Cloud Chamber

A cloud chamber (CC) is used to detect tiny radiation particles. It was invented by Wilson and won him a Nobel Prize. The operating principle is simple: soak a chamber with alcohol and then seal it, and cool it down. The supercooled air shall enter a metastable state but the alcohol evaporation get ready to condense, which can be ignited by a small perturbation (nucleation centers). When a particle passes through this chamber, liquid drops shall track it and make it detectable.

This is a Video demonstrating how to make a simple cloud chamber:
http://education.jlab.org/frost/cloud_chamber.html

Note: a metastable state is a state that is stable but not robust against any perturbations.

Inventing new physical systems

Particle physicists can hardly invent new physical systems but only to discover the already existing matter and energy world. Condensed matter physicists tend to create their own systems to meet fundamental intelligent challenges and practical ends. The as-created new physical systems are surely immense and the underlying physics are also diverse, but the mathematical models seem not so diverse: it is frequently the case that the model constructed for one system may be transplanted to describe another system, with proper interpretation of the symbols. In other words, there exists some kind of universality. This scenario offers opportunities for both theorists and experimentalists: (1) the theorists can make predictions about system A via the knowledge of system B if A and B are found sharing the same mathematical structure; while (2) the experimentalists can simulate system A by measuring system B. Such possibility drives the emergence of a host of artificial systems. The following is a list:
(1) p-n junction and transistors;
(2) 2DEG;
(3) Optical lattice and Ultra-cold atoms;
(4) Photonic crystals;
(5) Metamaterials;
(6) Circuit QED;
(7) Cavity QED;
(8) Trapped ions;
(9) Graphene, and CNTs;
(10) Topological insulators;
(11) ...

Edison and his carbon filament bulbs

Harnessing electricity for light had been an ambition over a century ago. Edison had caught that rush for incandescent bulbs. A lasting incandescent bulb must have a filament that won't be burnt quickly and thus bear a long life. To have this, the filament has to be protected from chemical reactions that damage its property. At that time, vacuum is the choice. Edison first figured out the way to pump air and then looked for the desired filament and eventually found one, the bamboo ! Interestingly, it is also the same bamboo under the same arc that led Ijishima to his carbon nanotubes !
[http://www.wired.com/thisdayintech/2009/10/1021edison-light-bulb/]

Edison’s lab put a lot of effort into making a bulb with a platinum filament, but that work went nowhere, because platinum has a relatively low resistance. But gas bubbles in the platinum had led Edison to develop an efficient vacuum pump to remove the air from the inside of his bulbs. And that created a new opportunity: carbon.

Carbon conducts electricity, has a high resistance and can be shaped into thin filaments. And it’s cheap. But it burns easily — unless there’s no oxygen around. The vacuum bulbs Edison had created for platinum were ideal for carbon.

Edison pushed hard on his research assistants, whom he more or less affectionately called “muckers.” After testing hundreds of materials, they baked a piece of coiled cotton thread until it was all carbon. Inside a near-vacuum bulb, it stayed alight for more than half a day. The “three or four month” project had taken 14 months.

Soon, the lab got a carbon-filament bulb to last 40 hours. It had cost $40,000 (about $850,000 in today’s money) and taken 1,200 experiments, but was ready at last for a public debut.

comic physics

Don't let yourself miss this funny stuff !

Thermofluidic effects in nanochannels

When a fluid is subject to a temperature gradient, a velocity field can be generated, a phenomenon known as convection. It should be noticed that, such phenomena parallel what happens to electrons in a metal: temperature gradient drives electrical current under the name of thermoelectric effect. Now as things can be made smaller and smaller, it becomes an interesting subject to investigate the so-called micro- or nano-fluidic flow: liquid flow through a micro-size or nano-size channel. In this study by researchers from Hong Kong [PRL 105, 174501 (2010)], they used molecular dynamics simulations to examine a nano fluid housed in a nano-channel with particularly designed walls: the wall consists of two parts, the left and the right one, with respective surface energies, and a temperature gradient is held symmetric with respect to the border between the left and right wall. Their study showed that, an asymmetric flow can be generated with this temperature gradient provided the variance of surface energies is big enough. This is funny and many possibilities can be imagined to broaden their studies.

Quantum grativity in its present status

This is a nice article that was originally used as lecture notes in the Stockholm workshop. It gives a concise account of the present understanding of quantum gravity and and the arguments go at the heart. It also maps the planing for experimental search. In addition, rich references can be found.
[http://arxiv.org/PS_cache/arxiv/pdf/1010/1010.3420v1.pdf]

Curved space generating mass ?

Since Newtonian times, physicists have to talk of mass, a quantity having its origin a deep myth. In Newtonian mechanics, mass is impedes the change of velocity. In relativity, mass (in the conventional sense) is no more than the static energy. In non-relativistic quantum mechanics, mass plays to make the entity more of a particle. In relativistic quantum mechanics, mass is the energy required to generate a pair of electron and positron. In condensed matter physics, mass is the minimum energy to excite a system. Besides, mass also measures some correlation length.

