I have only ever reviewed a couple of manuscripts in what was my brief career as a research scientist.
I remember finding it quite exciting at first, as well as being honoured to be selected by a publishing house to be able to review articles submitted by my peers for publication.
However, being a busy researcher, running experiments and writing papers, by the time the third e-mail reminder landed in my inbox asking me to finish the review as quickly as possible, I could see how researchers get fed up of reviewing articles, sometimes as many as 20 per year.
Peer review, of course, has a serious and important role in science. Still, I was rather surprised to see that 86% of respondents to a new survey on peer-review practises say they actually enjoy reviewing.
Over 4000 researchers responded to a survey carried out by Sense About Science – a UK-based charity that promotes the public understanding of science.
In what is the largest international survey of authors and reviewers to date, Sense About Science has now released its preliminary findings from the 2009 survey.
Although the survey does not seem to reveal how many papers a researcher reviews per year, it does find that, on average, reviewers turn down two papers every year.
According to the survey, the biggest benefit of peer review is that it makes researchers feel like part of the community, with 90% of respondents saying this is why they do it. Only 16%, however, say that reviewing increases their chances of having future papers accepted.
There is the argument that due to the “publish or perish” ethos in science, there are not enough researchers to peer review the increasing number of articles being submitted to journals.
However, according to the survey only 20% of respondents thought that peer review is unsustainable because of too few willing reviewers.
There is also the tricky question whether peer review stops plagiarism and fraud. While 81% say that peer review should detect plagiarism and 79% say that it should prevent fraud, only around 35% say it is capable of doing both.
And lastly, 41% of researchers say they would like to be paid to peer review, but not at the cost of the author. More than half of respondents thought that a payment in kind such as a subscriptions would make the more likely to review.
Researchers in Germany have created a new type of fastener system made from steel that may be useful in a range of settings, including hospitals and the aviation industry. Borrowing its design from nature, the new material comprises a series of hooks in the shape of birds’ heads that feed into a series of tiny loops along a perforated strip.
Velcro was invented more than 60 years ago by the Swiss inventor George de Mestral, who drew inspiration from the difficulty he experienced when removing burrs from the fur of his dog. The product name originates from the French for velvet (velours) and hook (crochet) on account of the underlying mechanism – a piece of fabric covered in tiny hooks fastens to a second piece of fabric covered in tiny hairy loops.
The real beauty of this “wonder material” is that it can seal with a relatively tight grip but still be released with minimal effort. For this reason it has found a plethora of applications from a shoe-lace substitute to bandages in hospitals. It is even used in some industrial applications to hold machinery together. Although originally made using cotton, hook-and-loop fasteners are now typically fabricated using nylon and polyester on account of their strong grip and resistance to wear and tear.
Sticky situation
The trouble, however, with these fasteners is that their gripping mechanism tends to break down when exposed to harsh conditions such as high temperatures and aggressive cleaning chemicals. This limitation leads to problems in industrial and applications.
Now, a research team at the Technical University of Munich, working in conjunction with industrial firms based in Germany, may have found a solution to this problem. They have created a new hook-and-loop fastener using steel, chosen for its high resistance to mechanical loads and chemical corrosion. Steel is also highly ductile, meaning that it can deform significantly under high stresses without fracturing and breaking the grip.
In developing the fastener, which is dubbed “Metaklett“, meaning “metal burr”, Josef Mair and his colleagues tested a range of different hook designs. After combining laboratory testing with computer simulations, the researchers settled on two specific designs, both of which are resistant to chemicals and remain fastened up to 800 °C.
Follow the birds
The first hook mechanism is based on the shape of a flamingo, which provides a more stable locking mechanism than the hooks in conventional fasteners. This type of Metaklett is designed for its pure strength because, depending on the direction of the applied force, the fastener can withstand a load of up to 35 tonnes per square metre.
The second type of hook is called an “Entenkopf”, because it resembles a “duck’s head”, and this design is closer to synthetic Velcro. While this design cannot support the same sort of load, it has the advantage of flexibility because it can remain fastened while subjected to stresses from a variety of directions. Mair and his team are also working on a third design – the “hybrid” model – which combines the strength of the flamingo with the flexibility of the duck.
