Cellphone records reveal new patterns of human activity

Switch yer mobile phone on and it checks into the local network giving your location and the time you were there. The network also records the calls you make, their frequency, duration and to whom you make them plus wherever they happen to be too.

Multiply that by the entire popualtion (mobile phone penetration approaches 100 per cent in many western countries) and you’ve got a data set that can give an unprecedented insight into the links between people and the way they move and behave.

Albert-Laszlo “Bar” Barabasi at Northeastern University in Boston and a few pals have been a-grindin’ and a-crunchin’ the data from several million cellphones and are now revealing what they’ve found.

Turns out the data can be used to identify friends and family (from the frequency and duration of calls and whether they are reciprocated), they can show how social groups evolve and how they fall apart.

The data can also suggests how to monitor the way people behave in emergencies in realtime. For example, a pile up on the freeway causes lots of rapidly moving phones grind to a halt, a few call the emergency services while others call the office/spouse/lovers. Spot that pattern and its a pretty good indication that an event has occurred. Location information might even help to determine exactly where the accident took place.

Barbara Rasi has also found previously unknown patterns in human behaviour. For example,  although the number of people making calls varies hugely during the day and night, the percentage who are on the move (ie who make consecutive calls from different lcoations) is always roughly the same. And the average distance they travel between calls in a half hour period is also stable at about 6 km. He says this is just the beginning of what will be possible with this kind of data.

What ya’ll want to know is how anonymous is it? The message is: Big Brother is watching…but he only has access to anonymized data.

But ah don’t buy it. It wasn’t so long ago that the raw data from search engines was thought to be anonymised if a person’s name was removed from it. But that myth was exploded by journalists from the New York Times who tracked down one individual using only her AOL search records.

How long before we see a similar expose with supposedly anonymized mobile phone records?

Ref: arxiv.org/abs/0710.2939: Uncovering Individual and Collective Human Dynamics from Mobile Phone Records

When the storm surge hits NYC

The Big Apple has had its toes watered by storms surges from passing hurricanes on many an occasion. But how to hold back the waters in future?

Alexander “Bonkin” Bolonkin reckons the best way to protect the city is to rap it in a textile storm surge barrier, a kinda giant gag.

Sounds good to me. When can they start?

Ref: arxiv.org/abs/0710.0195: Protection of New York City Urban Fabric With Low-Cost Textile Storm Surge Barriers

Money, it's a gas…

…so said Pink Floyd in Dark Side of the Moon. And how right they turned out to be.

The statistical rules governing the distribution of money and wealth bear more than a passing resemblance to the ideal gas laws. In fact, the statistical mechanics of money and wealth distribution have their own sub-headings in the Econophysics chapter of the forthcoming Encyclopedia of Complexity and System Science. There can be no greater accolade for an incipient field of endeavor than that.

The chapter is an excellent introduction to the physics of money, a new science that I know will be close to yer heart. It gives the history of the topic as well as the current state of the field. Believe me, this is gonna be a growth area, particularly when somebody starts mapping the way money flows through the economy onto the social structures and webs that exist within society. It’s gonna be dynamite.

Now I know what ya’ll thinkin. There ought to be some kinda secret knowledge known only to physicists that allows them to horde more than their fair share of this stuff. After all, Pink Floyd managed it.

If there is, nobody told Victor “Yak” Yakovenko, the author. Judging by Yak Yak’s dress sense, econophysics still don’t pay.

Ref: arxiv.org/abs/0709.3662: Statistical Mechanics Approach to Econophysics

Public transport: the cities most vulnerable to attack

Public transport networks are easy targets for terrorist attacks: anybody in London, Tokyo or Madrid will tell ya that. So Christian “Furbie” von Ferber at Coventry University in the UK and his buddies have decided to model a few of ’em from the point of view of network theory and find out how vulnerable they are to various kinds of attack.

Public transport networks have many small world features. For example, it’s easy to get from one point in a city to another with only a few changes in transport. Now small world networks are known to be robust under random attack but particularly vulnerable against specific organised attacks.

So Furbie von Ferber has worked out how various systems break down when stations or connections between them are removed according to predetermined rules. So this ain’t a measure of how easy it is to attack the transport system but how well the buses ‘n’ trains run after an attack (and let’s face it, in my ‘hood they don’t run too good at the best o’ times).
Here’s the list of cities he’s chosen to model: Berlin, Dallas, Dusseldorf, Hamburg, Hong Kong, Istanbul, London, Los Angeles, Moscow, Paris, Rome, Sao Paulo, Sydney and Taipei.

Strangely, no room for Madrid or Tokyo, both of which have suffered serious attacks on their transport systems.

Turns out that Paris and Hong Kong look the most robust and Dallas (do they have public transport in Dallas?) looks the most vulnerable: shout BOO and it’ll grind to a halt.

What Furbie von Ferber fails to do is say what Dallas has gotta do to strengthen its network. Of course, that wouldn’t be in any way related to the potential for consultancy fees from this work 😉

Ref: arxiv.org/abs/0709.3206: Attack Vulnerability of Public Transport Networks