Although we know many things about mass, we don't have a clear clue where mass comes from. In the standard model, all masses are produced by Higss mechanism: every mass-less particle moves in some kind of ether that is the Higgs clouds and acquires mass. Another idea is, mass can be generated by curved space, or more accurately, compactified dimension. Compactifying a dimension yields finite motion, one that is confined. According to quantum mechanics, finite motion implies discrete levels and finite gaps, so comes the mass. Yet, a clear regime is missing.

Graphene provides a playground for studying this regime. These authors roll the graphene and obtain a massive 1D system from a 2D massless Dirac system [http://arxiv.org/ftp/arxiv/papers/1010/1010.3437.pdf]. This is no surprising and actually was known before. But this is an example showing how mass might be generated this way. However, back to elementary particle physics, where is the hidden dimension in addition to the 4D space-time we are all used to ? Another question is, how the as-obtained masses interact in a gravitational way ? Anyway, mass should be gravitationally active !!!!

Twitter predicts Stock Market ?

This study is really astounding. The researchers from Indiana University found likely correlations between the calmness index that can be tallied by twitter data and the price walk of stock market [http://www.technologyreview.com/blog/arxiv/25900/].

Today, Johan Bollen at Indiana University and a couple of pals say they've found just such a predictor buried in the seemingly mindless stream of words that emanates from the Twitterverse.

For some time now, researchers have attempted to extract useful information from this firehose. One idea is that the stream of thought is representative of the mental state of humankind at any instant. Various groups have devised algorithms to analyse this datastream hoping to use it to take the temperature of various human states.

One algorithm, called the Google-Profile of Mood States (GPOMS), records the level of six states: happiness, kindness, alertness, sureness, vitality and calmness.

The question that Bollen and co ask is whether any of these states correlates with stock market prices. After all, they say, it is not entirely beyond credence that the rise and fall of stock market prices is influenced by the public mood.

So these guys took 9.7 million tweets posted by 2.7 million tweeters between March and December 2008 and looked for correlations between the GPOMS indices and whether Dow Jones Industrial Average rose of fell each day.

Their extraordinary conclusion is that there really is a correlation between the Dow Jones Industrial Average and one of the GPOMS indices--calmness.

In fact, the calmness index appears to be a good predictor of whether the Dow Jones Industrial Average goes up or down between 2 and 6 days later. "We find an accuracy of 87.6% in predicting the daily up and down changes in the closing values of the Dow Jones Industrial Average," say Bollen and co

That's an incredible result--that a Twitter mood can predict the stock market--but the figures appear to point that way.

Is it really possible that the calmness index is correlated with the stock market? Maybe. Back in April we looked at some work showing how tweets about films can be used to predict box office takings.

But there are at least two good reasons to suspect that this result may not be all it seems. The first is the lack of plausible mechanism: how could the Twitter mood measured by the calmness index actually affect the Dow Jones Industrial Average up to six days later? Nobody knows.

The second is that the Twitter feeds Bollen and co used were not just from the US but from around the globe. Although it's probably a fair assumption that a good proportion of these tweeters were based in the US in 2008, there's no way of knowing what proportion. By this reckoning, tweeters in Timbuktu somehow help predict the Dow Jones Industrial Average.

If so, what might happen to the way people play with stocks ?

Wet dog shaking

This piece of study is something that should never be missed. It is perhaps one of the best examples exemplifying what science is all about: Just being curious and trying to find out how things actually happen. This work looks at how fast a wet dog wriggles its body to shake off the water sticking to its fur. These authors from Geogia Insttitute of Technology set up a model and compare the results out of this model to reality. They photographyed a range of animals and figure out the wriggling frequencies. Their model predicted the frequency should be proportional to the square root of the belly radius of the animals, close to the observations that yield an exponent of 0.75 rather than 0.5. [http://www.wired.co.uk/news/archive/2010-10/20/physicists-find-perfect-speed-for-wet-dogs-to-shake-at] In this link, there is a video that sumarizes their interesting and provoking work.

Physics assailing cancers

This must be a very useful resource compilation on the stories of attacking problems of cells by physics. [http://www.nature.com/nphys/journal/v6/n10/pdf/nphys-insight-physics-cell.pdf]

Principles and methods from the physical sciences have long been applied to questions in biology; however, the application of such principles to the study of cancer biology has only begun to flourish. In the latter part of the 20th century, and especially the last decade, advanced technologies have fueled an unprecedented period of discovery and progress in the molecular
sciences that promises to revolutionize cancer medicine. In 1999, the National Institutes of Health Director, Harold Varmus highlighted this point in his speech at the Centennial Meeting of the American Physical Society by stating, “Biology is rapidly becoming a science that demands more intense mathematical and physical analysis than biologists have been accustomed to, and such analysis will be required to understand the workings of cells.” This issue of Nature Physics Insight – Physics and the Cell reviews a number of areas in which physical scientists are tackling biological problems relating to cells and their interaction with their surroundings.