Since the beginning of this project, the researchers have been working with industry with the aim of creating bespoke metal fasteners for a range of applications. “I can imagine Metaklett being used in hospitals – for example, as a means of fastening curtains that doesn’t get damaged when exposed to hospital cleaning,” said Mair.
The automotive and aviation industries may also benefit from the new advance. “Things can get very hot in the automotive sector. A car parked in direct sunlight can reach temperatures of 80 °C, and temperatures of several hundred degrees can arise around the exhaust manifold,” said Mair. The researcher told physicsworld.com that he can envisage his new metal fastener being used both as a shield covering exhaust pipes and as a means of holding panels together in planes.
a) the mass of a body with a de Broglie wavelength of 6.626069311 x 10^-34 m at a velocity of 1 m/s
b) a mass of a body at rest such that Planck’s constant h is 6.626069311 x 10^-34 Js
c) a mass of exactly 5.0184512725 x 10^25 unbound carbon-12 atoms at rest in their ground state
d) the mass of a lump of platinum-iridium sitting under three vacuum jars in a French laboratory
Readers with an interest in metrology will know that the answer is d) — and anyone who didn’t know it could probably have guessed from the photo. But why is the kilogram, alone of all SI units, defined by something so un-fundamental as a lump of metal?
The difficulty, as Bryan Kibble explained this afternoon in a talk at the QuAMP conference in Leeds, is that several of the alternatives have problems of their own. Options a) and b) both rely on pinning down a value for Planck’s constant, and thus might seem like the best way to go; indeed, one of them may actually become the new SI definition, perhaps as early as 2011. However, Kibble argued, both options are somewhat circular, swapping uncertainty in the kilogram for uncertainty in other Planck-derived units, and there’s not really any new science involved in them.
A definition in terms of carbon-12 atoms — or indeed, any kind of atoms — would be more satisfying, Kibble says, but as efforts like the Avogadro project at the UK’s National Physical Laboratory have shown, counting atoms isn’t a trivial task.
Nobody offered any solutions during the question period after the talk, but we did manage to pin down one thing: any fluctuations in fundamental constants (like the fine structure constant, for example) will not affect the kilogram problem — at least not for around 1000 years. So that’s all right then.
How long does an electron take to tunnel out of an atom exposed to a strong laser field?
Given the somewhat esoteric nature of the question, you might assume that the answer would lie firmly in the realm of theory. But Ursula Keller, whose talk opened this year’s International Conference on Quantum, Atomic, Molecular and Plasma Physics (otherwise known as QuAMP, is an experimentalist, and she and her group at ETH Zurich have made some interesting progress towards pinning down just how long this fundamental quantum-mechanical process takes.
Using a technique called attosecond angular streaking, Keller’s team found an upper bound for the tunneling time of 34 attoseconds. That’s quick — in fact, Keller claims it is the fastest process ever measured, although some might quibble with that distinction. I’m afraid I only grasped her group’s methodology in small chunks — that’s the trouble with talks sometimes — but you can read more in a paper published in Nature Physics last year.
One development that isn’t addressed in the paper, but which Keller touched on in her talk, is just how controversial their result has been among theorists. The idea that tunneling takes a tiny but finite time makes some intuitive sense, but this is quantum mechanics — intuitive sense doesn’t always come into it. Indeed, some theorists have predicted that the electron’s escape literally takes no time at all, while others suggest that tunneling isn’t even the right way to look at the process.
The arguments on this have become so heated, Keller says — half-jokingly I think — that a few of the people involved aren’t on speaking terms anymore. One thing is clear: the debate on electron tunneling is sure to carry on much longer than the process itself.
Physicists in the US have unveiled a new chip-based device capable of manoeuvring tiny objects using sound. These “acoustic tweezers” could provide a simpler and more energy-efficient alternative to the more established technology of optical tweezers, say the researchers. In addition, the small size and delicate functioning of the device could eventually lead to new “lab-on-a-chip” applications in medicine and industry.
