Harvesting Entities from the Web Using Unique Identifiers -- IBEX

In this paper we study the prevalence of unique entity identifiers on the Web. These are, e.g., ISBNs (for books), GTINs (for commercial products), DOIs (for documents), email addresses, and others. We show how these identifiers can be harvested systematically from Web pages, and how they can be associated with human-readable names for the entities at large scale. Starting with a simple extraction of identifiers and names from Web pages, we show how we can use the properties of unique identifiers to filter out noise and clean up the extraction result on the entire corpus. The end result is a database of millions of uniquely identified entities of different types, with an accuracy of 73--96% and a very high coverage compared to existing knowledge bases. We use this database to compute novel statistics on the presence of products, people, and other entities on the Web.Comment: 30 pages, 5 figures, 9 tables. Complete technical report for A. Talaika, J. A. Biega, A. Amarilli, and F. M. Suchanek. IBEX: Harvesting Entities from the Web Using Unique Identifiers. WebDB workshop, 201

FDI inflows in Europe: Does investment promotion work?

Can active investment promotion efforts attract FDI towards areas and sectors that would not otherwise be targeted? This paper leverages an ad hoc survey on national and sub-national Investment Promotion Agencies (IPAs) in Europe and applies state-of-the-art policy evaluation methods to estimate the impact of IPAs on FDI attraction. The results show that FDI responds to IPAs even in advanced economies. Sub-national IPAs, operating in closer proximity to investors' operations, attract FDI in particular towards less developed areas where market and institutional failures are stronger. IPAs influence FDI over and above other policies targeting the general economic improvement of the host economies. Impacts are concentrated in knowledge-intensive sectors where collaborative systemic conditions are more relevant. IPAs work best for less experienced companies - ‘occasional’ investors - more likely to suffer from institutional failures. Finally, IPAs are equally effective in attracting companies from both outside and inside the EU Single Market even if the latter are less likely to suffer from regulatory or information asymmetries. Overall, this evidence sheds new light on the role of sub-national IPAs as local ‘institutional plumbers’ in support of foreign investors and their operations

Experimental Analysis of Heat Transfer in Passive Latent Heat Thermal Energy Storage Systems for CSP Plants

Abstract Thermal energy storage is a key factor for efficiency, dispatchability and economic sustainability of concentrated solar plants. The latent heat storage systems could ensure a significant reduction in construction costs and environmental impact, because of its high storage energy density. In LHTES, the heat transfer between the heat transfer fluid and the storage system is strongly limited by the reduced thermal conductivity of the storage media. For operating temperatures between 200 and 600 °C, the most used storage media are salts. In order to evaluate solutions which promote the thermal conductivity, by increasing the exchange surface and/or the addition of nanoparticles to the storage media, Enea set up a small facility to test some storage concepts. In this facility, a diathermic oil flows through three elementary "shell-and-tube" storage systems, connected in series, reaching a maximum temperature of about 280 °C. The elementary storage systems are filled with a mixture of sodium and potassium nitrates salts, which melt at about 225 °C. Moreover a small percentage of alumina and silica nanoparticles were added to this mixture. The results of the experiments show an increase of the thermal diffusivity of the medium not only for the presence of fins on the heat transfer tubes but also because of convective flows within the melted fraction were established. These phenomena strongly reduce the charging times of the system (by about 30%). Instead, the presence of nanoparticles increases the thermal capacity and the thermal conductivity of the storage system but seems not to have a relevant effect on the thermal diffusivity of the mixture. This behavior depends on the type of used nanoparticles, which can significantly change over time some characteristics of the storage medium, in which they are dispersed, leaving other characteristics unchanged, according to mechanisms which are still to be well understood

Grid-Obstacle Representations with Connections to Staircase Guarding

In this paper, we study grid-obstacle representations of graphs where we assign grid-points to vertices and define obstacles such that an edge exists if and only if an $xy$-monotone grid path connects the two endpoints without hitting an obstacle or another vertex. It was previously argued that all planar graphs have a grid-obstacle representation in 2D, and all graphs have a grid-obstacle representation in 3D. In this paper, we show that such constructions are possible with significantly smaller grid-size than previously achieved. Then we study the variant where vertices are not blocking, and show that then grid-obstacle representations exist for bipartite graphs. The latter has applications in so-called staircase guarding of orthogonal polygons; using our grid-obstacle representations, we show that staircase guarding is \textsc{NP}-hard in 2D.Comment: To appear in the proceedings of the 25th International Symposium on Graph Drawing and Network Visualization (GD 2017