Failed theories of SC

In one of my previous entries, I mentioned the failed theories that were briefly reviewed in a preprint. Here in Nature Physics [Nature Physics, 6: 715, 2010], another one based on this review came out. I especially like this story about Laudau:

Yet it turns out that Landau first proposed these ideas in the context of superconductivity, thinking not of magnetization but of electrical current. He expanded the free energy F around the state of zero current, j = 0, and argued that as the direction of the current shouldn't affect F, the odd terms should vanish. This gives an equation of the form F(j) = F(0) + aj² + bj⁴. Assuming b > 0 and that a passes through zero at a critical temperature T_c, he showed that there could be an abrupt transition from zero to non-zero current below T_c.

This early theory conflicted with observations — it erroneously predicted j ~ (T_c − T)^1/2 just below the critical temperature — and Landau went back to the drawing board. Yet here already were the seeds of the later Ginzburg–Landau theory of phase transitions. And Landau's introduction of the notion of an 'order parameter' as a convenient handle on order and how it changes has influenced physics ever since, even if it did appear in a failed theory.

This idea is crazy: when one expands free energy in current, one has in his mind that he is dealing with an equilibrium state. However, current usually exists in a non-equilibrium state. This gives a glimpse of the aberration of superconductivity !

A circuit that beats Jaynes–Cummings model

In circuit quantum electrodynamics1–10 (QED), where superconducting
artificial atoms are coupled to on-chip cavities, the exploration of fundamental quantum physics in the strongcoupling regime has greatly evolved. In this regime, an
atom and a cavity can exchange a photon frequently before coherence is lost. Nevertheless, all experiments so far are well described by the renowned Jaynes–Cummings model11. Here, we report on the first experimental realization of a circuit QED system operating in the ultrastrong-coupling limit12,13, where the atom–cavity coupling rate g reaches a considerable fraction of the cavity transition frequency !r. Furthermore, we present direct evidence for the breakdown of the Jaynes–Cummings model.We reach remarkable normalized coupling rates g=!r of up to 12% by enhancing the inductive coupling14 of a flux qubit to a transmission line resonator. Our circuit extends the toolbox of quantum optics on a chip towards exciting explorations of ultrastrong light–matter interaction. [DOI: 10.1038/NPHYS1730]

Does noise entail decoherence ?

Every system is in contact with its surroundings and is thus an open system. It is not possible to have exact information about its surroundings, implying a statistical treatment of the interactions between the system and its surrounding. In equilibrium thermodynamics, a statistical weight can be assigned to effect the surrounding. However, in non-equilibrium cases, where dynamics are crucial, noises of certain type are supposed to capture the physics. Usually, white noises, which are the noises from, let's say, a heat bath, cause de-coherence of quantum states. How about 1/f noises ? This kind of noise is pointing and may not be so detrimental. In this piece of work, the authors theoretically examined the fate of a quantum critical state under such 1/f noise. They found that, the criticality can be preserved. To investigate the nature of a system, one may either look at its ground state (by considering static response to certain stimuli) or its excited states (by inspecting its dynamic response to certain stimuli) or both. Basically, these methods should be the same: from G-state one could have some idea (just some idea based on clever guess) what the E-states might be and vice-versa. In many cases, the G-state is preferred, because once the G-state is known, it shows at least how to construct low energy excitations (again, vice versa). In this work, they of course have to study the excitations, since it is a non-equilibrium system. [NATURE PHYSICS, VOL 6, OCTOBER 2010 ,www.nature.com/naturephysics]

Quantum critical points are characterized by scale-invariant correlations and therefore by long-range entanglement. As such, they present fascinating examples of quantum states of matter and their study is an important theme in modern physics.
However, little is known about the fate of quantum criticality under non-equilibrium conditions. Here we investigate the effect of external noise sources on quantum critical points. It is natural to expect that noise will have a similar effect to
finite temperature, that is, destroying the subtle correlations underlying the quantum critical behaviour. Surprisingly, we find that the ubiquitous 1=f noise does preserve the critical correlations. The emergent states show an intriguing interplay of
intrinsic quantum critical and external-noise-driven fluctuations.We illustrate this general phenomenon with specific examples describing solid-state and ultracold-atoms systems. Moreover, our approach shows that genuine quantum phase transitions can exist even under non-equilibrium conditions.

Molecular superfluidity ?

Bosons could become superfluid at low temperatures: it flows without feeling the friction. This is so due to the opening of an energy gap as bosons condense into a so-called macro-molecule in the presence of interactions. It is expected that such condensation happens at a number of bosons. Now it was demonstrated that, this number can be down to 9 pH2 molecules.

Clusters of para-hydrogen (pH2) have been predicted to exhibit superfluid behavior, but direct observation of this phenomenon has been elusive. Combining experiments and theoretical simulations, we have determined the size evolution of the superfluid response of pH2 clusters doped with carbon dioxide (CO2). Reduction of the effective inertia is observed when the dopant is surrounded by the pH2 solvent. This marks the onset of molecular superfluidity in pH2. The fractional occupation of solvation
rings around CO2 correlates with enhanced superfluid response for certain cluster sizes. [PRL 105, 133401 (2010)]

Better surface Dirac states

Topological insulators are insulators that house gapless surface states. These states provide playground for a host of Dirac physics. Although a couple of such materials have been found, this newly examined one has some better features:

