Percolation of spatially constrained Erdos-R enyi networks with degree correlations

Motivated by experiments on activity in neuronal cultures [J. Soriano, M. Rodr ́ıguez Mart́ınez, T. Tlusty, and E. Moses, Proc. Natl. Acad. Sci. 105, 13758 (2008)], we investigate the percolation transition and critical exponents of spatially embedded Erd̋os-Ŕenyi networks with degree correlations. In our model networks, nodes are randomly distributed in a two-dimensional spatial domain, and the connection probability depends on Euclidian link length by a power law as well as on the degrees of linked nodes. Generally, spatial constraints lead to higher percolation thresholds in the sense that more links are needed to achieve global connectivity. However, degree correlations favor or do not favor percolation depending on the connectivity rules. We employ two construction methods to introduce degree correlations. In the first one, nodes stay homogeneously distributed and are connected via a distance- and degree-dependent probability. We observe that assortativity in the resulting network leads to a decrease of the percolation threshold. In the second construction methods, nodes are first spatially segregated depending on their degree and afterwards connected with a distance-dependent probability. In this segregated model, we find a threshold increase that accompanies the rising assortativity. Additionally, when the network is constructed in a disassortative way, we observe that this property has little effect on the percolation transition.

Social network extraction and analysis based on multimodal dyadic interaction

Social interactions are a very important component in people"s lives. Social network analysis has become a common technique used to model and quantify the properties of social interactions. In this paper, we propose an integrated framework to explore the characteristics of a social network extracted from multimodal dyadic interactions. For our study, we used a set of videos belonging to New York Times" Blogging Heads opinion blog. The Social Network is represented as an oriented graph, whose directed links are determined by the Influence Model. The links" weights are a measure of the"influence" a person has over the other. The states of the Influence Model encode automatically extracted audio/visual features from our videos using state-of-the art algorithms. Our results are reported in terms of accuracy of audio/visual data fusion for speaker segmentation and centrality measures used to characterize the extracted social network.

Nature of the Epidemic Threshold for the Susceptible-Infected-Susceptible Dynamics in Networks

We develop an analytical approach to the susceptible-infected-susceptible epidemic model that allows us to unravel the true origin of the absence of an epidemic threshold in heterogeneous networks. We find that a delicate balance between the number of high degree nodes in the network and the topological distance between them dictates the existence or absence of such a threshold. In particular, small-world random networks with a degree distribution decaying slower than an exponential have a vanishing epidemic threshold in the thermodynamic limit.

Spectral properties of the Laplacian of multiplex networks.

One of the more challenging tasks in the understanding of dynamical properties of models on top of complex networks is to capture the precise role of multiplex topologies. In a recent paper, Gómez et al. [ Phys. Rev. Lett. 110 028701 (2013)], some of the authors proposed a framework for the study of diffusion processes in such networks. Here, we extend the previous framework to deal with general configurations in several layers of networks and analyze the behavior of the spectrum of the Laplacian of the full multiplex. We derive an interesting decoupling of the problem that allow us to unravel the role played by the interconnections of the multiplex in the dynamical processes on top of them. Capitalizing on this decoupling we perform an asymptotic analysis that allow us to derive analytical expressions for the full spectrum of eigenvalues. This spectrum is used to gain insight into physical phenomena on top of multiplex, specifically, diffusion processes and synchronizability.

Question Waves: A multicast query routing algorithm for social search

This paper describes Question Waves, an algorithm that can be applied to social search protocols, such as Asknext or Sixearch. In this model, the queries are propagated through the social network, with faster propagation through more trustable acquaintances. Question Waves uses local information to make decisions and obtain an answer ranking. With Question Waves, the answers that arrive first are the most likely to be relevant, and we computed the correlation of answer relevance with the order of arrival to demonstrate this result. We obtained correlations equivalent to the heuristics that use global knowledge, such as profile similarity among users or the expertise value of an agent. Because Question Waves is compatible with the social search protocol Asknext, it is possible to stop a search when enough relevant answers have been found; additionally, stopping the search early only introduces a minimal risk of not obtaining the best possible answer. Furthermore, Question Waves does not require a re-ranking algorithm because the results arrive sorted