The acoustic tweezers exploit a phenomenon known as surface acoustic waves (SAW) – sound waves that penetrate just one wavelength into a material when propagating along its surface. The researchers have combined two SAWs in their device to generate a standing wave across a chip. When a microscopic object is placed in the standing wave, it moves along a pressure gradient until it reaches a node – that is, a point where the two waves cancel each other out – and the object comes to a complete standstill.
Trapped in a standing wave
The researchers at Pennsylvania State University, led by Jinjie Shi, fabricated their device on a piezoelectric chip. The acoustic waves are generated from transducers along the edges of the chip, which convert the tiny electric currents into pressure fluctuations. Finally, a series of microchannels filled with fluid are etched into the chip using photolithography, to lubricate the movement of particles.
To demonstrate the acoustic tweezers, the researchers arranged a series of fluorescent polystyrene beads about 1.9 µm in diameter into a grid pattern. They then carried out the same demonstration using the red blood cells of a cow and the bacteria E.Coli.
Even though the wavelength of the acoustic wave is significantly longer than that of light, the fact that nodes are single points in space makes the precision of acoustic tweezers higher, in theory, than optical tweezers. The researchers say that the new device has several other advantages over optical tweezers, which are a more established technology that uses the momentum of light to move microscopic objects. One of the main benefits for medical usage is that the acoustic tweezers can be used to manipulate living cells without inflicting any damage or killing them.
Lab on a chip
The hope is that the optical tweezers can be integrated into a single chip that can perform single or multiple functions in what is often termed a “lab-on-a-chip”. “A platform based on the acoustic tweezers could make a system with specific applications such as blood analysis, cell studies and tissue engineering,” Shi told physicsworld.com.
Another potential advantage is the cost and manufacture process. “The energy intensity requirement in acoustic tweezers is 500,000× lower than in optical tweezers,” says Shi. “The easy fabrication and high yield also make the acoustic tweezers extremely low cost ($20 per set) in comparison to the optical tweezers (more than $100,000 per set).”
One limitation of the present design, however, is that the patterns of microscopic objects are fixed once formed. Shi says that his team is now working to overcome this problem by developing a set of tuneable tweezers using slanted transducers to generate acoustic waves.
This research will be published in an upcoming edition of Lab on a Chip.
Researchers at the University of Bristol in the UK have made a prototype optical quantum computer chip and used it to perform a mathematical calculation for the first time. The device consists of tiny silica waveguides on a silicon chip and carries out a version of the quantum calculation known as Shor’s algorithm. The result is an important step towards making practical, real-world quantum computers, says the team.
The team used the chip to calculate the prime factors of 15 to output the answer 3 and 5. Finding prime factors is a crucial part of modern encryption schemes, such as those employed for secure internet communications.
While classical computers store and process information as “bits” that can have one of two states – “0” or “1” – a quantum computer exploits the ability of quantum particles to be in “superposition” of two or more states at the same time. Such a device could, in principle, outperform a classical computer on some tasks. In practice, however, physicists have struggled to create even the simplest quantum computers because the fragile nature of quantum bits – or qubits – makes them very difficult to transmit, store and process.
Ideal qubits
Photons are a popular choice for qubits because they can travel great distances through optical fibres or even air without losing their quantum nature. This is because individual photons do not normally interact with each other. However, this also means that it is difficult to make devices for processing quantum information, such as logic gates, which rely on two or more photons interacting.
In 2003 Jeremy O’Brien, with colleagues at the University of Queensland, Australia, overcame this problem by building the first controlled NOT (CNOT) quantum logic gate for single photons. A CNOT gate has two inputs – “target” and “control” – and is thought to be a fundamental building block of any quantum computer. However, this first gate was made using conventional optical components, such as mirrors and beam splitters, and took up an entire laboratory bench.
A newer version, developed last year by O’Brien at Bristol, contained hundreds of versions of the same CNOT gate in a piece of silicon just a millimetre in size. This device used coupled waveguides – micron-wide channels of transparent silica that can be grown on silicon substrates using well established industrial processes – instead of mirrors and beam splitters.
First maths calculation
The team has now taken this work a step further by making the device perform the first mathematical calculation. Four photons travel through the waveguides and structures called H gates then prepare each qubit in a superposition of 0 and 1, so that the entire state is a superposition of all four-bit inputs. The calculation is then performed by two other, CZ, gates that create a highly entangled output state. Measuring the output states of the first two qubits produces the results of the calculation.