In summary, our ARPES experiment of TlBiSe2 has revealed three important aspects: First, the surface state Dirac cone is confirmed to be present at the Gamma point. Second, the Dirac cone is practically ideal, especially near the DP, and its velocity is larger than for Bi2Se3. Finally, according to both experiment and theory, there are no bulk continuum states that energetically overlap with the DP. This means that the scattering channel from the topological surface state to the bulk continuum is suppressed. Our experimental results favor the realization of the topological spin-polarized transport with high mobility and long spin lifetime in TlBiSe2. [PRL 105, 146801 (2010)]

Switching polarization in FE in a continuous way

Due to symmetry, domains usually occur in any ferroics. Each domain represents one episode of possible low energy configurations that are allowed by symmetry. Domains are separated by domain walls. Every wall has a definite thickness, across which the order parameter changes continuously but rather steeply. By applying an external field, the polarization of a domain can be switched, either continuously or abruptly. In this experiment [PRL 105, 167601 (2010)] on a PbTiO3 thin film, the switching takes place in a continuous way: the original polarization gradually diminishes to zero as the field increases and grows up in the other direction from zero. There is no threshold value required. It might be a very interesting question to study the general conditions for continuous and abrupt switching.

Magnetic oscillations observed in Cuprates and their implications

There have been the very prolonged debate on the nature of the fermi surface measured of cuprate superconductors. Magnetic oscillations are the conventional probe in mapping out the surface. Here is an overview [Physics 3, 86 (2010)] of what has been learned in this field, with a useful list of resource references.

CO2 as the climate control knob

Ample physical evidence shows that carbon dioxide (CO₂) is the single most important climate-relevant greenhouse gas in Earth’s atmosphere. This is because CO₂, like ozone, N₂O, CH₄, and chlorofluorocarbons, does not condense and precipitate from the atmosphere at current climate temperatures, whereas water vapor can and does. Noncondensing greenhouse gases, which account for 25% of the total terrestrial greenhouse effect, thus serve to provide the stable temperature structure that sustains the current levels of atmospheric water vapor and clouds via feedback processes that account for the remaining 75% of the greenhouse effect. Without the radiative forcing supplied by CO₂ and the other noncondensing greenhouse gases, the terrestrial greenhouse would collapse, plunging the global climate into an icebound Earth state.

http://www.sciencemag.org/cgi/content/full/330/6002/356

Topological Insulators used to determine fundamental constants

Topological phenomena (TP) play crucial role in determining the precise values of fundamental constants such as elementary charge, Planck constant and speed of light. This is so because of the robustness of topological phenomena against local variation in samples and also weak disorder and interactions between particles. Some famous TP have already been in use to this end: the quanta of magnetic flux has been measured with circular superconducting devices; the electrical conductance has been measured with the help of quantum Hall effect. Recently, a new TP was discovered in materials now known as topological insulators (TI). These materials are characterized by their bulky band gap and gapless surface states that are topologically robust. Examples include Te-Bi type compounds. It is expected that, such TP may also be employed to improve the precision of measurement. This came to realization in a latest publication [PRL 105, 166803 (2010)]:

Fundamental topological phenomena in condensed matter physics are associated with a quantized electromagnetic response in units of fundamental constants. Recently, it has been predicted theoretically that the time-reversal invariant topological insulator in three dimensions exhibits a topological magnetoelectric effect quantized in units of the fine structure constant ¼ e2=@c. In this Letter, we propose an optical experiment to directly measure this topological quantization phenomenon, independent of material details. Our proposal also provides a way to measure the half-quantized Hall conductances on the two surfaces of the topological insulator independently of each other.

Friction not so simple

Friction is certainly a standard part of middle school physics courses. It is observed that, to move an object in contact with another one, a force must be applied larger than the static friction, which is supposed to be uniform across the interface. However, this picture is inadequate. Actually, it was perceived that non-uniformity occurs at least locally. Understanding the nature of friction and how to model it better is not only theoretically interesting but practically imperative, because friction is relevant to a plenty of phenomena, such as rampant earthquakes and snow ruptures. Friction is the force that holds those events from bursting out. On the hand, it is also desirable to gain insight into how slip occurs locally when friction fails. This is key to modeling. This latest publication investigated this problem.

The way in which a frictional interface fails is critical to our fundamental understanding of failure processes in fields ranging from engineering to the study of earthquakes. Frictional motion is initiated by rupture fronts that propagate within the thin interface that separates two sheared bodies. By measuring the shear and normal stresses along the interface, together with the subsequent rapid real-contact-area dynamics, we find that the ratio of shear stress to normal stress can locally far exceed the static-friction coefficient without precipitating slip.
Moreover, different modes of rupture selected by the system correspond to distinct regimes of the local stress ratio. These results indicate the key role of nonuniformity to frictional stability and dynamics with implications for the prediction, selection, and arrest of different modes of earthquakes.

