate to within a few millimetres and temporally accurate to within a few minutes.

Contrasting agents

Functional MRI (fMRI) could be more precise. As in standard MRI, fMRI involves the use of a fixed magnetic field to align the spins of protons inside the water molecules of tissue. After radio waves have deflected these spins, their relaxation back to alignment is timed with a radio receiver coil, and this time reveals the tissue’s composition. The difference with fMRI is that paramagnetic molecules known as “contrast agents” interact with some of the water molecules, thereby changing their brightness in scans. Haemoglobin in blood is a natural example: on its own, it acts as a contrast agent, but when it is bound to oxygen, its effect is diminished. In this way, scientists can use fMRI to study the circulation of oxygenated and deoxygenated blood.

Now, medical engineer Alan Jasanoff and colleagues at the Massachusetts Institute of Technology (MIT) in the US have experimented with another contrast agent – the paramagnetic haem protein BM3h. Instead of turning off when bound to oxygen, BM3h turns off when bound to dopamine, and can therefore be used with fMRI to sense the progression of the neurotransmitter between nerve fibres. The team claims that this form of imaging is an order of magnitude more accurate than PET. “Our study is the first to use MRI to study the dynamics of neurotransmitter release and signalling,” says Jasanoff.

The MIT group tested its technique on live rats by injecting BM3h into a region of the brain known as the ventral striatum, which emits dopamine, and electrically stimulating the medial forebrain bundle (a part of the reward system). Each dopamine stimulation lasted 16 s and the researchers took an MR image every 8 s, allowing them to track how dopamine levels changed as the neurotransmitter was released from cells and then disappeared.

Dopamine dynamics

“Neurotransmitters play distinct functional roles, which we can study by imaging their dynamics,” says Jasanoff. “For instance, dopamine is important for the brain’s ‘internal representation’ of reward and motivation, and if we want to figure out how dopamine works to achieve this, we should learn where and when dopamine concentrations are changing in the brain.”

The researchers found that an area known as the nucleus accumbens core (NAcC), which is known to receive dopamine from an area of the brain, showed the highest levels of dopamine release, according to the fMRI scan. They also found that dopamine was released in neighbouring regions such as the ventral pallidum, which regulates motivation and emotions, and parts of the thalamus, which relays sensory and motor signals in the brain.

Jasanoff and colleagues also believe that the technique could help in studies of Parkinson’s disease, which is caused through death of dopamine-generating cells. But Jasanoff is not going to stop with the imaging of dopamine by fMRI. “We are also developing and applying molecular sensors for MRI-based mapping of many other aspects of neural activity,” he says.

The research is published in Science.

This article first appeared on medicalphysicsweb.org.

Physicists lock in on proton’s magnetic moment

Illustration of a proton in a Penning trap — Illustration showing a proton (red) confined by magnetic-field lines (green) running down the centre of a Penning trap (yellow). (Courtesy: G Schneider, University of Mainz)

The most precise measurement ever of the proton’s magnetic moment has been made by an international group of physicists. The new result – combined with a similar measurement planned for the proton’s doppelganger, the antiproton – could help explain one of the deepest mysteries of physics – why the universe’s matter seems to vastly outweigh its antimatter.

Every fundamental particle has a nearly identical antiparticle with opposite electric charge. Physicists’ leading theories indicate that particles and their antiparticles were created in equal amounts during the Big Bang and should have annihilated each other long ago. But the universe is full of matter and lacks antimatter, suggesting that an undetected difference might exist between the two.

Minute differences

One possible clue about the difference could lie in tiny discrepancies between the magnetic moments of particles and their corresponding antiparticles. Any difference would be the first-known violation of a fundamental principle that physicists call charge–parity–time (CPT) symmetry. In 2013 researchers working at the Antihydrogen trap (ATRAP) experiment at CERN set the record for the most precise comparison between the magnetic moments of the proton and the antiproton, but the scientists found no difference between the two.

