Category Archives: Science

Some materials links

Invisible electronics.

To create their thin-film transistors, [Tobin J. ] Marks’ group [at Northwestern] combined films of the inorganic semiconductor indium oxide with a multilayer of self-assembling organic molecules that provides superior insulating properties.

Synthetic Gecko materials that mimics “microscopic hairs on a gecko foot”. It is “made of layers covered with thousands of stalks with splayed tips made of a polyimide, a synthetic like Nylon.”

Metamaterials with negative refractive index:

[Gunnar] Dolling’s metamaterial is made by depositing a layer of silver on a glass sheet, covering this with a thin layer of nonconducting magnesium fluoride, followed by another silver layer, forming a sandwich 100 nm thick. Dolling then etched an array of square holes through the sandwich to create a grid, similar to a wire mesh.

A key advance in Flexible electronics:

The trick to being able to manufacture—rather than handcraft—large arrays of single-crystal transistors was to devise a method for printing patterns of transistors on surfaces such as silicon wafers and flexible plastic. The first step is to put electrodes on these surfaces wherever a transistor is desired. Then the researchers make a stamp with the desired pattern out of a polymer called polydimethylsiloxane. After coating the stamp with a crystal growth agent called octadecyltriethoxysilane (OTS) and pressing it onto the surface, the researchers can then introduce a vapor of the organic crystal material onto the OTS-patterned surfaces. The vapor will condense and grow semiconducting organic single crystals only where the agent lies. With the crystals bridging the electrodes, transistors are formed.

Finally, is open peer review experiment at Nature a failure?

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Nano-knives and superplastic nanotubes

First, the nano-knife (via slashdot):

A prototype microtome knife for cutting ~100 nm thick slices of frozen-hydrated biological samples has been constructed using multiwalled carbon nanotubes (MWCNT). A piezoelectric-based 3-D manipulator was used inside a Scanning Electron Microscope (SEM) to select and position individual MWCNTs, which were subsequently welded in place using electron beam-induced deposition (EBID).

The device employs a pair of tungsten needles with provision to adjust the distance between the needle tips, accommodating various lengths of MWCNTs. We have performed experiments to test the breaking strength of the MWCNT in the completed device using an atomic force microscope (AFM) tip. An increasing force was applied at the midpoint of the nanotube till the point of failure, which was observed in-situ in the SEM.

Next, the superplastic nanotubes of carbon:

The theoretical maximum tensile strain — that is, elongation — of a single-walled carbon nanotube is almost 20%, but in practice only 6% is achieved. Here we show that, at high temperatures, individual single-walled carbon nanotubes can undergo superplastic deformation, becoming nearly 280% longer and 15 times narrower before breaking. This superplastic deformation is the result of the nucleation and motion of kinks in the structure, and could prove useful in helping to strengthen and toughen ceramics and other nanocomposites at high temperatures.

Different meanings of the word ‘replicate’

In the rough-and-tumble world of science, disputes are usually settled in time, as a convergence of evidence accumulates in favor of one hypothesis over another. Until now.

On April 10 economist John R. Lott, Jr., formerly of the American Enterprise Institute, filed a defamation lawsuit against economist Steven D. Levitt of the University of Chicago and HarperCollins, the publisher of Levitt’s 2005 book, Freakonomics. At issue is what Levitt meant when he wrote that scholars could not “replicate” Lott’s results …

That’s from Michael Shermer’s Skeptic column in Scientific American. Shermer is “executive director of the Skeptics Society, bold debunkers of all things supernatural”, according to Salon which has a long interview with him [free, if you are willing to watch an ad]. I don’t know if artificial intelligence would be considered ‘supernatural’, but here is an interesting article in the Skeptic magazine (flagship of the Skeptics Society) debunking the lofty claims made by AI enthusiasts.

The Oscars of Indian Science: 2006 Edition

Yes, the Shanti Swarup Bhatnagar (SSB) Prizes have been announced for the year 2006. As I said in my post last year, the SSB Prizes are the most prestigeous in India because (a) they represent peer recognition, and (b) they are rare (just one or two in each field). They do come with some money, but at Rs. 200,000 or about $5,000, it’s not much (but certainly nice!).

I’m pleased to note that Prof. S. Sampath, a colleague in the Department of Inorganic and Physical Chemistry, is among the SSB Prize winners [Congratulations, Sampath!]. He has won one of the two Prizes for Chemical Sciences; Dr. K George Thomas (RRL, Trivandrum) has won the other.

The two SSB Prizes for engineering go to Dr. Ashish Lele (Complex Fluids and Polymer Engineering, National Chemical Laboratory, Pune) and Dr. Sanjay Mittal (Aerospace Engineering, IIT-K).

