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Invisibility from elastic waves

A technique, which a University of Manchester press release describes quite incorrectly as a “Harry Potter style ‘cloaking’ device”, could protect buildings from earthquakes. Dr William Parnell and his team have shown that by cloaking components of structures with pressurised rubber, powerful waves such as those produced by an earthquake would not ‘see’ the building – they would simply pass around the structure and thus prevent serious damage or destruction.  The building, or important components within it, could theoretically be ‘cloaked’.

The abstract for the paper in the February 2012 issue of Proceedings of the Royal Society A, “Nonlinear pre-stress for cloaking from antiplane elastic waves“, says:

A theory is presented showing that cloaking of objects from antiplane elastic waves can be achieved by employing nonlinear elastic pre-stress in a neo-Hookean elastomeric material. This approach would appear to eliminate the requirement of metamaterials with inhomogeneous anisotropic shear moduli and density. Waves in the pre-stressed medium are bent around the cloaked (cavity) region by inducing inhomogeneous stress fields via pre-stress. The equation governing antiplane waves in the pre-stressed medium is equivalent to the antiplane equation in an unstressed medium with inhomogeneous and anisotropic shear modulus and isotropic scalar mass density. Note however that these properties are induced naturally by the pre-stress. As the magnitude of pre-stress can be altered at will, this enables objects of varying size and shape to be cloaked by placing them inside the fluid-filled deformed cavity region.

This comes as one of a series of announcements in recent years on various aspects of invisibility but the production of this sort of invisibility without the requirement for metamaterials is significant. Dr Parnell said:

Five or six years ago scientists started with light waves, and in the last few years we have started to consider other wave-types, most importantly perhaps sound and elastic waves. The real problem with the latter is that it is normally impossible to use naturally available materials as cloaks.
We showed theoretically that pre-stressing a naturally available material – rubber – leads to a cloaking effect from a specific type of elastic wave. Our team is now working hard on more general theories and to understand how this theory can be realised in practice.
This research has shown that we really do have the potential to control the direction and speed of elastic waves. This is important because we want to guide such waves in many contexts, especially in nano-applications such as in electronics for example.
If the theory can be scaled up to larger objects then it could be used to create cloaks to protect buildings and structures, or perhaps more realistically to protect very important specific parts of those structures.

Source: ‘Invisibility’ cloak could protect buildings from earthquakes.

Computer programme with 150 IQ

A computer programme has been developed which researchers believe can score “at least 150” on an IQ test. According to British Mensa, which describes itself as “the High IQ Society”, there are many standard IQ tests in use around the world but “on most intelligence tests, average IQ score is 100”. The Mensa websites lists the scores required to join Mensa on different tests:

  • Cattell III B – 148
  • Culture Fair – 132
  • Ravens Advanced Matrices – 135
  • Ravens Standard Matrices – 131
  • Wechsler Scales – 132

The result is interesting because IQ tests are based on spotting patterns that computers are often not able to spot.

IQ tests are based on two types of problems: progressive matrices, which test the ability to see patterns in pictures, and number sequences, which test the ability to see patterns in numbers. The most common math computer programmes score below 100 on IQ tests with number sequences.

The number sequence tests in question are only partly mathematical, with elements of psychology as well. One of the researchers, Claes Strannegård, said:

1, 2, …, what comes next? Most people would say 3, but it could also be a repeating sequence like 1, 2, 1 or a doubling sequence like 1, 2, 4. Neither of these alternatives is more mathematically correct than the others. What it comes down to is that most people have learned the 1-2-3 pattern.

Strannegård said of applications of the research:

Our programmes are beating the conventional math programmes because we are combining mathematics and psychology. Our method can potentially be used to identify patterns in any data with a psychological component, such as financial data. But it is not as good at finding patterns in more science-type data, such as weather data, since then the human psyche is not involved.

Source: Computer programmes that think like humans.

Nominations: Award for statistical excellence in the pharmaceutical industry

Nominations are now open for the award for statistical excellence in the pharmaceutical industry jointly made by the Royal Statistical Society and PSI (Statisticians in the Pharmaceutical Industry).

Now in its second year, the award was first made last year to Phil Woodward for “a portfolio-wide implementation of a Bayesian framework for early clinical development within a major pharmaceutical company“.