Innovative milieu, micro firms and local development in Barcelona

Peer-reviewed

The FaceUOC Project : An Open Social Learning experience by the Open University of Catalonia

The possibilities and expansion of the use of Web 2.0 has opened up a world of possibilities in online learning. In spite of the integration of these tools in education major changes are required in the educational design of instructional processes.This paper presents an educational experience conducted by the Open University of Catalonia using the social network Facebook for the purpose of testing a learning model that uses a participation and collaboration methodology among users based on the use of open educational resources.- The aim of the experience is to test an Open Social Learning (OSL) model, understood to be a virtual learning environment open to the Internet community, based on the use of open resources and on a methodology focused on the participation and collaboration of users in the construction of knowledge.- The topic chosen for this experience in Facebook was 2.0 Journeys: online tools and resources. The objective of this 5 weeks course was to provide students with resources for managing the various textual, photographic, audiovisual and multimedia materials resulting from a journey.- The most important changes in the design and development of a course based on OSL are the role of the teacher, the role of the student, the type of content and the methodology:- The teacher mixes with the participants, guiding them and offering the benefit of his/her experience and knowledge.- Students learn through their participation and collaboration with a mixed group of users.- The content is open and editable under different types of license that specify the level of accessibility.- The methodology of the course was based on the creation of a learning community able to self-manage its learning process. For this a facilitator was needed and also a central activity was established for people to participate and contribute in the community.- We used an ethnographic methodology and also questionnaires to students in order to acquire results regarding the quality of this type of learning experience.- Some of the data obtained raised questions to consider for future designs of educational situations based on OSL:- Difficulties in breaking the facilitator-centred structure- Change in the time required to adapt to the system and to achieve the objectives- Lack of commitment with free courses- The trend to return to traditional ways of learning- Accreditation- This experience has taught all of us that education can happen any time and in any place but not in any way.

Picnorama, la xarxa social geogràfica

Picnorama és una xarxa social, una unió entre persones i llocs geogràfics del món. En aquesta xarxa els usuaris podran veure tot tipus de fotografies de qualsevol lloc geogràfic per tal de descobrir racons del món, llocs que no sabien que existien o fins i tot planificar unes vacances. És una aplicació pensada per poder descobrir el món des de qualsevol lloc, adaptada a dispositius mòbils i personalitzada amb fotografies per temàtica.

Una nova xarxa social: RFV (Reusencs de fora vila) : Aprofitar el potencial del segle XXI

A partir de l'anàlisi d'un fet local, proposo la creació d'una nova xarxa social que permeti connectar els reusencs que viuen i treballen fora de Reus, i que estan escampats pel món. De Reus al món s'oferirà informació d'allò que passa a la ciutat i del món a Reus es retornarà talent, idees i connexions. Analitzarem les xarxes socials, el seu origen, la web 2.0, quines són les xarxes socials amb més presència arreu del planeta. Situarem en context les relacions que la ciutat de Reus manté amb els seus fills il·lustres, i amb aquells que han decidit progressar lluny de la ciutat. Avaluarem quina és la millor fórmula per crear una nova xarxa social i amb quines eines s'haurà de construir. L'objectiu de tot plegat és una nova xarxa social: RFV.