I have to fault the Council of Scientific and Industrial Research (CSIR), the organization that awards these Prizes, for giving just the barest of details about the awardees. Is it so difficult to put together a news story that has details about each awardee’s important contributions? Wouldn’t it be nice — offering a higher profile for the Prize winners, and more information for the others — if full citations are available on the CSIR website? Currently, all that it offers is this press release [pdf] which deserves a prize for minimalism.

BMQ

A quick note to tell you — particularly those of you in Bangalore — about the Bangalore Materials Quiz (BMQ), an annual event organized by us for the students of Classes XI and XII. As the name suggests, BMQ covers all aspects of materials: their physics, chemistry, production, processing, properties (mechanical, thermal, electrical, magnetic, optical, …), applications and use.

I have created the BMQ blog which will be used to both disseminate information and coordinate our team’s activities.

BMQ is organized almost entirely by the wonderful graduate students of our Department. They orchestrate all aspects of the event, with some minimal guidance (and cheering from the sidelines) from me. This is the tenth year since I took over the responsibility of running this show, and I have met some of the brightest students (one of them runs this blog) through it.

BMQ is not a mega event; we usually get about 25 teams (of two each) every year. This year, we hope to attract 50 teams. On the other hand, we aren’t set up to handle a large number of teams either; so 50 is the hard limit!

The Prize we offer is admittedly small — books worth about Rs. 500 for each student! But the top two teams from BMQ get to take part in a grander event with bigger prizes at stake (see the blog for details).

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Well, if you know anyone in Bangalore-based schools (higher secondary schools and pre-university colleges) who might be interested in BMQ, do please spread the word. Many thanks in advance.

Manhattan Project in energy saving technologies

Wired has an article (with links) about on-going research in energy-saving technologies in MIT. Check this one out!

The research is applying new materials, new technologies and new ideas to radically improve an old concept — thermophotovoltaic (TPV) conversion of light into electricity. Rather than using the engine to turn a generator or alternator in a car, for example, the new TPV system would burn a little fuel to create super-bright light. Efficient photo diodes (which are similar to solar cells) would then harvest the energy and send the electricity off to run the various lighting, electrical and electronic systems in the car.

Such a light-based system would not replace the car’s engine. Instead it would supply enough electricity to run subsystems, consuming far less fuel than is needed to keep a heavy, multi-cylinder engine running, even at low speed. Also, the TPV system would have no moving parts; no cams, no bearings, no spinning shafts, so no energy would be spent just to keep an engine turning over, even at idle.

An explosive commentary on the status of women in science

When I was 14 years old, I had an unusually talented maths teacher. One day after school, I excitedly pointed him out to my mother. To my amazement, she looked at him with shock and said with disgust: “You never told me that he wasblack”. I looked over at my teacher and, for the first time, realized that he was an African-American. I had somehow never noticed his skin colour before, only his spectacular teaching ability. I would like to think that my parents’ sincere efforts to teach me prejudice were unsuccessful. I don’t know why this lesson takes for some and not for others. But now that I am 51, as a female-to-male transgendered person, I still wonder about it, particularly when I hear male gym teachers telling young boys “not to be like girls” in that same deroga-tory tone.

[…]

Here are a few examples of bias from my own life as a young woman. As an undergrad at the Massachusetts Institute of Technology (MIT), I was the only person in a large class of nearly all men to solve a hard maths problem, only to be told by the professor that my boyfriend must have solved it for me. I was not given any credit. I am still disappointed about the prestigious fellowship competition I later lost to a male contemporary when I was a PhD student, even though the Harvard dean who had read both applications assured me that my application was much stronger (I had published six high-impact papers whereas my male competitor had published only one). Shortly after I changed sex, a faculty member was heard to say “Ben Barres gave a great seminar today, but then his work is much better than his sister’s.”

This explosive commentary in Nature [1] by Ben Barres, a neurobiologist at Stanford, is going to be discussed quite widely. There will be a lot of spin on either side, but there’s nothing like the original. Do read Ben Barres’ very personal commentary; you will learn and understand a lot more about ‘innate differences’ (see another quote below) and ‘discrimination’ from just this one source than from the tons of spin-filled meta-commentary that’s sure to follow.