The computation is done using Shor’s algorithm, named for mathematician Peter Shor who invented it in 1994. In his work Shor predicted that quantum computers could factor numbers exponentially faster than their classical counterparts.
“Although this task could be done much faster by any school kid, ours is a really important proof-of-principle demonstration,” said team member Alberto Politi of the University of Bristol.
“The really exciting thing about the result is that it will enable the development of large scale quantum circuits, which opens up all kinds of possibilities,” added O’Brien.
“Just add qubits”
“This certainly is an interesting and important result,” commented Boris Blinov of the University of Washington, who was not involved in the study. “Integration will be crucial for any successful quantum information technology and here we witness a major step forward in integrating components of a linear-optical quantum processor. It’s a really nice technology – the quantum logic gates are literally built, and all you have to do is just add qubits. And the gate fabrication process seems readily scalable to much larger arrays for more complicated computational tasks (than finding the prime factors of number 15!)”
The “just adding qubits” part could be more complicated than we think though, he stresses, because reliable sources of single photons will be needed – something that is still difficult to achieve. A potential solution could be to combine the linear-optical quantum processor with qubits other than photons. “These include trapped ions or quantum dots – the future of this technology,” Blinov said.
Ever since magnetic monopoles were first predicted by Paul Dirac in 1931, physicists have looked in vain for these elusive entities in everything from particle accelerators to Moon rocks. Now, two independent research groups claim to have caught sight of monopoles – essentially magnets with only one pole – in magnetic materials called spin ices.
The spin-ice monopoles have very different origins from those predicted by Dirac’s work on quantum electrodynamics and therefore their discovery is unlikely to help physicists develop grand unified theories of particle physics or string theories. But because the monopoles occur in magnetic materials, understanding their properties could help with the development of magnetic memories and other spintronic devices.
International collaborations
One team included Tom Fennell and colleagues at the Institute Laue-Langevin (ILL) in France along with physicists in the UK. The other included Jonathan Morris and colleagues at the Helmholtz Centre in Berlin (HZB) along with scientists in the UK, Argentina and Germany.
The Morris group studied the crystalline material Dy2Ti2O7, which has a tetrahedral unit cell with two Dy spins pointing into the centre of the tetrahedron and two pointing out. It is called a spin ice because the arrangement of spins is similar to that of hydrogen atoms in frozen water.
The spins in a spin ice do not line up like those in a ferromagnet. Instead physicists believe that they join up to create magnetic flux lines within the material that resemble a knotted mess of strings. These are known as Dirac strings because they resemble the tubes of flux that should connect magnetic monopoles according to Dirac’s calculations.
If the spin configuration of an individual tetrahedron is disrupted – say, by flipping a spin from “out” to “in” – a string is broken and the magnetic flux spills out in a manner resembling a monopole.
Morris and colleagues applied a magnetic field to their spin-ice sample and found that the stings began to break into finite sections that line up along specific directions in the material. This was revealed by firing a beam of neutrons at the sample and studying the interference pattern that results when the neutrons (which have magnetic moments) scatter from the strings.
Each finite string has a “north” and “south” end and physicists believe that under certain conditions the length of the string can change easily. As a result, the ends of the string will appear to behave as two individual “quasiparticles” – north and south monopoles.
While the Morris group was able to ‘see’ the Dirac strings with neutrons, they inferred the existence of monopoles by measuring the heat capacity of the spin ice. Physicists had calculated that at temperatures of around 1 K the heat capacity of a spin ice should resemble that of a gas of magnetic monopoles – which is exactly what Morris and team saw.
Pinch points to Coulomb phase
Theoretical representation of ‘pinch points’ that arise in neutron scattering experiments on spin ices. Their presence suggests the existence of a magnetic Coulomb phase. (Courtesy: Tom Fennell, ILL)
Meanwhile at the ILL, Fennell and colleagues used a beam of spin-polarized neutrons to study a similar spin ice – Ho2Ti2O7. They were particularly interested in studying the ground states of the spin ice to establish if they can indeed support monopole excitations. At low temperatures and zero magnetic field, physicists had predicted that, in order to have monopoles, this knotty mess of a state must be a “magnetic coulomb phase” – which the team confirmed through the observation of “pinch points” in their neutron scattering data.