Now, Klaus Blaum, of the Max Planck Institute for Nuclear Physics in Germany, and colleagues are seeking an even more stringent CPT symmetry test. They used a cylindrical device called a Penning trap to confine a single proton using magnetic and electric fields. The trap’s magnetic field causes the proton to circle the cylinder’s axis at a rate known as its cyclotron frequency. The field also makes the direction of the particle’s spin precess like a spinning top, but with a different frequency. From the ratio of these two frequencies, scientists can calculate the particle’s magnetic moment.

Double trap

Measuring the cyclotron frequency is relatively easy, but the precession frequency is harder to pin down. For this reason, Blaum’s group built on a 2008 technique developed by another group of researchers to precisely measure the magnetic moment of the electron. In that work, the researchers applied a second magnetic field that caused the precessing electron to change how it oscillates along the cylinder’s axis. The oscillation frequency then changes slightly again when the particle’s spin flips from pointing up to pointing down, so by forcing a spin flip and measuring the resulting frequency shift, the scientists were able to determine the electron’s precession frequency and thus its magnetic moment.

Photograph of a Penning trap — Researchers have used this cylindrical device, known as a Penning trap, to confine a single proton for more than one year. (Courtesy: C Rodegheri, Max Planck Institute for Nuclear Physics)

To apply this technique to the proton’s much smaller magnetic moment, Blaum’s group developed what it calls a “double Penning trap”. In one trap the researchers determined the proton’s spin state, using a technique they reported in 2011. They then shuttled the proton to a second trap, where they measured the particle’s cyclotron and oscillation frequencies. The researchers repeated the process thousands of times over four months, eventually determining the proton’s magnetic moment to a precision of just over three parts in a billion. This figure is around 760 times more precise than what the ATRAP group achieved in 2012.

“I congratulate this team for showing it could do [this measurement] with the proton,” says Gerald Gabrielse, at Harvard University, who is the ATRAP spokesperson and was also involved in the 2008 research. But he notes that without the antiproton measurement, physicists are no closer to understanding matter’s dominance.

Blaum says his team will soon take that measurement. Team member Stefan Ulmer of RIKEN, a research institution in Tokyo, has already installed a double Penning trap on CERN’s Antiproton Decelerator, which will begin producing particles this summer. Within a year after that, Blaum thinks he and his colleagues should know whether the antiproton’s magnetic moment differs from that of the proton at the precision they have achieved. But Blaum adds that as his “trust in CPT is very high”, he is not betting on a discrepancy.

The research is published in Nature.

Cosmic blunders that have held back science

Big enough already: portrait of Edward Pickering by Sarah Gooll Putnam. (Courtesy: Harvard University Portrait Collection)

By Hamish Johnston

Can you name 10 blunders that have held back the progress of modern astronomy? Avi Loeb of Harvard University can, and he lists them in an essay entitled “On the benefits of promoting diversity of ideas”, which is posted on the arXiv preprint server.

Loeb argues that a common flaw of astronomers is to believe that they know the truth even when data are scarce. This, he argues, “occasionally leads to major blunders by which the scientific community makes the wrong strategic decision in its research plans, causing unnecessary delays in finding the truth”.

The first example he gives is the 1909 pronouncement by Edward Pickering, director of the Harvard College Observatory, that telescopes had reached their optimal size and that there was no point trying to make them any bigger.

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Adventures in Antarctica

It’s the depths of winter in Antarctica right now, but in the new issue of Physics World magazine, there’s a chance to feast your eyes on some stunning images of scientific research in the White Continent, taken a few months ago by photojournalist Enrico Sacchetti.

Sacchetti’s photographs are amazing and in the article he explains his experiences of travelling to Antarctica and taking pictures in what is one of the world’s harshest environments.

“As soon as I stepped off the C-130 [plane], the alien nature of Antarctica was truly jolting…Almost completely absent of atmospheric pollution, the air was crystal clear,” Sacchetti writes.