In an accompanying piece (in a side bar, I think), this is what Barres says:

As a transgendered person, no one understands more deeply than I do that there are innate differences between men and women. I suspect that my transgendered identity was caused by fetal exposure to high doses of a testosterone-like drug. But there is no evidence that sexually dimorphic brain wiring is at all relevant to the abilities needed to be successful in a chosen academic career. I underwent intensive cognitive testing before and after starting testosterone treatment about 10 years ago. This showed that my spatial abilities have increased as a consequence of taking testosterone. Alas, it has been to no avail; I still get lost all the time when driving (although I am no longer willing to ask for directions). There was one innate difference that I was surprised to learn is apparently under direct control of testosterone in adults — the ability to cry easily, which I largely lost upon starting hormone treatment. Likewise, male-to-female transgendered individuals gain the ability to cry more readily. By far, the main difference that I have noticed is that people who don’t know I am transgendered treat me with much more respect: I can even complete a whole sentence without being interrupted by a man.

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[1] The link is to Nature‘s website, and if it’s pay-walled, take a look at this story [via].

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Cross-posted at nanopolitan, my main blog.

Nikola Tesla

Couturnix has a great post — no, make that an absolutely great post — on Nikola Tesla in celebration of the latter’s 150th birthday on July 10. You’ve got to check out that post to see why I’m amazed …

Still, at least the first two commenters on that post were left rather underwhelmed by Couturnix’s link-fest. 😉 Hmmm, such is life …

Los Alamos

It has been quite a while since I noted the Los Alamos scientists’ revolt (through a blog!) that forced the then director to resign. The Economist updates us on what’s happening at Los Alamos.

… At the beginning of June the University of California, which had run Los Alamos since the days of the Manhattan Project, ceded control to a consortium known as Los Alamos National Security. Though the university remains one of the consortium’s members, it will now share what bouquets and brickbats come Los Alamos’s way with three firms that make a lot of their money as military contractors. These are Bechtel and Washington Group International, two large engineering and construction companies, and BWX technologies, a concern that specialises in managing nuclear facilities.

Unlike the university, the new consortium will be aiming to make a decent profit from its activities. It is also thought likely to change the emphasis of the laboratory from research (in a wide range of subjects, not all of them to do with defence, let alone nuclear weapons), to the more mundane business of making the detonators of nuclear warheads.

The consortium is making reassuring noises. According to Jeff Berger, its director of communications, “There is a popular misconception that we’re out to change the lab’s mission.” Nevertheless, many of Los Alamos’s researchers sense a shift of direction. Indeed, quite a few have left. …

Nature’s experiment with ‘open’ peer review

Nature, a leading science journal, is conducting an interesting experiment wherein a paper’s authors can have it reviewed ‘openly’ — like comments in a blog! This would be in addition to the regular (anonymous) review process.

While I haven’t given it much thought, others have. Arunn Narasimhan (Mechanical Engineering, IIT-Madras) has a link-ful post examining this experiment from many angles.

Nanotech research in India

[Even] with the NSTI [the Nano Science and Technology Initiative] in place, the level of funding has been sub-critical as compared to China with which India inevitably tends to be compared. In 2002, for example, compared to China’s $200 million, India spent a mere Rs.15 crores. Over the four and a half years of the NSTI, a total of about Rs.120 crores has been spent, much of which has gone towards basic research projects and related infrastructure, the implementation of which is overseen by a National Expert Committee headed by C.N.R. Rao. …

Besides funding about 100 basic science projects to date (worth about Rs.60 crores), part of the money (about Rs.20 crores) has gone towards establishing six centres for nanoscience at institutions such as the Indian Institute of Science (IISc), Bangalore, and the different IITs, six centres for nanotechnology each aimed at producing a product or a device within a reasonable time-frame and two national instrumentation/characterisation facilities. In all, 14 national institutions, including seven IITs, and 10 universities have been supported under the NSTI.

Pay no attention to the howler in that last sentence, and do read this Frontline article [Update: the link is broken; try this link] by R. Ramachandran on the state of nanoscience and nanotechnology research in India. [Thanks to Pradeepkumar for the e-mail alert.]

Sociophysics

After writing this post about economics, physics and econophysics, I was poking around the web, looking for Philip Ball’s articles. Ball is the author of the piece that I linked to in my post, and has written quite enthusiastically about “sociophysics” which seems, to me, to be mostly simulations in which independent entities (particles, people, institutions) act and react according to specific rules. From statistical physics simulations of interacting particles, we know that complex behaviour could emerge even with simple interactions among the particles, and I guess the hope in sociophysics is to show a similar correspondence between simple interactions among entities (‘agents’ seems to be the preferred term in sociophysics) and (emergence of) complex behaviour in the aggregate.

