HyperANF: Approximating the Neighbourhood Function of Very Large Graphs on a Budget

The neighbourhood function N(t) of a graph G gives, for each t, the number of pairs of nodes such that y is reachable from x in less that t hops. The neighbourhood function provides a wealth of information about the graph (e.g., it easily allows one to compute its diameter), but it is very expensive to compute it exactly. Recently, the ANF algorithm (approximate neighbourhood function) has been proposed with the purpose of approximating NG(t) on large graphs. We describe a breakthrough improvement over ANF in terms of speed and scalability. Our algorithm, called HyperANF, uses the new HyperLogLog counters and combines them efficiently through broadword programming; our implementation uses overdecomposition to exploit multi-core parallelism. With HyperANF, for the first time we can compute in a few hours the neighbourhood function of graphs with billions of nodes with a small error and good confidence using a standard workstation. Then, we turn to the study of the distribution of the shortest paths between reachable nodes (that can be efficiently approximated by means of HyperANF), and discover the surprising fact that its index of dispersion provides a clear-cut characterisation of proper social networks vs. web graphs. We thus propose the spid (Shortest-Paths Index of Dispersion) of a graph as a new, informative statistics that is able to discriminate between the above two types of graphs. We believe this is the first proposal of a significant new non-local structural index for complex networks whose computation is highly scalable

Breakdown of the Onsager principle as a sign of aging

We discuss the problem of the equivalence between Continuous Time Random Walk (CTRW) and Generalized Master Equation (GME). The walker, making instantaneous jumps from one site of the lattice to another, resides in each site for extended times. The sojourn times have a distribution psi(t) that is assumed to be an inverse power law. We assume that the Onsager principle is fulfilled, and we use this assumption to establish a complete equivalence between GME and the Montroll-Weiss CTRW. We prove that this equivalence is confined to the case when psi(t) is an exponential. We argue that is so because the Montroll-Weiss CTRW, as recently proved by Barkai [E. Barkai, Phys. Rev. Lett. 90, 104101 (2003)], is non-stationary, thereby implying aging, while the Onsager principle, is valid only in the case of fully aged systems. We consider the case of a dichotomous fluctuation, and we prove that the Onsager principle is fulfilled for any form of regression to equilibrium provided that the stationary condition holds true. We set the stationary condition on both the CTRW and the GME, thereby creating a condition of total equivalence, regardless the nature of the waiting time distribution. As a consequence of this procedure we create a GME that it is a "bona fide" master equation, in spite of being non-Markovian. We note that the memory kernel of the GME affords information on the interaction between system of interest and its bath. The Poisson case yields a bath with infinitely fast fluctuations. We argue that departing from the Poisson form has the effect of creating a condition of infinite memory and that these results might be useful to shed light into the problem of how to unravel non-Markovian master equations.Comment: one file .tex, revtex4 style, 11 page

Layered Label Propagation: A MultiResolution Coordinate-Free Ordering for Compressing Social Networks

We continue the line of research on graph compression started with WebGraph, but we move our focus to the compression of social networks in a proper sense (e.g., LiveJournal): the approaches that have been used for a long time to compress web graphs rely on a specific ordering of the nodes (lexicographical URL ordering) whose extension to general social networks is not trivial. In this paper, we propose a solution that mixes clusterings and orders, and devise a new algorithm, called Layered Label Propagation, that builds on previous work on scalable clustering and can be used to reorder very large graphs (billions of nodes). Our implementation uses overdecomposition to perform aggressively on multi-core architecture, making it possible to reorder graphs of more than 600 millions nodes in a few hours. Experiments performed on a wide array of web graphs and social networks show that combining the order produced by the proposed algorithm with the WebGraph compression framework provides a major increase in compression with respect to all currently known techniques, both on web graphs and on social networks. These improvements make it possible to analyse in main memory significantly larger graphs

La svolta sociologica nelle relazioni internazionali: tre approcci e tre filoni di ricerca

This paper aims to highlight some recent development in the field of International Relations. In the last twenty years there has been a change in the study of international politics, with a growing interest for theories and concepts from sociology. The first section analyzes the contribution of historical sociology to the study of international relations and, in particular, the research area of “domestic structure and foreign policy”. The second section presents the contribution of constructivism and the research area on “security cultures”. In the third section, sociological institutionalism and the research area of “learning and foreign policy” are illustrated. The final section discusses the linkage between these approaches