Regions in Covid-19 recovery

Covid-19 is undoubtedly a regional crisis, spatially uneven in its impacts. While it is too soon to talk about a transition ‘from pandemic to recovery’, with attention switching to regional development priorities and the implications of Covid-19 on regional policy, planning and development, increasingly we will need to focus on regions in their recovery phase. In this article we ask four leading researchers what this recovery phase will mean for regions. Opening the way for future discussion perspectives on regional economic recovery, resilience planning, building healthy and just places, and overcoming the ‘shadow’ pandemic indicate how this recovery phase is unfolding and what we would benefit from doing differently to ‘build back better’ and overcome ‘wicked problems’ preventing more inclusive, just and sustainable regional futures

Diffusion probabiliste dans les réseaux dynamiques

National audienceLa diffusion probabiliste est une des techniques les plus populaires pour diffuser de l'information dans les réseaux à grande échelle. Cette technique est appréciée pour sa simplicité, sa robustesse et son efficacité. Dans le cas du protocole \push, chaque nœud informé choisit à chaque étape un de ses voisins aléatoirement de manière uniforme, et lui transmet l'information. Ce protocole est connu pour permettre la diffusion en $O(\log n)$ étapes, avec forte probabilité, dans plusieurs familles de réseaux \emph{statiques} de $n$ nœuds. De plus, il a été montré empiriquement que le protocole \push\/ offre de très bonnes performances en pratique. En particulier, il se montre robuste aux évolutions dynamiques de la structure réseau. Dans cet article, nous analysons le protocole \push\/ dans le cas de réseaux \emph{dynamiques}. Nous considérons le modèle des graphes à évolution arête-markovienne, qui permet de capturer une forme de dépendance temporelle entre la structure du réseau au temps $t$ et celle au temps $t+1$. Plus précisément, une arête inexistante apparaît avec probabilité $p$, tandis qu'une arête existante disparaît avec probabilité $q$. Ayant pour objectif de coller avec des traces réelles, nous concentrons principalement notre étude sur le cas $p=\Omega(\frac{1}{n})$ et $q$ constant. Nous prouvons que, dans ce cas réaliste, le protocole \push\/ permet de diffuser l'information en $O(\log n)$ étapes, avec forte probabilité. Cette borne reste valide même lorsque, avec forte probabilité, le réseau est déconnecté à chaque étape (typiquement, lorsque $p\ll \frac{\log n}{n}$). Ce résultat démontre ainsi formellement la robustesse du protocole \push\/ dans le cadre d'évolution temporelle de la structure du réseau. La version complète de cet article, en cours de soumission, est disponible sur arXiv (voir~\cite{CCDFPS13} qui contient un sur-ensemble des résultats présentés ici)

Participatory design of a thematic questionnaire in the field of victimization studies

The paper introduces the results of a two-step process that led to the design of a new questionnaire in the field of victimization studies. A desk-based review of national Crime and Victimization Surveys from five EU countries was performed and resulted in identifying opportunities to improve the consistency among these surveys as well as the need to include more independent variables in order to measure fear of crime and its correlation with sociological variables. Then 12 experts in survey-based measures of crime-related issues were involved in a Delphi panel with the objective of enhancing a participatory design of a new questionnaire addressing individual and space-based determinants of the perception of insecurity, which has been poorly explored to date

The Parameterized Complexity of Centrality Improvement in Networks

The centrality of a vertex v in a network intuitively captures how important v is for communication in the network. The task of improving the centrality of a vertex has many applications, as a higher centrality often implies a larger impact on the network or less transportation or administration cost. In this work we study the parameterized complexity of the NP-complete problems Closeness Improvement and Betweenness Improvement in which we ask to improve a given vertex' closeness or betweenness centrality by a given amount through adding a given number of edges to the network. Herein, the closeness of a vertex v sums the multiplicative inverses of distances of other vertices to v and the betweenness sums for each pair of vertices the fraction of shortest paths going through v. Unfortunately, for the natural parameter "number of edges to add" we obtain hardness results, even in rather restricted cases. On the positive side, we also give an island of tractability for the parameter measuring the vertex deletion distance to cluster graphs