PhD Students’ Research Group Networks: a Qualitative Approach

This article examines the networks within the research groups where Spanish PhD students are pursuing their doctorate. Capó et al. (2007) used quantitative data to predict PhD students’ publishing performance from their background, attitudes, supervisors’ performance and research group networks. Variables related to the research group network had a negligible explanatory power on student performance once the remaining variables had been accounted for. In this article, a qualitative follow up of the same students is carried out using extreme case sampling and indepth interviews. The qualitative research shows networking as important for students. Out of the 115 aspects that students mention in the interviews as relevant to publishing in the qualitative research, 92 have to do with their supervisors, their research group or their network as a whole. Similarly, out of the 50 hindrances mentioned, 20 have to do with the networks or relations. The most commonly mentioned network-related topics are research group members pushing PhD students to publish, meeting researchers outside the research group, existence of other PhD students in the group, help with the PhD from group members, supervisor’s interest in the thesis, the possibility of discussing with experts on the PhD’s topic and frequent contact with the supervisor and research group members. Some of these characteristics were not, however, measured in the conventional quantitative social network survey

Diseño e implementación de la base de datos para la gestión de regalos grupales de una red social

El presente trabajo consiste en la creación de una base de datos para generar una aplicación que permita la gestión de un regalo grupal.

Virtualització de fires i ciutats

El món del videojoc està en constant evolució. Les últimes tendències marquen que els jocs online són els més acceptats per gran part dels usuaris. Aquest projecte forma part d’un videojoc orientat tant a la part més lúdica dels videojocs (visió clàssica), com a les xarxes socials i els negocis, combinat tot en una mateixa plataforma. Tot això integrat en un videojoc executable des del navegador i sense necessitat de cap tipus d’instal·lació. S’han desenvolupat una sèrie de mòduls per a satisfer les necessitats i els requeriments d’aquesta plataforma.

Mashup d'aplicacions basat en un buscador intel·ligent

Mashup de funcionalitats, basat en un cercador intel·ligent, en aquest cas pensat per a cursos, carreres màsters, etc. La finalitat és adjuntar diverses aplicacions amb l’únic propòsit que en aquest cas és un buscador però que també ens permet utilitzar eines per a la connectivitat mitjançant web Services, o xarxes socials.

Les agressions en contextos tancats de Justícia Juvenil

Aquesta recerca explora el fenomen de l'agressivitat originada en entorns tancats, com ho són els centres educatius de Justícia Juvenil de Catalunya. Aquest, però, és només un dels àmbits on la major part de les eines que s'han emprat poden ser d'utilitat. És possible estendre el camp d'aplicació a altres entorns de compliment de mesures o de tractament en règim tancat. L'ús d'eines de valoració estructurades pot ser complementat amb l'obtenció sistemàtica d'informació sobre els comportaments agressius, la qual cosa permet que els equips professionals disposin de més informació útil en termes de prevenció d'incidents. No obstant això, un aspecte rellevant en la prevenció de les agressions és la relació que un individu estableix amb la resta de persones del seu entorn. En aquest cas, s'ha incorporat l'Anàlisi de Xarxes Socials per obtenir indicadors des d'una perspectiva relacional a fi d’efectuar-ne una anàlisi conjunta amb característiques personals i de risc. Els resultats obtinguts permeten valorar aquests aspectes relacionals associats a les agressions que es van produir al Centre Educatiu durant el treball de camp. A més, la utilització d'altres eines permet caracteritzar aquestes agressions com a relativament poc greus i poc freqüents. Pel que fa als resultats de les eines de valoració de risc, s'han obtingut indicis que permeten afirmar la relació d'aquestes eines amb les agressions posteriors, motiu pel qual és factible considerar-les també com a eines vàlides per a la predicció d'incidents.

Eticket : gestió d'esdeveniments i venda d'entrades online

Avui dia, la gestió d’esdeveniments online i la seva promoció és un mercat creixent gràcies a l’evolució de la web 2.0 i a les xarxes socials. Ticketmaster és el referent, tot i així, no existeix una oferta clara per gestionar la venda d’entrades d’esdeveniments d’una mida petita o mitjana i que aprofiti les xarxes socials i la integració d’aplicacions que aquestes proporcionen. L’objectiu és realitzar una aplicació web on els usuaris (propis o de Facebook) puguin crear esdeveniments, publicar-los i promocionar-los a les xarxes socials, així com gestionar les tasques i característiques relacionades com la venda d’entrades i la llista de convidats.