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Life, services and activities within cities have commonly been studied by separate disciplines, each one independent from the others. One such approach is the computer simulation, which enables in-depth modelling and cost-effective evaluation of city phenomena. However, the adoption of integrated city simulations faces several barriers, such as managerial, social, and technical, despite its potential to support city planning and policymaking. This paper introduces the City Physiology: a new conceptual framework to facilitate the integration of city layers when designing holistic simulators. The physiology is introduced and applied through a process of three steps. Firstly, a literature review is offered in order to study the terminology and the progress already made towards integrated modelling of different urban systems. Secondly, interactions between urban systems are extracted from the approaches studied before. Finally, the pipeline to carry out the integration strategy is described. In addition to providing a conceptual tool for holistic simulations, the framework enables the discovery of new research lines generated by previously unseen connections between city layers. Being an open framework, available to all researchers to use and broaden, the authors of this paper envisage that it will be a valuable resource in establishing an exact science of cities., Comment: 34 pages (main content: 25 pages), 5 figures

The social inclusion aspects of shopping malls and their effects on our understanding of urban spaces have been a controversial argument largely discussed in the literature. Shopping malls offer an open, safe and democratic version of the public space. Many of their detractors suggest that malls target their customers in subtle ways, promoting social exclusion. In this work, we analyze whether malls offer opportunities for social mixing by analyzing the patterns of shopping mall visits in a large Latin-American city: Santiago de Chile. We use a large XDR (Data Detail Records) dataset from a telecommunication company to analyze the mobility of $387,152$ cell phones around $16$ large malls in Santiago de Chile during one month. We model the influx of people to malls in terms of a gravity model of mobility, and we are able to predict the customer profile distribution of each mall, explaining it in terms of mall location, the population distribution, and mall size. Then, we analyze the concept of social attraction, expressed as people from low and middle classes being attracted by malls that target high-income customers. We include a social attraction factor in our model and find that it is negligible in the process of choosing a mall. We observe that social mixing arises only in peripheral malls located farthest from the city center, which both low and middle class people visit. Using a co-visitation model we show that people tend to choose a restricted profile of malls according to their socio-economic status and their distance from the mall. We conclude that the potential for social mixing in malls could be capitalized by designing public policies regarding transportation and mobility., Comment: submitted to peer review

Nowadays, travel surveys provide rich information about urban mobility and commuting patterns. But, at the same time, they have drawbacks: they are static pictures of a dynamic phenomena, are expensive to make, and take prolonged periods of time to finish. However, the availability of mobile usage data (Call Detail Records) makes the study of urban mobility possible at levels not known before. This has been done in the past with good results--mobile data makes possible to find and understand aggregated mobility patterns. In this paper, we propose to analyze mobile data at individual level by estimating daily journeys, and use those journeys to build Origin-Destiny matrices to understand urban flow. We evaluate this approach with large anonymized CDRs from Santiago, Chile, and find that our method has a high correlation ($\rho = 0.89$) with the current travel survey, and that it captures external anomalies in daily travel patterns, making our method suitable for inclusion into urban computing applications., Comment: Submitted for review - please contact authors before citing. 6 pages

In micro-blogging platforms, people can connect with others and have conversations on a wide variety of topics. However, because of homophily and selective exposure, users tend to connect with like-minded people and only read agreeable information. Motivated by this scenario, in this paper we study the diversity of intermediary topics, which are latent topics estimated from user generated content. These topics can be used as features in recommender systems aimed at introducing people of diverse political viewpoints. We conducted a case study on Twitter, considering the debate about a sensitive issue in Chile, where we quantified homophilic behavior in terms of political discussion and then we evaluated the diversity of intermediary topics in terms of political stances of users., Comment: 6 pages. Presented at the International Workshop on Social Personalisation & Search, SPS2015 (co-located with SIGIR 2015)

Using Twitter during academic conferences is a way of engaging and connecting an audience inherently multicultural by the nature of scientific collaboration. English is expected to be the lingua franca bridging the communication and integration between native speakers of different mother tongues. However, little research has been done to support this assumption. In this paper we analyzed how integrated language communities are by analyzing the scholars' tweets used in 26 Computer Science conferences over a time span of five years. We found that although English is the most popular language used to tweet during conferences, a significant proportion of people also tweet in other languages. In addition, people who tweet solely in English interact mostly within the same group (English monolinguals), while people who speak other languages tend to show a more diverse interaction with other lingua groups. Finally, we also found that the people who interact with other Twitter users show a more diverse language distribution, while people who do not interact mostly post tweets in a single language. These results suggest a relation between the number of languages a user speaks, which can affect the interaction dynamics of online communities., Comment: 4 pages, 3 figures, 4 tables, submitted to ACM Hypertext and Social Media 2015

In this paper we extend our previous and only study on the dynamics of the Chilean Web. This new study doubles the time period and to the best of our knowledge is the only study of its type known about any country in the Web. The new results corroborate the trends found before, in particular the exponential growth of the Web, and reinforce the conclusion that the Web is more chaotic than we would like. Hence, modeling most Web characteristics is not trivial., Comment: Presented at the Sixth Latin American Web Congress, 2008, Vila Velha, Esp\'irito Santo, Brazil

Online social networks are known to be demographically biased. Currently there are questions about what degree of representativity of the physical population they have, and how population biases impact user-generated content. In this paper we focus on centralism, a problem affecting Chile. Assuming that local differences exist in a country, in terms of vocabulary, we built a methodology based on the vector space model to find distinctive content from different locations, and use it to create classifiers to predict whether the content of a micro-post is related to a particular location, having in mind a geographically diverse selection of micro-posts. We evaluate them in a case study where we analyze the virtual population of Chile that participated in the Twitter social network during an event of national relevance: the municipal (local governments) elections held in 2012. We observe that the participating virtual population is spatially representative of the physical population, implying that there is centralism in Twitter. Our classifiers out-perform a non geographically-diverse baseline at the regional level, and have the same accuracy at a provincial level. However, our approach makes assumptions that need to be tested in multi-thematic and more general datasets. We leave this for future work., Comment: Accepted in ChileCHI 2013, I Chilean Conference on Human-Computer Interaction