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Between the lines

Illustration of maths — Mathematical block: Michael Faraday became one of the 19th century’s greatest scientists despite his lack of mathematical nous. (Courtesy: iStock/Vasiliki Varvaki)

Mathematical or not

Read this and let it sink in for a moment: Michael Faraday could barely do basic algebra. Advanced mathematics was a closed book to the discoverer of electromagnetic induction and, as Nancy Forbes and Basil Mahon put it in their book Faraday, Maxwell and the Electromagnetic Field, “Ampère’s equations might as well have been written in Egyptian hieroglyphics.” This fact makes his rise to the top of 19th-century physics all the more remarkable – but then, Faraday was a remarkable man. Born to a poor family and sent out to work at 13, he supplemented his meagre formal education with diligent private study. After becoming Humphrey Davy’s assistant at London’s Royal Institution, he rose to be the director of its laboratory. He also taught himself the art of public speaking, giving scientific lectures and demonstrations to the people who flocked to hear him. Given these successes, it is actually a little surprising that he never managed to learn his way around trigonometry or calculus. In any case, Forbes and Mahon argue that Faraday’s lack of mathematical training “led him to derive his theories entirely from experimental observation…[and] gave him a deep-seated intuition into electromagnetic phenomena”. It’s a persuasive argument, but even so, Faraday clearly felt the deficit all his life. In one of the book’s most touching passages, the authors describe Faraday’s joy at receiving a paper entitled “On Faraday’s lines of force”, in which a young James Clerk Maxwell began to put the older scientist’s ideas on firmer mathematical ground. In a cordial reply to Maxwell, Faraday wrote, “I was at first almost frightened when I saw the mathematical force made to bear on the subject, and then wondered to see that the subject stood it so well.” This is not a complete biography of either Faraday or Maxwell, but it is a good introduction to both, with plenty of insights into their characters.

2014 Prometheus Books $25.95hb 300pp

Finding the Higgs

Particle physicists are sometimes accused of being arrogant. When they write sentences like “Away from the LHC, other physics was going on,” it’s not hard to see why. To be fair to Jon Butterworth, who unloads that particular gem halfway through his book Smashing Physics, it’s clearly meant as a comic understatement. And to be fair to particle physicists generally – well, they’ve had a lot to be arrogant about recently, so why not enjoy it with them? Smashing Physics tells the story of the discovery of the Higgs boson at the aforementioned LHC (Large Hadron Collider) from the perspective of Butterworth, a physicist at University College London and a leading member of the LHC’s ATLAS collaboration. Butterworth has worked on LHC physics for a little over a decade, but in his words, this makes him “a bit of a Johnny-come-lately by experiment standards”, since the LHC was approved in 1997 and its design was discussed officially back in 1984. What the reader gets, therefore, is a history of LHC science that skews heavily towards the present day, with a particular focus on the 36 months between the collider’s late-2009 restart and the July 2012 announcement that the Higgs boson had, at last, been discovered. Like the Higgs hunt itself, Butterworth’s story comes with plenty of detours. Some of these detours concern basic physics. Others cover the politics of working on a large collaboration, battles over UK science funding and, in one case, a memorably surreal night out in Hamburg. It’s a lively account that gets somewhat more insider-ish as it goes along, but readers who are willing to do a bit of work to understand the material will find this a smashing journey.

2014 Headline £20.00hb 304pp

Bombs, guns and trebuchets

Two years after the end of the Second World War, J Robert Oppenheimer told a lecture-room audience that “the physicists have known sin” for their work in developing the atomic bombs dropped on Hiroshima and Nagasaki. In fact, the historical connections between physics and war are very much older. In The Physics of War, retired physicist and science writer Barry Parker sets out to explore these links, deftly interspersing physics explanations with accounts of battles ancient and modern. Unfortunately, reading it is a bit like drinking artificially flavoured cola: fine at first, but with a sour aftertaste. One problem is that the book is highly western-oriented, as shown by the author’s sweeping assertion that “the world” entered the Dark Ages after the fall of Rome in 476 AD and “few advances in science were made” during the 1000 years that followed. This may come as a surprise to scientists (and historians) in, say, China, which is pretty well ignored throughout. But there are actual errors here as well as omissions. The trebuchet was not, as Parker claims, “invented by the Romans”. The pioneering marine engineer and submariner of the American Civil War was called Hunley, not Hurley, and if Archimedes had really been born in 87 BCE, as the book states, that would be impressive, since he died around 212. By the 20th century, the book is on firmer ground. But by then, it’s a little late.