Molecules filtering spins

Using STM with a magnetic tip can be used to probe the magnetic feature of a surface. The tunneling current shall be sensitive to the alignment (collimation) between the spin orientation of the surface and that of the tip. If the tunneling, as is usually the case, is non-magnetic, then parallel alignment yield a bigger current. A very valuable aspect of STM is that this device probes the local properties of a material. This makes it especially useful in investigating defects or impurities of a surface. Now these authors [Phys. Rev. Lett. 105, 066601 (2010)] came to examine what will happen to the signal if the electrons tunnel from the Fe surface into the tip through a single organic molecule with Beneze rings. The result is this: this molecule allows more spin-up electrons to pass. So, it works as a selective valve, which may be tailored to specific applications that needs manipulate spin current. This phenomenon was predicted 3 years ago in Ref.[3], where the computation was implemented in the aid of DFT. However, it may prove more elucidating if a simple model description is prescribed.
For convenience, some references are attested on this subject:

1. Atodiresei, N. et al. Phys. Rev. Lett. 105, 066601 (2010).
2. Brede, J. et al. Phys. Rev. Lett. 105, 047204 (2010).
3. Rocha, A. R. & Sanvito, S. J. Appl. Phys. 101, 09B102 (2007).
4. Barraud, C. et al. Nature Phys. 6, 615–620 (2010).
5. Sanvito, S. Nature Phys. 6, 562–564 (2010).
6. Cinchetti, M. et al. Nature Mater. 8, 115–119 (2009).
7. Drew, A. J. et al. Nature Mater. 8, 109–114 (2009).
8. Szulczewski, G., Sanvito, S. & Coey, J. M. D. Nature Mater. 8, 693–695 (2009)

Pioneering papers on Graphene

1. Novoselov, K. S. et al. Science 306, 666-669 (2004). | Article | PubMed | ISI | OpenURL | | ChemPort |
2. Zhang, Y. et al. Nature 438, 201-204 (2005). | Article | PubMed | ISI | OpenURL | | ChemPort |
3. Novoselov, K. S. et al. Nature 438, 197-200 (2005). | Article | PubMed | ISI | OpenURL | | ChemPort |
4. Kim, K. S. et al. Nature 457, 706-710 (2009). | Article | PubMed | OpenURL | | ChemPort |

Robert Edwards: The father of test tube babies

Now his work has been widely recognized and utilized, leading to four million lives that would not come at all without his work, although the church still criticizes him. It reminds how hard for new things to develop. It is the normal minds, which makes the biggest number, that impedes the few great ones. When new things come, these mediocre automatically try to crush them, rather than to rethink about their current situations and see if they can adapt. Such intolerance must have painful to Edwards.

Very few scientists can say that four million people are alive because of their work, but Robert Edwards is one of those few. His development of the technique at the heart of that claim — in vitro fertilization (IVF) — has won him this year's Nobel Prize in Physiology or Medicine.

To make IVF possible, Edwards had to solve numerous problems in basic biology — some of which opened the door for embryonic stem-cell research — while facing bitter opposition from churches, politicians and even some of his eminent colleagues at the University of Cambridge, UK. An outgoing yet thoughtful personality who eagerly engaged in public debate, Edwards was hurt by charges that his work was unethical.

But thanks also to his collaboration with another outsider, Patrick Steptoe, an obstetrician at the Oldham and District General Hospital, the world's first test-tube baby, Louise Brown, was born in 1978. Within five years, 150 test-tube babies had been born worldwide. Since then, IVF has become mainstream, and Edwards and Steptoe have been lauded for helping give life to millions. Had he not died in 1988, Steptoe would probably have shared the prize.

In 2001, Edwards won a Lasker award, which often presages the Nobel. Two years ago he celebrated the 30th anniversary of IVF at a symposium where the impact of this work on many levels of society — biology and medicine, but also law, ethics, the arts and social anthropology — was discussed. At 85, Edwards is now too frail to give interviews, but his wife told the Nobel Foundation of his happiness at receiving the prize. "No other scientist could have transformed so many aspects of our society," says Martin Johnson, one of Edwards's first graduate students and now professor of reproductive sciences at the University of Cambridge.

Edwards began his research career in the early 1950s working on the reproductive biology of mice. After harvesting eggs from female mice, he learned how to coax them, and eggs from other species, to mature and be fertilized in a test tube. He also worked out how to control the timing of the rodents' ovulation — which annoyingly tended to happen at night — by administering certain hormones.

Soon after he joined the National Institute for Medical Research in London in 1958, Edwards began applying his findings, and those of other groups working on reproductive biology, to humans. He acquired slices of human ovaries from surgeons, and from these he isolated immature eggs. He spent two disappointing years failing to coax them to mature in vitro, until he realized that the process required at least 24 hours of incubation, not the 12 hours that rodent eggs required. "It is these empirical observations that move science forward," says Ian Wilmut of the MRC Centre for Regenerative Medicine at the University of Edinburgh, UK, who also had to modify the conventional timing of cell incubation to create the first cloned mammal, Dolly the sheep. "These things seem very small in retrospect, but they are critical."

By 1968, Edwards had fine-tuned the maturation of human eggs, learning how to fertilize them with the potential father's sperm and to prod them into forming embryos that could be implanted. Having moved to the University of Cambridge he needed a collaborator to help him apply these techniques in human patients. Having read about Steptoe's pioneering work on laparoscopy — the placement of a fibre-optic endoscope into the abdomen to view internal organs — in his small hospital in northern England, Edwards picked up the phone. Steptoe was already using the method to withdraw fluid from the reproductive tract and agreed that he could also use it to extract eggs. Working as equal partners, the pair set out their own ethical guidelines, agreeing to stop if patients or children were endangered, but not in deference to what Edwards called "vague religious or political reasons".

