netsci 2011

Posted by Daniele Quercia

i attended netsci a couple of weeks ago. here is my stream of consciousness:

lada adamic talked about how info changes as it propagates through the blogsphere, and she effectively modelled this change  as a simple urn model. more on her upcoming ICSW paper.  her future research will go into how sentiment of memes changes/evolves (this topic has been recently covered by  jure leskovec).

former navy officer duncan watts presented few macro sociological lab experiments and field experiments that he and his colleagues run on social media sites. he showed how media sites such as Twitter, Facebook, and Mechanical Turk allow researchers to measure individual level behaviour and interactions on a massive scale in real time. the good news is that  there are already guides for running experiments on those platforms  (see, for example, the tutorial at icwsm by paolacci  and mason).  the experiments he mentioned are fully reported in his latest book "Everything is Obvious". The main idea behind the book could be summarised as follows:

our intuition for human behaviour is so rich: we can "explain" essentially anything we observe. in turn, we feel like we ought to be able to predict, manage, direct the behaviours of others. yet often when we try to do these things (in government, policy, business, marketing), we fail. that is because, paradoxically, our intuition for human behaviour may actually impede our understanding of it. perhaps a more scientific behaviour would help us. the book is about experiments whose goal was to understand human behaviour at a large scale.

olivia woolley meza of  max plank presented the results of a project that measured the impact of two events (ie, island vulcan ashes and 9/11) on flight fluxes. these fluxes were modelled as  a network and metrics of interest were computed on the network - for example, they computed network fragmentation (nodes remaining in the largest connected component), and network inflation (how distances in the network decay). this study provided few intuitive take-aways, including:

  • regions geographically closer to an attack are more affected
  • between-region distancing is driven by hubs

with a presentation titled "A universal model for mobility and migration patterns", filippo simini (supervised by  marta gonzalez) turned to the question of whether it is possible to predict the number of flying/public transportation commuters between two locations. law of gravitation for masses (also called gravity model) doesn't work so well with people, and that's why they proposed a  new migration model.  the main idea of this model is that  an individual looks for a better job outside his home country and, as such, accepts the job in the closest country that has benefits higher than his home country. each country has a benefit value that  is a composite measure based on income, working hours, and general employment conditions. one  take away was that population (& not distance) is the key predictor of mobility fluxes.

giovanni petti of imperial skilfully delivered a very interesting presentation about a project called freeflow whose partners include  UK unis in london, york, kent. in this project, they have collected  data from sensors placed under speed bumps that measure the number of cars that pass and the amount of time each car has spent on a bump. traffic data has been arranged in a graph and, to identify congested areas, they run a  community detection algorithm  on the graph. it turns out that london behaves like one large giant in terms of traffic flow because of  long-range spatial correlations.

tamás vicsek studied  pigeon flocks and, more generally, studied the roles according to which birds tend to fly with each other. the main finding is that each member of a bird flock takes a specific role in a hierarchy, and roles arranged also  change over time

marta gonzalez studied the mobility of people living in different of cities (including non-US ones) and found few regularities:  for example, she found that residents of well-off areas tend to travel nearby (maybe because their areas tend to have plenty of internal resources). another interesting point is that trip length  distributions at city scale are well described by a weibull distribution. Marta also tried to reconstruct temporal activity of people living in chicago using SVD (eigen-decomposition) -  temporal activity is reconstructed only using the first 21 eigenvalues (which she called eigenactivities), and such reconstruction is also predictive of people's social demographics. the main point of this modelling exercise was to show that techniques such as principal component analysis combined with k-means are great tools to detect clusters in human activity

Filed under: Conference, Social No Comments

Social Networks and Future Internet

Posted by Daniele Quercia

I attended this cool workshop in annecy, france. Talks included (i'll cover only the 'social networks side' of the workshop):

Reliable data collection to study privacy concerns of OSN mobile users. Fehmi Abdesselem introduced a user study that is currently running amoung non-CS students in a variety of universities, including UCL and St. Andrews. The research question is  how users behave as they share information with mobile social applications. One of their papers.

