A Dynamical Model of Twitter Activity Profiles

The advent of the era of Big Data has allowed many researchers to dig into various socio-technical systems, including social media platforms. In particular, these systems have provided them with certain verifiable means to look into certain aspects of human behavior. In this work, we are specifically interested in the behavior of individuals on social media platforms---how they handle the information they get, and how they share it. We look into Twitter to understand the dynamics behind the users' posting activities---tweets and retweets---zooming in on topics that peaked in popularity. Three mechanisms are considered: endogenous stimuli, exogenous stimuli, and a mechanism that dictates the decay of interest of the population in a topic. We propose a model involving two parameters $\eta^\star$ and $\lambda$ describing the tweeting behaviour of users, which allow us to reconstruct the findings of Lehmann et al. (2012) on the temporal profiles of popular Twitter hashtags. With this model, we are able to accurately reproduce the temporal profile of user engagements on Twitter. Furthermore, we introduce an alternative in classifying the collective activities on the socio-technical system based on the model.Comment: 10 pages, 5 figure

Simulating Congestion Dynamics of Train Rapid Transit using Smart Card Data

Investigating congestion in train rapid transit systems (RTS) in today's urban cities is a challenge compounded by limited data availability and difficulties in model validation. Here, we integrate information from travel smart card data, a mathematical model of route choice, and a full-scale agent-based model of the Singapore RTS to provide a more comprehensive understanding of the congestion dynamics than can be obtained through analytical modelling alone. Our model is empirically validated, and allows for close inspection of the dynamics including station crowdedness, average travel duration, and frequency of missed trains---all highly pertinent factors in service quality. Using current data, the crowdedness in all 121 stations appears to be distributed log-normally. In our preliminary scenarios, we investigate the effect of population growth on service quality. We find that the current population (2 million) lies below a critical point; and increasing it beyond a factor of $\sim10\%$ leads to an exponential deterioration in service quality. We also predict that incentivizing commuters to avoid the most congested hours can bring modest improvements to the service quality provided the population remains under the critical point. Finally, our model can be used to generate simulated data for analytical modelling when such data are not empirically available, as is often the case.Comment: 10 pages, 5 figures, submitted to International Conference on Computational Science 201

The Long Way Home (Travels and Wanderings in Croatian Movies in General, and in The Return, the Movie made by Antun Vrdoljak)

This article gives a short review of the travels presented in Croatian movies from the sixties, until the beginning of this century.The movie called the return (1979), made by Antun Vrdoljak, is reviewed separately; this is the movie whose title carries the implicit journey, wandering, perhaps even escape. the author’s intention was to review the movie which was not an adaptation, in order to avoid the comparison between the movie and the original text, which, in that case, would be inevitable. Also, the author used this particular film as an example which shows that because of the motion in movies there is always travel involved

Tweets on Super-typhoon Haiyan that hit the Philippines

This provides historical tweets (raw) on super-typhoon Haiyan (local name: Yolanda) and the creation dates of the tweets. This dataset was used in the following paper:<div><br><div>David CC, Ong JC, Legara EFT (2016) Tweeting Supertyphoon Haiyan: Evolving Functions of Twitter during and after a Disaster Event. PLoS ONE11(3): e0150190. https://doi.org/10.1371/journal.pone.0150190<br></div></div

Criticality of forcing directions on the fragmentation and resilience of grid networks

A general framework for probing the dynamic evolution of spatial networks comprised of nodes applying force amongst each other is presented. Aside from the already reported magnitude of forces and elongation thresholds, we show that preservation of links in a network is also crucially dependent on how nodes are connected and how edges are directed. We demonstrate that the time it takes for the networks to reach its equilibrium network structure follows a robust power law relationship consistent with Basquin's law with an exponent that can be tuned by changing only the force directions. Further, we illustrate that networks with different connection structures, node positions and edge directions have different Basquin's exponent which can be used to distinguish spatial directed networks from each other. Using an extensive waiting time simulation that spans up to over 16 orders of magnitude, we establish that the presence of memory combined with the scale-free bursty dynamics of edge breaking at the micro level leads to the evident macroscopic power law distribution of network lifetime.Published versio

Content categories by day, retweets.

<p>Content categories by day, retweets.</p