In the absence of finite strings and monopoles, the pinch points are very sharp. However at temperatures of around 1 K the thermal excitation of monopoles creates finite strings, which broaden the pinch points – which is what the researchers saw in their neutron diffraction data.
Fennell told physicsworld.com that the team is now trying to measure the width of the pinch point, which should give the length of the Dirac strings. Meanwhile, the Morris group is busy measuring the heat capacity of its spin ice as a function of applied magnetic field – which should provide further insight into the magnetic monopoles.
Oleg Tchernyshyov at Johns Hopkins University in the US said that the findings of both teams are in agreement with a theory (see “‘Spin ice’ could contain magnetic monopoles”) that was unveiled last year by several of Morris’s colleagues. However, he cautions that the theory and experiments are specific to spin ices, and are not likely to shed light on magnetic monopoles as predicted by Dirac.
One important general result of the research, according to Morris, is that the spin ice monopoles are one of the first examples of “fractionalization” – whereby a spin is split into two separate entities – in a 3D system. A familiar 2D example of fractionalization is the fractional quantum Hall effect, the discovery of which resulted in Robert Laughlin, Horst Störmer and Daniel Tsu winning the 1998 Nobel Prize for Physics. Because this and other properties of spin ices should be shared by similar magnetic materials, it could lead to the development of new materials for making spintronics devices, such as magnetic memories.
His pioneering work in the 1940s is arguably the reason you are reading from this screen.
His code-breaking skills also helped to defeat the fascist onslaught during the Second World War.
His eponymous test to gauge the “intelligence” of a machine is taken as an essential concept in the field of artificial intelligence.
But rather than enjoy the fruits of his work in the latter half of the 20th century, Alan Turing tragically died in 1954 aged just 41, after biting into an apple laced with cyanide. Though there is still some controversy surrounding his death, the general consensus is that Turing killed himself after being given the choice of prison or chemical castration on account of his homosexuality.
Now, over fifty years later, a computer scientist is calling for the British government to finally apologize for the manner in which Turing was treated.
The British Government should apologize to Alan Turing for his treatment and recognize that his work created much of the world we live in and saved us from Nazi Germany. And an apology would recognize the tragic consequences of prejudice that ended this man’s life and career
At the time of writing, more than 26 000 people have added their name to the petition.
An international team of astrophysicists has mapped the borderlands between two of our neighbouring galaxies to reveal an ongoing galactic jostle that will eventually result in the formation of one super-galaxy incorporating the Milky Way. The findings provide the first qualitative evidence outside of the Milky Way that galaxies evolve through the merging of smaller galaxies.
Alan McConnachie of the NRC Herzberg Institute of Astrophysics, Canada, and his colleagues in the US, Europe and Australia set out to shed new light on the dynamics of galaxy evolution. They focused on two of our closest galactic neighbours to establish the extent and nature of any interaction that may be taking place. To do this, they combined computer simulations with new images captured by the Canada-France-Hawaii Telescope (CFHT) located near the summit of Mauna Kea in Hawaii.
First, the researchers surveyed Andromeda, which is the closest large galaxy to the Milky Way and contains a similar number of stars – around 100 billion. While the central disc of Andromeda is one of the most photographed objects in the sky, the outer sections are still relatively unobserved. McConnachie and his team have now vastly extended the survey and show that Andromeda has stars stretching over an area more than 100 times larger than the central disc. “The fact that we are looking so far out from the centre of the galaxy, and yet still detecting stars in this galaxy at these positions, really demonstrates just how large this galaxy is,” says McConnachie.
Ripping off a limb
Next, the researchers turned their attention to one of Andromeda’s smaller satellites, Triangulum – a densely-packed galaxy of about one-tenth the size of its spiral neighbour. What they observed was an extended, stream-like structure protruding from Triangulum in the direction of Andromeda. They conclude that this structure is very similar to what they would expect to see around a smaller galaxy that is interacting with a massive galaxy that is “ripping” stars from it.