Anti epidermal growth factor receptor therapy in small bowel adenocarcinoma

Rationale:Small bowel adenocarcinoma (SBA) is an uncommon gastrointestinal cancer, thus limited data about treatment for advanced disease are available. The lack of specific guidelines has justified the use of therapeutic protocols usually applied in advanced colorectal cancer. Few and preliminary data have suggested possible clinical benefit from the use of target therapy such as bevacizumab and cetuximab.Patient concerns:We present the case of a young woman who was admitted to the emergency department for acute abdominal pain, nausea, and vomiting related to a jejunal stenosis.Diagnoses:An enteroscopy with jejunal biopsy showed poorly differentiated cancerous cells suggestive for primary intestinal cancer. There were no signs of metastatic disease at radiological evaluation. A jejunal resection was subsequently carried out and the diagnosis of mucinous adenocarcinoma of the jejunum was confirmed.Interventions:The computed tomography scan performed 1 month after surgery showed metastatic disease. Therefore, the patient received combined protocols of chemotherapy and either bevacizumab or the anti-epidermal growth factor receptor (EGFR) panitumumab.Outcomes:A partial response (PR) was achieved with Folfox plus panitumumab and a maintenance therapy with panitumumab is being conducted with a mild toxicity and a progression free survival of 19 months since the beginning of panitumumab.Lessons:This is, to the best of our knowledge, the first report in the literature of a patient with SBA who has benefitted from panitumumab with an overall survival of 83 months

3D Digital Modelling and Digital History: A Methodology for Studying the Processes of Transformation of Nubian Temples and Landscape at the Lake Nasser Site

3D models are not only visualization and dissemination outcomes, but can be used to digitally collect, organize and visualize data starting from heterogeneous historical documents. In particular in this research 3D models are conceived to study the transformations of the sites along the river Nile now submerged by the Lake Nasser and the salvage of the temples. This paper illustrates the pre- liminary results and the issues about the use of 3D digital models to study the landscape and the temples before and after the construction of the Big Aswan Dam. The first results show that the discrepancy between the homogeneity of data required to build the 3D model and the non-homogeneity of historical documents is at the same time the weakness and the strength of the method, since it forces to explore new hypothesis and a proper use of paradata to manage the reliability of historical data

To the borders of Art Nouveau

Czernowitz, former capital of the Bukowina in the Hapsburg Empire, changed its political context twice and loose its role and visibility. Harbin, built as a Russian "island" in Northern China beyond the borderline was a major railway town along the Transiberian line branch, established in 1905, but today is a Chinese megalopolis. In both cities – flourished between XIXth and XXth centuries - the Jewish community played a major role. The paper compares these cities where Art Nouveau architecture was the key way to exhibit their “modernity”. In both towns the landmarks, the urban icons “speak” the same architectural Art Nouveau language: the theatre, the Postsparkasse and the new railway station in Czernowitz, the CER (China Eastern Railway) buildings in Harbin, here according to the Russian (Europe-based) spread of the style. These two case-studies, not so well known, worth a focus to show how the European spread of Art Nouveau went to the limit, in areas that were intended as the extreme outposts of the Western-style Civilization as a link to join people and cultures

Breaking Consensus, Transforming Metabolisms : Notes on direct-action against fossil fuels through Urban Political Ecology

This article discusses the politics of “direct- action” against fossil fuels put forward by climate justice movements, focusing in particular on the tactic of the blockade. Drawing on the conceptual toolkit of Urban Political Ecology, the argument moves from a critique of the consensual regime of climate change governance to highlight conflict and dissent as central forces for the transformation of the socio-ecological metabolisms structuring the capitalist urbanization of nature—of which fossil fuels constitute the lifeblood. This approach shifts the debate around climate change politics from an issue of technological transition to one of metabolic transformation. On this basis, the article proposes a characterization of direct-action against fossil fuels as expressions of metabolic activism: instances of grassroots eco-political engagement that aim to break consensus by disrupting capitalist-driven metabolic relations while also experimenting with alternative values, knowledges, spaces, and socio-material relations. To ground these reflections, the article offers an account of the Swedish climate justice coalition Fossilgasfällan and of its successful three-year campaign, culminated in a blockade, to halt the expansion of the gas terminal of Gothenburg port

A Dialog on the First 20 Years of PML Research and the Next 20 Ahead

This introductory article has been written in the form of a conversation between Pier Paolo Pandolfi, Director of the Cancer Center of Beth Israel Deaconess Medical Center in Boston, and Rosa Bernardi, a former post-doctoral fellow in the laboratory of Dr. Pandolfi, now principal investigator at San Raffaele Scientific Institute in Milan, Italy. We have chosen this atypical review format because we want to offer to our readers a more direct and personal perspective on the first 20 years of research over the promyelocytic leukemia gene. This article begins as an interview, but soon transforms into a dialog where we exchange our thoughts on a number of issues around the past, present, and future research over the biology of PML. We were particularly keen on emphasizing the aspects that we find most interesting or challenging, therefore, we warn our readers that this will not be a comprehensive essay but rather a very personal view of what has been, is, and will be exciting and interesting in the PML world, in our opinion