Philip Ball has a huge footprint on the web, a testimony to his prolific output, not only as a regular columnist for the Nature group of publications, but also as an author of quite a few books. Check out his website. One of his recent books, Critical Mass: How One Thing Leads to Another has specifically been about sociophysics. Some of the ideas appeared earlier in the form of a short article with a catchy title Physics of Institutions (pdf); see also this rather nice popular science piece titled Utopia Theory in PhysicsWeb.

Here are some of the reviews of this book: Bruce Edmonds, James Buchan for the Guardian, Steven Strogatz for Nature, and Tamás Vicsek for PhysicsWeb. The ‘Reviews’ section of Ball’s website has links to more of them.

Let me quote from Bruce Edmonds’ review:

… It is, in its way, the first “popular science” book covering a substantial section of social simulation, and talks about many of the main figures up to about 1990 (it does cover later work but not so comprehensively, which is understandable). Thus the work of Thomas Schelling, Ilya Prigogine, Brian Arthur, Alan Kirman, Robert Axtell, Joshua Epstein, Robert Axelrod, Paul Omerod, Martin Nowak, Per Bak, Duncan Watts, are all discussed.

In all of this the book is quite careful as to matters of fact – in detail all its statements are cautiously worded and filled with subtle caveats. However its broad message is very different, implying that abstract physics-style models have been successful at identifying some general laws and tendencies in social phenomena. It does this in two ways: firstly, by slipping between statements about the behaviour of the models and statements about the target social phenomena, so that it is able to make definite pronouncements and establish the success and relevance of its approach; and secondly, by implying that it is as well-validated as any established physics model but, in fact, only establishing that the models can be used as sophisticated analogies – ways of thinking about social phenomena. The book particularly makes play of analogies with the phase transitions observed in fluids since this was the author’s area of expertise.

This book is by no means unique in making these kinds of conflation – they are rife within the world of social simulation. The culture of physics is a complex of different attitudes, norms, procedures, tools, bodies of knowledge and social structures that are extremely effective at producing useful knowledge in some domains – it is not for nothing that physists have gained status within our society. However when this culture is transported into new domains, such as that of modelling social phenomena, the culture does not travel uniformly. Thus we have seen (and Critical Mass documents) an influx of simple, physics-style simulation models into sociology but they have arrived without the usual physists’ insistence that models predict unseen data. It is part of the culture of physics to aspire to the simplest possible model of phenomena but a model which only acted as a sort of vague analogy with respect to its phenomena would get short shrift in traditional physics domains. Yet frequently one reads social simulation work which takes the form of physics-style models and yet uses only vague, hand-waving justifications to justify its relevance (and, at best, a rough fitting of known, aggregate data). Models need to be constrained by the subject matter they are supposed to be about – there are two main ways of doing this: by ensuring the model is designed to behave as we know it should do (typically the parts of the model); and by checking the resulting behaviour against corresponding observed behaviour (often in aggregate). Sociophysics models tend to avoid either: they impose over-simple behaviour onto the design and don’t validate strongly against unseen data. Thus whilst such models may have interesting behaviour there is little reason to suppose that they do in fact represent observed social behaviour.

A point Edmonds makes is this:

[C]omplex behaviour can result from the interaction of lots of simple parts. This is now well established, but the implied corollary that the complexity we observe is a result of lots of simple interactions (or that it is useful to model this in this way) does not, of course, follow. Grounds for hope does not make it a reality.

This seems to be an intensely difficult ‘inverse’ problem, no? A related problem, which seems to be common to many ‘emergence‘ phenomena is the following: suppose you rig up a model with a certain set of rules (for interactions among the agents). And suppose that this model exhibits some complex behaviour. You are certainly within your rights to feel satisfied. However, how can we be sure that this is the only set of interaction rules that will lead to this ‘complex’ behaviour? If there are two (or more) sets of rules that give rise to (broadly) the same complex behaviour in the aggregate, which one should we choose? Even then, how can we be sure that that is the one that governs the real interactions among the agents?

Is Economics the ‘New’ Physics?

For a long time, physicists have had a reputation for boldly venturing into other disciplines. Indeed, in a recent Physics Today article recounting the history of physics since 1931, Spencer Weart specifically mentions the rise of ‘hyphenated physics’ (bio-physics, geo-physics, etc) during this period as a key development.

The natives of the other disciplines, of course, would grumble because they felt that many of these wandering physicists were promiscuous (with no long term commitment to their field) and, more importantly, arrogant. I remember a wanderer saying several years ago, “You know, these metallurgists know a lot of stuff about X. I don’t know how they know so much, but they just do!” Among the natives, the joke is that these promiscuous physicists were just looking for interesting problems, because there weren’t any in physics. I suppose all this is a part of a healthy disdain for other disciplines that scientists imbibe and develop.