The UK Medical Research Council refused to fund their work, believing it could lead to babies with severe abnormalities, and disapproving of the pair's high profile in the media (M. H. Johnson et al. Hum. Reprod. 25, 2157–2174; 2010).

Johnson recalls the "strange atmosphere" in the 1960s and 1970s, when the prospect of overpopulation seemed to be a bigger societal concern than infertility. "There was no awareness then of the personal pain of infertility," he says. "I remember eminent Cambridge scientists would tell us that our PhD supervisor was off his rocker." He also recalls Max Perutz and James Watson, both Nobel laureates at Cambridge, telling him it was irresponsible to interfere with the beginning of life. "Often people refused to speak to us in the tea room because they disapproved of what we were doing." Johnson stuck by Edwards though, finding him "inspirational and visionary".

The technique has not only benefitted infertile couples — it can also help parents to avoid passing on serious inherited diseases such as cystic fibrosis or Huntington's disease to their children, by selecting embryos that are free of dangerous mutations for implantation.

In addition, it has enabled the field of human embryonic stem-cell research. Reproductive biologist Outi Hovatta of the Karolinska Institute's IVF clinic in Stockholm, where new human embryonic stem-cell lines are derived from spare embryos, says that Edwards was the first, in 1984, to publicly discuss the benefits of such cells to medical research, and the ethical dilemmas that would inevitably accompany them. He was equally prescient on the need for oversight of his powerful technique, advocating in 1971 that a legal authority should be established to control IVF. The UK Human Fertilisation and Embryology Authority was founded 20 years later.

Scientists need a shorter path to research freedom

Usually a young needs to go through all the stages to arrive at its final intellectual autonomy, from undergrad, to PhD (sometimes even Mphil beforehand), and postdoc training. All these may take him around 15 years, which is very long and too long for the most gifted young who are highly creative and confident and motivated. Full pursuit freedom is quite essential to astounding ingenious findings. Einstein is the example. He acquired his independence by his uncompromisable desire for intellectual liberty and unbounded curiosity. Nothing could stop him from his zealous investigation. However, not all have his luck: he is with a incredibly strong heart that stems from his unfathomable passion and could overcome any balk ahead. Many young are talented but somewhat not that talented. They need a smoother academic environment to release their energy, or they would be throttled.

Nature 467, 635 (2010)

Over the past half-century, a great many things have changed in biomedical research. Along the way, postdoctoral training has become an established step in a research career. But this development has proved a double-edged sword for some — and possibly for the whole field.

Without question, postdoctoral training has enriched the experience of many by allowing protected time for full immersion in research. Postdocs provide essential skills and serve as first authors on many important papers, thus boosting research productivity. But these gains must be set against the significantly longer time it now takes for most young scientists to launch independent research careers. The average age of PhD scientists awarded their first research grant from the US National Institutes of Health (NIH) last year was 42. In 1981, the average was 36. As director of the NIH, I believe this is a problem that should be addressed. We must develop ways to liberate our brightest minds to pursue high-risk, high-reward ideas during their most creative years.

There are many complex reasons for the increased training periods, including an academic culture that emphasizes the need for longer, sometimes multiple, postdoc positions to build a stellar CV. There is a shortage of faculty vacancies, and institutions often insist that recruits win independent funding before appointing them to tenure-track posts. And there is too little emphasis on alternative scientific careers, such as industry, law, teaching and policy.

Many young researchers baulk at the prospect of such an extended period of limited intellectual autonomy. It is also a concern to veterans such as myself. I fear that science may be suffering because of a failure to encourage the independence of the next generation of great minds.

My own pathway to independence involved a three-year postdoctoral fellowship in human genetics in the lab of Sherman Weissman at Yale School of Medicine in New Haven, Connecticut. I was fortunate to be mentored by an adviser who encouraged autonomy and creativity. I used the opportunity to develop an innovative approach, called chromosome jumping, for crossing large strands of DNA to identify genes responsible for inherited disorders. It was a good launching pad; I received my first R01 grant from the NIH at age 34, the same year I began a faculty position at the University of Michigan in Ann Arbor.

In my lab at the NIH, I strive to cultivate the independence of young scientists as early as possible. One of my strategies is to assign new recruits a 'thinking period' devoted to formulating project ideas. Through an iterative process involving myself and the recruit, we refine the research direction until we have settled on a good fit. I think this strategy has worked well in encouraging forward thinking, but it may still be a halfway solution. For the most creative of young scientists, nothing can equal the chance to have a lab of one's own.

To provide such opportunities, several programmes aimed at promoting greater independence at earlier career stages have sprung up over the years, producing some spectacular investigators. And so, after much consultation with outside advisers, the NIH this week launched its own effort, the Early Independence Award Program (see http://go.nature.com/nFqYE5), which will initially support ten creative young scientists to pass almost immediately from completing a PhD to running their own laboratories. The awards will be paid by the NIH Director's Common Fund and administered through a peer-reviewed application process, supporting an investigator at a level of US$250,000 in direct costs per year for five years — the equivalent of a standard NIH R01 grant.