The RSS website gives the following information about criteria:

Once again, this year the award will be for the most influential example of the novel application of an existing statistical practice, or the implementation of an innovative statistical practice, in the pharmaceutical industry.

The nominees will have either employed existing or new statistical techniques or processes to enhance the planning and analysis of investigations, or developed statistical systems and processes which have strengthened the quality and efficiency of these investigations. The winning nominee(s) will have demonstrated how they identified the need for improvements, applied existing techniques or developed innovative techniques, and successfully implemented these techniques in their organization to enhance the statistical service provided.

Nominations for the award will close at 5pm on Friday, 18 May 2012. The winner(s) will be announced towards the beginning of July 2012. The RSS web site has further details and an entry form for nominations, including self-nominations. Nominations should refer to work undertaken between 1 January 2011 and 31 December 2011. In the case of projects which span more than one year, the project should have delivered the final product during this period.

Source: Nominations open for award for statistical excellence in the pharmaceutical industry.

Talk: Two Dictionaries of Mathematics, 1679 and 1989 by David Nelson

The Penguin Dictionary of Mathematics

On my book shelf is a paperback of over 460 pages of two column, densely typeset definitions of mathematical terms. The Penguin Dictionary of Mathematics (Third Edition) is edited by David Nelson. On Friday 2nd March 2012 David Nelson will give a talk to the IMA East Midlands Branch, “Two Dictionaries of Mathematics, 1679 and 1989”. The abstract for this is:

This talk attempts to describe the history, aims and content of two books. Firstly Joseph Moxon’s Mathematicks made Easie: or, a Mathematical Dictionary Explaining the Terms of Art and Difficult Phrases used in Arithmetick, Geometry, Astronomy, Astrology, and other Mathematical Sciences (1679), which was the first mathematical dictionary to be published in English. Secondly The Penguin Dictionary of Mathematics (1989), which has had subsequent editions in 1998, 2003 and 2008.

This talk will take place at the University of Nottingham at 7.30pm. As usual, no charge is made to attend meetings; non-IMA members are welcome. Full details and directions are available via the IMA East Midlands Branch website.

Deriving dynamical equations is NP-Hard

This paper has just been accepted by Physical Review Letters:

The behavior of any physical system is governed by its underlying dynamical equations. Much of physics is concerned with discovering these dynamical equations and understanding their consequences. In this work, we show that, remarkably, identifying the underlying dynamical equation from any amount of experimental data, however precise, is a provably computationally hard problem (it is NP-hard), both for classical and quantum mechanical systems. As a by-product of this work, we give complexity-theoretic answers to both the quantum and classical embedding problems, two long-standing open problems in mathematics (the classical problem, in particular, dating back over 70 years).

This paper has been accepted, so I can’t see why I shouldn’t be able to read it yet. Possibly something to do with money. The preprint is on the ArXiv, anyway.

via ScienceNOW via Slashdot, who reported it as “It’s Official: Physics is Hard”. That’s exactly the kind of unhelpful attention-grabbing headline we’re hoping to avoid here at The Aperiodical.

A commenter on Slashdot raises an interesting point:

Could we then map NP-HARD computation problems onto real world physics systems to find solutions?

Pricing bot interactions

Carlos Bueno writes about a book “Computer Game Bot Turing Test”. This, he says, is:

one of over 100,000 “books” “written” by a Markov chain running over random Wikipedia articles, bundled up and sold online for a ridiculous price. The publisher, Betascript, is notorious for this kind of thing.

He writes that the pricing bots on Amazon Marketplace have got hold of this book and are “fight epic price wars” over it.

So with “Turing Test” we have a delightful futuristic absurdity: a computer program, pretending to be human, hawking a book about computers pretending to be human, while other computer programs pretend to have used copies of it. A book that was never actually written, much less printed and read.

He then talks about his own book (Lauren Ipsum; a children’s story about computer science) and how he saw pricing bots fighting over this. The book is print-on-demand, so a bot claiming to have a used copy could simply buy a new copy and resell it for a profit. Then the bots started to undercut the retail price! Finally, the Amazon pricing bot put his book on sale at 28% discount (and Amazon swallows the difference).

My reaction to this algorithmic whipsawing has settled down to a kind of helpless bemusement… After all, I no longer have a choice. The price is now determined by the complex interaction of several independent computer programs, most of which don’t actually have a copy to sell.

Read the whole story: How Bots Seized Control of My Pricing Strategy.

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