2014 Prometheus Books £22.99hb 340pp

Particle man meets universe man

When particle physicist Jon Butterworth and cosmologist Pedro Ferreira took the stage last night at the Bristol Festival of Ideas, they did so as representatives of the two pillars of modern physics. Butterworth, a leading member of the ATLAS collaboration at CERN’s Large Hadron Collider, spoke about the discovery of the Higgs boson and the effort to understand the nature of matter on the quantum level. Ferreira, a theorist at the University of Oxford, focused on Einstein’s general theory of relativity, which describes the behaviour of colossal objects such as galaxies and black holes.

The equations of quantum mechanics and general relativity are famously incompatible, but far from starting a Harry Hill-style confrontation (“FIIIIGHT!”), the advocates of the two theories shared the stage amiably, fielding questions from audience members and talking about their respective new books (Smashing Physics for Butterworth, The Perfect Theory for Ferreira). You can hear Ferreira and Butterworth’s responses to some common (and not-so-common) questions in the clips below.

Universe man

Particle man

As the event’s moderator, I got to chat with both speakers beforehand, and in the process I learned something startling. I’d never met Butterworth before, but back in 2009, I reviewed a series of short documentary films called Colliding Particles that featured Butterworth and some of his students. I liked the films and thought they gave viewers a good idea of what it was like to work at CERN, but there was, I noted, “relatively little physics” in them.

Butterworth decided this was a fair point, and he wrote his first ever blog post in response. (Update: He’s also written a post about the Festival of Ideas event.) Less than a year later, his new-found talent as a blogger earned his Life and Physics blog a spot on the Guardian‘s network, and the book deal followed from that. So in a rather roundabout way, my little review was the catalyst for an entire book – one in which, Butterworth says, he tried to balance the gossipy, my-life-as-a-scientist stuff with an in-depth look at the physics of hunting the Higgs boson.

A day in the life of an astronaut, Hawking’s football conclusions, politics and science and more

Image from Tim Dodd's Everyday Astronaut photo series — "Good morning world". (Courtesy: Tim Dodd)

For most of us, the life of an astronaut is one of excitement and adventure. Indeed, the mere thought of being a “real live astronaut” brings out the gleeful inner child in many, and photographer Tim Dodd is much the same. After purchasing a Russian high-altitude space suit from an online auction website, Dodd put together a series of photographs titled “A day in the life of Everyday Astronaut”, my favourite of which you can see above. Do take a look at the rest of the excellent series on Dodd’s website and follow him on Instagram for even more of the same.

In other news, famed physicist Stephen Hawking has spent his considerable genius on developing a formula that could help the English football team win this year’s FIFA World Cup. This surprising turn of events took place when Irish bookmaker Paddy Power asked the scientist to look at England's past World Cup performances and draw some conclusions about what conditions were most favourable for an English win. Take a look at this Guardian article to find out what Hawking’s conclusions were…and then hope that the kick-off for each game is at precisely 3 p.m. BST.

Talking of well-known physicists, Paul Frampton, the now infamous particle physicist from the University of North Carolina who was arrested at Buenos Aires airport in 2012 for drug smuggling, has been fired from his tenured university post for “for misconduct and neglect of duty”. You can read about why he was still employed while languishing in prison in Argentina for nearly two years in this article published on the New Observer website. Do you think this too will feature in the film about his incredible story that is in the pipeline?

Readers based in the UK might be interested in this New Scientist article that looks into the impact on science that anti-EU parties such as the UK Independence Party (UKIP) could have after they were elected in large numbers to the European Parliament. Author Michael Brooks looks at the realities of losing funding from the European Research Council, collapsed international collaborations and an all-around loss of “international competitiveness”.

And in other weekend reading, take a look at this Yale university course that brings together the “introductory principles in classical and modern physics and in classical and modern dance”, read about the sensational gamma-ray burst that wasn’t and take this Guardian quiz of classic sci-fi book covers.

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SPHERE opens its 'all-seeing' eye

The future is flexible