Unlike many similar programmes, the awards will give students flexibility to seek a position at any suitable institution. Applicants will need to work with the institution's academic leaders to negotiate an independent position that would be activated if they win an award. We hope that department heads will find this an attractive tool for recruiting talent to invigorate their institution's research environment. For its part, the institution must provide the young investigator with space and resources, and a level of mentoring equivalent to that provided to assistant professors.

I am aware that many speed bumps may lie on this expressway to independence. The programme requires highly motivated and mature applicants who are talented and confident enough to launch their own research programme and negotiate support from a department chair. And it requires institutions willing to support an award winner who will be unusually young in their career. The pilot programme, which we expect to be highly competitive, will issue its first awards next year. Although not intended to replace traditional postdoctoral training, the pilot can be scaled up if successful.

This programme is not for everyone, and postdoctoral positions will continue to expand the skills and experience of most young scientists. But for exceptional individuals with the intellectual and experimental sophistication to initiate an independent career at the end of doctoral training, this programme will provide the opportunity. I have been involved in the launch of many pilots, including that of the Human Genome Project, but I have a special affinity for this one: the future of biomedical research relies on the creativity and energy of its investigators. Unleashing that capability at all stages of a scientist's career should be a priority for us all.

Francis Collins is director of the US National Institutes of Health. e-mail: francis.collins@nih.gov

Garage bilogist

This reminds the old saying, that science can be absorbing interest to whoever with relentless curiosity and passions. Across Europe and US, a number of people are cropping up termed the so-called 'DIYbio'. They do biological experiments in their garage or kitchen or other places. They are not furnished with high-tech labs, but they run for their passions. Now they even begin to meet regularly to converse with each other. In a way, scientific activities should become common in people's daily life and not be exclusive to scientists. It is the spirit of inquiring into the Nature and liberating one's self from the ego. Unfortunately, normal education seems destroying rather than corroborating.

Nature, 467 :634 doi:10.1038/467634a

Amateur scientists who experiment at home should be welcomed by the professionals.

For the past two years, a group of molecular-biology enthusiasts has met regularly in Cambridge, Massachusetts, to discuss science. Their conservation is not entirely theoretical: they swap stories about the experiments they perform in rudimentary labs built in their kitchens, basements and garages. These meetings are not unique: similar gatherings are cropping up across the United States and Europe, as amateur scientists get together to compare protocols and results from experiments they design and conduct at home.

Do-it-yourself biologists emerged into the spotlight after the first meeting, in a Cambridge pub, in 2008. Their exploits have since earned them a moniker fit for the headlines of the twenty-first century: biohackers (see page 650). Media coverage has taken its toll on the public's perception of 'DIYbio'. Stories in the press are often peppered with sweeping claims of the monumental advances to be made by unleashing the talents of the public at large on important biological questions. Equally common are breathless warnings that a bioterrorist is busy crafting the next plague in a garage, safe from the watchful eye of the authorities.

Neither image rings true. Most biohackers are hobbyists who delight in crafting their own equipment and who tackle projects no more sophisticated than those found in an advanced high-school biology lab. This is not to belittle their achievements — the most basic lab experiments can be a challenge without the institutional infrastructure professional scientists take for granted. And it is not necessarily the sophistication of the techniques, but the questions to which they are applied, that makes for compelling science. Nevertheless, the high financial and educational barriers to cutting-edge molecular biology means that garage labs are unlikely to solve the world's energy or health problems any time soon. As for that imagined bioterrorist, US experts at the FBI's Weapons of Mass Destruction Directorate have investigated and found no sign of a biohacker who intends harm.

Nevertheless, the bureau is wise to plan ahead. The FBI has embarked on a laudable and proactive programme to establish ties with the amateur biology community. FBI agents attend DIYbio meetings and invite DIYbio leaders to conferences on bioterrorism. This has yielded some practical plans, such as notifying police and fire stations about local garage labs, to avoid unpleasant surprises or false alarms in the event of an emergency. But some in the biohacking community worry that the constant focus on bioterrorism has taken attention and resources away from a more pressing issue: basic biosafety. How should a biohacker dispose of unwanted genetically engineered bacteria? How does an amateur biologist avoid exposure to fumes from the chemicals used to isolate and manipulate DNA? What is a safe bacterium for a hobbyist to play with?

These are questions that crop up daily in a garage lab, and amateur biologists have struggled to find answers. Although institutions such as the US National Institutes of Health (NIH) and the Centers for Disease Control and Prevention have established biosafety guidelines, these are aimed at institutional biosafety officers with training in the field. Laden with jargon and focused on advanced work with dangerous chemicals and pathogens that hobbyists are unlikely to encounter, the guidelines are little help in the garage. Does this knowledge gap provide an opportunity for professional scientists to engage and support the DIYbio community? Some researchers argue it does, with professionals helping garage biologists craft safety guidelines and standards that could be understood by the enthusiast. Biohackers could also be brought onto biosafety committees at their local university or medical centre. These committees are required by the NIH to include at least one member who is not a professional scientist. Serving on a such committee would expose the hobbyist to the regulations and protocols that research institutions use to protect workers and the environment.