Interests' semantics-driven inference of personal information. Dali Kafaar presented his research group's work on how to predict one's personal information (gender, age, …) based on what one likes in Facebook. In the future, they will work on: 1) privacy-aware technologies for recsys, smart meters, and mobile computing; 2) profiling and tracking online social networking users; and 3) user-generated content with expiration dates (a-la-ephimerizer).

How citation boosts promote scientific paradigm shifts and nobel prizes. Young-Ho Eom is studying paradigm shits in science by tracking citations of scholars (including nobel laurates) over time. (he might have a paper on PlosOne)

Sociological Basis for Social Network Analysis. Wonjae Lee recalled a quite nice spatial regression model from this paper [baller02], which is about: "One of sociology's defining debates centers on explanations of the geographic pat- terning of suicide. This classic debate is revisited using techniques of spatial analy- sis and data for two geographies: late nineteenth-century French departments, and late twentieth-century U.S. counties." [baller02] Baller, Robert D., and Kelly Richardson.  "Social Integration, Imitation and the Geographic Patterning of Suicide." 2002

Stable boundaries in social networks? Establishing and negotiating the permissible across virtual spaces and transnational boundaries. Ben Wagner discussed  how social-networking services currently decide what type of content is acceptable on social networks. It seems that social-networking services employ "community managers"  who take  final decisions on what is appropriate and what is not (extreme case: few services have outsourced the whole process to  call centres)


Filed under: Social, Workshop No Comments

Temporal Complex Network Measures for Mobile Malware Containment

Posted by John Tang

Picture the scene: you've bought a shiny new smartphone and have been customising it all weekend by installing various apps from the app store, however the following week you encounter a run of bad luck...

...first your house is burgled when you're at work, next your credit card is maxed out, your friends have been receiving spam text messages from you and to top it off, weeks later, some of your colleagues have had the same experience; what is going on?

Little beknown to you, within one of these seemingly innocuous apps lurks a piece of mobile malware (mobware) which has access to a wealth of personal information which an attacker can access remotely.  


Place-Friends: designing a link prediction system for location-based services

Posted by Salvatore Scellato

Online social networks often deploy friend recommending systems, so that new users can be discovered and new social connections can be created. Since these service have easily millions of users, recommending friends potentially involves searching a huge prediction space: this is why platforms such as Facebook, LinkedIn and Twitter merely focus their prediction efforts on friends-of-friends, that is, on users that are only 2 hops away in the social network, sharing at least a common friend. Extending prediction efforts beyond this social circle is simply not worth it.

017/365 areyoucheckedin?

Nonetheless, in location-based social networks there is an unprecedented source of potential promising candidates for recommending new friends: the places where user check-in at.  In a recent paper which will appear at the upcoming ACM SIGKDD 2011 conference we address the problem of designing a link prediction system which exploits the properties of the places that users visit.


Opportunistic Networking, Altruism and Disasters+secure p2p socnets

Posted by Jon Crowcroft

The Social Nets project just got a very good final review in Brussels (excellent and beyond expectations) - one of its outputs is a prototype p2p decentralised social net tool called Safebook.

This was partly a successor project to Haggle... ... ...

One of the premise behind Haggle and opportunistic networking was that people are altruistic more often than not - while this may not be true when too much money (relative to personal wealth) is involved, a lot fo studies show it is true particularly in disasters - I am reading this popular journalism book on the topic called "A Paradise built in hell", by Rebecca Solnit, which is heavily researched and cites many many studies to show that contrary to government fears and many hollywood disaster movies,the vast majority of people in major catastrophes "do the right thing" and do not panic and loot - from 1906 SF earthquake to the 2005 New Orleans Katrina floods , the biggest cause of unnecessary death was autoritarian policing over-reacting (to the tune of 500 deaths in SF from shootings by national guard when there was almost no looting at all and evidence that much panic was _caused_ by people being told there might be panic...)

In contrast, people carried out many activities of mutual aid - one assumes that a comms network that supported this  would work really rather well...

On another note, this UCSD study on spam finds choke point - this from Stefan Savage et al., so probably very thorough.

This is a result of a long running project with UC Berkeley which was heavily funded, so sometimes these big projects make some sense(maybe)?