Identification of network modules by optimization of ratio association

We introduce a novel method for identifying the modular structures of a network based on the maximization of an objective function: the ratio association. This cost function arises when the communities detection problem is described in the probabilistic autoencoder frame. An analogy with kernel k-means methods allows to develop an efficient optimization algorithm, based on the deterministic annealing scheme. The performance of the proposed method is shown on a real data set and on simulated networks

Gabriel Triangulations and Angle-Monotone Graphs: Local Routing and Recognition

A geometric graph is angle-monotone if every pair of vertices has a path between them that---after some rotation---is $x$- and $y$-monotone. Angle-monotone graphs are $\sqrt 2$-spanners and they are increasing-chord graphs. Dehkordi, Frati, and Gudmundsson introduced angle-monotone graphs in 2014 and proved that Gabriel triangulations are angle-monotone graphs. We give a polynomial time algorithm to recognize angle-monotone geometric graphs. We prove that every point set has a plane geometric graph that is generalized angle-monotone---specifically, we prove that the half-$\theta_6$-graph is generalized angle-monotone. We give a local routing algorithm for Gabriel triangulations that finds a path from any vertex $s$ to any vertex $t$ whose length is within $1 + \sqrt 2$ times the Euclidean distance from $s$ to $t$. Finally, we prove some lower bounds and limits on local routing algorithms on Gabriel triangulations.Comment: Appears in the Proceedings of the 24th International Symposium on Graph Drawing and Network Visualization (GD 2016

Provenance, manufacturing and corrosion behavior of Ancient Hellenistic coins from Egypt

Some copper alloy coins of the Ptolemaic period from a private collection, providing valuable evidence for both archaeometric as well as materials science and corrosion studies, have been investigated. The coins were found in the ancient city of Bubastis, known as Tell Basta, in the Nile Delta, Egypt. The coins have been examined by optical microscopy for their metallurgical structure, analysed by X-ray fluorescence and Electron Dispersion Spectroscopy for their composition, and by X-ray diffraction for the characterisation of their corrosion products. An attempt has been made to remove part of their corrosion products by mild chemical cleaning procedures. In some areas the coins are heavily corroded by chlorides, however most of the inscriptions on the coins themselves are still decipherable. Assumptions are made on the coins provenance, the production period, the manufacturing technique and the burial environmental conditions

Further Observations of the Intermediate Mass Black Hole Candidate ESO 243-49 HLX-1

The brightest Ultra-Luminous X-ray source HLX-1 in the galaxy ESO 243-49 currently provides strong evidence for the existence of intermediate mass black holes. Here we present the latest multi-wavelength results on this intriguing source in X-ray, UV and radio bands. We have refined the X-ray position to sub-arcsecond accuracy. We also report the detection of UV emission that could indicate ongoing star formation in the region around HLX-1. The lack of detectable radio emission at the X-ray position strengthens the argument against a background AGN.Comment: 4 pages, 2 figures. Accepted 11th of Feb 2010. Contributed talk to appear in Proceedings of "X-ray Astronomy 2009: Present Status, Multi-Wavelength Approach and Future Perspectives", Bologna, Italy, September 7-11, 2009, AIP, eds. A. Comastri, M. Cappi, and L. Angelin

A language for modeling the morphogenesis process of biological system using MAS

The biological systems are Complex Adaptive Systems that can build a complex structure using interaction between cell and its environment. The process is called morphogenesis, it is study by developmental biology and applied by tissue engineering and regenerative medicine. Computational models are used by researchers to organize and communicate ideas, test hypotheses and abstractly represent behaviors, etc. Although, Agent Based Models are used in biological systems, it is necessary appropriate domain-oriented language. This work shows the progress made in the definition of a language for modeling and simulation of such systems, in order to hide details of implementation and execution of a simulation. The language concepts are demonstrated using, as study case, the morphogenesis of a heart valve in vitro.Sociedad Argentina de Informática e Investigación Operativa (SADIO

A language for modeling the morphogenesis process of biological system using MAS

The biological systems are Complex Adaptive Systems that can build a complex structure using interaction between cell and its environment. The process is called morphogenesis, it is study by developmental biology and applied by tissue engineering and regenerative medicine. Computational models are used by researchers to organize and communicate ideas, test hypotheses and abstractly represent behaviors, etc. Although, Agent Based Models are used in biological systems, it is necessary appropriate domain-oriented language. This work shows the progress made in the definition of a language for modeling and simulation of such systems, in order to hide details of implementation and execution of a simulation. The language concepts are demonstrated using, as study case, the morphogenesis of a heart valve in vitro.Sociedad Argentina de Informática e Investigación Operativa (SADIO

Finite volume approximation of a diffusion-dissolution model and application to nuclear waste storage

International audienceThe study of two phase flow in porous media under high capillary pressures, in the case where one phase is incompressible and the other phase is gaseous, shows complex phenomena. We present in this paper a numerical approximation method, based on a two pressures formulation in the case where both phases are miscible, which is shown to also handle the limit case of immiscible phases. The space discretization is performed using a finite volume method, which can handle general grids. The efficiency of the formulation is shown on three numerical examples related tounderground waste disposal situations

Moral hazard and selection for voluntary deductibles

This paper investigates whether the voluntary deductible in the Dutch health insurance system reduces moral hazard or acts only as a cost reduction tool for low-risk individuals. We use a sample of 14,089 observations, comprising 2,939 individuals over seven waves from the Longitudinal Internet Studies for the Social sciences panel for the analysis. We employ bivariate models that jointly model the choice of a deductible and health care utilization and supplement the identification with an instrumental variable strategy. The results show that the voluntary deductible reduces moral hazard, especially in the decision to visit a doctor (extensive margin) compared with the number of visits (intensive margin). In addition, a robustness test shows that selection on moral hazard is not present in this context.</p

Complexity of Products: The Effect of Data Regularisation

Among several developments, the field of Economic Complexity (EC) has notably seen the introduction of two new techniques. One is the Bootstrapped Selective Predictability Scheme (SPSb), which can provide quantitative forecasts of the Gross Domestic Product of countries. The other, Hidden Markov Model (HMM) regularisation, denoises the datasets typically employed in the literature. We contribute to EC along three different directions. First, we prove the convergence of the SPSb algorithm to a well-known statistical learning technique known as Nadaraya-Watson Kernel regression. The latter has significantly lower time complexity, produces deterministic results, and it is interchangeable with SPSb for the purpose of making predictions. Second, we study the effects of HMM regularization on the Product Complexity and logPRODY metrics, for which a model of time evolution has been recently proposed. We find confirmation for the original interpretation of the logPRODY model as describing the change in the global market structure of products with new insights allowing a new interpretation of the Complexity measure, for which we propose a modification. Third, we explore new effects of regularisation on the data. We find that it reduces noise, and observe for the first time that it increases nestedness in the export network adjacency matrix

Embedding Four-directional Paths on Convex Point Sets

A directed path whose edges are assigned labels "up", "down", "right", or "left" is called \emph{four-directional}, and \emph{three-directional} if at most three out of the four labels are used. A \emph{direction-consistent embedding} of an \mbox{$n$-vertex} four-directional path $P$ on a set $S$ of $n$ points in the plane is a straight-line drawing of $P$ where each vertex of $P$ is mapped to a distinct point of $S$ and every edge points to the direction specified by its label. We study planar direction-consistent embeddings of three- and four-directional paths and provide a complete picture of the problem for convex point sets.Comment: 11 pages, full conference version including all proof