I am reminded of all this by this paragraph, quoted in Peter Klein’s post (which was triggered by an earlier post):

Economists are extending the range of their studies to include all of the social sciences. . . . What is the reason why this is happening? One completely satisfying explanation . . . would be that economists have by now solved all of the major problems posed by the economic system, and, therefore, rather than become unemployed or be forced to deal with the trivial problems which remain to be solved, have decided to employ their obviously considerable talents in achieving a similar success in the other social sciences. However, it is not possible to examine any area of economics with which I have familiarity without finding major puzzles for which we have no agreed solutions, or, indeed, questions to which we have no answers at all. The reason for this movement of economists into neighbouring fields is certainly not that we have solved the problems of the economic system; it would perhaps be more plausible to argue that economists are looking for fields in which they can have some success. [from Ronald Coase’s 1978 paper titled “Economics and Contiguous Disciplines”.

Just replace ‘economics’ and ‘social sciences’ with ‘physics’ and ‘natural sciences’, respectively, and you have a perfect analogy!

[Peeter Klein’s posts also discuss and critique the ‘freakonomics’ kind of incursions into other fields; do read them.]

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Last year, the New York Times proclaimed ‘econophysics’ as one of the most noteworthy ideas of the year. Given the reputation of physics and economics in their respective domains (natural and social sciences), econophysics sounds like a marriage between two domineering individuals. Has it been a marriage filled with joy and peace? Hardly!

In a recent article in Nature (subscription required), Philip Ball (author of this survey article on interating agent models in sociology) describes the scene rather well. Here’s how the article opens:

For the past two decades, some physicists have been trying to apply their ideas and tools to an area that seems a long way from traditional physics. They are exploring the notion that there might be a kind of physics of the economy — an ‘econophysics’, as it has been dubbed1. Last year, some of these econophysicists even went as far as to suggest that economics might be “the next physical science”.

But now this unlikely marriage is showing signs of turning sour. Even those economists who at first welcomed econophysics are starting to wonder whether it is ever going to deliver on its initial promise. Early successes in modelling financial markets have not led to insights elsewhere, some complain. Matters came to a head at the Econophysics Colloquium, held at the Australian National University in Canberra last November. A group of economists attending the meeting were so dismayed with what they saw many physicists doing that they penned a forthcoming paper entitled ‘Worrying trends in econophysics’.

To me, this paragraph is telling:

So why have some of these physics-friendly economists become fed up? Although Ormerod and colleagues are highly critical of mainstream economic theory, they point out that “economics is not at all an empty box.” The Canberra critique accuses econophysicists of ignoring the existing literature — a charge also levelled at physicists when they began to dabble seriously in biology.

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Over a year ago, I covered a different kind of interdisciplinary war: the one between sociologists and physicists about the theory of social networks.

Papers retracted by chemistry professor: an update

Remember this post from three months ago? Now, we have an update by Kenneth Chang in the NYTimes. Prof. Dalibor Sames, the Columbia University professor of chemistry, who retracted two papers in March has now retracted four more papers. These papers were published in 2002 and 2003, and Sames was the lead author in all of them. Reason?

The retractions came after the experimental findings of the papers could not be reproduced by other researchers in the same laboratory.

The professor, Dalibor Sames, was the senior author of all the papers in question. Another author, Bengu Sezen, a former graduate student of Dr. Sames who received her doctorate last year, performed most of the experiments described in the papers.

Bengu Sezen, on the other hand, “has vigorously disputed the retractions. She said she had not been told that the papers were being withdrawn, and she questioned whether other members of Dr. Sames’s group had even tried to repeat the experiments.”

Janet Stemwedel, aka Dr. Free-Ride, has some more thoughts and an analysis of this episode. After examining the available evidence (all of which is from NYTimes, and through its reporter, Kenneth Chang, she has this to say:

Sames says others in his laboratory haven’t been able to reproduce Sezen’s experiments. Sezen says others in Sames’ lab already have reproduced them — and she’s willing to come back and perform the experiments herself under Sames’ supervision. No word on whether folks in other laboratories have tried to reproduce these experiments yet.

Sezen’s consternation here is understandable. The retraction of these papers seems to cast aspersions on her experimental competence, or on her integrity. But if it’s true that Sames didn’t contact her about the problems, that’s fishy.

Given the importance of reproducibility to the scientific enterprise, maybe we need to start thinking about what sort of burden of proof needs to be met before new findings are reported — and what kind of burden of proof needs to be met before we declare findings irreproducible.