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17 August 2013 | NewScientist | 21

Foursquare check-ins tell stores where to set up shopSOCIAL media doesn’t just tell your friends what you’re up to. Location data can also be mined to provide a fast, inexpensive way to find the best spots to place new stores.

Many factors come into play when a retail firm is trying to decide where to position its new outlet: the local demographic, for example, or what transport links there are in the area. Formal analyses of this type of data can be expensive, though, and take a long time to collect.

To see whether social media can offer any insights into how consumers respond to stores’ locations, Anastasios Noulas at the University of Cambridge and colleagues analysed 35 million publicly available check-ins from 925,000 Foursquare users in New York over six months. They concentrated on information for three store chains: McDonalds, Starbucks and Dunkin’ Donuts.

The team rated how successful the stores were based on how many check-ins each one received. Then they pushed their analysis further, translating multiple check-ins by the same user into a movement pattern for that person. They used that to measure factors like overall foot traffic, and how often people travel long distances to visit an area.

Next, the team evaluated how well each factor could predict a store’s

success. They trained an algorithm on check-in data for two-thirds of the stores. Then they asked it to predict which locations out of the remaining third would be the most popular.

Each metric turned out to have a degree of predictive capability. But when the team combined all of them, the system was by far the best, accurately ranking the top 10 per cent of locations 70 per cent of the time (arxiv.org/abs/1306.1704).

Using geo-data from social networks could help retailers plan their next store openings, says

co-author Dmytro Karamshuk. “The location-based social network data allows us to trace not only the digital, but also the physical behaviour of users,” he says.

Big retail firms are beginning to appreciate how useful social media can be. A spokesperson for Sainsbury’s supermarket in the UK said: “We do not currently use social media but recognise the potential geo-data could have in supporting our development programme, and identifying the future location of stores.” Chris Baraniuk n

“Location-based social network data allows us to trace the physical behaviour of users”

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Squid camouflage for soldiers

Squid, octopus and other cephalopod masters of disguise may soon have human company. In a first step towards squid camouflage for soldiers, researchers have made a thin film out of graphene and the protein reflectin, which squid in the Loliginidae family use to hide themselves. Lowering the pH of the film causes the proteins to expand and become reflective. Raising the pH causes them to shrink and make the film invisible in infrared (Advanced Materials, doi.org/nfq).

“When you’re dying of malaria, i suppose you’ll look up and see that balloon, and i’m not sure how it’ll help you”Bill Gates comments in Businessweek on Google's Loon project, which will use balloons to provide internet connectivity in Africa

RF tags grab power from the airRadio-frequency tags have been built that harvest ambient signals from television and radio broadcasts. They can use the small amounts of power gained to communicate with each other over a short distance without any other power source. Vincent Liu at the University of Washington in Seattle and colleagues say the tags could let people swap money between accounts by tapping their credit or debit cards together, say. Liu will present the work at the SIGCOMM conference in Hong Kong, China, this week.

A cognitive leap forwardIBM is one step closer to switching on its experimental TrueNorth chips, which are designed to mimic the way our brains handle many incoming datastreams at once. To make the chips work, Dharmendra Modha and colleagues at IBM Research in San Jose, California, have designed a programming language that packages the functionality of each chip inside blocks of code they call “corelets”. These can be bundled together to make bigger corelets, each performing as part of the overall software.

130817_N_TechSpread.indd 21 12/8/13 17:59:26