Archive for the ‘Booze’ Category

I know why the phase-locked wineglass sings

Thursday, January 8th, 2009

singing-wineglasses

Here’s a neat party trick to impress your friends.

Rub your finger around the rim of a wineglass and friction causes it, and any liquid it contains, to oscillate. When this vibration produces an audible pure tone, the wine glass is said to “sing”.

Now Ana Karina Ramos Musalem and pals at the Weizmann Institute of Science in Israel have shown how to couple one singing wineglass to another so the second wineglass sings without anybody touching it.

The trick is to place both wineglasses in a sink of water (without the water overflowing into the glasses).  Rubbing one so that it sings should make the other sing too. This  phenomenon is known as phase-locking and is also responsible for populations of crickets that chirp together and fireflies that flash together.

Phase locking depends on the strength of the coupling. This is greatest when the glasses are closer together and when their resonant frequency is similar. So if you run into trouble, try moving them nearer to each other and matching their frequencies by changing the amount of water in each glass.

Then watch as jaws drop around the dinner table.

(With apologies to Maya Angelou.)

Ref: arxiv.org/abs/0901.0656: Phase locking between two singing wineglasses

The latest social network: binge drinking

Monday, June 23rd, 2008

Binge drinking

Binge drinking is “the rapid consumption of large amounts of alcohol, especially by young people, leading to serious anti-social and criminal behavior in urban centres,” say Paul Ormerod, an economist at Volterra Consulting in London, also linked to the University of Durham.

Binge drinking is a growing problem in city centers in the UK, with some 1.5 million binge drinking “events” across the country each week. Ormerod says:

“Vomiting, collapsing in the street, shouting and chanting loudly, intimidating passers-by and fighting are now regular night-time features of many British towns and cities. A particularly disturbing aspect is the huge rise in drunken and antisocial behaviour amongst young females.”

You know who you are. But why has this behavior spread so rapidly?

Ormerod and his mate Greg Wiltshire point to an interesting study of patterns of health conducted in the US, in which people were found to be much more likely to become obese if they had an outsize  friend or to stop smoking if their spouse had also stopped. Perhaps a similar kind of pattern occurs in binge drinkers, Ormerod reasoned.

To find out, he commissioned a survey of Britain’s youth, 504 18-24 year-olds, in which he asked them about their drinking patterns and those of their friends, family and colleagues.

The results are striking.  It turns out that:

  • 30 per cent of binge drinkers think that ‘all’ or ‘almost all’ of their work colleagues binge drink, compared to only 8 per cent of non-binge drinkers.
  • 54 per cent of binge drinkers think that “all” or “almost all” of their friends are binge drinkers, compared to 15 per cent of non-binge drinkers for whom “all” or “almost all” friends are binge drinkers.
  • only 3 per cent of binge drinkers have “no” or “hardly any” friends that binge drink compared to 19 per cent of non-binge drinkers.

Clearly the behaviour of people you know is linked in a significant way to your drinking habits.

Ormerod then used the data to determine that the kind of network that best describes the way these people are linked is a small world:  a network in which people are linked by a small number of steps in the manner of six degrees of separation.

And if that’s the case, binge drinking is a fashion that must be spreading like like tie-dyed T-shirts and nose studs.

That’s interesting because the fact that this is a small world network could have important implications for how to tackle the problem.

One line of thought has focused on individuals who are linked to a large number of others. These so-called hubs can have a disproportionate effect on the spread of behaviours and so targeting them would be one way to halt the spread of binge drinking.

For example, it may be that the behaviour of film stars or other widely known figures can have a disproportionate effect on the behaviour of others.

But that doesn’t seem to be the case with binge drinking. Hubs only exist in scale free networks in which the distance between people varies as a power law (so the network looks the same regardless of the resolution at which you view it).

If Ormerod’s conclusion is confirmed (he needs more data to nail it) and the pattern of binge drinking in the UK really do reflect a small world network, then this kind of targeting is unlikely to work.

Ref: arxiv.org/abs/0806.3176: ‘Binge’ Drinking in the UK: a Social Network Phenomenon

Fractal fingers and zero surface tension

Tuesday, January 22nd, 2008

Zero surface tension

Ah always thought a fingering instability was what happened after a misunderstanding on a first date.

But apparently it’s also a hydrodynamic phenomenon, when one fluid displaces another.

This kinda displacement is a complex process; so complex that in most cases it is mathematically intractable. Ya just gotta try it and see.

However, one of the few mathematically tractable examples is the 2-dimensional case of a less viscous fluid displacing a more viscous neighbor with zero surface tension.

The math predicts that fractal-like fingers of the less viscous fluid should penetrate the more viscous one.

And that’s exactly what happens. And here’s the proof, the picture above taken by Sid Nagel and colleagues at the University of Chicago. The grey area is tiny glass beads that have been sandwiched in a thin layer between two flat plates. The black area is air injected into the plates.

The glass beads behave like a liquid but because there are no forces between them, the surface tension is zero. And the air indeed displaces its more viscous neighbor forming a fractal pattern, just as the math predicts.

A neat experiment. Next up, those awkward Prom moments.

Ref: arxiv.org/abs/0712.2019: Toward the Zero Surface Tension Limit: The Granular Fingering Instability

Quantum dilemmas

Monday, August 13th, 2007

Ya wake up in the cells, your head a-boomin and a-thumpin. An officer helps loosen ya tongue, Guantamo style, and before ya even had breakfast, he’s a-shoutin and a-rantin for a confession.

There’s even a deal on the table. Rat on ya buddy in the next cell and the judge’ll cutcha some slack. Keep schtum and both of youse’ll go down together.

Ya’ll been there–the prisoner’s dilemma. And ya’ll know the best strategy is to rat on ya buddy and let him rot in jail. It ain’t nothing personal.

Now Anton “Beam-me-up, Scotty” Zeilinger at the University of Vienna has a better idea. He’s gone and created a quantum version of prisoner’s dilemma using an optical quantum computer.

In quantum prisoner’s dilemma, entanglement introduces an element of co-operation whether ya want it or not. So ratin on ya buddy gives ya no benefit over co-operatin with the cops.

This ain’t the first time anybody’s gotten all quantum with a prisoner. Jiangfeng Du and his buddies at the University of Science and Technology of China nailed a similar trick using NMR a few years ago.

But it does look like a cool way to show off the buffed-up chrome and fancy wing mirrors on Anton’s latest quantum computer. And it’ll help him and his buddies no end when Friday nite’s a-rompin and a-ruttin turns sour.

Ref: arxiv.org/abs/0708.1129: Experimental Realization of a Quantum Game on a One-way Quantum Computer

Why does the wine glass sing?

Sunday, August 12th, 2007

Ah know ya’ll like a tipple or two. Who don’t? So ya’ll know how a-strokin and a-rubbin a wet finger on a wine glass can put some sounds up.

Now Oleg “Chaser” Kirillov at Moscow State Lomonosov University says we ain’t got no ah-dear how this process of sound generation works. And to clarify things for ya’ll, he’s worked out how it occurs by considerin “a gyroscopic system with two degrees of freedom under the action of small dissipative and non-conservative positional forces, which has its origin in the models of rotating bodies of revolution being in frictional contact.

Apparently friction causes the glass to resonate at a frequency that generates sound (doh!).

Chaser Kirrolov says that if ya’ll have disc breaks that are a-squealin and a-screechin, then the same effect is to blame.

But heads up, Chaser: what we need to know is not what makes ‘em squeal, but what’ll make ‘em stop.

Ref: arxiv.org/abs/0708.0967: How to Play a Disc Brake