Biohackers are an example of the growing 'citizen science' movement, in which the public takes an active role in scientific experiments. Citizen science can help stimulate public support for science, and can introduce fresh ideas from novel disciplines. Science is a professional business but it would be a shame if the only interested knock on the hobbyists' doors came from those in law enforcement.

A Brief story of Feynman

On BBC radio Feynman was paid a tribute by Brian Cox, who is a particle physicist in Manchester University in UK.

Producing FFLO states

Nature, 467: 535–536:

Atomic gases cooled down to nanokelvin temperatures and confined in optical or magnetic traps have helped to realize and investigate fundamental many-body quantum phases of matter^{1, 2}. An investigation by Liao et al.³ on page 567 of this issue now shows how such ultracold systems are also moving to centre stage in the quest for an exotic form of superconductivity — the elusive FFLO superconducting state of matter that was proposed more than 40 years ago by Fulde and Ferrell⁴ and Larkin and Ovchinnikov⁵.

In condensed-matter physics, an arbitrarily small attraction between fermions (particles with half-integer spin, such as electrons) of identical but opposing spin and momentum can lead to the formation of bound pairs that have bosonic character (bosons being particles with whole-integer spin). Under specific conditions, such pairs can undergo the phenomenon of Bose–Einstein condensation (BEC), transforming the many-body system into a 'giant matter wave' with spectacular frictionless-flow properties — a superconductor or superfluid is born. This remarkable outcome of pairing, first proposed by Bardeen, Cooper and Schrieffer (BCS), is considered to be the conventional way in which superconductivity emerges in a wide range of materials. In the world of atomic physics, the same pairing mechanism has been studied thoroughly in three dimensions with equal two-component gas mixtures of fermionic neutral atoms^{1, 2}, each component comprising atoms with one of two spin states (up or down). But what happens to such a BCS superfluid state if the two fermionic spin states are not present in equal numbers in the system?

In a solid-state material, such a spin-imbalance condition can be created by applying a magnetic field to the system. In ultracold atomic gases, a simple initial difference in the number of spin-up and spin-down atoms will do the job. Intuitively, one might think that an increasing mismatch in the number of spin-up and spin-down particles would make it harder for the opposing spins to meet each other and pair up, thus hindering superconductivity. And this is indeed what happens in experiments. Put in more technical terms, the Fermi surfaces of the two system components will have different sizes, and this difference will hamper the formation of the pairs and the ensuing BCS superfluid state (the Fermi surface is the boundary in momentum space that separates unoccupied states from occupied ones).

Fulde and Ferrell⁴, as well as Larkin and Ovchinnikov⁵, proposed a clever solution that would still allow a superfluid state to exist under spin-imbalanced conditions. They suggested a paired state in which the pairs are not at rest but instead have a net momentum. This FFLO state can be viewed as a kind of microscale phase separation, containing alternating superfluid regions and normal, non-superfluid regions, in which the extra atoms of the spin species that are in excess squeeze in. Although searches for such an exotically paired FFLO state have been carried out exhaustively in condensed-matter systems, and more recently in ultracold atomic gases, unambiguous experimental evidence has remained elusive. In their study, Liao et al.³ take a major step towards creating an FFLO state using ultracold fermionic atoms.

Seeing the image obscured by painted glasses

This is an interesting innovation. Unfortunately, I cant access the original article !

A new laser technique can capture an image of an object obscured behind painted glass.

Sylvain Gigan and his team at ESPCI ParisTech in France have devised a method that traces the scattered path that photons take as they pass through an opaque white material. On one side of a glass slide covered in thick white paint, the researchers projected the image of a flower. They illuminated this set-up with a laser and took a photograph from the slide's other side. After calculating the light's zigzagging journey through the painted glass, they were able to reconstruct the flower image.

With improvements, the technique might one day be used in medical imaging to see through opaque biological tissue such as skin.

Nature Commun. doi:10.1038/ncomms1078 (2010)

This year's Nobel Prize

This year's Nobel Prize has been conferred on two Russian-born British scientists, who made breakthrough in making single-atom thick 2D materials, namely, graphene. This graphene has been under intensive studies since their discovery. Some interesting facts are as follows:
(1)2D;
(2)made of carbon atoms;
(3)consisting of both planar sigma bonds, each of which containing a localized pair of covalent electrons that found the mechanical strength, and out-of-plane pi-bonds, which are extended and occupied by mobile electrons;
(4)the pi-bands have two complete Dirac cones, due to negligible spin-orbit coupling and various symmetries: inversion symmetry, time-reversal symmetry and 6-fold rotation symmetry. In the vicinity of these cones, the physics are governed by 2D Dirac equations.
(5)because of (4), highly conductive;
(6)Quantum Hall effect and Quantum Spin Hall effect have been predicted (and the former has been observed) in this material;
Not limited by this listing, it is guaranteed that in the future more new physics shall be exploited, such as the curvature effects and optical properties.

Back from vacation

Just back from a short journey. It may take some time to catch up with the new things.