Having made these observations, the researchers then looked to see if the laws of physics would permit such a violent interaction of this kind, given that we know these galaxies are moving in a certain way in relation to each other. Using computer simulations, they estimate that this stellar assault must have occurred roughly 2 billion years ago when Triangulum passed within 100,000 light years of Andromeda.
According to McConnachie, the encounter was aggressive but it was still a long way from being a head-on collision. The astrophysicist warns, however, that Triangulum may not come off so lightly when the two galaxies interact again, which is likely to occur within the next 2 billion years. “It’s unlikely Triangulum will be able to escape this time, and it’s very likely that the two galaxies will completely merge together soon afterwards.”
The fate of the Milky Way
By the time Triangulum is approaching Andromeda again, the Milky Way and Andromeda will have moved much closer together. McConnachie predicts that all three galaxies will probably collide together at the same time resulting in a merger and the formation of a new, larger galaxy. This process is a common occurrence in the “hierarchical” model of galaxy evolution.
Nickolay Gnedin, a member of the Theoretical Astrophysics Group at Fermilab in the US, believes that this new research is important because it extends our picture of galaxy evolution beyond our own galaxy. “The Milky Way is a wonderful galaxy and we learned a great deal about galaxies in general from it alone, but one can never be sure that the Milky Way is not special or unusual in some particular way, so a confirmation from a different galaxy is very important.”
Gnedin also believes that Andromeda and Triangulum will merge within a few billion years but he has a slightly different take on the fate of the Milky Way. “The merger between Triangulum and Androme will not gobble up the Milky Way, but the Milky Way and Andromeda will collide and merge together in about 3 billion years.”
This research is published in the latest edition of Nature.
Over the past decade, physicists have been very successful at using optical lattices of ultracold atoms as “quantum simulators” to study interactions similar to those involved in superconductivity and other properties of solids. However, scientists had been unable to remove atoms from specific optical lattice sites – something that would allow these simulators to mimic a wider range of solid materials. Now, Herwig Ott and colleagues at Johannes Gutenberg University, Germany, have shown that it is possible to vacate lattice sites by firing an electron beam at the atoms.
Ott’s team began with tens of thousands of rubidium atoms that were cooled to temperatures fractionally above absolute zero. “Rubidium is the easiest element to laser cool – that is why we are using it,” explained Ott.
A 2D optical lattice with a periodicity of 600 nm was created by the interference pattern made by two perpendicular laser beams. Each lattice site had an average of 80 atoms, which were trapped by the optical dipole force created by the lasers.
The extremely low temperature of the atoms (about 100 nK) caused the collections of atoms at every site to behave as a Bose–Einstein condensate, which means that all the atoms are locked together in the lowest quantum state of the system.
Last year the team developed the first technique for taking images of the lattice by scanning an electron beam across the lattice and peering into individual lattice sites. Now, the researchers have adapted the technique to remove atoms from specific sites.
The electron beam causes some rubidium atoms to be ionized – and these are extracted from the lattice by an applied electric field. Other atoms just scatter electrons, but these atoms receive a kick that is large enough to overcome the dipole force that keeps them in the optical lattice. “If we shine [the electron beam] long enough into a lattice site, all the atoms are eventually removed,” Ott told physicsworld.com.
The team then confirmed the vacancies in the lattice using their electron-beam imaging technique. Indeed, the physicists were able to create and image a number of different patterns in the lattice including Schrödinger’s equation EΨ = HΨ.
Steve Rolston from the University of Maryland believes that one of the strengths of Ott’s work is that it sidesteps the use of optical techniques for imaging the lattice. “Most everyone to date has been using optical detection, which suffers from the diffraction limit,” he said. This prevents the resolving of details smaller than the optical spacing.
Rolston says that it is difficult to predict how much impact this work will have of other researchers in this field. “The patterning application will probably come first – because even if you cannot detect single atoms, you can probably be confident that you can destroy them with a high probability.
“This will allow the creation, by hand, of novel spatial states, which can allow much more flexibility in exploring the states of many-body systems.”
